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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. */
46 /* The various kinds of conversion. */
49 ck_identity,
50 ck_lvalue,
51 ck_fnptr,
52 ck_qual,
53 ck_std,
54 ck_ptr,
55 ck_pmem,
56 ck_base,
57 ck_ref_bind,
58 ck_user,
59 ck_ambig,
60 ck_list,
61 ck_aggr,
62 ck_rvalue
63 };
65 /* The rank of the conversion. Order of the enumerals matters; better
66 conversions should come earlier in the list. */
69 cr_identity,
70 cr_exact,
71 cr_promotion,
72 cr_std,
73 cr_pbool,
74 cr_user,
75 cr_ellipsis,
76 cr_bad
77 };
79 /* An implicit conversion sequence, in the sense of [over.best.ics].
80 The first conversion to be performed is at the end of the chain.
81 That conversion is always a cr_identity conversion. */
84 /* The kind of conversion represented by this step. */
85 conversion_kind kind;
86 /* The rank of this conversion. */
87 conversion_rank rank;
91 /* True if this conversion would be permitted with a bending of
92 language standards, e.g. disregarding pointer qualifiers or
93 converting integers to pointers. */
95 /* If KIND is ck_ref_bind ck_base_conv, true to indicate that a
96 temporary should be created to hold the result of the
97 conversion. If KIND is ck_ambig, true if the context is
98 copy-initialization. */
100 /* If KIND is ck_ptr or ck_pmem, true to indicate that a conversion
101 from a pointer-to-derived to pointer-to-base is being performed. */
103 /* If KIND is ck_ref_bind, true when either an lvalue reference is
104 being bound to an lvalue expression or an rvalue reference is
105 being bound to an rvalue expression. If KIND is ck_rvalue,
106 true when we are treating an lvalue as an rvalue (12.8p33). If
107 KIND is ck_base, always false. If ck_identity, we will be
108 binding a reference directly or decaying to a pointer. */
111 /* Whether check_narrowing should only check TREE_CONSTANTs; used
112 in build_converted_constant_expr. */
114 /* The type of the expression resulting from the conversion. */
115 tree type;
117 /* The next conversion in the chain. Since the conversions are
118 arranged from outermost to innermost, the NEXT conversion will
119 actually be performed before this conversion. This variant is
120 used only when KIND is neither ck_identity, ck_ambig nor
121 ck_list. Please use the next_conversion function instead
122 of using this field directly. */
124 /* The expression at the beginning of the conversion chain. This
125 variant is used only if KIND is ck_identity or ck_ambig. */
126 tree expr;
127 /* The array of conversions for an initializer_list, so this
128 variant is used only when KIN D is ck_list. */
131 /* The function candidate corresponding to this conversion
132 sequence. This field is only used if KIND is ck_user. */
134 };
136 #define CONVERSION_RANK(NODE) \
137 ((NODE)->bad_p ? cr_bad \
138 : (NODE)->ellipsis_p ? cr_ellipsis \
139 : (NODE)->user_conv_p ? cr_user \
140 : (NODE)->rank)
142 #define BAD_CONVERSION_RANK(NODE) \
143 ((NODE)->ellipsis_p ? cr_ellipsis \
144 : (NODE)->user_conv_p ? cr_user \
145 : (NODE)->rank)
154 tsubst_flags_t);
159 #define convert_like(CONV, EXPR, COMPLAIN) \
160 convert_like_real ((CONV), (EXPR), NULL_TREE, 0, \
163 #define convert_like_with_context(CONV, EXPR, FN, ARGNO, COMPLAIN ) \
164 convert_like_real ((CONV), (EXPR), (FN), (ARGNO), \
172 tsubst_flags_t);
184 static void add_builtin_candidates
187 static void add_builtin_candidate
191 static void build_builtin_candidate
201 tsubst_flags_t);
203 tsubst_flags_t);
223 tsubst_flags_t);
227 /* Returns nonzero iff the destructor name specified in NAME matches BASETYPE.
228 NAME can take many forms... */
230 bool
232 {
233 /* Just accept something we've already complained about. */
242 {
247 else
249 }
250 else
251 {
252 /* In the case of:
254 template <class T> struct S { ~S(); };
255 int i;
256 i.~S();
258 NAME will be a class template. */
261 }
266 }
268 /* We want the address of a function or method. We avoid creating a
269 pointer-to-member function. */
271 tree
273 {
276 /* We have to do these by hand to avoid real pointer to member
277 functions. */
279 {
281 {
285 complain);
286 }
288 }
289 else
293 }
295 /* Build a CALL_EXPR, we can handle FUNCTION_TYPEs, METHOD_TYPEs, or
296 POINTER_TYPE to those. Note, pointer to member function types
297 (TYPE_PTRMEMFUNC_P) must be handled by our callers. There are
298 two variants. build_call_a is the primitive taking an array of
299 arguments, while build_call_n is a wrapper that handles varargs. */
301 tree
303 {
306 else
307 {
317 }
318 }
320 /* Update various flags in cfun and the call itself based on what is being
321 called. Split out of build_call_a so that bot_manip can use it too. */
323 void
325 {
326 /* Handle both CALL_EXPRs and AGGR_INIT_EXPRs. */
329 /* We check both the decl and the type; a function may be known not to
330 throw without being declared throw(). */
346 }
348 tree
350 {
351 tree decl;
352 tree result_type;
353 tree fntype;
363 /* An rvalue has no cv-qualifiers. */
374 {
375 /* We invoke build_call directly for several library
376 functions. These may have been declared normally if
377 we're building libgcc, so we can't just check
378 DECL_ARTIFICIAL. */
383 }
389 /* Don't pass empty class objects by value. This is useful
390 for tags in STL, which are used to control overload resolution.
391 We don't need to handle other cases of copying empty classes. */
394 {
398 {
402 }
403 }
406 }
408 /* New overloading code. */
415 };
417 /* Information for providing diagnostics about why overloading failed. */
420 rr_none,
421 rr_arity,
422 rr_explicit_conversion,
423 rr_template_conversion,
424 rr_arg_conversion,
425 rr_bad_arg_conversion,
426 rr_template_unification,
427 rr_invalid_copy,
428 rr_inherited_ctor,
429 rr_constraint_failure
430 };
433 /* The index of the argument, 0-based. */
435 /* The actual argument or its type. */
436 tree from;
437 /* The type of the parameter. */
438 tree to_type;
439 };
444 /* Information about an arity mismatch. */
446 /* The expected number of arguments. */
448 /* The actual number of arguments in the call. */
450 /* Whether the call was a varargs call. */
453 /* Information about an argument conversion mismatch. */
455 /* Same, but for bad argument conversions. */
457 /* Information about template unification failures. These are the
458 parameters passed to fn_type_unification. */
460 tree tmpl;
461 tree explicit_targs;
465 tree return_type;
466 unification_kind_t strict;
469 /* Information about template instantiation failures. These are the
470 parameters passed to instantiate_template. */
472 tree tmpl;
473 tree targs;
476 };
479 /* The FUNCTION_DECL that will be called if this candidate is
480 selected by overload resolution. */
481 tree fn;
482 /* If not NULL_TREE, the first argument to use when calling this
483 function. */
484 tree first_arg;
485 /* The rest of the arguments to use when calling this function. If
486 there are no further arguments this may be NULL or it may be an
487 empty vector. */
489 /* The implicit conversion sequences for each of the arguments to
490 FN. */
492 /* The number of implicit conversion sequences. */
494 /* If FN is a user-defined conversion, the standard conversion
495 sequence from the type returned by FN to the desired destination
496 type. */
499 /* If FN is a member function, the binfo indicating the path used to
500 qualify the name of FN at the call site. This path is used to
501 determine whether or not FN is accessible if it is selected by
502 overload resolution. The DECL_CONTEXT of FN will always be a
503 (possibly improper) base of this binfo. */
504 tree access_path;
505 /* If FN is a non-static member function, the binfo indicating the
506 subobject to which the `this' pointer should be converted if FN
507 is selected by overload resolution. The type pointed to by
508 the `this' pointer must correspond to the most derived class
509 indicated by the CONVERSION_PATH. */
510 tree conversion_path;
511 tree template_decl;
512 tree explicit_targs;
517 /* The flags active in add_candidate. */
519 };
521 /* Returns true iff T is a null pointer constant in the sense of
522 [conv.ptr]. */
524 bool
526 {
529 /* [conv.ptr]
531 A null pointer constant is an integral constant expression
532 (_expr.const_) rvalue of integer type that evaluates to zero or
533 an rvalue of type std::nullptr_t. */
538 {
541 /* Core issue 903 says only literal 0 is a null pointer constant. */
548 }
550 {
555 }
558 }
560 /* Returns true iff T is a null member pointer value (4.11). */
562 bool
564 {
573 else
575 }
577 /* Returns nonzero if PARMLIST consists of only default parms,
578 ellipsis, and/or undeduced parameter packs. */
580 bool
582 {
589 }
591 /* Allocate N bytes of memory from the conversion obstack. The memory
592 is zeroed before being returned. */
596 {
599 {
602 }
606 }
608 /* Allocate rejection reasons. */
612 {
617 }
621 {
627 }
631 {
638 }
642 {
649 }
653 {
659 }
663 {
669 }
676 {
683 /* Copy args to our own storage. */
691 }
695 {
697 }
701 {
704 }
708 {
711 }
713 // Build a constraint failure record, saving information into the
714 // template_instantiation field of the rejection. If FN is not a template
715 // declaration, the TMPL member is the FN declaration and TARGS is empty.
719 {
722 {
725 }
726 else
727 {
730 }
732 }
734 /* Dynamically allocate a conversion. */
738 {
743 }
745 /* Make sure that all memory on the conversion obstack has been
746 freed. */
748 void
750 {
754 }
756 /* Dynamically allocate an array of N conversions. */
760 {
762 }
766 {
770 /* Note that the caller is responsible for filling in t->cand for
771 user-defined conversions. */
777 {
794 }
800 }
802 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
803 specialization of std::initializer_list<T>, if such a conversion is
804 possible. */
808 {
814 tree val;
816 /* Within a list-initialization we can have more user-defined
817 conversions. */
819 /* But no narrowing conversions. */
822 /* Can't make an array of these types. */
829 {
830 conversion *sub
837 }
845 {
853 }
856 }
858 /* Return the next conversion of the conversion chain (if applicable),
859 or NULL otherwise. Please use this function instead of directly
860 accessing fields of struct conversion. */
864 {
871 }
873 /* Subroutine of build_aggr_conv: check whether CTOR, a braced-init-list,
874 is a valid aggregate initializer for array type ATYPE. */
876 static bool
878 {
882 {
888 else
890 complain);
893 }
895 }
897 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
898 aggregate class, if such a conversion is possible. */
902 {
908 /* We already called reshape_init in implicit_conversion. */
910 /* The conversions within the init-list aren't affected by the enclosing
911 context; they're always simple copy-initialization. */
915 {
917 tree val;
925 /* Value-initialization of reference is ill-formed. */
927 else
928 {
932 }
938 else
940 complain);
947 }
959 }
961 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
962 array type, if such a conversion is possible. */
966 {
971 tree val;
976 /* We might need to propagate the size from the element to the array. */
981 {
985 }
990 {
991 conversion *sub
1003 }
1012 }
1014 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
1015 complex type, if such a conversion is possible. */
1019 tsubst_flags_t complain)
1020 {
1025 tree val;
1036 {
1037 conversion *sub
1049 }
1058 }
1060 /* Build a representation of the identity conversion from EXPR to
1061 itself. The TYPE should match the type of EXPR, if EXPR is non-NULL. */
1065 {
1073 }
1075 /* Converting from EXPR to TYPE was ambiguous in the sense that there
1076 were multiple user-defined conversions to accomplish the job.
1077 Build a conversion that indicates that ambiguity. */
1081 {
1089 }
1091 tree
1093 {
1097 }
1099 /* Returns the standard conversion path (see [conv]) from type FROM to type
1100 TO, if any. For proper handling of null pointer constants, you must
1101 also pass the expression EXPR to convert from. If C_CAST_P is true,
1102 this conversion is coming from a C-style cast. */
1107 {
1111 tree qualified_to;
1115 {
1118 }
1124 {
1126 {
1132 }
1134 {
1135 /* Necessary for eg, TEMPLATE_ID_EXPRs (c++/50961). */
1138 }
1139 }
1146 {
1149 /* Tell convert_like_real that we're using the address. */
1152 }
1153 /* Wrapping a ck_rvalue around a class prvalue (as a result of using
1154 obvalue_p) seems odd, since it's already a prvalue, but that's how we
1155 express the copy constructor call required by copy-initialization. */
1157 {
1159 {
1160 tree bitfield_type;
1163 {
1166 }
1167 }
1170 /* Tell convert_like_real to set LOOKUP_PREFER_RVALUE. */
1172 }
1174 /* Allow conversion between `__complex__' data types. */
1176 {
1177 /* The standard conversion sequence to convert FROM to TO is
1178 the standard conversion sequence to perform componentwise
1179 conversion. */
1182 complain);
1185 {
1188 }
1189 else
1193 }
1196 {
1200 }
1202 /* [conv.ptr]
1203 A null pointer constant can be converted to a pointer type; ... A
1204 null pointer constant of integral type can be converted to an
1205 rvalue of type std::nullptr_t. */
1213 {
1214 /* For backwards brain damage compatibility, allow interconversion of
1215 pointers and integers with a pedwarn. */
1218 }
1220 {
1221 /* For backwards brain damage compatibility, allow interconversion of
1222 enums and integers with a pedwarn. */
1225 }
1228 {
1229 tree to_pointee;
1230 tree from_pointee;
1233 {
1237 /* Since this is the target of a pointer, it can't have function
1238 qualifiers, so any TYPE_QUALS must be for attributes const or
1239 noreturn. Strip them. */
1246 }
1247 else
1248 {
1251 }
1255 to_pointee))
1256 ;
1260 {
1262 /* Don't try to apply restrict to void. */
1267 }
1269 {
1276 && (same_type_ignoring_top_level_qualifiers_p
1278 {
1281 }
1282 else
1284 }
1287 /* [conv.ptr]
1289 An rvalue of type "pointer to cv D," where D is a
1290 class type, can be converted to an rvalue of type
1291 "pointer to cv B," where B is a base class (clause
1292 _class.derived_) of D. If B is an inaccessible
1293 (clause _class.access_) or ambiguous
1294 (_class.member.lookup_) base class of D, a program
1295 that necessitates this conversion is ill-formed.
1296 Therefore, we use DERIVED_FROM_P, and do not check
1297 access or uniqueness. */
1299 {
1300 from_pointee
1306 }
1311 /* In a C-style cast, we ignore CV-qualification because we
1312 are allowed to perform a static_cast followed by a
1313 const_cast. */
1318 /* converting from string constant to char *. */
1322 /* Allow conversions among compatible ObjC pointer types (base
1323 conversions have been already handled above). */
1328 {
1331 }
1332 else
1336 }
1338 {
1352 else
1356 {
1358 tbase,
1364 }
1367 }
1369 {
1370 /* [conv.bool]
1372 A prvalue of arithmetic, unscoped enumeration, pointer, or pointer
1373 to member type can be converted to a prvalue of type bool. ...
1374 For direct-initialization (8.5 [dcl.init]), a prvalue of type
1375 std::nullptr_t can be converted to a prvalue of type bool; */
1381 {
1394 }
1397 }
1398 /* We don't check for ENUMERAL_TYPE here because there are no standard
1399 conversions to enum type. */
1400 /* As an extension, allow conversion to complex type. */
1402 {
1409 /* Give this a better rank if it's a promotion. */
1413 }
1419 {
1423 /* The derived-to-base conversion indicates the initialization
1424 of a parameter with base type from an object of a derived
1425 type. A temporary object is created to hold the result of
1426 the conversion unless we're binding directly to a reference. */
1428 }
1429 else
1436 }
1438 /* Returns nonzero if T1 is reference-related to T2. */
1440 bool
1442 {
1449 /* [dcl.init.ref]
1451 Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
1452 to "cv2 T2" if T1 is the same type as T2, or T1 is a base class
1453 of T2. */
1457 }
1459 /* Returns nonzero if T1 is reference-compatible with T2. */
1461 static bool
1463 {
1464 /* [dcl.init.ref]
1466 "cv1 T1" is reference compatible with "cv2 T2" if
1467 * T1 is reference-related to T2 or
1468 * T2 is "noexcept function" and T1 is "function", where the
1469 function types are otherwise the same,
1470 and cv1 is the same cv-qualification as, or greater cv-qualification
1471 than, cv2. */
1475 }
1477 /* A reference of the indicated TYPE is being bound directly to the
1478 expression represented by the implicit conversion sequence CONV.
1479 Return a conversion sequence for this binding. */
1483 {
1484 tree t;
1492 /* Mark the identity conv as to not decay to rvalue. */
1495 /* [over.ics.rank]
1497 When a parameter of reference type binds directly
1498 (_dcl.init.ref_) to an argument expression, the implicit
1499 conversion sequence is the identity conversion, unless the
1500 argument expression has a type that is a derived class of the
1501 parameter type, in which case the implicit conversion sequence is
1502 a derived-to-base Conversion.
1504 If the parameter binds directly to the result of applying a
1505 conversion function to the argument expression, the implicit
1506 conversion sequence is a user-defined conversion sequence
1507 (_over.ics.user_), with the second standard conversion sequence
1508 either an identity conversion or, if the conversion function
1509 returns an entity of a type that is a derived class of the
1510 parameter type, a derived-to-base conversion. */
1512 {
1513 /* Represent the derived-to-base conversion. */
1515 /* We will actually be binding to the base-class subobject in
1516 the derived class, so we mark this conversion appropriately.
