| blob | e4df72ec1a377acd6000faf28f969b9eaed7ca04 |
1 /* Functions related to invoking -*- C++ -*- methods and overloaded functions.
2 Copyright (C) 1987-2021 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 or ck_base, true to indicate that a
96 temporary should be created to hold the result of the
97 conversion. If KIND is ck_ambig or ck_user, true means force
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 or ck_base,
106 true when we are treating an lvalue as an rvalue (12.8p33). If
107 ck_identity, we will be binding a reference directly or decaying to
108 a pointer. */
111 /* Whether check_narrowing should only check TREE_CONSTANTs; used
112 in build_converted_constant_expr. */
114 /* True if this conversion is taking place in a copy-initialization context
115 and we should only consider converting constructors. Only set in
116 ck_base and ck_rvalue. */
118 /* The type of the expression resulting from the conversion. */
119 tree type;
121 /* The next conversion in the chain. Since the conversions are
122 arranged from outermost to innermost, the NEXT conversion will
123 actually be performed before this conversion. This variant is
124 used only when KIND is neither ck_identity, ck_aggr, ck_ambig nor
125 ck_list. Please use the next_conversion function instead
126 of using this field directly. */
128 /* The expression at the beginning of the conversion chain. This
129 variant is used only if KIND is ck_identity, ck_aggr, or ck_ambig.
130 You can use conv_get_original_expr to get this expression. */
131 tree expr;
132 /* The array of conversions for an initializer_list, so this
133 variant is used only when KIN D is ck_list. */
136 /* The function candidate corresponding to this conversion
137 sequence. This field is only used if KIND is ck_user. */
139 };
141 #define CONVERSION_RANK(NODE) \
142 ((NODE)->bad_p ? cr_bad \
143 : (NODE)->ellipsis_p ? cr_ellipsis \
144 : (NODE)->user_conv_p ? cr_user \
145 : (NODE)->rank)
147 #define BAD_CONVERSION_RANK(NODE) \
148 ((NODE)->ellipsis_p ? cr_ellipsis \
149 : (NODE)->user_conv_p ? cr_user \
150 : (NODE)->rank)
159 tsubst_flags_t);
166 tsubst_flags_t);
170 tsubst_flags_t);
190 tsubst_flags_t);
192 tsubst_flags_t);
211 tsubst_flags_t);
219 /* Returns nonzero iff the destructor name specified in NAME matches BASETYPE.
220 NAME can take many forms... */
222 bool
224 {
225 /* Just accept something we've already complained about. */
234 {
240 /* Otherwise lookup the name, it could be an unrelated typedef
241 of the correct type. */
248 }
249 else
250 {
251 /* In the case of:
253 template <class T> struct S { ~S(); };
254 int i;
255 i.~S();
257 NAME will be a class template. */
260 }
263 }
265 /* We want the address of a function or method. We avoid creating a
266 pointer-to-member function. */
268 tree
270 {
273 /* We have to do these by hand to avoid real pointer to member
274 functions. */
276 {
278 {
282 complain);
283 }
285 }
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(). */
340 {
346 }
349 }
351 tree
353 {
354 tree decl;
355 tree result_type;
356 tree fntype;
365 /* An rvalue has no cv-qualifiers. */
376 {
377 /* We invoke build_call directly for several library
378 functions. These may have been declared normally if
379 we're building libgcc, so we can't just check
380 DECL_ARTIFICIAL. */
385 }
391 /* Don't pass empty class objects by value. This is useful
392 for tags in STL, which are used to control overload resolution.
393 We don't need to handle other cases of copying empty classes. */
396 {
400 {
402 /* We're disconnecting the initializer from its target,
403 don't create a temporary. */
408 }
409 }
412 }
414 /* New overloading code. */
421 };
423 /* Information for providing diagnostics about why overloading failed. */
426 rr_none,
427 rr_arity,
428 rr_explicit_conversion,
429 rr_template_conversion,
430 rr_arg_conversion,
431 rr_bad_arg_conversion,
432 rr_template_unification,
433 rr_invalid_copy,
434 rr_inherited_ctor,
435 rr_constraint_failure
436 };
439 /* The index of the argument, 0-based. */
441 /* The actual argument or its type. */
442 tree from;
443 /* The type of the parameter. */
444 tree to_type;
445 /* The location of the argument. */
446 location_t loc;
447 };
452 /* Information about an arity mismatch. */
454 /* The expected number of arguments. */
456 /* The actual number of arguments in the call. */
458 /* Whether the call was a varargs call. */
461 /* Information about an argument conversion mismatch. */
463 /* Same, but for bad argument conversions. */
465 /* Information about template unification failures. These are the
466 parameters passed to fn_type_unification. */
468 tree tmpl;
469 tree explicit_targs;
473 tree return_type;
474 unification_kind_t strict;
477 /* Information about template instantiation failures. These are the
478 parameters passed to instantiate_template. */
480 tree tmpl;
481 tree targs;
484 };
487 /* The FUNCTION_DECL that will be called if this candidate is
488 selected by overload resolution. */
489 tree fn;
490 /* If not NULL_TREE, the first argument to use when calling this
491 function. */
492 tree first_arg;
493 /* The rest of the arguments to use when calling this function. If
494 there are no further arguments this may be NULL or it may be an
495 empty vector. */
497 /* The implicit conversion sequences for each of the arguments to
498 FN. */
500 /* The number of implicit conversion sequences. */
502 /* If FN is a user-defined conversion, the standard conversion
503 sequence from the type returned by FN to the desired destination
504 type. */
507 /* If FN is a member function, the binfo indicating the path used to
508 qualify the name of FN at the call site. This path is used to
509 determine whether or not FN is accessible if it is selected by
510 overload resolution. The DECL_CONTEXT of FN will always be a
511 (possibly improper) base of this binfo. */
512 tree access_path;
513 /* If FN is a non-static member function, the binfo indicating the
514 subobject to which the `this' pointer should be converted if FN
515 is selected by overload resolution. The type pointed to by
516 the `this' pointer must correspond to the most derived class
517 indicated by the CONVERSION_PATH. */
518 tree conversion_path;
519 tree template_decl;
520 tree explicit_targs;
525 /* The flags active in add_candidate. */
530 };
532 /* Returns true iff T is a null pointer constant in the sense of
533 [conv.ptr]. */
535 bool
537 {
540 /* [conv.ptr]
542 A null pointer constant is an integer literal ([lex.icon]) with value
543 zero or a prvalue of type std::nullptr_t. */
548 {
551 /* Core issue 903 says only literal 0 is a null pointer constant. */
558 }
560 {
565 }
568 }
570 /* Returns true iff T is a null member pointer value (4.11). */
572 bool
574 {
584 else
586 }
588 /* Returns nonzero if PARMLIST consists of only default parms,
589 ellipsis, and/or undeduced parameter packs. */
591 bool
593 {
600 }
602 /* Allocate N bytes of memory from the conversion obstack. The memory
603 is zeroed before being returned. */
607 {
610 {
613 }
617 }
619 /* Allocate rejection reasons. */
623 {
628 }
632 {
638 }
642 location_t loc)
643 {
651 }
655 location_t loc)
656 {
664 }
668 {
675 }
679 {
686 }
693 {
700 /* Copy args to our own storage. */
708 }
712 {
714 }
718 {
721 }
725 {
728 }
730 /* Build a constraint failure record. */
734 {
737 }
739 /* Dynamically allocate a conversion. */
743 {
748 }
750 /* Make sure that all memory on the conversion obstack has been
751 freed. */
753 void
755 {
759 }
761 /* Dynamically allocate an array of N conversions. */
765 {
767 }
769 /* True iff the active member of conversion::u for code CODE is NEXT. */
773 {
778 }
782 {
786 /* Only call this function for conversions that use u.next. */
789 /* Note that the caller is responsible for filling in t->cand for
790 user-defined conversions. */
796 {
813 }
819 }
821 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
822 specialization of std::initializer_list<T>, if such a conversion is
823 possible. */
827 {
833 tree val;
835 /* Within a list-initialization we can have more user-defined
836 conversions. */
838 /* But no narrowing conversions. */
841 /* Can't make an array of these types. */
848 {
849 conversion *sub
856 }
864 {
872 }
875 }
877 /* Return the next conversion of the conversion chain (if applicable),
878 or NULL otherwise. Please use this function instead of directly
879 accessing fields of struct conversion. */
883 {
888 }
890 /* Strip to the first ck_user, ck_ambig, ck_list, ck_aggr or ck_identity
891 encountered. */
895 {
901 }
903 /* Subroutine of build_aggr_conv: check whether FROM is a valid aggregate
904 initializer for array type ATYPE. */
906 static bool
908 {
913 {
915 {
920 else
922 complain);
925 }
927 }
933 /* No other valid way to aggregate initialize an array. */
935 }
937 /* Helper for build_aggr_conv. Return true if FIELD is in PSET, or if
938 FIELD has ANON_AGGR_TYPE_P and any initializable field in there recursively
939 is in PSET. */
941 static bool
943 {
949 {
955 }
957 }
959 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
960 aggregate class, if such a conversion is possible. */
964 {
971 /* We already called reshape_init in implicit_conversion. */
973 /* The conversions within the init-list aren't affected by the enclosing
974 context; they're always simple copy-initialization. */
977 /* For designated initializers, verify that each initializer is convertible
978 to corresponding TREE_TYPE (ce->index) and mark those FIELD_DECLs as
979 visited. In the following loop then ignore already visited
980 FIELD_DECLs. */
982 {
985 {
987 {
993 else
995 complain);
999 /* For unions, there should be just one initializer. */
1001 {
1005 }
1007 }
1008 else
1010 }
1011 }
1014 {
1016 tree val;
1022 {
1025 }
1029 /* Value-initialization of reference is ill-formed. */
1031 else
1032 {
1036 }
1040 else
1042 complain);
1049 }
1061 }
1063 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
1064 array type, if such a conversion is possible. */
1068 {
1073 tree val;
1078 /* We might need to propagate the size from the element to the array. */
1083 {
1087 }
1092 {
1093 conversion *sub
1105 }
1114 }
1116 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
1117 complex type, if such a conversion is possible. */
1121 tsubst_flags_t complain)
1122 {
1127 tree val;
1138 {
1139 conversion *sub
1151 }
1160 }
1162 /* Build a representation of the identity conversion from EXPR to
1163 itself. The TYPE should match the type of EXPR, if EXPR is non-NULL. */
1167 {
1175 }
1177 /* Converting from EXPR to TYPE was ambiguous in the sense that there
1178 were multiple user-defined conversions to accomplish the job.
1179 Build a conversion that indicates that ambiguity. */
1183 {
1191 }
1193 tree
1195 {
1199 }
1201 /* Returns the standard conversion path (see [conv]) from type FROM to type
1202 TO, if any. For proper handling of null pointer constants, you must
1203 also pass the expression EXPR to convert from. If C_CAST_P is true,
1204 this conversion is coming from a C-style cast. */
1209 {
1213 tree qualified_to;
1217 {
1220 }
1226 {
1228 {
1234 }
1236 {
1237 /* Necessary for eg, TEMPLATE_ID_EXPRs (c++/50961). */
1240 }
1241 }
1248 {
1251 /* Tell convert_like that we're using the address. */
1254 }
1255 /* Wrapping a ck_rvalue around a class prvalue (as a result of using
1256 obvalue_p) seems odd, since it's already a prvalue, but that's how we
1257 express the copy constructor call required by copy-initialization. */
1259 {
1261 {
1262 tree bitfield_type;
1265 {
1268 }
1269 }
1272 /* Tell convert_like to set LOOKUP_PREFER_RVALUE. */
1274 /* If we're performing copy-initialization, remember to skip
1275 explicit constructors. */
1278 }
1280 /* Allow conversion between `__complex__' data types. */
1282 {
1283 /* The standard conversion sequence to convert FROM to TO is
1284 the standard conversion sequence to perform componentwise
1285 conversion. */
1288 complain);
1294 else
1295 {
1298 }
1301 }
1304 {
1308 }
1310 /* [conv.ptr]
1311 A null pointer constant can be converted to a pointer type; ... A
1312 null pointer constant of integral type can be converted to an
1313 rvalue of type std::nullptr_t. */
1321 {
1322 /* For backwards brain damage compatibility, allow interconversion of
1323 pointers and integers with a pedwarn. */
1326 }
1328 {
1329 /* For backwards brain damage compatibility, allow interconversion of
1330 enums and integers with a pedwarn. */
1333 }
1336 {
1337 tree to_pointee;
1338 tree from_pointee;
1341 {
1345 /* Since this is the target of a pointer, it can't have function
1346 qualifiers, so any TYPE_QUALS must be for attributes const or
1347 noreturn. Strip them. */
1354 }
1355 else
1356 {
1359 }
1363 to_pointee))
1364 ;
1368 {
1370 /* Don't try to apply restrict to void. */
1375 }
1377 {
1384 && (same_type_ignoring_top_level_qualifiers_p
1386 {
1389 }
1390 else
1392 }
1395 /* [conv.ptr]
1397 An rvalue of type "pointer to cv D," where D is a
1398 class type, can be converted to an rvalue of type
1399 "pointer to cv B," where B is a base class (clause
1400 _class.derived_) of D. If B is an inaccessible
1401 (clause _class.access_) or ambiguous
1402 (_class.member.lookup_) base class of D, a program
1403 that necessitates this conversion is ill-formed.
1404 Therefore, we use DERIVED_FROM_P, and do not check
1405 access or uniqueness. */
1407 {
1408 from_pointee
1414 }
1419 /* In a C-style cast, we ignore CV-qualification because we
1420 are allowed to perform a static_cast followed by a
1421 const_cast. */
1426 /* converting from string constant to char *. */
1430 /* Allow conversions among compatible ObjC pointer types (base
1431 conversions have been already handled above). */
1436 {
1439 }
1440 else
1444 }
1446 {
1452 /* If FBASE and TBASE are equivalent but incomplete, DERIVED_FROM_P
1453 yields false. But a pointer to member of incomplete class is OK. */
1462 else
1466 {
1468 tbase,
1474 }
1477 }
1479 {
1480 /* [conv.bool]
1482 A prvalue of arithmetic, unscoped enumeration, pointer, or pointer
1483 to member type can be converted to a prvalue of type bool. ...
1484 For direct-initialization (8.5 [dcl.init]), a prvalue of type
1485 std::nullptr_t can be converted to a prvalue of type bool; */
1491 {
1504 }
1507 }
1508 /* We don't check for ENUMERAL_TYPE here because there are no standard
1509 conversions to enum type. */
1510 /* As an extension, allow conversion to complex type. */
1512 {
1518 /* If we're parsing an enum with no fixed underlying type, we're
1519 dealing with an incomplete type, which renders the conversion
1520 ill-formed. */
1531 /* Give this a better rank if it's a promotion.
1533 To handle CWG 1601, also bump the rank if we are converting
1534 an enumeration with a fixed underlying type to the underlying
1535 type. */
1540 }
1546 {
1550 /* The derived-to-base conversion indicates the initialization
1551 of a parameter with base type from an object of a derived
1552 type. A temporary object is created to hold the result of
1553 the conversion unless we're binding directly to a reference. */
1556 /* Tell convert_like to set LOOKUP_PREFER_RVALUE. */
1558 /* If we're performing copy-initialization, remember to skip
1559 explicit constructors. */
1562 }
1563 else
1570 }
1572 /* Returns nonzero if T1 is reference-related to T2. */
1574 bool
1576 {
1583 /* [dcl.init.ref]
1585 Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
1586 to "cv2 T2" if T1 is similar to T2, or T1 is a base class of T2. */
1590 }
1592 /* Returns nonzero if T1 is reference-compatible with T2. */
1594 bool
1596 {
1597 /* [dcl.init.ref]
1599 "cv1 T1" is reference compatible with "cv2 T2" if
1600 a prvalue of type "pointer to cv2 T2" can be converted to the type
1601 "pointer to cv1 T1" via a standard conversion sequence. */
1609 }
1611 /* Return true if converting FROM to TO would involve a qualification
1612 conversion. */
1614 static bool
1616 {
1617 /* If we're not convering a pointer to another one, we won't get
1618 a qualification conversion. */
1630 }
1632 /* A reference of the indicated TYPE is being bound directly to the
1633 expression represented by the implicit conversion sequence CONV.
1634 Return a conversion sequence for this binding. */
1638 {
1639 tree t;
1647 /* Mark the identity conv as to not decay to rvalue. */
1650 /* [over.ics.rank]
1652 When a parameter of reference type binds directly
1653 (_dcl.init.ref_) to an argument expression, the implicit
1654 conversion sequence is the identity conversion, unless the
1655 argument expression has a type that is a derived class of the
1656 parameter type, in which case the implicit conversion sequence is
1657 a derived-to-base Conversion.
1659 If the parameter binds directly to the result of applying a
1660 conversion function to the argument expression, the implicit
1661 conversion sequence is a user-defined conversion sequence
1662 (_over.ics.user_), with the second standard conversion sequence
1663 either an identity conversion or, if the conversion function
1664 returns an entity of a type that is a derived class of the
1665 parameter type, a derived-to-base conversion. */
1667 {
1668 /* Represent the derived-to-base conversion. */
1670 /* We will actually be binding to the base-class subobject in
1671 the derived class, so we mark this conversion appropriately.
1672 That way, convert_like knows not to generate a temporary. */
1674 }
1676 /* Represent the qualification conversion. After DR 2352
1677 #1 and #2 were indistinguishable conversion sequences:
1679 void f(int*); // #1
1680 void f(const int* const &); // #2
1681 void g(int* p) { f(p); }
1683 because the types "int *" and "const int *const" are
1684 reference-related and we were binding both directly and they
1685 had the same rank. To break it up, we add a ck_qual under the
1686 ck_ref_bind so that conversion sequence ranking chooses #1. */
1690 }
1692 /* Returns the conversion path from type FROM to reference type TO for
1693 purposes of reference binding. For lvalue binding, either pass a
1694 reference type to FROM or an lvalue expression to EXPR. If the
1695 reference will be bound to a temporary, NEED_TEMPORARY_P is set for
1696 the conversion returned. If C_CAST_P is true, this
1697 conversion is coming from a C-style cast. */
1701 tsubst_flags_t complain)
1702 {
1706 tree tfrom;
1709 cp_lvalue_kind gl_kind;
1713 {
1718 }
1722 {
1724 /* DR 1288: Otherwise, if the initializer list has a single element
1725 of type E and ... [T's] referenced type is reference-related to E,
1726 the object or reference is initialized from that element...
1728 ??? With P0388R4, we should bind 't' directly to U{}:
1729 using U = A[2];
1730 A (&&t)[] = {U{}};
1731 because A[] and A[2] are reference-related. But we don't do it
1732 because grok_reference_init has deduced the array size (to 1), and
1733 A[1] and A[2] aren't reference-related. */
1736 {
1742 {
1746 }
1747 }
1748 /* Otherwise, if T is a reference type, a prvalue temporary of the type
1749 referenced by T is copy-list-initialized, and the reference is bound
1750 to that temporary. */
1752 skip:;
1753 }
1756 {
1761 else
1763 }
1769 else
1772 /* Don't allow a class prvalue when LOOKUP_NO_TEMP_BIND. */
1777 /* Same mask as real_lvalue_p. */
1784 /* Figure out whether or not the types are reference-related and
1785 reference compatible. We have to do this after stripping
1786 references from FROM. */
1788 /* If this is a C cast, first convert to an appropriately qualified
1789 type, so that we can later do a const_cast to the desired type. */
1795 /* Directly bind reference when target expression's type is compatible with
1796 the reference and expression is an lvalue. In DR391, the wording in
1797 [8.5.3/5 dcl.init.ref] is changed to also require direct bindings for
1798 const and rvalue references to rvalues of compatible class type.
1799 We should also do direct bindings for non-class xvalues. */
1801 {
1802 /* [dcl.init.ref]
1804 If the initializer expression
1806 -- is an lvalue (but not an lvalue for a bit-field), and "cv1 T1"
1807 is reference-compatible with "cv2 T2,"
1809 the reference is bound directly to the initializer expression
1810 lvalue.
1812 [...]
1813 If the initializer expression is an rvalue, with T2 a class type,
1814 and "cv1 T1" is reference-compatible with "cv2 T2", the reference
1815 is bound to the object represented by the rvalue or to a sub-object
1816 within that object. */
1822 /* Handle rvalue reference to function properly. */
1823 conv->rvaluedness_matches_p
1825 else
1826 conv->rvaluedness_matches_p
1831 /* For the purposes of overload resolution, we ignore the fact
1832 this expression is a bitfield or packed field. (In particular,
1833 [over.ics.ref] says specifically that a function with a
1834 non-const reference parameter is viable even if the
1835 argument is a bitfield.)
