| blob | 6900d172806a8d7783387d729fc45af53805afd3 |
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 /* Return the template info node corresponding to T, whatever T is. */
344 tree
346 {
368 }
370 /* Returns the template nesting level of the indicated class TYPE.
372 For example, in:
373 template <class T>
374 struct A
375 {
376 template <class U>
377 struct B {};
378 };
380 A<T>::B<U> has depth two, while A<T> has depth one.
381 Both A<T>::B<int> and A<int>::B<U> have depth one, if
382 they are instantiations, not specializations.
384 This function is guaranteed to return 0 if passed NULL_TREE so
385 that, for example, `template_class_depth (current_class_type)' is
386 always safe. */
388 int
390 {
394 {
404 {
407 else
409 }
412 else
414 }
417 }
419 /* Return TRUE if NODE instantiates a template that has arguments of
420 its own, be it directly a primary template or indirectly through a
421 partial specializations. */
422 static bool
424 {
436 /* So now we know we have a specialization, but it could be a full
437 or a partial specialization. To tell which, compare the depth of
438 its template arguments with those of its context. */
447 }
449 /* Subroutine of maybe_begin_member_template_processing.
450 Returns true if processing DECL needs us to push template parms. */
452 static bool
454 {
460 }
462 /* Subroutine of maybe_begin_member_template_processing.
463 Push the template parms in PARMS, starting from LEVELS steps into the
464 chain, and ending at the beginning, since template parms are listed
465 innermost first. */
467 static void
469 {
477 current_template_parms
485 NULL);
487 {
496 {
503 /* Push the CONST_DECL. */
509 }
510 }
511 }
513 /* Restore the template parameter context for a member template, a
514 friend template defined in a class definition, or a non-template
515 member of template class. */
517 void
519 {
520 tree parms;
525 {
528 /* Disregard full specializations (c++/60999). */
531 }
534 {
539 {
542 }
545 }
547 /* Remember how many levels of template parameters we pushed so that
548 we can pop them later. */
550 }
552 /* Undo the effects of maybe_begin_member_template_processing. */
554 void
556 {
565 {
569 }
570 }
572 /* Return a new template argument vector which contains all of ARGS,
573 but has as its innermost set of arguments the EXTRA_ARGS. */
575 tree
577 {
578 tree new_args;
596 }
598 /* Like add_to_template_args, but only the outermost ARGS are added to
599 the EXTRA_ARGS. In particular, all but TMPL_ARGS_DEPTH
600 (EXTRA_ARGS) levels are added. This function is used to combine
601 the template arguments from a partial instantiation with the
602 template arguments used to attain the full instantiation from the
603 partial instantiation.
605 If ARGS is a TEMPLATE_DECL, use its parameters as args. */
607 tree
609 {
610 tree new_args;
615 {
618 }
620 /* If there are more levels of EXTRA_ARGS than there are ARGS,
621 something very fishy is going on. */
624 /* If *all* the new arguments will be the EXTRA_ARGS, just return
625 them. */
629 /* For the moment, we make ARGS look like it contains fewer levels. */
634 /* Now, we restore ARGS to its full dimensions. */
638 }
640 /* Return the N levels of innermost template arguments from the ARGS. */
642 tree
644 {
645 tree new_args;
651 /* If N is 1, just return the innermost set of template arguments. */
655 /* If we're not removing anything, just return the arguments we were
656 given. */
662 /* Make a new set of arguments, not containing the outer arguments. */
669 }
671 /* The inverse of get_innermost_template_args: Return all but the innermost
672 EXTRA_LEVELS levels of template arguments from the ARGS. */
674 static tree
676 {
677 tree new_args;
683 /* If N is 1, just return the outermost set of template arguments. */
687 /* If we're not removing anything, just return the arguments we were
688 given. */
693 /* Make a new set of arguments, not containing the inner arguments. */
700 }
702 /* We've got a template header coming up; push to a new level for storing
703 the parms. */
705 void
707 {
708 /* We use a non-tag-transparent scope here, which causes pushtag to
709 put tags in this scope, rather than in the enclosing class or
710 namespace scope. This is the right thing, since we want
711 TEMPLATE_DECLS, and not TYPE_DECLS for template classes. For a
712 global template class, push_template_decl handles putting the
713 TEMPLATE_DECL into top-level scope. For a nested template class,
714 e.g.:
716 template <class T> struct S1 {
717 template <class T> struct S2 {};
718 };
720 pushtag contains special code to insert the TEMPLATE_DECL for S2
721 at the right scope. */
727 /* Add a dummy parameter level while we process the parameter list. */
728 current_template_parms
731 current_template_parms);
732 }
734 /* This routine is called when a specialization is declared. If it is
735 invalid to declare a specialization here, an error is reported and
736 false is returned, otherwise this routine will return true. */
738 static bool
740 {
743 /* [temp.expl.spec]
745 An explicit specialization shall be declared in the namespace of
746 which the template is a member, or, for member templates, in the
747 namespace of which the enclosing class or enclosing class
748 template is a member. An explicit specialization of a member
749 function, member class or static data member of a class template
750 shall be declared in the namespace of which the class template
751 is a member. */
753 {
756 }
758 /* [temp.expl.spec]
760 In an explicit specialization declaration for a member of a class
761 template or a member template that appears in namespace scope,
762 the member template and some of its enclosing class templates may
763 remain unspecialized, except that the declaration shall not
764 explicitly specialize a class member template if its enclosing
765 class templates are not explicitly specialized as well. */
767 {
770 }
773 }
775 /* We've just seen template <>. */
777 bool
779 {
783 }
785 /* Called at then end of processing a declaration preceded by
786 template<>. */
788 void
790 {
793 }
795 /* Any template <>'s that we have seen thus far are not referring to a
796 function specialization. */
798 void
800 {
803 }
805 /* We've just seen a template header. If SPECIALIZATION is nonzero,
806 it was of the form template <>. */
808 static void
810 {
812 template_header_count++;
813 }
815 /* We're beginning an explicit instantiation. */
817 void
819 {
822 }
825 void
827 {
830 }
832 /* An explicit specialization or partial specialization of TMPL is being
833 declared. Check that the namespace in which the specialization is
834 occurring is permissible. Returns false iff it is invalid to
835 specialize TMPL in the current namespace. */
837 static bool
839 {
842 /* [tmpl.expl.spec]
844 An explicit specialization shall be declared in a namespace enclosing the
845 specialized template. An explicit specialization whose declarator-id is
846 not qualified shall be declared in the nearest enclosing namespace of the
847 template, or, if the namespace is inline (7.3.1), any namespace from its
848 enclosing namespace set. */
851 {
854 }
857 /* Same or enclosing namespace. */
859 else
860 {
861 auto_diagnostic_group d;
867 }
868 }
870 /* SPEC is an explicit instantiation. Check that it is valid to
871 perform this explicit instantiation in the current namespace. */
873 static void
875 {
876 tree ns;
878 /* DR 275: An explicit instantiation shall appear in an enclosing
879 namespace of its template. */
885 }
887 /* Returns true if TYPE is a new partial specialization that needs to be
888 set up. This may also modify TYPE to point to the correct (new or
889 existing) constrained partial specialization. */
891 static bool
893 {
894 /* An implicit instantiation of an incomplete type implies
895 the definition of a new class template.
897 template<typename T>
898 struct S;
900 template<typename T>
901 struct S<T*>;
903 Here, S<T*> is an implicit instantiation of S whose type
904 is incomplete. */
908 /* It can also be the case that TYPE is a completed specialization.
909 Continuing the previous example, suppose we also declare:
911 template<typename T>
912 requires Integral<T>
913 struct S<T*>;
915 Here, S<T*> refers to the specialization S<T*> defined
916 above. However, we need to differentiate definitions because
917 we intend to define a new partial specialization. In this case,
918 we rely on the fact that the constraints are different for
919 this declaration than that above.
921 Note that we also get here for injected class names and
922 late-parsed template definitions. We must ensure that we
923 do not create new type declarations for those cases. */
925 {
929 /* If there are no template parameters, this cannot be a new
930 partial template specialization? */
934 /* The injected-class-name is not a new partial specialization. */
938 /* If the constraints are not the same as those of the primary
939 then, we can probably create a new specialization. */
943 {
947 }
949 /* Also, if there's a pre-existing specialization with matching
950 constraints, then this also isn't new. */
953 {
959 {
962 }
964 }
966 /* Create a new type node (and corresponding type decl)
967 for the newly declared specialization. */
972 /* We only need a separate type node for storing the definition of this
973 partial specialization; uses of S<T*> are unconstrained, so all are
974 equivalent. So keep TYPE_CANONICAL the same. */
977 /* Build the corresponding type decl. */
989 }
992 }
994 /* The TYPE is being declared. If it is a template type, that means it
995 is a partial specialization. Do appropriate error-checking. */
997 tree
999 {
1000 tree context;
1005 /* A lambda that appears in specialization context is not itself a
1006 specialization. */
1010 /* An injected-class-name is not a specialization. */
1015 {
1019 }
1024 {
1030 else
1033 }
1035 {
1036 /* This is for ordinary explicit specialization and partial
1037 specialization of a template class such as:
1039 template <> class C<int>;
1041 or:
1043 template <class T> class C<T*>;
1045 Make sure that `C<int>' and `C<T*>' are implicit instantiations. */
1048 {
1055 {
1060 }
1061 }
1067 /* Trying to define a specialization either without a template<> header
1068 or in an inappropriate place. We've already given an error, so just
1069 bail now so we don't actually define the specialization. */
1071 }
1077 {
1078 /* This is for an explicit specialization of member class
1079 template according to [temp.expl.spec/18]:
1081 template <> template <class U> class C<int>::D;
1083 The context `C<int>' must be an implicit instantiation.
1084 Otherwise this is just a member class template declared
1085 earlier like:
1087 template <> class C<int> { template <class U> class D; };
1088 template <> template <class U> class C<int>::D;
1090 In the first case, `C<int>::D' is a specialization of `C<T>::D'
1091 while in the second case, `C<int>::D' is a primary template
1092 and `C<T>::D' may not exist. */
1096 {
1097 tree t;
1102 {
1105 type))
1108 }
1110 /* Check for invalid specialization after instantiation:
1112 template <> template <> class C<int>::D<int>;
1113 template <> template <class U> class C<int>::D; */
1117 {
1121 {
1122 /* We already have a full specialization of this partial
1123 instantiation, or a full specialization has been
1124 looked up but not instantiated. Reassign it to the
1125 new member specialization template. */
1126 spec_entry elt;
1139 spec_entry **slot
1144 }
1145 else
1146 /* But if we've had an implicit instantiation, that's a
1147 problem ([temp.expl.spec]/6). */
1150 }
1152 /* Mark TYPE as a specialization. And as a result, we only
1153 have one level of template argument for the innermost
1154 class template. */
1159 }
1160 }
1162 {
1163 /* Someday C++0x may allow for enum template specialization. */
1168 else
1169 {
1172 }
1173 }
1176 }
1178 /* Make sure ARGS doesn't use any inappropriate typedefs; we should have
1179 gone through coerce_template_parms by now. */
1181 static void
1183 {
1185 {
1194 /* Allow typedefs on the type of a non-type argument, since a
1196 else
1198 }
1199 }
1201 static void
1203 {
1208 }
1210 /* Retrieve the specialization (in the sense of [temp.spec] - a
1211 specialization is either an instantiation or an explicit
1212 specialization) of TMPL for the given template ARGS. If there is
1213 no such specialization, return NULL_TREE. The ARGS are a vector of
1214 arguments, or a vector of vectors of arguments, in the case of
1215 templates with more than one level of parameters.
1217 If TMPL is a type template and CLASS_SPECIALIZATIONS_P is true,
1218 then we search for a partial specialization matching ARGS. This
1219 parameter is ignored if TMPL is not a class template.
1221 We can also look up a FIELD_DECL, if it is a lambda capture pack; the
1222 result is a NONTYPE_ARGUMENT_PACK. */
1224 static tree
1226 {
1236 /* There should be as many levels of arguments as there are
1237 levels of parameters. */
1246 /* Lambda functions in templates aren't instantiated normally, but through
1247 tsubst_lambda_expr. */
1251 spec_entry elt;
1259 else
1268 }
1270 /* Like retrieve_specialization, but for local declarations. */
1272 tree
1274 {
1280 }
1282 /* Returns nonzero iff DECL is a specialization of TMPL. */
1284 int
1286 {
1287 tree t;
1290 {
1296 }
1297 else
1298 {
1307 }
1310 }
1312 /* Returns nonzero iff DECL is a specialization of friend declaration
1313 FRIEND_DECL according to [temp.friend]. */
1315 bool
1317 {
1324 /* For [temp.friend/6] when FRIEND_DECL is an ordinary member function
1325 of a template class, we want to check if DECL is a specialization
1326 if this. */
1331 {
1332 /* We want a TEMPLATE_DECL for `is_specialization_of'. */
1335 }
1340 /* There is nothing to do if this is not a template friend. */
1347 /* [temp.friend/6]
1348 A member of a class template may be declared to be a friend of a
1349 non-template class. In this case, the corresponding member of
1350 every specialization of the class template is a friend of the
1351 class granting friendship.
1353 For example, given a template friend declaration
1355 template <class T> friend void A<T>::f();
1357 the member function below is considered a friend
1359 template <> struct A<int> {
1360 void f();
1361 };
1363 For this type of template friend, TEMPLATE_DEPTH below will be
1364 nonzero. To determine if DECL is a friend of FRIEND, we first
1365 check if the enclosing class is a specialization of another. */
1372 {
1373 /* Next, we check the members themselves. In order to handle
1374 a few tricky cases, such as when FRIEND_DECL's are
1376 template <class T> friend void A<T>::g(T t);
1377 template <class T> template <T t> friend void A<T>::h();
1379 and DECL's are
1381 void A<int>::g(int);
1382 template <int> void A<int>::h();
1384 we need to figure out ARGS, the template arguments from
1385 the context of DECL. This is required for template substitution
1386 of `T' in the function parameter of `g' and template parameter
1387 of `h' in the above examples. Here ARGS corresponds to `int'. */
1394 {
1396 {
1399 else
1401 current_depth++;
1402 }
1404 }
1407 {
1409 tree friend_type;
1410 tree decl_type;
1411 tree friend_args_type;
1412 tree decl_args_type;
1414 /* Make sure that both DECL and FRIEND_DECL are templates or
1415 non-templates. */
1421 {
1422 /* If both are templates, check template parameter list. */
1423 tree friend_parms
1428 friend_parms))
1432 }
1433 else
1441 /* Check if return types match. */
1445 /* Check if function parameter types match, ignoring the
1446 `this' parameter. */
1455 }
1456 else
1457 {
1458 /* DECL is a TYPE_DECL */
1462 /* Make sure that both DECL and FRIEND_DECL are templates or
1463 non-templates. */
1464 is_template
1471 {
1472 tree friend_parms;
1473 /* If both are templates, check the name of the two
1474 TEMPLATE_DECL's first because is_friend didn't. */
1479 /* Now check template parameter list. */
1480 friend_parms
1483 return comp_template_parms
1485 friend_parms);
1486 }
1487 else
1490 }
1491 }
1493 }
1495 /* Register the specialization SPEC as a specialization of TMPL with
1496 the indicated ARGS. IS_FRIEND indicates whether the specialization
1497 is actually just a friend declaration. ATTRLIST is the list of
1498 attributes that the specialization is declared with or NULL when
1499 it isn't. Returns SPEC, or an equivalent prior declaration, if
1500 available.
1502 We also store instantiations of field packs in the hash table, even
1503 though they are not themselves templates, to make lookup easier. */
1505 static tree
1507 hashval_t hash)
1508 {
1509 tree fn;
1515 spec_entry elt;
1526 else
1529 /* We can sometimes try to re-register a specialization that we've
1530 already got. In particular, regenerate_decl_from_template calls
1531 duplicate_decls which will update the specialization list. But,
1532 we'll still get called again here anyhow. It's more convenient
1533 to simply allow this than to try to prevent it. */
1537 {
1539 {
1542 {
1544 fn);
1546 }
1547 else
1548 {
1549 tree clone;
1550 /* This situation should occur only if the first
1551 specialization is an implicit instantiation, the
1552 second is an explicit specialization, and the
1553 implicit instantiation has not yet been used. That
1554 situation can occur if we have implicitly
1555 instantiated a member function and then specialized
1556 it later.
1558 We can also wind up here if a friend declaration that
1559 looked like an instantiation turns out to be a
1560 specialization:
1562 template <class T> void foo(T);
1563 class S { friend void foo<>(int) };
1564 template <> void foo(int);
1566 We transform the existing DECL in place so that any
1567 pointers to it become pointers to the updated
1568 declaration.
1570 If there was a definition for the template, but not
1571 for the specialization, we want this to look as if
1572 there were no definition, and vice versa. */
1576 /* The call to duplicate_decls will have applied
1577 [temp.expl.spec]:
1579 An explicit specialization of a function template
1580 is inline only if it is explicitly declared to be,
1581 and independently of whether its function template
1582 is.
1584 to the primary function; now copy the inline bits to
1585 the various clones. */
1587 {
1594 }
1598 }
1599 }
1601 {
1604 /* We've already complained in duplicate_decls. */
1608 /* Dup decl failed, but this is a new definition. Set the
1609 line number so any errors match this new
1610 definition. */
1614 }
1615 }
1619 /* A specialization must be declared in the same namespace as the
1620 template it is specializing. */
1633 /* If TMPL is a forward declaration of a template function, keep a list
1634 of all specializations in case we need to reassign them to a friend
1635 template later in tsubst_friend_function.
1637 Also keep a list of all variable template instantiations so that
1638 process_partial_specialization can check whether a later partial
1639 specialization would have used it. */
1644 }
1646 /* Restricts tree and type comparisons. */
1650 /* Whether we are comparing template arguments during partial ordering
1651 (and therefore want the comparison to look through dependent alias
1652 template specializations). */
1656 /* Returns true iff two spec_entry nodes are equivalent. */
1658 bool
1660 {
1669 /* tmpl could be a FIELD_DECL for a capture pack. */
1673 {
1674 /* Partial specializations of a variable template can be distinguished by
1675 constraints. */
1679 }
1685 }
1687 /* Returns a hash for a template TMPL and template arguments ARGS. */
1689 static hashval_t
1691 {
1694 }
1696 hashval_t
1698 {
1703 }
1705 /* Returns a hash for a spec_entry node based on the TMPL and ARGS members,
1706 ignoring SPEC. */
1708 hashval_t
1710 {
1712 }
1714 /* Recursively calculate a hash value for a template argument ARG, for use
1715 in the hash tables of template specializations. We must be
1716 careful to (at least) skip the same entities template_args_equal
1717 does. */
1719 hashval_t
1721 {
1726 /* Strip nop-like things, but not the same as STRIP_NOPS. */
1737 {
1739 /* Getting here with an ARGUMENT_PACK_SELECT means we're probably
1740 preserving it in a hash table, which is bad because it will change
1741 meaning when gen_elem_of_pack_expansion_instantiation changes the
1742 ARGUMENT_PACK_SELECT_INDEX. */
1776 {
1779 {
1782 }
1784 }
1788 {
1791 }
1802 val = iterative_hash_template_arg
1814 val);
1816 val);
1825 /* [temp.over.link] Two lambda-expressions are never considered
1826 equivalent.
1828 So just hash the closure type. */
1839 /* Now hash operands as usual. */
1843 {
1846 {
1850 }
1852 call_expr_arg_iterator ai;
1857 }
1861 }
1865 {
1868 {
1869 // We want an alias specialization that survived strip_typedefs
1870 // to hash differently from its TYPE_CANONICAL, to avoid hash
1871 // collisions that compare as different in template_args_equal.
1872 // These could be dependent specializations that strip_typedefs
1873 // left alone, or untouched specializations because
1874 // coerce_template_parms returns the unconverted template
1875 // arguments if it sees incomplete argument packs.
1878 }
1881 {
1888 {
1889 /* Hash the components that are relevant to TYPENAME_TYPE
1890 equivalence as determined by structural_comptypes. We
1891 can only coherently do this when comparing_specializations
1892 is set, because otherwise structural_comptypes tries
1893 resolving TYPENAME_TYPE via the current instantiation. */
1898 }
1905 {
1908 }
1910 }
1923 }
1924 }
1926 /* Unregister the specialization SPEC as a specialization of TMPL.
1927 Replace it with NEW_SPEC, if NEW_SPEC is non-NULL. Returns true
1928 if the SPEC was listed as a specialization of TMPL.
1930 Note that SPEC has been ggc_freed, so we can't look inside it. */
1932 bool
1934 {
1936 spec_entry elt;
1944 {
1949 }
1952 }
1954 /* Like register_specialization, but for local declarations. We are
1955 registering SPEC, an instantiation of TMPL. */
1957 void
1959 {
1962 }
1964 /* Registers T as a specialization of itself. This is used to preserve
1965 the references to already-parsed parameters when instantiating
1966 postconditions. */
1968 void
1970 {
1972 }
1974 /* TYPE is a class type. Returns true if TYPE is an explicitly
1975 specialized class. */
1977 bool
1979 {
1983 }
1985 /* Print the list of functions at FNS, going through all the overloads
1986 for each element of the list. Alternatively, FNS cannot be a
1987 TREE_LIST, in which case it will be printed together with all the
1988 overloads.
1990 MORE and *STR should respectively be FALSE and NULL when the function
1991 is called from the outside. They are used internally on recursive
1992 calls. print_candidates manages the two parameters and leaves NULL
1993 in *STR when it ends. */
1995 static void
1997 {
2001 else
2003 {
2009 {
2012 else
2015 }
2017 }
2018 }
2020 /* Print the list of candidate FNS in an error message. FNS can also
2021 be a TREE_LIST of non-functions in the case of an ambiguous lookup. */
2023 void
2025 {
2029 }
2031 /* Get a (possibly) constrained template declaration for the
2032 purpose of ordering candidates. */
2033 static tree
2035 {
2041 }
2043 /* Among candidates having the same signature, return the
2044 most constrained or NULL_TREE if there is no best candidate.
2045 If the signatures of candidates vary (e.g., template
2046 specialization vs. member function), then there can be no
2047 most constrained.
2049 Note that we don't compare constraints on the functions
2050 themselves, but rather those of their templates. */
2051 static tree
2053 {
2054 // Try to find the best candidate in a first pass.
2057 {
2064 }
2066 // Verify that the champ is better than previous candidates.
2071 }
2074 }
2077 /* Returns the template (one of the functions given by TEMPLATE_ID)
2078 which can be specialized to match the indicated DECL with the
2079 explicit template args given in TEMPLATE_ID. The DECL may be
2080 NULL_TREE if none is available. In that case, the functions in
2081 TEMPLATE_ID are non-members.
2083 If NEED_MEMBER_TEMPLATE is nonzero the function is known to be a
2084 specialization of a member template.
2086 The TEMPLATE_COUNT is the number of references to qualifying
2087 template classes that appeared in the name of the function. See
2088 check_explicit_specialization for a more accurate description.
2090 TSK indicates what kind of template declaration (if any) is being
2091 declared. TSK_TEMPLATE indicates that the declaration given by
2092 DECL, though a FUNCTION_DECL, has template parameters, and is
2093 therefore a template function.
2095 The template args (those explicitly specified and those deduced)
2096 are output in a newly created vector *TARGS_OUT.
2098 If it is impossible to determine the result, an error message is
2099 issued. The error_mark_node is returned to indicate failure. */
2101 static tree
2103 tree decl,
2107 tmpl_spec_kind tsk)
2108 {
2109 tree fns;
2110 tree targs;
2111 tree explicit_targs;
2114 /* A TREE_LIST of templates of which DECL may be a specialization.
2115 The TREE_VALUE of each node is a TEMPLATE_DECL. The
2116 corresponding TREE_PURPOSE is the set of template arguments that,
2117 when used to instantiate the template, would produce a function
2118 with the signature of DECL. */
2128 /* We shouldn't be specializing a member template of an
2129 unspecialized class template; we already gave an error in
2130 check_specialization_scope, now avoid crashing. */
2134 {
2137 }
2145 /* Check for baselinks. */
2150 {
2154 }
2156 {
2159 }
2161 /* Count the number of template headers specified for this
2162 specialization. */
2173 {
2176 tf_warning_or_error);
2180 }
2182 {
2186 {
2187 tree decl_arg_types;
2188 tree fn_arg_types;
2190 /* In case of explicit specialization, we need to check if
2191 the number of template headers appearing in the specialization
2192 is correct. This is usually done in check_explicit_specialization,
2193 but the check done there cannot be exhaustive when specializing
2194 member functions. Consider the following code:
2196 template <> void A<int>::f(int);
2197 template <> template <> void A<int>::f(int);
2199 Assuming that A<int> is not itself an explicit specialization
2200 already, the first line specializes "f" which is a non-template
2201 member function, whilst the second line specializes "f" which
2202 is a template member function. So both lines are syntactically
2203 correct, and check_explicit_specialization does not reject
2204 them.
2206 Here, we can do better, as we are matching the specialization
2207 against the declarations. We count the number of template
2208 headers, and we check if they match TEMPLATE_COUNT + 1
2209 (TEMPLATE_COUNT is the number of qualifying template classes,
2210 plus there must be another header for the member template
2211 itself).
2213 Notice that if header_count is zero, this is not a
2214 specialization but rather a template instantiation, so there
2215 is no check we can perform here. */
2217 {
2220 }
2222 /* Check that the number of template arguments at the
2223 innermost level for DECL is the same as for FN. */
2231 /* DECL might be a specialization of FN. */
2235 /* For a non-static member function, we need to make sure
2236 that the const qualification is the same. Since
2237 get_bindings does not try to merge the "this" parameter,
2238 we must do the comparison explicitly. */
2240 {
2245 /* And the ref-qualification. */
2249 }
2251 /* Skip the "this" parameter and, for constructors of
2252 classes with virtual bases, the VTT parameter. A
2253 full specialization of a constructor will have a VTT
2254 parameter, but a template never will. */
2255 decl_arg_types
2257 fn_arg_types
2260 /* Function templates cannot be specializations; there are
2261 no partial specializations of functions. Therefore, if
2262 the type of DECL does not match FN, there is no
2263 match.
2265 Note that it should never be the case that we have both
2266 candidates added here, and for regular member functions
2267 below. */
2269 {
2271 current_template_parms))
2284 {
2285 /* C++20 CA104: Substitute directly into the
2286 constraint-expression. */
2292 }
2296 }
2298 /* See whether this function might be a specialization of this
2299 template. Suppress access control because we might be trying
2300 to make this specialization a friend, and we have already done
2301 access control for the declaration of the specialization. */
2307 /* We cannot deduce template arguments that when used to
2308 specialize TMPL will produce DECL. */
2312 /* We deduced something involving 'auto', which isn't a valid
2313 template argument. */
2316 /* Save this template, and the arguments deduced. */
2318 }
2320 /* FN is an ordinary member function, and we need a
2321 specialization of a member template. */
2322 ;
2324 /* We can get IDENTIFIER_NODEs here in certain erroneous
2325 cases. */
2326 ;
2328 /* This is just an ordinary non-member function. Nothing can
2329 be a specialization of that. */
2330 ;
2332 /* Cannot specialize functions that are created implicitly. */
2333 ;
2334 else
2335 {
2336 tree decl_arg_types;
2338 /* This is an ordinary member function. However, since
2339 we're here, we can assume its enclosing class is a
2340 template class. For example,
2342 template <typename T> struct S { void f(); };
2343 template <> void S<int>::f() {}
2345 Here, S<int>::f is a non-template, but S<int> is a
2346 template class. If FN has the same type as DECL, we
2347 might be in business. */
2350 /* Its enclosing class is an explicit specialization
2351 of a template class. This is not a candidate. */
2356 /* The return types differ. */
2359 /* Adjust the type of DECL in case FN is a static member. */
2366 decl_arg_types))
2374 // If the deduced arguments do not satisfy the constraints,
2375 // this is not a candidate.
2379 // Add the candidate.
2381 }
2382 }
2385 {
2386 /* We have:
2388 [temp.expl.spec]
2390 It is possible for a specialization with a given function
2391 signature to be instantiated from more than one function
2392 template. In such cases, explicit specification of the
2393 template arguments must be used to uniquely identify the
2394 function template specialization being specialized.
2396 Note that here, there's no suggestion that we're supposed to
2397 determine which of the candidate templates is most
2398 specialized. However, we, also have:
2400 [temp.func.order]
2402 Partial ordering of overloaded function template
2403 declarations is used in the following contexts to select
2404 the function template to which a function template
2405 specialization refers:
2407 -- when an explicit specialization refers to a function
2408 template.
2410 So, we do use the partial ordering rules, at least for now.
2411 This extension can only serve to make invalid programs valid,
2412 so it's safe. And, there is strong anecdotal evidence that
2413 the committee intended the partial ordering rules to apply;
2414 the EDG front end has that behavior, and John Spicer claims
2415 that the committee simply forgot to delete the wording in
2416 [temp.expl.spec]. */
2419 {
2422 }
2423 }
2425 // Concepts allows multiple declarations of member functions
2426 // with the same signature. Like above, we need to rely on
2427 // on the partial ordering of those candidates to determine which
2428 // is the best.
2430 {
2432 {
2435 }
2436 }
2439 {
2444 "saw %d %<template<>%>, need %d for "
2449 }
2453 {
2459 }
2461 /* We have one, and exactly one, match. */
2463 {
2467 /* Propagate the candidate's constraints to the declaration. */
2471 /* DECL is a re-declaration or partial instantiation of a template
2472 function. */
2475 /* It was a specialization of an ordinary member function in a
2476 template class. */
2478 }
2480 /* It was a specialization of a template. */
2484 /* Propagate the template's constraints to the declaration. */
2489 }
2491 /* Returns a chain of parameter types, exactly like the SPEC_TYPES,
2492 but with the default argument values filled in from those in the
2493 TMPL_TYPES. */
2495 static tree
2497 tree tmpl_types)
2498 {
2499 tree new_spec_types;
2507 /* Substitute into the rest of the list. */
2508 new_spec_types =
2512 /* Add the default argument for this parameter. */
2515 new_spec_types);
2516 }
2518 /* DECL is an explicit specialization. Replicate default arguments
2519 from the template it specializes. (That way, code like:
2521 template <class T> void f(T = 3);
2522 template <> void f(double);
2523 void g () { f (); }
2525 works, as required.) An alternative approach would be to look up
2526 the correct default arguments at the call-site, but this approach
2527 is consistent with how implicit instantiations are handled. */
2529 static void
2531 {
2532 tree tmpl;
2533 tree spec_types;
2534 tree tmpl_types;
2535 tree new_spec_types;
2536 tree old_type;
2537 tree new_type;
2538 tree t;
2543 /* See if there's anything we need to do. */
2556 {
2557 /* Remove the this pointer, but remember the object's type for
2558 CV quals. */
2564 {
2565 /* DECL may contain more parameters than TMPL due to the extra
2566 in-charge parameter in constructors and destructors. */
2569 }
2571 {
2574 }
2575 }
2577 /* Compute the merged default arguments. */
2578 new_spec_types =
2581 /* Compute the new FUNCTION_TYPE. */
2583 {
2587 new_spec_types);
2590 /* Put the in-charge parameter back. */
2593 new_spec_types);
2597 new_spec_types);
2598 }
2599 else
2601 new_spec_types);
2607 }
2609 /* Return the number of template headers we expect to see for a definition
2610 or specialization of CTYPE or one of its non-template members. */
2612 int
2614 {
2618 {
2619 /* You're supposed to have one `template <...>' for every
2620 template class, but you don't need one for a full
2621 specialization. For example:
2623 template <class T> struct S{};
2624 template <> struct S<int> { void f(); };
2625 void S<int>::f () {}
2627 is correct; there shouldn't be a `template <>' for the
2628 definition of `S<int>::f'. */
2630 /* If CTYPE does not have template information of any
2631 kind, then it is not a template, nor is it nested
2632 within a template. */
2640 }
2643 }
2645 /* Do a simple sanity check on the template headers that precede the
2646 variable declaration DECL. */
2648 void
2650 {
2655 {
2658 "variable templates only available with "
2661 // Namespace-scope variable templates should have a template header.
2663 }
2665 {
2666 auto_diagnostic_group d;
2668 "too many template headers for %qD "
2674 "members of an explicitly specialized class are defined "
2676 }
2677 }
2679 /* An explicit specialization whose declarator-id or class-head-name is not
2680 qualified shall be declared in the nearest enclosing namespace of the
2681 template, or, if the namespace is inline (7.3.1), any namespace from its
2682 enclosing namespace set.
2684 If the name declared in the explicit instantiation is an unqualified name,
2685 the explicit instantiation shall appear in the namespace where its template
2686 is declared or, if that namespace is inline (7.3.1), any namespace from its
2687 enclosing namespace set. */
2689 void
2691 {
2696 {
2702 /* This was allowed in C++98, so only pedwarn. */
2704 "outside its namespace must use a nested-name-"
2706 }
2707 }
2709 /* Warn for a template specialization SPEC that is missing some of a set
2710 of function or type attributes that the template TEMPL is declared with.
2711 ATTRLIST is a list of additional attributes that SPEC should be taken
2712 to ultimately be declared with. */
2714 static void
2716 {
2720 /* Avoid warning if the difference between the primary and
2721 the specialization is not in one of the attributes below. */
2725 };
2727 /* Put together a list of the black listed attributes that the primary
2728 template is declared with that the specialization is not, in case
2729 it's not apparent from the most recent declaration of the primary. */
2730 pretty_printer str;
2737 auto_diagnostic_group d;
2740 spec))
2746 }
2748 /* Check to see if the function just declared, as indicated in
2749 DECLARATOR, and in DECL, is a specialization of a function
2750 template. We may also discover that the declaration is an explicit
2751 instantiation at this point.
2753 Returns DECL, or an equivalent declaration that should be used
2754 instead if all goes well. Issues an error message if something is
2755 amiss. Returns error_mark_node if the error is not easily
2756 recoverable.
2758 FLAGS is a bitmask consisting of the following flags:
2760 2: The function has a definition.
2761 4: The function is a friend.
2763 The TEMPLATE_COUNT is the number of references to qualifying
2764 template classes that appeared in the name of the function. For
2765 example, in
2767 template <class T> struct S { void f(); };
2768 void S<int>::f();
2770 the TEMPLATE_COUNT would be 1. However, explicitly specialized
2771 classes are not counted in the TEMPLATE_COUNT, so that in
2773 template <class T> struct S {};
2774 template <> struct S<int> { void f(); }
2775 template <> void S<int>::f();
2777 the TEMPLATE_COUNT would be 0. (Note that this declaration is
2778 invalid; there should be no template <>.)
2780 If the function is a specialization, it is marked as such via
2781 DECL_TEMPLATE_SPECIALIZATION. Furthermore, its DECL_TEMPLATE_INFO
2782 is set up correctly, and it is added to the list of specializations
2783 for that template. */
2785 tree
2787 tree decl,
2790 tree attrlist)
2791 {
2800 tmpl_spec_kind tsk;
2803 {
2806 else
2808 }
2809 else
2813 {
2816 {
2819 }
2823 {
2825 /* This could be something like:
2827 template <class T> void f(T);
2828 class S { friend void f<>(int); } */
2830 else
2831 {
2832 /* This case handles bogus declarations like template <>
2833 template <class T> void f<int>(); */
2837 declarator);
2839 }
2840 }
2844 /* The error has already been reported in
2845 check_specialization_scope. */
2851 /* Fall through. */
2864 decl);
2867 else
2871 /* Fall through. */
2877 /* In cases like template<> constexpr bool v = true;
2878 We'll give an error in check_template_variable. */
2884 else
2890 {
2891 /* This case handles bogus declarations like template <>
2892 template <class T> void f<int>(); */
2897 declarator);
2899 {
2900 /* Partial specialization of variable template. */
2904 }
2907 "non-type partial specialization %qE "
2909 else
2911 "non-class, non-variable partial specialization %qE "
2914 ok:;
2915 }
2918 /* This is a specialization of a member template, without
2919 specialization the containing class. Something like:
2921 template <class T> struct S {
2922 template <class U> void f (U);
2923 };
2924 template <> template <class U> void S<int>::f(U) {}
2926 That's a specialization -- but of the entire template. */
2932 }
2935 /* This doesn't apply to variable templates. */
2937 {
2941 {
2945 }
2946 }
2949 {
2955 /* Make sure that the declarator is a TEMPLATE_ID_EXPR. */
2957 {
2958 tree fns;
2963 else
2964 {
2965 /* If there is no class context, the explicit instantiation
2966 must be at namespace scope. */
2969 /* Find the namespace binding, using the declaration
2970 context. */
2974 {
2975 /* If lookup fails, look for a friend declaration so we can
2976 give a better diagnostic. */
2977 fns = (lookup_qualified_name
2982 }
2985 {
2988 }
2989 }
2992 }
2998 {
3000 /* A specialization in class scope. This is invalid,
3001 but the error will already have been flagged by
3002 check_specialization_scope. */
3004 else
3005 {
3006 /* It's not valid to write an explicit instantiation in
3007 class scope, e.g.:
3009 class C { template void f(); }
3011 This case is caught by the parser. However, on
3012 something like:
3014 template class C { void f(); };
3016 (which is invalid) we can get here. The error will be
3017 issued later. */
3018 ;
3019 }
3022 }
3025 {
3026 // We'll match variable templates in start_decl.
3030 /* Find the list of functions in ctype that have the same
3031 name as the declared function. */
3035 {
3039 {
3040 /* From [temp.expl.spec]:
3042 If such an explicit specialization for the member
3043 of a class template names an implicitly-declared
3044 special member function (clause _special_), the
3045 program is ill-formed.
3047 Similar language is found in [temp.explicit]. */
3050 }
3053 }
3055 /* For a type-conversion operator, We might be looking for
3056 `operator int' which will be a specialization of
3057 `operator T'. Grab all the conversion operators, and
3058 then select from them. */
3063 {
3066 }
3067 else
3069 }
3071 /* Figure out what exactly is being specialized at this point.
3072 Note that for an explicit instantiation, even one for a
3073 member function, we cannot tell a priori whether the
3074 instantiation is for a member template, or just a member
3075 function of a template class. Even if a member template is
3076 being instantiated, the member template arguments may be
3077 elided if they can be deduced from the rest of the
3078 declaration. */
3081 member_specialization,
3082 template_count,
3083 tsk);
3086 /* We couldn't figure out what this declaration was
3087 specializing. */
3089 else
3090 {
3092 {
3093 auto_diagnostic_group d;
3095 "friend declaration %qD is not visible to "
3099 }
3108 {
3109 /* We don't set DECL_EXPLICIT_INSTANTIATION here; that
3110 is done by do_decl_instantiation later. */
3116 {
3117 /* If TMPL is not the most general template (for
3118 example, if TMPL is a friend template that is
3119 injected into namespace scope), then there will
3120 be too many levels of TARGS. Remove some of them
3121 here. */
3123 tree new_targs;
3130 }
3133 }
3135 /* If we thought that the DECL was a member function, but it
3136 turns out to be specializing a static member function,
3137 make DECL a static member function as well. */
3143 /* If this is a specialization of a member template of a
3144 template class, we want to return the TEMPLATE_DECL, not
3145 the specialization of it. */
3147 {
3152 {
3153 tree parm;
3157 /* We want to use the argument list specified in the
3158 definition, not in the original declaration. */
3163 }
3168 }
3170 /* Set up the DECL_TEMPLATE_INFO for DECL. */
3176 /* Inherit default function arguments from the template
3177 DECL is specializing. */
3181 /* This specialization has the same protection as the
3182 template it specializes. */
3186 /* 7.1.1-1 [dcl.stc]
3188 A storage-class-specifier shall not be specified in an
3189 explicit specialization...
3191 The parser rejects these, so unless action is taken here,
3192 explicit function specializations will always appear with
3193 global linkage.
3195 The action recommended by the C++ CWG in response to C++
3196 defect report 605 is to make the storage class and linkage
3197 of the explicit specialization match the templated function:
3199 http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#605
3200 */
3202 {
3206 /* A concept cannot be specialized. */
3208 {
3210 gen_tmpl);
3212 }
3214 /* This specialization has the same linkage and visibility as
3215 the function template it specializes. */
3218 {
3221 }
3224 {
3227 }
3228 }
3230 /* If DECL is a friend declaration, declared using an
3231 unqualified name, the namespace associated with DECL may
3232 have been set incorrectly. For example, in:
3234 template <typename T> void f(T);
3235 namespace N {
3236 struct S { friend void f<int>(int); }
3237 }
3239 we will have set the DECL_CONTEXT for the friend
3240 declaration to N, rather than to the global namespace. */
3245 /* This is not really a declaration of a specialization.
3246 It's just the name of an instantiation. But, it's not
3247 a request for an instantiation, either. */
3250 /* A specialization is not necessarily COMDAT. */
3256 /* If this is a full specialization, register it so that we can find
3257 it again. Partial specializations will be registered in
3258 process_partial_specialization. */
3260 {
3265 }
3267 /* If this is a specialization, splice any contracts that may have
3268 been inherited from the template, removing them. */
3272 /* A 'structor should already have clones. */
3278 }
3279 }
3282 }
3284 /* Returns 1 iff PARMS1 and PARMS2 are identical sets of template
3285 parameters. These are represented in the same format used for
3286 DECL_TEMPLATE_PARMS. */
3288 int
3290 {
3305 {
3309 /* If either of the template parameters are invalid, assume
3310 they match for the sake of error recovery. */
3323 }
3326 }
3328 /* Returns true if two template parameters are declared with
3329 equivalent constraints. */
3331 static bool
3333 {
3341 }
3343 /* Returns true when two template parameters are equivalent. */
3345 static bool
3347 {
3351 /* If either of the template parameters are invalid, assume
3352 they match for the sake of error recovery. */
3356 /* ... they declare parameters of the same kind. */
3360 /* ... one parameter was introduced by a parameter declaration, then
3361 both are. This case arises as a result of eagerly rewriting declarations
3362 during parsing. */
3367 /* ... if either declares a pack, they both do. */
3372 {
3373 /* ... if they declare non-type parameters, the types are equivalent. */
3376 }
3378 {
3379 /* ... if they declare template template parameters, their template
3380 parameter lists are equivalent. */
3383 }
3385 /* ... if they are declared with a qualified-concept name, they both
3386 are, and those names are equivalent. */
3388 }
3390 /* Returns true if two template parameters lists are equivalent.
3391 Two template parameter lists are equivalent if they have the
3392 same length and their corresponding parameters are equivalent.
3394 PARMS1 and PARMS2 are TREE_LISTs containing TREE_VECs: the
3395 data structure returned by DECL_TEMPLATE_PARMS.
3397 This is generally the same implementation as comp_template_parms
3398 except that it also the concept names and arguments used to
3399 introduce parameters. */
3401 static bool
3403 {
3414 {
3419 }
3422 }
3424 /* Return true if the requires-clause of the template parameter lists are
3425 equivalent and false otherwise. */
3426 static bool
3428 {
3436 }
3438 /* Returns true if two template heads are equivalent. 17.6.6.1p6:
3439 Two template heads are equivalent if their template parameter
3440 lists are equivalent and their requires clauses are equivalent.
3442 In pre-C++20, this is equivalent to calling comp_template_parms
3443 for the template parameters of TMPL1 and TMPL2. */
3445 bool
3447 {
3451 /* Don't change the matching rules for pre-C++20. */
3455 /* ... have the same number of template parameters, and their
3456 corresponding parameters are equivalent. */
3460 /* ... if either has a requires-clause, they both do and their
3461 corresponding constraint-expressions are equivalent. */
3463 }
3465 /* Determine whether PARM is a parameter pack. */
3467 bool
3469 {
3470 /* Determine if we have a non-type template parameter pack. */
3477 /* If this is a list of template parameters, we could get a
3478 TYPE_DECL or a TEMPLATE_DECL. */
3482 /* Otherwise it must be a type template parameter. */
3486 }
3488 /* Determine if T is a function parameter pack. */
3490 bool
3492 {
3496 }
3498 /* Return the function template declaration of PRIMARY_FUNC_TMPL_INST.
3499 PRIMARY_FUNC_TMPL_INST is a primary function template instantiation. */
3501 tree
3503 {
3510 }
3512 /* Return true iff the function parameter PARAM_DECL was expanded
3513 from the function parameter pack PACK. */
3515 bool
3517 {
3522 /* The parameter pack and its pack arguments have the same
3523 DECL_PARM_INDEX. */
3525 }
3527 /* Determine whether ARGS describes a variadic template args list,
3528 i.e., one that is terminated by a template argument pack. */
3530 static bool
3532 {
3534 tree last_parm;
3548 }
3550 /* Generate a new name for the parameter pack name NAME (an
3551 IDENTIFIER_NODE) that incorporates its */
3553 static tree
3555 {
3556 /* Munge the name to include the parameter index. */
3557 #define NUMBUF_LEN 128
3571 }
3573 /* Return true if T is a primary function, class or alias template
3574 specialization, not including the template pattern. */
3576 bool
3578 {
3594 }
3596 /* Return true if PARM is a template template parameter. */
3598 bool
3600 {
3602 }
3604 /* Return true iff PARM is a DECL representing a type template
3605 parameter. */
3607 bool
3609 {
3614 }
3616 /* Return the template parameters of T if T is a
3617 primary template instantiation, NULL otherwise. */
3619 tree
3621 {
3626 parms = INNERMOST_TEMPLATE_PARMS
3630 }
3632 /* Returns the template arguments of T if T is a template instantiation,
3633 NULL otherwise. */
3635 tree
3637 {
3645 }
3647 /* Return the argument pack elements of T if T is a template argument pack,
3648 NULL otherwise. */
3650 tree
3652 {
3658 }
3660 /* In an ARGUMENT_PACK_SELECT, the actual underlying argument that the
3661 ARGUMENT_PACK_SELECT represents. */
3663 static tree
3665 {
3669 /* If the selected argument is an expansion E, that most likely means we were
3670 called from gen_elem_of_pack_expansion_instantiation during the
3671 substituting of an argument pack (of which the Ith element is a pack
3672 expansion, where I is ARGUMENT_PACK_SELECT_INDEX) into a pack expansion.
3673 In this case, the Ith element resulting from this substituting is going to
3674 be a pack expansion, which pattern is the pattern of E. Let's return the
3675 pattern of E, and gen_elem_of_pack_expansion_instantiation will build the
3676 resulting pack expansion from it. */
3678 {
3679 /* Make sure we aren't throwing away arg info. */
3682 }
3685 }
3687 /* Return a modification of ARGS that's suitable for preserving inside a hash
3688 table. In particular, this replaces each ARGUMENT_PACK_SELECT with its
3689 underlying argument. ARGS is copied (upon modification) iff COW_P. */
3691 static tree
3693 {
3698 {
3700 tree r;
3707 else
3710 {
3712 {
3715 }
3717 }
3718 }
3721 }
3723 /* True iff FN is a function representing a built-in variadic parameter
3724 pack. */
3726 bool
3728 {
3738 }
3740 /* True iff CALL is a call to a function representing a built-in variadic
3741 parameter pack. */
3743 static bool
3745 {
3749 }
3751 /* Return a TREE_VEC for the expansion of __integer_pack(HI). */
3753 static tree
3755 tree in_decl)
3756 {
3761 {
3763 {
3764 /* Work around maybe_convert_nontype_argument not doing this for
3765 dependent arguments. Don't use IMPLICIT_CONV_EXPR_NONTYPE_ARG
3766 because that will make tsubst_expr ignore it. */
3773 }
3778 }
3779 else
3780 {
3785 /* Calculate the largest value of len that won't make the size of the vec
3786 overflow an int. The compiler will exceed resource limits long before
3787 this, but it seems a decent place to diagnose. */
3791 {
3795 max);
3797 }
3805 }
3806 }
3808 /* Return a TREE_VEC for the expansion of built-in template parameter pack
3809 CALL. */
3811 static tree
3813 tree in_decl)
3814 {
3824 }
3826 /* Return true if the tree T has the extra args mechanism for
3827 avoiding partial instantiation. */
3829 static bool
3831 {
3836 }
3838 /* Structure used to track the progress of find_parameter_packs_r. */
3839 struct find_parameter_pack_data
3840 {
3841 /* TREE_LIST that will contain all of the parameter packs found by
3842 the traversal. */
3845 /* Set of AST nodes that have been visited by the traversal. */
3848 /* True iff we're making a type pack expansion. */
3851 /* True iff we found a subtree that has the extra args mechanism. */
3853 };
3855 /* Identifies all of the argument packs that occur in a template
3856 argument and appends them to the TREE_LIST inside DATA, which is a
3857 find_parameter_pack_data structure. This is a subroutine of
3858 make_pack_expansion and uses_parameter_packs. */
3859 static tree
3861 {
3867 #define WALK_SUBTREE(NODE) \
3868 cp_walk_tree (&(NODE), &find_parameter_packs_r, \
3869 ppd, ppd->visited) \
3871 /* Don't look through typedefs; we are interested in whether a
3872 parameter pack is actually written in the expression/type we're
3873 looking at, not the target type. */
3875 {
3876 /* But do look at arguments for an alias template. */
3883 }
3885 /* Identify whether this is a parameter pack or not. */
3887 {
3895 /* FALLTHRU */
3897 /* If the placeholder appears in the decl-specifier-seq of a function
3898 parameter pack (14.6.3), or the type-specifier-seq of a type-id that
3899 is a pack expansion, the invented template parameter is a template
3900 parameter pack. */
3910 {
3911 /* We don't want to walk into the type of a PARM_DECL,
3912 because we don't want to see the type parameter pack. */
3915 }
3920 {
3921 /* We don't want to walk into the type of a variadic capture proxy,
3922 because we don't want to see the type parameter pack. */
3925 }
3927 {
3929 find_parameter_packs_r,
3932 }
3944 /* Not a parameter pack. */
3946 }
3949 {
3950 /* Add this parameter pack to the list. */
3952 }
3961 /* This switch statement will return immediately if we don't find a
3962 parameter pack. ??? Should some of these be in cp_walk_subtrees? */
3964 {
3966 /* Check the template itself. */
3972 {
3974 /* Ignore the declaration of a capture proxy for a parameter pack. */
3978 /* Since we stop at typedefs above, we need to look through them at
3979 the point of the DECL_EXPR. */
3983 }
4010 {
4011 /* Since we defer implicit capture, look in the parms and body. */
4018 }
4021 {
4022 /* When traversing a DECLTYPE_TYPE_EXPR, we need to set
4023 type_pack_expansion_p to false so that any placeholders
4024 within the expression don't get marked as parameter packs. */
4032 }
4041 /* Don't walk into IF_STMT_EXTRA_ARGS. */
4048 {
4049 /* Local class, need to look through the whole definition.
