| blob | c822a70a017668b3aedff2dfa50eba3962bfa02b |
1 /* Functions related to invoking -*- C++ -*- methods and overloaded functions.
2 Copyright (C) 1987-2018 Free Software Foundation, Inc.
3 Contributed by Michael Tiemann (tiemann@cygnus.com) and
4 modified by Brendan Kehoe (brendan@cygnus.com).
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
11 any later version.
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
23 /* High-level class interface. */
45 /* The various kinds of conversion. */
48 ck_identity,
49 ck_lvalue,
50 ck_fnptr,
51 ck_qual,
52 ck_std,
53 ck_ptr,
54 ck_pmem,
55 ck_base,
56 ck_ref_bind,
57 ck_user,
58 ck_ambig,
59 ck_list,
60 ck_aggr,
61 ck_rvalue
62 };
64 /* The rank of the conversion. Order of the enumerals matters; better
65 conversions should come earlier in the list. */
68 cr_identity,
69 cr_exact,
70 cr_promotion,
71 cr_std,
72 cr_pbool,
73 cr_user,
74 cr_ellipsis,
75 cr_bad
76 };
78 /* An implicit conversion sequence, in the sense of [over.best.ics].
79 The first conversion to be performed is at the end of the chain.
80 That conversion is always a cr_identity conversion. */
83 /* The kind of conversion represented by this step. */
84 conversion_kind kind;
85 /* The rank of this conversion. */
86 conversion_rank rank;
90 /* True if this conversion would be permitted with a bending of
91 language standards, e.g. disregarding pointer qualifiers or
92 converting integers to pointers. */
94 /* If KIND is ck_ref_bind ck_base_conv, true to indicate that a
95 temporary should be created to hold the result of the
96 conversion. */
98 /* If KIND is ck_ptr or ck_pmem, true to indicate that a conversion
99 from a pointer-to-derived to pointer-to-base is being performed. */
101 /* If KIND is ck_ref_bind, true when either an lvalue reference is
102 being bound to an lvalue expression or an rvalue reference is
103 being bound to an rvalue expression. If KIND is ck_rvalue,
104 true when we are treating an lvalue as an rvalue (12.8p33). If
105 KIND is ck_base, always false. */
108 /* The type of the expression resulting from the conversion. */
109 tree type;
111 /* The next conversion in the chain. Since the conversions are
112 arranged from outermost to innermost, the NEXT conversion will
113 actually be performed before this conversion. This variant is
114 used only when KIND is neither ck_identity, ck_ambig nor
115 ck_list. Please use the next_conversion function instead
116 of using this field directly. */
118 /* The expression at the beginning of the conversion chain. This
119 variant is used only if KIND is ck_identity or ck_ambig. */
120 tree expr;
121 /* The array of conversions for an initializer_list, so this
122 variant is used only when KIN D is ck_list. */
125 /* The function candidate corresponding to this conversion
126 sequence. This field is only used if KIND is ck_user. */
128 };
130 #define CONVERSION_RANK(NODE) \
131 ((NODE)->bad_p ? cr_bad \
132 : (NODE)->ellipsis_p ? cr_ellipsis \
133 : (NODE)->user_conv_p ? cr_user \
134 : (NODE)->rank)
136 #define BAD_CONVERSION_RANK(NODE) \
137 ((NODE)->ellipsis_p ? cr_ellipsis \
138 : (NODE)->user_conv_p ? cr_user \
139 : (NODE)->rank)
148 tsubst_flags_t);
153 #define convert_like(CONV, EXPR, COMPLAIN) \
154 convert_like_real ((CONV), (EXPR), NULL_TREE, 0, \
157 #define convert_like_with_context(CONV, EXPR, FN, ARGNO, COMPLAIN ) \
158 convert_like_real ((CONV), (EXPR), (FN), (ARGNO), \
166 tsubst_flags_t);
178 static void add_builtin_candidates
181 static void add_builtin_candidate
185 static void build_builtin_candidate
195 tsubst_flags_t);
197 tsubst_flags_t);
217 tsubst_flags_t);
221 /* Returns nonzero iff the destructor name specified in NAME matches BASETYPE.
222 NAME can take many forms... */
224 bool
226 {
227 /* Just accept something we've already complained about. */
236 {
241 else
243 }
244 else
245 {
246 /* In the case of:
248 template <class T> struct S { ~S(); };
249 int i;
250 i.~S();
252 NAME will be a class template. */
255 }
260 }
262 /* We want the address of a function or method. We avoid creating a
263 pointer-to-member function. */
265 tree
267 {
270 /* We have to do these by hand to avoid real pointer to member
271 functions. */
273 {
275 {
279 complain);
280 }
282 }
283 else
287 }
289 /* Build a CALL_EXPR, we can handle FUNCTION_TYPEs, METHOD_TYPEs, or
290 POINTER_TYPE to those. Note, pointer to member function types
291 (TYPE_PTRMEMFUNC_P) must be handled by our callers. There are
292 two variants. build_call_a is the primitive taking an array of
293 arguments, while build_call_n is a wrapper that handles varargs. */
295 tree
297 {
300 else
301 {
311 }
312 }
314 /* Update various flags in cfun and the call itself based on what is being
315 called. Split out of build_call_a so that bot_manip can use it too. */
317 void
319 {
323 /* We check both the decl and the type; a function may be known not to
324 throw without being declared throw(). */
338 }
340 tree
342 {
343 tree decl;
344 tree result_type;
345 tree fntype;
355 /* An rvalue has no cv-qualifiers. */
366 {
367 /* We invoke build_call directly for several library
368 functions. These may have been declared normally if
369 we're building libgcc, so we can't just check
370 DECL_ARTIFICIAL. */
375 }
381 /* Don't pass empty class objects by value. This is useful
382 for tags in STL, which are used to control overload resolution.
383 We don't need to handle other cases of copying empty classes. */
386 {
390 {
394 }
395 }
398 }
400 /* New overloading code. */
407 };
409 /* Information for providing diagnostics about why overloading failed. */
412 rr_none,
413 rr_arity,
414 rr_explicit_conversion,
415 rr_template_conversion,
416 rr_arg_conversion,
417 rr_bad_arg_conversion,
418 rr_template_unification,
419 rr_invalid_copy,
420 rr_inherited_ctor,
421 rr_constraint_failure
422 };
425 /* The index of the argument, 0-based. */
427 /* The actual argument or its type. */
428 tree from;
429 /* The type of the parameter. */
430 tree to_type;
431 };
436 /* Information about an arity mismatch. */
438 /* The expected number of arguments. */
440 /* The actual number of arguments in the call. */
442 /* Whether the call was a varargs call. */
445 /* Information about an argument conversion mismatch. */
447 /* Same, but for bad argument conversions. */
449 /* Information about template unification failures. These are the
450 parameters passed to fn_type_unification. */
452 tree tmpl;
453 tree explicit_targs;
457 tree return_type;
458 unification_kind_t strict;
461 /* Information about template instantiation failures. These are the
462 parameters passed to instantiate_template. */
464 tree tmpl;
465 tree targs;
468 };
471 /* The FUNCTION_DECL that will be called if this candidate is
472 selected by overload resolution. */
473 tree fn;
474 /* If not NULL_TREE, the first argument to use when calling this
475 function. */
476 tree first_arg;
477 /* The rest of the arguments to use when calling this function. If
478 there are no further arguments this may be NULL or it may be an
479 empty vector. */
481 /* The implicit conversion sequences for each of the arguments to
482 FN. */
484 /* The number of implicit conversion sequences. */
486 /* If FN is a user-defined conversion, the standard conversion
487 sequence from the type returned by FN to the desired destination
488 type. */
491 /* If FN is a member function, the binfo indicating the path used to
492 qualify the name of FN at the call site. This path is used to
493 determine whether or not FN is accessible if it is selected by
494 overload resolution. The DECL_CONTEXT of FN will always be a
495 (possibly improper) base of this binfo. */
496 tree access_path;
497 /* If FN is a non-static member function, the binfo indicating the
498 subobject to which the `this' pointer should be converted if FN
499 is selected by overload resolution. The type pointed to by
500 the `this' pointer must correspond to the most derived class
501 indicated by the CONVERSION_PATH. */
502 tree conversion_path;
503 tree template_decl;
504 tree explicit_targs;
509 /* The flags active in add_candidate. */
511 };
513 /* Returns true iff T is a null pointer constant in the sense of
514 [conv.ptr]. */
516 bool
518 {
521 /* [conv.ptr]
523 A null pointer constant is an integral constant expression
524 (_expr.const_) rvalue of integer type that evaluates to zero or
525 an rvalue of type std::nullptr_t. */
530 {
533 /* Core issue 903 says only literal 0 is a null pointer constant. */
540 }
542 {
547 }
550 }
552 /* Returns true iff T is a null member pointer value (4.11). */
554 bool
556 {
565 else
567 }
569 /* Returns nonzero if PARMLIST consists of only default parms,
570 ellipsis, and/or undeduced parameter packs. */
572 bool
574 {
581 }
583 /* Allocate N bytes of memory from the conversion obstack. The memory
584 is zeroed before being returned. */
588 {
591 {
594 }
598 }
600 /* Allocate rejection reasons. */
604 {
609 }
613 {
619 }
623 {
630 }
634 {
641 }
645 {
651 }
655 {
661 }
668 {
675 /* Copy args to our own storage. */
683 }
687 {
689 }
693 {
696 }
700 {
703 }
705 // Build a constraint failure record, saving information into the
706 // template_instantiation field of the rejection. If FN is not a template
707 // declaration, the TMPL member is the FN declaration and TARGS is empty.
711 {
714 {
717 }
718 else
719 {
722 }
724 }
726 /* Dynamically allocate a conversion. */
730 {
735 }
737 /* Make sure that all memory on the conversion obstack has been
738 freed. */
740 void
742 {
746 }
748 /* Dynamically allocate an array of N conversions. */
752 {
754 }
758 {
762 /* Note that the caller is responsible for filling in t->cand for
763 user-defined conversions. */
769 {
786 }
792 }
794 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
795 specialization of std::initializer_list<T>, if such a conversion is
796 possible. */
800 {
806 tree val;
808 /* Within a list-initialization we can have more user-defined
809 conversions. */
811 /* But no narrowing conversions. */
814 /* Can't make an array of these types. */
821 {
822 conversion *sub
829 }
837 {
845 }
848 }
850 /* Return the next conversion of the conversion chain (if applicable),
851 or NULL otherwise. Please use this function instead of directly
852 accessing fields of struct conversion. */
856 {
863 }
865 /* Subroutine of build_aggr_conv: check whether CTOR, a braced-init-list,
866 is a valid aggregate initializer for array type ATYPE. */
868 static bool
870 {
874 {
880 else
882 complain);
885 }
887 }
889 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
890 aggregate class, if such a conversion is possible. */
894 {
900 /* We already called reshape_init in implicit_conversion. */
902 /* The conversions within the init-list aren't affected by the enclosing
903 context; they're always simple copy-initialization. */
907 {
909 tree val;
917 /* Value-initialization of reference is ill-formed. */
919 else
920 {
924 }
930 else
932 complain);
939 }
951 }
953 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, an
954 array type, if such a conversion is possible. */
958 {
963 tree val;
968 /* We might need to propagate the size from the element to the array. */
973 {
977 }
982 {
983 conversion *sub
995 }
1004 }
1006 /* Represent a conversion from CTOR, a braced-init-list, to TYPE, a
1007 complex type, if such a conversion is possible. */
1011 tsubst_flags_t complain)
1012 {
1017 tree val;
1028 {
1029 conversion *sub
1041 }
1050 }
1052 /* Build a representation of the identity conversion from EXPR to
1053 itself. The TYPE should match the type of EXPR, if EXPR is non-NULL. */
1057 {
1065 }
1067 /* Converting from EXPR to TYPE was ambiguous in the sense that there
1068 were multiple user-defined conversions to accomplish the job.
1069 Build a conversion that indicates that ambiguity. */
1073 {
1081 }
1083 tree
1085 {
1089 }
1091 /* Returns the standard conversion path (see [conv]) from type FROM to type
1092 TO, if any. For proper handling of null pointer constants, you must
1093 also pass the expression EXPR to convert from. If C_CAST_P is true,
1094 this conversion is coming from a C-style cast. */
1099 {
1103 tree qualified_to;
1107 {
1110 }
1116 {
1118 {
1124 }
1126 {
1127 /* Necessary for eg, TEMPLATE_ID_EXPRs (c++/50961). */
1130 }
1131 }
1138 {
1142 }
1143 /* Wrapping a ck_rvalue around a class prvalue (as a result of using
1144 obvalue_p) seems odd, since it's already a prvalue, but that's how we
1145 express the copy constructor call required by copy-initialization. */
1147 {
1149 {
1150 tree bitfield_type;
1153 {
1156 }
1157 }
1160 /* Tell convert_like_real to set LOOKUP_PREFER_RVALUE. */
1162 }
1164 /* Allow conversion between `__complex__' data types. */
1166 {
1167 /* The standard conversion sequence to convert FROM to TO is
1168 the standard conversion sequence to perform componentwise
1169 conversion. */
1172 complain);
1175 {
1178 }
1179 else
1183 }
1186 {
1190 }
1192 /* [conv.ptr]
1193 A null pointer constant can be converted to a pointer type; ... A
1194 null pointer constant of integral type can be converted to an
1195 rvalue of type std::nullptr_t. */
1203 {
1204 /* For backwards brain damage compatibility, allow interconversion of
1205 pointers and integers with a pedwarn. */
1208 }
1210 {
1211 /* For backwards brain damage compatibility, allow interconversion of
1212 enums and integers with a pedwarn. */
1215 }
1218 {
1219 tree to_pointee;
1220 tree from_pointee;
1223 {
1227 /* Since this is the target of a pointer, it can't have function
1228 qualifiers, so any TYPE_QUALS must be for attributes const or
1229 noreturn. Strip them. */
1236 }
1237 else
1238 {
1241 }
1245 to_pointee))
1246 ;
1250 {
1252 /* Don't try to apply restrict to void. */
1257 }
1259 {
1266 && (same_type_ignoring_top_level_qualifiers_p
1268 {
1271 }
1272 else
1274 }
1277 /* [conv.ptr]
1279 An rvalue of type "pointer to cv D," where D is a
1280 class type, can be converted to an rvalue of type
1281 "pointer to cv B," where B is a base class (clause
1282 _class.derived_) of D. If B is an inaccessible
1283 (clause _class.access_) or ambiguous
1284 (_class.member.lookup_) base class of D, a program
1285 that necessitates this conversion is ill-formed.
1286 Therefore, we use DERIVED_FROM_P, and do not check
1287 access or uniqueness. */
1289 {
1290 from_pointee
1296 }
1301 /* In a C-style cast, we ignore CV-qualification because we
1302 are allowed to perform a static_cast followed by a
1303 const_cast. */
1308 /* converting from string constant to char *. */
1312 /* Allow conversions among compatible ObjC pointer types (base
1313 conversions have been already handled above). */
1318 {
1321 }
1322 else
1326 }
1328 {
1342 else
1346 {
1348 tbase,
1354 }
1357 }
1359 {
1360 /* [conv.bool]
1362 A prvalue of arithmetic, unscoped enumeration, pointer, or pointer
1363 to member type can be converted to a prvalue of type bool. ...
1364 For direct-initialization (8.5 [dcl.init]), a prvalue of type
1365 std::nullptr_t can be converted to a prvalue of type bool; */
1371 {
1382 }
1385 }
1386 /* We don't check for ENUMERAL_TYPE here because there are no standard
1387 conversions to enum type. */
1388 /* As an extension, allow conversion to complex type. */
1390 {
1397 /* Give this a better rank if it's a promotion. */
1401 }
1407 {
1411 /* The derived-to-base conversion indicates the initialization
1412 of a parameter with base type from an object of a derived
1413 type. A temporary object is created to hold the result of
1414 the conversion unless we're binding directly to a reference. */
1416 }
1417 else
1424 }
1426 /* Returns nonzero if T1 is reference-related to T2. */
1428 bool
1430 {
1437 /* [dcl.init.ref]
1439 Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
1440 to "cv2 T2" if T1 is the same type as T2, or T1 is a base class
1441 of T2. */
1445 }
1447 /* Returns nonzero if T1 is reference-compatible with T2. */
1449 static bool
1451 {
1452 /* [dcl.init.ref]
1454 "cv1 T1" is reference compatible with "cv2 T2" if
1455 * T1 is reference-related to T2 or
1456 * T2 is "noexcept function" and T1 is "function", where the
1457 function types are otherwise the same,
1458 and cv1 is the same cv-qualification as, or greater cv-qualification
1459 than, cv2. */
1463 }
1465 /* A reference of the indicated TYPE is being bound directly to the
1466 expression represented by the implicit conversion sequence CONV.
1467 Return a conversion sequence for this binding. */
1471 {
1472 tree t;
1479 /* [over.ics.rank]
1481 When a parameter of reference type binds directly
1482 (_dcl.init.ref_) to an argument expression, the implicit
1483 conversion sequence is the identity conversion, unless the
1484 argument expression has a type that is a derived class of the
1485 parameter type, in which case the implicit conversion sequence is
1486 a derived-to-base Conversion.
1488 If the parameter binds directly to the result of applying a
1489 conversion function to the argument expression, the implicit
1490 conversion sequence is a user-defined conversion sequence
1491 (_over.ics.user_), with the second standard conversion sequence
1492 either an identity conversion or, if the conversion function
1493 returns an entity of a type that is a derived class of the
1494 parameter type, a derived-to-base conversion. */
1496 {
1497 /* Represent the derived-to-base conversion. */
1499 /* We will actually be binding to the base-class subobject in
1500 the derived class, so we mark this conversion appropriately.
