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1 /* Functions related to invoking -*- C++ -*- methods and overloaded functions.
2 Copyright (C) 1987-2023 Free Software Foundation, Inc.
3 Contributed by Michael Tiemann (tiemann@cygnus.com) and
4 modified by Brendan Kehoe (brendan@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/>. */
23 /* High-level class interface. */
47 /* The various kinds of conversion. */
50 ck_identity,
51 ck_lvalue,
52 ck_fnptr,
53 ck_qual,
54 ck_std,
55 ck_ptr,
56 ck_pmem,
57 ck_base,
58 ck_ref_bind,
59 ck_user,
60 ck_ambig,
61 ck_list,
62 ck_aggr,
63 ck_rvalue,
64 /* When LOOKUP_SHORTCUT_BAD_CONVS is set, we may return a conversion of
65 this kind whenever we know the true conversion is either bad or outright
66 invalid, but we don't want to attempt to compute the bad conversion (for
67 sake of avoiding unnecessary instantiation). bad_p should always be set
68 for these. */
69 ck_deferred_bad,
70 };
72 /* The rank of the conversion. Order of the enumerals matters; better
73 conversions should come earlier in the list. */
76 cr_identity,
77 cr_exact,
78 cr_promotion,
79 cr_std,
80 cr_pbool,
81 cr_user,
82 cr_ellipsis,
83 cr_bad
84 };
86 /* An implicit conversion sequence, in the sense of [over.best.ics].
87 The first conversion to be performed is at the end of the chain.
88 That conversion is always a cr_identity conversion. */
91 /* The kind of conversion represented by this step. */
92 conversion_kind kind;
93 /* The rank of this conversion. */
94 conversion_rank rank;
98 /* True if this conversion would be permitted with a bending of
99 language standards, e.g. disregarding pointer qualifiers or
100 converting integers to pointers. */
102 /* If KIND is ck_ref_bind or ck_base, true to indicate that a
103 temporary should be created to hold the result of the
104 conversion. If KIND is ck_ambig or ck_user, true means force
105 copy-initialization. */
107 /* If KIND is ck_ptr or ck_pmem, true to indicate that a conversion
108 from a pointer-to-derived to pointer-to-base is being performed. */
110 /* If KIND is ck_ref_bind, true when either an lvalue reference is
111 being bound to an lvalue expression or an rvalue reference is
112 being bound to an rvalue expression. If KIND is ck_rvalue or ck_base,
113 true when we are treating an lvalue as an rvalue (12.8p33). If
114 ck_identity, we will be binding a reference directly or decaying to
115 a pointer. */
118 /* Whether check_narrowing should only check TREE_CONSTANTs; used
119 in build_converted_constant_expr. */
121 /* True if this conversion is taking place in a copy-initialization context
122 and we should only consider converting constructors. Only set in
123 ck_base and ck_rvalue. */
125 /* The type of the expression resulting from the conversion. */
126 tree type;
128 /* The next conversion in the chain. Since the conversions are
129 arranged from outermost to innermost, the NEXT conversion will
130 actually be performed before this conversion. This variant is
131 used only when KIND is neither ck_identity, ck_aggr, ck_ambig nor
132 ck_list. Please use the next_conversion function instead
133 of using this field directly. */
135 /* The expression at the beginning of the conversion chain. This
136 variant is used only if KIND is ck_identity, ck_aggr, or ck_ambig.
137 You can use conv_get_original_expr to get this expression. */
138 tree expr;
139 /* The array of conversions for an initializer_list, so this
140 variant is used only when KIN D is ck_list. */
143 /* The function candidate corresponding to this conversion
144 sequence. This field is only used if KIND is ck_user. */
146 };
148 #define CONVERSION_RANK(NODE) \
149 ((NODE)->bad_p ? cr_bad \
150 : (NODE)->ellipsis_p ? cr_ellipsis \
151 : (NODE)->user_conv_p ? cr_user \
152 : (NODE)->rank)
154 #define BAD_CONVERSION_RANK(NODE) \
155 ((NODE)->ellipsis_p ? cr_ellipsis \
156 : (NODE)->user_conv_p ? cr_user \
157 : (NODE)->rank)
166 tsubst_flags_t);
173 tsubst_flags_t);
177 tsubst_flags_t);
197 tsubst_flags_t);
199 tsubst_flags_t);
218 tsubst_flags_t);
226 /* Returns nonzero iff the destructor name specified in NAME matches BASETYPE.
227 NAME can take many forms... */
229 bool
231 {
232 /* Just accept something we've already complained about. */
241 {
247 /* Otherwise lookup the name, it could be an unrelated typedef
248 of the correct type. */
255 }
256 else
257 {
258 /* In the case of:
260 template <class T> struct S { ~S(); };
261 int i;
262 i.~S();
264 NAME will be a class template. */
267 }
270 }
272 /* We want the address of a function or method. We avoid creating a
273 pointer-to-member function. */
275 tree
277 {
280 /* We have to do these by hand to avoid real pointer to member
281 functions. */
283 {
285 {
289 complain);
290 }
292 }
296 else
300 }
302 /* Build a CALL_EXPR, we can handle FUNCTION_TYPEs, METHOD_TYPEs, or
303 POINTER_TYPE to those. Note, pointer to member function types
304 (TYPE_PTRMEMFUNC_P) must be handled by our callers. There are
305 two variants. build_call_a is the primitive taking an array of
306 arguments, while build_call_n is a wrapper that handles varargs. */
308 tree
310 {
313 else
314 {
324 }
325 }
327 /* Update various flags in cfun and the call itself based on what is being
328 called. Split out of build_call_a so that bot_manip can use it too. */
330 void
332 {
333 /* Handle both CALL_EXPRs and AGGR_INIT_EXPRs. */
336 /* We check both the decl and the type; a function may be known not to
337 throw without being declared throw(). */
347 {
353 }
356 }
358 tree
360 {
361 tree decl;
362 tree result_type;
363 tree fntype;
372 /* An rvalue has no cv-qualifiers. */
383 {
384 /* We invoke build_call directly for several library
385 functions. These may have been declared normally if
386 we're building libgcc, so we can't just check
387 DECL_ARTIFICIAL. */
392 }
398 /* Don't pass empty class objects by value. This is useful
399 for tags in STL, which are used to control overload resolution.
400 We don't need to handle other cases of copying empty classes. */
403 {
407 {
409 /* We're disconnecting the initializer from its target,
410 don't create a temporary. */
415 }
416 }
419 }
421 /* New overloading code. */
428 };
430 /* Information for providing diagnostics about why overloading failed. */
433 rr_none,
434 rr_arity,
435 rr_explicit_conversion,
436 rr_template_conversion,
437 rr_arg_conversion,
438 rr_bad_arg_conversion,
439 rr_template_unification,
440 rr_invalid_copy,
441 rr_inherited_ctor,
442 rr_constraint_failure
443 };
446 /* The index of the argument, 0-based. */
448 /* The actual argument or its type. */
449 tree from;
450 /* The type of the parameter. */
451 tree to_type;
452 /* The location of the argument. */
453 location_t loc;
454 };
459 /* Information about an arity mismatch. */
461 /* The expected number of arguments. */
463 /* The actual number of arguments in the call. */
465 /* Whether EXPECTED should be treated as a lower bound. */
468 /* Information about an argument conversion mismatch. */
470 /* Same, but for bad argument conversions. */
472 /* Information about template unification failures. These are the
473 parameters passed to fn_type_unification. */
475 tree tmpl;
476 tree explicit_targs;
480 tree return_type;
481 unification_kind_t strict;
484 /* Information about template instantiation failures. These are the
485 parameters passed to instantiate_template. */
487 tree tmpl;
488 tree targs;
491 };
494 /* The FUNCTION_DECL that will be called if this candidate is
495 selected by overload resolution. */
496 tree fn;
497 /* If not NULL_TREE, the first argument to use when calling this
498 function. */
499 tree first_arg;
500 /* The rest of the arguments to use when calling this function. If
501 there are no further arguments this may be NULL or it may be an
502 empty vector. */
504 /* The implicit conversion sequences for each of the arguments to
505 FN. */
507 /* The number of implicit conversion sequences. */
509 /* If FN is a user-defined conversion, the standard conversion
510 sequence from the type returned by FN to the desired destination
511 type. */
514 /* If FN is a member function, the binfo indicating the path used to
515 qualify the name of FN at the call site. This path is used to
516 determine whether or not FN is accessible if it is selected by
517 overload resolution. The DECL_CONTEXT of FN will always be a
518 (possibly improper) base of this binfo. */
519 tree access_path;
520 /* If FN is a non-static member function, the binfo indicating the
521 subobject to which the `this' pointer should be converted if FN
522 is selected by overload resolution. The type pointed to by
523 the `this' pointer must correspond to the most derived class
524 indicated by the CONVERSION_PATH. */
525 tree conversion_path;
526 tree template_decl;
527 tree explicit_targs;
532 /* The flags active in add_candidate. */
537 };
539 /* Returns true iff T is a null pointer constant in the sense of
540 [conv.ptr]. */
542 bool
544 {
547 /* [conv.ptr]
549 A null pointer constant is an integer literal ([lex.icon]) with value
550 zero or a prvalue of type std::nullptr_t. */
555 {
558 /* Core issue 903 says only literal 0 is a null pointer constant. */
565 }
567 {
572 }
575 }
577 /* Returns true iff T is a null member pointer value (4.11). */
579 bool
581 {
591 else
593 }
595 /* Returns nonzero if PARMLIST consists of only default parms,
596 ellipsis, and/or undeduced parameter packs. */
598 bool
600 {
607 }
609 /* Allocate N bytes of memory from the conversion obstack. The memory
610 is zeroed before being returned. */
614 {
617 {
620 }
624 }
626 /* RAII class to discard anything added to conversion_obstack. */
628 struct conversion_obstack_sentinel
629 {
633 };
635 /* Allocate rejection reasons. */
639 {
644 }
648 {
655 }
659 location_t loc)
660 {
668 }
672 location_t loc)
673 {
681 }
685 {
692 }
696 {
703 }
710 {
717 /* Copy args to our own storage. */
725 }
729 {
731 }
735 {
738 }
742 {
745 }
747 /* Build a constraint failure record. */
751 {
754 }
756 /* Dynamically allocate a conversion. */
760 {
765 }
767 /* Make sure that all memory on the conversion obstack has been
768 freed. */
770 void
772 {
776 }
778 /* Dynamically allocate an array of N conversions. */
782 {
784 }
786 /* True iff the active member of conversion::u for code CODE is NEXT. */
790 {
796 }
800 {
804 /* Only call this function for conversions that use u.next. */
807 /* Note that the caller is responsible for filling in t->cand for
808 user-defined conversions. */
814 {
831 }
837 }
839 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
840 specialization of std::initializer_list<T>, if such a conversion is
841 possible. */
845 {
851 tree val;
853 /* Within a list-initialization we can have more user-defined
854 conversions. */
856 /* But no narrowing conversions. */
859 /* Can't make an array of these types. */
866 {
867 conversion *sub
874 }
882 {
890 }
893 }
895 /* Return the next conversion of the conversion chain (if applicable),
896 or NULL otherwise. Please use this function instead of directly
897 accessing fields of struct conversion. */
901 {
906 }
908 /* Strip to the first ck_user, ck_ambig, ck_list, ck_aggr or ck_identity
909 encountered. */
913 {
919 }
921 /* Subroutine of build_aggr_conv: check whether FROM is a valid aggregate
922 initializer for array type ATYPE. */
924 static bool
926 {
931 {
933 {
938 else
940 complain);
943 }
945 }
951 /* No other valid way to aggregate initialize an array. */
953 }
955 /* Helper for build_aggr_conv. Return true if FIELD is in PSET, or if
956 FIELD has ANON_AGGR_TYPE_P and any initializable field in there recursively
957 is in PSET. */
959 static bool
961 {
967 {
973 }
975 }
977 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
978 aggregate class, if such a conversion is possible. */
982 {
989 /* We already called reshape_init in implicit_conversion, but it might not
990 have done anything in the case of parenthesized aggr init. */
992 /* The conversions within the init-list aren't affected by the enclosing
993 context; they're always simple copy-initialization. */
996 /* For designated initializers, verify that each initializer is convertible
997 to corresponding TREE_TYPE (ce->index) and mark those FIELD_DECLs as
998 visited. In the following loop then ignore already visited
999 FIELD_DECLs. */
1002 {
1013 else
1015 complain);
1020 /* For unions, there should be just one initializer. */
1022 {
1026 }
1028 }
1031 {
1038 {
1043 }
1047 /* Value-initialization of reference is ill-formed. */
1049 else
1050 {
1054 }
1058 else
1060 complain);
1067 }
1079 }
1081 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
1082 array type, if such a conversion is possible. */
1086 {
1094 /* We might need to propagate the size from the element to the array. */
1099 {
1103 }
1108 {
1109 conversion *sub
1121 }
1130 }
1132 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
1133 complex type, if such a conversion is possible. */
1137 tsubst_flags_t complain)
1138 {
1152 {
1153 conversion *sub
1165 }
1174 }
1176 /* Build a representation of the identity conversion from EXPR to
1177 itself. The TYPE should match the type of EXPR, if EXPR is non-NULL. */
1181 {
1189 }
1191 /* Converting from EXPR to TYPE was ambiguous in the sense that there
1192 were multiple user-defined conversions to accomplish the job.
1193 Build a conversion that indicates that ambiguity. */
1197 {
1205 }
1207 tree
1209 {
1213 }
1215 /* Returns the standard conversion path (see [conv]) from type FROM to type
1216 TO, if any. For proper handling of null pointer constants, you must
1217 also pass the expression EXPR to convert from. If C_CAST_P is true,
1218 this conversion is coming from a C-style cast. */
1223 {
1227 tree qualified_to;
1231 {
1234 }
1240 {
1242 {
1248 }
1250 {
1251 /* Necessary for eg, TEMPLATE_ID_EXPRs (c++/50961). */
1254 }
1255 }
1262 {
1265 /* Tell convert_like that we're using the address. */
1268 }
1269 /* Wrapping a ck_rvalue around a class prvalue (as a result of using
1270 obvalue_p) seems odd, since it's already a prvalue, but that's how we
1271 express the copy constructor call required by copy-initialization. */
1273 {
1275 {
1276 tree bitfield_type;
1279 {
1282 }
1283 }
1285 /* If we're performing copy-initialization, remember to skip
1286 explicit constructors. */
1289 }
1291 /* Allow conversion between `__complex__' data types. */
1293 {
1294 /* The standard conversion sequence to convert FROM to TO is
1295 the standard conversion sequence to perform componentwise
1296 conversion. */
1299 complain);
1305 else
1306 {
1309 }
1312 }
1315 {
1319 }
1321 /* [conv.ptr]
1322 A null pointer constant can be converted to a pointer type; ... A
1323 null pointer constant of integral type can be converted to an
1324 rvalue of type std::nullptr_t. */
1332 {
1333 /* For backwards brain damage compatibility, allow interconversion of
1334 pointers and integers with a pedwarn. */
1337 }
1339 {
1340 /* For backwards brain damage compatibility, allow interconversion of
1341 enums and integers with a pedwarn. */
1344 }
1347 {
1348 tree to_pointee;
1349 tree from_pointee;
1352 {
1356 /* Since this is the target of a pointer, it can't have function
1357 qualifiers, so any TYPE_QUALS must be for attributes const or
1358 noreturn. Strip them. */
1365 }
1366 else
1367 {
1370 }
1374 to_pointee))
1375 ;
1379 {
1381 /* Don't try to apply restrict to void. */
1386 }
1388 {
1395 && (same_type_ignoring_top_level_qualifiers_p
1397 {
1400 }
1401 else
1403 }
1406 /* [conv.ptr]
1408 An rvalue of type "pointer to cv D," where D is a
1409 class type, can be converted to an rvalue of type
1410 "pointer to cv B," where B is a base class (clause
1411 _class.derived_) of D. If B is an inaccessible
1412 (clause _class.access_) or ambiguous
1413 (_class.member.lookup_) base class of D, a program
1414 that necessitates this conversion is ill-formed.
1415 Therefore, we use DERIVED_FROM_P, and do not check
1416 access or uniqueness. */
1418 {
1419 from_pointee
1425 }
1430 /* In a C-style cast, we ignore CV-qualification because we
1431 are allowed to perform a static_cast followed by a
1432 const_cast. */
1437 /* converting from string constant to char *. */
1441 /* Allow conversions among compatible ObjC pointer types (base
1442 conversions have been already handled above). */
1447 {
1450 }
1451 else
1455 }
1457 {
1463 /* If FBASE and TBASE are equivalent but incomplete, DERIVED_FROM_P
1464 yields false. But a pointer to member of incomplete class is OK. */
1473 else
1477 {
1479 tbase,
1485 }
1488 }
1490 {
1491 /* [conv.bool]
1493 A prvalue of arithmetic, unscoped enumeration, pointer, or pointer
1494 to member type can be converted to a prvalue of type bool. ...
1495 For direct-initialization (8.5 [dcl.init]), a prvalue of type
1496 std::nullptr_t can be converted to a prvalue of type bool; */
1502 {
1515 }
1518 }
1519 /* We don't check for ENUMERAL_TYPE here because there are no standard
1520 conversions to enum type. */
1521 /* As an extension, allow conversion to complex type. */
1523 {
1529 /* If we're parsing an enum with no fixed underlying type, we're
1530 dealing with an incomplete type, which renders the conversion
1531 ill-formed. */
1542 /* Give this a better rank if it's a promotion.
1544 To handle CWG 1601, also bump the rank if we are converting
1545 an enumeration with a fixed underlying type to the underlying
1546 type. */
1552 /* A prvalue of floating-point type can be converted to a prvalue of
1553 another floating-point type with a greater or equal conversion
1554 rank ([conv.rank]). A prvalue of standard floating-point type can
1555 be converted to a prvalue of another standard floating-point type.
1556 For backwards compatibility with handling __float128 and other
1557 non-standard floating point types, allow all implicit floating
1558 point conversions if neither type is extended floating-point
1559 type and if at least one of them is, fail if they have unordered
1560 conversion rank or from has higher conversion rank. */
1567 }
1573 {
1577 /* The derived-to-base conversion indicates the initialization
1578 of a parameter with base type from an object of a derived
1579 type. A temporary object is created to hold the result of
1580 the conversion unless we're binding directly to a reference. */
1582 /* If we're performing copy-initialization, remember to skip
1583 explicit constructors. */
1586 }
1587 else
1594 }
1596 /* Returns nonzero if T1 is reference-related to T2. */
1598 bool
1600 {
1607 /* [dcl.init.ref]
1609 Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
1610 to "cv2 T2" if T1 is similar to T2, or T1 is a base class of T2. */
1614 }
1616 /* Returns nonzero if T1 is reference-compatible with T2. */
1618 bool
1620 {
1621 /* [dcl.init.ref]
1623 "cv1 T1" is reference compatible with "cv2 T2" if
1624 a prvalue of type "pointer to cv2 T2" can be converted to the type
1625 "pointer to cv1 T1" via a standard conversion sequence. */
1633 }
1635 /* Return true if converting FROM to TO would involve a qualification
1636 conversion. */
1638 static bool
1640 {
1641 /* If we're not convering a pointer to another one, we won't get
1642 a qualification conversion. */
1654 }
1656 /* A reference of the indicated TYPE is being bound directly to the
1657 expression represented by the implicit conversion sequence CONV.
1658 Return a conversion sequence for this binding. */
1662 {
1663 tree t;
1671 /* Mark the identity conv as to not decay to rvalue. */
1674 /* [over.ics.rank]
1676 When a parameter of reference type binds directly
1677 (_dcl.init.ref_) to an argument expression, the implicit
1678 conversion sequence is the identity conversion, unless the
1679 argument expression has a type that is a derived class of the
1680 parameter type, in which case the implicit conversion sequence is
1681 a derived-to-base Conversion.
1683 If the parameter binds directly to the result of applying a
1684 conversion function to the argument expression, the implicit
1685 conversion sequence is a user-defined conversion sequence
1686 (_over.ics.user_), with the second standard conversion sequence
1687 either an identity conversion or, if the conversion function
1688 returns an entity of a type that is a derived class of the
1689 parameter type, a derived-to-base conversion. */
1691 {
1692 /* Represent the derived-to-base conversion. */
1694 /* We will actually be binding to the base-class subobject in
1695 the derived class, so we mark this conversion appropriately.
1696 That way, convert_like knows not to generate a temporary. */
1698 }
1700 /* Represent the qualification conversion. After DR 2352
1701 #1 and #2 were indistinguishable conversion sequences:
1703 void f(int*); // #1
1704 void f(const int* const &); // #2
1705 void g(int* p) { f(p); }
1707 because the types "int *" and "const int *const" are
1708 reference-related and we were binding both directly and they
1709 had the same rank. To break it up, we add a ck_qual under the
1710 ck_ref_bind so that conversion sequence ranking chooses #1.
1712 We strip_top_quals here which is also what standard_conversion
1713 does. Failure to do so would confuse comp_cv_qual_signature
1714 into thinking that in
1716 void f(const int * const &); // #1
1717 void f(const int *); // #2
1718 int *x;
1719 f(x);
1721 #2 is a better match than #1 even though they're ambiguous (97296). */
1725 }
1727 /* Returns the conversion path from type FROM to reference type TO for
1728 purposes of reference binding. For lvalue binding, either pass a
1729 reference type to FROM or an lvalue expression to EXPR. If the
1730 reference will be bound to a temporary, NEED_TEMPORARY_P is set for
1731 the conversion returned. If C_CAST_P is true, this
1732 conversion is coming from a C-style cast. */
1736 tsubst_flags_t complain)
1737 {
1741 tree tfrom;
1744 cp_lvalue_kind gl_kind;
1748 {
1753 }
1757 {
1759 /* DR 1288: Otherwise, if the initializer list has a single element
1760 of type E and ... [T's] referenced type is reference-related to E,
1761 the object or reference is initialized from that element...
1763 ??? With P0388R4, we should bind 't' directly to U{}:
1764 using U = A[2];
1765 A (&&t)[] = {U{}};
1766 because A[] and A[2] are reference-related. But we don't do it
1767 because grok_reference_init has deduced the array size (to 1), and
1768 A[1] and A[2] aren't reference-related. */
1771 {
1777 {
1781 }
1782 }
1783 /* Otherwise, if T is a reference type, a prvalue temporary of the type
1784 referenced by T is copy-list-initialized, and the reference is bound
1785 to that temporary. */
1787 skip:;
1788 }
1791 {
1796 else
1798 }
1804 else
1807 /* Don't allow a class prvalue when LOOKUP_NO_TEMP_BIND. */
1812 /* Same mask as real_lvalue_p. */
1819 /* Figure out whether or not the types are reference-related and
1820 reference compatible. We have to do this after stripping
1821 references from FROM. */
1823 /* If this is a C cast, first convert to an appropriately qualified
1824 type, so that we can later do a const_cast to the desired type. */
1830 /* Directly bind reference when target expression's type is compatible with
1831 the reference and expression is an lvalue. In DR391, the wording in
1832 [8.5.3/5 dcl.init.ref] is changed to also require direct bindings for
1833 const and rvalue references to rvalues of compatible class type.
1834 We should also do direct bindings for non-class xvalues. */
1836 {
1837 /* [dcl.init.ref]
1839 If the initializer expression
1841 -- is an lvalue (but not an lvalue for a bit-field), and "cv1 T1"
1842 is reference-compatible with "cv2 T2,"
1844 the reference is bound directly to the initializer expression
1845 lvalue.
1847 [...]
1848 If the initializer expression is an rvalue, with T2 a class type,
1849 and "cv1 T1" is reference-compatible with "cv2 T2", the reference
1850 is bound to the object represented by the rvalue or to a sub-object
1851 within that object. */
1857 /* Handle rvalue reference to function properly. */
1858 conv->rvaluedness_matches_p
1860 else
1861 conv->rvaluedness_matches_p
1866 /* For the purposes of overload resolution, we ignore the fact
1867 this expression is a bitfield or packed field. (In particular,
1868 [over.ics.ref] says specifically that a function with a
1869 non-const reference parameter is viable even if the
1870 argument is a bitfield.)
