| blob | f978ea73f3d70cc60d6f75f6777ebe3bbb6716ee |
1 /* Functions related to invoking -*- C++ -*- methods and overloaded functions.
2 Copyright (C) 1987-2018 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. */
45 /* The various kinds of conversion. */
48 ck_identity,
49 ck_lvalue,
50 ck_fnptr,
51 ck_qual,
52 ck_std,
53 ck_ptr,
54 ck_pmem,
55 ck_base,
56 ck_ref_bind,
57 ck_user,
58 ck_ambig,
59 ck_list,
60 ck_aggr,
61 ck_rvalue
62 };
64 /* The rank of the conversion. Order of the enumerals matters; better
65 conversions should come earlier in the list. */
68 cr_identity,
69 cr_exact,
70 cr_promotion,
71 cr_std,
72 cr_pbool,
73 cr_user,
74 cr_ellipsis,
75 cr_bad
76 };
78 /* An implicit conversion sequence, in the sense of [over.best.ics].
79 The first conversion to be performed is at the end of the chain.
80 That conversion is always a cr_identity conversion. */
83 /* The kind of conversion represented by this step. */
84 conversion_kind kind;
85 /* The rank of this conversion. */
86 conversion_rank rank;
90 /* True if this conversion would be permitted with a bending of
91 language standards, e.g. disregarding pointer qualifiers or
92 converting integers to pointers. */
94 /* If KIND is ck_ref_bind ck_base_conv, true to indicate that a
95 temporary should be created to hold the result of the
96 conversion. If KIND is ck_ambig, true if the context is
97 copy-initialization. */
99 /* If KIND is ck_ptr or ck_pmem, true to indicate that a conversion
100 from a pointer-to-derived to pointer-to-base is being performed. */
102 /* If KIND is ck_ref_bind, true when either an lvalue reference is
103 being bound to an lvalue expression or an rvalue reference is
104 being bound to an rvalue expression. If KIND is ck_rvalue,
105 true when we are treating an lvalue as an rvalue (12.8p33). If
106 KIND is ck_base, always false. If ck_identity, we will be
107 binding a reference directly or decaying to a pointer. */
110 /* The type of the expression resulting from the conversion. */
111 tree type;
113 /* The next conversion in the chain. Since the conversions are
114 arranged from outermost to innermost, the NEXT conversion will
115 actually be performed before this conversion. This variant is
116 used only when KIND is neither ck_identity, ck_ambig nor
117 ck_list. Please use the next_conversion function instead
118 of using this field directly. */
120 /* The expression at the beginning of the conversion chain. This
121 variant is used only if KIND is ck_identity or ck_ambig. */
122 tree expr;
123 /* The array of conversions for an initializer_list, so this
124 variant is used only when KIN D is ck_list. */
127 /* The function candidate corresponding to this conversion
128 sequence. This field is only used if KIND is ck_user. */
130 };
132 #define CONVERSION_RANK(NODE) \
133 ((NODE)->bad_p ? cr_bad \
134 : (NODE)->ellipsis_p ? cr_ellipsis \
135 : (NODE)->user_conv_p ? cr_user \
136 : (NODE)->rank)
138 #define BAD_CONVERSION_RANK(NODE) \
139 ((NODE)->ellipsis_p ? cr_ellipsis \
140 : (NODE)->user_conv_p ? cr_user \
141 : (NODE)->rank)
150 tsubst_flags_t);
155 #define convert_like(CONV, EXPR, COMPLAIN) \
156 convert_like_real ((CONV), (EXPR), NULL_TREE, 0, \
159 #define convert_like_with_context(CONV, EXPR, FN, ARGNO, COMPLAIN ) \
160 convert_like_real ((CONV), (EXPR), (FN), (ARGNO), \
168 tsubst_flags_t);
180 static void add_builtin_candidates
183 static void add_builtin_candidate
187 static void build_builtin_candidate
197 tsubst_flags_t);
199 tsubst_flags_t);
219 tsubst_flags_t);
223 /* Returns nonzero iff the destructor name specified in NAME matches BASETYPE.
224 NAME can take many forms... */
226 bool
228 {
229 /* Just accept something we've already complained about. */
238 {
243 else
245 }
246 else
247 {
248 /* In the case of:
250 template <class T> struct S { ~S(); };
251 int i;
252 i.~S();
254 NAME will be a class template. */
257 }
262 }
264 /* We want the address of a function or method. We avoid creating a
265 pointer-to-member function. */
267 tree
269 {
272 /* We have to do these by hand to avoid real pointer to member
273 functions. */
275 {
277 {
281 complain);
282 }
284 }
285 else
289 }
291 /* Build a CALL_EXPR, we can handle FUNCTION_TYPEs, METHOD_TYPEs, or
292 POINTER_TYPE to those. Note, pointer to member function types
293 (TYPE_PTRMEMFUNC_P) must be handled by our callers. There are
294 two variants. build_call_a is the primitive taking an array of
295 arguments, while build_call_n is a wrapper that handles varargs. */
297 tree
299 {
302 else
303 {
313 }
314 }
316 /* Update various flags in cfun and the call itself based on what is being
317 called. Split out of build_call_a so that bot_manip can use it too. */
319 void
321 {
325 /* We check both the decl and the type; a function may be known not to
326 throw without being declared throw(). */
340 }
342 tree
344 {
345 tree decl;
346 tree result_type;
347 tree fntype;
357 /* An rvalue has no cv-qualifiers. */
368 {
369 /* We invoke build_call directly for several library
370 functions. These may have been declared normally if
371 we're building libgcc, so we can't just check
372 DECL_ARTIFICIAL. */
377 }
383 /* Don't pass empty class objects by value. This is useful
384 for tags in STL, which are used to control overload resolution.
385 We don't need to handle other cases of copying empty classes. */
388 {
392 {
396 }
397 }
400 }
402 /* New overloading code. */
409 };
411 /* Information for providing diagnostics about why overloading failed. */
414 rr_none,
415 rr_arity,
416 rr_explicit_conversion,
417 rr_template_conversion,
418 rr_arg_conversion,
419 rr_bad_arg_conversion,
420 rr_template_unification,
421 rr_invalid_copy,
422 rr_inherited_ctor,
423 rr_constraint_failure
424 };
427 /* The index of the argument, 0-based. */
429 /* The actual argument or its type. */
430 tree from;
431 /* The type of the parameter. */
432 tree to_type;
433 };
438 /* Information about an arity mismatch. */
440 /* The expected number of arguments. */
442 /* The actual number of arguments in the call. */
444 /* Whether the call was a varargs call. */
447 /* Information about an argument conversion mismatch. */
449 /* Same, but for bad argument conversions. */
451 /* Information about template unification failures. These are the
452 parameters passed to fn_type_unification. */
454 tree tmpl;
455 tree explicit_targs;
459 tree return_type;
460 unification_kind_t strict;
463 /* Information about template instantiation failures. These are the
464 parameters passed to instantiate_template. */
466 tree tmpl;
467 tree targs;
470 };
473 /* The FUNCTION_DECL that will be called if this candidate is
474 selected by overload resolution. */
475 tree fn;
476 /* If not NULL_TREE, the first argument to use when calling this
477 function. */
478 tree first_arg;
479 /* The rest of the arguments to use when calling this function. If
480 there are no further arguments this may be NULL or it may be an
481 empty vector. */
483 /* The implicit conversion sequences for each of the arguments to
484 FN. */
486 /* The number of implicit conversion sequences. */
488 /* If FN is a user-defined conversion, the standard conversion
489 sequence from the type returned by FN to the desired destination
490 type. */
493 /* If FN is a member function, the binfo indicating the path used to
494 qualify the name of FN at the call site. This path is used to
495 determine whether or not FN is accessible if it is selected by
496 overload resolution. The DECL_CONTEXT of FN will always be a
497 (possibly improper) base of this binfo. */
498 tree access_path;
499 /* If FN is a non-static member function, the binfo indicating the
500 subobject to which the `this' pointer should be converted if FN
501 is selected by overload resolution. The type pointed to by
502 the `this' pointer must correspond to the most derived class
503 indicated by the CONVERSION_PATH. */
504 tree conversion_path;
505 tree template_decl;
506 tree explicit_targs;
511 /* The flags active in add_candidate. */
513 };
515 /* Returns true iff T is a null pointer constant in the sense of
516 [conv.ptr]. */
518 bool
520 {
523 /* [conv.ptr]
525 A null pointer constant is an integral constant expression
526 (_expr.const_) rvalue of integer type that evaluates to zero or
527 an rvalue of type std::nullptr_t. */
532 {
535 /* Core issue 903 says only literal 0 is a null pointer constant. */
542 }
544 {
549 }
552 }
554 /* Returns true iff T is a null member pointer value (4.11). */
556 bool
558 {
567 else
569 }
571 /* Returns nonzero if PARMLIST consists of only default parms,
572 ellipsis, and/or undeduced parameter packs. */
574 bool
576 {
583 }
585 /* Allocate N bytes of memory from the conversion obstack. The memory
586 is zeroed before being returned. */
590 {
593 {
596 }
600 }
602 /* Allocate rejection reasons. */
606 {
611 }
615 {
621 }
625 {
632 }
636 {
643 }
647 {
653 }
657 {
663 }
670 {
677 /* Copy args to our own storage. */
685 }
689 {
691 }
695 {
698 }
702 {
705 }
707 // Build a constraint failure record, saving information into the
708 // template_instantiation field of the rejection. If FN is not a template
709 // declaration, the TMPL member is the FN declaration and TARGS is empty.
713 {
716 {
719 }
720 else
721 {
724 }
726 }
728 /* Dynamically allocate a conversion. */
732 {
737 }
739 /* Make sure that all memory on the conversion obstack has been
740 freed. */
742 void
744 {
748 }
750 /* Dynamically allocate an array of N conversions. */
754 {
756 }
760 {
764 /* Note that the caller is responsible for filling in t->cand for
765 user-defined conversions. */
771 {
788 }
794 }
796 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
797 specialization of std::initializer_list<T>, if such a conversion is
798 possible. */
802 {
808 tree val;
810 /* Within a list-initialization we can have more user-defined
811 conversions. */
813 /* But no narrowing conversions. */
816 /* Can't make an array of these types. */
823 {
824 conversion *sub
831 }
839 {
847 }
850 }
852 /* Return the next conversion of the conversion chain (if applicable),
853 or NULL otherwise. Please use this function instead of directly
854 accessing fields of struct conversion. */
858 {
865 }
867 /* Subroutine of build_aggr_conv: check whether CTOR, a braced-init-list,
868 is a valid aggregate initializer for array type ATYPE. */
870 static bool
872 {
876 {
882 else
884 complain);
887 }
889 }
891 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
892 aggregate class, if such a conversion is possible. */
896 {
902 /* We already called reshape_init in implicit_conversion. */
904 /* The conversions within the init-list aren't affected by the enclosing
905 context; they're always simple copy-initialization. */
909 {
911 tree val;
919 /* Value-initialization of reference is ill-formed. */
921 else
922 {
926 }
932 else
934 complain);
941 }
953 }
955 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
956 array type, if such a conversion is possible. */
960 {
965 tree val;
970 /* We might need to propagate the size from the element to the array. */
975 {
979 }
984 {
985 conversion *sub
997 }
1006 }
1008 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
1009 complex type, if such a conversion is possible. */
1013 tsubst_flags_t complain)
1014 {
1019 tree val;
1030 {
1031 conversion *sub
1043 }
1052 }
1054 /* Build a representation of the identity conversion from EXPR to
1055 itself. The TYPE should match the type of EXPR, if EXPR is non-NULL. */
1059 {
1067 }
1069 /* Converting from EXPR to TYPE was ambiguous in the sense that there
1070 were multiple user-defined conversions to accomplish the job.
1071 Build a conversion that indicates that ambiguity. */
1075 {
1083 }
1085 tree
1087 {
1091 }
1093 /* Returns the standard conversion path (see [conv]) from type FROM to type
1094 TO, if any. For proper handling of null pointer constants, you must
1095 also pass the expression EXPR to convert from. If C_CAST_P is true,
1096 this conversion is coming from a C-style cast. */
1101 {
1105 tree qualified_to;
1109 {
1112 }
1118 {
1120 {
1126 }
1128 {
1129 /* Necessary for eg, TEMPLATE_ID_EXPRs (c++/50961). */
1132 }
1133 }
1140 {
1143 /* Tell convert_like_real that we're using the address. */
1146 }
1147 /* Wrapping a ck_rvalue around a class prvalue (as a result of using
1148 obvalue_p) seems odd, since it's already a prvalue, but that's how we
1149 express the copy constructor call required by copy-initialization. */
1151 {
1153 {
1154 tree bitfield_type;
1157 {
1160 }
1161 }
1164 /* Tell convert_like_real to set LOOKUP_PREFER_RVALUE. */
1166 }
1168 /* Allow conversion between `__complex__' data types. */
1170 {
1171 /* The standard conversion sequence to convert FROM to TO is
1172 the standard conversion sequence to perform componentwise
1173 conversion. */
1176 complain);
1179 {
1182 }
1183 else
1187 }
1190 {
1194 }
1196 /* [conv.ptr]
1197 A null pointer constant can be converted to a pointer type; ... A
1198 null pointer constant of integral type can be converted to an
1199 rvalue of type std::nullptr_t. */
1207 {
1208 /* For backwards brain damage compatibility, allow interconversion of
1209 pointers and integers with a pedwarn. */
1212 }
1214 {
1215 /* For backwards brain damage compatibility, allow interconversion of
1216 enums and integers with a pedwarn. */
1219 }
1222 {
1223 tree to_pointee;
1224 tree from_pointee;
1227 {
1231 /* Since this is the target of a pointer, it can't have function
1232 qualifiers, so any TYPE_QUALS must be for attributes const or
1233 noreturn. Strip them. */
1240 }
1241 else
1242 {
1245 }
1249 to_pointee))
1250 ;
1254 {
1256 /* Don't try to apply restrict to void. */
1261 }
1263 {
1270 && (same_type_ignoring_top_level_qualifiers_p
1272 {
1275 }
1276 else
1278 }
1281 /* [conv.ptr]
1283 An rvalue of type "pointer to cv D," where D is a
1284 class type, can be converted to an rvalue of type
1285 "pointer to cv B," where B is a base class (clause
1286 _class.derived_) of D. If B is an inaccessible
1287 (clause _class.access_) or ambiguous
1288 (_class.member.lookup_) base class of D, a program
1289 that necessitates this conversion is ill-formed.
1290 Therefore, we use DERIVED_FROM_P, and do not check
1291 access or uniqueness. */
1293 {
1294 from_pointee
1300 }
1305 /* In a C-style cast, we ignore CV-qualification because we
1306 are allowed to perform a static_cast followed by a
1307 const_cast. */
1312 /* converting from string constant to char *. */
1316 /* Allow conversions among compatible ObjC pointer types (base
1317 conversions have been already handled above). */
1322 {
1325 }
1326 else
1330 }
1332 {
1346 else
1350 {
1352 tbase,
1358 }
1361 }
1363 {
1364 /* [conv.bool]
1366 A prvalue of arithmetic, unscoped enumeration, pointer, or pointer
1367 to member type can be converted to a prvalue of type bool. ...
1368 For direct-initialization (8.5 [dcl.init]), a prvalue of type
1369 std::nullptr_t can be converted to a prvalue of type bool; */
1375 {
1386 }
1389 }
1390 /* We don't check for ENUMERAL_TYPE here because there are no standard
1391 conversions to enum type. */
1392 /* As an extension, allow conversion to complex type. */
1394 {
1401 /* Give this a better rank if it's a promotion. */
1405 }
1411 {
1415 /* The derived-to-base conversion indicates the initialization
1416 of a parameter with base type from an object of a derived
1417 type. A temporary object is created to hold the result of
1418 the conversion unless we're binding directly to a reference. */
1420 }
1421 else
1428 }
1430 /* Returns nonzero if T1 is reference-related to T2. */
1432 bool
1434 {
1441 /* [dcl.init.ref]
1443 Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
1444 to "cv2 T2" if T1 is the same type as T2, or T1 is a base class
1445 of T2. */
1449 }
1451 /* Returns nonzero if T1 is reference-compatible with T2. */
1453 static bool
1455 {
1456 /* [dcl.init.ref]
1458 "cv1 T1" is reference compatible with "cv2 T2" if
1459 * T1 is reference-related to T2 or
1460 * T2 is "noexcept function" and T1 is "function", where the
1461 function types are otherwise the same,
1462 and cv1 is the same cv-qualification as, or greater cv-qualification
1463 than, cv2. */
1467 }
1469 /* A reference of the indicated TYPE is being bound directly to the
1470 expression represented by the implicit conversion sequence CONV.
1471 Return a conversion sequence for this binding. */
1475 {
1476 tree t;
1484 /* Mark the identity conv as to not decay to rvalue. */
1487 /* [over.ics.rank]
1489 When a parameter of reference type binds directly
1490 (_dcl.init.ref_) to an argument expression, the implicit
1491 conversion sequence is the identity conversion, unless the
1492 argument expression has a type that is a derived class of the
1493 parameter type, in which case the implicit conversion sequence is
1494 a derived-to-base Conversion.
1496 If the parameter binds directly to the result of applying a
1497 conversion function to the argument expression, the implicit
1498 conversion sequence is a user-defined conversion sequence
1499 (_over.ics.user_), with the second standard conversion sequence
1500 either an identity conversion or, if the conversion function
1501 returns an entity of a type that is a derived class of the
1502 parameter type, a derived-to-base conversion. */
1504 {
1505 /* Represent the derived-to-base conversion. */
1507 /* We will actually be binding to the base-class subobject in
1508 the derived class, so we mark this conversion appropriately.
