| blob | 68ce4a87372945243e4d9b0149161a16379687c3 |
1 /* Handle parameterized types (templates) for GNU -*- C++ -*-.
2 Copyright (C) 1992-2023 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. */
51 /* The type of functions taking a tree, and some additional data, and
52 returning an int. */
55 /* The PENDING_TEMPLATES is a list of templates whose instantiations
56 have been deferred, either because their definitions were not yet
57 available, or because we were putting off doing the work. */
59 {
62 };
76 /* Live only within one (recursive) call to tsubst_expr. We use
77 this to pass the statement expression node from the STMT_EXPR
78 to the EXPR_STMT that is its result. */
81 // -------------------------------------------------------------------------- //
82 // Local Specialization Stack
83 //
84 // Implementation of the RAII helper for creating new local
85 // specializations.
88 {
90 ;
93 else
95 }
98 {
100 {
103 }
104 }
106 /* True if we've recursed into fn_type_unification too many times. */
110 {
114 };
116 /* The general template is not in these tables. */
121 /* Contains canonical template parameter types. The vector is indexed by
122 the TEMPLATE_TYPE_IDX of the template parameter. Each element is a
123 TREE_LIST, whose TREE_VALUEs contain the canonical template
124 parameters of various types and levels. */
127 #define UNIFY_ALLOW_NONE 0
128 #define UNIFY_ALLOW_MORE_CV_QUAL 1
129 #define UNIFY_ALLOW_LESS_CV_QUAL 2
130 #define UNIFY_ALLOW_DERIVED 4
131 #define UNIFY_ALLOW_INTEGER 8
132 #define UNIFY_ALLOW_OUTER_LEVEL 16
133 #define UNIFY_ALLOW_OUTER_MORE_CV_QUAL 32
134 #define UNIFY_ALLOW_OUTER_LESS_CV_QUAL 64
137 tbr_incomplete_type,
138 tbr_ambiguous_baseclass,
139 tbr_success
140 };
227 /* Make the current scope suitable for access checking when we are
228 processing T. T can be FUNCTION_DECL for instantiated function
229 template, VAR_DECL for static member variable, or TYPE_DECL for
230 for a class or alias template (needed by instantiate_decl). */
232 void
234 {
246 /* An artificial deduction guide should have the same access as
247 the constructor. */
249 else
253 {
256 }
257 }
259 /* Restore the scope set up by push_access_scope. T is the node we
260 are processing. */
262 void
264 {
274 else
276 }
278 /* Do any processing required when DECL (a member template
279 declaration) is finished. Returns the TEMPLATE_DECL corresponding
280 to DECL, unless it is a specialization, in which case the DECL
281 itself is returned. */
283 tree
285 {
292 {
293 tree type;
301 {
305 }
307 }
312 {
314 {
317 }
318 else
320 }
321 else
326 }
328 /* Create a template info node. */
330 tree
332 {
337 }
339 /* Return the template info node corresponding to T, whatever T is. */
341 tree
343 {
365 }
367 /* Returns the template nesting level of the indicated class TYPE.
369 For example, in:
370 template <class T>
371 struct A
372 {
373 template <class U>
374 struct B {};
375 };
377 A<T>::B<U> has depth two, while A<T> has depth one.
378 Both A<T>::B<int> and A<int>::B<U> have depth one, if
379 they are instantiations, not specializations.
381 This function is guaranteed to return 0 if passed NULL_TREE so
382 that, for example, `template_class_depth (current_class_type)' is
383 always safe. */
385 int
387 {
391 {
401 {
404 else
406 }
409 else
411 }
414 }
416 /* Return TRUE if NODE instantiates a template that has arguments of
417 its own, be it directly a primary template or indirectly through a
418 partial specializations. */
419 static bool
421 {
433 /* So now we know we have a specialization, but it could be a full
434 or a partial specialization. To tell which, compare the depth of
435 its template arguments with those of its context. */
444 }
446 /* Subroutine of maybe_begin_member_template_processing.
447 Returns true if processing DECL needs us to push template parms. */
449 static bool
451 {
457 }
459 /* Subroutine of maybe_begin_member_template_processing.
460 Push the template parms in PARMS, starting from LEVELS steps into the
461 chain, and ending at the beginning, since template parms are listed
462 innermost first. */
464 static void
466 {
474 current_template_parms
482 NULL);
484 {
493 {
500 /* Push the CONST_DECL. */
506 }
507 }
508 }
510 /* Restore the template parameter context for a member template, a
511 friend template defined in a class definition, or a non-template
512 member of template class. */
514 void
516 {
517 tree parms;
522 {
525 /* Disregard full specializations (c++/60999). */
528 }
531 {
536 {
539 }
542 }
544 /* Remember how many levels of template parameters we pushed so that
545 we can pop them later. */
547 }
549 /* Undo the effects of maybe_begin_member_template_processing. */
551 void
553 {
562 {
566 }
567 }
569 /* Return a new template argument vector which contains all of ARGS,
570 but has as its innermost set of arguments the EXTRA_ARGS. */
572 tree
574 {
575 tree new_args;
593 }
595 /* Like add_to_template_args, but only the outermost ARGS are added to
596 the EXTRA_ARGS. In particular, all but TMPL_ARGS_DEPTH
597 (EXTRA_ARGS) levels are added. This function is used to combine
598 the template arguments from a partial instantiation with the
599 template arguments used to attain the full instantiation from the
600 partial instantiation.
602 If ARGS is a TEMPLATE_DECL, use its parameters as args. */
604 tree
606 {
607 tree new_args;
612 {
615 }
617 /* If there are more levels of EXTRA_ARGS than there are ARGS,
618 something very fishy is going on. */
621 /* If *all* the new arguments will be the EXTRA_ARGS, just return
622 them. */
626 /* For the moment, we make ARGS look like it contains fewer levels. */
631 /* Now, we restore ARGS to its full dimensions. */
635 }
637 /* Return the N levels of innermost template arguments from the ARGS. */
639 tree
641 {
642 tree new_args;
648 /* If N is 1, just return the innermost set of template arguments. */
652 /* If we're not removing anything, just return the arguments we were
653 given. */
659 /* Make a new set of arguments, not containing the outer arguments. */
666 }
668 /* The inverse of get_innermost_template_args: Return all but the innermost
669 EXTRA_LEVELS levels of template arguments from the ARGS. */
671 static tree
673 {
674 tree new_args;
680 /* If N is 1, just return the outermost set of template arguments. */
684 /* If we're not removing anything, just return the arguments we were
685 given. */
690 /* Make a new set of arguments, not containing the inner arguments. */
697 }
699 /* We've got a template header coming up; push to a new level for storing
700 the parms. */
702 void
704 {
705 /* We use a non-tag-transparent scope here, which causes pushtag to
706 put tags in this scope, rather than in the enclosing class or
707 namespace scope. This is the right thing, since we want
708 TEMPLATE_DECLS, and not TYPE_DECLS for template classes. For a
709 global template class, push_template_decl handles putting the
710 TEMPLATE_DECL into top-level scope. For a nested template class,
711 e.g.:
713 template <class T> struct S1 {
714 template <class T> struct S2 {};
715 };
717 pushtag contains special code to insert the TEMPLATE_DECL for S2
718 at the right scope. */
724 /* Add a dummy parameter level while we process the parameter list. */
725 current_template_parms
728 current_template_parms);
729 }
731 /* This routine is called when a specialization is declared. If it is
732 invalid to declare a specialization here, an error is reported and
733 false is returned, otherwise this routine will return true. */
735 static bool
737 {
740 /* [temp.expl.spec]
742 An explicit specialization shall be declared in the namespace of
743 which the template is a member, or, for member templates, in the
744 namespace of which the enclosing class or enclosing class
745 template is a member. An explicit specialization of a member
746 function, member class or static data member of a class template
747 shall be declared in the namespace of which the class template
748 is a member. */
750 {
753 }
755 /* [temp.expl.spec]
757 In an explicit specialization declaration for a member of a class
758 template or a member template that appears in namespace scope,
759 the member template and some of its enclosing class templates may
760 remain unspecialized, except that the declaration shall not
761 explicitly specialize a class member template if its enclosing
762 class templates are not explicitly specialized as well. */
764 {
767 }
770 }
772 /* We've just seen template <>. */
774 bool
776 {
780 }
782 /* Called at then end of processing a declaration preceded by
783 template<>. */
785 void
787 {
790 }
792 /* Any template <>'s that we have seen thus far are not referring to a
793 function specialization. */
795 void
797 {
800 }
802 /* We've just seen a template header. If SPECIALIZATION is nonzero,
803 it was of the form template <>. */
805 static void
807 {
809 template_header_count++;
810 }
812 /* We're beginning an explicit instantiation. */
814 void
816 {
819 }
822 void
824 {
827 }
829 /* An explicit specialization or partial specialization of TMPL is being
830 declared. Check that the namespace in which the specialization is
831 occurring is permissible. Returns false iff it is invalid to
832 specialize TMPL in the current namespace. */
834 static bool
836 {
839 /* [tmpl.expl.spec]
841 An explicit specialization shall be declared in a namespace enclosing the
842 specialized template. An explicit specialization whose declarator-id is
843 not qualified shall be declared in the nearest enclosing namespace of the
844 template, or, if the namespace is inline (7.3.1), any namespace from its
845 enclosing namespace set. */
848 {
851 }
854 /* Same or enclosing namespace. */
856 else
857 {
858 auto_diagnostic_group d;
864 }
865 }
867 /* SPEC is an explicit instantiation. Check that it is valid to
868 perform this explicit instantiation in the current namespace. */
870 static void
872 {
873 tree ns;
875 /* DR 275: An explicit instantiation shall appear in an enclosing
876 namespace of its template. */
882 }
884 /* Returns true if TYPE is a new partial specialization that needs to be
885 set up. This may also modify TYPE to point to the correct (new or
886 existing) constrained partial specialization. */
888 static bool
890 {
891 /* An implicit instantiation of an incomplete type implies
892 the definition of a new class template.
894 template<typename T>
895 struct S;
897 template<typename T>
898 struct S<T*>;
900 Here, S<T*> is an implicit instantiation of S whose type
901 is incomplete. */
905 /* It can also be the case that TYPE is a completed specialization.
906 Continuing the previous example, suppose we also declare:
908 template<typename T>
909 requires Integral<T>
910 struct S<T*>;
912 Here, S<T*> refers to the specialization S<T*> defined
913 above. However, we need to differentiate definitions because
914 we intend to define a new partial specialization. In this case,
915 we rely on the fact that the constraints are different for
916 this declaration than that above.
918 Note that we also get here for injected class names and
919 late-parsed template definitions. We must ensure that we
920 do not create new type declarations for those cases. */
922 {
926 /* If there are no template parameters, this cannot be a new
927 partial template specialization? */
931 /* The injected-class-name is not a new partial specialization. */
935 /* If the constraints are not the same as those of the primary
936 then, we can probably create a new specialization. */
940 {
944 }
946 /* Also, if there's a pre-existing specialization with matching
947 constraints, then this also isn't new. */
950 {
956 {
959 }
961 }
963 /* Create a new type node (and corresponding type decl)
964 for the newly declared specialization. */
969 /* We only need a separate type node for storing the definition of this
970 partial specialization; uses of S<T*> are unconstrained, so all are
971 equivalent. So keep TYPE_CANONICAL the same. */
974 /* Build the corresponding type decl. */
986 }
989 }
991 /* The TYPE is being declared. If it is a template type, that means it
992 is a partial specialization. Do appropriate error-checking. */
994 tree
996 {
997 tree context;
1002 /* A lambda that appears in specialization context is not itself a
1003 specialization. */
1007 /* An injected-class-name is not a specialization. */
1012 {
1016 }
1021 {
1027 else
1030 }
1032 {
1033 /* This is for ordinary explicit specialization and partial
1034 specialization of a template class such as:
1036 template <> class C<int>;
1038 or:
1040 template <class T> class C<T*>;
1042 Make sure that `C<int>' and `C<T*>' are implicit instantiations. */
1045 {
1052 {
1057 }
1058 }
1064 /* Trying to define a specialization either without a template<> header
1065 or in an inappropriate place. We've already given an error, so just
1066 bail now so we don't actually define the specialization. */
1068 }
1074 {
1075 /* This is for an explicit specialization of member class
1076 template according to [temp.expl.spec/18]:
1078 template <> template <class U> class C<int>::D;
1080 The context `C<int>' must be an implicit instantiation.
1081 Otherwise this is just a member class template declared
1082 earlier like:
1084 template <> class C<int> { template <class U> class D; };
1085 template <> template <class U> class C<int>::D;
1087 In the first case, `C<int>::D' is a specialization of `C<T>::D'
1088 while in the second case, `C<int>::D' is a primary template
1089 and `C<T>::D' may not exist. */
1093 {
1094 tree t;
1099 {
1102 type))
1105 }
1107 /* Check for invalid specialization after instantiation:
1109 template <> template <> class C<int>::D<int>;
1110 template <> template <class U> class C<int>::D; */
1114 {
1118 {
1119 /* We already have a full specialization of this partial
1120 instantiation, or a full specialization has been
1121 looked up but not instantiated. Reassign it to the
1122 new member specialization template. */
1123 spec_entry elt;
1136 spec_entry **slot
1141 }
1142 else
1143 /* But if we've had an implicit instantiation, that's a
1144 problem ([temp.expl.spec]/6). */
1147 }
1149 /* Mark TYPE as a specialization. And as a result, we only
1150 have one level of template argument for the innermost
1151 class template. */
1156 }
1157 }
1159 {
1160 /* Someday C++0x may allow for enum template specialization. */
1165 else
1166 {
1169 }
1170 }
1173 }
1175 /* Make sure ARGS doesn't use any inappropriate typedefs; we should have
1176 gone through coerce_template_parms by now. */
1178 static void
1180 {
1182 {
1191 /* Allow typedefs on the type of a non-type argument, since a
1193 else
1195 }
1196 }
1198 static void
1200 {
1205 }
1207 /* Retrieve the specialization (in the sense of [temp.spec] - a
1208 specialization is either an instantiation or an explicit
1209 specialization) of TMPL for the given template ARGS. If there is
1210 no such specialization, return NULL_TREE. The ARGS are a vector of
1211 arguments, or a vector of vectors of arguments, in the case of
1212 templates with more than one level of parameters.
1214 If TMPL is a type template and CLASS_SPECIALIZATIONS_P is true,
1215 then we search for a partial specialization matching ARGS. This
1216 parameter is ignored if TMPL is not a class template.
1218 We can also look up a FIELD_DECL, if it is a lambda capture pack; the
1219 result is a NONTYPE_ARGUMENT_PACK. */
1221 static tree
1223 {
1233 /* There should be as many levels of arguments as there are
1234 levels of parameters. */
1243 /* Lambda functions in templates aren't instantiated normally, but through
1244 tsubst_lambda_expr. */
1248 spec_entry elt;
1256 else
1265 }
1267 /* Like retrieve_specialization, but for local declarations. */
1269 tree
1271 {
1277 }
1279 /* Returns nonzero iff DECL is a specialization of TMPL. */
1281 int
1283 {
1284 tree t;
1287 {
1293 }
1294 else
1295 {
1304 }
1307 }
1309 /* Returns nonzero iff DECL is a specialization of friend declaration
1310 FRIEND_DECL according to [temp.friend]. */
1312 bool
1314 {
1321 /* For [temp.friend/6] when FRIEND_DECL is an ordinary member function
1322 of a template class, we want to check if DECL is a specialization
1323 if this. */
1328 {
1329 /* We want a TEMPLATE_DECL for `is_specialization_of'. */
1332 }
1337 /* There is nothing to do if this is not a template friend. */
1344 /* [temp.friend/6]
1345 A member of a class template may be declared to be a friend of a
1346 non-template class. In this case, the corresponding member of
1347 every specialization of the class template is a friend of the
1348 class granting friendship.
1350 For example, given a template friend declaration
1352 template <class T> friend void A<T>::f();
1354 the member function below is considered a friend
1356 template <> struct A<int> {
1357 void f();
1358 };
1360 For this type of template friend, TEMPLATE_DEPTH below will be
1361 nonzero. To determine if DECL is a friend of FRIEND, we first
1362 check if the enclosing class is a specialization of another. */
1369 {
1370 /* Next, we check the members themselves. In order to handle
1371 a few tricky cases, such as when FRIEND_DECL's are
1373 template <class T> friend void A<T>::g(T t);
1374 template <class T> template <T t> friend void A<T>::h();
1376 and DECL's are
1378 void A<int>::g(int);
1379 template <int> void A<int>::h();
1381 we need to figure out ARGS, the template arguments from
1382 the context of DECL. This is required for template substitution
1383 of `T' in the function parameter of `g' and template parameter
1384 of `h' in the above examples. Here ARGS corresponds to `int'. */
1391 {
1393 {
1396 else
1398 current_depth++;
1399 }
1401 }
1404 {
1406 tree friend_type;
1407 tree decl_type;
1408 tree friend_args_type;
1409 tree decl_args_type;
1411 /* Make sure that both DECL and FRIEND_DECL are templates or
1412 non-templates. */
1418 {
1419 /* If both are templates, check template parameter list. */
1420 tree friend_parms
1425 friend_parms))
1429 }
1430 else
1438 /* Check if return types match. */
1442 /* Check if function parameter types match, ignoring the
1443 `this' parameter. */
1452 }
1453 else
1454 {
1455 /* DECL is a TYPE_DECL */
1459 /* Make sure that both DECL and FRIEND_DECL are templates or
1460 non-templates. */
1461 is_template
1468 {
1469 tree friend_parms;
1470 /* If both are templates, check the name of the two
1471 TEMPLATE_DECL's first because is_friend didn't. */
1476 /* Now check template parameter list. */
1477 friend_parms
1480 return comp_template_parms
1482 friend_parms);
1483 }
1484 else
1487 }
1488 }
1490 }
1492 /* Register the specialization SPEC as a specialization of TMPL with
1493 the indicated ARGS. IS_FRIEND indicates whether the specialization
1494 is actually just a friend declaration. ATTRLIST is the list of
1495 attributes that the specialization is declared with or NULL when
1496 it isn't. Returns SPEC, or an equivalent prior declaration, if
1497 available.
1499 We also store instantiations of field packs in the hash table, even
1500 though they are not themselves templates, to make lookup easier. */
1502 static tree
1504 hashval_t hash)
1505 {
1506 tree fn;
1512 spec_entry elt;
1523 else
1526 /* We can sometimes try to re-register a specialization that we've
1527 already got. In particular, regenerate_decl_from_template calls
1528 duplicate_decls which will update the specialization list. But,
1529 we'll still get called again here anyhow. It's more convenient
1530 to simply allow this than to try to prevent it. */
1534 {
1536 {
1539 {
1541 fn);
1543 }
1544 else
1545 {
1546 tree clone;
1547 /* This situation should occur only if the first
1548 specialization is an implicit instantiation, the
1549 second is an explicit specialization, and the
1550 implicit instantiation has not yet been used. That
1551 situation can occur if we have implicitly
1552 instantiated a member function and then specialized
1553 it later.
1555 We can also wind up here if a friend declaration that
1556 looked like an instantiation turns out to be a
1557 specialization:
1559 template <class T> void foo(T);
1560 class S { friend void foo<>(int) };
1561 template <> void foo(int);
1563 We transform the existing DECL in place so that any
1564 pointers to it become pointers to the updated
1565 declaration.
1567 If there was a definition for the template, but not
1568 for the specialization, we want this to look as if
1569 there were no definition, and vice versa. */
1573 /* The call to duplicate_decls will have applied
1574 [temp.expl.spec]:
1576 An explicit specialization of a function template
1577 is inline only if it is explicitly declared to be,
1578 and independently of whether its function template
1579 is.
1581 to the primary function; now copy the inline bits to
1582 the various clones. */
1584 {
1591 }
1595 }
1596 }
1598 {
1601 /* We've already complained in duplicate_decls. */
1605 /* Dup decl failed, but this is a new definition. Set the
1606 line number so any errors match this new
1607 definition. */
1611 }
1612 }
1616 /* A specialization must be declared in the same namespace as the
1617 template it is specializing. */
1630 /* If TMPL is a forward declaration of a template function, keep a list
1631 of all specializations in case we need to reassign them to a friend
1632 template later in tsubst_friend_function.
1634 Also keep a list of all variable template instantiations so that
1635 process_partial_specialization can check whether a later partial
1636 specialization would have used it. */
1641 }
1643 /* Restricts tree and type comparisons. */
1647 /* Returns true iff two spec_entry nodes are equivalent. */
1649 bool
1651 {
1660 /* tmpl could be a FIELD_DECL for a capture pack. */
1664 {
1665 /* Partial specializations of a variable template can be distinguished by
1666 constraints. */
1670 }
1676 }
1678 /* Returns a hash for a template TMPL and template arguments ARGS. */
1680 static hashval_t
1682 {
1685 }
1687 hashval_t
1689 {
1694 }
1696 /* Returns a hash for a spec_entry node based on the TMPL and ARGS members,
1697 ignoring SPEC. */
1699 hashval_t
1701 {
1703 }
1705 /* Recursively calculate a hash value for a template argument ARG, for use
1706 in the hash tables of template specializations. We must be
1707 careful to (at least) skip the same entities template_args_equal
1708 does. */
1710 hashval_t
1712 {
1717 /* Strip nop-like things, but not the same as STRIP_NOPS. */
1728 {
1730 /* Getting here with an ARGUMENT_PACK_SELECT means we're probably
1731 preserving it in a hash table, which is bad because it will change
1732 meaning when gen_elem_of_pack_expansion_instantiation changes the
1733 ARGUMENT_PACK_SELECT_INDEX. */
1767 {
1770 {
1773 }
1775 }
1779 {
1782 }
1793 val = iterative_hash_template_arg
1805 val);
1807 val);
1816 /* [temp.over.link] Two lambda-expressions are never considered
1817 equivalent.
1819 So just hash the closure type. */
1830 /* Now hash operands as usual. */
1834 {
1837 {
1841 }
1843 call_expr_arg_iterator ai;
1848 }
1852 }
1856 {
1859 {
1860 // We want an alias specialization that survived strip_typedefs
1861 // to hash differently from its TYPE_CANONICAL, to avoid hash
1862 // collisions that compare as different in template_args_equal.
1863 // These could be dependent specializations that strip_typedefs
1864 // left alone, or untouched specializations because
1865 // coerce_template_parms returns the unconverted template
1866 // arguments if it sees incomplete argument packs.
1869 }
1872 {
1879 {
1880 /* Hash the components that are relevant to TYPENAME_TYPE
1881 equivalence as determined by structural_comptypes. We
1882 can only coherently do this when comparing_specializations
1883 is set, because otherwise structural_comptypes tries
1884 resolving TYPENAME_TYPE via the current instantiation. */
1889 }
1896 }
1909 }
1910 }
1912 /* Unregister the specialization SPEC as a specialization of TMPL.
1913 Replace it with NEW_SPEC, if NEW_SPEC is non-NULL. Returns true
1914 if the SPEC was listed as a specialization of TMPL.
1916 Note that SPEC has been ggc_freed, so we can't look inside it. */
1918 bool
1920 {
1922 spec_entry elt;
1930 {
1935 }
1938 }
1940 /* Like register_specialization, but for local declarations. We are
1941 registering SPEC, an instantiation of TMPL. */
1943 void
1945 {
1948 }
1950 /* Registers T as a specialization of itself. This is used to preserve
1951 the references to already-parsed parameters when instantiating
1952 postconditions. */
1954 void
1956 {
1958 }
1960 /* TYPE is a class type. Returns true if TYPE is an explicitly
1961 specialized class. */
1963 bool
1965 {
1969 }
1971 /* Print the list of functions at FNS, going through all the overloads
1972 for each element of the list. Alternatively, FNS cannot be a
1973 TREE_LIST, in which case it will be printed together with all the
1974 overloads.
1976 MORE and *STR should respectively be FALSE and NULL when the function
1977 is called from the outside. They are used internally on recursive
1978 calls. print_candidates manages the two parameters and leaves NULL
1979 in *STR when it ends. */
1981 static void
1983 {
1987 else
1989 {
1995 {
1998 else
2001 }
2003 }
2004 }
2006 /* Print the list of candidate FNS in an error message. FNS can also
2007 be a TREE_LIST of non-functions in the case of an ambiguous lookup. */
2009 void
2011 {
2015 }
2017 /* Get a (possibly) constrained template declaration for the
2018 purpose of ordering candidates. */
2019 static tree
2021 {
2027 }
2029 /* Among candidates having the same signature, return the
2030 most constrained or NULL_TREE if there is no best candidate.
2031 If the signatures of candidates vary (e.g., template
2032 specialization vs. member function), then there can be no
2033 most constrained.
2035 Note that we don't compare constraints on the functions
2036 themselves, but rather those of their templates. */
2037 static tree
2039 {
2040 // Try to find the best candidate in a first pass.
2043 {
2050 }
2052 // Verify that the champ is better than previous candidates.
2057 }
2060 }
2063 /* Returns the template (one of the functions given by TEMPLATE_ID)
2064 which can be specialized to match the indicated DECL with the
2065 explicit template args given in TEMPLATE_ID. The DECL may be
2066 NULL_TREE if none is available. In that case, the functions in
2067 TEMPLATE_ID are non-members.
2069 If NEED_MEMBER_TEMPLATE is nonzero the function is known to be a
2070 specialization of a member template.
2072 The TEMPLATE_COUNT is the number of references to qualifying
2073 template classes that appeared in the name of the function. See
2074 check_explicit_specialization for a more accurate description.
2076 TSK indicates what kind of template declaration (if any) is being
2077 declared. TSK_TEMPLATE indicates that the declaration given by
2078 DECL, though a FUNCTION_DECL, has template parameters, and is
2079 therefore a template function.
2081 The template args (those explicitly specified and those deduced)
2082 are output in a newly created vector *TARGS_OUT.
2084 If it is impossible to determine the result, an error message is
2085 issued. The error_mark_node is returned to indicate failure. */
2087 static tree
2089 tree decl,
2093 tmpl_spec_kind tsk)
2094 {
2095 tree fns;
2096 tree targs;
2097 tree explicit_targs;
2100 /* A TREE_LIST of templates of which DECL may be a specialization.
2101 The TREE_VALUE of each node is a TEMPLATE_DECL. The
2102 corresponding TREE_PURPOSE is the set of template arguments that,
2103 when used to instantiate the template, would produce a function
2104 with the signature of DECL. */
2114 /* We shouldn't be specializing a member template of an
2115 unspecialized class template; we already gave an error in
2116 check_specialization_scope, now avoid crashing. */
2120 {
2123 }
2131 /* Check for baselinks. */
2136 {
2140 }
2142 {
2145 }
2147 /* Count the number of template headers specified for this
2148 specialization. */
2159 {
2162 tf_warning_or_error);
2166 }
2168 {
2172 {
2173 tree decl_arg_types;
2174 tree fn_arg_types;
2176 /* In case of explicit specialization, we need to check if
2177 the number of template headers appearing in the specialization
2178 is correct. This is usually done in check_explicit_specialization,
2179 but the check done there cannot be exhaustive when specializing
2180 member functions. Consider the following code:
2182 template <> void A<int>::f(int);
2183 template <> template <> void A<int>::f(int);
2185 Assuming that A<int> is not itself an explicit specialization
2186 already, the first line specializes "f" which is a non-template
2187 member function, whilst the second line specializes "f" which
2188 is a template member function. So both lines are syntactically
2189 correct, and check_explicit_specialization does not reject
2190 them.
2192 Here, we can do better, as we are matching the specialization
2193 against the declarations. We count the number of template
2194 headers, and we check if they match TEMPLATE_COUNT + 1
2195 (TEMPLATE_COUNT is the number of qualifying template classes,
2196 plus there must be another header for the member template
2197 itself).
2199 Notice that if header_count is zero, this is not a
2200 specialization but rather a template instantiation, so there
2201 is no check we can perform here. */
2203 {
2206 }
2208 /* Check that the number of template arguments at the
2209 innermost level for DECL is the same as for FN. */
2217 /* DECL might be a specialization of FN. */
2221 /* For a non-static member function, we need to make sure
2222 that the const qualification is the same. Since
2223 get_bindings does not try to merge the "this" parameter,
2224 we must do the comparison explicitly. */
2226 {
2231 /* And the ref-qualification. */
2235 }
2237 /* Skip the "this" parameter and, for constructors of
2238 classes with virtual bases, the VTT parameter. A
2239 full specialization of a constructor will have a VTT
2240 parameter, but a template never will. */
2241 decl_arg_types
2243 fn_arg_types
2246 /* Function templates cannot be specializations; there are
2247 no partial specializations of functions. Therefore, if
2248 the type of DECL does not match FN, there is no
2249 match.
2251 Note that it should never be the case that we have both
2252 candidates added here, and for regular member functions
2253 below. */
2255 {
2257 current_template_parms))
2270 {
2271 /* C++20 CA104: Substitute directly into the
2272 constraint-expression. */
2278 }
2282 }
2284 /* See whether this function might be a specialization of this
2285 template. Suppress access control because we might be trying
2286 to make this specialization a friend, and we have already done
2287 access control for the declaration of the specialization. */
2293 /* We cannot deduce template arguments that when used to
2294 specialize TMPL will produce DECL. */
2298 /* We deduced something involving 'auto', which isn't a valid
2299 template argument. */
2302 /* Save this template, and the arguments deduced. */
2304 }
2306 /* FN is an ordinary member function, and we need a
2307 specialization of a member template. */
2308 ;
2310 /* We can get IDENTIFIER_NODEs here in certain erroneous
2311 cases. */
2312 ;
2314 /* This is just an ordinary non-member function. Nothing can
2315 be a specialization of that. */
2316 ;
2318 /* Cannot specialize functions that are created implicitly. */
2319 ;
2320 else
2321 {
2322 tree decl_arg_types;
2324 /* This is an ordinary member function. However, since
2325 we're here, we can assume its enclosing class is a
2326 template class. For example,
2328 template <typename T> struct S { void f(); };
2329 template <> void S<int>::f() {}
2331 Here, S<int>::f is a non-template, but S<int> is a
2332 template class. If FN has the same type as DECL, we
2333 might be in business. */
2336 /* Its enclosing class is an explicit specialization
2337 of a template class. This is not a candidate. */
2342 /* The return types differ. */
2345 /* Adjust the type of DECL in case FN is a static member. */
2352 decl_arg_types))
2360 // If the deduced arguments do not satisfy the constraints,
2361 // this is not a candidate.
2365 // Add the candidate.
2367 }
2368 }
2371 {
2372 /* We have:
2374 [temp.expl.spec]
2376 It is possible for a specialization with a given function
2377 signature to be instantiated from more than one function
2378 template. In such cases, explicit specification of the
2379 template arguments must be used to uniquely identify the
2380 function template specialization being specialized.
2382 Note that here, there's no suggestion that we're supposed to
2383 determine which of the candidate templates is most
2384 specialized. However, we, also have:
2386 [temp.func.order]
2388 Partial ordering of overloaded function template
2389 declarations is used in the following contexts to select
2390 the function template to which a function template
2391 specialization refers:
2393 -- when an explicit specialization refers to a function
2394 template.
2396 So, we do use the partial ordering rules, at least for now.
2397 This extension can only serve to make invalid programs valid,
2398 so it's safe. And, there is strong anecdotal evidence that
2399 the committee intended the partial ordering rules to apply;
2400 the EDG front end has that behavior, and John Spicer claims
2401 that the committee simply forgot to delete the wording in
2402 [temp.expl.spec]. */
2405 {
2408 }
2409 }
2411 // Concepts allows multiple declarations of member functions
2412 // with the same signature. Like above, we need to rely on
2413 // on the partial ordering of those candidates to determine which
2414 // is the best.
2416 {
2418 {
2421 }
2422 }
2425 {
2430 "saw %d %<template<>%>, need %d for "
2435 }
2439 {
2445 }
2447 /* We have one, and exactly one, match. */
2449 {
2453 /* Propagate the candidate's constraints to the declaration. */
2457 /* DECL is a re-declaration or partial instantiation of a template
2458 function. */
2461 /* It was a specialization of an ordinary member function in a
2462 template class. */
2464 }
2466 /* It was a specialization of a template. */
2470 /* Propagate the template's constraints to the declaration. */
2475 }
2477 /* Returns a chain of parameter types, exactly like the SPEC_TYPES,
2478 but with the default argument values filled in from those in the
2479 TMPL_TYPES. */
2481 static tree
2483 tree tmpl_types)
2484 {
2485 tree new_spec_types;
2493 /* Substitute into the rest of the list. */
2494 new_spec_types =
2498 /* Add the default argument for this parameter. */
2501 new_spec_types);
2502 }
2504 /* DECL is an explicit specialization. Replicate default arguments
2505 from the template it specializes. (That way, code like:
2507 template <class T> void f(T = 3);
2508 template <> void f(double);
2509 void g () { f (); }
2511 works, as required.) An alternative approach would be to look up
2512 the correct default arguments at the call-site, but this approach
2513 is consistent with how implicit instantiations are handled. */
2515 static void
2517 {
2518 tree tmpl;
2519 tree spec_types;
2520 tree tmpl_types;
2521 tree new_spec_types;
2522 tree old_type;
2523 tree new_type;
2524 tree t;
2529 /* See if there's anything we need to do. */
2542 {
2543 /* Remove the this pointer, but remember the object's type for
2544 CV quals. */
2550 {
2551 /* DECL may contain more parameters than TMPL due to the extra
2552 in-charge parameter in constructors and destructors. */
2555 }
2557 {
2560 }
2561 }
2563 /* Compute the merged default arguments. */
2564 new_spec_types =
2567 /* Compute the new FUNCTION_TYPE. */
2569 {
2573 new_spec_types);
2576 /* Put the in-charge parameter back. */
2579 new_spec_types);
2583 new_spec_types);
2584 }
2585 else
2587 new_spec_types);
2593 }
2595 /* Return the number of template headers we expect to see for a definition
2596 or specialization of CTYPE or one of its non-template members. */
2598 int
2600 {
2604 {
2605 /* You're supposed to have one `template <...>' for every
2606 template class, but you don't need one for a full
2607 specialization. For example:
2609 template <class T> struct S{};
2610 template <> struct S<int> { void f(); };
2611 void S<int>::f () {}
2613 is correct; there shouldn't be a `template <>' for the
2614 definition of `S<int>::f'. */
2616 /* If CTYPE does not have template information of any
2617 kind, then it is not a template, nor is it nested
2618 within a template. */
2626 }
2629 }
2631 /* Do a simple sanity check on the template headers that precede the
2632 variable declaration DECL. */
2634 void
2636 {
2641 {
2644 "variable templates only available with "
2647 // Namespace-scope variable templates should have a template header.
2649 }
2651 {
2652 auto_diagnostic_group d;
2654 "too many template headers for %qD "
2660 "members of an explicitly specialized class are defined "
2662 }
2663 }
2665 /* An explicit specialization whose declarator-id or class-head-name is not
2666 qualified shall be declared in the nearest enclosing namespace of the
2667 template, or, if the namespace is inline (7.3.1), any namespace from its
2668 enclosing namespace set.
2670 If the name declared in the explicit instantiation is an unqualified name,
2671 the explicit instantiation shall appear in the namespace where its template
2672 is declared or, if that namespace is inline (7.3.1), any namespace from its
2673 enclosing namespace set. */
2675 void
2677 {
2682 {
2688 /* This was allowed in C++98, so only pedwarn. */
2690 "outside its namespace must use a nested-name-"
2692 }
2693 }
2695 /* Warn for a template specialization SPEC that is missing some of a set
2696 of function or type attributes that the template TEMPL is declared with.
2697 ATTRLIST is a list of additional attributes that SPEC should be taken
2698 to ultimately be declared with. */
2700 static void
2702 {
2706 /* Avoid warning if the difference between the primary and
2707 the specialization is not in one of the attributes below. */
2711 };
2713 /* Put together a list of the black listed attributes that the primary
2714 template is declared with that the specialization is not, in case
2715 it's not apparent from the most recent declaration of the primary. */
2716 pretty_printer str;
2723 auto_diagnostic_group d;
2726 spec))
2732 }
2734 /* Check to see if the function just declared, as indicated in
2735 DECLARATOR, and in DECL, is a specialization of a function
2736 template. We may also discover that the declaration is an explicit
2737 instantiation at this point.
2739 Returns DECL, or an equivalent declaration that should be used
2740 instead if all goes well. Issues an error message if something is
2741 amiss. Returns error_mark_node if the error is not easily
2742 recoverable.
2744 FLAGS is a bitmask consisting of the following flags:
2746 2: The function has a definition.
2747 4: The function is a friend.
2749 The TEMPLATE_COUNT is the number of references to qualifying
2750 template classes that appeared in the name of the function. For
2751 example, in
2753 template <class T> struct S { void f(); };
2754 void S<int>::f();
2756 the TEMPLATE_COUNT would be 1. However, explicitly specialized
2757 classes are not counted in the TEMPLATE_COUNT, so that in
2759 template <class T> struct S {};
2760 template <> struct S<int> { void f(); }
2761 template <> void S<int>::f();
2763 the TEMPLATE_COUNT would be 0. (Note that this declaration is
2764 invalid; there should be no template <>.)
2766 If the function is a specialization, it is marked as such via
2767 DECL_TEMPLATE_SPECIALIZATION. Furthermore, its DECL_TEMPLATE_INFO
2768 is set up correctly, and it is added to the list of specializations
2769 for that template. */
2771 tree
2773 tree decl,
2776 tree attrlist)
2777 {
2786 tmpl_spec_kind tsk;
2789 {
2792 else
2794 }
2795 else
2799 {
2802 {
2805 }
2809 {
2811 /* This could be something like:
2813 template <class T> void f(T);
2814 class S { friend void f<>(int); } */
2816 else
2817 {
2818 /* This case handles bogus declarations like template <>
2819 template <class T> void f<int>(); */
2823 declarator);
2825 }
2826 }
2830 /* The error has already been reported in
2831 check_specialization_scope. */
2837 /* Fall through. */
2850 decl);
2853 else
2857 /* Fall through. */
2863 /* In cases like template<> constexpr bool v = true;
2864 We'll give an error in check_template_variable. */
2870 else
2876 {
2877 /* This case handles bogus declarations like template <>
2878 template <class T> void f<int>(); */
2883 declarator);
2885 {
2886 /* Partial specialization of variable template. */
2890 }
2893 "non-type partial specialization %qE "
2895 else
2897 "non-class, non-variable partial specialization %qE "
2900 ok:;
2901 }
2904 /* This is a specialization of a member template, without
2905 specialization the containing class. Something like:
2907 template <class T> struct S {
2908 template <class U> void f (U);
2909 };
2910 template <> template <class U> void S<int>::f(U) {}
2912 That's a specialization -- but of the entire template. */
2918 }
2921 /* This doesn't apply to variable templates. */
2923 {
2927 {
2931 }
2932 }
2935 {
2941 /* Make sure that the declarator is a TEMPLATE_ID_EXPR. */
2943 {
2944 tree fns;
2949 else
2950 {
2951 /* If there is no class context, the explicit instantiation
2952 must be at namespace scope. */
2955 /* Find the namespace binding, using the declaration
2956 context. */
2960 {
2961 /* If lookup fails, look for a friend declaration so we can
2962 give a better diagnostic. */
2963 fns = (lookup_qualified_name
2968 }
2971 {
2974 }
2975 }
2978 }
2984 {
2986 /* A specialization in class scope. This is invalid,
2987 but the error will already have been flagged by
2988 check_specialization_scope. */
2990 else
2991 {
2992 /* It's not valid to write an explicit instantiation in
2993 class scope, e.g.:
2995 class C { template void f(); }
2997 This case is caught by the parser. However, on
2998 something like:
3000 template class C { void f(); };
3002 (which is invalid) we can get here. The error will be
3003 issued later. */
3004 ;
3005 }
3008 }
3011 {
3012 // We'll match variable templates in start_decl.
3016 /* Find the list of functions in ctype that have the same
3017 name as the declared function. */
3021 {
3025 {
3026 /* From [temp.expl.spec]:
3028 If such an explicit specialization for the member
3029 of a class template names an implicitly-declared
3030 special member function (clause _special_), the
3031 program is ill-formed.
3033 Similar language is found in [temp.explicit]. */
3036 }
3039 }
3041 /* For a type-conversion operator, We might be looking for
3042 `operator int' which will be a specialization of
3043 `operator T'. Grab all the conversion operators, and
3044 then select from them. */
3049 {
3052 }
3053 else
3055 }
3057 /* Figure out what exactly is being specialized at this point.
3058 Note that for an explicit instantiation, even one for a
3059 member function, we cannot tell a priori whether the
3060 instantiation is for a member template, or just a member
3061 function of a template class. Even if a member template is
3062 being instantiated, the member template arguments may be
3063 elided if they can be deduced from the rest of the
3064 declaration. */
3067 member_specialization,
3068 template_count,
3069 tsk);
3072 /* We couldn't figure out what this declaration was
3073 specializing. */
3075 else
3076 {
3078 {
3079 auto_diagnostic_group d;
3081 "friend declaration %qD is not visible to "
3085 }
3094 {
3095 /* We don't set DECL_EXPLICIT_INSTANTIATION here; that
3096 is done by do_decl_instantiation later. */
3102 {
3103 /* If TMPL is not the most general template (for
3104 example, if TMPL is a friend template that is
3105 injected into namespace scope), then there will
3106 be too many levels of TARGS. Remove some of them
3107 here. */
3109 tree new_targs;
3116 }
3119 }
3121 /* If we thought that the DECL was a member function, but it
3122 turns out to be specializing a static member function,
3123 make DECL a static member function as well. */
3129 /* If this is a specialization of a member template of a
3130 template class, we want to return the TEMPLATE_DECL, not
3131 the specialization of it. */
3133 {
3138 {
3139 tree parm;
3143 /* We want to use the argument list specified in the
3144 definition, not in the original declaration. */
3149 }
3154 }
3156 /* Set up the DECL_TEMPLATE_INFO for DECL. */
3162 /* Inherit default function arguments from the template
3163 DECL is specializing. */
3167 /* This specialization has the same protection as the
3168 template it specializes. */
3172 /* 7.1.1-1 [dcl.stc]
3174 A storage-class-specifier shall not be specified in an
3175 explicit specialization...
3177 The parser rejects these, so unless action is taken here,
3178 explicit function specializations will always appear with
3179 global linkage.
3181 The action recommended by the C++ CWG in response to C++
3182 defect report 605 is to make the storage class and linkage
3183 of the explicit specialization match the templated function:
3185 http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#605
3186 */
3188 {
3192 /* A concept cannot be specialized. */
3194 {
3196 gen_tmpl);
3198 }
3200 /* This specialization has the same linkage and visibility as
3201 the function template it specializes. */
3204 {
3207 }
3210 {
3213 }
3214 }
3216 /* If DECL is a friend declaration, declared using an
3217 unqualified name, the namespace associated with DECL may
3218 have been set incorrectly. For example, in:
3220 template <typename T> void f(T);
3221 namespace N {
3222 struct S { friend void f<int>(int); }
3223 }
3225 we will have set the DECL_CONTEXT for the friend
3226 declaration to N, rather than to the global namespace. */
3231 /* This is not really a declaration of a specialization.
3232 It's just the name of an instantiation. But, it's not
3233 a request for an instantiation, either. */
3236 /* A specialization is not necessarily COMDAT. */
3242 /* If this is a full specialization, register it so that we can find
3243 it again. Partial specializations will be registered in
3244 process_partial_specialization. */
3246 {
3251 }
3253 /* If this is a specialization, splice any contracts that may have
3254 been inherited from the template, removing them. */
3258 /* A 'structor should already have clones. */
3264 }
3265 }
3268 }
3270 /* Returns 1 iff PARMS1 and PARMS2 are identical sets of template
3271 parameters. These are represented in the same format used for
3272 DECL_TEMPLATE_PARMS. */
3274 int
3276 {
3291 {
3295 /* If either of the template parameters are invalid, assume
3296 they match for the sake of error recovery. */
3309 }
3312 }
3314 /* Returns true if two template parameters are declared with
3315 equivalent constraints. */
3317 static bool
3319 {
3327 }
3329 /* Returns true when two template parameters are equivalent. */
3331 static bool
3333 {
3337 /* If either of the template parameters are invalid, assume
3338 they match for the sake of error recovery. */
3342 /* ... they declare parameters of the same kind. */
3346 /* ... one parameter was introduced by a parameter declaration, then
3347 both are. This case arises as a result of eagerly rewriting declarations
3348 during parsing. */
3353 /* ... if either declares a pack, they both do. */
3358 {
3359 /* ... if they declare non-type parameters, the types are equivalent. */
3362 }
3364 {
3365 /* ... if they declare template template parameters, their template
3366 parameter lists are equivalent. */
3369 }
3371 /* ... if they are declared with a qualified-concept name, they both
3372 are, and those names are equivalent. */
3374 }
3376 /* Returns true if two template parameters lists are equivalent.
3377 Two template parameter lists are equivalent if they have the
3378 same length and their corresponding parameters are equivalent.
3380 PARMS1 and PARMS2 are TREE_LISTs containing TREE_VECs: the
3381 data structure returned by DECL_TEMPLATE_PARMS.
3383 This is generally the same implementation as comp_template_parms
3384 except that it also the concept names and arguments used to
3385 introduce parameters. */
3387 static bool
3389 {
3400 {
3405 }
3408 }
3410 /* Return true if the requires-clause of the template parameter lists are
3411 equivalent and false otherwise. */
3412 static bool
3414 {
3422 }
3424 /* Returns true if two template heads are equivalent. 17.6.6.1p6:
3425 Two template heads are equivalent if their template parameter
3426 lists are equivalent and their requires clauses are equivalent.
3428 In pre-C++20, this is equivalent to calling comp_template_parms
3429 for the template parameters of TMPL1 and TMPL2. */
3431 bool
3433 {
3437 /* Don't change the matching rules for pre-C++20. */
3441 /* ... have the same number of template parameters, and their
3442 corresponding parameters are equivalent. */
3446 /* ... if either has a requires-clause, they both do and their
3447 corresponding constraint-expressions are equivalent. */
3449 }
3451 /* Determine whether PARM is a parameter pack. */
3453 bool
3455 {
3456 /* Determine if we have a non-type template parameter pack. */
3463 /* If this is a list of template parameters, we could get a
3464 TYPE_DECL or a TEMPLATE_DECL. */
3468 /* Otherwise it must be a type template parameter. */
3472 }
3474 /* Determine if T is a function parameter pack. */
3476 bool
3478 {
3482 }
3484 /* Return the function template declaration of PRIMARY_FUNC_TMPL_INST.
3485 PRIMARY_FUNC_TMPL_INST is a primary function template instantiation. */
3487 tree
3489 {
3496 }
3498 /* Return true iff the function parameter PARAM_DECL was expanded
3499 from the function parameter pack PACK. */
3501 bool
3503 {
3508 /* The parameter pack and its pack arguments have the same
3509 DECL_PARM_INDEX. */
3511 }
3513 /* Determine whether ARGS describes a variadic template args list,
3514 i.e., one that is terminated by a template argument pack. */
3516 static bool
3518 {
3520 tree last_parm;
3534 }
3536 /* Generate a new name for the parameter pack name NAME (an
3537 IDENTIFIER_NODE) that incorporates its */
3539 static tree
3541 {
3542 /* Munge the name to include the parameter index. */
3543 #define NUMBUF_LEN 128
3557 }
3559 /* Return true if T is a primary function, class or alias template
3560 specialization, not including the template pattern. */
3562 bool
3564 {
3580 }
3582 /* Return true if PARM is a template template parameter. */
3584 bool
3586 {
3588 }
3590 /* Return true iff PARM is a DECL representing a type template
3591 parameter. */
3593 bool
3595 {
3600 }
3602 /* Return the template parameters of T if T is a
3603 primary template instantiation, NULL otherwise. */
3605 tree
3607 {
3612 parms = INNERMOST_TEMPLATE_PARMS
3616 }
3618 /* Returns the template arguments of T if T is a template instantiation,
3619 NULL otherwise. */
3621 tree
3623 {
3631 }
3633 /* Return the argument pack elements of T if T is a template argument pack,
3634 NULL otherwise. */
3636 tree
3638 {
3644 }
3646 /* In an ARGUMENT_PACK_SELECT, the actual underlying argument that the
3647 ARGUMENT_PACK_SELECT represents. */
3649 static tree
3651 {
3655 /* If the selected argument is an expansion E, that most likely means we were
3656 called from gen_elem_of_pack_expansion_instantiation during the
3657 substituting of an argument pack (of which the Ith element is a pack
3658 expansion, where I is ARGUMENT_PACK_SELECT_INDEX) into a pack expansion.
