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;
255 /* Fix up the representation of -1 if appropriate. */
256 force_fit_type (expr, 0);
260 if (INTEGRAL_CODE_P (form))
262 if (TYPE_PRECISION (intype) == POINTER_SIZE)
263 return build1 (CONVERT_EXPR, type, expr);
264 expr = cp_convert (c_common_type_for_size (POINTER_SIZE, 0), expr);
265 /* Modes may be different but sizes should be the same. */
266 if (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr)))
267 != GET_MODE_SIZE (TYPE_MODE (type)))
268 /* There is supposed to be some integral type
269 that is the same width as a pointer. */
271 return convert_to_pointer (type, expr);
274 if (type_unknown_p (expr))
275 return instantiate_type (type, expr, tf_error | tf_warning);
277 error ("cannot convert `%E' from type `%T' to type `%T'",
279 return error_mark_node;
282 /* Like convert, except permit conversions to take place which
283 are not normally allowed due to access restrictions
284 (such as conversion from sub-type to private super-type). */
287 convert_to_pointer_force (type, expr)
290 register tree intype = TREE_TYPE (expr);
291 register enum tree_code form = TREE_CODE (intype);
293 if (form == POINTER_TYPE)
295 intype = TYPE_MAIN_VARIANT (intype);
297 if (TYPE_MAIN_VARIANT (type) != intype
298 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
299 && IS_AGGR_TYPE (TREE_TYPE (type))
300 && IS_AGGR_TYPE (TREE_TYPE (intype))
301 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
303 enum tree_code code = PLUS_EXPR;
306 binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
310 binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
314 if (binfo == error_mark_node)
315 return error_mark_node;
318 expr = build_base_path (code, expr, binfo, 0);
319 /* Add any qualifier conversions. */
320 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)),
323 expr = build1 (NOP_EXPR, type, expr);
324 TREE_CONSTANT (expr) =
325 TREE_CONSTANT (TREE_OPERAND (expr, 0));
333 return cp_convert_to_pointer (type, expr, 1);
336 /* We are passing something to a function which requires a reference.
337 The type we are interested in is in TYPE. The initial
338 value we have to begin with is in ARG.
340 FLAGS controls how we manage access checking.
341 DIRECT_BIND in FLAGS controls how any temporaries are generated.
342 If DIRECT_BIND is set, DECL is the reference we're binding to. */
345 build_up_reference (type, arg, flags, decl)
346 tree type, arg, decl;
350 tree argtype = TREE_TYPE (arg);
351 tree target_type = TREE_TYPE (type);
352 tree stmt_expr = NULL_TREE;
354 my_friendly_assert (TREE_CODE (type) == REFERENCE_TYPE, 187);
356 if ((flags & DIRECT_BIND) && ! real_lvalue_p (arg))
358 /* Create a new temporary variable. We can't just use a TARGET_EXPR
359 here because it needs to live as long as DECL. */
362 arg = build_decl (VAR_DECL, NULL_TREE, argtype);
363 DECL_ARTIFICIAL (arg) = 1;
365 TREE_STATIC (arg) = TREE_STATIC (decl);
367 if (TREE_STATIC (decl))
369 /* Namespace-scope or local static; give it a mangled name. */
370 tree name = mangle_ref_init_variable (decl);
371 DECL_NAME (arg) = name;
372 SET_DECL_ASSEMBLER_NAME (arg, name);
373 arg = pushdecl_top_level (arg);
377 /* Automatic; make sure we handle the cleanup properly. */
378 maybe_push_cleanup_level (argtype);
379 arg = pushdecl (arg);
382 /* Process the initializer for the declaration. */
383 DECL_INITIAL (arg) = targ;