1501 That way, convert_like knows not to generate a temporary. */
1503 }
1505 }
1507 /* Returns the conversion path from type FROM to reference type TO for
1508 purposes of reference binding. For lvalue binding, either pass a
1509 reference type to FROM or an lvalue expression to EXPR. If the
1510 reference will be bound to a temporary, NEED_TEMPORARY_P is set for
1511 the conversion returned. If C_CAST_P is true, this
1512 conversion is coming from a C-style cast. */
1516 tsubst_flags_t complain)
1517 {
1521 tree tfrom;
1524 cp_lvalue_kind gl_kind;
1528 {
1533 }
1536 {
1538 /* DR 1288: Otherwise, if the initializer list has a single element
1539 of type E and ... [T's] referenced type is reference-related to E,
1540 the object or reference is initialized from that element... */
1542 {
1548 {
1552 }
1553 }
1554 /* Otherwise, if T is a reference type, a prvalue temporary of the
1555 type referenced by T is copy-list-initialized or
1556 direct-list-initialized, depending on the kind of initialization
1557 for the reference, and the reference is bound to that temporary. */
1560 skip:;
1561 }
1564 {
1569 else
1571 }
1577 else
1580 /* Don't allow a class prvalue when LOOKUP_NO_TEMP_BIND. */
1585 /* Same mask as real_lvalue_p. */
1592 /* Figure out whether or not the types are reference-related and
1593 reference compatible. We have to do this after stripping
1594 references from FROM. */
1596 /* If this is a C cast, first convert to an appropriately qualified
1597 type, so that we can later do a const_cast to the desired type. */
1603 /* Directly bind reference when target expression's type is compatible with
1604 the reference and expression is an lvalue. In DR391, the wording in
1605 [8.5.3/5 dcl.init.ref] is changed to also require direct bindings for
1606 const and rvalue references to rvalues of compatible class type.
1607 We should also do direct bindings for non-class xvalues. */
1609 {
1610 /* [dcl.init.ref]
1612 If the initializer expression
1614 -- is an lvalue (but not an lvalue for a bit-field), and "cv1 T1"
1615 is reference-compatible with "cv2 T2,"
1617 the reference is bound directly to the initializer expression
1618 lvalue.
1620 [...]
1621 If the initializer expression is an rvalue, with T2 a class type,
1622 and "cv1 T1" is reference-compatible with "cv2 T2", the reference
1623 is bound to the object represented by the rvalue or to a sub-object
1624 within that object. */
1630 /* Handle rvalue reference to function properly. */
1631 conv->rvaluedness_matches_p
1633 else
1634 conv->rvaluedness_matches_p
1639 /* For the purposes of overload resolution, we ignore the fact
1640 this expression is a bitfield or packed field. (In particular,
1641 [over.ics.ref] says specifically that a function with a
1642 non-const reference parameter is viable even if the
1643 argument is a bitfield.)
1645 However, when we actually call the function we must create
1646 a temporary to which to bind the reference. If the
1647 reference is volatile, or isn't const, then we cannot make
1648 a temporary, so we just issue an error when the conversion
1649 actually occurs. */
1652 /* Don't allow binding of lvalues (other than function lvalues) to
1653 rvalue references. */
1658 /* Nor the reverse. */
1669 }
1670 /* [class.conv.fct] A conversion function is never used to convert a
1671 (possibly cv-qualified) object to the (possibly cv-qualified) same
1672 object type (or a reference to it), to a (possibly cv-qualified) base
1673 class of that type (or a reference to it).... */
1676 {
1677 /* [dcl.init.ref]
1679 If the initializer expression
1681 -- has a class type (i.e., T2 is a class type) can be
1682 implicitly converted to an lvalue of type "cv3 T3," where
1683 "cv1 T1" is reference-compatible with "cv3 T3". (this
1684 conversion is selected by enumerating the applicable
1685 conversion functions (_over.match.ref_) and choosing the
1686 best one through overload resolution. (_over.match_).
1688 the reference is bound to the lvalue result of the conversion
1689 in the second case. */
1691 complain);
1694 }
1696 /* From this point on, we conceptually need temporaries, even if we
1697 elide them. Only the cases above are "direct bindings". */
1701 /* [over.ics.rank]
1703 When a parameter of reference type is not bound directly to an
1704 argument expression, the conversion sequence is the one required
1705 to convert the argument expression to the underlying type of the
1706 reference according to _over.best.ics_. Conceptually, this
1707 conversion sequence corresponds to copy-initializing a temporary
1708 of the underlying type with the argument expression. Any
1709 difference in top-level cv-qualification is subsumed by the
1710 initialization itself and does not constitute a conversion. */
1712 /* [dcl.init.ref]
1714 Otherwise, the reference shall be an lvalue reference to a
1715 non-volatile const type, or the reference shall be an rvalue
1716 reference.
1718 We try below to treat this as a bad conversion to improve diagnostics,
1719 but if TO is an incomplete class, we need to reject this conversion
1720 now to avoid unnecessary instantiation. */
1725 /* We're generating a temporary now, but don't bind any more in the
1726 conversion (specifically, don't slice the temporary returned by a
1727 conversion operator). */
1730 /* Core issue 899: When [copy-]initializing a temporary to be bound
1731 to the first parameter of a copy constructor (12.8) called with
1732 a single argument in the context of direct-initialization,
1733 explicit conversion functions are also considered.
1735 So don't set LOOKUP_ONLYCONVERTING in that case. */
1746 {
1747 /* If initializing the temporary used a conversion function,
1748 recalculate the second conversion sequence. */
1752 {
1755 conversion *new_second
1761 }
1762 }
1765 /* This reference binding, unlike those above, requires the
1766 creation of a temporary. */
1770 /* [dcl.init.ref]
1772 Otherwise, the reference shall be an lvalue reference to a
1773 non-volatile const type, or the reference shall be an rvalue
1774 reference. */
1778 /* [dcl.init.ref]
1780 Otherwise, a temporary of type "cv1 T1" is created and
1781 initialized from the initializer expression using the rules for a
1782 non-reference copy initialization. If T1 is reference-related to
1783 T2, cv1 must be the same cv-qualification as, or greater
1784 cv-qualification than, cv2; otherwise, the program is ill-formed. */
1789 }
1791 /* Returns the implicit conversion sequence (see [over.ics]) from type
1792 FROM to type TO. The optional expression EXPR may affect the
1793 conversion. FLAGS are the usual overloading flags. If C_CAST_P is
1794 true, this conversion is coming from a C-style cast. */
1799 {
1806 /* Other flags only apply to the primary function in overload
1807 resolution, or after we've chosen one. */
1812 /* FIXME: actually we don't want warnings either, but we can't just
1813 have 'complain &= ~(tf_warning|tf_error)' because it would cause
1814 the regression of, eg, g++.old-deja/g++.benjamin/16077.C.
1815 We really ought not to issue that warning until we've committed
1816 to that conversion. */
1819 /* Call reshape_init early to remove redundant braces. */
1824 {
1829 }
1833 else
1840 {
1844 /* As an extension, allow list-initialization of _Complex. */
1846 {
1850 }
1852 /* Allow conversion from an initializer-list with one element to a
1853 scalar type. */
1855 {
1857 tree elt;
1863 else
1869 {
1872 /* Too many levels of braces, i.e. '{{1}}'. */
1875 }
1876 }
1879 }
1885 {
1895 {
1899 {
1900 /* "If C is not an initializer-list constructor and the
1901 initializer list has a single element of type cv U, where U is
1902 X or a class derived from X, the implicit conversion sequence
1903 has Exact Match rank if U is X, or Conversion rank if U is
1904 derived from X." */
1910 }
1912 }
1914 /* We used to try to bind a reference to a temporary here, but that
1915 is now handled after the recursive call to this function at the end
1916 of reference_binding. */
1918 }
1921 }
1923 /* Add a new entry to the list of candidates. Used by the add_*_candidate
1924 functions. ARGS will not be changed until a single candidate is
1925 selected. */
1934 {
1952 }
1954 /* Return the number of remaining arguments in the parameter list
1955 beginning with ARG. */
1957 int
1959 {
1964 n++;
1967 }
1969 /* Create an overload candidate for the function or method FN called
1970 with the argument list FIRST_ARG/ARGS and add it to CANDIDATES.
1971 FLAGS is passed on to implicit_conversion.
1973 This does not change ARGS.
1975 CTYPE, if non-NULL, is the type we want to pretend this function
1976 comes from for purposes of overload resolution. */
1983 tsubst_flags_t complain)
1984 {
1988 tree parmnode;
1994 /* At this point we should not see any functions which haven't been
1995 explicitly declared, except for friend functions which will have
1996 been found using argument dependent lookup. */
1999 /* The `this', `in_chrg' and VTT arguments to constructors are not
2000 considered in overload resolution. */
2002 {
2004 /* Bring back parameters omitted from an inherited ctor. */
2006 else
2010 {
2013 }
2014 }
2015 else
2021 /* 13.3.2 - Viable functions [over.match.viable]
2022 First, to be a viable function, a candidate function shall have enough
2023 parameters to agree in number with the arguments in the list.
2025 We need to check this first; otherwise, checking the ICSes might cause
2026 us to produce an ill-formed template instantiation. */
2030 {
2034 }
2038 {
2042 }
2044 /* An inherited constructor (12.6.3 [class.inhctor.init]) that has a first
2045 parameter of type "reference to cv C" (including such a constructor
2046 instantiated from a template) is excluded from the set of candidate
2047 functions when used to construct an object of type D with an argument list
2048 containing a single argument if C is reference-related to D. */
2050 && flag_new_inheriting_ctors
2052 {
2058 {
2061 }
2062 }
2064 /* Second, for a function to be viable, its constraints must be
2065 satisfied. */
2068 {
2071 }
2073 /* When looking for a function from a subobject from an implicit
2074 copy/move constructor/operator=, don't consider anything that takes (a
2075 reference to) an unrelated type. See c++/44909 and core 1092. */
2077 {
2083 else
2086 {
2089 ctype))
2091 }
2093 /* This only applies at the top level. */
2095 }
2100 /* Third, for F to be a viable function, there shall exist for each
2101 argument an implicit conversion sequence that converts that argument
2102 to the corresponding parameter of F. */
2107 {
2109 tree arg;
2118 else
2127 {
2133 /* The type of the implicit object parameter ('this') for
2134 overload resolution is not always the same as for the
2135 function itself; conversion functions are considered to
2136 be members of the class being converted, and functions
2137 introduced by a using-declaration are considered to be
2138 members of the class that uses them.
2140 Since build_over_call ignores the ICS for the `this'
2141 parameter, we can just change the parm type. */
2143 {
2144 parmtype = cp_build_qualified_type
2147 {
2148 /* If the function has a ref-qualifier, the implicit
2149 object parameter has reference type. */
2152 /* The special handling of 'this' conversions in compare_ics
2153 does not apply if there is a ref-qualifier. */
2155 }
2156 else
2157 {
2159 /* We don't use build_this here because we don't want to
2160 capture the object argument until we've chosen a
2161 non-static member function. */
2164 }
2165 }
2167 /* Core issue 899: When [copy-]initializing a temporary to be bound
2168 to the first parameter of a copy constructor (12.8) called with
2169 a single argument in the context of direct-initialization,
2170 explicit conversion functions are also considered.
2172 So set LOOKUP_COPY_PARM to let reference_binding know that
2173 it's being called in that context. We generalize the above
2174 to handle move constructors and template constructors as well;
2175 the standardese should soon be updated similarly. */
2179 && (same_type_ignoring_top_level_qualifiers_p
2181 {
2184 /* We allow user-defined conversions within init-lists, but
2185 don't list-initialize the copy parm, as that would mean
2186 using two levels of braces for the same type. */
2190 }
2191 else
2197 }
2198 else
2199 {
2203 }
2210 {
2214 }
2217 {
2220 }
2221 }
2223 out:
2226 }
2228 /* Create an overload candidate for the conversion function FN which will
2229 be invoked for expression OBJ, producing a pointer-to-function which
2230 will in turn be called with the argument list FIRST_ARG/ARGLIST,
2231 and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
2232 passed on to implicit_conversion.
2234 Actually, we don't really care about FN; we care about the type it
2235 converts to. There may be multiple conversion functions that will
2236 convert to that type, and we rely on build_user_type_conversion_1 to
2237 choose the best one; so when we create our candidate, we record the type
2238 instead of the function. */
2244 tsubst_flags_t complain)
2245 {
2263 /* Don't bother looking up the same type twice. */
2268 {
2274 else
2279 {
2282 /* Leave the 'cand' field null; we'll figure out the conversion in
2283 convert_like_real if this candidate is chosen. */
2285 }
2289 {
2293 }
2294 else
2295 {
2299 }
2306 {
2309 }
2316 }
2320 {
2324 }
2328 }
2330 static void
2334 {
2348 /* TRUTH_*_EXPR do "contextual conversion to bool", which means explicit
2349 conversion ops are allowed. We handle that here by just checking for
2350 boolean_type_node because other operators don't ask for it. COND_EXPR
2351 also does contextual conversion to bool for the first operand, but we
2352 handle that in build_conditional_expr, and type1 here is operand 2. */
2357 {
2364 {
2366 /* We need something for printing the candidate. */
2370 }
2372 {
2376 }
2378 }
2380 /* For COND_EXPR we rearranged the arguments; undo that now. */
2382 {
2387 complain);
2390 else
2391 {
2394 boolean_type_node);
2395 }
2396 }
2403 }
2405 static bool
2407 {
2409 }
2411 /* Returns nonzero if TYPE is a promoted arithmetic type. */
2413 static bool
2415 {
2416 /* [over.built]
2418 In this section, the term promoted integral type is used to refer
2419 to those integral types which are preserved by integral promotion
2420 (including e.g. int and long but excluding e.g. char).
2421 Similarly, the term promoted arithmetic type refers to promoted
2422 integral types plus floating types. */
2426 }
2428 /* Create any builtin operator overload candidates for the operator in
2429 question given the converted operand types TYPE1 and TYPE2. The other
2430 args are passed through from add_builtin_candidates to
2431 build_builtin_candidate.
2433 TYPE1 and TYPE2 may not be permissible, and we must filter them.
2434 If CODE is requires candidates operands of the same type of the kind
2435 of which TYPE1 and TYPE2 are, we add both candidates
2436 CODE (TYPE1, TYPE1) and CODE (TYPE2, TYPE2). */
2438 static void
2442 tsubst_flags_t complain)
2443 {
2445 {
2453 }
2456 {
2458 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2459 and VQ is either volatile or empty, there exist candidate operator
2460 functions of the form
2461 VQ T& operator++(VQ T&);
2462 T operator++(VQ T&, int);
2463 5 For every pair T, VQ), where T is an enumeration type or an arithmetic
2464 type other than bool, and VQ is either volatile or empty, there exist
2465 candidate operator functions of the form
2466 VQ T& operator--(VQ T&);
2467 T operator--(VQ T&, int);
2468 6 For every pair T, VQ), where T is a cv-qualified or cv-unqualified
2469 complete object type, and VQ is either volatile or empty, there exist
2470 candidate operator functions of the form
2471 T*VQ& operator++(T*VQ&);
2472 T*VQ& operator--(T*VQ&);
2473 T* operator++(T*VQ&, int);
2474 T* operator--(T*VQ&, int); */
2480 /* FALLTHRU */
2484 {
2487 }
2490 /* 7 For every cv-qualified or cv-unqualified object type T, there
2491 exist candidate operator functions of the form
2493 T& operator*(T*);
2495 8 For every function type T, there exist candidate operator functions of
2496 the form
2497 T& operator*(T*); */
2506 /* 9 For every type T, there exist candidate operator functions of the form
2507 T* operator+(T*);
2509 10For every promoted arithmetic type T, there exist candidate operator
2510 functions of the form
2511 T operator+(T);
2512 T operator-(T); */
2517 /* FALLTHRU */
2523 /* 11For every promoted integral type T, there exist candidate operator
2524 functions of the form
2525 T operator~(T); */
2532 /* 12For every quintuple C1, C2, T, CV1, CV2), where C2 is a class type, C1
2533 is the same type as C2 or is a derived class of C2, T is a complete
2534 object type or a function type, and CV1 and CV2 are cv-qualifier-seqs,
2535 there exist candidate operator functions of the form
2536 CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
2537 where CV12 is the union of CV1 and CV2. */
2541 {
2549 }
2552 /* 13For every pair of promoted arithmetic types L and R, there exist can-
2553 didate operator functions of the form
2554 LR operator*(L, R);
2555 LR operator/(L, R);
2556 LR operator+(L, R);
2557 LR operator-(L, R);
2558 bool operator<(L, R);
2559 bool operator>(L, R);
2560 bool operator<=(L, R);
2561 bool operator>=(L, R);
2562 bool operator==(L, R);
2563 bool operator!=(L, R);
2564 where LR is the result of the usual arithmetic conversions between
2565 types L and R.
