| blob | 903a4a1c363011c046620a99e3c8fc8a84cc129f |
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 {
7315 {
7320 }
7324 /* This is no longer a compound literal. */
7328 }
7330 /* The template arguments corresponding to template parameter objects of types
7331 that contain pointers to members. */
7335 /* Find or build an nttp object for (already-validated) EXPR with name
7336 NAME. */
7338 tree
7340 {
7357 {
7358 /* If EXPR contains any PTRMEM_CST, they will get clobbered by
7359 lower_var_init before we're done mangling. So store the original
7360 value elsewhere. */
7363 }
7368 }
7370 /* Return the actual template argument corresponding to template parameter
7371 object VAR. */
7373 tree
7375 {
7379 }
7381 /* Attempt to convert the non-type template parameter EXPR to the
7382 indicated TYPE. If the conversion is successful, return the
7383 converted value. If the conversion is unsuccessful, return
7384 NULL_TREE if we issued an error message, or error_mark_node if we
7385 did not. We issue error messages for out-and-out bad template
7386 parameters, but not simply because the conversion failed, since we
7387 might be just trying to do argument deduction. Both TYPE and EXPR
7388 must be non-dependent.
7390 The conversion follows the special rules described in
7391 [temp.arg.nontype], and it is much more strict than an implicit
7392 conversion.
7394 This function is called twice for each template argument (see
7395 lookup_template_class for a more accurate description of this
7396 problem). This means that we need to handle expressions which
7397 are not valid in a C++ source, but can be created from the
7398 first call (for instance, casts to perform conversions). These
7399 hacks can go away after we fix the double coercion problem. */
7401 static tree
7403 {
7404 tree expr_type;
7407 /* Detect immediately string literals as invalid non-type argument.
7408 This special-case is not needed for correctness (we would easily
7409 catch this later), but only to provide better diagnostic for this
7410 common user mistake. As suggested by DR 100, we do not mention
7411 linkage issues in the diagnostic as this is not the point. */
7413 {
7419 }
7421 /* Add the ADDR_EXPR now for the benefit of
7422 value_dependent_expression_p. */
7425 {
7429 }
7431 /* If we are in a template, EXPR may be non-dependent, but still
7432 have a syntactic, rather than semantic, form. For example, EXPR
7433 might be a SCOPE_REF, rather than the VAR_DECL to which the
7434 SCOPE_REF refers. Preserving the qualifying scope is necessary
7435 so that access checking can be performed when the template is
7436 instantiated -- but here we need the resolved form so that we can
7437 convert the argument. */
7449 /* If the argument is non-dependent, perform any conversions in
7450 non-dependent context as well. */
7458 else
7461 /* 14.3.2/5: The null pointer{,-to-member} conversion is applied
7462 to a non-type argument of "nullptr". */
7466 /* In C++11, integral or enumeration non-type template arguments can be
7467 arbitrary constant expressions. Pointer and pointer to
7468 member arguments can be general constant expressions that evaluate
7469 to a null value, but otherwise still need to be of a specific form. */
7471 {
7473 /* A PTRMEM_CST is already constant, and a valid template
7474 argument for a parameter of pointer to member type, we just want
7475 to leave it in that form rather than lower it to a
7479 {
7480 /* C++17: A template-argument for a non-type template-parameter shall
7481 be a converted constant expression (8.20) of the type of the
7482 template-parameter. */
7485 /* Make sure we return NULL_TREE only if we have really issued
7486 an error, as described above. */
7489 {
7492 }
7495 /* EXPR may have become value-dependent. */
7497 }
7499 {
7504 }
7505 }
7509 else
7512 /* HACK: Due to double coercion, we can get a
7513 NOP_EXPR<REFERENCE_TYPE>(ADDR_EXPR<POINTER_TYPE> (arg)) here,
7514 which is the tree that we built on the first call (see
7515 below when coercing to reference to object or to reference to
7516 function). We just strip everything and get to the arg.
7517 See g++.old-deja/g++.oliva/template4.C and g++.dg/template/nontype9.C
7518 for examples. */
7520 {
7521 /* Check this before we strip *& to avoid redundancy. */
7530 {
7531 /* ??? Maybe we could use convert_from_reference here, but we
7532 would need to relax its constraints because the NOP_EXPR
7533 could actually change the type to something more cv-qualified,
7534 and this is not folded by convert_from_reference. */
7539 && (same_type_ignoring_top_level_qualifiers_p
7542 {
7545 }
7546 }
7547 }
7549 /* [temp.arg.nontype]/5, bullet 1
7551 For a non-type template-parameter of integral or enumeration type,
7552 integral promotions (_conv.prom_) and integral conversions
7553 (_conv.integral_) are applied. */
7556 {
7558 {
7563 }
7568 /* Notice that there are constant expressions like '4 % 0' which
7569 do not fold into integer constants. */
7571 {
7573 {
7577 else
7583 /* else cxx_constant_value complained but gave us
7584 a real constant, so go ahead. */
7586 {
7587 /* Some assemble time constant expressions like
7588 (intptr_t)&&lab1 - (intptr_t)&&lab2 or
7589 4 + (intptr_t)&&var satisfy reduced_constant_expression_p
7590 as we can emit them into .rodata initializers of
7591 variables, yet they can't fold into an INTEGER_CST at
7592 compile time. Refuse them here. */
7597 }
7598 }
7599 else
7601 }
7603 /* Avoid typedef problems. */
7606 }
7607 /* [temp.arg.nontype]/5, bullet 2
7609 For a non-type template-parameter of type pointer to object,
7610 qualification conversions (_conv.qual_) and the array-to-pointer
7611 conversion (_conv.array_) are applied. */
7613 {
7616 /* Look through any NOP_EXPRs around an ADDR_EXPR, whether they come from
7617 decay_conversion or an explicit cast. If it's a problematic cast,
7618 we'll complain about it below. */
7620 {
7625 {
7628 }
7629 }
7631 /* [temp.arg.nontype]/1 (TC1 version, DR 49):
7633 A template-argument for a non-type, non-template template-parameter
7634 shall be one of: [...]
7636 -- the name of a non-type template-parameter;
7637 -- the address of an object or function with external linkage, [...]
7638 expressed as "& id-expression" where the & is optional if the name
7639 refers to a function or array, or if the corresponding
7640 template-parameter is a reference.
7642 Here, we do not care about functions, as they are invalid anyway
7643 for a parameter of type pointer-to-object. */
7646 /* Non-type template parameters are OK. */
7647 ;
7652 /* Other values, like integer constants, might be valid
7653 non-type arguments of some other type. */
7663 }
7664 /* [temp.arg.nontype]/5, bullet 3
7666 For a non-type template-parameter of type reference to object, no
7667 conversions apply. The type referred to by the reference may be more
7668 cv-qualified than the (otherwise identical) type of the
7669 template-argument. The template-parameter is bound directly to the
7670 template-argument, which must be an lvalue. */
7672 {
7674 expr_type))
7678 {
7683 }
7686 {
7691 }
7693 /* [temp.arg.nontype]/1
7695 A template-argument for a non-type, non-template template-parameter
7696 shall be one of: [...]
7698 -- the address of an object or function with external linkage. */
7701 {
7704 {
7707 "because a reference variable does not have a constant "
7710 }
7711 }
7714 /* OK, dependent reference. We don't want to ask whether a DECL is
7716 else
7717 {
7722 }
7726 }
7727 /* [temp.arg.nontype]/5, bullet 4
7729 For a non-type template-parameter of type pointer to function, only
7730 the function-to-pointer conversion (_conv.func_) is applied. If the
7731 template-argument represents a set of overloaded functions (or a
7732 pointer to such), the matching function is selected from the set
7733 (_over.over_). */
7735 {
7736 /* If the argument is a template-id, we might not have enough
7737 context information to decay the pointer. */
7739 {
7743 }
7746 /* Null pointer values are OK in C++11. */
7752 }
7753 /* [temp.arg.nontype]/5, bullet 5
7755 For a non-type template-parameter of type reference to function, no
7756 conversions apply. If the template-argument represents a set of
7757 overloaded functions, the matching function is selected from the set
7758 (_over.over_). */
7760 {
7762 {
7764 {
7769 }
7771 }
7776 }
7777 /* [temp.arg.nontype]/5, bullet 6
7779 For a non-type template-parameter of type pointer to member function,
7780 no conversions apply. If the template-argument represents a set of
7781 overloaded member functions, the matching member function is selected
7782 from the set (_over.over_). */
7784 {
7789 /* [temp.arg.nontype] bullet 1 says the pointer to member
7790 expression must be a pointer-to-member constant. */
7795 /* Repeated conversion can't deal with a conversion that turns PTRMEM_CST
7796 into a CONSTRUCTOR, so build up a new PTRMEM_CST instead. */
7799 }
7800 /* [temp.arg.nontype]/5, bullet 7
7802 For a non-type template-parameter of type pointer to data member,
7803 qualification conversions (_conv.qual_) are applied. */
7805 {
7806 /* [temp.arg.nontype] bullet 1 says the pointer to member
7807 expression must be a pointer-to-member constant. */
7815 }
7817 {
7819 {
7824 }
7826 }
7828 {
7829 /* Replace the argument with a reference to the corresponding template
7830 parameter object. */
7835 }
7836 /* A template non-type parameter must be one of the above. */
7837 else
7840 /* Sanity check: did we actually convert the argument to the
7841 right type? */
7845 }
7847 /* Subroutine of coerce_template_template_parms, which returns 1 if
7848 PARM_PARM and ARG_PARM match using the rule for the template
7849 parameters of template template parameters. Both PARM and ARG are
7850 template parameters; the rest of the arguments are the same as for
7851 coerce_template_template_parms.
7852 */
7853 static int
7855 tree arg,
7856 tsubst_flags_t complain,
7857 tree in_decl,
7858 tree outer_args)
7859 {
7868 {
7870 /* We encounter instantiations of templates like
7871 template <template <template <class> class> class TT>
7872 class C; */
7873 {
7877 }
7878 /* Fall through. */
7883 /* Argument is a parameter pack but parameter is not. */
7888 /* The tsubst call is used to handle cases such as
7890 template <int> class C {};
7891 template <class T, template <T> class TT> class D {};
7892 D<int, C> d;
7894 i.e. the parameter list of TT depends on earlier parameters. */
7896 {
7901 }
7905 /* Argument is a parameter pack but parameter is not. */
7912 }
7915 }
7917 /* Coerce template argument list ARGLIST for use with template
7918 template-parameter TEMPL. */
7920 static tree
7922 tsubst_flags_t complain)
7923 {
7924 /* Consider an example where a template template parameter declared as
7926 template <class T, class U = std::allocator<T> > class TT
7928 The template parameter level of T and U are one level larger than
7929 of TT. To proper process the default argument of U, say when an
7930 instantiation `TT<int>' is seen, we need to build the full
7931 arguments containing {int} as the innermost level. Outer levels,
7932 available when not appearing as default template argument, can be
7933 obtained from the arguments of the enclosing template.
7935 Suppose that TT is later substituted with std::vector. The above
7936 instantiation is `TT<int, std::allocator<T> >' with TT at
7937 level 1, and T at level 2, while the template arguments at level 1
7938 becomes {std::vector} and the inner level 2 is {int}. */
7944 {
7945 /* This is an argument of the current template, so we haven't set
7946 DECL_CONTEXT yet. We can also get here when level-lowering a
7947 bound ttp. */
7948 tree relevant_template_parms;
7950 /* Parameter levels that are greater than the level of the given
7951 template template parm are irrelevant. */
7958 }
7965 }
7967 /* A cache of template template parameters with match-all default
7968 arguments. */
7971 /* T is a bound template template-parameter. Copy its arguments into default
7972 arguments of the template template-parameter's template parameters. */
7974 static tree
7976 {
7999 {
8002 {
8005 }
8006 }
8010 tree gen_ntmpl;
8013 else
8023 }
8025 /* ARG is a bound potential template template-argument, and PARGS is a list
8026 of arguments for the corresponding template template-parameter. Adjust
8027 PARGS as appropriate for application to ARG's template, and if ARG is a
8028 BOUND_TEMPLATE_TEMPLATE_PARM, possibly adjust it to add default template
8029 arguments to the template template parameter. */
8031 static tree
8033 {
8037 {
8038 /* When comparing two template template-parameters in partial ordering,
8039 rewrite the one currently being used as an argument to have default
8040 arguments for all parameters. */
8046 }
8047 else
8048 {
8049 tree aparms
8052 }
8055 }
8057 /* Subroutine of unify for the case when PARM is a
8058 BOUND_TEMPLATE_TEMPLATE_PARM. */
8060 static int
8063 {
8067 /* The template template parm might be variadic and the argument
8068 not, so flatten both argument lists. */
8073 {
8074 /* In keeping with P0522R0, adjust P's template arguments
8075 to apply to A's template; then flatten it again. */
8083 /* If the P0522 adjustment eliminated a pack expansion, deduce
8084 empty packs. */
8090 }
8091 else
8092 {
8093 /* Deduce arguments T, i from TT<T> or TT<i>.
8094 We check each element of PARMVEC and ARGVEC individually
8095 rather than the whole TREE_VEC since they can have
8096 different number of elements, which is allowed under N2555. */
8100 /* Check if the parameters end in a pack, making them
8101 variadic. */
8108 /* If the template argument list of P contains a pack
8109 expansion that is not the last template argument, the
8110 entire template argument list is a non-deduced
8111 context. */
8129 DEDUCE_EXACT,
8132 }
8135 }
8137 /* Return 1 if PARM_TMPL and ARG_TMPL match using rule for
8138 template template parameters.
8140 Consider the example:
8141 template <class T> class A;
8142 template<template <class U> class TT> class B;
8144 For B<A>, PARM_TMPL is TT, while ARG_TMPL is A,
8145 and OUTER_ARGS contains A. */
8147 static int
8149 tree arg_tmpl,
8150 tsubst_flags_t complain,
8151 tree in_decl,
8152 tree outer_args)
8153 {
8167 {
8168 /* P0522R0: A template template-parameter P is at least as specialized as
8169 a template template-argument A if, given the following rewrite to two
8170 function templates, the function template corresponding to P is at
8171 least as specialized as the function template corresponding to A
8172 according to the partial ordering rules for function templates
8173 ([temp.func.order]). Given an invented class template X with the
8174 template parameter list of A (including default arguments):
8176 * Each of the two function templates has the same template parameters,
8177 respectively, as P or A.
8179 * Each function template has a single function parameter whose type is
8180 a specialization of X with template arguments corresponding to the
8181 template parameters from the respective function template where, for
8182 each template parameter PP in the template parameter list of the
8183 function template, a corresponding template argument AA is formed. If
8184 PP declares a parameter pack, then AA is the pack expansion
8185 PP... ([temp.variadic]); otherwise, AA is the id-expression PP.
8187 If the rewrite produces an invalid type, then P is not at least as
8188 specialized as A. */
8190 /* So coerce P's args to apply to A's parms, and then deduce between A's
8191 args and the converted args. If that succeeds, A is at least as
8192 specialized as P, so they match.*/
8198 /* PARM and ARG might be at different template depths, and we want to
8199 pass the right additional levels of args when coercing PARGS to
8200 ARG_PARMS in case we need to do any substitution into non-type
8201 template parameter types.
8203 OUTER_ARGS are not the right outer levels in this case, as they are
8204 the args we're building up for PARM, and for the coercion we want the
8205 args for ARG. If DECL_CONTEXT isn't set for a template template
8206 parameter, we can assume that it's in the current scope. */
8214 {
8219 /* Only use as many levels from the scope as needed
8220 (excluding the level of ARG). */
8224 else
8227 /* Add the arguments that appear at the levels of ARG. */
8234 }
8235 else
8241 {
8247 }
8248 }
8250 /* Determine whether we have a parameter pack at the end of the
8251 template template parameter's template parameter list. */
8253 {
8260 {
8274 }
8275 }
8281 /* Check all of the template parameters except the parameter pack at
8282 the end (if any). */
8284 {
8293 outer_args))
8296 }
8299 {
8300 /* Check each of the template parameters in the template
8301 argument against the template parameter pack at the end of
8302 the template template parameter. */
8309 {
8316 outer_args))
8318 }
8319 }
8322 }
8324 /* Verifies that the deduced template arguments (in TARGS) for the
8325 template template parameters (in TPARMS) represent valid bindings,
8326 by comparing the template parameter list of each template argument
8327 to the template parameter list of its corresponding template
8328 template parameter, in accordance with DR150. This
8329 routine can only be called after all template arguments have been
8330 deduced. It will return TRUE if all of the template template
8331 parameter bindings are okay, FALSE otherwise. */
8332 bool
8334 {
8338 /* We're dealing with template parms in this process. */
8344 {
8349 {
8354 {
8355 /* Look inside the argument pack. */
8358 }
8361 {
8363 /* Extract the next argument from the argument
8364 pack. */
8368 /* Look at the pattern of the pack expansion. */
8371 /* Extract the template parameters from the template
8372 argument. */
8376 /* Verify that we can coerce the template template
8377 parameters from the template argument to the template
8378 parameter. This requires an exact match. */
8380 && !coerce_template_template_parms
8382 targ,
8383 tf_none,
8384 tparm,
8385 targs))
8386 {
8389 }
8390 }
8391 }
8392 }
8394 out:
8398 }
8400 /* Since type attributes aren't mangled, we need to strip them from
8401 template type arguments. */
8403 tree
8405 {
8415 }
8417 /* And from inside dependent non-type arguments like sizeof(Type). */
8419 static tree
8421 {
8431 }
8433 /* A template declaration can be substituted for a constrained
8434 template template parameter only when the argument is no more
8435 constrained than the parameter. */
8437 static bool
8439 {
8442 /* For now, allow constrained template template arguments
8443 and unconstrained template template parameters. */
8447 /* If the template parameter is constrained, we need to rewrite its
8448 constraints in terms of the ARG's template parameters. This ensures
8449 that all of the template parameter types will have the same depth.
8451 Note that this is only valid when coerce_template_template_parm is
8452 true for the innermost template parameters of PARM and ARG. In other
8453 words, because coercion is successful, this conversion will be valid. */
8456 {
8466 }
8469 }
8471 // Convert a placeholder argument into a binding to the original
8472 // parameter. The original parameter is saved as the TREE_TYPE of
8473 // ARG.
8476 {
8479 }
8481 /* We can't fully resolve ARG given as a non-type template argument to TYPE,
8482 because one of them is dependent. But we need to represent the
8483 conversion for the benefit of cp_tree_equal. */
8485 static tree
8487 {
8488 /* Auto parms get no conversion. */
8491 /* ??? Do we need to push the IMPLICIT_CONV_EXPR into the pack expansion?
8492 That would complicate other things, and it doesn't seem necessary. */
8495 /* We don't need or want to add this conversion now if we're going to use the
8496 argument for deduction. */
8511 }
8513 /* Convert the indicated template ARG as necessary to match the
8514 indicated template PARM. Returns the converted ARG, or
8515 error_mark_node if the conversion was unsuccessful. Error and
8516 warning messages are issued under control of COMPLAIN. This
8517 conversion is for the Ith parameter in the parameter list. ARGS is
8518 the full set of template arguments deduced so far. */
8520 static tree
8522 tree arg,
8523 tree args,
8524 tsubst_flags_t complain,
8526 tree in_decl)
8527 {
8528 tree orig_arg;
8529 tree val;
8535 /* Trivially convert placeholders. */
8544 {
8545 /* The template argument was the name of some
8546 member function. That's usually
8547 invalid, but static members are OK. In any
8548 case, grab the underlying fields/functions
8549 and issue an error later if required. */
8551 }
8559 /* When determining whether an argument pack expansion is a template,
8560 look at the pattern. */
8564 /* Deal with an injected-class-name used as a template template arg. */
8566 {
8569 {
8579 }
8580 }
8582 is_tmpl_type =
8598 {
8600 {
8604 }
8607 "to refer to a type member of a template parameter, "
8612 typename_type,
8613 complain);
8616 }
8618 {
8620 {
8622 {
8627 {
8628 /* The template argument is a type, but we're expecting
8629 an expression. */
8634 /* [temp.arg]/2: "In a template-argument, an ambiguity
8635 between a type-id and an expression is resolved to a
8636 type-id, regardless of the form of the corresponding
8637 template-parameter." So give the user a clue. */
8640 "for non-type template parameter is treated as "
8642 }
8646 else
8649 }
8650 }
8652 }
8654 {
8656 {
8663 else
8666 }
8668 }
8671 /* We already did the appropriate conversion when packing args. */
8674 {
8676 {
8678 /* The number of argument required is not known yet.
8679 Just accept it for now. */
8681 else
8682 {
8683 /* Strip alias templates that are equivalent to another
8684 template. */
8689 args))
8690 {
8693 /* TEMPLATE_TEMPLATE_PARM node is preferred over
8694 TEMPLATE_DECL. */
8696 {
8701 }
8702 }
8703 else
8704 {
8706 {
8713 }
8716 }
8718 // Check that the constraints are compatible before allowing the
8719 // substitution.
8722 {
8724 {
8730 }
8732 }
8733 }
8734 }
8735 else
8737 /* We only form one instance of each template specialization.
8738 Therefore, if we use a non-canonical variant (i.e., a
8739 typedef), any future messages referring to the type will use
8740 the typedef, which is confusing if those future uses do not
8741 themselves also use the typedef. */
8744 }
8745 else
8746 {
8751 /* We don't have enough levels of args to do any substitution. This
8754 {
8759 }
8760 else
8763 /* Perform array-to-pointer and function-to-pointer conversion
8764 as per [temp.param]/10. */
8770 /* Drop top-level cv-qualifiers on the substituted/deduced type of
8771 this non-type template parameter, as per [temp.param]/6. */
8777 /* We need to handle arguments for alias or concept templates
8778 differently: we need to force building an IMPLICIT_CONV_EXPR, because
8779 these arguments are going to be substituted directly into the
8780 dependent type; they might not get another chance at
8781 convert_nontype_argument. But if the argument ends up here again for
8782 a template that isn't one of those, remove the conversion for
8783 consistency between naming the same dependent type directly or through
8784 an alias. */
8795 /* We used to call digest_init here. However, digest_init
8796 will report errors, which we don't want when complain
8797 is zero. More importantly, digest_init will try too
8798 hard to convert things: for example, `0' should not be
8799 converted to pointer type at this point according to
8800 the standard. Accepting this is not merely an
8801 extension, since deciding whether or not these
8802 conversions can occur is part of determining which
8803 function template to call, or whether a given explicit
8804 argument specification is valid. */
8806 else
8807 {
8810 }
8820 {
8821 /* Reject template arguments that are references to built-in
8822 functions with no library fallbacks. */
8831 }
8834 {
8835 /* Strip typedefs from the SCOPE_REF. */
8838 complain);
8841 }
8842 }
8845 }
8847 /* Coerces the remaining template arguments in INNER_ARGS (from
8848 ARG_IDX to the end) into the parameter pack at PARM_IDX in PARMS.
8849 Returns the coerced argument pack. PARM_IDX is the position of this
8850 parameter in the template parameter list. ARGS is the original
8851 template argument list. */
8852 static tree
8855 tree args,
8856 tree inner_args,
8858 tree new_args,
8860 tree in_decl,
8861 tsubst_flags_t complain)
8862 {
8865 tree packed_args;
8866 tree argument_pack;
8873 {
8874 /* When the template parameter is a non-type template parameter pack
8875 or template template parameter pack whose type or template
8876 parameters use parameter packs, we know exactly how many arguments
8877 we are looking for. Build a vector of the instantiated decls for
8878 these template parameters in PACKED_PARMS. */
8879 /* We can't use make_pack_expansion here because it would interpret a
8880 _DECL as a use rather than a declaration. */
8894 /* If we're doing a partial instantiation of a member template,
8895 verify that all of the types used for the non-type
8896 template parameter pack are, in fact, valid for non-type
8897 template parameters. */
8900 {
8903 {
8908 }
8909 /* We don't know how many args we have yet, just
8910 use the unconverted ones for now. */
8912 }
8915 }
8916 /* Check if we have a placeholder pack, which indicates we're
8917 in the context of a introduction list. In that case we want
8918 to match this pack to the single placeholder. */
8922 {
8925 }
8926 else
8929 /* Convert the remaining arguments, which will be a part of the
8930 parameter pack "parm". */
8933 {
8939 {
8940 /* Once we've packed as many args as we have types, stop. */
8944 /* We don't know how many args we have yet, just
8945 use the unconverted ones for now. */
8947 else
8949 }
8952 {
8955 }
8956 else
8959 in_decl);
8963 }
8967 {
8972 }
8977 else
8978 {
8981 }
8988 }
8990 /* Returns the number of pack expansions in the template argument vector
8991 ARGS. */
8993 static int
8995 {
9000 {
9004 }
9006 }
9008 /* Convert all template arguments to their appropriate types, and
9009 return a vector containing the innermost resulting template
9010 arguments. If any error occurs, return error_mark_node. Error and
9011 warning messages are issued under control of COMPLAIN.
9013 If PARMS represents all template parameters levels, this function
9014 returns a vector of vectors representing all the resulting argument
9015 levels. Note that in this case, only the innermost arguments are
9016 coerced because the outermost ones are supposed to have been coerced
9017 already. Otherwise, if PARMS represents only (the innermost) vector
9018 of parameters, this function returns a vector containing just the
9019 innermost resulting arguments.
9021 If REQUIRE_ALL_ARGS is false, argument deduction will be performed
9022 for arguments not specified in ARGS. If REQUIRE_ALL_ARGS is true,
9023 arguments not specified in ARGS must have default arguments which
9024 we'll use to fill in ARGS. */
9026 tree
9028 tree args,
9029 tree in_decl,
9030 tsubst_flags_t complain,
9032 {
9034 tree orig_inner_args;
9035 tree inner_args;
9037 /* When used as a boolean value, indicates whether this is a
9038 variadic template parameter list. Since it's an int, we can also
9039 subtract it from nparms to get the number of non-variadic
9040 parameters. */
9045 /* Adjustment to nparms for fixed parameter packs. */
9050 /* Likewise for parameters with default arguments. */
9058 {
9060 {
9063 }
9065 }
9069 /* Determine if there are any parameter packs or default arguments. */
9071 {
9079 }
9082 /* If there are no parameters that follow a parameter pack, we need to
9083 expand any argument packs so that we can deduce a parameter pack from
9084 some non-packed args followed by an argument pack, as in variadic85.C.
9085 If there are such parameters, we need to leave argument packs intact
9086 so the arguments are assigned properly. This can happen when dealing
9087 with a nested class inside a partial specialization of a class
9088 template, as in variadic92.C, or when deducing a template parameter pack
9089 from a sub-declarator, as in variadic114.C. */
9093 /* Count any pack expansion args. */
9099 && require_all_args
9100 && !variadic_args_p
9103 {
9104 bad_nargs:
9106 {
9108 {
9112 }
9113 else
9120 }
9123 }
9124 /* We can't pass a pack expansion to a non-pack parameter of an alias
9125 template (DR 1430). */
9129 && variadic_args_p
9131 {
9133 {
9135 {
9141 {
9144 "pack expansion argument for non-pack parameter "
9146 else
9148 "pack expansion argument for non-pack parameter "
9152 }
9153 }
9155 found:;
9156 }
9158 }
9160 /* We need to evaluate the template arguments, even though this
9161 template-id may be nested within a "sizeof". */
9162 cp_evaluated ev;
9168 {
9169 tree arg;
9170 tree parm;
9172 /* Get the Ith template parameter. */
9176 {
9179 }
9181 /* Calculate the next argument. */
9184 else
9190 {
9191 /* Some arguments will be placed in the
9192 template parameter pack PARM. */
9199 {
9200 /* We don't know how many args we have yet, just use the
9201 unconverted (and still packed) ones for now. */
9205 }
9209 /* Store this argument. */
9211 {
9212 lost++;
9213 /* We are done with all of the arguments. */
9216 }
9217 else
9218 {
9222 {
9225 }
9226 }
9229 }
9231 {
9233 {
9234 /* "If every valid specialization of a variadic template
9235 requires an empty template parameter pack, the template is
9236 ill-formed, no diagnostic required." So check that the
9237 pattern works with this parameter. */
9242 in_decl);
9244 {
9249 }
9251 /* Recover from missing typename. */
9255 /* We don't know how many args we have yet, just
9256 use the unconverted ones for now. */
9260 }
9261 }
9263 {
9264 /* There must be a default arg in this case. */
9267 /* The position of the first default template argument,
9268 is also the number of non-defaulted arguments in NEW_INNER_ARGS.
9269 Record that. */
9273 }
9274 else
9278 {
9281 }
9283 {
9284 /* This can occur if there was an error in the template
9285 parameter list itself (which we would already have
9286 reported) that we are trying to recover from, e.g., a class
9287 template with a parameter list such as
9288 template<typename..., typename> (cpp0x/variadic150.C). */
9291 /* This can also happen with a fixed parameter pack (71834). */
9294 }
9295 else
9301 lost++;
9304 }
9307 {
9308 /* If we had fixed parameter packs, we didn't know how many arguments we
9309 actually needed earlier; now we do. */
9313 }
9316 {
9317 /* We had some pack expansion arguments that will only work if the packs
9318 are empty, but wait until instantiation time to complain.
9319 See variadic-ttp3.C. */
9321 /* Except that we can't provide empty packs to alias templates or
9322 concepts when there are no corresponding parameters. Basically,
9323 we can get here with this:
9325 template<typename T> concept C = true;
9327 template<typename... Args>
9328 requires C<Args...>
9329 void f();
9331 When parsing C<Args...>, we try to form a concept check of
9332 C<?, Args...>. Without the extra check for substituting an empty
9333 pack past the last parameter, we can accept the check as valid.
9335 FIXME: This may be valid for alias templates (but I doubt it).
9337 FIXME: The error could be better also. */
9339 {
9344 }
9355 }
9358 {
9361 }
9368 }
9370 /* Returns true if T is a wrapper to make a C++20 template parameter
9371 object const. */
9373 static bool
9375 {
9381 }
9383 /* Returns 1 if template args OT and NT are equivalent. */
9385 int
9387 {
9400 /* DR 1558: Don't treat an alias template specialization with dependent
9401 arguments as equivalent to its underlying type when used as a template
9402 argument; we need them to be distinct so that we substitute into the
9403 specialization arguments at instantiation time. And aliases can't be
9404 equivalent without being ==, so we don't need to look any deeper.
9406 During partial ordering, however, we need to treat them normally so we can
9407 order uses of the same alias with different cv-qualification (79960). */
9413 /* For member templates */
9426 {
9430 }
9431 else
9432 {
9433 /* Try to treat a template non-type argument that has been converted
9434 to the parameter type as equivalent to one that hasn't yet. */
9448 }
9449 }
9451 /* Returns true iff the OLDARGS and NEWARGS are in fact identical sets of
9452 template arguments. Returns false otherwise, and updates OLDARG_PTR and
9453 NEWARG_PTR with the offending arguments if they are non-NULL. */
9455 bool
9458 {
9469 {
9474 {
9480 }
9481 }
9483 }
9485 static bool
9487 {
9492 }
9494 /* Implement a freelist interface for objects of type T.
9496 Head is a separate object, rather than a regular member, so that we
9497 can define it as a GTY deletable pointer, which is highly
9498 desirable. A data member could be declared that way, but then the
9499 containing object would implicitly get GTY((user)), which would
9500 prevent us from instantiating freelists as global objects.
9501 Although this way we can create freelist global objects, they're
9502 such thin wrappers that instantiating temporaries at every use
9503 loses nothing and saves permanent storage for the freelist object.
9505 Member functions next, anew, poison and reinit have default
9506 implementations that work for most of the types we're interested
9507 in, but if they don't work for some type, they should be explicitly
9508 specialized. See the comments before them for requirements, and
9509 the example specializations for the tree_list_freelist. */
9511 class freelist
9512 {
9513 /* Return the next object in a chain. We could just do type
9514 punning, but if we access the object with its underlying type, we
9515 avoid strict-aliasing trouble. This needs only work between
9516 poison and reinit. */
9519 /* Return a newly allocated, uninitialized or minimally-initialized
9520 object of type T. Any initialization performed by anew should
9521 either remain across the life of the object and the execution of
9522 poison, or be redone by reinit. */
9525 /* Optionally scribble all over the bits holding the object, so that
9526 they become (mostly?) uninitialized memory. This is called while
9527 preparing to make the object part of the free list. */
9532 #ifdef ENABLE_GC_CHECKING
9533 /* Poison the data, to indicate the data is garbage. */
9536 #endif
9537 /* Let valgrind know the object is free. */
9540 /* Let valgrind know the next portion of the object is available,
9541 but uninitialized. */
9543 }
9545 /* Bring an object that underwent at least one lifecycle after anew
9546 and before the most recent free and poison, back to a usable
9547 state, reinitializing whatever is needed for it to be
9548 functionally equivalent to an object just allocated and returned
9549 by anew. This may poison or clear the next field, used by
9550 freelist housekeeping after poison was called. */
9554 #ifdef ENABLE_GC_CHECKING
9556 #endif
9557 /* Let valgrind know the entire object is available, but
9558 uninitialized. */
9560 }
9562 /* Reference a GTY-deletable pointer that points to the first object
9563 in the free list proper. */
9566 /* Construct a freelist object chaining objects off of HEAD. */
9569 /* Add OBJ to the free object list. The former head becomes OBJ's
9570 successor. */
9572 {
9576 }
9578 /* Take an object from the free list, if one is available, or
9579 allocate a new one. Objects taken from the free list should be
9580 regarded as filled with garbage, except for bits that are
9581 configured to be preserved across free and alloc. */
9583 {
9585 {
9590 }
9591 else
9593 }
9594 };
9596 /* Explicitly specialize the interfaces for freelist<tree_node>: we
9597 want to allocate a TREE_LIST using the usual interface, and ensure
9598 TREE_CHAIN remains functional. Alas, we have to duplicate a bit of
9599 build_tree_list logic in reinit, so this could go out of sync. */
9603 {
9605 }
9607 inline tree
9609 {
9611 }
9615 {
9621 #ifdef ENABLE_GC_CHECKING
9624 /* Poison the data, to indicate the data is garbage. */
9627 #endif
9628 /* Let valgrind know the object is free. */
9630 /* But we still want to use the TREE_CODE and TREE_CHAIN parts. */
9634 #ifdef ENABLE_GC_CHECKING
9636 /* Keep TREE_CHAIN functional. */
9638 #else
9640 #endif
9641 }
9645 {
9648 #ifdef ENABLE_GC_CHECKING
9652 #endif
9654 /* Let valgrind know the entire object is available, but
9655 uninitialized. */
9658 #ifdef ENABLE_GC_CHECKING
9660 #else
9663 #endif
9665 }
9667 /* Point to the first object in the TREE_LIST freelist. */
9669 /* Return the/an actual TREE_LIST freelist. */
9672 {
9674 }
9676 /* Point to the first object in the tinst_level freelist. */
9678 /* Return the/an actual tinst_level freelist. */
9681 {
9683 }
9685 /* Point to the first object in the pending_template freelist. */
9687 /* Return the/an actual pending_template freelist. */
9690 {
9692 }
9694 /* Build the TREE_LIST object out of a split list, store it
9695 permanently, and return it. */
9696 tree
9698 {
9707 }
9711 /* Increment OBJ's refcount unless it is already infinite. */
9714 {
9718 }
9720 /* Release storage for OBJ and node, if it's a TREE_LIST. */
9721 void
9723 {
9727 }
9729 /* Decrement OBJ's refcount if not infinite. If it reaches zero, release
9730 OBJ's DECL and OBJ, and start over with the tinst_level object that
9731 used to be referenced by OBJ's NEXT. */
9732 static void
9734 {
9738 {
9742 }
9743 }
9745 /* Modify PTR so that it points to OBJ, adjusting the refcounts of OBJ
9746 and of the former PTR. Omitting the second argument is equivalent
9747 to passing (T*)NULL; this is allowed because passing the
9748 zero-valued integral constant NULL confuses type deduction and/or
9749 overload resolution. */
9751 static void
9753 {
9757 }
9759 static void
9761 {
9771 /* We are called both from instantiate_decl, where we've already had a
9772 tinst_level pushed, and instantiate_template, where we haven't.
9773 Compensate. */
9775 level = !current_tinst_level
9787 else
9796 }
9799 /* Return a TEMPLATE_ID_EXPR corresponding to the indicated FNS and
9800 ARGLIST. Valid choices for FNS are given in the cp-tree.def
9801 documentation for TEMPLATE_ID_EXPR. */
9803 tree
9805 {
9812 {
9815 }
9818 {
9821 unknown_type_node,
9823 arglist);
9825 }
9828 }
9830 /* Within the scope of a template class S<T>, the name S gets bound
9831 (in build_self_reference) to a TYPE_DECL for the class, not a
9832 TEMPLATE_DECL. If DECL is a TYPE_DECL for current_class_type,
9833 or one of its enclosing classes, and that type is a template,
9834 return the associated TEMPLATE_DECL. Otherwise, the original
9835 DECL is returned.
9837 Also handle the case when DECL is a TREE_LIST of ambiguous
9838 injected-class-names from different bases. */
9840 tree
9842 {
9846 /* DR 176: A lookup that finds an injected-class-name (10.2
9847 [class.member.lookup]) can result in an ambiguity in certain cases
9848 (for example, if it is found in more than one base class). If all of
9849 the injected-class-names that are found refer to specializations of
9850 the same class template, and if the name is followed by a
9851 template-argument-list, the reference refers to the class template
9852 itself and not a specialization thereof, and is not ambiguous. */
9854 {
9857 {
9863 }
9866 else
9868 }
9874 }
9876 /* Given an IDENTIFIER_NODE (or type TEMPLATE_DECL) and a chain of
9877 parameters, find the desired type.