384 cp_finish_decl (arg, targ, NULL_TREE,
385 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
387 else if (!(flags & DIRECT_BIND) && ! lvalue_p (arg))
388 return get_target_expr (arg);
390 /* If we had a way to wrap this up, and say, if we ever needed its
391 address, transform all occurrences of the register, into a memory
392 reference we could win better. */
393 rval = build_unary_op (ADDR_EXPR, arg, 1);
394 if (rval == error_mark_node)
395 return error_mark_node;
397 if ((flags & LOOKUP_PROTECT)
398 && TYPE_MAIN_VARIANT (argtype) != TYPE_MAIN_VARIANT (target_type)
399 && IS_AGGR_TYPE (argtype)
400 && IS_AGGR_TYPE (target_type))
402 /* We go through lookup_base for the access control. */
403 tree binfo = lookup_base (argtype, target_type, ba_check, NULL);
404 if (binfo == error_mark_node)
405 return error_mark_node;
406 if (binfo == NULL_TREE)
407 return error_not_base_type (target_type, argtype);
408 rval = build_base_path (PLUS_EXPR, rval, binfo, 1);
412 = convert_to_pointer_force (build_pointer_type (target_type), rval);
413 rval = build1 (NOP_EXPR, type, rval);
414 TREE_CONSTANT (rval) = TREE_CONSTANT (TREE_OPERAND (rval, 0));
416 /* If we created and initialized a new temporary variable, add the
417 representation of that initialization to the RVAL. */
419 rval = build (COMPOUND_EXPR, TREE_TYPE (rval), stmt_expr, rval);
421 /* And return the result. */
425 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
426 INTYPE is the original rvalue type and DECL is an optional _DECL node
429 [dcl.init.ref] says that if an rvalue is used to
430 initialize a reference, then the reference must be to a
431 non-volatile const type. */
434 warn_ref_binding (reftype, intype, decl)
435 tree reftype, intype, decl;
437 tree ttl = TREE_TYPE (reftype);
439 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl))
443 if (CP_TYPE_VOLATILE_P (ttl) && decl)
444 msg = "initialization of volatile reference type `%#T' from rvalue of type `%T'";
445 else if (CP_TYPE_VOLATILE_P (ttl))
446 msg = "conversion to volatile reference type `%#T' from rvalue of type `%T'";
448 msg = "initialization of non-const reference type `%#T' from rvalue of type `%T'";
450 msg = "conversion to non-const reference type `%#T' from rvalue of type `%T'";
452 pedwarn (msg, reftype, intype);
456 /* For C++: Only need to do one-level references, but cannot
457 get tripped up on signed/unsigned differences.
459 DECL is either NULL_TREE or the _DECL node for a reference that is being
460 initialized. It can be error_mark_node if we don't know the _DECL but
461 we know it's an initialization. */
464 convert_to_reference (reftype, expr, convtype, flags, decl)
469 register tree type = TYPE_MAIN_VARIANT (TREE_TYPE (reftype));
470 register tree intype = TREE_TYPE (expr);
471 tree rval = NULL_TREE;
472 tree rval_as_conversion = NULL_TREE;
475 if (TREE_CODE (type) == FUNCTION_TYPE && intype == unknown_type_node)
477 expr = instantiate_type (type, expr,
478 (flags & LOOKUP_COMPLAIN)
479 ? tf_error | tf_warning : tf_none);
480 if (expr == error_mark_node)
481 return error_mark_node;
483 intype = TREE_TYPE (expr);
486 my_friendly_assert (TREE_CODE (intype) != REFERENCE_TYPE, 364);
488 intype = TYPE_MAIN_VARIANT (intype);
490 i = comp_target_types (type, intype, 0);
492 if (i <= 0 && (convtype & CONV_IMPLICIT) && IS_AGGR_TYPE (intype)
493 && ! (flags & LOOKUP_NO_CONVERSION))
495 /* Look for a user-defined conversion to lvalue that we can use. */
