1 /* Language-level data type conversion for GNU C++.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
4 Hacked by Michael Tiemann (tiemann@cygnus.com)
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
24 /* This file contains the functions for converting C expressions
25 to different data types. The only entry point is `convert'.
26 Every language front end must have a `convert' function
27 but what kind of conversions it does will depend on the language. */
38 static tree cp_convert_to_pointer PARAMS ((tree, tree, int));
39 static tree convert_to_pointer_force PARAMS ((tree, tree));
40 static tree build_up_reference PARAMS ((tree, tree, int, tree));
41 static void warn_ref_binding PARAMS ((tree, tree, tree));
43 /* Change of width--truncation and extension of integers or reals--
44 is represented with NOP_EXPR. Proper functioning of many things
45 assumes that no other conversions can be NOP_EXPRs.
47 Conversion between integer and pointer is represented with CONVERT_EXPR.
48 Converting integer to real uses FLOAT_EXPR
49 and real to integer uses FIX_TRUNC_EXPR.
51 Here is a list of all the functions that assume that widening and
52 narrowing is always done with a NOP_EXPR:
53 In convert.c, convert_to_integer.
54 In c-typeck.c, build_binary_op_nodefault (boolean ops),
55 and c_common_truthvalue_conversion.
56 In expr.c: expand_expr, for operands of a MULT_EXPR.
57 In fold-const.c: fold.
58 In tree.c: get_narrower and get_unwidened.
60 C++: in multiple-inheritance, converting between pointers may involve
61 adjusting them by a delta stored within the class definition. */
63 /* Subroutines of `convert'. */
65 /* if converting pointer to pointer
66 if dealing with classes, check for derived->base or vice versa
67 else if dealing with method pointers, delegate
69 else if converting class, pass off to build_type_conversion
70 else try C-style pointer conversion. If FORCE is true then allow
71 conversions via virtual bases (these are permitted by reinterpret_cast,
72 but not static_cast). */
75 cp_convert_to_pointer (type, expr, force)
79 register tree intype = TREE_TYPE (expr);
80 register enum tree_code form;
83 if (IS_AGGR_TYPE (intype))
85 intype = complete_type (intype);
86 if (!COMPLETE_TYPE_P (intype))
88 error ("can't convert from incomplete type `%T' to `%T'",
90 return error_mark_node;
93 rval = build_type_conversion (type, expr, 1);
96 if (rval == error_mark_node)
97 error ("conversion of `%E' from `%T' to `%T' is ambiguous",
103 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
104 if (TREE_CODE (type) == POINTER_TYPE
105 && (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
106 || VOID_TYPE_P (TREE_TYPE (type))))
108 /* Allow an implicit this pointer for pointer to member
110 if (TYPE_PTRMEMFUNC_P (intype))
112 tree fntype = TREE_TYPE (TYPE_PTRMEMFUNC_FN_TYPE (intype));
113 tree decl = maybe_dummy_object (TYPE_METHOD_BASETYPE (fntype), 0);
114 expr = build (OFFSET_REF, fntype, decl, expr);
117 if (TREE_CODE (expr) == OFFSET_REF
118 && TREE_CODE (TREE_TYPE (expr)) == METHOD_TYPE)
119 expr = resolve_offset_ref (expr);
120 if (TREE_CODE (TREE_TYPE (expr)) == METHOD_TYPE)
121 expr = build_addr_func (expr);
122 if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
124 if (TREE_CODE (TREE_TYPE (TREE_TYPE (expr))) == METHOD_TYPE)
125 if (pedantic || warn_pmf2ptr)
126 pedwarn ("converting from `%T' to `%T'", TREE_TYPE (expr),
128 return build1 (NOP_EXPR, type, expr);
130 intype = TREE_TYPE (expr);
133 if (expr == error_mark_node)
134 return error_mark_node;
136 form = TREE_CODE (intype);
138 if (POINTER_TYPE_P (intype))
140 intype = TYPE_MAIN_VARIANT (intype);
142 if (TYPE_MAIN_VARIANT (type) != intype
143 && TREE_CODE (type) == POINTER_TYPE
144 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
145 && IS_AGGR_TYPE (TREE_TYPE (type))
146 && IS_AGGR_TYPE (TREE_TYPE (intype))
147 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
149 enum tree_code code = PLUS_EXPR;
152 /* Try derived to base conversion. */
153 binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
157 /* Try base to derived conversion. */
158 binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
162 if (binfo == error_mark_node)
163 return error_mark_node;
166 expr = build_base_path (code, expr, binfo, 0);
167 /* Add any qualifier conversions. */
168 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)),
171 expr = build1 (NOP_EXPR, type, expr);
172 TREE_CONSTANT (expr) =
173 TREE_CONSTANT (TREE_OPERAND (expr, 0));
179 if (TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
184 enum tree_code code = PLUS_EXPR;
187 b1 = TYPE_OFFSET_BASETYPE (TREE_TYPE (type));
188 b2 = TYPE_OFFSET_BASETYPE (TREE_TYPE (intype));
189 binfo = lookup_base (b1, b2, ba_check, &bk);
192 binfo = lookup_base (b2, b1, ba_check, &bk);
195 if (binfo == error_mark_node)
196 return error_mark_node;
198 if (bk == bk_via_virtual)
201 warning ("pointer to member cast from `%T' to `%T' is via virtual base",
202 TREE_TYPE (intype), TREE_TYPE (type));
205 error ("pointer to member cast from `%T' to `%T' is via virtual base",
206 TREE_TYPE (intype), TREE_TYPE (type));
207 return error_mark_node;
209 /* This is a reinterpret cast, whose result is unspecified.