1837 However, when we actually call the function we must create
1838 a temporary to which to bind the reference. If the
1839 reference is volatile, or isn't const, then we cannot make
1840 a temporary, so we just issue an error when the conversion
1841 actually occurs. */
1844 /* Don't allow binding of lvalues (other than function lvalues) to
1845 rvalue references. */
1850 /* Nor the reverse. */
1852 /* Unless it's really an lvalue. */
1864 }
1865 /* [class.conv.fct] A conversion function is never used to convert a
1866 (possibly cv-qualified) object to the (possibly cv-qualified) same
1867 object type (or a reference to it), to a (possibly cv-qualified) base
1868 class of that type (or a reference to it).... */
1871 {
1872 /* [dcl.init.ref]
1874 If the initializer expression
1876 -- has a class type (i.e., T2 is a class type) can be
1877 implicitly converted to an lvalue of type "cv3 T3," where
1878 "cv1 T1" is reference-compatible with "cv3 T3". (this
1879 conversion is selected by enumerating the applicable
1880 conversion functions (_over.match.ref_) and choosing the
1881 best one through overload resolution. (_over.match_).
1883 the reference is bound to the lvalue result of the conversion
1884 in the second case. */
1886 complain);
1889 }
1891 /* From this point on, we conceptually need temporaries, even if we
1892 elide them. Only the cases above are "direct bindings". */
1896 /* [over.ics.rank]
1898 When a parameter of reference type is not bound directly to an
1899 argument expression, the conversion sequence is the one required
1900 to convert the argument expression to the underlying type of the
1901 reference according to _over.best.ics_. Conceptually, this
1902 conversion sequence corresponds to copy-initializing a temporary
1903 of the underlying type with the argument expression. Any
1904 difference in top-level cv-qualification is subsumed by the
1905 initialization itself and does not constitute a conversion. */
1907 /* [dcl.init.ref]
1909 Otherwise, the reference shall be an lvalue reference to a
1910 non-volatile const type, or the reference shall be an rvalue
1911 reference.
1913 We try below to treat this as a bad conversion to improve diagnostics,
1914 but if TO is an incomplete class, we need to reject this conversion
1915 now to avoid unnecessary instantiation. */
1920 /* We're generating a temporary now, but don't bind any more in the
1921 conversion (specifically, don't slice the temporary returned by a
1922 conversion operator). */
1925 /* Core issue 899: When [copy-]initializing a temporary to be bound
1926 to the first parameter of a copy constructor (12.8) called with
1927 a single argument in the context of direct-initialization,
1928 explicit conversion functions are also considered.
1930 So don't set LOOKUP_ONLYCONVERTING in that case. */
1941 {
1943 /* Remember this was copy-list-initialization. */
1946 /* If initializing the temporary used a conversion function,
1947 recalculate the second conversion sequence. */
1951 {
1953 /* A prvalue of non-class type is cv-unqualified. */
1957 conversion *new_second
1963 }
1964 }
1967 /* This reference binding, unlike those above, requires the
1968 creation of a temporary. */
1972 /* [dcl.init.ref]
1974 Otherwise, the reference shall be an lvalue reference to a
1975 non-volatile const type, or the reference shall be an rvalue
1976 reference. */
1980 /* [dcl.init.ref]
1982 Otherwise, a temporary of type "cv1 T1" is created and
1983 initialized from the initializer expression using the rules for a
1984 non-reference copy initialization. If T1 is reference-related to
1985 T2, cv1 must be the same cv-qualification as, or greater
1986 cv-qualification than, cv2; otherwise, the program is ill-formed. */
1991 }
1993 /* Most of the implementation of implicit_conversion, with the same
1994 parameters. */
1999 {
2006 /* Other flags only apply to the primary function in overload
2007 resolution, or after we've chosen one. */
2012 /* FIXME: actually we don't want warnings either, but we can't just
2013 have 'complain &= ~(tf_warning|tf_error)' because it would cause
2014 the regression of, eg, g++.old-deja/g++.benjamin/16077.C.
2015 We really ought not to issue that warning until we've committed
2016 to that conversion. */
2019 /* Call reshape_init early to remove redundant braces. */
2024 {
2029 }
2033 else
2040 {
2044 /* As an extension, allow list-initialization of _Complex. */
2047 {
2051 }
2053 /* Allow conversion from an initializer-list with one element to a
2054 scalar type. */
2056 {
2058 tree elt;
2064 else
2070 {
2073 /* Too many levels of braces, i.e. '{{1}}'. */
2076 }
2077 }
2080 }
2086 {
2096 {
2101 {
2102 /* "If C is not an initializer-list constructor and the
2103 initializer list has a single element of type cv U, where U is
2104 X or a class derived from X, the implicit conversion sequence
2105 has Exact Match rank if U is X, or Conversion rank if U is
2106 derived from X." */
2112 }
2114 }
2116 /* We used to try to bind a reference to a temporary here, but that
2117 is now handled after the recursive call to this function at the end
2118 of reference_binding. */
2120 }
2123 }
2125 /* Returns the implicit conversion sequence (see [over.ics]) from type
2126 FROM to type TO. The optional expression EXPR may affect the
2127 conversion. FLAGS are the usual overloading flags. If C_CAST_P is
2128 true, this conversion is coming from a C-style cast. */
2133 {
2143 }
2145 /* Like implicit_conversion, but return NULL if the conversion is bad.
2147 This is not static so that check_non_deducible_conversion can call it within
2148 add_template_candidate_real as part of overload resolution; it should not be
2149 called outside of overload resolution. */
2151 conversion *
2154 {
2160 }
2162 /* Add a new entry to the list of candidates. Used by the add_*_candidate
2163 functions. ARGS will not be changed until a single candidate is
2164 selected. */
2173 {
2191 /* Swap the conversions for comparison in joust; we'll swap them back
2192 before build_over_call. */
2196 }
2198 /* Return the number of remaining arguments in the parameter list
2199 beginning with ARG. */
2201 int
2203 {
2208 n++;
2211 }
2213 /* [over.match.copy]: When initializing a temporary object (12.2) to be bound
2214 to the first parameter of a constructor where the parameter is of type
2215 "reference to possibly cv-qualified T" and the constructor is called with a
2216 single argument in the context of direct-initialization of an object of type
2217 "cv2 T", explicit conversion functions are also considered.
2219 So set LOOKUP_COPY_PARM to let reference_binding know that
2220 it's being called in that context. */
2222 int
2224 {
2226 tree t;
2229 && (same_type_ignoring_top_level_qualifiers_p
2231 {
2237 }
2238 else
2242 }
2244 /* Create an overload candidate for the function or method FN called
2245 with the argument list FIRST_ARG/ARGS and add it to CANDIDATES.
2246 FLAGS is passed on to implicit_conversion.
2248 This does not change ARGS.
2250 CTYPE, if non-NULL, is the type we want to pretend this function
2251 comes from for purposes of overload resolution. */
2259 tsubst_flags_t complain)
2260 {
2263 tree parmnode;
2269 /* The `this', `in_chrg' and VTT arguments to constructors are not
2270 considered in overload resolution. */
2272 {
2274 /* Bring back parameters omitted from an inherited ctor. */
2276 else
2280 {
2283 }
2284 }
2285 else
2292 /* 13.3.2 - Viable functions [over.match.viable]
2293 First, to be a viable function, a candidate function shall have enough
2294 parameters to agree in number with the arguments in the list.
2296 We need to check this first; otherwise, checking the ICSes might cause
2297 us to produce an ill-formed template instantiation. */
2301 {
2305 }
2309 {
2313 }
2315 /* An inherited constructor (12.6.3 [class.inhctor.init]) that has a first
2316 parameter of type "reference to cv C" (including such a constructor
2317 instantiated from a template) is excluded from the set of candidate
2318 functions when used to construct an object of type D with an argument list
2319 containing a single argument if C is reference-related to D. */
2321 && flag_new_inheriting_ctors
2323 {
2329 {
2332 }
2333 }
2335 /* Second, for a function to be viable, its constraints must be
2336 satisfied. */
2338 {
2341 }
2343 /* When looking for a function from a subobject from an implicit
2344 copy/move constructor/operator=, don't consider anything that takes (a
2345 reference to) an unrelated type. See c++/44909 and core 1092. */
2347 {
2353 else
2356 {
2359 ctype))
2361 }
2363 /* This only applies at the top level. */
2365 }
2370 /* Third, for F to be a viable function, there shall exist for each
2371 argument an implicit conversion sequence that converts that argument
2372 to the corresponding parameter of F. */
2377 {
2379 tree arg;
2387 {
2388 /* Already set during deduction. */
2391 }
2395 else
2404 {
2409 /* The type of the implicit object parameter ('this') for
2410 overload resolution is not always the same as for the
2411 function itself; conversion functions are considered to
2412 be members of the class being converted, and functions
2413 introduced by a using-declaration are considered to be
2414 members of the class that uses them.
2416 Since build_over_call ignores the ICS for the `this'
2417 parameter, we can just change the parm type. */
2419 {
2420 parmtype = cp_build_qualified_type
2423 {
2424 /* If the function has a ref-qualifier, the implicit
2425 object parameter has reference type. */
2428 /* The special handling of 'this' conversions in compare_ics
2429 does not apply if there is a ref-qualifier. */
2431 }
2432 else
2433 {
2435 /* We don't use build_this here because we don't want to
2436 capture the object argument until we've chosen a
2437 non-static member function. */
2440 }
2441 }
2448 }
2449 else
2450 {
2454 }
2461 {
2466 }
2469 {
2474 }
2475 }
2477 out:
2480 }
2482 /* Create an overload candidate for the conversion function FN which will
2483 be invoked for expression OBJ, producing a pointer-to-function which
2484 will in turn be called with the argument list FIRST_ARG/ARGLIST,
2485 and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
2486 passed on to implicit_conversion.
2488 Actually, we don't really care about FN; we care about the type it
2489 converts to. There may be multiple conversion functions that will
2490 convert to that type, and we rely on build_user_type_conversion_1 to
2491 choose the best one; so when we create our candidate, we record the type
2492 instead of the function. */
2498 tsubst_flags_t complain)
2499 {
2517 /* Don't bother looking up the same type twice. */
2522 {
2528 else
2533 {
2536 /* Leave the 'cand' field null; we'll figure out the conversion in
2537 convert_like if this candidate is chosen. */
2539 }
2543 {
2547 }
2548 else
2549 {
2553 }
2560 {
2564 }
2571 }
2575 {
2579 }
2583 }
2585 static void
2589 {
2603 /* TRUTH_*_EXPR do "contextual conversion to bool", which means explicit
2604 conversion ops are allowed. We handle that here by just checking for
2605 boolean_type_node because other operators don't ask for it. COND_EXPR
2606 also does contextual conversion to bool for the first operand, but we
2607 handle that in build_conditional_expr, and type1 here is operand 2. */
2612 {
2616 {
2618 /* We need something for printing the candidate. */
2622 }
2624 {
2629 }
2631 }
2633 /* For COND_EXPR we rearranged the arguments; undo that now. */
2635 {
2640 complain);
2643 else
2644 {
2647 boolean_type_node,
2649 }
2650 }
2657 }
2659 static bool
2661 {
2663 }
2665 /* Returns nonzero if TYPE is a promoted arithmetic type. */
2667 static bool
2669 {
2670 /* [over.built]
2672 In this section, the term promoted integral type is used to refer
2673 to those integral types which are preserved by integral promotion
2674 (including e.g. int and long but excluding e.g. char).
2675 Similarly, the term promoted arithmetic type refers to promoted
2676 integral types plus floating types. */
2680 }
2682 /* Create any builtin operator overload candidates for the operator in
2683 question given the converted operand types TYPE1 and TYPE2. The other
2684 args are passed through from add_builtin_candidates to
2685 build_builtin_candidate.
2687 TYPE1 and TYPE2 may not be permissible, and we must filter them.
2688 If CODE is requires candidates operands of the same type of the kind
2689 of which TYPE1 and TYPE2 are, we add both candidates
2690 CODE (TYPE1, TYPE1) and CODE (TYPE2, TYPE2). */
2692 static void
2697 {
2699 {
2707 }
2710 {
2712 /* 4 For every pair (T, VQ), where T is an arithmetic type other than bool,
2713 and VQ is either volatile or empty, there exist candidate operator
2714 functions of the form
2715 VQ T& operator++(VQ T&);
2716 T operator++(VQ T&, int);
2717 5 For every pair (T, VQ), where T is an arithmetic type other than bool,
2718 and VQ is either volatile or empty, there exist candidate operator
2719 functions of the form
2720 VQ T& operator--(VQ T&);
2721 T operator--(VQ T&, int);
2722 6 For every pair (T, VQ), where T is a cv-qualified or cv-unqualified object
2723 type, and VQ is either volatile or empty, there exist candidate operator
2724 functions of the form
2725 T*VQ& operator++(T*VQ&);
2726 T*VQ& operator--(T*VQ&);
2727 T* operator++(T*VQ&, int);
2728 T* operator--(T*VQ&, int); */
2734 /* FALLTHRU */
2737 /* P0002R1, Remove deprecated operator++(bool) added "other than bool"
2738 to p4. */
2742 {
2745 }
2748 /* 7 For every cv-qualified or cv-unqualified object type T, there
2749 exist candidate operator functions of the form
2751 T& operator*(T*);
2754 8 For every function type T that does not have cv-qualifiers or
2755 a ref-qualifier, there exist candidate operator functions of the form
2756 T& operator*(T*); */
2765 /* 9 For every type T, there exist candidate operator functions of the form
2766 T* operator+(T*);
2768 10 For every floating-point or promoted integral type T, there exist
2769 candidate operator functions of the form
2770 T operator+(T);
2771 T operator-(T); */
2776 /* FALLTHRU */
2782 /* 11 For every promoted integral type T, there exist candidate operator
2783 functions of the form
2784 T operator~(T); */
2791 /* 12 For every quintuple (C1, C2, T, CV1, CV2), where C2 is a class type, C1
2792 is the same type as C2 or is a derived class of C2, and T is an object
2793 type or a function type there exist candidate operator functions of the
2794 form
2795 CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
2796 where CV12 is the union of CV1 and CV2. */
2800 {
2808 }
2811 /* 13 For every pair of types L and R, where each of L and R is a floating-point
2812 or promoted integral type, there exist candidate operator functions of the
2813 form
2814 LR operator*(L, R);
2815 LR operator/(L, R);
2816 LR operator+(L, R);
2817 LR operator-(L, R);
2818 bool operator<(L, R);
2819 bool operator>(L, R);
2820 bool operator<=(L, R);
2821 bool operator>=(L, R);
2822 bool operator==(L, R);
2823 bool operator!=(L, R);
2824 where LR is the result of the usual arithmetic conversions between
2825 types L and R.
2827 14 For every integral type T there exists a candidate operator function of
2828 the form
2830 std::strong_ordering operator<=>(T, T);
2832 15 For every pair of floating-point types L and R, there exists a candidate
2833 operator function of the form
2835 std::partial_ordering operator<=>(L, R);
2837 16 For every cv-qualified or cv-unqualified object type T there exist
2838 candidate operator functions of the form
2839 T* operator+(T*, std::ptrdiff_t);
2840 T& operator[](T*, std::ptrdiff_t);
2841 T* operator-(T*, std::ptrdiff_t);
2842 T* operator+(std::ptrdiff_t, T*);
2843 T& operator[](std::ptrdiff_t, T*);
2845 17 For every T, where T is a pointer to object type, there exist candidate
2846 operator functions of the form
2847 std::ptrdiff_t operator-(T, T);
2849 18 For every T, where T is an enumeration type or a pointer type, there
2850 exist candidate operator functions of the form
2851 bool operator<(T, T);
2852 bool operator>(T, T);
2853 bool operator<=(T, T);
2854 bool operator>=(T, T);
2855 bool operator==(T, T);
2856 bool operator!=(T, T);
2857 R operator<=>(T, T);
2859 where R is the result type specified in [expr.spaceship].
2861 19 For every T, where T is a pointer-to-member type or std::nullptr_t,
2862 there exist candidate operator functions of the form
2863 bool operator==(T, T);
2864 bool operator!=(T, T); */
2871 {
2874 }
2875 /* FALLTHRU */
2882 /* This isn't exactly what's specified above for operator<=>, but it's
2883 close enough. In particular, we don't care about the return type
2884 specified above; it doesn't participate in overload resolution and it
2885 doesn't affect the semantics of the built-in operator. */
2895 {
2898 }
2900 {
2903 }
2904 /* Fall through. */
2920 {
2923 }
2926 {
2929 }
2935 /* FALLTHRU */
2938 {
2941 }
2943 {
2946 }
2949 /* 18For every pair of promoted integral types L and R, there exist candi-
2950 date operator functions of the form
2951 LR operator%(L, R);
2952 LR operator&(L, R);
2953 LR operator^(L, R);
2954 LR operator|(L, R);
2955 L operator<<(L, R);
2956 L operator>>(L, R);
2957 where LR is the result of the usual arithmetic conversions between
2958 types L and R. */
2966 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2970 /* 19For every triple L, VQ, R), where L is an arithmetic or enumeration
2971 type, VQ is either volatile or empty, and R is a promoted arithmetic
2972 type, there exist candidate operator functions of the form
2973 VQ L& operator=(VQ L&, R);
2974 VQ L& operator*=(VQ L&, R);
2975 VQ L& operator/=(VQ L&, R);
2976 VQ L& operator+=(VQ L&, R);
2977 VQ L& operator-=(VQ L&, R);
2979 20For every pair T, VQ), where T is any type and VQ is either volatile
2980 or empty, there exist candidate operator functions of the form
2981 T*VQ& operator=(T*VQ&, T*);
2983 21For every pair T, VQ), where T is a pointer to member type and VQ is
2984 either volatile or empty, there exist candidate operator functions of
2985 the form
2986 VQ T& operator=(VQ T&, T);
2988 22For every triple T, VQ, I), where T is a cv-qualified or cv-
2989 unqualified complete object type, VQ is either volatile or empty, and
2990 I is a promoted integral type, there exist candidate operator func-
2991 tions of the form
2992 T*VQ& operator+=(T*VQ&, I);
2993 T*VQ& operator-=(T*VQ&, I);
2995 23For every triple L, VQ, R), where L is an integral or enumeration
2996 type, VQ is either volatile or empty, and R is a promoted integral
2997 type, there exist candidate operator functions of the form
2999 VQ L& operator%=(VQ L&, R);
3000 VQ L& operator<<=(VQ L&, R);
3001 VQ L& operator>>=(VQ L&, R);
3002 VQ L& operator&=(VQ L&, R);
3003 VQ L& operator^=(VQ L&, R);
3004 VQ L& operator|=(VQ L&, R); */
3008 {
3012 {
3015 }
3016 /* FALLTHRU */
3029 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
3042 {
3045 }
3050 }
3055 /* [over.built]
3057 For every pair of promoted arithmetic types L and R, there
3058 exist candidate operator functions of the form
3060 LR operator?(bool, L, R);
3062 where LR is the result of the usual arithmetic conversions
3063 between types L and R.
3065 For every type T, where T is a pointer or pointer-to-member
3066 type, there exist candidate operator functions of the form T
3067 operator?(bool, T, T); */
3071 /* That's OK. */
3074 /* Otherwise, the types should be pointers. */
3078 /* We don't check that the two types are the same; the logic
3079 below will actually create two candidates; one in which both
3080 parameter types are TYPE1, and one in which both parameter
3081 types are TYPE2. */
3092 }
3094 /* Make sure we don't create builtin candidates with dependent types. */
3098 {
3099 /* Try to recover if one of the types is non-dependent. But if
3100 there's only one type, there's nothing we can do. */
3103 /* And we lose if both are dependent. */
3106 /* Or if they have different forms. */
3114 }
3116 /* If we're dealing with two pointer types or two enumeral types,
3117 we need candidates for both of them. */
3126 {
3128 {
3131 error_mark_node,
3132 error_mark_node,
3133 CPO_CONVERSION,
3134 tf_none);
3136 {
3137 build_builtin_candidate
3141 }
3142 }
3144 build_builtin_candidate
3146 build_builtin_candidate
3149 }
3151 build_builtin_candidate
3153 }
3155 tree
3157 {
3163 }
3165 /* There are three conditions of builtin candidates:
3167 1) bool-taking candidates. These are the same regardless of the input.
3168 2) pointer-pair taking candidates. These are generated for each type
3169 one of the input types converts to.
3170 3) arithmetic candidates. According to the standard, we should generate
3171 all of these, but I'm trying not to...
3173 Here we generate a superset of the possible candidates for this particular
3174 case. That is a subset of the full set the standard defines, plus some
3175 other cases which the standard disallows. add_builtin_candidate will
3176 filter out the invalid set. */
3178 static void
3183 {
3187 /* TYPES[i] is the set of possible builtin-operator parameter types
3188 we will consider for the Ith argument. */
3195 {
3198 else
3200 }
3203 {
3204 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
3205 and VQ is either volatile or empty, there exist candidate operator
3206 functions of the form
3207 VQ T& operator++(VQ T&); */
3217 /* 24There also exist candidate operator functions of the form
3218 bool operator!(bool);
3219 bool operator&&(bool, bool);
3220 bool operator||(bool, bool); */
3223 build_builtin_candidate
3230 build_builtin_candidate
3250 /* Fall through. */
3254 }
3262 {
3264 {
3265 tree convs;
3273 {
3278 }
3284 {
3297 {
3303 }
3307 }
3308 }
3309 else
3310 {
3315 {
3321 }
3323 }
3324 }
3326 /* Run through the possible parameter types of both arguments,
3327 creating candidates with those parameter types. */
3329 {
3331 tree u;
3335 add_builtin_candidate
3338 else
3339 add_builtin_candidate
3342 }
3346 }
3349 /* If TMPL can be successfully instantiated as indicated by
3350 EXPLICIT_TARGS and ARGLIST, adds the instantiation to CANDIDATES.
3352 TMPL is the template. EXPLICIT_TARGS are any explicit template
3353 arguments. ARGLIST is the arguments provided at the call-site.