1872 However, when we actually call the function we must create
1873 a temporary to which to bind the reference. If the
1874 reference is volatile, or isn't const, then we cannot make
1875 a temporary, so we just issue an error when the conversion
1876 actually occurs. */
1879 /* Don't allow binding of lvalues (other than function lvalues) to
1880 rvalue references. */
1885 /* Nor the reverse. */
1887 /* Unless it's really a C++20 lvalue being treated as an xvalue.
1888 But in C++23, such an expression is just an xvalue, not a special
1889 lvalue, so the binding is once again ill-formed. */
1901 }
1902 /* [class.conv.fct] A conversion function is never used to convert a
1903 (possibly cv-qualified) object to the (possibly cv-qualified) same
1904 object type (or a reference to it), to a (possibly cv-qualified) base
1905 class of that type (or a reference to it).... */
1908 {
1909 /* [dcl.init.ref]
1911 If the initializer expression
1913 -- has a class type (i.e., T2 is a class type) can be
1914 implicitly converted to an lvalue of type "cv3 T3," where
1915 "cv1 T1" is reference-compatible with "cv3 T3". (this
1916 conversion is selected by enumerating the applicable
1917 conversion functions (_over.match.ref_) and choosing the
1918 best one through overload resolution. (_over.match_).
1920 the reference is bound to the lvalue result of the conversion
1921 in the second case. */
1923 complain);
1926 }
1928 /* From this point on, we conceptually need temporaries, even if we
1929 elide them. Only the cases above are "direct bindings". */
1933 /* [over.ics.rank]
1935 When a parameter of reference type is not bound directly to an
1936 argument expression, the conversion sequence is the one required
1937 to convert the argument expression to the underlying type of the
1938 reference according to _over.best.ics_. Conceptually, this
1939 conversion sequence corresponds to copy-initializing a temporary
1940 of the underlying type with the argument expression. Any
1941 difference in top-level cv-qualification is subsumed by the
1942 initialization itself and does not constitute a conversion. */
1946 /* [dcl.init.ref]
1948 Otherwise, the reference shall be an lvalue reference to a
1949 non-volatile const type, or the reference shall be an rvalue
1950 reference. */
1954 /* [dcl.init.ref]
1956 Otherwise, a temporary of type "cv1 T1" is created and
1957 initialized from the initializer expression using the rules for a
1958 non-reference copy initialization. If T1 is reference-related to
1959 T2, cv1 must be the same cv-qualification as, or greater
1960 cv-qualification than, cv2; otherwise, the program is ill-formed. */
1964 /* We try below to treat an invalid reference binding as a bad conversion
1965 to improve diagnostics, but doing so may cause otherwise unnecessary
1966 instantiations that can lead to a hard error. So during the first pass
1967 of overload resolution wherein we shortcut bad conversions, instead just
1968 produce a special conversion indicating a second pass is necessary if
1969 there's no strictly viable candidate. */
1971 {
1975 }
1977 /* We're generating a temporary now, but don't bind any more in the
1978 conversion (specifically, don't slice the temporary returned by a
1979 conversion operator). */
1982 /* Core issue 899: When [copy-]initializing a temporary to be bound
1983 to the first parameter of a copy constructor (12.8) called with
1984 a single argument in the context of direct-initialization,
1985 explicit conversion functions are also considered.
1987 So don't set LOOKUP_ONLYCONVERTING in that case. */
1998 {
2000 /* Remember this was copy-list-initialization. */
2003 /* If initializing the temporary used a conversion function,
2004 recalculate the second conversion sequence. */
2008 {
2010 /* A prvalue of non-class type is cv-unqualified. */
2014 conversion *new_second
2022 }
2023 }
2026 /* This reference binding, unlike those above, requires the
2027 creation of a temporary. */
2033 }
2035 /* Most of the implementation of implicit_conversion, with the same
2036 parameters. */
2041 {
2048 /* Other flags only apply to the primary function in overload
2049 resolution, or after we've chosen one. */
2054 /* FIXME: actually we don't want warnings either, but we can't just
2055 have 'complain &= ~(tf_warning|tf_error)' because it would cause
2056 the regression of, eg, g++.old-deja/g++.benjamin/16077.C.
2057 We really ought not to issue that warning until we've committed
2058 to that conversion. */
2061 /* Call reshape_init early to remove redundant braces. */
2063 {
2068 {
2073 }
2074 }
2078 else
2085 {
2089 /* As an extension, allow list-initialization of _Complex. */
2092 {
2096 }
2098 /* Allow conversion from an initializer-list with one element to a
2099 scalar type. */
2101 {
2103 tree elt;
2109 else
2115 {
2118 /* Too many levels of braces, i.e. '{{1}}'. */
2121 }
2122 }
2125 }
2131 {
2141 {
2146 {
2147 /* "If C is not an initializer-list constructor and the
2148 initializer list has a single element of type cv U, where U is
2149 X or a class derived from X, the implicit conversion sequence
2150 has Exact Match rank if U is X, or Conversion rank if U is
2151 derived from X." */
2157 }
2159 }
2161 /* We used to try to bind a reference to a temporary here, but that
2162 is now handled after the recursive call to this function at the end
2163 of reference_binding. */
2165 }
2168 }
2170 /* Returns the implicit conversion sequence (see [over.ics]) from type
2171 FROM to type TO. The optional expression EXPR may affect the
2172 conversion. FLAGS are the usual overloading flags. If C_CAST_P is
2173 true, this conversion is coming from a C-style cast. */
2178 {
2188 }
2190 /* Like implicit_conversion, but return NULL if the conversion is bad.
2192 This is not static so that check_non_deducible_conversion can call it within
2193 add_template_candidate_real as part of overload resolution; it should not be
2194 called outside of overload resolution. */
2196 conversion *
2199 {
2205 }
2207 /* Add a new entry to the list of candidates. Used by the add_*_candidate
2208 functions. ARGS will not be changed until a single candidate is
2209 selected. */
2218 {
2236 /* Swap the conversions for comparison in joust; we'll swap them back
2237 before build_over_call. */
2241 }
2243 /* Return the number of remaining arguments in the parameter list
2244 beginning with ARG. */
2246 int
2248 {
2253 n++;
2256 }
2258 /* [over.match.copy]: When initializing a temporary object (12.2) to be bound
2259 to the first parameter of a constructor where the parameter is of type
2260 "reference to possibly cv-qualified T" and the constructor is called with a
2261 single argument in the context of direct-initialization of an object of type
2262 "cv2 T", explicit conversion functions are also considered.
2264 So set LOOKUP_COPY_PARM to let reference_binding know that
2265 it's being called in that context. */
2267 int
2269 {
2271 tree t;
2274 && (same_type_ignoring_top_level_qualifiers_p
2276 {
2282 }
2283 else
2287 }
2289 /* Build an appropriate 'this' conversion for the method FN and class
2290 type CTYPE from the value ARG (having type ARGTYPE) to the type PARMTYPE.
2291 This function modifies PARMTYPE, ARGTYPE and ARG. */
2297 {
2301 /* The type of the implicit object parameter ('this') for
2302 overload resolution is not always the same as for the
2303 function itself; conversion functions are considered to
2304 be members of the class being converted, and functions
2305 introduced by a using-declaration are considered to be
2306 members of the class that uses them.
2308 Since build_over_call ignores the ICS for the `this'
2309 parameter, we can just change the parm type. */
2314 {
2315 /* If the function has a ref-qualifier, the implicit
2316 object parameter has reference type. */
2319 /* The special handling of 'this' conversions in compare_ics
2320 does not apply if there is a ref-qualifier. */
2322 }
2323 else
2324 {
2326 /* We don't use build_this here because we don't want to
2327 capture the object argument until we've chosen a
2328 non-static member function. */
2331 }
2337 }
2339 /* Create an overload candidate for the function or method FN called
2340 with the argument list FIRST_ARG/ARGS and add it to CANDIDATES.
2341 FLAGS is passed on to implicit_conversion.
2343 This does not change ARGS.
2345 CTYPE, if non-NULL, is the type we want to pretend this function
2346 comes from for purposes of overload resolution.
2348 SHORTCUT_BAD_CONVS controls how we handle "bad" argument conversions.
2349 If true, we stop computing conversions upon seeing the first bad
2350 conversion. This is used by add_candidates to avoid computing
2351 more conversions than necessary in the presence of a strictly viable
2352 candidate, while preserving the defacto behavior of overload resolution
2353 when it turns out there are only non-strictly viable candidates. */
2362 tsubst_flags_t complain)
2363 {
2366 tree parmnode;
2372 /* The `this', `in_chrg' and VTT arguments to constructors are not
2373 considered in overload resolution. */
2375 {
2377 /* Bring back parameters omitted from an inherited ctor. */
2379 else
2383 {
2386 }
2387 }
2388 else
2395 /* 13.3.2 - Viable functions [over.match.viable]
2396 First, to be a viable function, a candidate function shall have enough
2397 parameters to agree in number with the arguments in the list.
2399 We need to check this first; otherwise, checking the ICSes might cause
2400 us to produce an ill-formed template instantiation. */
2404 {
2408 }
2412 {
2416 }
2418 /* An inherited constructor (12.6.3 [class.inhctor.init]) that has a first
2419 parameter of type "reference to cv C" (including such a constructor
2420 instantiated from a template) is excluded from the set of candidate
2421 functions when used to construct an object of type D with an argument list
2422 containing a single argument if C is reference-related to D. */
2424 && flag_new_inheriting_ctors
2426 {
2432 {
2435 }
2436 }
2438 /* Second, for a function to be viable, its constraints must be
2439 satisfied. */
2441 {
2444 }
2446 /* When looking for a function from a subobject from an implicit
2447 copy/move constructor/operator=, don't consider anything that takes (a
2448 reference to) an unrelated type. See c++/44909 and core 1092. */
2450 {
2456 else
2459 {
2462 ctype))
2464 }
2466 /* This only applies at the top level. */
2468 }
2475 else
2478 /* Third, for F to be a viable function, there shall exist for each
2479 argument an implicit conversion sequence that converts that argument
2480 to the corresponding parameter of F. */
2485 {
2487 tree arg;
2493 {
2494 /* Already set during deduction. */
2497 }
2501 else
2508 {
2515 else
2516 {
2520 }
2523 }
2524 else
2525 {
2529 }
2533 {
2538 }
2541 {
2547 }
2548 }
2550 out:
2553 }
2555 /* Create an overload candidate for the conversion function FN which will
2556 be invoked for expression OBJ, producing a pointer-to-function which
2557 will in turn be called with the argument list FIRST_ARG/ARGLIST,
2558 and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
2559 passed on to implicit_conversion.
2561 Actually, we don't really care about FN; we care about the type it
2562 converts to. There may be multiple conversion functions that will
2563 convert to that type, and we rely on build_user_type_conversion_1 to
2564 choose the best one; so when we create our candidate, we record the type
2565 instead of the function. */
2571 tsubst_flags_t complain)
2572 {
2590 /* Don't bother looking up the same type twice. */
2595 {
2600 }
2603 {
2609 else
2614 {
2617 /* Leave the 'cand' field null; we'll figure out the conversion in
2618 convert_like if this candidate is chosen. */
2620 }
2624 {
2628 }
2629 else
2630 {
2634 }
2641 {
2645 }
2652 }
2656 {
2660 }
2664 }
2666 static void
2670 {
2684 /* TRUTH_*_EXPR do "contextual conversion to bool", which means explicit
2685 conversion ops are allowed. We handle that here by just checking for
2686 boolean_type_node because other operators don't ask for it. COND_EXPR
2687 also does contextual conversion to bool for the first operand, but we
2688 handle that in build_conditional_expr, and type1 here is operand 2. */
2693 {
2697 {
2699 /* We need something for printing the candidate. */
2703 }
2705 {
2710 }
2712 }
2714 /* For COND_EXPR we rearranged the arguments; undo that now. */
2716 {
2721 complain);
2724 else
2725 {
2728 boolean_type_node,
2730 }
2731 }
2738 }
2740 static bool
2742 {
2744 }
2746 /* Returns nonzero if TYPE is a promoted arithmetic type. */
2748 static bool
2750 {
2751 /* [over.built]
2753 In this section, the term promoted integral type is used to refer
2754 to those integral types which are preserved by integral promotion
2755 (including e.g. int and long but excluding e.g. char).
2756 Similarly, the term promoted arithmetic type refers to promoted
2757 integral types plus floating types. */
2761 }
2763 /* Create any builtin operator overload candidates for the operator in
2764 question given the converted operand types TYPE1 and TYPE2. The other
2765 args are passed through from add_builtin_candidates to
2766 build_builtin_candidate.
2768 TYPE1 and TYPE2 may not be permissible, and we must filter them.
2769 If CODE is requires candidates operands of the same type of the kind
2770 of which TYPE1 and TYPE2 are, we add both candidates
2771 CODE (TYPE1, TYPE1) and CODE (TYPE2, TYPE2). */
2773 static void
2778 {
2780 {
2788 }
2791 {
2793 /* 4 For every pair (T, VQ), where T is an arithmetic type other than bool,
2794 and VQ is either volatile or empty, there exist candidate operator
2795 functions of the form
2796 VQ T& operator++(VQ T&);
2797 T operator++(VQ T&, int);
2798 5 For every pair (T, VQ), where T is an arithmetic type other than bool,
2799 and VQ is either volatile or empty, there exist candidate operator
2800 functions of the form
2801 VQ T& operator--(VQ T&);
2802 T operator--(VQ T&, int);
2803 6 For every pair (T, VQ), where T is a cv-qualified or cv-unqualified object
2804 type, and VQ is either volatile or empty, there exist candidate operator
2805 functions of the form
2806 T*VQ& operator++(T*VQ&);
2807 T*VQ& operator--(T*VQ&);
2808 T* operator++(T*VQ&, int);
2809 T* operator--(T*VQ&, int); */
2815 /* FALLTHRU */
2818 /* P0002R1, Remove deprecated operator++(bool) added "other than bool"
2819 to p4. */
2823 {
2826 }
2829 /* 7 For every cv-qualified or cv-unqualified object type T, there
2830 exist candidate operator functions of the form
2832 T& operator*(T*);
2835 8 For every function type T that does not have cv-qualifiers or
2836 a ref-qualifier, there exist candidate operator functions of the form
2837 T& operator*(T*); */
2846 /* 9 For every type T, there exist candidate operator functions of the form
2847 T* operator+(T*);
2849 10 For every floating-point or promoted integral type T, there exist
2850 candidate operator functions of the form
2851 T operator+(T);
2852 T operator-(T); */
2857 /* FALLTHRU */
2863 /* 11 For every promoted integral type T, there exist candidate operator
2864 functions of the form
2865 T operator~(T); */
2872 /* 12 For every quintuple (C1, C2, T, CV1, CV2), where C2 is a class type, C1
2873 is the same type as C2 or is a derived class of C2, and T is an object
2874 type or a function type there exist candidate operator functions of the
2875 form
2876 CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
2877 where CV12 is the union of CV1 and CV2. */
2881 {
2889 }
2892 /* 13 For every pair of types L and R, where each of L and R is a floating-point
2893 or promoted integral type, there exist candidate operator functions of the
2894 form
2895 LR operator*(L, R);
2896 LR operator/(L, R);
2897 LR operator+(L, R);
2898 LR operator-(L, R);
2899 bool operator<(L, R);
2900 bool operator>(L, R);
2901 bool operator<=(L, R);
2902 bool operator>=(L, R);
2903 bool operator==(L, R);
2904 bool operator!=(L, R);
2905 where LR is the result of the usual arithmetic conversions between
2906 types L and R.
2908 14 For every integral type T there exists a candidate operator function of
2909 the form
2911 std::strong_ordering operator<=>(T, T);
2913 15 For every pair of floating-point types L and R, there exists a candidate
2914 operator function of the form
2916 std::partial_ordering operator<=>(L, R);
2918 16 For every cv-qualified or cv-unqualified object type T there exist
2919 candidate operator functions of the form
2920 T* operator+(T*, std::ptrdiff_t);
2921 T& operator[](T*, std::ptrdiff_t);
2922 T* operator-(T*, std::ptrdiff_t);
2923 T* operator+(std::ptrdiff_t, T*);
2924 T& operator[](std::ptrdiff_t, T*);
2926 17 For every T, where T is a pointer to object type, there exist candidate
2927 operator functions of the form
2928 std::ptrdiff_t operator-(T, T);
2930 18 For every T, where T is an enumeration type or a pointer type, there
2931 exist candidate operator functions of the form
2932 bool operator<(T, T);
2933 bool operator>(T, T);
2934 bool operator<=(T, T);
2935 bool operator>=(T, T);
2936 bool operator==(T, T);
2937 bool operator!=(T, T);
2938 R operator<=>(T, T);
2940 where R is the result type specified in [expr.spaceship].
2942 19 For every T, where T is a pointer-to-member type or std::nullptr_t,
2943 there exist candidate operator functions of the form
2944 bool operator==(T, T);
2945 bool operator!=(T, T); */
2952 {
2955 }
2956 /* FALLTHRU */
2963 /* This isn't exactly what's specified above for operator<=>, but it's
2964 close enough. In particular, we don't care about the return type
2965 specified above; it doesn't participate in overload resolution and it
2966 doesn't affect the semantics of the built-in operator. */
2976 {
2979 }
2981 {
2984 }
2985 /* Fall through. */
3001 {
3004 }
3007 {
3010 }
3016 /* FALLTHRU */
3019 {
3022 }
3024 {
3027 }
3030 /* 18For every pair of promoted integral types L and R, there exist candi-
3031 date operator functions of the form
3032 LR operator%(L, R);
3033 LR operator&(L, R);
3034 LR operator^(L, R);
3035 LR operator|(L, R);
3036 L operator<<(L, R);
3037 L operator>>(L, R);
3038 where LR is the result of the usual arithmetic conversions between
3039 types L and R. */
3047 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
3051 /* 19For every triple L, VQ, R), where L is an arithmetic or enumeration
3052 type, VQ is either volatile or empty, and R is a promoted arithmetic
3053 type, there exist candidate operator functions of the form
3054 VQ L& operator=(VQ L&, R);
3055 VQ L& operator*=(VQ L&, R);
3056 VQ L& operator/=(VQ L&, R);
3057 VQ L& operator+=(VQ L&, R);
3058 VQ L& operator-=(VQ L&, R);
3060 20For every pair T, VQ), where T is any type and VQ is either volatile
3061 or empty, there exist candidate operator functions of the form
3062 T*VQ& operator=(T*VQ&, T*);
3064 21For every pair T, VQ), where T is a pointer to member type and VQ is
3065 either volatile or empty, there exist candidate operator functions of
3066 the form
3067 VQ T& operator=(VQ T&, T);
3069 22For every triple T, VQ, I), where T is a cv-qualified or cv-
3070 unqualified complete object type, VQ is either volatile or empty, and
3071 I is a promoted integral type, there exist candidate operator func-
3072 tions of the form
3073 T*VQ& operator+=(T*VQ&, I);
3074 T*VQ& operator-=(T*VQ&, I);
3076 23For every triple L, VQ, R), where L is an integral or enumeration
3077 type, VQ is either volatile or empty, and R is a promoted integral
3078 type, there exist candidate operator functions of the form
3080 VQ L& operator%=(VQ L&, R);
3081 VQ L& operator<<=(VQ L&, R);
3082 VQ L& operator>>=(VQ L&, R);
3083 VQ L& operator&=(VQ L&, R);
3084 VQ L& operator^=(VQ L&, R);
3085 VQ L& operator|=(VQ L&, R); */
3089 {
3093 {
3096 }
3097 /* FALLTHRU */
3110 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
3123 {
3126 }
3131 }
3136 /* [over.built]
3138 For every pair of promoted arithmetic types L and R, there
3139 exist candidate operator functions of the form
3141 LR operator?(bool, L, R);
3143 where LR is the result of the usual arithmetic conversions
3144 between types L and R.
3146 For every type T, where T is a pointer or pointer-to-member
3147 type, there exist candidate operator functions of the form T
3148 operator?(bool, T, T); */
3152 /* That's OK. */
3155 /* Otherwise, the types should be pointers. */
3159 /* We don't check that the two types are the same; the logic
3160 below will actually create two candidates; one in which both
3161 parameter types are TYPE1, and one in which both parameter
3162 types are TYPE2. */
3173 }
3175 /* Make sure we don't create builtin candidates with dependent types. */
3179 {
3180 /* Try to recover if one of the types is non-dependent. But if
3181 there's only one type, there's nothing we can do. */
3184 /* And we lose if both are dependent. */
3187 /* Or if they have different forms. */
3195 }
3197 /* If we're dealing with two pointer types or two enumeral types,
3198 we need candidates for both of them. */
3207 {
3209 {
3212 error_mark_node,
3213 error_mark_node,
3214 CPO_CONVERSION,
3215 tf_none);
3217 {
3218 build_builtin_candidate
3222 }
3223 }
3225 build_builtin_candidate
3227 build_builtin_candidate
3230 }
3232 build_builtin_candidate
3234 }
3236 tree
3238 {
3244 }
3246 /* There are three conditions of builtin candidates:
3248 1) bool-taking candidates. These are the same regardless of the input.
3249 2) pointer-pair taking candidates. These are generated for each type
3250 one of the input types converts to.
3251 3) arithmetic candidates. According to the standard, we should generate
3252 all of these, but I'm trying not to...
3254 Here we generate a superset of the possible candidates for this particular
3255 case. That is a subset of the full set the standard defines, plus some
3256 other cases which the standard disallows. add_builtin_candidate will
3257 filter out the invalid set. */
3259 static void
3264 {
3268 /* TYPES[i] is the set of possible builtin-operator parameter types
3269 we will consider for the Ith argument. */
3276 {
3279 else
3281 }
3284 {
3285 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
3286 and VQ is either volatile or empty, there exist candidate operator
3287 functions of the form
3288 VQ T& operator++(VQ T&); */
3298 /* 24There also exist candidate operator functions of the form
3299 bool operator!(bool);
3300 bool operator&&(bool, bool);
3301 bool operator||(bool, bool); */
3304 build_builtin_candidate
3311 build_builtin_candidate
3331 /* Fall through. */
3335 }
3343 {
3345 {
3346 tree convs;
3354 {
3359 }
3365 {
3378 {
3384 }
3388 }
3389 }
3390 else
3391 {
3396 {
3402 }
3404 }
3405 }
3407 /* Run through the possible parameter types of both arguments,
3408 creating candidates with those parameter types. */
3410 {
3412 tree u;
3416 add_builtin_candidate
3419 else
3420 add_builtin_candidate
3423 }
3427 }
3430 /* If TMPL can be successfully instantiated as indicated by
3431 EXPLICIT_TARGS and ARGLIST, adds the instantiation to CANDIDATES.
3433 TMPL is the template. EXPLICIT_TARGS are any explicit template
3434 arguments. ARGLIST is the arguments provided at the call-site.
3435 This does not change ARGLIST. The RETURN_TYPE is the desired type
3436 for conversion operators. If OBJ is NULL_TREE, FLAGS and CTYPE are
3437 as for add_function_candidate. If an OBJ is supplied, FLAGS and
3438 CTYPE are ignored, and OBJ is as for add_conv_candidate.
3440 SHORTCUT_BAD_CONVS is as in add_function_candidate. */
3449 {
3459 tree arg;
3461 tree fn;
3466 /* We don't do deduction on the in-charge parameter, the VTT
3467 parameter or 'this'. */
3469 {
3473 /* We're deducing for a call to the result of a template conversion
3475 else
3477 }
3482 {
3485 else
3487 }
3495 {
3496 /* 12.8/6 says, "A declaration of a constructor for a class X is
3497 ill-formed if its first parameter is of type (optionally cv-qualified)
3498 X and either there are no other parameters or else all other
3499 parameters have default arguments. A member function template is never
3500 instantiated to produce such a constructor signature."
