| blob | fd6528fcaebe70abc3847ced464e8554f6b37403 |
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. */
98 /* If KIND is ck_ptr or ck_pmem, true to indicate that a conversion
99 from a pointer-to-derived to pointer-to-base is being performed. */
101 /* If KIND is ck_ref_bind, true when either an lvalue reference is
102 being bound to an lvalue expression or an rvalue reference is
103 being bound to an rvalue expression. If KIND is ck_rvalue,
104 true when we are treating an lvalue as an rvalue (12.8p33). If
105 KIND is ck_base, always false. If ck_identity, we will be
106 binding a reference directly. */
109 /* The type of the expression resulting from the conversion. */
110 tree type;
112 /* The next conversion in the chain. Since the conversions are
113 arranged from outermost to innermost, the NEXT conversion will
114 actually be performed before this conversion. This variant is
115 used only when KIND is neither ck_identity, ck_ambig nor
116 ck_list. Please use the next_conversion function instead
117 of using this field directly. */
119 /* The expression at the beginning of the conversion chain. This
120 variant is used only if KIND is ck_identity or ck_ambig. */
121 tree expr;
122 /* The array of conversions for an initializer_list, so this
123 variant is used only when KIN D is ck_list. */
126 /* The function candidate corresponding to this conversion
127 sequence. This field is only used if KIND is ck_user. */
129 };
131 #define CONVERSION_RANK(NODE) \
132 ((NODE)->bad_p ? cr_bad \
133 : (NODE)->ellipsis_p ? cr_ellipsis \
134 : (NODE)->user_conv_p ? cr_user \
135 : (NODE)->rank)
137 #define BAD_CONVERSION_RANK(NODE) \
138 ((NODE)->ellipsis_p ? cr_ellipsis \
139 : (NODE)->user_conv_p ? cr_user \
140 : (NODE)->rank)
149 tsubst_flags_t);
154 #define convert_like(CONV, EXPR, COMPLAIN) \
155 convert_like_real ((CONV), (EXPR), NULL_TREE, 0, \
158 #define convert_like_with_context(CONV, EXPR, FN, ARGNO, COMPLAIN ) \
159 convert_like_real ((CONV), (EXPR), (FN), (ARGNO), \
167 tsubst_flags_t);
179 static void add_builtin_candidates
182 static void add_builtin_candidate
186 static void build_builtin_candidate
196 tsubst_flags_t);
198 tsubst_flags_t);
218 tsubst_flags_t);
222 /* Returns nonzero iff the destructor name specified in NAME matches BASETYPE.
223 NAME can take many forms... */
225 bool
227 {
228 /* Just accept something we've already complained about. */
237 {
242 else
244 }
245 else
246 {
247 /* In the case of:
249 template <class T> struct S { ~S(); };
250 int i;
251 i.~S();
253 NAME will be a class template. */
256 }
261 }
263 /* We want the address of a function or method. We avoid creating a
264 pointer-to-member function. */
266 tree
268 {
271 /* We have to do these by hand to avoid real pointer to member
272 functions. */
274 {
276 {
280 complain);
281 }
283 }
284 else
288 }
290 /* Build a CALL_EXPR, we can handle FUNCTION_TYPEs, METHOD_TYPEs, or
291 POINTER_TYPE to those. Note, pointer to member function types
292 (TYPE_PTRMEMFUNC_P) must be handled by our callers. There are
293 two variants. build_call_a is the primitive taking an array of
294 arguments, while build_call_n is a wrapper that handles varargs. */
296 tree
298 {
301 else
302 {
312 }
313 }
315 /* Update various flags in cfun and the call itself based on what is being
316 called. Split out of build_call_a so that bot_manip can use it too. */
318 void
320 {
324 /* We check both the decl and the type; a function may be known not to
325 throw without being declared throw(). */
339 }
341 tree
343 {
344 tree decl;
345 tree result_type;
346 tree fntype;
356 /* An rvalue has no cv-qualifiers. */
367 {
368 /* We invoke build_call directly for several library
369 functions. These may have been declared normally if
370 we're building libgcc, so we can't just check
371 DECL_ARTIFICIAL. */
376 }
382 /* Don't pass empty class objects by value. This is useful
383 for tags in STL, which are used to control overload resolution.
384 We don't need to handle other cases of copying empty classes. */
387 {
391 {
395 }
396 }
399 }
401 /* New overloading code. */
408 };
410 /* Information for providing diagnostics about why overloading failed. */
413 rr_none,
414 rr_arity,
415 rr_explicit_conversion,
416 rr_template_conversion,
417 rr_arg_conversion,
418 rr_bad_arg_conversion,
419 rr_template_unification,
420 rr_invalid_copy,
421 rr_inherited_ctor,
422 rr_constraint_failure
423 };
426 /* The index of the argument, 0-based. */
428 /* The actual argument or its type. */
429 tree from;
430 /* The type of the parameter. */
431 tree to_type;
432 };
437 /* Information about an arity mismatch. */
439 /* The expected number of arguments. */
441 /* The actual number of arguments in the call. */
443 /* Whether the call was a varargs call. */
446 /* Information about an argument conversion mismatch. */
448 /* Same, but for bad argument conversions. */
450 /* Information about template unification failures. These are the
451 parameters passed to fn_type_unification. */
453 tree tmpl;
454 tree explicit_targs;
458 tree return_type;
459 unification_kind_t strict;
462 /* Information about template instantiation failures. These are the
463 parameters passed to instantiate_template. */
465 tree tmpl;
466 tree targs;
469 };
472 /* The FUNCTION_DECL that will be called if this candidate is
473 selected by overload resolution. */
474 tree fn;
475 /* If not NULL_TREE, the first argument to use when calling this
476 function. */
477 tree first_arg;
478 /* The rest of the arguments to use when calling this function. If
479 there are no further arguments this may be NULL or it may be an
480 empty vector. */
482 /* The implicit conversion sequences for each of the arguments to
483 FN. */
485 /* The number of implicit conversion sequences. */
487 /* If FN is a user-defined conversion, the standard conversion
488 sequence from the type returned by FN to the desired destination
489 type. */
492 /* If FN is a member function, the binfo indicating the path used to
493 qualify the name of FN at the call site. This path is used to
494 determine whether or not FN is accessible if it is selected by
495 overload resolution. The DECL_CONTEXT of FN will always be a
496 (possibly improper) base of this binfo. */
497 tree access_path;
498 /* If FN is a non-static member function, the binfo indicating the
499 subobject to which the `this' pointer should be converted if FN
500 is selected by overload resolution. The type pointed to by
501 the `this' pointer must correspond to the most derived class
502 indicated by the CONVERSION_PATH. */
503 tree conversion_path;
504 tree template_decl;
505 tree explicit_targs;
510 /* The flags active in add_candidate. */
512 };
514 /* Returns true iff T is a null pointer constant in the sense of
515 [conv.ptr]. */
517 bool
519 {
522 /* [conv.ptr]
524 A null pointer constant is an integral constant expression
525 (_expr.const_) rvalue of integer type that evaluates to zero or
526 an rvalue of type std::nullptr_t. */
531 {
534 /* Core issue 903 says only literal 0 is a null pointer constant. */
541 }
543 {
548 }
551 }
553 /* Returns true iff T is a null member pointer value (4.11). */
555 bool
557 {
566 else
568 }
570 /* Returns nonzero if PARMLIST consists of only default parms,
571 ellipsis, and/or undeduced parameter packs. */
573 bool
575 {
582 }
584 /* Allocate N bytes of memory from the conversion obstack. The memory
585 is zeroed before being returned. */
589 {
592 {
595 }
599 }
601 /* Allocate rejection reasons. */
605 {
610 }
614 {
620 }
624 {
631 }
635 {
642 }
646 {
652 }
656 {
662 }
669 {
676 /* Copy args to our own storage. */
684 }
688 {
690 }
694 {
697 }
701 {
704 }
706 // Build a constraint failure record, saving information into the
707 // template_instantiation field of the rejection. If FN is not a template
708 // declaration, the TMPL member is the FN declaration and TARGS is empty.
712 {
715 {
718 }
719 else
720 {
723 }
725 }
727 /* Dynamically allocate a conversion. */
731 {
736 }
738 /* Make sure that all memory on the conversion obstack has been
739 freed. */
741 void
743 {
747 }
749 /* Dynamically allocate an array of N conversions. */
753 {
755 }
759 {
763 /* Note that the caller is responsible for filling in t->cand for
764 user-defined conversions. */
770 {
787 }
793 }
795 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
796 specialization of std::initializer_list<T>, if such a conversion is
797 possible. */
801 {
807 tree val;
809 /* Within a list-initialization we can have more user-defined
810 conversions. */
812 /* But no narrowing conversions. */
815 /* Can't make an array of these types. */
822 {
823 conversion *sub
830 }
838 {
846 }
849 }
851 /* Return the next conversion of the conversion chain (if applicable),
852 or NULL otherwise. Please use this function instead of directly
853 accessing fields of struct conversion. */
857 {
864 }
866 /* Subroutine of build_aggr_conv: check whether CTOR, a braced-init-list,
867 is a valid aggregate initializer for array type ATYPE. */
869 static bool
871 {
875 {
881 else
883 complain);
886 }
888 }
890 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
891 aggregate class, if such a conversion is possible. */
895 {
901 /* We already called reshape_init in implicit_conversion. */
903 /* The conversions within the init-list aren't affected by the enclosing
904 context; they're always simple copy-initialization. */
908 {
910 tree val;
918 /* Value-initialization of reference is ill-formed. */
920 else
921 {
925 }
931 else
933 complain);
940 }
952 }
954 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
955 array type, if such a conversion is possible. */
959 {
964 tree val;
969 /* We might need to propagate the size from the element to the array. */
974 {
978 }
983 {
984 conversion *sub
996 }
1005 }
1007 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
1008 complex type, if such a conversion is possible. */
1012 tsubst_flags_t complain)
1013 {
1018 tree val;
1029 {
1030 conversion *sub
1042 }
1051 }
1053 /* Build a representation of the identity conversion from EXPR to
1054 itself. The TYPE should match the type of EXPR, if EXPR is non-NULL. */
1058 {
1066 }
1068 /* Converting from EXPR to TYPE was ambiguous in the sense that there
1069 were multiple user-defined conversions to accomplish the job.
1070 Build a conversion that indicates that ambiguity. */
1074 {
1082 }
1084 tree
1086 {
1090 }
1092 /* Returns the standard conversion path (see [conv]) from type FROM to type
1093 TO, if any. For proper handling of null pointer constants, you must
1094 also pass the expression EXPR to convert from. If C_CAST_P is true,
1095 this conversion is coming from a C-style cast. */
1100 {
1104 tree qualified_to;
1108 {
1111 }
1117 {
1119 {
1125 }
1127 {
1128 /* Necessary for eg, TEMPLATE_ID_EXPRs (c++/50961). */
1131 }
1132 }
1139 {
1143 }
1144 /* Wrapping a ck_rvalue around a class prvalue (as a result of using
1145 obvalue_p) seems odd, since it's already a prvalue, but that's how we
1146 express the copy constructor call required by copy-initialization. */
1148 {
1150 {
1151 tree bitfield_type;
1154 {
1157 }
1158 }
1161 /* Tell convert_like_real to set LOOKUP_PREFER_RVALUE. */
1163 }
1165 /* Allow conversion between `__complex__' data types. */
1167 {
1168 /* The standard conversion sequence to convert FROM to TO is
1169 the standard conversion sequence to perform componentwise
1170 conversion. */
1173 complain);
1176 {
1179 }
1180 else
1184 }
1187 {
1191 }
1193 /* [conv.ptr]
1194 A null pointer constant can be converted to a pointer type; ... A
1195 null pointer constant of integral type can be converted to an
1196 rvalue of type std::nullptr_t. */
1204 {
1205 /* For backwards brain damage compatibility, allow interconversion of
1206 pointers and integers with a pedwarn. */
1209 }
1211 {
1212 /* For backwards brain damage compatibility, allow interconversion of
1213 enums and integers with a pedwarn. */
1216 }
1219 {
1220 tree to_pointee;
1221 tree from_pointee;
1224 {
1228 /* Since this is the target of a pointer, it can't have function
1229 qualifiers, so any TYPE_QUALS must be for attributes const or
1230 noreturn. Strip them. */
1237 }
1238 else
1239 {
1242 }
1246 to_pointee))
1247 ;
1251 {
1253 /* Don't try to apply restrict to void. */
1258 }
1260 {
1267 && (same_type_ignoring_top_level_qualifiers_p
1269 {
1272 }
1273 else
1275 }
1278 /* [conv.ptr]
1280 An rvalue of type "pointer to cv D," where D is a
1281 class type, can be converted to an rvalue of type
1282 "pointer to cv B," where B is a base class (clause
1283 _class.derived_) of D. If B is an inaccessible
1284 (clause _class.access_) or ambiguous
1285 (_class.member.lookup_) base class of D, a program
1286 that necessitates this conversion is ill-formed.
1287 Therefore, we use DERIVED_FROM_P, and do not check
1288 access or uniqueness. */
1290 {
1291 from_pointee
1297 }
1302 /* In a C-style cast, we ignore CV-qualification because we
1303 are allowed to perform a static_cast followed by a
1304 const_cast. */
1309 /* converting from string constant to char *. */
1313 /* Allow conversions among compatible ObjC pointer types (base
1314 conversions have been already handled above). */
1319 {
1322 }
1323 else
1327 }
1329 {
1343 else
1347 {
1349 tbase,
1355 }
1358 }
1360 {
1361 /* [conv.bool]
1363 A prvalue of arithmetic, unscoped enumeration, pointer, or pointer
1364 to member type can be converted to a prvalue of type bool. ...
1365 For direct-initialization (8.5 [dcl.init]), a prvalue of type
1366 std::nullptr_t can be converted to a prvalue of type bool; */
1372 {
1383 }
1386 }
1387 /* We don't check for ENUMERAL_TYPE here because there are no standard
1388 conversions to enum type. */
1389 /* As an extension, allow conversion to complex type. */
1391 {
1398 /* Give this a better rank if it's a promotion. */
1402 }
1408 {
1412 /* The derived-to-base conversion indicates the initialization
1413 of a parameter with base type from an object of a derived
1414 type. A temporary object is created to hold the result of
1415 the conversion unless we're binding directly to a reference. */
1417 }
1418 else
1425 }
1427 /* Returns nonzero if T1 is reference-related to T2. */
1429 bool
1431 {
1438 /* [dcl.init.ref]
1440 Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
1441 to "cv2 T2" if T1 is the same type as T2, or T1 is a base class
1442 of T2. */
1446 }
1448 /* Returns nonzero if T1 is reference-compatible with T2. */
1450 static bool
1452 {
1453 /* [dcl.init.ref]
1455 "cv1 T1" is reference compatible with "cv2 T2" if
1456 * T1 is reference-related to T2 or
1457 * T2 is "noexcept function" and T1 is "function", where the
1458 function types are otherwise the same,
1459 and cv1 is the same cv-qualification as, or greater cv-qualification
1460 than, cv2. */
1464 }
1466 /* A reference of the indicated TYPE is being bound directly to the
1467 expression represented by the implicit conversion sequence CONV.
1468 Return a conversion sequence for this binding. */
1472 {
1473 tree t;
1481 /* Mark the identity conv as to not decay to rvalue. */
1484 /* [over.ics.rank]
1486 When a parameter of reference type binds directly
1487 (_dcl.init.ref_) to an argument expression, the implicit
1488 conversion sequence is the identity conversion, unless the
1489 argument expression has a type that is a derived class of the
1490 parameter type, in which case the implicit conversion sequence is
1491 a derived-to-base Conversion.
1493 If the parameter binds directly to the result of applying a
1494 conversion function to the argument expression, the implicit
1495 conversion sequence is a user-defined conversion sequence
1496 (_over.ics.user_), with the second standard conversion sequence
1497 either an identity conversion or, if the conversion function
1498 returns an entity of a type that is a derived class of the
1499 parameter type, a derived-to-base conversion. */
1501 {
1502 /* Represent the derived-to-base conversion. */
1504 /* We will actually be binding to the base-class subobject in
1505 the derived class, so we mark this conversion appropriately.
1506 That way, convert_like knows not to generate a temporary. */
1508 }
1511 }
1513 /* Returns the conversion path from type FROM to reference type TO for
1514 purposes of reference binding. For lvalue binding, either pass a
1515 reference type to FROM or an lvalue expression to EXPR. If the
1516 reference will be bound to a temporary, NEED_TEMPORARY_P is set for
1517 the conversion returned. If C_CAST_P is true, this
1518 conversion is coming from a C-style cast. */
1522 tsubst_flags_t complain)
1523 {
1527 tree tfrom;
1530 cp_lvalue_kind gl_kind;
1534 {
1539 }
1542 {
1544 /* DR 1288: Otherwise, if the initializer list has a single element
1545 of type E and ... [T's] referenced type is reference-related to E,
1546 the object or reference is initialized from that element... */
1548 {
1554 {
1558 }
1559 }
1560 /* Otherwise, if T is a reference type, a prvalue temporary of the
1561 type referenced by T is copy-list-initialized or
1562 direct-list-initialized, depending on the kind of initialization
1563 for the reference, and the reference is bound to that temporary. */
1566 skip:;
1567 }
1570 {
1575 else
1577 }
1583 else
1586 /* Don't allow a class prvalue when LOOKUP_NO_TEMP_BIND. */
1591 /* Same mask as real_lvalue_p. */
1598 /* Figure out whether or not the types are reference-related and
1599 reference compatible. We have to do this after stripping
1600 references from FROM. */
1602 /* If this is a C cast, first convert to an appropriately qualified
1603 type, so that we can later do a const_cast to the desired type. */
1609 /* Directly bind reference when target expression's type is compatible with
1610 the reference and expression is an lvalue. In DR391, the wording in
1611 [8.5.3/5 dcl.init.ref] is changed to also require direct bindings for
1612 const and rvalue references to rvalues of compatible class type.