9879 D1 is the PTYPENAME terminal, and ARGLIST is the list of arguments.
9881 IN_DECL, if non-NULL, is the template declaration we are trying to
9882 instantiate.
9884 If ENTERING_SCOPE is nonzero, we are about to enter the scope of
9885 the class we are looking up.
9887 Issue error and warning messages under control of COMPLAIN.
9889 If the template class is really a local class in a template
9890 function, then the FUNCTION_CONTEXT is the function in which it is
9891 being instantiated.
9893 ??? Note that this function is currently called *twice* for each
9894 template-id: the first time from the parser, while creating the
9895 incomplete type (finish_template_type), and the second type during the
9896 real instantiation (instantiate_template_class). This is surely something
9897 that we want to avoid. It also causes some problems with argument
9898 coercion (see convert_nontype_argument for more information on this). */
9900 tree
9903 {
9907 tree t;
9910 spec_entry elt;
9911 hashval_t hash;
9914 {
9918 else
9919 {
9926 }
9927 }
9929 {
9932 /* If we are declaring a constructor, say A<T>::A<T>, we will get
9933 an implicit typename for the second A. Deal with it. */
9938 {
9941 }
9942 }
9945 {
9948 }
9950 {
9953 }
9955 {
9958 }
9960 /* Issue an error message if we didn't find a template. */
9962 {
9966 }
9969 /* Make sure it's a user visible template, if it was named by
9970 the user. */
9973 {
9975 {
9979 }
9981 }
9985 /* An alias that just changes the name of a template is equivalent to the
9986 other template, so if any of the arguments are pack expansions, strip
9987 the alias to avoid problems with a pack expansion passed to a non-pack
9988 alias template parameter (DR 1430). */
9993 {
9994 tree parm;
10003 }
10004 else
10005 {
10007 tree gen_tmpl;
10008 tree type_decl;
10016 /* An error occurred while building the template TEMPL, and a
10017 diagnostic has most certainly been emitted for that
10018 already. Let's propagate that error. */
10030 {
10031 /* We've been given an incomplete set of template arguments.
10032 For example, given:
10034 template <class T> struct S1 {
10035 template <class U> struct S2 {};
10036 template <class U> struct S2<U*> {};
10037 };
10039 we will be called with an ARGLIST of `U*', but the
10040 TEMPLATE will be `template <class T> template
10041 <class U> struct S1<T>::S2'. We must fill in the missing
10042 arguments. */
10046 }
10048 /* Now we should have enough arguments. */
10051 /* From here on, we're only interested in the most general
10052 template. */
10054 /* Shortcut looking up the current class scope again. */
10058 {
10069 }
10071 /* Calculate the BOUND_ARGS. These will be the args that are
10072 actually tsubst'd into the definition to create the
10073 instantiation. */
10078 /* We were unable to bind the arguments. */
10081 /* In the scope of a template class, explicit references to the
10082 template class refer to the type of the template, not any
10083 instantiation of it. For example, in:
10085 template <class T> class C { void f(C<T>); }
10087 the `C<T>' is just the same as `C'. Outside of the
10088 class, however, such a reference is an instantiation. */
10092 {
10097 }
10099 /* If we already have this specialization, return it. */
10109 /* If the template's constraints are not satisfied,
10110 then we cannot form a valid type.
10112 Note that the check is deferred until after the hash
10113 lookup. This prevents redundant checks on previously
10114 instantiated specializations. */
10118 {
10120 {
10121 auto_diagnostic_group d;
10124 }
10126 }
10130 /* If the deduced arguments are invalid, then the binding
10131 failed. */
10135 complain))
10142 /* This occurs when the user has tried to define a tagged type
10143 in a scope that forbids it. We emitted an error during the
10144 parse. We didn't complete the bail out then, so here we
10145 are. */
10150 {
10152 /* If the context of the partially instantiated template is
10153 already non-dependent, then we might as well use it. */
10155 else
10156 {
10159 /* Try completing the enclosing context if it's not already so. */
10162 {
10165 {
10166 /* Completion could have caused us to register the desired
10167 specialization already, so check the table again. */
10171 }
10172 }
10173 }
10174 }
10175 else
10184 /* Create the type. */
10186 {
10187 /* The user referred to a specialization of an alias
10188 template represented by GEN_TMPL.
10190 [temp.alias]/2 says:
10192 When a template-id refers to the specialization of an
10193 alias template, it is equivalent to the associated
10194 type obtained by substitution of its
10195 template-arguments for the template-parameters in the
10196 type-id of the alias template. */
10199 /* Note that the call above (by indirectly calling
10200 register_specialization in tsubst_decl) registers the
10201 TYPE_DECL representing the specialization of the alias
10202 template. So next time someone substitutes ARGLIST for
10203 the template parms into the alias template (GEN_TMPL),
10204 she'll get that TYPE_DECL back. */
10208 }
10210 {
10212 {
10223 }
10224 else
10225 {
10226 /* We don't want to call start_enum for this type, since
10227 the values for the enumeration constants may involve
10228 template parameters. And, no one should be interested
10229 in the enumeration constants for such a type. */
10232 }
10236 }
10238 {
10239 /* Lambda closures are regenerated in tsubst_lambda_expr, not
10240 instantiated here. */
10248 /* A local class. Make sure the decl gets registered properly. */
10255 /* This instantiation is another name for the primary
10256 template type. Set the TYPE_CANONICAL field
10257 appropriately. */
10261 }
10262 else
10265 /* If we called start_enum or pushtag above, this information
10266 will already be set up. */
10269 {
10276 }
10279 /* Although GEN_TMPL is the TEMPLATE_DECL, it has the same value
10280 of export flag. We want to propagate this because it might
10281 be a friend declaration that pushes a new hidden binding. */
10285 {
10291 {
10294 }
10295 }
10299 {
10303 {
10304 tree attributes
10312 }
10313 }
10315 /* Let's consider the explicit specialization of a member
10316 of a class template specialization that is implicitly instantiated,
10317 e.g.:
10318 template<class T>
10319 struct S
10320 {
10321 template<class U> struct M {}; //#0
10322 };
10324 template<>
10325 template<>
10326 struct S<int>::M<char> //#1
10327 {
10328 int i;
10329 };
10330 [temp.expl.spec]/4 says this is valid.
10332 In this case, when we write:
10333 S<int>::M<char> m;
10335 M is instantiated from the CLASSTYPE_TI_TEMPLATE of #1, not from
10336 the one of #0.
10338 When we encounter #1, we want to store the partial instantiation
10339 of M (template<class T> S<int>::M<T>) in its CLASSTYPE_TI_TEMPLATE.
10341 For all cases other than this "explicit specialization of member of a
10342 class template", we just want to store the most general template into
10343 the CLASSTYPE_TI_TEMPLATE of M.
10345 This case of "explicit specialization of member of a class template"
10346 only happens when:
10347 1/ the enclosing class is an instantiation of, and therefore not
10348 the same as, the context of the most general template, and
10349 2/ we aren't looking at the partial instantiation itself, i.e.
10350 the innermost arguments are not the same as the innermost parms of
10351 the most general template.
10353 So it's only when 1/ and 2/ happens that we want to use the partial
10354 instantiation of the member template in lieu of its most general
10355 template. */
10359 /* the enclosing class must be an instantiation... */
10362 {
10366 tree partial_inst_args =
10373 use_partial_inst_tmpl =
10374 /*...and we must not be looking at the partial instantiation
10375 itself. */
10377 partial_inst_args);
10378 }
10381 /* This case is easy; there are no member templates involved. */
10383 else
10384 {
10385 /* This is a full instantiation of a member template. Find
10386 the partial instantiation of which this is an instance. */
10388 /* Temporarily reduce by one the number of levels in the ARGLIST
10389 so as to avoid comparing the last set of arguments. */
10391 /* We don't use COMPLAIN in the following call because this isn't
10392 the immediate context of deduction. For instance, tf_partial
10393 could be set here as we might be at the beginning of template
10394 argument deduction when any explicitly specified template
10395 arguments are substituted into the function type. tf_partial
10396 could lead into trouble because we wouldn't find the partial
10397 instantiation that might have been created outside tf_partial
10398 context, because the levels of template parameters wouldn't
10399 match, because in a tf_partial context, tsubst doesn't reduce
10400 TEMPLATE_PARM_LEVEL. */
10403 /* FOUND is either a proper class type, or an alias
10404 template specialization. In the later case, it's a
10405 TYPE_DECL, resulting from the substituting of arguments
10406 for parameters in the TYPE_DECL of the alias template
10407 done earlier. So be careful while getting the template
10408 of FOUND. */
10410 ? found
10417 {
10418 /* If this partial instantiation is specialized, we want to
10419 use it for hash table lookup. */
10423 }
10424 }
10426 /* Build template info for the new specialization. */
10436 /* Note this use of the partial instantiation so we can check it
10437 later in maybe_process_partial_specialization. */
10445 /* Now that the type has been registered on the instantiations
10446 list, we set up the enumerators. Because the enumeration
10447 constants may involve the enumeration type itself, we make
10448 sure to register the type first, and then create the
10449 constants. That way, doing tsubst_expr for the enumeration
10450 constants won't result in recursive calls here; we'll find
10451 the instantiation and exit above. */
10455 /* If the type makes use of template parameters, the
10456 code that generates debugging information will crash. */
10459 /* Possibly limit visibility based on template args. */
10466 }
10467 }
10469 /* Return a TEMPLATE_ID_EXPR for the given variable template and ARGLIST. */
10471 tree
10473 {
10484 /* The type of the expression is NULL_TREE since the template-id could refer
10485 to an explicit or partial specialization. */
10487 }
10489 /* Instantiate a variable declaration from a TEMPLATE_ID_EXPR if it's
10490 not dependent. */
10492 tree
10494 {
10498 /* If the template or arguments are dependent, then we
10499 can't resolve the TEMPLATE_ID_EXPR yet. */
10505 {
10507 {
10508 auto_diagnostic_group d;
10511 }
10513 }
10516 }
10518 /* Construct a TEMPLATE_ID_EXPR for the given variable template TEMPL having
10519 TARGS template args, and instantiate it if it's not dependent. */
10521 tree
10523 tsubst_flags_t complain)
10524 {
10531 }
10533 /* If the set of template parameters PARMS contains a template parameter
10534 at the given LEVEL and INDEX, then return this parameter. Otherwise
10535 return NULL_TREE. */
10537 static tree
10539 {
10548 }
10550 /* Return the TREE_LIST for the template parameter from PARMS that positionally
10551 corresponds to the template parameter PARM, or else return NULL_TREE. */
10553 static tree
10555 {
10559 }
10561 /* As above, but pull out the actual parameter. */
10563 static tree
10565 {
10571 /* As in template_parm_to_arg. */
10574 else
10579 }
10580 \f
10581 struct pair_fn_data
10582 {
10583 tree_fn_t fn;
10584 tree_fn_t any_fn;
10586 /* True when we should also visit template parameters that occur in
10587 non-deduced contexts. */
10590 };
10592 /* Called from for_each_template_parm via walk_tree. */
10594 static tree
10596 {
10603 #define WALK_SUBTREE(NODE) \
10604 do \
10605 { \
10606 result = for_each_template_parm (NODE, fn, data, pfd->visited, \
10607 pfd->include_nondeduced_p, \
10608 pfd->any_fn); \
10609 if (result) goto out; \
10610 } \
10611 while (0)
10621 {
10625 /* Fall through. */
10631 else
10641 /* Since we're not going to walk subtrees, we have to do this
10642 explicitly here. */
10644 /* Fall through. */
10647 /* Check the return type. */
10650 /* Check the parameter types. Since default arguments are not
10651 instantiated until they are needed, the TYPE_ARG_TYPES may
10652 contain expressions that involve template parameters. But,
10653 no-one should be looking at them yet. And, once they're
10654 instantiated, they don't contain template parameters, so
10655 there's no point in looking at them then, either. */
10656 {
10657 tree parm;
10662 /* Since we've already handled the TYPE_ARG_TYPES, we don't
10663 want walk_tree walking into them itself. */
10665 }
10668 {
10672 }
10688 {
10691 }
10714 /* Record template parameters such as `T' inside `TT<T>'. */
10716 /* Fall through. */
10728 /* A template template parameter is encountered. */
10732 /* Already substituted template template parameter */
10737 /* A template-id in a TYPENAME_TYPE might be a deduced context after
10738 partial instantiation. */
10745 /* If there's no type, then this thing must be some expression
10746 involving template parameters. */
10756 /* These are non-deduced contexts. */
10778 }
10780 #undef WALK_SUBTREE
10782 /* We didn't find any template parameters we liked. */
10783 out:
10785 }
10787 /* For each TEMPLATE_TYPE_PARM, TEMPLATE_TEMPLATE_PARM,
10788 BOUND_TEMPLATE_TEMPLATE_PARM or TEMPLATE_PARM_INDEX in T,
10789 call FN with the parameter and the DATA.
10790 If FN returns nonzero, the iteration is terminated, and
10791 for_each_template_parm returns 1. Otherwise, the iteration
10792 continues. If FN never returns a nonzero value, the value
10793 returned by for_each_template_parm is 0. If FN is NULL, it is
10794 considered to be the function which always returns 1.
10796 If INCLUDE_NONDEDUCED_P, then this routine will also visit template
10797 parameters that occur in non-deduced contexts. When false, only
10798 visits those template parameters that can be deduced. */
10800 static tree
10804 tree_fn_t any_fn)
10805 {
10807 tree result;
10809 /* Set up. */
10815 /* Walk the tree. (Conceptually, we would like to walk without
10816 duplicates, but for_each_template_parm_r recursively calls
10817 for_each_template_parm, so we would need to reorganize a fair
10818 bit to use walk_tree_without_duplicates, so we keep our own
10819 visited list.) */
10822 else
10825 for_each_template_parm_r,
10829 /* Clean up. */
10831 {
10834 }
10837 }
10839 struct find_template_parameter_info
10840 {
10844 {}
10850 tree ctx_parms;
10857 };
10859 /* Appends the declaration of T to the list in DATA. */
10861 static int
10863 {
10866 /* Template parameters declared within the expression are not part of
10867 the parameter mapping. For example, in this concept:
10869 template<typename T>
10870 concept C = requires { <expr> } -> same_as<int>;
10872 the return specifier same_as<int> declares a new decltype parameter
10873 that must not be part of the parameter mapping. The same is true
10874 for generic lambda parameters, lambda template parameters, etc. */
10882 /* We want the underlying TEMPLATE_TEMPLATE_PARM, not the
10883 BOUND_TEMPLATE_TEMPLATE_PARM itself. */
10886 /* This template parameter might be an argument to a cached dependent
10887 specalization that was formed earlier inside some other template, in
10888 which case the parameter is not among the ones that are in-scope.
10889 Look in CTX_PARMS to find the corresponding in-scope template
10890 parameter, and use it instead. */
10894 /* Arguments like const T yield parameters like const T. This means that
10895 a template-id like X<T, const T> would yield two distinct parameters:
10896 T and const T. Adjust types to their unqualified versions. */
10900 {
10901 /* Append T to PARM_LIST. */
10905 }
10907 /* Verify the parameter we found has a valid index. */
10909 {
10915 }
10918 }
10920 /* Ensure that we recursively examine certain terms that are not normally
10921 visited in for_each_template_parm_r. */
10923 static int
10925 {
10928 #define WALK_SUBTREE(NODE) \
10929 do \
10930 { \
10931 for_each_template_parm (NODE, keep_template_parm, data, \
10932 &ftpi->visited, true, \
10933 any_template_parm_r); \
10934 } \
10935 while (0)
10937 /* A mention of a member alias/typedef is a use of all of its template
10938 arguments, including those from the enclosing class, so we don't use
10939 alias_template_specialization_p here. */
10945 {
10947 /* Type constraints of a placeholder type may contain parameters. */
10954 /* Search through references to variable templates. */
10964 /* If T is a member template that shares template parameters with
10965 ctx_parms, we need to mark all those parameters for mapping.
10966 To that end, it should suffice to just walk the DECL_CONTEXT of
10967 the template (assuming the template is not overly general). */
10972 {
10973 /* Look in the parms and body. */
10977 }
10982 /* The conversion-type-id of a conversion operator may be dependent. */
10993 }
10995 /* Keep walking. */
10997 }
10999 /* Look through T for template parameters. */
11001 tree
11003 {
11006 any_template_parm_r);
11007 }
11009 /* As above, but also recursively look into the default arguments of template
11010 parameters we found. Used for alias CTAD. */
11012 tree
11014 {
11017 /* Since newly found parms are added to the end of the list, we
11018 can just walk it until we reach the end. */
11020 {
11025 }
11027 }
11029 /* True if PARM was found by a previous call to find_in. PARM can be a
11030 TREE_LIST, a DECL_TEMPLATE_PARM_P, or a TEMPLATE_PARM_P. */
11032 bool
11034 {
11039 else
11043 }
11045 /* Returns a list of unique template parameters found within T, where CTX_PARMS
11046 are the template parameters in scope. */
11048 tree
11050 {
11057 }
11059 /* Returns true if T depends on any template parameter. */
11061 bool
11063 {
11067 /* Namespaces can't depend on any template parameters. */
11083 else
11085 }
11087 /* Returns true if T depends on any template parameter with level LEVEL. */
11089 bool
11091 {
11094 }
11096 /* Returns true if the signature of DECL depends on any template parameter from
11097 its enclosing class. */
11099 static bool
11101 {
11105 else
11114 {
11117 {
11122 template_parm_outer_level,
11132 }
11133 }
11137 }
11139 /* Returns true if the constraints of DECL depend on any template parameters
11140 from its enclosing scope. */
11142 bool
11144 {
11151 {
11154 else
11156 }
11162 }
11164 /* Returns TRUE iff INST is an instantiation we don't need to do in an
11165 ill-formed translation unit, i.e. a variable or function that isn't
11166 usable in a constant expression. */
11170 {
11176 }
11178 /* Returns TRUE iff we should refuse to instantiate DECL because it's
11179 neglectable and instantiated from within an erroneous instantiation. */
11181 static bool
11183 {
11189 /* Avoid instantiating members of an ill-formed class. */
11190 bool refuse
11195 {
11200 }
11203 {
11204 /* Don't warn about it not being defined. */
11206 tree clone;
11209 }
11211 }
11219 /* We're starting to instantiate D; record the template instantiation context
11220 at LOC for diagnostics and to restore it later. */
11222 bool
11224 {
11228 {
11229 /* Tell error.cc not to try to instantiate any templates. */
11232 "template instantiation depth exceeds maximum of %d"
11234 max_tinst_depth);
11236 }
11238 /* If the current instantiation caused problems, don't let it instantiate
11239 anything else. Do allow deduction substitution and decls usable in
11240 constant expressions. */
11242 {
11243 /* Avoid no_linkage_errors and unused function (and all other)
11244 warnings for this decl. */
11247 }
11249 /* When not -quiet, dump template instantiations other than functions, since
11250 announce_function will take care of those. */
11272 }
11274 /* We're starting substitution of TMPL<ARGS>; record the template
11275 substitution context for diagnostics and to restore it later. */
11277 bool
11279 {
11281 }
11283 /* We're starting to instantiate D; record INPUT_LOCATION and the
11284 template instantiation context for diagnostics and to restore it
11285 later. */
11287 bool
11289 {
11291 }
11293 /* Likewise, but record LOC as the program location. */
11295 bool
11297 {
11300 }
11302 /* We're done instantiating this template; return to the instantiation
11303 context. */
11305 void
11307 {
11308 /* Restore the filename and line number stashed away when we started
11309 this instantiation. */
11313 }
11315 /* We're instantiating a deferred template; restore the template
11316 instantiation context in which the instantiation was requested, which
11317 is one step out from LEVEL. Return the corresponding DECL or TYPE. */
11319 static tree
11321 {
11333 }
11335 /* Returns the TINST_LEVEL which gives the original instantiation
11336 context. */
11340 {
11346 }
11348 /* True iff T is a friend function declaration that is not itself a template
11349 and is not defined in a class template. */
11351 bool
11353 {
11356 {
11360 /* DECL_FRIEND_CONTEXT is set for a friend defined in class. */
11363 /* Non-templated friends in a class template are still represented with a
11364 TEMPLATE_DECL; check that its primary template is the befriending
11365 class. Note that DECL_PRIMARY_TEMPLATE is null for
11366 template <class T> friend A<T>::f(); */
11370 }
11371 else
11373 }
11375 /* DECL is a friend FUNCTION_DECL or TEMPLATE_DECL. ARGS is the
11376 vector of template arguments, as for tsubst.
11378 Returns an appropriate tsubst'd friend declaration. */
11380 static tree
11382 {
11383 tree new_friend;
11388 /* This was a friend declared with an explicit template
11389 argument list, e.g.:
11391 friend void f<>(T);
11393 to indicate that f was a template instantiation, not a new
11394 function declaration. Now, we have to figure out what
11395 instantiation of what template. */
11396 {
11398 tree new_args;
11399 tree tmpl;
11402 /* Friend functions are looked up in the containing namespace scope.
11403 We must enter that scope, to avoid finding member functions of the
11404 current class with same name. */
11418 tsk_none);
11420 }
11426 /* The NEW_FRIEND will look like an instantiation, to the
11427 compiler, but is not an instantiation from the point of view of
11428 the language. For example, we might have had:
11430 template <class T> struct S {
11431 template <class U> friend void f(T, U);
11432 };
11434 Then, in S<int>, template <class U> void f(int, U) is not an
11435 instantiation of anything. */
11439 {
11445 /* Substitute TEMPLATE_PARMS_CONSTRAINTS so that parameter levels will
11446 match in decls_match. */
11451 {
11453 /* As well as each TEMPLATE_PARM_CONSTRAINTS. */
11455 tf_warning_or_error);
11456 }
11457 }
11459 /* The mangled name for the NEW_FRIEND is incorrect. The function
11460 is not a template instantiation and should not be mangled like
11461 one. Therefore, we forget the mangling here; we'll recompute it
11462 later if we need it. */
11464 {
11467 }
11470 {
11471 tree old_decl;
11472 tree ns;
11474 /* We must save some information from NEW_FRIEND before calling
11475 duplicate decls since that function will free NEW_FRIEND if
11476 possible. */
11480 (new_friend_template_info
11487 {
11488 /* This declaration is a `primary' template. */
11493 }
11495 /* Inside pushdecl_namespace_level, we will push into the
11496 current namespace. However, the friend function should go
11497 into the namespace of the template. */
11507 {
11508 /* This new friend declaration matched an existing
11509 declaration. For example, given:
11511 template <class T> void f(T);
11512 template <class U> class C {
11513 template <class T> friend void f(T) {}
11514 };
11516 the friend declaration actually provides the definition
11517 of `f', once C has been instantiated for some type. So,
11518 old_decl will be the out-of-class template declaration,
11519 while new_friend is the in-class definition.
11521 But, if `f' was called before this point, the
11522 instantiation of `f' will have DECL_TI_ARGS corresponding
11523 to `T' but not to `U', references to which might appear
11524 in the definition of `f'. Previously, the most general
11525 template for an instantiation of `f' was the out-of-class
11526 version; now it is the in-class version. Therefore, we
11527 run through all specialization of `f', adding to their
11528 DECL_TI_ARGS appropriately. In particular, they need a
11529 new set of outer arguments, corresponding to the
11530 arguments for this class instantiation.
11532 The same situation can arise with something like this:
11534 friend void f(int);
11535 template <class T> class C {
11536 friend void f(T) {}
11537 };
11539 when `C<int>' is instantiated. Now, `f(int)' is defined
11540 in the class. */
11543 /* On the other hand, if the in-class declaration does
11544 *not* provide a definition, then we don't want to alter
11545 existing definitions. We can just leave everything
11546 alone. */
11547 ;
11548 else
11549 {
11553 /* Overwrite whatever template info was there before, if
11554 any, with the new template information pertaining to
11555 the declaration. */
11559 {
11560 /* We should have called reregister_specialization in
11561 duplicate_decls. */
11566 /* Instantiate it if the global has already been used. */
11570 }
11571 else
11572 {
11573 tree t;
11575 /* Indicate that the old function template is a partial
11576 instantiation. */
11584 /* Reassign any specializations already in the hash table
11585 to the new more general template, and add the
11586 additional template args. */
11590 {
11592 spec_entry elt;
11604 register_specialization
11607 }
11609 }
11610 }
11612 /* The information from NEW_FRIEND has been merged into OLD_DECL
11613 by duplicate_decls. */
11615 }
11617 /* We've just introduced a namespace-scope function in the purview
11618 without necessarily having opened the enclosing namespace, so
11619 make sure the namespace is in the purview now too. */
11624 }
11625 else
11626 {
11630 /* In the code
11631 template <class T> class C {
11632 template <class U> friend void C1<U>::f (); // case 1
11633 friend void C2<T>::f (); // case 2
11634 };
11635 we only need to make sure CONTEXT is a complete type for
11636 case 2. To distinguish between the two cases, we note that
11637 CONTEXT of case 1 remains dependent type after tsubst while
11638 this isn't true for case 2. */
11648 {
11650 /* do_friend adds the TEMPLATE_DECL for any member friend
11651 template even if it isn't a member template, i.e.
11652 template <class T> friend A<T>::f();
11653 Look through it in that case. */
11657 /* Check to see that the declaration is really present, and,
11658 possibly obtain an improved declaration. */
11663 }
11664 }
11667 }
11669 /* FRIEND_TMPL is a friend TEMPLATE_DECL. ARGS is the vector of
11670 template arguments, as for tsubst.
11672 Returns an appropriate tsubst'd friend type or error_mark_node on
11673 failure. */
11675 static tree
11677 {
11678 tree tmpl;
11681 {
11684 }
11689 else
11690 {
11693 }
11699 {
11700 /* The friend template has already been declared. Just
11701 check to see that the declarations match, and install any new
11702 default parameters. We must tsubst the default parameters,
11703 of course. We only need the innermost template parameters
11704 because that is all that redeclare_class_template will look
11705 at. */
11708 {
11712 tf_warning_or_error);
11722 }
11723 }
11724 else
11725 {
11726 /* The friend template has not already been declared. In this
11727 case, the instantiation of the template class will cause the
11728 injection of this template into the namespace scope. */
11732 {
11733 /* The new TMPL is not an instantiation of anything, so we
11734 forget its origins. We don't reset CLASSTYPE_TI_TEMPLATE
11735 for the new type because that is supposed to be the
11736 corresponding template decl, i.e., TMPL. */
11743 /* Substitute into and set the constraints on the new declaration. */
11745 {
11753 }
11755 /* Inject this template into the enclosing namspace scope. */
11757 }
11758 }
11762 else
11766 }
11768 /* Returns zero if TYPE cannot be completed later due to circularity.
11769 Otherwise returns one. */
11771 static int
11773 {
11783 else
11785 }
11790 /* Instantiate the contract statement. */
11792 static tree
11794 tree in_decl)
11795 {
11801 /* Rebuild the result variable. */
11803 {
11811 /* Make sure the postcondition is valid. */
11817 /* Make the variable available for lookup. */
11819 }
11821 /* Instantiate the condition. If the return type is undeduced, process
11822 the expression as if inside a template to avoid spurious type errors. */
11832 /* And the comment. */
11837 }
11839 /* Update T by instantiating its contract attribute. */
11841 static void
11844 {
11845 /* For non-specializations, adjust the current declaration to the most general
11846 version of in_decl. Because we defer the instantiation of contracts as long
11847 as possible, they are still written in terms of the parameters (and return
11848 type) of the most general template. */
11855 /* Get the contract to be instantiated. */
11858 /* Use the complete set of template arguments for instantiation. The
11859 contract may not have been instantiated and still refer to outer levels
11860 of template parameters. */
11863 /* For member functions, make this available for semantic analysis. */
11867 {
11871 }
11878 /* Rebuild the attribute. */
11880 }
11882 /* Rebuild the attribute list for DECL, substituting into contracts
11883 as needed. */
11885 void
11887 {
11890 {
11893 }
11895 }
11897 /* Instantiate a single dependent attribute T (a TREE_LIST), and return either
11898 T or a new TREE_LIST, possibly a chain in the case of a pack expansion. */
11900 static tree
11903 {
11906 /* Note that contract attributes are never substituted from this function.
11907 Their instantiation is triggered by regenerate_from_template_decl when
11908 we instantiate the body of the function. */
11916 {
11923 clauses
11927 else
11929 }
11933 {
11941 {
11946 {
11949 /* FIXME: The body of this loop should really be dispatching
11950 according to omp_ts_map[OMP_TS_CODE (TS)].tp_type instead
11951 of having hard-wired knowledge of specific selectors. */
11954 {
11962 }
11963 else
11964 {
11967 {
11972 {
11973 location_t loc
11975 match_loc);
11979 }
11981 {
11982 location_t loc
11984 match_loc);
11988 }
11990 }
11996 {
11997 bool allow_string
12007 {
12008 location_t loc
12010 match_loc);
12013 "integer expression or string "
12015 else
12019 }
12021 }
12022 }
12025 }
12027 }
12029 }
12030 /* If the first attribute argument is an identifier, don't
12031 pass it through tsubst. Attributes like mode, format,
12032 cleanup and several target specific attributes expect it
12033 unmodified. */
12035 {
12036 tree chain
12040 }
12042 {
12043 /* An attribute pack expansion. */
12052 {
12056 }
12058 }
12059 else
12067 }
12069 /* Instantiate any dependent attributes in ATTRIBUTES, returning either it
12070 unchanged or a new TREE_LIST chain. */
12072 static tree
12075 {
12080 {
12084 }
12088 {
12091 {
12094 {
12100 }
12101 }
12103 }
12106 }
12108 /* Apply any attributes which had to be deferred until instantiation
12109 time. DECL_P, ATTRIBUTES and ATTR_FLAGS are as cplus_decl_attributes;
12110 ARGS, COMPLAIN, IN_DECL are as tsubst. Returns true normally,
12111 false on error. */
12113 static bool
12116 {
12117 tree t;
12124 {
12128 /* DECL_ATTRIBUTES comes from copy_node in tsubst_decl, and is identical
12129 to our attributes parameter. */
12131 }
12132 else
12133 {
12135 /* TYPE_ATTRIBUTES was set up (with abi_tag and may_alias) in
12136 lookup_template_class_1, and should be preserved. */
12140 }
12142 /* save_template_attributes puts the dependent attributes at the beginning of
12143 the list; find the non-dependent ones. */
12149 /* Apply any non-dependent attributes. */
12155 /* And then any dependent ones. */
12159 {
12164 {
12167 }
12170 }
12172 /* cplus_decl_attributes can add some attributes implicitly. For templates,
12173 those attributes should have been added already when those templates were
12174 parsed, and shouldn't be added based on from which context they are
12175 first time instantiated. */
12178 optimization_default_node);
12181 NULL);
12187 }
12189 /* The template TMPL is being instantiated with the template arguments TARGS.
12190 Perform the access checks that we deferred when parsing the template. */
12192 static void
12194 {
12204 {
12212 /* Make access check error messages point to the location
12213 of the use of the typedef. */
12217 }
12218 }
12220 tree
12222 {
12226 tree typedecl;
12227 tree pbinfo;
12228 tree base_list;
12230 tree fn_context;
12239 /* Figure out which template is being instantiated. */
12243 /* Mark the type as in the process of being defined. */
12246 /* We may be in the middle of deferred access check. Disable
12247 it now. */
12250 /* Determine what specialization of the original template to
12251 instantiate. */
12256 {
12257 /* This TYPE is actually an instantiation of a partial
12258 specialization. We replace the innermost set of ARGS with
12259 the arguments appropriate for substitution. For example,
12260 given:
12262 template <class T> struct S {};
12263 template <class T> struct S<T*> {};
12265 and supposing that we are instantiating S<int*>, ARGS will
12266 presently be {int*} -- but we need {int}. */
12269 }
12270 else
12271 {
12274 }
12276 /* If the template we're instantiating is incomplete, then clearly
12277 there's nothing we can do. */
12279 {
12280 /* We can try again later. */
12283 }
12285 /* If we've recursively instantiated too many templates, stop. */
12293 /* Also avoid push_to_top_level for a lambda in an NSDMI. */
12298 else
12299 {
12302 }
12306 /* Use #pragma pack from the template context. */
12312 /* Set the input location to the most specialized template definition.
12313 This is needed if tsubsting causes an error. */
12327 {
12330 /* Adjust visibility for template arguments. */
12332 }
12338 /* We should never instantiate a nested class before its enclosing
12339 class; we need to look up the nested class by name before we can
12340 instantiate it, and that lookup should instantiate the enclosing
12341 class. */
12346 /* Defer access checking while we substitute into the types named in
12347 the base-clause. */
12350 {
12351 tree pbase_binfo;
12354 /* Substitute into each of the bases to determine the actual
12355 basetypes. */
12357 {
12358 tree base;
12364 {
12365 expanded_bases =
12372 }
12375 {
12377 /* Extract the already-expanded base class. */
12379 else
12380 /* Substitute to figure out the base class. */
12382 NULL_TREE);
12390 }
12391 }
12393 /* The list is now in reverse order; correct that. */
12395 }
12396 /* Now call xref_basetypes to set up all the base-class
12397 information. */
12405 /* Now that our base classes are set up, enter the scope of the
12406 class, so that name lookups into base classes, etc. will work
12407 correctly. This is precisely analogous to what we do in
12408 begin_class_definition when defining an ordinary non-template
12409 class, except we also need to push the enclosing classes. */
12412 /* Now check accessibility of the types named in its base-clause,
12413 relative to the scope of the class. */
12416 /* A vector to hold members marked with attribute used. */
12419 /* Now members are processed in the order of declaration. */
12422 {
12426 {
12428 {
12430 /* A closure type for a lambda in an NSDMI or default argument.
12431 Ignore it; it will be regenerated when needed. */
12434 /* If the member is a class template, we've
12435 already substituted its type. */
12445 {
12448 /* Now, install the tag. We don't use pushtag
12449 because that does too much work -- creating an
12450 implicit typedef, which we've already done. */
12455 }
12456 }
12458 {
12459 tree r;
12469 /* Instantiate members marked with attribute used. */
12475 }
12478 /* A closure type for a lambda in an NSDMI or default argument.
12480 else
12481 {
12482 /* Build new TYPE_FIELDS. */
12486 {
12487 tree r;
12492 /* The file and line for this declaration, to
12493 assist in error message reporting. Since we
12494 called push_tinst_level above, we don't need to
12495 restore these. */
12505 {
12506 /* A capture pack became multiple fields. */
12509 }
12512 {
12516 {
12517 /* In [temp.inst]:
12519 [t]he initialization (and any associated
12520 side-effects) of a static data member does
12521 not occur unless the static data member is
12522 itself used in a way that requires the
12523 definition of the static data member to
12524 exist.
12526 Therefore, we do not substitute into the
12527 initialized for the static data member here. */
12528 finish_static_data_member_decl
12534 /* Instantiate members marked with attribute used. */
12537 }
12539 {
12540 /* Determine whether R has a valid type and can be
12541 completed later. If R is invalid, then its type
12542 is replaced by error_mark_node. */
12548 {
12549 /* If R's type couldn't be completed and
12550 it isn't a flexible array member (whose
12551 type is incomplete by definition) give
12552 an error. */
12555 }
12560 {
12563 }
12567 }
12569 /* If it is a TYPE_DECL for a class-scoped
12570 ENUMERAL_TYPE, such a thing will already have
12571 been added to the field list by tsubst_enum
12572 in finish_member_declaration case above. */
12576 {
12579 }
12580 }
12581 }
12582 }
12583 }
12584 else
12585 {
12588 {
12589 /* Build new CLASSTYPE_FRIEND_CLASSES. */
12593 {
12594 /* template <class T> friend class C; */
12596 }
12598 {
12599 /* template <class T> friend class C::D; */
12604 }
12607 {
12608 /* This could be either
12610 friend class T::C;
12612 when dependent_type_p is false or
12614 template <class U> friend class T::C;
12616 otherwise. */
12617 /* Bump processing_template_decl in case this is something like
12618 template <class T> friend struct A<T>::B. */
12623 }
12625 /* friend class C<T>; */
12629 /* Otherwise it's
12631 friend class C;
12633 where C is already declared or
12635 friend class C<int>;
12637 We don't have to do anything in these cases. */
12641 }
12642 else
12643 {
12644 /* Build new DECL_FRIENDLIST. */
12645 tree r;
12647 /* The file and line for this declaration, to
12648 assist in error message reporting. Since we
12649 called push_tinst_level above, we don't need to
12650 restore these. */
12654 {
12657 }
12662 {
12665 }
12666 }
12667 }
12668 }
12671 {
12672 /* Restore these before substituting into the lambda capture
12673 initializers. */
12676 }
12678 /* Set the file and line number information to whatever is given for
12679 the class itself. This puts error messages involving generated
12680 implicit functions at a predictable point, and the same point
12681 that would be used for non-template classes. */
12688 /* Remember if instantiating this class ran into errors, so we can avoid
12689 instantiating member functions in limit_bad_template_recursion. We set
12690 this flag even if the problem was in another instantiation triggered by
12691 this one, as that will likely also cause trouble for member functions. */
12695 /* We don't instantiate default arguments for member functions. 14.7.1:
12697 The implicit instantiation of a class template specialization causes
12698 the implicit instantiation of the declarations, but not of the
12699 definitions or default arguments, of the class member functions,
12700 member classes, static data members and member templates.... */
12705 /* Now that we've gone through all the members, instantiate those
12706 marked with attribute used. We must do this in the context of
12707 the class -- not the context we pushed from, as that might be
12708 inside a template and change the behaviour of mark_used. */
12718 /* The vtable for a template class can be emitted in any translation
12719 unit in which the class is instantiated. When there is no key
12720 method, however, finish_struct_1 will already have added TYPE to
12721 the keyed_classes. */
12726 }
12728 tree
12730 {
12731 tree r;
12737 else
12738 {
12744 }
12747 }
12749 /* Given a function parameter pack TMPL_PARM and some function parameters
12750 instantiated from it at *SPEC_P, return a NONTYPE_ARGUMENT_PACK of them
12751 and set *SPEC_P to point at the next point in the list. */
12753 tree
12755 {
12756 /* Collect all of the extra "packed" parameters into an
12757 argument pack. */
12758 tree argpack;
12769 {
12770 /* The instantiation is still a parameter pack; don't wrap it in a
12771 NONTYPE_ARGUMENT_PACK. */
12774 }
12775 else
12776 {
12777 /* Fill in PARMVEC with all of the parameters. */
12781 {
12787 }
12789 /* Build the argument packs. */
12791 }
12795 }
12797 /* Give a chain SPEC_PARM of PARM_DECLs, pack them into a
12798 NONTYPE_ARGUMENT_PACK. */
12800 static tree
12802 {
12804 }
12806 /* Return 1 if the Ith element of the argument pack ARG_PACK is a
12807 pack expansion with no extra args, 2 if it has extra args, or 0
12808 if it is not a pack expansion. */
12810 static int
12812 {
12814 /* We're being called before this happens in tsubst_pack_expansion. */
12821 /* A decl pack is itself an expansion. */
12828 }
12831 /* Creates and return an ARGUMENT_PACK_SELECT tree node. */
12833 static tree
12835 {
12842 }
12844 /* This is a subroutine of tsubst_pack_expansion.