3659 In this case, the Ith element resulting from this substituting is going to
3660 be a pack expansion, which pattern is the pattern of E. Let's return the
3661 pattern of E, and gen_elem_of_pack_expansion_instantiation will build the
3662 resulting pack expansion from it. */
3664 {
3665 /* Make sure we aren't throwing away arg info. */
3668 }
3671 }
3673 /* Return a modification of ARGS that's suitable for preserving inside a hash
3674 table. In particular, this replaces each ARGUMENT_PACK_SELECT with its
3675 underlying argument. ARGS is copied (upon modification) iff COW_P. */
3677 static tree
3679 {
3684 {
3686 tree r;
3693 else
3696 {
3698 {
3701 }
3703 }
3704 }
3707 }
3709 /* True iff FN is a function representing a built-in variadic parameter
3710 pack. */
3712 bool
3714 {
3724 }
3726 /* True iff CALL is a call to a function representing a built-in variadic
3727 parameter pack. */
3729 static bool
3731 {
3735 }
3737 /* Return a TREE_VEC for the expansion of __integer_pack(HI). */
3739 static tree
3741 tree in_decl)
3742 {
3747 {
3749 {
3750 /* Work around maybe_convert_nontype_argument not doing this for
3751 dependent arguments. Don't use IMPLICIT_CONV_EXPR_NONTYPE_ARG
3752 because that will make tsubst_expr ignore it. */
3759 }
3764 }
3765 else
3766 {
3771 /* Calculate the largest value of len that won't make the size of the vec
3772 overflow an int. The compiler will exceed resource limits long before
3773 this, but it seems a decent place to diagnose. */
3777 {
3781 max);
3783 }
3791 }
3792 }
3794 /* Return a TREE_VEC for the expansion of built-in template parameter pack
3795 CALL. */
3797 static tree
3799 tree in_decl)
3800 {
3810 }
3812 /* Return true if the tree T has the extra args mechanism for
3813 avoiding partial instantiation. */
3815 static bool
3817 {
3822 }
3824 /* Structure used to track the progress of find_parameter_packs_r. */
3825 struct find_parameter_pack_data
3826 {
3827 /* TREE_LIST that will contain all of the parameter packs found by
3828 the traversal. */
3831 /* Set of AST nodes that have been visited by the traversal. */
3834 /* True iff we're making a type pack expansion. */
3837 /* True iff we found a subtree that has the extra args mechanism. */
3839 };
3841 /* Identifies all of the argument packs that occur in a template
3842 argument and appends them to the TREE_LIST inside DATA, which is a
3843 find_parameter_pack_data structure. This is a subroutine of
3844 make_pack_expansion and uses_parameter_packs. */
3845 static tree
3847 {
3853 #define WALK_SUBTREE(NODE) \
3854 cp_walk_tree (&(NODE), &find_parameter_packs_r, \
3855 ppd, ppd->visited) \
3857 /* Don't look through typedefs; we are interested in whether a
3858 parameter pack is actually written in the expression/type we're
3859 looking at, not the target type. */
3861 {
3862 /* But do look at arguments for an alias template. */
3869 }
3871 /* Identify whether this is a parameter pack or not. */
3873 {
3881 /* FALLTHRU */
3883 /* If the placeholder appears in the decl-specifier-seq of a function
3884 parameter pack (14.6.3), or the type-specifier-seq of a type-id that
3885 is a pack expansion, the invented template parameter is a template
3886 parameter pack. */
3896 {
3897 /* We don't want to walk into the type of a PARM_DECL,
3898 because we don't want to see the type parameter pack. */
3901 }
3906 {
3907 /* We don't want to walk into the type of a variadic capture proxy,
3908 because we don't want to see the type parameter pack. */
3911 }
3913 {
3915 find_parameter_packs_r,
3918 }
3930 /* Not a parameter pack. */
3932 }
3935 {
3936 /* Add this parameter pack to the list. */
3938 }
3947 /* This switch statement will return immediately if we don't find a
3948 parameter pack. ??? Should some of these be in cp_walk_subtrees? */
3950 {
3952 /* Check the template itself. */
3958 {
3960 /* Ignore the declaration of a capture proxy for a parameter pack. */
3964 /* Since we stop at typedefs above, we need to look through them at
3965 the point of the DECL_EXPR. */
3969 }
3996 {
3997 /* Since we defer implicit capture, look in the parms and body. */
4004 }
4007 {
4008 /* When traversing a DECLTYPE_TYPE_EXPR, we need to set
4009 type_pack_expansion_p to false so that any placeholders
4010 within the expression don't get marked as parameter packs. */
4018 }
4027 /* Don't walk into IF_STMT_EXTRA_ARGS. */
4034 {
4035 /* Local class, need to look through the whole definition.
4036 TYPE_BINFO might be unset for a partial instantiation. */
4041 }
4042 else
4043 /* Enum, look at the values. */
4057 }
4059 #undef WALK_SUBTREE
4062 }
4064 /* Determines if the expression or type T uses any parameter packs. */
4065 tree
4067 {
4076 }
4078 /* Turn ARG, which may be an expression, type, or a TREE_LIST
4079 representation a base-class initializer into a parameter pack
4080 expansion. If all goes well, the resulting node will be an
4081 EXPR_PACK_EXPANSION, TYPE_PACK_EXPANSION, or TREE_LIST,
4082 respectively. */
4083 tree
4085 {
4086 tree result;
4095 {
4096 /* A TREE_LIST with a non-null TREE_PURPOSE is for a base
4097 class initializer. In this case, the TREE_PURPOSE will be a
4098 _TYPE node (representing the base class expansion we're
4099 initializing) and the TREE_VALUE will be a TREE_LIST
4100 containing the initialization arguments.
4102 The resulting expansion looks somewhat different from most
4103 expansions. Rather than returning just one _EXPANSION, we
4104 return a TREE_LIST whose TREE_PURPOSE is a
4105 TYPE_PACK_EXPANSION containing the bases that will be
4106 initialized. The TREE_VALUE will be identical to the
4107 original TREE_VALUE, which is a list of arguments that will
4108 be passed to each base. We do not introduce any new pack
4109 expansion nodes into the TREE_VALUE (although it is possible
4110 that some already exist), because the TREE_PURPOSE and
4111 TREE_VALUE all need to be expanded together with the same
4112 _EXPANSION node. Note that the TYPE_PACK_EXPANSION in the
4113 resulting TREE_PURPOSE will mention the parameter packs in
4114 both the bases and the arguments to the bases. */
4115 tree purpose;
4116 tree value;
4119 /* Determine which parameter packs will be used by the base
4120 class expansion. */
4129 {
4132 arg);
4135 }
4138 {
4139 /* Collect the sets of parameter packs used in each of the
4140 initialization arguments. */
4142 {
4143 /* Determine which parameter packs will be expanded in this
4144 argument. */
4147 }
4148 }
4152 /* Create the pack expansion type for the base type. */
4158 /* Just use structural equality for these TYPE_PACK_EXPANSIONS;
4159 they will rarely be compared to anything. */
4163 }
4168 /* Build the PACK_EXPANSION_* node. */
4169 result = for_types
4174 {
4175 /* Propagate type and const-expression information. */
4178 /* Mark this read now, since the expansion might be length 0. */
4180 }
4181 else
4182 /* Just use structural equality for these TYPE_PACK_EXPANSIONS;
4183 they will rarely be compared to anything. */
4186 /* Determine which parameter packs will be expanded. */
4193 /* Make sure we found some parameter packs. */
4195 {
4197 {
4200 else
4202 }
4204 }
4209 /* If the pattern of this pack expansion contains a subtree that has
4210 the extra args mechanism for avoiding partial instantiation, then
4211 force this pack expansion to also use extra args. Otherwise
4212 partial instantiation of this pack expansion may not lower the
4213 level of some parameter packs within the pattern, which would
4214 confuse tsubst_pack_expansion later (PR101764). */
4218 }
4220 /* Checks T for any "bare" parameter packs, which have not yet been
4221 expanded, and issues an error if any are found. This operation can
4222 only be done on full expressions or types (e.g., an expression
4223 statement, "if" condition, etc.), because we could have expressions like:
4225 foo(f(g(h(args)))...)
4227 where "args" is a parameter pack. check_for_bare_parameter_packs
4228 should not be called for the subexpressions args, h(args),
4229 g(h(args)), or f(g(h(args))), because we would produce erroneous
4230 error messages.
4232 Returns TRUE and emits an error if there were bare parameter packs,
4233 returns FALSE otherwise. */
4234 bool
4236 {
4258 /* It's OK for a lambda to have an unexpanded parameter pack from the
4259 containing context, but do complain about unexpanded capture packs. */
4265 {
4266 /* We're in a lambda, but it isn't the innermost class.
4267 This should work, but currently doesn't. */
4270 }
4275 {
4281 }
4284 {
4287 {
4298 else
4303 else
4307 }
4310 }
4313 }
4315 /* Expand any parameter packs that occur in the template arguments in
4316 ARGS. */
4317 tree
4319 {
4328 /* First, determine if we need to expand anything, and the number of
4329 slots we'll need. */
4331 {
4336 {
4340 else
4342 }
4343 else
4344 {
4346 num_result_args++;
4347 }
4348 }
4350 /* If no expansion is necessary, we're done. */
4354 /* Expand arguments. */
4357 non_default_args_count =
4360 {
4363 {
4370 }
4371 else
4372 {
4375 }
4376 }
4380 }
4382 /* Checks if DECL shadows a template parameter.
4384 [temp.local]: A template-parameter shall not be redeclared within its
4385 scope (including nested scopes).
4387 Emits an error and returns TRUE if the DECL shadows a parameter,
4388 returns FALSE otherwise. */
4390 bool
4392 {
4393 tree olddecl;
4395 /* If we're not in a template, we can't possibly shadow a template
4396 parameter. */
4400 /* Figure out what we're shadowing. */
4404 /* If there's no previous binding for this name, we're not shadowing
4405 anything, let alone a template parameter. */
4409 /* If we're not shadowing a template parameter, we're done. Note
4410 that OLDDECL might be an OVERLOAD (or perhaps even an
4411 ERROR_MARK), so we can't just blithely assume it to be a _DECL
4412 node. */
4416 /* We check for decl != olddecl to avoid bogus errors for using a
4417 name inside a class. We check TPFI to avoid duplicate errors for
4418 inline member templates. */
4424 /* Don't complain about the injected class name, as we've already
4425 complained about the class itself. */
4432 else
4437 }
4439 /* Return a new TEMPLATE_PARM_INDEX with the indicated INDEX, LEVEL,
4440 ORIG_LEVEL, DECL, and TYPE. */
4442 static tree
4446 tree decl,
4447 tree type)
4448 {
4459 }
4462 {
4464 {
4474 }
4477 {
4482 }
4483 };
4487 /* Find the canonical type parameter for the given template type
4488 parameter. Returns the canonical type parameter, which may be TYPE
4489 if no such parameter existed. */
4491 tree
4493 {
4501 }
4503 /* Return a TEMPLATE_PARM_INDEX, similar to INDEX, but whose
4504 TEMPLATE_PARM_LEVEL has been decreased by LEVELS. If such a
4505 TEMPLATE_PARM_INDEX already exists, it is returned; otherwise, a
4506 new one is created. */
4508 static tree
4510 tsubst_flags_t complain)
4511 {
4516 {
4521 type);
4536 /* Template template parameters need this. */
4539 {
4551 }
4553 /* Attach the TPI to the decl. */
4556 else
4558 }
4561 }
4563 /* Process information from new template parameter PARM and append it
4564 to the LIST being built. This new parameter is a non-type
4565 parameter iff IS_NON_TYPE is true. This new parameter is a
4566 parameter pack iff IS_PARAMETER_PACK is true. The location of PARM
4567 is in PARM_LOC. */
4569 tree
4572 {
4578 {
4588 }
4595 {
4601 {
4602 /* [temp.param]
4604 The top-level cv-qualifiers on the template-parameter are
4605 ignored when determining its type. */
4610 && !is_parameter_pack
4611 /* If we're in a nested template parameter list, the template
4612 template parameter could be a parameter pack. */
4614 {
4615 /* This template parameter is not a parameter pack, but it
4616 should be. Complain about "bare" parameter packs. */
4619 /* Recover by calling this a parameter pack. */
4621 }
4622 }
4624 /* A template parameter is not modifiable. */
4633 current_template_depth,
4638 }
4639 else
4640 {
4641 tree t;
4645 {
4647 /* This is for distinguishing between real templates and template
4648 template parameters */
4651 /* any_template_parm_r expects to be able to get the targs of a
4652 DECL_TEMPLATE_RESULT. */
4661 }
4662 else
4663 {
4665 /* parm is either IDENTIFIER_NODE or NULL_TREE. */
4668 }
4675 current_template_depth,
4679 }
4687 /* Build requirements for the type/template parameter.
4688 This must be done after SET_DECL_TEMPLATE_PARM_P or
4689 process_template_parm could fail. */
4696 /* Build the parameter node linking the parameter declaration,
4697 its default argument (if any), and its constraints (if any). */
4703 else
4707 }
4709 /* The end of a template parameter list has been reached. Process the
4710 tree list into a parameter vector, converting each parameter into a more
4711 useful form. Type parameters are saved as IDENTIFIER_NODEs, and others
4712 as PARM_DECLs. */
4714 tree
4716 {
4719 /* Pop the dummy parameter level and add the real one. We do not
4720 morph the dummy parameter in place, as it might have been
4721 captured by a (nested) template-template-parm. */
4724 current_template_parms
4729 {
4735 }
4740 }
4742 // Explicitly indicate the end of the template parameter list. We assume
4743 // that the current template parameters have been constructed and/or
4744 // managed explicitly, as when creating new template template parameters
4745 // from a shorthand constraint.
4746 void
4748 {
4750 }
4752 /* end_template_decl is called after a template declaration is seen. */
4754 void
4756 {
4762 /* This matches the pushlevel in begin_template_parm_list. */
4767 }
4769 /* Takes a TEMPLATE_PARM_P or DECL_TEMPLATE_PARM_P node or a TREE_LIST
4770 thereof, and converts it into an argument suitable to be passed to
4771 the type substitution functions. Note that if the TREE_LIST contains
4772 an error_mark node, the returned argument is error_mark_node. */
4774 tree
4776 {
4787 {
4791 else
4793 }
4799 {
4801 {
4802 /* Turn this argument into a TYPE_ARGUMENT_PACK
4803 with a single element, which expands T. */
4812 }
4813 }
4814 else
4815 {
4817 {
4818 /* Turn this argument into a NONTYPE_ARGUMENT_PACK
4819 with a single element, which expands T. */
4829 }
4830 else
4832 }
4834 }
4836 /* If T looks like a generic template argument produced by template_parm_to_arg,
4837 return the corresponding template parameter, otherwise return NULL_TREE. */
4839 static tree
4841 {
4846 {
4851 }
4858 else
4860 }
4862 /* Given a single level of template parameters (a TREE_VEC), return it
4863 as a set of template arguments. */
4865 tree
4867 {
4877 }
4879 /* Given a set of template parameters, return them as a set of template
4880 arguments. The template parameters are represented as a TREE_VEC, in
4881 the form documented in cp-tree.h for template arguments. */
4883 tree
4885 {
4886 tree header;
4891 /* If there is only one level of template parameters, we do not
4892 create a TREE_VEC of TREE_VECs. Instead, we return a single
4893 TREE_VEC containing the arguments. */
4898 {
4903 else
4905 }
4908 }
4910 /* Within the declaration of a template, return the currently active
4911 template parameters as an argument TREE_VEC. */
4913 static tree
4915 {
4917 }
4919 /* Return the fully generic arguments for of TMPL, i.e. what
4920 current_template_args would be while parsing it. */
4922 tree
4924 {
4929 /* DECL_TEMPLATE_RESULT doesn't have the arguments we want. For a template
4930 template parameter, it has no TEMPLATE_INFO; for a partial
4931 specialization, it has the arguments for the primary template, and we
4937 }
4939 /* Return the template arguments corresponding to the template parameters of
4940 DECL's enclosing scope. When DECL is a member of a partial specialization,
4941 this returns the arguments for the partial specialization as opposed to those
4942 for the primary template, which is the main difference between this function
4943 and simply using e.g. the TYPE_TI_ARGS of DECL's DECL_CONTEXT. */
4945 tree
4947 {
4959 }
4961 /* Update the declared TYPE by doing any lookups which were thought to be
4962 dependent, but are not now that we know the SCOPE of the declarator. */
4964 tree
4966 {
4977 /* Don't bother building up the args in this case. */
4979 {
4980 /* tsubst in the args corresponding to the template parameters,
4981 including auto if present. Most things will be unchanged, but
4982 make_typename_type and tsubst_qualified_id will resolve
4983 TYPENAME_TYPEs and SCOPE_REFs that were previously dependent. */
4986 tree pushed;
4988 {
4992 }
4997 }
5003 {
5006 else
5008 }
5010 }
5012 /* Return a TEMPLATE_DECL corresponding to DECL, using the indicated
5013 template PARMS and constraints, CONSTR. If MEMBER_TEMPLATE_P is true,
5014 the new template is a member template. */
5016 static tree
5018 {
5030 /* Propagate module information from the decl. */
5034 }
5036 struct template_parm_data
5037 {
5038 /* The level of the template parameters we are currently
5039 processing. */
5042 /* The index of the specialization argument we are currently
5043 processing. */
5046 /* An array whose size is the number of template parameters. The
5047 elements are nonzero if the parameter has been used in any one
5048 of the arguments processed so far. */
5051 /* An array whose size is the number of template arguments. The
5052 elements are nonzero if the argument makes use of template
5053 parameters of this level. */
5055 };
5057 /* Subroutine of push_template_decl used to see if each template
5058 parameter in a partial specialization is used in the explicit
5059 argument list. If T is of the LEVEL given in DATA (which is
5060 treated as a template_parm_data*), then DATA->PARMS is marked
5061 appropriately. */
5063 static int
5065 {
5073 {
5076 }
5078 /* In C++17 the type of a non-type argument is a deduced context. */
5083 data,
5084 NULL,
5087 /* Return zero so that for_each_template_parm will continue the
5088 traversal of the tree; we want to mark *every* template parm. */
5090 }
5092 /* Process the partial specialization DECL. */
5094 static tree
5096 {
5103 tree inner_parms;
5104 tree inst;
5114 /* A concept cannot be specialized. */
5116 {
5119 }
5124 /* We check that each of the template parameters given in the
5125 partial specialization is used in the argument list to the
5126 specialization. For example:
5128 template <class T> struct S;
5129 template <class T> struct S<T*>;
5131 The second declaration is OK because `T*' uses the template
5132 parameter T, whereas
5134 template <class T> struct S<int>;
5136 is no good. Even trickier is:
5138 template <class T>
5139 struct S1
5140 {
5141 template <class U>
5142 struct S2;
5143 template <class U>
5144 struct S2<T>;
5145 };
5147 The S2<T> declaration is actually invalid; it is a
5148 full-specialization. Of course,
5150 template <class U>
5151 struct S2<T (*)(U)>;
5153 or some such would have been OK. */
5161 {
5166 NULL,
5168 }
5171 {
5172 /* One of the template parms was not used in a deduced context in the
5173 specialization. */
5175 {
5179 }
5183 }
5188 /* [temp.class.spec]
5190 The argument list of the specialization shall not be identical to
5191 the implicit argument list of the primary template. */
5192 tree main_args
5195 && (!flag_concepts
5197 {
5200 "any template arguments; to define the primary template, "
5202 else
5204 "template arguments and is not more constrained than "
5205 "the primary template; to define the primary template, "
5208 }
5210 /* A partial specialization that replaces multiple parameters of the
5211 primary template with a pack expansion is less specialized for those
5212 parameters. */
5214 {
5216 "primary template because it replaces multiple parameters "
5219 /* Avoid crash in process_partial_specialization. */
5221 }
5224 {
5227 /* Avoid crash below. */
5229 }
5231 /* If we aren't in a dependent class, we can actually try deduction. */
5233 /* FIXME we should be able to handle a partial specialization of a
5234 partial instantiation, but currently we can't (c++/41727). */
5237 {
5238 auto_diagnostic_group d;
5241 decl))
5243 maintmpl);
5244 }
5246 /* [temp.spec.partial]
5248 The type of a template parameter corresponding to a specialized
5249 non-type argument shall not be dependent on a parameter of the
5250 specialization.
5252 Also, we verify that pack expansions only occur at the
5253 end of the argument list. */
5256 {
5263 {
5264 /* Extract the arguments from the argument pack. We'll be
5265 iterating over these in the following loop. */
5268 }
5271 {
5273 /* Get the Jth argument in the parameter pack. */
5277 {
5278 /* Pack expansions must come at the end of the
5279 argument list. */
5282 {
5286 else
5289 }
5290 }
5293 /* We only care about the pattern. */
5299 /* This next two lines are the `argument expression is not just a
5300 simple identifier' condition and also the `specialized
5301 non-type argument' bit. */
5306 {
5307 /* Look at the corresponding template parameter,
5308 marking which template parameters its type depends
5309 upon. */
5313 {
5314 /* We haven't yet initialized TPD2. Do so now. */
5316 /* The number of parameters here is the number in the
5317 main template, which, as checked in the assertion
5318 above, is NARGS. */
5322 }
5324 /* Mark the template parameters. But this time, we're
5325 looking for the template parameters of the main
5326 template, not in the specialization. */
5333 NULL,
5337 {
5338 /* The type depended on some template parameters.
5339 If they are fully specialized in the
5340 specialization, that's OK. */
5349 "type %qT of template argument %qE depends "
5351 "type %qT of template argument %qE depends "
5353 type,
5354 arg);
5355 }
5356 }
5357 }
5358 }
5360 /* We should only get here once. */
5364 // Build the template decl.
5371 /* Give template template parms a DECL_CONTEXT of the template
5372 for which they are a parameter. */
5374 {
5378 }
5381 /* We didn't register this in check_explicit_specialization so we could
5382 wait until the constraints were set. */
5384 else
5391 /* Link the DECL_TEMPLATE_RESULT back to the partial TEMPLATE_DECL. */
5397 {
5403 {
5412 "declaration of %qD ambiguates earlier template "
5416 "partial specialization of %qD after instantiation "
5418 }
5419 }
5422 }
5424 /* PARM is a template parameter of some form; return the corresponding
5425 TEMPLATE_PARM_INDEX. */
5427 static tree
5429 {
5442 }
5444 /* Subroutine of fixed_parameter_pack_p below. Look for any template
5445 parameter packs used by the template parameter PARM. */
5447 static void
5449 {
5450 /* A type parm can't refer to another parm. */
5454 {
5458 }
5464 {
5468 else
5470 }
5471 }
5473 /* PARM is a template parameter pack. Return any parameter packs used in
5474 its type or the type of any of its template parameters. If there are
5475 any such packs, it will be instantiated into a fixed template parameter
5476 list by partial instantiation rather than be fully deduced. */
5478 tree
5480 {
5481 /* This can only be true in a member template. */
5484 /* This can only be true for a parameter pack. */
5487 /* A type parm can't refer to another parm. */
5501 }
5503 /* Check that a template declaration's use of default arguments and
5504 parameter packs is not invalid. Here, PARMS are the template
5505 parameters. IS_PRIMARY is true if DECL is the thing declared by
5506 a primary template. IS_PARTIAL is true if DECL is a partial
5507 specialization.
5509 IS_FRIEND_DECL is nonzero if DECL is either a non-defining friend
5510 function template declaration or a friend class template
5511 declaration. In the function case, 1 indicates a declaration, 2
5512 indicates a redeclaration. When IS_FRIEND_DECL=2, no errors are
5513 emitted for extraneous default arguments.
5515 Returns TRUE if there were no errors found, FALSE otherwise. */
5517 bool
5520 {
5523 tree parm_level;
5526 /* [temp.param]
5528 A default template-argument shall not be specified in a
5529 function template declaration or a function template definition, nor
5530 in the template-parameter-list of the definition of a member of a
5531 class template. */
5535 /* You can't have a function template declaration in a local
5536 scope, nor you can you define a member of a class template in a
5537 local scope. */
5545 /* A lambda doesn't have an explicit declaration; don't complain
5546 about the parms of the enclosing class. */
5553 /* If this is either a friend defined in the scope of the class
5554 or a member function. */
5560 /* And, if it was a member function, it really was defined in
5561 the scope of the class. */
5564 /* We already checked these parameters when the template was
5565 declared, so there's no need to do it again now. This function
5566 was defined in class scope, but we're processing its body now
5567 that the class is complete. */
5570 /* Core issue 226 (C++0x only): the following only applies to class
5571 templates. */
5574 {
5575 /* [temp.param]
5577 If a template-parameter has a default template-argument, all
5578 subsequent template-parameters shall have a default
5579 template-argument supplied. */
5581 {
5588 {
5598 {
5600 /* For better subsequent error-recovery, we indicate that
5601 there should have been a default argument. */
5604 }
5606 && !is_friend_decl
5607 /* Don't complain about an enclosing partial
5608 specialization. */
5613 /* A fixed parameter pack will be partially
5614 instantiated into a fixed length list. */
5616 {
5617 /* A primary class template, primary variable template
5618 (DR 2032), or alias template can only have one
5619 parameter pack, at the end of the template
5620 parameter list. */
5628 }
5629 }
5630 }
5631 }
5634 || is_partial
5635 || !is_primary
5637 /* For an ordinary class template, default template arguments are
5638 allowed at the innermost level, e.g.:
5639 template <class T = int>
5640 struct S {};
5641 but, in a partial specialization, they're not allowed even
5642 there, as we have in [temp.class.spec]:
5644 The template parameter list of a specialization shall not
5645 contain default template argument values.
5647 So, for a partial specialization, or for a function template
5648 (in C++98/C++03), we look at all of them. */
5649 ;
5650 else
5651 /* But, for a primary class template that is not a partial
5652 specialization we look at all template parameters except the
5653 innermost ones. */
5656 /* Figure out what error message to issue. */
5671 else
5672 /* Per [temp.param]/9, "A default template-argument shall not be
5673 specified in the template-parameter-lists of the definition of
5674 a member of a class template that appears outside of the member's
5675 class.", thus if we aren't handling a member of a class template
5676 there is no need to examine the parameters. */
5680 /* If we're inside a class definition, there's no need to
5681 examine the parameters to the class itself. On the one
5682 hand, they will be checked when the class is defined, and,
5683 on the other, default arguments are valid in things like:
5684 template <class T = double>
5685 struct S { template <class U> void f(U); };
5686 Here the default argument for `S' has no bearing on the
5687 declaration of `f'. */
5689 else
5690 /* Check everything. */
5696 {
5703 {
5708 {
5710 {
5717 }
5719 /* Clear out the default argument so that we are not
5720 confused later. */
5722 }
5723 }
5725 /* At this point, if we're still interested in issuing messages,
5726 they must apply to classes surrounding the object declared. */
5730 }
5733 }
5735 /* Worker for push_template_decl_real, called via
5736 for_each_template_parm. DATA is really an int, indicating the
5737 level of the parameters we are interested in. If T is a template
5738 parameter of that level, return nonzero. */
5740 static int
5742 {
5748 else
5751 }
5753 /* Worker for uses_outer_template_parms, called via for_each_template_parm.
5754 DATA is really an int, indicating the innermost outer level of parameters.
5755 If T is a template parameter of that level or further out, return
5756 nonzero. */
5758 static int
5760 {
5766 else
5769 }
5771 /* Creates a TEMPLATE_DECL for the indicated DECL using the template
5772 parameters given by current_template_args, or reuses a
5773 previously existing one, if appropriate. Returns the DECL, or an
5774 equivalent one, if it is replaced via a call to duplicate_decls.
5776 If IS_FRIEND is true, DECL is a friend declaration. */
5778 tree
5780 {
5784 /* See if this is a partial specialization. */
5793 /* No surprising friend functions. */
5798 tree ctx;
5800 /* For a friend, we want the context of the friend, not
5801 the type of which it is a friend. */
5805 /* In the case of a virtual function, we want the class in which
5806 it is defined. */
5808 else
5809 /* Otherwise, if we're currently defining some class, the DECL
5810 is assumed to be a member of the class. */
5819 /* See if this is a primary template. */
5823 /* A friend template that specifies a class context, i.e.
5824 template <typename T> friend void A<T>::f();
5825 is not primary. */
5826 ;
5828 /* Lambdas are not primary. */
5829 ;
5830 else
5833 /* True if the template is a member template, in the sense of
5834 [temp.mem]. */
5838 {
5846 {
5849 }
5851 {
5853 {
5856 }
5858 {
5859 /* [temp.mem]
5861 A destructor shall not be a member template. */
5865 }
5872 {
5873 /* [basic.stc.dynamic.allocation]
5875 An allocation function can be a function
5876 template. ... Template allocation functions shall
5877 have two or more parameters. */
5880 }
5881 }
5887 /* alias-declaration */
5893 else
5894 {
5897 }
5898 }
5905 /* Check to see that the rules regarding the use of default
5906 arguments are not being violated. We check args for a friend
5907 functions when we know whether it's a definition, introducing
5908 declaration or re-declaration. */
5913 /* Ensure that there are no parameter packs in the type of this
5914 declaration that have not been expanded. */
5916 {
5917 /* Check each of the arguments individually to see if there are
5918 any bare parameter packs. */
5924 {
5927 {
5928 /* This is a PARM_DECL that contains unexpanded parameter
5929 packs. We have already complained about this in the
5930 check_for_bare_parameter_packs call, so just replace
5931 these types with ERROR_MARK_NODE. */
5934 }
5938 }
5940 /* Check for bare parameter packs in the return type and the
5941 exception specifiers. */
5943 /* Errors were already issued, set return type to int
5944 as the frontend doesn't expect error_mark_node as
5945 the return type. */
5949 }
5950 else
5951 {
5955 {
5958 }
5963 }
5972 {
5973 /* Does not get a template head. */
5976 }
5983 {
5988 /* If DECL is a TYPE_DECL for a class-template, then there won't
5989 be DECL_LANG_SPECIFIC. The information equivalent to
5990 DECL_TEMPLATE_INFO is found in TYPE_TEMPLATE_INFO instead. */
5994 {
5995 /* Since a template declaration already existed for this
5996 class-type, we must be redeclaring it here. Make sure
5997 that the redeclaration is valid. */
5999 current_template_parms,
6001 /* We don't need to create a new TEMPLATE_DECL; just use the
6002 one we already had. */
6004 }
6005 else
6006 {
6008 member_template_p);
6013 {
6014 /* A specialization of a member template of a template
6015 class. */
6019 }
6020 }
6021 }
6022 else
6023 {
6029 {
6032 }
6040 {
6041 /* The declaration is a specialization of a member
6042 template, declared outside the class. Therefore, the
6043 innermost template arguments will be NULL, so we
6044 replace them with the arguments determined by the
6045 earlier call to check_explicit_specialization. */
6048 tree new_tmpl
6050 member_template_p);
6058 args,
6061 }
6063 /* Make sure the template headers we got make sense. */
6068 {
6073 }
6074 else
6076 {
6081 {
6085 else
6089 /* Avoid crash in import_export_decl. */
6092 }
6097 /* Can happen in erroneous input. */
6099 else
6101 }
6103 /* Check that the parms are used in the appropriate qualifying scopes
6104 in the declarator. */
6108 {
6114 /* Avoid crash in import_export_decl. */
6117 }
6119 /* Check that the constraints for each enclosing template scope are
6120 consistent with the original declarations. */
6122 {
6126 {
6129 }
6131 {
6133 {
6137 }
6140 }
6141 }
6142 }
6147 {
6148 /* Push template declarations for global functions and types.
6149 Note that we do not try to push a global template friend
6150 declared in a template class; such a thing may well depend on
6151 the template parameters of the class and we'll push it when
6152 instantiating the befriending class. */
6155 {
6160 /* pushdecl may have found an existing template. */
6162 {
6165 }
6166 }
6168 {
6169 /* Record this decl as belonging to the current class. It's
6170 not chained onto anything else. */
6174 }
6175 }
6177 /* The type may have been completed, or (erroneously) changed. */
6181 {
6183 {
6188 /* Give template template parms a DECL_CONTEXT of the template
6189 for which they are a parameter. */
6192 {
6196 }
6200 {
6203 {
6204 /* ??? Why don't we do this here for all templates? */
6207 }
6210 }
6211 }
6213 /* The DECL_TI_ARGS of DECL contains full set of arguments
6214 referring wback to its most general template. If TMPL is a
6215 specialization, ARGS may only have the innermost set of
6216 arguments. Add the missing argument levels if necessary. */
6224 else
6225 {
6228 }
6229 }
6232 && !is_friend
6235 /* Set DECL_COMDAT on template instantiations; if we force
6236 them to be emitted by explicit instantiation,
6237 mark_needed will tell cgraph to do the right thing. */
6243 }
6245 /* FN is an inheriting constructor that inherits from the constructor
6246 template INHERITED; turn FN into a constructor template with a matching
6247 template header. */
6249 tree
6251 {
6252 tree inner_parms
6255 tree parms
6264 }
6266 /* Called when a class template TYPE is redeclared with the indicated
6267 template PARMS, e.g.:
6269 template <class T> struct S;
6270 template <class T> struct S {}; */
6272 bool
6274 {
6275 tree tmpl;
6276 tree tmpl_parms;
6280 {
6283 }
6287 /* The type is nested in some template class. Nothing to worry
6288 about here; there are no new template parameters for the nested
6289 type. */
6293 {
6295 tmpl);
6297 }
6303 {
6313 }
6316 {
6317 tree tmpl_parm;
6318 tree parm;
6330 /* TMPL_PARM and PARM can be either TYPE_DECL, PARM_DECL, or
6331 TEMPLATE_DECL. */
6341 {
6342 auto_diagnostic_group d;
6346 else
6349 }
6351 /* The parameters can be declared to introduce different
6352 constraints. */
6356 {
6357 auto_diagnostic_group d;
6363 }
6365 /* Give each template template parm in this redeclaration a
6366 DECL_CONTEXT of the template for which they are a parameter. */
6368 {
6372 }
6373 }
6382 /* Two classes with different constraints declare different entities. */
6384 {
6385 auto_diagnostic_group d;
6391 }
6394 }
6396 /* The actual substitution part of instantiate_non_dependent_expr,
6397 to be used when the caller has already checked
6398 !instantiation_dependent_uneval_expression_p (expr)
6399 and cleared processing_template_decl. */
6401 tree
6403 {
6405 }
6407 /* Instantiate the non-dependent expression EXPR. */
6409 tree
6412 {
6417 {
6418 /* The caller should have checked this already. */
6420 processing_template_decl_sentinel s;
6422 }
6424 }
6426 /* Like instantiate_non_dependent_expr, but return NULL_TREE if the
6427 expression is dependent or non-constant. */
6429 tree
6431 {
6435 {
6438 else
6439 {
6440 processing_template_decl_sentinel s;
6442 }
6443 }
6445 }
6447 /* True iff T is a specialization of a variable template. */
6449 bool
6451 {
6456 }
6458 /* Return TRUE iff T is a type alias, a TEMPLATE_DECL for an alias
6459 template declaration, or a TYPE_DECL for an alias declaration. */
6461 bool
6463 {
6471 }
6473 /* If T is a specialization of an alias template, return it; otherwise return
6474 NULL_TREE. If TRANSPARENT_TYPEDEFS is true, look through other aliases. */
6476 tree
6479 {
6483 /* It's an alias template specialization if it's an alias and its
6484 TYPE_NAME is a specialization of a primary template. */
6486 {
6493 transparent_typedefs);
6494 }
6497 }
6499 /* Data structure for complex_alias_template_*. */
6501 struct uses_all_template_parms_data
6502 {
6505 };
6507 /* walk_tree callback for complex_alias_template_p. */
6509 static tree
6511 {
6516 {
6521 {
6525 }
6528 }
6533 /* An alias template with a pack expansion that expands a pack from the
6534 enclosing class needs to be considered complex, to avoid confusion with
6535 the same pack being used as an argument to the alias's own template
6536 parameter (91966). */
6539 {
6548 /* Consider the expanded packs to be used outside the expansion... */
6550 }
6552 /* ...but don't walk into the pattern. Consider PR104008:
6554 template <typename T, typename... Ts>
6555 using IsOneOf = disjunction<is_same<T, Ts>...>;
6557 where IsOneOf seemingly uses all of its template parameters in its
6558 expansion (and does not expand a pack from the enclosing class), so the
6559 alias was not marked as complex. However, if it is used like
6560 "IsOneOf<T>", the empty pack for Ts means that T no longer appears in the
6561 expansion. So only Ts is considered used by the pack expansion. */
6565 }
6567 /* An alias template is complex from a SFINAE perspective if a template-id
6568 using that alias can be ill-formed when the expansion is not, as with
6569 the void_t template.
6571 Returns 1 if always complex, 0 if not complex, -1 if complex iff any of the
6572 template arguments are empty packs. */
6574 static bool
6576 {
6577 /* A renaming alias isn't complex. */
6581 /* Any other constrained alias is complex. */
6600 }
6602 /* If T is a specialization of a complex alias template with dependent
6603 template-arguments, return it; otherwise return NULL_TREE. If T is a
6604 typedef to such a specialization, return the specialization. */
6606 tree
6608 {
6619 && (any_dependent_template_arguments_p
6624 {
6627 }
6630 }
6632 /* Return the number of innermost template parameters in TMPL. */
6634 static int
6636 {
6639 }
6641 /* Return either TMPL or another template that it is equivalent to under DR
6642 1286: An alias that just changes the name of a template is equivalent to
6643 the other template. */
6645 static tree
6647 {
6650 {
6651 /* Determine if the alias is equivalent to an underlying template. */
6653 /* The underlying type may have been ill-formed. Don't proceed. */
6666 /* Does the alias add cv-quals? */
6674 /* Are any default template arguments equivalent? */
6679 {
6684 }
6686 /* If TMPL adds or changes any constraints, it isn't equivalent. I think
6687 it's appropriate to treat a less-constrained alias as equivalent. */
6691 /* Alias is equivalent. Strip it and repeat. */
6693 }
6694 top_break:;
6697 }
6699 /* Subroutine of convert_nontype_argument. Converts EXPR to TYPE, which
6700 must be a reference-to-function or a pointer-to-function type, as specified
6701 in [temp.arg.nontype]: disambiguate EXPR if it is an overload set,
6702 and check that the resulting function has external linkage. */
6704 static tree
6706 tsubst_flags_t complain)
6707 {
6710 linkage_kind linkage;
6728 /* [temp.arg.nontype]/1
6730 A template-argument for a non-type, non-template template-parameter
6731 shall be one of:
6732 [...]
6733 -- the address of an object or function with external [C++11: or
6734 internal] linkage. */
6738 {
6740 {
6747 else
6750 }
6752 }
6757 {
6759 {
6765 else
6769 }
6771 }
6773 accept:
6775 {
6778 else
6780 }
6785 }
6787 /* Subroutine of convert_nontype_argument.
6788 Check if EXPR of type TYPE is a valid pointer-to-member constant.
6789 Emit an error otherwise. */
6791 static bool
6793 tsubst_flags_t complain)
6794 {
6810 {
6816 else
6818 }
6820 }
6822 /* Returns TRUE iff the address of OP is value-dependent.
6824 14.6.2.4 [temp.dep.temp]:
6825 A non-integral non-type template-argument is dependent if its type is
6826 dependent or it has either of the following forms
6827 qualified-id
6828 & qualified-id
6829 and contains a nested-name-specifier which specifies a class-name that
6830 names a dependent type.
6832 We generalize this to just say that the address of a member of a
6833 dependent class is value-dependent; the above doesn't cover the
6834 address of a static data member named with an unqualified-id. */
6836 static bool
6838 {
6841 /* We could use get_inner_reference here, but there's no need;
6842 this is only relevant for template non-type arguments, which
6843 can only be expressed as &id-expression. */
6845 {
6856 }
6859 }
6861 /* The next set of functions are used for providing helpful explanatory
6862 diagnostics for failed overload resolution. Their messages should be
6863 indented by two spaces for consistency with the messages in
6864 call.cc */
6866 static int
6868 {
6870 }
6872 /* Other failure functions should call this one, to provide a single function
6873 for setting a breakpoint on. */
6875 static int
6877 {
6879 }
6881 static int
6883 {
6888 }
6890 static int
6892 {
6898 }
6900 static int
6902 {
6906 }
6908 static int
6910 {
6913 " template parameter %qD is not a parameter pack, but "
6917 }
6919 static int
6921 {
6924 " template argument %qE does not match "
6928 }
6930 static int
6932 {
6936 }
6938 static int
6940 {
6946 }
6948 static int
6950 {
6952 {
6957 else
6959 " deduced conflicting values for non-type parameter "
6961 }
6963 }
6965 static int
6967 {
6970 " variable-sized array type %qT is not "
6972 arg);
6974 }
6976 static int
6978 {
6982 arg);
6984 }
6986 static int
6988 {
6990 {
6996 else
7001 }
7003 }
7005 static int
7007 {
7009 }
7011 static int
7014 {
7016 }
7018 static int
7021 {
7027 }
7029 static int
7032 {
7035 {
7043 }
7045 }
7047 static int
7049 {
7052 " template parameters of a template template argument are "
7055 }
7057 static int
7059 {
7065 }
7067 static int
7069 {
7074 }
7076 /* Subroutine of convert_nontype_argument, to check whether EXPR, as an
7077 argument for TYPE, points to an unsuitable object.
7079 Also adjust the type of the index in C++20 array subobject references. */
7081 static bool
7083 {
7085 {
7086 CASE_CONVERT:
7088 complain);
7092 complain);
7095 {
7099 }
7103 {
7109 {
7113 /* Canonicalize array offsets to ptrdiff_t; how they were
7114 written doesn't matter for subobject identity. */
7117 }
7120 {
7123 "%qE is not a valid template argument of type %qT "
7127 }
7129 {
7132 "%qE is not a valid template argument of type %qT "
7136 }
7139 {
7142 "%qE is not a valid template argument of type %qT "
7145 }
7146 /* C++17: For a non-type template-parameter of reference or pointer
7147 type, the value of the constant expression shall not refer to (or
7148 for a pointer type, shall not be the address of):
7149 * a subobject (4.5),
7150 * a temporary object (15.2),
7151 * a string literal (5.13.5),
7152 * the result of a typeid expression (8.2.8), or
7153 * a predefined __func__ variable (11.4.1). */
7155 {
7158 decl);
7160 }
7162 && !(same_type_ignoring_top_level_qualifiers_p
7165 {
7170 }
7172 {
7176 decl);
7178 }
7179 }
7187 else
7188 {
7190 {
7193 "because %qD is a variable, not the address of "
7196 }
7197 else
7198 {
7204 }
7205 }
7206 }
7209 }
7211 /* Return a VAR_DECL for the C++20 template parameter object corresponding to
7212 template argument EXPR. */
7214 static tree
7216 {
7221 {
7226 }
7230 /* This is no longer a compound literal. */
7234 }
7236 /* The template arguments corresponding to template parameter objects of types
7237 that contain pointers to members. */
7241 /* Find or build an nttp object for (already-validated) EXPR with name
7242 NAME. */
7244 tree
7246 {
7263 {
7264 /* If EXPR contains any PTRMEM_CST, they will get clobbered by
7265 lower_var_init before we're done mangling. So store the original
7266 value elsewhere. */
7269 }
7274 }
7276 /* Return the actual template argument corresponding to template parameter
7277 object VAR. */
7279 tree
7281 {
7285 }
7287 /* Attempt to convert the non-type template parameter EXPR to the
7288 indicated TYPE. If the conversion is successful, return the
7289 converted value. If the conversion is unsuccessful, return
7290 NULL_TREE if we issued an error message, or error_mark_node if we
7291 did not. We issue error messages for out-and-out bad template
7292 parameters, but not simply because the conversion failed, since we
7293 might be just trying to do argument deduction. Both TYPE and EXPR
7294 must be non-dependent.
7296 The conversion follows the special rules described in
7297 [temp.arg.nontype], and it is much more strict than an implicit
7298 conversion.
7300 This function is called twice for each template argument (see
7301 lookup_template_class for a more accurate description of this
7302 problem). This means that we need to handle expressions which
7303 are not valid in a C++ source, but can be created from the
7304 first call (for instance, casts to perform conversions). These
7305 hacks can go away after we fix the double coercion problem. */
7307 static tree
7309 {
7310 tree expr_type;
7313 /* Detect immediately string literals as invalid non-type argument.
7314 This special-case is not needed for correctness (we would easily
7315 catch this later), but only to provide better diagnostic for this
7316 common user mistake. As suggested by DR 100, we do not mention
7317 linkage issues in the diagnostic as this is not the point. */
7319 {
7325 }
7327 /* Add the ADDR_EXPR now for the benefit of
7328 value_dependent_expression_p. */
7331 {
7335 }
7337 /* If we are in a template, EXPR may be non-dependent, but still
7338 have a syntactic, rather than semantic, form. For example, EXPR
7339 might be a SCOPE_REF, rather than the VAR_DECL to which the
7340 SCOPE_REF refers. Preserving the qualifying scope is necessary
7341 so that access checking can be performed when the template is
7342 instantiated -- but here we need the resolved form so that we can
7343 convert the argument. */
7355 /* If the argument is non-dependent, perform any conversions in
7356 non-dependent context as well. */
7364 else
7367 /* 14.3.2/5: The null pointer{,-to-member} conversion is applied
7368 to a non-type argument of "nullptr". */
7372 /* In C++11, integral or enumeration non-type template arguments can be
7373 arbitrary constant expressions. Pointer and pointer to
7374 member arguments can be general constant expressions that evaluate
7375 to a null value, but otherwise still need to be of a specific form. */
7377 {
7379 /* A PTRMEM_CST is already constant, and a valid template
7380 argument for a parameter of pointer to member type, we just want
7381 to leave it in that form rather than lower it to a
7385 {
7386 /* C++17: A template-argument for a non-type template-parameter shall
7387 be a converted constant expression (8.20) of the type of the
7388 template-parameter. */
7391 /* Make sure we return NULL_TREE only if we have really issued
7392 an error, as described above. */
7395 {
7398 }
7401 /* EXPR may have become value-dependent. */
7403 }
7405 {
7410 }
7411 }
7415 else
7418 /* HACK: Due to double coercion, we can get a
7419 NOP_EXPR<REFERENCE_TYPE>(ADDR_EXPR<POINTER_TYPE> (arg)) here,
7420 which is the tree that we built on the first call (see
7421 below when coercing to reference to object or to reference to
7422 function). We just strip everything and get to the arg.
7423 See g++.old-deja/g++.oliva/template4.C and g++.dg/template/nontype9.C
7424 for examples. */
7426 {
7427 /* Check this before we strip *& to avoid redundancy. */
7436 {
7437 /* ??? Maybe we could use convert_from_reference here, but we
7438 would need to relax its constraints because the NOP_EXPR
7439 could actually change the type to something more cv-qualified,
7440 and this is not folded by convert_from_reference. */
7445 && (same_type_ignoring_top_level_qualifiers_p
7448 {
7451 }
7452 }
7453 }
7455 /* [temp.arg.nontype]/5, bullet 1
7457 For a non-type template-parameter of integral or enumeration type,
7458 integral promotions (_conv.prom_) and integral conversions
7459 (_conv.integral_) are applied. */
7462 {
7464 {
7469 }
7474 /* Notice that there are constant expressions like '4 % 0' which
7475 do not fold into integer constants. */
7477 {
7479 {
7483 else
7489 /* else cxx_constant_value complained but gave us
7490 a real constant, so go ahead. */
7492 {
7493 /* Some assemble time constant expressions like
7494 (intptr_t)&&lab1 - (intptr_t)&&lab2 or
7495 4 + (intptr_t)&&var satisfy reduced_constant_expression_p
7496 as we can emit them into .rodata initializers of
7497 variables, yet they can't fold into an INTEGER_CST at
7498 compile time. Refuse them here. */
7503 }
7504 }
7505 else
7507 }
7509 /* Avoid typedef problems. */
7512 }
7513 /* [temp.arg.nontype]/5, bullet 2
7515 For a non-type template-parameter of type pointer to object,
7516 qualification conversions (_conv.qual_) and the array-to-pointer
7517 conversion (_conv.array_) are applied. */
7519 {
7522 /* Look through any NOP_EXPRs around an ADDR_EXPR, whether they come from
7523 decay_conversion or an explicit cast. If it's a problematic cast,
7524 we'll complain about it below. */
7526 {
7531 {
7534 }
7535 }
7537 /* [temp.arg.nontype]/1 (TC1 version, DR 49):
7539 A template-argument for a non-type, non-template template-parameter
7540 shall be one of: [...]