498 = build_type_conversion (reftype, expr, 1);
500 if (rval_as_conversion && rval_as_conversion != error_mark_node
501 && real_lvalue_p (rval_as_conversion))
503 expr = rval_as_conversion;
504 rval_as_conversion = NULL_TREE;
510 if (((convtype & CONV_STATIC) && i == -1)
511 || ((convtype & CONV_IMPLICIT) && i == 1))
513 if (flags & LOOKUP_COMPLAIN)
515 tree ttl = TREE_TYPE (reftype);
516 tree ttr = lvalue_type (expr);
518 if (! real_lvalue_p (expr))
519 warn_ref_binding (reftype, intype, decl);
521 if (! (convtype & CONV_CONST)
522 && !at_least_as_qualified_p (ttl, ttr))
523 pedwarn ("conversion from `%T' to `%T' discards qualifiers",
527 return build_up_reference (reftype, expr, flags, decl);
529 else if ((convtype & CONV_REINTERPRET) && lvalue_p (expr))
531 /* When casting an lvalue to a reference type, just convert into
532 a pointer to the new type and deference it. This is allowed
533 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
534 should be done directly (jason). (int &)ri ---> *(int*)&ri */
536 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
538 if (TREE_CODE (intype) == POINTER_TYPE
539 && (comptypes (TREE_TYPE (intype), type,
540 COMPARE_BASE | COMPARE_RELAXED )))
541 warning ("casting `%T' to `%T' does not dereference pointer",
544 rval = build_unary_op (ADDR_EXPR, expr, 0);
545 if (rval != error_mark_node)
546 rval = convert_force (build_pointer_type (TREE_TYPE (reftype)),
548 if (rval != error_mark_node)
549 rval = build1 (NOP_EXPR, reftype, rval);
553 rval = convert_for_initialization (NULL_TREE, type, expr, flags,
555 if (rval == NULL_TREE || rval == error_mark_node)
557 warn_ref_binding (reftype, intype, decl);
558 rval = build_up_reference (reftype, rval, flags, decl);
563 /* If we found a way to convert earlier, then use it. */
567 my_friendly_assert (TREE_CODE (intype) != OFFSET_TYPE, 189);
569 if (flags & LOOKUP_COMPLAIN)
570 error ("cannot convert type `%T' to type `%T'", intype, reftype);
572 if (flags & LOOKUP_SPECULATIVELY)
575 return error_mark_node;
578 /* We are using a reference VAL for its value. Bash that reference all the
579 way down to its lowest form. */
582 convert_from_reference (val)
585 tree type = TREE_TYPE (val);
587 if (TREE_CODE (type) == OFFSET_TYPE)
588 type = TREE_TYPE (type);
589 if (TREE_CODE (type) == REFERENCE_TYPE)
590 return build_indirect_ref (val, NULL);
594 /* Implicitly convert the lvalue EXPR to another lvalue of type TOTYPE,
595 preserving cv-qualification. */
598 convert_lvalue (totype, expr)
601 totype = cp_build_qualified_type (totype, TYPE_QUALS (TREE_TYPE (expr)));
602 totype = build_reference_type (totype);
603 expr = convert_to_reference (totype, expr, CONV_IMPLICIT, LOOKUP_NORMAL,
605 return convert_from_reference (expr);
608 /* C++ conversions, preference to static cast conversions. */
611 cp_convert (type, expr)
614 return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL);
619 FLAGS indicates how we should behave. */
622 ocp_convert (type, expr, convtype, flags)
626 register tree e = expr;
627 register enum tree_code code = TREE_CODE (type);
629 if (e == error_mark_node
630 || TREE_TYPE (e) == error_mark_node)
631 return error_mark_node;
633 complete_type (type);
634 complete_type (TREE_TYPE (expr));
636 e = decl_constant_value (e);
638 if (IS_AGGR_TYPE (type) && (convtype & CONV_FORCE_TEMP)
639 /* Some internal structures (vtable_entry_type, sigtbl_ptr_type)