4050 TYPE_BINFO might be unset for a partial instantiation. */
4055 }
4056 else
4057 /* Enum, look at the values. */
4071 }
4073 #undef WALK_SUBTREE
4076 }
4078 /* Determines if the expression or type T uses any parameter packs. */
4079 tree
4081 {
4090 }
4092 /* Turn ARG, which may be an expression, type, or a TREE_LIST
4093 representation a base-class initializer into a parameter pack
4094 expansion. If all goes well, the resulting node will be an
4095 EXPR_PACK_EXPANSION, TYPE_PACK_EXPANSION, or TREE_LIST,
4096 respectively. */
4097 tree
4099 {
4100 tree result;
4109 {
4110 /* A TREE_LIST with a non-null TREE_PURPOSE is for a base
4111 class initializer. In this case, the TREE_PURPOSE will be a
4112 _TYPE node (representing the base class expansion we're
4113 initializing) and the TREE_VALUE will be a TREE_LIST
4114 containing the initialization arguments.
4116 The resulting expansion looks somewhat different from most
4117 expansions. Rather than returning just one _EXPANSION, we
4118 return a TREE_LIST whose TREE_PURPOSE is a
4119 TYPE_PACK_EXPANSION containing the bases that will be
4120 initialized. The TREE_VALUE will be identical to the
4121 original TREE_VALUE, which is a list of arguments that will
4122 be passed to each base. We do not introduce any new pack
4123 expansion nodes into the TREE_VALUE (although it is possible
4124 that some already exist), because the TREE_PURPOSE and
4125 TREE_VALUE all need to be expanded together with the same
4126 _EXPANSION node. Note that the TYPE_PACK_EXPANSION in the
4127 resulting TREE_PURPOSE will mention the parameter packs in
4128 both the bases and the arguments to the bases. */
4129 tree purpose;
4130 tree value;
4133 /* Determine which parameter packs will be used by the base
4134 class expansion. */
4143 {
4146 arg);
4149 }
4152 {
4153 /* Collect the sets of parameter packs used in each of the
4154 initialization arguments. */
4156 {
4157 /* Determine which parameter packs will be expanded in this
4158 argument. */
4161 }
4162 }
4166 /* Create the pack expansion type for the base type. */
4172 /* Just use structural equality for these TYPE_PACK_EXPANSIONS;
4173 they will rarely be compared to anything. */
4177 }
4182 /* Build the PACK_EXPANSION_* node. */
4183 result = for_types
4188 {
4189 /* Propagate type and const-expression information. */
4192 /* Mark this read now, since the expansion might be length 0. */
4194 }
4195 else
4196 /* Just use structural equality for these TYPE_PACK_EXPANSIONS;
4197 they will rarely be compared to anything. */
4200 /* Determine which parameter packs will be expanded. */
4207 /* Make sure we found some parameter packs. */
4209 {
4211 {
4214 else
4216 }
4218 }
4223 /* If the pattern of this pack expansion contains a subtree that has
4224 the extra args mechanism for avoiding partial instantiation, then
4225 force this pack expansion to also use extra args. Otherwise
4226 partial instantiation of this pack expansion may not lower the
4227 level of some parameter packs within the pattern, which would
4228 confuse tsubst_pack_expansion later (PR101764). */
4232 }
4234 /* Checks T for any "bare" parameter packs, which have not yet been
4235 expanded, and issues an error if any are found. This operation can
4236 only be done on full expressions or types (e.g., an expression
4237 statement, "if" condition, etc.), because we could have expressions like:
4239 foo(f(g(h(args)))...)
4241 where "args" is a parameter pack. check_for_bare_parameter_packs
4242 should not be called for the subexpressions args, h(args),
4243 g(h(args)), or f(g(h(args))), because we would produce erroneous
4244 error messages.
4246 Returns TRUE and emits an error if there were bare parameter packs,
4247 returns FALSE otherwise. */
4248 bool
4250 {
4272 /* It's OK for a lambda to have an unexpanded parameter pack from the
4273 containing context, but do complain about unexpanded capture packs. */
4279 {
4280 /* We're in a lambda, but it isn't the innermost class.
4281 This should work, but currently doesn't. */
4284 }
4289 {
4295 }
4298 {
4301 {
4312 else
4317 else
4321 }
4324 }
4327 }
4329 /* Expand any parameter packs that occur in the template arguments in
4330 ARGS. */
4331 tree
4333 {
4342 /* First, determine if we need to expand anything, and the number of
4343 slots we'll need. */
4345 {
4350 {
4354 else
4356 }
4357 else
4358 {
4360 num_result_args++;
4361 }
4362 }
4364 /* If no expansion is necessary, we're done. */
4368 /* Expand arguments. */
4371 non_default_args_count =
4374 {
4377 {
4384 }
4385 else
4386 {
4389 }
4390 }
4394 }
4396 /* Checks if DECL shadows a template parameter.
4398 [temp.local]: A template-parameter shall not be redeclared within its
4399 scope (including nested scopes).
4401 Emits an error and returns TRUE if the DECL shadows a parameter,
4402 returns FALSE otherwise. */
4404 bool
4406 {
4407 tree olddecl;
4409 /* If we're not in a template, we can't possibly shadow a template
4410 parameter. */
4414 /* Figure out what we're shadowing. */
4418 /* If there's no previous binding for this name, we're not shadowing
4419 anything, let alone a template parameter. */
4423 /* If we're not shadowing a template parameter, we're done. Note
4424 that OLDDECL might be an OVERLOAD (or perhaps even an
4425 ERROR_MARK), so we can't just blithely assume it to be a _DECL
4426 node. */
4430 /* We check for decl != olddecl to avoid bogus errors for using a
4431 name inside a class. We check TPFI to avoid duplicate errors for
4432 inline member templates. */
4438 /* Don't complain about the injected class name, as we've already
4439 complained about the class itself. */
4446 else
4451 }
4453 /* Return a new TEMPLATE_PARM_INDEX with the indicated INDEX, LEVEL,
4454 ORIG_LEVEL, DECL, and TYPE. */
4456 static tree
4460 tree decl,
4461 tree type)
4462 {
4473 }
4476 {
4478 {
4488 }
4491 {
4496 }
4497 };
4501 /* Find the canonical type parameter for the given template type
4502 parameter. Returns the canonical type parameter, which may be TYPE
4503 if no such parameter existed. */
4505 tree
4507 {
4515 }
4517 /* Return a TEMPLATE_PARM_INDEX, similar to INDEX, but whose
4518 TEMPLATE_PARM_LEVEL has been decreased by LEVELS. If such a
4519 TEMPLATE_PARM_INDEX already exists, it is returned; otherwise, a
4520 new one is created. */
4522 static tree
4524 tsubst_flags_t complain)
4525 {
4530 {
4535 type);
4550 /* Template template parameters need this. */
4553 {
4565 }
4567 /* Attach the TPI to the decl. */
4570 else
4572 }
4575 }
4577 /* Process information from new template parameter PARM and append it
4578 to the LIST being built. This new parameter is a non-type
4579 parameter iff IS_NON_TYPE is true. This new parameter is a
4580 parameter pack iff IS_PARAMETER_PACK is true. The location of PARM
4581 is in PARM_LOC. */
4583 tree
4586 {
4592 {
4602 }
4609 {
4615 {
4616 /* [temp.param]
4618 The top-level cv-qualifiers on the template-parameter are
4619 ignored when determining its type. */
4624 && !is_parameter_pack
4625 /* If we're in a nested template parameter list, the template
4626 template parameter could be a parameter pack. */
4628 {
4629 /* This template parameter is not a parameter pack, but it
4630 should be. Complain about "bare" parameter packs. */
4633 /* Recover by calling this a parameter pack. */
4635 }
4636 }
4638 /* A template parameter is not modifiable. */
4647 current_template_depth,
4652 }
4653 else
4654 {
4655 tree t;
4659 {
4661 /* This is for distinguishing between real templates and template
4662 template parameters */
4665 /* any_template_parm_r expects to be able to get the targs of a
4666 DECL_TEMPLATE_RESULT. */
4675 }
4676 else
4677 {
4679 /* parm is either IDENTIFIER_NODE or NULL_TREE. */
4682 }
4689 current_template_depth,
4693 }
4701 /* Build requirements for the type/template parameter.
4702 This must be done after SET_DECL_TEMPLATE_PARM_P or
4703 process_template_parm could fail. */
4710 /* Build the parameter node linking the parameter declaration,
4711 its default argument (if any), and its constraints (if any). */
4717 else
4721 }
4723 /* The end of a template parameter list has been reached. Process the
4724 tree list into a parameter vector, converting each parameter into a more
4725 useful form. Type parameters are saved as IDENTIFIER_NODEs, and others
4726 as PARM_DECLs. */
4728 tree
4730 {
4733 /* Pop the dummy parameter level and add the real one. We do not
4734 morph the dummy parameter in place, as it might have been
4735 captured by a (nested) template-template-parm. */
4738 current_template_parms
4743 {
4749 }
4754 }
4756 // Explicitly indicate the end of the template parameter list. We assume
4757 // that the current template parameters have been constructed and/or
4758 // managed explicitly, as when creating new template template parameters
4759 // from a shorthand constraint.
4760 void
4762 {
4764 }
4766 /* end_template_decl is called after a template declaration is seen. */
4768 void
4770 {
4776 /* This matches the pushlevel in begin_template_parm_list. */
4781 }
4783 /* Takes a TEMPLATE_PARM_P or DECL_TEMPLATE_PARM_P node or a TREE_LIST
4784 thereof, and converts it into an argument suitable to be passed to
4785 the type substitution functions. Note that if the TREE_LIST contains
4786 an error_mark node, the returned argument is error_mark_node. */
4788 tree
4790 {
4801 {
4805 else
4807 }
4813 {
4815 {
4816 /* Turn this argument into a TYPE_ARGUMENT_PACK
4817 with a single element, which expands T. */
4826 }
4827 }
4828 else
4829 {
4831 {
4832 /* Turn this argument into a NONTYPE_ARGUMENT_PACK
4833 with a single element, which expands T. */
4843 }
4844 else
4846 }
4848 }
4850 /* If T looks like a generic template argument produced by template_parm_to_arg,
4851 return the corresponding template parameter, otherwise return NULL_TREE. */
4853 static tree
4855 {
4860 {
4865 }
4872 else
4874 }
4876 /* Given a single level of template parameters (a TREE_VEC), return it
4877 as a set of template arguments. */
4879 tree
4881 {
4891 }
4893 /* Given a set of template parameters, return them as a set of template
4894 arguments. The template parameters are represented as a TREE_VEC, in
4895 the form documented in cp-tree.h for template arguments. */
4897 tree
4899 {
4900 tree header;
4905 /* If there is only one level of template parameters, we do not
4906 create a TREE_VEC of TREE_VECs. Instead, we return a single
4907 TREE_VEC containing the arguments. */
4912 {
4917 else
4919 }
4922 }
4924 /* Within the declaration of a template, return the currently active
4925 template parameters as an argument TREE_VEC. */
4927 static tree
4929 {
4931 }
4933 /* Return the fully generic arguments for of TMPL, i.e. what
4934 current_template_args would be while parsing it. */
4936 tree
4938 {
4943 /* DECL_TEMPLATE_RESULT doesn't have the arguments we want. For a template
4944 template parameter, it has no TEMPLATE_INFO; for a partial
4945 specialization, it has the arguments for the primary template, and we
4951 }
4953 /* Return the template arguments corresponding to the template parameters of
4954 DECL's enclosing scope. When DECL is a member of a partial specialization,
4955 this returns the arguments for the partial specialization as opposed to those
4956 for the primary template, which is the main difference between this function
4957 and simply using e.g. the TYPE_TI_ARGS of DECL's DECL_CONTEXT. */
4959 tree
4961 {
4973 }
4975 /* Update the declared TYPE by doing any lookups which were thought to be
4976 dependent, but are not now that we know the SCOPE of the declarator. */
4978 tree
4980 {
4991 /* Don't bother building up the args in this case. */
4993 {
4994 /* tsubst in the args corresponding to the template parameters,
4995 including auto if present. Most things will be unchanged, but
4996 make_typename_type and tsubst_qualified_id will resolve
4997 TYPENAME_TYPEs and SCOPE_REFs that were previously dependent. */
5000 tree pushed;
5002 {
5006 }
5011 }
5017 {
5020 else
5022 }
5024 }
5026 /* Return a TEMPLATE_DECL corresponding to DECL, using the indicated
5027 template PARMS and constraints, CONSTR. If MEMBER_TEMPLATE_P is true,
5028 the new template is a member template. */
5030 static tree
5032 {
5044 /* Propagate module information from the decl. */
5048 }
5050 struct template_parm_data
5051 {
5052 /* The level of the template parameters we are currently
5053 processing. */
5056 /* The index of the specialization argument we are currently
5057 processing. */
5060 /* An array whose size is the number of template parameters. The
5061 elements are nonzero if the parameter has been used in any one
5062 of the arguments processed so far. */
5065 /* An array whose size is the number of template arguments. The
5066 elements are nonzero if the argument makes use of template
5067 parameters of this level. */
5069 };
5071 /* Subroutine of push_template_decl used to see if each template
5072 parameter in a partial specialization is used in the explicit
5073 argument list. If T is of the LEVEL given in DATA (which is
5074 treated as a template_parm_data*), then DATA->PARMS is marked
5075 appropriately. */
5077 static int
5079 {
5087 {
5090 }
5092 /* In C++17 the type of a non-type argument is a deduced context. */
5097 data,
5098 NULL,
5101 /* Return zero so that for_each_template_parm will continue the
5102 traversal of the tree; we want to mark *every* template parm. */
5104 }
5106 /* Process the partial specialization DECL. */
5108 static tree
5110 {
5117 tree inner_parms;
5118 tree inst;
5128 /* A concept cannot be specialized. */
5130 {
5133 }
5138 /* We check that each of the template parameters given in the
5139 partial specialization is used in the argument list to the
5140 specialization. For example:
5142 template <class T> struct S;
5143 template <class T> struct S<T*>;
5145 The second declaration is OK because `T*' uses the template
5146 parameter T, whereas
5148 template <class T> struct S<int>;
5150 is no good. Even trickier is:
5152 template <class T>
5153 struct S1
5154 {
5155 template <class U>
5156 struct S2;
5157 template <class U>
5158 struct S2<T>;
5159 };
5161 The S2<T> declaration is actually invalid; it is a
5162 full-specialization. Of course,
5164 template <class U>
5165 struct S2<T (*)(U)>;
5167 or some such would have been OK. */
5175 {
5180 NULL,
5182 }
5185 {
5186 /* One of the template parms was not used in a deduced context in the
5187 specialization. */
5189 {
5193 }
5197 }
5202 /* [temp.class.spec]
5204 The argument list of the specialization shall not be identical to
5205 the implicit argument list of the primary template. */
5206 tree main_args
5209 && (!flag_concepts
5211 {
5214 "any template arguments; to define the primary template, "
5216 else
5218 "template arguments and is not more constrained than "
5219 "the primary template; to define the primary template, "
5222 }
5224 /* A partial specialization that replaces multiple parameters of the
5225 primary template with a pack expansion is less specialized for those
5226 parameters. */
5228 {
5230 "primary template because it replaces multiple parameters "
5233 /* Avoid crash in process_partial_specialization. */
5235 }
5238 {
5241 /* Avoid crash below. */
5243 }
5245 /* If we aren't in a dependent class, we can actually try deduction. */
5247 /* FIXME we should be able to handle a partial specialization of a
5248 partial instantiation, but currently we can't (c++/41727). */
5251 {
5252 auto_diagnostic_group d;
5255 decl))
5257 maintmpl);
5258 }
5260 /* [temp.spec.partial]
5262 The type of a template parameter corresponding to a specialized
5263 non-type argument shall not be dependent on a parameter of the
5264 specialization.
5266 Also, we verify that pack expansions only occur at the
5267 end of the argument list. */
5270 {
5277 {
5278 /* Extract the arguments from the argument pack. We'll be
5279 iterating over these in the following loop. */
5282 }
5285 {
5287 /* Get the Jth argument in the parameter pack. */
5291 {
5292 /* Pack expansions must come at the end of the
5293 argument list. */
5296 {
5300 else
5303 }
5304 }
5307 /* We only care about the pattern. */
5313 /* This next two lines are the `argument expression is not just a
5314 simple identifier' condition and also the `specialized
5315 non-type argument' bit. */
5320 {
5321 /* Look at the corresponding template parameter,
5322 marking which template parameters its type depends
5323 upon. */
5327 {
5328 /* We haven't yet initialized TPD2. Do so now. */
5330 /* The number of parameters here is the number in the
5331 main template, which, as checked in the assertion
5332 above, is NARGS. */
5336 }
5338 /* Mark the template parameters. But this time, we're
5339 looking for the template parameters of the main
5340 template, not in the specialization. */
5347 NULL,
5351 {
5352 /* The type depended on some template parameters.
5353 If they are fully specialized in the
5354 specialization, that's OK. */
5363 "type %qT of template argument %qE depends "
5365 "type %qT of template argument %qE depends "
5367 type,
5368 arg);
5369 }
5370 }
5371 }
5372 }
5374 /* We should only get here once. */
5378 // Build the template decl.
5385 /* Give template template parms a DECL_CONTEXT of the template
5386 for which they are a parameter. */
5388 {
5392 }
5395 /* We didn't register this in check_explicit_specialization so we could
5396 wait until the constraints were set. */
5398 else
5405 /* Link the DECL_TEMPLATE_RESULT back to the partial TEMPLATE_DECL. */
5411 {
5417 {
5426 "declaration of %qD ambiguates earlier template "
5430 "partial specialization of %qD after instantiation "
5432 }
5433 }
5436 }
5438 /* PARM is a template parameter of some form; return the corresponding
5439 TEMPLATE_PARM_INDEX. */
5441 static tree
5443 {
5456 }
5458 /* Subroutine of fixed_parameter_pack_p below. Look for any template
5459 parameter packs used by the template parameter PARM. */
5461 static void
5463 {
5464 /* A type parm can't refer to another parm. */
5468 {
5472 }
5478 {
5482 else
5484 }
5485 }
5487 /* PARM is a template parameter pack. Return any parameter packs used in
5488 its type or the type of any of its template parameters. If there are
5489 any such packs, it will be instantiated into a fixed template parameter
5490 list by partial instantiation rather than be fully deduced. */
5492 tree
5494 {
5495 /* This can only be true in a member template. */
5498 /* This can only be true for a parameter pack. */
5501 /* A type parm can't refer to another parm. */
5515 }
5517 /* Check that a template declaration's use of default arguments and
5518 parameter packs is not invalid. Here, PARMS are the template
5519 parameters. IS_PRIMARY is true if DECL is the thing declared by
5520 a primary template. IS_PARTIAL is true if DECL is a partial
5521 specialization.
5523 IS_FRIEND_DECL is nonzero if DECL is either a non-defining friend
5524 function template declaration or a friend class template
5525 declaration. In the function case, 1 indicates a declaration, 2
5526 indicates a redeclaration. When IS_FRIEND_DECL=2, no errors are
5527 emitted for extraneous default arguments.
5529 Returns TRUE if there were no errors found, FALSE otherwise. */
5531 bool
5534 {
5537 tree parm_level;
5540 /* [temp.param]
5542 A default template-argument shall not be specified in a
5543 function template declaration or a function template definition, nor
5544 in the template-parameter-list of the definition of a member of a
5545 class template. */
5549 /* You can't have a function template declaration in a local
5550 scope, nor you can you define a member of a class template in a
5551 local scope. */
5559 /* A lambda doesn't have an explicit declaration; don't complain
5560 about the parms of the enclosing class. */
5567 /* If this is either a friend defined in the scope of the class
5568 or a member function. */
5574 /* And, if it was a member function, it really was defined in
5575 the scope of the class. */
5578 /* We already checked these parameters when the template was
5579 declared, so there's no need to do it again now. This function
5580 was defined in class scope, but we're processing its body now
5581 that the class is complete. */
5584 /* Core issue 226 (C++0x only): the following only applies to class
5585 templates. */
5588 {
5589 /* [temp.param]
5591 If a template-parameter has a default template-argument, all
5592 subsequent template-parameters shall have a default
5593 template-argument supplied. */
5595 {
5602 {
5612 {
5614 /* For better subsequent error-recovery, we indicate that
5615 there should have been a default argument. */
5618 }
5620 && !is_friend_decl
5621 /* Don't complain about an enclosing partial
5622 specialization. */
5627 /* A fixed parameter pack will be partially
5628 instantiated into a fixed length list. */
5630 {
5631 /* A primary class template, primary variable template
5632 (DR 2032), or alias template can only have one
5633 parameter pack, at the end of the template
5634 parameter list. */
5642 }
5643 }
5644 }
5645 }
5648 || is_partial
5649 || !is_primary
5651 /* For an ordinary class template, default template arguments are
5652 allowed at the innermost level, e.g.:
5653 template <class T = int>
5654 struct S {};
5655 but, in a partial specialization, they're not allowed even
5656 there, as we have in [temp.class.spec]:
5658 The template parameter list of a specialization shall not
5659 contain default template argument values.
5661 So, for a partial specialization, or for a function template
5662 (in C++98/C++03), we look at all of them. */
5663 ;
5664 else
5665 /* But, for a primary class template that is not a partial
5666 specialization we look at all template parameters except the
5667 innermost ones. */
5670 /* Figure out what error message to issue. */
5685 else
5686 /* Per [temp.param]/9, "A default template-argument shall not be
5687 specified in the template-parameter-lists of the definition of
5688 a member of a class template that appears outside of the member's
5689 class.", thus if we aren't handling a member of a class template
5690 there is no need to examine the parameters. */
5694 /* If we're inside a class definition, there's no need to
5695 examine the parameters to the class itself. On the one
5696 hand, they will be checked when the class is defined, and,
5697 on the other, default arguments are valid in things like:
5698 template <class T = double>
5699 struct S { template <class U> void f(U); };
5700 Here the default argument for `S' has no bearing on the
5701 declaration of `f'. */
5703 else
5704 /* Check everything. */
5710 {
5717 {
5722 {
5724 {
5731 }
5733 /* Clear out the default argument so that we are not
5734 confused later. */
5736 }
5737 }
5739 /* At this point, if we're still interested in issuing messages,
5740 they must apply to classes surrounding the object declared. */
5744 }
5747 }
5749 /* Worker for push_template_decl_real, called via
5750 for_each_template_parm. DATA is really an int, indicating the
5751 level of the parameters we are interested in. If T is a template
5752 parameter of that level, return nonzero. */
5754 static int
5756 {
5762 else
5765 }
5767 /* Worker for uses_outer_template_parms, called via for_each_template_parm.
5768 DATA is really an int, indicating the innermost outer level of parameters.
5769 If T is a template parameter of that level or further out, return
5770 nonzero. */
5772 static int
5774 {
5780 else
5783 }
5785 /* Creates a TEMPLATE_DECL for the indicated DECL using the template
5786 parameters given by current_template_args, or reuses a
5787 previously existing one, if appropriate. Returns the DECL, or an
5788 equivalent one, if it is replaced via a call to duplicate_decls.
5790 If IS_FRIEND is true, DECL is a friend declaration. */
5792 tree
5794 {
5798 /* See if this is a partial specialization. */
5807 /* No surprising friend functions. */
5812 tree ctx;
5814 /* For a friend, we want the context of the friend, not
5815 the type of which it is a friend. */
5819 /* In the case of a virtual function, we want the class in which
5820 it is defined. */
5822 else
5823 /* Otherwise, if we're currently defining some class, the DECL
5824 is assumed to be a member of the class. */
5833 /* See if this is a primary template. */
5837 /* A friend template that specifies a class context, i.e.
5838 template <typename T> friend void A<T>::f();
5839 is not primary. */
5840 ;
5842 /* Lambdas are not primary. */
5843 ;
5844 else
5847 /* True if the template is a member template, in the sense of
5848 [temp.mem]. */
5852 {
5860 {
5863 }
5865 {
5867 {
5870 }
5872 {
5873 /* [temp.mem]
5875 A destructor shall not be a member template. */
5879 }
5886 {
5887 /* [basic.stc.dynamic.allocation]
5889 An allocation function can be a function
5890 template. ... Template allocation functions shall
5891 have two or more parameters. */
5894 }
5895 }
5901 /* alias-declaration */
5907 else
5908 {
5911 }
5912 }
5919 /* Check to see that the rules regarding the use of default
5920 arguments are not being violated. We check args for a friend
5921 functions when we know whether it's a definition, introducing
5922 declaration or re-declaration. */
5927 /* Ensure that there are no parameter packs in the type of this
5928 declaration that have not been expanded. */
5930 {
5931 /* Check each of the arguments individually to see if there are
5932 any bare parameter packs. */
5938 {
5941 {
5942 /* This is a PARM_DECL that contains unexpanded parameter
5943 packs. We have already complained about this in the
5944 check_for_bare_parameter_packs call, so just replace
5945 these types with ERROR_MARK_NODE. */
5948 }
5952 }
5954 /* Check for bare parameter packs in the return type and the
5955 exception specifiers. */
5957 /* Errors were already issued, set return type to int
5958 as the frontend doesn't expect error_mark_node as
5959 the return type. */
5963 }
5964 else
5965 {
5969 {
5972 }
5977 }
5986 {
5987 /* Does not get a template head. */
5990 }
5997 {
6002 /* If DECL is a TYPE_DECL for a class-template, then there won't
6003 be DECL_LANG_SPECIFIC. The information equivalent to
6004 DECL_TEMPLATE_INFO is found in TYPE_TEMPLATE_INFO instead. */
6008 {
6009 /* Since a template declaration already existed for this
6010 class-type, we must be redeclaring it here. Make sure
6011 that the redeclaration is valid. */
6013 current_template_parms,
6015 /* We don't need to create a new TEMPLATE_DECL; just use the
6016 one we already had. */
6018 }
6019 else
6020 {
6022 member_template_p);
6027 {
6028 /* A specialization of a member template of a template
6029 class. */
6033 }
6034 }
6035 }
6036 else
6037 {
6043 {
6046 }
6054 {
6055 /* The declaration is a specialization of a member
6056 template, declared outside the class. Therefore, the
6057 innermost template arguments will be NULL, so we
6058 replace them with the arguments determined by the
6059 earlier call to check_explicit_specialization. */
6062 tree new_tmpl
6064 member_template_p);
6072 args,
6075 }
6077 /* Make sure the template headers we got make sense. */
6082 {
6087 }
6088 else
6090 {
6095 {
6099 else
6103 /* Avoid crash in import_export_decl. */
6106 }
6111 /* Can happen in erroneous input. */
6113 else
6115 }
6117 /* Check that the parms are used in the appropriate qualifying scopes
6118 in the declarator. */
6122 {
6128 /* Avoid crash in import_export_decl. */
6131 }
6133 /* Check that the constraints for each enclosing template scope are
6134 consistent with the original declarations. */
6136 {
6140 {
6143 }
6145 {
6147 {
6151 }
6154 }
6155 }
6156 }
6161 {
6162 /* Push template declarations for global functions and types.
6163 Note that we do not try to push a global template friend
6164 declared in a template class; such a thing may well depend on
6165 the template parameters of the class and we'll push it when
6166 instantiating the befriending class. */
6169 {
6174 /* pushdecl may have found an existing template. */
6176 {
6179 }
6180 }
6182 {
6183 /* Record this decl as belonging to the current class. It's
6184 not chained onto anything else. */
6188 }
6189 }
6191 /* The type may have been completed, or (erroneously) changed. */
6195 {
6197 {
6202 /* Give template template parms a DECL_CONTEXT of the template
6203 for which they are a parameter. */
6206 {
6210 }
6214 {
6217 {
6218 /* ??? Why don't we do this here for all templates? */
6221 }
6222 }
6223 }
6225 /* The DECL_TI_ARGS of DECL contains full set of arguments
6226 referring wback to its most general template. If TMPL is a
6227 specialization, ARGS may only have the innermost set of
6228 arguments. Add the missing argument levels if necessary. */
6236 else
6237 {
6240 }
6241 }
6244 && !is_friend
6247 /* Set DECL_COMDAT on template instantiations; if we force
6248 them to be emitted by explicit instantiation,
6249 mark_needed will tell cgraph to do the right thing. */
6255 }
6257 /* FN is an inheriting constructor that inherits from the constructor
6258 template INHERITED; turn FN into a constructor template with a matching
6259 template header. */
6261 tree
6263 {
6264 tree inner_parms
6267 tree parms
6276 }
6278 /* Called when a class template TYPE is redeclared with the indicated
6279 template PARMS, e.g.:
6281 template <class T> struct S;
6282 template <class T> struct S {}; */
6284 bool
6286 {
6287 tree tmpl;
6288 tree tmpl_parms;
6292 {
6295 }
6299 /* The type is nested in some template class. Nothing to worry
6300 about here; there are no new template parameters for the nested
6301 type. */
6305 {
6307 tmpl);
6309 }
6315 {
6325 }
6328 {
6329 tree tmpl_parm;
6330 tree parm;
6342 /* TMPL_PARM and PARM can be either TYPE_DECL, PARM_DECL, or
6343 TEMPLATE_DECL. */
6353 {
6354 auto_diagnostic_group d;
6358 else
6361 }
6363 /* The parameters can be declared to introduce different
6364 constraints. */
6368 {
6369 auto_diagnostic_group d;
6375 }
6377 /* Give each template template parm in this redeclaration a
6378 DECL_CONTEXT of the template for which they are a parameter. */
6380 {
6384 }
6385 }
6394 /* Two classes with different constraints declare different entities. */
6396 {
6397 auto_diagnostic_group d;
6403 }
6406 }
6408 /* The actual substitution part of instantiate_non_dependent_expr,
6409 to be used when the caller has already checked
6410 !instantiation_dependent_uneval_expression_p (expr)
6411 and cleared processing_template_decl. */
6413 tree
6415 {
6417 }
6419 /* Instantiate the non-dependent expression EXPR. */
6421 tree
6424 {
6429 {
6430 /* The caller should have checked this already. */
6432 processing_template_decl_sentinel s;
6434 }
6436 }
6438 /* Like instantiate_non_dependent_expr, but return NULL_TREE if the
6439 expression is dependent or non-constant. */
6441 tree
6443 {
6447 {
6450 else
6451 {
6452 processing_template_decl_sentinel s;
6454 }
6455 }
6457 }
6459 /* True iff T is a specialization of a variable template. */
6461 bool
6463 {
6468 }
6470 /* Return TRUE iff T is a type alias, a TEMPLATE_DECL for an alias
6471 template declaration, or a TYPE_DECL for an alias declaration. */
6473 bool
6475 {
6483 }
6485 /* If T is a specialization of an alias template, return it; otherwise return
6486 NULL_TREE. If TRANSPARENT_TYPEDEFS is true, look through other aliases. */
6488 tree
6491 {
6495 /* It's an alias template specialization if it's an alias and its
6496 TYPE_NAME is a specialization of a primary template. */
6498 {
6505 transparent_typedefs);
6506 }
6509 }
6511 /* A cache of the result of complex_alias_template_p. */
6515 /* Data structure for complex_alias_template_*. */
6517 struct uses_all_template_parms_data
6518 {
6521 };
6523 /* walk_tree callback for complex_alias_template_p. */
6525 static tree
6527 {
6532 {
6537 {
6541 }
6544 }
6549 /* An alias template with a pack expansion that expands a pack from the
6550 enclosing class needs to be considered complex, to avoid confusion with
6551 the same pack being used as an argument to the alias's own template
6552 parameter (91966). */
6555 {
6564 /* Consider the expanded packs to be used outside the expansion... */
6566 }
6568 /* ...but don't walk into the pattern. Consider PR104008:
6570 template <typename T, typename... Ts>
6571 using IsOneOf = disjunction<is_same<T, Ts>...>;
6573 where IsOneOf seemingly uses all of its template parameters in its
6574 expansion (and does not expand a pack from the enclosing class), so the
6575 alias was not marked as complex. However, if it is used like
6576 "IsOneOf<T>", the empty pack for Ts means that T no longer appears in the
6577 expansion. So only Ts is considered used by the pack expansion. */
6581 }
6583 /* An alias template is complex from a SFINAE perspective if a template-id
6584 using that alias can be ill-formed when the expansion is not, as with
6585 the void_t template.
6587 If this predicate returns true in the ordinary case, the out parameter
6588 SEEN_OUT is set to a TREE_VEC containing boolean_true_node at element I if
6589 the I'th template parameter of the alias template is used in the alias. */
6591 static bool
6593 {
6598 /* A renaming alias isn't complex. */
6602 /* Any other constrained alias is complex. */
6610 {
6620 }
6633 {
6636 }
6640 {
6645 }
6649 }
6651 /* If T is a specialization of a complex alias template with a dependent
6652 argument for an unused template parameter, return it; otherwise return
6653 NULL_TREE. If T is a typedef to such a specialization, return the
6654 specialization. */
6656 tree
6658 {
6667 {
6670 {
6673 {
6676 }
6677 else
6678 {
6684 }
6687 }
6688 }
6691 {
6694 }
6697 }
6699 /* Return the number of innermost template parameters in TMPL. */
6701 static int
6703 {
6706 }
6708 /* Return either TMPL or another template that it is equivalent to under DR
6709 1286: An alias that just changes the name of a template is equivalent to
6710 the other template. */
6712 static tree
6714 {
6717 {
6718 /* Determine if the alias is equivalent to an underlying template. */
6720 /* The underlying type may have been ill-formed. Don't proceed. */
6733 /* Does the alias add cv-quals? */
6741 /* Are any default template arguments equivalent? */
6746 {
6751 }
6753 /* If TMPL adds or changes any constraints, it isn't equivalent. I think
6754 it's appropriate to treat a less-constrained alias as equivalent. */
6758 /* Alias is equivalent. Strip it and repeat. */
6760 }
6761 top_break:;
6764 }
6766 /* Subroutine of convert_nontype_argument. Converts EXPR to TYPE, which
6767 must be a reference-to-function or a pointer-to-function type, as specified
6768 in [temp.arg.nontype]: disambiguate EXPR if it is an overload set,
6769 and check that the resulting function has external linkage. */
6771 static tree
6773 tsubst_flags_t complain)
6774 {
6777 linkage_kind linkage;
6795 /* [temp.arg.nontype]/1
6797 A template-argument for a non-type, non-template template-parameter
6798 shall be one of:
6799 [...]
6800 -- the address of an object or function with external [C++11: or
6801 internal] linkage. */
6805 {
6807 {
6814 else
6817 }
6819 }
6824 {
6826 {
6832 else
6836 }
6838 }
6840 accept:
6842 {
6845 else
6847 }
6852 }
6854 /* Subroutine of convert_nontype_argument.
6855 Check if EXPR of type TYPE is a valid pointer-to-member constant.
6856 Emit an error otherwise. */
6858 static bool
6860 tsubst_flags_t complain)
6861 {
6877 {
6883 else
6885 }
6887 }
6889 /* Returns TRUE iff the address of OP is value-dependent.
6891 14.6.2.4 [temp.dep.temp]:
6892 A non-integral non-type template-argument is dependent if its type is
6893 dependent or it has either of the following forms
6894 qualified-id
6895 & qualified-id
6896 and contains a nested-name-specifier which specifies a class-name that
6897 names a dependent type.
6899 We generalize this to just say that the address of a member of a
6900 dependent class is value-dependent; the above doesn't cover the
6901 address of a static data member named with an unqualified-id. */
6903 static bool
6905 {
6908 /* We could use get_inner_reference here, but there's no need;
6909 this is only relevant for template non-type arguments, which
6910 can only be expressed as &id-expression. */
6912 {
6923 }
6926 }
6928 /* The next set of functions are used for providing helpful explanatory
6929 diagnostics for failed overload resolution. Their messages should be
6930 indented by two spaces for consistency with the messages in
6931 call.cc */
6933 static int
6935 {
6937 }
6939 /* Other failure functions should call this one, to provide a single function
6940 for setting a breakpoint on. */
6942 static int
6944 {
6946 }
6948 static int
6950 {
6955 }
6957 static int
6959 {
6965 }
6967 static int
6969 {
6973 }
6975 static int
6977 {
6980 " template parameter %qD is not a parameter pack, but "
6984 }
6986 static int
6988 {
6991 " template argument %qE does not match "
6995 }
6997 static int
6999 {
7003 }
7005 static int
7007 {
7013 }
7015 static int
7017 {
7019 {
7024 else
7026 " deduced conflicting values for non-type parameter "
7028 }
7030 }
7032 static int
7034 {
7037 " variable-sized array type %qT is not "
7039 arg);
7041 }
7043 static int
7045 {
7049 arg);
7051 }
7053 static int
7055 {
7057 {
7063 else
7068 }
7070 }
7072 static int
7074 {
7076 }
7078 static int
7081 {
7083 }
7085 static int
7088 {
7094 }
7096 static int
7099 {
7102 {
7110 }
7112 }
7114 static int
7116 {
7119 " template parameters of a template template argument are "
7122 }
7124 static int
7126 {
7132 }
7134 static int
7136 {
7141 }
7143 /* Subroutine of convert_nontype_argument, to check whether EXPR, as an
7144 argument for TYPE, points to an unsuitable object.
7146 Also adjust the type of the index in C++20 array subobject references. */
7148 static bool
7150 {
7152 {
7153 CASE_CONVERT:
7155 complain);
7159 complain);
7162 {
7166 }
7170 {
7176 {
7180 /* Canonicalize array offsets to ptrdiff_t; how they were
7181 written doesn't matter for subobject identity. */
7184 }
7187 {
7190 "%qE is not a valid template argument of type %qT "
7194 }
7196 {
7199 "%qE is not a valid template argument of type %qT "
7203 }
7206 {
7209 "%qE is not a valid template argument of type %qT "
7212 }
7213 /* C++17: For a non-type template-parameter of reference or pointer
7214 type, the value of the constant expression shall not refer to (or
7215 for a pointer type, shall not be the address of):
7216 * a subobject (4.5),
7217 * a temporary object (15.2),
7218 * a string literal (5.13.5),
7219 * the result of a typeid expression (8.2.8), or
7220 * a predefined __func__ variable (11.4.1). */
7222 {
7225 decl);
7227 }
7229 && !(same_type_ignoring_top_level_qualifiers_p
7232 {
7237 }
7239 {
7243 decl);
7245 }
7246 }
7254 else
7255 {
7257 {
7260 "because %qD is a variable, not the address of "
7263 }
7264 else
7265 {
7271 }
7272 }
7273 }
7276 }
7278 /* Return a VAR_DECL for the C++20 template parameter object corresponding to
7279 template argument EXPR. */
7281 static tree
7283 {
7288 {
7293 }
7297 /* This is no longer a compound literal. */
7301 }
7303 /* The template arguments corresponding to template parameter objects of types
7304 that contain pointers to members. */
7308 /* Find or build an nttp object for (already-validated) EXPR with name
7309 NAME. */
7311 tree
7313 {
7330 {
7331 /* If EXPR contains any PTRMEM_CST, they will get clobbered by
7332 lower_var_init before we're done mangling. So store the original
7333 value elsewhere. */
7336 }
7341 }
7343 /* Return the actual template argument corresponding to template parameter
7344 object VAR. */
7346 tree
7348 {
7352 }
7354 /* Attempt to convert the non-type template parameter EXPR to the
7355 indicated TYPE. If the conversion is successful, return the
7356 converted value. If the conversion is unsuccessful, return
7357 NULL_TREE if we issued an error message, or error_mark_node if we
7358 did not. We issue error messages for out-and-out bad template
7359 parameters, but not simply because the conversion failed, since we
7360 might be just trying to do argument deduction. Both TYPE and EXPR
7361 must be non-dependent.
7363 The conversion follows the special rules described in
7364 [temp.arg.nontype], and it is much more strict than an implicit
7365 conversion.
7367 This function is called twice for each template argument (see
7368 lookup_template_class for a more accurate description of this
7369 problem). This means that we need to handle expressions which
7370 are not valid in a C++ source, but can be created from the
7371 first call (for instance, casts to perform conversions). These
7372 hacks can go away after we fix the double coercion problem. */
7374 static tree
7376 {
7377 tree expr_type;
7380 /* Detect immediately string literals as invalid non-type argument.
7381 This special-case is not needed for correctness (we would easily
7382 catch this later), but only to provide better diagnostic for this
7383 common user mistake. As suggested by DR 100, we do not mention
7384 linkage issues in the diagnostic as this is not the point. */
7386 {
7392 }
7394 /* Add the ADDR_EXPR now for the benefit of
7395 value_dependent_expression_p. */
7398 {
7402 }
7404 /* If we are in a template, EXPR may be non-dependent, but still
7405 have a syntactic, rather than semantic, form. For example, EXPR
7406 might be a SCOPE_REF, rather than the VAR_DECL to which the
7407 SCOPE_REF refers. Preserving the qualifying scope is necessary
7408 so that access checking can be performed when the template is
7409 instantiated -- but here we need the resolved form so that we can
7410 convert the argument. */
7422 /* If the argument is non-dependent, perform any conversions in
7423 non-dependent context as well. */
7431 else
7434 /* 14.3.2/5: The null pointer{,-to-member} conversion is applied
7435 to a non-type argument of "nullptr". */
7439 /* In C++11, integral or enumeration non-type template arguments can be
7440 arbitrary constant expressions. Pointer and pointer to
7441 member arguments can be general constant expressions that evaluate
7442 to a null value, but otherwise still need to be of a specific form. */
7444 {
7446 /* A PTRMEM_CST is already constant, and a valid template
7447 argument for a parameter of pointer to member type, we just want
7448 to leave it in that form rather than lower it to a
7452 {
7453 /* C++17: A template-argument for a non-type template-parameter shall
7454 be a converted constant expression (8.20) of the type of the
7455 template-parameter. */
7458 /* Make sure we return NULL_TREE only if we have really issued
7459 an error, as described above. */
7462 {
7465 }
7468 /* EXPR may have become value-dependent. */
7470 }
7472 {
7477 }
7478 }
7482 else
7485 /* HACK: Due to double coercion, we can get a
7486 NOP_EXPR<REFERENCE_TYPE>(ADDR_EXPR<POINTER_TYPE> (arg)) here,
7487 which is the tree that we built on the first call (see
7488 below when coercing to reference to object or to reference to
7489 function). We just strip everything and get to the arg.
7490 See g++.old-deja/g++.oliva/template4.C and g++.dg/template/nontype9.C
7491 for examples. */
7493 {
7494 /* Check this before we strip *& to avoid redundancy. */
7503 {
7504 /* ??? Maybe we could use convert_from_reference here, but we
7505 would need to relax its constraints because the NOP_EXPR
7506 could actually change the type to something more cv-qualified,
7507 and this is not folded by convert_from_reference. */
7512 && (same_type_ignoring_top_level_qualifiers_p
7515 {
7518 }
7519 }
7520 }
7522 /* [temp.arg.nontype]/5, bullet 1
7524 For a non-type template-parameter of integral or enumeration type,
7525 integral promotions (_conv.prom_) and integral conversions
7526 (_conv.integral_) are applied. */
7529 {
7531 {
7536 }
7541 /* Notice that there are constant expressions like '4 % 0' which
7542 do not fold into integer constants. */
7544 {
7546 {
7550 else
7556 /* else cxx_constant_value complained but gave us
7557 a real constant, so go ahead. */
7559 {
7560 /* Some assemble time constant expressions like
7561 (intptr_t)&&lab1 - (intptr_t)&&lab2 or
7562 4 + (intptr_t)&&var satisfy reduced_constant_expression_p
7563 as we can emit them into .rodata initializers of
7564 variables, yet they can't fold into an INTEGER_CST at
7565 compile time. Refuse them here. */
7570 }
7571 }
7572 else
7574 }
7576 /* Avoid typedef problems. */
7579 }
7580 /* [temp.arg.nontype]/5, bullet 2
7582 For a non-type template-parameter of type pointer to object,
7583 qualification conversions (_conv.qual_) and the array-to-pointer
7584 conversion (_conv.array_) are applied. */
7586 {
7589 /* Look through any NOP_EXPRs around an ADDR_EXPR, whether they come from
7590 decay_conversion or an explicit cast. If it's a problematic cast,
7591 we'll complain about it below. */
7593 {
7598 {
7601 }
7602 }
7604 /* [temp.arg.nontype]/1 (TC1 version, DR 49):
7606 A template-argument for a non-type, non-template template-parameter
7607 shall be one of: [...]
7609 -- the name of a non-type template-parameter;
7610 -- the address of an object or function with external linkage, [...]
7611 expressed as "& id-expression" where the & is optional if the name
7612 refers to a function or array, or if the corresponding
7613 template-parameter is a reference.
7615 Here, we do not care about functions, as they are invalid anyway
7616 for a parameter of type pointer-to-object. */
7619 /* Non-type template parameters are OK. */
7620 ;
7625 /* Other values, like integer constants, might be valid
7626 non-type arguments of some other type. */
7636 }
7637 /* [temp.arg.nontype]/5, bullet 3
7639 For a non-type template-parameter of type reference to object, no
7640 conversions apply. The type referred to by the reference may be more
7641 cv-qualified than the (otherwise identical) type of the
7642 template-argument. The template-parameter is bound directly to the
7643 template-argument, which must be an lvalue. */
7645 {
7647 expr_type))
7651 {
7656 }
7659 {
7664 }
7666 /* [temp.arg.nontype]/1
7668 A template-argument for a non-type, non-template template-parameter
7669 shall be one of: [...]
7671 -- the address of an object or function with external linkage. */
7674 {
7677 {
7680 "because a reference variable does not have a constant "
7683 }
7684 }
7687 /* OK, dependent reference. We don't want to ask whether a DECL is
7689 else
7690 {
7695 }
7699 }
7700 /* [temp.arg.nontype]/5, bullet 4
7702 For a non-type template-parameter of type pointer to function, only
7703 the function-to-pointer conversion (_conv.func_) is applied. If the
7704 template-argument represents a set of overloaded functions (or a
7705 pointer to such), the matching function is selected from the set
7706 (_over.over_). */
7708 {
7709 /* If the argument is a template-id, we might not have enough
7710 context information to decay the pointer. */
7712 {
7716 }
7719 /* Null pointer values are OK in C++11. */
7725 }
7726 /* [temp.arg.nontype]/5, bullet 5
7728 For a non-type template-parameter of type reference to function, no
7729 conversions apply. If the template-argument represents a set of
7730 overloaded functions, the matching function is selected from the set
7731 (_over.over_). */
7733 {
7735 {
7737 {
7742 }
7744 }
7749 }
7750 /* [temp.arg.nontype]/5, bullet 6
7752 For a non-type template-parameter of type pointer to member function,
7753 no conversions apply. If the template-argument represents a set of
7754 overloaded member functions, the matching member function is selected
7755 from the set (_over.over_). */
7757 {
7762 /* [temp.arg.nontype] bullet 1 says the pointer to member
7763 expression must be a pointer-to-member constant. */
7768 /* Repeated conversion can't deal with a conversion that turns PTRMEM_CST
7769 into a CONSTRUCTOR, so build up a new PTRMEM_CST instead. */
7772 }
7773 /* [temp.arg.nontype]/5, bullet 7
7775 For a non-type template-parameter of type pointer to data member,
7776 qualification conversions (_conv.qual_) are applied. */
7778 {
7779 /* [temp.arg.nontype] bullet 1 says the pointer to member
7780 expression must be a pointer-to-member constant. */
7788 }
7790 {
7792 {
7797 }
7799 }
7801 {
7802 /* Replace the argument with a reference to the corresponding template
7803 parameter object. */
7808 }
7809 /* A template non-type parameter must be one of the above. */
7810 else
7813 /* Sanity check: did we actually convert the argument to the
7814 right type? */
7818 }
7820 /* Subroutine of coerce_template_template_parms, which returns 1 if
7821 PARM_PARM and ARG_PARM match using the rule for the template
7822 parameters of template template parameters. Both PARM and ARG are
7823 template parameters; the rest of the arguments are the same as for
7824 coerce_template_template_parms.