2567 14For every pair of types T and I, where T is a cv-qualified or cv-
2568 unqualified complete object type and I is a promoted integral type,
2569 there exist candidate operator functions of the form
2570 T* operator+(T*, I);
2571 T& operator[](T*, I);
2572 T* operator-(T*, I);
2573 T* operator+(I, T*);
2574 T& operator[](I, T*);
2576 15For every T, where T is a pointer to complete object type, there exist
2577 candidate operator functions of the form112)
2578 ptrdiff_t operator-(T, T);
2580 16For every pointer or enumeration type T, there exist candidate operator
2581 functions of the form
2582 bool operator<(T, T);
2583 bool operator>(T, T);
2584 bool operator<=(T, T);
2585 bool operator>=(T, T);
2586 bool operator==(T, T);
2587 bool operator!=(T, T);
2589 17For every pointer to member type T, there exist candidate operator
2590 functions of the form
2591 bool operator==(T, T);
2592 bool operator!=(T, T); */
2599 {
2602 }
2603 /* FALLTHRU */
2616 {
2619 }
2621 {
2624 }
2625 /* Fall through. */
2641 {
2644 }
2647 {
2650 }
2656 /* FALLTHRU */
2659 {
2662 }
2664 {
2667 }
2670 /* 18For every pair of promoted integral types L and R, there exist candi-
2671 date operator functions of the form
2672 LR operator%(L, R);
2673 LR operator&(L, R);
2674 LR operator^(L, R);
2675 LR operator|(L, R);
2676 L operator<<(L, R);
2677 L operator>>(L, R);
2678 where LR is the result of the usual arithmetic conversions between
2679 types L and R. */
2687 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2691 /* 19For every triple L, VQ, R), where L is an arithmetic or enumeration
2692 type, VQ is either volatile or empty, and R is a promoted arithmetic
2693 type, there exist candidate operator functions of the form
2694 VQ L& operator=(VQ L&, R);
2695 VQ L& operator*=(VQ L&, R);
2696 VQ L& operator/=(VQ L&, R);
2697 VQ L& operator+=(VQ L&, R);
2698 VQ L& operator-=(VQ L&, R);
2700 20For every pair T, VQ), where T is any type and VQ is either volatile
2701 or empty, there exist candidate operator functions of the form
2702 T*VQ& operator=(T*VQ&, T*);
2704 21For every pair T, VQ), where T is a pointer to member type and VQ is
2705 either volatile or empty, there exist candidate operator functions of
2706 the form
2707 VQ T& operator=(VQ T&, T);
2709 22For every triple T, VQ, I), where T is a cv-qualified or cv-
2710 unqualified complete object type, VQ is either volatile or empty, and
2711 I is a promoted integral type, there exist candidate operator func-
2712 tions of the form
2713 T*VQ& operator+=(T*VQ&, I);
2714 T*VQ& operator-=(T*VQ&, I);
2716 23For every triple L, VQ, R), where L is an integral or enumeration
2717 type, VQ is either volatile or empty, and R is a promoted integral
2718 type, there exist candidate operator functions of the form
2720 VQ L& operator%=(VQ L&, R);
2721 VQ L& operator<<=(VQ L&, R);
2722 VQ L& operator>>=(VQ L&, R);
2723 VQ L& operator&=(VQ L&, R);
2724 VQ L& operator^=(VQ L&, R);
2725 VQ L& operator|=(VQ L&, R); */
2729 {
2733 {
2736 }
2737 /* FALLTHRU */
2750 if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type1) && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type2))
2763 {
2766 }
2771 }
2776 /* [over.built]
2778 For every pair of promoted arithmetic types L and R, there
2779 exist candidate operator functions of the form
2781 LR operator?(bool, L, R);
2783 where LR is the result of the usual arithmetic conversions
2784 between types L and R.
2786 For every type T, where T is a pointer or pointer-to-member
2787 type, there exist candidate operator functions of the form T
2788 operator?(bool, T, T); */
2792 /* That's OK. */
2795 /* Otherwise, the types should be pointers. */
2799 /* We don't check that the two types are the same; the logic
2800 below will actually create two candidates; one in which both
2801 parameter types are TYPE1, and one in which both parameter
2802 types are TYPE2. */
2813 }
2815 /* Make sure we don't create builtin candidates with dependent types. */
2819 {
2820 /* Try to recover if one of the types is non-dependent. But if
2821 there's only one type, there's nothing we can do. */
2824 /* And we lose if both are dependent. */
2827 /* Or if they have different forms. */
2835 }
2837 /* If we're dealing with two pointer types or two enumeral types,
2838 we need candidates for both of them. */
2847 {
2849 {
2851 error_mark_node,
2852 error_mark_node,
2853 CPO_CONVERSION,
2854 tf_none);
2856 {
2857 build_builtin_candidate
2861 }
2862 }
2864 build_builtin_candidate
2866 build_builtin_candidate
2869 }
2871 build_builtin_candidate
2873 }
2875 tree
2877 {
2883 }
2885 /* There are three conditions of builtin candidates:
2887 1) bool-taking candidates. These are the same regardless of the input.
2888 2) pointer-pair taking candidates. These are generated for each type
2889 one of the input types converts to.
2890 3) arithmetic candidates. According to the standard, we should generate
2891 all of these, but I'm trying not to...
2893 Here we generate a superset of the possible candidates for this particular
2894 case. That is a subset of the full set the standard defines, plus some
2895 other cases which the standard disallows. add_builtin_candidate will
2896 filter out the invalid set. */
2898 static void
2902 {
2906 /* TYPES[i] is the set of possible builtin-operator parameter types
2907 we will consider for the Ith argument. */
2912 {
2915 else
2917 }
2920 {
2921 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2922 and VQ is either volatile or empty, there exist candidate operator
2923 functions of the form
2924 VQ T& operator++(VQ T&); */
2934 /* 24There also exist candidate operator functions of the form
2935 bool operator!(bool);
2936 bool operator&&(bool, bool);
2937 bool operator||(bool, bool); */
2940 build_builtin_candidate
2947 build_builtin_candidate
2965 /* Fall through. */
2969 }
2975 {
2977 ;
2979 {
2980 tree convs;
2988 {
2993 }
2999 {
3012 {
3018 }
3022 }
3023 }
3024 else
3025 {
3030 {
3036 }
3038 }
3039 }
3041 /* Run through the possible parameter types of both arguments,
3042 creating candidates with those parameter types. */
3044 {
3046 tree u;
3050 add_builtin_candidate
3053 else
3054 add_builtin_candidate
3057 }
3061 }
3064 /* If TMPL can be successfully instantiated as indicated by
3065 EXPLICIT_TARGS and ARGLIST, adds the instantiation to CANDIDATES.
3067 TMPL is the template. EXPLICIT_TARGS are any explicit template
3068 arguments. ARGLIST is the arguments provided at the call-site.
3069 This does not change ARGLIST. The RETURN_TYPE is the desired type
3070 for conversion operators. If OBJ is NULL_TREE, FLAGS and CTYPE are
3071 as for add_function_candidate. If an OBJ is supplied, FLAGS and
3072 CTYPE are ignored, and OBJ is as for add_conv_candidate. */
3080 tsubst_flags_t complain)
3081 {
3091 tree arg;
3093 tree fn;
3097 /* We don't do deduction on the in-charge parameter, the VTT
3098 parameter or 'this'. */
3100 {
3104 /* We're deducing for a call to the result of a template conversion
3106 else
3108 }
3113 {
3116 else
3118 }
3126 {
3127 /* 12.8/6 says, "A declaration of a constructor for a class X is
3128 ill-formed if its first parameter is of type (optionally cv-qualified)
3129 X and either there are no other parameters or else all other
3130 parameters have default arguments. A member function template is never
3131 instantiated to produce such a constructor signature."
3133 So if we're trying to copy an object of the containing class, don't
3134 consider a template constructor that has a first parameter type that
3135 is just a template parameter, as we would deduce a signature that we
3136 would then reject in the code below. */
3138 {
3143 {
3147 }
3148 }
3149 }
3156 {
3159 }
3163 {
3166 }
3171 args_without_in_chrg,
3172 nargs_without_in_chrg,
3177 {
3178 /* Don't repeat unification later if it already resulted in errors. */
3182 nargs_without_in_chrg,
3184 else
3187 }
3190 {
3193 ctype))
3194 {
3195 /* We're trying to produce a constructor with a prohibited signature,
3196 as discussed above; handle here any cases we didn't catch then,
3197 such as X(X<T>). */
3200 }
3201 }
3204 /* Aha, this is a conversion function. */
3207 else
3212 /* This situation can occur if a member template of a template
3213 class is specialized. Then, instantiate_template might return
3214 an instantiation of the specialization, in which case the
3215 DECL_TI_TEMPLATE field will point at the original
3216 specialization. For example:
3218 template <class T> struct S { template <class U> void f(U);
3219 template <> void f(int) {}; };
3220 S<double> sd;
3221 sd.f(3);
3223 Here, TMPL will be template <class U> S<double>::f(U).
3224 And, instantiate template will give us the specialization
3225 template <> S<double>::f(int). But, the DECL_TI_TEMPLATE field
3226 for this will point at template <class T> template <> S<T>::f(int),
3227 so that we can find the definition. For the purposes of
3228 overload resolution, however, we want the original TMPL. */
3230 else
3235 fail:
3238 }
3247 {
3248 return
3253 }
3255 /* Create an overload candidate for the conversion function template TMPL,
3256 returning RETURN_TYPE, which will be invoked for expression OBJ to produce a
3257 pointer-to-function which will in turn be called with the argument list
3258 ARGLIST, and add it to CANDIDATES. This does not change ARGLIST. FLAGS is
3259 passed on to implicit_conversion. */
3263 tree obj,
3267 {
3268 /* Making this work broke PR 71117, so until the committee resolves core
3269 issue 2189, let's disable this candidate if there are any viable call
3270 operators. */
3274 return
3278 complain);
3279 }
3281 /* The CANDS are the set of candidates that were considered for
3282 overload resolution. Return the set of viable candidates, or CANDS
3283 if none are viable. If any of the candidates were viable, set
3284 *ANY_VIABLE_P to true. STRICT_P is true if a candidate should be
3285 considered viable only if it is strictly viable. */
3291 {
3297 /* Be strict inside templates, since build_over_call won't actually
3298 do the conversions to get pedwarns. */
3308 {
3312 {
3313 /* Be strict in the presence of a viable candidate. Also if
3314 there are template candidates, so that we get deduction errors
3315 for them instead of silently preferring a bad conversion. */
3318 {
3319 /* Put any spliced near matches back onto the main list so
3320 that we see them if there is no strict match. */
3326 }
3327 }
3330 {
3338 }
3339 else
3341 }
3344 }
3346 static bool
3348 {
3353 }
3355 /* OBJ is being used in an expression like "OBJ.f (...)". In other
3356 words, it is about to become the "this" pointer for a member
3357 function call. Take the address of the object. */
3359 static tree
3361 {
3362 /* In a template, we are only concerned about the type of the
3363 expression, so we can take a shortcut. */
3368 }
3370 /* Returns true iff functions are equivalent. Equivalent functions are
3371 not '==' only if one is a function-local extern function or if
3372 both are extern "C". */
3376 {
3385 }
3387 /* Print information about a candidate being rejected due to INFO. */
3389 static void
3391 {
3396 {
3397 /* Conversion of implicit `this' argument failed. */
3399 /* A bad conversion for 'this' must be discarding cv-quals. */
3402 from);
3403 else
3407 }
3409 {
3414 tf_warning_or_error);
3415 }
3417 /* Conversion of conversion function return value failed. */
3420 else
3423 }
3425 /* Print information about a candidate with WANT parameters and we found
3426 HAVE. */
3428 static void
3430 {
3435 }
3437 /* Print information about one overload candidate CANDIDATE. MSGSTR
3438 is the text to print before the candidate itself.
3440 NOTE: Unlike most diagnostic functions in GCC, MSGSTR is expected
3441 to have been run through gettext by the caller. This wart makes
3442 life simpler in print_z_candidates and for the translators. */
3444 static void
3447 {
3457 {
3468 else
3471 }
3478 else
3481 {
3484 }
3485 /* Give the user some information about why this candidate failed. */
3487 {
3491 {
3504 "cannot be converted to %qT with a qualification "
3510 "conversion function specialization to %qT is not an "
3515 /* We use template_unification_error_rejection if unification caused
3516 actual non-SFINAE errors, in which case we don't need to repeat
3517 them here. */
3519 {
3523 }
3524 /* Re-run template unification with diagnostics. */
3528 (make_tree_vec
3539 " a constructor taking a single argument of its own "
3543 {
3547 }
3551 "initialization from an expression of the same or derived "
3556 /* This candidate didn't have any issues or we failed to
3557 handle a particular code. Either way... */
3559 }
3560 }
3561 }
3563 static void
3565 {
3572 /* Remove non-viable deleted candidates. */
3575 {
3580 else
3582 }
3583 /* ...if there are any non-deleted ones. */
3587 /* There may be duplicates in the set of candidates. We put off
3588 checking this condition as long as possible, since we have no way
3589 to eliminate duplicates from a set of functions in less than n^2
3590 time. Now we are about to emit an error message, so it is more
3591 permissible to go slowly. */
3593 {
3595 /* Skip builtin candidates and conversion functions. */
3600 {
3604 else
3606 }
3607 }
3611 }
3613 /* USER_SEQ is a user-defined conversion sequence, beginning with a
3614 USER_CONV. STD_SEQ is the standard conversion sequence applied to
3615 the result of the conversion function to convert it to the final
3616 desired type. Merge the two sequences into a single sequence,
3617 and return the merged sequence. */
3621 {
3627 /* Find the end of the second conversion sequence. */
3629 {
3630 /* The entire sequence is a user-conversion sequence. */
3634 }
3636 /* Replace the identity conversion with the user conversion
3637 sequence. */
3641 }
3643 /* Handle overload resolution for initializing an object of class type from
3644 an initializer list. First we look for a suitable constructor that
3645 takes a std::initializer_list; if we don't find one, we then look for a
3646 non-list constructor.
3648 Parameters are as for add_candidates, except that the arguments are in
3649 the form of a CONSTRUCTOR (the initializer list) rather than a vector, and
3650 the RETURN_TYPE parameter is replaced by TOTYPE, the desired type. */
3652 static void
3659 tsubst_flags_t complain)
3660 {
3663 /* We're looking for a ctor for list-initialization. */
3665 /* And we don't allow narrowing conversions. We also use this flag to
3666 avoid the copy constructor call for copy-list-initialization. */
3672 /* Always use the default constructor if the list is empty (DR 990). */
3675 ;
3676 /* If the class has a list ctor, try passing the list as a single
3677 argument first, but only consider list ctors. */
3679 {
3686 }
3688 /* Expand the CONSTRUCTOR into a new argument vec. */
3696 /* We aren't looking for list-ctors anymore. */
3698 /* We allow more user-defined conversions within an init-list. */
3704 }
3706 /* Returns the best overload candidate to perform the requested
3707 conversion. This function is used for three the overloading situations
3708 described in [over.match.copy], [over.match.conv], and [over.match.ref].
3709 If TOTYPE is a REFERENCE_TYPE, we're trying to find a direct binding as
3710 per [dcl.init.ref], so we ignore temporary bindings. */
3714 tsubst_flags_t complain)
3715 {
3717 tree fromtype;
3731 /* We represent conversion within a hierarchy using RVALUE_CONV and
3732 BASE_CONV, as specified by [over.best.ics]; these become plain
3733 constructor calls, as specified in [dcl.init]. */
3738 /* Use lookup_fnfields_slot instead of lookup_fnfields to avoid
3739 creating a garbage BASELINK; constructors can't be inherited. */
3742 /* FIXME P0135 doesn't say what to do in C++17 about list-initialization from
3743 a single element. For now, let's handle constructors as before and also
3744 consider conversion operators from the element. */
3751 {
3756 {
3757 /* [class.conv.fct] A conversion function is never used to
3758 convert a (possibly cv-qualified) object to the (possibly
3759 cv-qualified) same object type (or a reference to it), to a
3760 (possibly cv-qualified) base class of that type (or a
3761 reference to it)... */
3762 }
3763 else
3765 }
3772 /* It's OK to bind a temporary for converting constructor arguments, but
3773 not in converting the return value of a conversion operator. */
3779 {
3784 /* We should never try to call the abstract or base constructor
3785 from here. */
3791 {
3792 /* List-initialization. */
3796 }
3797 else
3798 {
3802 }
3805 {
3808 /* If totype isn't a reference, and LOOKUP_NO_TEMP_BIND isn't
3809 set, then this is copy-initialization. In that case, "The
3810 result of the call is then used to direct-initialize the
3811 object that is the destination of the copy-initialization."
3812 [dcl.init]
3814 We represent this in the conversion sequence with an
3815 rvalue conversion, which means a constructor call. */
3818 cand->second_conv
3820 }
3821 }
3824 {
3826 /* FIXME see above about C++17. */
3828 else
3830 }
3833 {
3837 /* If we are called to convert to a reference type, we are trying to
3838 find a direct binding, so don't even consider temporaries. If
3839 we don't find a direct binding, the caller will try again to
3840 look for a temporary binding. */
3851 {
3853 conversion *ics
3855 rettype,
3858 complain);
3860 /* If LOOKUP_NO_TEMP_BIND isn't set, then this is
3861 copy-initialization. In that case, "The result of the
3862 call is then used to direct-initialize the object that is
3863 the destination of the copy-initialization." [dcl.init]
3865 We represent this in the conversion sequence with an
3866 rvalue conversion, which means a constructor call. But
3867 don't add a second rvalue conversion if there's already
3868 one there. Which there really shouldn't be, but it's
3869 harmless since we'd add it here anyway. */
3877 {
3881 }
3884 {
3885 /* 13.3.1.5: For direct-initialization, those explicit
3886 conversion functions that are not hidden within S and
3887 yield type T or a type that can be converted to type T
3888 with a qualification conversion (4.4) are also candidate
3889 functions. */
3890 /* 13.3.1.6 doesn't have a parallel restriction, but it should;
3891 I've raised this issue with the committee. --jason 9/2011 */
3894 }
3896 {
3898 cand->reason
3901 }
3904 {
3905 /* 13.3.3.1.2: If the user-defined conversion is specified by
3906 a specialization of a conversion function template, the
3907 second standard conversion sequence shall have exact match
3908 rank. */
3911 }
3912 }
3913 }
3917 {
3921 }
3925 {
3927 {
3931 }
3938 /* If there are viable candidates, don't set ICS_BAD_FLAG; an
3939 ambiguous conversion is no worse than another user-defined
3940 conversion. */
3943 }
3945 tree convtype;
3949 /* DR 5: [in the first step of copy-initialization]...if the function
3950 is a constructor, the call initializes a temporary of the
3951 cv-unqualified version of the destination type. */
3953 else
3955 /* Build the user conversion sequence. */
3956 conv = build_conv
3958 convtype,
3964 /* Remember that this was a list-initialization. */
3968 /* Combine it with the second conversion sequence. */
3973 }
3975 /* Wrapper for above. */
3977 tree
3979 tsubst_flags_t complain)
3980 {
3982 tree ret;
3988 {
3991 else
3992 {
3995 }
3996 }
3997 else
4002 }
4004 /* Subroutine of convert_nontype_argument.
4006 EXPR is an expression used in a context that requires a converted
4007 constant-expression, such as a template non-type parameter. Do any
4008 necessary conversions (that are permitted for converted
4009 constant-expressions) to convert it to the desired type.