12846 It returns TRUE if we need to use the PACK_EXPANSION_EXTRA_ARGS
12847 mechanism to store the (non complete list of) arguments of the
12848 substitution and return a non substituted pack expansion, in order
12849 to wait for when we have enough arguments to really perform the
12850 substitution. */
12852 static bool
12854 tree parm_packs,
12857 {
12862 /* If one pack has an expansion and another pack has a normal
12863 argument or if one pack has an empty argument and an another
12864 one hasn't then tsubst_pack_expansion cannot perform the
12865 substitution and need to fall back on the
12866 PACK_EXPANSION_EXTRA mechanism. */
12870 {
12871 /* If all the actual packs are pack expansions, we can still
12872 subsitute directly. */
12874 {
12884 }
12886 }
12889 {
12893 parm_pack;
12895 {
12900 /* We can't substitute a pack expansion with extra args into
12901 our pattern. */
12905 else
12907 }
12910 {
12913 }
12914 }
12916 }
12918 /* [temp.variadic]/6 says that:
12920 The instantiation of a pack expansion [...]
12921 produces a list E1,E2, ..., En, where N is the number of elements
12922 in the pack expansion parameters.
12924 This subroutine of tsubst_pack_expansion produces one of these Ei.
12926 PATTERN is the pattern of the pack expansion. PARM_PACKS is a
12927 TREE_LIST in which each TREE_PURPOSE is a parameter pack of
12928 PATTERN, and each TREE_VALUE is its corresponding argument pack.
12929 INDEX is the index 'i' of the element Ei to produce. ARGS,
12930 COMPLAIN, and IN_DECL are the same parameters as for the
12931 tsubst_pack_expansion function.
12933 The function returns the resulting Ei upon successful completion,
12934 or error_mark_node.
12936 Note that this function possibly modifies the ARGS parameter, so
12937 it's the responsibility of the caller to restore it. */
12939 static tree
12941 tree parm_packs,
12943 tree args /* This parm gets
12945 tsubst_flags_t complain,
12946 tree in_decl)
12947 {
12948 tree t;
12951 /* For each parameter pack, change the substitution of the parameter
12952 pack to the ith argument in its argument pack, then expand the
12953 pattern. */
12955 {
12960 ith_elem_is_expansion |=
12963 /* Select the Ith argument from the pack. */
12967 {
12969 {
12974 }
12975 else
12977 }
12978 else
12979 {
12984 {
12986 /* Update the corresponding argument. */
12988 }
12989 else
12990 /* Re-use the ARGUMENT_PACK_SELECT. */
12992 }
12994 }
12996 /* Substitute into the PATTERN with the (possibly altered)
12997 arguments. */
12999 /* Expanding a fixed parameter pack from
13000 coerce_template_parameter_pack. */
13006 else
13007 {
13010 /* When expanding the fake auto... pack expansion from add_capture, we
13011 need to mark that the expansion is no longer a pack. */
13013 }
13015 /* If the Ith argument pack element is a pack expansion, then
13016 the Ith element resulting from the substituting is going to
13017 be a pack expansion as well. */
13022 }
13024 /* When the unexpanded parameter pack in a fold expression expands to an empty
13025 sequence, the value of the expression is as follows; the program is
13026 ill-formed if the operator is not listed in this table.
13028 && true
13029 || false
13030 , void() */
13032 tree
13034 {
13038 {
13047 }
13053 }
13055 /* Given a fold-expression T and a current LEFT and RIGHT operand,
13056 form an expression that combines the two terms using the
13057 operator of T. */
13059 static tree
13061 {
13066 // Handle compound assignment operators.
13073 {
13082 complain);
13083 }
13084 }
13086 /* Substitute ARGS into the pack of a fold expression T. */
13090 {
13092 }
13094 /* Substitute ARGS into the pack of a fold expression T. */
13098 {
13100 }
13102 /* Expand a PACK of arguments into a grouped as left fold.
13103 Given a pack containing elements A0, A1, ..., An and an
13104 operator @, this builds the expression:
13106 ((A0 @ A1) @ A2) ... @ An
13108 Note that PACK must not be empty.
13110 The operator is defined by the original fold expression T. */
13112 static tree
13114 {
13117 {
13120 }
13122 }
13124 /* Substitute into a unary left fold expression. */
13126 static tree
13128 tree in_decl)
13129 {
13134 {
13138 }
13141 else
13143 }
13145 /* Substitute into a binary left fold expression.
13147 Do ths by building a single (non-empty) vector of argumnts and
13148 building the expression from those elements. */
13150 static tree
13152 tree in_decl)
13153 {
13162 {
13167 }
13175 }
13177 /* Expand a PACK of arguments into a grouped as right fold.
13178 Given a pack containing elementns A0, A1, ..., and an
13179 operator @, this builds the expression:
13181 A0@ ... (An-2 @ (An-1 @ An))
13183 Note that PACK must not be empty.
13185 The operator is defined by the original fold expression T. */
13187 tree
13189 {
13190 // Build the expression.
13194 {
13197 }
13199 }
13201 /* Substitute into a unary right fold expression. */
13203 static tree
13205 tree in_decl)
13206 {
13211 {
13215 }
13218 else
13220 }
13222 /* Substitute into a binary right fold expression.
13224 Do ths by building a single (non-empty) vector of arguments and
13225 building the expression from those elements. */
13227 static tree
13229 tree in_decl)
13230 {
13239 {
13244 }
13253 }
13255 /* Walk through the pattern of a pack expansion, adding everything in
13256 local_specializations to a list. */
13258 class el_data
13259 {
13261 /* Set of variables declared within the pattern. */
13263 /* Set of AST nodes that have been visited by the traversal. */
13265 /* List of local_specializations used within the pattern. */
13266 tree extra;
13267 tsubst_flags_t complain;
13268 /* True iff we don't want to walk into unevaluated contexts. */
13270 /* The unevaluated contexts that we avoided walking. */
13275 };
13276 static tree
13278 {
13285 {
13289 }
13292 /* Remember local typedefs (85214). */
13296 {
13302 {
13305 decl2
13311 {
13314 }
13315 }
13316 }
13318 {
13319 /* Since we defer implicit capture, look in the parms and body. */
13325 }
13327 {
13329 /* Don't mess with variables declared within the pattern. */
13332 {
13333 /* Maybe pull out the PARM_DECL for a partial instantiation. */
13336 {
13342 }
13344 {
13345 /* Handle lambda capture here, since we aren't doing any
13346 substitution now, and so tsubst_copy won't call
13347 process_outer_var_ref. */
13351 {
13357 {
13358 /* Make a new NONTYPE_ARGUMENT_PACK of the capture
13359 proxies. */
13361 {
13366 }
13368 }
13369 }
13370 }
13371 }
13375 }
13377 }
13378 static tree
13380 {
13382 /* Walk the pattern twice, ignoring unevaluated operands the first time
13383 around, so that if a local specialization appears in both an evaluated
13384 and unevaluated context we prefer to process it in the evaluated context
13385 (since e.g. process_outer_var_ref is a no-op inside an unevaluated
13386 context). */
13389 /* Now walk the unevaluated contexts we skipped the first time around. */
13392 {
13395 }
13397 }
13399 /* Extract any uses of local_specializations from PATTERN and add them to ARGS
13400 for use in PACK_EXPANSION_EXTRA_ARGS. */
13402 tree
13404 {
13405 /* Make a copy of the extra arguments so that they won't get changed
13406 out from under us. */
13412 }
13414 /* Apply any local specializations from PACK_EXPANSION_EXTRA_ARGS and add the
13415 normal template args to ARGS. */
13417 tree
13419 {
13421 {
13423 {
13424 /* The partial instantiation involved local declarations collected in
13425 extract_local_specs; map from the general template to our local
13426 context. */
13432 /* else inst is already a full instantiation of the pack. */
13434 }
13437 }
13439 {
13440 /* This can happen after dependent substitution into a
13441 requires-expr or a lambda that uses constexpr if. */
13444 }
13445 else
13448 }
13450 /* Substitute ARGS into T, which is an pack expansion
13451 (i.e. TYPE_PACK_EXPANSION or EXPR_PACK_EXPANSION). Returns a
13452 TREE_VEC with the substituted arguments, a PACK_EXPANSION_* node
13453 (if only a partial substitution could be performed) or
13454 ERROR_MARK_NODE if there was an error. */
13455 tree
13457 tree in_decl)
13458 {
13459 tree pattern;
13463 tree result;
13470 /* Add in any args remembered from an earlier partial instantiation. */
13475 /* Determine the argument packs that will instantiate the parameter
13476 packs used in the expansion expression. While we're at it,
13477 compute the number of arguments to be expanded and make sure it
13478 is consistent. */
13481 {
13488 {
13493 else
13495 }
13497 {
13499 {
13502 parm_pack);
13504 }
13507 }
13509 {
13510 /* We know we have correct local_specializations if this
13511 expansion is at function scope, or if we're dealing with a
13512 local parameter in a requires expression; for the latter,
13513 tsubst_requires_expr set it up appropriately. */
13516 else
13517 /* We can't rely on local_specializations for a parameter
13518 name used later in a function declaration (such as in a
13519 late-specified return type). Even if it exists, it might
13520 have the wrong value for a recursive call. */
13524 {
13525 /* This parameter pack was used in an unevaluated context. Just
13526 make a dummy decl, since it's only used for its type. */
13531 /* Partial instantiation of the parm_pack, we can't build
13532 up an argument pack yet. */
13534 else
13536 }
13538 /* This argument pack isn't fully instantiated yet. */
13540 }
13542 {
13546 }
13547 else
13548 {
13557 }
13564 /* This can only happen if we forget to expand an argument
13565 pack somewhere else. Just return an error, silently. */
13566 {
13570 }
13573 {
13577 /* Don't bother trying to do a partial substitution with
13578 incomplete packs; we'll try again after deduction. */
13585 {
13590 pattern);
13591 else
13593 pattern);
13595 }
13597 /* Keep track of the parameter packs and their corresponding
13598 argument packs. */
13601 }
13602 else
13603 {
13604 /* We can't substitute for this parameter pack. We use a flag as
13605 well as the missing_level counter because function parameter
13606 packs don't have a level. */
13609 }
13610 }
13612 /* If the expansion is just T..., return the matching argument pack, unless
13613 we need to call convert_from_reference on all the elements. This is an
13614 important optimization; see c++/68422. */
13617 {
13620 /* If the argument pack is a single pack expansion, pull it out. */
13623 {
13627 /* Except if this isn't a simple sizeof...(T) which gets sZ
13629 else
13631 }
13633 /* Types need no adjustment, nor does sizeof..., and if we still have
13634 some pack expansion args we won't do anything yet. */
13639 /* Also optimize expression pack expansions if we can tell that the
13640 elements won't have reference type. */
13646 /* Otherwise use the normal path so we get convert_from_reference. */
13647 }
13649 /* We cannot expand this expansion expression, because we don't have
13650 all of the argument packs we need. */
13652 {
13653 /* We got some full packs, but we can't substitute them in until we
13654 have values for all the packs. So remember these until then. */
13660 }
13662 /* If NEED_LOCAL_SPECIALIZATIONS then we're in a late-specified return
13663 type, so create our own local specializations map; the current map is
13664 either NULL or (in the case of recursive unification) might have
13665 bindings that we don't want to use or alter. */
13670 {
13671 /* There were no real arguments, we're just replacing a parameter
13672 pack with another version of itself. Substitute into the
13673 pattern and return a PACK_EXPANSION_*. The caller will need to
13674 deal with that. */
13677 else
13683 {
13684 /* This is a fake auto... pack expansion created in add_capture with
13685 _PACKS that don't appear in the pattern. Copy one over. */
13692 }
13694 }
13698 /* For each argument in each argument pack, substitute into the
13699 pattern. */
13703 {
13705 i,
13707 in_decl);
13710 {
13713 }
13714 }
13716 /* Update ARGS to restore the substitution from parameter packs to
13717 their argument packs. */
13719 {
13726 else
13727 {
13735 /* Update the corresponding argument. */
13739 else
13741 }
13742 }
13744 /* If the dependent pack arguments were such that we end up with only a
13745 single pack expansion again, there's no need to keep it in a TREE_VEC. */
13751 }
13753 /* Make an argument pack out of the TREE_VEC VEC. */
13755 static tree
13757 {
13758 tree pack;
13762 else
13763 {
13766 }
13769 }
13771 /* Return an exact copy of template args T that can be modified
13772 independently. */
13774 static tree
13776 {
13784 {
13789 }
13795 }
13797 /* Substitute ARGS into the *_ARGUMENT_PACK orig_arg. */
13799 tree
13801 tree in_decl)
13802 {
13803 /* This flag is used only during deduction, and we don't expect to
13804 substitute such ARGUMENT_PACKs. */
13807 /* Substitute into each of the arguments. */
13816 /* If we're substituting into a generic ARGUMENT_PACK for a variadic
13817 template parameter, we might be able to avoid allocating a new
13818 ARGUMENT_PACK and reuse the corresponding ARGUMENT_PACK from ARGS
13819 if the substituted result is identical to it. */
13821 {
13828 {
13831 }
13832 }
13834 tree new_arg;
13836 {
13839 }
13840 else
13841 {
13844 }
13847 }
13849 /* Substitute ARGS into the vector or list of template arguments T. */
13851 tree
13853 {
13857 /* In "sizeof(X<I>)" we need to evaluate "I". */
13858 cp_evaluated ev;
13864 /* True iff the substituted result is identical to T. */
13868 {
13870 tree new_arg;
13877 {
13878 /* Substitute into an expansion expression. */
13882 /* Add to the expanded length adjustment the number of
13883 expanded arguments. We subtract one from this
13884 measurement, because the argument pack expression
13885 itself is already counted as 1 in
13886 LEN. EXPANDED_LEN_ADJUST can actually be negative, if
13887 the argument pack is empty. */
13889 }
13892 else
13901 }
13908 /* If ARGS and T are both multi-level, the substituted result may be
13909 identical to ARGS. */
13914 /* If T appears to be a vector of generic template arguments, the
13915 substituted result may be identical to the corresponding level
13916 from ARGS. */
13918 {
13923 }
13925 /* If the substituted result is identical to MAYBE_REUSE, return
13926 it and avoid allocating a new TREE_VEC, as an optimization. */
13932 /* If T consists of only a pack expansion for which substitution yielded
13933 a TREE_VEC of the expanded elements, then reuse that TREE_VEC instead
13934 of effectively making a copy. */
13940 /* Make space for the expanded arguments coming from template
13941 argument packs. */
13943 /* T can contain TREE_VECs. That happens if T contains the
13944 arguments for a member template.
13945 In that case each TREE_VEC in T represents a level of template
13946 arguments, and T won't carry any non defaulted argument count.
13947 It will rather be the nested TREE_VECs that will carry one.
13948 In other words, T carries a non defaulted argument count only
13949 if it doesn't contain any nested TREE_VEC. */
13951 {
13955 }
13959 {
13964 {
13965 /* Now expand the template argument pack "in place". */
13968 }
13969 else
13970 {
13972 out++;
13973 }
13974 }
13978 }
13980 /* Substitute ARGS into one level PARMS of template parameters. */
13982 static tree
13984 {
13991 {
13999 }
14002 }
14004 /* Return the result of substituting ARGS into the template parameters
14005 given by PARMS. If there are m levels of ARGS and m + n levels of
14006 PARMS, then the result will contain n levels of PARMS. For
14007 example, if PARMS is `template <class T> template <class U>
14008 template <T*, U, class V>' and ARGS is {{int}, {double}} then the
14009 result will be `template <int*, double, class V>'. */
14011 static tree
14013 {
14017 /* When substituting into a template, we must set
14018 PROCESSING_TEMPLATE_DECL as the template parameters may be
14019 dependent if they are based on one-another, and the dependency
14020 predicates are short-circuit outside of templates. */
14027 {
14036 }
14041 }
14043 /* Return the result of substituting ARGS into one template parameter
14044 given by T. T Must be a TREE_LIST which TREE_VALUE is the template
14045 parameter and which TREE_PURPOSE is the default argument of the
14046 template parameter. */
14048 static tree
14050 {
14073 }
14075 /* Substitute in-place the TEMPLATE_PARM_CONSTRAINTS of each template
14076 parameter in PARMS for sake of declaration matching. */
14078 static void
14080 tsubst_flags_t complain)
14081 {
14084 {
14090 }
14092 }
14094 /* Substitute the ARGS into the indicated aggregate (or enumeration)
14095 type T. If T is not an aggregate or enumeration type, it is
14096 handled as if by tsubst. IN_DECL is as for tsubst. If
14097 ENTERING_SCOPE is nonzero, T is the context for a template which
14098 we are presently tsubst'ing. Return the substituted value. */
14100 static tree
14102 tree args,
14103 tsubst_flags_t complain,
14104 tree in_decl,
14106 {
14110 /* Handle typedefs via tsubst so that they get consistently reused. */
14112 {
14117 /* The effect of entering_scope is that for a dependent specialization
14118 A<T>, lookup_template_class prefers to return A's primary template
14119 type instead of the implicit instantiation. So when entering_scope,
14120 we mirror this behavior by inspecting TYPE_CANONICAL appropriately,
14121 taking advantage of the fact that lookup_template_class links the two
14122 types by setting TYPE_CANONICAL of the latter to the former. */
14131 }
14134 {
14142 }
14143 }
14145 /* The part of tsubst_aggr_type that's shared with the RECORD_, UNION_
14146 and ENUMERAL_TYPE cases of tsubst. */
14148 static tree
14150 tree args,
14151 tsubst_flags_t complain,
14152 tree in_decl,
14154 {
14156 {
14159 /* Figure out what arguments are appropriate for the
14160 type we are trying to find. For example, given:
14162 template <class T> struct S;
14163 template <class T, class U> void f(T, U) { S<U> su; }
14165 and supposing that we are instantiating f<int, double>,
14166 then our ARGS will be {int, double}, but, when looking up
14167 S we only want {double}. */
14176 }
14177 else
14178 /* This is not a template type, so there's nothing to do. */
14180 }
14182 /* Map from a FUNCTION_DECL to a vec of default argument instantiations,
14183 indexed in reverse order of the parameters. */
14187 /* Return a reference to the vec* of defarg insts for FN. */
14191 {
14195 tree_vec_map **slot
14198 {
14201 }
14203 }
14205 /* Substitute into the default argument ARG (a default argument for
14206 FN), which has the indicated TYPE. */
14208 tree
14210 tsubst_flags_t complain)
14211 {
14214 /* This can happen in invalid code. */
14218 /* Shortcut {}. */
14233 /* Remember the location of the pointer to the vec rather than the location
14234 of the particular element, in case the vec grows in tsubst_expr. */
14236 /* Index in reverse order to avoid allocating space for initial parameters
14237 that don't have default arguments. */
14244 /* This default argument came from a template. Instantiate the
14245 default argument here, not in tsubst. In the case of
14246 something like:
14248 template <class T>
14249 struct S {
14250 static T t();
14251 void f(T = t());
14252 };
14254 we must be careful to do name lookup in the scope of S<T>,
14255 rather than in the current class. */
14259 /* So in_immediate_context knows this is a default argument. */
14263 /* The default argument expression may cause implicitly defined
14264 member functions to be synthesized, which will result in garbage
14265 collection. We must treat this situation as if we were within
14266 the body of function so as to avoid collecting live data on the
14267 stack. */
14274 /* Make sure the default argument is reasonable. */
14291 }
14293 /* Substitute into all the default arguments for FN. */
14295 static void
14297 {
14298 tree arg;
14299 tree tmpl_args;
14303 /* If this function is not yet instantiated, we certainly don't need
14304 its default arguments. */
14307 /* Don't do this again for clones. */
14313 arg;
14319 complain);
14320 }
14322 /* Hash table mapping a FUNCTION_DECL to its dependent explicit-specifier. */
14325 /* Store a pair to EXPLICIT_SPECIFIER_MAP. */
14327 void
14329 {
14334 }
14336 /* Lookup an element in EXPLICIT_SPECIFIER_MAP. */
14338 tree
14340 {
14342 }
14344 /* Given T, a FUNCTION_TYPE or METHOD_TYPE, construct and return a corresponding
14345 FUNCTION_TYPE or METHOD_TYPE whose return type is RETURN_TYPE, argument types
14346 are ARG_TYPES, and exception specification is RAISES, and otherwise is
14347 identical to T. */
14349 static tree
14352 {
14355 tree new_type;
14357 {
14360 }
14361 else
14362 {
14364 /* Don't pick up extra function qualifiers from the basetype. */
14367 {
14368 /* [temp.deduct]
14370 Type deduction may fail for any of the following
14371 reasons:
14373 -- Attempting to create "pointer to member of T" when T
14374 is not a class type. */
14377 r);
14379 }
14383 }
14389 }
14391 /* Check if the function type of DECL, a FUNCTION_DECL, agrees with the type of
14392 each of its formal parameters. If there is a disagreement then rebuild
14393 DECL's function type according to its formal parameter types, as part of a
14394 resolution for Core issues 1001/1322. */
14396 static void
14398 {
14401 {
14404 {
14408 {
14411 }
14415 }
14416 }
14427 {
14432 }
14434 {
14444 }
14452 }
14454 /* Subroutine of tsubst_decl for the case when T is a FUNCTION_DECL. */
14456 static tree
14459 {
14464 /* Nobody should be tsubst'ing into non-template functions. */
14469 {
14472 }
14474 {
14475 /* If T is not dependent, just return it. */
14480 /* A non-templated friend doesn't get DECL_TEMPLATE_INFO. */
14484 /* Calculate the most general template of which R is a
14485 specialization. */
14488 /* We're substituting a lambda function under tsubst_lambda_expr but not
14489 directly from it; find the matching function we're already inside.
14490 But don't do this if T is a generic lambda with a single level of
14491 template parms, as in that case we're doing a normal instantiation. */
14497 /* Calculate the complete set of arguments used to
14498 specialize R. */
14500 {
14502 (DECL_TEMPLATE_RESULT
14508 /* Check to see if we already have this specialization. */
14511 /* The spec for these args might be a partial instantiation of the
14512 template, but here what we want is the FUNCTION_DECL. */
14514 }
14515 else
14517 }
14518 else
14519 {
14520 /* This special case arises when we have something like this:
14522 template <class T> struct S {
14523 friend void f<int>(int, double);
14524 };
14526 Here, the DECL_TI_TEMPLATE for the friend declaration
14527 will be an IDENTIFIER_NODE. We are being called from
14528 tsubst_friend_function, and we want only to create a
14529 new decl (R) with appropriate types so that we can call
14530 determine_specialization. */
14531 friend_case:
14534 }
14541 /* If this is a static or xobj lambda, remove the 'this' pointer added in
14542 tsubst_lambda_expr now that we know the closure type. */
14556 /* If we hit excessive deduction depth, the type is bogus even if
14557 it isn't error_mark_node, so don't build a decl. */
14561 /* We do NOT check for matching decls pushed separately at this
14562 point, as they may not represent instantiations of this
14563 template, and in any case are considered separate under the
14564 discrete model. */
14568 /* Clear out the mangled name and RTL for the instantiation. */
14571 /* Leave DECL_INITIAL set on deleted instantiations. */
14577 /* Handle explicit(dependent-expr). */
14579 {
14587 else
14588 {
14591 }
14592 }
14594 /* OpenMP UDRs have the only argument a reference to the declared
14595 type. We want to diagnose if the declared type is a reference,
14596 which is invalid, but as references to references are usually
14597 quietly merged, diagnose it here. */
14599 {
14600 tree argtype
14605 "reference type %qT in "
14609 argtype);
14610 }
14613 /* Type-conversion operator. Reconstruct the name, in
14614 case it's the name of one of the template's parameters. */
14624 {
14629 }
14638 /* If this is an instantiation of a function with internal
14639 linkage, we already know what object file linkage will be
14640 assigned to the instantiation. */
14649 /* We'll re-clone as appropriate in instantiate_template. */
14652 /* If we aren't complaining now, return on error before we register
14653 the specialization so that we'll complain eventually. */
14659 /* If we are looking at an xobj lambda, we might need to check the type of
14660 its xobj parameter. */
14662 {
14669 /* If a lambda has an empty capture clause, an xobj parameter of
14672 /* If we are coming from tsubst_lambda_expr we might not have
14673 substituted into our xobj parameter yet. We can't error out until
14674 we know what the type really is so do nothing...
14675 ...but if we are instantiating the call op for real and we don't
14676 have a real type then something has gone incredibly wrong. */
14678 else
14679 {
14680 /* We have a lambda with captures, and know the type of the xobj
14681 parameter, time to check it. */
14684 {
14685 /* This error does not emit when the lambda's call operator
14686 template is instantiated by taking its address, such as in
14687 the following case:
14689 auto f = [x = 0](this auto&&){};
14690 int (*fp)(int&) = &decltype(f)::operator();
14692 It only emits when explicitly calling the call operator with
14693 an explicit template parameter:
14695 template<typename T>
14696 struct S : T {
14697 using T::operator();
14698 operator int() const {return {};}
14699 };
14701 auto s = S{[x = 0](this auto&&) {}};
14702 s.operator()<int>();
14704 This is due to resolve_address_of_overloaded_function being
14705 deficient at reporting candidates when overload resolution
14706 fails.
14708 This diagnostic will be active in the first case if/when
14709 resolve_address_of_overloaded_function is fixed to properly
14710 emit candidates upon failure to resolve to an overload. */
14715 }
14716 }
14717 }
14719 /* Associate the constraints directly with the instantiation. We
14720 don't substitute through the constraints; that's only done when
14721 they are checked. */
14734 /* Set up the DECL_TEMPLATE_INFO for R. There's no need to do
14735 this in the special friend case mentioned above where
14736 GEN_TMPL is NULL. */
14738 {
14744 {
14745 tree new_r
14748 /* We instantiated this while substituting into
14749 the type earlier (template/friend54.C). */
14751 }
14753 /* We're not supposed to instantiate default arguments
14754 until they are called, for a template. But, for a
14755 declaration like:
14757 template <class T> void f ()
14758 { extern void g(int i = T()); }
14760 we should do the substitution when the template is
14761 instantiated. We handle the member function case in
14762 instantiate_class_template since the default arguments
14763 might refer to other members of the class. */
14768 }
14770 {
14773 }
14774 else
14777 /* Copy the list of befriending classes. */
14781 {
14785 }
14788 {
14792 /* If this is an instantiation of a member template, clone it.
14793 If it isn't, that'll be handled by
14794 clone_constructors_and_destructors. */
14797 }
14803 /* Possibly limit visibility based on template args. */
14806 {
14810 }
14825 }
14827 /* Subroutine of tsubst_decl for the case when T is a TEMPLATE_DECL. */
14829 static tree
14832 {
14833 /* We can get here when processing a member function template,
14834 member class template, or template template parameter. */
14837 tree spec;
14838 tree tmpl_args;
14840 tree r;
14844 {
14845 /* Template template parameter is treated here. */
14849 /* If we get a real template back, return it. This can happen in
14850 the context of most_specialized_partial_spec. */
14853 else
14854 /* The new TEMPLATE_DECL was built in
14855 reduce_template_parm_level. */
14858 }
14861 {
14862 /* We might already have an instance of this template.
14863 The ARGS are for the surrounding class type, so the
14864 full args contain the tsubst'd args for the context,
14865 plus the innermost args from the template decl. */
14869 /* Because this is a template, the arguments will still be
14870 dependent, even after substitution. If
14871 PROCESSING_TEMPLATE_DECL is not set, the dependency
14872 predicates will short-circuit. */
14880 /* If this is a default template template argument,
14881 tsubst might not have changed anything. */
14888 {
14890 /* Type partial instantiations are stored as the type by
14891 lookup_template_class_1, not here as the template. */
14896 }
14897 }
14899 /* Make a new template decl. It will be similar to the
14900 original, but will record the current template arguments.
14901 We also create a new function declaration, which is just
14902 like the old one, but points to this new template, rather
14903 than the old one. */
14908 // Build new template info linking to the original template decl.
14910 {
14913 }
14914 else
14917 /* The template parameters for this new template are all the
14918 template parameters for the old template, except the
14919 outermost level of parameters. */
14922 = current_template_parms
14923 = (lambda_tparms
14924 ? lambda_tparms
14926 complain));
14934 else
14935 {
14937 {
14940 }
14944 else
14946 }
14952 {
14953 /* For a partial specialization, we need to keep pointing to
14954 the primary template. */
14956 {
14959 }
14963 }
14965 {
14968 }
14969 else
14970 {
14972 /* Set DECL_TI_ARGS to the full set of template arguments,
14973 which tsubst_function_decl / tsubst_decl didn't do due to
14974 use_spec_table=false. */
14977 }
14984 {
14985 /* Propagate module information from the decl. */
14988 /* If this is a constrained template, the above tsubst of
14989 inner can find the unconstrained template, which may have
14990 come from an import. This is ok, because we don't
14991 register this instantiation (see below). */
14993 || (TEMPLATE_PARMS_CONSTRAINTS
14995 }
15006 {
15007 /* Record this non-type partial instantiation. */
15008 /* FIXME we'd like to always register the TEMPLATE_DECL, or always
15009 the DECL_TEMPLATE_RESULT, but it seems the modules code relies
15010 on this current behavior. */
15013 else
15015 }
15018 }
15020 /* True if FN is the op() for a lambda in an uninstantiated template. */
15022 bool
15024 {
15029 }
15031 /* True if FN is the substitution (via tsubst_lambda_expr) of a function for
15032 which the above is true. */
15034 bool
15036 {
15042 }
15044 /* Return the LAMBDA_EXPR from which T was ultimately regenerated.
15045 If T is not a regenerated LAMBDA_EXPR, return T. */
15047 tree
15049 {
15053 }
15055 /* Return the set of template arguments used to regenerate the lambda T
15056 from its most general lambda. */
15058 tree
15060 {
15066 else
15068 }
15070 /* We're instantiating a variable from template function TCTX. Return the
15071 corresponding current enclosing scope. We can match them up using
15072 DECL_SOURCE_LOCATION because lambdas only ever have one source location, and
15073 the DECL_SOURCE_LOCATION for a function instantiation is updated to match
15074 the template definition in regenerate_decl_from_template. */
15076 static tree
15078 {
15081 /* We shouldn't ever need to do this for other artificial functions. */
15088 }
15090 /* Substitute the ARGS into the T, which is a _DECL. Return the
15091 result of the substitution. Issue error and warning messages under
15092 control of COMPLAIN. The flag USE_SPEC_TABLE controls if we look up
15093 and insert into the specializations table or if we can assume it's
15094 the caller's responsibility; this is used by instantiate_template
15095 to avoid doing some redundant work. */
15097 static tree
15100 {
15101 #define RETURN(EXP) do { r = (EXP); goto out; } while(0)
15102 location_t saved_loc;
15110 /* Set the filename and linenumber to improve error-reporting. */
15115 {
15124 use_spec_table);
15128 {
15136 {
15137 /* If there is a local specialization that isn't a
15138 parameter pack, it means that we're doing a "simple"
15139 substitution from inside tsubst_pack_expansion. Just
15140 return the local specialization (which will be a single
15141 parm). */
15148 /* Expand the TYPE_PACK_EXPANSION that provides the types for
15149 the parameters in this function parameter pack. */
15153 {
15156 /* Zero-length parameter packs are boring. Just substitute
15157 into the chain. */
15161 }
15162 else
15163 {
15164 /* All we did was update the type. Make a note of that. */
15167 }
15168 }
15170 /* Loop through all of the parameters we'll build. When T is
15171 a function parameter pack, LEN is the number of expanded
15172 types in EXPANDED_TYPES; otherwise, LEN is 1. */
15175 {
15182 /* We're on the Ith parameter of the function parameter
15183 pack. */
15184 {
15185 /* Get the Ith type. */
15188 /* Rename the parameter to include the index. */
15191 }
15193 /* We're dealing with a normal parameter. */
15201 {
15204 else
15207 }
15218 /* Keep track of the first new parameter we
15219 generate. That's what will be returned to the
15220 caller. */
15224 /* Build a proper chain of parameters when substituting
15225 into a function parameter pack. */
15228 }
15230 /* If cp_unevaluated_operand is set, we're just looking for a
15231 single dummy parameter, so don't keep going. */
15236 /* FIRST_R contains the start of the chain we've built. */
15238 }
15242 {
15249 {
15250 /* This field is a lambda capture pack. Return a TREE_VEC of
15251 the expanded fields to instantiate_class_template_1. */
15255 {
15258 }
15259 else
15260 {
15261 /* All we did was update the type. Make a note of that. */
15264 }
15265 }
15268 {
15271 {
15275 }
15285 /* For bit-fields, DECL_BIT_FIELD_REPRESENTATIVE gives the
15286 number of bits. */
15291 {
15292 /* Set up DECL_TEMPLATE_INFO so that we can get at the
15293 NSDMI in perform_member_init. Still set DECL_INITIAL
15294 so that we know there is one. */
15299 }
15300 /* We don't have to set DECL_CONTEXT here; it is set by
15301 finish_member_declaration. */
15310 }
15314 }
15318 /* We reach here only for member using decls. We also need to check
15319 uses_template_parms because DECL_DEPENDENT_P is not set for a
15320 using-declaration that designates a member of the current
15321 instantiation (c++/53549). */
15324 {
15325 /* True iff this using-decl was written as a pack expansion
15326 (and a pack appeared in its scope or name). If a pack
15327 appeared in both, we expand the packs separately and
15328 manually merge them. */
15333 {
15336 in_decl);
15338 }
15339 else
15345 {
15349 {
15352 }
15356 }
15357 else
15365 {
15367 {
15372 }
15374 }
15382 {
15391 {
15394 }
15398 }
15402 }
15403 else
15404 {
15407 }
15412 {
15423 {
15424 /* If this is the canonical decl, we don't have to
15425 mess with instantiations, and often we can't (for
15426 typename, template type parms and such). Note that
15427 TYPE_NAME is not correct for the above test if
15428 we've copied the type for a typedef. */
15434 }
15436 /* Check to see if we already have the specialization we
15437 need. */
15443 {
15446 {
15448 complain,
15451 /* The context and type of an injected-class-name are
15452 the same, so we don't need to substitute both. */
15454 /* If CTX is unchanged, then T is in fact the
15455 specialization we want. That situation occurs when
15456 referencing a static data member within in its own
15457 class. We can use pointer equality, rather than
15458 same_type_p, because DECL_CONTEXT is always
15459 canonical... */
15461 /* ... unless T is a member template; in which
15462 case our caller can be willing to create a
15463 specialization of that template represented
15464 by T. */
15468 }
15471 {
15474 {
15481 }
15482 else
15484 }
15485 }
15486 else
15487 {
15489 /* Subsequent calls to pushdecl will fill this in. */
15491 /* A local variable. */
15493 /* Unless this is a reference to a static variable from an
15494 enclosing function, in which case we need to fill it in now. */
15496 {
15500 }
15502 }
15503 /* If we already have the specialization we need, there is
15504 nothing more to do. */
15506 {
15509 }
15511 /* Create a new node for the specialization we need. */
15513 {
15516 else
15526 /* Substituting the type might have recursively instantiated this
15527 same alias (c++/86171). */
15530 {
15533 }
15534 }
15539 {
15543 {
15544 /* It may seem that this case cannot occur, since:
15546 typedef void f();
15547 void g() { f x; }
15549 declares a function, not a variable. However:
15551 typedef void f();
15552 template <typename T> void g() { T t; }
15553 template void g<f>();
15555 is an attempt to declare a variable with function
15556 type. */
15558 /* R is not yet sufficiently initialized, so we
15559 just use its name. */
15562 }
15564 /* Wait until cp_finish_decl to set this again, to handle
15565 circular dependency (template/instantiate6.C). */
15570 {
15572 /* If the DECL_VALUE_EXPR is converted to the declared type,
15573 preserve the identity so that gimplify_type_sizes works. */
15579 {
15582 }
15591 else
15595 }
15599 }
15605 /* Clear out the mangled name and RTL for the instantiation. */
15611 /* The initializer must not be expanded until it is required;
15612 see [temp.inst]. */
15616 {
15622 /* Possibly limit visibility based on template args. */
15625 {
15629 }
15633 }
15636 {
15637 /* A static data member declaration is always marked
15638 external when it is declared in-class, even if an
15639 initializer is present. We mimic the non-template
15640 processing here. */
15649 }
15650 else
15651 {
15656 }
15665 /* Preserve a typedef that names a type. */
15667 {
15671 /* common_handle_aligned_attribute doesn't apply the alignment
15672 to DECL_ORIGINAL_TYPE. */
15676 }
15679 }
15684 }
15685 #undef RETURN
15687 out:
15688 /* Restore the file and line information. */
15692 }
15694 /* Substitute into the complete parameter type list PARMS. */
15696 tree
15698 tree args,
15699 tsubst_flags_t complain,
15700 tree in_decl)
15701 {
15703 }
15705 /* Substitute into the ARG_TYPES of a function type.