640 don't go through finish_struct, so they don't have the synthesized
641 constructors. So don't force a temporary. */
642 && TYPE_HAS_CONSTRUCTOR (type))
643 /* We need a new temporary; don't take this shortcut. */;
644 else if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (e)))
646 if (same_type_p (type, TREE_TYPE (e)))
647 /* The call to fold will not always remove the NOP_EXPR as
648 might be expected, since if one of the types is a typedef;
649 the comparsion in fold is just equality of pointers, not a
650 call to comptypes. We don't call fold in this case because
651 that can result in infinite recursion; fold will call
652 convert, which will call ocp_convert, etc. */
654 /* For complex data types, we need to perform componentwise
656 else if (TREE_CODE (type) == COMPLEX_TYPE)
657 return fold (convert_to_complex (type, e));
659 return fold (build1 (NOP_EXPR, type, e));
662 if (code == VOID_TYPE && (convtype & CONV_STATIC))
664 e = convert_to_void (e, /*implicit=*/NULL);
668 /* Just convert to the type of the member. */
669 if (code == OFFSET_TYPE)
671 type = TREE_TYPE (type);
672 code = TREE_CODE (type);
675 if (TREE_CODE (e) == OFFSET_REF)
676 e = resolve_offset_ref (e);
678 if (INTEGRAL_CODE_P (code))
680 tree intype = TREE_TYPE (e);
681 /* enum = enum, enum = int, enum = float, (enum)pointer are all
683 if (TREE_CODE (type) == ENUMERAL_TYPE
684 && ((ARITHMETIC_TYPE_P (intype) && ! (convtype & CONV_STATIC))
685 || (TREE_CODE (intype) == POINTER_TYPE)))
687 pedwarn ("conversion from `%#T' to `%#T'", intype, type);
689 if (flag_pedantic_errors)
690 return error_mark_node;
692 if (IS_AGGR_TYPE (intype))
695 rval = build_type_conversion (type, e, 1);
698 if (flags & LOOKUP_COMPLAIN)
699 error ("`%#T' used where a `%T' was expected", intype, type);
700 if (flags & LOOKUP_SPECULATIVELY)
702 return error_mark_node;
704 if (code == BOOLEAN_TYPE)
708 /* Common Ada/Pascal programmer's mistake. We always warn
709 about this since it is so bad. */
710 if (TREE_CODE (expr) == FUNCTION_DECL)
712 else if (TREE_CODE (expr) == ADDR_EXPR
713 && TREE_CODE (TREE_OPERAND (expr, 0)) == FUNCTION_DECL)
714 fn = TREE_OPERAND (expr, 0);
715 if (fn && !DECL_WEAK (fn))
716 warning ("the address of `%D', will always be `true'", fn);
717 return cp_truthvalue_conversion (e);
719 return fold (convert_to_integer (type, e));
721 if (code == POINTER_TYPE || code == REFERENCE_TYPE
722 || TYPE_PTRMEMFUNC_P (type))
723 return fold (cp_convert_to_pointer (type, e, 0));
724 if (code == VECTOR_TYPE)
725 return fold (convert_to_vector (type, e));
726 if (code == REAL_TYPE || code == COMPLEX_TYPE)
728 if (IS_AGGR_TYPE (TREE_TYPE (e)))
731 rval = build_type_conversion (type, e, 1);
735 if (flags & LOOKUP_COMPLAIN)
736 error ("`%#T' used where a floating point value was expected",
739 if (code == REAL_TYPE)
740 return fold (convert_to_real (type, e));
741 else if (code == COMPLEX_TYPE)
742 return fold (convert_to_complex (type, e));
745 /* New C++ semantics: since assignment is now based on
746 memberwise copying, if the rhs type is derived from the
747 lhs type, then we may still do a conversion. */
748 if (IS_AGGR_TYPE_CODE (code))
750 tree dtype = TREE_TYPE (e);
751 tree ctor = NULL_TREE;
753 dtype = TYPE_MAIN_VARIANT (dtype);
755 /* Conversion between aggregate types. New C++ semantics allow
756 objects of derived type to be cast to objects of base type.
