| blob | f60c59260fd8b72b04eeef1ddd3ef50cd153a392 |
1 /* Functions related to invoking methods and overloaded functions.
2 Copyright (C) 1987, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 Free Software Foundation, Inc.
5 Contributed by Michael Tiemann (tiemann@cygnus.com) and
6 modified by Brendan Kehoe (brendan@cygnus.com).
8 This file is part of GCC.
10 GCC is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2, or (at your option)
13 any later version.
15 GCC is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with GCC; see the file COPYING. If not, write to
22 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
23 Boston, MA 02110-1301, USA. */
26 /* High-level class interface. */
45 /* The various kinds of conversion. */
48 ck_identity,
49 ck_lvalue,
50 ck_qual,
51 ck_std,
52 ck_ptr,
53 ck_pmem,
54 ck_base,
55 ck_ref_bind,
56 ck_user,
57 ck_ambig,
58 ck_rvalue
61 /* The rank of the conversion. Order of the enumerals matters; better
62 conversions should come earlier in the list. */
65 cr_identity,
66 cr_exact,
67 cr_promotion,
68 cr_std,
69 cr_pbool,
70 cr_user,
71 cr_ellipsis,
72 cr_bad
75 /* An implicit conversion sequence, in the sense of [over.best.ics].
76 The first conversion to be performed is at the end of the chain.
77 That conversion is always a cr_identity conversion. */
81 /* The kind of conversion represented by this step. */
82 conversion_kind kind;
83 /* The rank of this conversion. */
84 conversion_rank rank;
89 /* If KIND is ck_ref_bind ck_base_conv, true to indicate that a
90 temporary should be created to hold the result of the
91 conversion. */
93 /* If KIND is ck_identity or ck_base_conv, true to indicate that the
94 copy constructor must be accessible, even though it is not being
95 used. */
97 /* If KIND is ck_ptr or ck_pmem, true to indicate that a conversion
98 from a pointer-to-derived to pointer-to-base is being performed. */
100 /* The type of the expression resulting from the conversion. */
101 tree type;
103 /* The next conversion in the chain. Since the conversions are
104 arranged from outermost to innermost, the NEXT conversion will
105 actually be performed before this conversion. This variant is
106 used only when KIND is neither ck_identity nor ck_ambig. */
108 /* The expression at the beginning of the conversion chain. This
109 variant is used only if KIND is ck_identity or ck_ambig. */
110 tree expr;
112 /* The function candidate corresponding to this conversion
113 sequence. This field is only used if KIND is ck_user. */
115 };
117 #define CONVERSION_RANK(NODE) \
118 ((NODE)->bad_p ? cr_bad \
119 : (NODE)->ellipsis_p ? cr_ellipsis \
120 : (NODE)->user_conv_p ? cr_user \
121 : (NODE)->rank)
132 #define convert_like(CONV, EXPR) \
133 convert_like_real ((CONV), (EXPR), NULL_TREE, 0, 0, \
136 #define convert_like_with_context(CONV, EXPR, FN, ARGNO) \
137 convert_like_real ((CONV), (EXPR), (FN), (ARGNO), 0, \
160 static void add_builtin_candidates
163 static void add_builtin_candidate
167 static void build_builtin_candidate
203 /* Returns nonzero iff the destructor name specified in NAME matches BASETYPE.
204 NAME can take many forms... */
206 bool
208 {
209 /* Just accept something we've already complained about. */
218 {
223 else
225 }
226 else
227 {
228 /* In the case of:
230 template <class T> struct S { ~S(); };
231 int i;
232 i.~S();
234 NAME will be a class template. */
237 }
242 }
244 /* We want the address of a function or method. We avoid creating a
245 pointer-to-member function. */
247 tree
249 {
252 /* We have to do these by hand to avoid real pointer to member
253 functions. */
255 {
257 {
261 }
263 }
264 else
268 }
270 /* Build a CALL_EXPR, we can handle FUNCTION_TYPEs, METHOD_TYPEs, or
271 POINTER_TYPE to those. Note, pointer to member function types
272 (TYPE_PTRMEMFUNC_P) must be handled by our callers. */
274 tree
276 {
279 tree tmp;
280 tree decl;
281 tree result_type;
282 tree fntype;
294 {
297 {
298 /* We invoke build_call directly for several library
299 functions. These may have been declared normally if
300 we're building libgcc, so we can't just check
301 DECL_ARTIFICIAL. */
306 }
307 }
308 else
311 /* We check both the decl and the type; a function may be known not to
312 throw without being declared throw(). */
326 /* Don't pass empty class objects by value. This is useful
327 for tags in STL, which are used to control overload resolution.
328 We don't need to handle other cases of copying empty classes. */
333 {
337 }
344 }
346 /* Build something of the form ptr->method (args)
347 or object.method (args). This can also build
348 calls to constructors, and find friends.
350 Member functions always take their class variable
351 as a pointer.
353 INSTANCE is a class instance.
355 NAME is the name of the method desired, usually an IDENTIFIER_NODE.
357 PARMS help to figure out what that NAME really refers to.
359 BASETYPE_PATH, if non-NULL, contains a chain from the type of INSTANCE
360 down to the real instance type to use for access checking. We need this
361 information to get protected accesses correct.
363 FLAGS is the logical disjunction of zero or more LOOKUP_
364 flags. See cp-tree.h for more info.
366 If this is all OK, calls build_function_call with the resolved
367 member function.
369 This function must also handle being called to perform
370 initialization, promotion/coercion of arguments, and
371 instantiation of default parameters.
373 Note that NAME may refer to an instance variable name. If
374 `operator()()' is defined for the type of that field, then we return
375 that result. */
377 /* New overloading code. */
385 };
388 /* The FUNCTION_DECL that will be called if this candidate is
389 selected by overload resolution. */
390 tree fn;
391 /* The arguments to use when calling this function. */
392 tree args;
393 /* The implicit conversion sequences for each of the arguments to
394 FN. */
396 /* The number of implicit conversion sequences. */
398 /* If FN is a user-defined conversion, the standard conversion
399 sequence from the type returned by FN to the desired destination
400 type. */
403 /* If FN is a member function, the binfo indicating the path used to
404 qualify the name of FN at the call site. This path is used to
405 determine whether or not FN is accessible if it is selected by
406 overload resolution. The DECL_CONTEXT of FN will always be a
407 (possibly improper) base of this binfo. */
408 tree access_path;
409 /* If FN is a non-static member function, the binfo indicating the
410 subobject to which the `this' pointer should be converted if FN
411 is selected by overload resolution. The type pointed to the by
412 the `this' pointer must correspond to the most derived class
413 indicated by the CONVERSION_PATH. */
414 tree conversion_path;
415 tree template_decl;
418 };
420 /* Returns true iff T is a null pointer constant in the sense of
421 [conv.ptr]. */
423 bool
425 {
426 /* [conv.ptr]
428 A null pointer constant is an integral constant expression
429 (_expr.const_) rvalue of integer type that evaluates to zero. */
434 {
438 }
440 }
442 /* Returns nonzero if PARMLIST consists of only default parms and/or
443 ellipsis. */
445 bool
447 {
453 }
455 /* Allocate N bytes of memory from the conversion obstack. The memory
456 is zeroed before being returned. */
460 {
463 {
466 }
470 }
472 /* Dynamically allocate a conversion. */
476 {
481 }
483 #ifdef ENABLE_CHECKING
485 /* Make sure that all memory on the conversion obstack has been
486 freed. */
488 void
490 {
494 }
498 /* Dynamically allocate an array of N conversions. */
502 {
504 }
508 {
512 /* We can't use buildl1 here because CODE could be USER_CONV, which
513 takes two arguments. In that case, the caller is responsible for
514 filling in the second argument. */
520 {
536 }
542 }
544 /* Build a representation of the identity conversion from EXPR to
545 itself. The TYPE should match the type of EXPR, if EXPR is non-NULL. */
549 {
557 }
559 /* Converting from EXPR to TYPE was ambiguous in the sense that there
560 were multiple user-defined conversions to accomplish the job.
561 Build a conversion that indicates that ambiguity. */
565 {
573 }
575 tree
577 {
581 }
583 /* Returns the standard conversion path (see [conv]) from type FROM to type
584 TO, if any. For proper handling of null pointer constants, you must
585 also pass the expression EXPR to convert from. If C_CAST_P is true,
586 this conversion is coming from a C-style cast. */
591 {
598 {
601 }
607 {
612 }
619 {
623 }
625 {
629 }
631 {
633 {
634 tree bitfield_type;
638 }
640 }
642 /* Allow conversion between `__complex__' data types. */
644 {
645 /* The standard conversion sequence to convert FROM to TO is
646 the standard conversion sequence to perform componentwise
647 conversion. */
652 {
655 }
656 else
660 }
670 {
671 /* For backwards brain damage compatibility, allow interconversion of
672 pointers and integers with a pedwarn. */
675 }
677 {
678 /* For backwards brain damage compatibility, allow interconversion of
679 enums and integers with a pedwarn. */
682 }
685 {
686 tree to_pointee;
687 tree from_pointee;
692 ;
696 {
697 from = build_pointer_type
701 }
703 {
708 && (same_type_ignoring_top_level_qualifiers_p
711 {
715 }
718 }
721 /* [conv.ptr]
723 An rvalue of type "pointer to cv D," where D is a
724 class type, can be converted to an rvalue of type
725 "pointer to cv B," where B is a base class (clause
726 _class.derived_) of D. If B is an inaccessible
727 (clause _class.access_) or ambiguous
728 (_class.member.lookup_) base class of D, a program
729 that necessitates this conversion is ill-formed.
730 Therefore, we use DERIVED_FROM_P, and do not check
731 access or uniqueness. */
733 /* If FROM is not yet complete, then we must be parsing
734 the body of a class. We know what's derived from
735 what, but we can't actually perform a
736 derived-to-base conversion. For example, in:
738 struct D : public B {
739 static const int i = sizeof((B*)(D*)0);
740 };
742 the D*-to-B* conversion is a reinterpret_cast, not a
743 static_cast. */
745 {
746 from =
752 }
755 {
758 }
759 else
760 {
763 }
768 /* In a C-style cast, we ignore CV-qualification because we
769 are allowed to perform a static_cast followed by a
770 const_cast. */
775 /* converting from string constant to char *. */
778 {
781 }
782 else
786 }
788 {
808 }
810 {
811 /* [conv.bool]
813 An rvalue of arithmetic, enumeration, pointer, or pointer to
814 member type can be converted to an rvalue of type bool. */
819 {
827 }
830 }
831 /* We don't check for ENUMERAL_TYPE here because there are no standard
832 conversions to enum type. */
835 {
840 /* Give this a better rank if it's a promotion. */
844 }
851 {
855 /* The derived-to-base conversion indicates the initialization
856 of a parameter with base type from an object of a derived
857 type. A temporary object is created to hold the result of
858 the conversion. */
860 }
861 else
865 }
867 /* Returns nonzero if T1 is reference-related to T2. */
869 static bool
871 {
875 /* [dcl.init.ref]
877 Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
878 to "cv2 T2" if T1 is the same type as T2, or T1 is a base class
879 of T2. */
883 }
885 /* Returns nonzero if T1 is reference-compatible with T2. */
887 static bool
889 {
890 /* [dcl.init.ref]
892 "cv1 T1" is reference compatible with "cv2 T2" if T1 is
893 reference-related to T2 and cv1 is the same cv-qualification as,
894 or greater cv-qualification than, cv2. */
897 }
899 /* Determine whether or not the EXPR (of class type S) can be
900 converted to T as in [over.match.ref]. */
904 {
905 tree conversions;
906 tree arglist;
908 tree reference_type;
917 /* [over.match.ref]
919 Assuming that "cv1 T" is the underlying type of the reference
920 being initialized, and "cv S" is the type of the initializer
921 expression, with S a class type, the candidate functions are
922 selected as follows:
924 --The conversion functions of S and its base classes are
925 considered. Those that are not hidden within S and yield type
926 "reference to cv2 T2", where "cv1 T" is reference-compatible
927 (_dcl.init.ref_) with "cv2 T2", are candidate functions.