15706 If END is a TREE_CHAIN, leave it and any following types
15707 un-substituted. */
15709 static tree
15711 tree args,
15712 tree end,
15713 tsubst_flags_t complain,
15714 tree in_decl)
15715 {
15724 {
15725 /* For a pack expansion, perform substitution on the
15726 entire expression. Later on, we'll handle the arguments
15727 one-by-one. */
15732 /* So that we'll spin through the parameters, one by one. */
15734 else
15735 {
15736 /* We only partially substituted into the parameter
15737 pack. Our type is TYPE_PACK_EXPANSION. */
15740 }
15741 }
15742 else
15745 /* Check if a substituted type is erroneous before substituting into
15746 the rest of the chain. */
15748 {
15755 {
15757 {
15761 }
15763 }
15764 }
15766 /* We do not substitute into default arguments here. The standard
15767 mandates that they be instantiated only when needed, which is
15768 done in build_over_call. */
15771 /* Except that we do substitute default arguments under tsubst_lambda_expr,
15772 since the new op() won't have any associated template arguments for us
15773 to refer to later. */
15785 {
15789 /* Do array-to-pointer, function-to-pointer conversion, and ignore
15790 top-level qualifiers as required. */
15794 {
15795 /* We've instantiated a template before its default arguments
15796 have been parsed. This can happen for a nested template
15797 class, and is not an error unless we require the default
15798 argument in a call of this function. */
15799 remaining_arg_types
15802 remaining_arg_types);
15803 }
15804 else
15805 remaining_arg_types
15807 }
15810 }
15812 /* Substitute into a FUNCTION_TYPE or METHOD_TYPE. This routine does
15813 *not* handle the exception-specification for FNTYPE, because the
15814 initial substitution of explicitly provided template parameters
15815 during argument deduction forbids substitution into the
15816 exception-specification:
15818 [temp.deduct]
15820 All references in the function type of the function template to the
15821 corresponding template parameters are replaced by the specified tem-
15822 plate argument values. If a substitution in a template parameter or
15823 in the function type of the function template results in an invalid
15824 type, type deduction fails. [Note: The equivalent substitution in
15825 exception specifications is done only when the function is instanti-
15826 ated, at which point a program is ill-formed if the substitution
15827 results in an invalid type.] */
15829 static tree
15831 tree args,
15832 tsubst_flags_t complain,
15833 tree in_decl)
15834 {
15835 tree return_type;
15838 /* The TYPE_CONTEXT is not used for function/method types. */
15841 /* DR 1227: Mixing immediate and non-immediate contexts in deduction
15842 failure. */
15846 {
15847 /* Substitute the argument types. */
15859 {
15860 /* DR 1207: 'this' is in scope in the trailing return type. */
15862 }
15864 /* Substitute the return type. */
15868 {
15871 }
15872 }
15873 else
15874 /* Substitute the return type. */
15879 /* DR 486 clarifies that creation of a function type with an
15880 invalid return type is a deduction failure. */
15883 {
15885 {
15888 else
15890 }
15892 }
15895 {
15896 /* Substitute the argument types. */
15901 }
15903 /* Construct a new type node and return it. */
15906 }
15908 /* FNTYPE is a FUNCTION_TYPE or METHOD_TYPE. Substitute the template
15909 ARGS into that specification, and return the substituted
15910 specification. If there is no specification, return NULL_TREE. */
15912 static tree
15914 tree args,
15915 tsubst_flags_t complain,
15916 tree in_decl,
15918 {
15919 tree specs;
15920 tree new_specs;
15925 {
15926 /* A noexcept-specifier. */
15931 {
15932 /* Defer instantiation of noexcept-specifiers to avoid
15933 excessive instantiations (c++/49107). */
15936 {
15937 /* We already partially instantiated this member template,
15938 so combine the new args with the old. */
15943 }
15944 else
15945 {
15948 }
15949 }
15950 else
15951 {
15953 {
15955 args);
15957 }
15959 }
15961 /* We've instantiated a template before a noexcept-specifier
15962 contained therein has been parsed. This can happen for
15963 a nested template class:
15965 struct S {
15966 template<typename> struct B { B() noexcept(...); };
15967 struct A : B<int> { ... use B() ... };
15968 };
15970 where completing B<int> will trigger instantiating the
15971 noexcept, even though we only parse it at the end of S. */
15973 {
15976 }
15977 }
15979 {
15982 else
15984 {
15985 tree spec;
15990 {
15991 /* Expand the pack expansion type. */
15994 in_decl);
16000 else
16001 {
16002 /* We're substituting into a member template, so
16003 we got a TYPE_PACK_EXPANSION back. Add that
16004 expansion and move on. */
16008 expanded_specs,
16009 complain);
16012 }
16013 }
16016 {
16019 else
16024 complain);
16025 }
16028 }
16029 }
16031 }
16033 /* Substitute through a TREE_LIST of types or expressions, handling pack
16034 expansions. */
16036 tree
16038 {
16045 ;
16047 {
16051 }
16054 else
16062 ;
16064 {
16068 }
16071 else
16078 ;
16083 else
16094 /* Determine the number of arguments. */
16096 {
16099 }
16102 else
16106 {
16114 else
16116 }
16119 }
16121 /* Take the tree structure T and replace template parameters used
16122 therein with the argument vector ARGS. IN_DECL is an associated
16123 decl for diagnostics. If an error occurs, returns ERROR_MARK_NODE.
16124 Issue error and warning messages under control of COMPLAIN. Note
16125 that we must be relatively non-tolerant of extensions here, in
16126 order to preserve conformance; if we allow substitutions that
16127 should not be allowed, we may allow argument deductions that should
16128 not succeed, and therefore report ambiguous overload situations
16129 where there are none. In theory, we could allow the substitution,
16130 but indicate that it should have failed, and allow our caller to
16131 make sure that the right thing happens, but we don't try to do this
16132 yet.
16134 This function is used for dealing with types, decls and the like;
16135 for expressions, use tsubst_expr or tsubst_copy. */
16137 tree
16139 {
16174 /* Reuse typedefs. We need to do this to handle dependent attributes,
16175 such as attribute aligned. */
16178 {
16182 {
16183 /* DECL represents an alias template and we want to
16184 instantiate it. */
16188 }
16192 {
16196 }
16201 else
16202 /* The typedef is from a non-template context. */
16206 {
16208 r = cp_build_qualified_type
16212 }
16213 else
16214 {
16215 /* We don't have an instantiation yet, so drop the typedef. */
16220 }
16221 }
16238 {
16242 /* Fall through. */
16268 {
16273 /* Fix up type of the magic NOP_EXPR with TREE_SIDE_EFFECTS if
16274 needed. */
16280 /* If we're in a partial instantiation, preserve the magic NOP_EXPR
16281 with TREE_SIDE_EFFECTS that indicates this is not an integral
16282 constant expression. */
16285 {
16288 }
16291 }
16295 {
16303 else
16305 }
16306 /* Fall through. */
16310 {
16324 {
16327 /* See through ARGUMENT_PACK_SELECT arguments. */
16330 }
16335 {
16337 /* If ARG is an argument pack, we don't actually want to
16338 perform a substitution here, because substitutions
16339 for argument packs are only done
16340 element-by-element. We can get to this point when
16341 substituting the type of a non-type template
16342 parameter pack, when that type actually contains
16343 template parameter packs from an outer template, e.g.,
16345 template<typename... Types> struct A {
16346 template<Types... Values> struct B { };
16347 }; */
16351 {
16354 /* When building concept checks for the purpose of
16355 deducing placeholders, we can end up with wildcards
16356 where types are expected. Adjust this to the deduced
16357 value. */
16365 return cp_build_qualified_type
16367 }
16369 {
16370 /* We are processing a type constructed from a
16371 template template parameter. */
16382 /* Consider this code:
16384 template <template <class> class Template>
16385 struct Internal {
16386 template <class Arg> using Bind = Template<Arg>;
16387 };
16389 template <template <class> class Template, class Arg>
16390 using Instantiate = Template<Arg>; //#0
16392 template <template <class> class Template,
16393 class Argument>
16394 using Bind =
16395 Instantiate<Internal<Template>::template Bind,
16396 Argument>; //#1
16398 When #1 is parsed, the
16399 BOUND_TEMPLATE_TEMPLATE_PARM representing the
16400 parameter `Template' in #0 matches the
16401 UNBOUND_CLASS_TEMPLATE representing the argument
16402 `Internal<Template>::template Bind'; We then want
16403 to assemble the type `Bind<Argument>' that can't
16404 be fully created right now, because
16405 `Internal<Template>' not being complete, the Bind
16406 template cannot be looked up in that context. So
16407 we need to "store" `Bind<Argument>' for later
16408 when the context of Bind becomes complete. Let's
16409 store that in a TYPENAME_TYPE. */
16413 argvec),
16414 typename_type,
16415 complain);
16417 /* We can get a TEMPLATE_TEMPLATE_PARM here when we
16418 are resolving nested-types in the signature of a
16419 member function templates. Otherwise ARG is a
16420 TEMPLATE_DECL and is the real template to be
16421 instantiated. */
16429 complain);
16430 return cp_build_qualified_type
16432 }
16435 else
16436 /* TEMPLATE_PARM_INDEX. */
16438 }
16441 /* This can happen during the attempted tsubst'ing in
16442 unify. This means that we don't yet have any information
16443 about the template parameter in question. */
16446 /* Early in template argument deduction substitution, we don't
16447 want to reduce the level of 'auto', or it will be confused
16448 with a normal template parm in subsequent deduction.
16449 Similarly, don't reduce the level of template parameters to
16450 avoid mismatches when deducing their types. */
16454 /* If we get here, we must have been looking at a parm for a
16455 more deeply nested template. Make a new version of this
16456 template parameter, but with a lower level. */
16459 {
16464 {
16467 }
16473 /* Cache lowering a type parameter or a simple template
16474 template parameter. */
16478 {
16490 /* Propagate constraints on placeholders since they are
16491 only instantiated during satisfaction. */
16496 else
16498 }
16506 {
16508 /* We might need to substitute into the types of non-type
16509 template parameters. This also lowers the level of
16510 the ttp appropriately. */
16523 }
16526 /* OK, now substitute the type of the non-type parameter. We
16527 couldn't do it earlier because it might be an auto parameter,
16528 and we wouldn't need to if we had an argument. */
16537 }
16540 }
16546 /* We should never be tsubsting a binfo. */
16550 /* A vector of template arguments. */
16556 {
16560 /* [temp.deduct]
16562 Type deduction may fail for any of the following
16563 reasons:
16565 -- Attempting to create a pointer to reference type.
16566 -- Attempting to create a reference to a reference type or
16567 a reference to void.
16569 Core issue 106 says that creating a reference to a reference
16570 during instantiation is no longer a cause for failure. We
16571 only enforce this check in strict C++98 mode. */
16575 {
16578 /* We keep track of the last time we issued this error
16579 message to avoid spewing a ton of messages during a
16580 single bad template instantiation. */
16583 {
16588 else
16591 }
16594 }
16598 {
16600 {
16603 type);
16604 else
16606 type);
16607 }
16609 }
16611 {
16615 }
16617 /* In C++0x, during template argument substitution, when there is an
16618 attempt to create a reference to a reference type, reference
16619 collapsing is applied as described in [14.3.1/4 temp.arg.type]:
16621 "If a template-argument for a template-parameter T names a type
16622 that is a reference to a type A, an attempt to create the type
16623 'lvalue reference to cv T' creates the type 'lvalue reference to
16624 A,' while an attempt to create the type type rvalue reference to
16625 cv T' creates the type T"
16626 */
16627 r = cp_build_reference_type
16630 else
16635 /* Will this ever be needed for TYPE_..._TO values? */
16639 }
16641 {
16644 {
16645 /* [temp.deduct]
16647 Type deduction may fail for any of the following
16648 reasons:
16650 -- Attempting to create "pointer to member of T" when T
16651 is not a class type. */
16655 }
16657 {
16661 }
16663 {
16667 }
16670 {
16671 /* The type of the implicit object parameter gets its
16672 cv-qualifiers from the FUNCTION_TYPE. */
16673 tree memptr;
16674 tree method_type
16679 complain);
16680 }
16681 else
16684 complain);
16685 }
16688 {
16689 tree fntype;
16690 tree specs;
16695 /* Substitute the exception specification. */
16703 }
16705 {
16710 /* As an optimization, we avoid regenerating the array type if
16711 it will obviously be the same as T. */
16715 /* These checks should match the ones in create_array_type_for_decl.
16717 [temp.deduct]
16719 The deduction may fail for any of the following reasons:
16721 -- Attempting to create an array with an element type that
16722 is void, a function type, or a reference type, or [DR337]
16723 an abstract class type. */
16729 {
16733 }
16746 {
16749 }
16752 }
16755 {
16758 {
16761 in_decl);
16766 {
16771 }
16773 }
16774 else
16787 {
16791 }
16793 {
16794 /* Normally, make_typename_type does not require that the CTX
16795 have complete type in order to allow things like:
16797 template <class T> struct S { typename S<T>::X Y; };
16799 But, such constructs have already been resolved by this
16800 point, so here CTX really should have complete type, unless
16801 it's a partial instantiation. */
16804 }
16806 /* FIXME: TYPENAME_IS_CLASS_P conflates 'class' vs 'struct' vs 'union'
16807 tags. TYPENAME_TYPE should probably remember the exact tag that
16808 was written. */
16809 enum tag_types tag_type
16819 {
16822 }
16825 {
16827 {
16831 else
16833 }
16835 {
16839 else
16841 }
16842 }
16844 return cp_build_qualified_type
16846 }
16849 {
16861 }
16864 {
16865 tree type;
16879 complain);
16880 }
16883 {
16884 tree type;
16901 else
16902 {
16906 /* In a template ~id could be either a complement expression
16907 or an unqualified-id naming a destructor; if instantiating
16908 it produces an expression, it's not an id-expression or
16909 member access. */
16912 }
16917 }
16920 {
16924 else
16931 }
16951 /* We should use one of the expression tsubsts for these codes. */
16957 }
16958 }
16960 /* Convenience wrapper over tsubst for substituting into the LHS
16961 of the :: scope resolution operator. */
16963 static tree
16965 {
16968 }
16970 /* Convenience wrapper over tsubst for substituting into an id-expression
16971 without resolving its terminal name. */
16973 static tree
16975 {
16977 }
16979 /* OLDFNS is a lookup set of member functions from some class template, and
16980 NEWFNS is a lookup set of member functions from NEWTYPE, a specialization
16981 of that class template. Return the subset of NEWFNS which are
16982 specializations of a function from OLDFNS. */
16984 static tree
16986 {
16987 /* Record all member functions from the old lookup set OLDFNS into
16988 VISIBLE_SET. */
16992 {
16994 {
16995 /* Imprecisely handle dependent using-decl by keeping all members
16996 in the new lookup set that are defined in a base class, i.e.
16997 members that could plausibly have been introduced by this
16998 dependent using-decl.
16999 FIXME: Track which members are introduced by a dependent
17000 using-decl precisely, perhaps by performing another lookup
17001 from the substituted USING_DECL_SCOPE. */
17004 }
17005 else
17007 }
17009 /* Returns true iff (a less specialized version of) FN appeared in
17010 the old lookup set OLDFNS. */
17013 /* FN is a member function from a base class, introduced via a
17014 using-decl; if it might have been introduced by a dependent
17015 using-decl then just conservatively keep it, otherwise look
17016 in the old lookup set for FN exactly. */
17019 /* FN is a member function template from the current class;
17020 look in the old lookup set for the TEMPLATE_DECL from which
17021 it was specialized. */
17023 else
17024 /* FN is a non-template member function from the current class;
17025 look in the old lookup set for the FUNCTION_DECL from which
17026 it was specialized. */
17029 };
17034 {
17037 }
17041 /* Filter out from NEWFNS the member functions that weren't
17042 previously visible according to OLDFNS. */
17047 {
17049 filtered_size++;
17050 }
17056 }
17058 /* tsubst a BASELINK. OBJECT_TYPE, if non-NULL, is the type of the
17059 expression on the left-hand side of the "." or "->" operator. We
17060 only do the lookup if we had a dependent BASELINK. Otherwise we
17061 adjust it onto the instantiated heirarchy. */
17063 static tree
17066 {
17078 {
17085 }
17093 {
17098 /* See maybe_dependent_member_ref. */
17100 {
17103 template_args);
17106 }
17109 /* Treat as-if non-dependent below. */
17114 complain);
17116 {
17117 /* Filter out from the new lookup set those functions which didn't
17118 appear in the original lookup set (in a less specialized form).
17119 This is needed to preserve the consistency of member lookup
17120 performed in an incomplete-class context, within which
17121 later-declared members ought to remain invisible. */
17124 binfo_type);
17126 }
17129 {
17135 }
17138 }
17139 else
17140 {
17141 /* We're going to overwrite pieces below, make a duplicate. */
17145 {
17146 /* The decl we found was from non-dependent scope, but we still need
17147 to update the binfos for the instantiated qualifying_scope. */
17151 }
17152 }
17154 /* If lookup found a single function, mark it as used at this point.
17155 (If lookup found multiple functions the one selected later by
17156 overload resolution will be marked as used at that point.) */
17158 {
17164 /* We might have instantiated an auto function. */
17166 }
17169 {
17170 /* Add back the template arguments, if present. */
17175 /* Update the conversion operator type. */
17177 }
17183 {
17185 qualifying_scope,
17186 object_type);
17188 /* We need to call adjust_result_of_qualified_name_lookup in case the
17189 destructor names a base class, but we unset BASELINK_QUALIFIED_P
17190 so that we still get virtual function binding. */
17192 }
17195 }
17197 /* Like tsubst_expr for a SCOPE_REF, given by QUALIFIED_ID. DONE is
17198 true if the qualified-id will be a postfix-expression in-and-of
17199 itself; false if more of the postfix-expression follows the
17200 QUALIFIED_ID. ADDRESS_P is true if the qualified-id is the operand
17201 of "&". */
17203 static tree
17207 {
17208 tree expr;
17209 tree scope;
17210 tree name;
17212 tree template_args;
17217 /* Figure out what name to look up. */
17220 {
17229 }
17230 else
17231 {
17234 }
17236 /* Substitute into the qualifying scope. When there are no ARGS, we
17237 are just trying to simplify a non-dependent expression. In that
17238 case the qualifying scope may be dependent, and, in any case,
17239 substituting will not help. */
17242 {
17245 }
17246 else
17250 {
17252 /* We built one in tsubst_baselink. */
17254 else
17255 {
17258 template_args);
17260 QUALIFIED_NAME_IS_TEMPLATE
17262 }
17265 }
17268 {
17270 {
17271 /* A BIT_NOT_EXPR is used to represent a destructor. */
17273 {
17277 }
17278 else
17281 }
17282 else
17286 {
17288 {
17292 }
17294 }
17295 }
17298 {
17302 /* Remember that there was a reference to this entity. */
17305 }
17308 {
17314 }
17317 {
17318 /* We may be repeating a check already done during parsing, but
17319 if it was well-formed and passed then, it will pass again
17320 now, and if it didn't, we wouldn't have got here. The case
17321 we want to catch is when we couldn't tell then, and can now,
17322 namely when templ prior to substitution was an
17323 identifier. */
17329 complain);
17330 else
17332 }
17338 {
17339 expr = (adjust_result_of_qualified_name_lookup
17341 expr = (finish_qualified_id_expr
17345 }
17347 /* Expressions do not generally have reference type. */
17349 /* However, if we're about to form a pointer-to-member, we just
17350 want the referenced member referenced. */
17360 }
17362 /* tsubst the initializer for a VAR_DECL. INIT is the unsubstituted
17363 initializer, DECL is the substituted VAR_DECL. Other arguments are as
17364 for tsubst. */
17366 static tree
17369 {
17378 {
17380 {
17382 {
17387 }
17388 }
17390 {
17391 /* If we had an initializer but it
17392 instantiated to nothing,
17393 value-initialize the object. This will
17394 only occur when the initializer was a
17395 pack expansion where the parameter packs
17396 used in that expansion were of length
17397 zero. */
17403 }
17404 }
17407 }
17409 /* If T is a reference to a dependent member of the current instantiation C and
17410 we are trying to refer to that member in a partial instantiation of C,
17411 return a SCOPE_REF; otherwise, return NULL_TREE.
17413 This can happen when forming a C++17 deduction guide, as in PR96199. */
17415 static tree
17417 tree in_decl)
17418 {
17435 {
17444 complain);
17445 }
17450 {
17456 }
17459 {
17462 /* The TYPE_DECL for a typename has DECL_CONTEXT of the typename
17463 scope, but it doesn't need to be rewritten again. */
17467 }
17471 else
17474 }
17476 /* Helper function for tsubst_omp_clauses, used for instantiation of
17477 OMP_CLAUSE_DECL of clauses. */
17479 static tree
17482 {
17486 /* Handle OpenMP iterators. */
17490 {
17491 tree ret;
17494 else
17495 {
17499 {
17513 }
17517 }
17521 }
17523 /* Handle an OpenMP array section represented as a TREE_LIST (or
17524 OMP_CLAUSE_DOACROSS_KIND). An OMP_CLAUSE_DOACROSS (with a depend
17525 kind of OMP_CLAUSE_DOACROSS_SINK) can also be represented as a
17526 TREE_LIST. We can handle it exactly the same as an array section
17527 (purpose, value, and a chain), even though the nomenclature
17528 (low_bound, length, etc) is different. */
17530 {
17531 tree low_bound
17544 }
17546 {
17547 tree low_bound
17550 in_decl);
17558 length);
17559 }
17561 /* Undo convert_from_reference tsubst_expr could have called. */
17567 }
17569 /* Like tsubst_copy, but specifically for OpenMP clauses. */
17571 static tree
17574 {
17580 {
17586 {
17589 {
17595 }
17596 /* FALLTHRU */
17626 /* FALLTHRU */
17660 {
17663 {
17670 }
17671 else
17673 }
17700 {
17703 }
17708 else
17739 }
17742 {
17759 /* tsubst_expr on SCOPE_REF results in returning
17760 finish_non_static_data_member result. Undo that here. */
17764 {
17769 {
17773 CASE_CONVERT:
17782 /* FALLTHRU */
17786 }
17787 }
17793 {
17796 {
17799 }
17800 }
17804 }
17805 }
17809 {
17814 {
17817 }
17818 }
17820 }
17822 /* Like tsubst_expr, but unshare TREE_LIST nodes. */
17824 static tree
17826 tree in_decl)
17827 {
17828 #define RECUR(t) tsubst_copy_asm_operands (t, args, complain, in_decl)
17846 {
17849 else
17850 {
17854 }
17855 }
17860 #undef RECUR
17861 }
17863 /* Used to temporarily communicate the list of #pragma omp parallel
17864 clauses to #pragma omp for instantiation if they are combined
17865 together. */
17870 cp_decomp *);
17872 /* Substitute one OMP_FOR iterator. */
17874 static bool
17878 {
17879 #define RECUR(NODE) \
17880 tsubst_stmt ((NODE), args, complain, in_decl)
17892 {
17895 {
17900 {
17909 else
17911 {
17913 {
17919 }
17922 }
17923 }
17924 }
17928 }
17930 {
17931 /* We need to jump through some hoops to handle declarations in the
17932 init-statement, since we might need to handle auto deduction,
17933 but we need to keep control of initialization. */
17937 }
17938 else
17939 {
17941 {
17944 {
17948 {
17952 CASE_CONVERT:
17960 {
17963 }
17964 /* FALLTHRU */
17968 }
17969 }
17970 }
17971 else
17973 }
17975 {
17981 }
17982 else
17986 {
17992 NULL_TREE);
17993 else
17995 }
17998 {
18006 {
18011 }
18014 }
18024 {
18026 {
18027 /* Declare the variable, but don't let that initialize it. */
18032 }
18035 {
18039 {
18048 }
18049 else
18053 {
18058 }
18059 else
18063 }
18069 }
18072 {
18073 /* Declare and initialize the variable. */
18076 }
18078 {
18083 {
18085 {
18091 {
18094 /* Move lastprivate (decl) clause to OMP_FOR_CLAUSES. */
18099 }
18102 {
18104 decl);
18106 }
18109 {
18111 decl);
18113 }
18114 else
18116 }
18119 }
18121 {
18124 ? OMP_CLAUSE_LASTPRIVATE
18129 {
18132 }
18133 }
18134 }
18137 {
18141 }
18142 else
18146 {
18157 {
18165 }
18166 else
18172 {
18178 }
18182 {
18190 }
18191 else
18197 }
18206 #undef RECUR
18207 }
18209 /* Helper function of tsubst_expr, find OMP_TEAMS inside
18210 of OMP_TARGET's body. */
18212 static tree
18214 {
18217 {
18226 }
18228 }
18230 /* Helper function for tsubst_expr. For decomposition declaration
18231 artificial base DECL, which is tsubsted PATTERN_DECL, tsubst
18232 also the corresponding decls representing the identifiers
18233 of the decomposition declaration. Return DECL if successful
18234 or error_mark_node otherwise, set *FIRST to the first decl
18235 in the list chained through DECL_CHAIN and *CNT to the number
18236 of such decls. */
18238 static tree
18241 {
18246 decl2
18251 {
18253 {
18256 }
18268 else
18269 {
18273 }
18280 {
18283 }
18284 else
18286 }
18289 }
18291 /* Return the proper local_specialization for init-capture pack DECL. */
18293 static tree
18295 {
18296 /* We handle normal pack captures by forwarding to the specialization of the
18297 captured parameter. We can't do that for pack init-captures; we need them
18298 to have their own local_specialization. We created the individual
18299 VAR_DECLs (if any) under build_capture_proxy, and we need to collect them
18300 when we process the DECL_EXPR for the pack init-capture in the template.
18301 So, how do we find them? We don't know the capture proxy pack when
18302 building the individual resulting proxies, and we don't know the
18303 individual proxies when instantiating the pack. What we have in common is
18304 the FIELD_DECL.
18306 So...when we instantiate the FIELD_DECL, we stick the result in
18307 local_specializations. Then at the DECL_EXPR we look up that result, see
18308 how many elements it has, synthesize the names, and look them up. */
18322 {
18327 }
18329 {
18334 else
18336 }
18338 }
18340 /* T is an operand of a template tree being substituted. Return whether
18341 T is dependent such that we should suppress some warnings that would
18342 make sense if the substituted expression were written directly, like
18343 template <int I> bool f() { return I == 2; }
18344 We don't want to warn when instantiating f that comparing two constants
18345 always has the same value.
18347 This is a more limited concept of dependence than instantiation-dependent;
18348 here we don't care whether substitution could fail. */
18350 static bool
18352 {
18361 }
18363 /* A superset of tsubst_expr that also handles statement trees. */
18365 static tree
18367 {
18368 #define RETURN(EXP) do { r = (EXP); goto out; } while(0)
18369 #define RECUR(NODE) \
18370 tsubst_stmt ((NODE), args, complain, in_decl)
18373 tree r;
18374 location_t loc;
18386 {
18388 {
18392 }
18411 else
18424 {
18429 }
18433 {
18435 tree init;
18441 {
18444 {
18448 {
18453 }
18455 }
18456 else
18457 {
18458 /* This is a non-dependent using-decl, and we'll have
18459 used the names it found during template parsing. We do
18460 not want to do the lookup again, because we might not
18461 find the things we found then. */
18464 /* We still need to push the bindings so that we can look up
18465 this name later. */
18468 }
18469 }
18472 {
18473 /* We're in tsubst_lambda_expr, we've already inserted a new
18474 capture proxy, so look it up and register it. */
18475 tree inst;
18477 {
18481 }
18483 {
18484 inst = (retrieve_local_specialization
18488 }
18489 else
18494 }
18501 /* Don't copy the old closure; we'll create a new one in
18502 tsubst_lambda_expr. */
18504 else
18505 {
18509 {
18510 /* By marking the declaration as instantiated, we avoid
18511 trying to instantiate it. Since instantiate_decl can't
18512 handle local variables, and since we've already done
18513 all that needs to be done, that's the right thing to
18514 do. */
18519 /* Anonymous aggregates are a special case. */
18522 {
18525 {
18529 }
18531 }
18536 {
18544 }
18545 else
18546 {
18561 {
18565 }
18570 const_init = (DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P
18573 /* In a non-template function, VLA type declarations are
18574 handled in grokdeclarator; for templates, handle them
18575 now. */
18579 {
18583 asmspec_tree
18587 }
18590 decomp);
18594 }
18595 }
18596 }
18599 }
18609 {
18613 }
18618 {
18619 /* Construct another range_for, if this is not a final
18620 substitution (for inside a generic lambda of a
18621 template). Otherwise convert to a regular for. */
18623 stmt = (processing_template_decl
18634 {
18638 }
18642 unroll
18644 unroll);
18646 {
18653 }
18654 else
18663 }
18670 {
18674 }
18680 {
18684 }
18696 {
18702 }
18705 {
18706 /* We're partially instantiating a generic lambda, but the condition
18707 of the constexpr if is still dependent. Don't substitute into the
18708 branches now, just remember the template arguments. */
18716 }
18720 {
18725 }
18726 else
18727 {
18735 }
18741 {
18751 }
18759 else
18767 else
18788 {
18794 {
18799 }
18800 }
18804 {
18806 tree label;
18813 }
18819 /* Computed goto's must be tsubst'd into. On the other hand,
18820 non-computed gotos must not be; the identifier in question
18821 will have no binding. */
18823 else
18829 {
18846 }
18851 {
18856 }
18857 else
18858 {
18863 else
18870 else
18876 else
18878 }
18882 {
18886 {
18888 /* Prevent instantiate_decl from trying to instantiate
18889 this variable. We've already done all that needs to be
18890 done. */
18893 }
18898 }
18904 /* This is a partial instantiation, try again when full. */
18907 {
18908 /* Local classes are not independent templates; they are
18909 instantiated along with their containing function. And this
18910 way we don't have to deal with pushing out of one local class
18911 to instantiate a member of another local class. */
18912 /* Closures are handled by the LAMBDA_EXPR. */
18928 }
18932 {
18949 }
18978 {
18985 }
19001 {
19015 in_decl);
19017 {
19024 }
19035 any_range_for
19042 {
19051 }
19052 else
19057 else
19064 else
19065 {
19073 }
19076 t));
19078 }
19084 /* FALLTHRU */
19094 in_decl);
19096 {
19101 }
19102 else
19103 {
19107 }
19112 {
19114 "%<#pragma omp critical%> with %<hint%> clause requires "
19117 }
19128 {
19131 {
19136 }
19137 else
19138 {
19142 }
19144 }
19145 else
19147 OMP_CLAUSE_DEPEND_INVALID,
19156 ? C_ORT_ACC
19175 {
19178 /* For combined target teams, ensure the num_teams and
19179 thread_limit clause expressions are evaluated on the host,
19180 before entering the target construct. */
19189 {
19192 tf_none);
19199 OMP_CLAUSE_FIRSTPRIVATE);
19203 }
19204 }
19241 {
19245 }
19246 else
19258 /* FALLTHRU */
19276 {
19282 {
19285 }
19287 {
19291 {
19294 }
19299 }
19300 else
19301 {
19304 }
19309 }
19310 else
19311 {
19318 {
19321 }
19324 {
19329 {
19332 }
19334 {
19338 {
19341 }
19346 }
19347 else
19348 {
19351 }
19355 }
19356 else
19357 {
19361 }
19365 }
19369 {
19375 {
19379 {
19384 }
19388 }
19389 else
19390 {
19395 }
19396 }
19400 {
19404 }
19417 /* If the first operand was a statement, we're done with it. */
19422 complain));
19431 }
19434 out:
19437 #undef RECUR
19438 #undef RETURN
19439 }
19441 /* Instantiate the special body of the artificial DECL_OMP_DECLARE_REDUCTION
19442 function. For description of the body see comment above
19443 cp_parser_omp_declare_reduction_exprs. */
19445 static void
19447 {
19453 tree_stmt_iterator tsi;
19464 {
19471 /* tsubsting a local var_decl leaves DECL_CONTEXT null, as we
19472 expect to be pushing it. */
19484 }
19486 {
19506 }
19507 }
19509 /* T is a postfix-expression that is not being used in a function
19510 call. Return the substituted version of T. */
19512 static tree
19514 tsubst_flags_t complain,
19515 tree in_decl)
19516 {
19520 else
19524 }
19526 /* Subroutine of tsubst_lambda_expr: add the FIELD/INIT capture pair to the
19527 LAMBDA_EXPR_CAPTURE_LIST passed in LIST. Do deduction for a previously
19528 dependent init-capture. EXPLICIT_P is true if the original list had
19529 explicit captures. */
19531 static void
19533 tsubst_flags_t complain)
19534 {
19536 {
19539 {
19543 }
19550 }
19553 }
19555 /* T is a LAMBDA_EXPR. Generate a new LAMBDA_EXPR for the current
19556 instantiation context. Instantiating a pack expansion containing a lambda
19557 might result in multiple lambdas all based on the same lambda in the
19558 template. */
19560 tree
19562 {
19576 else
19587 {
19592 else
19604 {
19605 /* For a VLA, simply tsubsting the field type won't work, we need to
19606 go through add_capture again. XXX do we want to do this for all
19607 captures? */
19608 tree name = (get_identifier
19617 }
19624 {
19625 /* Remember these for when we've pushed local_specializations. */
19628 }
19634 {
19643 complain);
19644 }
19645 else
19646 {
19652 }
19653 }
19662 /* If we're pushed into another scope (PR105652), fix it. */
19667 /* Do this again now that LAMBDA_EXPR_EXTRA_SCOPE is set. */
19684 {
19687 }
19690 {
19693 }
19697 else
19698 {
19699 /* The body of a lambda-expression is not a subexpression of the
19700 enclosing expression. Parms are to have DECL_CHAIN tsubsted,
19701 which would be skipped if cp_unevaluated_operand. */
19702 cp_evaluated ev;
19704 /* Fix the type of 'this'.
19705 For static and xobj member functions we use this to transport the
19706 lambda's closure type. It appears that in the regular case the
19707 object parameter is still pulled off, and then re-added again anyway.
19708 So perhaps we could do something better here? */
19712 tree inst = (oldtmpl
19717 {
19720 }
19726 /* Let finish_function set this. */
19732 else
19733 /* Still increment function_depth so that we don't GC in the
19734 middle of an expression. */
19744 /* Now record them for lookup_init_capture_pack. */
19747 {
19751 }
19757 {
19758 /* We might not partially instantiate some parts of the function, so
19759 copy these flags from the original template. */
19765 }
19767 /* [temp.deduct] A lambda-expression appearing in a function type or a
19768 template parameter is not considered part of the immediate context for
19769 the purposes of template argument deduction. */
19774 /* We already have a body block from start_lambda_function, we don't
19775 need another to confuse NRV (91217). */
19786 else
19789 /* The capture list was built up in reverse order; fix that now. */
19796 }
19798 out:
19804 }
19806 /* Subroutine of maybe_fold_fn_template_args. */
19808 static bool
19810 {
19813 {
19819 {
19822 }
19827 {
19831 }
19832 }
19835 }
19837 /* Try to do constant evaluation of any explicit template arguments in FN
19838 before overload resolution, to get any errors only once. Return true iff
19839 we didn't have any problems folding. */
19841 static bool
19843 {
19861 }
19863 /* Helper function for tsubst_expr CALL_EXPR and ARRAY_REF handling. */
19865 static void
19868 {
19871 {
19876 else
19877 {
19878 /* Expand the pack expansion and push each entry onto CALL_ARGS. */
19881 {
19886 {
19891 }
19892 }
19893 else
19894 /* A partial substitution. Add one entry. */
19896 }
19897 }
19898 }
19900 /* Like tsubst but deals with expressions and performs semantic
19901 analysis. */
19903 tree
19905 {
19906 #define RETURN(EXP) do { retval = (EXP); goto out; } while(0)
19907 #define RECUR(NODE) \
19908 tsubst_expr (NODE, args, complain, in_decl)
19911 location_t save_loc;
19920 /* N3276 decltype magic only applies to calls at the top level or on the
19921 right side of a comma. */
19925 /* This flag only applies to id-expressions at the top level, and
19926 controls resolution thereof. */
19935 {
19938 /* Fall through. */
19940 {
19941 tree decl;
19942 cp_id_kind idk;
19946 {
19949 }
19954 /* Look up the name. */
19957 /* By convention, expressions use ERROR_MARK_NODE to indicate
19958 failure, not NULL_TREE. */
19972 input_location);
19976 {
19980 }
19982 }
19985 {
19986 tree object;
19992 else
20001 {
20006 }
20009 {
20016 /* If we built a function concept check, return the underlying
20017 template-id. So we can evaluate it as a function call. */
20022 }
20025 {
20030 complain);
20034 }
20037 {
20040 }
20041 else
20053 {
20054 /* C++20 P0846: we can encounter an IDENTIFIER_NODE here when
20055 name lookup found nothing when parsing the template name. */
20058 }
20059 else
20061 }
20064 {
20068 {
20069 /* A type conversion to reference type will be enclosed in
20070 such an indirect ref, but the substitution of the cast
20071 will have also added such an indirect ref. */
20073 }
20074 else
20083 }
20086 {
20090 }
20093 {
20097 {
20102 }
20104 {
20109 }
20116 flags));
20117 }
20120 {
20126 }
20133 {
20134 tree type;
20148 {
20168 }
20171 }
20174 {
20178 }
20190 {
20193 }
20195 {
20199 }
20200 /* Fall through. */
20215 {
20222 }
20225 /* convert_like should have created an IMPLICIT_CONV_EXPR. */
20236 else
20238 in_decl);
20273 {
20274 /* If either OP0 or OP1 was value- or type-dependent, suppress
20275 warnings that depend on the range of the types involved. */
20289 tree r = build_x_binary_op
20291 op0,
20293 ? ERROR_MARK
20295 op1,
20297 ? ERROR_MARK
20306 }
20309 {
20317 }
20321 {
20326 }
20327 else
20341 {
20343 releasing_vec index_exp_list;
20346 tree r;
20352 else
20357 }
20363 {
20369 {
20373 }
20375 {
20379 }
20381 }
20386 {
20395 /* We only want to compute the number of arguments. */
20398 else
20405 {
20407 /* Set TREE_USED for the benefit of -Wunused. */
20411 }
20419 {
20422 else
20430 else
20435 }
20436 else
20438 }
20439 /* Fall through */
20442 {
20443 tree r;
20451 {
20452 /* When there are no ARGS, we are trying to evaluate a
20453 non-dependent expression from the parser. Trying to do
20454 the substitutions may not work. */
20457 }
20458 else
20459 {
20464 else
20468 }
20473 else
20478 {
20480 {
20482 {
20486 }
20487 else
20491 }
20493 }
20495 }
20498 {
20506 }
20520 {
20525 tree r = build_x_modify_expr
20529 /* TREE_NO_WARNING must be set if either the expression was
20530 parenthesized or it uses an operator such as >>= rather
20531 than plain assignment. In the former case, it was already
20532 set and must be copied. In the latter case,
20533 build_x_modify_expr sets it and it must not be reset
20534 here. */
20539 }
20544 /* Remember that there was a reference to this entity. */
20551 {
20556 tree ret;
20563 else
20564 {
20568 }
20570 /* If there was an initializer in the original tree, but it
20571 instantiated to an empty list, then we should pass a
20572 non-NULL empty vector to tell build_new that it was an
20573 empty initializer() rather than no initializer. This can
20574 only happen when the initializer is a pack expansion whose
20575 parameter packs are of length zero. */
20580 else
20581 {
20585 else
20586 {
20589 }
20590 }
20592 /* Avoid passing an enclosing decl to valid_array_size_p. */
20599 complain);
20607 }
20610 {
20616 complain));
20617 }
20620 {
20624 op0,
20628 }
20631 {
20632 tree function;
20636 tree ret;
20639 /* Internal function with no arguments. */
20643 /* When we parsed the expression, we determined whether or
20644 not Koenig lookup should be performed. */
20647 {
20650 }
20652 {
20657 }
20661 {
20663 in_decl);
20665 {
20672 }
20673 else
20676 }
20681 {
20682 /* Do nothing; calling tsubst_expr on an identifier
20683 would incorrectly perform unqualified lookup again.
