| blob | 475f2181cc4909efcc107f4e14c55eaa445d8885 |
1 /* Handle parameterized types (templates) for GNU -*- C++ -*-.
2 Copyright (C) 1992-2024 Free Software Foundation, Inc.
3 Written by Ken Raeburn (raeburn@cygnus.com) while at Watchmaker Computing.
4 Rewritten by Jason Merrill (jason@cygnus.com).
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
11 any later version.
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /* Known bugs or deficiencies include:
24 all methods must be provided in header files; can't use a source
25 file that contains only the method templates and "just win".
27 Fixed by: C++20 modules. */
52 /* The type of functions taking a tree, and some additional data, and
53 returning an int. */
56 /* The PENDING_TEMPLATES is a list of templates whose instantiations
57 have been deferred, either because their definitions were not yet
58 available, or because we were putting off doing the work. */
60 {
63 };
77 /* Live only within one (recursive) call to tsubst_expr. We use
78 this to pass the statement expression node from the STMT_EXPR
79 to the EXPR_STMT that is its result. */
82 // -------------------------------------------------------------------------- //
83 // Local Specialization Stack
84 //
85 // Implementation of the RAII helper for creating new local
86 // specializations.
89 {
91 ;
94 else
96 }
99 {
101 {
104 }
105 }
107 /* True if we've recursed into fn_type_unification too many times. */
111 {
115 };
117 /* The general template is not in these tables. */
122 /* Contains canonical template parameter types. The vector is indexed by
123 the TEMPLATE_TYPE_IDX of the template parameter. Each element is a
124 TREE_LIST, whose TREE_VALUEs contain the canonical template
125 parameters of various types and levels. */
128 #define UNIFY_ALLOW_NONE 0
129 #define UNIFY_ALLOW_MORE_CV_QUAL 1
130 #define UNIFY_ALLOW_LESS_CV_QUAL 2
131 #define UNIFY_ALLOW_DERIVED 4
132 #define UNIFY_ALLOW_INTEGER 8
133 #define UNIFY_ALLOW_OUTER_LEVEL 16
134 #define UNIFY_ALLOW_OUTER_MORE_CV_QUAL 32
135 #define UNIFY_ALLOW_OUTER_LESS_CV_QUAL 64
138 tbr_incomplete_type,
139 tbr_ambiguous_baseclass,
140 tbr_success
141 };
230 /* Make the current scope suitable for access checking when we are
231 processing T. T can be FUNCTION_DECL for instantiated function
232 template, VAR_DECL for static member variable, or TYPE_DECL for
233 for a class or alias template (needed by instantiate_decl). */
235 void
237 {
249 /* An artificial deduction guide should have the same access as
250 the constructor. */
252 else
256 {
259 }
260 }
262 /* Restore the scope set up by push_access_scope. T is the node we
263 are processing. */
265 void
267 {
277 else
279 }
281 /* Do any processing required when DECL (a member template
282 declaration) is finished. Returns the TEMPLATE_DECL corresponding
283 to DECL, unless it is a specialization, in which case the DECL
284 itself is returned. */
286 tree
288 {
295 {
296 tree type;
304 {
308 }
310 }
315 {
317 {
320 }
321 else
323 }
324 else
329 }
331 /* Create a template info node. */
333 tree
335 {
340 }
342 /* DECL_TEMPLATE_INFO, if applicable, or NULL_TREE. */
344 static tree
346 {
347 /* This needs to match template_info_decl_check. */
350 {
364 }
366 }
368 /* Return the template info node corresponding to T, whatever T is. */
370 tree
372 {
394 }
396 /* Returns the template nesting level of the indicated class TYPE.
398 For example, in:
399 template <class T>
400 struct A
401 {
402 template <class U>
403 struct B {};
404 };
406 A<T>::B<U> has depth two, while A<T> has depth one.
407 Both A<T>::B<int> and A<int>::B<U> have depth one, if
408 they are instantiations, not specializations.
410 This function is guaranteed to return 0 if passed NULL_TREE so
411 that, for example, `template_class_depth (current_class_type)' is
412 always safe. */
414 int
416 {
420 {
430 {
433 else
435 }
438 else
440 }
443 }
445 /* Return TRUE if NODE instantiates a template that has arguments of
446 its own, be it directly a primary template or indirectly through a
447 partial specializations. */
448 static bool
450 {
462 /* So now we know we have a specialization, but it could be a full
463 or a partial specialization. To tell which, compare the depth of
464 its template arguments with those of its context. */
473 }
475 /* Subroutine of maybe_begin_member_template_processing.
476 Returns true if processing DECL needs us to push template parms. */
478 static bool
480 {
486 }
488 /* Subroutine of maybe_begin_member_template_processing.
489 Push the template parms in PARMS, starting from LEVELS steps into the
490 chain, and ending at the beginning, since template parms are listed
491 innermost first. */
493 static void
495 {
503 current_template_parms
511 NULL);
513 {
522 {
529 /* Push the CONST_DECL. */
535 }
536 }
537 }
539 /* Restore the template parameter context for a member template, a
540 friend template defined in a class definition, or a non-template
541 member of template class. */
543 void
545 {
546 tree parms;
551 {
554 /* Disregard full specializations (c++/60999). */
557 }
560 {
565 {
568 }
571 }
573 /* Remember how many levels of template parameters we pushed so that
574 we can pop them later. */
576 }
578 /* Undo the effects of maybe_begin_member_template_processing. */
580 void
582 {
591 {
595 }
596 }
598 /* Return a new template argument vector which contains all of ARGS,
599 but has as its innermost set of arguments the EXTRA_ARGS. */
601 tree
603 {
604 tree new_args;
622 }
624 /* Like add_to_template_args, but only the outermost ARGS are added to
625 the EXTRA_ARGS. In particular, all but TMPL_ARGS_DEPTH
626 (EXTRA_ARGS) levels are added. This function is used to combine
627 the template arguments from a partial instantiation with the
628 template arguments used to attain the full instantiation from the
629 partial instantiation.
631 If ARGS is a TEMPLATE_DECL, use its parameters as args. */
633 tree
635 {
636 tree new_args;
641 {
644 }
646 /* If there are more levels of EXTRA_ARGS than there are ARGS,
647 something very fishy is going on. */
650 /* If *all* the new arguments will be the EXTRA_ARGS, just return
651 them. */
655 /* For the moment, we make ARGS look like it contains fewer levels. */
660 /* Now, we restore ARGS to its full dimensions. */
664 }
666 /* Return the N levels of innermost template arguments from the ARGS. */
668 tree
670 {
671 tree new_args;
677 /* If N is 1, just return the innermost set of template arguments. */
681 /* If we're not removing anything, just return the arguments we were
682 given. */
688 /* Make a new set of arguments, not containing the outer arguments. */
695 }
697 /* The inverse of get_innermost_template_args: Return all but the innermost
698 EXTRA_LEVELS levels of template arguments from the ARGS. */
700 static tree
702 {
703 tree new_args;
709 /* If N is 1, just return the outermost set of template arguments. */
713 /* If we're not removing anything, just return the arguments we were
714 given. */
719 /* Make a new set of arguments, not containing the inner arguments. */
726 }
728 /* We've got a template header coming up; push to a new level for storing
729 the parms. */
731 void
733 {
734 /* We use a non-tag-transparent scope here, which causes pushtag to
735 put tags in this scope, rather than in the enclosing class or
736 namespace scope. This is the right thing, since we want
737 TEMPLATE_DECLS, and not TYPE_DECLS for template classes. For a
738 global template class, push_template_decl handles putting the
739 TEMPLATE_DECL into top-level scope. For a nested template class,
740 e.g.:
742 template <class T> struct S1 {
743 template <class T> struct S2 {};
744 };
746 pushtag contains special code to insert the TEMPLATE_DECL for S2
747 at the right scope. */
753 /* Add a dummy parameter level while we process the parameter list. */
754 current_template_parms
757 current_template_parms);
758 }
760 /* This routine is called when a specialization is declared. If it is
761 invalid to declare a specialization here, an error is reported and
762 false is returned, otherwise this routine will return true. */
764 static bool
766 {
769 /* [temp.expl.spec]
771 An explicit specialization shall be declared in the namespace of
772 which the template is a member, or, for member templates, in the
773 namespace of which the enclosing class or enclosing class
774 template is a member. An explicit specialization of a member
775 function, member class or static data member of a class template
776 shall be declared in the namespace of which the class template
777 is a member. */
779 {
782 }
784 /* [temp.expl.spec]
786 In an explicit specialization declaration for a member of a class
787 template or a member template that appears in namespace scope,
788 the member template and some of its enclosing class templates may
789 remain unspecialized, except that the declaration shall not
790 explicitly specialize a class member template if its enclosing
791 class templates are not explicitly specialized as well. */
793 {
796 }
799 }
801 /* We've just seen template <>. */
803 bool
805 {
809 }
811 /* Called at then end of processing a declaration preceded by
812 template<>. */
814 void
816 {
819 }
821 /* Any template <>'s that we have seen thus far are not referring to a
822 function specialization. */
824 void
826 {
829 }
831 /* We've just seen a template header. If SPECIALIZATION is nonzero,
832 it was of the form template <>. */
834 static void
836 {
838 template_header_count++;
839 }
841 /* We're beginning an explicit instantiation. */
843 void
845 {
848 }
851 void
853 {
856 }
858 /* An explicit specialization or partial specialization of TMPL is being
859 declared. Check that the namespace in which the specialization is
860 occurring is permissible. Returns false iff it is invalid to
861 specialize TMPL in the current namespace. */
863 static bool
865 {
868 /* [tmpl.expl.spec]
870 An explicit specialization shall be declared in a namespace enclosing the
871 specialized template. An explicit specialization whose declarator-id is
872 not qualified shall be declared in the nearest enclosing namespace of the
873 template, or, if the namespace is inline (7.3.1), any namespace from its
874 enclosing namespace set. */
877 {
880 }
883 /* Same or enclosing namespace. */
885 else
886 {
887 auto_diagnostic_group d;
893 }
894 }
896 /* SPEC is an explicit instantiation. Check that it is valid to
897 perform this explicit instantiation in the current namespace. */
899 static void
901 {
902 tree ns;
904 /* DR 275: An explicit instantiation shall appear in an enclosing
905 namespace of its template. */
911 }
913 /* Returns true if TYPE is a new partial specialization that needs to be
914 set up. This may also modify TYPE to point to the correct (new or
915 existing) constrained partial specialization. */
917 static bool
919 {
920 /* An implicit instantiation of an incomplete type implies
921 the definition of a new class template.
923 template<typename T>
924 struct S;
926 template<typename T>
927 struct S<T*>;
929 Here, S<T*> is an implicit instantiation of S whose type
930 is incomplete. */
934 /* It can also be the case that TYPE is a completed specialization.
935 Continuing the previous example, suppose we also declare:
937 template<typename T>
938 requires Integral<T>
939 struct S<T*>;
941 Here, S<T*> refers to the specialization S<T*> defined
942 above. However, we need to differentiate definitions because
943 we intend to define a new partial specialization. In this case,
944 we rely on the fact that the constraints are different for
945 this declaration than that above.
947 Note that we also get here for injected class names and
948 late-parsed template definitions. We must ensure that we
949 do not create new type declarations for those cases. */
951 {
955 /* If there are no template parameters, this cannot be a new
956 partial template specialization? */
960 /* The injected-class-name is not a new partial specialization. */
964 /* If the constraints are not the same as those of the primary
965 then, we can probably create a new specialization. */
969 {
973 }
975 /* Also, if there's a pre-existing specialization with matching
976 constraints, then this also isn't new. */
979 {
985 {
988 }
990 }
992 /* Create a new type node (and corresponding type decl)
993 for the newly declared specialization. */
998 /* We only need a separate type node for storing the definition of this
999 partial specialization; uses of S<T*> are unconstrained, so all are
1000 equivalent. So keep TYPE_CANONICAL the same. */
1003 /* Build the corresponding type decl. */
1014 }
1017 }
1019 /* The TYPE is being declared. If it is a template type, that means it
1020 is a partial specialization. Do appropriate error-checking. */
1022 tree
1024 {
1025 tree context;
1030 /* A lambda that appears in specialization context is not itself a
1031 specialization. */
1035 /* An injected-class-name is not a specialization. */
1040 {
1044 }
1049 {
1055 else
1058 }
1060 {
1061 /* This is for ordinary explicit specialization and partial
1062 specialization of a template class such as:
1064 template <> class C<int>;
1066 or:
1068 template <class T> class C<T*>;
1070 Make sure that `C<int>' and `C<T*>' are implicit instantiations. */
1073 {
1080 {
1085 }
1086 }
1092 /* Trying to define a specialization either without a template<> header
1093 or in an inappropriate place. We've already given an error, so just
1094 bail now so we don't actually define the specialization. */
1096 }
1102 {
1103 /* This is for an explicit specialization of member class
1104 template according to [temp.expl.spec/18]:
1106 template <> template <class U> class C<int>::D;
1108 The context `C<int>' must be an implicit instantiation.
1109 Otherwise this is just a member class template declared
1110 earlier like:
1112 template <> class C<int> { template <class U> class D; };
1113 template <> template <class U> class C<int>::D;
1115 In the first case, `C<int>::D' is a specialization of `C<T>::D'
1116 while in the second case, `C<int>::D' is a primary template
1117 and `C<T>::D' may not exist. */
1121 {
1122 tree t;
1127 {
1130 type))
1133 }
1135 /* Check for invalid specialization after instantiation:
1137 template <> template <> class C<int>::D<int>;
1138 template <> template <class U> class C<int>::D; */
1142 {
1146 {
1147 /* We already have a full specialization of this partial
1148 instantiation, or a full specialization has been
1149 looked up but not instantiated. Reassign it to the
1150 new member specialization template. */
1151 spec_entry elt;
1164 spec_entry **slot
1169 }
1170 else
1171 /* But if we've had an implicit instantiation, that's a
1172 problem ([temp.expl.spec]/6). */
1175 }
1177 /* Mark TYPE as a specialization. And as a result, we only
1178 have one level of template argument for the innermost
1179 class template. */
1184 }
1185 }
1187 {
1188 /* Someday C++0x may allow for enum template specialization. */
1193 else
1194 {
1197 }
1198 }
1201 }
1203 /* Make sure ARGS doesn't use any inappropriate typedefs; we should have
1204 gone through coerce_template_parms by now. */
1206 static void
1208 {
1210 {
1219 /* Allow typedefs on the type of a non-type argument, since a
1221 else
1223 }
1224 }
1226 static void
1228 {
1233 }
1235 /* Retrieve the specialization (in the sense of [temp.spec] - a
1236 specialization is either an instantiation or an explicit
1237 specialization) of TMPL for the given template ARGS. If there is
1238 no such specialization, return NULL_TREE. The ARGS are a vector of
1239 arguments, or a vector of vectors of arguments, in the case of
1240 templates with more than one level of parameters.
1242 If TMPL is a type template and CLASS_SPECIALIZATIONS_P is true,
1243 then we search for a partial specialization matching ARGS. This
1244 parameter is ignored if TMPL is not a class template.
1246 We can also look up a FIELD_DECL, if it is a lambda capture pack; the
1247 result is a NONTYPE_ARGUMENT_PACK. */
1249 static tree
1251 {
1261 /* There should be as many levels of arguments as there are
1262 levels of parameters. */
1271 /* Lambda functions in templates aren't instantiated normally, but through
1272 tsubst_lambda_expr. */
1276 spec_entry elt;
1284 else
1293 }
1295 /* Like retrieve_specialization, but for local declarations. */
1297 tree
1299 {
1305 }
1307 /* Returns nonzero iff DECL is a specialization of TMPL. */
1309 int
1311 {
1312 tree t;
1315 {
1321 }
1322 else
1323 {
1332 }
1335 }
1337 /* Returns nonzero iff DECL is a specialization of friend declaration
1338 FRIEND_DECL according to [temp.friend]. */
1340 bool
1342 {
1349 /* For [temp.friend/6] when FRIEND_DECL is an ordinary member function
1350 of a template class, we want to check if DECL is a specialization
1351 if this. */
1356 {
1357 /* We want a TEMPLATE_DECL for `is_specialization_of'. */
1360 }
1365 /* There is nothing to do if this is not a template friend. */
1372 /* [temp.friend/6]
1373 A member of a class template may be declared to be a friend of a
1374 non-template class. In this case, the corresponding member of
1375 every specialization of the class template is a friend of the
1376 class granting friendship.
1378 For example, given a template friend declaration
1380 template <class T> friend void A<T>::f();
1382 the member function below is considered a friend
1384 template <> struct A<int> {
1385 void f();
1386 };
1388 For this type of template friend, TEMPLATE_DEPTH below will be
1389 nonzero. To determine if DECL is a friend of FRIEND, we first
1390 check if the enclosing class is a specialization of another. */
1397 {
1398 /* Next, we check the members themselves. In order to handle
1399 a few tricky cases, such as when FRIEND_DECL's are
1401 template <class T> friend void A<T>::g(T t);
1402 template <class T> template <T t> friend void A<T>::h();
1404 and DECL's are
1406 void A<int>::g(int);
1407 template <int> void A<int>::h();
1409 we need to figure out ARGS, the template arguments from
1410 the context of DECL. This is required for template substitution
1411 of `T' in the function parameter of `g' and template parameter
1412 of `h' in the above examples. Here ARGS corresponds to `int'. */
1419 {
1421 {
1424 else
1426 current_depth++;
1427 }
1429 }
1432 {
1434 tree friend_type;
1435 tree decl_type;
1436 tree friend_args_type;
1437 tree decl_args_type;
1439 /* Make sure that both DECL and FRIEND_DECL are templates or
1440 non-templates. */
1446 {
1447 /* If both are templates, check template parameter list. */
1448 tree friend_parms
1453 friend_parms))
1457 }
1458 else
1466 /* Check if return types match. */
1470 /* Check if function parameter types match, ignoring the
1471 `this' parameter. */
1480 }
1481 else
1482 {
1483 /* DECL is a TYPE_DECL */
1487 /* Make sure that both DECL and FRIEND_DECL are templates or
1488 non-templates. */
1489 is_template
1496 {
1497 tree friend_parms;
1498 /* If both are templates, check the name of the two
1499 TEMPLATE_DECL's first because is_friend didn't. */
1504 /* Now check template parameter list. */
1505 friend_parms
1508 return comp_template_parms
1510 friend_parms);
1511 }
1512 else
1515 }
1516 }
1518 }
1520 /* Register the specialization SPEC as a specialization of TMPL with
1521 the indicated ARGS. IS_FRIEND indicates whether the specialization
1522 is actually just a friend declaration. ATTRLIST is the list of
1523 attributes that the specialization is declared with or NULL when
1524 it isn't. Returns SPEC, or an equivalent prior declaration, if
1525 available.
1527 We also store instantiations of field packs in the hash table, even
1528 though they are not themselves templates, to make lookup easier. */
1530 static tree
1532 hashval_t hash)
1533 {
1534 tree fn;
1540 spec_entry elt;
1551 else
1554 /* We can sometimes try to re-register a specialization that we've
1555 already got. In particular, regenerate_decl_from_template calls
1556 duplicate_decls which will update the specialization list. But,
1557 we'll still get called again here anyhow. It's more convenient
1558 to simply allow this than to try to prevent it. */
1562 {
1564 {
1567 {
1569 fn);
1571 }
1572 else
1573 {
1574 tree clone;
1575 /* This situation should occur only if the first
1576 specialization is an implicit instantiation, the
1577 second is an explicit specialization, and the
1578 implicit instantiation has not yet been used. That
1579 situation can occur if we have implicitly
1580 instantiated a member function and then specialized
1581 it later.
1583 We can also wind up here if a friend declaration that
1584 looked like an instantiation turns out to be a
1585 specialization:
1587 template <class T> void foo(T);
1588 class S { friend void foo<>(int) };
1589 template <> void foo(int);
1591 We transform the existing DECL in place so that any
1592 pointers to it become pointers to the updated
1593 declaration.
1595 If there was a definition for the template, but not
1596 for the specialization, we want this to look as if
1597 there were no definition, and vice versa. */
1601 /* The call to duplicate_decls will have applied
1602 [temp.expl.spec]:
1604 An explicit specialization of a function template
1605 is inline only if it is explicitly declared to be,
1606 and independently of whether its function template
1607 is.
1609 to the primary function; now copy the inline bits to
1610 the various clones. */
1612 {
1619 }
1623 }
1624 }
1626 {
1629 /* We've already complained in duplicate_decls. */
1633 /* Dup decl failed, but this is a new definition. Set the
1634 line number so any errors match this new
1635 definition. */
1639 }
1640 }
1644 /* A specialization must be declared in the same namespace as the
1645 template it is specializing. */
1658 /* If TMPL is a forward declaration of a template function, keep a list
1659 of all specializations in case we need to reassign them to a friend
1660 template later in tsubst_friend_function.
1662 Also keep a list of all variable template instantiations so that
1663 process_partial_specialization can check whether a later partial
1664 specialization would have used it. */
1669 }
1671 /* Restricts tree and type comparisons. */
1675 /* Whether we are comparing template arguments during partial ordering
1676 (and therefore want the comparison to look through dependent alias
1677 template specializations). */
1681 /* Returns true iff two spec_entry nodes are equivalent. */
1683 bool
1685 {
1694 /* tmpl could be a FIELD_DECL for a capture pack. */
1698 {
1699 /* Partial specializations of a variable template can be distinguished by
1700 constraints. */
1704 }
1710 }
1712 /* Returns a hash for a template TMPL and template arguments ARGS. */
1714 static hashval_t
1716 {
1719 }
1721 hashval_t
1723 {
1728 }
1730 /* Returns a hash for a spec_entry node based on the TMPL and ARGS members,
1731 ignoring SPEC. */
1733 hashval_t
1735 {
1737 }
1739 /* Recursively calculate a hash value for a template argument ARG, for use
1740 in the hash tables of template specializations. We must be
1741 careful to (at least) skip the same entities template_args_equal
1742 does. */
1744 hashval_t
1746 {
1751 /* Strip nop-like things, but not the same as STRIP_NOPS. */
1762 {
1764 /* Getting here with an ARGUMENT_PACK_SELECT means we're probably
1765 preserving it in a hash table, which is bad because it will change
1766 meaning when gen_elem_of_pack_expansion_instantiation changes the
1767 ARGUMENT_PACK_SELECT_INDEX. */
1801 {
1804 {
1807 }
1809 }
1813 {
1816 }
1832 val = iterative_hash_template_arg
1844 val);
1846 val);
1855 /* [temp.over.link] Two lambda-expressions are never considered
1856 equivalent.
1858 So just hash the closure type. */
1869 /* Now hash operands as usual. */
1873 {
1876 {
1880 }
1882 call_expr_arg_iterator ai;
1887 }
1891 }
1895 {
1898 {
1899 // We want an alias specialization that survived strip_typedefs
1900 // to hash differently from its TYPE_CANONICAL, to avoid hash
1901 // collisions that compare as different in template_args_equal.
1902 // These could be dependent specializations that strip_typedefs
1903 // left alone, or untouched specializations because
1904 // coerce_template_parms returns the unconverted template
1905 // arguments if it sees incomplete argument packs.
1908 }
1911 {
1918 {
1919 /* Hash the components that are relevant to TYPENAME_TYPE
1920 equivalence as determined by structural_comptypes. We
1921 can only coherently do this when comparing_specializations
1922 is set, because otherwise structural_comptypes tries
1923 resolving TYPENAME_TYPE via the current instantiation. */
1928 }
1935 {
1938 }
1940 }
1953 }
1954 }
1956 /* Unregister the specialization SPEC as a specialization of TMPL.
1957 Replace it with NEW_SPEC, if NEW_SPEC is non-NULL. Returns true
1958 if the SPEC was listed as a specialization of TMPL.
1960 Note that SPEC has been ggc_freed, so we can't look inside it. */
1962 bool
1964 {
1966 spec_entry elt;
1974 {
1979 }
1982 }
1984 /* Like register_specialization, but for local declarations. We are
1985 registering SPEC, an instantiation of TMPL. */
1987 void
1989 {
1992 }
1994 /* Registers T as a specialization of itself. This is used to preserve
1995 the references to already-parsed parameters when instantiating
1996 postconditions. */
1998 void
2000 {
2002 }
2004 /* TYPE is a class type. Returns true if TYPE is an explicitly
2005 specialized class. */
2007 bool
2009 {
2013 }
2015 /* Print the list of functions at FNS, going through all the overloads
2016 for each element of the list. Alternatively, FNS cannot be a
2017 TREE_LIST, in which case it will be printed together with all the
2018 overloads.
2020 MORE and *STR should respectively be FALSE and NULL when the function
2021 is called from the outside. They are used internally on recursive
2022 calls. print_candidates manages the two parameters and leaves NULL
2023 in *STR when it ends. */
2025 static void
2027 {
2031 else
2033 {
2039 {
2042 else
2045 }
2047 }
2048 }
2050 /* Print the list of candidate FNS in an error message. FNS can also
2051 be a TREE_LIST of non-functions in the case of an ambiguous lookup. */
2053 void
2055 {
2059 }
2061 /* Get a (possibly) constrained template declaration for the
2062 purpose of ordering candidates. */
2063 static tree
2065 {
2071 }
2073 /* Among candidates having the same signature, return the
2074 most constrained or NULL_TREE if there is no best candidate.
2075 If the signatures of candidates vary (e.g., template
2076 specialization vs. member function), then there can be no
2077 most constrained.
2079 Note that we don't compare constraints on the functions
2080 themselves, but rather those of their templates. */
2081 static tree
2083 {
2084 // Try to find the best candidate in a first pass.
2087 {
2094 }
2096 // Verify that the champ is better than previous candidates.
2101 }
2104 }
2107 /* Returns the template (one of the functions given by TEMPLATE_ID)
2108 which can be specialized to match the indicated DECL with the
2109 explicit template args given in TEMPLATE_ID. The DECL may be
2110 NULL_TREE if none is available. In that case, the functions in
2111 TEMPLATE_ID are non-members.
2113 If NEED_MEMBER_TEMPLATE is nonzero the function is known to be a
2114 specialization of a member template.
2116 The TEMPLATE_COUNT is the number of references to qualifying
2117 template classes that appeared in the name of the function. See
2118 check_explicit_specialization for a more accurate description.
2120 TSK indicates what kind of template declaration (if any) is being
2121 declared. TSK_TEMPLATE indicates that the declaration given by
2122 DECL, though a FUNCTION_DECL, has template parameters, and is
2123 therefore a template function.
2125 The template args (those explicitly specified and those deduced)
2126 are output in a newly created vector *TARGS_OUT.
2128 If it is impossible to determine the result, an error message is
2129 issued. The error_mark_node is returned to indicate failure. */
2131 static tree
2133 tree decl,
2137 tmpl_spec_kind tsk)
2138 {
2139 tree fns;
2140 tree targs;
2141 tree explicit_targs;
2144 /* A TREE_LIST of templates of which DECL may be a specialization.
2145 The TREE_VALUE of each node is a TEMPLATE_DECL. The
2146 corresponding TREE_PURPOSE is the set of template arguments that,
2147 when used to instantiate the template, would produce a function
2148 with the signature of DECL. */
2158 /* We shouldn't be specializing a member template of an
2159 unspecialized class template; we already gave an error in
2160 check_specialization_scope, now avoid crashing. */
2164 {
2167 }
2175 /* Check for baselinks. */
2180 {
2184 }
2186 {
2189 }
2191 /* Count the number of template headers specified for this
2192 specialization. */
2203 {
2206 tf_warning_or_error);
2210 }
2212 {
2216 {
2217 tree decl_arg_types;
2218 tree fn_arg_types;
2220 /* In case of explicit specialization, we need to check if
2221 the number of template headers appearing in the specialization
2222 is correct. This is usually done in check_explicit_specialization,
2223 but the check done there cannot be exhaustive when specializing
2224 member functions. Consider the following code:
2226 template <> void A<int>::f(int);
2227 template <> template <> void A<int>::f(int);
2229 Assuming that A<int> is not itself an explicit specialization
2230 already, the first line specializes "f" which is a non-template
2231 member function, whilst the second line specializes "f" which
2232 is a template member function. So both lines are syntactically
2233 correct, and check_explicit_specialization does not reject
2234 them.
2236 Here, we can do better, as we are matching the specialization
2237 against the declarations. We count the number of template
2238 headers, and we check if they match TEMPLATE_COUNT + 1
2239 (TEMPLATE_COUNT is the number of qualifying template classes,
2240 plus there must be another header for the member template
2241 itself).
2243 Notice that if header_count is zero, this is not a
2244 specialization but rather a template instantiation, so there
2245 is no check we can perform here. */
2247 {
2250 }
2252 /* Check that the number of template arguments at the
2253 innermost level for DECL is the same as for FN. */
2261 /* DECL might be a specialization of FN. */
2265 /* For a non-static member function, we need to make sure
2266 that the const qualification is the same. Since
2267 get_bindings does not try to merge the "this" parameter,
2268 we must do the comparison explicitly. */
2270 {
2275 /* And the ref-qualification. */
2279 }
2281 /* Skip the "this" parameter and, for constructors of
2282 classes with virtual bases, the VTT parameter. A
2283 full specialization of a constructor will have a VTT
2284 parameter, but a template never will. */
2285 decl_arg_types
2287 fn_arg_types
2290 /* Function templates cannot be specializations; there are
2291 no partial specializations of functions. Therefore, if
2292 the type of DECL does not match FN, there is no
2293 match.
2295 Note that it should never be the case that we have both
2296 candidates added here, and for regular member functions
2297 below. */
2299 {
2301 current_template_parms))
2314 {
2315 /* C++20 CA104: Substitute directly into the
2316 constraint-expression. */
2322 }
2326 }
2328 /* See whether this function might be a specialization of this
2329 template. Suppress access control because we might be trying
2330 to make this specialization a friend, and we have already done
2331 access control for the declaration of the specialization. */
2337 /* We cannot deduce template arguments that when used to
2338 specialize TMPL will produce DECL. */
2342 /* We deduced something involving 'auto', which isn't a valid
2343 template argument. */
2346 /* Save this template, and the arguments deduced. */
2348 }
2350 /* FN is an ordinary member function, and we need a
2351 specialization of a member template. */
2352 ;
2354 /* We can get IDENTIFIER_NODEs here in certain erroneous
2355 cases. */
2356 ;
2358 /* This is just an ordinary non-member function. Nothing can
2359 be a specialization of that. */
2360 ;
2362 /* Cannot specialize functions that are created implicitly. */
2363 ;
2364 else
2365 {
2366 tree decl_arg_types;
2368 /* This is an ordinary member function. However, since
2369 we're here, we can assume its enclosing class is a
2370 template class. For example,
2372 template <typename T> struct S { void f(); };
2373 template <> void S<int>::f() {}
2375 Here, S<int>::f is a non-template, but S<int> is a
2376 template class. If FN has the same type as DECL, we
2377 might be in business. */
2380 /* Its enclosing class is an explicit specialization
2381 of a template class. This is not a candidate. */
2386 /* The return types differ. */
2389 /* Adjust the type of DECL in case FN is a static member. */
2396 decl_arg_types))
2404 // If the deduced arguments do not satisfy the constraints,
2405 // this is not a candidate.
2409 // Add the candidate.
2411 }
2412 }
2415 {
2416 /* We have:
2418 [temp.expl.spec]
2420 It is possible for a specialization with a given function
2421 signature to be instantiated from more than one function
2422 template. In such cases, explicit specification of the
2423 template arguments must be used to uniquely identify the
2424 function template specialization being specialized.
2426 Note that here, there's no suggestion that we're supposed to
2427 determine which of the candidate templates is most
2428 specialized. However, we, also have:
2430 [temp.func.order]
2432 Partial ordering of overloaded function template
2433 declarations is used in the following contexts to select
2434 the function template to which a function template
2435 specialization refers:
2437 -- when an explicit specialization refers to a function
2438 template.
2440 So, we do use the partial ordering rules, at least for now.
2441 This extension can only serve to make invalid programs valid,
2442 so it's safe. And, there is strong anecdotal evidence that
2443 the committee intended the partial ordering rules to apply;
2444 the EDG front end has that behavior, and John Spicer claims
2445 that the committee simply forgot to delete the wording in
2446 [temp.expl.spec]. */
2449 {
2452 }
2453 }
2455 // Concepts allows multiple declarations of member functions
2456 // with the same signature. Like above, we need to rely on
2457 // on the partial ordering of those candidates to determine which
2458 // is the best.
2460 {
2462 {
2465 }
2466 }
2469 {
2474 "saw %d %<template<>%>, need %d for "
2479 }
2483 {
2489 }
2491 /* We have one, and exactly one, match. */
2493 {
2497 /* Propagate the candidate's constraints to the declaration. */
2501 /* DECL is a re-declaration or partial instantiation of a template
2502 function. */
2505 /* It was a specialization of an ordinary member function in a
2506 template class. */
2508 }
2510 /* It was a specialization of a template. */
2514 /* Propagate the template's constraints to the declaration. */
2519 }
2521 /* Returns a chain of parameter types, exactly like the SPEC_TYPES,
2522 but with the default argument values filled in from those in the
2523 TMPL_TYPES. */
2525 static tree
2527 tree tmpl_types)
2528 {
2529 tree new_spec_types;
2537 /* Substitute into the rest of the list. */
2538 new_spec_types =
2542 /* Add the default argument for this parameter. */
2545 new_spec_types);
2546 }
2548 /* DECL is an explicit specialization. Replicate default arguments
2549 from the template it specializes. (That way, code like:
2551 template <class T> void f(T = 3);
2552 template <> void f(double);
2553 void g () { f (); }
2555 works, as required.) An alternative approach would be to look up
2556 the correct default arguments at the call-site, but this approach
2557 is consistent with how implicit instantiations are handled. */
2559 static void
2561 {
2562 tree tmpl;
2563 tree spec_types;
2564 tree tmpl_types;
2565 tree new_spec_types;
2566 tree old_type;
2567 tree new_type;
2568 tree t;
2573 /* See if there's anything we need to do. */
2586 {
2587 /* Remove the this pointer, but remember the object's type for
2588 CV quals. */
2594 {
2595 /* DECL may contain more parameters than TMPL due to the extra
2596 in-charge parameter in constructors and destructors. */
2599 }
2601 {
2604 }
2605 }
2607 /* Compute the merged default arguments. */
2608 new_spec_types =
2611 /* Compute the new FUNCTION_TYPE. */
2613 {
2617 new_spec_types);
2620 /* Put the in-charge parameter back. */
2623 new_spec_types);
2627 new_spec_types);
2628 }
2629 else
2631 new_spec_types);
2637 }
2639 /* Return the number of template headers we expect to see for a definition
2640 or specialization of CTYPE or one of its non-template members. */
2642 int
2644 {
2648 {
2649 /* You're supposed to have one `template <...>' for every
2650 template class, but you don't need one for a full
2651 specialization. For example:
2653 template <class T> struct S{};
2654 template <> struct S<int> { void f(); };
2655 void S<int>::f () {}
2657 is correct; there shouldn't be a `template <>' for the
2658 definition of `S<int>::f'. */
2660 /* If CTYPE does not have template information of any
2661 kind, then it is not a template, nor is it nested
2662 within a template. */
2670 }
2673 }
2675 /* Do a simple sanity check on the template headers that precede the
2676 variable declaration DECL. */
2678 void
2680 {
2685 {
2688 "variable templates only available with "
2691 // Namespace-scope variable templates should have a template header.
2693 }
2695 {
2696 auto_diagnostic_group d;
2698 "too many template headers for %qD "
2704 "members of an explicitly specialized class are defined "
2706 }
2707 }
2709 /* An explicit specialization whose declarator-id or class-head-name is not
2710 qualified shall be declared in the nearest enclosing namespace of the
2711 template, or, if the namespace is inline (7.3.1), any namespace from its
2712 enclosing namespace set.
2714 If the name declared in the explicit instantiation is an unqualified name,
2715 the explicit instantiation shall appear in the namespace where its template
2716 is declared or, if that namespace is inline (7.3.1), any namespace from its
2717 enclosing namespace set. */
2719 void
2721 {
2726 {
2732 /* This was allowed in C++98, so only pedwarn. */
2734 "outside its namespace must use a nested-name-"
2736 }
2737 }
2739 /* Warn for a template specialization SPEC that is missing some of a set
2740 of function or type attributes that the template TEMPL is declared with.
2741 ATTRLIST is a list of additional attributes that SPEC should be taken
2742 to ultimately be declared with. */
2744 static void
2746 {
2750 /* Avoid warning if the difference between the primary and
2751 the specialization is not in one of the attributes below. */
2755 };
2757 /* Put together a list of the black listed attributes that the primary
2758 template is declared with that the specialization is not, in case
2759 it's not apparent from the most recent declaration of the primary. */
2760 pretty_printer str;
2767 auto_diagnostic_group d;
2770 spec))
2776 }
2778 /* Check to see if the function just declared, as indicated in
2779 DECLARATOR, and in DECL, is a specialization of a function
2780 template. We may also discover that the declaration is an explicit
2781 instantiation at this point.
2783 Returns DECL, or an equivalent declaration that should be used
2784 instead if all goes well. Issues an error message if something is
2785 amiss. Returns error_mark_node if the error is not easily
2786 recoverable.
2788 FLAGS is a bitmask consisting of the following flags:
2790 2: The function has a definition.
2791 4: The function is a friend.
2793 The TEMPLATE_COUNT is the number of references to qualifying
2794 template classes that appeared in the name of the function. For
2795 example, in
2797 template <class T> struct S { void f(); };
2798 void S<int>::f();
2800 the TEMPLATE_COUNT would be 1. However, explicitly specialized
2801 classes are not counted in the TEMPLATE_COUNT, so that in
2803 template <class T> struct S {};
2804 template <> struct S<int> { void f(); }
2805 template <> void S<int>::f();
2807 the TEMPLATE_COUNT would be 0. (Note that this declaration is
2808 invalid; there should be no template <>.)
2810 If the function is a specialization, it is marked as such via
2811 DECL_TEMPLATE_SPECIALIZATION. Furthermore, its DECL_TEMPLATE_INFO
2812 is set up correctly, and it is added to the list of specializations
2813 for that template. */
2815 tree
2817 tree decl,
2820 tree attrlist)
2821 {
2830 tmpl_spec_kind tsk;
2833 {
2836 else
2838 }
2839 else
2843 {
2846 {
2849 }
2853 {
2855 /* This could be something like:
2857 template <class T> void f(T);
2858 class S { friend void f<>(int); } */
2860 else
2861 {
2862 /* This case handles bogus declarations like template <>
2863 template <class T> void f<int>(); */
2867 declarator);
2869 }
2870 }
2874 /* The error has already been reported in
2875 check_specialization_scope. */
2881 /* Fall through. */
2894 decl);
2897 else
2901 /* Fall through. */
2907 /* In cases like template<> constexpr bool v = true;
2908 We'll give an error in check_template_variable. */
2914 else
2920 {
2921 /* This case handles bogus declarations like template <>
2922 template <class T> void f<int>(); */
2927 declarator);
2929 {
2930 /* Partial specialization of variable template. */
2934 }
2937 "non-type partial specialization %qE "
2939 else
2941 "non-class, non-variable partial specialization %qE "
2944 ok:;
2945 }
2948 /* This is a specialization of a member template, without
2949 specialization the containing class. Something like:
2951 template <class T> struct S {
2952 template <class U> void f (U);
2953 };
2954 template <> template <class U> void S<int>::f(U) {}
2956 That's a specialization -- but of the entire template. */
2962 }
2965 /* This doesn't apply to variable templates. */
2967 {
2971 {
2975 }
2976 }
2979 {
2985 /* Make sure that the declarator is a TEMPLATE_ID_EXPR. */
2987 {
2988 tree fns;
2993 else
2994 {
2995 /* If there is no class context, the explicit instantiation
2996 must be at namespace scope. */
2999 /* Find the namespace binding, using the declaration
3000 context. */
3004 {
3005 /* If lookup fails, look for a friend declaration so we can
3006 give a better diagnostic. */
3007 fns = (lookup_qualified_name
3012 }
3015 {
3018 }
3019 }
3022 }
3028 {
3030 /* A specialization in class scope. This is invalid,
3031 but the error will already have been flagged by
3032 check_specialization_scope. */
3034 else
3035 {
3036 /* It's not valid to write an explicit instantiation in
3037 class scope, e.g.:
3039 class C { template void f(); }
3041 This case is caught by the parser. However, on
3042 something like:
3044 template class C { void f(); };
3046 (which is invalid) we can get here. The error will be
3047 issued later. */
3048 ;
3049 }
3052 }
3055 {
3056 // We'll match variable templates in start_decl.
3060 /* Find the list of functions in ctype that have the same
3061 name as the declared function. */
3065 {
3069 {
3070 /* From [temp.expl.spec]:
3072 If such an explicit specialization for the member
3073 of a class template names an implicitly-declared
3074 special member function (clause _special_), the
3075 program is ill-formed.
3077 Similar language is found in [temp.explicit]. */
3080 }
3083 }
3085 /* For a type-conversion operator, We might be looking for
3086 `operator int' which will be a specialization of
3087 `operator T'. Grab all the conversion operators, and
3088 then select from them. */
3093 {
3096 }
3097 else
3099 }
3101 /* Figure out what exactly is being specialized at this point.
3102 Note that for an explicit instantiation, even one for a
3103 member function, we cannot tell a priori whether the
3104 instantiation is for a member template, or just a member
3105 function of a template class. Even if a member template is
3106 being instantiated, the member template arguments may be
3107 elided if they can be deduced from the rest of the
3108 declaration. */
3111 member_specialization,
3112 template_count,
3113 tsk);
3116 /* We couldn't figure out what this declaration was
3117 specializing. */
3119 else
3120 {
3122 {
3123 auto_diagnostic_group d;
3125 "friend declaration %qD is not visible to "
3129 }
3138 {
3139 /* We don't set DECL_EXPLICIT_INSTANTIATION here; that
3140 is done by do_decl_instantiation later. */
3146 {
3147 /* If TMPL is not the most general template (for
3148 example, if TMPL is a friend template that is
3149 injected into namespace scope), then there will
3150 be too many levels of TARGS. Remove some of them
3151 here. */
3153 tree new_targs;
3160 }
3163 }
3165 /* If we thought that the DECL was a member function, but it
3166 turns out to be specializing a static member function,
3167 make DECL a static member function as well. */
3173 /* If this is a specialization of a member template of a
3174 template class, we want to return the TEMPLATE_DECL, not
3175 the specialization of it. */
3177 {
3182 {
3183 tree parm;
3187 /* We want to use the argument list specified in the
3188 definition, not in the original declaration. */
3193 }
3198 }
3200 /* Set up the DECL_TEMPLATE_INFO for DECL. */
3206 /* Inherit default function arguments from the template
3207 DECL is specializing. */
3211 /* This specialization has the same protection as the
3212 template it specializes. */
3216 /* 7.1.1-1 [dcl.stc]
3218 A storage-class-specifier shall not be specified in an
3219 explicit specialization...
3221 The parser rejects these, so unless action is taken here,
3222 explicit function specializations will always appear with
3223 global linkage.
3225 The action recommended by the C++ CWG in response to C++
3226 defect report 605 is to make the storage class and linkage
3227 of the explicit specialization match the templated function:
3229 http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#605
3230 */
3232 {
3236 /* A concept cannot be specialized. */
3238 {
3240 gen_tmpl);
3242 }
3244 /* This specialization has the same linkage and visibility as
3245 the function template it specializes. */
3248 {
3251 }
3254 {
3257 }
3258 }
3260 /* If DECL is a friend declaration, declared using an
3261 unqualified name, the namespace associated with DECL may
3262 have been set incorrectly. For example, in:
3264 template <typename T> void f(T);
3265 namespace N {
3266 struct S { friend void f<int>(int); }
3267 }
3269 we will have set the DECL_CONTEXT for the friend
3270 declaration to N, rather than to the global namespace. */
3275 /* This is not really a declaration of a specialization.
3276 It's just the name of an instantiation. But, it's not
3277 a request for an instantiation, either. */
3280 /* A specialization is not necessarily COMDAT. */
3286 /* If this is a full specialization, register it so that we can find
3287 it again. Partial specializations will be registered in
3288 process_partial_specialization. */
3290 {
3295 }
3297 /* If this is a specialization, splice any contracts that may have
3298 been inherited from the template, removing them. */
3302 /* A 'structor should already have clones. */
3308 }
3309 }
3312 }
3314 /* Returns 1 iff PARMS1 and PARMS2 are identical sets of template
3315 parameters. These are represented in the same format used for
3316 DECL_TEMPLATE_PARMS. */
3318 int
3320 {
3335 {
3339 /* If either of the template parameters are invalid, assume
3340 they match for the sake of error recovery. */
3353 }
3356 }
3358 /* Returns true if two template parameters are declared with
3359 equivalent constraints. */
3361 static bool
3363 {
3371 }
3373 /* Returns true when two template parameters are equivalent. */
3375 static bool
3377 {
3381 /* If either of the template parameters are invalid, assume
3382 they match for the sake of error recovery. */
3386 /* ... they declare parameters of the same kind. */
3390 /* ... one parameter was introduced by a parameter declaration, then
3391 both are. This case arises as a result of eagerly rewriting declarations
3392 during parsing. */
3397 /* ... if either declares a pack, they both do. */
3402 {
3403 /* ... if they declare non-type parameters, the types are equivalent. */
3406 }
3408 {
3409 /* ... if they declare template template parameters, their template
3410 parameter lists are equivalent. */
3413 }
3415 /* ... if they are declared with a qualified-concept name, they both
3416 are, and those names are equivalent. */
3418 }
3420 /* Returns true if two template parameters lists are equivalent.
3421 Two template parameter lists are equivalent if they have the
3422 same length and their corresponding parameters are equivalent.
3424 PARMS1 and PARMS2 are TREE_LISTs containing TREE_VECs: the
3425 data structure returned by DECL_TEMPLATE_PARMS.
3427 This is generally the same implementation as comp_template_parms
3428 except that it also the concept names and arguments used to
3429 introduce parameters. */
3431 static bool
3433 {
3444 {
3449 }
3452 }
3454 /* Return true if the requires-clause of the template parameter lists are
3455 equivalent and false otherwise. */
3456 static bool
3458 {
3466 }
3468 /* Returns true if two template heads are equivalent. 17.6.6.1p6:
3469 Two template heads are equivalent if their template parameter
3470 lists are equivalent and their requires clauses are equivalent.
3472 In pre-C++20, this is equivalent to calling comp_template_parms
3473 for the template parameters of TMPL1 and TMPL2. */
3475 bool
3477 {
3481 /* Don't change the matching rules for pre-C++20. */
3485 /* ... have the same number of template parameters, and their
3486 corresponding parameters are equivalent. */
3490 /* ... if either has a requires-clause, they both do and their
3491 corresponding constraint-expressions are equivalent. */
3493 }
3495 /* Determine whether PARM is a parameter pack. */
3497 bool
3499 {
3500 /* Determine if we have a non-type template parameter pack. */
3507 /* If this is a list of template parameters, we could get a
3508 TYPE_DECL or a TEMPLATE_DECL. */
3512 /* Otherwise it must be a type template parameter. */
3516 }
3518 /* Determine if T is a function parameter pack. */
3520 bool
3522 {
3526 }
3528 /* Return the function template declaration of PRIMARY_FUNC_TMPL_INST.
3529 PRIMARY_FUNC_TMPL_INST is a primary function template instantiation. */
3531 tree
3533 {
3540 }
3542 /* Return true iff the function parameter PARAM_DECL was expanded
3543 from the function parameter pack PACK. */
3545 bool
3547 {
3552 /* The parameter pack and its pack arguments have the same
3553 DECL_PARM_INDEX. */
3555 }
3557 /* Determine whether ARGS describes a variadic template args list,
3558 i.e., one that is terminated by a template argument pack. */
3560 static bool
3562 {
3564 tree last_parm;
3578 }
3580 /* Generate a new name for the parameter pack name NAME (an
3581 IDENTIFIER_NODE) that incorporates its */
3583 static tree
3585 {
3586 /* Munge the name to include the parameter index. */
3587 #define NUMBUF_LEN 128
3601 }
3603 /* Return true if T is a primary function, class or alias template
3604 specialization, not including the template pattern. */
3606 bool
3608 {
3624 }
3626 /* Return true if PARM is a template template parameter. */
3628 bool
3630 {
3632 }
3634 /* Return true iff PARM is a DECL representing a type template
3635 parameter. */
3637 bool
3639 {
3644 }
3646 /* Return the template parameters of T if T is a
3647 primary template instantiation, NULL otherwise. */
3649 tree
3651 {
3656 parms = INNERMOST_TEMPLATE_PARMS
3660 }
3662 /* Returns the template arguments of T if T is a template instantiation,
3663 NULL otherwise. */
3665 tree
3667 {
3675 }
3677 /* Return the argument pack elements of T if T is a template argument pack,
3678 NULL otherwise. */
3680 tree
3682 {
3688 }
3690 /* In an ARGUMENT_PACK_SELECT, the actual underlying argument that the
3691 ARGUMENT_PACK_SELECT represents. */
3693 static tree
3695 {
3699 /* If the selected argument is an expansion E, that most likely means we were
3700 called from gen_elem_of_pack_expansion_instantiation during the
3701 substituting of an argument pack (of which the Ith element is a pack
3702 expansion, where I is ARGUMENT_PACK_SELECT_INDEX) into a pack expansion.