929 The argument list has one argument, which is the initializer
930 expression. */
934 /* Conceptually, we should take the address of EXPR and put it in
935 the argument list. Unfortunately, however, that can result in
936 error messages, which we should not issue now because we are just
937 trying to find a conversion operator. Therefore, we use NULL,
938 cast to the appropriate type. */
945 {
949 {
955 /* If this is a template function, try to get an exact
956 match. */
958 {
961 NULL_TREE,
962 arglist,
963 reference_type,
966 LOOKUP_NORMAL,
967 DEDUCE_CONV);
970 {
971 /* Now, see if the conversion function really returns
972 an lvalue of the appropriate type. From the
973 point of view of unification, simply returning an
974 rvalue of the right type is good enough. */
979 {
982 }
983 }
984 }
990 LOOKUP_NORMAL);
993 {
995 /* Build a standard conversion sequence indicating the
996 binding from the reference type returned by the
997 function to the desired REFERENCE_TYPE. */
998 identity_conv
1001 NULL_TREE);
1002 cand->second_conv
1003 = (direct_reference_binding
1006 }
1007 }
1009 }
1012 /* If none of the conversion functions worked out, let our caller
1013 know. */
1021 /* Now that we know that this is the function we're going to use fix
1022 the dummy first argument. */
1027 /* Build a user-defined conversion sequence representing the
1028 conversion. */
1034 /* Merge it with the standard conversion sequence from the
1035 conversion function's return type to the desired type. */
1042 }
1044 /* A reference of the indicated TYPE is being bound directly to the
1045 expression represented by the implicit conversion sequence CONV.
1046 Return a conversion sequence for this binding. */
1050 {
1051 tree t;
1058 /* [over.ics.rank]
1060 When a parameter of reference type binds directly
1061 (_dcl.init.ref_) to an argument expression, the implicit
1062 conversion sequence is the identity conversion, unless the
1063 argument expression has a type that is a derived class of the
1064 parameter type, in which case the implicit conversion sequence is
1065 a derived-to-base Conversion.
1067 If the parameter binds directly to the result of applying a
1068 conversion function to the argument expression, the implicit
1069 conversion sequence is a user-defined conversion sequence
1070 (_over.ics.user_), with the second standard conversion sequence
1071 either an identity conversion or, if the conversion function
1072 returns an entity of a type that is a derived class of the
1073 parameter type, a derived-to-base conversion. */
1075 {
1076 /* Represent the derived-to-base conversion. */
1078 /* We will actually be binding to the base-class subobject in
1079 the derived class, so we mark this conversion appropriately.
1080 That way, convert_like knows not to generate a temporary. */
1082 }
1084 }
1086 /* Returns the conversion path from type FROM to reference type TO for
1087 purposes of reference binding. For lvalue binding, either pass a
1088 reference type to FROM or an lvalue expression to EXPR. If the
1089 reference will be bound to a temporary, NEED_TEMPORARY_P is set for
1090 the conversion returned. */
1094 {
1103 {
1108 }
1111 {
1112 /* Anything with reference type is an lvalue. */
1115 }
1119 /* Figure out whether or not the types are reference-related and
1120 reference compatible. We have do do this after stripping
1121 references from FROM. */
1126 {
1127 /* [dcl.init.ref]
1129 If the initializer expression
1131 -- is an lvalue (but not an lvalue for a bit-field), and "cv1 T1"
1132 is reference-compatible with "cv2 T2,"
1134 the reference is bound directly to the initializer expression
1135 lvalue. */
1140 /* For the purposes of overload resolution, we ignore the fact
1141 this expression is a bitfield or packed field. (In particular,
1142 [over.ics.ref] says specifically that a function with a
1143 non-const reference parameter is viable even if the
1144 argument is a bitfield.)
1146 However, when we actually call the function we must create
1147 a temporary to which to bind the reference. If the
1148 reference is volatile, or isn't const, then we cannot make
1149 a temporary, so we just issue an error when the conversion
1150 actually occurs. */
1154 }
1156 {
1157 /* [dcl.init.ref]
1159 If the initializer expression
1161 -- has a class type (i.e., T2 is a class type) can be
1162 implicitly converted to an lvalue of type "cv3 T3," where
1163 "cv1 T1" is reference-compatible with "cv3 T3". (this
1164 conversion is selected by enumerating the applicable
1165 conversion functions (_over.match.ref_) and choosing the
1166 best one through overload resolution. (_over.match_).
1168 the reference is bound to the lvalue result of the conversion
1169 in the second case. */
1173 }
1175 /* From this point on, we conceptually need temporaries, even if we
1176 elide them. Only the cases above are "direct bindings". */
1180 /* [over.ics.rank]
1182 When a parameter of reference type is not bound directly to an
1183 argument expression, the conversion sequence is the one required
1184 to convert the argument expression to the underlying type of the
1185 reference according to _over.best.ics_. Conceptually, this
1186 conversion sequence corresponds to copy-initializing a temporary
1187 of the underlying type with the argument expression. Any
1188 difference in top-level cv-qualification is subsumed by the
1189 initialization itself and does not constitute a conversion. */
1191 /* [dcl.init.ref]
1193 Otherwise, the reference shall be to a non-volatile const type. */
1197 /* [dcl.init.ref]
1199 If the initializer expression is an rvalue, with T2 a class type,
1200 and "cv1 T1" is reference-compatible with "cv2 T2", the reference
1201 is bound in one of the following ways:
1203 -- The reference is bound to the object represented by the rvalue
1204 or to a sub-object within that object.
1206 -- ...
1208 We use the first alternative. The implicit conversion sequence
1209 is supposed to be same as we would obtain by generating a
1210 temporary. Fortunately, if the types are reference compatible,
1211 then this is either an identity conversion or the derived-to-base
1212 conversion, just as for direct binding. */
1214 {
1220 }
1222 /* [dcl.init.ref]
1224 Otherwise, a temporary of type "cv1 T1" is created and
1225 initialized from the initializer expression using the rules for a
1226 non-reference copy initialization. If T1 is reference-related to
1227 T2, cv1 must be the same cv-qualification as, or greater
1228 cv-qualification than, cv2; otherwise, the program is ill-formed. */
1233 flags);
1238 /* This reference binding, unlike those above, requires the
1239 creation of a temporary. */
1243 }
1245 /* Returns the implicit conversion sequence (see [over.ics]) from type
1246 FROM to type TO. The optional expression EXPR may affect the
1247 conversion. FLAGS are the usual overloading flags. Only
1248 LOOKUP_NO_CONVERSION is significant. If C_CAST_P is true, this
1249 conversion is coming from a C-style cast. */
1254 {
1263 else
1273 {
1276 cand = build_user_type_conversion_1
1281 /* We used to try to bind a reference to a temporary here, but that
1282 is now handled by the recursive call to this function at the end
1283 of reference_binding. */
1285 }
1288 }
1290 /* Add a new entry to the list of candidates. Used by the add_*_candidate
1291 functions. */
1299 {
1314 }
1316 /* Create an overload candidate for the function or method FN called with
1317 the argument list ARGLIST and add it to CANDIDATES. FLAGS is passed on
1318 to implicit_conversion.
1320 CTYPE, if non-NULL, is the type we want to pretend this function
1321 comes from for purposes of overload resolution. */
1328 {
1333 tree orig_arglist;
1336 /* At this point we should not see any functions which haven't been
1337 explicitly declared, except for friend functions which will have
1338 been found using argument dependent lookup. */
1341 /* The `this', `in_chrg' and VTT arguments to constructors are not
1342 considered in overload resolution. */
1344 {
1348 }
1349 else
1355 /* 13.3.2 - Viable functions [over.match.viable]
1356 First, to be a viable function, a candidate function shall have enough
1357 parameters to agree in number with the arguments in the list.
1359 We need to check this first; otherwise, checking the ICSes might cause
1360 us to produce an ill-formed template instantiation. */
1364 {
1368 }
1373 /* Make sure there are default args for the rest of the parms. */
1380 /* Second, for F to be a viable function, there shall exist for each
1381 argument an implicit conversion sequence that converts that argument
1382 to the corresponding parameter of F. */
1388 {
1401 {
1404 /* The type of the implicit object parameter ('this') for
1405 overload resolution is not always the same as for the
1406 function itself; conversion functions are considered to
1407 be members of the class being converted, and functions
1408 introduced by a using-declaration are considered to be
1409 members of the class that uses them.
1411 Since build_over_call ignores the ICS for the `this'
1412 parameter, we can just change the parm type. */
1414 {
1415 parmtype
1419 }
1423 }
1424 else
1425 {
1428 }
1435 {
1438 }
1446 }
1448 out:
1451 }
1453 /* Create an overload candidate for the conversion function FN which will
1454 be invoked for expression OBJ, producing a pointer-to-function which
1455 will in turn be called with the argument list ARGLIST, and add it to
1456 CANDIDATES. FLAGS is passed on to implicit_conversion.
1458 Actually, we don't really care about FN; we care about the type it
1459 converts to. There may be multiple conversion functions that will
1460 convert to that type, and we rely on build_user_type_conversion_1 to
1461 choose the best one; so when we create our candidate, we record the type
1462 instead of the function. */
1467 {
1484 /* Don't bother looking up the same type twice. */
1489 {
1496 flags);
1502 else
1503 {
1506 }
1521 }
1531 }
1533 static void
1537 {
1551 {
1558 {
1560 /* We need something for printing the candidate. */
1562 }
1566 }
1568 /* For COND_EXPR we rearranged the arguments; undo that now. */
1570 {
1577 else
1579 }
1585 viable);
1586 }
1588 static bool
1590 {
1592 }
1594 /* Returns nonzero if TYPE is a promoted arithmetic type. */
1596 static bool
1598 {
1599 /* [over.built]
1601 In this section, the term promoted integral type is used to refer
1602 to those integral types which are preserved by integral promotion
1603 (including e.g. int and long but excluding e.g. char).
1604 Similarly, the term promoted arithmetic type refers to promoted
1605 integral types plus floating types. */
1609 }
1611 /* Create any builtin operator overload candidates for the operator in
1612 question given the converted operand types TYPE1 and TYPE2. The other
1613 args are passed through from add_builtin_candidates to
1614 build_builtin_candidate.