3354 This does not change ARGLIST. The RETURN_TYPE is the desired type
3355 for conversion operators. If OBJ is NULL_TREE, FLAGS and CTYPE are
3356 as for add_function_candidate. If an OBJ is supplied, FLAGS and
3357 CTYPE are ignored, and OBJ is as for add_conv_candidate. */
3365 tsubst_flags_t complain)
3366 {
3376 tree arg;
3378 tree fn;
3383 /* We don't do deduction on the in-charge parameter, the VTT
3384 parameter or 'this'. */
3386 {
3390 /* We're deducing for a call to the result of a template conversion
3392 else
3394 }
3399 {
3402 else
3404 }
3412 {
3413 /* 12.8/6 says, "A declaration of a constructor for a class X is
3414 ill-formed if its first parameter is of type (optionally cv-qualified)
3415 X and either there are no other parameters or else all other
3416 parameters have default arguments. A member function template is never
3417 instantiated to produce such a constructor signature."
3419 So if we're trying to copy an object of the containing class, don't
3420 consider a template constructor that has a first parameter type that
3421 is just a template parameter, as we would deduce a signature that we
3422 would then reject in the code below. */
3424 {
3429 {
3433 }
3434 }
3435 }
3442 {
3445 }
3449 {
3452 }
3459 args_without_in_chrg,
3460 nargs_without_in_chrg,
3465 {
3466 /* Don't repeat unification later if it already resulted in errors. */
3470 nargs_without_in_chrg,
3472 else
3475 }
3477 /* Now the explicit specifier might have been deduced; check if this
3478 declaration is explicit. If it is and we're ignoring non-converting
3479 constructors, don't add this function to the set of candidates. */
3484 {
3487 ctype))
3488 {
3489 /* We're trying to produce a constructor with a prohibited signature,
3490 as discussed above; handle here any cases we didn't catch then,
3491 such as X(X<T>). */
3494 }
3495 }
3498 /* Aha, this is a conversion function. */
3501 else
3506 /* This situation can occur if a member template of a template
3507 class is specialized. Then, instantiate_template might return
3508 an instantiation of the specialization, in which case the
3509 DECL_TI_TEMPLATE field will point at the original
3510 specialization. For example:
3512 template <class T> struct S { template <class U> void f(U);
3513 template <> void f(int) {}; };
3514 S<double> sd;
3515 sd.f(3);
3517 Here, TMPL will be template <class U> S<double>::f(U).
3518 And, instantiate template will give us the specialization
3519 template <> S<double>::f(int). But, the DECL_TI_TEMPLATE field
3520 for this will point at template <class T> template <> S<T>::f(int),
3521 so that we can find the definition. For the purposes of
3522 overload resolution, however, we want the original TMPL. */
3524 else
3529 fail:
3532 }
3541 {
3542 return
3547 }
3549 /* Create an overload candidate for the conversion function template TMPL,
3550 returning RETURN_TYPE, which will be invoked for expression OBJ to produce a
3551 pointer-to-function which will in turn be called with the argument list
3552 ARGLIST, and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
3553 passed on to implicit_conversion. */
3557 tree obj,
3561 {
3562 /* Making this work broke PR 71117 and 85118, so until the committee resolves
3563 core issue 2189, let's disable this candidate if there are any call
3564 operators. */
3568 return
3572 complain);
3573 }
3575 /* The CANDS are the set of candidates that were considered for
3576 overload resolution. Return the set of viable candidates, or CANDS
3577 if none are viable. If any of the candidates were viable, set
3578 *ANY_VIABLE_P to true. STRICT_P is true if a candidate should be
3579 considered viable only if it is strictly viable. */
3585 {
3591 /* Be strict inside templates, since build_over_call won't actually
3592 do the conversions to get pedwarns. */
3602 {
3606 {
3607 /* Be strict in the presence of a viable candidate. Also if
3608 there are template candidates, so that we get deduction errors
3609 for them instead of silently preferring a bad conversion. */
3612 {
3613 /* Put any spliced near matches back onto the main list so
3614 that we see them if there is no strict match. */
3620 }
3621 }
3624 {
3632 }
3633 else
3635 }
3638 }
3640 static bool
3642 {
3647 }
3649 /* OBJ is being used in an expression like "OBJ.f (...)". In other
3650 words, it is about to become the "this" pointer for a member
3651 function call. Take the address of the object. */
3653 static tree
3655 {
3656 /* In a template, we are only concerned about the type of the
3657 expression, so we can take a shortcut. */
3662 }
3664 /* Returns true iff functions are equivalent. Equivalent functions are
3665 not '==' only if one is a function-local extern function or if
3666 both are extern "C". */
3670 {
3679 }
3681 /* Print information about a candidate FN being rejected due to INFO. */
3683 static void
3685 tree fn)
3686 {
3691 {
3692 /* Conversion of implicit `this' argument failed. */
3694 /* A bad conversion for 'this' must be discarding cv-quals. */
3697 from);
3698 else
3702 }
3704 {
3709 tf_warning_or_error);
3710 }
3712 /* Conversion of conversion function return value failed. */
3715 else
3716 {
3721 }
3722 }
3724 /* Print information about a candidate with WANT parameters and we found
3725 HAVE. */
3727 static void
3729 {
3734 }
3736 /* Print information about one overload candidate CANDIDATE. MSGSTR
3737 is the text to print before the candidate itself.
3739 NOTE: Unlike most diagnostic functions in GCC, MSGSTR is expected
3740 to have been run through gettext by the caller. This wart makes
3741 life simpler in print_z_candidates and for the translators. */
3743 static void
3746 {
3756 {
3767 else
3770 }
3781 else
3784 {
3787 }
3788 /* Give the user some information about why this candidate failed. */
3790 {
3794 {
3807 "cannot be converted to %qT with a qualification "
3813 "conversion function specialization to %qT is not an "
3818 /* We use template_unification_error_rejection if unification caused
3819 actual non-SFINAE errors, in which case we don't need to repeat
3820 them here. */
3822 {
3826 }
3827 /* Re-run template unification with diagnostics. */
3831 (make_tree_vec
3842 " a constructor taking a single argument of its own "
3850 "initialization from an expression of the same or derived "
3855 /* This candidate didn't have any issues or we failed to
3856 handle a particular code. Either way... */
3858 }
3859 }
3860 }
3862 static void
3864 {
3871 /* Remove non-viable deleted candidates. */
3874 {
3879 else
3881 }
3882 /* ...if there are any non-deleted ones. */
3886 /* There may be duplicates in the set of candidates. We put off
3887 checking this condition as long as possible, since we have no way
3888 to eliminate duplicates from a set of functions in less than n^2
3889 time. Now we are about to emit an error message, so it is more
3890 permissible to go slowly. */
3892 {
3894 /* Skip builtin candidates and conversion functions. */
3899 {
3903 else
3905 }
3906 }
3910 }
3912 /* USER_SEQ is a user-defined conversion sequence, beginning with a
3913 USER_CONV. STD_SEQ is the standard conversion sequence applied to
3914 the result of the conversion function to convert it to the final
3915 desired type. Merge the two sequences into a single sequence,
3916 and return the merged sequence. */
3920 {
3926 /* Find the end of the second conversion sequence. */
3928 {
3929 /* The entire sequence is a user-conversion sequence. */
3933 }
3936 /* We're binding a reference directly to the result of the conversion.
3937 build_user_type_conversion_1 stripped the REFERENCE_TYPE from the return
3938 type, but we want it back. */
3941 /* Replace the identity conversion with the user conversion
3942 sequence. */
3946 }
3948 /* Handle overload resolution for initializing an object of class type from
3949 an initializer list. First we look for a suitable constructor that
3950 takes a std::initializer_list; if we don't find one, we then look for a
3951 non-list constructor.
3953 Parameters are as for add_candidates, except that the arguments are in
3954 the form of a CONSTRUCTOR (the initializer list) rather than a vector, and
3955 the RETURN_TYPE parameter is replaced by TOTYPE, the desired type. */
3957 static void
3964 tsubst_flags_t complain)
3965 {
3968 /* We're looking for a ctor for list-initialization. */
3970 /* And we don't allow narrowing conversions. We also use this flag to
3971 avoid the copy constructor call for copy-list-initialization. */
3977 /* Always use the default constructor if the list is empty (DR 990). */
3980 ;
3981 /* If the class has a list ctor, try passing the list as a single
3982 argument first, but only consider list ctors. */
3984 {
3991 }
3994 {
3999 }
4001 /* Expand the CONSTRUCTOR into a new argument vec. */
4009 /* We aren't looking for list-ctors anymore. */
4011 /* We allow more user-defined conversions within an init-list. */
4017 }
4019 /* Returns the best overload candidate to perform the requested
4020 conversion. This function is used for three the overloading situations
4021 described in [over.match.copy], [over.match.conv], and [over.match.ref].
4022 If TOTYPE is a REFERENCE_TYPE, we're trying to find a direct binding as
4023 per [dcl.init.ref], so we ignore temporary bindings. */
4027 tsubst_flags_t complain)
4028 {
4030 tree fromtype;
4044 /* We represent conversion within a hierarchy using RVALUE_CONV and
4045 BASE_CONV, as specified by [over.best.ics]; these become plain
4046 constructor calls, as specified in [dcl.init]. */
4051 /* Use lookup_fnfields_slot instead of lookup_fnfields to avoid
4052 creating a garbage BASELINK; constructors can't be inherited. */
4057 {
4061 {
4062 /* [class.conv.fct] A conversion function is never used to
4063 convert a (possibly cv-qualified) object to the (possibly
4064 cv-qualified) same object type (or a reference to it), to a
4065 (possibly cv-qualified) base class of that type (or a
4066 reference to it)... */
4067 }
4068 else
4070 }
4077 /* It's OK to bind a temporary for converting constructor arguments, but
4078 not in converting the return value of a conversion operator. */
4084 {
4089 /* We should never try to call the abstract or base constructor
4090 from here. */
4096 {
4097 /* List-initialization. */
4101 }
4102 else
4103 {
4107 }
4110 {
4113 /* If totype isn't a reference, and LOOKUP_ONLYCONVERTING is
4114 set, then this is copy-initialization. In that case, "The
4115 result of the call is then used to direct-initialize the
4116 object that is the destination of the copy-initialization."
4117 [dcl.init]
4119 We represent this in the conversion sequence with an
4120 rvalue conversion, which means a constructor call. */
4125 cand->second_conv
4127 }
4128 }
4131 {
4134 else
4136 }
4139 {
4143 /* If LOOKUP_NO_CONVERSION, don't consider a conversion function that
4144 would need an addional user-defined conversion, i.e. if the return
4145 type differs in class-ness from the desired type. So we avoid
4146 considering operator bool when calling a copy constructor.
4148 This optimization avoids the failure in PR97600, and is allowed by
4149 [temp.inst]/9: "If the function selected by overload resolution can be
4150 determined without instantiating a class template definition, it is
4151 unspecified whether that instantiation actually takes place." */
4159 /* If we are called to convert to a reference type, we are trying to
4160 find a direct binding, so don't even consider temporaries. If
4161 we don't find a direct binding, the caller will try again to
4162 look for a temporary binding. */
4173 {
4175 /* Already rejected, don't change to -1. */
4179 conversion *ics
4181 rettype,
4184 complain);
4186 /* If LOOKUP_NO_TEMP_BIND isn't set, then this is
4187 copy-initialization. In that case, "The result of the
4188 call is then used to direct-initialize the object that is
4189 the destination of the copy-initialization." [dcl.init]
4191 We represent this in the conversion sequence with an
4192 rvalue conversion, which means a constructor call. But
4193 don't add a second rvalue conversion if there's already
4194 one there. Which there really shouldn't be, but it's
4195 harmless since we'd add it here anyway. */
4203 {
4208 }
4210 /* Limit this to non-templates for now (PR90546). */
4213 {
4214 /* If we are called to convert to a reference type, we are trying
4215 to find a direct binding per [over.match.ref], so rvaluedness
4216 must match for non-functions. */
4218 }
4221 {
4222 /* 13.3.1.5: For direct-initialization, those explicit
4223 conversion functions that are not hidden within S and
4224 yield type T or a type that can be converted to type T
4225 with a qualification conversion (4.4) are also candidate
4226 functions. */
4227 /* 13.3.1.6 doesn't have a parallel restriction, but it should;
4228 I've raised this issue with the committee. --jason 9/2011 */
4231 }
4233 {
4235 cand->reason
4239 }
4242 {
4243 /* 13.3.3.1.2: If the user-defined conversion is specified by
4244 a specialization of a conversion function template, the
4245 second standard conversion sequence shall have exact match
4246 rank. */
4249 }
4250 }
4251 }
4255 {
4259 }
4263 {
4265 {
4266 auto_diagnostic_group d;
4271 }
4280 /* If there are viable candidates, don't set ICS_BAD_FLAG; an
4281 ambiguous conversion is no worse than another user-defined
4282 conversion. */
4285 }
4287 tree convtype;
4291 /* DR 5: [in the first step of copy-initialization]...if the function
4292 is a constructor, the call initializes a temporary of the
4293 cv-unqualified version of the destination type. */
4295 else
4297 /* Build the user conversion sequence. */
4298 conv = build_conv
4300 convtype,
4306 /* We're performing the maybe-rvalue overload resolution and
4307 a conversion function is in play. Reject converting the return
4308 value of the conversion function to a base class. */
4314 /* Remember that this was a list-initialization. */
4318 /* Combine it with the second conversion sequence. */
4323 }
4325 /* Wrapper for above. */
4327 tree
4329 tsubst_flags_t complain)
4330 {
4332 tree ret;
4338 {
4341 else
4342 {
4345 }
4346 }
4347 else
4352 }
4354 /* Give a helpful diagnostic when implicit_conversion fails. */
4356 static void
4358 {
4361 /* If expr has unknown type, then it is an overloaded function.
4362 Call instantiate_type to get good error messages. */
4372 else
4373 {
4378 }
4379 }
4381 /* Worker for build_converted_constant_expr. */
4383 static tree
4386 {
4389 tree t;
4395 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4401 /* A converted constant expression of type T is an expression, implicitly
4402 converted to type T, where the converted expression is a constant
4403 expression and the implicit conversion sequence contains only
4405 * user-defined conversions,
4406 * lvalue-to-rvalue conversions (7.1),
4407 * array-to-pointer conversions (7.2),
4408 * function-to-pointer conversions (7.3),
4409 * qualification conversions (7.5),
4410 * integral promotions (7.6),
4411 * integral conversions (7.8) other than narrowing conversions (11.6.4),
4412 * null pointer conversions (7.11) from std::nullptr_t,
4413 * null member pointer conversions (7.12) from std::nullptr_t, and
4414 * function pointer conversions (7.13),
4416 and where the reference binding (if any) binds directly. */
4421 {
4423 {
4424 /* A conversion function is OK. If it isn't constexpr, we'll
4425 complain later that the argument isn't constant. */
4427 /* List-initialization is OK. */
4429 /* The lvalue-to-rvalue conversion is OK. */
4431 /* Array-to-pointer and function-to-pointer. */
4433 /* Function pointer conversions. */
4435 /* Qualification conversions. */
4441 {
4447 }
4457 /* Integral promotion or conversion. */
4460 /* Conversion from nullptr to pointer or pointer-to-member. */
4466 /* fall through. */
4471 }
4472 }
4474 /* Avoid confusing convert_nontype_argument by introducing
4475 a redundant conversion to the same reference type. */
4478 {
4482 }
4485 {
4486 /* Don't copy a class in a template. */
4491 /* Issuing conversion warnings for value-dependent expressions is
4492 likely too noisy. */
4497 }
4498 else
4499 {
4503 }
4505 /* Free all the conversions we allocated. */
4509 }
4511 /* Subroutine of convert_nontype_argument.
4513 EXPR is an expression used in a context that requires a converted
4514 constant-expression, such as a template non-type parameter. Do any
4515 necessary conversions (that are permitted for converted
4516 constant-expressions) to convert it to the desired type.
4518 This function doesn't consider explicit conversion functions. If
4519 you mean to use "a contextually converted constant expression of type
4520 bool", use build_converted_constant_bool_expr.
4522 If conversion is successful, returns the converted expression;
4523 otherwise, returns error_mark_node. */
4525 tree
4527 {
4529 complain);
4530 }
4532 /* Used to create "a contextually converted constant expression of type
4533 bool". This differs from build_converted_constant_expr in that it
4534 also considers explicit conversion functions. */
4536 tree
4538 {
4541 }
4543 /* Do any initial processing on the arguments to a function call. */
4547 {
4549 tree arg;
4552 {
4556 {
4561 }
4564 }
4566 }
4568 /* Perform overload resolution on FN, which is called with the ARGS.
4570 Return the candidate function selected by overload resolution, or
4571 NULL if the event that overload resolution failed. In the case
4572 that overload resolution fails, *CANDIDATES will be the set of
4573 candidates considered, and ANY_VIABLE_P will be set to true or
4574 false to indicate whether or not any of the candidates were
4575 viable.
4577 The ARGS should already have gone through RESOLVE_ARGS before this
4578 function is called. */
4585 {
4587 tree explicit_targs;
4598 /* Check FN. */
4602 {
4606 }
4608 /* Add the various candidate functions. */
4613 LOOKUP_NORMAL,
4619 else
4624 }
4626 /* Print an error message about being unable to build a call to FN with
4627 ARGS. ANY_VIABLE_P indicates whether any candidate functions could
4628 be located; CANDIDATES is a possibly empty list of such
4629 functions. */
4631 static void
4634 {
4637 {
4640 }
4646 auto_diagnostic_group d;
4650 else
4655 }
4657 /* Perform overload resolution on the set of deduction guides DGUIDES
4658 using ARGS. Returns the selected deduction guide, or error_mark_node
4659 if overload resolution fails. */
4661 tree
4663 tsubst_flags_t complain)
4664 {
4667 tree result;
4671 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4677 {
4681 }
4682 else
4685 /* Free all the conversions we allocated. */
4689 }
4691 /* Return an expression for a call to FN (a namespace-scope function,
4692 or a static member function) with the ARGS. This may change
4693 ARGS. */
4695 tree
4697 tsubst_flags_t complain)
4698 {
4702 tree result;
4705 {
4709 }
4714 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4718 complain);
4721 {
4723 {
4724 // If there is a single (non-viable) function candidate,
4725 // let the error be diagnosed by cp_build_function_call_vec.
4730 // Otherwise, emit notes for non-viable candidates.
4732 }
4734 }
4735 else
4736 {
4738 }
4741 && result
4747 /* Free all the conversions we allocated. */
4751 }
4753 /* Build a call to a global operator new. FNNAME is the name of the
4754 operator (either "operator new" or "operator new[]") and ARGS are
4755 the arguments provided. This may change ARGS. *SIZE points to the
4756 total number of bytes required by the allocation, and is updated if
4757 that is changed here. *COOKIE_SIZE is non-NULL if a cookie should
4758 be used. If this function determines that no cookie should be
4759 used, after all, *COOKIE_SIZE is set to NULL_TREE. If SIZE_CHECK
4760 is not NULL_TREE, it is evaluated before calculating the final
4761 array size, and if it fails, the array size is replaced with
4762 (size_t)-1 (usually triggering a std::bad_alloc exception). If FN
4763 is non-NULL, it will be set, upon return, to the allocation
4764 function called. */
4766 tree
4771 {
4773 tree fns;
4780 /* Set to (size_t)-1 if the size check fails. */
4782 {
4788 }
4794 /* Based on:
4796 [expr.new]
4798 If this lookup fails to find the name, or if the allocated type
4799 is not a class type, the allocation function's name is looked
4800 up in the global scope.