1509 That way, convert_like knows not to generate a temporary. */
1511 }
1514 }
1516 /* Returns the conversion path from type FROM to reference type TO for
1517 purposes of reference binding. For lvalue binding, either pass a
1518 reference type to FROM or an lvalue expression to EXPR. If the
1519 reference will be bound to a temporary, NEED_TEMPORARY_P is set for
1520 the conversion returned. If C_CAST_P is true, this
1521 conversion is coming from a C-style cast. */
1525 tsubst_flags_t complain)
1526 {
1530 tree tfrom;
1533 cp_lvalue_kind gl_kind;
1537 {
1542 }
1545 {
1547 /* DR 1288: Otherwise, if the initializer list has a single element
1548 of type E and ... [T's] referenced type is reference-related to E,
1549 the object or reference is initialized from that element... */
1551 {
1557 {
1561 }
1562 }
1563 /* Otherwise, if T is a reference type, a prvalue temporary of the
1564 type referenced by T is copy-list-initialized or
1565 direct-list-initialized, depending on the kind of initialization
1566 for the reference, and the reference is bound to that temporary. */
1569 skip:;
1570 }
1573 {
1578 else
1580 }
1586 else
1589 /* Don't allow a class prvalue when LOOKUP_NO_TEMP_BIND. */
1594 /* Same mask as real_lvalue_p. */
1601 /* Figure out whether or not the types are reference-related and
1602 reference compatible. We have to do this after stripping
1603 references from FROM. */
1605 /* If this is a C cast, first convert to an appropriately qualified
1606 type, so that we can later do a const_cast to the desired type. */
1612 /* Directly bind reference when target expression's type is compatible with
1613 the reference and expression is an lvalue. In DR391, the wording in
1614 [8.5.3/5 dcl.init.ref] is changed to also require direct bindings for
1615 const and rvalue references to rvalues of compatible class type.
1616 We should also do direct bindings for non-class xvalues. */
1618 {
1619 /* [dcl.init.ref]
1621 If the initializer expression
1623 -- is an lvalue (but not an lvalue for a bit-field), and "cv1 T1"
1624 is reference-compatible with "cv2 T2,"
1626 the reference is bound directly to the initializer expression
1627 lvalue.
1629 [...]
1630 If the initializer expression is an rvalue, with T2 a class type,
1631 and "cv1 T1" is reference-compatible with "cv2 T2", the reference
1632 is bound to the object represented by the rvalue or to a sub-object
1633 within that object. */
1639 /* Handle rvalue reference to function properly. */
1640 conv->rvaluedness_matches_p
1642 else
1643 conv->rvaluedness_matches_p
1648 /* For the purposes of overload resolution, we ignore the fact
1649 this expression is a bitfield or packed field. (In particular,
1650 [over.ics.ref] says specifically that a function with a
1651 non-const reference parameter is viable even if the
1652 argument is a bitfield.)
1654 However, when we actually call the function we must create
1655 a temporary to which to bind the reference. If the
1656 reference is volatile, or isn't const, then we cannot make
1657 a temporary, so we just issue an error when the conversion
1658 actually occurs. */
1661 /* Don't allow binding of lvalues (other than function lvalues) to
1662 rvalue references. */
1667 /* Nor the reverse. */
1678 }
1679 /* [class.conv.fct] A conversion function is never used to convert a
1680 (possibly cv-qualified) object to the (possibly cv-qualified) same
1681 object type (or a reference to it), to a (possibly cv-qualified) base
1682 class of that type (or a reference to it).... */
1685 {
1686 /* [dcl.init.ref]
1688 If the initializer expression
1690 -- has a class type (i.e., T2 is a class type) can be
1691 implicitly converted to an lvalue of type "cv3 T3," where
1692 "cv1 T1" is reference-compatible with "cv3 T3". (this
1693 conversion is selected by enumerating the applicable
1694 conversion functions (_over.match.ref_) and choosing the
1695 best one through overload resolution. (_over.match_).
1697 the reference is bound to the lvalue result of the conversion
1698 in the second case. */
1700 complain);
1703 }
1705 /* From this point on, we conceptually need temporaries, even if we
1706 elide them. Only the cases above are "direct bindings". */
1710 /* [over.ics.rank]
1712 When a parameter of reference type is not bound directly to an
1713 argument expression, the conversion sequence is the one required
1714 to convert the argument expression to the underlying type of the
1715 reference according to _over.best.ics_. Conceptually, this
1716 conversion sequence corresponds to copy-initializing a temporary
1717 of the underlying type with the argument expression. Any
1718 difference in top-level cv-qualification is subsumed by the
1719 initialization itself and does not constitute a conversion. */
1721 /* [dcl.init.ref]
1723 Otherwise, the reference shall be an lvalue reference to a
1724 non-volatile const type, or the reference shall be an rvalue
1725 reference.
1727 We try below to treat this as a bad conversion to improve diagnostics,
1728 but if TO is an incomplete class, we need to reject this conversion
1729 now to avoid unnecessary instantiation. */
1734 /* We're generating a temporary now, but don't bind any more in the
1735 conversion (specifically, don't slice the temporary returned by a
1736 conversion operator). */
1739 /* Core issue 899: When [copy-]initializing a temporary to be bound
1740 to the first parameter of a copy constructor (12.8) called with
1741 a single argument in the context of direct-initialization,
1742 explicit conversion functions are also considered.
1744 So don't set LOOKUP_ONLYCONVERTING in that case. */
1755 {
1756 /* If initializing the temporary used a conversion function,
1757 recalculate the second conversion sequence. */
1761 {
1764 conversion *new_second
1770 }
1771 }
1774 /* This reference binding, unlike those above, requires the
1775 creation of a temporary. */
1779 /* [dcl.init.ref]
1781 Otherwise, the reference shall be an lvalue reference to a
1782 non-volatile const type, or the reference shall be an rvalue
1783 reference. */
1787 /* [dcl.init.ref]
1789 Otherwise, a temporary of type "cv1 T1" is created and
1790 initialized from the initializer expression using the rules for a
1791 non-reference copy initialization. If T1 is reference-related to
1792 T2, cv1 must be the same cv-qualification as, or greater
1793 cv-qualification than, cv2; otherwise, the program is ill-formed. */
1798 }
1800 /* Returns the implicit conversion sequence (see [over.ics]) from type
1801 FROM to type TO. The optional expression EXPR may affect the
1802 conversion. FLAGS are the usual overloading flags. If C_CAST_P is
1803 true, this conversion is coming from a C-style cast. */
1808 {
1815 /* Other flags only apply to the primary function in overload
1816 resolution, or after we've chosen one. */
1821 /* FIXME: actually we don't want warnings either, but we can't just
1822 have 'complain &= ~(tf_warning|tf_error)' because it would cause
1823 the regression of, eg, g++.old-deja/g++.benjamin/16077.C.
1824 We really ought not to issue that warning until we've committed
1825 to that conversion. */
1828 /* Call reshape_init early to remove redundant braces. */
1833 {
1838 }
1842 else
1849 {
1853 /* As an extension, allow list-initialization of _Complex. */
1855 {
1859 }
1861 /* Allow conversion from an initializer-list with one element to a
1862 scalar type. */
1864 {
1866 tree elt;
1872 else
1878 {
1881 /* Too many levels of braces, i.e. '{{1}}'. */
1884 }
1885 }
1888 }
1894 {
1904 {
1908 {
1909 /* "If C is not an initializer-list constructor and the
1910 initializer list has a single element of type cv U, where U is
1911 X or a class derived from X, the implicit conversion sequence
1912 has Exact Match rank if U is X, or Conversion rank if U is
1913 derived from X." */
1919 }
1921 }
1923 /* We used to try to bind a reference to a temporary here, but that
1924 is now handled after the recursive call to this function at the end
1925 of reference_binding. */
1927 }
1930 }
1932 /* Add a new entry to the list of candidates. Used by the add_*_candidate
1933 functions. ARGS will not be changed until a single candidate is
1934 selected. */
1943 {
1961 }
1963 /* Return the number of remaining arguments in the parameter list
1964 beginning with ARG. */
1966 int
1968 {
1973 n++;
1976 }
1978 /* Create an overload candidate for the function or method FN called
1979 with the argument list FIRST_ARG/ARGS and add it to CANDIDATES.
1980 FLAGS is passed on to implicit_conversion.
1982 This does not change ARGS.
1984 CTYPE, if non-NULL, is the type we want to pretend this function
1985 comes from for purposes of overload resolution. */
1992 tsubst_flags_t complain)
1993 {
1997 tree parmnode;
2003 /* At this point we should not see any functions which haven't been
2004 explicitly declared, except for friend functions which will have
2005 been found using argument dependent lookup. */
2008 /* The `this', `in_chrg' and VTT arguments to constructors are not
2009 considered in overload resolution. */
2011 {
2013 /* Bring back parameters omitted from an inherited ctor. */
2015 else
2019 {
2022 }
2023 }
2024 else
2030 /* 13.3.2 - Viable functions [over.match.viable]
2031 First, to be a viable function, a candidate function shall have enough
2032 parameters to agree in number with the arguments in the list.
2034 We need to check this first; otherwise, checking the ICSes might cause
2035 us to produce an ill-formed template instantiation. */
2039 {
2043 }
2047 {
2051 }
2053 /* An inherited constructor (12.6.3 [class.inhctor.init]) that has a first
2054 parameter of type "reference to cv C" (including such a constructor
2055 instantiated from a template) is excluded from the set of candidate
2056 functions when used to construct an object of type D with an argument list
2057 containing a single argument if C is reference-related to D. */
2059 && flag_new_inheriting_ctors
2061 {
2067 {
2070 }
2071 }
2073 /* Second, for a function to be viable, its constraints must be
2074 satisfied. */
2077 {
2080 }
2082 /* When looking for a function from a subobject from an implicit
2083 copy/move constructor/operator=, don't consider anything that takes (a
2084 reference to) an unrelated type. See c++/44909 and core 1092. */
2086 {
2092 else
2095 {
2098 ctype))
2100 }
2102 /* This only applies at the top level. */
2104 }
2109 /* Third, for F to be a viable function, there shall exist for each
2110 argument an implicit conversion sequence that converts that argument
2111 to the corresponding parameter of F. */
2116 {
2118 tree arg;
2127 else
2136 {
2142 /* The type of the implicit object parameter ('this') for
2143 overload resolution is not always the same as for the
2144 function itself; conversion functions are considered to
2145 be members of the class being converted, and functions
2146 introduced by a using-declaration are considered to be
2147 members of the class that uses them.
2149 Since build_over_call ignores the ICS for the `this'
2150 parameter, we can just change the parm type. */
2152 {
2153 parmtype = cp_build_qualified_type
2156 {
2157 /* If the function has a ref-qualifier, the implicit
2158 object parameter has reference type. */
2161 /* The special handling of 'this' conversions in compare_ics
2162 does not apply if there is a ref-qualifier. */
2164 }
2165 else
2166 {
2168 /* We don't use build_this here because we don't want to
2169 capture the object argument until we've chosen a
2170 non-static member function. */
2173 }
2174 }
2176 /* Core issue 899: When [copy-]initializing a temporary to be bound
2177 to the first parameter of a copy constructor (12.8) called with
2178 a single argument in the context of direct-initialization,
2179 explicit conversion functions are also considered.
2181 So set LOOKUP_COPY_PARM to let reference_binding know that
2182 it's being called in that context. We generalize the above
2183 to handle move constructors and template constructors as well;
2184 the standardese should soon be updated similarly. */
2188 && (same_type_ignoring_top_level_qualifiers_p
2190 {
2193 /* We allow user-defined conversions within init-lists, but
2194 don't list-initialize the copy parm, as that would mean
2195 using two levels of braces for the same type. */
2199 }
2200 else
2206 }
2207 else
2208 {
2212 }
2219 {
2223 }
2226 {
2229 }
2230 }
2232 out:
2235 }
2237 /* Create an overload candidate for the conversion function FN which will
2238 be invoked for expression OBJ, producing a pointer-to-function which
2239 will in turn be called with the argument list FIRST_ARG/ARGLIST,
2240 and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
2241 passed on to implicit_conversion.
2243 Actually, we don't really care about FN; we care about the type it
2244 converts to. There may be multiple conversion functions that will
2245 convert to that type, and we rely on build_user_type_conversion_1 to
2246 choose the best one; so when we create our candidate, we record the type
2247 instead of the function. */
2253 tsubst_flags_t complain)
2254 {
2272 /* Don't bother looking up the same type twice. */
2277 {
2283 else
2288 {
2291 /* Leave the 'cand' field null; we'll figure out the conversion in
2292 convert_like_real if this candidate is chosen. */
2294 }
2298 {
2302 }
2303 else
2304 {
2308 }
2315 {
2318 }
2325 }
2329 {
2333 }
2337 }
2339 static void
2343 {
2357 /* TRUTH_*_EXPR do "contextual conversion to bool", which means explicit
2358 conversion ops are allowed. We handle that here by just checking for
2359 boolean_type_node because other operators don't ask for it. COND_EXPR
2360 also does contextual conversion to bool for the first operand, but we
2361 handle that in build_conditional_expr, and type1 here is operand 2. */
2366 {
2373 {
2375 /* We need something for printing the candidate. */
2379 }
2381 {
2385 }
2387 }
2389 /* For COND_EXPR we rearranged the arguments; undo that now. */
2391 {
2396 complain);
2399 else
2400 {
2403 boolean_type_node);
2404 }
2405 }
2412 }
2414 static bool
2416 {
2418 }
2420 /* Returns nonzero if TYPE is a promoted arithmetic type. */
2422 static bool
2424 {
2425 /* [over.built]
2427 In this section, the term promoted integral type is used to refer
2428 to those integral types which are preserved by integral promotion
2429 (including e.g. int and long but excluding e.g. char).
2430 Similarly, the term promoted arithmetic type refers to promoted
2431 integral types plus floating types. */
2435 }
2437 /* Create any builtin operator overload candidates for the operator in
2438 question given the converted operand types TYPE1 and TYPE2. The other
2439 args are passed through from add_builtin_candidates to
2440 build_builtin_candidate.
2442 TYPE1 and TYPE2 may not be permissible, and we must filter them.
2443 If CODE is requires candidates operands of the same type of the kind
2444 of which TYPE1 and TYPE2 are, we add both candidates
2445 CODE (TYPE1, TYPE1) and CODE (TYPE2, TYPE2). */
2447 static void
2451 tsubst_flags_t complain)
2452 {
2454 {
2462 }
2465 {
2467 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2468 and VQ is either volatile or empty, there exist candidate operator
2469 functions of the form
2470 VQ T& operator++(VQ T&);
2471 T operator++(VQ T&, int);
2472 5 For every pair T, VQ), where T is an enumeration type or an arithmetic
2473 type other than bool, and VQ is either volatile or empty, there exist
2474 candidate operator functions of the form
2475 VQ T& operator--(VQ T&);
2476 T operator--(VQ T&, int);
2477 6 For every pair T, VQ), where T is a cv-qualified or cv-unqualified
2478 complete object type, and VQ is either volatile or empty, there exist
2479 candidate operator functions of the form
2480 T*VQ& operator++(T*VQ&);
2481 T*VQ& operator--(T*VQ&);
2482 T* operator++(T*VQ&, int);
2483 T* operator--(T*VQ&, int); */
2489 /* FALLTHRU */
2493 {
2496 }
2499 /* 7 For every cv-qualified or cv-unqualified object type T, there
2500 exist candidate operator functions of the form
2502 T& operator*(T*);
2504 8 For every function type T, there exist candidate operator functions of
2505 the form
2506 T& operator*(T*); */
2515 /* 9 For every type T, there exist candidate operator functions of the form
2516 T* operator+(T*);
2518 10For every promoted arithmetic type T, there exist candidate operator
2519 functions of the form
2520 T operator+(T);
2521 T operator-(T); */
2526 /* FALLTHRU */
2532 /* 11For every promoted integral type T, there exist candidate operator
2533 functions of the form
2534 T operator~(T); */
2541 /* 12For every quintuple C1, C2, T, CV1, CV2), where C2 is a class type, C1
2542 is the same type as C2 or is a derived class of C2, T is a complete
2543 object type or a function type, and CV1 and CV2 are cv-qualifier-seqs,
2544 there exist candidate operator functions of the form
2545 CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
2546 where CV12 is the union of CV1 and CV2. */
2550 {
2558 }
2561 /* 13For every pair of promoted arithmetic types L and R, there exist can-
2562 didate operator functions of the form
2563 LR operator*(L, R);
2564 LR operator/(L, R);
2565 LR operator+(L, R);
2566 LR operator-(L, R);
2567 bool operator<(L, R);
2568 bool operator>(L, R);
2569 bool operator<=(L, R);
2570 bool operator>=(L, R);
2571 bool operator==(L, R);
2572 bool operator!=(L, R);
2573 where LR is the result of the usual arithmetic conversions between
2574 types L and R.