7825 */
7826 static int
7828 tree arg,
7829 tsubst_flags_t complain,
7830 tree in_decl,
7831 tree outer_args)
7832 {
7841 {
7843 /* We encounter instantiations of templates like
7844 template <template <template <class> class> class TT>
7845 class C; */
7846 {
7850 }
7851 /* Fall through. */
7856 /* Argument is a parameter pack but parameter is not. */
7861 /* The tsubst call is used to handle cases such as
7863 template <int> class C {};
7864 template <class T, template <T> class TT> class D {};
7865 D<int, C> d;
7867 i.e. the parameter list of TT depends on earlier parameters. */
7869 {
7874 }
7878 /* Argument is a parameter pack but parameter is not. */
7885 }
7888 }
7890 /* Coerce template argument list ARGLIST for use with template
7891 template-parameter TEMPL. */
7893 static tree
7895 tsubst_flags_t complain)
7896 {
7897 /* Consider an example where a template template parameter declared as
7899 template <class T, class U = std::allocator<T> > class TT
7901 The template parameter level of T and U are one level larger than
7902 of TT. To proper process the default argument of U, say when an
7903 instantiation `TT<int>' is seen, we need to build the full
7904 arguments containing {int} as the innermost level. Outer levels,
7905 available when not appearing as default template argument, can be
7906 obtained from the arguments of the enclosing template.
7908 Suppose that TT is later substituted with std::vector. The above
7909 instantiation is `TT<int, std::allocator<T> >' with TT at
7910 level 1, and T at level 2, while the template arguments at level 1
7911 becomes {std::vector} and the inner level 2 is {int}. */
7917 {
7918 /* This is an argument of the current template, so we haven't set
7919 DECL_CONTEXT yet. We can also get here when level-lowering a
7920 bound ttp. */
7921 tree relevant_template_parms;
7923 /* Parameter levels that are greater than the level of the given
7924 template template parm are irrelevant. */
7931 }
7938 }
7940 /* A cache of template template parameters with match-all default
7941 arguments. */
7944 /* T is a bound template template-parameter. Copy its arguments into default
7945 arguments of the template template-parameter's template parameters. */
7947 static tree
7949 {
7972 {
7975 {
7978 }
7979 }
7983 tree gen_ntmpl;
7986 else
7996 }
7998 /* ARG is a bound potential template template-argument, and PARGS is a list
7999 of arguments for the corresponding template template-parameter. Adjust
8000 PARGS as appropriate for application to ARG's template, and if ARG is a
8001 BOUND_TEMPLATE_TEMPLATE_PARM, possibly adjust it to add default template
8002 arguments to the template template parameter. */
8004 static tree
8006 {
8010 {
8011 /* When comparing two template template-parameters in partial ordering,
8012 rewrite the one currently being used as an argument to have default
8013 arguments for all parameters. */
8019 }
8020 else
8021 {
8022 tree aparms
8025 }
8028 }
8030 /* Subroutine of unify for the case when PARM is a
8031 BOUND_TEMPLATE_TEMPLATE_PARM. */
8033 static int
8036 {
8040 /* The template template parm might be variadic and the argument
8041 not, so flatten both argument lists. */
8046 {
8047 /* In keeping with P0522R0, adjust P's template arguments
8048 to apply to A's template; then flatten it again. */
8056 /* If the P0522 adjustment eliminated a pack expansion, deduce
8057 empty packs. */
8063 }
8064 else
8065 {
8066 /* Deduce arguments T, i from TT<T> or TT<i>.
8067 We check each element of PARMVEC and ARGVEC individually
8068 rather than the whole TREE_VEC since they can have
8069 different number of elements, which is allowed under N2555. */
8073 /* Check if the parameters end in a pack, making them
8074 variadic. */
8081 /* If the template argument list of P contains a pack
8082 expansion that is not the last template argument, the
8083 entire template argument list is a non-deduced
8084 context. */
8102 DEDUCE_EXACT,
8105 }
8108 }
8110 /* Return 1 if PARM_TMPL and ARG_TMPL match using rule for
8111 template template parameters.
8113 Consider the example:
8114 template <class T> class A;
8115 template<template <class U> class TT> class B;
8117 For B<A>, PARM_TMPL is TT, while ARG_TMPL is A,
8118 and OUTER_ARGS contains A. */
8120 static int
8122 tree arg_tmpl,
8123 tsubst_flags_t complain,
8124 tree in_decl,
8125 tree outer_args)
8126 {
8140 {
8141 /* P0522R0: A template template-parameter P is at least as specialized as
8142 a template template-argument A if, given the following rewrite to two
8143 function templates, the function template corresponding to P is at
8144 least as specialized as the function template corresponding to A
8145 according to the partial ordering rules for function templates
8146 ([temp.func.order]). Given an invented class template X with the
8147 template parameter list of A (including default arguments):
8149 * Each of the two function templates has the same template parameters,
8150 respectively, as P or A.
8152 * Each function template has a single function parameter whose type is
8153 a specialization of X with template arguments corresponding to the
8154 template parameters from the respective function template where, for
8155 each template parameter PP in the template parameter list of the
8156 function template, a corresponding template argument AA is formed. If
8157 PP declares a parameter pack, then AA is the pack expansion
8158 PP... ([temp.variadic]); otherwise, AA is the id-expression PP.
8160 If the rewrite produces an invalid type, then P is not at least as
8161 specialized as A. */
8163 /* So coerce P's args to apply to A's parms, and then deduce between A's
8164 args and the converted args. If that succeeds, A is at least as
8165 specialized as P, so they match.*/
8171 /* PARM and ARG might be at different template depths, and we want to
8172 pass the right additional levels of args when coercing PARGS to
8173 ARG_PARMS in case we need to do any substitution into non-type
8174 template parameter types.
8176 OUTER_ARGS are not the right outer levels in this case, as they are
8177 the args we're building up for PARM, and for the coercion we want the
8178 args for ARG. If DECL_CONTEXT isn't set for a template template
8179 parameter, we can assume that it's in the current scope. */
8187 {
8192 /* Only use as many levels from the scope as needed
8193 (excluding the level of ARG). */
8197 else
8200 /* Add the arguments that appear at the levels of ARG. */
8207 }
8208 else
8214 {
8220 }
8221 }
8223 /* Determine whether we have a parameter pack at the end of the
8224 template template parameter's template parameter list. */
8226 {
8233 {
8247 }
8248 }
8254 /* Check all of the template parameters except the parameter pack at
8255 the end (if any). */
8257 {
8266 outer_args))
8269 }
8272 {
8273 /* Check each of the template parameters in the template
8274 argument against the template parameter pack at the end of
8275 the template template parameter. */
8282 {
8289 outer_args))
8291 }
8292 }
8295 }
8297 /* Verifies that the deduced template arguments (in TARGS) for the
8298 template template parameters (in TPARMS) represent valid bindings,
8299 by comparing the template parameter list of each template argument
8300 to the template parameter list of its corresponding template
8301 template parameter, in accordance with DR150. This
8302 routine can only be called after all template arguments have been
8303 deduced. It will return TRUE if all of the template template
8304 parameter bindings are okay, FALSE otherwise. */
8305 bool
8307 {
8311 /* We're dealing with template parms in this process. */
8317 {
8322 {
8327 {
8328 /* Look inside the argument pack. */
8331 }
8334 {
8336 /* Extract the next argument from the argument
8337 pack. */
8341 /* Look at the pattern of the pack expansion. */
8344 /* Extract the template parameters from the template
8345 argument. */
8349 /* Verify that we can coerce the template template
8350 parameters from the template argument to the template
8351 parameter. This requires an exact match. */
8353 && !coerce_template_template_parms
8355 targ,
8356 tf_none,
8357 tparm,
8358 targs))
8359 {
8362 }
8363 }
8364 }
8365 }
8367 out:
8371 }
8373 /* Since type attributes aren't mangled, we need to strip them from
8374 template type arguments. */
8376 tree
8378 {
8388 }
8390 /* And from inside dependent non-type arguments like sizeof(Type). */
8392 static tree
8394 {
8404 }
8406 /* A template declaration can be substituted for a constrained
8407 template template parameter only when the argument is no more
8408 constrained than the parameter. */
8410 static bool
8412 {
8415 /* For now, allow constrained template template arguments
8416 and unconstrained template template parameters. */
8420 /* If the template parameter is constrained, we need to rewrite its
8421 constraints in terms of the ARG's template parameters. This ensures
8422 that all of the template parameter types will have the same depth.
8424 Note that this is only valid when coerce_template_template_parm is
8425 true for the innermost template parameters of PARM and ARG. In other
8426 words, because coercion is successful, this conversion will be valid. */
8429 {
8439 }
8442 }
8444 // Convert a placeholder argument into a binding to the original
8445 // parameter. The original parameter is saved as the TREE_TYPE of
8446 // ARG.
8449 {
8452 }
8454 /* We can't fully resolve ARG given as a non-type template argument to TYPE,
8455 because one of them is dependent. But we need to represent the
8456 conversion for the benefit of cp_tree_equal. */
8458 static tree
8460 {
8461 /* Auto parms get no conversion. */
8464 /* We don't need or want to add this conversion now if we're going to use the
8465 argument for deduction. */
8477 }
8479 /* Convert the indicated template ARG as necessary to match the
8480 indicated template PARM. Returns the converted ARG, or
8481 error_mark_node if the conversion was unsuccessful. Error and
8482 warning messages are issued under control of COMPLAIN. This
8483 conversion is for the Ith parameter in the parameter list. ARGS is
8484 the full set of template arguments deduced so far. */
8486 static tree
8488 tree arg,
8489 tree args,
8490 tsubst_flags_t complain,
8492 tree in_decl)
8493 {
8494 tree orig_arg;
8495 tree val;
8501 /* Trivially convert placeholders. */
8510 {
8511 /* The template argument was the name of some
8512 member function. That's usually
8513 invalid, but static members are OK. In any
8514 case, grab the underlying fields/functions
8515 and issue an error later if required. */
8517 }
8525 /* When determining whether an argument pack expansion is a template,
8526 look at the pattern. */
8530 /* Deal with an injected-class-name used as a template template arg. */
8532 {
8535 {
8545 }
8546 }
8548 is_tmpl_type =
8564 {
8566 {
8570 }
8573 "to refer to a type member of a template parameter, "
8578 typename_type,
8579 complain);
8582 }
8584 {
8586 {
8588 {
8593 {
8594 /* The template argument is a type, but we're expecting
8595 an expression. */
8600 /* [temp.arg]/2: "In a template-argument, an ambiguity
8601 between a type-id and an expression is resolved to a
8602 type-id, regardless of the form of the corresponding
8603 template-parameter." So give the user a clue. */
8606 "for non-type template parameter is treated as "
8608 }
8612 else
8615 }
8616 }
8618 }
8620 {
8622 {
8629 else
8632 }
8634 }
8637 /* We already did the appropriate conversion when packing args. */
8640 {
8642 {
8644 /* The number of argument required is not known yet.
8645 Just accept it for now. */
8647 else
8648 {
8649 /* Strip alias templates that are equivalent to another
8650 template. */
8655 args))
8656 {
8659 /* TEMPLATE_TEMPLATE_PARM node is preferred over
8660 TEMPLATE_DECL. */
8662 {
8667 }
8668 }
8669 else
8670 {
8672 {
8679 }
8682 }
8684 // Check that the constraints are compatible before allowing the
8685 // substitution.
8688 {
8690 {
8696 }
8698 }
8699 }
8700 }
8701 else
8703 /* We only form one instance of each template specialization.
8704 Therefore, if we use a non-canonical variant (i.e., a
8705 typedef), any future messages referring to the type will use
8706 the typedef, which is confusing if those future uses do not
8707 themselves also use the typedef. */
8710 }
8711 else
8712 {
8717 /* We don't have enough levels of args to do any substitution. This
8720 {
8725 }
8726 else
8729 /* Perform array-to-pointer and function-to-pointer conversion
8730 as per [temp.param]/10. */
8736 /* Drop top-level cv-qualifiers on the substituted/deduced type of
8737 this non-type template parameter, as per [temp.param]/6. */
8745 /* We used to call digest_init here. However, digest_init
8746 will report errors, which we don't want when complain
8747 is zero. More importantly, digest_init will try too
8748 hard to convert things: for example, `0' should not be
8749 converted to pointer type at this point according to
8750 the standard. Accepting this is not merely an
8751 extension, since deciding whether or not these
8752 conversions can occur is part of determining which
8753 function template to call, or whether a given explicit
8754 argument specification is valid. */
8756 else
8757 {
8760 }
8771 {
8772 /* Reject template arguments that are references to built-in
8773 functions with no library fallbacks. */
8782 }
8785 {
8786 /* Strip typedefs from the SCOPE_REF. */
8789 complain);
8792 }
8793 }
8796 }
8798 /* Coerces the remaining template arguments in INNER_ARGS (from
8799 ARG_IDX to the end) into the parameter pack at PARM_IDX in PARMS.
8800 Returns the coerced argument pack. PARM_IDX is the position of this
8801 parameter in the template parameter list. ARGS is the original
8802 template argument list. */
8803 static tree
8806 tree args,
8807 tree inner_args,
8809 tree new_args,
8811 tree in_decl,
8812 tsubst_flags_t complain)
8813 {
8816 tree packed_args;
8817 tree argument_pack;
8824 {
8825 /* When the template parameter is a non-type template parameter pack
8826 or template template parameter pack whose type or template
8827 parameters use parameter packs, we know exactly how many arguments
8828 we are looking for. Build a vector of the instantiated decls for
8829 these template parameters in PACKED_PARMS. */
8830 /* We can't use make_pack_expansion here because it would interpret a
8831 _DECL as a use rather than a declaration. */
8845 /* If we're doing a partial instantiation of a member template,
8846 verify that all of the types used for the non-type
8847 template parameter pack are, in fact, valid for non-type
8848 template parameters. */
8851 {
8854 {
8859 }
8860 /* We don't know how many args we have yet, just
8861 use the unconverted ones for now. */
8863 }
8866 }
8867 /* Check if we have a placeholder pack, which indicates we're
8868 in the context of a introduction list. In that case we want
8869 to match this pack to the single placeholder. */
8873 {
8876 }
8877 else
8880 /* Convert the remaining arguments, which will be a part of the
8881 parameter pack "parm". */
8884 {
8890 {
8891 /* Once we've packed as many args as we have types, stop. */
8895 /* We don't know how many args we have yet, just
8896 use the unconverted ones for now. */
8898 else
8900 }
8903 {
8906 }
8907 else
8910 in_decl);
8914 }
8918 {
8923 }
8928 else
8929 {
8932 }
8939 }
8941 /* Returns the number of pack expansions in the template argument vector
8942 ARGS. */
8944 static int
8946 {
8951 {
8955 }
8957 }
8959 /* Convert all template arguments to their appropriate types, and
8960 return a vector containing the innermost resulting template
8961 arguments. If any error occurs, return error_mark_node. Error and
8962 warning messages are issued under control of COMPLAIN.
8964 If PARMS represents all template parameters levels, this function
8965 returns a vector of vectors representing all the resulting argument
8966 levels. Note that in this case, only the innermost arguments are
8967 coerced because the outermost ones are supposed to have been coerced
8968 already. Otherwise, if PARMS represents only (the innermost) vector
8969 of parameters, this function returns a vector containing just the
8970 innermost resulting arguments.
8972 If REQUIRE_ALL_ARGS is false, argument deduction will be performed
8973 for arguments not specified in ARGS. If REQUIRE_ALL_ARGS is true,
8974 arguments not specified in ARGS must have default arguments which
8975 we'll use to fill in ARGS. */
8977 tree
8979 tree args,
8980 tree in_decl,
8981 tsubst_flags_t complain,
8983 {
8985 tree orig_inner_args;
8986 tree inner_args;
8988 /* When used as a boolean value, indicates whether this is a
8989 variadic template parameter list. Since it's an int, we can also
8990 subtract it from nparms to get the number of non-variadic
8991 parameters. */
8996 /* Adjustment to nparms for fixed parameter packs. */
9001 /* Likewise for parameters with default arguments. */
9009 {
9011 {
9014 }
9016 }
9020 /* Determine if there are any parameter packs or default arguments. */
9022 {
9030 }
9033 /* If there are no parameters that follow a parameter pack, we need to
9034 expand any argument packs so that we can deduce a parameter pack from
9035 some non-packed args followed by an argument pack, as in variadic85.C.
9036 If there are such parameters, we need to leave argument packs intact
9037 so the arguments are assigned properly. This can happen when dealing
9038 with a nested class inside a partial specialization of a class
9039 template, as in variadic92.C, or when deducing a template parameter pack
9040 from a sub-declarator, as in variadic114.C. */
9044 /* Count any pack expansion args. */
9050 && require_all_args
9051 && !variadic_args_p
9054 {
9055 bad_nargs:
9057 {
9059 {
9063 }
9064 else
9071 }
9074 }
9075 /* We can't pass a pack expansion to a non-pack parameter of an alias
9076 template (DR 1430). */
9080 && variadic_args_p
9082 {
9084 {
9086 {
9092 {
9095 "pack expansion argument for non-pack parameter "
9097 else
9099 "pack expansion argument for non-pack parameter "
9103 }
9104 }
9106 found:;
9107 }
9109 }
9111 /* We need to evaluate the template arguments, even though this
9112 template-id may be nested within a "sizeof". */
9113 cp_evaluated ev;
9119 {
9120 tree arg;
9121 tree parm;
9123 /* Get the Ith template parameter. */
9127 {
9130 }
9132 /* Calculate the next argument. */
9135 else
9141 {
9142 /* Some arguments will be placed in the
9143 template parameter pack PARM. */
9150 {
9151 /* We don't know how many args we have yet, just use the
9152 unconverted (and still packed) ones for now. */
9156 }
9160 /* Store this argument. */
9162 {
9163 lost++;
9164 /* We are done with all of the arguments. */
9167 }
9168 else
9169 {
9173 {
9176 }
9177 }
9180 }
9182 {
9184 {
9185 /* "If every valid specialization of a variadic template
9186 requires an empty template parameter pack, the template is
9187 ill-formed, no diagnostic required." So check that the
9188 pattern works with this parameter. */
9193 in_decl);
9195 {
9200 }
9202 /* Recover from missing typename. */
9206 /* We don't know how many args we have yet, just
9207 use the unconverted ones for now. */
9211 }
9212 }
9214 {
9215 /* There must be a default arg in this case. */
9218 /* The position of the first default template argument,
9219 is also the number of non-defaulted arguments in NEW_INNER_ARGS.
9220 Record that. */
9224 }
9225 else
9229 {
9232 }
9234 {
9235 /* This can occur if there was an error in the template
9236 parameter list itself (which we would already have
9237 reported) that we are trying to recover from, e.g., a class
9238 template with a parameter list such as
9239 template<typename..., typename> (cpp0x/variadic150.C). */
9242 /* This can also happen with a fixed parameter pack (71834). */
9245 }
9246 else
9252 lost++;
9255 }
9258 {
9259 /* If we had fixed parameter packs, we didn't know how many arguments we
9260 actually needed earlier; now we do. */
9264 }
9267 {
9268 /* We had some pack expansion arguments that will only work if the packs
9269 are empty, but wait until instantiation time to complain.
9270 See variadic-ttp3.C. */
9272 /* Except that we can't provide empty packs to alias templates or
9273 concepts when there are no corresponding parameters. Basically,
9274 we can get here with this:
9276 template<typename T> concept C = true;
9278 template<typename... Args>
9279 requires C<Args...>
9280 void f();
9282 When parsing C<Args...>, we try to form a concept check of
9283 C<?, Args...>. Without the extra check for substituting an empty
9284 pack past the last parameter, we can accept the check as valid.
9286 FIXME: This may be valid for alias templates (but I doubt it).
9288 FIXME: The error could be better also. */
9290 {
9295 }
9306 }
9309 {
9312 }
9319 }
9321 /* Returns true if T is a wrapper to make a C++20 template parameter
9322 object const. */
9324 static bool
9326 {
9332 }
9334 /* Returns 1 if template args OT and NT are equivalent. */
9336 int
9338 {
9351 /* DR 1558: Don't treat an alias template specialization with dependent
9352 arguments as equivalent to its underlying type when used as a template
9353 argument; we need them to be distinct so that we substitute into the
9354 specialization arguments at instantiation time. And aliases can't be
9355 equivalent without being ==, so we don't need to look any deeper.
9357 During partial ordering, however, we need to treat them normally so we can
9358 order uses of the same alias with different cv-qualification (79960). */
9364 /* For member templates */
9377 {
9381 }
9382 else
9383 {
9384 /* Try to treat a template non-type argument that has been converted
9385 to the parameter type as equivalent to one that hasn't yet. */
9399 }
9400 }
9402 /* Returns true iff the OLDARGS and NEWARGS are in fact identical sets of
9403 template arguments. Returns false otherwise, and updates OLDARG_PTR and
9404 NEWARG_PTR with the offending arguments if they are non-NULL. */
9406 bool
9409 {
9420 {
9425 {
9431 }
9432 }
9434 }
9436 static bool
9438 {
9443 }
9445 /* Implement a freelist interface for objects of type T.
9447 Head is a separate object, rather than a regular member, so that we
9448 can define it as a GTY deletable pointer, which is highly
9449 desirable. A data member could be declared that way, but then the
9450 containing object would implicitly get GTY((user)), which would
9451 prevent us from instantiating freelists as global objects.
9452 Although this way we can create freelist global objects, they're
9453 such thin wrappers that instantiating temporaries at every use
9454 loses nothing and saves permanent storage for the freelist object.
9456 Member functions next, anew, poison and reinit have default
9457 implementations that work for most of the types we're interested
9458 in, but if they don't work for some type, they should be explicitly
9459 specialized. See the comments before them for requirements, and
9460 the example specializations for the tree_list_freelist. */
9462 class freelist
9463 {
9464 /* Return the next object in a chain. We could just do type
9465 punning, but if we access the object with its underlying type, we
9466 avoid strict-aliasing trouble. This needs only work between
9467 poison and reinit. */
9470 /* Return a newly allocated, uninitialized or minimally-initialized
9471 object of type T. Any initialization performed by anew should
9472 either remain across the life of the object and the execution of
9473 poison, or be redone by reinit. */
9476 /* Optionally scribble all over the bits holding the object, so that
9477 they become (mostly?) uninitialized memory. This is called while
9478 preparing to make the object part of the free list. */
9483 #ifdef ENABLE_GC_CHECKING
9484 /* Poison the data, to indicate the data is garbage. */
9487 #endif
9488 /* Let valgrind know the object is free. */
9491 /* Let valgrind know the next portion of the object is available,
9492 but uninitialized. */
9494 }
9496 /* Bring an object that underwent at least one lifecycle after anew
9497 and before the most recent free and poison, back to a usable
9498 state, reinitializing whatever is needed for it to be
9499 functionally equivalent to an object just allocated and returned
9500 by anew. This may poison or clear the next field, used by
9501 freelist housekeeping after poison was called. */
9505 #ifdef ENABLE_GC_CHECKING
9507 #endif
9508 /* Let valgrind know the entire object is available, but
9509 uninitialized. */
9511 }
9513 /* Reference a GTY-deletable pointer that points to the first object
9514 in the free list proper. */
9517 /* Construct a freelist object chaining objects off of HEAD. */
9520 /* Add OBJ to the free object list. The former head becomes OBJ's
9521 successor. */
9523 {
9527 }
9529 /* Take an object from the free list, if one is available, or
9530 allocate a new one. Objects taken from the free list should be
9531 regarded as filled with garbage, except for bits that are
9532 configured to be preserved across free and alloc. */
9534 {
9536 {
9541 }
9542 else
9544 }
9545 };
9547 /* Explicitly specialize the interfaces for freelist<tree_node>: we
9548 want to allocate a TREE_LIST using the usual interface, and ensure
9549 TREE_CHAIN remains functional. Alas, we have to duplicate a bit of
9550 build_tree_list logic in reinit, so this could go out of sync. */
9554 {
9556 }
9558 inline tree
9560 {
9562 }
9566 {
9572 #ifdef ENABLE_GC_CHECKING
9575 /* Poison the data, to indicate the data is garbage. */
9578 #endif
9579 /* Let valgrind know the object is free. */
9581 /* But we still want to use the TREE_CODE and TREE_CHAIN parts. */
9585 #ifdef ENABLE_GC_CHECKING
9587 /* Keep TREE_CHAIN functional. */
9589 #else
9591 #endif
9592 }
9596 {
9599 #ifdef ENABLE_GC_CHECKING
9603 #endif
9605 /* Let valgrind know the entire object is available, but
9606 uninitialized. */
9609 #ifdef ENABLE_GC_CHECKING
9611 #else
9614 #endif
9616 }
9618 /* Point to the first object in the TREE_LIST freelist. */
9620 /* Return the/an actual TREE_LIST freelist. */
9623 {
9625 }
9627 /* Point to the first object in the tinst_level freelist. */
9629 /* Return the/an actual tinst_level freelist. */
9632 {
9634 }
9636 /* Point to the first object in the pending_template freelist. */
9638 /* Return the/an actual pending_template freelist. */
9641 {
9643 }
9645 /* Build the TREE_LIST object out of a split list, store it
9646 permanently, and return it. */
9647 tree
9649 {
9658 }
9662 /* Increment OBJ's refcount unless it is already infinite. */
9665 {
9669 }
9671 /* Release storage for OBJ and node, if it's a TREE_LIST. */
9672 void
9674 {
9678 }
9680 /* Decrement OBJ's refcount if not infinite. If it reaches zero, release
9681 OBJ's DECL and OBJ, and start over with the tinst_level object that
9682 used to be referenced by OBJ's NEXT. */
9683 static void
9685 {
9689 {
9693 }
9694 }
9696 /* Modify PTR so that it points to OBJ, adjusting the refcounts of OBJ
9697 and of the former PTR. Omitting the second argument is equivalent
9698 to passing (T*)NULL; this is allowed because passing the
9699 zero-valued integral constant NULL confuses type deduction and/or
9700 overload resolution. */
9702 static void
9704 {
9708 }
9710 static void
9712 {
9722 /* We are called both from instantiate_decl, where we've already had a
9723 tinst_level pushed, and instantiate_template, where we haven't.
9724 Compensate. */
9726 level = !current_tinst_level
9738 else
9747 }
9750 /* Return a TEMPLATE_ID_EXPR corresponding to the indicated FNS and
9751 ARGLIST. Valid choices for FNS are given in the cp-tree.def
9752 documentation for TEMPLATE_ID_EXPR. */
9754 tree
9756 {
9763 {
9766 }
9769 {
9772 unknown_type_node,
9774 arglist);
9776 }
9779 }
9781 /* Within the scope of a template class S<T>, the name S gets bound
9782 (in build_self_reference) to a TYPE_DECL for the class, not a
9783 TEMPLATE_DECL. If DECL is a TYPE_DECL for current_class_type,
9784 or one of its enclosing classes, and that type is a template,
9785 return the associated TEMPLATE_DECL. Otherwise, the original
9786 DECL is returned.
9788 Also handle the case when DECL is a TREE_LIST of ambiguous
9789 injected-class-names from different bases. */
9791 tree
9793 {
9797 /* DR 176: A lookup that finds an injected-class-name (10.2
9798 [class.member.lookup]) can result in an ambiguity in certain cases
9799 (for example, if it is found in more than one base class). If all of
9800 the injected-class-names that are found refer to specializations of
9801 the same class template, and if the name is followed by a
9802 template-argument-list, the reference refers to the class template
9803 itself and not a specialization thereof, and is not ambiguous. */
9805 {
9808 {
9814 }
9817 else
9819 }
9825 }
9827 /* Given an IDENTIFIER_NODE (or type TEMPLATE_DECL) and a chain of
9828 parameters, find the desired type.
9830 D1 is the PTYPENAME terminal, and ARGLIST is the list of arguments.
9832 IN_DECL, if non-NULL, is the template declaration we are trying to
9833 instantiate.
9835 If ENTERING_SCOPE is nonzero, we are about to enter the scope of
9836 the class we are looking up.
9838 Issue error and warning messages under control of COMPLAIN.
9840 If the template class is really a local class in a template
9841 function, then the FUNCTION_CONTEXT is the function in which it is
9842 being instantiated.
9844 ??? Note that this function is currently called *twice* for each
9845 template-id: the first time from the parser, while creating the
9846 incomplete type (finish_template_type), and the second type during the
9847 real instantiation (instantiate_template_class). This is surely something
9848 that we want to avoid. It also causes some problems with argument
9849 coercion (see convert_nontype_argument for more information on this). */
9851 tree
9854 {
9858 tree t;
9861 spec_entry elt;
9862 hashval_t hash;
9865 {
9869 else
9870 {
9877 }
9878 }
9880 {
9883 /* If we are declaring a constructor, say A<T>::A<T>, we will get
9884 an implicit typename for the second A. Deal with it. */
9889 {
9892 }
9893 }
9896 {
9899 }
9901 {
9904 }
9906 {
9909 }
9911 /* Issue an error message if we didn't find a template. */
9913 {
9917 }
9920 /* Make sure it's a user visible template, if it was named by
9921 the user. */
9924 {
9926 {
9930 }
9932 }
9936 /* An alias that just changes the name of a template is equivalent to the
9937 other template, so if any of the arguments are pack expansions, strip
9938 the alias to avoid problems with a pack expansion passed to a non-pack
9939 alias template parameter (DR 1430). */
9944 {
9945 tree parm;
9954 }
9955 else
9956 {
9958 tree gen_tmpl;
9959 tree type_decl;
9967 /* An error occurred while building the template TEMPL, and a
9968 diagnostic has most certainly been emitted for that
9969 already. Let's propagate that error. */
9981 {
9982 /* We've been given an incomplete set of template arguments.
9983 For example, given:
9985 template <class T> struct S1 {
9986 template <class U> struct S2 {};
9987 template <class U> struct S2<U*> {};
9988 };
9990 we will be called with an ARGLIST of `U*', but the
9991 TEMPLATE will be `template <class T> template
9992 <class U> struct S1<T>::S2'. We must fill in the missing
9993 arguments. */
9997 }
9999 /* Now we should have enough arguments. */
10002 /* From here on, we're only interested in the most general
10003 template. */
10005 /* Shortcut looking up the current class scope again. */
10009 {
10020 }
10022 /* Calculate the BOUND_ARGS. These will be the args that are
10023 actually tsubst'd into the definition to create the
10024 instantiation. */
10029 /* We were unable to bind the arguments. */
10032 /* In the scope of a template class, explicit references to the
10033 template class refer to the type of the template, not any
10034 instantiation of it. For example, in:
10036 template <class T> class C { void f(C<T>); }
10038 the `C<T>' is just the same as `C'. Outside of the
10039 class, however, such a reference is an instantiation. */
10043 {
10048 }
10050 /* If we already have this specialization, return it. */
10060 /* If the template's constraints are not satisfied,
10061 then we cannot form a valid type.
10063 Note that the check is deferred until after the hash
10064 lookup. This prevents redundant checks on previously
10065 instantiated specializations. */
10069 {
10071 {
10072 auto_diagnostic_group d;
10075 }
10077 }
10081 /* If the deduced arguments are invalid, then the binding
10082 failed. */
10086 complain))
10093 /* This occurs when the user has tried to define a tagged type
10094 in a scope that forbids it. We emitted an error during the
10095 parse. We didn't complete the bail out then, so here we
10096 are. */
10101 {
10103 /* If the context of the partially instantiated template is
10104 already non-dependent, then we might as well use it. */
10106 else
10107 {
10110 /* Try completing the enclosing context if it's not already so. */
10113 {
10116 {
10117 /* Completion could have caused us to register the desired
10118 specialization already, so check the table again. */
10122 }
10123 }
10124 }
10125 }
10126 else
10135 /* Create the type. */
10137 {
10138 /* The user referred to a specialization of an alias
10139 template represented by GEN_TMPL.
10141 [temp.alias]/2 says:
10143 When a template-id refers to the specialization of an
10144 alias template, it is equivalent to the associated
10145 type obtained by substitution of its
10146 template-arguments for the template-parameters in the
10147 type-id of the alias template. */
10150 /* Note that the call above (by indirectly calling
10151 register_specialization in tsubst_decl) registers the
10152 TYPE_DECL representing the specialization of the alias
10153 template. So next time someone substitutes ARGLIST for
10154 the template parms into the alias template (GEN_TMPL),
10155 she'll get that TYPE_DECL back. */
10159 }
10161 {
10163 {
10174 }
10175 else
10176 {
10177 /* We don't want to call start_enum for this type, since
10178 the values for the enumeration constants may involve
10179 template parameters. And, no one should be interested
10180 in the enumeration constants for such a type. */
10183 }
10187 }
10189 {
10190 /* Lambda closures are regenerated in tsubst_lambda_expr, not
10191 instantiated here. */
10199 /* A local class. Make sure the decl gets registered properly. */
10206 /* This instantiation is another name for the primary
10207 template type. Set the TYPE_CANONICAL field
10208 appropriately. */
10212 }
10213 else
10216 /* If we called start_enum or pushtag above, this information
10217 will already be set up. */
10220 {
10227 }
10230 /* Although GEN_TMPL is the TEMPLATE_DECL, it has the same value
10231 of export flag. We want to propagate this because it might
10232 be a friend declaration that pushes a new hidden binding. */
10236 {
10242 {
10245 }
10246 }
10250 {
10254 {
10255 tree attributes
10263 }
10264 }
10266 /* Let's consider the explicit specialization of a member
10267 of a class template specialization that is implicitly instantiated,
10268 e.g.:
10269 template<class T>
10270 struct S
10271 {
10272 template<class U> struct M {}; //#0
10273 };
10275 template<>
10276 template<>
10277 struct S<int>::M<char> //#1
10278 {
10279 int i;
10280 };
10281 [temp.expl.spec]/4 says this is valid.
10283 In this case, when we write:
10284 S<int>::M<char> m;
10286 M is instantiated from the CLASSTYPE_TI_TEMPLATE of #1, not from
10287 the one of #0.
10289 When we encounter #1, we want to store the partial instantiation
10290 of M (template<class T> S<int>::M<T>) in its CLASSTYPE_TI_TEMPLATE.
10292 For all cases other than this "explicit specialization of member of a
10293 class template", we just want to store the most general template into
10294 the CLASSTYPE_TI_TEMPLATE of M.
10296 This case of "explicit specialization of member of a class template"
10297 only happens when:
10298 1/ the enclosing class is an instantiation of, and therefore not
10299 the same as, the context of the most general template, and
10300 2/ we aren't looking at the partial instantiation itself, i.e.
10301 the innermost arguments are not the same as the innermost parms of
10302 the most general template.
10304 So it's only when 1/ and 2/ happens that we want to use the partial
10305 instantiation of the member template in lieu of its most general
10306 template. */
10310 /* the enclosing class must be an instantiation... */
10313 {
10317 tree partial_inst_args =
10324 use_partial_inst_tmpl =
10325 /*...and we must not be looking at the partial instantiation
10326 itself. */
10328 partial_inst_args);
10329 }
10332 /* This case is easy; there are no member templates involved. */
10334 else
10335 {
10336 /* This is a full instantiation of a member template. Find
10337 the partial instantiation of which this is an instance. */
10339 /* Temporarily reduce by one the number of levels in the ARGLIST
10340 so as to avoid comparing the last set of arguments. */
10342 /* We don't use COMPLAIN in the following call because this isn't
10343 the immediate context of deduction. For instance, tf_partial
10344 could be set here as we might be at the beginning of template
10345 argument deduction when any explicitly specified template
10346 arguments are substituted into the function type. tf_partial
10347 could lead into trouble because we wouldn't find the partial
10348 instantiation that might have been created outside tf_partial
10349 context, because the levels of template parameters wouldn't
10350 match, because in a tf_partial context, tsubst doesn't reduce
10351 TEMPLATE_PARM_LEVEL. */
10354 /* FOUND is either a proper class type, or an alias
10355 template specialization. In the later case, it's a
10356 TYPE_DECL, resulting from the substituting of arguments
10357 for parameters in the TYPE_DECL of the alias template
10358 done earlier. So be careful while getting the template
10359 of FOUND. */
10361 ? found
10368 {
10369 /* If this partial instantiation is specialized, we want to
10370 use it for hash table lookup. */
10374 }
10375 }
10377 /* Build template info for the new specialization. */
10387 /* Note this use of the partial instantiation so we can check it
10388 later in maybe_process_partial_specialization. */
10396 /* Now that the type has been registered on the instantiations
10397 list, we set up the enumerators. Because the enumeration
10398 constants may involve the enumeration type itself, we make
10399 sure to register the type first, and then create the
10400 constants. That way, doing tsubst_expr for the enumeration
10401 constants won't result in recursive calls here; we'll find
10402 the instantiation and exit above. */
10406 /* If the type makes use of template parameters, the
10407 code that generates debugging information will crash. */
10410 /* Possibly limit visibility based on template args. */
10417 }
10418 }
10420 /* Return a TEMPLATE_ID_EXPR for the given variable template and ARGLIST. */
10422 tree
10424 {
10435 /* The type of the expression is NULL_TREE since the template-id could refer
10436 to an explicit or partial specialization. */
10438 }
10440 /* Instantiate a variable declaration from a TEMPLATE_ID_EXPR if it's
10441 not dependent. */
10443 tree
10445 {
10449 /* If the template or arguments are dependent, then we
10450 can't resolve the TEMPLATE_ID_EXPR yet. */
10456 {
10458 {
10459 auto_diagnostic_group d;
10462 }
10464 }
10467 }
10469 /* Construct a TEMPLATE_ID_EXPR for the given variable template TEMPL having
10470 TARGS template args, and instantiate it if it's not dependent. */
10472 tree
10474 tsubst_flags_t complain)
10475 {
10482 }
10484 /* If the set of template parameters PARMS contains a template parameter
10485 at the given LEVEL and INDEX, then return this parameter. Otherwise
10486 return NULL_TREE. */
10488 static tree
10490 {
10499 }
10501 /* Return the TREE_LIST for the template parameter from PARMS that positionally
10502 corresponds to the template parameter PARM, or else return NULL_TREE. */
10504 static tree
10506 {
10510 }
10512 /* As above, but pull out the actual parameter. */
10514 static tree
10516 {
10522 /* As in template_parm_to_arg. */
10525 else
10530 }
10531 \f
10532 struct pair_fn_data
10533 {
10534 tree_fn_t fn;
10535 tree_fn_t any_fn;
10537 /* True when we should also visit template parameters that occur in
10538 non-deduced contexts. */
10541 };
10543 /* Called from for_each_template_parm via walk_tree. */
10545 static tree
10547 {
10554 #define WALK_SUBTREE(NODE) \
10555 do \
10556 { \
10557 result = for_each_template_parm (NODE, fn, data, pfd->visited, \
10558 pfd->include_nondeduced_p, \
10559 pfd->any_fn); \
10560 if (result) goto out; \
10561 } \
10562 while (0)
10572 {
10576 /* Fall through. */
10582 else
10592 /* Since we're not going to walk subtrees, we have to do this
10593 explicitly here. */
10595 /* Fall through. */
10598 /* Check the return type. */
10601 /* Check the parameter types. Since default arguments are not
10602 instantiated until they are needed, the TYPE_ARG_TYPES may
10603 contain expressions that involve template parameters. But,
10604 no-one should be looking at them yet. And, once they're
10605 instantiated, they don't contain template parameters, so
10606 there's no point in looking at them then, either. */
10607 {
10608 tree parm;
10613 /* Since we've already handled the TYPE_ARG_TYPES, we don't
10614 want walk_tree walking into them itself. */
10616 }
10619 {
10623 }
10639 {
10642 }
10665 /* Record template parameters such as `T' inside `TT<T>'. */
10667 /* Fall through. */
10679 /* A template template parameter is encountered. */
10683 /* Already substituted template template parameter */
10688 /* A template-id in a TYPENAME_TYPE might be a deduced context after
10689 partial instantiation. */
10696 /* If there's no type, then this thing must be some expression
10697 involving template parameters. */
10707 /* These are non-deduced contexts. */
10729 }
10731 #undef WALK_SUBTREE
10733 /* We didn't find any template parameters we liked. */
10734 out:
10736 }
10738 /* For each TEMPLATE_TYPE_PARM, TEMPLATE_TEMPLATE_PARM,
10739 BOUND_TEMPLATE_TEMPLATE_PARM or TEMPLATE_PARM_INDEX in T,
10740 call FN with the parameter and the DATA.
10741 If FN returns nonzero, the iteration is terminated, and
10742 for_each_template_parm returns 1. Otherwise, the iteration
10743 continues. If FN never returns a nonzero value, the value
10744 returned by for_each_template_parm is 0. If FN is NULL, it is
10745 considered to be the function which always returns 1.
10747 If INCLUDE_NONDEDUCED_P, then this routine will also visit template
10748 parameters that occur in non-deduced contexts. When false, only
10749 visits those template parameters that can be deduced. */
10751 static tree
10755 tree_fn_t any_fn)
10756 {
10758 tree result;
10760 /* Set up. */
10766 /* Walk the tree. (Conceptually, we would like to walk without
10767 duplicates, but for_each_template_parm_r recursively calls
10768 for_each_template_parm, so we would need to reorganize a fair
10769 bit to use walk_tree_without_duplicates, so we keep our own
10770 visited list.) */
10773 else
10776 for_each_template_parm_r,
10780 /* Clean up. */
10782 {
10785 }
10788 }
10790 struct find_template_parameter_info
10791 {
10795 {}
10801 tree ctx_parms;
10808 };
10810 /* Appends the declaration of T to the list in DATA. */
10812 static int
10814 {
10817 /* Template parameters declared within the expression are not part of
10818 the parameter mapping. For example, in this concept:
10820 template<typename T>
10821 concept C = requires { <expr> } -> same_as<int>;
10823 the return specifier same_as<int> declares a new decltype parameter
10824 that must not be part of the parameter mapping. The same is true
10825 for generic lambda parameters, lambda template parameters, etc. */
10833 /* We want the underlying TEMPLATE_TEMPLATE_PARM, not the
10834 BOUND_TEMPLATE_TEMPLATE_PARM itself. */
10837 /* This template parameter might be an argument to a cached dependent
10838 specalization that was formed earlier inside some other template, in
10839 which case the parameter is not among the ones that are in-scope.
10840 Look in CTX_PARMS to find the corresponding in-scope template
10841 parameter, and use it instead. */
10845 /* Arguments like const T yield parameters like const T. This means that
10846 a template-id like X<T, const T> would yield two distinct parameters:
10847 T and const T. Adjust types to their unqualified versions. */
10851 {
10852 /* Append T to PARM_LIST. */
10856 }
10858 /* Verify the parameter we found has a valid index. */
10860 {
10866 }
10869 }
10871 /* Ensure that we recursively examine certain terms that are not normally
10872 visited in for_each_template_parm_r. */
10874 static int
10876 {
10879 #define WALK_SUBTREE(NODE) \
10880 do \
10881 { \
10882 for_each_template_parm (NODE, keep_template_parm, data, \
10883 &ftpi->visited, true, \
10884 any_template_parm_r); \
10885 } \
10886 while (0)
10888 /* A mention of a member alias/typedef is a use of all of its template
10889 arguments, including those from the enclosing class, so we don't use
10890 alias_template_specialization_p here. */
10896 {
10898 /* Type constraints of a placeholder type may contain parameters. */
10905 /* Search through references to variable templates. */
10915 /* If T is a member template that shares template parameters with
10916 ctx_parms, we need to mark all those parameters for mapping.
10917 To that end, it should suffice to just walk the DECL_CONTEXT of
10918 the template (assuming the template is not overly general). */
10923 {
10924 /* Look in the parms and body. */
10928 }
10933 /* The conversion-type-id of a conversion operator may be dependent. */
10944 }
10946 /* Keep walking. */
10948 }
10950 /* Look through T for template parameters. */
10952 tree
10954 {
10957 any_template_parm_r);
10958 }
10960 /* As above, but also recursively look into the default arguments of template
10961 parameters we found. Used for alias CTAD. */
10963 tree
10965 {
10968 /* Since newly found parms are added to the end of the list, we
10969 can just walk it until we reach the end. */
10971 {
10976 }
10978 }
10980 /* True if PARM was found by a previous call to find_in. PARM can be a
10981 TREE_LIST, a DECL_TEMPLATE_PARM_P, or a TEMPLATE_PARM_P. */
10983 bool
10985 {
10990 else
10994 }
10996 /* Returns a list of unique template parameters found within T, where CTX_PARMS
10997 are the template parameters in scope. */
10999 tree
11001 {
11008 }
11010 /* Returns true if T depends on any template parameter. */
11012 bool
11014 {
11018 /* Namespaces can't depend on any template parameters. */
11034 else
11036 }
11038 /* Returns true if T depends on any template parameter with level LEVEL. */
11040 bool
11042 {
11045 }
11047 /* Returns true if the signature of DECL depends on any template parameter from
11048 its enclosing class. */
11050 static bool
11052 {
11056 else
11065 {
11068 {
11073 template_parm_outer_level,
11083 }
11084 }
11088 }
11090 /* Returns true if the constraints of DECL depend on any template parameters
11091 from its enclosing scope. */
11093 bool
11095 {
11102 {
11105 else
11107 }
11113 }
11115 /* Returns TRUE iff INST is an instantiation we don't need to do in an
11116 ill-formed translation unit, i.e. a variable or function that isn't
11117 usable in a constant expression. */
11121 {
11127 }
11129 /* Returns TRUE iff we should refuse to instantiate DECL because it's
11130 neglectable and instantiated from within an erroneous instantiation. */
11132 static bool
11134 {
11140 /* Avoid instantiating members of an ill-formed class. */
11141 bool refuse
11146 {
11151 }
11154 {
11155 /* Don't warn about it not being defined. */
11157 tree clone;
11160 }
11162 }
11170 /* We're starting to instantiate D; record the template instantiation context
11171 at LOC for diagnostics and to restore it later. */
11173 bool
11175 {
11179 {
11180 /* Tell error.cc not to try to instantiate any templates. */
11183 "template instantiation depth exceeds maximum of %d"
11185 max_tinst_depth);
11187 }
11189 /* If the current instantiation caused problems, don't let it instantiate
11190 anything else. Do allow deduction substitution and decls usable in
11191 constant expressions. */
11193 {
11194 /* Avoid no_linkage_errors and unused function (and all other)
11195 warnings for this decl. */
11198 }
11200 /* When not -quiet, dump template instantiations other than functions, since
11201 announce_function will take care of those. */
11223 }
11225 /* We're starting substitution of TMPL<ARGS>; record the template
11226 substitution context for diagnostics and to restore it later. */
11228 bool
11230 {
11232 }
11234 /* We're starting to instantiate D; record INPUT_LOCATION and the
11235 template instantiation context for diagnostics and to restore it
11236 later. */
11238 bool
11240 {
11242 }
11244 /* Likewise, but record LOC as the program location. */
11246 bool
11248 {
11251 }
11253 /* We're done instantiating this template; return to the instantiation
11254 context. */
11256 void
11258 {
11259 /* Restore the filename and line number stashed away when we started
11260 this instantiation. */
11264 }
11266 /* We're instantiating a deferred template; restore the template
11267 instantiation context in which the instantiation was requested, which
11268 is one step out from LEVEL. Return the corresponding DECL or TYPE. */
11270 static tree
11272 {
11284 }
11286 /* Returns the TINST_LEVEL which gives the original instantiation
11287 context. */
11291 {
11297 }
11299 /* True iff T is a friend function declaration that is not itself a template
11300 and is not defined in a class template. */
11302 bool
11304 {
11307 {
11311 /* DECL_FRIEND_CONTEXT is set for a friend defined in class. */
11314 /* Non-templated friends in a class template are still represented with a
11315 TEMPLATE_DECL; check that its primary template is the befriending
11316 class. Note that DECL_PRIMARY_TEMPLATE is null for
11317 template <class T> friend A<T>::f(); */
11321 }
11322 else
11324 }
11326 /* DECL is a friend FUNCTION_DECL or TEMPLATE_DECL. ARGS is the
11327 vector of template arguments, as for tsubst.