210 We choose to do nothing. */
211 return build1 (NOP_EXPR, type, expr);
214 if (TREE_CODE (expr) == PTRMEM_CST)
215 expr = cplus_expand_constant (expr);
218 expr = size_binop (code, convert (sizetype, expr),
219 BINFO_OFFSET (binfo));
221 else if (TYPE_PTRMEMFUNC_P (type))
223 error ("cannot convert `%E' from type `%T' to type `%T'",
225 return error_mark_node;
228 rval = build1 (NOP_EXPR, type, expr);
229 TREE_CONSTANT (rval) = TREE_CONSTANT (expr);
232 else if (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype))
233 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0);
234 else if (TYPE_PTRMEMFUNC_P (intype))
236 error ("cannot convert `%E' from type `%T' to type `%T'",
238 return error_mark_node;
241 my_friendly_assert (form != OFFSET_TYPE, 186);
243 if (integer_zerop (expr))
245 if (TYPE_PTRMEMFUNC_P (type))
246 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0);
248 if (TYPE_PTRMEM_P (type))
249 /* A NULL pointer-to-member is represented by -1, not by
251 expr = build_int_2 (-1, -1);
253 expr = build_int_2 (0, 0);
254 TREE_TYPE (expr) = type;
258 if (INTEGRAL_CODE_P (form))
260 if (TYPE_PRECISION (intype) == POINTER_SIZE)
261 return build1 (CONVERT_EXPR, type, expr);
262 expr = cp_convert (c_common_type_for_size (POINTER_SIZE, 0), expr);
263 /* Modes may be different but sizes should be the same. */
264 if (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr)))
265 != GET_MODE_SIZE (TYPE_MODE (type)))
266 /* There is supposed to be some integral type
267 that is the same width as a pointer. */
269 return convert_to_pointer (type, expr);
272 if (type_unknown_p (expr))
273 return instantiate_type (type, expr, tf_error | tf_warning);
275 error ("cannot convert `%E' from type `%T' to type `%T'",
277 return error_mark_node;
280 /* Like convert, except permit conversions to take place which
281 are not normally allowed due to access restrictions
282 (such as conversion from sub-type to private super-type). */
285 convert_to_pointer_force (type, expr)
288 register tree intype = TREE_TYPE (expr);
289 register enum tree_code form = TREE_CODE (intype);
291 if (form == POINTER_TYPE)
293 intype = TYPE_MAIN_VARIANT (intype);
295 if (TYPE_MAIN_VARIANT (type) != intype
296 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
297 && IS_AGGR_TYPE (TREE_TYPE (type))
298 && IS_AGGR_TYPE (TREE_TYPE (intype))
299 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
301 enum tree_code code = PLUS_EXPR;
304 binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
308 binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
312 if (binfo == error_mark_node)
313 return error_mark_node;
316 expr = build_base_path (code, expr, binfo, 0);
317 /* Add any qualifier conversions. */
318 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)),
321 expr = build1 (NOP_EXPR, type, expr);
322 TREE_CONSTANT (expr) =
323 TREE_CONSTANT (TREE_OPERAND (expr, 0));
331 return cp_convert_to_pointer (type, expr, 1);
334 /* We are passing something to a function which requires a reference.