2576 14For every pair of types T and I, where T is a cv-qualified or cv-
2577 unqualified complete object type and I is a promoted integral type,
2578 there exist candidate operator functions of the form
2579 T* operator+(T*, I);
2580 T& operator[](T*, I);
2581 T* operator-(T*, I);
2582 T* operator+(I, T*);
2583 T& operator[](I, T*);
2585 15For every T, where T is a pointer to complete object type, there exist
2586 candidate operator functions of the form112)
2587 ptrdiff_t operator-(T, T);
2589 16For every pointer or enumeration type T, there exist candidate operator
2590 functions of the form
2591 bool operator<(T, T);
2592 bool operator>(T, T);
2593 bool operator<=(T, T);
2594 bool operator>=(T, T);
2595 bool operator==(T, T);
2596 bool operator!=(T, T);
2598 17For every pointer to member type T, there exist candidate operator
2599 functions of the form
2600 bool operator==(T, T);
2601 bool operator!=(T, T); */
2608 {
2611 }
2612 /* FALLTHRU */
2625 {
2628 }
2630 {
2633 }
2634 /* Fall through. */
2650 {
2653 }
2656 {
2659 }
2665 /* FALLTHRU */
2668 {
2671 }
2673 {
2676 }
2679 /* 18For every pair of promoted integral types L and R, there exist candi-
2680 date operator functions of the form
2681 LR operator%(L, R);
2682 LR operator&(L, R);
2683 LR operator^(L, R);
2684 LR operator|(L, R);
2685 L operator<<(L, R);
2686 L operator>>(L, R);
2687 where LR is the result of the usual arithmetic conversions between
2688 types L and R. */
2696 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2700 /* 19For every triple L, VQ, R), where L is an arithmetic or enumeration
2701 type, VQ is either volatile or empty, and R is a promoted arithmetic
2702 type, there exist candidate operator functions of the form
2703 VQ L& operator=(VQ L&, R);
2704 VQ L& operator*=(VQ L&, R);
2705 VQ L& operator/=(VQ L&, R);
2706 VQ L& operator+=(VQ L&, R);
2707 VQ L& operator-=(VQ L&, R);
2709 20For every pair T, VQ), where T is any type and VQ is either volatile
2710 or empty, there exist candidate operator functions of the form
2711 T*VQ& operator=(T*VQ&, T*);
2713 21For every pair T, VQ), where T is a pointer to member type and VQ is
2714 either volatile or empty, there exist candidate operator functions of
2715 the form
2716 VQ T& operator=(VQ T&, T);
2718 22For every triple T, VQ, I), where T is a cv-qualified or cv-
2719 unqualified complete object type, VQ is either volatile or empty, and
2720 I is a promoted integral type, there exist candidate operator func-
2721 tions of the form
2722 T*VQ& operator+=(T*VQ&, I);
2723 T*VQ& operator-=(T*VQ&, I);
2725 23For every triple L, VQ, R), where L is an integral or enumeration
2726 type, VQ is either volatile or empty, and R is a promoted integral
2727 type, there exist candidate operator functions of the form
2729 VQ L& operator%=(VQ L&, R);
2730 VQ L& operator<<=(VQ L&, R);
2731 VQ L& operator>>=(VQ L&, R);
2732 VQ L& operator&=(VQ L&, R);
2733 VQ L& operator^=(VQ L&, R);
2734 VQ L& operator|=(VQ L&, R); */
2738 {
2742 {
2745 }
2746 /* FALLTHRU */
2759 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2772 {
2775 }
2780 }
2785 /* [over.built]
2787 For every pair of promoted arithmetic types L and R, there
2788 exist candidate operator functions of the form
2790 LR operator?(bool, L, R);
2792 where LR is the result of the usual arithmetic conversions
2793 between types L and R.
2795 For every type T, where T is a pointer or pointer-to-member
2796 type, there exist candidate operator functions of the form T
2797 operator?(bool, T, T); */
2801 /* That's OK. */
2804 /* Otherwise, the types should be pointers. */
2808 /* We don't check that the two types are the same; the logic
2809 below will actually create two candidates; one in which both
2810 parameter types are TYPE1, and one in which both parameter
2811 types are TYPE2. */
2822 }
2824 /* Make sure we don't create builtin candidates with dependent types. */
2828 {
2829 /* Try to recover if one of the types is non-dependent. But if
2830 there's only one type, there's nothing we can do. */
2833 /* And we lose if both are dependent. */
2836 /* Or if they have different forms. */
2844 }
2846 /* If we're dealing with two pointer types or two enumeral types,
2847 we need candidates for both of them. */
2856 {
2858 {
2860 error_mark_node,
2861 error_mark_node,
2862 CPO_CONVERSION,
2863 tf_none);
2865 {
2866 build_builtin_candidate
2870 }
2871 }
2873 build_builtin_candidate
2875 build_builtin_candidate
2878 }
2880 build_builtin_candidate
2882 }
2884 tree
2886 {
2892 }
2894 /* There are three conditions of builtin candidates:
2896 1) bool-taking candidates. These are the same regardless of the input.
2897 2) pointer-pair taking candidates. These are generated for each type
2898 one of the input types converts to.
2899 3) arithmetic candidates. According to the standard, we should generate
2900 all of these, but I'm trying not to...
2902 Here we generate a superset of the possible candidates for this particular
2903 case. That is a subset of the full set the standard defines, plus some
2904 other cases which the standard disallows. add_builtin_candidate will
2905 filter out the invalid set. */
2907 static void
2911 {
2915 /* TYPES[i] is the set of possible builtin-operator parameter types
2916 we will consider for the Ith argument. */
2921 {
2924 else
2926 }
2929 {
2930 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2931 and VQ is either volatile or empty, there exist candidate operator
2932 functions of the form
2933 VQ T& operator++(VQ T&); */
2943 /* 24There also exist candidate operator functions of the form
2944 bool operator!(bool);
2945 bool operator&&(bool, bool);
2946 bool operator||(bool, bool); */
2949 build_builtin_candidate
2956 build_builtin_candidate
2974 /* Fall through. */
2978 }
2984 {
2986 ;
2988 {
2989 tree convs;
2997 {
3002 }
3008 {
3021 {
3027 }
3031 }
3032 }
3033 else
3034 {
3039 {
3045 }
3047 }
3048 }
3050 /* Run through the possible parameter types of both arguments,
3051 creating candidates with those parameter types. */
3053 {
3055 tree u;
3059 add_builtin_candidate
3062 else
3063 add_builtin_candidate
3066 }
3070 }
3073 /* If TMPL can be successfully instantiated as indicated by
3074 EXPLICIT_TARGS and ARGLIST, adds the instantiation to CANDIDATES.
3076 TMPL is the template. EXPLICIT_TARGS are any explicit template
3077 arguments. ARGLIST is the arguments provided at the call-site.
3078 This does not change ARGLIST. The RETURN_TYPE is the desired type
3079 for conversion operators. If OBJ is NULL_TREE, FLAGS and CTYPE are
3080 as for add_function_candidate. If an OBJ is supplied, FLAGS and
3081 CTYPE are ignored, and OBJ is as for add_conv_candidate. */
3089 tsubst_flags_t complain)
3090 {
3100 tree arg;
3102 tree fn;
3106 /* We don't do deduction on the in-charge parameter, the VTT
3107 parameter or 'this'. */
3109 {
3113 /* We're deducing for a call to the result of a template conversion
3115 else
3117 }
3122 {
3125 else
3127 }
3135 {
3136 /* 12.8/6 says, "A declaration of a constructor for a class X is
3137 ill-formed if its first parameter is of type (optionally cv-qualified)
3138 X and either there are no other parameters or else all other
3139 parameters have default arguments. A member function template is never
3140 instantiated to produce such a constructor signature."
3142 So if we're trying to copy an object of the containing class, don't
3143 consider a template constructor that has a first parameter type that
3144 is just a template parameter, as we would deduce a signature that we
3145 would then reject in the code below. */
3147 {
3152 {
3156 }
3157 }
3158 }
3165 {
3168 }
3172 {
3175 }
3180 args_without_in_chrg,
3181 nargs_without_in_chrg,
3186 {
3187 /* Don't repeat unification later if it already resulted in errors. */
3191 nargs_without_in_chrg,
3193 else
3196 }
3199 {
3202 ctype))
3203 {
3204 /* We're trying to produce a constructor with a prohibited signature,
3205 as discussed above; handle here any cases we didn't catch then,
3206 such as X(X<T>). */
3209 }
3210 }
3213 /* Aha, this is a conversion function. */
3216 else
3221 /* This situation can occur if a member template of a template
3222 class is specialized. Then, instantiate_template might return
3223 an instantiation of the specialization, in which case the
3224 DECL_TI_TEMPLATE field will point at the original
3225 specialization. For example:
3227 template <class T> struct S { template <class U> void f(U);
3228 template <> void f(int) {}; };
3229 S<double> sd;
3230 sd.f(3);
3232 Here, TMPL will be template <class U> S<double>::f(U).
3233 And, instantiate template will give us the specialization
3234 template <> S<double>::f(int). But, the DECL_TI_TEMPLATE field
3235 for this will point at template <class T> template <> S<T>::f(int),
3236 so that we can find the definition. For the purposes of
3237 overload resolution, however, we want the original TMPL. */
3239 else
3244 fail:
3247 }
3256 {
3257 return
3262 }
3264 /* Create an overload candidate for the conversion function template TMPL,
3265 returning RETURN_TYPE, which will be invoked for expression OBJ to produce a
3266 pointer-to-function which will in turn be called with the argument list
3267 ARGLIST, and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
3268 passed on to implicit_conversion. */
3272 tree obj,
3276 {
3277 /* Making this work broke PR 71117 and 85118, so until the committee resolves
3278 core issue 2189, let's disable this candidate if there are any call
3279 operators. */
3283 return
3287 complain);
3288 }
3290 /* The CANDS are the set of candidates that were considered for
3291 overload resolution. Return the set of viable candidates, or CANDS
3292 if none are viable. If any of the candidates were viable, set
3293 *ANY_VIABLE_P to true. STRICT_P is true if a candidate should be
3294 considered viable only if it is strictly viable. */
3300 {
3306 /* Be strict inside templates, since build_over_call won't actually
3307 do the conversions to get pedwarns. */
3317 {
3321 {
3322 /* Be strict in the presence of a viable candidate. Also if
3323 there are template candidates, so that we get deduction errors
3324 for them instead of silently preferring a bad conversion. */
3327 {
3328 /* Put any spliced near matches back onto the main list so
3329 that we see them if there is no strict match. */
3335 }
3336 }
3339 {
3347 }
3348 else
3350 }
3353 }
3355 static bool
3357 {
3362 }
3364 /* OBJ is being used in an expression like "OBJ.f (...)". In other
3365 words, it is about to become the "this" pointer for a member
3366 function call. Take the address of the object. */
3368 static tree
3370 {
3371 /* In a template, we are only concerned about the type of the
3372 expression, so we can take a shortcut. */
3377 }
3379 /* Returns true iff functions are equivalent. Equivalent functions are
3380 not '==' only if one is a function-local extern function or if
3381 both are extern "C". */
3385 {
3394 }
3396 /* Print information about a candidate being rejected due to INFO. */
3398 static void
3400 {
3405 {
3406 /* Conversion of implicit `this' argument failed. */
3408 /* A bad conversion for 'this' must be discarding cv-quals. */
3411 from);
3412 else
3416 }
3418 {
3423 tf_warning_or_error);
3424 }
3426 /* Conversion of conversion function return value failed. */
3429 else
3432 }
3434 /* Print information about a candidate with WANT parameters and we found
3435 HAVE. */
3437 static void
3439 {
3444 }
3446 /* Print information about one overload candidate CANDIDATE. MSGSTR
3447 is the text to print before the candidate itself.
3449 NOTE: Unlike most diagnostic functions in GCC, MSGSTR is expected
3450 to have been run through gettext by the caller. This wart makes
3451 life simpler in print_z_candidates and for the translators. */
3453 static void
3456 {
3466 {
3477 else
3480 }
3487 else
3490 {
3493 }
3494 /* Give the user some information about why this candidate failed. */
3496 {
3500 {
3513 "cannot be converted to %qT with a qualification "
3519 "conversion function specialization to %qT is not an "
3524 /* We use template_unification_error_rejection if unification caused
3525 actual non-SFINAE errors, in which case we don't need to repeat
3526 them here. */
3528 {
3532 }
3533 /* Re-run template unification with diagnostics. */
3537 (make_tree_vec
3548 " a constructor taking a single argument of its own "
3552 {
3556 }
3560 "initialization from an expression of the same or derived "
3565 /* This candidate didn't have any issues or we failed to
3566 handle a particular code. Either way... */
3568 }
3569 }
3570 }
3572 static void
3574 {
3581 /* Remove non-viable deleted candidates. */
3584 {
3589 else
3591 }
3592 /* ...if there are any non-deleted ones. */
3596 /* There may be duplicates in the set of candidates. We put off
3597 checking this condition as long as possible, since we have no way
3598 to eliminate duplicates from a set of functions in less than n^2
3599 time. Now we are about to emit an error message, so it is more
3600 permissible to go slowly. */
3602 {
3604 /* Skip builtin candidates and conversion functions. */
3609 {
3613 else
3615 }
3616 }
3620 }
3622 /* USER_SEQ is a user-defined conversion sequence, beginning with a
3623 USER_CONV. STD_SEQ is the standard conversion sequence applied to
3624 the result of the conversion function to convert it to the final
3625 desired type. Merge the two sequences into a single sequence,
3626 and return the merged sequence. */
3630 {
3636 /* Find the end of the second conversion sequence. */
3638 {
3639 /* The entire sequence is a user-conversion sequence. */
3643 }
3646 /* We're binding a reference directly to the result of the conversion.
3647 build_user_type_conversion_1 stripped the REFERENCE_TYPE from the return
3648 type, but we want it back. */
3651 /* Replace the identity conversion with the user conversion
3652 sequence. */
3656 }
3658 /* Handle overload resolution for initializing an object of class type from
3659 an initializer list. First we look for a suitable constructor that
3660 takes a std::initializer_list; if we don't find one, we then look for a
3661 non-list constructor.
3663 Parameters are as for add_candidates, except that the arguments are in
3664 the form of a CONSTRUCTOR (the initializer list) rather than a vector, and
3665 the RETURN_TYPE parameter is replaced by TOTYPE, the desired type. */
3667 static void
3674 tsubst_flags_t complain)
3675 {
3678 /* We're looking for a ctor for list-initialization. */
3680 /* And we don't allow narrowing conversions. We also use this flag to
3681 avoid the copy constructor call for copy-list-initialization. */
3687 /* Always use the default constructor if the list is empty (DR 990). */
3690 ;
3691 /* If the class has a list ctor, try passing the list as a single
3692 argument first, but only consider list ctors. */
3694 {
3701 }
3703 /* Expand the CONSTRUCTOR into a new argument vec. */
3711 /* We aren't looking for list-ctors anymore. */
3713 /* We allow more user-defined conversions within an init-list. */
3719 }
3721 /* Returns the best overload candidate to perform the requested
3722 conversion. This function is used for three the overloading situations
3723 described in [over.match.copy], [over.match.conv], and [over.match.ref].
3724 If TOTYPE is a REFERENCE_TYPE, we're trying to find a direct binding as
3725 per [dcl.init.ref], so we ignore temporary bindings. */
3729 tsubst_flags_t complain)
3730 {
3732 tree fromtype;
3746 /* We represent conversion within a hierarchy using RVALUE_CONV and
3747 BASE_CONV, as specified by [over.best.ics]; these become plain
3748 constructor calls, as specified in [dcl.init]. */
3753 /* Use lookup_fnfields_slot instead of lookup_fnfields to avoid
3754 creating a garbage BASELINK; constructors can't be inherited. */
3758 {
3763 {
3764 /* [class.conv.fct] A conversion function is never used to
3765 convert a (possibly cv-qualified) object to the (possibly
3766 cv-qualified) same object type (or a reference to it), to a
3767 (possibly cv-qualified) base class of that type (or a
3768 reference to it)... */
3769 }
3770 else
3772 }
3779 /* It's OK to bind a temporary for converting constructor arguments, but
3780 not in converting the return value of a conversion operator. */
3786 {
3791 /* We should never try to call the abstract or base constructor
3792 from here. */
3798 {
3799 /* List-initialization. */
3803 }
3804 else
3805 {
3809 }
3812 {
3815 /* If totype isn't a reference, and LOOKUP_NO_TEMP_BIND isn't
3816 set, then this is copy-initialization. In that case, "The
3817 result of the call is then used to direct-initialize the
3818 object that is the destination of the copy-initialization."
3819 [dcl.init]
3821 We represent this in the conversion sequence with an
3822 rvalue conversion, which means a constructor call. */
3825 cand->second_conv
3827 }
3828 }
3831 {
3834 else
3836 }
3839 {
3843 /* If we are called to convert to a reference type, we are trying to
3844 find a direct binding, so don't even consider temporaries. If
3845 we don't find a direct binding, the caller will try again to
3846 look for a temporary binding. */
3857 {
3859 conversion *ics
3861 rettype,
3864 complain);
3866 /* If LOOKUP_NO_TEMP_BIND isn't set, then this is
3867 copy-initialization. In that case, "The result of the
3868 call is then used to direct-initialize the object that is
3869 the destination of the copy-initialization." [dcl.init]
3871 We represent this in the conversion sequence with an
3872 rvalue conversion, which means a constructor call. But
3873 don't add a second rvalue conversion if there's already
3874 one there. Which there really shouldn't be, but it's
3875 harmless since we'd add it here anyway. */
3883 {
3887 }
3890 {
3891 /* 13.3.1.5: For direct-initialization, those explicit
3892 conversion functions that are not hidden within S and
3893 yield type T or a type that can be converted to type T
3894 with a qualification conversion (4.4) are also candidate
3895 functions. */
3896 /* 13.3.1.6 doesn't have a parallel restriction, but it should;
3897 I've raised this issue with the committee. --jason 9/2011 */
3900 }
3902 {
3904 cand->reason
3907 }
3910 {
3911 /* 13.3.3.1.2: If the user-defined conversion is specified by
3912 a specialization of a conversion function template, the
3913 second standard conversion sequence shall have exact match
3914 rank. */
3917 }
3918 }
3919 }
3923 {
3927 }
3931 {
3933 {
3937 }
3946 /* If there are viable candidates, don't set ICS_BAD_FLAG; an
3947 ambiguous conversion is no worse than another user-defined
3948 conversion. */
3951 }
3953 tree convtype;
3957 /* DR 5: [in the first step of copy-initialization]...if the function
3958 is a constructor, the call initializes a temporary of the
3959 cv-unqualified version of the destination type. */
3961 else
3963 /* Build the user conversion sequence. */
3964 conv = build_conv
3966 convtype,
3972 /* Remember that this was a list-initialization. */
3976 /* Combine it with the second conversion sequence. */
3981 }
3983 /* Wrapper for above. */
3985 tree
3987 tsubst_flags_t complain)
3988 {
3990 tree ret;
3996 {
3999 else
4000 {
4003 }
4004 }
4005 else
4010 }
4012 /* Subroutine of convert_nontype_argument.
4014 EXPR is an expression used in a context that requires a converted
4015 constant-expression, such as a template non-type parameter. Do any
4016 necessary conversions (that are permitted for converted
4017 constant-expressions) to convert it to the desired type.