4011 If conversion is successful, returns the converted expression;
4012 otherwise, returns error_mark_node. */
4014 tree
4016 {
4019 tree t;
4025 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4032 /* A converted constant expression of type T is an expression, implicitly
4033 converted to type T, where the converted expression is a constant
4034 expression and the implicit conversion sequence contains only
4036 * user-defined conversions,
4037 * lvalue-to-rvalue conversions (7.1),
4038 * array-to-pointer conversions (7.2),
4039 * function-to-pointer conversions (7.3),
4040 * qualification conversions (7.5),
4041 * integral promotions (7.6),
4042 * integral conversions (7.8) other than narrowing conversions (11.6.4),
4043 * null pointer conversions (7.11) from std::nullptr_t,
4044 * null member pointer conversions (7.12) from std::nullptr_t, and
4045 * function pointer conversions (7.13),
4047 and where the reference binding (if any) binds directly. */
4052 {
4054 {
4055 /* A conversion function is OK. If it isn't constexpr, we'll
4056 complain later that the argument isn't constant. */
4058 /* The lvalue-to-rvalue conversion is OK. */
4060 /* Array-to-pointer and function-to-pointer. */
4062 /* Function pointer conversions. */
4064 /* Qualification conversions. */
4070 {
4076 }
4086 /* Integral promotion or conversion. */
4089 /* Conversion from nullptr to pointer or pointer-to-member. */
4095 /* fall through. */
4100 }
4101 }
4103 /* Avoid confusing convert_nontype_argument by introducing
4104 a redundant conversion to the same reference type. */
4107 {
4111 }
4115 else
4118 /* Free all the conversions we allocated. */
4122 }
4124 /* Do any initial processing on the arguments to a function call. */
4128 {
4130 tree arg;
4133 {
4137 {
4141 }
4144 }
4146 }
4148 /* Perform overload resolution on FN, which is called with the ARGS.
4150 Return the candidate function selected by overload resolution, or
4151 NULL if the event that overload resolution failed. In the case
4152 that overload resolution fails, *CANDIDATES will be the set of
4153 candidates considered, and ANY_VIABLE_P will be set to true or
4154 false to indicate whether or not any of the candidates were
4155 viable.
4157 The ARGS should already have gone through RESOLVE_ARGS before this
4158 function is called. */
4165 {
4167 tree explicit_targs;
4178 /* Check FN. */
4185 {
4189 }
4191 /* Add the various candidate functions. */
4196 LOOKUP_NORMAL,
4202 else
4207 }
4209 /* Print an error message about being unable to build a call to FN with
4210 ARGS. ANY_VIABLE_P indicates whether any candidate functions could
4211 be located; CANDIDATES is a possibly empty list of such
4212 functions. */
4214 static void
4217 {
4220 {
4223 }
4232 else
4237 }
4239 /* Return an expression for a call to FN (a namespace-scope function,
4240 or a static member function) with the ARGS. This may change
4241 ARGS. */
4243 tree
4245 tsubst_flags_t complain)
4246 {
4250 tree result;
4253 {
4257 }
4262 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4266 complain);
4269 {
4271 {
4272 // If there is a single (non-viable) function candidate,
4273 // let the error be diagnosed by cp_build_function_call_vec.
4278 // Otherwise, emit notes for non-viable candidates.
4280 }
4282 }
4283 else
4284 {
4286 /* If fn is template_id_expr, the call has explicit template arguments
4287 (e.g. func<int>(5)), communicate this info to build_over_call
4288 through flags so that later we can use it to decide whether to warn
4289 about peculiar null pointer conversion. */
4291 {
4292 /* If overload resolution selects a specialization of a
4293 function concept for non-dependent template arguments,
4294 the expression is true if the constraints are satisfied
4295 and false otherwise.
4297 NOTE: This is an extension of Concepts Lite TS that
4298 allows constraints to be used in expressions. */
4300 {
4306 }
4309 }
4312 }
4314 /* Free all the conversions we allocated. */
4318 }
4320 /* Build a call to a global operator new. FNNAME is the name of the
4321 operator (either "operator new" or "operator new[]") and ARGS are
4322 the arguments provided. This may change ARGS. *SIZE points to the
4323 total number of bytes required by the allocation, and is updated if
4324 that is changed here. *COOKIE_SIZE is non-NULL if a cookie should
4325 be used. If this function determines that no cookie should be
4326 used, after all, *COOKIE_SIZE is set to NULL_TREE. If SIZE_CHECK
4327 is not NULL_TREE, it is evaluated before calculating the final
4328 array size, and if it fails, the array size is replaced with
4329 (size_t)-1 (usually triggering a std::bad_alloc exception). If FN
4330 is non-NULL, it will be set, upon return, to the allocation
4331 function called. */
4333 tree
4338 {
4340 tree fns;
4347 /* Set to (size_t)-1 if the size check fails. */
4349 {
4355 }
4361 /* Based on:
4363 [expr.new]
4365 If this lookup fails to find the name, or if the allocated type
4366 is not a class type, the allocation function's name is looked
4367 up in the global scope.
4369 we disregard block-scope declarations of "operator new". */
4374 {
4381 /* If no aligned allocation function matches, try again without the
4382 alignment. */
4383 }
4385 /* Figure out what function is being called. */
4388 complain);
4390 /* If no suitable function could be found, issue an error message
4391 and give up. */
4393 {
4397 }
4399 /* If a cookie is required, add some extra space. Whether
4400 or not a cookie is required cannot be determined until
4401 after we know which function was called. */
4403 {
4405 tree arg_types;
4408 /* Skip the size_t parameter. */
4410 /* Check the remaining parameters (if any). */
4414 ptr_type_node))
4416 /* If we need a cookie, adjust the number of bytes allocated. */
4418 {
4419 /* Update the total size. */
4422 {
4423 /* Set to (size_t)-1 if the size check fails. */
4427 }
4428 /* Update the argument list to reflect the adjusted size. */
4430 }
4431 else
4433 }
4435 /* Tell our caller which function we decided to call. */
4439 /* Build the CALL_EXPR. */
4441 }
4443 /* Build a new call to operator(). This may change ARGS. */
4445 static tree
4447 {
4464 {
4466 /* It's no good looking for an overloaded operator() on a
4467 pointer-to-member-function. */
4471 }
4474 {
4478 }
4479 else
4483 {
4487 }
4489 /* Get the high-water mark for the CONVERSION_OBSTACK. */
4493 {
4501 }
4506 {
4514 {
4521 add_template_conv_candidate
4525 else
4529 }
4530 }
4532 /* Be strict here because if we choose a bad conversion candidate, the
4533 errors we get won't mention the call context. */
4536 {
4538 {
4542 }
4544 }
4545 else
4546 {
4549 {
4551 {
4555 }
4557 }
4562 else
4563 {
4567 else
4568 {
4571 }
4574 }
4575 }
4577 /* Free all the conversions we allocated. */
4581 }
4583 /* Wrapper for above. */
4585 tree
4587 {
4588 tree ret;
4593 }
4595 /* Called by op_error to prepare format strings suitable for the error
4596 function. It concatenates a prefix (controlled by MATCH), ERRMSG,
4597 and a suffix (controlled by NTYPES). */
4601 {
4611 else
4615 }
4617 static void
4620 {
4625 {
4631 else
4643 else
4653 else
4664 else
4674 else
4679 else
4683 else
4688 }
4689 }
4691 /* Return the implicit conversion sequence that could be used to
4692 convert E1 to E2 in [expr.cond]. */
4696 {
4702 /* [expr.cond]
4704 If E2 is an lvalue: E1 can be converted to match E2 if E1 can be
4705 implicitly converted (clause _conv_) to the type "lvalue reference to
4706 T2", subject to the constraint that in the conversion the
4707 reference must bind directly (_dcl.init.ref_) to an lvalue.
4709 If E2 is an xvalue: E1 can be converted to match E2 if E1 can be
4710 implicitly converted to the type "rvalue reference to T2", subject to
4711 the constraint that the reference must bind directly. */
4713 {
4716 t1,
4717 e1,
4719 LOOKUP_NO_TEMP_BIND|LOOKUP_NO_RVAL_BIND
4721 complain);
4724 }
4726 /* If E2 is a prvalue or if neither of the conversions above can be done
4727 and at least one of the operands has (possibly cv-qualified) class
4728 type: */
4732 /* [expr.cond]
4734 If E1 and E2 have class type, and the underlying class types are
4735 the same or one is a base class of the other: E1 can be converted
4736 to match E2 if the class of T2 is the same type as, or a base
4737 class of, the class of T1, and the cv-qualification of T2 is the
4738 same cv-qualification as, or a greater cv-qualification than, the
4739 cv-qualification of T1. If the conversion is applied, E1 is
4740 changed to an rvalue of type T2 that still refers to the original
4741 source class object (or the appropriate subobject thereof). */
4744 {
4746 {
4751 else
4754 }
4755 else
4757 }
4758 else
4759 /* [expr.cond]
4761 Otherwise: E1 can be converted to match E2 if E1 can be implicitly
4762 converted to the type that expression E2 would have if E2 were
4763 converted to an rvalue (or the type it has, if E2 is an rvalue). */
4766 }
4768 /* Implement [expr.cond]. ARG1, ARG2, and ARG3 are the three
4769 arguments to the conditional expression. */
4771 static tree
4773 tsubst_flags_t complain)
4774 {
4775 tree arg2_type;
4776 tree arg3_type;
4785 /* As a G++ extension, the second argument to the conditional can be
4786 omitted. (So that `a ? : c' is roughly equivalent to `a ? a :
4787 c'.) If the second operand is omitted, make sure it is
4788 calculated only once. */
4790 {
4798 /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */
4801 else
4803 }
4805 /* If something has already gone wrong, just pass that fact up the
4806 tree. */
4816 {
4819 /* If arg1 is another cond_expr choosing between -1 and 0,
4820 then we can use its comparison. It may help to avoid
4821 additional comparison, produce more accurate diagnostics
4822 and enables folding. */
4832 /* force_rvalue can return error_mark on valid arguments. */
4843 {
4844 /* Rely on the error messages of the scalar version. */
4853 {
4861 }
4865 /* We could pass complain & tf_warning to unsafe_conversion_p,
4866 but the warnings (like Wsign-conversion) have already been
4867 given by the scalar build_conditional_expr_1. We still check
4868 unsafe_conversion_p to forbid truncating long long -> float. */
4870 {
4875 }
4877 {
4882 }
4892 }
4895 {
4901 {
4905 {
4911 }
4913 {
4919 }
4922 }
4923 }
4929 {
4932 "incompatible vector types in conditional expression: "
4936 }
4939 {
4942 }
4944 }
4946 /* [expr.cond]
4948 The first expression is implicitly converted to bool (clause
4949 _conv_). */
4951 LOOKUP_NORMAL);
4955 /* [expr.cond]
4957 If either the second or the third operand has type (possibly
4958 cv-qualified) void, then the lvalue-to-rvalue (_conv.lval_),
4959 array-to-pointer (_conv.array_), and function-to-pointer
4960 (_conv.func_) standard conversions are performed on the second
4961 and third operands. */
4965 {
4966 /* Do the conversions. We don't these for `void' type arguments
4967 since it can't have any effect and since decay_conversion
4968 does not handle that case gracefully. */
4976 /* [expr.cond]
4978 One of the following shall hold:
4980 --The second or the third operand (but not both) is a
4981 throw-expression (_except.throw_); the result is of the
4982 type of the other and is an rvalue.
4984 --Both the second and the third operands have type void; the
4985 result is of type void and is an rvalue.
4987 We must avoid calling force_rvalue for expressions of type
4988 "void" because it will complain that their value is being
4989 used. */
4992 {
4994 {
4998 }
5001 }
5004 {
5006 {
5010 }
5013 }
5016 else
5017 {
5019 {
5022 "second operand to the conditional operator "
5023 "is of type %<void%>, but the third operand is "
5025 else
5027 "third operand to the conditional operator "
5028 "is of type %<void%>, but the second operand is "
5030 }
5032 }
5036 }
5037 /* [expr.cond]
5039 Otherwise, if the second and third operand have different types,
5040 and either has (possibly cv-qualified) class type, or if both are
5041 glvalues of the same value category and the same type except for
5042 cv-qualification, an attempt is made to convert each of those operands
5043 to the type of the other. */
5047 arg3_type)
5050 {
5055 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5061 /* [expr.cond]
5063 If both can be converted, or one can be converted but the
5064 conversion is ambiguous, the program is ill-formed. If
5065 neither can be converted, the operands are left unchanged and
5066 further checking is performed as described below. If exactly
5067 one conversion is possible, that conversion is applied to the
5068 chosen operand and the converted operand is used in place of
5069 the original operand for the remainder of this section. */
5074 {
5076 {
5083 else
5085 }
5087 }
5089 {
5093 /* Even if CONV2 is a valid conversion, the result of the
5094 conversion may be invalid. For example, if ARG3 has type
5095 "volatile X", and X does not have a copy constructor
5096 accepting a "volatile X&", then even if ARG2 can be
5097 converted to X, the conversion will fail. */
5101 }
5103 {
5110 }
5112 /* Free all the conversions we allocated. */
5118 /* If, after the conversion, both operands have class type,
5119 treat the cv-qualification of both operands as if it were the
5120 union of the cv-qualification of the operands.
5122 The standard is not clear about what to do in this
5123 circumstance. For example, if the first operand has type
5124 "const X" and the second operand has a user-defined
5125 conversion to "volatile X", what is the type of the second
5126 operand after this step? Making it be "const X" (matching
5127 the first operand) seems wrong, as that discards the
5128 qualification without actually performing a copy. Leaving it
5129 as "volatile X" seems wrong as that will result in the
5130 conditional expression failing altogether, even though,
5131 according to this step, the one operand could be converted to
5132 the type of the other. */
5140 }
5142 /* [expr.cond]
5144 If the second and third operands are glvalues of the same value
5145 category and have the same type, the result is of that type and
5146 value category. */
5150 {
5155 }
5157 /* [expr.cond]
5159 Otherwise, the result is an rvalue. If the second and third
5160 operand do not have the same type, and either has (possibly
5161 cv-qualified) class type, overload resolution is used to
5162 determine the conversions (if any) to be applied to the operands
5163 (_over.match.oper_, _over.built_). */
5167 {
5172 /* Rearrange the arguments so that add_builtin_candidate only has
5173 to know about two args. In build_builtin_candidate, the
5174 arguments are unscrambled. */
5179 COND_EXPR,
5180 NOP_EXPR,
5182 args,
5185 /* [expr.cond]
5187 If the overload resolution fails, the program is
5188 ill-formed. */
5191 {
5196 }
5199 {
5201 {
5204 }
5206 }
5208 /* [expr.cond]
5210 Otherwise, the conversions thus determined are applied, and
5211 the converted operands are used in place of the original
5212 operands for the remainder of this section. */
5221 }
5223 /* [expr.cond]
5225 Lvalue-to-rvalue (_conv.lval_), array-to-pointer (_conv.array_),
5226 and function-to-pointer (_conv.func_) standard conversions are
5227 performed on the second and third operands.
5229 We need to force the lvalue-to-rvalue conversion here for class types,
5230 so we get TARGET_EXPRs; trying to deal with a COND_EXPR of class rvalues
5231 that isn't wrapped with a TARGET_EXPR plays havoc with exception
5232 regions. */
5245 /* [expr.cond]
5247 After those conversions, one of the following shall hold:
5249 --The second and third operands have the same type; the result is of
5250 that type. */
5253 /* [expr.cond]
5255 --The second and third operands have arithmetic or enumeration
5256 type; the usual arithmetic conversions are performed to bring
5257 them to a common type, and the result is of that type. */
5262 {
5263 /* In this case, there is always a common type. */
5265 arg3_type);
5268 "implicit conversion from %qH to %qI to "
5270 loc);
5274 {
5278 /* Two enumerators from the same enumeration can have different
5284 }
5291 {
5295 }
5299 }
5300 /* [expr.cond]
5302 --The second and third operands have pointer type, or one has
5303 pointer type and the other is a null pointer constant; pointer
5304 conversions (_conv.ptr_) and qualification conversions
5305 (_conv.qual_) are performed to bring them to their composite
5306 pointer type (_expr.rel_). The result is of the composite
5307 pointer type.
5309 --The second and third operands have pointer to member type, or
5310 one has pointer to member type and the other is a null pointer
5311 constant; pointer to member conversions (_conv.mem_) and
5312 qualification conversions (_conv.qual_) are performed to bring
5313 them to a common type, whose cv-qualification shall match the
5314 cv-qualification of either the second or the third operand.