11329 Returns an appropriate tsubst'd friend declaration. */
11331 static tree
11333 {
11334 tree new_friend;
11339 /* This was a friend declared with an explicit template
11340 argument list, e.g.:
11342 friend void f<>(T);
11344 to indicate that f was a template instantiation, not a new
11345 function declaration. Now, we have to figure out what
11346 instantiation of what template. */
11347 {
11349 tree new_args;
11350 tree tmpl;
11353 /* Friend functions are looked up in the containing namespace scope.
11354 We must enter that scope, to avoid finding member functions of the
11355 current class with same name. */
11369 tsk_none);
11371 }
11377 /* The NEW_FRIEND will look like an instantiation, to the
11378 compiler, but is not an instantiation from the point of view of
11379 the language. For example, we might have had:
11381 template <class T> struct S {
11382 template <class U> friend void f(T, U);
11383 };
11385 Then, in S<int>, template <class U> void f(int, U) is not an
11386 instantiation of anything. */
11390 {
11396 /* Substitute TEMPLATE_PARMS_CONSTRAINTS so that parameter levels will
11397 match in decls_match. */
11402 {
11404 /* As well as each TEMPLATE_PARM_CONSTRAINTS. */
11406 tf_warning_or_error);
11407 }
11408 }
11410 /* The mangled name for the NEW_FRIEND is incorrect. The function
11411 is not a template instantiation and should not be mangled like
11412 one. Therefore, we forget the mangling here; we'll recompute it
11413 later if we need it. */
11415 {
11418 }
11421 {
11422 tree old_decl;
11423 tree ns;
11425 /* We must save some information from NEW_FRIEND before calling
11426 duplicate decls since that function will free NEW_FRIEND if
11427 possible. */
11431 (new_friend_template_info
11438 {
11439 /* This declaration is a `primary' template. */
11444 }
11446 /* Inside pushdecl_namespace_level, we will push into the
11447 current namespace. However, the friend function should go
11448 into the namespace of the template. */
11458 {
11459 /* This new friend declaration matched an existing
11460 declaration. For example, given:
11462 template <class T> void f(T);
11463 template <class U> class C {
11464 template <class T> friend void f(T) {}
11465 };
11467 the friend declaration actually provides the definition
11468 of `f', once C has been instantiated for some type. So,
11469 old_decl will be the out-of-class template declaration,
11470 while new_friend is the in-class definition.
11472 But, if `f' was called before this point, the
11473 instantiation of `f' will have DECL_TI_ARGS corresponding
11474 to `T' but not to `U', references to which might appear
11475 in the definition of `f'. Previously, the most general
11476 template for an instantiation of `f' was the out-of-class
11477 version; now it is the in-class version. Therefore, we
11478 run through all specialization of `f', adding to their
11479 DECL_TI_ARGS appropriately. In particular, they need a
11480 new set of outer arguments, corresponding to the
11481 arguments for this class instantiation.
11483 The same situation can arise with something like this:
11485 friend void f(int);
11486 template <class T> class C {
11487 friend void f(T) {}
11488 };
11490 when `C<int>' is instantiated. Now, `f(int)' is defined
11491 in the class. */
11494 /* On the other hand, if the in-class declaration does
11495 *not* provide a definition, then we don't want to alter
11496 existing definitions. We can just leave everything
11497 alone. */
11498 ;
11499 else
11500 {
11504 /* Overwrite whatever template info was there before, if
11505 any, with the new template information pertaining to
11506 the declaration. */
11510 {
11511 /* We should have called reregister_specialization in
11512 duplicate_decls. */
11517 /* Instantiate it if the global has already been used. */
11521 }
11522 else
11523 {
11524 tree t;
11526 /* Indicate that the old function template is a partial
11527 instantiation. */
11535 /* Reassign any specializations already in the hash table
11536 to the new more general template, and add the
11537 additional template args. */
11541 {
11543 spec_entry elt;
11555 register_specialization
11558 }
11560 }
11561 }
11563 /* The information from NEW_FRIEND has been merged into OLD_DECL
11564 by duplicate_decls. */
11566 }
11568 /* We've just introduced a namespace-scope function in the purview
11569 without necessarily having opened the enclosing namespace, so
11570 make sure the namespace is in the purview now too. */
11575 }
11576 else
11577 {
11581 /* In the code
11582 template <class T> class C {
11583 template <class U> friend void C1<U>::f (); // case 1
11584 friend void C2<T>::f (); // case 2
11585 };
11586 we only need to make sure CONTEXT is a complete type for
11587 case 2. To distinguish between the two cases, we note that
11588 CONTEXT of case 1 remains dependent type after tsubst while
11589 this isn't true for case 2. */
11599 {
11601 /* do_friend adds the TEMPLATE_DECL for any member friend
11602 template even if it isn't a member template, i.e.
11603 template <class T> friend A<T>::f();
11604 Look through it in that case. */
11608 /* Check to see that the declaration is really present, and,
11609 possibly obtain an improved declaration. */
11614 }
11615 }
11618 }
11620 /* FRIEND_TMPL is a friend TEMPLATE_DECL. ARGS is the vector of
11621 template arguments, as for tsubst.
11623 Returns an appropriate tsubst'd friend type or error_mark_node on
11624 failure. */
11626 static tree
11628 {
11629 tree tmpl;
11632 {
11635 }
11640 else
11641 {
11644 }
11650 {
11651 /* The friend template has already been declared. Just
11652 check to see that the declarations match, and install any new
11653 default parameters. We must tsubst the default parameters,
11654 of course. We only need the innermost template parameters
11655 because that is all that redeclare_class_template will look
11656 at. */
11659 {
11663 tf_warning_or_error);
11673 }
11674 }
11675 else
11676 {
11677 /* The friend template has not already been declared. In this
11678 case, the instantiation of the template class will cause the
11679 injection of this template into the namespace scope. */
11683 {
11684 /* The new TMPL is not an instantiation of anything, so we
11685 forget its origins. We don't reset CLASSTYPE_TI_TEMPLATE
11686 for the new type because that is supposed to be the
11687 corresponding template decl, i.e., TMPL. */
11694 /* Substitute into and set the constraints on the new declaration. */
11696 {
11704 }
11706 /* Inject this template into the enclosing namspace scope. */
11708 }
11709 }
11713 else
11717 }
11719 /* Returns zero if TYPE cannot be completed later due to circularity.
11720 Otherwise returns one. */
11722 static int
11724 {
11734 else
11736 }
11741 /* Instantiate the contract statement. */
11743 static tree
11745 tree in_decl)
11746 {
11752 /* Rebuild the result variable. */
11754 {
11762 /* Make sure the postcondition is valid. */
11768 /* Make the variable available for lookup. */
11770 }
11772 /* Instantiate the condition. If the return type is undeduced, process
11773 the expression as if inside a template to avoid spurious type errors. */
11783 /* And the comment. */
11788 }
11790 /* Update T by instantiating its contract attribute. */
11792 static void
11795 {
11796 /* For non-specializations, adjust the current declaration to the most general
11797 version of in_decl. Because we defer the instantiation of contracts as long
11798 as possible, they are still written in terms of the parameters (and return
11799 type) of the most general template. */
11806 /* Get the contract to be instantiated. */
11809 /* Use the complete set of template arguments for instantiation. The
11810 contract may not have been instantiated and still refer to outer levels
11811 of template parameters. */
11814 /* For member functions, make this available for semantic analysis. */
11818 {
11822 }
11829 /* Rebuild the attribute. */
11831 }
11833 /* Rebuild the attribute list for DECL, substituting into contracts
11834 as needed. */
11836 void
11838 {
11841 {
11844 }
11846 }
11848 /* Instantiate a single dependent attribute T (a TREE_LIST), and return either
11849 T or a new TREE_LIST, possibly a chain in the case of a pack expansion. */
11851 static tree
11854 {
11857 /* Note that contract attributes are never substituted from this function.
11858 Their instantiation is triggered by regenerate_from_template_decl when
11859 we instantiate the body of the function. */
11867 {
11874 clauses
11878 else
11880 }
11884 {
11892 {
11897 {
11900 /* FIXME: The body of this loop should really be dispatching
11901 according to omp_ts_map[OMP_TS_CODE (TS)].tp_type instead
11902 of having hard-wired knowledge of specific selectors. */
11905 {
11913 }
11914 else
11915 {
11918 {
11923 {
11924 location_t loc
11926 match_loc);
11930 }
11932 {
11933 location_t loc
11935 match_loc);
11939 }
11941 }
11947 {
11948 bool allow_string
11958 {
11959 location_t loc
11961 match_loc);
11964 "integer expression or string "
11966 else
11970 }
11972 }
11973 }
11976 }
11978 }
11980 }
11981 /* If the first attribute argument is an identifier, don't
11982 pass it through tsubst. Attributes like mode, format,
11983 cleanup and several target specific attributes expect it
11984 unmodified. */
11986 {
11987 tree chain
11991 }
11993 {
11994 /* An attribute pack expansion. */
12003 {
12007 }
12009 }
12010 else
12018 }
12020 /* Instantiate any dependent attributes in ATTRIBUTES, returning either it
12021 unchanged or a new TREE_LIST chain. */
12023 static tree
12026 {
12031 {
12035 }
12039 {
12042 {
12045 {
12051 }
12052 }
12054 }
12057 }
12059 /* Apply any attributes which had to be deferred until instantiation
12060 time. DECL_P, ATTRIBUTES and ATTR_FLAGS are as cplus_decl_attributes;
12061 ARGS, COMPLAIN, IN_DECL are as tsubst. Returns true normally,
12062 false on error. */
12064 static bool
12067 {
12068 tree t;
12075 {
12079 /* DECL_ATTRIBUTES comes from copy_node in tsubst_decl, and is identical
12080 to our attributes parameter. */
12082 }
12083 else
12084 {
12086 /* TYPE_ATTRIBUTES was set up (with abi_tag and may_alias) in
12087 lookup_template_class_1, and should be preserved. */
12091 }
12093 /* save_template_attributes puts the dependent attributes at the beginning of
12094 the list; find the non-dependent ones. */
12100 /* Apply any non-dependent attributes. */
12106 /* And then any dependent ones. */
12110 {
12115 {
12118 }
12121 }
12123 /* cplus_decl_attributes can add some attributes implicitly. For templates,
12124 those attributes should have been added already when those templates were
12125 parsed, and shouldn't be added based on from which context they are
12126 first time instantiated. */
12129 optimization_default_node);
12132 NULL);
12138 }
12140 /* The template TMPL is being instantiated with the template arguments TARGS.
12141 Perform the access checks that we deferred when parsing the template. */
12143 static void
12145 {
12155 {
12163 /* Make access check error messages point to the location
12164 of the use of the typedef. */
12168 }
12169 }
12171 tree
12173 {
12177 tree typedecl;
12178 tree pbinfo;
12179 tree base_list;
12181 tree fn_context;
12191 /* Figure out which template is being instantiated. */
12195 /* Mark the type as in the process of being defined. */
12198 /* We may be in the middle of deferred access check. Disable
12199 it now. */
12202 /* Determine what specialization of the original template to
12203 instantiate. */
12208 {
12209 /* This TYPE is actually an instantiation of a partial
12210 specialization. We replace the innermost set of ARGS with
12211 the arguments appropriate for substitution. For example,
12212 given:
12214 template <class T> struct S {};
12215 template <class T> struct S<T*> {};
12217 and supposing that we are instantiating S<int*>, ARGS will
12218 presently be {int*} -- but we need {int}. */
12221 }
12222 else
12223 {
12226 }
12228 /* If the template we're instantiating is incomplete, then clearly
12229 there's nothing we can do. */
12231 {
12232 /* We can try again later. */
12235 }
12237 /* If we've recursively instantiated too many templates, stop. */
12245 /* Also avoid push_to_top_level for a lambda in an NSDMI. */
12250 else
12251 {
12254 }
12258 /* Use #pragma pack from the template context. */
12264 /* Set the input location to the most specialized template definition.
12265 This is needed if tsubsting causes an error. */
12279 {
12282 /* Adjust visibility for template arguments. */
12284 }
12290 /* We should never instantiate a nested class before its enclosing
12291 class; we need to look up the nested class by name before we can
12292 instantiate it, and that lookup should instantiate the enclosing
12293 class. */
12298 /* Defer access checking while we substitute into the types named in
12299 the base-clause. */
12302 {
12303 tree pbase_binfo;
12306 /* Substitute into each of the bases to determine the actual
12307 basetypes. */
12309 {
12310 tree base;
12316 {
12317 expanded_bases =
12324 }
12327 {
12329 /* Extract the already-expanded base class. */
12331 else
12332 /* Substitute to figure out the base class. */
12334 NULL_TREE);
12342 }
12343 }
12345 /* The list is now in reverse order; correct that. */
12347 }
12348 /* Now call xref_basetypes to set up all the base-class
12349 information. */
12357 /* Now that our base classes are set up, enter the scope of the
12358 class, so that name lookups into base classes, etc. will work
12359 correctly. This is precisely analogous to what we do in
12360 begin_class_definition when defining an ordinary non-template
12361 class, except we also need to push the enclosing classes. */
12364 /* Now check accessibility of the types named in its base-clause,
12365 relative to the scope of the class. */
12368 /* A vector to hold members marked with attribute used. */
12371 /* Now members are processed in the order of declaration. */
12374 {
12378 {
12380 {
12382 /* A closure type for a lambda in an NSDMI or default argument.
12383 Ignore it; it will be regenerated when needed. */
12386 /* If the member is a class template, we've
12387 already substituted its type. */
12397 {
12400 /* Now, install the tag. We don't use pushtag
12401 because that does too much work -- creating an
12402 implicit typedef, which we've already done. */
12407 }
12408 }
12410 {
12411 tree r;
12421 /* Instantiate members marked with attribute used. */
12427 }
12430 /* A closure type for a lambda in an NSDMI or default argument.
12432 else
12433 {
12434 /* Build new TYPE_FIELDS. */
12438 {
12439 tree r;
12444 /* The file and line for this declaration, to
12445 assist in error message reporting. Since we
12446 called push_tinst_level above, we don't need to
12447 restore these. */
12457 {
12458 /* A capture pack became multiple fields. */
12461 }
12464 {
12468 {
12469 /* In [temp.inst]:
12471 [t]he initialization (and any associated
12472 side-effects) of a static data member does
12473 not occur unless the static data member is
12474 itself used in a way that requires the
12475 definition of the static data member to
12476 exist.
12478 Therefore, we do not substitute into the
12479 initialized for the static data member here. */
12480 finish_static_data_member_decl
12486 /* Instantiate members marked with attribute used. */
12489 }
12491 {
12492 /* Determine whether R has a valid type and can be
12493 completed later. If R is invalid, then its type
12494 is replaced by error_mark_node. */
12500 {
12501 /* If R's type couldn't be completed and
12502 it isn't a flexible array member (whose
12503 type is incomplete by definition) give
12504 an error. */
12507 }
12512 {
12515 }
12519 }
12521 /* If it is a TYPE_DECL for a class-scoped
12522 ENUMERAL_TYPE, such a thing will already have
12523 been added to the field list by tsubst_enum
12524 in finish_member_declaration case above. */
12528 {
12531 }
12532 }
12533 }
12534 }
12535 }
12536 else
12537 {
12540 {
12541 /* Build new CLASSTYPE_FRIEND_CLASSES. */
12545 {
12546 /* template <class T> friend class C; */
12548 }
12550 {
12551 /* template <class T> friend class C::D; */
12556 }
12559 {
12560 /* This could be either
12562 friend class T::C;
12564 when dependent_type_p is false or
12566 template <class U> friend class T::C;
12568 otherwise. */
12569 /* Bump processing_template_decl in case this is something like
12570 template <class T> friend struct A<T>::B. */
12575 }
12577 /* friend class C<T>; */
12581 /* Otherwise it's
12583 friend class C;
12585 where C is already declared or
12587 friend class C<int>;
12589 We don't have to do anything in these cases. */
12593 }
12594 else
12595 {
12596 /* Build new DECL_FRIENDLIST. */
12597 tree r;
12599 /* The file and line for this declaration, to
12600 assist in error message reporting. Since we
12601 called push_tinst_level above, we don't need to
12602 restore these. */
12606 {
12609 }
12614 {
12617 }
12618 }
12619 }
12620 }
12623 {
12624 /* Restore these before substituting into the lambda capture
12625 initializers. */
12628 }
12630 /* Set the file and line number information to whatever is given for
12631 the class itself. This puts error messages involving generated
12632 implicit functions at a predictable point, and the same point
12633 that would be used for non-template classes. */
12640 /* Remember if instantiating this class ran into errors, so we can avoid
12641 instantiating member functions in limit_bad_template_recursion. We set
12642 this flag even if the problem was in another instantiation triggered by
12643 this one, as that will likely also cause trouble for member functions. */
12647 /* We don't instantiate default arguments for member functions. 14.7.1:
12649 The implicit instantiation of a class template specialization causes
12650 the implicit instantiation of the declarations, but not of the
12651 definitions or default arguments, of the class member functions,
12652 member classes, static data members and member templates.... */
12657 /* Now that we've gone through all the members, instantiate those
12658 marked with attribute used. We must do this in the context of
12659 the class -- not the context we pushed from, as that might be
12660 inside a template and change the behaviour of mark_used. */
12670 /* The vtable for a template class can be emitted in any translation
12671 unit in which the class is instantiated. When there is no key
12672 method, however, finish_struct_1 will already have added TYPE to
12673 the keyed_classes. */
12678 }
12680 tree
12682 {
12683 tree r;
12689 else
12690 {
12696 }
12699 }
12701 /* Given a function parameter pack TMPL_PARM and some function parameters
12702 instantiated from it at *SPEC_P, return a NONTYPE_ARGUMENT_PACK of them
12703 and set *SPEC_P to point at the next point in the list. */
12705 tree
12707 {
12708 /* Collect all of the extra "packed" parameters into an
12709 argument pack. */
12710 tree argpack;
12721 {
12722 /* The instantiation is still a parameter pack; don't wrap it in a
12723 NONTYPE_ARGUMENT_PACK. */
12726 }
12727 else
12728 {
12729 /* Fill in PARMVEC with all of the parameters. */
12733 {
12739 }
12741 /* Build the argument packs. */
12743 }
12747 }
12749 /* Give a chain SPEC_PARM of PARM_DECLs, pack them into a
12750 NONTYPE_ARGUMENT_PACK. */
12752 static tree
12754 {
12756 }
12758 /* Return 1 if the Ith element of the argument pack ARG_PACK is a
12759 pack expansion with no extra args, 2 if it has extra args, or 0
12760 if it is not a pack expansion. */
12762 static int
12764 {
12766 /* We're being called before this happens in tsubst_pack_expansion. */
12773 /* A decl pack is itself an expansion. */
12780 }
12783 /* Creates and return an ARGUMENT_PACK_SELECT tree node. */
12785 static tree
12787 {
12794 }
12796 /* This is a subroutine of tsubst_pack_expansion.
12798 It returns TRUE if we need to use the PACK_EXPANSION_EXTRA_ARGS
12799 mechanism to store the (non complete list of) arguments of the
12800 substitution and return a non substituted pack expansion, in order
12801 to wait for when we have enough arguments to really perform the
12802 substitution. */
12804 static bool
12806 tree parm_packs,
12809 {
12814 /* If one pack has an expansion and another pack has a normal
12815 argument or if one pack has an empty argument and an another
12816 one hasn't then tsubst_pack_expansion cannot perform the
12817 substitution and need to fall back on the
12818 PACK_EXPANSION_EXTRA mechanism. */
12822 {
12823 /* If all the actual packs are pack expansions, we can still
12824 subsitute directly. */
12826 {
12836 }
12838 }
12841 {
12845 parm_pack;
12847 {
12852 /* We can't substitute a pack expansion with extra args into
12853 our pattern. */
12857 else
12859 }
12862 {
12865 }
12866 }
12868 }
12870 /* [temp.variadic]/6 says that:
12872 The instantiation of a pack expansion [...]
12873 produces a list E1,E2, ..., En, where N is the number of elements
12874 in the pack expansion parameters.
12876 This subroutine of tsubst_pack_expansion produces one of these Ei.
12878 PATTERN is the pattern of the pack expansion. PARM_PACKS is a
12879 TREE_LIST in which each TREE_PURPOSE is a parameter pack of
12880 PATTERN, and each TREE_VALUE is its corresponding argument pack.
12881 INDEX is the index 'i' of the element Ei to produce. ARGS,
12882 COMPLAIN, and IN_DECL are the same parameters as for the
12883 tsubst_pack_expansion function.
12885 The function returns the resulting Ei upon successful completion,
12886 or error_mark_node.
12888 Note that this function possibly modifies the ARGS parameter, so
12889 it's the responsibility of the caller to restore it. */
12891 static tree
12893 tree parm_packs,
12895 tree args /* This parm gets
12897 tsubst_flags_t complain,
12898 tree in_decl)
12899 {
12900 tree t;
12903 /* For each parameter pack, change the substitution of the parameter
12904 pack to the ith argument in its argument pack, then expand the
12905 pattern. */
12907 {
12912 ith_elem_is_expansion |=
12915 /* Select the Ith argument from the pack. */
12919 {
12921 {
12926 }
12927 else
12929 }
12930 else
12931 {
12936 {
12938 /* Update the corresponding argument. */
12940 }
12941 else
12942 /* Re-use the ARGUMENT_PACK_SELECT. */
12944 }
12946 }
12948 /* Substitute into the PATTERN with the (possibly altered)
12949 arguments. */
12951 /* Expanding a fixed parameter pack from
12952 coerce_template_parameter_pack. */
12958 else
12959 {
12962 /* When expanding the fake auto... pack expansion from add_capture, we
12963 need to mark that the expansion is no longer a pack. */
12965 }
12967 /* If the Ith argument pack element is a pack expansion, then
12968 the Ith element resulting from the substituting is going to
12969 be a pack expansion as well. */
12974 }
12976 /* When the unexpanded parameter pack in a fold expression expands to an empty
12977 sequence, the value of the expression is as follows; the program is
12978 ill-formed if the operator is not listed in this table.
12980 && true
12981 || false
12982 , void() */
12984 tree
12986 {
12990 {
12999 }
13005 }
13007 /* Given a fold-expression T and a current LEFT and RIGHT operand,
13008 form an expression that combines the two terms using the
13009 operator of T. */
13011 static tree
13013 {
13018 // Handle compound assignment operators.
13025 {
13034 complain);
13035 }
13036 }
13038 /* Substitute ARGS into the pack of a fold expression T. */
13042 {
13044 }
13046 /* Substitute ARGS into the pack of a fold expression T. */
13050 {
13052 }
13054 /* Expand a PACK of arguments into a grouped as left fold.
13055 Given a pack containing elements A0, A1, ..., An and an
13056 operator @, this builds the expression:
13058 ((A0 @ A1) @ A2) ... @ An
13060 Note that PACK must not be empty.
13062 The operator is defined by the original fold expression T. */
13064 static tree
13066 {
13069 {
13072 }
13074 }
13076 /* Substitute into a unary left fold expression. */
13078 static tree
13080 tree in_decl)
13081 {
13086 {
13090 }
13093 else
13095 }
13097 /* Substitute into a binary left fold expression.
13099 Do ths by building a single (non-empty) vector of argumnts and
13100 building the expression from those elements. */
13102 static tree
13104 tree in_decl)
13105 {
13114 {
13119 }
13127 }
13129 /* Expand a PACK of arguments into a grouped as right fold.
13130 Given a pack containing elementns A0, A1, ..., and an
13131 operator @, this builds the expression:
13133 A0@ ... (An-2 @ (An-1 @ An))
13135 Note that PACK must not be empty.
13137 The operator is defined by the original fold expression T. */
13139 tree
13141 {
13142 // Build the expression.
13146 {
13149 }
13151 }
13153 /* Substitute into a unary right fold expression. */
13155 static tree
13157 tree in_decl)
13158 {
13163 {
13167 }
13170 else
13172 }
13174 /* Substitute into a binary right fold expression.
13176 Do ths by building a single (non-empty) vector of arguments and
13177 building the expression from those elements. */
13179 static tree
13181 tree in_decl)
13182 {
13191 {
13196 }
13205 }
13207 /* Walk through the pattern of a pack expansion, adding everything in
13208 local_specializations to a list. */
13210 class el_data
13211 {
13213 /* Set of variables declared within the pattern. */
13215 /* Set of AST nodes that have been visited by the traversal. */
13217 /* List of local_specializations used within the pattern. */
13218 tree extra;
13219 tsubst_flags_t complain;
13220 /* True iff we don't want to walk into unevaluated contexts. */
13222 /* The unevaluated contexts that we avoided walking. */
13227 };
13228 static tree
13230 {
13237 {
13241 }
13244 /* Remember local typedefs (85214). */
13248 {
13254 {
13257 decl2
13263 {
13266 }
13267 }
13268 }
13270 {
13271 /* Since we defer implicit capture, look in the parms and body. */
13277 }
13279 {
13281 /* Don't mess with variables declared within the pattern. */
13284 {
13285 /* Maybe pull out the PARM_DECL for a partial instantiation. */
13288 {
13294 }
13296 {
13297 /* Handle lambda capture here, since we aren't doing any
13298 substitution now, and so tsubst_copy won't call
13299 process_outer_var_ref. */
13303 {
13309 {
13310 /* Make a new NONTYPE_ARGUMENT_PACK of the capture
13311 proxies. */
13313 {
13318 }
13320 }
13321 }
13322 }
13323 }
13327 }
13329 }
13330 static tree
13332 {
13334 /* Walk the pattern twice, ignoring unevaluated operands the first time
13335 around, so that if a local specialization appears in both an evaluated
13336 and unevaluated context we prefer to process it in the evaluated context
13337 (since e.g. process_outer_var_ref is a no-op inside an unevaluated
13338 context). */
13341 /* Now walk the unevaluated contexts we skipped the first time around. */
13344 {
13347 }
13349 }
13351 /* Extract any uses of local_specializations from PATTERN and add them to ARGS
13352 for use in PACK_EXPANSION_EXTRA_ARGS. */
13354 tree
13356 {
13357 /* Make a copy of the extra arguments so that they won't get changed
13358 out from under us. */
13364 }
13366 /* Apply any local specializations from PACK_EXPANSION_EXTRA_ARGS and add the
13367 normal template args to ARGS. */
13369 tree
13371 {
13373 {
13375 {
13376 /* The partial instantiation involved local declarations collected in
13377 extract_local_specs; map from the general template to our local
13378 context. */
13384 /* else inst is already a full instantiation of the pack. */
13386 }
13389 }
13391 {
13392 /* This can happen after dependent substitution into a
13393 requires-expr or a lambda that uses constexpr if. */
13396 }
13397 else
13400 }
13402 /* Substitute ARGS into T, which is an pack expansion
13403 (i.e. TYPE_PACK_EXPANSION or EXPR_PACK_EXPANSION). Returns a
13404 TREE_VEC with the substituted arguments, a PACK_EXPANSION_* node
13405 (if only a partial substitution could be performed) or
13406 ERROR_MARK_NODE if there was an error. */
13407 tree
13409 tree in_decl)
13410 {
13411 tree pattern;
13415 tree result;
13422 /* Add in any args remembered from an earlier partial instantiation. */
13427 /* Determine the argument packs that will instantiate the parameter
13428 packs used in the expansion expression. While we're at it,
13429 compute the number of arguments to be expanded and make sure it
13430 is consistent. */
13433 {
13440 {
13445 else
13447 }
13449 {
13451 {
13454 parm_pack);
13456 }
13459 }
13461 {
13462 /* We know we have correct local_specializations if this
13463 expansion is at function scope, or if we're dealing with a
13464 local parameter in a requires expression; for the latter,
13465 tsubst_requires_expr set it up appropriately. */
13468 else
13469 /* We can't rely on local_specializations for a parameter
13470 name used later in a function declaration (such as in a
13471 late-specified return type). Even if it exists, it might
13472 have the wrong value for a recursive call. */
13476 {
13477 /* This parameter pack was used in an unevaluated context. Just
13478 make a dummy decl, since it's only used for its type. */
13483 /* Partial instantiation of the parm_pack, we can't build
13484 up an argument pack yet. */
13486 else
13488 }
13490 /* This argument pack isn't fully instantiated yet. */
13492 }
13494 {
13498 }
13499 else
13500 {
13509 }
13516 /* This can only happen if we forget to expand an argument
13517 pack somewhere else. Just return an error, silently. */
13518 {
13522 }
13525 {
13529 /* Don't bother trying to do a partial substitution with
13530 incomplete packs; we'll try again after deduction. */
13537 {
13542 pattern);
13543 else
13545 pattern);
13547 }
13549 /* Keep track of the parameter packs and their corresponding
13550 argument packs. */
13553 }
13554 else
13555 {
13556 /* We can't substitute for this parameter pack. We use a flag as
13557 well as the missing_level counter because function parameter
13558 packs don't have a level. */
13561 }
13562 }
13564 /* If the expansion is just T..., return the matching argument pack, unless
13565 we need to call convert_from_reference on all the elements. This is an
13566 important optimization; see c++/68422. */
13569 {
13572 /* If the argument pack is a single pack expansion, pull it out. */
13575 {
13579 /* Except if this isn't a simple sizeof...(T) which gets sZ
13581 else
13583 }
13585 /* Types need no adjustment, nor does sizeof..., and if we still have
13586 some pack expansion args we won't do anything yet. */
13591 /* Also optimize expression pack expansions if we can tell that the
13592 elements won't have reference type. */
13598 /* Otherwise use the normal path so we get convert_from_reference. */
13599 }
13601 /* We cannot expand this expansion expression, because we don't have
13602 all of the argument packs we need. */
13604 {
13605 /* We got some full packs, but we can't substitute them in until we
13606 have values for all the packs. So remember these until then. */
13612 }
13614 /* If NEED_LOCAL_SPECIALIZATIONS then we're in a late-specified return
13615 type, so create our own local specializations map; the current map is
13616 either NULL or (in the case of recursive unification) might have
13617 bindings that we don't want to use or alter. */
13622 {
13623 /* There were no real arguments, we're just replacing a parameter
13624 pack with another version of itself. Substitute into the
13625 pattern and return a PACK_EXPANSION_*. The caller will need to
13626 deal with that. */
13629 else
13635 {
13636 /* This is a fake auto... pack expansion created in add_capture with
13637 _PACKS that don't appear in the pattern. Copy one over. */
13644 }
13646 }
13650 /* For each argument in each argument pack, substitute into the
13651 pattern. */
13655 {
13657 i,
13659 in_decl);
13662 {
13665 }
13666 }
13668 /* Update ARGS to restore the substitution from parameter packs to
13669 their argument packs. */
13671 {
13678 else
13679 {
13687 /* Update the corresponding argument. */
13691 else
13693 }
13694 }
13696 /* If the dependent pack arguments were such that we end up with only a
13697 single pack expansion again, there's no need to keep it in a TREE_VEC. */
13703 }
13705 /* Make an argument pack out of the TREE_VEC VEC. */
13707 static tree
13709 {
13710 tree pack;
13714 else
13715 {
13718 }
13721 }
13723 /* Return an exact copy of template args T that can be modified
13724 independently. */
13726 static tree
13728 {
13736 {
13741 }
13747 }
13749 /* Substitute ARGS into the *_ARGUMENT_PACK orig_arg. */
13751 tree
13753 tree in_decl)
13754 {
13755 /* This flag is used only during deduction, and we don't expect to
13756 substitute such ARGUMENT_PACKs. */
13759 /* Substitute into each of the arguments. */
13768 /* If we're substituting into a generic ARGUMENT_PACK for a variadic
13769 template parameter, we might be able to avoid allocating a new
13770 ARGUMENT_PACK and reuse the corresponding ARGUMENT_PACK from ARGS
13771 if the substituted result is identical to it. */
13773 {
13780 {
13783 }
13784 }
13786 tree new_arg;
13788 {
13791 }
13792 else
13793 {
13796 }
13799 }
13801 /* Substitute ARGS into the vector or list of template arguments T. */
13803 tree
13805 {
13809 /* In "sizeof(X<I>)" we need to evaluate "I". */
13810 cp_evaluated ev;
13816 /* True iff the substituted result is identical to T. */
13820 {
13822 tree new_arg;
13829 {
13830 /* Substitute into an expansion expression. */
13834 /* Add to the expanded length adjustment the number of
13835 expanded arguments. We subtract one from this
13836 measurement, because the argument pack expression
13837 itself is already counted as 1 in
13838 LEN. EXPANDED_LEN_ADJUST can actually be negative, if
13839 the argument pack is empty. */
13841 }
13844 else
13853 }
13860 /* If ARGS and T are both multi-level, the substituted result may be
13861 identical to ARGS. */
13866 /* If T appears to be a vector of generic template arguments, the
13867 substituted result may be identical to the corresponding level
13868 from ARGS. */
13870 {
13875 }
13877 /* If the substituted result is identical to MAYBE_REUSE, return
13878 it and avoid allocating a new TREE_VEC, as an optimization. */
13884 /* If T consists of only a pack expansion for which substitution yielded
13885 a TREE_VEC of the expanded elements, then reuse that TREE_VEC instead
13886 of effectively making a copy. */
13892 /* Make space for the expanded arguments coming from template
13893 argument packs. */
13895 /* T can contain TREE_VECs. That happens if T contains the
13896 arguments for a member template.
13897 In that case each TREE_VEC in T represents a level of template
13898 arguments, and T won't carry any non defaulted argument count.
13899 It will rather be the nested TREE_VECs that will carry one.
13900 In other words, T carries a non defaulted argument count only
13901 if it doesn't contain any nested TREE_VEC. */
13903 {
13907 }
13911 {
13916 {
13917 /* Now expand the template argument pack "in place". */
13920 }
13921 else
13922 {
13924 out++;
13925 }
13926 }
13930 }
13932 /* Substitute ARGS into one level PARMS of template parameters. */
13934 static tree
13936 {
13943 {
13951 }
13954 }
13956 /* Return the result of substituting ARGS into the template parameters
13957 given by PARMS. If there are m levels of ARGS and m + n levels of
13958 PARMS, then the result will contain n levels of PARMS. For
13959 example, if PARMS is `template <class T> template <class U>
13960 template <T*, U, class V>' and ARGS is {{int}, {double}} then the
13961 result will be `template <int*, double, class V>'. */
13963 static tree
13965 {
13969 /* When substituting into a template, we must set
13970 PROCESSING_TEMPLATE_DECL as the template parameters may be
13971 dependent if they are based on one-another, and the dependency
13972 predicates are short-circuit outside of templates. */
13979 {
13988 }
13993 }
13995 /* Return the result of substituting ARGS into one template parameter
13996 given by T. T Must be a TREE_LIST which TREE_VALUE is the template
13997 parameter and which TREE_PURPOSE is the default argument of the
13998 template parameter. */
14000 static tree
14002 {
14025 }
14027 /* Substitute in-place the TEMPLATE_PARM_CONSTRAINTS of each template
14028 parameter in PARMS for sake of declaration matching. */
14030 static void
14032 tsubst_flags_t complain)
14033 {
14036 {
14042 }
14044 }
14046 /* Substitute the ARGS into the indicated aggregate (or enumeration)
14047 type T. If T is not an aggregate or enumeration type, it is
14048 handled as if by tsubst. IN_DECL is as for tsubst. If
14049 ENTERING_SCOPE is nonzero, T is the context for a template which
14050 we are presently tsubst'ing. Return the substituted value. */
14052 static tree
14054 tree args,
14055 tsubst_flags_t complain,
14056 tree in_decl,
14058 {
14062 /* Handle typedefs via tsubst so that they get consistently reused. */
14064 {
14069 /* The effect of entering_scope is that for a dependent specialization
14070 A<T>, lookup_template_class prefers to return A's primary template
14071 type instead of the implicit instantiation. So when entering_scope,
14072 we mirror this behavior by inspecting TYPE_CANONICAL appropriately,
14073 taking advantage of the fact that lookup_template_class links the two
14074 types by setting TYPE_CANONICAL of the latter to the former. */
14083 }
14086 {
14094 }
14095 }
14097 /* The part of tsubst_aggr_type that's shared with the RECORD_, UNION_
14098 and ENUMERAL_TYPE cases of tsubst. */
14100 static tree
14102 tree args,
14103 tsubst_flags_t complain,
14104 tree in_decl,
14106 {
14108 {
14111 /* Figure out what arguments are appropriate for the
14112 type we are trying to find. For example, given:
14114 template <class T> struct S;
14115 template <class T, class U> void f(T, U) { S<U> su; }
14117 and supposing that we are instantiating f<int, double>,
14118 then our ARGS will be {int, double}, but, when looking up
14119 S we only want {double}. */
14128 }
14129 else
14130 /* This is not a template type, so there's nothing to do. */
14132 }
14134 /* Map from a FUNCTION_DECL to a vec of default argument instantiations,
14135 indexed in reverse order of the parameters. */
14139 /* Return a reference to the vec* of defarg insts for FN. */
14143 {
14147 tree_vec_map **slot
14150 {
14153 }
14155 }
14157 /* Substitute into the default argument ARG (a default argument for
14158 FN), which has the indicated TYPE. */
14160 tree
14162 tsubst_flags_t complain)
14163 {
14166 /* This can happen in invalid code. */
14170 /* Shortcut {}. */
14185 /* Remember the location of the pointer to the vec rather than the location
14186 of the particular element, in case the vec grows in tsubst_expr. */
14188 /* Index in reverse order to avoid allocating space for initial parameters
14189 that don't have default arguments. */
14196 /* This default argument came from a template. Instantiate the
14197 default argument here, not in tsubst. In the case of
14198 something like:
14200 template <class T>
14201 struct S {
14202 static T t();
14203 void f(T = t());
14204 };
14206 we must be careful to do name lookup in the scope of S<T>,
14207 rather than in the current class. */
14211 /* So in_immediate_context knows this is a default argument. */
14215 /* The default argument expression may cause implicitly defined
14216 member functions to be synthesized, which will result in garbage
14217 collection. We must treat this situation as if we were within
14218 the body of function so as to avoid collecting live data on the
14219 stack. */
14226 /* Make sure the default argument is reasonable. */
14243 }
14245 /* Substitute into all the default arguments for FN. */
14247 static void
14249 {
14250 tree arg;
14251 tree tmpl_args;
14255 /* If this function is not yet instantiated, we certainly don't need
14256 its default arguments. */
14259 /* Don't do this again for clones. */
14265 arg;
14271 complain);
14272 }
14274 /* Hash table mapping a FUNCTION_DECL to its dependent explicit-specifier. */
14277 /* Store a pair to EXPLICIT_SPECIFIER_MAP. */
14279 void
14281 {
14286 }
14288 /* Lookup an element in EXPLICIT_SPECIFIER_MAP. */
14290 tree
14292 {
14294 }
14296 /* Given T, a FUNCTION_TYPE or METHOD_TYPE, construct and return a corresponding
14297 FUNCTION_TYPE or METHOD_TYPE whose return type is RETURN_TYPE, argument types
14298 are ARG_TYPES, and exception specification is RAISES, and otherwise is
14299 identical to T. */
14301 static tree
14304 {
14307 tree new_type;
14309 {
14312 }
14313 else
14314 {
14316 /* Don't pick up extra function qualifiers from the basetype. */
14319 {
14320 /* [temp.deduct]
14322 Type deduction may fail for any of the following
14323 reasons:
14325 -- Attempting to create "pointer to member of T" when T
14326 is not a class type. */
14329 r);
14331 }
14335 }
14341 }
14343 /* Check if the function type of DECL, a FUNCTION_DECL, agrees with the type of
14344 each of its formal parameters. If there is a disagreement then rebuild
14345 DECL's function type according to its formal parameter types, as part of a
14346 resolution for Core issues 1001/1322. */
14348 static void
14350 {
14353 {
14356 {
14360 {
14363 }
14367 }
14368 }
14379 {
14384 }
14386 {
14396 }
14404 }
14406 /* Subroutine of tsubst_decl for the case when T is a FUNCTION_DECL. */
14408 static tree
14411 {
14416 /* Nobody should be tsubst'ing into non-template functions. */
14421 {
14424 }
14426 {
14427 /* If T is not dependent, just return it. */
14432 /* A non-templated friend doesn't get DECL_TEMPLATE_INFO. */
14436 /* Calculate the most general template of which R is a
14437 specialization. */
14440 /* We're substituting a lambda function under tsubst_lambda_expr but not
14441 directly from it; find the matching function we're already inside.
14442 But don't do this if T is a generic lambda with a single level of
14443 template parms, as in that case we're doing a normal instantiation. */
14449 /* Calculate the complete set of arguments used to
14450 specialize R. */
14452 {
14454 (DECL_TEMPLATE_RESULT
14460 /* Check to see if we already have this specialization. */
14463 /* The spec for these args might be a partial instantiation of the
14464 template, but here what we want is the FUNCTION_DECL. */
14466 }
14467 else
14469 }
14470 else
14471 {
14472 /* This special case arises when we have something like this:
14474 template <class T> struct S {
14475 friend void f<int>(int, double);
14476 };
14478 Here, the DECL_TI_TEMPLATE for the friend declaration
14479 will be an IDENTIFIER_NODE. We are being called from
14480 tsubst_friend_function, and we want only to create a
14481 new decl (R) with appropriate types so that we can call
14482 determine_specialization. */
14483 friend_case:
14486 }
14493 /* If this is a static or xobj lambda, remove the 'this' pointer added in
14494 tsubst_lambda_expr now that we know the closure type. */
14508 /* If we hit excessive deduction depth, the type is bogus even if
14509 it isn't error_mark_node, so don't build a decl. */
14513 /* We do NOT check for matching decls pushed separately at this
14514 point, as they may not represent instantiations of this
14515 template, and in any case are considered separate under the
14516 discrete model. */
14520 /* Clear out the mangled name and RTL for the instantiation. */
14523 /* Leave DECL_INITIAL set on deleted instantiations. */
14529 /* Handle explicit(dependent-expr). */
14531 {
14539 else
14540 {
14543 }
14544 }
14546 /* OpenMP UDRs have the only argument a reference to the declared
14547 type. We want to diagnose if the declared type is a reference,
14548 which is invalid, but as references to references are usually
14549 quietly merged, diagnose it here. */
14551 {
14552 tree argtype
14557 "reference type %qT in "
14561 argtype);
14562 }
14565 /* Type-conversion operator. Reconstruct the name, in
14566 case it's the name of one of the template's parameters. */
14576 {
14581 }
14590 /* If this is an instantiation of a function with internal
14591 linkage, we already know what object file linkage will be
14592 assigned to the instantiation. */
14601 /* We'll re-clone as appropriate in instantiate_template. */
14604 /* If we aren't complaining now, return on error before we register
14605 the specialization so that we'll complain eventually. */
14611 /* If we are looking at an xobj lambda, we might need to check the type of
14612 its xobj parameter. */
14614 {
14621 /* If a lambda has an empty capture clause, an xobj parameter of
14624 /* If we are coming from tsubst_lambda_expr we might not have
14625 substituted into our xobj parameter yet. We can't error out until
14626 we know what the type really is so do nothing...
14627 ...but if we are instantiating the call op for real and we don't
14628 have a real type then something has gone incredibly wrong. */
14630 else
14631 {
14632 /* We have a lambda with captures, and know the type of the xobj
14633 parameter, time to check it. */
14636 {
14637 /* This error does not emit when the lambda's call operator
14638 template is instantiated by taking its address, such as in
14639 the following case:
14641 auto f = [x = 0](this auto&&){};
14642 int (*fp)(int&) = &decltype(f)::operator();
14644 It only emits when explicitly calling the call operator with
14645 an explicit template parameter:
14647 template<typename T>
14648 struct S : T {
14649 using T::operator();
14650 operator int() const {return {};}
14651 };
14653 auto s = S{[x = 0](this auto&&) {}};
14654 s.operator()<int>();
14656 This is due to resolve_address_of_overloaded_function being
14657 deficient at reporting candidates when overload resolution
14658 fails.
14660 This diagnostic will be active in the first case if/when
14661 resolve_address_of_overloaded_function is fixed to properly
14662 emit candidates upon failure to resolve to an overload. */
14667 }
14668 }
14669 }
14671 /* Associate the constraints directly with the instantiation. We
14672 don't substitute through the constraints; that's only done when
14673 they are checked. */
14686 /* Set up the DECL_TEMPLATE_INFO for R. There's no need to do
14687 this in the special friend case mentioned above where
14688 GEN_TMPL is NULL. */
14690 {
14696 {
14697 tree new_r
14700 /* We instantiated this while substituting into
14701 the type earlier (template/friend54.C). */
14703 }
14705 /* We're not supposed to instantiate default arguments
14706 until they are called, for a template. But, for a
14707 declaration like:
14709 template <class T> void f ()
14710 { extern void g(int i = T()); }
14712 we should do the substitution when the template is
14713 instantiated. We handle the member function case in
14714 instantiate_class_template since the default arguments
14715 might refer to other members of the class. */
14720 }
14722 {
14725 }
14726 else
14729 /* Copy the list of befriending classes. */
14733 {
14737 }
14740 {
14744 /* If this is an instantiation of a member template, clone it.
14745 If it isn't, that'll be handled by
14746 clone_constructors_and_destructors. */
14749 }
14755 /* Possibly limit visibility based on template args. */
14758 {
14762 }
14776 }
14778 /* Subroutine of tsubst_decl for the case when T is a TEMPLATE_DECL. */
14780 static tree
14783 {
14784 /* We can get here when processing a member function template,
14785 member class template, or template template parameter. */
14788 tree spec;
14789 tree tmpl_args;
14791 tree r;
14795 {
14796 /* Template template parameter is treated here. */
14800 /* If we get a real template back, return it. This can happen in
14801 the context of most_specialized_partial_spec. */
14804 else
14805 /* The new TEMPLATE_DECL was built in
14806 reduce_template_parm_level. */
14809 }
14812 {
14813 /* We might already have an instance of this template.
14814 The ARGS are for the surrounding class type, so the
14815 full args contain the tsubst'd args for the context,
14816 plus the innermost args from the template decl. */
14820 /* Because this is a template, the arguments will still be
14821 dependent, even after substitution. If
14822 PROCESSING_TEMPLATE_DECL is not set, the dependency
14823 predicates will short-circuit. */
14831 /* If this is a default template template argument,
14832 tsubst might not have changed anything. */
14839 {
14841 /* Type partial instantiations are stored as the type by
14842 lookup_template_class_1, not here as the template. */
14847 }
14848 }
14850 /* Make a new template decl. It will be similar to the
14851 original, but will record the current template arguments.
14852 We also create a new function declaration, which is just
14853 like the old one, but points to this new template, rather
14854 than the old one. */
14859 // Build new template info linking to the original template decl.
14861 {
14864 }
14865 else
14868 /* The template parameters for this new template are all the
14869 template parameters for the old template, except the
14870 outermost level of parameters. */
14873 = current_template_parms
14874 = (lambda_tparms
14875 ? lambda_tparms
14877 complain));
14885 else
14886 {
14888 {
14891 }
14895 else
14897 }
14903 {
14904 /* For a partial specialization, we need to keep pointing to
14905 the primary template. */
14907 {
14910 }
14914 }
14916 {
14919 }
14920 else
14921 {
14923 /* Set DECL_TI_ARGS to the full set of template arguments,
14924 which tsubst_function_decl / tsubst_decl didn't do due to
14925 use_spec_table=false. */
14928 }
14935 {
14936 /* Propagate module information from the decl. */
14939 /* If this is a constrained template, the above tsubst of
14940 inner can find the unconstrained template, which may have
14941 come from an import. This is ok, because we don't
14942 register this instantiation (see below). */
14944 || (TEMPLATE_PARMS_CONSTRAINTS
14946 }
14957 {
14958 /* Record this non-type partial instantiation. */
14959 /* FIXME we'd like to always register the TEMPLATE_DECL, or always
14960 the DECL_TEMPLATE_RESULT, but it seems the modules code relies
14961 on this current behavior. */
14964 else
14966 }
14969 }
14971 /* True if FN is the op() for a lambda in an uninstantiated template. */
14973 bool
14975 {
14980 }
14982 /* True if FN is the substitution (via tsubst_lambda_expr) of a function for
14983 which the above is true. */
14985 bool
14987 {
14993 }
14995 /* Return the LAMBDA_EXPR from which T was ultimately regenerated.