4019 If conversion is successful, returns the converted expression;
4020 otherwise, returns error_mark_node. */
4022 tree
4024 {
4027 tree t;
4033 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4040 /* A converted constant expression of type T is an expression, implicitly
4041 converted to type T, where the converted expression is a constant
4042 expression and the implicit conversion sequence contains only
4044 * user-defined conversions,
4045 * lvalue-to-rvalue conversions (7.1),
4046 * array-to-pointer conversions (7.2),
4047 * function-to-pointer conversions (7.3),
4048 * qualification conversions (7.5),
4049 * integral promotions (7.6),
4050 * integral conversions (7.8) other than narrowing conversions (11.6.4),
4051 * null pointer conversions (7.11) from std::nullptr_t,
4052 * null member pointer conversions (7.12) from std::nullptr_t, and
4053 * function pointer conversions (7.13),
4055 and where the reference binding (if any) binds directly. */
4060 {
4062 {
4063 /* A conversion function is OK. If it isn't constexpr, we'll
4064 complain later that the argument isn't constant. */
4066 /* The lvalue-to-rvalue conversion is OK. */
4068 /* Array-to-pointer and function-to-pointer. */
4070 /* Function pointer conversions. */
4072 /* Qualification conversions. */
4078 {
4084 }
4094 /* Integral promotion or conversion. */
4097 /* Conversion from nullptr to pointer or pointer-to-member. */
4103 /* fall through. */
4108 }
4109 }
4111 /* Avoid confusing convert_nontype_argument by introducing
4112 a redundant conversion to the same reference type. */
4115 {
4119 }
4123 else
4126 /* Free all the conversions we allocated. */
4130 }
4132 /* Do any initial processing on the arguments to a function call. */
4136 {
4138 tree arg;
4141 {
4145 {
4149 }
4152 }
4154 }
4156 /* Perform overload resolution on FN, which is called with the ARGS.
4158 Return the candidate function selected by overload resolution, or
4159 NULL if the event that overload resolution failed. In the case
4160 that overload resolution fails, *CANDIDATES will be the set of
4161 candidates considered, and ANY_VIABLE_P will be set to true or
4162 false to indicate whether or not any of the candidates were
4163 viable.
4165 The ARGS should already have gone through RESOLVE_ARGS before this
4166 function is called. */
4173 {
4175 tree explicit_targs;
4186 /* Check FN. */
4193 {
4197 }
4199 /* Add the various candidate functions. */
4204 LOOKUP_NORMAL,
4210 else
4215 }
4217 /* Print an error message about being unable to build a call to FN with
4218 ARGS. ANY_VIABLE_P indicates whether any candidate functions could
4219 be located; CANDIDATES is a possibly empty list of such
4220 functions. */
4222 static void
4225 {
4228 {
4231 }
4240 else
4245 }
4247 /* Return an expression for a call to FN (a namespace-scope function,
4248 or a static member function) with the ARGS. This may change
4249 ARGS. */
4251 tree
4253 tsubst_flags_t complain)
4254 {
4258 tree result;
4261 {
4265 }
4270 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4274 complain);
4277 {
4279 {
4280 // If there is a single (non-viable) function candidate,
4281 // let the error be diagnosed by cp_build_function_call_vec.
4286 // Otherwise, emit notes for non-viable candidates.
4288 }
4290 }
4291 else
4292 {
4294 /* If fn is template_id_expr, the call has explicit template arguments
4295 (e.g. func<int>(5)), communicate this info to build_over_call
4296 through flags so that later we can use it to decide whether to warn
4297 about peculiar null pointer conversion. */
4299 {
4300 /* If overload resolution selects a specialization of a
4301 function concept for non-dependent template arguments,
4302 the expression is true if the constraints are satisfied
4303 and false otherwise.
4305 NOTE: This is an extension of Concepts Lite TS that
4306 allows constraints to be used in expressions. */
4308 {
4314 }
4317 }
4320 }
4322 /* Free all the conversions we allocated. */
4326 }
4328 /* Build a call to a global operator new. FNNAME is the name of the
4329 operator (either "operator new" or "operator new[]") and ARGS are
4330 the arguments provided. This may change ARGS. *SIZE points to the
4331 total number of bytes required by the allocation, and is updated if
4332 that is changed here. *COOKIE_SIZE is non-NULL if a cookie should
4333 be used. If this function determines that no cookie should be
4334 used, after all, *COOKIE_SIZE is set to NULL_TREE. If SIZE_CHECK
4335 is not NULL_TREE, it is evaluated before calculating the final
4336 array size, and if it fails, the array size is replaced with
4337 (size_t)-1 (usually triggering a std::bad_alloc exception). If FN
4338 is non-NULL, it will be set, upon return, to the allocation
4339 function called. */
4341 tree
4346 {
4348 tree fns;
4355 /* Set to (size_t)-1 if the size check fails. */
4357 {
4363 }
4369 /* Based on:
4371 [expr.new]
4373 If this lookup fails to find the name, or if the allocated type
4374 is not a class type, the allocation function's name is looked
4375 up in the global scope.
4377 we disregard block-scope declarations of "operator new". */
4382 {
4389 /* If no aligned allocation function matches, try again without the
4390 alignment. */
4391 }
4393 /* Figure out what function is being called. */
4396 complain);
4398 /* If no suitable function could be found, issue an error message
4399 and give up. */
4401 {
4405 }
4407 /* If a cookie is required, add some extra space. Whether
4408 or not a cookie is required cannot be determined until
4409 after we know which function was called. */
4411 {
4413 tree arg_types;
4416 /* Skip the size_t parameter. */
4418 /* Check the remaining parameters (if any). */
4422 ptr_type_node))
4424 /* If we need a cookie, adjust the number of bytes allocated. */
4426 {
4427 /* Update the total size. */
4430 {
4431 /* Set to (size_t)-1 if the size check fails. */
4435 }
4436 /* Update the argument list to reflect the adjusted size. */
4438 }
4439 else
4441 }
4443 /* Tell our caller which function we decided to call. */
4447 /* Build the CALL_EXPR. */
4449 }
4451 /* Build a new call to operator(). This may change ARGS. */
4453 static tree
4455 {
4472 {
4474 /* It's no good looking for an overloaded operator() on a
4475 pointer-to-member-function. */
4479 }
4482 {
4486 }
4487 else
4491 {
4495 }
4497 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4501 {
4509 }
4514 {
4522 {
4529 add_template_conv_candidate
4533 else
4537 }
4538 }
4540 /* Be strict here because if we choose a bad conversion candidate, the
4541 errors we get won't mention the call context. */
4544 {
4546 {
4550 }
4552 }
4553 else
4554 {
4557 {
4559 {
4563 }
4565 }
4570 else
4571 {
4575 else
4576 {
4579 }
4582 }
4583 }
4585 /* Free all the conversions we allocated. */
4589 }
4591 /* Wrapper for above. */
4593 tree
4595 {
4596 tree ret;
4601 }
4603 /* Called by op_error to prepare format strings suitable for the error
4604 function. It concatenates a prefix (controlled by MATCH), ERRMSG,
4605 and a suffix (controlled by NTYPES). */
4609 {
4619 else
4623 }
4625 static void
4628 {
4633 {
4639 else
4651 else
4661 else
4672 else
4682 else
4687 else
4691 else
4696 }
4697 }
4699 /* Return the implicit conversion sequence that could be used to
4700 convert E1 to E2 in [expr.cond]. */
4704 {
4710 /* [expr.cond]
4712 If E2 is an lvalue: E1 can be converted to match E2 if E1 can be
4713 implicitly converted (clause _conv_) to the type "lvalue reference to
4714 T2", subject to the constraint that in the conversion the
4715 reference must bind directly (_dcl.init.ref_) to an lvalue.
4717 If E2 is an xvalue: E1 can be converted to match E2 if E1 can be
4718 implicitly converted to the type "rvalue reference to T2", subject to
4719 the constraint that the reference must bind directly. */
4721 {
4724 t1,
4725 e1,
4727 LOOKUP_NO_TEMP_BIND|LOOKUP_NO_RVAL_BIND
4729 complain);
4732 }
4734 /* If E2 is a prvalue or if neither of the conversions above can be done
4735 and at least one of the operands has (possibly cv-qualified) class
4736 type: */
4740 /* [expr.cond]
4742 If E1 and E2 have class type, and the underlying class types are
4743 the same or one is a base class of the other: E1 can be converted
4744 to match E2 if the class of T2 is the same type as, or a base
4745 class of, the class of T1, and the cv-qualification of T2 is the
4746 same cv-qualification as, or a greater cv-qualification than, the
4747 cv-qualification of T1. If the conversion is applied, E1 is
4748 changed to an rvalue of type T2 that still refers to the original
4749 source class object (or the appropriate subobject thereof). */
4752 {
4754 {
4759 else
4762 }
4763 else
4765 }
4766 else
4767 /* [expr.cond]
4769 Otherwise: E1 can be converted to match E2 if E1 can be implicitly
4770 converted to the type that expression E2 would have if E2 were
4771 converted to an rvalue (or the type it has, if E2 is an rvalue). */
4774 }
4776 /* Implement [expr.cond]. ARG1, ARG2, and ARG3 are the three
4777 arguments to the conditional expression. */
4779 static tree
4781 tsubst_flags_t complain)
4782 {
4783 tree arg2_type;
4784 tree arg3_type;
4793 /* As a G++ extension, the second argument to the conditional can be
4794 omitted. (So that `a ? : c' is roughly equivalent to `a ? a :
4795 c'.) If the second operand is omitted, make sure it is
4796 calculated only once. */
4798 {
4806 /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */
4809 else
4811 }
4813 /* If something has already gone wrong, just pass that fact up the
4814 tree. */
4824 {
4827 /* If arg1 is another cond_expr choosing between -1 and 0,
4828 then we can use its comparison. It may help to avoid
4829 additional comparison, produce more accurate diagnostics
4830 and enables folding. */
4840 /* force_rvalue can return error_mark on valid arguments. */
4851 {
4852 /* Rely on the error messages of the scalar version. */
4861 {
4869 }
4873 /* We could pass complain & tf_warning to unsafe_conversion_p,
4874 but the warnings (like Wsign-conversion) have already been
4875 given by the scalar build_conditional_expr_1. We still check
4876 unsafe_conversion_p to forbid truncating long long -> float. */
4878 {
4883 }
4885 {
4890 }
4900 }
4903 {
4909 {
4913 {
4919 }
4921 {
4927 }
4930 }
4931 }
4937 {
4940 "incompatible vector types in conditional expression: "
4944 }
4947 {
4950 }
4952 }
4954 /* [expr.cond]
4956 The first expression is implicitly converted to bool (clause
4957 _conv_). */
4959 LOOKUP_NORMAL);
4963 /* [expr.cond]
4965 If either the second or the third operand has type (possibly
4966 cv-qualified) void, then the lvalue-to-rvalue (_conv.lval_),
4967 array-to-pointer (_conv.array_), and function-to-pointer
4968 (_conv.func_) standard conversions are performed on the second
4969 and third operands. */
4973 {
4974 /* Do the conversions. We don't these for `void' type arguments
4975 since it can't have any effect and since decay_conversion
4976 does not handle that case gracefully. */
4984 /* [expr.cond]
4986 One of the following shall hold:
4988 --The second or the third operand (but not both) is a
4989 throw-expression (_except.throw_); the result is of the
4990 type of the other and is an rvalue.
4992 --Both the second and the third operands have type void; the
4993 result is of type void and is an rvalue.
4995 We must avoid calling force_rvalue for expressions of type
4996 "void" because it will complain that their value is being
4997 used. */
5000 {
5002 {
5006 }
5009 }
5012 {
5014 {
5018 }
5021 }
5024 else
5025 {
5027 {
5030 "second operand to the conditional operator "
5031 "is of type %<void%>, but the third operand is "
5033 else
5035 "third operand to the conditional operator "
5036 "is of type %<void%>, but the second operand is "
5038 }
5040 }
5044 }
5045 /* [expr.cond]
5047 Otherwise, if the second and third operand have different types,
5048 and either has (possibly cv-qualified) class type, or if both are
5049 glvalues of the same value category and the same type except for
5050 cv-qualification, an attempt is made to convert each of those operands
5051 to the type of the other. */
5055 arg3_type)
5058 {
5063 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5069 /* [expr.cond]
5071 If both can be converted, or one can be converted but the
5072 conversion is ambiguous, the program is ill-formed. If
5073 neither can be converted, the operands are left unchanged and
5074 further checking is performed as described below. If exactly
5075 one conversion is possible, that conversion is applied to the
5076 chosen operand and the converted operand is used in place of
5077 the original operand for the remainder of this section. */
5082 {
5084 {
5091 else
5093 }
5095 }
5097 {
5101 /* Even if CONV2 is a valid conversion, the result of the
5102 conversion may be invalid. For example, if ARG3 has type
5103 "volatile X", and X does not have a copy constructor
5104 accepting a "volatile X&", then even if ARG2 can be
5105 converted to X, the conversion will fail. */
5109 }
5111 {
5118 }
5120 /* Free all the conversions we allocated. */
5126 /* If, after the conversion, both operands have class type,
5127 treat the cv-qualification of both operands as if it were the
5128 union of the cv-qualification of the operands.
5130 The standard is not clear about what to do in this
5131 circumstance. For example, if the first operand has type
5132 "const X" and the second operand has a user-defined
5133 conversion to "volatile X", what is the type of the second
5134 operand after this step? Making it be "const X" (matching
5135 the first operand) seems wrong, as that discards the
5136 qualification without actually performing a copy. Leaving it
5137 as "volatile X" seems wrong as that will result in the
5138 conditional expression failing altogether, even though,
5139 according to this step, the one operand could be converted to
5140 the type of the other. */
5148 }
5150 /* [expr.cond]
5152 If the second and third operands are glvalues of the same value
5153 category and have the same type, the result is of that type and
5154 value category. */
5158 {
5161 /* Let lvalue_kind know this was a glvalue. */
5167 }
5169 /* [expr.cond]
5171 Otherwise, the result is an rvalue. If the second and third
5172 operand do not have the same type, and either has (possibly
5173 cv-qualified) class type, overload resolution is used to
5174 determine the conversions (if any) to be applied to the operands
5175 (_over.match.oper_, _over.built_). */
5179 {
5184 /* Rearrange the arguments so that add_builtin_candidate only has
5185 to know about two args. In build_builtin_candidate, the
5186 arguments are unscrambled. */
5191 COND_EXPR,
5192 NOP_EXPR,
5194 args,
5197 /* [expr.cond]
5199 If the overload resolution fails, the program is
5200 ill-formed. */
5203 {
5208 }
5211 {
5213 {
5216 }
5218 }
5220 /* [expr.cond]
5222 Otherwise, the conversions thus determined are applied, and
5223 the converted operands are used in place of the original
5224 operands for the remainder of this section. */
5233 }
5235 /* [expr.cond]
5237 Lvalue-to-rvalue (_conv.lval_), array-to-pointer (_conv.array_),
5238 and function-to-pointer (_conv.func_) standard conversions are
5239 performed on the second and third operands.
5241 We need to force the lvalue-to-rvalue conversion here for class types,
5242 so we get TARGET_EXPRs; trying to deal with a COND_EXPR of class rvalues
5243 that isn't wrapped with a TARGET_EXPR plays havoc with exception
5244 regions. */
5257 /* [expr.cond]
5259 After those conversions, one of the following shall hold:
5261 --The second and third operands have the same type; the result is of
5262 that type. */
5265 /* [expr.cond]
5267 --The second and third operands have arithmetic or enumeration
5268 type; the usual arithmetic conversions are performed to bring
5269 them to a common type, and the result is of that type. */
5274 {
5275 /* In this case, there is always a common type. */
5277 arg3_type);
5280 "implicit conversion from %qH to %qI to "
5282 loc);
5286 {
5290 /* Two enumerators from the same enumeration can have different
5296 }
5303 {
5307 }
5311 }
5312 /* [expr.cond]
5314 --The second and third operands have pointer type, or one has
5315 pointer type and the other is a null pointer constant; pointer
5316 conversions (_conv.ptr_) and qualification conversions
5317 (_conv.qual_) are performed to bring them to their composite
5318 pointer type (_expr.rel_). The result is of the composite
5319 pointer type.
5321 --The second and third operands have pointer to member type, or
5322 one has pointer to member type and the other is a null pointer
5323 constant; pointer to member conversions (_conv.mem_) and
5324 qualification conversions (_conv.qual_) are performed to bring
5325 them to a common type, whose cv-qualification shall match the
5326 cv-qualification of either the second or the third operand.
5327 The result is of the common type. */
5335 {
5338 complain);
5343 }
5346 {
5351 }
5356 valid_operands:
5359 /* If the ARG2 and ARG3 are the same and don't have side-effects,
5360 warn here, because the COND_EXPR will be turned into ARG2. */
5367 /* We can't use result_type below, as fold might have returned a
5368 throw_expr. */
5371 {
5372 /* Expand both sides into the same slot, hopefully the target of
5373 the ?: expression. We used to check for TARGET_EXPRs here,
5374 but now we sometimes wrap them in NOP_EXPRs so the test would
5375 fail. */
5378 /* If this expression is an rvalue, but might be mistaken for an
5379 lvalue, we must add a NON_LVALUE_EXPR. */
5381 }
5382 else
5386 }
5388 /* Wrapper for above. */
5390 tree
5392 tsubst_flags_t complain)
5393 {
5394 tree ret;
5399 }
5401 /* OPERAND is an operand to an expression. Perform necessary steps
5402 required before using it. If OPERAND is NULL_TREE, NULL_TREE is
5403 returned. */
5405 static tree
5407 {
5409 {
5412 /* Make sure the template type is instantiated now. */
5414 }
5417 }
5419 /* Add each of the viable functions in FNS (a FUNCTION_DECL or
5420 OVERLOAD) to the CANDIDATES, returning an updated list of
5421 CANDIDATES. The ARGS are the arguments provided to the call;
5422 if FIRST_ARG is non-null it is the implicit object argument,
5423 otherwise the first element of ARGS is used if needed. The
5424 EXPLICIT_TARGS are explicit template arguments provided.
5425 TEMPLATE_ONLY is true if only template functions should be
5426 considered. CONVERSION_PATH, ACCESS_PATH, and FLAGS are as for
5427 add_function_candidate. */
5429 static void
5431 tree return_type,
5436 tsubst_flags_t complain)
5437 {
5438 tree ctype;
5442 unification_kind_t strict;
5447 /* Precalculate special handling of constructors and conversion ops. */
5450 {
5454 /* We're doing return_type(x). */
5456 else
5457 /* We're doing x.operator return_type(). */
5459 /* [over.match.funcs] For conversion functions, the function
5460 is considered to be a member of the class of the implicit
5461 object argument for the purpose of defining the type of
5462 the implicit object parameter. */
5464 }
5465 else
5466 {
5468 {
5470 /* For list-initialization we consider explicit constructors
5471 and complain if one is chosen. */
5472 check_converting
5475 }
5478 }
5482 else
5483 /* Delay creating the implicit this parameter until it is needed. */
5487 {
5499 {
5500 /* Figure out where the object arg comes from. If this
5501 function is a non-static member and we didn't get an
5502 implicit object argument, move it out of args. */
5504 {
5506 tree arg;
5513 }
5517 }
5521 fn,
5522 ctype,
5523 explicit_targs,
5524 fn_first_arg,
5525 fn_args,
5526 return_type,
5527 access_path,
5528 conversion_path,
5529 flags,
5530 strict,
5531 complain);
5534 fn,
5535 ctype,
5536 fn_first_arg,
5537 fn_args,
5538 access_path,
5539 conversion_path,
5540 flags,
5541 complain);
5542 }
5543 }
5545 /* Returns 1 if P0145R2 says that the LHS of operator CODE is evaluated first,
5546 -1 if the RHS is evaluated first, or 0 if the order is unspecified. */
5548 static int
5550 {
5552 {
5553 // 5. b @= a
5557 // 6. a[b]
5561 // 1. a.b
5562 // Not overloadable (yet).
