| blob | 209c1fd2f0e810b56ad7875471fff21977bcb7be |
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 {
322 /* Handle both CALL_EXPRs and AGGR_INIT_EXPRs. */
325 /* We check both the decl and the type; a function may be known not to
326 throw without being declared throw(). */
342 }
344 tree
346 {
347 tree decl;
348 tree result_type;
349 tree fntype;
359 /* An rvalue has no cv-qualifiers. */
370 {
371 /* We invoke build_call directly for several library
372 functions. These may have been declared normally if
373 we're building libgcc, so we can't just check
374 DECL_ARTIFICIAL. */
379 }
385 /* Don't pass empty class objects by value. This is useful
386 for tags in STL, which are used to control overload resolution.
387 We don't need to handle other cases of copying empty classes. */
390 {
394 {
398 }
399 }
402 }
404 /* New overloading code. */
411 };
413 /* Information for providing diagnostics about why overloading failed. */
416 rr_none,
417 rr_arity,
418 rr_explicit_conversion,
419 rr_template_conversion,
420 rr_arg_conversion,
421 rr_bad_arg_conversion,
422 rr_template_unification,
423 rr_invalid_copy,
424 rr_inherited_ctor,
425 rr_constraint_failure
426 };
429 /* The index of the argument, 0-based. */
431 /* The actual argument or its type. */
432 tree from;
433 /* The type of the parameter. */
434 tree to_type;
435 };
440 /* Information about an arity mismatch. */
442 /* The expected number of arguments. */
444 /* The actual number of arguments in the call. */
446 /* Whether the call was a varargs call. */
449 /* Information about an argument conversion mismatch. */
451 /* Same, but for bad argument conversions. */
453 /* Information about template unification failures. These are the
454 parameters passed to fn_type_unification. */
456 tree tmpl;
457 tree explicit_targs;
461 tree return_type;
462 unification_kind_t strict;
465 /* Information about template instantiation failures. These are the
466 parameters passed to instantiate_template. */
468 tree tmpl;
469 tree targs;
472 };
475 /* The FUNCTION_DECL that will be called if this candidate is
476 selected by overload resolution. */
477 tree fn;
478 /* If not NULL_TREE, the first argument to use when calling this
479 function. */
480 tree first_arg;
481 /* The rest of the arguments to use when calling this function. If
482 there are no further arguments this may be NULL or it may be an
483 empty vector. */
485 /* The implicit conversion sequences for each of the arguments to
486 FN. */
488 /* The number of implicit conversion sequences. */
490 /* If FN is a user-defined conversion, the standard conversion
491 sequence from the type returned by FN to the desired destination
492 type. */
495 /* If FN is a member function, the binfo indicating the path used to
496 qualify the name of FN at the call site. This path is used to
497 determine whether or not FN is accessible if it is selected by
498 overload resolution. The DECL_CONTEXT of FN will always be a
499 (possibly improper) base of this binfo. */
500 tree access_path;
501 /* If FN is a non-static member function, the binfo indicating the
502 subobject to which the `this' pointer should be converted if FN
503 is selected by overload resolution. The type pointed to by
504 the `this' pointer must correspond to the most derived class
505 indicated by the CONVERSION_PATH. */
506 tree conversion_path;
507 tree template_decl;
508 tree explicit_targs;
513 /* The flags active in add_candidate. */
515 };
517 /* Returns true iff T is a null pointer constant in the sense of
518 [conv.ptr]. */
520 bool
522 {
525 /* [conv.ptr]
527 A null pointer constant is an integral constant expression
528 (_expr.const_) rvalue of integer type that evaluates to zero or
529 an rvalue of type std::nullptr_t. */
534 {
537 /* Core issue 903 says only literal 0 is a null pointer constant. */
544 }
546 {
551 }
554 }
556 /* Returns true iff T is a null member pointer value (4.11). */
558 bool
560 {
569 else
571 }
573 /* Returns nonzero if PARMLIST consists of only default parms,
574 ellipsis, and/or undeduced parameter packs. */
576 bool
578 {
585 }
587 /* Allocate N bytes of memory from the conversion obstack. The memory
588 is zeroed before being returned. */
592 {
595 {
598 }
602 }
604 /* Allocate rejection reasons. */
608 {
613 }
617 {
623 }
627 {
634 }
638 {
645 }
649 {
655 }
659 {
665 }
672 {
679 /* Copy args to our own storage. */
687 }
691 {
693 }
697 {
700 }
704 {
707 }
709 // Build a constraint failure record, saving information into the
710 // template_instantiation field of the rejection. If FN is not a template
711 // declaration, the TMPL member is the FN declaration and TARGS is empty.
715 {
718 {
721 }
722 else
723 {
726 }
728 }
730 /* Dynamically allocate a conversion. */
734 {
739 }
741 /* Make sure that all memory on the conversion obstack has been
742 freed. */
744 void
746 {
750 }
752 /* Dynamically allocate an array of N conversions. */
756 {
758 }
762 {
766 /* Note that the caller is responsible for filling in t->cand for
767 user-defined conversions. */
773 {
790 }
796 }
798 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
799 specialization of std::initializer_list<T>, if such a conversion is
800 possible. */
804 {
810 tree val;
812 /* Within a list-initialization we can have more user-defined
813 conversions. */
815 /* But no narrowing conversions. */
818 /* Can't make an array of these types. */
825 {
826 conversion *sub
833 }
841 {
849 }
852 }
854 /* Return the next conversion of the conversion chain (if applicable),
855 or NULL otherwise. Please use this function instead of directly
856 accessing fields of struct conversion. */
860 {
867 }
869 /* Subroutine of build_aggr_conv: check whether CTOR, a braced-init-list,
870 is a valid aggregate initializer for array type ATYPE. */
872 static bool
874 {
878 {
884 else
886 complain);
889 }
891 }
893 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
894 aggregate class, if such a conversion is possible. */
898 {
904 /* We already called reshape_init in implicit_conversion. */
906 /* The conversions within the init-list aren't affected by the enclosing
907 context; they're always simple copy-initialization. */
911 {
913 tree val;
921 /* Value-initialization of reference is ill-formed. */
923 else
924 {
928 }
934 else
936 complain);
943 }
955 }
957 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
958 array type, if such a conversion is possible. */
962 {
967 tree val;
972 /* We might need to propagate the size from the element to the array. */
977 {
981 }
986 {
987 conversion *sub
999 }
1008 }
1010 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
1011 complex type, if such a conversion is possible. */
1015 tsubst_flags_t complain)
1016 {
1021 tree val;
1032 {
1033 conversion *sub
1045 }
1054 }
1056 /* Build a representation of the identity conversion from EXPR to
1057 itself. The TYPE should match the type of EXPR, if EXPR is non-NULL. */
1061 {
1069 }
1071 /* Converting from EXPR to TYPE was ambiguous in the sense that there
1072 were multiple user-defined conversions to accomplish the job.
1073 Build a conversion that indicates that ambiguity. */
1077 {
1085 }
1087 tree
1089 {
1093 }
1095 /* Returns the standard conversion path (see [conv]) from type FROM to type
1096 TO, if any. For proper handling of null pointer constants, you must
1097 also pass the expression EXPR to convert from. If C_CAST_P is true,
1098 this conversion is coming from a C-style cast. */
1103 {
1107 tree qualified_to;
1111 {
1114 }
1120 {
1122 {
1128 }
1130 {
1131 /* Necessary for eg, TEMPLATE_ID_EXPRs (c++/50961). */
1134 }
1135 }
1142 {
1145 /* Tell convert_like_real that we're using the address. */
1148 }
1149 /* Wrapping a ck_rvalue around a class prvalue (as a result of using
1150 obvalue_p) seems odd, since it's already a prvalue, but that's how we
1151 express the copy constructor call required by copy-initialization. */
1153 {
1155 {
1156 tree bitfield_type;
1159 {
1162 }
1163 }
1166 /* Tell convert_like_real to set LOOKUP_PREFER_RVALUE. */
1168 }
1170 /* Allow conversion between `__complex__' data types. */
1172 {
1173 /* The standard conversion sequence to convert FROM to TO is
1174 the standard conversion sequence to perform componentwise
1175 conversion. */
1178 complain);
1181 {
1184 }
1185 else
1189 }
1192 {
1196 }
1198 /* [conv.ptr]
1199 A null pointer constant can be converted to a pointer type; ... A
1200 null pointer constant of integral type can be converted to an
1201 rvalue of type std::nullptr_t. */
1209 {
1210 /* For backwards brain damage compatibility, allow interconversion of
1211 pointers and integers with a pedwarn. */
1214 }
1216 {
1217 /* For backwards brain damage compatibility, allow interconversion of
1218 enums and integers with a pedwarn. */
1221 }
1224 {
1225 tree to_pointee;
1226 tree from_pointee;
1229 {
1233 /* Since this is the target of a pointer, it can't have function
1234 qualifiers, so any TYPE_QUALS must be for attributes const or
1235 noreturn. Strip them. */
1242 }
1243 else
1244 {
1247 }
1251 to_pointee))
1252 ;
1256 {
1258 /* Don't try to apply restrict to void. */
1263 }
1265 {
1272 && (same_type_ignoring_top_level_qualifiers_p
1274 {
1277 }
1278 else
1280 }
1283 /* [conv.ptr]
1285 An rvalue of type "pointer to cv D," where D is a
1286 class type, can be converted to an rvalue of type
1287 "pointer to cv B," where B is a base class (clause
1288 _class.derived_) of D. If B is an inaccessible
1289 (clause _class.access_) or ambiguous
1290 (_class.member.lookup_) base class of D, a program
1291 that necessitates this conversion is ill-formed.
1292 Therefore, we use DERIVED_FROM_P, and do not check
1293 access or uniqueness. */
1295 {
1296 from_pointee
1302 }
1307 /* In a C-style cast, we ignore CV-qualification because we
1308 are allowed to perform a static_cast followed by a
1309 const_cast. */
1314 /* converting from string constant to char *. */
1318 /* Allow conversions among compatible ObjC pointer types (base
1319 conversions have been already handled above). */
1324 {
1327 }
1328 else
1332 }
1334 {
1348 else
1352 {
1354 tbase,
1360 }
1363 }
1365 {
1366 /* [conv.bool]
1368 A prvalue of arithmetic, unscoped enumeration, pointer, or pointer
1369 to member type can be converted to a prvalue of type bool. ...
1370 For direct-initialization (8.5 [dcl.init]), a prvalue of type
1371 std::nullptr_t can be converted to a prvalue of type bool; */
1377 {
1388 }
1391 }
1392 /* We don't check for ENUMERAL_TYPE here because there are no standard
1393 conversions to enum type. */
1394 /* As an extension, allow conversion to complex type. */
1396 {
1403 /* Give this a better rank if it's a promotion. */
1407 }
1413 {
1417 /* The derived-to-base conversion indicates the initialization
1418 of a parameter with base type from an object of a derived
1419 type. A temporary object is created to hold the result of
1420 the conversion unless we're binding directly to a reference. */
1422 }
1423 else
1430 }
1432 /* Returns nonzero if T1 is reference-related to T2. */
1434 bool
1436 {
1443 /* [dcl.init.ref]
1445 Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
1446 to "cv2 T2" if T1 is the same type as T2, or T1 is a base class
1447 of T2. */
1451 }
1453 /* Returns nonzero if T1 is reference-compatible with T2. */
1455 static bool
1457 {
1458 /* [dcl.init.ref]
1460 "cv1 T1" is reference compatible with "cv2 T2" if
1461 * T1 is reference-related to T2 or
1462 * T2 is "noexcept function" and T1 is "function", where the
1463 function types are otherwise the same,
1464 and cv1 is the same cv-qualification as, or greater cv-qualification
1465 than, cv2. */
1469 }
1471 /* A reference of the indicated TYPE is being bound directly to the
1472 expression represented by the implicit conversion sequence CONV.
1473 Return a conversion sequence for this binding. */
1477 {
1478 tree t;
1486 /* Mark the identity conv as to not decay to rvalue. */
1489 /* [over.ics.rank]
1491 When a parameter of reference type binds directly
1492 (_dcl.init.ref_) to an argument expression, the implicit
1493 conversion sequence is the identity conversion, unless the
1494 argument expression has a type that is a derived class of the
1495 parameter type, in which case the implicit conversion sequence is
1496 a derived-to-base Conversion.
1498 If the parameter binds directly to the result of applying a
1499 conversion function to the argument expression, the implicit
1500 conversion sequence is a user-defined conversion sequence
1501 (_over.ics.user_), with the second standard conversion sequence
1502 either an identity conversion or, if the conversion function
1503 returns an entity of a type that is a derived class of the
1504 parameter type, a derived-to-base conversion. */
1506 {
1507 /* Represent the derived-to-base conversion. */
1509 /* We will actually be binding to the base-class subobject in
1510 the derived class, so we mark this conversion appropriately.
1511 That way, convert_like knows not to generate a temporary. */
1513 }
1516 }
1518 /* Returns the conversion path from type FROM to reference type TO for
1519 purposes of reference binding. For lvalue binding, either pass a
1520 reference type to FROM or an lvalue expression to EXPR. If the
1521 reference will be bound to a temporary, NEED_TEMPORARY_P is set for
1522 the conversion returned. If C_CAST_P is true, this
1523 conversion is coming from a C-style cast. */
1527 tsubst_flags_t complain)
1528 {
1532 tree tfrom;
1535 cp_lvalue_kind gl_kind;
1539 {
1544 }
1547 {
1549 /* DR 1288: Otherwise, if the initializer list has a single element
1550 of type E and ... [T's] referenced type is reference-related to E,
1551 the object or reference is initialized from that element... */
1553 {
1559 {
1563 }
1564 }
1565 /* Otherwise, if T is a reference type, a prvalue temporary of the type
1566 referenced by T is copy-list-initialized, and the reference is bound
1567 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 /* Like implicit_conversion, but return NULL if the conversion is bad.
1934 This is not static so that check_non_deducible_conversion can call it within
1935 add_template_candidate_real as part of overload resolution; it should not be
1936 called outside of overload resolution. */
1938 conversion *
1941 {
1947 }
1949 /* Add a new entry to the list of candidates. Used by the add_*_candidate
1950 functions. ARGS will not be changed until a single candidate is
1951 selected. */
1960 {
1978 }
1980 /* Return the number of remaining arguments in the parameter list
1981 beginning with ARG. */
1983 int
1985 {
1990 n++;
1993 }
1995 /* [over.match.copy]: When initializing a temporary object (12.2) to be bound
1996 to the first parameter of a constructor where the parameter is of type
1997 "reference to possibly cv-qualified T" and the constructor is called with a
1998 single argument in the context of direct-initialization of an object of type
1999 "cv2 T", explicit conversion functions are also considered.
2001 So set LOOKUP_COPY_PARM to let reference_binding know that
2002 it's being called in that context. */
2004 int
2006 {
2008 tree t;
2011 && (same_type_ignoring_top_level_qualifiers_p
2013 {
2019 }
2020 else
2024 }
2026 /* Create an overload candidate for the function or method FN called
2027 with the argument list FIRST_ARG/ARGS and add it to CANDIDATES.
2028 FLAGS is passed on to implicit_conversion.
2030 This does not change ARGS.
2032 CTYPE, if non-NULL, is the type we want to pretend this function
2033 comes from for purposes of overload resolution. */
2041 tsubst_flags_t complain)
2042 {
2045 tree parmnode;
2051 /* At this point we should not see any functions which haven't been
2052 explicitly declared, except for friend functions which will have
2053 been found using argument dependent lookup. */
2056 /* The `this', `in_chrg' and VTT arguments to constructors are not
2057 considered in overload resolution. */
2059 {
2061 /* Bring back parameters omitted from an inherited ctor. */
2063 else
2067 {
2070 }
2071 }
2072 else
2079 /* 13.3.2 - Viable functions [over.match.viable]
2080 First, to be a viable function, a candidate function shall have enough
2081 parameters to agree in number with the arguments in the list.
2083 We need to check this first; otherwise, checking the ICSes might cause
2084 us to produce an ill-formed template instantiation. */
2088 {
2092 }
2096 {
2100 }
2102 /* An inherited constructor (12.6.3 [class.inhctor.init]) that has a first
2103 parameter of type "reference to cv C" (including such a constructor
2104 instantiated from a template) is excluded from the set of candidate
2105 functions when used to construct an object of type D with an argument list
2106 containing a single argument if C is reference-related to D. */
2108 && flag_new_inheriting_ctors
2110 {
2116 {
2119 }
2120 }
2122 /* Second, for a function to be viable, its constraints must be
2123 satisfied. */
2126 {
2129 }
2131 /* When looking for a function from a subobject from an implicit
2132 copy/move constructor/operator=, don't consider anything that takes (a
2133 reference to) an unrelated type. See c++/44909 and core 1092. */
2135 {
2141 else
2144 {
2147 ctype))
2149 }
2151 /* This only applies at the top level. */
2153 }
2158 /* Third, for F to be a viable function, there shall exist for each
2159 argument an implicit conversion sequence that converts that argument
2160 to the corresponding parameter of F. */
2165 {
2167 tree arg;
2175 {
2176 /* Already set during deduction. */
2179 }
2183 else
2192 {
2197 /* The type of the implicit object parameter ('this') for
2198 overload resolution is not always the same as for the
2199 function itself; conversion functions are considered to
2200 be members of the class being converted, and functions
2201 introduced by a using-declaration are considered to be
2202 members of the class that uses them.