1517 That way, convert_like knows not to generate a temporary. */
1519 }
1522 }
1524 /* Returns the conversion path from type FROM to reference type TO for
1525 purposes of reference binding. For lvalue binding, either pass a
1526 reference type to FROM or an lvalue expression to EXPR. If the
1527 reference will be bound to a temporary, NEED_TEMPORARY_P is set for
1528 the conversion returned. If C_CAST_P is true, this
1529 conversion is coming from a C-style cast. */
1533 tsubst_flags_t complain)
1534 {
1538 tree tfrom;
1541 cp_lvalue_kind gl_kind;
1545 {
1550 }
1553 {
1555 /* DR 1288: Otherwise, if the initializer list has a single element
1556 of type E and ... [T's] referenced type is reference-related to E,
1557 the object or reference is initialized from that element... */
1559 {
1565 {
1569 }
1570 }
1571 /* Otherwise, if T is a reference type, a prvalue temporary of the type
1572 referenced by T is copy-list-initialized, and the reference is bound
1573 to that temporary. */
1575 skip:;
1576 }
1579 {
1584 else
1586 }
1592 else
1595 /* Don't allow a class prvalue when LOOKUP_NO_TEMP_BIND. */
1600 /* Same mask as real_lvalue_p. */
1607 /* Figure out whether or not the types are reference-related and
1608 reference compatible. We have to do this after stripping
1609 references from FROM. */
1611 /* If this is a C cast, first convert to an appropriately qualified
1612 type, so that we can later do a const_cast to the desired type. */
1618 /* Directly bind reference when target expression's type is compatible with
1619 the reference and expression is an lvalue. In DR391, the wording in
1620 [8.5.3/5 dcl.init.ref] is changed to also require direct bindings for
1621 const and rvalue references to rvalues of compatible class type.
1622 We should also do direct bindings for non-class xvalues. */
1624 {
1625 /* [dcl.init.ref]
1627 If the initializer expression
1629 -- is an lvalue (but not an lvalue for a bit-field), and "cv1 T1"
1630 is reference-compatible with "cv2 T2,"
1632 the reference is bound directly to the initializer expression
1633 lvalue.
1635 [...]
1636 If the initializer expression is an rvalue, with T2 a class type,
1637 and "cv1 T1" is reference-compatible with "cv2 T2", the reference
1638 is bound to the object represented by the rvalue or to a sub-object
1639 within that object. */
1645 /* Handle rvalue reference to function properly. */
1646 conv->rvaluedness_matches_p
1648 else
1649 conv->rvaluedness_matches_p
1654 /* For the purposes of overload resolution, we ignore the fact
1655 this expression is a bitfield or packed field. (In particular,
1656 [over.ics.ref] says specifically that a function with a
1657 non-const reference parameter is viable even if the
1658 argument is a bitfield.)
1660 However, when we actually call the function we must create
1661 a temporary to which to bind the reference. If the
1662 reference is volatile, or isn't const, then we cannot make
1663 a temporary, so we just issue an error when the conversion
1664 actually occurs. */
1667 /* Don't allow binding of lvalues (other than function lvalues) to
1668 rvalue references. */
1673 /* Nor the reverse. */
1684 }
1685 /* [class.conv.fct] A conversion function is never used to convert a
1686 (possibly cv-qualified) object to the (possibly cv-qualified) same
1687 object type (or a reference to it), to a (possibly cv-qualified) base
1688 class of that type (or a reference to it).... */
1691 {
1692 /* [dcl.init.ref]
1694 If the initializer expression
1696 -- has a class type (i.e., T2 is a class type) can be
1697 implicitly converted to an lvalue of type "cv3 T3," where
1698 "cv1 T1" is reference-compatible with "cv3 T3". (this
1699 conversion is selected by enumerating the applicable
1700 conversion functions (_over.match.ref_) and choosing the
1701 best one through overload resolution. (_over.match_).
1703 the reference is bound to the lvalue result of the conversion
1704 in the second case. */
1706 complain);
1709 }
1711 /* From this point on, we conceptually need temporaries, even if we
1712 elide them. Only the cases above are "direct bindings". */
1716 /* [over.ics.rank]
1718 When a parameter of reference type is not bound directly to an
1719 argument expression, the conversion sequence is the one required
1720 to convert the argument expression to the underlying type of the
1721 reference according to _over.best.ics_. Conceptually, this
1722 conversion sequence corresponds to copy-initializing a temporary
1723 of the underlying type with the argument expression. Any
1724 difference in top-level cv-qualification is subsumed by the
1725 initialization itself and does not constitute a conversion. */
1727 /* [dcl.init.ref]
1729 Otherwise, the reference shall be an lvalue reference to a
1730 non-volatile const type, or the reference shall be an rvalue
1731 reference.
1733 We try below to treat this as a bad conversion to improve diagnostics,
1734 but if TO is an incomplete class, we need to reject this conversion
1735 now to avoid unnecessary instantiation. */
1740 /* We're generating a temporary now, but don't bind any more in the
1741 conversion (specifically, don't slice the temporary returned by a
1742 conversion operator). */
1745 /* Core issue 899: When [copy-]initializing a temporary to be bound
1746 to the first parameter of a copy constructor (12.8) called with
1747 a single argument in the context of direct-initialization,
1748 explicit conversion functions are also considered.
1750 So don't set LOOKUP_ONLYCONVERTING in that case. */
1761 {
1762 /* If initializing the temporary used a conversion function,
1763 recalculate the second conversion sequence. */
1767 {
1770 conversion *new_second
1776 }
1777 }
1780 /* This reference binding, unlike those above, requires the
1781 creation of a temporary. */
1785 /* [dcl.init.ref]
1787 Otherwise, the reference shall be an lvalue reference to a
1788 non-volatile const type, or the reference shall be an rvalue
1789 reference. */
1793 /* [dcl.init.ref]
1795 Otherwise, a temporary of type "cv1 T1" is created and
1796 initialized from the initializer expression using the rules for a
1797 non-reference copy initialization. If T1 is reference-related to
1798 T2, cv1 must be the same cv-qualification as, or greater
1799 cv-qualification than, cv2; otherwise, the program is ill-formed. */
1804 }
1806 /* Returns the implicit conversion sequence (see [over.ics]) from type
1807 FROM to type TO. The optional expression EXPR may affect the
1808 conversion. FLAGS are the usual overloading flags. If C_CAST_P is
1809 true, this conversion is coming from a C-style cast. */
1814 {
1821 /* Other flags only apply to the primary function in overload
1822 resolution, or after we've chosen one. */
1827 /* FIXME: actually we don't want warnings either, but we can't just
1828 have 'complain &= ~(tf_warning|tf_error)' because it would cause
1829 the regression of, eg, g++.old-deja/g++.benjamin/16077.C.
1830 We really ought not to issue that warning until we've committed
1831 to that conversion. */
1834 /* Call reshape_init early to remove redundant braces. */
1839 {
1844 }
1848 else
1855 {
1859 /* As an extension, allow list-initialization of _Complex. */
1861 {
1865 }
1867 /* Allow conversion from an initializer-list with one element to a
1868 scalar type. */
1870 {
1872 tree elt;
1878 else
1884 {
1887 /* Too many levels of braces, i.e. '{{1}}'. */
1890 }
1891 }
1894 }
1900 {
1910 {
1914 {
1915 /* "If C is not an initializer-list constructor and the
1916 initializer list has a single element of type cv U, where U is
1917 X or a class derived from X, the implicit conversion sequence
1918 has Exact Match rank if U is X, or Conversion rank if U is
1919 derived from X." */
1925 }
1927 }
1929 /* We used to try to bind a reference to a temporary here, but that
1930 is now handled after the recursive call to this function at the end
1931 of reference_binding. */
1933 }
1936 }
1938 /* Like implicit_conversion, but return NULL if the conversion is bad.
1940 This is not static so that check_non_deducible_conversion can call it within
1941 add_template_candidate_real as part of overload resolution; it should not be
1942 called outside of overload resolution. */
1944 conversion *
1947 {
1953 }
1955 /* Add a new entry to the list of candidates. Used by the add_*_candidate
1956 functions. ARGS will not be changed until a single candidate is
1957 selected. */
1966 {
1984 }
1986 /* Return the number of remaining arguments in the parameter list
1987 beginning with ARG. */
1989 int
1991 {
1996 n++;
1999 }
2001 /* [over.match.copy]: When initializing a temporary object (12.2) to be bound
2002 to the first parameter of a constructor where the parameter is of type
2003 "reference to possibly cv-qualified T" and the constructor is called with a
2004 single argument in the context of direct-initialization of an object of type
2005 "cv2 T", explicit conversion functions are also considered.
2007 So set LOOKUP_COPY_PARM to let reference_binding know that
2008 it's being called in that context. */
2010 int
2012 {
2014 tree t;
2017 && (same_type_ignoring_top_level_qualifiers_p
2019 {
2025 }
2026 else
2030 }
2032 /* Create an overload candidate for the function or method FN called
2033 with the argument list FIRST_ARG/ARGS and add it to CANDIDATES.
2034 FLAGS is passed on to implicit_conversion.
2036 This does not change ARGS.
2038 CTYPE, if non-NULL, is the type we want to pretend this function
2039 comes from for purposes of overload resolution. */
2047 tsubst_flags_t complain)
2048 {
2051 tree parmnode;
2057 /* At this point we should not see any functions which haven't been
2058 explicitly declared, except for friend functions which will have
2059 been found using argument dependent lookup. */
2062 /* The `this', `in_chrg' and VTT arguments to constructors are not
2063 considered in overload resolution. */
2065 {
2067 /* Bring back parameters omitted from an inherited ctor. */
2069 else
2073 {
2076 }
2077 }
2078 else
2085 /* 13.3.2 - Viable functions [over.match.viable]
2086 First, to be a viable function, a candidate function shall have enough
2087 parameters to agree in number with the arguments in the list.
2089 We need to check this first; otherwise, checking the ICSes might cause
2090 us to produce an ill-formed template instantiation. */
2094 {
2098 }
2102 {
2106 }
2108 /* An inherited constructor (12.6.3 [class.inhctor.init]) that has a first
2109 parameter of type "reference to cv C" (including such a constructor
2110 instantiated from a template) is excluded from the set of candidate
2111 functions when used to construct an object of type D with an argument list
2112 containing a single argument if C is reference-related to D. */
2114 && flag_new_inheriting_ctors
2116 {
2122 {
2125 }
2126 }
2128 /* Second, for a function to be viable, its constraints must be
2129 satisfied. */
2132 {
2135 }
2137 /* When looking for a function from a subobject from an implicit
2138 copy/move constructor/operator=, don't consider anything that takes (a
2139 reference to) an unrelated type. See c++/44909 and core 1092. */
2141 {
2147 else
2150 {
2153 ctype))
2155 }
2157 /* This only applies at the top level. */
2159 }
2164 /* Third, for F to be a viable function, there shall exist for each
2165 argument an implicit conversion sequence that converts that argument
2166 to the corresponding parameter of F. */
2171 {
2173 tree arg;
2181 {
2182 /* Already set during deduction. */
2185 }
2189 else
2198 {
2203 /* The type of the implicit object parameter ('this') for
2204 overload resolution is not always the same as for the
2205 function itself; conversion functions are considered to
2206 be members of the class being converted, and functions
2207 introduced by a using-declaration are considered to be
2208 members of the class that uses them.
2210 Since build_over_call ignores the ICS for the `this'
2211 parameter, we can just change the parm type. */
2213 {
2214 parmtype = cp_build_qualified_type
2217 {
2218 /* If the function has a ref-qualifier, the implicit
2219 object parameter has reference type. */
2222 /* The special handling of 'this' conversions in compare_ics
2223 does not apply if there is a ref-qualifier. */
2225 }
2226 else
2227 {
2229 /* We don't use build_this here because we don't want to
2230 capture the object argument until we've chosen a
2231 non-static member function. */
2234 }
2235 }
2242 }
2243 else
2244 {
2248 }
2255 {
2259 }
2262 {
2265 }
2266 }
2268 out:
2271 }
2273 /* Create an overload candidate for the conversion function FN which will
2274 be invoked for expression OBJ, producing a pointer-to-function which
2275 will in turn be called with the argument list FIRST_ARG/ARGLIST,
2276 and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
2277 passed on to implicit_conversion.
2279 Actually, we don't really care about FN; we care about the type it
2280 converts to. There may be multiple conversion functions that will
2281 convert to that type, and we rely on build_user_type_conversion_1 to
2282 choose the best one; so when we create our candidate, we record the type
2283 instead of the function. */
2289 tsubst_flags_t complain)
2290 {
2308 /* Don't bother looking up the same type twice. */
2313 {
2319 else
2324 {
2327 /* Leave the 'cand' field null; we'll figure out the conversion in
2328 convert_like_real if this candidate is chosen. */
2330 }
2334 {
2338 }
2339 else
2340 {
2344 }
2351 {
2354 }
2361 }
2365 {
2369 }
2373 }
2375 static void
2379 {
2393 /* TRUTH_*_EXPR do "contextual conversion to bool", which means explicit
2394 conversion ops are allowed. We handle that here by just checking for
2395 boolean_type_node because other operators don't ask for it. COND_EXPR
2396 also does contextual conversion to bool for the first operand, but we
2397 handle that in build_conditional_expr, and type1 here is operand 2. */
2402 {
2409 {
2411 /* We need something for printing the candidate. */
2415 }
2417 {
2421 }
2423 }
2425 /* For COND_EXPR we rearranged the arguments; undo that now. */
2427 {
2432 complain);
2435 else
2436 {
2439 boolean_type_node);
2440 }
2441 }
2448 }
2450 static bool
2452 {
2454 }
2456 /* Returns nonzero if TYPE is a promoted arithmetic type. */
2458 static bool
2460 {
2461 /* [over.built]
2463 In this section, the term promoted integral type is used to refer
2464 to those integral types which are preserved by integral promotion
2465 (including e.g. int and long but excluding e.g. char).
2466 Similarly, the term promoted arithmetic type refers to promoted
2467 integral types plus floating types. */
2471 }
2473 /* Create any builtin operator overload candidates for the operator in
2474 question given the converted operand types TYPE1 and TYPE2. The other
2475 args are passed through from add_builtin_candidates to
2476 build_builtin_candidate.
2478 TYPE1 and TYPE2 may not be permissible, and we must filter them.
2479 If CODE is requires candidates operands of the same type of the kind
2480 of which TYPE1 and TYPE2 are, we add both candidates
2481 CODE (TYPE1, TYPE1) and CODE (TYPE2, TYPE2). */
2483 static void
2487 tsubst_flags_t complain)
2488 {
2490 {
2498 }
2501 {
2503 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2504 and VQ is either volatile or empty, there exist candidate operator
2505 functions of the form
2506 VQ T& operator++(VQ T&);
2507 T operator++(VQ T&, int);
2508 5 For every pair T, VQ), where T is an enumeration type or an arithmetic
2509 type other than bool, and VQ is either volatile or empty, there exist
2510 candidate operator functions of the form
2511 VQ T& operator--(VQ T&);
2512 T operator--(VQ T&, int);
2513 6 For every pair T, VQ), where T is a cv-qualified or cv-unqualified
2514 complete object type, and VQ is either volatile or empty, there exist
2515 candidate operator functions of the form
2516 T*VQ& operator++(T*VQ&);
2517 T*VQ& operator--(T*VQ&);
2518 T* operator++(T*VQ&, int);
2519 T* operator--(T*VQ&, int); */
2525 /* FALLTHRU */
2529 {
2532 }
2535 /* 7 For every cv-qualified or cv-unqualified object type T, there
2536 exist candidate operator functions of the form
2538 T& operator*(T*);
2540 8 For every function type T, there exist candidate operator functions of
2541 the form
2542 T& operator*(T*); */
2551 /* 9 For every type T, there exist candidate operator functions of the form
2552 T* operator+(T*);
2554 10For every promoted arithmetic type T, there exist candidate operator
2555 functions of the form
2556 T operator+(T);
2557 T operator-(T); */
2562 /* FALLTHRU */
2568 /* 11For every promoted integral type T, there exist candidate operator
2569 functions of the form
2570 T operator~(T); */
2577 /* 12For every quintuple C1, C2, T, CV1, CV2), where C2 is a class type, C1
2578 is the same type as C2 or is a derived class of C2, T is a complete
2579 object type or a function type, and CV1 and CV2 are cv-qualifier-seqs,
2580 there exist candidate operator functions of the form
2581 CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
2582 where CV12 is the union of CV1 and CV2. */
2586 {
2594 }
2597 /* 13For every pair of promoted arithmetic types L and R, there exist can-
2598 didate operator functions of the form
2599 LR operator*(L, R);
2600 LR operator/(L, R);
2601 LR operator+(L, R);
2602 LR operator-(L, R);
2603 bool operator<(L, R);
2604 bool operator>(L, R);
2605 bool operator<=(L, R);
2606 bool operator>=(L, R);
2607 bool operator==(L, R);
2608 bool operator!=(L, R);
2609 where LR is the result of the usual arithmetic conversions between
2610 types L and R.
2612 14For every pair of types T and I, where T is a cv-qualified or cv-
2613 unqualified complete object type and I is a promoted integral type,
2614 there exist candidate operator functions of the form
2615 T* operator+(T*, I);
2616 T& operator[](T*, I);
2617 T* operator-(T*, I);
2618 T* operator+(I, T*);
2619 T& operator[](I, T*);
2621 15For every T, where T is a pointer to complete object type, there exist
2622 candidate operator functions of the form112)
2623 ptrdiff_t operator-(T, T);
2625 16For every pointer or enumeration type T, there exist candidate operator
2626 functions of the form
2627 bool operator<(T, T);
2628 bool operator>(T, T);
2629 bool operator<=(T, T);
2630 bool operator>=(T, T);
2631 bool operator==(T, T);
2632 bool operator!=(T, T);
2634 17For every pointer to member type T, there exist candidate operator
2635 functions of the form
2636 bool operator==(T, T);
2637 bool operator!=(T, T); */
2644 {
2647 }
2648 /* FALLTHRU */
2661 {
2664 }
2666 {
2669 }
2670 /* Fall through. */
2686 {
2689 }
2692 {
2695 }
2701 /* FALLTHRU */
2704 {
2707 }
2709 {
2712 }
2715 /* 18For every pair of promoted integral types L and R, there exist candi-
2716 date operator functions of the form
2717 LR operator%(L, R);
2718 LR operator&(L, R);
2719 LR operator^(L, R);
2720 LR operator|(L, R);
2721 L operator<<(L, R);
2722 L operator>>(L, R);
2723 where LR is the result of the usual arithmetic conversions between
2724 types L and R. */
2732 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2736 /* 19For every triple L, VQ, R), where L is an arithmetic or enumeration
2737 type, VQ is either volatile or empty, and R is a promoted arithmetic
2738 type, there exist candidate operator functions of the form
2739 VQ L& operator=(VQ L&, R);
2740 VQ L& operator*=(VQ L&, R);
2741 VQ L& operator/=(VQ L&, R);
2742 VQ L& operator+=(VQ L&, R);
2743 VQ L& operator-=(VQ L&, R);
2745 20For every pair T, VQ), where T is any type and VQ is either volatile
2746 or empty, there exist candidate operator functions of the form
2747 T*VQ& operator=(T*VQ&, T*);
2749 21For every pair T, VQ), where T is a pointer to member type and VQ is
2750 either volatile or empty, there exist candidate operator functions of
2751 the form
2752 VQ T& operator=(VQ T&, T);
2754 22For every triple T, VQ, I), where T is a cv-qualified or cv-
2755 unqualified complete object type, VQ is either volatile or empty, and
2756 I is a promoted integral type, there exist candidate operator func-
2757 tions of the form
2758 T*VQ& operator+=(T*VQ&, I);
2759 T*VQ& operator-=(T*VQ&, I);
2761 23For every triple L, VQ, R), where L is an integral or enumeration
2762 type, VQ is either volatile or empty, and R is a promoted integral
2763 type, there exist candidate operator functions of the form
2765 VQ L& operator%=(VQ L&, R);
2766 VQ L& operator<<=(VQ L&, R);
2767 VQ L& operator>>=(VQ L&, R);
2768 VQ L& operator&=(VQ L&, R);
2769 VQ L& operator^=(VQ L&, R);
2770 VQ L& operator|=(VQ L&, R); */
2774 {
2778 {
2781 }
2782 /* FALLTHRU */
2795 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2808 {
2811 }
2816 }
2821 /* [over.built]
2823 For every pair of promoted arithmetic types L and R, there
2824 exist candidate operator functions of the form
2826 LR operator?(bool, L, R);
2828 where LR is the result of the usual arithmetic conversions
2829 between types L and R.