335 The type we are interested in is in TYPE. The initial
336 value we have to begin with is in ARG.
338 FLAGS controls how we manage access checking.
339 DIRECT_BIND in FLAGS controls how any temporaries are generated.
340 If DIRECT_BIND is set, DECL is the reference we're binding to. */
343 build_up_reference (type, arg, flags, decl)
344 tree type, arg, decl;
348 tree argtype = TREE_TYPE (arg);
349 tree target_type = TREE_TYPE (type);
350 tree stmt_expr = NULL_TREE;
352 my_friendly_assert (TREE_CODE (type) == REFERENCE_TYPE, 187);
354 if ((flags & DIRECT_BIND) && ! real_lvalue_p (arg))
356 /* Create a new temporary variable. We can't just use a TARGET_EXPR
357 here because it needs to live as long as DECL. */
360 arg = build_decl (VAR_DECL, NULL_TREE, argtype);
361 DECL_ARTIFICIAL (arg) = 1;
363 TREE_STATIC (arg) = TREE_STATIC (decl);
365 if (TREE_STATIC (decl))
367 /* Namespace-scope or local static; give it a mangled name. */
368 tree name = mangle_ref_init_variable (decl);
369 DECL_NAME (arg) = name;
370 SET_DECL_ASSEMBLER_NAME (arg, name);
371 arg = pushdecl_top_level (arg);
375 /* Automatic; make sure we handle the cleanup properly. */
376 maybe_push_cleanup_level (argtype);
377 arg = pushdecl (arg);
380 /* Process the initializer for the declaration. */
381 DECL_INITIAL (arg) = targ;
382 cp_finish_decl (arg, targ, NULL_TREE,
383 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
385 else if (!(flags & DIRECT_BIND) && ! lvalue_p (arg))
386 return get_target_expr (arg);
388 /* If we had a way to wrap this up, and say, if we ever needed its
389 address, transform all occurrences of the register, into a memory
390 reference we could win better. */
391 rval = build_unary_op (ADDR_EXPR, arg, 1);
392 if (rval == error_mark_node)
393 return error_mark_node;
395 if ((flags & LOOKUP_PROTECT)
396 && TYPE_MAIN_VARIANT (argtype) != TYPE_MAIN_VARIANT (target_type)
397 && IS_AGGR_TYPE (argtype)
398 && IS_AGGR_TYPE (target_type))
400 /* We go through lookup_base for the access control. */
401 tree binfo = lookup_base (argtype, target_type, ba_check, NULL);
402 if (binfo == error_mark_node)
403 return error_mark_node;
404 if (binfo == NULL_TREE)
405 return error_not_base_type (target_type, argtype);
406 rval = build_base_path (PLUS_EXPR, rval, binfo, 1);
410 = convert_to_pointer_force (build_pointer_type (target_type), rval);
411 rval = build1 (NOP_EXPR, type, rval);
412 TREE_CONSTANT (rval) = TREE_CONSTANT (TREE_OPERAND (rval, 0));
414 /* If we created and initialized a new temporary variable, add the
415 representation of that initialization to the RVAL. */
417 rval = build (COMPOUND_EXPR, TREE_TYPE (rval), stmt_expr, rval);
419 /* And return the result. */
423 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
424 INTYPE is the original rvalue type and DECL is an optional _DECL node
427 [dcl.init.ref] says that if an rvalue is used to
428 initialize a reference, then the reference must be to a
429 non-volatile const type. */
432 warn_ref_binding (reftype, intype, decl)
433 tree reftype, intype, decl;
435 tree ttl = TREE_TYPE (reftype);
437 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl))
441 if (CP_TYPE_VOLATILE_P (ttl) && decl)
442 msg = "initialization of volatile reference type `%#T' from rvalue of type `%T'";
443 else if (CP_TYPE_VOLATILE_P (ttl))
444 msg = "conversion to volatile reference type `%#T' from rvalue of type `%T'";
446 msg = "initialization of non-const reference type `%#T' from rvalue of type `%T'";
448 msg = "conversion to non-const reference type `%#T' from rvalue of type `%T'";
450 pedwarn (msg, reftype, intype);
454 /* For C++: Only need to do one-level references, but cannot
455 get tripped up on signed/unsigned differences.