1613 We should also do direct bindings for non-class xvalues. */
1615 {
1616 /* [dcl.init.ref]
1618 If the initializer expression
1620 -- is an lvalue (but not an lvalue for a bit-field), and "cv1 T1"
1621 is reference-compatible with "cv2 T2,"
1623 the reference is bound directly to the initializer expression
1624 lvalue.
1626 [...]
1627 If the initializer expression is an rvalue, with T2 a class type,
1628 and "cv1 T1" is reference-compatible with "cv2 T2", the reference
1629 is bound to the object represented by the rvalue or to a sub-object
1630 within that object. */
1636 /* Handle rvalue reference to function properly. */
1637 conv->rvaluedness_matches_p
1639 else
1640 conv->rvaluedness_matches_p
1645 /* For the purposes of overload resolution, we ignore the fact
1646 this expression is a bitfield or packed field. (In particular,
1647 [over.ics.ref] says specifically that a function with a
1648 non-const reference parameter is viable even if the
1649 argument is a bitfield.)
1651 However, when we actually call the function we must create
1652 a temporary to which to bind the reference. If the
1653 reference is volatile, or isn't const, then we cannot make
1654 a temporary, so we just issue an error when the conversion
1655 actually occurs. */
1658 /* Don't allow binding of lvalues (other than function lvalues) to
1659 rvalue references. */
1664 /* Nor the reverse. */
1675 }
1676 /* [class.conv.fct] A conversion function is never used to convert a
1677 (possibly cv-qualified) object to the (possibly cv-qualified) same
1678 object type (or a reference to it), to a (possibly cv-qualified) base
1679 class of that type (or a reference to it).... */
1682 {
1683 /* [dcl.init.ref]
1685 If the initializer expression
1687 -- has a class type (i.e., T2 is a class type) can be
1688 implicitly converted to an lvalue of type "cv3 T3," where
1689 "cv1 T1" is reference-compatible with "cv3 T3". (this
1690 conversion is selected by enumerating the applicable
1691 conversion functions (_over.match.ref_) and choosing the
1692 best one through overload resolution. (_over.match_).
1694 the reference is bound to the lvalue result of the conversion
1695 in the second case. */
1697 complain);
1700 }
1702 /* From this point on, we conceptually need temporaries, even if we
1703 elide them. Only the cases above are "direct bindings". */
1707 /* [over.ics.rank]
1709 When a parameter of reference type is not bound directly to an
1710 argument expression, the conversion sequence is the one required
1711 to convert the argument expression to the underlying type of the
1712 reference according to _over.best.ics_. Conceptually, this
1713 conversion sequence corresponds to copy-initializing a temporary
1714 of the underlying type with the argument expression. Any
1715 difference in top-level cv-qualification is subsumed by the
1716 initialization itself and does not constitute a conversion. */
1718 /* [dcl.init.ref]
1720 Otherwise, the reference shall be an lvalue reference to a
1721 non-volatile const type, or the reference shall be an rvalue
1722 reference.
1724 We try below to treat this as a bad conversion to improve diagnostics,
1725 but if TO is an incomplete class, we need to reject this conversion
1726 now to avoid unnecessary instantiation. */
1731 /* We're generating a temporary now, but don't bind any more in the
1732 conversion (specifically, don't slice the temporary returned by a
1733 conversion operator). */
1736 /* Core issue 899: When [copy-]initializing a temporary to be bound
1737 to the first parameter of a copy constructor (12.8) called with
1738 a single argument in the context of direct-initialization,
1739 explicit conversion functions are also considered.
1741 So don't set LOOKUP_ONLYCONVERTING in that case. */
1752 {
1753 /* If initializing the temporary used a conversion function,
1754 recalculate the second conversion sequence. */
1758 {
1761 conversion *new_second
1767 }
1768 }
1771 /* This reference binding, unlike those above, requires the
1772 creation of a temporary. */
1776 /* [dcl.init.ref]
1778 Otherwise, the reference shall be an lvalue reference to a
1779 non-volatile const type, or the reference shall be an rvalue
1780 reference. */
1784 /* [dcl.init.ref]
1786 Otherwise, a temporary of type "cv1 T1" is created and
1787 initialized from the initializer expression using the rules for a
1788 non-reference copy initialization. If T1 is reference-related to
1789 T2, cv1 must be the same cv-qualification as, or greater
1790 cv-qualification than, cv2; otherwise, the program is ill-formed. */
1795 }
1797 /* Returns the implicit conversion sequence (see [over.ics]) from type
1798 FROM to type TO. The optional expression EXPR may affect the
1799 conversion. FLAGS are the usual overloading flags. If C_CAST_P is
1800 true, this conversion is coming from a C-style cast. */
1805 {
1812 /* Other flags only apply to the primary function in overload
1813 resolution, or after we've chosen one. */
1818 /* FIXME: actually we don't want warnings either, but we can't just
1819 have 'complain &= ~(tf_warning|tf_error)' because it would cause
1820 the regression of, eg, g++.old-deja/g++.benjamin/16077.C.
1821 We really ought not to issue that warning until we've committed
1822 to that conversion. */
1825 /* Call reshape_init early to remove redundant braces. */
1830 {
1835 }
1839 else
1846 {
1850 /* As an extension, allow list-initialization of _Complex. */
1852 {
1856 }
1858 /* Allow conversion from an initializer-list with one element to a
1859 scalar type. */
1861 {
1863 tree elt;
1869 else
1875 {
1878 /* Too many levels of braces, i.e. '{{1}}'. */
1881 }
1882 }
1885 }
1891 {
1901 {
1905 {
1906 /* "If C is not an initializer-list constructor and the
1907 initializer list has a single element of type cv U, where U is
1908 X or a class derived from X, the implicit conversion sequence
1909 has Exact Match rank if U is X, or Conversion rank if U is
1910 derived from X." */
1916 }
1918 }
1920 /* We used to try to bind a reference to a temporary here, but that
1921 is now handled after the recursive call to this function at the end
1922 of reference_binding. */
1924 }
1927 }
1929 /* Add a new entry to the list of candidates. Used by the add_*_candidate
1930 functions. ARGS will not be changed until a single candidate is
1931 selected. */
1940 {
1958 }
1960 /* Return the number of remaining arguments in the parameter list
1961 beginning with ARG. */
1963 int
1965 {
1970 n++;
1973 }
1975 /* Create an overload candidate for the function or method FN called
1976 with the argument list FIRST_ARG/ARGS and add it to CANDIDATES.
1977 FLAGS is passed on to implicit_conversion.
1979 This does not change ARGS.
1981 CTYPE, if non-NULL, is the type we want to pretend this function
1982 comes from for purposes of overload resolution. */
1989 tsubst_flags_t complain)
1990 {
1994 tree parmnode;
2000 /* At this point we should not see any functions which haven't been
2001 explicitly declared, except for friend functions which will have
2002 been found using argument dependent lookup. */
2005 /* The `this', `in_chrg' and VTT arguments to constructors are not
2006 considered in overload resolution. */
2008 {
2010 /* Bring back parameters omitted from an inherited ctor. */
2012 else
2016 {
2019 }
2020 }
2021 else
2027 /* 13.3.2 - Viable functions [over.match.viable]
2028 First, to be a viable function, a candidate function shall have enough
2029 parameters to agree in number with the arguments in the list.
2031 We need to check this first; otherwise, checking the ICSes might cause
2032 us to produce an ill-formed template instantiation. */
2036 {
2040 }
2044 {
2048 }
2050 /* An inherited constructor (12.6.3 [class.inhctor.init]) that has a first
2051 parameter of type "reference to cv C" (including such a constructor
2052 instantiated from a template) is excluded from the set of candidate
2053 functions when used to construct an object of type D with an argument list
2054 containing a single argument if C is reference-related to D. */
2056 && flag_new_inheriting_ctors
2058 {
2064 {
2067 }
2068 }
2070 /* Second, for a function to be viable, its constraints must be
2071 satisfied. */
2074 {
2077 }
2079 /* When looking for a function from a subobject from an implicit
2080 copy/move constructor/operator=, don't consider anything that takes (a
2081 reference to) an unrelated type. See c++/44909 and core 1092. */
2083 {
2089 else
2092 {
2095 ctype))
2097 }
2099 /* This only applies at the top level. */
2101 }
2106 /* Third, for F to be a viable function, there shall exist for each
2107 argument an implicit conversion sequence that converts that argument
2108 to the corresponding parameter of F. */
2113 {
2115 tree arg;
2124 else
2133 {
2139 /* The type of the implicit object parameter ('this') for
2140 overload resolution is not always the same as for the
2141 function itself; conversion functions are considered to
2142 be members of the class being converted, and functions
2143 introduced by a using-declaration are considered to be
2144 members of the class that uses them.
2146 Since build_over_call ignores the ICS for the `this'
2147 parameter, we can just change the parm type. */
2149 {
2150 parmtype = cp_build_qualified_type
2153 {
2154 /* If the function has a ref-qualifier, the implicit
2155 object parameter has reference type. */
2158 /* The special handling of 'this' conversions in compare_ics
2159 does not apply if there is a ref-qualifier. */
2161 }
2162 else
2163 {
2165 /* We don't use build_this here because we don't want to
2166 capture the object argument until we've chosen a
2167 non-static member function. */
2170 }
2171 }
2173 /* Core issue 899: When [copy-]initializing a temporary to be bound
2174 to the first parameter of a copy constructor (12.8) called with
2175 a single argument in the context of direct-initialization,
2176 explicit conversion functions are also considered.
2178 So set LOOKUP_COPY_PARM to let reference_binding know that
2179 it's being called in that context. We generalize the above
2180 to handle move constructors and template constructors as well;
2181 the standardese should soon be updated similarly. */
2185 && (same_type_ignoring_top_level_qualifiers_p
2187 {
2190 /* We allow user-defined conversions within init-lists, but
2191 don't list-initialize the copy parm, as that would mean
2192 using two levels of braces for the same type. */
2196 }
2197 else
2203 }
2204 else
2205 {
2209 }
2216 {
2220 }
2223 {
2226 }
2227 }
2229 out:
2232 }
2234 /* Create an overload candidate for the conversion function FN which will
2235 be invoked for expression OBJ, producing a pointer-to-function which
2236 will in turn be called with the argument list FIRST_ARG/ARGLIST,
2237 and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
2238 passed on to implicit_conversion.
2240 Actually, we don't really care about FN; we care about the type it
2241 converts to. There may be multiple conversion functions that will
2242 convert to that type, and we rely on build_user_type_conversion_1 to
2243 choose the best one; so when we create our candidate, we record the type
2244 instead of the function. */
2250 tsubst_flags_t complain)
2251 {
2269 /* Don't bother looking up the same type twice. */
2274 {
2280 else
2285 {
2288 /* Leave the 'cand' field null; we'll figure out the conversion in
2289 convert_like_real if this candidate is chosen. */
2291 }
2295 {
2299 }
2300 else
2301 {
2305 }
2312 {
2315 }
2322 }
2326 {
2330 }
2334 }
2336 static void
2340 {
2354 /* TRUTH_*_EXPR do "contextual conversion to bool", which means explicit
2355 conversion ops are allowed. We handle that here by just checking for
2356 boolean_type_node because other operators don't ask for it. COND_EXPR
2357 also does contextual conversion to bool for the first operand, but we
2358 handle that in build_conditional_expr, and type1 here is operand 2. */
2363 {
2370 {
2372 /* We need something for printing the candidate. */
2376 }
2378 {
2382 }
2384 }
2386 /* For COND_EXPR we rearranged the arguments; undo that now. */
2388 {
2393 complain);
2396 else
2397 {
2400 boolean_type_node);
2401 }
2402 }
2409 }
2411 static bool
2413 {
2415 }
2417 /* Returns nonzero if TYPE is a promoted arithmetic type. */
2419 static bool
2421 {
2422 /* [over.built]
2424 In this section, the term promoted integral type is used to refer
2425 to those integral types which are preserved by integral promotion
2426 (including e.g. int and long but excluding e.g. char).
2427 Similarly, the term promoted arithmetic type refers to promoted
2428 integral types plus floating types. */
2432 }
2434 /* Create any builtin operator overload candidates for the operator in
2435 question given the converted operand types TYPE1 and TYPE2. The other
2436 args are passed through from add_builtin_candidates to
2437 build_builtin_candidate.
2439 TYPE1 and TYPE2 may not be permissible, and we must filter them.
2440 If CODE is requires candidates operands of the same type of the kind
2441 of which TYPE1 and TYPE2 are, we add both candidates
2442 CODE (TYPE1, TYPE1) and CODE (TYPE2, TYPE2). */
2444 static void
2448 tsubst_flags_t complain)
2449 {
2451 {
2459 }
2462 {
2464 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2465 and VQ is either volatile or empty, there exist candidate operator
2466 functions of the form
2467 VQ T& operator++(VQ T&);
2468 T operator++(VQ T&, int);
2469 5 For every pair T, VQ), where T is an enumeration type or an arithmetic
2470 type other than bool, and VQ is either volatile or empty, there exist
2471 candidate operator functions of the form
2472 VQ T& operator--(VQ T&);
2473 T operator--(VQ T&, int);
2474 6 For every pair T, VQ), where T is a cv-qualified or cv-unqualified
2475 complete object type, and VQ is either volatile or empty, there exist
2476 candidate operator functions of the form
2477 T*VQ& operator++(T*VQ&);
2478 T*VQ& operator--(T*VQ&);
2479 T* operator++(T*VQ&, int);
2480 T* operator--(T*VQ&, int); */
2486 /* FALLTHRU */
2490 {
2493 }
2496 /* 7 For every cv-qualified or cv-unqualified object type T, there
2497 exist candidate operator functions of the form
2499 T& operator*(T*);
2501 8 For every function type T, there exist candidate operator functions of
2502 the form
2503 T& operator*(T*); */
2512 /* 9 For every type T, there exist candidate operator functions of the form
2513 T* operator+(T*);
2515 10For every promoted arithmetic type T, there exist candidate operator
2516 functions of the form
2517 T operator+(T);
2518 T operator-(T); */
2523 /* FALLTHRU */
2529 /* 11For every promoted integral type T, there exist candidate operator
2530 functions of the form
2531 T operator~(T); */
2538 /* 12For every quintuple C1, C2, T, CV1, CV2), where C2 is a class type, C1
2539 is the same type as C2 or is a derived class of C2, T is a complete
2540 object type or a function type, and CV1 and CV2 are cv-qualifier-seqs,
2541 there exist candidate operator functions of the form
2542 CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
2543 where CV12 is the union of CV1 and CV2. */
2547 {
2555 }
2558 /* 13For every pair of promoted arithmetic types L and R, there exist can-
2559 didate operator functions of the form
2560 LR operator*(L, R);
2561 LR operator/(L, R);
2562 LR operator+(L, R);
2563 LR operator-(L, R);
2564 bool operator<(L, R);
2565 bool operator>(L, R);
2566 bool operator<=(L, R);
2567 bool operator>=(L, R);
2568 bool operator==(L, R);
2569 bool operator!=(L, R);
2570 where LR is the result of the usual arithmetic conversions between
2571 types L and R.
2573 14For every pair of types T and I, where T is a cv-qualified or cv-
2574 unqualified complete object type and I is a promoted integral type,
2575 there exist candidate operator functions of the form
2576 T* operator+(T*, I);
2577 T& operator[](T*, I);
2578 T* operator-(T*, I);
2579 T* operator+(I, T*);
2580 T& operator[](I, T*);
2582 15For every T, where T is a pointer to complete object type, there exist
2583 candidate operator functions of the form112)
2584 ptrdiff_t operator-(T, T);
2586 16For every pointer or enumeration type T, there exist candidate operator
2587 functions of the form
2588 bool operator<(T, T);
2589 bool operator>(T, T);
2590 bool operator<=(T, T);
2591 bool operator>=(T, T);
2592 bool operator==(T, T);
2593 bool operator!=(T, T);
2595 17For every pointer to member type T, there exist candidate operator
2596 functions of the form
2597 bool operator==(T, T);
2598 bool operator!=(T, T); */
2605 {
2608 }
2609 /* FALLTHRU */
2622 {
2625 }
2627 {
2630 }
2631 /* Fall through. */
2647 {
2650 }
2653 {
2656 }
2662 /* FALLTHRU */
2665 {
2668 }
2670 {
2673 }
2676 /* 18For every pair of promoted integral types L and R, there exist candi-
2677 date operator functions of the form
2678 LR operator%(L, R);
2679 LR operator&(L, R);
2680 LR operator^(L, R);
2681 LR operator|(L, R);
2682 L operator<<(L, R);
2683 L operator>>(L, R);
2684 where LR is the result of the usual arithmetic conversions between
2685 types L and R. */
2693 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2697 /* 19For every triple L, VQ, R), where L is an arithmetic or enumeration
2698 type, VQ is either volatile or empty, and R is a promoted arithmetic
2699 type, there exist candidate operator functions of the form
2700 VQ L& operator=(VQ L&, R);
2701 VQ L& operator*=(VQ L&, R);
2702 VQ L& operator/=(VQ L&, R);
2703 VQ L& operator+=(VQ L&, R);
2704 VQ L& operator-=(VQ L&, R);
2706 20For every pair T, VQ), where T is any type and VQ is either volatile
2707 or empty, there exist candidate operator functions of the form
2708 T*VQ& operator=(T*VQ&, T*);
2710 21For every pair T, VQ), where T is a pointer to member type and VQ is
2711 either volatile or empty, there exist candidate operator functions of
2712 the form
2713 VQ T& operator=(VQ T&, T);
2715 22For every triple T, VQ, I), where T is a cv-qualified or cv-
2716 unqualified complete object type, VQ is either volatile or empty, and
2717 I is a promoted integral type, there exist candidate operator func-
2718 tions of the form
2719 T*VQ& operator+=(T*VQ&, I);
2720 T*VQ& operator-=(T*VQ&, I);
2722 23For every triple L, VQ, R), where L is an integral or enumeration
2723 type, VQ is either volatile or empty, and R is a promoted integral
2724 type, there exist candidate operator functions of the form
2726 VQ L& operator%=(VQ L&, R);
2727 VQ L& operator<<=(VQ L&, R);
2728 VQ L& operator>>=(VQ L&, R);
2729 VQ L& operator&=(VQ L&, R);
2730 VQ L& operator^=(VQ L&, R);
2731 VQ L& operator|=(VQ L&, R); */
2735 {
2739 {
2742 }
2743 /* FALLTHRU */
2756 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2769 {
2772 }
2777 }
2782 /* [over.built]
2784 For every pair of promoted arithmetic types L and R, there
2785 exist candidate operator functions of the form
2787 LR operator?(bool, L, R);
2789 where LR is the result of the usual arithmetic conversions
2790 between types L and R.