3703 In this case, the Ith element resulting from this substituting is going to
3704 be a pack expansion, which pattern is the pattern of E. Let's return the
3705 pattern of E, and gen_elem_of_pack_expansion_instantiation will build the
3706 resulting pack expansion from it. */
3708 {
3709 /* Make sure we aren't throwing away arg info. */
3712 }
3715 }
3717 /* Return a modification of ARGS that's suitable for preserving inside a hash
3718 table. In particular, this replaces each ARGUMENT_PACK_SELECT with its
3719 underlying argument. ARGS is copied (upon modification) iff COW_P. */
3721 static tree
3723 {
3728 {
3730 tree r;
3737 else
3740 {
3742 {
3745 }
3747 }
3748 }
3751 }
3753 /* True iff FN is a function representing a built-in variadic parameter
3754 pack. */
3756 bool
3758 {
3768 }
3770 /* True iff CALL is a call to a function representing a built-in variadic
3771 parameter pack. */
3773 static bool
3775 {
3779 }
3781 /* Return a TREE_VEC for the expansion of __integer_pack(HI). */
3783 static tree
3785 tree in_decl)
3786 {
3791 {
3793 {
3796 }
3801 }
3802 else
3803 {
3808 /* Calculate the largest value of len that won't make the size of the vec
3809 overflow an int. The compiler will exceed resource limits long before
3810 this, but it seems a decent place to diagnose. */
3814 {
3818 max);
3820 }
3828 }
3829 }
3831 /* Return a TREE_VEC for the expansion of built-in template parameter pack
3832 CALL. */
3834 static tree
3836 tree in_decl)
3837 {
3847 }
3849 /* Return true if the tree T has the extra args mechanism for
3850 avoiding partial instantiation. */
3852 static bool
3854 {
3859 }
3861 /* Structure used to track the progress of find_parameter_packs_r. */
3862 struct find_parameter_pack_data
3863 {
3864 /* TREE_LIST that will contain all of the parameter packs found by
3865 the traversal. */
3868 /* Set of AST nodes that have been visited by the traversal. */
3871 /* True iff we're making a type pack expansion. */
3874 /* True iff we found a subtree that has the extra args mechanism. */
3876 };
3878 /* Identifies all of the argument packs that occur in a template
3879 argument and appends them to the TREE_LIST inside DATA, which is a
3880 find_parameter_pack_data structure. This is a subroutine of
3881 make_pack_expansion and uses_parameter_packs. */
3882 static tree
3884 {
3890 #define WALK_SUBTREE(NODE) \
3891 cp_walk_tree (&(NODE), &find_parameter_packs_r, \
3892 ppd, ppd->visited) \
3894 /* Don't look through typedefs; we are interested in whether a
3895 parameter pack is actually written in the expression/type we're
3896 looking at, not the target type. */
3898 {
3899 /* But do look at arguments for an alias template. */
3906 }
3908 /* Identify whether this is a parameter pack or not. */
3910 {
3918 /* FALLTHRU */
3920 /* If the placeholder appears in the decl-specifier-seq of a function
3921 parameter pack (14.6.3), or the type-specifier-seq of a type-id that
3922 is a pack expansion, the invented template parameter is a template
3923 parameter pack. */
3933 {
3934 /* We don't want to walk into the type of a PARM_DECL,
3935 because we don't want to see the type parameter pack. */
3938 }
3943 {
3944 /* We don't want to walk into the type of a variadic capture proxy,
3945 because we don't want to see the type parameter pack. */
3948 }
3950 {
3952 find_parameter_packs_r,
3955 }
3967 /* Not a parameter pack. */
3969 }
3972 {
3973 /* Add this parameter pack to the list. */
3975 }
3984 /* This switch statement will return immediately if we don't find a
3985 parameter pack. ??? Should some of these be in cp_walk_subtrees? */
3987 {
3989 /* Check the template itself. */
3995 {
3997 /* Ignore the declaration of a capture proxy for a parameter pack. */
4001 /* Since we stop at typedefs above, we need to look through them at
4002 the point of the DECL_EXPR. */
4006 }
4033 {
4034 /* Since we defer implicit capture, look in the parms and body. */
4041 }
4044 {
4045 /* When traversing a DECLTYPE_TYPE_EXPR, we need to set
4046 type_pack_expansion_p to false so that any placeholders
4047 within the expression don't get marked as parameter packs. */
4055 }
4064 /* Don't walk into IF_STMT_EXTRA_ARGS. */
4071 {
4072 /* Local class, need to look through the whole definition.
4073 TYPE_BINFO might be unset for a partial instantiation. */
4078 }
4079 else
4080 /* Enum, look at the values. */
4094 }
4096 #undef WALK_SUBTREE
4099 }
4101 /* Determines if the expression or type T uses any parameter packs. */
4102 tree
4104 {
4113 }
4115 /* Turn ARG, which may be an expression, type, or a TREE_LIST
4116 representation a base-class initializer into a parameter pack
4117 expansion. If all goes well, the resulting node will be an
4118 EXPR_PACK_EXPANSION, TYPE_PACK_EXPANSION, or TREE_LIST,
4119 respectively. */
4120 tree
4122 {
4123 tree result;
4132 {
4133 /* A TREE_LIST with a non-null TREE_PURPOSE is for a base
4134 class initializer. In this case, the TREE_PURPOSE will be a
4135 _TYPE node (representing the base class expansion we're
4136 initializing) and the TREE_VALUE will be a TREE_LIST
4137 containing the initialization arguments.
4139 The resulting expansion looks somewhat different from most
4140 expansions. Rather than returning just one _EXPANSION, we
4141 return a TREE_LIST whose TREE_PURPOSE is a
4142 TYPE_PACK_EXPANSION containing the bases that will be
4143 initialized. The TREE_VALUE will be identical to the
4144 original TREE_VALUE, which is a list of arguments that will
4145 be passed to each base. We do not introduce any new pack
4146 expansion nodes into the TREE_VALUE (although it is possible
4147 that some already exist), because the TREE_PURPOSE and
4148 TREE_VALUE all need to be expanded together with the same
4149 _EXPANSION node. Note that the TYPE_PACK_EXPANSION in the
4150 resulting TREE_PURPOSE will mention the parameter packs in
4151 both the bases and the arguments to the bases. */
4152 tree purpose;
4153 tree value;
4156 /* Determine which parameter packs will be used by the base
4157 class expansion. */
4166 {
4169 arg);
4172 }
4175 {
4176 /* Collect the sets of parameter packs used in each of the
4177 initialization arguments. */
4179 {
4180 /* Determine which parameter packs will be expanded in this
4181 argument. */
4184 }
4185 }
4189 /* Create the pack expansion type for the base type. */
4195 /* Just use structural equality for these TYPE_PACK_EXPANSIONS;
4196 they will rarely be compared to anything. */
4200 }
4205 /* Build the PACK_EXPANSION_* node. */
4206 result = for_types
4211 {
4212 /* Propagate type and const-expression information. */
4215 /* Mark this read now, since the expansion might be length 0. */
4217 }
4218 else
4219 /* Just use structural equality for these TYPE_PACK_EXPANSIONS;
4220 they will rarely be compared to anything. */
4223 /* Determine which parameter packs will be expanded. */
4230 /* Make sure we found some parameter packs. */
4232 {
4234 {
4237 else
4239 }
4241 }
4246 /* If the pattern of this pack expansion contains a subtree that has
4247 the extra args mechanism for avoiding partial instantiation, then
4248 force this pack expansion to also use extra args. Otherwise
4249 partial instantiation of this pack expansion may not lower the
4250 level of some parameter packs within the pattern, which would
4251 confuse tsubst_pack_expansion later (PR101764). */
4255 }
4257 /* Checks T for any "bare" parameter packs, which have not yet been
4258 expanded, and issues an error if any are found. This operation can
4259 only be done on full expressions or types (e.g., an expression
4260 statement, "if" condition, etc.), because we could have expressions like:
4262 foo(f(g(h(args)))...)
4264 where "args" is a parameter pack. check_for_bare_parameter_packs
4265 should not be called for the subexpressions args, h(args),
4266 g(h(args)), or f(g(h(args))), because we would produce erroneous
4267 error messages.
4269 Returns TRUE and emits an error if there were bare parameter packs,
4270 returns FALSE otherwise. */
4271 bool
4273 {
4295 /* It's OK for a lambda to have an unexpanded parameter pack from the
4296 containing context, but do complain about unexpanded capture packs. */
4302 {
4303 /* We're in a lambda, but it isn't the innermost class.
4304 This should work, but currently doesn't. */
4307 }
4312 {
4318 }
4321 {
4324 {
4335 else
4340 else
4344 }
4347 }
4350 }
4352 /* Expand any parameter packs that occur in the template arguments in
4353 ARGS. */
4354 tree
4356 {
4365 /* First, determine if we need to expand anything, and the number of
4366 slots we'll need. */
4368 {
4373 {
4377 else
4379 }
4380 else
4381 {
4383 num_result_args++;
4384 }
4385 }
4387 /* If no expansion is necessary, we're done. */
4391 /* Expand arguments. */
4394 non_default_args_count =
4397 {
4400 {
4407 }
4408 else
4409 {
4412 }
4413 }
4417 }
4419 /* Checks if DECL shadows a template parameter.
4421 [temp.local]: A template-parameter shall not be redeclared within its
4422 scope (including nested scopes).
4424 Emits an error and returns TRUE if the DECL shadows a parameter,
4425 returns FALSE otherwise. */
4427 bool
4429 {
4430 tree olddecl;
4432 /* If we're not in a template, we can't possibly shadow a template
4433 parameter. */
4437 /* Figure out what we're shadowing. */
4441 /* If there's no previous binding for this name, we're not shadowing
4442 anything, let alone a template parameter. */
4446 /* If we're not shadowing a template parameter, we're done. Note
4447 that OLDDECL might be an OVERLOAD (or perhaps even an
4448 ERROR_MARK), so we can't just blithely assume it to be a _DECL
4449 node. */
4453 /* We check for decl != olddecl to avoid bogus errors for using a
4454 name inside a class. We check TPFI to avoid duplicate errors for
4455 inline member templates. */
4461 /* Don't complain about the injected class name, as we've already
4462 complained about the class itself. */
4469 else
4474 }
4476 /* Return a new TEMPLATE_PARM_INDEX with the indicated INDEX, LEVEL,
4477 ORIG_LEVEL, DECL, and TYPE. */
4479 static tree
4483 tree decl,
4484 tree type)
4485 {
4496 }
4499 {
4501 {
4513 }
4516 {
4521 }
4522 };
4526 /* Find the canonical type parameter for the given template type
4527 parameter. Returns the canonical type parameter, which may be TYPE
4528 if no such parameter existed. */
4530 tree
4532 {
4540 }
4542 /* Return a TEMPLATE_PARM_INDEX, similar to INDEX, but whose
4543 TEMPLATE_PARM_LEVEL has been decreased by LEVELS. If such a
4544 TEMPLATE_PARM_INDEX already exists, it is returned; otherwise, a
4545 new one is created. */
4547 static tree
4549 tsubst_flags_t complain)
4550 {
4555 {
4560 type);
4575 /* Template template parameters need this. */
4578 {
4590 }
4592 /* Attach the TPI to the decl. */
4595 else
4597 }
4600 }
4602 /* Process information from new template parameter PARM and append it
4603 to the LIST being built. This new parameter is a non-type
4604 parameter iff IS_NON_TYPE is true. This new parameter is a
4605 parameter pack iff IS_PARAMETER_PACK is true. The location of PARM
4606 is in PARM_LOC. */
4608 tree
4611 {
4617 {
4627 }
4634 {
4640 {
4641 /* [temp.param]
4643 The top-level cv-qualifiers on the template-parameter are
4644 ignored when determining its type. */
4649 && !is_parameter_pack
4650 /* If we're in a nested template parameter list, the template
4651 template parameter could be a parameter pack. */
4653 {
4654 /* This template parameter is not a parameter pack, but it
4655 should be. Complain about "bare" parameter packs. */
4658 /* Recover by calling this a parameter pack. */
4660 }
4661 }
4663 /* A template parameter is not modifiable. */
4672 current_template_depth,
4677 }
4678 else
4679 {
4680 tree t;
4684 {
4686 /* This is for distinguishing between real templates and template
4687 template parameters */
4690 /* any_template_parm_r expects to be able to get the targs of a
4691 DECL_TEMPLATE_RESULT. */
4700 }
4701 else
4702 {
4704 /* parm is either IDENTIFIER_NODE or NULL_TREE. */
4707 }
4714 current_template_depth,
4718 }
4726 /* Build requirements for the type/template parameter.
4727 This must be done after SET_DECL_TEMPLATE_PARM_P or
4728 process_template_parm could fail. */
4735 /* Build the parameter node linking the parameter declaration,
4736 its default argument (if any), and its constraints (if any). */
4742 else
4746 }
4748 /* The end of a template parameter list has been reached. Process the
4749 tree list into a parameter vector, converting each parameter into a more
4750 useful form. Type parameters are saved as IDENTIFIER_NODEs, and others
4751 as PARM_DECLs. */
4753 tree
4755 {
4758 /* Pop the dummy parameter level and add the real one. We do not
4759 morph the dummy parameter in place, as it might have been
4760 captured by a (nested) template-template-parm. */
4763 current_template_parms
4768 {
4774 }
4779 }
4781 // Explicitly indicate the end of the template parameter list. We assume
4782 // that the current template parameters have been constructed and/or
4783 // managed explicitly, as when creating new template template parameters
4784 // from a shorthand constraint.
4785 void
4787 {
4789 }
4791 /* end_template_decl is called after a template declaration is seen. */
4793 void
4795 {
4801 /* This matches the pushlevel in begin_template_parm_list. */
4806 }
4808 /* Takes a TEMPLATE_PARM_P or DECL_TEMPLATE_PARM_P node or a TREE_LIST
4809 thereof, and converts it into an argument suitable to be passed to
4810 the type substitution functions. Note that if the TREE_LIST contains
4811 an error_mark node, the returned argument is error_mark_node. */
4813 tree
4815 {
4826 {
4830 else
4832 }
4838 {
4840 {
4841 /* Turn this argument into a TYPE_ARGUMENT_PACK
4842 with a single element, which expands T. */
4851 }
4852 }
4853 else
4854 {
4856 {
4857 /* Turn this argument into a NONTYPE_ARGUMENT_PACK
4858 with a single element, which expands T. */
4868 }
4869 else
4871 }
4873 }
4875 /* If T looks like a generic template argument produced by template_parm_to_arg,
4876 return the corresponding template parameter, otherwise return NULL_TREE. */
4878 static tree
4880 {
4885 {
4890 }
4897 else
4899 }
4901 /* Given a single level of template parameters (a TREE_VEC), return it
4902 as a set of template arguments. */
4904 tree
4906 {
4916 }
4918 /* Given a set of template parameters, return them as a set of template
4919 arguments. The template parameters are represented as a TREE_VEC, in
4920 the form documented in cp-tree.h for template arguments. */
4922 tree
4924 {
4925 tree header;
4930 /* If there is only one level of template parameters, we do not
4931 create a TREE_VEC of TREE_VECs. Instead, we return a single
4932 TREE_VEC containing the arguments. */
4937 {
4942 else
4944 }
4947 }
4949 /* Within the declaration of a template, return the currently active
4950 template parameters as an argument TREE_VEC. */
4952 static tree
4954 {
4956 }
4958 /* Return the fully generic arguments for of TMPL, i.e. what
4959 current_template_args would be while parsing it. */
4961 tree
4963 {
4968 /* DECL_TEMPLATE_RESULT doesn't have the arguments we want. For a template
4969 template parameter, it has no TEMPLATE_INFO; for a partial
4970 specialization, it has the arguments for the primary template, and we
4976 }
4978 /* Return the template arguments corresponding to the template parameters of
4979 DECL's enclosing scope. When DECL is a member of a partial specialization,
4980 this returns the arguments for the partial specialization as opposed to those
4981 for the primary template, which is the main difference between this function
4982 and simply using e.g. the TYPE_TI_ARGS of DECL's DECL_CONTEXT. */
4984 tree
4986 {
4998 }
5000 /* Update the declared TYPE by doing any lookups which were thought to be
5001 dependent, but are not now that we know the SCOPE of the declarator. */
5003 tree
5005 {
5016 /* Don't bother building up the args in this case. */
5018 {
5019 /* tsubst in the args corresponding to the template parameters,
5020 including auto if present. Most things will be unchanged, but
5021 make_typename_type and tsubst_qualified_id will resolve
5022 TYPENAME_TYPEs and SCOPE_REFs that were previously dependent. */
5025 tree pushed;
5027 {
5031 }
5036 }
5042 {
5045 else
5047 }
5049 }
5051 /* Return a TEMPLATE_DECL corresponding to DECL, using the indicated
5052 template PARMS and constraints, CONSTR. If MEMBER_TEMPLATE_P is true,
5053 the new template is a member template. */
5055 static tree
5057 {
5069 /* Propagate module information from the decl. */
5073 }
5075 struct template_parm_data
5076 {
5077 /* The level of the template parameters we are currently
5078 processing. */
5081 /* The index of the specialization argument we are currently
5082 processing. */
5085 /* An array whose size is the number of template parameters. The
5086 elements are nonzero if the parameter has been used in any one
5087 of the arguments processed so far. */
5090 /* An array whose size is the number of template arguments. The
5091 elements are nonzero if the argument makes use of template
5092 parameters of this level. */
5094 };
5096 /* Subroutine of push_template_decl used to see if each template
5097 parameter in a partial specialization is used in the explicit
5098 argument list. If T is of the LEVEL given in DATA (which is
5099 treated as a template_parm_data*), then DATA->PARMS is marked
5100 appropriately. */
5102 static int
5104 {
5112 {
5115 }
5117 /* In C++17 the type of a non-type argument is a deduced context. */
5122 data,
5123 NULL,
5126 /* Return zero so that for_each_template_parm will continue the
5127 traversal of the tree; we want to mark *every* template parm. */
5129 }
5131 /* Process the partial specialization DECL. */
5133 static tree
5135 {
5142 tree inner_parms;
5143 tree inst;
5153 /* A concept cannot be specialized. */
5155 {
5158 }
5163 /* We check that each of the template parameters given in the
5164 partial specialization is used in the argument list to the
5165 specialization. For example:
5167 template <class T> struct S;
5168 template <class T> struct S<T*>;
5170 The second declaration is OK because `T*' uses the template
5171 parameter T, whereas
5173 template <class T> struct S<int>;
5175 is no good. Even trickier is:
5177 template <class T>
5178 struct S1
5179 {
5180 template <class U>
5181 struct S2;
5182 template <class U>
5183 struct S2<T>;
5184 };
5186 The S2<T> declaration is actually invalid; it is a
5187 full-specialization. Of course,
5189 template <class U>
5190 struct S2<T (*)(U)>;
5192 or some such would have been OK. */
5200 {
5205 NULL,
5207 }
5210 {
5211 /* One of the template parms was not used in a deduced context in the
5212 specialization. */
5214 {
5218 }
5222 }
5227 /* [temp.class.spec]
5229 The argument list of the specialization shall not be identical to
5230 the implicit argument list of the primary template. */
5231 tree main_args
5234 && (!flag_concepts
5236 {
5239 "any template arguments; to define the primary template, "
5241 else
5243 "template arguments and is not more constrained than "
5244 "the primary template; to define the primary template, "
5247 }
5249 /* A partial specialization that replaces multiple parameters of the
5250 primary template with a pack expansion is less specialized for those
5251 parameters. */
5253 {
5255 "primary template because it replaces multiple parameters "
5258 /* Avoid crash in process_partial_specialization. */
5260 }
5263 {
5266 /* Avoid crash below. */
5268 }
5270 /* If we aren't in a dependent class, we can actually try deduction. */
5272 /* FIXME we should be able to handle a partial specialization of a
5273 partial instantiation, but currently we can't (c++/41727). */
5276 {
5277 auto_diagnostic_group d;
5280 decl))
5282 maintmpl);
5283 }
5285 /* [temp.spec.partial]
5287 The type of a template parameter corresponding to a specialized
5288 non-type argument shall not be dependent on a parameter of the
5289 specialization.
5291 Also, we verify that pack expansions only occur at the
5292 end of the argument list. */
5295 {
5302 {
5303 /* Extract the arguments from the argument pack. We'll be
5304 iterating over these in the following loop. */
5307 }
5310 {
5312 /* Get the Jth argument in the parameter pack. */
5316 {
5317 /* Pack expansions must come at the end of the
5318 argument list. */
5321 {
5325 else
5328 }
5329 }
5332 /* We only care about the pattern. */
5338 /* This next two lines are the `argument expression is not just a
5339 simple identifier' condition and also the `specialized
5340 non-type argument' bit. */
5345 {
5346 /* Look at the corresponding template parameter,
5347 marking which template parameters its type depends
5348 upon. */
5352 {
5353 /* We haven't yet initialized TPD2. Do so now. */
5355 /* The number of parameters here is the number in the
5356 main template, which, as checked in the assertion
5357 above, is NARGS. */
5361 }
5363 /* Mark the template parameters. But this time, we're
5364 looking for the template parameters of the main
5365 template, not in the specialization. */
5372 NULL,
5376 {
5377 /* The type depended on some template parameters.
5378 If they are fully specialized in the
5379 specialization, that's OK. */
5388 "type %qT of template argument %qE depends "
5390 "type %qT of template argument %qE depends "
5392 type,
5393 arg);
5394 }
5395 }
5396 }
5397 }
5399 /* We should only get here once. */
5403 // Build the template decl.
5410 /* Give template template parms a DECL_CONTEXT of the template
5411 for which they are a parameter. */
5413 {
5417 }
5420 /* We didn't register this in check_explicit_specialization so we could
5421 wait until the constraints were set. */
5423 else
5430 /* Link the DECL_TEMPLATE_RESULT back to the partial TEMPLATE_DECL. */
5436 {
5442 {
5451 "declaration of %qD ambiguates earlier template "
5455 "partial specialization of %qD after instantiation "
5457 }
5458 }
5461 }
5463 /* PARM is a template parameter of some form; return the corresponding
5464 TEMPLATE_PARM_INDEX. */
5466 static tree
5468 {
5481 }
5483 /* Subroutine of fixed_parameter_pack_p below. Look for any template
5484 parameter packs used by the template parameter PARM. */
5486 static void
5488 {
5489 /* A type parm can't refer to another parm. */
5493 {
5497 }
5503 {
5507 else
5509 }
5510 }
5512 /* PARM is a template parameter pack. Return any parameter packs used in
5513 its type or the type of any of its template parameters. If there are
5514 any such packs, it will be instantiated into a fixed template parameter
5515 list by partial instantiation rather than be fully deduced. */
5517 tree
5519 {
5520 /* This can only be true in a member template. */
5523 /* This can only be true for a parameter pack. */
5526 /* A type parm can't refer to another parm. */
5540 }
5542 /* Check that a template declaration's use of default arguments and
5543 parameter packs is not invalid. Here, PARMS are the template
5544 parameters. IS_PRIMARY is true if DECL is the thing declared by
5545 a primary template. IS_PARTIAL is true if DECL is a partial
5546 specialization.
5548 IS_FRIEND_DECL is nonzero if DECL is either a non-defining friend
5549 function template declaration or a friend class template
5550 declaration. In the function case, 1 indicates a declaration, 2
5551 indicates a redeclaration. When IS_FRIEND_DECL=2, no errors are
5552 emitted for extraneous default arguments.
5554 Returns TRUE if there were no errors found, FALSE otherwise. */
5556 bool
5559 {
5562 tree parm_level;
5565 /* [temp.param]
5567 A default template-argument shall not be specified in a
5568 function template declaration or a function template definition, nor
5569 in the template-parameter-list of the definition of a member of a
5570 class template. */
5574 /* You can't have a function template declaration in a local
5575 scope, nor you can you define a member of a class template in a
5576 local scope. */
5584 /* A lambda doesn't have an explicit declaration; don't complain
5585 about the parms of the enclosing class. */
5592 /* If this is either a friend defined in the scope of the class
5593 or a member function. */
5599 /* And, if it was a member function, it really was defined in
5600 the scope of the class. */
5603 /* We already checked these parameters when the template was
5604 declared, so there's no need to do it again now. This function
5605 was defined in class scope, but we're processing its body now
5606 that the class is complete. */
5609 /* Core issue 226 (C++0x only): the following only applies to class
5610 templates. */
5613 {
5614 /* [temp.param]
5616 If a template-parameter has a default template-argument, all
5617 subsequent template-parameters shall have a default
5618 template-argument supplied. */
5620 {
5627 {
5637 {
5639 /* For better subsequent error-recovery, we indicate that
5640 there should have been a default argument. */
5643 }
5645 && !is_friend_decl
5646 /* Don't complain about an enclosing partial
5647 specialization. */
5652 /* A fixed parameter pack will be partially
5653 instantiated into a fixed length list. */
5655 {
5656 /* A primary class template, primary variable template
5657 (DR 2032), or alias template can only have one
5658 parameter pack, at the end of the template
5659 parameter list. */
5667 }
5668 }
5669 }
5670 }
5673 || is_partial
5674 || !is_primary
5676 /* For an ordinary class template, default template arguments are
5677 allowed at the innermost level, e.g.:
5678 template <class T = int>
5679 struct S {};
5680 but, in a partial specialization, they're not allowed even
5681 there, as we have in [temp.class.spec]:
5683 The template parameter list of a specialization shall not
5684 contain default template argument values.
5686 So, for a partial specialization, or for a function template
5687 (in C++98/C++03), we look at all of them. */
5688 ;
5689 else
5690 /* But, for a primary class template that is not a partial
5691 specialization we look at all template parameters except the
5692 innermost ones. */
5695 /* Figure out what error message to issue. */
5710 else
5711 /* Per [temp.param]/9, "A default template-argument shall not be
5712 specified in the template-parameter-lists of the definition of
5713 a member of a class template that appears outside of the member's
5714 class.", thus if we aren't handling a member of a class template
5715 there is no need to examine the parameters. */
5719 /* If we're inside a class definition, there's no need to
5720 examine the parameters to the class itself. On the one
5721 hand, they will be checked when the class is defined, and,
5722 on the other, default arguments are valid in things like:
5723 template <class T = double>
5724 struct S { template <class U> void f(U); };
5725 Here the default argument for `S' has no bearing on the
5726 declaration of `f'. */
5728 else
5729 /* Check everything. */
5735 {
5742 {
5747 {
5749 {
5756 }
5758 /* Clear out the default argument so that we are not
5759 confused later. */
5761 }
5762 }
5764 /* At this point, if we're still interested in issuing messages,
5765 they must apply to classes surrounding the object declared. */
5769 }
5772 }
5774 /* Worker for push_template_decl_real, called via
5775 for_each_template_parm. DATA is really an int, indicating the
5776 level of the parameters we are interested in. If T is a template
5777 parameter of that level, return nonzero. */
5779 static int
5781 {
5787 else
5790 }
5792 /* Worker for uses_outer_template_parms, called via for_each_template_parm.
5793 DATA is really an int, indicating the innermost outer level of parameters.
5794 If T is a template parameter of that level or further out, return
5795 nonzero. */
5797 static int
5799 {
5805 else
5808 }
5810 /* Creates a TEMPLATE_DECL for the indicated DECL using the template
5811 parameters given by current_template_args, or reuses a
5812 previously existing one, if appropriate. Returns the DECL, or an
5813 equivalent one, if it is replaced via a call to duplicate_decls.
5815 If IS_FRIEND is true, DECL is a friend declaration. */
5817 tree
5819 {
5823 /* See if this is a partial specialization. */
5832 /* No surprising friend functions. */
5837 tree ctx;
5839 /* For a friend, we want the context of the friend, not
5840 the type of which it is a friend. */
5844 /* In the case of a virtual function, we want the class in which
5845 it is defined. */
5847 else
5848 /* Otherwise, if we're currently defining some class, the DECL
5849 is assumed to be a member of the class. */
5858 /* See if this is a primary template. */
5862 /* A friend template that specifies a class context, i.e.
5863 template <typename T> friend void A<T>::f();
5864 is not primary. */
5865 ;
5867 /* Lambdas are not primary. */
5868 ;
5869 else
5872 /* True if the template is a member template, in the sense of
5873 [temp.mem]. */
5877 {
5885 {
5888 }
5890 {
5892 {
5895 }
5897 {
5898 /* [temp.mem]
5900 A destructor shall not be a member template. */
5904 }
5911 {
5912 /* [basic.stc.dynamic.allocation]
5914 An allocation function can be a function
5915 template. ... Template allocation functions shall
5916 have two or more parameters. */
5919 }
5920 }
5926 /* alias-declaration */
5932 else
5933 {
5936 }
5937 }
5944 /* Check to see that the rules regarding the use of default
5945 arguments are not being violated. We check args for a friend
5946 functions when we know whether it's a definition, introducing
5947 declaration or re-declaration. */
5952 /* Ensure that there are no parameter packs in the type of this
5953 declaration that have not been expanded. */
5955 {
5956 /* Check each of the arguments individually to see if there are
5957 any bare parameter packs. */
5963 {
5966 {
5967 /* This is a PARM_DECL that contains unexpanded parameter
5968 packs. We have already complained about this in the
5969 check_for_bare_parameter_packs call, so just replace
5970 these types with ERROR_MARK_NODE. */
5973 }
5977 }
5979 /* Check for bare parameter packs in the return type and the
5980 exception specifiers. */
5982 /* Errors were already issued, set return type to int
5983 as the frontend doesn't expect error_mark_node as
5984 the return type. */
5988 }
5989 else
5990 {
5994 {
5997 }
6002 }
6011 {
6012 /* Does not get a template head. */
6015 }
6022 {
6027 /* If DECL is a TYPE_DECL for a class-template, then there won't
6028 be DECL_LANG_SPECIFIC. The information equivalent to
6029 DECL_TEMPLATE_INFO is found in TYPE_TEMPLATE_INFO instead. */
6033 {
6034 /* Since a template declaration already existed for this
6035 class-type, we must be redeclaring it here. Make sure
6036 that the redeclaration is valid. */
6038 current_template_parms,
6040 /* We don't need to create a new TEMPLATE_DECL; just use the
6041 one we already had. */
6043 }
6044 else
6045 {
6047 member_template_p);
6052 {
6053 /* A specialization of a member template of a template
6054 class. */
6058 }
6059 }
6060 }
6061 else
6062 {
6068 {
6071 }
6079 {
6080 /* The declaration is a specialization of a member
6081 template, declared outside the class. Therefore, the
6082 innermost template arguments will be NULL, so we
6083 replace them with the arguments determined by the
6084 earlier call to check_explicit_specialization. */
6087 tree new_tmpl
6089 member_template_p);
6097 args,
6100 }
6102 /* Make sure the template headers we got make sense. */
6107 {
6112 }
6113 else
6115 {
6120 {
6124 else
6128 /* Avoid crash in import_export_decl. */
6131 }
6136 /* Can happen in erroneous input. */
6138 else
6140 }
6142 /* Check that the parms are used in the appropriate qualifying scopes
6143 in the declarator. */
6147 {
6153 /* Avoid crash in import_export_decl. */
6156 }
6158 /* Check that the constraints for each enclosing template scope are
6159 consistent with the original declarations. */
6161 {
6165 {
6168 }
6170 {
6172 {
6176 }
6179 }
6180 }
6181 }
6186 {
6187 /* Push template declarations for global functions and types.
6188 Note that we do not try to push a global template friend
6189 declared in a template class; such a thing may well depend on
6190 the template parameters of the class and we'll push it when
6191 instantiating the befriending class. */
6194 {
6199 /* pushdecl may have found an existing template. */
6201 {
6204 }
6205 }
6207 {
6208 /* Record this decl as belonging to the current class. It's
6209 not chained onto anything else. */
6213 }
6214 }
6216 /* The type may have been completed, or (erroneously) changed. */
6220 {
6222 {
6227 /* Give template template parms a DECL_CONTEXT of the template
6228 for which they are a parameter. */
6231 {
6235 }
6239 {
6242 {
6243 /* ??? Why don't we do this here for all templates? */
6246 }
6247 }
6248 }
6250 /* The DECL_TI_ARGS of DECL contains full set of arguments
6251 referring wback to its most general template. If TMPL is a
6252 specialization, ARGS may only have the innermost set of
6253 arguments. Add the missing argument levels if necessary. */
6261 else
6262 {
6265 }
6266 }
6269 && !is_friend
6272 /* Set DECL_COMDAT on template instantiations; if we force
6273 them to be emitted by explicit instantiation,
6274 mark_needed will tell cgraph to do the right thing. */
6280 }
6282 /* FN is an inheriting constructor that inherits from the constructor
6283 template INHERITED; turn FN into a constructor template with a matching
6284 template header. */
6286 tree
6288 {
6289 tree inner_parms
6292 tree parms
6301 }
6303 /* Called when a class template TYPE is redeclared with the indicated
6304 template PARMS, e.g.:
6306 template <class T> struct S;
6307 template <class T> struct S {}; */
6309 bool
6311 {
6312 tree tmpl;
6313 tree tmpl_parms;
6317 {
6320 }
6324 /* The type is nested in some template class. Nothing to worry
6325 about here; there are no new template parameters for the nested
6326 type. */
6330 {
6332 tmpl);
6334 }
6340 {
6350 }
6353 {
6354 tree tmpl_parm;
6355 tree parm;
6367 /* TMPL_PARM and PARM can be either TYPE_DECL, PARM_DECL, or
6368 TEMPLATE_DECL. */
6378 {
6379 auto_diagnostic_group d;
6383 else
6386 }
6388 /* The parameters can be declared to introduce different
6389 constraints. */
6393 {
6394 auto_diagnostic_group d;
6400 }
6402 /* Give each template template parm in this redeclaration a
6403 DECL_CONTEXT of the template for which they are a parameter. */
6405 {
6409 }
6410 }
6419 /* Two classes with different constraints declare different entities. */
6421 {
6422 auto_diagnostic_group d;
6428 }
6431 }
6433 /* The actual substitution part of instantiate_non_dependent_expr,
6434 to be used when the caller has already checked
6435 !instantiation_dependent_uneval_expression_p (expr)
6436 and cleared processing_template_decl. */
6438 tree
6440 {
6442 }
6444 /* Instantiate the non-dependent expression EXPR. */
6446 tree
6449 {
6454 {
6455 /* The caller should have checked this already. */
6457 processing_template_decl_sentinel s;
6459 }
6461 }
6463 /* Like instantiate_non_dependent_expr, but return NULL_TREE if the
6464 expression is dependent or non-constant. */
6466 tree
6468 {
6472 {
6475 else
6476 {
6477 processing_template_decl_sentinel s;
6479 }
6480 }
6482 }
6484 /* True iff T is a specialization of a variable template. */
6486 bool
6488 {
6493 }
6495 /* Return TRUE iff T is a type alias, a TEMPLATE_DECL for an alias
6496 template declaration, or a TYPE_DECL for an alias declaration. */
6498 bool
6500 {
6508 }
6510 /* If T is a specialization of an alias template, return it; otherwise return
6511 NULL_TREE. If TRANSPARENT_TYPEDEFS is true, look through other aliases. */
6513 tree
6516 {
6520 /* It's an alias template specialization if it's an alias and its
6521 TYPE_NAME is a specialization of a primary template. */
6523 {
6530 transparent_typedefs);
6531 }
6534 }
6536 /* A cache of the result of complex_alias_template_p. */
6540 /* Data structure for complex_alias_template_*. */
6542 struct uses_all_template_parms_data
6543 {
6546 };
6548 /* walk_tree callback for complex_alias_template_p. */
6550 static tree
6552 {
6557 {
6562 {
6566 }
6569 }
6574 /* An alias template with a pack expansion that expands a pack from the
6575 enclosing class needs to be considered complex, to avoid confusion with
6576 the same pack being used as an argument to the alias's own template
6577 parameter (91966). */
6580 {
6589 /* Consider the expanded packs to be used outside the expansion... */
6591 }
6593 /* ...but don't walk into the pattern. Consider PR104008:
6595 template <typename T, typename... Ts>
6596 using IsOneOf = disjunction<is_same<T, Ts>...>;
6598 where IsOneOf seemingly uses all of its template parameters in its
6599 expansion (and does not expand a pack from the enclosing class), so the
6600 alias was not marked as complex. However, if it is used like
6601 "IsOneOf<T>", the empty pack for Ts means that T no longer appears in the
6602 expansion. So only Ts is considered used by the pack expansion. */
6606 }
6608 /* An alias template is complex from a SFINAE perspective if a template-id
6609 using that alias can be ill-formed when the expansion is not, as with
6610 the void_t template.
6612 If this predicate returns true in the ordinary case, the out parameter
6613 SEEN_OUT is set to a TREE_VEC containing boolean_true_node at element I if
6614 the I'th template parameter of the alias template is used in the alias. */
6616 static bool
6618 {
6623 /* A renaming alias isn't complex. */
6627 /* Any other constrained alias is complex. */
6635 {
6645 }
6658 {
6661 }
6665 {
6670 }
6674 }
6676 /* If T is a specialization of a complex alias template with a dependent
6677 argument for an unused template parameter, return it; otherwise return
6678 NULL_TREE. If T is a typedef to such a specialization, return the
6679 specialization. */
6681 tree
6683 {
6692 {
6695 {
6698 {
6701 }
6702 else
6703 {
6709 }
6712 }
6713 }
6716 {
6719 }
6722 }
6724 /* Return the number of innermost template parameters in TMPL. */
6726 static int
6728 {
6731 }
6733 /* Return either TMPL or another template that it is equivalent to under DR
6734 1286: An alias that just changes the name of a template is equivalent to
6735 the other template. */
6737 static tree
6739 {
6742 {
6743 /* Determine if the alias is equivalent to an underlying template. */
6745 /* The underlying type may have been ill-formed. Don't proceed. */
6758 /* Does the alias add cv-quals? */
6766 /* Are any default template arguments equivalent? */
6771 {
6776 }
6778 /* If TMPL adds or changes any constraints, it isn't equivalent. I think
6779 it's appropriate to treat a less-constrained alias as equivalent. */
6783 /* Alias is equivalent. Strip it and repeat. */
6785 }
6786 top_break:;
6789 }
6791 /* Subroutine of convert_nontype_argument. Converts EXPR to TYPE, which
6792 must be a reference-to-function or a pointer-to-function type, as specified
6793 in [temp.arg.nontype]: disambiguate EXPR if it is an overload set,
6794 and check that the resulting function has external linkage. */
6796 static tree
6798 tsubst_flags_t complain)
6799 {
6802 linkage_kind linkage;
6820 /* [temp.arg.nontype]/1
6822 A template-argument for a non-type, non-template template-parameter
6823 shall be one of:
6824 [...]
6825 -- the address of an object or function with external [C++11: or
6826 internal] linkage. */
6830 {
6832 {
6839 else
6842 }
6844 }
6849 {
6851 {
6857 else
6861 }
6863 }
6865 accept:
6867 {
6870 else
6872 }
6877 }
6879 /* Subroutine of convert_nontype_argument.
6880 Check if EXPR of type TYPE is a valid pointer-to-member constant.
6881 Emit an error otherwise. */
6883 static bool
6885 tsubst_flags_t complain)
6886 {
6902 {
6908 else
6910 }
6912 }
6914 /* Returns TRUE iff the address of OP is value-dependent.
6916 14.6.2.4 [temp.dep.temp]:
6917 A non-integral non-type template-argument is dependent if its type is
6918 dependent or it has either of the following forms
6919 qualified-id
6920 & qualified-id
6921 and contains a nested-name-specifier which specifies a class-name that
6922 names a dependent type.
6924 We generalize this to just say that the address of a member of a
6925 dependent class is value-dependent; the above doesn't cover the
6926 address of a static data member named with an unqualified-id. */
6928 static bool
6930 {
6933 /* We could use get_inner_reference here, but there's no need;
6934 this is only relevant for template non-type arguments, which
6935 can only be expressed as &id-expression. */
6937 {
6948 }
6951 }
6953 /* The next set of functions are used for providing helpful explanatory
6954 diagnostics for failed overload resolution. Their messages should be
6955 indented by two spaces for consistency with the messages in
6956 call.cc */
6958 static int
6960 {
6962 }
6964 /* Other failure functions should call this one, to provide a single function
6965 for setting a breakpoint on. */
6967 static int
6969 {
6971 }
6973 static int
6975 {
6980 }
6982 static int
6984 {
6990 }
6992 static int
6994 {
6998 }
7000 static int
7002 {
7005 " template parameter %qD is not a parameter pack, but "
7009 }
7011 static int
7013 {
7016 " template argument %qE does not match "
7020 }
7022 static int
7024 {
7028 }
7030 static int
7032 {
7038 }
7040 static int
7042 {
7044 {
7049 else
7051 " deduced conflicting values for non-type parameter "
7053 }
7055 }
7057 static int
7059 {
7062 " variable-sized array type %qT is not "
7064 arg);
7066 }
7068 static int
7070 {
7074 arg);
7076 }
7078 static int
7080 {
7082 {
7088 else
7093 }
7095 }
7097 static int
7099 {
7101 }
7103 static int
7106 {
7108 }
7110 static int
7113 {
7119 }
7121 static int
7124 {
7127 {
7135 }
7137 }
7139 static int
7141 {
7144 " template parameters of a template template argument are "
7147 }
7149 static int
7151 {
7157 }
7159 static int
7161 {
7166 }
7168 /* Subroutine of convert_nontype_argument, to check whether EXPR, as an
7169 argument for TYPE, points to an unsuitable object.
7171 Also adjust the type of the index in C++20 array subobject references. */
7173 static bool
7175 {
7177 {
7178 CASE_CONVERT:
7180 complain);
7184 complain);
7187 {
7191 }
7195 {
7201 {
7205 /* Canonicalize array offsets to ptrdiff_t; how they were
7206 written doesn't matter for subobject identity. */
7209 }
7212 {
7215 "%qE is not a valid template argument of type %qT "
7219 }
7221 {
7224 "%qE is not a valid template argument of type %qT "
7228 }
7231 {
7234 "%qE is not a valid template argument of type %qT "
7237 }
7238 /* C++17: For a non-type template-parameter of reference or pointer
7239 type, the value of the constant expression shall not refer to (or
7240 for a pointer type, shall not be the address of):
7241 * a subobject (4.5),
7242 * a temporary object (15.2),
7243 * a string literal (5.13.5),
7244 * the result of a typeid expression (8.2.8), or
7245 * a predefined __func__ variable (11.4.1). */
7248 {
7252 decl);
7254 }
7256 && !(same_type_ignoring_top_level_qualifiers_p
7259 {
7264 }
7266 {
7270 decl);
7272 }
7273 }
7281 else
7282 {
7284 {
7287 "because %qD is a variable, not the address of "
7290 }
7291 else
7292 {
7298 }
7299 }
7300 }
7303 }
7305 /* Return a VAR_DECL for the C++20 template parameter object corresponding to
7306 template argument EXPR. */
7308 static tree
7310 {
7316 {
7321 }
7325 /* This is no longer a compound literal. */
7329 }
7331 /* The template arguments corresponding to template parameter objects of types
7332 that contain pointers to members. */
7336 /* Find or build an nttp object for (already-validated) EXPR with name
7337 NAME. */
7339 tree
7341 {
7358 {
7359 /* If EXPR contains any PTRMEM_CST, they will get clobbered by
7360 lower_var_init before we're done mangling. So store the original
7361 value elsewhere. */
7364 }
7369 }
7371 /* Return the actual template argument corresponding to template parameter
7372 object VAR. */
7374 tree
7376 {
7380 }
7382 /* Attempt to convert the non-type template parameter EXPR to the
7383 indicated TYPE. If the conversion is successful, return the
7384 converted value. If the conversion is unsuccessful, return
7385 NULL_TREE if we issued an error message, or error_mark_node if we
7386 did not. We issue error messages for out-and-out bad template
7387 parameters, but not simply because the conversion failed, since we
7388 might be just trying to do argument deduction. Both TYPE and EXPR
7389 must be non-dependent.
7391 The conversion follows the special rules described in
7392 [temp.arg.nontype], and it is much more strict than an implicit
7393 conversion.
7395 This function is called twice for each template argument (see
7396 lookup_template_class for a more accurate description of this
7397 problem). This means that we need to handle expressions which
7398 are not valid in a C++ source, but can be created from the
7399 first call (for instance, casts to perform conversions). These
7400 hacks can go away after we fix the double coercion problem. */
7402 static tree
7404 {
7405 tree expr_type;
7408 /* Detect immediately string literals as invalid non-type argument.
7409 This special-case is not needed for correctness (we would easily
7410 catch this later), but only to provide better diagnostic for this
7411 common user mistake. As suggested by DR 100, we do not mention
7412 linkage issues in the diagnostic as this is not the point. */
7414 {
7420 }
7422 /* Add the ADDR_EXPR now for the benefit of
7423 value_dependent_expression_p. */
7426 {
7430 }
7432 /* If we are in a template, EXPR may be non-dependent, but still
7433 have a syntactic, rather than semantic, form. For example, EXPR
7434 might be a SCOPE_REF, rather than the VAR_DECL to which the
7435 SCOPE_REF refers. Preserving the qualifying scope is necessary
7436 so that access checking can be performed when the template is
7437 instantiated -- but here we need the resolved form so that we can
7438 convert the argument. */
7450 /* If the argument is non-dependent, perform any conversions in
7451 non-dependent context as well. */
7459 else
7462 /* 14.3.2/5: The null pointer{,-to-member} conversion is applied
7463 to a non-type argument of "nullptr". */
7467 /* In C++11, integral or enumeration non-type template arguments can be
7468 arbitrary constant expressions. Pointer and pointer to
7469 member arguments can be general constant expressions that evaluate
7470 to a null value, but otherwise still need to be of a specific form. */
7472 {
7474 /* A PTRMEM_CST is already constant, and a valid template
7475 argument for a parameter of pointer to member type, we just want
7476 to leave it in that form rather than lower it to a
7480 {
7481 /* C++17: A template-argument for a non-type template-parameter shall
7482 be a converted constant expression (8.20) of the type of the
7483 template-parameter. */
7486 /* Make sure we return NULL_TREE only if we have really issued
7487 an error, as described above. */
7490 {
7493 }
7496 /* EXPR may have become value-dependent. */
7498 }
7500 {
7505 }
7506 }
7510 else
7513 /* HACK: Due to double coercion, we can get a
7514 NOP_EXPR<REFERENCE_TYPE>(ADDR_EXPR<POINTER_TYPE> (arg)) here,
7515 which is the tree that we built on the first call (see
7516 below when coercing to reference to object or to reference to
7517 function). We just strip everything and get to the arg.
7518 See g++.old-deja/g++.oliva/template4.C and g++.dg/template/nontype9.C
7519 for examples. */
7521 {
7522 /* Check this before we strip *& to avoid redundancy. */
7531 {
7532 /* ??? Maybe we could use convert_from_reference here, but we
7533 would need to relax its constraints because the NOP_EXPR
7534 could actually change the type to something more cv-qualified,
7535 and this is not folded by convert_from_reference. */
7540 && (same_type_ignoring_top_level_qualifiers_p
7543 {
7546 }
7547 }
7548 }
7550 /* [temp.arg.nontype]/5, bullet 1
7552 For a non-type template-parameter of integral or enumeration type,
7553 integral promotions (_conv.prom_) and integral conversions
7554 (_conv.integral_) are applied. */
7557 {
7559 {
7564 }
7569 /* Notice that there are constant expressions like '4 % 0' which
7570 do not fold into integer constants. */
7572 {
7574 {
7578 else
7584 /* else cxx_constant_value complained but gave us
7585 a real constant, so go ahead. */
7587 {
7588 /* Some assemble time constant expressions like
7589 (intptr_t)&&lab1 - (intptr_t)&&lab2 or
7590 4 + (intptr_t)&&var satisfy reduced_constant_expression_p
7591 as we can emit them into .rodata initializers of
7592 variables, yet they can't fold into an INTEGER_CST at
7593 compile time. Refuse them here. */
7598 }
7599 }
7600 else
7602 }
7604 /* Avoid typedef problems. */
7607 }
7608 /* [temp.arg.nontype]/5, bullet 2
7610 For a non-type template-parameter of type pointer to object,
7611 qualification conversions (_conv.qual_) and the array-to-pointer
7612 conversion (_conv.array_) are applied. */
7614 {
7617 /* Look through any NOP_EXPRs around an ADDR_EXPR, whether they come from
7618 decay_conversion or an explicit cast. If it's a problematic cast,
7619 we'll complain about it below. */
7621 {
7626 {
7629 }
7630 }
7632 /* [temp.arg.nontype]/1 (TC1 version, DR 49):
7634 A template-argument for a non-type, non-template template-parameter
7635 shall be one of: [...]
7637 -- the name of a non-type template-parameter;
7638 -- the address of an object or function with external linkage, [...]
7639 expressed as "& id-expression" where the & is optional if the name
7640 refers to a function or array, or if the corresponding
7641 template-parameter is a reference.