1616 TYPE1 and TYPE2 may not be permissible, and we must filter them.
1617 If CODE is requires candidates operands of the same type of the kind
1618 of which TYPE1 and TYPE2 are, we add both candidates
1619 CODE (TYPE1, TYPE1) and CODE (TYPE2, TYPE2). */
1621 static void
1625 {
1627 {
1635 }
1638 {
1640 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
1641 and VQ is either volatile or empty, there exist candidate operator
1642 functions of the form
1643 VQ T& operator++(VQ T&);
1644 T operator++(VQ T&, int);
1645 5 For every pair T, VQ), where T is an enumeration type or an arithmetic
1646 type other than bool, and VQ is either volatile or empty, there exist
1647 candidate operator functions of the form
1648 VQ T& operator--(VQ T&);
1649 T operator--(VQ T&, int);
1650 6 For every pair T, VQ), where T is a cv-qualified or cv-unqualified
1651 complete object type, and VQ is either volatile or empty, there exist
1652 candidate operator functions of the form
1653 T*VQ& operator++(T*VQ&);
1654 T*VQ& operator--(T*VQ&);
1655 T* operator++(T*VQ&, int);
1656 T* operator--(T*VQ&, int); */
1665 {
1668 }
1671 /* 7 For every cv-qualified or cv-unqualified complete object type T, there
1672 exist candidate operator functions of the form
1674 T& operator*(T*);
1676 8 For every function type T, there exist candidate operator functions of
1677 the form
1678 T& operator*(T*); */
1687 /* 9 For every type T, there exist candidate operator functions of the form
1688 T* operator+(T*);
1690 10For every promoted arithmetic type T, there exist candidate operator
1691 functions of the form
1692 T operator+(T);
1693 T operator-(T); */
1703 /* 11For every promoted integral type T, there exist candidate operator
1704 functions of the form
1705 T operator~(T); */
1712 /* 12For every quintuple C1, C2, T, CV1, CV2), where C2 is a class type, C1
1713 is the same type as C2 or is a derived class of C2, T is a complete
1714 object type or a function type, and CV1 and CV2 are cv-qualifier-seqs,
1715 there exist candidate operator functions of the form
1716 CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
1717 where CV12 is the union of CV1 and CV2. */
1722 {
1730 }
1733 /* 13For every pair of promoted arithmetic types L and R, there exist can-
1734 didate operator functions of the form
1735 LR operator*(L, R);
1736 LR operator/(L, R);
1737 LR operator+(L, R);
1738 LR operator-(L, R);
1739 bool operator<(L, R);
1740 bool operator>(L, R);
1741 bool operator<=(L, R);
1742 bool operator>=(L, R);
1743 bool operator==(L, R);
1744 bool operator!=(L, R);
1745 where LR is the result of the usual arithmetic conversions between
1746 types L and R.
1748 14For every pair of types T and I, where T is a cv-qualified or cv-
1749 unqualified complete object type and I is a promoted integral type,
1750 there exist candidate operator functions of the form
1751 T* operator+(T*, I);
1752 T& operator[](T*, I);
1753 T* operator-(T*, I);
1754 T* operator+(I, T*);
1755 T& operator[](I, T*);
1757 15For every T, where T is a pointer to complete object type, there exist
1758 candidate operator functions of the form112)
1759 ptrdiff_t operator-(T, T);
1761 16For every pointer or enumeration type T, there exist candidate operator
1762 functions of the form
1763 bool operator<(T, T);
1764 bool operator>(T, T);
1765 bool operator<=(T, T);
1766 bool operator>=(T, T);
1767 bool operator==(T, T);
1768 bool operator!=(T, T);
1770 17For every pointer to member type T, there exist candidate operator
1771 functions of the form
1772 bool operator==(T, T);
1773 bool operator!=(T, T); */
1779 {
1782 }
1795 {
1798 }
1800 {
1803 }
1804 /* Fall through. */
1821 {
1824 }
1828 {
1831 }
1839 {
1842 }
1844 {
1847 }
1850 /* 18For every pair of promoted integral types L and R, there exist candi-
1851 date operator functions of the form
1852 LR operator%(L, R);
1853 LR operator&(L, R);
1854 LR operator^(L, R);
1855 LR operator|(L, R);
1856 L operator<<(L, R);
1857 L operator>>(L, R);
1858 where LR is the result of the usual arithmetic conversions between
1859 types L and R. */
1871 /* 19For every triple L, VQ, R), where L is an arithmetic or enumeration
1872 type, VQ is either volatile or empty, and R is a promoted arithmetic
1873 type, there exist candidate operator functions of the form
1874 VQ L& operator=(VQ L&, R);
1875 VQ L& operator*=(VQ L&, R);
1876 VQ L& operator/=(VQ L&, R);
1877 VQ L& operator+=(VQ L&, R);
1878 VQ L& operator-=(VQ L&, R);
1880 20For every pair T, VQ), where T is any type and VQ is either volatile
1881 or empty, there exist candidate operator functions of the form
1882 T*VQ& operator=(T*VQ&, T*);
1884 21For every pair T, VQ), where T is a pointer to member type and VQ is
1885 either volatile or empty, there exist candidate operator functions of
1886 the form
1887 VQ T& operator=(VQ T&, T);
1889 22For every triple T, VQ, I), where T is a cv-qualified or cv-
1890 unqualified complete object type, VQ is either volatile or empty, and
1891 I is a promoted integral type, there exist candidate operator func-
1892 tions of the form
1893 T*VQ& operator+=(T*VQ&, I);
1894 T*VQ& operator-=(T*VQ&, I);
1896 23For every triple L, VQ, R), where L is an integral or enumeration
1897 type, VQ is either volatile or empty, and R is a promoted integral
1898 type, there exist candidate operator functions of the form
1900 VQ L& operator%=(VQ L&, R);
1901 VQ L& operator<<=(VQ L&, R);
1902 VQ L& operator>>=(VQ L&, R);
1903 VQ L& operator&=(VQ L&, R);
1904 VQ L& operator^=(VQ L&, R);
1905 VQ L& operator|=(VQ L&, R); */
1909 {
1913 {
1916 }
1942 {
1945 }
1950 }
1955 /* [over.built]
1957 For every pair of promoted arithmetic types L and R, there
1958 exist candidate operator functions of the form
1960 LR operator?(bool, L, R);
1962 where LR is the result of the usual arithmetic conversions
1963 between types L and R.
1965 For every type T, where T is a pointer or pointer-to-member
1966 type, there exist candidate operator functions of the form T
1967 operator?(bool, T, T); */
1971 /* That's OK. */
1974 /* Otherwise, the types should be pointers. */
1979 /* We don't check that the two types are the same; the logic
1980 below will actually create two candidates; one in which both
1981 parameter types are TYPE1, and one in which both parameter
1982 types are TYPE2. */
1987 }
1989 /* If we're dealing with two pointer types or two enumeral types,
1990 we need candidates for both of them. */
1999 {
2000 build_builtin_candidate
2002 build_builtin_candidate
2005 }
2007 build_builtin_candidate
2009 }
2011 tree
2013 {
2019 }
2021 /* There are three conditions of builtin candidates:
2023 1) bool-taking candidates. These are the same regardless of the input.
2024 2) pointer-pair taking candidates. These are generated for each type
2025 one of the input types converts to.
2026 3) arithmetic candidates. According to the standard, we should generate
2027 all of these, but I'm trying not to...
2029 Here we generate a superset of the possible candidates for this particular
2030 case. That is a subset of the full set the standard defines, plus some
2031 other cases which the standard disallows. add_builtin_candidate will
2032 filter out the invalid set. */
2034 static void
2038 {
2042 /* TYPES[i] is the set of possible builtin-operator parameter types
2043 we will consider for the Ith argument. These are represented as
2044 a TREE_LIST; the TREE_VALUE of each node is the potential
2045 parameter type. */
2049 {
2052 else
2054 }
2057 {
2058 /* 4 For every pair T, VQ), where T is an arithmetic or enumeration type,
2059 and VQ is either volatile or empty, there exist candidate operator
2060 functions of the form
2061 VQ T& operator++(VQ T&); */
2071 /* 24There also exist candidate operator functions of the form
2072 bool operator!(bool);
2073 bool operator&&(bool, bool);
2074 bool operator||(bool, bool); */
2077 build_builtin_candidate
2084 build_builtin_candidate
2102 /* Fall through. */
2106 }
2111 {
2113 ;
2115 {
2116 tree convs;
2124 {
2131 }
2137 {
2150 {
2156 }
2160 }
2161 }
2162 else
2163 {
2169 {
2175 }
2177 }
2178 }
2180 /* Run through the possible parameter types of both arguments,
2181 creating candidates with those parameter types. */
2183 {
2186 add_builtin_candidate
2189 else
2190 add_builtin_candidate
2193 }
2194 }
2197 /* If TMPL can be successfully instantiated as indicated by
2198 EXPLICIT_TARGS and ARGLIST, adds the instantiation to CANDIDATES.
2200 TMPL is the template. EXPLICIT_TARGS are any explicit template
2201 arguments. ARGLIST is the arguments provided at the call-site.
2202 The RETURN_TYPE is the desired type for conversion operators. If
2203 OBJ is NULL_TREE, FLAGS and CTYPE are as for add_function_candidate.
2204 If an OBJ is supplied, FLAGS and CTYPE are ignored, and OBJ is as for
2205 add_conv_candidate. */
2212 unification_kind_t strict)
2213 {
2219 tree fn;
2221 /* We don't do deduction on the in-charge parameter, the VTT
2222 parameter or 'this'. */
2232 args_without_in_chrg,
2242 /* In [class.copy]:
2244 A member function template is never instantiated to perform the
2245 copy of a class object to an object of its class type.
2247 It's a little unclear what this means; the standard explicitly
2248 does allow a template to be used to copy a class. For example,
2249 in:
2251 struct A {
2252 A(A&);
2253 template <class T> A(const T&);
2254 };
2255 const A f ();
2256 void g () { A a (f ()); }
2258 the member template will be used to make the copy. The section
2259 quoted above appears in the paragraph that forbids constructors
2260 whose only parameter is (a possibly cv-qualified variant of) the
2261 class type, and a logical interpretation is that the intent was
2262 to forbid the instantiation of member templates which would then
2263 have that form. */
2265 {
2268 ctype))
2270 }
2273 /* Aha, this is a conversion function. */
2276 else
2281 /* This situation can occur if a member template of a template
2282 class is specialized. Then, instantiate_template might return
2283 an instantiation of the specialization, in which case the
2284 DECL_TI_TEMPLATE field will point at the original
2285 specialization. For example:
2287 template <class T> struct S { template <class U> void f(U);
2288 template <> void f(int) {}; };
2289 S<double> sd;
2290 sd.f(3);
2292 Here, TMPL will be template <class U> S<double>::f(U).
2293 And, instantiate template will give us the specialization
2294 template <> S<double>::f(int). But, the DECL_TI_TEMPLATE field
2295 for this will point at template <class T> template <> S<T>::f(int),
2296 so that we can find the definition. For the purposes of
2297 overload resolution, however, we want the original TMPL. */
2299 else
2303 }
2310 unification_kind_t strict)
2311 {
2312 return
2317 }
2324 {
2325 return
2329 }
2331 /* The CANDS are the set of candidates that were considered for
2332 overload resolution. Return the set of viable candidates. If none
2333 of the candidates were viable, set *ANY_VIABLE_P to true. STRICT_P
2334 is true if a candidate should be considered viable only if it is
2335 strictly viable. */
2341 {
2352 {
2355 {
2361 }
2362 else
2364 }
2367 }
2369 static bool
2371 {
2376 }
2378 /* OBJ is being used in an expression like "OBJ.f (...)". In other
2379 words, it is about to become the "this" pointer for a member
2380 function call. Take the address of the object. */
2382 static tree
2384 {
2385 /* In a template, we are only concerned about the type of the
2386 expression, so we can take a shortcut. */
2391 }
2393 /* Returns true iff functions are equivalent. Equivalent functions are
2394 not '==' only if one is a function-local extern function or if
2395 both are extern "C". */
2399 {
2404 }
2406 /* Print information about one overload candidate CANDIDATE. MSGSTR
2407 is the text to print before the candidate itself.