2792 For every type T, where T is a pointer or pointer-to-member
2793 type, there exist candidate operator functions of the form T
2794 operator?(bool, T, T); */
2798 /* That's OK. */
2801 /* Otherwise, the types should be pointers. */
2805 /* We don't check that the two types are the same; the logic
2806 below will actually create two candidates; one in which both
2807 parameter types are TYPE1, and one in which both parameter
2808 types are TYPE2. */
2819 }
2821 /* Make sure we don't create builtin candidates with dependent types. */
2825 {
2826 /* Try to recover if one of the types is non-dependent. But if
2827 there's only one type, there's nothing we can do. */
2830 /* And we lose if both are dependent. */
2833 /* Or if they have different forms. */
2841 }
2843 /* If we're dealing with two pointer types or two enumeral types,
2844 we need candidates for both of them. */
2853 {
2855 {
2857 error_mark_node,
2858 error_mark_node,
2859 CPO_CONVERSION,
2860 tf_none);
2862 {
2863 build_builtin_candidate
2867 }
2868 }
2870 build_builtin_candidate
2872 build_builtin_candidate
2875 }
2877 build_builtin_candidate
2879 }
2881 tree
2883 {
2889 }
2891 /* There are three conditions of builtin candidates:
2893 1) bool-taking candidates. These are the same regardless of the input.
2894 2) pointer-pair taking candidates. These are generated for each type
2895 one of the input types converts to.
2896 3) arithmetic candidates. According to the standard, we should generate
2897 all of these, but I'm trying not to...
2899 Here we generate a superset of the possible candidates for this particular
2900 case. That is a subset of the full set the standard defines, plus some
2901 other cases which the standard disallows. add_builtin_candidate will
2902 filter out the invalid set. */
2904 static void
2908 {
2912 /* TYPES[i] is the set of possible builtin-operator parameter types
2913 we will consider for the Ith argument. */
2918 {
2921 else
2923 }
2926 {
2927 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2928 and VQ is either volatile or empty, there exist candidate operator
2929 functions of the form
2930 VQ T& operator++(VQ T&); */
2940 /* 24There also exist candidate operator functions of the form
2941 bool operator!(bool);
2942 bool operator&&(bool, bool);
2943 bool operator||(bool, bool); */
2946 build_builtin_candidate
2953 build_builtin_candidate
2971 /* Fall through. */
2975 }
2981 {
2983 ;
2985 {
2986 tree convs;
2994 {
2999 }
3005 {
3018 {
3024 }
3028 }
3029 }
3030 else
3031 {
3036 {
3042 }
3044 }
3045 }
3047 /* Run through the possible parameter types of both arguments,
3048 creating candidates with those parameter types. */
3050 {
3052 tree u;
3056 add_builtin_candidate
3059 else
3060 add_builtin_candidate
3063 }
3067 }
3070 /* If TMPL can be successfully instantiated as indicated by
3071 EXPLICIT_TARGS and ARGLIST, adds the instantiation to CANDIDATES.
3073 TMPL is the template. EXPLICIT_TARGS are any explicit template
3074 arguments. ARGLIST is the arguments provided at the call-site.
3075 This does not change ARGLIST. The RETURN_TYPE is the desired type
3076 for conversion operators. If OBJ is NULL_TREE, FLAGS and CTYPE are
3077 as for add_function_candidate. If an OBJ is supplied, FLAGS and
3078 CTYPE are ignored, and OBJ is as for add_conv_candidate. */
3086 tsubst_flags_t complain)
3087 {
3097 tree arg;
3099 tree fn;
3103 /* We don't do deduction on the in-charge parameter, the VTT
3104 parameter or 'this'. */
3106 {
3110 /* We're deducing for a call to the result of a template conversion
3112 else
3114 }
3119 {
3122 else
3124 }
3132 {
3133 /* 12.8/6 says, "A declaration of a constructor for a class X is
3134 ill-formed if its first parameter is of type (optionally cv-qualified)
3135 X and either there are no other parameters or else all other
3136 parameters have default arguments. A member function template is never
3137 instantiated to produce such a constructor signature."
3139 So if we're trying to copy an object of the containing class, don't
3140 consider a template constructor that has a first parameter type that
3141 is just a template parameter, as we would deduce a signature that we
3142 would then reject in the code below. */
3144 {
3149 {
3153 }
3154 }
3155 }
3162 {
3165 }
3169 {
3172 }
3177 args_without_in_chrg,
3178 nargs_without_in_chrg,
3183 {
3184 /* Don't repeat unification later if it already resulted in errors. */
3188 nargs_without_in_chrg,
3190 else
3193 }
3196 {
3199 ctype))
3200 {
3201 /* We're trying to produce a constructor with a prohibited signature,
3202 as discussed above; handle here any cases we didn't catch then,
3203 such as X(X<T>). */
3206 }
3207 }
3210 /* Aha, this is a conversion function. */
3213 else
3218 /* This situation can occur if a member template of a template
3219 class is specialized. Then, instantiate_template might return
3220 an instantiation of the specialization, in which case the
3221 DECL_TI_TEMPLATE field will point at the original
3222 specialization. For example:
3224 template <class T> struct S { template <class U> void f(U);
3225 template <> void f(int) {}; };
3226 S<double> sd;
3227 sd.f(3);
3229 Here, TMPL will be template <class U> S<double>::f(U).
3230 And, instantiate template will give us the specialization
3231 template <> S<double>::f(int). But, the DECL_TI_TEMPLATE field
3232 for this will point at template <class T> template <> S<T>::f(int),
3233 so that we can find the definition. For the purposes of
3234 overload resolution, however, we want the original TMPL. */
3236 else
3241 fail:
3244 }
3253 {
3254 return
3259 }
3261 /* Create an overload candidate for the conversion function template TMPL,
3262 returning RETURN_TYPE, which will be invoked for expression OBJ to produce a
3263 pointer-to-function which will in turn be called with the argument list
3264 ARGLIST, and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
3265 passed on to implicit_conversion. */
3269 tree obj,
3273 {
3274 /* Making this work broke PR 71117, so until the committee resolves core
3275 issue 2189, let's disable this candidate if there are any viable call
3276 operators. */
3280 return
3284 complain);
3285 }
3287 /* The CANDS are the set of candidates that were considered for
3288 overload resolution. Return the set of viable candidates, or CANDS
3289 if none are viable. If any of the candidates were viable, set
3290 *ANY_VIABLE_P to true. STRICT_P is true if a candidate should be
3291 considered viable only if it is strictly viable. */
3297 {
3303 /* Be strict inside templates, since build_over_call won't actually
3304 do the conversions to get pedwarns. */
3314 {
3318 {
3319 /* Be strict in the presence of a viable candidate. Also if
3320 there are template candidates, so that we get deduction errors
3321 for them instead of silently preferring a bad conversion. */
3324 {
3325 /* Put any spliced near matches back onto the main list so
3326 that we see them if there is no strict match. */
3332 }
3333 }
3336 {
3344 }
3345 else
3347 }
3350 }
3352 static bool
3354 {
3359 }
3361 /* OBJ is being used in an expression like "OBJ.f (...)". In other
3362 words, it is about to become the "this" pointer for a member
3363 function call. Take the address of the object. */
3365 static tree
3367 {
3368 /* In a template, we are only concerned about the type of the
3369 expression, so we can take a shortcut. */
3374 }
3376 /* Returns true iff functions are equivalent. Equivalent functions are
3377 not '==' only if one is a function-local extern function or if
3378 both are extern "C". */
3382 {
3391 }
3393 /* Print information about a candidate being rejected due to INFO. */
3395 static void
3397 {
3402 {
3403 /* Conversion of implicit `this' argument failed. */
3405 /* A bad conversion for 'this' must be discarding cv-quals. */
3408 from);
3409 else
3413 }
3415 {
3420 tf_warning_or_error);
3421 }
3423 /* Conversion of conversion function return value failed. */
3426 else
3429 }
3431 /* Print information about a candidate with WANT parameters and we found
3432 HAVE. */
3434 static void
3436 {
3441 }
3443 /* Print information about one overload candidate CANDIDATE. MSGSTR
3444 is the text to print before the candidate itself.
3446 NOTE: Unlike most diagnostic functions in GCC, MSGSTR is expected
3447 to have been run through gettext by the caller. This wart makes
3448 life simpler in print_z_candidates and for the translators. */
3450 static void
3453 {
3463 {
3474 else
3477 }
3484 else
3487 {
3490 }
3491 /* Give the user some information about why this candidate failed. */
3493 {
3497 {
3510 "cannot be converted to %qT with a qualification "
3516 "conversion function specialization to %qT is not an "
3521 /* We use template_unification_error_rejection if unification caused
3522 actual non-SFINAE errors, in which case we don't need to repeat
3523 them here. */
3525 {
3529 }
3530 /* Re-run template unification with diagnostics. */
3534 (make_tree_vec
3545 " a constructor taking a single argument of its own "
3549 {
3553 }
3557 "initialization from an expression of the same or derived "
3562 /* This candidate didn't have any issues or we failed to
3563 handle a particular code. Either way... */
3565 }
3566 }
3567 }
3569 static void
3571 {
3578 /* Remove non-viable deleted candidates. */
3581 {
3586 else
3588 }
3589 /* ...if there are any non-deleted ones. */
3593 /* There may be duplicates in the set of candidates. We put off
3594 checking this condition as long as possible, since we have no way
3595 to eliminate duplicates from a set of functions in less than n^2
3596 time. Now we are about to emit an error message, so it is more
3597 permissible to go slowly. */
3599 {
3601 /* Skip builtin candidates and conversion functions. */
3606 {
3610 else
3612 }
3613 }
3617 }
3619 /* USER_SEQ is a user-defined conversion sequence, beginning with a
3620 USER_CONV. STD_SEQ is the standard conversion sequence applied to
3621 the result of the conversion function to convert it to the final
3622 desired type. Merge the two sequences into a single sequence,
3623 and return the merged sequence. */
3627 {
3633 /* Find the end of the second conversion sequence. */
3635 {
3636 /* The entire sequence is a user-conversion sequence. */
3640 }
3642 /* Replace the identity conversion with the user conversion
3643 sequence. */
3647 }
3649 /* Handle overload resolution for initializing an object of class type from
3650 an initializer list. First we look for a suitable constructor that
3651 takes a std::initializer_list; if we don't find one, we then look for a
3652 non-list constructor.
3654 Parameters are as for add_candidates, except that the arguments are in
3655 the form of a CONSTRUCTOR (the initializer list) rather than a vector, and
3656 the RETURN_TYPE parameter is replaced by TOTYPE, the desired type. */
3658 static void
3665 tsubst_flags_t complain)
3666 {
3669 /* We're looking for a ctor for list-initialization. */
3671 /* And we don't allow narrowing conversions. We also use this flag to
3672 avoid the copy constructor call for copy-list-initialization. */
3678 /* Always use the default constructor if the list is empty (DR 990). */
3681 ;
3682 /* If the class has a list ctor, try passing the list as a single
3683 argument first, but only consider list ctors. */
3685 {
3692 }
3694 /* Expand the CONSTRUCTOR into a new argument vec. */
3702 /* We aren't looking for list-ctors anymore. */
3704 /* We allow more user-defined conversions within an init-list. */
3710 }
3712 /* Returns the best overload candidate to perform the requested
3713 conversion. This function is used for three the overloading situations
3714 described in [over.match.copy], [over.match.conv], and [over.match.ref].
3715 If TOTYPE is a REFERENCE_TYPE, we're trying to find a direct binding as
3716 per [dcl.init.ref], so we ignore temporary bindings. */
3720 tsubst_flags_t complain)
3721 {
3723 tree fromtype;
3737 /* We represent conversion within a hierarchy using RVALUE_CONV and
3738 BASE_CONV, as specified by [over.best.ics]; these become plain
3739 constructor calls, as specified in [dcl.init]. */
3744 /* Use lookup_fnfields_slot instead of lookup_fnfields to avoid
3745 creating a garbage BASELINK; constructors can't be inherited. */
3748 /* FIXME P0135 doesn't say what to do in C++17 about list-initialization from
3749 a single element. For now, let's handle constructors as before and also
3750 consider conversion operators from the element. */
3757 {
3762 {
3763 /* [class.conv.fct] A conversion function is never used to
3764 convert a (possibly cv-qualified) object to the (possibly
3765 cv-qualified) same object type (or a reference to it), to a
3766 (possibly cv-qualified) base class of that type (or a
3767 reference to it)... */
3768 }
3769 else
3771 }
3778 /* It's OK to bind a temporary for converting constructor arguments, but
3779 not in converting the return value of a conversion operator. */
3785 {
3790 /* We should never try to call the abstract or base constructor
3791 from here. */
3797 {
3798 /* List-initialization. */
3802 }
3803 else
3804 {
3808 }
3811 {
3814 /* If totype isn't a reference, and LOOKUP_NO_TEMP_BIND isn't
3815 set, then this is copy-initialization. In that case, "The
3816 result of the call is then used to direct-initialize the
3817 object that is the destination of the copy-initialization."
3818 [dcl.init]
3820 We represent this in the conversion sequence with an
3821 rvalue conversion, which means a constructor call. */
3824 cand->second_conv
3826 }
3827 }
3830 {
3832 /* FIXME see above about C++17. */
3834 else
3836 }
3839 {
3843 /* If we are called to convert to a reference type, we are trying to
3844 find a direct binding, so don't even consider temporaries. If
3845 we don't find a direct binding, the caller will try again to
3846 look for a temporary binding. */
3857 {
3859 conversion *ics
3861 rettype,
3864 complain);
3866 /* If LOOKUP_NO_TEMP_BIND isn't set, then this is
3867 copy-initialization. In that case, "The result of the
3868 call is then used to direct-initialize the object that is
3869 the destination of the copy-initialization." [dcl.init]
3871 We represent this in the conversion sequence with an
3872 rvalue conversion, which means a constructor call. But
3873 don't add a second rvalue conversion if there's already
3874 one there. Which there really shouldn't be, but it's
3875 harmless since we'd add it here anyway. */
3883 {
3887 }
3890 {
3891 /* 13.3.1.5: For direct-initialization, those explicit
3892 conversion functions that are not hidden within S and
3893 yield type T or a type that can be converted to type T
3894 with a qualification conversion (4.4) are also candidate
3895 functions. */
3896 /* 13.3.1.6 doesn't have a parallel restriction, but it should;
3897 I've raised this issue with the committee. --jason 9/2011 */
3900 }
3902 {
3904 cand->reason
3907 }
3910 {
3911 /* 13.3.3.1.2: If the user-defined conversion is specified by
3912 a specialization of a conversion function template, the
3913 second standard conversion sequence shall have exact match
3914 rank. */
3917 }
3918 }
3919 }
3923 {
3927 }
3931 {
3933 {
3937 }
3944 /* If there are viable candidates, don't set ICS_BAD_FLAG; an
3945 ambiguous conversion is no worse than another user-defined
3946 conversion. */
3949 }
3951 tree convtype;
3955 /* DR 5: [in the first step of copy-initialization]...if the function
3956 is a constructor, the call initializes a temporary of the
3957 cv-unqualified version of the destination type. */
3959 else
3961 /* Build the user conversion sequence. */
3962 conv = build_conv
3964 convtype,
3970 /* Remember that this was a list-initialization. */
3974 /* Combine it with the second conversion sequence. */
3979 }
3981 /* Wrapper for above. */
3983 tree
3985 tsubst_flags_t complain)
3986 {
3988 tree ret;
3994 {
3997 else
3998 {
4001 }
4002 }
4003 else
4008 }
4010 /* Subroutine of convert_nontype_argument.
4012 EXPR is an expression used in a context that requires a converted
4013 constant-expression, such as a template non-type parameter. Do any
4014 necessary conversions (that are permitted for converted
4015 constant-expressions) to convert it to the desired type.
4017 If conversion is successful, returns the converted expression;
4018 otherwise, returns error_mark_node. */
4020 tree
4022 {
4025 tree t;
4031 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4038 /* A converted constant expression of type T is an expression, implicitly
4039 converted to type T, where the converted expression is a constant
4040 expression and the implicit conversion sequence contains only
4042 * user-defined conversions,
4043 * lvalue-to-rvalue conversions (7.1),
4044 * array-to-pointer conversions (7.2),
4045 * function-to-pointer conversions (7.3),
4046 * qualification conversions (7.5),
4047 * integral promotions (7.6),
4048 * integral conversions (7.8) other than narrowing conversions (11.6.4),
4049 * null pointer conversions (7.11) from std::nullptr_t,
4050 * null member pointer conversions (7.12) from std::nullptr_t, and
4051 * function pointer conversions (7.13),
4053 and where the reference binding (if any) binds directly. */
4058 {
4060 {
4061 /* A conversion function is OK. If it isn't constexpr, we'll
4062 complain later that the argument isn't constant. */
4064 /* The lvalue-to-rvalue conversion is OK. */
4066 /* Array-to-pointer and function-to-pointer. */
4068 /* Function pointer conversions. */
4070 /* Qualification conversions. */
4076 {
4082 }
4092 /* Integral promotion or conversion. */
4095 /* Conversion from nullptr to pointer or pointer-to-member. */
4101 /* fall through. */
4106 }
4107 }
4109 /* Avoid confusing convert_nontype_argument by introducing
4110 a redundant conversion to the same reference type. */
4113 {
4117 }
4121 else
4124 /* Free all the conversions we allocated. */
4128 }
4130 /* Do any initial processing on the arguments to a function call. */
4134 {
4136 tree arg;
4139 {
4143 {
4147 }
4150 }
4152 }
4154 /* Perform overload resolution on FN, which is called with the ARGS.