4802 we disregard block-scope declarations of "operator new". */
4807 {
4814 /* If no aligned allocation function matches, try again without the
4815 alignment. */
4816 }
4818 /* Figure out what function is being called. */
4821 complain);
4823 /* If no suitable function could be found, issue an error message
4824 and give up. */
4826 {
4830 }
4832 /* If a cookie is required, add some extra space. Whether
4833 or not a cookie is required cannot be determined until
4834 after we know which function was called. */
4836 {
4838 tree arg_types;
4841 /* Skip the size_t parameter. */
4843 /* Check the remaining parameters (if any). */
4847 ptr_type_node))
4849 /* If we need a cookie, adjust the number of bytes allocated. */
4851 {
4852 /* Update the total size. */
4855 {
4856 /* Set to (size_t)-1 if the size check fails. */
4860 }
4861 /* Update the argument list to reflect the adjusted size. */
4863 }
4864 else
4866 }
4868 /* Tell our caller which function we decided to call. */
4872 /* Build the CALL_EXPR. */
4875 /* Set this flag for all callers of this function. In addition to
4876 new-expressions, this is called for allocating coroutine state; treat
4877 that as an implicit new-expression. */
4883 }
4885 /* Build a new call to operator(). This may change ARGS. */
4887 static tree
4889 {
4906 {
4908 /* It's no good looking for an overloaded operator() on a
4909 pointer-to-member-function. */
4913 }
4916 {
4920 }
4921 else
4925 {
4929 }
4931 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4935 {
4943 }
4948 {
4956 {
4961 add_template_conv_candidate
4965 else
4969 }
4970 }
4972 /* Be strict here because if we choose a bad conversion candidate, the
4973 errors we get won't mention the call context. */
4976 {
4978 {
4979 auto_diagnostic_group d;
4983 }
4985 }
4986 else
4987 {
4990 {
4992 {
4993 auto_diagnostic_group d;
4997 }
4999 }
5004 else
5005 {
5009 else
5010 {
5013 }
5016 }
5017 }
5019 /* Free all the conversions we allocated. */
5023 }
5025 /* Wrapper for above. */
5027 tree
5029 {
5030 tree ret;
5035 }
5037 /* Called by op_error to prepare format strings suitable for the error
5038 function. It concatenates a prefix (controlled by MATCH), ERRMSG,
5039 and a suffix (controlled by NTYPES). */
5043 {
5053 else
5057 }
5059 static void
5063 {
5068 {
5074 else
5086 else
5096 else
5107 else
5116 else
5125 {
5130 }
5131 else
5136 else
5140 else
5145 }
5146 }
5148 /* Return the implicit conversion sequence that could be used to
5149 convert E1 to E2 in [expr.cond]. */
5153 {
5159 /* [expr.cond]
5161 If E2 is an lvalue: E1 can be converted to match E2 if E1 can be
5162 implicitly converted (clause _conv_) to the type "lvalue reference to
5163 T2", subject to the constraint that in the conversion the
5164 reference must bind directly (_dcl.init.ref_) to an lvalue.
5166 If E2 is an xvalue: E1 can be converted to match E2 if E1 can be
5167 implicitly converted to the type "rvalue reference to T2", subject to
5168 the constraint that the reference must bind directly. */
5170 {
5173 t1,
5174 e1,
5176 LOOKUP_NO_TEMP_BIND|LOOKUP_NO_RVAL_BIND
5178 complain);
5181 }
5183 /* If E2 is a prvalue or if neither of the conversions above can be done
5184 and at least one of the operands has (possibly cv-qualified) class
5185 type: */
5189 /* [expr.cond]
5191 If E1 and E2 have class type, and the underlying class types are
5192 the same or one is a base class of the other: E1 can be converted
5193 to match E2 if the class of T2 is the same type as, or a base
5194 class of, the class of T1, and the cv-qualification of T2 is the
5195 same cv-qualification as, or a greater cv-qualification than, the
5196 cv-qualification of T1. If the conversion is applied, E1 is
5197 changed to an rvalue of type T2 that still refers to the original
5198 source class object (or the appropriate subobject thereof). */
5201 {
5203 {
5208 else
5211 }
5212 else
5214 }
5215 else
5216 /* [expr.cond]
5218 Otherwise: E1 can be converted to match E2 if E1 can be implicitly
5219 converted to the type that expression E2 would have if E2 were
5220 converted to an rvalue (or the type it has, if E2 is an rvalue). */
5223 }
5225 /* Implement [expr.cond]. ARG1, ARG2, and ARG3 are the three
5226 arguments to the conditional expression. */
5228 static tree
5231 tsubst_flags_t complain)
5232 {
5233 tree arg2_type;
5234 tree arg3_type;
5243 /* As a G++ extension, the second argument to the conditional can be
5244 omitted. (So that `a ? : c' is roughly equivalent to `a ? a :
5245 c'.) If the second operand is omitted, make sure it is
5246 calculated only once. */
5248 {
5251 "ISO C++ forbids omitting the middle term of "
5257 /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */
5259 {
5262 }
5263 else
5265 }
5267 /* If something has already gone wrong, just pass that fact up the
5268 tree. */
5279 {
5282 /* If arg1 is another cond_expr choosing between -1 and 0,
5283 then we can use its comparison. It may help to avoid
5284 additional comparison, produce more accurate diagnostics
5285 and enables folding. */
5295 /* force_rvalue can return error_mark on valid arguments. */
5306 {
5307 /* Rely on the error messages of the scalar version. */
5316 {
5324 }
5328 /* We could pass complain & tf_warning to unsafe_conversion_p,
5329 but the warnings (like Wsign-conversion) have already been
5330 given by the scalar build_conditional_expr_1. We still check
5331 unsafe_conversion_p to forbid truncating long long -> float. */
5333 {
5338 }
5340 {
5345 }
5355 }
5359 {
5365 {
5369 {
5375 }
5377 {
5383 }
5386 }
5387 }
5395 {
5398 "incompatible vector types in conditional expression: "
5402 }
5405 {
5408 }
5410 }
5412 /* [expr.cond]
5414 The first expression is implicitly converted to bool (clause
5415 _conv_). */
5417 LOOKUP_NORMAL);
5421 /* [expr.cond]
5423 If either the second or the third operand has type (possibly
5424 cv-qualified) void, then the lvalue-to-rvalue (_conv.lval_),
5425 array-to-pointer (_conv.array_), and function-to-pointer
5426 (_conv.func_) standard conversions are performed on the second
5427 and third operands. */
5431 {
5432 /* 'void' won't help in resolving an overloaded expression on the
5433 other side, so require it to resolve by itself. */
5435 {
5438 }
5440 {
5443 }
5445 /* [expr.cond]
5447 One of the following shall hold:
5449 --The second or the third operand (but not both) is a
5450 throw-expression (_except.throw_); the result is of the type
5451 and value category of the other.
5453 --Both the second and the third operands have type void; the
5454 result is of type void and is a prvalue. */
5457 {
5460 }
5463 {
5466 }
5468 {
5471 }
5472 else
5473 {
5475 {
5478 "second operand to the conditional operator "
5479 "is of type %<void%>, but the third operand is "
5481 else
5483 "third operand to the conditional operator "
5484 "is of type %<void%>, but the second operand is "
5486 }
5488 }
5491 }
5492 /* [expr.cond]
5494 Otherwise, if the second and third operand have different types,
5495 and either has (possibly cv-qualified) class type, or if both are
5496 glvalues of the same value category and the same type except for
5497 cv-qualification, an attempt is made to convert each of those operands
5498 to the type of the other. */
5502 arg3_type)
5505 {
5510 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5516 /* [expr.cond]
5518 If both can be converted, or one can be converted but the
5519 conversion is ambiguous, the program is ill-formed. If
5520 neither can be converted, the operands are left unchanged and
5521 further checking is performed as described below. If exactly
5522 one conversion is possible, that conversion is applied to the
5523 chosen operand and the converted operand is used in place of
5524 the original operand for the remainder of this section. */
5529 {
5531 {
5539 else
5541 }
5543 }
5545 {
5549 /* Even if CONV2 is a valid conversion, the result of the
5550 conversion may be invalid. For example, if ARG3 has type
5551 "volatile X", and X does not have a copy constructor
5552 accepting a "volatile X&", then even if ARG2 can be
5553 converted to X, the conversion will fail. */
5557 }
5559 {
5566 }
5568 /* Free all the conversions we allocated. */
5574 /* If, after the conversion, both operands have class type,
5575 treat the cv-qualification of both operands as if it were the
5576 union of the cv-qualification of the operands.
5578 The standard is not clear about what to do in this
5579 circumstance. For example, if the first operand has type
5580 "const X" and the second operand has a user-defined
5581 conversion to "volatile X", what is the type of the second
5582 operand after this step? Making it be "const X" (matching
5583 the first operand) seems wrong, as that discards the
5584 qualification without actually performing a copy. Leaving it
5585 as "volatile X" seems wrong as that will result in the
5586 conditional expression failing altogether, even though,
5587 according to this step, the one operand could be converted to
5588 the type of the other. */
5596 }
5598 /* [expr.cond]
5600 If the second and third operands are glvalues of the same value
5601 category and have the same type, the result is of that type and
5602 value category. */
5606 {
5609 }
5611 /* [expr.cond]
5613 Otherwise, the result is an rvalue. If the second and third
5614 operand do not have the same type, and either has (possibly
5615 cv-qualified) class type, overload resolution is used to
5616 determine the conversions (if any) to be applied to the operands
5617 (_over.match.oper_, _over.built_). */
5621 {
5622 releasing_vec args;
5626 /* Rearrange the arguments so that add_builtin_candidate only has
5627 to know about two args. In build_builtin_candidate, the
5628 arguments are unscrambled. */
5633 COND_EXPR,
5634 NOP_EXPR,
5636 args,
5639 /* [expr.cond]
5641 If the overload resolution fails, the program is
5642 ill-formed. */
5645 {
5650 }
5653 {
5655 {
5656 auto_diagnostic_group d;
5659 }
5661 }
5663 /* [expr.cond]
5665 Otherwise, the conversions thus determined are applied, and
5666 the converted operands are used in place of the original
5667 operands for the remainder of this section. */
5676 }
5678 /* [expr.cond]
5680 Lvalue-to-rvalue (_conv.lval_), array-to-pointer (_conv.array_),
5681 and function-to-pointer (_conv.func_) standard conversions are
5682 performed on the second and third operands.
5684 We need to force the lvalue-to-rvalue conversion here for class types,
5685 so we get TARGET_EXPRs; trying to deal with a COND_EXPR of class rvalues
5686 that isn't wrapped with a TARGET_EXPR plays havoc with exception
5687 regions. */
5700 /* [expr.cond]
5702 After those conversions, one of the following shall hold:
5704 --The second and third operands have the same type; the result is of
5705 that type. */
5708 /* [expr.cond]
5710 --The second and third operands have arithmetic or enumeration
5711 type; the usual arithmetic conversions are performed to bring
5712 them to a common type, and the result is of that type. */
5717 {
5718 /* In this case, there is always a common type. */
5720 arg3_type);
5723 "implicit conversion from %qH to %qI to "
5725 loc);
5729 {
5736 /* Two enumerators from the same enumeration can have different
5742 }
5744 && warn_deprecated_enum_float_conv
5749 {
5752 "conditional expression between enumeration type "
5755 else
5757 "conditional expression between floating-point "
5760 }
5767 {
5769 {
5771 ? OPT_Wenum_conversion
5775 }
5776 }
5780 }
5781 /* [expr.cond]
5783 --The second and third operands have pointer type, or one has
5784 pointer type and the other is a null pointer constant; pointer
5785 conversions (_conv.ptr_) and qualification conversions
5786 (_conv.qual_) are performed to bring them to their composite
5787 pointer type (_expr.rel_). The result is of the composite
5788 pointer type.
5790 --The second and third operands have pointer to member type, or
5791 one has pointer to member type and the other is a null pointer
5792 constant; pointer to member conversions (_conv.mem_) and
5793 qualification conversions (_conv.qual_) are performed to bring
5794 them to a common type, whose cv-qualification shall match the
5795 cv-qualification of either the second or the third operand.
5796 The result is of the common type. */
5804 {
5808 complain);
5813 }
5816 {
5821 }
5826 valid_operands:
5828 {
5829 /* Let lvalue_kind know this was a glvalue. */
5832 }
5836 /* If the ARG2 and ARG3 are the same and don't have side-effects,
5837 warn here, because the COND_EXPR will be turned into ARG2. */
5841 OEP_ADDRESS_OF_SAME_FIELD)))
5845 /* We can't use result_type below, as fold might have returned a
5846 throw_expr. */
5849 {
5850 /* Expand both sides into the same slot, hopefully the target of
5851 the ?: expression. We used to check for TARGET_EXPRs here,
5852 but now we sometimes wrap them in NOP_EXPRs so the test would
5853 fail. */
5856 /* If this expression is an rvalue, but might be mistaken for an
5857 lvalue, we must add a NON_LVALUE_EXPR. */
5859 }
5860 else
5864 }
5866 /* Wrapper for above. */
5868 tree
5871 tsubst_flags_t complain)
5872 {
5873 tree ret;
5878 }
5880 /* OPERAND is an operand to an expression. Perform necessary steps
5881 required before using it. If OPERAND is NULL_TREE, NULL_TREE is
5882 returned. */
5884 static tree
5886 {
5888 {
5891 /* Make sure the template type is instantiated now. */
5893 }
5896 }
5898 /* True iff CONV represents a conversion sequence which no other can be better
5899 than under [over.ics.rank]: in other words, a "conversion" to the exact same
5900 type (including binding to a reference to the same type). This is stronger
5901 than the standard's "identity" category, which also includes reference
5902 bindings that add cv-qualifiers or change rvalueness. */
5904 static bool
5906 {
5910 {
5916 }
5918 /* Brace elision is imperfect. */
5921 }
5923 /* True if CAND represents a perfect match, i.e. all perfect conversions, so no
5924 other candidate can be a better match. Since the template/non-template
5925 tiebreaker comes immediately after the conversion comparison in
5926 [over.match.best], a perfect non-template candidate is better than all
5927 templates. */
5929 static bool
5931 {
5934 /* CWG1402 makes an implicitly deleted move op worse than other
5935 candidates. */
5947 }
5949 /* Add each of the viable functions in FNS (a FUNCTION_DECL or
5950 OVERLOAD) to the CANDIDATES, returning an updated list of
5951 CANDIDATES. The ARGS are the arguments provided to the call;
5952 if FIRST_ARG is non-null it is the implicit object argument,
5953 otherwise the first element of ARGS is used if needed. The
5954 EXPLICIT_TARGS are explicit template arguments provided.
5955 TEMPLATE_ONLY is true if only template functions should be
5956 considered. CONVERSION_PATH, ACCESS_PATH, and FLAGS are as for
5957 add_function_candidate. */
5959 static void
5961 tree return_type,
5966 tsubst_flags_t complain)
5967 {
5968 tree ctype;
5972 unification_kind_t strict;
5977 /* Precalculate special handling of constructors and conversion ops. */
5980 {
5984 /* We're doing return_type(x). */
5986 else
5987 /* We're doing x.operator return_type(). */
5989 /* [over.match.funcs] For conversion functions, the function
5990 is considered to be a member of the class of the implicit
5991 object argument for the purpose of defining the type of
5992 the implicit object parameter. */
5994 }
5995 else
5996 {
5998 {
6000 /* For list-initialization we consider explicit constructors
6001 and complain if one is chosen. */
6002 check_converting
6005 }
6008 }
6012 else
6013 /* Delay creating the implicit this parameter until it is needed. */
6016 /* If there's a non-template perfect match, we don't need to consider
6017 templates. So check non-templates first. This optimization is only
6018 really needed for the defaulted copy constructor of tuple and the like
6019 (96926), but it seems like we might as well enable it more generally. */
6027 again:
6029 {
6043 {
6044 /* Figure out where the object arg comes from. If this
6045 function is a non-static member and we didn't get an
6046 implicit object argument, move it out of args. */
6048 {
6050 tree arg;
6057 }
6061 }
6063 /* Don't bother reversing an operator with two identical parameters. */
6065 {
6070 }
6074 fn,
6075 ctype,
6076 explicit_targs,
6077 fn_first_arg,
6078 fn_args,
6079 return_type,
6080 access_path,
6081 conversion_path,
6082 flags,
6083 strict,
6084 complain);
6085 else
6086 {
6088 fn,
6089 ctype,
6090 fn_first_arg,
6091 fn_args,
6092 access_path,
6093 conversion_path,
6094 flags,
6095 NULL,
6096 complain);
6099 }
6100 }
6102 {
6105 }
6106 }
6108 /* Returns 1 if P0145R2 says that the LHS of operator CODE is evaluated first,
6109 -1 if the RHS is evaluated first, or 0 if the order is unspecified. */
6111 static int
6113 {
6115 {
6116 // 5. b @= a
6120 // 6. a[b]
6124 // 1. a.b
6125 // Not overloadable (yet).
6126 // 2. a->b
6127 // Only one argument.
6128 // 3. a->*b
6130 // 7. a << b
6132 // 8. a >> b
6134 // a && b
6135 // Predates P0145R3.
6137 // a || b
6138 // Predates P0145R3.
6140 // a , b
6141 // Predates P0145R3.
6147 }
6148 }
6150 /* Subroutine of build_new_op_1: Add to CANDIDATES all candidates for the
6151 operator indicated by CODE/CODE2. This function calls itself recursively to
6152 handle C++20 rewritten comparison operator candidates. */
6154 static tree
6159 {
6164 /* LOOKUP_REWRITTEN is set when we're looking for the == or <=> operator to
6165 rewrite from, and also when we're looking for the e.g. < operator to use
6166 on the result of <=>. In the latter case, we don't want the flag set in
6167 the candidate, we just want to suppress looking for rewrites. */
6174 {
6175 /* =, ->, [], () must be non-static member functions. */
6179 /* FALLTHRU */
6187 }
6189 /* Add namespace-scope operators to the list of functions to
6190 consider. */
6192 {
6198 }
6200 /* Add class-member operators to the candidate set. */
6205 {
6216 }
6217 /* Per [over.match.oper]3.2, if no operand has a class type, then
6218 only non-member functions that have type T1 or reference to
6219 cv-qualified-opt T1 for the first argument, if the first argument
6220 has an enumeration type, or T2 or reference to cv-qualified-opt
6221 T2 for the second argument, if the second argument has an
6222 enumeration type. Filter out those that don't match. */
6224 {
6228 {
6236 {
6243 && (same_type_ignoring_top_level_qualifiers_p
6248 }
6250 /* No argument has an appropriate type, so remove this
6251 candidate function from the list. */
6253 {
6256 }
6257 }
6258 }
6261 {
6262 /* The standard says to rewrite built-in candidates, too,
6263 but there's no point. */
6267 /* Maybe add C++20 rewritten comparison candidates. */
6273 {
6288 }
6291 {
6294 /* Add rewritten candidates in same order. */
6300 /* Add rewritten candidates in reverse order. */
6308 /* Release the vec if we didn't add a candidate that uses it. */
6311 {
6314 }
6316 }
6317 }
6320 }
6322 static tree
6325 tsubst_flags_t complain)
6326 {
6346 {
6349 }
6357 {
6362 /* Use build_operator_new_call and build_op_delete_call instead. */
6366 /* Use build_op_call instead. */
6373 /* These are saved for the sake of warn_logical_operator. */
6383 /* These are saved for the sake of maybe_warn_bool_compare. */
6390 }
6396 /* Use build_conditional_expr instead. */
6403 {
6406 }
6415 /* Get the high-water mark for the CONVERSION_OBSTACK. */
6424 {
6427 /* For these, the built-in candidates set is empty
6428 [over.match.oper]/3. We don't want non-strict matches
6429 because exact matches are always possible with built-in
6430 operators. The built-in candidate set for COMPONENT_REF
6431 would be empty too, but since there are no such built-in
6432 operators, we accept non-strict matches for them. */
6439 }
6443 {
6445 {
6448 /* Don't try anything fancy if we're not allowed to produce
6449 errors. */
6453 /* Look for an `operator++ (int)'. Pre-1985 C++ didn't
6454 distinguish between prefix and postfix ++ and
6455 operator++() was used for both, so we allow this with
6456 -fpermissive. */
6457 else
6458 {
6465 }
6472 else
6478 /* The caller will deal with these. */
6489 {
6490 /* If one of the arguments of the operator represents
6491 an invalid use of member function pointer, try to report
6492 a meaningful error ... */
6497 else
6498 {
6499 /* ... Otherwise, report the more generic
6500 "no matching operator found" error */
6501 auto_diagnostic_group d;
6504 }
6505 }
6508 }
6509 }
6510 else
6511 {
6514 {
6516 {
6517 auto_diagnostic_group d;
6520 }
6524 }
6526 {
6532 else
6533 {
6536 /* We'll wrap this call in another one. */
6539 {
6540 /* We swapped these in add_candidate, swap them back now. */
6544 "current function recursively with reversed "
6546 }
6548 }
6553 {
6557 /* Specify evaluation order as per P0145R2. */
6560 {
6571 }
6572 }
6574 /* If this was a C++20 rewritten comparison, adjust the result. */
6576 {
6577 /* FIXME build_min_non_dep_op_overload can't handle rewrites. */
6581 {
6586 /* If a rewritten operator== candidate is selected by
6587 overload resolution for an operator @, its return type
6588 shall be cv bool.... */
6590 {
6592 {
6593 auto_diagnostic_group d;
6599 }
6601 }
6603 /* !(y == x) or !(x == y) */
6608 /* If a rewritten operator<=> candidate is selected by
6609 overload resolution for an operator @, x @ y is
6610 interpreted as 0 @ (y <=> x) if the selected candidate is
6611 a synthesized candidate with reversed order of parameters,
6612 or (x <=> y) @ 0 otherwise, using the selected rewritten
6613 operator<=> candidate. */
6616 /* We're in the build_new_op call below for an outer
6617 reversed call; we don't need to do anything more. */
6624 {
6634 }
6639 }
6640 }
6641 }
6642 else
6643 {
6644 /* Give any warnings we noticed during overload resolution. */
6646 {
6650 }
6652 /* Check for comparison of different enum types. */
6654 {
6672 }
6674 /* "If a built-in candidate is selected by overload resolution, the
6675 operands of class type are converted to the types of the
6676 corresponding parameters of the selected operation function,
6677 except that the second standard conversion sequence of a
6678 user-defined conversion sequence (12.3.3.1.2) is not applied." */
6681 {
6684 }
6687 {
6690 {
6693 }
6694 }
6697 {
6700 {
6703 }
6704 }
6705 }
6706 }
6708 user_defined_result_ready:
6710 /* Free all the conversions we allocated. */
6716 builtin:
6718 {
6733 /* Fall through. */
6746 /* Fall through. */
6781 RO_ARROW_STAR,
6782 complain),
6785 /* The caller will deal with these. */
6793 }
6795 }
6797 /* Wrapper for above. */
6799 tree
6803 {
6804 tree ret;
6810 }
6812 /* CALL was returned by some call-building function; extract the actual
6813 CALL_EXPR from any bits that have been tacked on, e.g. by
6814 convert_from_reference. */
6816 tree
6818 {
6827 {
6828 /* C++20 rewritten comparison operators. */
6837 {
6841 else
6843 }
6846 }
6852 }
6854 /* Returns true if FN has two parameters, of which the second has type
6855 size_t. */
6857 static bool
6859 {
6867 }
6869 /* True if T, an allocation function, has std::align_val_t as its second
6870 argument. */
6872 bool
6874 {
6880 }
6882 /* True if T is std::destroying_delete_t. */
6884 static bool
6886 {
6889 }
6891 /* A deallocation function with at least two parameters whose second parameter
6892 type is of type std::destroying_delete_t is a destroying operator delete. A
6893 destroying operator delete shall be a class member function named operator
6894 delete. [ Note: Array deletion cannot use a destroying operator
6895 delete. --end note ] */
6897 tree
6899 {
6905 }
6907 struct dealloc_info
6908 {
6911 tree destroying;
6912 };
6914 /* Returns true iff T, an element of an OVERLOAD chain, is a usual deallocation
6915 function (3.7.4.2 [basic.stc.dynamic.deallocation]). If so, and DI is
6916 non-null, also set *DI. */
6918 static bool
6920 {
6923 /* A template instance is never a usual deallocation function,
6924 regardless of its signature. */
6929 /* A usual deallocation function is a deallocation function whose parameters
6930 after the first are
6931 - optionally, a parameter of type std::destroying_delete_t, then
6932 - optionally, a parameter of type std::size_t, then
6933 - optionally, a parameter of type std::align_val_t. */
6937 {
6940 }
6944 {
6947 }
6950 {
6953 }
6955 }
6957 /* Just return whether FN is a usual deallocation function. */
6959 bool
6961 {
6963 }
6965 /* Build a call to operator delete. This has to be handled very specially,
6966 because the restrictions on what signatures match are different from all
6967 other call instances. For a normal delete, only a delete taking (void *)
6968 or (void *, size_t) is accepted. For a placement delete, only an exact
6969 match with the placement new is accepted.