3502 So if we're trying to copy an object of the containing class, don't
3503 consider a template constructor that has a first parameter type that
3504 is just a template parameter, as we would deduce a signature that we
3505 would then reject in the code below. */
3507 {
3512 {
3516 }
3517 }
3518 }
3525 {
3528 }
3532 {
3535 }
3539 {
3540 /* Check that there's no obvious arity mismatch before proceeding with
3541 deduction. This avoids substituting explicit template arguments
3542 into the template or e.g. derived-to-base parm/arg unification
3543 (which could result in an error outside the immediate context) when
3544 the resulting candidate would be unviable anyway. */
3549 {
3551 {
3554 }
3556 /* A parameter with a default argument. */
3558 else
3560 }
3562 {
3563 /* Too few arguments. */
3567 }
3569 {
3570 /* Too many arguments. */
3573 }
3580 {
3581 /* Check the 'this' conversion before proceeding with deduction.
3582 This is effectively an extension of the DR 1391 resolution
3583 that we perform in check_non_deducible_conversions, though it's
3584 convenient to do this extra check here instead of there. */
3593 {
3598 }
3599 }
3600 }
3604 args_without_in_chrg,
3605 nargs_without_in_chrg,
3610 {
3611 /* Don't repeat unification later if it already resulted in errors. */
3615 nargs_without_in_chrg,
3617 else
3620 }
3622 /* Now the explicit specifier might have been deduced; check if this
3623 declaration is explicit. If it is and we're ignoring non-converting
3624 constructors, don't add this function to the set of candidates. */
3631 {
3634 ctype))
3635 {
3636 /* We're trying to produce a constructor with a prohibited signature,
3637 as discussed above; handle here any cases we didn't catch then,
3638 such as X(X<T>). */
3641 }
3642 }
3645 /* Aha, this is a conversion function. */
3648 else
3654 /* This situation can occur if a member template of a template
3655 class is specialized. Then, instantiate_template might return
3656 an instantiation of the specialization, in which case the
3657 DECL_TI_TEMPLATE field will point at the original
3658 specialization. For example:
3660 template <class T> struct S { template <class U> void f(U);
3661 template <> void f(int) {}; };
3662 S<double> sd;
3663 sd.f(3);
3665 Here, TMPL will be template <class U> S<double>::f(U).
3666 And, instantiate template will give us the specialization
3667 template <> S<double>::f(int). But, the DECL_TI_TEMPLATE field
3668 for this will point at template <class T> template <> S<T>::f(int),
3669 so that we can find the definition. For the purposes of
3670 overload resolution, however, we want the original TMPL. */
3672 else
3677 fail:
3681 }
3690 tsubst_flags_t complain)
3691 {
3692 return
3697 complain);
3698 }
3700 /* Create an overload candidate for the conversion function template TMPL,
3701 returning RETURN_TYPE, which will be invoked for expression OBJ to produce a
3702 pointer-to-function which will in turn be called with the argument list
3703 ARGLIST, and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
3704 passed on to implicit_conversion. */
3708 tree obj,
3712 {
3713 return
3718 }
3720 /* The CANDS are the set of candidates that were considered for
3721 overload resolution. Return the set of viable candidates, or CANDS
3722 if none are viable. If any of the candidates were viable, set
3723 *ANY_VIABLE_P to true. STRICT_P is true if a candidate should be
3724 considered viable only if it is strictly viable. */
3730 {
3736 /* Be strict inside templates, since build_over_call won't actually
3737 do the conversions to get pedwarns. */
3747 {
3751 {
3752 /* Be strict in the presence of a viable candidate. Also if
3753 there are template candidates, so that we get deduction errors
3754 for them instead of silently preferring a bad conversion. */
3757 {
3758 /* Put any spliced near matches back onto the main list so
3759 that we see them if there is no strict match. */
3765 }
3766 }
3769 {
3777 }
3778 else
3780 }
3783 }
3785 static bool
3787 {
3792 }
3794 /* OBJ is being used in an expression like "OBJ.f (...)". In other
3795 words, it is about to become the "this" pointer for a member
3796 function call. Take the address of the object. */
3798 static tree
3800 {
3801 /* In a template, we are only concerned about the type of the
3802 expression, so we can take a shortcut. */
3807 }
3809 /* Returns true iff functions are equivalent. Equivalent functions are
3810 not '==' only if one is a function-local extern function or if
3811 both are extern "C". */
3815 {
3824 }
3826 /* Print information about a candidate FN being rejected due to INFO. */
3828 static void
3830 tree fn)
3831 {
3836 {
3837 /* Conversion of implicit `this' argument failed. */
3839 /* A bad conversion for 'this' must be discarding cv-quals. */
3842 from);
3843 else
3847 }
3849 {
3855 tf_warning_or_error);
3856 }
3858 /* Conversion of conversion function return value failed. */
3861 else
3862 {
3867 }
3868 }
3870 /* Print information about a candidate with WANT parameters and we found
3871 HAVE. */
3873 static void
3876 {
3882 else
3887 }
3889 /* Print information about one overload candidate CANDIDATE. MSGSTR
3890 is the text to print before the candidate itself.
3892 NOTE: Unlike most diagnostic functions in GCC, MSGSTR is expected
3893 to have been run through gettext by the caller. This wart makes
3894 life simpler in print_z_candidates and for the translators. */
3896 static void
3899 {
3909 {
3920 else
3923 }
3934 else
3937 {
3940 }
3941 /* Give the user some information about why this candidate failed. */
3943 {
3947 {
3961 "cannot be converted to %qT with a qualification "
3967 "conversion function specialization to %qT is not an "
3972 /* We use template_unification_error_rejection if unification caused
3973 actual non-SFINAE errors, in which case we don't need to repeat
3974 them here. */
3976 {
3980 }
3981 /* Re-run template unification with diagnostics. */
3985 (make_tree_vec
3996 " a constructor taking a single argument of its own "
4004 "initialization from an expression of the same or derived "
4009 /* This candidate didn't have any issues or we failed to
4010 handle a particular code. Either way... */
4012 }
4013 }
4014 }
4016 static void
4018 {
4025 /* Remove non-viable deleted candidates. */
4028 {
4033 else
4035 }
4036 /* ...if there are any non-deleted ones. */
4040 /* There may be duplicates in the set of candidates. We put off
4041 checking this condition as long as possible, since we have no way
4042 to eliminate duplicates from a set of functions in less than n^2
4043 time. Now we are about to emit an error message, so it is more
4044 permissible to go slowly. */
4046 {
4048 /* Skip builtin candidates and conversion functions. */
4053 {
4057 else
4059 }
4060 }
4064 }
4066 /* USER_SEQ is a user-defined conversion sequence, beginning with a
4067 USER_CONV. STD_SEQ is the standard conversion sequence applied to
4068 the result of the conversion function to convert it to the final
4069 desired type. Merge the two sequences into a single sequence,
4070 and return the merged sequence. */
4074 {
4080 /* Find the end of the second conversion sequence. */
4082 {
4083 /* The entire sequence is a user-conversion sequence. */
4087 }
4090 /* We're binding a reference directly to the result of the conversion.
4091 build_user_type_conversion_1 stripped the REFERENCE_TYPE from the return
4092 type, but we want it back. */
4095 /* Replace the identity conversion with the user conversion
4096 sequence. */
4100 }
4102 /* Handle overload resolution for initializing an object of class type from
4103 an initializer list. First we look for a suitable constructor that
4104 takes a std::initializer_list; if we don't find one, we then look for a
4105 non-list constructor.
4107 Parameters are as for add_candidates, except that the arguments are in
4108 the form of a CONSTRUCTOR (the initializer list) rather than a vector, and
4109 the RETURN_TYPE parameter is replaced by TOTYPE, the desired type. */
4111 static void
4118 tsubst_flags_t complain)
4119 {
4122 /* We're looking for a ctor for list-initialization. */
4124 /* And we don't allow narrowing conversions. We also use this flag to
4125 avoid the copy constructor call for copy-list-initialization. */
4131 /* Always use the default constructor if the list is empty (DR 990). */
4134 ;
4137 {
4142 }
4143 /* If the class has a list ctor, try passing the list as a single
4144 argument first, but only consider list ctors. */
4146 {
4153 }
4155 /* Expand the CONSTRUCTOR into a new argument vec. */
4163 /* We aren't looking for list-ctors anymore. */
4165 /* We allow more user-defined conversions within an init-list. */
4171 }
4173 /* Given C(std::initializer_list<A>), return A. */
4175 static tree
4177 {
4183 }
4185 /* If EXPR is a braced-init-list where the elements all decay to the same type,
4186 return that type. */
4188 static tree
4190 {
4199 {
4206 }
4208 }
4210 /* True iff EXPR contains any temporaries with non-trivial destruction.
4212 ??? Also ignore classes with non-trivial but no-op destruction other than
4213 std::allocator? */
4215 static bool
4217 {
4221 {
4226 }
4228 }
4230 /* We're initializing an array of ELTTYPE from INIT. If it seems useful,
4231 return INIT as an array (of its own type) so the caller can initialize the
4232 target array in a loop. */
4234 static tree
4236 {
4237 /* Only do this if the array can go in rodata but not once converted. */
4244 /* Check with a stub expression to weed out special cases, and check whether
4245 we call the same function for direct-init as copy-list-init. */
4246 conversion_obstack_sentinel cos;
4258 tf_none);
4265 /* Let the normal code give the error. */
4268 /* Don't do this if the conversion would be constant. */
4273 /* We can't do this if the conversion creates temporaries that need
4274 to live until the whole array is initialized. */
4278 /* We can't do this if copying from the initializer_list would be
4279 ill-formed. */
4291 }
4293 /* If we were going to call e.g. vector(initializer_list<string>) starting
4294 with a list of string-literals (which is inefficient, see PR105838),
4295 instead build an array of const char* and pass it to the range constructor.
4296 But only do this for standard library types, where we can assume the
4297 transformation makes sense.
4299 Really the container classes should have initializer_list<U> constructors to
4300 get the same effect more simply; this is working around that lack. */
4302 static tree
4304 {
4309 {
4312 {
4320 }
4321 }
4324 }
4326 /* Returns the best overload candidate to perform the requested
4327 conversion. This function is used for three the overloading situations
4328 described in [over.match.copy], [over.match.conv], and [over.match.ref].
4329 If TOTYPE is a REFERENCE_TYPE, we're trying to find a direct binding as
4330 per [dcl.init.ref], so we ignore temporary bindings. */
4334 tsubst_flags_t complain)
4335 {
4337 tree fromtype;
4351 /* We represent conversion within a hierarchy using RVALUE_CONV and
4352 BASE_CONV, as specified by [over.best.ics]; these become plain
4353 constructor calls, as specified in [dcl.init]. */
4358 /* Use lookup_fnfields_slot instead of lookup_fnfields to avoid
4359 creating a garbage BASELINK; constructors can't be inherited. */
4364 {
4368 {
4369 /* [class.conv.fct] A conversion function is never used to
4370 convert a (possibly cv-qualified) object to the (possibly
4371 cv-qualified) same object type (or a reference to it), to a
4372 (possibly cv-qualified) base class of that type (or a
4373 reference to it)... */
4374 }
4375 else
4377 }
4383 /* Prevent add_candidates from treating a non-strictly viable candidate
4384 as unviable. */
4387 /* It's OK to bind a temporary for converting constructor arguments, but
4388 not in converting the return value of a conversion operator. */
4394 {
4399 /* We should never try to call the abstract or base constructor
4400 from here. */
4406 {
4407 /* List-initialization. */
4411 }
4412 else
4413 {
4417 }
4420 {
4423 /* If totype isn't a reference, and LOOKUP_ONLYCONVERTING is
4424 set, then this is copy-initialization. In that case, "The
4425 result of the call is then used to direct-initialize the
4426 object that is the destination of the copy-initialization."
4427 [dcl.init]
4429 We represent this in the conversion sequence with an
4430 rvalue conversion, which means a constructor call. */
4435 cand->second_conv
4437 }
4438 }
4441 {
4444 else
4446 }
4449 {
4453 /* If LOOKUP_NO_CONVERSION, don't consider a conversion function that
4454 would need an addional user-defined conversion, i.e. if the return
4455 type differs in class-ness from the desired type. So we avoid
4456 considering operator bool when calling a copy constructor.
4458 This optimization avoids the failure in PR97600, and is allowed by
4459 [temp.inst]/9: "If the function selected by overload resolution can be
4460 determined without instantiating a class template definition, it is
4461 unspecified whether that instantiation actually takes place." */
4469 /* If we are called to convert to a reference type, we are trying to
4470 find a direct binding, so don't even consider temporaries. If
4471 we don't find a direct binding, the caller will try again to
4472 look for a temporary binding. */
4483 {
4485 /* Already rejected, don't change to -1. */
4489 conversion *ics
4491 rettype,
4494 complain);
4496 /* If LOOKUP_NO_TEMP_BIND isn't set, then this is
4497 copy-initialization. In that case, "The result of the
4498 call is then used to direct-initialize the object that is
4499 the destination of the copy-initialization." [dcl.init]
4501 We represent this in the conversion sequence with an
4502 rvalue conversion, which means a constructor call. But
4503 don't add a second rvalue conversion if there's already
4504 one there. Which there really shouldn't be, but it's
4505 harmless since we'd add it here anyway. */
4513 {
4518 }
4520 /* Limit this to non-templates for now (PR90546). */
4523 {
4524 /* If we are called to convert to a reference type, we are trying
4525 to find a direct binding per [over.match.ref], so rvaluedness
4526 must match for non-functions. */
4528 }
4531 {
4532 /* 13.3.1.5: For direct-initialization, those explicit
4533 conversion functions that are not hidden within S and
4534 yield type T or a type that can be converted to type T
4535 with a qualification conversion (4.4) are also candidate
4536 functions. */
4537 /* 13.3.1.6 doesn't have a parallel restriction, but it should;
4538 I've raised this issue with the committee. --jason 9/2011 */
4541 }
4543 {
4545 cand->reason
4549 }
4552 {
4553 /* 13.3.3.1.2: If the user-defined conversion is specified by
4554 a specialization of a conversion function template, the
4555 second standard conversion sequence shall have exact match
4556 rank. */
4559 }
4560 }
4561 }
4565 {
4569 }
4573 {
4575 {
4576 auto_diagnostic_group d;
4581 }
4590 /* If there are viable candidates, don't set ICS_BAD_FLAG; an
4591 ambiguous conversion is no worse than another user-defined
4592 conversion. */
4595 }
4597 /* Maybe pass { } as iterators instead of an initializer_list. */
4602 {
4605 }
4607 tree convtype;
4611 /* DR 5: [in the first step of copy-initialization]...if the function
4612 is a constructor, the call initializes a temporary of the
4613 cv-unqualified version of the destination type. */
4615 else
4617 /* Build the user conversion sequence. */
4618 conv = build_conv
4620 convtype,
4626 /* Remember that this was a list-initialization. */
4630 /* Combine it with the second conversion sequence. */
4635 }
4637 /* Wrapper for above. */
4639 tree
4641 tsubst_flags_t complain)
4642 {
4644 tree ret;
4648 conversion_obstack_sentinel cos;
4653 {
4656 else
4657 {
4660 }
4661 }
4662 else
4666 }
4668 /* Give a helpful diagnostic when implicit_conversion fails. */
4670 static void
4672 {
4675 /* If expr has unknown type, then it is an overloaded function.
4676 Call instantiate_type to get good error messages. */
4686 else
4687 {
4692 }
4693 }
4695 /* Worker for build_converted_constant_expr. */
4697 static tree
4700 {
4702 tree t;
4708 conversion_obstack_sentinel cos;
4713 /* A converted constant expression of type T is an expression, implicitly
4714 converted to type T, where the converted expression is a constant
4715 expression and the implicit conversion sequence contains only
4717 * user-defined conversions,
4718 * lvalue-to-rvalue conversions (7.1),
4719 * array-to-pointer conversions (7.2),
4720 * function-to-pointer conversions (7.3),
4721 * qualification conversions (7.5),
4722 * integral promotions (7.6),
4723 * integral conversions (7.8) other than narrowing conversions (11.6.4),
4724 * null pointer conversions (7.11) from std::nullptr_t,
4725 * null member pointer conversions (7.12) from std::nullptr_t, and
4726 * function pointer conversions (7.13),
4728 and where the reference binding (if any) binds directly. */
4733 {
4735 {
4736 /* A conversion function is OK. If it isn't constexpr, we'll
4737 complain later that the argument isn't constant. */
4739 /* List-initialization is OK. */
4741 /* The lvalue-to-rvalue conversion is OK. */
4743 /* Array-to-pointer and function-to-pointer. */
4745 /* Function pointer conversions. */
4747 /* Qualification conversions. */
4753 {
4759 }
4769 /* Integral promotion or conversion. */
4772 /* Conversion from nullptr to pointer or pointer-to-member. */
4778 /* fall through. */
4783 }
4784 }
4786 /* Avoid confusing convert_nontype_argument by introducing
4787 a redundant conversion to the same reference type. */
4790 {
4794 }
4797 {
4798 /* Don't copy a class in a template. */
4803 /* Issuing conversion warnings for value-dependent expressions is
4804 likely too noisy. */
4809 }
4810 else
4811 {
4815 }
4818 }
4820 /* Subroutine of convert_nontype_argument.
4822 EXPR is an expression used in a context that requires a converted
4823 constant-expression, such as a template non-type parameter. Do any
4824 necessary conversions (that are permitted for converted
4825 constant-expressions) to convert it to the desired type.
4827 This function doesn't consider explicit conversion functions. If
4828 you mean to use "a contextually converted constant expression of type
4829 bool", use build_converted_constant_bool_expr.
4831 If conversion is successful, returns the converted expression;
4832 otherwise, returns error_mark_node. */
4834 tree
4836 {
4838 complain);
4839 }
4841 /* Used to create "a contextually converted constant expression of type
4842 bool". This differs from build_converted_constant_expr in that it
4843 also considers explicit conversion functions. */
4845 tree
4847 {
4850 }
4852 /* Do any initial processing on the arguments to a function call. */
4856 {
4858 tree arg;
4861 {
4865 {
4870 }
4874 /* Force auto deduction now. Omit tf_warning to avoid redundant
4875 deprecated warning on deprecated-14.C. */
4878 }
4880 }
4882 /* Perform overload resolution on FN, which is called with the ARGS.
4884 Return the candidate function selected by overload resolution, or
4885 NULL if the event that overload resolution failed. In the case
4886 that overload resolution fails, *CANDIDATES will be the set of
4887 candidates considered, and ANY_VIABLE_P will be set to true or
4888 false to indicate whether or not any of the candidates were
4889 viable.
4891 The ARGS should already have gone through RESOLVE_ARGS before this
4892 function is called. */
4899 {
4901 tree explicit_targs;
4912 /* Check FN. */
4916 {
4920 }
4922 /* Add the various candidate functions. */
4927 LOOKUP_NORMAL,
4933 else
4937 }
4939 /* Print an error message about being unable to build a call to FN with
4940 ARGS. ANY_VIABLE_P indicates whether any candidate functions could
4941 be located; CANDIDATES is a possibly empty list of such
4942 functions. */
4944 static void
4947 {
4950 {
4953 }
4959 auto_diagnostic_group d;
4963 else
4968 }
4970 /* Perform overload resolution on the set of deduction guides DGUIDES
4971 using ARGS. Returns the selected deduction guide, or error_mark_node
4972 if overload resolution fails. */
4974 tree
4976 tsubst_flags_t complain)
4977 {
4980 tree result;
4984 conversion_obstack_sentinel cos;
4989 {
4993 }
4994 else
4998 }
5000 /* Return an expression for a call to FN (a namespace-scope function,
5001 or a static member function) with the ARGS. This may change
5002 ARGS. */
5004 tree
5006 tsubst_flags_t complain)
5007 {
5010 tree result;
5013 {
5017 }
5022 conversion_obstack_sentinel cos;
5025 complain);
5028 {
5030 {
5031 // If there is a single (non-viable) function candidate,
5032 // let the error be diagnosed by cp_build_function_call_vec.
5037 // Otherwise, emit notes for non-viable candidates.
5039 }
5041 }
5042 else
5043 {
5045 }
5048 && result
5055 }
5057 /* Build a call to a global operator new. FNNAME is the name of the
5058 operator (either "operator new" or "operator new[]") and ARGS are
5059 the arguments provided. This may change ARGS. *SIZE points to the
5060 total number of bytes required by the allocation, and is updated if
5061 that is changed here. *COOKIE_SIZE is non-NULL if a cookie should
5062 be used. If this function determines that no cookie should be
5063 used, after all, *COOKIE_SIZE is set to NULL_TREE. If SIZE_CHECK
5064 is not NULL_TREE, it is evaluated before calculating the final
5065 array size, and if it fails, the array size is replaced with
5066 (size_t)-1 (usually triggering a std::bad_alloc exception). If FN
5067 is non-NULL, it will be set, upon return, to the allocation
5068 function called. */
5070 tree
5075 {
5077 tree fns;
5084 /* Set to (size_t)-1 if the size check fails. */
5086 {
5092 }
5098 conversion_obstack_sentinel cos;
5100 /* Based on:
5102 [expr.new]
5104 If this lookup fails to find the name, or if the allocated type
5105 is not a class type, the allocation function's name is looked
5106 up in the global scope.
5108 we disregard block-scope declarations of "operator new". */
5112 {
5119 /* If no aligned allocation function matches, try again without the
5120 alignment. */
5121 }
5123 /* Figure out what function is being called. */
5126 complain);
5128 /* If no suitable function could be found, issue an error message
5129 and give up. */
5131 {
5135 }
5137 /* If a cookie is required, add some extra space. Whether
5138 or not a cookie is required cannot be determined until
5139 after we know which function was called. */
5141 {
5143 tree arg_types;
5146 /* Skip the size_t parameter. */
5148 /* Check the remaining parameters (if any). */
5152 ptr_type_node))
5154 /* If we need a cookie, adjust the number of bytes allocated. */
5156 {
5157 /* Update the total size. */
5160 {
5161 /* Set to (size_t)-1 if the size check fails. */
5165 }
5166 /* Update the argument list to reflect the adjusted size. */
5168 }
5169 else
5171 }
5173 /* Tell our caller which function we decided to call. */
5177 /* Build the CALL_EXPR. */
5180 /* Set this flag for all callers of this function. In addition to
5181 new-expressions, this is called for allocating coroutine state; treat
5182 that as an implicit new-expression. */
5188 }
5190 /* Evaluate side-effects from OBJ before evaluating call
5191 to FN in RESULT expression.
5192 This is for expressions of the form `obj->fn(...)'
5193 where `fn' turns out to be a static member function and
5194 `obj' needs to be evaluated. `fn' could be also static operator[]
5195 or static operator(), in which cases the source expression
5196 would be `obj[...]' or `obj(...)'. */
5198 tree
5200 {
5207 /* But avoid the implicit lvalue-rvalue conversion when `obj' is
5208 volatile. */
5215 }
5217 /* Build a new call to operator(). This may change ARGS. */
5219 tree
5221 {
5239 {
5241 /* It's no good looking for an overloaded operator() on a
5242 pointer-to-member-function. */
5246 }
5249 {
5253 }
5254 else
5258 {
5262 }
5264 conversion_obstack_sentinel cos;
5267 {
5275 }
5282 {
5290 {
5295 {
5296 /* Making this work broke PR 71117 and 85118, so until the
5297 committee resolves core issue 2189, let's disable this
5298 candidate if there are any call operators. */
5302 add_template_conv_candidate
5306 }
5307 else
5311 }
5312 }
5314 /* Be strict here because if we choose a bad conversion candidate, the
5315 errors we get won't mention the call context. */
5318 {
5320 {
5321 auto_diagnostic_group d;
5325 }
5327 }
5328 else
5329 {
5332 {
5334 {
5335 auto_diagnostic_group d;
5339 }
5341 }
5345 {
5347 /* In an expression of the form `a()' where cand->fn
5348 which is operator() turns out to be a static member function,
5349 `a' is none-the-less evaluated. */
5351 }
5352 else
5353 {
5357 else
5358 {
5361 }
5364 }
5365 }
5368 }
5370 /* Called by op_error to prepare format strings suitable for the error
5371 function. It concatenates a prefix (controlled by MATCH), ERRMSG,
5372 and a suffix (controlled by NTYPES). */
5376 {
5386 else
5390 }
5392 static void
5396 {
5401 {
5407 else
5419 else
5429 else
5440 else
5449 else
5458 {
5463 }
5464 else
5469 else
5473 else
5478 }
5479 }
5481 /* Return the implicit conversion sequence that could be used to
5482 convert E1 to E2 in [expr.cond]. */
5486 {
5492 /* [expr.cond]
5494 If E2 is an lvalue: E1 can be converted to match E2 if E1 can be
5495 implicitly converted (clause _conv_) to the type "lvalue reference to
5496 T2", subject to the constraint that in the conversion the
5497 reference must bind directly (_dcl.init.ref_) to an lvalue.