4156 Return the candidate function selected by overload resolution, or
4157 NULL if the event that overload resolution failed. In the case
4158 that overload resolution fails, *CANDIDATES will be the set of
4159 candidates considered, and ANY_VIABLE_P will be set to true or
4160 false to indicate whether or not any of the candidates were
4161 viable.
4163 The ARGS should already have gone through RESOLVE_ARGS before this
4164 function is called. */
4171 {
4173 tree explicit_targs;
4184 /* Check FN. */
4191 {
4195 }
4197 /* Add the various candidate functions. */
4202 LOOKUP_NORMAL,
4208 else
4213 }
4215 /* Print an error message about being unable to build a call to FN with
4216 ARGS. ANY_VIABLE_P indicates whether any candidate functions could
4217 be located; CANDIDATES is a possibly empty list of such
4218 functions. */
4220 static void
4223 {
4226 {
4229 }
4238 else
4243 }
4245 /* Return an expression for a call to FN (a namespace-scope function,
4246 or a static member function) with the ARGS. This may change
4247 ARGS. */
4249 tree
4251 tsubst_flags_t complain)
4252 {
4256 tree result;
4259 {
4263 }
4268 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4272 complain);
4275 {
4277 {
4278 // If there is a single (non-viable) function candidate,
4279 // let the error be diagnosed by cp_build_function_call_vec.
4284 // Otherwise, emit notes for non-viable candidates.
4286 }
4288 }
4289 else
4290 {
4292 /* If fn is template_id_expr, the call has explicit template arguments
4293 (e.g. func<int>(5)), communicate this info to build_over_call
4294 through flags so that later we can use it to decide whether to warn
4295 about peculiar null pointer conversion. */
4297 {
4298 /* If overload resolution selects a specialization of a
4299 function concept for non-dependent template arguments,
4300 the expression is true if the constraints are satisfied
4301 and false otherwise.
4303 NOTE: This is an extension of Concepts Lite TS that
4304 allows constraints to be used in expressions. */
4306 {
4312 }
4315 }
4318 }
4320 /* Free all the conversions we allocated. */
4324 }
4326 /* Build a call to a global operator new. FNNAME is the name of the
4327 operator (either "operator new" or "operator new[]") and ARGS are
4328 the arguments provided. This may change ARGS. *SIZE points to the
4329 total number of bytes required by the allocation, and is updated if
4330 that is changed here. *COOKIE_SIZE is non-NULL if a cookie should
4331 be used. If this function determines that no cookie should be
4332 used, after all, *COOKIE_SIZE is set to NULL_TREE. If SIZE_CHECK
4333 is not NULL_TREE, it is evaluated before calculating the final
4334 array size, and if it fails, the array size is replaced with
4335 (size_t)-1 (usually triggering a std::bad_alloc exception). If FN
4336 is non-NULL, it will be set, upon return, to the allocation
4337 function called. */
4339 tree
4344 {
4346 tree fns;
4353 /* Set to (size_t)-1 if the size check fails. */
4355 {
4361 }
4367 /* Based on:
4369 [expr.new]
4371 If this lookup fails to find the name, or if the allocated type
4372 is not a class type, the allocation function's name is looked
4373 up in the global scope.
4375 we disregard block-scope declarations of "operator new". */
4380 {
4387 /* If no aligned allocation function matches, try again without the
4388 alignment. */
4389 }
4391 /* Figure out what function is being called. */
4394 complain);
4396 /* If no suitable function could be found, issue an error message
4397 and give up. */
4399 {
4403 }
4405 /* If a cookie is required, add some extra space. Whether
4406 or not a cookie is required cannot be determined until
4407 after we know which function was called. */
4409 {
4411 tree arg_types;
4414 /* Skip the size_t parameter. */
4416 /* Check the remaining parameters (if any). */
4420 ptr_type_node))
4422 /* If we need a cookie, adjust the number of bytes allocated. */
4424 {
4425 /* Update the total size. */
4428 {
4429 /* Set to (size_t)-1 if the size check fails. */
4433 }
4434 /* Update the argument list to reflect the adjusted size. */
4436 }
4437 else
4439 }
4441 /* Tell our caller which function we decided to call. */
4445 /* Build the CALL_EXPR. */
4447 }
4449 /* Build a new call to operator(). This may change ARGS. */
4451 static tree
4453 {
4470 {
4472 /* It's no good looking for an overloaded operator() on a
4473 pointer-to-member-function. */
4477 }
4480 {
4484 }
4485 else
4489 {
4493 }
4495 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4499 {
4507 }
4512 {
4520 {
4527 add_template_conv_candidate
4531 else
4535 }
4536 }
4538 /* Be strict here because if we choose a bad conversion candidate, the
4539 errors we get won't mention the call context. */
4542 {
4544 {
4548 }
4550 }
4551 else
4552 {
4555 {
4557 {
4561 }
4563 }
4568 else
4569 {
4573 else
4574 {
4577 }
4580 }
4581 }
4583 /* Free all the conversions we allocated. */
4587 }
4589 /* Wrapper for above. */
4591 tree
4593 {
4594 tree ret;
4599 }
4601 /* Called by op_error to prepare format strings suitable for the error
4602 function. It concatenates a prefix (controlled by MATCH), ERRMSG,
4603 and a suffix (controlled by NTYPES). */
4607 {
4617 else
4621 }
4623 static void
4626 {
4631 {
4637 else
4649 else
4659 else
4670 else
4680 else
4685 else
4689 else
4694 }
4695 }
4697 /* Return the implicit conversion sequence that could be used to
4698 convert E1 to E2 in [expr.cond]. */
4702 {
4708 /* [expr.cond]
4710 If E2 is an lvalue: E1 can be converted to match E2 if E1 can be
4711 implicitly converted (clause _conv_) to the type "lvalue reference to
4712 T2", subject to the constraint that in the conversion the
4713 reference must bind directly (_dcl.init.ref_) to an lvalue.
4715 If E2 is an xvalue: E1 can be converted to match E2 if E1 can be
4716 implicitly converted to the type "rvalue reference to T2", subject to
4717 the constraint that the reference must bind directly. */
4719 {
4722 t1,
4723 e1,
4725 LOOKUP_NO_TEMP_BIND|LOOKUP_NO_RVAL_BIND
4727 complain);
4730 }
4732 /* If E2 is a prvalue or if neither of the conversions above can be done
4733 and at least one of the operands has (possibly cv-qualified) class
4734 type: */
4738 /* [expr.cond]
4740 If E1 and E2 have class type, and the underlying class types are
4741 the same or one is a base class of the other: E1 can be converted
4742 to match E2 if the class of T2 is the same type as, or a base
4743 class of, the class of T1, and the cv-qualification of T2 is the
4744 same cv-qualification as, or a greater cv-qualification than, the
4745 cv-qualification of T1. If the conversion is applied, E1 is
4746 changed to an rvalue of type T2 that still refers to the original
4747 source class object (or the appropriate subobject thereof). */
4750 {
4752 {
4757 else
4760 }
4761 else
4763 }
4764 else
4765 /* [expr.cond]
4767 Otherwise: E1 can be converted to match E2 if E1 can be implicitly
4768 converted to the type that expression E2 would have if E2 were
4769 converted to an rvalue (or the type it has, if E2 is an rvalue). */
4772 }
4774 /* Implement [expr.cond]. ARG1, ARG2, and ARG3 are the three
4775 arguments to the conditional expression. */
4777 static tree
4779 tsubst_flags_t complain)
4780 {
4781 tree arg2_type;
4782 tree arg3_type;
4791 /* As a G++ extension, the second argument to the conditional can be
4792 omitted. (So that `a ? : c' is roughly equivalent to `a ? a :
4793 c'.) If the second operand is omitted, make sure it is
4794 calculated only once. */
4796 {
4804 /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */
4807 else
4809 }
4811 /* If something has already gone wrong, just pass that fact up the
4812 tree. */
4822 {
4825 /* If arg1 is another cond_expr choosing between -1 and 0,
4826 then we can use its comparison. It may help to avoid
4827 additional comparison, produce more accurate diagnostics
4828 and enables folding. */
4838 /* force_rvalue can return error_mark on valid arguments. */
4849 {
4850 /* Rely on the error messages of the scalar version. */
4859 {
4867 }
4871 /* We could pass complain & tf_warning to unsafe_conversion_p,
4872 but the warnings (like Wsign-conversion) have already been
4873 given by the scalar build_conditional_expr_1. We still check
4874 unsafe_conversion_p to forbid truncating long long -> float. */
4876 {
4881 }
4883 {
4888 }
4898 }
4901 {
4907 {
4911 {
4917 }
4919 {
4925 }
4928 }
4929 }
4935 {
4938 "incompatible vector types in conditional expression: "
4942 }
4945 {
4948 }
4950 }
4952 /* [expr.cond]
4954 The first expression is implicitly converted to bool (clause
4955 _conv_). */
4957 LOOKUP_NORMAL);
4961 /* [expr.cond]
4963 If either the second or the third operand has type (possibly
4964 cv-qualified) void, then the lvalue-to-rvalue (_conv.lval_),
4965 array-to-pointer (_conv.array_), and function-to-pointer
4966 (_conv.func_) standard conversions are performed on the second
4967 and third operands. */
4971 {
4972 /* Do the conversions. We don't these for `void' type arguments
4973 since it can't have any effect and since decay_conversion
4974 does not handle that case gracefully. */
4982 /* [expr.cond]
4984 One of the following shall hold:
4986 --The second or the third operand (but not both) is a
4987 throw-expression (_except.throw_); the result is of the
4988 type of the other and is an rvalue.
4990 --Both the second and the third operands have type void; the
4991 result is of type void and is an rvalue.
4993 We must avoid calling force_rvalue for expressions of type
4994 "void" because it will complain that their value is being
4995 used. */
4998 {
5000 {
5004 }
5007 }
5010 {
5012 {
5016 }
5019 }
5022 else
5023 {
5025 {
5028 "second operand to the conditional operator "
5029 "is of type %<void%>, but the third operand is "
5031 else
5033 "third operand to the conditional operator "
5034 "is of type %<void%>, but the second operand is "
5036 }
5038 }
5042 }
5043 /* [expr.cond]
5045 Otherwise, if the second and third operand have different types,
5046 and either has (possibly cv-qualified) class type, or if both are
5047 glvalues of the same value category and the same type except for
5048 cv-qualification, an attempt is made to convert each of those operands
5049 to the type of the other. */
5053 arg3_type)
5056 {
5061 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5067 /* [expr.cond]
5069 If both can be converted, or one can be converted but the
5070 conversion is ambiguous, the program is ill-formed. If
5071 neither can be converted, the operands are left unchanged and
5072 further checking is performed as described below. If exactly
5073 one conversion is possible, that conversion is applied to the
5074 chosen operand and the converted operand is used in place of
5075 the original operand for the remainder of this section. */
5080 {
5082 {
5089 else
5091 }
5093 }
5095 {
5099 /* Even if CONV2 is a valid conversion, the result of the
5100 conversion may be invalid. For example, if ARG3 has type
5101 "volatile X", and X does not have a copy constructor
5102 accepting a "volatile X&", then even if ARG2 can be
5103 converted to X, the conversion will fail. */
5107 }
5109 {
5116 }
5118 /* Free all the conversions we allocated. */
5124 /* If, after the conversion, both operands have class type,
5125 treat the cv-qualification of both operands as if it were the
5126 union of the cv-qualification of the operands.
5128 The standard is not clear about what to do in this
5129 circumstance. For example, if the first operand has type
5130 "const X" and the second operand has a user-defined
5131 conversion to "volatile X", what is the type of the second
5132 operand after this step? Making it be "const X" (matching
5133 the first operand) seems wrong, as that discards the
5134 qualification without actually performing a copy. Leaving it
5135 as "volatile X" seems wrong as that will result in the
5136 conditional expression failing altogether, even though,
5137 according to this step, the one operand could be converted to
5138 the type of the other. */
5146 }
5148 /* [expr.cond]
5150 If the second and third operands are glvalues of the same value
5151 category and have the same type, the result is of that type and
5152 value category. */
5156 {
5159 /* Let lvalue_kind know this was a glvalue. */
5165 }
5167 /* [expr.cond]
5169 Otherwise, the result is an rvalue. If the second and third
5170 operand do not have the same type, and either has (possibly
5171 cv-qualified) class type, overload resolution is used to
5172 determine the conversions (if any) to be applied to the operands
5173 (_over.match.oper_, _over.built_). */
5177 {
5182 /* Rearrange the arguments so that add_builtin_candidate only has
5183 to know about two args. In build_builtin_candidate, the
5184 arguments are unscrambled. */
5189 COND_EXPR,
5190 NOP_EXPR,
5192 args,
5195 /* [expr.cond]
5197 If the overload resolution fails, the program is
5198 ill-formed. */
5201 {
5206 }
5209 {
5211 {
5214 }
5216 }
5218 /* [expr.cond]
5220 Otherwise, the conversions thus determined are applied, and
5221 the converted operands are used in place of the original
5222 operands for the remainder of this section. */
5231 }
5233 /* [expr.cond]
5235 Lvalue-to-rvalue (_conv.lval_), array-to-pointer (_conv.array_),
5236 and function-to-pointer (_conv.func_) standard conversions are
5237 performed on the second and third operands.
5239 We need to force the lvalue-to-rvalue conversion here for class types,
5240 so we get TARGET_EXPRs; trying to deal with a COND_EXPR of class rvalues
5241 that isn't wrapped with a TARGET_EXPR plays havoc with exception
5242 regions. */
5255 /* [expr.cond]
5257 After those conversions, one of the following shall hold:
5259 --The second and third operands have the same type; the result is of
5260 that type. */
5263 /* [expr.cond]
5265 --The second and third operands have arithmetic or enumeration
5266 type; the usual arithmetic conversions are performed to bring
5267 them to a common type, and the result is of that type. */
5272 {
5273 /* In this case, there is always a common type. */
5275 arg3_type);
5278 "implicit conversion from %qH to %qI to "
5280 loc);
5284 {
5288 /* Two enumerators from the same enumeration can have different
5294 }
5301 {
5305 }
5309 }
5310 /* [expr.cond]
5312 --The second and third operands have pointer type, or one has
5313 pointer type and the other is a null pointer constant; pointer
5314 conversions (_conv.ptr_) and qualification conversions
5315 (_conv.qual_) are performed to bring them to their composite
5316 pointer type (_expr.rel_). The result is of the composite
5317 pointer type.
5319 --The second and third operands have pointer to member type, or
5320 one has pointer to member type and the other is a null pointer
5321 constant; pointer to member conversions (_conv.mem_) and
5322 qualification conversions (_conv.qual_) are performed to bring
5323 them to a common type, whose cv-qualification shall match the
5324 cv-qualification of either the second or the third operand.
5325 The result is of the common type. */
5333 {
5336 complain);
5341 }
5344 {
5349 }
5354 valid_operands:
5357 /* If the ARG2 and ARG3 are the same and don't have side-effects,
5358 warn here, because the COND_EXPR will be turned into ARG2. */
5365 /* We can't use result_type below, as fold might have returned a
5366 throw_expr. */
5369 {
5370 /* Expand both sides into the same slot, hopefully the target of
5371 the ?: expression. We used to check for TARGET_EXPRs here,
5372 but now we sometimes wrap them in NOP_EXPRs so the test would
5373 fail. */
5376 /* If this expression is an rvalue, but might be mistaken for an
5377 lvalue, we must add a NON_LVALUE_EXPR. */
5379 }
5380 else
5384 }
5386 /* Wrapper for above. */
5388 tree
5390 tsubst_flags_t complain)
5391 {
5392 tree ret;
5397 }
5399 /* OPERAND is an operand to an expression. Perform necessary steps
5400 required before using it. If OPERAND is NULL_TREE, NULL_TREE is
5401 returned. */
5403 static tree
5405 {
5407 {
5410 /* Make sure the template type is instantiated now. */
5412 }
5415 }
5417 /* Add each of the viable functions in FNS (a FUNCTION_DECL or
5418 OVERLOAD) to the CANDIDATES, returning an updated list of
5419 CANDIDATES. The ARGS are the arguments provided to the call;
5420 if FIRST_ARG is non-null it is the implicit object argument,
5421 otherwise the first element of ARGS is used if needed. The
5422 EXPLICIT_TARGS are explicit template arguments provided.
5423 TEMPLATE_ONLY is true if only template functions should be
5424 considered. CONVERSION_PATH, ACCESS_PATH, and FLAGS are as for
5425 add_function_candidate. */
5427 static void
5429 tree return_type,
5434 tsubst_flags_t complain)
5435 {
5436 tree ctype;
5440 unification_kind_t strict;
5445 /* Precalculate special handling of constructors and conversion ops. */
5448 {
5452 /* We're doing return_type(x). */
5454 else
5455 /* We're doing x.operator return_type(). */
5457 /* [over.match.funcs] For conversion functions, the function
5458 is considered to be a member of the class of the implicit
5459 object argument for the purpose of defining the type of
5460 the implicit object parameter. */
5462 }
5463 else
5464 {
5466 {
5468 /* For list-initialization we consider explicit constructors
5469 and complain if one is chosen. */
5470 check_converting
5473 }
5476 }
5480 else
5481 /* Delay creating the implicit this parameter until it is needed. */
5485 {
5497 {
5498 /* Figure out where the object arg comes from. If this
5499 function is a non-static member and we didn't get an
5500 implicit object argument, move it out of args. */
5502 {
5504 tree arg;
5511 }
5515 }
5519 fn,
5520 ctype,
5521 explicit_targs,
5522 fn_first_arg,
5523 fn_args,
5524 return_type,
5525 access_path,
5526 conversion_path,
5527 flags,
5528 strict,
5529 complain);
5532 fn,
5533 ctype,
5534 fn_first_arg,
5535 fn_args,
5536 access_path,
5537 conversion_path,
5538 flags,
5539 complain);
5540 }
5541 }
5543 /* Returns 1 if P0145R2 says that the LHS of operator CODE is evaluated first,
5544 -1 if the RHS is evaluated first, or 0 if the order is unspecified. */
5546 static int
5548 {
5550 {
5551 // 5. b @= a
5555 // 6. a[b]
5559 // 1. a.b
5560 // Not overloadable (yet).