20685 Note that we can also have an IDENTIFIER_NODE if the earlier
20686 unqualified lookup found a dependent local extern declaration
20687 (as per finish_call_expr); in that case koenig_p will be false
20688 and we do want to do the lookup again to find the substituted
20689 declaration. */
20694 }
20695 else
20696 {
20698 {
20704 }
20705 else
20710 /* Avoid error about taking the address of a constructor. */
20715 /* When KOENIG_P, we don't want to mark_used the callee before
20716 augmenting the overload set via ADL, so during this initial
20717 substitution we disable mark_used by setting tf_conv (68942). */
20723 }
20726 releasing_vec call_args;
20729 /* Stripped-down processing for a call in a thunk. Specifically, in
20730 the thunk template for a generic lambda. */
20732 {
20733 /* Now that we've expanded any packs, the number of call args
20734 might be different. */
20738 {
20745 }
20746 /* We aren't going to do normal overload resolution, so force the
20747 template-id to resolve. */
20750 {
20751 /* In a thunk, pass through args directly, without any
20752 conversions. */
20757 }
20759 {
20760 /* If there are no other args, just push 'this'. */
20763 else
20764 {
20765 /* Otherwise, shift the other args over to make room. */
20771 }
20772 }
20775 /* The thunk location is not interesting. */
20782 }
20784 /* We do not perform argument-dependent lookup if normal
20785 lookup finds a non-function, in accordance with the
20786 resolution of DR 218. */
20789 /* If lookup found a member function, the Koenig lookup is
20790 not appropriate, even if an unqualified-name was used
20791 to denote the function. */
20794 /* C++20 P0846: Lookup found nothing. */
20797 /* Only do this when substitution turns a dependent call
20798 into a non-dependent call. */
20810 {
20815 {
20816 /* For backwards compatibility and good diagnostics, try
20817 the unqualified lookup again if we aren't in SFINAE
20818 context. */
20824 {
20827 "and no declarations were found by "
20828 "argument-dependent lookup at the point "
20833 /* In a lambda fn, we have to be careful to not
20834 introduce new this captures. Legacy code can't
20835 be using lambdas anyway, so it's ok to be
20836 stricter. Be strict with C++20 template-id ADL too.
20837 And be strict if we're already failing anyway. */
20843 else
20847 {
20858 {
20861 "declarations in dependent base %qT are "
20867 else
20871 }
20872 else
20874 "%qD declared here, later in the "
20878 }
20881 }
20882 }
20884 {
20888 }
20889 }
20891 /* Remember that there was a reference to this entity. */
20900 /* Put back tf_decltype for the actual call. */
20905 {
20909 {
20911 "wrong number of arguments to "
20914 }
20915 else
20923 {
20925 "wrong number of arguments to "
20929 }
20933 complain);
20939 {
20941 complain);
20945 }
20950 {
20952 "wrong number of arguments to "
20955 }
20956 else
20957 {
20962 {
20965 }
20968 }
20972 /* Unsupported internal function with arguments. */
20974 }
20979 complain);
20981 {
20982 /* FUNCTION is a template-id referring to a concept definition. */
20987 /* Calls to standard and variable concepts should have been
20988 previously diagnosed. */
20991 /* Ensure the result is wrapped as a call expression. */
20993 }
20994 else
20997 koenig_p,
20998 complain);
21001 {
21007 {
21011 }
21013 /* This also suppresses -Wredundant-move. */
21015 }
21018 }
21021 {
21028 {
21030 {
21035 }
21036 else
21037 {
21042 }
21044 }
21045 else
21046 {
21049 }
21054 }
21057 {
21062 input_location));
21063 }
21069 {
21070 tree object;
21071 tree object_type;
21072 tree member;
21073 tree r;
21077 /* Remember that there was a reference to this entity. */
21088 else
21095 {
21098 }
21100 {
21102 complain);
21106 }
21110 {
21112 {
21117 {
21120 }
21122 {
21127 }
21128 }
21129 }
21132 {
21133 /* Lookup the template functions now that we know what the
21134 scope is. */
21141 {
21144 args);
21145 member = (adjust_result_of_qualified_name_lookup
21147 object_type));
21148 }
21149 else
21150 {
21152 input_location);
21154 }
21155 }
21159 {
21161 {
21165 else
21168 }
21170 }
21174 complain);
21178 }
21185 {
21192 tree r;
21201 /* We do not want to process the index of aggregate
21202 initializers as they are identifier nodes which will be
21203 looked up by digest_init. */
21207 {
21210 }
21215 {
21217 /* An identifier index is looked up in the type
21218 being initialized, not the current scope. */
21223 {
21224 /* Substitute into the pack expansion. */
21226 in_decl);
21230 ;
21232 /* Just move the argument into place. */
21234 else
21235 {
21236 /* Update the length of the final CONSTRUCTOR
21237 arguments vector, and note that we will need to
21238 copy.*/
21241 }
21242 }
21243 else
21245 }
21248 {
21253 {
21255 {
21260 }
21261 else
21263 }
21264 }
21272 {
21277 }
21281 }
21284 {
21287 {
21290 }
21291 else
21292 {
21295 }
21296 }
21303 tree r;
21308 {
21309 /* Local specialization will usually have been created when
21310 we instantiated the DECL_EXPR_DECL. */
21313 {
21314 /* We're in a generic lambda referencing a local extern
21315 from an outer block-scope of a non-template. */
21318 }
21319 }
21324 {
21326 {
21327 /* We get here for a use of 'this' in an NSDMI. */
21331 /* This can happen for a parameter name used later in a function
21332 declaration (such as in a late-specified return type). Just
21333 make a dummy decl, since it's only used for its type. */
21336 /* Give it the template pattern as its context; its true context
21337 hasn't been instantiated yet and this is good enough for
21338 mangling. */
21340 }
21342 {
21343 /* First try name lookup to find the instantiation. */
21346 {
21348 {
21349 /* During error-recovery we may find a non-variable,
21350 even an OVERLOAD: just bail out and avoid ICEs and
21351 duplicate diagnostics (c++/62207). */
21354 }
21356 {
21357 /* Make sure the one we found is the one we want. */
21361 }
21362 }
21366 else
21367 {
21368 /* This can happen for a variable used in a
21369 late-specified return type of a local lambda, or for a
21370 local static or constant. Building a new VAR_DECL
21371 should be OK in all those cases. */
21374 /* Avoid infinite recursion (79640). */
21377 {
21378 /* We can't call cp_finish_decl, so handle the
21379 initializer by hand. */
21394 }
21396 || processing_contract_condition
21403 }
21404 /* Remember this for subsequent uses. */
21407 }
21410 }
21411 else
21418 {
21419 /* ??? We're doing a subset of finish_id_expression here. */
21421 /* Replace an evaluated use of the thread_local variable with
21422 a call to its wrapper. */
21428 /* If the original type was a reference, we'll be wrapped in
21429 the appropriate INDIRECT_REF. */
21431 }
21435 {
21436 tree enum_type;
21437 tree v;
21444 /* Unfortunately, we cannot just call lookup_name here.
21445 Consider:
21447 template <int I> int f() {
21448 enum E { a = I };
21449 struct S { void g() { E e = a; } };
21450 };
21452 When we instantiate f<7>::S::g(), say, lookup_name is not
21453 clever enough to find f<7>::a. */
21454 enum_type
21464 /* We didn't find the name. That should never happen; if
21465 name-lookup found it during preliminary parsing, we
21466 should find it again here during instantiation. */
21469 }
21473 {
21474 tree ctx;
21479 {
21482 {
21486 }
21488 }
21489 }
21504 {
21505 /* Template template argument like the following example need
21506 special treatment:
21508 template <template <class> class TT> struct C {};
21509 template <class T> struct D {
21510 template <class U> struct E {};
21511 C<E> c; // #1
21512 };
21513 D<int> d; // #2
21515 We are processing the template argument `E' in #1 for
21516 the template instantiation #2. Originally, `E' is a
21517 TEMPLATE_DECL with `D<T>' as its DECL_CONTEXT. Now we
21518 have to substitute this with one having context `D<int>'. */
21523 }
21524 else
21525 /* Ordinary template template argument. */
21533 /* We shouldn't have built any of these during initial template
21534 generation. Instead, they should be built during instantiation
21535 in response to the saved STMT_IS_FULL_EXPR_P setting. */
21539 {
21549 }
21567 {
21568 /* Instantiate any typedefs in the type. */
21573 }
21576 {
21580 {
21583 }
21585 }
21588 /* These can sometimes show up in a partial instantiation, but never
21589 involve template parms. */
21605 /* ??? There's no point in copying it for now, but maybe some
21606 day it will contain more information, such as a pointer back
21607 to the containing function, inlined copy or so. */
21619 {
21623 }
21626 {
21627 tree object_ptr
21632 }
21639 {
21643 else
21649 }
21652 {
21661 /* If the resulting list of expression statement is empty,
21662 fold it further into void_node. */
21667 }
21670 {
21672 {
21673 /* We don't have a full set of template arguments yet; don't touch
21674 the lambda at all. */
21677 }
21681 }
21690 else
21691 /* Recreate the PAREN_EXPR from __builtin_assoc_barrier. */
21692 {
21696 }
21699 {
21704 complain));
21705 }
21708 {
21712 }
21715 /* No need to substitute further, a RANGE_EXPR will always be built
21716 with constant operands. */
21721 {
21725 /* We need to do this here as well as in tsubst_copy so we get the
21726 other tsubst_copy_and_build semantics for a PARM_DECL operand. */
21731 /* force_paren_expr can also create a VIEW_CONVERT_EXPR. */
21734 /* Otherwise, we're dealing with a wrapper to make a C++20 template
21735 parameter object const. */
21738 {
21739 /* The template argument is not const, presumably because
21740 it is still dependent, and so not the const template parm
21741 object. */
21745 {
21746 /* Don't add a wrapper to these. */
21749 }
21750 else
21751 /* Do add a wrapper otherwise (in particular, if op is
21752 another TEMPLATE_PARM_INDEX). */
21754 }
21756 }
21759 {
21766 op3);
21769 }
21772 /* Handle Objective-C++ constructs, if appropriate. */
21776 /* We shouldn't get here, but keep going if !flag_checking. */
21780 }
21782 #undef RECUR
21783 #undef RETURN
21784 out:
21787 }
21789 /* Verify that the instantiated ARGS are valid. For type arguments,
21790 make sure that the type's linkage is ok. For non-type arguments,
21791 make sure they are constants if they are integral or enumerations.
21792 Emit an error under control of COMPLAIN, and return TRUE on error. */
21794 static bool
21796 {
21800 {
21810 }
21812 {
21813 /* [basic.link]: A name with no linkage (notably, the name
21814 of a class or enumeration declared in a local scope)
21815 shall not be used to declare an entity with linkage.
21816 This implies that names with no linkage cannot be used as
21817 template arguments
21819 DR 757 relaxes this restriction for C++0x. */
21824 {
21825 /* DR 488 makes use of a type with no linkage cause
21826 type deduction to fail. */
21828 {
21831 else
21834 }
21836 }
21837 /* In order to avoid all sorts of complications, we do not
21838 allow variably-modified types as template arguments. */
21840 {
21844 }
21845 }
21846 /* Class template and alias template arguments should be OK. */
21848 ;
21849 /* A non-type argument of integral or enumerated type must be a
21850 constant. */
21855 {
21859 }
21861 }
21863 static bool
21865 {
21870 {
21873 }
21877 }
21879 /* Call mark_used on each entity within the non-type template arguments in
21880 ARGS for an instantiation of TMPL, to ensure that each such entity is
21881 considered odr-used (and therefore marked for instantiation) regardless of
21882 whether the specialization was first formed in a template context (which
21883 inhibits mark_used).
21885 This function assumes push_to_top_level has been called beforehand. */
21887 static void
21889 {
21890 /* It suffices to do this only when instantiating a primary template. */
21894 /* We already marked outer arguments when specializing the context. */
21898 {
21899 /* A (pointer/reference to) function or variable NTTP argument. */
21902 {
21908 {
21909 /* Pass tf_none to avoid duplicate diagnostics: if this call
21910 fails then an earlier call to mark_used for this argument
21911 must have also failed and emitted a diagnostic. */
21914 }
21915 }
21916 /* A class NTTP argument. */
21919 {
21922 {
21925 }
21927 };
21930 }
21931 }
21932 }
21934 /* We're out of SFINAE context now, so generate diagnostics for the access
21935 errors we saw earlier when instantiating D from TMPL and ARGS. */
21937 static void
21939 {
21951 }
21953 /* Instantiate the indicated variable, function, or alias template TMPL with
21954 the template arguments in TARG_PTR. */
21956 tree
21958 {
21962 tree fndecl;
21963 tree gen_tmpl;
21969 /* The other flags are not relevant anymore here, especially tf_partial
21970 shouldn't be set. For instance, we may be called while doing a partial
21971 substitution of a template variable, but the type of the variable
21972 template may be auto, in which case we will call do_auto_deduction
21973 in mark_used (which clears tf_partial) and the auto must be properly
21974 reduced at that time for the deduction to work. */
21982 /* If this function is a clone, handle it specially. */
21984 {
21985 tree spec;
21986 tree clone;
21988 /* Use DECL_ABSTRACT_ORIGIN because only FUNCTION_DECLs have
21989 DECL_CLONED_FUNCTION. */
21995 /* Look for the clone. */
21999 /* We should always have found the clone by now. */
22002 }
22007 /* Check to see if we already have this specialization. */
22011 /* targ_ptr only has the innermost template args, so add the outer ones
22012 from tmpl, which could be either a partial instantiation or gen_tmpl (in
22013 the case of a non-dependent call within a template definition). */
22014 targ_ptr = (add_outermost_template_args
22016 targ_ptr));
22022 || ((fndecl
22028 {
22030 {
22034 }
22036 }
22039 complain))
22042 /* We are building a FUNCTION_DECL, during which the access of its
22043 parameters and return types have to be checked. However this
22044 FUNCTION_DECL which is the desired context for access checking
22045 is not built yet. We solve this chicken-and-egg problem by
22046 deferring all checks until we have the FUNCTION_DECL. */
22049 /* Instantiation of the function happens in the context of the function
22050 template, not the context of the overload resolution we're doing. */
22052 /* If there are dependent arguments, e.g. because we're doing partial
22053 ordering, make sure processing_template_decl stays set. */
22057 {
22058 tree ctx;
22060 /* If the context of the partially instantiated template is
22061 already non-dependent, then we might as well use it. */
22063 else
22067 }
22074 {
22075 /* We need to determine if we're using a partial or explicit
22076 specialization now, because the type of the variable could be
22077 different. */
22083 {
22089 }
22090 }
22092 /* Substitute template parameters to obtain the specialization. */
22100 {
22103 }
22105 /* The DECL_TI_TEMPLATE should always be the immediate parent
22106 template, not the most general template. */
22110 {
22111 /* Now that we we've formed this variable template specialization,
22112 remember the result of most_specialized_partial_spec for it. */
22115 /* And remember if the variable was declared with []. */
22119 }
22127 /* Now we know the specialization, compute access previously
22128 deferred. Do no access control for inheriting constructors,
22129 as we already checked access for the inherited constructor. */
22132 {
22137 }
22140 /* If we've just instantiated the main entry point for a function,
22141 instantiate all the alternate entry points as well. We do this
22142 by cloning the instantiation of the main entry point, not by
22143 instantiating the template clones. */
22149 {
22151 {
22152 /* Remember to reinstantiate when we're out of SFINAE so the user
22153 can see the errors. */
22155 }
22157 }
22160 }
22162 /* Instantiate the alias template TMPL with ARGS. Also push a template
22163 instantiation level, which instantiate_template doesn't do because
22164 functions and variables have sufficient context established by the
22165 callers. */
22167 static tree
22169 {
22178 /* FIXME check for satisfaction in check_instantiated_args. */
22180 {
22182 {
22183 auto_diagnostic_group d;
22186 }
22188 }
22196 {
22197 /* An alias template specialization can be dependent
22198 even if its underlying type is not. */
22201 /* Sometimes a dependent alias spec is equivalent to its expansion,
22202 sometimes not. So always use structural_comptypes. */
22204 }
22207 }
22209 /* PARM is a template parameter pack for FN. Returns true iff
22210 PARM is used in a deducible way in the argument list of FN. */
22212 static bool
22214 {
22217 {
22219 tree packs;
22225 {
22226 /* The template parameter pack is used in a function parameter
22227 pack. If this is the end of the parameter list, the
22228 template parameter pack is deducible. */
22231 else
22232 /* Otherwise, not. Well, it could be deduced from
22233 a non-pack parameter, but doing so would end up with
22234 a deduction mismatch, so don't bother. */
22236 }
22237 }
22238 /* The template parameter pack isn't used in any function parameter
22239 packs, but it might be used deeper, e.g. tuple<Args...>. */
22241 }
22243 /* Subroutine of fn_type_unification: check non-dependent parms for
22244 convertibility. */
22246 static int
22251 {
22252 /* Non-constructor methods need to leave a conversion for 'this', which
22253 isn't included in nargs here. */
22259 {
22265 /* For a function parameter pack that occurs at the end of the
22266 parameter-declaration-list, the type A of each remaining
22267 argument of the call is compared with the type P of the
22268 declarator-id of the function parameter pack. */
22274 /* For a function parameter pack that does not occur at the
22275 end of the parameter-declaration-list, the type of the
22276 parameter pack is a non-deduced context. */
22280 {
22288 }
22291 }
22294 }
22296 /* The FN is a TEMPLATE_DECL for a function. ARGS is an array with
22297 NARGS elements of the arguments that are being used when calling
22298 it. TARGS is a vector into which the deduced template arguments
22299 are placed.
22301 Returns either a FUNCTION_DECL for the matching specialization of FN or
22302 NULL_TREE if no suitable specialization can be found. If EXPLAIN_P is
22303 true, diagnostics will be printed to explain why it failed.
22305 If FN is a conversion operator, or we are trying to produce a specific
22306 specialization, RETURN_TYPE is the return type desired.
22308 The EXPLICIT_TARGS are explicit template arguments provided via a
22309 template-id.
22311 The parameter STRICT is one of:
22313 DEDUCE_CALL:
22314 We are deducing arguments for a function call, as in
22315 [temp.deduct.call]. If RETURN_TYPE is non-null, we are
22316 deducing arguments for a call to the result of a conversion
22317 function template, as in [over.call.object].
22319 DEDUCE_CONV:
22320 We are deducing arguments for a conversion function, as in
22321 [temp.deduct.conv].
22323 DEDUCE_EXACT:
22324 We are deducing arguments when doing an explicit instantiation
22325 as in [temp.explicit], when determining an explicit specialization
22326 as in [temp.expl.spec], or when taking the address of a function
22327 template, as in [temp.deduct.funcaddr]. */
22329 tree
22331 tree explicit_targs,
22332 tree targs,
22335 tree return_type,
22336 unification_kind_t strict,
22341 {
22342 tree parms;
22343 tree fntype;
22348 /* type_unification_real will pass back any access checks from default
22349 template argument substitution. */
22351 /* We don't have all the template args yet. */
22364 full_targs = (add_outermost_template_args
22366 targs));
22371 /* In C++0x, it's possible to have a function template whose type depends
22372 on itself recursively. This is most obvious with decltype, but can also
22373 occur with enumeration scope (c++/48969). So we need to catch infinite
22374 recursion and reject the substitution at deduction time; this function
22375 will return error_mark_node for any repeated substitution.
22377 This also catches excessive recursion such as when f<N> depends on
22378 f<N-1> across all integers, and returns error_mark_node for all the
22379 substitutions back up to the initial one.
22381 This is, of course, not reentrant. */
22390 {
22391 /* [temp.deduct]
22393 The specified template arguments must match the template
22394 parameters in kind (i.e., type, nontype, template), and there
22395 must not be more arguments than there are parameters;
22396 otherwise type deduction fails.
22398 Nontype arguments must match the types of the corresponding
22399 nontype template parameters, or must be convertible to the
22400 types of the corresponding nontype parameters as specified in
22401 _temp.arg.nontype_, otherwise type deduction fails.
22403 All references in the function type of the function template
22404 to the corresponding template parameters are replaced by the
22405 specified template argument values. If a substitution in a
22406 template parameter or in the function type of the function
22407 template results in an invalid type, type deduction fails. */
22418 explicit_targs);
22420 /* Adjust any explicit template arguments before entering the
22421 substitution context. */
22422 explicit_targs
22429 /* Substitute the explicit args into the function type. This is
22430 necessary so that, for instance, explicitly declared function
22431 arguments can match null pointed constants. If we were given
22432 an incomplete set of explicit args, we must not do semantic
22433 processing during substitution as we could create partial
22434 instantiations. */
22436 {
22441 /* Dig out the actual parm. */
22444 {
22447 }
22449 {
22452 }
22455 /* No explicit argument for this template parameter. */
22458 {
22459 /* Mark the argument pack as "incomplete". We could
22460 still deduce more arguments during unification.
22461 We remove this mark in type_unification_real. */
22466 /* We have some incomplete argument packs. */
22468 }
22469 }
22472 {
22474 {
22477 }
22480 /* Ignore any access checks; we'll see them again in
22481 instantiate_template and they might have the wrong
22482 access path at this point. */
22493 }
22495 /* Place the explicitly specified arguments in TARGS. */
22501 SET_NON_DEFAULT_TEMPLATE_ARGS_COUNT
22503 }
22506 {
22512 }
22517 /* Never do unification on the 'this' parameter. */
22521 {
22522 /* We're deducing for a call to the result of a template conversion
22523 function. The parms we really want are in return_type. */
22527 }
22529 {
22531 }
22533 /* We allow incomplete unification without an error message here
22534 because the standard doesn't seem to explicitly prohibit it. Our
22535 callers must be ready to deal with unification failures in any
22536 event. */
22538 /* If we aren't explaining yet, push tinst context so we can see where
22539 any errors (e.g. from class instantiations triggered by instantiation
22540 of default template arguments) come from. If we are explaining, this
22541 context is redundant. */
22543 {
22546 }
22556 /* Now that we have bindings for all of the template arguments,
22557 ensure that the arguments deduced for the template template
22558 parameters have compatible template parameter lists. We cannot
22559 check this property before we have deduced all template
22560 arguments, because the template parameter types of a template
22561 template parameter might depend on prior template parameters
22562 deduced after the template template parameter. The following
22563 ill-formed example illustrates this issue:
22565 template<typename T, template<T> class C> void f(C<5>, T);
22567 template<int N> struct X {};
22569 void g() {
22570 f(X<5>(), 5l); // error: template argument deduction fails
22571 }
22573 The template parameter list of 'C' depends on the template type
22574 parameter 'T', but 'C' is deduced to 'X' before 'T' is deduced to
22575 'long'. Thus, we can't check that 'C' cannot bind to 'X' at the
22576 time that we deduce 'C'. */
22579 {
22582 }
22584 deduced:
22586 /* As a refinement of CWG2369, check first and foremost non-dependent
22587 conversions that we know are not going to induce template instantiation
22588 (PR99599). */
22590 && incomplete
22596 /* CWG2369: Check satisfaction before non-deducible conversions. */
22598 {
22602 }
22604 /* DR 1391: All parameters have args, now check non-dependent parms for
22605 convertibility. We don't do this if all args were explicitly specified,
22606 as the standard says that we substitute explicit args immediately. */
22613 /* All is well so far. Now, check:
22615 [temp.deduct]
22617 When all template arguments have been deduced, all uses of
22618 template parameters in nondeduced contexts are replaced with
22619 the corresponding deduced argument values. If the
22620 substitution results in an invalid type, as described above,
22621 type deduction fails. */
22623 {
22626 }
22628 /* Also collect access checks from the instantiation. */
22641 /* Now perform any access checks encountered during substitution. */
22648 /* If we're looking for an exact match, check that what we got
22649 is indeed an exact match. It might not be if some template
22650 parameters are used in non-deduced contexts. But don't check
22651 for an exact match if we have dependent template arguments;
22652 in that case we're doing partial ordering, and we already know
22653 that we have two candidates that will provide the actual type. */
22655 {
22659 tree sarg
22665 {
22669 }
22671 /* add_candidates uses DEDUCE_EXACT for x.operator foo(), but args
22672 doesn't contain the trailing void, and conv fns are always (). */
22674 {
22678 }
22679 }
22681 /* After doing deduction with the inherited constructor, actually return an
22682 instantiation of the inheriting constructor. */
22688 fail:
22691 {
22693 /* Reset once we're all the way out. */
22695 }
22698 }
22700 /* Returns true iff PARM is a forwarding reference in the context of
22701 template argument deduction for TMPL. */
22703 static bool
22705 {
22706 /* [temp.deduct.call], "A forwarding reference is an rvalue reference to a
22707 cv-unqualified template parameter ..." */
22712 {
22714 /* [temp.deduct.call], "... that does not represent a template parameter
22715 of a class template (during class template argument deduction)." */
22719 {
22720 /* Since the template parameters of a synthesized guide consist of
22721 the template parameters of the class template followed by those of
22722 the constructor (if any), we can tell if PARM represents a template
22723 parameter of the class template by comparing its index with the
22724 arity of the class template. */
22729 }
22731 }
22733 }
22735 /* Adjust types before performing type deduction, as described in
22736 [temp.deduct.call] and [temp.deduct.conv]. The rules in these two
22737 sections are symmetric. PARM is the type of a function parameter
22738 or the return type of the conversion function. ARG is the type of
22739 the argument passed to the call, or the type of the value
22740 initialized with the result of the conversion function.
22741 ARG_EXPR is the original argument expression, which may be null. */
22743 static int
22745 unification_kind_t strict,
22748 tree arg_expr)
22749 {
22753 {
22758 /* [temp.deduct.conv] First remove a reference type on parm.
22759 DRs 322 & 976 affected this. */
22763 /* Swap PARM and ARG throughout the remainder of this
22764 function; the handling is precisely symmetric since PARM
22765 will initialize ARG rather than vice versa. */
22771 /* Core issue #873: Do the DR606 thing (see below) for these cases,
22772 too, but here handle it by stripping the reference from PARM
22773 rather than by adding it to ARG. */
22778 /* Nothing else to do in this case. */
22783 }
22786 {
22787 /* [temp.deduct.call]
22789 If P is not a reference type:
22791 --If A is an array type, the pointer type produced by the
22792 array-to-pointer standard conversion (_conv.array_) is
22793 used in place of A for type deduction; otherwise,
22795 --If A is a function type, the pointer type produced by
22796 the function-to-pointer standard conversion
22797 (_conv.func_) is used in place of A for type deduction;
22798 otherwise,
22800 --If A is a cv-qualified type, the top level
22801 cv-qualifiers of A's type are ignored for type
22802 deduction. */
22807 else
22809 }
22811 /* [temp.deduct.call], "If P is a forwarding reference and the argument is
22812 an lvalue, the type 'lvalue reference to A' is used in place of A for
22813 type deduction." */
22816 /* try_one_overload doesn't provide an arg_expr, but
22817 functions are always lvalues. */
22821 /* [temp.deduct.call]
22823 If P is a cv-qualified type, the top level cv-qualifiers
22824 of P's type are ignored for type deduction. If P is a
22825 reference type, the type referred to by P is used for
22826 type deduction. */
22829 {
22832 }
22835 }
22837 /* Return true if computing a conversion from FROM to TO might induce template
22838 instantiation. Conversely, if this predicate returns false then computing
22839 the conversion definitely won't induce template instantiation. */
22841 static bool
22843 {
22850 {
22854 }
22856 /* If one of the types is a not-yet-instantiated class template
22857 specialization, then computing the conversion might instantiate
22858 it in order to inspect bases, conversion functions and/or
22859 converting constructors. */
22868 /* Converting from one pointer type to another, or between
22869 reference-related types, always yields a standard conversion. */
22873 /* Converting to a non-aggregate class type will consider its
22874 user-declared constructors, which might induce instantiation. */
22879 /* Similarly, converting from a class type will consider its conversion
22880 functions. */
22885 /* Otherwise, computing this conversion definitely won't induce
22886 template instantiation. */
22888 }
22890 /* Subroutine of fn_type_unification. PARM is a function parameter of a
22891 template which doesn't contain any deducible template parameters; check if
22892 ARG is a suitable match for it. STRICT, FLAGS and EXPLAIN_P are as in
22893 unify_one_argument. */
22895 static int
22899 {
22900 tree type;
22904 else
22912 {
22915 }
22917 {
22919 {
22920 /* This conversion was already computed earlier (when
22921 computing only non-instantiating conversions). */
22924 }
22933 /* Avoid recalculating this in add_function_candidate. */
22934 ok = (*conv_p
22936 else
22940 }
22944 else
22946 }
22950 /* Returns true iff the expression EXPR is one from which a template
22951 argument can be deduced. In other words, if it's an undecorated
22952 use of a template non-type parameter. */
22954 static bool
22956 {
22957 /* Strip implicit conversions and implicit INDIRECT_REFs. */
22963 }
22965 /* Returns true iff the array domain DOMAIN uses a template parameter in a
22966 deducible way; that is, if it has a max value of <PARM> - 1. */
22968 static bool
22970 {
22979 }
22981 /* Returns true iff the template arguments ARGS use a template parameter
22982 in a deducible way. */
22984 static bool
22986 {
22988 {
22992 else
22993 {
23000 else
23002 }
23005 }
23007 }
23009 /* Returns true iff TYPE contains any deducible references to template
23010 parameters, as per 14.8.2.5. */
23012 static bool
23014 {
23018 /* T
23019 cv-list T
23020 TT<T>
23021 TT<i>
23022 TT<> */
23027 /* T*
23028 T&
23029 T&& */
23033 /* T[integer-constant ]
23034 type [i] */
23039 /* T type ::*
23040 type T::*
23041 T T::*
23042 T (type ::*)()
23043 type (T::*)()
23044 type (type ::*)(T)
23045 type (T::*)(T)
23046 T (type ::*)(T)
23047 T (T::*)()
23048 T (T::*)(T) */
23051 || (uses_deducible_template_parms
23054 /* template-name <T> (where template-name refers to a class template)
23055 template-name <i> (where template-name refers to a class template) */
23062 /* type (T)
23063 T()
23064 T(T) */
23066 {
23080 }
23083 }
23085 /* Subroutine of type_unification_real and unify_pack_expansion to
23086 handle unification of a single P/A pair. Parameters are as
23087 for those functions. */
23089 static int
23093 {
23100 /* We can't deduce anything from this, but we might get all the
23101 template args from other function args. */
23104 /* Implicit conversions (Clause 4) will be performed on a function
23105 argument to convert it to the type of the corresponding function
23106 parameter if the parameter type contains no template-parameters that
23107 participate in template argument deduction. */
23110 /* For function parameters with no deducible template parameters,
23111 just return. We'll check non-dependent conversions later. */
23115 {
23117 arg_strict = (UNIFY_ALLOW_OUTER_LEVEL
23118 | UNIFY_ALLOW_MORE_CV_QUAL
23132 }
23134 /* We only do these transformations if this is the top-level
23135 parameter_type_list in a call or declaration matching; in other
23136 situations (nested function declarators, template argument lists) we
23137 won't be comparing a type to an expression, and we don't do any type
23138 adjustments. */
23140 {
23142 {
23145 {
23146 /* [temp.deduct.type] A template-argument can be
23147 deduced from a pointer to function or pointer
23148 to member function argument if the set of
23149 overloaded functions does not contain function
23150 templates and at most one of a set of
23151 overloaded functions provides a unique
23152 match. */
23156 /* If a unique match was not found, this is a
23157 non-deduced context, so we still succeed. */
23159 }
23165 }
23169 }
23170 else
23175 /* For deduction from an init-list we need the actual list. */
23179 }
23181 /* for_each_template_parm callback that always returns 0. */
23183 static int
23185 {
23187 }
23189 /* for_each_template_parm any_fn callback to handle deduction of a template
23190 type argument from the type of an array bound. */
23192 static int
23194 {
23202 {
23208 }
23210 /* Keep walking. */
23212 }
23214 /* Try to deduce any not-yet-deduced template type arguments from the type of
23215 an array bound. This is handled separately from unify because 14.8.2.5 says
23216 "The type of a type parameter is only deduced from an array bound if it is
23217 not otherwise deduced." */
23219 static void
23221 {
23226 }
23228 /* Most parms like fn_type_unification.
23230 If SUBR is 1, we're being called recursively (to unify the
23231 arguments of a function or method parameter of a function
23232 template).
23234 CHECKS is a pointer to a vector of access checks encountered while
23235 substituting default template arguments. */
23237 static int
23239 tree full_targs,
23240 tree xparms,
23244 unification_kind_t strict,
23247 {
23252 tree parms;
23263 /* Reset the number of non-defaulted template arguments contained
23264 in TARGS. */
23267 again:
23272 /* Only fn_type_unification cares about terminal void. */
23279 {
23284 /* For a function parameter pack that occurs at the end of the
23285 parameter-declaration-list, the type A of each remaining
23286 argument of the call is compared with the type P of the
23287 declarator-id of the function parameter pack. */
23293 /* For a function parameter pack that does not occur at the
23294 end of the parameter-declaration-list, the type of the
23295 parameter pack is a non-deduced context. */
23302 explain_p))
23304 }
23309 {
23310 /* Unify the remaining arguments with the pack expansion type. */
23311 tree argvec;
23314 /* Allocate a TREE_VEC and copy in all of the arguments */
23319 /* Copy the parameter into parmvec. */
23325 /* Advance to the end of the list of parameters. */
23327 }
23329 /* Fail if we've reached the end of the parm list, and more args
23330 are present, and the parm list isn't variadic. */
23333 /* Fail if parms are left and they don't have default values and
23334 they aren't all deduced as empty packs (c++/57397). This is
23335 consistent with sufficient_parms_p. */
23338 {
23342 do
23343 {
23346 count++;
23348 }
23352 type_pack_p);
23353 }
23356 {
23357 tsubst_flags_t complain = (explain_p
23358 ? tf_warning_or_error
23363 {
23367 /* Clear the "incomplete" flags on all argument packs now so that
23368 substituting them into later default arguments works. */
23370 {
23373 }
23381 {
23386 }
23388 /* If this is an undeduced nontype parameter that depends on
23389 a type parameter, try another pass; its type may have been
23390 deduced from a later argument than the one from which
23391 this parameter can be deduced. */
23396 {
23399 }
23401 /* Core issue #226 (C++0x) [temp.deduct]:
23403 If a template argument has not been deduced, its
23404 default template argument, if any, is used.