7542 -- the name of a non-type template-parameter;
7543 -- the address of an object or function with external linkage, [...]
7544 expressed as "& id-expression" where the & is optional if the name
7545 refers to a function or array, or if the corresponding
7546 template-parameter is a reference.
7548 Here, we do not care about functions, as they are invalid anyway
7549 for a parameter of type pointer-to-object. */
7552 /* Non-type template parameters are OK. */
7553 ;
7558 /* Other values, like integer constants, might be valid
7559 non-type arguments of some other type. */
7569 }
7570 /* [temp.arg.nontype]/5, bullet 3
7572 For a non-type template-parameter of type reference to object, no
7573 conversions apply. The type referred to by the reference may be more
7574 cv-qualified than the (otherwise identical) type of the
7575 template-argument. The template-parameter is bound directly to the
7576 template-argument, which must be an lvalue. */
7578 {
7580 expr_type))
7584 {
7589 }
7592 {
7597 }
7599 /* [temp.arg.nontype]/1
7601 A template-argument for a non-type, non-template template-parameter
7602 shall be one of: [...]
7604 -- the address of an object or function with external linkage. */
7607 {
7610 {
7613 "because a reference variable does not have a constant "
7616 }
7617 }
7620 /* OK, dependent reference. We don't want to ask whether a DECL is
7622 else
7623 {
7628 }
7632 }
7633 /* [temp.arg.nontype]/5, bullet 4
7635 For a non-type template-parameter of type pointer to function, only
7636 the function-to-pointer conversion (_conv.func_) is applied. If the
7637 template-argument represents a set of overloaded functions (or a
7638 pointer to such), the matching function is selected from the set
7639 (_over.over_). */
7641 {
7642 /* If the argument is a template-id, we might not have enough
7643 context information to decay the pointer. */
7645 {
7649 }
7652 /* Null pointer values are OK in C++11. */
7658 }
7659 /* [temp.arg.nontype]/5, bullet 5
7661 For a non-type template-parameter of type reference to function, no
7662 conversions apply. If the template-argument represents a set of
7663 overloaded functions, the matching function is selected from the set
7664 (_over.over_). */
7666 {
7668 {
7670 {
7675 }
7677 }
7682 }
7683 /* [temp.arg.nontype]/5, bullet 6
7685 For a non-type template-parameter of type pointer to member function,
7686 no conversions apply. If the template-argument represents a set of
7687 overloaded member functions, the matching member function is selected
7688 from the set (_over.over_). */
7690 {
7695 /* [temp.arg.nontype] bullet 1 says the pointer to member
7696 expression must be a pointer-to-member constant. */
7701 /* Repeated conversion can't deal with a conversion that turns PTRMEM_CST
7702 into a CONSTRUCTOR, so build up a new PTRMEM_CST instead. */
7705 }
7706 /* [temp.arg.nontype]/5, bullet 7
7708 For a non-type template-parameter of type pointer to data member,
7709 qualification conversions (_conv.qual_) are applied. */
7711 {
7712 /* [temp.arg.nontype] bullet 1 says the pointer to member
7713 expression must be a pointer-to-member constant. */
7721 }
7723 {
7725 {
7730 }
7732 }
7734 {
7735 /* Replace the argument with a reference to the corresponding template
7736 parameter object. */
7741 }
7742 /* A template non-type parameter must be one of the above. */
7743 else
7746 /* Sanity check: did we actually convert the argument to the
7747 right type? */
7751 }
7753 /* Subroutine of coerce_template_template_parms, which returns 1 if
7754 PARM_PARM and ARG_PARM match using the rule for the template
7755 parameters of template template parameters. Both PARM and ARG are
7756 template parameters; the rest of the arguments are the same as for
7757 coerce_template_template_parms.
7758 */
7759 static int
7761 tree arg,
7762 tsubst_flags_t complain,
7763 tree in_decl,
7764 tree outer_args)
7765 {
7774 {
7776 /* We encounter instantiations of templates like
7777 template <template <template <class> class> class TT>
7778 class C; */
7779 {
7783 }
7784 /* Fall through. */
7789 /* Argument is a parameter pack but parameter is not. */
7794 /* The tsubst call is used to handle cases such as
7796 template <int> class C {};
7797 template <class T, template <T> class TT> class D {};
7798 D<int, C> d;
7800 i.e. the parameter list of TT depends on earlier parameters. */
7802 {
7807 }
7811 /* Argument is a parameter pack but parameter is not. */
7818 }
7821 }
7823 /* Coerce template argument list ARGLIST for use with template
7824 template-parameter TEMPL. */
7826 static tree
7828 tsubst_flags_t complain)
7829 {
7830 /* Consider an example where a template template parameter declared as
7832 template <class T, class U = std::allocator<T> > class TT
7834 The template parameter level of T and U are one level larger than
7835 of TT. To proper process the default argument of U, say when an
7836 instantiation `TT<int>' is seen, we need to build the full
7837 arguments containing {int} as the innermost level. Outer levels,
7838 available when not appearing as default template argument, can be
7839 obtained from the arguments of the enclosing template.
7841 Suppose that TT is later substituted with std::vector. The above
7842 instantiation is `TT<int, std::allocator<T> >' with TT at
7843 level 1, and T at level 2, while the template arguments at level 1
7844 becomes {std::vector} and the inner level 2 is {int}. */
7850 {
7851 /* This is an argument of the current template, so we haven't set
7852 DECL_CONTEXT yet. We can also get here when level-lowering a
7853 bound ttp. */
7854 tree relevant_template_parms;
7856 /* Parameter levels that are greater than the level of the given
7857 template template parm are irrelevant. */
7864 }
7871 }
7873 /* A cache of template template parameters with match-all default
7874 arguments. */
7877 /* T is a bound template template-parameter. Copy its arguments into default
7878 arguments of the template template-parameter's template parameters. */
7880 static tree
7882 {
7905 {
7908 {
7911 }
7912 }
7916 tree gen_ntmpl;
7919 else
7929 }
7931 /* ARG is a bound potential template template-argument, and PARGS is a list
7932 of arguments for the corresponding template template-parameter. Adjust
7933 PARGS as appropriate for application to ARG's template, and if ARG is a
7934 BOUND_TEMPLATE_TEMPLATE_PARM, possibly adjust it to add default template
7935 arguments to the template template parameter. */
7937 static tree
7939 {
7943 {
7944 /* When comparing two template template-parameters in partial ordering,
7945 rewrite the one currently being used as an argument to have default
7946 arguments for all parameters. */
7952 }
7953 else
7954 {
7955 tree aparms
7958 }
7961 }
7963 /* Subroutine of unify for the case when PARM is a
7964 BOUND_TEMPLATE_TEMPLATE_PARM. */
7966 static int
7969 {
7973 /* The template template parm might be variadic and the argument
7974 not, so flatten both argument lists. */
7979 {
7980 /* In keeping with P0522R0, adjust P's template arguments
7981 to apply to A's template; then flatten it again. */
7989 /* If the P0522 adjustment eliminated a pack expansion, deduce
7990 empty packs. */
7996 }
7997 else
7998 {
7999 /* Deduce arguments T, i from TT<T> or TT<i>.
8000 We check each element of PARMVEC and ARGVEC individually
8001 rather than the whole TREE_VEC since they can have
8002 different number of elements, which is allowed under N2555. */
8006 /* Check if the parameters end in a pack, making them
8007 variadic. */
8014 /* If the template argument list of P contains a pack
8015 expansion that is not the last template argument, the
8016 entire template argument list is a non-deduced
8017 context. */
8035 DEDUCE_EXACT,
8038 }
8041 }
8043 /* Return 1 if PARM_TMPL and ARG_TMPL match using rule for
8044 template template parameters.
8046 Consider the example:
8047 template <class T> class A;
8048 template<template <class U> class TT> class B;
8050 For B<A>, PARM_TMPL is TT, while ARG_TMPL is A,
8051 and OUTER_ARGS contains A. */
8053 static int
8055 tree arg_tmpl,
8056 tsubst_flags_t complain,
8057 tree in_decl,
8058 tree outer_args)
8059 {
8073 {
8074 /* P0522R0: A template template-parameter P is at least as specialized as
8075 a template template-argument A if, given the following rewrite to two
8076 function templates, the function template corresponding to P is at
8077 least as specialized as the function template corresponding to A
8078 according to the partial ordering rules for function templates
8079 ([temp.func.order]). Given an invented class template X with the
8080 template parameter list of A (including default arguments):
8082 * Each of the two function templates has the same template parameters,
8083 respectively, as P or A.
8085 * Each function template has a single function parameter whose type is
8086 a specialization of X with template arguments corresponding to the
8087 template parameters from the respective function template where, for
8088 each template parameter PP in the template parameter list of the
8089 function template, a corresponding template argument AA is formed. If
8090 PP declares a parameter pack, then AA is the pack expansion
8091 PP... ([temp.variadic]); otherwise, AA is the id-expression PP.
8093 If the rewrite produces an invalid type, then P is not at least as
8094 specialized as A. */
8096 /* So coerce P's args to apply to A's parms, and then deduce between A's
8097 args and the converted args. If that succeeds, A is at least as
8098 specialized as P, so they match.*/
8104 /* PARM and ARG might be at different template depths, and we want to
8105 pass the right additional levels of args when coercing PARGS to
8106 ARG_PARMS in case we need to do any substitution into non-type
8107 template parameter types.
8109 OUTER_ARGS are not the right outer levels in this case, as they are
8110 the args we're building up for PARM, and for the coercion we want the
8111 args for ARG. If DECL_CONTEXT isn't set for a template template
8112 parameter, we can assume that it's in the current scope. */
8120 {
8125 /* Only use as many levels from the scope as needed
8126 (excluding the level of ARG). */
8130 else
8133 /* Add the arguments that appear at the levels of ARG. */
8140 }
8141 else
8147 {
8153 }
8154 }
8156 /* Determine whether we have a parameter pack at the end of the
8157 template template parameter's template parameter list. */
8159 {
8166 {
8180 }
8181 }
8187 /* Check all of the template parameters except the parameter pack at
8188 the end (if any). */
8190 {
8199 outer_args))
8202 }
8205 {
8206 /* Check each of the template parameters in the template
8207 argument against the template parameter pack at the end of
8208 the template template parameter. */
8215 {
8222 outer_args))
8224 }
8225 }
8228 }
8230 /* Verifies that the deduced template arguments (in TARGS) for the
8231 template template parameters (in TPARMS) represent valid bindings,
8232 by comparing the template parameter list of each template argument
8233 to the template parameter list of its corresponding template
8234 template parameter, in accordance with DR150. This
8235 routine can only be called after all template arguments have been
8236 deduced. It will return TRUE if all of the template template
8237 parameter bindings are okay, FALSE otherwise. */
8238 bool
8240 {
8244 /* We're dealing with template parms in this process. */
8250 {
8255 {
8260 {
8261 /* Look inside the argument pack. */
8264 }
8267 {
8269 /* Extract the next argument from the argument
8270 pack. */
8274 /* Look at the pattern of the pack expansion. */
8277 /* Extract the template parameters from the template
8278 argument. */
8282 /* Verify that we can coerce the template template
8283 parameters from the template argument to the template
8284 parameter. This requires an exact match. */
8286 && !coerce_template_template_parms
8288 targ,
8289 tf_none,
8290 tparm,
8291 targs))
8292 {
8295 }
8296 }
8297 }
8298 }
8300 out:
8304 }
8306 /* Since type attributes aren't mangled, we need to strip them from
8307 template type arguments. */
8309 tree
8311 {
8321 }
8323 /* And from inside dependent non-type arguments like sizeof(Type). */
8325 static tree
8327 {
8337 }
8339 /* A template declaration can be substituted for a constrained
8340 template template parameter only when the argument is no more
8341 constrained than the parameter. */
8343 static bool
8345 {
8348 /* For now, allow constrained template template arguments
8349 and unconstrained template template parameters. */
8353 /* If the template parameter is constrained, we need to rewrite its
8354 constraints in terms of the ARG's template parameters. This ensures
8355 that all of the template parameter types will have the same depth.
8357 Note that this is only valid when coerce_template_template_parm is
8358 true for the innermost template parameters of PARM and ARG. In other
8359 words, because coercion is successful, this conversion will be valid. */
8362 {
8372 }
8375 }
8377 // Convert a placeholder argument into a binding to the original
8378 // parameter. The original parameter is saved as the TREE_TYPE of
8379 // ARG.
8382 {
8385 }
8387 /* We can't fully resolve ARG given as a non-type template argument to TYPE,
8388 because one of them is dependent. But we need to represent the
8389 conversion for the benefit of cp_tree_equal. */
8391 static tree
8393 {
8394 /* Auto parms get no conversion. */
8397 /* We don't need or want to add this conversion now if we're going to use the
8398 argument for deduction. */
8410 }
8412 /* Convert the indicated template ARG as necessary to match the
8413 indicated template PARM. Returns the converted ARG, or
8414 error_mark_node if the conversion was unsuccessful. Error and
8415 warning messages are issued under control of COMPLAIN. This
8416 conversion is for the Ith parameter in the parameter list. ARGS is
8417 the full set of template arguments deduced so far. */
8419 static tree
8421 tree arg,
8422 tree args,
8423 tsubst_flags_t complain,
8425 tree in_decl)
8426 {
8427 tree orig_arg;
8428 tree val;
8434 /* Trivially convert placeholders. */
8443 {
8444 /* The template argument was the name of some
8445 member function. That's usually
8446 invalid, but static members are OK. In any
8447 case, grab the underlying fields/functions
8448 and issue an error later if required. */
8450 }
8458 /* When determining whether an argument pack expansion is a template,
8459 look at the pattern. */
8463 /* Deal with an injected-class-name used as a template template arg. */
8465 {
8468 {
8478 }
8479 }
8481 is_tmpl_type =
8497 {
8499 {
8503 }
8506 "to refer to a type member of a template parameter, "
8511 typename_type,
8512 complain);
8515 }
8517 {
8519 {
8521 {
8526 {
8527 /* The template argument is a type, but we're expecting
8528 an expression. */
8533 /* [temp.arg]/2: "In a template-argument, an ambiguity
8534 between a type-id and an expression is resolved to a
8535 type-id, regardless of the form of the corresponding
8536 template-parameter." So give the user a clue. */
8539 "for non-type template parameter is treated as "
8541 }
8545 else
8548 }
8549 }
8551 }
8553 {
8555 {
8562 else
8565 }
8567 }
8570 /* We already did the appropriate conversion when packing args. */
8573 {
8575 {
8577 /* The number of argument required is not known yet.
8578 Just accept it for now. */
8580 else
8581 {
8582 /* Strip alias templates that are equivalent to another
8583 template. */
8588 args))
8589 {
8592 /* TEMPLATE_TEMPLATE_PARM node is preferred over
8593 TEMPLATE_DECL. */
8595 {
8600 }
8601 }
8602 else
8603 {
8605 {
8612 }
8615 }
8617 // Check that the constraints are compatible before allowing the
8618 // substitution.
8621 {
8623 {
8629 }
8631 }
8632 }
8633 }
8634 else
8636 /* We only form one instance of each template specialization.
8637 Therefore, if we use a non-canonical variant (i.e., a
8638 typedef), any future messages referring to the type will use
8639 the typedef, which is confusing if those future uses do not
8640 themselves also use the typedef. */
8643 }
8644 else
8645 {
8650 /* We don't have enough levels of args to do any substitution. This
8653 {
8658 }
8659 else
8662 /* Perform array-to-pointer and function-to-pointer conversion
8663 as per [temp.param]/10. */
8669 /* Drop top-level cv-qualifiers on the substituted/deduced type of
8670 this non-type template parameter, as per [temp.param]/6. */
8678 /* We used to call digest_init here. However, digest_init
8679 will report errors, which we don't want when complain
8680 is zero. More importantly, digest_init will try too
8681 hard to convert things: for example, `0' should not be
8682 converted to pointer type at this point according to
8683 the standard. Accepting this is not merely an
8684 extension, since deciding whether or not these
8685 conversions can occur is part of determining which
8686 function template to call, or whether a given explicit
8687 argument specification is valid. */
8689 else
8690 {
8693 }
8704 {
8705 /* Reject template arguments that are references to built-in
8706 functions with no library fallbacks. */
8715 }
8718 {
8719 /* Strip typedefs from the SCOPE_REF. */
8722 complain);
8725 }
8726 }
8729 }
8731 /* Coerces the remaining template arguments in INNER_ARGS (from
8732 ARG_IDX to the end) into the parameter pack at PARM_IDX in PARMS.
8733 Returns the coerced argument pack. PARM_IDX is the position of this
8734 parameter in the template parameter list. ARGS is the original
8735 template argument list. */
8736 static tree
8739 tree args,
8740 tree inner_args,
8742 tree new_args,
8744 tree in_decl,
8745 tsubst_flags_t complain)
8746 {
8749 tree packed_args;
8750 tree argument_pack;
8757 {
8758 /* When the template parameter is a non-type template parameter pack
8759 or template template parameter pack whose type or template
8760 parameters use parameter packs, we know exactly how many arguments
8761 we are looking for. Build a vector of the instantiated decls for
8762 these template parameters in PACKED_PARMS. */
8763 /* We can't use make_pack_expansion here because it would interpret a
8764 _DECL as a use rather than a declaration. */
8778 /* If we're doing a partial instantiation of a member template,
8779 verify that all of the types used for the non-type
8780 template parameter pack are, in fact, valid for non-type
8781 template parameters. */
8784 {
8787 {
8792 }
8793 /* We don't know how many args we have yet, just
8794 use the unconverted ones for now. */
8796 }
8799 }
8800 /* Check if we have a placeholder pack, which indicates we're
8801 in the context of a introduction list. In that case we want
8802 to match this pack to the single placeholder. */
8806 {
8809 }
8810 else
8813 /* Convert the remaining arguments, which will be a part of the
8814 parameter pack "parm". */
8817 {
8823 {
8824 /* Once we've packed as many args as we have types, stop. */
8828 /* We don't know how many args we have yet, just
8829 use the unconverted ones for now. */
8831 else
8833 }
8836 {
8839 }
8840 else
8843 in_decl);
8847 }
8851 {
8856 }
8861 else
8862 {
8865 }
8872 }
8874 /* Returns the number of pack expansions in the template argument vector
8875 ARGS. */
8877 static int
8879 {
8884 {
8888 }
8890 }
8892 /* Convert all template arguments to their appropriate types, and
8893 return a vector containing the innermost resulting template
8894 arguments. If any error occurs, return error_mark_node. Error and
8895 warning messages are issued under control of COMPLAIN.
8897 If PARMS represents all template parameters levels, this function
8898 returns a vector of vectors representing all the resulting argument
8899 levels. Note that in this case, only the innermost arguments are
8900 coerced because the outermost ones are supposed to have been coerced
8901 already. Otherwise, if PARMS represents only (the innermost) vector
8902 of parameters, this function returns a vector containing just the
8903 innermost resulting arguments.
8905 If REQUIRE_ALL_ARGS is false, argument deduction will be performed
8906 for arguments not specified in ARGS. If REQUIRE_ALL_ARGS is true,
8907 arguments not specified in ARGS must have default arguments which
8908 we'll use to fill in ARGS. */
8910 tree
8912 tree args,
8913 tree in_decl,
8914 tsubst_flags_t complain,
8916 {
8918 tree orig_inner_args;
8919 tree inner_args;
8921 /* When used as a boolean value, indicates whether this is a
8922 variadic template parameter list. Since it's an int, we can also
8923 subtract it from nparms to get the number of non-variadic
8924 parameters. */
8929 /* Adjustment to nparms for fixed parameter packs. */
8934 /* Likewise for parameters with default arguments. */
8942 {
8944 {
8947 }
8949 }
8953 /* Determine if there are any parameter packs or default arguments. */
8955 {
8963 }
8966 /* If there are no parameters that follow a parameter pack, we need to
8967 expand any argument packs so that we can deduce a parameter pack from
8968 some non-packed args followed by an argument pack, as in variadic85.C.
8969 If there are such parameters, we need to leave argument packs intact
8970 so the arguments are assigned properly. This can happen when dealing
8971 with a nested class inside a partial specialization of a class
8972 template, as in variadic92.C, or when deducing a template parameter pack
8973 from a sub-declarator, as in variadic114.C. */
8977 /* Count any pack expansion args. */
8983 && require_all_args
8984 && !variadic_args_p
8987 {
8988 bad_nargs:
8990 {
8992 {
8996 }
8997 else
9004 }
9007 }
9008 /* We can't pass a pack expansion to a non-pack parameter of an alias
9009 template (DR 1430). */
9013 && variadic_args_p
9015 {
9017 {
9019 {
9025 {
9028 "pack expansion argument for non-pack parameter "
9030 else
9032 "pack expansion argument for non-pack parameter "
9036 }
9037 }
9039 found:;
9040 }
9042 }
9044 /* We need to evaluate the template arguments, even though this
9045 template-id may be nested within a "sizeof". */
9046 cp_evaluated ev;
9052 {
9053 tree arg;
9054 tree parm;
9056 /* Get the Ith template parameter. */
9060 {
9063 }
9065 /* Calculate the next argument. */
9068 else
9074 {
9075 /* Some arguments will be placed in the
9076 template parameter pack PARM. */
9083 {
9084 /* We don't know how many args we have yet, just use the
9085 unconverted (and still packed) ones for now. */
9089 }
9093 /* Store this argument. */
9095 {
9096 lost++;
9097 /* We are done with all of the arguments. */
9100 }
9101 else
9102 {
9106 {
9109 }
9110 }
9113 }
9115 {
9117 {
9118 /* "If every valid specialization of a variadic template
9119 requires an empty template parameter pack, the template is
9120 ill-formed, no diagnostic required." So check that the
9121 pattern works with this parameter. */
9126 in_decl);
9128 {
9133 }
9135 /* Recover from missing typename. */
9139 /* We don't know how many args we have yet, just
9140 use the unconverted ones for now. */
9144 }
9145 }
9147 {
9148 /* There must be a default arg in this case. */
9151 /* The position of the first default template argument,
9152 is also the number of non-defaulted arguments in NEW_INNER_ARGS.
9153 Record that. */
9157 }
9158 else
9162 {
9165 }
9167 {
9168 /* This can occur if there was an error in the template
9169 parameter list itself (which we would already have
9170 reported) that we are trying to recover from, e.g., a class
9171 template with a parameter list such as
9172 template<typename..., typename> (cpp0x/variadic150.C). */
9175 /* This can also happen with a fixed parameter pack (71834). */
9178 }
9179 else
9185 lost++;
9188 }
9191 {
9192 /* If we had fixed parameter packs, we didn't know how many arguments we
9193 actually needed earlier; now we do. */
9197 }
9200 {
9201 /* We had some pack expansion arguments that will only work if the packs
9202 are empty, but wait until instantiation time to complain.
9203 See variadic-ttp3.C. */
9205 /* Except that we can't provide empty packs to alias templates or
9206 concepts when there are no corresponding parameters. Basically,
9207 we can get here with this:
9209 template<typename T> concept C = true;
9211 template<typename... Args>
9212 requires C<Args...>
9213 void f();
9215 When parsing C<Args...>, we try to form a concept check of
9216 C<?, Args...>. Without the extra check for substituting an empty
9217 pack past the last parameter, we can accept the check as valid.
9219 FIXME: This may be valid for alias templates (but I doubt it).
9221 FIXME: The error could be better also. */
9223 {
9228 }
9239 }
9242 {
9245 }
9252 }
9254 /* Returns true if T is a wrapper to make a C++20 template parameter
9255 object const. */
9257 static bool
9259 {
9265 }
9267 /* Returns 1 if template args OT and NT are equivalent. */
9269 int
9271 {
9284 /* DR 1558: Don't treat an alias template specialization with dependent
9285 arguments as equivalent to its underlying type when used as a template
9286 argument; we need them to be distinct so that we substitute into the
9287 specialization arguments at instantiation time. And aliases can't be
9288 equivalent without being ==, so we don't need to look any deeper.
9290 During partial ordering, however, we need to treat them normally so we can
9291 order uses of the same alias with different cv-qualification (79960). */
9297 /* For member templates */
9310 {
9314 }
9315 else
9316 {
9317 /* Try to treat a template non-type argument that has been converted
9318 to the parameter type as equivalent to one that hasn't yet. */
9332 }
9333 }
9335 /* Returns true iff the OLDARGS and NEWARGS are in fact identical sets of
9336 template arguments. Returns false otherwise, and updates OLDARG_PTR and
9337 NEWARG_PTR with the offending arguments if they are non-NULL. */
9339 bool
9343 {
9354 {
9359 {
9365 }
9366 }
9368 }
9372 {
9374 }
9376 /* Implement a freelist interface for objects of type T.
9378 Head is a separate object, rather than a regular member, so that we
9379 can define it as a GTY deletable pointer, which is highly
9380 desirable. A data member could be declared that way, but then the
9381 containing object would implicitly get GTY((user)), which would
9382 prevent us from instantiating freelists as global objects.
9383 Although this way we can create freelist global objects, they're
9384 such thin wrappers that instantiating temporaries at every use
9385 loses nothing and saves permanent storage for the freelist object.
9387 Member functions next, anew, poison and reinit have default
9388 implementations that work for most of the types we're interested
9389 in, but if they don't work for some type, they should be explicitly
9390 specialized. See the comments before them for requirements, and
9391 the example specializations for the tree_list_freelist. */
9393 class freelist
9394 {
9395 /* Return the next object in a chain. We could just do type
9396 punning, but if we access the object with its underlying type, we
9397 avoid strict-aliasing trouble. This needs only work between
9398 poison and reinit. */
9401 /* Return a newly allocated, uninitialized or minimally-initialized
9402 object of type T. Any initialization performed by anew should
9403 either remain across the life of the object and the execution of
9404 poison, or be redone by reinit. */
9407 /* Optionally scribble all over the bits holding the object, so that
9408 they become (mostly?) uninitialized memory. This is called while
9409 preparing to make the object part of the free list. */
9414 #ifdef ENABLE_GC_CHECKING
9415 /* Poison the data, to indicate the data is garbage. */
9418 #endif
9419 /* Let valgrind know the object is free. */
9422 /* Let valgrind know the next portion of the object is available,
9423 but uninitialized. */
9425 }
9427 /* Bring an object that underwent at least one lifecycle after anew
9428 and before the most recent free and poison, back to a usable
9429 state, reinitializing whatever is needed for it to be
9430 functionally equivalent to an object just allocated and returned
9431 by anew. This may poison or clear the next field, used by
9432 freelist housekeeping after poison was called. */
9436 #ifdef ENABLE_GC_CHECKING
9438 #endif
9439 /* Let valgrind know the entire object is available, but
9440 uninitialized. */
9442 }
9444 /* Reference a GTY-deletable pointer that points to the first object
9445 in the free list proper. */
9448 /* Construct a freelist object chaining objects off of HEAD. */
9451 /* Add OBJ to the free object list. The former head becomes OBJ's
9452 successor. */
9454 {
9458 }
9460 /* Take an object from the free list, if one is available, or
9461 allocate a new one. Objects taken from the free list should be
9462 regarded as filled with garbage, except for bits that are
9463 configured to be preserved across free and alloc. */
9465 {
9467 {
9472 }
9473 else
9475 }
9476 };
9478 /* Explicitly specialize the interfaces for freelist<tree_node>: we
9479 want to allocate a TREE_LIST using the usual interface, and ensure
9480 TREE_CHAIN remains functional. Alas, we have to duplicate a bit of
9481 build_tree_list logic in reinit, so this could go out of sync. */
9485 {
9487 }
9489 inline tree
9491 {
9493 }
9497 {
9503 #ifdef ENABLE_GC_CHECKING
9506 /* Poison the data, to indicate the data is garbage. */
9509 #endif
9510 /* Let valgrind know the object is free. */
9512 /* But we still want to use the TREE_CODE and TREE_CHAIN parts. */
9516 #ifdef ENABLE_GC_CHECKING
9518 /* Keep TREE_CHAIN functional. */
9520 #else
9522 #endif
9523 }
9527 {
9530 #ifdef ENABLE_GC_CHECKING
9534 #endif
9536 /* Let valgrind know the entire object is available, but
9537 uninitialized. */
9540 #ifdef ENABLE_GC_CHECKING
9542 #else
9544 #endif
9545 }
9547 /* Point to the first object in the TREE_LIST freelist. */
9549 /* Return the/an actual TREE_LIST freelist. */
9552 {
9554 }
9556 /* Point to the first object in the tinst_level freelist. */
9558 /* Return the/an actual tinst_level freelist. */
9561 {
9563 }
9565 /* Point to the first object in the pending_template freelist. */
9567 /* Return the/an actual pending_template freelist. */
9570 {
9572 }
9574 /* Build the TREE_LIST object out of a split list, store it
9575 permanently, and return it. */
9576 tree
9578 {
9587 }
9591 /* Increment OBJ's refcount unless it is already infinite. */
9594 {
9598 }
9600 /* Release storage for OBJ and node, if it's a TREE_LIST. */
9601 void
9603 {
9607 }
9609 /* Decrement OBJ's refcount if not infinite. If it reaches zero, release
9610 OBJ's DECL and OBJ, and start over with the tinst_level object that
9611 used to be referenced by OBJ's NEXT. */
9612 static void
9614 {
9618 {
9622 }
9623 }
9625 /* Modify PTR so that it points to OBJ, adjusting the refcounts of OBJ
9626 and of the former PTR. Omitting the second argument is equivalent
9627 to passing (T*)NULL; this is allowed because passing the
9628 zero-valued integral constant NULL confuses type deduction and/or
9629 overload resolution. */
9631 static void
9633 {
9637 }
9639 static void
9641 {
9651 /* We are called both from instantiate_decl, where we've already had a
9652 tinst_level pushed, and instantiate_template, where we haven't.
9653 Compensate. */
9655 level = !current_tinst_level
9667 else
9676 }
9679 /* Return a TEMPLATE_ID_EXPR corresponding to the indicated FNS and
9680 ARGLIST. Valid choices for FNS are given in the cp-tree.def
9681 documentation for TEMPLATE_ID_EXPR. */
9683 tree
9685 {
9692 {
9695 }
9698 {
9701 unknown_type_node,
9703 arglist);
9705 }
9708 }
9710 /* Within the scope of a template class S<T>, the name S gets bound
9711 (in build_self_reference) to a TYPE_DECL for the class, not a
9712 TEMPLATE_DECL. If DECL is a TYPE_DECL for current_class_type,
9713 or one of its enclosing classes, and that type is a template,
9714 return the associated TEMPLATE_DECL. Otherwise, the original
9715 DECL is returned.
9717 Also handle the case when DECL is a TREE_LIST of ambiguous
9718 injected-class-names from different bases. */
9720 tree
9722 {
9726 /* DR 176: A lookup that finds an injected-class-name (10.2
9727 [class.member.lookup]) can result in an ambiguity in certain cases
9728 (for example, if it is found in more than one base class). If all of
9729 the injected-class-names that are found refer to specializations of
9730 the same class template, and if the name is followed by a
9731 template-argument-list, the reference refers to the class template
9732 itself and not a specialization thereof, and is not ambiguous. */
9734 {
9737 {
9743 }
9746 else
9748 }
9754 }
9756 /* Given an IDENTIFIER_NODE (or type TEMPLATE_DECL) and a chain of
9757 parameters, find the desired type.
9759 D1 is the PTYPENAME terminal, and ARGLIST is the list of arguments.
9761 IN_DECL, if non-NULL, is the template declaration we are trying to
9762 instantiate.
9764 If ENTERING_SCOPE is nonzero, we are about to enter the scope of
9765 the class we are looking up.
9767 Issue error and warning messages under control of COMPLAIN.
9769 If the template class is really a local class in a template
9770 function, then the FUNCTION_CONTEXT is the function in which it is
9771 being instantiated.
9773 ??? Note that this function is currently called *twice* for each
9774 template-id: the first time from the parser, while creating the
9775 incomplete type (finish_template_type), and the second type during the
9776 real instantiation (instantiate_template_class). This is surely something
9777 that we want to avoid. It also causes some problems with argument
9778 coercion (see convert_nontype_argument for more information on this). */
9780 tree
9783 {
9787 tree t;
9790 spec_entry elt;
9791 hashval_t hash;
9794 {
9798 else
9799 {
9806 }
9807 }
9809 {
9812 /* If we are declaring a constructor, say A<T>::A<T>, we will get
9813 an implicit typename for the second A. Deal with it. */
9818 {
9821 }
9822 }
9825 {
9828 }
9830 {
9833 }
9835 {
9838 }
9840 /* Issue an error message if we didn't find a template. */
9842 {
9846 }
9849 /* Make sure it's a user visible template, if it was named by
9850 the user. */
9853 {
9855 {
9859 }
9861 }
9865 /* An alias that just changes the name of a template is equivalent to the
9866 other template, so if any of the arguments are pack expansions, strip
9867 the alias to avoid problems with a pack expansion passed to a non-pack
9868 alias template parameter (DR 1430). */
9873 {
9874 tree parm;
9883 }
9884 else
9885 {
9887 tree gen_tmpl;
9888 tree type_decl;
9896 /* An error occurred while building the template TEMPL, and a
9897 diagnostic has most certainly been emitted for that
9898 already. Let's propagate that error. */
9910 {
9911 /* We've been given an incomplete set of template arguments.
9912 For example, given:
9914 template <class T> struct S1 {
9915 template <class U> struct S2 {};
9916 template <class U> struct S2<U*> {};
9917 };
9919 we will be called with an ARGLIST of `U*', but the
9920 TEMPLATE will be `template <class T> template
9921 <class U> struct S1<T>::S2'. We must fill in the missing
9922 arguments. */
9926 }
9928 /* Now we should have enough arguments. */
9931 /* From here on, we're only interested in the most general
9932 template. */
9934 /* Shortcut looking up the current class scope again. */
9938 {
9949 }
9951 /* Calculate the BOUND_ARGS. These will be the args that are
9952 actually tsubst'd into the definition to create the
9953 instantiation. */
9958 /* We were unable to bind the arguments. */
9961 /* In the scope of a template class, explicit references to the
9962 template class refer to the type of the template, not any
9963 instantiation of it. For example, in:
9965 template <class T> class C { void f(C<T>); }
9967 the `C<T>' is just the same as `C'. Outside of the
9968 class, however, such a reference is an instantiation. */
9972 {
9977 }
9979 /* If we already have this specialization, return it. */
9989 /* If the template's constraints are not satisfied,
9990 then we cannot form a valid type.
9992 Note that the check is deferred until after the hash
9993 lookup. This prevents redundant checks on previously
9994 instantiated specializations. */
9998 {
10000 {
10001 auto_diagnostic_group d;
10004 }
10006 }
10010 /* If the deduced arguments are invalid, then the binding
10011 failed. */
10015 complain))
10022 /* This occurs when the user has tried to define a tagged type
10023 in a scope that forbids it. We emitted an error during the
10024 parse. We didn't complete the bail out then, so here we
10025 are. */
10030 {
10032 /* If the context of the partially instantiated template is
10033 already non-dependent, then we might as well use it. */
10035 else
10036 {
10039 /* Try completing the enclosing context if it's not already so. */
10042 {
10045 {
10046 /* Completion could have caused us to register the desired
10047 specialization already, so check the table again. */
10051 }
10052 }
10053 }
10054 }
10055 else
10064 /* Create the type. */
10066 {
10067 /* The user referred to a specialization of an alias
10068 template represented by GEN_TMPL.
10070 [temp.alias]/2 says:
10072 When a template-id refers to the specialization of an
10073 alias template, it is equivalent to the associated
10074 type obtained by substitution of its
10075 template-arguments for the template-parameters in the
10076 type-id of the alias template. */
10079 /* Note that the call above (by indirectly calling
10080 register_specialization in tsubst_decl) registers the
10081 TYPE_DECL representing the specialization of the alias
10082 template. So next time someone substitutes ARGLIST for
10083 the template parms into the alias template (GEN_TMPL),
10084 she'll get that TYPE_DECL back. */
10088 }
10090 {
10092 {
10103 }
10104 else
10105 {
10106 /* We don't want to call start_enum for this type, since
10107 the values for the enumeration constants may involve
10108 template parameters. And, no one should be interested
10109 in the enumeration constants for such a type. */
10112 }
10116 }
10118 {
10119 /* Lambda closures are regenerated in tsubst_lambda_expr, not
10120 instantiated here. */
10128 /* A local class. Make sure the decl gets registered properly. */
10135 /* This instantiation is another name for the primary
10136 template type. Set the TYPE_CANONICAL field
10137 appropriately. */
10141 }
10142 else
10145 /* If we called start_enum or pushtag above, this information
10146 will already be set up. */
10149 {
10156 }
10159 /* Although GEN_TMPL is the TEMPLATE_DECL, it has the same value
10160 of export flag. We want to propagate this because it might
10161 be a friend declaration that pushes a new hidden binding. */
10165 {
10171 {
10174 }
10175 }
10179 {
10183 {
10184 tree attributes
10192 }
10193 }
10195 /* Let's consider the explicit specialization of a member
10196 of a class template specialization that is implicitly instantiated,
10197 e.g.:
10198 template<class T>
10199 struct S
10200 {
10201 template<class U> struct M {}; //#0
10202 };
10204 template<>
10205 template<>
10206 struct S<int>::M<char> //#1
10207 {
10208 int i;
10209 };
10210 [temp.expl.spec]/4 says this is valid.
10212 In this case, when we write:
10213 S<int>::M<char> m;
10215 M is instantiated from the CLASSTYPE_TI_TEMPLATE of #1, not from
10216 the one of #0.
10218 When we encounter #1, we want to store the partial instantiation
10219 of M (template<class T> S<int>::M<T>) in its CLASSTYPE_TI_TEMPLATE.
10221 For all cases other than this "explicit specialization of member of a
10222 class template", we just want to store the most general template into
10223 the CLASSTYPE_TI_TEMPLATE of M.
10225 This case of "explicit specialization of member of a class template"
10226 only happens when:
10227 1/ the enclosing class is an instantiation of, and therefore not
10228 the same as, the context of the most general template, and
10229 2/ we aren't looking at the partial instantiation itself, i.e.
10230 the innermost arguments are not the same as the innermost parms of
10231 the most general template.
10233 So it's only when 1/ and 2/ happens that we want to use the partial
10234 instantiation of the member template in lieu of its most general
10235 template. */
10239 /* the enclosing class must be an instantiation... */
10242 {
10246 tree partial_inst_args =
10253 use_partial_inst_tmpl =
10254 /*...and we must not be looking at the partial instantiation
10255 itself. */
10257 partial_inst_args);
10258 }
10261 /* This case is easy; there are no member templates involved. */
10263 else
10264 {
10265 /* This is a full instantiation of a member template. Find
10266 the partial instantiation of which this is an instance. */
10268 /* Temporarily reduce by one the number of levels in the ARGLIST
10269 so as to avoid comparing the last set of arguments. */
10271 /* We don't use COMPLAIN in the following call because this isn't
10272 the immediate context of deduction. For instance, tf_partial
10273 could be set here as we might be at the beginning of template
10274 argument deduction when any explicitly specified template
10275 arguments are substituted into the function type. tf_partial
10276 could lead into trouble because we wouldn't find the partial
10277 instantiation that might have been created outside tf_partial
10278 context, because the levels of template parameters wouldn't
10279 match, because in a tf_partial context, tsubst doesn't reduce
10280 TEMPLATE_PARM_LEVEL. */
10283 /* FOUND is either a proper class type, or an alias
10284 template specialization. In the later case, it's a
10285 TYPE_DECL, resulting from the substituting of arguments
10286 for parameters in the TYPE_DECL of the alias template
10287 done earlier. So be careful while getting the template
10288 of FOUND. */
10290 ? found
10297 {
10298 /* If this partial instantiation is specialized, we want to
10299 use it for hash table lookup. */
10303 }
10304 }
10306 /* Build template info for the new specialization. */
10316 /* Note this use of the partial instantiation so we can check it
10317 later in maybe_process_partial_specialization. */
10325 /* Now that the type has been registered on the instantiations
10326 list, we set up the enumerators. Because the enumeration
10327 constants may involve the enumeration type itself, we make
10328 sure to register the type first, and then create the
10329 constants. That way, doing tsubst_expr for the enumeration
10330 constants won't result in recursive calls here; we'll find
10331 the instantiation and exit above. */
10335 /* If the type makes use of template parameters, the
10336 code that generates debugging information will crash. */
10339 /* Possibly limit visibility based on template args. */
10346 }
10347 }
10349 /* Return a TEMPLATE_ID_EXPR for the given variable template and ARGLIST. */
10351 tree
10353 {
10364 /* The type of the expression is NULL_TREE since the template-id could refer
10365 to an explicit or partial specialization. */
10367 }
10369 /* Instantiate a variable declaration from a TEMPLATE_ID_EXPR if it's
10370 not dependent. */
10372 tree
10374 {
10378 /* If the template or arguments are dependent, then we
10379 can't resolve the TEMPLATE_ID_EXPR yet. */
10385 {
10387 {
10388 auto_diagnostic_group d;
10391 }
10393 }
10396 }
10398 /* Construct a TEMPLATE_ID_EXPR for the given variable template TEMPL having
10399 TARGS template args, and instantiate it if it's not dependent. */
10401 tree
10403 tsubst_flags_t complain)
10404 {
10411 }
10413 /* If the set of template parameters PARMS contains a template parameter
10414 at the given LEVEL and INDEX, then return this parameter. Otherwise
10415 return NULL_TREE. */
10417 static tree
10419 {
10428 }
10430 /* Return the TREE_LIST for the template parameter from PARMS that positionally
10431 corresponds to the template parameter PARM, or else return NULL_TREE. */
10433 static tree
10435 {
10439 }
10441 /* As above, but pull out the actual parameter. */
10443 static tree
10445 {
10451 /* As in template_parm_to_arg. */
10454 else
10459 }
10460 \f
10461 struct pair_fn_data
10462 {
10463 tree_fn_t fn;
10464 tree_fn_t any_fn;
10466 /* True when we should also visit template parameters that occur in
10467 non-deduced contexts. */
10470 };
10472 /* Called from for_each_template_parm via walk_tree. */
10474 static tree
10476 {
10483 #define WALK_SUBTREE(NODE) \
10484 do \
10485 { \
10486 result = for_each_template_parm (NODE, fn, data, pfd->visited, \
10487 pfd->include_nondeduced_p, \
10488 pfd->any_fn); \
10489 if (result) goto out; \
10490 } \
10491 while (0)
10501 {
10505 /* Fall through. */
10511 else
10521 /* Since we're not going to walk subtrees, we have to do this
10522 explicitly here. */
10524 /* Fall through. */
10527 /* Check the return type. */
10530 /* Check the parameter types. Since default arguments are not
10531 instantiated until they are needed, the TYPE_ARG_TYPES may
10532 contain expressions that involve template parameters. But,
10533 no-one should be looking at them yet. And, once they're
10534 instantiated, they don't contain template parameters, so
10535 there's no point in looking at them then, either. */
10536 {
10537 tree parm;
10542 /* Since we've already handled the TYPE_ARG_TYPES, we don't
10543 want walk_tree walking into them itself. */
10545 }
10548 {
10552 }
10568 {
10571 }
10594 /* Record template parameters such as `T' inside `TT<T>'. */
10596 /* Fall through. */
10608 /* A template template parameter is encountered. */
10612 /* Already substituted template template parameter */
10617 /* A template-id in a TYPENAME_TYPE might be a deduced context after
10618 partial instantiation. */
10625 /* If there's no type, then this thing must be some expression
10626 involving template parameters. */
10636 /* These are non-deduced contexts. */
10658 }
10660 #undef WALK_SUBTREE
10662 /* We didn't find any template parameters we liked. */
10663 out:
10665 }
10667 /* For each TEMPLATE_TYPE_PARM, TEMPLATE_TEMPLATE_PARM,
10668 BOUND_TEMPLATE_TEMPLATE_PARM or TEMPLATE_PARM_INDEX in T,
10669 call FN with the parameter and the DATA.
10670 If FN returns nonzero, the iteration is terminated, and
10671 for_each_template_parm returns 1. Otherwise, the iteration
10672 continues. If FN never returns a nonzero value, the value
10673 returned by for_each_template_parm is 0. If FN is NULL, it is
10674 considered to be the function which always returns 1.
10676 If INCLUDE_NONDEDUCED_P, then this routine will also visit template
10677 parameters that occur in non-deduced contexts. When false, only
10678 visits those template parameters that can be deduced. */
10680 static tree
10684 tree_fn_t any_fn)
10685 {
10687 tree result;
10689 /* Set up. */
10695 /* Walk the tree. (Conceptually, we would like to walk without
10696 duplicates, but for_each_template_parm_r recursively calls
10697 for_each_template_parm, so we would need to reorganize a fair
10698 bit to use walk_tree_without_duplicates, so we keep our own
10699 visited list.) */
10702 else
10705 for_each_template_parm_r,
10709 /* Clean up. */
10711 {
10714 }
10717 }
10719 struct find_template_parameter_info
10720 {
10724 {}
10730 tree ctx_parms;
10737 };
10739 /* Appends the declaration of T to the list in DATA. */
10741 static int
10743 {
10746 /* Template parameters declared within the expression are not part of
10747 the parameter mapping. For example, in this concept:
10749 template<typename T>
10750 concept C = requires { <expr> } -> same_as<int>;
10752 the return specifier same_as<int> declares a new decltype parameter
10753 that must not be part of the parameter mapping. The same is true
10754 for generic lambda parameters, lambda template parameters, etc. */
10762 /* We want the underlying TEMPLATE_TEMPLATE_PARM, not the
10763 BOUND_TEMPLATE_TEMPLATE_PARM itself. */
10766 /* This template parameter might be an argument to a cached dependent
10767 specalization that was formed earlier inside some other template, in
10768 which case the parameter is not among the ones that are in-scope.
10769 Look in CTX_PARMS to find the corresponding in-scope template
10770 parameter, and use it instead. */
10774 /* Arguments like const T yield parameters like const T. This means that
10775 a template-id like X<T, const T> would yield two distinct parameters:
10776 T and const T. Adjust types to their unqualified versions. */
10780 {
10781 /* Append T to PARM_LIST. */
10785 }
10787 /* Verify the parameter we found has a valid index. */
10789 {
10795 }
10798 }
10800 /* Ensure that we recursively examine certain terms that are not normally
10801 visited in for_each_template_parm_r. */
10803 static int
10805 {
10808 #define WALK_SUBTREE(NODE) \
10809 do \
10810 { \
10811 for_each_template_parm (NODE, keep_template_parm, data, \
10812 &ftpi->visited, true, \
10813 any_template_parm_r); \
10814 } \
10815 while (0)
10817 /* A mention of a member alias/typedef is a use of all of its template
10818 arguments, including those from the enclosing class, so we don't use
10819 alias_template_specialization_p here. */
10825 {
10827 /* Type constraints of a placeholder type may contain parameters. */
10834 /* Search through references to variable templates. */
10844 /* If T is a member template that shares template parameters with
10845 ctx_parms, we need to mark all those parameters for mapping.