5561 // 2. a->b
5562 // Only one argument.
5563 // 3. a->*b
5565 // 7. a << b
5567 // 8. a >> b
5573 }
5574 }
5576 static tree
5579 {
5600 {
5603 }
5610 {
5615 /* Use build_op_new_call and build_op_delete_call instead. */
5619 /* Use build_op_call instead. */
5626 /* These are saved for the sake of warn_logical_operator. */
5636 /* These are saved for the sake of maybe_warn_bool_compare. */
5641 /* =, ->, [], () must be non-static member functions. */
5645 /* FALLTHRU */
5653 }
5659 /* Use build_conditional_expr instead. */
5675 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5678 /* Add namespace-scope operators to the list of functions to
5679 consider. */
5681 {
5687 }
5693 /* Add class-member operators to the candidate set. */
5695 {
5696 tree fns;
5700 {
5703 }
5711 }
5712 /* Per 13.3.1.2/3, 2nd bullet, if no operand has a class type, then
5713 only non-member functions that have type T1 or reference to
5714 cv-qualified-opt T1 for the first argument, if the first argument
5715 has an enumeration type, or T2 or reference to cv-qualified-opt
5716 T2 for the second argument, if the second argument has an
5717 enumeration type. Filter out those that don't match. */
5719 {
5723 {
5733 {
5739 && (same_type_ignoring_top_level_qualifiers_p
5744 }
5746 /* No argument has an appropriate type, so remove this
5747 candidate function from the list. */
5749 {
5752 }
5753 }
5754 }
5760 {
5763 /* For these, the built-in candidates set is empty
5764 [over.match.oper]/3. We don't want non-strict matches
5765 because exact matches are always possible with built-in
5766 operators. The built-in candidate set for COMPONENT_REF
5767 would be empty too, but since there are no such built-in
5768 operators, we accept non-strict matches for them. */
5775 }
5779 {
5781 {
5784 /* Don't try anything fancy if we're not allowed to produce
5785 errors. */
5789 /* Look for an `operator++ (int)'. Pre-1985 C++ didn't
5790 distinguish between prefix and postfix ++ and
5791 operator++() was used for both, so we allow this with
5792 -fpermissive. */
5793 else
5794 {
5800 }
5807 else
5813 /* The caller will deal with these. */
5823 {
5824 /* If one of the arguments of the operator represents
5825 an invalid use of member function pointer, try to report
5826 a meaningful error ... */
5831 else
5832 {
5833 /* ... Otherwise, report the more generic
5834 "no matching operator found" error */
5837 }
5838 }
5841 }
5842 }
5843 else
5844 {
5847 {
5849 {
5852 }
5854 }
5856 {
5862 else
5868 {
5873 /* This prevents build_new_function_call from discarding this
5874 function during instantiation of the enclosing template. */
5877 /* Specify evaluation order as per P0145R2. */
5880 {
5891 }
5892 }
5893 }
5894 else
5895 {
5896 /* Give any warnings we noticed during overload resolution. */
5898 {
5902 }
5904 /* Check for comparison of different enum types. */
5906 {
5918 {
5922 }
5926 }
5928 /* We need to strip any leading REF_BIND so that bitfields
5929 don't cause errors. This should not remove any important
5930 conversions, because builtins don't apply to class
5931 objects directly. */
5938 {
5942 else
5945 /* We need to call warn_logical_operator before
5946 converting arg2 to a boolean_type, but after
5947 decaying an enumerator to its value. */
5954 }
5956 {
5961 }
5963 }
5964 }
5966 user_defined_result_ready:
5968 /* Free all the conversions we allocated. */
5974 builtin:
5976 {
5991 /* Fall through. */
6004 /* Fall through. */
6037 complain),
6040 /* The caller will deal with these. */
6048 }
6050 }
6052 /* Wrapper for above. */
6054 tree
6058 {
6059 tree ret;
6065 }
6067 /* CALL was returned by some call-building function; extract the actual
6068 CALL_EXPR from any bits that have been tacked on, e.g. by
6069 convert_from_reference. */
6071 tree
6073 {
6084 }
6086 /* Returns true if FN has two parameters, of which the second has type
6087 size_t. */
6089 static bool
6091 {
6103 }
6105 /* True if T, an allocation function, has std::align_val_t as its second
6106 argument. */
6108 bool
6110 {
6116 }
6118 /* Returns true iff T, an element of an OVERLOAD chain, is a usual deallocation
6119 function (3.7.4.2 [basic.stc.dynamic.deallocation]) with a parameter of
6120 std::align_val_t. */
6122 static bool
6124 {
6128 /* A template instance is never a usual deallocation function,
6129 regardless of its signature. */
6145 }
6147 /* Returns true iff T, an element of an OVERLOAD chain, is a usual
6148 deallocation function (3.7.4.2 [basic.stc.dynamic.deallocation]). */
6150 bool
6152 {
6153 /* A template instance is never a usual deallocation function,
6154 regardless of its signature. */
6159 /* If a class T has a member deallocation function named operator delete
6160 with exactly one parameter, then that function is a usual
6161 (non-placement) deallocation function. If class T does not declare
6162 such an operator delete but does declare a member deallocation
6163 function named operator delete with exactly two parameters, the second
6164 of which has type std::size_t (18.2), then this function is a usual
6165 deallocation function. */
6177 }
6179 /* Build a call to operator delete. This has to be handled very specially,
6180 because the restrictions on what signatures match are different from all
6181 other call instances. For a normal delete, only a delete taking (void *)
6182 or (void *, size_t) is accepted. For a placement delete, only an exact
6183 match with the placement new is accepted.
6185 CODE is either DELETE_EXPR or VEC_DELETE_EXPR.
6186 ADDR is the pointer to be deleted.
6187 SIZE is the size of the memory block to be deleted.
6188 GLOBAL_P is true if the delete-expression should not consider
6189 class-specific delete operators.
6190 PLACEMENT is the corresponding placement new call, or NULL_TREE.
6192 If this call to "operator delete" is being generated as part to
6193 deallocate memory allocated via a new-expression (as per [expr.new]
6194 which requires that if the initialization throws an exception then
6195 we call a deallocation function), then ALLOC_FN is the allocation
6196 function. */
6198 tree
6202 {
6216 /* In [class.free]
6218 If the result of the lookup is ambiguous or inaccessible, or if
6219 the lookup selects a placement deallocation function, the
6220 program is ill-formed.
6222 Therefore, we ask lookup_fnfields to complain about ambiguity. */
6223 {
6227 }
6228 else
6234 /* Strip const and volatile from addr. */
6238 {
6239 /* "A declaration of a placement deallocation function matches the
6240 declaration of a placement allocation function if it has the same
6241 number of parameters and, after parameter transformations (8.3.5),
6242 all parameter types except the first are identical."
6244 So we build up the function type we want and ask instantiate_type
6245 to get it for us. */
6256 /* "If the lookup finds the two-parameter form of a usual deallocation
6257 function (3.7.4.2) and that function, considered as a placement
6258 deallocation function, would have been selected as a match for the
6259 allocation function, the program is ill-formed." */
6261 {
6269 /* But if the class has an operator delete (void *), then that is
6270 the usual deallocation function, so we shouldn't complain
6271 about using the operator delete (void *, size_t). */
6275 {
6280 }
6281 /* Before C++14 a two-parameter global deallocation function is
6282 always a placement deallocation function, but warn if
6283 -Wc++14-compat. */
6285 {
6290 }
6293 {
6295 {
6296 /* Only mention C++14 for namespace-scope delete. */
6299 else
6301 "%qD is a usual (non-placement) deallocation "
6303 }
6304 }
6305 else
6307 ok:;
6308 }
6309 }
6310 else
6311 /* "Any non-placement deallocation function matches a non-placement
6312 allocation function. If the lookup finds a single matching
6313 deallocation function, that function will be called; otherwise, no
6314 deallocation function will be called." */
6316 {
6319 {
6321 {
6324 }
6326 /* -- If the type has new-extended alignment, a function with a
6327 parameter of type std::align_val_t is preferred; otherwise a
6328 function without such a parameter is preferred. If exactly one
6329 preferred function is found, that function is selected and the
6330 selection process terminates. If more than one preferred
6331 function is found, all non-preferred functions are eliminated
6332 from further consideration. */
6334 {
6340 {
6344 }
6345 }
6347 /* -- If the deallocation functions have class scope, the one
6348 without a parameter of type std::size_t is selected. */
6353 /* -- If the type is complete and if, for the second alternative
6354 (delete array) only, the operand is a pointer to a class type
6355 with a non-trivial destructor or a (possibly multi-dimensional)
6356 array thereof, the function with a parameter of type std::size_t
6357 is selected.
6359 -- Otherwise, it is unspecified whether a deallocation function
6360 with a parameter of type std::size_t is selected. */
6361 else
6362 {
6366 /* We need a cookie to determine the array size. */
6368 }
6374 }
6375 }
6377 /* If we have a matching function, call it. */
6379 {
6382 /* If the FN is a member function, make sure that it is
6383 accessible. */
6386 complain);
6388 /* Core issue 901: It's ok to new a type with deleted delete. */
6393 {
6394 /* The placement args might not be suitable for overload
6395 resolution at this point, so build the call directly. */
6405 }
6406 else
6407 {
6408 tree ret;
6414 {
6417 }
6421 }
6422 }
6424 /* [expr.new]
6426 If no unambiguous matching deallocation function can be found,
6427 propagating the exception does not cause the object's memory to
6428 be freed. */
6430 {
6434 alloc_fn);
6436 }
6442 }
6444 /* If the current scope isn't allowed to access DECL along
6445 BASETYPE_PATH, give an error. The most derived class in
6446 BASETYPE_PATH is the one used to qualify DECL. DIAG_DECL is
6447 the declaration to use in the error diagnostic. */
6449 bool
6452 {
6457 {
6458 /* 7.3.3/18: The additional constructors are accessible if they would be
6459 accessible when used to construct an object of the corresponding base
6460 class. */
6464 }
6467 {
6469 {
6473 {
6479 }
6481 {
6487 }
6488 else
6489 {
6494 }
6495 }
6497 }
6500 }
6502 /* Initialize a temporary of type TYPE with EXPR. The FLAGS are a
6503 bitwise or of LOOKUP_* values. If any errors are warnings are
6504 generated, set *DIAGNOSTIC_FN to "error" or "warning",
6505 respectively. If no diagnostics are generated, set *DIAGNOSTIC_FN
6506 to NULL. */
6508 static tree
6511 {
6517 /* If the source is a packed field, calling the copy constructor will require
6518 binding the field to the reference parameter to the copy constructor, and
6519 we'll end up with an infinite loop. If we can use a bitwise copy, then
6520 do that now. */
6536 }
6538 /* Perform warnings about peculiar, but valid, conversions from/to NULL.
6539 EXPR is implicitly converted to type TOTYPE.
6540 FN and ARGNUM are used for diagnostics. */
6542 static void
6544 {
6545 /* Issue warnings about peculiar, but valid, uses of NULL. */
6548 {
6549 source_location loc =
6556 else
6559 }
6561 /* Issue warnings if "false" is converted to a NULL pointer */
6564 {
6567 "converting %<false%> to pointer type for argument %P "
6569 else
6572 }
6573 }
6575 /* We gave a diagnostic during a conversion. If this was in the second
6576 standard conversion sequence of a user-defined conversion sequence, say
6577 which user-defined conversion. */
6579 static void
6581 {
6585 {
6589 }
6590 }
6592 /* Locate the parameter with the given index within FNDECL.
6593 ARGNUM is zero based, -1 indicates the `this' argument of a method.
6594 Return the location of the FNDECL itself if there are problems. */
6596 static location_t
6598 {
6600 tree param;
6602 /* Locate param by index within DECL_ARGUMENTS (fndecl). */
6606 ;
6608 /* If something went wrong (e.g. if we have a builtin and thus no arguments),
6609 return the location of FNDECL. */
6614 }
6616 /* Perform the conversions in CONVS on the expression EXPR. FN and
6617 ARGNUM are used for diagnostics. ARGNUM is zero based, -1
6618 indicates the `this' argument of a method. INNER is nonzero when
6619 being called to continue a conversion chain. It is negative when a
6620 reference binding will be applied, positive otherwise. If
6621 ISSUE_CONVERSION_WARNINGS is true, warnings about suspicious
6622 conversions will be emitted if appropriate. If C_CAST_P is true,
6623 this conversion is coming from a C-style cast; in that case,
6624 conversions to inaccessible bases are permitted. */
6626 static tree
6630 {
6632 diagnostic_t diag_kind;
6648 {
6652 /* Give a helpful error if this is bad because of excess braces. */
6657 {
6663 }
6665 /* Give a helpful error if this is bad because a conversion to bool
6666 from std::nullptr_t requires direct-initialization. */
6674 {
6676 {
6679 totype);
6685 complain);
6689 complain);
6690 else
6696 }
6698 {
6702 complain);
6704 }
6709 complain);
6712 }
6721 }
6727 {
6729 {
6733 /* We chose the surrogate function from add_conv_candidate, now we
6734 actually need to build the conversion. */
6740 /* When converting from an init list we consider explicit
6741 constructors, but actually trying to call one is an error. */
6744 /* Unless this is for direct-list-initialization. */
6746 /* And in C++98 a default constructor can't be explicit. */
6748 {
6754 {
6760 }
6761 else
6764 }
6766 /* If we're initializing from {}, it's value-initialization. */
6770 {
6777 {
6780 }
6782 }
6786 /* Pass LOOKUP_NO_CONVERSION so rvalue/base handling knows not to allow
6787 any more UDCs. */
6789 complain);
6791 /* If this is a constructor or a function returning an aggr type,
6792 we need to build up a TARGET_EXPR. */
6794 {
6797 /* Remember that this was list-initialization. */
6800 }
6803 }
6806 {
6812 else
6814 }
6823 /* If __null has been converted to an integer type, we do not want to
6824 continue to warn about uses of EXPR as an integer, rather than as a
6825 pointer. */
6829 /* We leave bad_p off ck_ambig because overload resolution considers
6830 it valid, it just fails when we try to perform it. So we need to
6831 check complain here, too. */
6833 {
6834 /* Call build_user_type_conversion again for the error. */
6836 complain);
6840 }
6844 {
6845 /* Conversion to std::initializer_list<T>. */
6853 /* Convert all the elements. */
6855 {
6866 }
6867 /* Build up the array. */
6868 elttype = cp_build_qualified_type
6872 /* Take the address explicitly rather than via decay_conversion
6873 to avoid the error about taking the address of a temporary. */
6879 /* Build up the initializer_list object. */
6887 }
6891 {
6900 }
6903 complain);
6910 };
6920 {
6924 {
6926 {
6931 }
6933 }
6938 /* Don't introduce copies when passing arguments along to the inherited
6939 constructor. */
6941 && flag_new_inheriting_ctors
6947 /* Copy-list-initialization doesn't actually involve a copy. */
6950 /* Fall through. */
6953 {
6954 /* We are going to bind a reference directly to a base-class
6955 subobject of EXPR. */
6956 /* Build an expression for `*((base*) &expr)'. */
6960 }
6962 /* Copy-initialization where the cv-unqualified version of the source
6963 type is the same class as, or a derived class of, the class of the
6964 destination [is treated as direct-initialization]. [dcl.init] */
6967 /* This conversion is being done in the context of a user-defined
6968 conversion (i.e. the second step of copy-initialization), so
6969 don't allow any more. */
6971 else
6974 /* standard_conversion got LOOKUP_PREFER_RVALUE. */
6978 {
6983 }
6988 {
6992 {
7005 else
7012 }
7014 /* If necessary, create a temporary.
7016 VA_ARG_EXPR and CONSTRUCTOR expressions are special cases
7017 that need temporaries, even when their types are reference
7018 compatible with the type of reference being bound, so the
7019 upcoming call to cp_build_addr_expr doesn't fail. */
7023 {
7024 /* Otherwise, a temporary of type "cv1 T1" is created and
7025 initialized from the initializer expression using the rules
7026 for a non-reference copy-initialization (8.5). */
7035 {
7036 /* If the reference is volatile or non-const, we
7037 cannot create a temporary. */
7044 else
7048 }
7049 /* If the source is a packed field, and we must use a copy
7050 constructor, then building the target expr will require
7051 binding the field to the reference parameter to the
7052 copy constructor, and we'll end up with an infinite
7053 loop. If we can use a bitwise copy, then we'll be
7054 OK. */
7058 {
7062 }
7064 {
7067 }
7069 }
7071 /* Take the address of the thing to which we will bind the
7072 reference. */
7077 /* Convert it to a pointer to the type referred to by the
7078 reference. This will adjust the pointer if a derived to
7079 base conversion is being performed. */
7082 /* Convert the pointer to the desired reference type. */
7084 }
7090 /* ??? Should the address of a transaction-safe pointer point to the TM
7091 clone, and this conversion look up the primary function? */
7095 /* Warn about deprecated conversion if appropriate. */
7111 }
7119 else
7123 }
7125 /* ARG is being passed to a varargs function. Perform any conversions
7126 required. Return the converted value. */
7128 tree
7130 {
7131 tree arg_type;
7134 /* [expr.call]
7136 The lvalue-to-rvalue, array-to-pointer, and function-to-pointer
7137 standard conversions are performed. */
7140 /* [expr.call]
7142 If the argument has integral or enumeration type that is subject
7143 to the integral promotions (_conv.prom_), or a floating point
7144 type that is subject to the floating point promotion
7145 (_conv.fpprom_), the value of the argument is converted to the
7146 promoted type before the call. */
7151 {
7155 "implicit conversion from %qH to %qI when passing "
7159 }
7163 {
7165 {
7167 complain);
7177 }
7178 else
7180 }
7186 /* In a template (or ill-formed code), we can have an incomplete type
7187 even after require_complete_type_sfinae, in which case we don't know
7188 whether it has trivial copy or not. */
7191 {
7192 /* [expr.call] 5.2.2/7:
7193 Passing a potentially-evaluated argument of class type (Clause 9)
7194 with a non-trivial copy constructor or a non-trivial destructor
7195 with no corresponding parameter is conditionally-supported, with
7196 implementation-defined semantics.