7643 Here, we do not care about functions, as they are invalid anyway
7644 for a parameter of type pointer-to-object. */
7647 /* Non-type template parameters are OK. */
7648 ;
7653 /* Other values, like integer constants, might be valid
7654 non-type arguments of some other type. */
7664 }
7665 /* [temp.arg.nontype]/5, bullet 3
7667 For a non-type template-parameter of type reference to object, no
7668 conversions apply. The type referred to by the reference may be more
7669 cv-qualified than the (otherwise identical) type of the
7670 template-argument. The template-parameter is bound directly to the
7671 template-argument, which must be an lvalue. */
7673 {
7675 expr_type))
7679 {
7684 }
7687 {
7692 }
7694 /* [temp.arg.nontype]/1
7696 A template-argument for a non-type, non-template template-parameter
7697 shall be one of: [...]
7699 -- the address of an object or function with external linkage. */
7702 {
7705 {
7708 "because a reference variable does not have a constant "
7711 }
7712 }
7715 /* OK, dependent reference. We don't want to ask whether a DECL is
7717 else
7718 {
7723 }
7727 }
7728 /* [temp.arg.nontype]/5, bullet 4
7730 For a non-type template-parameter of type pointer to function, only
7731 the function-to-pointer conversion (_conv.func_) is applied. If the
7732 template-argument represents a set of overloaded functions (or a
7733 pointer to such), the matching function is selected from the set
7734 (_over.over_). */
7736 {
7737 /* If the argument is a template-id, we might not have enough
7738 context information to decay the pointer. */
7740 {
7744 }
7747 /* Null pointer values are OK in C++11. */
7753 }
7754 /* [temp.arg.nontype]/5, bullet 5
7756 For a non-type template-parameter of type reference to function, no
7757 conversions apply. If the template-argument represents a set of
7758 overloaded functions, the matching function is selected from the set
7759 (_over.over_). */
7761 {
7763 {
7765 {
7770 }
7772 }
7777 }
7778 /* [temp.arg.nontype]/5, bullet 6
7780 For a non-type template-parameter of type pointer to member function,
7781 no conversions apply. If the template-argument represents a set of
7782 overloaded member functions, the matching member function is selected
7783 from the set (_over.over_). */
7785 {
7790 /* [temp.arg.nontype] bullet 1 says the pointer to member
7791 expression must be a pointer-to-member constant. */
7796 /* Repeated conversion can't deal with a conversion that turns PTRMEM_CST
7797 into a CONSTRUCTOR, so build up a new PTRMEM_CST instead. */
7800 }
7801 /* [temp.arg.nontype]/5, bullet 7
7803 For a non-type template-parameter of type pointer to data member,
7804 qualification conversions (_conv.qual_) are applied. */
7806 {
7807 /* [temp.arg.nontype] bullet 1 says the pointer to member
7808 expression must be a pointer-to-member constant. */
7816 }
7818 {
7820 {
7825 }
7827 }
7829 {
7830 /* Replace the argument with a reference to the corresponding template
7831 parameter object. */
7836 }
7837 /* A template non-type parameter must be one of the above. */
7838 else
7841 /* Sanity check: did we actually convert the argument to the
7842 right type? */
7846 }
7848 /* Subroutine of coerce_template_template_parms, which returns 1 if
7849 PARM_PARM and ARG_PARM match using the rule for the template
7850 parameters of template template parameters. Both PARM and ARG are
7851 template parameters; the rest of the arguments are the same as for
7852 coerce_template_template_parms.
7853 */
7854 static int
7856 tree arg,
7857 tsubst_flags_t complain,
7858 tree in_decl,
7859 tree outer_args)
7860 {
7869 {
7871 /* We encounter instantiations of templates like
7872 template <template <template <class> class> class TT>
7873 class C; */
7874 {
7878 }
7879 /* Fall through. */
7884 /* Argument is a parameter pack but parameter is not. */
7889 /* The tsubst call is used to handle cases such as
7891 template <int> class C {};
7892 template <class T, template <T> class TT> class D {};
7893 D<int, C> d;
7895 i.e. the parameter list of TT depends on earlier parameters. */
7897 {
7902 }
7906 /* Argument is a parameter pack but parameter is not. */
7913 }
7916 }
7918 /* Coerce template argument list ARGLIST for use with template
7919 template-parameter TEMPL. */
7921 static tree
7923 tsubst_flags_t complain)
7924 {
7925 /* Consider an example where a template template parameter declared as
7927 template <class T, class U = std::allocator<T> > class TT
7929 The template parameter level of T and U are one level larger than
7930 of TT. To proper process the default argument of U, say when an
7931 instantiation `TT<int>' is seen, we need to build the full
7932 arguments containing {int} as the innermost level. Outer levels,
7933 available when not appearing as default template argument, can be
7934 obtained from the arguments of the enclosing template.
7936 Suppose that TT is later substituted with std::vector. The above
7937 instantiation is `TT<int, std::allocator<T> >' with TT at
7938 level 1, and T at level 2, while the template arguments at level 1
7939 becomes {std::vector} and the inner level 2 is {int}. */
7945 {
7946 /* This is an argument of the current template, so we haven't set
7947 DECL_CONTEXT yet. We can also get here when level-lowering a
7948 bound ttp. */
7949 tree relevant_template_parms;
7951 /* Parameter levels that are greater than the level of the given
7952 template template parm are irrelevant. */
7959 }
7966 }
7968 /* A cache of template template parameters with match-all default
7969 arguments. */
7972 /* T is a bound template template-parameter. Copy its arguments into default
7973 arguments of the template template-parameter's template parameters. */
7975 static tree
7977 {
8000 {
8003 {
8006 }
8007 }
8011 tree gen_ntmpl;
8014 else
8024 }
8026 /* ARG is a bound potential template template-argument, and PARGS is a list
8027 of arguments for the corresponding template template-parameter. Adjust
8028 PARGS as appropriate for application to ARG's template, and if ARG is a
8029 BOUND_TEMPLATE_TEMPLATE_PARM, possibly adjust it to add default template
8030 arguments to the template template parameter. */
8032 static tree
8034 {
8038 {
8039 /* When comparing two template template-parameters in partial ordering,
8040 rewrite the one currently being used as an argument to have default
8041 arguments for all parameters. */
8047 }
8048 else
8049 {
8050 tree aparms
8053 }
8056 }
8058 /* Subroutine of unify for the case when PARM is a
8059 BOUND_TEMPLATE_TEMPLATE_PARM. */
8061 static int
8064 {
8068 /* The template template parm might be variadic and the argument
8069 not, so flatten both argument lists. */
8074 {
8075 /* In keeping with P0522R0, adjust P's template arguments
8076 to apply to A's template; then flatten it again. */
8084 /* If the P0522 adjustment eliminated a pack expansion, deduce
8085 empty packs. */
8091 }
8092 else
8093 {
8094 /* Deduce arguments T, i from TT<T> or TT<i>.
8095 We check each element of PARMVEC and ARGVEC individually
8096 rather than the whole TREE_VEC since they can have
8097 different number of elements, which is allowed under N2555. */
8101 /* Check if the parameters end in a pack, making them
8102 variadic. */
8109 /* If the template argument list of P contains a pack
8110 expansion that is not the last template argument, the
8111 entire template argument list is a non-deduced
8112 context. */
8130 DEDUCE_EXACT,
8133 }
8136 }
8138 /* Return 1 if PARM_TMPL and ARG_TMPL match using rule for
8139 template template parameters.
8141 Consider the example:
8142 template <class T> class A;
8143 template<template <class U> class TT> class B;
8145 For B<A>, PARM_TMPL is TT, while ARG_TMPL is A,
8146 and OUTER_ARGS contains A. */
8148 static int
8150 tree arg_tmpl,
8151 tsubst_flags_t complain,
8152 tree in_decl,
8153 tree outer_args)
8154 {
8168 {
8169 /* P0522R0: A template template-parameter P is at least as specialized as
8170 a template template-argument A if, given the following rewrite to two
8171 function templates, the function template corresponding to P is at
8172 least as specialized as the function template corresponding to A
8173 according to the partial ordering rules for function templates
8174 ([temp.func.order]). Given an invented class template X with the
8175 template parameter list of A (including default arguments):
8177 * Each of the two function templates has the same template parameters,
8178 respectively, as P or A.
8180 * Each function template has a single function parameter whose type is
8181 a specialization of X with template arguments corresponding to the
8182 template parameters from the respective function template where, for
8183 each template parameter PP in the template parameter list of the
8184 function template, a corresponding template argument AA is formed. If
8185 PP declares a parameter pack, then AA is the pack expansion
8186 PP... ([temp.variadic]); otherwise, AA is the id-expression PP.
8188 If the rewrite produces an invalid type, then P is not at least as
8189 specialized as A. */
8191 /* So coerce P's args to apply to A's parms, and then deduce between A's
8192 args and the converted args. If that succeeds, A is at least as
8193 specialized as P, so they match.*/
8199 /* PARM and ARG might be at different template depths, and we want to
8200 pass the right additional levels of args when coercing PARGS to
8201 ARG_PARMS in case we need to do any substitution into non-type
8202 template parameter types.
8204 OUTER_ARGS are not the right outer levels in this case, as they are
8205 the args we're building up for PARM, and for the coercion we want the
8206 args for ARG. If DECL_CONTEXT isn't set for a template template
8207 parameter, we can assume that it's in the current scope. */
8215 {
8220 /* Only use as many levels from the scope as needed
8221 (excluding the level of ARG). */
8225 else
8228 /* Add the arguments that appear at the levels of ARG. */
8235 }
8236 else
8242 {
8248 }
8249 }
8251 /* Determine whether we have a parameter pack at the end of the
8252 template template parameter's template parameter list. */
8254 {
8261 {
8275 }
8276 }
8282 /* Check all of the template parameters except the parameter pack at
8283 the end (if any). */
8285 {
8294 outer_args))
8297 }
8300 {
8301 /* Check each of the template parameters in the template
8302 argument against the template parameter pack at the end of
8303 the template template parameter. */
8310 {
8317 outer_args))
8319 }
8320 }
8323 }
8325 /* Verifies that the deduced template arguments (in TARGS) for the
8326 template template parameters (in TPARMS) represent valid bindings,
8327 by comparing the template parameter list of each template argument
8328 to the template parameter list of its corresponding template
8329 template parameter, in accordance with DR150. This
8330 routine can only be called after all template arguments have been
8331 deduced. It will return TRUE if all of the template template
8332 parameter bindings are okay, FALSE otherwise. */
8333 bool
8335 {
8339 /* We're dealing with template parms in this process. */
8345 {
8350 {
8355 {
8356 /* Look inside the argument pack. */
8359 }
8362 {
8364 /* Extract the next argument from the argument
8365 pack. */
8369 /* Look at the pattern of the pack expansion. */
8372 /* Extract the template parameters from the template
8373 argument. */
8377 /* Verify that we can coerce the template template
8378 parameters from the template argument to the template
8379 parameter. This requires an exact match. */
8381 && !coerce_template_template_parms
8383 targ,
8384 tf_none,
8385 tparm,
8386 targs))
8387 {
8390 }
8391 }
8392 }
8393 }
8395 out:
8399 }
8401 /* Since type attributes aren't mangled, we need to strip them from
8402 template type arguments. */
8404 tree
8406 {
8416 }
8418 /* And from inside dependent non-type arguments like sizeof(Type). */
8420 static tree
8422 {
8432 }
8434 /* A template declaration can be substituted for a constrained
8435 template template parameter only when the argument is no more
8436 constrained than the parameter. */
8438 static bool
8440 {
8443 /* For now, allow constrained template template arguments
8444 and unconstrained template template parameters. */
8448 /* If the template parameter is constrained, we need to rewrite its
8449 constraints in terms of the ARG's template parameters. This ensures
8450 that all of the template parameter types will have the same depth.
8452 Note that this is only valid when coerce_template_template_parm is
8453 true for the innermost template parameters of PARM and ARG. In other
8454 words, because coercion is successful, this conversion will be valid. */
8457 {
8467 }
8470 }
8472 // Convert a placeholder argument into a binding to the original
8473 // parameter. The original parameter is saved as the TREE_TYPE of
8474 // ARG.
8477 {
8480 }
8482 /* We can't fully resolve ARG given as a non-type template argument to TYPE,
8483 because one of them is dependent. But we need to represent the
8484 conversion for the benefit of cp_tree_equal. */
8486 static tree
8488 {
8489 /* Auto parms get no conversion. */
8492 /* ??? Do we need to push the IMPLICIT_CONV_EXPR into the pack expansion?
8493 That would complicate other things, and it doesn't seem necessary. */
8496 /* We don't need or want to add this conversion now if we're going to use the
8497 argument for deduction. */
8512 }
8514 /* Convert the indicated template ARG as necessary to match the
8515 indicated template PARM. Returns the converted ARG, or
8516 error_mark_node if the conversion was unsuccessful. Error and
8517 warning messages are issued under control of COMPLAIN. This
8518 conversion is for the Ith parameter in the parameter list. ARGS is
8519 the full set of template arguments deduced so far. */
8521 static tree
8523 tree arg,
8524 tree args,
8525 tsubst_flags_t complain,
8527 tree in_decl)
8528 {
8529 tree orig_arg;
8530 tree val;
8536 /* Trivially convert placeholders. */
8545 {
8546 /* The template argument was the name of some
8547 member function. That's usually
8548 invalid, but static members are OK. In any
8549 case, grab the underlying fields/functions
8550 and issue an error later if required. */
8552 }
8560 /* When determining whether an argument pack expansion is a template,
8561 look at the pattern. */
8565 /* Deal with an injected-class-name used as a template template arg. */
8567 {
8570 {
8580 }
8581 }
8583 is_tmpl_type =
8599 {
8601 {
8605 }
8608 "to refer to a type member of a template parameter, "
8613 typename_type,
8614 complain);
8617 }
8619 {
8621 {
8623 {
8628 {
8629 /* The template argument is a type, but we're expecting
8630 an expression. */
8635 /* [temp.arg]/2: "In a template-argument, an ambiguity
8636 between a type-id and an expression is resolved to a
8637 type-id, regardless of the form of the corresponding
8638 template-parameter." So give the user a clue. */
8641 "for non-type template parameter is treated as "
8643 }
8647 else
8650 }
8651 }
8653 }
8655 {
8657 {
8664 else
8667 }
8669 }
8672 /* We already did the appropriate conversion when packing args. */
8675 {
8677 {
8679 /* The number of argument required is not known yet.
8680 Just accept it for now. */
8682 else
8683 {
8684 /* Strip alias templates that are equivalent to another
8685 template. */
8690 args))
8691 {
8694 /* TEMPLATE_TEMPLATE_PARM node is preferred over
8695 TEMPLATE_DECL. */
8697 {
8702 }
8703 }
8704 else
8705 {
8707 {
8714 }
8717 }
8719 // Check that the constraints are compatible before allowing the
8720 // substitution.
8723 {
8725 {
8731 }
8733 }
8734 }
8735 }
8736 else
8738 /* We only form one instance of each template specialization.
8739 Therefore, if we use a non-canonical variant (i.e., a
8740 typedef), any future messages referring to the type will use
8741 the typedef, which is confusing if those future uses do not
8742 themselves also use the typedef. */
8745 }
8746 else
8747 {
8752 /* We don't have enough levels of args to do any substitution. This
8755 {
8760 }
8761 else
8764 /* Perform array-to-pointer and function-to-pointer conversion
8765 as per [temp.param]/10. */
8771 /* Drop top-level cv-qualifiers on the substituted/deduced type of
8772 this non-type template parameter, as per [temp.param]/6. */
8778 /* We need to handle arguments for alias or concept templates
8779 differently: we need to force building an IMPLICIT_CONV_EXPR, because
8780 these arguments are going to be substituted directly into the
8781 dependent type; they might not get another chance at
8782 convert_nontype_argument. But if the argument ends up here again for
8783 a template that isn't one of those, remove the conversion for
8784 consistency between naming the same dependent type directly or through
8785 an alias. */
8796 /* We used to call digest_init here. However, digest_init
8797 will report errors, which we don't want when complain
8798 is zero. More importantly, digest_init will try too
8799 hard to convert things: for example, `0' should not be
8800 converted to pointer type at this point according to
8801 the standard. Accepting this is not merely an
8802 extension, since deciding whether or not these
8803 conversions can occur is part of determining which
8804 function template to call, or whether a given explicit
8805 argument specification is valid. */
8807 else
8808 {
8811 }
8821 {
8822 /* Reject template arguments that are references to built-in
8823 functions with no library fallbacks. */
8832 }
8835 {
8836 /* Strip typedefs from the SCOPE_REF. */
8839 complain);
8842 }
8843 }
8846 }
8848 /* Coerces the remaining template arguments in INNER_ARGS (from
8849 ARG_IDX to the end) into the parameter pack at PARM_IDX in PARMS.
8850 Returns the coerced argument pack. PARM_IDX is the position of this
8851 parameter in the template parameter list. ARGS is the original
8852 template argument list. */
8853 static tree
8856 tree args,
8857 tree inner_args,
8859 tree new_args,
8861 tree in_decl,
8862 tsubst_flags_t complain)
8863 {
8866 tree packed_args;
8867 tree argument_pack;
8874 {
8875 /* When the template parameter is a non-type template parameter pack
8876 or template template parameter pack whose type or template
8877 parameters use parameter packs, we know exactly how many arguments
8878 we are looking for. Build a vector of the instantiated decls for
8879 these template parameters in PACKED_PARMS. */
8880 /* We can't use make_pack_expansion here because it would interpret a
8881 _DECL as a use rather than a declaration. */
8895 /* If we're doing a partial instantiation of a member template,
8896 verify that all of the types used for the non-type
8897 template parameter pack are, in fact, valid for non-type
8898 template parameters. */
8901 {
8904 {
8909 }
8910 /* We don't know how many args we have yet, just
8911 use the unconverted ones for now. */
8913 }
8916 }
8917 /* Check if we have a placeholder pack, which indicates we're
8918 in the context of a introduction list. In that case we want
8919 to match this pack to the single placeholder. */
8923 {
8926 }
8927 else
8930 /* Convert the remaining arguments, which will be a part of the
8931 parameter pack "parm". */
8934 {
8940 {
8941 /* Once we've packed as many args as we have types, stop. */
8945 /* We don't know how many args we have yet, just
8946 use the unconverted ones for now. */
8948 else
8950 }
8953 {
8956 }
8957 else
8960 in_decl);
8964 }
8968 {
8973 }
8978 else
8979 {
8982 }
8989 }
8991 /* Returns the number of pack expansions in the template argument vector
8992 ARGS. */
8994 static int
8996 {
9001 {
9005 }
9007 }
9009 /* Convert all template arguments to their appropriate types, and
9010 return a vector containing the innermost resulting template
9011 arguments. If any error occurs, return error_mark_node. Error and
9012 warning messages are issued under control of COMPLAIN.
9014 If PARMS represents all template parameters levels, this function
9015 returns a vector of vectors representing all the resulting argument
9016 levels. Note that in this case, only the innermost arguments are
9017 coerced because the outermost ones are supposed to have been coerced
9018 already. Otherwise, if PARMS represents only (the innermost) vector
9019 of parameters, this function returns a vector containing just the
9020 innermost resulting arguments.
9022 If REQUIRE_ALL_ARGS is false, argument deduction will be performed
9023 for arguments not specified in ARGS. If REQUIRE_ALL_ARGS is true,
9024 arguments not specified in ARGS must have default arguments which
9025 we'll use to fill in ARGS. */
9027 tree
9029 tree args,
9030 tree in_decl,
9031 tsubst_flags_t complain,
9033 {
9035 tree orig_inner_args;
9036 tree inner_args;
9038 /* When used as a boolean value, indicates whether this is a
9039 variadic template parameter list. Since it's an int, we can also
9040 subtract it from nparms to get the number of non-variadic
9041 parameters. */
9046 /* Adjustment to nparms for fixed parameter packs. */
9051 /* Likewise for parameters with default arguments. */
9059 {
9061 {
9064 }
9066 }
9070 /* Determine if there are any parameter packs or default arguments. */
9072 {
9080 }
9083 /* If there are no parameters that follow a parameter pack, we need to
9084 expand any argument packs so that we can deduce a parameter pack from
9085 some non-packed args followed by an argument pack, as in variadic85.C.
9086 If there are such parameters, we need to leave argument packs intact
9087 so the arguments are assigned properly. This can happen when dealing
9088 with a nested class inside a partial specialization of a class
9089 template, as in variadic92.C, or when deducing a template parameter pack
9090 from a sub-declarator, as in variadic114.C. */
9094 /* Count any pack expansion args. */
9100 && require_all_args
9101 && !variadic_args_p
9104 {
9105 bad_nargs:
9107 {
9109 {
9113 }
9114 else
9121 }
9124 }
9125 /* We can't pass a pack expansion to a non-pack parameter of an alias
9126 template (DR 1430). */
9130 && variadic_args_p
9132 {
9134 {
9136 {
9142 {
9145 "pack expansion argument for non-pack parameter "
9147 else
9149 "pack expansion argument for non-pack parameter "
9153 }
9154 }
9156 found:;
9157 }
9159 }
9161 /* We need to evaluate the template arguments, even though this
9162 template-id may be nested within a "sizeof". */
9163 cp_evaluated ev;
9169 {
9170 tree arg;
9171 tree parm;
9173 /* Get the Ith template parameter. */
9177 {
9180 }
9182 /* Calculate the next argument. */
9185 else
9191 {
9192 /* Some arguments will be placed in the
9193 template parameter pack PARM. */
9200 {
9201 /* We don't know how many args we have yet, just use the
9202 unconverted (and still packed) ones for now. */
9206 }
9210 /* Store this argument. */
9212 {
9213 lost++;
9214 /* We are done with all of the arguments. */
9217 }
9218 else
9219 {
9223 {
9226 }
9227 }
9230 }
9232 {
9234 {
9235 /* "If every valid specialization of a variadic template
9236 requires an empty template parameter pack, the template is
9237 ill-formed, no diagnostic required." So check that the
9238 pattern works with this parameter. */
9243 in_decl);
9245 {
9250 }
9252 /* Recover from missing typename. */
9256 /* We don't know how many args we have yet, just
9257 use the unconverted ones for now. */
9261 }
9262 }
9264 {
9265 /* There must be a default arg in this case. */
9268 /* The position of the first default template argument,
9269 is also the number of non-defaulted arguments in NEW_INNER_ARGS.
9270 Record that. */
9274 }
9275 else
9279 {
9282 }
9284 {
9285 /* This can occur if there was an error in the template
9286 parameter list itself (which we would already have
9287 reported) that we are trying to recover from, e.g., a class
9288 template with a parameter list such as
9289 template<typename..., typename> (cpp0x/variadic150.C). */
9292 /* This can also happen with a fixed parameter pack (71834). */
9295 }
9296 else
9302 lost++;
9305 }
9308 {
9309 /* If we had fixed parameter packs, we didn't know how many arguments we
9310 actually needed earlier; now we do. */
9314 }
9317 {
9318 /* We had some pack expansion arguments that will only work if the packs
9319 are empty, but wait until instantiation time to complain.
9320 See variadic-ttp3.C. */
9322 /* Except that we can't provide empty packs to alias templates or
9323 concepts when there are no corresponding parameters. Basically,
9324 we can get here with this:
9326 template<typename T> concept C = true;
9328 template<typename... Args>
9329 requires C<Args...>
9330 void f();
9332 When parsing C<Args...>, we try to form a concept check of
9333 C<?, Args...>. Without the extra check for substituting an empty
9334 pack past the last parameter, we can accept the check as valid.
9336 FIXME: This may be valid for alias templates (but I doubt it).
9338 FIXME: The error could be better also. */
9340 {
9345 }
9356 }
9359 {
9362 }
9369 }
9371 /* Returns true if T is a wrapper to make a C++20 template parameter
9372 object const. */
9374 static bool
9376 {
9382 }
9384 /* Returns 1 if template args OT and NT are equivalent. */
9386 int
9388 {
9401 /* DR 1558: Don't treat an alias template specialization with dependent
9402 arguments as equivalent to its underlying type when used as a template
9403 argument; we need them to be distinct so that we substitute into the
9404 specialization arguments at instantiation time. And aliases can't be
9405 equivalent without being ==, so we don't need to look any deeper.
9407 During partial ordering, however, we need to treat them normally so we can
9408 order uses of the same alias with different cv-qualification (79960). */
9414 /* For member templates */
9427 {
9431 }
9432 else
9433 {
9434 /* Try to treat a template non-type argument that has been converted
9435 to the parameter type as equivalent to one that hasn't yet. */
9449 }
9450 }
9452 /* Returns true iff the OLDARGS and NEWARGS are in fact identical sets of
9453 template arguments. Returns false otherwise, and updates OLDARG_PTR and
9454 NEWARG_PTR with the offending arguments if they are non-NULL. */
9456 bool
9459 {
9470 {
9475 {
9481 }
9482 }
9484 }
9486 static bool
9488 {
9493 }
9495 /* Implement a freelist interface for objects of type T.
9497 Head is a separate object, rather than a regular member, so that we
9498 can define it as a GTY deletable pointer, which is highly
9499 desirable. A data member could be declared that way, but then the
9500 containing object would implicitly get GTY((user)), which would
9501 prevent us from instantiating freelists as global objects.
9502 Although this way we can create freelist global objects, they're
9503 such thin wrappers that instantiating temporaries at every use
9504 loses nothing and saves permanent storage for the freelist object.
9506 Member functions next, anew, poison and reinit have default
9507 implementations that work for most of the types we're interested
9508 in, but if they don't work for some type, they should be explicitly
9509 specialized. See the comments before them for requirements, and
9510 the example specializations for the tree_list_freelist. */
9512 class freelist
9513 {
9514 /* Return the next object in a chain. We could just do type
9515 punning, but if we access the object with its underlying type, we
9516 avoid strict-aliasing trouble. This needs only work between
9517 poison and reinit. */
9520 /* Return a newly allocated, uninitialized or minimally-initialized
9521 object of type T. Any initialization performed by anew should
9522 either remain across the life of the object and the execution of
9523 poison, or be redone by reinit. */
9526 /* Optionally scribble all over the bits holding the object, so that
9527 they become (mostly?) uninitialized memory. This is called while
9528 preparing to make the object part of the free list. */
9533 #ifdef ENABLE_GC_CHECKING
9534 /* Poison the data, to indicate the data is garbage. */
9537 #endif
9538 /* Let valgrind know the object is free. */
9541 /* Let valgrind know the next portion of the object is available,
9542 but uninitialized. */
9544 }
9546 /* Bring an object that underwent at least one lifecycle after anew
9547 and before the most recent free and poison, back to a usable
9548 state, reinitializing whatever is needed for it to be
9549 functionally equivalent to an object just allocated and returned
9550 by anew. This may poison or clear the next field, used by
9551 freelist housekeeping after poison was called. */
9555 #ifdef ENABLE_GC_CHECKING
9557 #endif
9558 /* Let valgrind know the entire object is available, but
9559 uninitialized. */
9561 }
9563 /* Reference a GTY-deletable pointer that points to the first object
9564 in the free list proper. */
9567 /* Construct a freelist object chaining objects off of HEAD. */
9570 /* Add OBJ to the free object list. The former head becomes OBJ's
9571 successor. */
9573 {
9577 }
9579 /* Take an object from the free list, if one is available, or
9580 allocate a new one. Objects taken from the free list should be
9581 regarded as filled with garbage, except for bits that are
9582 configured to be preserved across free and alloc. */
9584 {
9586 {
9591 }
9592 else
9594 }
9595 };
9597 /* Explicitly specialize the interfaces for freelist<tree_node>: we
9598 want to allocate a TREE_LIST using the usual interface, and ensure
9599 TREE_CHAIN remains functional. Alas, we have to duplicate a bit of
9600 build_tree_list logic in reinit, so this could go out of sync. */
9604 {
9606 }
9608 inline tree
9610 {
9612 }
9616 {
9622 #ifdef ENABLE_GC_CHECKING
9625 /* Poison the data, to indicate the data is garbage. */
9628 #endif
9629 /* Let valgrind know the object is free. */
9631 /* But we still want to use the TREE_CODE and TREE_CHAIN parts. */
9635 #ifdef ENABLE_GC_CHECKING
9637 /* Keep TREE_CHAIN functional. */
9639 #else
9641 #endif
9642 }
9646 {
9649 #ifdef ENABLE_GC_CHECKING
9653 #endif
9655 /* Let valgrind know the entire object is available, but
9656 uninitialized. */
9659 #ifdef ENABLE_GC_CHECKING
9661 #else
9664 #endif
9666 }
9668 /* Point to the first object in the TREE_LIST freelist. */
9670 /* Return the/an actual TREE_LIST freelist. */
9673 {
9675 }
9677 /* Point to the first object in the tinst_level freelist. */
9679 /* Return the/an actual tinst_level freelist. */
9682 {
9684 }
9686 /* Point to the first object in the pending_template freelist. */
9688 /* Return the/an actual pending_template freelist. */
9691 {
9693 }
9695 /* Build the TREE_LIST object out of a split list, store it
9696 permanently, and return it. */
9697 tree
9699 {
9708 }
9712 /* Increment OBJ's refcount unless it is already infinite. */
9715 {
9719 }
9721 /* Release storage for OBJ and node, if it's a TREE_LIST. */
9722 void
9724 {
9728 }
9730 /* Decrement OBJ's refcount if not infinite. If it reaches zero, release
9731 OBJ's DECL and OBJ, and start over with the tinst_level object that
9732 used to be referenced by OBJ's NEXT. */
9733 static void
9735 {
9739 {
9743 }
9744 }
9746 /* Modify PTR so that it points to OBJ, adjusting the refcounts of OBJ
9747 and of the former PTR. Omitting the second argument is equivalent
9748 to passing (T*)NULL; this is allowed because passing the
9749 zero-valued integral constant NULL confuses type deduction and/or
9750 overload resolution. */
9752 static void
9754 {
9758 }
9760 static void
9762 {
9772 /* We are called both from instantiate_decl, where we've already had a
9773 tinst_level pushed, and instantiate_template, where we haven't.
9774 Compensate. */
9776 level = !current_tinst_level
9788 else
9797 }
9800 /* Return a TEMPLATE_ID_EXPR corresponding to the indicated FNS and
9801 ARGLIST. Valid choices for FNS are given in the cp-tree.def
9802 documentation for TEMPLATE_ID_EXPR. */
9804 tree
9806 {
9813 {
9816 }
9819 {
9822 unknown_type_node,
9824 arglist);
9826 }
9829 }
9831 /* Within the scope of a template class S<T>, the name S gets bound
9832 (in build_self_reference) to a TYPE_DECL for the class, not a
9833 TEMPLATE_DECL. If DECL is a TYPE_DECL for current_class_type,
9834 or one of its enclosing classes, and that type is a template,
9835 return the associated TEMPLATE_DECL. Otherwise, the original
9836 DECL is returned.
9838 Also handle the case when DECL is a TREE_LIST of ambiguous
9839 injected-class-names from different bases. */
9841 tree
9843 {
9847 /* DR 176: A lookup that finds an injected-class-name (10.2
9848 [class.member.lookup]) can result in an ambiguity in certain cases
9849 (for example, if it is found in more than one base class). If all of
9850 the injected-class-names that are found refer to specializations of
9851 the same class template, and if the name is followed by a
9852 template-argument-list, the reference refers to the class template
9853 itself and not a specialization thereof, and is not ambiguous. */
9855 {
9858 {
9864 }
9867 else
9869 }
9875 }
9877 /* Given an IDENTIFIER_NODE (or type TEMPLATE_DECL) and a chain of
9878 parameters, find the desired type.
9880 D1 is the PTYPENAME terminal, and ARGLIST is the list of arguments.
9882 IN_DECL, if non-NULL, is the template declaration we are trying to
9883 instantiate.
9885 If ENTERING_SCOPE is nonzero, we are about to enter the scope of
9886 the class we are looking up.
9888 Issue error and warning messages under control of COMPLAIN.
9890 If the template class is really a local class in a template
9891 function, then the FUNCTION_CONTEXT is the function in which it is
9892 being instantiated.
9894 ??? Note that this function is currently called *twice* for each
9895 template-id: the first time from the parser, while creating the
9896 incomplete type (finish_template_type), and the second type during the
9897 real instantiation (instantiate_template_class). This is surely something
9898 that we want to avoid. It also causes some problems with argument
9899 coercion (see convert_nontype_argument for more information on this). */
9901 tree
9904 {
9908 tree t;
9911 spec_entry elt;
9912 hashval_t hash;
9915 {
9919 else
9920 {
9927 }
9928 }
9930 {
9933 /* If we are declaring a constructor, say A<T>::A<T>, we will get
9934 an implicit typename for the second A. Deal with it. */
9939 {
9942 }
9943 }
9946 {
9949 }
9951 {
9954 }
9956 {
9959 }
9961 /* Issue an error message if we didn't find a template. */
9963 {
9967 }
9970 /* Make sure it's a user visible template, if it was named by
9971 the user. */
9974 {
9976 {
9980 }
9982 }
9986 /* An alias that just changes the name of a template is equivalent to the
9987 other template, so if any of the arguments are pack expansions, strip
9988 the alias to avoid problems with a pack expansion passed to a non-pack
9989 alias template parameter (DR 1430). */
9994 {
9995 tree parm;
10004 }
10005 else
10006 {
10008 tree gen_tmpl;
10009 tree type_decl;
10017 /* An error occurred while building the template TEMPL, and a
10018 diagnostic has most certainly been emitted for that
10019 already. Let's propagate that error. */
10031 {
10032 /* We've been given an incomplete set of template arguments.
10033 For example, given:
10035 template <class T> struct S1 {
10036 template <class U> struct S2 {};
10037 template <class U> struct S2<U*> {};
10038 };
10040 we will be called with an ARGLIST of `U*', but the
10041 TEMPLATE will be `template <class T> template
10042 <class U> struct S1<T>::S2'. We must fill in the missing
10043 arguments. */
10047 }
10049 /* Now we should have enough arguments. */
10052 /* From here on, we're only interested in the most general
10053 template. */
10055 /* Shortcut looking up the current class scope again. */
10059 {
10070 }
10072 /* Calculate the BOUND_ARGS. These will be the args that are
10073 actually tsubst'd into the definition to create the
10074 instantiation. */
10079 /* We were unable to bind the arguments. */
10082 /* In the scope of a template class, explicit references to the
10083 template class refer to the type of the template, not any
10084 instantiation of it. For example, in:
10086 template <class T> class C { void f(C<T>); }
10088 the `C<T>' is just the same as `C'. Outside of the
10089 class, however, such a reference is an instantiation. */
10093 {
10098 }
10100 /* If we already have this specialization, return it. */
10110 /* If the template's constraints are not satisfied,
10111 then we cannot form a valid type.
10113 Note that the check is deferred until after the hash
10114 lookup. This prevents redundant checks on previously
10115 instantiated specializations. */
10119 {
10121 {
10122 auto_diagnostic_group d;
10125 }
10127 }
10131 /* If the deduced arguments are invalid, then the binding
10132 failed. */
10136 complain))
10143 /* This occurs when the user has tried to define a tagged type
10144 in a scope that forbids it. We emitted an error during the
10145 parse. We didn't complete the bail out then, so here we
10146 are. */
10151 {
10153 /* If the context of the partially instantiated template is
10154 already non-dependent, then we might as well use it. */
10156 else
10157 {
10160 /* Try completing the enclosing context if it's not already so. */
10163 {
10166 {
10167 /* Completion could have caused us to register the desired
10168 specialization already, so check the table again. */
10172 }
10173 }
10174 }
10175 }
10176 else
10185 /* Create the type. */
10187 {
10188 /* The user referred to a specialization of an alias
10189 template represented by GEN_TMPL.
10191 [temp.alias]/2 says:
10193 When a template-id refers to the specialization of an
10194 alias template, it is equivalent to the associated
10195 type obtained by substitution of its
10196 template-arguments for the template-parameters in the
10197 type-id of the alias template. */
10200 /* Note that the call above (by indirectly calling
10201 register_specialization in tsubst_decl) registers the
10202 TYPE_DECL representing the specialization of the alias
10203 template. So next time someone substitutes ARGLIST for
10204 the template parms into the alias template (GEN_TMPL),
10205 she'll get that TYPE_DECL back. */
10209 }
10211 {
10213 {
10224 }
10225 else
10226 {
10227 /* We don't want to call start_enum for this type, since
10228 the values for the enumeration constants may involve
10229 template parameters. And, no one should be interested
10230 in the enumeration constants for such a type. */
10233 }
10237 }
10239 {
10240 /* Lambda closures are regenerated in tsubst_lambda_expr, not
10241 instantiated here. */
10249 /* A local class. Make sure the decl gets registered properly. */
10256 /* This instantiation is another name for the primary
10257 template type. Set the TYPE_CANONICAL field
10258 appropriately. */
10262 }
10263 else
10266 /* If we called start_enum or pushtag above, this information
10267 will already be set up. */
10270 {
10277 }
10280 /* Although GEN_TMPL is the TEMPLATE_DECL, it has the same value
10281 of export flag. We want to propagate this because it might
10282 be a friend declaration that pushes a new hidden binding. */
10286 {
10292 {
10295 }
10296 }
10300 {
10304 {
10305 tree attributes
10313 }
10314 }
10316 /* Let's consider the explicit specialization of a member
10317 of a class template specialization that is implicitly instantiated,
10318 e.g.:
10319 template<class T>
10320 struct S
10321 {
10322 template<class U> struct M {}; //#0
10323 };
10325 template<>
10326 template<>
10327 struct S<int>::M<char> //#1
10328 {
10329 int i;
10330 };
10331 [temp.expl.spec]/4 says this is valid.
10333 In this case, when we write:
10334 S<int>::M<char> m;
10336 M is instantiated from the CLASSTYPE_TI_TEMPLATE of #1, not from
10337 the one of #0.
10339 When we encounter #1, we want to store the partial instantiation
10340 of M (template<class T> S<int>::M<T>) in its CLASSTYPE_TI_TEMPLATE.
10342 For all cases other than this "explicit specialization of member of a
10343 class template", we just want to store the most general template into
10344 the CLASSTYPE_TI_TEMPLATE of M.
10346 This case of "explicit specialization of member of a class template"
10347 only happens when:
10348 1/ the enclosing class is an instantiation of, and therefore not
10349 the same as, the context of the most general template, and
10350 2/ we aren't looking at the partial instantiation itself, i.e.
10351 the innermost arguments are not the same as the innermost parms of
10352 the most general template.
10354 So it's only when 1/ and 2/ happens that we want to use the partial
10355 instantiation of the member template in lieu of its most general
10356 template. */
10360 /* the enclosing class must be an instantiation... */
10363 {
10367 tree partial_inst_args =
10374 use_partial_inst_tmpl =
10375 /*...and we must not be looking at the partial instantiation
10376 itself. */
10378 partial_inst_args);
10379 }
10382 /* This case is easy; there are no member templates involved. */
10384 else
10385 {
10386 /* This is a full instantiation of a member template. Find
10387 the partial instantiation of which this is an instance. */
10389 /* Temporarily reduce by one the number of levels in the ARGLIST
10390 so as to avoid comparing the last set of arguments. */
10392 /* We don't use COMPLAIN in the following call because this isn't
10393 the immediate context of deduction. For instance, tf_partial
10394 could be set here as we might be at the beginning of template
10395 argument deduction when any explicitly specified template
10396 arguments are substituted into the function type. tf_partial
10397 could lead into trouble because we wouldn't find the partial
10398 instantiation that might have been created outside tf_partial
10399 context, because the levels of template parameters wouldn't
10400 match, because in a tf_partial context, tsubst doesn't reduce
10401 TEMPLATE_PARM_LEVEL. */
10404 /* FOUND is either a proper class type, or an alias
10405 template specialization. In the later case, it's a
10406 TYPE_DECL, resulting from the substituting of arguments
10407 for parameters in the TYPE_DECL of the alias template
10408 done earlier. So be careful while getting the template
10409 of FOUND. */
10411 ? found
10418 {
10419 /* If this partial instantiation is specialized, we want to
10420 use it for hash table lookup. */
10424 }
10425 }
10427 /* Build template info for the new specialization. */
10437 /* Note this use of the partial instantiation so we can check it
10438 later in maybe_process_partial_specialization. */
10446 /* Now that the type has been registered on the instantiations
10447 list, we set up the enumerators. Because the enumeration
10448 constants may involve the enumeration type itself, we make
10449 sure to register the type first, and then create the
10450 constants. That way, doing tsubst_expr for the enumeration
10451 constants won't result in recursive calls here; we'll find
10452 the instantiation and exit above. */
10456 /* If the type makes use of template parameters, the
10457 code that generates debugging information will crash. */
10460 /* Possibly limit visibility based on template args. */
10467 }
10468 }
10470 /* Return a TEMPLATE_ID_EXPR for the given variable template and ARGLIST. */
10472 tree
10474 {
10485 /* The type of the expression is NULL_TREE since the template-id could refer
10486 to an explicit or partial specialization. */
10488 }
10490 /* Instantiate a variable declaration from a TEMPLATE_ID_EXPR if it's
10491 not dependent. */
10493 tree
10495 {
10499 /* If the template or arguments are dependent, then we
10500 can't resolve the TEMPLATE_ID_EXPR yet. */
10506 {
10508 {
10509 auto_diagnostic_group d;
10512 }
10514 }
10517 }
10519 /* Construct a TEMPLATE_ID_EXPR for the given variable template TEMPL having
10520 TARGS template args, and instantiate it if it's not dependent. */
10522 tree
10524 tsubst_flags_t complain)
10525 {
10532 }
10534 /* If the set of template parameters PARMS contains a template parameter
10535 at the given LEVEL and INDEX, then return this parameter. Otherwise
10536 return NULL_TREE. */
10538 static tree
10540 {
10549 }
10551 /* Return the TREE_LIST for the template parameter from PARMS that positionally
10552 corresponds to the template parameter PARM, or else return NULL_TREE. */
10554 static tree
10556 {
10560 }
10562 /* As above, but pull out the actual parameter. */
10564 static tree
10566 {
10572 /* As in template_parm_to_arg. */
10575 else
10580 }
10581 \f
10582 struct pair_fn_data
10583 {
10584 tree_fn_t fn;
10585 tree_fn_t any_fn;
10587 /* True when we should also visit template parameters that occur in
10588 non-deduced contexts. */
10591 };
10593 /* Called from for_each_template_parm via walk_tree. */
10595 static tree
10597 {
10604 #define WALK_SUBTREE(NODE) \
10605 do \
10606 { \
10607 result = for_each_template_parm (NODE, fn, data, pfd->visited, \
10608 pfd->include_nondeduced_p, \
10609 pfd->any_fn); \
10610 if (result) goto out; \
10611 } \
10612 while (0)
10622 {
10626 /* Fall through. */
10632 else
10642 /* Since we're not going to walk subtrees, we have to do this
10643 explicitly here. */
10645 /* Fall through. */
10648 /* Check the return type. */
10651 /* Check the parameter types. Since default arguments are not
10652 instantiated until they are needed, the TYPE_ARG_TYPES may
10653 contain expressions that involve template parameters. But,
10654 no-one should be looking at them yet. And, once they're
10655 instantiated, they don't contain template parameters, so
10656 there's no point in looking at them then, either. */
10657 {
10658 tree parm;
10663 /* Since we've already handled the TYPE_ARG_TYPES, we don't
10664 want walk_tree walking into them itself. */
10666 }
10669 {
10673 }
10689 {
10692 }
10715 /* Record template parameters such as `T' inside `TT<T>'. */
10717 /* Fall through. */
10729 /* A template template parameter is encountered. */
10733 /* Already substituted template template parameter */
10738 /* A template-id in a TYPENAME_TYPE might be a deduced context after
10739 partial instantiation. */
10746 /* If there's no type, then this thing must be some expression
10747 involving template parameters. */
10757 /* These are non-deduced contexts. */
10779 }
10781 #undef WALK_SUBTREE
10783 /* We didn't find any template parameters we liked. */
10784 out:
10786 }
10788 /* For each TEMPLATE_TYPE_PARM, TEMPLATE_TEMPLATE_PARM,
10789 BOUND_TEMPLATE_TEMPLATE_PARM or TEMPLATE_PARM_INDEX in T,
10790 call FN with the parameter and the DATA.
10791 If FN returns nonzero, the iteration is terminated, and
10792 for_each_template_parm returns 1. Otherwise, the iteration
10793 continues. If FN never returns a nonzero value, the value
10794 returned by for_each_template_parm is 0. If FN is NULL, it is
10795 considered to be the function which always returns 1.
10797 If INCLUDE_NONDEDUCED_P, then this routine will also visit template
10798 parameters that occur in non-deduced contexts. When false, only
10799 visits those template parameters that can be deduced. */
10801 static tree
10805 tree_fn_t any_fn)
10806 {
10808 tree result;
10810 /* Set up. */
10816 /* Walk the tree. (Conceptually, we would like to walk without
10817 duplicates, but for_each_template_parm_r recursively calls
10818 for_each_template_parm, so we would need to reorganize a fair
10819 bit to use walk_tree_without_duplicates, so we keep our own
10820 visited list.) */
10823 else
10826 for_each_template_parm_r,
10830 /* Clean up. */
10832 {
10835 }
10838 }
10840 struct find_template_parameter_info
10841 {
10845 {}
10851 tree ctx_parms;
10858 };
10860 /* Appends the declaration of T to the list in DATA. */
10862 static int
10864 {
10867 /* Template parameters declared within the expression are not part of
10868 the parameter mapping. For example, in this concept:
10870 template<typename T>
10871 concept C = requires { <expr> } -> same_as<int>;
10873 the return specifier same_as<int> declares a new decltype parameter
10874 that must not be part of the parameter mapping. The same is true
10875 for generic lambda parameters, lambda template parameters, etc. */
10883 /* We want the underlying TEMPLATE_TEMPLATE_PARM, not the
10884 BOUND_TEMPLATE_TEMPLATE_PARM itself. */
10887 /* This template parameter might be an argument to a cached dependent
10888 specalization that was formed earlier inside some other template, in
10889 which case the parameter is not among the ones that are in-scope.
10890 Look in CTX_PARMS to find the corresponding in-scope template
10891 parameter, and use it instead. */
10895 /* Arguments like const T yield parameters like const T. This means that
10896 a template-id like X<T, const T> would yield two distinct parameters:
10897 T and const T. Adjust types to their unqualified versions. */
10901 {
10902 /* Append T to PARM_LIST. */
10906 }
10908 /* Verify the parameter we found has a valid index. */
10910 {
10916 }
10919 }
10921 /* Ensure that we recursively examine certain terms that are not normally
10922 visited in for_each_template_parm_r. */
10924 static int
10926 {
10929 #define WALK_SUBTREE(NODE) \
10930 do \
10931 { \
10932 for_each_template_parm (NODE, keep_template_parm, data, \
10933 &ftpi->visited, true, \
10934 any_template_parm_r); \
10935 } \
10936 while (0)
10938 /* A mention of a member alias/typedef is a use of all of its template
10939 arguments, including those from the enclosing class, so we don't use
10940 alias_template_specialization_p here. */
10946 {
10948 /* Type constraints of a placeholder type may contain parameters. */
10955 /* Search through references to variable templates. */
10965 /* If T is a member template that shares template parameters with
10966 ctx_parms, we need to mark all those parameters for mapping.