457 DECL is either NULL_TREE or the _DECL node for a reference that is being
458 initialized. It can be error_mark_node if we don't know the _DECL but
459 we know it's an initialization. */
462 convert_to_reference (reftype, expr, convtype, flags, decl)
467 register tree type = TYPE_MAIN_VARIANT (TREE_TYPE (reftype));
468 register tree intype = TREE_TYPE (expr);
469 tree rval = NULL_TREE;
470 tree rval_as_conversion = NULL_TREE;
473 if (TREE_CODE (type) == FUNCTION_TYPE && intype == unknown_type_node)
475 expr = instantiate_type (type, expr,
476 (flags & LOOKUP_COMPLAIN)
477 ? tf_error | tf_warning : tf_none);
478 if (expr == error_mark_node)
479 return error_mark_node;
481 intype = TREE_TYPE (expr);
484 my_friendly_assert (TREE_CODE (intype) != REFERENCE_TYPE, 364);
486 intype = TYPE_MAIN_VARIANT (intype);
488 i = comp_target_types (type, intype, 0);
490 if (i <= 0 && (convtype & CONV_IMPLICIT) && IS_AGGR_TYPE (intype)
491 && ! (flags & LOOKUP_NO_CONVERSION))
493 /* Look for a user-defined conversion to lvalue that we can use. */
496 = build_type_conversion (reftype, expr, 1);
498 if (rval_as_conversion && rval_as_conversion != error_mark_node
499 && real_lvalue_p (rval_as_conversion))
501 expr = rval_as_conversion;
502 rval_as_conversion = NULL_TREE;
508 if (((convtype & CONV_STATIC) && i == -1)
509 || ((convtype & CONV_IMPLICIT) && i == 1))
511 if (flags & LOOKUP_COMPLAIN)
513 tree ttl = TREE_TYPE (reftype);
514 tree ttr = lvalue_type (expr);
516 if (! real_lvalue_p (expr))
517 warn_ref_binding (reftype, intype, decl);
519 if (! (convtype & CONV_CONST)
520 && !at_least_as_qualified_p (ttl, ttr))
521 pedwarn ("conversion from `%T' to `%T' discards qualifiers",
525 return build_up_reference (reftype, expr, flags, decl);
527 else if ((convtype & CONV_REINTERPRET) && lvalue_p (expr))
529 /* When casting an lvalue to a reference type, just convert into
530 a pointer to the new type and deference it. This is allowed
531 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
532 should be done directly (jason). (int &)ri ---> *(int*)&ri */
534 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
536 if (TREE_CODE (intype) == POINTER_TYPE
537 && (comptypes (TREE_TYPE (intype), type,
538 COMPARE_BASE | COMPARE_RELAXED )))
539 warning ("casting `%T' to `%T' does not dereference pointer",
542 rval = build_unary_op (ADDR_EXPR, expr, 0);
543 if (rval != error_mark_node)
544 rval = convert_force (build_pointer_type (TREE_TYPE (reftype)),
546 if (rval != error_mark_node)
547 rval = build1 (NOP_EXPR, reftype, rval);
551 rval = convert_for_initialization (NULL_TREE, type, expr, flags,
553 if (rval == NULL_TREE || rval == error_mark_node)
555 warn_ref_binding (reftype, intype, decl);
556 rval = build_up_reference (reftype, rval, flags, decl);
561 /* If we found a way to convert earlier, then use it. */
565 my_friendly_assert (TREE_CODE (intype) != OFFSET_TYPE, 189);
567 if (flags & LOOKUP_COMPLAIN)
568 error ("cannot convert type `%T' to type `%T'", intype, reftype);
570 if (flags & LOOKUP_SPECULATIVELY)
573 return error_mark_node;
576 /* We are using a reference VAL for its value. Bash that reference all the
577 way down to its lowest form. */
580 convert_from_reference (val)
583 tree type = TREE_TYPE (val);
585 if (TREE_CODE (type) == OFFSET_TYPE)
586 type = TREE_TYPE (type);
587 if (TREE_CODE (type) == REFERENCE_TYPE)
588 return build_indirect_ref (val, NULL);
592 /* Implicitly convert the lvalue EXPR to another lvalue of type TOTYPE,
593 preserving cv-qualification. */
596 convert_lvalue (totype, expr)
599 totype = cp_build_qualified_type (totype, TYPE_QUALS (TREE_TYPE (expr)));
600 totype = build_reference_type (totype);
601 expr = convert_to_reference (totype, expr, CONV_IMPLICIT, LOOKUP_NORMAL,
603 return convert_from_reference (expr);
606 /* C++ conversions, preference to static cast conversions. */
609 cp_convert (type, expr)