7198 We support it as pass-by-invisible-reference, just like a normal
7199 value parameter.
7201 If the call appears in the context of a sizeof expression,
7202 it is not potentially-evaluated. */
7205 {
7209 "passing objects of non-trivially-copyable "
7211 arg_type);
7213 }
7214 /* Build up a real lvalue-to-rvalue conversion in case the
7215 copy constructor is trivial but not callable. */
7219 }
7222 }
7224 /* va_arg (EXPR, TYPE) is a builtin. Make sure it is not abused. */
7226 tree
7228 {
7230 {
7234 }
7244 {
7247 }
7251 {
7252 /* conditionally-supported behavior [expr.call] 5.2.2/7. Let's treat
7253 it as pass by invisible reference. */
7255 "receiving objects of non-trivially-copyable type %q#T "
7261 }
7265 /* Wrap the VA_ARG_EXPR in a TARGET_EXPR now so other code doesn't need to
7266 know how to handle it. */
7269 }
7271 /* TYPE has been given to va_arg. Apply the default conversions which
7272 would have happened when passed via ellipsis. Return the promoted
7273 type, or the passed type if there is no change. */
7275 tree
7277 {
7278 tree promote;
7280 /* Perform the array-to-pointer and function-to-pointer
7281 conversions. */
7289 }
7291 /* ARG is a default argument expression being passed to a parameter of
7292 the indicated TYPE, which is a parameter to FN. PARMNUM is the
7293 zero-based argument number. Do any required conversions. Return
7294 the converted value. */
7297 void
7301 void
7305 tree
7307 tsubst_flags_t complain)
7308 {
7310 tree t;
7312 /* See through clones. */
7314 /* And inheriting ctors. */
7318 /* Detect recursion. */
7321 {
7325 }
7327 /* If the ARG is an unparsed default argument expression, the
7328 conversion cannot be performed. */
7330 {
7335 }
7342 /* Due to:
7344 [dcl.fct.default]
7346 The names in the expression are bound, and the semantic
7347 constraints are checked, at the point where the default
7348 expressions appears.
7350 we must not perform access checks here. */
7352 /* We must make a copy of ARG, in case subsequent processing
7353 alters any part of it. */
7357 complain);
7364 }
7366 /* Returns the type which will really be used for passing an argument of
7367 type TYPE. */
7369 tree
7371 {
7372 /* Pass classes with copy ctors by invisible reference. */
7374 {
7376 /* There are no other pointers to this temporary. */
7378 }
7386 }
7388 /* Actually perform the appropriate conversion. */
7390 tree
7392 {
7393 tree bitfield_type;
7395 /* If VAL is a bitfield, then -- since it has already been converted
7396 to TYPE -- it cannot have a precision greater than TYPE.
7398 If it has a smaller precision, we must widen it here. For
7399 example, passing "int f:3;" to a function expecting an "int" will
7400 not result in any conversion before this point.
7402 If the precision is the same we must not risk widening. For
7403 example, the COMPONENT_REF for a 32-bit "long long" bitfield will
7404 often have type "int", even though the C++ type for the field is
7405 "long long". If the value is being passed to a function
7406 expecting an "int", then no conversions will be required. But,
7407 if we call convert_bitfield_to_declared_type, the bitfield will
7408 be converted to "long long". */
7415 ;
7416 /* Pass classes with copy ctors by invisible reference. */
7425 {
7427 {
7435 "argument of function call might be a candidate "
7437 }
7439 }
7441 }
7443 /* Returns non-zero iff FN is a function with magic varargs, i.e. ones for
7444 which just decay_conversion or no conversions at all should be done.
7445 This is true for some builtins which don't act like normal functions.
7446 Return 2 if no conversions at all should be done, 1 if just
7447 decay_conversion. Return 3 for special treatment of the 3rd argument
7448 for __builtin_*_overflow_p. */
7450 int
7452 {
7455 {
7470 }
7473 }
7475 /* Returns the decl of the dispatcher function if FN is a function version. */
7477 tree
7479 {
7489 {
7493 }
7498 }
7500 /* fn is a function version dispatcher that is marked used. Mark all the
7501 semantically identical function versions it will dispatch as used. */
7503 void
7505 {
7522 /* All semantically identical versions are chained. Traverse and mark each
7523 one of them as used. */
7526 {
7529 }
7530 }
7532 /* Build a call to "the copy constructor" for the type of A, even if it
7533 wouldn't be selected by normal overload resolution. Used for
7534 diagnostics. */
7536 static tree
7538 {
7549 }
7551 /* Return true iff T refers to a base field. */
7553 static bool
7555 {
7564 }
7566 /* We can't elide a copy from a function returning by value to a base
7567 subobject, as the callee might clobber tail padding. Return true iff this
7568 could be that case. */
7570 static bool
7572 {
7573 /* Copy elision only happens with a TARGET_EXPR. */
7577 /* It's safe to elide the copy for a class with no tail padding. */
7580 /* It's safe to elide the copy if we aren't initializing a base object. */
7584 /* build_compound_expr pushes COMPOUND_EXPR inside TARGET_EXPR. */
7588 {
7589 /* We'll end up copying from each of the arms of the COND_EXPR directly
7590 into the target, so look at them. */
7595 }
7598 }
7600 /* Subroutine of the various build_*_call functions. Overload resolution
7601 has chosen a winning candidate CAND; build up a CALL_EXPR accordingly.
7602 ARGS is a TREE_LIST of the unconverted arguments to the call. FLAGS is a
7603 bitmask of various LOOKUP_* flags which apply to the call itself. */
7605 static tree
7607 {
7615 tree val;
7624 /* In a template, there is no need to perform all of the work that
7625 is normally done. We are only interested in the type of the call
7626 expression, i.e., the return type of the function. Any semantic
7627 errors will be deferred until the template is instantiated. */
7629 {
7631 tree return_type;
7637 else
7638 /* Otherwise set TREE_USED for the benefit of -Wunused-function.
7639 See PR80598. */
7646 else
7647 {
7650 tree arg;
7658 }
7668 }
7670 /* Give any warnings we noticed during overload resolution. */
7672 {
7676 }
7678 /* OK, we're actually calling this inherited constructor; set its deletedness
7679 appropriately. We can get away with doing this here because calling is
7680 the only way to refer to a constructor. */
7684 /* Make =delete work with SFINAE. */
7686 {
7690 }
7693 {
7694 tree access_fn;
7695 /* If FN is a template function, two cases must be considered.
7696 For example:
7698 struct A {
7699 protected:
7700 template <class T> void f();
7701 };
7702 template <class T> struct B {
7703 protected:
7704 void g();
7705 };
7706 struct C : A, B<int> {
7707 using A::f; // #1
7708 using B<int>::g; // #2
7709 };
7711 In case #1 where `A::f' is a member template, DECL_ACCESS is
7712 recorded in the primary template but not in its specialization.
7713 We check access of FN using its primary template.
7715 In case #2, where `B<int>::g' has a DECL_TEMPLATE_INFO simply
7716 because it is a member of class template B, DECL_ACCESS is
7717 recorded in the specialization `B<int>::g'. We cannot use its
7718 primary template because `B<T>::g' and `B<int>::g' may have
7719 different access. */
7723 else
7728 }
7730 /* If we're checking for implicit delete, don't bother with argument
7731 conversions. */
7733 {
7737 /* Reject bad conversions now. */
7739 /* else continue to get conversion error. */
7740 }
7742 /* N3276 magic doesn't apply to nested calls. */
7745 /* No-Cleanup doesn't apply to nested calls either. */
7749 /* Find maximum size of vector to hold converted arguments. */
7756 /* The implicit parameters to a constructor are not considered by overload
7757 resolution, and must be of the proper type. */
7759 {
7760 tree object_arg;
7762 {
7765 }
7766 else
7767 {
7770 }
7773 /* We should never try to call the abstract constructor. */
7777 {
7781 }
7784 {
7785 /* The implicit move specified in 15.8.3/3 fails "...if the type of
7786 the first parameter of the selected constructor is not an rvalue
7787 reference to the object’s type (possibly cv-qualified)...." */
7794 }
7795 }
7796 /* Bypass access control for 'this' parameter. */
7798 {
7801 ? first_arg
7804 tree converted_arg;
7805 tree base_binfo;
7811 {
7813 {
7818 }
7819 else
7821 }
7823 /* See if the function member or the whole class type is declared
7824 final and the call can be devirtualized. */
7829 /* [class.mfct.nonstatic]: If a nonstatic member function of a class
7830 X is called for an object that is not of type X, or of a type
7831 derived from X, the behavior is undefined.
7833 So we can assume that anything passed as 'this' is non-null, and
7834 optimize accordingly. */
7836 /* Convert to the base in which the function was declared. */
7839 arg,
7842 /* Check that the base class is accessible. */
7845 {
7850 else
7852 }
7853 /* If fn was found by a using declaration, the conversion path
7854 will be to the derived class, not the base declaring fn. We
7855 must convert from derived to base. */
7866 else
7870 }
7875 {
7882 /* If the argument is NULL and used to (implicitly) instantiate a
7883 template function (and bind one of the template arguments to
7884 the type of 'long int'), we don't want to warn about passing NULL
7885 to non-pointer argument.
7886 For example, if we have this template function:
7888 template<typename T> void func(T x) {}
7890 we want to warn (when -Wconversion is enabled) in this case:
7892 void foo() {
7893 func<int>(NULL);
7894 }
7896 but not in this case:
7898 void foo() {
7899 func(NULL);
7900 }
7901 */
7908 /* Warn about initializer_list deduction that isn't currently in the
7909 working draft. */
7911 && flag_deduce_init_list
7915 {
7928 {
7936 }
7937 }
7939 /* Set user_conv_p on the argument conversions, so rvalue/base handling
7940 knows not to allow any more UDCs. This needs to happen after we
7941 process cand->warnings. */
7950 arg_complain);
7955 else
7957 }
7959 /* Default arguments */
7961 {
7967 complain);
7971 }
7973 /* Ellipsis */
7976 {
7979 {
7980 /* Do no conversions for certain magic varargs. */
7984 }
7986 /* For other magic varargs only do decay_conversion. */
7991 {
7992 /* Avoid infinite recursion trying to call A(...). */
7994 /* Try to call the actual copy constructor for a good error. */
7997 }
7998 else
8003 }
8008 /* Avoid to do argument-transformation, if warnings for format, and for
8009 nonnull are disabled. Just in case that at least one of them is active
8010 the check_function_arguments function might warn about something. */
8014 || warn_format
8015 || warn_suggest_attribute_format
8017 {
8025 }
8028 {
8029 /* Check for passing ellipsis arguments to an inherited constructor. We
8030 could handle this by open-coding the inherited constructor rather than
8031 defining it, but let's not bother now. */
8035 {
8037 {
8041 }
8043 }
8045 /* A base constructor inheriting from a virtual base doesn't get the
8046 inherited arguments, just this and __vtt. */
8049 }
8051 /* Avoid actually calling copy constructors and copy assignment operators,
8052 if possible. */
8059 /* It's unsafe to elide the constructor when handling
8060 a noexcept-expression, it may evaluate to the wrong
8061 value (c++/53025). */
8063 {
8064 tree targ;
8066 tree fa;
8069 /* Pull out the real argument, disregarding const-correctness. */
8071 /* Strip the reference binding for the constructor parameter. */
8075 /* But don't strip any other reference bindings; binding a temporary to a
8076 reference prevents copy elision. */
8082 {
8087 }
8088 else
8093 else
8096 /* In C++17 we shouldn't be copying a TARGET_EXPR except into a base
8097 subobject. */
8100 /* It's from binding the ref parm to a packed field. */
8103 /* See unsafe_copy_elision_p. */
8106 /* [class.copy]: the copy constructor is implicitly defined even if
8107 the implementation elided its use. */
8109 {
8113 }
8115 /* If we're creating a temp and we already have one, don't create a
8116 new one. If we're not creating a temp but we get one, use
8117 INIT_EXPR to collapse the temp into our target. Otherwise, if the
8118 ctor is trivial, do a bitwise copy with a simple TARGET_EXPR for a
8119 temp or an INIT_EXPR otherwise. */
8122 {
8127 }
8130 {
8135 }
8136 }
8140 {
8141 tree to = cp_stabilize_reference
8148 {
8149 /* Avoid copying empty classes. */
8152 }
8154 {
8157 /* Handle NSDMI that refer to the object being initialized. */
8159 }
8160 else
8161 {
8162 /* We must only copy the non-tail padding parts. */
8170 build_index_type
8179 }
8182 }
8184 {
8188 {
8191 no_cleanup_complain);
8192 else
8194 }
8195 }
8197 /* For calls to a multi-versioned function, overload resolution
8198 returns the function with the highest target priority, that is,
8199 the version that will checked for dispatching first. If this
8200 version is inlinable, a direct call to this version can be made
8201 otherwise the call should go through the dispatcher. */
8206 {
8212 }
8218 /* Warn if the built-in writes to an object of a non-trivial type. */
8225 /* Don't mess with virtual lookup in instantiate_non_dependent_expr;
8226 virtual functions can't be constexpr. */
8228 {
8229 tree t;
8236 complain);
8242 }
8243 else
8244 {
8248 }
8254 {
8256 /* build_new_op_1 will clear this when appropriate. */
8258 }
8260 {
8264 }
8266 }
8268 /* Return the DECL of the first non-public data member of class TYPE
8269 or null if none can be found. */
8271 static tree
8273 {
8278 {
8285 }
8291 {
8296 }
8299 }
8301 /* Return true if all copy and move assignment operator overloads for
8302 class TYPE are trivial and at least one of them is not deleted and,
8303 when ACCESS is set, accessible. Return false otherwise. Set
8304 HASASSIGN to true when the TYPE has a (not necessarily trivial)
8305 copy or move assignment. */
8307 static bool
8309 {
8313 /* Iterate over overloads of the assignment operator, checking
8314 accessible copy assignments for triviality. */
8317 {
8320 /* Skip operators that aren't copy assignments. */
8327 /* Skip template assignment operators and deleted functions. */
8337 /* Break early when both properties have been determined. */
8340 }
8342 /* Return true if they're all trivial and one of the expressions
8343 TYPE() = TYPE() or TYPE() = (TYPE&)() is valid. */
8348 }
8350 /* Return true if all copy and move ctor overloads for class TYPE are
8351 trivial and at least one of them is not deleted and, when ACCESS is
8352 set, accessible. Return false otherwise. Set each element of HASCTOR[]
8353 to true when the TYPE has a (not necessarily trivial) default and copy
8354 (or move) ctor, respectively. */
8356 static bool
8358 {
8363 {
8366 /* Skip template constructors. */
8372 /* Skip ctors other than default, copy, and move. */
8388 /* Break early when both properties have been determined. */
8391 }
8394 }
8396 /* Issue a warning on a call to the built-in function FNDECL if it is
8397 a raw memory write whose destination is not an object of (something
8398 like) trivial or standard layout type with a non-deleted assignment
8399 and copy ctor. Detects const correctness violations, corrupting
8400 references, virtual table pointers, and bypassing non-trivial
8401 assignments. */
8403 static void
8406 {
8407 /* Except for bcopy where it's second, the destination pointer is
8408 the first argument for all functions handled here. Compute
8409 the index of the destination and source arguments. */
8419 /* Determine the type of the pointed-to object and whether it's
8420 a complete class type. */
8426 /* Check to see if the raw memory call is made by a ctor or dtor
8427 with this as the destination argument for the destination type.
8428 If so, be more permissive. */
8433 {
8439 /* A ctor and dtor for a class with no bases and no virtual functions
8440 can do whatever they want. Bail early with no further checking. */
8443 }
8445 /* True if the class is trivial. */
8448 /* Set to true if DESTYPE has an accessible copy assignment. */
8450 /* True if all of the class' overloaded copy assignment operators
8451 are all trivial (and not deleted) and at least one of them is
8452 accessible. */
8455 /* Set to true if DESTTYPE has an accessible default and copy ctor,
8456 respectively. */
8459 /* True if all of the class' overloaded copy constructors are all
8460 trivial (and not deleted) and at least one of them is accessible. */
8463 /* Set FLD to the first private/protected member of the class. */
8466 /* The warning format string. */
8468 /* A suggested alternative to offer instead of the raw memory call.
8469 Empty string when none can be come up with. */
8474 {
8477 {
8478 /* Diagnose setting non-copy-assignable or non-trivial types,
8479 or types with a private member, to (potentially) non-zero
8480 bytes. Since the value of the bytes being written is unknown,
8481 suggest using assignment instead (if one exists). Also warn
8482 for writes into objects for which zero-initialization doesn't
8483 mean all bits clear (pointer-to-member data, where null is all
8484 bits set). Since the value being written is (most likely)
8485 non-zero, simply suggest assignment (but not copy assignment). */
8493 {
8496 "%qD writing to an object of type %#qT with "
8499 }
8505 }
8506 /* Fall through. */
8509 /* Similarly to the above, diagnose clearing non-trivial or non-
8510 standard layout objects, or objects of types with no assignmenmt.