757 Old semantics only allowed this between pointers.
759 There may be some ambiguity between using a constructor
760 vs. using a type conversion operator when both apply. */
764 if (abstract_virtuals_error (NULL_TREE, type))
765 return error_mark_node;
767 if ((flags & LOOKUP_ONLYCONVERTING)
768 && ! (IS_AGGR_TYPE (dtype) && DERIVED_FROM_P (type, dtype)))
769 /* For copy-initialization, first we create a temp of the proper type
770 with a user-defined conversion sequence, then we direct-initialize
771 the target with the temp (see [dcl.init]). */
772 ctor = build_user_type_conversion (type, ctor, flags);
774 ctor = build_method_call (NULL_TREE,
775 complete_ctor_identifier,
776 build_tree_list (NULL_TREE, ctor),
777 TYPE_BINFO (type), flags);
779 return build_cplus_new (type, ctor);
782 /* If TYPE or TREE_TYPE (E) is not on the permanent_obstack,
783 then it won't be hashed and hence compare as not equal,
785 if (code == ARRAY_TYPE
786 && TREE_TYPE (TREE_TYPE (e)) == TREE_TYPE (type)
787 && index_type_equal (TYPE_DOMAIN (TREE_TYPE (e)), TYPE_DOMAIN (type)))
790 if (flags & LOOKUP_COMPLAIN)
791 error ("conversion from `%T' to non-scalar type `%T' requested",
792 TREE_TYPE (expr), type);
793 if (flags & LOOKUP_SPECULATIVELY)
795 return error_mark_node;
798 /* When an expression is used in a void context, its value is discarded and
799 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
800 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
801 in a void context. The C++ standard does not define what an `access' to an
802 object is, but there is reason to beleive that it is the lvalue to rvalue
803 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
804 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
805 indicates that volatile semantics should be the same between C and C++
806 where ever possible. C leaves it implementation defined as to what
807 constitutes an access to a volatile. So, we interpret `*vp' as a read of
808 the volatile object `vp' points to, unless that is an incomplete type. For
809 volatile references we do not do this interpretation, because that would
810 make it impossible to ignore the reference return value from functions. We
811 issue warnings in the confusing cases.
813 IMPLICIT is tells us the context of an implicit void conversion. */
816 convert_to_void (expr, implicit)
818 const char *implicit;
820 if (expr == error_mark_node
821 || TREE_TYPE (expr) == error_mark_node)
822 return error_mark_node;
823 if (!TREE_TYPE (expr))
825 if (VOID_TYPE_P (TREE_TYPE (expr)))
827 switch (TREE_CODE (expr))
831 /* The two parts of a cond expr might be separate lvalues. */
832 tree op1 = TREE_OPERAND (expr,1);
833 tree op2 = TREE_OPERAND (expr,2);
834 tree new_op1 = convert_to_void (op1, implicit);
835 tree new_op2 = convert_to_void (op2, implicit);
837 expr = build (COND_EXPR, TREE_TYPE (new_op1),
838 TREE_OPERAND (expr, 0), new_op1, new_op2);
844 /* The second part of a compound expr contains the value. */
845 tree op1 = TREE_OPERAND (expr,1);
846 tree new_op1 = convert_to_void (op1, implicit);
850 tree t = build (COMPOUND_EXPR, TREE_TYPE (new_op1),
851 TREE_OPERAND (expr, 0), new_op1);
852 TREE_SIDE_EFFECTS (t) = TREE_SIDE_EFFECTS (expr);
853 TREE_NO_UNUSED_WARNING (t) = TREE_NO_UNUSED_WARNING (expr);
860 case NON_LVALUE_EXPR:
862 /* These have already decayed to rvalue. */
865 case CALL_EXPR: /* we have a special meaning for volatile void fn() */
870 tree type = TREE_TYPE (expr);
871 int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
873 int is_volatile = TYPE_VOLATILE (type);
874 int is_complete = COMPLETE_TYPE_P (complete_type (type));
876 if (is_volatile && !is_complete)
877 warning ("object of incomplete type `%T' will not be accessed in %s",
878 type, implicit ? implicit : "void context");
879 else if (is_reference && is_volatile)
880 warning ("object of type `%T' will not be accessed in %s",
881 TREE_TYPE (TREE_OPERAND (expr, 0)),
882 implicit ? implicit : "void context");
883 if (is_reference || !is_volatile || !is_complete)
884 expr = TREE_OPERAND (expr, 0);
891 /* External variables might be incomplete. */
892 tree type = TREE_TYPE (expr);
893 int is_complete = COMPLETE_TYPE_P (complete_type (type));
895 if (TYPE_VOLATILE (type) && !is_complete)
896 warning ("object `%E' of incomplete type `%T' will not be accessed in %s",
897 expr, type, implicit ? implicit : "void context");
902 expr = resolve_offset_ref (expr);
910 if (TREE_CODE (probe) == ADDR_EXPR)
911 probe = TREE_OPERAND (expr, 0);
912 if (type_unknown_p (probe))
914 /* [over.over] enumerates the places where we can take the address
915 of an overloaded function, and this is not one of them. */
916 pedwarn ("%s cannot resolve address of overloaded function",
917 implicit ? implicit : "void cast");
919 else if (implicit && probe == expr && is_overloaded_fn (probe))
920 /* Only warn when there is no &. */
921 warning ("%s is a reference, not call, to function `%E'",
925 if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
927 /* FIXME: This is where we should check for expressions with no
928 effects. At the moment we do that in both build_x_component_expr
929 and expand_expr_stmt -- inconsistently too. For the moment
930 leave implicit void conversions unadorned so that expand_expr_stmt
931 has a chance of detecting some of the cases. */
933 expr = build1 (CONVERT_EXPR, void_type_node, expr);
938 /* Create an expression whose value is that of EXPR,
939 converted to type TYPE. The TREE_TYPE of the value
940 is always TYPE. This function implements all reasonable
941 conversions; callers should filter out those that are
942 not permitted by the language being compiled.