2831 For every type T, where T is a pointer or pointer-to-member
2832 type, there exist candidate operator functions of the form T
2833 operator?(bool, T, T); */
2837 /* That's OK. */
2840 /* Otherwise, the types should be pointers. */
2844 /* We don't check that the two types are the same; the logic
2845 below will actually create two candidates; one in which both
2846 parameter types are TYPE1, and one in which both parameter
2847 types are TYPE2. */
2858 }
2860 /* Make sure we don't create builtin candidates with dependent types. */
2864 {
2865 /* Try to recover if one of the types is non-dependent. But if
2866 there's only one type, there's nothing we can do. */
2869 /* And we lose if both are dependent. */
2872 /* Or if they have different forms. */
2880 }
2882 /* If we're dealing with two pointer types or two enumeral types,
2883 we need candidates for both of them. */
2892 {
2894 {
2896 error_mark_node,
2897 error_mark_node,
2898 CPO_CONVERSION,
2899 tf_none);
2901 {
2902 build_builtin_candidate
2906 }
2907 }
2909 build_builtin_candidate
2911 build_builtin_candidate
2914 }
2916 build_builtin_candidate
2918 }
2920 tree
2922 {
2928 }
2930 /* There are three conditions of builtin candidates:
2932 1) bool-taking candidates. These are the same regardless of the input.
2933 2) pointer-pair taking candidates. These are generated for each type
2934 one of the input types converts to.
2935 3) arithmetic candidates. According to the standard, we should generate
2936 all of these, but I'm trying not to...
2938 Here we generate a superset of the possible candidates for this particular
2939 case. That is a subset of the full set the standard defines, plus some
2940 other cases which the standard disallows. add_builtin_candidate will
2941 filter out the invalid set. */
2943 static void
2947 {
2951 /* TYPES[i] is the set of possible builtin-operator parameter types
2952 we will consider for the Ith argument. */
2957 {
2960 else
2962 }
2965 {
2966 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2967 and VQ is either volatile or empty, there exist candidate operator
2968 functions of the form
2969 VQ T& operator++(VQ T&); */
2979 /* 24There also exist candidate operator functions of the form
2980 bool operator!(bool);
2981 bool operator&&(bool, bool);
2982 bool operator||(bool, bool); */
2985 build_builtin_candidate
2992 build_builtin_candidate
3010 /* Fall through. */
3014 }
3020 {
3022 ;
3024 {
3025 tree convs;
3033 {
3038 }
3044 {
3057 {
3063 }
3067 }
3068 }
3069 else
3070 {
3075 {
3081 }
3083 }
3084 }
3086 /* Run through the possible parameter types of both arguments,
3087 creating candidates with those parameter types. */
3089 {
3091 tree u;
3095 add_builtin_candidate
3098 else
3099 add_builtin_candidate
3102 }
3106 }
3109 /* If TMPL can be successfully instantiated as indicated by
3110 EXPLICIT_TARGS and ARGLIST, adds the instantiation to CANDIDATES.
3112 TMPL is the template. EXPLICIT_TARGS are any explicit template
3113 arguments. ARGLIST is the arguments provided at the call-site.
3114 This does not change ARGLIST. The RETURN_TYPE is the desired type
3115 for conversion operators. If OBJ is NULL_TREE, FLAGS and CTYPE are
3116 as for add_function_candidate. If an OBJ is supplied, FLAGS and
3117 CTYPE are ignored, and OBJ is as for add_conv_candidate. */
3125 tsubst_flags_t complain)
3126 {
3136 tree arg;
3138 tree fn;
3143 /* We don't do deduction on the in-charge parameter, the VTT
3144 parameter or 'this'. */
3146 {
3150 /* We're deducing for a call to the result of a template conversion
3152 else
3154 }
3159 {
3162 else
3164 }
3172 {
3173 /* 12.8/6 says, "A declaration of a constructor for a class X is
3174 ill-formed if its first parameter is of type (optionally cv-qualified)
3175 X and either there are no other parameters or else all other
3176 parameters have default arguments. A member function template is never
3177 instantiated to produce such a constructor signature."
3179 So if we're trying to copy an object of the containing class, don't
3180 consider a template constructor that has a first parameter type that
3181 is just a template parameter, as we would deduce a signature that we
3182 would then reject in the code below. */
3184 {
3189 {
3193 }
3194 }
3195 }
3202 {
3205 }
3209 {
3212 }
3219 args_without_in_chrg,
3220 nargs_without_in_chrg,
3225 {
3226 /* Don't repeat unification later if it already resulted in errors. */
3230 nargs_without_in_chrg,
3232 else
3235 }
3238 {
3241 ctype))
3242 {
3243 /* We're trying to produce a constructor with a prohibited signature,
3244 as discussed above; handle here any cases we didn't catch then,
3245 such as X(X<T>). */
3248 }
3249 }
3252 /* Aha, this is a conversion function. */
3255 else
3260 /* This situation can occur if a member template of a template
3261 class is specialized. Then, instantiate_template might return
3262 an instantiation of the specialization, in which case the
3263 DECL_TI_TEMPLATE field will point at the original
3264 specialization. For example:
3266 template <class T> struct S { template <class U> void f(U);
3267 template <> void f(int) {}; };
3268 S<double> sd;
3269 sd.f(3);
3271 Here, TMPL will be template <class U> S<double>::f(U).
3272 And, instantiate template will give us the specialization
3273 template <> S<double>::f(int). But, the DECL_TI_TEMPLATE field
3274 for this will point at template <class T> template <> S<T>::f(int),
3275 so that we can find the definition. For the purposes of
3276 overload resolution, however, we want the original TMPL. */
3278 else
3283 fail:
3286 }
3295 {
3296 return
3301 }
3303 /* Create an overload candidate for the conversion function template TMPL,
3304 returning RETURN_TYPE, which will be invoked for expression OBJ to produce a
3305 pointer-to-function which will in turn be called with the argument list
3306 ARGLIST, and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
3307 passed on to implicit_conversion. */
3311 tree obj,
3315 {
3316 /* Making this work broke PR 71117 and 85118, so until the committee resolves
3317 core issue 2189, let's disable this candidate if there are any call
3318 operators. */
3322 return
3326 complain);
3327 }
3329 /* The CANDS are the set of candidates that were considered for
3330 overload resolution. Return the set of viable candidates, or CANDS
3331 if none are viable. If any of the candidates were viable, set
3332 *ANY_VIABLE_P to true. STRICT_P is true if a candidate should be
3333 considered viable only if it is strictly viable. */
3339 {
3345 /* Be strict inside templates, since build_over_call won't actually
3346 do the conversions to get pedwarns. */
3356 {
3360 {
3361 /* Be strict in the presence of a viable candidate. Also if
3362 there are template candidates, so that we get deduction errors
3363 for them instead of silently preferring a bad conversion. */
3366 {
3367 /* Put any spliced near matches back onto the main list so
3368 that we see them if there is no strict match. */
3374 }
3375 }
3378 {
3386 }
3387 else
3389 }
3392 }
3394 static bool
3396 {
3401 }
3403 /* OBJ is being used in an expression like "OBJ.f (...)". In other
3404 words, it is about to become the "this" pointer for a member
3405 function call. Take the address of the object. */
3407 static tree
3409 {
3410 /* In a template, we are only concerned about the type of the
3411 expression, so we can take a shortcut. */
3416 }
3418 /* Returns true iff functions are equivalent. Equivalent functions are
3419 not '==' only if one is a function-local extern function or if
3420 both are extern "C". */
3424 {
3433 }
3435 /* Print information about a candidate being rejected due to INFO. */
3437 static void
3439 {
3444 {
3445 /* Conversion of implicit `this' argument failed. */
3447 /* A bad conversion for 'this' must be discarding cv-quals. */
3450 from);
3451 else
3455 }
3457 {
3462 tf_warning_or_error);
3463 }
3465 /* Conversion of conversion function return value failed. */
3468 else
3471 }
3473 /* Print information about a candidate with WANT parameters and we found
3474 HAVE. */
3476 static void
3478 {
3483 }
3485 /* Print information about one overload candidate CANDIDATE. MSGSTR
3486 is the text to print before the candidate itself.
3488 NOTE: Unlike most diagnostic functions in GCC, MSGSTR is expected
3489 to have been run through gettext by the caller. This wart makes
3490 life simpler in print_z_candidates and for the translators. */
3492 static void
3495 {
3505 {
3516 else
3519 }
3526 else
3529 {
3532 }
3533 /* Give the user some information about why this candidate failed. */
3535 {
3539 {
3552 "cannot be converted to %qT with a qualification "
3558 "conversion function specialization to %qT is not an "
3563 /* We use template_unification_error_rejection if unification caused
3564 actual non-SFINAE errors, in which case we don't need to repeat
3565 them here. */
3567 {
3571 }
3572 /* Re-run template unification with diagnostics. */
3576 (make_tree_vec
3587 " a constructor taking a single argument of its own "
3591 {
3595 }
3599 "initialization from an expression of the same or derived "
3604 /* This candidate didn't have any issues or we failed to
3605 handle a particular code. Either way... */
3607 }
3608 }
3609 }
3611 static void
3613 {
3620 /* Remove non-viable deleted candidates. */
3623 {
3628 else
3630 }
3631 /* ...if there are any non-deleted ones. */
3635 /* There may be duplicates in the set of candidates. We put off
3636 checking this condition as long as possible, since we have no way
3637 to eliminate duplicates from a set of functions in less than n^2
3638 time. Now we are about to emit an error message, so it is more
3639 permissible to go slowly. */
3641 {
3643 /* Skip builtin candidates and conversion functions. */
3648 {
3652 else
3654 }
3655 }
3659 }
3661 /* USER_SEQ is a user-defined conversion sequence, beginning with a
3662 USER_CONV. STD_SEQ is the standard conversion sequence applied to
3663 the result of the conversion function to convert it to the final
3664 desired type. Merge the two sequences into a single sequence,
3665 and return the merged sequence. */
3669 {
3675 /* Find the end of the second conversion sequence. */
3677 {
3678 /* The entire sequence is a user-conversion sequence. */
3682 }
3685 /* We're binding a reference directly to the result of the conversion.
3686 build_user_type_conversion_1 stripped the REFERENCE_TYPE from the return
3687 type, but we want it back. */
3690 /* Replace the identity conversion with the user conversion
3691 sequence. */
3695 }
3697 /* Handle overload resolution for initializing an object of class type from
3698 an initializer list. First we look for a suitable constructor that
3699 takes a std::initializer_list; if we don't find one, we then look for a
3700 non-list constructor.
3702 Parameters are as for add_candidates, except that the arguments are in
3703 the form of a CONSTRUCTOR (the initializer list) rather than a vector, and
3704 the RETURN_TYPE parameter is replaced by TOTYPE, the desired type. */
3706 static void
3713 tsubst_flags_t complain)
3714 {
3717 /* We're looking for a ctor for list-initialization. */
3719 /* And we don't allow narrowing conversions. We also use this flag to
3720 avoid the copy constructor call for copy-list-initialization. */
3726 /* Always use the default constructor if the list is empty (DR 990). */
3729 ;
3730 /* If the class has a list ctor, try passing the list as a single
3731 argument first, but only consider list ctors. */
3733 {
3740 }
3742 /* Expand the CONSTRUCTOR into a new argument vec. */
3750 /* We aren't looking for list-ctors anymore. */
3752 /* We allow more user-defined conversions within an init-list. */
3758 }
3760 /* Returns the best overload candidate to perform the requested
3761 conversion. This function is used for three the overloading situations
3762 described in [over.match.copy], [over.match.conv], and [over.match.ref].
3763 If TOTYPE is a REFERENCE_TYPE, we're trying to find a direct binding as
3764 per [dcl.init.ref], so we ignore temporary bindings. */
3768 tsubst_flags_t complain)
3769 {
3771 tree fromtype;
3785 /* We represent conversion within a hierarchy using RVALUE_CONV and
3786 BASE_CONV, as specified by [over.best.ics]; these become plain
3787 constructor calls, as specified in [dcl.init]. */
3792 /* Use lookup_fnfields_slot instead of lookup_fnfields to avoid
3793 creating a garbage BASELINK; constructors can't be inherited. */
3797 {
3802 {
3803 /* [class.conv.fct] A conversion function is never used to
3804 convert a (possibly cv-qualified) object to the (possibly
3805 cv-qualified) same object type (or a reference to it), to a
3806 (possibly cv-qualified) base class of that type (or a
3807 reference to it)... */
3808 }
3809 else
3811 }
3818 /* It's OK to bind a temporary for converting constructor arguments, but
3819 not in converting the return value of a conversion operator. */
3825 {
3830 /* We should never try to call the abstract or base constructor
3831 from here. */
3837 {
3838 /* List-initialization. */
3842 }
3843 else
3844 {
3848 }
3851 {
3854 /* If totype isn't a reference, and LOOKUP_NO_TEMP_BIND isn't
3855 set, then this is copy-initialization. In that case, "The
3856 result of the call is then used to direct-initialize the
3857 object that is the destination of the copy-initialization."
3858 [dcl.init]
3860 We represent this in the conversion sequence with an
3861 rvalue conversion, which means a constructor call. */
3864 cand->second_conv
3866 }
3867 }
3870 {
3873 else
3875 }
3878 {
3882 /* If we are called to convert to a reference type, we are trying to
3883 find a direct binding, so don't even consider temporaries. If
3884 we don't find a direct binding, the caller will try again to
3885 look for a temporary binding. */
3896 {
3898 conversion *ics
3900 rettype,
3903 complain);
3905 /* If LOOKUP_NO_TEMP_BIND isn't set, then this is
3906 copy-initialization. In that case, "The result of the
3907 call is then used to direct-initialize the object that is
3908 the destination of the copy-initialization." [dcl.init]
3910 We represent this in the conversion sequence with an
3911 rvalue conversion, which means a constructor call. But
3912 don't add a second rvalue conversion if there's already
3913 one there. Which there really shouldn't be, but it's
3914 harmless since we'd add it here anyway. */
3922 {
3926 }
3929 {
3930 /* 13.3.1.5: For direct-initialization, those explicit
3931 conversion functions that are not hidden within S and
3932 yield type T or a type that can be converted to type T
3933 with a qualification conversion (4.4) are also candidate
3934 functions. */
3935 /* 13.3.1.6 doesn't have a parallel restriction, but it should;
3936 I've raised this issue with the committee. --jason 9/2011 */
3939 }
3941 {
3943 cand->reason
3946 }
3949 {
3950 /* 13.3.3.1.2: If the user-defined conversion is specified by
3951 a specialization of a conversion function template, the
3952 second standard conversion sequence shall have exact match
3953 rank. */
3956 }
3957 }
3958 }
3962 {
3966 }
3970 {
3972 {
3973 auto_diagnostic_group d;
3977 }
3986 /* If there are viable candidates, don't set ICS_BAD_FLAG; an
3987 ambiguous conversion is no worse than another user-defined
3988 conversion. */
3991 }
3993 tree convtype;
3997 /* DR 5: [in the first step of copy-initialization]...if the function
3998 is a constructor, the call initializes a temporary of the
3999 cv-unqualified version of the destination type. */
4001 else
4003 /* Build the user conversion sequence. */
4004 conv = build_conv
4006 convtype,
4012 /* Remember that this was a list-initialization. */
4016 /* Combine it with the second conversion sequence. */
4021 }
4023 /* Wrapper for above. */
4025 tree
4027 tsubst_flags_t complain)
4028 {
4030 tree ret;
4036 {
4039 else
4040 {
4043 }
4044 }
4045 else
4050 }
4052 /* Subroutine of convert_nontype_argument.
4054 EXPR is an expression used in a context that requires a converted
4055 constant-expression, such as a template non-type parameter. Do any
4056 necessary conversions (that are permitted for converted
4057 constant-expressions) to convert it to the desired type.