2204 Since build_over_call ignores the ICS for the `this'
2205 parameter, we can just change the parm type. */
2207 {
2208 parmtype = cp_build_qualified_type
2211 {
2212 /* If the function has a ref-qualifier, the implicit
2213 object parameter has reference type. */
2216 /* The special handling of 'this' conversions in compare_ics
2217 does not apply if there is a ref-qualifier. */
2219 }
2220 else
2221 {
2223 /* We don't use build_this here because we don't want to
2224 capture the object argument until we've chosen a
2225 non-static member function. */
2228 }
2229 }
2236 }
2237 else
2238 {
2242 }
2249 {
2253 }
2256 {
2259 }
2260 }
2262 out:
2265 }
2267 /* Create an overload candidate for the conversion function FN which will
2268 be invoked for expression OBJ, producing a pointer-to-function which
2269 will in turn be called with the argument list FIRST_ARG/ARGLIST,
2270 and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
2271 passed on to implicit_conversion.
2273 Actually, we don't really care about FN; we care about the type it
2274 converts to. There may be multiple conversion functions that will
2275 convert to that type, and we rely on build_user_type_conversion_1 to
2276 choose the best one; so when we create our candidate, we record the type
2277 instead of the function. */
2283 tsubst_flags_t complain)
2284 {
2302 /* Don't bother looking up the same type twice. */
2307 {
2313 else
2318 {
2321 /* Leave the 'cand' field null; we'll figure out the conversion in
2322 convert_like_real if this candidate is chosen. */
2324 }
2328 {
2332 }
2333 else
2334 {
2338 }
2345 {
2348 }
2355 }
2359 {
2363 }
2367 }
2369 static void
2373 {
2387 /* TRUTH_*_EXPR do "contextual conversion to bool", which means explicit
2388 conversion ops are allowed. We handle that here by just checking for
2389 boolean_type_node because other operators don't ask for it. COND_EXPR
2390 also does contextual conversion to bool for the first operand, but we
2391 handle that in build_conditional_expr, and type1 here is operand 2. */
2396 {
2403 {
2405 /* We need something for printing the candidate. */
2409 }
2411 {
2415 }
2417 }
2419 /* For COND_EXPR we rearranged the arguments; undo that now. */
2421 {
2426 complain);
2429 else
2430 {
2433 boolean_type_node);
2434 }
2435 }
2442 }
2444 static bool
2446 {
2448 }
2450 /* Returns nonzero if TYPE is a promoted arithmetic type. */
2452 static bool
2454 {
2455 /* [over.built]
2457 In this section, the term promoted integral type is used to refer
2458 to those integral types which are preserved by integral promotion
2459 (including e.g. int and long but excluding e.g. char).
2460 Similarly, the term promoted arithmetic type refers to promoted
2461 integral types plus floating types. */
2465 }
2467 /* Create any builtin operator overload candidates for the operator in
2468 question given the converted operand types TYPE1 and TYPE2. The other
2469 args are passed through from add_builtin_candidates to
2470 build_builtin_candidate.
2472 TYPE1 and TYPE2 may not be permissible, and we must filter them.
2473 If CODE is requires candidates operands of the same type of the kind
2474 of which TYPE1 and TYPE2 are, we add both candidates
2475 CODE (TYPE1, TYPE1) and CODE (TYPE2, TYPE2). */
2477 static void
2481 tsubst_flags_t complain)
2482 {
2484 {
2492 }
2495 {
2497 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2498 and VQ is either volatile or empty, there exist candidate operator
2499 functions of the form
2500 VQ T& operator++(VQ T&);
2501 T operator++(VQ T&, int);
2502 5 For every pair T, VQ), where T is an enumeration type or an arithmetic
2503 type other than bool, and VQ is either volatile or empty, there exist
2504 candidate operator functions of the form
2505 VQ T& operator--(VQ T&);
2506 T operator--(VQ T&, int);
2507 6 For every pair T, VQ), where T is a cv-qualified or cv-unqualified
2508 complete object type, and VQ is either volatile or empty, there exist
2509 candidate operator functions of the form
2510 T*VQ& operator++(T*VQ&);
2511 T*VQ& operator--(T*VQ&);
2512 T* operator++(T*VQ&, int);
2513 T* operator--(T*VQ&, int); */
2519 /* FALLTHRU */
2523 {
2526 }
2529 /* 7 For every cv-qualified or cv-unqualified object type T, there
2530 exist candidate operator functions of the form
2532 T& operator*(T*);
2534 8 For every function type T, there exist candidate operator functions of
2535 the form
2536 T& operator*(T*); */
2545 /* 9 For every type T, there exist candidate operator functions of the form
2546 T* operator+(T*);
2548 10For every promoted arithmetic type T, there exist candidate operator
2549 functions of the form
2550 T operator+(T);
2551 T operator-(T); */
2556 /* FALLTHRU */
2562 /* 11For every promoted integral type T, there exist candidate operator
2563 functions of the form
2564 T operator~(T); */
2571 /* 12For every quintuple C1, C2, T, CV1, CV2), where C2 is a class type, C1
2572 is the same type as C2 or is a derived class of C2, T is a complete
2573 object type or a function type, and CV1 and CV2 are cv-qualifier-seqs,
2574 there exist candidate operator functions of the form
2575 CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
2576 where CV12 is the union of CV1 and CV2. */
2580 {
2588 }
2591 /* 13For every pair of promoted arithmetic types L and R, there exist can-
2592 didate operator functions of the form
2593 LR operator*(L, R);
2594 LR operator/(L, R);
2595 LR operator+(L, R);
2596 LR operator-(L, R);
2597 bool operator<(L, R);
2598 bool operator>(L, R);
2599 bool operator<=(L, R);
2600 bool operator>=(L, R);
2601 bool operator==(L, R);
2602 bool operator!=(L, R);
2603 where LR is the result of the usual arithmetic conversions between
2604 types L and R.
2606 14For every pair of types T and I, where T is a cv-qualified or cv-
2607 unqualified complete object type and I is a promoted integral type,
2608 there exist candidate operator functions of the form
2609 T* operator+(T*, I);
2610 T& operator[](T*, I);
2611 T* operator-(T*, I);
2612 T* operator+(I, T*);
2613 T& operator[](I, T*);
2615 15For every T, where T is a pointer to complete object type, there exist
2616 candidate operator functions of the form112)
2617 ptrdiff_t operator-(T, T);
2619 16For every pointer or enumeration type T, there exist candidate operator
2620 functions of the form
2621 bool operator<(T, T);
2622 bool operator>(T, T);
2623 bool operator<=(T, T);
2624 bool operator>=(T, T);
2625 bool operator==(T, T);
2626 bool operator!=(T, T);
2628 17For every pointer to member type T, there exist candidate operator
2629 functions of the form
2630 bool operator==(T, T);
2631 bool operator!=(T, T); */
2638 {
2641 }
2642 /* FALLTHRU */
2655 {
2658 }
2660 {
2663 }
2664 /* Fall through. */
2680 {
2683 }
2686 {
2689 }
2695 /* FALLTHRU */
2698 {
2701 }
2703 {
2706 }
2709 /* 18For every pair of promoted integral types L and R, there exist candi-
2710 date operator functions of the form
2711 LR operator%(L, R);
2712 LR operator&(L, R);
2713 LR operator^(L, R);
2714 LR operator|(L, R);
2715 L operator<<(L, R);
2716 L operator>>(L, R);
2717 where LR is the result of the usual arithmetic conversions between
2718 types L and R. */
2726 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2730 /* 19For every triple L, VQ, R), where L is an arithmetic or enumeration
2731 type, VQ is either volatile or empty, and R is a promoted arithmetic
2732 type, there exist candidate operator functions of the form
2733 VQ L& operator=(VQ L&, R);
2734 VQ L& operator*=(VQ L&, R);
2735 VQ L& operator/=(VQ L&, R);
2736 VQ L& operator+=(VQ L&, R);
2737 VQ L& operator-=(VQ L&, R);
2739 20For every pair T, VQ), where T is any type and VQ is either volatile
2740 or empty, there exist candidate operator functions of the form
2741 T*VQ& operator=(T*VQ&, T*);
2743 21For every pair T, VQ), where T is a pointer to member type and VQ is
2744 either volatile or empty, there exist candidate operator functions of
2745 the form
2746 VQ T& operator=(VQ T&, T);
2748 22For every triple T, VQ, I), where T is a cv-qualified or cv-
2749 unqualified complete object type, VQ is either volatile or empty, and
2750 I is a promoted integral type, there exist candidate operator func-
2751 tions of the form
2752 T*VQ& operator+=(T*VQ&, I);
2753 T*VQ& operator-=(T*VQ&, I);
2755 23For every triple L, VQ, R), where L is an integral or enumeration
2756 type, VQ is either volatile or empty, and R is a promoted integral
2757 type, there exist candidate operator functions of the form
2759 VQ L& operator%=(VQ L&, R);
2760 VQ L& operator<<=(VQ L&, R);
2761 VQ L& operator>>=(VQ L&, R);
2762 VQ L& operator&=(VQ L&, R);
2763 VQ L& operator^=(VQ L&, R);
2764 VQ L& operator|=(VQ L&, R); */
2768 {
2772 {
2775 }
2776 /* FALLTHRU */
2789 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2802 {
2805 }
2810 }
2815 /* [over.built]
2817 For every pair of promoted arithmetic types L and R, there
2818 exist candidate operator functions of the form
2820 LR operator?(bool, L, R);
2822 where LR is the result of the usual arithmetic conversions
2823 between types L and R.
2825 For every type T, where T is a pointer or pointer-to-member
2826 type, there exist candidate operator functions of the form T
2827 operator?(bool, T, T); */
2831 /* That's OK. */
2834 /* Otherwise, the types should be pointers. */
2838 /* We don't check that the two types are the same; the logic
2839 below will actually create two candidates; one in which both
2840 parameter types are TYPE1, and one in which both parameter
2841 types are TYPE2. */
2852 }
2854 /* Make sure we don't create builtin candidates with dependent types. */
2858 {
2859 /* Try to recover if one of the types is non-dependent. But if
2860 there's only one type, there's nothing we can do. */
2863 /* And we lose if both are dependent. */
2866 /* Or if they have different forms. */
2874 }
2876 /* If we're dealing with two pointer types or two enumeral types,
2877 we need candidates for both of them. */
2886 {
2888 {
2890 error_mark_node,
2891 error_mark_node,
2892 CPO_CONVERSION,
2893 tf_none);
2895 {
2896 build_builtin_candidate
2900 }
2901 }
2903 build_builtin_candidate
2905 build_builtin_candidate
2908 }
2910 build_builtin_candidate
2912 }
2914 tree
2916 {
2922 }
2924 /* There are three conditions of builtin candidates:
2926 1) bool-taking candidates. These are the same regardless of the input.
2927 2) pointer-pair taking candidates. These are generated for each type
2928 one of the input types converts to.
2929 3) arithmetic candidates. According to the standard, we should generate
2930 all of these, but I'm trying not to...
2932 Here we generate a superset of the possible candidates for this particular
2933 case. That is a subset of the full set the standard defines, plus some
2934 other cases which the standard disallows. add_builtin_candidate will
2935 filter out the invalid set. */
2937 static void
2941 {
2945 /* TYPES[i] is the set of possible builtin-operator parameter types
2946 we will consider for the Ith argument. */
2951 {
2954 else
2956 }
2959 {
2960 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2961 and VQ is either volatile or empty, there exist candidate operator
2962 functions of the form
2963 VQ T& operator++(VQ T&); */
2973 /* 24There also exist candidate operator functions of the form
2974 bool operator!(bool);
2975 bool operator&&(bool, bool);
2976 bool operator||(bool, bool); */
2979 build_builtin_candidate
2986 build_builtin_candidate
3004 /* Fall through. */
3008 }
3014 {
3016 ;
3018 {
3019 tree convs;
3027 {
3032 }
3038 {
3051 {
3057 }
3061 }
3062 }
3063 else
3064 {
3069 {
3075 }
3077 }
3078 }
3080 /* Run through the possible parameter types of both arguments,
3081 creating candidates with those parameter types. */
3083 {
3085 tree u;
3089 add_builtin_candidate
3092 else
3093 add_builtin_candidate
3096 }
3100 }
3103 /* If TMPL can be successfully instantiated as indicated by
3104 EXPLICIT_TARGS and ARGLIST, adds the instantiation to CANDIDATES.
3106 TMPL is the template. EXPLICIT_TARGS are any explicit template
3107 arguments. ARGLIST is the arguments provided at the call-site.
3108 This does not change ARGLIST. The RETURN_TYPE is the desired type
3109 for conversion operators. If OBJ is NULL_TREE, FLAGS and CTYPE are
3110 as for add_function_candidate. If an OBJ is supplied, FLAGS and
3111 CTYPE are ignored, and OBJ is as for add_conv_candidate. */
3119 tsubst_flags_t complain)
3120 {
3130 tree arg;
3132 tree fn;
3137 /* We don't do deduction on the in-charge parameter, the VTT
3138 parameter or 'this'. */
3140 {
3144 /* We're deducing for a call to the result of a template conversion
3146 else
3148 }
3153 {
3156 else
3158 }
3166 {
3167 /* 12.8/6 says, "A declaration of a constructor for a class X is
3168 ill-formed if its first parameter is of type (optionally cv-qualified)
3169 X and either there are no other parameters or else all other
3170 parameters have default arguments. A member function template is never
3171 instantiated to produce such a constructor signature."
3173 So if we're trying to copy an object of the containing class, don't
3174 consider a template constructor that has a first parameter type that
3175 is just a template parameter, as we would deduce a signature that we
3176 would then reject in the code below. */
3178 {
3183 {
3187 }
3188 }
3189 }
3196 {
3199 }
3203 {
3206 }
3213 args_without_in_chrg,
3214 nargs_without_in_chrg,
3219 {
3220 /* Don't repeat unification later if it already resulted in errors. */
3224 nargs_without_in_chrg,
3226 else
3229 }
3232 {
3235 ctype))
3236 {
3237 /* We're trying to produce a constructor with a prohibited signature,
3238 as discussed above; handle here any cases we didn't catch then,
3239 such as X(X<T>). */
3242 }
3243 }
3246 /* Aha, this is a conversion function. */
3249 else
3254 /* This situation can occur if a member template of a template
3255 class is specialized. Then, instantiate_template might return
3256 an instantiation of the specialization, in which case the
3257 DECL_TI_TEMPLATE field will point at the original
3258 specialization. For example:
3260 template <class T> struct S { template <class U> void f(U);
3261 template <> void f(int) {}; };
3262 S<double> sd;
3263 sd.f(3);
3265 Here, TMPL will be template <class U> S<double>::f(U).
3266 And, instantiate template will give us the specialization
3267 template <> S<double>::f(int). But, the DECL_TI_TEMPLATE field
3268 for this will point at template <class T> template <> S<T>::f(int),
3269 so that we can find the definition. For the purposes of
3270 overload resolution, however, we want the original TMPL. */
3272 else
3277 fail:
3280 }
3289 {
3290 return
3295 }
3297 /* Create an overload candidate for the conversion function template TMPL,
3298 returning RETURN_TYPE, which will be invoked for expression OBJ to produce a
3299 pointer-to-function which will in turn be called with the argument list
3300 ARGLIST, and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
3301 passed on to implicit_conversion. */
3305 tree obj,
3309 {
3310 /* Making this work broke PR 71117 and 85118, so until the committee resolves
3311 core issue 2189, let's disable this candidate if there are any call
3312 operators. */
3316 return
3320 complain);
3321 }
3323 /* The CANDS are the set of candidates that were considered for
3324 overload resolution. Return the set of viable candidates, or CANDS
3325 if none are viable. If any of the candidates were viable, set
3326 *ANY_VIABLE_P to true. STRICT_P is true if a candidate should be
3327 considered viable only if it is strictly viable. */
3333 {
3339 /* Be strict inside templates, since build_over_call won't actually
3340 do the conversions to get pedwarns. */
3350 {
3354 {
3355 /* Be strict in the presence of a viable candidate. Also if
3356 there are template candidates, so that we get deduction errors
3357 for them instead of silently preferring a bad conversion. */
3360 {
3361 /* Put any spliced near matches back onto the main list so
3362 that we see them if there is no strict match. */
3368 }
3369 }
3372 {
3380 }
3381 else
3383 }
3386 }
3388 static bool
3390 {
3395 }
3397 /* OBJ is being used in an expression like "OBJ.f (...)". In other
3398 words, it is about to become the "this" pointer for a member
3399 function call. Take the address of the object. */
3401 static tree
3403 {
3404 /* In a template, we are only concerned about the type of the
3405 expression, so we can take a shortcut. */
3410 }
3412 /* Returns true iff functions are equivalent. Equivalent functions are
3413 not '==' only if one is a function-local extern function or if
3414 both are extern "C". */
3418 {
3427 }
3429 /* Print information about a candidate being rejected due to INFO. */
3431 static void
3433 {
3438 {
3439 /* Conversion of implicit `this' argument failed. */
3441 /* A bad conversion for 'this' must be discarding cv-quals. */
3444 from);
3445 else
3449 }
3451 {
3456 tf_warning_or_error);
3457 }
3459 /* Conversion of conversion function return value failed. */
3462 else
3465 }
3467 /* Print information about a candidate with WANT parameters and we found
3468 HAVE. */
3470 static void
3472 {
3477 }
3479 /* Print information about one overload candidate CANDIDATE. MSGSTR
3480 is the text to print before the candidate itself.