23406 When we are in C++98 mode, TREE_PURPOSE will either
23407 be NULL_TREE or ERROR_MARK_NODE, so we do not need
23408 to explicitly check cxx_dialect here. */
23410 /* OK, there is a default argument. Wait until after the
23411 conversion check to do substitution. */
23414 /* If the type parameter is a parameter pack, then it will
23415 be deduced to an empty parameter pack. */
23417 {
23418 tree arg;
23421 {
23424 }
23425 else
23432 }
23435 }
23437 /* During partial ordering, we deduce dependent template args. */
23440 /* Now substitute into the default template arguments. */
23442 {
23447 {
23451 }
23466 {
23467 /* The type of this non-type parameter depends on undeduced
23468 parameters. Don't try to use its default argument yet,
23469 since we might deduce an argument for it on the next pass,
23470 but do check whether the arguments we already have cause
23471 substitution failure, so that that happens before we try
23472 later default arguments (78489). */
23475 NULL_TREE);
23479 else
23481 }
23482 else
23483 {
23484 /* Even if the call is happening in template context, getting
23485 here means it's non-dependent, and a default argument is
23486 considered a separate definition under [temp.decls], so we can
23487 do this substitution without processing_template_decl. This
23488 is important if the default argument contains something that
23489 might be instantiation-dependent like access (87480). */
23493 {
23494 /* First instatiate in template context, in case we still
23495 depend on undeduced template parameters. */
23498 NULL_TREE);
23502 /* We replaced all the tparms, substitute again out of
23503 template context. */
23505 }
23508 NULL_TREE);
23517 }
23526 {
23528 /* The position of the first default template argument,
23529 is also the number of non-defaulted arguments in TARGS.
23530 Record that. */
23533 }
23534 }
23538 }
23544 }
23546 /* Subroutine of type_unification_real. Args are like the variables
23547 at the call site. ARG is an overloaded function (or template-id);
23548 we try deducing template args from each of the overloads, and if
23549 only one succeeds, we go with that. Modifies TARGS and returns
23550 true on success. */
23552 static bool
23554 tree targs,
23555 tree parm,
23556 tree arg,
23557 unification_kind_t strict,
23560 {
23567 {
23570 }
23571 else
23575 /* Handle `&x' where `x' is some static or non-static member
23576 function name. */
23582 /* Strip baselink information. */
23587 {
23588 /* If we got some explicit template args, we need to plug them into
23589 the affected templates before we try to unify, in case the
23590 explicit args will completely resolve the templates in question. */
23597 {
23608 {
23613 {
23614 /* Instantiate the function to deduce its return type. */
23618 }
23627 {
23630 }
23631 }
23634 }
23635 /* If no templates (or more than one) are fully resolved by the
23636 explicit arguments, this template-id is a non-deduced context; it
23637 could still be OK if we deduce all template arguments for the
23638 enclosing call through other arguments. */
23641 }
23643 /* If ARG is, for example, "(0, &f)" then its type will be unknown
23644 -- but the deduction does not succeed because the expression is
23645 not just the function on its own. */
23647 else
23649 {
23654 {
23657 }
23658 }
23660 /* [temp.deduct.type] A template-argument can be deduced from a pointer
23661 to function or pointer to member function argument if the set of
23662 overloaded functions does not contain function templates and at most
23663 one of a set of overloaded functions provides a unique match.
23665 So if we found multiple possibilities, we return success but don't
23666 deduce anything. */
23669 {
23673 {
23678 /* Don't forget explicit template arguments in a pack. */
23682 }
23683 }
23688 }
23690 /* Core DR 115: In contexts where deduction is done and fails, or in
23691 contexts where deduction is not done, if a template argument list is
23692 specified and it, along with any default template arguments, identifies
23693 a single function template specialization, then the template-id is an
23694 lvalue for the function template specialization. */
23696 tree
23698 {
23711 {
23714 }
23716 {
23719 }
23721 {
23724 }
23727 {
23731 /* If we got some explicit template args, we need to plug them into
23732 the affected templates before we try to unify, in case the
23733 explicit args will completely resolve the templates in question. */
23741 {
23752 {
23755 {
23758 }
23761 {
23764 }
23765 }
23766 }
23768 {
23776 {
23777 tree base
23780 }
23784 }
23786 /* There were no good options and at least one bad one, so let the
23787 user know what the problem is. */
23789 }
23791 }
23793 /* As above, but error out if the expression remains overloaded. */
23795 tree
23797 {
23800 {
23804 }
23806 }
23808 /* Subroutine of resolve_overloaded_unification; does deduction for a single
23809 overload. Fills TARGS with any deduced arguments, or error_mark_node if
23810 different overloads deduce different arguments for a given parm.
23811 ADDR_P is true if the expression for which deduction is being
23812 performed was of the form "& fn" rather than simply "fn".
23814 Returns 1 on success. */
23816 static int
23818 tree orig_targs,
23819 tree targs,
23820 tree parm,
23821 tree arg,
23822 unification_kind_t strict,
23826 {
23828 tree tempargs;
23834 /* [temp.deduct.type] A template-argument can be deduced from a pointer
23835 to function or pointer to member function argument if the set of
23836 overloaded functions does not contain function templates and at most
23837 one of a set of overloaded functions provides a unique match.
23839 So if this is a template, just return success. */
23852 /* We don't copy orig_targs for this because if we have already deduced
23853 some template args from previous args, unify would complain when we
23854 try to deduce a template parameter for the same argument, even though
23855 there isn't really a conflict. */
23862 /* First make sure we didn't deduce anything that conflicts with
23863 explicitly specified args. */
23865 {
23872 /* Since we're unifying against ourselves, we will fill in
23873 template args used in the function parm list with our own
23874 template parms. Discard them. */
23877 {
23878 /* Check that the argument at each index of the deduced argument pack
23879 is equivalent to the corresponding explicitly specified argument.
23880 We may have deduced more arguments than were explicitly specified,
23881 and that's OK. */
23883 /* We used to assert ARGUMENT_PACK_INCOMPLETE_P (oldelt) here, but
23884 that's wrong if we deduce the same argument pack from multiple
23885 function arguments: it's only incomplete the first time. */
23898 }
23901 }
23904 {
23909 }
23912 }
23914 /* PARM is a template class (perhaps with unbound template
23915 parameters). ARG is a fully instantiated type. If ARG can be
23916 bound to PARM, return ARG, otherwise return NULL_TREE. TPARMS and
23917 TARGS are as for unify. */
23919 static tree
23922 {
23930 /* We need to make a new template argument vector for the call to
23931 unify. If we used TARGS, we'd clutter it up with the result of
23932 the attempted unification, even if this class didn't work out.
23933 We also don't want to commit ourselves to all the unifications
23934 we've already done, since unification is supposed to be done on
23935 an argument-by-argument basis. In other words, consider the
23936 following pathological case:
23938 template <int I, int J, int K>
23939 struct S {};
23941 template <int I, int J>
23942 struct S<I, J, 2> : public S<I, I, I>, S<J, J, J> {};
23944 template <int I, int J, int K>
23945 void f(S<I, J, K>, S<I, I, I>);
23947 void g() {
23948 S<0, 0, 0> s0;
23949 S<0, 1, 2> s2;
23951 f(s0, s2);
23952 }
23954 Now, by the time we consider the unification involving `s2', we
23955 already know that we must have `f<0, 0, 0>'. But, even though
23956 `S<0, 1, 2>' is derived from `S<0, 0, 0>', the code is invalid
23957 because there are two ways to unify base classes of S<0, 1, 2>
23958 with S<I, I, I>. If we kept the already deduced knowledge, we
23959 would reject the possibility I=1. */
23967 else
23974 }
23976 /* Given a template type PARM and a class type ARG, find the unique
23977 base type in ARG that is an instance of PARM. We do not examine
23978 ARG itself; only its base-classes. If there is not exactly one
23979 appropriate base class, return NULL_TREE. PARM may be the type of
23980 a partial specialization, as well as a plain template type. Used
23981 by unify. */
23983 static enum template_base_result
23986 {
23988 tree binfo;
23994 {
23995 /* The type could not be completed. */
23998 }
24000 /* Walk in inheritance graph order. The search order is not
24001 important, and this avoids multiple walks of virtual bases. */
24003 {
24008 {
24009 /* If there is more than one satisfactory baseclass, then:
24011 [temp.deduct.call]
24013 If they yield more than one possible deduced A, the type
24014 deduction fails.
24016 applies. */
24018 {
24019 /* [temp.deduct.call]/4.3: If there is a class C that is a
24020 (direct or indirect) base class of D and derived (directly or
24021 indirectly) from a class B and that would be a valid deduced
24022 A, the deduced A cannot be B or pointer to B, respectively. */
24024 /* Ignore r. */
24028 else
24029 {
24032 }
24033 }
24036 }
24037 }
24041 }
24043 /* Returns the level of DECL, which declares a template parameter. */
24045 static int
24047 {
24049 {
24059 }
24061 }
24063 /* Decide whether ARG can be unified with PARM, considering only the
24064 cv-qualifiers of each type, given STRICT as documented for unify.
24065 Returns nonzero iff the unification is OK on that basis. */
24067 static int
24069 {
24075 {
24076 /* Although a CVR qualifier is ignored when being applied to a
24077 substituted template parameter ([8.3.2]/1 for example), that
24078 does not allow us to unify "const T" with "int&" because both
24079 types are not of the form "cv-list T" [14.8.2.5 temp.deduct.type].
24080 It is ok when we're allowing additional CV qualifiers
24081 at the outer level [14.8.2.1]/3,1st bullet. */
24090 }
24101 }
24103 /* Determines the LEVEL and INDEX for the template parameter PARM. */
24104 void
24106 {
24110 {
24113 }
24114 else
24115 {
24118 }
24119 }
24121 #define RECUR_AND_CHECK_FAILURE(TP, TA, P, A, S, EP) \
24122 do { \
24123 if (unify (TP, TA, P, A, S, EP)) \
24124 return 1; \
24125 } while (0)
24127 /* Unifies the remaining arguments in PACKED_ARGS with the pack
24128 expansion at the end of PACKED_PARMS. Returns 0 if the type
24129 deduction succeeds, 1 otherwise. STRICT is the same as in
24130 fn_type_unification. CALL_ARGS_P is true iff PACKED_ARGS is actually a
24131 function call argument list. We'll need to adjust the arguments to make them
24132 types. SUBR tells us if this is from a recursive call to
24133 type_unification_real, or for comparing two template argument
24134 lists. */
24136 static int
24140 {
24141 tree parm
24147 /* Add in any args remembered from an earlier partial instantiation. */
24155 /* Determine the parameter packs we will be deducing from the
24156 pattern, and record their current deductions. */
24159 {
24163 /* Only template parameter packs can be deduced, not e.g. function
24164 parameter packs or __bases or __integer_pack. */
24168 /* Determine the index and level of this parameter pack. */
24173 /* Keep track of the parameter packs and their corresponding
24174 argument packs. */
24177 }
24179 /* Loop through all of the arguments that have not yet been
24180 unified and unify each with the pattern. */
24182 {
24183 tree parm;
24187 /* For each parameter pack, set its TMPL_ARG to either NULL_TREE
24188 or the element of its argument pack at the current index if
24189 this argument was explicitly specified. */
24191 {
24200 {
24203 }
24205 }
24207 /* If we had explicit template arguments, substitute them into the
24208 pattern before deduction. */
24210 {
24211 /* Some arguments might still be unspecified or dependent. */
24219 NULL_TREE);
24224 }
24225 else
24228 /* Unify the pattern with the current argument. */
24230 explain_p))
24233 /* For each parameter pack, collect the deduced value. */
24235 {
24241 }
24242 }
24244 /* Verify that the results of unification with the parameter packs
24245 produce results consistent with what we've seen before, and make
24246 the deduced argument packs available. */
24248 {
24255 /* By default keep the original deduced argument pack.
24256 If necessary, more specific code is going to update the
24257 resulting deduced argument later down in this function. */
24261 /* If NEW_ARGS contains any NULL_TREE entries, we didn't
24262 actually deduce anything. */
24270 {
24271 /* If we had fewer function args than explicit template args,
24272 just use the explicits. */
24277 }
24280 {
24281 tree result;
24282 /* Build the deduced *_ARGUMENT_PACK. */
24284 {
24287 }
24288 else
24293 /* Note the deduced argument packs for this parameter
24294 pack. */
24296 }
24300 {
24301 /* We only had the explicitly-provided arguments before, but
24302 now we have a complete set of arguments. */
24308 }
24309 else
24310 {
24314 /* During template argument deduction for the aggregate deduction
24315 candidate, the number of elements in a trailing parameter pack
24316 is only deduced from the number of remaining function
24317 arguments if it is not otherwise deduced. */
24320 /* FIXME This isn't set properly for partial instantiations. */
24326 /* Inconsistent unification of this parameter pack. */
24328 bad_old_arg,
24329 bad_new_arg);
24330 }
24331 }
24334 }
24336 /* Handle unification of the domain of an array. PARM_DOM and ARG_DOM are
24337 INTEGER_TYPEs representing the TYPE_DOMAIN of ARRAY_TYPEs. The other
24338 parameters and return value are as for unify. */
24340 static int
24344 {
24345 tree parm_max;
24346 tree arg_max;
24350 /* Our representation of array types uses "N - 1" as the
24351 TYPE_MAX_VALUE for an array with "N" elements, if "N" is
24352 not an integer constant. We cannot unify arbitrarily
24353 complex expressions, so we eliminate the MINUS_EXPRs
24354 here. */
24358 {
24361 }
24365 {
24366 /* The ARG_MAX may not be a simple MINUS_EXPR, if we are
24367 trying to unify the type of a variable with the type
24368 of a template parameter. For example:
24370 template <unsigned int N>
24371 void f (char (&) [N]);
24372 int g();
24373 void h(int i) {
24374 char a[g(i)];
24375 f(a);
24376 }
24378 Here, the type of the ARG will be "int [g(i)]", and
24379 may be a SAVE_EXPR, etc. */
24383 }
24385 /* If only one of the bounds used a MINUS_EXPR, compensate
24386 by adding one to the other bound. */
24389 integer_type_node,
24390 parm_max,
24391 integer_one_node);
24394 integer_type_node,
24395 arg_max,
24396 integer_one_node);
24400 }
24402 /* Returns whether T, a P or A in unify, is a type, template or expression. */
24406 static pa_kind_t
24408 {
24417 else
24419 }
24421 /* Deduce the value of template parameters. TPARMS is the (innermost)
24422 set of template parameters to a template. TARGS is the bindings
24423 for those template parameters, as determined thus far; TARGS may
24424 include template arguments for outer levels of template parameters
24425 as well. PARM is a parameter to a template function, or a
24426 subcomponent of that parameter; ARG is the corresponding argument.
24427 This function attempts to match PARM with ARG in a manner
24428 consistent with the existing assignments in TARGS. If more values
24429 are deduced, then TARGS is updated.
24431 Returns 0 if the type deduction succeeds, 1 otherwise. The
24432 parameter STRICT is a bitwise or of the following flags:
24434 UNIFY_ALLOW_NONE:
24435 Require an exact match between PARM and ARG.
24436 UNIFY_ALLOW_MORE_CV_QUAL:
24437 Allow the deduced ARG to be more cv-qualified (by qualification
24438 conversion) than ARG.
24439 UNIFY_ALLOW_LESS_CV_QUAL:
24440 Allow the deduced ARG to be less cv-qualified than ARG.
24441 UNIFY_ALLOW_DERIVED:
24442 Allow the deduced ARG to be a template base class of ARG,
24443 or a pointer to a template base class of the type pointed to by
24444 ARG.
24445 UNIFY_ALLOW_INTEGER:
24446 Allow any integral type to be deduced. See the TEMPLATE_PARM_INDEX
24447 case for more information.
24448 UNIFY_ALLOW_OUTER_LEVEL:
24449 This is the outermost level of a deduction. Used to determine validity
24450 of qualification conversions. A valid qualification conversion must
24451 have const qualified pointers leading up to the inner type which
24452 requires additional CV quals, except at the outer level, where const
24453 is not required [conv.qual]. It would be normal to set this flag in
24454 addition to setting UNIFY_ALLOW_MORE_CV_QUAL.
24455 UNIFY_ALLOW_OUTER_MORE_CV_QUAL:
24456 This is the outermost level of a deduction, and PARM can be more CV
24457 qualified at this point.
24458 UNIFY_ALLOW_OUTER_LESS_CV_QUAL:
24459 This is the outermost level of a deduction, and PARM can be less CV
24460 qualified at this point. */
24462 static int
24465 {
24467 tree targ;
24468 tree tparm;
24470 tsubst_flags_t complain = (explain_p
24471 ? tf_warning_or_error
24474 /* I don't think this will do the right thing with respect to types.
24475 But the only case I've seen it in so far has been array bounds, where
24476 signedness is the only information lost, and I think that will be
24477 okay. VIEW_CONVERT_EXPR can appear with class NTTP, thanks to
24478 finish_id_expression_1, and are also OK. */
24486 /* We can't deduce anything from this, but we might get all the
24487 template args from other function args. */
24493 /* If PARM uses template parameters, then we can't bail out here,
24494 even if ARG == PARM, since we won't record unifications for the
24495 template parameters. We might need them if we're trying to
24496 figure out which of two things is more specialized. */
24501 /* Handle init lists early, so the rest of the function can assume
24502 we're dealing with a type. */
24504 {
24505 tree elttype;
24510 /* We can only deduce from an initializer list argument if the
24511 parameter is std::initializer_list or an array; otherwise this
24512 is a non-deduced context. */
24517 else
24518 {
24520 /* Deduction is defined in terms of a single type, so just punt
24521 on the (bizarre) std::initializer_list<T...>. */
24524 }
24529 /* If ELTTYPE has no deducible template parms, skip deduction from
24531 else
24533 {
24541 {
24545 /* It should only be possible to get here for a call. */
24547 elt_strict |= maybe_adjust_types_for_deduction
24550 }
24553 explain_p);
24554 }
24558 {
24559 /* Also deduce from the length of the initializer list. */
24566 }
24568 /* If the std::initializer_list<T> deduction worked, replace the
24569 deduced A with std::initializer_list<A>. */
24571 {
24576 }
24578 }
24580 /* If parm and arg aren't the same kind of thing (template, type, or
24581 expression), fail early. */
24585 /* Immediately reject some pairs that won't unify because of
24586 cv-qualification mismatches. */
24589 /* It is the elements of the array which hold the cv quals of an array
24590 type, and the elements might be template type parms. We'll check
24591 when we recurse. */
24593 /* We check the cv-qualifiers when unifying with template type
24594 parameters below. We want to allow ARG `const T' to unify with
24595 PARM `T' for example, when computing which of two templates
24596 is more specialized, for example. */
24605 /* PMFs recurse at the same level, so don't strip this yet. */
24613 {
24617 /* In a type which contains a nested-name-specifier, template
24618 argument values cannot be deduced for template parameters used
24619 within the nested-name-specifier. */
24631 /* The PARM is not one we're trying to unify. Just check
24632 to see if it matches ARG. */
24633 {
24638 else
24640 }
24647 /* Check for mixed types and values. */
24655 {
24658 {
24659 /* First try to match ARG directly. */
24661 explain_p);
24663 {
24664 /* Otherwise, look for a suitable base of ARG, as below. */
24671 }
24672 }
24673 /* ARG must be constructed from a template class or a template
24674 template parameter. */
24679 /* Deduce arguments T, i from TT<T> or TT<i>. */
24685 /* If the template is a template template parameter, use the
24686 TEMPLATE_TEMPLATE_PARM for matching. */
24689 /* Fall through to deduce template name. */
24690 }
24694 {
24695 /* Deduce template name TT from TT, TT<>, TT<T> and TT<i>. */
24697 /* Simple cases: Value already set, does match or doesn't. */
24702 }
24703 else
24704 {
24705 /* If PARM is `const T' and ARG is only `int', we don't have
24706 a match unless we are allowing additional qualification.
24707 If ARG is `const int' and PARM is just `T' that's OK;
24708 that binds `const int' to `T'. */
24713 /* Consider the case where ARG is `const volatile int' and
24714 PARM is `const T'. Then, T should be `volatile int'. */
24715 arg = cp_build_qualified_type
24720 /* Simple cases: Value already set, does match or doesn't. */
24726 /* Make sure that ARG is not a variable-sized array. (Note
24727 that were talking about variable-sized arrays (like
24728 `int[n]'), rather than arrays of unknown size (like
24729 `int[]').) We'll get very confused by such a type since
24730 the bound of the array is not constant, and therefore
24731 not mangleable. Besides, such types are not allowed in
24732 ISO C++, so we can do as we please here. We do allow
24733 them for 'auto' deduction, since that isn't ABI-exposed. */
24737 /* Strip typedefs as in convert_template_argument. */
24739 }
24741 /* If ARG is a parameter pack or an expansion, we cannot unify
24742 against it unless PARM is also a parameter pack. */
24747 /* If the argument deduction results is a METHOD_TYPE,
24748 then there is a problem.
24749 METHOD_TYPE doesn't map to any real C++ type the result of
24750 the deduction cannot be of that type. */
24764 {
24765 /* The PARM is not one we're trying to unify. Just check
24766 to see if it matches ARG. */
24772 }
24778 {
24782 /* We're deducing from an array bound, the type doesn't matter.
24783 This conversion should match the one below. */
24789 }
24791 /* [temp.deduct.type] If, in the declaration of a function template
24792 with a non-type template-parameter, the non-type
24793 template-parameter is used in an expression in the function
24794 parameter-list and, if the corresponding template-argument is
24795 deduced, the template-argument type shall match the type of the
24796 template-parameter exactly, except that a template-argument
24797 deduced from an array bound may be of any integral type.
24798 The non-type parameter might use already deduced type parameters. */
24801 /* We don't have enough levels of args to do any substitution. This
24803 else
24804 {
24810 {
24813 LOOKUP_NORMAL,
24817 }
24818 }
24822 /* Template-parameter dependent expression. Just accept it for now.
24823 It will later be processed in convert_template_argument. */
24824 ;
24828 /* OK. Ignore top-level quals here because a class-type template
24832 /* Convert the ARG to the type of PARM; the deduced non-type
24833 template argument must exactly match the types of the
24834 corresponding parameter. This conversion should match the
24835 one above. */
24838 {
24839 /* We haven't deduced the type of this parameter yet. */
24841 /* We deduce from array bounds in try_array_deduction. */
24844 {
24845 /* Deduce it from the non-type argument. As above, ignore
24846 top-level quals here too. */
24851 /* Now check whether the type of this parameter is still
24852 dependent, and give up if so. */
24858 }
24859 else
24860 /* Try again later. */
24862 }
24863 else
24866 /* If ARG is a parameter pack or an expansion, we cannot unify
24867 against it unless PARM is also a parameter pack. */
24872 {
24875 }
24880 {
24881 /* A pointer-to-member constant can be unified only with
24882 another constant. */
24886 /* Just unify the class member. It would be useless (and possibly
24887 wrong, depending on the strict flags) to unify also
24888 PTRMEM_CST_CLASS, because we want to be sure that both parm and
24889 arg refer to the same variable, even if through different
24890 classes. For instance:
24892 struct A { int x; };
24893 struct B : A { };
24895 Unification of &A::x and &B::x must succeed. */
24898 }
24901 {
24905 /* [temp.deduct.call]
24907 A can be another pointer or pointer to member type that can
24908 be converted to the deduced A via a qualification
24909 conversion (_conv.qual_).
24911 We pass down STRICT here rather than UNIFY_ALLOW_NONE.
24912 This will allow for additional cv-qualification of the
24913 pointed-to types if appropriate. */
24916 /* The derived-to-base conversion only persists through one
24917 level of pointers. */
24922 }
24955 /* We have already checked cv-qualification at the top of the
24956 function. */
24960 /* As far as unification is concerned, this wins. Later checks
24961 will invalidate it if necessary. */
24964 /* Types INTEGER_CST and MINUS_EXPR can come from array bounds. */
24965 /* Type INTEGER_CST can come from ordinary constant template args. */
24981 {
24991 /* Check for pack expansions in the parameters. */
24993 {
24995 {
24997 /* We can unify against something with a trailing
24998 parameter pack. */
25000 else
25001 /* [temp.deduct.type]/9: If the template argument list of
25002 P contains a pack expansion that is not the last
25003 template argument, the entire template argument list
25004 is a non-deduced context. */
25006 }
25007 }
25009 /* If we don't have enough arguments to satisfy the parameters
25010 (not counting the pack expression at the end), or we have
25011 too many arguments for a parameter list that doesn't end in
25012 a pack expression, we can't unify. */
25018 /* Unify all of the parameters that precede the (optional)
25019 pack expression. */
25021 {
25026 }
25029 DEDUCE_EXACT,
25032 }
25040 {
25048 }
25053 {
25057 {
25058 /* First, we try to unify the PARM and ARG directly. */
25063 {
25064 /* Fallback to the special case allowed in
25065 [temp.deduct.call]:
25067 If P is a class, and P has the form
25068 template-id, then A can be a derived class of
25069 the deduced A. Likewise, if P is a pointer to
25070 a class of the form template-id, A can be a
25071 pointer to a derived class pointed to by the
25072 deduced A. */
25078 {
25079 /* Don't give the derived diagnostic if we're
25080 already dealing with the same template. */
25081 bool same_template
25087 }
25088 }
25089 }
25093 /* Perhaps PARM is something like S<U> and ARG is S<int>.
25094 Then, we should unify `int' and `U'. */
25096 else
25097 /* There's no chance of unification succeeding. */
25105 else
25107 }
25114 {
25117 tree a;
25123 /* CV qualifications for methods can never be deduced, they must
25124 match exactly. We need to check them explicitly here,
25125 because type_unification_real treats them as any other
25126 cv-qualified parameter. */
25128 && (!check_cv_quals_for_unify
25156 {
25166 else
25167 {
25170 /* Here "less cv-qual" means the deduced arg (i.e. parm) has
25171 /more/ noexcept, since function pointer conversions are the
25172 reverse of qualification conversions. */
25177 else
25179 }
25180 }
25182 {
25183 /* As for noexcept. */
25190 else
25192 }
25195 }
25198 /* Unify a pointer to member with a pointer to member function, which
25199 deduces the type of the member as a function type. */
25201 {
25202 /* Check top-level cv qualifiers */
25210 /* Determine the type of the function we are unifying against. */
25214 }
25225 /* CONST_DECL should already have been folded to its DECL_INITIAL. */
25231 /* Matched cases are handled by the ARG == PARM test above. */
25235 /* We might get a variable as a non-type template argument in parm if the
25236 corresponding parameter is type-dependent. Make any necessary
25237 adjustments based on whether arg is a reference. */
25241 {
25246 }
25247 /* Now use the normal expression code to check whether they match. */
25258 /* Cannot deduce anything from TYPEOF_TYPE, DECLTYPE_TYPE,
25259 or TRAIT_TYPE nodes. */
25263 /* Unification fails if we hit an error node. */
25268 {
25278 }
25279 /* FALLTHRU */
25282 /* An unresolved overload is a nondeduced context. */
25288 expr:
25289 /* We must be looking at an expression. This can happen with
25290 something like:
25292 template <int I>
25293 void foo(S<I>, S<I + 2>);
25295 or
25297 template<typename T>
25298 void foo(A<T, T{}>);
25300 This is a "non-deduced context":
25302 [deduct.type]
25304 The non-deduced contexts are:
25306 --A non-type template argument or an array bound in which
25307 a subexpression references a template parameter.
25309 In these cases, we assume deduction succeeded, but don't
25310 actually infer any unifications. */
25315 else
25317 }
25318 }
25319 #undef RECUR_AND_CHECK_FAILURE
25320 \f
25321 /* Note that DECL can be defined in this translation unit, if
25322 required. */
25324 static void
25326 {
25327 tree clone;
25331 }
25333 /* Called if RESULT is explicitly instantiated, or is a member of an
25334 explicitly instantiated class. */
25336 void
25338 {
25341 /* If this entity has already been written out, it's too late to
25342 make any modifications. */
25346 /* consteval functions are never emitted. */
25351 /* For anonymous namespace we don't need to do anything. */
25353 {
25356 }
25359 /* The TREE_PUBLIC flag for function declarations will have been
25360 set correctly by tsubst. */
25364 {
25367 }
25368 else
25369 {
25372 /* Always make artificials weak. */
25375 /* For WIN32 we also want to put explicit instantiations in
25376 linkonce sections. */
25381 /* If the function has already been instantiated, clear DECL_EXTERNAL,
25382 since start_preparsed_function wouldn't have if we had an earlier
25383 extern explicit instantiation. */
25385 }
25387 /* If EXTERN_P, then this function will not be emitted -- unless
25388 followed by an explicit instantiation, at which point its linkage
25389 will be adjusted. If !EXTERN_P, then this function will be
25390 emitted here. In neither circumstance do we want
25391 import_export_decl to adjust the linkage. */
25393 }
25395 /* Subroutine of more_specialized_fn: check whether TARGS is missing any
25396 important template arguments. If any are missing, we check whether
25397 they're important by using error_mark_node for substituting into any
25398 args that were used for partial ordering (the ones between ARGS and END)
25399 and seeing if it bubbles up. */
25401 static bool
25403 {
25407 {
25410 }
25412 {
25416 }
25418 }
25420 /* Given two function templates PAT1 and PAT2, return:
25422 1 if PAT1 is more specialized than PAT2 as described in [temp.func.order].
25423 -1 if PAT2 is more specialized than PAT1.
25424 0 if neither is more specialized.
25426 LEN indicates the number of parameters we should consider
25427 (defaulted parameters should not be considered).
25429 The 1998 std underspecified function template partial ordering, and
25430 DR214 addresses the issue. We take pairs of arguments, one from
25431 each of the templates, and deduce them against each other. One of
25432 the templates will be more specialized if all the *other*
25433 template's arguments deduce against its arguments and at least one
25434 of its arguments *does* *not* deduce against the other template's
25435 corresponding argument. Deduction is done as for class templates.
25436 The arguments used in deduction have reference and top level cv
25437 qualifiers removed. Iff both arguments were originally reference
25438 types *and* deduction succeeds in both directions, an lvalue reference
25439 wins against an rvalue reference and otherwise the template
25440 with the more cv-qualified argument wins for that pairing (if
25441 neither is more cv-qualified, they both are equal). Unlike regular
25442 deduction, after all the arguments have been deduced in this way,
25443 we do *not* verify the deduced template argument values can be
25444 substituted into non-deduced contexts.
25446 The logic can be a bit confusing here, because we look at deduce1 and
25447 targs1 to see if pat2 is at least as specialized, and vice versa; if we
25448 can find template arguments for pat1 to make arg1 look like arg2, that
25449 means that arg2 is at least as specialized as arg1. */
25451 int
25453 {
25466 /* C++17 [temp.func.order]/3 (CWG532)
25468 If only one of the function templates M is a non-static member of some
25469 class A, M is considered to have a new first parameter inserted in its
25470 function parameter list. Given cv as the cv-qualifiers of M (if any), the
25471 new parameter is of type "rvalue reference to cv A" if the optional
25472 ref-qualifier of M is && or if M has no ref-qualifier and the first
25473 parameter of the other template has rvalue reference type. Otherwise, the
25474 new parameter is of type "lvalue reference to cv A". */
25477 {
25478 /* Note C++20 DR2445 extended the above to static member functions, but
25479 I think think the old G++ behavior of just skipping the object
25480 parameter when comparing to a static member function was better, so
25481 let's stick with that for now. This is CWG2834. --jason 2023-12 */
25483 {
25486 }
25489 }
25492 {
25493 /* Note DR2445 also (IMO wrongly) removed the "only one" above, which
25494 would break e.g. cpp1y/lambda-generic-variadic5.C. */
25495 len--;
25498 }
25501 {
25502 /* The other is a non-member or explicit object member function;
25503 rewrite the implicit object parameter to a reference. */
25512 {
25518 }
25521 }
25523 /* If only one is a conversion operator, they are unordered. */
25527 /* Consider the return type for a conversion function */
25529 {
25532 len++;
25533 }
25535 processing_template_decl++;
25541 /* Stop when an ellipsis is seen. */
25543 {
25554 {
25555 /* When both arguments are pack expansions, we need only
25556 unify the patterns themselves. */
25560 /* This is the last comparison we need to do. */
25562 }
25565 {
25569 }
25572 {
25576 }
25582 {
25588 /* Setup the parameter vector, which contains only ARG1. */
25591 /* Setup the argument vector, which contains the remaining
25592 arguments. */
25601 /* We cannot deduce in the other direction, because ARG1 is
25602 a pack expansion but ARG2 is not. */
25604 }
25606 {
25612 /* Setup the parameter vector, which contains only ARG1. */
25615 /* Setup the argument vector, which contains the remaining
25616 arguments. */
25625 /* We cannot deduce in the other direction, because ARG2 is
25626 a pack expansion but ARG1 is not.*/
25628 }
25630 else
25631 {
25632 /* The normal case, where neither argument is a pack
25633 expansion. */
25640 }
25642 /* If we couldn't deduce arguments for tparms1 to make arg1 match
25643 arg2, then arg2 is not as specialized as arg1. */
25649 /* "If, for a given type, deduction succeeds in both directions
25650 (i.e., the types are identical after the transformations above)
25651 and both P and A were reference types (before being replaced with
25652 the type referred to above):
25653 - if the type from the argument template was an lvalue reference and
25654 the type from the parameter template was not, the argument type is
25655 considered to be more specialized than the other; otherwise,
25656 - if the type from the argument template is more cv-qualified
25657 than the type from the parameter template (as described above),
25658 the argument type is considered to be more specialized than the other;
25659 otherwise,
25660 - neither type is more specialized than the other." */
25663 {
25665 {
25668 else
25670 }
25672 {
25677 }
25678 }
25681 /* We've failed to deduce something in either direction.
25682 These must be unordered. */
25687 /* We have already processed all of the arguments in our
25688 handing of the pack expansion type. */
25693 }
25695 /* "In most cases, all template parameters must have values in order for
25696 deduction to succeed, but for partial ordering purposes a template
25697 parameter may remain without a value provided it is not used in the
25698 types being used for partial ordering."
25700 Thus, if we are missing any of the targs1 we need to substitute into
25701 origs1, then pat2 is not as specialized as pat1. This can happen when
25702 there is a nondeduced context. */
25708 processing_template_decl--;
25710 /* If both deductions succeed, the partial ordering selects the more
25711 constrained template. */
25712 /* P2113: If the corresponding template-parameters of the
25713 template-parameter-lists are not equivalent ([temp.over.link]) or if
25714 the function parameters that positionally correspond between the two
25715 templates are not of the same type, neither template is more
25716 specialized than the other. */
25721 {
25727 }
25729 /* All things being equal, if the next argument is a pack expansion
25730 for one function but not for the other, prefer the
25731 non-variadic function. FIXME this is bogus; see c++/41958. */
25735 {
25738 }
25744 else
25746 }
25748 /* Determine which of two partial specializations of TMPL is more
25749 specialized.
25751 PAT1 is a TREE_LIST whose TREE_VALUE is the TEMPLATE_DECL corresponding
25752 to the first partial specialization. The TREE_PURPOSE is the
25753 innermost set of template parameters for the partial
25754 specialization. PAT2 is similar, but for the second template.
25756 Return 1 if the first partial specialization is more specialized;
25757 -1 if the second is more specialized; 0 if neither is more
25758 specialized.
25760 See [temp.class.order] for information about determining which of
25761 two templates is more specialized. */
25763 static int
25765 {
25766 tree targs;
25775 /* Just like what happens for functions, if we are ordering between
25776 different template specializations, we may encounter dependent
25777 types in the arguments, and we need our dependency check functions
25778 to behave correctly. */
25782 {
25785 }
25789 {
25792 }
25795 /* If both deductions succeed, the partial ordering selects the more
25796 constrained template. */
25800 /* In the case of a tie where at least one of the templates
25801 has a parameter pack at the end, the template with the most
25802 non-packed parameters wins. */
25804 && any_deductions
25807 {
25813 /* We don't count the pack expansion at the end. */
25823 }
25826 }
25828 /* Return the template arguments that will produce the function signature
25829 DECL from the function template FN, with the explicit template
25830 arguments EXPLICIT_ARGS. If CHECK_RETTYPE is true, the return type must
25831 also match. Return NULL_TREE if no satisfactory arguments could be
25832 found. */
25834 static tree
25836 {
25840 tree decl_arg_types;
25843 tree arg;
25847 /* Never do unification on the 'this' parameter. */
25869 }
25871 /* Return the innermost template arguments that, when applied to a partial
25872 specialization SPEC_TMPL of TMPL, yield the ARGS.
25874 For example, suppose we have:
25876 template <class T, class U> struct S {};
25877 template <class T> struct S<T*, int> {};
25879 Then, suppose we want to get `S<double*, int>'. SPEC_TMPL will be the
25880 partial specialization and the ARGS will be {double*, int}. The resulting
25881 vector will be {double}, indicating that `T' is bound to `double'. */
25883 static tree
25885 {
25887 tree spec_args
25890 tree deduced_args;
25891 tree innermost_deduced_args;
25895 {
25899 innermost_deduced_args);
25900 }
25901 else
25905 again:
25914 {
25916 {
25922 }
25924 }
25927 {
25930 }
25932 /* Verify that nondeduced template arguments agree with the type
25933 obtained from argument deduction.
25935 For example:
25937 struct A { typedef int X; };
25938 template <class T, class U> struct C {};
25939 template <class T> struct C<T, typename T::X> {};
25941 Then with the instantiation `C<A, int>', we can deduce that
25942 `T' is `A' but unify () does not check whether `typename T::X'
25943 is `int'. */
25954 /* We only need to check the innermost arguments; the other
25955 arguments will always agree. */
25960 /* Now that we have bindings for all of the template arguments,
25961 ensure that the arguments deduced for the template template
25962 parameters have compatible template parameter lists. See the use
25963 of template_template_parm_bindings_ok_p in fn_type_unification
25964 for more information. */
25969 }
25971 // Compare two function templates T1 and T2 by deducing bindings
25972 // from one against the other. If both deductions succeed, compare
25973 // constraints to see which is more constrained.
25974 static int
25976 {
25981 {
25984 }
25987 {
25990 }
25992 // If both deductions succeed, then one may be more constrained.
25997 }
25999 /* TEMPLATES is a TREE_LIST. Each TREE_VALUE is a TEMPLATE_DECL.