4059 If conversion is successful, returns the converted expression;
4060 otherwise, returns error_mark_node. */
4062 tree
4064 {
4067 tree t;
4073 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4080 /* A converted constant expression of type T is an expression, implicitly
4081 converted to type T, where the converted expression is a constant
4082 expression and the implicit conversion sequence contains only
4084 * user-defined conversions,
4085 * lvalue-to-rvalue conversions (7.1),
4086 * array-to-pointer conversions (7.2),
4087 * function-to-pointer conversions (7.3),
4088 * qualification conversions (7.5),
4089 * integral promotions (7.6),
4090 * integral conversions (7.8) other than narrowing conversions (11.6.4),
4091 * null pointer conversions (7.11) from std::nullptr_t,
4092 * null member pointer conversions (7.12) from std::nullptr_t, and
4093 * function pointer conversions (7.13),
4095 and where the reference binding (if any) binds directly. */
4100 {
4102 {
4103 /* A conversion function is OK. If it isn't constexpr, we'll
4104 complain later that the argument isn't constant. */
4106 /* The lvalue-to-rvalue conversion is OK. */
4108 /* Array-to-pointer and function-to-pointer. */
4110 /* Function pointer conversions. */
4112 /* Qualification conversions. */
4118 {
4124 }
4134 /* Integral promotion or conversion. */
4137 /* Conversion from nullptr to pointer or pointer-to-member. */
4143 /* fall through. */
4148 }
4149 }
4151 /* Avoid confusing convert_nontype_argument by introducing
4152 a redundant conversion to the same reference type. */
4155 {
4159 }
4162 {
4166 }
4167 else
4168 {
4173 }
4175 /* Free all the conversions we allocated. */
4179 }
4181 /* Do any initial processing on the arguments to a function call. */
4185 {
4187 tree arg;
4190 {
4194 {
4198 }
4201 }
4203 }
4205 /* Perform overload resolution on FN, which is called with the ARGS.
4207 Return the candidate function selected by overload resolution, or
4208 NULL if the event that overload resolution failed. In the case
4209 that overload resolution fails, *CANDIDATES will be the set of
4210 candidates considered, and ANY_VIABLE_P will be set to true or
4211 false to indicate whether or not any of the candidates were
4212 viable.
4214 The ARGS should already have gone through RESOLVE_ARGS before this
4215 function is called. */
4222 {
4224 tree explicit_targs;
4235 /* Check FN. */
4242 {
4246 }
4248 /* Add the various candidate functions. */
4253 LOOKUP_NORMAL,
4259 else
4264 }
4266 /* Print an error message about being unable to build a call to FN with
4267 ARGS. ANY_VIABLE_P indicates whether any candidate functions could
4268 be located; CANDIDATES is a possibly empty list of such
4269 functions. */
4271 static void
4274 {
4277 {
4280 }
4286 auto_diagnostic_group d;
4290 else
4295 }
4297 /* Return an expression for a call to FN (a namespace-scope function,
4298 or a static member function) with the ARGS. This may change
4299 ARGS. */
4301 tree
4303 tsubst_flags_t complain)
4304 {
4308 tree result;
4311 {
4315 }
4320 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4324 complain);
4327 {
4329 {
4330 // If there is a single (non-viable) function candidate,
4331 // let the error be diagnosed by cp_build_function_call_vec.
4336 // Otherwise, emit notes for non-viable candidates.
4338 }
4340 }
4341 else
4342 {
4344 /* If fn is template_id_expr, the call has explicit template arguments
4345 (e.g. func<int>(5)), communicate this info to build_over_call
4346 through flags so that later we can use it to decide whether to warn
4347 about peculiar null pointer conversion. */
4349 {
4350 /* If overload resolution selects a specialization of a
4351 function concept for non-dependent template arguments,
4352 the expression is true if the constraints are satisfied
4353 and false otherwise.
4355 NOTE: This is an extension of Concepts Lite TS that
4356 allows constraints to be used in expressions. */
4358 {
4364 }
4367 }
4370 }
4372 /* Free all the conversions we allocated. */
4376 }
4378 /* Build a call to a global operator new. FNNAME is the name of the
4379 operator (either "operator new" or "operator new[]") and ARGS are
4380 the arguments provided. This may change ARGS. *SIZE points to the
4381 total number of bytes required by the allocation, and is updated if
4382 that is changed here. *COOKIE_SIZE is non-NULL if a cookie should
4383 be used. If this function determines that no cookie should be
4384 used, after all, *COOKIE_SIZE is set to NULL_TREE. If SIZE_CHECK
4385 is not NULL_TREE, it is evaluated before calculating the final
4386 array size, and if it fails, the array size is replaced with
4387 (size_t)-1 (usually triggering a std::bad_alloc exception). If FN
4388 is non-NULL, it will be set, upon return, to the allocation
4389 function called. */
4391 tree
4396 {
4398 tree fns;
4405 /* Set to (size_t)-1 if the size check fails. */
4407 {
4413 }
4419 /* Based on:
4421 [expr.new]
4423 If this lookup fails to find the name, or if the allocated type
4424 is not a class type, the allocation function's name is looked
4425 up in the global scope.
4427 we disregard block-scope declarations of "operator new". */
4432 {
4439 /* If no aligned allocation function matches, try again without the
4440 alignment. */
4441 }
4443 /* Figure out what function is being called. */
4446 complain);
4448 /* If no suitable function could be found, issue an error message
4449 and give up. */
4451 {
4455 }
4457 /* If a cookie is required, add some extra space. Whether
4458 or not a cookie is required cannot be determined until
4459 after we know which function was called. */
4461 {
4463 tree arg_types;
4466 /* Skip the size_t parameter. */
4468 /* Check the remaining parameters (if any). */
4472 ptr_type_node))
4474 /* If we need a cookie, adjust the number of bytes allocated. */
4476 {
4477 /* Update the total size. */
4480 {
4481 /* Set to (size_t)-1 if the size check fails. */
4485 }
4486 /* Update the argument list to reflect the adjusted size. */
4488 }
4489 else
4491 }
4493 /* Tell our caller which function we decided to call. */
4497 /* Build the CALL_EXPR. */
4499 }
4501 /* Build a new call to operator(). This may change ARGS. */
4503 static tree
4505 {
4522 {
4524 /* It's no good looking for an overloaded operator() on a
4525 pointer-to-member-function. */
4529 }
4532 {
4536 }
4537 else
4541 {
4545 }
4547 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4551 {
4559 }
4564 {
4572 {
4579 add_template_conv_candidate
4583 else
4587 }
4588 }
4590 /* Be strict here because if we choose a bad conversion candidate, the
4591 errors we get won't mention the call context. */
4594 {
4596 {
4597 auto_diagnostic_group d;
4601 }
4603 }
4604 else
4605 {
4608 {
4610 {
4611 auto_diagnostic_group d;
4615 }
4617 }
4622 else
4623 {
4627 else
4628 {
4631 }
4634 }
4635 }
4637 /* Free all the conversions we allocated. */
4641 }
4643 /* Wrapper for above. */
4645 tree
4647 {
4648 tree ret;
4653 }
4655 /* Called by op_error to prepare format strings suitable for the error
4656 function. It concatenates a prefix (controlled by MATCH), ERRMSG,
4657 and a suffix (controlled by NTYPES). */
4661 {
4671 else
4675 }
4677 static void
4680 {
4685 {
4691 else
4703 else
4713 else
4724 else
4734 else
4739 else
4743 else
4748 }
4749 }
4751 /* Return the implicit conversion sequence that could be used to
4752 convert E1 to E2 in [expr.cond]. */
4756 {
4762 /* [expr.cond]
4764 If E2 is an lvalue: E1 can be converted to match E2 if E1 can be
4765 implicitly converted (clause _conv_) to the type "lvalue reference to
4766 T2", subject to the constraint that in the conversion the
4767 reference must bind directly (_dcl.init.ref_) to an lvalue.
4769 If E2 is an xvalue: E1 can be converted to match E2 if E1 can be
4770 implicitly converted to the type "rvalue reference to T2", subject to
4771 the constraint that the reference must bind directly. */
4773 {
4776 t1,
4777 e1,
4779 LOOKUP_NO_TEMP_BIND|LOOKUP_NO_RVAL_BIND
4781 complain);
4784 }
4786 /* If E2 is a prvalue or if neither of the conversions above can be done
4787 and at least one of the operands has (possibly cv-qualified) class
4788 type: */
4792 /* [expr.cond]
4794 If E1 and E2 have class type, and the underlying class types are
4795 the same or one is a base class of the other: E1 can be converted
4796 to match E2 if the class of T2 is the same type as, or a base
4797 class of, the class of T1, and the cv-qualification of T2 is the
4798 same cv-qualification as, or a greater cv-qualification than, the
4799 cv-qualification of T1. If the conversion is applied, E1 is
4800 changed to an rvalue of type T2 that still refers to the original
4801 source class object (or the appropriate subobject thereof). */
4804 {
4806 {
4811 else
4814 }
4815 else
4817 }
4818 else
4819 /* [expr.cond]
4821 Otherwise: E1 can be converted to match E2 if E1 can be implicitly
4822 converted to the type that expression E2 would have if E2 were
4823 converted to an rvalue (or the type it has, if E2 is an rvalue). */
4826 }
4828 /* Implement [expr.cond]. ARG1, ARG2, and ARG3 are the three
4829 arguments to the conditional expression. */
4831 static tree
4833 tsubst_flags_t complain)
4834 {
4835 tree arg2_type;
4836 tree arg3_type;
4845 /* As a G++ extension, the second argument to the conditional can be
4846 omitted. (So that `a ? : c' is roughly equivalent to `a ? a :
4847 c'.) If the second operand is omitted, make sure it is
4848 calculated only once. */
4850 {
4858 /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */
4861 else
4863 }
4865 /* If something has already gone wrong, just pass that fact up the
4866 tree. */
4876 {
4879 /* If arg1 is another cond_expr choosing between -1 and 0,
4880 then we can use its comparison. It may help to avoid
4881 additional comparison, produce more accurate diagnostics
4882 and enables folding. */
4892 /* force_rvalue can return error_mark on valid arguments. */
4903 {
4904 /* Rely on the error messages of the scalar version. */
4913 {
4921 }
4925 /* We could pass complain & tf_warning to unsafe_conversion_p,
4926 but the warnings (like Wsign-conversion) have already been
4927 given by the scalar build_conditional_expr_1. We still check
4928 unsafe_conversion_p to forbid truncating long long -> float. */
4930 {
4935 }
4937 {
4942 }
4952 }
4955 {
4961 {
4965 {
4971 }
4973 {
4979 }
4982 }
4983 }
4989 {
4992 "incompatible vector types in conditional expression: "
4996 }
4999 {
5002 }
5004 }
5006 /* [expr.cond]
5008 The first expression is implicitly converted to bool (clause
5009 _conv_). */
5011 LOOKUP_NORMAL);
5015 /* [expr.cond]
5017 If either the second or the third operand has type (possibly
5018 cv-qualified) void, then the lvalue-to-rvalue (_conv.lval_),
5019 array-to-pointer (_conv.array_), and function-to-pointer
5020 (_conv.func_) standard conversions are performed on the second
5021 and third operands. */
5025 {
5026 /* [expr.cond]
5028 One of the following shall hold:
5030 --The second or the third operand (but not both) is a
5031 throw-expression (_except.throw_); the result is of the type
5032 and value category of the other.
5034 --Both the second and the third operands have type void; the
5035 result is of type void and is a prvalue. */
5038 {
5041 }
5044 {
5047 }
5049 {
5052 }
5053 else
5054 {
5056 {
5059 "second operand to the conditional operator "
5060 "is of type %<void%>, but the third operand is "
5062 else
5064 "third operand to the conditional operator "
5065 "is of type %<void%>, but the second operand is "
5067 }
5069 }
5072 }
5073 /* [expr.cond]
5075 Otherwise, if the second and third operand have different types,
5076 and either has (possibly cv-qualified) class type, or if both are
5077 glvalues of the same value category and the same type except for
5078 cv-qualification, an attempt is made to convert each of those operands
5079 to the type of the other. */
5083 arg3_type)
5086 {
5091 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5097 /* [expr.cond]
5099 If both can be converted, or one can be converted but the
5100 conversion is ambiguous, the program is ill-formed. If
5101 neither can be converted, the operands are left unchanged and
5102 further checking is performed as described below. If exactly
5103 one conversion is possible, that conversion is applied to the
5104 chosen operand and the converted operand is used in place of
5105 the original operand for the remainder of this section. */
5110 {
5112 {
5119 else
5121 }
5123 }
5125 {
5129 /* Even if CONV2 is a valid conversion, the result of the
5130 conversion may be invalid. For example, if ARG3 has type
5131 "volatile X", and X does not have a copy constructor
5132 accepting a "volatile X&", then even if ARG2 can be
5133 converted to X, the conversion will fail. */
5137 }
5139 {
5146 }
5148 /* Free all the conversions we allocated. */
5154 /* If, after the conversion, both operands have class type,
5155 treat the cv-qualification of both operands as if it were the
5156 union of the cv-qualification of the operands.
5158 The standard is not clear about what to do in this
5159 circumstance. For example, if the first operand has type
5160 "const X" and the second operand has a user-defined
5161 conversion to "volatile X", what is the type of the second
5162 operand after this step? Making it be "const X" (matching
5163 the first operand) seems wrong, as that discards the
5164 qualification without actually performing a copy. Leaving it
5165 as "volatile X" seems wrong as that will result in the
5166 conditional expression failing altogether, even though,
5167 according to this step, the one operand could be converted to
5168 the type of the other. */
5176 }
5178 /* [expr.cond]
5180 If the second and third operands are glvalues of the same value
5181 category and have the same type, the result is of that type and
5182 value category. */
5186 {
5191 }
5193 /* [expr.cond]
5195 Otherwise, the result is an rvalue. If the second and third
5196 operand do not have the same type, and either has (possibly
5197 cv-qualified) class type, overload resolution is used to
5198 determine the conversions (if any) to be applied to the operands
5199 (_over.match.oper_, _over.built_). */
5203 {
5208 /* Rearrange the arguments so that add_builtin_candidate only has
5209 to know about two args. In build_builtin_candidate, the
5210 arguments are unscrambled. */
5215 COND_EXPR,
5216 NOP_EXPR,
5218 args,
5221 /* [expr.cond]
5223 If the overload resolution fails, the program is
5224 ill-formed. */
5227 {
5232 }
5235 {
5237 {
5238 auto_diagnostic_group d;
5241 }
5243 }
5245 /* [expr.cond]
5247 Otherwise, the conversions thus determined are applied, and
5248 the converted operands are used in place of the original
5249 operands for the remainder of this section. */
5258 }
5260 /* [expr.cond]
5262 Lvalue-to-rvalue (_conv.lval_), array-to-pointer (_conv.array_),
5263 and function-to-pointer (_conv.func_) standard conversions are
5264 performed on the second and third operands.
5266 We need to force the lvalue-to-rvalue conversion here for class types,
5267 so we get TARGET_EXPRs; trying to deal with a COND_EXPR of class rvalues
5268 that isn't wrapped with a TARGET_EXPR plays havoc with exception
5269 regions. */
5282 /* [expr.cond]
5284 After those conversions, one of the following shall hold:
5286 --The second and third operands have the same type; the result is of
5287 that type. */
5290 /* [expr.cond]
5292 --The second and third operands have arithmetic or enumeration
5293 type; the usual arithmetic conversions are performed to bring
5294 them to a common type, and the result is of that type. */
5299 {
5300 /* In this case, there is always a common type. */
5302 arg3_type);
5305 "implicit conversion from %qH to %qI to "
5307 loc);
5311 {
5315 /* Two enumerators from the same enumeration can have different
5321 }
5328 {
5332 }
5336 }
5337 /* [expr.cond]
5339 --The second and third operands have pointer type, or one has
5340 pointer type and the other is a null pointer constant; pointer
5341 conversions (_conv.ptr_) and qualification conversions
5342 (_conv.qual_) are performed to bring them to their composite
5343 pointer type (_expr.rel_). The result is of the composite
5344 pointer type.
5346 --The second and third operands have pointer to member type, or
5347 one has pointer to member type and the other is a null pointer
5348 constant; pointer to member conversions (_conv.mem_) and
5349 qualification conversions (_conv.qual_) are performed to bring
5350 them to a common type, whose cv-qualification shall match the
5351 cv-qualification of either the second or the third operand.
5352 The result is of the common type. */
5360 {
5363 complain);
5368 }
5371 {
5376 }
5381 valid_operands:
5383 {
5384 /* Let lvalue_kind know this was a glvalue. */
5387 }
5391 /* If the ARG2 and ARG3 are the same and don't have side-effects,
5392 warn here, because the COND_EXPR will be turned into ARG2. */
5399 /* We can't use result_type below, as fold might have returned a
5400 throw_expr. */
5403 {
5404 /* Expand both sides into the same slot, hopefully the target of
5405 the ?: expression. We used to check for TARGET_EXPRs here,
5406 but now we sometimes wrap them in NOP_EXPRs so the test would
5407 fail. */
5410 /* If this expression is an rvalue, but might be mistaken for an
5411 lvalue, we must add a NON_LVALUE_EXPR. */
5413 }
5414 else
5418 }
5420 /* Wrapper for above. */
5422 tree
5424 tsubst_flags_t complain)
5425 {
5426 tree ret;
5431 }
5433 /* OPERAND is an operand to an expression. Perform necessary steps
5434 required before using it. If OPERAND is NULL_TREE, NULL_TREE is
5435 returned. */
5437 static tree
5439 {
5441 {
5444 /* Make sure the template type is instantiated now. */
5446 }
5449 }
5451 /* Add each of the viable functions in FNS (a FUNCTION_DECL or
5452 OVERLOAD) to the CANDIDATES, returning an updated list of
5453 CANDIDATES. The ARGS are the arguments provided to the call;
5454 if FIRST_ARG is non-null it is the implicit object argument,
5455 otherwise the first element of ARGS is used if needed. The
5456 EXPLICIT_TARGS are explicit template arguments provided.
5457 TEMPLATE_ONLY is true if only template functions should be
5458 considered. CONVERSION_PATH, ACCESS_PATH, and FLAGS are as for
5459 add_function_candidate. */
5461 static void
5463 tree return_type,
5468 tsubst_flags_t complain)
5469 {
5470 tree ctype;
5474 unification_kind_t strict;
5479 /* Precalculate special handling of constructors and conversion ops. */
5482 {
5486 /* We're doing return_type(x). */
5488 else
5489 /* We're doing x.operator return_type(). */
5491 /* [over.match.funcs] For conversion functions, the function
5492 is considered to be a member of the class of the implicit
5493 object argument for the purpose of defining the type of
5494 the implicit object parameter. */
5496 }
5497 else
5498 {
5500 {
5502 /* For list-initialization we consider explicit constructors
5503 and complain if one is chosen. */
5504 check_converting
5507 }
5510 }
5514 else
5515 /* Delay creating the implicit this parameter until it is needed. */
5519 {
5531 {
5532 /* Figure out where the object arg comes from. If this
5533 function is a non-static member and we didn't get an
5534 implicit object argument, move it out of args. */
5536 {
5538 tree arg;
5545 }
5549 }
5553 fn,
5554 ctype,
5555 explicit_targs,
5556 fn_first_arg,
5557 fn_args,
5558 return_type,
5559 access_path,
5560 conversion_path,
5561 flags,
5562 strict,
5563 complain);
5566 fn,
5567 ctype,
5568 fn_first_arg,
5569 fn_args,
5570 access_path,
5571 conversion_path,
5572 flags,
5573 NULL,
5574 complain);
5575 }
5576 }
5578 /* Returns 1 if P0145R2 says that the LHS of operator CODE is evaluated first,
5579 -1 if the RHS is evaluated first, or 0 if the order is unspecified. */
5581 static int
5583 {
5585 {
5586 // 5. b @= a
5590 // 6. a[b]
5594 // 1. a.b
5595 // Not overloadable (yet).