3482 NOTE: Unlike most diagnostic functions in GCC, MSGSTR is expected
3483 to have been run through gettext by the caller. This wart makes
3484 life simpler in print_z_candidates and for the translators. */
3486 static void
3489 {
3499 {
3510 else
3513 }
3520 else
3523 {
3526 }
3527 /* Give the user some information about why this candidate failed. */
3529 {
3533 {
3546 "cannot be converted to %qT with a qualification "
3552 "conversion function specialization to %qT is not an "
3557 /* We use template_unification_error_rejection if unification caused
3558 actual non-SFINAE errors, in which case we don't need to repeat
3559 them here. */
3561 {
3565 }
3566 /* Re-run template unification with diagnostics. */
3570 (make_tree_vec
3581 " a constructor taking a single argument of its own "
3585 {
3589 }
3593 "initialization from an expression of the same or derived "
3598 /* This candidate didn't have any issues or we failed to
3599 handle a particular code. Either way... */
3601 }
3602 }
3603 }
3605 static void
3607 {
3614 /* Remove non-viable deleted candidates. */
3617 {
3622 else
3624 }
3625 /* ...if there are any non-deleted ones. */
3629 /* There may be duplicates in the set of candidates. We put off
3630 checking this condition as long as possible, since we have no way
3631 to eliminate duplicates from a set of functions in less than n^2
3632 time. Now we are about to emit an error message, so it is more
3633 permissible to go slowly. */
3635 {
3637 /* Skip builtin candidates and conversion functions. */
3642 {
3646 else
3648 }
3649 }
3653 }
3655 /* USER_SEQ is a user-defined conversion sequence, beginning with a
3656 USER_CONV. STD_SEQ is the standard conversion sequence applied to
3657 the result of the conversion function to convert it to the final
3658 desired type. Merge the two sequences into a single sequence,
3659 and return the merged sequence. */
3663 {
3669 /* Find the end of the second conversion sequence. */
3671 {
3672 /* The entire sequence is a user-conversion sequence. */
3676 }
3679 /* We're binding a reference directly to the result of the conversion.
3680 build_user_type_conversion_1 stripped the REFERENCE_TYPE from the return
3681 type, but we want it back. */
3684 /* Replace the identity conversion with the user conversion
3685 sequence. */
3689 }
3691 /* Handle overload resolution for initializing an object of class type from
3692 an initializer list. First we look for a suitable constructor that
3693 takes a std::initializer_list; if we don't find one, we then look for a
3694 non-list constructor.
3696 Parameters are as for add_candidates, except that the arguments are in
3697 the form of a CONSTRUCTOR (the initializer list) rather than a vector, and
3698 the RETURN_TYPE parameter is replaced by TOTYPE, the desired type. */
3700 static void
3707 tsubst_flags_t complain)
3708 {
3711 /* We're looking for a ctor for list-initialization. */
3713 /* And we don't allow narrowing conversions. We also use this flag to
3714 avoid the copy constructor call for copy-list-initialization. */
3720 /* Always use the default constructor if the list is empty (DR 990). */
3723 ;
3724 /* If the class has a list ctor, try passing the list as a single
3725 argument first, but only consider list ctors. */
3727 {
3734 }
3736 /* Expand the CONSTRUCTOR into a new argument vec. */
3744 /* We aren't looking for list-ctors anymore. */
3746 /* We allow more user-defined conversions within an init-list. */
3752 }
3754 /* Returns the best overload candidate to perform the requested
3755 conversion. This function is used for three the overloading situations
3756 described in [over.match.copy], [over.match.conv], and [over.match.ref].
3757 If TOTYPE is a REFERENCE_TYPE, we're trying to find a direct binding as
3758 per [dcl.init.ref], so we ignore temporary bindings. */
3762 tsubst_flags_t complain)
3763 {
3765 tree fromtype;
3779 /* We represent conversion within a hierarchy using RVALUE_CONV and
3780 BASE_CONV, as specified by [over.best.ics]; these become plain
3781 constructor calls, as specified in [dcl.init]. */
3786 /* Use lookup_fnfields_slot instead of lookup_fnfields to avoid
3787 creating a garbage BASELINK; constructors can't be inherited. */
3791 {
3796 {
3797 /* [class.conv.fct] A conversion function is never used to
3798 convert a (possibly cv-qualified) object to the (possibly
3799 cv-qualified) same object type (or a reference to it), to a
3800 (possibly cv-qualified) base class of that type (or a
3801 reference to it)... */
3802 }
3803 else
3805 }
3812 /* It's OK to bind a temporary for converting constructor arguments, but
3813 not in converting the return value of a conversion operator. */
3819 {
3824 /* We should never try to call the abstract or base constructor
3825 from here. */
3831 {
3832 /* List-initialization. */
3836 }
3837 else
3838 {
3842 }
3845 {
3848 /* If totype isn't a reference, and LOOKUP_NO_TEMP_BIND isn't
3849 set, then this is copy-initialization. In that case, "The
3850 result of the call is then used to direct-initialize the
3851 object that is the destination of the copy-initialization."
3852 [dcl.init]
3854 We represent this in the conversion sequence with an
3855 rvalue conversion, which means a constructor call. */
3858 cand->second_conv
3860 }
3861 }
3864 {
3867 else
3869 }
3872 {
3876 /* If we are called to convert to a reference type, we are trying to
3877 find a direct binding, so don't even consider temporaries. If
3878 we don't find a direct binding, the caller will try again to
3879 look for a temporary binding. */
3890 {
3892 conversion *ics
3894 rettype,
3897 complain);
3899 /* If LOOKUP_NO_TEMP_BIND isn't set, then this is
3900 copy-initialization. In that case, "The result of the
3901 call is then used to direct-initialize the object that is
3902 the destination of the copy-initialization." [dcl.init]
3904 We represent this in the conversion sequence with an
3905 rvalue conversion, which means a constructor call. But
3906 don't add a second rvalue conversion if there's already
3907 one there. Which there really shouldn't be, but it's
3908 harmless since we'd add it here anyway. */
3916 {
3920 }
3923 {
3924 /* 13.3.1.5: For direct-initialization, those explicit
3925 conversion functions that are not hidden within S and
3926 yield type T or a type that can be converted to type T
3927 with a qualification conversion (4.4) are also candidate
3928 functions. */
3929 /* 13.3.1.6 doesn't have a parallel restriction, but it should;
3930 I've raised this issue with the committee. --jason 9/2011 */
3933 }
3935 {
3937 cand->reason
3940 }
3943 {
3944 /* 13.3.3.1.2: If the user-defined conversion is specified by
3945 a specialization of a conversion function template, the
3946 second standard conversion sequence shall have exact match
3947 rank. */
3950 }
3951 }
3952 }
3956 {
3960 }
3964 {
3966 {
3970 }
3979 /* If there are viable candidates, don't set ICS_BAD_FLAG; an
3980 ambiguous conversion is no worse than another user-defined
3981 conversion. */
3984 }
3986 tree convtype;
3990 /* DR 5: [in the first step of copy-initialization]...if the function
3991 is a constructor, the call initializes a temporary of the
3992 cv-unqualified version of the destination type. */
3994 else
3996 /* Build the user conversion sequence. */
3997 conv = build_conv
3999 convtype,
4005 /* Remember that this was a list-initialization. */
4009 /* Combine it with the second conversion sequence. */
4014 }
4016 /* Wrapper for above. */
4018 tree
4020 tsubst_flags_t complain)
4021 {
4023 tree ret;
4029 {
4032 else
4033 {
4036 }
4037 }
4038 else
4043 }
4045 /* Subroutine of convert_nontype_argument.
4047 EXPR is an expression used in a context that requires a converted
4048 constant-expression, such as a template non-type parameter. Do any
4049 necessary conversions (that are permitted for converted
4050 constant-expressions) to convert it to the desired type.
4052 If conversion is successful, returns the converted expression;
4053 otherwise, returns error_mark_node. */
4055 tree
4057 {
4060 tree t;
4066 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4073 /* A converted constant expression of type T is an expression, implicitly
4074 converted to type T, where the converted expression is a constant
4075 expression and the implicit conversion sequence contains only
4077 * user-defined conversions,
4078 * lvalue-to-rvalue conversions (7.1),
4079 * array-to-pointer conversions (7.2),
4080 * function-to-pointer conversions (7.3),
4081 * qualification conversions (7.5),
4082 * integral promotions (7.6),
4083 * integral conversions (7.8) other than narrowing conversions (11.6.4),
4084 * null pointer conversions (7.11) from std::nullptr_t,
4085 * null member pointer conversions (7.12) from std::nullptr_t, and
4086 * function pointer conversions (7.13),
4088 and where the reference binding (if any) binds directly. */
4093 {
4095 {
4096 /* A conversion function is OK. If it isn't constexpr, we'll
4097 complain later that the argument isn't constant. */
4099 /* The lvalue-to-rvalue conversion is OK. */
4101 /* Array-to-pointer and function-to-pointer. */
4103 /* Function pointer conversions. */
4105 /* Qualification conversions. */
4111 {
4117 }
4127 /* Integral promotion or conversion. */
4130 /* Conversion from nullptr to pointer or pointer-to-member. */
4136 /* fall through. */
4141 }
4142 }
4144 /* Avoid confusing convert_nontype_argument by introducing
4145 a redundant conversion to the same reference type. */
4148 {
4152 }
4156 else
4159 /* Free all the conversions we allocated. */
4163 }
4165 /* Do any initial processing on the arguments to a function call. */
4169 {
4171 tree arg;
4174 {
4178 {
4182 }
4185 }
4187 }
4189 /* Perform overload resolution on FN, which is called with the ARGS.
4191 Return the candidate function selected by overload resolution, or
4192 NULL if the event that overload resolution failed. In the case
4193 that overload resolution fails, *CANDIDATES will be the set of
4194 candidates considered, and ANY_VIABLE_P will be set to true or
4195 false to indicate whether or not any of the candidates were
4196 viable.
4198 The ARGS should already have gone through RESOLVE_ARGS before this
4199 function is called. */
4206 {
4208 tree explicit_targs;
4219 /* Check FN. */
4226 {
4230 }
4232 /* Add the various candidate functions. */
4237 LOOKUP_NORMAL,
4243 else
4248 }
4250 /* Print an error message about being unable to build a call to FN with
4251 ARGS. ANY_VIABLE_P indicates whether any candidate functions could
4252 be located; CANDIDATES is a possibly empty list of such
4253 functions. */
4255 static void
4258 {
4261 {
4264 }
4273 else
4278 }
4280 /* Return an expression for a call to FN (a namespace-scope function,
4281 or a static member function) with the ARGS. This may change
4282 ARGS. */
4284 tree
4286 tsubst_flags_t complain)
4287 {
4291 tree result;
4294 {
4298 }
4303 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4307 complain);
4310 {
4312 {
4313 // If there is a single (non-viable) function candidate,
4314 // let the error be diagnosed by cp_build_function_call_vec.
4319 // Otherwise, emit notes for non-viable candidates.
4321 }
4323 }
4324 else
4325 {
4327 /* If fn is template_id_expr, the call has explicit template arguments
4328 (e.g. func<int>(5)), communicate this info to build_over_call
4329 through flags so that later we can use it to decide whether to warn
4330 about peculiar null pointer conversion. */
4332 {
4333 /* If overload resolution selects a specialization of a
4334 function concept for non-dependent template arguments,
4335 the expression is true if the constraints are satisfied
4336 and false otherwise.
4338 NOTE: This is an extension of Concepts Lite TS that
4339 allows constraints to be used in expressions. */
4341 {
4347 }
4350 }
4353 }
4355 /* Free all the conversions we allocated. */
4359 }
4361 /* Build a call to a global operator new. FNNAME is the name of the
4362 operator (either "operator new" or "operator new[]") and ARGS are
4363 the arguments provided. This may change ARGS. *SIZE points to the
4364 total number of bytes required by the allocation, and is updated if
4365 that is changed here. *COOKIE_SIZE is non-NULL if a cookie should
4366 be used. If this function determines that no cookie should be
4367 used, after all, *COOKIE_SIZE is set to NULL_TREE. If SIZE_CHECK
4368 is not NULL_TREE, it is evaluated before calculating the final
4369 array size, and if it fails, the array size is replaced with
4370 (size_t)-1 (usually triggering a std::bad_alloc exception). If FN
4371 is non-NULL, it will be set, upon return, to the allocation
4372 function called. */
4374 tree
4379 {
4381 tree fns;
4388 /* Set to (size_t)-1 if the size check fails. */
4390 {
4396 }
4402 /* Based on:
4404 [expr.new]
4406 If this lookup fails to find the name, or if the allocated type
4407 is not a class type, the allocation function's name is looked
4408 up in the global scope.
4410 we disregard block-scope declarations of "operator new". */
4415 {
4422 /* If no aligned allocation function matches, try again without the
4423 alignment. */
4424 }
4426 /* Figure out what function is being called. */
4429 complain);
4431 /* If no suitable function could be found, issue an error message
4432 and give up. */
4434 {
4438 }
4440 /* If a cookie is required, add some extra space. Whether
4441 or not a cookie is required cannot be determined until
4442 after we know which function was called. */
4444 {
4446 tree arg_types;
4449 /* Skip the size_t parameter. */
4451 /* Check the remaining parameters (if any). */
4455 ptr_type_node))
4457 /* If we need a cookie, adjust the number of bytes allocated. */
4459 {
4460 /* Update the total size. */
4463 {
4464 /* Set to (size_t)-1 if the size check fails. */
4468 }
4469 /* Update the argument list to reflect the adjusted size. */
4471 }
4472 else
4474 }
4476 /* Tell our caller which function we decided to call. */
4480 /* Build the CALL_EXPR. */
4482 }
4484 /* Build a new call to operator(). This may change ARGS. */
4486 static tree
4488 {
4505 {
4507 /* It's no good looking for an overloaded operator() on a
4508 pointer-to-member-function. */
4512 }
4515 {
4519 }
4520 else
4524 {
4528 }
4530 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4534 {
4542 }
4547 {
4555 {
4562 add_template_conv_candidate
4566 else
4570 }
4571 }
4573 /* Be strict here because if we choose a bad conversion candidate, the
4574 errors we get won't mention the call context. */
4577 {
4579 {
4583 }
4585 }
4586 else
4587 {
4590 {
4592 {
4596 }
4598 }
4603 else
4604 {
4608 else
4609 {
4612 }
4615 }
4616 }
4618 /* Free all the conversions we allocated. */
4622 }
4624 /* Wrapper for above. */
4626 tree
4628 {
4629 tree ret;
4634 }
4636 /* Called by op_error to prepare format strings suitable for the error
4637 function. It concatenates a prefix (controlled by MATCH), ERRMSG,
4638 and a suffix (controlled by NTYPES). */
4642 {
4652 else
4656 }
4658 static void
4661 {
4666 {
4672 else
4684 else
4694 else
4705 else
4715 else
4720 else
4724 else
4729 }
4730 }
4732 /* Return the implicit conversion sequence that could be used to
4733 convert E1 to E2 in [expr.cond]. */
4737 {
4743 /* [expr.cond]
4745 If E2 is an lvalue: E1 can be converted to match E2 if E1 can be
4746 implicitly converted (clause _conv_) to the type "lvalue reference to
4747 T2", subject to the constraint that in the conversion the
4748 reference must bind directly (_dcl.init.ref_) to an lvalue.