5563 // 2. a->b
5564 // Only one argument.
5565 // 3. a->*b
5567 // 7. a << b
5569 // 8. a >> b
5575 }
5576 }
5578 static tree
5581 {
5602 {
5605 }
5612 {
5617 /* Use build_op_new_call and build_op_delete_call instead. */
5621 /* Use build_op_call instead. */
5628 /* These are saved for the sake of warn_logical_operator. */
5638 /* These are saved for the sake of maybe_warn_bool_compare. */
5643 /* =, ->, [], () must be non-static member functions. */
5647 /* FALLTHRU */
5655 }
5661 /* Use build_conditional_expr instead. */
5677 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5680 /* Add namespace-scope operators to the list of functions to
5681 consider. */
5683 {
5689 }
5695 /* Add class-member operators to the candidate set. */
5697 {
5698 tree fns;
5702 {
5705 }
5713 }
5714 /* Per 13.3.1.2/3, 2nd bullet, if no operand has a class type, then
5715 only non-member functions that have type T1 or reference to
5716 cv-qualified-opt T1 for the first argument, if the first argument
5717 has an enumeration type, or T2 or reference to cv-qualified-opt
5718 T2 for the second argument, if the second argument has an
5719 enumeration type. Filter out those that don't match. */
5721 {
5725 {
5735 {
5741 && (same_type_ignoring_top_level_qualifiers_p
5746 }
5748 /* No argument has an appropriate type, so remove this
5749 candidate function from the list. */
5751 {
5754 }
5755 }
5756 }
5762 {
5765 /* For these, the built-in candidates set is empty
5766 [over.match.oper]/3. We don't want non-strict matches
5767 because exact matches are always possible with built-in
5768 operators. The built-in candidate set for COMPONENT_REF
5769 would be empty too, but since there are no such built-in
5770 operators, we accept non-strict matches for them. */
5777 }
5781 {
5783 {
5786 /* Don't try anything fancy if we're not allowed to produce
5787 errors. */
5791 /* Look for an `operator++ (int)'. Pre-1985 C++ didn't
5792 distinguish between prefix and postfix ++ and
5793 operator++() was used for both, so we allow this with
5794 -fpermissive. */
5795 else
5796 {
5802 }
5809 else
5815 /* The caller will deal with these. */
5825 {
5826 /* If one of the arguments of the operator represents
5827 an invalid use of member function pointer, try to report
5828 a meaningful error ... */
5833 else
5834 {
5835 /* ... Otherwise, report the more generic
5836 "no matching operator found" error */
5839 }
5840 }
5843 }
5844 }
5845 else
5846 {
5849 {
5851 {
5854 }
5856 }
5858 {
5864 else
5870 {
5875 /* This prevents build_new_function_call from discarding this
5876 function during instantiation of the enclosing template. */
5879 /* Specify evaluation order as per P0145R2. */
5882 {
5893 }
5894 }
5895 }
5896 else
5897 {
5898 /* Give any warnings we noticed during overload resolution. */
5900 {
5904 }
5906 /* Check for comparison of different enum types. */
5908 {
5920 {
5924 }
5928 }
5930 /* We need to strip any leading REF_BIND so that bitfields
5931 don't cause errors. This should not remove any important
5932 conversions, because builtins don't apply to class
5933 objects directly. */
5940 {
5944 else
5947 /* We need to call warn_logical_operator before
5948 converting arg2 to a boolean_type, but after
5949 decaying an enumerator to its value. */
5956 }
5958 {
5963 }
5965 }
5966 }
5968 user_defined_result_ready:
5970 /* Free all the conversions we allocated. */
5976 builtin:
5978 {
5993 /* Fall through. */
6006 /* Fall through. */
6039 complain),
6042 /* The caller will deal with these. */
6050 }
6052 }
6054 /* Wrapper for above. */
6056 tree
6060 {
6061 tree ret;
6067 }
6069 /* CALL was returned by some call-building function; extract the actual
6070 CALL_EXPR from any bits that have been tacked on, e.g. by
6071 convert_from_reference. */
6073 tree
6075 {
6086 }
6088 /* Returns true if FN has two parameters, of which the second has type
6089 size_t. */
6091 static bool
6093 {
6105 }
6107 /* True if T, an allocation function, has std::align_val_t as its second
6108 argument. */
6110 bool
6112 {
6118 }
6120 /* Returns true iff T, an element of an OVERLOAD chain, is a usual deallocation
6121 function (3.7.4.2 [basic.stc.dynamic.deallocation]) with a parameter of
6122 std::align_val_t. */
6124 static bool
6126 {
6130 /* A template instance is never a usual deallocation function,
6131 regardless of its signature. */
6147 }
6149 /* Returns true iff T, an element of an OVERLOAD chain, is a usual
6150 deallocation function (3.7.4.2 [basic.stc.dynamic.deallocation]). */
6152 bool
6154 {
6155 /* A template instance is never a usual deallocation function,
6156 regardless of its signature. */
6161 /* If a class T has a member deallocation function named operator delete
6162 with exactly one parameter, then that function is a usual
6163 (non-placement) deallocation function. If class T does not declare
6164 such an operator delete but does declare a member deallocation
6165 function named operator delete with exactly two parameters, the second
6166 of which has type std::size_t (18.2), then this function is a usual
6167 deallocation function. */
6179 }
6181 /* Build a call to operator delete. This has to be handled very specially,
6182 because the restrictions on what signatures match are different from all
6183 other call instances. For a normal delete, only a delete taking (void *)
6184 or (void *, size_t) is accepted. For a placement delete, only an exact
6185 match with the placement new is accepted.
6187 CODE is either DELETE_EXPR or VEC_DELETE_EXPR.
6188 ADDR is the pointer to be deleted.
6189 SIZE is the size of the memory block to be deleted.
6190 GLOBAL_P is true if the delete-expression should not consider
6191 class-specific delete operators.
6192 PLACEMENT is the corresponding placement new call, or NULL_TREE.
6194 If this call to "operator delete" is being generated as part to
6195 deallocate memory allocated via a new-expression (as per [expr.new]
6196 which requires that if the initialization throws an exception then
6197 we call a deallocation function), then ALLOC_FN is the allocation
6198 function. */
6200 tree
6204 {
6218 /* In [class.free]
6220 If the result of the lookup is ambiguous or inaccessible, or if
6221 the lookup selects a placement deallocation function, the
6222 program is ill-formed.
6224 Therefore, we ask lookup_fnfields to complain about ambiguity. */
6225 {
6229 }
6230 else
6236 /* Strip const and volatile from addr. */
6240 {
6241 /* "A declaration of a placement deallocation function matches the
6242 declaration of a placement allocation function if it has the same
6243 number of parameters and, after parameter transformations (8.3.5),
6244 all parameter types except the first are identical."
6246 So we build up the function type we want and ask instantiate_type
6247 to get it for us. */
6258 /* "If the lookup finds the two-parameter form of a usual deallocation
6259 function (3.7.4.2) and that function, considered as a placement
6260 deallocation function, would have been selected as a match for the
6261 allocation function, the program is ill-formed." */
6263 {
6271 /* But if the class has an operator delete (void *), then that is
6272 the usual deallocation function, so we shouldn't complain
6273 about using the operator delete (void *, size_t). */
6277 {
6282 }
6283 /* Before C++14 a two-parameter global deallocation function is
6284 always a placement deallocation function, but warn if
6285 -Wc++14-compat. */
6287 {
6292 }
6295 {
6297 {
6298 /* Only mention C++14 for namespace-scope delete. */
6301 else
6303 "%qD is a usual (non-placement) deallocation "
6305 }
6306 }
6307 else
6309 ok:;
6310 }
6311 }
6312 else
6313 /* "Any non-placement deallocation function matches a non-placement
6314 allocation function. If the lookup finds a single matching
6315 deallocation function, that function will be called; otherwise, no
6316 deallocation function will be called." */
6318 {
6321 {
6323 {
6326 }
6328 /* -- If the type has new-extended alignment, a function with a
6329 parameter of type std::align_val_t is preferred; otherwise a
6330 function without such a parameter is preferred. If exactly one
6331 preferred function is found, that function is selected and the
6332 selection process terminates. If more than one preferred
6333 function is found, all non-preferred functions are eliminated
6334 from further consideration. */
6336 {
6342 {
6346 }
6347 }
6349 /* -- If the deallocation functions have class scope, the one
6350 without a parameter of type std::size_t is selected. */
6355 /* -- If the type is complete and if, for the second alternative
6356 (delete array) only, the operand is a pointer to a class type
6357 with a non-trivial destructor or a (possibly multi-dimensional)
6358 array thereof, the function with a parameter of type std::size_t
6359 is selected.
6361 -- Otherwise, it is unspecified whether a deallocation function
6362 with a parameter of type std::size_t is selected. */
6363 else
6364 {
6368 /* We need a cookie to determine the array size. */
6370 }
6376 }
6377 }
6379 /* If we have a matching function, call it. */
6381 {
6384 /* If the FN is a member function, make sure that it is
6385 accessible. */
6388 complain);
6390 /* Core issue 901: It's ok to new a type with deleted delete. */
6395 {
6396 /* The placement args might not be suitable for overload
6397 resolution at this point, so build the call directly. */
6407 }
6408 else
6409 {
6410 tree ret;
6416 {
6419 }
6423 }
6424 }
6426 /* [expr.new]
6428 If no unambiguous matching deallocation function can be found,
6429 propagating the exception does not cause the object's memory to
6430 be freed. */
6432 {
6436 alloc_fn);
6438 }
6444 }
6446 /* If the current scope isn't allowed to access DECL along
6447 BASETYPE_PATH, give an error. The most derived class in
6448 BASETYPE_PATH is the one used to qualify DECL. DIAG_DECL is
6449 the declaration to use in the error diagnostic. */
6451 bool
6454 {
6459 {
6460 /* 7.3.3/18: The additional constructors are accessible if they would be
6461 accessible when used to construct an object of the corresponding base
6462 class. */
6466 }
6469 {
6471 {
6475 {
6481 }
6483 {
6489 }
6490 else
6491 {
6496 }
6497 }
6499 }
6502 }
6504 /* Initialize a temporary of type TYPE with EXPR. The FLAGS are a
6505 bitwise or of LOOKUP_* values. If any errors are warnings are
6506 generated, set *DIAGNOSTIC_FN to "error" or "warning",
6507 respectively. If no diagnostics are generated, set *DIAGNOSTIC_FN
6508 to NULL. */
6510 static tree
6513 {
6519 /* If the source is a packed field, calling the copy constructor will require
6520 binding the field to the reference parameter to the copy constructor, and
6521 we'll end up with an infinite loop. If we can use a bitwise copy, then
6522 do that now. */
6538 }
6540 /* Perform warnings about peculiar, but valid, conversions from/to NULL.
6541 EXPR is implicitly converted to type TOTYPE.
6542 FN and ARGNUM are used for diagnostics. */
6544 static void
6546 {
6547 /* Issue warnings about peculiar, but valid, uses of NULL. */
6550 {
6551 source_location loc =
6558 else
6561 }
6563 /* Issue warnings if "false" is converted to a NULL pointer */
6566 {
6569 "converting %<false%> to pointer type for argument %P "
6571 else
6574 }
6575 }
6577 /* We gave a diagnostic during a conversion. If this was in the second
6578 standard conversion sequence of a user-defined conversion sequence, say
6579 which user-defined conversion. */
6581 static void
6583 {
6587 {
6591 }
6592 }
6594 /* Locate the parameter with the given index within FNDECL.
6595 ARGNUM is zero based, -1 indicates the `this' argument of a method.
6596 Return the location of the FNDECL itself if there are problems. */
6598 static location_t
6600 {
6602 tree param;
6604 /* Locate param by index within DECL_ARGUMENTS (fndecl). */
6608 ;
6610 /* If something went wrong (e.g. if we have a builtin and thus no arguments),
6611 return the location of FNDECL. */
6616 }
6618 /* Perform the conversions in CONVS on the expression EXPR. FN and
6619 ARGNUM are used for diagnostics. ARGNUM is zero based, -1
6620 indicates the `this' argument of a method. INNER is nonzero when
6621 being called to continue a conversion chain. It is negative when a
6622 reference binding will be applied, positive otherwise. If
6623 ISSUE_CONVERSION_WARNINGS is true, warnings about suspicious
6624 conversions will be emitted if appropriate. If C_CAST_P is true,
6625 this conversion is coming from a C-style cast; in that case,
6626 conversions to inaccessible bases are permitted. */
6628 static tree
6632 {
6634 diagnostic_t diag_kind;
6650 {
6654 /* Give a helpful error if this is bad because of excess braces. */
6659 {
6665 }
6667 /* Give a helpful error if this is bad because a conversion to bool
6668 from std::nullptr_t requires direct-initialization. */
6676 {
6678 {
6681 totype);
6687 complain);
6691 complain);
6692 else
6698 }
6700 {
6704 complain);
6706 }
6711 complain);
6714 }
6723 }
6729 {
6731 {
6735 /* We chose the surrogate function from add_conv_candidate, now we
6736 actually need to build the conversion. */
6742 /* When converting from an init list we consider explicit
6743 constructors, but actually trying to call one is an error. */
6746 /* Unless this is for direct-list-initialization. */
6748 /* And in C++98 a default constructor can't be explicit. */
6750 {
6756 {
6762 }
6763 else
6766 }
6768 /* If we're initializing from {}, it's value-initialization. */
6772 {
6779 {
6782 }
6784 }
6788 /* Pass LOOKUP_NO_CONVERSION so rvalue/base handling knows not to allow
6789 any more UDCs. */
6791 complain);
6793 /* If this is a constructor or a function returning an aggr type,
6794 we need to build up a TARGET_EXPR. */
6796 {
6799 /* Remember that this was list-initialization. */
6802 }
6805 }
6808 {
6814 else
6816 }
6825 /* If __null has been converted to an integer type, we do not want to
6826 continue to warn about uses of EXPR as an integer, rather than as a
6827 pointer. */
6831 /* We leave bad_p off ck_ambig because overload resolution considers
6832 it valid, it just fails when we try to perform it. So we need to
6833 check complain here, too. */
6835 {
6836 /* Call build_user_type_conversion again for the error. */
6844 }
6848 {
6849 /* Conversion to std::initializer_list<T>. */
6857 /* Convert all the elements. */
6859 {
6870 }
6871 /* Build up the array. */
6872 elttype = cp_build_qualified_type
6876 /* Take the address explicitly rather than via decay_conversion
6877 to avoid the error about taking the address of a temporary. */
6883 /* Build up the initializer_list object. Note: fail gracefully
6884 if the object cannot be completed because, for example, no
6885 definition is provided (c++/80956). */
6895 }
6899 {
6908 }
6911 complain);
6918 };
6928 {
6932 {
6934 {
6939 }
6941 }
6946 /* Don't introduce copies when passing arguments along to the inherited
6947 constructor. */
6949 && flag_new_inheriting_ctors
6955 /* Copy-list-initialization doesn't actually involve a copy. */
6958 /* Fall through. */
6961 {
6962 /* We are going to bind a reference directly to a base-class
6963 subobject of EXPR. */
6964 /* Build an expression for `*((base*) &expr)'. */
6968 }
6970 /* Copy-initialization where the cv-unqualified version of the source
6971 type is the same class as, or a derived class of, the class of the
6972 destination [is treated as direct-initialization]. [dcl.init] */
6975 /* This conversion is being done in the context of a user-defined
6976 conversion (i.e. the second step of copy-initialization), so
6977 don't allow any more. */
6979 else
6982 /* standard_conversion got LOOKUP_PREFER_RVALUE. */
6986 {
6991 }
6996 {
7000 {
7013 else
7020 }
7022 /* If necessary, create a temporary.