5596 // 2. a->b
5597 // Only one argument.
5598 // 3. a->*b
5600 // 7. a << b
5602 // 8. a >> b
5608 }
5609 }
5611 static tree
5614 {
5635 {
5638 }
5645 {
5650 /* Use build_op_new_call and build_op_delete_call instead. */
5654 /* Use build_op_call instead. */
5661 /* These are saved for the sake of warn_logical_operator. */
5671 /* These are saved for the sake of maybe_warn_bool_compare. */
5676 /* =, ->, [], () must be non-static member functions. */
5680 /* FALLTHRU */
5688 }
5694 /* Use build_conditional_expr instead. */
5710 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5713 /* Add namespace-scope operators to the list of functions to
5714 consider. */
5716 {
5722 }
5728 /* Add class-member operators to the candidate set. */
5730 {
5731 tree fns;
5735 {
5738 }
5746 }
5747 /* Per 13.3.1.2/3, 2nd bullet, if no operand has a class type, then
5748 only non-member functions that have type T1 or reference to
5749 cv-qualified-opt T1 for the first argument, if the first argument
5750 has an enumeration type, or T2 or reference to cv-qualified-opt
5751 T2 for the second argument, if the second argument has an
5752 enumeration type. Filter out those that don't match. */
5754 {
5758 {
5768 {
5774 && (same_type_ignoring_top_level_qualifiers_p
5779 }
5781 /* No argument has an appropriate type, so remove this
5782 candidate function from the list. */
5784 {
5787 }
5788 }
5789 }
5795 {
5798 /* For these, the built-in candidates set is empty
5799 [over.match.oper]/3. We don't want non-strict matches
5800 because exact matches are always possible with built-in
5801 operators. The built-in candidate set for COMPONENT_REF
5802 would be empty too, but since there are no such built-in
5803 operators, we accept non-strict matches for them. */
5810 }
5814 {
5816 {
5819 /* Don't try anything fancy if we're not allowed to produce
5820 errors. */
5824 /* Look for an `operator++ (int)'. Pre-1985 C++ didn't
5825 distinguish between prefix and postfix ++ and
5826 operator++() was used for both, so we allow this with
5827 -fpermissive. */
5828 else
5829 {
5835 }
5842 else
5848 /* The caller will deal with these. */
5858 {
5859 /* If one of the arguments of the operator represents
5860 an invalid use of member function pointer, try to report
5861 a meaningful error ... */
5866 else
5867 {
5868 /* ... Otherwise, report the more generic
5869 "no matching operator found" error */
5870 auto_diagnostic_group d;
5873 }
5874 }
5877 }
5878 }
5879 else
5880 {
5883 {
5885 {
5886 auto_diagnostic_group d;
5889 }
5891 }
5893 {
5899 else
5905 {
5910 /* This prevents build_new_function_call from discarding this
5911 function during instantiation of the enclosing template. */
5914 /* Specify evaluation order as per P0145R2. */
5917 {
5928 }
5929 }
5930 }
5931 else
5932 {
5933 /* Give any warnings we noticed during overload resolution. */
5935 {
5939 }
5941 /* Check for comparison of different enum types. */
5943 {
5955 {
5959 }
5963 }
5965 /* We need to strip any leading REF_BIND so that bitfields
5966 don't cause errors. This should not remove any important
5967 conversions, because builtins don't apply to class
5968 objects directly. */
5975 {
5979 else
5982 /* We need to call warn_logical_operator before
5983 converting arg2 to a boolean_type, but after
5984 decaying an enumerator to its value. */
5991 }
5993 {
5998 }
6000 }
6001 }
6003 user_defined_result_ready:
6005 /* Free all the conversions we allocated. */
6011 builtin:
6013 {
6028 /* Fall through. */
6041 /* Fall through. */
6074 complain),
6077 /* The caller will deal with these. */
6085 }
6087 }
6089 /* Wrapper for above. */
6091 tree
6095 {
6096 tree ret;
6102 }
6104 /* CALL was returned by some call-building function; extract the actual
6105 CALL_EXPR from any bits that have been tacked on, e.g. by
6106 convert_from_reference. */
6108 tree
6110 {
6121 }
6123 /* Returns true if FN has two parameters, of which the second has type
6124 size_t. */
6126 static bool
6128 {
6140 }
6142 /* True if T, an allocation function, has std::align_val_t as its second
6143 argument. */
6145 bool
6147 {
6153 }
6155 /* Returns true iff T, an element of an OVERLOAD chain, is a usual deallocation
6156 function (3.7.4.2 [basic.stc.dynamic.deallocation]) with a parameter of
6157 std::align_val_t. */
6159 static bool
6161 {
6165 /* A template instance is never a usual deallocation function,
6166 regardless of its signature. */
6182 }
6184 /* Returns true iff T, an element of an OVERLOAD chain, is a usual
6185 deallocation function (3.7.4.2 [basic.stc.dynamic.deallocation]). */
6187 bool
6189 {
6190 /* A template instance is never a usual deallocation function,
6191 regardless of its signature. */
6196 /* If a class T has a member deallocation function named operator delete
6197 with exactly one parameter, then that function is a usual
6198 (non-placement) deallocation function. If class T does not declare
6199 such an operator delete but does declare a member deallocation
6200 function named operator delete with exactly two parameters, the second
6201 of which has type std::size_t (18.2), then this function is a usual
6202 deallocation function. */
6214 }
6216 /* Build a call to operator delete. This has to be handled very specially,
6217 because the restrictions on what signatures match are different from all
6218 other call instances. For a normal delete, only a delete taking (void *)
6219 or (void *, size_t) is accepted. For a placement delete, only an exact
6220 match with the placement new is accepted.
6222 CODE is either DELETE_EXPR or VEC_DELETE_EXPR.
6223 ADDR is the pointer to be deleted.
6224 SIZE is the size of the memory block to be deleted.
6225 GLOBAL_P is true if the delete-expression should not consider
6226 class-specific delete operators.
6227 PLACEMENT is the corresponding placement new call, or NULL_TREE.
6229 If this call to "operator delete" is being generated as part to
6230 deallocate memory allocated via a new-expression (as per [expr.new]
6231 which requires that if the initialization throws an exception then
6232 we call a deallocation function), then ALLOC_FN is the allocation
6233 function. */
6235 tree
6239 {
6253 /* In [class.free]
6255 If the result of the lookup is ambiguous or inaccessible, or if
6256 the lookup selects a placement deallocation function, the
6257 program is ill-formed.
6259 Therefore, we ask lookup_fnfields to complain about ambiguity. */
6260 {
6264 }
6265 else
6271 /* Strip const and volatile from addr. */
6275 {
6276 /* "A declaration of a placement deallocation function matches the
6277 declaration of a placement allocation function if it has the same
6278 number of parameters and, after parameter transformations (8.3.5),
6279 all parameter types except the first are identical."
6281 So we build up the function type we want and ask instantiate_type
6282 to get it for us. */
6293 /* "If the lookup finds the two-parameter form of a usual deallocation
6294 function (3.7.4.2) and that function, considered as a placement
6295 deallocation function, would have been selected as a match for the
6296 allocation function, the program is ill-formed." */
6298 {
6306 /* But if the class has an operator delete (void *), then that is
6307 the usual deallocation function, so we shouldn't complain
6308 about using the operator delete (void *, size_t). */
6312 {
6317 }
6318 /* Before C++14 a two-parameter global deallocation function is
6319 always a placement deallocation function, but warn if
6320 -Wc++14-compat. */
6322 {
6324 {
6325 auto_diagnostic_group d;
6328 }
6330 }
6333 {
6334 auto_diagnostic_group d;
6336 {
6337 /* Only mention C++14 for namespace-scope delete. */
6340 else
6342 "%qD is a usual (non-placement) deallocation "
6344 }
6345 }
6346 else
6348 ok:;
6349 }
6350 }
6351 else
6352 /* "Any non-placement deallocation function matches a non-placement
6353 allocation function. If the lookup finds a single matching
6354 deallocation function, that function will be called; otherwise, no
6355 deallocation function will be called." */
6357 {
6360 {
6362 {
6365 }
6367 /* -- If the type has new-extended alignment, a function with a
6368 parameter of type std::align_val_t is preferred; otherwise a
6369 function without such a parameter is preferred. If exactly one
6370 preferred function is found, that function is selected and the
6371 selection process terminates. If more than one preferred
6372 function is found, all non-preferred functions are eliminated
6373 from further consideration. */
6375 {
6381 {
6385 }
6386 }
6388 /* -- If the deallocation functions have class scope, the one
6389 without a parameter of type std::size_t is selected. */
6394 /* -- If the type is complete and if, for the second alternative
6395 (delete array) only, the operand is a pointer to a class type
6396 with a non-trivial destructor or a (possibly multi-dimensional)
6397 array thereof, the function with a parameter of type std::size_t
6398 is selected.
6400 -- Otherwise, it is unspecified whether a deallocation function
6401 with a parameter of type std::size_t is selected. */
6402 else
6403 {
6407 /* We need a cookie to determine the array size. */
6409 }
6415 }
6416 }
6418 /* If we have a matching function, call it. */
6420 {
6423 /* If the FN is a member function, make sure that it is
6424 accessible. */
6427 complain);
6429 /* Core issue 901: It's ok to new a type with deleted delete. */
6434 {
6435 /* The placement args might not be suitable for overload
6436 resolution at this point, so build the call directly. */
6446 }
6447 else
6448 {
6449 tree ret;
6455 {
6458 }
6462 }
6463 }
6465 /* [expr.new]
6467 If no unambiguous matching deallocation function can be found,
6468 propagating the exception does not cause the object's memory to
6469 be freed. */
6471 {
6475 alloc_fn);
6477 }
6483 }
6485 /* If the current scope isn't allowed to access DECL along
6486 BASETYPE_PATH, give an error. The most derived class in
6487 BASETYPE_PATH is the one used to qualify DECL. DIAG_DECL is
6488 the declaration to use in the error diagnostic. */
6490 bool
6493 {
6498 {
6499 /* 7.3.3/18: The additional constructors are accessible if they would be
6500 accessible when used to construct an object of the corresponding base
6501 class. */
6505 }
6508 {
6510 {
6514 {
6520 }
6522 {
6528 }
6529 else
6530 {
6535 }
6536 }
6538 }
6541 }
6543 /* Initialize a temporary of type TYPE with EXPR. The FLAGS are a
6544 bitwise or of LOOKUP_* values. If any errors are warnings are
6545 generated, set *DIAGNOSTIC_FN to "error" or "warning",
6546 respectively. If no diagnostics are generated, set *DIAGNOSTIC_FN
6547 to NULL. */
6549 static tree
6552 {
6558 /* If the source is a packed field, calling the copy constructor will require
6559 binding the field to the reference parameter to the copy constructor, and
6560 we'll end up with an infinite loop. If we can use a bitwise copy, then
6561 do that now. */
6577 }
6579 /* Perform warnings about peculiar, but valid, conversions from/to NULL.
6580 Also handle a subset of zero as null warnings.
6581 EXPR is implicitly converted to type TOTYPE.
6582 FN and ARGNUM are used for diagnostics. */
6584 static void
6586 {
6587 /* Issue warnings about peculiar, but valid, uses of NULL. */
6590 {
6591 source_location loc =
6598 else
6601 }
6603 /* Issue warnings if "false" is converted to a NULL pointer */
6606 {
6609 "converting %<false%> to pointer type for argument %P "
6611 else
6614 }
6615 /* Handle zero as null pointer warnings for cases other
6616 than EQ_EXPR and NE_EXPR */
6619 {
6620 source_location loc =
6623 }
6624 }
6626 /* We gave a diagnostic during a conversion. If this was in the second
6627 standard conversion sequence of a user-defined conversion sequence, say
6628 which user-defined conversion. */
6630 static void
6632 {
6636 {
6640 }
6641 }
6643 /* Locate the parameter with the given index within FNDECL.
6644 ARGNUM is zero based, -1 indicates the `this' argument of a method.
6645 Return the location of the FNDECL itself if there are problems. */
6647 location_t
6649 {
6651 tree param;
6653 /* Locate param by index within DECL_ARGUMENTS (fndecl). */
6657 ;
6659 /* If something went wrong (e.g. if we have a builtin and thus no arguments),
6660 return the location of FNDECL. */
6665 }
6667 /* Perform the conversions in CONVS on the expression EXPR. FN and
6668 ARGNUM are used for diagnostics. ARGNUM is zero based, -1
6669 indicates the `this' argument of a method. INNER is nonzero when
6670 being called to continue a conversion chain. It is negative when a
6671 reference binding will be applied, positive otherwise. If
6672 ISSUE_CONVERSION_WARNINGS is true, warnings about suspicious
6673 conversions will be emitted if appropriate. If C_CAST_P is true,
6674 this conversion is coming from a C-style cast; in that case,
6675 conversions to inaccessible bases are permitted. */
6677 static tree
6681 {
6683 diagnostic_t diag_kind;
6699 {
6703 /* Give a helpful error if this is bad because of excess braces. */
6708 {
6714 }
6716 /* Give a helpful error if this is bad because a conversion to bool
6717 from std::nullptr_t requires direct-initialization. */
6725 {
6727 {
6728 auto_diagnostic_group d;
6731 totype);
6737 complain);
6741 complain);
6742 else
6748 }
6750 {
6754 complain);
6756 }
6761 complain);
6764 }
6766 {
6772 }
6778 }
6784 {
6786 {
6790 /* We chose the surrogate function from add_conv_candidate, now we
6791 actually need to build the conversion. */
6797 /* When converting from an init list we consider explicit
6798 constructors, but actually trying to call one is an error. */
6801 /* Unless this is for direct-list-initialization. */
6803 /* And in C++98 a default constructor can't be explicit. */
6805 {
6811 {
6812 auto_diagnostic_group d;
6818 }
6819 else
6822 }
6824 /* If we're initializing from {}, it's value-initialization. */
6828 {
6835 {
6838 }
6840 }
6844 /* Pass LOOKUP_NO_CONVERSION so rvalue/base handling knows not to allow
6845 any more UDCs. */
6847 complain);
6849 /* If this is a constructor or a function returning an aggr type,
6850 we need to build up a TARGET_EXPR. */
6852 {
6855 /* Remember that this was list-initialization. */
6858 }
6861 }
6864 {
6870 else
6872 }
6881 /* If __null has been converted to an integer type, we do not want to
6882 continue to warn about uses of EXPR as an integer, rather than as a
6883 pointer. */
6887 /* We leave bad_p off ck_ambig because overload resolution considers
6888 it valid, it just fails when we try to perform it. So we need to
6889 check complain here, too. */
6891 {
6892 /* Call build_user_type_conversion again for the error. */
6900 }
6904 {
6905 /* Conversion to std::initializer_list<T>. */
6913 /* Convert all the elements. */
6915 {
6926 }
6927 /* Build up the array. */
6928 elttype = cp_build_qualified_type
6932 /* Take the address explicitly rather than via decay_conversion
6933 to avoid the error about taking the address of a temporary. */
6939 /* Build up the initializer_list object. Note: fail gracefully
6940 if the object cannot be completed because, for example, no
6941 definition is provided (c++/80956). */
6951 }
6955 {
6964 }
6967 complain);
6974 };
6984 {
6988 {
6990 {
6991 auto_diagnostic_group d;
6996 }
6998 }
7003 /* Don't introduce copies when passing arguments along to the inherited
7004 constructor. */
7006 && flag_new_inheriting_ctors
7012 /* Copy-list-initialization doesn't actually involve a copy. */
7015 /* Fall through. */
7018 {
7019 /* We are going to bind a reference directly to a base-class
7020 subobject of EXPR. */
7021 /* Build an expression for `*((base*) &expr)'. */
7025 }
7027 /* Copy-initialization where the cv-unqualified version of the source
7028 type is the same class as, or a derived class of, the class of the
7029 destination [is treated as direct-initialization]. [dcl.init] */
7032 /* This conversion is being done in the context of a user-defined
7033 conversion (i.e. the second step of copy-initialization), so
7034 don't allow any more. */
7036 else
7039 /* standard_conversion got LOOKUP_PREFER_RVALUE. */
7043 {
7044 auto_diagnostic_group d;
7049 }
7054 {
7058 {
7060 auto_diagnostic_group d;
7072 else
7079 }
7081 /* If necessary, create a temporary.