5499 If E2 is an xvalue: E1 can be converted to match E2 if E1 can be
5500 implicitly converted to the type "rvalue reference to T2", subject to
5501 the constraint that the reference must bind directly. */
5503 {
5506 t1,
5507 e1,
5509 LOOKUP_NO_TEMP_BIND|LOOKUP_NO_RVAL_BIND
5511 complain);
5514 }
5516 /* If E2 is a prvalue or if neither of the conversions above can be done
5517 and at least one of the operands has (possibly cv-qualified) class
5518 type: */
5522 /* [expr.cond]
5524 If E1 and E2 have class type, and the underlying class types are
5525 the same or one is a base class of the other: E1 can be converted
5526 to match E2 if the class of T2 is the same type as, or a base
5527 class of, the class of T1, and the cv-qualification of T2 is the
5528 same cv-qualification as, or a greater cv-qualification than, the
5529 cv-qualification of T1. If the conversion is applied, E1 is
5530 changed to an rvalue of type T2 that still refers to the original
5531 source class object (or the appropriate subobject thereof). */
5534 {
5536 {
5541 else
5544 }
5545 else
5547 }
5548 else
5549 /* [expr.cond]
5551 Otherwise: E1 can be converted to match E2 if E1 can be implicitly
5552 converted to the type that expression E2 would have if E2 were
5553 converted to an rvalue (or the type it has, if E2 is an rvalue). */
5556 }
5558 /* Implement [expr.cond]. ARG1, ARG2, and ARG3 are the three
5559 arguments to the conditional expression. */
5561 tree
5564 tsubst_flags_t complain)
5565 {
5566 tree arg2_type;
5567 tree arg3_type;
5578 /* As a G++ extension, the second argument to the conditional can be
5579 omitted. (So that `a ? : c' is roughly equivalent to `a ? a :
5580 c'.) If the second operand is omitted, make sure it is
5581 calculated only once. */
5583 {
5586 "ISO C++ forbids omitting the middle term of "
5592 /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */
5594 {
5597 }
5599 /* arg1 can't be a prvalue result of the conditional
5600 expression, since it needs to be materialized for the
5601 conversion to bool, so treat it as an xvalue in arg2. */
5606 else
5608 }
5610 /* If something has already gone wrong, just pass that fact up the
5611 tree. */
5617 conversion_obstack_sentinel cos;
5624 {
5627 /* If arg1 is another cond_expr choosing between -1 and 0,
5628 then we can use its comparison. It may help to avoid
5629 additional comparison, produce more accurate diagnostics
5630 and enables folding. */
5640 /* force_rvalue can return error_mark on valid arguments. */
5651 {
5652 /* Rely on the error messages of the scalar version. */
5661 {
5669 }
5673 /* We could pass complain & tf_warning to unsafe_conversion_p,
5674 but the warnings (like Wsign-conversion) have already been
5675 given by the scalar build_conditional_expr_1. We still check
5676 unsafe_conversion_p to forbid truncating long long -> float. */
5678 {
5683 }
5685 {
5690 }
5700 }
5704 {
5710 {
5714 {
5720 }
5722 {
5728 }
5731 }
5732 }
5740 {
5743 "incompatible vector types in conditional expression: "
5747 }
5750 {
5753 }
5755 }
5757 /* [expr.cond]
5759 The first expression is implicitly converted to bool (clause
5760 _conv_). */
5762 LOOKUP_NORMAL);
5777 {
5778 semantic_result_type
5781 {
5792 && cp_compare_floating_point_conversion_ranks
5799 }
5801 {
5804 }
5806 {
5809 }
5810 }
5812 /* [expr.cond]
5814 If either the second or the third operand has type (possibly
5815 cv-qualified) void, then the lvalue-to-rvalue (_conv.lval_),
5816 array-to-pointer (_conv.array_), and function-to-pointer
5817 (_conv.func_) standard conversions are performed on the second
5818 and third operands. */
5820 {
5821 /* 'void' won't help in resolving an overloaded expression on the
5822 other side, so require it to resolve by itself. */
5824 {
5827 }
5829 {
5832 }
5834 /* [expr.cond]
5836 One of the following shall hold:
5838 --The second or the third operand (but not both) is a
5839 throw-expression (_except.throw_); the result is of the type
5840 and value category of the other.
5842 --Both the second and the third operands have type void; the
5843 result is of type void and is a prvalue. */
5846 {
5849 }
5852 {
5855 }
5857 {
5860 }
5861 else
5862 {
5864 {
5867 "second operand to the conditional operator "
5868 "is of type %<void%>, but the third operand is "
5870 else
5872 "third operand to the conditional operator "
5873 "is of type %<void%>, but the second operand is "
5875 }
5877 }
5880 }
5881 /* [expr.cond]
5883 Otherwise, if the second and third operand have different types,
5884 and either has (possibly cv-qualified) class type, or if both are
5885 glvalues of the same value category and the same type except for
5886 cv-qualification, an attempt is made to convert each of those operands
5887 to the type of the other. */
5891 arg3_type)
5894 {
5902 /* [expr.cond]
5904 If both can be converted, or one can be converted but the
5905 conversion is ambiguous, the program is ill-formed. If
5906 neither can be converted, the operands are left unchanged and
5907 further checking is performed as described below. If exactly
5908 one conversion is possible, that conversion is applied to the
5909 chosen operand and the converted operand is used in place of
5910 the original operand for the remainder of this section. */
5915 {
5917 {
5925 else
5927 }
5929 }
5931 {
5935 /* Even if CONV2 is a valid conversion, the result of the
5936 conversion may be invalid. For example, if ARG3 has type
5937 "volatile X", and X does not have a copy constructor
5938 accepting a "volatile X&", then even if ARG2 can be
5939 converted to X, the conversion will fail. */
5943 }
5945 {
5952 }
5957 /* If, after the conversion, both operands have class type,
5958 treat the cv-qualification of both operands as if it were the
5959 union of the cv-qualification of the operands.
5961 The standard is not clear about what to do in this
5962 circumstance. For example, if the first operand has type
5963 "const X" and the second operand has a user-defined
5964 conversion to "volatile X", what is the type of the second
5965 operand after this step? Making it be "const X" (matching
5966 the first operand) seems wrong, as that discards the
5967 qualification without actually performing a copy. Leaving it
5968 as "volatile X" seems wrong as that will result in the
5969 conditional expression failing altogether, even though,
5970 according to this step, the one operand could be converted to
5971 the type of the other. */
5979 }
5981 /* [expr.cond]
5983 If the second and third operands are glvalues of the same value
5984 category and have the same type, the result is of that type and
5985 value category. */
5989 {
5992 }
5994 /* [expr.cond]
5996 Otherwise, the result is an rvalue. If the second and third
5997 operand do not have the same type, and either has (possibly
5998 cv-qualified) class type, overload resolution is used to
5999 determine the conversions (if any) to be applied to the operands
6000 (_over.match.oper_, _over.built_). */
6004 {
6005 releasing_vec args;
6009 /* Rearrange the arguments so that add_builtin_candidate only has
6010 to know about two args. In build_builtin_candidate, the
6011 arguments are unscrambled. */
6016 COND_EXPR,
6017 NOP_EXPR,
6019 args,
6022 /* [expr.cond]
6024 If the overload resolution fails, the program is
6025 ill-formed. */
6028 {
6033 }
6036 {
6038 {
6039 auto_diagnostic_group d;
6042 }
6044 }
6046 /* [expr.cond]
6048 Otherwise, the conversions thus determined are applied, and
6049 the converted operands are used in place of the original
6050 operands for the remainder of this section. */
6059 }
6061 /* [expr.cond]
6063 Lvalue-to-rvalue (_conv.lval_), array-to-pointer (_conv.array_),
6064 and function-to-pointer (_conv.func_) standard conversions are
6065 performed on the second and third operands.
6067 We need to force the lvalue-to-rvalue conversion here for class types,
6068 so we get TARGET_EXPRs; trying to deal with a COND_EXPR of class rvalues
6069 that isn't wrapped with a TARGET_EXPR plays havoc with exception
6070 regions. */
6083 /* [expr.cond]
6085 After those conversions, one of the following shall hold:
6087 --The second and third operands have the same type; the result is of
6088 that type. */
6091 /* [expr.cond]
6093 --The second and third operands have arithmetic or enumeration
6094 type; the usual arithmetic conversions are performed to bring
6095 them to a common type, and the result is of that type. */
6100 {
6101 /* A conditional expression between a floating-point
6102 type and an integer type should convert the integer type to
6103 the evaluation format of the floating-point type, with
6104 possible excess precision. */
6107 tree eptype;
6110 {
6113 semantic_result_type
6115 }
6118 {
6121 semantic_result_type
6123 }
6125 eptype3);
6127 {
6138 && cp_compare_floating_point_conversion_ranks
6145 }
6147 {
6158 && cp_compare_floating_point_conversion_ranks
6165 }
6169 "implicit conversion from %qH to %qI to "
6171 loc);
6175 {
6182 /* Two enumerators from the same enumeration can have different
6188 }
6190 && warn_deprecated_enum_float_conv
6195 {
6198 "conditional expression between enumeration type "
6201 else
6203 "conditional expression between floating-point "
6206 }
6213 {
6215 {
6217 ? OPT_Wenum_conversion
6221 }
6222 }
6226 }
6227 /* [expr.cond]
6229 --The second and third operands have pointer type, or one has
6230 pointer type and the other is a null pointer constant; pointer
6231 conversions (_conv.ptr_) and qualification conversions
6232 (_conv.qual_) are performed to bring them to their composite
6233 pointer type (_expr.rel_). The result is of the composite
6234 pointer type.
6236 --The second and third operands have pointer to member type, or
6237 one has pointer to member type and the other is a null pointer
6238 constant; pointer to member conversions (_conv.mem_) and
6239 qualification conversions (_conv.qual_) are performed to bring
6240 them to a common type, whose cv-qualification shall match the
6241 cv-qualification of either the second or the third operand.
6242 The result is of the common type. */
6250 {
6254 complain);
6259 }
6262 {
6267 }
6272 valid_operands:
6274 {
6275 /* Let lvalue_kind know this was a glvalue. */
6278 }
6282 /* If the ARG2 and ARG3 are the same and don't have side-effects,
6283 warn here, because the COND_EXPR will be turned into ARG2. */
6287 OEP_ADDRESS_OF_SAME_FIELD)))
6291 /* We can't use result_type below, as fold might have returned a
6292 throw_expr. */
6295 {
6296 /* Expand both sides into the same slot, hopefully the target of
6297 the ?: expression. We used to check for TARGET_EXPRs here,
6298 but now we sometimes wrap them in NOP_EXPRs so the test would
6299 fail. */
6301 {
6303 /* Tell gimplify_modify_expr_rhs not to strip this in
6304 assignment context: we want both arms to initialize
6305 the same temporary. */
6307 }
6308 /* If this expression is an rvalue, but might be mistaken for an
6309 lvalue, we must add a NON_LVALUE_EXPR. */
6313 result);
6314 }
6315 else
6316 {
6319 }
6322 }
6324 /* OPERAND is an operand to an expression. Perform necessary steps
6325 required before using it. If OPERAND is NULL_TREE, NULL_TREE is
6326 returned. */
6328 static tree
6330 {
6332 {
6335 /* Make sure the template type is instantiated now. */
6337 }
6340 }
6342 /* True iff CONV represents a conversion sequence which no other can be better
6343 than under [over.ics.rank]: in other words, a "conversion" to the exact same
6344 type (including binding to a reference to the same type). This is stronger
6345 than the standard's "identity" category, which also includes reference
6346 bindings that add cv-qualifiers or change rvalueness. */
6348 static bool
6350 {
6354 {
6360 }
6362 /* Brace elision is imperfect. */
6365 }
6367 /* True if CAND represents a perfect match, i.e. all perfect conversions, so no
6368 other candidate can be a better match. Since the template/non-template
6369 tiebreaker comes immediately after the conversion comparison in
6370 [over.match.best], a perfect non-template candidate is better than all
6371 templates. */
6373 static bool
6375 {
6378 /* CWG1402 makes an implicitly deleted move op worse than other
6379 candidates. */
6391 }
6393 /* True iff one of CAND's argument conversions is missing. */
6395 static bool
6397 {
6399 {
6404 {
6405 /* We don't know whether this conversion is outright invalid or
6406 just bad, so conservatively assume it's missing. */
6409 }
6410 }
6412 }
6414 /* Add each of the viable functions in FNS (a FUNCTION_DECL or
6415 OVERLOAD) to the CANDIDATES, returning an updated list of
6416 CANDIDATES. The ARGS are the arguments provided to the call;
6417 if FIRST_ARG is non-null it is the implicit object argument,
6418 otherwise the first element of ARGS is used if needed. The
6419 EXPLICIT_TARGS are explicit template arguments provided.
6420 TEMPLATE_ONLY is true if only template functions should be
6421 considered. CONVERSION_PATH, ACCESS_PATH, and FLAGS are as for
6422 add_function_candidate. */
6424 static void
6426 tree return_type,
6431 tsubst_flags_t complain)
6432 {
6433 tree ctype;
6437 unification_kind_t strict;
6443 /* Precalculate special handling of constructors and conversion ops. */
6446 {
6450 /* We're doing return_type(x). */
6452 else
6453 /* We're doing x.operator return_type(). */
6455 /* [over.match.funcs] For conversion functions, the function
6456 is considered to be a member of the class of the implicit
6457 object argument for the purpose of defining the type of
6458 the implicit object parameter. */
6460 }
6461 else
6462 {
6464 {
6466 /* For list-initialization we consider explicit constructors
6467 and complain if one is chosen. */
6468 check_converting
6471 }
6474 }
6476 /* P2468: Check if operator== is a rewrite target with first operand
6477 (*args)[0]; for now just do the lookups. */
6480 {
6483 {
6488 else
6490 }
6491 else
6492 {
6499 }
6500 }
6504 else
6505 /* Delay creating the implicit this parameter until it is needed. */
6509 /* If there's a non-template perfect match, we don't need to consider
6510 templates. So check non-templates first. This optimization is only
6511 really needed for the defaulted copy constructor of tuple and the like
6512 (96926), but it seems like we might as well enable it more generally. */
6520 /* During overload resolution, we first consider each function under the
6521 assumption that we'll eventually find a strictly viable candidate.
6522 This allows us to circumvent our defacto behavior when checking
6523 argument conversions and shortcut consideration of the candidate
6524 upon encountering the first bad conversion. If this assumption
6525 turns out to be false, and all candidates end up being non-strictly
6526 viable, then we reconsider such candidates under the defacto behavior.
6527 This trick is important for pruning member function overloads according
6528 to their const/ref-qualifiers (since all 'this' conversions are at
6529 worst bad) without breaking -fpermissive. */
6533 again:
6535 {
6549 {
6550 /* Figure out where the object arg comes from. If this
6551 function is a non-static member and we didn't get an
6552 implicit object argument, move it out of args. */
6554 {
6556 tree arg;
6563 }
6567 }
6569 /* Don't bother reversing an operator with two identical parameters. */
6571 {
6576 }
6578 /* When considering reversed operator==, if there's a corresponding
6579 operator!= in the same scope, it's not a rewrite target. */
6581 {
6587 /* ??? This kludge excludes inline namespace members for the H
6588 test in spaceship-eq15.C, but I don't see why we would want
6591 {
6594 }
6597 }
6600 {
6602 fn,
6603 ctype,
6604 explicit_targs,
6605 fn_first_arg,
6606 fn_args,
6607 return_type,
6608 access_path,
6609 conversion_path,
6610 flags,
6611 strict,
6612 shortcut_bad_convs,
6613 complain))
6615 }
6616 else
6617 {
6619 fn,
6620 ctype,
6621 fn_first_arg,
6622 fn_args,
6623 access_path,
6624 conversion_path,
6625 flags,
6626 NULL,
6627 shortcut_bad_convs,
6628 complain);
6631 }
6638 && shortcut_bad_convs
6640 {
6641 /* This candidate has been tentatively marked non-strictly viable,
6642 and we didn't compute all argument conversions for it (having
6643 stopped at the first bad conversion). Add the function to BAD_FNS
6644 to fully reconsider later if we don't find any strictly viable
6645 candidates. */
6647 {
6650 }
6651 else
6652 /* But if we're in a SFINAE context, just mark this candidate as
6653 unviable outright and avoid potentially reconsidering it.
6654 This is safe to do because in a SFINAE context, performing a bad
6655 conversion is always an error (even with -fpermissive), so a
6656 non-strictly viable candidate is effectively unviable anyway. */
6658 }
6659 }
6661 {
6664 }
6666 && !seen_strictly_viable
6667 && shortcut_bad_convs
6669 {
6670 /* None of the candidates are strictly viable, so consider again those
6671 functions in BAD_FNS, this time without shortcutting bad conversions
6672 so that all their argument conversions are computed. */
6677 }
6678 }
6680 /* Returns 1 if P0145R2 says that the LHS of operator CODE is evaluated first,
6681 -1 if the RHS is evaluated first, or 0 if the order is unspecified. */
6683 static int
6685 {
6687 {
6688 // 5. b @= a
6692 // 6. a[b]
6696 // 1. a.b
6697 // Not overloadable (yet).
6698 // 2. a->b
6699 // Only one argument.
6700 // 3. a->*b
6702 // 7. a << b
6704 // 8. a >> b
6706 // a && b
6707 // Predates P0145R3.
6709 // a || b
6710 // Predates P0145R3.
6712 // a , b
6713 // Predates P0145R3.
6719 }
6720 }
6722 /* Subroutine of build_new_op: Add to CANDIDATES all candidates for the
6723 operator indicated by CODE/CODE2. This function calls itself recursively to
6724 handle C++20 rewritten comparison operator candidates.
6726 LOOKUPS, if non-NULL, is the set of pertinent namespace-scope operator
6727 overloads to consider. This parameter is used when instantiating a
6728 dependent operator expression and has the same structure as
6729 DEPENDENT_OPERATOR_TYPE_SAVED_LOOKUPS. */
6731 static tree
6736 {
6741 /* LOOKUP_REWRITTEN is set when we're looking for the == or <=> operator to
6742 rewrite from, and also when we're looking for the e.g. < operator to use
6743 on the result of <=>. In the latter case, we don't want the flag set in
6744 the candidate, we just want to suppress looking for rewrites. */
6751 {
6752 /* =, ->, [], () must be non-static member functions. */
6756 /* FALLTHRU */
6764 }
6766 /* Add namespace-scope operators to the list of functions to
6767 consider. */
6769 {
6770 tree fns;
6773 /* If LOOKUPS is non-NULL, then we're instantiating a dependent operator
6774 expression, and LOOKUPS is the result of stage 1 name lookup. */
6777 else
6783 }
6785 /* Add class-member operators to the candidate set. */
6790 {
6795 {
6797 {
6808 /* Release the vec if we didn't add a candidate that uses it. */
6811 {
6814 }
6816 }
6817 else
6824 }
6825 }
6826 /* Per [over.match.oper]3.2, if no operand has a class type, then
6827 only non-member functions that have type T1 or reference to
6828 cv-qualified-opt T1 for the first argument, if the first argument
6829 has an enumeration type, or T2 or reference to cv-qualified-opt
6830 T2 for the second argument, if the second argument has an
6831 enumeration type. Filter out those that don't match. */
6833 {
6837 {
6845 {
6852 && (same_type_ignoring_top_level_qualifiers_p
6857 }
6859 /* No argument has an appropriate type, so remove this
6860 candidate function from the list. */
6862 {
6865 }
6866 }
6867 }
6870 {
6871 /* The standard says to rewrite built-in candidates, too,
6872 but there's no point. */
6876 /* Maybe add C++20 rewritten comparison candidates. */
6882 {
6897 }
6900 {
6903 /* Add rewritten candidates in same order. */
6909 /* Add rewritten candidates in reverse order. */
6917 /* Release the vec if we didn't add a candidate that uses it. */
6920 {
6923 }
6925 }
6926 }
6929 }
6931 tree
6935 {
6937 releasing_vec arglist;
6953 conversion_obstack_sentinel cos;
6957 {
6960 }
6968 {
6973 /* Use build_operator_new_call and build_op_delete_call instead. */
6977 /* Use build_op_call instead. */
6984 /* These are saved for the sake of warn_logical_operator. */
6994 /* These are saved for the sake of maybe_warn_bool_compare. */
7001 }
7007 /* Use build_conditional_expr instead. */
7014 {
7017 }
7031 {
7034 /* For these, the built-in candidates set is empty
7035 [over.match.oper]/3. We don't want non-strict matches
7036 because exact matches are always possible with built-in
7037 operators. The built-in candidate set for COMPONENT_REF
7038 would be empty too, but since there are no such built-in
7039 operators, we accept non-strict matches for them. */
7046 }
7050 {
7052 {
7055 /* Don't try anything fancy if we're not allowed to produce
7056 errors. */
7060 /* Look for an `operator++ (int)'. Pre-1985 C++ didn't
7061 distinguish between prefix and postfix ++ and
7062 operator++() was used for both, so we allow this with
7063 -fpermissive. */
7064 else
7065 {
7072 }
7079 else
7085 /* The caller will deal with these. */
7096 {
7097 /* If one of the arguments of the operator represents
7098 an invalid use of member function pointer, try to report
7099 a meaningful error ... */
7104 else
7105 {
7106 /* ... Otherwise, report the more generic
7107 "no matching operator found" error */
7108 auto_diagnostic_group d;
7111 }
7112 }
7115 }
7116 }
7117 else
7118 {
7121 {
7123 {
7124 auto_diagnostic_group d;
7127 }
7131 }
7133 {
7139 else
7140 {
7143 /* We'll wrap this call in another one. */
7146 {
7147 /* We swapped these in add_candidate, swap them back now. */
7151 "current function recursively with reversed "
7153 }
7155 }
7160 {
7164 /* Specify evaluation order as per P0145R2. */
7167 {
7178 }
7179 }
7181 /* If this was a C++20 rewritten comparison, adjust the result. */
7183 {
7184 /* FIXME build_min_non_dep_op_overload can't handle rewrites. */
7188 {
7194 ;
7195 /* If a rewritten operator== candidate is selected by
7196 overload resolution for an operator @, its return type
7197 shall be cv bool.... */
7199 {
7201 {
7202 auto_diagnostic_group d;
7208 }
7210 }
7212 /* !(y == x) or !(x == y) */
7217 /* If a rewritten operator<=> candidate is selected by
7218 overload resolution for an operator @, x @ y is
7219 interpreted as 0 @ (y <=> x) if the selected candidate is
7220 a synthesized candidate with reversed order of parameters,
7221 or (x <=> y) @ 0 otherwise, using the selected rewritten
7222 operator<=> candidate. */
7225 /* We're in the build_new_op call below for an outer
7226 reversed call; we don't need to do anything more. */
7233 {
7243 }
7248 }
7249 }
7251 /* In an expression of the form `a[]' where cand->fn
7252 which is operator[] turns out to be a static member function,
7253 `a' is none-the-less evaluated. */
7256 }
7257 else
7258 {
7259 /* Give any warnings we noticed during overload resolution. */
7261 {
7265 }
7267 /* Check for comparison of different enum types. */
7269 {
7287 }
7289 /* "If a built-in candidate is selected by overload resolution, the
7290 operands of class type are converted to the types of the
7291 corresponding parameters of the selected operation function,
7292 except that the second standard conversion sequence of a
7293 user-defined conversion sequence (12.3.3.1.2) is not applied." */
7296 {
7299 }
7302 {
7305 {
7308 }
7309 }
7312 {
7315 {
7318 }
7319 }
7320 }
7321 }
7326 builtin:
7328 {
7343 /* Fall through. */
7356 /* Fall through. */
7391 RO_ARROW_STAR,
7392 complain),
7395 /* The caller will deal with these. */
7403 }
7405 }
7407 /* Build a new call to operator[]. This may change ARGS. */
7409 tree
7412 tsubst_flags_t complain)
7413 {
7431 {
7436 }
7437 else
7441 {
7445 }
7447 conversion_obstack_sentinel cos;
7450 {
7458 }
7460 /* Be strict here because if we choose a bad conversion candidate, the
7461 errors we get won't mention the call context. */
7464 {
7466 {
7467 auto_diagnostic_group d;
7471 }
7473 }
7474 else
7475 {
7478 {
7480 {
7481 auto_diagnostic_group d;
7485 }
7487 }
7491 {
7498 {
7502 /* Specify evaluation order as per P0145R2. */
7504 }
7506 /* In an expression of the form `a[]' where cand->fn
7507 which is operator[] turns out to be a static member function,
7508 `a' is none-the-less evaluated. */
7510 }
7511 else
7513 }
7516 }
7518 /* CALL was returned by some call-building function; extract the actual
7519 CALL_EXPR from any bits that have been tacked on, e.g. by
7520 convert_from_reference. */
7522 tree
7524 {
7533 {
7534 /* C++20 rewritten comparison operators. */
7543 {
7547 else
7549 }
7552 }
7559 }
7561 /* Returns true if FN has two parameters, of which the second has type
7562 size_t. */
7564 static bool
7566 {
7574 }
7576 /* True if T, an allocation function, has std::align_val_t as its second
7577 argument. */
7579 bool
7581 {
7587 }
7589 /* True if T is std::destroying_delete_t. */
7591 static bool
7593 {
7596 }
7598 /* A deallocation function with at least two parameters whose second parameter
7599 type is of type std::destroying_delete_t is a destroying operator delete. A
7600 destroying operator delete shall be a class member function named operator
7601 delete. [ Note: Array deletion cannot use a destroying operator
7602 delete. --end note ] */
7604 tree
7606 {
7612 }
7614 struct dealloc_info
7615 {
7618 tree destroying;
7619 };
7621 /* Returns true iff T, an element of an OVERLOAD chain, is a usual deallocation
7622 function (3.7.4.2 [basic.stc.dynamic.deallocation]). If so, and DI is
7623 non-null, also set *DI. */
7625 static bool
7627 {
7630 /* A template instance is never a usual deallocation function,
7631 regardless of its signature. */
7636 /* A usual deallocation function is a deallocation function whose parameters
7637 after the first are
7638 - optionally, a parameter of type std::destroying_delete_t, then
7639 - optionally, a parameter of type std::size_t, then
7640 - optionally, a parameter of type std::align_val_t. */
7644 {
7647 }
7651 {
7654 }
7657 {
7660 }
7662 }
7664 /* Just return whether FN is a usual deallocation function. */
7666 bool
7668 {
7670 }
7672 /* Build a call to operator delete. This has to be handled very specially,
7673 because the restrictions on what signatures match are different from all
7674 other call instances. For a normal delete, only a delete taking (void *)
7675 or (void *, size_t) is accepted. For a placement delete, only an exact
7676 match with the placement new is accepted.