2409 NOTE: Unlike most diagnostic functions in GCC, MSGSTR is expected
2410 to have been run through gettext by the caller. This wart makes
2411 life simpler in print_z_candidates and for the translators. */
2413 static void
2415 {
2417 {
2427 else
2430 }
2435 else
2437 }
2439 static void
2441 {
2446 /* There may be duplicates in the set of candidates. We put off
2447 checking this condition as long as possible, since we have no way
2448 to eliminate duplicates from a set of functions in less than n^2
2449 time. Now we are about to emit an error message, so it is more
2450 permissible to go slowly. */
2452 {
2454 /* Skip builtin candidates and conversion functions. */
2459 {
2463 else
2465 }
2466 }
2474 {
2475 /* Indent successive candidates by the width of the translation
2476 of the above string. */
2483 do
2484 {
2487 }
2489 }
2490 }
2492 /* USER_SEQ is a user-defined conversion sequence, beginning with a
2493 USER_CONV. STD_SEQ is the standard conversion sequence applied to
2494 the result of the conversion function to convert it to the final
2495 desired type. Merge the two sequences into a single sequence,
2496 and return the merged sequence. */
2500 {
2505 /* Find the end of the second conversion sequence. */
2510 /* Replace the identity conversion with the user conversion
2511 sequence. */
2514 /* The entire sequence is a user-conversion sequence. */
2518 }
2520 /* Returns the best overload candidate to perform the requested
2521 conversion. This function is used for three the overloading situations
2522 described in [over.match.copy], [over.match.conv], and [over.match.ref].
2523 If TOTYPE is a REFERENCE_TYPE, we're trying to find an lvalue binding as
2524 per [dcl.init.ref], so we ignore temporary bindings. */
2528 {
2537 /* We represent conversion within a hierarchy using RVALUE_CONV and
2538 BASE_CONV, as specified by [over.best.ics]; these become plain
2539 constructor calls, as specified in [dcl.init]. */
2553 {
2554 tree t;
2560 /* We should never try to call the abstract or base constructor
2561 from here. */
2565 }
2567 {
2577 flags,
2578 DEDUCE_CALL);
2579 else
2583 flags);
2587 }
2593 {
2594 tree fns;
2598 /* If we are called to convert to a reference type, we are trying to
2599 find an lvalue binding, so don't even consider temporaries. If
2600 we don't find an lvalue binding, the caller will try again to
2601 look for a temporary binding. */
2606 {
2609 /* [over.match.funcs] For conversion functions, the function
2610 is considered to be a member of the class of the implicit
2611 object argument for the purpose of defining the type of
2612 the implicit object parameter.
2614 So we pass fromtype as CTYPE to add_*_candidate. */
2618 NULL_TREE,
2621 conversion_path,
2622 flags,
2623 DEDUCE_CONV);
2624 else
2626 args,
2628 conversion_path,
2629 flags);
2632 {
2633 conversion *ics
2645 }
2646 }
2647 }
2655 {
2657 {
2661 }
2668 /* If there are viable candidates, don't set ICS_BAD_FLAG; an
2669 ambiguous conversion is no worse than another user-defined
2670 conversion. */
2673 }
2675 /* Build the user conversion sequence. */
2676 conv = build_conv
2683 /* Combine it with the second conversion sequence. */
2691 }
2693 tree
2695 {
2700 {
2705 }
2707 }
2709 /* Do any initial processing on the arguments to a function call. */
2711 static tree
2713 {
2714 tree t;
2716 {
2722 {
2725 }
2728 }
2730 }
2732 /* Perform overload resolution on FN, which is called with the ARGS.
2734 Return the candidate function selected by overload resolution, or
2735 NULL if the event that overload resolution failed. In the case
2736 that overload resolution fails, *CANDIDATES will be the set of
2737 candidates considered, and ANY_VIABLE_P will be set to true or
2738 false to indicate whether or not any of the candidates were
2739 viable.
2741 The ARGS should already have gone through RESOLVE_ARGS before this
2742 function is called. */
2746 tree args,
2749 {
2757 /* Check FN and ARGS. */
2765 {
2769 }
2771 /* Add the various candidate functions. */
2775 LOOKUP_NORMAL,
2776 candidates);
2784 }
2786 /* Return an expression for a call to FN (a namespace-scope function,
2787 or a static member function) with the ARGS. */
2789 tree
2791 {
2795 tree result;
2801 /* If this function was found without using argument dependent
2802 lookup, then we want to ignore any undeclared friend
2803 functions. */
2805 {
2810 {
2814 }
2815 }
2817 /* Get the high-water mark for the CONVERSION_OBSTACK. */
2823 {
2831 else
2837 }
2838 else
2841 /* Free all the conversions we allocated. */
2845 }
2847 /* Build a call to a global operator new. FNNAME is the name of the
2848 operator (either "operator new" or "operator new[]") and ARGS are
2849 the arguments provided. *SIZE points to the total number of bytes
2850 required by the allocation, and is updated if that is changed here.
2851 *COOKIE_SIZE is non-NULL if a cookie should be used. If this
2852 function determines that no cookie should be used, after all,
2853 *COOKIE_SIZE is set to NULL_TREE. If FN is non-NULL, it will be
2854 set, upon return, to the allocation function called. */
2856 tree
2860 {
2861 tree fns;
2873 /* Based on:
2875 [expr.new]
2877 If this lookup fails to find the name, or if the allocated type
2878 is not a class type, the allocation function's name is looked
2879 up in the global scope.
2881 we disregard block-scope declarations of "operator new". */
2884 /* Figure out what function is being called. */
2887 /* If no suitable function could be found, issue an error message
2888 and give up. */
2890 {
2894 else
2900 }
2902 /* If a cookie is required, add some extra space. Whether
2903 or not a cookie is required cannot be determined until
2904 after we know which function was called. */
2906 {
2909 {
2911 /* In G++ 3.2, the check was implemented incorrectly; it
2912 looked at the placement expression, rather than the
2913 type of the function. */
2916 ptr_type_node))
2918 }
2919 else
2920 {
2921 tree arg_types;
2924 /* Skip the size_t parameter. */
2926 /* Check the remaining parameters (if any). */
2930 ptr_type_node))
2932 }
2933 /* If we need a cookie, adjust the number of bytes allocated. */
2935 {
2936 /* Update the total size. */
2938 /* Update the argument list to reflect the adjusted size. */
2940 }
2941 else
2943 }
2945 /* Tell our caller which function we decided to call. */
2949 /* Build the CALL_EXPR. */
2951 }
2953 static tree
2955 {
2964 {
2965 /* It's no good looking for an overloaded operator() on a
2966 pointer-to-member-function. */
2967 error ("pointer-to-member function %E cannot be called without an object; consider using .* or ->*", obj);
2969 }
2972 {
2976 }
2977 else
2985 /* Get the high-water mark for the CONVERSION_OBSTACK. */
2989 {
2994 {
3002 else
3003 add_function_candidate
3006 }
3007 }
3012 {
3024 {
3027 add_template_conv_candidate
3031 else
3035 }
3036 }
3040 {
3044 }
3045 else
3046 {
3049 {
3053 }
3054 /* Since cand->fn will be a type, not a function, for a conversion
3055 function, we must be careful not to unconditionally look at
3056 DECL_NAME here. */
3060 else
3061 {
3065 }
3066 }
3068 /* Free all the conversions we allocated. */
3072 }
3074 static void
3077 {
3082 else
3086 {
3110 else
3114 }
3115 }
3117 /* Return the implicit conversion sequence that could be used to
3118 convert E1 to E2 in [expr.cond]. */
3122 {
3128 /* [expr.cond]
3130 If E2 is an lvalue: E1 can be converted to match E2 if E1 can be
3131 implicitly converted (clause _conv_) to the type "reference to
3132 T2", subject to the constraint that in the conversion the
3133 reference must bind directly (_dcl.init.ref_) to E1. */
3135 {
3137 t1,
3138 e1,
3140 LOOKUP_NO_TEMP_BIND);
3143 }
3145 /* [expr.cond]
3147 If E1 and E2 have class type, and the underlying class types are
3148 the same or one is a base class of the other: E1 can be converted
3149 to match E2 if the class of T2 is the same type as, or a base
3150 class of, the class of T1, and the cv-qualification of T2 is the
3151 same cv-qualification as, or a greater cv-qualification than, the
3152 cv-qualification of T1. If the conversion is applied, E1 is
3153 changed to an rvalue of type T2 that still refers to the original
3154 source class object (or the appropriate subobject thereof). */
3157 {
3159 {
3164 else
3167 }
3168 else
3170 }
3171 else
3172 /* [expr.cond]
3174 Otherwise: E1 can be converted to match E2 if E1 can be implicitly
3175 converted to the type that expression E2 would have if E2 were
3176 converted to an rvalue (or the type it has, if E2 is an rvalue). */
3178 LOOKUP_NORMAL);
3179 }
3181 /* Implement [expr.cond]. ARG1, ARG2, and ARG3 are the three
3182 arguments to the conditional expression. */
3184 tree
3186 {
3187 tree arg2_type;
3188 tree arg3_type;
3196 /* As a G++ extension, the second argument to the conditional can be
3197 omitted. (So that `a ? : c' is roughly equivalent to `a ? a :
3198 c'.) If the second operand is omitted, make sure it is
3199 calculated only once. */
3201 {
3205 /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */
3208 else
3210 }
3212 /* [expr.cond]
3214 The first expr ession is implicitly converted to bool (clause
3215 _conv_). */
3218 /* If something has already gone wrong, just pass that fact up the
3219 tree. */
3225 /* [expr.cond]
3227 If either the second or the third operand has type (possibly
3228 cv-qualified) void, then the lvalue-to-rvalue (_conv.lval_),
3229 array-to-pointer (_conv.array_), and function-to-pointer
3230 (_conv.func_) standard conversions are performed on the second
3231 and third operands. */
3239 {
3240 /* Do the conversions. We don't these for `void' type arguments
3241 since it can't have any effect and since decay_conversion
3242 does not handle that case gracefully. */
3250 /* [expr.cond]
3252 One of the following shall hold:
3254 --The second or the third operand (but not both) is a
3255 throw-expression (_except.throw_); the result is of the
3256 type of the other and is an rvalue.
3258 --Both the second and the third operands have type void; the
3259 result is of type void and is an rvalue.
3261 We must avoid calling force_rvalue for expressions of type
3262 "void" because it will complain that their value is being
3263 used. */
3266 {
3271 }
3274 {
3279 }
3282 else
3283 {
3286 "is of type %<void%>, "
3287 "but the third operand is neither a throw-expression "
3289 else
3291 "is of type %<void%>, "
3292 "but the second operand is neither a throw-expression "
3295 }
3299 }
3300 /* [expr.cond]
3302 Otherwise, if the second and third operand have different types,
3303 and either has (possibly cv-qualified) class type, an attempt is
3304 made to convert each of those operands to the type of the other. */
3307 {
3311 /* Get the high-water mark for the CONVERSION_OBSTACK. */
3317 /* [expr.cond]
3319 If both can be converted, or one can be converted but the
3320 conversion is ambiguous, the program is ill-formed. If
3321 neither can be converted, the operands are left unchanged and
3322 further checking is performed as described below. If exactly
3323 one conversion is possible, that conversion is applied to the
3324 chosen operand and the converted operand is used in place of
3325 the original operand for the remainder of this section. */
3330 {
3334 }
3336 {
3340 /* Even if CONV2 is a valid conversion, the result of the
3341 conversion may be invalid. For example, if ARG3 has type
3342 "volatile X", and X does not have a copy constructor
3343 accepting a "volatile X&", then even if ARG2 can be
3344 converted to X, the conversion will fail. */
3347 }
3349 {
3355 }
3357 /* Free all the conversions we allocated. */
3363 /* If, after the conversion, both operands have class type,
3364 treat the cv-qualification of both operands as if it were the
3365 union of the cv-qualification of the operands.