5315 The result is of the common type. */
5323 {
5326 complain);
5331 }
5334 {
5339 }
5344 valid_operands:
5347 /* If the ARG2 and ARG3 are the same and don't have side-effects,
5348 warn here, because the COND_EXPR will be turned into ARG2. */
5355 /* We can't use result_type below, as fold might have returned a
5356 throw_expr. */
5359 {
5360 /* Expand both sides into the same slot, hopefully the target of
5361 the ?: expression. We used to check for TARGET_EXPRs here,
5362 but now we sometimes wrap them in NOP_EXPRs so the test would
5363 fail. */
5366 /* If this expression is an rvalue, but might be mistaken for an
5367 lvalue, we must add a NON_LVALUE_EXPR. */
5369 }
5370 else
5374 }
5376 /* Wrapper for above. */
5378 tree
5380 tsubst_flags_t complain)
5381 {
5382 tree ret;
5387 }
5389 /* OPERAND is an operand to an expression. Perform necessary steps
5390 required before using it. If OPERAND is NULL_TREE, NULL_TREE is
5391 returned. */
5393 static tree
5395 {
5397 {
5400 /* Make sure the template type is instantiated now. */
5402 }
5405 }
5407 /* Add each of the viable functions in FNS (a FUNCTION_DECL or
5408 OVERLOAD) to the CANDIDATES, returning an updated list of
5409 CANDIDATES. The ARGS are the arguments provided to the call;
5410 if FIRST_ARG is non-null it is the implicit object argument,
5411 otherwise the first element of ARGS is used if needed. The
5412 EXPLICIT_TARGS are explicit template arguments provided.
5413 TEMPLATE_ONLY is true if only template functions should be
5414 considered. CONVERSION_PATH, ACCESS_PATH, and FLAGS are as for
5415 add_function_candidate. */
5417 static void
5419 tree return_type,
5424 tsubst_flags_t complain)
5425 {
5426 tree ctype;
5430 unification_kind_t strict;
5435 /* Precalculate special handling of constructors and conversion ops. */
5438 {
5442 /* We're doing return_type(x). */
5444 else
5445 /* We're doing x.operator return_type(). */
5447 /* [over.match.funcs] For conversion functions, the function
5448 is considered to be a member of the class of the implicit
5449 object argument for the purpose of defining the type of
5450 the implicit object parameter. */
5452 }
5453 else
5454 {
5456 {
5458 /* For list-initialization we consider explicit constructors
5459 and complain if one is chosen. */
5460 check_converting
5463 }
5466 }
5470 else
5471 /* Delay creating the implicit this parameter until it is needed. */
5475 {
5487 {
5488 /* Figure out where the object arg comes from. If this
5489 function is a non-static member and we didn't get an
5490 implicit object argument, move it out of args. */
5492 {
5494 tree arg;
5501 }
5505 }
5509 fn,
5510 ctype,
5511 explicit_targs,
5512 fn_first_arg,
5513 fn_args,
5514 return_type,
5515 access_path,
5516 conversion_path,
5517 flags,
5518 strict,
5519 complain);
5522 fn,
5523 ctype,
5524 fn_first_arg,
5525 fn_args,
5526 access_path,
5527 conversion_path,
5528 flags,
5529 complain);
5530 }
5531 }
5533 /* Returns 1 if P0145R2 says that the LHS of operator CODE is evaluated first,
5534 -1 if the RHS is evaluated first, or 0 if the order is unspecified. */
5536 static int
5538 {
5540 {
5541 // 5. b @= a
5545 // 6. a[b]
5549 // 1. a.b
5550 // Not overloadable (yet).
5551 // 2. a->b
5552 // Only one argument.
5553 // 3. a->*b
5555 // 7. a << b
5557 // 8. a >> b
5563 }
5564 }
5566 static tree
5569 {
5590 {
5593 }
5600 {
5605 /* Use build_op_new_call and build_op_delete_call instead. */
5609 /* Use build_op_call instead. */
5616 /* These are saved for the sake of warn_logical_operator. */
5626 /* These are saved for the sake of maybe_warn_bool_compare. */
5631 /* =, ->, [], () must be non-static member functions. */
5635 /* FALLTHRU */
5643 }
5649 /* Use build_conditional_expr instead. */
5665 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5668 /* Add namespace-scope operators to the list of functions to
5669 consider. */
5671 {
5677 }
5683 /* Add class-member operators to the candidate set. */
5685 {
5686 tree fns;
5690 {
5693 }
5701 }
5702 /* Per 13.3.1.2/3, 2nd bullet, if no operand has a class type, then
5703 only non-member functions that have type T1 or reference to
5704 cv-qualified-opt T1 for the first argument, if the first argument
5705 has an enumeration type, or T2 or reference to cv-qualified-opt
5706 T2 for the second argument, if the second argument has an
5707 enumeration type. Filter out those that don't match. */
5709 {
5713 {
5723 {
5729 && (same_type_ignoring_top_level_qualifiers_p
5734 }
5736 /* No argument has an appropriate type, so remove this
5737 candidate function from the list. */
5739 {
5742 }
5743 }
5744 }
5750 {
5753 /* For these, the built-in candidates set is empty
5754 [over.match.oper]/3. We don't want non-strict matches
5755 because exact matches are always possible with built-in
5756 operators. The built-in candidate set for COMPONENT_REF
5757 would be empty too, but since there are no such built-in
5758 operators, we accept non-strict matches for them. */
5765 }
5769 {
5771 {
5774 /* Don't try anything fancy if we're not allowed to produce
5775 errors. */
5779 /* Look for an `operator++ (int)'. Pre-1985 C++ didn't
5780 distinguish between prefix and postfix ++ and
5781 operator++() was used for both, so we allow this with
5782 -fpermissive. */
5783 else
5784 {
5790 }
5797 else
5803 /* The caller will deal with these. */
5813 {
5814 /* If one of the arguments of the operator represents
5815 an invalid use of member function pointer, try to report
5816 a meaningful error ... */
5821 else
5822 {
5823 /* ... Otherwise, report the more generic
5824 "no matching operator found" error */
5827 }
5828 }
5831 }
5832 }
5833 else
5834 {
5837 {
5839 {
5842 }
5844 }
5846 {
5852 else
5858 {
5863 /* This prevents build_new_function_call from discarding this
5864 function during instantiation of the enclosing template. */
5867 /* Specify evaluation order as per P0145R2. */
5870 {
5881 }
5882 }
5883 }
5884 else
5885 {
5886 /* Give any warnings we noticed during overload resolution. */
5888 {
5892 }
5894 /* Check for comparison of different enum types. */
5896 {
5908 {
5912 }
5916 }
5918 /* We need to strip any leading REF_BIND so that bitfields
5919 don't cause errors. This should not remove any important
5920 conversions, because builtins don't apply to class
5921 objects directly. */
5928 {
5932 else
5935 /* We need to call warn_logical_operator before
5936 converting arg2 to a boolean_type, but after
5937 decaying an enumerator to its value. */
5944 }
5946 {
5951 }
5953 }
5954 }
5956 user_defined_result_ready:
5958 /* Free all the conversions we allocated. */
5964 builtin:
5966 {
5981 /* Fall through. */
5994 /* Fall through. */
6027 complain),
6030 /* The caller will deal with these. */
6038 }
6040 }
6042 /* Wrapper for above. */
6044 tree
6048 {
6049 tree ret;
6055 }
6057 /* CALL was returned by some call-building function; extract the actual
6058 CALL_EXPR from any bits that have been tacked on, e.g. by
6059 convert_from_reference. */
6061 tree
6063 {
6074 }
6076 /* Returns true if FN has two parameters, of which the second has type
6077 size_t. */
6079 static bool
6081 {
6093 }
6095 /* True if T, an allocation function, has std::align_val_t as its second
6096 argument. */
6098 bool
6100 {
6106 }
6108 /* Returns true iff T, an element of an OVERLOAD chain, is a usual deallocation
6109 function (3.7.4.2 [basic.stc.dynamic.deallocation]) with a parameter of
6110 std::align_val_t. */
6112 static bool
6114 {
6118 /* A template instance is never a usual deallocation function,
6119 regardless of its signature. */
6135 }
6137 /* Returns true iff T, an element of an OVERLOAD chain, is a usual
6138 deallocation function (3.7.4.2 [basic.stc.dynamic.deallocation]). */
6140 bool
6142 {
6143 /* A template instance is never a usual deallocation function,
6144 regardless of its signature. */
6149 /* If a class T has a member deallocation function named operator delete
6150 with exactly one parameter, then that function is a usual
6151 (non-placement) deallocation function. If class T does not declare
6152 such an operator delete but does declare a member deallocation
6153 function named operator delete with exactly two parameters, the second
6154 of which has type std::size_t (18.2), then this function is a usual
6155 deallocation function. */
6167 }
6169 /* Build a call to operator delete. This has to be handled very specially,
6170 because the restrictions on what signatures match are different from all
6171 other call instances. For a normal delete, only a delete taking (void *)
6172 or (void *, size_t) is accepted. For a placement delete, only an exact
6173 match with the placement new is accepted.
6175 CODE is either DELETE_EXPR or VEC_DELETE_EXPR.
6176 ADDR is the pointer to be deleted.
6177 SIZE is the size of the memory block to be deleted.
6178 GLOBAL_P is true if the delete-expression should not consider
6179 class-specific delete operators.
6180 PLACEMENT is the corresponding placement new call, or NULL_TREE.
6182 If this call to "operator delete" is being generated as part to
6183 deallocate memory allocated via a new-expression (as per [expr.new]
6184 which requires that if the initialization throws an exception then
6185 we call a deallocation function), then ALLOC_FN is the allocation
6186 function. */
6188 tree
6192 {
6206 /* In [class.free]
6208 If the result of the lookup is ambiguous or inaccessible, or if
6209 the lookup selects a placement deallocation function, the
6210 program is ill-formed.
6212 Therefore, we ask lookup_fnfields to complain about ambiguity. */
6213 {
6217 }
6218 else
6224 /* Strip const and volatile from addr. */
6228 {
6229 /* "A declaration of a placement deallocation function matches the
6230 declaration of a placement allocation function if it has the same
6231 number of parameters and, after parameter transformations (8.3.5),
6232 all parameter types except the first are identical."
6234 So we build up the function type we want and ask instantiate_type
6235 to get it for us. */
6246 /* "If the lookup finds the two-parameter form of a usual deallocation
6247 function (3.7.4.2) and that function, considered as a placement
6248 deallocation function, would have been selected as a match for the
6249 allocation function, the program is ill-formed." */
6251 {
6259 /* But if the class has an operator delete (void *), then that is
6260 the usual deallocation function, so we shouldn't complain
6261 about using the operator delete (void *, size_t). */
6265 {
6270 }
6271 /* Before C++14 a two-parameter global deallocation function is
6272 always a placement deallocation function, but warn if
6273 -Wc++14-compat. */
6275 {
6280 }
6283 {
6285 {
6286 /* Only mention C++14 for namespace-scope delete. */
6289 else
6291 "%qD is a usual (non-placement) deallocation "
6293 }
6294 }
6295 else
6297 ok:;
6298 }
6299 }
6300 else
6301 /* "Any non-placement deallocation function matches a non-placement
6302 allocation function. If the lookup finds a single matching
6303 deallocation function, that function will be called; otherwise, no
6304 deallocation function will be called." */
6306 {
6309 {
6311 {
6314 }
6316 /* -- If the type has new-extended alignment, a function with a
6317 parameter of type std::align_val_t is preferred; otherwise a
6318 function without such a parameter is preferred. If exactly one
6319 preferred function is found, that function is selected and the
6320 selection process terminates. If more than one preferred
6321 function is found, all non-preferred functions are eliminated
6322 from further consideration. */
6324 {
6330 {
6334 }
6335 }
6337 /* -- If the deallocation functions have class scope, the one
6338 without a parameter of type std::size_t is selected. */
6343 /* -- If the type is complete and if, for the second alternative
6344 (delete array) only, the operand is a pointer to a class type
6345 with a non-trivial destructor or a (possibly multi-dimensional)
6346 array thereof, the function with a parameter of type std::size_t
6347 is selected.
6349 -- Otherwise, it is unspecified whether a deallocation function
6350 with a parameter of type std::size_t is selected. */
6351 else
6352 {
6356 /* We need a cookie to determine the array size. */
6358 }
6364 }
6365 }
6367 /* If we have a matching function, call it. */
6369 {
6372 /* If the FN is a member function, make sure that it is
6373 accessible. */
6376 complain);
6378 /* Core issue 901: It's ok to new a type with deleted delete. */
6383 {
6384 /* The placement args might not be suitable for overload
6385 resolution at this point, so build the call directly. */
6395 }
6396 else
6397 {
6398 tree ret;
6404 {
6407 }
6411 }
6412 }
6414 /* [expr.new]
6416 If no unambiguous matching deallocation function can be found,
6417 propagating the exception does not cause the object's memory to
6418 be freed. */
6420 {
6424 alloc_fn);
6426 }
6432 }
6434 /* If the current scope isn't allowed to access DECL along
6435 BASETYPE_PATH, give an error. The most derived class in
6436 BASETYPE_PATH is the one used to qualify DECL. DIAG_DECL is
6437 the declaration to use in the error diagnostic. */
6439 bool
6442 {
6447 {
6448 /* 7.3.3/18: The additional constructors are accessible if they would be
6449 accessible when used to construct an object of the corresponding base
6450 class. */
6454 }
6457 {
6459 {
6463 {
6469 }
6471 {
6477 }
6478 else
6479 {
6484 }
6485 }
6487 }
6490 }
6492 /* Initialize a temporary of type TYPE with EXPR. The FLAGS are a
6493 bitwise or of LOOKUP_* values. If any errors are warnings are
6494 generated, set *DIAGNOSTIC_FN to "error" or "warning",
6495 respectively. If no diagnostics are generated, set *DIAGNOSTIC_FN
6496 to NULL. */
6498 static tree
6501 {
6507 /* If the source is a packed field, calling the copy constructor will require
6508 binding the field to the reference parameter to the copy constructor, and
6509 we'll end up with an infinite loop. If we can use a bitwise copy, then
6510 do that now. */
6526 }
6528 /* Perform warnings about peculiar, but valid, conversions from/to NULL.
6529 EXPR is implicitly converted to type TOTYPE.
6530 FN and ARGNUM are used for diagnostics. */
6532 static void
6534 {
6535 /* Issue warnings about peculiar, but valid, uses of NULL. */
6538 {
6539 source_location loc =
6546 else
6549 }
6551 /* Issue warnings if "false" is converted to a NULL pointer */
6554 {
6557 "converting %<false%> to pointer type for argument %P "
6559 else
6562 }
6563 }
6565 /* We gave a diagnostic during a conversion. If this was in the second
6566 standard conversion sequence of a user-defined conversion sequence, say
6567 which user-defined conversion. */
6569 static void
6571 {
6575 {
6579 }
6580 }
6582 /* Locate the parameter with the given index within FNDECL.
6583 ARGNUM is zero based, -1 indicates the `this' argument of a method.
6584 Return the location of the FNDECL itself if there are problems. */
6586 static location_t
6588 {
6590 tree param;
6592 /* Locate param by index within DECL_ARGUMENTS (fndecl). */
6596 ;
6598 /* If something went wrong (e.g. if we have a builtin and thus no arguments),
6599 return the location of FNDECL. */
6604 }
6606 /* Perform the conversions in CONVS on the expression EXPR. FN and
6607 ARGNUM are used for diagnostics. ARGNUM is zero based, -1
6608 indicates the `this' argument of a method. INNER is nonzero when
6609 being called to continue a conversion chain. It is negative when a
6610 reference binding will be applied, positive otherwise. If
6611 ISSUE_CONVERSION_WARNINGS is true, warnings about suspicious
6612 conversions will be emitted if appropriate. If C_CAST_P is true,
6613 this conversion is coming from a C-style cast; in that case,
6614 conversions to inaccessible bases are permitted. */
6616 static tree
6620 {
6622 diagnostic_t diag_kind;
6638 {
6642 /* Give a helpful error if this is bad because of excess braces. */
6647 {
6653 }
6655 /* Give a helpful error if this is bad because a conversion to bool
6656 from std::nullptr_t requires direct-initialization. */
6664 {
6666 {
6669 totype);
6675 complain);
6679 complain);
6680 else
6686 }
6688 {
6692 complain);
6694 }
6699 complain);
6702 }
6711 }
6717 {
6719 {
6723 /* We chose the surrogate function from add_conv_candidate, now we
6724 actually need to build the conversion. */
6730 /* When converting from an init list we consider explicit
6731 constructors, but actually trying to call one is an error. */
6734 /* Unless this is for direct-list-initialization. */
6736 /* And in C++98 a default constructor can't be explicit. */
6738 {
6744 {
6750 }
6751 else
6754 }
6756 /* If we're initializing from {}, it's value-initialization. */
6760 {
6765 {
6768 }
6770 }
6774 /* Pass LOOKUP_NO_CONVERSION so rvalue/base handling knows not to allow
6775 any more UDCs. */
6777 complain);
6779 /* If this is a constructor or a function returning an aggr type,
6780 we need to build up a TARGET_EXPR. */
6782 {
6785 /* Remember that this was list-initialization. */
6788 }
6791 }
6794 {
6800 else
6802 }
6809 /* We leave bad_p off ck_ambig because overload resolution considers
6810 it valid, it just fails when we try to perform it. So we need to
6811 check complain here, too. */
6813 {
6814 /* Call build_user_type_conversion again for the error. */
6816 complain);
6820 }
6824 {
6825 /* Conversion to std::initializer_list<T>. */
6833 /* Convert all the elements. */
6835 {
6846 }
6847 /* Build up the array. */
6848 elttype = cp_build_qualified_type
6852 /* Take the address explicitly rather than via decay_conversion
6853 to avoid the error about taking the address of a temporary. */
6859 /* Build up the initializer_list object. */
6867 }
6871 {
6880 }
6883 complain);
6890 };
6894 c_cast_p,
6895 complain);
6900 {
6904 {
6906 {
6911 }
6913 }
6918 /* Don't introduce copies when passing arguments along to the inherited
6919 constructor. */
6921 && flag_new_inheriting_ctors
6925 /* Fall through. */
6928 {
6929 /* We are going to bind a reference directly to a base-class
6930 subobject of EXPR. */
6931 /* Build an expression for `*((base*) &expr)'. */
6935 }
6937 /* Copy-initialization where the cv-unqualified version of the source
6938 type is the same class as, or a derived class of, the class of the
6939 destination [is treated as direct-initialization]. [dcl.init] */
6942 /* This conversion is being done in the context of a user-defined
6943 conversion (i.e. the second step of copy-initialization), so
6944 don't allow any more. */
6946 else
6949 /* standard_conversion got LOOKUP_PREFER_RVALUE. */
6953 /* Copy-list-initialization doesn't actually involve a copy. */
6957 {
6962 }
6967 {
6971 {
6984 else
6991 }
6993 /* If necessary, create a temporary.