7678 CODE is either DELETE_EXPR or VEC_DELETE_EXPR.
7679 ADDR is the pointer to be deleted.
7680 SIZE is the size of the memory block to be deleted.
7681 GLOBAL_P is true if the delete-expression should not consider
7682 class-specific delete operators.
7683 PLACEMENT is the corresponding placement new call, or NULL_TREE.
7685 If this call to "operator delete" is being generated as part to
7686 deallocate memory allocated via a new-expression (as per [expr.new]
7687 which requires that if the initialization throws an exception then
7688 we call a deallocation function), then ALLOC_FN is the allocation
7689 function. */
7691 tree
7695 {
7698 dealloc_info di_fn = { };
7710 /* In [class.free]
7712 If the result of the lookup is ambiguous or inaccessible, or if
7713 the lookup selects a placement deallocation function, the
7714 program is ill-formed.
7716 Therefore, we ask lookup_fnfields to complain about ambiguity. */
7717 {
7721 }
7722 else
7728 /* Strip const and volatile from addr. */
7735 {
7736 /* "A declaration of a placement deallocation function matches the
7737 declaration of a placement allocation function if it has the same
7738 number of parameters and, after parameter transformations (8.3.5),
7739 all parameter types except the first are identical."
7741 So we build up the function type we want and ask instantiate_type
7742 to get it for us. */
7753 /* "If the lookup finds the two-parameter form of a usual deallocation
7754 function (3.7.4.2) and that function, considered as a placement
7755 deallocation function, would have been selected as a match for the
7756 allocation function, the program is ill-formed." */
7758 {
7766 /* But if the class has an operator delete (void *), then that is
7767 the usual deallocation function, so we shouldn't complain
7768 about using the operator delete (void *, size_t). */
7771 {
7775 }
7776 /* Before C++14 a two-parameter global deallocation function is
7777 always a placement deallocation function, but warn if
7778 -Wc++14-compat. */
7780 {
7782 {
7783 auto_diagnostic_group d;
7786 }
7788 }
7791 {
7792 auto_diagnostic_group d;
7794 {
7795 /* Only mention C++14 for namespace-scope delete. */
7798 else
7800 "%qD is a usual (non-placement) deallocation "
7802 }
7803 }
7804 else
7806 ok:;
7807 }
7808 }
7809 else
7810 /* "Any non-placement deallocation function matches a non-placement
7811 allocation function. If the lookup finds a single matching
7812 deallocation function, that function will be called; otherwise, no
7813 deallocation function will be called." */
7815 {
7816 dealloc_info di_elt;
7818 {
7819 /* If we're called for an EH cleanup in a new-expression, we can't
7820 use a destroying delete; the exception was thrown before the
7821 object was constructed. */
7823 {
7826 }
7829 {
7833 }
7835 /* -- If any of the deallocation functions is a destroying
7836 operator delete, all deallocation functions that are not
7837 destroying operator deletes are eliminated from further
7838 consideration. */
7840 {
7842 {
7845 }
7847 }
7849 /* -- If the type has new-extended alignment, a function with a
7850 parameter of type std::align_val_t is preferred; otherwise a
7851 function without such a parameter is preferred. If exactly one
7852 preferred function is found, that function is selected and the
7853 selection process terminates. If more than one preferred
7854 function is found, all non-preferred functions are eliminated
7855 from further consideration. */
7857 {
7860 {
7862 {
7865 }
7867 }
7868 }
7870 /* -- If the deallocation functions have class scope, the one
7871 without a parameter of type std::size_t is selected. */
7876 /* -- If the type is complete and if, for the second alternative
7877 (delete array) only, the operand is a pointer to a class type
7878 with a non-trivial destructor or a (possibly multi-dimensional)
7879 array thereof, the function with a parameter of type std::size_t
7880 is selected.
7882 -- Otherwise, it is unspecified whether a deallocation function
7883 with a parameter of type std::size_t is selected. */
7884 else
7885 {
7889 /* We need a cookie to determine the array size. */
7891 }
7894 {
7897 }
7898 }
7899 }
7901 /* If we have a matching function, call it. */
7903 {
7906 /* If the FN is a member function, make sure that it is
7907 accessible. */
7910 complain);
7912 /* Core issue 901: It's ok to new a type with deleted delete. */
7916 tree ret;
7918 {
7919 /* The placement args might not be suitable for overload
7920 resolution at this point, so build the call directly. */
7930 }
7931 else
7932 {
7935 {
7936 /* Strip const and volatile from addr but retain the type of the
7937 object. */
7944 complain);
7945 }
7947 releasing_vec args;
7954 {
7957 }
7959 }
7961 /* Set this flag for all callers of this function. In addition to
7962 delete-expressions, this is called for deallocating coroutine state;
7963 treat that as an implicit delete-expression. This is also called for
7964 the delete if the constructor throws in a new-expression, and for a
7965 deleting destructor (which implements a delete-expression). */
7966 /* But leave this flag off for destroying delete to avoid wrong
7967 assumptions in the optimizers. */
7973 }
7975 /* If there's only a destroying delete that we can't use because the
7976 object isn't constructed yet, and we used global new, use global
7977 delete as well. */
7983 /* [expr.new]
7985 If no unambiguous matching deallocation function can be found,
7986 propagating the exception does not cause the object's memory to
7987 be freed. */
7989 {
7992 {
7995 alloc_fn);
7998 "delete %qD cannot be used to release the allocated memory"
7999 " if the initialization throws because the object is not "
8001 }
8003 }
8009 }
8011 /* Issue diagnostics about a disallowed access of DECL, using DIAG_DECL
8012 in the diagnostics.
8014 If ISSUE_ERROR is true, then issue an error about the access, followed
8015 by a note showing the declaration. Otherwise, just show the note.
8017 DIAG_DECL and DIAG_LOCATION will almost always be the same.
8018 DIAG_LOCATION is just another DECL. NO_ACCESS_REASON is an optional
8019 parameter used to specify why DECL wasn't accessible (e.g. ak_private
8020 would be because DECL was private). If not using NO_ACCESS_REASON,
8021 then it must be ak_none, and the access failure reason will be
8022 figured out by looking at the protection of DECL. */
8024 void
8027 {
8028 /* If we have not already figured out why DECL is inaccessible... */
8030 {
8031 /* Examine the access of DECL to find out why. */
8036 }
8038 /* Now generate an error message depending on calculated access. */
8040 {
8044 }
8046 {
8050 }
8051 /* Couldn't figure out why DECL is inaccesible, so just say it's
8052 inaccessible. */
8053 else
8054 {
8058 }
8059 }
8061 /* Initialize a temporary of type TYPE with EXPR. The FLAGS are a
8062 bitwise or of LOOKUP_* values. If any errors are warnings are
8063 generated, set *DIAGNOSTIC_FN to "error" or "warning",
8064 respectively. If no diagnostics are generated, set *DIAGNOSTIC_FN
8065 to NULL. */
8067 static tree
8070 {
8075 /* If the source is a packed field, calling the copy constructor will require
8076 binding the field to the reference parameter to the copy constructor, and
8077 we'll end up with an infinite loop. If we can use a bitwise copy, then
8078 do that now. */
8084 /* In decltype, we might have decided not to wrap this call in a TARGET_EXPR.
8085 But it turns out to be a subexpression, so perform temporary
8086 materialization now. */
8101 }
8103 /* Get any location for EXPR, falling back to input_location.
8105 If the result is in a system header and is the virtual location for
8106 a token coming from the expansion of a macro, unwind it to the
8107 location of the expansion point of the macro (e.g. to avoid the
8108 diagnostic being suppressed for expansions of NULL where "NULL" is
8109 in a system header). */
8111 static location_t
8113 {
8117 }
8119 /* Perform warnings about peculiar, but valid, conversions from/to NULL.
8120 Also handle a subset of zero as null warnings.
8121 EXPR is implicitly converted to type TOTYPE.
8122 FN and ARGNUM are used for diagnostics. */
8124 static void
8126 {
8127 /* Issue warnings about peculiar, but valid, uses of NULL. */
8131 {
8134 {
8135 auto_diagnostic_group d;
8141 }
8142 else
8145 }
8147 /* Issue warnings if "false" is converted to a NULL pointer */
8150 {
8153 {
8154 auto_diagnostic_group d;
8156 "converting %<false%> to pointer type for argument "
8160 }
8161 else
8164 }
8165 /* Handle zero as null pointer warnings for cases other
8166 than EQ_EXPR and NE_EXPR */
8169 {
8172 }
8173 }
8175 /* We gave a diagnostic during a conversion. If this was in the second
8176 standard conversion sequence of a user-defined conversion sequence, say
8177 which user-defined conversion. */
8179 static void
8181 {
8185 {
8189 }
8190 }
8192 /* Locate the parameter with the given index within FNDECL.
8193 ARGNUM is zero based, -1 indicates the `this' argument of a method.
8194 Return the location of the FNDECL itself if there are problems. */
8196 location_t
8198 {
8199 /* The locations of implicitly-declared functions are likely to be
8200 more meaningful than those of their parameters. */
8205 tree param;
8207 /* Locate param by index within DECL_ARGUMENTS (fndecl). */
8211 ;
8213 /* If something went wrong (e.g. if we have a builtin and thus no arguments),
8214 return the location of FNDECL. */
8219 }
8221 /* If FNDECL is non-NULL, issue a note highlighting ARGNUM
8222 within its declaration (or the fndecl itself if something went
8223 wrong). */
8225 void
8227 {
8231 }
8233 /* Maybe warn about C++20 Conversions to arrays of unknown bound. C is
8234 the conversion, EXPR is the expression we're converting. */
8236 static void
8238 {
8251 "conversions to arrays of unknown bound "
8253 }
8255 /* We call this recursively in convert_like_internal. */
8257 tsubst_flags_t);
8259 /* Perform the conversions in CONVS on the expression EXPR. FN and
8260 ARGNUM are used for diagnostics. ARGNUM is zero based, -1
8261 indicates the `this' argument of a method. INNER is nonzero when
8262 being called to continue a conversion chain. It is negative when a
8263 reference binding will be applied, positive otherwise. If
8264 ISSUE_CONVERSION_WARNINGS is true, warnings about suspicious
8265 conversions will be emitted if appropriate. If C_CAST_P is true,
8266 this conversion is coming from a C-style cast; in that case,
8267 conversions to inaccessible bases are permitted. */
8269 static tree
8273 {
8275 diagnostic_t diag_kind;
8291 {
8295 /* Give a helpful error if this is bad because of excess braces. */
8300 {
8306 }
8308 /* Give a helpful error if this is bad because a conversion to bool
8309 from std::nullptr_t requires direct-initialization. */
8321 totype))
8322 {
8339 }
8342 {
8344 {
8345 auto_diagnostic_group d;
8348 totype);
8354 complain);
8355 }
8357 {
8361 complain);
8365 }
8370 complain);
8373 }
8375 {
8381 }
8385 complain);
8386 else
8391 }
8397 {
8399 {
8403 /* We chose the surrogate function from add_conv_candidate, now we
8404 actually need to build the conversion. */
8410 /* When converting from an init list we consider explicit
8411 constructors, but actually trying to call one is an error. */
8414 /* Unless this is for direct-list-initialization. */
8416 /* And in C++98 a default constructor can't be explicit. */
8418 {
8424 {
8425 auto_diagnostic_group d;
8429 {
8431 convfn);
8434 }
8435 }
8436 else
8437 {
8438 auto_diagnostic_group d;
8442 convfn);
8443 }
8444 }
8446 /* If we're initializing from {}, it's value-initialization. */
8451 {
8458 {
8461 }
8463 }
8465 /* We don't know here whether EXPR is being used as an lvalue or
8466 rvalue, but we know it's read. */
8469 /* Pass LOOKUP_NO_CONVERSION so rvalue/base handling knows not to allow
8470 any more UDCs. */
8472 complain);
8474 /* If this is a constructor or a function returning an aggr type,
8475 we need to build up a TARGET_EXPR. */
8477 {
8480 /* Remember that this was list-initialization. */
8483 }
8486 }
8489 {
8495 else
8497 }
8508 /* If __null has been converted to an integer type, we do not want to
8509 continue to warn about uses of EXPR as an integer, rather than as a
8510 pointer. */
8514 /* We leave bad_p off ck_ambig because overload resolution considers
8515 it valid, it just fails when we try to perform it. So we need to
8516 check complain here, too. */
8518 {
8519 /* Call build_user_type_conversion again for the error. */
8525 }
8529 {
8530 /* Conversion to std::initializer_list<T>. */
8533 tree array;
8536 {
8537 elttype = cp_build_qualified_type
8543 }
8545 {
8550 /* Convert all the elements. */
8552 {
8565 }
8566 /* Build up the array. */
8567 elttype = cp_build_qualified_type
8571 /* This is dubious now, should be blessed by P2752. */
8573 /* Take the address explicitly rather than via decay_conversion
8574 to avoid the error about taking the address of a temporary. */
8576 }
8577 else
8584 /* Build up the initializer_list object. Note: fail gracefully
8585 if the object cannot be completed because, for example, no
8586 definition is provided (c++/80956). */
8597 }
8601 {
8610 }
8613 complain);
8620 };
8630 {
8634 {
8636 {
8637 auto_diagnostic_group d;
8640 }
8642 }
8647 /* Don't introduce copies when passing arguments along to the inherited
8648 constructor. */
8650 && flag_new_inheriting_ctors
8656 /* Copy-list-initialization doesn't actually involve a copy. */
8659 /* Fall through. */
8662 {
8663 /* We are going to bind a reference directly to a base-class
8664 subobject of EXPR. */
8665 /* Build an expression for `*((base*) &expr)'. */
8669 }
8671 /* Copy-initialization where the cv-unqualified version of the source
8672 type is the same class as, or a derived class of, the class of the
8673 destination [is treated as direct-initialization]. [dcl.init] */
8675 /* This conversion is being done in the context of a user-defined
8676 conversion (i.e. the second step of copy-initialization), so
8677 don't allow any more. */
8680 /* We might be performing a conversion of the argument
8681 to the user-defined conversion, i.e., not a conversion of the
8682 result of the user-defined conversion. In which case we skip
8683 explicit constructors. */
8688 {
8689 auto_diagnostic_group d;
8692 }
8697 {
8700 /* direct_reference_binding might have inserted a ck_qual under
8701 this ck_ref_bind for the benefit of conversion sequence ranking.
8702 Ignore the conversion; we'll create our own below. */
8705 {
8708 /* Strip the cast created by the ck_qual; cp_build_addr_expr
8709 below expects an lvalue. */
8711 }
8714 {
8716 auto_diagnostic_group d;
8723 {
8726 {
8731 }
8738 extype);
8739 }
8741 {
8742 /* If we're converting from T[] to T[N], don't talk
8743 about discarding qualifiers. (Converting from T[N] to
8744 T[] is allowed by P0388R4.) */
8751 else
8754 }
8755 else
8761 }
8765 /* If necessary, create a temporary.
8767 VA_ARG_EXPR and CONSTRUCTOR expressions are special cases
8768 that need temporaries, even when their types are reference
8769 compatible with the type of reference being bound, so the
8770 upcoming call to cp_build_addr_expr doesn't fail. */
8774 {
8775 /* Otherwise, a temporary of type "cv1 T1" is created and
8776 initialized from the initializer expression using the rules
8777 for a non-reference copy-initialization (8.5). */
8785 {
8786 /* If the reference is volatile or non-const, we
8787 cannot create a temporary. */
8789 {
8796 else
8799 }
8801 }
8802 /* If the source is a packed field, and we must use a copy
8803 constructor, then building the target expr will require
8804 binding the field to the reference parameter to the
8805 copy constructor, and we'll end up with an infinite
8806 loop. If we can use a bitwise copy, then we'll be
8807 OK. */
8811 {
8815 }
8817 {
8820 }
8822 /* Creating &TARGET_EXPR<> in a template would break when
8823 tsubsting the expression, so use an IMPLICIT_CONV_EXPR
8824 instead. This can happen even when there's no class
8825 involved, e.g., when converting an integer to a reference
8826 type. */
8830 }
8832 /* Take the address of the thing to which we will bind the
8833 reference. */
8838 /* Convert it to a pointer to the type referred to by the
8839 reference. This will adjust the pointer if a derived to
8840 base conversion is being performed. */
8843 /* Convert the pointer to the desired reference type. */
8845 }
8851 /* ??? Should the address of a transaction-safe pointer point to the TM
8852 clone, and this conversion look up the primary function? */
8856 /* Warn about deprecated conversion if appropriate. */
8858 {
8861 }
8876 }
8886 else
8887 {
8891 }
8894 }
8896 /* Return true if converting FROM to TO is unsafe in a template. */
8898 static bool
8900 {
8901 /* Converting classes involves TARGET_EXPR. */
8905 /* Converting real to integer produces FIX_TRUNC_EXPR which tsubst
8906 doesn't handle. */
8910 /* Converting integer to real isn't a trivial conversion, either. */
8915 }
8917 /* Wrapper for convert_like_internal that handles creating
8918 IMPLICIT_CONV_EXPR. */
8920 static tree
8923 tsubst_flags_t complain)
8924 {
8925 /* Creating &TARGET_EXPR<> in a template breaks when substituting,
8926 and creating a CALL_EXPR in a template breaks in finish_call_expr
8927 so use an IMPLICIT_CONV_EXPR for this conversion. We would have
8928 created such codes e.g. when calling a user-defined conversion
8929 function. */
8934 {
8940 /* Do the normal processing to give the bad_p errors. But we still
8941 need to return the IMPLICIT_CONV_EXPR, unless we're returning
8942 error_mark_node. */
8943 }
8950 }
8952 /* Convenience wrapper for convert_like. */
8956 {
8960 }
8962 /* Convenience wrapper for convert_like. */
8966 tsubst_flags_t complain)
8967 {
8971 }
8973 /* ARG is being passed to a varargs function. Perform any conversions
8974 required. Return the converted value. */
8976 tree
8978 {
8982 /* [expr.call]
8984 If the argument has integral or enumeration type that is subject
8985 to the integral promotions (_conv.prom_), or a floating-point
8986 type that is subject to the floating-point promotion
8987 (_conv.fpprom_), the value of the argument is converted to the
8988 promoted type before the call. */
8994 {
8998 "implicit conversion from %qH to %qI when passing "
9005 }
9007 {
9010 {
9013 }
9014 else
9016 }
9018 {
9020 {
9022 complain);
9029 arg_type,
9033 }
9034 else
9036 }
9037 else
9038 /* [expr.call]
9040 The lvalue-to-rvalue, array-to-pointer, and function-to-pointer
9041 standard conversions are performed. */
9048 /* In a template (or ill-formed code), we can have an incomplete type
9049 even after require_complete_type, in which case we don't know
9050 whether it has trivial copy or not. */
9053 {
9054 /* [expr.call] 5.2.2/7:
9055 Passing a potentially-evaluated argument of class type (Clause 9)
9056 with a non-trivial copy constructor or a non-trivial destructor
9057 with no corresponding parameter is conditionally-supported, with
9058 implementation-defined semantics.
9060 We support it as pass-by-invisible-reference, just like a normal
9061 value parameter.
9063 If the call appears in the context of a sizeof expression,
9064 it is not potentially-evaluated. */
9067 {
9071 "passing objects of non-trivially-copyable "
9073 arg_type);
9075 }
9076 /* Build up a real lvalue-to-rvalue conversion in case the
9077 copy constructor is trivial but not callable. */
9081 }
9084 }
9086 /* va_arg (EXPR, TYPE) is a builtin. Make sure it is not abused. */
9088 tree
9090 {
9092 {
9096 }
9106 {
9109 }
9113 {
9114 /* conditionally-supported behavior [expr.call] 5.2.2/7. Let's treat
9115 it as pass by invisible reference. */
9117 "receiving objects of non-trivially-copyable type %q#T "
9123 }
9127 /* Wrap the VA_ARG_EXPR in a TARGET_EXPR now so other code doesn't need to
9128 know how to handle it. */
9131 }
9133 /* TYPE has been given to va_arg. Apply the default conversions which
9134 would have happened when passed via ellipsis. Return the promoted
9135 type, or the passed type if there is no change. */
9137 tree
9139 {
9140 tree promote;
9142 /* Perform the array-to-pointer and function-to-pointer
9143 conversions. */
9151 }
9153 /* ARG is a default argument expression being passed to a parameter of
9154 the indicated TYPE, which is a parameter to FN. PARMNUM is the
9155 zero-based argument number. Do any required conversions. Return
9156 the converted value. */
9159 void
9163 void
9167 tree
9169 tsubst_flags_t complain)
9170 {
9172 tree t;
9174 /* See through clones. */
9176 /* And inheriting ctors. */
9180 /* Detect recursion. */
9183 {
9187 }
9189 /* If the ARG is an unparsed default argument expression, the
9190 conversion cannot be performed. */
9192 {
9197 }
9204 /* Due to:
9206 [dcl.fct.default]
9208 The names in the expression are bound, and the semantic
9209 constraints are checked, at the point where the default
9210 expressions appears.