944 Most of this routine is from build_reinterpret_cast.
946 The backend cannot call cp_convert (what was convert) because
947 conversions to/from basetypes may involve memory references
948 (vbases) and adding or subtracting small values (multiple
949 inheritance), but it calls convert from the constant folding code
950 on subtrees of already built trees after it has ripped them apart.
952 Also, if we ever support range variables, we'll probably also have to
953 do a little bit more work. */
961 if (type == error_mark_node || expr == error_mark_node)
962 return error_mark_node;
964 intype = TREE_TYPE (expr);
966 if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype))
968 expr = decl_constant_value (expr);
969 return fold (build1 (NOP_EXPR, type, expr));
972 return ocp_convert (type, expr, CONV_OLD_CONVERT,
973 LOOKUP_NORMAL|LOOKUP_NO_CONVERSION);
976 /* Like cp_convert, except permit conversions to take place which
977 are not normally allowed due to access restrictions
978 (such as conversion from sub-type to private super-type). */
981 convert_force (type, expr, convtype)
986 register tree e = expr;
987 register enum tree_code code = TREE_CODE (type);
989 if (code == REFERENCE_TYPE)
990 return fold (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN,
992 else if (TREE_CODE (TREE_TYPE (e)) == REFERENCE_TYPE)
993 e = convert_from_reference (e);
995 if (code == POINTER_TYPE)
996 return fold (convert_to_pointer_force (type, e));
998 /* From typeck.c convert_for_assignment */
999 if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR
1000 && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE
1001 && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE)
1002 || integer_zerop (e)
1003 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e)))
1004 && TYPE_PTRMEMFUNC_P (type))
1006 /* compatible pointer to member functions. */
1007 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1);
1010 return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL);
1013 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1014 exists, return the attempted conversion. This may
1015 return ERROR_MARK_NODE if the conversion is not
1016 allowed (references private members, etc).
1017 If no conversion exists, NULL_TREE is returned.
1019 If (FOR_SURE & 1) is non-zero, then we allow this type conversion
1020 to take place immediately. Otherwise, we build a SAVE_EXPR
1021 which can be evaluated if the results are ever needed.
1023 Changes to this functions should be mirrored in user_harshness.
1025 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1026 object parameter, or by the second standard conversion sequence if
1027 that doesn't do it. This will probably wait for an overloading rewrite.