8511 Since the value being written is known to be zero, suggest either
8512 copy assignment, copy ctor, or default ctor as an alternative,
8513 depending on what's available. */
8536 /* Determine the type of the source object. */
8540 else
8543 /* Since it's impossible to determine wheter the byte copy is
8544 being used in place of assignment to an existing object or
8545 as a substitute for initialization, assume it's the former.
8546 Determine the best alternative to use instead depending on
8547 what's not deleted. */
8568 srctype))
8569 {
8570 /* Warn when copying into a non-trivial object from an object
8571 of a different type other than void or char. */
8573 "%qD copying an object of non-trivial type "
8576 }
8581 srctype))
8582 {
8585 "%qD copying an object of type %#qT with "
8586 "%qs member %qD from an array of %#qT; use "
8589 }
8591 {
8596 /* Finally, warn on partial copies. */
8597 unsigned HOST_WIDE_INT typesize
8603 "a non-trivial type %#qT leaves %wu "
8606 "a non-trivial type %#qT leaves %wu "
8609 }
8624 {
8628 /* Finally, warn on reallocation into insufficient space. */
8630 "%qD moving an object of non-trivial type "
8633 sz);
8634 }
8639 }
8642 {
8646 else
8649 }
8653 }
8655 /* Build and return a call to FN, using NARGS arguments in ARGARRAY.
8656 This function performs no overload resolution, conversion, or other
8657 high-level operations. */
8659 tree
8661 tsubst_flags_t complain)
8662 {
8663 tree fndecl;
8665 /* Remember roughly where this call is. */
8672 /* Check that arguments to builtin functions match the expectations. */
8676 {
8679 /* We need to take care that values to BUILT_IN_NORMAL
8680 are reduced. */
8687 }
8692 /* 5.2.2/11: If a function call is a prvalue of object type: if the
8693 function call is either the operand of a decltype-specifier or the
8694 right operand of a comma operator that is the operand of a
8695 decltype-specifier, a temporary object is not introduced for the
8696 prvalue. The type of the prvalue may be incomplete. */
8698 {
8704 {
8707 }
8708 }
8710 }
8712 /* Returns the value to use for the in-charge parameter when making a
8713 call to a function with the indicated NAME.
8715 FIXME:Can't we find a neater way to do this mapping? */
8717 tree
8719 {
8721 {
8725 }
8726 else
8727 {
8733 }
8736 }
8738 /* We've built up a constructor call RET. Complain if it delegates to the
8739 constructor we're currently compiling. */
8741 static void
8743 {
8749 }
8751 /* Build a call to a constructor, destructor, or an assignment
8752 operator for INSTANCE, an expression with class type. NAME
8753 indicates the special member function to call; *ARGS are the
8754 arguments. ARGS may be NULL. This may change ARGS. BINFO
8755 indicates the base of INSTANCE that is to be passed as the `this'
8756 parameter to the member function called.
8758 FLAGS are the LOOKUP_* flags to use when processing the call.
8760 If NAME indicates a complete object constructor, INSTANCE may be
8761 NULL_TREE. In this case, the caller will call build_cplus_new to
8762 store the newly constructed object into a VAR_DECL. */
8764 tree
8767 {
8768 tree fns;
8769 /* The type of the subobject to be constructed or destroyed. */
8770 tree class_type;
8772 tree ret;
8776 {
8777 /* Resolve the name. */
8782 }
8788 /* Handle the special case where INSTANCE is NULL_TREE. */
8791 else
8792 {
8796 /* Convert to the base class, if necessary. */
8799 {
8801 /* For constructors and destructors, either the base is
8802 non-virtual, or it is virtual but we are doing the
8803 conversion from a constructor or destructor for the
8804 complete object. In either case, we can convert
8805 statically. */
8807 else
8808 {
8809 /* However, for assignment operators, we must convert
8810 dynamically if the base is virtual. */
8814 }
8815 }
8816 }
8820 /* In C++17, "If the initializer expression is a prvalue and the
8821 cv-unqualified version of the source type is the same class as the class
8822 of the destination, the initializer expression is used to initialize the
8823 destination object." Handle that here to avoid doing overload
8824 resolution. */
8828 {
8831 /* FIXME P0135 doesn't say how to handle direct initialization from a
8832 type with a suitable conversion operator. Let's handle it like
8833 copy-initialization, but allowing explict conversions. */
8836 /* If we're using this to initialize a non-temporary object, don't
8837 require the destructor to be accessible. */
8841 sub_complain,
8842 flags);
8845 && (same_type_ignoring_top_level_qualifiers_p
8847 {
8856 /* Avoid change of behavior on Wunused-var-2.C. */
8859 }
8860 }
8864 /* When making a call to a constructor or destructor for a subobject
8865 that uses virtual base classes, pass down a pointer to a VTT for
8866 the subobject. */
8870 {
8871 tree vtt;
8872 tree sub_vtt;
8874 /* If the current function is a complete object constructor
8875 or destructor, then we fetch the VTT directly.
8876 Otherwise, we look it up using the VTT we were given. */
8884 else
8888 {
8891 }
8894 }
8899 complain);
8910 }
8912 /* Return the NAME, as a C string. The NAME indicates a function that
8913 is a member of TYPE. *FREE_P is set to true if the caller must
8914 free the memory returned.
8916 Rather than go through all of this, we should simply set the names
8917 of constructors and destructors appropriately, and dispense with
8918 ctor_identifier, dtor_identifier, etc. */
8922 {
8925 /* Assume that we will not allocate memory. */
8927 /* Constructors and destructors are special. */
8929 {
8930 pretty_name
8932 /* For a destructor, add the '~'. */
8934 {
8936 /* Remember that we need to free the memory allocated. */
8938 }
8939 }
8941 {
8944 TFF_PLAIN_IDENTIFIER),
8945 NULL);
8946 /* Remember that we need to free the memory allocated. */
8948 }
8949 else
8953 }
8955 /* Build a call to "INSTANCE.FN (ARGS)". If FN_P is non-NULL, it will
8956 be set, upon return, to the function called. ARGS may be NULL.
8957 This may change ARGS. */
8959 static tree
8963 {
8968 tree optype;
8970 tree name;
8973 tree call;
8974 tree fn;
8977 tree orig_instance;
8978 tree orig_fns;
8984 /* We don't know what function we're going to call, yet. */
8993 {
8997 }
9002 /* Dismantle the baselink to collect all the information we need. */
9010 {
9014 }
9025 {
9030 }
9033 /* Under DR 147 A::A() is an invalid constructor call,
9034 not a functional cast. */
9036 {
9048 complain);
9050 }
9052 /* Process the argument list. */
9054 {
9058 }
9060 /* Consider the object argument to be used even if we end up selecting a
9061 static member function. */
9064 /* Figure out whether to skip the first argument for the error
9065 message we will display to users if an error occurs. We don't
9066 want to display any compiler-generated arguments. The "this"
9067 pointer hasn't been added yet. However, we must remove the VTT
9068 pointer if this is a call to a base-class constructor or
9069 destructor. */
9072 {
9073 /* Callers should explicitly indicate whether they want to ctor
9074 the complete object or just the part without virtual bases. */
9077 /* Remove the VTT pointer, if present. */
9082 /* It's OK to call destructors and constructors on cv-qualified
9083 objects. Therefore, convert the INSTANCE to the unqualified
9084 type, if necessary. */
9086 {
9090 }
9091 }
9092 else
9095 /* For the overload resolution we need to find the actual `this`
9096 that would be captured if the call turns out to be to a
9097 non-static member function. Do not actually capture it at this
9098 point. */
9100 /* Constructors don't use the enclosing 'this'. */
9102 else
9105 /* Get the high-water mark for the CONVERSION_OBSTACK. */
9108 /* The number of arguments artificial parms in ARGS; we subtract one because
9109 there's no 'this' in ARGS. */
9112 /* If CONSTRUCTOR_IS_DIRECT_INIT is set, this was a T{ } form
9113 initializer, not T({ }). */
9117 {
9124 /* If the initializer list has no elements and T is a class type with
9125 a default constructor, the object is value-initialized. Handle
9126 this here so we don't need to handle it wherever we use
9127 build_special_member_call. */
9130 /* For a user-provided default constructor, use the normal
9131 mechanisms so that protected access works. */
9136 /* If BASETYPE is an aggregate, we need to do aggregate
9137 initialization. */
9139 {
9142 }
9145 {
9151 }
9153 /* Otherwise go ahead with overload resolution. */
9158 }
9159 else
9168 {
9170 {
9177 else
9178 {
9183 {
9186 }
9194 }
9196 }
9198 }
9199 else
9200 {
9203 {
9206 tree arglist;
9209 {
9217 else
9223 }
9225 }
9226 else
9227 {
9235 {
9236 /* This is not an error, it is runtime undefined
9237 behavior. */
9246 fn);
9247 }
9252 {
9257 {
9258 /* We captured 'this' in the current lambda now that
9259 we know we really need it. */
9261 }
9263 /* We can't tell until instantiation time whether we can use
9265 else
9266 {
9269 fn);
9271 }
9272 }
9275 {
9276 /* Optimize away vtable lookup if we know that this
9277 function can't be overridden. We need to check if
9278 the context and the type where we found fn are the same,
9279 actually FN might be defined in a different class
9280 type because of a using-declaration. In this case, we
9281 do not want to perform a non-virtual call. */
9283 && same_type_ignoring_top_level_qualifiers_p
9289 /* Now we know what function is being called. */
9292 /* Build the actual CALL_EXPR. */
9294 /* In an expression of the form `a->f()' where `f' turns
9295 out to be a static member function, `a' is
9296 none-the-less evaluated. */
9300 {
9301 /* But avoid the implicit lvalue-rvalue conversion when 'a'
9302 is volatile. */
9307 }
9311 /* An explicit call of the form "x->~X()" has type
9312 "void". However, on platforms where destructors
9313 return "this" (i.e., those where
9314 targetm.cxx.cdtor_returns_this is true), such calls
9315 will appear to have a return value of pointer type
9316 to the low-level call machinery. We do not want to
9317 change the low-level machinery, since we want to be
9318 able to optimize "delete f()" on such platforms as
9319 "operator delete(~X(f()))" (rather than generating
9320 "t = f(), ~X(t), operator delete (t)"). */
9322 }
9323 }
9324 }
9327 {
9333 {
9336 }
9339 call = (build_min_non_dep_call_vec
9343 orig_args));
9348 }
9350 /* Free all the conversions we allocated. */
9357 }
9359 /* Wrapper for above. */
9361 tree
9365 {
9366 tree ret;
9372 }
9374 /* Returns true iff standard conversion sequence ICS1 is a proper
9375 subsequence of ICS2. */
9377 static bool
9379 {
9380 /* We can assume that a conversion of the same code
9381 between the same types indicates a subsequence since we only get
9382 here if the types we are converting from are the same. */
9389 {
9399 /* At this point, ICS1 cannot be a proper subsequence of
9400 ICS2. We can get a USER_CONV when we are comparing the
9401 second standard conversion sequence of two user conversion
9402 sequences. */
9417 }
9418 }
9420 /* Returns nonzero iff DERIVED is derived from BASE. The inputs may
9421 be any _TYPE nodes. */
9423 bool
9425 {
9429 /* We only allow proper derivation here. The DERIVED_FROM_P macro
9430 considers every class derived from itself. */
9433 }
9435 /* We build the ICS for an implicit object parameter as a pointer
9436 conversion sequence. However, such a sequence should be compared
9437 as if it were a reference conversion sequence. If ICS is the
9438 implicit conversion sequence for an implicit object parameter,
9439 modify it accordingly. */
9441 static void
9443 {
9445 {
9446 /* [over.match.funcs]
9448 For non-static member functions, the type of the
9449 implicit object parameter is "reference to cv X"
9450 where X is the class of which the function is a
9451 member and cv is the cv-qualification on the member
9452 function declaration. */
9454 tree reference_type;
9456 /* The `this' parameter is a pointer to a class type. Make the
9457 implicit conversion talk about a reference to that same class
9458 type. */
9471 }
9472 }
9474 /* If *ICS is a REF_BIND set *ICS to the remainder of the conversion,
9475 and return the initial reference binding conversion. Otherwise,
9476 leave *ICS unchanged and return NULL. */
9480 {
9482 {
9487 }
9490 }
9492 /* Compare two implicit conversion sequences according to the rules set out in
9493 [over.ics.rank]. Return values:
9495 1: ics1 is better than ics2
9496 -1: ics2 is better than ics1
9497 0: ics1 and ics2 are indistinguishable */
9499 static int
9501 {
9502 tree from_type1;
9503 tree from_type2;
9504 tree to_type1;
9505 tree to_type2;
9512 /* REF_BINDING is nonzero if the result of the conversion sequence
9513 is a reference type. In that case REF_CONV is the reference
9514 binding conversion. */
9518 /* Compare badness before stripping the reference conversion. */
9524 /* Handle implicit object parameters. */
9528 /* Handle reference parameters. */
9532 /* List-initialization sequence L1 is a better conversion sequence than
9533 list-initialization sequence L2 if L1 converts to
9534 std::initializer_list<X> for some X and L2 does not. */
9540 /* [over.ics.rank]
9542 When comparing the basic forms of implicit conversion sequences (as
9543 defined in _over.best.ics_)
9545 --a standard conversion sequence (_over.ics.scs_) is a better
9546 conversion sequence than a user-defined conversion sequence
9547 or an ellipsis conversion sequence, and
9549 --a user-defined conversion sequence (_over.ics.user_) is a
9550 better conversion sequence than an ellipsis conversion sequence
9551 (_over.ics.ellipsis_). */
9552 /* Use BAD_CONVERSION_RANK because we already checked for a badness
9553 mismatch. If both ICS are bad, we try to make a decision based on
9554 what would have happened if they'd been good. This is not an
9555 extension, we'll still give an error when we build up the call; this
9556 just helps us give a more helpful error message. */
9566 /* Both conversions are ellipsis conversions. */
9569 /* User-defined conversion sequence U1 is a better conversion sequence
9570 than another user-defined conversion sequence U2 if they contain the
9571 same user-defined conversion operator or constructor and if the sec-
9572 ond standard conversion sequence of U1 is better than the second
9573 standard conversion sequence of U2. */
9575 /* Handle list-conversion with the same code even though it isn't always
9576 ranked as a user-defined conversion and it doesn't have a second
9577 standard conversion sequence; it will still have the desired effect.
9578 Specifically, we need to do the reference binding comparison at the
9579 end of this function. */
9582 {
9598 {
9603 }
9604 else
9605 {
9606 /* For ambiguous or aggregate conversions, use the target type as
9607 a proxy for the conversion function. */
9610 }
9612 /* We can just fall through here, after setting up
9613 FROM_TYPE1 and FROM_TYPE2. */
9616 }
9617 else
9618 {
9622 /* We're dealing with two standard conversion sequences.
9624 [over.ics.rank]
9626 Standard conversion sequence S1 is a better conversion
9627 sequence than standard conversion sequence S2 if
9629 --S1 is a proper subsequence of S2 (comparing the conversion
9630 sequences in the canonical form defined by _over.ics.scs_,
9631 excluding any Lvalue Transformation; the identity
9632 conversion sequence is considered to be a subsequence of
9633 any non-identity conversion sequence */
9644 }
9646 /* One sequence can only be a subsequence of the other if they start with
9647 the same type. They can start with different types when comparing the
9648 second standard conversion sequence in two user-defined conversion
9649 sequences. */
9651 {
9656 }
9658 /* [over.ics.rank]
9660 Or, if not that,
9662 --the rank of S1 is better than the rank of S2 (by the rules
9663 defined below):
9665 Standard conversion sequences are ordered by their ranks: an Exact
9666 Match is a better conversion than a Promotion, which is a better
9667 conversion than a Conversion.
9669 Two conversion sequences with the same rank are indistinguishable
9670 unless one of the following rules applies:
9672 --A conversion that does not a convert a pointer, pointer to member,
9673 or std::nullptr_t to bool is better than one that does.
9675 The ICS_STD_RANK automatically handles the pointer-to-bool rule,
9676 so that we do not have to check it explicitly. */
9685 /* A conversion from scalar arithmetic type to complex is worse than a
9686 conversion between scalar arithmetic types. */
9693 {
9696 else
9698 }
9704 {
9709 }
9710 /* The rules for pointers to members A::* are just like the rules
9711 for pointers A*, except opposite: if B is derived from A then
9712 A::* converts to B::*, not vice versa. For that reason, we
9713 switch the from_ and to_ variables here. */
9720 {
9725 }
9730 {
9731 /* This was one of the pointer or pointer-like conversions.