4750 If E2 is an xvalue: E1 can be converted to match E2 if E1 can be
4751 implicitly converted to the type "rvalue reference to T2", subject to
4752 the constraint that the reference must bind directly. */
4754 {
4757 t1,
4758 e1,
4760 LOOKUP_NO_TEMP_BIND|LOOKUP_NO_RVAL_BIND
4762 complain);
4765 }
4767 /* If E2 is a prvalue or if neither of the conversions above can be done
4768 and at least one of the operands has (possibly cv-qualified) class
4769 type: */
4773 /* [expr.cond]
4775 If E1 and E2 have class type, and the underlying class types are
4776 the same or one is a base class of the other: E1 can be converted
4777 to match E2 if the class of T2 is the same type as, or a base
4778 class of, the class of T1, and the cv-qualification of T2 is the
4779 same cv-qualification as, or a greater cv-qualification than, the
4780 cv-qualification of T1. If the conversion is applied, E1 is
4781 changed to an rvalue of type T2 that still refers to the original
4782 source class object (or the appropriate subobject thereof). */
4785 {
4787 {
4792 else
4795 }
4796 else
4798 }
4799 else
4800 /* [expr.cond]
4802 Otherwise: E1 can be converted to match E2 if E1 can be implicitly
4803 converted to the type that expression E2 would have if E2 were
4804 converted to an rvalue (or the type it has, if E2 is an rvalue). */
4807 }
4809 /* Implement [expr.cond]. ARG1, ARG2, and ARG3 are the three
4810 arguments to the conditional expression. */
4812 static tree
4814 tsubst_flags_t complain)
4815 {
4816 tree arg2_type;
4817 tree arg3_type;
4826 /* As a G++ extension, the second argument to the conditional can be
4827 omitted. (So that `a ? : c' is roughly equivalent to `a ? a :
4828 c'.) If the second operand is omitted, make sure it is
4829 calculated only once. */
4831 {
4839 /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */
4842 else
4844 }
4846 /* If something has already gone wrong, just pass that fact up the
4847 tree. */
4857 {
4860 /* If arg1 is another cond_expr choosing between -1 and 0,
4861 then we can use its comparison. It may help to avoid
4862 additional comparison, produce more accurate diagnostics
4863 and enables folding. */
4873 /* force_rvalue can return error_mark on valid arguments. */
4884 {
4885 /* Rely on the error messages of the scalar version. */
4894 {
4902 }
4906 /* We could pass complain & tf_warning to unsafe_conversion_p,
4907 but the warnings (like Wsign-conversion) have already been
4908 given by the scalar build_conditional_expr_1. We still check
4909 unsafe_conversion_p to forbid truncating long long -> float. */
4911 {
4916 }
4918 {
4923 }
4933 }
4936 {
4942 {
4946 {
4952 }
4954 {
4960 }
4963 }
4964 }
4970 {
4973 "incompatible vector types in conditional expression: "
4977 }
4980 {
4983 }
4985 }
4987 /* [expr.cond]
4989 The first expression is implicitly converted to bool (clause
4990 _conv_). */
4992 LOOKUP_NORMAL);
4996 /* [expr.cond]
4998 If either the second or the third operand has type (possibly
4999 cv-qualified) void, then the lvalue-to-rvalue (_conv.lval_),
5000 array-to-pointer (_conv.array_), and function-to-pointer
5001 (_conv.func_) standard conversions are performed on the second
5002 and third operands. */
5006 {
5007 /* [expr.cond]
5009 One of the following shall hold:
5011 --The second or the third operand (but not both) is a
5012 throw-expression (_except.throw_); the result is of the type
5013 and value category of the other.
5015 --Both the second and the third operands have type void; the
5016 result is of type void and is a prvalue. */
5019 {
5022 }
5025 {
5028 }
5030 {
5033 }
5034 else
5035 {
5037 {
5040 "second operand to the conditional operator "
5041 "is of type %<void%>, but the third operand is "
5043 else
5045 "third operand to the conditional operator "
5046 "is of type %<void%>, but the second operand is "
5048 }
5050 }
5053 }
5054 /* [expr.cond]
5056 Otherwise, if the second and third operand have different types,
5057 and either has (possibly cv-qualified) class type, or if both are
5058 glvalues of the same value category and the same type except for
5059 cv-qualification, an attempt is made to convert each of those operands
5060 to the type of the other. */
5064 arg3_type)
5067 {
5072 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5078 /* [expr.cond]
5080 If both can be converted, or one can be converted but the
5081 conversion is ambiguous, the program is ill-formed. If
5082 neither can be converted, the operands are left unchanged and
5083 further checking is performed as described below. If exactly
5084 one conversion is possible, that conversion is applied to the
5085 chosen operand and the converted operand is used in place of
5086 the original operand for the remainder of this section. */
5091 {
5093 {
5100 else
5102 }
5104 }
5106 {
5110 /* Even if CONV2 is a valid conversion, the result of the
5111 conversion may be invalid. For example, if ARG3 has type
5112 "volatile X", and X does not have a copy constructor
5113 accepting a "volatile X&", then even if ARG2 can be
5114 converted to X, the conversion will fail. */
5118 }
5120 {
5127 }
5129 /* Free all the conversions we allocated. */
5135 /* If, after the conversion, both operands have class type,
5136 treat the cv-qualification of both operands as if it were the
5137 union of the cv-qualification of the operands.
5139 The standard is not clear about what to do in this
5140 circumstance. For example, if the first operand has type
5141 "const X" and the second operand has a user-defined
5142 conversion to "volatile X", what is the type of the second
5143 operand after this step? Making it be "const X" (matching
5144 the first operand) seems wrong, as that discards the
5145 qualification without actually performing a copy. Leaving it
5146 as "volatile X" seems wrong as that will result in the
5147 conditional expression failing altogether, even though,
5148 according to this step, the one operand could be converted to
5149 the type of the other. */
5157 }
5159 /* [expr.cond]
5161 If the second and third operands are glvalues of the same value
5162 category and have the same type, the result is of that type and
5163 value category. */
5167 {
5172 }
5174 /* [expr.cond]
5176 Otherwise, the result is an rvalue. If the second and third
5177 operand do not have the same type, and either has (possibly
5178 cv-qualified) class type, overload resolution is used to
5179 determine the conversions (if any) to be applied to the operands
5180 (_over.match.oper_, _over.built_). */
5184 {
5189 /* Rearrange the arguments so that add_builtin_candidate only has
5190 to know about two args. In build_builtin_candidate, the
5191 arguments are unscrambled. */
5196 COND_EXPR,
5197 NOP_EXPR,
5199 args,
5202 /* [expr.cond]
5204 If the overload resolution fails, the program is
5205 ill-formed. */
5208 {
5213 }
5216 {
5218 {
5221 }
5223 }
5225 /* [expr.cond]
5227 Otherwise, the conversions thus determined are applied, and
5228 the converted operands are used in place of the original
5229 operands for the remainder of this section. */
5238 }
5240 /* [expr.cond]
5242 Lvalue-to-rvalue (_conv.lval_), array-to-pointer (_conv.array_),
5243 and function-to-pointer (_conv.func_) standard conversions are
5244 performed on the second and third operands.
5246 We need to force the lvalue-to-rvalue conversion here for class types,
5247 so we get TARGET_EXPRs; trying to deal with a COND_EXPR of class rvalues
5248 that isn't wrapped with a TARGET_EXPR plays havoc with exception
5249 regions. */
5262 /* [expr.cond]
5264 After those conversions, one of the following shall hold:
5266 --The second and third operands have the same type; the result is of
5267 that type. */
5270 /* [expr.cond]
5272 --The second and third operands have arithmetic or enumeration
5273 type; the usual arithmetic conversions are performed to bring
5274 them to a common type, and the result is of that type. */
5279 {
5280 /* In this case, there is always a common type. */
5282 arg3_type);
5285 "implicit conversion from %qH to %qI to "
5287 loc);
5291 {
5295 /* Two enumerators from the same enumeration can have different
5301 }
5308 {
5312 }
5316 }
5317 /* [expr.cond]
5319 --The second and third operands have pointer type, or one has
5320 pointer type and the other is a null pointer constant; pointer
5321 conversions (_conv.ptr_) and qualification conversions
5322 (_conv.qual_) are performed to bring them to their composite
5323 pointer type (_expr.rel_). The result is of the composite
5324 pointer type.
5326 --The second and third operands have pointer to member type, or
5327 one has pointer to member type and the other is a null pointer
5328 constant; pointer to member conversions (_conv.mem_) and
5329 qualification conversions (_conv.qual_) are performed to bring
5330 them to a common type, whose cv-qualification shall match the
5331 cv-qualification of either the second or the third operand.
5332 The result is of the common type. */
5340 {
5343 complain);
5348 }
5351 {
5356 }
5361 valid_operands:
5363 {
5364 /* Let lvalue_kind know this was a glvalue. */
5367 }
5371 /* If the ARG2 and ARG3 are the same and don't have side-effects,
5372 warn here, because the COND_EXPR will be turned into ARG2. */
5379 /* We can't use result_type below, as fold might have returned a
5380 throw_expr. */
5383 {
5384 /* Expand both sides into the same slot, hopefully the target of
5385 the ?: expression. We used to check for TARGET_EXPRs here,
5386 but now we sometimes wrap them in NOP_EXPRs so the test would
5387 fail. */
5390 /* If this expression is an rvalue, but might be mistaken for an
5391 lvalue, we must add a NON_LVALUE_EXPR. */
5393 }
5394 else
5398 }
5400 /* Wrapper for above. */
5402 tree
5404 tsubst_flags_t complain)
5405 {
5406 tree ret;
5411 }
5413 /* OPERAND is an operand to an expression. Perform necessary steps
5414 required before using it. If OPERAND is NULL_TREE, NULL_TREE is
5415 returned. */
5417 static tree
5419 {
5421 {
5424 /* Make sure the template type is instantiated now. */
5426 }
5429 }
5431 /* Add each of the viable functions in FNS (a FUNCTION_DECL or
5432 OVERLOAD) to the CANDIDATES, returning an updated list of
5433 CANDIDATES. The ARGS are the arguments provided to the call;
5434 if FIRST_ARG is non-null it is the implicit object argument,
5435 otherwise the first element of ARGS is used if needed. The
5436 EXPLICIT_TARGS are explicit template arguments provided.
5437 TEMPLATE_ONLY is true if only template functions should be
5438 considered. CONVERSION_PATH, ACCESS_PATH, and FLAGS are as for
5439 add_function_candidate. */
5441 static void
5443 tree return_type,
5448 tsubst_flags_t complain)
5449 {
5450 tree ctype;
5454 unification_kind_t strict;
5459 /* Precalculate special handling of constructors and conversion ops. */
5462 {
5466 /* We're doing return_type(x). */
5468 else
5469 /* We're doing x.operator return_type(). */
5471 /* [over.match.funcs] For conversion functions, the function
5472 is considered to be a member of the class of the implicit
5473 object argument for the purpose of defining the type of
5474 the implicit object parameter. */
5476 }
5477 else
5478 {
5480 {
5482 /* For list-initialization we consider explicit constructors
5483 and complain if one is chosen. */
5484 check_converting
5487 }
5490 }
5494 else
5495 /* Delay creating the implicit this parameter until it is needed. */
5499 {
5511 {
5512 /* Figure out where the object arg comes from. If this
5513 function is a non-static member and we didn't get an
5514 implicit object argument, move it out of args. */
5516 {
5518 tree arg;
5525 }
5529 }
5533 fn,
5534 ctype,
5535 explicit_targs,
5536 fn_first_arg,
5537 fn_args,
5538 return_type,
5539 access_path,
5540 conversion_path,
5541 flags,
5542 strict,
5543 complain);
5546 fn,
5547 ctype,
5548 fn_first_arg,
5549 fn_args,
5550 access_path,
5551 conversion_path,
5552 flags,
5553 NULL,
5554 complain);
5555 }
5556 }
5558 /* Returns 1 if P0145R2 says that the LHS of operator CODE is evaluated first,
5559 -1 if the RHS is evaluated first, or 0 if the order is unspecified. */
5561 static int
5563 {
5565 {
5566 // 5. b @= a
5570 // 6. a[b]
5574 // 1. a.b
5575 // Not overloadable (yet).
5576 // 2. a->b
5577 // Only one argument.
5578 // 3. a->*b
5580 // 7. a << b
5582 // 8. a >> b
5588 }
5589 }
5591 static tree
5594 {
5615 {
5618 }
5625 {
5630 /* Use build_op_new_call and build_op_delete_call instead. */
5634 /* Use build_op_call instead. */
5641 /* These are saved for the sake of warn_logical_operator. */
5651 /* These are saved for the sake of maybe_warn_bool_compare. */
5656 /* =, ->, [], () must be non-static member functions. */
5660 /* FALLTHRU */
5668 }
5674 /* Use build_conditional_expr instead. */
5690 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5693 /* Add namespace-scope operators to the list of functions to
5694 consider. */
5696 {
5702 }
5708 /* Add class-member operators to the candidate set. */
5710 {
5711 tree fns;
5715 {
5718 }
5726 }
5727 /* Per 13.3.1.2/3, 2nd bullet, if no operand has a class type, then
5728 only non-member functions that have type T1 or reference to
5729 cv-qualified-opt T1 for the first argument, if the first argument
5730 has an enumeration type, or T2 or reference to cv-qualified-opt
5731 T2 for the second argument, if the second argument has an
5732 enumeration type. Filter out those that don't match. */
5734 {
5738 {
5748 {
5754 && (same_type_ignoring_top_level_qualifiers_p
5759 }
5761 /* No argument has an appropriate type, so remove this
5762 candidate function from the list. */
5764 {
5767 }
5768 }
5769 }
5775 {
5778 /* For these, the built-in candidates set is empty
5779 [over.match.oper]/3. We don't want non-strict matches
5780 because exact matches are always possible with built-in
5781 operators. The built-in candidate set for COMPONENT_REF
5782 would be empty too, but since there are no such built-in
5783 operators, we accept non-strict matches for them. */
5790 }
5794 {
5796 {
5799 /* Don't try anything fancy if we're not allowed to produce
5800 errors. */
5804 /* Look for an `operator++ (int)'. Pre-1985 C++ didn't
5805 distinguish between prefix and postfix ++ and
5806 operator++() was used for both, so we allow this with
5807 -fpermissive. */
5808 else
5809 {
5815 }
5822 else
5828 /* The caller will deal with these. */
5838 {
5839 /* If one of the arguments of the operator represents
5840 an invalid use of member function pointer, try to report
5841 a meaningful error ... */
5846 else
5847 {
5848 /* ... Otherwise, report the more generic
5849 "no matching operator found" error */
5852 }
5853 }
5856 }
5857 }
5858 else
5859 {
5862 {
5864 {
5867 }
5869 }
5871 {
5877 else
5883 {
5888 /* This prevents build_new_function_call from discarding this
5889 function during instantiation of the enclosing template. */
5892 /* Specify evaluation order as per P0145R2. */
5895 {
5906 }
5907 }
5908 }
5909 else
5910 {
5911 /* Give any warnings we noticed during overload resolution. */
5913 {
5917 }
5919 /* Check for comparison of different enum types. */
5921 {
5933 {
5937 }
5941 }
5943 /* We need to strip any leading REF_BIND so that bitfields
5944 don't cause errors. This should not remove any important
5945 conversions, because builtins don't apply to class
5946 objects directly. */
5953 {
5957 else
5960 /* We need to call warn_logical_operator before
5961 converting arg2 to a boolean_type, but after
5962 decaying an enumerator to its value. */
5969 }
5971 {
5976 }
5978 }
5979 }
5981 user_defined_result_ready:
5983 /* Free all the conversions we allocated. */
5989 builtin:
5991 {
6006 /* Fall through. */
6019 /* Fall through. */
6052 complain),
6055 /* The caller will deal with these. */
6063 }
6065 }
6067 /* Wrapper for above. */
6069 tree
6073 {
6074 tree ret;
6080 }
6082 /* CALL was returned by some call-building function; extract the actual
6083 CALL_EXPR from any bits that have been tacked on, e.g. by
6084 convert_from_reference. */
6086 tree
6088 {
6099 }
6101 /* Returns true if FN has two parameters, of which the second has type
6102 size_t. */
6104 static bool
6106 {
6118 }
6120 /* True if T, an allocation function, has std::align_val_t as its second
6121 argument. */
6123 bool
6125 {
6131 }
6133 /* Returns true iff T, an element of an OVERLOAD chain, is a usual deallocation
6134 function (3.7.4.2 [basic.stc.dynamic.deallocation]) with a parameter of
6135 std::align_val_t. */
6137 static bool
6139 {
6143 /* A template instance is never a usual deallocation function,
6144 regardless of its signature. */
6160 }
6162 /* Returns true iff T, an element of an OVERLOAD chain, is a usual
6163 deallocation function (3.7.4.2 [basic.stc.dynamic.deallocation]). */
6165 bool
6167 {
6168 /* A template instance is never a usual deallocation function,
6169 regardless of its signature. */
6174 /* If a class T has a member deallocation function named operator delete
6175 with exactly one parameter, then that function is a usual
6176 (non-placement) deallocation function. If class T does not declare
6177 such an operator delete but does declare a member deallocation
6178 function named operator delete with exactly two parameters, the second
6179 of which has type std::size_t (18.2), then this function is a usual
6180 deallocation function. */
6192 }
6194 /* Build a call to operator delete. This has to be handled very specially,
6195 because the restrictions on what signatures match are different from all
6196 other call instances. For a normal delete, only a delete taking (void *)
6197 or (void *, size_t) is accepted. For a placement delete, only an exact
6198 match with the placement new is accepted.