6995 VA_ARG_EXPR and CONSTRUCTOR expressions are special cases
6996 that need temporaries, even when their types are reference
6997 compatible with the type of reference being bound, so the
6998 upcoming call to cp_build_addr_expr doesn't fail. */
7002 {
7003 /* Otherwise, a temporary of type "cv1 T1" is created and
7004 initialized from the initializer expression using the rules
7005 for a non-reference copy-initialization (8.5). */
7014 {
7015 /* If the reference is volatile or non-const, we
7016 cannot create a temporary. */
7023 else
7027 }
7028 /* If the source is a packed field, and we must use a copy
7029 constructor, then building the target expr will require
7030 binding the field to the reference parameter to the
7031 copy constructor, and we'll end up with an infinite
7032 loop. If we can use a bitwise copy, then we'll be
7033 OK. */
7037 {
7041 }
7043 {
7046 }
7048 }
7050 /* Take the address of the thing to which we will bind the
7051 reference. */
7056 /* Convert it to a pointer to the type referred to by the
7057 reference. This will adjust the pointer if a derived to
7058 base conversion is being performed. */
7061 /* Convert the pointer to the desired reference type. */
7063 }
7069 /* ??? Should the address of a transaction-safe pointer point to the TM
7070 clone, and this conversion look up the primary function? */
7074 /* Warn about deprecated conversion if appropriate. */
7090 }
7098 else
7102 }
7104 /* ARG is being passed to a varargs function. Perform any conversions
7105 required. Return the converted value. */
7107 tree
7109 {
7110 tree arg_type;
7113 /* [expr.call]
7115 The lvalue-to-rvalue, array-to-pointer, and function-to-pointer
7116 standard conversions are performed. */
7119 /* [expr.call]
7121 If the argument has integral or enumeration type that is subject
7122 to the integral promotions (_conv.prom_), or a floating point
7123 type that is subject to the floating point promotion
7124 (_conv.fpprom_), the value of the argument is converted to the
7125 promoted type before the call. */
7130 {
7134 "implicit conversion from %qH to %qI when passing "
7138 }
7142 {
7144 {
7146 complain);
7156 }
7157 else
7159 }
7165 /* In a template (or ill-formed code), we can have an incomplete type
7166 even after require_complete_type_sfinae, in which case we don't know
7167 whether it has trivial copy or not. */
7170 {
7171 /* [expr.call] 5.2.2/7:
7172 Passing a potentially-evaluated argument of class type (Clause 9)
7173 with a non-trivial copy constructor or a non-trivial destructor
7174 with no corresponding parameter is conditionally-supported, with
7175 implementation-defined semantics.
7177 We support it as pass-by-invisible-reference, just like a normal
7178 value parameter.
7180 If the call appears in the context of a sizeof expression,
7181 it is not potentially-evaluated. */
7184 {
7188 "passing objects of non-trivially-copyable "
7190 arg_type);
7192 }
7193 /* Build up a real lvalue-to-rvalue conversion in case the
7194 copy constructor is trivial but not callable. */
7198 }
7201 }
7203 /* va_arg (EXPR, TYPE) is a builtin. Make sure it is not abused. */
7205 tree
7207 {
7209 {
7213 }
7223 {
7226 }
7230 {
7231 /* conditionally-supported behavior [expr.call] 5.2.2/7. Let's treat
7232 it as pass by invisible reference. */
7234 "receiving objects of non-trivially-copyable type %q#T "
7240 }
7244 /* Wrap the VA_ARG_EXPR in a TARGET_EXPR now so other code doesn't need to
7245 know how to handle it. */
7248 }
7250 /* TYPE has been given to va_arg. Apply the default conversions which
7251 would have happened when passed via ellipsis. Return the promoted
7252 type, or the passed type if there is no change. */
7254 tree
7256 {
7257 tree promote;
7259 /* Perform the array-to-pointer and function-to-pointer
7260 conversions. */
7268 }
7270 /* ARG is a default argument expression being passed to a parameter of
7271 the indicated TYPE, which is a parameter to FN. PARMNUM is the
7272 zero-based argument number. Do any required conversions. Return
7273 the converted value. */
7276 void
7280 void
7284 tree
7286 tsubst_flags_t complain)
7287 {
7289 tree t;
7291 /* See through clones. */
7293 /* And inheriting ctors. */
7297 /* Detect recursion. */
7300 {
7304 }
7306 /* If the ARG is an unparsed default argument expression, the
7307 conversion cannot be performed. */
7309 {
7314 }
7321 /* Due to:
7323 [dcl.fct.default]
7325 The names in the expression are bound, and the semantic
7326 constraints are checked, at the point where the default
7327 expressions appears.
7329 we must not perform access checks here. */
7331 /* We must make a copy of ARG, in case subsequent processing
7332 alters any part of it. */
7336 complain);
7343 }
7345 /* Returns the type which will really be used for passing an argument of
7346 type TYPE. */
7348 tree
7350 {
7351 /* Pass classes with copy ctors by invisible reference. */
7353 {
7355 /* There are no other pointers to this temporary. */
7357 }
7365 }
7367 /* Actually perform the appropriate conversion. */
7369 tree
7371 {
7372 tree bitfield_type;
7374 /* If VAL is a bitfield, then -- since it has already been converted
7375 to TYPE -- it cannot have a precision greater than TYPE.
7377 If it has a smaller precision, we must widen it here. For
7378 example, passing "int f:3;" to a function expecting an "int" will
7379 not result in any conversion before this point.
7381 If the precision is the same we must not risk widening. For
7382 example, the COMPONENT_REF for a 32-bit "long long" bitfield will
7383 often have type "int", even though the C++ type for the field is
7384 "long long". If the value is being passed to a function
7385 expecting an "int", then no conversions will be required. But,
7386 if we call convert_bitfield_to_declared_type, the bitfield will
7387 be converted to "long long". */
7394 ;
7395 /* Pass classes with copy ctors by invisible reference. */
7404 {
7406 {
7414 "argument of function call might be a candidate "
7416 }
7418 }
7420 }
7422 /* Returns non-zero iff FN is a function with magic varargs, i.e. ones for
7423 which just decay_conversion or no conversions at all should be done.
7424 This is true for some builtins which don't act like normal functions.
7425 Return 2 if no conversions at all should be done, 1 if just
7426 decay_conversion. Return 3 for special treatment of the 3rd argument
7427 for __builtin_*_overflow_p. */
7429 int
7431 {
7434 {
7449 }
7452 }
7454 /* Returns the decl of the dispatcher function if FN is a function version. */
7456 tree
7458 {
7468 {
7472 }
7477 }
7479 /* fn is a function version dispatcher that is marked used. Mark all the
7480 semantically identical function versions it will dispatch as used. */
7482 void
7484 {
7501 /* All semantically identical versions are chained. Traverse and mark each
7502 one of them as used. */
7505 {
7508 }
7509 }
7511 /* Build a call to "the copy constructor" for the type of A, even if it
7512 wouldn't be selected by normal overload resolution. Used for
7513 diagnostics. */
7515 static tree
7517 {
7528 }
7530 /* Return true iff T refers to a base field. */
7532 static bool
7534 {
7543 }
7545 /* We can't elide a copy from a function returning by value to a base
7546 subobject, as the callee might clobber tail padding. Return true iff this
7547 could be that case. */
7549 static bool
7551 {
7552 /* Copy elision only happens with a TARGET_EXPR. */
7556 /* It's safe to elide the copy for a class with no tail padding. */
7559 /* It's safe to elide the copy if we aren't initializing a base object. */
7563 /* build_compound_expr pushes COMPOUND_EXPR inside TARGET_EXPR. */
7568 }
7570 /* Subroutine of the various build_*_call functions. Overload resolution
7571 has chosen a winning candidate CAND; build up a CALL_EXPR accordingly.
7572 ARGS is a TREE_LIST of the unconverted arguments to the call. FLAGS is a
7573 bitmask of various LOOKUP_* flags which apply to the call itself. */
7575 static tree
7577 {
7585 tree val;
7594 /* In a template, there is no need to perform all of the work that
7595 is normally done. We are only interested in the type of the call
7596 expression, i.e., the return type of the function. Any semantic
7597 errors will be deferred until the template is instantiated. */
7599 {
7601 tree return_type;
7612 else
7613 {
7616 tree arg;
7624 }
7634 }
7636 /* Give any warnings we noticed during overload resolution. */
7638 {
7642 }
7644 /* OK, we're actually calling this inherited constructor; set its deletedness
7645 appropriately. We can get away with doing this here because calling is
7646 the only way to refer to a constructor. */
7650 /* Make =delete work with SFINAE. */
7655 {
7656 tree access_fn;
7657 /* If FN is a template function, two cases must be considered.
7658 For example:
7660 struct A {
7661 protected:
7662 template <class T> void f();
7663 };
7664 template <class T> struct B {
7665 protected:
7666 void g();
7667 };
7668 struct C : A, B<int> {
7669 using A::f; // #1
7670 using B<int>::g; // #2
7671 };
7673 In case #1 where `A::f' is a member template, DECL_ACCESS is
7674 recorded in the primary template but not in its specialization.
7675 We check access of FN using its primary template.
7677 In case #2, where `B<int>::g' has a DECL_TEMPLATE_INFO simply
7678 because it is a member of class template B, DECL_ACCESS is
7679 recorded in the specialization `B<int>::g'. We cannot use its
7680 primary template because `B<T>::g' and `B<int>::g' may have
7681 different access. */
7685 else
7690 }
7692 /* If we're checking for implicit delete, don't bother with argument
7693 conversions. */
7695 {
7697 {
7701 }
7705 /* Reject bad conversions now. */
7707 /* else continue to get conversion error. */
7708 }
7710 /* N3276 magic doesn't apply to nested calls. */
7713 /* No-Cleanup doesn't apply to nested calls either. */
7717 /* Find maximum size of vector to hold converted arguments. */
7724 /* The implicit parameters to a constructor are not considered by overload
7725 resolution, and must be of the proper type. */
7727 {
7728 tree object_arg;
7730 {
7733 }
7734 else
7735 {
7738 }
7741 /* We should never try to call the abstract constructor. */
7745 {
7749 }
7752 {
7753 /* The implicit move specified in 15.8.3/3 fails "...if the type of
7754 the first parameter of the selected constructor is not an rvalue
7755 reference to the object’s type (possibly cv-qualified)...." */
7762 }
7763 }
7764 /* Bypass access control for 'this' parameter. */
7766 {
7769 ? first_arg
7772 tree converted_arg;
7773 tree base_binfo;
7779 {
7781 {
7786 }
7787 else
7789 }
7791 /* See if the function member or the whole class type is declared
7792 final and the call can be devirtualized. */
7797 /* [class.mfct.nonstatic]: If a nonstatic member function of a class
7798 X is called for an object that is not of type X, or of a type
7799 derived from X, the behavior is undefined.
7801 So we can assume that anything passed as 'this' is non-null, and
7802 optimize accordingly. */
7804 /* Convert to the base in which the function was declared. */
7807 arg,
7810 /* Check that the base class is accessible. */
7813 {
7818 else
7820 }
7821 /* If fn was found by a using declaration, the conversion path
7822 will be to the derived class, not the base declaring fn. We
7823 must convert from derived to base. */
7834 else
7838 }
7843 {
7850 /* If the argument is NULL and used to (implicitly) instantiate a
7851 template function (and bind one of the template arguments to
7852 the type of 'long int'), we don't want to warn about passing NULL
7853 to non-pointer argument.
7854 For example, if we have this template function:
7856 template<typename T> void func(T x) {}
7858 we want to warn (when -Wconversion is enabled) in this case:
7860 void foo() {
7861 func<int>(NULL);
7862 }
7864 but not in this case:
7866 void foo() {
7867 func(NULL);
7868 }
7869 */
7876 /* Warn about initializer_list deduction that isn't currently in the
7877 working draft. */
7879 && flag_deduce_init_list
7883 {
7896 {
7904 }
7905 }
7907 /* Set user_conv_p on the argument conversions, so rvalue/base handling
7908 knows not to allow any more UDCs. This needs to happen after we
7909 process cand->warnings. */
7918 arg_complain);
7923 else
7925 }
7927 /* Default arguments */
7929 {
7935 complain);
7939 }
7941 /* Ellipsis */
7944 {
7947 {
7948 /* Do no conversions for certain magic varargs. */
7952 }
7954 /* For other magic varargs only do decay_conversion. */
7959 {
7960 /* Avoid infinite recursion trying to call A(...). */
7962 /* Try to call the actual copy constructor for a good error. */
7965 }
7966 else
7971 }
7976 /* Avoid to do argument-transformation, if warnings for format, and for
7977 nonnull are disabled. Just in case that at least one of them is active
7978 the check_function_arguments function might warn about something. */
7982 || warn_format
7983 || warn_suggest_attribute_format
7985 {
7993 }
7996 {
7997 /* Check for passing ellipsis arguments to an inherited constructor. We
7998 could handle this by open-coding the inherited constructor rather than
7999 defining it, but let's not bother now. */
8003 {
8005 {
8009 }
8011 }
8013 /* A base constructor inheriting from a virtual base doesn't get the
8014 inherited arguments, just this and __vtt. */
8017 }
8019 /* Avoid actually calling copy constructors and copy assignment operators,
8020 if possible. */
8027 /* It's unsafe to elide the constructor when handling
8028 a noexcept-expression, it may evaluate to the wrong
8029 value (c++/53025). */
8031 {
8032 tree targ;
8034 tree fa;
8037 /* Pull out the real argument, disregarding const-correctness. */
8039 /* Strip the reference binding for the constructor parameter. */
8043 /* But don't strip any other reference bindings; binding a temporary to a
8044 reference prevents copy elision. */
8050 {
8055 }
8056 else
8061 else
8064 /* In C++17 we shouldn't be copying a TARGET_EXPR except into a base
8065 subobject. */
8068 /* It's from binding the ref parm to a packed field. */
8071 /* See unsafe_copy_elision_p. */
8074 /* [class.copy]: the copy constructor is implicitly defined even if
8075 the implementation elided its use. */
8077 {
8081 }
8083 /* If we're creating a temp and we already have one, don't create a
8084 new one. If we're not creating a temp but we get one, use
8085 INIT_EXPR to collapse the temp into our target. Otherwise, if the
8086 ctor is trivial, do a bitwise copy with a simple TARGET_EXPR for a
8087 temp or an INIT_EXPR otherwise. */
8090 {
8095 }
8098 {
8103 }
8104 }
8109 {
8110 tree to = cp_stabilize_reference
8117 {
8118 /* Avoid copying empty classes. */
8121 }
8123 {
8126 /* Handle NSDMI that refer to the object being initialized. */
8128 }
8129 else
8130 {
8131 /* We must only copy the non-tail padding parts. */
8139 build_index_type
8148 }
8151 }
8154 {
8158 {
8161 no_cleanup_complain);
8162 else
8164 }
8165 }
8167 /* For calls to a multi-versioned function, overload resolution
8168 returns the function with the highest target priority, that is,
8169 the version that will checked for dispatching first. If this
8170 version is inlinable, a direct call to this version can be made
8171 otherwise the call should go through the dispatcher. */
8176 {
8182 }
8188 /* Warn if the built-in writes to an object of a non-trivial type. */
8195 /* Don't mess with virtual lookup in instantiate_non_dependent_expr;
8196 virtual functions can't be constexpr. */
8198 {
8199 tree t;
8206 complain);
8212 }
8213 else
8214 {
8218 }
8224 {
8226 /* build_new_op_1 will clear this when appropriate. */
8228 }
8230 {
8234 }
8236 }
8238 /* Return the DECL of the first non-public data member of class TYPE
8239 or null if none can be found. */
8241 static tree
8243 {
8248 {
8255 }
8261 {
8266 }
8269 }
8271 /* Return true if all copy and move assignment operator overloads for
8272 class TYPE are trivial and at least one of them is not deleted and,
8273 when ACCESS is set, accessible. Return false otherwise. Set
8274 HASASSIGN to true when the TYPE has a (not necessarily trivial)
8275 copy or move assignment. */
8277 static bool
8279 {
8283 /* Iterate over overloads of the assignment operator, checking
8284 accessible copy assignments for triviality. */
8287 {
8290 /* Skip operators that aren't copy assignments. */
8297 /* Skip template assignment operators and deleted functions. */
8307 /* Break early when both properties have been determined. */
8310 }
8312 /* Return true if they're all trivial and one of the expressions
8313 TYPE() = TYPE() or TYPE() = (TYPE&)() is valid. */
8318 }
8320 /* Return true if all copy and move ctor overloads for class TYPE are
8321 trivial and at least one of them is not deleted and, when ACCESS is
8322 set, accessible. Return false otherwise. Set each element of HASCTOR[]
8323 to true when the TYPE has a (not necessarily trivial) default and copy
8324 (or move) ctor, respectively. */
8326 static bool
8328 {
8333 {
8336 /* Skip template constructors. */
8342 /* Skip ctors other than default, copy, and move. */
8358 /* Break early when both properties have been determined. */
8361 }
8364 }
8366 /* Issue a warning on a call to the built-in function FNDECL if it is
8367 a raw memory write whose destination is not an object of (something
8368 like) trivial or standard layout type with a non-deleted assignment
8369 and copy ctor. Detects const correctness violations, corrupting
8370 references, virtual table pointers, and bypassing non-trivial
8371 assignments. */
8373 static void
8376 {
8377 /* Except for bcopy where it's second, the destination pointer is
8378 the first argument for all functions handled here. Compute
8379 the index of the destination and source arguments. */
8389 /* Determine the type of the pointed-to object and whether it's
8390 a complete class type. */
8396 /* Check to see if the raw memory call is made by a ctor or dtor
8397 with this as the destination argument for the destination type.
8398 If so, be more permissive. */
8403 {
8409 /* A ctor and dtor for a class with no bases and no virtual functions
8410 can do whatever they want. Bail early with no further checking. */
8413 }
8415 /* True if the class is trivial. */
8418 /* Set to true if DESTYPE has an accessible copy assignment. */
8420 /* True if all of the class' overloaded copy assignment operators
8421 are all trivial (and not deleted) and at least one of them is
8422 accessible. */
8425 /* Set to true if DESTTYPE has an accessible default and copy ctor,
8426 respectively. */
8429 /* True if all of the class' overloaded copy constructors are all
8430 trivial (and not deleted) and at least one of them is accessible. */
8433 /* Set FLD to the first private/protected member of the class. */
8436 /* The warning format string. */
8438 /* A suggested alternative to offer instead of the raw memory call.