9733 [over.ics.rank]
9735 --If class B is derived directly or indirectly from class A,
9736 conversion of B* to A* is better than conversion of B* to
9737 void*, and conversion of A* to void* is better than
9738 conversion of B* to void*. */
9741 {
9743 deref_from_type2))
9746 deref_from_type1))
9748 }
9751 {
9753 {
9755 {
9757 deref_to_type1))
9759 }
9760 /* We know that DEREF_TO_TYPE1 is `void' here. */
9762 deref_to_type2))
9764 }
9765 }
9768 {
9769 /* [over.ics.rank]
9771 --If class B is derived directly or indirectly from class A
9772 and class C is derived directly or indirectly from B,
9774 --conversion of C* to B* is better than conversion of C* to
9775 A*,
9777 --conversion of B* to A* is better than conversion of C* to
9778 A* */
9780 {
9782 deref_to_type2))
9785 deref_to_type1))
9787 }
9789 {
9791 deref_from_type1))
9794 deref_from_type2))
9796 }
9797 }
9798 }
9801 {
9804 /* [over.ics.rank]
9806 --binding of an expression of type C to a reference of type
9807 B& is better than binding an expression of type C to a
9808 reference of type A&
9810 --conversion of C to B is better than conversion of C to A, */
9813 {
9818 }
9819 }
9822 {
9825 /* [over.ics.rank]
9827 --binding of an expression of type B to a reference of type
9828 A& is better than binding an expression of type C to a
9829 reference of type A&,
9831 --conversion of B to A is better than conversion of C to A */
9834 {
9839 }
9840 }
9842 /* [over.ics.rank]
9844 --S1 and S2 differ only in their qualification conversion and yield
9845 similar types T1 and T2 (_conv.qual_), respectively, and the cv-
9846 qualification signature of type T1 is a proper subset of the cv-
9847 qualification signature of type T2 */
9851 {
9855 }
9857 /* [over.ics.rank]
9859 --S1 and S2 are reference bindings (_dcl.init.ref_) and neither refers
9860 to an implicit object parameter of a non-static member function
9861 declared without a ref-qualifier, and either S1 binds an lvalue
9862 reference to an lvalue and S2 binds an rvalue reference or S1 binds an
9863 rvalue reference to an rvalue and S2 binds an lvalue reference (C++0x
9864 draft standard, 13.3.3.2)
9866 --S1 and S2 are reference bindings (_dcl.init.ref_), and the
9867 types to which the references refer are the same type except for
9868 top-level cv-qualifiers, and the type to which the reference
9869 initialized by S2 refers is more cv-qualified than the type to
9870 which the reference initialized by S1 refers.
9872 DR 1328 [over.match.best]: the context is an initialization by
9873 conversion function for direct reference binding (13.3.1.6) of a
9874 reference to function type, the return type of F1 is the same kind of
9875 reference (i.e. lvalue or rvalue) as the reference being initialized,
9876 and the return type of F2 is not. */
9879 {
9886 {
9890 /* Don't prefer a bad conversion that drops cv-quals to a bad
9891 conversion with the wrong rvalueness. */
9895 }
9898 {
9902 {
9903 /* Prefer the one that drops fewer cv-quals. */
9908 }
9910 }
9911 }
9913 /* Neither conversion sequence is better than the other. */
9915 }
9917 /* The source type for this standard conversion sequence. */
9919 static tree
9921 {
9923 {
9928 }
9930 }
9932 /* Note a warning about preferring WINNER to LOSER. We do this by storing
9933 a pointer to LOSER and re-running joust to produce the warning if WINNER
9934 is actually used. */
9936 static void
9938 {
9944 }
9946 /* Compare two candidates for overloading as described in
9947 [over.match.best]. Return values:
9949 1: cand1 is better than cand2
9950 -1: cand2 is better than cand1
9951 0: cand1 and cand2 are indistinguishable */
9953 static int
9955 tsubst_flags_t complain)
9956 {
9962 /* Candidates that involve bad conversions are always worse than those
9963 that don't. */
9969 /* If we have two pseudo-candidates for conversions to the same type,
9970 or two candidates for the same function, arbitrarily pick one. */
9975 /* Prefer a non-deleted function over an implicitly deleted move
9976 constructor or assignment operator. This differs slightly from the
9977 wording for issue 1402 (which says the move op is ignored by overload
9978 resolution), but this way produces better error messages. */
9982 {
9989 }
9991 /* a viable function F1
9992 is defined to be a better function than another viable function F2 if
9993 for all arguments i, ICSi(F1) is not a worse conversion sequence than
9994 ICSi(F2), and then */
9996 /* for some argument j, ICSj(F1) is a better conversion sequence than
9997 ICSj(F2) */
9999 /* For comparing static and non-static member functions, we ignore
10000 the implicit object parameter of the non-static function. The
10001 standard says to pretend that the static function has an object
10002 parm, but that won't work with operator overloading. */
10005 {
10011 /* We're comparing a near-match list constructor and a near-match
10012 non-list constructor. Just treat them as unordered. */
10019 else
10020 {
10023 }
10024 }
10027 {
10033 {
10035 && warn_sign_promo
10047 {
10054 else
10059 {
10063 }
10064 else
10066 }
10069 {
10072 }
10074 }
10075 }
10077 /* warn about confusing overload resolution for user-defined conversions,
10078 either between a constructor and a conversion op, or between two
10079 conversion ops. */
10084 {
10090 else
10093 /* We don't want to complain about `X::operator T1 ()'
10094 beating `X::operator T2 () const', when T2 is a no less
10095 cv-qualified version of T1. */
10098 {
10103 {
10106 }
10109 }
10110 else
10116 {
10123 {
10125 }
10126 }
10127 else
10129 }
10134 /* DR 495 moved this tiebreaker above the template ones. */
10135 /* or, if not that,
10136 the context is an initialization by user-defined conversion (see
10137 _dcl.init_ and _over.match.user_) and the standard conversion
10138 sequence from the return type of F1 to the destination type (i.e.,
10139 the type of the entity being initialized) is a better conversion
10140 sequence than the standard conversion sequence from the return type
10141 of F2 to the destination type. */
10144 {
10148 }
10150 /* or, if not that,
10151 F1 is a non-template function and F2 is a template function
10152 specialization. */
10159 /* or, if not that,
10160 F1 and F2 are template functions and the function template for F1 is
10161 more specialized than the template for F2 according to the partial
10162 ordering rules. */
10165 {
10166 winner = more_specialized_fn
10169 /* [temp.func.order]: The presence of unused ellipsis and default
10170 arguments has no effect on the partial ordering of function
10171 templates. add_function_candidate() will not have
10172 counted the "this" argument for constructors. */
10176 }
10178 // C++ Concepts
10179 // or, if not that, F1 is more constrained than F2.
10181 {
10185 }
10187 /* F1 is generated from a deduction-guide (13.3.1.8) and F2 is not */
10189 {
10191 /* We distinguish between candidates from an explicit deduction guide and
10192 candidates built from a constructor based on DECL_ARTIFICIAL. */
10199 {
10200 /* Prefer the special copy guide over a declared copy/move
10201 constructor. */
10207 /* Prefer a candidate generated from a non-template constructor. */
10212 }
10213 }
10215 /* F1 is a member of a class D, F2 is a member of a base class B of D, and
10216 for all arguments the corresponding parameters of F1 and F2 have the same
10217 type (CWG 2273/2277). */
10222 {
10236 {
10238 {
10243 }
10246 }
10247 }
10249 /* Check whether we can discard a builtin candidate, either because we
10250 have two identical ones or matching builtin and non-builtin candidates.
10252 (Pedantically in the latter case the builtin which matched the user
10253 function should not be added to the overload set, but we spot it here.
10255 [over.match.oper]
10256 ... the builtin candidates include ...
10257 - do not have the same parameter type list as any non-template
10258 non-member candidate. */
10261 {
10267 {
10269 /* Two built-in candidates; arbitrarily pick one. */
10272 /* cand1 is built-in; prefer cand2. */
10274 else
10275 /* cand2 is built-in; prefer cand1. */
10277 }
10278 }
10280 /* For candidates of a multi-versioned function, make the version with
10281 the highest priority win. This version will be checked for dispatching
10282 first. If this version can be inlined into the caller, the front-end
10283 will simply make a direct call to this function. */
10289 {
10295 /* Check if cand1->fn and cand2->fn are versions of the same function. It
10296 is possible that cand1->fn and cand2->fn are function versions but of
10297 different functions. Check types to see if they are versions of the same
10298 function. */
10301 {
10302 /* Always make the version with the higher priority, more
10303 specialized, win. */
10307 else
10309 }
10310 }
10312 /* If the two function declarations represent the same function (this can
10313 happen with declarations in multiple scopes and arg-dependent lookup),
10314 arbitrarily choose one. But first make sure the default args we're
10315 using match. */
10318 {
10325 {
10326 /* Don't crash if the fn is variadic. */
10331 }
10339 {
10342 {
10344 {
10346 {
10348 "default argument mismatch in "
10350 {
10355 }
10356 }
10357 else
10359 }
10360 else
10363 }
10366 }
10369 }
10371 tweak:
10373 /* Extension: If the worst conversion for one candidate is worse than the
10374 worst conversion for the other, take the first. */
10376 {
10381 {
10386 }
10392 {
10393 /* Don't choose a deleted function over ambiguity. */
10397 {
10399 "ISO C++ says that these are ambiguous, even "
10400 "though the worst conversion for the first is better than "
10404 }
10405 else
10408 }
10409 }
10413 }
10415 /* Given a list of candidates for overloading, find the best one, if any.
10416 This algorithm has a worst case of O(2n) (winner is last), and a best
10417 case of O(n/2) (totally ambiguous); much better than a sorting
10418 algorithm. */
10422 {
10427 /* Walk through the list once, comparing each current champ to the next
10428 candidate, knocking out a candidate or two with each comparison. */
10431 {
10435 else
10436 {
10438 {
10443 }
10444 else
10445 {
10448 }
10451 }
10452 }
10454 /* Make sure the champ is better than all the candidates it hasn't yet
10455 been compared to. */
10458 challenger != champ
10461 {
10465 }
10468 }
10470 /* Returns nonzero if things of type FROM can be converted to TO. */
10472 bool
10474 {
10476 /* implicit_conversion only considers user-defined conversions
10477 if it has an expression for the call argument list. */
10481 }
10483 /* Returns nonzero if things of type FROM can be converted to TO with a
10484 standard conversion. */
10486 bool
10488 {
10490 }
10492 /* Returns nonzero if ARG (of type FROM) can be converted to TO. */
10494 bool
10496 tsubst_flags_t complain)
10497 {
10502 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10504 /* We want to discard any access checks done for this test,
10505 as we might not be in the appropriate access context and
10506 we'll do the check again when we actually perform the
10507 conversion. */
10514 /* Discard the access checks now. */
10516 /* Free all the conversions we allocated. */
10520 }
10522 /* Like can_convert_arg, but allows dubious conversions as well. */
10524 bool
10526 tsubst_flags_t complain)
10527 {
10531 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10533 /* Try to perform the conversion. */
10536 /* Free all the conversions we allocated. */
10540 }
10542 /* Convert EXPR to TYPE. Return the converted expression.
10544 Note that we allow bad conversions here because by the time we get to
10545 this point we are committed to doing the conversion. If we end up
10546 doing a bad conversion, convert_like will complain. */
10548 tree
10551 {
10558 else
10564 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10572 {
10574 {
10575 /* If expr has unknown type, then it is an overloaded function.
10576 Call instantiate_type to get good error messages. */
10581 else
10584 }
10586 }
10588 {
10589 /* In a template, we are only concerned about determining the
10590 type of non-dependent expressions, so we do not have to
10591 perform the actual conversion. But for initializers, we
10592 need to be able to perform it at instantiation
10593 (or instantiate_non_dependent_expr) time. */
10597 }
10598 else
10601 /* Free all the conversions we allocated. */
10605 }
10607 tree
10609 {
10611 LOOKUP_IMPLICIT);
10612 }
10614 /* Convert EXPR to TYPE (as a direct-initialization) if that is
10615 permitted. If the conversion is valid, the converted expression is
10616 returned. Otherwise, NULL_TREE is returned, except in the case
10617 that TYPE is a class type; in that case, an error is issued. If
10618 C_CAST_P is true, then this direct-initialization is taking
10619 place as part of a static_cast being attempted as part of a C-style
10620 cast. */
10622 tree
10624 tree expr,
10626 tsubst_flags_t complain)
10627 {
10633 /* [dcl.init]
10635 If the destination type is a (possibly cv-qualified) class type:
10637 -- If the initialization is direct-initialization ...,
10638 constructors are considered. ... If no constructor applies, or
10639 the overload resolution is ambiguous, the initialization is
10640 ill-formed. */
10642 {
10648 }
10650 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10654 c_cast_p,
10659 {
10660 /* In a template, we are only concerned about determining the
10661 type of non-dependent expressions, so we do not have to
10662 perform the actual conversion. But for initializers, we
10663 need to be able to perform it at instantiation
10664 (or instantiate_non_dependent_expr) time. */
10667 }
10668 else
10671 c_cast_p,
10672 complain);
10674 /* Free all the conversions we allocated. */
10678 }
10680 /* When initializing a reference that lasts longer than a full-expression,
10681 this special rule applies:
10683 [class.temporary]
10685 The temporary to which the reference is bound or the temporary
10686 that is the complete object to which the reference is bound
10687 persists for the lifetime of the reference.
10689 The temporaries created during the evaluation of the expression
10690 initializing the reference, except the temporary to which the
10691 reference is bound, are destroyed at the end of the
10692 full-expression in which they are created.
10694 In that case, we store the converted expression into a new
10695 VAR_DECL in a new scope.
10697 However, we want to be careful not to create temporaries when
10698 they are not required. For example, given:
10700 struct B {};
10701 struct D : public B {};
10702 D f();
10703 const B& b = f();
10705 there is no need to copy the return value from "f"; we can just
10706 extend its lifetime. Similarly, given:
10708 struct S {};
10709 struct T { operator S(); };
10710 T t;
10711 const S& s = t;
10713 we can extend the lifetime of the return value of the conversion
10714 operator.
10716 The next several functions are involved in this lifetime extension. */
10718 /* DECL is a VAR_DECL or FIELD_DECL whose type is a REFERENCE_TYPE. The
10719 reference is being bound to a temporary. Create and return a new
10720 VAR_DECL with the indicated TYPE; this variable will store the value to
10721 which the reference is bound. */
10723 tree
10725 {
10728 /* Register the variable. */
10731 {
10732 /* Namespace-scope or local static; give it a mangled name. */
10733 /* FIXME share comdat with decl? */
10744 }
10745 else
10746 /* Create a new cleanup level if necessary. */
10750 }
10752 /* EXPR is the initializer for a variable DECL of reference or
10753 std::initializer_list type. Create, push and return a new VAR_DECL
10754 for the initializer so that it will live as long as DECL. Any
10755 cleanup for the new variable is returned through CLEANUP, and the
10756 code to initialize the new variable is returned through INITP. */
10758 static tree
10761 {
10762 tree init;
10763 tree type;
10764 tree var;
10766 /* Create the temporary variable. */
10770 /* If the rvalue is the result of a function call it will be
10771 a TARGET_EXPR. If it is some other construct (such as a
10772 member access expression where the underlying object is
10773 itself the result of a function call), turn it into a
10774 TARGET_EXPR here. It is important that EXPR be a
10775 TARGET_EXPR below since otherwise the INIT_EXPR will
10776 attempt to make a bitwise copy of EXPR to initialize
10777 VAR. */
10783 {
10787 }
10789 /* Recursively extend temps in this initializer. */
10793 /* Any reference temp has a non-trivial initializer. */
10796 /* If the initializer is constant, put it in DECL_INITIAL so we get
10797 static initialization and use in constant expressions. */
10800 {
10802 {
10803 /* 5.19 says that a constant expression can include an
10804 lvalue-rvalue conversion applied to "a glvalue of literal type
10805 that refers to a non-volatile temporary object initialized
10806 with a constant expression". Rather than try to communicate
10807 that this VAR_DECL is a temporary, just mark it constexpr.
10809 Currently this is only useful for initializer_list temporaries,
10810 since reference vars can't appear in constant expressions. */
10814 }
10817 }
10818 else
10819 /* Create the INIT_EXPR that will initialize the temporary
10820 variable. */
10823 {
10828 else
10829 {
10833 }
10835 /* We must be careful to destroy the temporary only
10836 after its initialization has taken place. If the
10837 initialization throws an exception, then the
10838 destructor should not be run. We cannot simply
10839 transform INIT into something like:
10841 (INIT, ({ CLEANUP_STMT; }))
10843 because emit_local_var always treats the
10844 initializer as a full-expression. Thus, the
10845 destructor would run too early; it would run at the
10846 end of initializing the reference variable, rather
10847 than at the end of the block enclosing the
10848 reference variable.
10850 The solution is to pass back a cleanup expression
10851 which the caller is responsible for attaching to
10852 the statement tree. */
10853 }
10854 else
10855 {
10858 {
10861 tls_aggregates);
10862 else
10864 static_aggregates);
10865 }
10866 else
10867 /* Check whether the dtor is callable. */
10869 }
10870 /* Avoid -Wunused-variable warning (c++/38958). */
10877 }
10879 /* Convert EXPR to the indicated reference TYPE, in a way suitable for
10880 initializing a variable of that TYPE. */
10882 tree
10885 {
10893 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10899 {
10901 {
10910 else
10914 }
10916 }
10919 /* Perform the conversion. */
10922 /* We gave an error in build_user_type_conversion_1. */
10924 else
10927 /* Free all the conversions we allocated. */
10931 }
10933 /* Subroutine of extend_ref_init_temps. Possibly extend one initializer,
10934 which is bound either to a reference or a std::initializer_list. */
10936 static tree
10938 {
10943 {
10947 }
10950 /* Deal with binding to a subobject. */
10954 {
10962 }
10964 }
10966 /* INIT is part of the initializer for DECL. If there are any
10967 reference or initializer lists being initialized, extend their
10968 lifetime to match that of DECL. */
10970 tree
10972 {
10978 else
10979 {
10984 {
10986 {
10987 /* The temporary array underlying a std::initializer_list
10988 is handled like a reference temporary. */
10992 }
10993 else
10994 {
11000 }
11004 }
11005 }
11008 }
11010 /* Returns true iff an initializer for TYPE could contain temporaries that
11011 need to be extended because they are bound to references or
11012 std::initializer_list. */
11014 bool
11016 {
11021 {
11028 }
11030 }
11032 /* Returns true iff TYPE is some variant of std::initializer_list. */
11034 bool
11036 {
11041 /* Look through typedefs. */
11046 }
11048 /* Returns true iff DECL is a list constructor: i.e. a constructor which
11049 will accept an argument list of a single std::initializer_list<T>. */
11051 bool
11053 {
11055 tree arg;
11067 /* There are more non-defaulted parms. */
11071 }