10967 To that end, it should suffice to just walk the DECL_CONTEXT of
10968 the template (assuming the template is not overly general). */
10973 {
10974 /* Look in the parms and body. */
10978 }
10983 /* The conversion-type-id of a conversion operator may be dependent. */
10994 }
10996 /* Keep walking. */
10998 }
11000 /* Look through T for template parameters. */
11002 tree
11004 {
11007 any_template_parm_r);
11008 }
11010 /* As above, but also recursively look into the default arguments of template
11011 parameters we found. Used for alias CTAD. */
11013 tree
11015 {
11018 /* Since newly found parms are added to the end of the list, we
11019 can just walk it until we reach the end. */
11021 {
11026 }
11028 }
11030 /* True if PARM was found by a previous call to find_in. PARM can be a
11031 TREE_LIST, a DECL_TEMPLATE_PARM_P, or a TEMPLATE_PARM_P. */
11033 bool
11035 {
11040 else
11044 }
11046 /* Returns a list of unique template parameters found within T, where CTX_PARMS
11047 are the template parameters in scope. */
11049 tree
11051 {
11058 }
11060 /* Returns true if T depends on any template parameter. */
11062 bool
11064 {
11068 /* Namespaces can't depend on any template parameters. */
11084 else
11086 }
11088 /* Returns true if T depends on any template parameter with level LEVEL. */
11090 bool
11092 {
11095 }
11097 /* Returns true if the signature of DECL depends on any template parameter from
11098 its enclosing class. */
11100 static bool
11102 {
11106 else
11115 {
11118 {
11123 template_parm_outer_level,
11133 }
11134 }
11138 }
11140 /* Returns true if the constraints of DECL depend on any template parameters
11141 from its enclosing scope. */
11143 bool
11145 {
11152 {
11155 else
11157 }
11163 }
11165 /* Returns TRUE iff INST is an instantiation we don't need to do in an
11166 ill-formed translation unit, i.e. a variable or function that isn't
11167 usable in a constant expression. */
11171 {
11177 }
11179 /* Returns TRUE iff we should refuse to instantiate DECL because it's
11180 neglectable and instantiated from within an erroneous instantiation. */
11182 static bool
11184 {
11190 /* Avoid instantiating members of an ill-formed class. */
11191 bool refuse
11196 {
11201 }
11204 {
11205 /* Don't warn about it not being defined. */
11207 tree clone;
11210 }
11212 }
11220 /* We're starting to instantiate D; record the template instantiation context
11221 at LOC for diagnostics and to restore it later. */
11223 bool
11225 {
11229 {
11230 /* Tell error.cc not to try to instantiate any templates. */
11233 "template instantiation depth exceeds maximum of %d"
11235 max_tinst_depth);
11237 }
11239 /* If the current instantiation caused problems, don't let it instantiate
11240 anything else. Do allow deduction substitution and decls usable in
11241 constant expressions. */
11243 {
11244 /* Avoid no_linkage_errors and unused function (and all other)
11245 warnings for this decl. */
11248 }
11250 /* When not -quiet, dump template instantiations other than functions, since
11251 announce_function will take care of those. */
11273 }
11275 /* We're starting substitution of TMPL<ARGS>; record the template
11276 substitution context for diagnostics and to restore it later. */
11278 bool
11280 {
11282 }
11284 /* We're starting to instantiate D; record INPUT_LOCATION and the
11285 template instantiation context for diagnostics and to restore it
11286 later. */
11288 bool
11290 {
11292 }
11294 /* Likewise, but record LOC as the program location. */
11296 bool
11298 {
11301 }
11303 /* We're done instantiating this template; return to the instantiation
11304 context. */
11306 void
11308 {
11309 /* Restore the filename and line number stashed away when we started
11310 this instantiation. */
11314 }
11316 /* We're instantiating a deferred template; restore the template
11317 instantiation context in which the instantiation was requested, which
11318 is one step out from LEVEL. Return the corresponding DECL or TYPE. */
11320 static tree
11322 {
11334 }
11336 /* Returns the TINST_LEVEL which gives the original instantiation
11337 context. */
11341 {
11347 }
11349 /* True iff T is a friend function declaration that is not itself a template
11350 and is not defined in a class template. */
11352 bool
11354 {
11357 {
11361 /* DECL_FRIEND_CONTEXT is set for a friend defined in class. */
11364 /* Non-templated friends in a class template are still represented with a
11365 TEMPLATE_DECL; check that its primary template is the befriending
11366 class. Note that DECL_PRIMARY_TEMPLATE is null for
11367 template <class T> friend A<T>::f(); */
11371 }
11372 else
11374 }
11376 /* DECL is a friend FUNCTION_DECL or TEMPLATE_DECL. ARGS is the
11377 vector of template arguments, as for tsubst.
11379 Returns an appropriate tsubst'd friend declaration. */
11381 static tree
11383 {
11384 tree new_friend;
11389 /* This was a friend declared with an explicit template
11390 argument list, e.g.:
11392 friend void f<>(T);
11394 to indicate that f was a template instantiation, not a new
11395 function declaration. Now, we have to figure out what
11396 instantiation of what template. */
11397 {
11399 tree new_args;
11400 tree tmpl;
11403 /* Friend functions are looked up in the containing namespace scope.
11404 We must enter that scope, to avoid finding member functions of the
11405 current class with same name. */
11419 tsk_none);
11421 }
11427 /* The NEW_FRIEND will look like an instantiation, to the
11428 compiler, but is not an instantiation from the point of view of
11429 the language. For example, we might have had:
11431 template <class T> struct S {
11432 template <class U> friend void f(T, U);
11433 };
11435 Then, in S<int>, template <class U> void f(int, U) is not an
11436 instantiation of anything. */
11440 {
11446 /* Substitute TEMPLATE_PARMS_CONSTRAINTS so that parameter levels will
11447 match in decls_match. */
11452 {
11454 /* As well as each TEMPLATE_PARM_CONSTRAINTS. */
11456 tf_warning_or_error);
11457 }
11458 }
11460 /* The mangled name for the NEW_FRIEND is incorrect. The function
11461 is not a template instantiation and should not be mangled like
11462 one. Therefore, we forget the mangling here; we'll recompute it
11463 later if we need it. */
11465 {
11468 }
11471 {
11472 tree old_decl;
11473 tree ns;
11475 /* We must save some information from NEW_FRIEND before calling
11476 duplicate decls since that function will free NEW_FRIEND if
11477 possible. */
11481 (new_friend_template_info
11488 {
11489 /* This declaration is a `primary' template. */
11494 }
11496 /* Inside pushdecl_namespace_level, we will push into the
11497 current namespace. However, the friend function should go
11498 into the namespace of the template. */
11508 {
11509 /* This new friend declaration matched an existing
11510 declaration. For example, given:
11512 template <class T> void f(T);
11513 template <class U> class C {
11514 template <class T> friend void f(T) {}
11515 };
11517 the friend declaration actually provides the definition
11518 of `f', once C has been instantiated for some type. So,
11519 old_decl will be the out-of-class template declaration,
11520 while new_friend is the in-class definition.
11522 But, if `f' was called before this point, the
11523 instantiation of `f' will have DECL_TI_ARGS corresponding
11524 to `T' but not to `U', references to which might appear
11525 in the definition of `f'. Previously, the most general
11526 template for an instantiation of `f' was the out-of-class
11527 version; now it is the in-class version. Therefore, we
11528 run through all specialization of `f', adding to their
11529 DECL_TI_ARGS appropriately. In particular, they need a
11530 new set of outer arguments, corresponding to the
11531 arguments for this class instantiation.
11533 The same situation can arise with something like this:
11535 friend void f(int);
11536 template <class T> class C {
11537 friend void f(T) {}
11538 };
11540 when `C<int>' is instantiated. Now, `f(int)' is defined
11541 in the class. */
11544 /* On the other hand, if the in-class declaration does
11545 *not* provide a definition, then we don't want to alter
11546 existing definitions. We can just leave everything
11547 alone. */
11548 ;
11549 else
11550 {
11554 /* Overwrite whatever template info was there before, if
11555 any, with the new template information pertaining to
11556 the declaration. */
11560 {
11561 /* We should have called reregister_specialization in
11562 duplicate_decls. */
11567 /* Instantiate it if the global has already been used. */
11571 }
11572 else
11573 {
11574 tree t;
11576 /* Indicate that the old function template is a partial
11577 instantiation. */
11585 /* Reassign any specializations already in the hash table
11586 to the new more general template, and add the
11587 additional template args. */
11591 {
11593 spec_entry elt;
11605 register_specialization
11608 }
11610 }
11611 }
11613 /* The information from NEW_FRIEND has been merged into OLD_DECL
11614 by duplicate_decls. */
11616 }
11618 /* We've just introduced a namespace-scope function in the purview
11619 without necessarily having opened the enclosing namespace, so
11620 make sure the namespace is in the purview now too. */
11625 }
11626 else
11627 {
11631 /* In the code
11632 template <class T> class C {
11633 template <class U> friend void C1<U>::f (); // case 1
11634 friend void C2<T>::f (); // case 2
11635 };
11636 we only need to make sure CONTEXT is a complete type for
11637 case 2. To distinguish between the two cases, we note that
11638 CONTEXT of case 1 remains dependent type after tsubst while
11639 this isn't true for case 2. */
11649 {
11651 /* do_friend adds the TEMPLATE_DECL for any member friend
11652 template even if it isn't a member template, i.e.
11653 template <class T> friend A<T>::f();
11654 Look through it in that case. */
11658 /* Check to see that the declaration is really present, and,
11659 possibly obtain an improved declaration. */
11664 }
11665 }
11668 }
11670 /* FRIEND_TMPL is a friend TEMPLATE_DECL. ARGS is the vector of
11671 template arguments, as for tsubst.
11673 Returns an appropriate tsubst'd friend type or error_mark_node on
11674 failure. */
11676 static tree
11678 {
11679 tree tmpl;
11682 {
11685 }
11690 else
11691 {
11694 }
11700 {
11701 /* The friend template has already been declared. Just
11702 check to see that the declarations match, and install any new
11703 default parameters. We must tsubst the default parameters,
11704 of course. We only need the innermost template parameters
11705 because that is all that redeclare_class_template will look
11706 at. */
11709 {
11713 tf_warning_or_error);
11723 }
11724 }
11725 else
11726 {
11727 /* The friend template has not already been declared. In this
11728 case, the instantiation of the template class will cause the
11729 injection of this template into the namespace scope. */
11733 {
11734 /* The new TMPL is not an instantiation of anything, so we
11735 forget its origins. We don't reset CLASSTYPE_TI_TEMPLATE
11736 for the new type because that is supposed to be the
11737 corresponding template decl, i.e., TMPL. */
11744 /* Substitute into and set the constraints on the new declaration. */
11746 {
11754 }
11756 /* Inject this template into the enclosing namspace scope. */
11758 }
11759 }
11763 else
11767 }
11769 /* Returns zero if TYPE cannot be completed later due to circularity.
11770 Otherwise returns one. */
11772 static int
11774 {
11784 else
11786 }
11791 /* Instantiate the contract statement. */
11793 static tree
11795 tree in_decl)
11796 {
11802 /* Rebuild the result variable. */
11804 {
11812 /* Make sure the postcondition is valid. */
11818 /* Make the variable available for lookup. */
11820 }
11822 /* Instantiate the condition. If the return type is undeduced, process
11823 the expression as if inside a template to avoid spurious type errors. */
11833 /* And the comment. */
11838 }
11840 /* Update T by instantiating its contract attribute. */
11842 static void
11845 {
11846 /* For non-specializations, adjust the current declaration to the most general
11847 version of in_decl. Because we defer the instantiation of contracts as long
11848 as possible, they are still written in terms of the parameters (and return
11849 type) of the most general template. */
11856 /* Get the contract to be instantiated. */
11859 /* Use the complete set of template arguments for instantiation. The
11860 contract may not have been instantiated and still refer to outer levels
11861 of template parameters. */
11864 /* For member functions, make this available for semantic analysis. */
11868 {
11872 }
11879 /* Rebuild the attribute. */
11881 }
11883 /* Rebuild the attribute list for DECL, substituting into contracts
11884 as needed. */
11886 void
11888 {
11891 {
11894 }
11896 }
11898 /* Instantiate a single dependent attribute T (a TREE_LIST), and return either
11899 T or a new TREE_LIST, possibly a chain in the case of a pack expansion. */
11901 static tree
11904 {
11907 /* Note that contract attributes are never substituted from this function.
11908 Their instantiation is triggered by regenerate_from_template_decl when
11909 we instantiate the body of the function. */
11917 {
11924 clauses
11928 else
11930 }
11934 {
11942 {
11947 {
11950 /* FIXME: The body of this loop should really be dispatching
11951 according to omp_ts_map[OMP_TS_CODE (TS)].tp_type instead
11952 of having hard-wired knowledge of specific selectors. */
11955 {
11963 }
11964 else
11965 {
11968 {
11973 {
11974 location_t loc
11976 match_loc);
11980 }
11982 {
11983 location_t loc
11985 match_loc);
11989 }
11991 }
11997 {
11998 bool allow_string
12008 {
12009 location_t loc
12011 match_loc);
12014 "integer expression or string "
12016 else
12020 }
12022 }
12023 }
12026 }
12028 }
12030 }
12031 /* If the first attribute argument is an identifier, don't
12032 pass it through tsubst. Attributes like mode, format,
12033 cleanup and several target specific attributes expect it
12034 unmodified. */
12036 {
12037 tree chain
12041 }
12043 {
12044 /* An attribute pack expansion. */
12053 {
12057 }
12059 }
12060 else
12068 }
12070 /* Instantiate any dependent attributes in ATTRIBUTES, returning either it
12071 unchanged or a new TREE_LIST chain. */
12073 static tree
12076 {
12081 {
12085 }
12089 {
12092 {
12095 {
12101 }
12102 }
12104 }
12107 }
12109 /* Apply any attributes which had to be deferred until instantiation
12110 time. DECL_P, ATTRIBUTES and ATTR_FLAGS are as cplus_decl_attributes;
12111 ARGS, COMPLAIN, IN_DECL are as tsubst. Returns true normally,
12112 false on error. */
12114 static bool
12117 {
12118 tree t;
12125 {
12129 /* DECL_ATTRIBUTES comes from copy_node in tsubst_decl, and is identical
12130 to our attributes parameter. */
12132 }
12133 else
12134 {
12136 /* TYPE_ATTRIBUTES was set up (with abi_tag and may_alias) in
12137 lookup_template_class_1, and should be preserved. */
12141 }
12143 /* save_template_attributes puts the dependent attributes at the beginning of
12144 the list; find the non-dependent ones. */
12150 /* Apply any non-dependent attributes. */
12156 /* And then any dependent ones. */
12160 {
12165 {
12168 }
12171 }
12173 /* cplus_decl_attributes can add some attributes implicitly. For templates,
12174 those attributes should have been added already when those templates were
12175 parsed, and shouldn't be added based on from which context they are
12176 first time instantiated. */
12179 optimization_default_node);
12182 NULL);
12188 }
12190 /* The template TMPL is being instantiated with the template arguments TARGS.
12191 Perform the access checks that we deferred when parsing the template. */
12193 static void
12195 {
12205 {
12213 /* Make access check error messages point to the location
12214 of the use of the typedef. */
12218 }
12219 }
12221 tree
12223 {
12227 tree typedecl;
12228 tree pbinfo;
12229 tree base_list;
12231 tree fn_context;
12240 /* Figure out which template is being instantiated. */
12244 /* Mark the type as in the process of being defined. */
12247 /* We may be in the middle of deferred access check. Disable
12248 it now. */
12251 /* Determine what specialization of the original template to
12252 instantiate. */
12257 {
12258 /* This TYPE is actually an instantiation of a partial
12259 specialization. We replace the innermost set of ARGS with
12260 the arguments appropriate for substitution. For example,
12261 given:
12263 template <class T> struct S {};
12264 template <class T> struct S<T*> {};
12266 and supposing that we are instantiating S<int*>, ARGS will
12267 presently be {int*} -- but we need {int}. */
12270 }
12271 else
12272 {
12275 }
12277 /* If the template we're instantiating is incomplete, then clearly
12278 there's nothing we can do. */
12280 {
12281 /* We can try again later. */
12284 }
12286 /* If we've recursively instantiated too many templates, stop. */
12294 /* Also avoid push_to_top_level for a lambda in an NSDMI. */
12299 else
12300 {
12303 }
12307 /* Use #pragma pack from the template context. */
12313 /* Set the input location to the most specialized template definition.
12314 This is needed if tsubsting causes an error. */
12328 {
12331 /* Adjust visibility for template arguments. */
12333 }
12339 /* We should never instantiate a nested class before its enclosing
12340 class; we need to look up the nested class by name before we can
12341 instantiate it, and that lookup should instantiate the enclosing
12342 class. */
12347 /* Defer access checking while we substitute into the types named in
12348 the base-clause. */
12351 {
12352 tree pbase_binfo;
12355 /* Substitute into each of the bases to determine the actual
12356 basetypes. */
12358 {
12359 tree base;
12365 {
12366 expanded_bases =
12373 }
12376 {
12378 /* Extract the already-expanded base class. */
12380 else
12381 /* Substitute to figure out the base class. */
12383 NULL_TREE);
12391 }
12392 }
12394 /* The list is now in reverse order; correct that. */
12396 }
12397 /* Now call xref_basetypes to set up all the base-class
12398 information. */
12406 /* Now that our base classes are set up, enter the scope of the
12407 class, so that name lookups into base classes, etc. will work
12408 correctly. This is precisely analogous to what we do in
12409 begin_class_definition when defining an ordinary non-template
12410 class, except we also need to push the enclosing classes. */
12413 /* Now check accessibility of the types named in its base-clause,
12414 relative to the scope of the class. */
12417 /* A vector to hold members marked with attribute used. */
12420 /* Now members are processed in the order of declaration. */
12423 {
12427 {
12429 {
12431 /* A closure type for a lambda in an NSDMI or default argument.
12432 Ignore it; it will be regenerated when needed. */
12435 /* If the member is a class template, we've
12436 already substituted its type. */
12446 {
12449 /* Now, install the tag. We don't use pushtag
12450 because that does too much work -- creating an
12451 implicit typedef, which we've already done. */
12456 }
12457 }
12459 {
12460 tree r;
12470 /* Instantiate members marked with attribute used. */
12476 }
12479 /* A closure type for a lambda in an NSDMI or default argument.
12481 else
12482 {
12483 /* Build new TYPE_FIELDS. */
12487 {
12488 tree r;
12493 /* The file and line for this declaration, to
12494 assist in error message reporting. Since we
12495 called push_tinst_level above, we don't need to
12496 restore these. */
12506 {
12507 /* A capture pack became multiple fields. */
12510 }
12513 {
12517 {
12518 /* In [temp.inst]:
12520 [t]he initialization (and any associated
12521 side-effects) of a static data member does
12522 not occur unless the static data member is
12523 itself used in a way that requires the
12524 definition of the static data member to
12525 exist.
12527 Therefore, we do not substitute into the
12528 initialized for the static data member here. */
12529 finish_static_data_member_decl
12535 /* Instantiate members marked with attribute used. */
12538 }
12540 {
12541 /* Determine whether R has a valid type and can be
12542 completed later. If R is invalid, then its type
12543 is replaced by error_mark_node. */
12549 {
12550 /* If R's type couldn't be completed and
12551 it isn't a flexible array member (whose
12552 type is incomplete by definition) give
12553 an error. */
12556 }
12561 {
12564 }
12568 }
12570 /* If it is a TYPE_DECL for a class-scoped
12571 ENUMERAL_TYPE, such a thing will already have
12572 been added to the field list by tsubst_enum
12573 in finish_member_declaration case above. */
12577 {
12580 }
12581 }
12582 }
12583 }
12584 }
12585 else
12586 {
12589 {
12590 /* Build new CLASSTYPE_FRIEND_CLASSES. */
12594 {
12595 /* template <class T> friend class C; */
12597 }
12599 {
12600 /* template <class T> friend class C::D; */
12605 }
12608 {
12609 /* This could be either
12611 friend class T::C;
12613 when dependent_type_p is false or
12615 template <class U> friend class T::C;
12617 otherwise. */
12618 /* Bump processing_template_decl in case this is something like
12619 template <class T> friend struct A<T>::B. */
12624 }
12626 /* friend class C<T>; */
12630 /* Otherwise it's
12632 friend class C;
12634 where C is already declared or
12636 friend class C<int>;
12638 We don't have to do anything in these cases. */
12642 }
12643 else
12644 {
12645 /* Build new DECL_FRIENDLIST. */
12646 tree r;
12648 /* The file and line for this declaration, to
12649 assist in error message reporting. Since we
12650 called push_tinst_level above, we don't need to
12651 restore these. */
12655 {
12658 }
12663 {
12666 }
12667 }
12668 }
12669 }
12672 {
12673 /* Restore these before substituting into the lambda capture
12674 initializers. */
12677 }
12679 /* Set the file and line number information to whatever is given for
12680 the class itself. This puts error messages involving generated
12681 implicit functions at a predictable point, and the same point
12682 that would be used for non-template classes. */
12689 /* Remember if instantiating this class ran into errors, so we can avoid
12690 instantiating member functions in limit_bad_template_recursion. We set
12691 this flag even if the problem was in another instantiation triggered by
12692 this one, as that will likely also cause trouble for member functions. */
12696 /* We don't instantiate default arguments for member functions. 14.7.1:
12698 The implicit instantiation of a class template specialization causes
12699 the implicit instantiation of the declarations, but not of the
12700 definitions or default arguments, of the class member functions,
12701 member classes, static data members and member templates.... */
12706 /* Now that we've gone through all the members, instantiate those
12707 marked with attribute used. We must do this in the context of
12708 the class -- not the context we pushed from, as that might be
12709 inside a template and change the behaviour of mark_used. */
12719 /* The vtable for a template class can be emitted in any translation
12720 unit in which the class is instantiated. When there is no key
12721 method, however, finish_struct_1 will already have added TYPE to
12722 the keyed_classes. */
12727 }
12729 tree
12731 {
12732 tree r;
12738 else
12739 {
12745 }
12748 }
12750 /* Given a function parameter pack TMPL_PARM and some function parameters
12751 instantiated from it at *SPEC_P, return a NONTYPE_ARGUMENT_PACK of them
12752 and set *SPEC_P to point at the next point in the list. */
12754 tree
12756 {
12757 /* Collect all of the extra "packed" parameters into an
12758 argument pack. */
12759 tree argpack;
12770 {
12771 /* The instantiation is still a parameter pack; don't wrap it in a
12772 NONTYPE_ARGUMENT_PACK. */
12775 }
12776 else
12777 {
12778 /* Fill in PARMVEC with all of the parameters. */
12782 {
12788 }
12790 /* Build the argument packs. */
12792 }
12796 }
12798 /* Give a chain SPEC_PARM of PARM_DECLs, pack them into a
12799 NONTYPE_ARGUMENT_PACK. */
12801 static tree
12803 {
12805 }
12807 /* Return 1 if the Ith element of the argument pack ARG_PACK is a
12808 pack expansion with no extra args, 2 if it has extra args, or 0
12809 if it is not a pack expansion. */
12811 static int
12813 {
12815 /* We're being called before this happens in tsubst_pack_expansion. */
12822 /* A decl pack is itself an expansion. */
12829 }
12832 /* Creates and return an ARGUMENT_PACK_SELECT tree node. */
12834 static tree
12836 {
12843 }
12845 /* This is a subroutine of tsubst_pack_expansion.
12847 It returns TRUE if we need to use the PACK_EXPANSION_EXTRA_ARGS
12848 mechanism to store the (non complete list of) arguments of the
12849 substitution and return a non substituted pack expansion, in order
12850 to wait for when we have enough arguments to really perform the
12851 substitution. */
12853 static bool
12855 tree parm_packs,
12858 {
12863 /* If one pack has an expansion and another pack has a normal
12864 argument or if one pack has an empty argument and an another
12865 one hasn't then tsubst_pack_expansion cannot perform the
12866 substitution and need to fall back on the
12867 PACK_EXPANSION_EXTRA mechanism. */
12871 {
12872 /* If all the actual packs are pack expansions, we can still
12873 subsitute directly. */
12875 {
12885 }
12887 }
12890 {
12894 parm_pack;
12896 {
12901 /* We can't substitute a pack expansion with extra args into
12902 our pattern. */
12906 else
12908 }
12911 {
12914 }
12915 }
12917 }
12919 /* [temp.variadic]/6 says that:
12921 The instantiation of a pack expansion [...]
12922 produces a list E1,E2, ..., En, where N is the number of elements
12923 in the pack expansion parameters.
12925 This subroutine of tsubst_pack_expansion produces one of these Ei.
12927 PATTERN is the pattern of the pack expansion. PARM_PACKS is a
12928 TREE_LIST in which each TREE_PURPOSE is a parameter pack of
12929 PATTERN, and each TREE_VALUE is its corresponding argument pack.
12930 INDEX is the index 'i' of the element Ei to produce. ARGS,
12931 COMPLAIN, and IN_DECL are the same parameters as for the
12932 tsubst_pack_expansion function.
12934 The function returns the resulting Ei upon successful completion,
12935 or error_mark_node.
12937 Note that this function possibly modifies the ARGS parameter, so
12938 it's the responsibility of the caller to restore it. */
12940 static tree
12942 tree parm_packs,
12944 tree args /* This parm gets
12946 tsubst_flags_t complain,
12947 tree in_decl)
12948 {
12949 tree t;
12952 /* For each parameter pack, change the substitution of the parameter
12953 pack to the ith argument in its argument pack, then expand the
12954 pattern. */
12956 {
12961 ith_elem_is_expansion |=
12964 /* Select the Ith argument from the pack. */
12968 {
12970 {
12975 }
12976 else
12978 }
12979 else
12980 {
12985 {
12987 /* Update the corresponding argument. */
12989 }
12990 else
12991 /* Re-use the ARGUMENT_PACK_SELECT. */
12993 }
12995 }
12997 /* Substitute into the PATTERN with the (possibly altered)
12998 arguments. */
13000 /* Expanding a fixed parameter pack from
13001 coerce_template_parameter_pack. */
13007 else
13008 {
13011 /* When expanding the fake auto... pack expansion from add_capture, we
13012 need to mark that the expansion is no longer a pack. */
13014 }
13016 /* If the Ith argument pack element is a pack expansion, then
13017 the Ith element resulting from the substituting is going to
13018 be a pack expansion as well. */
13023 }
13025 /* When the unexpanded parameter pack in a fold expression expands to an empty
13026 sequence, the value of the expression is as follows; the program is
13027 ill-formed if the operator is not listed in this table.
13029 && true
13030 || false
13031 , void() */
13033 tree
13035 {
13039 {
13048 }
13054 }
13056 /* Given a fold-expression T and a current LEFT and RIGHT operand,
13057 form an expression that combines the two terms using the
13058 operator of T. */
13060 static tree
13062 {
13067 // Handle compound assignment operators.
13074 {
13083 complain);
13084 }
13085 }
13087 /* Substitute ARGS into the pack of a fold expression T. */
13091 {
13093 }
13095 /* Substitute ARGS into the pack of a fold expression T. */
13099 {
13101 }
13103 /* Expand a PACK of arguments into a grouped as left fold.
13104 Given a pack containing elements A0, A1, ..., An and an
13105 operator @, this builds the expression:
13107 ((A0 @ A1) @ A2) ... @ An
13109 Note that PACK must not be empty.
13111 The operator is defined by the original fold expression T. */
13113 static tree
13115 {
13118 {
13121 }
13123 }
13125 /* Substitute into a unary left fold expression. */
13127 static tree
13129 tree in_decl)
13130 {
13135 {
13139 }
13142 else
13144 }
13146 /* Substitute into a binary left fold expression.
13148 Do ths by building a single (non-empty) vector of argumnts and
13149 building the expression from those elements. */
13151 static tree
13153 tree in_decl)
13154 {
13163 {
13168 }
13176 }
13178 /* Expand a PACK of arguments into a grouped as right fold.
13179 Given a pack containing elementns A0, A1, ..., and an
13180 operator @, this builds the expression:
13182 A0@ ... (An-2 @ (An-1 @ An))
13184 Note that PACK must not be empty.
13186 The operator is defined by the original fold expression T. */
13188 tree
13190 {
13191 // Build the expression.
13195 {
13198 }
13200 }
13202 /* Substitute into a unary right fold expression. */
13204 static tree
13206 tree in_decl)
13207 {
13212 {
13216 }
13219 else
13221 }
13223 /* Substitute into a binary right fold expression.
13225 Do ths by building a single (non-empty) vector of arguments and
13226 building the expression from those elements. */
13228 static tree
13230 tree in_decl)
13231 {
13240 {
13245 }
13254 }
13256 /* Walk through the pattern of a pack expansion, adding everything in
13257 local_specializations to a list. */
13259 class el_data
13260 {
13262 /* Set of variables declared within the pattern. */
13264 /* Set of AST nodes that have been visited by the traversal. */
13266 /* List of local_specializations used within the pattern. */
13267 tree extra;
13268 tsubst_flags_t complain;
13269 /* True iff we don't want to walk into unevaluated contexts. */
13271 /* The unevaluated contexts that we avoided walking. */
13276 };
13277 static tree
13279 {
13286 {
13290 }
13293 /* Remember local typedefs (85214). */
13297 {
13303 {
13306 decl2
13312 {
13315 }
13316 }
13317 }
13319 {
13320 /* Since we defer implicit capture, look in the parms and body. */
13326 }
13328 {
13330 /* Don't mess with variables declared within the pattern. */
13333 {
13334 /* Maybe pull out the PARM_DECL for a partial instantiation. */
13337 {
13343 }
13345 {
13346 /* Handle lambda capture here, since we aren't doing any
13347 substitution now, and so tsubst_copy won't call
13348 process_outer_var_ref. */
13352 {
13358 {
13359 /* Make a new NONTYPE_ARGUMENT_PACK of the capture
13360 proxies. */
13362 {
13367 }
13369 }
13370 }
13371 }
13372 }
13376 }
13378 }
13379 static tree
13381 {
13383 /* Walk the pattern twice, ignoring unevaluated operands the first time
13384 around, so that if a local specialization appears in both an evaluated
13385 and unevaluated context we prefer to process it in the evaluated context
13386 (since e.g. process_outer_var_ref is a no-op inside an unevaluated
13387 context). */
13390 /* Now walk the unevaluated contexts we skipped the first time around. */
13393 {
13396 }
13398 }
13400 /* Extract any uses of local_specializations from PATTERN and add them to ARGS
13401 for use in PACK_EXPANSION_EXTRA_ARGS. */
13403 tree
13405 {
13406 /* Make a copy of the extra arguments so that they won't get changed
13407 out from under us. */
13413 }
13415 /* Apply any local specializations from PACK_EXPANSION_EXTRA_ARGS and add the
13416 normal template args to ARGS. */
13418 tree
13420 {
13422 {
13424 {
13425 /* The partial instantiation involved local declarations collected in
13426 extract_local_specs; map from the general template to our local
13427 context. */
13433 /* else inst is already a full instantiation of the pack. */
13435 }
13438 }
13440 {
13441 /* This can happen after dependent substitution into a
13442 requires-expr or a lambda that uses constexpr if. */
13445 }
13446 else
13449 }
13451 /* Substitute ARGS into T, which is an pack expansion
13452 (i.e. TYPE_PACK_EXPANSION or EXPR_PACK_EXPANSION). Returns a
13453 TREE_VEC with the substituted arguments, a PACK_EXPANSION_* node
13454 (if only a partial substitution could be performed) or
13455 ERROR_MARK_NODE if there was an error. */
13456 tree
13458 tree in_decl)
13459 {
13460 tree pattern;
13464 tree result;
13471 /* Add in any args remembered from an earlier partial instantiation. */
13476 /* Determine the argument packs that will instantiate the parameter
13477 packs used in the expansion expression. While we're at it,
13478 compute the number of arguments to be expanded and make sure it
13479 is consistent. */
13482 {
13489 {
13494 else
13496 }
13498 {
13500 {
13503 parm_pack);
13505 }
13508 }
13510 {
13511 /* We know we have correct local_specializations if this
13512 expansion is at function scope, or if we're dealing with a
13513 local parameter in a requires expression; for the latter,
13514 tsubst_requires_expr set it up appropriately. */
13517 else
13518 /* We can't rely on local_specializations for a parameter
13519 name used later in a function declaration (such as in a
13520 late-specified return type). Even if it exists, it might
13521 have the wrong value for a recursive call. */
13525 {
13526 /* This parameter pack was used in an unevaluated context. Just
13527 make a dummy decl, since it's only used for its type. */
13532 /* Partial instantiation of the parm_pack, we can't build
13533 up an argument pack yet. */
13535 else
13537 }
13539 /* This argument pack isn't fully instantiated yet. */
13541 }
13543 {
13547 }
13548 else
13549 {
13558 }
13565 /* This can only happen if we forget to expand an argument
13566 pack somewhere else. Just return an error, silently. */
13567 {
13571 }
13574 {
13578 /* Don't bother trying to do a partial substitution with
13579 incomplete packs; we'll try again after deduction. */
13586 {
13591 pattern);
13592 else
13594 pattern);
13596 }
13598 /* Keep track of the parameter packs and their corresponding
13599 argument packs. */
13602 }
13603 else
13604 {
13605 /* We can't substitute for this parameter pack. We use a flag as
13606 well as the missing_level counter because function parameter
13607 packs don't have a level. */
13610 }
13611 }
13613 /* If the expansion is just T..., return the matching argument pack, unless
13614 we need to call convert_from_reference on all the elements. This is an
13615 important optimization; see c++/68422. */
13618 {
13621 /* If the argument pack is a single pack expansion, pull it out. */
13624 {
13628 /* Except if this isn't a simple sizeof...(T) which gets sZ
13630 else
13632 }
13634 /* Types need no adjustment, nor does sizeof..., and if we still have
13635 some pack expansion args we won't do anything yet. */
13640 /* Also optimize expression pack expansions if we can tell that the
13641 elements won't have reference type. */
13647 /* Otherwise use the normal path so we get convert_from_reference. */
13648 }
13650 /* We cannot expand this expansion expression, because we don't have
13651 all of the argument packs we need. */
13653 {
13654 /* We got some full packs, but we can't substitute them in until we
13655 have values for all the packs. So remember these until then. */
13661 }
13663 /* If NEED_LOCAL_SPECIALIZATIONS then we're in a late-specified return
13664 type, so create our own local specializations map; the current map is
13665 either NULL or (in the case of recursive unification) might have
13666 bindings that we don't want to use or alter. */
13671 {
13672 /* There were no real arguments, we're just replacing a parameter
13673 pack with another version of itself. Substitute into the
13674 pattern and return a PACK_EXPANSION_*. The caller will need to
13675 deal with that. */
13678 else
13684 {
13685 /* This is a fake auto... pack expansion created in add_capture with
13686 _PACKS that don't appear in the pattern. Copy one over. */
13693 }
13695 }
13699 /* For each argument in each argument pack, substitute into the
13700 pattern. */
13704 {
13706 i,
13708 in_decl);
13711 {
13714 }
13715 }
13717 /* Update ARGS to restore the substitution from parameter packs to
13718 their argument packs. */
13720 {
13727 else
13728 {
13736 /* Update the corresponding argument. */
13740 else
13742 }
13743 }
13745 /* If the dependent pack arguments were such that we end up with only a
13746 single pack expansion again, there's no need to keep it in a TREE_VEC. */
13752 }
13754 /* Make an argument pack out of the TREE_VEC VEC. */
13756 static tree
13758 {
13759 tree pack;
13763 else
13764 {
13767 }
13770 }
13772 /* Return an exact copy of template args T that can be modified
13773 independently. */
13775 static tree
13777 {
13785 {
13790 }
13796 }
13798 /* Substitute ARGS into the *_ARGUMENT_PACK orig_arg. */
13800 tree
13802 tree in_decl)
13803 {
13804 /* This flag is used only during deduction, and we don't expect to
13805 substitute such ARGUMENT_PACKs. */
13808 /* Substitute into each of the arguments. */
13817 /* If we're substituting into a generic ARGUMENT_PACK for a variadic
13818 template parameter, we might be able to avoid allocating a new
13819 ARGUMENT_PACK and reuse the corresponding ARGUMENT_PACK from ARGS
13820 if the substituted result is identical to it. */
13822 {
13829 {
13832 }
13833 }
13835 tree new_arg;
13837 {
13840 }
13841 else
13842 {
13845 }
13848 }
13850 /* Substitute ARGS into the vector or list of template arguments T. */
13852 tree
13854 {
13858 /* In "sizeof(X<I>)" we need to evaluate "I". */
13859 cp_evaluated ev;
13865 /* True iff the substituted result is identical to T. */
13869 {
13871 tree new_arg;
13878 {
13879 /* Substitute into an expansion expression. */
13883 /* Add to the expanded length adjustment the number of
13884 expanded arguments. We subtract one from this
13885 measurement, because the argument pack expression
13886 itself is already counted as 1 in
13887 LEN. EXPANDED_LEN_ADJUST can actually be negative, if
13888 the argument pack is empty. */
13890 }
13893 else
13902 }
13909 /* If ARGS and T are both multi-level, the substituted result may be
13910 identical to ARGS. */
13915 /* If T appears to be a vector of generic template arguments, the
13916 substituted result may be identical to the corresponding level
13917 from ARGS. */
13919 {
13924 }
13926 /* If the substituted result is identical to MAYBE_REUSE, return
13927 it and avoid allocating a new TREE_VEC, as an optimization. */
13933 /* If T consists of only a pack expansion for which substitution yielded
13934 a TREE_VEC of the expanded elements, then reuse that TREE_VEC instead
13935 of effectively making a copy. */
13941 /* Make space for the expanded arguments coming from template
13942 argument packs. */
13944 /* T can contain TREE_VECs. That happens if T contains the
13945 arguments for a member template.
13946 In that case each TREE_VEC in T represents a level of template
13947 arguments, and T won't carry any non defaulted argument count.
13948 It will rather be the nested TREE_VECs that will carry one.
13949 In other words, T carries a non defaulted argument count only
13950 if it doesn't contain any nested TREE_VEC. */
13952 {
13956 }
13960 {
13965 {
13966 /* Now expand the template argument pack "in place". */
13969 }
13970 else
13971 {
13973 out++;
13974 }
13975 }
13979 }
13981 /* Substitute ARGS into one level PARMS of template parameters. */
13983 static tree
13985 {
13992 {
14000 }
14003 }
14005 /* Return the result of substituting ARGS into the template parameters
14006 given by PARMS. If there are m levels of ARGS and m + n levels of
14007 PARMS, then the result will contain n levels of PARMS. For
14008 example, if PARMS is `template <class T> template <class U>
14009 template <T*, U, class V>' and ARGS is {{int}, {double}} then the
14010 result will be `template <int*, double, class V>'. */
14012 static tree
14014 {
14018 /* When substituting into a template, we must set
14019 PROCESSING_TEMPLATE_DECL as the template parameters may be
14020 dependent if they are based on one-another, and the dependency
14021 predicates are short-circuit outside of templates. */
14028 {
14037 }
14042 }
14044 /* Return the result of substituting ARGS into one template parameter
14045 given by T. T Must be a TREE_LIST which TREE_VALUE is the template
14046 parameter and which TREE_PURPOSE is the default argument of the
14047 template parameter. */
14049 static tree
14051 {
14074 }
14076 /* Substitute in-place the TEMPLATE_PARM_CONSTRAINTS of each template
14077 parameter in PARMS for sake of declaration matching. */
14079 static void
14081 tsubst_flags_t complain)
14082 {
14085 {
14091 }
14093 }
14095 /* Substitute the ARGS into the indicated aggregate (or enumeration)
14096 type T. If T is not an aggregate or enumeration type, it is
14097 handled as if by tsubst. IN_DECL is as for tsubst. If
14098 ENTERING_SCOPE is nonzero, T is the context for a template which
14099 we are presently tsubst'ing. Return the substituted value. */
14101 static tree
14103 tree args,
14104 tsubst_flags_t complain,
14105 tree in_decl,
14107 {
14111 /* Handle typedefs via tsubst so that they get consistently reused. */
14113 {
14118 /* The effect of entering_scope is that for a dependent specialization
14119 A<T>, lookup_template_class prefers to return A's primary template
14120 type instead of the implicit instantiation. So when entering_scope,
14121 we mirror this behavior by inspecting TYPE_CANONICAL appropriately,
14122 taking advantage of the fact that lookup_template_class links the two
14123 types by setting TYPE_CANONICAL of the latter to the former. */
14132 }
14135 {
14143 }
14144 }
14146 /* The part of tsubst_aggr_type that's shared with the RECORD_, UNION_
14147 and ENUMERAL_TYPE cases of tsubst. */
14149 static tree
14151 tree args,
14152 tsubst_flags_t complain,
14153 tree in_decl,
14155 {
14157 {
14160 /* Figure out what arguments are appropriate for the
14161 type we are trying to find. For example, given:
14163 template <class T> struct S;
14164 template <class T, class U> void f(T, U) { S<U> su; }
14166 and supposing that we are instantiating f<int, double>,
14167 then our ARGS will be {int, double}, but, when looking up
14168 S we only want {double}. */
14177 }
14178 else
14179 /* This is not a template type, so there's nothing to do. */
14181 }
14183 /* Map from a FUNCTION_DECL to a vec of default argument instantiations,
14184 indexed in reverse order of the parameters. */
14188 /* Return a reference to the vec* of defarg insts for FN. */
14192 {
14196 tree_vec_map **slot
14199 {
14202 }
14204 }
14206 /* Substitute into the default argument ARG (a default argument for
14207 FN), which has the indicated TYPE. */
14209 tree
14211 tsubst_flags_t complain)
14212 {
14215 /* This can happen in invalid code. */
14219 /* Shortcut {}. */
14234 /* Remember the location of the pointer to the vec rather than the location
14235 of the particular element, in case the vec grows in tsubst_expr. */
14237 /* Index in reverse order to avoid allocating space for initial parameters
14238 that don't have default arguments. */
14245 /* This default argument came from a template. Instantiate the
14246 default argument here, not in tsubst. In the case of
14247 something like:
14249 template <class T>
14250 struct S {
14251 static T t();
14252 void f(T = t());
14253 };
14255 we must be careful to do name lookup in the scope of S<T>,
14256 rather than in the current class. */
14260 /* So in_immediate_context knows this is a default argument. */
14264 /* The default argument expression may cause implicitly defined
14265 member functions to be synthesized, which will result in garbage
14266 collection. We must treat this situation as if we were within
14267 the body of function so as to avoid collecting live data on the
14268 stack. */
14275 /* Make sure the default argument is reasonable. */
14292 }
14294 /* Substitute into all the default arguments for FN. */
14296 static void
14298 {
14299 tree arg;
14300 tree tmpl_args;
14304 /* If this function is not yet instantiated, we certainly don't need
14305 its default arguments. */
14308 /* Don't do this again for clones. */
14314 arg;
14320 complain);
14321 }
14323 /* Hash table mapping a FUNCTION_DECL to its dependent explicit-specifier. */
14326 /* Store a pair to EXPLICIT_SPECIFIER_MAP. */
14328 void
14330 {
14335 }
14337 /* Lookup an element in EXPLICIT_SPECIFIER_MAP. */
14339 tree
14341 {
14343 }
14345 /* Given T, a FUNCTION_TYPE or METHOD_TYPE, construct and return a corresponding
14346 FUNCTION_TYPE or METHOD_TYPE whose return type is RETURN_TYPE, argument types
14347 are ARG_TYPES, and exception specification is RAISES, and otherwise is
14348 identical to T. */
14350 static tree
14353 {
14356 tree new_type;
14358 {
14361 }
14362 else
14363 {
14365 /* Don't pick up extra function qualifiers from the basetype. */
14368 {
14369 /* [temp.deduct]
14371 Type deduction may fail for any of the following
14372 reasons:
14374 -- Attempting to create "pointer to member of T" when T
14375 is not a class type. */
14378 r);
14380 }
14384 }
14390 }
14392 /* Check if the function type of DECL, a FUNCTION_DECL, agrees with the type of
14393 each of its formal parameters. If there is a disagreement then rebuild
14394 DECL's function type according to its formal parameter types, as part of a
14395 resolution for Core issues 1001/1322. */
14397 static void
14399 {
14402 {
14405 {
14409 {
14412 }
14416 }
14417 }
14428 {
14433 }
14435 {
14445 }
14453 }
14455 /* Subroutine of tsubst_decl for the case when T is a FUNCTION_DECL. */
14457 static tree
14460 {
14465 /* Nobody should be tsubst'ing into non-template functions. */
14470 {
14473 }
14475 {
14476 /* If T is not dependent, just return it. */
14481 /* A non-templated friend doesn't get DECL_TEMPLATE_INFO. */
14485 /* Calculate the most general template of which R is a
14486 specialization. */
14489 /* We're substituting a lambda function under tsubst_lambda_expr but not
14490 directly from it; find the matching function we're already inside.
14491 But don't do this if T is a generic lambda with a single level of
14492 template parms, as in that case we're doing a normal instantiation. */
14498 /* Calculate the complete set of arguments used to
14499 specialize R. */
14501 {
14503 (DECL_TEMPLATE_RESULT
14509 /* Check to see if we already have this specialization. */
14512 /* The spec for these args might be a partial instantiation of the
14513 template, but here what we want is the FUNCTION_DECL. */
14515 }
14516 else
14518 }
14519 else
14520 {
14521 /* This special case arises when we have something like this:
14523 template <class T> struct S {
14524 friend void f<int>(int, double);
14525 };
14527 Here, the DECL_TI_TEMPLATE for the friend declaration
14528 will be an IDENTIFIER_NODE. We are being called from
14529 tsubst_friend_function, and we want only to create a
14530 new decl (R) with appropriate types so that we can call
14531 determine_specialization. */
14532 friend_case:
14535 }
14542 /* If this is a static or xobj lambda, remove the 'this' pointer added in
14543 tsubst_lambda_expr now that we know the closure type. */
14557 /* If we hit excessive deduction depth, the type is bogus even if
14558 it isn't error_mark_node, so don't build a decl. */
14562 /* We do NOT check for matching decls pushed separately at this
14563 point, as they may not represent instantiations of this
14564 template, and in any case are considered separate under the
14565 discrete model. */
14569 /* Clear out the mangled name and RTL for the instantiation. */
14572 /* Leave DECL_INITIAL set on deleted instantiations. */
14578 /* Handle explicit(dependent-expr). */
14580 {
14588 else
14589 {
14592 }
14593 }
14595 /* OpenMP UDRs have the only argument a reference to the declared
14596 type. We want to diagnose if the declared type is a reference,
14597 which is invalid, but as references to references are usually
14598 quietly merged, diagnose it here. */
14600 {
14601 tree argtype
14606 "reference type %qT in "
14610 argtype);
14611 }
14614 /* Type-conversion operator. Reconstruct the name, in
14615 case it's the name of one of the template's parameters. */
14625 {
14630 }
14639 /* If this is an instantiation of a function with internal
14640 linkage, we already know what object file linkage will be
14641 assigned to the instantiation. */
14650 /* We'll re-clone as appropriate in instantiate_template. */
14653 /* If we aren't complaining now, return on error before we register
14654 the specialization so that we'll complain eventually. */
14660 /* If we are looking at an xobj lambda, we might need to check the type of
14661 its xobj parameter. */
14663 {
14670 /* If a lambda has an empty capture clause, an xobj parameter of
14673 /* If we are coming from tsubst_lambda_expr we might not have
14674 substituted into our xobj parameter yet. We can't error out until
14675 we know what the type really is so do nothing...
14676 ...but if we are instantiating the call op for real and we don't
14677 have a real type then something has gone incredibly wrong. */
14679 else
14680 {
14681 /* We have a lambda with captures, and know the type of the xobj
14682 parameter, time to check it. */
14685 {
14686 /* This error does not emit when the lambda's call operator
14687 template is instantiated by taking its address, such as in
14688 the following case:
14690 auto f = [x = 0](this auto&&){};
14691 int (*fp)(int&) = &decltype(f)::operator();
14693 It only emits when explicitly calling the call operator with
14694 an explicit template parameter:
14696 template<typename T>
14697 struct S : T {
14698 using T::operator();
14699 operator int() const {return {};}
14700 };
14702 auto s = S{[x = 0](this auto&&) {}};
14703 s.operator()<int>();
14705 This is due to resolve_address_of_overloaded_function being
14706 deficient at reporting candidates when overload resolution
14707 fails.
14709 This diagnostic will be active in the first case if/when
14710 resolve_address_of_overloaded_function is fixed to properly
14711 emit candidates upon failure to resolve to an overload. */
14716 }
14717 }
14718 }
14720 /* Associate the constraints directly with the instantiation. We
14721 don't substitute through the constraints; that's only done when
14722 they are checked. */
14735 /* Set up the DECL_TEMPLATE_INFO for R. There's no need to do
14736 this in the special friend case mentioned above where
14737 GEN_TMPL is NULL. */
14739 {
14745 {
14746 tree new_r
14749 /* We instantiated this while substituting into
14750 the type earlier (template/friend54.C). */
14752 }
14754 /* We're not supposed to instantiate default arguments
14755 until they are called, for a template. But, for a
14756 declaration like:
14758 template <class T> void f ()
14759 { extern void g(int i = T()); }
14761 we should do the substitution when the template is
14762 instantiated. We handle the member function case in
14763 instantiate_class_template since the default arguments
14764 might refer to other members of the class. */
14769 }
14771 {
14774 }
14775 else
14778 /* Copy the list of befriending classes. */
14782 {
14786 }
14789 {
14793 /* If this is an instantiation of a member template, clone it.
14794 If it isn't, that'll be handled by
14795 clone_constructors_and_destructors. */
14798 }
14804 /* Possibly limit visibility based on template args. */
14807 {
14811 }
14826 }
14828 /* Subroutine of tsubst_decl for the case when T is a TEMPLATE_DECL. */
14830 static tree
14833 {
14834 /* We can get here when processing a member function template,
14835 member class template, or template template parameter. */
14838 tree spec;
14839 tree tmpl_args;
14841 tree r;
14845 {
14846 /* Template template parameter is treated here. */
14850 /* If we get a real template back, return it. This can happen in
14851 the context of most_specialized_partial_spec. */
14854 else
14855 /* The new TEMPLATE_DECL was built in
14856 reduce_template_parm_level. */
14859 }
14862 {
14863 /* We might already have an instance of this template.
14864 The ARGS are for the surrounding class type, so the
14865 full args contain the tsubst'd args for the context,
14866 plus the innermost args from the template decl. */
14870 /* Because this is a template, the arguments will still be
14871 dependent, even after substitution. If
14872 PROCESSING_TEMPLATE_DECL is not set, the dependency
14873 predicates will short-circuit. */
14881 /* If this is a default template template argument,
14882 tsubst might not have changed anything. */
14889 {
14891 /* Type partial instantiations are stored as the type by
14892 lookup_template_class_1, not here as the template. */
14897 }
14898 }
14900 /* Make a new template decl. It will be similar to the
14901 original, but will record the current template arguments.
14902 We also create a new function declaration, which is just
14903 like the old one, but points to this new template, rather
14904 than the old one. */
14909 // Build new template info linking to the original template decl.