6200 CODE is either DELETE_EXPR or VEC_DELETE_EXPR.
6201 ADDR is the pointer to be deleted.
6202 SIZE is the size of the memory block to be deleted.
6203 GLOBAL_P is true if the delete-expression should not consider
6204 class-specific delete operators.
6205 PLACEMENT is the corresponding placement new call, or NULL_TREE.
6207 If this call to "operator delete" is being generated as part to
6208 deallocate memory allocated via a new-expression (as per [expr.new]
6209 which requires that if the initialization throws an exception then
6210 we call a deallocation function), then ALLOC_FN is the allocation
6211 function. */
6213 tree
6217 {
6231 /* In [class.free]
6233 If the result of the lookup is ambiguous or inaccessible, or if
6234 the lookup selects a placement deallocation function, the
6235 program is ill-formed.
6237 Therefore, we ask lookup_fnfields to complain about ambiguity. */
6238 {
6242 }
6243 else
6249 /* Strip const and volatile from addr. */
6253 {
6254 /* "A declaration of a placement deallocation function matches the
6255 declaration of a placement allocation function if it has the same
6256 number of parameters and, after parameter transformations (8.3.5),
6257 all parameter types except the first are identical."
6259 So we build up the function type we want and ask instantiate_type
6260 to get it for us. */
6271 /* "If the lookup finds the two-parameter form of a usual deallocation
6272 function (3.7.4.2) and that function, considered as a placement
6273 deallocation function, would have been selected as a match for the
6274 allocation function, the program is ill-formed." */
6276 {
6284 /* But if the class has an operator delete (void *), then that is
6285 the usual deallocation function, so we shouldn't complain
6286 about using the operator delete (void *, size_t). */
6290 {
6295 }
6296 /* Before C++14 a two-parameter global deallocation function is
6297 always a placement deallocation function, but warn if
6298 -Wc++14-compat. */
6300 {
6305 }
6308 {
6310 {
6311 /* Only mention C++14 for namespace-scope delete. */
6314 else
6316 "%qD is a usual (non-placement) deallocation "
6318 }
6319 }
6320 else
6322 ok:;
6323 }
6324 }
6325 else
6326 /* "Any non-placement deallocation function matches a non-placement
6327 allocation function. If the lookup finds a single matching
6328 deallocation function, that function will be called; otherwise, no
6329 deallocation function will be called." */
6331 {
6334 {
6336 {
6339 }
6341 /* -- If the type has new-extended alignment, a function with a
6342 parameter of type std::align_val_t is preferred; otherwise a
6343 function without such a parameter is preferred. If exactly one
6344 preferred function is found, that function is selected and the
6345 selection process terminates. If more than one preferred
6346 function is found, all non-preferred functions are eliminated
6347 from further consideration. */
6349 {
6355 {
6359 }
6360 }
6362 /* -- If the deallocation functions have class scope, the one
6363 without a parameter of type std::size_t is selected. */
6368 /* -- If the type is complete and if, for the second alternative
6369 (delete array) only, the operand is a pointer to a class type
6370 with a non-trivial destructor or a (possibly multi-dimensional)
6371 array thereof, the function with a parameter of type std::size_t
6372 is selected.
6374 -- Otherwise, it is unspecified whether a deallocation function
6375 with a parameter of type std::size_t is selected. */
6376 else
6377 {
6381 /* We need a cookie to determine the array size. */
6383 }
6389 }
6390 }
6392 /* If we have a matching function, call it. */
6394 {
6397 /* If the FN is a member function, make sure that it is
6398 accessible. */
6401 complain);
6403 /* Core issue 901: It's ok to new a type with deleted delete. */
6408 {
6409 /* The placement args might not be suitable for overload
6410 resolution at this point, so build the call directly. */
6420 }
6421 else
6422 {
6423 tree ret;
6429 {
6432 }
6436 }
6437 }
6439 /* [expr.new]
6441 If no unambiguous matching deallocation function can be found,
6442 propagating the exception does not cause the object's memory to
6443 be freed. */
6445 {
6449 alloc_fn);
6451 }
6457 }
6459 /* If the current scope isn't allowed to access DECL along
6460 BASETYPE_PATH, give an error. The most derived class in
6461 BASETYPE_PATH is the one used to qualify DECL. DIAG_DECL is
6462 the declaration to use in the error diagnostic. */
6464 bool
6467 {
6472 {
6473 /* 7.3.3/18: The additional constructors are accessible if they would be
6474 accessible when used to construct an object of the corresponding base
6475 class. */
6479 }
6482 {
6484 {
6488 {
6494 }
6496 {
6502 }
6503 else
6504 {
6509 }
6510 }
6512 }
6515 }
6517 /* Initialize a temporary of type TYPE with EXPR. The FLAGS are a
6518 bitwise or of LOOKUP_* values. If any errors are warnings are
6519 generated, set *DIAGNOSTIC_FN to "error" or "warning",
6520 respectively. If no diagnostics are generated, set *DIAGNOSTIC_FN
6521 to NULL. */
6523 static tree
6526 {
6532 /* If the source is a packed field, calling the copy constructor will require
6533 binding the field to the reference parameter to the copy constructor, and
6534 we'll end up with an infinite loop. If we can use a bitwise copy, then
6535 do that now. */
6551 }
6553 /* Perform warnings about peculiar, but valid, conversions from/to NULL.
6554 Also handle a subset of zero as null warnings.
6555 EXPR is implicitly converted to type TOTYPE.
6556 FN and ARGNUM are used for diagnostics. */
6558 static void
6560 {
6561 /* Issue warnings about peculiar, but valid, uses of NULL. */
6564 {
6565 source_location loc =
6572 else
6575 }
6577 /* Issue warnings if "false" is converted to a NULL pointer */
6580 {
6583 "converting %<false%> to pointer type for argument %P "
6585 else
6588 }
6589 /* Handle zero as null pointer warnings for cases other
6590 than EQ_EXPR and NE_EXPR */
6593 {
6594 source_location loc =
6597 }
6598 }
6600 /* We gave a diagnostic during a conversion. If this was in the second
6601 standard conversion sequence of a user-defined conversion sequence, say
6602 which user-defined conversion. */
6604 static void
6606 {
6610 {
6614 }
6615 }
6617 /* Locate the parameter with the given index within FNDECL.
6618 ARGNUM is zero based, -1 indicates the `this' argument of a method.
6619 Return the location of the FNDECL itself if there are problems. */
6621 location_t
6623 {
6625 tree param;
6627 /* Locate param by index within DECL_ARGUMENTS (fndecl). */
6631 ;
6633 /* If something went wrong (e.g. if we have a builtin and thus no arguments),
6634 return the location of FNDECL. */
6639 }
6641 /* Perform the conversions in CONVS on the expression EXPR. FN and
6642 ARGNUM are used for diagnostics. ARGNUM is zero based, -1
6643 indicates the `this' argument of a method. INNER is nonzero when
6644 being called to continue a conversion chain. It is negative when a
6645 reference binding will be applied, positive otherwise. If
6646 ISSUE_CONVERSION_WARNINGS is true, warnings about suspicious
6647 conversions will be emitted if appropriate. If C_CAST_P is true,
6648 this conversion is coming from a C-style cast; in that case,
6649 conversions to inaccessible bases are permitted. */
6651 static tree
6655 {
6657 diagnostic_t diag_kind;
6673 {
6677 /* Give a helpful error if this is bad because of excess braces. */
6682 {
6688 }
6690 /* Give a helpful error if this is bad because a conversion to bool
6691 from std::nullptr_t requires direct-initialization. */
6699 {
6701 {
6704 totype);
6710 complain);
6714 complain);
6715 else
6721 }
6723 {
6727 complain);
6729 }
6734 complain);
6737 }
6746 }
6752 {
6754 {
6758 /* We chose the surrogate function from add_conv_candidate, now we
6759 actually need to build the conversion. */
6765 /* When converting from an init list we consider explicit
6766 constructors, but actually trying to call one is an error. */
6769 /* Unless this is for direct-list-initialization. */
6771 /* And in C++98 a default constructor can't be explicit. */
6773 {
6779 {
6785 }
6786 else
6789 }
6791 /* If we're initializing from {}, it's value-initialization. */
6795 {
6802 {
6805 }
6807 }
6811 /* Pass LOOKUP_NO_CONVERSION so rvalue/base handling knows not to allow
6812 any more UDCs. */
6814 complain);
6816 /* If this is a constructor or a function returning an aggr type,
6817 we need to build up a TARGET_EXPR. */
6819 {
6822 /* Remember that this was list-initialization. */
6825 }
6828 }
6831 {
6837 else
6839 }
6848 /* If __null has been converted to an integer type, we do not want to
6849 continue to warn about uses of EXPR as an integer, rather than as a
6850 pointer. */
6854 /* We leave bad_p off ck_ambig because overload resolution considers
6855 it valid, it just fails when we try to perform it. So we need to
6856 check complain here, too. */
6858 {
6859 /* Call build_user_type_conversion again for the error. */
6867 }
6871 {
6872 /* Conversion to std::initializer_list<T>. */
6880 /* Convert all the elements. */
6882 {
6893 }
6894 /* Build up the array. */
6895 elttype = cp_build_qualified_type
6899 /* Take the address explicitly rather than via decay_conversion
6900 to avoid the error about taking the address of a temporary. */
6906 /* Build up the initializer_list object. Note: fail gracefully
6907 if the object cannot be completed because, for example, no
6908 definition is provided (c++/80956). */
6918 }
6922 {
6931 }
6934 complain);
6941 };
6951 {
6955 {
6957 {
6962 }
6964 }
6969 /* Don't introduce copies when passing arguments along to the inherited
6970 constructor. */
6972 && flag_new_inheriting_ctors
6978 /* Copy-list-initialization doesn't actually involve a copy. */
6981 /* Fall through. */
6984 {
6985 /* We are going to bind a reference directly to a base-class
6986 subobject of EXPR. */
6987 /* Build an expression for `*((base*) &expr)'. */
6991 }
6993 /* Copy-initialization where the cv-unqualified version of the source
6994 type is the same class as, or a derived class of, the class of the
6995 destination [is treated as direct-initialization]. [dcl.init] */
6998 /* This conversion is being done in the context of a user-defined
6999 conversion (i.e. the second step of copy-initialization), so
7000 don't allow any more. */
7002 else
7005 /* standard_conversion got LOOKUP_PREFER_RVALUE. */
7009 {
7014 }
7019 {
7023 {
7036 else
7043 }
7045 /* If necessary, create a temporary.
7047 VA_ARG_EXPR and CONSTRUCTOR expressions are special cases
7048 that need temporaries, even when their types are reference
7049 compatible with the type of reference being bound, so the
7050 upcoming call to cp_build_addr_expr doesn't fail. */
7054 {
7055 /* Otherwise, a temporary of type "cv1 T1" is created and
7056 initialized from the initializer expression using the rules
7057 for a non-reference copy-initialization (8.5). */
7066 {
7067 /* If the reference is volatile or non-const, we
7068 cannot create a temporary. */
7075 else
7079 }
7080 /* If the source is a packed field, and we must use a copy
7081 constructor, then building the target expr will require
7082 binding the field to the reference parameter to the
7083 copy constructor, and we'll end up with an infinite
7084 loop. If we can use a bitwise copy, then we'll be
7085 OK. */
7089 {
7093 }
7095 {
7098 }
7100 }
7102 /* Take the address of the thing to which we will bind the
7103 reference. */
7108 /* Convert it to a pointer to the type referred to by the
7109 reference. This will adjust the pointer if a derived to
7110 base conversion is being performed. */
7113 /* Convert the pointer to the desired reference type. */
7115 }
7121 /* ??? Should the address of a transaction-safe pointer point to the TM
7122 clone, and this conversion look up the primary function? */
7126 /* Warn about deprecated conversion if appropriate. */
7142 }
7151 else
7155 }
7157 /* ARG is being passed to a varargs function. Perform any conversions
7158 required. Return the converted value. */
7160 tree
7162 {
7163 tree arg_type;
7166 /* [expr.call]
7168 The lvalue-to-rvalue, array-to-pointer, and function-to-pointer
7169 standard conversions are performed. */
7172 /* [expr.call]
7174 If the argument has integral or enumeration type that is subject
7175 to the integral promotions (_conv.prom_), or a floating point
7176 type that is subject to the floating point promotion
7177 (_conv.fpprom_), the value of the argument is converted to the
7178 promoted type before the call. */
7183 {
7187 "implicit conversion from %qH to %qI when passing "
7191 }
7195 {
7197 {
7199 complain);
7209 }
7210 else
7212 }
7218 /* In a template (or ill-formed code), we can have an incomplete type
7219 even after require_complete_type_sfinae, in which case we don't know
7220 whether it has trivial copy or not. */
7223 {
7224 /* [expr.call] 5.2.2/7:
7225 Passing a potentially-evaluated argument of class type (Clause 9)
7226 with a non-trivial copy constructor or a non-trivial destructor
7227 with no corresponding parameter is conditionally-supported, with
7228 implementation-defined semantics.
7230 We support it as pass-by-invisible-reference, just like a normal
7231 value parameter.
7233 If the call appears in the context of a sizeof expression,
7234 it is not potentially-evaluated. */
7237 {
7241 "passing objects of non-trivially-copyable "
7243 arg_type);
7245 }
7246 /* Build up a real lvalue-to-rvalue conversion in case the
7247 copy constructor is trivial but not callable. */
7251 }
7254 }
7256 /* va_arg (EXPR, TYPE) is a builtin. Make sure it is not abused. */
7258 tree
7260 {
7262 {
7266 }
7276 {
7279 }
7283 {
7284 /* conditionally-supported behavior [expr.call] 5.2.2/7. Let's treat
7285 it as pass by invisible reference. */
7287 "receiving objects of non-trivially-copyable type %q#T "
7293 }
7297 /* Wrap the VA_ARG_EXPR in a TARGET_EXPR now so other code doesn't need to
7298 know how to handle it. */
7301 }
7303 /* TYPE has been given to va_arg. Apply the default conversions which
7304 would have happened when passed via ellipsis. Return the promoted
7305 type, or the passed type if there is no change. */
7307 tree
7309 {
7310 tree promote;
7312 /* Perform the array-to-pointer and function-to-pointer
7313 conversions. */
7321 }
7323 /* ARG is a default argument expression being passed to a parameter of
7324 the indicated TYPE, which is a parameter to FN. PARMNUM is the
7325 zero-based argument number. Do any required conversions. Return
7326 the converted value. */
7329 void
7333 void
7337 tree
7339 tsubst_flags_t complain)
7340 {
7342 tree t;
7344 /* See through clones. */
7346 /* And inheriting ctors. */
7350 /* Detect recursion. */
7353 {
7357 }
7359 /* If the ARG is an unparsed default argument expression, the
7360 conversion cannot be performed. */
7362 {
7367 }
7374 /* Due to:
7376 [dcl.fct.default]
7378 The names in the expression are bound, and the semantic
7379 constraints are checked, at the point where the default
7380 expressions appears.
7382 we must not perform access checks here. */
7384 /* We must make a copy of ARG, in case subsequent processing
7385 alters any part of it. */
7390 complain);
7397 }
7399 /* Returns the type which will really be used for passing an argument of
7400 type TYPE. */
7402 tree
7404 {
7405 /* Pass classes with copy ctors by invisible reference. */
7407 {
7409 /* There are no other pointers to this temporary. */
7411 }
7419 }
7421 /* Actually perform the appropriate conversion. */
7423 tree
7425 {
7426 tree bitfield_type;
7428 /* If VAL is a bitfield, then -- since it has already been converted
7429 to TYPE -- it cannot have a precision greater than TYPE.
7431 If it has a smaller precision, we must widen it here. For
7432 example, passing "int f:3;" to a function expecting an "int" will
7433 not result in any conversion before this point.