14996 If T is not a regenerated LAMBDA_EXPR, return T. */
14998 tree
15000 {
15004 }
15006 /* Return the set of template arguments used to regenerate the lambda T
15007 from its most general lambda. */
15009 tree
15011 {
15017 else
15019 }
15021 /* We're instantiating a variable from template function TCTX. Return the
15022 corresponding current enclosing scope. We can match them up using
15023 DECL_SOURCE_LOCATION because lambdas only ever have one source location, and
15024 the DECL_SOURCE_LOCATION for a function instantiation is updated to match
15025 the template definition in regenerate_decl_from_template. */
15027 static tree
15029 {
15032 /* We shouldn't ever need to do this for other artificial functions. */
15039 }
15041 /* Substitute the ARGS into the T, which is a _DECL. Return the
15042 result of the substitution. Issue error and warning messages under
15043 control of COMPLAIN. The flag USE_SPEC_TABLE controls if we look up
15044 and insert into the specializations table or if we can assume it's
15045 the caller's responsibility; this is used by instantiate_template
15046 to avoid doing some redundant work. */
15048 static tree
15051 {
15052 #define RETURN(EXP) do { r = (EXP); goto out; } while(0)
15053 location_t saved_loc;
15061 /* Set the filename and linenumber to improve error-reporting. */
15066 {
15075 use_spec_table);
15079 {
15087 {
15088 /* If there is a local specialization that isn't a
15089 parameter pack, it means that we're doing a "simple"
15090 substitution from inside tsubst_pack_expansion. Just
15091 return the local specialization (which will be a single
15092 parm). */
15099 /* Expand the TYPE_PACK_EXPANSION that provides the types for
15100 the parameters in this function parameter pack. */
15104 {
15107 /* Zero-length parameter packs are boring. Just substitute
15108 into the chain. */
15112 }
15113 else
15114 {
15115 /* All we did was update the type. Make a note of that. */
15118 }
15119 }
15121 /* Loop through all of the parameters we'll build. When T is
15122 a function parameter pack, LEN is the number of expanded
15123 types in EXPANDED_TYPES; otherwise, LEN is 1. */
15126 {
15133 /* We're on the Ith parameter of the function parameter
15134 pack. */
15135 {
15136 /* Get the Ith type. */
15139 /* Rename the parameter to include the index. */
15142 }
15144 /* We're dealing with a normal parameter. */
15152 {
15155 else
15158 }
15169 /* Keep track of the first new parameter we
15170 generate. That's what will be returned to the
15171 caller. */
15175 /* Build a proper chain of parameters when substituting
15176 into a function parameter pack. */
15179 }
15181 /* If cp_unevaluated_operand is set, we're just looking for a
15182 single dummy parameter, so don't keep going. */
15187 /* FIRST_R contains the start of the chain we've built. */
15189 }
15193 {
15200 {
15201 /* This field is a lambda capture pack. Return a TREE_VEC of
15202 the expanded fields to instantiate_class_template_1. */
15206 {
15209 }
15210 else
15211 {
15212 /* All we did was update the type. Make a note of that. */
15215 }
15216 }
15219 {
15222 {
15226 }
15236 /* For bit-fields, DECL_BIT_FIELD_REPRESENTATIVE gives the
15237 number of bits. */
15242 {
15243 /* Set up DECL_TEMPLATE_INFO so that we can get at the
15244 NSDMI in perform_member_init. Still set DECL_INITIAL
15245 so that we know there is one. */
15250 }
15251 /* We don't have to set DECL_CONTEXT here; it is set by
15252 finish_member_declaration. */
15261 }
15265 }
15269 /* We reach here only for member using decls. We also need to check
15270 uses_template_parms because DECL_DEPENDENT_P is not set for a
15271 using-declaration that designates a member of the current
15272 instantiation (c++/53549). */
15275 {
15276 /* True iff this using-decl was written as a pack expansion
15277 (and a pack appeared in its scope or name). If a pack
15278 appeared in both, we expand the packs separately and
15279 manually merge them. */
15284 {
15287 in_decl);
15289 }
15290 else
15296 {
15300 {
15303 }
15307 }
15308 else
15316 {
15318 {
15323 }
15325 }
15333 {
15342 {
15345 }
15349 }
15353 }
15354 else
15355 {
15358 }
15363 {
15374 {
15375 /* If this is the canonical decl, we don't have to
15376 mess with instantiations, and often we can't (for
15377 typename, template type parms and such). Note that
15378 TYPE_NAME is not correct for the above test if
15379 we've copied the type for a typedef. */
15385 }
15387 /* Check to see if we already have the specialization we
15388 need. */
15394 {
15397 {
15399 complain,
15402 /* The context and type of an injected-class-name are
15403 the same, so we don't need to substitute both. */
15405 /* If CTX is unchanged, then T is in fact the
15406 specialization we want. That situation occurs when
15407 referencing a static data member within in its own
15408 class. We can use pointer equality, rather than
15409 same_type_p, because DECL_CONTEXT is always
15410 canonical... */
15412 /* ... unless T is a member template; in which
15413 case our caller can be willing to create a
15414 specialization of that template represented
15415 by T. */
15419 }
15422 {
15425 {
15432 }
15433 else
15435 }
15436 }
15437 else
15438 {
15440 /* Subsequent calls to pushdecl will fill this in. */
15442 /* A local variable. */
15444 /* Unless this is a reference to a static variable from an
15445 enclosing function, in which case we need to fill it in now. */
15447 {
15451 }
15453 }
15454 /* If we already have the specialization we need, there is
15455 nothing more to do. */
15457 {
15460 }
15462 /* Create a new node for the specialization we need. */
15464 {
15467 else
15477 /* Substituting the type might have recursively instantiated this
15478 same alias (c++/86171). */
15481 {
15484 }
15485 }
15490 {
15494 {
15495 /* It may seem that this case cannot occur, since:
15497 typedef void f();
15498 void g() { f x; }
15500 declares a function, not a variable. However:
15502 typedef void f();
15503 template <typename T> void g() { T t; }
15504 template void g<f>();
15506 is an attempt to declare a variable with function
15507 type. */
15509 /* R is not yet sufficiently initialized, so we
15510 just use its name. */
15513 }
15515 /* Wait until cp_finish_decl to set this again, to handle
15516 circular dependency (template/instantiate6.C). */
15521 {
15523 /* If the DECL_VALUE_EXPR is converted to the declared type,
15524 preserve the identity so that gimplify_type_sizes works. */
15530 {
15533 }
15542 else
15546 }
15550 }
15556 /* Clear out the mangled name and RTL for the instantiation. */
15562 /* The initializer must not be expanded until it is required;
15563 see [temp.inst]. */
15567 {
15573 /* Possibly limit visibility based on template args. */
15576 {
15580 }
15584 }
15587 {
15588 /* A static data member declaration is always marked
15589 external when it is declared in-class, even if an
15590 initializer is present. We mimic the non-template
15591 processing here. */
15600 }
15601 else
15602 {
15607 }
15616 /* Preserve a typedef that names a type. */
15618 {
15622 /* common_handle_aligned_attribute doesn't apply the alignment
15623 to DECL_ORIGINAL_TYPE. */
15627 }
15630 }
15635 }
15636 #undef RETURN
15638 out:
15639 /* Restore the file and line information. */
15643 }
15645 /* Substitute into the complete parameter type list PARMS. */
15647 tree
15649 tree args,
15650 tsubst_flags_t complain,
15651 tree in_decl)
15652 {
15654 }
15656 /* Substitute into the ARG_TYPES of a function type.
15657 If END is a TREE_CHAIN, leave it and any following types
15658 un-substituted. */
15660 static tree
15662 tree args,
15663 tree end,
15664 tsubst_flags_t complain,
15665 tree in_decl)
15666 {
15675 {
15676 /* For a pack expansion, perform substitution on the
15677 entire expression. Later on, we'll handle the arguments
15678 one-by-one. */
15683 /* So that we'll spin through the parameters, one by one. */
15685 else
15686 {
15687 /* We only partially substituted into the parameter
15688 pack. Our type is TYPE_PACK_EXPANSION. */
15691 }
15692 }
15693 else
15696 /* Check if a substituted type is erroneous before substituting into
15697 the rest of the chain. */
15699 {
15706 {
15708 {
15712 }
15714 }
15715 }
15717 /* We do not substitute into default arguments here. The standard
15718 mandates that they be instantiated only when needed, which is
15719 done in build_over_call. */
15722 /* Except that we do substitute default arguments under tsubst_lambda_expr,
15723 since the new op() won't have any associated template arguments for us
15724 to refer to later. */
15736 {
15740 /* Do array-to-pointer, function-to-pointer conversion, and ignore
15741 top-level qualifiers as required. */
15745 {
15746 /* We've instantiated a template before its default arguments
15747 have been parsed. This can happen for a nested template
15748 class, and is not an error unless we require the default
15749 argument in a call of this function. */
15750 remaining_arg_types
15753 remaining_arg_types);
15754 }
15755 else
15756 remaining_arg_types
15758 }
15761 }
15763 /* Substitute into a FUNCTION_TYPE or METHOD_TYPE. This routine does
15764 *not* handle the exception-specification for FNTYPE, because the
15765 initial substitution of explicitly provided template parameters
15766 during argument deduction forbids substitution into the
15767 exception-specification:
15769 [temp.deduct]
15771 All references in the function type of the function template to the
15772 corresponding template parameters are replaced by the specified tem-
15773 plate argument values. If a substitution in a template parameter or
15774 in the function type of the function template results in an invalid
15775 type, type deduction fails. [Note: The equivalent substitution in
15776 exception specifications is done only when the function is instanti-
15777 ated, at which point a program is ill-formed if the substitution
15778 results in an invalid type.] */
15780 static tree
15782 tree args,
15783 tsubst_flags_t complain,
15784 tree in_decl)
15785 {
15786 tree return_type;
15789 /* The TYPE_CONTEXT is not used for function/method types. */
15792 /* DR 1227: Mixing immediate and non-immediate contexts in deduction
15793 failure. */
15797 {
15798 /* Substitute the argument types. */
15810 {
15811 /* DR 1207: 'this' is in scope in the trailing return type. */
15813 }
15815 /* Substitute the return type. */
15819 {
15822 }
15823 }
15824 else
15825 /* Substitute the return type. */
15830 /* DR 486 clarifies that creation of a function type with an
15831 invalid return type is a deduction failure. */
15834 {
15836 {
15839 else
15841 }
15843 }
15846 {
15847 /* Substitute the argument types. */
15852 }
15854 /* Construct a new type node and return it. */
15857 }
15859 /* FNTYPE is a FUNCTION_TYPE or METHOD_TYPE. Substitute the template
15860 ARGS into that specification, and return the substituted
15861 specification. If there is no specification, return NULL_TREE. */
15863 static tree
15865 tree args,
15866 tsubst_flags_t complain,
15867 tree in_decl,
15869 {
15870 tree specs;
15871 tree new_specs;
15876 {
15877 /* A noexcept-specifier. */
15882 {
15883 /* Defer instantiation of noexcept-specifiers to avoid
15884 excessive instantiations (c++/49107). */
15887 {
15888 /* We already partially instantiated this member template,
15889 so combine the new args with the old. */
15894 }
15895 else
15896 {
15899 }
15900 }
15901 else
15902 {
15904 {
15906 args);
15908 }
15910 }
15912 /* We've instantiated a template before a noexcept-specifier
15913 contained therein has been parsed. This can happen for
15914 a nested template class:
15916 struct S {
15917 template<typename> struct B { B() noexcept(...); };
15918 struct A : B<int> { ... use B() ... };
15919 };
15921 where completing B<int> will trigger instantiating the
15922 noexcept, even though we only parse it at the end of S. */
15924 {
15927 }
15928 }
15930 {
15933 else
15935 {
15936 tree spec;
15941 {
15942 /* Expand the pack expansion type. */
15945 in_decl);
15951 else
15952 {
15953 /* We're substituting into a member template, so
15954 we got a TYPE_PACK_EXPANSION back. Add that
15955 expansion and move on. */
15959 expanded_specs,
15960 complain);
15963 }
15964 }
15967 {
15970 else
15975 complain);
15976 }
15979 }
15980 }
15982 }
15984 /* Substitute through a TREE_LIST of types or expressions, handling pack
15985 expansions. */
15987 tree
15989 {
15996 ;
15998 {
16002 }
16005 else
16013 ;
16015 {
16019 }
16022 else
16029 ;
16034 else
16045 /* Determine the number of arguments. */
16047 {
16050 }
16053 else
16057 {
16065 else
16067 }
16070 }
16072 /* Take the tree structure T and replace template parameters used
16073 therein with the argument vector ARGS. IN_DECL is an associated
16074 decl for diagnostics. If an error occurs, returns ERROR_MARK_NODE.
16075 Issue error and warning messages under control of COMPLAIN. Note
16076 that we must be relatively non-tolerant of extensions here, in
16077 order to preserve conformance; if we allow substitutions that
16078 should not be allowed, we may allow argument deductions that should
16079 not succeed, and therefore report ambiguous overload situations
16080 where there are none. In theory, we could allow the substitution,
16081 but indicate that it should have failed, and allow our caller to
16082 make sure that the right thing happens, but we don't try to do this
16083 yet.
16085 This function is used for dealing with types, decls and the like;
16086 for expressions, use tsubst_expr or tsubst_copy. */
16088 tree
16090 {
16125 /* Reuse typedefs. We need to do this to handle dependent attributes,
16126 such as attribute aligned. */
16129 {
16133 {
16134 /* DECL represents an alias template and we want to
16135 instantiate it. */
16139 }
16143 {
16147 }
16152 else
16153 /* The typedef is from a non-template context. */
16157 {
16159 r = cp_build_qualified_type
16163 }
16164 else
16165 {
16166 /* We don't have an instantiation yet, so drop the typedef. */
16171 }
16172 }
16189 {
16193 /* Fall through. */
16219 {
16224 /* Fix up type of the magic NOP_EXPR with TREE_SIDE_EFFECTS if
16225 needed. */
16231 /* If we're in a partial instantiation, preserve the magic NOP_EXPR
16232 with TREE_SIDE_EFFECTS that indicates this is not an integral
16233 constant expression. */
16236 {
16239 }
16242 }
16246 {
16254 else
16256 }
16257 /* Fall through. */
16261 {
16275 {
16278 /* See through ARGUMENT_PACK_SELECT arguments. */
16281 }
16286 {
16288 /* If ARG is an argument pack, we don't actually want to
16289 perform a substitution here, because substitutions
16290 for argument packs are only done
16291 element-by-element. We can get to this point when
16292 substituting the type of a non-type template
16293 parameter pack, when that type actually contains
16294 template parameter packs from an outer template, e.g.,
16296 template<typename... Types> struct A {
16297 template<Types... Values> struct B { };
16298 }; */
16302 {
16305 /* When building concept checks for the purpose of
16306 deducing placeholders, we can end up with wildcards
16307 where types are expected. Adjust this to the deduced
16308 value. */
16316 return cp_build_qualified_type
16318 }
16320 {
16321 /* We are processing a type constructed from a
16322 template template parameter. */
16333 /* Consider this code:
16335 template <template <class> class Template>
16336 struct Internal {
16337 template <class Arg> using Bind = Template<Arg>;
16338 };
16340 template <template <class> class Template, class Arg>
16341 using Instantiate = Template<Arg>; //#0
16343 template <template <class> class Template,
16344 class Argument>
16345 using Bind =
16346 Instantiate<Internal<Template>::template Bind,
16347 Argument>; //#1
16349 When #1 is parsed, the
16350 BOUND_TEMPLATE_TEMPLATE_PARM representing the
16351 parameter `Template' in #0 matches the
16352 UNBOUND_CLASS_TEMPLATE representing the argument
16353 `Internal<Template>::template Bind'; We then want
16354 to assemble the type `Bind<Argument>' that can't
16355 be fully created right now, because
16356 `Internal<Template>' not being complete, the Bind
16357 template cannot be looked up in that context. So
16358 we need to "store" `Bind<Argument>' for later
16359 when the context of Bind becomes complete. Let's
16360 store that in a TYPENAME_TYPE. */
16364 argvec),
16365 typename_type,
16366 complain);
16368 /* We can get a TEMPLATE_TEMPLATE_PARM here when we
16369 are resolving nested-types in the signature of a
16370 member function templates. Otherwise ARG is a
16371 TEMPLATE_DECL and is the real template to be
16372 instantiated. */
16380 complain);
16381 return cp_build_qualified_type
16383 }
16386 else
16387 /* TEMPLATE_PARM_INDEX. */
16389 }
16392 /* This can happen during the attempted tsubst'ing in
16393 unify. This means that we don't yet have any information
16394 about the template parameter in question. */
16397 /* Early in template argument deduction substitution, we don't
16398 want to reduce the level of 'auto', or it will be confused
16399 with a normal template parm in subsequent deduction.
16400 Similarly, don't reduce the level of template parameters to
16401 avoid mismatches when deducing their types. */
16405 /* If we get here, we must have been looking at a parm for a
16406 more deeply nested template. Make a new version of this
16407 template parameter, but with a lower level. */
16410 {
16415 {
16418 }
16424 /* Cache lowering a type parameter or a simple template
16425 template parameter. */
16429 {
16441 /* Propagate constraints on placeholders since they are
16442 only instantiated during satisfaction. */
16447 else
16449 }
16457 {
16459 /* We might need to substitute into the types of non-type
16460 template parameters. This also lowers the level of
16461 the ttp appropriately. */
16474 }
16477 /* OK, now substitute the type of the non-type parameter. We
16478 couldn't do it earlier because it might be an auto parameter,
16479 and we wouldn't need to if we had an argument. */
16488 }
16491 }
16497 /* We should never be tsubsting a binfo. */
16501 /* A vector of template arguments. */
16507 {
16511 /* [temp.deduct]
16513 Type deduction may fail for any of the following
16514 reasons:
16516 -- Attempting to create a pointer to reference type.
16517 -- Attempting to create a reference to a reference type or
16518 a reference to void.
16520 Core issue 106 says that creating a reference to a reference
16521 during instantiation is no longer a cause for failure. We
16522 only enforce this check in strict C++98 mode. */
16526 {
16529 /* We keep track of the last time we issued this error
16530 message to avoid spewing a ton of messages during a
16531 single bad template instantiation. */
16534 {
16539 else
16542 }
16545 }
16549 {
16551 {
16554 type);
16555 else
16557 type);
16558 }
16560 }
16562 {
16566 }
16568 /* In C++0x, during template argument substitution, when there is an
16569 attempt to create a reference to a reference type, reference
16570 collapsing is applied as described in [14.3.1/4 temp.arg.type]:
16572 "If a template-argument for a template-parameter T names a type
16573 that is a reference to a type A, an attempt to create the type
16574 'lvalue reference to cv T' creates the type 'lvalue reference to
16575 A,' while an attempt to create the type type rvalue reference to
16576 cv T' creates the type T"
16577 */
16578 r = cp_build_reference_type
16581 else
16586 /* Will this ever be needed for TYPE_..._TO values? */
16590 }
16592 {
16595 {
16596 /* [temp.deduct]
16598 Type deduction may fail for any of the following
16599 reasons:
16601 -- Attempting to create "pointer to member of T" when T
16602 is not a class type. */
16606 }
16608 {
16612 }
16614 {
16618 }
16621 {
16622 /* The type of the implicit object parameter gets its
16623 cv-qualifiers from the FUNCTION_TYPE. */
16624 tree memptr;
16625 tree method_type
16630 complain);
16631 }
16632 else
16635 complain);
16636 }
16639 {
16640 tree fntype;
16641 tree specs;
16646 /* Substitute the exception specification. */
16654 }
16656 {
16661 /* As an optimization, we avoid regenerating the array type if
16662 it will obviously be the same as T. */
16666 /* These checks should match the ones in create_array_type_for_decl.
16668 [temp.deduct]
16670 The deduction may fail for any of the following reasons:
16672 -- Attempting to create an array with an element type that
16673 is void, a function type, or a reference type, or [DR337]
16674 an abstract class type. */
16680 {
16684 }
16697 {
16700 }
16703 }
16706 {
16709 {
16712 in_decl);
16717 {
16722 }
16724 }
16725 else
16738 {
16742 }
16744 {
16745 /* Normally, make_typename_type does not require that the CTX
16746 have complete type in order to allow things like:
16748 template <class T> struct S { typename S<T>::X Y; };
16750 But, such constructs have already been resolved by this
16751 point, so here CTX really should have complete type, unless
16752 it's a partial instantiation. */
16755 }
16757 /* FIXME: TYPENAME_IS_CLASS_P conflates 'class' vs 'struct' vs 'union'
16758 tags. TYPENAME_TYPE should probably remember the exact tag that
16759 was written. */
16760 enum tag_types tag_type
16770 {
16773 }
16776 {
16778 {
16782 else
16784 }
16786 {
16790 else
16792 }
16793 }
16795 return cp_build_qualified_type
16797 }
16800 {
16812 }
16815 {
16816 tree type;
16830 complain);
16831 }
16834 {
16835 tree type;
16852 else
16853 {
16857 /* In a template ~id could be either a complement expression
16858 or an unqualified-id naming a destructor; if instantiating
16859 it produces an expression, it's not an id-expression or
16860 member access. */
16863 }
16868 }
16871 {
16875 else
16882 }
16902 /* We should use one of the expression tsubsts for these codes. */
16908 }
16909 }
16911 /* Convenience wrapper over tsubst for substituting into the LHS
16912 of the :: scope resolution operator. */
16914 static tree
16916 {
16919 }
16921 /* Convenience wrapper over tsubst for substituting into an id-expression
16922 without resolving its terminal name. */
16924 static tree
16926 {
16928 }
16930 /* OLDFNS is a lookup set of member functions from some class template, and
16931 NEWFNS is a lookup set of member functions from NEWTYPE, a specialization
16932 of that class template. Return the subset of NEWFNS which are
16933 specializations of a function from OLDFNS. */
16935 static tree
16937 {
16938 /* Record all member functions from the old lookup set OLDFNS into
16939 VISIBLE_SET. */
16943 {
16945 {
16946 /* Imprecisely handle dependent using-decl by keeping all members
16947 in the new lookup set that are defined in a base class, i.e.
16948 members that could plausibly have been introduced by this
16949 dependent using-decl.
16950 FIXME: Track which members are introduced by a dependent
16951 using-decl precisely, perhaps by performing another lookup
16952 from the substituted USING_DECL_SCOPE. */
16955 }
16956 else
16958 }
16960 /* Returns true iff (a less specialized version of) FN appeared in
16961 the old lookup set OLDFNS. */
16964 /* FN is a member function from a base class, introduced via a
16965 using-decl; if it might have been introduced by a dependent
16966 using-decl then just conservatively keep it, otherwise look
16967 in the old lookup set for FN exactly. */
16970 /* FN is a member function template from the current class;
16971 look in the old lookup set for the TEMPLATE_DECL from which
16972 it was specialized. */
16974 else
16975 /* FN is a non-template member function from the current class;
16976 look in the old lookup set for the FUNCTION_DECL from which
16977 it was specialized. */
16980 };
16985 {
16988 }
16992 /* Filter out from NEWFNS the member functions that weren't
16993 previously visible according to OLDFNS. */
16998 {
17000 filtered_size++;
17001 }
17007 }
17009 /* tsubst a BASELINK. OBJECT_TYPE, if non-NULL, is the type of the
17010 expression on the left-hand side of the "." or "->" operator. We
17011 only do the lookup if we had a dependent BASELINK. Otherwise we
17012 adjust it onto the instantiated heirarchy. */
17014 static tree
17017 {
17029 {
17036 }
17044 {
17049 /* See maybe_dependent_member_ref. */
17051 {
17054 template_args);
17057 }
17060 /* Treat as-if non-dependent below. */
17065 complain);
17067 {
17068 /* Filter out from the new lookup set those functions which didn't
17069 appear in the original lookup set (in a less specialized form).
17070 This is needed to preserve the consistency of member lookup
17071 performed in an incomplete-class context, within which
17072 later-declared members ought to remain invisible. */
17075 binfo_type);
17077 }
17080 {
17086 }
17089 }
17090 else
17091 {
17092 /* We're going to overwrite pieces below, make a duplicate. */
17096 {
17097 /* The decl we found was from non-dependent scope, but we still need
17098 to update the binfos for the instantiated qualifying_scope. */
17102 }
17103 }
17105 /* If lookup found a single function, mark it as used at this point.
17106 (If lookup found multiple functions the one selected later by
17107 overload resolution will be marked as used at that point.) */
17109 {
17115 /* We might have instantiated an auto function. */
17117 }
17120 {
17121 /* Add back the template arguments, if present. */
17126 /* Update the conversion operator type. */
17128 }
17134 {
17136 qualifying_scope,
17137 object_type);
17139 /* We need to call adjust_result_of_qualified_name_lookup in case the
17140 destructor names a base class, but we unset BASELINK_QUALIFIED_P
17141 so that we still get virtual function binding. */
17143 }
17146 }
17148 /* Like tsubst_expr for a SCOPE_REF, given by QUALIFIED_ID. DONE is
17149 true if the qualified-id will be a postfix-expression in-and-of
17150 itself; false if more of the postfix-expression follows the
17151 QUALIFIED_ID. ADDRESS_P is true if the qualified-id is the operand
17152 of "&". */
17154 static tree
17158 {
17159 tree expr;
17160 tree scope;
17161 tree name;
17163 tree template_args;
17168 /* Figure out what name to look up. */
17171 {
17180 }
17181 else
17182 {
17185 }
17187 /* Substitute into the qualifying scope. When there are no ARGS, we
17188 are just trying to simplify a non-dependent expression. In that
17189 case the qualifying scope may be dependent, and, in any case,
17190 substituting will not help. */
17193 {
17196 }
17197 else
17201 {
17203 /* We built one in tsubst_baselink. */
17205 else
17206 {
17209 template_args);
17211 QUALIFIED_NAME_IS_TEMPLATE
17213 }
17216 }
17219 {
17221 {
17222 /* A BIT_NOT_EXPR is used to represent a destructor. */
17224 {
17228 }
17229 else
17232 }
17233 else
17237 {
17239 {
17243 }
17245 }
17246 }
17249 {
17253 /* Remember that there was a reference to this entity. */
17256 }
17259 {
17265 }
17268 {
17269 /* We may be repeating a check already done during parsing, but
17270 if it was well-formed and passed then, it will pass again
17271 now, and if it didn't, we wouldn't have got here. The case
17272 we want to catch is when we couldn't tell then, and can now,
17273 namely when templ prior to substitution was an
17274 identifier. */
17280 complain);
17281 else
17283 }
17289 {
17290 expr = (adjust_result_of_qualified_name_lookup
17292 expr = (finish_qualified_id_expr
17296 }
17298 /* Expressions do not generally have reference type. */
17300 /* However, if we're about to form a pointer-to-member, we just
17301 want the referenced member referenced. */
17311 }
17313 /* tsubst the initializer for a VAR_DECL. INIT is the unsubstituted
17314 initializer, DECL is the substituted VAR_DECL. Other arguments are as
17315 for tsubst. */
17317 static tree
17320 {
17329 {
17331 {
17333 {
17338 }
17339 }
17341 {
17342 /* If we had an initializer but it
17343 instantiated to nothing,
17344 value-initialize the object. This will
17345 only occur when the initializer was a
17346 pack expansion where the parameter packs
17347 used in that expansion were of length
17348 zero. */
17354 }
17355 }
17358 }
17360 /* If T is a reference to a dependent member of the current instantiation C and
17361 we are trying to refer to that member in a partial instantiation of C,
17362 return a SCOPE_REF; otherwise, return NULL_TREE.
17364 This can happen when forming a C++17 deduction guide, as in PR96199. */
17366 static tree
17368 tree in_decl)
17369 {
17386 {
17395 complain);
17396 }
17401 {
17407 }
17410 {
17413 /* The TYPE_DECL for a typename has DECL_CONTEXT of the typename
17414 scope, but it doesn't need to be rewritten again. */
17418 }
17422 else
17425 }
17427 /* Helper function for tsubst_omp_clauses, used for instantiation of
17428 OMP_CLAUSE_DECL of clauses. */
17430 static tree
17433 {
17437 /* Handle OpenMP iterators. */
17441 {
17442 tree ret;
17445 else
17446 {
17450 {
17464 }
17468 }
17472 }
17474 /* Handle an OpenMP array section represented as a TREE_LIST (or
17475 OMP_CLAUSE_DOACROSS_KIND). An OMP_CLAUSE_DOACROSS (with a depend
17476 kind of OMP_CLAUSE_DOACROSS_SINK) can also be represented as a
17477 TREE_LIST. We can handle it exactly the same as an array section
17478 (purpose, value, and a chain), even though the nomenclature
17479 (low_bound, length, etc) is different. */
17481 {
17482 tree low_bound
17495 }
17497 {
17498 tree low_bound
17501 in_decl);
17509 length);
17510 }
17512 /* Undo convert_from_reference tsubst_expr could have called. */
17518 }
17520 /* Like tsubst_copy, but specifically for OpenMP clauses. */
17522 static tree
17525 {
17531 {
17537 {
17540 {
17546 }
17547 /* FALLTHRU */
17577 /* FALLTHRU */
17611 {
17614 {
17621 }
17622 else
17624 }
17651 {
17654 }
17659 else
17690 }
17693 {
17710 /* tsubst_expr on SCOPE_REF results in returning
17711 finish_non_static_data_member result. Undo that here. */
17715 {
17720 {
17724 CASE_CONVERT:
17733 /* FALLTHRU */
17737 }
17738 }
17744 {
17747 {
17750 }
17751 }
17755 }
17756 }
17760 {
17765 {
17768 }
17769 }
17771 }
17773 /* Like tsubst_expr, but unshare TREE_LIST nodes. */
17775 static tree
17777 tree in_decl)
17778 {
17779 #define RECUR(t) tsubst_copy_asm_operands (t, args, complain, in_decl)
17797 {
17800 else
17801 {
17805 }
17806 }
17811 #undef RECUR
17812 }
17814 /* Used to temporarily communicate the list of #pragma omp parallel
17815 clauses to #pragma omp for instantiation if they are combined
17816 together. */
17821 cp_decomp *);
17823 /* Substitute one OMP_FOR iterator. */
17825 static bool
17829 {
17830 #define RECUR(NODE) \
17831 tsubst_stmt ((NODE), args, complain, in_decl)
17843 {
17846 {
17851 {
17860 else
17862 {
17864 {
17870 }
17873 }
17874 }
17875 }
17879 }
17881 {
17882 /* We need to jump through some hoops to handle declarations in the
17883 init-statement, since we might need to handle auto deduction,
17884 but we need to keep control of initialization. */
17888 }
17889 else
17890 {
17892 {
17895 {
17899 {
17903 CASE_CONVERT:
17911 {
17914 }
17915 /* FALLTHRU */
17919 }
17920 }
17921 }
17922 else
17924 }
17926 {
17932 }
17933 else
17937 {
17943 NULL_TREE);
17944 else
17946 }
17949 {
17957 {
17962 }
17965 }
17975 {
17977 {
17978 /* Declare the variable, but don't let that initialize it. */
17983 }
17986 {
17990 {
17999 }
18000 else
18004 {
18009 }
18010 else
18014 }
18020 }
18023 {
18024 /* Declare and initialize the variable. */
18027 }
18029 {
18034 {
18036 {
18042 {
18045 /* Move lastprivate (decl) clause to OMP_FOR_CLAUSES. */
18050 }
18053 {
18055 decl);
18057 }
18060 {
18062 decl);
18064 }
18065 else
18067 }
18070 }
18072 {
18075 ? OMP_CLAUSE_LASTPRIVATE
18080 {
18083 }
18084 }
18085 }
18088 {
18092 }
18093 else
18097 {
18108 {
18116 }
18117 else
18123 {
18129 }
18133 {
18141 }
18142 else
18148 }
18157 #undef RECUR
18158 }
18160 /* Helper function of tsubst_expr, find OMP_TEAMS inside
18161 of OMP_TARGET's body. */
18163 static tree
18165 {
18168 {
18177 }
18179 }
18181 /* Helper function for tsubst_expr. For decomposition declaration
18182 artificial base DECL, which is tsubsted PATTERN_DECL, tsubst
18183 also the corresponding decls representing the identifiers
18184 of the decomposition declaration. Return DECL if successful
18185 or error_mark_node otherwise, set *FIRST to the first decl
18186 in the list chained through DECL_CHAIN and *CNT to the number
18187 of such decls. */
18189 static tree
18192 {
18197 decl2
18202 {
18204 {
18207 }
18219 else
18220 {
18224 }
18231 {
18234 }
18235 else
18237 }
18240 }
18242 /* Return the proper local_specialization for init-capture pack DECL. */
18244 static tree
18246 {
18247 /* We handle normal pack captures by forwarding to the specialization of the
18248 captured parameter. We can't do that for pack init-captures; we need them
18249 to have their own local_specialization. We created the individual
18250 VAR_DECLs (if any) under build_capture_proxy, and we need to collect them
18251 when we process the DECL_EXPR for the pack init-capture in the template.
18252 So, how do we find them? We don't know the capture proxy pack when
18253 building the individual resulting proxies, and we don't know the
18254 individual proxies when instantiating the pack. What we have in common is
18255 the FIELD_DECL.
18257 So...when we instantiate the FIELD_DECL, we stick the result in
18258 local_specializations. Then at the DECL_EXPR we look up that result, see
18259 how many elements it has, synthesize the names, and look them up. */
18273 {
18278 }
18280 {
18285 else
18287 }
18289 }
18291 /* T is an operand of a template tree being substituted. Return whether
18292 T is dependent such that we should suppress some warnings that would
18293 make sense if the substituted expression were written directly, like
18294 template <int I> bool f() { return I == 2; }
18295 We don't want to warn when instantiating f that comparing two constants
18296 always has the same value.
18298 This is a more limited concept of dependence than instantiation-dependent;
18299 here we don't care whether substitution could fail. */
18301 static bool
18303 {
18312 }
18314 /* A superset of tsubst_expr that also handles statement trees. */
18316 static tree
18318 {
18319 #define RETURN(EXP) do { r = (EXP); goto out; } while(0)
18320 #define RECUR(NODE) \
18321 tsubst_stmt ((NODE), args, complain, in_decl)
18324 tree r;
18325 location_t loc;
18337 {
18339 {
18343 }
18362 else
18375 {
18380 }
18384 {
18386 tree init;
18392 {
18395 {
18399 {
18404 }
18406 }
18407 else
18408 {
18409 /* This is a non-dependent using-decl, and we'll have
18410 used the names it found during template parsing. We do
18411 not want to do the lookup again, because we might not
18412 find the things we found then. */
18415 /* We still need to push the bindings so that we can look up
18416 this name later. */
18419 }
18420 }
18423 {
18424 /* We're in tsubst_lambda_expr, we've already inserted a new
18425 capture proxy, so look it up and register it. */
18426 tree inst;
18428 {
18432 }
18434 {
18435 inst = (retrieve_local_specialization
18439 }
18440 else
18445 }
18452 /* Don't copy the old closure; we'll create a new one in
18453 tsubst_lambda_expr. */
18455 else
18456 {
18460 {
18461 /* By marking the declaration as instantiated, we avoid
18462 trying to instantiate it. Since instantiate_decl can't
18463 handle local variables, and since we've already done
18464 all that needs to be done, that's the right thing to
18465 do. */
18470 /* Anonymous aggregates are a special case. */
18473 {
18476 {
18480 }
18482 }
18487 {
18495 }
18496 else
18497 {
18512 {
18516 }
18521 const_init = (DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P
18524 /* In a non-template function, VLA type declarations are
18525 handled in grokdeclarator; for templates, handle them
18526 now. */
18530 {
18534 asmspec_tree
18538 }
18541 decomp);
18545 }
18546 }
18547 }
18550 }
18560 {
18564 }
18569 {
18570 /* Construct another range_for, if this is not a final
18571 substitution (for inside a generic lambda of a
18572 template). Otherwise convert to a regular for. */
18574 stmt = (processing_template_decl
18585 {
18589 }
18593 unroll
18595 unroll);
18597 {
18604 }
18605 else
18614 }
18621 {
18625 }
18631 {
18635 }
18647 {
18653 }
18656 {
18657 /* We're partially instantiating a generic lambda, but the condition
18658 of the constexpr if is still dependent. Don't substitute into the
18659 branches now, just remember the template arguments. */
18667 }
18671 {
18676 }
18677 else
18678 {
18686 }
18692 {
18702 }
18710 else
18718 else
18739 {
18745 {
18750 }
18751 }
18755 {
18757 tree label;
18764 }
18770 /* Computed goto's must be tsubst'd into. On the other hand,
18771 non-computed gotos must not be; the identifier in question
18772 will have no binding. */
18774 else
18780 {
18797 }
18802 {
18807 }
18808 else
18809 {
18814 else
18821 else
18827 else
18829 }
18833 {
18837 {
18839 /* Prevent instantiate_decl from trying to instantiate
18840 this variable. We've already done all that needs to be
18841 done. */
18844 }
18849 }
18855 {
18856 /* Local classes are not independent templates; they are
18857 instantiated along with their containing function. And this
18858 way we don't have to deal with pushing out of one local class
18859 to instantiate a member of another local class. */
18860 /* Closures are handled by the LAMBDA_EXPR. */
18864 {
18865 /* This is a partial instantiation, try again when full. */
18868 }
18882 }
18886 {
18903 }
18932 {
18939 }
18955 {
18969 in_decl);
18971 {
18978 }
18989 any_range_for
18996 {
19005 }
19006 else
19011 else
19018 else
19019 {
19027 }
19030 t));
19032 }
19038 /* FALLTHRU */
19048 in_decl);
19050 {
19055 }
19056 else
19057 {
19061 }
19066 {
19068 "%<#pragma omp critical%> with %<hint%> clause requires "
19071 }
19082 {
19085 {
19090 }
19091 else
19092 {
19096 }
19098 }
19099 else
19101 OMP_CLAUSE_DEPEND_INVALID,
19110 ? C_ORT_ACC
19129 {
19132 /* For combined target teams, ensure the num_teams and
19133 thread_limit clause expressions are evaluated on the host,
19134 before entering the target construct. */
19143 {
19146 tf_none);
19153 OMP_CLAUSE_FIRSTPRIVATE);
19157 }
19158 }
19195 {
19199 }
19200 else
19212 /* FALLTHRU */
19230 {
19236 {
19239 }
19241 {
19245 {
19248 }
19253 }
19254 else
19255 {
19258 }
19263 }
19264 else
19265 {
19272 {
19275 }
19278 {
19283 {
19286 }
19288 {
19292 {
19295 }
19300 }
19301 else
19302 {
19305 }
19309 }
19310 else
19311 {
19315 }
19319 }
19323 {
19329 {
19333 {
19338 }
19342 }
19343 else
19344 {
19349 }
19350 }
19354 {
19358 }
19371 /* If the first operand was a statement, we're done with it. */
19376 complain));
19385 }
19388 out:
19391 #undef RECUR
19392 #undef RETURN
19393 }
19395 /* Instantiate the special body of the artificial DECL_OMP_DECLARE_REDUCTION
19396 function. For description of the body see comment above
19397 cp_parser_omp_declare_reduction_exprs. */
19399 static void
19401 {
19407 tree_stmt_iterator tsi;
19418 {
19425 /* tsubsting a local var_decl leaves DECL_CONTEXT null, as we
19426 expect to be pushing it. */
19438 }
19440 {
19460 }
19461 }
19463 /* T is a postfix-expression that is not being used in a function
19464 call. Return the substituted version of T. */
19466 static tree
19468 tsubst_flags_t complain,
19469 tree in_decl)
19470 {
19474 else
19478 }
19480 /* Subroutine of tsubst_lambda_expr: add the FIELD/INIT capture pair to the
19481 LAMBDA_EXPR_CAPTURE_LIST passed in LIST. Do deduction for a previously
19482 dependent init-capture. EXPLICIT_P is true if the original list had
19483 explicit captures. */
19485 static void
19487 tsubst_flags_t complain)
19488 {
19490 {
19493 {
19497 }
19504 }
19507 }
19509 /* T is a LAMBDA_EXPR. Generate a new LAMBDA_EXPR for the current
19510 instantiation context. Instantiating a pack expansion containing a lambda
19511 might result in multiple lambdas all based on the same lambda in the
19512 template. */
19514 tree
19516 {
19530 else
19541 {
19546 else
19558 {
19559 /* For a VLA, simply tsubsting the field type won't work, we need to
19560 go through add_capture again. XXX do we want to do this for all
19561 captures? */
19562 tree name = (get_identifier
19571 }
19578 {
19579 /* Remember these for when we've pushed local_specializations. */
19582 }
19588 {
19597 complain);
19598 }
19599 else
19600 {
19606 }
19607 }
19616 /* If we're pushed into another scope (PR105652), fix it. */
19621 /* Do this again now that LAMBDA_EXPR_EXTRA_SCOPE is set. */
19638 {
19641 }
19644 {
19647 }
19651 else
19652 {
19653 /* The body of a lambda-expression is not a subexpression of the
19654 enclosing expression. Parms are to have DECL_CHAIN tsubsted,
19655 which would be skipped if cp_unevaluated_operand. */
19656 cp_evaluated ev;
19658 /* Fix the type of 'this'.
19659 For static and xobj member functions we use this to transport the
19660 lambda's closure type. It appears that in the regular case the
19661 object parameter is still pulled off, and then re-added again anyway.
19662 So perhaps we could do something better here? */
19666 tree inst = (oldtmpl
19671 {
19674 }
19680 /* Let finish_function set this. */
19686 else
19687 /* Still increment function_depth so that we don't GC in the
19688 middle of an expression. */
19698 /* Now record them for lookup_init_capture_pack. */
19701 {
19705 }
19711 {
19712 /* We might not partially instantiate some parts of the function, so
19713 copy these flags from the original template. */
19719 }
19721 /* [temp.deduct] A lambda-expression appearing in a function type or a
19722 template parameter is not considered part of the immediate context for
19723 the purposes of template argument deduction. */
19728 /* We already have a body block from start_lambda_function, we don't
19729 need another to confuse NRV (91217). */
19740 else
19743 /* The capture list was built up in reverse order; fix that now. */
19750 }
19752 out:
19758 }
19760 /* Subroutine of maybe_fold_fn_template_args. */
19762 static bool
19764 {
19767 {
19773 {
19776 }
19781 {
19785 }
19786 }
19789 }
19791 /* Try to do constant evaluation of any explicit template arguments in FN
19792 before overload resolution, to get any errors only once. Return true iff
19793 we didn't have any problems folding. */
19795 static bool
19797 {
19815 }
19817 /* Helper function for tsubst_expr CALL_EXPR and ARRAY_REF handling. */
19819 static void
19822 {
19825 {
19830 else
19831 {
19832 /* Expand the pack expansion and push each entry onto CALL_ARGS. */
19835 {
19840 {
19845 }
19846 }
19847 else
19848 /* A partial substitution. Add one entry. */
19850 }
19851 }
19852 }
19854 /* Like tsubst but deals with expressions and performs semantic
19855 analysis. */
19857 tree
19859 {
19860 #define RETURN(EXP) do { retval = (EXP); goto out; } while(0)
19861 #define RECUR(NODE) \
19862 tsubst_expr (NODE, args, complain, in_decl)
19865 location_t save_loc;
19874 /* N3276 decltype magic only applies to calls at the top level or on the
19875 right side of a comma. */
19879 /* This flag only applies to id-expressions at the top level, and
19880 controls resolution thereof. */
19889 {
19892 /* Fall through. */
19894 {
19895 tree decl;
19896 cp_id_kind idk;
19900 {
19903 }
19908 /* Look up the name. */
19911 /* By convention, expressions use ERROR_MARK_NODE to indicate
19912 failure, not NULL_TREE. */
19926 input_location);
19930 {
19934 }
19936 }
19939 {
19940 tree object;
19946 else
19955 {
19960 }
19963 {
19970 /* If we built a function concept check, return the underlying
19971 template-id. So we can evaluate it as a function call. */
19976 }
19979 {
19984 complain);
19988 }
19991 {
19994 }
19995 else
20007 {
20008 /* C++20 P0846: we can encounter an IDENTIFIER_NODE here when
20009 name lookup found nothing when parsing the template name. */
20012 }
20013 else
20015 }
20018 {
20022 {
20023 /* A type conversion to reference type will be enclosed in
20024 such an indirect ref, but the substitution of the cast
20025 will have also added such an indirect ref. */
20027 }
20028 else
20037 }
20040 {
20044 }
20047 {
20051 {
20056 }
20058 /* We'll pass this to convert_nontype_argument again, we don't need
20059 to actually perform any conversion here. */
20067 flags));
20068 }
20071 {
20077 }
20084 {
20085 tree type;
20099 {
20119 }
20122 }
20125 {
20129 }
20141 {
20144 }
20146 {
20150 }
20151 /* Fall through. */
20166 {
20173 }
20176 /* convert_like should have created an IMPLICIT_CONV_EXPR. */
20187 else
20189 in_decl);
20224 {
20225 /* If either OP0 or OP1 was value- or type-dependent, suppress
20226 warnings that depend on the range of the types involved. */
20240 tree r = build_x_binary_op
20242 op0,
20244 ? ERROR_MARK
20246 op1,
20248 ? ERROR_MARK
20257 }
20260 {
20268 }
20272 {
20277 }
20278 else
20292 {
20294 releasing_vec index_exp_list;
20297 tree r;
20303 else
20308 }
20314 {
20320 {
20324 }
20326 {
20330 }
20332 }
20337 {
20346 /* We only want to compute the number of arguments. */
20349 else
20356 {
20358 /* Set TREE_USED for the benefit of -Wunused. */
20362 }
20370 {
20373 else
20381 else
20386 }
20387 else
20389 }
20390 /* Fall through */
20393 {
20394 tree r;
20402 {
20403 /* When there are no ARGS, we are trying to evaluate a
20404 non-dependent expression from the parser. Trying to do
20405 the substitutions may not work. */
20408 }
20409 else
20410 {
20415 else
20419 }
20424 else
20429 {
20431 {
20433 {
20437 }
20438 else
20442 }
20444 }
20446 }
20449 {
20457 }
20471 {
20476 tree r = build_x_modify_expr
20480 /* TREE_NO_WARNING must be set if either the expression was
20481 parenthesized or it uses an operator such as >>= rather
20482 than plain assignment. In the former case, it was already
20483 set and must be copied. In the latter case,
20484 build_x_modify_expr sets it and it must not be reset
20485 here. */
20490 }
20495 /* Remember that there was a reference to this entity. */
20502 {
20507 tree ret;
20514 else
20515 {
20519 }
20521 /* If there was an initializer in the original tree, but it
20522 instantiated to an empty list, then we should pass a
20523 non-NULL empty vector to tell build_new that it was an
20524 empty initializer() rather than no initializer. This can
20525 only happen when the initializer is a pack expansion whose
20526 parameter packs are of length zero. */
20531 else
20532 {
20536 else
20537 {
20540 }
20541 }
20543 /* Avoid passing an enclosing decl to valid_array_size_p. */
20550 complain);
20558 }
20561 {
20567 complain));
20568 }
20571 {
20575 op0,
20579 }
20582 {
20583 tree function;
20587 tree ret;
20590 /* Internal function with no arguments. */
20594 /* When we parsed the expression, we determined whether or
20595 not Koenig lookup should be performed. */
20598 {
20601 }
20603 {
20608 }
20612 {
20614 in_decl);
20616 {
20623 }
20624 else
20627 }
20632 {
20633 /* Do nothing; calling tsubst_expr on an identifier
20634 would incorrectly perform unqualified lookup again.
20636 Note that we can also have an IDENTIFIER_NODE if the earlier
20637 unqualified lookup found a dependent local extern declaration
20638 (as per finish_call_expr); in that case koenig_p will be false
20639 and we do want to do the lookup again to find the substituted
20640 declaration. */
20645 }
20646 else
20647 {
20649 {
20655 }
20656 else
20661 /* Avoid error about taking the address of a constructor. */
20666 /* When KOENIG_P, we don't want to mark_used the callee before
20667 augmenting the overload set via ADL, so during this initial
20668 substitution we disable mark_used by setting tf_conv (68942). */
20674 }
20677 releasing_vec call_args;
20680 /* Stripped-down processing for a call in a thunk. Specifically, in
20681 the thunk template for a generic lambda. */
20683 {
20684 /* Now that we've expanded any packs, the number of call args
20685 might be different. */
20689 {
20696 }
20697 /* We aren't going to do normal overload resolution, so force the
20698 template-id to resolve. */
20701 {
20702 /* In a thunk, pass through args directly, without any
20703 conversions. */
20708 }
20710 {
20711 /* If there are no other args, just push 'this'. */
20714 else
20715 {
20716 /* Otherwise, shift the other args over to make room. */
20722 }
20723 }
20726 /* The thunk location is not interesting. */
20733 }
20735 /* We do not perform argument-dependent lookup if normal
20736 lookup finds a non-function, in accordance with the
20737 resolution of DR 218. */
20740 /* If lookup found a member function, the Koenig lookup is
20741 not appropriate, even if an unqualified-name was used
20742 to denote the function. */
20745 /* C++20 P0846: Lookup found nothing. */
20748 /* Only do this when substitution turns a dependent call
20749 into a non-dependent call. */
20761 {
20766 {
20767 /* For backwards compatibility and good diagnostics, try
20768 the unqualified lookup again if we aren't in SFINAE
20769 context. */
20775 {
20778 "and no declarations were found by "
20779 "argument-dependent lookup at the point "
20784 /* In a lambda fn, we have to be careful to not
20785 introduce new this captures. Legacy code can't
20786 be using lambdas anyway, so it's ok to be
20787 stricter. Be strict with C++20 template-id ADL too.