10846 To that end, it should suffice to just walk the DECL_CONTEXT of
10847 the template (assuming the template is not overly general). */
10852 {
10853 /* Look in the parms and body. */
10857 }
10862 /* The conversion-type-id of a conversion operator may be dependent. */
10873 }
10875 /* Keep walking. */
10877 }
10879 /* Look through T for template parameters. */
10881 tree
10883 {
10886 any_template_parm_r);
10887 }
10889 /* As above, but also recursively look into the default arguments of template
10890 parameters we found. Used for alias CTAD. */
10892 tree
10894 {
10897 /* Since newly found parms are added to the end of the list, we
10898 can just walk it until we reach the end. */
10900 {
10905 }
10907 }
10909 /* True if PARM was found by a previous call to find_in. PARM can be a
10910 TREE_LIST, a DECL_TEMPLATE_PARM_P, or a TEMPLATE_PARM_P. */
10912 bool
10914 {
10919 else
10923 }
10925 /* Returns a list of unique template parameters found within T, where CTX_PARMS
10926 are the template parameters in scope. */
10928 tree
10930 {
10937 }
10939 /* Returns true if T depends on any template parameter. */
10941 bool
10943 {
10947 /* Namespaces can't depend on any template parameters. */
10963 else
10965 }
10967 /* Returns true if T depends on any template parameter with level LEVEL. */
10969 bool
10971 {
10974 }
10976 /* Returns true if the signature of DECL depends on any template parameter from
10977 its enclosing class. */
10979 static bool
10981 {
10985 else
10994 {
10997 {
11002 template_parm_outer_level,
11012 }
11013 }
11017 }
11019 /* Returns true if the constraints of DECL depend on any template parameters
11020 from its enclosing scope. */
11022 bool
11024 {
11031 {
11034 else
11036 }
11042 }
11044 /* Returns TRUE iff INST is an instantiation we don't need to do in an
11045 ill-formed translation unit, i.e. a variable or function that isn't
11046 usable in a constant expression. */
11050 {
11056 }
11058 /* Returns TRUE iff we should refuse to instantiate DECL because it's
11059 neglectable and instantiated from within an erroneous instantiation. */
11061 static bool
11063 {
11069 /* Avoid instantiating members of an ill-formed class. */
11070 bool refuse
11075 {
11080 }
11083 {
11084 /* Don't warn about it not being defined. */
11086 tree clone;
11089 }
11091 }
11099 /* We're starting to instantiate D; record the template instantiation context
11100 at LOC for diagnostics and to restore it later. */
11102 bool
11104 {
11108 {
11109 /* Tell error.cc not to try to instantiate any templates. */
11112 "template instantiation depth exceeds maximum of %d"
11114 max_tinst_depth);
11116 }
11118 /* If the current instantiation caused problems, don't let it instantiate
11119 anything else. Do allow deduction substitution and decls usable in
11120 constant expressions. */
11122 {
11123 /* Avoid no_linkage_errors and unused function (and all other)
11124 warnings for this decl. */
11127 }
11129 /* When not -quiet, dump template instantiations other than functions, since
11130 announce_function will take care of those. */
11152 }
11154 /* We're starting substitution of TMPL<ARGS>; record the template
11155 substitution context for diagnostics and to restore it later. */
11157 bool
11159 {
11161 }
11163 /* We're starting to instantiate D; record INPUT_LOCATION and the
11164 template instantiation context for diagnostics and to restore it
11165 later. */
11167 bool
11169 {
11171 }
11173 /* Likewise, but record LOC as the program location. */
11175 bool
11177 {
11180 }
11182 /* We're done instantiating this template; return to the instantiation
11183 context. */
11185 void
11187 {
11188 /* Restore the filename and line number stashed away when we started
11189 this instantiation. */
11193 }
11195 /* We're instantiating a deferred template; restore the template
11196 instantiation context in which the instantiation was requested, which
11197 is one step out from LEVEL. Return the corresponding DECL or TYPE. */
11199 static tree
11201 {
11213 }
11215 /* Returns the TINST_LEVEL which gives the original instantiation
11216 context. */
11220 {
11226 }
11228 /* True iff T is a friend function declaration that is not itself a template
11229 and is not defined in a class template. */
11231 bool
11233 {
11236 {
11240 /* DECL_FRIEND_CONTEXT is set for a friend defined in class. */
11243 /* Non-templated friends in a class template are still represented with a
11244 TEMPLATE_DECL; check that its primary template is the befriending
11245 class. Note that DECL_PRIMARY_TEMPLATE is null for
11246 template <class T> friend A<T>::f(); */
11250 }
11251 else
11253 }
11255 /* DECL is a friend FUNCTION_DECL or TEMPLATE_DECL. ARGS is the
11256 vector of template arguments, as for tsubst.
11258 Returns an appropriate tsubst'd friend declaration. */
11260 static tree
11262 {
11263 tree new_friend;
11268 /* This was a friend declared with an explicit template
11269 argument list, e.g.:
11271 friend void f<>(T);
11273 to indicate that f was a template instantiation, not a new
11274 function declaration. Now, we have to figure out what
11275 instantiation of what template. */
11276 {
11278 tree new_args;
11279 tree tmpl;
11282 /* Friend functions are looked up in the containing namespace scope.
11283 We must enter that scope, to avoid finding member functions of the
11284 current class with same name. */
11298 tsk_none);
11300 }
11306 /* The NEW_FRIEND will look like an instantiation, to the
11307 compiler, but is not an instantiation from the point of view of
11308 the language. For example, we might have had:
11310 template <class T> struct S {
11311 template <class U> friend void f(T, U);
11312 };
11314 Then, in S<int>, template <class U> void f(int, U) is not an
11315 instantiation of anything. */
11319 {
11325 /* Substitute TEMPLATE_PARMS_CONSTRAINTS so that parameter levels will
11326 match in decls_match. */
11331 {
11333 /* As well as each TEMPLATE_PARM_CONSTRAINTS. */
11335 tf_warning_or_error);
11336 }
11337 }
11339 /* The mangled name for the NEW_FRIEND is incorrect. The function
11340 is not a template instantiation and should not be mangled like
11341 one. Therefore, we forget the mangling here; we'll recompute it
11342 later if we need it. */
11344 {
11347 }
11350 {
11351 tree old_decl;
11352 tree ns;
11354 /* We must save some information from NEW_FRIEND before calling
11355 duplicate decls since that function will free NEW_FRIEND if
11356 possible. */
11360 (new_friend_template_info
11367 {
11368 /* This declaration is a `primary' template. */
11373 }
11375 /* Inside pushdecl_namespace_level, we will push into the
11376 current namespace. However, the friend function should go
11377 into the namespace of the template. */
11387 {
11388 /* This new friend declaration matched an existing
11389 declaration. For example, given:
11391 template <class T> void f(T);
11392 template <class U> class C {
11393 template <class T> friend void f(T) {}
11394 };
11396 the friend declaration actually provides the definition
11397 of `f', once C has been instantiated for some type. So,
11398 old_decl will be the out-of-class template declaration,
11399 while new_friend is the in-class definition.
11401 But, if `f' was called before this point, the
11402 instantiation of `f' will have DECL_TI_ARGS corresponding
11403 to `T' but not to `U', references to which might appear
11404 in the definition of `f'. Previously, the most general
11405 template for an instantiation of `f' was the out-of-class
11406 version; now it is the in-class version. Therefore, we
11407 run through all specialization of `f', adding to their
11408 DECL_TI_ARGS appropriately. In particular, they need a
11409 new set of outer arguments, corresponding to the
11410 arguments for this class instantiation.
11412 The same situation can arise with something like this:
11414 friend void f(int);
11415 template <class T> class C {
11416 friend void f(T) {}
11417 };
11419 when `C<int>' is instantiated. Now, `f(int)' is defined
11420 in the class. */
11423 /* On the other hand, if the in-class declaration does
11424 *not* provide a definition, then we don't want to alter
11425 existing definitions. We can just leave everything
11426 alone. */
11427 ;
11428 else
11429 {
11433 /* Overwrite whatever template info was there before, if
11434 any, with the new template information pertaining to
11435 the declaration. */
11439 {
11440 /* We should have called reregister_specialization in
11441 duplicate_decls. */
11446 /* Instantiate it if the global has already been used. */
11450 }
11451 else
11452 {
11453 tree t;
11455 /* Indicate that the old function template is a partial
11456 instantiation. */
11464 /* Reassign any specializations already in the hash table
11465 to the new more general template, and add the
11466 additional template args. */
11470 {
11472 spec_entry elt;
11484 register_specialization
11487 }
11489 }
11490 }
11492 /* The information from NEW_FRIEND has been merged into OLD_DECL
11493 by duplicate_decls. */
11495 }
11497 /* We've just introduced a namespace-scope function in the purview
11498 without necessarily having opened the enclosing namespace, so
11499 make sure the namespace is in the purview now too. */
11504 }
11505 else
11506 {
11510 /* In the code
11511 template <class T> class C {
11512 template <class U> friend void C1<U>::f (); // case 1
11513 friend void C2<T>::f (); // case 2
11514 };
11515 we only need to make sure CONTEXT is a complete type for
11516 case 2. To distinguish between the two cases, we note that
11517 CONTEXT of case 1 remains dependent type after tsubst while
11518 this isn't true for case 2. */
11528 {
11530 /* do_friend adds the TEMPLATE_DECL for any member friend
11531 template even if it isn't a member template, i.e.
11532 template <class T> friend A<T>::f();
11533 Look through it in that case. */
11537 /* Check to see that the declaration is really present, and,
11538 possibly obtain an improved declaration. */
11543 }
11544 }
11547 }
11549 /* FRIEND_TMPL is a friend TEMPLATE_DECL. ARGS is the vector of
11550 template arguments, as for tsubst.
11552 Returns an appropriate tsubst'd friend type or error_mark_node on
11553 failure. */
11555 static tree
11557 {
11558 tree tmpl;
11561 {
11564 }
11569 else
11570 {
11573 }
11579 {
11580 /* The friend template has already been declared. Just
11581 check to see that the declarations match, and install any new
11582 default parameters. We must tsubst the default parameters,
11583 of course. We only need the innermost template parameters
11584 because that is all that redeclare_class_template will look
11585 at. */
11588 {
11592 tf_warning_or_error);
11602 }
11603 }
11604 else
11605 {
11606 /* The friend template has not already been declared. In this
11607 case, the instantiation of the template class will cause the
11608 injection of this template into the namespace scope. */
11612 {
11613 /* The new TMPL is not an instantiation of anything, so we
11614 forget its origins. We don't reset CLASSTYPE_TI_TEMPLATE
11615 for the new type because that is supposed to be the
11616 corresponding template decl, i.e., TMPL. */
11623 /* Substitute into and set the constraints on the new declaration. */
11625 {
11633 }
11635 /* Inject this template into the enclosing namspace scope. */
11637 }
11638 }
11642 else
11646 }
11648 /* Returns zero if TYPE cannot be completed later due to circularity.
11649 Otherwise returns one. */
11651 static int
11653 {
11663 else
11665 }
11670 /* Instantiate the contract statement. */
11672 static tree
11674 tree in_decl)
11675 {
11681 /* Rebuild the result variable. */
11683 {
11691 /* Make sure the postcondition is valid. */
11697 /* Make the variable available for lookup. */
11699 }
11701 /* Instantiate the condition. If the return type is undeduced, process
11702 the expression as if inside a template to avoid spurious type errors. */
11712 /* And the comment. */
11717 }
11719 /* Update T by instantiating its contract attribute. */
11721 static void
11724 {
11725 /* For non-specializations, adjust the current declaration to the most general
11726 version of in_decl. Because we defer the instantiation of contracts as long
11727 as possible, they are still written in terms of the parameters (and return
11728 type) of the most general template. */
11735 /* Get the contract to be instantiated. */
11738 /* Use the complete set of template arguments for instantiation. The
11739 contract may not have been instantiated and still refer to outer levels
11740 of template parameters. */
11743 /* For member functions, make this available for semantic analysis. */
11747 {
11751 }
11758 /* Rebuild the attribute. */
11760 }
11762 /* Rebuild the attribute list for DECL, substituting into contracts
11763 as needed. */
11765 void
11767 {
11770 {
11773 }
11775 }
11777 /* Instantiate a single dependent attribute T (a TREE_LIST), and return either
11778 T or a new TREE_LIST, possibly a chain in the case of a pack expansion. */
11780 static tree
11783 {
11786 /* Note that contract attributes are never substituted from this function.
11787 Their instantiation is triggered by regenerate_from_template_decl when
11788 we instantiate the body of the function. */
11796 {
11803 clauses
11807 else
11809 }
11813 {
11824 {
11828 {
11830 {
11838 }
11839 else
11840 {
11844 {
11845 bool allow_string
11857 {
11858 location_t loc
11860 match_loc);
11866 "integer expression or string "
11868 else
11872 }
11875 {
11876 location_t loc
11878 match_loc);
11882 }
11884 }
11885 }
11886 }
11887 }
11889 }
11890 /* If the first attribute argument is an identifier, don't
11891 pass it through tsubst. Attributes like mode, format,
11892 cleanup and several target specific attributes expect it
11893 unmodified. */
11895 {
11896 tree chain
11900 }
11902 {
11903 /* An attribute pack expansion. */
11912 {
11916 }
11918 }
11919 else
11927 }
11929 /* Instantiate any dependent attributes in ATTRIBUTES, returning either it
11930 unchanged or a new TREE_LIST chain. */
11932 static tree
11935 {
11940 {
11944 }
11948 {
11951 {
11954 {
11960 }
11961 }
11963 }
11966 }
11968 /* Apply any attributes which had to be deferred until instantiation
11969 time. DECL_P, ATTRIBUTES and ATTR_FLAGS are as cplus_decl_attributes;
11970 ARGS, COMPLAIN, IN_DECL are as tsubst. Returns true normally,
11971 false on error. */
11973 static bool
11976 {
11977 tree t;
11984 {
11988 /* DECL_ATTRIBUTES comes from copy_node in tsubst_decl, and is identical
11989 to our attributes parameter. */
11991 }
11992 else
11993 {
11995 /* TYPE_ATTRIBUTES was set up (with abi_tag and may_alias) in
11996 lookup_template_class_1, and should be preserved. */
12000 }
12002 /* save_template_attributes puts the dependent attributes at the beginning of
12003 the list; find the non-dependent ones. */
12009 /* Apply any non-dependent attributes. */
12015 /* And then any dependent ones. */
12019 {
12024 {
12027 }
12030 }
12032 /* cplus_decl_attributes can add some attributes implicitly. For templates,
12033 those attributes should have been added already when those templates were
12034 parsed, and shouldn't be added based on from which context they are
12035 first time instantiated. */
12038 optimization_default_node);
12041 NULL);
12047 }
12049 /* The template TMPL is being instantiated with the template arguments TARGS.
12050 Perform the access checks that we deferred when parsing the template. */
12052 static void
12054 {
12064 {
12072 /* Make access check error messages point to the location
12073 of the use of the typedef. */
12077 }
12078 }
12080 tree
12082 {
12086 tree typedecl;
12087 tree pbinfo;
12088 tree base_list;
12090 tree fn_context;
12100 /* Figure out which template is being instantiated. */
12104 /* Mark the type as in the process of being defined. */
12107 /* We may be in the middle of deferred access check. Disable
12108 it now. */
12111 /* Determine what specialization of the original template to
12112 instantiate. */
12117 {
12118 /* This TYPE is actually an instantiation of a partial
12119 specialization. We replace the innermost set of ARGS with
12120 the arguments appropriate for substitution. For example,
12121 given:
12123 template <class T> struct S {};
12124 template <class T> struct S<T*> {};
12126 and supposing that we are instantiating S<int*>, ARGS will
12127 presently be {int*} -- but we need {int}. */
12130 }
12131 else
12132 {
12135 }
12137 /* If the template we're instantiating is incomplete, then clearly
12138 there's nothing we can do. */
12140 {
12141 /* We can try again later. */
12144 }
12146 /* If we've recursively instantiated too many templates, stop. */
12154 /* Also avoid push_to_top_level for a lambda in an NSDMI. */
12159 else
12160 {
12163 }
12167 /* Use #pragma pack from the template context. */
12173 /* Set the input location to the most specialized template definition.
12174 This is needed if tsubsting causes an error. */
12188 {
12191 /* Adjust visibility for template arguments. */
12193 }
12199 /* We should never instantiate a nested class before its enclosing
12200 class; we need to look up the nested class by name before we can
12201 instantiate it, and that lookup should instantiate the enclosing
12202 class. */
12207 /* Defer access checking while we substitute into the types named in
12208 the base-clause. */
12211 {
12212 tree pbase_binfo;
12215 /* Substitute into each of the bases to determine the actual
12216 basetypes. */
12218 {
12219 tree base;
12225 {
12226 expanded_bases =
12233 }
12236 {
12238 /* Extract the already-expanded base class. */
12240 else
12241 /* Substitute to figure out the base class. */
12243 NULL_TREE);
12251 }
12252 }
12254 /* The list is now in reverse order; correct that. */
12256 }
12257 /* Now call xref_basetypes to set up all the base-class
12258 information. */
12266 /* Now that our base classes are set up, enter the scope of the
12267 class, so that name lookups into base classes, etc. will work
12268 correctly. This is precisely analogous to what we do in
12269 begin_class_definition when defining an ordinary non-template
12270 class, except we also need to push the enclosing classes. */
12273 /* Now check accessibility of the types named in its base-clause,
12274 relative to the scope of the class. */
12277 /* A vector to hold members marked with attribute used. */
12280 /* Now members are processed in the order of declaration. */
12283 {
12287 {
12289 {
12291 /* A closure type for a lambda in an NSDMI or default argument.
12292 Ignore it; it will be regenerated when needed. */
12295 /* If the member is a class template, we've
12296 already substituted its type. */
12306 {
12309 /* Now, install the tag. We don't use pushtag
12310 because that does too much work -- creating an
12311 implicit typedef, which we've already done. */
12316 }
12317 }
12319 {
12320 tree r;
12330 /* Instantiate members marked with attribute used. */
12336 }
12339 /* A closure type for a lambda in an NSDMI or default argument.
12341 else
12342 {
12343 /* Build new TYPE_FIELDS. */
12347 {
12348 tree r;
12353 /* The file and line for this declaration, to
12354 assist in error message reporting. Since we
12355 called push_tinst_level above, we don't need to
12356 restore these. */
12366 {
12367 /* A capture pack became multiple fields. */
12370 }
12373 {
12377 {
12378 /* In [temp.inst]:
12380 [t]he initialization (and any associated
12381 side-effects) of a static data member does
12382 not occur unless the static data member is
12383 itself used in a way that requires the
12384 definition of the static data member to
12385 exist.
12387 Therefore, we do not substitute into the
12388 initialized for the static data member here. */
12389 finish_static_data_member_decl
12395 /* Instantiate members marked with attribute used. */
12398 }
12400 {
12401 /* Determine whether R has a valid type and can be
12402 completed later. If R is invalid, then its type
12403 is replaced by error_mark_node. */
12409 {
12410 /* If R's type couldn't be completed and
12411 it isn't a flexible array member (whose
12412 type is incomplete by definition) give
12413 an error. */
12416 }
12421 {
12424 }
12428 }
12430 /* If it is a TYPE_DECL for a class-scoped
12431 ENUMERAL_TYPE, such a thing will already have
12432 been added to the field list by tsubst_enum
12433 in finish_member_declaration case above. */
12437 {
12440 }
12441 }
12442 }
12443 }
12444 }
12445 else
12446 {
12449 {
12450 /* Build new CLASSTYPE_FRIEND_CLASSES. */
12454 {
12455 /* template <class T> friend class C; */
12457 }
12459 {
12460 /* template <class T> friend class C::D; */
12465 }
12468 {
12469 /* This could be either
12471 friend class T::C;
12473 when dependent_type_p is false or
12475 template <class U> friend class T::C;
12477 otherwise. */
12478 /* Bump processing_template_decl in case this is something like
12479 template <class T> friend struct A<T>::B. */
12484 }
12486 /* friend class C<T>; */
12490 /* Otherwise it's
12492 friend class C;
12494 where C is already declared or
12496 friend class C<int>;
12498 We don't have to do anything in these cases. */
12502 }
12503 else
12504 {
12505 /* Build new DECL_FRIENDLIST. */
12506 tree r;
12508 /* The file and line for this declaration, to
12509 assist in error message reporting. Since we
12510 called push_tinst_level above, we don't need to
12511 restore these. */
12515 {
12518 }
12523 {
12526 }
12527 }
12528 }
12529 }
12532 {
12533 /* Restore these before substituting into the lambda capture
12534 initializers. */
12537 }
12539 /* Set the file and line number information to whatever is given for
12540 the class itself. This puts error messages involving generated
12541 implicit functions at a predictable point, and the same point
12542 that would be used for non-template classes. */
12549 /* Remember if instantiating this class ran into errors, so we can avoid
12550 instantiating member functions in limit_bad_template_recursion. We set
12551 this flag even if the problem was in another instantiation triggered by
12552 this one, as that will likely also cause trouble for member functions. */
12556 /* We don't instantiate default arguments for member functions. 14.7.1:
12558 The implicit instantiation of a class template specialization causes
12559 the implicit instantiation of the declarations, but not of the
12560 definitions or default arguments, of the class member functions,
12561 member classes, static data members and member templates.... */
12566 /* Now that we've gone through all the members, instantiate those
12567 marked with attribute used. We must do this in the context of
12568 the class -- not the context we pushed from, as that might be
12569 inside a template and change the behaviour of mark_used. */
12579 /* The vtable for a template class can be emitted in any translation
12580 unit in which the class is instantiated. When there is no key
12581 method, however, finish_struct_1 will already have added TYPE to
12582 the keyed_classes. */
12587 }
12589 tree
12591 {
12592 tree r;
12598 else
12599 {
12605 }
12608 }
12610 /* Given a function parameter pack TMPL_PARM and some function parameters
12611 instantiated from it at *SPEC_P, return a NONTYPE_ARGUMENT_PACK of them
12612 and set *SPEC_P to point at the next point in the list. */
12614 tree
12616 {
12617 /* Collect all of the extra "packed" parameters into an
12618 argument pack. */
12619 tree argpack;
12630 {
12631 /* The instantiation is still a parameter pack; don't wrap it in a
12632 NONTYPE_ARGUMENT_PACK. */
12635 }
12636 else
12637 {
12638 /* Fill in PARMVEC with all of the parameters. */
12642 {
12648 }
12650 /* Build the argument packs. */
12652 }
12656 }
12658 /* Give a chain SPEC_PARM of PARM_DECLs, pack them into a
12659 NONTYPE_ARGUMENT_PACK. */
12661 static tree
12663 {
12665 }
12667 /* Return 1 if the Ith element of the argument pack ARG_PACK is a
12668 pack expansion with no extra args, 2 if it has extra args, or 0
12669 if it is not a pack expansion. */
12671 static int
12673 {
12675 /* We're being called before this happens in tsubst_pack_expansion. */
12682 /* A decl pack is itself an expansion. */
12689 }
12692 /* Creates and return an ARGUMENT_PACK_SELECT tree node. */
12694 static tree
12696 {
12703 }
12705 /* This is a subroutine of tsubst_pack_expansion.
12707 It returns TRUE if we need to use the PACK_EXPANSION_EXTRA_ARGS
12708 mechanism to store the (non complete list of) arguments of the
12709 substitution and return a non substituted pack expansion, in order
12710 to wait for when we have enough arguments to really perform the
12711 substitution. */
12713 static bool
12715 tree parm_packs,
12718 {
12723 /* If one pack has an expansion and another pack has a normal
12724 argument or if one pack has an empty argument and an another
12725 one hasn't then tsubst_pack_expansion cannot perform the
12726 substitution and need to fall back on the
12727 PACK_EXPANSION_EXTRA mechanism. */
12731 {
12732 /* If all the actual packs are pack expansions, we can still
12733 subsitute directly. */
12735 {
12745 }
12747 }
12750 {
12754 parm_pack;
12756 {
12761 /* We can't substitute a pack expansion with extra args into
12762 our pattern. */
12766 else
12768 }
12771 {
12774 }
12775 }
12777 }
12779 /* [temp.variadic]/6 says that:
12781 The instantiation of a pack expansion [...]
12782 produces a list E1,E2, ..., En, where N is the number of elements
12783 in the pack expansion parameters.
12785 This subroutine of tsubst_pack_expansion produces one of these Ei.
12787 PATTERN is the pattern of the pack expansion. PARM_PACKS is a
12788 TREE_LIST in which each TREE_PURPOSE is a parameter pack of
12789 PATTERN, and each TREE_VALUE is its corresponding argument pack.
12790 INDEX is the index 'i' of the element Ei to produce. ARGS,
12791 COMPLAIN, and IN_DECL are the same parameters as for the
12792 tsubst_pack_expansion function.
12794 The function returns the resulting Ei upon successful completion,
12795 or error_mark_node.
12797 Note that this function possibly modifies the ARGS parameter, so
12798 it's the responsibility of the caller to restore it. */
12800 static tree
12802 tree parm_packs,
12804 tree args /* This parm gets
12806 tsubst_flags_t complain,
12807 tree in_decl)
12808 {
12809 tree t;
12812 /* For each parameter pack, change the substitution of the parameter
12813 pack to the ith argument in its argument pack, then expand the
12814 pattern. */
12816 {
12821 ith_elem_is_expansion |=
12824 /* Select the Ith argument from the pack. */
12828 {
12830 {
12835 }
12836 else
12838 }
12839 else
12840 {
12845 {
12847 /* Update the corresponding argument. */
12849 }
12850 else
12851 /* Re-use the ARGUMENT_PACK_SELECT. */
12853 }
12855 }
12857 /* Substitute into the PATTERN with the (possibly altered)
12858 arguments. */
12860 /* Expanding a fixed parameter pack from
12861 coerce_template_parameter_pack. */
12867 else
12868 {
12871 /* When expanding the fake auto... pack expansion from add_capture, we
12872 need to mark that the expansion is no longer a pack. */
12874 }
12876 /* If the Ith argument pack element is a pack expansion, then
12877 the Ith element resulting from the substituting is going to
12878 be a pack expansion as well. */
12883 }
12885 /* When the unexpanded parameter pack in a fold expression expands to an empty
12886 sequence, the value of the expression is as follows; the program is
12887 ill-formed if the operator is not listed in this table.
12889 && true
12890 || false
12891 , void() */
12893 tree
12895 {
12899 {
12908 }
12914 }
12916 /* Given a fold-expression T and a current LEFT and RIGHT operand,
12917 form an expression that combines the two terms using the
12918 operator of T. */
12920 static tree
12922 {
12927 // Handle compound assignment operators.
12934 {
12943 complain);
12944 }
12945 }
12947 /* Substitute ARGS into the pack of a fold expression T. */
12951 {
12953 }
12955 /* Substitute ARGS into the pack of a fold expression T. */
12959 {
12961 }
12963 /* Expand a PACK of arguments into a grouped as left fold.
12964 Given a pack containing elements A0, A1, ..., An and an
12965 operator @, this builds the expression:
12967 ((A0 @ A1) @ A2) ... @ An
12969 Note that PACK must not be empty.
12971 The operator is defined by the original fold expression T. */
12973 static tree
12975 {
12978 {
12981 }
12983 }
12985 /* Substitute into a unary left fold expression. */
12987 static tree
12989 tree in_decl)
12990 {
12995 {
12999 }
13002 else
13004 }
13006 /* Substitute into a binary left fold expression.
13008 Do ths by building a single (non-empty) vector of argumnts and
13009 building the expression from those elements. */
13011 static tree
13013 tree in_decl)
13014 {
13023 {
13028 }
13036 }
13038 /* Expand a PACK of arguments into a grouped as right fold.
13039 Given a pack containing elementns A0, A1, ..., and an
13040 operator @, this builds the expression:
13042 A0@ ... (An-2 @ (An-1 @ An))
13044 Note that PACK must not be empty.
13046 The operator is defined by the original fold expression T. */
13048 tree
13050 {
13051 // Build the expression.
13055 {
13058 }
13060 }
13062 /* Substitute into a unary right fold expression. */
13064 static tree
13066 tree in_decl)
13067 {
13072 {
13076 }
13079 else
13081 }
13083 /* Substitute into a binary right fold expression.
13085 Do ths by building a single (non-empty) vector of arguments and
13086 building the expression from those elements. */
13088 static tree
13090 tree in_decl)
13091 {
13100 {
13105 }
13114 }
13116 /* Walk through the pattern of a pack expansion, adding everything in
13117 local_specializations to a list. */
13119 class el_data
13120 {
13122 /* Set of variables declared within the pattern. */
13124 /* Set of AST nodes that have been visited by the traversal. */
13126 /* List of local_specializations used within the pattern. */
13127 tree extra;
13128 tsubst_flags_t complain;
13129 /* True iff we don't want to walk into unevaluated contexts. */
13131 /* The unevaluated contexts that we avoided walking. */
13136 };
13137 static tree
13139 {
13146 {
13150 }
13153 /* Remember local typedefs (85214). */
13157 {
13163 {
13166 decl2
13172 {
13175 }
13176 }
13177 }
13179 {
13180 /* Since we defer implicit capture, look in the parms and body. */
13186 }
13188 {
13190 /* Don't mess with variables declared within the pattern. */
13193 {
13194 /* Maybe pull out the PARM_DECL for a partial instantiation. */
13197 {
13203 }
13205 {
13206 /* Handle lambda capture here, since we aren't doing any
13207 substitution now, and so tsubst_copy won't call
13208 process_outer_var_ref. */
13212 {
13218 {
13219 /* Make a new NONTYPE_ARGUMENT_PACK of the capture
13220 proxies. */
13222 {
13227 }
13229 }
13230 }
13231 }
13232 }
13236 }
13238 }
13239 static tree
13241 {
13243 /* Walk the pattern twice, ignoring unevaluated operands the first time
13244 around, so that if a local specialization appears in both an evaluated
13245 and unevaluated context we prefer to process it in the evaluated context
13246 (since e.g. process_outer_var_ref is a no-op inside an unevaluated
13247 context). */
13250 /* Now walk the unevaluated contexts we skipped the first time around. */
13253 {
13256 }
13258 }
13260 /* Extract any uses of local_specializations from PATTERN and add them to ARGS
13261 for use in PACK_EXPANSION_EXTRA_ARGS. */
13263 tree
13265 {
13266 /* Make a copy of the extra arguments so that they won't get changed
13267 out from under us. */
13273 }
13275 /* Apply any local specializations from PACK_EXPANSION_EXTRA_ARGS and add the
13276 normal template args to ARGS. */
13278 tree
13280 {
13282 {
13284 {
13285 /* The partial instantiation involved local declarations collected in
13286 extract_local_specs; map from the general template to our local
13287 context. */
13293 /* else inst is already a full instantiation of the pack. */
13295 }
13298 }
13300 {
13301 /* This can happen after dependent substitution into a
13302 requires-expr or a lambda that uses constexpr if. */
13305 }
13306 else
13309 }
13311 /* Substitute ARGS into T, which is an pack expansion
13312 (i.e. TYPE_PACK_EXPANSION or EXPR_PACK_EXPANSION). Returns a
13313 TREE_VEC with the substituted arguments, a PACK_EXPANSION_* node
13314 (if only a partial substitution could be performed) or
13315 ERROR_MARK_NODE if there was an error. */
13316 tree
13318 tree in_decl)
13319 {
13320 tree pattern;
13324 tree result;
13331 /* Add in any args remembered from an earlier partial instantiation. */
13336 /* Determine the argument packs that will instantiate the parameter
13337 packs used in the expansion expression. While we're at it,
13338 compute the number of arguments to be expanded and make sure it
13339 is consistent. */
13342 {
13349 {
13354 else
13356 }
13358 {
13360 {
13363 parm_pack);
13365 }
13368 }
13370 {
13371 /* We know we have correct local_specializations if this
13372 expansion is at function scope, or if we're dealing with a
13373 local parameter in a requires expression; for the latter,
13374 tsubst_requires_expr set it up appropriately. */
13377 else
13378 /* We can't rely on local_specializations for a parameter
13379 name used later in a function declaration (such as in a
13380 late-specified return type). Even if it exists, it might
13381 have the wrong value for a recursive call. */
13385 {
13386 /* This parameter pack was used in an unevaluated context. Just
13387 make a dummy decl, since it's only used for its type. */
13392 /* Partial instantiation of the parm_pack, we can't build
13393 up an argument pack yet. */
13395 else
13397 }
13399 /* This argument pack isn't fully instantiated yet. */
13401 }
13403 {
13407 }
13408 else
13409 {
13418 }
13425 /* This can only happen if we forget to expand an argument
13426 pack somewhere else. Just return an error, silently. */
13427 {
13431 }
13434 {
13438 /* Don't bother trying to do a partial substitution with
13439 incomplete packs; we'll try again after deduction. */
13446 {
13451 pattern);
13452 else
13454 pattern);
13456 }
13458 /* Keep track of the parameter packs and their corresponding
13459 argument packs. */
13462 }
13463 else
13464 {
13465 /* We can't substitute for this parameter pack. We use a flag as
13466 well as the missing_level counter because function parameter
13467 packs don't have a level. */
13470 }
13471 }
13473 /* If the expansion is just T..., return the matching argument pack, unless
13474 we need to call convert_from_reference on all the elements. This is an
13475 important optimization; see c++/68422. */
13478 {
13481 /* If the argument pack is a single pack expansion, pull it out. */
13486 /* Types need no adjustment, nor does sizeof..., and if we still have
13487 some pack expansion args we won't do anything yet. */
13492 /* Also optimize expression pack expansions if we can tell that the
13493 elements won't have reference type. */
13499 /* Otherwise use the normal path so we get convert_from_reference. */
13500 }
13502 /* We cannot expand this expansion expression, because we don't have
13503 all of the argument packs we need. */
13505 {
13506 /* We got some full packs, but we can't substitute them in until we
13507 have values for all the packs. So remember these until then. */
13513 }
13515 /* If NEED_LOCAL_SPECIALIZATIONS then we're in a late-specified return
13516 type, so create our own local specializations map; the current map is
13517 either NULL or (in the case of recursive unification) might have
13518 bindings that we don't want to use or alter. */
13523 {
13524 /* There were no real arguments, we're just replacing a parameter
13525 pack with another version of itself. Substitute into the
13526 pattern and return a PACK_EXPANSION_*. The caller will need to
13527 deal with that. */
13530 else
13536 {
13537 /* This is a fake auto... pack expansion created in add_capture with
13538 _PACKS that don't appear in the pattern. Copy one over. */
13545 }
13547 }
13551 /* For each argument in each argument pack, substitute into the
13552 pattern. */
13556 {
13558 i,
13560 in_decl);
13563 {
13566 }
13567 }
13569 /* Update ARGS to restore the substitution from parameter packs to
13570 their argument packs. */
13572 {
13579 else
13580 {
13588 /* Update the corresponding argument. */
13592 else
13594 }
13595 }
13597 /* If the dependent pack arguments were such that we end up with only a
13598 single pack expansion again, there's no need to keep it in a TREE_VEC. */
13604 }
13606 /* Make an argument pack out of the TREE_VEC VEC. */
13608 static tree
13610 {
13611 tree pack;
13615 else
13616 {
13619 }
13622 }
13624 /* Return an exact copy of template args T that can be modified
13625 independently. */
13627 static tree
13629 {
13637 {
13642 }
13648 }
13650 /* Substitute ARGS into the *_ARGUMENT_PACK orig_arg. */
13652 tree
13654 tree in_decl)
13655 {
13656 /* This flag is used only during deduction, and we don't expect to
13657 substitute such ARGUMENT_PACKs. */
13660 /* Substitute into each of the arguments. */
13669 /* If we're substituting into a generic ARGUMENT_PACK for a variadic
13670 template parameter, we might be able to avoid allocating a new
13671 ARGUMENT_PACK and reuse the corresponding ARGUMENT_PACK from ARGS
13672 if the substituted result is identical to it. */
13674 {
13681 {
13684 }
13685 }
13687 tree new_arg;
13689 {
13692 }
13693 else
13694 {
13697 }
13700 }
13702 /* Substitute ARGS into the vector or list of template arguments T. */
13704 tree
13706 {
13710 /* In "sizeof(X<I>)" we need to evaluate "I". */
13711 cp_evaluated ev;
13717 /* True iff the substituted result is identical to T. */
13721 {
13723 tree new_arg;
13730 {
13731 /* Substitute into an expansion expression. */
13735 /* Add to the expanded length adjustment the number of
13736 expanded arguments. We subtract one from this
13737 measurement, because the argument pack expression
13738 itself is already counted as 1 in
13739 LEN. EXPANDED_LEN_ADJUST can actually be negative, if
13740 the argument pack is empty. */
13742 }
13745 else
13754 }
13761 /* If ARGS and T are both multi-level, the substituted result may be
13762 identical to ARGS. */
13767 /* If T appears to be a vector of generic template arguments, the
13768 substituted result may be identical to the corresponding level
13769 from ARGS. */
13771 {
13776 }
13778 /* If the substituted result is identical to MAYBE_REUSE, return
13779 it and avoid allocating a new TREE_VEC, as an optimization. */
13785 /* If T consists of only a pack expansion for which substitution yielded
13786 a TREE_VEC of the expanded elements, then reuse that TREE_VEC instead
13787 of effectively making a copy. */
13793 /* Make space for the expanded arguments coming from template
13794 argument packs. */
13796 /* T can contain TREE_VECs. That happens if T contains the
13797 arguments for a member template.
13798 In that case each TREE_VEC in T represents a level of template
13799 arguments, and T won't carry any non defaulted argument count.
13800 It will rather be the nested TREE_VECs that will carry one.
13801 In other words, T carries a non defaulted argument count only
13802 if it doesn't contain any nested TREE_VEC. */
13804 {
13808 }
13812 {
13817 {
13818 /* Now expand the template argument pack "in place". */
13821 }
13822 else
13823 {
13825 out++;
13826 }
13827 }
13831 }
13833 /* Substitute ARGS into one level PARMS of template parameters. */
13835 static tree
13837 {
13844 {
13852 }
13855 }
13857 /* Return the result of substituting ARGS into the template parameters
13858 given by PARMS. If there are m levels of ARGS and m + n levels of
13859 PARMS, then the result will contain n levels of PARMS. For
13860 example, if PARMS is `template <class T> template <class U>
13861 template <T*, U, class V>' and ARGS is {{int}, {double}} then the
13862 result will be `template <int*, double, class V>'. */
13864 static tree
13866 {
13870 /* When substituting into a template, we must set
13871 PROCESSING_TEMPLATE_DECL as the template parameters may be
13872 dependent if they are based on one-another, and the dependency
13873 predicates are short-circuit outside of templates. */
13880 {
13889 }
13894 }
13896 /* Return the result of substituting ARGS into one template parameter
13897 given by T. T Must be a TREE_LIST which TREE_VALUE is the template
13898 parameter and which TREE_PURPOSE is the default argument of the
13899 template parameter. */
13901 static tree
13903 {
13926 }
13928 /* Substitute in-place the TEMPLATE_PARM_CONSTRAINTS of each template
13929 parameter in PARMS for sake of declaration matching. */
13931 static void
13933 tsubst_flags_t complain)
13934 {
13937 {
13943 }
13945 }
13947 /* Substitute the ARGS into the indicated aggregate (or enumeration)
13948 type T. If T is not an aggregate or enumeration type, it is
13949 handled as if by tsubst. IN_DECL is as for tsubst. If
13950 ENTERING_SCOPE is nonzero, T is the context for a template which
13951 we are presently tsubst'ing. Return the substituted value. */
13953 static tree
13955 tree args,
13956 tsubst_flags_t complain,
13957 tree in_decl,
13959 {
13963 /* Handle typedefs via tsubst so that they get consistently reused. */
13965 {
13970 /* The effect of entering_scope is that for a dependent specialization
13971 A<T>, lookup_template_class prefers to return A's primary template
13972 type instead of the implicit instantiation. So when entering_scope,
13973 we mirror this behavior by inspecting TYPE_CANONICAL appropriately,
13974 taking advantage of the fact that lookup_template_class links the two
13975 types by setting TYPE_CANONICAL of the latter to the former. */
13984 }
13987 {
13995 }
13996 }
13998 /* The part of tsubst_aggr_type that's shared with the RECORD_, UNION_
13999 and ENUMERAL_TYPE cases of tsubst. */
14001 static tree
14003 tree args,
14004 tsubst_flags_t complain,
14005 tree in_decl,
14007 {
14009 {
14012 /* Figure out what arguments are appropriate for the
14013 type we are trying to find. For example, given:
14015 template <class T> struct S;
14016 template <class T, class U> void f(T, U) { S<U> su; }
14018 and supposing that we are instantiating f<int, double>,
14019 then our ARGS will be {int, double}, but, when looking up
14020 S we only want {double}. */
14029 }
14030 else
14031 /* This is not a template type, so there's nothing to do. */
14033 }
14035 /* Map from a FUNCTION_DECL to a vec of default argument instantiations,
14036 indexed in reverse order of the parameters. */
14040 /* Return a reference to the vec* of defarg insts for FN. */
14044 {
14048 tree_vec_map **slot
14051 {
14054 }
14056 }
14058 /* Substitute into the default argument ARG (a default argument for
14059 FN), which has the indicated TYPE. */
14061 tree
14063 tsubst_flags_t complain)
14064 {
14067 /* This can happen in invalid code. */
14071 /* Shortcut {}. */
14086 /* Remember the location of the pointer to the vec rather than the location
14087 of the particular element, in case the vec grows in tsubst_expr. */
14089 /* Index in reverse order to avoid allocating space for initial parameters
14090 that don't have default arguments. */
14097 /* This default argument came from a template. Instantiate the
14098 default argument here, not in tsubst. In the case of
14099 something like:
14101 template <class T>
14102 struct S {
14103 static T t();
14104 void f(T = t());
14105 };
14107 we must be careful to do name lookup in the scope of S<T>,
14108 rather than in the current class. */
14112 /* So in_immediate_context knows this is a default argument. */
14116 /* The default argument expression may cause implicitly defined
14117 member functions to be synthesized, which will result in garbage
14118 collection. We must treat this situation as if we were within
14119 the body of function so as to avoid collecting live data on the
14120 stack. */
14127 /* Make sure the default argument is reasonable. */
14144 }
14146 /* Substitute into all the default arguments for FN. */
14148 static void
14150 {
14151 tree arg;
14152 tree tmpl_args;
14156 /* If this function is not yet instantiated, we certainly don't need
14157 its default arguments. */
14160 /* Don't do this again for clones. */
14166 arg;
14172 complain);
14173 }
14175 /* Hash table mapping a FUNCTION_DECL to its dependent explicit-specifier. */
14178 /* Store a pair to EXPLICIT_SPECIFIER_MAP. */
14180 void
14182 {
14187 }
14189 /* Lookup an element in EXPLICIT_SPECIFIER_MAP. */
14191 tree
14193 {
14195 }
14197 /* Given T, a FUNCTION_TYPE or METHOD_TYPE, construct and return a corresponding
14198 FUNCTION_TYPE or METHOD_TYPE whose return type is RETURN_TYPE, argument types
14199 are ARG_TYPES, and exception specification is RAISES, and otherwise is
14200 identical to T. */
14202 static tree
14205 {
14208 tree new_type;
14210 {
14213 }
14214 else
14215 {
14217 /* Don't pick up extra function qualifiers from the basetype. */
14220 {
14221 /* [temp.deduct]
14223 Type deduction may fail for any of the following
14224 reasons:
14226 -- Attempting to create "pointer to member of T" when T
14227 is not a class type. */
14230 r);
14232 }
14236 }
14242 }
14244 /* Check if the function type of DECL, a FUNCTION_DECL, agrees with the type of
14245 each of its formal parameters. If there is a disagreement then rebuild
14246 DECL's function type according to its formal parameter types, as part of a
14247 resolution for Core issues 1001/1322. */
14249 static void
14251 {
14254 {
14257 {
14261 {
14264 }
14268 }
14269 }
14280 {
14285 }
14287 {
14297 }
14305 }
14307 /* Subroutine of tsubst_decl for the case when T is a FUNCTION_DECL. */
14309 static tree
14312 {
14317 /* Nobody should be tsubst'ing into non-template functions. */
14322 {
14325 }
14327 {
14328 /* If T is not dependent, just return it. */
14333 /* A non-templated friend doesn't get DECL_TEMPLATE_INFO. */
14337 /* Calculate the most general template of which R is a
14338 specialization. */
14341 /* We're substituting a lambda function under tsubst_lambda_expr but not
14342 directly from it; find the matching function we're already inside.
14343 But don't do this if T is a generic lambda with a single level of
14344 template parms, as in that case we're doing a normal instantiation. */
14350 /* Calculate the complete set of arguments used to
14351 specialize R. */
14353 {
14355 (DECL_TEMPLATE_RESULT
14361 /* Check to see if we already have this specialization. */
14364 /* The spec for these args might be a partial instantiation of the
14365 template, but here what we want is the FUNCTION_DECL. */
14367 }
14368 else
14370 }
14371 else
14372 {
14373 /* This special case arises when we have something like this:
14375 template <class T> struct S {
14376 friend void f<int>(int, double);
14377 };
14379 Here, the DECL_TI_TEMPLATE for the friend declaration
14380 will be an IDENTIFIER_NODE. We are being called from
14381 tsubst_friend_function, and we want only to create a
14382 new decl (R) with appropriate types so that we can call
14383 determine_specialization. */
14384 friend_case:
14387 }
14394 /* If this is a static lambda, remove the 'this' pointer added in
14395 tsubst_lambda_expr now that we know the closure type. */
14409 /* If we hit excessive deduction depth, the type is bogus even if
14410 it isn't error_mark_node, so don't build a decl. */
14414 /* We do NOT check for matching decls pushed separately at this
14415 point, as they may not represent instantiations of this
14416 template, and in any case are considered separate under the
14417 discrete model. */
14421 /* Clear out the mangled name and RTL for the instantiation. */
14424 /* Leave DECL_INITIAL set on deleted instantiations. */
14430 /* Handle explicit(dependent-expr). */
14432 {
14440 else
14441 {
14444 }
14445 }
14447 /* OpenMP UDRs have the only argument a reference to the declared
14448 type. We want to diagnose if the declared type is a reference,
14449 which is invalid, but as references to references are usually
14450 quietly merged, diagnose it here. */
14452 {
14453 tree argtype
14458 "reference type %qT in "
14462 argtype);
14463 }
14466 /* Type-conversion operator. Reconstruct the name, in
14467 case it's the name of one of the template's parameters. */
14477 {
14482 }
14491 /* If this is an instantiation of a function with internal
14492 linkage, we already know what object file linkage will be
14493 assigned to the instantiation. */
14502 /* We'll re-clone as appropriate in instantiate_template. */
14505 /* If we aren't complaining now, return on error before we register
14506 the specialization so that we'll complain eventually. */
14512 /* Associate the constraints directly with the instantiation. We
14513 don't substitute through the constraints; that's only done when
14514 they are checked. */
14527 /* Set up the DECL_TEMPLATE_INFO for R. There's no need to do
14528 this in the special friend case mentioned above where
14529 GEN_TMPL is NULL. */
14531 {
14537 {
14538 tree new_r
14541 /* We instantiated this while substituting into
14542 the type earlier (template/friend54.C). */
14544 }
14546 /* We're not supposed to instantiate default arguments
14547 until they are called, for a template. But, for a
14548 declaration like:
14550 template <class T> void f ()
14551 { extern void g(int i = T()); }
14553 we should do the substitution when the template is
14554 instantiated. We handle the member function case in
14555 instantiate_class_template since the default arguments
14556 might refer to other members of the class. */
14561 }
14563 {
14566 }
14567 else
14570 /* Copy the list of befriending classes. */
14574 {
14578 }
14581 {
14585 /* If this is an instantiation of a member template, clone it.
14586 If it isn't, that'll be handled by
14587 clone_constructors_and_destructors. */
14590 }
14596 /* Possibly limit visibility based on template args. */
14599 {
14603 }
14615 }
14617 /* Subroutine of tsubst_decl for the case when T is a TEMPLATE_DECL. */
14619 static tree
14622 {
14623 /* We can get here when processing a member function template,
14624 member class template, or template template parameter. */
14627 tree spec;
14628 tree tmpl_args;
14630 tree r;
14634 {
14635 /* Template template parameter is treated here. */
14639 /* If we get a real template back, return it. This can happen in
14640 the context of most_specialized_partial_spec. */
14643 else
14644 /* The new TEMPLATE_DECL was built in
14645 reduce_template_parm_level. */
14648 }
14651 {
14652 /* We might already have an instance of this template.
14653 The ARGS are for the surrounding class type, so the
14654 full args contain the tsubst'd args for the context,
14655 plus the innermost args from the template decl. */
14659 /* Because this is a template, the arguments will still be
14660 dependent, even after substitution. If
14661 PROCESSING_TEMPLATE_DECL is not set, the dependency
14662 predicates will short-circuit. */
14670 /* If this is a default template template argument,
14671 tsubst might not have changed anything. */
14678 {
14680 /* Type partial instantiations are stored as the type by
14681 lookup_template_class_1, not here as the template. */
14686 }
14687 }
14689 /* Make a new template decl. It will be similar to the
14690 original, but will record the current template arguments.