7435 If the precision is the same we must not risk widening. For
7436 example, the COMPONENT_REF for a 32-bit "long long" bitfield will
7437 often have type "int", even though the C++ type for the field is
7438 "long long". If the value is being passed to a function
7439 expecting an "int", then no conversions will be required. But,
7440 if we call convert_bitfield_to_declared_type, the bitfield will
7441 be converted to "long long". */
7448 ;
7449 /* Pass classes with copy ctors by invisible reference. */
7458 {
7460 {
7468 "argument of function call might be a candidate "
7470 }
7472 }
7474 }
7476 /* Returns non-zero iff FN is a function with magic varargs, i.e. ones for
7477 which just decay_conversion or no conversions at all should be done.
7478 This is true for some builtins which don't act like normal functions.
7479 Return 2 if no conversions at all should be done, 1 if just
7480 decay_conversion. Return 3 for special treatment of the 3rd argument
7481 for __builtin_*_overflow_p. */
7483 int
7485 {
7488 {
7503 }
7506 }
7508 /* Returns the decl of the dispatcher function if FN is a function version. */
7510 tree
7512 {
7522 {
7526 }
7531 }
7533 /* fn is a function version dispatcher that is marked used. Mark all the
7534 semantically identical function versions it will dispatch as used. */
7536 void
7538 {
7555 /* All semantically identical versions are chained. Traverse and mark each
7556 one of them as used. */
7559 {
7562 }
7563 }
7565 /* Build a call to "the copy constructor" for the type of A, even if it
7566 wouldn't be selected by normal overload resolution. Used for
7567 diagnostics. */
7569 static tree
7571 {
7582 }
7584 /* Return true iff T refers to a base field. */
7586 static bool
7588 {
7597 }
7599 /* We can't elide a copy from a function returning by value to a base
7600 subobject, as the callee might clobber tail padding. Return true iff this
7601 could be that case. */
7603 static bool
7605 {
7606 /* Copy elision only happens with a TARGET_EXPR. */
7610 /* It's safe to elide the copy for a class with no tail padding. */
7613 /* It's safe to elide the copy if we aren't initializing a base object. */
7617 /* build_compound_expr pushes COMPOUND_EXPR inside TARGET_EXPR. */
7621 {
7622 /* We'll end up copying from each of the arms of the COND_EXPR directly
7623 into the target, so look at them. */
7628 }
7631 }
7633 /* True iff C is a conversion that binds a reference to a prvalue. */
7635 static bool
7637 {
7654 }
7656 /* Call the trivial destructor for INSTANCE, which can be either an lvalue of
7657 class type or a pointer to class type. */
7659 tree
7661 {
7665 {
7666 no_clobber:
7668 }
7671 {
7675 }
7677 /* A trivial destructor should still clobber the object. */
7681 }
7683 /* Subroutine of the various build_*_call functions. Overload resolution
7684 has chosen a winning candidate CAND; build up a CALL_EXPR accordingly.
7685 ARGS is a TREE_LIST of the unconverted arguments to the call. FLAGS is a
7686 bitmask of various LOOKUP_* flags which apply to the call itself. */
7688 static tree
7690 {
7698 tree val;
7707 /* In a template, there is no need to perform all of the work that
7708 is normally done. We are only interested in the type of the call
7709 expression, i.e., the return type of the function. Any semantic
7710 errors will be deferred until the template is instantiated. */
7712 {
7714 tree return_type;
7720 else
7721 /* Otherwise set TREE_USED for the benefit of -Wunused-function.
7722 See PR80598. */
7729 else
7730 {
7733 tree arg;
7741 }
7751 }
7753 /* Give any warnings we noticed during overload resolution. */
7755 {
7759 }
7761 /* Core issue 2327: P0135 doesn't say how to handle the case where the
7762 argument to the copy constructor ends up being a prvalue after
7763 conversion. Let's do the normal processing, but pretend we aren't
7764 actually using the copy constructor. */
7772 {
7775 }
7777 /* OK, we're actually calling this inherited constructor; set its deletedness
7778 appropriately. We can get away with doing this here because calling is
7779 the only way to refer to a constructor. */
7783 /* Make =delete work with SFINAE. */
7785 {
7789 }
7792 {
7793 tree access_fn;
7794 /* If FN is a template function, two cases must be considered.
7795 For example:
7797 struct A {
7798 protected:
7799 template <class T> void f();
7800 };
7801 template <class T> struct B {
7802 protected:
7803 void g();
7804 };
7805 struct C : A, B<int> {
7806 using A::f; // #1
7807 using B<int>::g; // #2
7808 };
7810 In case #1 where `A::f' is a member template, DECL_ACCESS is
7811 recorded in the primary template but not in its specialization.
7812 We check access of FN using its primary template.
7814 In case #2, where `B<int>::g' has a DECL_TEMPLATE_INFO simply
7815 because it is a member of class template B, DECL_ACCESS is
7816 recorded in the specialization `B<int>::g'. We cannot use its
7817 primary template because `B<T>::g' and `B<int>::g' may have
7818 different access. */
7822 else
7827 }
7829 /* If we're checking for implicit delete, don't bother with argument
7830 conversions. */
7832 {
7836 /* Reject bad conversions now. */
7838 /* else continue to get conversion error. */
7839 }
7841 not_really_used:
7843 /* N3276 magic doesn't apply to nested calls. */
7846 /* No-Cleanup doesn't apply to nested calls either. */
7850 /* Find maximum size of vector to hold converted arguments. */
7857 /* The implicit parameters to a constructor are not considered by overload
7858 resolution, and must be of the proper type. */
7860 {
7861 tree object_arg;
7863 {
7866 }
7867 else
7868 {
7871 }
7874 /* We should never try to call the abstract constructor. */
7878 {
7882 }
7885 {
7886 /* The implicit move specified in 15.8.3/3 fails "...if the type of
7887 the first parameter of the selected constructor is not an rvalue
7888 reference to the object’s type (possibly cv-qualified)...." */
7895 }
7896 }
7897 /* Bypass access control for 'this' parameter. */
7899 {
7902 ? first_arg
7905 tree converted_arg;
7906 tree base_binfo;
7912 {
7914 {
7919 }
7920 else
7922 }
7924 /* See if the function member or the whole class type is declared
7925 final and the call can be devirtualized. */
7930 /* [class.mfct.nonstatic]: If a nonstatic member function of a class
7931 X is called for an object that is not of type X, or of a type
7932 derived from X, the behavior is undefined.
7934 So we can assume that anything passed as 'this' is non-null, and
7935 optimize accordingly. */
7937 /* Convert to the base in which the function was declared. */
7940 arg,
7943 /* Check that the base class is accessible. */
7946 {
7951 else
7953 }
7954 /* If fn was found by a using declaration, the conversion path
7955 will be to the derived class, not the base declaring fn. We
7956 must convert from derived to base. */
7967 else
7971 }
7976 {
7983 /* If the argument is NULL and used to (implicitly) instantiate a
7984 template function (and bind one of the template arguments to
7985 the type of 'long int'), we don't want to warn about passing NULL
7986 to non-pointer argument.
7987 For example, if we have this template function:
7989 template<typename T> void func(T x) {}
7991 we want to warn (when -Wconversion is enabled) in this case:
7993 void foo() {
7994 func<int>(NULL);
7995 }
7997 but not in this case:
7999 void foo() {
8000 func(NULL);
8001 }
8002 */
8009 /* Warn about initializer_list deduction that isn't currently in the
8010 working draft. */
8012 && flag_deduce_init_list
8016 {
8029 {
8037 }
8038 }
8040 /* Set user_conv_p on the argument conversions, so rvalue/base handling
8041 knows not to allow any more UDCs. This needs to happen after we
8042 process cand->warnings. */
8051 arg_complain);
8056 else
8058 }
8060 /* Default arguments */
8062 {
8068 complain);
8072 }
8074 /* Ellipsis */
8077 {
8080 {
8081 /* Do no conversions for certain magic varargs. */
8085 }
8087 /* For other magic varargs only do decay_conversion. */
8092 {
8093 /* Avoid infinite recursion trying to call A(...). */
8095 /* Try to call the actual copy constructor for a good error. */
8098 }
8099 else
8104 }
8109 /* Avoid to do argument-transformation, if warnings for format, and for
8110 nonnull are disabled. Just in case that at least one of them is active
8111 the check_function_arguments function might warn about something. */
8115 || warn_format
8116 || warn_suggest_attribute_format
8118 {
8122 {
8123 /* For -Wformat undo the implicit passing by hidden reference
8124 done by convert_arg_to_ellipsis. */
8128 else
8130 }
8134 }
8137 {
8138 /* Check for passing ellipsis arguments to an inherited constructor. We
8139 could handle this by open-coding the inherited constructor rather than
8140 defining it, but let's not bother now. */
8144 {
8146 {
8150 }
8152 }
8154 /* A base constructor inheriting from a virtual base doesn't get the
8155 inherited arguments, just this and __vtt. */
8158 }
8160 /* Avoid actually calling copy constructors and copy assignment operators,
8161 if possible. */
8168 /* It's unsafe to elide the constructor when handling
8169 a noexcept-expression, it may evaluate to the wrong
8170 value (c++/53025). */
8172 {
8173 tree targ;
8175 tree fa;
8178 /* Pull out the real argument, disregarding const-correctness. */
8180 /* Strip the reference binding for the constructor parameter. */
8184 /* But don't strip any other reference bindings; binding a temporary to a
8185 reference prevents copy elision. */
8191 {
8196 }
8197 else
8202 else
8205 /* In C++17 we shouldn't be copying a TARGET_EXPR except into a base
8206 subobject. */
8209 || force_elide
8210 /* It's from binding the ref parm to a packed field. */
8213 /* See unsafe_copy_elision_p. */
8220 /* [class.copy]: the copy constructor is implicitly defined even if the
8221 implementation elided its use. But don't warn about deprecation when
8222 eliding a temporary, as then no copy is actually performed. */
8227 {
8231 }
8232 else
8235 /* If we're creating a temp and we already have one, don't create a
8236 new one. If we're not creating a temp but we get one, use
8237 INIT_EXPR to collapse the temp into our target. Otherwise, if the
8238 ctor is trivial, do a bitwise copy with a simple TARGET_EXPR for a
8239 temp or an INIT_EXPR otherwise. */
8241 {
8246 }
8249 {
8254 }
8255 }
8259 {
8260 tree to = cp_stabilize_reference
8268 {
8269 /* Avoid copying empty classes. */
8272 }
8274 {
8278 "assignment from temporary initializer_list does not "
8282 }
8283 else
8284 {
8285 /* We must only copy the non-tail padding parts. */
8293 build_index_type
8302 }
8307 }
8309 {
8313 {
8316 no_cleanup_complain);
8317 else
8319 }
8320 }
8328 /* Warn if the built-in writes to an object of a non-trivial type. */
8335 /* Don't mess with virtual lookup in instantiate_non_dependent_expr;
8336 virtual functions can't be constexpr. */
8338 {
8339 tree t;
8346 complain);
8352 }
8353 else
8354 {
8358 }
8364 {
8366 /* build_new_op_1 will clear this when appropriate. */
8368 }
8370 {
8374 }
8376 }
8378 namespace
8379 {
8381 /* Return the DECL of the first non-static subobject of class TYPE
8382 that satisfies the predicate PRED or null if none can be found. */
8385 tree
8387 {
8392 {
8399 }
8405 {
8411 }
8414 }
8416 struct NonPublicField
8417 {
8419 {
8421 }
8422 };
8424 /* Return the DECL of the first non-public subobject of class TYPE
8425 or null if none can be found. */
8429 {
8431 }
8433 struct NonTrivialField
8434 {
8436 {
8438 }
8439 };
8441 /* Return the DECL of the first non-trivial subobject of class TYPE
8442 or null if none can be found. */
8446 {
8448 }
8452 /* Return true if all copy and move assignment operator overloads for
8453 class TYPE are trivial and at least one of them is not deleted and,
8454 when ACCESS is set, accessible. Return false otherwise. Set
8455 HASASSIGN to true when the TYPE has a (not necessarily trivial)
8456 copy or move assignment. */
8458 static bool
8460 {
8464 /* Iterate over overloads of the assignment operator, checking
8465 accessible copy assignments for triviality. */
8468 {
8471 /* Skip operators that aren't copy assignments. */
8478 /* Skip template assignment operators and deleted functions. */
8488 /* Break early when both properties have been determined. */
8491 }
8493 /* Return true if they're all trivial and one of the expressions
8494 TYPE() = TYPE() or TYPE() = (TYPE&)() is valid. */
8499 }
8501 /* Return true if all copy and move ctor overloads for class TYPE are
8502 trivial and at least one of them is not deleted and, when ACCESS is
8503 set, accessible. Return false otherwise. Set each element of HASCTOR[]
8504 to true when the TYPE has a (not necessarily trivial) default and copy
8505 (or move) ctor, respectively. */
8507 static bool
8509 {
8514 {
8517 /* Skip template constructors. */
8523 /* Skip ctors other than default, copy, and move. */
8539 /* Break early when both properties have been determined. */
8542 }
8545 }
8547 /* Issue a warning on a call to the built-in function FNDECL if it is
8548 a raw memory write whose destination is not an object of (something
8549 like) trivial or standard layout type with a non-deleted assignment
8550 and copy ctor. Detects const correctness violations, corrupting
8551 references, virtual table pointers, and bypassing non-trivial
8552 assignments. */
8554 static void
8557 {
8558 /* Except for bcopy where it's second, the destination pointer is
8559 the first argument for all functions handled here. Compute
8560 the index of the destination and source arguments. */
8570 /* Determine the type of the pointed-to object and whether it's
8571 a complete class type. */
8577 /* Check to see if the raw memory call is made by a non-static member
8578 function with THIS as the destination argument for the destination
8579 type. If so, and if the class has no non-trivial bases or members,
8580 be more permissive. */
8584 {
8589 /* FIXME: The following if statement is overly permissive (see
8590 bug 84851). Remove it in GCC 9. */
8602 }
8604 /* True if the class is trivial. */
8607 /* Set to true if DESTYPE has an accessible copy assignment. */
8609 /* True if all of the class' overloaded copy assignment operators
8610 are all trivial (and not deleted) and at least one of them is
8611 accessible. */
8614 /* Set to true if DESTTYPE has an accessible default and copy ctor,
8615 respectively. */
8618 /* True if all of the class' overloaded copy constructors are all
8619 trivial (and not deleted) and at least one of them is accessible. */
8622 /* Set FLD to the first private/protected member of the class. */
8625 /* The warning format string. */
8627 /* A suggested alternative to offer instead of the raw memory call.
8628 Empty string when none can be come up with. */
8633 {
8636 {
8637 /* Diagnose setting non-copy-assignable or non-trivial types,
8638 or types with a private member, to (potentially) non-zero
8639 bytes. Since the value of the bytes being written is unknown,
8640 suggest using assignment instead (if one exists). Also warn
8641 for writes into objects for which zero-initialization doesn't
8642 mean all bits clear (pointer-to-member data, where null is all
8643 bits set). Since the value being written is (most likely)
8644 non-zero, simply suggest assignment (but not copy assignment). */
8652 {
8655 "%qD writing to an object of type %#qT with "
8658 }
8664 }
8665 /* Fall through. */
8668 /* Similarly to the above, diagnose clearing non-trivial or non-
8669 standard layout objects, or objects of types with no assignmenmt.
8670 Since the value being written is known to be zero, suggest either
8671 copy assignment, copy ctor, or default ctor as an alternative,
8672 depending on what's available. */
8695 /* Determine the type of the source object. */
8699 else
8702 /* Since it's impossible to determine wheter the byte copy is
8703 being used in place of assignment to an existing object or
8704 as a substitute for initialization, assume it's the former.
8705 Determine the best alternative to use instead depending on
8706 what's not deleted. */
8727 srctype))
8728 {
8729 /* Warn when copying into a non-trivial object from an object
8730 of a different type other than void or char. */
8732 "%qD copying an object of non-trivial type "
8735 }
8740 srctype))
8741 {
8744 "%qD copying an object of type %#qT with "
8745 "%qs member %qD from an array of %#qT; use "
8748 }
8750 {
8755 /* Finally, warn on partial copies. */
8756 unsigned HOST_WIDE_INT typesize
8762 "a non-trivial type %#qT leaves %wu "
8765 "a non-trivial type %#qT leaves %wu "
8768 }
8783 {
8787 /* Finally, warn on reallocation into insufficient space. */
8789 "%qD moving an object of non-trivial type "
8792 sz);
8793 }
8798 }
8801 {
8805 else
8808 }
8812 }
8814 /* Build and return a call to FN, using NARGS arguments in ARGARRAY.
8815 This function performs no overload resolution, conversion, or other
8816 high-level operations. */
8818 tree
8820 tsubst_flags_t complain)
8821 {
8822 tree fndecl;
8824 /* Remember roughly where this call is. */
8831 /* Check that arguments to builtin functions match the expectations. */
8833 && !processing_template_decl
8836 {
8839 /* We need to take care that values to BUILT_IN_NORMAL
8840 are reduced. */
8847 }
8852 /* 5.2.2/11: If a function call is a prvalue of object type: if the
8853 function call is either the operand of a decltype-specifier or the
8854 right operand of a comma operator that is the operand of a
8855 decltype-specifier, a temporary object is not introduced for the
8856 prvalue. The type of the prvalue may be incomplete. */
8858 {
8864 {
8867 }
8868 }
8870 }
8872 /* Returns the value to use for the in-charge parameter when making a
8873 call to a function with the indicated NAME.