14911 {
14914 }
14915 else
14918 /* The template parameters for this new template are all the
14919 template parameters for the old template, except the
14920 outermost level of parameters. */
14923 = current_template_parms
14924 = (lambda_tparms
14925 ? lambda_tparms
14927 complain));
14935 else
14936 {
14938 {
14941 }
14945 else
14947 }
14953 {
14954 /* For a partial specialization, we need to keep pointing to
14955 the primary template. */
14957 {
14960 }
14964 }
14966 {
14969 }
14970 else
14971 {
14973 /* Set DECL_TI_ARGS to the full set of template arguments,
14974 which tsubst_function_decl / tsubst_decl didn't do due to
14975 use_spec_table=false. */
14978 }
14985 {
14986 /* Propagate module information from the decl. */
14989 /* If this is a constrained template, the above tsubst of
14990 inner can find the unconstrained template, which may have
14991 come from an import. This is ok, because we don't
14992 register this instantiation (see below). */
14994 || (TEMPLATE_PARMS_CONSTRAINTS
14996 }
15007 {
15008 /* Record this non-type partial instantiation. */
15009 /* FIXME we'd like to always register the TEMPLATE_DECL, or always
15010 the DECL_TEMPLATE_RESULT, but it seems the modules code relies
15011 on this current behavior. */
15014 else
15016 }
15019 }
15021 /* True if FN is the op() for a lambda in an uninstantiated template. */
15023 bool
15025 {
15030 }
15032 /* True if FN is the substitution (via tsubst_lambda_expr) of a function for
15033 which the above is true. */
15035 bool
15037 {
15043 }
15045 /* Return the LAMBDA_EXPR from which T was ultimately regenerated.
15046 If T is not a regenerated LAMBDA_EXPR, return T. */
15048 tree
15050 {
15054 }
15056 /* Return the set of template arguments used to regenerate the lambda T
15057 from its most general lambda. */
15059 tree
15061 {
15067 else
15069 }
15071 /* We're instantiating a variable from template function TCTX. Return the
15072 corresponding current enclosing scope. We can match them up using
15073 DECL_SOURCE_LOCATION because lambdas only ever have one source location, and
15074 the DECL_SOURCE_LOCATION for a function instantiation is updated to match
15075 the template definition in regenerate_decl_from_template. */
15077 static tree
15079 {
15082 /* We shouldn't ever need to do this for other artificial functions. */
15089 }
15091 /* Substitute the ARGS into the T, which is a _DECL. Return the
15092 result of the substitution. Issue error and warning messages under
15093 control of COMPLAIN. The flag USE_SPEC_TABLE controls if we look up
15094 and insert into the specializations table or if we can assume it's
15095 the caller's responsibility; this is used by instantiate_template
15096 to avoid doing some redundant work. */
15098 static tree
15101 {
15102 #define RETURN(EXP) do { r = (EXP); goto out; } while(0)
15103 location_t saved_loc;
15111 /* Set the filename and linenumber to improve error-reporting. */
15116 {
15125 use_spec_table);
15129 {
15137 {
15138 /* If there is a local specialization that isn't a
15139 parameter pack, it means that we're doing a "simple"
15140 substitution from inside tsubst_pack_expansion. Just
15141 return the local specialization (which will be a single
15142 parm). */
15149 /* Expand the TYPE_PACK_EXPANSION that provides the types for
15150 the parameters in this function parameter pack. */
15154 {
15157 /* Zero-length parameter packs are boring. Just substitute
15158 into the chain. */
15162 }
15163 else
15164 {
15165 /* All we did was update the type. Make a note of that. */
15168 }
15169 }
15171 /* Loop through all of the parameters we'll build. When T is
15172 a function parameter pack, LEN is the number of expanded
15173 types in EXPANDED_TYPES; otherwise, LEN is 1. */
15176 {
15183 /* We're on the Ith parameter of the function parameter
15184 pack. */
15185 {
15186 /* Get the Ith type. */
15189 /* Rename the parameter to include the index. */
15192 }
15194 /* We're dealing with a normal parameter. */
15202 {
15205 else
15208 }
15219 /* Keep track of the first new parameter we
15220 generate. That's what will be returned to the
15221 caller. */
15225 /* Build a proper chain of parameters when substituting
15226 into a function parameter pack. */
15229 }
15231 /* If cp_unevaluated_operand is set, we're just looking for a
15232 single dummy parameter, so don't keep going. */
15237 /* FIRST_R contains the start of the chain we've built. */
15239 }
15243 {
15250 {
15251 /* This field is a lambda capture pack. Return a TREE_VEC of
15252 the expanded fields to instantiate_class_template_1. */
15256 {
15259 }
15260 else
15261 {
15262 /* All we did was update the type. Make a note of that. */
15265 }
15266 }
15269 {
15272 {
15276 }
15286 /* For bit-fields, DECL_BIT_FIELD_REPRESENTATIVE gives the
15287 number of bits. */
15292 {
15293 /* Set up DECL_TEMPLATE_INFO so that we can get at the
15294 NSDMI in perform_member_init. Still set DECL_INITIAL
15295 so that we know there is one. */
15300 }
15301 /* We don't have to set DECL_CONTEXT here; it is set by
15302 finish_member_declaration. */
15311 }
15315 }
15319 /* We reach here only for member using decls. We also need to check
15320 uses_template_parms because DECL_DEPENDENT_P is not set for a
15321 using-declaration that designates a member of the current
15322 instantiation (c++/53549). */
15325 {
15326 /* True iff this using-decl was written as a pack expansion
15327 (and a pack appeared in its scope or name). If a pack
15328 appeared in both, we expand the packs separately and
15329 manually merge them. */
15334 {
15337 in_decl);
15339 }
15340 else
15346 {
15350 {
15353 }
15357 }
15358 else
15366 {
15368 {
15373 }
15375 }
15383 {
15392 {
15395 }
15399 }
15403 }
15404 else
15405 {
15408 }
15413 {
15424 {
15425 /* If this is the canonical decl, we don't have to
15426 mess with instantiations, and often we can't (for
15427 typename, template type parms and such). Note that
15428 TYPE_NAME is not correct for the above test if
15429 we've copied the type for a typedef. */
15435 }
15437 /* Check to see if we already have the specialization we
15438 need. */
15444 {
15447 {
15449 complain,
15452 /* The context and type of an injected-class-name are
15453 the same, so we don't need to substitute both. */
15455 /* If CTX is unchanged, then T is in fact the
15456 specialization we want. That situation occurs when
15457 referencing a static data member within in its own
15458 class. We can use pointer equality, rather than
15459 same_type_p, because DECL_CONTEXT is always
15460 canonical... */
15462 /* ... unless T is a member template; in which
15463 case our caller can be willing to create a
15464 specialization of that template represented
15465 by T. */
15469 }
15472 {
15475 {
15482 }
15483 else
15485 }
15486 }
15487 else
15488 {
15490 /* Subsequent calls to pushdecl will fill this in. */
15492 /* A local variable. */
15494 /* Unless this is a reference to a static variable from an
15495 enclosing function, in which case we need to fill it in now. */
15497 {
15501 }
15503 }
15504 /* If we already have the specialization we need, there is
15505 nothing more to do. */
15507 {
15510 }
15512 /* Create a new node for the specialization we need. */
15514 {
15517 else
15527 /* Substituting the type might have recursively instantiated this
15528 same alias (c++/86171). */
15531 {
15534 }
15535 }
15540 {
15544 {
15545 /* It may seem that this case cannot occur, since:
15547 typedef void f();
15548 void g() { f x; }
15550 declares a function, not a variable. However:
15552 typedef void f();
15553 template <typename T> void g() { T t; }
15554 template void g<f>();
15556 is an attempt to declare a variable with function
15557 type. */
15559 /* R is not yet sufficiently initialized, so we
15560 just use its name. */
15563 }
15565 /* Wait until cp_finish_decl to set this again, to handle
15566 circular dependency (template/instantiate6.C). */
15571 {
15573 /* If the DECL_VALUE_EXPR is converted to the declared type,
15574 preserve the identity so that gimplify_type_sizes works. */
15580 {
15583 }
15592 else
15596 }
15600 }
15606 /* Clear out the mangled name and RTL for the instantiation. */
15612 /* The initializer must not be expanded until it is required;
15613 see [temp.inst]. */
15617 {
15623 /* Possibly limit visibility based on template args. */
15626 {
15630 }
15634 }
15637 {
15638 /* A static data member declaration is always marked
15639 external when it is declared in-class, even if an
15640 initializer is present. We mimic the non-template
15641 processing here. */
15650 }
15651 else
15652 {
15657 }
15666 /* Preserve a typedef that names a type. */
15668 {
15672 /* common_handle_aligned_attribute doesn't apply the alignment
15673 to DECL_ORIGINAL_TYPE. */
15677 }
15680 }
15685 }
15686 #undef RETURN
15688 out:
15689 /* Restore the file and line information. */
15693 }
15695 /* Substitute into the complete parameter type list PARMS. */
15697 tree
15699 tree args,
15700 tsubst_flags_t complain,
15701 tree in_decl)
15702 {
15704 }
15706 /* Substitute into the ARG_TYPES of a function type.
15707 If END is a TREE_CHAIN, leave it and any following types
15708 un-substituted. */
15710 static tree
15712 tree args,
15713 tree end,
15714 tsubst_flags_t complain,
15715 tree in_decl)
15716 {
15725 {
15726 /* For a pack expansion, perform substitution on the
15727 entire expression. Later on, we'll handle the arguments
15728 one-by-one. */
15733 /* So that we'll spin through the parameters, one by one. */
15735 else
15736 {
15737 /* We only partially substituted into the parameter
15738 pack. Our type is TYPE_PACK_EXPANSION. */
15741 }
15742 }
15743 else
15746 /* Check if a substituted type is erroneous before substituting into
15747 the rest of the chain. */
15749 {
15756 {
15758 {
15762 }
15764 }
15765 }
15767 /* We do not substitute into default arguments here. The standard
15768 mandates that they be instantiated only when needed, which is
15769 done in build_over_call. */
15772 /* Except that we do substitute default arguments under tsubst_lambda_expr,
15773 since the new op() won't have any associated template arguments for us
15774 to refer to later. */
15786 {
15790 /* Do array-to-pointer, function-to-pointer conversion, and ignore
15791 top-level qualifiers as required. */
15795 {
15796 /* We've instantiated a template before its default arguments
15797 have been parsed. This can happen for a nested template
15798 class, and is not an error unless we require the default
15799 argument in a call of this function. */
15800 remaining_arg_types
15803 remaining_arg_types);
15804 }
15805 else
15806 remaining_arg_types
15808 }
15811 }
15813 /* Substitute into a FUNCTION_TYPE or METHOD_TYPE. This routine does
15814 *not* handle the exception-specification for FNTYPE, because the
15815 initial substitution of explicitly provided template parameters
15816 during argument deduction forbids substitution into the
15817 exception-specification:
15819 [temp.deduct]
15821 All references in the function type of the function template to the
15822 corresponding template parameters are replaced by the specified tem-
15823 plate argument values. If a substitution in a template parameter or
15824 in the function type of the function template results in an invalid
15825 type, type deduction fails. [Note: The equivalent substitution in
15826 exception specifications is done only when the function is instanti-
15827 ated, at which point a program is ill-formed if the substitution
15828 results in an invalid type.] */
15830 static tree
15832 tree args,
15833 tsubst_flags_t complain,
15834 tree in_decl)
15835 {
15836 tree return_type;
15839 /* The TYPE_CONTEXT is not used for function/method types. */
15842 /* DR 1227: Mixing immediate and non-immediate contexts in deduction
15843 failure. */
15847 {
15848 /* Substitute the argument types. */
15860 {
15861 /* DR 1207: 'this' is in scope in the trailing return type. */
15863 }
15865 /* Substitute the return type. */
15869 {
15872 }
15873 }
15874 else
15875 /* Substitute the return type. */
15880 /* DR 486 clarifies that creation of a function type with an
15881 invalid return type is a deduction failure. */
15884 {
15886 {
15889 else
15891 }
15893 }
15896 {
15897 /* Substitute the argument types. */
15902 }
15904 /* Construct a new type node and return it. */
15907 }
15909 /* FNTYPE is a FUNCTION_TYPE or METHOD_TYPE. Substitute the template
15910 ARGS into that specification, and return the substituted
15911 specification. If there is no specification, return NULL_TREE. */
15913 static tree
15915 tree args,
15916 tsubst_flags_t complain,
15917 tree in_decl,
15919 {
15920 tree specs;
15921 tree new_specs;
15926 {
15927 /* A noexcept-specifier. */
15932 {
15933 /* Defer instantiation of noexcept-specifiers to avoid
15934 excessive instantiations (c++/49107). */
15937 {
15938 /* We already partially instantiated this member template,
15939 so combine the new args with the old. */
15944 }
15945 else
15946 {
15949 }
15950 }
15951 else
15952 {
15954 {
15956 args);
15958 }
15960 }
15962 /* We've instantiated a template before a noexcept-specifier
15963 contained therein has been parsed. This can happen for
15964 a nested template class:
15966 struct S {
15967 template<typename> struct B { B() noexcept(...); };
15968 struct A : B<int> { ... use B() ... };
15969 };
15971 where completing B<int> will trigger instantiating the
15972 noexcept, even though we only parse it at the end of S. */
15974 {
15977 }
15978 }
15980 {
15983 else
15985 {
15986 tree spec;
15991 {
15992 /* Expand the pack expansion type. */
15995 in_decl);
16001 else
16002 {
16003 /* We're substituting into a member template, so
16004 we got a TYPE_PACK_EXPANSION back. Add that
16005 expansion and move on. */
16009 expanded_specs,
16010 complain);
16013 }
16014 }
16017 {
16020 else
16025 complain);
16026 }
16029 }
16030 }
16032 }
16034 /* Substitute through a TREE_LIST of types or expressions, handling pack
16035 expansions. */
16037 tree
16039 {
16046 ;
16048 {
16052 }
16055 else
16063 ;
16065 {
16069 }
16072 else
16079 ;
16084 else
16095 /* Determine the number of arguments. */
16097 {
16100 }
16103 else
16107 {
16115 else
16117 }
16120 }
16122 /* Take the tree structure T and replace template parameters used
16123 therein with the argument vector ARGS. IN_DECL is an associated
16124 decl for diagnostics. If an error occurs, returns ERROR_MARK_NODE.
16125 Issue error and warning messages under control of COMPLAIN. Note
16126 that we must be relatively non-tolerant of extensions here, in
16127 order to preserve conformance; if we allow substitutions that
16128 should not be allowed, we may allow argument deductions that should
16129 not succeed, and therefore report ambiguous overload situations
16130 where there are none. In theory, we could allow the substitution,
16131 but indicate that it should have failed, and allow our caller to
16132 make sure that the right thing happens, but we don't try to do this
16133 yet.
16135 This function is used for dealing with types, decls and the like;
16136 for expressions, use tsubst_expr or tsubst_copy. */
16138 tree
16140 {
16175 /* Reuse typedefs. We need to do this to handle dependent attributes,
16176 such as attribute aligned. */
16179 {
16183 {
16184 /* DECL represents an alias template and we want to
16185 instantiate it. */
16189 }
16193 {
16197 }
16202 else
16203 /* The typedef is from a non-template context. */
16207 {
16209 r = cp_build_qualified_type
16213 }
16214 else
16215 {
16216 /* We don't have an instantiation yet, so drop the typedef. */
16221 }
16222 }
16239 {
16243 /* Fall through. */
16269 {
16274 /* Fix up type of the magic NOP_EXPR with TREE_SIDE_EFFECTS if
16275 needed. */
16281 /* If we're in a partial instantiation, preserve the magic NOP_EXPR
16282 with TREE_SIDE_EFFECTS that indicates this is not an integral
16283 constant expression. */
16286 {
16289 }
16292 }
16296 {
16304 else
16306 }
16307 /* Fall through. */
16311 {
16325 {
16328 /* See through ARGUMENT_PACK_SELECT arguments. */
16331 }
16336 {
16338 /* If ARG is an argument pack, we don't actually want to
16339 perform a substitution here, because substitutions
16340 for argument packs are only done
16341 element-by-element. We can get to this point when
16342 substituting the type of a non-type template
16343 parameter pack, when that type actually contains
16344 template parameter packs from an outer template, e.g.,
16346 template<typename... Types> struct A {
16347 template<Types... Values> struct B { };
16348 }; */
16352 {
16355 /* When building concept checks for the purpose of
16356 deducing placeholders, we can end up with wildcards
16357 where types are expected. Adjust this to the deduced
16358 value. */
16366 return cp_build_qualified_type
16368 }
16370 {
16371 /* We are processing a type constructed from a
16372 template template parameter. */
16383 /* Consider this code:
16385 template <template <class> class Template>
16386 struct Internal {
16387 template <class Arg> using Bind = Template<Arg>;
16388 };
16390 template <template <class> class Template, class Arg>
16391 using Instantiate = Template<Arg>; //#0
16393 template <template <class> class Template,
16394 class Argument>
16395 using Bind =
16396 Instantiate<Internal<Template>::template Bind,
16397 Argument>; //#1
16399 When #1 is parsed, the
16400 BOUND_TEMPLATE_TEMPLATE_PARM representing the
16401 parameter `Template' in #0 matches the
16402 UNBOUND_CLASS_TEMPLATE representing the argument
16403 `Internal<Template>::template Bind'; We then want
16404 to assemble the type `Bind<Argument>' that can't
16405 be fully created right now, because
16406 `Internal<Template>' not being complete, the Bind
16407 template cannot be looked up in that context. So
16408 we need to "store" `Bind<Argument>' for later
16409 when the context of Bind becomes complete. Let's
16410 store that in a TYPENAME_TYPE. */
16414 argvec),
16415 typename_type,
16416 complain);
16418 /* We can get a TEMPLATE_TEMPLATE_PARM here when we
16419 are resolving nested-types in the signature of a
16420 member function templates. Otherwise ARG is a
16421 TEMPLATE_DECL and is the real template to be
16422 instantiated. */
16430 complain);
16431 return cp_build_qualified_type
16433 }
16436 else
16437 /* TEMPLATE_PARM_INDEX. */
16439 }
16442 /* This can happen during the attempted tsubst'ing in
16443 unify. This means that we don't yet have any information
16444 about the template parameter in question. */
16447 /* Early in template argument deduction substitution, we don't
16448 want to reduce the level of 'auto', or it will be confused
16449 with a normal template parm in subsequent deduction.
16450 Similarly, don't reduce the level of template parameters to
16451 avoid mismatches when deducing their types. */
16455 /* If we get here, we must have been looking at a parm for a
16456 more deeply nested template. Make a new version of this
16457 template parameter, but with a lower level. */
16460 {
16465 {
16468 }
16474 /* Cache lowering a type parameter or a simple template
16475 template parameter. */
16479 {
16491 /* Propagate constraints on placeholders since they are
16492 only instantiated during satisfaction. */
16497 else
16499 }
16507 {
16509 /* We might need to substitute into the types of non-type
16510 template parameters. This also lowers the level of
16511 the ttp appropriately. */
16524 }
16527 /* OK, now substitute the type of the non-type parameter. We
16528 couldn't do it earlier because it might be an auto parameter,
16529 and we wouldn't need to if we had an argument. */
16538 }
16541 }
16547 /* We should never be tsubsting a binfo. */
16551 /* A vector of template arguments. */
16557 {
16561 /* [temp.deduct]
16563 Type deduction may fail for any of the following
16564 reasons:
16566 -- Attempting to create a pointer to reference type.
16567 -- Attempting to create a reference to a reference type or
16568 a reference to void.
16570 Core issue 106 says that creating a reference to a reference
16571 during instantiation is no longer a cause for failure. We
16572 only enforce this check in strict C++98 mode. */
16576 {
16579 /* We keep track of the last time we issued this error
16580 message to avoid spewing a ton of messages during a
16581 single bad template instantiation. */
16584 {
16589 else
16592 }
16595 }
16599 {
16601 {
16604 type);
16605 else
16607 type);
16608 }
16610 }
16612 {
16616 }
16618 /* In C++0x, during template argument substitution, when there is an
16619 attempt to create a reference to a reference type, reference
16620 collapsing is applied as described in [14.3.1/4 temp.arg.type]:
16622 "If a template-argument for a template-parameter T names a type
16623 that is a reference to a type A, an attempt to create the type
16624 'lvalue reference to cv T' creates the type 'lvalue reference to
16625 A,' while an attempt to create the type type rvalue reference to
16626 cv T' creates the type T"
16627 */
16628 r = cp_build_reference_type
16631 else
16636 /* Will this ever be needed for TYPE_..._TO values? */
16640 }
16642 {
16645 {
16646 /* [temp.deduct]
16648 Type deduction may fail for any of the following
16649 reasons:
16651 -- Attempting to create "pointer to member of T" when T
16652 is not a class type. */
16656 }
16658 {
16662 }
16664 {
16668 }
16671 {
16672 /* The type of the implicit object parameter gets its
16673 cv-qualifiers from the FUNCTION_TYPE. */
16674 tree memptr;
16675 tree method_type
16680 complain);
16681 }
16682 else
16685 complain);
16686 }
16689 {
16690 tree fntype;
16691 tree specs;
16696 /* Substitute the exception specification. */
16704 }
16706 {
16711 /* As an optimization, we avoid regenerating the array type if
16712 it will obviously be the same as T. */
16716 /* These checks should match the ones in create_array_type_for_decl.
16718 [temp.deduct]
16720 The deduction may fail for any of the following reasons:
16722 -- Attempting to create an array with an element type that
16723 is void, a function type, or a reference type, or [DR337]
16724 an abstract class type. */
16730 {
16734 }
16747 {
16750 }
16753 }
16756 {
16759 {
16762 in_decl);
16767 {
16772 }
16774 }
16775 else
16788 {
16792 }
16794 {
16795 /* Normally, make_typename_type does not require that the CTX
16796 have complete type in order to allow things like:
16798 template <class T> struct S { typename S<T>::X Y; };
16800 But, such constructs have already been resolved by this
16801 point, so here CTX really should have complete type, unless
16802 it's a partial instantiation. */
16805 }
16807 /* FIXME: TYPENAME_IS_CLASS_P conflates 'class' vs 'struct' vs 'union'
16808 tags. TYPENAME_TYPE should probably remember the exact tag that
16809 was written. */
16810 enum tag_types tag_type
16820 {
16823 }
16826 {
16828 {
16832 else
16834 }
16836 {
16840 else
16842 }
16843 }
16845 return cp_build_qualified_type
16847 }
16850 {
16862 }
16865 {
16866 tree type;
16880 complain);
16881 }
16884 {
16885 tree type;
16902 else
16903 {
16907 /* In a template ~id could be either a complement expression
16908 or an unqualified-id naming a destructor; if instantiating
16909 it produces an expression, it's not an id-expression or
16910 member access. */
16913 }
16918 }
16921 {
16925 else
16932 }
16952 /* We should use one of the expression tsubsts for these codes. */
16958 }
16959 }
16961 /* Convenience wrapper over tsubst for substituting into the LHS
16962 of the :: scope resolution operator. */
16964 static tree
16966 {
16969 }
16971 /* Convenience wrapper over tsubst for substituting into an id-expression
16972 without resolving its terminal name. */
16974 static tree
16976 {
16978 }
16980 /* OLDFNS is a lookup set of member functions from some class template, and
16981 NEWFNS is a lookup set of member functions from NEWTYPE, a specialization
16982 of that class template. Return the subset of NEWFNS which are
16983 specializations of a function from OLDFNS. */
16985 static tree
16987 {
16988 /* Record all member functions from the old lookup set OLDFNS into
16989 VISIBLE_SET. */
16993 {
16995 {
16996 /* Imprecisely handle dependent using-decl by keeping all members
16997 in the new lookup set that are defined in a base class, i.e.
16998 members that could plausibly have been introduced by this
16999 dependent using-decl.
17000 FIXME: Track which members are introduced by a dependent
17001 using-decl precisely, perhaps by performing another lookup
17002 from the substituted USING_DECL_SCOPE. */
17005 }
17006 else
17008 }
17010 /* Returns true iff (a less specialized version of) FN appeared in
17011 the old lookup set OLDFNS. */
17014 /* FN is a member function from a base class, introduced via a
17015 using-decl; if it might have been introduced by a dependent
17016 using-decl then just conservatively keep it, otherwise look
17017 in the old lookup set for FN exactly. */
17020 /* FN is a member function template from the current class;
17021 look in the old lookup set for the TEMPLATE_DECL from which
17022 it was specialized. */
17024 else
17025 /* FN is a non-template member function from the current class;
17026 look in the old lookup set for the FUNCTION_DECL from which
17027 it was specialized. */
17030 };
17035 {
17038 }
17042 /* Filter out from NEWFNS the member functions that weren't
17043 previously visible according to OLDFNS. */
17048 {
17050 filtered_size++;
17051 }
17057 }
17059 /* tsubst a BASELINK. OBJECT_TYPE, if non-NULL, is the type of the
17060 expression on the left-hand side of the "." or "->" operator. We
17061 only do the lookup if we had a dependent BASELINK. Otherwise we
17062 adjust it onto the instantiated heirarchy. */
17064 static tree
17067 {
17079 {
17086 }
17094 {
17099 /* See maybe_dependent_member_ref. */
17101 {
17104 template_args);
17107 }
17110 /* Treat as-if non-dependent below. */
17115 complain);
17117 {
17118 /* Filter out from the new lookup set those functions which didn't
17119 appear in the original lookup set (in a less specialized form).
17120 This is needed to preserve the consistency of member lookup
17121 performed in an incomplete-class context, within which
17122 later-declared members ought to remain invisible. */
17125 binfo_type);
17127 }
17130 {
17136 }
17139 }
17140 else
17141 {
17142 /* We're going to overwrite pieces below, make a duplicate. */
17146 {
17147 /* The decl we found was from non-dependent scope, but we still need
17148 to update the binfos for the instantiated qualifying_scope. */
17152 }
17153 }
17155 /* If lookup found a single function, mark it as used at this point.
17156 (If lookup found multiple functions the one selected later by
17157 overload resolution will be marked as used at that point.) */
17159 {
17165 /* We might have instantiated an auto function. */
17167 }
17170 {
17171 /* Add back the template arguments, if present. */
17176 /* Update the conversion operator type. */
17178 }
17184 {
17186 qualifying_scope,
17187 object_type);
17189 /* We need to call adjust_result_of_qualified_name_lookup in case the
17190 destructor names a base class, but we unset BASELINK_QUALIFIED_P
17191 so that we still get virtual function binding. */
17193 }
17196 }
17198 /* Like tsubst_expr for a SCOPE_REF, given by QUALIFIED_ID. DONE is
17199 true if the qualified-id will be a postfix-expression in-and-of
17200 itself; false if more of the postfix-expression follows the
17201 QUALIFIED_ID. ADDRESS_P is true if the qualified-id is the operand
17202 of "&". */
17204 static tree
17208 {
17209 tree expr;
17210 tree scope;
17211 tree name;
17213 tree template_args;
17218 /* Figure out what name to look up. */
17221 {
17230 }
17231 else
17232 {
17235 }
17237 /* Substitute into the qualifying scope. When there are no ARGS, we
17238 are just trying to simplify a non-dependent expression. In that
17239 case the qualifying scope may be dependent, and, in any case,
17240 substituting will not help. */
17243 {
17246 }
17247 else
17251 {
17253 /* We built one in tsubst_baselink. */
17255 else
17256 {
17259 template_args);
17261 QUALIFIED_NAME_IS_TEMPLATE
17263 }
17266 }
17269 {
17271 {
17272 /* A BIT_NOT_EXPR is used to represent a destructor. */
17274 {
17278 }
17279 else
17282 }
17283 else
17287 {
17289 {
17293 }
17295 }
17296 }
17299 {
17303 /* Remember that there was a reference to this entity. */
17306 }
17309 {
17315 }
17318 {
17319 /* We may be repeating a check already done during parsing, but
17320 if it was well-formed and passed then, it will pass again
17321 now, and if it didn't, we wouldn't have got here. The case
17322 we want to catch is when we couldn't tell then, and can now,
17323 namely when templ prior to substitution was an
17324 identifier. */
17330 complain);
17331 else
17333 }
17339 {
17340 expr = (adjust_result_of_qualified_name_lookup
17342 expr = (finish_qualified_id_expr
17346 }
17348 /* Expressions do not generally have reference type. */
17350 /* However, if we're about to form a pointer-to-member, we just
17351 want the referenced member referenced. */
17361 }
17363 /* tsubst the initializer for a VAR_DECL. INIT is the unsubstituted
17364 initializer, DECL is the substituted VAR_DECL. Other arguments are as
17365 for tsubst. */
17367 static tree
17370 {
17379 {
17381 {
17383 {
17388 }
17389 }
17391 {
17392 /* If we had an initializer but it
17393 instantiated to nothing,
17394 value-initialize the object. This will
17395 only occur when the initializer was a
17396 pack expansion where the parameter packs
17397 used in that expansion were of length
17398 zero. */
17404 }
17405 }
17408 }
17410 /* If T is a reference to a dependent member of the current instantiation C and
17411 we are trying to refer to that member in a partial instantiation of C,
17412 return a SCOPE_REF; otherwise, return NULL_TREE.
17414 This can happen when forming a C++17 deduction guide, as in PR96199. */
17416 static tree
17418 tree in_decl)
17419 {
17436 {
17445 complain);
17446 }
17451 {
17457 }
17460 {
17463 /* The TYPE_DECL for a typename has DECL_CONTEXT of the typename
17464 scope, but it doesn't need to be rewritten again. */
17468 }
17472 else
17475 }
17477 /* Helper function for tsubst_omp_clauses, used for instantiation of
17478 OMP_CLAUSE_DECL of clauses. */
17480 static tree
17483 {
17487 /* Handle OpenMP iterators. */
17491 {
17492 tree ret;
17495 else
17496 {
17500 {
17514 }
17518 }
17522 }
17524 /* Handle an OpenMP array section represented as a TREE_LIST (or
17525 OMP_CLAUSE_DOACROSS_KIND). An OMP_CLAUSE_DOACROSS (with a depend
17526 kind of OMP_CLAUSE_DOACROSS_SINK) can also be represented as a
17527 TREE_LIST. We can handle it exactly the same as an array section
17528 (purpose, value, and a chain), even though the nomenclature
17529 (low_bound, length, etc) is different. */
17531 {
17532 tree low_bound
17545 }
17547 {
17548 tree low_bound
17551 in_decl);
17559 length);
17560 }
17562 /* Undo convert_from_reference tsubst_expr could have called. */
17568 }
17570 /* Like tsubst_copy, but specifically for OpenMP clauses. */
17572 static tree
17575 {
17581 {
17587 {
17590 {
17596 }
17597 /* FALLTHRU */
17627 /* FALLTHRU */
17661 {
17664 {
17671 }
17672 else
17674 }
17701 {
17704 }
17709 else
17740 }
17743 {
17760 /* tsubst_expr on SCOPE_REF results in returning
17761 finish_non_static_data_member result. Undo that here. */
17765 {
17770 {
17774 CASE_CONVERT:
17783 /* FALLTHRU */
17787 }
17788 }
17794 {
17797 {
17800 }
17801 }
17805 }
17806 }
17810 {
17815 {
17818 }
17819 }
17821 }
17823 /* Like tsubst_expr, but unshare TREE_LIST nodes. */
17825 static tree
17827 tree in_decl)
17828 {
17829 #define RECUR(t) tsubst_copy_asm_operands (t, args, complain, in_decl)
17847 {
17850 else
17851 {
17855 }
17856 }
17861 #undef RECUR
17862 }
17864 /* Used to temporarily communicate the list of #pragma omp parallel
17865 clauses to #pragma omp for instantiation if they are combined
17866 together. */
17871 cp_decomp *);
17873 /* Substitute one OMP_FOR iterator. */
17875 static bool
17879 {
17880 #define RECUR(NODE) \
17881 tsubst_stmt ((NODE), args, complain, in_decl)
17893 {
17896 {
17901 {
17910 else
17912 {
17914 {
17920 }
17923 }
17924 }
17925 }
17929 }
17931 {
17932 /* We need to jump through some hoops to handle declarations in the
17933 init-statement, since we might need to handle auto deduction,
17934 but we need to keep control of initialization. */
17938 }
17939 else
17940 {
17942 {
17945 {
17949 {
17953 CASE_CONVERT:
17961 {
17964 }
17965 /* FALLTHRU */
17969 }
17970 }
17971 }
17972 else
17974 }
17976 {
17982 }
17983 else
17987 {
17993 NULL_TREE);
17994 else
17996 }
17999 {
18007 {
18012 }
18015 }
18025 {
18027 {
18028 /* Declare the variable, but don't let that initialize it. */
18033 }
18036 {
18040 {
18049 }
18050 else
18054 {
18059 }
18060 else
18064 }
18070 }
18073 {
18074 /* Declare and initialize the variable. */
18077 }
18079 {
18084 {
18086 {
18092 {
18095 /* Move lastprivate (decl) clause to OMP_FOR_CLAUSES. */
18100 }
18103 {
18105 decl);
18107 }
18110 {
18112 decl);
18114 }
18115 else
18117 }
18120 }
18122 {
18125 ? OMP_CLAUSE_LASTPRIVATE
18130 {
18133 }
18134 }
18135 }
18138 {
18142 }
18143 else
18147 {
18158 {
18166 }
18167 else
18173 {
18179 }
18183 {
18191 }
18192 else
18198 }
18207 #undef RECUR
18208 }
18210 /* Helper function of tsubst_expr, find OMP_TEAMS inside
18211 of OMP_TARGET's body. */
18213 static tree
18215 {
18218 {
18227 }
18229 }
18231 /* Helper function for tsubst_expr. For decomposition declaration
18232 artificial base DECL, which is tsubsted PATTERN_DECL, tsubst
18233 also the corresponding decls representing the identifiers
18234 of the decomposition declaration. Return DECL if successful
18235 or error_mark_node otherwise, set *FIRST to the first decl
18236 in the list chained through DECL_CHAIN and *CNT to the number
18237 of such decls. */
18239 static tree
18242 {
18247 decl2
18252 {
18254 {
18257 }
18269 else
18270 {
18274 }
18281 {
18284 }
18285 else
18287 }
18290 }
18292 /* Return the proper local_specialization for init-capture pack DECL. */
18294 static tree
18296 {
18297 /* We handle normal pack captures by forwarding to the specialization of the
18298 captured parameter. We can't do that for pack init-captures; we need them
18299 to have their own local_specialization. We created the individual
18300 VAR_DECLs (if any) under build_capture_proxy, and we need to collect them
18301 when we process the DECL_EXPR for the pack init-capture in the template.
18302 So, how do we find them? We don't know the capture proxy pack when
18303 building the individual resulting proxies, and we don't know the
18304 individual proxies when instantiating the pack. What we have in common is
18305 the FIELD_DECL.
18307 So...when we instantiate the FIELD_DECL, we stick the result in
18308 local_specializations. Then at the DECL_EXPR we look up that result, see
18309 how many elements it has, synthesize the names, and look them up. */
18323 {
18328 }
18330 {
18335 else
18337 }
18339 }
18341 /* T is an operand of a template tree being substituted. Return whether
18342 T is dependent such that we should suppress some warnings that would
18343 make sense if the substituted expression were written directly, like
18344 template <int I> bool f() { return I == 2; }
18345 We don't want to warn when instantiating f that comparing two constants
18346 always has the same value.
18348 This is a more limited concept of dependence than instantiation-dependent;
18349 here we don't care whether substitution could fail. */
18351 static bool
18353 {
18362 }
18364 /* A superset of tsubst_expr that also handles statement trees. */
18366 static tree
18368 {
18369 #define RETURN(EXP) do { r = (EXP); goto out; } while(0)
18370 #define RECUR(NODE) \
18371 tsubst_stmt ((NODE), args, complain, in_decl)
18374 tree r;
18375 location_t loc;
18387 {
18389 {
18393 }
18412 else
18425 {
18430 }
18434 {
18436 tree init;
18442 {
18445 {
18449 {
18454 }
18456 }
18457 else
18458 {
18459 /* This is a non-dependent using-decl, and we'll have
18460 used the names it found during template parsing. We do
18461 not want to do the lookup again, because we might not
18462 find the things we found then. */
18465 /* We still need to push the bindings so that we can look up
18466 this name later. */
18469 }
18470 }
18473 {
18474 /* We're in tsubst_lambda_expr, we've already inserted a new
18475 capture proxy, so look it up and register it. */
18476 tree inst;
18478 {
18482 }
18484 {
18485 inst = (retrieve_local_specialization
18489 }
18490 else
18495 }
18502 /* Don't copy the old closure; we'll create a new one in
18503 tsubst_lambda_expr. */
18505 else
18506 {
18510 {
18511 /* By marking the declaration as instantiated, we avoid
18512 trying to instantiate it. Since instantiate_decl can't
18513 handle local variables, and since we've already done
18514 all that needs to be done, that's the right thing to
18515 do. */
18520 /* Anonymous aggregates are a special case. */
18523 {
18526 {
18530 }
18532 }
18537 {
18545 }
18546 else
18547 {
18562 {
18566 }
18571 const_init = (DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P
18574 /* In a non-template function, VLA type declarations are
18575 handled in grokdeclarator; for templates, handle them
18576 now. */
18580 {
18584 asmspec_tree
18588 }
18591 decomp);
18595 }
18596 }
18597 }
18600 }
18610 {
18614 }
18619 {
18620 /* Construct another range_for, if this is not a final
18621 substitution (for inside a generic lambda of a
18622 template). Otherwise convert to a regular for. */
18624 stmt = (processing_template_decl
18635 {
18639 }
18643 unroll
18645 unroll);
18647 {
18654 }
18655 else
18664 }
18671 {
18675 }
18681 {
18685 }
18697 {
18703 }
18706 {
18707 /* We're partially instantiating a generic lambda, but the condition
18708 of the constexpr if is still dependent. Don't substitute into the
18709 branches now, just remember the template arguments. */
18717 }
18721 {
18726 }
18727 else
18728 {
18736 }
18742 {
18752 }
18760 else
18768 else
18789 {
18795 {
18800 }
18801 }
18805 {
18807 tree label;
18814 }
18820 /* Computed goto's must be tsubst'd into. On the other hand,
18821 non-computed gotos must not be; the identifier in question
18822 will have no binding. */
18824 else
18830 {
18847 }
18852 {
18857 }
18858 else
18859 {
18864 else
18871 else
18877 else
18879 }
18883 {
18887 {
18889 /* Prevent instantiate_decl from trying to instantiate
18890 this variable. We've already done all that needs to be
18891 done. */
18894 }
18899 }
18905 /* This is a partial instantiation, try again when full. */
18908 {
18909 /* Local classes are not independent templates; they are
18910 instantiated along with their containing function. And this
18911 way we don't have to deal with pushing out of one local class
18912 to instantiate a member of another local class. */
18913 /* Closures are handled by the LAMBDA_EXPR. */
18929 }
18933 {
18950 }
18979 {
18986 }
19002 {
19016 in_decl);
19018 {
19025 }
19036 any_range_for
19043 {
19052 }
19053 else
19058 else
19065 else
19066 {
19074 }
19077 t));
19079 }
19085 /* FALLTHRU */
19095 in_decl);
19097 {
19102 }
19103 else
19104 {
19108 }
19113 {
19115 "%<#pragma omp critical%> with %<hint%> clause requires "
19118 }
19129 {
19132 {
19137 }
19138 else
19139 {
19143 }
19145 }
19146 else
19148 OMP_CLAUSE_DEPEND_INVALID,
19157 ? C_ORT_ACC
19176 {
19179 /* For combined target teams, ensure the num_teams and
19180 thread_limit clause expressions are evaluated on the host,
19181 before entering the target construct. */
19190 {
19193 tf_none);
19200 OMP_CLAUSE_FIRSTPRIVATE);
19204 }
19205 }
19242 {
19246 }
19247 else
19259 /* FALLTHRU */
19277 {
19283 {
19286 }
19288 {
19292 {
19295 }
19300 }
19301 else
19302 {
19305 }
19310 }
19311 else
19312 {
19319 {
19322 }
19325 {
19330 {
19333 }
19335 {
19339 {
19342 }
19347 }
19348 else
19349 {
19352 }
19356 }
19357 else
19358 {
19362 }
19366 }
19370 {
19376 {
19380 {
19385 }
19389 }
19390 else
19391 {
19396 }
19397 }
19401 {
19405 }
19418 /* If the first operand was a statement, we're done with it. */
19423 complain));
19432 }
19435 out:
19438 #undef RECUR
19439 #undef RETURN
19440 }
19442 /* Instantiate the special body of the artificial DECL_OMP_DECLARE_REDUCTION
19443 function. For description of the body see comment above
19444 cp_parser_omp_declare_reduction_exprs. */
19446 static void
19448 {
19454 tree_stmt_iterator tsi;
19465 {
19472 /* tsubsting a local var_decl leaves DECL_CONTEXT null, as we
19473 expect to be pushing it. */
19485 }
19487 {
19507 }
19508 }
19510 /* T is a postfix-expression that is not being used in a function
19511 call. Return the substituted version of T. */
19513 static tree
19515 tsubst_flags_t complain,
19516 tree in_decl)
19517 {
19521 else
19525 }
19527 /* Subroutine of tsubst_lambda_expr: add the FIELD/INIT capture pair to the
19528 LAMBDA_EXPR_CAPTURE_LIST passed in LIST. Do deduction for a previously
19529 dependent init-capture. EXPLICIT_P is true if the original list had
19530 explicit captures. */
19532 static void
19534 tsubst_flags_t complain)
19535 {
19537 {
19540 {
19544 }
19551 }
19554 }
19556 /* T is a LAMBDA_EXPR. Generate a new LAMBDA_EXPR for the current
19557 instantiation context. Instantiating a pack expansion containing a lambda
19558 might result in multiple lambdas all based on the same lambda in the
19559 template. */
19561 tree
19563 {
19577 else
19588 {
19593 else
19605 {
19606 /* For a VLA, simply tsubsting the field type won't work, we need to
19607 go through add_capture again. XXX do we want to do this for all
19608 captures? */
19609 tree name = (get_identifier
19618 }
19625 {
19626 /* Remember these for when we've pushed local_specializations. */
19629 }
19635 {
19644 complain);
19645 }
19646 else
19647 {
19653 }
19654 }
19663 /* If we're pushed into another scope (PR105652), fix it. */
19668 /* Do this again now that LAMBDA_EXPR_EXTRA_SCOPE is set. */
19685 {
19688 }
19691 {
19694 }
19698 else
19699 {
19700 /* The body of a lambda-expression is not a subexpression of the
19701 enclosing expression. Parms are to have DECL_CHAIN tsubsted,
19702 which would be skipped if cp_unevaluated_operand. */
19703 cp_evaluated ev;
19705 /* Fix the type of 'this'.
19706 For static and xobj member functions we use this to transport the
19707 lambda's closure type. It appears that in the regular case the
19708 object parameter is still pulled off, and then re-added again anyway.
19709 So perhaps we could do something better here? */
19713 tree inst = (oldtmpl
19718 {
19721 }
19727 /* Let finish_function set this. */
19733 else
19734 /* Still increment function_depth so that we don't GC in the
19735 middle of an expression. */
19745 /* Now record them for lookup_init_capture_pack. */
19748 {
19752 }
19758 {
19759 /* We might not partially instantiate some parts of the function, so
19760 copy these flags from the original template. */
19766 }
19768 /* [temp.deduct] A lambda-expression appearing in a function type or a
19769 template parameter is not considered part of the immediate context for
19770 the purposes of template argument deduction. */
19775 /* We already have a body block from start_lambda_function, we don't
19776 need another to confuse NRV (91217). */
19787 else
19790 /* The capture list was built up in reverse order; fix that now. */
19797 }
19799 out:
19805 }
19807 /* Subroutine of maybe_fold_fn_template_args. */
19809 static bool
19811 {
19814 {
19820 {
19823 }
19828 {
19832 }
19833 }
19836 }
19838 /* Try to do constant evaluation of any explicit template arguments in FN
19839 before overload resolution, to get any errors only once. Return true iff
19840 we didn't have any problems folding. */
19842 static bool
19844 {
19862 }
19864 /* Helper function for tsubst_expr CALL_EXPR and ARRAY_REF handling. */
19866 static void
19869 {
19872 {
19877 else
19878 {
19879 /* Expand the pack expansion and push each entry onto CALL_ARGS. */
19882 {
19887 {
19892 }
19893 }
19894 else
19895 /* A partial substitution. Add one entry. */
19897 }
19898 }
19899 }
19901 /* Like tsubst but deals with expressions and performs semantic
19902 analysis. */
19904 tree
19906 {
19907 #define RETURN(EXP) do { retval = (EXP); goto out; } while(0)
19908 #define RECUR(NODE) \
19909 tsubst_expr (NODE, args, complain, in_decl)
19912 location_t save_loc;
19921 /* N3276 decltype magic only applies to calls at the top level or on the
19922 right side of a comma. */
19926 /* This flag only applies to id-expressions at the top level, and
19927 controls resolution thereof. */
19936 {
19939 /* Fall through. */
19941 {
19942 tree decl;
19943 cp_id_kind idk;
19947 {
19950 }
19955 /* Look up the name. */
19958 /* By convention, expressions use ERROR_MARK_NODE to indicate
19959 failure, not NULL_TREE. */
19973 input_location);
19977 {
19981 }
19983 }
19986 {
19987 tree object;
19993 else
20002 {
20007 }
20010 {
20017 /* If we built a function concept check, return the underlying
20018 template-id. So we can evaluate it as a function call. */
20023 }
20026 {
20031 complain);
20035 }
20038 {
20041 }
20042 else
20054 {
20055 /* C++20 P0846: we can encounter an IDENTIFIER_NODE here when
20056 name lookup found nothing when parsing the template name. */
20059 }
20060 else
20062 }
20065 {
20069 {
20070 /* A type conversion to reference type will be enclosed in
20071 such an indirect ref, but the substitution of the cast
20072 will have also added such an indirect ref. */
20074 }
20075 else
20084 }
20087 {
20091 }
20094 {
20098 {
20103 }
20105 {
20110 }
20117 flags));
20118 }
20121 {
20127 }
20134 {
20135 tree type;
20149 {
20169 }
20172 }
20175 {
20179 }
20191 {
20194 }
20196 {
20200 }
20201 /* Fall through. */
20216 {
20223 }
20226 /* convert_like should have created an IMPLICIT_CONV_EXPR. */
20237 else
20239 in_decl);
20274 {
20275 /* If either OP0 or OP1 was value- or type-dependent, suppress
20276 warnings that depend on the range of the types involved. */
20290 tree r = build_x_binary_op
20292 op0,
20294 ? ERROR_MARK
20296 op1,
20298 ? ERROR_MARK
20307 }
20310 {
20318 }
20322 {
20327 }
20328 else
20342 {
20344 releasing_vec index_exp_list;
20347 tree r;
20353 else
20358 }
20364 {
20370 {
20374 }
20376 {
20380 }
20382 }
20387 {
20396 /* We only want to compute the number of arguments. */
20399 else
20406 {
20408 /* Set TREE_USED for the benefit of -Wunused. */
20412 }
20420 {
20423 else
20431 else
20436 }
20437 else
20439 }
20440 /* Fall through */
20443 {
20444 tree r;
20452 {
20453 /* When there are no ARGS, we are trying to evaluate a
20454 non-dependent expression from the parser. Trying to do
20455 the substitutions may not work. */
20458 }
20459 else
20460 {
20465 else
20469 }
20474 else
20479 {
20481 {
20483 {
20487 }
20488 else
20492 }
20494 }
20496 }
20499 {
20507 }
20521 {
20526 tree r = build_x_modify_expr
20530 /* TREE_NO_WARNING must be set if either the expression was
20531 parenthesized or it uses an operator such as >>= rather
20532 than plain assignment. In the former case, it was already
20533 set and must be copied. In the latter case,
20534 build_x_modify_expr sets it and it must not be reset
20535 here. */
20540 }
20545 /* Remember that there was a reference to this entity. */
20552 {
20557 tree ret;
20564 else
20565 {
20569 }
20571 /* If there was an initializer in the original tree, but it
20572 instantiated to an empty list, then we should pass a
20573 non-NULL empty vector to tell build_new that it was an
20574 empty initializer() rather than no initializer. This can
20575 only happen when the initializer is a pack expansion whose
20576 parameter packs are of length zero. */
20581 else
20582 {
20586 else
20587 {
20590 }
20591 }
20593 /* Avoid passing an enclosing decl to valid_array_size_p. */
20600 complain);
20608 }
20611 {
20617 complain));
20618 }
20621 {
20625 op0,
20629 }
20632 {
20633 tree function;
20637 tree ret;
20640 /* Internal function with no arguments. */
20644 /* When we parsed the expression, we determined whether or
20645 not Koenig lookup should be performed. */
20648 {
20651 }
20653 {
20658 }
20662 {
20664 in_decl);
20666 {
20673 }
20674 else
20677 }
20682 {
20683 /* Do nothing; calling tsubst_expr on an identifier
20684 would incorrectly perform unqualified lookup again.