612 return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL);
617 FLAGS indicates how we should behave. */
620 ocp_convert (type, expr, convtype, flags)
624 register tree e = expr;
625 register enum tree_code code = TREE_CODE (type);
627 if (e == error_mark_node
628 || TREE_TYPE (e) == error_mark_node)
629 return error_mark_node;
631 complete_type (type);
632 complete_type (TREE_TYPE (expr));
634 e = decl_constant_value (e);
636 if (IS_AGGR_TYPE (type) && (convtype & CONV_FORCE_TEMP)
637 /* Some internal structures (vtable_entry_type, sigtbl_ptr_type)
638 don't go through finish_struct, so they don't have the synthesized
639 constructors. So don't force a temporary. */
640 && TYPE_HAS_CONSTRUCTOR (type))
641 /* We need a new temporary; don't take this shortcut. */;
642 else if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (e)))
644 if (same_type_p (type, TREE_TYPE (e)))
645 /* The call to fold will not always remove the NOP_EXPR as
646 might be expected, since if one of the types is a typedef;
647 the comparsion in fold is just equality of pointers, not a
648 call to comptypes. We don't call fold in this case because
649 that can result in infinite recursion; fold will call
650 convert, which will call ocp_convert, etc. */
652 /* For complex data types, we need to perform componentwise
654 else if (TREE_CODE (type) == COMPLEX_TYPE)
655 return fold (convert_to_complex (type, e));
657 return fold (build1 (NOP_EXPR, type, e));
660 if (code == VOID_TYPE && (convtype & CONV_STATIC))
662 e = convert_to_void (e, /*implicit=*/NULL);
666 /* Just convert to the type of the member. */
667 if (code == OFFSET_TYPE)
669 type = TREE_TYPE (type);
670 code = TREE_CODE (type);
673 if (TREE_CODE (e) == OFFSET_REF)
674 e = resolve_offset_ref (e);
676 if (INTEGRAL_CODE_P (code))
678 tree intype = TREE_TYPE (e);
679 /* enum = enum, enum = int, enum = float, (enum)pointer are all
681 if (TREE_CODE (type) == ENUMERAL_TYPE
682 && ((ARITHMETIC_TYPE_P (intype) && ! (convtype & CONV_STATIC))
683 || (TREE_CODE (intype) == POINTER_TYPE)))
685 pedwarn ("conversion from `%#T' to `%#T'", intype, type);
687 if (flag_pedantic_errors)
688 return error_mark_node;
690 if (IS_AGGR_TYPE (intype))
693 rval = build_type_conversion (type, e, 1);
696 if (flags & LOOKUP_COMPLAIN)
697 error ("`%#T' used where a `%T' was expected", intype, type);
698 if (flags & LOOKUP_SPECULATIVELY)
700 return error_mark_node;
702 if (code == BOOLEAN_TYPE)
706 /* Common Ada/Pascal programmer's mistake. We always warn
707 about this since it is so bad. */
708 if (TREE_CODE (expr) == FUNCTION_DECL)
710 else if (TREE_CODE (expr) == ADDR_EXPR
711 && TREE_CODE (TREE_OPERAND (expr, 0)) == FUNCTION_DECL)
712 fn = TREE_OPERAND (expr, 0);
713 if (fn && !DECL_WEAK (fn))
714 warning ("the address of `%D', will always be `true'", fn);
715 return cp_truthvalue_conversion (e);
717 return fold (convert_to_integer (type, e));
719 if (code == POINTER_TYPE || code == REFERENCE_TYPE
720 || TYPE_PTRMEMFUNC_P (type))
721 return fold (cp_convert_to_pointer (type, e, 0));
722 if (code == VECTOR_TYPE)
723 return fold (convert_to_vector (type, e));
724 if (code == REAL_TYPE || code == COMPLEX_TYPE)
726 if (IS_AGGR_TYPE (TREE_TYPE (e)))
729 rval = build_type_conversion (type, e, 1);
733 if (flags & LOOKUP_COMPLAIN)
734 error ("`%#T' used where a floating point value was expected",
737 if (code == REAL_TYPE)
738 return fold (convert_to_real (type, e));
739 else if (code == COMPLEX_TYPE)
740 return fold (convert_to_complex (type, e));
743 /* New C++ semantics: since assignment is now based on
744 memberwise copying, if the rhs type is derived from the
745 lhs type, then we may still do a conversion. */
746 if (IS_AGGR_TYPE_CODE (code))
748 tree dtype = TREE_TYPE (e);
749 tree ctor = NULL_TREE;
751 dtype = TYPE_MAIN_VARIANT (dtype);
753 /* Conversion between aggregate types. New C++ semantics allow
754 objects of derived type to be cast to objects of base type.