8875 FIXME:Can't we find a neater way to do this mapping? */
8877 tree
8879 {
8881 {
8885 }
8886 else
8887 {
8893 }
8896 }
8898 /* We've built up a constructor call RET. Complain if it delegates to the
8899 constructor we're currently compiling. */
8901 static void
8903 {
8909 }
8911 /* Build a call to a constructor, destructor, or an assignment
8912 operator for INSTANCE, an expression with class type. NAME
8913 indicates the special member function to call; *ARGS are the
8914 arguments. ARGS may be NULL. This may change ARGS. BINFO
8915 indicates the base of INSTANCE that is to be passed as the `this'
8916 parameter to the member function called.
8918 FLAGS are the LOOKUP_* flags to use when processing the call.
8920 If NAME indicates a complete object constructor, INSTANCE may be
8921 NULL_TREE. In this case, the caller will call build_cplus_new to
8922 store the newly constructed object into a VAR_DECL. */
8924 tree
8927 {
8928 tree fns;
8929 /* The type of the subobject to be constructed or destroyed. */
8930 tree class_type;
8932 tree ret;
8940 {
8943 /* Shortcut to avoid lazy destructor declaration. */
8945 }
8948 {
8949 /* Resolve the name. */
8954 }
8960 /* Handle the special case where INSTANCE is NULL_TREE. */
8963 else
8964 {
8965 /* Convert to the base class, if necessary. */
8968 {
8970 /* For constructors and destructors, either the base is
8971 non-virtual, or it is virtual but we are doing the
8972 conversion from a constructor or destructor for the
8973 complete object. In either case, we can convert
8974 statically. */
8976 else
8977 {
8978 /* However, for assignment operators, we must convert
8979 dynamically if the base is virtual. */
8983 }
8984 }
8985 }
8989 /* In C++17, "If the initializer expression is a prvalue and the
8990 cv-unqualified version of the source type is the same class as the class
8991 of the destination, the initializer expression is used to initialize the
8992 destination object." Handle that here to avoid doing overload
8993 resolution. */
8997 {
9007 && (same_type_ignoring_top_level_qualifiers_p
9009 {
9018 /* Avoid change of behavior on Wunused-var-2.C. */
9021 }
9022 }
9026 /* When making a call to a constructor or destructor for a subobject
9027 that uses virtual base classes, pass down a pointer to a VTT for
9028 the subobject. */
9032 {
9033 tree vtt;
9034 tree sub_vtt;
9036 /* If the current function is a complete object constructor
9037 or destructor, then we fetch the VTT directly.
9038 Otherwise, we look it up using the VTT we were given. */
9046 else
9050 {
9053 }
9056 }
9061 complain);
9072 }
9074 /* Return the NAME, as a C string. The NAME indicates a function that
9075 is a member of TYPE. *FREE_P is set to true if the caller must
9076 free the memory returned.
9078 Rather than go through all of this, we should simply set the names
9079 of constructors and destructors appropriately, and dispense with
9080 ctor_identifier, dtor_identifier, etc. */
9084 {
9087 /* Assume that we will not allocate memory. */
9089 /* Constructors and destructors are special. */
9091 {
9092 pretty_name
9094 /* For a destructor, add the '~'. */
9096 {
9098 /* Remember that we need to free the memory allocated. */
9100 }
9101 }
9103 {
9106 TFF_PLAIN_IDENTIFIER),
9107 NULL);
9108 /* Remember that we need to free the memory allocated. */
9110 }
9111 else
9115 }
9117 /* Build a call to "INSTANCE.FN (ARGS)". If FN_P is non-NULL, it will
9118 be set, upon return, to the function called. ARGS may be NULL.
9119 This may change ARGS. */
9121 static tree
9125 {
9130 tree optype;
9132 tree name;
9135 tree call;
9136 tree fn;
9139 tree orig_instance;
9140 tree orig_fns;
9146 /* We don't know what function we're going to call, yet. */
9155 {
9159 }
9164 /* Dismantle the baselink to collect all the information we need. */
9172 {
9176 }
9187 /* Under DR 147 A::A() is an invalid constructor call,
9188 not a functional cast. */
9190 {
9202 complain);
9204 }
9207 {
9212 }
9214 /* Process the argument list. */
9216 {
9221 }
9223 /* Consider the object argument to be used even if we end up selecting a
9224 static member function. */
9227 /* Figure out whether to skip the first argument for the error
9228 message we will display to users if an error occurs. We don't
9229 want to display any compiler-generated arguments. The "this"
9230 pointer hasn't been added yet. However, we must remove the VTT
9231 pointer if this is a call to a base-class constructor or
9232 destructor. */
9235 {
9236 /* Callers should explicitly indicate whether they want to ctor
9237 the complete object or just the part without virtual bases. */
9240 /* Remove the VTT pointer, if present. */
9245 /* It's OK to call destructors and constructors on cv-qualified
9246 objects. Therefore, convert the INSTANCE to the unqualified
9247 type, if necessary. */
9249 {
9253 }
9254 }
9255 else
9258 /* For the overload resolution we need to find the actual `this`
9259 that would be captured if the call turns out to be to a
9260 non-static member function. Do not actually capture it at this
9261 point. */
9263 /* Constructors don't use the enclosing 'this'. */
9265 else
9268 /* Get the high-water mark for the CONVERSION_OBSTACK. */
9271 /* The number of arguments artificial parms in ARGS; we subtract one because
9272 there's no 'this' in ARGS. */
9275 /* If CONSTRUCTOR_IS_DIRECT_INIT is set, this was a T{ } form
9276 initializer, not T({ }). */
9280 {
9287 /* If the initializer list has no elements and T is a class type with
9288 a default constructor, the object is value-initialized. Handle
9289 this here so we don't need to handle it wherever we use
9290 build_special_member_call. */
9293 /* For a user-provided default constructor, use the normal
9294 mechanisms so that protected access works. */
9299 /* If BASETYPE is an aggregate, we need to do aggregate
9300 initialization. */
9302 {
9305 }
9308 {
9314 }
9316 /* Otherwise go ahead with overload resolution. */
9321 }
9322 else
9331 {
9333 {
9340 else
9341 {
9346 {
9349 }
9357 }
9359 }
9361 }
9362 else
9363 {
9366 {
9369 tree arglist;
9372 {
9380 else
9386 }
9388 }
9389 else
9390 {
9398 {
9399 /* This is not an error, it is runtime undefined
9400 behavior. */
9409 fn);
9410 }
9415 {
9420 {
9421 /* We captured 'this' in the current lambda now that
9422 we know we really need it. */
9424 }
9426 /* We can't tell until instantiation time whether we can use
9428 else
9429 {
9432 fn);
9434 }
9435 }
9438 {
9439 /* Optimize away vtable lookup if we know that this
9440 function can't be overridden. We need to check if
9441 the context and the type where we found fn are the same,
9442 actually FN might be defined in a different class
9443 type because of a using-declaration. In this case, we
9444 do not want to perform a non-virtual call. */
9446 && same_type_ignoring_top_level_qualifiers_p
9452 /* Now we know what function is being called. */
9455 /* Build the actual CALL_EXPR. */
9457 /* In an expression of the form `a->f()' where `f' turns
9458 out to be a static member function, `a' is
9459 none-the-less evaluated. */
9463 {
9464 /* But avoid the implicit lvalue-rvalue conversion when 'a'
9465 is volatile. */
9470 }
9474 /* An explicit call of the form "x->~X()" has type
9475 "void". However, on platforms where destructors
9476 return "this" (i.e., those where
9477 targetm.cxx.cdtor_returns_this is true), such calls
9478 will appear to have a return value of pointer type
9479 to the low-level call machinery. We do not want to
9480 change the low-level machinery, since we want to be
9481 able to optimize "delete f()" on such platforms as
9482 "operator delete(~X(f()))" (rather than generating
9483 "t = f(), ~X(t), operator delete (t)"). */
9485 }
9486 }
9487 }
9490 {
9496 {
9499 }
9502 call = (build_min_non_dep_call_vec
9506 orig_args));
9511 }
9513 /* Free all the conversions we allocated. */
9520 }
9522 /* Wrapper for above. */
9524 tree
9528 {
9529 tree ret;
9535 }
9537 /* Returns true iff standard conversion sequence ICS1 is a proper
9538 subsequence of ICS2. */
9540 static bool
9542 {
9543 /* We can assume that a conversion of the same code
9544 between the same types indicates a subsequence since we only get
9545 here if the types we are converting from are the same. */
9552 {
9562 /* At this point, ICS1 cannot be a proper subsequence of
9563 ICS2. We can get a USER_CONV when we are comparing the
9564 second standard conversion sequence of two user conversion
9565 sequences. */
9580 }
9581 }
9583 /* Returns nonzero iff DERIVED is derived from BASE. The inputs may
9584 be any _TYPE nodes. */
9586 bool
9588 {
9592 /* We only allow proper derivation here. The DERIVED_FROM_P macro
9593 considers every class derived from itself. */
9596 }
9598 /* We build the ICS for an implicit object parameter as a pointer
9599 conversion sequence. However, such a sequence should be compared
9600 as if it were a reference conversion sequence. If ICS is the
9601 implicit conversion sequence for an implicit object parameter,
9602 modify it accordingly. */
9604 static void
9606 {
9608 {
9609 /* [over.match.funcs]
9611 For non-static member functions, the type of the
9612 implicit object parameter is "reference to cv X"
9613 where X is the class of which the function is a
9614 member and cv is the cv-qualification on the member
9615 function declaration. */
9617 tree reference_type;
9619 /* The `this' parameter is a pointer to a class type. Make the
9620 implicit conversion talk about a reference to that same class
9621 type. */
9634 }
9635 }
9637 /* If *ICS is a REF_BIND set *ICS to the remainder of the conversion,
9638 and return the initial reference binding conversion. Otherwise,
9639 leave *ICS unchanged and return NULL. */
9643 {
9645 {
9650 }
9653 }
9655 /* Compare two implicit conversion sequences according to the rules set out in
9656 [over.ics.rank]. Return values:
9658 1: ics1 is better than ics2
9659 -1: ics2 is better than ics1
9660 0: ics1 and ics2 are indistinguishable */
9662 static int
9664 {
9665 tree from_type1;
9666 tree from_type2;
9667 tree to_type1;
9668 tree to_type2;
9675 /* REF_BINDING is nonzero if the result of the conversion sequence
9676 is a reference type. In that case REF_CONV is the reference
9677 binding conversion. */
9681 /* Compare badness before stripping the reference conversion. */
9687 /* Handle implicit object parameters. */
9691 /* Handle reference parameters. */
9695 /* List-initialization sequence L1 is a better conversion sequence than
9696 list-initialization sequence L2 if L1 converts to
9697 std::initializer_list<X> for some X and L2 does not. */
9703 /* [over.ics.rank]
9705 When comparing the basic forms of implicit conversion sequences (as
9706 defined in _over.best.ics_)
9708 --a standard conversion sequence (_over.ics.scs_) is a better
9709 conversion sequence than a user-defined conversion sequence
9710 or an ellipsis conversion sequence, and
9712 --a user-defined conversion sequence (_over.ics.user_) is a
9713 better conversion sequence than an ellipsis conversion sequence
9714 (_over.ics.ellipsis_). */
9715 /* Use BAD_CONVERSION_RANK because we already checked for a badness
9716 mismatch. If both ICS are bad, we try to make a decision based on
9717 what would have happened if they'd been good. This is not an
9718 extension, we'll still give an error when we build up the call; this
9719 just helps us give a more helpful error message. */
9729 /* Both conversions are ellipsis conversions. */
9732 /* User-defined conversion sequence U1 is a better conversion sequence
9733 than another user-defined conversion sequence U2 if they contain the
9734 same user-defined conversion operator or constructor and if the sec-
9735 ond standard conversion sequence of U1 is better than the second
9736 standard conversion sequence of U2. */
9738 /* Handle list-conversion with the same code even though it isn't always
9739 ranked as a user-defined conversion and it doesn't have a second
9740 standard conversion sequence; it will still have the desired effect.
9741 Specifically, we need to do the reference binding comparison at the
9742 end of this function. */
9745 {
9761 {
9766 }
9767 else
9768 {
9769 /* For ambiguous or aggregate conversions, use the target type as
9770 a proxy for the conversion function. */
9773 }
9775 /* We can just fall through here, after setting up
9776 FROM_TYPE1 and FROM_TYPE2. */
9779 }
9780 else
9781 {
9785 /* We're dealing with two standard conversion sequences.
9787 [over.ics.rank]
9789 Standard conversion sequence S1 is a better conversion
9790 sequence than standard conversion sequence S2 if
9792 --S1 is a proper subsequence of S2 (comparing the conversion
9793 sequences in the canonical form defined by _over.ics.scs_,
9794 excluding any Lvalue Transformation; the identity
9795 conversion sequence is considered to be a subsequence of
9796 any non-identity conversion sequence */
9807 }
9809 /* One sequence can only be a subsequence of the other if they start with
9810 the same type. They can start with different types when comparing the
9811 second standard conversion sequence in two user-defined conversion
9812 sequences. */
9814 {
9819 }
9821 /* [over.ics.rank]
9823 Or, if not that,
9825 --the rank of S1 is better than the rank of S2 (by the rules
9826 defined below):
9828 Standard conversion sequences are ordered by their ranks: an Exact
9829 Match is a better conversion than a Promotion, which is a better
9830 conversion than a Conversion.
9832 Two conversion sequences with the same rank are indistinguishable
9833 unless one of the following rules applies:
9835 --A conversion that does not a convert a pointer, pointer to member,
9836 or std::nullptr_t to bool is better than one that does.
9838 The ICS_STD_RANK automatically handles the pointer-to-bool rule,
9839 so that we do not have to check it explicitly. */
9848 /* A conversion from scalar arithmetic type to complex is worse than a
9849 conversion between scalar arithmetic types. */
9856 {
9859 else
9861 }
9867 {
9872 }
9873 /* The rules for pointers to members A::* are just like the rules
9874 for pointers A*, except opposite: if B is derived from A then
9875 A::* converts to B::*, not vice versa. For that reason, we
9876 switch the from_ and to_ variables here. */
9883 {
9888 }
9893 {
9894 /* This was one of the pointer or pointer-like conversions.
9896 [over.ics.rank]
9898 --If class B is derived directly or indirectly from class A,
9899 conversion of B* to A* is better than conversion of B* to
9900 void*, and conversion of A* to void* is better than
9901 conversion of B* to void*. */
9904 {
9906 deref_from_type2))
9909 deref_from_type1))
9911 }
9914 {
9916 {
9918 {
9920 deref_to_type1))
9922 }
9923 /* We know that DEREF_TO_TYPE1 is `void' here. */
9925 deref_to_type2))
9927 }
9928 }
9931 {
9932 /* [over.ics.rank]
9934 --If class B is derived directly or indirectly from class A
9935 and class C is derived directly or indirectly from B,
9937 --conversion of C* to B* is better than conversion of C* to
9938 A*,
9940 --conversion of B* to A* is better than conversion of C* to
9941 A* */
9943 {
9945 deref_to_type2))
9948 deref_to_type1))
9950 }
9952 {
9954 deref_from_type1))
9957 deref_from_type2))
9959 }
9960 }
9961 }
9964 {
9967 /* [over.ics.rank]
9969 --binding of an expression of type C to a reference of type
9970 B& is better than binding an expression of type C to a
9971 reference of type A&
9973 --conversion of C to B is better than conversion of C to A, */
9976 {
9981 }
9982 }
9985 {
9988 /* [over.ics.rank]
9990 --binding of an expression of type B to a reference of type
9991 A& is better than binding an expression of type C to a
9992 reference of type A&,
9994 --conversion of B to A is better than conversion of C to A */
9997 {
10002 }
10003 }
10005 /* [over.ics.rank]
10007 --S1 and S2 differ only in their qualification conversion and yield
10008 similar types T1 and T2 (_conv.qual_), respectively, and the cv-
10009 qualification signature of type T1 is a proper subset of the cv-
10010 qualification signature of type T2 */
10014 {
10018 }
10020 /* [over.ics.rank]
10022 --S1 and S2 are reference bindings (_dcl.init.ref_) and neither refers
10023 to an implicit object parameter of a non-static member function
10024 declared without a ref-qualifier, and either S1 binds an lvalue
10025 reference to an lvalue and S2 binds an rvalue reference or S1 binds an
10026 rvalue reference to an rvalue and S2 binds an lvalue reference (C++0x
10027 draft standard, 13.3.3.2)
10029 --S1 and S2 are reference bindings (_dcl.init.ref_), and the
10030 types to which the references refer are the same type except for
10031 top-level cv-qualifiers, and the type to which the reference
10032 initialized by S2 refers is more cv-qualified than the type to
10033 which the reference initialized by S1 refers.