20686 Note that we can also have an IDENTIFIER_NODE if the earlier
20687 unqualified lookup found a dependent local extern declaration
20688 (as per finish_call_expr); in that case koenig_p will be false
20689 and we do want to do the lookup again to find the substituted
20690 declaration. */
20695 }
20696 else
20697 {
20699 {
20705 }
20706 else
20711 /* Avoid error about taking the address of a constructor. */
20716 /* When KOENIG_P, we don't want to mark_used the callee before
20717 augmenting the overload set via ADL, so during this initial
20718 substitution we disable mark_used by setting tf_conv (68942). */
20724 }
20727 releasing_vec call_args;
20730 /* Stripped-down processing for a call in a thunk. Specifically, in
20731 the thunk template for a generic lambda. */
20733 {
20734 /* Now that we've expanded any packs, the number of call args
20735 might be different. */
20739 {
20746 }
20747 /* We aren't going to do normal overload resolution, so force the
20748 template-id to resolve. */
20751 {
20752 /* In a thunk, pass through args directly, without any
20753 conversions. */
20758 }
20760 {
20761 /* If there are no other args, just push 'this'. */
20764 else
20765 {
20766 /* Otherwise, shift the other args over to make room. */
20772 }
20773 }
20776 /* The thunk location is not interesting. */
20783 }
20785 /* We do not perform argument-dependent lookup if normal
20786 lookup finds a non-function, in accordance with the
20787 resolution of DR 218. */
20790 /* If lookup found a member function, the Koenig lookup is
20791 not appropriate, even if an unqualified-name was used
20792 to denote the function. */
20795 /* C++20 P0846: Lookup found nothing. */
20798 /* Only do this when substitution turns a dependent call
20799 into a non-dependent call. */
20811 {
20816 {
20817 /* For backwards compatibility and good diagnostics, try
20818 the unqualified lookup again if we aren't in SFINAE
20819 context. */
20825 {
20828 "and no declarations were found by "
20829 "argument-dependent lookup at the point "
20834 /* In a lambda fn, we have to be careful to not
20835 introduce new this captures. Legacy code can't
20836 be using lambdas anyway, so it's ok to be
20837 stricter. Be strict with C++20 template-id ADL too.
20838 And be strict if we're already failing anyway. */
20844 else
20848 {
20859 {
20862 "declarations in dependent base %qT are "
20868 else
20872 }
20873 else
20875 "%qD declared here, later in the "
20879 }
20882 }
20883 }
20885 {
20889 }
20890 }
20892 /* Remember that there was a reference to this entity. */
20901 /* Put back tf_decltype for the actual call. */
20906 {
20910 {
20912 "wrong number of arguments to "
20915 }
20916 else
20924 {
20926 "wrong number of arguments to "
20930 }
20934 complain);
20940 {
20942 complain);
20946 }
20951 {
20953 "wrong number of arguments to "
20956 }
20957 else
20958 {
20963 {
20966 }
20969 }
20973 /* Unsupported internal function with arguments. */
20975 }
20980 complain);
20982 {
20983 /* FUNCTION is a template-id referring to a concept definition. */
20988 /* Calls to standard and variable concepts should have been
20989 previously diagnosed. */
20992 /* Ensure the result is wrapped as a call expression. */
20994 }
20995 else
20998 koenig_p,
20999 complain);
21002 {
21008 {
21012 }
21014 /* This also suppresses -Wredundant-move. */
21016 }
21019 }
21022 {
21029 {
21031 {
21036 }
21037 else
21038 {
21043 }
21045 }
21046 else
21047 {
21050 }
21055 }
21058 {
21063 input_location));
21064 }
21070 {
21071 tree object;
21072 tree object_type;
21073 tree member;
21074 tree r;
21078 /* Remember that there was a reference to this entity. */
21089 else
21096 {
21099 }
21101 {
21103 complain);
21107 }
21111 {
21113 {
21118 {
21121 }
21123 {
21128 }
21129 }
21130 }
21133 {
21134 /* Lookup the template functions now that we know what the
21135 scope is. */
21142 {
21145 args);
21146 member = (adjust_result_of_qualified_name_lookup
21148 object_type));
21149 }
21150 else
21151 {
21153 input_location);
21155 }
21156 }
21160 {
21162 {
21166 else
21169 }
21171 }
21175 complain);
21179 }
21186 {
21193 tree r;
21202 /* We do not want to process the index of aggregate
21203 initializers as they are identifier nodes which will be
21204 looked up by digest_init. */
21208 {
21211 }
21216 {
21218 /* An identifier index is looked up in the type
21219 being initialized, not the current scope. */
21224 {
21225 /* Substitute into the pack expansion. */
21227 in_decl);
21231 ;
21233 /* Just move the argument into place. */
21235 else
21236 {
21237 /* Update the length of the final CONSTRUCTOR
21238 arguments vector, and note that we will need to
21239 copy.*/
21242 }
21243 }
21244 else
21246 }
21249 {
21254 {
21256 {
21261 }
21262 else
21264 }
21265 }
21273 {
21278 }
21282 }
21285 {
21288 {
21291 }
21292 else
21293 {
21296 }
21297 }
21304 tree r;
21309 {
21310 /* Local specialization will usually have been created when
21311 we instantiated the DECL_EXPR_DECL. */
21314 {
21315 /* We're in a generic lambda referencing a local extern
21316 from an outer block-scope of a non-template. */
21319 }
21320 }
21325 {
21327 {
21328 /* We get here for a use of 'this' in an NSDMI. */
21332 /* This can happen for a parameter name used later in a function
21333 declaration (such as in a late-specified return type). Just
21334 make a dummy decl, since it's only used for its type. */
21337 /* Give it the template pattern as its context; its true context
21338 hasn't been instantiated yet and this is good enough for
21339 mangling. */
21341 }
21343 {
21344 /* First try name lookup to find the instantiation. */
21347 {
21349 {
21350 /* During error-recovery we may find a non-variable,
21351 even an OVERLOAD: just bail out and avoid ICEs and
21352 duplicate diagnostics (c++/62207). */
21355 }
21357 {
21358 /* Make sure the one we found is the one we want. */
21362 }
21363 }
21367 else
21368 {
21369 /* This can happen for a variable used in a
21370 late-specified return type of a local lambda, or for a
21371 local static or constant. Building a new VAR_DECL
21372 should be OK in all those cases. */
21375 /* Avoid infinite recursion (79640). */
21378 {
21379 /* We can't call cp_finish_decl, so handle the
21380 initializer by hand. */
21395 }
21397 || processing_contract_condition
21404 }
21405 /* Remember this for subsequent uses. */
21408 }
21411 }
21412 else
21419 {
21420 /* ??? We're doing a subset of finish_id_expression here. */
21422 /* Replace an evaluated use of the thread_local variable with
21423 a call to its wrapper. */
21429 /* If the original type was a reference, we'll be wrapped in
21430 the appropriate INDIRECT_REF. */
21432 }
21436 {
21437 tree enum_type;
21438 tree v;
21445 /* Unfortunately, we cannot just call lookup_name here.
21446 Consider:
21448 template <int I> int f() {
21449 enum E { a = I };
21450 struct S { void g() { E e = a; } };
21451 };
21453 When we instantiate f<7>::S::g(), say, lookup_name is not
21454 clever enough to find f<7>::a. */
21455 enum_type
21465 /* We didn't find the name. That should never happen; if
21466 name-lookup found it during preliminary parsing, we
21467 should find it again here during instantiation. */
21470 }
21474 {
21475 tree ctx;
21480 {
21483 {
21487 }
21489 }
21490 }
21505 {
21506 /* Template template argument like the following example need
21507 special treatment:
21509 template <template <class> class TT> struct C {};
21510 template <class T> struct D {
21511 template <class U> struct E {};
21512 C<E> c; // #1
21513 };
21514 D<int> d; // #2
21516 We are processing the template argument `E' in #1 for
21517 the template instantiation #2. Originally, `E' is a
21518 TEMPLATE_DECL with `D<T>' as its DECL_CONTEXT. Now we
21519 have to substitute this with one having context `D<int>'. */
21524 }
21525 else
21526 /* Ordinary template template argument. */
21534 /* We shouldn't have built any of these during initial template
21535 generation. Instead, they should be built during instantiation
21536 in response to the saved STMT_IS_FULL_EXPR_P setting. */
21540 {
21550 }
21568 {
21569 /* Instantiate any typedefs in the type. */
21574 }
21577 {
21581 {
21584 }
21586 }
21589 /* These can sometimes show up in a partial instantiation, but never
21590 involve template parms. */
21606 /* ??? There's no point in copying it for now, but maybe some
21607 day it will contain more information, such as a pointer back
21608 to the containing function, inlined copy or so. */
21620 {
21624 }
21627 {
21628 tree object_ptr
21633 }
21640 {
21644 else
21650 }
21653 {
21662 /* If the resulting list of expression statement is empty,
21663 fold it further into void_node. */
21668 }
21671 {
21673 {
21674 /* We don't have a full set of template arguments yet; don't touch
21675 the lambda at all. */
21678 }
21682 }
21691 else
21692 /* Recreate the PAREN_EXPR from __builtin_assoc_barrier. */
21693 {
21697 }
21700 {
21705 complain));
21706 }
21709 {
21713 }
21716 /* No need to substitute further, a RANGE_EXPR will always be built
21717 with constant operands. */
21722 {
21726 /* We need to do this here as well as in tsubst_copy so we get the
21727 other tsubst_copy_and_build semantics for a PARM_DECL operand. */
21732 /* force_paren_expr can also create a VIEW_CONVERT_EXPR. */
21735 /* Otherwise, we're dealing with a wrapper to make a C++20 template
21736 parameter object const. */
21739 {
21740 /* The template argument is not const, presumably because
21741 it is still dependent, and so not the const template parm
21742 object. */
21746 {
21747 /* Don't add a wrapper to these. */
21750 }
21751 else
21752 /* Do add a wrapper otherwise (in particular, if op is
21753 another TEMPLATE_PARM_INDEX). */
21755 }
21757 }
21760 {
21767 op3);
21770 }
21773 /* Handle Objective-C++ constructs, if appropriate. */
21777 /* We shouldn't get here, but keep going if !flag_checking. */
21781 }
21783 #undef RECUR
21784 #undef RETURN
21785 out:
21788 }
21790 /* Verify that the instantiated ARGS are valid. For type arguments,
21791 make sure that the type's linkage is ok. For non-type arguments,
21792 make sure they are constants if they are integral or enumerations.
21793 Emit an error under control of COMPLAIN, and return TRUE on error. */
21795 static bool
21797 {
21801 {
21811 }
21813 {
21814 /* [basic.link]: A name with no linkage (notably, the name
21815 of a class or enumeration declared in a local scope)
21816 shall not be used to declare an entity with linkage.
21817 This implies that names with no linkage cannot be used as
21818 template arguments
21820 DR 757 relaxes this restriction for C++0x. */
21825 {
21826 /* DR 488 makes use of a type with no linkage cause
21827 type deduction to fail. */
21829 {
21832 else
21835 }
21837 }
21838 /* In order to avoid all sorts of complications, we do not
21839 allow variably-modified types as template arguments. */
21841 {
21845 }
21846 }
21847 /* Class template and alias template arguments should be OK. */
21849 ;
21850 /* A non-type argument of integral or enumerated type must be a
21851 constant. */
21856 {
21860 }
21862 }
21864 static bool
21866 {
21871 {
21874 }
21878 }
21880 /* Call mark_used on each entity within the non-type template arguments in
21881 ARGS for an instantiation of TMPL, to ensure that each such entity is
21882 considered odr-used (and therefore marked for instantiation) regardless of
21883 whether the specialization was first formed in a template context (which
21884 inhibits mark_used).
21886 This function assumes push_to_top_level has been called beforehand. */
21888 static void
21890 {
21891 /* It suffices to do this only when instantiating a primary template. */
21895 /* We already marked outer arguments when specializing the context. */
21899 {
21900 /* A (pointer/reference to) function or variable NTTP argument. */
21903 {
21909 {
21910 /* Pass tf_none to avoid duplicate diagnostics: if this call
21911 fails then an earlier call to mark_used for this argument
21912 must have also failed and emitted a diagnostic. */
21915 }
21916 }
21917 /* A class NTTP argument. */
21920 {
21923 {
21926 }
21928 };
21931 }
21932 }
21933 }
21935 /* We're out of SFINAE context now, so generate diagnostics for the access
21936 errors we saw earlier when instantiating D from TMPL and ARGS. */
21938 static void
21940 {
21952 }
21954 /* Instantiate the indicated variable, function, or alias template TMPL with
21955 the template arguments in TARG_PTR. */
21957 tree
21959 {
21963 tree fndecl;
21964 tree gen_tmpl;
21970 /* The other flags are not relevant anymore here, especially tf_partial
21971 shouldn't be set. For instance, we may be called while doing a partial
21972 substitution of a template variable, but the type of the variable
21973 template may be auto, in which case we will call do_auto_deduction
21974 in mark_used (which clears tf_partial) and the auto must be properly
21975 reduced at that time for the deduction to work. */
21983 /* If this function is a clone, handle it specially. */
21985 {
21986 tree spec;
21987 tree clone;
21989 /* Use DECL_ABSTRACT_ORIGIN because only FUNCTION_DECLs have
21990 DECL_CLONED_FUNCTION. */
21996 /* Look for the clone. */
22000 /* We should always have found the clone by now. */
22003 }
22008 /* Check to see if we already have this specialization. */
22012 /* targ_ptr only has the innermost template args, so add the outer ones
22013 from tmpl, which could be either a partial instantiation or gen_tmpl (in
22014 the case of a non-dependent call within a template definition). */
22015 targ_ptr = (add_outermost_template_args
22017 targ_ptr));
22023 || ((fndecl
22029 {
22031 {
22035 }
22037 }
22040 complain))
22043 /* We are building a FUNCTION_DECL, during which the access of its
22044 parameters and return types have to be checked. However this
22045 FUNCTION_DECL which is the desired context for access checking
22046 is not built yet. We solve this chicken-and-egg problem by
22047 deferring all checks until we have the FUNCTION_DECL. */
22050 /* Instantiation of the function happens in the context of the function
22051 template, not the context of the overload resolution we're doing. */
22053 /* If there are dependent arguments, e.g. because we're doing partial
22054 ordering, make sure processing_template_decl stays set. */
22058 {
22059 tree ctx;
22061 /* If the context of the partially instantiated template is
22062 already non-dependent, then we might as well use it. */
22064 else
22068 }
22075 {
22076 /* We need to determine if we're using a partial or explicit
22077 specialization now, because the type of the variable could be
22078 different. */
22084 {
22090 }
22091 }
22093 /* Substitute template parameters to obtain the specialization. */
22101 {
22104 }
22106 /* The DECL_TI_TEMPLATE should always be the immediate parent
22107 template, not the most general template. */
22111 {
22112 /* Now that we we've formed this variable template specialization,
22113 remember the result of most_specialized_partial_spec for it. */
22116 /* And remember if the variable was declared with []. */
22120 }
22128 /* Now we know the specialization, compute access previously
22129 deferred. Do no access control for inheriting constructors,
22130 as we already checked access for the inherited constructor. */
22133 {
22138 }
22141 /* If we've just instantiated the main entry point for a function,
22142 instantiate all the alternate entry points as well. We do this
22143 by cloning the instantiation of the main entry point, not by
22144 instantiating the template clones. */
22150 {
22152 {
22153 /* Remember to reinstantiate when we're out of SFINAE so the user
22154 can see the errors. */
22156 }
22158 }
22161 }
22163 /* Instantiate the alias template TMPL with ARGS. Also push a template
22164 instantiation level, which instantiate_template doesn't do because
22165 functions and variables have sufficient context established by the
22166 callers. */
22168 static tree
22170 {
22179 /* FIXME check for satisfaction in check_instantiated_args. */
22181 {
22183 {
22184 auto_diagnostic_group d;
22187 }
22189 }
22197 {
22198 /* An alias template specialization can be dependent
22199 even if its underlying type is not. */
22202 /* Sometimes a dependent alias spec is equivalent to its expansion,
22203 sometimes not. So always use structural_comptypes. */
22205 }
22208 }
22210 /* PARM is a template parameter pack for FN. Returns true iff
22211 PARM is used in a deducible way in the argument list of FN. */
22213 static bool
22215 {
22218 {
22220 tree packs;
22226 {
22227 /* The template parameter pack is used in a function parameter
22228 pack. If this is the end of the parameter list, the
22229 template parameter pack is deducible. */
22232 else
22233 /* Otherwise, not. Well, it could be deduced from
22234 a non-pack parameter, but doing so would end up with
22235 a deduction mismatch, so don't bother. */
22237 }
22238 }
22239 /* The template parameter pack isn't used in any function parameter
22240 packs, but it might be used deeper, e.g. tuple<Args...>. */
22242 }
22244 /* Subroutine of fn_type_unification: check non-dependent parms for
22245 convertibility. */
22247 static int
22252 {
22253 /* Non-constructor methods need to leave a conversion for 'this', which
22254 isn't included in nargs here. */
22260 {
22266 /* For a function parameter pack that occurs at the end of the
22267 parameter-declaration-list, the type A of each remaining
22268 argument of the call is compared with the type P of the
22269 declarator-id of the function parameter pack. */
22275 /* For a function parameter pack that does not occur at the
22276 end of the parameter-declaration-list, the type of the
22277 parameter pack is a non-deduced context. */
22281 {
22289 }
22292 }
22295 }
22297 /* The FN is a TEMPLATE_DECL for a function. ARGS is an array with
22298 NARGS elements of the arguments that are being used when calling
22299 it. TARGS is a vector into which the deduced template arguments
22300 are placed.
22302 Returns either a FUNCTION_DECL for the matching specialization of FN or
22303 NULL_TREE if no suitable specialization can be found. If EXPLAIN_P is
22304 true, diagnostics will be printed to explain why it failed.
22306 If FN is a conversion operator, or we are trying to produce a specific
22307 specialization, RETURN_TYPE is the return type desired.
22309 The EXPLICIT_TARGS are explicit template arguments provided via a
22310 template-id.
22312 The parameter STRICT is one of:
22314 DEDUCE_CALL:
22315 We are deducing arguments for a function call, as in
22316 [temp.deduct.call]. If RETURN_TYPE is non-null, we are
22317 deducing arguments for a call to the result of a conversion
22318 function template, as in [over.call.object].
22320 DEDUCE_CONV:
22321 We are deducing arguments for a conversion function, as in
22322 [temp.deduct.conv].
22324 DEDUCE_EXACT:
22325 We are deducing arguments when doing an explicit instantiation
22326 as in [temp.explicit], when determining an explicit specialization
22327 as in [temp.expl.spec], or when taking the address of a function
22328 template, as in [temp.deduct.funcaddr]. */
22330 tree
22332 tree explicit_targs,
22333 tree targs,
22336 tree return_type,
22337 unification_kind_t strict,
22342 {
22343 tree parms;
22344 tree fntype;
22349 /* type_unification_real will pass back any access checks from default
22350 template argument substitution. */
22352 /* We don't have all the template args yet. */
22365 full_targs = (add_outermost_template_args
22367 targs));
22372 /* In C++0x, it's possible to have a function template whose type depends
22373 on itself recursively. This is most obvious with decltype, but can also
22374 occur with enumeration scope (c++/48969). So we need to catch infinite
22375 recursion and reject the substitution at deduction time; this function
22376 will return error_mark_node for any repeated substitution.
22378 This also catches excessive recursion such as when f<N> depends on
22379 f<N-1> across all integers, and returns error_mark_node for all the
22380 substitutions back up to the initial one.
22382 This is, of course, not reentrant. */
22391 {
22392 /* [temp.deduct]
22394 The specified template arguments must match the template
22395 parameters in kind (i.e., type, nontype, template), and there
22396 must not be more arguments than there are parameters;
22397 otherwise type deduction fails.
22399 Nontype arguments must match the types of the corresponding
22400 nontype template parameters, or must be convertible to the
22401 types of the corresponding nontype parameters as specified in
22402 _temp.arg.nontype_, otherwise type deduction fails.
22404 All references in the function type of the function template
22405 to the corresponding template parameters are replaced by the
22406 specified template argument values. If a substitution in a
22407 template parameter or in the function type of the function
22408 template results in an invalid type, type deduction fails. */
22419 explicit_targs);
22421 /* Adjust any explicit template arguments before entering the
22422 substitution context. */
22423 explicit_targs
22430 /* Substitute the explicit args into the function type. This is
22431 necessary so that, for instance, explicitly declared function
22432 arguments can match null pointed constants. If we were given
22433 an incomplete set of explicit args, we must not do semantic
22434 processing during substitution as we could create partial
22435 instantiations. */
22437 {
22442 /* Dig out the actual parm. */
22445 {
22448 }
22450 {
22453 }
22456 /* No explicit argument for this template parameter. */
22459 {
22460 /* Mark the argument pack as "incomplete". We could
22461 still deduce more arguments during unification.
22462 We remove this mark in type_unification_real. */
22467 /* We have some incomplete argument packs. */
22469 }
22470 }
22473 {
22475 {
22478 }
22481 /* Ignore any access checks; we'll see them again in
22482 instantiate_template and they might have the wrong
22483 access path at this point. */
22494 }
22496 /* Place the explicitly specified arguments in TARGS. */
22502 SET_NON_DEFAULT_TEMPLATE_ARGS_COUNT
22504 }
22507 {
22513 }
22518 /* Never do unification on the 'this' parameter. */
22522 {
22523 /* We're deducing for a call to the result of a template conversion
22524 function. The parms we really want are in return_type. */
22528 }
22530 {
22532 }
22534 /* We allow incomplete unification without an error message here
22535 because the standard doesn't seem to explicitly prohibit it. Our
22536 callers must be ready to deal with unification failures in any
22537 event. */
22539 /* If we aren't explaining yet, push tinst context so we can see where
22540 any errors (e.g. from class instantiations triggered by instantiation
22541 of default template arguments) come from. If we are explaining, this
22542 context is redundant. */
22544 {
22547 }
22557 /* Now that we have bindings for all of the template arguments,
22558 ensure that the arguments deduced for the template template
22559 parameters have compatible template parameter lists. We cannot
22560 check this property before we have deduced all template
22561 arguments, because the template parameter types of a template
22562 template parameter might depend on prior template parameters
22563 deduced after the template template parameter. The following
22564 ill-formed example illustrates this issue:
22566 template<typename T, template<T> class C> void f(C<5>, T);
22568 template<int N> struct X {};
22570 void g() {
22571 f(X<5>(), 5l); // error: template argument deduction fails
22572 }
22574 The template parameter list of 'C' depends on the template type
22575 parameter 'T', but 'C' is deduced to 'X' before 'T' is deduced to
22576 'long'. Thus, we can't check that 'C' cannot bind to 'X' at the
22577 time that we deduce 'C'. */
22580 {
22583 }
22585 deduced:
22587 /* As a refinement of CWG2369, check first and foremost non-dependent
22588 conversions that we know are not going to induce template instantiation
22589 (PR99599). */
22591 && incomplete
22597 /* CWG2369: Check satisfaction before non-deducible conversions. */
22599 {
22603 }
22605 /* DR 1391: All parameters have args, now check non-dependent parms for
22606 convertibility. We don't do this if all args were explicitly specified,
22607 as the standard says that we substitute explicit args immediately. */
22614 /* All is well so far. Now, check:
22616 [temp.deduct]
22618 When all template arguments have been deduced, all uses of
22619 template parameters in nondeduced contexts are replaced with
22620 the corresponding deduced argument values. If the
22621 substitution results in an invalid type, as described above,
22622 type deduction fails. */
22624 {
22627 }
22629 /* Also collect access checks from the instantiation. */
22642 /* Now perform any access checks encountered during substitution. */
22649 /* If we're looking for an exact match, check that what we got
22650 is indeed an exact match. It might not be if some template
22651 parameters are used in non-deduced contexts. But don't check
22652 for an exact match if we have dependent template arguments;
22653 in that case we're doing partial ordering, and we already know
22654 that we have two candidates that will provide the actual type. */
22656 {
22660 tree sarg
22666 {
22670 }
22672 /* add_candidates uses DEDUCE_EXACT for x.operator foo(), but args
22673 doesn't contain the trailing void, and conv fns are always (). */
22675 {
22679 }
22680 }
22682 /* After doing deduction with the inherited constructor, actually return an
22683 instantiation of the inheriting constructor. */
22689 fail:
22692 {
22694 /* Reset once we're all the way out. */
22696 }
22699 }
22701 /* Returns true iff PARM is a forwarding reference in the context of
22702 template argument deduction for TMPL. */
22704 static bool
22706 {
22707 /* [temp.deduct.call], "A forwarding reference is an rvalue reference to a
22708 cv-unqualified template parameter ..." */
22713 {
22715 /* [temp.deduct.call], "... that does not represent a template parameter
22716 of a class template (during class template argument deduction)." */
22720 {
22721 /* Since the template parameters of a synthesized guide consist of
22722 the template parameters of the class template followed by those of
22723 the constructor (if any), we can tell if PARM represents a template
22724 parameter of the class template by comparing its index with the
22725 arity of the class template. */
22730 }
22732 }
22734 }
22736 /* Adjust types before performing type deduction, as described in
22737 [temp.deduct.call] and [temp.deduct.conv]. The rules in these two
22738 sections are symmetric. PARM is the type of a function parameter
22739 or the return type of the conversion function. ARG is the type of
22740 the argument passed to the call, or the type of the value
22741 initialized with the result of the conversion function.
22742 ARG_EXPR is the original argument expression, which may be null. */
22744 static int
22746 unification_kind_t strict,
22749 tree arg_expr)
22750 {
22754 {
22759 /* [temp.deduct.conv] First remove a reference type on parm.
22760 DRs 322 & 976 affected this. */
22764 /* Swap PARM and ARG throughout the remainder of this
22765 function; the handling is precisely symmetric since PARM
22766 will initialize ARG rather than vice versa. */
22772 /* Core issue #873: Do the DR606 thing (see below) for these cases,
22773 too, but here handle it by stripping the reference from PARM
22774 rather than by adding it to ARG. */
22779 /* Nothing else to do in this case. */
22784 }
22787 {
22788 /* [temp.deduct.call]
22790 If P is not a reference type:
22792 --If A is an array type, the pointer type produced by the
22793 array-to-pointer standard conversion (_conv.array_) is
22794 used in place of A for type deduction; otherwise,
22796 --If A is a function type, the pointer type produced by
22797 the function-to-pointer standard conversion
22798 (_conv.func_) is used in place of A for type deduction;
22799 otherwise,
22801 --If A is a cv-qualified type, the top level
22802 cv-qualifiers of A's type are ignored for type
22803 deduction. */
22808 else
22810 }
22812 /* [temp.deduct.call], "If P is a forwarding reference and the argument is
22813 an lvalue, the type 'lvalue reference to A' is used in place of A for
22814 type deduction." */
22817 /* try_one_overload doesn't provide an arg_expr, but
22818 functions are always lvalues. */
22822 /* [temp.deduct.call]
22824 If P is a cv-qualified type, the top level cv-qualifiers
22825 of P's type are ignored for type deduction. If P is a
22826 reference type, the type referred to by P is used for
22827 type deduction. */
22830 {
22833 }
22836 }
22838 /* Return true if computing a conversion from FROM to TO might induce template
22839 instantiation. Conversely, if this predicate returns false then computing
22840 the conversion definitely won't induce template instantiation. */
22842 static bool
22844 {
22851 {
22855 }
22857 /* If one of the types is a not-yet-instantiated class template
22858 specialization, then computing the conversion might instantiate
22859 it in order to inspect bases, conversion functions and/or
22860 converting constructors. */
22869 /* Converting from one pointer type to another, or between
22870 reference-related types, always yields a standard conversion. */
22874 /* Converting to a non-aggregate class type will consider its
22875 user-declared constructors, which might induce instantiation. */
22880 /* Similarly, converting from a class type will consider its conversion
22881 functions. */
22886 /* Otherwise, computing this conversion definitely won't induce
22887 template instantiation. */
22889 }
22891 /* Subroutine of fn_type_unification. PARM is a function parameter of a
22892 template which doesn't contain any deducible template parameters; check if
22893 ARG is a suitable match for it. STRICT, FLAGS and EXPLAIN_P are as in
22894 unify_one_argument. */
22896 static int
22900 {
22901 tree type;
22905 else
22913 {
22916 }
22918 {
22920 {
22921 /* This conversion was already computed earlier (when
22922 computing only non-instantiating conversions). */
22925 }
22934 /* Avoid recalculating this in add_function_candidate. */
22935 ok = (*conv_p
22937 else
22941 }
22945 else
22947 }
22951 /* Returns true iff the expression EXPR is one from which a template
22952 argument can be deduced. In other words, if it's an undecorated
22953 use of a template non-type parameter. */
22955 static bool
22957 {
22958 /* Strip implicit conversions and implicit INDIRECT_REFs. */
22964 }
22966 /* Returns true iff the array domain DOMAIN uses a template parameter in a
22967 deducible way; that is, if it has a max value of <PARM> - 1. */
22969 static bool
22971 {
22980 }
22982 /* Returns true iff the template arguments ARGS use a template parameter
22983 in a deducible way. */
22985 static bool
22987 {
22989 {
22993 else
22994 {
23001 else
23003 }
23006 }
23008 }
23010 /* Returns true iff TYPE contains any deducible references to template
23011 parameters, as per 14.8.2.5. */
23013 static bool
23015 {
23019 /* T
23020 cv-list T
23021 TT<T>
23022 TT<i>
23023 TT<> */
23028 /* T*
23029 T&
23030 T&& */
23034 /* T[integer-constant ]
23035 type [i] */
23040 /* T type ::*
23041 type T::*
23042 T T::*
23043 T (type ::*)()
23044 type (T::*)()
23045 type (type ::*)(T)
23046 type (T::*)(T)
23047 T (type ::*)(T)
23048 T (T::*)()
23049 T (T::*)(T) */
23052 || (uses_deducible_template_parms
23055 /* template-name <T> (where template-name refers to a class template)
23056 template-name <i> (where template-name refers to a class template) */
23063 /* type (T)
23064 T()
23065 T(T) */
23067 {
23081 }
23084 }
23086 /* Subroutine of type_unification_real and unify_pack_expansion to
23087 handle unification of a single P/A pair. Parameters are as
23088 for those functions. */
23090 static int
23094 {
23101 /* We can't deduce anything from this, but we might get all the
23102 template args from other function args. */
23105 /* Implicit conversions (Clause 4) will be performed on a function
23106 argument to convert it to the type of the corresponding function
23107 parameter if the parameter type contains no template-parameters that
23108 participate in template argument deduction. */
23111 /* For function parameters with no deducible template parameters,
23112 just return. We'll check non-dependent conversions later. */
23116 {
23118 arg_strict = (UNIFY_ALLOW_OUTER_LEVEL
23119 | UNIFY_ALLOW_MORE_CV_QUAL
23133 }
23135 /* We only do these transformations if this is the top-level
23136 parameter_type_list in a call or declaration matching; in other
23137 situations (nested function declarators, template argument lists) we
23138 won't be comparing a type to an expression, and we don't do any type
23139 adjustments. */
23141 {
23143 {
23146 {
23147 /* [temp.deduct.type] A template-argument can be
23148 deduced from a pointer to function or pointer
23149 to member function argument if the set of
23150 overloaded functions does not contain function
23151 templates and at most one of a set of
23152 overloaded functions provides a unique
23153 match. */
23157 /* If a unique match was not found, this is a
23158 non-deduced context, so we still succeed. */
23160 }
23166 }
23170 }
23171 else
23176 /* For deduction from an init-list we need the actual list. */
23180 }
23182 /* for_each_template_parm callback that always returns 0. */
23184 static int
23186 {
23188 }
23190 /* for_each_template_parm any_fn callback to handle deduction of a template
23191 type argument from the type of an array bound. */
23193 static int
23195 {
23203 {
23209 }
23211 /* Keep walking. */
23213 }
23215 /* Try to deduce any not-yet-deduced template type arguments from the type of
23216 an array bound. This is handled separately from unify because 14.8.2.5 says
23217 "The type of a type parameter is only deduced from an array bound if it is
23218 not otherwise deduced." */
23220 static void
23222 {
23227 }
23229 /* Most parms like fn_type_unification.
23231 If SUBR is 1, we're being called recursively (to unify the
23232 arguments of a function or method parameter of a function
23233 template).
23235 CHECKS is a pointer to a vector of access checks encountered while
23236 substituting default template arguments. */
23238 static int
23240 tree full_targs,
23241 tree xparms,
23245 unification_kind_t strict,
23248 {
23253 tree parms;
23264 /* Reset the number of non-defaulted template arguments contained
23265 in TARGS. */
23268 again:
23273 /* Only fn_type_unification cares about terminal void. */
23280 {
23285 /* For a function parameter pack that occurs at the end of the
23286 parameter-declaration-list, the type A of each remaining
23287 argument of the call is compared with the type P of the
23288 declarator-id of the function parameter pack. */
23294 /* For a function parameter pack that does not occur at the
23295 end of the parameter-declaration-list, the type of the
23296 parameter pack is a non-deduced context. */
23303 explain_p))
23305 }
23310 {
23311 /* Unify the remaining arguments with the pack expansion type. */
23312 tree argvec;
23315 /* Allocate a TREE_VEC and copy in all of the arguments */
23320 /* Copy the parameter into parmvec. */
23326 /* Advance to the end of the list of parameters. */
23328 }
23330 /* Fail if we've reached the end of the parm list, and more args
23331 are present, and the parm list isn't variadic. */
23334 /* Fail if parms are left and they don't have default values and
23335 they aren't all deduced as empty packs (c++/57397). This is
23336 consistent with sufficient_parms_p. */
23339 {
23343 do
23344 {
23347 count++;
23349 }
23353 type_pack_p);
23354 }
23357 {
23358 tsubst_flags_t complain = (explain_p
23359 ? tf_warning_or_error
23364 {
23368 /* Clear the "incomplete" flags on all argument packs now so that
23369 substituting them into later default arguments works. */
23371 {
23374 }
23382 {
23387 }
23389 /* If this is an undeduced nontype parameter that depends on
23390 a type parameter, try another pass; its type may have been
23391 deduced from a later argument than the one from which
23392 this parameter can be deduced. */
23397 {
23400 }
23402 /* Core issue #226 (C++0x) [temp.deduct]:
23404 If a template argument has not been deduced, its
23405 default template argument, if any, is used.
23407 When we are in C++98 mode, TREE_PURPOSE will either
23408 be NULL_TREE or ERROR_MARK_NODE, so we do not need
23409 to explicitly check cxx_dialect here. */
23411 /* OK, there is a default argument. Wait until after the
23412 conversion check to do substitution. */
23415 /* If the type parameter is a parameter pack, then it will
23416 be deduced to an empty parameter pack. */
23418 {
23419 tree arg;
23422 {
23425 }
23426 else
23433 }
23436 }
23438 /* During partial ordering, we deduce dependent template args. */
23441 /* Now substitute into the default template arguments. */
23443 {
23448 {
23452 }
23467 {
23468 /* The type of this non-type parameter depends on undeduced
23469 parameters. Don't try to use its default argument yet,
23470 since we might deduce an argument for it on the next pass,
23471 but do check whether the arguments we already have cause
23472 substitution failure, so that that happens before we try
23473 later default arguments (78489). */
23476 NULL_TREE);
23480 else
23482 }
23483 else
23484 {
23485 /* Even if the call is happening in template context, getting
23486 here means it's non-dependent, and a default argument is
23487 considered a separate definition under [temp.decls], so we can
23488 do this substitution without processing_template_decl. This
23489 is important if the default argument contains something that
23490 might be instantiation-dependent like access (87480). */
23494 {
23495 /* First instatiate in template context, in case we still
23496 depend on undeduced template parameters. */
23499 NULL_TREE);
23503 /* We replaced all the tparms, substitute again out of
23504 template context. */
23506 }
23509 NULL_TREE);
23518 }
23527 {
23529 /* The position of the first default template argument,
23530 is also the number of non-defaulted arguments in TARGS.
23531 Record that. */
23534 }
23535 }
23539 }
23545 }
23547 /* Subroutine of type_unification_real. Args are like the variables
23548 at the call site. ARG is an overloaded function (or template-id);
23549 we try deducing template args from each of the overloads, and if
23550 only one succeeds, we go with that. Modifies TARGS and returns
23551 true on success. */
23553 static bool
23555 tree targs,
23556 tree parm,
23557 tree arg,
23558 unification_kind_t strict,
23561 {
23568 {
23571 }
23572 else
23576 /* Handle `&x' where `x' is some static or non-static member
23577 function name. */
23583 /* Strip baselink information. */
23588 {
23589 /* If we got some explicit template args, we need to plug them into
23590 the affected templates before we try to unify, in case the
23591 explicit args will completely resolve the templates in question. */
23598 {
23609 {
23614 {
23615 /* Instantiate the function to deduce its return type. */
23619 }
23628 {
23631 }
23632 }
23635 }
23636 /* If no templates (or more than one) are fully resolved by the
23637 explicit arguments, this template-id is a non-deduced context; it
23638 could still be OK if we deduce all template arguments for the
23639 enclosing call through other arguments. */
23642 }
23644 /* If ARG is, for example, "(0, &f)" then its type will be unknown
23645 -- but the deduction does not succeed because the expression is
23646 not just the function on its own. */
23648 else
23650 {
23655 {
23658 }
23659 }
23661 /* [temp.deduct.type] A template-argument can be deduced from a pointer
23662 to function or pointer to member function argument if the set of
23663 overloaded functions does not contain function templates and at most
23664 one of a set of overloaded functions provides a unique match.
23666 So if we found multiple possibilities, we return success but don't
23667 deduce anything. */
23670 {
23674 {
23679 /* Don't forget explicit template arguments in a pack. */
23683 }
23684 }
23689 }
23691 /* Core DR 115: In contexts where deduction is done and fails, or in
23692 contexts where deduction is not done, if a template argument list is
23693 specified and it, along with any default template arguments, identifies
23694 a single function template specialization, then the template-id is an
23695 lvalue for the function template specialization. */
23697 tree
23699 {
23712 {
23715 }
23717 {
23720 }
23722 {
23725 }
23728 {
23732 /* If we got some explicit template args, we need to plug them into
23733 the affected templates before we try to unify, in case the
23734 explicit args will completely resolve the templates in question. */
23742 {
23753 {
23756 {
23759 }
23762 {
23765 }
23766 }
23767 }
23769 {
23777 {
23778 tree base
23781 }
23785 }
23787 /* There were no good options and at least one bad one, so let the
23788 user know what the problem is. */
23790 }
23792 }
23794 /* As above, but error out if the expression remains overloaded. */
23796 tree
23798 {
23801 {
23805 }
23807 }
23809 /* Subroutine of resolve_overloaded_unification; does deduction for a single
23810 overload. Fills TARGS with any deduced arguments, or error_mark_node if
23811 different overloads deduce different arguments for a given parm.
23812 ADDR_P is true if the expression for which deduction is being
23813 performed was of the form "& fn" rather than simply "fn".
23815 Returns 1 on success. */
23817 static int
23819 tree orig_targs,
23820 tree targs,
23821 tree parm,
23822 tree arg,
23823 unification_kind_t strict,
23827 {
23829 tree tempargs;
23835 /* [temp.deduct.type] A template-argument can be deduced from a pointer
23836 to function or pointer to member function argument if the set of
23837 overloaded functions does not contain function templates and at most
23838 one of a set of overloaded functions provides a unique match.
23840 So if this is a template, just return success. */
23853 /* We don't copy orig_targs for this because if we have already deduced
23854 some template args from previous args, unify would complain when we
23855 try to deduce a template parameter for the same argument, even though
23856 there isn't really a conflict. */
23863 /* First make sure we didn't deduce anything that conflicts with
23864 explicitly specified args. */
23866 {
23873 /* Since we're unifying against ourselves, we will fill in
23874 template args used in the function parm list with our own
23875 template parms. Discard them. */
23878 {
23879 /* Check that the argument at each index of the deduced argument pack
23880 is equivalent to the corresponding explicitly specified argument.
23881 We may have deduced more arguments than were explicitly specified,
23882 and that's OK. */
23884 /* We used to assert ARGUMENT_PACK_INCOMPLETE_P (oldelt) here, but
23885 that's wrong if we deduce the same argument pack from multiple
23886 function arguments: it's only incomplete the first time. */
23899 }
23902 }
23905 {
23910 }
23913 }
23915 /* PARM is a template class (perhaps with unbound template
23916 parameters). ARG is a fully instantiated type. If ARG can be
23917 bound to PARM, return ARG, otherwise return NULL_TREE. TPARMS and
23918 TARGS are as for unify. */
23920 static tree
23923 {
23931 /* We need to make a new template argument vector for the call to
23932 unify. If we used TARGS, we'd clutter it up with the result of
23933 the attempted unification, even if this class didn't work out.
23934 We also don't want to commit ourselves to all the unifications
23935 we've already done, since unification is supposed to be done on
23936 an argument-by-argument basis. In other words, consider the
23937 following pathological case:
23939 template <int I, int J, int K>
23940 struct S {};
23942 template <int I, int J>
23943 struct S<I, J, 2> : public S<I, I, I>, S<J, J, J> {};
23945 template <int I, int J, int K>
23946 void f(S<I, J, K>, S<I, I, I>);
23948 void g() {
23949 S<0, 0, 0> s0;
23950 S<0, 1, 2> s2;
23952 f(s0, s2);
23953 }
23955 Now, by the time we consider the unification involving `s2', we
23956 already know that we must have `f<0, 0, 0>'. But, even though
23957 `S<0, 1, 2>' is derived from `S<0, 0, 0>', the code is invalid
23958 because there are two ways to unify base classes of S<0, 1, 2>
23959 with S<I, I, I>. If we kept the already deduced knowledge, we
23960 would reject the possibility I=1. */
23968 else
23975 }
23977 /* Given a template type PARM and a class type ARG, find the unique
23978 base type in ARG that is an instance of PARM. We do not examine
23979 ARG itself; only its base-classes. If there is not exactly one
23980 appropriate base class, return NULL_TREE. PARM may be the type of
23981 a partial specialization, as well as a plain template type. Used
23982 by unify. */
23984 static enum template_base_result
23987 {
23989 tree binfo;
23995 {
23996 /* The type could not be completed. */
23999 }
24001 /* Walk in inheritance graph order. The search order is not
24002 important, and this avoids multiple walks of virtual bases. */
24004 {
24009 {
24010 /* If there is more than one satisfactory baseclass, then:
24012 [temp.deduct.call]
24014 If they yield more than one possible deduced A, the type
24015 deduction fails.
24017 applies. */
24019 {
24020 /* [temp.deduct.call]/4.3: If there is a class C that is a
24021 (direct or indirect) base class of D and derived (directly or
24022 indirectly) from a class B and that would be a valid deduced
24023 A, the deduced A cannot be B or pointer to B, respectively. */
24025 /* Ignore r. */
24029 else
24030 {
24033 }
24034 }
24037 }
24038 }
24042 }
24044 /* Returns the level of DECL, which declares a template parameter. */
24046 static int
24048 {
24050 {
24060 }
24062 }
24064 /* Decide whether ARG can be unified with PARM, considering only the
24065 cv-qualifiers of each type, given STRICT as documented for unify.
24066 Returns nonzero iff the unification is OK on that basis. */
24068 static int
24070 {
24076 {
24077 /* Although a CVR qualifier is ignored when being applied to a
24078 substituted template parameter ([8.3.2]/1 for example), that
24079 does not allow us to unify "const T" with "int&" because both
24080 types are not of the form "cv-list T" [14.8.2.5 temp.deduct.type].
24081 It is ok when we're allowing additional CV qualifiers
24082 at the outer level [14.8.2.1]/3,1st bullet. */
24091 }
24102 }
24104 /* Determines the LEVEL and INDEX for the template parameter PARM. */
24105 void
24107 {
24111 {
24114 }
24115 else
24116 {
24119 }
24120 }
24122 #define RECUR_AND_CHECK_FAILURE(TP, TA, P, A, S, EP) \
24123 do { \
24124 if (unify (TP, TA, P, A, S, EP)) \
24125 return 1; \
24126 } while (0)
24128 /* Unifies the remaining arguments in PACKED_ARGS with the pack
24129 expansion at the end of PACKED_PARMS. Returns 0 if the type
24130 deduction succeeds, 1 otherwise. STRICT is the same as in
24131 fn_type_unification. CALL_ARGS_P is true iff PACKED_ARGS is actually a
24132 function call argument list. We'll need to adjust the arguments to make them
24133 types. SUBR tells us if this is from a recursive call to
24134 type_unification_real, or for comparing two template argument
24135 lists. */
24137 static int
24141 {
24142 tree parm
24148 /* Add in any args remembered from an earlier partial instantiation. */
24156 /* Determine the parameter packs we will be deducing from the
24157 pattern, and record their current deductions. */
24160 {
24164 /* Only template parameter packs can be deduced, not e.g. function
24165 parameter packs or __bases or __integer_pack. */
24169 /* Determine the index and level of this parameter pack. */
24174 /* Keep track of the parameter packs and their corresponding
24175 argument packs. */
24178 }
24180 /* Loop through all of the arguments that have not yet been
24181 unified and unify each with the pattern. */
24183 {
24184 tree parm;
24188 /* For each parameter pack, set its TMPL_ARG to either NULL_TREE
24189 or the element of its argument pack at the current index if
24190 this argument was explicitly specified. */
24192 {
24201 {
24204 }
24206 }
24208 /* If we had explicit template arguments, substitute them into the
24209 pattern before deduction. */
24211 {
24212 /* Some arguments might still be unspecified or dependent. */
24220 NULL_TREE);
24225 }
24226 else
24229 /* Unify the pattern with the current argument. */
24231 explain_p))
24234 /* For each parameter pack, collect the deduced value. */
24236 {
24242 }
24243 }
24245 /* Verify that the results of unification with the parameter packs
24246 produce results consistent with what we've seen before, and make
24247 the deduced argument packs available. */
24249 {
24256 /* By default keep the original deduced argument pack.
24257 If necessary, more specific code is going to update the
24258 resulting deduced argument later down in this function. */
24262 /* If NEW_ARGS contains any NULL_TREE entries, we didn't
24263 actually deduce anything. */
24271 {
24272 /* If we had fewer function args than explicit template args,
24273 just use the explicits. */
24278 }
24281 {
24282 tree result;
24283 /* Build the deduced *_ARGUMENT_PACK. */
24285 {
24288 }
24289 else
24294 /* Note the deduced argument packs for this parameter
24295 pack. */
24297 }
24301 {
24302 /* We only had the explicitly-provided arguments before, but
24303 now we have a complete set of arguments. */
24309 }
24310 else
24311 {
24315 /* During template argument deduction for the aggregate deduction
24316 candidate, the number of elements in a trailing parameter pack
24317 is only deduced from the number of remaining function
24318 arguments if it is not otherwise deduced. */
24321 /* FIXME This isn't set properly for partial instantiations. */
24327 /* Inconsistent unification of this parameter pack. */
24329 bad_old_arg,
24330 bad_new_arg);
24331 }
24332 }
24335 }
24337 /* Handle unification of the domain of an array. PARM_DOM and ARG_DOM are
24338 INTEGER_TYPEs representing the TYPE_DOMAIN of ARRAY_TYPEs. The other
24339 parameters and return value are as for unify. */
24341 static int
24345 {
24346 tree parm_max;
24347 tree arg_max;
24351 /* Our representation of array types uses "N - 1" as the
24352 TYPE_MAX_VALUE for an array with "N" elements, if "N" is
24353 not an integer constant. We cannot unify arbitrarily
24354 complex expressions, so we eliminate the MINUS_EXPRs
24355 here. */
24359 {
24362 }
24366 {
24367 /* The ARG_MAX may not be a simple MINUS_EXPR, if we are
24368 trying to unify the type of a variable with the type
24369 of a template parameter. For example:
24371 template <unsigned int N>
24372 void f (char (&) [N]);
24373 int g();
24374 void h(int i) {
24375 char a[g(i)];
24376 f(a);
24377 }
24379 Here, the type of the ARG will be "int [g(i)]", and
24380 may be a SAVE_EXPR, etc. */
24384 }
24386 /* If only one of the bounds used a MINUS_EXPR, compensate
24387 by adding one to the other bound. */
24390 integer_type_node,
24391 parm_max,
24392 integer_one_node);
24395 integer_type_node,
24396 arg_max,
24397 integer_one_node);
24401 }
24403 /* Returns whether T, a P or A in unify, is a type, template or expression. */
24407 static pa_kind_t
24409 {
24418 else
24420 }
24422 /* Deduce the value of template parameters. TPARMS is the (innermost)
24423 set of template parameters to a template. TARGS is the bindings
24424 for those template parameters, as determined thus far; TARGS may
24425 include template arguments for outer levels of template parameters
24426 as well. PARM is a parameter to a template function, or a
24427 subcomponent of that parameter; ARG is the corresponding argument.
24428 This function attempts to match PARM with ARG in a manner
24429 consistent with the existing assignments in TARGS. If more values
24430 are deduced, then TARGS is updated.
24432 Returns 0 if the type deduction succeeds, 1 otherwise. The
24433 parameter STRICT is a bitwise or of the following flags:
24435 UNIFY_ALLOW_NONE:
24436 Require an exact match between PARM and ARG.
24437 UNIFY_ALLOW_MORE_CV_QUAL:
24438 Allow the deduced ARG to be more cv-qualified (by qualification
24439 conversion) than ARG.
24440 UNIFY_ALLOW_LESS_CV_QUAL:
24441 Allow the deduced ARG to be less cv-qualified than ARG.
24442 UNIFY_ALLOW_DERIVED:
24443 Allow the deduced ARG to be a template base class of ARG,
24444 or a pointer to a template base class of the type pointed to by
24445 ARG.
24446 UNIFY_ALLOW_INTEGER:
24447 Allow any integral type to be deduced. See the TEMPLATE_PARM_INDEX
24448 case for more information.