14691 We also create a new function declaration, which is just
14692 like the old one, but points to this new template, rather
14693 than the old one. */
14698 // Build new template info linking to the original template decl.
14700 {
14703 }
14704 else
14707 /* The template parameters for this new template are all the
14708 template parameters for the old template, except the
14709 outermost level of parameters. */
14712 = current_template_parms
14713 = (lambda_tparms
14714 ? lambda_tparms
14716 complain));
14724 else
14725 {
14727 {
14730 }
14734 else
14736 }
14742 {
14743 /* For a partial specialization, we need to keep pointing to
14744 the primary template. */
14746 {
14749 }
14753 }
14755 {
14758 }
14759 else
14760 {
14762 /* Set DECL_TI_ARGS to the full set of template arguments,
14763 which tsubst_function_decl / tsubst_decl didn't do due to
14764 use_spec_table=false. */
14767 }
14774 {
14775 /* Propagate module information from the decl. */
14778 /* If this is a constrained template, the above tsubst of
14779 inner can find the unconstrained template, which may have
14780 come from an import. This is ok, because we don't
14781 register this instantiation (see below). */
14783 || (TEMPLATE_PARMS_CONSTRAINTS
14785 }
14794 {
14795 /* Record this non-type partial instantiation. */
14796 /* FIXME we'd like to always register the TEMPLATE_DECL, or always
14797 the DECL_TEMPLATE_RESULT, but it seems the modules code relies
14798 on this current behavior. */
14801 else
14803 }
14806 }
14808 /* True if FN is the op() for a lambda in an uninstantiated template. */
14810 bool
14812 {
14817 }
14819 /* True if FN is the substitution (via tsubst_lambda_expr) of a function for
14820 which the above is true. */
14822 bool
14824 {
14830 }
14832 /* Return the LAMBDA_EXPR from which T was ultimately regenerated.
14833 If T is not a regenerated LAMBDA_EXPR, return T. */
14835 tree
14837 {
14841 }
14843 /* Return the set of template arguments used to regenerate the lambda T
14844 from its most general lambda. */
14846 tree
14848 {
14854 else
14856 }
14858 /* We're instantiating a variable from template function TCTX. Return the
14859 corresponding current enclosing scope. We can match them up using
14860 DECL_SOURCE_LOCATION because lambdas only ever have one source location, and
14861 the DECL_SOURCE_LOCATION for a function instantiation is updated to match
14862 the template definition in regenerate_decl_from_template. */
14864 static tree
14866 {
14869 /* We shouldn't ever need to do this for other artificial functions. */
14876 }
14878 /* Substitute the ARGS into the T, which is a _DECL. Return the
14879 result of the substitution. Issue error and warning messages under
14880 control of COMPLAIN. The flag USE_SPEC_TABLE controls if we look up
14881 and insert into the specializations table or if we can assume it's
14882 the caller's responsibility; this is used by instantiate_template
14883 to avoid doing some redundant work. */
14885 static tree
14888 {
14889 #define RETURN(EXP) do { r = (EXP); goto out; } while(0)
14890 location_t saved_loc;
14898 /* Set the filename and linenumber to improve error-reporting. */
14903 {
14912 use_spec_table);
14916 {
14924 {
14925 /* If there is a local specialization that isn't a
14926 parameter pack, it means that we're doing a "simple"
14927 substitution from inside tsubst_pack_expansion. Just
14928 return the local specialization (which will be a single
14929 parm). */
14936 /* Expand the TYPE_PACK_EXPANSION that provides the types for
14937 the parameters in this function parameter pack. */
14941 {
14944 /* Zero-length parameter packs are boring. Just substitute
14945 into the chain. */
14949 }
14950 else
14951 {
14952 /* All we did was update the type. Make a note of that. */
14955 }
14956 }
14958 /* Loop through all of the parameters we'll build. When T is
14959 a function parameter pack, LEN is the number of expanded
14960 types in EXPANDED_TYPES; otherwise, LEN is 1. */
14963 {
14970 /* We're on the Ith parameter of the function parameter
14971 pack. */
14972 {
14973 /* Get the Ith type. */
14976 /* Rename the parameter to include the index. */
14979 }
14981 /* We're dealing with a normal parameter. */
14989 {
14992 else
14995 }
15006 /* Keep track of the first new parameter we
15007 generate. That's what will be returned to the
15008 caller. */
15012 /* Build a proper chain of parameters when substituting
15013 into a function parameter pack. */
15016 }
15018 /* If cp_unevaluated_operand is set, we're just looking for a
15019 single dummy parameter, so don't keep going. */
15024 /* FIRST_R contains the start of the chain we've built. */
15026 }
15030 {
15037 {
15038 /* This field is a lambda capture pack. Return a TREE_VEC of
15039 the expanded fields to instantiate_class_template_1. */
15043 {
15046 }
15047 else
15048 {
15049 /* All we did was update the type. Make a note of that. */
15052 }
15053 }
15056 {
15059 {
15063 }
15073 /* For bit-fields, DECL_BIT_FIELD_REPRESENTATIVE gives the
15074 number of bits. */
15079 {
15080 /* Set up DECL_TEMPLATE_INFO so that we can get at the
15081 NSDMI in perform_member_init. Still set DECL_INITIAL
15082 so that we know there is one. */
15087 }
15088 /* We don't have to set DECL_CONTEXT here; it is set by
15089 finish_member_declaration. */
15098 }
15102 }
15106 /* We reach here only for member using decls. We also need to check
15107 uses_template_parms because DECL_DEPENDENT_P is not set for a
15108 using-declaration that designates a member of the current
15109 instantiation (c++/53549). */
15112 {
15113 /* True iff this using-decl was written as a pack expansion
15114 (and a pack appeared in its scope or name). If a pack
15115 appeared in both, we expand the packs separately and
15116 manually merge them. */
15121 {
15124 in_decl);
15126 }
15127 else
15133 {
15137 {
15140 }
15144 }
15145 else
15153 {
15155 {
15160 }
15162 }
15170 {
15179 {
15182 }
15186 }
15190 }
15191 else
15192 {
15195 }
15200 {
15211 {
15212 /* If this is the canonical decl, we don't have to
15213 mess with instantiations, and often we can't (for
15214 typename, template type parms and such). Note that
15215 TYPE_NAME is not correct for the above test if
15216 we've copied the type for a typedef. */
15222 }
15224 /* Check to see if we already have the specialization we
15225 need. */
15231 {
15234 {
15236 complain,
15239 /* The context and type of an injected-class-name are
15240 the same, so we don't need to substitute both. */
15242 /* If CTX is unchanged, then T is in fact the
15243 specialization we want. That situation occurs when
15244 referencing a static data member within in its own
15245 class. We can use pointer equality, rather than
15246 same_type_p, because DECL_CONTEXT is always
15247 canonical... */
15249 /* ... unless T is a member template; in which
15250 case our caller can be willing to create a
15251 specialization of that template represented
15252 by T. */
15256 }
15259 {
15262 {
15269 }
15270 else
15272 }
15273 }
15274 else
15275 {
15277 /* Subsequent calls to pushdecl will fill this in. */
15279 /* A local variable. */
15281 /* Unless this is a reference to a static variable from an
15282 enclosing function, in which case we need to fill it in now. */
15284 {
15288 }
15290 }
15291 /* If we already have the specialization we need, there is
15292 nothing more to do. */
15294 {
15297 }
15299 /* Create a new node for the specialization we need. */
15301 {
15304 else
15314 /* Substituting the type might have recursively instantiated this
15315 same alias (c++/86171). */
15318 {
15321 }
15322 }
15327 {
15331 {
15332 /* It may seem that this case cannot occur, since:
15334 typedef void f();
15335 void g() { f x; }
15337 declares a function, not a variable. However:
15339 typedef void f();
15340 template <typename T> void g() { T t; }
15341 template void g<f>();
15343 is an attempt to declare a variable with function
15344 type. */
15346 /* R is not yet sufficiently initialized, so we
15347 just use its name. */
15350 }
15352 /* Wait until cp_finish_decl to set this again, to handle
15353 circular dependency (template/instantiate6.C). */
15358 {
15360 /* If the DECL_VALUE_EXPR is converted to the declared type,
15361 preserve the identity so that gimplify_type_sizes works. */
15367 {
15370 }
15379 else
15383 }
15387 }
15393 /* Clear out the mangled name and RTL for the instantiation. */
15399 /* The initializer must not be expanded until it is required;
15400 see [temp.inst]. */
15404 {
15410 /* Possibly limit visibility based on template args. */
15413 {
15417 }
15419 }
15422 {
15423 /* A static data member declaration is always marked
15424 external when it is declared in-class, even if an
15425 initializer is present. We mimic the non-template
15426 processing here. */
15435 }
15436 else
15437 {
15442 }
15451 /* Preserve a typedef that names a type. */
15453 {
15457 /* common_handle_aligned_attribute doesn't apply the alignment
15458 to DECL_ORIGINAL_TYPE. */
15462 }
15465 }
15470 }
15471 #undef RETURN
15473 out:
15474 /* Restore the file and line information. */
15478 }
15480 /* Substitute into the complete parameter type list PARMS. */
15482 tree
15484 tree args,
15485 tsubst_flags_t complain,
15486 tree in_decl)
15487 {
15489 }
15491 /* Substitute into the ARG_TYPES of a function type.
15492 If END is a TREE_CHAIN, leave it and any following types
15493 un-substituted. */
15495 static tree
15497 tree args,
15498 tree end,
15499 tsubst_flags_t complain,
15500 tree in_decl)
15501 {
15510 {
15511 /* For a pack expansion, perform substitution on the
15512 entire expression. Later on, we'll handle the arguments
15513 one-by-one. */
15518 /* So that we'll spin through the parameters, one by one. */
15520 else
15521 {
15522 /* We only partially substituted into the parameter
15523 pack. Our type is TYPE_PACK_EXPANSION. */
15526 }
15527 }
15528 else
15531 /* Check if a substituted type is erroneous before substituting into
15532 the rest of the chain. */
15534 {
15541 {
15543 {
15547 }
15549 }
15550 }
15552 /* We do not substitute into default arguments here. The standard
15553 mandates that they be instantiated only when needed, which is
15554 done in build_over_call. */
15557 /* Except that we do substitute default arguments under tsubst_lambda_expr,
15558 since the new op() won't have any associated template arguments for us
15559 to refer to later. */
15571 {
15575 /* Do array-to-pointer, function-to-pointer conversion, and ignore
15576 top-level qualifiers as required. */
15580 {
15581 /* We've instantiated a template before its default arguments
15582 have been parsed. This can happen for a nested template
15583 class, and is not an error unless we require the default
15584 argument in a call of this function. */
15585 remaining_arg_types
15588 remaining_arg_types);
15589 }
15590 else
15591 remaining_arg_types
15593 }
15596 }
15598 /* Substitute into a FUNCTION_TYPE or METHOD_TYPE. This routine does
15599 *not* handle the exception-specification for FNTYPE, because the
15600 initial substitution of explicitly provided template parameters
15601 during argument deduction forbids substitution into the
15602 exception-specification:
15604 [temp.deduct]
15606 All references in the function type of the function template to the
15607 corresponding template parameters are replaced by the specified tem-
15608 plate argument values. If a substitution in a template parameter or
15609 in the function type of the function template results in an invalid
15610 type, type deduction fails. [Note: The equivalent substitution in
15611 exception specifications is done only when the function is instanti-
15612 ated, at which point a program is ill-formed if the substitution
15613 results in an invalid type.] */
15615 static tree
15617 tree args,
15618 tsubst_flags_t complain,
15619 tree in_decl)
15620 {
15621 tree return_type;
15624 /* The TYPE_CONTEXT is not used for function/method types. */
15627 /* DR 1227: Mixing immediate and non-immediate contexts in deduction
15628 failure. */
15632 {
15633 /* Substitute the argument types. */
15645 {
15646 /* DR 1207: 'this' is in scope in the trailing return type. */
15648 }
15650 /* Substitute the return type. */
15654 {
15657 }
15658 }
15659 else
15660 /* Substitute the return type. */
15665 /* DR 486 clarifies that creation of a function type with an
15666 invalid return type is a deduction failure. */
15669 {
15671 {
15674 else
15676 }
15678 }
15681 {
15682 /* Substitute the argument types. */
15687 }
15689 /* Construct a new type node and return it. */
15692 }
15694 /* FNTYPE is a FUNCTION_TYPE or METHOD_TYPE. Substitute the template
15695 ARGS into that specification, and return the substituted
15696 specification. If there is no specification, return NULL_TREE. */
15698 static tree
15700 tree args,
15701 tsubst_flags_t complain,
15702 tree in_decl,
15704 {
15705 tree specs;
15706 tree new_specs;
15711 {
15712 /* A noexcept-specifier. */
15717 {
15718 /* Defer instantiation of noexcept-specifiers to avoid
15719 excessive instantiations (c++/49107). */
15722 {
15723 /* We already partially instantiated this member template,
15724 so combine the new args with the old. */
15729 }
15730 else
15731 {
15734 }
15735 }
15736 else
15737 {
15739 {
15741 args);
15743 }
15745 }
15747 /* We've instantiated a template before a noexcept-specifier
15748 contained therein has been parsed. This can happen for
15749 a nested template class:
15751 struct S {
15752 template<typename> struct B { B() noexcept(...); };
15753 struct A : B<int> { ... use B() ... };
15754 };
15756 where completing B<int> will trigger instantiating the
15757 noexcept, even though we only parse it at the end of S. */
15759 {
15762 }
15763 }
15765 {
15768 else
15770 {
15771 tree spec;
15776 {
15777 /* Expand the pack expansion type. */
15780 in_decl);
15786 else
15787 {
15788 /* We're substituting into a member template, so
15789 we got a TYPE_PACK_EXPANSION back. Add that
15790 expansion and move on. */
15794 expanded_specs,
15795 complain);
15798 }
15799 }
15802 {
15805 else
15810 complain);
15811 }
15814 }
15815 }
15817 }
15819 /* Substitute through a TREE_LIST of types or expressions, handling pack
15820 expansions. */
15822 tree
15824 {
15831 ;
15833 {
15837 }
15840 else
15848 ;
15850 {
15854 }
15857 else
15864 ;
15869 else
15880 /* Determine the number of arguments. */
15882 {
15885 }
15888 else
15892 {
15900 else
15902 }
15905 }
15907 /* Take the tree structure T and replace template parameters used
15908 therein with the argument vector ARGS. IN_DECL is an associated
15909 decl for diagnostics. If an error occurs, returns ERROR_MARK_NODE.
15910 Issue error and warning messages under control of COMPLAIN. Note
15911 that we must be relatively non-tolerant of extensions here, in
15912 order to preserve conformance; if we allow substitutions that
15913 should not be allowed, we may allow argument deductions that should
15914 not succeed, and therefore report ambiguous overload situations
15915 where there are none. In theory, we could allow the substitution,
15916 but indicate that it should have failed, and allow our caller to
15917 make sure that the right thing happens, but we don't try to do this
15918 yet.
15920 This function is used for dealing with types, decls and the like;
15921 for expressions, use tsubst_expr or tsubst_copy. */
15923 tree
15925 {
15960 /* Reuse typedefs. We need to do this to handle dependent attributes,
15961 such as attribute aligned. */
15964 {
15968 {
15969 /* DECL represents an alias template and we want to
15970 instantiate it. */
15974 }
15978 {
15982 }
15987 else
15988 /* The typedef is from a non-template context. */
15992 {
15994 r = cp_build_qualified_type
15998 }
15999 else
16000 {
16001 /* We don't have an instantiation yet, so drop the typedef. */
16006 }
16007 }
16024 {
16028 /* Fall through. */
16054 {
16059 /* Fix up type of the magic NOP_EXPR with TREE_SIDE_EFFECTS if
16060 needed. */
16066 /* If we're in a partial instantiation, preserve the magic NOP_EXPR
16067 with TREE_SIDE_EFFECTS that indicates this is not an integral
16068 constant expression. */
16071 {
16074 }
16077 }
16081 {
16089 else
16091 }
16092 /* Fall through. */
16096 {
16110 {
16113 /* See through ARGUMENT_PACK_SELECT arguments. */
16116 }
16121 {
16123 /* If ARG is an argument pack, we don't actually want to
16124 perform a substitution here, because substitutions
16125 for argument packs are only done
16126 element-by-element. We can get to this point when
16127 substituting the type of a non-type template
16128 parameter pack, when that type actually contains
16129 template parameter packs from an outer template, e.g.,
16131 template<typename... Types> struct A {
16132 template<Types... Values> struct B { };
16133 }; */
16137 {
16140 /* When building concept checks for the purpose of
16141 deducing placeholders, we can end up with wildcards
16142 where types are expected. Adjust this to the deduced
16143 value. */
16151 return cp_build_qualified_type
16153 }
16155 {
16156 /* We are processing a type constructed from a
16157 template template parameter. */
16168 /* Consider this code:
16170 template <template <class> class Template>
16171 struct Internal {
16172 template <class Arg> using Bind = Template<Arg>;
16173 };
16175 template <template <class> class Template, class Arg>
16176 using Instantiate = Template<Arg>; //#0
16178 template <template <class> class Template,
16179 class Argument>
16180 using Bind =
16181 Instantiate<Internal<Template>::template Bind,
16182 Argument>; //#1
16184 When #1 is parsed, the
16185 BOUND_TEMPLATE_TEMPLATE_PARM representing the
16186 parameter `Template' in #0 matches the
16187 UNBOUND_CLASS_TEMPLATE representing the argument
16188 `Internal<Template>::template Bind'; We then want
16189 to assemble the type `Bind<Argument>' that can't
16190 be fully created right now, because
16191 `Internal<Template>' not being complete, the Bind
16192 template cannot be looked up in that context. So
16193 we need to "store" `Bind<Argument>' for later
16194 when the context of Bind becomes complete. Let's
16195 store that in a TYPENAME_TYPE. */
16199 argvec),
16200 typename_type,
16201 complain);
16203 /* We can get a TEMPLATE_TEMPLATE_PARM here when we
16204 are resolving nested-types in the signature of a
16205 member function templates. Otherwise ARG is a
16206 TEMPLATE_DECL and is the real template to be
16207 instantiated. */
16215 complain);
16216 return cp_build_qualified_type
16218 }
16221 else
16222 /* TEMPLATE_PARM_INDEX. */
16224 }
16227 /* This can happen during the attempted tsubst'ing in
16228 unify. This means that we don't yet have any information
16229 about the template parameter in question. */
16232 /* Early in template argument deduction substitution, we don't
16233 want to reduce the level of 'auto', or it will be confused
16234 with a normal template parm in subsequent deduction.
16235 Similarly, don't reduce the level of template parameters to
16236 avoid mismatches when deducing their types. */
16240 /* If we get here, we must have been looking at a parm for a
16241 more deeply nested template. Make a new version of this
16242 template parameter, but with a lower level. */
16245 {
16250 {
16253 }
16259 /* Cache lowering a type parameter or a simple template
16260 template parameter. */
16264 {
16276 /* Propagate constraints on placeholders since they are
16277 only instantiated during satisfaction. */
16282 else
16284 }
16292 {
16294 /* We might need to substitute into the types of non-type
16295 template parameters. This also lowers the level of
16296 the ttp appropriately. */
16309 }
16312 /* OK, now substitute the type of the non-type parameter. We
16313 couldn't do it earlier because it might be an auto parameter,
16314 and we wouldn't need to if we had an argument. */
16323 }
16326 }
16332 /* We should never be tsubsting a binfo. */
16336 /* A vector of template arguments. */
16342 {
16346 /* [temp.deduct]
16348 Type deduction may fail for any of the following
16349 reasons:
16351 -- Attempting to create a pointer to reference type.
16352 -- Attempting to create a reference to a reference type or
16353 a reference to void.
16355 Core issue 106 says that creating a reference to a reference
16356 during instantiation is no longer a cause for failure. We
16357 only enforce this check in strict C++98 mode. */
16361 {
16364 /* We keep track of the last time we issued this error
16365 message to avoid spewing a ton of messages during a
16366 single bad template instantiation. */
16369 {
16374 else
16377 }
16380 }
16384 {
16386 {
16389 type);
16390 else
16392 type);
16393 }
16395 }
16397 {
16401 }
16403 /* In C++0x, during template argument substitution, when there is an
16404 attempt to create a reference to a reference type, reference
16405 collapsing is applied as described in [14.3.1/4 temp.arg.type]:
16407 "If a template-argument for a template-parameter T names a type
16408 that is a reference to a type A, an attempt to create the type
16409 'lvalue reference to cv T' creates the type 'lvalue reference to
16410 A,' while an attempt to create the type type rvalue reference to
16411 cv T' creates the type T"
16412 */
16413 r = cp_build_reference_type
16416 else
16421 /* Will this ever be needed for TYPE_..._TO values? */
16425 }
16427 {
16430 {
16431 /* [temp.deduct]
16433 Type deduction may fail for any of the following
16434 reasons:
16436 -- Attempting to create "pointer to member of T" when T
16437 is not a class type. */
16441 }
16443 {
16447 }
16449 {
16453 }
16456 {
16457 /* The type of the implicit object parameter gets its
16458 cv-qualifiers from the FUNCTION_TYPE. */
16459 tree memptr;
16460 tree method_type
16465 complain);
16466 }
16467 else
16470 complain);
16471 }
16474 {
16475 tree fntype;
16476 tree specs;
16481 /* Substitute the exception specification. */
16489 }
16491 {
16496 /* As an optimization, we avoid regenerating the array type if
16497 it will obviously be the same as T. */
16501 /* These checks should match the ones in create_array_type_for_decl.
16503 [temp.deduct]
16505 The deduction may fail for any of the following reasons:
16507 -- Attempting to create an array with an element type that
16508 is void, a function type, or a reference type, or [DR337]
16509 an abstract class type. */
16515 {
16519 }
16532 {
16535 }
16538 }
16541 {
16544 {
16547 in_decl);
16552 {
16557 }
16559 }
16560 else
16573 {
16577 }
16579 {
16580 /* Normally, make_typename_type does not require that the CTX
16581 have complete type in order to allow things like:
16583 template <class T> struct S { typename S<T>::X Y; };
16585 But, such constructs have already been resolved by this
16586 point, so here CTX really should have complete type, unless
16587 it's a partial instantiation. */
16590 }
16592 /* FIXME: TYPENAME_IS_CLASS_P conflates 'class' vs 'struct' vs 'union'
16593 tags. TYPENAME_TYPE should probably remember the exact tag that
16594 was written. */
16595 enum tag_types tag_type
16605 {
16608 }
16611 {
16613 {
16617 else
16619 }
16621 {
16625 else
16627 }
16628 }
16630 return cp_build_qualified_type
16632 }
16635 {
16647 }
16650 {
16651 tree type;
16665 complain);
16666 }
16669 {
16670 tree type;
16687 else
16688 {
16692 /* In a template ~id could be either a complement expression
16693 or an unqualified-id naming a destructor; if instantiating
16694 it produces an expression, it's not an id-expression or
16695 member access. */
16698 }
16703 }
16706 {
16710 else
16717 }
16736 /* We should use one of the expression tsubsts for these codes. */
16742 }
16743 }
16745 /* Convenience wrapper over tsubst for substituting into the LHS
16746 of the :: scope resolution operator. */
16748 static tree
16750 {
16753 }
16755 /* Convenience wrapper over tsubst for substituting into an id-expression
16756 without resolving its terminal name. */
16758 static tree
16760 {
16762 }
16764 /* OLDFNS is a lookup set of member functions from some class template, and
16765 NEWFNS is a lookup set of member functions from NEWTYPE, a specialization
16766 of that class template. Return the subset of NEWFNS which are
16767 specializations of a function from OLDFNS. */
16769 static tree
16771 {
16772 /* Record all member functions from the old lookup set OLDFNS into
16773 VISIBLE_SET. */
16777 {
16779 {
16780 /* Imprecisely handle dependent using-decl by keeping all members
16781 in the new lookup set that are defined in a base class, i.e.
16782 members that could plausibly have been introduced by this
16783 dependent using-decl.
16784 FIXME: Track which members are introduced by a dependent
16785 using-decl precisely, perhaps by performing another lookup
16786 from the substituted USING_DECL_SCOPE. */
16789 }
16790 else
16792 }
16794 /* Returns true iff (a less specialized version of) FN appeared in
16795 the old lookup set OLDFNS. */
16798 /* FN is a member function from a base class, introduced via a
16799 using-decl; if it might have been introduced by a dependent
16800 using-decl then just conservatively keep it, otherwise look
16801 in the old lookup set for FN exactly. */
16804 /* FN is a member function template from the current class;
16805 look in the old lookup set for the TEMPLATE_DECL from which
16806 it was specialized. */
16808 else
16809 /* FN is a non-template member function from the current class;
16810 look in the old lookup set for the FUNCTION_DECL from which
16811 it was specialized. */
16814 };
16819 {
16822 }
16826 /* Filter out from NEWFNS the member functions that weren't
16827 previously visible according to OLDFNS. */
16832 {
16834 filtered_size++;
16835 }
16841 }
16843 /* tsubst a BASELINK. OBJECT_TYPE, if non-NULL, is the type of the
16844 expression on the left-hand side of the "." or "->" operator. We
16845 only do the lookup if we had a dependent BASELINK. Otherwise we
16846 adjust it onto the instantiated heirarchy. */
16848 static tree
16851 {
16863 {
16870 }
16878 {
16883 /* See maybe_dependent_member_ref. */
16885 {
16888 template_args);
16891 }
16894 /* Treat as-if non-dependent below. */
16899 complain);
16901 {
16902 /* Filter out from the new lookup set those functions which didn't
16903 appear in the original lookup set (in a less specialized form).
16904 This is needed to preserve the consistency of member lookup
16905 performed in an incomplete-class context, within which
16906 later-declared members ought to remain invisible. */
16909 binfo_type);
16911 }
16914 {
16920 }
16923 }
16924 else
16925 {
16926 /* We're going to overwrite pieces below, make a duplicate. */
16930 {
16931 /* The decl we found was from non-dependent scope, but we still need
16932 to update the binfos for the instantiated qualifying_scope. */
16936 }
16937 }
16939 /* If lookup found a single function, mark it as used at this point.
16940 (If lookup found multiple functions the one selected later by
16941 overload resolution will be marked as used at that point.) */
16943 {
16949 /* We might have instantiated an auto function. */
16951 }
16954 {
16955 /* Add back the template arguments, if present. */
16960 /* Update the conversion operator type. */
16962 }
16968 {
16970 qualifying_scope,
16971 object_type);
16973 /* We need to call adjust_result_of_qualified_name_lookup in case the
16974 destructor names a base class, but we unset BASELINK_QUALIFIED_P
16975 so that we still get virtual function binding. */
16977 }
16980 }
16982 /* Like tsubst_expr for a SCOPE_REF, given by QUALIFIED_ID. DONE is
16983 true if the qualified-id will be a postfix-expression in-and-of
16984 itself; false if more of the postfix-expression follows the
16985 QUALIFIED_ID. ADDRESS_P is true if the qualified-id is the operand
16986 of "&". */
16988 static tree
16992 {
16993 tree expr;
16994 tree scope;
16995 tree name;
16997 tree template_args;
17002 /* Figure out what name to look up. */
17005 {
17014 }
17015 else
17016 {
17019 }
17021 /* Substitute into the qualifying scope. When there are no ARGS, we
17022 are just trying to simplify a non-dependent expression. In that
17023 case the qualifying scope may be dependent, and, in any case,
17024 substituting will not help. */
17027 {
17030 }
17031 else
17035 {
17037 /* We built one in tsubst_baselink. */
17039 else
17040 {
17043 template_args);
17045 QUALIFIED_NAME_IS_TEMPLATE
17047 }
17050 }
17053 {
17055 {
17056 /* A BIT_NOT_EXPR is used to represent a destructor. */
17058 {
17062 }
17063 else
17066 }
17067 else
17071 {
17073 {
17077 }
17079 }
17080 }
17083 {
17087 /* Remember that there was a reference to this entity. */
17090 }
17093 {
17099 }
17102 {
17103 /* We may be repeating a check already done during parsing, but
17104 if it was well-formed and passed then, it will pass again
17105 now, and if it didn't, we wouldn't have got here. The case
17106 we want to catch is when we couldn't tell then, and can now,
17107 namely when templ prior to substitution was an
17108 identifier. */
17114 complain);
17115 else
17117 }
17123 {
17124 expr = (adjust_result_of_qualified_name_lookup
17126 expr = (finish_qualified_id_expr
17130 }
17132 /* Expressions do not generally have reference type. */
17134 /* However, if we're about to form a pointer-to-member, we just
17135 want the referenced member referenced. */
17145 }
17147 /* tsubst the initializer for a VAR_DECL. INIT is the unsubstituted
17148 initializer, DECL is the substituted VAR_DECL. Other arguments are as
17149 for tsubst. */
17151 static tree
17154 {
17163 {
17165 {
17167 {
17172 }
17173 }
17175 {
17176 /* If we had an initializer but it
17177 instantiated to nothing,
17178 value-initialize the object. This will
17179 only occur when the initializer was a
17180 pack expansion where the parameter packs
17181 used in that expansion were of length
17182 zero. */
17188 }
17189 }
17192 }
17194 /* If T is a reference to a dependent member of the current instantiation C and
17195 we are trying to refer to that member in a partial instantiation of C,
17196 return a SCOPE_REF; otherwise, return NULL_TREE.
17198 This can happen when forming a C++17 deduction guide, as in PR96199. */
17200 static tree
17202 tree in_decl)
17203 {
17220 {
17229 complain);
17230 }
17235 {
17241 }
17244 {
17247 /* The TYPE_DECL for a typename has DECL_CONTEXT of the typename
17248 scope, but it doesn't need to be rewritten again. */
17252 }
17256 else
17259 }
17261 /* Helper function for tsubst_omp_clauses, used for instantiation of
17262 OMP_CLAUSE_DECL of clauses. */
17264 static tree
17267 {
17271 /* Handle OpenMP iterators. */
17275 {
17276 tree ret;
17279 else
17280 {
17284 {
17298 }
17302 }
17306 }
17308 /* Handle an OpenMP array section represented as a TREE_LIST (or
17309 OMP_CLAUSE_DOACROSS_KIND). An OMP_CLAUSE_DOACROSS (with a depend
17310 kind of OMP_CLAUSE_DOACROSS_SINK) can also be represented as a
17311 TREE_LIST. We can handle it exactly the same as an array section
17312 (purpose, value, and a chain), even though the nomenclature
17313 (low_bound, length, etc) is different. */
17315 {
17316 tree low_bound
17329 }
17331 /* Undo convert_from_reference tsubst_expr could have called. */
17337 }
17339 /* Like tsubst_copy, but specifically for OpenMP clauses. */
17341 static tree
17344 {
17350 {
17356 {
17359 {
17365 }
17366 /* FALLTHRU */
17396 /* FALLTHRU */
17430 {
17433 {
17440 }
17441 else
17443 }
17470 {
17473 }
17478 else
17509 }
17512 {
17529 /* tsubst_expr on SCOPE_REF results in returning
17530 finish_non_static_data_member result. Undo that here. */
17534 {
17539 {
17543 CASE_CONVERT:
17552 /* FALLTHRU */
17556 }
17557 }
17563 {
17566 {
17569 }
17570 }
17574 }
17575 }
17579 {
17584 {
17587 }
17588 }
17590 }
17592 /* Like tsubst_expr, but unshare TREE_LIST nodes. */
17594 static tree
17596 tree in_decl)
17597 {
17598 #define RECUR(t) tsubst_copy_asm_operands (t, args, complain, in_decl)
17616 {
17619 else
17620 {
17624 }
17625 }
17630 #undef RECUR
17631 }
17633 /* Used to temporarily communicate the list of #pragma omp parallel
17634 clauses to #pragma omp for instantiation if they are combined
17635 together. */
17640 cp_decomp *);
17642 /* Substitute one OMP_FOR iterator. */
17644 static bool
17648 {
17649 #define RECUR(NODE) \
17650 tsubst_stmt ((NODE), args, complain, in_decl)
17662 {
17665 {
17670 {
17679 else
17681 {
17683 {
17689 }
17692 }
17693 }
17694 }
17698 }
17700 {
17701 /* We need to jump through some hoops to handle declarations in the
17702 init-statement, since we might need to handle auto deduction,
17703 but we need to keep control of initialization. */
17707 }
17708 else
17709 {
17711 {
17714 {
17718 {
17722 CASE_CONVERT:
17730 {
17733 }
17734 /* FALLTHRU */
17738 }
17739 }
17740 }
17741 else
17743 }
17745 {
17751 }
17752 else
17756 {
17762 NULL_TREE);
17763 else
17765 }
17768 {
17776 {
17781 }
17784 }
17794 {
17796 {
17797 /* Declare the variable, but don't let that initialize it. */
17802 }
17805 {
17809 {
17818 }
17819 else
17823 {
17828 }
17829 else
17833 }
17839 }
17842 {
17843 /* Declare and initialize the variable. */
17846 }
17848 {
17853 {
17855 {
17861 {
17864 /* Move lastprivate (decl) clause to OMP_FOR_CLAUSES. */
17869 }
17872 {
17874 decl);
17876 }
17879 {
17881 decl);
17883 }
17884 else
17886 }
17889 }
17891 {
17894 ? OMP_CLAUSE_LASTPRIVATE
17899 {
17902 }
17903 }
17904 }
17907 {
17911 }
17912 else
17916 {
17927 {
17935 }
17936 else
17942 {
17948 }
17952 {
17960 }
17961 else
17967 }
17976 #undef RECUR
17977 }
17979 /* Helper function of tsubst_expr, find OMP_TEAMS inside
17980 of OMP_TARGET's body. */
17982 static tree
17984 {
17987 {
17996 }
17998 }
18000 /* Helper function for tsubst_expr. For decomposition declaration
18001 artificial base DECL, which is tsubsted PATTERN_DECL, tsubst
18002 also the corresponding decls representing the identifiers
18003 of the decomposition declaration. Return DECL if successful
18004 or error_mark_node otherwise, set *FIRST to the first decl
18005 in the list chained through DECL_CHAIN and *CNT to the number
18006 of such decls. */
18008 static tree
18011 {
18016 decl2
18021 {
18023 {
18026 }
18038 else
18039 {
18043 }
18050 {
18053 }
18054 else
18056 }
18059 }
18061 /* Return the proper local_specialization for init-capture pack DECL. */
18063 static tree
18065 {
18066 /* We handle normal pack captures by forwarding to the specialization of the
18067 captured parameter. We can't do that for pack init-captures; we need them
18068 to have their own local_specialization. We created the individual
18069 VAR_DECLs (if any) under build_capture_proxy, and we need to collect them
18070 when we process the DECL_EXPR for the pack init-capture in the template.
18071 So, how do we find them? We don't know the capture proxy pack when
18072 building the individual resulting proxies, and we don't know the
18073 individual proxies when instantiating the pack. What we have in common is
18074 the FIELD_DECL.
18076 So...when we instantiate the FIELD_DECL, we stick the result in
18077 local_specializations. Then at the DECL_EXPR we look up that result, see
18078 how many elements it has, synthesize the names, and look them up. */
18092 {
18097 }
18099 {
18104 else
18106 }
18108 }
18110 /* T is an operand of a template tree being substituted. Return whether
18111 T is dependent such that we should suppress some warnings that would
18112 make sense if the substituted expression were written directly, like
18113 template <int I> bool f() { return I == 2; }
18114 We don't want to warn when instantiating f that comparing two constants
18115 always has the same value.
18117 This is a more limited concept of dependence than instantiation-dependent;
18118 here we don't care whether substitution could fail. */
18120 static bool
18122 {
18131 }
18133 /* A superset of tsubst_expr that also handles statement trees. */
18135 static tree
18137 {
18138 #define RETURN(EXP) do { r = (EXP); goto out; } while(0)
18139 #define RECUR(NODE) \
18140 tsubst_stmt ((NODE), args, complain, in_decl)
18143 tree r;
18144 location_t loc;
18156 {
18158 {
18162 }
18181 else
18194 {
18199 }
18203 {
18205 tree init;
18211 {
18214 {
18218 {
18223 }
18225 }
18226 else
18227 {
18228 /* This is a non-dependent using-decl, and we'll have
18229 used the names it found during template parsing. We do
18230 not want to do the lookup again, because we might not
18231 find the things we found then. */
18234 /* We still need to push the bindings so that we can look up
18235 this name later. */
18238 }
18239 }
18242 {
18243 /* We're in tsubst_lambda_expr, we've already inserted a new
18244 capture proxy, so look it up and register it. */
18245 tree inst;
18247 {
18251 }
18253 {
18254 inst = (retrieve_local_specialization
18258 }
18259 else
18264 }
18271 /* Don't copy the old closure; we'll create a new one in
18272 tsubst_lambda_expr. */
18274 else
18275 {
18279 {
18280 /* By marking the declaration as instantiated, we avoid
18281 trying to instantiate it. Since instantiate_decl can't
18282 handle local variables, and since we've already done
18283 all that needs to be done, that's the right thing to
18284 do. */
18289 /* Anonymous aggregates are a special case. */
18292 {
18295 {
18299 }
18301 }
18306 {
18314 }
18315 else
18316 {
18331 {
18335 }
18340 const_init = (DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P
18343 /* In a non-template function, VLA type declarations are
18344 handled in grokdeclarator; for templates, handle them
18345 now. */
18349 {
18353 asmspec_tree
18357 }
18360 decomp);
18364 }
18365 }
18366 }
18369 }
18379 {
18383 }
18388 {
18389 /* Construct another range_for, if this is not a final
18390 substitution (for inside a generic lambda of a
18391 template). Otherwise convert to a regular for. */
18393 stmt = (processing_template_decl
18404 {
18408 }
18411 {
18418 }
18419 else
18420 {
18426 }
18432 }
18439 {
18443 }
18449 {
18453 }
18465 {
18471 }
18474 {
18475 /* We're partially instantiating a generic lambda, but the condition
18476 of the constexpr if is still dependent. Don't substitute into the
18477 branches now, just remember the template arguments. */
18485 }
18489 {
18494 }
18495 else
18496 {
18504 }
18510 {
18520 }
18528 else
18536 else
18557 {
18563 {
18568 }
18569 }
18573 {
18575 tree label;
18582 }
18588 /* Computed goto's must be tsubst'd into. On the other hand,
18589 non-computed gotos must not be; the identifier in question
18590 will have no binding. */
18592 else
18598 {
18615 }
18620 {
18625 }
18626 else
18627 {
18632 else
18639 else
18645 else
18647 }
18651 {
18655 {
18657 /* Prevent instantiate_decl from trying to instantiate
18658 this variable. We've already done all that needs to be
18659 done. */
18662 }
18667 }
18673 {
18674 /* Local classes are not independent templates; they are
18675 instantiated along with their containing function. And this
18676 way we don't have to deal with pushing out of one local class
18677 to instantiate a member of another local class. */
18678 /* Closures are handled by the LAMBDA_EXPR. */
18682 {
18683 /* This is a partial instantiation, try again when full. */
18686 }
18700 }
18704 {
18705 tree condition;
18716 }
18723 in_decl);
18745 {
18752 }
18768 {
18782 in_decl);
18784 {
18791 }
18802 any_range_for
18809 {
18818 }
18819 else
18824 else
18831 else
18832 {
18840 }
18843 t));
18845 }
18851 /* FALLTHRU */
18861 in_decl);
18863 {
18868 }
18869 else
18870 {
18874 }
18879 {
18881 "%<#pragma omp critical%> with %<hint%> clause requires "
18884 }
18895 {
18898 {
18903 }
18904 else
18905 {
18909 }
18911 }
18912 else
18914 OMP_CLAUSE_DEPEND_INVALID,
18923 ? C_ORT_ACC
18942 {
18945 /* For combined target teams, ensure the num_teams and
18946 thread_limit clause expressions are evaluated on the host,
18947 before entering the target construct. */
18956 {
18959 tf_none);
18966 OMP_CLAUSE_FIRSTPRIVATE);
18970 }
18971 }
19008 {
19012 }
19013 else
19025 /* FALLTHRU */
19043 {
19049 {
19052 }
19054 {
19058 {
19061 }
19066 }
19067 else
19068 {
19071 }
19076 }
19077 else
19078 {
19085 {
19088 }
19091 {
19096 {
19099 }
19101 {
19105 {
19108 }
19113 }
19114 else
19115 {
19118 }
19122 }
19123 else
19124 {
19128 }
19132 }
19136 {
19142 {
19146 {
19151 }
19155 }
19156 else
19157 {
19162 }
19163 }
19167 {
19171 }
19184 /* If the first operand was a statement, we're done with it. */
19189 complain));
19198 }
19201 out:
19204 #undef RECUR
19205 #undef RETURN
19206 }
19208 /* Instantiate the special body of the artificial DECL_OMP_DECLARE_REDUCTION
19209 function. For description of the body see comment above
19210 cp_parser_omp_declare_reduction_exprs. */
19212 static void
19214 {
19220 tree_stmt_iterator tsi;
19231 {
19238 /* tsubsting a local var_decl leaves DECL_CONTEXT null, as we
19239 expect to be pushing it. */
19251 }
19253 {
19273 }
19274 }
19276 /* T is a postfix-expression that is not being used in a function
19277 call. Return the substituted version of T. */
19279 static tree
19281 tsubst_flags_t complain,
19282 tree in_decl)
19283 {
19287 else
19291 }
19293 /* Subroutine of tsubst_lambda_expr: add the FIELD/INIT capture pair to the
19294 LAMBDA_EXPR_CAPTURE_LIST passed in LIST. Do deduction for a previously
19295 dependent init-capture. EXPLICIT_P is true if the original list had
19296 explicit captures. */
19298 static void
19300 tsubst_flags_t complain)
19301 {
19303 {
19306 {
19310 }
19317 }
19320 }
19322 /* T is a LAMBDA_EXPR. Generate a new LAMBDA_EXPR for the current
19323 instantiation context. Instantiating a pack expansion containing a lambda
19324 might result in multiple lambdas all based on the same lambda in the
19325 template. */
19327 tree
19329 {
19344 else
19355 {
19360 else
19372 {
19373 /* For a VLA, simply tsubsting the field type won't work, we need to
19374 go through add_capture again. XXX do we want to do this for all
19375 captures? */
19376 tree name = (get_identifier
19384 }
19391 {
19392 /* Remember these for when we've pushed local_specializations. */
19395 }
19401 {
19410 complain);
19411 }
19412 else
19413 {
19419 }
19420 }
19429 /* If we're pushed into another scope (PR105652), fix it. */
19434 /* Do this again now that LAMBDA_EXPR_EXTRA_SCOPE is set. */
19451 {
19454 }
19457 {
19460 }
19464 else
19465 {
19466 /* The body of a lambda-expression is not a subexpression of the
19467 enclosing expression. Parms are to have DECL_CHAIN tsubsted,
19468 which would be skipped if cp_unevaluated_operand. */
19469 cp_evaluated ev;
19471 /* Fix the type of 'this'. */
19475 tree inst = (oldtmpl
19480 {
19483 }
19489 /* Let finish_function set this. */
19495 else
19496 /* Still increment function_depth so that we don't GC in the
19497 middle of an expression. */
19507 /* Now record them for lookup_init_capture_pack. */
19510 {
19514 }
19520 {
19521 /* We might not partially instantiate some parts of the function, so
19522 copy these flags from the original template. */
19528 }
19530 /* [temp.deduct] A lambda-expression appearing in a function type or a
19531 template parameter is not considered part of the immediate context for
19532 the purposes of template argument deduction. */
19537 /* We already have a body block from start_lambda_function, we don't
19538 need another to confuse NRV (91217). */
19549 else
19552 /* The capture list was built up in reverse order; fix that now. */
19559 }
19561 out:
19567 }
19569 /* Subroutine of maybe_fold_fn_template_args. */
19571 static bool
19573 {
19576 {
19582 {
19585 }
19590 {
19594 }
19595 }
19598 }
19600 /* Try to do constant evaluation of any explicit template arguments in FN
19601 before overload resolution, to get any errors only once. Return true iff
19602 we didn't have any problems folding. */
19604 static bool
19606 {
19624 }
19626 /* Helper function for tsubst_expr CALL_EXPR and ARRAY_REF handling. */
19628 static void
19631 {
19634 {
19639 else
19640 {
19641 /* Expand the pack expansion and push each entry onto CALL_ARGS. */
19644 {
19649 {
19654 }
19655 }
19656 else
19657 /* A partial substitution. Add one entry. */
19659 }
19660 }
19661 }
19663 /* Like tsubst but deals with expressions and performs semantic
19664 analysis. */
19666 tree
19668 {
19669 #define RETURN(EXP) do { retval = (EXP); goto out; } while(0)
19670 #define RECUR(NODE) \
19671 tsubst_expr (NODE, args, complain, in_decl)
19674 location_t save_loc;
19683 /* N3276 decltype magic only applies to calls at the top level or on the
19684 right side of a comma. */
19688 /* This flag only applies to id-expressions at the top level, and
19689 controls resolution thereof. */
19698 {
19701 /* Fall through. */
19703 {
19704 tree decl;
19705 cp_id_kind idk;
19709 {
19712 }
19717 /* Look up the name. */
19720 /* By convention, expressions use ERROR_MARK_NODE to indicate
19721 failure, not NULL_TREE. */
19735 input_location);
19739 {
19743 }
19745 }
19748 {
19749 tree object;
19755 else
19764 {
19769 }
19772 {
19779 /* If we built a function concept check, return the underlying
19780 template-id. So we can evaluate it as a function call. */
19785 }
19788 {
19793 complain);
19797 }
19800 {
19803 }
19804 else
19816 {
19817 /* C++20 P0846: we can encounter an IDENTIFIER_NODE here when
19818 name lookup found nothing when parsing the template name. */
19821 }
19822 else
19824 }
19827 {
19831 {
19832 /* A type conversion to reference type will be enclosed in
19833 such an indirect ref, but the substitution of the cast
19834 will have also added such an indirect ref. */
19836 }
19837 else
19846 }
19849 {
19853 }
19856 {
19860 {
19865 }
19867 /* We'll pass this to convert_nontype_argument again, we don't need
19868 to actually perform any conversion here. */
19876 flags));
19877 }
19880 {
19886 }
19893 {
19894 tree type;
19908 {
19928 }
19931 }
19934 {
19938 }
19950 {
19953 }
19955 {
19959 }
19960 /* Fall through. */
19975 {
19982 }
19985 /* convert_like should have created an IMPLICIT_CONV_EXPR. */
19996 else
19998 in_decl);
20033 {
20034 /* If either OP0 or OP1 was value- or type-dependent, suppress
20035 warnings that depend on the range of the types involved. */
20049 tree r = build_x_binary_op
20051 op0,
20053 ? ERROR_MARK
20055 op1,
20057 ? ERROR_MARK
20066 }
20069 {
20077 }
20081 {
20086 }
20087 else
20101 {
20103 releasing_vec index_exp_list;
20106 tree r;
20112 else
20117 }
20125 {
20134 /* We only want to compute the number of arguments. */
20137 else
20144 {
20146 /* Set TREE_USED for the benefit of -Wunused. */
20150 }
20158 {
20163 else
20171 else
20176 }
20177 else
20179 }
20180 /* Fall through */
20183 {
20184 tree r;
20192 {
20193 /* When there are no ARGS, we are trying to evaluate a
20194 non-dependent expression from the parser. Trying to do
20195 the substitutions may not work. */
20198 }
20199 else
20200 {
20205 else
20209 }
20214 else
20219 {
20221 {
20223 {
20227 }
20228 else
20232 }
20234 }
20236 }
20239 {
20247 }
20261 {
20266 tree r = build_x_modify_expr
20270 /* TREE_NO_WARNING must be set if either the expression was
20271 parenthesized or it uses an operator such as >>= rather
20272 than plain assignment. In the former case, it was already
20273 set and must be copied. In the latter case,
20274 build_x_modify_expr sets it and it must not be reset
20275 here. */
20280 }
20285 /* Remember that there was a reference to this entity. */
20292 {
20297 tree ret;
20304 else
20305 {
20309 }
20311 /* If there was an initializer in the original tree, but it
20312 instantiated to an empty list, then we should pass a
20313 non-NULL empty vector to tell build_new that it was an
20314 empty initializer() rather than no initializer. This can
20315 only happen when the initializer is a pack expansion whose
20316 parameter packs are of length zero. */
20321 else
20322 {
20326 else
20327 {
20330 }
20331 }
20333 /* Avoid passing an enclosing decl to valid_array_size_p. */
20340 complain);
20348 }
20351 {
20357 complain));
20358 }
20361 {
20365 op0,
20369 }
20372 {
20373 tree function;
20377 tree ret;
20380 /* Internal function with no arguments. */
20384 /* When we parsed the expression, we determined whether or
20385 not Koenig lookup should be performed. */
20388 {
20391 }
20393 {
20398 }
20402 {
20404 in_decl);
20406 {
20413 }
20414 else
20417 }
20422 {
20423 /* Do nothing; calling tsubst_expr on an identifier
20424 would incorrectly perform unqualified lookup again.