7024 VA_ARG_EXPR and CONSTRUCTOR expressions are special cases
7025 that need temporaries, even when their types are reference
7026 compatible with the type of reference being bound, so the
7027 upcoming call to cp_build_addr_expr doesn't fail. */
7031 {
7032 /* Otherwise, a temporary of type "cv1 T1" is created and
7033 initialized from the initializer expression using the rules
7034 for a non-reference copy-initialization (8.5). */
7043 {
7044 /* If the reference is volatile or non-const, we
7045 cannot create a temporary. */
7052 else
7056 }
7057 /* If the source is a packed field, and we must use a copy
7058 constructor, then building the target expr will require
7059 binding the field to the reference parameter to the
7060 copy constructor, and we'll end up with an infinite
7061 loop. If we can use a bitwise copy, then we'll be
7062 OK. */
7066 {
7070 }
7072 {
7075 }
7077 }
7079 /* Take the address of the thing to which we will bind the
7080 reference. */
7085 /* Convert it to a pointer to the type referred to by the
7086 reference. This will adjust the pointer if a derived to
7087 base conversion is being performed. */
7090 /* Convert the pointer to the desired reference type. */
7092 }
7098 /* ??? Should the address of a transaction-safe pointer point to the TM
7099 clone, and this conversion look up the primary function? */
7103 /* Warn about deprecated conversion if appropriate. */
7119 }
7127 else
7131 }
7133 /* ARG is being passed to a varargs function. Perform any conversions
7134 required. Return the converted value. */
7136 tree
7138 {
7139 tree arg_type;
7142 /* [expr.call]
7144 The lvalue-to-rvalue, array-to-pointer, and function-to-pointer
7145 standard conversions are performed. */
7148 /* [expr.call]
7150 If the argument has integral or enumeration type that is subject
7151 to the integral promotions (_conv.prom_), or a floating point
7152 type that is subject to the floating point promotion
7153 (_conv.fpprom_), the value of the argument is converted to the
7154 promoted type before the call. */
7159 {
7163 "implicit conversion from %qH to %qI when passing "
7167 }
7171 {
7173 {
7175 complain);
7185 }
7186 else
7188 }
7194 /* In a template (or ill-formed code), we can have an incomplete type
7195 even after require_complete_type_sfinae, in which case we don't know
7196 whether it has trivial copy or not. */
7199 {
7200 /* [expr.call] 5.2.2/7:
7201 Passing a potentially-evaluated argument of class type (Clause 9)
7202 with a non-trivial copy constructor or a non-trivial destructor
7203 with no corresponding parameter is conditionally-supported, with
7204 implementation-defined semantics.
7206 We support it as pass-by-invisible-reference, just like a normal
7207 value parameter.
7209 If the call appears in the context of a sizeof expression,
7210 it is not potentially-evaluated. */
7213 {
7217 "passing objects of non-trivially-copyable "
7219 arg_type);
7221 }
7222 /* Build up a real lvalue-to-rvalue conversion in case the
7223 copy constructor is trivial but not callable. */
7227 }
7230 }
7232 /* va_arg (EXPR, TYPE) is a builtin. Make sure it is not abused. */
7234 tree
7236 {
7238 {
7242 }
7252 {
7255 }
7259 {
7260 /* conditionally-supported behavior [expr.call] 5.2.2/7. Let's treat
7261 it as pass by invisible reference. */
7263 "receiving objects of non-trivially-copyable type %q#T "
7269 }
7273 /* Wrap the VA_ARG_EXPR in a TARGET_EXPR now so other code doesn't need to
7274 know how to handle it. */
7277 }
7279 /* TYPE has been given to va_arg. Apply the default conversions which
7280 would have happened when passed via ellipsis. Return the promoted
7281 type, or the passed type if there is no change. */
7283 tree
7285 {
7286 tree promote;
7288 /* Perform the array-to-pointer and function-to-pointer
7289 conversions. */
7297 }
7299 /* ARG is a default argument expression being passed to a parameter of
7300 the indicated TYPE, which is a parameter to FN. PARMNUM is the
7301 zero-based argument number. Do any required conversions. Return
7302 the converted value. */
7305 void
7309 void
7313 tree
7315 tsubst_flags_t complain)
7316 {
7318 tree t;
7320 /* See through clones. */
7322 /* And inheriting ctors. */
7326 /* Detect recursion. */
7329 {
7333 }
7335 /* If the ARG is an unparsed default argument expression, the
7336 conversion cannot be performed. */
7338 {
7343 }
7350 /* Due to:
7352 [dcl.fct.default]
7354 The names in the expression are bound, and the semantic
7355 constraints are checked, at the point where the default
7356 expressions appears.
7358 we must not perform access checks here. */
7360 /* We must make a copy of ARG, in case subsequent processing
7361 alters any part of it. */
7365 complain);
7372 }
7374 /* Returns the type which will really be used for passing an argument of
7375 type TYPE. */
7377 tree
7379 {
7380 /* Pass classes with copy ctors by invisible reference. */
7382 {
7384 /* There are no other pointers to this temporary. */
7386 }
7394 }
7396 /* Actually perform the appropriate conversion. */
7398 tree
7400 {
7401 tree bitfield_type;
7403 /* If VAL is a bitfield, then -- since it has already been converted
7404 to TYPE -- it cannot have a precision greater than TYPE.
7406 If it has a smaller precision, we must widen it here. For
7407 example, passing "int f:3;" to a function expecting an "int" will
7408 not result in any conversion before this point.
7410 If the precision is the same we must not risk widening. For
7411 example, the COMPONENT_REF for a 32-bit "long long" bitfield will
7412 often have type "int", even though the C++ type for the field is
7413 "long long". If the value is being passed to a function
7414 expecting an "int", then no conversions will be required. But,
7415 if we call convert_bitfield_to_declared_type, the bitfield will
7416 be converted to "long long". */
7423 ;
7424 /* Pass classes with copy ctors by invisible reference. */
7433 {
7435 {
7443 "argument of function call might be a candidate "
7445 }
7447 }
7449 }
7451 /* Returns non-zero iff FN is a function with magic varargs, i.e. ones for
7452 which just decay_conversion or no conversions at all should be done.
7453 This is true for some builtins which don't act like normal functions.
7454 Return 2 if no conversions at all should be done, 1 if just
7455 decay_conversion. Return 3 for special treatment of the 3rd argument
7456 for __builtin_*_overflow_p. */
7458 int
7460 {
7463 {
7478 }
7481 }
7483 /* Returns the decl of the dispatcher function if FN is a function version. */
7485 tree
7487 {
7497 {
7501 }
7506 }
7508 /* fn is a function version dispatcher that is marked used. Mark all the
7509 semantically identical function versions it will dispatch as used. */
7511 void
7513 {
7530 /* All semantically identical versions are chained. Traverse and mark each
7531 one of them as used. */
7534 {
7537 }
7538 }
7540 /* Build a call to "the copy constructor" for the type of A, even if it
7541 wouldn't be selected by normal overload resolution. Used for
7542 diagnostics. */
7544 static tree
7546 {
7557 }
7559 /* Return true iff T refers to a base field. */
7561 static bool
7563 {
7572 }
7574 /* We can't elide a copy from a function returning by value to a base
7575 subobject, as the callee might clobber tail padding. Return true iff this
7576 could be that case. */
7578 static bool
7580 {
7581 /* Copy elision only happens with a TARGET_EXPR. */
7585 /* It's safe to elide the copy for a class with no tail padding. */
7588 /* It's safe to elide the copy if we aren't initializing a base object. */
7592 /* build_compound_expr pushes COMPOUND_EXPR inside TARGET_EXPR. */
7596 {
7597 /* We'll end up copying from each of the arms of the COND_EXPR directly
7598 into the target, so look at them. */
7603 }
7606 }
7608 /* True iff C is a conversion that binds a reference to a prvalue. */
7610 static bool
7612 {
7629 }
7631 /* Subroutine of the various build_*_call functions. Overload resolution
7632 has chosen a winning candidate CAND; build up a CALL_EXPR accordingly.
7633 ARGS is a TREE_LIST of the unconverted arguments to the call. FLAGS is a
7634 bitmask of various LOOKUP_* flags which apply to the call itself. */
7636 static tree
7638 {
7646 tree val;
7655 /* In a template, there is no need to perform all of the work that
7656 is normally done. We are only interested in the type of the call
7657 expression, i.e., the return type of the function. Any semantic
7658 errors will be deferred until the template is instantiated. */
7660 {
7662 tree return_type;
7668 else
7669 /* Otherwise set TREE_USED for the benefit of -Wunused-function.
7670 See PR80598. */
7677 else
7678 {
7681 tree arg;
7689 }
7699 }
7701 /* Give any warnings we noticed during overload resolution. */
7703 {
7707 }
7709 /* Core issue 2327: P0135 doesn't say how to handle the case where the
7710 argument to the copy constructor ends up being a prvalue after
7711 conversion. Let's do the normal processing, but pretend we aren't
7712 actually using the copy constructor. */
7720 {
7723 }
7725 /* OK, we're actually calling this inherited constructor; set its deletedness
7726 appropriately. We can get away with doing this here because calling is
7727 the only way to refer to a constructor. */
7731 /* Make =delete work with SFINAE. */
7733 {
7737 }
7740 {
7741 tree access_fn;
7742 /* If FN is a template function, two cases must be considered.
7743 For example:
7745 struct A {
7746 protected:
7747 template <class T> void f();
7748 };
7749 template <class T> struct B {
7750 protected:
7751 void g();
7752 };
7753 struct C : A, B<int> {
7754 using A::f; // #1
7755 using B<int>::g; // #2
7756 };
7758 In case #1 where `A::f' is a member template, DECL_ACCESS is
7759 recorded in the primary template but not in its specialization.
7760 We check access of FN using its primary template.
7762 In case #2, where `B<int>::g' has a DECL_TEMPLATE_INFO simply
7763 because it is a member of class template B, DECL_ACCESS is
7764 recorded in the specialization `B<int>::g'. We cannot use its
7765 primary template because `B<T>::g' and `B<int>::g' may have
7766 different access. */
7770 else
7775 }
7777 /* If we're checking for implicit delete, don't bother with argument
7778 conversions. */
7780 {
7784 /* Reject bad conversions now. */
7786 /* else continue to get conversion error. */
7787 }
7789 not_really_used:
7791 /* N3276 magic doesn't apply to nested calls. */
7794 /* No-Cleanup doesn't apply to nested calls either. */
7798 /* Find maximum size of vector to hold converted arguments. */
7805 /* The implicit parameters to a constructor are not considered by overload
7806 resolution, and must be of the proper type. */
7808 {
7809 tree object_arg;
7811 {
7814 }
7815 else
7816 {
7819 }
7822 /* We should never try to call the abstract constructor. */
7826 {
7830 }
7833 {
7834 /* The implicit move specified in 15.8.3/3 fails "...if the type of
7835 the first parameter of the selected constructor is not an rvalue
7836 reference to the object’s type (possibly cv-qualified)...." */
7843 }
7844 }
7845 /* Bypass access control for 'this' parameter. */
7847 {
7850 ? first_arg
7853 tree converted_arg;
7854 tree base_binfo;
7860 {
7862 {
7867 }
7868 else
7870 }
7872 /* See if the function member or the whole class type is declared
7873 final and the call can be devirtualized. */
7878 /* [class.mfct.nonstatic]: If a nonstatic member function of a class
7879 X is called for an object that is not of type X, or of a type
7880 derived from X, the behavior is undefined.
7882 So we can assume that anything passed as 'this' is non-null, and
7883 optimize accordingly. */
7885 /* Convert to the base in which the function was declared. */
7888 arg,
7891 /* Check that the base class is accessible. */
7894 {
7899 else
7901 }
7902 /* If fn was found by a using declaration, the conversion path
7903 will be to the derived class, not the base declaring fn. We
7904 must convert from derived to base. */
7915 else
7919 }
7924 {
7931 /* If the argument is NULL and used to (implicitly) instantiate a
7932 template function (and bind one of the template arguments to
7933 the type of 'long int'), we don't want to warn about passing NULL
7934 to non-pointer argument.
7935 For example, if we have this template function:
7937 template<typename T> void func(T x) {}
7939 we want to warn (when -Wconversion is enabled) in this case:
7941 void foo() {
7942 func<int>(NULL);
7943 }
7945 but not in this case:
7947 void foo() {
7948 func(NULL);
7949 }
7950 */
7957 /* Warn about initializer_list deduction that isn't currently in the
7958 working draft. */
7960 && flag_deduce_init_list
7964 {
7977 {
7985 }
7986 }
7988 /* Set user_conv_p on the argument conversions, so rvalue/base handling
7989 knows not to allow any more UDCs. This needs to happen after we
7990 process cand->warnings. */
7999 arg_complain);
8004 else
8006 }
8008 /* Default arguments */
8010 {
8016 complain);
8020 }
8022 /* Ellipsis */
8025 {
8028 {
8029 /* Do no conversions for certain magic varargs. */
8033 }
8035 /* For other magic varargs only do decay_conversion. */
8040 {
8041 /* Avoid infinite recursion trying to call A(...). */
8043 /* Try to call the actual copy constructor for a good error. */
8046 }
8047 else
8052 }
8057 /* Avoid to do argument-transformation, if warnings for format, and for
8058 nonnull are disabled. Just in case that at least one of them is active
8059 the check_function_arguments function might warn about something. */
8063 || warn_format
8064 || warn_suggest_attribute_format
8066 {
8070 {
8071 /* For -Wformat undo the implicit passing by hidden reference
8072 done by convert_arg_to_ellipsis. */
8076 else
8078 }
8082 }
8085 {
8086 /* Check for passing ellipsis arguments to an inherited constructor. We
8087 could handle this by open-coding the inherited constructor rather than
8088 defining it, but let's not bother now. */
8092 {
8094 {
8098 }
8100 }
8102 /* A base constructor inheriting from a virtual base doesn't get the
8103 inherited arguments, just this and __vtt. */
8106 }
8108 /* Avoid actually calling copy constructors and copy assignment operators,
8109 if possible. */
8116 /* It's unsafe to elide the constructor when handling
8117 a noexcept-expression, it may evaluate to the wrong
8118 value (c++/53025). */
8120 {
8121 tree targ;
8123 tree fa;
8126 /* Pull out the real argument, disregarding const-correctness. */
8128 /* Strip the reference binding for the constructor parameter. */
8132 /* But don't strip any other reference bindings; binding a temporary to a
8133 reference prevents copy elision. */
8139 {
8144 }
8145 else
8150 else
8153 /* In C++17 we shouldn't be copying a TARGET_EXPR except into a base
8154 subobject. */
8157 || force_elide
8158 /* It's from binding the ref parm to a packed field. */
8161 /* See unsafe_copy_elision_p. */
8164 /* [class.copy]: the copy constructor is implicitly defined even if
8165 the implementation elided its use. */
8167 {
8171 }
8173 /* If we're creating a temp and we already have one, don't create a
8174 new one. If we're not creating a temp but we get one, use
8175 INIT_EXPR to collapse the temp into our target. Otherwise, if the
8176 ctor is trivial, do a bitwise copy with a simple TARGET_EXPR for a
8177 temp or an INIT_EXPR otherwise. */
8180 {
8185 }
8188 {
8193 }
8194 }
8198 {
8199 tree to = cp_stabilize_reference
8206 {
8207 /* Avoid copying empty classes. */
8210 }
8212 {
8215 }
8216 else
8217 {
8218 /* We must only copy the non-tail padding parts. */
8226 build_index_type
8235 }
8238 }
8240 {
8244 {
8247 no_cleanup_complain);
8248 else
8250 }
8251 }
8259 /* Warn if the built-in writes to an object of a non-trivial type. */
8266 /* Don't mess with virtual lookup in instantiate_non_dependent_expr;
8267 virtual functions can't be constexpr. */
8269 {
8270 tree t;
8277 complain);
8283 }
8284 else
8285 {
8289 }
8295 {
8297 /* build_new_op_1 will clear this when appropriate. */
8299 }
8301 {
8305 }
8307 }
8309 namespace
8310 {
8312 /* Return the DECL of the first non-static subobject of class TYPE
8313 that satisfies the predicate PRED or null if none can be found. */
8316 tree
8318 {
8323 {
8330 }
8336 {
8342 }
8345 }
8347 struct NonPublicField
8348 {
8350 {
8352 }
8353 };
8355 /* Return the DECL of the first non-public subobject of class TYPE
8356 or null if none can be found. */
8360 {
8362 }
8364 struct NonTrivialField
8365 {
8367 {
8369 }
8370 };
8372 /* Return the DECL of the first non-trivial subobject of class TYPE
8373 or null if none can be found. */
8377 {
8379 }
8383 /* Return true if all copy and move assignment operator overloads for
8384 class TYPE are trivial and at least one of them is not deleted and,
8385 when ACCESS is set, accessible. Return false otherwise. Set
8386 HASASSIGN to true when the TYPE has a (not necessarily trivial)
8387 copy or move assignment. */
8389 static bool
8391 {
8395 /* Iterate over overloads of the assignment operator, checking
8396 accessible copy assignments for triviality. */
8399 {
8402 /* Skip operators that aren't copy assignments. */
8409 /* Skip template assignment operators and deleted functions. */
8419 /* Break early when both properties have been determined. */
8422 }
8424 /* Return true if they're all trivial and one of the expressions
8425 TYPE() = TYPE() or TYPE() = (TYPE&)() is valid. */
8430 }
8432 /* Return true if all copy and move ctor overloads for class TYPE are
8433 trivial and at least one of them is not deleted and, when ACCESS is
8434 set, accessible. Return false otherwise. Set each element of HASCTOR[]
8435 to true when the TYPE has a (not necessarily trivial) default and copy
8436 (or move) ctor, respectively. */
8438 static bool
8440 {
8445 {
8448 /* Skip template constructors. */
8454 /* Skip ctors other than default, copy, and move. */
8470 /* Break early when both properties have been determined. */
8473 }
8476 }
8478 /* Issue a warning on a call to the built-in function FNDECL if it is
8479 a raw memory write whose destination is not an object of (something
8480 like) trivial or standard layout type with a non-deleted assignment
8481 and copy ctor. Detects const correctness violations, corrupting
8482 references, virtual table pointers, and bypassing non-trivial
8483 assignments. */
8485 static void
8488 {
8489 /* Except for bcopy where it's second, the destination pointer is
8490 the first argument for all functions handled here. Compute
8491 the index of the destination and source arguments. */
8501 /* Determine the type of the pointed-to object and whether it's
8502 a complete class type. */
8508 /* Check to see if the raw memory call is made by a non-static member
8509 function with THIS as the destination argument for the destination
8510 type. If so, and if the class has no non-trivial bases or members,
8511 be more permissive. */
8515 {
8520 /* FIXME: The following if statement is overly permissive (see
8521 bug 84851). Remove it in GCC 9. */
8533 }
8535 /* True if the class is trivial. */
8538 /* Set to true if DESTYPE has an accessible copy assignment. */
8540 /* True if all of the class' overloaded copy assignment operators
8541 are all trivial (and not deleted) and at least one of them is
8542 accessible. */
8545 /* Set to true if DESTTYPE has an accessible default and copy ctor,
8546 respectively. */
8549 /* True if all of the class' overloaded copy constructors are all
8550 trivial (and not deleted) and at least one of them is accessible. */
8553 /* Set FLD to the first private/protected member of the class. */
8556 /* The warning format string. */
8558 /* A suggested alternative to offer instead of the raw memory call.