6971 CODE is either DELETE_EXPR or VEC_DELETE_EXPR.
6972 ADDR is the pointer to be deleted.
6973 SIZE is the size of the memory block to be deleted.
6974 GLOBAL_P is true if the delete-expression should not consider
6975 class-specific delete operators.
6976 PLACEMENT is the corresponding placement new call, or NULL_TREE.
6978 If this call to "operator delete" is being generated as part to
6979 deallocate memory allocated via a new-expression (as per [expr.new]
6980 which requires that if the initialization throws an exception then
6981 we call a deallocation function), then ALLOC_FN is the allocation
6982 function. */
6984 tree
6988 {
6991 dealloc_info di_fn = { };
7003 /* In [class.free]
7005 If the result of the lookup is ambiguous or inaccessible, or if
7006 the lookup selects a placement deallocation function, the
7007 program is ill-formed.
7009 Therefore, we ask lookup_fnfields to complain about ambiguity. */
7010 {
7014 }
7015 else
7021 /* Strip const and volatile from addr. */
7026 {
7027 /* "A declaration of a placement deallocation function matches the
7028 declaration of a placement allocation function if it has the same
7029 number of parameters and, after parameter transformations (8.3.5),
7030 all parameter types except the first are identical."
7032 So we build up the function type we want and ask instantiate_type
7033 to get it for us. */
7044 /* "If the lookup finds the two-parameter form of a usual deallocation
7045 function (3.7.4.2) and that function, considered as a placement
7046 deallocation function, would have been selected as a match for the
7047 allocation function, the program is ill-formed." */
7049 {
7057 /* But if the class has an operator delete (void *), then that is
7058 the usual deallocation function, so we shouldn't complain
7059 about using the operator delete (void *, size_t). */
7062 {
7066 }
7067 /* Before C++14 a two-parameter global deallocation function is
7068 always a placement deallocation function, but warn if
7069 -Wc++14-compat. */
7071 {
7073 {
7074 auto_diagnostic_group d;
7077 }
7079 }
7082 {
7083 auto_diagnostic_group d;
7085 {
7086 /* Only mention C++14 for namespace-scope delete. */
7089 else
7091 "%qD is a usual (non-placement) deallocation "
7093 }
7094 }
7095 else
7097 ok:;
7098 }
7099 }
7100 else
7101 /* "Any non-placement deallocation function matches a non-placement
7102 allocation function. If the lookup finds a single matching
7103 deallocation function, that function will be called; otherwise, no
7104 deallocation function will be called." */
7106 {
7107 dealloc_info di_elt;
7109 {
7111 {
7115 }
7117 /* -- If any of the deallocation functions is a destroying
7118 operator delete, all deallocation functions that are not
7119 destroying operator deletes are eliminated from further
7120 consideration. */
7122 {
7124 {
7127 }
7129 }
7131 /* -- If the type has new-extended alignment, a function with a
7132 parameter of type std::align_val_t is preferred; otherwise a
7133 function without such a parameter is preferred. If exactly one
7134 preferred function is found, that function is selected and the
7135 selection process terminates. If more than one preferred
7136 function is found, all non-preferred functions are eliminated
7137 from further consideration. */
7139 {
7142 {
7144 {
7147 }
7149 }
7150 }
7152 /* -- If the deallocation functions have class scope, the one
7153 without a parameter of type std::size_t is selected. */
7158 /* -- If the type is complete and if, for the second alternative
7159 (delete array) only, the operand is a pointer to a class type
7160 with a non-trivial destructor or a (possibly multi-dimensional)
7161 array thereof, the function with a parameter of type std::size_t
7162 is selected.
7164 -- Otherwise, it is unspecified whether a deallocation function
7165 with a parameter of type std::size_t is selected. */
7166 else
7167 {
7171 /* We need a cookie to determine the array size. */
7173 }
7176 {
7179 }
7180 }
7181 }
7183 /* If we have a matching function, call it. */
7185 {
7188 /* If the FN is a member function, make sure that it is
7189 accessible. */
7192 complain);
7194 /* Core issue 901: It's ok to new a type with deleted delete. */
7198 tree ret;
7200 {
7201 /* The placement args might not be suitable for overload
7202 resolution at this point, so build the call directly. */
7212 }
7213 else
7214 {
7217 {
7218 /* Strip const and volatile from addr but retain the type of the
7219 object. */
7226 complain);
7227 }
7229 releasing_vec args;
7236 {
7239 }
7241 }
7243 /* Set this flag for all callers of this function. In addition to
7244 delete-expressions, this is called for deallocating coroutine state;
7245 treat that as an implicit delete-expression. This is also called for
7246 the delete if the constructor throws in a new-expression, and for a
7247 deleting destructor (which implements a delete-expression). */
7248 /* But leave this flag off for destroying delete to avoid wrong
7249 assumptions in the optimizers. */
7255 }
7257 /* [expr.new]
7259 If no unambiguous matching deallocation function can be found,
7260 propagating the exception does not cause the object's memory to
7261 be freed. */
7263 {
7267 alloc_fn);
7269 }
7275 }
7277 /* Issue diagnostics about a disallowed access of DECL, using DIAG_DECL
7278 in the diagnostics.
7280 If ISSUE_ERROR is true, then issue an error about the access, followed
7281 by a note showing the declaration. Otherwise, just show the note.
7283 DIAG_DECL and DIAG_LOCATION will almost always be the same.
7284 DIAG_LOCATION is just another DECL. NO_ACCESS_REASON is an optional
7285 parameter used to specify why DECL wasn't accessible (e.g. ak_private
7286 would be because DECL was private). If not using NO_ACCESS_REASON,
7287 then it must be ak_none, and the access failure reason will be
7288 figured out by looking at the protection of DECL. */
7290 void
7293 {
7294 /* If we have not already figured out why DECL is inaccessible... */
7296 {
7297 /* Examine the access of DECL to find out why. */
7302 }
7304 /* Now generate an error message depending on calculated access. */
7306 {
7310 }
7312 {
7316 }
7317 /* Couldn't figure out why DECL is inaccesible, so just say it's
7318 inaccessible. */
7319 else
7320 {
7324 }
7325 }
7327 /* Initialize a temporary of type TYPE with EXPR. The FLAGS are a
7328 bitwise or of LOOKUP_* values. If any errors are warnings are
7329 generated, set *DIAGNOSTIC_FN to "error" or "warning",
7330 respectively. If no diagnostics are generated, set *DIAGNOSTIC_FN
7331 to NULL. */
7333 static tree
7336 {
7341 /* If the source is a packed field, calling the copy constructor will require
7342 binding the field to the reference parameter to the copy constructor, and
7343 we'll end up with an infinite loop. If we can use a bitwise copy, then
7344 do that now. */
7350 /* In decltype, we might have decided not to wrap this call in a TARGET_EXPR.
7351 But it turns out to be a subexpression, so perform temporary
7352 materialization now. */
7367 }
7369 /* Get any location for EXPR, falling back to input_location.
7371 If the result is in a system header and is the virtual location for
7372 a token coming from the expansion of a macro, unwind it to the
7373 location of the expansion point of the macro (e.g. to avoid the
7374 diagnostic being suppressed for expansions of NULL where "NULL" is
7375 in a system header). */
7377 static location_t
7379 {
7383 }
7385 /* Perform warnings about peculiar, but valid, conversions from/to NULL.
7386 Also handle a subset of zero as null warnings.
7387 EXPR is implicitly converted to type TOTYPE.
7388 FN and ARGNUM are used for diagnostics. */
7390 static void
7392 {
7393 /* Issue warnings about peculiar, but valid, uses of NULL. */
7397 {
7400 {
7401 auto_diagnostic_group d;
7407 }
7408 else
7411 }
7413 /* Issue warnings if "false" is converted to a NULL pointer */
7416 {
7419 {
7420 auto_diagnostic_group d;
7422 "converting %<false%> to pointer type for argument "
7426 }
7427 else
7430 }
7431 /* Handle zero as null pointer warnings for cases other
7432 than EQ_EXPR and NE_EXPR */
7435 {
7438 }
7439 }
7441 /* We gave a diagnostic during a conversion. If this was in the second
7442 standard conversion sequence of a user-defined conversion sequence, say
7443 which user-defined conversion. */
7445 static void
7447 {
7451 {
7455 }
7456 }
7458 /* Locate the parameter with the given index within FNDECL.
7459 ARGNUM is zero based, -1 indicates the `this' argument of a method.
7460 Return the location of the FNDECL itself if there are problems. */
7462 location_t
7464 {
7465 /* The locations of implicitly-declared functions are likely to be
7466 more meaningful than those of their parameters. */
7471 tree param;
7473 /* Locate param by index within DECL_ARGUMENTS (fndecl). */
7477 ;
7479 /* If something went wrong (e.g. if we have a builtin and thus no arguments),
7480 return the location of FNDECL. */
7485 }
7487 /* If FNDECL is non-NULL, issue a note highlighting ARGNUM
7488 within its declaration (or the fndecl itself if something went
7489 wrong). */
7491 void
7493 {
7497 }
7499 /* Maybe warn about C++20 Conversions to arrays of unknown bound. C is
7500 the conversion, EXPR is the expression we're converting. */
7502 static void
7504 {
7517 "conversions to arrays of unknown bound "
7519 }
7521 /* We call this recursively in convert_like_internal. */
7523 tsubst_flags_t);
7525 /* Perform the conversions in CONVS on the expression EXPR. FN and
7526 ARGNUM are used for diagnostics. ARGNUM is zero based, -1
7527 indicates the `this' argument of a method. INNER is nonzero when
7528 being called to continue a conversion chain. It is negative when a
7529 reference binding will be applied, positive otherwise. If
7530 ISSUE_CONVERSION_WARNINGS is true, warnings about suspicious
7531 conversions will be emitted if appropriate. If C_CAST_P is true,
7532 this conversion is coming from a C-style cast; in that case,
7533 conversions to inaccessible bases are permitted. */
7535 static tree
7538 tsubst_flags_t complain)
7539 {
7541 diagnostic_t diag_kind;
7557 {
7561 /* Give a helpful error if this is bad because of excess braces. */
7566 {
7572 }
7574 /* Give a helpful error if this is bad because a conversion to bool
7575 from std::nullptr_t requires direct-initialization. */
7583 {
7585 {
7586 auto_diagnostic_group d;
7589 totype);
7598 complain);
7599 else
7604 }
7606 {
7611 }
7618 }
7620 {
7626 }
7631 }
7637 {
7639 {
7643 /* We chose the surrogate function from add_conv_candidate, now we
7644 actually need to build the conversion. */
7650 /* When converting from an init list we consider explicit
7651 constructors, but actually trying to call one is an error. */
7654 /* Unless this is for direct-list-initialization. */
7656 /* And in C++98 a default constructor can't be explicit. */
7658 {
7664 {
7665 auto_diagnostic_group d;
7671 }
7672 else
7675 }
7677 /* If we're initializing from {}, it's value-initialization. */
7682 {
7689 {
7692 }
7694 }
7696 /* We don't know here whether EXPR is being used as an lvalue or
7697 rvalue, but we know it's read. */
7700 /* Pass LOOKUP_NO_CONVERSION so rvalue/base handling knows not to allow
7701 any more UDCs. */
7703 complain);
7705 /* If this is a constructor or a function returning an aggr type,
7706 we need to build up a TARGET_EXPR. */
7708 {
7711 /* Remember that this was list-initialization. */
7714 }
7717 }
7720 {
7726 else
7728 }
7737 /* If __null has been converted to an integer type, we do not want to
7738 continue to warn about uses of EXPR as an integer, rather than as a
7739 pointer. */
7743 /* We leave bad_p off ck_ambig because overload resolution considers
7744 it valid, it just fails when we try to perform it. So we need to
7745 check complain here, too. */
7747 {
7748 /* Call build_user_type_conversion again for the error. */
7754 }
7758 {
7759 /* Conversion to std::initializer_list<T>. */
7762 tree array;
7765 {
7770 /* Convert all the elements. */
7772 {
7784 }
7785 /* Build up the array. */
7786 elttype = cp_build_qualified_type
7790 /* Take the address explicitly rather than via decay_conversion
7791 to avoid the error about taking the address of a temporary. */
7793 }
7794 else
7801 /* Build up the initializer_list object. Note: fail gracefully
7802 if the object cannot be completed because, for example, no
7803 definition is provided (c++/80956). */
7814 }
7818 {
7827 }
7830 complain);
7837 };
7847 {
7851 {
7853 {
7854 auto_diagnostic_group d;
7857 }
7859 }
7864 /* Don't introduce copies when passing arguments along to the inherited
7865 constructor. */
7867 && flag_new_inheriting_ctors
7873 /* Copy-list-initialization doesn't actually involve a copy. */
7876 /* Fall through. */
7879 {
7880 /* We are going to bind a reference directly to a base-class
7881 subobject of EXPR. */
7882 /* Build an expression for `*((base*) &expr)'. */
7886 }
7888 /* Copy-initialization where the cv-unqualified version of the source
7889 type is the same class as, or a derived class of, the class of the
7890 destination [is treated as direct-initialization]. [dcl.init] */
7892 /* This conversion is being done in the context of a user-defined
7893 conversion (i.e. the second step of copy-initialization), so
7894 don't allow any more. */
7897 /* We might be performing a conversion of the argument
7898 to the user-defined conversion, i.e., not a conversion of the
7899 result of the user-defined conversion. In which case we skip
7900 explicit constructors. */
7904 /* standard_conversion got LOOKUP_PREFER_RVALUE. */
7908 {
7909 auto_diagnostic_group d;
7912 }
7917 {
7920 /* direct_reference_binding might have inserted a ck_qual under
7921 this ck_ref_bind for the benefit of conversion sequence ranking.
7922 Ignore the conversion; we'll create our own below. */
7925 {
7928 /* Strip the cast created by the ck_qual; cp_build_addr_expr
7929 below expects an lvalue. */
7931 }
7934 {
7936 auto_diagnostic_group d;
7943 {
7946 {
7951 }
7958 extype);
7959 }
7961 {
7962 /* If we're converting from T[] to T[N], don't talk
7963 about discarding qualifiers. (Converting from T[N] to
7964 T[] is allowed by P0388R4.) */
7971 else
7974 }
7975 else
7981 }
7985 /* If necessary, create a temporary.
7987 VA_ARG_EXPR and CONSTRUCTOR expressions are special cases
7988 that need temporaries, even when their types are reference
7989 compatible with the type of reference being bound, so the
7990 upcoming call to cp_build_addr_expr doesn't fail. */
7994 {
7995 /* Otherwise, a temporary of type "cv1 T1" is created and
7996 initialized from the initializer expression using the rules
7997 for a non-reference copy-initialization (8.5). */
8005 {
8006 /* If the reference is volatile or non-const, we
8007 cannot create a temporary. */
8009 {
8016 else
8019 }
8021 }
8022 /* If the source is a packed field, and we must use a copy
8023 constructor, then building the target expr will require
8024 binding the field to the reference parameter to the
8025 copy constructor, and we'll end up with an infinite
8026 loop. If we can use a bitwise copy, then we'll be
8027 OK. */
8031 {
8035 }
8037 {
8040 }
8042 /* Creating &TARGET_EXPR<> in a template would break when
8043 tsubsting the expression, so use an IMPLICIT_CONV_EXPR
8044 instead. This can happen even when there's no class
8045 involved, e.g., when converting an integer to a reference
8046 type. */
8050 }
8052 /* Take the address of the thing to which we will bind the
8053 reference. */
8058 /* Convert it to a pointer to the type referred to by the
8059 reference. This will adjust the pointer if a derived to
8060 base conversion is being performed. */
8063 /* Convert the pointer to the desired reference type. */
8065 }
8071 /* ??? Should the address of a transaction-safe pointer point to the TM
8072 clone, and this conversion look up the primary function? */
8076 /* Warn about deprecated conversion if appropriate. */
8078 {
8081 }
8096 }
8106 else
8110 }
8112 /* Return true if converting FROM to TO is unsafe in a template. */
8114 static bool
8116 {
8117 /* Converting classes involves TARGET_EXPR. */
8121 /* Converting real to integer produces FIX_TRUNC_EXPR which tsubst
8122 doesn't handle. */
8126 /* Converting integer to real isn't a trivial conversion, either. */
8131 }
8133 /* Wrapper for convert_like_internal that handles creating
8134 IMPLICIT_CONV_EXPR. */
8136 static tree
8139 tsubst_flags_t complain)
8140 {
8141 /* Creating &TARGET_EXPR<> in a template breaks when substituting,
8142 and creating a CALL_EXPR in a template breaks in finish_call_expr
8143 so use an IMPLICIT_CONV_EXPR for this conversion. We would have
8144 created such codes e.g. when calling a user-defined conversion
8145 function. */
8150 {
8156 /* Do the normal processing to give the bad_p errors. But we still
8157 need to return the IMPLICIT_CONV_EXPR, unless we're returning
8158 error_mark_node. */
8159 }
8165 }
8167 /* Convenience wrapper for convert_like. */
8171 {
8175 }
8177 /* Convenience wrapper for convert_like. */
8181 tsubst_flags_t complain)
8182 {
8186 }
8188 /* ARG is being passed to a varargs function. Perform any conversions
8189 required. Return the converted value. */
8191 tree
8193 {
8197 /* [expr.call]
8199 If the argument has integral or enumeration type that is subject
8200 to the integral promotions (_conv.prom_), or a floating-point
8201 type that is subject to the floating-point promotion
8202 (_conv.fpprom_), the value of the argument is converted to the
8203 promoted type before the call. */
8208 {
8212 "implicit conversion from %qH to %qI when passing "
8217 }
8219 {
8222 {
8225 }
8226 else
8228 }
8230 {
8232 {
8234 complain);
8241 arg_type,
8245 }
8246 else
8248 }
8249 else
8250 /* [expr.call]
8252 The lvalue-to-rvalue, array-to-pointer, and function-to-pointer
8253 standard conversions are performed. */
8260 /* In a template (or ill-formed code), we can have an incomplete type
8261 even after require_complete_type_sfinae, in which case we don't know
8262 whether it has trivial copy or not. */
8265 {
8266 /* [expr.call] 5.2.2/7:
8267 Passing a potentially-evaluated argument of class type (Clause 9)
8268 with a non-trivial copy constructor or a non-trivial destructor
8269 with no corresponding parameter is conditionally-supported, with
8270 implementation-defined semantics.
8272 We support it as pass-by-invisible-reference, just like a normal
8273 value parameter.