20426 Note that we can also have an IDENTIFIER_NODE if the earlier
20427 unqualified lookup found a dependent local extern declaration
20428 (as per finish_call_expr); in that case koenig_p will be false
20429 and we do want to do the lookup again to find the substituted
20430 declaration. */
20435 }
20436 else
20437 {
20439 {
20445 }
20446 else
20451 /* Avoid error about taking the address of a constructor. */
20456 /* When KOENIG_P, we don't want to mark_used the callee before
20457 augmenting the overload set via ADL, so during this initial
20458 substitution we disable mark_used by setting tf_conv (68942). */
20464 }
20467 releasing_vec call_args;
20470 /* Stripped-down processing for a call in a thunk. Specifically, in
20471 the thunk template for a generic lambda. */
20473 {
20474 /* Now that we've expanded any packs, the number of call args
20475 might be different. */
20479 {
20486 }
20487 /* We aren't going to do normal overload resolution, so force the
20488 template-id to resolve. */
20491 {
20492 /* In a thunk, pass through args directly, without any
20493 conversions. */
20498 }
20500 {
20501 /* If there are no other args, just push 'this'. */
20504 else
20505 {
20506 /* Otherwise, shift the other args over to make room. */
20512 }
20513 }
20516 /* The thunk location is not interesting. */
20523 }
20525 /* We do not perform argument-dependent lookup if normal
20526 lookup finds a non-function, in accordance with the
20527 resolution of DR 218. */
20530 /* If lookup found a member function, the Koenig lookup is
20531 not appropriate, even if an unqualified-name was used
20532 to denote the function. */
20535 /* C++20 P0846: Lookup found nothing. */
20538 /* Only do this when substitution turns a dependent call
20539 into a non-dependent call. */
20551 {
20556 {
20557 /* For backwards compatibility and good diagnostics, try
20558 the unqualified lookup again if we aren't in SFINAE
20559 context. */
20565 {
20568 "and no declarations were found by "
20569 "argument-dependent lookup at the point "
20574 /* In a lambda fn, we have to be careful to not
20575 introduce new this captures. Legacy code can't
20576 be using lambdas anyway, so it's ok to be
20577 stricter. Be strict with C++20 template-id ADL too.
20578 And be strict if we're already failing anyway. */
20584 else
20588 {
20599 {
20602 "declarations in dependent base %qT are "
20608 else
20612 }
20613 else
20615 "%qD declared here, later in the "
20619 }
20622 }
20623 }
20625 {
20629 }
20630 }
20632 /* Remember that there was a reference to this entity. */
20641 /* Put back tf_decltype for the actual call. */
20646 {
20650 {
20652 "wrong number of arguments to "
20655 }
20656 else
20664 {
20666 "wrong number of arguments to "
20670 }
20674 complain);
20680 {
20682 complain);
20686 }
20691 {
20693 "wrong number of arguments to "
20696 }
20697 else
20698 {
20703 {
20706 }
20709 }
20713 /* Unsupported internal function with arguments. */
20715 }
20720 complain);
20722 {
20723 /* FUNCTION is a template-id referring to a concept definition. */
20728 /* Calls to standard and variable concepts should have been
20729 previously diagnosed. */
20732 /* Ensure the result is wrapped as a call expression. */
20734 }
20735 else
20738 koenig_p,
20739 complain);
20742 {
20748 {
20752 }
20754 /* This also suppresses -Wredundant-move. */
20756 }
20759 }
20762 {
20769 {
20771 {
20776 }
20777 else
20778 {
20783 }
20785 }
20786 else
20787 {
20790 }
20795 }
20798 {
20803 input_location));
20804 }
20810 {
20811 tree object;
20812 tree object_type;
20813 tree member;
20814 tree r;
20818 /* Remember that there was a reference to this entity. */
20829 else
20836 {
20839 }
20841 {
20843 complain);
20847 }
20851 {
20853 {
20858 {
20861 }
20863 {
20868 }
20869 }
20870 }
20873 {
20874 /* Lookup the template functions now that we know what the
20875 scope is. */
20882 {
20885 args);
20886 member = (adjust_result_of_qualified_name_lookup
20888 object_type));
20889 }
20890 else
20891 {
20893 input_location);
20895 }
20896 }
20900 {
20902 {
20906 else
20909 }
20911 }
20915 complain);
20919 }
20926 {
20933 tree r;
20942 /* We do not want to process the index of aggregate
20943 initializers as they are identifier nodes which will be
20944 looked up by digest_init. */
20948 {
20951 }
20956 {
20958 /* An identifier index is looked up in the type
20959 being initialized, not the current scope. */
20964 {
20965 /* Substitute into the pack expansion. */
20967 in_decl);
20971 ;
20973 /* Just move the argument into place. */
20975 else
20976 {
20977 /* Update the length of the final CONSTRUCTOR
20978 arguments vector, and note that we will need to
20979 copy.*/
20982 }
20983 }
20984 else
20986 }
20989 {
20994 {
20996 {
21001 }
21002 else
21004 }
21005 }
21013 {
21018 }
21022 }
21025 {
21028 {
21031 }
21032 else
21033 {
21036 }
21037 }
21044 tree r;
21049 {
21050 /* Local specialization will usually have been created when
21051 we instantiated the DECL_EXPR_DECL. */
21054 {
21055 /* We're in a generic lambda referencing a local extern
21056 from an outer block-scope of a non-template. */
21059 }
21060 }
21065 {
21067 {
21068 /* We get here for a use of 'this' in an NSDMI. */
21072 /* This can happen for a parameter name used later in a function
21073 declaration (such as in a late-specified return type). Just
21074 make a dummy decl, since it's only used for its type. */
21077 /* Give it the template pattern as its context; its true context
21078 hasn't been instantiated yet and this is good enough for
21079 mangling. */
21081 }
21083 {
21084 /* First try name lookup to find the instantiation. */
21087 {
21089 {
21090 /* During error-recovery we may find a non-variable,
21091 even an OVERLOAD: just bail out and avoid ICEs and
21092 duplicate diagnostics (c++/62207). */
21095 }
21097 {
21098 /* Make sure the one we found is the one we want. */
21102 }
21103 }
21107 else
21108 {
21109 /* This can happen for a variable used in a
21110 late-specified return type of a local lambda, or for a
21111 local static or constant. Building a new VAR_DECL
21112 should be OK in all those cases. */
21115 /* Avoid infinite recursion (79640). */
21118 {
21119 /* We can't call cp_finish_decl, so handle the
21120 initializer by hand. */
21135 }
21137 || processing_contract_condition
21144 }
21145 /* Remember this for subsequent uses. */
21148 }
21151 }
21152 else
21159 {
21160 /* ??? We're doing a subset of finish_id_expression here. */
21162 /* Replace an evaluated use of the thread_local variable with
21163 a call to its wrapper. */
21169 /* If the original type was a reference, we'll be wrapped in
21170 the appropriate INDIRECT_REF. */
21172 }
21176 {
21177 tree enum_type;
21178 tree v;
21185 /* Unfortunately, we cannot just call lookup_name here.
21186 Consider:
21188 template <int I> int f() {
21189 enum E { a = I };
21190 struct S { void g() { E e = a; } };
21191 };
21193 When we instantiate f<7>::S::g(), say, lookup_name is not
21194 clever enough to find f<7>::a. */
21195 enum_type
21205 /* We didn't find the name. That should never happen; if
21206 name-lookup found it during preliminary parsing, we
21207 should find it again here during instantiation. */
21210 }
21214 {
21215 tree ctx;
21220 {
21223 {
21227 }
21229 }
21230 }
21245 {
21246 /* Template template argument like the following example need
21247 special treatment:
21249 template <template <class> class TT> struct C {};
21250 template <class T> struct D {
21251 template <class U> struct E {};
21252 C<E> c; // #1
21253 };
21254 D<int> d; // #2
21256 We are processing the template argument `E' in #1 for
21257 the template instantiation #2. Originally, `E' is a
21258 TEMPLATE_DECL with `D<T>' as its DECL_CONTEXT. Now we
21259 have to substitute this with one having context `D<int>'. */
21264 }
21265 else
21266 /* Ordinary template template argument. */
21274 /* We shouldn't have built any of these during initial template
21275 generation. Instead, they should be built during instantiation
21276 in response to the saved STMT_IS_FULL_EXPR_P setting. */
21280 {
21290 }
21308 {
21309 /* Instantiate any typedefs in the type. */
21314 }
21317 {
21321 {
21324 }
21326 }
21329 /* These can sometimes show up in a partial instantiation, but never
21330 involve template parms. */
21346 /* ??? There's no point in copying it for now, but maybe some
21347 day it will contain more information, such as a pointer back
21348 to the containing function, inlined copy or so. */
21360 {
21364 }
21367 {
21368 tree object_ptr
21373 }
21380 {
21384 else
21390 }
21393 {
21402 /* If the resulting list of expression statement is empty,
21403 fold it further into void_node. */
21408 }
21411 {
21413 {
21414 /* We don't have a full set of template arguments yet; don't touch
21415 the lambda at all. */
21418 }
21422 }
21431 else
21432 /* Recreate the PAREN_EXPR from __builtin_assoc_barrier. */
21433 {
21437 }
21440 {
21445 complain));
21446 }
21449 {
21452 }
21455 /* No need to substitute further, a RANGE_EXPR will always be built
21456 with constant operands. */
21461 {
21465 /* We need to do this here as well as in tsubst_copy so we get the
21466 other tsubst_copy_and_build semantics for a PARM_DECL operand. */
21471 /* force_paren_expr can also create a VIEW_CONVERT_EXPR. */
21474 /* Otherwise, we're dealing with a wrapper to make a C++20 template
21475 parameter object const. */
21478 {
21479 /* The template argument is not const, presumably because
21480 it is still dependent, and so not the const template parm
21481 object. */
21485 {
21486 /* Don't add a wrapper to these. */
21489 }
21490 else
21491 /* Do add a wrapper otherwise (in particular, if op is
21492 another TEMPLATE_PARM_INDEX). */
21494 }
21496 }
21506 /* Handle Objective-C++ constructs, if appropriate. */
21510 /* We shouldn't get here, but keep going if !flag_checking. */
21514 }
21516 #undef RECUR
21517 #undef RETURN
21518 out:
21521 }
21523 /* Verify that the instantiated ARGS are valid. For type arguments,
21524 make sure that the type's linkage is ok. For non-type arguments,
21525 make sure they are constants if they are integral or enumerations.
21526 Emit an error under control of COMPLAIN, and return TRUE on error. */
21528 static bool
21530 {
21534 {
21544 }
21546 {
21547 /* [basic.link]: A name with no linkage (notably, the name
21548 of a class or enumeration declared in a local scope)
21549 shall not be used to declare an entity with linkage.
21550 This implies that names with no linkage cannot be used as
21551 template arguments
21553 DR 757 relaxes this restriction for C++0x. */
21558 {
21559 /* DR 488 makes use of a type with no linkage cause
21560 type deduction to fail. */
21562 {
21565 else
21568 }
21570 }
21571 /* In order to avoid all sorts of complications, we do not
21572 allow variably-modified types as template arguments. */
21574 {
21578 }
21579 }
21580 /* Class template and alias template arguments should be OK. */
21582 ;
21583 /* A non-type argument of integral or enumerated type must be a
21584 constant. */
21589 {
21593 }
21595 }
21597 static bool
21599 {
21604 {
21607 }
21611 }
21613 /* Call mark_used on each entity within the non-type template arguments in
21614 ARGS for an instantiation of TMPL, to ensure that each such entity is
21615 considered odr-used (and therefore marked for instantiation) regardless of
21616 whether the specialization was first formed in a template context (which
21617 inhibits mark_used).
21619 This function assumes push_to_top_level has been called beforehand. */
21621 static void
21623 {
21624 /* It suffices to do this only when instantiating a primary template. */
21628 /* We already marked outer arguments when specializing the context. */
21632 {
21633 /* A (pointer/reference to) function or variable NTTP argument. */
21636 {
21642 {
21643 /* Pass tf_none to avoid duplicate diagnostics: if this call
21644 fails then an earlier call to mark_used for this argument
21645 must have also failed and emitted a diagnostic. */
21648 }
21649 }
21650 /* A class NTTP argument. */
21653 {
21656 {
21659 }
21661 };
21664 }
21665 }
21666 }
21668 /* We're out of SFINAE context now, so generate diagnostics for the access
21669 errors we saw earlier when instantiating D from TMPL and ARGS. */
21671 static void
21673 {
21685 }
21687 /* Instantiate the indicated variable, function, or alias template TMPL with
21688 the template arguments in TARG_PTR. */
21690 tree
21692 {
21696 tree fndecl;
21697 tree gen_tmpl;
21703 /* The other flags are not relevant anymore here, especially tf_partial
21704 shouldn't be set. For instance, we may be called while doing a partial
21705 substitution of a template variable, but the type of the variable
21706 template may be auto, in which case we will call do_auto_deduction
21707 in mark_used (which clears tf_partial) and the auto must be properly
21708 reduced at that time for the deduction to work. */
21716 /* If this function is a clone, handle it specially. */
21718 {
21719 tree spec;
21720 tree clone;
21722 /* Use DECL_ABSTRACT_ORIGIN because only FUNCTION_DECLs have
21723 DECL_CLONED_FUNCTION. */
21729 /* Look for the clone. */
21733 /* We should always have found the clone by now. */
21736 }
21741 /* Check to see if we already have this specialization. */
21745 /* targ_ptr only has the innermost template args, so add the outer ones
21746 from tmpl, which could be either a partial instantiation or gen_tmpl (in
21747 the case of a non-dependent call within a template definition). */
21748 targ_ptr = (add_outermost_template_args
21750 targ_ptr));
21756 || ((fndecl
21762 {
21764 {
21768 }
21770 }
21773 complain))
21776 /* We are building a FUNCTION_DECL, during which the access of its
21777 parameters and return types have to be checked. However this
21778 FUNCTION_DECL which is the desired context for access checking
21779 is not built yet. We solve this chicken-and-egg problem by
21780 deferring all checks until we have the FUNCTION_DECL. */
21783 /* Instantiation of the function happens in the context of the function
21784 template, not the context of the overload resolution we're doing. */
21786 /* If there are dependent arguments, e.g. because we're doing partial
21787 ordering, make sure processing_template_decl stays set. */
21791 {
21792 tree ctx;
21794 /* If the context of the partially instantiated template is
21795 already non-dependent, then we might as well use it. */
21797 else
21801 }
21808 {
21809 /* We need to determine if we're using a partial or explicit
21810 specialization now, because the type of the variable could be
21811 different. */
21817 {
21823 }
21824 }
21826 /* Substitute template parameters to obtain the specialization. */
21834 {
21837 }
21839 /* The DECL_TI_TEMPLATE should always be the immediate parent
21840 template, not the most general template. */
21844 /* Now that we we've formed this variable template specialization,
21845 remember the result of most_specialized_partial_spec for it. */
21854 /* Now we know the specialization, compute access previously
21855 deferred. Do no access control for inheriting constructors,
21856 as we already checked access for the inherited constructor. */
21859 {
21864 }
21867 /* If we've just instantiated the main entry point for a function,
21868 instantiate all the alternate entry points as well. We do this
21869 by cloning the instantiation of the main entry point, not by
21870 instantiating the template clones. */
21876 {
21878 {
21879 /* Remember to reinstantiate when we're out of SFINAE so the user
21880 can see the errors. */
21882 }
21884 }
21887 }
21889 /* Instantiate the alias template TMPL with ARGS. Also push a template
21890 instantiation level, which instantiate_template doesn't do because
21891 functions and variables have sufficient context established by the
21892 callers. */
21894 static tree
21896 {
21905 /* FIXME check for satisfaction in check_instantiated_args. */
21907 {
21909 {
21910 auto_diagnostic_group d;
21913 }
21915 }
21923 {
21924 /* An alias template specialization can be dependent
21925 even if its underlying type is not. */
21928 /* Sometimes a dependent alias spec is equivalent to its expansion,
21929 sometimes not. So always use structural_comptypes. */
21931 }
21934 }
21936 /* PARM is a template parameter pack for FN. Returns true iff
21937 PARM is used in a deducible way in the argument list of FN. */
21939 static bool
21941 {
21944 {
21946 tree packs;
21952 {
21953 /* The template parameter pack is used in a function parameter
21954 pack. If this is the end of the parameter list, the
21955 template parameter pack is deducible. */
21958 else
21959 /* Otherwise, not. Well, it could be deduced from
21960 a non-pack parameter, but doing so would end up with
21961 a deduction mismatch, so don't bother. */
21963 }
21964 }
21965 /* The template parameter pack isn't used in any function parameter
21966 packs, but it might be used deeper, e.g. tuple<Args...>. */
21968 }
21970 /* Subroutine of fn_type_unification: check non-dependent parms for
21971 convertibility. */
21973 static int
21978 {
21979 /* Non-constructor methods need to leave a conversion for 'this', which
21980 isn't included in nargs here. */
21986 {
21992 /* For a function parameter pack that occurs at the end of the
21993 parameter-declaration-list, the type A of each remaining
21994 argument of the call is compared with the type P of the
21995 declarator-id of the function parameter pack. */
22001 /* For a function parameter pack that does not occur at the
22002 end of the parameter-declaration-list, the type of the
22003 parameter pack is a non-deduced context. */
22007 {
22015 }
22018 }
22021 }
22023 /* The FN is a TEMPLATE_DECL for a function. ARGS is an array with
22024 NARGS elements of the arguments that are being used when calling
22025 it. TARGS is a vector into which the deduced template arguments
22026 are placed.
22028 Returns either a FUNCTION_DECL for the matching specialization of FN or
22029 NULL_TREE if no suitable specialization can be found. If EXPLAIN_P is
22030 true, diagnostics will be printed to explain why it failed.
22032 If FN is a conversion operator, or we are trying to produce a specific
22033 specialization, RETURN_TYPE is the return type desired.
22035 The EXPLICIT_TARGS are explicit template arguments provided via a
22036 template-id.
22038 The parameter STRICT is one of:
22040 DEDUCE_CALL:
22041 We are deducing arguments for a function call, as in
22042 [temp.deduct.call]. If RETURN_TYPE is non-null, we are
22043 deducing arguments for a call to the result of a conversion
22044 function template, as in [over.call.object].
22046 DEDUCE_CONV:
22047 We are deducing arguments for a conversion function, as in
22048 [temp.deduct.conv].
22050 DEDUCE_EXACT:
22051 We are deducing arguments when doing an explicit instantiation
22052 as in [temp.explicit], when determining an explicit specialization
22053 as in [temp.expl.spec], or when taking the address of a function
22054 template, as in [temp.deduct.funcaddr]. */
22056 tree
22058 tree explicit_targs,
22059 tree targs,
22062 tree return_type,
22063 unification_kind_t strict,
22068 {
22069 tree parms;
22070 tree fntype;
22075 /* type_unification_real will pass back any access checks from default
22076 template argument substitution. */
22078 /* We don't have all the template args yet. */
22091 full_targs = (add_outermost_template_args
22093 targs));
22098 /* In C++0x, it's possible to have a function template whose type depends
22099 on itself recursively. This is most obvious with decltype, but can also
22100 occur with enumeration scope (c++/48969). So we need to catch infinite
22101 recursion and reject the substitution at deduction time; this function
22102 will return error_mark_node for any repeated substitution.
22104 This also catches excessive recursion such as when f<N> depends on
22105 f<N-1> across all integers, and returns error_mark_node for all the
22106 substitutions back up to the initial one.
22108 This is, of course, not reentrant. */
22117 {
22118 /* [temp.deduct]
22120 The specified template arguments must match the template
22121 parameters in kind (i.e., type, nontype, template), and there
22122 must not be more arguments than there are parameters;
22123 otherwise type deduction fails.
22125 Nontype arguments must match the types of the corresponding
22126 nontype template parameters, or must be convertible to the
22127 types of the corresponding nontype parameters as specified in
22128 _temp.arg.nontype_, otherwise type deduction fails.
22130 All references in the function type of the function template
22131 to the corresponding template parameters are replaced by the
22132 specified template argument values. If a substitution in a
22133 template parameter or in the function type of the function
22134 template results in an invalid type, type deduction fails. */
22145 explicit_targs);
22147 /* Adjust any explicit template arguments before entering the
22148 substitution context. */
22149 explicit_targs
22156 /* Substitute the explicit args into the function type. This is
22157 necessary so that, for instance, explicitly declared function
22158 arguments can match null pointed constants. If we were given
22159 an incomplete set of explicit args, we must not do semantic
22160 processing during substitution as we could create partial
22161 instantiations. */
22163 {
22168 /* Dig out the actual parm. */
22171 {
22174 }
22176 {
22179 }
22182 /* No explicit argument for this template parameter. */
22185 {
22186 /* Mark the argument pack as "incomplete". We could
22187 still deduce more arguments during unification.
22188 We remove this mark in type_unification_real. */
22193 /* We have some incomplete argument packs. */
22195 }
22196 }
22199 {
22201 {
22204 }
22207 /* Ignore any access checks; we'll see them again in
22208 instantiate_template and they might have the wrong
22209 access path at this point. */
22220 }
22222 /* Place the explicitly specified arguments in TARGS. */
22228 SET_NON_DEFAULT_TEMPLATE_ARGS_COUNT
22230 }
22233 {
22239 }
22244 /* Never do unification on the 'this' parameter. */
22248 {
22249 /* We're deducing for a call to the result of a template conversion
22250 function. The parms we really want are in return_type. */
22254 }
22256 {
22258 }
22260 /* We allow incomplete unification without an error message here
22261 because the standard doesn't seem to explicitly prohibit it. Our
22262 callers must be ready to deal with unification failures in any
22263 event. */
22265 /* If we aren't explaining yet, push tinst context so we can see where
22266 any errors (e.g. from class instantiations triggered by instantiation
22267 of default template arguments) come from. If we are explaining, this
22268 context is redundant. */
22270 {
22273 }
22283 /* Now that we have bindings for all of the template arguments,
22284 ensure that the arguments deduced for the template template
22285 parameters have compatible template parameter lists. We cannot
22286 check this property before we have deduced all template
22287 arguments, because the template parameter types of a template
22288 template parameter might depend on prior template parameters
22289 deduced after the template template parameter. The following
22290 ill-formed example illustrates this issue:
22292 template<typename T, template<T> class C> void f(C<5>, T);
22294 template<int N> struct X {};
22296 void g() {
22297 f(X<5>(), 5l); // error: template argument deduction fails
22298 }
22300 The template parameter list of 'C' depends on the template type
22301 parameter 'T', but 'C' is deduced to 'X' before 'T' is deduced to
22302 'long'. Thus, we can't check that 'C' cannot bind to 'X' at the
22303 time that we deduce 'C'. */
22306 {
22309 }
22311 deduced:
22313 /* As a refinement of CWG2369, check first and foremost non-dependent
22314 conversions that we know are not going to induce template instantiation
22315 (PR99599). */
22317 && incomplete
22323 /* CWG2369: Check satisfaction before non-deducible conversions. */
22325 {
22329 }
22331 /* DR 1391: All parameters have args, now check non-dependent parms for
22332 convertibility. We don't do this if all args were explicitly specified,
22333 as the standard says that we substitute explicit args immediately. */
22340 /* All is well so far. Now, check:
22342 [temp.deduct]
22344 When all template arguments have been deduced, all uses of
22345 template parameters in nondeduced contexts are replaced with
22346 the corresponding deduced argument values. If the
22347 substitution results in an invalid type, as described above,
22348 type deduction fails. */
22350 {
22353 }
22355 /* Also collect access checks from the instantiation. */
22368 /* Now perform any access checks encountered during substitution. */
22375 /* If we're looking for an exact match, check that what we got
22376 is indeed an exact match. It might not be if some template
22377 parameters are used in non-deduced contexts. But don't check
22378 for an exact match if we have dependent template arguments;
22379 in that case we're doing partial ordering, and we already know
22380 that we have two candidates that will provide the actual type. */
22382 {
22386 tree sarg
22392 {
22396 }
22398 /* add_candidates uses DEDUCE_EXACT for x.operator foo(), but args
22399 doesn't contain the trailing void, and conv fns are always (). */
22401 {
22405 }
22406 }
22408 /* After doing deduction with the inherited constructor, actually return an
22409 instantiation of the inheriting constructor. */
22415 fail:
22418 {
22420 /* Reset once we're all the way out. */
22422 }
22425 }
22427 /* Returns true iff PARM is a forwarding reference in the context of
22428 template argument deduction for TMPL. */
22430 static bool
22432 {
22433 /* [temp.deduct.call], "A forwarding reference is an rvalue reference to a
22434 cv-unqualified template parameter ..." */
22439 {
22441 /* [temp.deduct.call], "... that does not represent a template parameter
22442 of a class template (during class template argument deduction)." */
22446 {
22447 /* Since the template parameters of a synthesized guide consist of
22448 the template parameters of the class template followed by those of
22449 the constructor (if any), we can tell if PARM represents a template
22450 parameter of the class template by comparing its index with the
22451 arity of the class template. */
22456 }
22458 }
22460 }
22462 /* Adjust types before performing type deduction, as described in
22463 [temp.deduct.call] and [temp.deduct.conv]. The rules in these two
22464 sections are symmetric. PARM is the type of a function parameter
22465 or the return type of the conversion function. ARG is the type of
22466 the argument passed to the call, or the type of the value
22467 initialized with the result of the conversion function.
22468 ARG_EXPR is the original argument expression, which may be null. */
22470 static int
22472 unification_kind_t strict,
22475 tree arg_expr)
22476 {
22480 {
22485 /* [temp.deduct.conv] First remove a reference type on parm.
22486 DRs 322 & 976 affected this. */
22490 /* Swap PARM and ARG throughout the remainder of this
22491 function; the handling is precisely symmetric since PARM
22492 will initialize ARG rather than vice versa. */
22498 /* Core issue #873: Do the DR606 thing (see below) for these cases,
22499 too, but here handle it by stripping the reference from PARM
22500 rather than by adding it to ARG. */
22505 /* Nothing else to do in this case. */
22510 }
22513 {
22514 /* [temp.deduct.call]
22516 If P is not a reference type:
22518 --If A is an array type, the pointer type produced by the
22519 array-to-pointer standard conversion (_conv.array_) is
22520 used in place of A for type deduction; otherwise,
22522 --If A is a function type, the pointer type produced by
22523 the function-to-pointer standard conversion
22524 (_conv.func_) is used in place of A for type deduction;
22525 otherwise,
22527 --If A is a cv-qualified type, the top level
22528 cv-qualifiers of A's type are ignored for type
22529 deduction. */
22534 else
22536 }
22538 /* [temp.deduct.call], "If P is a forwarding reference and the argument is
22539 an lvalue, the type 'lvalue reference to A' is used in place of A for
22540 type deduction." */
22543 /* try_one_overload doesn't provide an arg_expr, but
22544 functions are always lvalues. */
22548 /* [temp.deduct.call]
22550 If P is a cv-qualified type, the top level cv-qualifiers
22551 of P's type are ignored for type deduction. If P is a
22552 reference type, the type referred to by P is used for
22553 type deduction. */
22556 {
22559 }
22562 }
22564 /* Return true if computing a conversion from FROM to TO might induce template
22565 instantiation. Conversely, if this predicate returns false then computing
22566 the conversion definitely won't induce template instantiation. */
22568 static bool
22570 {
22577 {
22581 }
22583 /* If one of the types is a not-yet-instantiated class template
22584 specialization, then computing the conversion might instantiate
22585 it in order to inspect bases, conversion functions and/or
22586 converting constructors. */
22595 /* Converting from one pointer type to another, or between
22596 reference-related types, always yields a standard conversion. */
22600 /* Converting to a non-aggregate class type will consider its
22601 user-declared constructors, which might induce instantiation. */
22606 /* Similarly, converting from a class type will consider its conversion
22607 functions. */
22612 /* Otherwise, computing this conversion definitely won't induce
22613 template instantiation. */
22615 }
22617 /* Subroutine of fn_type_unification. PARM is a function parameter of a
22618 template which doesn't contain any deducible template parameters; check if
22619 ARG is a suitable match for it. STRICT, FLAGS and EXPLAIN_P are as in
22620 unify_one_argument. */
22622 static int
22626 {
22627 tree type;
22631 else
22639 {
22642 }
22644 {
22646 {
22647 /* This conversion was already computed earlier (when
22648 computing only non-instantiating conversions). */
22651 }
22660 /* Avoid recalculating this in add_function_candidate. */
22661 ok = (*conv_p
22663 else
22667 }
22671 else
22673 }
22677 /* Returns true iff the expression EXPR is one from which a template
22678 argument can be deduced. In other words, if it's an undecorated
22679 use of a template non-type parameter. */
22681 static bool
22683 {
22684 /* Strip implicit conversions and implicit INDIRECT_REFs. */
22690 }
22692 /* Returns true iff the array domain DOMAIN uses a template parameter in a
22693 deducible way; that is, if it has a max value of <PARM> - 1. */
22695 static bool
22697 {
22706 }
22708 /* Returns true iff the template arguments ARGS use a template parameter
22709 in a deducible way. */
22711 static bool
22713 {
22715 {
22719 else
22720 {
22727 else
22729 }
22732 }
22734 }
22736 /* Returns true iff TYPE contains any deducible references to template
22737 parameters, as per 14.8.2.5. */
22739 static bool
22741 {
22745 /* T
22746 cv-list T
22747 TT<T>
22748 TT<i>
22749 TT<> */
22754 /* T*
22755 T&
22756 T&& */
22760 /* T[integer-constant ]
22761 type [i] */
22766 /* T type ::*
22767 type T::*
22768 T T::*
22769 T (type ::*)()
22770 type (T::*)()
22771 type (type ::*)(T)
22772 type (T::*)(T)
22773 T (type ::*)(T)
22774 T (T::*)()
22775 T (T::*)(T) */
22778 || (uses_deducible_template_parms
22781 /* template-name <T> (where template-name refers to a class template)
22782 template-name <i> (where template-name refers to a class template) */
22789 /* type (T)
22790 T()
22791 T(T) */
22793 {
22807 }
22810 }
22812 /* Subroutine of type_unification_real and unify_pack_expansion to
22813 handle unification of a single P/A pair. Parameters are as
22814 for those functions. */
22816 static int
22820 {
22827 /* We can't deduce anything from this, but we might get all the
22828 template args from other function args. */
22831 /* Implicit conversions (Clause 4) will be performed on a function
22832 argument to convert it to the type of the corresponding function
22833 parameter if the parameter type contains no template-parameters that
22834 participate in template argument deduction. */
22837 /* For function parameters with no deducible template parameters,
22838 just return. We'll check non-dependent conversions later. */
22842 {
22844 arg_strict = (UNIFY_ALLOW_OUTER_LEVEL
22845 | UNIFY_ALLOW_MORE_CV_QUAL
22859 }
22861 /* We only do these transformations if this is the top-level
22862 parameter_type_list in a call or declaration matching; in other
22863 situations (nested function declarators, template argument lists) we
22864 won't be comparing a type to an expression, and we don't do any type
22865 adjustments. */
22867 {
22869 {
22872 {
22873 /* [temp.deduct.type] A template-argument can be
22874 deduced from a pointer to function or pointer
22875 to member function argument if the set of
22876 overloaded functions does not contain function
22877 templates and at most one of a set of
22878 overloaded functions provides a unique
22879 match. */
22883 /* If a unique match was not found, this is a
22884 non-deduced context, so we still succeed. */
22886 }
22892 }
22896 }
22897 else
22902 /* For deduction from an init-list we need the actual list. */
22906 }
22908 /* for_each_template_parm callback that always returns 0. */
22910 static int
22912 {
22914 }
22916 /* for_each_template_parm any_fn callback to handle deduction of a template
22917 type argument from the type of an array bound. */
22919 static int
22921 {
22929 {
22935 }
22937 /* Keep walking. */
22939 }
22941 /* Try to deduce any not-yet-deduced template type arguments from the type of
22942 an array bound. This is handled separately from unify because 14.8.2.5 says
22943 "The type of a type parameter is only deduced from an array bound if it is
22944 not otherwise deduced." */
22946 static void
22948 {
22953 }
22955 /* Most parms like fn_type_unification.
22957 If SUBR is 1, we're being called recursively (to unify the
22958 arguments of a function or method parameter of a function
22959 template).
22961 CHECKS is a pointer to a vector of access checks encountered while
22962 substituting default template arguments. */
22964 static int
22966 tree full_targs,
22967 tree xparms,
22971 unification_kind_t strict,
22974 {
22979 tree parms;
22990 /* Reset the number of non-defaulted template arguments contained
22991 in TARGS. */
22994 again:
22999 /* Only fn_type_unification cares about terminal void. */
23006 {
23011 /* For a function parameter pack that occurs at the end of the
23012 parameter-declaration-list, the type A of each remaining
23013 argument of the call is compared with the type P of the
23014 declarator-id of the function parameter pack. */
23020 /* For a function parameter pack that does not occur at the
23021 end of the parameter-declaration-list, the type of the
23022 parameter pack is a non-deduced context. */
23029 explain_p))
23031 }
23036 {
23037 /* Unify the remaining arguments with the pack expansion type. */
23038 tree argvec;
23041 /* Allocate a TREE_VEC and copy in all of the arguments */
23046 /* Copy the parameter into parmvec. */
23052 /* Advance to the end of the list of parameters. */
23054 }
23056 /* Fail if we've reached the end of the parm list, and more args
23057 are present, and the parm list isn't variadic. */
23060 /* Fail if parms are left and they don't have default values and
23061 they aren't all deduced as empty packs (c++/57397). This is
23062 consistent with sufficient_parms_p. */
23065 {
23069 do
23070 {
23073 count++;
23075 }
23079 type_pack_p);
23080 }
23083 {
23084 tsubst_flags_t complain = (explain_p
23085 ? tf_warning_or_error
23090 {
23094 /* Clear the "incomplete" flags on all argument packs now so that
23095 substituting them into later default arguments works. */
23097 {
23100 }
23108 {
23113 }
23115 /* If this is an undeduced nontype parameter that depends on
23116 a type parameter, try another pass; its type may have been
23117 deduced from a later argument than the one from which
23118 this parameter can be deduced. */
23123 {
23126 }
23128 /* Core issue #226 (C++0x) [temp.deduct]:
23130 If a template argument has not been deduced, its
23131 default template argument, if any, is used.
23133 When we are in C++98 mode, TREE_PURPOSE will either
23134 be NULL_TREE or ERROR_MARK_NODE, so we do not need
23135 to explicitly check cxx_dialect here. */
23137 /* OK, there is a default argument. Wait until after the
23138 conversion check to do substitution. */
23141 /* If the type parameter is a parameter pack, then it will
23142 be deduced to an empty parameter pack. */
23144 {
23145 tree arg;
23148 {
23151 }
23152 else
23159 }
23162 }
23164 /* During partial ordering, we deduce dependent template args. */
23167 /* Now substitute into the default template arguments. */
23169 {
23174 {
23178 }
23193 {
23194 /* The type of this non-type parameter depends on undeduced
23195 parameters. Don't try to use its default argument yet,
23196 since we might deduce an argument for it on the next pass,
23197 but do check whether the arguments we already have cause
23198 substitution failure, so that that happens before we try
23199 later default arguments (78489). */
23202 NULL_TREE);
23206 else
23208 }
23209 else
23210 {
23211 /* Even if the call is happening in template context, getting
23212 here means it's non-dependent, and a default argument is
23213 considered a separate definition under [temp.decls], so we can
23214 do this substitution without processing_template_decl. This
23215 is important if the default argument contains something that
23216 might be instantiation-dependent like access (87480). */
23220 {
23221 /* First instatiate in template context, in case we still
23222 depend on undeduced template parameters. */
23225 NULL_TREE);
23229 /* We replaced all the tparms, substitute again out of
23230 template context. */
23232 }
23235 NULL_TREE);
23244 }
23253 {
23255 /* The position of the first default template argument,
23256 is also the number of non-defaulted arguments in TARGS.
23257 Record that. */
23260 }
23261 }
23265 }
23271 }
23273 /* Subroutine of type_unification_real. Args are like the variables
23274 at the call site. ARG is an overloaded function (or template-id);
23275 we try deducing template args from each of the overloads, and if
23276 only one succeeds, we go with that. Modifies TARGS and returns
23277 true on success. */
23279 static bool
23281 tree targs,
23282 tree parm,
23283 tree arg,
23284 unification_kind_t strict,
23287 {
23294 {
23297 }
23298 else
23302 /* Handle `&x' where `x' is some static or non-static member
23303 function name. */
23309 /* Strip baselink information. */
23314 {
23315 /* If we got some explicit template args, we need to plug them into
23316 the affected templates before we try to unify, in case the
23317 explicit args will completely resolve the templates in question. */
23324 {
23335 {
23340 {
23341 /* Instantiate the function to deduce its return type. */
23345 }
23354 {
23357 }
23358 }
23361 }
23362 /* If no templates (or more than one) are fully resolved by the
23363 explicit arguments, this template-id is a non-deduced context; it
23364 could still be OK if we deduce all template arguments for the
23365 enclosing call through other arguments. */
23368 }
23370 /* If ARG is, for example, "(0, &f)" then its type will be unknown
23371 -- but the deduction does not succeed because the expression is
23372 not just the function on its own. */
23374 else
23376 {
23381 {
23384 }
23385 }
23387 /* [temp.deduct.type] A template-argument can be deduced from a pointer
23388 to function or pointer to member function argument if the set of
23389 overloaded functions does not contain function templates and at most
23390 one of a set of overloaded functions provides a unique match.
23392 So if we found multiple possibilities, we return success but don't
23393 deduce anything. */
23396 {
23400 {
23405 /* Don't forget explicit template arguments in a pack. */
23409 }
23410 }
23415 }
23417 /* Core DR 115: In contexts where deduction is done and fails, or in
23418 contexts where deduction is not done, if a template argument list is
23419 specified and it, along with any default template arguments, identifies
23420 a single function template specialization, then the template-id is an
23421 lvalue for the function template specialization. */
23423 tree
23425 {
23438 {
23441 }
23443 {
23446 }
23448 {
23451 }
23454 {
23458 /* If we got some explicit template args, we need to plug them into
23459 the affected templates before we try to unify, in case the
23460 explicit args will completely resolve the templates in question. */
23468 {
23479 {
23482 {
23485 }
23488 {
23491 }
23492 }
23493 }
23495 {
23503 {
23504 tree base
23507 }
23511 }
23513 /* There were no good options and at least one bad one, so let the
23514 user know what the problem is. */
23516 }
23518 }
23520 /* As above, but error out if the expression remains overloaded. */
23522 tree
23524 {
23527 {
23531 }
23533 }
23535 /* Subroutine of resolve_overloaded_unification; does deduction for a single
23536 overload. Fills TARGS with any deduced arguments, or error_mark_node if
23537 different overloads deduce different arguments for a given parm.
23538 ADDR_P is true if the expression for which deduction is being
23539 performed was of the form "& fn" rather than simply "fn".
23541 Returns 1 on success. */
23543 static int
23545 tree orig_targs,
23546 tree targs,
23547 tree parm,
23548 tree arg,
23549 unification_kind_t strict,
23553 {
23555 tree tempargs;
23561 /* [temp.deduct.type] A template-argument can be deduced from a pointer
23562 to function or pointer to member function argument if the set of
23563 overloaded functions does not contain function templates and at most
23564 one of a set of overloaded functions provides a unique match.
23566 So if this is a template, just return success. */
23579 /* We don't copy orig_targs for this because if we have already deduced
23580 some template args from previous args, unify would complain when we
23581 try to deduce a template parameter for the same argument, even though
23582 there isn't really a conflict. */
23589 /* First make sure we didn't deduce anything that conflicts with
23590 explicitly specified args. */
23592 {
23599 /* Since we're unifying against ourselves, we will fill in
23600 template args used in the function parm list with our own
23601 template parms. Discard them. */
23604 {
23605 /* Check that the argument at each index of the deduced argument pack
23606 is equivalent to the corresponding explicitly specified argument.
23607 We may have deduced more arguments than were explicitly specified,
23608 and that's OK. */
23610 /* We used to assert ARGUMENT_PACK_INCOMPLETE_P (oldelt) here, but
23611 that's wrong if we deduce the same argument pack from multiple
23612 function arguments: it's only incomplete the first time. */
23625 }
23628 }
23631 {
23636 }
23639 }
23641 /* PARM is a template class (perhaps with unbound template
23642 parameters). ARG is a fully instantiated type. If ARG can be
23643 bound to PARM, return ARG, otherwise return NULL_TREE. TPARMS and
23644 TARGS are as for unify. */
23646 static tree
23649 {
23657 /* We need to make a new template argument vector for the call to
23658 unify. If we used TARGS, we'd clutter it up with the result of
23659 the attempted unification, even if this class didn't work out.
23660 We also don't want to commit ourselves to all the unifications
23661 we've already done, since unification is supposed to be done on
23662 an argument-by-argument basis. In other words, consider the
23663 following pathological case:
23665 template <int I, int J, int K>
23666 struct S {};
23668 template <int I, int J>
23669 struct S<I, J, 2> : public S<I, I, I>, S<J, J, J> {};
23671 template <int I, int J, int K>
23672 void f(S<I, J, K>, S<I, I, I>);
23674 void g() {
23675 S<0, 0, 0> s0;
23676 S<0, 1, 2> s2;
23678 f(s0, s2);
23679 }
23681 Now, by the time we consider the unification involving `s2', we
23682 already know that we must have `f<0, 0, 0>'. But, even though
23683 `S<0, 1, 2>' is derived from `S<0, 0, 0>', the code is invalid
23684 because there are two ways to unify base classes of S<0, 1, 2>
23685 with S<I, I, I>. If we kept the already deduced knowledge, we
23686 would reject the possibility I=1. */
23694 else
23701 }
23703 /* Given a template type PARM and a class type ARG, find the unique
23704 base type in ARG that is an instance of PARM. We do not examine
23705 ARG itself; only its base-classes. If there is not exactly one
23706 appropriate base class, return NULL_TREE. PARM may be the type of
23707 a partial specialization, as well as a plain template type. Used
23708 by unify. */
23710 static enum template_base_result
23713 {
23715 tree binfo;
23721 {
23722 /* The type could not be completed. */
23725 }
23727 /* Walk in inheritance graph order. The search order is not
23728 important, and this avoids multiple walks of virtual bases. */
23730 {
23735 {
23736 /* If there is more than one satisfactory baseclass, then:
23738 [temp.deduct.call]
23740 If they yield more than one possible deduced A, the type
23741 deduction fails.
23743 applies. */
23745 {
23746 /* [temp.deduct.call]/4.3: If there is a class C that is a
23747 (direct or indirect) base class of D and derived (directly or
23748 indirectly) from a class B and that would be a valid deduced
23749 A, the deduced A cannot be B or pointer to B, respectively. */
23751 /* Ignore r. */
23755 else
23756 {
23759 }
23760 }
23763 }
23764 }
23768 }
23770 /* Returns the level of DECL, which declares a template parameter. */
23772 static int
23774 {
23776 {
23786 }
23788 }
23790 /* Decide whether ARG can be unified with PARM, considering only the
23791 cv-qualifiers of each type, given STRICT as documented for unify.
23792 Returns nonzero iff the unification is OK on that basis. */
23794 static int
23796 {
23802 {
23803 /* Although a CVR qualifier is ignored when being applied to a
23804 substituted template parameter ([8.3.2]/1 for example), that
23805 does not allow us to unify "const T" with "int&" because both
23806 types are not of the form "cv-list T" [14.8.2.5 temp.deduct.type].
23807 It is ok when we're allowing additional CV qualifiers
23808 at the outer level [14.8.2.1]/3,1st bullet. */
23817 }
23828 }
23830 /* Determines the LEVEL and INDEX for the template parameter PARM. */
23831 void
23833 {
23837 {
23840 }
23841 else
23842 {
23845 }
23846 }
23848 #define RECUR_AND_CHECK_FAILURE(TP, TA, P, A, S, EP) \
23849 do { \
23850 if (unify (TP, TA, P, A, S, EP)) \
23851 return 1; \
23852 } while (0)
23854 /* Unifies the remaining arguments in PACKED_ARGS with the pack
23855 expansion at the end of PACKED_PARMS. Returns 0 if the type
23856 deduction succeeds, 1 otherwise. STRICT is the same as in
23857 fn_type_unification. CALL_ARGS_P is true iff PACKED_ARGS is actually a
23858 function call argument list. We'll need to adjust the arguments to make them
23859 types. SUBR tells us if this is from a recursive call to
23860 type_unification_real, or for comparing two template argument
23861 lists. */
23863 static int
23867 {
23868 tree parm
23874 /* Add in any args remembered from an earlier partial instantiation. */
23882 /* Determine the parameter packs we will be deducing from the
23883 pattern, and record their current deductions. */
23886 {
23890 /* Only template parameter packs can be deduced, not e.g. function
23891 parameter packs or __bases or __integer_pack. */
23895 /* Determine the index and level of this parameter pack. */
23900 /* Keep track of the parameter packs and their corresponding
23901 argument packs. */
23904 }
23906 /* Loop through all of the arguments that have not yet been
23907 unified and unify each with the pattern. */
23909 {
23910 tree parm;
23914 /* For each parameter pack, set its TMPL_ARG to either NULL_TREE
23915 or the element of its argument pack at the current index if
23916 this argument was explicitly specified. */
23918 {
23927 {
23930 }
23932 }
23934 /* If we had explicit template arguments, substitute them into the
23935 pattern before deduction. */
23937 {
23938 /* Some arguments might still be unspecified or dependent. */
23946 NULL_TREE);
23951 }
23952 else
23955 /* Unify the pattern with the current argument. */
23957 explain_p))
23960 /* For each parameter pack, collect the deduced value. */
23962 {
23968 }
23969 }
23971 /* Verify that the results of unification with the parameter packs
23972 produce results consistent with what we've seen before, and make
23973 the deduced argument packs available. */
23975 {
23982 /* By default keep the original deduced argument pack.
23983 If necessary, more specific code is going to update the
23984 resulting deduced argument later down in this function. */
23988 /* If NEW_ARGS contains any NULL_TREE entries, we didn't
23989 actually deduce anything. */
23997 {
23998 /* If we had fewer function args than explicit template args,
23999 just use the explicits. */
24004 }
24007 {
24008 tree result;
24009 /* Build the deduced *_ARGUMENT_PACK. */
24011 {
24014 }
24015 else
24020 /* Note the deduced argument packs for this parameter
24021 pack. */
24023 }
24027 {
24028 /* We only had the explicitly-provided arguments before, but
24029 now we have a complete set of arguments. */
24035 }
24036 else
24037 {
24041 /* During template argument deduction for the aggregate deduction
24042 candidate, the number of elements in a trailing parameter pack
24043 is only deduced from the number of remaining function
24044 arguments if it is not otherwise deduced. */
24047 /* FIXME This isn't set properly for partial instantiations. */
24053 /* Inconsistent unification of this parameter pack. */
24055 bad_old_arg,
24056 bad_new_arg);
24057 }
24058 }
24061 }
24063 /* Handle unification of the domain of an array. PARM_DOM and ARG_DOM are
24064 INTEGER_TYPEs representing the TYPE_DOMAIN of ARRAY_TYPEs. The other
24065 parameters and return value are as for unify. */
24067 static int
24071 {
24072 tree parm_max;
24073 tree arg_max;
24077 /* Our representation of array types uses "N - 1" as the
24078 TYPE_MAX_VALUE for an array with "N" elements, if "N" is
24079 not an integer constant. We cannot unify arbitrarily
24080 complex expressions, so we eliminate the MINUS_EXPRs
24081 here. */
24085 {
24088 }
24092 {
24093 /* The ARG_MAX may not be a simple MINUS_EXPR, if we are
24094 trying to unify the type of a variable with the type
24095 of a template parameter. For example:
24097 template <unsigned int N>
24098 void f (char (&) [N]);
24099 int g();
24100 void h(int i) {
24101 char a[g(i)];
24102 f(a);
24103 }
24105 Here, the type of the ARG will be "int [g(i)]", and
24106 may be a SAVE_EXPR, etc. */
24110 }
24112 /* If only one of the bounds used a MINUS_EXPR, compensate
24113 by adding one to the other bound. */
24116 integer_type_node,
24117 parm_max,
24118 integer_one_node);
24121 integer_type_node,
24122 arg_max,
24123 integer_one_node);
24127 }
24129 /* Returns whether T, a P or A in unify, is a type, template or expression. */
24133 static pa_kind_t
24135 {
24144 else
24146 }
24148 /* Deduce the value of template parameters. TPARMS is the (innermost)
24149 set of template parameters to a template. TARGS is the bindings
24150 for those template parameters, as determined thus far; TARGS may
24151 include template arguments for outer levels of template parameters
24152 as well. PARM is a parameter to a template function, or a
24153 subcomponent of that parameter; ARG is the corresponding argument.