8439 Empty string when none can be come up with. */
8444 {
8447 {
8448 /* Diagnose setting non-copy-assignable or non-trivial types,
8449 or types with a private member, to (potentially) non-zero
8450 bytes. Since the value of the bytes being written is unknown,
8451 suggest using assignment instead (if one exists). Also warn
8452 for writes into objects for which zero-initialization doesn't
8453 mean all bits clear (pointer-to-member data, where null is all
8454 bits set). Since the value being written is (most likely)
8455 non-zero, simply suggest assignment (but not copy assignment). */
8463 {
8466 "%qD writing to an object of type %#qT with "
8469 }
8475 }
8476 /* Fall through. */
8479 /* Similarly to the above, diagnose clearing non-trivial or non-
8480 standard layout objects, or objects of types with no assignmenmt.
8481 Since the value being written is known to be zero, suggest either
8482 copy assignment, copy ctor, or default ctor as an alternative,
8483 depending on what's available. */
8506 /* Determine the type of the source object. */
8510 else
8513 /* Since it's impossible to determine wheter the byte copy is
8514 being used in place of assignment to an existing object or
8515 as a substitute for initialization, assume it's the former.
8516 Determine the best alternative to use instead depending on
8517 what's not deleted. */
8538 srctype))
8539 {
8540 /* Warn when copying into a non-trivial object from an object
8541 of a different type other than void or char. */
8543 "%qD copying an object of non-trivial type "
8546 }
8551 srctype))
8552 {
8555 "%qD copying an object of type %#qT with "
8556 "%qs member %qD from an array of %#qT; use "
8559 }
8561 {
8566 /* Finally, warn on partial copies. */
8567 unsigned HOST_WIDE_INT typesize
8573 "a non-trivial type %#qT leaves %wu "
8576 "a non-trivial type %#qT leaves %wu "
8579 }
8594 {
8598 /* Finally, warn on reallocation into insufficient space. */
8600 "%qD moving an object of non-trivial type "
8603 sz);
8604 }
8609 }
8612 {
8616 else
8619 }
8623 }
8625 /* Build and return a call to FN, using NARGS arguments in ARGARRAY.
8626 This function performs no overload resolution, conversion, or other
8627 high-level operations. */
8629 tree
8631 tsubst_flags_t complain)
8632 {
8633 tree fndecl;
8635 /* Remember roughly where this call is. */
8642 /* Check that arguments to builtin functions match the expectations. */
8646 {
8649 /* We need to take care that values to BUILT_IN_NORMAL
8650 are reduced. */
8657 }
8662 /* 5.2.2/11: If a function call is a prvalue of object type: if the
8663 function call is either the operand of a decltype-specifier or the
8664 right operand of a comma operator that is the operand of a
8665 decltype-specifier, a temporary object is not introduced for the
8666 prvalue. The type of the prvalue may be incomplete. */
8668 {
8674 {
8677 }
8678 }
8680 }
8682 /* Returns the value to use for the in-charge parameter when making a
8683 call to a function with the indicated NAME.
8685 FIXME:Can't we find a neater way to do this mapping? */
8687 tree
8689 {
8691 {
8695 }
8696 else
8697 {
8703 }
8706 }
8708 /* We've built up a constructor call RET. Complain if it delegates to the
8709 constructor we're currently compiling. */
8711 static void
8713 {
8719 }
8721 /* Build a call to a constructor, destructor, or an assignment
8722 operator for INSTANCE, an expression with class type. NAME
8723 indicates the special member function to call; *ARGS are the
8724 arguments. ARGS may be NULL. This may change ARGS. BINFO
8725 indicates the base of INSTANCE that is to be passed as the `this'
8726 parameter to the member function called.
8728 FLAGS are the LOOKUP_* flags to use when processing the call.
8730 If NAME indicates a complete object constructor, INSTANCE may be
8731 NULL_TREE. In this case, the caller will call build_cplus_new to
8732 store the newly constructed object into a VAR_DECL. */
8734 tree
8737 {
8738 tree fns;
8739 /* The type of the subobject to be constructed or destroyed. */
8740 tree class_type;
8742 tree ret;
8746 {
8747 /* Resolve the name. */
8752 }
8758 /* Handle the special case where INSTANCE is NULL_TREE. */
8761 else
8762 {
8766 /* Convert to the base class, if necessary. */
8769 {
8771 /* For constructors and destructors, either the base is
8772 non-virtual, or it is virtual but we are doing the
8773 conversion from a constructor or destructor for the
8774 complete object. In either case, we can convert
8775 statically. */
8777 else
8778 {
8779 /* However, for assignment operators, we must convert
8780 dynamically if the base is virtual. */
8784 }
8785 }
8786 }
8790 /* In C++17, "If the initializer expression is a prvalue and the
8791 cv-unqualified version of the source type is the same class as the class
8792 of the destination, the initializer expression is used to initialize the
8793 destination object." Handle that here to avoid doing overload
8794 resolution. */
8798 {
8801 /* FIXME P0135 doesn't say how to handle direct initialization from a
8802 type with a suitable conversion operator. Let's handle it like
8803 copy-initialization, but allowing explict conversions. */
8806 /* If we're using this to initialize a non-temporary object, don't
8807 require the destructor to be accessible. */
8811 sub_complain,
8812 flags);
8815 && (same_type_ignoring_top_level_qualifiers_p
8817 {
8823 /* Avoid change of behavior on Wunused-var-2.C. */
8826 }
8827 }
8831 /* When making a call to a constructor or destructor for a subobject
8832 that uses virtual base classes, pass down a pointer to a VTT for
8833 the subobject. */
8837 {
8838 tree vtt;
8839 tree sub_vtt;
8841 /* If the current function is a complete object constructor
8842 or destructor, then we fetch the VTT directly.
8843 Otherwise, we look it up using the VTT we were given. */
8851 else
8855 {
8858 }
8861 }
8866 complain);
8877 }
8879 /* Return the NAME, as a C string. The NAME indicates a function that
8880 is a member of TYPE. *FREE_P is set to true if the caller must
8881 free the memory returned.
8883 Rather than go through all of this, we should simply set the names
8884 of constructors and destructors appropriately, and dispense with
8885 ctor_identifier, dtor_identifier, etc. */
8889 {
8892 /* Assume that we will not allocate memory. */
8894 /* Constructors and destructors are special. */
8896 {
8897 pretty_name
8899 /* For a destructor, add the '~'. */
8901 {
8903 /* Remember that we need to free the memory allocated. */
8905 }
8906 }
8908 {
8911 TFF_PLAIN_IDENTIFIER),
8912 NULL);
8913 /* Remember that we need to free the memory allocated. */
8915 }
8916 else
8920 }
8922 /* Build a call to "INSTANCE.FN (ARGS)". If FN_P is non-NULL, it will
8923 be set, upon return, to the function called. ARGS may be NULL.
8924 This may change ARGS. */
8926 static tree
8930 {
8935 tree optype;
8937 tree name;
8940 tree call;
8941 tree fn;
8944 tree orig_instance;
8945 tree orig_fns;
8951 /* We don't know what function we're going to call, yet. */
8960 {
8964 }
8969 /* Dismantle the baselink to collect all the information we need. */
8977 {
8981 }
8992 {
8997 }
9000 /* Under DR 147 A::A() is an invalid constructor call,
9001 not a functional cast. */
9003 {
9015 complain);
9017 }
9019 /* Process the argument list. */
9021 {
9025 }
9027 /* Consider the object argument to be used even if we end up selecting a
9028 static member function. */
9031 /* Figure out whether to skip the first argument for the error
9032 message we will display to users if an error occurs. We don't
9033 want to display any compiler-generated arguments. The "this"
9034 pointer hasn't been added yet. However, we must remove the VTT
9035 pointer if this is a call to a base-class constructor or
9036 destructor. */
9039 {
9040 /* Callers should explicitly indicate whether they want to ctor
9041 the complete object or just the part without virtual bases. */
9044 /* Remove the VTT pointer, if present. */
9049 /* It's OK to call destructors and constructors on cv-qualified
9050 objects. Therefore, convert the INSTANCE to the unqualified
9051 type, if necessary. */
9053 {
9057 }
9058 }
9059 else
9062 /* For the overload resolution we need to find the actual `this`
9063 that would be captured if the call turns out to be to a
9064 non-static member function. Do not actually capture it at this
9065 point. */
9067 /* Constructors don't use the enclosing 'this'. */
9069 else
9072 /* Get the high-water mark for the CONVERSION_OBSTACK. */
9075 /* The number of arguments artificial parms in ARGS; we subtract one because
9076 there's no 'this' in ARGS. */
9079 /* If CONSTRUCTOR_IS_DIRECT_INIT is set, this was a T{ } form
9080 initializer, not T({ }). */
9084 {
9091 /* If the initializer list has no elements and T is a class type with
9092 a default constructor, the object is value-initialized. Handle
9093 this here so we don't need to handle it wherever we use
9094 build_special_member_call. */
9097 /* For a user-provided default constructor, use the normal
9098 mechanisms so that protected access works. */
9103 /* If BASETYPE is an aggregate, we need to do aggregate
9104 initialization. */
9106 {
9109 }
9112 {
9118 }
9120 /* Otherwise go ahead with overload resolution. */
9125 }
9126 else
9135 {
9137 {
9144 else
9145 {
9150 {
9153 }
9161 }
9163 }
9165 }
9166 else
9167 {
9170 {
9173 tree arglist;
9176 {
9184 else
9190 }
9192 }
9193 else
9194 {
9202 {
9203 /* This is not an error, it is runtime undefined
9204 behavior. */
9213 fn);
9214 }
9219 {
9224 {
9225 /* We captured 'this' in the current lambda now that
9226 we know we really need it. */
9228 }
9230 /* We can't tell until instantiation time whether we can use
9232 else
9233 {
9236 fn);
9238 }
9239 }
9242 {
9243 /* Optimize away vtable lookup if we know that this
9244 function can't be overridden. We need to check if
9245 the context and the type where we found fn are the same,
9246 actually FN might be defined in a different class
9247 type because of a using-declaration. In this case, we
9248 do not want to perform a non-virtual call. */
9250 && same_type_ignoring_top_level_qualifiers_p
9256 /* Now we know what function is being called. */
9259 /* Build the actual CALL_EXPR. */
9261 /* In an expression of the form `a->f()' where `f' turns
9262 out to be a static member function, `a' is
9263 none-the-less evaluated. */
9272 /* An explicit call of the form "x->~X()" has type
9273 "void". However, on platforms where destructors
9274 return "this" (i.e., those where
9275 targetm.cxx.cdtor_returns_this is true), such calls
9276 will appear to have a return value of pointer type
9277 to the low-level call machinery. We do not want to
9278 change the low-level machinery, since we want to be
9279 able to optimize "delete f()" on such platforms as
9280 "operator delete(~X(f()))" (rather than generating
9281 "t = f(), ~X(t), operator delete (t)"). */
9283 }
9284 }
9285 }
9288 {
9294 {
9297 }
9300 call = (build_min_non_dep_call_vec
9304 orig_args));
9309 }
9311 /* Free all the conversions we allocated. */
9318 }
9320 /* Wrapper for above. */
9322 tree
9326 {
9327 tree ret;
9333 }
9335 /* Returns true iff standard conversion sequence ICS1 is a proper
9336 subsequence of ICS2. */
9338 static bool
9340 {
9341 /* We can assume that a conversion of the same code
9342 between the same types indicates a subsequence since we only get
9343 here if the types we are converting from are the same. */
9350 {
9360 /* At this point, ICS1 cannot be a proper subsequence of
9361 ICS2. We can get a USER_CONV when we are comparing the
9362 second standard conversion sequence of two user conversion
9363 sequences. */
9378 }
9379 }
9381 /* Returns nonzero iff DERIVED is derived from BASE. The inputs may
9382 be any _TYPE nodes. */
9384 bool
9386 {
9390 /* We only allow proper derivation here. The DERIVED_FROM_P macro
9391 considers every class derived from itself. */
9394 }
9396 /* We build the ICS for an implicit object parameter as a pointer
9397 conversion sequence. However, such a sequence should be compared
9398 as if it were a reference conversion sequence. If ICS is the
9399 implicit conversion sequence for an implicit object parameter,
9400 modify it accordingly. */
9402 static void
9404 {
9406 {
9407 /* [over.match.funcs]
9409 For non-static member functions, the type of the
9410 implicit object parameter is "reference to cv X"
9411 where X is the class of which the function is a
9412 member and cv is the cv-qualification on the member
9413 function declaration. */
9415 tree reference_type;
9417 /* The `this' parameter is a pointer to a class type. Make the
9418 implicit conversion talk about a reference to that same class
9419 type. */
9432 }
9433 }
9435 /* If *ICS is a REF_BIND set *ICS to the remainder of the conversion,
9436 and return the initial reference binding conversion. Otherwise,
9437 leave *ICS unchanged and return NULL. */
9441 {
9443 {
9448 }
9451 }
9453 /* Compare two implicit conversion sequences according to the rules set out in
9454 [over.ics.rank]. Return values:
9456 1: ics1 is better than ics2
9457 -1: ics2 is better than ics1
9458 0: ics1 and ics2 are indistinguishable */
9460 static int
9462 {
9463 tree from_type1;
9464 tree from_type2;
9465 tree to_type1;
9466 tree to_type2;
9473 /* REF_BINDING is nonzero if the result of the conversion sequence
9474 is a reference type. In that case REF_CONV is the reference
9475 binding conversion. */
9479 /* Compare badness before stripping the reference conversion. */
9485 /* Handle implicit object parameters. */
9489 /* Handle reference parameters. */
9493 /* List-initialization sequence L1 is a better conversion sequence than
9494 list-initialization sequence L2 if L1 converts to
9495 std::initializer_list<X> for some X and L2 does not. */
9501 /* [over.ics.rank]
9503 When comparing the basic forms of implicit conversion sequences (as
9504 defined in _over.best.ics_)
9506 --a standard conversion sequence (_over.ics.scs_) is a better
9507 conversion sequence than a user-defined conversion sequence
9508 or an ellipsis conversion sequence, and
9510 --a user-defined conversion sequence (_over.ics.user_) is a
9511 better conversion sequence than an ellipsis conversion sequence
9512 (_over.ics.ellipsis_). */
9513 /* Use BAD_CONVERSION_RANK because we already checked for a badness
9514 mismatch. If both ICS are bad, we try to make a decision based on
9515 what would have happened if they'd been good. This is not an
9516 extension, we'll still give an error when we build up the call; this
9517 just helps us give a more helpful error message. */
9527 /* Both conversions are ellipsis conversions. */
9530 /* User-defined conversion sequence U1 is a better conversion sequence
9531 than another user-defined conversion sequence U2 if they contain the
9532 same user-defined conversion operator or constructor and if the sec-
9533 ond standard conversion sequence of U1 is better than the second
9534 standard conversion sequence of U2. */
9536 /* Handle list-conversion with the same code even though it isn't always
9537 ranked as a user-defined conversion and it doesn't have a second
9538 standard conversion sequence; it will still have the desired effect.
9539 Specifically, we need to do the reference binding comparison at the
9540 end of this function. */
9543 {
9559 {
9564 }
9565 else
9566 {
9567 /* For ambiguous or aggregate conversions, use the target type as
9568 a proxy for the conversion function. */
9571 }
9573 /* We can just fall through here, after setting up
9574 FROM_TYPE1 and FROM_TYPE2. */
9577 }
9578 else
9579 {
9583 /* We're dealing with two standard conversion sequences.
9585 [over.ics.rank]
9587 Standard conversion sequence S1 is a better conversion
9588 sequence than standard conversion sequence S2 if
9590 --S1 is a proper subsequence of S2 (comparing the conversion
9591 sequences in the canonical form defined by _over.ics.scs_,
9592 excluding any Lvalue Transformation; the identity
9593 conversion sequence is considered to be a subsequence of
9594 any non-identity conversion sequence */
9605 }
9607 /* One sequence can only be a subsequence of the other if they start with
9608 the same type. They can start with different types when comparing the
9609 second standard conversion sequence in two user-defined conversion
9610 sequences. */
9612 {
9617 }
9619 /* [over.ics.rank]
9621 Or, if not that,
9623 --the rank of S1 is better than the rank of S2 (by the rules
9624 defined below):
9626 Standard conversion sequences are ordered by their ranks: an Exact
9627 Match is a better conversion than a Promotion, which is a better
9628 conversion than a Conversion.
9630 Two conversion sequences with the same rank are indistinguishable
9631 unless one of the following rules applies:
9633 --A conversion that does not a convert a pointer, pointer to member,
9634 or std::nullptr_t to bool is better than one that does.
9636 The ICS_STD_RANK automatically handles the pointer-to-bool rule,
9637 so that we do not have to check it explicitly. */
9646 /* A conversion from scalar arithmetic type to complex is worse than a
9647 conversion between scalar arithmetic types. */
9654 {
9657 else
9659 }
9665 {
9670 }
9671 /* The rules for pointers to members A::* are just like the rules
9672 for pointers A*, except opposite: if B is derived from A then
9673 A::* converts to B::*, not vice versa. For that reason, we
9674 switch the from_ and to_ variables here. */
9681 {
9686 }
9691 {
9692 /* This was one of the pointer or pointer-like conversions.