8275 If the call appears in the context of a sizeof expression,
8276 it is not potentially-evaluated. */
8279 {
8283 "passing objects of non-trivially-copyable "
8285 arg_type);
8287 }
8288 /* Build up a real lvalue-to-rvalue conversion in case the
8289 copy constructor is trivial but not callable. */
8293 }
8296 }
8298 /* va_arg (EXPR, TYPE) is a builtin. Make sure it is not abused. */
8300 tree
8302 {
8304 {
8308 }
8318 {
8321 }
8325 {
8326 /* conditionally-supported behavior [expr.call] 5.2.2/7. Let's treat
8327 it as pass by invisible reference. */
8329 "receiving objects of non-trivially-copyable type %q#T "
8335 }
8339 /* Wrap the VA_ARG_EXPR in a TARGET_EXPR now so other code doesn't need to
8340 know how to handle it. */
8343 }
8345 /* TYPE has been given to va_arg. Apply the default conversions which
8346 would have happened when passed via ellipsis. Return the promoted
8347 type, or the passed type if there is no change. */
8349 tree
8351 {
8352 tree promote;
8354 /* Perform the array-to-pointer and function-to-pointer
8355 conversions. */
8363 }
8365 /* ARG is a default argument expression being passed to a parameter of
8366 the indicated TYPE, which is a parameter to FN. PARMNUM is the
8367 zero-based argument number. Do any required conversions. Return
8368 the converted value. */
8371 void
8375 void
8379 tree
8381 tsubst_flags_t complain)
8382 {
8384 tree t;
8386 /* See through clones. */
8388 /* And inheriting ctors. */
8392 /* Detect recursion. */
8395 {
8399 }
8401 /* If the ARG is an unparsed default argument expression, the
8402 conversion cannot be performed. */
8404 {
8409 }
8416 /* Due to:
8418 [dcl.fct.default]
8420 The names in the expression are bound, and the semantic
8421 constraints are checked, at the point where the default
8422 expressions appears.
8424 we must not perform access checks here. */
8426 /* We must make a copy of ARG, in case subsequent processing
8427 alters any part of it. */
8432 complain);
8439 }
8441 /* Returns the type which will really be used for passing an argument of
8442 type TYPE. */
8444 tree
8446 {
8447 /* Pass classes with copy ctors by invisible reference. */
8457 }
8459 /* Actually perform the appropriate conversion. */
8461 tree
8463 {
8464 tree bitfield_type;
8466 /* If VAL is a bitfield, then -- since it has already been converted
8467 to TYPE -- it cannot have a precision greater than TYPE.
8469 If it has a smaller precision, we must widen it here. For
8470 example, passing "int f:3;" to a function expecting an "int" will
8471 not result in any conversion before this point.
8473 If the precision is the same we must not risk widening. For
8474 example, the COMPONENT_REF for a 32-bit "long long" bitfield will
8475 often have type "int", even though the C++ type for the field is
8476 "long long". If the value is being passed to a function
8477 expecting an "int", then no conversions will be required. But,
8478 if we call convert_bitfield_to_declared_type, the bitfield will
8479 be converted to "long long". */
8486 ;
8487 /* Pass classes with copy ctors by invisible reference. */
8496 {
8498 {
8506 "argument of function call might be a candidate "
8508 }
8510 }
8516 }
8518 /* Returns non-zero iff FN is a function with magic varargs, i.e. ones for
8519 which just decay_conversion or no conversions at all should be done.
8520 This is true for some builtins which don't act like normal functions.
8521 Return 2 if no conversions at all should be done, 1 if just
8522 decay_conversion. Return 3 for special treatment of the 3rd argument
8523 for __builtin_*_overflow_p. */
8525 int
8527 {
8530 {
8545 }
8548 }
8550 /* Returns the decl of the dispatcher function if FN is a function version. */
8552 tree
8554 {
8567 {
8571 }
8576 }
8578 /* fn is a function version dispatcher that is marked used. Mark all the
8579 semantically identical function versions it will dispatch as used. */
8581 void
8583 {
8600 /* All semantically identical versions are chained. Traverse and mark each
8601 one of them as used. */
8604 {
8607 }
8608 }
8610 /* Build a call to "the copy constructor" for the type of A, even if it
8611 wouldn't be selected by normal overload resolution. Used for
8612 diagnostics. */
8614 static tree
8616 {
8626 }
8628 /* Return the base constructor corresponding to COMPLETE_CTOR or NULL_TREE. */
8630 static tree
8632 {
8633 tree clone;
8638 }
8640 /* Try to make EXP suitable to be used as the initializer for a base subobject,
8641 and return whether we were successful. EXP must have already been cleared
8642 by unsafe_copy_elision_p{,_opt}. */
8644 static bool
8646 {
8652 {
8655 {
8657 /* If unsafe_copy_elision_p was false, the arms should match. */
8659 }
8661 }
8663 /* A trivial copy is OK. */
8666 /* unsafe_copy_elision_p_opt must have said this is OK. */
8674 /* The base constructor has more parameters, so we can't just change the
8675 call target. It would be possible to splice in the appropriate
8676 arguments, but probably not worth the complexity. */
8680 }
8682 /* Return 2 if T refers to a base, 1 if a potentially-overlapping field,
8683 neither of which can be used for return by invisible reference. We avoid
8684 doing C++17 mandatory copy elision for either of these cases.
8686 This returns non-zero even if the type of T has no tail padding that other
8687 data could be allocated into, because that depends on the particular ABI.
8688 unsafe_copy_elision_p_opt does consider whether there is padding. */
8690 int
8692 {
8693 /* Check empty bases separately, they don't have fields. */
8705 /* The middle-end will do the right thing for scalar types. */
8712 }
8714 /* True IFF EXP is a prvalue that represents return by invisible reference. */
8716 static bool
8718 {
8719 /* Copy elision only happens with a TARGET_EXPR. */
8723 /* build_compound_expr pushes COMPOUND_EXPR inside TARGET_EXPR. */
8727 {
8728 /* We'll end up copying from each of the arms of the COND_EXPR directly
8729 into the target, so look at them. */
8734 }
8737 }
8739 /* We can't elide a copy from a function returning by value to a
8740 potentially-overlapping subobject, as the callee might clobber tail padding.
8741 Return true iff this could be that case.
8743 Places that use this function (or _opt) to decide to elide a copy should
8744 probably use make_safe_copy_elision instead. */
8746 static bool
8748 {
8750 }
8752 /* As above, but for optimization allow more cases that are actually safe. */
8754 static bool
8756 {
8758 /* It's safe to elide the copy for a class with no tail padding. */
8763 }
8765 /* Try to make EXP suitable to be used as the initializer for TARGET,
8766 and return whether we were successful. */
8768 bool
8770 {
8779 }
8781 /* True IFF the result of the conversion C is a prvalue. */
8783 static bool
8785 {
8797 }
8799 /* True iff C is a conversion that binds a reference to a prvalue. */
8801 static bool
8803 {
8810 }
8812 /* True iff converting EXPR to a reference type TYPE does not involve
8813 creating a temporary. */
8815 bool
8817 {
8820 /* Get the high-water mark for the CONVERSION_OBSTACK. */
8828 /* Free all the conversions we allocated. */
8832 }
8834 /* Call the trivial destructor for INSTANCE, which can be either an lvalue of
8835 class type or a pointer to class type. If NO_PTR_DEREF is true and
8836 INSTANCE has pointer type, clobber the pointer rather than what it points
8837 to. */
8839 tree
8841 {
8845 {
8846 no_clobber:
8848 }
8852 {
8856 }
8858 /* A trivial destructor should still clobber the object. */
8862 }
8864 /* Return true if a call to FN with number of arguments NARGS
8865 is an immediate invocation. */
8867 static bool
8869 {
8877 && !in_consteval_if_p
8878 /* As an exception, we defer std::source_location::current ()
8879 invocations until genericization because LWG3396 mandates
8880 special behavior for it. */
8882 }
8884 /* Subroutine of the various build_*_call functions. Overload resolution
8885 has chosen a winning candidate CAND; build up a CALL_EXPR accordingly.
8886 ARGS is a TREE_LIST of the unconverted arguments to the call. FLAGS is a
8887 bitmask of various LOOKUP_* flags which apply to the call itself. */
8889 static tree
8891 {
8899 tree val;
8908 /* In a template, there is no need to perform all of the work that
8909 is normally done. We are only interested in the type of the call
8910 expression, i.e., the return type of the function. Any semantic
8911 errors will be deferred until the template is instantiated. */
8913 {
8915 tree return_type;
8921 else
8922 /* Otherwise set TREE_USED for the benefit of -Wunused-function.
8923 See PR80598. */
8930 else
8931 {
8934 tree arg;
8942 }
8952 {
8959 {
8962 }
8963 /* Look through *(const T *)&obj. */
8965 {
8969 {
8974 }
8975 }
8978 obj_arg);
8979 }
8981 }
8983 /* Give any warnings we noticed during overload resolution. */
8985 {
8989 }
8991 /* Core issue 2327: P0135 doesn't say how to handle the case where the
8992 argument to the copy constructor ends up being a prvalue after
8993 conversion. Let's do the normal processing, but pretend we aren't
8994 actually using the copy constructor. */
9003 {
9006 }
9008 /* OK, we're actually calling this inherited constructor; set its deletedness
9009 appropriately. We can get away with doing this here because calling is
9010 the only way to refer to a constructor. */
9013 {
9017 }
9019 /* Make =delete work with SFINAE. */
9021 {
9025 }
9028 {
9029 tree access_fn;
9030 /* If FN is a template function, two cases must be considered.
9031 For example:
9033 struct A {
9034 protected:
9035 template <class T> void f();
9036 };
9037 template <class T> struct B {
9038 protected:
9039 void g();
9040 };
9041 struct C : A, B<int> {
9042 using A::f; // #1
9043 using B<int>::g; // #2
9044 };
9046 In case #1 where `A::f' is a member template, DECL_ACCESS is
9047 recorded in the primary template but not in its specialization.
9048 We check access of FN using its primary template.
9050 In case #2, where `B<int>::g' has a DECL_TEMPLATE_INFO simply
9051 because it is a member of class template B, DECL_ACCESS is
9052 recorded in the specialization `B<int>::g'. We cannot use its
9053 primary template because `B<T>::g' and `B<int>::g' may have
9054 different access. */
9058 else
9063 }
9065 /* If we're checking for implicit delete, don't bother with argument
9066 conversions. */
9068 {
9072 /* Reject bad conversions now. */
9074 /* else continue to get conversion error. */
9075 }
9077 not_really_used:
9079 /* N3276 magic doesn't apply to nested calls. */
9082 /* No-Cleanup doesn't apply to nested calls either. */
9086 /* Find maximum size of vector to hold converted arguments. */
9093 /* The implicit parameters to a constructor are not considered by overload
9094 resolution, and must be of the proper type. */
9096 {
9097 tree object_arg;
9099 {
9102 }
9103 else
9104 {
9107 }
9110 /* We should never try to call the abstract constructor. */
9114 {
9118 }
9122 {
9123 /* The implicit move specified in 15.8.3/3 fails "...if the type of
9124 the first parameter of the selected constructor is not an rvalue
9125 reference to the object's type (possibly cv-qualified)...." */
9128 /* Allow calling a by-value converting constructor even though it
9129 isn't permitted by the above, because we've allowed it since GCC 5
9130 (PR58051) and it's allowed in C++20. But don't call a copy
9131 constructor. */
9135 }
9136 }
9137 /* Bypass access control for 'this' parameter. */
9139 {
9141 ? first_arg
9149 {
9151 {
9152 auto_diagnostic_group d;
9157 }
9158 else
9160 }
9162 /* The class where FN is defined. */
9165 /* See if the function member or the whole class type is declared
9166 final and the call can be devirtualized. */
9170 /* [class.mfct.non-static]: If a non-static member function of a class
9171 X is called for an object that is not of type X, or of a type
9172 derived from X, the behavior is undefined.
9174 So we can assume that anything passed as 'this' is non-null, and
9175 optimize accordingly. */
9176 /* Check that the base class is accessible. */
9179 {
9184 else
9186 }
9187 /* If fn was found by a using declaration, the conversion path
9188 will be to the derived class, not the base declaring fn. We
9189 must convert to the base. */
9192 {
9196 }
9198 /* If we know the dynamic type of the object, look up the final overrider
9199 in the BINFO. */
9202 {
9205 /* And unwind base_binfo to match. If we don't find the type we're
9206 looking for in BINFO_INHERITANCE_CHAIN, we're looking at diamond
9207 inheritance; for now do a normal virtual call in that case. */
9213 {
9217 }
9218 }
9227 else
9231 }
9236 {
9243 /* If the argument is NULL and used to (implicitly) instantiate a
9244 template function (and bind one of the template arguments to
9245 the type of 'long int'), we don't want to warn about passing NULL
9246 to non-pointer argument.
9247 For example, if we have this template function:
9249 template<typename T> void func(T x) {}
9251 we want to warn (when -Wconversion is enabled) in this case:
9253 void foo() {
9254 func<int>(NULL);
9255 }
9257 but not in this case:
9259 void foo() {
9260 func(NULL);
9261 }
9262 */
9269 /* Set user_conv_p on the argument conversions, so rvalue/base handling
9270 knows not to allow any more UDCs. This needs to happen after we
9271 process cand->warnings. */
9280 arg_complain);
9285 else
9287 }
9289 /* Default arguments */
9291 {
9297 complain);
9301 }
9303 /* Ellipsis */
9306 {
9309 {
9310 /* Do no conversions for certain magic varargs. */
9314 }
9316 /* For other magic varargs only do decay_conversion. */
9321 {
9322 /* Avoid infinite recursion trying to call A(...). */
9324 /* Try to call the actual copy constructor for a good error. */
9327 }
9328 else
9333 }
9338 /* Avoid performing argument transformation if warnings are disabled.
9339 When tf_warning is set and at least one of the warnings is active
9340 the check_function_arguments function might warn about something. */
9344 && (warn_nonnull
9345 || warn_format
9346 || warn_suggest_attribute_format
9348 {
9352 {
9353 /* For -Wformat undo the implicit passing by hidden reference
9354 done by convert_arg_to_ellipsis. */
9358 else
9360 }
9364 }
9367 {
9368 /* Check for passing ellipsis arguments to an inherited constructor. We
9369 could handle this by open-coding the inherited constructor rather than
9370 defining it, but let's not bother now. */
9374 {
9376 {
9380 }
9382 }
9384 /* A base constructor inheriting from a virtual base doesn't get the
9385 inherited arguments, just this and __vtt. */
9388 }
9390 /* Avoid actually calling copy constructors and copy assignment operators,
9391 if possible. */
9398 /* It's unsafe to elide the constructor when handling
9399 a noexcept-expression, it may evaluate to the wrong
9400 value (c++/53025). */
9402 {
9403 tree targ;
9408 /* Pull out the real argument, disregarding const-correctness. */
9410 /* Strip the reference binding for the constructor parameter. */
9414 /* But don't strip any other reference bindings; binding a temporary to a
9415 reference prevents copy elision. */
9421 {
9426 }
9427 else
9432 else
9435 /* In C++17 we shouldn't be copying a TARGET_EXPR except into a
9436 potentially-overlapping subobject. */
9439 || force_elide
9440 /* It's from binding the ref parm to a packed field. */
9443 /* See unsafe_copy_elision_p. */
9449 /* [class.copy]: the copy constructor is implicitly defined even if the
9450 implementation elided its use. But don't warn about deprecation when
9451 eliding a temporary, as then no copy is actually performed. */
9456 {
9460 }
9461 else
9468 /* If we're creating a temp and we already have one, don't create a
9469 new one. If we're not creating a temp but we get one, use
9470 INIT_EXPR to collapse the temp into our target. Otherwise, if the
9471 ctor is trivial, do a bitwise copy with a simple TARGET_EXPR for a
9472 temp or an INIT_EXPR otherwise. */
9474 {
9479 }
9482 {
9486 }
9487 }
9491 {
9499 {
9500 /* Avoid copying empty classes. */
9503 }
9505 {
9509 "assignment from temporary %<initializer_list%> does "
9513 }
9514 else
9515 {
9516 /* We must only copy the non-tail padding parts. */
9525 build_index_type
9534 }
9539 }
9541 {
9545 {
9548 no_cleanup_complain);
9549 else
9551 }
9552 }
9560 /* Warn if the built-in writes to an object of a non-trivial type. */
9567 {
9568 tree t;
9575 complain);
9581 }
9582 else
9583 {
9584 /* If FN is marked deprecated, then we've already issued a deprecated-use
9585 warning from mark_used above, so avoid redundantly issuing another one
9586 from build_addr_func. */
9592 }
9598 {
9600 /* build_new_op_1 will clear this when appropriate. */
9602 }
9604 {
9608 }
9610 {
9613 {
9615 /* Undo convert_from_reference called by build_cxx_call. */
9621 {
9624 }
9625 /* Look through *(const T *)&obj. */
9627 {
9631 {
9636 }
9637 }
9642 }
9643 }
9645 }
9647 namespace
9648 {
9650 /* Return the DECL of the first non-static subobject of class TYPE
9651 that satisfies the predicate PRED or null if none can be found. */
9654 tree
9656 {
9661 {
9668 }
9674 {
9680 }
9683 }
9685 struct NonPublicField
9686 {
9688 {
9690 }
9691 };
9693 /* Return the DECL of the first non-public subobject of class TYPE
9694 or null if none can be found. */
9698 {
9700 }
9702 struct NonTrivialField
9703 {
9705 {
9707 }
9708 };
9710 /* Return the DECL of the first non-trivial subobject of class TYPE
9711 or null if none can be found. */
9715 {
9717 }
9721 /* Return true if all copy and move assignment operator overloads for
9722 class TYPE are trivial and at least one of them is not deleted and,
9723 when ACCESS is set, accessible. Return false otherwise. Set
9724 HASASSIGN to true when the TYPE has a (not necessarily trivial)
9725 copy or move assignment. */
9727 static bool
9729 {
9733 /* Iterate over overloads of the assignment operator, checking
9734 accessible copy assignments for triviality. */
9737 {
9738 /* Skip operators that aren't copy assignments. */
9745 /* Skip template assignment operators and deleted functions. */
9755 /* Break early when both properties have been determined. */
9758 }
9760 /* Return true if they're all trivial and one of the expressions
9761 TYPE() = TYPE() or TYPE() = (TYPE&)() is valid. */
9766 }
9768 /* Return true if all copy and move ctor overloads for class TYPE are
9769 trivial and at least one of them is not deleted and, when ACCESS is
9770 set, accessible. Return false otherwise. Set each element of HASCTOR[]
9771 to true when the TYPE has a (not necessarily trivial) default and copy
9772 (or move) ctor, respectively. */
9774 static bool
9776 {
9781 {
9782 /* Skip template constructors. */
9788 /* Skip ctors other than default, copy, and move. */
9804 /* Break early when both properties have been determined. */
9807 }
9810 }
9812 /* Issue a warning on a call to the built-in function FNDECL if it is
9813 a raw memory write whose destination is not an object of (something
9814 like) trivial or standard layout type with a non-deleted assignment
9815 and copy ctor. Detects const correctness violations, corrupting
9816 references, virtual table pointers, and bypassing non-trivial
9817 assignments. */
9819 static void
9822 {
9823 /* Except for bcopy where it's second, the destination pointer is
9824 the first argument for all functions handled here. Compute
9825 the index of the destination and source arguments. */
9837 /* Determine the type of the pointed-to object and whether it's
9838 a complete class type. */
9844 /* Check to see if the raw memory call is made by a non-static member
9845 function with THIS as the destination argument for the destination
9846 type. If so, and if the class has no non-trivial bases or members,
9847 be more permissive. */
9851 {
9860 }
9862 /* True if the class is trivial. */
9865 /* Set to true if DESTYPE has an accessible copy assignment. */
9867 /* True if all of the class' overloaded copy assignment operators
9868 are all trivial (and not deleted) and at least one of them is
9869 accessible. */
9872 /* Set to true if DESTTYPE has an accessible default and copy ctor,
9873 respectively. */
9876 /* True if all of the class' overloaded copy constructors are all
9877 trivial (and not deleted) and at least one of them is accessible. */
9880 /* Set FLD to the first private/protected member of the class. */
9883 /* The warning format string. */
9885 /* A suggested alternative to offer instead of the raw memory call.
9886 Empty string when none can be come up with. */
9891 {
9894 {
9895 /* Diagnose setting non-copy-assignable or non-trivial types,
9896 or types with a private member, to (potentially) non-zero
9897 bytes. Since the value of the bytes being written is unknown,
9898 suggest using assignment instead (if one exists). Also warn
9899 for writes into objects for which zero-initialization doesn't
9900 mean all bits clear (pointer-to-member data, where null is all
9901 bits set). Since the value being written is (most likely)
9902 non-zero, simply suggest assignment (but not copy assignment). */
9910 {
9913 "%qD writing to an object of type %#qT with "
9916 }
9922 }
9923 /* Fall through. */
9926 /* Similarly to the above, diagnose clearing non-trivial or non-
9927 standard layout objects, or objects of types with no assignmenmt.
9928 Since the value being written is known to be zero, suggest either
9929 copy assignment, copy ctor, or default ctor as an alternative,
9930 depending on what's available. */
9953 /* Determine the type of the source object. */
9957 else
9960 /* Since it's impossible to determine wheter the byte copy is
9961 being used in place of assignment to an existing object or
9962 as a substitute for initialization, assume it's the former.