3367 The standard is not clear about what to do in this
3368 circumstance. For example, if the first operand has type
3369 "const X" and the second operand has a user-defined
3370 conversion to "volatile X", what is the type of the second
3371 operand after this step? Making it be "const X" (matching
3372 the first operand) seems wrong, as that discards the
3373 qualification without actually performing a copy. Leaving it
3374 as "volatile X" seems wrong as that will result in the
3375 conditional expression failing altogether, even though,
3376 according to this step, the one operand could be converted to
3377 the type of the other. */
3385 }
3387 /* [expr.cond]
3389 If the second and third operands are lvalues and have the same
3390 type, the result is of that type and is an lvalue. */
3394 {
3397 }
3399 /* [expr.cond]
3401 Otherwise, the result is an rvalue. If the second and third
3402 operand do not have the same type, and either has (possibly
3403 cv-qualified) class type, overload resolution is used to
3404 determine the conversions (if any) to be applied to the operands
3405 (_over.match.oper_, _over.built_). */
3409 {
3414 /* Rearrange the arguments so that add_builtin_candidate only has
3415 to know about two args. In build_builtin_candidates, the
3416 arguments are unscrambled. */
3421 COND_EXPR,
3422 NOP_EXPR,
3424 args,
3425 LOOKUP_NORMAL);
3427 /* [expr.cond]
3429 If the overload resolution fails, the program is
3430 ill-formed. */
3433 {
3437 }
3440 {
3444 }
3446 /* [expr.cond]
3448 Otherwise, the conversions thus determined are applied, and
3449 the converted operands are used in place of the original
3450 operands for the remainder of this section. */
3457 }
3459 /* [expr.cond]
3461 Lvalue-to-rvalue (_conv.lval_), array-to-pointer (_conv.array_),
3462 and function-to-pointer (_conv.func_) standard conversions are
3463 performed on the second and third operands.
3465 We need to force the lvalue-to-rvalue conversion here for class types,
3466 so we get TARGET_EXPRs; trying to deal with a COND_EXPR of class rvalues
3467 that isn't wrapped with a TARGET_EXPR plays havoc with exception
3468 regions. */
3481 /* [expr.cond]
3483 After those conversions, one of the following shall hold:
3485 --The second and third operands have the same type; the result is of
3486 that type. */
3489 /* [expr.cond]
3491 --The second and third operands have arithmetic or enumeration
3492 type; the usual arithmetic conversions are performed to bring
3493 them to a common type, and the result is of that type. */
3498 {
3499 /* In this case, there is always a common type. */
3501 arg3_type);
3516 }
3517 /* [expr.cond]
3519 --The second and third operands have pointer type, or one has
3520 pointer type and the other is a null pointer constant; pointer
3521 conversions (_conv.ptr_) and qualification conversions
3522 (_conv.qual_) are performed to bring them to their composite
3523 pointer type (_expr.rel_). The result is of the composite
3524 pointer type.
3526 --The second and third operands have pointer to member type, or
3527 one has pointer to member type and the other is a null pointer
3528 constant; pointer to member conversions (_conv.mem_) and
3529 qualification conversions (_conv.qual_) are performed to bring
3530 them to a common type, whose cv-qualification shall match the
3531 cv-qualification of either the second or the third operand.
3532 The result is of the common type. */
3540 {
3547 }
3550 {
3554 }
3556 valid_operands:
3559 /* We can't use result_type below, as fold might have returned a
3560 throw_expr. */
3563 {
3564 /* Expand both sides into the same slot, hopefully the target of
3565 the ?: expression. We used to check for TARGET_EXPRs here,
3566 but now we sometimes wrap them in NOP_EXPRs so the test would
3567 fail. */
3570 /* If this expression is an rvalue, but might be mistaken for an
3571 lvalue, we must add a NON_LVALUE_EXPR. */
3573 }
3576 }
3578 /* OPERAND is an operand to an expression. Perform necessary steps
3579 required before using it. If OPERAND is NULL_TREE, NULL_TREE is
3580 returned. */
3582 static tree
3584 {
3586 {
3589 /* Make sure the template type is instantiated now. */
3591 }
3594 }
3596 /* Add each of the viable functions in FNS (a FUNCTION_DECL or
3597 OVERLOAD) to the CANDIDATES, returning an updated list of
3598 CANDIDATES. The ARGS are the arguments provided to the call,
3599 without any implicit object parameter. The EXPLICIT_TARGS are
3600 explicit template arguments provided. TEMPLATE_ONLY is true if
3601 only template functions should be considered. CONVERSION_PATH,
3602 ACCESS_PATH, and FLAGS are as for add_function_candidate. */
3604 static void
3610 {
3611 tree ctype;
3612 tree non_static_args;
3615 /* Delay creating the implicit this parameter until it is needed. */
3619 {
3620 tree fn;
3621 tree fn_args;
3624 /* Figure out which set of arguments to use. */
3626 {
3627 /* If this function is a non-static member, prepend the implicit
3628 object parameter. */
3634 }
3635 else
3636 /* Otherwise, just use the list of arguments provided. */
3641 fn,
3642 ctype,
3643 explicit_targs,
3644 fn_args,
3645 NULL_TREE,
3646 access_path,
3647 conversion_path,
3648 flags,
3649 DEDUCE_CALL);
3652 fn,
3653 ctype,
3654 fn_args,
3655 access_path,
3656 conversion_path,
3657 flags);
3659 }
3660 }
3662 tree
3665 {
3683 {
3687 }
3688 else
3694 {
3699 /* Use build_op_new_call and build_op_delete_call instead. */
3707 }
3713 {
3720 }
3735 /* Get the high-water mark for the CONVERSION_OBSTACK. */
3738 /* Add namespace-scope operators to the list of functions to
3739 consider. */
3743 /* Add class-member operators to the candidate set. */
3745 {
3746 tree fns;
3750 {
3753 }
3760 }
3762 /* Rearrange the arguments for ?: so that add_builtin_candidate only has
3763 to know about two args; a builtin candidate will always have a first
3764 parameter of type bool. We'll handle that in
3765 build_builtin_candidate. */
3767 {
3771 }
3772 else
3773 {
3777 }
3782 {
3785 /* For these, the built-in candidates set is empty
3786 [over.match.oper]/3. We don't want non-strict matches
3787 because exact matches are always possible with built-in
3788 operators. The built-in candidate set for COMPONENT_REF
3789 would be empty too, but since there are no such built-in
3790 operators, we accept non-strict matches for them. */
3797 }
3801 {
3803 {
3806 /* Look for an `operator++ (int)'. If they didn't have
3807 one, then we fall back to the old way of doing things. */
3811 fnname,
3815 else
3818 overloaded_p);
3821 /* The caller will deal with these. */
3831 {
3834 }
3837 }
3838 }
3839 else
3840 {
3843 {
3845 {
3848 }
3850 }
3852 {
3857 }
3858 else
3859 {
3860 /* Give any warnings we noticed during overload resolution. */
3862 {
3866 }
3868 /* Check for comparison of different enum types. */
3870 {
3881 {
3884 }
3888 }
3890 /* We need to strip any leading REF_BIND so that bitfields
3891 don't cause errors. This should not remove any important
3892 conversions, because builtins don't apply to class
3893 objects directly. */
3899 {
3904 }
3906 {
3911 }
3912 }
3913 }
3915 user_defined_result_ready:
3917 /* Free all the conversions we allocated. */
3923 builtin:
3925 {
3975 /* The caller will deal with these. */
3983 }
3985 }
3987 /* Build a call to operator delete. This has to be handled very specially,
3988 because the restrictions on what signatures match are different from all
3989 other call instances. For a normal delete, only a delete taking (void *)
3990 or (void *, size_t) is accepted. For a placement delete, only an exact
3991 match with the placement new is accepted.
3993 CODE is either DELETE_EXPR or VEC_DELETE_EXPR.
3994 ADDR is the pointer to be deleted.
3995 SIZE is the size of the memory block to be deleted.
3996 GLOBAL_P is true if the delete-expression should not consider
3997 class-specific delete operators.
3998 PLACEMENT is the corresponding placement new call, or NULL_TREE.
3999 If PLACEMENT is non-NULL, then ALLOC_FN is the allocation function
4000 called to perform the placement new. */
4002 tree
4005 tree alloc_fn)
4006 {
4021 /* In [class.free]
4023 If the result of the lookup is ambiguous or inaccessible, or if
4024 the lookup selects a placement deallocation function, the
4025 program is ill-formed.
4027 Therefore, we ask lookup_fnfields to complain about ambiguity. */
4028 {
4032 }
4033 else
4040 {
4041 /* Get the parameter types for the allocation function that is
4042 being called. */
4045 /* Also the second argument. */
4047 }
4048 else
4049 {
4050 /* First try it without the size argument. */
4053 }
4055 /* Strip const and volatile from addr. */
4058 /* We make two tries at finding a matching `operator delete'. On
4059 the first pass, we look for a one-operator (or placement)
4060 operator delete. If we're not doing placement delete, then on
4061 the second pass we look for a two-argument delete. */
4063 {
4064 /* Go through the `operator delete' functions looking for one
4065 with a matching type. */
4067 fn;
4069 {
4070 tree t;
4072 /* The first argument must be "void *". */
4077 /* On the first pass, check the rest of the arguments. */
4079 {
4082 {
4087 }
4090 }
4091 /* On the second pass, the second argument must be
4092 "size_t". */
4097 }
4099 /* If we found a match, we're done. */
4102 }
4104 /* If we have a matching function, call it. */
4106 {
4107 /* Make sure we have the actual function, and not an
4108 OVERLOAD. */
4111 /* If the FN is a member function, make sure that it is
4112 accessible. */
4118 else
4123 {
4124 /* The placement args might not be suitable for overload
4125 resolution at this point, so build the call directly. */
4128 }
4129 else
4131 }
4133 /* If we are doing placement delete we do nothing if we don't find a
4134 matching op delete. */
4141 }
4143 /* If the current scope isn't allowed to access DECL along
4144 BASETYPE_PATH, give an error. The most derived class in
4145 BASETYPE_PATH is the one used to qualify DECL. DIAG_DECL is
4146 the declaration to use in the error diagnostic. */
4148 bool
4150 {
4154 {
4159 else
4163 }
4166 }
4168 /* Check that a callable constructor to initialize a temporary of
4169 TYPE from an EXPR exists. */
4171 static void
4173 {
4175 complete_ctor_identifier,
4177 type,
4178 LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING
4179 | LOOKUP_NO_CONVERSION
4181 }
4183 /* Initialize a temporary of type TYPE with EXPR. The FLAGS are a
4184 bitwise or of LOOKUP_* values. If any errors are warnings are
4185 generated, set *DIAGNOSTIC_FN to "error" or "warning",
4186 respectively. If no diagnostics are generated, set *DIAGNOSTIC_FN
4187 to NULL. */
4189 static tree
4192 {
4197 complete_ctor_identifier,
4204 else
4207 }
4210 /* Perform the conversions in CONVS on the expression EXPR. FN and
4211 ARGNUM are used for diagnostics. ARGNUM is zero based, -1
4212 indicates the `this' argument of a method. INNER is nonzero when
4213 being called to continue a conversion chain. It is negative when a
4214 reference binding will be applied, positive otherwise. If
4215 ISSUE_CONVERSION_WARNINGS is true, warnings about suspicious
4216 conversions will be emitted if appropriate. If C_CAST_P is true,
4217 this conversion is coming from a C-style cast; in that case,
4218 conversions to inaccessible bases are permitted. */
4220 static tree
4224 {
4226 diagnostic_fn_t diagnostic_fn;
4232 {
4235 {
4237 {
4242 }
4249 }
4254 }
4257 {
4260 /* Issue warnings about peculiar, but valid, uses of NULL. */
4262 {
4266 else
4268 }
4270 /* Warn about assigning a floating-point type to an integer type. */
4273 {
4277 else
4279 }
4280 }
4283 {
4285 {
4288 tree args;
4291 {
4296 /* We should never try to call the abstract or base constructor
4297 from here. */
4301 }
4302 else
4306 /* If this is a constructor or a function returning an aggr type,
4307 we need to build up a TARGET_EXPR. */
4311 /* The result of the call is then used to direct-initialize the object
4312 that is the destination of the copy-initialization. [dcl.init]
4314 Note that this step is not reflected in the conversion sequence;
4315 it affects the semantics when we actually perform the
4316 conversion, but is not considered during overload resolution.