26000 Return the TREE_LIST node with the most specialized template, if
26001 any. If there is no most specialized template, the error_mark_node
26002 is returned.
26004 Note that this function does not look at, or modify, the
26005 TREE_PURPOSE or TREE_TYPE of any of the nodes. Since the node
26006 returned is one of the elements of INSTANTIATIONS, callers may
26007 store information in the TREE_PURPOSE or TREE_TYPE of the nodes,
26008 and retrieve it from the value returned. */
26010 tree
26012 {
26019 {
26025 {
26026 /* Equally specialized, move to next function. If there
26027 is no next function, nothing's most specialized. */
26032 }
26033 }
26036 /* Now verify that champ is better than everything earlier in the
26037 instantiation list. */
26040 {
26043 }
26044 }
26046 processing_template_decl--;
26052 }
26054 /* If DECL is a specialization of some template, return the most
26055 general such template. Otherwise, returns NULL_TREE.
26057 For example, given:
26059 template <class T> struct S { template <class U> void f(U); };
26061 if TMPL is `template <class U> void S<int>::f(U)' this will return
26062 the full template. This function will not trace past partial
26063 specializations, however. For example, given in addition:
26065 template <class T> struct S<T*> { template <class U> void f(U); };
26067 if TMPL is `template <class U> void S<int*>::f(U)' this will return
26068 `template <class T> template <class U> S<T*>::f(U)'. */
26070 tree
26072 {
26074 {
26077 /* The TI_TEMPLATE can be an IDENTIFIER_NODE for a
26078 template friend, or a FIELD_DECL for a capture pack. */
26081 }
26086 /* Look for more and more general templates. */
26088 {
26089 /* The DECL_TI_TEMPLATE can be an IDENTIFIER_NODE in some cases.
26090 (See cp-tree.h for details.) */
26099 /* Stop if we run into an explicitly specialized class template. */
26106 }
26109 }
26111 /* Return the most specialized of the template partial specializations
26112 which can produce TARGET, a specialization of some class or variable
26113 template. The value returned is a TEMPLATE_INFO; the TI_TEMPLATE is a
26114 TEMPLATE_DECL node corresponding to the partial specialization, while
26115 the TI_ARGS is the set of template arguments that must be substituted
26116 into the template pattern in order to generate TARGET. The result is
26117 cached in the TI_PARTIAL_INFO of the corresponding TEMPLATE_INFO unless
26118 RECHECKING is true.
26120 If the choice of partial specialization is ambiguous, a diagnostic
26121 is issued, and the error_mark_node is returned. If there are no
26122 partial specializations matching TARGET, then NULL_TREE is
26123 returned, indicating that the primary template should be used. */
26125 tree
26128 {
26132 {
26137 }
26139 {
26143 }
26145 {
26150 }
26151 else
26158 && tinfo
26165 /* There are no partial specializations of this template. */
26171 /* For determining which partial specialization to use, only the
26172 innermost args are interesting. */
26175 {
26178 }
26180 /* The caller hasn't called push_to_top_level yet, but we need
26181 get_partial_spec_bindings to be done in non-template context so that we'll
26182 fully resolve everything. */
26183 processing_template_decl_sentinel ptds;
26187 {
26190 tree spec_tmpl;
26192 {
26193 /* Substitute in the template args from the enclosing class. */
26199 }
26200 else
26205 {
26209 /* Keep the candidate only if its constraints are satisfied. */
26212 }
26213 }
26221 {
26224 ;
26225 else
26226 {
26228 {
26231 {
26234 }
26235 }
26237 }
26238 }
26242 {
26245 {
26248 }
26249 }
26252 {
26259 else
26263 {
26268 }
26271 }
26277 }
26279 /* Explicitly instantiate DECL. */
26281 void
26283 {
26288 /* An error occurred, for which grokdeclarator has already issued
26289 an appropriate message. */
26292 {
26295 }
26297 {
26300 else
26303 }
26309 {
26310 /* There is an asymmetry here in the way VAR_DECLs and
26311 FUNCTION_DECLs are handled by grokdeclarator. In the case of
26312 the latter, the DECL we get back will be marked as a
26313 template instantiation, and the appropriate
26314 DECL_TEMPLATE_INFO will be set up. This does not happen for
26315 VAR_DECLs so we do the lookup here. Probably, grokdeclarator
26316 should handle VAR_DECLs as it currently handles
26317 FUNCTION_DECLs. */
26319 {
26322 }
26325 {
26328 }
26330 {
26335 }
26336 }
26338 {
26341 }
26342 else
26345 /* Check for various error cases. Note that if the explicit
26346 instantiation is valid the RESULT will currently be marked as an
26347 *implicit* instantiation; DECL_EXPLICIT_INSTANTIATION is not set
26348 until we get here. */
26351 {
26352 /* DR 259 [temp.spec].
26354 Both an explicit instantiation and a declaration of an explicit
26355 specialization shall not appear in a program unless the explicit
26356 instantiation follows a declaration of the explicit specialization.
26358 For a given set of template parameters, if an explicit
26359 instantiation of a template appears after a declaration of an
26360 explicit specialization for that template, the explicit
26361 instantiation has no effect. */
26363 }
26365 {
26366 /* [temp.spec]
26368 No program shall explicitly instantiate any template more
26369 than once.
26371 We check DECL_NOT_REALLY_EXTERN so as not to complain when
26372 the first instantiation was `extern' and the second is not,
26373 and EXTERN_P for the opposite case. */
26376 /* If an "extern" explicit instantiation follows an ordinary
26377 explicit instantiation, the template is instantiated. */
26380 }
26382 {
26385 }
26387 {
26390 }
26393 ;
26395 {
26398 "ISO C++ 1998 forbids the use of %<extern%> on explicit "
26401 }
26402 else
26410 }
26412 static void
26414 {
26420 {
26423 }
26424 }
26426 /* Perform an explicit instantiation of template class T. STORAGE, if
26427 non-null, is the RID for extern, inline or static. COMPLAIN is
26428 nonzero if this is called from the parser, zero if called recursively,
26429 since the standard is unclear (as detailed below). */
26431 void
26433 {
26435 {
26439 else
26442 }
26447 {
26450 t);
26452 }
26454 /* At most one of these will be true. */
26460 {
26462 {
26465 "ISO C++ 1998 forbids the use of %<extern%> on "
26467 }
26468 else
26470 "ISO C++ forbids the use of %qE"
26479 else
26481 storage);
26482 }
26485 /* DR 259 [temp.spec].
26487 Both an explicit instantiation and a declaration of an explicit
26488 specialization shall not appear in a program unless the
26489 explicit instantiation follows a declaration of the explicit
26490 specialization.
26492 For a given set of template parameters, if an explicit
26493 instantiation of a template appears after a declaration of an
26494 explicit specialization for that template, the explicit
26495 instantiation has no effect. */
26499 {
26500 /* We've already instantiated the template. */
26502 /* [temp.spec]
26504 No program shall explicitly instantiate any template more
26505 than once.
26507 If EXTERN_P then this is ok. */
26513 }
26521 /* In contrast to implicit instantiation, where only the
26522 declarations, and not the definitions, of members are
26523 instantiated, we have here:
26525 [temp.explicit]
26527 An explicit instantiation that names a class template
26528 specialization is also an explicit instantiation of the same
26529 kind (declaration or definition) of each of its members (not
26530 including members inherited from base classes and members
26531 that are templates) that has not been previously explicitly
26532 specialized in the translation unit containing the explicit
26533 instantiation, provided that the associated constraints, if
26534 any, of that member are satisfied by the template arguments
26535 of the explicit instantiation. */
26539 && !static_p
26543 {
26548 }
26550 {
26556 }
26557 }
26559 /* Given a function DECL, which is a specialization of TMPL, modify
26560 DECL to be a re-instantiation of TMPL with the same template
26561 arguments. TMPL should be the template into which tsubst'ing
26562 should occur for DECL, not the most general template.
26564 One reason for doing this is a scenario like this:
26566 template <class T>
26567 void f(const T&, int i);
26569 void g() { f(3, 7); }
26571 template <class T>
26572 void f(const T& t, const int i) { }
26574 Note that when the template is first instantiated, with
26575 instantiate_template, the resulting DECL will have no name for the
26576 first parameter, and the wrong type for the second. So, when we go
26577 to instantiate the DECL, we regenerate it. */
26579 static void
26581 {
26582 /* The arguments used to instantiate DECL, from the most general
26583 template. */
26586 /* Make sure that we can see identifiers, and compute access correctly. */
26590 {
26591 tree specs;
26595 /* Don't bother with this for unique friends that can't be redeclared and
26596 might change type if regenerated (PR69836). */
26600 /* Use the source location of the definition. */
26608 /* Instantiate a dynamic exception-specification. noexcept will be
26609 handled below. */
26612 {
26618 specs);
26619 }
26621 /* Merge parameter declarations. */
26625 {
26632 }
26635 {
26636 /* If we're regenerating a specialization, the contracts will have
26637 been copied from the most general template. Replace those with
26638 the ones from the actual specialization. */
26641 {
26644 }
26647 }
26649 /* Merge additional specifiers from the CODE_PATTERN. */
26655 }
26657 {
26666 }
26667 else
26670 done:
26672 }
26674 /* Return the TEMPLATE_DECL into which DECL_TI_ARGS(DECL) should be
26675 substituted to get DECL. */
26677 tree
26679 {
26682 /* Set TMPL to the template whose DECL_TEMPLATE_RESULT is the pattern
26683 for the instantiation. This is not always the most general
26684 template. Consider, for example:
26686 template <class T>
26687 struct S { template <class U> void f();
26688 template <> void f<int>(); };
26690 and an instantiation of S<double>::f<int>. We want TD to be the
26691 specialization S<T>::f<int>, not the more general S<T>::f<U>. */
26693 more general template. */
26695 /* We must also deal with friend templates. Given:
26697 template <class T> struct S {
26698 template <class U> friend void f() {};
26699 };
26701 S<int>::f<U> say, is not an instantiation of S<T>::f<U>,
26702 so far as the language is concerned, but that's still
26703 where we get the pattern for the instantiation from. On
26704 other hand, if the definition comes outside the class, say:
26706 template <class T> struct S {
26707 template <class U> friend void f();
26708 };
26709 template <class U> friend void f() {}
26711 we don't need to look any further. That's what the check for
26712 DECL_INITIAL is for. */
26716 {
26717 /* The present template, TD, should not be a definition. If it
26718 were a definition, we should be using it! Note that we
26719 cannot restructure the loop to just keep going until we find
26720 a template with a definition, since that might go too far if
26721 a specialization was declared, but not defined. */
26723 /* Fetch the more general template. */
26725 }
26728 }
26730 /* Returns true if we need to instantiate this template instance even if we
26731 know we aren't going to emit it. */
26733 bool
26735 {
26736 /* We always instantiate inline functions so that we can inline them. An
26737 explicit instantiation declaration prohibits implicit instantiation of
26738 non-inline functions. With high levels of optimization, we would
26739 normally inline non-inline functions -- but we're not allowed to do
26740 that for "extern template" functions. Therefore, we check
26741 DECL_DECLARED_INLINE_P, rather than possibly_inlined_p. */
26745 /* And we need to instantiate static data members so that
26746 their initializers are available in integral constant
26747 expressions. */
26750 }
26752 /* If FN has a noexcept-specifier that hasn't been instantiated yet,
26753 instantiate it now, modifying TREE_TYPE (fn). Returns false on
26754 error, true otherwise. */
26756 bool
26758 {
26762 /* Don't instantiate a noexcept-specification from template context. */
26772 {
26774 /* We're in start_preparsed_function, keep going. */
26781 }
26792 /* For a member friend template we can get a TEMPLATE_DECL. Let's use
26793 its FUNCTION_DECL for the rest of this function -- push_access_scope
26794 doesn't accept TEMPLATE_DECLs. */
26796 {
26799 }
26802 {
26807 }
26809 {
26813 {
26816 /* This might have failed because of an unparsed DMI, so
26817 let's try again later. */
26819 }
26821 {
26822 /* If hash_set::add returns true, the element was already there. */
26827 fn);
26829 }
26831 {
26839 {
26840 /* If needed, set current_class_ptr for the benefit of
26841 tsubst_copy/PARM_DECL. */
26846 }
26848 /* If this function is represented by a TEMPLATE_DECL, then
26849 the deferred noexcept-specification might still contain
26850 dependent types, even after substitution. And we need the
26851 dependency check functions to work in build_noexcept_spec. */
26855 /* Do deferred instantiation of the noexcept-specifier. */
26860 /* Build up the noexcept-specification. */
26870 }
26871 else
26876 }
26879 {
26880 /* This failed with a hard error, so let's go with false. */
26883 }
26890 }
26892 /* We're starting to process the function INST, an instantiation of PATTERN;
26893 add their parameters to local_specializations. */
26895 void
26897 {
26901 {
26905 }
26907 {
26909 {
26912 }
26913 else
26914 {
26915 /* Register the (value) argument pack as a specialization of
26916 TMPL_PARM, then move on. */
26919 }
26920 }
26922 }
26924 /* Instantiate the body of D using PATTERN with ARGS. We have
26925 already determined PATTERN is the correct template to use.
26926 NESTED_P is true if this is a nested function, in which case
26927 PATTERN will be a FUNCTION_DECL not a TEMPLATE_DECL. */
26929 static void
26931 {
26936 {
26939 }
26940 else
26941 /* Only OMP reductions are nested. */
26953 {
26954 /* The variable might be a lambda's extra scope, and that
26955 lambda's visibility depends on D's. */
26958 }
26960 /* Mark D as instantiated so that recursive calls to
26961 instantiate_decl do not try to instantiate it again. */
26965 /* Regenerate the declaration in case the template has been modified
26966 by a subsequent redeclaration. */
26969 /* We already set the file and line above. Reset them now in case
26970 they changed as a result of calling regenerate_decl_from_template. */
26974 {
26975 /* Clear out DECL_RTL; whatever was there before may not be right
26976 since we've reset the type of the declaration. */
26980 /* The initializer is placed in DECL_INITIAL by
26981 regenerate_decl_from_template so we don't need to
26982 push/pop_access_scope again here. Pull it out so that
26983 cp_finish_decl can process it. */
26989 /* Clear DECL_EXTERNAL so that cp_finish_decl will process the
26990 initializer. That function will defer actual emission until
26991 we have a chance to determine linkage. */
26994 /* Enter the scope of D so that access-checking works correctly. */
27004 }
27008 {
27009 /* Set up the list of local specializations. */
27013 /* Set up context. */
27016 else
27017 {
27021 }
27023 /* Create substitution entries for the parameters. */
27026 /* Substitute into the body of the function. */
27030 else
27031 {
27035 /* Set the current input_location to the end of the function
27036 so that finish_function knows where we are. */
27037 input_location
27040 /* Remember if we saw an infinite loop in the template. */
27041 current_function_infinite_loop
27043 }
27045 /* Finish the function. */
27048 else
27049 {
27052 }
27056 }
27058 /* We're not deferring instantiation any more. */
27066 }
27068 /* Produce the definition of D, a _DECL generated from a template. If
27069 DEFER_OK is true, then we don't have to actually do the
27070 instantiation now; we just have to do it sometime. Normally it is
27071 an error if this is an explicit instantiation but D is undefined.
27072 EXPL_INST_CLASS_MEM_P is true iff D is a member of an explicitly
27073 instantiated class template. */
27075 tree
27077 {
27079 tree gen_args;
27080 tree args;
27081 tree td;
27082 tree code_pattern;
27083 tree spec;
27084 tree gen_tmpl;
27090 /* This function should only be used to instantiate templates for
27091 functions and static member variables. */
27094 /* A concept is never instantiated. */
27100 /* We may have a pending instantiation of D itself. */
27103 /* Variables are never deferred; if instantiation is required, they
27104 are instantiated right away. That allows for better code in the
27105 case that an expression refers to the value of the variable --
27106 if the variable has a constant value the referring expression can
27107 take advantage of that fact. */
27111 /* Don't instantiate cloned functions. Instead, instantiate the
27112 functions they cloned. */
27121 /* D has already been instantiated or explicitly specialized, so
27122 there's nothing for us to do here.
27124 It might seem reasonable to check whether or not D is an explicit
27125 instantiation, and, if so, stop here. But when an explicit
27126 instantiation is deferred until the end of the compilation,
27127 DECL_EXPLICIT_INSTANTIATION is set, even though we still need to do
27128 the instantiation. */
27131 /* Check to see whether we know that this template will be
27132 instantiated in some other file, as with "extern template"
27133 extension. */
27136 /* In general, we do not instantiate such templates. */
27143 /* We should already have the extra args. */
27147 /* And what's in the hash table should match D. */
27149 == d
27152 /* This needs to happen before any tsubsting. */
27158 /* Set TD to the template whose DECL_TEMPLATE_RESULT is the pattern
27159 for the instantiation. */
27164 {
27165 /* Look up an explicit specialization, if any. */
27168 {
27171 }
27172 }
27176 /* We should never be trying to instantiate a member of a class
27177 template or partial specialization. */
27182 /* In the case of a friend template whose definition is provided
27183 outside the class, we may have too many arguments. Drop the
27184 ones we don't need. The same is true for specializations. */
27185 args = get_innermost_template_args
27189 {
27195 }
27196 else
27197 {
27201 else
27203 }
27205 /* We may be in the middle of deferred access check. Disable it now. */
27208 /* Unless an explicit instantiation directive has already determined
27209 the linkage of D, remember that a definition is available for
27210 this entity. */
27220 /* If D is a member of an explicitly instantiated class template,
27221 and no definition is available, treat it like an implicit
27222 instantiation. */
27225 {
27226 /* Leave linkage flags alone on instantiations with anonymous
27227 visibility. */
27229 {
27232 }
27234 }
27236 /* Defer all other templates, unless we have been explicitly
27237 forbidden from doing so. */
27239 template. */
27240 ! pattern_defined
27241 /* If it's OK to postpone instantiation, do so. */
27242 || defer_ok
27243 /* If this is a static data member that will be defined
27244 elsewhere, we don't want to instantiate the entire data
27245 member, but we do want to instantiate the initializer so that
27246 we can substitute that elsewhere. */
27248 /* Handle here a deleted function too, avoid generating
27249 its body (c++/61080). */
27251 {
27252 /* The definition of the static data member is now required so
27253 we must substitute the initializer. */
27257 {
27258 tree ns;
27259 tree init;
27268 args,
27270 /* If instantiating the initializer involved instantiating this
27271 again, don't call cp_finish_decl twice. */
27273 {
27274 /* Make sure the initializer is still constant, in case of
27275 circular dependency (template/instantiate6.C). */
27276 const_init
27280 }
27284 }
27286 /* We restore the source position here because it's used by
27287 add_pending_template. */
27293 /* [temp.explicit]
27295 The definition of a non-exported function template, a
27296 non-exported member function template, or a non-exported
27297 member function or static data member of a class template
27298 shall be present in every translation unit in which it is
27299 explicitly instantiated. */
27303 /* If we're in unevaluated context, we just wanted to get the
27304 constant value; this isn't an odr use, so don't queue
27305 a full instantiation. */
27307 /* ??? Historically, we have instantiated inline functions, even
27308 when marked as "extern template". */
27311 }
27312 else
27313 {
27318 }
27325 }
27327 /* Run through the list of templates that we wish we could
27328 instantiate, and instantiate any we can. RETRIES is the
27329 number of times we retry pending template instantiation. */
27331 void
27333 {
27337 /* Instantiating templates may trigger vtable generation. This in turn
27338 may require further template instantiations. We place a limit here
27339 to avoid infinite loop. */
27341 {
27345 "template instantiation depth exceeds maximum of %d"
27346 " instantiating %q+D, possibly from virtual table generation"
27350 /* Pretend that we defined it. */
27353 }
27355 do
27356 {
27361 {
27366 {
27368 {
27383 }
27386 }
27387 else
27388 {
27391 {
27392 instantiation
27398 }
27402 }
27405 {
27406 /* If INSTANTIATION has been instantiated, then we don't
27407 need to consider it again in the future. */
27412 }
27413 else
27414 {
27417 }
27420 }
27422 }
27426 }
27428 /* Substitute ARGVEC into T, which is a list of initializers for
27429 either base class or a non-static data member. The TREE_PURPOSEs
27430 are DECLs, and the TREE_VALUEs are the initializer values. Used by
27431 instantiate_decl. */
27433 static tree
27435 {
27440 {
27441 tree decl;
27442 tree init;
27448 {
27449 tree expr;
27450 tree arg;
27452 /* Expand the base class expansion type into separate base
27453 classes. */
27455 tf_warning_or_error,
27456 NULL_TREE);
27460 /* We'll be building separate TREE_LISTs of arguments for
27461 each base. */
27467 /* Build a dummy EXPR_PACK_EXPANSION that will be used to
27468 expand each argument in the TREE_VALUE of t. */
27475 /* VOID_TYPE_NODE is used to indicate
27476 value-initialization. */
27477 {
27480 }
27481 else
27482 {
27483 /* Substitute parameter packs into each argument in the
27484 TREE_LIST. */
27487 {
27488 tree expanded_exprs;
27490 /* Expand the argument. */
27491 tree value;
27494 else
27495 {
27498 }
27499 expanded_exprs
27501 tf_warning_or_error,
27502 NULL_TREE);
27506 /* Prepend each of the expanded expressions to the
27507 corresponding TREE_LIST in EXPANDED_ARGUMENTS. */
27515 else
27520 }
27523 /* Reverse all of the TREE_LISTs in EXPANDED_ARGUMENTS,
27524 since we built them backwards. */
27526 {
27529 }
27530 }
27531 }
27534 {
27536 {
27540 }
27541 else
27542 {
27543 tree tmp;
27547 else
27561 /* If we had an initializer but it instantiated to nothing,
27562 value-initialize the object. This will only occur when
27563 the initializer was a pack expansion where the parameter
27564 packs used in that expansion were of length zero. */
27567 }
27571 {
27573 decl);
27575 }
27576 /* Look for a target constructor. */
27580 {
27583 {
27587 }
27589 }
27592 {
27594 /* Carry over the dummy TREE_TYPE node containing the source
27595 location. */
27599 }
27600 }
27601 }
27603 }
27605 /* Instantiate an enumerated type. TAG is the template type, NEWTAG
27606 is the instantiation (which should have been created with
27607 start_enum) and ARGS are the template arguments to use. */
27609 static void
27611 {
27612 tree e;
27618 {
27619 tree value;
27622 /* Note that in a template enum, the TREE_VALUE is the
27623 CONST_DECL, not the corresponding INTEGER_CST. */
27627 /* Give this enumeration constant the correct access. */
27630 /* Actually build the enumerator itself. Here we're assuming that
27631 enumerators can't have dependent attributes. */
27635 /* Attribute deprecated without an argument isn't sticky: it'll
27636 melt into a tree flag, so we need to propagate the flag here,
27637 since we just created a new enumerator. */
27640 }
27652 }
27654 /* DECL is a FUNCTION_DECL that is a template specialization. Return
27655 its type -- but without substituting the innermost set of template
27656 arguments. So, innermost set of template parameters will appear in
27657 the type. */
27659 tree
27661 {
27662 /* For a function, DECL_TI_TEMPLATE is partially instantiated. */
27664 }
27666 /* Return truthvalue if we're processing a template different from
27667 the last one involved in diagnostics. */
27668 bool
27670 {
27672 }
27674 /* Remember current template involved in diagnostics. */
27675 void
27677 {
27679 }
27683 {
27685 }
27687 /* Return TRUE if current_function_decl is being instantiated, false
27688 otherwise. */
27690 bool
27692 {
27696 }
27698 /* [temp.param] Check that template non-type parm TYPE is of an allowable
27699 type. Return false for ok, true for disallowed. Issue error and
27700 inform messages under control of COMPLAIN. */
27702 static bool
27704 {
27715 {
27717 {
27722 }
27724 }
27729 /* Fall through; before C++11 alias templates, a bound ttp
27732 /* Any other wildcard type not already handled above is allowed. */
27739 {
27747 {
27748 auto_diagnostic_group d;
27752 }
27754 }
27756 {
27761 }
27764 {
27767 else
27769 type);
27770 }
27772 }
27774 /* Returns true iff the noexcept-specifier for TYPE is value-dependent. */
27776 static bool
27778 {
27781 /* Treat DEFERRED_NOEXCEPT as non-dependent, since it doesn't
27782 affect overload resolution and treating it as dependent breaks
27783 things. Same for an unparsed noexcept expression. */
27790 }
27792 /* Returns TRUE if TYPE is dependent, in the sense of [temp.dep.type].
27793 Assumes that TYPE really is a type, and not the ERROR_MARK_NODE.*/
27795 static bool
27797 {
27798 tree scope;
27800 /* [temp.dep.type]
27802 A type is dependent if it is:
27804 -- a template parameter. Template template parameters are types
27805 for us (since TYPE_P holds true for them) so we handle
27806 them here. */
27810 /* -- a qualified-id with a nested-name-specifier which contains a
27811 class-name that names a dependent type or whose unqualified-id
27812 names a dependent type. */
27816 /* An alias template specialization can be dependent even if the
27817 resulting type is not. */
27821 /* -- a cv-qualified type where the cv-unqualified type is
27822 dependent.
27823 No code is necessary for this bullet; the code below handles
27824 cv-qualified types, and we don't want to strip aliases with
27825 TYPE_MAIN_VARIANT because of DR 1558. */
27826 /* -- a compound type constructed from any dependent type. */
27834 {
27835 tree arg_type;
27840 arg_type;
27846 /* A value-dependent noexcept-specifier makes the type dependent. */
27849 }
27850 /* -- an array type constructed from any dependent type or whose
27851 size is specified by a constant expression that is
27852 value-dependent.
27854 We checked for type- and value-dependence of the bounds in
27855 compute_array_index_type, so TYPE_DEPENDENT_P is already set. */
27857 {
27862 }
27864 /* -- a template-id in which either the template name is a template
27865 parameter ... */
27868 /* ... or any of the template arguments is a dependent type or
27869 an expression that is type-dependent or value-dependent. */
27871 && (any_dependent_template_arguments_p
27875 /* All TYPEOF_TYPEs, DECLTYPE_TYPEs, and TRAIT_TYPEs are
27876 dependent; if the argument of the `typeof' expression is not
27877 type-dependent, then it should already been have resolved. */
27883 /* A template argument pack is dependent if any of its packed
27884 arguments are. */
27886 {
27891 }
27893 /* All TYPE_PACK_EXPANSIONs are dependent, because parameter packs must
27894 be template parameters. */
27904 /* The standard does not specifically mention types that are local
27905 to template functions or local classes, but they should be
27906 considered dependent too. For example:
27908 template <int I> void f() {
27909 enum E { a = I };
27910 S<sizeof (E)> s;
27911 }
27913 The size of `E' cannot be known until the value of `I' has been
27914 determined. Therefore, `E' must be considered dependent. */
27918 /* Don't use type_dependent_expression_p here, as it can lead
27919 to infinite recursion trying to determine whether a lambda
27920 nested in a lambda is dependent (c++/47687). */
27924 && (any_dependent_template_arguments_p
27928 /* Other types are non-dependent. */
27930 }
27932 /* Returns TRUE if TYPE is dependent, in the sense of
27933 [temp.dep.type]. Note that a NULL type is considered dependent. */
27935 bool
27937 {
27938 /* If there are no template parameters in scope, then there can't be
27939 any dependent types. */
27941 {
27942 /* If we are not processing a template, then nobody should be
27943 providing us with a dependent type. */
27947 }
27949 /* If the type is NULL, we have not computed a type for the entity
27950 in question; in that case, the type is dependent. */
27954 /* Erroneous types can be considered non-dependent. */
27958 /* If we have not already computed the appropriate value for TYPE,
27959 do so now. */
27961 {
27964 }
27967 }
27969 /* Returns TRUE if SCOPE is a dependent scope, in which we can't do any
27970 lookup. In other words, a dependent type that is not the current
27971 instantiation. */
27973 bool
27975 {
27978 }
27980 /* True if we might find more declarations in SCOPE during instantiation than
27981 we can when parsing the template. */
27983 bool
27985 {
27987 }
27989 /* T is a SCOPE_REF. Return whether it represents a non-static member of
27990 an unknown base of 'this' (and is therefore instantiation-dependent). */
27992 static bool
27994 {
28011 }
28013 /* T is a SCOPE_REF; return whether we need to consider it
28014 instantiation-dependent so that we can check access at instantiation
28015 time even though we know which member it resolves to. */
28017 static bool
28019 {
28027 else
28029 }
28031 /* Returns TRUE if the EXPRESSION is value-dependent, in the sense of
28032 [temp.dep.constexpr]. EXPRESSION is already known to be a constant
28033 expression. */
28035 /* Note that this predicate is not appropriate for general expressions;
28036 only constant expressions (that satisfy potential_constant_expression)
28037 can be tested for value dependence. */
28039 bool
28041 {
28045 /* A type-dependent expression is also value-dependent. */
28050 {
28052 /* A dependent member function of the current instantiation. */
28056 /* A dependent member function of the current instantiation. */
28063 /* A name that has not been looked up -- must be dependent. */
28067 /* A non-type template parm. */
28071 /* A non-type template parm. */
28077 /* A constant with literal type and is initialized
28078 with an expression that is value-dependent. */
28082 {
28085 /* __PRETTY_FUNCTION__ inside a template function is dependent
28086 on the name of the function. */
28088 /* It might be used in a template, but not a template
28089 function, in which case its DECL_VALUE_EXPR will be
28090 "top level". */
28093 }
28095 /* FIXME cp_finish_decl doesn't fold reference initializers. */
28097 /* We have a constexpr variable and we're processing a template. When
28098 there's lifetime extension involved (for which finish_compound_literal
28099 used to create a temporary), we'll not be able to evaluate the
28100 variable until instantiating, so pretend it's value-dependent. */
28112 /* These expressions are value-dependent if the type to which
28113 the cast occurs is dependent or the expression being casted
28114 is value-dependent. */
28115 {
28121 /* A functional cast has a list of operands. */
28124 {
28125 /* If there are no operands, it must be an expression such
28126 as "int()". This should not happen for aggregate types
28127 because it would form non-constant expressions. */
28132 }
28142 }
28147 /* FALLTHRU */
28150 /* A `sizeof' expression is value-dependent if the operand is
28151 type-dependent or is a pack expansion. */
28160 /* An 'encode' expression is value-dependent if the operand is
28161 type-dependent. */
28170 /* All instantiation-dependent expressions should also be considered
28171 value-dependent. */
28179 /* A NONTYPE_ARGUMENT_PACK is value-dependent if any packed argument
28180 is value-dependent. */
28187 {
28203 }
28214 {
28218 }
28221 /* Treat all requires-expressions as value-dependent so
28222 we don't try to fold them. */
28229 {
28236 {
28238 /* In a call to a constexpr member function, look through the
28239 implicit ADDR_EXPR on the object argument so that it doesn't
28240 cause the call to be considered value-dependent. We also
28241 look through it in potential_constant_expression. */
28248 }
28250 }
28257 {
28259 tree val;
28266 }
28269 /* Treat a GNU statement expression as dependent to avoid crashing
28270 under instantiate_non_dependent_expr; it can't be constant. */
28275 /* The second operand is a type, which type_dependent_expression_p
28276 (and therefore value_dependent_expression_p) doesn't want to see. */
28282 /* A constant expression is value-dependent if any subexpression is
28283 value-dependent. */
28285 {
28292 {
28296 {
28299 /* In some cases, some of the operands may be missing.
28300 (For example, in the case of PREDECREMENT_EXPR, the
28301 amount to increment by may be missing.) That doesn't
28302 make the expression dependent. */
28305 }
28306 }
28310 }
28312 }
28314 /* The expression is not value-dependent. */
28316 }
28318 /* Returns TRUE if the EXPRESSION is type-dependent, in the sense of
28319 [temp.dep.expr]. Note that an expression with no type is
28320 considered dependent. Other parts of the compiler arrange for an
28321 expression with type-dependent subexpressions to have no type, so
28322 this function doesn't have to be fully recursive. */
28324 bool
28326 {
28337 /* An unresolved name is always dependent. */
28343 /* A lambda-expression in template context is dependent. dependent_type_p is
28344 true for a lambda in the scope of a class or function template, but that
28345 doesn't cover all template contexts, like a default template argument. */
28349 /* A fold expression is type-dependent. */
28356 /* Some expression forms are never type-dependent. */
28369 /* The types of these expressions depends only on the type to which
28370 the cast occurs. */
28379 /* The types of these expressions depends only on the type created
28380 by the expression. */
28383 {
28384 /* For NEW_EXPR tree nodes created inside a template, either
28385 the object type itself or a TREE_LIST may appear as the
28386 operand 1. */
28389 /* This is an array type. We need to check array dimensions
28390 as well. */
28392 || value_dependent_expression_p
28394 /* Array type whose dimension has to be deduced. */
28398 else
28400 }
28403 {
28407 /* 14.6.2.2 [temp.dep.expr]: An id-expression is type-dependent if it
28408 contains an identifier associated by name lookup with one or more
28409 declarations declared with a dependent type, or...a
28410 nested-name-specifier or qualified-id that names a member of an
28411 unknown specialization. */
28414 }
28424 {
28429 }
28431 /* A static data member of the current instantiation with incomplete
28432 array type is type-dependent, as the definition and specializations
28433 can have different bounds. */
28440 /* An array of unknown bound depending on a variadic parameter, eg:
28442 template<typename... Args>
28443 void foo (Args... args)
28444 {
28445 int arr[] = { args... };
28446 }
28448 template<int... vals>
28449 void bar ()
28450 {
28451 int arr[] = { vals... };
28452 }
28454 If the array has no length and has an initializer, it must be that
28455 we couldn't determine its length in cp_complete_array_type because
28456 it is dependent. */
28464 /* Pull a FUNCTION_DECL out of a BASELINK if we can. */
28466 {
28471 }
28473 /* A function or variable template-id is type-dependent if it has any
28474 dependent template arguments. */
28478 {
28479 /* Consider the innermost template arguments, since those are the ones
28480 that come from the template-id; the template arguments for the
28481 enclosing class do not make it type-dependent unless they are used in
28482 the type of the decl. */
28484 && (any_dependent_template_arguments_p
28487 }
28489 /* Otherwise, if the function decl isn't from a dependent scope, it can't be
28490 type-dependent. Checking this is important for functions with auto return
28491 type, which looks like a dependent type. */
28500 {
28504 }
28506 /* Otherwise, its constraints could still depend on outer template parameters
28507 from its (dependent) scope. */
28509 /* As an optimization, check this cheaper sufficient condition first.
28510 (At this point we've established that we're looking at a member of
28511 a dependent class, so it makes sense to start treating say undeduced
28512 auto as dependent.) */
28517 /* Always dependent, on the number of arguments if nothing else. */
28522 {
28527 {
28533 }
28534 /* SCOPE_REF with non-null TREE_TYPE is always non-dependent. */
28538 /* CO_AWAIT/YIELD_EXPR with unknown type is always dependent. */
28544 {
28549 }
28552 {
28559 }
28568 }
28570 /* The type of a non-type template parm declared with a placeholder type
28571 depends on the corresponding template argument, even though
28572 placeholders are not normally considered dependent. */
28579 /* Dependent type attributes might not have made it from the decl to
28580 the type yet. */
28586 }
28588 /* [temp.dep.expr]/5: A class member access expression (5.2.5) is
28589 type-dependent if the expression refers to a member of the current
28590 instantiation and the type of the referenced member is dependent, or the
28591 class member access expression refers to a member of an unknown
28592 specialization.
28594 This function returns true if the OBJECT in such a class member access
28595 expression is of an unknown specialization. */
28597 bool
28599 {
28600 /* An IDENTIFIER_NODE can sometimes have a TREE_TYPE, but it's still
28601 dependent. */
28606 }
28608 /* walk_tree callback function for instantiation_dependent_expression_p,
28609 below. Returns non-zero if a dependent subexpression is found. */
28611 static tree
28614 {
28616 {
28617 /* We don't have to worry about decltype currently because decltype
28618 of an instantiation-dependent expr is a dependent type. This
28619 might change depending on the resolution of DR 1172. */
28622 }
28625 {
28626 /* Don't treat an argument list as dependent just because it has no
28627 TREE_TYPE. */
28638 /* We'll check value-dependence separately. */
28641 /* Handle expressions with type operands. */
28646 {
28651 {
28654 else
28655 {
28658 }
28659 }
28661 }
28665 /* In a template, finish_class_member_access_expr creates a
28666 COMPONENT_REF with an IDENTIFIER_NODE for op1 even if it isn't
28667 type-dependent, so that we can check access control at
28668 instantiation time (PR 42277). See also Core issue 1273. */
28675 else
28678 /* Treat statement-expressions as dependent. */
28682 /* Treat requires-expressions as dependent. */
28693 /* Before C++17, a noexcept-specifier isn't part of the function type
28694 so it doesn't affect type dependence, but we still want to consider it
28695 for instantiation dependence. */
28704 }
28708 else
28710 }
28712 /* Returns TRUE if the EXPRESSION is instantiation-dependent, in the
28713 sense defined by the ABI:
28715 "An expression is instantiation-dependent if it is type-dependent
28716 or value-dependent, or it has a subexpression that is type-dependent
28717 or value-dependent."