755 Old semantics only allowed this between pointers.
757 There may be some ambiguity between using a constructor
758 vs. using a type conversion operator when both apply. */
762 if (abstract_virtuals_error (NULL_TREE, type))
763 return error_mark_node;
765 if ((flags & LOOKUP_ONLYCONVERTING)
766 && ! (IS_AGGR_TYPE (dtype) && DERIVED_FROM_P (type, dtype)))
767 /* For copy-initialization, first we create a temp of the proper type
768 with a user-defined conversion sequence, then we direct-initialize
769 the target with the temp (see [dcl.init]). */
770 ctor = build_user_type_conversion (type, ctor, flags);
772 ctor = build_method_call (NULL_TREE,
773 complete_ctor_identifier,
774 build_tree_list (NULL_TREE, ctor),
775 TYPE_BINFO (type), flags);
777 return build_cplus_new (type, ctor);
780 /* If TYPE or TREE_TYPE (E) is not on the permanent_obstack,
781 then it won't be hashed and hence compare as not equal,
783 if (code == ARRAY_TYPE
784 && TREE_TYPE (TREE_TYPE (e)) == TREE_TYPE (type)
785 && index_type_equal (TYPE_DOMAIN (TREE_TYPE (e)), TYPE_DOMAIN (type)))
788 if (flags & LOOKUP_COMPLAIN)
789 error ("conversion from `%T' to non-scalar type `%T' requested",
790 TREE_TYPE (expr), type);
791 if (flags & LOOKUP_SPECULATIVELY)
793 return error_mark_node;
796 /* When an expression is used in a void context, its value is discarded and
797 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
798 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
799 in a void context. The C++ standard does not define what an `access' to an
800 object is, but there is reason to beleive that it is the lvalue to rvalue
801 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
802 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
803 indicates that volatile semantics should be the same between C and C++
804 where ever possible. C leaves it implementation defined as to what
805 constitutes an access to a volatile. So, we interpret `*vp' as a read of
806 the volatile object `vp' points to, unless that is an incomplete type. For
807 volatile references we do not do this interpretation, because that would
808 make it impossible to ignore the reference return value from functions. We
809 issue warnings in the confusing cases.
811 IMPLICIT is tells us the context of an implicit void conversion. */
814 convert_to_void (expr, implicit)
816 const char *implicit;
818 if (expr == error_mark_node
819 || TREE_TYPE (expr) == error_mark_node)
820 return error_mark_node;
821 if (!TREE_TYPE (expr))
823 if (VOID_TYPE_P (TREE_TYPE (expr)))
825 switch (TREE_CODE (expr))
829 /* The two parts of a cond expr might be separate lvalues. */
830 tree op1 = TREE_OPERAND (expr,1);
831 tree op2 = TREE_OPERAND (expr,2);
832 tree new_op1 = convert_to_void (op1, implicit);
833 tree new_op2 = convert_to_void (op2, implicit);
835 expr = build (COND_EXPR, TREE_TYPE (new_op1),
836 TREE_OPERAND (expr, 0), new_op1, new_op2);
842 /* The second part of a compound expr contains the value. */
843 tree op1 = TREE_OPERAND (expr,1);
844 tree new_op1 = convert_to_void (op1, implicit);
848 tree t = build (COMPOUND_EXPR, TREE_TYPE (new_op1),
849 TREE_OPERAND (expr, 0), new_op1);
850 TREE_SIDE_EFFECTS (t) = TREE_SIDE_EFFECTS (expr);
851 TREE_NO_UNUSED_WARNING (t) = TREE_NO_UNUSED_WARNING (expr);
858 case NON_LVALUE_EXPR:
860 /* These have already decayed to rvalue. */
863 case CALL_EXPR: /* we have a special meaning for volatile void fn() */
868 tree type = TREE_TYPE (expr);
869 int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
871 int is_volatile = TYPE_VOLATILE (type);
872 int is_complete = COMPLETE_TYPE_P (complete_type (type));
874 if (is_volatile && !is_complete)
875 warning ("object of incomplete type `%T' will not be accessed in %s",
876 type, implicit ? implicit : "void context");
877 else if (is_reference && is_volatile)
878 warning ("object of type `%T' will not be accessed in %s",
879 TREE_TYPE (TREE_OPERAND (expr, 0)),
880 implicit ? implicit : "void context");
881 if (is_reference || !is_volatile || !is_complete)
882 expr = TREE_OPERAND (expr, 0);
889 /* External variables might be incomplete. */
890 tree type = TREE_TYPE (expr);
891 int is_complete = COMPLETE_TYPE_P (complete_type (type));