7083 VA_ARG_EXPR and CONSTRUCTOR expressions are special cases
7084 that need temporaries, even when their types are reference
7085 compatible with the type of reference being bound, so the
7086 upcoming call to cp_build_addr_expr doesn't fail. */
7090 {
7091 /* Otherwise, a temporary of type "cv1 T1" is created and
7092 initialized from the initializer expression using the rules
7093 for a non-reference copy-initialization (8.5). */
7102 {
7103 /* If the reference is volatile or non-const, we
7104 cannot create a temporary. */
7111 else
7115 }
7116 /* If the source is a packed field, and we must use a copy
7117 constructor, then building the target expr will require
7118 binding the field to the reference parameter to the
7119 copy constructor, and we'll end up with an infinite
7120 loop. If we can use a bitwise copy, then we'll be
7121 OK. */
7125 {
7129 }
7131 {
7134 }
7136 }
7138 /* Take the address of the thing to which we will bind the
7139 reference. */
7144 /* Convert it to a pointer to the type referred to by the
7145 reference. This will adjust the pointer if a derived to
7146 base conversion is being performed. */
7149 /* Convert the pointer to the desired reference type. */
7151 }
7157 /* ??? Should the address of a transaction-safe pointer point to the TM
7158 clone, and this conversion look up the primary function? */
7162 /* Warn about deprecated conversion if appropriate. */
7178 }
7188 else
7192 }
7194 /* ARG is being passed to a varargs function. Perform any conversions
7195 required. Return the converted value. */
7197 tree
7199 {
7200 tree arg_type;
7203 /* [expr.call]
7205 The lvalue-to-rvalue, array-to-pointer, and function-to-pointer
7206 standard conversions are performed. */
7209 /* [expr.call]
7211 If the argument has integral or enumeration type that is subject
7212 to the integral promotions (_conv.prom_), or a floating point
7213 type that is subject to the floating point promotion
7214 (_conv.fpprom_), the value of the argument is converted to the
7215 promoted type before the call. */
7220 {
7224 "implicit conversion from %qH to %qI when passing "
7228 }
7232 {
7234 {
7236 complain);
7246 }
7247 else
7249 }
7255 /* In a template (or ill-formed code), we can have an incomplete type
7256 even after require_complete_type_sfinae, in which case we don't know
7257 whether it has trivial copy or not. */
7260 {
7261 /* [expr.call] 5.2.2/7:
7262 Passing a potentially-evaluated argument of class type (Clause 9)
7263 with a non-trivial copy constructor or a non-trivial destructor
7264 with no corresponding parameter is conditionally-supported, with
7265 implementation-defined semantics.
7267 We support it as pass-by-invisible-reference, just like a normal
7268 value parameter.
7270 If the call appears in the context of a sizeof expression,
7271 it is not potentially-evaluated. */
7274 {
7278 "passing objects of non-trivially-copyable "
7280 arg_type);
7282 }
7283 /* Build up a real lvalue-to-rvalue conversion in case the
7284 copy constructor is trivial but not callable. */
7288 }
7291 }
7293 /* va_arg (EXPR, TYPE) is a builtin. Make sure it is not abused. */
7295 tree
7297 {
7299 {
7303 }
7313 {
7316 }
7320 {
7321 /* conditionally-supported behavior [expr.call] 5.2.2/7. Let's treat
7322 it as pass by invisible reference. */
7324 "receiving objects of non-trivially-copyable type %q#T "
7330 }
7334 /* Wrap the VA_ARG_EXPR in a TARGET_EXPR now so other code doesn't need to
7335 know how to handle it. */
7338 }
7340 /* TYPE has been given to va_arg. Apply the default conversions which
7341 would have happened when passed via ellipsis. Return the promoted
7342 type, or the passed type if there is no change. */
7344 tree
7346 {
7347 tree promote;
7349 /* Perform the array-to-pointer and function-to-pointer
7350 conversions. */
7358 }
7360 /* ARG is a default argument expression being passed to a parameter of
7361 the indicated TYPE, which is a parameter to FN. PARMNUM is the
7362 zero-based argument number. Do any required conversions. Return
7363 the converted value. */
7366 void
7370 void
7374 tree
7376 tsubst_flags_t complain)
7377 {
7379 tree t;
7381 /* See through clones. */
7383 /* And inheriting ctors. */
7387 /* Detect recursion. */
7390 {
7394 }
7396 /* If the ARG is an unparsed default argument expression, the
7397 conversion cannot be performed. */
7399 {
7404 }
7411 /* Due to:
7413 [dcl.fct.default]
7415 The names in the expression are bound, and the semantic
7416 constraints are checked, at the point where the default
7417 expressions appears.
7419 we must not perform access checks here. */
7421 /* We must make a copy of ARG, in case subsequent processing
7422 alters any part of it. */
7427 complain);
7434 }
7436 /* Returns the type which will really be used for passing an argument of
7437 type TYPE. */
7439 tree
7441 {
7442 /* Pass classes with copy ctors by invisible reference. */
7444 {
7446 /* There are no other pointers to this temporary. */
7448 }
7456 }
7458 /* Actually perform the appropriate conversion. */
7460 tree
7462 {
7463 tree bitfield_type;
7465 /* If VAL is a bitfield, then -- since it has already been converted
7466 to TYPE -- it cannot have a precision greater than TYPE.
7468 If it has a smaller precision, we must widen it here. For
7469 example, passing "int f:3;" to a function expecting an "int" will
7470 not result in any conversion before this point.
7472 If the precision is the same we must not risk widening. For
7473 example, the COMPONENT_REF for a 32-bit "long long" bitfield will
7474 often have type "int", even though the C++ type for the field is
7475 "long long". If the value is being passed to a function
7476 expecting an "int", then no conversions will be required. But,
7477 if we call convert_bitfield_to_declared_type, the bitfield will
7478 be converted to "long long". */
7485 ;
7486 /* Pass classes with copy ctors by invisible reference. */
7495 {
7497 {
7505 "argument of function call might be a candidate "
7507 }
7509 }
7511 }
7513 /* Returns non-zero iff FN is a function with magic varargs, i.e. ones for
7514 which just decay_conversion or no conversions at all should be done.
7515 This is true for some builtins which don't act like normal functions.
7516 Return 2 if no conversions at all should be done, 1 if just
7517 decay_conversion. Return 3 for special treatment of the 3rd argument
7518 for __builtin_*_overflow_p. */
7520 int
7522 {
7525 {
7540 }
7543 }
7545 /* Returns the decl of the dispatcher function if FN is a function version. */
7547 tree
7549 {
7559 {
7563 }
7568 }
7570 /* fn is a function version dispatcher that is marked used. Mark all the
7571 semantically identical function versions it will dispatch as used. */
7573 void
7575 {
7592 /* All semantically identical versions are chained. Traverse and mark each
7593 one of them as used. */
7596 {
7599 }
7600 }
7602 /* Build a call to "the copy constructor" for the type of A, even if it
7603 wouldn't be selected by normal overload resolution. Used for
7604 diagnostics. */
7606 static tree
7608 {
7619 }
7621 /* Return true iff T refers to a base field. */
7623 static bool
7625 {
7634 }
7636 /* We can't elide a copy from a function returning by value to a base
7637 subobject, as the callee might clobber tail padding. Return true iff this
7638 could be that case. */
7640 static bool
7642 {
7643 /* Copy elision only happens with a TARGET_EXPR. */
7647 /* It's safe to elide the copy for a class with no tail padding. */
7650 /* It's safe to elide the copy if we aren't initializing a base object. */
7654 /* build_compound_expr pushes COMPOUND_EXPR inside TARGET_EXPR. */
7658 {
7659 /* We'll end up copying from each of the arms of the COND_EXPR directly
7660 into the target, so look at them. */
7665 }
7668 }
7670 /* True iff C is a conversion that binds a reference to a prvalue. */
7672 static bool
7674 {
7691 }
7693 /* Call the trivial destructor for INSTANCE, which can be either an lvalue of
7694 class type or a pointer to class type. */
7696 tree
7698 {
7702 {
7703 no_clobber:
7705 }
7708 {
7712 }
7714 /* A trivial destructor should still clobber the object. */
7718 }
7720 /* Subroutine of the various build_*_call functions. Overload resolution
7721 has chosen a winning candidate CAND; build up a CALL_EXPR accordingly.
7722 ARGS is a TREE_LIST of the unconverted arguments to the call. FLAGS is a
7723 bitmask of various LOOKUP_* flags which apply to the call itself. */
7725 static tree
7727 {
7735 tree val;
7744 /* In a template, there is no need to perform all of the work that
7745 is normally done. We are only interested in the type of the call
7746 expression, i.e., the return type of the function. Any semantic
7747 errors will be deferred until the template is instantiated. */
7749 {
7751 tree return_type;
7757 else
7758 /* Otherwise set TREE_USED for the benefit of -Wunused-function.
7759 See PR80598. */
7766 else
7767 {
7770 tree arg;
7778 }
7788 }
7790 /* Give any warnings we noticed during overload resolution. */
7792 {
7796 }
7798 /* Core issue 2327: P0135 doesn't say how to handle the case where the
7799 argument to the copy constructor ends up being a prvalue after
7800 conversion. Let's do the normal processing, but pretend we aren't
7801 actually using the copy constructor. */
7809 {
7812 }
7814 /* OK, we're actually calling this inherited constructor; set its deletedness
7815 appropriately. We can get away with doing this here because calling is
7816 the only way to refer to a constructor. */
7820 /* Make =delete work with SFINAE. */
7822 {
7826 }
7829 {
7830 tree access_fn;
7831 /* If FN is a template function, two cases must be considered.
7832 For example:
7834 struct A {
7835 protected:
7836 template <class T> void f();
7837 };
7838 template <class T> struct B {
7839 protected:
7840 void g();
7841 };
7842 struct C : A, B<int> {
7843 using A::f; // #1
7844 using B<int>::g; // #2
7845 };
7847 In case #1 where `A::f' is a member template, DECL_ACCESS is
7848 recorded in the primary template but not in its specialization.
7849 We check access of FN using its primary template.
7851 In case #2, where `B<int>::g' has a DECL_TEMPLATE_INFO simply
7852 because it is a member of class template B, DECL_ACCESS is
7853 recorded in the specialization `B<int>::g'. We cannot use its
7854 primary template because `B<T>::g' and `B<int>::g' may have
7855 different access. */
7859 else
7864 }
7866 /* If we're checking for implicit delete, don't bother with argument
7867 conversions. */
7869 {
7873 /* Reject bad conversions now. */
7875 /* else continue to get conversion error. */
7876 }
7878 not_really_used:
7880 /* N3276 magic doesn't apply to nested calls. */
7883 /* No-Cleanup doesn't apply to nested calls either. */
7887 /* Find maximum size of vector to hold converted arguments. */
7894 /* The implicit parameters to a constructor are not considered by overload
7895 resolution, and must be of the proper type. */
7897 {
7898 tree object_arg;
7900 {
7903 }
7904 else
7905 {
7908 }
7911 /* We should never try to call the abstract constructor. */
7915 {
7919 }
7922 {
7923 /* The implicit move specified in 15.8.3/3 fails "...if the type of
7924 the first parameter of the selected constructor is not an rvalue
7925 reference to the object's type (possibly cv-qualified)...." */
7932 }
7933 }
7934 /* Bypass access control for 'this' parameter. */
7936 {
7939 ? first_arg
7942 tree converted_arg;
7943 tree base_binfo;
7949 {
7951 {
7952 auto_diagnostic_group d;
7957 }
7958 else
7960 }
7962 /* See if the function member or the whole class type is declared
7963 final and the call can be devirtualized. */
7968 /* [class.mfct.nonstatic]: If a nonstatic member function of a class
7969 X is called for an object that is not of type X, or of a type
7970 derived from X, the behavior is undefined.
7972 So we can assume that anything passed as 'this' is non-null, and
7973 optimize accordingly. */
7975 /* Convert to the base in which the function was declared. */
7978 arg,
7981 /* Check that the base class is accessible. */
7984 {
7989 else
7991 }
7992 /* If fn was found by a using declaration, the conversion path
7993 will be to the derived class, not the base declaring fn. We
7994 must convert from derived to base. */
8005 else
8009 }
8014 {
8021 /* If the argument is NULL and used to (implicitly) instantiate a
8022 template function (and bind one of the template arguments to
8023 the type of 'long int'), we don't want to warn about passing NULL
8024 to non-pointer argument.
8025 For example, if we have this template function:
8027 template<typename T> void func(T x) {}
8029 we want to warn (when -Wconversion is enabled) in this case:
8031 void foo() {
8032 func<int>(NULL);
8033 }
8035 but not in this case:
8037 void foo() {
8038 func(NULL);
8039 }
8040 */
8047 /* Warn about initializer_list deduction that isn't currently in the
8048 working draft. */
8050 && flag_deduce_init_list
8054 {
8067 {
8075 }
8076 }
8078 /* Set user_conv_p on the argument conversions, so rvalue/base handling
8079 knows not to allow any more UDCs. This needs to happen after we
8080 process cand->warnings. */
8089 arg_complain);
8094 else
8096 }
8098 /* Default arguments */
8100 {
8106 complain);
8110 }
8112 /* Ellipsis */
8115 {
8118 {
8119 /* Do no conversions for certain magic varargs. */
8123 }
8125 /* For other magic varargs only do decay_conversion. */
8130 {
8131 /* Avoid infinite recursion trying to call A(...). */
8133 /* Try to call the actual copy constructor for a good error. */
8136 }
8137 else
8142 }
8147 /* Avoid to do argument-transformation, if warnings for format, and for
8148 nonnull are disabled. Just in case that at least one of them is active
8149 the check_function_arguments function might warn about something. */
8153 || warn_format
8154 || warn_suggest_attribute_format
8156 {
8160 {
8161 /* For -Wformat undo the implicit passing by hidden reference
8162 done by convert_arg_to_ellipsis. */
8166 else
8168 }
8172 }
8175 {
8176 /* Check for passing ellipsis arguments to an inherited constructor. We
8177 could handle this by open-coding the inherited constructor rather than
8178 defining it, but let's not bother now. */
8182 {
8184 {
8188 }
8190 }
8192 /* A base constructor inheriting from a virtual base doesn't get the
8193 inherited arguments, just this and __vtt. */
8196 }
8198 /* Avoid actually calling copy constructors and copy assignment operators,
8199 if possible. */
8206 /* It's unsafe to elide the constructor when handling
8207 a noexcept-expression, it may evaluate to the wrong
8208 value (c++/53025). */
8210 {
8211 tree targ;
8213 tree fa;
8216 /* Pull out the real argument, disregarding const-correctness. */
8218 /* Strip the reference binding for the constructor parameter. */
8222 /* But don't strip any other reference bindings; binding a temporary to a
8223 reference prevents copy elision. */
8229 {
8234 }
8235 else
8240 else
8243 /* In C++17 we shouldn't be copying a TARGET_EXPR except into a base
8244 subobject. */
8247 || force_elide
8248 /* It's from binding the ref parm to a packed field. */
8251 /* See unsafe_copy_elision_p. */
8258 /* [class.copy]: the copy constructor is implicitly defined even if the
8259 implementation elided its use. But don't warn about deprecation when
8260 eliding a temporary, as then no copy is actually performed. */
8265 {
8269 }
8270 else
8273 /* If we're creating a temp and we already have one, don't create a
8274 new one. If we're not creating a temp but we get one, use
8275 INIT_EXPR to collapse the temp into our target. Otherwise, if the
8276 ctor is trivial, do a bitwise copy with a simple TARGET_EXPR for a
8277 temp or an INIT_EXPR otherwise. */
8279 {
8284 }
8287 {
8292 }
8293 }
8297 {
8298 tree to = cp_stabilize_reference
8306 {
8307 /* Avoid copying empty classes. */
8310 }
8312 {
8316 "assignment from temporary initializer_list does not "
8320 }
8321 else
8322 {
8323 /* We must only copy the non-tail padding parts. */
8331 build_index_type
8340 }
8345 }
8347 {
8351 {
8354 no_cleanup_complain);
8355 else
8357 }
8358 }
8366 /* Warn if the built-in writes to an object of a non-trivial type. */
8373 /* Don't mess with virtual lookup in instantiate_non_dependent_expr;
8374 virtual functions can't be constexpr. */
8376 {
8377 tree t;
8384 complain);
8390 }
8391 else
8392 {
8396 }
8402 {
8404 /* build_new_op_1 will clear this when appropriate. */
8406 }
8408 {
8412 }
8414 }
8416 namespace
8417 {
8419 /* Return the DECL of the first non-static subobject of class TYPE
8420 that satisfies the predicate PRED or null if none can be found. */
8423 tree
8425 {
8430 {
8437 }
8443 {
8449 }
8452 }
8454 struct NonPublicField
8455 {
8457 {
8459 }
8460 };
8462 /* Return the DECL of the first non-public subobject of class TYPE
8463 or null if none can be found. */
8467 {
8469 }
8471 struct NonTrivialField
8472 {
8474 {
8476 }
8477 };
8479 /* Return the DECL of the first non-trivial subobject of class TYPE
8480 or null if none can be found. */
8484 {
8486 }
8490 /* Return true if all copy and move assignment operator overloads for
8491 class TYPE are trivial and at least one of them is not deleted and,
8492 when ACCESS is set, accessible. Return false otherwise. Set
8493 HASASSIGN to true when the TYPE has a (not necessarily trivial)
8494 copy or move assignment. */
8496 static bool
8498 {
8502 /* Iterate over overloads of the assignment operator, checking
8503 accessible copy assignments for triviality. */
8506 {
8509 /* Skip operators that aren't copy assignments. */
8516 /* Skip template assignment operators and deleted functions. */
8526 /* Break early when both properties have been determined. */
8529 }
8531 /* Return true if they're all trivial and one of the expressions
8532 TYPE() = TYPE() or TYPE() = (TYPE&)() is valid. */
8537 }
8539 /* Return true if all copy and move ctor overloads for class TYPE are
8540 trivial and at least one of them is not deleted and, when ACCESS is
8541 set, accessible. Return false otherwise. Set each element of HASCTOR[]
8542 to true when the TYPE has a (not necessarily trivial) default and copy
8543 (or move) ctor, respectively. */
8545 static bool
8547 {
8552 {
8555 /* Skip template constructors. */
8561 /* Skip ctors other than default, copy, and move. */
8577 /* Break early when both properties have been determined. */
8580 }
8583 }
8585 /* Issue a warning on a call to the built-in function FNDECL if it is
8586 a raw memory write whose destination is not an object of (something
8587 like) trivial or standard layout type with a non-deleted assignment
8588 and copy ctor. Detects const correctness violations, corrupting
8589 references, virtual table pointers, and bypassing non-trivial
8590 assignments. */
8592 static void
8595 {
8596 /* Except for bcopy where it's second, the destination pointer is
8597 the first argument for all functions handled here. Compute
8598 the index of the destination and source arguments. */
8608 /* Determine the type of the pointed-to object and whether it's
8609 a complete class type. */
8615 /* Check to see if the raw memory call is made by a non-static member
8616 function with THIS as the destination argument for the destination
8617 type. If so, and if the class has no non-trivial bases or members,
8618 be more permissive. */
8622 {
8627 /* FIXME: The following if statement is overly permissive (see
8628 bug 84851). Remove it in GCC 9. */
8640 }
8642 /* True if the class is trivial. */
8645 /* Set to true if DESTYPE has an accessible copy assignment. */
8647 /* True if all of the class' overloaded copy assignment operators
8648 are all trivial (and not deleted) and at least one of them is
8649 accessible. */
8652 /* Set to true if DESTTYPE has an accessible default and copy ctor,
8653 respectively. */
8656 /* True if all of the class' overloaded copy constructors are all
8657 trivial (and not deleted) and at least one of them is accessible. */
8660 /* Set FLD to the first private/protected member of the class. */
8663 /* The warning format string. */
8665 /* A suggested alternative to offer instead of the raw memory call.