1031 build_type_conversion (xtype, expr, for_sure)
1035 /* C++: check to see if we can convert this aggregate type
1036 into the required type. */
1037 return build_user_type_conversion
1038 (xtype, expr, for_sure ? LOOKUP_NORMAL : 0);
1041 /* Convert the given EXPR to one of a group of types suitable for use in an
1042 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1043 which indicates which types are suitable. If COMPLAIN is 1, complain
1044 about ambiguity; otherwise, the caller will deal with it. */
1047 build_expr_type_conversion (desires, expr, complain)
1052 tree basetype = TREE_TYPE (expr);
1053 tree conv = NULL_TREE;
1054 tree winner = NULL_TREE;
1056 if (expr == null_node
1057 && (desires & WANT_INT)
1058 && !(desires & WANT_NULL))
1059 warning ("converting NULL to non-pointer type");
1061 if (TREE_CODE (expr) == OFFSET_REF)
1062 expr = resolve_offset_ref (expr);
1063 expr = convert_from_reference (expr);
1064 basetype = TREE_TYPE (expr);
1066 if (basetype == error_mark_node)
1067 return error_mark_node;
1069 if (! IS_AGGR_TYPE (basetype))
1070 switch (TREE_CODE (basetype))
1073 if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
1075 /* else fall through... */
1078 return (desires & WANT_INT) ? expr : NULL_TREE;
1080 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1082 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1084 return (desires & WANT_POINTER) ? expr : NULL_TREE;
1088 return (desires & WANT_POINTER) ? default_conversion (expr)
1094 /* The code for conversions from class type is currently only used for
1095 delete expressions. Other expressions are handled by build_new_op. */
1097 if (! TYPE_HAS_CONVERSION (basetype))
1100 for (conv = lookup_conversions (basetype); conv; conv = TREE_CHAIN (conv))
1104 tree cand = TREE_VALUE (conv);
1106 if (winner && winner == cand)
1109 candidate = TREE_TYPE (TREE_TYPE (cand));
1110 if (TREE_CODE (candidate) == REFERENCE_TYPE)
1111 candidate = TREE_TYPE (candidate);
1113 switch (TREE_CODE (candidate))
1117 win = (desires & WANT_INT); break;
1119 win = (desires & WANT_ENUM); break;
1121 win = (desires & WANT_FLOAT); break;
1123 win = (desires & WANT_POINTER); break;
1135 error ("ambiguous default type conversion from `%T'",
1137 error (" candidate conversions include `%D' and `%D'",
1140 return error_mark_node;
1149 tree type = TREE_TYPE (TREE_TYPE (winner));
1150 if (TREE_CODE (type) == REFERENCE_TYPE)
1151 type = TREE_TYPE (type);
1152 return build_user_type_conversion (type, expr, LOOKUP_NORMAL);
1158 /* Implements integral promotion (4.1) and float->double promotion. */
1161 type_promotes_to (type)
1166 if (type == error_mark_node)
1167 return error_mark_node;
1169 type_quals = cp_type_quals (type);
1170 type = TYPE_MAIN_VARIANT (type);
1172 /* bool always promotes to int (not unsigned), even if it's the same
1174 if (type == boolean_type_node)
1175 type = integer_type_node;
1177 /* Normally convert enums to int, but convert wide enums to something
1179 else if (TREE_CODE (type) == ENUMERAL_TYPE
1180 || type == wchar_type_node)
1182 int precision = MAX (TYPE_PRECISION (type),
1183 TYPE_PRECISION (integer_type_node));
1184 tree totype = c_common_type_for_size (precision, 0);
1185 if (TREE_UNSIGNED (type)
1186 && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype))
1187 type = c_common_type_for_size (precision, 1);
1191 else if (c_promoting_integer_type_p (type))
1193 /* Retain unsignedness if really not getting bigger. */
1194 if (TREE_UNSIGNED (type)
1195 && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1196 type = unsigned_type_node;
1198 type = integer_type_node;
1200 else if (type == float_type_node)
1201 type = double_type_node;
1203 return cp_build_qualified_type (type, type_quals);
1206 /* The routines below this point are carefully written to conform to
1207 the standard. They use the same terminology, and follow the rules
1208 closely. Although they are used only in pt.c at the moment, they
1209 should presumably be used everywhere in the future. */
1211 /* Attempt to perform qualification conversions on EXPR to convert it
1212 to TYPE. Return the resulting expression, or error_mark_node if
1213 the conversion was impossible. */
1216 perform_qualification_conversions (type, expr)
1220 if (TREE_CODE (type) == POINTER_TYPE
1221 && TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE
1222 && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (TREE_TYPE (expr))))
1223 return build1 (NOP_EXPR, type, expr);
1225 return error_mark_node;