20788 And be strict if we're already failing anyway. */
20794 else
20798 {
20809 {
20812 "declarations in dependent base %qT are "
20818 else
20822 }
20823 else
20825 "%qD declared here, later in the "
20829 }
20832 }
20833 }
20835 {
20839 }
20840 }
20842 /* Remember that there was a reference to this entity. */
20851 /* Put back tf_decltype for the actual call. */
20856 {
20860 {
20862 "wrong number of arguments to "
20865 }
20866 else
20874 {
20876 "wrong number of arguments to "
20880 }
20884 complain);
20890 {
20892 complain);
20896 }
20901 {
20903 "wrong number of arguments to "
20906 }
20907 else
20908 {
20913 {
20916 }
20919 }
20923 /* Unsupported internal function with arguments. */
20925 }
20930 complain);
20932 {
20933 /* FUNCTION is a template-id referring to a concept definition. */
20938 /* Calls to standard and variable concepts should have been
20939 previously diagnosed. */
20942 /* Ensure the result is wrapped as a call expression. */
20944 }
20945 else
20948 koenig_p,
20949 complain);
20952 {
20958 {
20962 }
20964 /* This also suppresses -Wredundant-move. */
20966 }
20969 }
20972 {
20979 {
20981 {
20986 }
20987 else
20988 {
20993 }
20995 }
20996 else
20997 {
21000 }
21005 }
21008 {
21013 input_location));
21014 }
21020 {
21021 tree object;
21022 tree object_type;
21023 tree member;
21024 tree r;
21028 /* Remember that there was a reference to this entity. */
21039 else
21046 {
21049 }
21051 {
21053 complain);
21057 }
21061 {
21063 {
21068 {
21071 }
21073 {
21078 }
21079 }
21080 }
21083 {
21084 /* Lookup the template functions now that we know what the
21085 scope is. */
21092 {
21095 args);
21096 member = (adjust_result_of_qualified_name_lookup
21098 object_type));
21099 }
21100 else
21101 {
21103 input_location);
21105 }
21106 }
21110 {
21112 {
21116 else
21119 }
21121 }
21125 complain);
21129 }
21136 {
21143 tree r;
21152 /* We do not want to process the index of aggregate
21153 initializers as they are identifier nodes which will be
21154 looked up by digest_init. */
21158 {
21161 }
21166 {
21168 /* An identifier index is looked up in the type
21169 being initialized, not the current scope. */
21174 {
21175 /* Substitute into the pack expansion. */
21177 in_decl);
21181 ;
21183 /* Just move the argument into place. */
21185 else
21186 {
21187 /* Update the length of the final CONSTRUCTOR
21188 arguments vector, and note that we will need to
21189 copy.*/
21192 }
21193 }
21194 else
21196 }
21199 {
21204 {
21206 {
21211 }
21212 else
21214 }
21215 }
21223 {
21228 }
21232 }
21235 {
21238 {
21241 }
21242 else
21243 {
21246 }
21247 }
21254 tree r;
21259 {
21260 /* Local specialization will usually have been created when
21261 we instantiated the DECL_EXPR_DECL. */
21264 {
21265 /* We're in a generic lambda referencing a local extern
21266 from an outer block-scope of a non-template. */
21269 }
21270 }
21275 {
21277 {
21278 /* We get here for a use of 'this' in an NSDMI. */
21282 /* This can happen for a parameter name used later in a function
21283 declaration (such as in a late-specified return type). Just
21284 make a dummy decl, since it's only used for its type. */
21287 /* Give it the template pattern as its context; its true context
21288 hasn't been instantiated yet and this is good enough for
21289 mangling. */
21291 }
21293 {
21294 /* First try name lookup to find the instantiation. */
21297 {
21299 {
21300 /* During error-recovery we may find a non-variable,
21301 even an OVERLOAD: just bail out and avoid ICEs and
21302 duplicate diagnostics (c++/62207). */
21305 }
21307 {
21308 /* Make sure the one we found is the one we want. */
21312 }
21313 }
21317 else
21318 {
21319 /* This can happen for a variable used in a
21320 late-specified return type of a local lambda, or for a
21321 local static or constant. Building a new VAR_DECL
21322 should be OK in all those cases. */
21325 /* Avoid infinite recursion (79640). */
21328 {
21329 /* We can't call cp_finish_decl, so handle the
21330 initializer by hand. */
21345 }
21347 || processing_contract_condition
21354 }
21355 /* Remember this for subsequent uses. */
21358 }
21361 }
21362 else
21369 {
21370 /* ??? We're doing a subset of finish_id_expression here. */
21372 /* Replace an evaluated use of the thread_local variable with
21373 a call to its wrapper. */
21379 /* If the original type was a reference, we'll be wrapped in
21380 the appropriate INDIRECT_REF. */
21382 }
21386 {
21387 tree enum_type;
21388 tree v;
21395 /* Unfortunately, we cannot just call lookup_name here.
21396 Consider:
21398 template <int I> int f() {
21399 enum E { a = I };
21400 struct S { void g() { E e = a; } };
21401 };
21403 When we instantiate f<7>::S::g(), say, lookup_name is not
21404 clever enough to find f<7>::a. */
21405 enum_type
21415 /* We didn't find the name. That should never happen; if
21416 name-lookup found it during preliminary parsing, we
21417 should find it again here during instantiation. */
21420 }
21424 {
21425 tree ctx;
21430 {
21433 {
21437 }
21439 }
21440 }
21455 {
21456 /* Template template argument like the following example need
21457 special treatment:
21459 template <template <class> class TT> struct C {};
21460 template <class T> struct D {
21461 template <class U> struct E {};
21462 C<E> c; // #1
21463 };
21464 D<int> d; // #2
21466 We are processing the template argument `E' in #1 for
21467 the template instantiation #2. Originally, `E' is a
21468 TEMPLATE_DECL with `D<T>' as its DECL_CONTEXT. Now we
21469 have to substitute this with one having context `D<int>'. */
21474 }
21475 else
21476 /* Ordinary template template argument. */
21484 /* We shouldn't have built any of these during initial template
21485 generation. Instead, they should be built during instantiation
21486 in response to the saved STMT_IS_FULL_EXPR_P setting. */
21490 {
21500 }
21518 {
21519 /* Instantiate any typedefs in the type. */
21524 }
21527 {
21531 {
21534 }
21536 }
21539 /* These can sometimes show up in a partial instantiation, but never
21540 involve template parms. */
21556 /* ??? There's no point in copying it for now, but maybe some
21557 day it will contain more information, such as a pointer back
21558 to the containing function, inlined copy or so. */
21570 {
21574 }
21577 {
21578 tree object_ptr
21583 }
21590 {
21594 else
21600 }
21603 {
21612 /* If the resulting list of expression statement is empty,
21613 fold it further into void_node. */
21618 }
21621 {
21623 {
21624 /* We don't have a full set of template arguments yet; don't touch
21625 the lambda at all. */
21628 }
21632 }
21641 else
21642 /* Recreate the PAREN_EXPR from __builtin_assoc_barrier. */
21643 {
21647 }
21650 {
21655 complain));
21656 }
21659 {
21662 }
21665 /* No need to substitute further, a RANGE_EXPR will always be built
21666 with constant operands. */
21671 {
21675 /* We need to do this here as well as in tsubst_copy so we get the
21676 other tsubst_copy_and_build semantics for a PARM_DECL operand. */
21681 /* force_paren_expr can also create a VIEW_CONVERT_EXPR. */
21684 /* Otherwise, we're dealing with a wrapper to make a C++20 template
21685 parameter object const. */
21688 {
21689 /* The template argument is not const, presumably because
21690 it is still dependent, and so not the const template parm
21691 object. */
21695 {
21696 /* Don't add a wrapper to these. */
21699 }
21700 else
21701 /* Do add a wrapper otherwise (in particular, if op is
21702 another TEMPLATE_PARM_INDEX). */
21704 }
21706 }
21709 {
21716 op3);
21719 }
21722 /* Handle Objective-C++ constructs, if appropriate. */
21726 /* We shouldn't get here, but keep going if !flag_checking. */
21730 }
21732 #undef RECUR
21733 #undef RETURN
21734 out:
21737 }
21739 /* Verify that the instantiated ARGS are valid. For type arguments,
21740 make sure that the type's linkage is ok. For non-type arguments,
21741 make sure they are constants if they are integral or enumerations.
21742 Emit an error under control of COMPLAIN, and return TRUE on error. */
21744 static bool
21746 {
21750 {
21760 }
21762 {
21763 /* [basic.link]: A name with no linkage (notably, the name
21764 of a class or enumeration declared in a local scope)
21765 shall not be used to declare an entity with linkage.
21766 This implies that names with no linkage cannot be used as
21767 template arguments
21769 DR 757 relaxes this restriction for C++0x. */
21774 {
21775 /* DR 488 makes use of a type with no linkage cause
21776 type deduction to fail. */
21778 {
21781 else
21784 }
21786 }
21787 /* In order to avoid all sorts of complications, we do not
21788 allow variably-modified types as template arguments. */
21790 {
21794 }
21795 }
21796 /* Class template and alias template arguments should be OK. */
21798 ;
21799 /* A non-type argument of integral or enumerated type must be a
21800 constant. */
21805 {
21809 }
21811 }
21813 static bool
21815 {
21820 {
21823 }
21827 }
21829 /* Call mark_used on each entity within the non-type template arguments in
21830 ARGS for an instantiation of TMPL, to ensure that each such entity is
21831 considered odr-used (and therefore marked for instantiation) regardless of
21832 whether the specialization was first formed in a template context (which
21833 inhibits mark_used).
21835 This function assumes push_to_top_level has been called beforehand. */
21837 static void
21839 {
21840 /* It suffices to do this only when instantiating a primary template. */
21844 /* We already marked outer arguments when specializing the context. */
21848 {
21849 /* A (pointer/reference to) function or variable NTTP argument. */
21852 {
21858 {
21859 /* Pass tf_none to avoid duplicate diagnostics: if this call
21860 fails then an earlier call to mark_used for this argument
21861 must have also failed and emitted a diagnostic. */
21864 }
21865 }
21866 /* A class NTTP argument. */
21869 {
21872 {
21875 }
21877 };
21880 }
21881 }
21882 }
21884 /* We're out of SFINAE context now, so generate diagnostics for the access
21885 errors we saw earlier when instantiating D from TMPL and ARGS. */
21887 static void
21889 {
21901 }
21903 /* Instantiate the indicated variable, function, or alias template TMPL with
21904 the template arguments in TARG_PTR. */
21906 tree
21908 {
21912 tree fndecl;
21913 tree gen_tmpl;
21919 /* The other flags are not relevant anymore here, especially tf_partial
21920 shouldn't be set. For instance, we may be called while doing a partial
21921 substitution of a template variable, but the type of the variable
21922 template may be auto, in which case we will call do_auto_deduction
21923 in mark_used (which clears tf_partial) and the auto must be properly
21924 reduced at that time for the deduction to work. */
21932 /* If this function is a clone, handle it specially. */
21934 {
21935 tree spec;
21936 tree clone;
21938 /* Use DECL_ABSTRACT_ORIGIN because only FUNCTION_DECLs have
21939 DECL_CLONED_FUNCTION. */
21945 /* Look for the clone. */
21949 /* We should always have found the clone by now. */
21952 }
21957 /* Check to see if we already have this specialization. */
21961 /* targ_ptr only has the innermost template args, so add the outer ones
21962 from tmpl, which could be either a partial instantiation or gen_tmpl (in
21963 the case of a non-dependent call within a template definition). */
21964 targ_ptr = (add_outermost_template_args
21966 targ_ptr));
21972 || ((fndecl
21978 {
21980 {
21984 }
21986 }
21989 complain))
21992 /* We are building a FUNCTION_DECL, during which the access of its
21993 parameters and return types have to be checked. However this
21994 FUNCTION_DECL which is the desired context for access checking
21995 is not built yet. We solve this chicken-and-egg problem by
21996 deferring all checks until we have the FUNCTION_DECL. */
21999 /* Instantiation of the function happens in the context of the function
22000 template, not the context of the overload resolution we're doing. */
22002 /* If there are dependent arguments, e.g. because we're doing partial
22003 ordering, make sure processing_template_decl stays set. */
22007 {
22008 tree ctx;
22010 /* If the context of the partially instantiated template is
22011 already non-dependent, then we might as well use it. */
22013 else
22017 }
22024 {
22025 /* We need to determine if we're using a partial or explicit
22026 specialization now, because the type of the variable could be
22027 different. */
22033 {
22039 }
22040 }
22042 /* Substitute template parameters to obtain the specialization. */
22050 {
22053 }
22055 /* The DECL_TI_TEMPLATE should always be the immediate parent
22056 template, not the most general template. */
22060 /* Now that we we've formed this variable template specialization,
22061 remember the result of most_specialized_partial_spec for it. */
22070 /* Now we know the specialization, compute access previously
22071 deferred. Do no access control for inheriting constructors,
22072 as we already checked access for the inherited constructor. */
22075 {
22080 }
22083 /* If we've just instantiated the main entry point for a function,
22084 instantiate all the alternate entry points as well. We do this
22085 by cloning the instantiation of the main entry point, not by
22086 instantiating the template clones. */
22092 {
22094 {
22095 /* Remember to reinstantiate when we're out of SFINAE so the user
22096 can see the errors. */
22098 }
22100 }
22103 }
22105 /* Instantiate the alias template TMPL with ARGS. Also push a template
22106 instantiation level, which instantiate_template doesn't do because
22107 functions and variables have sufficient context established by the
22108 callers. */
22110 static tree
22112 {
22121 /* FIXME check for satisfaction in check_instantiated_args. */
22123 {
22125 {
22126 auto_diagnostic_group d;
22129 }
22131 }
22139 {
22140 /* An alias template specialization can be dependent
22141 even if its underlying type is not. */
22144 /* Sometimes a dependent alias spec is equivalent to its expansion,
22145 sometimes not. So always use structural_comptypes. */
22147 }
22150 }
22152 /* PARM is a template parameter pack for FN. Returns true iff
22153 PARM is used in a deducible way in the argument list of FN. */
22155 static bool
22157 {
22160 {
22162 tree packs;
22168 {
22169 /* The template parameter pack is used in a function parameter
22170 pack. If this is the end of the parameter list, the
22171 template parameter pack is deducible. */
22174 else
22175 /* Otherwise, not. Well, it could be deduced from
22176 a non-pack parameter, but doing so would end up with
22177 a deduction mismatch, so don't bother. */
22179 }
22180 }
22181 /* The template parameter pack isn't used in any function parameter
22182 packs, but it might be used deeper, e.g. tuple<Args...>. */
22184 }
22186 /* Subroutine of fn_type_unification: check non-dependent parms for
22187 convertibility. */
22189 static int
22194 {
22195 /* Non-constructor methods need to leave a conversion for 'this', which
22196 isn't included in nargs here. */
22202 {
22208 /* For a function parameter pack that occurs at the end of the
22209 parameter-declaration-list, the type A of each remaining
22210 argument of the call is compared with the type P of the
22211 declarator-id of the function parameter pack. */
22217 /* For a function parameter pack that does not occur at the
22218 end of the parameter-declaration-list, the type of the
22219 parameter pack is a non-deduced context. */
22223 {
22231 }
22234 }
22237 }
22239 /* The FN is a TEMPLATE_DECL for a function. ARGS is an array with
22240 NARGS elements of the arguments that are being used when calling
22241 it. TARGS is a vector into which the deduced template arguments
22242 are placed.
22244 Returns either a FUNCTION_DECL for the matching specialization of FN or
22245 NULL_TREE if no suitable specialization can be found. If EXPLAIN_P is
22246 true, diagnostics will be printed to explain why it failed.
22248 If FN is a conversion operator, or we are trying to produce a specific
22249 specialization, RETURN_TYPE is the return type desired.
22251 The EXPLICIT_TARGS are explicit template arguments provided via a
22252 template-id.
22254 The parameter STRICT is one of:
22256 DEDUCE_CALL:
22257 We are deducing arguments for a function call, as in
22258 [temp.deduct.call]. If RETURN_TYPE is non-null, we are
22259 deducing arguments for a call to the result of a conversion
22260 function template, as in [over.call.object].
22262 DEDUCE_CONV:
22263 We are deducing arguments for a conversion function, as in
22264 [temp.deduct.conv].
22266 DEDUCE_EXACT:
22267 We are deducing arguments when doing an explicit instantiation
22268 as in [temp.explicit], when determining an explicit specialization
22269 as in [temp.expl.spec], or when taking the address of a function
22270 template, as in [temp.deduct.funcaddr]. */
22272 tree
22274 tree explicit_targs,
22275 tree targs,
22278 tree return_type,
22279 unification_kind_t strict,
22284 {
22285 tree parms;
22286 tree fntype;
22291 /* type_unification_real will pass back any access checks from default
22292 template argument substitution. */
22294 /* We don't have all the template args yet. */
22307 full_targs = (add_outermost_template_args
22309 targs));
22314 /* In C++0x, it's possible to have a function template whose type depends
22315 on itself recursively. This is most obvious with decltype, but can also
22316 occur with enumeration scope (c++/48969). So we need to catch infinite
22317 recursion and reject the substitution at deduction time; this function
22318 will return error_mark_node for any repeated substitution.
22320 This also catches excessive recursion such as when f<N> depends on
22321 f<N-1> across all integers, and returns error_mark_node for all the
22322 substitutions back up to the initial one.
22324 This is, of course, not reentrant. */
22333 {
22334 /* [temp.deduct]
22336 The specified template arguments must match the template
22337 parameters in kind (i.e., type, nontype, template), and there
22338 must not be more arguments than there are parameters;
22339 otherwise type deduction fails.
22341 Nontype arguments must match the types of the corresponding
22342 nontype template parameters, or must be convertible to the
22343 types of the corresponding nontype parameters as specified in
22344 _temp.arg.nontype_, otherwise type deduction fails.
22346 All references in the function type of the function template
22347 to the corresponding template parameters are replaced by the
22348 specified template argument values. If a substitution in a
22349 template parameter or in the function type of the function
22350 template results in an invalid type, type deduction fails. */
22361 explicit_targs);
22363 /* Adjust any explicit template arguments before entering the
22364 substitution context. */
22365 explicit_targs
22372 /* Substitute the explicit args into the function type. This is
22373 necessary so that, for instance, explicitly declared function
22374 arguments can match null pointed constants. If we were given
22375 an incomplete set of explicit args, we must not do semantic
22376 processing during substitution as we could create partial
22377 instantiations. */
22379 {
22384 /* Dig out the actual parm. */
22387 {
22390 }
22392 {
22395 }
22398 /* No explicit argument for this template parameter. */
22401 {
22402 /* Mark the argument pack as "incomplete". We could
22403 still deduce more arguments during unification.
22404 We remove this mark in type_unification_real. */
22409 /* We have some incomplete argument packs. */
22411 }
22412 }
22415 {
22417 {
22420 }
22423 /* Ignore any access checks; we'll see them again in
22424 instantiate_template and they might have the wrong
22425 access path at this point. */
22436 }
22438 /* Place the explicitly specified arguments in TARGS. */
22444 SET_NON_DEFAULT_TEMPLATE_ARGS_COUNT
22446 }
22449 {
22455 }
22460 /* Never do unification on the 'this' parameter. */
22464 {
22465 /* We're deducing for a call to the result of a template conversion
22466 function. The parms we really want are in return_type. */
22470 }
22472 {
22474 }
22476 /* We allow incomplete unification without an error message here
22477 because the standard doesn't seem to explicitly prohibit it. Our
22478 callers must be ready to deal with unification failures in any
22479 event. */
22481 /* If we aren't explaining yet, push tinst context so we can see where
22482 any errors (e.g. from class instantiations triggered by instantiation
22483 of default template arguments) come from. If we are explaining, this
22484 context is redundant. */
22486 {
22489 }
22499 /* Now that we have bindings for all of the template arguments,
22500 ensure that the arguments deduced for the template template
22501 parameters have compatible template parameter lists. We cannot
22502 check this property before we have deduced all template
22503 arguments, because the template parameter types of a template
22504 template parameter might depend on prior template parameters
22505 deduced after the template template parameter. The following
22506 ill-formed example illustrates this issue:
22508 template<typename T, template<T> class C> void f(C<5>, T);
22510 template<int N> struct X {};
22512 void g() {
22513 f(X<5>(), 5l); // error: template argument deduction fails
22514 }
22516 The template parameter list of 'C' depends on the template type
22517 parameter 'T', but 'C' is deduced to 'X' before 'T' is deduced to
22518 'long'. Thus, we can't check that 'C' cannot bind to 'X' at the
22519 time that we deduce 'C'. */
22522 {
22525 }
22527 deduced:
22529 /* As a refinement of CWG2369, check first and foremost non-dependent
22530 conversions that we know are not going to induce template instantiation
22531 (PR99599). */
22533 && incomplete
22539 /* CWG2369: Check satisfaction before non-deducible conversions. */
22541 {
22545 }
22547 /* DR 1391: All parameters have args, now check non-dependent parms for
22548 convertibility. We don't do this if all args were explicitly specified,
22549 as the standard says that we substitute explicit args immediately. */
22556 /* All is well so far. Now, check:
22558 [temp.deduct]
22560 When all template arguments have been deduced, all uses of
22561 template parameters in nondeduced contexts are replaced with
22562 the corresponding deduced argument values. If the
22563 substitution results in an invalid type, as described above,
22564 type deduction fails. */
22566 {
22569 }
22571 /* Also collect access checks from the instantiation. */
22584 /* Now perform any access checks encountered during substitution. */
22591 /* If we're looking for an exact match, check that what we got
22592 is indeed an exact match. It might not be if some template
22593 parameters are used in non-deduced contexts. But don't check
22594 for an exact match if we have dependent template arguments;
22595 in that case we're doing partial ordering, and we already know
22596 that we have two candidates that will provide the actual type. */
22598 {
22602 tree sarg
22608 {
22612 }
22614 /* add_candidates uses DEDUCE_EXACT for x.operator foo(), but args
22615 doesn't contain the trailing void, and conv fns are always (). */
22617 {
22621 }
22622 }
22624 /* After doing deduction with the inherited constructor, actually return an
22625 instantiation of the inheriting constructor. */
22631 fail:
22634 {
22636 /* Reset once we're all the way out. */
22638 }
22641 }
22643 /* Returns true iff PARM is a forwarding reference in the context of
22644 template argument deduction for TMPL. */
22646 static bool
22648 {
22649 /* [temp.deduct.call], "A forwarding reference is an rvalue reference to a
22650 cv-unqualified template parameter ..." */
22655 {
22657 /* [temp.deduct.call], "... that does not represent a template parameter
22658 of a class template (during class template argument deduction)." */
22662 {
22663 /* Since the template parameters of a synthesized guide consist of
22664 the template parameters of the class template followed by those of
22665 the constructor (if any), we can tell if PARM represents a template
22666 parameter of the class template by comparing its index with the
22667 arity of the class template. */
22672 }
22674 }
22676 }
22678 /* Adjust types before performing type deduction, as described in
22679 [temp.deduct.call] and [temp.deduct.conv]. The rules in these two
22680 sections are symmetric. PARM is the type of a function parameter
22681 or the return type of the conversion function. ARG is the type of
22682 the argument passed to the call, or the type of the value
22683 initialized with the result of the conversion function.
22684 ARG_EXPR is the original argument expression, which may be null. */
22686 static int
22688 unification_kind_t strict,
22691 tree arg_expr)
22692 {
22696 {
22701 /* [temp.deduct.conv] First remove a reference type on parm.
22702 DRs 322 & 976 affected this. */
22706 /* Swap PARM and ARG throughout the remainder of this
22707 function; the handling is precisely symmetric since PARM
22708 will initialize ARG rather than vice versa. */
22714 /* Core issue #873: Do the DR606 thing (see below) for these cases,
22715 too, but here handle it by stripping the reference from PARM
22716 rather than by adding it to ARG. */
22721 /* Nothing else to do in this case. */
22726 }
22729 {
22730 /* [temp.deduct.call]
22732 If P is not a reference type:
22734 --If A is an array type, the pointer type produced by the
22735 array-to-pointer standard conversion (_conv.array_) is
22736 used in place of A for type deduction; otherwise,
22738 --If A is a function type, the pointer type produced by
22739 the function-to-pointer standard conversion
22740 (_conv.func_) is used in place of A for type deduction;
22741 otherwise,
22743 --If A is a cv-qualified type, the top level
22744 cv-qualifiers of A's type are ignored for type
22745 deduction. */
22750 else
22752 }
22754 /* [temp.deduct.call], "If P is a forwarding reference and the argument is
22755 an lvalue, the type 'lvalue reference to A' is used in place of A for
22756 type deduction." */
22759 /* try_one_overload doesn't provide an arg_expr, but
22760 functions are always lvalues. */
22764 /* [temp.deduct.call]
22766 If P is a cv-qualified type, the top level cv-qualifiers
22767 of P's type are ignored for type deduction. If P is a
22768 reference type, the type referred to by P is used for
22769 type deduction. */
22772 {
22775 }
22778 }
22780 /* Return true if computing a conversion from FROM to TO might induce template
22781 instantiation. Conversely, if this predicate returns false then computing
22782 the conversion definitely won't induce template instantiation. */
22784 static bool
22786 {
22793 {
22797 }
22799 /* If one of the types is a not-yet-instantiated class template
22800 specialization, then computing the conversion might instantiate
22801 it in order to inspect bases, conversion functions and/or
22802 converting constructors. */
22811 /* Converting from one pointer type to another, or between
22812 reference-related types, always yields a standard conversion. */
22816 /* Converting to a non-aggregate class type will consider its
22817 user-declared constructors, which might induce instantiation. */
22822 /* Similarly, converting from a class type will consider its conversion
22823 functions. */
22828 /* Otherwise, computing this conversion definitely won't induce
22829 template instantiation. */
22831 }
22833 /* Subroutine of fn_type_unification. PARM is a function parameter of a
22834 template which doesn't contain any deducible template parameters; check if
22835 ARG is a suitable match for it. STRICT, FLAGS and EXPLAIN_P are as in
22836 unify_one_argument. */
22838 static int
22842 {
22843 tree type;
22847 else
22855 {
22858 }
22860 {
22862 {
22863 /* This conversion was already computed earlier (when
22864 computing only non-instantiating conversions). */
22867 }
22876 /* Avoid recalculating this in add_function_candidate. */
22877 ok = (*conv_p
22879 else
22883 }
22887 else
22889 }
22893 /* Returns true iff the expression EXPR is one from which a template
22894 argument can be deduced. In other words, if it's an undecorated
22895 use of a template non-type parameter. */
22897 static bool
22899 {
22900 /* Strip implicit conversions and implicit INDIRECT_REFs. */
22906 }
22908 /* Returns true iff the array domain DOMAIN uses a template parameter in a
22909 deducible way; that is, if it has a max value of <PARM> - 1. */
22911 static bool
22913 {
22922 }
22924 /* Returns true iff the template arguments ARGS use a template parameter
22925 in a deducible way. */
22927 static bool
22929 {
22931 {
22935 else
22936 {
22943 else
22945 }
22948 }
22950 }
22952 /* Returns true iff TYPE contains any deducible references to template
22953 parameters, as per 14.8.2.5. */
22955 static bool
22957 {
22961 /* T
22962 cv-list T
22963 TT<T>
22964 TT<i>
22965 TT<> */
22970 /* T*
22971 T&
22972 T&& */
22976 /* T[integer-constant ]
22977 type [i] */
22982 /* T type ::*
22983 type T::*
22984 T T::*
22985 T (type ::*)()
22986 type (T::*)()
22987 type (type ::*)(T)
22988 type (T::*)(T)
22989 T (type ::*)(T)
22990 T (T::*)()
22991 T (T::*)(T) */
22994 || (uses_deducible_template_parms
22997 /* template-name <T> (where template-name refers to a class template)
22998 template-name <i> (where template-name refers to a class template) */
23005 /* type (T)
23006 T()
23007 T(T) */
23009 {
23023 }
23026 }
23028 /* Subroutine of type_unification_real and unify_pack_expansion to
23029 handle unification of a single P/A pair. Parameters are as
23030 for those functions. */
23032 static int
23036 {
23043 /* We can't deduce anything from this, but we might get all the
23044 template args from other function args. */
23047 /* Implicit conversions (Clause 4) will be performed on a function
23048 argument to convert it to the type of the corresponding function
23049 parameter if the parameter type contains no template-parameters that
23050 participate in template argument deduction. */
23053 /* For function parameters with no deducible template parameters,
23054 just return. We'll check non-dependent conversions later. */
23058 {
23060 arg_strict = (UNIFY_ALLOW_OUTER_LEVEL
23061 | UNIFY_ALLOW_MORE_CV_QUAL
23075 }
23077 /* We only do these transformations if this is the top-level
23078 parameter_type_list in a call or declaration matching; in other
23079 situations (nested function declarators, template argument lists) we
23080 won't be comparing a type to an expression, and we don't do any type
23081 adjustments. */
23083 {
23085 {
23088 {
23089 /* [temp.deduct.type] A template-argument can be
23090 deduced from a pointer to function or pointer
23091 to member function argument if the set of
23092 overloaded functions does not contain function
23093 templates and at most one of a set of
23094 overloaded functions provides a unique
23095 match. */
23099 /* If a unique match was not found, this is a
23100 non-deduced context, so we still succeed. */
23102 }
23108 }
23112 }
23113 else
23118 /* For deduction from an init-list we need the actual list. */
23122 }
23124 /* for_each_template_parm callback that always returns 0. */
23126 static int
23128 {
23130 }
23132 /* for_each_template_parm any_fn callback to handle deduction of a template
23133 type argument from the type of an array bound. */
23135 static int
23137 {
23145 {
23151 }
23153 /* Keep walking. */
23155 }
23157 /* Try to deduce any not-yet-deduced template type arguments from the type of
23158 an array bound. This is handled separately from unify because 14.8.2.5 says
23159 "The type of a type parameter is only deduced from an array bound if it is
23160 not otherwise deduced." */
23162 static void
23164 {
23169 }
23171 /* Most parms like fn_type_unification.
23173 If SUBR is 1, we're being called recursively (to unify the
23174 arguments of a function or method parameter of a function
23175 template).
23177 CHECKS is a pointer to a vector of access checks encountered while
23178 substituting default template arguments. */
23180 static int
23182 tree full_targs,
23183 tree xparms,
23187 unification_kind_t strict,
23190 {
23195 tree parms;
23206 /* Reset the number of non-defaulted template arguments contained
23207 in TARGS. */
23210 again:
23215 /* Only fn_type_unification cares about terminal void. */
23222 {
23227 /* For a function parameter pack that occurs at the end of the
23228 parameter-declaration-list, the type A of each remaining
23229 argument of the call is compared with the type P of the
23230 declarator-id of the function parameter pack. */
23236 /* For a function parameter pack that does not occur at the
23237 end of the parameter-declaration-list, the type of the
23238 parameter pack is a non-deduced context. */
23245 explain_p))
23247 }
23252 {
23253 /* Unify the remaining arguments with the pack expansion type. */
23254 tree argvec;
23257 /* Allocate a TREE_VEC and copy in all of the arguments */
23262 /* Copy the parameter into parmvec. */
23268 /* Advance to the end of the list of parameters. */
23270 }
23272 /* Fail if we've reached the end of the parm list, and more args
23273 are present, and the parm list isn't variadic. */
23276 /* Fail if parms are left and they don't have default values and
23277 they aren't all deduced as empty packs (c++/57397). This is
23278 consistent with sufficient_parms_p. */
23281 {
23285 do
23286 {
23289 count++;
23291 }
23295 type_pack_p);
23296 }
23299 {
23300 tsubst_flags_t complain = (explain_p
23301 ? tf_warning_or_error
23306 {
23310 /* Clear the "incomplete" flags on all argument packs now so that
23311 substituting them into later default arguments works. */
23313 {
23316 }
23324 {
23329 }
23331 /* If this is an undeduced nontype parameter that depends on
23332 a type parameter, try another pass; its type may have been
23333 deduced from a later argument than the one from which
23334 this parameter can be deduced. */
23339 {
23342 }
23344 /* Core issue #226 (C++0x) [temp.deduct]:
23346 If a template argument has not been deduced, its
23347 default template argument, if any, is used.
23349 When we are in C++98 mode, TREE_PURPOSE will either
23350 be NULL_TREE or ERROR_MARK_NODE, so we do not need
23351 to explicitly check cxx_dialect here. */
23353 /* OK, there is a default argument. Wait until after the
23354 conversion check to do substitution. */
23357 /* If the type parameter is a parameter pack, then it will
23358 be deduced to an empty parameter pack. */
23360 {
23361 tree arg;
23364 {
23367 }
23368 else
23375 }
23378 }
23380 /* During partial ordering, we deduce dependent template args. */
23383 /* Now substitute into the default template arguments. */
23385 {
23390 {
23394 }
23409 {
23410 /* The type of this non-type parameter depends on undeduced
23411 parameters. Don't try to use its default argument yet,
23412 since we might deduce an argument for it on the next pass,
23413 but do check whether the arguments we already have cause
23414 substitution failure, so that that happens before we try
23415 later default arguments (78489). */
23418 NULL_TREE);
23422 else
23424 }
23425 else
23426 {
23427 /* Even if the call is happening in template context, getting
23428 here means it's non-dependent, and a default argument is
23429 considered a separate definition under [temp.decls], so we can
23430 do this substitution without processing_template_decl. This
23431 is important if the default argument contains something that
23432 might be instantiation-dependent like access (87480). */
23436 {
23437 /* First instatiate in template context, in case we still
23438 depend on undeduced template parameters. */
23441 NULL_TREE);
23445 /* We replaced all the tparms, substitute again out of
23446 template context. */
23448 }
23451 NULL_TREE);
23460 }
23469 {
23471 /* The position of the first default template argument,
23472 is also the number of non-defaulted arguments in TARGS.
23473 Record that. */
23476 }
23477 }
23481 }
23487 }
23489 /* Subroutine of type_unification_real. Args are like the variables
23490 at the call site. ARG is an overloaded function (or template-id);
23491 we try deducing template args from each of the overloads, and if
23492 only one succeeds, we go with that. Modifies TARGS and returns
23493 true on success. */
23495 static bool
23497 tree targs,
23498 tree parm,
23499 tree arg,
23500 unification_kind_t strict,
23503 {
23510 {
23513 }
23514 else
23518 /* Handle `&x' where `x' is some static or non-static member
23519 function name. */
23525 /* Strip baselink information. */
23530 {
23531 /* If we got some explicit template args, we need to plug them into
23532 the affected templates before we try to unify, in case the
23533 explicit args will completely resolve the templates in question. */
23540 {
23551 {
23556 {
23557 /* Instantiate the function to deduce its return type. */
23561 }
23570 {
23573 }
23574 }
23577 }
23578 /* If no templates (or more than one) are fully resolved by the
23579 explicit arguments, this template-id is a non-deduced context; it
23580 could still be OK if we deduce all template arguments for the
23581 enclosing call through other arguments. */
23584 }
23586 /* If ARG is, for example, "(0, &f)" then its type will be unknown
23587 -- but the deduction does not succeed because the expression is
23588 not just the function on its own. */
23590 else
23592 {
23597 {
23600 }
23601 }
23603 /* [temp.deduct.type] A template-argument can be deduced from a pointer
23604 to function or pointer to member function argument if the set of
23605 overloaded functions does not contain function templates and at most
23606 one of a set of overloaded functions provides a unique match.
23608 So if we found multiple possibilities, we return success but don't
23609 deduce anything. */
23612 {
23616 {
23621 /* Don't forget explicit template arguments in a pack. */
23625 }
23626 }
23631 }
23633 /* Core DR 115: In contexts where deduction is done and fails, or in
23634 contexts where deduction is not done, if a template argument list is
23635 specified and it, along with any default template arguments, identifies
23636 a single function template specialization, then the template-id is an
23637 lvalue for the function template specialization. */
23639 tree
23641 {
23654 {
23657 }
23659 {
23662 }
23664 {
23667 }
23670 {
23674 /* If we got some explicit template args, we need to plug them into
23675 the affected templates before we try to unify, in case the
23676 explicit args will completely resolve the templates in question. */
23684 {
23695 {
23698 {
23701 }
23704 {
23707 }
23708 }
23709 }
23711 {
23719 {
23720 tree base
23723 }
23727 }
23729 /* There were no good options and at least one bad one, so let the
23730 user know what the problem is. */
23732 }
23734 }
23736 /* As above, but error out if the expression remains overloaded. */
23738 tree
23740 {
23743 {
23747 }
23749 }
23751 /* Subroutine of resolve_overloaded_unification; does deduction for a single
23752 overload. Fills TARGS with any deduced arguments, or error_mark_node if
23753 different overloads deduce different arguments for a given parm.
23754 ADDR_P is true if the expression for which deduction is being
23755 performed was of the form "& fn" rather than simply "fn".
23757 Returns 1 on success. */
23759 static int
23761 tree orig_targs,
23762 tree targs,
23763 tree parm,
23764 tree arg,
23765 unification_kind_t strict,
23769 {
23771 tree tempargs;
23777 /* [temp.deduct.type] A template-argument can be deduced from a pointer
23778 to function or pointer to member function argument if the set of
23779 overloaded functions does not contain function templates and at most
23780 one of a set of overloaded functions provides a unique match.
23782 So if this is a template, just return success. */
23795 /* We don't copy orig_targs for this because if we have already deduced
23796 some template args from previous args, unify would complain when we
23797 try to deduce a template parameter for the same argument, even though
23798 there isn't really a conflict. */
23805 /* First make sure we didn't deduce anything that conflicts with
23806 explicitly specified args. */
23808 {
23815 /* Since we're unifying against ourselves, we will fill in
23816 template args used in the function parm list with our own
23817 template parms. Discard them. */
23820 {
23821 /* Check that the argument at each index of the deduced argument pack
23822 is equivalent to the corresponding explicitly specified argument.
23823 We may have deduced more arguments than were explicitly specified,
23824 and that's OK. */
23826 /* We used to assert ARGUMENT_PACK_INCOMPLETE_P (oldelt) here, but
23827 that's wrong if we deduce the same argument pack from multiple
23828 function arguments: it's only incomplete the first time. */
23841 }
23844 }
23847 {
23852 }
23855 }
23857 /* PARM is a template class (perhaps with unbound template
23858 parameters). ARG is a fully instantiated type. If ARG can be
23859 bound to PARM, return ARG, otherwise return NULL_TREE. TPARMS and
23860 TARGS are as for unify. */
23862 static tree
23865 {
23873 /* We need to make a new template argument vector for the call to
23874 unify. If we used TARGS, we'd clutter it up with the result of
23875 the attempted unification, even if this class didn't work out.
23876 We also don't want to commit ourselves to all the unifications
23877 we've already done, since unification is supposed to be done on
23878 an argument-by-argument basis. In other words, consider the
23879 following pathological case:
23881 template <int I, int J, int K>
23882 struct S {};
23884 template <int I, int J>
23885 struct S<I, J, 2> : public S<I, I, I>, S<J, J, J> {};
23887 template <int I, int J, int K>
23888 void f(S<I, J, K>, S<I, I, I>);
23890 void g() {
23891 S<0, 0, 0> s0;
23892 S<0, 1, 2> s2;
23894 f(s0, s2);
23895 }
23897 Now, by the time we consider the unification involving `s2', we
23898 already know that we must have `f<0, 0, 0>'. But, even though
23899 `S<0, 1, 2>' is derived from `S<0, 0, 0>', the code is invalid
23900 because there are two ways to unify base classes of S<0, 1, 2>
23901 with S<I, I, I>. If we kept the already deduced knowledge, we
23902 would reject the possibility I=1. */
23910 else
23917 }
23919 /* Given a template type PARM and a class type ARG, find the unique
23920 base type in ARG that is an instance of PARM. We do not examine
23921 ARG itself; only its base-classes. If there is not exactly one
23922 appropriate base class, return NULL_TREE. PARM may be the type of
23923 a partial specialization, as well as a plain template type. Used
23924 by unify. */
23926 static enum template_base_result
23929 {
23931 tree binfo;
23937 {
23938 /* The type could not be completed. */
23941 }
23943 /* Walk in inheritance graph order. The search order is not
23944 important, and this avoids multiple walks of virtual bases. */
23946 {
23951 {
23952 /* If there is more than one satisfactory baseclass, then:
23954 [temp.deduct.call]
23956 If they yield more than one possible deduced A, the type
23957 deduction fails.
23959 applies. */
23961 {
23962 /* [temp.deduct.call]/4.3: If there is a class C that is a
23963 (direct or indirect) base class of D and derived (directly or
23964 indirectly) from a class B and that would be a valid deduced
23965 A, the deduced A cannot be B or pointer to B, respectively. */
23967 /* Ignore r. */
23971 else
23972 {
23975 }
23976 }
23979 }
23980 }
23984 }
23986 /* Returns the level of DECL, which declares a template parameter. */
23988 static int
23990 {
23992 {
24002 }
24004 }
24006 /* Decide whether ARG can be unified with PARM, considering only the
24007 cv-qualifiers of each type, given STRICT as documented for unify.
24008 Returns nonzero iff the unification is OK on that basis. */
24010 static int
24012 {
24018 {
24019 /* Although a CVR qualifier is ignored when being applied to a
24020 substituted template parameter ([8.3.2]/1 for example), that
24021 does not allow us to unify "const T" with "int&" because both
24022 types are not of the form "cv-list T" [14.8.2.5 temp.deduct.type].
24023 It is ok when we're allowing additional CV qualifiers
24024 at the outer level [14.8.2.1]/3,1st bullet. */
24033 }
24044 }
24046 /* Determines the LEVEL and INDEX for the template parameter PARM. */
24047 void
24049 {
24053 {
24056 }
24057 else
24058 {
24061 }
24062 }
24064 #define RECUR_AND_CHECK_FAILURE(TP, TA, P, A, S, EP) \
24065 do { \
24066 if (unify (TP, TA, P, A, S, EP)) \
24067 return 1; \
24068 } while (0)
24070 /* Unifies the remaining arguments in PACKED_ARGS with the pack
24071 expansion at the end of PACKED_PARMS. Returns 0 if the type
24072 deduction succeeds, 1 otherwise. STRICT is the same as in
24073 fn_type_unification. CALL_ARGS_P is true iff PACKED_ARGS is actually a
24074 function call argument list. We'll need to adjust the arguments to make them
24075 types. SUBR tells us if this is from a recursive call to
24076 type_unification_real, or for comparing two template argument
24077 lists. */
24079 static int
24083 {
24084 tree parm
24090 /* Add in any args remembered from an earlier partial instantiation. */
24098 /* Determine the parameter packs we will be deducing from the
24099 pattern, and record their current deductions. */
24102 {
24106 /* Only template parameter packs can be deduced, not e.g. function
24107 parameter packs or __bases or __integer_pack. */
24111 /* Determine the index and level of this parameter pack. */
24116 /* Keep track of the parameter packs and their corresponding
24117 argument packs. */
24120 }
24122 /* Loop through all of the arguments that have not yet been
24123 unified and unify each with the pattern. */
24125 {
24126 tree parm;
24130 /* For each parameter pack, set its TMPL_ARG to either NULL_TREE
24131 or the element of its argument pack at the current index if
24132 this argument was explicitly specified. */
24134 {
24143 {
24146 }
24148 }
24150 /* If we had explicit template arguments, substitute them into the
24151 pattern before deduction. */
24153 {
24154 /* Some arguments might still be unspecified or dependent. */
24162 NULL_TREE);
24167 }
24168 else
24171 /* Unify the pattern with the current argument. */
24173 explain_p))
24176 /* For each parameter pack, collect the deduced value. */
24178 {
24184 }
24185 }
24187 /* Verify that the results of unification with the parameter packs
24188 produce results consistent with what we've seen before, and make
24189 the deduced argument packs available. */
24191 {
24198 /* By default keep the original deduced argument pack.
24199 If necessary, more specific code is going to update the
24200 resulting deduced argument later down in this function. */
24204 /* If NEW_ARGS contains any NULL_TREE entries, we didn't
24205 actually deduce anything. */
24213 {
24214 /* If we had fewer function args than explicit template args,
24215 just use the explicits. */
24220 }
24223 {
24224 tree result;
24225 /* Build the deduced *_ARGUMENT_PACK. */
24227 {
24230 }
24231 else
24236 /* Note the deduced argument packs for this parameter
24237 pack. */
24239 }
24243 {
24244 /* We only had the explicitly-provided arguments before, but
24245 now we have a complete set of arguments. */
24251 }
24252 else
24253 {
24257 /* During template argument deduction for the aggregate deduction
24258 candidate, the number of elements in a trailing parameter pack
24259 is only deduced from the number of remaining function
24260 arguments if it is not otherwise deduced. */
24263 /* FIXME This isn't set properly for partial instantiations. */
24269 /* Inconsistent unification of this parameter pack. */
24271 bad_old_arg,
24272 bad_new_arg);
24273 }
24274 }
24277 }
24279 /* Handle unification of the domain of an array. PARM_DOM and ARG_DOM are
24280 INTEGER_TYPEs representing the TYPE_DOMAIN of ARRAY_TYPEs. The other
24281 parameters and return value are as for unify. */
24283 static int
24287 {
24288 tree parm_max;
24289 tree arg_max;
24293 /* Our representation of array types uses "N - 1" as the
24294 TYPE_MAX_VALUE for an array with "N" elements, if "N" is
24295 not an integer constant. We cannot unify arbitrarily
24296 complex expressions, so we eliminate the MINUS_EXPRs
24297 here. */
24301 {
24304 }
24308 {
24309 /* The ARG_MAX may not be a simple MINUS_EXPR, if we are
24310 trying to unify the type of a variable with the type
24311 of a template parameter. For example:
24313 template <unsigned int N>
24314 void f (char (&) [N]);
24315 int g();
24316 void h(int i) {
24317 char a[g(i)];
24318 f(a);
24319 }
24321 Here, the type of the ARG will be "int [g(i)]", and
24322 may be a SAVE_EXPR, etc. */
24326 }
24328 /* If only one of the bounds used a MINUS_EXPR, compensate
24329 by adding one to the other bound. */
24332 integer_type_node,
24333 parm_max,
24334 integer_one_node);
24337 integer_type_node,
24338 arg_max,
24339 integer_one_node);
24343 }
24345 /* Returns whether T, a P or A in unify, is a type, template or expression. */
24349 static pa_kind_t
24351 {
24360 else
24362 }
24364 /* Deduce the value of template parameters. TPARMS is the (innermost)
24365 set of template parameters to a template. TARGS is the bindings
24366 for those template parameters, as determined thus far; TARGS may
24367 include template arguments for outer levels of template parameters
24368 as well. PARM is a parameter to a template function, or a
24369 subcomponent of that parameter; ARG is the corresponding argument.
24370 This function attempts to match PARM with ARG in a manner
24371 consistent with the existing assignments in TARGS. If more values
24372 are deduced, then TARGS is updated.
24374 Returns 0 if the type deduction succeeds, 1 otherwise. The
24375 parameter STRICT is a bitwise or of the following flags:
24377 UNIFY_ALLOW_NONE:
24378 Require an exact match between PARM and ARG.
24379 UNIFY_ALLOW_MORE_CV_QUAL:
24380 Allow the deduced ARG to be more cv-qualified (by qualification
24381 conversion) than ARG.
24382 UNIFY_ALLOW_LESS_CV_QUAL:
24383 Allow the deduced ARG to be less cv-qualified than ARG.
24384 UNIFY_ALLOW_DERIVED:
24385 Allow the deduced ARG to be a template base class of ARG,
24386 or a pointer to a template base class of the type pointed to by
24387 ARG.
24388 UNIFY_ALLOW_INTEGER:
24389 Allow any integral type to be deduced. See the TEMPLATE_PARM_INDEX
24390 case for more information.
24391 UNIFY_ALLOW_OUTER_LEVEL:
24392 This is the outermost level of a deduction. Used to determine validity
24393 of qualification conversions. A valid qualification conversion must
24394 have const qualified pointers leading up to the inner type which
24395 requires additional CV quals, except at the outer level, where const
24396 is not required [conv.qual]. It would be normal to set this flag in
24397 addition to setting UNIFY_ALLOW_MORE_CV_QUAL.
24398 UNIFY_ALLOW_OUTER_MORE_CV_QUAL:
24399 This is the outermost level of a deduction, and PARM can be more CV
24400 qualified at this point.