8666 Empty string when none can be come up with. */
8671 {
8674 {
8675 /* Diagnose setting non-copy-assignable or non-trivial types,
8676 or types with a private member, to (potentially) non-zero
8677 bytes. Since the value of the bytes being written is unknown,
8678 suggest using assignment instead (if one exists). Also warn
8679 for writes into objects for which zero-initialization doesn't
8680 mean all bits clear (pointer-to-member data, where null is all
8681 bits set). Since the value being written is (most likely)
8682 non-zero, simply suggest assignment (but not copy assignment). */
8690 {
8693 "%qD writing to an object of type %#qT with "
8696 }
8702 }
8703 /* Fall through. */
8706 /* Similarly to the above, diagnose clearing non-trivial or non-
8707 standard layout objects, or objects of types with no assignmenmt.
8708 Since the value being written is known to be zero, suggest either
8709 copy assignment, copy ctor, or default ctor as an alternative,
8710 depending on what's available. */
8733 /* Determine the type of the source object. */
8737 else
8740 /* Since it's impossible to determine wheter the byte copy is
8741 being used in place of assignment to an existing object or
8742 as a substitute for initialization, assume it's the former.
8743 Determine the best alternative to use instead depending on
8744 what's not deleted. */
8765 srctype))
8766 {
8767 /* Warn when copying into a non-trivial object from an object
8768 of a different type other than void or char. */
8770 "%qD copying an object of non-trivial type "
8773 }
8778 srctype))
8779 {
8782 "%qD copying an object of type %#qT with "
8783 "%qs member %qD from an array of %#qT; use "
8786 }
8788 {
8793 /* Finally, warn on partial copies. */
8794 unsigned HOST_WIDE_INT typesize
8800 "a non-trivial type %#qT leaves %wu "
8803 "a non-trivial type %#qT leaves %wu "
8806 }
8821 {
8825 /* Finally, warn on reallocation into insufficient space. */
8827 "%qD moving an object of non-trivial type "
8830 sz);
8831 }
8836 }
8839 {
8843 else
8846 }
8850 }
8852 /* Build and return a call to FN, using NARGS arguments in ARGARRAY.
8853 This function performs no overload resolution, conversion, or other
8854 high-level operations. */
8856 tree
8858 tsubst_flags_t complain)
8859 {
8860 tree fndecl;
8862 /* Remember roughly where this call is. */
8869 /* Check that arguments to builtin functions match the expectations. */
8871 && !processing_template_decl
8873 {
8876 /* We need to take care that values to BUILT_IN_NORMAL
8877 are reduced. */
8884 }
8889 /* 5.2.2/11: If a function call is a prvalue of object type: if the
8890 function call is either the operand of a decltype-specifier or the
8891 right operand of a comma operator that is the operand of a
8892 decltype-specifier, a temporary object is not introduced for the
8893 prvalue. The type of the prvalue may be incomplete. */
8895 {
8901 {
8904 }
8905 }
8907 }
8909 /* Returns the value to use for the in-charge parameter when making a
8910 call to a function with the indicated NAME.
8912 FIXME:Can't we find a neater way to do this mapping? */
8914 tree
8916 {
8918 {
8922 }
8923 else
8924 {
8930 }
8933 }
8935 /* We've built up a constructor call RET. Complain if it delegates to the
8936 constructor we're currently compiling. */
8938 static void
8940 {
8946 }
8948 /* Build a call to a constructor, destructor, or an assignment
8949 operator for INSTANCE, an expression with class type. NAME
8950 indicates the special member function to call; *ARGS are the
8951 arguments. ARGS may be NULL. This may change ARGS. BINFO
8952 indicates the base of INSTANCE that is to be passed as the `this'
8953 parameter to the member function called.
8955 FLAGS are the LOOKUP_* flags to use when processing the call.
8957 If NAME indicates a complete object constructor, INSTANCE may be
8958 NULL_TREE. In this case, the caller will call build_cplus_new to
8959 store the newly constructed object into a VAR_DECL. */
8961 tree
8964 {
8965 tree fns;
8966 /* The type of the subobject to be constructed or destroyed. */
8967 tree class_type;
8969 tree ret;
8977 {
8980 /* Shortcut to avoid lazy destructor declaration. */
8982 }
8985 {
8986 /* Resolve the name. */
8991 }
8997 /* Handle the special case where INSTANCE is NULL_TREE. */
9000 else
9001 {
9002 /* Convert to the base class, if necessary. */
9005 {
9007 /* For constructors and destructors, either the base is
9008 non-virtual, or it is virtual but we are doing the
9009 conversion from a constructor or destructor for the
9010 complete object. In either case, we can convert
9011 statically. */
9013 else
9014 {
9015 /* However, for assignment operators, we must convert
9016 dynamically if the base is virtual. */
9020 }
9021 }
9022 }
9026 /* In C++17, "If the initializer expression is a prvalue and the
9027 cv-unqualified version of the source type is the same class as the class
9028 of the destination, the initializer expression is used to initialize the
9029 destination object." Handle that here to avoid doing overload
9030 resolution. */
9034 {
9044 && (same_type_ignoring_top_level_qualifiers_p
9046 {
9055 /* Avoid change of behavior on Wunused-var-2.C. */
9058 }
9059 }
9063 /* When making a call to a constructor or destructor for a subobject
9064 that uses virtual base classes, pass down a pointer to a VTT for
9065 the subobject. */
9069 {
9070 tree vtt;
9071 tree sub_vtt;
9073 /* If the current function is a complete object constructor
9074 or destructor, then we fetch the VTT directly.
9075 Otherwise, we look it up using the VTT we were given. */
9083 else
9087 {
9090 }
9093 }
9098 complain);
9109 }
9111 /* Return the NAME, as a C string. The NAME indicates a function that
9112 is a member of TYPE. *FREE_P is set to true if the caller must
9113 free the memory returned.
9115 Rather than go through all of this, we should simply set the names
9116 of constructors and destructors appropriately, and dispense with
9117 ctor_identifier, dtor_identifier, etc. */
9121 {
9124 /* Assume that we will not allocate memory. */
9126 /* Constructors and destructors are special. */
9128 {
9129 pretty_name
9131 /* For a destructor, add the '~'. */
9133 {
9135 /* Remember that we need to free the memory allocated. */
9137 }
9138 }
9140 {
9143 TFF_PLAIN_IDENTIFIER),
9144 NULL);
9145 /* Remember that we need to free the memory allocated. */
9147 }
9148 else
9152 }
9154 /* Build a call to "INSTANCE.FN (ARGS)". If FN_P is non-NULL, it will
9155 be set, upon return, to the function called. ARGS may be NULL.
9156 This may change ARGS. */
9158 static tree
9162 {
9167 tree optype;
9169 tree name;
9172 tree call;
9173 tree fn;
9176 tree orig_instance;
9177 tree orig_fns;
9183 /* We don't know what function we're going to call, yet. */
9192 {
9196 }
9201 /* Dismantle the baselink to collect all the information we need. */
9209 {
9213 }
9224 /* Under DR 147 A::A() is an invalid constructor call,
9225 not a functional cast. */
9227 {
9233 auto_diagnostic_group d;
9240 complain);
9242 }
9245 {
9250 }
9252 /* Process the argument list. */
9254 {
9259 }
9261 /* Consider the object argument to be used even if we end up selecting a
9262 static member function. */
9265 /* Figure out whether to skip the first argument for the error
9266 message we will display to users if an error occurs. We don't
9267 want to display any compiler-generated arguments. The "this"
9268 pointer hasn't been added yet. However, we must remove the VTT
9269 pointer if this is a call to a base-class constructor or
9270 destructor. */
9273 {
9274 /* Callers should explicitly indicate whether they want to ctor
9275 the complete object or just the part without virtual bases. */
9278 /* Remove the VTT pointer, if present. */
9283 /* It's OK to call destructors and constructors on cv-qualified
9284 objects. Therefore, convert the INSTANCE to the unqualified
9285 type, if necessary. */
9287 {
9291 }
9292 }
9293 else
9296 /* For the overload resolution we need to find the actual `this`
9297 that would be captured if the call turns out to be to a
9298 non-static member function. Do not actually capture it at this
9299 point. */
9301 /* Constructors don't use the enclosing 'this'. */
9303 else
9306 /* Get the high-water mark for the CONVERSION_OBSTACK. */
9309 /* The number of arguments artificial parms in ARGS; we subtract one because
9310 there's no 'this' in ARGS. */
9313 /* If CONSTRUCTOR_IS_DIRECT_INIT is set, this was a T{ } form
9314 initializer, not T({ }). */
9318 {
9325 /* If the initializer list has no elements and T is a class type with
9326 a default constructor, the object is value-initialized. Handle
9327 this here so we don't need to handle it wherever we use
9328 build_special_member_call. */
9331 /* For a user-provided default constructor, use the normal
9332 mechanisms so that protected access works. */
9337 /* If BASETYPE is an aggregate, we need to do aggregate
9338 initialization. */
9340 {
9343 }
9346 {
9352 }
9354 /* Otherwise go ahead with overload resolution. */
9359 }
9360 else
9369 {
9371 {
9372 auto_diagnostic_group d;
9379 else
9380 {
9385 {
9388 }
9396 }
9398 }
9400 }
9401 else
9402 {
9405 {
9408 tree arglist;
9411 {
9416 auto_diagnostic_group d;
9420 else
9426 }
9428 }
9429 else
9430 {
9438 {
9439 /* This is not an error, it is runtime undefined
9440 behavior. */
9449 fn);
9450 }
9455 {
9460 {
9461 /* We captured 'this' in the current lambda now that
9462 we know we really need it. */
9464 }
9466 /* We can't tell until instantiation time whether we can use
9468 else
9469 {
9472 fn);
9474 }
9475 }
9478 {
9479 /* Optimize away vtable lookup if we know that this
9480 function can't be overridden. We need to check if
9481 the context and the type where we found fn are the same,
9482 actually FN might be defined in a different class
9483 type because of a using-declaration. In this case, we
9484 do not want to perform a non-virtual call. */
9486 && same_type_ignoring_top_level_qualifiers_p
9492 /* Now we know what function is being called. */
9495 /* Build the actual CALL_EXPR. */
9497 /* In an expression of the form `a->f()' where `f' turns
9498 out to be a static member function, `a' is
9499 none-the-less evaluated. */
9503 {
9504 /* But avoid the implicit lvalue-rvalue conversion when 'a'
9505 is volatile. */
9510 }
9514 /* An explicit call of the form "x->~X()" has type
9515 "void". However, on platforms where destructors
9516 return "this" (i.e., those where
9517 targetm.cxx.cdtor_returns_this is true), such calls
9518 will appear to have a return value of pointer type
9519 to the low-level call machinery. We do not want to
9520 change the low-level machinery, since we want to be
9521 able to optimize "delete f()" on such platforms as
9522 "operator delete(~X(f()))" (rather than generating
9523 "t = f(), ~X(t), operator delete (t)"). */
9525 }
9526 }
9527 }
9530 {
9536 {
9539 }
9542 call = (build_min_non_dep_call_vec
9546 orig_args));
9551 }
9553 /* Free all the conversions we allocated. */
9560 }
9562 /* Wrapper for above. */
9564 tree
9568 {
9569 tree ret;
9575 }
9577 /* Returns true iff standard conversion sequence ICS1 is a proper
9578 subsequence of ICS2. */
9580 static bool
9582 {
9583 /* We can assume that a conversion of the same code
9584 between the same types indicates a subsequence since we only get
9585 here if the types we are converting from are the same. */
9592 {
9602 /* At this point, ICS1 cannot be a proper subsequence of
9603 ICS2. We can get a USER_CONV when we are comparing the
9604 second standard conversion sequence of two user conversion
9605 sequences. */
9620 }
9621 }
9623 /* Returns nonzero iff DERIVED is derived from BASE. The inputs may
9624 be any _TYPE nodes. */
9626 bool
9628 {
9632 /* We only allow proper derivation here. The DERIVED_FROM_P macro
9633 considers every class derived from itself. */
9636 }
9638 /* We build the ICS for an implicit object parameter as a pointer
9639 conversion sequence. However, such a sequence should be compared
9640 as if it were a reference conversion sequence. If ICS is the
9641 implicit conversion sequence for an implicit object parameter,
9642 modify it accordingly. */
9644 static void
9646 {
9648 {
9649 /* [over.match.funcs]
9651 For non-static member functions, the type of the
9652 implicit object parameter is "reference to cv X"
9653 where X is the class of which the function is a
9654 member and cv is the cv-qualification on the member
9655 function declaration. */
9657 tree reference_type;
9659 /* The `this' parameter is a pointer to a class type. Make the
9660 implicit conversion talk about a reference to that same class
9661 type. */
9674 }
9675 }
9677 /* If *ICS is a REF_BIND set *ICS to the remainder of the conversion,
9678 and return the initial reference binding conversion. Otherwise,
9679 leave *ICS unchanged and return NULL. */
9683 {
9685 {
9690 }
9693 }
9695 /* Compare two implicit conversion sequences according to the rules set out in
9696 [over.ics.rank]. Return values:
9698 1: ics1 is better than ics2
9699 -1: ics2 is better than ics1
9700 0: ics1 and ics2 are indistinguishable */
9702 static int
9704 {
9705 tree from_type1;
9706 tree from_type2;
9707 tree to_type1;
9708 tree to_type2;
9715 /* REF_BINDING is nonzero if the result of the conversion sequence
9716 is a reference type. In that case REF_CONV is the reference
9717 binding conversion. */
9721 /* Compare badness before stripping the reference conversion. */
9727 /* Handle implicit object parameters. */
9731 /* Handle reference parameters. */
9735 /* List-initialization sequence L1 is a better conversion sequence than
9736 list-initialization sequence L2 if L1 converts to
9737 std::initializer_list<X> for some X and L2 does not. */
9743 /* [over.ics.rank]
9745 When comparing the basic forms of implicit conversion sequences (as
9746 defined in _over.best.ics_)
9748 --a standard conversion sequence (_over.ics.scs_) is a better
9749 conversion sequence than a user-defined conversion sequence
9750 or an ellipsis conversion sequence, and
9752 --a user-defined conversion sequence (_over.ics.user_) is a
9753 better conversion sequence than an ellipsis conversion sequence
9754 (_over.ics.ellipsis_). */
9755 /* Use BAD_CONVERSION_RANK because we already checked for a badness
9756 mismatch. If both ICS are bad, we try to make a decision based on
9757 what would have happened if they'd been good. This is not an
9758 extension, we'll still give an error when we build up the call; this
9759 just helps us give a more helpful error message. */
9769 /* Both conversions are ellipsis conversions. */
9772 /* User-defined conversion sequence U1 is a better conversion sequence
9773 than another user-defined conversion sequence U2 if they contain the
9774 same user-defined conversion operator or constructor and if the sec-
9775 ond standard conversion sequence of U1 is better than the second
9776 standard conversion sequence of U2. */
9778 /* Handle list-conversion with the same code even though it isn't always
9779 ranked as a user-defined conversion and it doesn't have a second
9780 standard conversion sequence; it will still have the desired effect.
9781 Specifically, we need to do the reference binding comparison at the
9782 end of this function. */
9785 {
9801 {
9806 }
9807 else
9808 {
9809 /* For ambiguous or aggregate conversions, use the target type as
9810 a proxy for the conversion function. */
9813 }
9815 /* We can just fall through here, after setting up
9816 FROM_TYPE1 and FROM_TYPE2. */
9819 }
9820 else
9821 {
9825 /* We're dealing with two standard conversion sequences.
9827 [over.ics.rank]
9829 Standard conversion sequence S1 is a better conversion
9830 sequence than standard conversion sequence S2 if
9832 --S1 is a proper subsequence of S2 (comparing the conversion
9833 sequences in the canonical form defined by _over.ics.scs_,
9834 excluding any Lvalue Transformation; the identity
9835 conversion sequence is considered to be a subsequence of
9836 any non-identity conversion sequence */
9847 }
9849 /* One sequence can only be a subsequence of the other if they start with
9850 the same type. They can start with different types when comparing the
9851 second standard conversion sequence in two user-defined conversion
9852 sequences. */
9854 {
9859 }
9861 /* [over.ics.rank]
9863 Or, if not that,
9865 --the rank of S1 is better than the rank of S2 (by the rules
9866 defined below):
9868 Standard conversion sequences are ordered by their ranks: an Exact
9869 Match is a better conversion than a Promotion, which is a better
9870 conversion than a Conversion.
9872 Two conversion sequences with the same rank are indistinguishable
9873 unless one of the following rules applies:
9875 --A conversion that does not a convert a pointer, pointer to member,
9876 or std::nullptr_t to bool is better than one that does.
9878 The ICS_STD_RANK automatically handles the pointer-to-bool rule,
9879 so that we do not have to check it explicitly. */
9888 /* A conversion from scalar arithmetic type to complex is worse than a
9889 conversion between scalar arithmetic types. */
9896 {
9899 else
9901 }
9907 {
9912 }
9913 /* The rules for pointers to members A::* are just like the rules
9914 for pointers A*, except opposite: if B is derived from A then
9915 A::* converts to B::*, not vice versa. For that reason, we
9916 switch the from_ and to_ variables here. */
9923 {
9928 }
9933 {
9934 /* This was one of the pointer or pointer-like conversions.