4318 If the target is a class, that means call a ctor. */
4321 {
4322 expr = (build_temp
4324 /* Core issue 84, now a DR, says that we don't
4325 allow UDCs for these args (which deliberately
4326 breaks copy-init of an auto_ptr<Base> from an
4327 auto_ptr<Derived>). */
4332 {
4334 diagnostic_fn
4337 else
4338 diagnostic_fn
4340 }
4342 }
4344 }
4348 /* Convert a constant to its underlying value, unless we are
4349 about to bind it to a reference, in which case we need to
4350 leave it as an lvalue. */
4357 /* Call build_user_type_conversion again for the error. */
4358 return build_user_type_conversion
4363 };
4368 c_cast_p);
4373 {
4378 /* Else fall through. */
4381 {
4382 /* We are going to bind a reference directly to a base-class
4383 subobject of EXPR. */
4386 /* Build an expression for `*((base*) &expr)'. */
4392 }
4394 /* Copy-initialization where the cv-unqualified version of the source
4395 type is the same class as, or a derived class of, the class of the
4396 destination [is treated as direct-initialization]. [dcl.init] */
4404 {
4407 /* If necessary, create a temporary. */
4409 {
4414 {
4415 /* If the reference is volatile or non-const, we
4416 cannot create a temporary. */
4423 else
4426 }
4427 /* If the source is a packed field, and we must use a copy
4428 constructor, then building the target expr will require
4429 binding the field to the reference parameter to the
4430 copy constructor, and we'll end up with an infinite
4431 loop. If we can use a bitwise copy, then we'll be
4432 OK. */
4436 {
4440 }
4442 }
4444 /* Take the address of the thing to which we will bind the
4445 reference. */
4450 /* Convert it to a pointer to the type referred to by the
4451 reference. This will adjust the pointer if a derived to
4452 base conversion is being performed. */
4454 expr);
4455 /* Convert the pointer to the desired reference type. */
4457 }
4463 /* Warn about deprecated conversion if appropriate. */
4475 c_cast_p);
4479 }
4483 else
4487 }
4489 /* Build a call to __builtin_trap. */
4491 static tree
4493 {
4499 }
4501 /* ARG is being passed to a varargs function. Perform any conversions
4502 required. Return the converted value. */
4504 tree
4506 {
4507 /* [expr.call]
4509 The lvalue-to-rvalue, array-to-pointer, and function-to-pointer
4510 standard conversions are performed. */
4512 /* [expr.call]
4514 If the argument has integral or enumeration type that is subject
4515 to the integral promotions (_conv.prom_), or a floating point
4516 type that is subject to the floating point promotion
4517 (_conv.fpprom_), the value of the argument is converted to the
4518 promoted type before the call. */
4530 {
4531 /* Undefined behavior [expr.call] 5.2.2/7. We used to just warn
4532 here and do a bitwise copy, but now cp_expr_size will abort if we
4533 try to do that.
4534 If the call appears in the context of a sizeof expression,
4535 there is no need to emit a warning, since the expression won't be
4536 evaluated. We keep the builtin_trap just as a safety check. */
4542 integer_zero_node);
4543 }
4546 }
4548 /* va_arg (EXPR, TYPE) is a builtin. Make sure it is not abused. */
4550 tree
4552 {
4562 {
4563 /* Remove reference types so we don't ICE later on. */
4565 /* Undefined behavior [expr.call] 5.2.2/7. */
4573 }
4576 }
4578 /* TYPE has been given to va_arg. Apply the default conversions which
4579 would have happened when passed via ellipsis. Return the promoted
4580 type, or the passed type if there is no change. */
4582 tree
4584 {
4585 tree promote;
4587 /* Perform the array-to-pointer and function-to-pointer
4588 conversions. */
4596 }
4598 /* ARG is a default argument expression being passed to a parameter of
4599 the indicated TYPE, which is a parameter to FN. Do any required
4600 conversions. Return the converted value. */
4602 tree
4604 {
4605 /* If the ARG is an unparsed default argument expression, the
4606 conversion cannot be performed. */
4608 {
4613 }
4621 {
4625 }
4626 else
4627 {
4628 /* This could get clobbered by the following call. */
4635 }
4638 }
4640 /* Returns the type which will really be used for passing an argument of
4641 type TYPE. */
4643 tree
4645 {
4646 /* Pass classes with copy ctors by invisible reference. */
4648 {
4650 /* There are no other pointers to this temporary. */
4652 }
4661 }
4663 /* Actually perform the appropriate conversion. */
4665 tree
4667 {
4669 ;
4670 /* Pass classes with copy ctors by invisible reference. */
4680 {
4689 }
4691 }
4693 /* Returns true iff FN is a function with magic varargs, i.e. ones for
4694 which no conversions at all should be done. This is true for some
4695 builtins which don't act like normal functions. */
4697 static bool
4699 {
4702 {
4711 }
4714 }
4716 /* Subroutine of the various build_*_call functions. Overload resolution
4717 has chosen a winning candidate CAND; build up a CALL_EXPR accordingly.
4718 ARGS is a TREE_LIST of the unconverted arguments to the call. FLAGS is a
4719 bitmask of various LOOKUP_* flags which apply to the call itself. */
4721 static tree
4723 {
4734 /* In a template, there is no need to perform all of the work that
4735 is normally done. We are only interested in the type of the call
4736 expression, i.e., the return type of the function. Any semantic
4737 errors will be deferred until the template is instantiated. */
4739 {
4740 tree expr;
4741 tree return_type;
4749 }
4751 /* Give any warnings we noticed during overload resolution. */
4753 {
4757 }
4760 {
4761 /* If FN is a template function, two cases must be considered.
4762 For example:
4764 struct A {
4765 protected:
4766 template <class T> void f();
4767 };
4768 template <class T> struct B {
4769 protected:
4770 void g();
4771 };
4772 struct C : A, B<int> {
4773 using A::f; // #1
4774 using B<int>::g; // #2
4775 };
4777 In case #1 where `A::f' is a member template, DECL_ACCESS is
4778 recorded in the primary template but not in its specialization.
4779 We check access of FN using its primary template.
4781 In case #2, where `B<int>::g' has a DECL_TEMPLATE_INFO simply
4782 because it is a member of class template B, DECL_ACCESS is
4783 recorded in the specialization `B<int>::g'. We cannot use its
4784 primary template because `B<T>::g' and `B<int>::g' may have
4785 different access. */
4790 else
4792 }
4798 /* The implicit parameters to a constructor are not considered by overload
4799 resolution, and must be of the proper type. */
4801 {
4805 /* We should never try to call the abstract constructor. */
4809 {
4810 converted_args = tree_cons
4814 }
4815 }
4816 /* Bypass access control for 'this' parameter. */
4818 {
4821 tree converted_arg;
4822 tree base_binfo;
4828 /* [class.mfct.nonstatic]: If a nonstatic member function of a class
4829 X is called for an object that is not of type X, or of a type
4830 derived from X, the behavior is undefined.
4832 So we can assume that anything passed as 'this' is non-null, and
4833 optimize accordingly. */
4835 /* Convert to the base in which the function was declared. */
4841 /* Check that the base class is accessible. */
4847 /* If fn was found by a using declaration, the conversion path
4848 will be to the derived class, not the base declaring fn. We
4849 must convert from derived to base. */
4860 }
4864 {
4869 /* Don't make a copy here if build_call is going to. */
4874 val = convert_like_with_context
4879 }
4881 /* Default arguments */
4883 converted_args
4888 converted_args);
4890 /* Ellipsis */
4892 {
4896 else
4899 }
4906 /* Avoid actually calling copy constructors and copy assignment operators,
4907 if possible. */
4912 {
4913 tree targ;
4917 /* Pull out the real argument, disregarding const-correctness. */
4924 {
4929 }
4930 else
4935 else
4938 /* [class.copy]: the copy constructor is implicitly defined even if
4939 the implementation elided its use. */
4943 /* If we're creating a temp and we already have one, don't create a
4944 new one. If we're not creating a temp but we get one, use
4945 INIT_EXPR to collapse the temp into our target. Otherwise, if the
4946 ctor is trivial, do a bitwise copy with a simple TARGET_EXPR for a
4947 temp or an INIT_EXPR otherwise. */
4949 {
4954 }
4957 {
4958 tree to = stabilize_reference
4963 }
4964 }
4968 {
4969 tree to = stabilize_reference
4976 {
4979 }
4980 else
4981 {
4982 /* We must only copy the non-tail padding parts.
4983 Use __builtin_memcpy for the bitwise copy. */
4996 }
4999 }
5004 {
5017 else
5020 }
5023 else
5027 }
5029 /* Build and return a call to FN, using ARGS. This function performs
5030 no overload resolution, conversion, or other high-level
5031 operations. */
5033 tree
5035 {
5036 tree fndecl;
5040 /* If this call might throw an exception, note that fact. */
5047 /* Some built-in function calls will be evaluated at compile-time in
5048 fold (). */
5061 }
5065 /* Make an expression which yields the address of the Java interface
5066 method FN. This is achieved by generating a call to libjava's
5067 _Jv_LookupInterfaceMethodIdx(). */
5069 static tree
5071 {
5077 {
5082 endlink)));
5083 java_iface_lookup_fn
5087 }
5089 /* Look up the pointer to the runtime java.lang.Class object for `instance'.
5090 This is the first entry in the vtable. */
5092 integer_zero_node);
5094 /* Get the java.lang.Class pointer for the interface being called. */
5099 {
5101 iface);
5103 }
5107 /* Determine the itable index of FN. */
5110 {
5115 i++;
5116 }
5124 java_iface_lookup_fn);
5126 }
5128 /* Returns the value to use for the in-charge parameter when making a
5129 call to a function with the indicated NAME.
5131 FIXME:Can't we find a neater way to do this mapping? */
5133 tree
5135 {
5146 /* This function should only be called with one of the names listed
5147 above. */
5150 }
5152 /* Build a call to a constructor, destructor, or an assignment
5153 operator for INSTANCE, an expression with class type. NAME
5154 indicates the special member function to call; ARGS are the
5155 arguments. BINFO indicates the base of INSTANCE that is to be
5156 passed as the `this' parameter to the member function called.
5158 FLAGS are the LOOKUP_* flags to use when processing the call.
5160 If NAME indicates a complete object constructor, INSTANCE may be
5161 NULL_TREE. In this case, the caller will call build_cplus_new to
5162 store the newly constructed object into a VAR_DECL. */
5164 tree
5167 {
5168 tree fns;
5169 /* The type of the subobject to be constructed or destroyed. */
5170 tree class_type;
5179 {
5180 /* Resolve the name. */
5185 }
5191 /* Handle the special case where INSTANCE is NULL_TREE. */
5193 {
5196 }
5197 else
5198 {
5204 /* Convert to the base class, if necessary. */
5207 {
5209 /* For constructors and destructors, either the base is
5210 non-virtual, or it is virtual but we are doing the
5211 conversion from a constructor or destructor for the
5212 complete object. In either case, we can convert
5213 statically. */
5215 else
5216 /* However, for assignment operators, we must convert
5217 dynamically if the base is virtual. */
5220 }
5221 }
5227 /* When making a call to a constructor or destructor for a subobject
5228 that uses virtual base classes, pass down a pointer to a VTT for
5229 the subobject. */
5233 {
5234 tree vtt;
5235 tree sub_vtt;
5237 /* If the current function is a complete object constructor
5238 or destructor, then we fetch the VTT directly.