8559 Empty string when none can be come up with. */
8564 {
8567 {
8568 /* Diagnose setting non-copy-assignable or non-trivial types,
8569 or types with a private member, to (potentially) non-zero
8570 bytes. Since the value of the bytes being written is unknown,
8571 suggest using assignment instead (if one exists). Also warn
8572 for writes into objects for which zero-initialization doesn't
8573 mean all bits clear (pointer-to-member data, where null is all
8574 bits set). Since the value being written is (most likely)
8575 non-zero, simply suggest assignment (but not copy assignment). */
8583 {
8586 "%qD writing to an object of type %#qT with "
8589 }
8595 }
8596 /* Fall through. */
8599 /* Similarly to the above, diagnose clearing non-trivial or non-
8600 standard layout objects, or objects of types with no assignmenmt.
8601 Since the value being written is known to be zero, suggest either
8602 copy assignment, copy ctor, or default ctor as an alternative,
8603 depending on what's available. */
8626 /* Determine the type of the source object. */
8630 else
8633 /* Since it's impossible to determine wheter the byte copy is
8634 being used in place of assignment to an existing object or
8635 as a substitute for initialization, assume it's the former.
8636 Determine the best alternative to use instead depending on
8637 what's not deleted. */
8658 srctype))
8659 {
8660 /* Warn when copying into a non-trivial object from an object
8661 of a different type other than void or char. */
8663 "%qD copying an object of non-trivial type "
8666 }
8671 srctype))
8672 {
8675 "%qD copying an object of type %#qT with "
8676 "%qs member %qD from an array of %#qT; use "
8679 }
8681 {
8686 /* Finally, warn on partial copies. */
8687 unsigned HOST_WIDE_INT typesize
8693 "a non-trivial type %#qT leaves %wu "
8696 "a non-trivial type %#qT leaves %wu "
8699 }
8714 {
8718 /* Finally, warn on reallocation into insufficient space. */
8720 "%qD moving an object of non-trivial type "
8723 sz);
8724 }
8729 }
8732 {
8736 else
8739 }
8743 }
8745 /* Build and return a call to FN, using NARGS arguments in ARGARRAY.
8746 This function performs no overload resolution, conversion, or other
8747 high-level operations. */
8749 tree
8751 tsubst_flags_t complain)
8752 {
8753 tree fndecl;
8755 /* Remember roughly where this call is. */
8762 /* Check that arguments to builtin functions match the expectations. */
8766 {
8769 /* We need to take care that values to BUILT_IN_NORMAL
8770 are reduced. */
8777 }
8782 /* 5.2.2/11: If a function call is a prvalue of object type: if the
8783 function call is either the operand of a decltype-specifier or the
8784 right operand of a comma operator that is the operand of a
8785 decltype-specifier, a temporary object is not introduced for the
8786 prvalue. The type of the prvalue may be incomplete. */
8788 {
8794 {
8797 }
8798 }
8800 }
8802 /* Returns the value to use for the in-charge parameter when making a
8803 call to a function with the indicated NAME.
8805 FIXME:Can't we find a neater way to do this mapping? */
8807 tree
8809 {
8811 {
8815 }
8816 else
8817 {
8823 }
8826 }
8828 /* We've built up a constructor call RET. Complain if it delegates to the
8829 constructor we're currently compiling. */
8831 static void
8833 {
8839 }
8841 /* Build a call to a constructor, destructor, or an assignment
8842 operator for INSTANCE, an expression with class type. NAME
8843 indicates the special member function to call; *ARGS are the
8844 arguments. ARGS may be NULL. This may change ARGS. BINFO
8845 indicates the base of INSTANCE that is to be passed as the `this'
8846 parameter to the member function called.
8848 FLAGS are the LOOKUP_* flags to use when processing the call.
8850 If NAME indicates a complete object constructor, INSTANCE may be
8851 NULL_TREE. In this case, the caller will call build_cplus_new to
8852 store the newly constructed object into a VAR_DECL. */
8854 tree
8857 {
8858 tree fns;
8859 /* The type of the subobject to be constructed or destroyed. */
8860 tree class_type;
8862 tree ret;
8866 {
8867 /* Resolve the name. */
8872 }
8878 /* Handle the special case where INSTANCE is NULL_TREE. */
8881 else
8882 {
8886 /* Convert to the base class, if necessary. */
8889 {
8891 /* For constructors and destructors, either the base is
8892 non-virtual, or it is virtual but we are doing the
8893 conversion from a constructor or destructor for the
8894 complete object. In either case, we can convert
8895 statically. */
8897 else
8898 {
8899 /* However, for assignment operators, we must convert
8900 dynamically if the base is virtual. */
8904 }
8905 }
8906 }
8910 /* In C++17, "If the initializer expression is a prvalue and the
8911 cv-unqualified version of the source type is the same class as the class
8912 of the destination, the initializer expression is used to initialize the
8913 destination object." Handle that here to avoid doing overload
8914 resolution. */
8918 {
8928 && (same_type_ignoring_top_level_qualifiers_p
8930 {
8939 /* Avoid change of behavior on Wunused-var-2.C. */
8942 }
8943 }
8947 /* When making a call to a constructor or destructor for a subobject
8948 that uses virtual base classes, pass down a pointer to a VTT for
8949 the subobject. */
8953 {
8954 tree vtt;
8955 tree sub_vtt;
8957 /* If the current function is a complete object constructor
8958 or destructor, then we fetch the VTT directly.
8959 Otherwise, we look it up using the VTT we were given. */
8967 else
8971 {
8974 }
8977 }
8982 complain);
8993 }
8995 /* Return the NAME, as a C string. The NAME indicates a function that
8996 is a member of TYPE. *FREE_P is set to true if the caller must
8997 free the memory returned.
8999 Rather than go through all of this, we should simply set the names
9000 of constructors and destructors appropriately, and dispense with
9001 ctor_identifier, dtor_identifier, etc. */
9005 {
9008 /* Assume that we will not allocate memory. */
9010 /* Constructors and destructors are special. */
9012 {
9013 pretty_name
9015 /* For a destructor, add the '~'. */
9017 {
9019 /* Remember that we need to free the memory allocated. */
9021 }
9022 }
9024 {
9027 TFF_PLAIN_IDENTIFIER),
9028 NULL);
9029 /* Remember that we need to free the memory allocated. */
9031 }
9032 else
9036 }
9038 /* Build a call to "INSTANCE.FN (ARGS)". If FN_P is non-NULL, it will
9039 be set, upon return, to the function called. ARGS may be NULL.
9040 This may change ARGS. */
9042 static tree
9046 {
9051 tree optype;
9053 tree name;
9056 tree call;
9057 tree fn;
9060 tree orig_instance;
9061 tree orig_fns;
9067 /* We don't know what function we're going to call, yet. */
9076 {
9080 }
9085 /* Dismantle the baselink to collect all the information we need. */
9093 {
9097 }
9108 /* Under DR 147 A::A() is an invalid constructor call,
9109 not a functional cast. */
9111 {
9123 complain);
9125 }
9128 {
9133 }
9135 /* Process the argument list. */
9137 {
9142 }
9144 /* Consider the object argument to be used even if we end up selecting a
9145 static member function. */
9148 /* Figure out whether to skip the first argument for the error
9149 message we will display to users if an error occurs. We don't
9150 want to display any compiler-generated arguments. The "this"
9151 pointer hasn't been added yet. However, we must remove the VTT
9152 pointer if this is a call to a base-class constructor or
9153 destructor. */
9156 {
9157 /* Callers should explicitly indicate whether they want to ctor
9158 the complete object or just the part without virtual bases. */
9161 /* Remove the VTT pointer, if present. */
9166 /* It's OK to call destructors and constructors on cv-qualified
9167 objects. Therefore, convert the INSTANCE to the unqualified
9168 type, if necessary. */
9170 {
9174 }
9175 }
9176 else
9179 /* For the overload resolution we need to find the actual `this`
9180 that would be captured if the call turns out to be to a
9181 non-static member function. Do not actually capture it at this
9182 point. */
9184 /* Constructors don't use the enclosing 'this'. */
9186 else
9189 /* Get the high-water mark for the CONVERSION_OBSTACK. */
9192 /* The number of arguments artificial parms in ARGS; we subtract one because
9193 there's no 'this' in ARGS. */
9196 /* If CONSTRUCTOR_IS_DIRECT_INIT is set, this was a T{ } form
9197 initializer, not T({ }). */
9201 {
9208 /* If the initializer list has no elements and T is a class type with
9209 a default constructor, the object is value-initialized. Handle
9210 this here so we don't need to handle it wherever we use
9211 build_special_member_call. */
9214 /* For a user-provided default constructor, use the normal
9215 mechanisms so that protected access works. */
9220 /* If BASETYPE is an aggregate, we need to do aggregate
9221 initialization. */
9223 {
9226 }
9229 {
9235 }
9237 /* Otherwise go ahead with overload resolution. */
9242 }
9243 else
9252 {
9254 {
9261 else
9262 {
9267 {
9270 }
9278 }
9280 }
9282 }
9283 else
9284 {
9287 {
9290 tree arglist;
9293 {
9301 else
9307 }
9309 }
9310 else
9311 {
9319 {
9320 /* This is not an error, it is runtime undefined
9321 behavior. */
9330 fn);
9331 }
9336 {
9341 {
9342 /* We captured 'this' in the current lambda now that
9343 we know we really need it. */
9345 }
9347 /* We can't tell until instantiation time whether we can use
9349 else
9350 {
9353 fn);
9355 }
9356 }
9359 {
9360 /* Optimize away vtable lookup if we know that this
9361 function can't be overridden. We need to check if
9362 the context and the type where we found fn are the same,
9363 actually FN might be defined in a different class
9364 type because of a using-declaration. In this case, we
9365 do not want to perform a non-virtual call. */
9367 && same_type_ignoring_top_level_qualifiers_p
9373 /* Now we know what function is being called. */
9376 /* Build the actual CALL_EXPR. */
9378 /* In an expression of the form `a->f()' where `f' turns
9379 out to be a static member function, `a' is
9380 none-the-less evaluated. */
9384 {
9385 /* But avoid the implicit lvalue-rvalue conversion when 'a'
9386 is volatile. */
9391 }
9395 /* An explicit call of the form "x->~X()" has type
9396 "void". However, on platforms where destructors
9397 return "this" (i.e., those where
9398 targetm.cxx.cdtor_returns_this is true), such calls
9399 will appear to have a return value of pointer type
9400 to the low-level call machinery. We do not want to
9401 change the low-level machinery, since we want to be
9402 able to optimize "delete f()" on such platforms as
9403 "operator delete(~X(f()))" (rather than generating
9404 "t = f(), ~X(t), operator delete (t)"). */
9406 }
9407 }
9408 }
9411 {
9417 {
9420 }
9423 call = (build_min_non_dep_call_vec
9427 orig_args));
9432 }
9434 /* Free all the conversions we allocated. */
9441 }
9443 /* Wrapper for above. */
9445 tree
9449 {
9450 tree ret;
9456 }
9458 /* Returns true iff standard conversion sequence ICS1 is a proper
9459 subsequence of ICS2. */
9461 static bool
9463 {
9464 /* We can assume that a conversion of the same code
9465 between the same types indicates a subsequence since we only get
9466 here if the types we are converting from are the same. */
9473 {
9483 /* At this point, ICS1 cannot be a proper subsequence of
9484 ICS2. We can get a USER_CONV when we are comparing the
9485 second standard conversion sequence of two user conversion
9486 sequences. */
9501 }
9502 }
9504 /* Returns nonzero iff DERIVED is derived from BASE. The inputs may
9505 be any _TYPE nodes. */
9507 bool
9509 {
9513 /* We only allow proper derivation here. The DERIVED_FROM_P macro
9514 considers every class derived from itself. */
9517 }
9519 /* We build the ICS for an implicit object parameter as a pointer
9520 conversion sequence. However, such a sequence should be compared
9521 as if it were a reference conversion sequence. If ICS is the
9522 implicit conversion sequence for an implicit object parameter,
9523 modify it accordingly. */
9525 static void
9527 {
9529 {
9530 /* [over.match.funcs]
9532 For non-static member functions, the type of the
9533 implicit object parameter is "reference to cv X"
9534 where X is the class of which the function is a
9535 member and cv is the cv-qualification on the member
9536 function declaration. */
9538 tree reference_type;
9540 /* The `this' parameter is a pointer to a class type. Make the
9541 implicit conversion talk about a reference to that same class
9542 type. */
9555 }
9556 }
9558 /* If *ICS is a REF_BIND set *ICS to the remainder of the conversion,
9559 and return the initial reference binding conversion. Otherwise,
9560 leave *ICS unchanged and return NULL. */
9564 {
9566 {
9571 }
9574 }
9576 /* Compare two implicit conversion sequences according to the rules set out in
9577 [over.ics.rank]. Return values:
9579 1: ics1 is better than ics2
9580 -1: ics2 is better than ics1
9581 0: ics1 and ics2 are indistinguishable */
9583 static int
9585 {
9586 tree from_type1;
9587 tree from_type2;
9588 tree to_type1;
9589 tree to_type2;
9596 /* REF_BINDING is nonzero if the result of the conversion sequence
9597 is a reference type. In that case REF_CONV is the reference
9598 binding conversion. */
9602 /* Compare badness before stripping the reference conversion. */
9608 /* Handle implicit object parameters. */
9612 /* Handle reference parameters. */
9616 /* List-initialization sequence L1 is a better conversion sequence than
9617 list-initialization sequence L2 if L1 converts to
9618 std::initializer_list<X> for some X and L2 does not. */
9624 /* [over.ics.rank]
9626 When comparing the basic forms of implicit conversion sequences (as
9627 defined in _over.best.ics_)
9629 --a standard conversion sequence (_over.ics.scs_) is a better
9630 conversion sequence than a user-defined conversion sequence
9631 or an ellipsis conversion sequence, and
9633 --a user-defined conversion sequence (_over.ics.user_) is a
9634 better conversion sequence than an ellipsis conversion sequence
9635 (_over.ics.ellipsis_). */
9636 /* Use BAD_CONVERSION_RANK because we already checked for a badness
9637 mismatch. If both ICS are bad, we try to make a decision based on
9638 what would have happened if they'd been good. This is not an
9639 extension, we'll still give an error when we build up the call; this
9640 just helps us give a more helpful error message. */
9650 /* Both conversions are ellipsis conversions. */
9653 /* User-defined conversion sequence U1 is a better conversion sequence
9654 than another user-defined conversion sequence U2 if they contain the
9655 same user-defined conversion operator or constructor and if the sec-
9656 ond standard conversion sequence of U1 is better than the second
9657 standard conversion sequence of U2. */
9659 /* Handle list-conversion with the same code even though it isn't always
9660 ranked as a user-defined conversion and it doesn't have a second
9661 standard conversion sequence; it will still have the desired effect.
9662 Specifically, we need to do the reference binding comparison at the
9663 end of this function. */
9666 {
9682 {
9687 }
9688 else
9689 {
9690 /* For ambiguous or aggregate conversions, use the target type as
9691 a proxy for the conversion function. */
9694 }
9696 /* We can just fall through here, after setting up
9697 FROM_TYPE1 and FROM_TYPE2. */
9700 }
9701 else
9702 {
9706 /* We're dealing with two standard conversion sequences.
9708 [over.ics.rank]
9710 Standard conversion sequence S1 is a better conversion
9711 sequence than standard conversion sequence S2 if
9713 --S1 is a proper subsequence of S2 (comparing the conversion
9714 sequences in the canonical form defined by _over.ics.scs_,
9715 excluding any Lvalue Transformation; the identity
9716 conversion sequence is considered to be a subsequence of
9717 any non-identity conversion sequence */
9728 }
9730 /* One sequence can only be a subsequence of the other if they start with
9731 the same type. They can start with different types when comparing the
9732 second standard conversion sequence in two user-defined conversion
9733 sequences. */
9735 {
9740 }
9742 /* [over.ics.rank]
9744 Or, if not that,
9746 --the rank of S1 is better than the rank of S2 (by the rules
9747 defined below):
9749 Standard conversion sequences are ordered by their ranks: an Exact
9750 Match is a better conversion than a Promotion, which is a better
9751 conversion than a Conversion.
9753 Two conversion sequences with the same rank are indistinguishable
9754 unless one of the following rules applies:
9756 --A conversion that does not a convert a pointer, pointer to member,
9757 or std::nullptr_t to bool is better than one that does.
9759 The ICS_STD_RANK automatically handles the pointer-to-bool rule,
9760 so that we do not have to check it explicitly. */
9769 /* A conversion from scalar arithmetic type to complex is worse than a
9770 conversion between scalar arithmetic types. */
9777 {
9780 else
9782 }
9788 {
9793 }
9794 /* The rules for pointers to members A::* are just like the rules
9795 for pointers A*, except opposite: if B is derived from A then
9796 A::* converts to B::*, not vice versa. For that reason, we
9797 switch the from_ and to_ variables here. */
9804 {
9809 }
9814 {
9815 /* This was one of the pointer or pointer-like conversions.