9936 [over.ics.rank]
9938 --If class B is derived directly or indirectly from class A,
9939 conversion of B* to A* is better than conversion of B* to
9940 void*, and conversion of A* to void* is better than
9941 conversion of B* to void*. */
9944 {
9946 deref_from_type2))
9949 deref_from_type1))
9951 }
9954 {
9956 {
9958 {
9960 deref_to_type1))
9962 }
9963 /* We know that DEREF_TO_TYPE1 is `void' here. */
9965 deref_to_type2))
9967 }
9968 }
9971 {
9972 /* [over.ics.rank]
9974 --If class B is derived directly or indirectly from class A
9975 and class C is derived directly or indirectly from B,
9977 --conversion of C* to B* is better than conversion of C* to
9978 A*,
9980 --conversion of B* to A* is better than conversion of C* to
9981 A* */
9983 {
9985 deref_to_type2))
9988 deref_to_type1))
9990 }
9992 {
9994 deref_from_type1))
9997 deref_from_type2))
9999 }
10000 }
10001 }
10004 {
10007 /* [over.ics.rank]
10009 --binding of an expression of type C to a reference of type
10010 B& is better than binding an expression of type C to a
10011 reference of type A&
10013 --conversion of C to B is better than conversion of C to A, */
10016 {
10021 }
10022 }
10025 {
10028 /* [over.ics.rank]
10030 --binding of an expression of type B to a reference of type
10031 A& is better than binding an expression of type C to a
10032 reference of type A&,
10034 --conversion of B to A is better than conversion of C to A */
10037 {
10042 }
10043 }
10045 /* [over.ics.rank]
10047 --S1 and S2 differ only in their qualification conversion and yield
10048 similar types T1 and T2 (_conv.qual_), respectively, and the cv-
10049 qualification signature of type T1 is a proper subset of the cv-
10050 qualification signature of type T2 */
10054 {
10058 }
10060 /* [over.ics.rank]
10062 --S1 and S2 are reference bindings (_dcl.init.ref_) and neither refers
10063 to an implicit object parameter of a non-static member function
10064 declared without a ref-qualifier, and either S1 binds an lvalue
10065 reference to an lvalue and S2 binds an rvalue reference or S1 binds an
10066 rvalue reference to an rvalue and S2 binds an lvalue reference (C++0x
10067 draft standard, 13.3.3.2)
10069 --S1 and S2 are reference bindings (_dcl.init.ref_), and the
10070 types to which the references refer are the same type except for
10071 top-level cv-qualifiers, and the type to which the reference
10072 initialized by S2 refers is more cv-qualified than the type to
10073 which the reference initialized by S1 refers.
10075 DR 1328 [over.match.best]: the context is an initialization by
10076 conversion function for direct reference binding (13.3.1.6) of a
10077 reference to function type, the return type of F1 is the same kind of
10078 reference (i.e. lvalue or rvalue) as the reference being initialized,
10079 and the return type of F2 is not. */
10082 {
10089 {
10093 /* Don't prefer a bad conversion that drops cv-quals to a bad
10094 conversion with the wrong rvalueness. */
10098 }
10101 {
10105 {
10106 /* Prefer the one that drops fewer cv-quals. */
10111 }
10113 }
10114 }
10116 /* Neither conversion sequence is better than the other. */
10118 }
10120 /* The source type for this standard conversion sequence. */
10122 static tree
10124 {
10126 {
10131 }
10133 }
10135 /* Note a warning about preferring WINNER to LOSER. We do this by storing
10136 a pointer to LOSER and re-running joust to produce the warning if WINNER
10137 is actually used. */
10139 static void
10141 {
10147 }
10149 /* Compare two candidates for overloading as described in
10150 [over.match.best]. Return values:
10152 1: cand1 is better than cand2
10153 -1: cand2 is better than cand1
10154 0: cand1 and cand2 are indistinguishable */
10156 static int
10158 tsubst_flags_t complain)
10159 {
10165 /* Candidates that involve bad conversions are always worse than those
10166 that don't. */
10172 /* If we have two pseudo-candidates for conversions to the same type,
10173 or two candidates for the same function, arbitrarily pick one. */
10178 /* Prefer a non-deleted function over an implicitly deleted move
10179 constructor or assignment operator. This differs slightly from the
10180 wording for issue 1402 (which says the move op is ignored by overload
10181 resolution), but this way produces better error messages. */
10185 {
10192 }
10194 /* a viable function F1
10195 is defined to be a better function than another viable function F2 if
10196 for all arguments i, ICSi(F1) is not a worse conversion sequence than
10197 ICSi(F2), and then */
10199 /* for some argument j, ICSj(F1) is a better conversion sequence than
10200 ICSj(F2) */
10202 /* For comparing static and non-static member functions, we ignore
10203 the implicit object parameter of the non-static function. The
10204 standard says to pretend that the static function has an object
10205 parm, but that won't work with operator overloading. */
10208 {
10214 /* We're comparing a near-match list constructor and a near-match
10215 non-list constructor. Just treat them as unordered. */
10222 else
10223 {
10226 }
10227 }
10230 {
10236 {
10238 && warn_sign_promo
10250 {
10257 else
10262 {
10266 }
10267 else
10269 }
10272 {
10275 }
10277 }
10278 }
10280 /* warn about confusing overload resolution for user-defined conversions,
10281 either between a constructor and a conversion op, or between two
10282 conversion ops. */
10287 {
10293 else
10296 /* We don't want to complain about `X::operator T1 ()'
10297 beating `X::operator T2 () const', when T2 is a no less
10298 cv-qualified version of T1. */
10301 {
10306 {
10309 }
10312 }
10313 else
10319 {
10323 auto_diagnostic_group d;
10327 {
10329 }
10330 }
10331 else
10333 }
10338 /* DR 495 moved this tiebreaker above the template ones. */
10339 /* or, if not that,
10340 the context is an initialization by user-defined conversion (see
10341 _dcl.init_ and _over.match.user_) and the standard conversion
10342 sequence from the return type of F1 to the destination type (i.e.,
10343 the type of the entity being initialized) is a better conversion
10344 sequence than the standard conversion sequence from the return type
10345 of F2 to the destination type. */
10348 {
10352 }
10354 /* or, if not that,
10355 F1 is a non-template function and F2 is a template function
10356 specialization. */
10363 /* or, if not that,
10364 F1 and F2 are template functions and the function template for F1 is
10365 more specialized than the template for F2 according to the partial
10366 ordering rules. */
10369 {
10370 winner = more_specialized_fn
10373 /* [temp.func.order]: The presence of unused ellipsis and default
10374 arguments has no effect on the partial ordering of function
10375 templates. add_function_candidate() will not have
10376 counted the "this" argument for constructors. */
10380 }
10382 // C++ Concepts
10383 // or, if not that, F1 is more constrained than F2.
10385 {
10389 }
10391 /* F1 is generated from a deduction-guide (13.3.1.8) and F2 is not */
10393 {
10395 /* We distinguish between candidates from an explicit deduction guide and
10396 candidates built from a constructor based on DECL_ARTIFICIAL. */
10403 {
10404 /* Prefer the special copy guide over a declared copy/move
10405 constructor. */
10411 /* Prefer a candidate generated from a non-template constructor. */
10416 }
10417 }
10419 /* F1 is a member of a class D, F2 is a member of a base class B of D, and
10420 for all arguments the corresponding parameters of F1 and F2 have the same
10421 type (CWG 2273/2277). */
10426 {
10440 {
10442 {
10447 }
10450 }
10451 }
10453 /* Check whether we can discard a builtin candidate, either because we
10454 have two identical ones or matching builtin and non-builtin candidates.
10456 (Pedantically in the latter case the builtin which matched the user
10457 function should not be added to the overload set, but we spot it here.
10459 [over.match.oper]
10460 ... the builtin candidates include ...
10461 - do not have the same parameter type list as any non-template
10462 non-member candidate. */
10465 {
10471 {
10473 /* Two built-in candidates; arbitrarily pick one. */
10476 /* cand1 is built-in; prefer cand2. */
10478 else
10479 /* cand2 is built-in; prefer cand1. */
10481 }
10482 }
10484 /* For candidates of a multi-versioned function, make the version with
10485 the highest priority win. This version will be checked for dispatching
10486 first. If this version can be inlined into the caller, the front-end
10487 will simply make a direct call to this function. */
10493 {
10499 /* Check if cand1->fn and cand2->fn are versions of the same function. It
10500 is possible that cand1->fn and cand2->fn are function versions but of
10501 different functions. Check types to see if they are versions of the same
10502 function. */
10505 {
10506 /* Always make the version with the higher priority, more
10507 specialized, win. */
10511 else
10513 }
10514 }
10516 /* If the two function declarations represent the same function (this can
10517 happen with declarations in multiple scopes and arg-dependent lookup),
10518 arbitrarily choose one. But first make sure the default args we're
10519 using match. */
10522 {
10529 {
10530 /* Don't crash if the fn is variadic. */
10535 }
10543 {
10546 {
10548 {
10550 {
10551 auto_diagnostic_group d;
10553 "default argument mismatch in "
10555 {
10560 }
10561 }
10562 else
10564 }
10565 else
10568 }
10571 }
10574 }
10576 tweak:
10578 /* Extension: If the worst conversion for one candidate is worse than the
10579 worst conversion for the other, take the first. */
10581 {
10586 {
10591 }
10597 {
10598 /* Don't choose a deleted function over ambiguity. */
10602 {
10603 auto_diagnostic_group d;
10605 "ISO C++ says that these are ambiguous, even "
10606 "though the worst conversion for the first is better than "
10610 }
10611 else
10614 }
10615 }
10619 }
10621 /* Given a list of candidates for overloading, find the best one, if any.
10622 This algorithm has a worst case of O(2n) (winner is last), and a best
10623 case of O(n/2) (totally ambiguous); much better than a sorting
10624 algorithm. */
10628 {
10633 /* Walk through the list once, comparing each current champ to the next
10634 candidate, knocking out a candidate or two with each comparison. */
10637 {
10641 else
10642 {
10644 {
10649 }
10650 else
10651 {
10654 }
10657 }
10658 }
10660 /* Make sure the champ is better than all the candidates it hasn't yet
10661 been compared to. */
10664 challenger != champ
10667 {
10671 }
10674 }
10676 /* Returns nonzero if things of type FROM can be converted to TO. */
10678 bool
10680 {
10682 /* implicit_conversion only considers user-defined conversions
10683 if it has an expression for the call argument list. */
10687 }
10689 /* Returns nonzero if things of type FROM can be converted to TO with a
10690 standard conversion. */
10692 bool
10694 {
10696 }
10698 /* Returns nonzero if ARG (of type FROM) can be converted to TO. */
10700 bool
10702 tsubst_flags_t complain)
10703 {
10708 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10710 /* We want to discard any access checks done for this test,
10711 as we might not be in the appropriate access context and
10712 we'll do the check again when we actually perform the
10713 conversion. */
10720 /* Discard the access checks now. */
10722 /* Free all the conversions we allocated. */
10726 }
10728 /* Like can_convert_arg, but allows dubious conversions as well. */
10730 bool
10732 tsubst_flags_t complain)
10733 {
10737 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10739 /* Try to perform the conversion. */
10742 /* Free all the conversions we allocated. */
10746 }
10748 /* Convert EXPR to TYPE. Return the converted expression.
10750 Note that we allow bad conversions here because by the time we get to
10751 this point we are committed to doing the conversion. If we end up
10752 doing a bad conversion, convert_like will complain. */
10754 tree
10757 {
10764 else
10770 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10778 {
10780 {
10781 /* If expr has unknown type, then it is an overloaded function.
10782 Call instantiate_type to get good error messages. */
10787 else
10788 {
10793 }
10794 }
10796 }
10798 {
10799 /* In a template, we are only concerned about determining the
10800 type of non-dependent expressions, so we do not have to
10801 perform the actual conversion. But for initializers, we
10802 need to be able to perform it at instantiation
10803 (or instantiate_non_dependent_expr) time. */
10807 }
10808 else
10811 /* Free all the conversions we allocated. */
10815 }
10817 tree
10819 {
10821 LOOKUP_IMPLICIT);
10822 }
10824 /* Convert EXPR to TYPE (as a direct-initialization) if that is
10825 permitted. If the conversion is valid, the converted expression is
10826 returned. Otherwise, NULL_TREE is returned, except in the case
10827 that TYPE is a class type; in that case, an error is issued. If
10828 C_CAST_P is true, then this direct-initialization is taking
10829 place as part of a static_cast being attempted as part of a C-style
10830 cast. */
10832 tree
10834 tree expr,
10836 tsubst_flags_t complain)
10837 {
10843 /* [dcl.init]
10845 If the destination type is a (possibly cv-qualified) class type:
10847 -- If the initialization is direct-initialization ...,
10848 constructors are considered. ... If no constructor applies, or
10849 the overload resolution is ambiguous, the initialization is
10850 ill-formed. */
10852 {
10858 }
10860 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10864 c_cast_p,
10869 {
10870 /* In a template, we are only concerned about determining the
10871 type of non-dependent expressions, so we do not have to
10872 perform the actual conversion. But for initializers, we
10873 need to be able to perform it at instantiation
10874 (or instantiate_non_dependent_expr) time. */
10877 }
10878 else
10881 c_cast_p,
10882 complain);
10884 /* Free all the conversions we allocated. */
10888 }
10890 /* When initializing a reference that lasts longer than a full-expression,
10891 this special rule applies:
10893 [class.temporary]
10895 The temporary to which the reference is bound or the temporary
10896 that is the complete object to which the reference is bound
10897 persists for the lifetime of the reference.
10899 The temporaries created during the evaluation of the expression
10900 initializing the reference, except the temporary to which the
10901 reference is bound, are destroyed at the end of the
10902 full-expression in which they are created.
10904 In that case, we store the converted expression into a new
10905 VAR_DECL in a new scope.
10907 However, we want to be careful not to create temporaries when
10908 they are not required. For example, given:
10910 struct B {};
10911 struct D : public B {};
10912 D f();
10913 const B& b = f();
10915 there is no need to copy the return value from "f"; we can just
10916 extend its lifetime. Similarly, given:
10918 struct S {};
10919 struct T { operator S(); };
10920 T t;
10921 const S& s = t;
10923 we can extend the lifetime of the return value of the conversion
10924 operator.
10926 The next several functions are involved in this lifetime extension. */
10928 /* DECL is a VAR_DECL or FIELD_DECL whose type is a REFERENCE_TYPE. The
10929 reference is being bound to a temporary. Create and return a new
10930 VAR_DECL with the indicated TYPE; this variable will store the value to
10931 which the reference is bound. */
10933 tree
10935 {
10938 /* Register the variable. */
10941 {
10942 /* Namespace-scope or local static; give it a mangled name. */
10943 /* FIXME share comdat with decl? */
10954 }
10955 else
10956 /* Create a new cleanup level if necessary. */
10960 }
10962 /* EXPR is the initializer for a variable DECL of reference or
10963 std::initializer_list type. Create, push and return a new VAR_DECL
10964 for the initializer so that it will live as long as DECL. Any
10965 cleanup for the new variable is returned through CLEANUP, and the
10966 code to initialize the new variable is returned through INITP. */
10968 static tree
10971 {
10972 tree init;
10973 tree type;
10974 tree var;
10976 /* Create the temporary variable. */
10980 /* If the rvalue is the result of a function call it will be
10981 a TARGET_EXPR. If it is some other construct (such as a
10982 member access expression where the underlying object is
10983 itself the result of a function call), turn it into a
10984 TARGET_EXPR here. It is important that EXPR be a
10985 TARGET_EXPR below since otherwise the INIT_EXPR will
10986 attempt to make a bitwise copy of EXPR to initialize
10987 VAR. */
10993 {
10997 }
10999 /* Recursively extend temps in this initializer. */
11003 /* Any reference temp has a non-trivial initializer. */
11006 /* If the initializer is constant, put it in DECL_INITIAL so we get
11007 static initialization and use in constant expressions. */
11009 /* As in store_init_value. */
11012 {
11014 {
11015 /* 5.19 says that a constant expression can include an
11016 lvalue-rvalue conversion applied to "a glvalue of literal type
11017 that refers to a non-volatile temporary object initialized
11018 with a constant expression". Rather than try to communicate
11019 that this VAR_DECL is a temporary, just mark it constexpr. */
11024 }
11027 }
11028 else
11029 /* Create the INIT_EXPR that will initialize the temporary
11030 variable. */
11033 {
11038 else
11039 {
11043 }
11045 /* We must be careful to destroy the temporary only
11046 after its initialization has taken place. If the
11047 initialization throws an exception, then the
11048 destructor should not be run. We cannot simply
11049 transform INIT into something like:
11051 (INIT, ({ CLEANUP_STMT; }))
11053 because emit_local_var always treats the
11054 initializer as a full-expression. Thus, the
11055 destructor would run too early; it would run at the
11056 end of initializing the reference variable, rather
11057 than at the end of the block enclosing the
11058 reference variable.
11060 The solution is to pass back a cleanup expression
11061 which the caller is responsible for attaching to
11062 the statement tree. */
11063 }
11064 else
11065 {
11068 {
11071 tls_aggregates);
11072 else
11074 static_aggregates);
11075 }
11076 else
11077 /* Check whether the dtor is callable. */
11079 }
11080 /* Avoid -Wunused-variable warning (c++/38958). */
11087 }
11089 /* Convert EXPR to the indicated reference TYPE, in a way suitable for
11090 initializing a variable of that TYPE. */
11092 tree
11095 {
11103 /* Get the high-water mark for the CONVERSION_OBSTACK. */
11109 {
11111 {
11120 else
11124 }
11126 }
11129 /* Perform the conversion. */
11132 /* We gave an error in build_user_type_conversion_1. */
11134 else
11137 /* Free all the conversions we allocated. */
11141 }
11143 /* Subroutine of extend_ref_init_temps. Possibly extend one initializer,
11144 which is bound either to a reference or a std::initializer_list. */
11146 static tree
11148 {
11153 {
11157 }
11160 /* Deal with binding to a subobject. */
11166 {
11174 }
11176 }
11178 /* INIT is part of the initializer for DECL. If there are any
11179 reference or initializer lists being initialized, extend their
11180 lifetime to match that of DECL. */
11182 tree
11184 {
11190 else
11191 {
11196 {
11198 {
11199 /* The temporary array underlying a std::initializer_list
11200 is handled like a reference temporary. */
11204 }
11205 else
11206 {
11212 }
11216 }
11217 }
11220 }
11222 /* Returns true iff an initializer for TYPE could contain temporaries that
11223 need to be extended because they are bound to references or
11224 std::initializer_list. */
11226 bool
11228 {
11233 {
11240 }
11242 }
11244 /* Returns true iff TYPE is some variant of std::initializer_list. */
11246 bool
11248 {
11253 /* Look through typedefs. */
11258 }
11260 /* Returns true iff DECL is a list constructor: i.e. a constructor which
11261 will accept an argument list of a single std::initializer_list<T>. */
11263 bool
11265 {
11267 tree arg;
11279 /* There are more non-defaulted parms. */
11283 }