24449 UNIFY_ALLOW_OUTER_LEVEL:
24450 This is the outermost level of a deduction. Used to determine validity
24451 of qualification conversions. A valid qualification conversion must
24452 have const qualified pointers leading up to the inner type which
24453 requires additional CV quals, except at the outer level, where const
24454 is not required [conv.qual]. It would be normal to set this flag in
24455 addition to setting UNIFY_ALLOW_MORE_CV_QUAL.
24456 UNIFY_ALLOW_OUTER_MORE_CV_QUAL:
24457 This is the outermost level of a deduction, and PARM can be more CV
24458 qualified at this point.
24459 UNIFY_ALLOW_OUTER_LESS_CV_QUAL:
24460 This is the outermost level of a deduction, and PARM can be less CV
24461 qualified at this point. */
24463 static int
24466 {
24468 tree targ;
24469 tree tparm;
24471 tsubst_flags_t complain = (explain_p
24472 ? tf_warning_or_error
24475 /* I don't think this will do the right thing with respect to types.
24476 But the only case I've seen it in so far has been array bounds, where
24477 signedness is the only information lost, and I think that will be
24478 okay. VIEW_CONVERT_EXPR can appear with class NTTP, thanks to
24479 finish_id_expression_1, and are also OK. */
24487 /* We can't deduce anything from this, but we might get all the
24488 template args from other function args. */
24494 /* If PARM uses template parameters, then we can't bail out here,
24495 even if ARG == PARM, since we won't record unifications for the
24496 template parameters. We might need them if we're trying to
24497 figure out which of two things is more specialized. */
24502 /* Handle init lists early, so the rest of the function can assume
24503 we're dealing with a type. */
24505 {
24506 tree elttype;
24511 /* We can only deduce from an initializer list argument if the
24512 parameter is std::initializer_list or an array; otherwise this
24513 is a non-deduced context. */
24518 else
24519 {
24521 /* Deduction is defined in terms of a single type, so just punt
24522 on the (bizarre) std::initializer_list<T...>. */
24525 }
24530 /* If ELTTYPE has no deducible template parms, skip deduction from
24532 else
24534 {
24542 {
24546 /* It should only be possible to get here for a call. */
24548 elt_strict |= maybe_adjust_types_for_deduction
24551 }
24554 explain_p);
24555 }
24559 {
24560 /* Also deduce from the length of the initializer list. */
24567 }
24569 /* If the std::initializer_list<T> deduction worked, replace the
24570 deduced A with std::initializer_list<A>. */
24572 {
24577 }
24579 }
24581 /* If parm and arg aren't the same kind of thing (template, type, or
24582 expression), fail early. */
24586 /* Immediately reject some pairs that won't unify because of
24587 cv-qualification mismatches. */
24590 /* It is the elements of the array which hold the cv quals of an array
24591 type, and the elements might be template type parms. We'll check
24592 when we recurse. */
24594 /* We check the cv-qualifiers when unifying with template type
24595 parameters below. We want to allow ARG `const T' to unify with
24596 PARM `T' for example, when computing which of two templates
24597 is more specialized, for example. */
24606 /* PMFs recurse at the same level, so don't strip this yet. */
24614 {
24618 /* In a type which contains a nested-name-specifier, template
24619 argument values cannot be deduced for template parameters used
24620 within the nested-name-specifier. */
24632 /* The PARM is not one we're trying to unify. Just check
24633 to see if it matches ARG. */
24634 {
24639 else
24641 }
24648 /* Check for mixed types and values. */
24656 {
24659 {
24660 /* First try to match ARG directly. */
24662 explain_p);
24664 {
24665 /* Otherwise, look for a suitable base of ARG, as below. */
24672 }
24673 }
24674 /* ARG must be constructed from a template class or a template
24675 template parameter. */
24680 /* Deduce arguments T, i from TT<T> or TT<i>. */
24686 /* If the template is a template template parameter, use the
24687 TEMPLATE_TEMPLATE_PARM for matching. */
24690 /* Fall through to deduce template name. */
24691 }
24695 {
24696 /* Deduce template name TT from TT, TT<>, TT<T> and TT<i>. */
24698 /* Simple cases: Value already set, does match or doesn't. */
24703 }
24704 else
24705 {
24706 /* If PARM is `const T' and ARG is only `int', we don't have
24707 a match unless we are allowing additional qualification.
24708 If ARG is `const int' and PARM is just `T' that's OK;
24709 that binds `const int' to `T'. */
24714 /* Consider the case where ARG is `const volatile int' and
24715 PARM is `const T'. Then, T should be `volatile int'. */
24716 arg = cp_build_qualified_type
24721 /* Simple cases: Value already set, does match or doesn't. */
24727 /* Make sure that ARG is not a variable-sized array. (Note
24728 that were talking about variable-sized arrays (like
24729 `int[n]'), rather than arrays of unknown size (like
24730 `int[]').) We'll get very confused by such a type since
24731 the bound of the array is not constant, and therefore
24732 not mangleable. Besides, such types are not allowed in
24733 ISO C++, so we can do as we please here. We do allow
24734 them for 'auto' deduction, since that isn't ABI-exposed. */
24738 /* Strip typedefs as in convert_template_argument. */
24740 }
24742 /* If ARG is a parameter pack or an expansion, we cannot unify
24743 against it unless PARM is also a parameter pack. */
24748 /* If the argument deduction results is a METHOD_TYPE,
24749 then there is a problem.
24750 METHOD_TYPE doesn't map to any real C++ type the result of
24751 the deduction cannot be of that type. */
24765 {
24766 /* The PARM is not one we're trying to unify. Just check
24767 to see if it matches ARG. */
24773 }
24779 {
24783 /* We're deducing from an array bound, the type doesn't matter.
24784 This conversion should match the one below. */
24790 }
24792 /* [temp.deduct.type] If, in the declaration of a function template
24793 with a non-type template-parameter, the non-type
24794 template-parameter is used in an expression in the function
24795 parameter-list and, if the corresponding template-argument is
24796 deduced, the template-argument type shall match the type of the
24797 template-parameter exactly, except that a template-argument
24798 deduced from an array bound may be of any integral type.
24799 The non-type parameter might use already deduced type parameters. */
24802 /* We don't have enough levels of args to do any substitution. This
24804 else
24805 {
24811 {
24814 LOOKUP_NORMAL,
24818 }
24819 }
24823 /* Template-parameter dependent expression. Just accept it for now.
24824 It will later be processed in convert_template_argument. */
24825 ;
24829 /* OK. Ignore top-level quals here because a class-type template
24833 /* Convert the ARG to the type of PARM; the deduced non-type
24834 template argument must exactly match the types of the
24835 corresponding parameter. This conversion should match the
24836 one above. */
24839 {
24840 /* We haven't deduced the type of this parameter yet. */
24842 /* We deduce from array bounds in try_array_deduction. */
24845 {
24846 /* Deduce it from the non-type argument. As above, ignore
24847 top-level quals here too. */
24852 /* Now check whether the type of this parameter is still
24853 dependent, and give up if so. */
24859 }
24860 else
24861 /* Try again later. */
24863 }
24864 else
24867 /* If ARG is a parameter pack or an expansion, we cannot unify
24868 against it unless PARM is also a parameter pack. */
24873 {
24876 }
24881 {
24882 /* A pointer-to-member constant can be unified only with
24883 another constant. */
24887 /* Just unify the class member. It would be useless (and possibly
24888 wrong, depending on the strict flags) to unify also
24889 PTRMEM_CST_CLASS, because we want to be sure that both parm and
24890 arg refer to the same variable, even if through different
24891 classes. For instance:
24893 struct A { int x; };
24894 struct B : A { };
24896 Unification of &A::x and &B::x must succeed. */
24899 }
24902 {
24906 /* [temp.deduct.call]
24908 A can be another pointer or pointer to member type that can
24909 be converted to the deduced A via a qualification
24910 conversion (_conv.qual_).
24912 We pass down STRICT here rather than UNIFY_ALLOW_NONE.
24913 This will allow for additional cv-qualification of the
24914 pointed-to types if appropriate. */
24917 /* The derived-to-base conversion only persists through one
24918 level of pointers. */
24923 }
24956 /* We have already checked cv-qualification at the top of the
24957 function. */
24961 /* As far as unification is concerned, this wins. Later checks
24962 will invalidate it if necessary. */
24965 /* Types INTEGER_CST and MINUS_EXPR can come from array bounds. */
24966 /* Type INTEGER_CST can come from ordinary constant template args. */
24982 {
24992 /* Check for pack expansions in the parameters. */
24994 {
24996 {
24998 /* We can unify against something with a trailing
24999 parameter pack. */
25001 else
25002 /* [temp.deduct.type]/9: If the template argument list of
25003 P contains a pack expansion that is not the last
25004 template argument, the entire template argument list
25005 is a non-deduced context. */
25007 }
25008 }
25010 /* If we don't have enough arguments to satisfy the parameters
25011 (not counting the pack expression at the end), or we have
25012 too many arguments for a parameter list that doesn't end in
25013 a pack expression, we can't unify. */
25019 /* Unify all of the parameters that precede the (optional)
25020 pack expression. */
25022 {
25027 }
25030 DEDUCE_EXACT,
25033 }
25041 {
25049 }
25054 {
25058 {
25059 /* First, we try to unify the PARM and ARG directly. */
25064 {
25065 /* Fallback to the special case allowed in
25066 [temp.deduct.call]:
25068 If P is a class, and P has the form
25069 template-id, then A can be a derived class of
25070 the deduced A. Likewise, if P is a pointer to
25071 a class of the form template-id, A can be a
25072 pointer to a derived class pointed to by the
25073 deduced A. */
25079 {
25080 /* Don't give the derived diagnostic if we're
25081 already dealing with the same template. */
25082 bool same_template
25088 }
25089 }
25090 }
25094 /* Perhaps PARM is something like S<U> and ARG is S<int>.
25095 Then, we should unify `int' and `U'. */
25097 else
25098 /* There's no chance of unification succeeding. */
25106 else
25108 }
25115 {
25118 tree a;
25124 /* CV qualifications for methods can never be deduced, they must
25125 match exactly. We need to check them explicitly here,
25126 because type_unification_real treats them as any other
25127 cv-qualified parameter. */
25129 && (!check_cv_quals_for_unify
25157 {
25167 else
25168 {
25171 /* Here "less cv-qual" means the deduced arg (i.e. parm) has
25172 /more/ noexcept, since function pointer conversions are the
25173 reverse of qualification conversions. */
25178 else
25180 }
25181 }
25183 {
25184 /* As for noexcept. */
25191 else
25193 }
25196 }
25199 /* Unify a pointer to member with a pointer to member function, which
25200 deduces the type of the member as a function type. */
25202 {
25203 /* Check top-level cv qualifiers */
25211 /* Determine the type of the function we are unifying against. */
25215 }
25226 /* CONST_DECL should already have been folded to its DECL_INITIAL. */
25232 /* Matched cases are handled by the ARG == PARM test above. */
25236 /* We might get a variable as a non-type template argument in parm if the
25237 corresponding parameter is type-dependent. Make any necessary
25238 adjustments based on whether arg is a reference. */
25242 {
25247 }
25248 /* Now use the normal expression code to check whether they match. */
25259 /* Cannot deduce anything from TYPEOF_TYPE, DECLTYPE_TYPE,
25260 or TRAIT_TYPE nodes. */
25264 /* Unification fails if we hit an error node. */
25269 {
25279 }
25280 /* FALLTHRU */
25283 /* An unresolved overload is a nondeduced context. */
25289 expr:
25290 /* We must be looking at an expression. This can happen with
25291 something like:
25293 template <int I>
25294 void foo(S<I>, S<I + 2>);
25296 or
25298 template<typename T>
25299 void foo(A<T, T{}>);
25301 This is a "non-deduced context":
25303 [deduct.type]
25305 The non-deduced contexts are:
25307 --A non-type template argument or an array bound in which
25308 a subexpression references a template parameter.
25310 In these cases, we assume deduction succeeded, but don't
25311 actually infer any unifications. */
25316 else
25318 }
25319 }
25320 #undef RECUR_AND_CHECK_FAILURE
25321 \f
25322 /* Note that DECL can be defined in this translation unit, if
25323 required. */
25325 static void
25327 {
25328 tree clone;
25332 }
25334 /* Called if RESULT is explicitly instantiated, or is a member of an
25335 explicitly instantiated class. */
25337 void
25339 {
25342 /* If this entity has already been written out, it's too late to
25343 make any modifications. */
25347 /* consteval functions are never emitted. */
25352 /* For anonymous namespace we don't need to do anything. */
25354 {
25357 }
25360 /* The TREE_PUBLIC flag for function declarations will have been
25361 set correctly by tsubst. */
25365 {
25368 }
25369 else
25370 {
25373 /* Always make artificials weak. */
25376 /* For WIN32 we also want to put explicit instantiations in
25377 linkonce sections. */
25382 /* If the function has already been instantiated, clear DECL_EXTERNAL,
25383 since start_preparsed_function wouldn't have if we had an earlier
25384 extern explicit instantiation. */
25386 }
25388 /* If EXTERN_P, then this function will not be emitted -- unless
25389 followed by an explicit instantiation, at which point its linkage
25390 will be adjusted. If !EXTERN_P, then this function will be
25391 emitted here. In neither circumstance do we want
25392 import_export_decl to adjust the linkage. */
25394 }
25396 /* Subroutine of more_specialized_fn: check whether TARGS is missing any
25397 important template arguments. If any are missing, we check whether
25398 they're important by using error_mark_node for substituting into any
25399 args that were used for partial ordering (the ones between ARGS and END)
25400 and seeing if it bubbles up. */
25402 static bool
25404 {
25408 {
25411 }
25413 {
25417 }
25419 }
25421 /* Given two function templates PAT1 and PAT2, return:
25423 1 if PAT1 is more specialized than PAT2 as described in [temp.func.order].
25424 -1 if PAT2 is more specialized than PAT1.
25425 0 if neither is more specialized.
25427 LEN indicates the number of parameters we should consider
25428 (defaulted parameters should not be considered).
25430 The 1998 std underspecified function template partial ordering, and
25431 DR214 addresses the issue. We take pairs of arguments, one from
25432 each of the templates, and deduce them against each other. One of
25433 the templates will be more specialized if all the *other*
25434 template's arguments deduce against its arguments and at least one
25435 of its arguments *does* *not* deduce against the other template's
25436 corresponding argument. Deduction is done as for class templates.
25437 The arguments used in deduction have reference and top level cv
25438 qualifiers removed. Iff both arguments were originally reference
25439 types *and* deduction succeeds in both directions, an lvalue reference
25440 wins against an rvalue reference and otherwise the template
25441 with the more cv-qualified argument wins for that pairing (if
25442 neither is more cv-qualified, they both are equal). Unlike regular
25443 deduction, after all the arguments have been deduced in this way,
25444 we do *not* verify the deduced template argument values can be
25445 substituted into non-deduced contexts.
25447 The logic can be a bit confusing here, because we look at deduce1 and
25448 targs1 to see if pat2 is at least as specialized, and vice versa; if we
25449 can find template arguments for pat1 to make arg1 look like arg2, that
25450 means that arg2 is at least as specialized as arg1. */
25452 int
25454 {
25467 /* C++17 [temp.func.order]/3 (CWG532)
25469 If only one of the function templates M is a non-static member of some
25470 class A, M is considered to have a new first parameter inserted in its
25471 function parameter list. Given cv as the cv-qualifiers of M (if any), the
25472 new parameter is of type "rvalue reference to cv A" if the optional
25473 ref-qualifier of M is && or if M has no ref-qualifier and the first
25474 parameter of the other template has rvalue reference type. Otherwise, the
25475 new parameter is of type "lvalue reference to cv A". */
25478 {
25479 /* Note C++20 DR2445 extended the above to static member functions, but
25480 I think think the old G++ behavior of just skipping the object
25481 parameter when comparing to a static member function was better, so
25482 let's stick with that for now. This is CWG2834. --jason 2023-12 */
25484 {
25487 }
25490 }
25493 {
25494 /* Note DR2445 also (IMO wrongly) removed the "only one" above, which
25495 would break e.g. cpp1y/lambda-generic-variadic5.C. */
25496 len--;
25499 }
25502 {
25503 /* The other is a non-member or explicit object member function;
25504 rewrite the implicit object parameter to a reference. */
25513 {
25519 }
25522 }
25524 /* If only one is a conversion operator, they are unordered. */
25528 /* Consider the return type for a conversion function */
25530 {
25533 len++;
25534 }
25536 processing_template_decl++;
25542 /* Stop when an ellipsis is seen. */
25544 {
25555 {
25556 /* When both arguments are pack expansions, we need only
25557 unify the patterns themselves. */
25561 /* This is the last comparison we need to do. */
25563 }
25566 {
25570 }
25573 {
25577 }
25583 {
25589 /* Setup the parameter vector, which contains only ARG1. */
25592 /* Setup the argument vector, which contains the remaining
25593 arguments. */
25602 /* We cannot deduce in the other direction, because ARG1 is
25603 a pack expansion but ARG2 is not. */
25605 }
25607 {
25613 /* Setup the parameter vector, which contains only ARG1. */
25616 /* Setup the argument vector, which contains the remaining
25617 arguments. */
25626 /* We cannot deduce in the other direction, because ARG2 is
25627 a pack expansion but ARG1 is not.*/
25629 }
25631 else
25632 {
25633 /* The normal case, where neither argument is a pack
25634 expansion. */
25641 }
25643 /* If we couldn't deduce arguments for tparms1 to make arg1 match
25644 arg2, then arg2 is not as specialized as arg1. */
25650 /* "If, for a given type, deduction succeeds in both directions
25651 (i.e., the types are identical after the transformations above)
25652 and both P and A were reference types (before being replaced with
25653 the type referred to above):
25654 - if the type from the argument template was an lvalue reference and
25655 the type from the parameter template was not, the argument type is
25656 considered to be more specialized than the other; otherwise,
25657 - if the type from the argument template is more cv-qualified
25658 than the type from the parameter template (as described above),
25659 the argument type is considered to be more specialized than the other;
25660 otherwise,
25661 - neither type is more specialized than the other." */
25664 {
25666 {
25669 else
25671 }
25673 {
25678 }
25679 }
25682 /* We've failed to deduce something in either direction.
25683 These must be unordered. */
25688 /* We have already processed all of the arguments in our
25689 handing of the pack expansion type. */
25694 }
25696 /* "In most cases, all template parameters must have values in order for
25697 deduction to succeed, but for partial ordering purposes a template
25698 parameter may remain without a value provided it is not used in the
25699 types being used for partial ordering."
25701 Thus, if we are missing any of the targs1 we need to substitute into
25702 origs1, then pat2 is not as specialized as pat1. This can happen when
25703 there is a nondeduced context. */
25709 processing_template_decl--;
25711 /* If both deductions succeed, the partial ordering selects the more
25712 constrained template. */
25713 /* P2113: If the corresponding template-parameters of the
25714 template-parameter-lists are not equivalent ([temp.over.link]) or if
25715 the function parameters that positionally correspond between the two
25716 templates are not of the same type, neither template is more
25717 specialized than the other. */
25722 {
25728 }
25730 /* All things being equal, if the next argument is a pack expansion
25731 for one function but not for the other, prefer the
25732 non-variadic function. FIXME this is bogus; see c++/41958. */
25736 {
25739 }
25745 else
25747 }
25749 /* Determine which of two partial specializations of TMPL is more
25750 specialized.
25752 PAT1 is a TREE_LIST whose TREE_VALUE is the TEMPLATE_DECL corresponding
25753 to the first partial specialization. The TREE_PURPOSE is the
25754 innermost set of template parameters for the partial
25755 specialization. PAT2 is similar, but for the second template.
25757 Return 1 if the first partial specialization is more specialized;
25758 -1 if the second is more specialized; 0 if neither is more
25759 specialized.
25761 See [temp.class.order] for information about determining which of
25762 two templates is more specialized. */
25764 static int
25766 {
25767 tree targs;
25776 /* Just like what happens for functions, if we are ordering between
25777 different template specializations, we may encounter dependent
25778 types in the arguments, and we need our dependency check functions
25779 to behave correctly. */
25783 {
25786 }
25790 {
25793 }
25796 /* If both deductions succeed, the partial ordering selects the more
25797 constrained template. */
25801 /* In the case of a tie where at least one of the templates
25802 has a parameter pack at the end, the template with the most
25803 non-packed parameters wins. */
25805 && any_deductions
25808 {
25814 /* We don't count the pack expansion at the end. */
25824 }
25827 }
25829 /* Return the template arguments that will produce the function signature
25830 DECL from the function template FN, with the explicit template
25831 arguments EXPLICIT_ARGS. If CHECK_RETTYPE is true, the return type must
25832 also match. Return NULL_TREE if no satisfactory arguments could be
25833 found. */
25835 static tree
25837 {
25841 tree decl_arg_types;
25844 tree arg;
25848 /* Never do unification on the 'this' parameter. */
25870 }
25872 /* Return the innermost template arguments that, when applied to a partial
25873 specialization SPEC_TMPL of TMPL, yield the ARGS.
25875 For example, suppose we have:
25877 template <class T, class U> struct S {};
25878 template <class T> struct S<T*, int> {};
25880 Then, suppose we want to get `S<double*, int>'. SPEC_TMPL will be the
25881 partial specialization and the ARGS will be {double*, int}. The resulting
25882 vector will be {double}, indicating that `T' is bound to `double'. */
25884 static tree
25886 {
25888 tree spec_args
25891 tree deduced_args;
25892 tree innermost_deduced_args;
25896 {
25900 innermost_deduced_args);
25901 }
25902 else
25906 again:
25915 {
25917 {
25923 }
25925 }
25928 {
25931 }
25933 /* Verify that nondeduced template arguments agree with the type
25934 obtained from argument deduction.
25936 For example:
25938 struct A { typedef int X; };
25939 template <class T, class U> struct C {};
25940 template <class T> struct C<T, typename T::X> {};
25942 Then with the instantiation `C<A, int>', we can deduce that
25943 `T' is `A' but unify () does not check whether `typename T::X'
25944 is `int'. */
25955 /* We only need to check the innermost arguments; the other
25956 arguments will always agree. */
25961 /* Now that we have bindings for all of the template arguments,
25962 ensure that the arguments deduced for the template template
25963 parameters have compatible template parameter lists. See the use
25964 of template_template_parm_bindings_ok_p in fn_type_unification
25965 for more information. */
25970 }
25972 // Compare two function templates T1 and T2 by deducing bindings
25973 // from one against the other. If both deductions succeed, compare
25974 // constraints to see which is more constrained.
25975 static int
25977 {
25982 {
25985 }
25988 {
25991 }
25993 // If both deductions succeed, then one may be more constrained.
25998 }
26000 /* TEMPLATES is a TREE_LIST. Each TREE_VALUE is a TEMPLATE_DECL.
26001 Return the TREE_LIST node with the most specialized template, if
26002 any. If there is no most specialized template, the error_mark_node
26003 is returned.
26005 Note that this function does not look at, or modify, the
26006 TREE_PURPOSE or TREE_TYPE of any of the nodes. Since the node
26007 returned is one of the elements of INSTANTIATIONS, callers may
26008 store information in the TREE_PURPOSE or TREE_TYPE of the nodes,
26009 and retrieve it from the value returned. */
26011 tree
26013 {
26020 {
26026 {
26027 /* Equally specialized, move to next function. If there
26028 is no next function, nothing's most specialized. */
26033 }
26034 }
26037 /* Now verify that champ is better than everything earlier in the
26038 instantiation list. */
26041 {
26044 }
26045 }
26047 processing_template_decl--;
26053 }
26055 /* If DECL is a specialization of some template, return the most
26056 general such template. Otherwise, returns NULL_TREE.
26058 For example, given:
26060 template <class T> struct S { template <class U> void f(U); };
26062 if TMPL is `template <class U> void S<int>::f(U)' this will return
26063 the full template. This function will not trace past partial
26064 specializations, however. For example, given in addition:
26066 template <class T> struct S<T*> { template <class U> void f(U); };
26068 if TMPL is `template <class U> void S<int*>::f(U)' this will return
26069 `template <class T> template <class U> S<T*>::f(U)'. */
26071 tree
26073 {
26075 {
26078 /* The TI_TEMPLATE can be an IDENTIFIER_NODE for a
26079 template friend, or a FIELD_DECL for a capture pack. */
26082 }
26087 /* Look for more and more general templates. */
26089 {
26090 /* The DECL_TI_TEMPLATE can be an IDENTIFIER_NODE in some cases.
26091 (See cp-tree.h for details.) */
26100 /* Stop if we run into an explicitly specialized class template. */
26107 }
26110 }
26112 /* Return the most specialized of the template partial specializations
26113 which can produce TARGET, a specialization of some class or variable
26114 template. The value returned is a TEMPLATE_INFO; the TI_TEMPLATE is a
26115 TEMPLATE_DECL node corresponding to the partial specialization, while
26116 the TI_ARGS is the set of template arguments that must be substituted
26117 into the template pattern in order to generate TARGET. The result is
26118 cached in the TI_PARTIAL_INFO of the corresponding TEMPLATE_INFO unless
26119 RECHECKING is true.
26121 If the choice of partial specialization is ambiguous, a diagnostic
26122 is issued, and the error_mark_node is returned. If there are no
26123 partial specializations matching TARGET, then NULL_TREE is
26124 returned, indicating that the primary template should be used. */
26126 tree
26129 {
26133 {
26138 }
26140 {
26144 }
26146 {
26151 }
26152 else
26159 && tinfo
26166 /* There are no partial specializations of this template. */
26172 /* For determining which partial specialization to use, only the
26173 innermost args are interesting. */
26176 {
26179 }
26181 /* The caller hasn't called push_to_top_level yet, but we need
26182 get_partial_spec_bindings to be done in non-template context so that we'll
26183 fully resolve everything. */
26184 processing_template_decl_sentinel ptds;
26188 {
26191 tree spec_tmpl;
26193 {
26194 /* Substitute in the template args from the enclosing class. */
26200 }
26201 else
26206 {
26210 /* Keep the candidate only if its constraints are satisfied. */
26213 }
26214 }
26222 {
26225 ;
26226 else
26227 {
26229 {
26232 {
26235 }
26236 }
26238 }
26239 }
26243 {
26246 {
26249 }
26250 }
26253 {
26260 else
26264 {
26269 }
26272 }
26278 }
26280 /* Explicitly instantiate DECL. */
26282 void
26284 {
26289 /* An error occurred, for which grokdeclarator has already issued
26290 an appropriate message. */
26293 {
26296 }
26298 {
26301 else
26304 }
26310 {
26311 /* There is an asymmetry here in the way VAR_DECLs and
26312 FUNCTION_DECLs are handled by grokdeclarator. In the case of
26313 the latter, the DECL we get back will be marked as a
26314 template instantiation, and the appropriate
26315 DECL_TEMPLATE_INFO will be set up. This does not happen for
26316 VAR_DECLs so we do the lookup here. Probably, grokdeclarator
26317 should handle VAR_DECLs as it currently handles
26318 FUNCTION_DECLs. */
26320 {
26323 }
26326 {
26329 }
26331 {
26336 }
26337 }
26339 {
26342 }
26343 else
26346 /* Check for various error cases. Note that if the explicit
26347 instantiation is valid the RESULT will currently be marked as an
26348 *implicit* instantiation; DECL_EXPLICIT_INSTANTIATION is not set
26349 until we get here. */
26352 {
26353 /* DR 259 [temp.spec].
26355 Both an explicit instantiation and a declaration of an explicit
26356 specialization shall not appear in a program unless the explicit
26357 instantiation follows a declaration of the explicit specialization.
26359 For a given set of template parameters, if an explicit
26360 instantiation of a template appears after a declaration of an
26361 explicit specialization for that template, the explicit
26362 instantiation has no effect. */
26364 }
26366 {
26367 /* [temp.spec]
26369 No program shall explicitly instantiate any template more
26370 than once.
26372 We check DECL_NOT_REALLY_EXTERN so as not to complain when
26373 the first instantiation was `extern' and the second is not,
26374 and EXTERN_P for the opposite case. */
26377 /* If an "extern" explicit instantiation follows an ordinary
26378 explicit instantiation, the template is instantiated. */
26381 }
26383 {
26386 }
26388 {
26391 }
26394 ;
26396 {
26399 "ISO C++ 1998 forbids the use of %<extern%> on explicit "
26402 }
26403 else
26411 }
26413 static void
26415 {
26421 {
26424 }
26425 }
26427 /* Perform an explicit instantiation of template class T. STORAGE, if
26428 non-null, is the RID for extern, inline or static. COMPLAIN is
26429 nonzero if this is called from the parser, zero if called recursively,
26430 since the standard is unclear (as detailed below). */
26432 void
26434 {
26436 {
26440 else
26443 }
26448 {
26451 t);
26453 }
26455 /* At most one of these will be true. */
26461 {
26463 {
26466 "ISO C++ 1998 forbids the use of %<extern%> on "
26468 }
26469 else
26471 "ISO C++ forbids the use of %qE"
26480 else
26482 storage);
26483 }
26486 /* DR 259 [temp.spec].
26488 Both an explicit instantiation and a declaration of an explicit
26489 specialization shall not appear in a program unless the
26490 explicit instantiation follows a declaration of the explicit
26491 specialization.
26493 For a given set of template parameters, if an explicit
26494 instantiation of a template appears after a declaration of an
26495 explicit specialization for that template, the explicit
26496 instantiation has no effect. */
26500 {
26501 /* We've already instantiated the template. */
26503 /* [temp.spec]
26505 No program shall explicitly instantiate any template more
26506 than once.
26508 If EXTERN_P then this is ok. */
26514 }
26522 /* In contrast to implicit instantiation, where only the
26523 declarations, and not the definitions, of members are
26524 instantiated, we have here:
26526 [temp.explicit]
26528 An explicit instantiation that names a class template
26529 specialization is also an explicit instantiation of the same
26530 kind (declaration or definition) of each of its members (not
26531 including members inherited from base classes and members
26532 that are templates) that has not been previously explicitly
26533 specialized in the translation unit containing the explicit
26534 instantiation, provided that the associated constraints, if
26535 any, of that member are satisfied by the template arguments
26536 of the explicit instantiation. */
26540 && !static_p
26544 {
26549 }
26551 {
26557 }
26558 }
26560 /* Given a function DECL, which is a specialization of TMPL, modify
26561 DECL to be a re-instantiation of TMPL with the same template
26562 arguments. TMPL should be the template into which tsubst'ing
26563 should occur for DECL, not the most general template.
26565 One reason for doing this is a scenario like this:
26567 template <class T>
26568 void f(const T&, int i);
26570 void g() { f(3, 7); }
26572 template <class T>
26573 void f(const T& t, const int i) { }
26575 Note that when the template is first instantiated, with
26576 instantiate_template, the resulting DECL will have no name for the
26577 first parameter, and the wrong type for the second. So, when we go
26578 to instantiate the DECL, we regenerate it. */
26580 static void
26582 {
26583 /* The arguments used to instantiate DECL, from the most general
26584 template. */
26587 /* Make sure that we can see identifiers, and compute access correctly. */
26591 {
26592 tree specs;
26596 /* Don't bother with this for unique friends that can't be redeclared and
26597 might change type if regenerated (PR69836). */
26601 /* Use the source location of the definition. */
26609 /* Instantiate a dynamic exception-specification. noexcept will be
26610 handled below. */
26613 {
26619 specs);
26620 }
26622 /* Merge parameter declarations. */
26626 {
26633 }
26636 {
26637 /* If we're regenerating a specialization, the contracts will have
26638 been copied from the most general template. Replace those with
26639 the ones from the actual specialization. */
26642 {
26645 }
26648 }
26650 /* Merge additional specifiers from the CODE_PATTERN. */
26656 }
26658 {
26667 }
26668 else
26671 done:
26673 }
26675 /* Return the TEMPLATE_DECL into which DECL_TI_ARGS(DECL) should be
26676 substituted to get DECL. */
26678 tree
26680 {
26683 /* Set TMPL to the template whose DECL_TEMPLATE_RESULT is the pattern
26684 for the instantiation. This is not always the most general
26685 template. Consider, for example:
26687 template <class T>
26688 struct S { template <class U> void f();
26689 template <> void f<int>(); };
26691 and an instantiation of S<double>::f<int>. We want TD to be the
26692 specialization S<T>::f<int>, not the more general S<T>::f<U>. */
26694 more general template. */
26696 /* We must also deal with friend templates. Given:
26698 template <class T> struct S {
26699 template <class U> friend void f() {};
26700 };
26702 S<int>::f<U> say, is not an instantiation of S<T>::f<U>,
26703 so far as the language is concerned, but that's still
26704 where we get the pattern for the instantiation from. On
26705 other hand, if the definition comes outside the class, say:
26707 template <class T> struct S {
26708 template <class U> friend void f();
26709 };
26710 template <class U> friend void f() {}
26712 we don't need to look any further. That's what the check for
26713 DECL_INITIAL is for. */
26717 {
26718 /* The present template, TD, should not be a definition. If it
26719 were a definition, we should be using it! Note that we
26720 cannot restructure the loop to just keep going until we find
26721 a template with a definition, since that might go too far if
26722 a specialization was declared, but not defined. */
26724 /* Fetch the more general template. */
26726 }
26729 }
26731 /* Returns true if we need to instantiate this template instance even if we
26732 know we aren't going to emit it. */
26734 bool
26736 {
26737 /* We always instantiate inline functions so that we can inline them. An
26738 explicit instantiation declaration prohibits implicit instantiation of
26739 non-inline functions. With high levels of optimization, we would
26740 normally inline non-inline functions -- but we're not allowed to do
26741 that for "extern template" functions. Therefore, we check
26742 DECL_DECLARED_INLINE_P, rather than possibly_inlined_p. */
26746 /* And we need to instantiate static data members so that
26747 their initializers are available in integral constant
26748 expressions. */
26751 }
26753 /* If FN has a noexcept-specifier that hasn't been instantiated yet,
26754 instantiate it now, modifying TREE_TYPE (fn). Returns false on
26755 error, true otherwise. */
26757 bool
26759 {
26763 /* Don't instantiate a noexcept-specification from template context. */
26773 {
26775 /* We're in start_preparsed_function, keep going. */
26782 }
26793 /* For a member friend template we can get a TEMPLATE_DECL. Let's use
26794 its FUNCTION_DECL for the rest of this function -- push_access_scope
26795 doesn't accept TEMPLATE_DECLs. */
26797 {
26800 }
26803 {
26808 }
26810 {
26814 {
26817 /* This might have failed because of an unparsed DMI, so
26818 let's try again later. */
26820 }
26822 {
26823 /* If hash_set::add returns true, the element was already there. */
26828 fn);
26830 }
26832 {
26840 {
26841 /* If needed, set current_class_ptr for the benefit of
26842 tsubst_copy/PARM_DECL. */
26847 }
26849 /* If this function is represented by a TEMPLATE_DECL, then
26850 the deferred noexcept-specification might still contain
26851 dependent types, even after substitution. And we need the
26852 dependency check functions to work in build_noexcept_spec. */
26856 /* Do deferred instantiation of the noexcept-specifier. */
26861 /* Build up the noexcept-specification. */
26871 }
26872 else
26877 }
26880 {
26881 /* This failed with a hard error, so let's go with false. */
26884 }
26891 }
26893 /* We're starting to process the function INST, an instantiation of PATTERN;
26894 add their parameters to local_specializations. */
26896 void
26898 {
26902 {
26906 }
26908 {
26910 {
26913 }
26914 else
26915 {
26916 /* Register the (value) argument pack as a specialization of
26917 TMPL_PARM, then move on. */
26920 }
26921 }
26923 }
26925 /* Instantiate the body of D using PATTERN with ARGS. We have
26926 already determined PATTERN is the correct template to use.
26927 NESTED_P is true if this is a nested function, in which case
26928 PATTERN will be a FUNCTION_DECL not a TEMPLATE_DECL. */
26930 static void
26932 {
26937 {
26940 }
26941 else
26942 /* Only OMP reductions are nested. */
26954 {
26955 /* The variable might be a lambda's extra scope, and that
26956 lambda's visibility depends on D's. */
26959 }
26961 /* Mark D as instantiated so that recursive calls to
26962 instantiate_decl do not try to instantiate it again. */
26966 /* Regenerate the declaration in case the template has been modified
26967 by a subsequent redeclaration. */
26970 /* We already set the file and line above. Reset them now in case
26971 they changed as a result of calling regenerate_decl_from_template. */
26975 {
26976 /* Clear out DECL_RTL; whatever was there before may not be right
26977 since we've reset the type of the declaration. */
26981 /* The initializer is placed in DECL_INITIAL by
26982 regenerate_decl_from_template so we don't need to
26983 push/pop_access_scope again here. Pull it out so that
26984 cp_finish_decl can process it. */
26990 /* Clear DECL_EXTERNAL so that cp_finish_decl will process the
26991 initializer. That function will defer actual emission until
26992 we have a chance to determine linkage. */
26995 /* Enter the scope of D so that access-checking works correctly. */
27005 }
27009 {
27010 /* Set up the list of local specializations. */
27014 /* Set up context. */
27017 else
27018 {
27022 }
27024 /* Create substitution entries for the parameters. */
27027 /* Substitute into the body of the function. */
27031 else
27032 {
27036 /* Set the current input_location to the end of the function
27037 so that finish_function knows where we are. */
27038 input_location
27041 /* Remember if we saw an infinite loop in the template. */
27042 current_function_infinite_loop
27044 }
27046 /* Finish the function. */
27049 else
27050 {
27053 }
27057 }
27059 /* We're not deferring instantiation any more. */
27067 }
27069 /* Produce the definition of D, a _DECL generated from a template. If
27070 DEFER_OK is true, then we don't have to actually do the
27071 instantiation now; we just have to do it sometime. Normally it is
27072 an error if this is an explicit instantiation but D is undefined.
27073 EXPL_INST_CLASS_MEM_P is true iff D is a member of an explicitly
27074 instantiated class template. */
27076 tree
27078 {
27080 tree gen_args;
27081 tree args;
27082 tree td;
27083 tree code_pattern;
27084 tree spec;
27085 tree gen_tmpl;
27091 /* This function should only be used to instantiate templates for
27092 functions and static member variables. */
27095 /* A concept is never instantiated. */
27101 /* We may have a pending instantiation of D itself. */
27104 /* Variables are never deferred; if instantiation is required, they
27105 are instantiated right away. That allows for better code in the
27106 case that an expression refers to the value of the variable --
27107 if the variable has a constant value the referring expression can
27108 take advantage of that fact. */
27112 /* Don't instantiate cloned functions. Instead, instantiate the
27113 functions they cloned. */
27122 /* D has already been instantiated or explicitly specialized, so
27123 there's nothing for us to do here.
27125 It might seem reasonable to check whether or not D is an explicit
27126 instantiation, and, if so, stop here. But when an explicit
27127 instantiation is deferred until the end of the compilation,
27128 DECL_EXPLICIT_INSTANTIATION is set, even though we still need to do
27129 the instantiation. */
27132 /* Check to see whether we know that this template will be
27133 instantiated in some other file, as with "extern template"
27134 extension. */
27137 /* In general, we do not instantiate such templates. */
27144 /* We should already have the extra args. */
27148 /* And what's in the hash table should match D. */
27150 == d
27153 /* This needs to happen before any tsubsting. */
27159 /* Set TD to the template whose DECL_TEMPLATE_RESULT is the pattern
27160 for the instantiation. */
27165 {
27166 /* Look up an explicit specialization, if any. */
27169 {
27172 }
27173 }
27177 /* We should never be trying to instantiate a member of a class
27178 template or partial specialization. */
27183 /* In the case of a friend template whose definition is provided
27184 outside the class, we may have too many arguments. Drop the
27185 ones we don't need. The same is true for specializations. */
27186 args = get_innermost_template_args
27190 {
27196 }
27197 else
27198 {
27202 else
27204 }
27206 /* We may be in the middle of deferred access check. Disable it now. */
27209 /* Unless an explicit instantiation directive has already determined
27210 the linkage of D, remember that a definition is available for
27211 this entity. */
27221 /* If D is a member of an explicitly instantiated class template,
27222 and no definition is available, treat it like an implicit
27223 instantiation. */
27226 {
27227 /* Leave linkage flags alone on instantiations with anonymous
27228 visibility. */
27230 {
27233 }
27235 }
27237 /* Defer all other templates, unless we have been explicitly
27238 forbidden from doing so. */
27240 template. */
27241 ! pattern_defined
27242 /* If it's OK to postpone instantiation, do so. */
27243 || defer_ok
27244 /* If this is a static data member that will be defined
27245 elsewhere, we don't want to instantiate the entire data
27246 member, but we do want to instantiate the initializer so that
27247 we can substitute that elsewhere. */
27249 /* Handle here a deleted function too, avoid generating
27250 its body (c++/61080). */
27252 {
27253 /* The definition of the static data member is now required so
27254 we must substitute the initializer. */
27258 {
27259 tree ns;
27260 tree init;
27269 args,
27271 /* If instantiating the initializer involved instantiating this
27272 again, don't call cp_finish_decl twice. */
27274 {
27275 /* Make sure the initializer is still constant, in case of
27276 circular dependency (template/instantiate6.C). */
27277 const_init
27281 }
27285 }
27287 /* We restore the source position here because it's used by
27288 add_pending_template. */
27294 /* [temp.explicit]
27296 The definition of a non-exported function template, a
27297 non-exported member function template, or a non-exported
27298 member function or static data member of a class template
27299 shall be present in every translation unit in which it is
27300 explicitly instantiated. */
27304 /* If we're in unevaluated context, we just wanted to get the
27305 constant value; this isn't an odr use, so don't queue
27306 a full instantiation. */
27308 /* ??? Historically, we have instantiated inline functions, even
27309 when marked as "extern template". */
27312 }
27313 else
27314 {
27319 }
27326 }
27328 /* Run through the list of templates that we wish we could
27329 instantiate, and instantiate any we can. RETRIES is the
27330 number of times we retry pending template instantiation. */
27332 void
27334 {
27338 /* Instantiating templates may trigger vtable generation. This in turn
27339 may require further template instantiations. We place a limit here
27340 to avoid infinite loop. */
27342 {
27346 "template instantiation depth exceeds maximum of %d"
27347 " instantiating %q+D, possibly from virtual table generation"
27351 /* Pretend that we defined it. */
27354 }
27356 do
27357 {
27362 {
27367 {
27369 {
27384 }
27387 }
27388 else
27389 {
27392 {
27393 instantiation
27399 }
27403 }
27406 {
27407 /* If INSTANTIATION has been instantiated, then we don't
27408 need to consider it again in the future. */
27413 }
27414 else
27415 {
27418 }
27421 }
27423 }
27427 }
27429 /* Substitute ARGVEC into T, which is a list of initializers for
27430 either base class or a non-static data member. The TREE_PURPOSEs
27431 are DECLs, and the TREE_VALUEs are the initializer values. Used by
27432 instantiate_decl. */
27434 static tree
27436 {
27441 {
27442 tree decl;
27443 tree init;
27449 {
27450 tree expr;
27451 tree arg;
27453 /* Expand the base class expansion type into separate base
27454 classes. */
27456 tf_warning_or_error,
27457 NULL_TREE);
27461 /* We'll be building separate TREE_LISTs of arguments for
27462 each base. */
27468 /* Build a dummy EXPR_PACK_EXPANSION that will be used to
27469 expand each argument in the TREE_VALUE of t. */
27476 /* VOID_TYPE_NODE is used to indicate
27477 value-initialization. */
27478 {
27481 }
27482 else
27483 {
27484 /* Substitute parameter packs into each argument in the
27485 TREE_LIST. */
27488 {
27489 tree expanded_exprs;
27491 /* Expand the argument. */
27492 tree value;
27495 else
27496 {
27499 }
27500 expanded_exprs
27502 tf_warning_or_error,
27503 NULL_TREE);
27507 /* Prepend each of the expanded expressions to the
27508 corresponding TREE_LIST in EXPANDED_ARGUMENTS. */
27516 else
27521 }
27524 /* Reverse all of the TREE_LISTs in EXPANDED_ARGUMENTS,
27525 since we built them backwards. */
27527 {
27530 }
27531 }
27532 }
27535 {
27537 {
27541 }
27542 else
27543 {
27544 tree tmp;
27548 else
27562 /* If we had an initializer but it instantiated to nothing,
27563 value-initialize the object. This will only occur when
27564 the initializer was a pack expansion where the parameter
27565 packs used in that expansion were of length zero. */
27568 }
27572 {
27574 decl);
27576 }
27577 /* Look for a target constructor. */
27581 {
27584 {
27588 }
27590 }
27593 {
27595 /* Carry over the dummy TREE_TYPE node containing the source
27596 location. */
27600 }
27601 }
27602 }
27604 }
27606 /* Instantiate an enumerated type. TAG is the template type, NEWTAG
27607 is the instantiation (which should have been created with
27608 start_enum) and ARGS are the template arguments to use. */
27610 static void
27612 {
27613 tree e;
27619 {
27620 tree value;
27623 /* Note that in a template enum, the TREE_VALUE is the
27624 CONST_DECL, not the corresponding INTEGER_CST. */
27628 /* Give this enumeration constant the correct access. */
27631 /* Actually build the enumerator itself. Here we're assuming that
27632 enumerators can't have dependent attributes. */
27636 /* Attribute deprecated without an argument isn't sticky: it'll
27637 melt into a tree flag, so we need to propagate the flag here,
27638 since we just created a new enumerator. */
27641 }
27653 }
27655 /* DECL is a FUNCTION_DECL that is a template specialization. Return
27656 its type -- but without substituting the innermost set of template
27657 arguments. So, innermost set of template parameters will appear in
27658 the type. */
27660 tree
27662 {
27663 /* For a function, DECL_TI_TEMPLATE is partially instantiated. */
27665 }
27667 /* Return truthvalue if we're processing a template different from
27668 the last one involved in diagnostics. */
27669 bool
27671 {
27673 }
27675 /* Remember current template involved in diagnostics. */
27676 void
27678 {
27680 }
27684 {
27686 }
27688 /* Return TRUE if current_function_decl is being instantiated, false
27689 otherwise. */
27691 bool
27693 {
27697 }
27699 /* [temp.param] Check that template non-type parm TYPE is of an allowable
27700 type. Return false for ok, true for disallowed. Issue error and
27701 inform messages under control of COMPLAIN. */
27703 static bool
27705 {
27716 {
27718 {
27723 }
27725 }
27730 /* Fall through; before C++11 alias templates, a bound ttp
27733 /* Any other wildcard type not already handled above is allowed. */
27740 {
27748 {
27749 auto_diagnostic_group d;
27753 }
27755 }
27757 {
27762 }
27765 {
27768 else
27770 type);
27771 }
27773 }
27775 /* Returns true iff the noexcept-specifier for TYPE is value-dependent. */
27777 static bool
27779 {
27782 /* Treat DEFERRED_NOEXCEPT as non-dependent, since it doesn't
27783 affect overload resolution and treating it as dependent breaks
27784 things. Same for an unparsed noexcept expression. */
27791 }
27793 /* Returns TRUE if TYPE is dependent, in the sense of [temp.dep.type].
27794 Assumes that TYPE really is a type, and not the ERROR_MARK_NODE.*/
27796 static bool
27798 {
27799 tree scope;
27801 /* [temp.dep.type]
27803 A type is dependent if it is:
27805 -- a template parameter. Template template parameters are types
27806 for us (since TYPE_P holds true for them) so we handle
27807 them here. */
27811 /* -- a qualified-id with a nested-name-specifier which contains a
27812 class-name that names a dependent type or whose unqualified-id
27813 names a dependent type. */
27817 /* An alias template specialization can be dependent even if the
27818 resulting type is not. */
27822 /* -- a cv-qualified type where the cv-unqualified type is
27823 dependent.
27824 No code is necessary for this bullet; the code below handles
27825 cv-qualified types, and we don't want to strip aliases with
27826 TYPE_MAIN_VARIANT because of DR 1558. */
27827 /* -- a compound type constructed from any dependent type. */
27835 {
27836 tree arg_type;
27841 arg_type;
27847 /* A value-dependent noexcept-specifier makes the type dependent. */
27850 }
27851 /* -- an array type constructed from any dependent type or whose
27852 size is specified by a constant expression that is
27853 value-dependent.