893 if (TYPE_VOLATILE (type) && !is_complete)
894 warning ("object `%E' of incomplete type `%T' will not be accessed in %s",
895 expr, type, implicit ? implicit : "void context");
900 expr = resolve_offset_ref (expr);
908 if (TREE_CODE (probe) == ADDR_EXPR)
909 probe = TREE_OPERAND (expr, 0);
910 if (type_unknown_p (probe))
912 /* [over.over] enumerates the places where we can take the address
913 of an overloaded function, and this is not one of them. */
914 pedwarn ("%s cannot resolve address of overloaded function",
915 implicit ? implicit : "void cast");
917 else if (implicit && probe == expr && is_overloaded_fn (probe))
918 /* Only warn when there is no &. */
919 warning ("%s is a reference, not call, to function `%E'",
923 if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
925 /* FIXME: This is where we should check for expressions with no
926 effects. At the moment we do that in both build_x_component_expr
927 and expand_expr_stmt -- inconsistently too. For the moment
928 leave implicit void conversions unadorned so that expand_expr_stmt
929 has a chance of detecting some of the cases. */
931 expr = build1 (CONVERT_EXPR, void_type_node, expr);
936 /* Create an expression whose value is that of EXPR,
937 converted to type TYPE. The TREE_TYPE of the value
938 is always TYPE. This function implements all reasonable
939 conversions; callers should filter out those that are
940 not permitted by the language being compiled.
942 Most of this routine is from build_reinterpret_cast.
944 The backend cannot call cp_convert (what was convert) because
945 conversions to/from basetypes may involve memory references
946 (vbases) and adding or subtracting small values (multiple
947 inheritance), but it calls convert from the constant folding code
948 on subtrees of already built trees after it has ripped them apart.
950 Also, if we ever support range variables, we'll probably also have to
951 do a little bit more work. */
959 if (type == error_mark_node || expr == error_mark_node)
960 return error_mark_node;
962 intype = TREE_TYPE (expr);
964 if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype))
966 expr = decl_constant_value (expr);
967 return fold (build1 (NOP_EXPR, type, expr));
970 return ocp_convert (type, expr, CONV_OLD_CONVERT,
971 LOOKUP_NORMAL|LOOKUP_NO_CONVERSION);
974 /* Like cp_convert, except permit conversions to take place which
975 are not normally allowed due to access restrictions
976 (such as conversion from sub-type to private super-type). */
979 convert_force (type, expr, convtype)
984 register tree e = expr;
985 register enum tree_code code = TREE_CODE (type);
987 if (code == REFERENCE_TYPE)
988 return fold (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN,
990 else if (TREE_CODE (TREE_TYPE (e)) == REFERENCE_TYPE)
991 e = convert_from_reference (e);
993 if (code == POINTER_TYPE)
994 return fold (convert_to_pointer_force (type, e));
996 /* From typeck.c convert_for_assignment */
997 if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR
998 && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE
999 && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE)
1000 || integer_zerop (e)
1001 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e)))
1002 && TYPE_PTRMEMFUNC_P (type))
1004 /* compatible pointer to member functions. */
1005 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1);
1008 return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL);
1011 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1012 exists, return the attempted conversion. This may
1013 return ERROR_MARK_NODE if the conversion is not
1014 allowed (references private members, etc).
1015 If no conversion exists, NULL_TREE is returned.
1017 If (FOR_SURE & 1) is non-zero, then we allow this type conversion
1018 to take place immediately. Otherwise, we build a SAVE_EXPR
1019 which can be evaluated if the results are ever needed.
1021 Changes to this functions should be mirrored in user_harshness.
1023 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1024 object parameter, or by the second standard conversion sequence if
1025 that doesn't do it. This will probably wait for an overloading rewrite.