24401 UNIFY_ALLOW_OUTER_LESS_CV_QUAL:
24402 This is the outermost level of a deduction, and PARM can be less CV
24403 qualified at this point. */
24405 static int
24408 {
24410 tree targ;
24411 tree tparm;
24413 tsubst_flags_t complain = (explain_p
24414 ? tf_warning_or_error
24417 /* I don't think this will do the right thing with respect to types.
24418 But the only case I've seen it in so far has been array bounds, where
24419 signedness is the only information lost, and I think that will be
24420 okay. VIEW_CONVERT_EXPR can appear with class NTTP, thanks to
24421 finish_id_expression_1, and are also OK. */
24429 /* We can't deduce anything from this, but we might get all the
24430 template args from other function args. */
24436 /* If PARM uses template parameters, then we can't bail out here,
24437 even if ARG == PARM, since we won't record unifications for the
24438 template parameters. We might need them if we're trying to
24439 figure out which of two things is more specialized. */
24444 /* Handle init lists early, so the rest of the function can assume
24445 we're dealing with a type. */
24447 {
24448 tree elttype;
24453 /* We can only deduce from an initializer list argument if the
24454 parameter is std::initializer_list or an array; otherwise this
24455 is a non-deduced context. */
24460 else
24461 {
24463 /* Deduction is defined in terms of a single type, so just punt
24464 on the (bizarre) std::initializer_list<T...>. */
24467 }
24472 /* If ELTTYPE has no deducible template parms, skip deduction from
24474 else
24476 {
24484 {
24488 /* It should only be possible to get here for a call. */
24490 elt_strict |= maybe_adjust_types_for_deduction
24493 }
24496 explain_p);
24497 }
24501 {
24502 /* Also deduce from the length of the initializer list. */
24509 }
24511 /* If the std::initializer_list<T> deduction worked, replace the
24512 deduced A with std::initializer_list<A>. */
24514 {
24519 }
24521 }
24523 /* If parm and arg aren't the same kind of thing (template, type, or
24524 expression), fail early. */
24528 /* Immediately reject some pairs that won't unify because of
24529 cv-qualification mismatches. */
24532 /* It is the elements of the array which hold the cv quals of an array
24533 type, and the elements might be template type parms. We'll check
24534 when we recurse. */
24536 /* We check the cv-qualifiers when unifying with template type
24537 parameters below. We want to allow ARG `const T' to unify with
24538 PARM `T' for example, when computing which of two templates
24539 is more specialized, for example. */
24548 /* PMFs recurse at the same level, so don't strip this yet. */
24556 {
24560 /* In a type which contains a nested-name-specifier, template
24561 argument values cannot be deduced for template parameters used
24562 within the nested-name-specifier. */
24574 /* The PARM is not one we're trying to unify. Just check
24575 to see if it matches ARG. */
24576 {
24581 else
24583 }
24590 /* Check for mixed types and values. */
24598 {
24601 {
24602 /* First try to match ARG directly. */
24604 explain_p);
24606 {
24607 /* Otherwise, look for a suitable base of ARG, as below. */
24614 }
24615 }
24616 /* ARG must be constructed from a template class or a template
24617 template parameter. */
24622 /* Deduce arguments T, i from TT<T> or TT<i>. */
24628 /* If the template is a template template parameter, use the
24629 TEMPLATE_TEMPLATE_PARM for matching. */
24632 /* Fall through to deduce template name. */
24633 }
24637 {
24638 /* Deduce template name TT from TT, TT<>, TT<T> and TT<i>. */
24640 /* Simple cases: Value already set, does match or doesn't. */
24645 }
24646 else
24647 {
24648 /* If PARM is `const T' and ARG is only `int', we don't have
24649 a match unless we are allowing additional qualification.
24650 If ARG is `const int' and PARM is just `T' that's OK;
24651 that binds `const int' to `T'. */
24656 /* Consider the case where ARG is `const volatile int' and
24657 PARM is `const T'. Then, T should be `volatile int'. */
24658 arg = cp_build_qualified_type
24663 /* Simple cases: Value already set, does match or doesn't. */
24669 /* Make sure that ARG is not a variable-sized array. (Note
24670 that were talking about variable-sized arrays (like
24671 `int[n]'), rather than arrays of unknown size (like
24672 `int[]').) We'll get very confused by such a type since
24673 the bound of the array is not constant, and therefore
24674 not mangleable. Besides, such types are not allowed in
24675 ISO C++, so we can do as we please here. We do allow
24676 them for 'auto' deduction, since that isn't ABI-exposed. */
24680 /* Strip typedefs as in convert_template_argument. */
24682 }
24684 /* If ARG is a parameter pack or an expansion, we cannot unify
24685 against it unless PARM is also a parameter pack. */
24690 /* If the argument deduction results is a METHOD_TYPE,
24691 then there is a problem.
24692 METHOD_TYPE doesn't map to any real C++ type the result of
24693 the deduction cannot be of that type. */
24707 {
24708 /* The PARM is not one we're trying to unify. Just check
24709 to see if it matches ARG. */
24715 }
24721 {
24725 /* We're deducing from an array bound, the type doesn't matter.
24726 This conversion should match the one below. */
24732 }
24734 /* [temp.deduct.type] If, in the declaration of a function template
24735 with a non-type template-parameter, the non-type
24736 template-parameter is used in an expression in the function
24737 parameter-list and, if the corresponding template-argument is
24738 deduced, the template-argument type shall match the type of the
24739 template-parameter exactly, except that a template-argument
24740 deduced from an array bound may be of any integral type.
24741 The non-type parameter might use already deduced type parameters. */
24744 /* We don't have enough levels of args to do any substitution. This
24746 else
24747 {
24753 {
24756 LOOKUP_NORMAL,
24760 }
24761 }
24765 /* Template-parameter dependent expression. Just accept it for now.
24766 It will later be processed in convert_template_argument. */
24767 ;
24771 /* OK. Ignore top-level quals here because a class-type template
24775 /* Convert the ARG to the type of PARM; the deduced non-type
24776 template argument must exactly match the types of the
24777 corresponding parameter. This conversion should match the
24778 one above. */
24781 {
24782 /* We haven't deduced the type of this parameter yet. */
24784 /* We deduce from array bounds in try_array_deduction. */
24787 {
24788 /* Deduce it from the non-type argument. As above, ignore
24789 top-level quals here too. */
24794 /* Now check whether the type of this parameter is still
24795 dependent, and give up if so. */
24801 }
24802 else
24803 /* Try again later. */
24805 }
24806 else
24809 /* If ARG is a parameter pack or an expansion, we cannot unify
24810 against it unless PARM is also a parameter pack. */
24815 {
24818 }
24823 {
24824 /* A pointer-to-member constant can be unified only with
24825 another constant. */
24829 /* Just unify the class member. It would be useless (and possibly
24830 wrong, depending on the strict flags) to unify also
24831 PTRMEM_CST_CLASS, because we want to be sure that both parm and
24832 arg refer to the same variable, even if through different
24833 classes. For instance:
24835 struct A { int x; };
24836 struct B : A { };
24838 Unification of &A::x and &B::x must succeed. */
24841 }
24844 {
24848 /* [temp.deduct.call]
24850 A can be another pointer or pointer to member type that can
24851 be converted to the deduced A via a qualification
24852 conversion (_conv.qual_).
24854 We pass down STRICT here rather than UNIFY_ALLOW_NONE.
24855 This will allow for additional cv-qualification of the
24856 pointed-to types if appropriate. */
24859 /* The derived-to-base conversion only persists through one
24860 level of pointers. */
24865 }
24898 /* We have already checked cv-qualification at the top of the
24899 function. */
24903 /* As far as unification is concerned, this wins. Later checks
24904 will invalidate it if necessary. */
24907 /* Types INTEGER_CST and MINUS_EXPR can come from array bounds. */
24908 /* Type INTEGER_CST can come from ordinary constant template args. */
24923 {
24933 /* Check for pack expansions in the parameters. */
24935 {
24937 {
24939 /* We can unify against something with a trailing
24940 parameter pack. */
24942 else
24943 /* [temp.deduct.type]/9: If the template argument list of
24944 P contains a pack expansion that is not the last
24945 template argument, the entire template argument list
24946 is a non-deduced context. */
24948 }
24949 }
24951 /* If we don't have enough arguments to satisfy the parameters
24952 (not counting the pack expression at the end), or we have
24953 too many arguments for a parameter list that doesn't end in
24954 a pack expression, we can't unify. */
24960 /* Unify all of the parameters that precede the (optional)
24961 pack expression. */
24963 {
24968 }
24971 DEDUCE_EXACT,
24974 }
24982 {
24990 }
24995 {
24999 {
25000 /* First, we try to unify the PARM and ARG directly. */
25005 {
25006 /* Fallback to the special case allowed in
25007 [temp.deduct.call]:
25009 If P is a class, and P has the form
25010 template-id, then A can be a derived class of
25011 the deduced A. Likewise, if P is a pointer to
25012 a class of the form template-id, A can be a
25013 pointer to a derived class pointed to by the
25014 deduced A. */
25020 {
25021 /* Don't give the derived diagnostic if we're
25022 already dealing with the same template. */
25023 bool same_template
25029 }
25030 }
25031 }
25035 /* Perhaps PARM is something like S<U> and ARG is S<int>.
25036 Then, we should unify `int' and `U'. */
25038 else
25039 /* There's no chance of unification succeeding. */
25047 else
25049 }
25056 {
25059 tree a;
25065 /* CV qualifications for methods can never be deduced, they must
25066 match exactly. We need to check them explicitly here,
25067 because type_unification_real treats them as any other
25068 cv-qualified parameter. */
25070 && (!check_cv_quals_for_unify
25098 {
25108 else
25109 {
25112 /* Here "less cv-qual" means the deduced arg (i.e. parm) has
25113 /more/ noexcept, since function pointer conversions are the
25114 reverse of qualification conversions. */
25119 else
25121 }
25122 }
25124 {
25125 /* As for noexcept. */
25132 else
25134 }
25137 }
25140 /* Unify a pointer to member with a pointer to member function, which
25141 deduces the type of the member as a function type. */
25143 {
25144 /* Check top-level cv qualifiers */
25152 /* Determine the type of the function we are unifying against. */
25156 }
25167 /* CONST_DECL should already have been folded to its DECL_INITIAL. */
25173 /* Matched cases are handled by the ARG == PARM test above. */
25177 /* We might get a variable as a non-type template argument in parm if the
25178 corresponding parameter is type-dependent. Make any necessary
25179 adjustments based on whether arg is a reference. */
25183 {
25188 }
25189 /* Now use the normal expression code to check whether they match. */
25200 /* Cannot deduce anything from TYPEOF_TYPE, DECLTYPE_TYPE,
25201 or TRAIT_TYPE nodes. */
25205 /* Unification fails if we hit an error node. */
25210 {
25220 }
25221 /* FALLTHRU */
25224 /* An unresolved overload is a nondeduced context. */
25230 expr:
25231 /* We must be looking at an expression. This can happen with
25232 something like:
25234 template <int I>
25235 void foo(S<I>, S<I + 2>);
25237 or
25239 template<typename T>
25240 void foo(A<T, T{}>);
25242 This is a "non-deduced context":
25244 [deduct.type]
25246 The non-deduced contexts are:
25248 --A non-type template argument or an array bound in which
25249 a subexpression references a template parameter.
25251 In these cases, we assume deduction succeeded, but don't
25252 actually infer any unifications. */
25257 else
25259 }
25260 }
25261 #undef RECUR_AND_CHECK_FAILURE
25262 \f
25263 /* Note that DECL can be defined in this translation unit, if
25264 required. */
25266 static void
25268 {
25269 tree clone;
25273 }
25275 /* Called if RESULT is explicitly instantiated, or is a member of an
25276 explicitly instantiated class. */
25278 void
25280 {
25283 /* If this entity has already been written out, it's too late to
25284 make any modifications. */
25288 /* consteval functions are never emitted. */
25293 /* For anonymous namespace we don't need to do anything. */
25295 {
25298 }
25301 /* The TREE_PUBLIC flag for function declarations will have been
25302 set correctly by tsubst. */
25306 {
25309 }
25310 else
25311 {
25314 /* Always make artificials weak. */
25317 /* For WIN32 we also want to put explicit instantiations in
25318 linkonce sections. */
25323 /* If the function has already been instantiated, clear DECL_EXTERNAL,
25324 since start_preparsed_function wouldn't have if we had an earlier
25325 extern explicit instantiation. */
25327 }
25329 /* If EXTERN_P, then this function will not be emitted -- unless
25330 followed by an explicit instantiation, at which point its linkage
25331 will be adjusted. If !EXTERN_P, then this function will be
25332 emitted here. In neither circumstance do we want
25333 import_export_decl to adjust the linkage. */
25335 }
25337 /* Subroutine of more_specialized_fn: check whether TARGS is missing any
25338 important template arguments. If any are missing, we check whether
25339 they're important by using error_mark_node for substituting into any
25340 args that were used for partial ordering (the ones between ARGS and END)
25341 and seeing if it bubbles up. */
25343 static bool
25345 {
25349 {
25352 }
25354 {
25358 }
25360 }
25362 /* Given two function templates PAT1 and PAT2, return:
25364 1 if PAT1 is more specialized than PAT2 as described in [temp.func.order].
25365 -1 if PAT2 is more specialized than PAT1.
25366 0 if neither is more specialized.
25368 LEN indicates the number of parameters we should consider
25369 (defaulted parameters should not be considered).
25371 The 1998 std underspecified function template partial ordering, and
25372 DR214 addresses the issue. We take pairs of arguments, one from
25373 each of the templates, and deduce them against each other. One of
25374 the templates will be more specialized if all the *other*
25375 template's arguments deduce against its arguments and at least one
25376 of its arguments *does* *not* deduce against the other template's
25377 corresponding argument. Deduction is done as for class templates.
25378 The arguments used in deduction have reference and top level cv
25379 qualifiers removed. Iff both arguments were originally reference
25380 types *and* deduction succeeds in both directions, an lvalue reference
25381 wins against an rvalue reference and otherwise the template
25382 with the more cv-qualified argument wins for that pairing (if
25383 neither is more cv-qualified, they both are equal). Unlike regular
25384 deduction, after all the arguments have been deduced in this way,
25385 we do *not* verify the deduced template argument values can be
25386 substituted into non-deduced contexts.
25388 The logic can be a bit confusing here, because we look at deduce1 and
25389 targs1 to see if pat2 is at least as specialized, and vice versa; if we
25390 can find template arguments for pat1 to make arg1 look like arg2, that
25391 means that arg2 is at least as specialized as arg1. */
25393 int
25395 {
25408 /* C++17 [temp.func.order]/3 (CWG532)
25410 If only one of the function templates M is a non-static member of some
25411 class A, M is considered to have a new first parameter inserted in its
25412 function parameter list. Given cv as the cv-qualifiers of M (if any), the
25413 new parameter is of type "rvalue reference to cv A" if the optional
25414 ref-qualifier of M is && or if M has no ref-qualifier and the first
25415 parameter of the other template has rvalue reference type. Otherwise, the
25416 new parameter is of type "lvalue reference to cv A". */
25419 {
25420 /* Note C++20 DR2445 extended the above to static member functions, but
25421 I think think the old G++ behavior of just skipping the object
25422 parameter when comparing to a static member function was better, so
25423 let's stick with that for now. This is CWG2834. --jason 2023-12 */
25425 {
25428 }
25431 }
25434 {
25435 /* Note DR2445 also (IMO wrongly) removed the "only one" above, which
25436 would break e.g. cpp1y/lambda-generic-variadic5.C. */
25437 len--;
25440 }
25443 {
25444 /* The other is a non-member or explicit object member function;
25445 rewrite the implicit object parameter to a reference. */
25454 {
25460 }
25463 }
25465 /* If only one is a conversion operator, they are unordered. */
25469 /* Consider the return type for a conversion function */
25471 {
25474 len++;
25475 }
25477 processing_template_decl++;
25483 /* Stop when an ellipsis is seen. */
25485 {
25496 {
25497 /* When both arguments are pack expansions, we need only
25498 unify the patterns themselves. */
25502 /* This is the last comparison we need to do. */
25504 }
25507 {
25511 }
25514 {
25518 }
25524 {
25530 /* Setup the parameter vector, which contains only ARG1. */
25533 /* Setup the argument vector, which contains the remaining
25534 arguments. */
25543 /* We cannot deduce in the other direction, because ARG1 is
25544 a pack expansion but ARG2 is not. */
25546 }
25548 {
25554 /* Setup the parameter vector, which contains only ARG1. */
25557 /* Setup the argument vector, which contains the remaining
25558 arguments. */
25567 /* We cannot deduce in the other direction, because ARG2 is
25568 a pack expansion but ARG1 is not.*/
25570 }
25572 else
25573 {
25574 /* The normal case, where neither argument is a pack
25575 expansion. */
25582 }
25584 /* If we couldn't deduce arguments for tparms1 to make arg1 match
25585 arg2, then arg2 is not as specialized as arg1. */
25591 /* "If, for a given type, deduction succeeds in both directions
25592 (i.e., the types are identical after the transformations above)
25593 and both P and A were reference types (before being replaced with
25594 the type referred to above):
25595 - if the type from the argument template was an lvalue reference and
25596 the type from the parameter template was not, the argument type is
25597 considered to be more specialized than the other; otherwise,
25598 - if the type from the argument template is more cv-qualified
25599 than the type from the parameter template (as described above),
25600 the argument type is considered to be more specialized than the other;
25601 otherwise,
25602 - neither type is more specialized than the other." */
25605 {
25607 {
25610 else
25612 }
25614 {
25619 }
25620 }
25623 /* We've failed to deduce something in either direction.
25624 These must be unordered. */
25629 /* We have already processed all of the arguments in our
25630 handing of the pack expansion type. */
25635 }
25637 /* "In most cases, all template parameters must have values in order for
25638 deduction to succeed, but for partial ordering purposes a template
25639 parameter may remain without a value provided it is not used in the
25640 types being used for partial ordering."
25642 Thus, if we are missing any of the targs1 we need to substitute into
25643 origs1, then pat2 is not as specialized as pat1. This can happen when
25644 there is a nondeduced context. */
25650 processing_template_decl--;
25652 /* If both deductions succeed, the partial ordering selects the more
25653 constrained template. */
25654 /* P2113: If the corresponding template-parameters of the
25655 template-parameter-lists are not equivalent ([temp.over.link]) or if
25656 the function parameters that positionally correspond between the two
25657 templates are not of the same type, neither template is more
25658 specialized than the other. */
25663 {
25669 }
25671 /* All things being equal, if the next argument is a pack expansion
25672 for one function but not for the other, prefer the
25673 non-variadic function. FIXME this is bogus; see c++/41958. */
25677 {
25680 }
25686 else
25688 }
25690 /* Determine which of two partial specializations of TMPL is more
25691 specialized.
25693 PAT1 is a TREE_LIST whose TREE_VALUE is the TEMPLATE_DECL corresponding
25694 to the first partial specialization. The TREE_PURPOSE is the
25695 innermost set of template parameters for the partial
25696 specialization. PAT2 is similar, but for the second template.
25698 Return 1 if the first partial specialization is more specialized;
25699 -1 if the second is more specialized; 0 if neither is more
25700 specialized.
25702 See [temp.class.order] for information about determining which of
25703 two templates is more specialized. */
25705 static int
25707 {
25708 tree targs;
25717 /* Just like what happens for functions, if we are ordering between
25718 different template specializations, we may encounter dependent
25719 types in the arguments, and we need our dependency check functions
25720 to behave correctly. */
25724 {
25727 }
25731 {
25734 }
25737 /* If both deductions succeed, the partial ordering selects the more
25738 constrained template. */
25742 /* In the case of a tie where at least one of the templates
25743 has a parameter pack at the end, the template with the most
25744 non-packed parameters wins. */
25746 && any_deductions
25749 {
25755 /* We don't count the pack expansion at the end. */
25765 }
25768 }
25770 /* Return the template arguments that will produce the function signature
25771 DECL from the function template FN, with the explicit template
25772 arguments EXPLICIT_ARGS. If CHECK_RETTYPE is true, the return type must
25773 also match. Return NULL_TREE if no satisfactory arguments could be
25774 found. */
25776 static tree
25778 {
25782 tree decl_arg_types;
25785 tree arg;
25789 /* Never do unification on the 'this' parameter. */
25811 }
25813 /* Return the innermost template arguments that, when applied to a partial
25814 specialization SPEC_TMPL of TMPL, yield the ARGS.
25816 For example, suppose we have:
25818 template <class T, class U> struct S {};
25819 template <class T> struct S<T*, int> {};
25821 Then, suppose we want to get `S<double*, int>'. SPEC_TMPL will be the
25822 partial specialization and the ARGS will be {double*, int}. The resulting
25823 vector will be {double}, indicating that `T' is bound to `double'. */
25825 static tree
25827 {
25829 tree spec_args
25832 tree deduced_args;
25833 tree innermost_deduced_args;
25837 {
25841 innermost_deduced_args);
25842 }
25843 else
25847 again:
25856 {
25858 {
25864 }
25866 }
25869 {
25872 }
25874 /* Verify that nondeduced template arguments agree with the type
25875 obtained from argument deduction.
25877 For example:
25879 struct A { typedef int X; };
25880 template <class T, class U> struct C {};
25881 template <class T> struct C<T, typename T::X> {};
25883 Then with the instantiation `C<A, int>', we can deduce that
25884 `T' is `A' but unify () does not check whether `typename T::X'
25885 is `int'. */
25896 /* We only need to check the innermost arguments; the other
25897 arguments will always agree. */
25902 /* Now that we have bindings for all of the template arguments,
25903 ensure that the arguments deduced for the template template
25904 parameters have compatible template parameter lists. See the use
25905 of template_template_parm_bindings_ok_p in fn_type_unification
25906 for more information. */
25911 }
25913 // Compare two function templates T1 and T2 by deducing bindings
25914 // from one against the other. If both deductions succeed, compare
25915 // constraints to see which is more constrained.
25916 static int
25918 {
25923 {
25926 }
25929 {
25932 }
25934 // If both deductions succeed, then one may be more constrained.
25939 }
25941 /* TEMPLATES is a TREE_LIST. Each TREE_VALUE is a TEMPLATE_DECL.
25942 Return the TREE_LIST node with the most specialized template, if
25943 any. If there is no most specialized template, the error_mark_node
25944 is returned.
25946 Note that this function does not look at, or modify, the
25947 TREE_PURPOSE or TREE_TYPE of any of the nodes. Since the node
25948 returned is one of the elements of INSTANTIATIONS, callers may
25949 store information in the TREE_PURPOSE or TREE_TYPE of the nodes,
25950 and retrieve it from the value returned. */
25952 tree
25954 {
25961 {
25967 {
25968 /* Equally specialized, move to next function. If there
25969 is no next function, nothing's most specialized. */
25974 }
25975 }
25978 /* Now verify that champ is better than everything earlier in the
25979 instantiation list. */
25982 {
25985 }
25986 }
25988 processing_template_decl--;
25994 }
25996 /* If DECL is a specialization of some template, return the most
25997 general such template. Otherwise, returns NULL_TREE.
25999 For example, given:
26001 template <class T> struct S { template <class U> void f(U); };
26003 if TMPL is `template <class U> void S<int>::f(U)' this will return
26004 the full template. This function will not trace past partial
26005 specializations, however. For example, given in addition:
26007 template <class T> struct S<T*> { template <class U> void f(U); };
26009 if TMPL is `template <class U> void S<int*>::f(U)' this will return
26010 `template <class T> template <class U> S<T*>::f(U)'. */
26012 tree
26014 {
26016 {
26019 /* The TI_TEMPLATE can be an IDENTIFIER_NODE for a
26020 template friend, or a FIELD_DECL for a capture pack. */
26023 }
26028 /* Look for more and more general templates. */
26030 {
26031 /* The DECL_TI_TEMPLATE can be an IDENTIFIER_NODE in some cases.
26032 (See cp-tree.h for details.) */
26041 /* Stop if we run into an explicitly specialized class template. */
26048 }
26051 }
26053 /* Return the most specialized of the template partial specializations
26054 which can produce TARGET, a specialization of some class or variable
26055 template. The value returned is a TEMPLATE_INFO; the TI_TEMPLATE is a
26056 TEMPLATE_DECL node corresponding to the partial specialization, while
26057 the TI_ARGS is the set of template arguments that must be substituted
26058 into the template pattern in order to generate TARGET. The result is
26059 cached in the TI_PARTIAL_INFO of the corresponding TEMPLATE_INFO unless
26060 RECHECKING is true.
26062 If the choice of partial specialization is ambiguous, a diagnostic
26063 is issued, and the error_mark_node is returned. If there are no
26064 partial specializations matching TARGET, then NULL_TREE is
26065 returned, indicating that the primary template should be used. */
26067 tree
26070 {
26074 {
26079 }
26081 {
26085 }
26087 {
26092 }
26093 else
26100 && tinfo
26107 /* There are no partial specializations of this template. */
26113 /* For determining which partial specialization to use, only the
26114 innermost args are interesting. */
26117 {
26120 }
26122 /* The caller hasn't called push_to_top_level yet, but we need
26123 get_partial_spec_bindings to be done in non-template context so that we'll
26124 fully resolve everything. */
26125 processing_template_decl_sentinel ptds;
26129 {
26132 tree spec_tmpl;
26134 {
26135 /* Substitute in the template args from the enclosing class. */
26141 }
26142 else
26147 {
26151 /* Keep the candidate only if its constraints are satisfied. */
26154 }
26155 }
26163 {
26166 ;
26167 else
26168 {
26170 {
26173 {
26176 }
26177 }
26179 }
26180 }
26184 {
26187 {
26190 }
26191 }
26194 {
26201 else
26205 {
26210 }
26213 }
26219 }
26221 /* Explicitly instantiate DECL. */
26223 void
26225 {
26230 /* An error occurred, for which grokdeclarator has already issued
26231 an appropriate message. */
26234 {
26237 }
26239 {
26242 else
26245 }
26251 {
26252 /* There is an asymmetry here in the way VAR_DECLs and
26253 FUNCTION_DECLs are handled by grokdeclarator. In the case of
26254 the latter, the DECL we get back will be marked as a
26255 template instantiation, and the appropriate
26256 DECL_TEMPLATE_INFO will be set up. This does not happen for
26257 VAR_DECLs so we do the lookup here. Probably, grokdeclarator
26258 should handle VAR_DECLs as it currently handles
26259 FUNCTION_DECLs. */
26261 {
26264 }
26267 {
26270 }
26272 {
26277 }
26278 }
26280 {
26283 }
26284 else
26287 /* Check for various error cases. Note that if the explicit
26288 instantiation is valid the RESULT will currently be marked as an
26289 *implicit* instantiation; DECL_EXPLICIT_INSTANTIATION is not set
26290 until we get here. */
26293 {
26294 /* DR 259 [temp.spec].
26296 Both an explicit instantiation and a declaration of an explicit
26297 specialization shall not appear in a program unless the explicit
26298 instantiation follows a declaration of the explicit specialization.
26300 For a given set of template parameters, if an explicit
26301 instantiation of a template appears after a declaration of an
26302 explicit specialization for that template, the explicit
26303 instantiation has no effect. */
26305 }
26307 {
26308 /* [temp.spec]
26310 No program shall explicitly instantiate any template more
26311 than once.
26313 We check DECL_NOT_REALLY_EXTERN so as not to complain when
26314 the first instantiation was `extern' and the second is not,
26315 and EXTERN_P for the opposite case. */
26318 /* If an "extern" explicit instantiation follows an ordinary
26319 explicit instantiation, the template is instantiated. */
26322 }
26324 {
26327 }
26329 {
26332 }
26335 ;
26337 {
26340 "ISO C++ 1998 forbids the use of %<extern%> on explicit "
26343 }
26344 else
26352 }
26354 static void
26356 {
26362 {
26365 }
26366 }
26368 /* Perform an explicit instantiation of template class T. STORAGE, if
26369 non-null, is the RID for extern, inline or static. COMPLAIN is
26370 nonzero if this is called from the parser, zero if called recursively,
26371 since the standard is unclear (as detailed below). */
26373 void
26375 {
26377 {
26381 else
26384 }
26389 {
26392 t);
26394 }
26396 /* At most one of these will be true. */
26402 {
26404 {
26407 "ISO C++ 1998 forbids the use of %<extern%> on "
26409 }
26410 else
26412 "ISO C++ forbids the use of %qE"
26421 else
26423 storage);
26424 }
26427 /* DR 259 [temp.spec].
26429 Both an explicit instantiation and a declaration of an explicit
26430 specialization shall not appear in a program unless the
26431 explicit instantiation follows a declaration of the explicit
26432 specialization.
26434 For a given set of template parameters, if an explicit
26435 instantiation of a template appears after a declaration of an
26436 explicit specialization for that template, the explicit
26437 instantiation has no effect. */
26441 {
26442 /* We've already instantiated the template. */
26444 /* [temp.spec]
26446 No program shall explicitly instantiate any template more
26447 than once.
26449 If EXTERN_P then this is ok. */
26455 }
26463 /* In contrast to implicit instantiation, where only the
26464 declarations, and not the definitions, of members are
26465 instantiated, we have here:
26467 [temp.explicit]
26469 An explicit instantiation that names a class template
26470 specialization is also an explicit instantiation of the same
26471 kind (declaration or definition) of each of its members (not
26472 including members inherited from base classes and members
26473 that are templates) that has not been previously explicitly
26474 specialized in the translation unit containing the explicit
26475 instantiation, provided that the associated constraints, if
26476 any, of that member are satisfied by the template arguments
26477 of the explicit instantiation. */
26481 && !static_p
26485 {
26490 }
26492 {
26498 }
26499 }
26501 /* Given a function DECL, which is a specialization of TMPL, modify
26502 DECL to be a re-instantiation of TMPL with the same template
26503 arguments. TMPL should be the template into which tsubst'ing
26504 should occur for DECL, not the most general template.
26506 One reason for doing this is a scenario like this:
26508 template <class T>
26509 void f(const T&, int i);
26511 void g() { f(3, 7); }
26513 template <class T>
26514 void f(const T& t, const int i) { }
26516 Note that when the template is first instantiated, with
26517 instantiate_template, the resulting DECL will have no name for the
26518 first parameter, and the wrong type for the second. So, when we go
26519 to instantiate the DECL, we regenerate it. */
26521 static void
26523 {
26524 /* The arguments used to instantiate DECL, from the most general
26525 template. */
26528 /* Make sure that we can see identifiers, and compute access correctly. */
26532 {
26533 tree specs;
26537 /* Don't bother with this for unique friends that can't be redeclared and
26538 might change type if regenerated (PR69836). */
26542 /* Use the source location of the definition. */
26550 /* Instantiate a dynamic exception-specification. noexcept will be
26551 handled below. */
26554 {
26560 specs);
26561 }
26563 /* Merge parameter declarations. */
26567 {
26574 }
26577 {
26578 /* If we're regenerating a specialization, the contracts will have
26579 been copied from the most general template. Replace those with
26580 the ones from the actual specialization. */
26583 {
26586 }
26589 }
26591 /* Merge additional specifiers from the CODE_PATTERN. */
26597 }
26599 {
26608 }
26609 else
26612 done:
26614 }
26616 /* Return the TEMPLATE_DECL into which DECL_TI_ARGS(DECL) should be
26617 substituted to get DECL. */
26619 tree
26621 {
26624 /* Set TMPL to the template whose DECL_TEMPLATE_RESULT is the pattern
26625 for the instantiation. This is not always the most general
26626 template. Consider, for example:
26628 template <class T>
26629 struct S { template <class U> void f();
26630 template <> void f<int>(); };
26632 and an instantiation of S<double>::f<int>. We want TD to be the
26633 specialization S<T>::f<int>, not the more general S<T>::f<U>. */
26635 more general template. */
26637 /* We must also deal with friend templates. Given:
26639 template <class T> struct S {
26640 template <class U> friend void f() {};
26641 };
26643 S<int>::f<U> say, is not an instantiation of S<T>::f<U>,
26644 so far as the language is concerned, but that's still
26645 where we get the pattern for the instantiation from. On
26646 other hand, if the definition comes outside the class, say:
26648 template <class T> struct S {
26649 template <class U> friend void f();
26650 };
26651 template <class U> friend void f() {}
26653 we don't need to look any further. That's what the check for
26654 DECL_INITIAL is for. */
26658 {
26659 /* The present template, TD, should not be a definition. If it
26660 were a definition, we should be using it! Note that we
26661 cannot restructure the loop to just keep going until we find
26662 a template with a definition, since that might go too far if
26663 a specialization was declared, but not defined. */
26665 /* Fetch the more general template. */
26667 }
26670 }
26672 /* Returns true if we need to instantiate this template instance even if we
26673 know we aren't going to emit it. */
26675 bool
26677 {
26678 /* We always instantiate inline functions so that we can inline them. An
26679 explicit instantiation declaration prohibits implicit instantiation of
26680 non-inline functions. With high levels of optimization, we would
26681 normally inline non-inline functions -- but we're not allowed to do
26682 that for "extern template" functions. Therefore, we check
26683 DECL_DECLARED_INLINE_P, rather than possibly_inlined_p. */
26687 /* And we need to instantiate static data members so that
26688 their initializers are available in integral constant
26689 expressions. */
26692 }
26694 /* If FN has a noexcept-specifier that hasn't been instantiated yet,
26695 instantiate it now, modifying TREE_TYPE (fn). Returns false on
26696 error, true otherwise. */
26698 bool
26700 {
26704 /* Don't instantiate a noexcept-specification from template context. */
26714 {
26716 /* We're in start_preparsed_function, keep going. */
26723 }
26734 /* For a member friend template we can get a TEMPLATE_DECL. Let's use
26735 its FUNCTION_DECL for the rest of this function -- push_access_scope
26736 doesn't accept TEMPLATE_DECLs. */
26738 {
26741 }
26744 {
26749 }
26751 {
26755 {
26758 /* This might have failed because of an unparsed DMI, so
26759 let's try again later. */
26761 }
26763 {
26764 /* If hash_set::add returns true, the element was already there. */
26769 fn);
26771 }
26773 {
26781 {
26782 /* If needed, set current_class_ptr for the benefit of
26783 tsubst_copy/PARM_DECL. */
26788 }
26790 /* If this function is represented by a TEMPLATE_DECL, then
26791 the deferred noexcept-specification might still contain
26792 dependent types, even after substitution. And we need the
26793 dependency check functions to work in build_noexcept_spec. */
26797 /* Do deferred instantiation of the noexcept-specifier. */
26802 /* Build up the noexcept-specification. */
26812 }
26813 else
26818 }
26821 {
26822 /* This failed with a hard error, so let's go with false. */
26825 }
26832 }
26834 /* We're starting to process the function INST, an instantiation of PATTERN;
26835 add their parameters to local_specializations. */
26837 void
26839 {
26843 {
26847 }
26849 {
26851 {
26854 }
26855 else
26856 {
26857 /* Register the (value) argument pack as a specialization of
26858 TMPL_PARM, then move on. */
26861 }
26862 }
26864 }
26866 /* Instantiate the body of D using PATTERN with ARGS. We have
26867 already determined PATTERN is the correct template to use.
26868 NESTED_P is true if this is a nested function, in which case
26869 PATTERN will be a FUNCTION_DECL not a TEMPLATE_DECL. */
26871 static void
26873 {
26878 {
26881 }
26882 else
26883 /* Only OMP reductions are nested. */
26895 {
26896 /* The variable might be a lambda's extra scope, and that
26897 lambda's visibility depends on D's. */
26900 }
26902 /* Mark D as instantiated so that recursive calls to
26903 instantiate_decl do not try to instantiate it again. */
26907 /* Regenerate the declaration in case the template has been modified
26908 by a subsequent redeclaration. */
26911 /* We already set the file and line above. Reset them now in case
26912 they changed as a result of calling regenerate_decl_from_template. */
26916 {
26917 /* Clear out DECL_RTL; whatever was there before may not be right
26918 since we've reset the type of the declaration. */
26922 /* The initializer is placed in DECL_INITIAL by
26923 regenerate_decl_from_template so we don't need to
26924 push/pop_access_scope again here. Pull it out so that
26925 cp_finish_decl can process it. */
26931 /* Clear DECL_EXTERNAL so that cp_finish_decl will process the
26932 initializer. That function will defer actual emission until
26933 we have a chance to determine linkage. */
26936 /* Enter the scope of D so that access-checking works correctly. */
26946 }
26950 {
26951 /* Set up the list of local specializations. */
26955 /* Set up context. */
26958 else
26959 {
26963 }
26965 /* Create substitution entries for the parameters. */
26968 /* Substitute into the body of the function. */
26972 else
26973 {
26977 /* Set the current input_location to the end of the function
26978 so that finish_function knows where we are. */
26979 input_location
26982 /* Remember if we saw an infinite loop in the template. */
26983 current_function_infinite_loop
26985 }
26987 /* Finish the function. */
26990 else
26991 {
26994 }
26998 }
27000 /* We're not deferring instantiation any more. */
27008 }
27010 /* Produce the definition of D, a _DECL generated from a template. If
27011 DEFER_OK is true, then we don't have to actually do the
27012 instantiation now; we just have to do it sometime. Normally it is
27013 an error if this is an explicit instantiation but D is undefined.
27014 EXPL_INST_CLASS_MEM_P is true iff D is a member of an explicitly
27015 instantiated class template. */
27017 tree
27019 {
27021 tree gen_args;
27022 tree args;
27023 tree td;
27024 tree code_pattern;
27025 tree spec;
27026 tree gen_tmpl;
27032 /* This function should only be used to instantiate templates for
27033 functions and static member variables. */
27036 /* A concept is never instantiated. */
27042 /* We may have a pending instantiation of D itself. */
27045 /* Variables are never deferred; if instantiation is required, they
27046 are instantiated right away. That allows for better code in the
27047 case that an expression refers to the value of the variable --
27048 if the variable has a constant value the referring expression can
27049 take advantage of that fact. */
27053 /* Don't instantiate cloned functions. Instead, instantiate the
27054 functions they cloned. */
27063 /* D has already been instantiated or explicitly specialized, so
27064 there's nothing for us to do here.
27066 It might seem reasonable to check whether or not D is an explicit
27067 instantiation, and, if so, stop here. But when an explicit
27068 instantiation is deferred until the end of the compilation,
27069 DECL_EXPLICIT_INSTANTIATION is set, even though we still need to do
27070 the instantiation. */
27073 /* Check to see whether we know that this template will be
27074 instantiated in some other file, as with "extern template"
27075 extension. */
27078 /* In general, we do not instantiate such templates. */
27085 /* We should already have the extra args. */
27089 /* And what's in the hash table should match D. */
27091 == d
27094 /* This needs to happen before any tsubsting. */
27100 /* Set TD to the template whose DECL_TEMPLATE_RESULT is the pattern
27101 for the instantiation. */
27106 {
27107 /* Look up an explicit specialization, if any. */
27110 {
27113 }
27114 }
27118 /* We should never be trying to instantiate a member of a class
27119 template or partial specialization. */
27124 /* In the case of a friend template whose definition is provided
27125 outside the class, we may have too many arguments. Drop the
27126 ones we don't need. The same is true for specializations. */
27127 args = get_innermost_template_args
27131 {
27137 }
27138 else
27139 {
27143 else
27145 }
27147 /* We may be in the middle of deferred access check. Disable it now. */
27150 /* Unless an explicit instantiation directive has already determined
27151 the linkage of D, remember that a definition is available for
27152 this entity. */
27162 /* If D is a member of an explicitly instantiated class template,
27163 and no definition is available, treat it like an implicit
27164 instantiation. */
27167 {
27168 /* Leave linkage flags alone on instantiations with anonymous
27169 visibility. */
27171 {
27174 }
27176 }
27178 /* Defer all other templates, unless we have been explicitly
27179 forbidden from doing so. */
27181 template. */
27182 ! pattern_defined
27183 /* If it's OK to postpone instantiation, do so. */
27184 || defer_ok
27185 /* If this is a static data member that will be defined
27186 elsewhere, we don't want to instantiate the entire data
27187 member, but we do want to instantiate the initializer so that
27188 we can substitute that elsewhere. */
27190 /* Handle here a deleted function too, avoid generating
27191 its body (c++/61080). */
27193 {
27194 /* The definition of the static data member is now required so
27195 we must substitute the initializer. */
27199 {
27200 tree ns;
27201 tree init;
27210 args,
27212 /* If instantiating the initializer involved instantiating this
27213 again, don't call cp_finish_decl twice. */
27215 {
27216 /* Make sure the initializer is still constant, in case of
27217 circular dependency (template/instantiate6.C). */
27218 const_init
27222 }
27226 }
27228 /* We restore the source position here because it's used by
27229 add_pending_template. */
27235 /* [temp.explicit]
27237 The definition of a non-exported function template, a
27238 non-exported member function template, or a non-exported
27239 member function or static data member of a class template
27240 shall be present in every translation unit in which it is
27241 explicitly instantiated. */
27245 /* If we're in unevaluated context, we just wanted to get the
27246 constant value; this isn't an odr use, so don't queue
27247 a full instantiation. */
27249 /* ??? Historically, we have instantiated inline functions, even
27250 when marked as "extern template". */
27253 }
27254 else
27255 {
27260 }
27267 }
27269 /* Run through the list of templates that we wish we could
27270 instantiate, and instantiate any we can. RETRIES is the
27271 number of times we retry pending template instantiation. */
27273 void
27275 {
27279 /* Instantiating templates may trigger vtable generation. This in turn
27280 may require further template instantiations. We place a limit here
27281 to avoid infinite loop. */
27283 {
27287 "template instantiation depth exceeds maximum of %d"
27288 " instantiating %q+D, possibly from virtual table generation"
27292 /* Pretend that we defined it. */
27295 }
27297 do
27298 {
27303 {
27308 {
27310 {
27325 }
27328 }
27329 else
27330 {
27333 {
27334 instantiation
27340 }
27344 }
27347 {
27348 /* If INSTANTIATION has been instantiated, then we don't
27349 need to consider it again in the future. */
27354 }
27355 else
27356 {
27359 }
27362 }
27364 }
27368 }
27370 /* Substitute ARGVEC into T, which is a list of initializers for
27371 either base class or a non-static data member. The TREE_PURPOSEs
27372 are DECLs, and the TREE_VALUEs are the initializer values. Used by
27373 instantiate_decl. */
27375 static tree
27377 {
27382 {
27383 tree decl;
27384 tree init;
27390 {
27391 tree expr;
27392 tree arg;
27394 /* Expand the base class expansion type into separate base
27395 classes. */
27397 tf_warning_or_error,
27398 NULL_TREE);
27402 /* We'll be building separate TREE_LISTs of arguments for
27403 each base. */
27409 /* Build a dummy EXPR_PACK_EXPANSION that will be used to
27410 expand each argument in the TREE_VALUE of t. */
27417 /* VOID_TYPE_NODE is used to indicate
27418 value-initialization. */
27419 {
27422 }
27423 else
27424 {
27425 /* Substitute parameter packs into each argument in the
27426 TREE_LIST. */
27429 {
27430 tree expanded_exprs;
27432 /* Expand the argument. */
27433 tree value;
27436 else
27437 {
27440 }
27441 expanded_exprs
27443 tf_warning_or_error,
27444 NULL_TREE);
27448 /* Prepend each of the expanded expressions to the
27449 corresponding TREE_LIST in EXPANDED_ARGUMENTS. */
27457 else
27462 }
27465 /* Reverse all of the TREE_LISTs in EXPANDED_ARGUMENTS,
27466 since we built them backwards. */
27468 {
27471 }
27472 }
27473 }
27476 {
27478 {
27482 }
27483 else
27484 {
27485 tree tmp;
27489 else
27503 /* If we had an initializer but it instantiated to nothing,
27504 value-initialize the object. This will only occur when
27505 the initializer was a pack expansion where the parameter
27506 packs used in that expansion were of length zero. */
27509 }
27513 {
27515 decl);
27517 }
27518 /* Look for a target constructor. */
27522 {
27525 {
27529 }
27531 }
27534 {
27536 /* Carry over the dummy TREE_TYPE node containing the source
27537 location. */
27541 }
27542 }
27543 }
27545 }
27547 /* Instantiate an enumerated type. TAG is the template type, NEWTAG
27548 is the instantiation (which should have been created with
27549 start_enum) and ARGS are the template arguments to use. */
27551 static void
27553 {
27554 tree e;
27560 {
27561 tree value;
27564 /* Note that in a template enum, the TREE_VALUE is the
27565 CONST_DECL, not the corresponding INTEGER_CST. */
27569 /* Give this enumeration constant the correct access. */
27572 /* Actually build the enumerator itself. Here we're assuming that
27573 enumerators can't have dependent attributes. */
27577 /* Attribute deprecated without an argument isn't sticky: it'll
27578 melt into a tree flag, so we need to propagate the flag here,
27579 since we just created a new enumerator. */
27582 }
27594 }
27596 /* DECL is a FUNCTION_DECL that is a template specialization. Return
27597 its type -- but without substituting the innermost set of template
27598 arguments. So, innermost set of template parameters will appear in
27599 the type. */
27601 tree
27603 {
27604 /* For a function, DECL_TI_TEMPLATE is partially instantiated. */
27606 }
27608 /* Return truthvalue if we're processing a template different from
27609 the last one involved in diagnostics. */
27610 bool
27612 {
27614 }
27616 /* Remember current template involved in diagnostics. */
27617 void
27619 {
27621 }
27625 {
27627 }
27629 /* Return TRUE if current_function_decl is being instantiated, false
27630 otherwise. */
27632 bool
27634 {
27638 }
27640 /* [temp.param] Check that template non-type parm TYPE is of an allowable
27641 type. Return false for ok, true for disallowed. Issue error and
27642 inform messages under control of COMPLAIN. */
27644 static bool
27646 {
27657 {
27659 {
27664 }
27666 }
27671 /* Fall through; before C++11 alias templates, a bound ttp
27674 /* Any other wildcard type not already handled above is allowed. */
27681 {
27689 {
27690 auto_diagnostic_group d;
27694 }
27696 }
27698 {
27703 }
27706 {
27709 else
27711 type);
27712 }
27714 }
27716 /* Returns true iff the noexcept-specifier for TYPE is value-dependent. */
27718 static bool
27720 {
27723 /* Treat DEFERRED_NOEXCEPT as non-dependent, since it doesn't
27724 affect overload resolution and treating it as dependent breaks
27725 things. Same for an unparsed noexcept expression. */
27732 }
27734 /* Returns TRUE if TYPE is dependent, in the sense of [temp.dep.type].
27735 Assumes that TYPE really is a type, and not the ERROR_MARK_NODE.*/
27737 static bool
27739 {
27740 tree scope;
27742 /* [temp.dep.type]
27744 A type is dependent if it is:
27746 -- a template parameter. Template template parameters are types
27747 for us (since TYPE_P holds true for them) so we handle
27748 them here. */
27752 /* -- a qualified-id with a nested-name-specifier which contains a
27753 class-name that names a dependent type or whose unqualified-id
27754 names a dependent type. */
27758 /* An alias template specialization can be dependent even if the
27759 resulting type is not. */
27763 /* -- a cv-qualified type where the cv-unqualified type is
27764 dependent.
27765 No code is necessary for this bullet; the code below handles
27766 cv-qualified types, and we don't want to strip aliases with
27767 TYPE_MAIN_VARIANT because of DR 1558. */
27768 /* -- a compound type constructed from any dependent type. */
27776 {
27777 tree arg_type;
27782 arg_type;
27788 /* A value-dependent noexcept-specifier makes the type dependent. */
27791 }
27792 /* -- an array type constructed from any dependent type or whose
27793 size is specified by a constant expression that is
27794 value-dependent.