28719 Except don't actually check value-dependence for unevaluated expressions,
28720 because in sizeof(i) we don't care about the value of i. Checking
28721 type-dependence will in turn check value-dependence of array bounds/template
28722 arguments as needed. */
28724 bool
28726 {
28727 tree result;
28738 }
28740 /* As above, but also check value-dependence of the expression as a whole. */
28742 bool
28744 {
28746 || (processing_template_decl
28749 }
28751 /* Like type_dependent_expression_p, but it also works while not processing
28752 a template definition, i.e. during substitution or mangling. */
28754 bool
28756 {
28762 }
28764 /* Returns TRUE if ARGS contains a type-dependent expression. */
28766 bool
28768 {
28777 }
28779 /* Returns TRUE if LIST (a TREE_LIST whose TREE_VALUEs are
28780 expressions) contains any type-dependent expressions. */
28782 bool
28784 {
28790 }
28792 /* Returns TRUE if LIST (a TREE_LIST whose TREE_VALUEs are
28793 expressions) contains any value-dependent expressions. */
28795 bool
28797 {
28803 }
28805 /* Returns TRUE if the ARG (a template argument) is dependent. */
28807 bool
28809 {
28813 /* Assume a template argument that was wrongly written by the user
28814 is dependent. This is consistent with what
28815 any_dependent_template_arguments_p [that calls this function]
28816 does. */
28826 {
28829 /* A member template of a dependent class is not necessarily
28830 type-dependent, but it is a dependent template argument because it
28831 will be a member of an unknown specialization to that template. */
28834 }
28836 {
28842 }
28845 else
28847 }
28849 /* Identify any expressions that use function parms. */
28851 static tree
28853 {
28856 {
28859 }
28861 }
28863 /* Returns true if a type specialization formed using the template
28864 arguments ARGS needs to use structural equality. */
28866 bool
28868 {
28878 {
28881 {
28887 {
28888 /* Look inside the argument pack. */
28891 }
28894 {
28903 /* An any_targ_node argument (added by add_defaults_to_ttp)
28904 makes the corresponding specialization not canonicalizable,
28905 since template_args_equal always return true for it. We
28906 may see this when called from bind_template_template_parm. */
28908 /* Checking current_function_decl because this structural
28909 comparison is only necessary for redeclaration. */
28912 && (cp_walk_tree_without_duplicates
28914 /* The identity of a class template specialization that uses
28915 a function parameter depends on the identity of the function.
28916 And if this specialization appeared in the trailing return
28917 type thereof, we don't know the identity of the function
28918 (e.g. if it's a redeclaration or a new function) until we
28919 form its signature and go through duplicate_decls. Thus
28920 it's unsafe to decide on a canonical type now (which depends
28921 on the DECL_CONTEXT of the function parameter, which can get
28922 mutated after the fact by duplicate_decls), so just require
28923 structural equality in this case (PR52830). */
28928 /* Require structural equality for specializations written
28929 in terms of a dependent alias template specialization. */
28934 /* Require structural equality for specializations written
28935 in terms of a class template specialization that itself
28936 needs structural equality. */
28938 }
28939 }
28940 }
28943 }
28945 /* Returns true if ARGS (a collection of template arguments) contains
28946 any dependent arguments. */
28948 bool
28950 {
28957 {
28962 }
28965 }
28967 /* Returns true if ARGS contains any errors. */
28969 bool
28971 {
28979 {
28982 else
28984 }
28990 {
28995 }
28998 }
29000 /* Returns TRUE if the template TMPL is type-dependent. */
29002 bool
29004 {
29006 {
29011 }
29013 /* Template template parameters are dependent. */
29017 /* So are names that have not been looked up. */
29021 }
29023 /* Returns TRUE if the specialization TMPL<ARGS> is dependent. */
29025 bool
29027 {
29030 }
29032 /* Returns TRUE if OMP_FOR with DECLV, INITV, CONDV and INCRV vectors
29033 are dependent. */
29035 bool
29037 {
29044 {
29069 {
29073 }
29077 {
29081 {
29087 /* If this loop has a class iterator with != comparison
29088 with increment other than i++/++i/i--/--i, make sure the
29089 increment is constant. */
29092 {
29095 else
29099 }
29100 }
29101 }
29102 }
29105 }
29107 /* TYPE is a TYPENAME_TYPE. Returns the ordinary TYPE to which the
29108 TYPENAME_TYPE corresponds. Returns the original TYPENAME_TYPE if
29109 no such TYPE can be found. Note that this function peers inside
29110 uninstantiated templates and therefore should be used only in
29111 extremely limited situations. ONLY_CURRENT_P restricts this
29112 peering to the currently open classes hierarchy (which is required
29113 when comparing types). */
29115 tree
29117 {
29118 tree scope;
29119 tree name;
29120 tree decl;
29122 tree pushed_scope;
29123 tree result;
29128 /* We shouldn't have built a TYPENAME_TYPE with a non-dependent scope. */
29131 /* Usually the non-qualified identifier of a TYPENAME_TYPE is
29132 TYPE_IDENTIFIER (type). But when 'type' is a typedef variant of a
29133 TYPENAME_TYPE node, then TYPE_NAME (type) is set to the TYPE_DECL
29134 representing the typedef. In that case TYPE_IDENTIFIER (type) is
29135 not the non-qualified identifier of the TYPENAME_TYPE anymore.
29136 So by getting the TYPE_IDENTIFIER of the _main declaration_ of
29137 the TYPENAME_TYPE instead, we avoid messing up with a possible
29138 typedef variant case. */
29141 /* If the SCOPE is itself a TYPENAME_TYPE, then we need to resolve
29142 it first before we can figure out what NAME refers to. */
29144 {
29146 /* Given a class template A with a dependent base with nested type C,
29147 typedef typename A::C::C C will land us here, as trying to resolve
29148 the initial A::C leads to the local C typedef, which leads back to
29149 A::C::C. So we break the recursion now. */
29151 else
29153 }
29154 /* If we don't know what SCOPE refers to, then we cannot resolve the
29155 TYPENAME_TYPE. */
29158 /* If this is a typedef, we don't want to look inside (c++/11987). */
29161 /* If SCOPE isn't the template itself, it will not have a valid
29162 TYPE_FIELDS list. */
29164 /* scope is either the template itself or a compatible instantiation
29165 like X<T>, so look up the name in the original template. */
29167 /* If scope has no fields, it can't be a current instantiation. Check this
29168 before currently_open_class to avoid infinite recursion (71515). */
29171 /* If the SCOPE is not the current instantiation, there's no reason
29172 to look inside it. */
29175 /* Enter the SCOPE so that name lookup will be resolved as if we
29176 were in the class definition. In particular, SCOPE will no
29177 longer be considered a dependent type. */
29179 /* Look up the declaration. */
29181 tf_warning_or_error);
29185 /* For a TYPENAME_TYPE like "typename X::template Y<T>", we want to
29186 find a TEMPLATE_DECL. Otherwise, we want to find a TYPE_DECL. */
29192 {
29196 }
29199 {
29200 /* Obtain the template and the arguments. */
29203 {
29204 /* We get here with a plain identifier because a previous tentative
29205 parse of the nested-name-specifier as part of a ptr-operator saw
29206 ::template X<A>. The use of ::template is necessary in a
29207 ptr-operator, but wrong in a declarator-id.
29209 [temp.names]: In a qualified-id of a declarator-id, the keyword
29210 template shall not appear at the top level. */
29214 }
29216 /* Instantiate the template. */
29222 }
29224 /* Leave the SCOPE. */
29228 /* If we failed to resolve it, return the original typename. */
29232 /* If lookup found a typename type, resolve that too. */
29234 {
29235 /* Ill-formed programs can cause infinite recursion here, so we
29236 must catch that. */
29240 }
29242 /* Qualify the resulting type. */
29248 }
29250 /* Returns a type which represents 'auto' or 'decltype(auto)'. We use a
29251 TEMPLATE_TYPE_PARM with a level one deeper than the actual template parms,
29252 by default. If set_canonical is true, we set TYPE_CANONICAL on it. */
29254 static tree
29256 {
29272 }
29274 tree
29276 {
29278 }
29280 tree
29282 {
29284 }
29286 /* Return a C++17 deduction placeholder for class template TMPL.
29287 There are represented as an 'auto' with the special level 0 and
29288 CLASS_PLACEHOLDER_TEMPLATE set. */
29290 tree
29292 {
29295 /* Our canonical type depends on the placeholder. */
29298 }
29300 /* True iff T is a C++17 class template deduction placeholder. */
29302 bool
29304 {
29306 }
29308 /* Make a "constrained auto" type-specifier. This is an auto or
29309 decltype(auto) type with constraints that must be associated after
29310 deduction. The constraint is formed from the given concept CON
29311 and its optional sequence of template arguments ARGS.
29313 TYPE must be the result of make_auto_type or make_decltype_auto_type. */
29315 static tree
29317 {
29318 /* Build the constraint. */
29330 /* Our canonical type depends on the constraint. */
29333 /* Attach the constraint to the type declaration. */
29335 }
29337 /* Make a "constrained auto" type-specifier. */
29339 tree
29341 {
29344 }
29346 /* Make a "constrained decltype(auto)" type-specifier. */
29348 tree
29350 {
29353 }
29355 /* Returns true if the placeholder type constraint T has any dependent
29356 (explicit) template arguments. */
29358 static bool
29360 {
29365 {
29368 }
29375 }
29377 /* Build and return a concept definition. Like other templates, the
29378 CONCEPT_DECL node is wrapped by a TEMPLATE_DECL. This returns the
29379 the TEMPLATE_DECL. */
29381 tree
29383 {
29389 /* A concept-definition shall not have associated constraints. */
29391 {
29394 }
29396 /* A concept-definition shall appear in namespace scope. Templates
29397 aren't allowed in block scope, so we only need to check for class
29398 scope. */
29400 {
29403 }
29406 {
29409 }
29411 /* Initially build the concept declaration; its type is bool. */
29421 /* Push the enclosing template. */
29423 }
29425 /* Given type ARG, return std::initializer_list<ARG>. */
29427 static tree
29429 {
29434 {
29438 "deducing from brace-enclosed initializer list"
29442 }
29448 }
29450 /* Replace auto in TYPE with std::initializer_list<auto>. */
29452 static tree
29454 {
29461 }
29463 /* Hash traits for hashing possibly constrained 'auto'
29464 TEMPLATE_TYPE_PARMs for use by do_auto_deduction. */
29467 {
29470 };
29472 /* Hash the 'auto' T. */
29474 inline hashval_t
29476 {
29478 /* Matching constrained-type-specifiers denote the same template
29479 parameter, so hash the constraint. */
29481 else
29482 /* But unconstrained autos are all separate, so just hash the pointer. */
29484 }
29486 /* Compare two 'auto's. */
29490 {
29497 /* Two unconstrained autos are distinct. */
29502 }
29504 /* for_each_template_parm callback for extract_autos: if t is a (possibly
29505 constrained) auto, add it to the vector. */
29507 static int
29509 {
29512 {
29513 /* All the autos were built with index 0; fix that up now. */
29517 /* If this is a repeated constrained-type-specifier, use the index we
29518 chose before. */
29520 else
29521 {
29522 /* Otherwise this is new, so use the current count. */
29525 }
29527 {
29532 }
29533 }
29535 /* Always keep walking. */
29537 }
29539 /* Return a TREE_VEC of the 'auto's used in type under the Concepts TS, which
29540 says they can appear anywhere in the type. */
29542 static tree
29544 {
29552 {
29556 }
29559 }
29561 /* The stem for deduction guide names. */
29564 /* Return the name for a deduction guide for class template TMPL. */
29566 tree
29568 {
29579 }
29581 /* True if NAME is the name of a deduction guide. */
29583 bool
29585 {
29589 }
29591 /* True if FN is a deduction guide. */
29593 bool
29595 {
29600 }
29602 /* True if FN is the copy deduction guide, i.e. A(A)->A. */
29604 bool
29606 {
29613 }
29615 /* True if FN is a guide generated from a constructor template. */
29617 bool
29619 {
29627 }
29629 /* True if FN is an aggregate initialization guide or the copy deduction
29630 guide. */
29632 bool
29634 {
29638 /* Explicitly declared. */
29641 /* Derived from a constructor. */
29644 }
29646 /* OLDDECL is a _DECL for a template parameter. Return a similar parameter at
29647 LEVEL:INDEX, using tsubst_args and complain for substitution into non-type
29648 template parameter types. Note that the handling of template template
29649 parameters relies on current_template_parms being set appropriately for the
29650 new template. */
29652 static tree
29655 {
29661 tree newtype;
29664 {
29668 }
29669 else
29670 {
29673 {
29674 // Substitute once to fix references to other template parameters.
29677 // Now substitute again to reduce the level of the auto.
29680 }
29681 else
29684 }
29686 tree newdecl
29691 tree newidx;
29694 {
29703 {
29704 tree newresult
29709 // First create a copy (ttargs) of tsubst_args with an
29710 // additional level for the template template parameter's own
29711 // template parameters (ttparms).
29712 tree ttparms = (INNERMOST_TEMPLATE_PARMS
29720 // Substitute ttargs into ttparms to fix references to
29721 // other template parameters.
29724 // Now substitute again with args based on tparms, to reduce
29725 // the level of the ttparms.
29728 complain);
29729 // Finally, tack the adjusted parms onto tparms.
29732 // As with all template template parms, the parameter list captured
29733 // by this template template parm that corresponds to its own level
29734 // should be empty. This avoids infinite recursion when structurally
29735 // comparing two such rewritten template template parms (PR102479).
29740 // All done.
29744 }
29748 else
29750 }
29751 else
29752 {
29754 tree newconst
29766 }
29769 }
29771 /* As rewrite_template_parm, but for the whole TREE_LIST representing a
29772 template parameter. */
29774 static tree
29777 {
29792 }
29794 /* Returns a C++17 class deduction guide template based on the constructor
29795 CTOR. As a special case, CTOR can be a RECORD_TYPE for an implicit default
29796 guide, REFERENCE_TYPE for an implicit copy/move guide, or TREE_LIST for an
29797 aggregate initialization guide. OUTER_ARGS are the template arguments
29798 for the enclosing scope of the class. */
29800 static tree
29802 {
29806 location_t loc;
29810 {
29814 }
29817 {
29819 {
29823 else
29825 }
29828 else
29838 }
29839 else
29840 {
29846 fn_tmpl
29854 /* If type is a member class template, DECL_TI_ARGS (ctor) will have
29855 fully specialized args for the enclosing class. Strip those off, as
29856 the deduction guide won't have those template parameters. */
29859 /* Discard the 'this' parameter. */
29867 {
29870 /* For a member template constructor, we need to flatten the two
29871 template parameter lists into one, and then adjust the function
29872 signature accordingly. This gets...complicated. */
29875 /* For a member template we should have two levels of parms/args, one
29876 for the class and one for the constructor. We stripped
29877 specialized args for further enclosing classes above. */
29881 /* Template args for translating references to the two-level template
29882 parameters into references to the one-level template parameters we
29883 are creating. */
29888 /* Template parms for the constructor template. */
29891 /* Template parms for the class template. */
29895 /* Template parms for the deduction guide start as a copy of the
29896 template parms for the class. We set current_template_parms for
29897 lookup_template_class_1. */
29903 /* Now we need to rewrite the constructor parms to append them to the
29904 class parms. */
29906 {
29910 tree newelt
29916 }
29918 /* Now we have a final set of template parms to substitute into the
29919 function signature. */
29926 {
29928 /* FIXME: We'd like to avoid substituting outer template
29929 arguments into the constraint ahead of time, but the
29930 construction of tsubst_args assumes that outer arguments
29931 are already substituted in. */
29934 }
29936 /* Parms are to have DECL_CHAIN tsubsted, which would be skipped if
29937 cp_unevaluated_operand. */
29938 cp_evaluated ev;
29941 }
29942 else
29943 {
29944 /* Substitute in the same arguments to rewrite class members into
29945 references to members of an unknown specialization. */
29946 cp_evaluated ev;
29950 {
29952 /* FIXME: As above. */
29955 }
29956 }
29961 }
29964 {
29965 /* Copy the parms so we can set DECL_PRIMARY_TEMPLATE. */
29969 }
29973 FUNCTION_DECL,
29988 }
29990 /* Add to LIST the member types for the reshaped initializer CTOR. */
29992 static tree
29994 {
29998 {
30002 {
30008 }
30012 /* Give the trailing pack expansion parameter a default argument to
30013 match aggregate initialization behavior, even if we deduce the
30014 length of the pack separately to more than we have initializers. */
30016 /* if ei is of array type and xi is a braced-init-list or string literal,
30017 Ti is an rvalue reference to the declared type of ei */
30022 {
30024 ftype = cp_build_qualified_type
30026 ftype = (cp_build_reference_type
30028 }
30030 }
30033 }
30035 /* Return whether ETYPE is, or is derived from, a specialization of TMPL. */
30037 static bool
30039 {
30045 tree tparms = (INNERMOST_TEMPLATE_PARMS
30052 }
30054 /* Return a C++20 aggregate deduction candidate for TYPE initialized from
30055 INIT. */
30057 static tree
30059 {
30067 {
30073 }
30075 /* We might be creating a guide for a class member template, e.g.,
30077 template<typename U> struct A {
30078 template<typename T> struct B { T t; };
30079 };
30081 At this point, A will have been instantiated. Below, we need to
30082 use both A<U>::B<T> (TEMPLATE_TYPE) and A<int>::B<T> (TYPE) types. */
30083 const bool member_template_p
30087 tree template_type = (member_template_p
30093 /* No aggregate candidate for copy-initialization. */
30095 {
30099 }
30101 /* If we encounter a problem, we just won't add the candidate. */
30106 {
30111 /* If we're creating a deduction guide for a member class template,
30112 we've used the original template pattern type for the reshape_init
30113 above; this is done because we want PARMS to be a template parameter
30114 type, something that can be deduced when used as a function template
30115 parameter. At this point the outer class template has already been
30116 partially instantiated (we deferred the deduction until the enclosing
30117 scope is non-dependent). Therefore we have to partially instantiate
30118 PARMS, so that its template level is properly reduced and we don't get
30119 mismatches when deducing types using the guide with PARMS. */
30121 {
30125 }
30126 }
30128 {
30131 len;
30133 {
30139 }
30140 }
30141 else
30142 /* Aggregate initialization doesn't apply to an initializer expression. */
30146 {
30152 }
30155 }
30157 /* UGUIDES are the deduction guides for the underlying template of alias
30158 template TMPL; adjust them to be deduction guides for TMPL.
30160 This routine also handles C++23 inherited CTAD, in which case TMPL is a
30161 TREE_LIST representing a synthetic alias template whose TREE_PURPOSE is
30162 the template parameter list of the alias template (equivalently, of the
30163 derived class) and TREE_VALUE the defining-type-id (equivalently, the
30164 base whose guides we're inheriting). UGUIDES are the base's guides. */
30166 static tree
30168 {
30169 /* [over.match.class.deduct]: When resolving a placeholder for a deduced
30170 class type (9.2.8.2) where the template-name names an alias template A,
30171 the defining-type-id of A must be of the form
30173 typename(opt) nested-name-specifier(opt) template(opt) simple-template-id
30175 as specified in 9.2.8.2. The guides of A are the set of functions or
30176 function templates formed as follows. For each function or function
30177 template f in the guides of the template named by the simple-template-id
30178 of the defining-type-id, the template arguments of the return type of f
30179 are deduced from the defining-type-id of A according to the process in
30180 13.10.2.5 with the exception that deduction does not fail if not all
30181 template arguments are deduced. Let g denote the result of substituting
30182 these deductions into f. If substitution succeeds, form a function or
30183 function template f' with the following properties and add it to the set
30184 of guides of A:
30186 * The function type of f' is the function type of g.
30188 * If f is a function template, f' is a function template whose template
30189 parameter list consists of all the template parameters of A (including
30190 their default template arguments) that appear in the above deductions or
30191 (recursively) in their default template arguments, followed by the
30192 template parameters of f that were not deduced (including their default
30193 template arguments), otherwise f' is not a function template.
30195 * The associated constraints (13.5.2) are the conjunction of the
30196 associated constraints of g and a constraint that is satisfied if and only
30197 if the arguments of A are deducible (see below) from the return type.
30199 * If f is a copy deduction candidate (12.4.1.8), then f' is considered to
30200 be so as well.
30202 * If f was generated from a deduction-guide (12.4.1.8), then f' is
30203 considered to be so as well.
30205 * The explicit-specifier of f' is the explicit-specifier of g (if
30206 any). */
30211 {
30216 }
30217 else
30218 {
30223 }
30230 {
30237 {
30241 /* Deduce template arguments for f from the type-id of A. */
30247 /* CWG2664: Discard any deductions, still build the guide. */
30251 /* The number of parms for f' is the number of parms of A used in
30252 the deduced arguments plus non-deduced parms of f. */
30264 /* Set current_template_parms as in build_deduction_guide. */
30272 /* First copy over the used parms of A. */
30275 {
30278 {
30283 }
30284 }
30287 /* Adjust the deduced template args for f to refer to the A parms
30288 with their new indexes. */
30292 /* Now rewrite the non-deduced parms of f. */
30295 {
30302 }
30305 /* Substitute the deduced arguments plus the rewritten template
30306 parameters into f to get g. This covers the type, copyness,
30307 guideness, and explicit-specifier. */
30308 tree g;
30309 {
30310 /* Parms are to have DECL_CHAIN tsubsted, which would be skipped
30311 if cp_unevaluated_operand. */
30312 cp_evaluated ev;
30315 }
30319 {
30320 /* The targs are all non-dependent, so g isn't a template. */
30324 }
30333 /* Substitute the associated constraints. */
30340 /* Add a constraint that the return type matches the instantiation of
30341 A with the same template arguments. */
30345 /* FIXME this should mean they don't compare as equivalent. */
30347 {
30350 }
30353 {
30356 }
30357 }
30358 else
30359 {
30360 /* For a non-template deduction guide, if the arguments of A aren't
30361 deducible from the return type, don't add the candidate. */
30362 non_template:
30366 }
30368 /* Rewrite the return type of the inherited guide in terms of the
30369 derived class. This is specified as replacing the return type R
30370 with typename CC<R>::type where the partially specialized CC maps a
30371 base class specialization to a specialization of the derived class
30372 having such a base (inducing substitution failure if no such derived
30373 class exists).
30375 As specified this mapping would be done at instantiation time using
30376 non-dependent template arguments, but we do it ahead of time using
30377 the generic arguments. This seems to be good enough since generic
30378 deduction should succeed only if concrete deduction would. */
30380 {
30398 }
30401 }
30404 }
30406 /* CTOR is a using-decl inheriting the constructors of some base of the class
30407 template TMPL; adjust the base's guides be deduction guides for TMPL. */
30409 static tree
30411 {
30412 /* [over.match.class.deduct]: In addition, if C is defined and inherits
30413 constructors ([namespace.udecl]) from a direct base class denoted in the
30414 base-specifier-list by a class-or-decltype B, let A be an alias template
30415 whose template parameter list is that of C and whose defining-type-id is
30416 B. If A is a deducible template ([dcl.type.simple]), the set contains the
30417 guides of A with the return type R of each guide replaced with typename
30418 CC::type given a class template
30420 template <typename> class CC;
30422 whose primary template is not defined and with a single partial
30423 specialization whose template parameter list is that of A and whose
30424 template argument list is a specialization of A with the template argument
30425 list of A ([temp.dep.type]) having a member typedef type designating a
30426 template specialization with the template argument list of A but with C as
30427 the template. */
30429 /* FIXME: Also recognize inherited constructors of the form 'using C::B::B',
30430 which seem to be represented with TYPENAME_TYPE C::B as USING_DECL_SCOPE?
30431 And recognize constructors inherited from a non-dependent base class, which
30432 seem to be missing from the overload set entirely? */
30444 }
30446 /* If template arguments for TMPL can be deduced from TYPE, return
30447 the deduced arguments, otherwise return NULL_TREE.
30448 Used to implement CPTK_IS_DEDUCIBLE for alias CTAD according to
30449 [over.match.class.deduct].
30451 This check is specified in terms of partial specialization, so the behavior
30452 should be parallel to that of get_partial_spec_bindings. */
30454 tree
30456 {
30459 {
30460 /* If tmpl is a class template, this is trivial: it's deducible if
30461 TYPE is a specialization of TMPL. */
30463 {
30468 else
30470 }
30472 /* Otherwise it's an alias template. */
30475 }
30476 else
30477 {
30478 /* TMPL is a synthetic alias template represented as a TREE_LIST as
30479 per alias_ctad_tweaks. */
30483 }
30489 again:
30494 /* We don't fail on an undeduced targ the second time through (like
30495 get_partial_spec_bindings) because we're going to try defaults. */
30498 {
30504 {
30509 }
30510 /* If the type parameter is a parameter pack, then it will be deduced
30511 to an empty parameter pack. This is another case that doesn't model
30512 well as partial specialization. */
30514 {
30515 tree arg;
30517 {
30520 }
30521 else
30525 }
30526 }
30528 /* Maybe add in default template args. This seems like a flaw in the
30529 specification in terms of partial specialization, since it says the
30530 partial specialization has the the template parameter list of A, but a
30531 partial specialization can't have default targs. */
30536 /* I believe we don't need the template_template_parm_bindings_ok_p call
30537 because coerce_template_parms did coerce_template_template_parms. */
30543 }
30545 /* Return artificial deduction guides built from the constructors of class
30546 template TMPL. */
30548 static tree
30550 {
30557 {
30558 /* We handle C++23 inherited CTAD below. */
30564 }
30569 {
30573 }
30575 /* Add implicit default constructor deduction guide. */
30577 {
30579 complain);
30581 }
30583 /* Add copy guide. */
30584 {
30587 complain);
30589 }
30592 }
30596 /* Return the non-aggregate deduction guides for deducible template TMPL. The
30597 aggregate candidate is added separately because it depends on the
30598 initializer. Set ANY_DGUIDES_P if we find a non-implicit deduction
30599 guide. */
30601 static tree
30603 {
30606 {
30610 complain);
30611 }
30612 else
30613 {
30619 else
30621 }
30623 /* Cache the deduction guides for a template. We also remember the result of
30624 lookup, and rebuild everything if it changes; should be very rare. */
30625 /* FIXME: Also rebuild if this is a class template that inherits guides from a
30626 base class, and lookup for the latter changed. */
30630 {
30634 }
30635 else
30636 {
30639 }
30644 else
30645 {
30649 }
30653 }
30655 /* Return whether TMPL is a (class template argument-) deducible template. */
30657 bool
30659 {
30660 /* A deducible template is either a class template or is an alias template
30661 whose defining-type-id is of the form
30663 typename(opt) nested-name-specifier(opt) template(opt) simple-template-id
30665 where the nested-name-specifier (if any) is non-dependent and the
30666 template-name of the simple-template-id names a deducible template. */
30677 }
30679 /* Deduce template arguments for the class template placeholder PTYPE for
30680 template TMPL based on the initializer INIT, and return the resulting
30681 type. */
30683 static tree
30686 {
30687 /* We should have handled this in the caller. */
30691 /* If the class was erroneous, don't try to deduce, because that
30692 can generate a lot of diagnostic. */
30698 /* Wait until the enclosing scope is non-dependent. */
30703 /* Initializing one placeholder from another. */
30714 {
30718 }
30720 {
30722 {
30723 /* Be permissive with equivalent alias templates. */
30726 bool complained
30728 "alias template deduction only available "
30733 {
30736 }
30737 }
30738 else
30740 }
30742 /* Wait until the initializer is non-dependent. */
30746 /* Don't bother with the alias rules for an equivalent template. */
30759 {
30764 {
30765 /* As an exception, the first phase in 16.3.1.7 (considering the
30766 initializer list as a single argument) is omitted if the
30767 initializer list consists of a single expression of type cv U,
30768 where U is a specialization of C or a class derived from a
30769 specialization of C. */
30773 }
30776 else
30778 }
30781 else
30784 /* Do this now to avoid problems with erroneous args later on. */
30794 /* Prune explicit deduction guides in copy-initialization context (but
30795 not copy-list-initialization). */
30798 {
30804 {
30805 /* Found a nonconverting guide, prune the candidates. */
30812 }
30813 }
30821 /* If this is list-initialization and the class has a list guide, first
30822 try deducing from the list as a single argument, as [over.match.list]. */
30824 {
30832 {
30833 /* That didn't work, now try treating the list as a sequence of
30834 arguments. */
30840 }
30841 }
30844 {
30846 " of %qT, as it has no non-explicit deduction guides or "
30849 }
30851 {
30855 }
30861 {
30863 {
30869 }
30871 }
30872 /* [over.match.list]/1: In copy-list-initialization, if an explicit
30873 constructor is chosen, the initialization is ill-formed. */
30875 {
30877 {
30879 {
30880 // TODO: Pass down location from cp_finish_decl.
30882 "explicit deduction guide selected in "
30887 }
30889 }
30890 }
30892 /* If CTAD succeeded but the type doesn't have any explicit deduction
30893 guides, this deduction might not be what the user intended. */
30895 {
30899 "%qT may not intend to support class template argument "
30903 }
30907 }
30909 /* Return true if INIT is an unparenthesized id-expression or an
30910 unparenthesized class member access. Used for the argument of
30911 decltype(auto). */
30913 bool
30915 {
30918 /* We need to be able to tell '(r)' and 'r' apart (when it's of
30919 reference type). Only the latter is an id-expression. */
30927 }
30929 /* Replace occurrences of 'auto' in TYPE with the appropriate type deduced
30930 from INIT. AUTO_NODE is the TEMPLATE_TYPE_PARM used for 'auto' in TYPE.
30931 The CONTEXT determines the context in which auto deduction is performed
30932 and is used to control error diagnostics. FLAGS are the LOOKUP_* flags.
30934 OUTER_TARGS is used during template argument deduction (context == adc_unify)
30935 to properly substitute the result. It's also used in the adc_unify and
30936 adc_requirement contexts to communicate the necessary template arguments
30937 to satisfaction. OUTER_TARGS is ignored in other contexts.
30939 Additionally for adc_unify contexts TMPL is the template for which TYPE
30940 is a template parameter type.
30942 For partial-concept-ids, extra args from OUTER_TARGS, TMPL and the current
30943 scope may be appended to the list of deduced template arguments prior to
30944 determining constraint satisfaction as appropriate. */
30946 tree
30953 {
30959 /* Defining a subset of type-dependent expressions that we can deduce
30960 from ahead of time isn't worth the trouble. */
30963 /* Similarly, we can't deduce from another undeduced decl. */
30967 /* We may be doing a partial substitution, but we still want to replace
30968 auto_node. */
30972 {
30973 /* We don't recurse here because we can't deduce from a nested
30974 initializer_list. */
30978 }
30982 /* In C++23, we must deduce the type to int&& for code like
30983 decltype(auto) f(int&& x) { return (x); }
30984 or
30985 auto&& f(int x) { return x; }
30986 so we use treat_lvalue_as_rvalue_p. But don't do it for
30987 decltype(auto) f(int x) { return x; }
30988 where we should deduce 'int' rather than 'int&&'; transmogrifying
30989 INIT to an rvalue would break that. */
30990 tree r;
31000 /* C++17 class template argument deduction. */
31004 /* Nothing we can do with this, even in deduction context. */
31009 /* [dcl.spec.auto]: Obtain P from T by replacing the occurrences of auto
31010 with either a new invented type template parameter U or, if the
31011 initializer is a braced-init-list (8.5.4), with
31012 std::initializer_list<U>. */
31014 {
31019 else
31020 {
31022 {
31026 "for deduction to %<std::initializer_list%>, use copy-"
31028 }
31030 }
31031 }
31036 tree targs;
31040 {
31041 /* [dcl.struct.bind]/1 - if decomposition declaration has no ref-qualifiers
31042 and initializer has array type, deduce cv-qualified array type. */
31045 }
31047 {
31055 }
31056 else
31057 {
31062 tree tparms;
31066 else
31067 {
31071 }
31075 DEDUCE_CALL,
31078 {
31080 /* Try again at instantiation time. */
31084 /* If type is error_mark_node a diagnostic must have been
31085 emitted by now. Also, having a mention to '<type error>'
31086 in the diagnostic is not really useful to the user. */
31087 {
31090 && (auto_node
31094 init);
31095 else
31098 DEDUCE_CALL,
31100 }
31102 }
31103 }
31105 /* Check any placeholder constraints against the deduced type. */
31109 {
31111 {
31116 /* If the constraint is dependent, we need to wait until
31117 instantiation time to resolve the placeholder. */
31120 }
31127 {
31131 {
31132 /* As in satisfy_declaration_constraints. */
31136 else
31138 }
31139 }
31146 /* HACK: Compensate for callers not always communicating all levels of
31147 outer template arguments by filling in the outermost missing levels
31148 with dummy levels before checking satisfaction. We'll still crash
31149 if the constraint depends on a template argument belonging to one of
31150 these missing levels, but this hack otherwise allows us to handle a
31151 large subset of possible constraints (including all non-dependent
31152 constraints). */
31155 {
31160 }
31163 {
31165 {
31166 auto_diagnostic_group d;
31168 {
31186 }
31188 }
31190 }
31191 }
31194 /* The outer template arguments are already substituted into type
31201 }
31203 /* Substitutes LATE_RETURN_TYPE for 'auto' in TYPE and returns the
31204 result. */
31206 tree
31208 {
31210 {
31213 }
31217 {
31218 /* In an abbreviated function template we didn't know we were dealing
31219 with a function template when we saw the auto return type, so rebuild
31220 the return type using an auto with the correct level. */
31225 auto_vec);
31226 /* Also rebuild the constraint info in terms of the new auto. */
31234 }
31236 }
31238 /* Returns true iff TYPE is a TEMPLATE_TYPE_PARM representing 'auto' or
31239 'decltype(auto)' or a deduced class template. */
31241 bool
31243 {
31248 else
31250 }
31252 /* for_each_template_parm callback for type_uses_auto. */
31254 int
31256 {
31258 }
31260 /* Returns the TEMPLATE_TYPE_PARM in TYPE representing `auto' iff TYPE contains
31261 a use of `auto'. Returns NULL_TREE otherwise. */
31263 tree
31265 {
31269 /* For parameter packs, check the contents of the pack. */
31274 {
31275 /* The Concepts TS allows multiple autos in one type-specifier; just
31276 return the first one we find, do_auto_deduction will collect all of
31277 them. */
31281 else
31283 }
31284 else
31286 }
31288 /* Report ill-formed occurrences of auto types in ARGUMENTS. If
31289 concepts are enabled, auto is acceptable in template arguments, but
31290 only when TEMPL identifies a template class. Return TRUE if any
31291 such errors were reported. */
31293 bool
31295 {
31297 /* Only the concepts TS allows 'auto' as a type-id; it'd otherwise
31298 have already been rejected by the parser more generally. */
31301 /* If there were previous errors, nevermind. */
31305 /* If TMPL is an identifier, we're parsing and we can't tell yet
31306 whether TMPL is supposed to be a type, a function or a variable.
31307 We'll only be able to tell during template substitution, so we
31308 expect to be called again then. If concepts are enabled and we
31309 know we have a type, we're ok. */
31316 /* Quickly search for any occurrences of auto; usually there won't
31317 be any, and then we'll avoid allocating the vector. */
31325 {
31330 }
31333 }
31335 /* Recursively walk over && expressions searching for EXPR. Return a reference
31336 to that expression. */
31339 {
31343 {
31348 }
31350 }
31352 /* Convert the generic type parameters in PARM that match the types given in the
31353 range [START_IDX, END_IDX) from the current_template_parms into generic type
31354 packs. */
31356 tree
31358 {
31369 {
31370 /* Create a distinct parameter pack type from the current parm and add it
31371 to the replacement args to tsubst below into the generic function
31372 parameter. */
31386 /* Replace the current template parameter with new pack. */
31389 /* Surgically adjust the associated constraint of adjusted parameter
31390 and it's corresponding contribution to the current template
31391 requirements. */
31393 {
31396 /* Use UNKNOWN_LOCATION so write_template_args can tell the
31397 difference between this and a fold the user wrote. */
31400 TRUTH_ANDIF_EXPR);
31403 /* If there was a constraint, we also need to replace that in
31404 the template requirements, which we've already built. */
31408 }
31409 }
31415 /* If there are more levels then build up the replacement with the outer
31416 template parms. */
31420 replacement);
31423 }
31425 /* __integer_pack(N) in a pack expansion expands to a sequence of numbers from
31426 0..N-1. */
31428 void
31430 {
31433 integer_type_node,
31434 NULL_TREE),
31438 CP_BUILT_IN_INTEGER_PACK);
31439 }
31441 /* Walk the decl or type specialization table calling FN on each
31442 entry. */
31444 void
31448 {
31454 }
31456 /* Lookup the specialization of *ELT, in the decl or type
31457 specialization table. Return the SPEC that's already there, or
31458 NULL if nothing. */
31460 tree
31462 {
31472 }
31474 /* Return flags encoding whether SPEC is on the instantiation and/or
31475 specialization lists of TMPL. */
31477 unsigned
31479 {
31485 {
31488 }
31493 /* Only need to search if DECL is a partial specialization. */
31497 {
31500 }
31503 }
31505 /* Add a new specialization described by SPEC. DECL is the
31506 maybe-template decl and FLAGS is as returned from
31507 get_mergeable_specialization_flags. */
31509 void
31512 {
31515 {
31524 {
31527 }
31528 }
31531 {
31534 /* We don't distinguish different constrained partial type
31535 specializations, so there could be duplicates. Everything else
31536 must be new. */
31538 {
31544 }
31545 }
31552 {
31553 /* A partial specialization. */
31558 }
31559 }
31561 /* Set up the hash tables for template instantiations. */
31563 void
31565 {
31571 }
31573 /* Print stats about the template hash tables for -fstats. */
31575 void
31577 {
31586 }
31588 #if CHECKING_P
31592 /* Verify that type_dependent_expression_p () works correctly, even
31593 in the presence of location wrapper nodes. */
31595 static void
31597 {
31602 /* If no templates are involved, nothing is type-dependent. */
31608 /* Within a template, an unresolved name is always type-dependent. */
31611 /* Ensure it copes with NULL_TREE and errors. */
31615 /* A USING_DECL in a template should be type-dependent, even if wrapped
31616 with a location wrapper (PR c++/83799). */
31625 }
31627 /* Run all of the selftests within this file. */
31629 void
31631 {
31633 }