1029 build_type_conversion (xtype, expr, for_sure)
1033 /* C++: check to see if we can convert this aggregate type
1034 into the required type. */
1035 return build_user_type_conversion
1036 (xtype, expr, for_sure ? LOOKUP_NORMAL : 0);
1039 /* Convert the given EXPR to one of a group of types suitable for use in an
1040 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1041 which indicates which types are suitable. If COMPLAIN is 1, complain
1042 about ambiguity; otherwise, the caller will deal with it. */
1045 build_expr_type_conversion (desires, expr, complain)
1050 tree basetype = TREE_TYPE (expr);
1051 tree conv = NULL_TREE;
1052 tree winner = NULL_TREE;
1054 if (expr == null_node
1055 && (desires & WANT_INT)
1056 && !(desires & WANT_NULL))
1057 warning ("converting NULL to non-pointer type");
1059 if (TREE_CODE (expr) == OFFSET_REF)
1060 expr = resolve_offset_ref (expr);
1061 expr = convert_from_reference (expr);
1062 basetype = TREE_TYPE (expr);
1064 if (basetype == error_mark_node)
1065 return error_mark_node;
1067 if (! IS_AGGR_TYPE (basetype))
1068 switch (TREE_CODE (basetype))
1071 if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
1073 /* else fall through... */
1076 return (desires & WANT_INT) ? expr : NULL_TREE;
1078 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1080 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1082 return (desires & WANT_POINTER) ? expr : NULL_TREE;
1086 return (desires & WANT_POINTER) ? default_conversion (expr)
1092 /* The code for conversions from class type is currently only used for
1093 delete expressions. Other expressions are handled by build_new_op. */
1095 if (! TYPE_HAS_CONVERSION (basetype))
1098 for (conv = lookup_conversions (basetype); conv; conv = TREE_CHAIN (conv))
1102 tree cand = TREE_VALUE (conv);
1104 if (winner && winner == cand)
1107 candidate = TREE_TYPE (TREE_TYPE (cand));
1108 if (TREE_CODE (candidate) == REFERENCE_TYPE)
1109 candidate = TREE_TYPE (candidate);
1111 switch (TREE_CODE (candidate))
1115 win = (desires & WANT_INT); break;
1117 win = (desires & WANT_ENUM); break;
1119 win = (desires & WANT_FLOAT); break;
1121 win = (desires & WANT_POINTER); break;
1133 error ("ambiguous default type conversion from `%T'",
1135 error (" candidate conversions include `%D' and `%D'",
1138 return error_mark_node;
1147 tree type = TREE_TYPE (TREE_TYPE (winner));
1148 if (TREE_CODE (type) == REFERENCE_TYPE)
1149 type = TREE_TYPE (type);
1150 return build_user_type_conversion (type, expr, LOOKUP_NORMAL);
1156 /* Implements integral promotion (4.1) and float->double promotion. */
1159 type_promotes_to (type)
1164 if (type == error_mark_node)
1165 return error_mark_node;
1167 type_quals = cp_type_quals (type);
1168 type = TYPE_MAIN_VARIANT (type);
1170 /* bool always promotes to int (not unsigned), even if it's the same
1172 if (type == boolean_type_node)
1173 type = integer_type_node;
1175 /* Normally convert enums to int, but convert wide enums to something
1177 else if (TREE_CODE (type) == ENUMERAL_TYPE
1178 || type == wchar_type_node)
1180 int precision = MAX (TYPE_PRECISION (type),
1181 TYPE_PRECISION (integer_type_node));
1182 tree totype = c_common_type_for_size (precision, 0);
1183 if (TREE_UNSIGNED (type)
1184 && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype))
1185 type = c_common_type_for_size (precision, 1);
1189 else if (c_promoting_integer_type_p (type))
1191 /* Retain unsignedness if really not getting bigger. */
1192 if (TREE_UNSIGNED (type)
1193 && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1194 type = unsigned_type_node;
1196 type = integer_type_node;
1198 else if (type == float_type_node)
1199 type = double_type_node;
1201 return cp_build_qualified_type (type, type_quals);
1204 /* The routines below this point are carefully written to conform to
1205 the standard. They use the same terminology, and follow the rules
1206 closely. Although they are used only in pt.c at the moment, they
1207 should presumably be used everywhere in the future. */
1209 /* Attempt to perform qualification conversions on EXPR to convert it
1210 to TYPE. Return the resulting expression, or error_mark_node if
1211 the conversion was impossible. */
1214 perform_qualification_conversions (type, expr)
1218 if (TREE_CODE (type) == POINTER_TYPE
1219 && TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE
1220 && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (TREE_TYPE (expr))))
1221 return build1 (NOP_EXPR, type, expr);
1223 return error_mark_node;