9212 we must not perform access checks here. */
9214 /* We must make a copy of ARG, in case subsequent processing
9215 alters any part of it. */
9220 complain);
9227 }
9229 /* Returns the type which will really be used for passing an argument of
9230 type TYPE. */
9232 tree
9234 {
9235 /* Pass classes with copy ctors by invisible reference. */
9245 }
9247 /* Actually perform the appropriate conversion. */
9249 tree
9251 {
9252 tree bitfield_type;
9254 /* If VAL is a bitfield, then -- since it has already been converted
9255 to TYPE -- it cannot have a precision greater than TYPE.
9257 If it has a smaller precision, we must widen it here. For
9258 example, passing "int f:3;" to a function expecting an "int" will
9259 not result in any conversion before this point.
9261 If the precision is the same we must not risk widening. For
9262 example, the COMPONENT_REF for a 32-bit "long long" bitfield will
9263 often have type "int", even though the C++ type for the field is
9264 "long long". If the value is being passed to a function
9265 expecting an "int", then no conversions will be required. But,
9266 if we call convert_bitfield_to_declared_type, the bitfield will
9267 be converted to "long long". */
9274 ;
9275 /* Pass classes with copy ctors by invisible reference. */
9284 {
9286 {
9294 "argument of function call might be a candidate "
9296 }
9298 }
9304 }
9306 /* Returns non-zero iff FN is a function with magic varargs, i.e. ones for
9307 which just decay_conversion or no conversions at all should be done.
9308 This is true for some builtins which don't act like normal functions.
9309 Return 2 if just decay_conversion and removal of excess precision should
9310 be done, 1 if just decay_conversion. Return 3 for special treatment of
9311 the 3rd argument for __builtin_*_overflow_p. */
9313 int
9315 {
9318 {
9341 }
9344 }
9346 /* Returns the decl of the dispatcher function if FN is a function version. */
9348 tree
9350 {
9363 {
9367 }
9372 }
9374 /* fn is a function version dispatcher that is marked used. Mark all the
9375 semantically identical function versions it will dispatch as used. */
9377 void
9379 {
9396 /* All semantically identical versions are chained. Traverse and mark each
9397 one of them as used. */
9400 {
9403 }
9404 }
9406 /* Build a call to "the copy constructor" for the type of A, even if it
9407 wouldn't be selected by normal overload resolution. Used for
9408 diagnostics. */
9410 static tree
9412 {
9422 }
9424 /* Return the base constructor corresponding to COMPLETE_CTOR or NULL_TREE. */
9426 static tree
9428 {
9429 tree clone;
9434 }
9436 /* Try to make EXP suitable to be used as the initializer for a base subobject,
9437 and return whether we were successful. EXP must have already been cleared
9438 by unsafe_copy_elision_p{,_opt}. */
9440 static bool
9442 {
9448 {
9451 {
9453 /* If unsafe_copy_elision_p was false, the arms should match. */
9455 }
9457 }
9459 /* A trivial copy is OK. */
9462 /* unsafe_copy_elision_p_opt must have said this is OK. */
9470 /* The base constructor has more parameters, so we can't just change the
9471 call target. It would be possible to splice in the appropriate
9472 arguments, but probably not worth the complexity. */
9477 }
9479 /* Return 2 if T refers to a base, 1 if a potentially-overlapping field,
9480 neither of which can be used for return by invisible reference. We avoid
9481 doing C++17 mandatory copy elision for either of these cases.
9483 This returns non-zero even if the type of T has no tail padding that other
9484 data could be allocated into, because that depends on the particular ABI.
9485 unsafe_copy_elision_p_opt does consider whether there is padding. */
9487 int
9489 {
9490 /* Check empty bases separately, they don't have fields. */
9494 /* A delegating constructor might be used to initialize a base. */
9509 /* The middle-end will do the right thing for scalar types. */
9516 }
9518 /* True IFF EXP is a prvalue that represents return by invisible reference. */
9520 static bool
9522 {
9523 /* Copy elision only happens with a TARGET_EXPR. */
9527 /* build_compound_expr pushes COMPOUND_EXPR inside TARGET_EXPR. */
9531 {
9532 /* We'll end up copying from each of the arms of the COND_EXPR directly
9533 into the target, so look at them. */
9538 }
9541 }
9543 /* We can't elide a copy from a function returning by value to a
9544 potentially-overlapping subobject, as the callee might clobber tail padding.
9545 Return true iff this could be that case.
9547 Places that use this function (or _opt) to decide to elide a copy should
9548 probably use make_safe_copy_elision instead. */
9550 bool
9552 {
9554 }
9556 /* As above, but for optimization allow more cases that are actually safe. */
9558 static bool
9560 {
9562 /* It's safe to elide the copy for a class with no tail padding. */
9567 }
9569 /* Try to make EXP suitable to be used as the initializer for TARGET,
9570 and return whether we were successful. */
9572 bool
9574 {
9583 }
9585 /* True IFF the result of the conversion C is a prvalue. */
9587 static bool
9589 {
9601 }
9603 /* True iff C is a conversion that binds a reference to a prvalue. */
9605 static bool
9607 {
9614 }
9616 /* True iff EXPR represents a (subobject of a) temporary. */
9618 static bool
9620 {
9624 }
9626 /* True iff C is a conversion that binds a reference to a temporary.
9627 This is a superset of conv_binds_ref_to_prvalue: here we're also
9628 interested in xvalues. */
9630 static bool
9632 {
9638 /* This is the case for
9639 struct Base {};
9640 struct Derived : Base {};
9641 const Base& b(Derived{});
9642 where we bind 'b' to the Base subobject of a temporary object of type
9643 Derived. The subobject is an xvalue; the whole object is a prvalue.
9645 The ck_base doesn't have to be present for cases like X{}.m. */
9652 }
9654 /* Return tristate::TS_TRUE if converting EXPR to a reference type TYPE binds
9655 the reference to a temporary. Return tristate::TS_FALSE if converting
9656 EXPR to a reference type TYPE doesn't bind the reference to a temporary. If
9657 the conversion is invalid or bad, return tristate::TS_UNKNOWN. DIRECT_INIT_P
9658 says whether the conversion should be done in direct- or copy-initialization
9659 context. */
9661 tristate
9663 {
9666 conversion_obstack_sentinel cos;
9676 }
9678 /* Call the trivial destructor for INSTANCE, which can be either an lvalue of
9679 class type or a pointer to class type. If NO_PTR_DEREF is true and
9680 INSTANCE has pointer type, clobber the pointer rather than what it points
9681 to. */
9683 tree
9685 {
9689 {
9690 no_clobber:
9692 }
9696 {
9700 }
9702 /* A trivial destructor should still clobber the object. */
9706 }
9708 /* Return true if in an immediate function context, or an unevaluated operand,
9709 or a default argument/member initializer, or a subexpression of an immediate
9710 invocation. */
9712 bool
9714 {
9718 /* DR 2631: default args and DMI aren't immediately evaluated.
9719 Return true here so immediate_invocation_p returns false. */
9724 }
9726 /* Return true if a call to FN with number of arguments NARGS
9727 is an immediate invocation. */
9729 static bool
9731 {
9735 }
9737 /* Subroutine of the various build_*_call functions. Overload resolution
9738 has chosen a winning candidate CAND; build up a CALL_EXPR accordingly.
9739 ARGS is a TREE_LIST of the unconverted arguments to the call. FLAGS is a
9740 bitmask of various LOOKUP_* flags which apply to the call itself. */
9742 static tree
9744 {
9752 tree val;
9761 /* In a template, there is no need to perform all of the work that
9762 is normally done. We are only interested in the type of the call
9763 expression, i.e., the return type of the function. Any semantic
9764 errors will be deferred until the template is instantiated. */
9766 {
9769 else
9770 /* Otherwise set TREE_USED for the benefit of -Wunused-function.
9771 See PR80598. */
9775 tree callee;
9777 {
9781 }
9782 else
9783 {
9788 }
9795 {
9802 {
9805 }
9806 /* Look through *(const T *)&obj. */
9808 {
9812 {
9817 }
9818 }
9821 obj_arg);
9822 }
9824 }
9826 /* Give any warnings we noticed during overload resolution. */
9828 {
9832 }
9834 /* Core issue 2327: P0135 doesn't say how to handle the case where the
9835 argument to the copy constructor ends up being a prvalue after
9836 conversion. Let's do the normal processing, but pretend we aren't
9837 actually using the copy constructor. */
9846 {
9849 }
9851 /* OK, we're actually calling this inherited constructor; set its deletedness
9852 appropriately. We can get away with doing this here because calling is
9853 the only way to refer to a constructor. */
9856 {
9860 }
9862 /* Make =delete work with SFINAE. */
9864 {
9868 }
9871 {
9872 tree access_fn;
9873 /* If FN is a template function, two cases must be considered.
9874 For example:
9876 struct A {
9877 protected:
9878 template <class T> void f();
9879 };
9880 template <class T> struct B {
9881 protected:
9882 void g();
9883 };
9884 struct C : A, B<int> {
9885 using A::f; // #1
9886 using B<int>::g; // #2
9887 };
9889 In case #1 where `A::f' is a member template, DECL_ACCESS is
9890 recorded in the primary template but not in its specialization.
9891 We check access of FN using its primary template.
9893 In case #2, where `B<int>::g' has a DECL_TEMPLATE_INFO simply
9894 because it is a member of class template B, DECL_ACCESS is
9895 recorded in the specialization `B<int>::g'. We cannot use its
9896 primary template because `B<T>::g' and `B<int>::g' may have
9897 different access. */
9901 else
9906 }
9908 /* If we're checking for implicit delete, don't bother with argument
9909 conversions. */
9911 {
9915 /* Reject bad conversions now. */
9917 /* else continue to get conversion error. */
9918 }
9920 not_really_used:
9922 /* N3276 magic doesn't apply to nested calls. */
9925 /* No-Cleanup doesn't apply to nested calls either. */
9929 /* Find maximum size of vector to hold converted arguments. */
9936 in_consteval_if_p_temp_override icip;
9937 /* If the call is immediate function invocation, make sure
9938 taking address of immediate functions is allowed in its arguments. */
9942 /* The implicit parameters to a constructor are not considered by overload
9943 resolution, and must be of the proper type. */
9945 {
9946 tree object_arg;
9948 {
9951 }
9952 else
9953 {
9956 }
9959 /* We should never try to call the abstract constructor. */
9963 {
9967 }
9968 }
9969 /* Bypass access control for 'this' parameter. */
9971 {
9973 ? first_arg
9981 {
9983 {
9984 auto_diagnostic_group d;
9989 }
9990 else
9992 }
9994 /* The class where FN is defined. */
9997 /* See if the function member or the whole class type is declared
9998 final and the call can be devirtualized. */
10002 /* [class.mfct.non-static]: If a non-static member function of a class
10003 X is called for an object that is not of type X, or of a type
10004 derived from X, the behavior is undefined.
10006 So we can assume that anything passed as 'this' is non-null, and
10007 optimize accordingly. */
10008 /* Check that the base class is accessible. */
10011 {
10016 else
10018 }
10019 /* If fn was found by a using declaration, the conversion path
10020 will be to the derived class, not the base declaring fn. We
10021 must convert to the base. */
10024 {
10028 }
10030 /* If we know the dynamic type of the object, look up the final overrider
10031 in the BINFO. */
10034 {
10037 /* And unwind base_binfo to match. If we don't find the type we're
10038 looking for in BINFO_INHERITANCE_CHAIN, we're looking at diamond
10039 inheritance; for now do a normal virtual call in that case. */
10045 {
10049 }
10050 }
10059 else
10063 }
10068 {
10075 /* If the argument is NULL and used to (implicitly) instantiate a
10076 template function (and bind one of the template arguments to
10077 the type of 'long int'), we don't want to warn about passing NULL
10078 to non-pointer argument.
10079 For example, if we have this template function:
10081 template<typename T> void func(T x) {}
10083 we want to warn (when -Wconversion is enabled) in this case:
10085 void foo() {
10086 func<int>(NULL);
10087 }
10089 but not in this case:
10091 void foo() {
10092 func(NULL);
10093 }
10094 */
10101 /* Set user_conv_p on the argument conversions, so rvalue/base handling
10102 knows not to allow any more UDCs. This needs to happen after we
10103 process cand->warnings. */
10115 arg_complain);
10120 else
10122 }
10124 /* Default arguments */
10126 {
10132 complain);
10136 }
10138 /* Ellipsis */
10141 {
10144 {
10145 /* Do no conversions for certain magic varargs. */
10149 }
10151 {
10152 /* Don't truncate excess precision to the semantic type. */
10155 /* For other magic varargs only do decay_conversion. */
10157 }
10161 {
10162 /* Avoid infinite recursion trying to call A(...). */
10164 /* Try to call the actual copy constructor for a good error. */
10167 }
10168 else
10173 }
10179 /* Avoid performing argument transformation if warnings are disabled.
10180 When tf_warning is set and at least one of the warnings is active
10181 the check_function_arguments function might warn about something. */
10185 && (warn_nonnull
10186 || warn_format
10187 || warn_suggest_attribute_format
10189 {
10193 {
10194 /* For -Wformat undo the implicit passing by hidden reference
10195 done by convert_arg_to_ellipsis. */
10199 else
10201 }
10205 }
10208 {
10209 /* Check for passing ellipsis arguments to an inherited constructor. We
10210 could handle this by open-coding the inherited constructor rather than
10211 defining it, but let's not bother now. */
10215 {
10217 {
10221 }
10223 }
10225 /* A base constructor inheriting from a virtual base doesn't get the
10226 inherited arguments, just this and __vtt. */
10229 }
10231 /* Avoid actually calling copy constructors and copy assignment operators,
10232 if possible. */
10239 /* It's unsafe to elide the constructor when handling
10240 a noexcept-expression, it may evaluate to the wrong
10241 value (c++/53025). */
10243 {
10244 tree targ;
10249 /* Pull out the real argument, disregarding const-correctness. */
10251 /* Strip the reference binding for the constructor parameter. */
10255 /* But don't strip any other reference bindings; binding a temporary to a
10256 reference prevents copy elision. */
10262 {
10267 }
10268 else
10273 else
10276 /* In C++17 we shouldn't be copying a TARGET_EXPR except into a
10277 potentially-overlapping subobject. */
10280 || force_elide
10281 /* It's from binding the ref parm to a packed field. */
10284 /* See unsafe_copy_elision_p. */
10290 /* [class.copy]: the copy constructor is implicitly defined even if the
10291 implementation elided its use. But don't warn about deprecation when
10292 eliding a temporary, as then no copy is actually performed. */
10297 {
10301 }
10302 else
10309 /* If we're creating a temp and we already have one, don't create a
10310 new one. If we're not creating a temp but we get one, use
10311 INIT_EXPR to collapse the temp into our target. Otherwise, if the
10312 ctor is trivial, do a bitwise copy with a simple TARGET_EXPR for a
10313 temp or an INIT_EXPR otherwise. */
10315 {
10320 }
10323 {
10327 }
10328 }
10332 {
10333 /* Don't use cp_build_fold_indirect_ref, op= returns an lvalue even if
10334 the object argument isn't one. */
10343 {
10344 /* Avoid copying empty classes. */
10347 }
10349 {
10353 "assignment from temporary %<initializer_list%> does "
10357 }
10358 else
10359 {
10360 /* We must only copy the non-tail padding parts. */
10369 build_index_type
10378 }
10383 }
10385 {
10389 {
10392 no_cleanup_complain);
10393 else
10395 }
10396 }
10404 /* Warn if the built-in writes to an object of a non-trivial type. */
10411 {
10412 tree t;
10419 complain);
10425 }
10426 else
10427 {
10428 /* If FN is marked deprecated or unavailable, then we've already
10429 issued a diagnostic from mark_used above, so avoid redundantly
10430 issuing another one from build_addr_func. */
10432 UNAVAILABLE_DEPRECATED_SUPPRESS);
10438 /* We're actually invoking the function. (Immediate functions get an
10439 & when invoking it even though the user didn't use &.) */
10441 }
10447 {
10449 /* build_new_op will clear this when appropriate. */
10451 }
10453 {
10457 }
10460 }
10462 namespace
10463 {
10465 /* Return the DECL of the first non-static subobject of class TYPE
10466 that satisfies the predicate PRED or null if none can be found. */
10469 tree
10471 {
10476 {
10483 }
10489 {
10495 }
10498 }
10500 struct NonPublicField
10501 {
10503 {
10505 }
10506 };
10508 /* Return the DECL of the first non-public subobject of class TYPE
10509 or null if none can be found. */
10513 {
10515 }
10517 struct NonTrivialField
10518 {
10520 {
10522 }
10523 };
10525 /* Return the DECL of the first non-trivial subobject of class TYPE
10526 or null if none can be found. */
10530 {
10532 }
10536 /* Return true if all copy and move assignment operator overloads for
10537 class TYPE are trivial and at least one of them is not deleted and,
10538 when ACCESS is set, accessible. Return false otherwise. Set
10539 HASASSIGN to true when the TYPE has a (not necessarily trivial)
10540 copy or move assignment. */
10542 static bool
10544 {
10548 /* Iterate over overloads of the assignment operator, checking
10549 accessible copy assignments for triviality. */
10552 {
10553 /* Skip operators that aren't copy assignments. */
10560 /* Skip template assignment operators and deleted functions. */
10570 /* Break early when both properties have been determined. */
10573 }
10575 /* Return true if they're all trivial and one of the expressions
10576 TYPE() = TYPE() or TYPE() = (TYPE&)() is valid. */
10581 }
10583 /* Return true if all copy and move ctor overloads for class TYPE are
10584 trivial and at least one of them is not deleted and, when ACCESS is
10585 set, accessible. Return false otherwise. Set each element of HASCTOR[]
10586 to true when the TYPE has a (not necessarily trivial) default and copy
10587 (or move) ctor, respectively. */
10589 static bool
10591 {
10596 {
10597 /* Skip template constructors. */
10603 /* Skip ctors other than default, copy, and move. */
10619 /* Break early when both properties have been determined. */
10622 }
10625 }
10627 /* Issue a warning on a call to the built-in function FNDECL if it is
10628 a raw memory write whose destination is not an object of (something
10629 like) trivial or standard layout type with a non-deleted assignment
10630 and copy ctor. Detects const correctness violations, corrupting
10631 references, virtual table pointers, and bypassing non-trivial
10632 assignments. */
10634 static void
10637 {
10638 /* Except for bcopy where it's second, the destination pointer is
10639 the first argument for all functions handled here. Compute
10640 the index of the destination and source arguments. */
10652 /* Determine the type of the pointed-to object and whether it's
10653 a complete class type. */
10659 /* Check to see if the raw memory call is made by a non-static member
10660 function with THIS as the destination argument for the destination
10661 type. If so, and if the class has no non-trivial bases or members,
10662 be more permissive. */
10666 {
10675 }
10677 /* True if the class is trivial. */
10680 /* Set to true if DESTYPE has an accessible copy assignment. */
10682 /* True if all of the class' overloaded copy assignment operators
10683 are all trivial (and not deleted) and at least one of them is
10684 accessible. */
10687 /* Set to true if DESTTYPE has an accessible default and copy ctor,
10688 respectively. */
10691 /* True if all of the class' overloaded copy constructors are all
10692 trivial (and not deleted) and at least one of them is accessible. */
10695 /* Set FLD to the first private/protected member of the class. */
10698 /* The warning format string. */
10700 /* A suggested alternative to offer instead of the raw memory call.
10701 Empty string when none can be come up with. */
10706 {
10709 {
10710 /* Diagnose setting non-copy-assignable or non-trivial types,
10711 or types with a private member, to (potentially) non-zero
10712 bytes. Since the value of the bytes being written is unknown,
10713 suggest using assignment instead (if one exists). Also warn
10714 for writes into objects for which zero-initialization doesn't
10715 mean all bits clear (pointer-to-member data, where null is all
10716 bits set). Since the value being written is (most likely)
10717 non-zero, simply suggest assignment (but not copy assignment). */
10725 {
10728 "%qD writing to an object of type %#qT with "
10731 }
10737 }
10738 /* Fall through. */
10741 /* Similarly to the above, diagnose clearing non-trivial or non-
10742 standard layout objects, or objects of types with no assignmenmt.
10743 Since the value being written is known to be zero, suggest either
10744 copy assignment, copy ctor, or default ctor as an alternative,
10745 depending on what's available. */
10768 /* Determine the type of the source object. */
10772 else
10775 /* Since it's impossible to determine wheter the byte copy is
10776 being used in place of assignment to an existing object or
10777 as a substitute for initialization, assume it's the former.
10778 Determine the best alternative to use instead depending on
10779 what's not deleted. */
10800 srctype))
10801 {
10802 /* Warn when copying into a non-trivial object from an object
10803 of a different type other than void or char. */
10805 "%qD copying an object of non-trivial type "
10808 }
10813 srctype))
10814 {
10817 "%qD copying an object of type %#qT with "
10818 "%qs member %qD from an array of %#qT; use "
10821 }
10823 {
10828 /* Finally, warn on partial copies. */
10829 unsigned HOST_WIDE_INT typesize
10837 "a non-trivial type %#qT leaves %wu "
10840 "a non-trivial type %#qT leaves %wu "
10843 }
10858 {
10862 /* Finally, warn on reallocation into insufficient space. */
10864 "%qD moving an object of non-trivial type "
10867 sz);
10868 }
10873 }
10876 {
10880 else
10883 }
10887 }
10889 /* Build and return a call to FN, using NARGS arguments in ARGARRAY.
10890 If FN is the result of resolving an overloaded target built-in,
10891 ORIG_FNDECL is the original function decl, otherwise it is null.
10892 This function performs no overload resolution, conversion, or other
10893 high-level operations. */
10895 tree
10898 {
10899 tree fndecl;
10901 /* Remember roughly where this call is. */
10910 /* Check that arguments to builtin functions match the expectations. */
10912 && !processing_template_decl
10914 {
10917 /* We need to take care that values to BUILT_IN_NORMAL
10918 are reduced. */
10926 {
10931 && same_type_ignoring_top_level_qualifiers_p
10934 /* For __builtin_clear_padding (&var) we know the type
10935 is for a complete object, so there is no risk in clearing
10938 {
10940 "argument %u in call to function %qE "
10944 }
10945 }
10946 }
10951 /* 5.2.2/11: If a function call is a prvalue of object type: if the
10952 function call is either the operand of a decltype-specifier or the
10953 right operand of a comma operator that is the operand of a
10954 decltype-specifier, a temporary object is not introduced for the
10955 prvalue. The type of the prvalue may be incomplete. */
10957 {
10963 {
10966 }
10967 }
10969 }
10971 /* Returns the value to use for the in-charge parameter when making a
10972 call to a function with the indicated NAME.
10974 FIXME:Can't we find a neater way to do this mapping? */
10976 tree
10978 {
10980 {
10984 }
10985 else
10986 {
10992 }
10995 }
10997 /* We've built up a constructor call RET. Complain if it delegates to the
10998 constructor we're currently compiling. */
11000 static void
11002 {
11008 }
11010 /* Build a call to a constructor, destructor, or an assignment
11011 operator for INSTANCE, an expression with class type. NAME
11012 indicates the special member function to call; *ARGS are the
11013 arguments. ARGS may be NULL. This may change ARGS. BINFO
11014 indicates the base of INSTANCE that is to be passed as the `this'
11015 parameter to the member function called.
11017 FLAGS are the LOOKUP_* flags to use when processing the call.
11019 If NAME indicates a complete object constructor, INSTANCE may be
11020 NULL_TREE. In this case, the caller will call build_cplus_new to
11021 store the newly constructed object into a VAR_DECL. */
11023 tree
11026 {
11027 tree fns;
11028 /* The type of the subobject to be constructed or destroyed. */
11029 tree class_type;
11031 tree ret;
11039 {
11042 /* Shortcut to avoid lazy destructor declaration. */
11044 }
11047 {
11048 /* Resolve the name. */
11053 }
11059 /* Handle the special case where INSTANCE is NULL_TREE. */
11062 else
11063 {
11064 /* Convert to the base class, if necessary. */
11067 {
11069 /* For constructors and destructors, either the base is
11070 non-virtual, or it is virtual but we are doing the
11071 conversion from a constructor or destructor for the
11072 complete object. In either case, we can convert
11073 statically. */
11075 else
11076 {
11077 /* However, for assignment operators, we must convert
11078 dynamically if the base is virtual. */
11082 }
11083 }
11084 }
11088 /* In C++17, "If the initializer expression is a prvalue and the
11089 cv-unqualified version of the source type is the same class as the class
11090 of the destination, the initializer expression is used to initialize the
11091 destination object." Handle that here to avoid doing overload
11092 resolution. */
11096 {
11107 && (same_type_ignoring_top_level_qualifiers_p
11109 {
11118 /* Avoid change of behavior on Wunused-var-2.C. */
11121 }
11122 }
11126 /* When making a call to a constructor or destructor for a subobject
11127 that uses virtual base classes, pass down a pointer to a VTT for
11128 the subobject. */
11132 {
11133 tree vtt;
11134 tree sub_vtt;
11136 /* If the current function is a complete object constructor
11137 or destructor, then we fetch the VTT directly.