27796 We checked for type- and value-dependence of the bounds in
27797 compute_array_index_type, so TYPE_DEPENDENT_P is already set. */
27799 {
27804 }
27806 /* -- a template-id in which either the template name is a template
27807 parameter ... */
27810 /* ... or any of the template arguments is a dependent type or
27811 an expression that is type-dependent or value-dependent. */
27813 && (any_dependent_template_arguments_p
27817 /* All TYPEOF_TYPEs, DECLTYPE_TYPEs, and TRAIT_TYPEs are
27818 dependent; if the argument of the `typeof' expression is not
27819 type-dependent, then it should already been have resolved. */
27825 /* A template argument pack is dependent if any of its packed
27826 arguments are. */
27828 {
27833 }
27835 /* All TYPE_PACK_EXPANSIONs are dependent, because parameter packs must
27836 be template parameters. */
27846 /* The standard does not specifically mention types that are local
27847 to template functions or local classes, but they should be
27848 considered dependent too. For example:
27850 template <int I> void f() {
27851 enum E { a = I };
27852 S<sizeof (E)> s;
27853 }
27855 The size of `E' cannot be known until the value of `I' has been
27856 determined. Therefore, `E' must be considered dependent. */
27860 /* Don't use type_dependent_expression_p here, as it can lead
27861 to infinite recursion trying to determine whether a lambda
27862 nested in a lambda is dependent (c++/47687). */
27866 && (any_dependent_template_arguments_p
27870 /* Other types are non-dependent. */
27872 }
27874 /* Returns TRUE if TYPE is dependent, in the sense of
27875 [temp.dep.type]. Note that a NULL type is considered dependent. */
27877 bool
27879 {
27880 /* If there are no template parameters in scope, then there can't be
27881 any dependent types. */
27883 {
27884 /* If we are not processing a template, then nobody should be
27885 providing us with a dependent type. */
27889 }
27891 /* If the type is NULL, we have not computed a type for the entity
27892 in question; in that case, the type is dependent. */
27896 /* Erroneous types can be considered non-dependent. */
27900 /* If we have not already computed the appropriate value for TYPE,
27901 do so now. */
27903 {
27906 }
27909 }
27911 /* Returns TRUE if SCOPE is a dependent scope, in which we can't do any
27912 lookup. In other words, a dependent type that is not the current
27913 instantiation. */
27915 bool
27917 {
27920 }
27922 /* True if we might find more declarations in SCOPE during instantiation than
27923 we can when parsing the template. */
27925 bool
27927 {
27929 }
27931 /* T is a SCOPE_REF. Return whether it represents a non-static member of
27932 an unknown base of 'this' (and is therefore instantiation-dependent). */
27934 static bool
27936 {
27953 }
27955 /* T is a SCOPE_REF; return whether we need to consider it
27956 instantiation-dependent so that we can check access at instantiation
27957 time even though we know which member it resolves to. */
27959 static bool
27961 {
27969 else
27971 }
27973 /* Returns TRUE if the EXPRESSION is value-dependent, in the sense of
27974 [temp.dep.constexpr]. EXPRESSION is already known to be a constant
27975 expression. */
27977 /* Note that this predicate is not appropriate for general expressions;
27978 only constant expressions (that satisfy potential_constant_expression)
27979 can be tested for value dependence. */
27981 bool
27983 {
27987 /* A type-dependent expression is also value-dependent. */
27992 {
27994 /* A dependent member function of the current instantiation. */
27998 /* A dependent member function of the current instantiation. */
28005 /* A name that has not been looked up -- must be dependent. */
28009 /* A non-type template parm. */
28013 /* A non-type template parm. */
28019 /* A constant with literal type and is initialized
28020 with an expression that is value-dependent. */
28024 {
28027 /* __PRETTY_FUNCTION__ inside a template function is dependent
28028 on the name of the function. */
28030 /* It might be used in a template, but not a template
28031 function, in which case its DECL_VALUE_EXPR will be
28032 "top level". */
28035 }
28037 /* FIXME cp_finish_decl doesn't fold reference initializers. */
28039 /* We have a constexpr variable and we're processing a template. When
28040 there's lifetime extension involved (for which finish_compound_literal
28041 used to create a temporary), we'll not be able to evaluate the
28042 variable until instantiating, so pretend it's value-dependent. */
28054 /* These expressions are value-dependent if the type to which
28055 the cast occurs is dependent or the expression being casted
28056 is value-dependent. */
28057 {
28063 /* A functional cast has a list of operands. */
28066 {
28067 /* If there are no operands, it must be an expression such
28068 as "int()". This should not happen for aggregate types
28069 because it would form non-constant expressions. */
28074 }
28084 }
28089 /* FALLTHRU */
28092 /* A `sizeof' expression is value-dependent if the operand is
28093 type-dependent or is a pack expansion. */
28102 /* An 'encode' expression is value-dependent if the operand is
28103 type-dependent. */
28112 /* All instantiation-dependent expressions should also be considered
28113 value-dependent. */
28121 /* A NONTYPE_ARGUMENT_PACK is value-dependent if any packed argument
28122 is value-dependent. */
28129 {
28145 }
28156 {
28160 }
28163 /* Treat all requires-expressions as value-dependent so
28164 we don't try to fold them. */
28171 {
28178 {
28180 /* In a call to a constexpr member function, look through the
28181 implicit ADDR_EXPR on the object argument so that it doesn't
28182 cause the call to be considered value-dependent. We also
28183 look through it in potential_constant_expression. */
28190 }
28192 }
28199 {
28201 tree val;
28208 }
28211 /* Treat a GNU statement expression as dependent to avoid crashing
28212 under instantiate_non_dependent_expr; it can't be constant. */
28217 /* The second operand is a type, which type_dependent_expression_p
28218 (and therefore value_dependent_expression_p) doesn't want to see. */
28224 /* A constant expression is value-dependent if any subexpression is
28225 value-dependent. */
28227 {
28234 {
28238 {
28241 /* In some cases, some of the operands may be missing.
28242 (For example, in the case of PREDECREMENT_EXPR, the
28243 amount to increment by may be missing.) That doesn't
28244 make the expression dependent. */
28247 }
28248 }
28252 }
28254 }
28256 /* The expression is not value-dependent. */
28258 }
28260 /* Returns TRUE if the EXPRESSION is type-dependent, in the sense of
28261 [temp.dep.expr]. Note that an expression with no type is
28262 considered dependent. Other parts of the compiler arrange for an
28263 expression with type-dependent subexpressions to have no type, so
28264 this function doesn't have to be fully recursive. */
28266 bool
28268 {
28279 /* An unresolved name is always dependent. */
28285 /* A lambda-expression in template context is dependent. dependent_type_p is
28286 true for a lambda in the scope of a class or function template, but that
28287 doesn't cover all template contexts, like a default template argument. */
28291 /* A fold expression is type-dependent. */
28298 /* Some expression forms are never type-dependent. */
28311 /* The types of these expressions depends only on the type to which
28312 the cast occurs. */
28321 /* The types of these expressions depends only on the type created
28322 by the expression. */
28325 {
28326 /* For NEW_EXPR tree nodes created inside a template, either
28327 the object type itself or a TREE_LIST may appear as the
28328 operand 1. */
28331 /* This is an array type. We need to check array dimensions
28332 as well. */
28334 || value_dependent_expression_p
28336 /* Array type whose dimension has to be deduced. */
28340 else
28342 }
28345 {
28349 /* 14.6.2.2 [temp.dep.expr]: An id-expression is type-dependent if it
28350 contains an identifier associated by name lookup with one or more
28351 declarations declared with a dependent type, or...a
28352 nested-name-specifier or qualified-id that names a member of an
28353 unknown specialization. */
28356 }
28366 {
28371 }
28373 /* A static data member of the current instantiation with incomplete
28374 array type is type-dependent, as the definition and specializations
28375 can have different bounds. */
28382 /* An array of unknown bound depending on a variadic parameter, eg:
28384 template<typename... Args>
28385 void foo (Args... args)
28386 {
28387 int arr[] = { args... };
28388 }
28390 template<int... vals>
28391 void bar ()
28392 {
28393 int arr[] = { vals... };
28394 }
28396 If the array has no length and has an initializer, it must be that
28397 we couldn't determine its length in cp_complete_array_type because
28398 it is dependent. */
28406 /* Pull a FUNCTION_DECL out of a BASELINK if we can. */
28408 {
28413 }
28415 /* A function or variable template-id is type-dependent if it has any
28416 dependent template arguments. */
28420 {
28421 /* Consider the innermost template arguments, since those are the ones
28422 that come from the template-id; the template arguments for the
28423 enclosing class do not make it type-dependent unless they are used in
28424 the type of the decl. */
28426 && (any_dependent_template_arguments_p
28429 }
28431 /* Otherwise, if the function decl isn't from a dependent scope, it can't be
28432 type-dependent. Checking this is important for functions with auto return
28433 type, which looks like a dependent type. */
28442 {
28446 }
28448 /* Otherwise, its constraints could still depend on outer template parameters
28449 from its (dependent) scope. */
28451 /* As an optimization, check this cheaper sufficient condition first.
28452 (At this point we've established that we're looking at a member of
28453 a dependent class, so it makes sense to start treating say undeduced
28454 auto as dependent.) */
28459 /* Always dependent, on the number of arguments if nothing else. */
28464 {
28469 {
28475 }
28476 /* SCOPE_REF with non-null TREE_TYPE is always non-dependent. */
28480 /* CO_AWAIT/YIELD_EXPR with unknown type is always dependent. */
28486 {
28491 }
28494 {
28501 }
28510 }
28512 /* The type of a non-type template parm declared with a placeholder type
28513 depends on the corresponding template argument, even though
28514 placeholders are not normally considered dependent. */
28521 /* Dependent type attributes might not have made it from the decl to
28522 the type yet. */
28528 }
28530 /* [temp.dep.expr]/5: A class member access expression (5.2.5) is
28531 type-dependent if the expression refers to a member of the current
28532 instantiation and the type of the referenced member is dependent, or the
28533 class member access expression refers to a member of an unknown
28534 specialization.
28536 This function returns true if the OBJECT in such a class member access
28537 expression is of an unknown specialization. */
28539 bool
28541 {
28542 /* An IDENTIFIER_NODE can sometimes have a TREE_TYPE, but it's still
28543 dependent. */
28548 }
28550 /* walk_tree callback function for instantiation_dependent_expression_p,
28551 below. Returns non-zero if a dependent subexpression is found. */
28553 static tree
28556 {
28558 {
28559 /* We don't have to worry about decltype currently because decltype
28560 of an instantiation-dependent expr is a dependent type. This
28561 might change depending on the resolution of DR 1172. */
28564 }
28567 {
28568 /* Don't treat an argument list as dependent just because it has no
28569 TREE_TYPE. */
28580 /* We'll check value-dependence separately. */
28583 /* Handle expressions with type operands. */
28588 {
28593 {
28596 else
28597 {
28600 }
28601 }
28603 }
28607 /* In a template, finish_class_member_access_expr creates a
28608 COMPONENT_REF with an IDENTIFIER_NODE for op1 even if it isn't
28609 type-dependent, so that we can check access control at
28610 instantiation time (PR 42277). See also Core issue 1273. */
28617 else
28620 /* Treat statement-expressions as dependent. */
28624 /* Treat requires-expressions as dependent. */
28635 /* Before C++17, a noexcept-specifier isn't part of the function type
28636 so it doesn't affect type dependence, but we still want to consider it
28637 for instantiation dependence. */
28646 }
28650 else
28652 }
28654 /* Returns TRUE if the EXPRESSION is instantiation-dependent, in the
28655 sense defined by the ABI:
28657 "An expression is instantiation-dependent if it is type-dependent
28658 or value-dependent, or it has a subexpression that is type-dependent
28659 or value-dependent."
28661 Except don't actually check value-dependence for unevaluated expressions,
28662 because in sizeof(i) we don't care about the value of i. Checking
28663 type-dependence will in turn check value-dependence of array bounds/template
28664 arguments as needed. */
28666 bool
28668 {
28669 tree result;
28680 }
28682 /* As above, but also check value-dependence of the expression as a whole. */
28684 bool
28686 {
28688 || (processing_template_decl
28691 }
28693 /* Like type_dependent_expression_p, but it also works while not processing
28694 a template definition, i.e. during substitution or mangling. */
28696 bool
28698 {
28704 }
28706 /* Returns TRUE if ARGS contains a type-dependent expression. */
28708 bool
28710 {
28719 }
28721 /* Returns TRUE if LIST (a TREE_LIST whose TREE_VALUEs are
28722 expressions) contains any type-dependent expressions. */
28724 bool
28726 {
28732 }
28734 /* Returns TRUE if LIST (a TREE_LIST whose TREE_VALUEs are
28735 expressions) contains any value-dependent expressions. */
28737 bool
28739 {
28745 }
28747 /* Returns TRUE if the ARG (a template argument) is dependent. */
28749 bool
28751 {
28755 /* Assume a template argument that was wrongly written by the user
28756 is dependent. This is consistent with what
28757 any_dependent_template_arguments_p [that calls this function]
28758 does. */
28768 {
28771 /* A member template of a dependent class is not necessarily
28772 type-dependent, but it is a dependent template argument because it
28773 will be a member of an unknown specialization to that template. */
28776 }
28778 {
28784 }
28787 else
28789 }
28791 /* Identify any expressions that use function parms. */
28793 static tree
28795 {
28798 {
28801 }
28803 }
28805 /* Returns true if a type specialization formed using the template
28806 arguments ARGS needs to use structural equality. */
28808 bool
28810 {
28820 {
28823 {
28829 {
28830 /* Look inside the argument pack. */
28833 }
28836 {
28845 /* An any_targ_node argument (added by add_defaults_to_ttp)
28846 makes the corresponding specialization not canonicalizable,
28847 since template_args_equal always return true for it. We
28848 may see this when called from bind_template_template_parm. */
28850 /* Checking current_function_decl because this structural
28851 comparison is only necessary for redeclaration. */
28854 && (cp_walk_tree_without_duplicates
28856 /* The identity of a class template specialization that uses
28857 a function parameter depends on the identity of the function.
28858 And if this specialization appeared in the trailing return
28859 type thereof, we don't know the identity of the function
28860 (e.g. if it's a redeclaration or a new function) until we
28861 form its signature and go through duplicate_decls. Thus
28862 it's unsafe to decide on a canonical type now (which depends
28863 on the DECL_CONTEXT of the function parameter, which can get
28864 mutated after the fact by duplicate_decls), so just require
28865 structural equality in this case (PR52830). */
28870 /* Require structural equality for specializations written
28871 in terms of a dependent alias template specialization. */
28876 /* Require structural equality for specializations written
28877 in terms of a class template specialization that itself
28878 needs structural equality. */
28880 }
28881 }
28882 }
28885 }
28887 /* Returns true if ARGS (a collection of template arguments) contains
28888 any dependent arguments. */
28890 bool
28892 {
28899 {
28904 }
28907 }
28909 /* Returns true if ARGS contains any errors. */
28911 bool
28913 {
28921 {
28924 else
28926 }
28932 {
28937 }
28940 }
28942 /* Returns TRUE if the template TMPL is type-dependent. */
28944 bool
28946 {
28948 {
28953 }
28955 /* Template template parameters are dependent. */
28959 /* So are names that have not been looked up. */
28963 }
28965 /* Returns TRUE if the specialization TMPL<ARGS> is dependent. */
28967 bool
28969 {
28972 }
28974 /* Returns TRUE if OMP_FOR with DECLV, INITV, CONDV and INCRV vectors
28975 are dependent. */
28977 bool
28979 {
28986 {
29011 {
29015 }
29019 {
29023 {
29029 /* If this loop has a class iterator with != comparison
29030 with increment other than i++/++i/i--/--i, make sure the
29031 increment is constant. */
29034 {
29037 else
29041 }
29042 }
29043 }
29044 }
29047 }
29049 /* TYPE is a TYPENAME_TYPE. Returns the ordinary TYPE to which the
29050 TYPENAME_TYPE corresponds. Returns the original TYPENAME_TYPE if
29051 no such TYPE can be found. Note that this function peers inside
29052 uninstantiated templates and therefore should be used only in
29053 extremely limited situations. ONLY_CURRENT_P restricts this
29054 peering to the currently open classes hierarchy (which is required
29055 when comparing types). */
29057 tree
29059 {
29060 tree scope;
29061 tree name;
29062 tree decl;
29064 tree pushed_scope;
29065 tree result;
29070 /* We shouldn't have built a TYPENAME_TYPE with a non-dependent scope. */
29073 /* Usually the non-qualified identifier of a TYPENAME_TYPE is
29074 TYPE_IDENTIFIER (type). But when 'type' is a typedef variant of a
29075 TYPENAME_TYPE node, then TYPE_NAME (type) is set to the TYPE_DECL
29076 representing the typedef. In that case TYPE_IDENTIFIER (type) is
29077 not the non-qualified identifier of the TYPENAME_TYPE anymore.
29078 So by getting the TYPE_IDENTIFIER of the _main declaration_ of
29079 the TYPENAME_TYPE instead, we avoid messing up with a possible
29080 typedef variant case. */
29083 /* If the SCOPE is itself a TYPENAME_TYPE, then we need to resolve
29084 it first before we can figure out what NAME refers to. */
29086 {
29088 /* Given a class template A with a dependent base with nested type C,
29089 typedef typename A::C::C C will land us here, as trying to resolve
29090 the initial A::C leads to the local C typedef, which leads back to
29091 A::C::C. So we break the recursion now. */
29093 else
29095 }
29096 /* If we don't know what SCOPE refers to, then we cannot resolve the
29097 TYPENAME_TYPE. */
29100 /* If this is a typedef, we don't want to look inside (c++/11987). */
29103 /* If SCOPE isn't the template itself, it will not have a valid
29104 TYPE_FIELDS list. */
29106 /* scope is either the template itself or a compatible instantiation
29107 like X<T>, so look up the name in the original template. */
29109 /* If scope has no fields, it can't be a current instantiation. Check this
29110 before currently_open_class to avoid infinite recursion (71515). */
29113 /* If the SCOPE is not the current instantiation, there's no reason
29114 to look inside it. */
29117 /* Enter the SCOPE so that name lookup will be resolved as if we
29118 were in the class definition. In particular, SCOPE will no
29119 longer be considered a dependent type. */
29121 /* Look up the declaration. */
29123 tf_warning_or_error);
29127 /* For a TYPENAME_TYPE like "typename X::template Y<T>", we want to
29128 find a TEMPLATE_DECL. Otherwise, we want to find a TYPE_DECL. */
29134 {
29138 }
29141 {
29142 /* Obtain the template and the arguments. */
29145 {
29146 /* We get here with a plain identifier because a previous tentative
29147 parse of the nested-name-specifier as part of a ptr-operator saw
29148 ::template X<A>. The use of ::template is necessary in a
29149 ptr-operator, but wrong in a declarator-id.
29151 [temp.names]: In a qualified-id of a declarator-id, the keyword
29152 template shall not appear at the top level. */
29156 }
29158 /* Instantiate the template. */
29164 }
29166 /* Leave the SCOPE. */
29170 /* If we failed to resolve it, return the original typename. */
29174 /* If lookup found a typename type, resolve that too. */
29176 {
29177 /* Ill-formed programs can cause infinite recursion here, so we
29178 must catch that. */
29182 }
29184 /* Qualify the resulting type. */
29190 }
29192 /* Returns a type which represents 'auto' or 'decltype(auto)'. We use a
29193 TEMPLATE_TYPE_PARM with a level one deeper than the actual template parms,
29194 by default. If set_canonical is true, we set TYPE_CANONICAL on it. */
29196 static tree
29198 {
29214 }
29216 tree
29218 {
29220 }
29222 tree
29224 {
29226 }
29228 /* Return a C++17 deduction placeholder for class template TMPL.
29229 There are represented as an 'auto' with the special level 0 and
29230 CLASS_PLACEHOLDER_TEMPLATE set. */
29232 tree
29234 {
29237 /* Our canonical type depends on the placeholder. */
29240 }
29242 /* True iff T is a C++17 class template deduction placeholder. */
29244 bool
29246 {
29248 }
29250 /* Make a "constrained auto" type-specifier. This is an auto or
29251 decltype(auto) type with constraints that must be associated after
29252 deduction. The constraint is formed from the given concept CON
29253 and its optional sequence of template arguments ARGS.
29255 TYPE must be the result of make_auto_type or make_decltype_auto_type. */
29257 static tree
29259 {
29260 /* Build the constraint. */
29272 /* Our canonical type depends on the constraint. */
29275 /* Attach the constraint to the type declaration. */
29277 }
29279 /* Make a "constrained auto" type-specifier. */
29281 tree
29283 {
29286 }
29288 /* Make a "constrained decltype(auto)" type-specifier. */
29290 tree
29292 {
29295 }
29297 /* Returns true if the placeholder type constraint T has any dependent
29298 (explicit) template arguments. */
29300 static bool
29302 {
29307 {
29310 }
29317 }
29319 /* Build and return a concept definition. Like other templates, the
29320 CONCEPT_DECL node is wrapped by a TEMPLATE_DECL. This returns the
29321 the TEMPLATE_DECL. */
29323 tree
29325 {
29331 /* A concept-definition shall not have associated constraints. */
29333 {
29336 }
29338 /* A concept-definition shall appear in namespace scope. Templates
29339 aren't allowed in block scope, so we only need to check for class
29340 scope. */
29342 {
29345 }
29348 {
29351 }
29353 /* Initially build the concept declaration; its type is bool. */
29363 /* Push the enclosing template. */
29365 }
29367 /* Given type ARG, return std::initializer_list<ARG>. */
29369 static tree
29371 {
29376 {
29380 "deducing from brace-enclosed initializer list"
29384 }
29390 }
29392 /* Replace auto in TYPE with std::initializer_list<auto>. */
29394 static tree
29396 {
29403 }
29405 /* Hash traits for hashing possibly constrained 'auto'
29406 TEMPLATE_TYPE_PARMs for use by do_auto_deduction. */
29409 {
29412 };
29414 /* Hash the 'auto' T. */
29416 inline hashval_t
29418 {
29420 /* Matching constrained-type-specifiers denote the same template
29421 parameter, so hash the constraint. */
29423 else
29424 /* But unconstrained autos are all separate, so just hash the pointer. */
29426 }
29428 /* Compare two 'auto's. */
29432 {
29439 /* Two unconstrained autos are distinct. */
29444 }
29446 /* for_each_template_parm callback for extract_autos: if t is a (possibly
29447 constrained) auto, add it to the vector. */
29449 static int
29451 {
29454 {
29455 /* All the autos were built with index 0; fix that up now. */
29459 /* If this is a repeated constrained-type-specifier, use the index we
29460 chose before. */
29462 else
29463 {
29464 /* Otherwise this is new, so use the current count. */
29467 }
29469 {
29474 }
29475 }
29477 /* Always keep walking. */
29479 }
29481 /* Return a TREE_VEC of the 'auto's used in type under the Concepts TS, which
29482 says they can appear anywhere in the type. */
29484 static tree
29486 {
29494 {
29498 }
29501 }
29503 /* The stem for deduction guide names. */
29506 /* Return the name for a deduction guide for class template TMPL. */
29508 tree
29510 {
29521 }
29523 /* True if NAME is the name of a deduction guide. */
29525 bool
29527 {
29531 }
29533 /* True if FN is a deduction guide. */
29535 bool
29537 {
29542 }
29544 /* True if FN is the copy deduction guide, i.e. A(A)->A. */
29546 bool
29548 {
29555 }
29557 /* True if FN is a guide generated from a constructor template. */
29559 bool
29561 {
29569 }
29571 /* True if FN is an aggregate initialization guide or the copy deduction
29572 guide. */
29574 bool
29576 {
29580 /* Explicitly declared. */
29583 /* Derived from a constructor. */
29586 }
29588 /* OLDDECL is a _DECL for a template parameter. Return a similar parameter at
29589 LEVEL:INDEX, using tsubst_args and complain for substitution into non-type
29590 template parameter types. Note that the handling of template template
29591 parameters relies on current_template_parms being set appropriately for the
29592 new template. */
29594 static tree
29597 {
29603 tree newtype;
29606 {
29610 }
29611 else
29612 {
29615 {
29616 // Substitute once to fix references to other template parameters.
29619 // Now substitute again to reduce the level of the auto.
29622 }
29623 else
29626 }
29628 tree newdecl
29633 tree newidx;
29636 {
29645 {
29646 tree newresult
29651 // First create a copy (ttargs) of tsubst_args with an
29652 // additional level for the template template parameter's own
29653 // template parameters (ttparms).
29654 tree ttparms = (INNERMOST_TEMPLATE_PARMS
29662 // Substitute ttargs into ttparms to fix references to
29663 // other template parameters.
29666 // Now substitute again with args based on tparms, to reduce
29667 // the level of the ttparms.
29670 complain);
29671 // Finally, tack the adjusted parms onto tparms.
29674 // As with all template template parms, the parameter list captured
29675 // by this template template parm that corresponds to its own level
29676 // should be empty. This avoids infinite recursion when structurally
29677 // comparing two such rewritten template template parms (PR102479).
29682 // All done.
29686 }
29690 else
29692 }
29693 else
29694 {
29696 tree newconst
29708 }
29711 }
29713 /* As rewrite_template_parm, but for the whole TREE_LIST representing a
29714 template parameter. */
29716 static tree
29719 {
29734 }
29736 /* Returns a C++17 class deduction guide template based on the constructor
29737 CTOR. As a special case, CTOR can be a RECORD_TYPE for an implicit default
29738 guide, REFERENCE_TYPE for an implicit copy/move guide, or TREE_LIST for an
29739 aggregate initialization guide. OUTER_ARGS are the template arguments
29740 for the enclosing scope of the class. */
29742 static tree
29744 {
29748 location_t loc;
29752 {
29756 }
29759 {
29761 {
29765 else
29767 }
29770 else
29780 }
29781 else
29782 {
29788 fn_tmpl
29796 /* If type is a member class template, DECL_TI_ARGS (ctor) will have
29797 fully specialized args for the enclosing class. Strip those off, as
29798 the deduction guide won't have those template parameters. */
29801 /* Discard the 'this' parameter. */
29809 {
29812 /* For a member template constructor, we need to flatten the two
29813 template parameter lists into one, and then adjust the function
29814 signature accordingly. This gets...complicated. */
29817 /* For a member template we should have two levels of parms/args, one
29818 for the class and one for the constructor. We stripped
29819 specialized args for further enclosing classes above. */
29823 /* Template args for translating references to the two-level template
29824 parameters into references to the one-level template parameters we
29825 are creating. */
29830 /* Template parms for the constructor template. */
29833 /* Template parms for the class template. */
29837 /* Template parms for the deduction guide start as a copy of the
29838 template parms for the class. We set current_template_parms for
29839 lookup_template_class_1. */
29845 /* Now we need to rewrite the constructor parms to append them to the
29846 class parms. */
29848 {
29852 tree newelt
29858 }
29860 /* Now we have a final set of template parms to substitute into the
29861 function signature. */
29868 {
29870 /* FIXME: We'd like to avoid substituting outer template
29871 arguments into the constraint ahead of time, but the
29872 construction of tsubst_args assumes that outer arguments
29873 are already substituted in. */
29876 }
29878 /* Parms are to have DECL_CHAIN tsubsted, which would be skipped if
29879 cp_unevaluated_operand. */
29880 cp_evaluated ev;
29883 }
29884 else
29885 {
29886 /* Substitute in the same arguments to rewrite class members into
29887 references to members of an unknown specialization. */
29888 cp_evaluated ev;
29892 {
29894 /* FIXME: As above. */
29897 }
29898 }
29903 }
29906 {
29907 /* Copy the parms so we can set DECL_PRIMARY_TEMPLATE. */
29911 }
29915 FUNCTION_DECL,
29930 }
29932 /* Add to LIST the member types for the reshaped initializer CTOR. */
29934 static tree
29936 {
29940 {
29944 {
29950 }
29954 /* Give the trailing pack expansion parameter a default argument to
29955 match aggregate initialization behavior, even if we deduce the
29956 length of the pack separately to more than we have initializers. */
29958 /* if ei is of array type and xi is a braced-init-list or string literal,
29959 Ti is an rvalue reference to the declared type of ei */
29964 {
29966 ftype = cp_build_qualified_type
29968 ftype = (cp_build_reference_type
29970 }
29972 }
29975 }
29977 /* Return whether ETYPE is, or is derived from, a specialization of TMPL. */
29979 static bool
29981 {
29987 tree tparms = (INNERMOST_TEMPLATE_PARMS
29994 }
29996 /* Return a C++20 aggregate deduction candidate for TYPE initialized from
29997 INIT. */
29999 static tree
30001 {
30009 {
30015 }
30017 /* We might be creating a guide for a class member template, e.g.,
30019 template<typename U> struct A {
30020 template<typename T> struct B { T t; };
30021 };
30023 At this point, A will have been instantiated. Below, we need to
30024 use both A<U>::B<T> (TEMPLATE_TYPE) and A<int>::B<T> (TYPE) types. */
30025 const bool member_template_p
30029 tree template_type = (member_template_p
30035 /* No aggregate candidate for copy-initialization. */
30037 {
30041 }
30043 /* If we encounter a problem, we just won't add the candidate. */
30048 {
30053 /* If we're creating a deduction guide for a member class template,
30054 we've used the original template pattern type for the reshape_init
30055 above; this is done because we want PARMS to be a template parameter
30056 type, something that can be deduced when used as a function template
30057 parameter. At this point the outer class template has already been
30058 partially instantiated (we deferred the deduction until the enclosing
30059 scope is non-dependent). Therefore we have to partially instantiate
30060 PARMS, so that its template level is properly reduced and we don't get
30061 mismatches when deducing types using the guide with PARMS. */
30063 {
30067 }
30068 }
30070 {
30073 len;
30075 {
30081 }
30082 }
30083 else
30084 /* Aggregate initialization doesn't apply to an initializer expression. */
30088 {
30094 }
30097 }
30099 /* UGUIDES are the deduction guides for the underlying template of alias
30100 template TMPL; adjust them to be deduction guides for TMPL.
30102 This routine also handles C++23 inherited CTAD, in which case TMPL is a
30103 TREE_LIST representing a synthetic alias template whose TREE_PURPOSE is
30104 the template parameter list of the alias template (equivalently, of the
30105 derived class) and TREE_VALUE the defining-type-id (equivalently, the
30106 base whose guides we're inheriting). UGUIDES are the base's guides. */
30108 static tree
30110 {
30111 /* [over.match.class.deduct]: When resolving a placeholder for a deduced
30112 class type (9.2.8.2) where the template-name names an alias template A,
30113 the defining-type-id of A must be of the form
30115 typename(opt) nested-name-specifier(opt) template(opt) simple-template-id
30117 as specified in 9.2.8.2. The guides of A are the set of functions or
30118 function templates formed as follows. For each function or function
30119 template f in the guides of the template named by the simple-template-id
30120 of the defining-type-id, the template arguments of the return type of f
30121 are deduced from the defining-type-id of A according to the process in
30122 13.10.2.5 with the exception that deduction does not fail if not all
30123 template arguments are deduced. Let g denote the result of substituting
30124 these deductions into f. If substitution succeeds, form a function or
30125 function template f' with the following properties and add it to the set
30126 of guides of A:
30128 * The function type of f' is the function type of g.
30130 * If f is a function template, f' is a function template whose template
30131 parameter list consists of all the template parameters of A (including
30132 their default template arguments) that appear in the above deductions or
30133 (recursively) in their default template arguments, followed by the
30134 template parameters of f that were not deduced (including their default
30135 template arguments), otherwise f' is not a function template.
30137 * The associated constraints (13.5.2) are the conjunction of the
30138 associated constraints of g and a constraint that is satisfied if and only
30139 if the arguments of A are deducible (see below) from the return type.
30141 * If f is a copy deduction candidate (12.4.1.8), then f' is considered to
30142 be so as well.
30144 * If f was generated from a deduction-guide (12.4.1.8), then f' is
30145 considered to be so as well.
30147 * The explicit-specifier of f' is the explicit-specifier of g (if
30148 any). */
30153 {
30158 }
30159 else
30160 {
30165 }
30172 {
30179 {
30183 /* Deduce template arguments for f from the type-id of A. */
30189 /* CWG2664: Discard any deductions, still build the guide. */
30193 /* The number of parms for f' is the number of parms of A used in
30194 the deduced arguments plus non-deduced parms of f. */
30206 /* Set current_template_parms as in build_deduction_guide. */
30214 /* First copy over the used parms of A. */
30217 {
30220 {
30225 }
30226 }
30229 /* Adjust the deduced template args for f to refer to the A parms
30230 with their new indexes. */
30234 /* Now rewrite the non-deduced parms of f. */
30237 {
30244 }
30247 /* Substitute the deduced arguments plus the rewritten template
30248 parameters into f to get g. This covers the type, copyness,
30249 guideness, and explicit-specifier. */
30250 tree g;
30251 {
30252 /* Parms are to have DECL_CHAIN tsubsted, which would be skipped
30253 if cp_unevaluated_operand. */
30254 cp_evaluated ev;
30257 }
30261 {
30262 /* The targs are all non-dependent, so g isn't a template. */
30266 }
30275 /* Substitute the associated constraints. */
30282 /* Add a constraint that the return type matches the instantiation of
30283 A with the same template arguments. */
30287 /* FIXME this should mean they don't compare as equivalent. */
30289 {
30292 }
30295 {
30298 }
30299 }
30300 else
30301 {
30302 /* For a non-template deduction guide, if the arguments of A aren't
30303 deducible from the return type, don't add the candidate. */
30304 non_template:
30308 }
30310 /* Rewrite the return type of the inherited guide in terms of the
30311 derived class. This is specified as replacing the return type R
30312 with typename CC<R>::type where the partially specialized CC maps a
30313 base class specialization to a specialization of the derived class
30314 having such a base (inducing substitution failure if no such derived
30315 class exists).
30317 As specified this mapping would be done at instantiation time using
30318 non-dependent template arguments, but we do it ahead of time using
30319 the generic arguments. This seems to be good enough since generic
30320 deduction should succeed only if concrete deduction would. */
30322 {
30340 }
30343 }
30346 }
30348 /* CTOR is a using-decl inheriting the constructors of some base of the class
30349 template TMPL; adjust the base's guides be deduction guides for TMPL. */
30351 static tree
30353 {
30354 /* [over.match.class.deduct]: In addition, if C is defined and inherits
30355 constructors ([namespace.udecl]) from a direct base class denoted in the
30356 base-specifier-list by a class-or-decltype B, let A be an alias template
30357 whose template parameter list is that of C and whose defining-type-id is
30358 B. If A is a deducible template ([dcl.type.simple]), the set contains the
30359 guides of A with the return type R of each guide replaced with typename
30360 CC::type given a class template
30362 template <typename> class CC;
30364 whose primary template is not defined and with a single partial
30365 specialization whose template parameter list is that of A and whose
30366 template argument list is a specialization of A with the template argument
30367 list of A ([temp.dep.type]) having a member typedef type designating a
30368 template specialization with the template argument list of A but with C as
30369 the template. */
30371 /* FIXME: Also recognize inherited constructors of the form 'using C::B::B',
30372 which seem to be represented with TYPENAME_TYPE C::B as USING_DECL_SCOPE?
30373 And recognize constructors inherited from a non-dependent base class, which
30374 seem to be missing from the overload set entirely? */
30386 }
30388 /* If template arguments for TMPL can be deduced from TYPE, return
30389 the deduced arguments, otherwise return NULL_TREE.
30390 Used to implement CPTK_IS_DEDUCIBLE for alias CTAD according to
30391 [over.match.class.deduct].
30393 This check is specified in terms of partial specialization, so the behavior
30394 should be parallel to that of get_partial_spec_bindings. */
30396 tree
30398 {
30401 {
30402 /* If tmpl is a class template, this is trivial: it's deducible if
30403 TYPE is a specialization of TMPL. */
30405 {
30410 else
30412 }
30414 /* Otherwise it's an alias template. */
30417 }
30418 else
30419 {
30420 /* TMPL is a synthetic alias template represented as a TREE_LIST as
30421 per alias_ctad_tweaks. */
30425 }
30431 again:
30436 /* We don't fail on an undeduced targ the second time through (like
30437 get_partial_spec_bindings) because we're going to try defaults. */
30440 {
30446 {
30451 }
30452 /* If the type parameter is a parameter pack, then it will be deduced
30453 to an empty parameter pack. This is another case that doesn't model
30454 well as partial specialization. */
30456 {
30457 tree arg;
30459 {
30462 }
30463 else
30467 }
30468 }
30470 /* Maybe add in default template args. This seems like a flaw in the
30471 specification in terms of partial specialization, since it says the
30472 partial specialization has the the template parameter list of A, but a
30473 partial specialization can't have default targs. */
30478 /* I believe we don't need the template_template_parm_bindings_ok_p call
30479 because coerce_template_parms did coerce_template_template_parms. */
30485 }
30487 /* Return artificial deduction guides built from the constructors of class
30488 template TMPL. */
30490 static tree
30492 {
30499 {
30500 /* We handle C++23 inherited CTAD below. */
30506 }
30511 {
30515 }
30517 /* Add implicit default constructor deduction guide. */
30519 {
30521 complain);
30523 }
30525 /* Add copy guide. */
30526 {
30529 complain);
30531 }
30534 }
30538 /* Return the non-aggregate deduction guides for deducible template TMPL. The
30539 aggregate candidate is added separately because it depends on the
30540 initializer. Set ANY_DGUIDES_P if we find a non-implicit deduction
30541 guide. */
30543 static tree
30545 {
30548 {
30552 complain);
30553 }
30554 else
30555 {
30561 else
30563 }
30565 /* Cache the deduction guides for a template. We also remember the result of
30566 lookup, and rebuild everything if it changes; should be very rare. */
30567 /* FIXME: Also rebuild if this is a class template that inherits guides from a
30568 base class, and lookup for the latter changed. */
30572 {
30576 }
30577 else
30578 {
30581 }
30586 else
30587 {
30591 }
30595 }
30597 /* Return whether TMPL is a (class template argument-) deducible template. */
30599 bool
30601 {
30602 /* A deducible template is either a class template or is an alias template
30603 whose defining-type-id is of the form
30605 typename(opt) nested-name-specifier(opt) template(opt) simple-template-id
30607 where the nested-name-specifier (if any) is non-dependent and the
30608 template-name of the simple-template-id names a deducible template. */
30619 }
30621 /* Deduce template arguments for the class template placeholder PTYPE for
30622 template TMPL based on the initializer INIT, and return the resulting
30623 type. */
30625 static tree
30628 {
30629 /* We should have handled this in the caller. */
30633 /* If the class was erroneous, don't try to deduce, because that
30634 can generate a lot of diagnostic. */
30640 /* Wait until the enclosing scope is non-dependent. */
30645 /* Initializing one placeholder from another. */
30656 {
30660 }
30662 {
30664 {
30665 /* Be permissive with equivalent alias templates. */
30668 bool complained
30670 "alias template deduction only available "
30675 {
30678 }
30679 }
30680 else
30682 }
30684 /* Wait until the initializer is non-dependent. */
30688 /* Don't bother with the alias rules for an equivalent template. */
30701 {
30706 {
30707 /* As an exception, the first phase in 16.3.1.7 (considering the
30708 initializer list as a single argument) is omitted if the
30709 initializer list consists of a single expression of type cv U,
30710 where U is a specialization of C or a class derived from a
30711 specialization of C. */
30715 }
30718 else
30720 }
30723 else
30726 /* Do this now to avoid problems with erroneous args later on. */
30736 /* Prune explicit deduction guides in copy-initialization context (but
30737 not copy-list-initialization). */
30740 {
30746 {
30747 /* Found a nonconverting guide, prune the candidates. */
30754 }
30755 }
30763 /* If this is list-initialization and the class has a list guide, first
30764 try deducing from the list as a single argument, as [over.match.list]. */
30766 {
30774 {
30775 /* That didn't work, now try treating the list as a sequence of
30776 arguments. */
30782 }
30783 }
30786 {
30788 " of %qT, as it has no non-explicit deduction guides or "
30791 }
30793 {
30797 }
30803 {
30805 {
30811 }
30813 }
30814 /* [over.match.list]/1: In copy-list-initialization, if an explicit
30815 constructor is chosen, the initialization is ill-formed. */
30817 {
30819 {
30821 {
30822 // TODO: Pass down location from cp_finish_decl.
30824 "explicit deduction guide selected in "
30829 }
30831 }
30832 }
30834 /* If CTAD succeeded but the type doesn't have any explicit deduction
30835 guides, this deduction might not be what the user intended. */
30837 {
30841 "%qT may not intend to support class template argument "
30845 }
30849 }
30851 /* Return true if INIT is an unparenthesized id-expression or an
30852 unparenthesized class member access. Used for the argument of
30853 decltype(auto). */
30855 bool
30857 {
30860 /* We need to be able to tell '(r)' and 'r' apart (when it's of
30861 reference type). Only the latter is an id-expression. */
30869 }
30871 /* Replace occurrences of 'auto' in TYPE with the appropriate type deduced
30872 from INIT. AUTO_NODE is the TEMPLATE_TYPE_PARM used for 'auto' in TYPE.
30873 The CONTEXT determines the context in which auto deduction is performed
30874 and is used to control error diagnostics. FLAGS are the LOOKUP_* flags.
30876 OUTER_TARGS is used during template argument deduction (context == adc_unify)
30877 to properly substitute the result. It's also used in the adc_unify and
30878 adc_requirement contexts to communicate the necessary template arguments
30879 to satisfaction. OUTER_TARGS is ignored in other contexts.
30881 Additionally for adc_unify contexts TMPL is the template for which TYPE
30882 is a template parameter type.
30884 For partial-concept-ids, extra args from OUTER_TARGS, TMPL and the current
30885 scope may be appended to the list of deduced template arguments prior to
30886 determining constraint satisfaction as appropriate. */
30888 tree
30895 {
30901 /* Defining a subset of type-dependent expressions that we can deduce
30902 from ahead of time isn't worth the trouble. */
30905 /* Similarly, we can't deduce from another undeduced decl. */
30909 /* We may be doing a partial substitution, but we still want to replace
30910 auto_node. */
30914 {
30915 /* We don't recurse here because we can't deduce from a nested
30916 initializer_list. */
30920 }
30924 /* In C++23, we must deduce the type to int&& for code like
30925 decltype(auto) f(int&& x) { return (x); }
30926 or
30927 auto&& f(int x) { return x; }
30928 so we use treat_lvalue_as_rvalue_p. But don't do it for
30929 decltype(auto) f(int x) { return x; }
30930 where we should deduce 'int' rather than 'int&&'; transmogrifying
30931 INIT to an rvalue would break that. */
30932 tree r;
30942 /* C++17 class template argument deduction. */
30946 /* Nothing we can do with this, even in deduction context. */
30951 /* [dcl.spec.auto]: Obtain P from T by replacing the occurrences of auto
30952 with either a new invented type template parameter U or, if the
30953 initializer is a braced-init-list (8.5.4), with
30954 std::initializer_list<U>. */
30956 {
30961 else
30962 {
30964 {
30968 "for deduction to %<std::initializer_list%>, use copy-"
30970 }
30972 }
30973 }
30978 tree targs;
30982 {
30983 /* [dcl.struct.bind]/1 - if decomposition declaration has no ref-qualifiers
30984 and initializer has array type, deduce cv-qualified array type. */
30987 }
30989 {
30997 }
30998 else
30999 {
31004 tree tparms;
31008 else
31009 {
31013 }
31017 DEDUCE_CALL,
31020 {
31022 /* Try again at instantiation time. */
31026 /* If type is error_mark_node a diagnostic must have been
31027 emitted by now. Also, having a mention to '<type error>'
31028 in the diagnostic is not really useful to the user. */
31029 {
31032 && (auto_node
31036 init);
31037 else
31040 DEDUCE_CALL,
31042 }
31044 }
31045 }
31047 /* Check any placeholder constraints against the deduced type. */
31051 {
31053 {
31058 /* If the constraint is dependent, we need to wait until
31059 instantiation time to resolve the placeholder. */
31062 }
31069 {
31073 {
31074 /* As in satisfy_declaration_constraints. */
31078 else
31080 }
31081 }
31088 /* HACK: Compensate for callers not always communicating all levels of
31089 outer template arguments by filling in the outermost missing levels
31090 with dummy levels before checking satisfaction. We'll still crash
31091 if the constraint depends on a template argument belonging to one of
31092 these missing levels, but this hack otherwise allows us to handle a
31093 large subset of possible constraints (including all non-dependent
31094 constraints). */
31097 {
31102 }
31105 {
31107 {
31108 auto_diagnostic_group d;
31110 {
31128 }
31130 }
31132 }
31133 }
31136 /* The outer template arguments are already substituted into type
31143 }
31145 /* Substitutes LATE_RETURN_TYPE for 'auto' in TYPE and returns the
31146 result. */
31148 tree
31150 {
31152 {
31155 }
31159 {
31160 /* In an abbreviated function template we didn't know we were dealing
31161 with a function template when we saw the auto return type, so rebuild
31162 the return type using an auto with the correct level. */
31167 auto_vec);
31168 /* Also rebuild the constraint info in terms of the new auto. */
31176 }
31178 }
31180 /* Returns true iff TYPE is a TEMPLATE_TYPE_PARM representing 'auto' or
31181 'decltype(auto)' or a deduced class template. */
31183 bool
31185 {
31190 else
31192 }
31194 /* for_each_template_parm callback for type_uses_auto. */
31196 int
31198 {
31200 }
31202 /* Returns the TEMPLATE_TYPE_PARM in TYPE representing `auto' iff TYPE contains
31203 a use of `auto'. Returns NULL_TREE otherwise. */
31205 tree
31207 {
31211 /* For parameter packs, check the contents of the pack. */
31216 {
31217 /* The Concepts TS allows multiple autos in one type-specifier; just
31218 return the first one we find, do_auto_deduction will collect all of
31219 them. */
31223 else
31225 }
31226 else
31228 }
31230 /* Report ill-formed occurrences of auto types in ARGUMENTS. If
31231 concepts are enabled, auto is acceptable in template arguments, but
31232 only when TEMPL identifies a template class. Return TRUE if any
31233 such errors were reported. */
31235 bool
31237 {
31239 /* Only the concepts TS allows 'auto' as a type-id; it'd otherwise
31240 have already been rejected by the parser more generally. */
31243 /* If there were previous errors, nevermind. */
31247 /* If TMPL is an identifier, we're parsing and we can't tell yet
31248 whether TMPL is supposed to be a type, a function or a variable.
31249 We'll only be able to tell during template substitution, so we
31250 expect to be called again then. If concepts are enabled and we
31251 know we have a type, we're ok. */
31258 /* Quickly search for any occurrences of auto; usually there won't
31259 be any, and then we'll avoid allocating the vector. */
31267 {
31272 }
31275 }
31277 /* Recursively walk over && expressions searching for EXPR. Return a reference
31278 to that expression. */
31281 {
31285 {
31290 }
31292 }
31294 /* Convert the generic type parameters in PARM that match the types given in the
31295 range [START_IDX, END_IDX) from the current_template_parms into generic type
31296 packs. */
31298 tree
31300 {
31311 {
31312 /* Create a distinct parameter pack type from the current parm and add it
31313 to the replacement args to tsubst below into the generic function
31314 parameter. */
31328 /* Replace the current template parameter with new pack. */
31331 /* Surgically adjust the associated constraint of adjusted parameter
31332 and it's corresponding contribution to the current template
31333 requirements. */
31335 {
31338 /* Use UNKNOWN_LOCATION so write_template_args can tell the
31339 difference between this and a fold the user wrote. */
31342 TRUTH_ANDIF_EXPR);
31345 /* If there was a constraint, we also need to replace that in
31346 the template requirements, which we've already built. */
31350 }
31351 }
31357 /* If there are more levels then build up the replacement with the outer
31358 template parms. */
31362 replacement);
31365 }
31367 /* __integer_pack(N) in a pack expansion expands to a sequence of numbers from
31368 0..N-1. */
31370 void
31372 {
31375 integer_type_node,
31376 NULL_TREE),
31380 CP_BUILT_IN_INTEGER_PACK);
31381 }
31383 /* Walk the decl or type specialization table calling FN on each
31384 entry. */
31386 void
31390 {
31396 }
31398 /* Lookup the specialization of *ELT, in the decl or type
31399 specialization table. Return the SPEC that's already there, or
31400 NULL if nothing. */
31402 tree
31404 {
31414 }
31416 /* Return flags encoding whether SPEC is on the instantiation and/or
31417 specialization lists of TMPL. */
31419 unsigned
31421 {
31427 {
31430 }
31435 /* Only need to search if DECL is a partial specialization. */
31439 {
31442 }
31445 }
31447 /* Add a new specialization described by SPEC. DECL is the
31448 maybe-template decl and FLAGS is as returned from
31449 get_mergeable_specialization_flags. */
31451 void
31454 {
31457 {
31466 {
31469 }
31470 }
31473 {
31476 /* We don't distinguish different constrained partial type
31477 specializations, so there could be duplicates. Everything else
31478 must be new. */
31480 {
31486 }
31487 }
31494 {
31495 /* A partial specialization. */
31500 }
31501 }
31503 /* Set up the hash tables for template instantiations. */
31505 void
31507 {
31513 }
31515 /* Print stats about the template hash tables for -fstats. */
31517 void
31519 {
31528 }
31530 #if CHECKING_P
31534 /* Verify that type_dependent_expression_p () works correctly, even
31535 in the presence of location wrapper nodes. */
31537 static void
31539 {
31544 /* If no templates are involved, nothing is type-dependent. */
31550 /* Within a template, an unresolved name is always type-dependent. */
31553 /* Ensure it copes with NULL_TREE and errors. */
31557 /* A USING_DECL in a template should be type-dependent, even if wrapped
31558 with a location wrapper (PR c++/83799). */
31567 }
31569 /* Run all of the selftests within this file. */
31571 void
31573 {
31575 }