9963 Determine the best alternative to use instead depending on
9964 what's not deleted. */
9985 srctype))
9986 {
9987 /* Warn when copying into a non-trivial object from an object
9988 of a different type other than void or char. */
9990 "%qD copying an object of non-trivial type "
9993 }
9998 srctype))
9999 {
10002 "%qD copying an object of type %#qT with "
10003 "%qs member %qD from an array of %#qT; use "
10006 }
10008 {
10013 /* Finally, warn on partial copies. */
10014 unsigned HOST_WIDE_INT typesize
10020 "a non-trivial type %#qT leaves %wu "
10023 "a non-trivial type %#qT leaves %wu "
10026 }
10041 {
10045 /* Finally, warn on reallocation into insufficient space. */
10047 "%qD moving an object of non-trivial type "
10050 sz);
10051 }
10056 }
10059 {
10063 else
10066 }
10070 }
10072 /* Build and return a call to FN, using NARGS arguments in ARGARRAY.
10073 If FN is the result of resolving an overloaded target built-in,
10074 ORIG_FNDECL is the original function decl, otherwise it is null.
10075 This function performs no overload resolution, conversion, or other
10076 high-level operations. */
10078 tree
10081 {
10082 tree fndecl;
10084 /* Remember roughly where this call is. */
10093 /* Check that arguments to builtin functions match the expectations. */
10095 && !processing_template_decl
10097 {
10100 /* We need to take care that values to BUILT_IN_NORMAL
10101 are reduced. */
10108 }
10113 /* 5.2.2/11: If a function call is a prvalue of object type: if the
10114 function call is either the operand of a decltype-specifier or the
10115 right operand of a comma operator that is the operand of a
10116 decltype-specifier, a temporary object is not introduced for the
10117 prvalue. The type of the prvalue may be incomplete. */
10119 {
10125 {
10128 }
10129 }
10131 }
10133 /* Returns the value to use for the in-charge parameter when making a
10134 call to a function with the indicated NAME.
10136 FIXME:Can't we find a neater way to do this mapping? */
10138 tree
10140 {
10142 {
10146 }
10147 else
10148 {
10154 }
10157 }
10159 /* We've built up a constructor call RET. Complain if it delegates to the
10160 constructor we're currently compiling. */
10162 static void
10164 {
10170 }
10172 /* Build a call to a constructor, destructor, or an assignment
10173 operator for INSTANCE, an expression with class type. NAME
10174 indicates the special member function to call; *ARGS are the
10175 arguments. ARGS may be NULL. This may change ARGS. BINFO
10176 indicates the base of INSTANCE that is to be passed as the `this'
10177 parameter to the member function called.
10179 FLAGS are the LOOKUP_* flags to use when processing the call.
10181 If NAME indicates a complete object constructor, INSTANCE may be
10182 NULL_TREE. In this case, the caller will call build_cplus_new to
10183 store the newly constructed object into a VAR_DECL. */
10185 tree
10188 {
10189 tree fns;
10190 /* The type of the subobject to be constructed or destroyed. */
10191 tree class_type;
10193 tree ret;
10201 {
10204 /* Shortcut to avoid lazy destructor declaration. */
10206 }
10209 {
10210 /* Resolve the name. */
10215 }
10221 /* Handle the special case where INSTANCE is NULL_TREE. */
10224 else
10225 {
10226 /* Convert to the base class, if necessary. */
10229 {
10231 /* For constructors and destructors, either the base is
10232 non-virtual, or it is virtual but we are doing the
10233 conversion from a constructor or destructor for the
10234 complete object. In either case, we can convert
10235 statically. */
10237 else
10238 {
10239 /* However, for assignment operators, we must convert
10240 dynamically if the base is virtual. */
10244 }
10245 }
10246 }
10250 /* In C++17, "If the initializer expression is a prvalue and the
10251 cv-unqualified version of the source type is the same class as the class
10252 of the destination, the initializer expression is used to initialize the
10253 destination object." Handle that here to avoid doing overload
10254 resolution. */
10258 {
10269 && (same_type_ignoring_top_level_qualifiers_p
10271 {
10280 /* Avoid change of behavior on Wunused-var-2.C. */
10283 }
10284 }
10288 /* When making a call to a constructor or destructor for a subobject
10289 that uses virtual base classes, pass down a pointer to a VTT for
10290 the subobject. */
10294 {
10295 tree vtt;
10296 tree sub_vtt;
10298 /* If the current function is a complete object constructor
10299 or destructor, then we fetch the VTT directly.
10300 Otherwise, we look it up using the VTT we were given. */
10308 else
10312 {
10315 }
10318 }
10323 complain);
10334 }
10336 /* Return the NAME, as a C string. The NAME indicates a function that
10337 is a member of TYPE. *FREE_P is set to true if the caller must
10338 free the memory returned.
10340 Rather than go through all of this, we should simply set the names
10341 of constructors and destructors appropriately, and dispense with
10342 ctor_identifier, dtor_identifier, etc. */
10346 {
10349 /* Assume that we will not allocate memory. */
10351 /* Constructors and destructors are special. */
10353 {
10354 pretty_name
10356 /* For a destructor, add the '~'. */
10358 {
10360 /* Remember that we need to free the memory allocated. */
10362 }
10363 }
10365 {
10368 TFF_PLAIN_IDENTIFIER),
10369 NULL);
10370 /* Remember that we need to free the memory allocated. */
10372 }
10373 else
10377 }
10379 /* If CANDIDATES contains exactly one candidate, return it, otherwise
10380 return NULL. */
10384 {
10392 }
10394 /* If CANDIDATE is invalid due to a bad argument type, return the
10395 pertinent conversion_info.
10397 Otherwise, return NULL. */
10401 {
10402 /* Must be an rr_arg_conversion or rr_bad_arg_conversion. */
10409 {
10418 }
10419 }
10421 /* Issue an error and note complaining about a bad argument type at a
10422 callsite with a single candidate FNDECL.
10424 ARG_LOC is the location of the argument (or UNKNOWN_LOCATION, in which
10425 case input_location is used).
10426 FROM_TYPE is the type of the actual argument; TO_TYPE is the type of
10427 the formal parameter. */
10429 void
10433 {
10434 auto_diagnostic_group d;
10438 {
10441 }
10447 parmnum);
10448 }
10450 /* Subroutine of build_new_method_call_1, for where there are no viable
10451 candidates for the call. */
10453 static void
10456 tree explicit_targs,
10457 tree basetype,
10461 {
10462 auto_diagnostic_group d;
10469 else
10470 {
10471 /* Special-case for when there's a single candidate that's failing
10472 due to a bad argument type. */
10476 {
10484 }
10490 {
10493 }
10501 }
10503 }
10505 /* Build a call to "INSTANCE.FN (ARGS)". If FN_P is non-NULL, it will
10506 be set, upon return, to the function called. ARGS may be NULL.
10507 This may change ARGS. */
10509 static tree
10513 {
10517 tree access_binfo;
10518 tree optype;
10520 tree name;
10523 tree call;
10524 tree fn;
10527 tree orig_instance;
10528 tree orig_fns;
10534 /* We don't know what function we're going to call, yet. */
10543 {
10547 }
10552 /* Dismantle the baselink to collect all the information we need. */
10559 {
10563 }
10572 /* Under DR 147 A::A() is an invalid constructor call,
10573 not a functional cast. */
10575 {
10581 auto_diagnostic_group d;
10589 complain);
10591 }
10594 {
10599 }
10601 /* Process the argument list. */
10603 {
10608 }
10610 /* Consider the object argument to be used even if we end up selecting a
10611 static member function. */
10614 /* Figure out whether to skip the first argument for the error
10615 message we will display to users if an error occurs. We don't
10616 want to display any compiler-generated arguments. The "this"
10617 pointer hasn't been added yet. However, we must remove the VTT
10618 pointer if this is a call to a base-class constructor or
10619 destructor. */
10622 {
10623 /* Callers should explicitly indicate whether they want to ctor
10624 the complete object or just the part without virtual bases. */
10627 /* Remove the VTT pointer, if present. */
10632 /* It's OK to call destructors and constructors on cv-qualified
10633 objects. Therefore, convert the INSTANCE to the unqualified
10634 type, if necessary. */
10636 {
10640 }
10641 }
10642 else
10645 /* For the overload resolution we need to find the actual `this`
10646 that would be captured if the call turns out to be to a
10647 non-static member function. Do not actually capture it at this
10648 point. */
10650 /* Constructors don't use the enclosing 'this'. */
10652 else
10655 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10658 /* The number of arguments artificial parms in ARGS; we subtract one because
10659 there's no 'this' in ARGS. */
10662 /* If CONSTRUCTOR_IS_DIRECT_INIT is set, this was a T{ } form
10663 initializer, not T({ }). */
10667 {
10674 /* If the initializer list has no elements and T is a class type with
10675 a default constructor, the object is value-initialized. Handle
10676 this here so we don't need to handle it wherever we use
10677 build_special_member_call. */
10680 /* For a user-provided default constructor, use the normal
10681 mechanisms so that protected access works. */
10686 /* If BASETYPE is an aggregate, we need to do aggregate
10687 initialization. */
10689 {
10692 }
10695 {
10701 }
10703 /* Otherwise go ahead with overload resolution. */
10708 }
10709 else
10718 {
10719 /* [dcl.init], 17.6.2.2:
10721 Otherwise, if no constructor is viable, the destination type is
10722 a (possibly cv-qualified) aggregate class A, and the initializer
10723 is a parenthesized expression-list, the object is initialized as
10724 follows...
10726 We achieve this by building up a CONSTRUCTOR, as for list-init,
10727 and setting CONSTRUCTOR_IS_PAREN_INIT to distinguish between
10728 the two. */
10734 {
10735 /* Create a CONSTRUCTOR from ARGS, e.g. {1, 2} from <1, 2>. */
10737 user_args);
10742 else
10743 {
10750 }
10751 }
10756 skip_first_for_error,
10757 user_args);
10759 }
10760 else
10761 {
10764 {
10767 tree arglist;
10770 {
10775 auto_diagnostic_group d;
10779 else
10785 }
10789 }
10790 else
10791 {
10799 {
10800 /* This is not an error, it is runtime undefined
10801 behavior. */
10810 fn);
10811 }
10816 {
10821 {
10822 /* We captured 'this' in the current lambda now that
10823 we know we really need it. */
10825 }
10827 /* We can't tell until instantiation time whether we can use
10829 else
10830 {
10833 fn);
10835 }
10836 }
10839 {
10840 /* Now we know what function is being called. */
10843 /* Build the actual CALL_EXPR. */
10845 /* In an expression of the form `a->f()' where `f' turns
10846 out to be a static member function, `a' is
10847 none-the-less evaluated. */
10851 {
10852 /* But avoid the implicit lvalue-rvalue conversion when 'a'
10853 is volatile. */
10859 }
10863 /* An explicit call of the form "x->~X()" has type
10864 "void". However, on platforms where destructors
10865 return "this" (i.e., those where
10866 targetm.cxx.cdtor_returns_this is true), such calls
10867 will appear to have a return value of pointer type
10868 to the low-level call machinery. We do not want to
10869 change the low-level machinery, since we want to be
10870 able to optimize "delete f()" on such platforms as
10871 "operator delete(~X(f()))" (rather than generating
10872 "t = f(), ~X(t), operator delete (t)"). */
10874 }
10875 }
10876 }
10879 {
10885 {
10888 }
10891 call = (build_min_non_dep_call_vec
10895 orig_args));
10900 }
10902 /* Free all the conversions we allocated. */
10909 }
10911 /* Wrapper for above. */
10913 tree
10917 {
10918 tree ret;
10924 }
10926 /* Returns true iff standard conversion sequence ICS1 is a proper
10927 subsequence of ICS2. */
10929 static bool
10931 {
10932 /* We can assume that a conversion of the same code
10933 between the same types indicates a subsequence since we only get
10934 here if the types we are converting from are the same. */
10941 {
10948 /* At this point, ICS1 cannot be a proper subsequence of
10949 ICS2. We can get a USER_CONV when we are comparing the
10950 second standard conversion sequence of two user conversion
10951 sequences. */
10966 }
10967 }
10969 /* Returns nonzero iff DERIVED is derived from BASE. The inputs may
10970 be any _TYPE nodes. */
10972 bool
10974 {
10978 /* We only allow proper derivation here. The DERIVED_FROM_P macro
10979 considers every class derived from itself. */
10982 }
10984 /* We build the ICS for an implicit object parameter as a pointer
10985 conversion sequence. However, such a sequence should be compared
10986 as if it were a reference conversion sequence. If ICS is the
10987 implicit conversion sequence for an implicit object parameter,
10988 modify it accordingly. */
10990 static void
10992 {
10994 {
10995 /* [over.match.funcs]
10997 For non-static member functions, the type of the
10998 implicit object parameter is "reference to cv X"
10999 where X is the class of which the function is a
11000 member and cv is the cv-qualification on the member
11001 function declaration. */
11003 tree reference_type;
11005 /* The `this' parameter is a pointer to a class type. Make the
11006 implicit conversion talk about a reference to that same class
11007 type. */
11020 }
11021 }
11023 /* If *ICS is a REF_BIND set *ICS to the remainder of the conversion,
11024 and return the initial reference binding conversion. Otherwise,
11025 leave *ICS unchanged and return NULL. */
11029 {
11031 {
11036 }
11039 }
11041 /* Get the expression at the beginning of the conversion chain C. */
11043 static tree
11045 {
11050 }
11052 /* Return a tree representing the number of elements initialized by the
11053 list-initialization C. The caller must check that C converts to an
11054 array type. */
11056 static tree
11058 {
11059 /* If the array we're converting to has a dimension, we'll use that. */
11062 else
11063 {
11064 /* Otherwise, we look at how many elements the constructor we're
11065 initializing from has. */
11068 }
11069 }
11071 /* True iff C is a conversion that binds a reference or a pointer to
11072 an array of unknown bound. */
11076 {
11077 /* ck_ref_bind won't have the reference stripped. */
11079 /* ck_qual won't have the pointer stripped. */
11083 }
11085 /* Compare two implicit conversion sequences according to the rules set out in
11086 [over.ics.rank]. Return values:
11088 1: ics1 is better than ics2
11089 -1: ics2 is better than ics1
11090 0: ics1 and ics2 are indistinguishable */
11092 static int
11094 {
11095 tree from_type1;
11096 tree from_type2;
11097 tree to_type1;
11098 tree to_type2;
11105 /* REF_BINDING is nonzero if the result of the conversion sequence
11106 is a reference type. In that case REF_CONV is the reference
11107 binding conversion. */
11111 /* Compare badness before stripping the reference conversion. */
11117 /* Handle implicit object parameters. */
11121 /* Handle reference parameters. */
11125 /* List-initialization sequence L1 is a better conversion sequence than
11126 list-initialization sequence L2 if L1 converts to
11127 std::initializer_list<X> for some X and L2 does not. */
11133 /* [over.ics.rank]
11135 When comparing the basic forms of implicit conversion sequences (as
11136 defined in _over.best.ics_)
11138 --a standard conversion sequence (_over.ics.scs_) is a better
11139 conversion sequence than a user-defined conversion sequence
11140 or an ellipsis conversion sequence, and
11142 --a user-defined conversion sequence (_over.ics.user_) is a
11143 better conversion sequence than an ellipsis conversion sequence
11144 (_over.ics.ellipsis_). */
11145 /* Use BAD_CONVERSION_RANK because we already checked for a badness
11146 mismatch. If both ICS are bad, we try to make a decision based on
11147 what would have happened if they'd been good. This is not an
11148 extension, we'll still give an error when we build up the call; this
11149 just helps us give a more helpful error message. */
11159 /* Both conversions are ellipsis conversions. */
11162 /* User-defined conversion sequence U1 is a better conversion sequence
11163 than another user-defined conversion sequence U2 if they contain the
11164 same user-defined conversion operator or constructor and if the sec-
11165 ond standard conversion sequence of U1 is better than the second
11166 standard conversion sequence of U2. */
11168 /* Handle list-conversion with the same code even though it isn't always
11169 ranked as a user-defined conversion and it doesn't have a second
11170 standard conversion sequence; it will still have the desired effect.
11171 Specifically, we need to do the reference binding comparison at the
11172 end of this function. */
11176 {
11183 {
11188 }
11189 /* List-initialization sequence L1 is a better conversion sequence than
11190 list-initialization sequence L2 if
11192 -- L1 and L2 convert to arrays of the same element type, and either
11193 the number of elements n1 initialized by L1 is less than the number
11194 of elements n2 initialized by L2, or n1=n2 and L2 converts to an array
11195 of unknown bound and L1 does not. (Added in CWG 1307 and extended by
11196 P0388R4.) */
11200 {
11201 /* The type of the array elements must be the same. */
11211 /* The n1 == n2 case. */
11218 else
11220 }
11221 else
11222 {
11223 /* For ambiguous or aggregate conversions, use the target type as
11224 a proxy for the conversion function. */
11227 }
11229 /* We can just fall through here, after setting up
11230 FROM_TYPE1 and FROM_TYPE2. */
11233 }
11234 else
11235 {
11239 /* We're dealing with two standard conversion sequences.
11241 [over.ics.rank]
11243 Standard conversion sequence S1 is a better conversion
11244 sequence than standard conversion sequence S2 if
11246 --S1 is a proper subsequence of S2 (comparing the conversion
11247 sequences in the canonical form defined by _over.ics.scs_,
11248 excluding any Lvalue Transformation; the identity
11249 conversion sequence is considered to be a subsequence of
11250 any non-identity conversion sequence */
11261 }
11263 /* One sequence can only be a subsequence of the other if they start with
11264 the same type. They can start with different types when comparing the
11265 second standard conversion sequence in two user-defined conversion
11266 sequences. */
11268 {
11273 }
11275 /* [over.ics.rank]
11277 Or, if not that,
11279 --the rank of S1 is better than the rank of S2 (by the rules
11280 defined below):
11282 Standard conversion sequences are ordered by their ranks: an Exact
11283 Match is a better conversion than a Promotion, which is a better
11284 conversion than a Conversion.
11286 Two conversion sequences with the same rank are indistinguishable
11287 unless one of the following rules applies:
11289 --A conversion that does not a convert a pointer, pointer to member,
11290 or std::nullptr_t to bool is better than one that does.
11292 The ICS_STD_RANK automatically handles the pointer-to-bool rule,
11293 so that we do not have to check it explicitly. */
11302 /* A conversion from scalar arithmetic type to complex is worse than a
11303 conversion between scalar arithmetic types. */
11310 {
11313 else
11315 }
11321 {
11326 }
11327 /* The rules for pointers to members A::* are just like the rules
11328 for pointers A*, except opposite: if B is derived from A then
11329 A::* converts to B::*, not vice versa. For that reason, we
11330 switch the from_ and to_ variables here. */
11337 {
11342 }
11347 {
11348 /* This was one of the pointer or pointer-like conversions.
11350 [over.ics.rank]
11352 --If class B is derived directly or indirectly from class A,
11353 conversion of B* to A* is better than conversion of B* to
11354 void*, and conversion of A* to void* is better than
11355 conversion of B* to void*. */
11358 {
11360 deref_from_type2))
11363 deref_from_type1))
11365 }
11368 {
11370 {
11372 {
11374 deref_to_type1))
11376 }
11377 /* We know that DEREF_TO_TYPE1 is `void' here. */
11379 deref_to_type2))
11381 }
11382 }
11385 {
11386 /* [over.ics.rank]
11388 --If class B is derived directly or indirectly from class A
11389 and class C is derived directly or indirectly from B,
11391 --conversion of C* to B* is better than conversion of C* to
11392 A*,
11394 --conversion of B* to A* is better than conversion of C* to
11395 A* */
11397 {
11399 deref_to_type2))
11402 deref_to_type1))
11404 }
11406 {
11408 deref_from_type1))
11411 deref_from_type2))
11413 }
11414 }
11415 }
11418 {
11421 /* [over.ics.rank]
11423 --binding of an expression of type C to a reference of type
11424 B& is better than binding an expression of type C to a
11425 reference of type A&
11427 --conversion of C to B is better than conversion of C to A, */
11430 {
11435 }
11436 }
11439 {
11442 /* [over.ics.rank]
11444 --binding of an expression of type B to a reference of type
11445 A& is better than binding an expression of type C to a
11446 reference of type A&,
11448 --conversion of B to A is better than conversion of C to A */
11451 {
11456 }
11457 }
11459 /* [over.ics.rank]
11461 --S1 and S2 differ only in their qualification conversion and yield
11462 similar types T1 and T2 (_conv.qual_), respectively, and the cv-
11463 qualification signature of type T1 is a proper subset of the cv-
11464 qualification signature of type T2 */
11468 {
11472 }
11474 /* [over.ics.rank]
11476 --S1 and S2 are reference bindings (_dcl.init.ref_) and neither refers
11477 to an implicit object parameter of a non-static member function
11478 declared without a ref-qualifier, and either S1 binds an lvalue
11479 reference to an lvalue and S2 binds an rvalue reference or S1 binds an
11480 rvalue reference to an rvalue and S2 binds an lvalue reference (C++0x
11481 draft standard, 13.3.3.2)
11483 --S1 and S2 are reference bindings (_dcl.init.ref_), and the
11484 types to which the references refer are the same type except for
11485 top-level cv-qualifiers, and the type to which the reference
11486 initialized by S2 refers is more cv-qualified than the type to
11487 which the reference initialized by S1 refers.