11138 Otherwise, we look it up using the VTT we were given. */
11146 else
11150 {
11153 }
11156 }
11161 complain);
11172 }
11174 /* Return the NAME, as a C string. The NAME indicates a function that
11175 is a member of TYPE. *FREE_P is set to true if the caller must
11176 free the memory returned.
11178 Rather than go through all of this, we should simply set the names
11179 of constructors and destructors appropriately, and dispense with
11180 ctor_identifier, dtor_identifier, etc. */
11184 {
11187 /* Assume that we will not allocate memory. */
11189 /* Constructors and destructors are special. */
11191 {
11192 pretty_name
11194 /* For a destructor, add the '~'. */
11196 {
11198 /* Remember that we need to free the memory allocated. */
11200 }
11201 }
11203 {
11206 TFF_PLAIN_IDENTIFIER),
11207 NULL);
11208 /* Remember that we need to free the memory allocated. */
11210 }
11211 else
11215 }
11217 /* If CANDIDATES contains exactly one candidate, return it, otherwise
11218 return NULL. */
11222 {
11230 }
11232 /* If CANDIDATE is invalid due to a bad argument type, return the
11233 pertinent conversion_info.
11235 Otherwise, return NULL. */
11239 {
11240 /* Must be an rr_arg_conversion or rr_bad_arg_conversion. */
11247 {
11256 }
11257 }
11259 /* Issue an error and note complaining about a bad argument type at a
11260 callsite with a single candidate FNDECL.
11262 ARG_LOC is the location of the argument (or UNKNOWN_LOCATION, in which
11263 case input_location is used).
11264 FROM_TYPE is the type of the actual argument; TO_TYPE is the type of
11265 the formal parameter. */
11267 void
11271 {
11272 auto_diagnostic_group d;
11276 {
11279 }
11285 parmnum);
11286 }
11288 /* Subroutine of build_new_method_call_1, for where there are no viable
11289 candidates for the call. */
11291 static void
11294 tree explicit_targs,
11295 tree basetype,
11299 {
11300 auto_diagnostic_group d;
11307 else
11308 {
11309 /* Special-case for when there's a single candidate that's failing
11310 due to a bad argument type. */
11314 {
11322 }
11328 {
11331 }
11339 }
11341 }
11343 /* Build a call to "INSTANCE.FN (ARGS)". If FN_P is non-NULL, it will
11344 be set, upon return, to the function called. ARGS may be NULL.
11345 This may change ARGS. */
11347 tree
11351 {
11355 tree access_binfo;
11356 tree optype;
11358 tree name;
11361 tree call;
11362 tree fn;
11365 tree orig_instance;
11366 tree orig_fns;
11373 /* We don't know what function we're going to call, yet. */
11382 {
11386 }
11391 /* Dismantle the baselink to collect all the information we need. */
11398 {
11402 }
11411 /* Under DR 147 A::A() is an invalid constructor call,
11412 not a functional cast. */
11414 {
11420 auto_diagnostic_group d;
11428 complain);
11430 }
11433 {
11438 }
11440 /* Process the argument list. */
11442 {
11447 }
11449 /* Consider the object argument to be used even if we end up selecting a
11450 static member function. */
11453 /* Figure out whether to skip the first argument for the error
11454 message we will display to users if an error occurs. We don't
11455 want to display any compiler-generated arguments. The "this"
11456 pointer hasn't been added yet. However, we must remove the VTT
11457 pointer if this is a call to a base-class constructor or
11458 destructor. */
11461 {
11462 /* Callers should explicitly indicate whether they want to ctor
11463 the complete object or just the part without virtual bases. */
11466 /* Remove the VTT pointer, if present. */
11471 /* It's OK to call destructors and constructors on cv-qualified
11472 objects. Therefore, convert the INSTANCE to the unqualified
11473 type, if necessary. */
11475 {
11479 }
11480 }
11481 else
11484 /* For the overload resolution we need to find the actual `this`
11485 that would be captured if the call turns out to be to a
11486 non-static member function. Do not actually capture it at this
11487 point. */
11489 /* Constructors don't use the enclosing 'this'. */
11491 else
11494 conversion_obstack_sentinel cos;
11496 /* The number of arguments artificial parms in ARGS; we subtract one because
11497 there's no 'this' in ARGS. */
11500 /* If CONSTRUCTOR_IS_DIRECT_INIT is set, this was a T{ } form
11501 initializer, not T({ }). */
11505 {
11512 /* If the initializer list has no elements and T is a class type with
11513 a default constructor, the object is value-initialized. Handle
11514 this here so we don't need to handle it wherever we use
11515 build_special_member_call. */
11518 /* For a user-provided default constructor, use the normal
11519 mechanisms so that protected access works. */
11524 /* If BASETYPE is an aggregate, we need to do aggregate
11525 initialization. */
11527 {
11530 }
11533 {
11537 }
11539 /* Otherwise go ahead with overload resolution. */
11544 }
11545 else
11554 {
11555 /* [dcl.init], 17.6.2.2:
11557 Otherwise, if no constructor is viable, the destination type is
11558 a (possibly cv-qualified) aggregate class A, and the initializer
11559 is a parenthesized expression-list, the object is initialized as
11560 follows...
11562 We achieve this by building up a CONSTRUCTOR, as for list-init,
11563 and setting CONSTRUCTOR_IS_PAREN_INIT to distinguish between
11564 the two. */
11570 {
11571 /* Create a CONSTRUCTOR from ARGS, e.g. {1, 2} from <1, 2>. */
11573 user_args);
11578 else
11579 {
11584 }
11585 }
11590 skip_first_for_error,
11591 user_args);
11593 }
11594 else
11595 {
11598 {
11601 tree arglist;
11604 {
11609 auto_diagnostic_group d;
11613 else
11619 }
11623 }
11624 else
11625 {
11633 {
11634 /* This is not an error, it is runtime undefined
11635 behavior. */
11644 fn);
11645 }
11650 {
11655 {
11656 /* We captured 'this' in the current lambda now that
11657 we know we really need it. */
11659 }
11661 /* We can't tell until instantiation time whether we can use
11663 else
11664 {
11667 fn);
11669 }
11670 }
11673 {
11674 /* Now we know what function is being called. */
11677 /* Build the actual CALL_EXPR. */
11680 /* Suppress warnings for if (my_struct.operator= (x)) where
11681 my_struct is implicitly converted to bool. */
11685 /* In an expression of the form `a->f()' where `f' turns
11686 out to be a static member function, `a' is
11687 none-the-less evaluated. */
11693 /* An explicit call of the form "x->~X()" has type
11694 "void". However, on platforms where destructors
11695 return "this" (i.e., those where
11696 targetm.cxx.cdtor_returns_this is true), such calls
11697 will appear to have a return value of pointer type
11698 to the low-level call machinery. We do not want to
11699 change the low-level machinery, since we want to be
11700 able to optimize "delete f()" on such platforms as
11701 "operator delete(~X(f()))" (rather than generating
11702 "t = f(), ~X(t), operator delete (t)"). */
11704 }
11705 }
11706 }
11709 {
11715 {
11718 }
11722 /* Prune all but the selected function from the original overload
11723 set so that we can avoid some duplicate work at instantiation time. */
11725 {
11728 {
11729 /* Use the selected template, not the specialization, so that
11730 this looks like an actual lookup result for sake of
11731 filter_memfn_lookup. */
11734 /* If the original overload set consists of a single function
11735 template, this isn't beneficial. */
11741 }
11745 }
11747 skip_prune:
11748 call = (build_min_non_dep_call_vec
11752 orig_args));
11757 }
11763 }
11765 /* Returns true iff standard conversion sequence ICS1 is a proper
11766 subsequence of ICS2. */
11768 static bool
11770 {
11771 /* We can assume that a conversion of the same code
11772 between the same types indicates a subsequence since we only get
11773 here if the types we are converting from are the same. */
11780 {
11787 /* At this point, ICS1 cannot be a proper subsequence of
11788 ICS2. We can get a USER_CONV when we are comparing the
11789 second standard conversion sequence of two user conversion
11790 sequences. */
11805 }
11806 }
11808 /* Returns nonzero iff DERIVED is derived from BASE. The inputs may
11809 be any _TYPE nodes. */
11811 bool
11813 {
11817 /* We only allow proper derivation here. The DERIVED_FROM_P macro
11818 considers every class derived from itself. */
11821 }
11823 /* We build the ICS for an implicit object parameter as a pointer
11824 conversion sequence. However, such a sequence should be compared
11825 as if it were a reference conversion sequence. If ICS is the
11826 implicit conversion sequence for an implicit object parameter,
11827 modify it accordingly. */
11829 static void
11831 {
11833 {
11834 /* [over.match.funcs]
11836 For non-static member functions, the type of the
11837 implicit object parameter is "reference to cv X"
11838 where X is the class of which the function is a
11839 member and cv is the cv-qualification on the member
11840 function declaration. */
11842 tree reference_type;
11844 /* The `this' parameter is a pointer to a class type. Make the
11845 implicit conversion talk about a reference to that same class
11846 type. */
11859 }
11860 }
11862 /* If *ICS is a REF_BIND set *ICS to the remainder of the conversion,
11863 and return the initial reference binding conversion. Otherwise,
11864 leave *ICS unchanged and return NULL. */
11868 {
11870 {
11875 }
11878 }
11880 /* Get the expression at the beginning of the conversion chain C. */
11882 static tree
11884 {
11889 }
11891 /* Return a tree representing the number of elements initialized by the
11892 list-initialization C. The caller must check that C converts to an
11893 array type. */
11895 static tree
11897 {
11898 /* If the array we're converting to has a dimension, we'll use that. */
11901 else
11902 {
11903 /* Otherwise, we look at how many elements the constructor we're
11904 initializing from has. */
11907 }
11908 }
11910 /* True iff C is a conversion that binds a reference or a pointer to
11911 an array of unknown bound. */
11915 {
11916 /* ck_ref_bind won't have the reference stripped. */
11918 /* ck_qual won't have the pointer stripped. */
11922 }
11924 /* Compare two implicit conversion sequences according to the rules set out in
11925 [over.ics.rank]. Return values:
11927 1: ics1 is better than ics2
11928 -1: ics2 is better than ics1
11929 0: ics1 and ics2 are indistinguishable */
11931 static int
11933 {
11934 tree from_type1;
11935 tree from_type2;
11936 tree to_type1;
11937 tree to_type2;
11944 /* REF_BINDING is nonzero if the result of the conversion sequence
11945 is a reference type. In that case REF_CONV is the reference
11946 binding conversion. */
11950 /* Compare badness before stripping the reference conversion. */
11956 /* Handle implicit object parameters. */
11960 /* Handle reference parameters. */
11964 /* List-initialization sequence L1 is a better conversion sequence than
11965 list-initialization sequence L2 if L1 converts to
11966 std::initializer_list<X> for some X and L2 does not. */
11972 /* [over.ics.rank]
11974 When comparing the basic forms of implicit conversion sequences (as
11975 defined in _over.best.ics_)
11977 --a standard conversion sequence (_over.ics.scs_) is a better
11978 conversion sequence than a user-defined conversion sequence
11979 or an ellipsis conversion sequence, and
11981 --a user-defined conversion sequence (_over.ics.user_) is a
11982 better conversion sequence than an ellipsis conversion sequence
11983 (_over.ics.ellipsis_). */
11984 /* Use BAD_CONVERSION_RANK because we already checked for a badness
11985 mismatch. If both ICS are bad, we try to make a decision based on
11986 what would have happened if they'd been good. This is not an
11987 extension, we'll still give an error when we build up the call; this
11988 just helps us give a more helpful error message. */
11998 /* Both conversions are ellipsis conversions. */
12001 /* User-defined conversion sequence U1 is a better conversion sequence
12002 than another user-defined conversion sequence U2 if they contain the
12003 same user-defined conversion operator or constructor and if the sec-
12004 ond standard conversion sequence of U1 is better than the second
12005 standard conversion sequence of U2. */
12007 /* Handle list-conversion with the same code even though it isn't always
12008 ranked as a user-defined conversion and it doesn't have a second
12009 standard conversion sequence; it will still have the desired effect.
12010 Specifically, we need to do the reference binding comparison at the
12011 end of this function. */
12015 {
12022 {
12027 }
12028 /* List-initialization sequence L1 is a better conversion sequence than
12029 list-initialization sequence L2 if
12031 -- L1 and L2 convert to arrays of the same element type, and either
12032 the number of elements n1 initialized by L1 is less than the number
12033 of elements n2 initialized by L2, or n1=n2 and L2 converts to an array
12034 of unknown bound and L1 does not. (Added in CWG 1307 and extended by
12035 P0388R4.) */
12040 {
12047 /* The n1 == n2 case. */
12054 else
12056 }
12057 else
12058 {
12059 /* For ambiguous or aggregate conversions, use the target type as
12060 a proxy for the conversion function. */
12063 }
12065 /* We can just fall through here, after setting up
12066 FROM_TYPE1 and FROM_TYPE2. */
12069 }
12070 else
12071 {
12075 /* We're dealing with two standard conversion sequences.
12077 [over.ics.rank]
12079 Standard conversion sequence S1 is a better conversion
12080 sequence than standard conversion sequence S2 if
12082 --S1 is a proper subsequence of S2 (comparing the conversion
12083 sequences in the canonical form defined by _over.ics.scs_,
12084 excluding any Lvalue Transformation; the identity
12085 conversion sequence is considered to be a subsequence of
12086 any non-identity conversion sequence */
12097 }
12099 /* One sequence can only be a subsequence of the other if they start with
12100 the same type. They can start with different types when comparing the
12101 second standard conversion sequence in two user-defined conversion
12102 sequences. */
12104 {
12109 }
12111 /* [over.ics.rank]
12113 Or, if not that,
12115 --the rank of S1 is better than the rank of S2 (by the rules
12116 defined below):
12118 Standard conversion sequences are ordered by their ranks: an Exact
12119 Match is a better conversion than a Promotion, which is a better
12120 conversion than a Conversion.
12122 Two conversion sequences with the same rank are indistinguishable
12123 unless one of the following rules applies:
12125 --A conversion that does not a convert a pointer, pointer to member,
12126 or std::nullptr_t to bool is better than one that does.
12128 The ICS_STD_RANK automatically handles the pointer-to-bool rule,
12129 so that we do not have to check it explicitly. */
12138 /* A conversion from scalar arithmetic type to complex is worse than a
12139 conversion between scalar arithmetic types. */
12146 {
12149 else
12151 }
12153 {
12154 /* A conversion in either direction between floating-point type FP1 and
12155 floating-point type FP2 is better than a conversion in the same
12156 direction between FP1 and arithmetic type T3 if
12157 - the floating-point conversion rank of FP1 is equal to the rank of
12158 FP2, and
12159 - T3 is not a floating-point type, or T3 is a floating-point type
12160 whose rank is not equal to the rank of FP1, or the floating-point
12161 conversion subrank of FP2 is greater than the subrank of T3. */
12168 {
12171 }
12174 /* Only apply this rule if at least one of the 3 types is
12175 extended floating-point type, otherwise keep them as
12176 before for compatibility reasons with types like __float128.
12177 float, double and long double alone have different conversion
12178 ranks and so when just those 3 types are involved, this
12179 rule doesn't trigger. */
12183 {
12185 {
12188 }
12190 {
12191 /* cp_compare_floating_point_conversion_ranks returns -1, 0 or 1
12192 if the conversion rank is equal (-1 or 1 if the subrank is
12193 different). */
12195 fp2),
12197 {
12198 /* Conversion ranks of FP1 and FP2 are equal. */
12203 /* FP1 <-> FP2 conversion is better. */
12208 /* Conversion subrank of FP2 is greater than subrank of T3.
12209 FP1 <-> FP2 conversion is better. */
12212 /* Conversion subrank of FP2 is less than subrank of T3.
12213 FP1 <-> T3 conversion is better. */
12215 }
12220 /* Conversion ranks of FP1 and FP2 are not equal, conversion
12221 ranks of FP1 and T3 are equal.
12222 FP1 <-> T3 conversion is better. */
12224 }
12225 }
12226 }
12232 {
12237 }
12238 /* The rules for pointers to members A::* are just like the rules
12239 for pointers A*, except opposite: if B is derived from A then
12240 A::* converts to B::*, not vice versa. For that reason, we
12241 switch the from_ and to_ variables here. */
12248 {
12253 }
12258 {
12259 /* This was one of the pointer or pointer-like conversions.
12261 [over.ics.rank]
12263 --If class B is derived directly or indirectly from class A,
12264 conversion of B* to A* is better than conversion of B* to
12265 void*, and conversion of A* to void* is better than
12266 conversion of B* to void*. */
12269 {
12271 deref_from_type2))
12274 deref_from_type1))
12276 }
12279 {
12281 {
12283 {
12285 deref_to_type1))
12287 }
12288 /* We know that DEREF_TO_TYPE1 is `void' here. */
12290 deref_to_type2))
12292 }
12293 }
12296 {
12297 /* [over.ics.rank]
12299 --If class B is derived directly or indirectly from class A
12300 and class C is derived directly or indirectly from B,
12302 --conversion of C* to B* is better than conversion of C* to
12303 A*,
12305 --conversion of B* to A* is better than conversion of C* to
12306 A* */
12308 {
12310 deref_to_type2))
12313 deref_to_type1))
12315 }
12317 {
12319 deref_from_type1))
12322 deref_from_type2))
12324 }
12325 }
12326 }
12329 {
12332 /* [over.ics.rank]
12334 --binding of an expression of type C to a reference of type
12335 B& is better than binding an expression of type C to a
12336 reference of type A&
12338 --conversion of C to B is better than conversion of C to A, */
12341 {
12346 }
12347 }
12350 {
12353 /* [over.ics.rank]
12355 --binding of an expression of type B to a reference of type
12356 A& is better than binding an expression of type C to a
12357 reference of type A&,
12359 --conversion of B to A is better than conversion of C to A */
12362 {
12367 }
12368 }
12370 /* [over.ics.rank]
12372 --S1 and S2 differ only in their qualification conversion and yield
12373 similar types T1 and T2 (_conv.qual_), respectively, and the cv-
12374 qualification signature of type T1 is a proper subset of the cv-
12375 qualification signature of type T2 */
12379 {
12383 }
12385 /* [over.ics.rank]
12387 --S1 and S2 are reference bindings (_dcl.init.ref_) and neither refers
12388 to an implicit object parameter of a non-static member function
12389 declared without a ref-qualifier, and either S1 binds an lvalue
12390 reference to an lvalue and S2 binds an rvalue reference or S1 binds an
12391 rvalue reference to an rvalue and S2 binds an lvalue reference (C++0x
12392 draft standard, 13.3.3.2)
12394 --S1 and S2 are reference bindings (_dcl.init.ref_), and the
12395 types to which the references refer are the same type except for
12396 top-level cv-qualifiers, and the type to which the reference
12397 initialized by S2 refers is more cv-qualified than the type to
12398 which the reference initialized by S1 refers.
12400 DR 1328 [over.match.best]: the context is an initialization by
12401 conversion function for direct reference binding (13.3.1.6) of a
12402 reference to function type, the return type of F1 is the same kind of
12403 reference (i.e. lvalue or rvalue) as the reference being initialized,
12404 and the return type of F2 is not. */
12407 {
12414 {
12418 /* Don't prefer a bad conversion that drops cv-quals to a bad
12419 conversion with the wrong rvalueness. */
12423 }
12426 {
12427 /* Per P0388R4:
12429 void f (int(&)[]), // (1)
12430 f (int(&)[1]), // (2)
12431 f (int*); // (3)
12433 (2) is better than (1), but (3) should be equal to (1) and to
12434 (2). For that reason we don't use ck_qual for (1) which would
12435 give it the cr_exact rank while (3) remains ck_identity.
12436 Therefore we compare (1) and (2) here. For (1) we'll have
12438 ck_ref_bind <- ck_identity
12439 int[] & int[1]
12441 so to handle this we must look at ref_conv. */
12452 {
12453 /* Prefer the one that drops fewer cv-quals. */
12458 }
12460 }
12461 }
12463 /* [over.ics.rank]
12465 Per CWG 1601:
12466 -- A conversion that promotes an enumeration whose underlying type
12467 is fixed to its underlying type is better than one that promotes to
12468 the promoted underlying type, if the two are different. */
12474 {
12478 {
12485 }
12486 }
12488 /* Neither conversion sequence is better than the other. */
12490 }
12492 /* The source type for this standard conversion sequence. */
12494 static tree
12496 {
12498 }
12500 /* Note a warning about preferring WINNER to LOSER. We do this by storing
12501 a pointer to LOSER and re-running joust to produce the warning if WINNER
12502 is actually used. */
12504 static void
12506 {
12512 }
12514 /* CAND is a constructor candidate in joust in C++17 and up. If it copies a
12515 prvalue returned from a conversion function, return true. Otherwise, return
12516 false. */
12518 static bool
12520 {
12530 {
12536 }
12538 }
12540 /* True if the defining declarations of the two candidates have equivalent
12541 parameters. */
12543 static bool
12545 {
12552 /* We don't look at c1->template_decl because that's only set for primary
12553 templates, not e.g. non-template member functions of class templates. */
12557 {
12564 }
12571 {
12572 /* Ignore 'this' when comparing the parameters of a static member
12573 function with those of a non-static one. */
12576 }
12578 }
12580 /* True iff FN is a copy or move constructor or assignment operator. */
12582 static bool
12584 {
12589 }
12591 /* Compare two candidates for overloading as described in
12592 [over.match.best]. Return values:
12594 1: cand1 is better than cand2
12595 -1: cand2 is better than cand1
12596 0: cand1 and cand2 are indistinguishable */
12598 static int
12600 tsubst_flags_t complain)
12601 {
12607 /* Candidates that involve bad conversions are always worse than those
12608 that don't. */
12614 /* If we have two pseudo-candidates for conversions to the same type,
12615 or two candidates for the same function, arbitrarily pick one. */
12621 /* Prefer a non-deleted function over an implicitly deleted move
12622 constructor or assignment operator. This differs slightly from the
12623 wording for issue 1402 (which says the move op is ignored by overload
12624 resolution), but this way produces better error messages. */
12628 {
12635 }
12637 /* a viable function F1
12638 is defined to be a better function than another viable function F2 if
12639 for all arguments i, ICSi(F1) is not a worse conversion sequence than
12640 ICSi(F2), and then */
12642 /* for some argument j, ICSj(F1) is a better conversion sequence than
12643 ICSj(F2) */
12645 /* For comparing static and non-static member functions, we ignore
12646 the implicit object parameter of the non-static function. The
12647 standard says to pretend that the static function has an object
12648 parm, but that won't work with operator overloading. */
12651 {
12661 /* We're comparing a near-match list constructor and a near-match
12662 non-list constructor. Just treat them as unordered. */
12668 {
12669 /* C++23 [over.best.ics.general] says:
12670 When the parameter is the implicit object parameter of a static
12671 member function, the implicit conversion sequence is a standard
12672 conversion sequence that is neither better nor worse than any
12673 other standard conversion sequence. */
12677 }
12678 else
12679 {
12684 }
12685 }
12688 {
12694 {
12696 && warn_sign_promo
12708 {
12715 else
12720 {
12724 }
12725 else
12727 }
12730 {
12731 /* Ambiguity between normal and reversed comparison operators
12732 with the same parameter types. P2468 decided not to go with
12733 this approach to resolving the ambiguity, so pedwarn. */
12737 {
12741 else
12744 {
12745 auto_diagnostic_group d;
12747 "C++20 says that these are ambiguous, "
12749 {
12758 {
12759 /* Suggest adding const to
12760 struct A { bool operator==(const A&); }; */
12761 tree parmtype
12766 && (same_type_ignoring_top_level_qualifiers_p
12770 "try making the operator a %<const%> "
12772 }
12773 }
12774 }
12775 else
12778 }
12782 }
12784 }
12785 }
12787 /* warn about confusing overload resolution for user-defined conversions,
12788 either between a constructor and a conversion op, or between two
12789 conversion ops. */
12791 /* In C++17, the constructor might have been elided, which means that
12792 an originally null ->second_conv could become non-null. */
12796 {
12802 else
12805 /* We don't want to complain about `X::operator T1 ()'
12806 beating `X::operator T2 () const', when T2 is a no less
12807 cv-qualified version of T1. */
12810 {
12815 {
12818 }
12821 }
12822 else
12828 {
12832 auto_diagnostic_group d;
12836 {
12839 }
12840 }
12841 else
12843 }
12848 /* DR 495 moved this tiebreaker above the template ones. */
12849 /* or, if not that,
12850 the context is an initialization by user-defined conversion (see
12851 _dcl.init_ and _over.match.user_) and the standard conversion
12852 sequence from the return type of F1 to the destination type (i.e.,
12853 the type of the entity being initialized) is a better conversion
12854 sequence than the standard conversion sequence from the return type
12855 of F2 to the destination type. */
12858 {
12862 }
12864 /* CWG2735 (PR109247): A copy/move ctor/op= for which its operand uses an
12865 explicit conversion (due to list-initialization) is worse. */
12866 {
12873 {
12881 }
12882 }
12884 /* DR2327: C++17 copy elision in [over.match.ctor] (direct-init) context.