5239 Otherwise, we look it up using the VTT we were given. */
5245 current_vtt_parm,
5246 vtt);
5252 }
5257 }
5259 /* Return the NAME, as a C string. The NAME indicates a function that
5260 is a member of TYPE. *FREE_P is set to true if the caller must
5261 free the memory returned.
5263 Rather than go through all of this, we should simply set the names
5264 of constructors and destructors appropriately, and dispense with
5265 ctor_identifier, dtor_identifier, etc. */
5269 {
5272 /* Assume that we will not allocate memory. */
5274 /* Constructors and destructors are special. */
5276 {
5277 pretty_name
5279 /* For a destructor, add the '~'. */
5283 {
5285 /* Remember that we need to free the memory allocated. */
5287 }
5288 }
5290 {
5293 TFF_PLAIN_IDENTIFIER),
5294 NULL);
5295 /* Remember that we need to free the memory allocated. */
5297 }
5298 else
5302 }
5304 /* Build a call to "INSTANCE.FN (ARGS)". If FN_P is non-NULL, it will
5305 be set, upon return, to the function called. */
5307 tree
5311 {
5315 tree access_binfo;
5316 tree optype;
5318 tree name;
5319 tree user_args;
5320 tree call;
5321 tree fn;
5322 tree class_type;
5325 tree orig_instance;
5326 tree orig_fns;
5327 tree orig_args;
5332 /* We don't know what function we're going to call, yet. */
5342 {
5345 }
5351 /* Dismantle the baselink to collect all the information we need. */
5358 {
5362 }
5373 {
5376 }
5378 /* The USER_ARGS are the arguments we will display to users if an
5379 error occurs. The USER_ARGS should not include any
5380 compiler-generated arguments. The "this" pointer hasn't been
5381 added yet. However, we must remove the VTT pointer if this is a
5382 call to a base-class constructor or destructor. */
5385 {
5386 /* Callers should explicitly indicate whether they want to construct
5387 the complete object or just the part without virtual bases. */
5389 /* Similarly for destructors. */
5391 /* Remove the VTT pointer, if present. */
5395 }
5397 /* Process the argument list. */
5404 /* It's OK to call destructors on cv-qualified objects. Therefore,
5405 convert the INSTANCE_PTR to the unqualified type, if necessary. */
5407 {
5412 }
5417 /* Get the high-water mark for the CONVERSION_OBSTACK. */
5421 {
5423 tree this_arglist;
5425 /* We can end up here for copy-init of same or base class. */
5432 else
5436 /* A member template. */
5438 class_type,
5439 explicit_targs,
5441 access_binfo,
5442 conversion_path,
5443 flags,
5444 DEDUCE_CALL);
5447 class_type,
5448 this_arglist,
5449 access_binfo,
5450 conversion_path,
5451 flags);
5452 }
5456 {
5459 else
5460 {
5470 }
5473 }
5474 else
5475 {
5478 {
5484 user_args);
5489 }
5490 else
5491 {
5499 /* This is not an error, it is runtime undefined
5500 behavior. */
5502 "abstract virtual %q#D called from constructor"
5504 fn);
5508 {
5510 fn);
5512 }
5513 else
5514 {
5518 /* Now we know what function is being called. */
5521 /* Build the actual CALL_EXPR. */
5523 /* In an expression of the form `a->f()' where `f' turns
5524 out to be a static member function, `a' is
5525 none-the-less evaluated. */
5534 /* An explicit call of the form "x->~X()" has type
5535 "void". However, on platforms where destructors
5536 return "this" (i.e., those where
5537 targetm.cxx.cdtor_returns_this is true), such calls
5538 will appear to have a return value of pointer type
5539 to the low-level call machinery. We do not want to
5540 change the low-level machinery, since we want to be
5541 able to optimize "delete f()" on such platforms as
5542 "operator delete(~X(f()))" (rather than generating
5543 "t = f(), ~X(t), operator delete (t)"). */
5545 }
5546 }
5547 }
5550 call = (build_min_non_dep_call_list
5553 orig_args));
5555 /* Free all the conversions we allocated. */
5559 }
5561 /* Returns true iff standard conversion sequence ICS1 is a proper
5562 subsequence of ICS2. */
5564 static bool
5566 {
5567 /* We can assume that a conversion of the same code
5568 between the same types indicates a subsequence since we only get
5569 here if the types we are converting from are the same. */
5576 {
5584 /* At this point, ICS1 cannot be a proper subsequence of
5585 ICS2. We can get a USER_CONV when we are comparing the
5586 second standard conversion sequence of two user conversion
5587 sequences. */
5597 }
5598 }
5600 /* Returns nonzero iff DERIVED is derived from BASE. The inputs may
5601 be any _TYPE nodes. */
5603 bool
5605 {
5610 /* We only allow proper derivation here. The DERIVED_FROM_P macro
5611 considers every class derived from itself. */
5614 }
5616 /* We build the ICS for an implicit object parameter as a pointer
5617 conversion sequence. However, such a sequence should be compared
5618 as if it were a reference conversion sequence. If ICS is the
5619 implicit conversion sequence for an implicit object parameter,
5620 modify it accordingly. */
5622 static void
5624 {
5626 {
5627 /* [over.match.funcs]
5629 For non-static member functions, the type of the
5630 implicit object parameter is "reference to cv X"
5631 where X is the class of which the function is a
5632 member and cv is the cv-qualification on the member
5633 function declaration. */
5635 tree reference_type;
5637 /* The `this' parameter is a pointer to a class type. Make the
5638 implicit conversion talk about a reference to that same class
5639 type. */
5650 }
5651 }
5653 /* If *ICS is a REF_BIND set *ICS to the remainder of the conversion,
5654 and return the type to which the reference refers. Otherwise,
5655 leave *ICS unchanged and return NULL_TREE. */
5657 static tree
5659 {
5661 {
5668 }
5671 }
5673 /* Compare two implicit conversion sequences according to the rules set out in
5674 [over.ics.rank]. Return values:
5676 1: ics1 is better than ics2
5677 -1: ics2 is better than ics1
5678 0: ics1 and ics2 are indistinguishable */
5680 static int
5682 {
5683 tree from_type1;
5684 tree from_type2;
5685 tree to_type1;
5686 tree to_type2;
5693 /* REF_BINDING is nonzero if the result of the conversion sequence
5694 is a reference type. In that case TARGET_TYPE is the
5695 type referred to by the reference. */
5696 tree target_type1;
5697 tree target_type2;
5699 /* Handle implicit object parameters. */
5703 /* Handle reference parameters. */
5707 /* [over.ics.rank]
5709 When comparing the basic forms of implicit conversion sequences (as
5710 defined in _over.best.ics_)
5712 --a standard conversion sequence (_over.ics.scs_) is a better
5713 conversion sequence than a user-defined conversion sequence
5714 or an ellipsis conversion sequence, and
5716 --a user-defined conversion sequence (_over.ics.user_) is a
5717 better conversion sequence than an ellipsis conversion sequence
5718 (_over.ics.ellipsis_). */
5728 {
5729 /* XXX Isn't this an extension? */
5730 /* Both ICS are bad. We try to make a decision based on what
5731 would have happened if they'd been good. */
5739 /* We couldn't make up our minds; try to figure it out below. */
5740 }
5743 /* Both conversions are ellipsis conversions. */
5746 /* User-defined conversion sequence U1 is a better conversion sequence
5747 than another user-defined conversion sequence U2 if they contain the
5748 same user-defined conversion operator or constructor and if the sec-
5749 ond standard conversion sequence of U1 is better than the second
5750 standard conversion sequence of U2. */
5753 {
5767 /* We can just fall through here, after setting up
5768 FROM_TYPE1 and FROM_TYPE2. */
5771 }
5772 else
5773 {
5777 /* We're dealing with two standard conversion sequences.
5779 [over.ics.rank]
5781 Standard conversion sequence S1 is a better conversion
5782 sequence than standard conversion sequence S2 if
5784 --S1 is a proper subsequence of S2 (comparing the conversion
5785 sequences in the canonical form defined by _over.ics.scs_,
5786 excluding any Lvalue Transformation; the identity
5787 conversion sequence is considered to be a subsequence of
5788 any non-identity conversion sequence */
5799 }
5802 {
5807 }
5808 /* Otherwise, one sequence cannot be a subsequence of the other; they
5809 don't start with the same type. This can happen when comparing the
5810 second standard conversion sequence in two user-defined conversion
5811 sequences. */
5813 /* [over.ics.rank]
5815 Or, if not that,
5817 --the rank of S1 is better than the rank of S2 (by the rules
5818 defined below):
5820 Standard conversion sequences are ordered by their ranks: an Exact
5821 Match is a better conversion than a Promotion, which is a better
5822 conversion than a Conversion.
5824 Two conversion sequences with the same rank are indistinguishable
5825 unless one of the following rules applies:
5827 --A conversion that is not a conversion of a pointer, or pointer
5828 to member, to bool is better than another conversion that is such
5829 a conversion.
5831 The ICS_STD_RANK automatically handles the pointer-to-bool rule,
5832 so that we do not have to check it explicitly. */
5845 {
5850 }
5851 /* The rules for pointers to members A::* are just like the rules
5852 for pointers A*, except opposite: if B is derived from A then
5853 A::* converts to B::*, not vice versa. For that reason, we
5854 switch the from_ and to_ variables here. */
5861 {
5866 }
5871 {
5872 /* This was one of the pointer or pointer-like conversions.