10035 DR 1328 [over.match.best]: the context is an initialization by
10036 conversion function for direct reference binding (13.3.1.6) of a
10037 reference to function type, the return type of F1 is the same kind of
10038 reference (i.e. lvalue or rvalue) as the reference being initialized,
10039 and the return type of F2 is not. */
10042 {
10049 {
10053 /* Don't prefer a bad conversion that drops cv-quals to a bad
10054 conversion with the wrong rvalueness. */
10058 }
10061 {
10065 {
10066 /* Prefer the one that drops fewer cv-quals. */
10071 }
10073 }
10074 }
10076 /* Neither conversion sequence is better than the other. */
10078 }
10080 /* The source type for this standard conversion sequence. */
10082 static tree
10084 {
10086 {
10091 }
10093 }
10095 /* Note a warning about preferring WINNER to LOSER. We do this by storing
10096 a pointer to LOSER and re-running joust to produce the warning if WINNER
10097 is actually used. */
10099 static void
10101 {
10107 }
10109 /* Compare two candidates for overloading as described in
10110 [over.match.best]. Return values:
10112 1: cand1 is better than cand2
10113 -1: cand2 is better than cand1
10114 0: cand1 and cand2 are indistinguishable */
10116 static int
10118 tsubst_flags_t complain)
10119 {
10125 /* Candidates that involve bad conversions are always worse than those
10126 that don't. */
10132 /* If we have two pseudo-candidates for conversions to the same type,
10133 or two candidates for the same function, arbitrarily pick one. */
10138 /* Prefer a non-deleted function over an implicitly deleted move
10139 constructor or assignment operator. This differs slightly from the
10140 wording for issue 1402 (which says the move op is ignored by overload
10141 resolution), but this way produces better error messages. */
10145 {
10152 }
10154 /* a viable function F1
10155 is defined to be a better function than another viable function F2 if
10156 for all arguments i, ICSi(F1) is not a worse conversion sequence than
10157 ICSi(F2), and then */
10159 /* for some argument j, ICSj(F1) is a better conversion sequence than
10160 ICSj(F2) */
10162 /* For comparing static and non-static member functions, we ignore
10163 the implicit object parameter of the non-static function. The
10164 standard says to pretend that the static function has an object
10165 parm, but that won't work with operator overloading. */
10168 {
10174 /* We're comparing a near-match list constructor and a near-match
10175 non-list constructor. Just treat them as unordered. */
10182 else
10183 {
10186 }
10187 }
10190 {
10196 {
10198 && warn_sign_promo
10210 {
10217 else
10222 {
10226 }
10227 else
10229 }
10232 {
10235 }
10237 }
10238 }
10240 /* warn about confusing overload resolution for user-defined conversions,
10241 either between a constructor and a conversion op, or between two
10242 conversion ops. */
10247 {
10253 else
10256 /* We don't want to complain about `X::operator T1 ()'
10257 beating `X::operator T2 () const', when T2 is a no less
10258 cv-qualified version of T1. */
10261 {
10266 {
10269 }
10272 }
10273 else
10279 {
10286 {
10288 }
10289 }
10290 else
10292 }
10297 /* DR 495 moved this tiebreaker above the template ones. */
10298 /* or, if not that,
10299 the context is an initialization by user-defined conversion (see
10300 _dcl.init_ and _over.match.user_) and the standard conversion
10301 sequence from the return type of F1 to the destination type (i.e.,
10302 the type of the entity being initialized) is a better conversion
10303 sequence than the standard conversion sequence from the return type
10304 of F2 to the destination type. */
10307 {
10311 }
10313 /* or, if not that,
10314 F1 is a non-template function and F2 is a template function
10315 specialization. */
10322 /* or, if not that,
10323 F1 and F2 are template functions and the function template for F1 is
10324 more specialized than the template for F2 according to the partial
10325 ordering rules. */
10328 {
10329 winner = more_specialized_fn
10332 /* [temp.func.order]: The presence of unused ellipsis and default
10333 arguments has no effect on the partial ordering of function
10334 templates. add_function_candidate() will not have
10335 counted the "this" argument for constructors. */
10339 }
10341 // C++ Concepts
10342 // or, if not that, F1 is more constrained than F2.
10344 {
10348 }
10350 /* F1 is generated from a deduction-guide (13.3.1.8) and F2 is not */
10352 {
10354 /* We distinguish between candidates from an explicit deduction guide and
10355 candidates built from a constructor based on DECL_ARTIFICIAL. */
10362 {
10363 /* Prefer the special copy guide over a declared copy/move
10364 constructor. */
10370 /* Prefer a candidate generated from a non-template constructor. */
10375 }
10376 }
10378 /* F1 is a member of a class D, F2 is a member of a base class B of D, and
10379 for all arguments the corresponding parameters of F1 and F2 have the same
10380 type (CWG 2273/2277). */
10385 {
10399 {
10401 {
10406 }
10409 }
10410 }
10412 /* Check whether we can discard a builtin candidate, either because we
10413 have two identical ones or matching builtin and non-builtin candidates.
10415 (Pedantically in the latter case the builtin which matched the user
10416 function should not be added to the overload set, but we spot it here.
10418 [over.match.oper]
10419 ... the builtin candidates include ...
10420 - do not have the same parameter type list as any non-template
10421 non-member candidate. */
10424 {
10430 {
10432 /* Two built-in candidates; arbitrarily pick one. */
10435 /* cand1 is built-in; prefer cand2. */
10437 else
10438 /* cand2 is built-in; prefer cand1. */
10440 }
10441 }
10443 /* For candidates of a multi-versioned function, make the version with
10444 the highest priority win. This version will be checked for dispatching
10445 first. If this version can be inlined into the caller, the front-end
10446 will simply make a direct call to this function. */
10452 {
10458 /* Check if cand1->fn and cand2->fn are versions of the same function. It
10459 is possible that cand1->fn and cand2->fn are function versions but of
10460 different functions. Check types to see if they are versions of the same
10461 function. */
10464 {
10465 /* Always make the version with the higher priority, more
10466 specialized, win. */
10470 else
10472 }
10473 }
10475 /* If the two function declarations represent the same function (this can
10476 happen with declarations in multiple scopes and arg-dependent lookup),
10477 arbitrarily choose one. But first make sure the default args we're
10478 using match. */
10481 {
10488 {
10489 /* Don't crash if the fn is variadic. */
10494 }
10502 {
10505 {
10507 {
10509 {
10511 "default argument mismatch in "
10513 {
10518 }
10519 }
10520 else
10522 }
10523 else
10526 }
10529 }
10532 }
10534 tweak:
10536 /* Extension: If the worst conversion for one candidate is worse than the
10537 worst conversion for the other, take the first. */
10539 {
10544 {
10549 }
10555 {
10556 /* Don't choose a deleted function over ambiguity. */
10560 {
10562 "ISO C++ says that these are ambiguous, even "
10563 "though the worst conversion for the first is better than "
10567 }
10568 else
10571 }
10572 }
10576 }
10578 /* Given a list of candidates for overloading, find the best one, if any.
10579 This algorithm has a worst case of O(2n) (winner is last), and a best
10580 case of O(n/2) (totally ambiguous); much better than a sorting
10581 algorithm. */
10585 {
10590 /* Walk through the list once, comparing each current champ to the next
10591 candidate, knocking out a candidate or two with each comparison. */
10594 {
10598 else
10599 {
10601 {
10606 }
10607 else
10608 {
10611 }
10614 }
10615 }
10617 /* Make sure the champ is better than all the candidates it hasn't yet
10618 been compared to. */
10621 challenger != champ
10624 {
10628 }
10631 }
10633 /* Returns nonzero if things of type FROM can be converted to TO. */
10635 bool
10637 {
10639 /* implicit_conversion only considers user-defined conversions
10640 if it has an expression for the call argument list. */
10644 }
10646 /* Returns nonzero if things of type FROM can be converted to TO with a
10647 standard conversion. */
10649 bool
10651 {
10653 }
10655 /* Returns nonzero if ARG (of type FROM) can be converted to TO. */
10657 bool
10659 tsubst_flags_t complain)
10660 {
10665 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10667 /* We want to discard any access checks done for this test,
10668 as we might not be in the appropriate access context and
10669 we'll do the check again when we actually perform the
10670 conversion. */
10677 /* Discard the access checks now. */
10679 /* Free all the conversions we allocated. */
10683 }
10685 /* Like can_convert_arg, but allows dubious conversions as well. */
10687 bool
10689 tsubst_flags_t complain)
10690 {
10694 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10696 /* Try to perform the conversion. */
10699 /* Free all the conversions we allocated. */
10703 }
10705 /* Convert EXPR to TYPE. Return the converted expression.
10707 Note that we allow bad conversions here because by the time we get to
10708 this point we are committed to doing the conversion. If we end up
10709 doing a bad conversion, convert_like will complain. */
10711 tree
10714 {
10721 else
10727 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10735 {
10737 {
10738 /* If expr has unknown type, then it is an overloaded function.
10739 Call instantiate_type to get good error messages. */
10744 else
10747 }
10749 }
10751 {
10752 /* In a template, we are only concerned about determining the
10753 type of non-dependent expressions, so we do not have to
10754 perform the actual conversion. But for initializers, we
10755 need to be able to perform it at instantiation
10756 (or instantiate_non_dependent_expr) time. */
10760 }
10761 else
10764 /* Free all the conversions we allocated. */
10768 }
10770 tree
10772 {
10774 LOOKUP_IMPLICIT);
10775 }
10777 /* Convert EXPR to TYPE (as a direct-initialization) if that is
10778 permitted. If the conversion is valid, the converted expression is
10779 returned. Otherwise, NULL_TREE is returned, except in the case
10780 that TYPE is a class type; in that case, an error is issued. If
10781 C_CAST_P is true, then this direct-initialization is taking
10782 place as part of a static_cast being attempted as part of a C-style
10783 cast. */
10785 tree
10787 tree expr,
10789 tsubst_flags_t complain)
10790 {
10796 /* [dcl.init]
10798 If the destination type is a (possibly cv-qualified) class type:
10800 -- If the initialization is direct-initialization ...,
10801 constructors are considered. ... If no constructor applies, or
10802 the overload resolution is ambiguous, the initialization is
10803 ill-formed. */
10805 {
10811 }
10813 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10817 c_cast_p,
10822 {
10823 /* In a template, we are only concerned about determining the
10824 type of non-dependent expressions, so we do not have to
10825 perform the actual conversion. But for initializers, we
10826 need to be able to perform it at instantiation
10827 (or instantiate_non_dependent_expr) time. */
10830 }
10831 else
10834 c_cast_p,
10835 complain);
10837 /* Free all the conversions we allocated. */
10841 }
10843 /* When initializing a reference that lasts longer than a full-expression,
10844 this special rule applies:
10846 [class.temporary]
10848 The temporary to which the reference is bound or the temporary
10849 that is the complete object to which the reference is bound
10850 persists for the lifetime of the reference.
10852 The temporaries created during the evaluation of the expression
10853 initializing the reference, except the temporary to which the
10854 reference is bound, are destroyed at the end of the
10855 full-expression in which they are created.
10857 In that case, we store the converted expression into a new
10858 VAR_DECL in a new scope.
10860 However, we want to be careful not to create temporaries when
10861 they are not required. For example, given:
10863 struct B {};
10864 struct D : public B {};
10865 D f();
10866 const B& b = f();
10868 there is no need to copy the return value from "f"; we can just
10869 extend its lifetime. Similarly, given:
10871 struct S {};
10872 struct T { operator S(); };
10873 T t;
10874 const S& s = t;
10876 we can extend the lifetime of the return value of the conversion
10877 operator.
10879 The next several functions are involved in this lifetime extension. */
10881 /* DECL is a VAR_DECL or FIELD_DECL whose type is a REFERENCE_TYPE. The
10882 reference is being bound to a temporary. Create and return a new
10883 VAR_DECL with the indicated TYPE; this variable will store the value to
10884 which the reference is bound. */
10886 tree
10888 {
10891 /* Register the variable. */
10894 {
10895 /* Namespace-scope or local static; give it a mangled name. */
10896 /* FIXME share comdat with decl? */
10907 }
10908 else
10909 /* Create a new cleanup level if necessary. */
10913 }
10915 /* EXPR is the initializer for a variable DECL of reference or
10916 std::initializer_list type. Create, push and return a new VAR_DECL
10917 for the initializer so that it will live as long as DECL. Any
10918 cleanup for the new variable is returned through CLEANUP, and the
10919 code to initialize the new variable is returned through INITP. */
10921 static tree
10924 {
10925 tree init;
10926 tree type;
10927 tree var;
10929 /* Create the temporary variable. */
10933 /* If the rvalue is the result of a function call it will be
10934 a TARGET_EXPR. If it is some other construct (such as a
10935 member access expression where the underlying object is
10936 itself the result of a function call), turn it into a
10937 TARGET_EXPR here. It is important that EXPR be a
10938 TARGET_EXPR below since otherwise the INIT_EXPR will
10939 attempt to make a bitwise copy of EXPR to initialize
10940 VAR. */
10946 {
10950 }
10952 /* Recursively extend temps in this initializer. */
10956 /* Any reference temp has a non-trivial initializer. */
10959 /* If the initializer is constant, put it in DECL_INITIAL so we get
10960 static initialization and use in constant expressions. */
10962 /* As in store_init_value. */
10965 {
10967 {
10968 /* 5.19 says that a constant expression can include an
10969 lvalue-rvalue conversion applied to "a glvalue of literal type
10970 that refers to a non-volatile temporary object initialized
10971 with a constant expression". Rather than try to communicate
10972 that this VAR_DECL is a temporary, just mark it constexpr. */
10977 }
10980 }
10981 else
10982 /* Create the INIT_EXPR that will initialize the temporary
10983 variable. */
10986 {
10991 else
10992 {
10996 }
10998 /* We must be careful to destroy the temporary only
10999 after its initialization has taken place. If the
11000 initialization throws an exception, then the
11001 destructor should not be run. We cannot simply
11002 transform INIT into something like:
11004 (INIT, ({ CLEANUP_STMT; }))
11006 because emit_local_var always treats the
11007 initializer as a full-expression. Thus, the
11008 destructor would run too early; it would run at the
11009 end of initializing the reference variable, rather
11010 than at the end of the block enclosing the
11011 reference variable.
11013 The solution is to pass back a cleanup expression
11014 which the caller is responsible for attaching to
11015 the statement tree. */
11016 }
11017 else
11018 {
11021 {
11024 tls_aggregates);
11025 else
11027 static_aggregates);
11028 }
11029 else
11030 /* Check whether the dtor is callable. */
11032 }
11033 /* Avoid -Wunused-variable warning (c++/38958). */
11040 }
11042 /* Convert EXPR to the indicated reference TYPE, in a way suitable for
11043 initializing a variable of that TYPE. */
11045 tree
11048 {
11056 /* Get the high-water mark for the CONVERSION_OBSTACK. */
11062 {
11064 {
11073 else
11077 }
11079 }
11082 /* Perform the conversion. */
11085 /* We gave an error in build_user_type_conversion_1. */
11087 else
11090 /* Free all the conversions we allocated. */
11094 }
11096 /* Subroutine of extend_ref_init_temps. Possibly extend one initializer,
11097 which is bound either to a reference or a std::initializer_list. */
11099 static tree
11101 {
11106 {
11110 }
11113 /* Deal with binding to a subobject. */
11119 {
11127 }
11129 }
11131 /* INIT is part of the initializer for DECL. If there are any
11132 reference or initializer lists being initialized, extend their
11133 lifetime to match that of DECL. */
11135 tree
11137 {
11143 else
11144 {
11149 {
11151 {
11152 /* The temporary array underlying a std::initializer_list
11153 is handled like a reference temporary. */
11157 }
11158 else
11159 {
11165 }
11169 }
11170 }
11173 }
11175 /* Returns true iff an initializer for TYPE could contain temporaries that
11176 need to be extended because they are bound to references or
11177 std::initializer_list. */
11179 bool
11181 {
11186 {
11193 }
11195 }
11197 /* Returns true iff TYPE is some variant of std::initializer_list. */
11199 bool
11201 {
11206 /* Look through typedefs. */
11211 }
11213 /* Returns true iff DECL is a list constructor: i.e. a constructor which
11214 will accept an argument list of a single std::initializer_list<T>. */
11216 bool
11218 {
11220 tree arg;
11232 /* There are more non-defaulted parms. */
11236 }