9817 [over.ics.rank]
9819 --If class B is derived directly or indirectly from class A,
9820 conversion of B* to A* is better than conversion of B* to
9821 void*, and conversion of A* to void* is better than
9822 conversion of B* to void*. */
9825 {
9827 deref_from_type2))
9830 deref_from_type1))
9832 }
9835 {
9837 {
9839 {
9841 deref_to_type1))
9843 }
9844 /* We know that DEREF_TO_TYPE1 is `void' here. */
9846 deref_to_type2))
9848 }
9849 }
9852 {
9853 /* [over.ics.rank]
9855 --If class B is derived directly or indirectly from class A
9856 and class C is derived directly or indirectly from B,
9858 --conversion of C* to B* is better than conversion of C* to
9859 A*,
9861 --conversion of B* to A* is better than conversion of C* to
9862 A* */
9864 {
9866 deref_to_type2))
9869 deref_to_type1))
9871 }
9873 {
9875 deref_from_type1))
9878 deref_from_type2))
9880 }
9881 }
9882 }
9885 {
9888 /* [over.ics.rank]
9890 --binding of an expression of type C to a reference of type
9891 B& is better than binding an expression of type C to a
9892 reference of type A&
9894 --conversion of C to B is better than conversion of C to A, */
9897 {
9902 }
9903 }
9906 {
9909 /* [over.ics.rank]
9911 --binding of an expression of type B to a reference of type
9912 A& is better than binding an expression of type C to a
9913 reference of type A&,
9915 --conversion of B to A is better than conversion of C to A */
9918 {
9923 }
9924 }
9926 /* [over.ics.rank]
9928 --S1 and S2 differ only in their qualification conversion and yield
9929 similar types T1 and T2 (_conv.qual_), respectively, and the cv-
9930 qualification signature of type T1 is a proper subset of the cv-
9931 qualification signature of type T2 */
9935 {
9939 }
9941 /* [over.ics.rank]
9943 --S1 and S2 are reference bindings (_dcl.init.ref_) and neither refers
9944 to an implicit object parameter of a non-static member function
9945 declared without a ref-qualifier, and either S1 binds an lvalue
9946 reference to an lvalue and S2 binds an rvalue reference or S1 binds an
9947 rvalue reference to an rvalue and S2 binds an lvalue reference (C++0x
9948 draft standard, 13.3.3.2)
9950 --S1 and S2 are reference bindings (_dcl.init.ref_), and the
9951 types to which the references refer are the same type except for
9952 top-level cv-qualifiers, and the type to which the reference
9953 initialized by S2 refers is more cv-qualified than the type to
9954 which the reference initialized by S1 refers.
9956 DR 1328 [over.match.best]: the context is an initialization by
9957 conversion function for direct reference binding (13.3.1.6) of a
9958 reference to function type, the return type of F1 is the same kind of
9959 reference (i.e. lvalue or rvalue) as the reference being initialized,
9960 and the return type of F2 is not. */
9963 {
9970 {
9974 /* Don't prefer a bad conversion that drops cv-quals to a bad
9975 conversion with the wrong rvalueness. */
9979 }
9982 {
9986 {
9987 /* Prefer the one that drops fewer cv-quals. */
9992 }
9994 }
9995 }
9997 /* Neither conversion sequence is better than the other. */
9999 }
10001 /* The source type for this standard conversion sequence. */
10003 static tree
10005 {
10007 {
10012 }
10014 }
10016 /* Note a warning about preferring WINNER to LOSER. We do this by storing
10017 a pointer to LOSER and re-running joust to produce the warning if WINNER
10018 is actually used. */
10020 static void
10022 {
10028 }
10030 /* Compare two candidates for overloading as described in
10031 [over.match.best]. Return values:
10033 1: cand1 is better than cand2
10034 -1: cand2 is better than cand1
10035 0: cand1 and cand2 are indistinguishable */
10037 static int
10039 tsubst_flags_t complain)
10040 {
10046 /* Candidates that involve bad conversions are always worse than those
10047 that don't. */
10053 /* If we have two pseudo-candidates for conversions to the same type,
10054 or two candidates for the same function, arbitrarily pick one. */
10059 /* Prefer a non-deleted function over an implicitly deleted move
10060 constructor or assignment operator. This differs slightly from the
10061 wording for issue 1402 (which says the move op is ignored by overload
10062 resolution), but this way produces better error messages. */
10066 {
10073 }
10075 /* a viable function F1
10076 is defined to be a better function than another viable function F2 if
10077 for all arguments i, ICSi(F1) is not a worse conversion sequence than
10078 ICSi(F2), and then */
10080 /* for some argument j, ICSj(F1) is a better conversion sequence than
10081 ICSj(F2) */
10083 /* For comparing static and non-static member functions, we ignore
10084 the implicit object parameter of the non-static function. The
10085 standard says to pretend that the static function has an object
10086 parm, but that won't work with operator overloading. */
10089 {
10095 /* We're comparing a near-match list constructor and a near-match
10096 non-list constructor. Just treat them as unordered. */
10103 else
10104 {
10107 }
10108 }
10111 {
10117 {
10119 && warn_sign_promo
10131 {
10138 else
10143 {
10147 }
10148 else
10150 }
10153 {
10156 }
10158 }
10159 }
10161 /* warn about confusing overload resolution for user-defined conversions,
10162 either between a constructor and a conversion op, or between two
10163 conversion ops. */
10168 {
10174 else
10177 /* We don't want to complain about `X::operator T1 ()'
10178 beating `X::operator T2 () const', when T2 is a no less
10179 cv-qualified version of T1. */
10182 {
10187 {
10190 }
10193 }
10194 else
10200 {
10207 {
10209 }
10210 }
10211 else
10213 }
10218 /* DR 495 moved this tiebreaker above the template ones. */
10219 /* or, if not that,
10220 the context is an initialization by user-defined conversion (see
10221 _dcl.init_ and _over.match.user_) and the standard conversion
10222 sequence from the return type of F1 to the destination type (i.e.,
10223 the type of the entity being initialized) is a better conversion
10224 sequence than the standard conversion sequence from the return type
10225 of F2 to the destination type. */
10228 {
10232 }
10234 /* or, if not that,
10235 F1 is a non-template function and F2 is a template function
10236 specialization. */
10243 /* or, if not that,
10244 F1 and F2 are template functions and the function template for F1 is
10245 more specialized than the template for F2 according to the partial
10246 ordering rules. */
10249 {
10250 winner = more_specialized_fn
10253 /* [temp.func.order]: The presence of unused ellipsis and default
10254 arguments has no effect on the partial ordering of function
10255 templates. add_function_candidate() will not have
10256 counted the "this" argument for constructors. */
10260 }
10262 // C++ Concepts
10263 // or, if not that, F1 is more constrained than F2.
10265 {
10269 }
10271 /* F1 is generated from a deduction-guide (13.3.1.8) and F2 is not */
10273 {
10275 /* We distinguish between candidates from an explicit deduction guide and
10276 candidates built from a constructor based on DECL_ARTIFICIAL. */
10283 {
10284 /* Prefer the special copy guide over a declared copy/move
10285 constructor. */
10291 /* Prefer a candidate generated from a non-template constructor. */
10296 }
10297 }
10299 /* F1 is a member of a class D, F2 is a member of a base class B of D, and
10300 for all arguments the corresponding parameters of F1 and F2 have the same
10301 type (CWG 2273/2277). */
10306 {
10320 {
10322 {
10327 }
10330 }
10331 }
10333 /* Check whether we can discard a builtin candidate, either because we
10334 have two identical ones or matching builtin and non-builtin candidates.
10336 (Pedantically in the latter case the builtin which matched the user
10337 function should not be added to the overload set, but we spot it here.
10339 [over.match.oper]
10340 ... the builtin candidates include ...
10341 - do not have the same parameter type list as any non-template
10342 non-member candidate. */
10345 {
10351 {
10353 /* Two built-in candidates; arbitrarily pick one. */
10356 /* cand1 is built-in; prefer cand2. */
10358 else
10359 /* cand2 is built-in; prefer cand1. */
10361 }
10362 }
10364 /* For candidates of a multi-versioned function, make the version with
10365 the highest priority win. This version will be checked for dispatching
10366 first. If this version can be inlined into the caller, the front-end
10367 will simply make a direct call to this function. */
10373 {
10379 /* Check if cand1->fn and cand2->fn are versions of the same function. It
10380 is possible that cand1->fn and cand2->fn are function versions but of
10381 different functions. Check types to see if they are versions of the same
10382 function. */
10385 {
10386 /* Always make the version with the higher priority, more
10387 specialized, win. */
10391 else
10393 }
10394 }
10396 /* If the two function declarations represent the same function (this can
10397 happen with declarations in multiple scopes and arg-dependent lookup),
10398 arbitrarily choose one. But first make sure the default args we're
10399 using match. */
10402 {
10409 {
10410 /* Don't crash if the fn is variadic. */
10415 }
10423 {
10426 {
10428 {
10430 {
10432 "default argument mismatch in "
10434 {
10439 }
10440 }
10441 else
10443 }
10444 else
10447 }
10450 }
10453 }
10455 tweak:
10457 /* Extension: If the worst conversion for one candidate is worse than the
10458 worst conversion for the other, take the first. */
10460 {
10465 {
10470 }
10476 {
10477 /* Don't choose a deleted function over ambiguity. */
10481 {
10483 "ISO C++ says that these are ambiguous, even "
10484 "though the worst conversion for the first is better than "
10488 }
10489 else
10492 }
10493 }
10497 }
10499 /* Given a list of candidates for overloading, find the best one, if any.
10500 This algorithm has a worst case of O(2n) (winner is last), and a best
10501 case of O(n/2) (totally ambiguous); much better than a sorting
10502 algorithm. */
10506 {
10511 /* Walk through the list once, comparing each current champ to the next
10512 candidate, knocking out a candidate or two with each comparison. */
10515 {
10519 else
10520 {
10522 {
10527 }
10528 else
10529 {
10532 }
10535 }
10536 }
10538 /* Make sure the champ is better than all the candidates it hasn't yet
10539 been compared to. */
10542 challenger != champ
10545 {
10549 }
10552 }
10554 /* Returns nonzero if things of type FROM can be converted to TO. */
10556 bool
10558 {
10560 /* implicit_conversion only considers user-defined conversions
10561 if it has an expression for the call argument list. */
10565 }
10567 /* Returns nonzero if things of type FROM can be converted to TO with a
10568 standard conversion. */
10570 bool
10572 {
10574 }
10576 /* Returns nonzero if ARG (of type FROM) can be converted to TO. */
10578 bool
10580 tsubst_flags_t complain)
10581 {
10586 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10588 /* We want to discard any access checks done for this test,
10589 as we might not be in the appropriate access context and
10590 we'll do the check again when we actually perform the
10591 conversion. */
10598 /* Discard the access checks now. */
10600 /* Free all the conversions we allocated. */
10604 }
10606 /* Like can_convert_arg, but allows dubious conversions as well. */
10608 bool
10610 tsubst_flags_t complain)
10611 {
10615 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10617 /* Try to perform the conversion. */
10620 /* Free all the conversions we allocated. */
10624 }
10626 /* Convert EXPR to TYPE. Return the converted expression.
10628 Note that we allow bad conversions here because by the time we get to
10629 this point we are committed to doing the conversion. If we end up
10630 doing a bad conversion, convert_like will complain. */
10632 tree
10635 {
10642 else
10648 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10656 {
10658 {
10659 /* If expr has unknown type, then it is an overloaded function.
10660 Call instantiate_type to get good error messages. */
10665 else
10668 }
10670 }
10672 {
10673 /* In a template, we are only concerned about determining the
10674 type of non-dependent expressions, so we do not have to
10675 perform the actual conversion. But for initializers, we
10676 need to be able to perform it at instantiation
10677 (or instantiate_non_dependent_expr) time. */
10681 }
10682 else
10685 /* Free all the conversions we allocated. */
10689 }
10691 tree
10693 {
10695 LOOKUP_IMPLICIT);
10696 }
10698 /* Convert EXPR to TYPE (as a direct-initialization) if that is
10699 permitted. If the conversion is valid, the converted expression is
10700 returned. Otherwise, NULL_TREE is returned, except in the case
10701 that TYPE is a class type; in that case, an error is issued. If
10702 C_CAST_P is true, then this direct-initialization is taking
10703 place as part of a static_cast being attempted as part of a C-style
10704 cast. */
10706 tree
10708 tree expr,
10710 tsubst_flags_t complain)
10711 {
10717 /* [dcl.init]
10719 If the destination type is a (possibly cv-qualified) class type:
10721 -- If the initialization is direct-initialization ...,
10722 constructors are considered. ... If no constructor applies, or
10723 the overload resolution is ambiguous, the initialization is
10724 ill-formed. */
10726 {
10732 }
10734 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10738 c_cast_p,
10743 {
10744 /* In a template, we are only concerned about determining the
10745 type of non-dependent expressions, so we do not have to
10746 perform the actual conversion. But for initializers, we
10747 need to be able to perform it at instantiation
10748 (or instantiate_non_dependent_expr) time. */
10751 }
10752 else
10755 c_cast_p,
10756 complain);
10758 /* Free all the conversions we allocated. */
10762 }
10764 /* When initializing a reference that lasts longer than a full-expression,
10765 this special rule applies:
10767 [class.temporary]
10769 The temporary to which the reference is bound or the temporary
10770 that is the complete object to which the reference is bound
10771 persists for the lifetime of the reference.
10773 The temporaries created during the evaluation of the expression
10774 initializing the reference, except the temporary to which the
10775 reference is bound, are destroyed at the end of the
10776 full-expression in which they are created.
10778 In that case, we store the converted expression into a new
10779 VAR_DECL in a new scope.
10781 However, we want to be careful not to create temporaries when
10782 they are not required. For example, given:
10784 struct B {};
10785 struct D : public B {};
10786 D f();
10787 const B& b = f();
10789 there is no need to copy the return value from "f"; we can just
10790 extend its lifetime. Similarly, given:
10792 struct S {};
10793 struct T { operator S(); };
10794 T t;
10795 const S& s = t;
10797 we can extend the lifetime of the return value of the conversion
10798 operator.
10800 The next several functions are involved in this lifetime extension. */
10802 /* DECL is a VAR_DECL or FIELD_DECL whose type is a REFERENCE_TYPE. The
10803 reference is being bound to a temporary. Create and return a new
10804 VAR_DECL with the indicated TYPE; this variable will store the value to
10805 which the reference is bound. */
10807 tree
10809 {
10812 /* Register the variable. */
10815 {
10816 /* Namespace-scope or local static; give it a mangled name. */
10817 /* FIXME share comdat with decl? */
10828 }
10829 else
10830 /* Create a new cleanup level if necessary. */
10834 }
10836 /* EXPR is the initializer for a variable DECL of reference or
10837 std::initializer_list type. Create, push and return a new VAR_DECL
10838 for the initializer so that it will live as long as DECL. Any
10839 cleanup for the new variable is returned through CLEANUP, and the
10840 code to initialize the new variable is returned through INITP. */
10842 static tree
10845 {
10846 tree init;
10847 tree type;
10848 tree var;
10850 /* Create the temporary variable. */
10854 /* If the rvalue is the result of a function call it will be
10855 a TARGET_EXPR. If it is some other construct (such as a
10856 member access expression where the underlying object is
10857 itself the result of a function call), turn it into a
10858 TARGET_EXPR here. It is important that EXPR be a
10859 TARGET_EXPR below since otherwise the INIT_EXPR will
10860 attempt to make a bitwise copy of EXPR to initialize
10861 VAR. */
10867 {
10871 }
10873 /* Recursively extend temps in this initializer. */
10877 /* Any reference temp has a non-trivial initializer. */
10880 /* If the initializer is constant, put it in DECL_INITIAL so we get
10881 static initialization and use in constant expressions. */
10883 /* As in store_init_value. */
10886 {
10888 {
10889 /* 5.19 says that a constant expression can include an
10890 lvalue-rvalue conversion applied to "a glvalue of literal type
10891 that refers to a non-volatile temporary object initialized
10892 with a constant expression". Rather than try to communicate
10893 that this VAR_DECL is a temporary, just mark it constexpr.
10895 Currently this is only useful for initializer_list temporaries,
10896 since reference vars can't appear in constant expressions. */
10900 }
10903 }
10904 else
10905 /* Create the INIT_EXPR that will initialize the temporary
10906 variable. */
10909 {
10914 else
10915 {
10919 }
10921 /* We must be careful to destroy the temporary only
10922 after its initialization has taken place. If the
10923 initialization throws an exception, then the
10924 destructor should not be run. We cannot simply
10925 transform INIT into something like:
10927 (INIT, ({ CLEANUP_STMT; }))
10929 because emit_local_var always treats the
10930 initializer as a full-expression. Thus, the
10931 destructor would run too early; it would run at the
10932 end of initializing the reference variable, rather
10933 than at the end of the block enclosing the
10934 reference variable.
10936 The solution is to pass back a cleanup expression
10937 which the caller is responsible for attaching to
10938 the statement tree. */
10939 }
10940 else
10941 {
10944 {
10947 tls_aggregates);
10948 else
10950 static_aggregates);
10951 }
10952 else
10953 /* Check whether the dtor is callable. */
10955 }
10956 /* Avoid -Wunused-variable warning (c++/38958). */
10963 }
10965 /* Convert EXPR to the indicated reference TYPE, in a way suitable for
10966 initializing a variable of that TYPE. */
10968 tree
10971 {
10979 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10985 {
10987 {
10996 else
11000 }
11002 }
11005 /* Perform the conversion. */
11008 /* We gave an error in build_user_type_conversion_1. */
11010 else
11013 /* Free all the conversions we allocated. */
11017 }
11019 /* Subroutine of extend_ref_init_temps. Possibly extend one initializer,
11020 which is bound either to a reference or a std::initializer_list. */
11022 static tree
11024 {
11029 {
11033 }
11036 /* Deal with binding to a subobject. */
11040 {
11048 }
11050 }
11052 /* INIT is part of the initializer for DECL. If there are any
11053 reference or initializer lists being initialized, extend their
11054 lifetime to match that of DECL. */
11056 tree
11058 {
11064 else
11065 {
11070 {
11072 {
11073 /* The temporary array underlying a std::initializer_list
11074 is handled like a reference temporary. */
11078 }
11079 else
11080 {
11086 }
11090 }
11091 }
11094 }
11096 /* Returns true iff an initializer for TYPE could contain temporaries that
11097 need to be extended because they are bound to references or
11098 std::initializer_list. */
11100 bool
11102 {
11107 {
11114 }
11116 }
11118 /* Returns true iff TYPE is some variant of std::initializer_list. */
11120 bool
11122 {
11127 /* Look through typedefs. */
11132 }
11134 /* Returns true iff DECL is a list constructor: i.e. a constructor which
11135 will accept an argument list of a single std::initializer_list<T>. */
11137 bool
11139 {
11141 tree arg;
11153 /* There are more non-defaulted parms. */
11157 }