12885 The standard currently says that only constructors are candidates, but if
12886 one copies a prvalue returned by a conversion function we prefer that.
12888 Clang does something similar, as discussed at
12889 http://lists.isocpp.org/core/2017/10/3166.php
12890 http://lists.isocpp.org/core/2019/03/5721.php */
12895 {
12901 }
12903 /* or, if not that,
12904 F1 is a non-template function and F2 is a template function
12905 specialization. */
12912 /* or, if not that,
12913 F1 and F2 are template functions and the function template for F1 is
12914 more specialized than the template for F2 according to the partial
12915 ordering rules. */
12918 {
12919 winner = more_specialized_fn
12922 /* [temp.func.order]: The presence of unused ellipsis and default
12923 arguments has no effect on the partial ordering of function
12924 templates. add_function_candidate() will not have
12925 counted the "this" argument for constructors. */
12929 }
12931 /* Concepts: F1 and F2 are non-template functions with the same
12932 parameter-type-lists, and F1 is more constrained than F2 according to the
12933 partial ordering of constraints described in 13.5.4. */
12938 {
12942 }
12944 /* F2 is a rewritten candidate (12.4.1.2) and F1 is not, or F1 and F2 are
12945 rewritten candidates, and F2 is a synthesized candidate with reversed
12946 order of parameters and F1 is not. */
12948 {
12955 }
12959 /* F1 is generated from a deduction-guide (13.3.1.8) and F2 is not */
12961 {
12963 /* We distinguish between candidates from an explicit deduction guide and
12964 candidates built from a constructor based on DECL_ARTIFICIAL. */
12971 {
12972 /* Prefer the special copy guide over a declared copy/move
12973 constructor. */
12979 /* Prefer a candidate generated from a non-template constructor. */
12984 }
12985 }
12987 /* F1 is a member of a class D, F2 is a member of a base class B of D, and
12988 for all arguments the corresponding parameters of F1 and F2 have the same
12989 type (CWG 2273/2277). */
12994 {
13008 {
13010 {
13015 }
13018 }
13019 }
13021 /* Check whether we can discard a builtin candidate, either because we
13022 have two identical ones or matching builtin and non-builtin candidates.
13024 (Pedantically in the latter case the builtin which matched the user
13025 function should not be added to the overload set, but we spot it here.
13027 [over.match.oper]
13028 ... the builtin candidates include ...
13029 - do not have the same parameter type list as any non-template
13030 non-member candidate. */
13033 {
13039 {
13041 /* Two built-in candidates; arbitrarily pick one. */
13044 /* cand1 is built-in; prefer cand2. */
13046 else
13047 /* cand2 is built-in; prefer cand1. */
13049 }
13050 }
13052 /* For candidates of a multi-versioned function, make the version with
13053 the highest priority win. This version will be checked for dispatching
13054 first. If this version can be inlined into the caller, the front-end
13055 will simply make a direct call to this function. */
13061 {
13067 /* Check if cand1->fn and cand2->fn are versions of the same function. It
13068 is possible that cand1->fn and cand2->fn are function versions but of
13069 different functions. Check types to see if they are versions of the same
13070 function. */
13073 {
13074 /* Always make the version with the higher priority, more
13075 specialized, win. */
13079 else
13081 }
13082 }
13084 /* If the two function declarations represent the same function (this can
13085 happen with declarations in multiple scopes and arg-dependent lookup),
13086 arbitrarily choose one. But first make sure the default args we're
13087 using match. */
13090 {
13097 {
13098 /* Don't crash if the fn is variadic. */
13103 }
13111 {
13114 {
13116 {
13118 {
13119 auto_diagnostic_group d;
13121 "default argument mismatch in "
13123 {
13128 }
13129 }
13130 else
13132 }
13133 else
13136 }
13139 }
13142 }
13144 tweak:
13146 /* Extension: If the worst conversion for one candidate is better than the
13147 worst conversion for the other, take the first. */
13149 {
13154 {
13159 }
13165 {
13166 /* Don't choose a deleted function over ambiguity. */
13170 {
13171 auto_diagnostic_group d;
13173 "ISO C++ says that these are ambiguous, even "
13174 "though the worst conversion for the first is "
13176 {
13179 }
13180 }
13181 else
13184 }
13185 }
13189 }
13191 /* Given a list of candidates for overloading, find the best one, if any.
13192 This algorithm has a worst case of O(2n) (winner is last), and a best
13193 case of O(n/2) (totally ambiguous); much better than a sorting
13194 algorithm. */
13198 {
13203 /* Walk through the list once, comparing each current champ to the next
13204 candidate, knocking out a candidate or two with each comparison. */
13207 {
13211 else
13212 {
13214 {
13219 }
13220 else
13221 {
13224 }
13227 }
13228 }
13230 /* Make sure the champ is better than all the candidates it hasn't yet
13231 been compared to. */
13234 challenger != champ
13237 {
13241 }
13244 }
13246 /* Returns nonzero if things of type FROM can be converted to TO. */
13248 bool
13250 {
13252 /* implicit_conversion only considers user-defined conversions
13253 if it has an expression for the call argument list. */
13257 }
13259 /* Returns nonzero if things of type FROM can be converted to TO with a
13260 standard conversion. */
13262 bool
13264 {
13266 }
13268 /* Returns nonzero if ARG (of type FROM) can be converted to TO. */
13270 bool
13272 tsubst_flags_t complain)
13273 {
13277 conversion_obstack_sentinel cos;
13278 /* We want to discard any access checks done for this test,
13279 as we might not be in the appropriate access context and
13280 we'll do the check again when we actually perform the
13281 conversion. */
13288 /* Discard the access checks now. */
13292 }
13294 /* Like can_convert_arg, but allows dubious conversions as well. */
13296 bool
13298 tsubst_flags_t complain)
13299 {
13302 conversion_obstack_sentinel cos;
13303 /* Try to perform the conversion. */
13308 }
13310 /* Return an IMPLICIT_CONV_EXPR from EXPR to TYPE with bits set from overload
13311 resolution FLAGS. */
13313 tree
13315 {
13316 /* In a template, we are only concerned about determining the
13317 type of non-dependent expressions, so we do not have to
13318 perform the actual conversion. But for initializers, we
13319 need to be able to perform it at instantiation
13320 (or instantiate_non_dependent_expr) time. */
13327 }
13329 /* Convert EXPR to TYPE. Return the converted expression.
13331 Note that we allow bad conversions here because by the time we get to
13332 this point we are committed to doing the conversion. If we end up
13333 doing a bad conversion, convert_like will complain. */
13335 tree
13338 {
13344 else
13350 conversion_obstack_sentinel cos;
13357 {
13361 }
13364 else
13365 {
13366 /* Give a conversion call the same location as expr. */
13369 }
13372 }
13374 tree
13376 {
13378 LOOKUP_IMPLICIT);
13379 }
13381 /* Convert EXPR to TYPE (as a direct-initialization) if that is
13382 permitted. If the conversion is valid, the converted expression is
13383 returned. Otherwise, NULL_TREE is returned, except in the case
13384 that TYPE is a class type; in that case, an error is issued. If
13385 C_CAST_P is true, then this direct-initialization is taking
13386 place as part of a static_cast being attempted as part of a C-style
13387 cast. */
13389 tree
13391 tree expr,
13393 tsubst_flags_t complain)
13394 {
13399 /* [dcl.init]
13401 If the destination type is a (possibly cv-qualified) class type:
13403 -- If the initialization is direct-initialization ...,
13404 constructors are considered.
13406 -- If overload resolution is successful, the selected constructor
13407 is called to initialize the object, with the initializer expression
13408 or expression-list as its argument(s).
13410 -- Otherwise, if no constructor is viable, the destination type is
13411 a (possibly cv-qualified) aggregate class A, and the initializer is
13412 a parenthesized expression-list, the object is initialized as
13413 follows... */
13415 {
13420 }
13422 conversion_obstack_sentinel cos;
13425 c_cast_p,
13430 {
13431 /* In a template, we are only concerned about determining the
13432 type of non-dependent expressions, so we do not have to
13433 perform the actual conversion. But for initializers, we
13434 need to be able to perform it at instantiation
13435 (or instantiate_non_dependent_expr) time. */
13438 }
13439 else
13445 }
13447 /* When initializing a reference that lasts longer than a full-expression,
13448 this special rule applies:
13450 [class.temporary]
13452 The temporary to which the reference is bound or the temporary
13453 that is the complete object to which the reference is bound
13454 persists for the lifetime of the reference.
13456 The temporaries created during the evaluation of the expression
13457 initializing the reference, except the temporary to which the
13458 reference is bound, are destroyed at the end of the
13459 full-expression in which they are created.
13461 In that case, we store the converted expression into a new
13462 VAR_DECL in a new scope.
13464 However, we want to be careful not to create temporaries when
13465 they are not required. For example, given:
13467 struct B {};
13468 struct D : public B {};
13469 D f();
13470 const B& b = f();
13472 there is no need to copy the return value from "f"; we can just
13473 extend its lifetime. Similarly, given:
13475 struct S {};
13476 struct T { operator S(); };
13477 T t;
13478 const S& s = t;
13480 we can extend the lifetime of the return value of the conversion
13481 operator.
13483 The next several functions are involved in this lifetime extension. */
13485 /* DECL is a VAR_DECL or FIELD_DECL whose type is a REFERENCE_TYPE. The
13486 reference is being bound to a temporary. Create and return a new
13487 VAR_DECL with the indicated TYPE; this variable will store the value to
13488 which the reference is bound. */
13490 tree
13492 {
13495 /* Register the variable. */
13498 {
13499 /* Namespace-scope or local static; give it a mangled name. */
13501 /* If an initializer is visible to multiple translation units, those
13502 translation units must agree on the addresses of the
13503 temporaries. Therefore the temporaries must be given a consistent name
13504 and vague linkage. The mangled name of a temporary is the name of the
13505 non-temporary object in whose initializer they appear, prefixed with
13506 GR and suffixed with a sequence number mangled using the usual rules
13507 for a seq-id. Temporaries are numbered with a pre-order, depth-first,
13508 left-to-right walk of the complete initializer. */
13514 }
13515 else
13516 /* Create a new cleanup level if necessary. */
13520 }
13522 /* EXPR is the initializer for a variable DECL of reference or
13523 std::initializer_list type. Create, push and return a new VAR_DECL
13524 for the initializer so that it will live as long as DECL. Any
13525 cleanup for the new variable is returned through CLEANUP, and the
13526 code to initialize the new variable is returned through INITP. */
13528 static tree
13531 {
13532 tree init;
13533 tree type;
13534 tree var;
13536 /* Create the temporary variable. */
13540 /* If the rvalue is the result of a function call it will be
13541 a TARGET_EXPR. If it is some other construct (such as a
13542 member access expression where the underlying object is
13543 itself the result of a function call), turn it into a
13544 TARGET_EXPR here. It is important that EXPR be a
13545 TARGET_EXPR below since otherwise the INIT_EXPR will
13546 attempt to make a bitwise copy of EXPR to initialize
13547 VAR. */
13550 else
13551 {
13556 }
13560 {
13564 }
13566 /* Recursively extend temps in this initializer. */
13569 cond_guard);
13571 /* Any reference temp has a non-trivial initializer. */
13574 /* If the initializer is constant, put it in DECL_INITIAL so we get
13575 static initialization and use in constant expressions. */
13577 /* As in store_init_value. */
13580 {
13582 {
13583 /* 5.19 says that a constant expression can include an
13584 lvalue-rvalue conversion applied to "a glvalue of literal type
13585 that refers to a non-volatile temporary object initialized
13586 with a constant expression". Rather than try to communicate
13587 that this VAR_DECL is a temporary, just mark it constexpr. */
13592 }
13595 }
13596 else
13597 /* Create the INIT_EXPR that will initialize the temporary
13598 variable. */
13601 {
13606 else
13607 {
13610 {
13612 {
13614 {
13619 boolean_false_node,
13620 tf_warning_or_error);
13622 }
13625 }
13627 }
13628 }
13630 /* We must be careful to destroy the temporary only
13631 after its initialization has taken place. If the
13632 initialization throws an exception, then the
13633 destructor should not be run. We cannot simply
13634 transform INIT into something like:
13636 (INIT, ({ CLEANUP_STMT; }))
13638 because emit_local_var always treats the
13639 initializer as a full-expression. Thus, the
13640 destructor would run too early; it would run at the
13641 end of initializing the reference variable, rather
13642 than at the end of the block enclosing the
13643 reference variable.
13645 The solution is to pass back a cleanup expression
13646 which the caller is responsible for attaching to
13647 the statement tree. */
13648 }
13649 else
13650 {
13653 {
13656 tls_aggregates);
13657 else
13659 static_aggregates);
13660 }
13661 else
13662 /* Check whether the dtor is callable. */
13664 }
13665 /* Avoid -Wunused-variable warning (c++/38958). */
13672 }
13674 /* Convert EXPR to the indicated reference TYPE, in a way suitable for
13675 initializing a variable of that TYPE. */
13677 tree
13680 {
13687 conversion_obstack_sentinel cos;
13691 /* If this conversion failed, we're in C++20, and we have something like
13692 A& a(b) where A is an aggregate, try again, this time as A& a{b}. */
13695 {
13701 /* If this worked, use it. */
13704 }
13706 {
13708 {
13717 else
13721 }
13723 }
13726 /* Perform the conversion. */
13729 /* We gave an error in build_user_type_conversion_1. */
13731 else
13735 }
13737 /* Return true if T is std::pair<const T&, const T&>. */
13739 static bool
13741 {
13742 /* First, check if we have std::pair. */
13753 /* Now see if the template arguments are both const T&. */
13763 }
13765 /* Return true if a class CTYPE is either std::reference_wrapper or
13766 std::ref_view, or a reference wrapper class. We consider a class
13767 a reference wrapper class if it has a reference member. We no
13768 longer check that it has a constructor taking the same reference type
13769 since that approach still generated too many false positives. */
13771 static bool
13773 {
13775 fields;
13782 }
13784 /* A wrapper for the above suitable as a callback for dfs_walk_once. */
13786 static tree
13788 {
13791 }
13793 static bool
13795 {
13799 /* Also accept a std::pair<const T&, const T&>. */
13805 {
13812 }
13814 /* Some classes, such as std::tuple, have the reference member in its
13815 (non-direct) base class. */
13821 }
13823 /* Helper for maybe_warn_dangling_reference to find a problematic CALL_EXPR
13824 that initializes the LHS (and at least one of its arguments represents
13825 a temporary, as outlined in maybe_warn_dangling_reference), or NULL_TREE
13826 if none found. For instance:
13828 const S& s = S().self(); // S::self (&TARGET_EXPR <...>)
13829 const int& r = (42, f(1)); // f(1)
13830 const int& t = b ? f(1) : f(2); // f(1)
13831 const int& u = b ? f(1) : f(g); // f(1)
13832 const int& v = b ? f(g) : f(2); // f(2)
13833 const int& w = b ? f(g) : f(g); // NULL_TREE
13834 const int& y = (f(1), 42); // NULL_TREE
13835 const int& z = f(f(1)); // f(f(1))
13837 EXPR is the initializer. If ARG_P is true, we're processing an argument
13838 to a function; the point is to distinguish between, for example,
13840 Ref::inner (&TARGET_EXPR <D.2839, F::foo (fm)>)
13842 where we shouldn't warn, and
13844 Ref::inner (&TARGET_EXPR <D.2908, F::foo (&TARGET_EXPR <...>)>)
13846 where we should warn (Ref is a reference_like_class_p so we see through
13847 it. */
13849 static tree
13851 {
13855 {
13856 /* An attempt to reduce the number of -Wdangling-reference
13857 false positives concerning reference wrappers (c++/107532).
13858 When we encounter a reference_like_class_p, we don't warn
13859 just yet; instead, we keep recursing to see if there were
13860 any temporaries behind the reference-wrapper class. */
13866 }
13869 {
13871 {
13876 OPT_Wdangling_reference)
13877 /* Don't emit a false positive for:
13878 std::vector<int> v = ...;
13879 std::vector<int>::const_iterator it = v.begin();
13880 const int &r = *it++;
13881 because R refers to one of the int elements of V, not to
13882 a temporary object. Member operator* may return a reference
13883 but probably not to one of its arguments. */
13890 /* If the function doesn't return a reference, don't warn. This
13891 can be e.g.
13892 const int& z = std::min({1, 2, 3, 4, 5, 6, 7});
13893 which doesn't dangle: std::min here returns an int.
13895 If the function returns a std::pair<const T&, const T&>, we
13896 warn, to detect e.g.
13897 std::pair<const int&, const int&> v = std::minmax(1, 2);
13898 which also creates a dangling reference, because std::minmax
13899 returns std::pair<const T&, const T&>(b, a). */
13903 /* Here we're looking to see if any of the arguments is a temporary
13904 initializing a reference parameter. */
13906 {
13908 /* Check that this argument initializes a reference, except for
13909 the argument initializing the object of a member function. */
13916 /* Recurse to see if the argument is a temporary. It could also
13917 be another call taking a temporary and returning it and
13918 initializing this reference parameter. */
13921 /* Don't warn about member function like:
13922 std::any a(...);
13923 S& s = a.emplace<S>({0}, 0);
13924 which constructs a new object and returns a reference to it, but
13925 we still want to detect:
13926 struct S { const S& self () { return *this; } };
13927 const S& s = S().self();
13928 where 's' dangles. If we've gotten here, the object this function
13929 is invoked on is not a temporary. */
13932 }
13934 }
13947 }
13948 }
13950 /* Implement -Wdangling-reference, to detect cases like
13952 int n = 1;
13953 const int& r = std::max(n - 1, n + 1); // r is dangling
13955 This creates temporaries from the arguments, returns a reference to
13956 one of the temporaries, but both temporaries are destroyed at the end
13957 of the full expression.
13959 This works by checking if a reference is initialized with a function
13960 that returns a reference, and at least one parameter of the function
13961 is a reference that is bound to a temporary. It assumes that such a
13962 function actually returns one of its arguments.
13964 DECL is the reference being initialized, INIT is the initializer. */
13966 static void
13968 {
13972 /* Only warn if what we're initializing has type T&& or const T&, or
13973 std::pair<const T&, const T&>. (A non-const lvalue reference can't
13974 bind to a temporary.) */
13980 /* Don't suppress the diagnostic just because the call comes from
13981 a system header. If the DECL is not in a system header, or if
13982 -Wsystem-headers was provided, warn. */
13983 auto wsh
13988 {
13989 auto_diagnostic_group d;
13994 }
13995 }
13997 /* If *P is an xvalue expression, prevent temporary lifetime extension if it
13998 gets used to initialize a reference. */
14000 static tree
14002 {
14008 /* Change a TARGET_EXPR from prvalue to xvalue. */
14013 }
14015 /* Subroutine of extend_ref_init_temps. Possibly extend one initializer,
14016 which is bound either to a reference or a std::initializer_list. */
14018 static tree
14021 {
14022 /* CWG1299 (C++20): The temporary object to which the reference is bound or
14023 the temporary object that is the complete object of a subobject to which
14024 the reference is bound persists for the lifetime of the reference if the
14025 glvalue to which the reference is bound was obtained through one of the
14026 following:
14027 - a temporary materialization conversion ([conv.rval]),
14028 - ( expression ), where expression is one of these expressions,
14029 - subscripting ([expr.sub]) of an array operand, where that operand is one
14030 of these expressions,
14031 - a class member access ([expr.ref]) using the . operator where the left
14032 operand is one of these expressions and the right operand designates a
14033 non-static data member of non-reference type,
14034 - a pointer-to-member operation ([expr.mptr.oper]) using the .* operator
14035 where the left operand is one of these expressions and the right operand
14036 is a pointer to data member of non-reference type,
14037 - a const_cast ([expr.const.cast]), static_cast ([expr.static.cast]),
14038 dynamic_cast ([expr.dynamic.cast]), or reinterpret_cast
14039 ([expr.reinterpret.cast]) converting, without a user-defined conversion,
14040 a glvalue operand that is one of these expressions to a glvalue that
14041 refers to the object designated by the operand, or to its complete
14042 object or a subobject thereof,
14043 - a conditional expression ([expr.cond]) that is a glvalue where the
14044 second or third operand is one of these expressions, or
14045 - a comma expression ([expr.comma]) that is a glvalue where the right
14046 operand is one of these expressions. */
14048 /* FIXME several cases are still handled wrong (101572, 81420). */
14054 {
14057 cond_guard);
14059 }
14063 {
14064 /* A pointer-to-member operation. */
14067 cond_guard);
14069 }
14071 {
14078 {
14081 tf_warning_or_error);
14084 tf_warning_or_error);
14085 }
14092 {
14095 tf_warning_or_error);
14098 tf_warning_or_error);
14099 }
14101 }
14104 /* Deal with binding to a subobject. */
14109 {
14117 }
14119 }
14121 /* INIT is part of the initializer for DECL. If there are any
14122 reference or initializer lists being initialized, extend their
14123 lifetime to match that of DECL. */
14125 tree
14128 {
14137 else
14138 {
14143 {
14144 /* [dcl.init] When initializing an aggregate from a parenthesized list
14145 of values... a temporary object bound to a reference does not have
14146 its lifetime extended. */
14151 {
14152 /* The temporary array underlying a std::initializer_list
14153 is handled like a reference temporary. */
14156 cond_guard);
14158 }
14159 else
14160 {
14166 cond_guard);
14167 }
14171 }
14172 }
14175 }
14177 /* Returns true iff an initializer for TYPE could contain temporaries that
14178 need to be extended because they are bound to references or
14179 std::initializer_list. */
14181 bool
14183 {
14188 {
14195 }
14197 }
14199 /* Returns true iff TYPE is some variant of std::initializer_list. */
14201 bool
14203 {
14208 /* Look through typedefs. */
14213 }
14215 /* Returns true iff DECL is a list constructor: i.e. a constructor which
14216 will accept an argument list of a single std::initializer_list<T>. */
14218 bool
14220 {
14222 tree arg;
14234 /* There are more non-defaulted parms. */
14238 }
14240 /* We know that can_convert_arg_bad already said "no" when trying to convert
14241 FROM to TO with ARG and FLAGS. Try to figure out if it was because
14242 an explicit conversion function was skipped when looking for a way to
14243 perform the conversion. At this point we've already printed an error. */
14245 void
14247 {
14251 conversion_obstack_sentinel cos;
14255 /* Ay, the conversion would have worked in direct-init context. */
14262 }