9694 [over.ics.rank]
9696 --If class B is derived directly or indirectly from class A,
9697 conversion of B* to A* is better than conversion of B* to
9698 void*, and conversion of A* to void* is better than
9699 conversion of B* to void*. */
9702 {
9704 deref_from_type2))
9707 deref_from_type1))
9709 }
9712 {
9714 {
9716 {
9718 deref_to_type1))
9720 }
9721 /* We know that DEREF_TO_TYPE1 is `void' here. */
9723 deref_to_type2))
9725 }
9726 }
9729 {
9730 /* [over.ics.rank]
9732 --If class B is derived directly or indirectly from class A
9733 and class C is derived directly or indirectly from B,
9735 --conversion of C* to B* is better than conversion of C* to
9736 A*,
9738 --conversion of B* to A* is better than conversion of C* to
9739 A* */
9741 {
9743 deref_to_type2))
9746 deref_to_type1))
9748 }
9750 {
9752 deref_from_type1))
9755 deref_from_type2))
9757 }
9758 }
9759 }
9762 {
9765 /* [over.ics.rank]
9767 --binding of an expression of type C to a reference of type
9768 B& is better than binding an expression of type C to a
9769 reference of type A&
9771 --conversion of C to B is better than conversion of C to A, */
9774 {
9779 }
9780 }
9783 {
9786 /* [over.ics.rank]
9788 --binding of an expression of type B to a reference of type
9789 A& is better than binding an expression of type C to a
9790 reference of type A&,
9792 --conversion of B to A is better than conversion of C to A */
9795 {
9800 }
9801 }
9803 /* [over.ics.rank]
9805 --S1 and S2 differ only in their qualification conversion and yield
9806 similar types T1 and T2 (_conv.qual_), respectively, and the cv-
9807 qualification signature of type T1 is a proper subset of the cv-
9808 qualification signature of type T2 */
9812 {
9816 }
9818 /* [over.ics.rank]
9820 --S1 and S2 are reference bindings (_dcl.init.ref_) and neither refers
9821 to an implicit object parameter of a non-static member function
9822 declared without a ref-qualifier, and either S1 binds an lvalue
9823 reference to an lvalue and S2 binds an rvalue reference or S1 binds an
9824 rvalue reference to an rvalue and S2 binds an lvalue reference (C++0x
9825 draft standard, 13.3.3.2)
9827 --S1 and S2 are reference bindings (_dcl.init.ref_), and the
9828 types to which the references refer are the same type except for
9829 top-level cv-qualifiers, and the type to which the reference
9830 initialized by S2 refers is more cv-qualified than the type to
9831 which the reference initialized by S1 refers.
9833 DR 1328 [over.match.best]: the context is an initialization by
9834 conversion function for direct reference binding (13.3.1.6) of a
9835 reference to function type, the return type of F1 is the same kind of
9836 reference (i.e. lvalue or rvalue) as the reference being initialized,
9837 and the return type of F2 is not. */
9840 {
9847 {
9851 /* Don't prefer a bad conversion that drops cv-quals to a bad
9852 conversion with the wrong rvalueness. */
9856 }
9859 {
9863 {
9864 /* Prefer the one that drops fewer cv-quals. */
9869 }
9871 }
9872 }
9874 /* Neither conversion sequence is better than the other. */
9876 }
9878 /* The source type for this standard conversion sequence. */
9880 static tree
9882 {
9884 {
9889 }
9891 }
9893 /* Note a warning about preferring WINNER to LOSER. We do this by storing
9894 a pointer to LOSER and re-running joust to produce the warning if WINNER
9895 is actually used. */
9897 static void
9899 {
9905 }
9907 /* Compare two candidates for overloading as described in
9908 [over.match.best]. Return values:
9910 1: cand1 is better than cand2
9911 -1: cand2 is better than cand1
9912 0: cand1 and cand2 are indistinguishable */
9914 static int
9916 tsubst_flags_t complain)
9917 {
9923 /* Candidates that involve bad conversions are always worse than those
9924 that don't. */
9930 /* If we have two pseudo-candidates for conversions to the same type,
9931 or two candidates for the same function, arbitrarily pick one. */
9936 /* Prefer a non-deleted function over an implicitly deleted move
9937 constructor or assignment operator. This differs slightly from the
9938 wording for issue 1402 (which says the move op is ignored by overload
9939 resolution), but this way produces better error messages. */
9943 {
9950 }
9952 /* a viable function F1
9953 is defined to be a better function than another viable function F2 if
9954 for all arguments i, ICSi(F1) is not a worse conversion sequence than
9955 ICSi(F2), and then */
9957 /* for some argument j, ICSj(F1) is a better conversion sequence than
9958 ICSj(F2) */
9960 /* For comparing static and non-static member functions, we ignore
9961 the implicit object parameter of the non-static function. The
9962 standard says to pretend that the static function has an object
9963 parm, but that won't work with operator overloading. */
9966 {
9972 /* We're comparing a near-match list constructor and a near-match
9973 non-list constructor. Just treat them as unordered. */
9980 else
9981 {
9984 }
9985 }
9988 {
9994 {
9996 && warn_sign_promo
10008 {
10015 else
10020 {
10024 }
10025 else
10027 }
10030 {
10033 }
10035 }
10036 }
10038 /* warn about confusing overload resolution for user-defined conversions,
10039 either between a constructor and a conversion op, or between two
10040 conversion ops. */
10045 {
10051 else
10054 /* We don't want to complain about `X::operator T1 ()'
10055 beating `X::operator T2 () const', when T2 is a no less
10056 cv-qualified version of T1. */
10059 {
10064 {
10067 }
10070 }
10071 else
10077 {
10084 {
10086 }
10087 }
10088 else
10090 }
10095 /* DR 495 moved this tiebreaker above the template ones. */
10096 /* or, if not that,
10097 the context is an initialization by user-defined conversion (see
10098 _dcl.init_ and _over.match.user_) and the standard conversion
10099 sequence from the return type of F1 to the destination type (i.e.,
10100 the type of the entity being initialized) is a better conversion
10101 sequence than the standard conversion sequence from the return type
10102 of F2 to the destination type. */
10105 {
10109 }
10111 /* or, if not that,
10112 F1 is a non-template function and F2 is a template function
10113 specialization. */
10120 /* or, if not that,
10121 F1 and F2 are template functions and the function template for F1 is
10122 more specialized than the template for F2 according to the partial
10123 ordering rules. */
10126 {
10127 winner = more_specialized_fn
10130 /* [temp.func.order]: The presence of unused ellipsis and default
10131 arguments has no effect on the partial ordering of function
10132 templates. add_function_candidate() will not have
10133 counted the "this" argument for constructors. */
10137 }
10139 // C++ Concepts
10140 // or, if not that, F1 is more constrained than F2.
10142 {
10146 }
10148 /* F1 is generated from a deduction-guide (13.3.1.8) and F2 is not */
10150 {
10152 /* We distinguish between candidates from an explicit deduction guide and
10153 candidates built from a constructor based on DECL_ARTIFICIAL. */
10160 {
10161 /* Prefer the special copy guide over a declared copy/move
10162 constructor. */
10168 /* Prefer a candidate generated from a non-template constructor. */
10173 }
10174 }
10176 /* F1 is a member of a class D, F2 is a member of a base class B of D, and
10177 for all arguments the corresponding parameters of F1 and F2 have the same
10178 type (CWG 2273/2277). */
10183 {
10197 {
10199 {
10204 }
10207 }
10208 }
10210 /* Check whether we can discard a builtin candidate, either because we
10211 have two identical ones or matching builtin and non-builtin candidates.
10213 (Pedantically in the latter case the builtin which matched the user
10214 function should not be added to the overload set, but we spot it here.
10216 [over.match.oper]
10217 ... the builtin candidates include ...
10218 - do not have the same parameter type list as any non-template
10219 non-member candidate. */
10222 {
10228 {
10230 /* Two built-in candidates; arbitrarily pick one. */
10233 /* cand1 is built-in; prefer cand2. */
10235 else
10236 /* cand2 is built-in; prefer cand1. */
10238 }
10239 }
10241 /* For candidates of a multi-versioned function, make the version with
10242 the highest priority win. This version will be checked for dispatching
10243 first. If this version can be inlined into the caller, the front-end
10244 will simply make a direct call to this function. */
10250 {
10256 /* Check if cand1->fn and cand2->fn are versions of the same function. It
10257 is possible that cand1->fn and cand2->fn are function versions but of
10258 different functions. Check types to see if they are versions of the same
10259 function. */
10262 {
10263 /* Always make the version with the higher priority, more
10264 specialized, win. */
10268 else
10270 }
10271 }
10273 /* If the two function declarations represent the same function (this can
10274 happen with declarations in multiple scopes and arg-dependent lookup),
10275 arbitrarily choose one. But first make sure the default args we're
10276 using match. */
10279 {
10286 {
10287 /* Don't crash if the fn is variadic. */
10292 }
10300 {
10303 {
10305 {
10307 {
10309 "default argument mismatch in "
10311 {
10316 }
10317 }
10318 else
10320 }
10321 else
10324 }
10327 }
10330 }
10332 tweak:
10334 /* Extension: If the worst conversion for one candidate is worse than the
10335 worst conversion for the other, take the first. */
10337 {
10342 {
10347 }
10353 {
10354 /* Don't choose a deleted function over ambiguity. */
10358 {
10360 "ISO C++ says that these are ambiguous, even "
10361 "though the worst conversion for the first is better than "
10365 }
10366 else
10369 }
10370 }
10374 }
10376 /* Given a list of candidates for overloading, find the best one, if any.
10377 This algorithm has a worst case of O(2n) (winner is last), and a best
10378 case of O(n/2) (totally ambiguous); much better than a sorting
10379 algorithm. */
10383 {
10388 /* Walk through the list once, comparing each current champ to the next
10389 candidate, knocking out a candidate or two with each comparison. */
10392 {
10396 else
10397 {
10399 {
10404 }
10405 else
10406 {
10409 }
10412 }
10413 }
10415 /* Make sure the champ is better than all the candidates it hasn't yet
10416 been compared to. */
10419 challenger != champ
10422 {
10426 }
10429 }
10431 /* Returns nonzero if things of type FROM can be converted to TO. */
10433 bool
10435 {
10437 /* implicit_conversion only considers user-defined conversions
10438 if it has an expression for the call argument list. */
10442 }
10444 /* Returns nonzero if things of type FROM can be converted to TO with a
10445 standard conversion. */
10447 bool
10449 {
10451 }
10453 /* Returns nonzero if ARG (of type FROM) can be converted to TO. */
10455 bool
10457 tsubst_flags_t complain)
10458 {
10463 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10465 /* We want to discard any access checks done for this test,
10466 as we might not be in the appropriate access context and
10467 we'll do the check again when we actually perform the
10468 conversion. */
10475 /* Discard the access checks now. */
10477 /* Free all the conversions we allocated. */
10481 }
10483 /* Like can_convert_arg, but allows dubious conversions as well. */
10485 bool
10487 tsubst_flags_t complain)
10488 {
10492 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10494 /* Try to perform the conversion. */
10497 /* Free all the conversions we allocated. */
10501 }
10503 /* Convert EXPR to TYPE. Return the converted expression.
10505 Note that we allow bad conversions here because by the time we get to
10506 this point we are committed to doing the conversion. If we end up
10507 doing a bad conversion, convert_like will complain. */
10509 tree
10512 {
10520 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10528 {
10530 {
10531 /* If expr has unknown type, then it is an overloaded function.
10532 Call instantiate_type to get good error messages. */
10537 else
10540 }
10542 }
10544 {
10545 /* In a template, we are only concerned about determining the
10546 type of non-dependent expressions, so we do not have to
10547 perform the actual conversion. But for initializers, we
10548 need to be able to perform it at instantiation
10549 (or instantiate_non_dependent_expr) time. */
10553 }
10554 else
10557 /* Free all the conversions we allocated. */
10561 }
10563 tree
10565 {
10567 LOOKUP_IMPLICIT);
10568 }
10570 /* Convert EXPR to TYPE (as a direct-initialization) if that is
10571 permitted. If the conversion is valid, the converted expression is
10572 returned. Otherwise, NULL_TREE is returned, except in the case
10573 that TYPE is a class type; in that case, an error is issued. If
10574 C_CAST_P is true, then this direct-initialization is taking
10575 place as part of a static_cast being attempted as part of a C-style
10576 cast. */
10578 tree
10580 tree expr,
10582 tsubst_flags_t complain)
10583 {
10589 /* [dcl.init]
10591 If the destination type is a (possibly cv-qualified) class type:
10593 -- If the initialization is direct-initialization ...,
10594 constructors are considered. ... If no constructor applies, or
10595 the overload resolution is ambiguous, the initialization is
10596 ill-formed. */
10598 {
10604 }
10606 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10610 c_cast_p,
10615 {
10616 /* In a template, we are only concerned about determining the
10617 type of non-dependent expressions, so we do not have to
10618 perform the actual conversion. But for initializers, we
10619 need to be able to perform it at instantiation
10620 (or instantiate_non_dependent_expr) time. */
10623 }
10624 else
10627 c_cast_p,
10628 complain);
10630 /* Free all the conversions we allocated. */
10634 }
10636 /* When initializing a reference that lasts longer than a full-expression,
10637 this special rule applies:
10639 [class.temporary]
10641 The temporary to which the reference is bound or the temporary
10642 that is the complete object to which the reference is bound
10643 persists for the lifetime of the reference.
10645 The temporaries created during the evaluation of the expression
10646 initializing the reference, except the temporary to which the
10647 reference is bound, are destroyed at the end of the
10648 full-expression in which they are created.
10650 In that case, we store the converted expression into a new
10651 VAR_DECL in a new scope.
10653 However, we want to be careful not to create temporaries when
10654 they are not required. For example, given:
10656 struct B {};
10657 struct D : public B {};
10658 D f();
10659 const B& b = f();
10661 there is no need to copy the return value from "f"; we can just
10662 extend its lifetime. Similarly, given:
10664 struct S {};
10665 struct T { operator S(); };
10666 T t;
10667 const S& s = t;
10669 we can extend the lifetime of the return value of the conversion
10670 operator.
10672 The next several functions are involved in this lifetime extension. */
10674 /* DECL is a VAR_DECL or FIELD_DECL whose type is a REFERENCE_TYPE. The
10675 reference is being bound to a temporary. Create and return a new
10676 VAR_DECL with the indicated TYPE; this variable will store the value to
10677 which the reference is bound. */
10679 tree
10681 {
10684 /* Register the variable. */
10687 {
10688 /* Namespace-scope or local static; give it a mangled name. */
10689 /* FIXME share comdat with decl? */
10700 }
10701 else
10702 /* Create a new cleanup level if necessary. */
10706 }
10708 /* EXPR is the initializer for a variable DECL of reference or
10709 std::initializer_list type. Create, push and return a new VAR_DECL
10710 for the initializer so that it will live as long as DECL. Any
10711 cleanup for the new variable is returned through CLEANUP, and the
10712 code to initialize the new variable is returned through INITP. */
10714 static tree
10717 {
10718 tree init;
10719 tree type;
10720 tree var;
10722 /* Create the temporary variable. */
10726 /* If the rvalue is the result of a function call it will be
10727 a TARGET_EXPR. If it is some other construct (such as a
10728 member access expression where the underlying object is
10729 itself the result of a function call), turn it into a
10730 TARGET_EXPR here. It is important that EXPR be a
10731 TARGET_EXPR below since otherwise the INIT_EXPR will
10732 attempt to make a bitwise copy of EXPR to initialize
10733 VAR. */
10739 {
10743 }
10745 /* Recursively extend temps in this initializer. */
10749 /* Any reference temp has a non-trivial initializer. */
10752 /* If the initializer is constant, put it in DECL_INITIAL so we get
10753 static initialization and use in constant expressions. */
10756 {
10758 {
10759 /* 5.19 says that a constant expression can include an
10760 lvalue-rvalue conversion applied to "a glvalue of literal type
10761 that refers to a non-volatile temporary object initialized
10762 with a constant expression". Rather than try to communicate
10763 that this VAR_DECL is a temporary, just mark it constexpr.
10765 Currently this is only useful for initializer_list temporaries,
10766 since reference vars can't appear in constant expressions. */
10770 }
10773 }
10774 else
10775 /* Create the INIT_EXPR that will initialize the temporary
10776 variable. */
10779 {
10784 else
10785 {
10789 }
10791 /* We must be careful to destroy the temporary only
10792 after its initialization has taken place. If the
10793 initialization throws an exception, then the
10794 destructor should not be run. We cannot simply
10795 transform INIT into something like:
10797 (INIT, ({ CLEANUP_STMT; }))
10799 because emit_local_var always treats the
10800 initializer as a full-expression. Thus, the
10801 destructor would run too early; it would run at the
10802 end of initializing the reference variable, rather
10803 than at the end of the block enclosing the
10804 reference variable.
10806 The solution is to pass back a cleanup expression
10807 which the caller is responsible for attaching to
10808 the statement tree. */
10809 }
10810 else
10811 {
10814 {
10817 tls_aggregates);
10818 else
10820 static_aggregates);
10821 }
10822 else
10823 /* Check whether the dtor is callable. */
10825 }
10826 /* Avoid -Wunused-variable warning (c++/38958). */
10833 }
10835 /* Convert EXPR to the indicated reference TYPE, in a way suitable for
10836 initializing a variable of that TYPE. */
10838 tree
10841 {
10849 /* Get the high-water mark for the CONVERSION_OBSTACK. */
10855 {
10857 {
10866 else
10870 }
10872 }
10875 /* Perform the conversion. */
10878 /* We gave an error in build_user_type_conversion_1. */
10880 else
10883 /* Free all the conversions we allocated. */
10887 }
10889 /* Subroutine of extend_ref_init_temps. Possibly extend one initializer,
10890 which is bound either to a reference or a std::initializer_list. */
10892 static tree
10894 {
10899 {
10903 }
10906 /* Deal with binding to a subobject. */
10910 {
10918 }
10920 }
10922 /* INIT is part of the initializer for DECL. If there are any
10923 reference or initializer lists being initialized, extend their
10924 lifetime to match that of DECL. */
10926 tree
10928 {
10934 else
10935 {
10940 {
10942 {
10943 /* The temporary array underlying a std::initializer_list
10944 is handled like a reference temporary. */
10948 }
10949 else
10950 {
10956 }
10960 }
10961 }
10964 }
10966 /* Returns true iff an initializer for TYPE could contain temporaries that
10967 need to be extended because they are bound to references or
10968 std::initializer_list. */
10970 bool
10972 {
10977 {
10984 }
10986 }
10988 /* Returns true iff TYPE is some variant of std::initializer_list. */
10990 bool
10992 {
10997 /* Look through typedefs. */
11002 }
11004 /* Returns true iff DECL is a list constructor: i.e. a constructor which
11005 will accept an argument list of a single std::initializer_list<T>. */
11007 bool
11009 {
11011 tree arg;
11023 /* There are more non-defaulted parms. */
11027 }