5874 [over.ics.rank]
5876 --If class B is derived directly or indirectly from class A,
5877 conversion of B* to A* is better than conversion of B* to
5878 void*, and conversion of A* to void* is better than
5879 conversion of B* to void*. */
5882 {
5884 deref_from_type2))
5887 deref_from_type1))
5889 }
5892 {
5894 {
5896 {
5898 deref_to_type1))
5900 }
5901 /* We know that DEREF_TO_TYPE1 is `void' here. */
5903 deref_to_type2))
5905 }
5906 }
5909 {
5910 /* [over.ics.rank]
5912 --If class B is derived directly or indirectly from class A
5913 and class C is derived directly or indirectly from B,
5915 --conversion of C* to B* is better than conversion of C* to
5916 A*,
5918 --conversion of B* to A* is better than conversion of C* to
5919 A* */
5921 {
5923 deref_to_type2))
5926 deref_to_type1))
5928 }
5930 {
5932 deref_from_type1))
5935 deref_from_type2))
5937 }
5938 }
5939 }
5942 {
5945 /* [over.ics.rank]
5947 --binding of an expression of type C to a reference of type
5948 B& is better than binding an expression of type C to a
5949 reference of type A&
5951 --conversion of C to B is better than conversion of C to A, */
5954 {
5959 }
5960 }
5963 {
5966 /* [over.ics.rank]
5968 --binding of an expression of type B to a reference of type
5969 A& is better than binding an expression of type C to a
5970 reference of type A&,
5972 --conversion of B to A is better than conversion of C to A */
5975 {
5980 }
5981 }
5983 /* [over.ics.rank]
5985 --S1 and S2 differ only in their qualification conversion and yield
5986 similar types T1 and T2 (_conv.qual_), respectively, and the cv-
5987 qualification signature of type T1 is a proper subset of the cv-
5988 qualification signature of type T2 */
5994 /* [over.ics.rank]
5996 --S1 and S2 are reference bindings (_dcl.init.ref_), and the
5997 types to which the references refer are the same type except for
5998 top-level cv-qualifiers, and the type to which the reference
5999 initialized by S2 refers is more cv-qualified than the type to
6000 which the reference initialized by S1 refers */
6006 /* Neither conversion sequence is better than the other. */
6008 }
6010 /* The source type for this standard conversion sequence. */
6012 static tree
6014 {
6016 {
6021 }
6023 }
6025 /* Note a warning about preferring WINNER to LOSER. We do this by storing
6026 a pointer to LOSER and re-running joust to produce the warning if WINNER
6027 is actually used. */
6029 static void
6031 {
6037 }
6039 /* Compare two candidates for overloading as described in
6040 [over.match.best]. Return values:
6042 1: cand1 is better than cand2
6043 -1: cand2 is better than cand1
6044 0: cand1 and cand2 are indistinguishable */
6046 static int
6048 {
6054 /* Candidates that involve bad conversions are always worse than those
6055 that don't. */
6061 /* If we have two pseudo-candidates for conversions to the same type,
6062 or two candidates for the same function, arbitrarily pick one. */
6067 /* a viable function F1
6068 is defined to be a better function than another viable function F2 if
6069 for all arguments i, ICSi(F1) is not a worse conversion sequence than
6070 ICSi(F2), and then */
6072 /* for some argument j, ICSj(F1) is a better conversion sequence than
6073 ICSj(F2) */
6075 /* For comparing static and non-static member functions, we ignore
6076 the implicit object parameter of the non-static function. The
6077 standard says to pretend that the static function has an object
6078 parm, but that won't work with operator overloading. */
6081 {
6089 else
6090 {
6093 }
6094 }
6097 {
6103 {
6116 {
6123 else
6128 {
6132 }
6133 else
6135 }
6138 {
6141 }
6143 }
6144 }
6146 /* warn about confusing overload resolution for user-defined conversions,
6147 either between a constructor and a conversion op, or between two
6148 conversion ops. */
6152 {
6158 else
6161 /* We don't want to complain about `X::operator T1 ()'
6162 beating `X::operator T2 () const', when T2 is a no less
6163 cv-qualified version of T1. */
6166 {
6171 {
6174 }
6177 }
6178 else
6184 {
6192 }
6193 else
6195 }
6200 /* or, if not that,
6201 F1 is a non-template function and F2 is a template function
6202 specialization. */
6209 /* or, if not that,
6210 F1 and F2 are template functions and the function template for F1 is
6211 more specialized than the template for F2 according to the partial
6212 ordering rules. */
6215 {
6216 winner = more_specialized_fn
6219 /* [temp.func.order]: The presence of unused ellipsis and default
6220 arguments has no effect on the partial ordering of function
6221 templates. add_function_candidate() will not have
6222 counted the "this" argument for constructors. */
6226 }
6228 /* or, if not that,
6229 the context is an initialization by user-defined conversion (see
6230 _dcl.init_ and _over.match.user_) and the standard conversion
6231 sequence from the return type of F1 to the destination type (i.e.,
6232 the type of the entity being initialized) is a better conversion
6233 sequence than the standard conversion sequence from the return type
6234 of F2 to the destination type. */
6237 {
6241 }
6243 /* Check whether we can discard a builtin candidate, either because we
6244 have two identical ones or matching builtin and non-builtin candidates.
6246 (Pedantically in the latter case the builtin which matched the user
6247 function should not be added to the overload set, but we spot it here.
6249 [over.match.oper]
6250 ... the builtin candidates include ...
6251 - do not have the same parameter type list as any non-template
6252 non-member candidate. */
6256 {
6262 {
6264 /* Two built-in candidates; arbitrarily pick one. */
6267 /* cand1 is built-in; prefer cand2. */
6269 else
6270 /* cand2 is built-in; prefer cand1. */
6272 }
6273 }
6275 /* If the two functions are the same (this can happen with declarations
6276 in multiple scopes and arg-dependent lookup), arbitrarily choose one. */
6281 tweak:
6283 /* Extension: If the worst conversion for one candidate is worse than the
6284 worst conversion for the other, take the first. */
6286 {
6291 {
6296 }
6302 {
6304 {
6306 ISO C++ says that these are ambiguous, even \
6307 though the worst conversion for the first is better than \
6311 }
6312 else
6315 }
6316 }
6320 }
6322 /* Given a list of candidates for overloading, find the best one, if any.
6323 This algorithm has a worst case of O(2n) (winner is last), and a best
6324 case of O(n/2) (totally ambiguous); much better than a sorting
6325 algorithm. */
6329 {
6334 /* Walk through the list once, comparing each current champ to the next
6335 candidate, knocking out a candidate or two with each comparison. */
6338 {
6342 else
6343 {
6345 {
6350 }
6351 else
6352 {
6355 }
6358 }
6359 }
6361 /* Make sure the champ is better than all the candidates it hasn't yet
6362 been compared to. */
6365 challenger != champ
6368 {
6372 }
6375 }
6377 /* Returns nonzero if things of type FROM can be converted to TO. */
6379 bool
6381 {
6383 }
6385 /* Returns nonzero if ARG (of type FROM) can be converted to TO. */
6387 bool
6389 {
6394 /* Get the high-water mark for the CONVERSION_OBSTACK. */
6398 flags);
6401 /* Free all the conversions we allocated. */
6405 }
6407 /* Like can_convert_arg, but allows dubious conversions as well. */
6409 bool
6411 {
6415 /* Get the high-water mark for the CONVERSION_OBSTACK. */
6417 /* Try to perform the conversion. */
6419 LOOKUP_NORMAL);
6420 /* Free all the conversions we allocated. */
6424 }
6426 /* Convert EXPR to TYPE. Return the converted expression.
6428 Note that we allow bad conversions here because by the time we get to
6429 this point we are committed to doing the conversion. If we end up
6430 doing a bad conversion, convert_like will complain. */
6432 tree
6434 {
6441 /* Get the high-water mark for the CONVERSION_OBSTACK. */
6446 LOOKUP_NORMAL);
6448 {
6451 }
6453 {
6454 /* In a template, we are only concerned about determining the
6455 type of non-dependent expressions, so we do not have to
6456 perform the actual conversion. */
6459 }
6460 else
6463 /* Free all the conversions we allocated. */
6467 }
6469 /* Convert EXPR to TYPE (as a direct-initialization) if that is
6470 permitted. If the conversion is valid, the converted expression is
6471 returned. Otherwise, NULL_TREE is returned, except in the case
6472 that TYPE is a class type; in that case, an error is issued. If
6473 C_CAST_P is true, then this direction initialization is taking
6474 place as part of a static_cast being attempted as part of a C-style
6475 cast. */
6477 tree
6479 tree expr,
6481 {
6487 /* [dcl.init]
6489 If the destination type is a (possibly cv-qualified) class type:
6491 -- If the initialization is direct-initialization ...,
6492 constructors are considered. ... If no constructor applies, or
6493 the overload resolution is ambiguous, the initialization is
6494 ill-formed. */
6496 {
6501 }
6503 /* Get the high-water mark for the CONVERSION_OBSTACK. */
6507 c_cast_p,
6508 LOOKUP_NORMAL);
6511 else
6514 c_cast_p);
6516 /* Free all the conversions we allocated. */
6520 }
6522 /* DECL is a VAR_DECL whose type is a REFERENCE_TYPE. The reference
6523 is being bound to a temporary. Create and return a new VAR_DECL
6524 with the indicated TYPE; this variable will store the value to
6525 which the reference is bound. */
6527 tree
6529 {
6530 tree var;
6532 /* Create the variable. */
6535 /* Register the variable. */
6537 {
6538 /* Namespace-scope or local static; give it a mangled name. */
6539 tree name;
6546 }
6547 else
6548 /* Create a new cleanup level if necessary. */
6552 }
6554 /* Convert EXPR to the indicated reference TYPE, in a way suitable for
6555 initializing a variable of that TYPE. If DECL is non-NULL, it is
6556 the VAR_DECL being initialized with the EXPR. (In that case, the
6557 type of DECL will be TYPE.) If DECL is non-NULL, then CLEANUP must
6558 also be non-NULL, and with *CLEANUP initialized to NULL. Upon
6559 return, if *CLEANUP is no longer NULL, it will be an expression
6560 that should be pushed as a cleanup after the returned expression
6561 is used to initialize DECL.
6563 Return the converted expression. */
6565 tree
6567 {
6574 /* Get the high-water mark for the CONVERSION_OBSTACK. */
6579 {
6585 else
6590 }
6592 /* If DECL is non-NULL, then this special rule applies:
6594 [class.temporary]
6596 The temporary to which the reference is bound or the temporary
6597 that is the complete object to which the reference is bound
6598 persists for the lifetime of the reference.
6600 The temporaries created during the evaluation of the expression
6601 initializing the reference, except the temporary to which the
6602 reference is bound, are destroyed at the end of the
6603 full-expression in which they are created.
6605 In that case, we store the converted expression into a new
6606 VAR_DECL in a new scope.
6608 However, we want to be careful not to create temporaries when
6609 they are not required. For example, given:
6611 struct B {};
6612 struct D : public B {};
6613 D f();
6614 const B& b = f();
6616 there is no need to copy the return value from "f"; we can just
6617 extend its lifetime. Similarly, given:
6619 struct S {};
6620 struct T { operator S(); };
6621 T t;
6622 const S& s = t;
6624 we can extend the lifetime of the return value of the conversion
6625 operator. */
6628 {
6629 tree var;
6630 tree base_conv_type;
6632 /* Skip over the REF_BIND. */
6634 /* If the next conversion is a BASE_CONV, skip that too -- but
6635 remember that the conversion was required. */
6637 {
6642 }
6643 else
6645 /* Perform the remainder of the conversion. */
6653 else
6654 {
6656 {
6657 tree init;
6658 tree type;
6660 /* Create the temporary variable. */
6664 /* If the rvalue is the result of a function call it will be
6665 a TARGET_EXPR. If it is some other construct (such as a
6666 member access expression where the underlying object is
6667 itself the result of a function call), turn it into a
6668 TARGET_EXPR here. It is important that EXPR be a
6669 TARGET_EXPR below since otherwise the INIT_EXPR will
6670 attempt to make a bitwise copy of EXPR to initialize
6671 VAR. */
6674 /* Create the INIT_EXPR that will initialize the temporary
6675 variable. */
6678 {
6682 /* We must be careful to destroy the temporary only
6683 after its initialization has taken place. If the
6684 initialization throws an exception, then the
6685 destructor should not be run. We cannot simply
6686 transform INIT into something like:
6688 (INIT, ({ CLEANUP_STMT; }))
6690 because emit_local_var always treats the
6691 initializer as a full-expression. Thus, the
6692 destructor would run too early; it would run at the
6693 end of initializing the reference variable, rather
6694 than at the end of the block enclosing the
6695 reference variable.
6697 The solution is to pass back a cleanup expression
6698 which the caller is responsible for attaching to
6699 the statement tree. */
6700 }
6701 else
6702 {
6706 static_aggregates);
6707 }
6708 /* Use its address to initialize the reference variable. */
6716 }
6717 else
6718 /* Take the address of EXPR. */
6720 /* If a BASE_CONV was required, perform it now. */
6722 expr = (perform_implicit_conversion
6725 }
6726 }
6727 else
6728 /* Perform the conversion. */
6731 /* Free all the conversions we allocated. */
6735 }