24154 This function attempts to match PARM with ARG in a manner
24155 consistent with the existing assignments in TARGS. If more values
24156 are deduced, then TARGS is updated.
24158 Returns 0 if the type deduction succeeds, 1 otherwise. The
24159 parameter STRICT is a bitwise or of the following flags:
24161 UNIFY_ALLOW_NONE:
24162 Require an exact match between PARM and ARG.
24163 UNIFY_ALLOW_MORE_CV_QUAL:
24164 Allow the deduced ARG to be more cv-qualified (by qualification
24165 conversion) than ARG.
24166 UNIFY_ALLOW_LESS_CV_QUAL:
24167 Allow the deduced ARG to be less cv-qualified than ARG.
24168 UNIFY_ALLOW_DERIVED:
24169 Allow the deduced ARG to be a template base class of ARG,
24170 or a pointer to a template base class of the type pointed to by
24171 ARG.
24172 UNIFY_ALLOW_INTEGER:
24173 Allow any integral type to be deduced. See the TEMPLATE_PARM_INDEX
24174 case for more information.
24175 UNIFY_ALLOW_OUTER_LEVEL:
24176 This is the outermost level of a deduction. Used to determine validity
24177 of qualification conversions. A valid qualification conversion must
24178 have const qualified pointers leading up to the inner type which
24179 requires additional CV quals, except at the outer level, where const
24180 is not required [conv.qual]. It would be normal to set this flag in
24181 addition to setting UNIFY_ALLOW_MORE_CV_QUAL.
24182 UNIFY_ALLOW_OUTER_MORE_CV_QUAL:
24183 This is the outermost level of a deduction, and PARM can be more CV
24184 qualified at this point.
24185 UNIFY_ALLOW_OUTER_LESS_CV_QUAL:
24186 This is the outermost level of a deduction, and PARM can be less CV
24187 qualified at this point. */
24189 static int
24192 {
24194 tree targ;
24195 tree tparm;
24197 tsubst_flags_t complain = (explain_p
24198 ? tf_warning_or_error
24201 /* I don't think this will do the right thing with respect to types.
24202 But the only case I've seen it in so far has been array bounds, where
24203 signedness is the only information lost, and I think that will be
24204 okay. VIEW_CONVERT_EXPR can appear with class NTTP, thanks to
24205 finish_id_expression_1, and are also OK. */
24213 /* We can't deduce anything from this, but we might get all the
24214 template args from other function args. */
24220 /* If PARM uses template parameters, then we can't bail out here,
24221 even if ARG == PARM, since we won't record unifications for the
24222 template parameters. We might need them if we're trying to
24223 figure out which of two things is more specialized. */
24228 /* Handle init lists early, so the rest of the function can assume
24229 we're dealing with a type. */
24231 {
24232 tree elttype;
24237 /* We can only deduce from an initializer list argument if the
24238 parameter is std::initializer_list or an array; otherwise this
24239 is a non-deduced context. */
24244 else
24245 {
24247 /* Deduction is defined in terms of a single type, so just punt
24248 on the (bizarre) std::initializer_list<T...>. */
24251 }
24256 /* If ELTTYPE has no deducible template parms, skip deduction from
24258 else
24260 {
24268 {
24272 /* It should only be possible to get here for a call. */
24274 elt_strict |= maybe_adjust_types_for_deduction
24277 }
24280 explain_p);
24281 }
24285 {
24286 /* Also deduce from the length of the initializer list. */
24293 }
24295 /* If the std::initializer_list<T> deduction worked, replace the
24296 deduced A with std::initializer_list<A>. */
24298 {
24303 }
24305 }
24307 /* If parm and arg aren't the same kind of thing (template, type, or
24308 expression), fail early. */
24312 /* Immediately reject some pairs that won't unify because of
24313 cv-qualification mismatches. */
24316 /* It is the elements of the array which hold the cv quals of an array
24317 type, and the elements might be template type parms. We'll check
24318 when we recurse. */
24320 /* We check the cv-qualifiers when unifying with template type
24321 parameters below. We want to allow ARG `const T' to unify with
24322 PARM `T' for example, when computing which of two templates
24323 is more specialized, for example. */
24332 /* PMFs recurse at the same level, so don't strip this yet. */
24340 {
24344 /* In a type which contains a nested-name-specifier, template
24345 argument values cannot be deduced for template parameters used
24346 within the nested-name-specifier. */
24358 /* The PARM is not one we're trying to unify. Just check
24359 to see if it matches ARG. */
24360 {
24365 else
24367 }
24374 /* Check for mixed types and values. */
24382 {
24385 {
24386 /* First try to match ARG directly. */
24388 explain_p);
24390 {
24391 /* Otherwise, look for a suitable base of ARG, as below. */
24398 }
24399 }
24400 /* ARG must be constructed from a template class or a template
24401 template parameter. */
24406 /* Deduce arguments T, i from TT<T> or TT<i>. */
24412 /* If the template is a template template parameter, use the
24413 TEMPLATE_TEMPLATE_PARM for matching. */
24416 /* Fall through to deduce template name. */
24417 }
24421 {
24422 /* Deduce template name TT from TT, TT<>, TT<T> and TT<i>. */
24424 /* Simple cases: Value already set, does match or doesn't. */
24429 }
24430 else
24431 {
24432 /* If PARM is `const T' and ARG is only `int', we don't have
24433 a match unless we are allowing additional qualification.
24434 If ARG is `const int' and PARM is just `T' that's OK;
24435 that binds `const int' to `T'. */
24440 /* Consider the case where ARG is `const volatile int' and
24441 PARM is `const T'. Then, T should be `volatile int'. */
24442 arg = cp_build_qualified_type
24447 /* Simple cases: Value already set, does match or doesn't. */
24453 /* Make sure that ARG is not a variable-sized array. (Note
24454 that were talking about variable-sized arrays (like
24455 `int[n]'), rather than arrays of unknown size (like
24456 `int[]').) We'll get very confused by such a type since
24457 the bound of the array is not constant, and therefore
24458 not mangleable. Besides, such types are not allowed in
24459 ISO C++, so we can do as we please here. We do allow
24460 them for 'auto' deduction, since that isn't ABI-exposed. */
24464 /* Strip typedefs as in convert_template_argument. */
24466 }
24468 /* If ARG is a parameter pack or an expansion, we cannot unify
24469 against it unless PARM is also a parameter pack. */
24474 /* If the argument deduction results is a METHOD_TYPE,
24475 then there is a problem.
24476 METHOD_TYPE doesn't map to any real C++ type the result of
24477 the deduction cannot be of that type. */
24491 {
24492 /* The PARM is not one we're trying to unify. Just check
24493 to see if it matches ARG. */
24499 }
24505 {
24509 /* We're deducing from an array bound, the type doesn't matter.
24510 This conversion should match the one below. */
24516 }
24518 /* [temp.deduct.type] If, in the declaration of a function template
24519 with a non-type template-parameter, the non-type
24520 template-parameter is used in an expression in the function
24521 parameter-list and, if the corresponding template-argument is
24522 deduced, the template-argument type shall match the type of the
24523 template-parameter exactly, except that a template-argument
24524 deduced from an array bound may be of any integral type.
24525 The non-type parameter might use already deduced type parameters. */
24528 /* We don't have enough levels of args to do any substitution. This
24530 else
24531 {
24537 {
24540 LOOKUP_NORMAL,
24544 }
24545 }
24549 /* Template-parameter dependent expression. Just accept it for now.
24550 It will later be processed in convert_template_argument. */
24551 ;
24555 /* OK. Ignore top-level quals here because a class-type template
24559 /* Convert the ARG to the type of PARM; the deduced non-type
24560 template argument must exactly match the types of the
24561 corresponding parameter. This conversion should match the
24562 one above. */
24565 {
24566 /* We haven't deduced the type of this parameter yet. */
24568 /* We deduce from array bounds in try_array_deduction. */
24571 {
24572 /* Deduce it from the non-type argument. As above, ignore
24573 top-level quals here too. */
24578 /* Now check whether the type of this parameter is still
24579 dependent, and give up if so. */
24585 }
24586 else
24587 /* Try again later. */
24589 }
24590 else
24593 /* If ARG is a parameter pack or an expansion, we cannot unify
24594 against it unless PARM is also a parameter pack. */
24599 {
24602 }
24607 {
24608 /* A pointer-to-member constant can be unified only with
24609 another constant. */
24613 /* Just unify the class member. It would be useless (and possibly
24614 wrong, depending on the strict flags) to unify also
24615 PTRMEM_CST_CLASS, because we want to be sure that both parm and
24616 arg refer to the same variable, even if through different
24617 classes. For instance:
24619 struct A { int x; };
24620 struct B : A { };
24622 Unification of &A::x and &B::x must succeed. */
24625 }
24628 {
24632 /* [temp.deduct.call]
24634 A can be another pointer or pointer to member type that can
24635 be converted to the deduced A via a qualification
24636 conversion (_conv.qual_).
24638 We pass down STRICT here rather than UNIFY_ALLOW_NONE.
24639 This will allow for additional cv-qualification of the
24640 pointed-to types if appropriate. */
24643 /* The derived-to-base conversion only persists through one
24644 level of pointers. */
24649 }
24682 /* We have already checked cv-qualification at the top of the
24683 function. */
24687 /* As far as unification is concerned, this wins. Later checks
24688 will invalidate it if necessary. */
24691 /* Types INTEGER_CST and MINUS_EXPR can come from array bounds. */
24692 /* Type INTEGER_CST can come from ordinary constant template args. */
24705 {
24715 /* Check for pack expansions in the parameters. */
24717 {
24719 {
24721 /* We can unify against something with a trailing
24722 parameter pack. */
24724 else
24725 /* [temp.deduct.type]/9: If the template argument list of
24726 P contains a pack expansion that is not the last
24727 template argument, the entire template argument list
24728 is a non-deduced context. */
24730 }
24731 }
24733 /* If we don't have enough arguments to satisfy the parameters
24734 (not counting the pack expression at the end), or we have
24735 too many arguments for a parameter list that doesn't end in
24736 a pack expression, we can't unify. */
24742 /* Unify all of the parameters that precede the (optional)
24743 pack expression. */
24745 {
24750 }
24753 DEDUCE_EXACT,
24756 }
24764 {
24772 }
24777 {
24781 {
24782 /* First, we try to unify the PARM and ARG directly. */
24787 {
24788 /* Fallback to the special case allowed in
24789 [temp.deduct.call]:
24791 If P is a class, and P has the form
24792 template-id, then A can be a derived class of
24793 the deduced A. Likewise, if P is a pointer to
24794 a class of the form template-id, A can be a
24795 pointer to a derived class pointed to by the
24796 deduced A. */
24802 {
24803 /* Don't give the derived diagnostic if we're
24804 already dealing with the same template. */
24805 bool same_template
24811 }
24812 }
24813 }
24817 /* Perhaps PARM is something like S<U> and ARG is S<int>.
24818 Then, we should unify `int' and `U'. */
24820 else
24821 /* There's no chance of unification succeeding. */
24829 else
24831 }
24838 {
24841 tree a;
24847 /* CV qualifications for methods can never be deduced, they must
24848 match exactly. We need to check them explicitly here,
24849 because type_unification_real treats them as any other
24850 cv-qualified parameter. */
24852 && (!check_cv_quals_for_unify
24880 {
24890 else
24891 {
24894 /* Here "less cv-qual" means the deduced arg (i.e. parm) has
24895 /more/ noexcept, since function pointer conversions are the
24896 reverse of qualification conversions. */
24901 else
24903 }
24904 }
24906 {
24907 /* As for noexcept. */
24914 else
24916 }
24919 }
24922 /* Unify a pointer to member with a pointer to member function, which
24923 deduces the type of the member as a function type. */
24925 {
24926 /* Check top-level cv qualifiers */
24934 /* Determine the type of the function we are unifying against. */
24938 }
24949 /* CONST_DECL should already have been folded to its DECL_INITIAL. */
24954 /* Matched cases are handled by the ARG == PARM test above. */
24958 /* We might get a variable as a non-type template argument in parm if the
24959 corresponding parameter is type-dependent. Make any necessary
24960 adjustments based on whether arg is a reference. */
24964 {
24969 }
24970 /* Now use the normal expression code to check whether they match. */
24981 /* Cannot deduce anything from TYPEOF_TYPE, DECLTYPE_TYPE,
24982 or TRAIT_TYPE nodes. */
24986 /* Unification fails if we hit an error node. */
24991 {
25001 }
25002 /* FALLTHRU */
25005 /* An unresolved overload is a nondeduced context. */
25011 expr:
25012 /* We must be looking at an expression. This can happen with
25013 something like:
25015 template <int I>
25016 void foo(S<I>, S<I + 2>);
25018 or
25020 template<typename T>
25021 void foo(A<T, T{}>);
25023 This is a "non-deduced context":
25025 [deduct.type]
25027 The non-deduced contexts are:
25029 --A non-type template argument or an array bound in which
25030 a subexpression references a template parameter.
25032 In these cases, we assume deduction succeeded, but don't
25033 actually infer any unifications. */
25038 else
25040 }
25041 }
25042 #undef RECUR_AND_CHECK_FAILURE
25043 \f
25044 /* Note that DECL can be defined in this translation unit, if
25045 required. */
25047 static void
25049 {
25050 tree clone;
25054 }
25056 /* Called if RESULT is explicitly instantiated, or is a member of an
25057 explicitly instantiated class. */
25059 void
25061 {
25064 /* If this entity has already been written out, it's too late to
25065 make any modifications. */
25069 /* consteval functions are never emitted. */
25074 /* For anonymous namespace we don't need to do anything. */
25076 {
25079 }
25082 /* The TREE_PUBLIC flag for function declarations will have been
25083 set correctly by tsubst. */
25087 {
25090 }
25091 else
25092 {
25095 /* Always make artificials weak. */
25098 /* For WIN32 we also want to put explicit instantiations in
25099 linkonce sections. */
25104 /* If the function has already been instantiated, clear DECL_EXTERNAL,
25105 since start_preparsed_function wouldn't have if we had an earlier
25106 extern explicit instantiation. */
25108 }
25110 /* If EXTERN_P, then this function will not be emitted -- unless
25111 followed by an explicit instantiation, at which point its linkage
25112 will be adjusted. If !EXTERN_P, then this function will be
25113 emitted here. In neither circumstance do we want
25114 import_export_decl to adjust the linkage. */
25116 }
25118 /* Subroutine of more_specialized_fn: check whether TARGS is missing any
25119 important template arguments. If any are missing, we check whether
25120 they're important by using error_mark_node for substituting into any
25121 args that were used for partial ordering (the ones between ARGS and END)
25122 and seeing if it bubbles up. */
25124 static bool
25126 {
25130 {
25133 }
25135 {
25139 }
25141 }
25143 /* Given two function templates PAT1 and PAT2, return:
25145 1 if PAT1 is more specialized than PAT2 as described in [temp.func.order].
25146 -1 if PAT2 is more specialized than PAT1.
25147 0 if neither is more specialized.
25149 LEN indicates the number of parameters we should consider
25150 (defaulted parameters should not be considered).
25152 The 1998 std underspecified function template partial ordering, and
25153 DR214 addresses the issue. We take pairs of arguments, one from
25154 each of the templates, and deduce them against each other. One of
25155 the templates will be more specialized if all the *other*
25156 template's arguments deduce against its arguments and at least one
25157 of its arguments *does* *not* deduce against the other template's
25158 corresponding argument. Deduction is done as for class templates.
25159 The arguments used in deduction have reference and top level cv
25160 qualifiers removed. Iff both arguments were originally reference
25161 types *and* deduction succeeds in both directions, an lvalue reference
25162 wins against an rvalue reference and otherwise the template
25163 with the more cv-qualified argument wins for that pairing (if
25164 neither is more cv-qualified, they both are equal). Unlike regular
25165 deduction, after all the arguments have been deduced in this way,
25166 we do *not* verify the deduced template argument values can be
25167 substituted into non-deduced contexts.
25169 The logic can be a bit confusing here, because we look at deduce1 and
25170 targs1 to see if pat2 is at least as specialized, and vice versa; if we
25171 can find template arguments for pat1 to make arg1 look like arg2, that
25172 means that arg2 is at least as specialized as arg1. */
25174 int
25176 {
25189 /* Remove the this parameter from non-static member functions. If
25190 one is a non-static member function and the other is not a static
25191 member function, remove the first parameter from that function
25192 also. This situation occurs for operator functions where we
25193 locate both a member function (with this pointer) and non-member
25194 operator (with explicit first operand). */
25196 {
25201 }
25203 {
25206 {
25207 len--;
25209 }
25210 }
25212 /* If only one is a conversion operator, they are unordered. */
25216 /* Consider the return type for a conversion function */
25218 {
25221 len++;
25222 }
25224 processing_template_decl++;
25230 /* Stop when an ellipsis is seen. */
25232 {
25243 {
25244 /* When both arguments are pack expansions, we need only
25245 unify the patterns themselves. */
25249 /* This is the last comparison we need to do. */
25251 }
25254 {
25258 }
25261 {
25265 }
25271 {
25277 /* Setup the parameter vector, which contains only ARG1. */
25280 /* Setup the argument vector, which contains the remaining
25281 arguments. */
25290 /* We cannot deduce in the other direction, because ARG1 is
25291 a pack expansion but ARG2 is not. */
25293 }
25295 {
25301 /* Setup the parameter vector, which contains only ARG1. */
25304 /* Setup the argument vector, which contains the remaining
25305 arguments. */
25314 /* We cannot deduce in the other direction, because ARG2 is
25315 a pack expansion but ARG1 is not.*/
25317 }
25319 else
25320 {
25321 /* The normal case, where neither argument is a pack
25322 expansion. */
25329 }
25331 /* If we couldn't deduce arguments for tparms1 to make arg1 match
25332 arg2, then arg2 is not as specialized as arg1. */
25338 /* "If, for a given type, deduction succeeds in both directions
25339 (i.e., the types are identical after the transformations above)
25340 and both P and A were reference types (before being replaced with
25341 the type referred to above):
25342 - if the type from the argument template was an lvalue reference and
25343 the type from the parameter template was not, the argument type is
25344 considered to be more specialized than the other; otherwise,
25345 - if the type from the argument template is more cv-qualified
25346 than the type from the parameter template (as described above),
25347 the argument type is considered to be more specialized than the other;
25348 otherwise,
25349 - neither type is more specialized than the other." */
25352 {
25354 {
25357 else
25359 }
25361 {
25366 }
25367 }
25370 /* We've failed to deduce something in either direction.
25371 These must be unordered. */
25376 /* We have already processed all of the arguments in our
25377 handing of the pack expansion type. */
25382 }
25384 /* "In most cases, all template parameters must have values in order for
25385 deduction to succeed, but for partial ordering purposes a template
25386 parameter may remain without a value provided it is not used in the
25387 types being used for partial ordering."
25389 Thus, if we are missing any of the targs1 we need to substitute into
25390 origs1, then pat2 is not as specialized as pat1. This can happen when
25391 there is a nondeduced context. */
25397 processing_template_decl--;
25399 /* If both deductions succeed, the partial ordering selects the more
25400 constrained template. */
25401 /* P2113: If the corresponding template-parameters of the
25402 template-parameter-lists are not equivalent ([temp.over.link]) or if
25403 the function parameters that positionally correspond between the two
25404 templates are not of the same type, neither template is more
25405 specialized than the other. */
25410 {
25416 }
25418 /* All things being equal, if the next argument is a pack expansion
25419 for one function but not for the other, prefer the
25420 non-variadic function. FIXME this is bogus; see c++/41958. */
25424 {
25427 }
25433 else
25435 }
25437 /* Determine which of two partial specializations of TMPL is more
25438 specialized.
25440 PAT1 is a TREE_LIST whose TREE_VALUE is the TEMPLATE_DECL corresponding
25441 to the first partial specialization. The TREE_PURPOSE is the
25442 innermost set of template parameters for the partial
25443 specialization. PAT2 is similar, but for the second template.
25445 Return 1 if the first partial specialization is more specialized;
25446 -1 if the second is more specialized; 0 if neither is more
25447 specialized.
25449 See [temp.class.order] for information about determining which of
25450 two templates is more specialized. */
25452 static int
25454 {
25455 tree targs;
25464 /* Just like what happens for functions, if we are ordering between
25465 different template specializations, we may encounter dependent
25466 types in the arguments, and we need our dependency check functions
25467 to behave correctly. */
25471 {
25474 }
25478 {
25481 }
25484 /* If both deductions succeed, the partial ordering selects the more
25485 constrained template. */
25489 /* In the case of a tie where at least one of the templates
25490 has a parameter pack at the end, the template with the most
25491 non-packed parameters wins. */
25493 && any_deductions
25496 {
25502 /* We don't count the pack expansion at the end. */
25512 }
25515 }
25517 /* Return the template arguments that will produce the function signature
25518 DECL from the function template FN, with the explicit template
25519 arguments EXPLICIT_ARGS. If CHECK_RETTYPE is true, the return type must
25520 also match. Return NULL_TREE if no satisfactory arguments could be
25521 found. */
25523 static tree
25525 {
25529 tree decl_arg_types;
25532 tree arg;
25536 /* Never do unification on the 'this' parameter. */
25558 }
25560 /* Return the innermost template arguments that, when applied to a partial
25561 specialization SPEC_TMPL of TMPL, yield the ARGS.
25563 For example, suppose we have:
25565 template <class T, class U> struct S {};
25566 template <class T> struct S<T*, int> {};
25568 Then, suppose we want to get `S<double*, int>'. SPEC_TMPL will be the
25569 partial specialization and the ARGS will be {double*, int}. The resulting
25570 vector will be {double}, indicating that `T' is bound to `double'. */
25572 static tree
25574 {
25576 tree spec_args
25579 tree deduced_args;
25580 tree innermost_deduced_args;
25584 {
25588 innermost_deduced_args);
25589 }
25590 else
25594 again:
25603 {
25605 {
25611 }
25613 }
25616 {
25619 }
25621 /* Verify that nondeduced template arguments agree with the type
25622 obtained from argument deduction.
25624 For example:
25626 struct A { typedef int X; };
25627 template <class T, class U> struct C {};
25628 template <class T> struct C<T, typename T::X> {};
25630 Then with the instantiation `C<A, int>', we can deduce that
25631 `T' is `A' but unify () does not check whether `typename T::X'
25632 is `int'. */
25643 /* We only need to check the innermost arguments; the other
25644 arguments will always agree. */
25649 /* Now that we have bindings for all of the template arguments,
25650 ensure that the arguments deduced for the template template
25651 parameters have compatible template parameter lists. See the use
25652 of template_template_parm_bindings_ok_p in fn_type_unification
25653 for more information. */
25658 }
25660 // Compare two function templates T1 and T2 by deducing bindings
25661 // from one against the other. If both deductions succeed, compare
25662 // constraints to see which is more constrained.
25663 static int
25665 {
25670 {
25673 }
25676 {
25679 }
25681 // If both deductions succeed, then one may be more constrained.
25686 }
25688 /* TEMPLATES is a TREE_LIST. Each TREE_VALUE is a TEMPLATE_DECL.
25689 Return the TREE_LIST node with the most specialized template, if
25690 any. If there is no most specialized template, the error_mark_node
25691 is returned.
25693 Note that this function does not look at, or modify, the
25694 TREE_PURPOSE or TREE_TYPE of any of the nodes. Since the node
25695 returned is one of the elements of INSTANTIATIONS, callers may
25696 store information in the TREE_PURPOSE or TREE_TYPE of the nodes,
25697 and retrieve it from the value returned. */
25699 tree
25701 {
25708 {
25714 {
25715 /* Equally specialized, move to next function. If there
25716 is no next function, nothing's most specialized. */
25721 }
25722 }
25725 /* Now verify that champ is better than everything earlier in the
25726 instantiation list. */
25729 {
25732 }
25733 }
25735 processing_template_decl--;
25741 }
25743 /* If DECL is a specialization of some template, return the most
25744 general such template. Otherwise, returns NULL_TREE.
25746 For example, given:
25748 template <class T> struct S { template <class U> void f(U); };
25750 if TMPL is `template <class U> void S<int>::f(U)' this will return
25751 the full template. This function will not trace past partial
25752 specializations, however. For example, given in addition:
25754 template <class T> struct S<T*> { template <class U> void f(U); };
25756 if TMPL is `template <class U> void S<int*>::f(U)' this will return
25757 `template <class T> template <class U> S<T*>::f(U)'. */
25759 tree
25761 {
25763 {
25766 /* The TI_TEMPLATE can be an IDENTIFIER_NODE for a
25767 template friend, or a FIELD_DECL for a capture pack. */
25770 }
25775 /* Look for more and more general templates. */
25777 {
25778 /* The DECL_TI_TEMPLATE can be an IDENTIFIER_NODE in some cases.
25779 (See cp-tree.h for details.) */
25788 /* Stop if we run into an explicitly specialized class template. */
25795 }
25798 }
25800 /* Return the most specialized of the template partial specializations
25801 which can produce TARGET, a specialization of some class or variable
25802 template. The value returned is a TEMPLATE_INFO; the TI_TEMPLATE is a
25803 TEMPLATE_DECL node corresponding to the partial specialization, while
25804 the TI_ARGS is the set of template arguments that must be substituted
25805 into the template pattern in order to generate TARGET. The result is
25806 cached in the TI_PARTIAL_INFO of the corresponding TEMPLATE_INFO unless
25807 RECHECKING is true.
25809 If the choice of partial specialization is ambiguous, a diagnostic
25810 is issued, and the error_mark_node is returned. If there are no
25811 partial specializations matching TARGET, then NULL_TREE is
25812 returned, indicating that the primary template should be used. */
25814 tree
25817 {
25821 {
25826 }
25828 {
25832 }
25834 {
25839 }
25840 else
25847 && tinfo
25854 /* There are no partial specializations of this template. */
25860 /* For determining which partial specialization to use, only the
25861 innermost args are interesting. */
25864 {
25867 }
25869 /* The caller hasn't called push_to_top_level yet, but we need
25870 get_partial_spec_bindings to be done in non-template context so that we'll
25871 fully resolve everything. */
25872 processing_template_decl_sentinel ptds;
25876 {
25879 tree spec_tmpl;
25881 {
25882 /* Substitute in the template args from the enclosing class. */
25888 }
25889 else
25894 {
25898 /* Keep the candidate only if its constraints are satisfied. */
25901 }
25902 }
25910 {
25913 ;
25914 else
25915 {
25917 {
25920 {
25923 }
25924 }
25926 }
25927 }
25931 {
25934 {
25937 }
25938 }
25941 {
25948 else
25952 {
25957 }
25960 }
25966 }
25968 /* Explicitly instantiate DECL. */
25970 void
25972 {
25977 /* An error occurred, for which grokdeclarator has already issued
25978 an appropriate message. */
25981 {
25984 }
25986 {
25989 else
25992 }
25998 {
25999 /* There is an asymmetry here in the way VAR_DECLs and
26000 FUNCTION_DECLs are handled by grokdeclarator. In the case of
26001 the latter, the DECL we get back will be marked as a
26002 template instantiation, and the appropriate
26003 DECL_TEMPLATE_INFO will be set up. This does not happen for
26004 VAR_DECLs so we do the lookup here. Probably, grokdeclarator
26005 should handle VAR_DECLs as it currently handles
26006 FUNCTION_DECLs. */
26008 {
26011 }
26014 {
26017 }
26019 {
26024 }
26025 }
26027 {
26030 }
26031 else
26034 /* Check for various error cases. Note that if the explicit
26035 instantiation is valid the RESULT will currently be marked as an
26036 *implicit* instantiation; DECL_EXPLICIT_INSTANTIATION is not set
26037 until we get here. */
26040 {
26041 /* DR 259 [temp.spec].
26043 Both an explicit instantiation and a declaration of an explicit
26044 specialization shall not appear in a program unless the explicit
26045 instantiation follows a declaration of the explicit specialization.
26047 For a given set of template parameters, if an explicit
26048 instantiation of a template appears after a declaration of an
26049 explicit specialization for that template, the explicit
26050 instantiation has no effect. */
26052 }
26054 {
26055 /* [temp.spec]
26057 No program shall explicitly instantiate any template more
26058 than once.
26060 We check DECL_NOT_REALLY_EXTERN so as not to complain when
26061 the first instantiation was `extern' and the second is not,
26062 and EXTERN_P for the opposite case. */
26065 /* If an "extern" explicit instantiation follows an ordinary
26066 explicit instantiation, the template is instantiated. */
26069 }
26071 {
26074 }
26076 {
26079 }
26082 ;
26084 {
26087 "ISO C++ 1998 forbids the use of %<extern%> on explicit "
26090 }
26091 else
26099 }
26101 static void
26103 {
26109 {
26112 }
26113 }
26115 /* Perform an explicit instantiation of template class T. STORAGE, if
26116 non-null, is the RID for extern, inline or static. COMPLAIN is
26117 nonzero if this is called from the parser, zero if called recursively,
26118 since the standard is unclear (as detailed below). */
26120 void
26122 {
26124 {
26128 else
26131 }
26136 {
26139 t);
26141 }
26143 /* At most one of these will be true. */
26149 {
26151 {
26154 "ISO C++ 1998 forbids the use of %<extern%> on "
26156 }
26157 else
26159 "ISO C++ forbids the use of %qE"
26168 else
26170 storage);
26171 }
26174 /* DR 259 [temp.spec].
26176 Both an explicit instantiation and a declaration of an explicit
26177 specialization shall not appear in a program unless the
26178 explicit instantiation follows a declaration of the explicit
26179 specialization.
26181 For a given set of template parameters, if an explicit
26182 instantiation of a template appears after a declaration of an
26183 explicit specialization for that template, the explicit
26184 instantiation has no effect. */
26188 {
26189 /* We've already instantiated the template. */
26191 /* [temp.spec]
26193 No program shall explicitly instantiate any template more
26194 than once.
26196 If EXTERN_P then this is ok. */
26202 }
26210 /* In contrast to implicit instantiation, where only the
26211 declarations, and not the definitions, of members are
26212 instantiated, we have here:
26214 [temp.explicit]
26216 An explicit instantiation that names a class template
26217 specialization is also an explicit instantiation of the same
26218 kind (declaration or definition) of each of its members (not
26219 including members inherited from base classes and members
26220 that are templates) that has not been previously explicitly
26221 specialized in the translation unit containing the explicit
26222 instantiation, provided that the associated constraints, if
26223 any, of that member are satisfied by the template arguments
26224 of the explicit instantiation. */
26228 && !static_p
26232 {
26237 }
26239 {
26245 }
26246 }
26248 /* Given a function DECL, which is a specialization of TMPL, modify
26249 DECL to be a re-instantiation of TMPL with the same template
26250 arguments. TMPL should be the template into which tsubst'ing
26251 should occur for DECL, not the most general template.
26253 One reason for doing this is a scenario like this:
26255 template <class T>
26256 void f(const T&, int i);
26258 void g() { f(3, 7); }
26260 template <class T>
26261 void f(const T& t, const int i) { }
26263 Note that when the template is first instantiated, with
26264 instantiate_template, the resulting DECL will have no name for the
26265 first parameter, and the wrong type for the second. So, when we go
26266 to instantiate the DECL, we regenerate it. */
26268 static void
26270 {
26271 /* The arguments used to instantiate DECL, from the most general
26272 template. */
26275 /* Make sure that we can see identifiers, and compute access correctly. */
26279 {
26280 tree specs;
26284 /* Don't bother with this for unique friends that can't be redeclared and
26285 might change type if regenerated (PR69836). */
26289 /* Use the source location of the definition. */
26297 /* Instantiate a dynamic exception-specification. noexcept will be
26298 handled below. */
26301 {
26307 specs);
26308 }
26310 /* Merge parameter declarations. */
26314 {
26321 }
26324 {
26325 /* If we're regenerating a specialization, the contracts will have
26326 been copied from the most general template. Replace those with
26327 the ones from the actual specialization. */
26330 {
26333 }
26336 }
26338 /* Merge additional specifiers from the CODE_PATTERN. */
26344 }
26346 {
26355 }
26356 else
26359 done:
26361 }
26363 /* Return the TEMPLATE_DECL into which DECL_TI_ARGS(DECL) should be
26364 substituted to get DECL. */
26366 tree
26368 {
26371 /* Set TMPL to the template whose DECL_TEMPLATE_RESULT is the pattern
26372 for the instantiation. This is not always the most general
26373 template. Consider, for example:
26375 template <class T>
26376 struct S { template <class U> void f();
26377 template <> void f<int>(); };
26379 and an instantiation of S<double>::f<int>. We want TD to be the
26380 specialization S<T>::f<int>, not the more general S<T>::f<U>. */
26382 more general template. */
26384 /* We must also deal with friend templates. Given:
26386 template <class T> struct S {
26387 template <class U> friend void f() {};
26388 };
26390 S<int>::f<U> say, is not an instantiation of S<T>::f<U>,
26391 so far as the language is concerned, but that's still
26392 where we get the pattern for the instantiation from. On
26393 other hand, if the definition comes outside the class, say:
26395 template <class T> struct S {
26396 template <class U> friend void f();
26397 };
26398 template <class U> friend void f() {}
26400 we don't need to look any further. That's what the check for
26401 DECL_INITIAL is for. */
26405 {
26406 /* The present template, TD, should not be a definition. If it
26407 were a definition, we should be using it! Note that we
26408 cannot restructure the loop to just keep going until we find
26409 a template with a definition, since that might go too far if
26410 a specialization was declared, but not defined. */
26412 /* Fetch the more general template. */
26414 }
26417 }
26419 /* Returns true if we need to instantiate this template instance even if we
26420 know we aren't going to emit it. */
26422 bool
26424 {
26425 /* We always instantiate inline functions so that we can inline them. An
26426 explicit instantiation declaration prohibits implicit instantiation of
26427 non-inline functions. With high levels of optimization, we would
26428 normally inline non-inline functions -- but we're not allowed to do
26429 that for "extern template" functions. Therefore, we check
26430 DECL_DECLARED_INLINE_P, rather than possibly_inlined_p. */
26434 /* And we need to instantiate static data members so that
26435 their initializers are available in integral constant
26436 expressions. */
26439 }
26441 /* If FN has a noexcept-specifier that hasn't been instantiated yet,
26442 instantiate it now, modifying TREE_TYPE (fn). Returns false on
26443 error, true otherwise. */
26445 bool
26447 {
26451 /* Don't instantiate a noexcept-specification from template context. */
26461 {
26463 /* We're in start_preparsed_function, keep going. */
26470 }
26481 /* For a member friend template we can get a TEMPLATE_DECL. Let's use
26482 its FUNCTION_DECL for the rest of this function -- push_access_scope
26483 doesn't accept TEMPLATE_DECLs. */
26485 {
26488 }
26491 {
26496 }
26498 {
26502 {
26505 /* This might have failed because of an unparsed DMI, so
26506 let's try again later. */
26508 }
26510 {
26511 /* If hash_set::add returns true, the element was already there. */
26516 fn);
26518 }
26520 {
26528 {
26529 /* If needed, set current_class_ptr for the benefit of
26530 tsubst_copy/PARM_DECL. */
26535 }
26537 /* If this function is represented by a TEMPLATE_DECL, then
26538 the deferred noexcept-specification might still contain
26539 dependent types, even after substitution. And we need the
26540 dependency check functions to work in build_noexcept_spec. */
26544 /* Do deferred instantiation of the noexcept-specifier. */
26549 /* Build up the noexcept-specification. */
26559 }
26560 else
26565 }
26568 {
26569 /* This failed with a hard error, so let's go with false. */
26572 }
26579 }
26581 /* We're starting to process the function INST, an instantiation of PATTERN;
26582 add their parameters to local_specializations. */
26584 void
26586 {
26590 {
26594 }
26596 {
26598 {
26601 }
26602 else
26603 {
26604 /* Register the (value) argument pack as a specialization of
26605 TMPL_PARM, then move on. */
26608 }
26609 }
26611 }
26613 /* Instantiate the body of D using PATTERN with ARGS. We have
26614 already determined PATTERN is the correct template to use.
26615 NESTED_P is true if this is a nested function, in which case
26616 PATTERN will be a FUNCTION_DECL not a TEMPLATE_DECL. */
26618 static void
26620 {
26625 {
26628 }
26629 else
26630 /* Only OMP reductions are nested. */
26642 {
26643 /* The variable might be a lambda's extra scope, and that
26644 lambda's visibility depends on D's. */
26647 }
26649 /* Mark D as instantiated so that recursive calls to
26650 instantiate_decl do not try to instantiate it again. */
26654 /* Regenerate the declaration in case the template has been modified
26655 by a subsequent redeclaration. */
26658 /* We already set the file and line above. Reset them now in case
26659 they changed as a result of calling regenerate_decl_from_template. */
26663 {
26664 /* Clear out DECL_RTL; whatever was there before may not be right
26665 since we've reset the type of the declaration. */
26669 /* The initializer is placed in DECL_INITIAL by
26670 regenerate_decl_from_template so we don't need to
26671 push/pop_access_scope again here. Pull it out so that
26672 cp_finish_decl can process it. */
26678 /* Clear DECL_EXTERNAL so that cp_finish_decl will process the
26679 initializer. That function will defer actual emission until
26680 we have a chance to determine linkage. */
26683 /* Enter the scope of D so that access-checking works correctly. */
26693 }
26697 {
26698 /* Set up the list of local specializations. */
26702 /* Set up context. */
26705 else
26706 {
26710 }
26712 /* Create substitution entries for the parameters. */
26715 /* Substitute into the body of the function. */
26719 else
26720 {
26724 /* Set the current input_location to the end of the function
26725 so that finish_function knows where we are. */
26726 input_location
26729 /* Remember if we saw an infinite loop in the template. */
26730 current_function_infinite_loop
26732 }
26734 /* Finish the function. */
26737 else
26738 {
26741 }
26745 }
26747 /* We're not deferring instantiation any more. */
26755 }
26757 /* Produce the definition of D, a _DECL generated from a template. If
26758 DEFER_OK is true, then we don't have to actually do the
26759 instantiation now; we just have to do it sometime. Normally it is
26760 an error if this is an explicit instantiation but D is undefined.
26761 EXPL_INST_CLASS_MEM_P is true iff D is a member of an explicitly
26762 instantiated class template. */
26764 tree
26766 {
26768 tree gen_args;
26769 tree args;
26770 tree td;
26771 tree code_pattern;
26772 tree spec;
26773 tree gen_tmpl;
26781 /* This function should only be used to instantiate templates for
26782 functions and static member variables. */
26785 /* A concept is never instantiated. */
26791 /* We may have a pending instantiation of D itself. */
26794 /* Variables are never deferred; if instantiation is required, they
26795 are instantiated right away. That allows for better code in the
26796 case that an expression refers to the value of the variable --
26797 if the variable has a constant value the referring expression can
26798 take advantage of that fact. */
26802 /* Don't instantiate cloned functions. Instead, instantiate the
26803 functions they cloned. */
26812 /* D has already been instantiated or explicitly specialized, so
26813 there's nothing for us to do here.
26815 It might seem reasonable to check whether or not D is an explicit
26816 instantiation, and, if so, stop here. But when an explicit
26817 instantiation is deferred until the end of the compilation,
26818 DECL_EXPLICIT_INSTANTIATION is set, even though we still need to do
26819 the instantiation. */
26822 /* Check to see whether we know that this template will be
26823 instantiated in some other file, as with "extern template"
26824 extension. */
26827 /* In general, we do not instantiate such templates. */
26834 /* We should already have the extra args. */
26838 /* And what's in the hash table should match D. */
26840 == d
26843 /* This needs to happen before any tsubsting. */
26849 /* Set TD to the template whose DECL_TEMPLATE_RESULT is the pattern
26850 for the instantiation. */
26855 {
26856 /* Look up an explicit specialization, if any. */
26859 {
26862 }
26863 }
26867 /* We should never be trying to instantiate a member of a class
26868 template or partial specialization. */
26873 /* In the case of a friend template whose definition is provided
26874 outside the class, we may have too many arguments. Drop the
26875 ones we don't need. The same is true for specializations. */
26876 args = get_innermost_template_args
26880 {
26886 }
26887 else
26888 {
26892 else
26894 }
26896 /* We may be in the middle of deferred access check. Disable it now. */
26899 /* Unless an explicit instantiation directive has already determined
26900 the linkage of D, remember that a definition is available for
26901 this entity. */
26911 /* If D is a member of an explicitly instantiated class template,
26912 and no definition is available, treat it like an implicit
26913 instantiation. */
26916 {
26917 /* Leave linkage flags alone on instantiations with anonymous
26918 visibility. */
26920 {
26923 }
26925 }
26927 /* Defer all other templates, unless we have been explicitly
26928 forbidden from doing so. */
26930 template. */
26931 ! pattern_defined
26932 /* If it's OK to postpone instantiation, do so. */
26933 || defer_ok
26934 /* If this is a static data member that will be defined
26935 elsewhere, we don't want to instantiate the entire data
26936 member, but we do want to instantiate the initializer so that
26937 we can substitute that elsewhere. */
26939 /* Handle here a deleted function too, avoid generating
26940 its body (c++/61080). */
26942 {
26943 /* The definition of the static data member is now required so
26944 we must substitute the initializer. */
26948 {
26949 tree ns;
26950 tree init;
26959 args,
26961 /* If instantiating the initializer involved instantiating this
26962 again, don't call cp_finish_decl twice. */
26964 {
26965 /* Make sure the initializer is still constant, in case of
26966 circular dependency (template/instantiate6.C). */
26967 const_init
26971 }
26975 }
26977 /* We restore the source position here because it's used by
26978 add_pending_template. */
26984 /* [temp.explicit]
26986 The definition of a non-exported function template, a
26987 non-exported member function template, or a non-exported
26988 member function or static data member of a class template
26989 shall be present in every translation unit in which it is
26990 explicitly instantiated. */
26994 /* If we're in unevaluated context, we just wanted to get the
26995 constant value; this isn't an odr use, so don't queue
26996 a full instantiation. */
26998 /* ??? Historically, we have instantiated inline functions, even
26999 when marked as "extern template". */
27002 }
27003 else
27004 {
27009 }
27018 }
27020 /* Run through the list of templates that we wish we could
27021 instantiate, and instantiate any we can. RETRIES is the
27022 number of times we retry pending template instantiation. */
27024 void
27026 {
27030 /* Instantiating templates may trigger vtable generation. This in turn
27031 may require further template instantiations. We place a limit here
27032 to avoid infinite loop. */
27034 {
27038 "template instantiation depth exceeds maximum of %d"
27039 " instantiating %q+D, possibly from virtual table generation"
27043 /* Pretend that we defined it. */
27046 }
27048 do
27049 {
27054 {
27059 {
27061 {
27076 }
27079 }
27080 else
27081 {
27084 {
27085 instantiation
27091 }
27095 }
27098 {
27099 /* If INSTANTIATION has been instantiated, then we don't
27100 need to consider it again in the future. */
27105 }
27106 else
27107 {
27110 }
27113 }
27115 }
27119 }
27121 /* Substitute ARGVEC into T, which is a list of initializers for
27122 either base class or a non-static data member. The TREE_PURPOSEs
27123 are DECLs, and the TREE_VALUEs are the initializer values. Used by
27124 instantiate_decl. */
27126 static tree
27128 {
27133 {
27134 tree decl;
27135 tree init;
27141 {
27142 tree expr;
27143 tree arg;
27145 /* Expand the base class expansion type into separate base
27146 classes. */
27148 tf_warning_or_error,
27149 NULL_TREE);
27153 /* We'll be building separate TREE_LISTs of arguments for
27154 each base. */
27160 /* Build a dummy EXPR_PACK_EXPANSION that will be used to
27161 expand each argument in the TREE_VALUE of t. */
27168 /* VOID_TYPE_NODE is used to indicate
27169 value-initialization. */
27170 {
27173 }
27174 else
27175 {
27176 /* Substitute parameter packs into each argument in the
27177 TREE_LIST. */
27180 {
27181 tree expanded_exprs;
27183 /* Expand the argument. */
27184 tree value;
27187 else
27188 {
27191 }
27192 expanded_exprs
27194 tf_warning_or_error,
27195 NULL_TREE);
27199 /* Prepend each of the expanded expressions to the
27200 corresponding TREE_LIST in EXPANDED_ARGUMENTS. */
27208 else
27213 }
27216 /* Reverse all of the TREE_LISTs in EXPANDED_ARGUMENTS,
27217 since we built them backwards. */
27219 {
27222 }
27223 }
27224 }
27227 {
27229 {
27233 }
27234 else
27235 {
27236 tree tmp;
27240 else
27254 /* If we had an initializer but it instantiated to nothing,
27255 value-initialize the object. This will only occur when
27256 the initializer was a pack expansion where the parameter
27257 packs used in that expansion were of length zero. */
27260 }
27264 {
27266 decl);
27268 }
27269 /* Look for a target constructor. */
27273 {
27276 {
27280 }
27282 }
27285 {
27287 /* Carry over the dummy TREE_TYPE node containing the source
27288 location. */
27292 }
27293 }
27294 }
27296 }
27298 /* Instantiate an enumerated type. TAG is the template type, NEWTAG
27299 is the instantiation (which should have been created with
27300 start_enum) and ARGS are the template arguments to use. */
27302 static void
27304 {
27305 tree e;
27311 {
27312 tree value;
27315 /* Note that in a template enum, the TREE_VALUE is the
27316 CONST_DECL, not the corresponding INTEGER_CST. */
27320 /* Give this enumeration constant the correct access. */
27323 /* Actually build the enumerator itself. Here we're assuming that
27324 enumerators can't have dependent attributes. */
27328 /* Attribute deprecated without an argument isn't sticky: it'll
27329 melt into a tree flag, so we need to propagate the flag here,
27330 since we just created a new enumerator. */
27333 }
27345 }
27347 /* DECL is a FUNCTION_DECL that is a template specialization. Return
27348 its type -- but without substituting the innermost set of template
27349 arguments. So, innermost set of template parameters will appear in
27350 the type. */
27352 tree
27354 {
27355 /* For a function, DECL_TI_TEMPLATE is partially instantiated. */
27357 }
27359 /* Return truthvalue if we're processing a template different from
27360 the last one involved in diagnostics. */
27361 bool
27363 {
27365 }
27367 /* Remember current template involved in diagnostics. */
27368 void
27370 {
27372 }
27376 {
27378 }
27380 /* Return TRUE if current_function_decl is being instantiated, false
27381 otherwise. */
27383 bool
27385 {
27389 }
27391 /* [temp.param] Check that template non-type parm TYPE is of an allowable
27392 type. Return false for ok, true for disallowed. Issue error and
27393 inform messages under control of COMPLAIN. */
27395 static bool
27397 {
27408 {
27410 {
27415 }
27417 }
27422 /* Fall through; before C++11 alias templates, a bound ttp
27425 /* Any other wildcard type not already handled above is allowed. */
27432 {
27440 {
27441 auto_diagnostic_group d;
27445 }
27447 }
27449 {
27454 }
27457 {
27460 else
27462 type);
27463 }
27465 }
27467 /* Returns true iff the noexcept-specifier for TYPE is value-dependent. */
27469 static bool
27471 {
27474 /* Treat DEFERRED_NOEXCEPT as non-dependent, since it doesn't
27475 affect overload resolution and treating it as dependent breaks
27476 things. Same for an unparsed noexcept expression. */
27483 }
27485 /* Returns TRUE if TYPE is dependent, in the sense of [temp.dep.type].