27855 We checked for type- and value-dependence of the bounds in
27856 compute_array_index_type, so TYPE_DEPENDENT_P is already set. */
27858 {
27863 }
27865 /* -- a template-id in which either the template name is a template
27866 parameter ... */
27869 /* ... or any of the template arguments is a dependent type or
27870 an expression that is type-dependent or value-dependent. */
27872 && (any_dependent_template_arguments_p
27876 /* All TYPEOF_TYPEs, DECLTYPE_TYPEs, and TRAIT_TYPEs are
27877 dependent; if the argument of the `typeof' expression is not
27878 type-dependent, then it should already been have resolved. */
27884 /* A template argument pack is dependent if any of its packed
27885 arguments are. */
27887 {
27892 }
27894 /* All TYPE_PACK_EXPANSIONs are dependent, because parameter packs must
27895 be template parameters. */
27905 /* The standard does not specifically mention types that are local
27906 to template functions or local classes, but they should be
27907 considered dependent too. For example:
27909 template <int I> void f() {
27910 enum E { a = I };
27911 S<sizeof (E)> s;
27912 }
27914 The size of `E' cannot be known until the value of `I' has been
27915 determined. Therefore, `E' must be considered dependent. */
27919 /* Don't use type_dependent_expression_p here, as it can lead
27920 to infinite recursion trying to determine whether a lambda
27921 nested in a lambda is dependent (c++/47687). */
27925 && (any_dependent_template_arguments_p
27929 /* Other types are non-dependent. */
27931 }
27933 /* Returns TRUE if TYPE is dependent, in the sense of
27934 [temp.dep.type]. Note that a NULL type is considered dependent. */
27936 bool
27938 {
27939 /* If there are no template parameters in scope, then there can't be
27940 any dependent types. */
27942 {
27943 /* If we are not processing a template, then nobody should be
27944 providing us with a dependent type. */
27948 }
27950 /* If the type is NULL, we have not computed a type for the entity
27951 in question; in that case, the type is dependent. */
27955 /* Erroneous types can be considered non-dependent. */
27959 /* If we have not already computed the appropriate value for TYPE,
27960 do so now. */
27962 {
27965 }
27968 }
27970 /* Returns TRUE if SCOPE is a dependent scope, in which we can't do any
27971 lookup. In other words, a dependent type that is not the current
27972 instantiation. */
27974 bool
27976 {
27979 }
27981 /* True if we might find more declarations in SCOPE during instantiation than
27982 we can when parsing the template. */
27984 bool
27986 {
27988 }
27990 /* T is a SCOPE_REF. Return whether it represents a non-static member of
27991 an unknown base of 'this' (and is therefore instantiation-dependent). */
27993 static bool
27995 {
28012 }
28014 /* T is a SCOPE_REF; return whether we need to consider it
28015 instantiation-dependent so that we can check access at instantiation
28016 time even though we know which member it resolves to. */
28018 static bool
28020 {
28028 else
28030 }
28032 /* Returns TRUE if the EXPRESSION is value-dependent, in the sense of
28033 [temp.dep.constexpr]. EXPRESSION is already known to be a constant
28034 expression. */
28036 /* Note that this predicate is not appropriate for general expressions;
28037 only constant expressions (that satisfy potential_constant_expression)
28038 can be tested for value dependence. */
28040 bool
28042 {
28046 /* A type-dependent expression is also value-dependent. */
28051 {
28053 /* A dependent member function of the current instantiation. */
28057 /* A dependent member function of the current instantiation. */
28064 /* A name that has not been looked up -- must be dependent. */
28068 /* A non-type template parm. */
28072 /* A non-type template parm. */
28078 /* A constant with literal type and is initialized
28079 with an expression that is value-dependent. */
28083 {
28086 /* __PRETTY_FUNCTION__ inside a template function is dependent
28087 on the name of the function. */
28089 /* It might be used in a template, but not a template
28090 function, in which case its DECL_VALUE_EXPR will be
28091 "top level". */
28094 }
28096 /* FIXME cp_finish_decl doesn't fold reference initializers. */
28098 /* We have a constexpr variable and we're processing a template. When
28099 there's lifetime extension involved (for which finish_compound_literal
28100 used to create a temporary), we'll not be able to evaluate the
28101 variable until instantiating, so pretend it's value-dependent. */
28113 /* These expressions are value-dependent if the type to which
28114 the cast occurs is dependent or the expression being casted
28115 is value-dependent. */
28116 {
28122 /* A functional cast has a list of operands. */
28125 {
28126 /* If there are no operands, it must be an expression such
28127 as "int()". This should not happen for aggregate types
28128 because it would form non-constant expressions. */
28133 }
28143 }
28148 /* FALLTHRU */
28151 /* A `sizeof' expression is value-dependent if the operand is
28152 type-dependent or is a pack expansion. */
28161 /* An 'encode' expression is value-dependent if the operand is
28162 type-dependent. */
28171 /* All instantiation-dependent expressions should also be considered
28172 value-dependent. */
28180 /* A NONTYPE_ARGUMENT_PACK is value-dependent if any packed argument
28181 is value-dependent. */
28188 {
28204 }
28215 {
28219 }
28222 /* Treat all requires-expressions as value-dependent so
28223 we don't try to fold them. */
28230 {
28237 {
28239 /* In a call to a constexpr member function, look through the
28240 implicit ADDR_EXPR on the object argument so that it doesn't
28241 cause the call to be considered value-dependent. We also
28242 look through it in potential_constant_expression. */
28249 }
28251 }
28258 {
28260 tree val;
28267 }
28270 /* Treat a GNU statement expression as dependent to avoid crashing
28271 under instantiate_non_dependent_expr; it can't be constant. */
28276 /* The second operand is a type, which type_dependent_expression_p
28277 (and therefore value_dependent_expression_p) doesn't want to see. */
28283 /* A constant expression is value-dependent if any subexpression is
28284 value-dependent. */
28286 {
28293 {
28297 {
28300 /* In some cases, some of the operands may be missing.
28301 (For example, in the case of PREDECREMENT_EXPR, the
28302 amount to increment by may be missing.) That doesn't
28303 make the expression dependent. */
28306 }
28307 }
28311 }
28313 }
28315 /* The expression is not value-dependent. */
28317 }
28319 /* Returns TRUE if the EXPRESSION is type-dependent, in the sense of
28320 [temp.dep.expr]. Note that an expression with no type is
28321 considered dependent. Other parts of the compiler arrange for an
28322 expression with type-dependent subexpressions to have no type, so
28323 this function doesn't have to be fully recursive. */
28325 bool
28327 {
28338 /* An unresolved name is always dependent. */
28344 /* A lambda-expression in template context is dependent. dependent_type_p is
28345 true for a lambda in the scope of a class or function template, but that
28346 doesn't cover all template contexts, like a default template argument. */
28350 /* A fold expression is type-dependent. */
28357 /* Some expression forms are never type-dependent. */
28370 /* The types of these expressions depends only on the type to which
28371 the cast occurs. */
28380 /* The types of these expressions depends only on the type created
28381 by the expression. */
28384 {
28385 /* For NEW_EXPR tree nodes created inside a template, either
28386 the object type itself or a TREE_LIST may appear as the
28387 operand 1. */
28390 /* This is an array type. We need to check array dimensions
28391 as well. */
28393 || value_dependent_expression_p
28395 /* Array type whose dimension has to be deduced. */
28399 else
28401 }
28404 {
28408 /* 14.6.2.2 [temp.dep.expr]: An id-expression is type-dependent if it
28409 contains an identifier associated by name lookup with one or more
28410 declarations declared with a dependent type, or...a
28411 nested-name-specifier or qualified-id that names a member of an
28412 unknown specialization. */
28415 }
28425 {
28430 }
28432 /* A static data member of the current instantiation with incomplete
28433 array type is type-dependent, as the definition and specializations
28434 can have different bounds. */
28441 /* An array of unknown bound depending on a variadic parameter, eg:
28443 template<typename... Args>
28444 void foo (Args... args)
28445 {
28446 int arr[] = { args... };
28447 }
28449 template<int... vals>
28450 void bar ()
28451 {
28452 int arr[] = { vals... };
28453 }
28455 If the array has no length and has an initializer, it must be that
28456 we couldn't determine its length in cp_complete_array_type because
28457 it is dependent. */
28465 /* Pull a FUNCTION_DECL out of a BASELINK if we can. */
28467 {
28472 }
28474 /* A function or variable template-id is type-dependent if it has any
28475 dependent template arguments. */
28479 {
28480 /* Consider the innermost template arguments, since those are the ones
28481 that come from the template-id; the template arguments for the
28482 enclosing class do not make it type-dependent unless they are used in
28483 the type of the decl. */
28485 && (any_dependent_template_arguments_p
28488 }
28490 /* Otherwise, if the function decl isn't from a dependent scope, it can't be
28491 type-dependent. Checking this is important for functions with auto return
28492 type, which looks like a dependent type. */
28501 {
28505 }
28507 /* Otherwise, its constraints could still depend on outer template parameters
28508 from its (dependent) scope. */
28510 /* As an optimization, check this cheaper sufficient condition first.
28511 (At this point we've established that we're looking at a member of
28512 a dependent class, so it makes sense to start treating say undeduced
28513 auto as dependent.) */
28518 /* Always dependent, on the number of arguments if nothing else. */
28523 {
28528 {
28534 }
28535 /* SCOPE_REF with non-null TREE_TYPE is always non-dependent. */
28539 /* CO_AWAIT/YIELD_EXPR with unknown type is always dependent. */
28545 {
28550 }
28553 {
28560 }
28569 }
28571 /* The type of a non-type template parm declared with a placeholder type
28572 depends on the corresponding template argument, even though
28573 placeholders are not normally considered dependent. */
28580 /* Dependent type attributes might not have made it from the decl to
28581 the type yet. */
28587 }
28589 /* [temp.dep.expr]/5: A class member access expression (5.2.5) is
28590 type-dependent if the expression refers to a member of the current
28591 instantiation and the type of the referenced member is dependent, or the
28592 class member access expression refers to a member of an unknown
28593 specialization.
28595 This function returns true if the OBJECT in such a class member access
28596 expression is of an unknown specialization. */
28598 bool
28600 {
28601 /* An IDENTIFIER_NODE can sometimes have a TREE_TYPE, but it's still
28602 dependent. */
28607 }
28609 /* walk_tree callback function for instantiation_dependent_expression_p,
28610 below. Returns non-zero if a dependent subexpression is found. */
28612 static tree
28615 {
28617 {
28618 /* We don't have to worry about decltype currently because decltype
28619 of an instantiation-dependent expr is a dependent type. This
28620 might change depending on the resolution of DR 1172. */
28623 }
28626 {
28627 /* Don't treat an argument list as dependent just because it has no
28628 TREE_TYPE. */
28639 /* We'll check value-dependence separately. */
28642 /* Handle expressions with type operands. */
28647 {
28652 {
28655 else
28656 {
28659 }
28660 }
28662 }
28666 /* In a template, finish_class_member_access_expr creates a
28667 COMPONENT_REF with an IDENTIFIER_NODE for op1 even if it isn't
28668 type-dependent, so that we can check access control at
28669 instantiation time (PR 42277). See also Core issue 1273. */
28676 else
28679 /* Treat statement-expressions as dependent. */
28683 /* Treat requires-expressions as dependent. */
28694 /* Before C++17, a noexcept-specifier isn't part of the function type
28695 so it doesn't affect type dependence, but we still want to consider it
28696 for instantiation dependence. */
28705 }
28709 else
28711 }
28713 /* Returns TRUE if the EXPRESSION is instantiation-dependent, in the
28714 sense defined by the ABI:
28716 "An expression is instantiation-dependent if it is type-dependent
28717 or value-dependent, or it has a subexpression that is type-dependent
28718 or value-dependent."
28720 Except don't actually check value-dependence for unevaluated expressions,
28721 because in sizeof(i) we don't care about the value of i. Checking
28722 type-dependence will in turn check value-dependence of array bounds/template
28723 arguments as needed. */
28725 bool
28727 {
28728 tree result;
28739 }
28741 /* As above, but also check value-dependence of the expression as a whole. */
28743 bool
28745 {
28747 || (processing_template_decl
28750 }
28752 /* Like type_dependent_expression_p, but it also works while not processing
28753 a template definition, i.e. during substitution or mangling. */
28755 bool
28757 {
28763 }
28765 /* Returns TRUE if ARGS contains a type-dependent expression. */
28767 bool
28769 {
28778 }
28780 /* Returns TRUE if LIST (a TREE_LIST whose TREE_VALUEs are
28781 expressions) contains any type-dependent expressions. */
28783 bool
28785 {
28791 }
28793 /* Returns TRUE if LIST (a TREE_LIST whose TREE_VALUEs are
28794 expressions) contains any value-dependent expressions. */
28796 bool
28798 {
28804 }
28806 /* Returns TRUE if the ARG (a template argument) is dependent. */
28808 bool
28810 {
28814 /* Assume a template argument that was wrongly written by the user
28815 is dependent. This is consistent with what
28816 any_dependent_template_arguments_p [that calls this function]
28817 does. */
28827 {
28830 /* A member template of a dependent class is not necessarily
28831 type-dependent, but it is a dependent template argument because it
28832 will be a member of an unknown specialization to that template. */
28835 }
28837 {
28843 }
28846 else
28848 }
28850 /* Identify any expressions that use function parms. */
28852 static tree
28854 {
28857 {
28860 }
28862 }
28864 /* Returns true if a type specialization formed using the template
28865 arguments ARGS needs to use structural equality. */
28867 bool
28869 {
28879 {
28882 {
28888 {
28889 /* Look inside the argument pack. */
28892 }
28895 {
28904 /* An any_targ_node argument (added by add_defaults_to_ttp)
28905 makes the corresponding specialization not canonicalizable,
28906 since template_args_equal always return true for it. We
28907 may see this when called from bind_template_template_parm. */
28909 /* Checking current_function_decl because this structural
28910 comparison is only necessary for redeclaration. */
28913 && (cp_walk_tree_without_duplicates
28915 /* The identity of a class template specialization that uses
28916 a function parameter depends on the identity of the function.
28917 And if this specialization appeared in the trailing return
28918 type thereof, we don't know the identity of the function
28919 (e.g. if it's a redeclaration or a new function) until we
28920 form its signature and go through duplicate_decls. Thus
28921 it's unsafe to decide on a canonical type now (which depends
28922 on the DECL_CONTEXT of the function parameter, which can get
28923 mutated after the fact by duplicate_decls), so just require
28924 structural equality in this case (PR52830). */
28929 /* Require structural equality for specializations written
28930 in terms of a dependent alias template specialization. */
28935 /* Require structural equality for specializations written
28936 in terms of a class template specialization that itself
28937 needs structural equality. */
28939 }
28940 }
28941 }
28944 }
28946 /* Returns true if ARGS (a collection of template arguments) contains
28947 any dependent arguments. */
28949 bool
28951 {
28958 {
28963 }
28966 }
28968 /* Returns true if ARGS contains any errors. */
28970 bool
28972 {
28980 {
28983 else
28985 }
28991 {
28996 }
28999 }
29001 /* Returns TRUE if the template TMPL is type-dependent. */
29003 bool
29005 {
29007 {
29012 }
29014 /* Template template parameters are dependent. */
29018 /* So are names that have not been looked up. */
29022 }
29024 /* Returns TRUE if the specialization TMPL<ARGS> is dependent. */
29026 bool
29028 {
29031 }
29033 /* Returns TRUE if OMP_FOR with DECLV, INITV, CONDV and INCRV vectors
29034 are dependent. */
29036 bool
29038 {
29045 {
29070 {
29074 }
29078 {
29082 {
29088 /* If this loop has a class iterator with != comparison
29089 with increment other than i++/++i/i--/--i, make sure the
29090 increment is constant. */
29093 {
29096 else
29100 }
29101 }
29102 }
29103 }
29106 }
29108 /* TYPE is a TYPENAME_TYPE. Returns the ordinary TYPE to which the
29109 TYPENAME_TYPE corresponds. Returns the original TYPENAME_TYPE if
29110 no such TYPE can be found. Note that this function peers inside
29111 uninstantiated templates and therefore should be used only in
29112 extremely limited situations. ONLY_CURRENT_P restricts this
29113 peering to the currently open classes hierarchy (which is required
29114 when comparing types). */
29116 tree
29118 {
29119 tree scope;
29120 tree name;
29121 tree decl;
29123 tree pushed_scope;
29124 tree result;
29129 /* We shouldn't have built a TYPENAME_TYPE with a non-dependent scope. */
29132 /* Usually the non-qualified identifier of a TYPENAME_TYPE is
29133 TYPE_IDENTIFIER (type). But when 'type' is a typedef variant of a
29134 TYPENAME_TYPE node, then TYPE_NAME (type) is set to the TYPE_DECL
29135 representing the typedef. In that case TYPE_IDENTIFIER (type) is
29136 not the non-qualified identifier of the TYPENAME_TYPE anymore.
29137 So by getting the TYPE_IDENTIFIER of the _main declaration_ of
29138 the TYPENAME_TYPE instead, we avoid messing up with a possible
29139 typedef variant case. */
29142 /* If the SCOPE is itself a TYPENAME_TYPE, then we need to resolve
29143 it first before we can figure out what NAME refers to. */
29145 {
29147 /* Given a class template A with a dependent base with nested type C,
29148 typedef typename A::C::C C will land us here, as trying to resolve
29149 the initial A::C leads to the local C typedef, which leads back to
29150 A::C::C. So we break the recursion now. */
29152 else
29154 }
29155 /* If we don't know what SCOPE refers to, then we cannot resolve the
29156 TYPENAME_TYPE. */
29159 /* If this is a typedef, we don't want to look inside (c++/11987). */
29162 /* If SCOPE isn't the template itself, it will not have a valid
29163 TYPE_FIELDS list. */
29165 /* scope is either the template itself or a compatible instantiation
29166 like X<T>, so look up the name in the original template. */
29168 /* If scope has no fields, it can't be a current instantiation. Check this
29169 before currently_open_class to avoid infinite recursion (71515). */
29172 /* If the SCOPE is not the current instantiation, there's no reason
29173 to look inside it. */
29176 /* Enter the SCOPE so that name lookup will be resolved as if we
29177 were in the class definition. In particular, SCOPE will no
29178 longer be considered a dependent type. */
29180 /* Look up the declaration. */
29182 tf_warning_or_error);
29186 /* For a TYPENAME_TYPE like "typename X::template Y<T>", we want to
29187 find a TEMPLATE_DECL. Otherwise, we want to find a TYPE_DECL. */
29193 {
29197 }
29200 {
29201 /* Obtain the template and the arguments. */
29204 {
29205 /* We get here with a plain identifier because a previous tentative
29206 parse of the nested-name-specifier as part of a ptr-operator saw
29207 ::template X<A>. The use of ::template is necessary in a
29208 ptr-operator, but wrong in a declarator-id.
29210 [temp.names]: In a qualified-id of a declarator-id, the keyword
29211 template shall not appear at the top level. */
29215 }
29217 /* Instantiate the template. */
29223 }
29225 /* Leave the SCOPE. */
29229 /* If we failed to resolve it, return the original typename. */
29233 /* If lookup found a typename type, resolve that too. */
29235 {
29236 /* Ill-formed programs can cause infinite recursion here, so we
29237 must catch that. */
29241 }
29243 /* Qualify the resulting type. */
29249 }
29251 /* Returns a type which represents 'auto' or 'decltype(auto)'. We use a
29252 TEMPLATE_TYPE_PARM with a level one deeper than the actual template parms,
29253 by default. If set_canonical is true, we set TYPE_CANONICAL on it. */
29255 static tree
29257 {
29273 }
29275 tree
29277 {
29279 }
29281 tree
29283 {
29285 }
29287 /* Return a C++17 deduction placeholder for class template TMPL.
29288 There are represented as an 'auto' with the special level 0 and
29289 CLASS_PLACEHOLDER_TEMPLATE set. */
29291 tree
29293 {
29296 /* Our canonical type depends on the placeholder. */
29299 }
29301 /* True iff T is a C++17 class template deduction placeholder. */
29303 bool
29305 {
29307 }
29309 /* Make a "constrained auto" type-specifier. This is an auto or
29310 decltype(auto) type with constraints that must be associated after
29311 deduction. The constraint is formed from the given concept CON
29312 and its optional sequence of template arguments ARGS.
29314 TYPE must be the result of make_auto_type or make_decltype_auto_type. */
29316 static tree
29318 {
29319 /* Build the constraint. */
29331 /* Our canonical type depends on the constraint. */
29334 /* Attach the constraint to the type declaration. */
29336 }
29338 /* Make a "constrained auto" type-specifier. */
29340 tree
29342 {
29345 }
29347 /* Make a "constrained decltype(auto)" type-specifier. */
29349 tree
29351 {
29354 }
29356 /* Returns true if the placeholder type constraint T has any dependent
29357 (explicit) template arguments. */
29359 static bool
29361 {
29366 {
29369 }
29376 }
29378 /* Build and return a concept definition. Like other templates, the
29379 CONCEPT_DECL node is wrapped by a TEMPLATE_DECL. This returns the
29380 the TEMPLATE_DECL. */
29382 tree
29384 {
29390 /* A concept-definition shall not have associated constraints. */
29392 {
29395 }
29397 /* A concept-definition shall appear in namespace scope. Templates
29398 aren't allowed in block scope, so we only need to check for class
29399 scope. */
29401 {
29404 }
29407 {
29410 }
29412 /* Initially build the concept declaration; its type is bool. */
29422 /* Push the enclosing template. */
29424 }
29426 /* Given type ARG, return std::initializer_list<ARG>. */
29428 static tree
29430 {
29435 {
29439 "deducing from brace-enclosed initializer list"
29443 }
29449 }
29451 /* Replace auto in TYPE with std::initializer_list<auto>. */
29453 static tree
29455 {
29462 }
29464 /* Hash traits for hashing possibly constrained 'auto'
29465 TEMPLATE_TYPE_PARMs for use by do_auto_deduction. */
29468 {
29471 };
29473 /* Hash the 'auto' T. */
29475 inline hashval_t
29477 {
29479 /* Matching constrained-type-specifiers denote the same template
29480 parameter, so hash the constraint. */
29482 else
29483 /* But unconstrained autos are all separate, so just hash the pointer. */
29485 }
29487 /* Compare two 'auto's. */
29491 {
29498 /* Two unconstrained autos are distinct. */
29503 }
29505 /* for_each_template_parm callback for extract_autos: if t is a (possibly
29506 constrained) auto, add it to the vector. */
29508 static int
29510 {
29513 {
29514 /* All the autos were built with index 0; fix that up now. */
29518 /* If this is a repeated constrained-type-specifier, use the index we
29519 chose before. */
29521 else
29522 {
29523 /* Otherwise this is new, so use the current count. */
29526 }
29528 {
29533 }
29534 }
29536 /* Always keep walking. */
29538 }
29540 /* Return a TREE_VEC of the 'auto's used in type under the Concepts TS, which
29541 says they can appear anywhere in the type. */
29543 static tree
29545 {
29553 {
29557 }
29560 }
29562 /* The stem for deduction guide names. */
29565 /* Return the name for a deduction guide for class template TMPL. */
29567 tree
29569 {
29580 }
29582 /* True if NAME is the name of a deduction guide. */
29584 bool
29586 {
29590 }
29592 /* True if FN is a deduction guide. */
29594 bool
29596 {
29601 }
29603 /* True if FN is the copy deduction guide, i.e. A(A)->A. */
29605 bool
29607 {
29614 }
29616 /* True if FN is a guide generated from a constructor template. */
29618 bool
29620 {
29628 }
29630 /* True if FN is an aggregate initialization guide or the copy deduction
29631 guide. */
29633 bool
29635 {
29639 /* Explicitly declared. */
29642 /* Derived from a constructor. */
29645 }
29647 /* OLDDECL is a _DECL for a template parameter. Return a similar parameter at
29648 LEVEL:INDEX, using tsubst_args and complain for substitution into non-type
29649 template parameter types. Note that the handling of template template
29650 parameters relies on current_template_parms being set appropriately for the
29651 new template. */
29653 static tree
29656 {
29662 tree newtype;
29665 {
29669 }
29670 else
29671 {
29674 {
29675 // Substitute once to fix references to other template parameters.
29678 // Now substitute again to reduce the level of the auto.
29681 }
29682 else
29685 }
29687 tree newdecl
29692 tree newidx;
29695 {
29704 {
29705 tree newresult
29710 // First create a copy (ttargs) of tsubst_args with an
29711 // additional level for the template template parameter's own
29712 // template parameters (ttparms).
29713 tree ttparms = (INNERMOST_TEMPLATE_PARMS
29721 // Substitute ttargs into ttparms to fix references to
29722 // other template parameters.
29725 // Now substitute again with args based on tparms, to reduce
29726 // the level of the ttparms.
29729 complain);
29730 // Finally, tack the adjusted parms onto tparms.
29733 // As with all template template parms, the parameter list captured
29734 // by this template template parm that corresponds to its own level
29735 // should be empty. This avoids infinite recursion when structurally
29736 // comparing two such rewritten template template parms (PR102479).
29741 // All done.
29745 }
29749 else
29751 }
29752 else
29753 {
29755 tree newconst
29767 }
29770 }
29772 /* As rewrite_template_parm, but for the whole TREE_LIST representing a
29773 template parameter. */
29775 static tree
29778 {
29793 }
29795 /* Returns a C++17 class deduction guide template based on the constructor
29796 CTOR. As a special case, CTOR can be a RECORD_TYPE for an implicit default
29797 guide, REFERENCE_TYPE for an implicit copy/move guide, or TREE_LIST for an
29798 aggregate initialization guide. OUTER_ARGS are the template arguments
29799 for the enclosing scope of the class. */
29801 static tree
29803 {
29807 location_t loc;
29811 {
29815 }
29818 {
29820 {
29824 else
29826 }
29829 else
29839 }
29840 else
29841 {
29847 fn_tmpl
29855 /* If type is a member class template, DECL_TI_ARGS (ctor) will have
29856 fully specialized args for the enclosing class. Strip those off, as
29857 the deduction guide won't have those template parameters. */
29860 /* Discard the 'this' parameter. */
29868 {
29871 /* For a member template constructor, we need to flatten the two
29872 template parameter lists into one, and then adjust the function
29873 signature accordingly. This gets...complicated. */
29876 /* For a member template we should have two levels of parms/args, one
29877 for the class and one for the constructor. We stripped
29878 specialized args for further enclosing classes above. */
29882 /* Template args for translating references to the two-level template
29883 parameters into references to the one-level template parameters we
29884 are creating. */
29889 /* Template parms for the constructor template. */
29892 /* Template parms for the class template. */
29896 /* Template parms for the deduction guide start as a copy of the
29897 template parms for the class. We set current_template_parms for
29898 lookup_template_class_1. */
29904 /* Now we need to rewrite the constructor parms to append them to the
29905 class parms. */
29907 {
29911 tree newelt
29917 }
29919 /* Now we have a final set of template parms to substitute into the
29920 function signature. */
29927 {
29929 /* FIXME: We'd like to avoid substituting outer template
29930 arguments into the constraint ahead of time, but the
29931 construction of tsubst_args assumes that outer arguments
29932 are already substituted in. */
29935 }
29937 /* Parms are to have DECL_CHAIN tsubsted, which would be skipped if
29938 cp_unevaluated_operand. */
29939 cp_evaluated ev;
29942 }
29943 else
29944 {
29945 /* Substitute in the same arguments to rewrite class members into
29946 references to members of an unknown specialization. */
29947 cp_evaluated ev;
29951 {
29953 /* FIXME: As above. */
29956 }
29957 }
29962 }
29965 {
29966 /* Copy the parms so we can set DECL_PRIMARY_TEMPLATE. */
29970 }
29974 FUNCTION_DECL,
29989 }
29991 /* Add to LIST the member types for the reshaped initializer CTOR. */
29993 static tree
29995 {
29999 {
30003 {
30009 }
30013 /* Give the trailing pack expansion parameter a default argument to
30014 match aggregate initialization behavior, even if we deduce the
30015 length of the pack separately to more than we have initializers. */
30017 /* if ei is of array type and xi is a braced-init-list or string literal,
30018 Ti is an rvalue reference to the declared type of ei */
30023 {
30025 ftype = cp_build_qualified_type
30027 ftype = (cp_build_reference_type
30029 }
30031 }
30034 }
30036 /* Return whether ETYPE is, or is derived from, a specialization of TMPL. */
30038 static bool
30040 {
30046 tree tparms = (INNERMOST_TEMPLATE_PARMS
30053 }
30055 /* Return a C++20 aggregate deduction candidate for TYPE initialized from
30056 INIT. */
30058 static tree
30060 {
30068 {
30074 }
30076 /* We might be creating a guide for a class member template, e.g.,
30078 template<typename U> struct A {
30079 template<typename T> struct B { T t; };
30080 };
30082 At this point, A will have been instantiated. Below, we need to
30083 use both A<U>::B<T> (TEMPLATE_TYPE) and A<int>::B<T> (TYPE) types. */
30084 const bool member_template_p
30088 tree template_type = (member_template_p
30094 /* No aggregate candidate for copy-initialization. */
30096 {
30100 }
30102 /* If we encounter a problem, we just won't add the candidate. */
30107 {
30112 /* If we're creating a deduction guide for a member class template,
30113 we've used the original template pattern type for the reshape_init
30114 above; this is done because we want PARMS to be a template parameter
30115 type, something that can be deduced when used as a function template
30116 parameter. At this point the outer class template has already been
30117 partially instantiated (we deferred the deduction until the enclosing
30118 scope is non-dependent). Therefore we have to partially instantiate
30119 PARMS, so that its template level is properly reduced and we don't get
30120 mismatches when deducing types using the guide with PARMS. */
30122 {
30126 }
30127 }
30129 {
30132 len;
30134 {
30140 }
30141 }
30142 else
30143 /* Aggregate initialization doesn't apply to an initializer expression. */
30147 {
30153 }
30156 }
30158 /* UGUIDES are the deduction guides for the underlying template of alias
30159 template TMPL; adjust them to be deduction guides for TMPL.
30161 This routine also handles C++23 inherited CTAD, in which case TMPL is a
30162 TREE_LIST representing a synthetic alias template whose TREE_PURPOSE is
30163 the template parameter list of the alias template (equivalently, of the
30164 derived class) and TREE_VALUE the defining-type-id (equivalently, the
30165 base whose guides we're inheriting). UGUIDES are the base's guides. */
30167 static tree
30169 {
30170 /* [over.match.class.deduct]: When resolving a placeholder for a deduced
30171 class type (9.2.8.2) where the template-name names an alias template A,
30172 the defining-type-id of A must be of the form
30174 typename(opt) nested-name-specifier(opt) template(opt) simple-template-id
30176 as specified in 9.2.8.2. The guides of A are the set of functions or
30177 function templates formed as follows. For each function or function
30178 template f in the guides of the template named by the simple-template-id
30179 of the defining-type-id, the template arguments of the return type of f
30180 are deduced from the defining-type-id of A according to the process in
30181 13.10.2.5 with the exception that deduction does not fail if not all
30182 template arguments are deduced. Let g denote the result of substituting
30183 these deductions into f. If substitution succeeds, form a function or
30184 function template f' with the following properties and add it to the set
30185 of guides of A:
30187 * The function type of f' is the function type of g.
30189 * If f is a function template, f' is a function template whose template
30190 parameter list consists of all the template parameters of A (including
30191 their default template arguments) that appear in the above deductions or
30192 (recursively) in their default template arguments, followed by the
30193 template parameters of f that were not deduced (including their default
30194 template arguments), otherwise f' is not a function template.
30196 * The associated constraints (13.5.2) are the conjunction of the
30197 associated constraints of g and a constraint that is satisfied if and only
30198 if the arguments of A are deducible (see below) from the return type.
30200 * If f is a copy deduction candidate (12.4.1.8), then f' is considered to
30201 be so as well.
30203 * If f was generated from a deduction-guide (12.4.1.8), then f' is
30204 considered to be so as well.
30206 * The explicit-specifier of f' is the explicit-specifier of g (if
30207 any). */
30212 {
30217 }
30218 else
30219 {
30224 }
30231 {
30238 {
30242 /* Deduce template arguments for f from the type-id of A. */
30248 /* CWG2664: Discard any deductions, still build the guide. */
30252 /* The number of parms for f' is the number of parms of A used in
30253 the deduced arguments plus non-deduced parms of f. */
30265 /* Set current_template_parms as in build_deduction_guide. */
30273 /* First copy over the used parms of A. */
30276 {
30279 {
30284 }
30285 }
30288 /* Adjust the deduced template args for f to refer to the A parms
30289 with their new indexes. */
30293 /* Now rewrite the non-deduced parms of f. */
30296 {
30303 }
30306 /* Substitute the deduced arguments plus the rewritten template
30307 parameters into f to get g. This covers the type, copyness,
30308 guideness, and explicit-specifier. */
30309 tree g;
30310 {
30311 /* Parms are to have DECL_CHAIN tsubsted, which would be skipped
30312 if cp_unevaluated_operand. */
30313 cp_evaluated ev;
30316 }
30320 {
30321 /* The targs are all non-dependent, so g isn't a template. */
30325 }
30334 /* Substitute the associated constraints. */
30341 /* Add a constraint that the return type matches the instantiation of
30342 A with the same template arguments. */
30346 /* FIXME this should mean they don't compare as equivalent. */
30348 {
30351 }
30354 {
30357 }
30358 }
30359 else
30360 {
30361 /* For a non-template deduction guide, if the arguments of A aren't
30362 deducible from the return type, don't add the candidate. */
30363 non_template:
30367 }
30369 /* Rewrite the return type of the inherited guide in terms of the
30370 derived class. This is specified as replacing the return type R
30371 with typename CC<R>::type where the partially specialized CC maps a
30372 base class specialization to a specialization of the derived class
30373 having such a base (inducing substitution failure if no such derived
30374 class exists).
30376 As specified this mapping would be done at instantiation time using
30377 non-dependent template arguments, but we do it ahead of time using
30378 the generic arguments. This seems to be good enough since generic
30379 deduction should succeed only if concrete deduction would. */
30381 {
30399 }
30402 }
30405 }
30407 /* CTOR is a using-decl inheriting the constructors of some base of the class
30408 template TMPL; adjust the base's guides be deduction guides for TMPL. */
30410 static tree
30412 {
30413 /* [over.match.class.deduct]: In addition, if C is defined and inherits
30414 constructors ([namespace.udecl]) from a direct base class denoted in the
30415 base-specifier-list by a class-or-decltype B, let A be an alias template
30416 whose template parameter list is that of C and whose defining-type-id is
30417 B. If A is a deducible template ([dcl.type.simple]), the set contains the
30418 guides of A with the return type R of each guide replaced with typename
30419 CC::type given a class template
30421 template <typename> class CC;
30423 whose primary template is not defined and with a single partial
30424 specialization whose template parameter list is that of A and whose
30425 template argument list is a specialization of A with the template argument
30426 list of A ([temp.dep.type]) having a member typedef type designating a
30427 template specialization with the template argument list of A but with C as
30428 the template. */
30430 /* FIXME: Also recognize inherited constructors of the form 'using C::B::B',
30431 which seem to be represented with TYPENAME_TYPE C::B as USING_DECL_SCOPE?
30432 And recognize constructors inherited from a non-dependent base class, which
30433 seem to be missing from the overload set entirely? */
30445 }
30447 /* If template arguments for TMPL can be deduced from TYPE, return
30448 the deduced arguments, otherwise return NULL_TREE.
30449 Used to implement CPTK_IS_DEDUCIBLE for alias CTAD according to
30450 [over.match.class.deduct].
30452 This check is specified in terms of partial specialization, so the behavior
30453 should be parallel to that of get_partial_spec_bindings. */
30455 tree
30457 {
30460 {
30461 /* If tmpl is a class template, this is trivial: it's deducible if
30462 TYPE is a specialization of TMPL. */
30464 {
30469 else
30471 }
30473 /* Otherwise it's an alias template. */
30476 }
30477 else
30478 {
30479 /* TMPL is a synthetic alias template represented as a TREE_LIST as
30480 per alias_ctad_tweaks. */
30484 }
30490 again:
30495 /* We don't fail on an undeduced targ the second time through (like
30496 get_partial_spec_bindings) because we're going to try defaults. */
30499 {
30505 {
30510 }
30511 /* If the type parameter is a parameter pack, then it will be deduced
30512 to an empty parameter pack. This is another case that doesn't model
30513 well as partial specialization. */
30515 {
30516 tree arg;
30518 {
30521 }
30522 else
30526 }
30527 }
30529 /* Maybe add in default template args. This seems like a flaw in the
30530 specification in terms of partial specialization, since it says the
30531 partial specialization has the the template parameter list of A, but a
30532 partial specialization can't have default targs. */
30537 /* I believe we don't need the template_template_parm_bindings_ok_p call
30538 because coerce_template_parms did coerce_template_template_parms. */
30544 }
30546 /* Return artificial deduction guides built from the constructors of class
30547 template TMPL. */
30549 static tree
30551 {
30558 {
30559 /* We handle C++23 inherited CTAD below. */
30565 }
30570 {
30574 }
30576 /* Add implicit default constructor deduction guide. */
30578 {
30580 complain);
30582 }
30584 /* Add copy guide. */
30585 {
30588 complain);
30590 }
30593 }
30597 /* Return the non-aggregate deduction guides for deducible template TMPL. The
30598 aggregate candidate is added separately because it depends on the
30599 initializer. Set ANY_DGUIDES_P if we find a non-implicit deduction
30600 guide. */
30602 static tree
30604 {
30607 {
30611 complain);
30612 }
30613 else
30614 {
30620 else
30622 }
30624 /* Cache the deduction guides for a template. We also remember the result of
30625 lookup, and rebuild everything if it changes; should be very rare. */
30626 /* FIXME: Also rebuild if this is a class template that inherits guides from a
30627 base class, and lookup for the latter changed. */
30631 {
30635 }
30636 else
30637 {
30640 }
30645 else
30646 {
30650 }
30654 }
30656 /* Return whether TMPL is a (class template argument-) deducible template. */
30658 bool
30660 {
30661 /* A deducible template is either a class template or is an alias template
30662 whose defining-type-id is of the form
30664 typename(opt) nested-name-specifier(opt) template(opt) simple-template-id
30666 where the nested-name-specifier (if any) is non-dependent and the
30667 template-name of the simple-template-id names a deducible template. */
30678 }
30680 /* Deduce template arguments for the class template placeholder PTYPE for
30681 template TMPL based on the initializer INIT, and return the resulting
30682 type. */
30684 static tree
30687 {
30688 /* We should have handled this in the caller. */
30692 /* If the class was erroneous, don't try to deduce, because that
30693 can generate a lot of diagnostic. */
30699 /* Wait until the enclosing scope is non-dependent. */
30704 /* Initializing one placeholder from another. */
30715 {
30719 }
30721 {
30723 {
30724 /* Be permissive with equivalent alias templates. */
30727 bool complained
30729 "alias template deduction only available "
30734 {
30737 }
30738 }
30739 else
30741 }
30743 /* Wait until the initializer is non-dependent. */
30748 {
30752 {
30753 /* Substitute outer arguments into this CTAD template from the
30754 current instantiation. */
30761 }
30762 }
30764 /* Don't bother with the alias rules for an equivalent template. */
30777 {
30782 {
30783 /* As an exception, the first phase in 16.3.1.7 (considering the
30784 initializer list as a single argument) is omitted if the
30785 initializer list consists of a single expression of type cv U,
30786 where U is a specialization of C or a class derived from a
30787 specialization of C. */
30791 }
30794 else
30796 }
30799 else
30802 /* Do this now to avoid problems with erroneous args later on. */
30812 /* Prune explicit deduction guides in copy-initialization context (but
30813 not copy-list-initialization). */
30816 {
30822 {
30823 /* Found a nonconverting guide, prune the candidates. */
30830 }
30831 }
30839 /* If this is list-initialization and the class has a list guide, first
30840 try deducing from the list as a single argument, as [over.match.list]. */
30842 {
30850 {
30851 /* That didn't work, now try treating the list as a sequence of
30852 arguments. */
30858 }
30859 }
30862 {
30864 " of %qT, as it has no non-explicit deduction guides or "
30867 }
30869 {
30873 }
30879 {
30881 {
30887 }
30889 }
30890 /* [over.match.list]/1: In copy-list-initialization, if an explicit
30891 constructor is chosen, the initialization is ill-formed. */
30893 {
30895 {
30897 {
30898 // TODO: Pass down location from cp_finish_decl.
30900 "explicit deduction guide selected in "
30905 }
30907 }
30908 }
30910 /* If CTAD succeeded but the type doesn't have any explicit deduction
30911 guides, this deduction might not be what the user intended. */
30913 {
30917 "%qT may not intend to support class template argument "
30921 }
30925 }
30927 /* Return true if INIT is an unparenthesized id-expression or an
30928 unparenthesized class member access. Used for the argument of
30929 decltype(auto). */
30931 bool
30933 {
30936 /* We need to be able to tell '(r)' and 'r' apart (when it's of
30937 reference type). Only the latter is an id-expression. */
30945 }
30947 /* Replace occurrences of 'auto' in TYPE with the appropriate type deduced
30948 from INIT. AUTO_NODE is the TEMPLATE_TYPE_PARM used for 'auto' in TYPE.
30949 The CONTEXT determines the context in which auto deduction is performed
30950 and is used to control error diagnostics. FLAGS are the LOOKUP_* flags.
30952 OUTER_TARGS is used during template argument deduction (context == adc_unify)
30953 to properly substitute the result. It's also used in the adc_unify and
30954 adc_requirement contexts to communicate the necessary template arguments
30955 to satisfaction. OUTER_TARGS is ignored in other contexts.
30957 Additionally for adc_unify contexts TMPL is the template for which TYPE
30958 is a template parameter type.
30960 For partial-concept-ids, extra args from OUTER_TARGS, TMPL and the current
30961 scope may be appended to the list of deduced template arguments prior to
30962 determining constraint satisfaction as appropriate. */
30964 tree
30971 {
30977 /* Defining a subset of type-dependent expressions that we can deduce
30978 from ahead of time isn't worth the trouble. */
30981 /* Similarly, we can't deduce from another undeduced decl. */
30985 /* We may be doing a partial substitution, but we still want to replace
30986 auto_node. */
30990 {
30991 /* We don't recurse here because we can't deduce from a nested
30992 initializer_list. */
30996 }
31000 /* In C++23, we must deduce the type to int&& for code like
31001 decltype(auto) f(int&& x) { return (x); }
31002 or
31003 auto&& f(int x) { return x; }
31004 so we use treat_lvalue_as_rvalue_p. But don't do it for
31005 decltype(auto) f(int x) { return x; }
31006 where we should deduce 'int' rather than 'int&&'; transmogrifying
31007 INIT to an rvalue would break that. */
31008 tree r;
31018 /* C++17 class template argument deduction. */
31022 /* Nothing we can do with this, even in deduction context. */
31027 /* [dcl.spec.auto]: Obtain P from T by replacing the occurrences of auto
31028 with either a new invented type template parameter U or, if the
31029 initializer is a braced-init-list (8.5.4), with
31030 std::initializer_list<U>. */
31032 {
31037 else
31038 {
31040 {
31044 "for deduction to %<std::initializer_list%>, use copy-"
31046 }
31048 }
31049 }
31054 tree targs;
31058 {
31059 /* [dcl.struct.bind]/1 - if decomposition declaration has no ref-qualifiers
31060 and initializer has array type, deduce cv-qualified array type. */
31063 }
31065 {
31073 }
31074 else
31075 {
31080 tree tparms;
31084 else
31085 {
31089 }
31093 DEDUCE_CALL,
31096 {
31098 /* Try again at instantiation time. */
31102 /* If type is error_mark_node a diagnostic must have been
31103 emitted by now. Also, having a mention to '<type error>'
31104 in the diagnostic is not really useful to the user. */
31105 {
31108 && (auto_node
31112 init);
31113 else
31116 DEDUCE_CALL,
31118 }
31120 }
31121 }
31123 /* Check any placeholder constraints against the deduced type. */
31127 {
31129 {
31134 /* If the constraint is dependent, we need to wait until
31135 instantiation time to resolve the placeholder. */
31138 }
31145 {
31149 {
31150 /* As in satisfy_declaration_constraints. */
31154 else
31156 }
31157 }
31164 /* HACK: Compensate for callers not always communicating all levels of
31165 outer template arguments by filling in the outermost missing levels
31166 with dummy levels before checking satisfaction. We'll still crash
31167 if the constraint depends on a template argument belonging to one of
31168 these missing levels, but this hack otherwise allows us to handle a
31169 large subset of possible constraints (including all non-dependent
31170 constraints). */
31173 {
31178 }
31181 {
31183 {
31184 auto_diagnostic_group d;
31186 {
31204 }
31206 }
31208 }
31209 }
31212 /* The outer template arguments are already substituted into type
31219 }
31221 /* Substitutes LATE_RETURN_TYPE for 'auto' in TYPE and returns the
31222 result. */
31224 tree
31226 {
31228 {
31231 }
31235 {
31236 /* In an abbreviated function template we didn't know we were dealing
31237 with a function template when we saw the auto return type, so rebuild
31238 the return type using an auto with the correct level. */
31243 auto_vec);
31244 /* Also rebuild the constraint info in terms of the new auto. */
31252 }
31254 }
31256 /* Returns true iff TYPE is a TEMPLATE_TYPE_PARM representing 'auto' or
31257 'decltype(auto)' or a deduced class template. */
31259 bool
31261 {
31266 else
31268 }
31270 /* for_each_template_parm callback for type_uses_auto. */
31272 int
31274 {
31276 }
31278 /* Returns the TEMPLATE_TYPE_PARM in TYPE representing `auto' iff TYPE contains
31279 a use of `auto'. Returns NULL_TREE otherwise. */
31281 tree
31283 {
31287 /* For parameter packs, check the contents of the pack. */
31292 {
31293 /* The Concepts TS allows multiple autos in one type-specifier; just
31294 return the first one we find, do_auto_deduction will collect all of
31295 them. */
31299 else
31301 }
31302 else
31304 }
31306 /* Report ill-formed occurrences of auto types in ARGUMENTS. If
31307 concepts are enabled, auto is acceptable in template arguments, but
31308 only when TEMPL identifies a template class. Return TRUE if any
31309 such errors were reported. */
31311 bool
31313 {
31315 /* Only the concepts TS allows 'auto' as a type-id; it'd otherwise
31316 have already been rejected by the parser more generally. */
31319 /* If there were previous errors, nevermind. */
31323 /* If TMPL is an identifier, we're parsing and we can't tell yet
31324 whether TMPL is supposed to be a type, a function or a variable.
31325 We'll only be able to tell during template substitution, so we
31326 expect to be called again then. If concepts are enabled and we
31327 know we have a type, we're ok. */
31334 /* Quickly search for any occurrences of auto; usually there won't
31335 be any, and then we'll avoid allocating the vector. */
31343 {
31348 }
31351 }
31353 /* Recursively walk over && expressions searching for EXPR. Return a reference
31354 to that expression. */
31357 {
31361 {
31366 }
31368 }
31370 /* Convert the generic type parameters in PARM that match the types given in the
31371 range [START_IDX, END_IDX) from the current_template_parms into generic type
31372 packs. */
31374 tree
31376 {
31387 {
31388 /* Create a distinct parameter pack type from the current parm and add it
31389 to the replacement args to tsubst below into the generic function
31390 parameter. */
31404 /* Replace the current template parameter with new pack. */
31407 /* Surgically adjust the associated constraint of adjusted parameter
31408 and it's corresponding contribution to the current template
31409 requirements. */
31411 {
31414 /* Use UNKNOWN_LOCATION so write_template_args can tell the
31415 difference between this and a fold the user wrote. */
31418 TRUTH_ANDIF_EXPR);
31421 /* If there was a constraint, we also need to replace that in
31422 the template requirements, which we've already built. */
31426 }
31427 }
31433 /* If there are more levels then build up the replacement with the outer
31434 template parms. */
31438 replacement);
31441 }
31443 /* __integer_pack(N) in a pack expansion expands to a sequence of numbers from
31444 0..N-1. */
31446 void
31448 {
31451 integer_type_node,
31452 NULL_TREE),
31456 CP_BUILT_IN_INTEGER_PACK);
31457 }
31459 /* Walk the decl or type specialization table calling FN on each
31460 entry. */
31462 void
31466 {
31472 }
31474 /* Lookup the specialization of *ELT, in the decl or type
31475 specialization table. Return the SPEC that's already there, or
31476 NULL if nothing. */
31478 tree
31480 {
31490 }
31492 /* Return flags encoding whether SPEC is on the instantiation and/or
31493 specialization lists of TMPL. */
31495 unsigned
31497 {
31503 {
31506 }
31511 /* Only need to search if DECL is a partial specialization. */
31515 {
31518 }
31521 }
31523 /* Add a new specialization described by SPEC. DECL is the
31524 maybe-template decl and FLAGS is as returned from
31525 get_mergeable_specialization_flags. */
31527 void
31530 {
31533 {
31542 {
31545 }
31546 }
31549 {
31552 /* We don't distinguish different constrained partial type
31553 specializations, so there could be duplicates. Everything else
31554 must be new. */
31556 {
31562 }
31563 }
31570 {
31571 /* A partial specialization. */
31576 }
31577 }
31579 /* Set up the hash tables for template instantiations. */
31581 void
31583 {
31589 }
31591 /* Print stats about the template hash tables for -fstats. */
31593 void
31595 {
31606 }
31608 #if CHECKING_P
31612 /* Verify that type_dependent_expression_p () works correctly, even
31613 in the presence of location wrapper nodes. */
31615 static void
31617 {
31622 /* If no templates are involved, nothing is type-dependent. */
31628 /* Within a template, an unresolved name is always type-dependent. */
31631 /* Ensure it copes with NULL_TREE and errors. */
31635 /* A USING_DECL in a template should be type-dependent, even if wrapped
31636 with a location wrapper (PR c++/83799). */
31645 }
31647 /* Run all of the selftests within this file. */
31649 void
31651 {
31653 }