11489 DR 1328 [over.match.best]: the context is an initialization by
11490 conversion function for direct reference binding (13.3.1.6) of a
11491 reference to function type, the return type of F1 is the same kind of
11492 reference (i.e. lvalue or rvalue) as the reference being initialized,
11493 and the return type of F2 is not. */
11496 {
11503 {
11507 /* Don't prefer a bad conversion that drops cv-quals to a bad
11508 conversion with the wrong rvalueness. */
11512 }
11515 {
11516 /* Per P0388R4:
11518 void f (int(&)[]), // (1)
11519 f (int(&)[1]), // (2)
11520 f (int*); // (3)
11522 (2) is better than (1), but (3) should be equal to (1) and to
11523 (2). For that reason we don't use ck_qual for (1) which would
11524 give it the cr_exact rank while (3) remains ck_identity.
11525 Therefore we compare (1) and (2) here. For (1) we'll have
11527 ck_ref_bind <- ck_identity
11528 int[] & int[1]
11530 so to handle this we must look at ref_conv. */
11541 {
11542 /* Prefer the one that drops fewer cv-quals. */
11547 }
11549 }
11550 }
11552 /* [over.ics.rank]
11554 Per CWG 1601:
11555 -- A conversion that promotes an enumeration whose underlying type
11556 is fixed to its underlying type is better than one that promotes to
11557 the promoted underlying type, if the two are different. */
11563 {
11567 {
11574 }
11575 }
11577 /* Neither conversion sequence is better than the other. */
11579 }
11581 /* The source type for this standard conversion sequence. */
11583 static tree
11585 {
11587 }
11589 /* Note a warning about preferring WINNER to LOSER. We do this by storing
11590 a pointer to LOSER and re-running joust to produce the warning if WINNER
11591 is actually used. */
11593 static void
11595 {
11601 }
11603 /* CAND is a constructor candidate in joust in C++17 and up. If it copies a
11604 prvalue returned from a conversion function, replace CAND with the candidate
11605 for the conversion and return true. Otherwise, return false. */
11607 static bool
11609 {
11617 {
11622 {
11625 }
11626 }
11628 }
11630 /* True if the defining declarations of the two candidates have equivalent
11631 parameters. */
11633 bool
11635 {
11642 /* We don't look at c1->template_decl because that's only set for primary
11643 templates, not e.g. non-template member functions of class templates. */
11647 {
11654 }
11657 }
11659 /* Compare two candidates for overloading as described in
11660 [over.match.best]. Return values:
11662 1: cand1 is better than cand2
11663 -1: cand2 is better than cand1
11664 0: cand1 and cand2 are indistinguishable */
11666 static int
11668 tsubst_flags_t complain)
11669 {
11675 /* Candidates that involve bad conversions are always worse than those
11676 that don't. */
11682 /* If we have two pseudo-candidates for conversions to the same type,
11683 or two candidates for the same function, arbitrarily pick one. */
11689 /* Prefer a non-deleted function over an implicitly deleted move
11690 constructor or assignment operator. This differs slightly from the
11691 wording for issue 1402 (which says the move op is ignored by overload
11692 resolution), but this way produces better error messages. */
11696 {
11703 }
11705 /* a viable function F1
11706 is defined to be a better function than another viable function F2 if
11707 for all arguments i, ICSi(F1) is not a worse conversion sequence than
11708 ICSi(F2), and then */
11710 /* for some argument j, ICSj(F1) is a better conversion sequence than
11711 ICSj(F2) */
11713 /* For comparing static and non-static member functions, we ignore
11714 the implicit object parameter of the non-static function. The
11715 standard says to pretend that the static function has an object
11716 parm, but that won't work with operator overloading. */
11719 {
11725 /* We're comparing a near-match list constructor and a near-match
11726 non-list constructor. Just treat them as unordered. */
11733 else
11734 {
11737 }
11738 }
11740 /* Handle C++17 copy elision in [over.match.ctor] (direct-init) context. The
11741 standard currently says that only constructors are candidates, but if one
11742 copies a prvalue returned by a conversion function we want to treat the
11743 conversion as the candidate instead.
11745 Clang does something similar, as discussed at
11746 http://lists.isocpp.org/core/2017/10/3166.php
11747 http://lists.isocpp.org/core/2019/03/5721.php */
11753 {
11756 /* As a tiebreaker below we will prefer a constructor to a conversion
11757 operator exposed this way. */
11759 }
11762 {
11768 {
11770 && warn_sign_promo
11782 {
11789 else
11794 {
11798 }
11799 else
11801 }
11804 {
11805 /* Ambiguity between normal and reversed comparison operators
11806 with the same parameter types; prefer the normal one. */
11813 }
11815 }
11816 }
11818 /* warn about confusing overload resolution for user-defined conversions,
11819 either between a constructor and a conversion op, or between two
11820 conversion ops. */
11822 /* In C++17, the constructor might have been elided, which means that
11823 an originally null ->second_conv could become non-null. */
11827 {
11833 else
11836 /* We don't want to complain about `X::operator T1 ()'
11837 beating `X::operator T2 () const', when T2 is a no less
11838 cv-qualified version of T1. */
11841 {
11846 {
11849 }
11852 }
11853 else
11859 {
11863 auto_diagnostic_group d;
11867 {
11870 }
11871 }
11872 else
11874 }
11879 /* Put this tiebreaker first, so that we don't try to look at second_conv of
11880 a constructor candidate that doesn't have one. */
11884 /* DR 495 moved this tiebreaker above the template ones. */
11885 /* or, if not that,
11886 the context is an initialization by user-defined conversion (see
11887 _dcl.init_ and _over.match.user_) and the standard conversion
11888 sequence from the return type of F1 to the destination type (i.e.,
11889 the type of the entity being initialized) is a better conversion
11890 sequence than the standard conversion sequence from the return type
11891 of F2 to the destination type. */
11894 {
11898 }
11900 /* or, if not that,
11901 F1 is a non-template function and F2 is a template function
11902 specialization. */
11909 /* or, if not that,
11910 F1 and F2 are template functions and the function template for F1 is
11911 more specialized than the template for F2 according to the partial
11912 ordering rules. */
11915 {
11916 winner = more_specialized_fn
11919 /* [temp.func.order]: The presence of unused ellipsis and default
11920 arguments has no effect on the partial ordering of function
11921 templates. add_function_candidate() will not have
11922 counted the "this" argument for constructors. */
11926 }
11928 /* Concepts: F1 and F2 are non-template functions with the same
11929 parameter-type-lists, and F1 is more constrained than F2 according to the
11930 partial ordering of constraints described in 13.5.4. */
11935 {
11939 }
11941 /* F2 is a rewritten candidate (12.4.1.2) and F1 is not, or F1 and F2 are
11942 rewritten candidates, and F2 is a synthesized candidate with reversed
11943 order of parameters and F1 is not. */
11945 {
11952 }
11956 /* F1 is generated from a deduction-guide (13.3.1.8) and F2 is not */
11958 {
11960 /* We distinguish between candidates from an explicit deduction guide and
11961 candidates built from a constructor based on DECL_ARTIFICIAL. */
11968 {
11969 /* Prefer the special copy guide over a declared copy/move
11970 constructor. */
11976 /* Prefer a candidate generated from a non-template constructor. */
11981 }
11982 }
11984 /* F1 is a member of a class D, F2 is a member of a base class B of D, and
11985 for all arguments the corresponding parameters of F1 and F2 have the same
11986 type (CWG 2273/2277). */
11991 {
12005 {
12007 {
12012 }
12015 }
12016 }
12018 /* Check whether we can discard a builtin candidate, either because we
12019 have two identical ones or matching builtin and non-builtin candidates.
12021 (Pedantically in the latter case the builtin which matched the user
12022 function should not be added to the overload set, but we spot it here.
12024 [over.match.oper]
12025 ... the builtin candidates include ...
12026 - do not have the same parameter type list as any non-template
12027 non-member candidate. */
12030 {
12036 {
12038 /* Two built-in candidates; arbitrarily pick one. */
12041 /* cand1 is built-in; prefer cand2. */
12043 else
12044 /* cand2 is built-in; prefer cand1. */
12046 }
12047 }
12049 /* For candidates of a multi-versioned function, make the version with
12050 the highest priority win. This version will be checked for dispatching
12051 first. If this version can be inlined into the caller, the front-end
12052 will simply make a direct call to this function. */
12058 {
12064 /* Check if cand1->fn and cand2->fn are versions of the same function. It
12065 is possible that cand1->fn and cand2->fn are function versions but of
12066 different functions. Check types to see if they are versions of the same
12067 function. */
12070 {
12071 /* Always make the version with the higher priority, more
12072 specialized, win. */
12076 else
12078 }
12079 }
12081 /* If the two function declarations represent the same function (this can
12082 happen with declarations in multiple scopes and arg-dependent lookup),
12083 arbitrarily choose one. But first make sure the default args we're
12084 using match. */
12087 {
12094 {
12095 /* Don't crash if the fn is variadic. */
12100 }
12108 {
12111 {
12113 {
12115 {
12116 auto_diagnostic_group d;
12118 "default argument mismatch in "
12120 {
12125 }
12126 }
12127 else
12129 }
12130 else
12133 }
12136 }
12139 }
12141 tweak:
12143 /* Extension: If the worst conversion for one candidate is better than the
12144 worst conversion for the other, take the first. */
12146 {
12151 {
12156 }
12162 {
12163 /* Don't choose a deleted function over ambiguity. */
12167 {
12168 auto_diagnostic_group d;
12170 "ISO C++ says that these are ambiguous, even "
12171 "though the worst conversion for the first is "
12173 {
12176 }
12177 }
12178 else
12181 }
12182 }
12186 }
12188 /* Given a list of candidates for overloading, find the best one, if any.
12189 This algorithm has a worst case of O(2n) (winner is last), and a best
12190 case of O(n/2) (totally ambiguous); much better than a sorting
12191 algorithm. */
12195 {
12200 /* Walk through the list once, comparing each current champ to the next
12201 candidate, knocking out a candidate or two with each comparison. */
12204 {
12208 else
12209 {
12211 {
12216 }
12217 else
12218 {
12221 }
12224 }
12225 }
12227 /* Make sure the champ is better than all the candidates it hasn't yet
12228 been compared to. */
12231 challenger != champ
12234 {
12238 }
12241 }
12243 /* Returns nonzero if things of type FROM can be converted to TO. */
12245 bool
12247 {
12249 /* implicit_conversion only considers user-defined conversions
12250 if it has an expression for the call argument list. */
12254 }
12256 /* Returns nonzero if things of type FROM can be converted to TO with a
12257 standard conversion. */
12259 bool
12261 {
12263 }
12265 /* Returns nonzero if ARG (of type FROM) can be converted to TO. */
12267 bool
12269 tsubst_flags_t complain)
12270 {
12275 /* Get the high-water mark for the CONVERSION_OBSTACK. */
12277 /* We want to discard any access checks done for this test,
12278 as we might not be in the appropriate access context and
12279 we'll do the check again when we actually perform the
12280 conversion. */
12287 /* Discard the access checks now. */
12289 /* Free all the conversions we allocated. */
12293 }
12295 /* Like can_convert_arg, but allows dubious conversions as well. */
12297 bool
12299 tsubst_flags_t complain)
12300 {
12304 /* Get the high-water mark for the CONVERSION_OBSTACK. */
12306 /* Try to perform the conversion. */
12309 /* Free all the conversions we allocated. */
12313 }
12315 /* Convert EXPR to TYPE. Return the converted expression.
12317 Note that we allow bad conversions here because by the time we get to
12318 this point we are committed to doing the conversion. If we end up
12319 doing a bad conversion, convert_like will complain. */
12321 tree
12324 {
12331 else
12337 /* Get the high-water mark for the CONVERSION_OBSTACK. */
12345 {
12349 }
12351 {
12352 /* In a template, we are only concerned about determining the
12353 type of non-dependent expressions, so we do not have to
12354 perform the actual conversion. But for initializers, we
12355 need to be able to perform it at instantiation
12356 (or instantiate_non_dependent_expr) time. */
12362 }
12363 else
12366 /* Free all the conversions we allocated. */
12370 }
12372 tree
12374 {
12376 LOOKUP_IMPLICIT);
12377 }
12379 /* Convert EXPR to TYPE (as a direct-initialization) if that is
12380 permitted. If the conversion is valid, the converted expression is
12381 returned. Otherwise, NULL_TREE is returned, except in the case
12382 that TYPE is a class type; in that case, an error is issued. If
12383 C_CAST_P is true, then this direct-initialization is taking
12384 place as part of a static_cast being attempted as part of a C-style
12385 cast. */
12387 tree
12389 tree expr,
12391 tsubst_flags_t complain)
12392 {
12398 /* [dcl.init]
12400 If the destination type is a (possibly cv-qualified) class type:
12402 -- If the initialization is direct-initialization ...,
12403 constructors are considered.
12405 -- If overload resolution is successful, the selected constructor
12406 is called to initialize the object, with the initializer expression
12407 or expression-list as its argument(s).
12409 -- Otherwise, if no constructor is viable, the destination type is
12410 a (possibly cv-qualified) aggregate class A, and the initializer is
12411 a parenthesized expression-list, the object is initialized as
12412 follows... */
12414 {
12419 }
12421 /* Get the high-water mark for the CONVERSION_OBSTACK. */
12425 c_cast_p,
12430 {
12431 /* In a template, we are only concerned about determining the
12432 type of non-dependent expressions, so we do not have to
12433 perform the actual conversion. But for initializers, we
12434 need to be able to perform it at instantiation
12435 (or instantiate_non_dependent_expr) time. */
12438 }
12439 else
12444 /* Free all the conversions we allocated. */
12448 }
12450 /* When initializing a reference that lasts longer than a full-expression,
12451 this special rule applies:
12453 [class.temporary]
12455 The temporary to which the reference is bound or the temporary
12456 that is the complete object to which the reference is bound
12457 persists for the lifetime of the reference.
12459 The temporaries created during the evaluation of the expression
12460 initializing the reference, except the temporary to which the
12461 reference is bound, are destroyed at the end of the
12462 full-expression in which they are created.
12464 In that case, we store the converted expression into a new
12465 VAR_DECL in a new scope.
12467 However, we want to be careful not to create temporaries when
12468 they are not required. For example, given:
12470 struct B {};
12471 struct D : public B {};
12472 D f();
12473 const B& b = f();
12475 there is no need to copy the return value from "f"; we can just
12476 extend its lifetime. Similarly, given:
12478 struct S {};
12479 struct T { operator S(); };
12480 T t;
12481 const S& s = t;
12483 we can extend the lifetime of the return value of the conversion
12484 operator.
12486 The next several functions are involved in this lifetime extension. */
12488 /* DECL is a VAR_DECL or FIELD_DECL whose type is a REFERENCE_TYPE. The
12489 reference is being bound to a temporary. Create and return a new
12490 VAR_DECL with the indicated TYPE; this variable will store the value to
12491 which the reference is bound. */
12493 tree
12495 {
12498 /* Register the variable. */
12501 {
12502 /* Namespace-scope or local static; give it a mangled name. */
12504 /* If an initializer is visible to multiple translation units, those
12505 translation units must agree on the addresses of the
12506 temporaries. Therefore the temporaries must be given a consistent name
12507 and vague linkage. The mangled name of a temporary is the name of the
12508 non-temporary object in whose initializer they appear, prefixed with
12509 GR and suffixed with a sequence number mangled using the usual rules
12510 for a seq-id. Temporaries are numbered with a pre-order, depth-first,
12511 left-to-right walk of the complete initializer. */
12517 }
12518 else
12519 /* Create a new cleanup level if necessary. */
12523 }
12525 /* EXPR is the initializer for a variable DECL of reference or
12526 std::initializer_list type. Create, push and return a new VAR_DECL
12527 for the initializer so that it will live as long as DECL. Any
12528 cleanup for the new variable is returned through CLEANUP, and the
12529 code to initialize the new variable is returned through INITP. */
12531 static tree
12534 {
12535 tree init;
12536 tree type;
12537 tree var;
12539 /* Create the temporary variable. */
12543 /* If the rvalue is the result of a function call it will be
12544 a TARGET_EXPR. If it is some other construct (such as a
12545 member access expression where the underlying object is
12546 itself the result of a function call), turn it into a
12547 TARGET_EXPR here. It is important that EXPR be a
12548 TARGET_EXPR below since otherwise the INIT_EXPR will
12549 attempt to make a bitwise copy of EXPR to initialize
12550 VAR. */
12558 {
12562 }
12564 /* Recursively extend temps in this initializer. */
12567 cond_guard);
12569 /* Any reference temp has a non-trivial initializer. */
12572 /* If the initializer is constant, put it in DECL_INITIAL so we get
12573 static initialization and use in constant expressions. */
12575 /* As in store_init_value. */
12578 {
12580 {
12581 /* 5.19 says that a constant expression can include an
12582 lvalue-rvalue conversion applied to "a glvalue of literal type
12583 that refers to a non-volatile temporary object initialized
12584 with a constant expression". Rather than try to communicate
12585 that this VAR_DECL is a temporary, just mark it constexpr. */
12590 }
12593 }
12594 else
12595 /* Create the INIT_EXPR that will initialize the temporary
12596 variable. */
12599 {
12604 else
12605 {
12608 {
12610 {
12612 {
12617 boolean_false_node,
12618 tf_warning_or_error);
12620 }
12623 }
12625 }
12626 }
12628 /* We must be careful to destroy the temporary only
12629 after its initialization has taken place. If the
12630 initialization throws an exception, then the
12631 destructor should not be run. We cannot simply
12632 transform INIT into something like:
12634 (INIT, ({ CLEANUP_STMT; }))
12636 because emit_local_var always treats the
12637 initializer as a full-expression. Thus, the
12638 destructor would run too early; it would run at the
12639 end of initializing the reference variable, rather
12640 than at the end of the block enclosing the
12641 reference variable.
12643 The solution is to pass back a cleanup expression
12644 which the caller is responsible for attaching to
12645 the statement tree. */
12646 }
12647 else
12648 {
12651 {
12654 tls_aggregates);
12655 else
12657 static_aggregates);
12658 }
12659 else
12660 /* Check whether the dtor is callable. */
12662 }
12663 /* Avoid -Wunused-variable warning (c++/38958). */
12670 }
12672 /* Convert EXPR to the indicated reference TYPE, in a way suitable for
12673 initializing a variable of that TYPE. */
12675 tree
12678 {
12686 /* Get the high-water mark for the CONVERSION_OBSTACK. */
12691 /* If this conversion failed, we're in C++20, and we have something like
12692 A& a(b) where A is an aggregate, try again, this time as A& a{b}. */
12695 {
12701 /* If this worked, use it. */
12704 }
12706 {
12708 {
12717 else
12721 }
12723 }
12726 /* Perform the conversion. */
12729 /* We gave an error in build_user_type_conversion_1. */
12731 else
12734 /* Free all the conversions we allocated. */
12738 }
12740 /* If *P is an xvalue expression, prevent temporary lifetime extension if it
12741 gets used to initialize a reference. */
12743 static tree
12745 {
12751 /* Change a TARGET_EXPR from prvalue to xvalue. */
12756 }
12758 /* Subroutine of extend_ref_init_temps. Possibly extend one initializer,
12759 which is bound either to a reference or a std::initializer_list. */
12761 static tree
12764 {
12769 {
12772 cond_guard);
12774 }
12776 {
12783 {
12786 tf_warning_or_error);
12789 tf_warning_or_error);
12790 }
12797 {
12800 tf_warning_or_error);
12803 tf_warning_or_error);
12804 }
12806 }
12809 /* Deal with binding to a subobject. */
12814 {
12822 }
12824 }
12826 /* INIT is part of the initializer for DECL. If there are any
12827 reference or initializer lists being initialized, extend their
12828 lifetime to match that of DECL. */
12830 tree
12833 {
12839 else
12840 {
12845 {
12846 /* [dcl.init] When initializing an aggregate from a parenthesized list
12847 of values... a temporary object bound to a reference does not have
12848 its lifetime extended. */
12853 {
12854 /* The temporary array underlying a std::initializer_list
12855 is handled like a reference temporary. */
12858 cond_guard);
12860 }
12861 else
12862 {
12868 cond_guard);
12869 }
12873 }
12874 }
12877 }
12879 /* Returns true iff an initializer for TYPE could contain temporaries that
12880 need to be extended because they are bound to references or
12881 std::initializer_list. */
12883 bool
12885 {
12890 {
12897 }
12899 }
12901 /* Returns true iff TYPE is some variant of std::initializer_list. */
12903 bool
12905 {
12910 /* Look through typedefs. */
12915 }
12917 /* Returns true iff DECL is a list constructor: i.e. a constructor which
12918 will accept an argument list of a single std::initializer_list<T>. */
12920 bool
12922 {
12924 tree arg;
12936 /* There are more non-defaulted parms. */
12940 }