27486 Assumes that TYPE really is a type, and not the ERROR_MARK_NODE.*/
27488 static bool
27490 {
27491 tree scope;
27493 /* [temp.dep.type]
27495 A type is dependent if it is:
27497 -- a template parameter. Template template parameters are types
27498 for us (since TYPE_P holds true for them) so we handle
27499 them here. */
27503 /* -- a qualified-id with a nested-name-specifier which contains a
27504 class-name that names a dependent type or whose unqualified-id
27505 names a dependent type. */
27509 /* An alias template specialization can be dependent even if the
27510 resulting type is not. */
27514 /* -- a cv-qualified type where the cv-unqualified type is
27515 dependent.
27516 No code is necessary for this bullet; the code below handles
27517 cv-qualified types, and we don't want to strip aliases with
27518 TYPE_MAIN_VARIANT because of DR 1558. */
27519 /* -- a compound type constructed from any dependent type. */
27527 {
27528 tree arg_type;
27533 arg_type;
27539 /* A value-dependent noexcept-specifier makes the type dependent. */
27542 }
27543 /* -- an array type constructed from any dependent type or whose
27544 size is specified by a constant expression that is
27545 value-dependent.
27547 We checked for type- and value-dependence of the bounds in
27548 compute_array_index_type, so TYPE_DEPENDENT_P is already set. */
27550 {
27555 }
27557 /* -- a template-id in which either the template name is a template
27558 parameter ... */
27561 /* ... or any of the template arguments is a dependent type or
27562 an expression that is type-dependent or value-dependent. */
27564 && (any_dependent_template_arguments_p
27568 /* All TYPEOF_TYPEs, DECLTYPE_TYPEs, and TRAIT_TYPEs are
27569 dependent; if the argument of the `typeof' expression is not
27570 type-dependent, then it should already been have resolved. */
27576 /* A template argument pack is dependent if any of its packed
27577 arguments are. */
27579 {
27584 }
27586 /* All TYPE_PACK_EXPANSIONs are dependent, because parameter packs must
27587 be template parameters. */
27597 /* The standard does not specifically mention types that are local
27598 to template functions or local classes, but they should be
27599 considered dependent too. For example:
27601 template <int I> void f() {
27602 enum E { a = I };
27603 S<sizeof (E)> s;
27604 }
27606 The size of `E' cannot be known until the value of `I' has been
27607 determined. Therefore, `E' must be considered dependent. */
27611 /* Don't use type_dependent_expression_p here, as it can lead
27612 to infinite recursion trying to determine whether a lambda
27613 nested in a lambda is dependent (c++/47687). */
27617 && (any_dependent_template_arguments_p
27621 /* Other types are non-dependent. */
27623 }
27625 /* Returns TRUE if TYPE is dependent, in the sense of
27626 [temp.dep.type]. Note that a NULL type is considered dependent. */
27628 bool
27630 {
27631 /* If there are no template parameters in scope, then there can't be
27632 any dependent types. */
27634 {
27635 /* If we are not processing a template, then nobody should be
27636 providing us with a dependent type. */
27640 }
27642 /* If the type is NULL, we have not computed a type for the entity
27643 in question; in that case, the type is dependent. */
27647 /* Erroneous types can be considered non-dependent. */
27651 /* If we have not already computed the appropriate value for TYPE,
27652 do so now. */
27654 {
27657 }
27660 }
27662 /* Returns TRUE if SCOPE is a dependent scope, in which we can't do any
27663 lookup. In other words, a dependent type that is not the current
27664 instantiation. */
27666 bool
27668 {
27671 }
27673 /* True if we might find more declarations in SCOPE during instantiation than
27674 we can when parsing the template. */
27676 bool
27678 {
27680 }
27682 /* T is a SCOPE_REF. Return whether it represents a non-static member of
27683 an unknown base of 'this' (and is therefore instantiation-dependent). */
27685 static bool
27687 {
27704 }
27706 /* T is a SCOPE_REF; return whether we need to consider it
27707 instantiation-dependent so that we can check access at instantiation
27708 time even though we know which member it resolves to. */
27710 static bool
27712 {
27720 else
27722 }
27724 /* Returns TRUE if the EXPRESSION is value-dependent, in the sense of
27725 [temp.dep.constexpr]. EXPRESSION is already known to be a constant
27726 expression. */
27728 /* Note that this predicate is not appropriate for general expressions;
27729 only constant expressions (that satisfy potential_constant_expression)
27730 can be tested for value dependence. */
27732 bool
27734 {
27738 /* A type-dependent expression is also value-dependent. */
27743 {
27745 /* A dependent member function of the current instantiation. */
27749 /* A dependent member function of the current instantiation. */
27756 /* A name that has not been looked up -- must be dependent. */
27760 /* A non-type template parm. */
27764 /* A non-type template parm. */
27770 /* A constant with literal type and is initialized
27771 with an expression that is value-dependent. */
27775 {
27778 /* __PRETTY_FUNCTION__ inside a template function is dependent
27779 on the name of the function. */
27781 /* It might be used in a template, but not a template
27782 function, in which case its DECL_VALUE_EXPR will be
27783 "top level". */
27786 }
27788 /* FIXME cp_finish_decl doesn't fold reference initializers. */
27790 /* We have a constexpr variable and we're processing a template. When
27791 there's lifetime extension involved (for which finish_compound_literal
27792 used to create a temporary), we'll not be able to evaluate the
27793 variable until instantiating, so pretend it's value-dependent. */
27805 /* These expressions are value-dependent if the type to which
27806 the cast occurs is dependent or the expression being casted
27807 is value-dependent. */
27808 {
27814 /* A functional cast has a list of operands. */
27817 {
27818 /* If there are no operands, it must be an expression such
27819 as "int()". This should not happen for aggregate types
27820 because it would form non-constant expressions. */
27825 }
27835 }
27840 /* FALLTHRU */
27843 /* A `sizeof' expression is value-dependent if the operand is
27844 type-dependent or is a pack expansion. */
27853 /* An 'encode' expression is value-dependent if the operand is
27854 type-dependent. */
27863 /* All instantiation-dependent expressions should also be considered
27864 value-dependent. */
27872 /* A NONTYPE_ARGUMENT_PACK is value-dependent if any packed argument
27873 is value-dependent. */
27880 {
27896 }
27907 {
27911 }
27914 /* Treat all requires-expressions as value-dependent so
27915 we don't try to fold them. */
27922 {
27929 {
27931 /* In a call to a constexpr member function, look through the
27932 implicit ADDR_EXPR on the object argument so that it doesn't
27933 cause the call to be considered value-dependent. We also
27934 look through it in potential_constant_expression. */
27941 }
27943 }
27950 {
27952 tree val;
27959 }
27962 /* Treat a GNU statement expression as dependent to avoid crashing
27963 under instantiate_non_dependent_expr; it can't be constant. */
27968 /* The second operand is a type, which type_dependent_expression_p
27969 (and therefore value_dependent_expression_p) doesn't want to see. */
27975 /* A constant expression is value-dependent if any subexpression is
27976 value-dependent. */
27978 {
27985 {
27989 {
27992 /* In some cases, some of the operands may be missing.
27993 (For example, in the case of PREDECREMENT_EXPR, the
27994 amount to increment by may be missing.) That doesn't
27995 make the expression dependent. */
27998 }
27999 }
28003 }
28005 }
28007 /* The expression is not value-dependent. */
28009 }
28011 /* Returns TRUE if the EXPRESSION is type-dependent, in the sense of
28012 [temp.dep.expr]. Note that an expression with no type is
28013 considered dependent. Other parts of the compiler arrange for an
28014 expression with type-dependent subexpressions to have no type, so
28015 this function doesn't have to be fully recursive. */
28017 bool
28019 {
28030 /* An unresolved name is always dependent. */
28036 /* A lambda-expression in template context is dependent. dependent_type_p is
28037 true for a lambda in the scope of a class or function template, but that
28038 doesn't cover all template contexts, like a default template argument. */
28042 /* A fold expression is type-dependent. */
28049 /* Some expression forms are never type-dependent. */
28062 /* The types of these expressions depends only on the type to which
28063 the cast occurs. */
28072 /* The types of these expressions depends only on the type created
28073 by the expression. */
28076 {
28077 /* For NEW_EXPR tree nodes created inside a template, either
28078 the object type itself or a TREE_LIST may appear as the
28079 operand 1. */
28082 /* This is an array type. We need to check array dimensions
28083 as well. */
28085 || value_dependent_expression_p
28087 /* Array type whose dimension has to be deduced. */
28091 else
28093 }
28096 {
28100 /* 14.6.2.2 [temp.dep.expr]: An id-expression is type-dependent if it
28101 contains an identifier associated by name lookup with one or more
28102 declarations declared with a dependent type, or...a
28103 nested-name-specifier or qualified-id that names a member of an
28104 unknown specialization. */
28107 }
28117 {
28122 }
28124 /* A static data member of the current instantiation with incomplete
28125 array type is type-dependent, as the definition and specializations
28126 can have different bounds. */
28133 /* An array of unknown bound depending on a variadic parameter, eg:
28135 template<typename... Args>
28136 void foo (Args... args)
28137 {
28138 int arr[] = { args... };
28139 }
28141 template<int... vals>
28142 void bar ()
28143 {
28144 int arr[] = { vals... };
28145 }
28147 If the array has no length and has an initializer, it must be that
28148 we couldn't determine its length in cp_complete_array_type because
28149 it is dependent. */
28157 /* Pull a FUNCTION_DECL out of a BASELINK if we can. */
28159 {
28164 }
28166 /* A function or variable template-id is type-dependent if it has any
28167 dependent template arguments. */
28171 {
28172 /* Consider the innermost template arguments, since those are the ones
28173 that come from the template-id; the template arguments for the
28174 enclosing class do not make it type-dependent unless they are used in
28175 the type of the decl. */
28177 && (any_dependent_template_arguments_p
28180 }
28182 /* Otherwise, if the function decl isn't from a dependent scope, it can't be
28183 type-dependent. Checking this is important for functions with auto return
28184 type, which looks like a dependent type. */
28193 {
28197 }
28199 /* Otherwise, its constraints could still depend on outer template parameters
28200 from its (dependent) scope. */
28202 /* As an optimization, check this cheaper sufficient condition first.
28203 (At this point we've established that we're looking at a member of
28204 a dependent class, so it makes sense to start treating say undeduced
28205 auto as dependent.) */
28210 /* Always dependent, on the number of arguments if nothing else. */
28215 {
28220 {
28226 }
28227 /* SCOPE_REF with non-null TREE_TYPE is always non-dependent. */
28231 /* CO_AWAIT/YIELD_EXPR with unknown type is always dependent. */
28237 {
28242 }
28245 {
28252 }
28261 }
28263 /* The type of a non-type template parm declared with a placeholder type
28264 depends on the corresponding template argument, even though
28265 placeholders are not normally considered dependent. */
28272 /* Dependent type attributes might not have made it from the decl to
28273 the type yet. */
28279 }
28281 /* [temp.dep.expr]/5: A class member access expression (5.2.5) is
28282 type-dependent if the expression refers to a member of the current
28283 instantiation and the type of the referenced member is dependent, or the
28284 class member access expression refers to a member of an unknown
28285 specialization.
28287 This function returns true if the OBJECT in such a class member access
28288 expression is of an unknown specialization. */
28290 bool
28292 {
28293 /* An IDENTIFIER_NODE can sometimes have a TREE_TYPE, but it's still
28294 dependent. */
28299 }
28301 /* walk_tree callback function for instantiation_dependent_expression_p,
28302 below. Returns non-zero if a dependent subexpression is found. */
28304 static tree
28307 {
28309 {
28310 /* We don't have to worry about decltype currently because decltype
28311 of an instantiation-dependent expr is a dependent type. This
28312 might change depending on the resolution of DR 1172. */
28315 }
28318 {
28319 /* Don't treat an argument list as dependent just because it has no
28320 TREE_TYPE. */
28331 /* We'll check value-dependence separately. */
28334 /* Handle expressions with type operands. */
28339 {
28344 {
28347 else
28348 {
28351 }
28352 }
28354 }
28358 /* In a template, finish_class_member_access_expr creates a
28359 COMPONENT_REF with an IDENTIFIER_NODE for op1 even if it isn't
28360 type-dependent, so that we can check access control at
28361 instantiation time (PR 42277). See also Core issue 1273. */
28368 else
28371 /* Treat statement-expressions as dependent. */
28375 /* Treat requires-expressions as dependent. */
28386 /* Before C++17, a noexcept-specifier isn't part of the function type
28387 so it doesn't affect type dependence, but we still want to consider it
28388 for instantiation dependence. */
28397 }
28401 else
28403 }
28405 /* Returns TRUE if the EXPRESSION is instantiation-dependent, in the
28406 sense defined by the ABI:
28408 "An expression is instantiation-dependent if it is type-dependent
28409 or value-dependent, or it has a subexpression that is type-dependent
28410 or value-dependent."
28412 Except don't actually check value-dependence for unevaluated expressions,
28413 because in sizeof(i) we don't care about the value of i. Checking
28414 type-dependence will in turn check value-dependence of array bounds/template
28415 arguments as needed. */
28417 bool
28419 {
28420 tree result;
28431 }
28433 /* As above, but also check value-dependence of the expression as a whole. */
28435 bool
28437 {
28439 || (processing_template_decl
28442 }
28444 /* Like type_dependent_expression_p, but it also works while not processing
28445 a template definition, i.e. during substitution or mangling. */
28447 bool
28449 {
28455 }
28457 /* Returns TRUE if ARGS contains a type-dependent expression. */
28459 bool
28461 {
28470 }
28472 /* Returns TRUE if LIST (a TREE_LIST whose TREE_VALUEs are
28473 expressions) contains any type-dependent expressions. */
28475 bool
28477 {
28483 }
28485 /* Returns TRUE if LIST (a TREE_LIST whose TREE_VALUEs are
28486 expressions) contains any value-dependent expressions. */
28488 bool
28490 {
28496 }
28498 /* Returns TRUE if the ARG (a template argument) is dependent. */
28500 bool
28502 {
28506 /* Assume a template argument that was wrongly written by the user
28507 is dependent. This is consistent with what
28508 any_dependent_template_arguments_p [that calls this function]
28509 does. */
28519 {
28522 /* A member template of a dependent class is not necessarily
28523 type-dependent, but it is a dependent template argument because it
28524 will be a member of an unknown specialization to that template. */
28527 }
28529 {
28535 }
28538 else
28540 }
28542 /* Identify any expressions that use function parms. */
28544 static tree
28546 {
28549 {
28552 }
28554 }
28556 /* Returns true if a type specialization formed using the template
28557 arguments ARGS needs to use structural equality. */
28559 bool
28561 {
28571 {
28574 {
28580 {
28581 /* Look inside the argument pack. */
28584 }
28587 {
28596 /* An any_targ_node argument (added by add_defaults_to_ttp)
28597 makes the corresponding specialization not canonicalizable,
28598 since template_args_equal always return true for it. We
28599 may see this when called from bind_template_template_parm. */
28601 /* Checking current_function_decl because this structural
28602 comparison is only necessary for redeclaration. */
28605 && (cp_walk_tree_without_duplicates
28607 /* The identity of a class template specialization that uses
28608 a function parameter depends on the identity of the function.
28609 And if this specialization appeared in the trailing return
28610 type thereof, we don't know the identity of the function
28611 (e.g. if it's a redeclaration or a new function) until we
28612 form its signature and go through duplicate_decls. Thus
28613 it's unsafe to decide on a canonical type now (which depends
28614 on the DECL_CONTEXT of the function parameter, which can get
28615 mutated after the fact by duplicate_decls), so just require
28616 structural equality in this case (PR52830). */
28618 }
28619 }
28620 }
28623 }
28625 /* Returns true if ARGS (a collection of template arguments) contains
28626 any dependent arguments. */
28628 bool
28630 {
28637 {
28642 }
28645 }
28647 /* Returns true if ARGS contains any errors. */
28649 bool
28651 {
28659 {
28662 else
28664 }
28670 {
28675 }
28678 }
28680 /* Returns TRUE if the template TMPL is type-dependent. */
28682 bool
28684 {
28686 {
28691 }
28693 /* Template template parameters are dependent. */
28697 /* So are names that have not been looked up. */
28701 }
28703 /* Returns TRUE if the specialization TMPL<ARGS> is dependent. */
28705 bool
28707 {
28710 }
28712 /* Returns TRUE if OMP_FOR with DECLV, INITV, CONDV and INCRV vectors
28713 are dependent. */
28715 bool
28717 {
28724 {
28749 {
28753 }
28757 {
28761 {
28767 /* If this loop has a class iterator with != comparison
28768 with increment other than i++/++i/i--/--i, make sure the
28769 increment is constant. */
28772 {
28775 else
28779 }
28780 }
28781 }
28782 }
28785 }
28787 /* TYPE is a TYPENAME_TYPE. Returns the ordinary TYPE to which the
28788 TYPENAME_TYPE corresponds. Returns the original TYPENAME_TYPE if
28789 no such TYPE can be found. Note that this function peers inside
28790 uninstantiated templates and therefore should be used only in
28791 extremely limited situations. ONLY_CURRENT_P restricts this
28792 peering to the currently open classes hierarchy (which is required
28793 when comparing types). */
28795 tree
28797 {
28798 tree scope;
28799 tree name;
28800 tree decl;
28802 tree pushed_scope;
28803 tree result;
28808 /* We shouldn't have built a TYPENAME_TYPE with a non-dependent scope. */
28811 /* Usually the non-qualified identifier of a TYPENAME_TYPE is
28812 TYPE_IDENTIFIER (type). But when 'type' is a typedef variant of a
28813 TYPENAME_TYPE node, then TYPE_NAME (type) is set to the TYPE_DECL
28814 representing the typedef. In that case TYPE_IDENTIFIER (type) is
28815 not the non-qualified identifier of the TYPENAME_TYPE anymore.
28816 So by getting the TYPE_IDENTIFIER of the _main declaration_ of
28817 the TYPENAME_TYPE instead, we avoid messing up with a possible
28818 typedef variant case. */
28821 /* If the SCOPE is itself a TYPENAME_TYPE, then we need to resolve
28822 it first before we can figure out what NAME refers to. */
28824 {
28826 /* Given a class template A with a dependent base with nested type C,
28827 typedef typename A::C::C C will land us here, as trying to resolve
28828 the initial A::C leads to the local C typedef, which leads back to
28829 A::C::C. So we break the recursion now. */
28831 else
28833 }
28834 /* If we don't know what SCOPE refers to, then we cannot resolve the
28835 TYPENAME_TYPE. */
28838 /* If this is a typedef, we don't want to look inside (c++/11987). */
28841 /* If SCOPE isn't the template itself, it will not have a valid
28842 TYPE_FIELDS list. */
28844 /* scope is either the template itself or a compatible instantiation
28845 like X<T>, so look up the name in the original template. */
28847 /* If scope has no fields, it can't be a current instantiation. Check this
28848 before currently_open_class to avoid infinite recursion (71515). */
28851 /* If the SCOPE is not the current instantiation, there's no reason
28852 to look inside it. */
28855 /* Enter the SCOPE so that name lookup will be resolved as if we
28856 were in the class definition. In particular, SCOPE will no
28857 longer be considered a dependent type. */
28859 /* Look up the declaration. */
28861 tf_warning_or_error);
28865 /* For a TYPENAME_TYPE like "typename X::template Y<T>", we want to
28866 find a TEMPLATE_DECL. Otherwise, we want to find a TYPE_DECL. */
28872 {
28876 }
28879 {
28880 /* Obtain the template and the arguments. */
28883 {
28884 /* We get here with a plain identifier because a previous tentative
28885 parse of the nested-name-specifier as part of a ptr-operator saw
28886 ::template X<A>. The use of ::template is necessary in a
28887 ptr-operator, but wrong in a declarator-id.
28889 [temp.names]: In a qualified-id of a declarator-id, the keyword
28890 template shall not appear at the top level. */
28894 }
28896 /* Instantiate the template. */
28902 }
28904 /* Leave the SCOPE. */
28908 /* If we failed to resolve it, return the original typename. */
28912 /* If lookup found a typename type, resolve that too. */
28914 {
28915 /* Ill-formed programs can cause infinite recursion here, so we
28916 must catch that. */
28920 }
28922 /* Qualify the resulting type. */
28928 }
28930 /* Returns a type which represents 'auto' or 'decltype(auto)'. We use a
28931 TEMPLATE_TYPE_PARM with a level one deeper than the actual template parms,
28932 by default. If set_canonical is true, we set TYPE_CANONICAL on it. */
28934 static tree
28936 {
28952 }
28954 tree
28956 {
28958 }
28960 tree
28962 {
28964 }
28966 /* Return a C++17 deduction placeholder for class template TMPL.
28967 There are represented as an 'auto' with the special level 0 and
28968 CLASS_PLACEHOLDER_TEMPLATE set. */
28970 tree
28972 {
28975 /* Our canonical type depends on the placeholder. */
28978 }
28980 /* True iff T is a C++17 class template deduction placeholder. */
28982 bool
28984 {
28986 }
28988 /* Make a "constrained auto" type-specifier. This is an auto or
28989 decltype(auto) type with constraints that must be associated after
28990 deduction. The constraint is formed from the given concept CON
28991 and its optional sequence of template arguments ARGS.
28993 TYPE must be the result of make_auto_type or make_decltype_auto_type. */
28995 static tree
28997 {
28998 /* Build the constraint. */
29010 /* Our canonical type depends on the constraint. */
29013 /* Attach the constraint to the type declaration. */
29015 }
29017 /* Make a "constrained auto" type-specifier. */
29019 tree
29021 {
29024 }
29026 /* Make a "constrained decltype(auto)" type-specifier. */
29028 tree
29030 {
29033 }
29035 /* Returns true if the placeholder type constraint T has any dependent
29036 (explicit) template arguments. */
29038 static bool
29040 {
29045 {
29048 }
29055 }
29057 /* Build and return a concept definition. Like other templates, the
29058 CONCEPT_DECL node is wrapped by a TEMPLATE_DECL. This returns the
29059 the TEMPLATE_DECL. */
29061 tree
29063 {
29069 /* A concept-definition shall not have associated constraints. */
29071 {
29074 }
29076 /* A concept-definition shall appear in namespace scope. Templates
29077 aren't allowed in block scope, so we only need to check for class
29078 scope. */
29080 {
29083 }
29086 {
29089 }
29091 /* Initially build the concept declaration; its type is bool. */
29101 /* Push the enclosing template. */
29103 }
29105 /* Given type ARG, return std::initializer_list<ARG>. */
29107 static tree
29109 {
29114 {
29118 "deducing from brace-enclosed initializer list"
29122 }
29128 }
29130 /* Replace auto in TYPE with std::initializer_list<auto>. */
29132 static tree
29134 {
29141 }
29143 /* Hash traits for hashing possibly constrained 'auto'
29144 TEMPLATE_TYPE_PARMs for use by do_auto_deduction. */
29147 {
29150 };
29152 /* Hash the 'auto' T. */
29154 inline hashval_t
29156 {
29158 /* Matching constrained-type-specifiers denote the same template
29159 parameter, so hash the constraint. */
29161 else
29162 /* But unconstrained autos are all separate, so just hash the pointer. */
29164 }
29166 /* Compare two 'auto's. */
29170 {
29177 /* Two unconstrained autos are distinct. */
29182 }
29184 /* for_each_template_parm callback for extract_autos: if t is a (possibly
29185 constrained) auto, add it to the vector. */
29187 static int
29189 {
29192 {
29193 /* All the autos were built with index 0; fix that up now. */
29197 /* If this is a repeated constrained-type-specifier, use the index we
29198 chose before. */
29200 else
29201 {
29202 /* Otherwise this is new, so use the current count. */
29205 }
29207 {
29212 }
29213 }
29215 /* Always keep walking. */
29217 }
29219 /* Return a TREE_VEC of the 'auto's used in type under the Concepts TS, which
29220 says they can appear anywhere in the type. */
29222 static tree
29224 {
29232 {
29236 }
29239 }
29241 /* The stem for deduction guide names. */
29244 /* Return the name for a deduction guide for class template TMPL. */
29246 tree
29248 {
29259 }
29261 /* True if NAME is the name of a deduction guide. */
29263 bool
29265 {
29269 }
29271 /* True if FN is a deduction guide. */
29273 bool
29275 {
29280 }
29282 /* True if FN is the copy deduction guide, i.e. A(A)->A. */
29284 bool
29286 {
29293 }
29295 /* True if FN is a guide generated from a constructor template. */
29297 bool
29299 {
29307 }
29309 /* True if FN is an aggregate initialization guide or the copy deduction
29310 guide. */
29312 bool
29314 {
29318 /* Explicitly declared. */
29321 /* Derived from a constructor. */
29324 }
29326 /* OLDDECL is a _DECL for a template parameter. Return a similar parameter at
29327 LEVEL:INDEX, using tsubst_args and complain for substitution into non-type
29328 template parameter types. Note that the handling of template template
29329 parameters relies on current_template_parms being set appropriately for the
29330 new template. */
29332 static tree
29335 {
29341 tree newtype;
29344 {
29348 }
29349 else
29350 {
29353 {
29354 // Substitute once to fix references to other template parameters.
29357 // Now substitute again to reduce the level of the auto.
29360 }
29361 else
29364 }
29366 tree newdecl
29371 tree newidx;
29374 {
29383 {
29384 tree newresult
29389 // First create a copy (ttargs) of tsubst_args with an
29390 // additional level for the template template parameter's own
29391 // template parameters (ttparms).
29392 tree ttparms = (INNERMOST_TEMPLATE_PARMS
29400 // Substitute ttargs into ttparms to fix references to
29401 // other template parameters.
29404 // Now substitute again with args based on tparms, to reduce
29405 // the level of the ttparms.
29408 complain);
29409 // Finally, tack the adjusted parms onto tparms.
29412 // As with all template template parms, the parameter list captured
29413 // by this template template parm that corresponds to its own level
29414 // should be empty. This avoids infinite recursion when structurally
29415 // comparing two such rewritten template template parms (PR102479).
29420 // All done.
29424 }
29428 else
29430 }
29431 else
29432 {
29434 tree newconst
29446 }
29449 }
29451 /* As rewrite_template_parm, but for the whole TREE_LIST representing a
29452 template parameter. */
29454 static tree
29457 {
29472 }
29474 /* Returns a C++17 class deduction guide template based on the constructor
29475 CTOR. As a special case, CTOR can be a RECORD_TYPE for an implicit default
29476 guide, REFERENCE_TYPE for an implicit copy/move guide, or TREE_LIST for an
29477 aggregate initialization guide. OUTER_ARGS are the template arguments
29478 for the enclosing scope of the class. */
29480 static tree
29482 {
29486 location_t loc;
29490 {
29494 }
29497 {
29499 {
29503 else
29505 }
29508 else
29518 }
29519 else
29520 {
29526 fn_tmpl
29534 /* If type is a member class template, DECL_TI_ARGS (ctor) will have
29535 fully specialized args for the enclosing class. Strip those off, as
29536 the deduction guide won't have those template parameters. */
29539 /* Discard the 'this' parameter. */
29547 {
29550 /* For a member template constructor, we need to flatten the two
29551 template parameter lists into one, and then adjust the function
29552 signature accordingly. This gets...complicated. */
29555 /* For a member template we should have two levels of parms/args, one
29556 for the class and one for the constructor. We stripped
29557 specialized args for further enclosing classes above. */
29561 /* Template args for translating references to the two-level template
29562 parameters into references to the one-level template parameters we
29563 are creating. */
29568 /* Template parms for the constructor template. */
29571 /* Template parms for the class template. */
29575 /* Template parms for the deduction guide start as a copy of the
29576 template parms for the class. We set current_template_parms for
29577 lookup_template_class_1. */
29583 /* Now we need to rewrite the constructor parms to append them to the
29584 class parms. */
29586 {
29590 tree newelt
29596 }
29598 /* Now we have a final set of template parms to substitute into the
29599 function signature. */
29606 {
29608 /* FIXME: We'd like to avoid substituting outer template
29609 arguments into the constraint ahead of time, but the
29610 construction of tsubst_args assumes that outer arguments
29611 are already substituted in. */
29614 }
29616 /* Parms are to have DECL_CHAIN tsubsted, which would be skipped if
29617 cp_unevaluated_operand. */
29618 cp_evaluated ev;
29621 }
29622 else
29623 {
29624 /* Substitute in the same arguments to rewrite class members into
29625 references to members of an unknown specialization. */
29626 cp_evaluated ev;
29630 {
29632 /* FIXME: As above. */
29635 }
29636 }
29641 }
29644 {
29645 /* Copy the parms so we can set DECL_PRIMARY_TEMPLATE. */
29649 }
29653 FUNCTION_DECL,
29668 }
29670 /* Add to LIST the member types for the reshaped initializer CTOR. */
29672 static tree
29674 {
29678 {
29682 {
29688 }
29692 /* Give the trailing pack expansion parameter a default argument to
29693 match aggregate initialization behavior, even if we deduce the
29694 length of the pack separately to more than we have initializers. */
29696 /* if ei is of array type and xi is a braced-init-list or string literal,
29697 Ti is an rvalue reference to the declared type of ei */
29702 {
29704 ftype = cp_build_qualified_type
29706 ftype = (cp_build_reference_type
29708 }
29710 }
29713 }
29715 /* Return whether ETYPE is, or is derived from, a specialization of TMPL. */
29717 static bool
29719 {
29725 tree tparms = (INNERMOST_TEMPLATE_PARMS
29732 }
29736 /* Return a C++20 aggregate deduction candidate for TYPE initialized from
29737 INIT. */
29739 static tree
29741 {
29749 {
29755 }
29757 /* We might be creating a guide for a class member template, e.g.,
29759 template<typename U> struct A {
29760 template<typename T> struct B { T t; };
29761 };
29763 At this point, A will have been instantiated. Below, we need to
29764 use both A<U>::B<T> (TEMPLATE_TYPE) and A<int>::B<T> (TYPE) types. */
29765 const bool member_template_p
29769 tree template_type = (member_template_p
29775 /* No aggregate candidate for copy-initialization. */
29777 {
29781 }
29783 /* If we encounter a problem, we just won't add the candidate. */
29788 {
29793 /* If we're creating a deduction guide for a member class template,
29794 we've used the original template pattern type for the reshape_init
29795 above; this is done because we want PARMS to be a template parameter
29796 type, something that can be deduced when used as a function template
29797 parameter. At this point the outer class template has already been
29798 partially instantiated (we deferred the deduction until the enclosing
29799 scope is non-dependent). Therefore we have to partially instantiate
29800 PARMS, so that its template level is properly reduced and we don't get
29801 mismatches when deducing types using the guide with PARMS. */
29803 {
29807 }
29808 }
29810 {
29813 len;
29815 {
29821 }
29822 }
29823 else
29824 /* Aggregate initialization doesn't apply to an initializer expression. */
29828 {
29834 }
29837 }
29839 /* UGUIDES are the deduction guides for the underlying template of alias
29840 template TMPL; adjust them to be deduction guides for TMPL. */
29842 static tree
29844 {
29845 /* [over.match.class.deduct]: When resolving a placeholder for a deduced
29846 class type (9.2.8.2) where the template-name names an alias template A,
29847 the defining-type-id of A must be of the form
29849 typename(opt) nested-name-specifier(opt) template(opt) simple-template-id
29851 as specified in 9.2.8.2. The guides of A are the set of functions or
29852 function templates formed as follows. For each function or function
29853 template f in the guides of the template named by the simple-template-id
29854 of the defining-type-id, the template arguments of the return type of f
29855 are deduced from the defining-type-id of A according to the process in
29856 13.10.2.5 with the exception that deduction does not fail if not all
29857 template arguments are deduced. Let g denote the result of substituting
29858 these deductions into f. If substitution succeeds, form a function or
29859 function template f' with the following properties and add it to the set
29860 of guides of A:
29862 * The function type of f' is the function type of g.
29864 * If f is a function template, f' is a function template whose template
29865 parameter list consists of all the template parameters of A (including
29866 their default template arguments) that appear in the above deductions or
29867 (recursively) in their default template arguments, followed by the
29868 template parameters of f that were not deduced (including their default
29869 template arguments), otherwise f' is not a function template.
29871 * The associated constraints (13.5.2) are the conjunction of the
29872 associated constraints of g and a constraint that is satisfied if and only
29873 if the arguments of A are deducible (see below) from the return type.
29875 * If f is a copy deduction candidate (12.4.1.8), then f' is considered to
29876 be so as well.
29878 * If f was generated from a deduction-guide (12.4.1.8), then f' is
29879 considered to be so as well.
29881 * The explicit-specifier of f' is the explicit-specifier of g (if
29882 any). */
29892 {
29899 {
29903 /* Deduce template arguments for f from the type-id of A. */
29909 /* CWG2664: Discard any deductions, still build the guide. */
29913 /* The number of parms for f' is the number of parms of A used in
29914 the deduced arguments plus non-deduced parms of f. */
29926 /* Set current_template_parms as in build_deduction_guide. */
29934 /* First copy over the used parms of A. */
29937 {
29940 {
29945 }
29946 }
29949 /* Adjust the deduced template args for f to refer to the A parms
29950 with their new indexes. */
29954 /* Now rewrite the non-deduced parms of f. */
29957 {
29964 }
29967 /* Substitute the deduced arguments plus the rewritten template
29968 parameters into f to get g. This covers the type, copyness,
29969 guideness, and explicit-specifier. */
29970 tree g;
29971 {
29972 /* Parms are to have DECL_CHAIN tsubsted, which would be skipped
29973 if cp_unevaluated_operand. */
29974 cp_evaluated ev;
29976 }
29980 {
29981 /* The targs are all non-dependent, so g isn't a template. */
29985 }
29994 /* Substitute the associated constraints. */
30001 /* Add a constraint that the return type matches the instantiation of
30002 A with the same template arguments. */
30005 /* FIXME this should mean they don't compare as equivalent. */
30007 {
30010 }
30013 {
30016 }
30017 }
30018 else
30019 {
30020 /* For a non-template deduction guide, if the arguments of A aren't
30021 deducible from the return type, don't add the candidate. */
30022 non_template:
30025 }
30028 }
30031 }
30033 /* True iff template arguments for TMPL can be deduced from TYPE.
30034 Used to implement CPTK_IS_DEDUCIBLE for alias CTAD according to
30035 [over.match.class.deduct].
30037 This check is specified in terms of partial specialization, so the behavior
30038 should be parallel to that of get_partial_spec_bindings. */
30040 bool
30042 {
30048 /* If tmpl is a class template, this is trivial: it's deducible if TYPE is a
30049 specialization of TMPL. */
30055 /* Otherwise it's an alias template. */
30056 again:
30061 /* We don't fail on an undeduced targ the second time through (like
30062 get_partial_spec_bindings) because we're going to try defaults. */
30065 {
30071 {
30076 }
30077 /* If the type parameter is a parameter pack, then it will be deduced
30078 to an empty parameter pack. This is another case that doesn't model
30079 well as partial specialization. */
30081 {
30082 tree arg;
30084 {
30087 }
30088 else
30092 }
30093 }
30095 /* Maybe add in default template args. This seems like a flaw in the
30096 specification in terms of partial specialization, since it says the
30097 partial specialization has the the template parameter list of A, but a
30098 partial specialization can't have default targs. */
30103 /* I believe we don't need the template_template_parm_bindings_ok_p call
30104 because coerce_template_parms did coerce_template_template_parms. */
30107 }
30109 /* Return artificial deduction guides built from the constructors of class
30110 template TMPL. */
30112 static tree
30114 {
30121 {
30122 /* Skip inherited constructors. */
30128 }
30130 /* Add implicit default constructor deduction guide. */
30132 {
30134 complain);
30136 }
30138 /* Add copy guide. */
30139 {
30142 complain);
30144 }
30147 }
30151 /* Return the non-aggregate deduction guides for deducible template TMPL. The
30152 aggregate candidate is added separately because it depends on the
30153 initializer. Set ANY_DGUIDES_P if we find a non-implicit deduction
30154 guide. */
30156 static tree
30158 {
30161 {
30165 complain);
30166 }
30167 else
30168 {
30174 else
30176 }
30178 /* Cache the deduction guides for a template. We also remember the result of
30179 lookup, and rebuild everything if it changes; should be very rare. */
30183 {
30187 }
30188 else
30189 {
30192 }
30197 else
30198 {
30202 }
30206 }
30208 /* Return whether TMPL is a (class template argument-) deducible template. */
30210 bool
30212 {
30213 /* A deducible template is either a class template or is an alias template
30214 whose defining-type-id is of the form
30216 typename(opt) nested-name-specifier(opt) template(opt) simple-template-id
30218 where the nested-name-specifier (if any) is non-dependent and the
30219 template-name of the simple-template-id names a deducible template. */
30230 }
30232 /* Deduce template arguments for the class template placeholder PTYPE for
30233 template TMPL based on the initializer INIT, and return the resulting
30234 type. */
30236 static tree
30239 {
30240 /* We should have handled this in the caller. */
30244 /* If the class was erroneous, don't try to deduce, because that
30245 can generate a lot of diagnostic. */
30251 /* Wait until the enclosing scope is non-dependent. */
30256 /* Initializing one placeholder from another. */
30267 {
30271 }
30273 {
30275 {
30276 /* Be permissive with equivalent alias templates. */
30279 bool complained
30281 "alias template deduction only available "
30286 {
30289 }
30290 }
30291 else
30293 }
30295 /* Wait until the initializer is non-dependent. */
30299 /* Don't bother with the alias rules for an equivalent template. */
30312 {
30317 {
30318 /* As an exception, the first phase in 16.3.1.7 (considering the
30319 initializer list as a single argument) is omitted if the
30320 initializer list consists of a single expression of type cv U,
30321 where U is a specialization of C or a class derived from a
30322 specialization of C. */
30326 }
30329 else
30331 }
30334 else
30337 /* Do this now to avoid problems with erroneous args later on. */
30347 /* Prune explicit deduction guides in copy-initialization context (but
30348 not copy-list-initialization). */
30351 {
30357 {
30358 /* Found a nonconverting guide, prune the candidates. */
30365 }
30366 }
30374 /* If this is list-initialization and the class has a list guide, first
30375 try deducing from the list as a single argument, as [over.match.list]. */
30377 {
30385 {
30386 /* That didn't work, now try treating the list as a sequence of
30387 arguments. */
30393 }
30394 }
30397 {
30399 " of %qT, as it has no non-explicit deduction guides or "
30402 }
30404 {
30408 }
30414 {
30416 {
30422 }
30424 }
30425 /* [over.match.list]/1: In copy-list-initialization, if an explicit
30426 constructor is chosen, the initialization is ill-formed. */
30428 {
30430 {
30432 {
30433 // TODO: Pass down location from cp_finish_decl.
30435 "explicit deduction guide selected in "
30440 }
30442 }
30443 }
30445 /* If CTAD succeeded but the type doesn't have any explicit deduction
30446 guides, this deduction might not be what the user intended. */
30448 {
30452 "%qT may not intend to support class template argument "
30456 }
30460 }
30462 /* Return true if INIT is an unparenthesized id-expression or an
30463 unparenthesized class member access. Used for the argument of
30464 decltype(auto). */
30466 bool
30468 {
30471 /* We need to be able to tell '(r)' and 'r' apart (when it's of
30472 reference type). Only the latter is an id-expression. */
30480 }
30482 /* Replace occurrences of 'auto' in TYPE with the appropriate type deduced
30483 from INIT. AUTO_NODE is the TEMPLATE_TYPE_PARM used for 'auto' in TYPE.
30484 The CONTEXT determines the context in which auto deduction is performed
30485 and is used to control error diagnostics. FLAGS are the LOOKUP_* flags.
30487 OUTER_TARGS is used during template argument deduction (context == adc_unify)
30488 to properly substitute the result. It's also used in the adc_unify and
30489 adc_requirement contexts to communicate the necessary template arguments
30490 to satisfaction. OUTER_TARGS is ignored in other contexts.
30492 Additionally for adc_unify contexts TMPL is the template for which TYPE
30493 is a template parameter type.
30495 For partial-concept-ids, extra args from OUTER_TARGS, TMPL and the current
30496 scope may be appended to the list of deduced template arguments prior to
30497 determining constraint satisfaction as appropriate. */
30499 tree
30506 {
30512 /* Defining a subset of type-dependent expressions that we can deduce
30513 from ahead of time isn't worth the trouble. */
30516 /* Similarly, we can't deduce from another undeduced decl. */
30520 /* We may be doing a partial substitution, but we still want to replace
30521 auto_node. */
30525 {
30526 /* We don't recurse here because we can't deduce from a nested
30527 initializer_list. */
30531 }
30535 /* In C++23, we must deduce the type to int&& for code like
30536 decltype(auto) f(int&& x) { return (x); }
30537 or
30538 auto&& f(int x) { return x; }
30539 so we use treat_lvalue_as_rvalue_p. But don't do it for
30540 decltype(auto) f(int x) { return x; }
30541 where we should deduce 'int' rather than 'int&&'; transmogrifying
30542 INIT to an rvalue would break that. */
30543 tree r;
30553 /* C++17 class template argument deduction. */
30557 /* Nothing we can do with this, even in deduction context. */
30562 /* [dcl.spec.auto]: Obtain P from T by replacing the occurrences of auto
30563 with either a new invented type template parameter U or, if the
30564 initializer is a braced-init-list (8.5.4), with
30565 std::initializer_list<U>. */
30567 {
30572 else
30573 {
30575 {
30579 "for deduction to %<std::initializer_list%>, use copy-"
30581 }
30583 }
30584 }
30589 tree targs;
30593 {
30594 /* [dcl.struct.bind]/1 - if decomposition declaration has no ref-qualifiers
30595 and initializer has array type, deduce cv-qualified array type. */
30598 }
30600 {
30608 }
30609 else
30610 {
30615 tree tparms;
30619 else
30620 {
30624 }
30628 DEDUCE_CALL,
30631 {
30633 /* Try again at instantiation time. */
30637 /* If type is error_mark_node a diagnostic must have been
30638 emitted by now. Also, having a mention to '<type error>'
30639 in the diagnostic is not really useful to the user. */
30640 {
30643 && (auto_node
30647 init);
30648 else
30651 DEDUCE_CALL,
30653 }
30655 }
30656 }
30658 /* Check any placeholder constraints against the deduced type. */
30662 {
30664 {
30669 /* If the constraint is dependent, we need to wait until
30670 instantiation time to resolve the placeholder. */
30673 }
30680 {
30684 {
30685 /* As in satisfy_declaration_constraints. */
30689 else
30691 }
30692 }
30699 /* HACK: Compensate for callers not always communicating all levels of
30700 outer template arguments by filling in the outermost missing levels
30701 with dummy levels before checking satisfaction. We'll still crash
30702 if the constraint depends on a template argument belonging to one of
30703 these missing levels, but this hack otherwise allows us to handle a
30704 large subset of possible constraints (including all non-dependent
30705 constraints). */
30708 {
30713 }
30716 {
30718 {
30719 auto_diagnostic_group d;
30721 {
30739 }
30741 }
30743 }
30744 }
30747 /* The outer template arguments are already substituted into type
30754 }
30756 /* Substitutes LATE_RETURN_TYPE for 'auto' in TYPE and returns the
30757 result. */
30759 tree
30761 {
30763 {
30766 }
30770 {
30771 /* In an abbreviated function template we didn't know we were dealing
30772 with a function template when we saw the auto return type, so rebuild
30773 the return type using an auto with the correct level. */
30778 auto_vec);
30779 /* Also rebuild the constraint info in terms of the new auto. */
30787 }
30789 }
30791 /* Returns true iff TYPE is a TEMPLATE_TYPE_PARM representing 'auto' or
30792 'decltype(auto)' or a deduced class template. */
30794 bool
30796 {
30801 else
30803 }
30805 /* for_each_template_parm callback for type_uses_auto. */
30807 int
30809 {
30811 }
30813 /* Returns the TEMPLATE_TYPE_PARM in TYPE representing `auto' iff TYPE contains
30814 a use of `auto'. Returns NULL_TREE otherwise. */
30816 tree
30818 {
30822 /* For parameter packs, check the contents of the pack. */
30827 {
30828 /* The Concepts TS allows multiple autos in one type-specifier; just
30829 return the first one we find, do_auto_deduction will collect all of
30830 them. */
30834 else
30836 }
30837 else
30839 }
30841 /* Report ill-formed occurrences of auto types in ARGUMENTS. If
30842 concepts are enabled, auto is acceptable in template arguments, but
30843 only when TEMPL identifies a template class. Return TRUE if any
30844 such errors were reported. */
30846 bool
30848 {
30850 /* Only the concepts TS allows 'auto' as a type-id; it'd otherwise
30851 have already been rejected by the parser more generally. */
30854 /* If there were previous errors, nevermind. */
30858 /* If TMPL is an identifier, we're parsing and we can't tell yet
30859 whether TMPL is supposed to be a type, a function or a variable.
30860 We'll only be able to tell during template substitution, so we
30861 expect to be called again then. If concepts are enabled and we
30862 know we have a type, we're ok. */
30869 /* Quickly search for any occurrences of auto; usually there won't
30870 be any, and then we'll avoid allocating the vector. */
30878 {
30883 }
30886 }
30888 /* Recursively walk over && expressions searching for EXPR. Return a reference
30889 to that expression. */
30892 {
30896 {
30901 }
30903 }
30905 /* Convert the generic type parameters in PARM that match the types given in the
30906 range [START_IDX, END_IDX) from the current_template_parms into generic type
30907 packs. */
30909 tree
30911 {
30922 {
30923 /* Create a distinct parameter pack type from the current parm and add it
30924 to the replacement args to tsubst below into the generic function
30925 parameter. */
30939 /* Replace the current template parameter with new pack. */
30942 /* Surgically adjust the associated constraint of adjusted parameter
30943 and it's corresponding contribution to the current template
30944 requirements. */
30946 {
30951 TRUTH_ANDIF_EXPR);
30954 /* If there was a constraint, we also need to replace that in
30955 the template requirements, which we've already built. */
30959 }
30960 }
30966 /* If there are more levels then build up the replacement with the outer
30967 template parms. */
30971 replacement);
30974 }
30976 /* __integer_pack(N) in a pack expansion expands to a sequence of numbers from
30977 0..N-1. */
30979 void
30981 {
30984 integer_type_node,
30985 NULL_TREE),
30989 CP_BUILT_IN_INTEGER_PACK);
30990 }
30992 /* Walk the decl or type specialization table calling FN on each
30993 entry. */
30995 void
30999 {
31005 }
31007 /* Lookup the specialization of *ELT, in the decl or type
31008 specialization table. Return the SPEC that's already there, or
31009 NULL if nothing. */
31011 tree
31013 {
31023 }
31025 /* Return flags encoding whether SPEC is on the instantiation and/or
31026 specialization lists of TMPL. */
31028 unsigned
31030 {
31036 {
31039 }
31044 /* Only need to search if DECL is a partial specialization. */
31048 {
31051 }
31054 }
31056 /* Add a new specialization described by SPEC. DECL is the
31057 maybe-template decl and FLAGS is as returned from
31058 get_mergeable_specialization_flags. */
31060 void
31063 {
31066 {
31075 {
31078 }
31079 }
31082 {
31085 /* We don't distinguish different constrained partial type
31086 specializations, so there could be duplicates. Everything else
31087 must be new. */
31089 {
31095 }
31096 }
31103 {
31104 /* A partial specialization. */
31109 }
31110 }
31112 /* Set up the hash tables for template instantiations. */
31114 void
31116 {
31122 }
31124 /* Print stats about the template hash tables for -fstats. */
31126 void
31128 {
31137 }
31139 #if CHECKING_P
31143 /* Verify that type_dependent_expression_p () works correctly, even
31144 in the presence of location wrapper nodes. */
31146 static void
31148 {
31153 /* If no templates are involved, nothing is type-dependent. */
31159 /* Within a template, an unresolved name is always type-dependent. */
31162 /* Ensure it copes with NULL_TREE and errors. */
31166 /* A USING_DECL in a template should be type-dependent, even if wrapped
31167 with a location wrapper (PR c++/83799). */
31176 }
31178 /* Run all of the selftests within this file. */
31180 void
31182 {
31184 }