1 /* Language-level data type conversion for GNU C++.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000 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 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 form = TREE_CODE (intype);
135 if (POINTER_TYPE_P (intype))
137 intype = TYPE_MAIN_VARIANT (intype);
139 if (TYPE_MAIN_VARIANT (type) != intype
140 && TREE_CODE (type) == POINTER_TYPE
141 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
142 && IS_AGGR_TYPE (TREE_TYPE (type))
143 && IS_AGGR_TYPE (TREE_TYPE (intype))
144 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
146 enum tree_code code = PLUS_EXPR;
149 /* Try derived to base conversion. */
150 binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
154 /* Try base to derived conversion. */
155 binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
159 if (binfo == error_mark_node)
160 return error_mark_node;
163 expr = build_base_path (code, expr, binfo, 0);
164 /* Add any qualifier conversions. */
165 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)),
168 expr = build1 (NOP_EXPR, type, expr);
169 TREE_CONSTANT (expr) =
170 TREE_CONSTANT (TREE_OPERAND (expr, 0));
176 if (TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
181 enum tree_code code = PLUS_EXPR;
184 b1 = TYPE_OFFSET_BASETYPE (TREE_TYPE (type));
185 b2 = TYPE_OFFSET_BASETYPE (TREE_TYPE (intype));
186 binfo = lookup_base (b1, b2, ba_check, &bk);
189 binfo = lookup_base (b2, b1, ba_check, &bk);
192 if (binfo == error_mark_node)
193 return error_mark_node;
195 if (bk == bk_via_virtual)
198 warning ("pointer to member cast from `%T' to `%T' is via virtual base",
199 TREE_TYPE (intype), TREE_TYPE (type));
202 error ("pointer to member cast from `%T' to `%T' is via virtual base",
203 TREE_TYPE (intype), TREE_TYPE (type));
204 return error_mark_node;
206 /* This is a reinterpret cast, whose result is unspecified.
207 We choose to do nothing. */
208 return build1 (NOP_EXPR, type, expr);
211 if (TREE_CODE (expr) == PTRMEM_CST)
212 expr = cplus_expand_constant (expr);
215 expr = size_binop (code, convert (sizetype, expr),
216 BINFO_OFFSET (binfo));
218 else if (TYPE_PTRMEMFUNC_P (type))
220 error ("cannot convert `%E' from type `%T' to type `%T'",
222 return error_mark_node;
225 rval = build1 (NOP_EXPR, type, expr);
226 TREE_CONSTANT (rval) = TREE_CONSTANT (expr);
229 else if (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype))
230 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0);
231 else if (TYPE_PTRMEMFUNC_P (intype))
233 error ("cannot convert `%E' from type `%T' to type `%T'",
235 return error_mark_node;
238 my_friendly_assert (form != OFFSET_TYPE, 186);
240 if (integer_zerop (expr))
242 if (TYPE_PTRMEMFUNC_P (type))
243 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0);
245 if (TYPE_PTRMEM_P (type))
246 /* A NULL pointer-to-member is represented by -1, not by
248 expr = build_int_2 (-1, -1);
250 expr = build_int_2 (0, 0);
251 TREE_TYPE (expr) = type;
255 if (INTEGRAL_CODE_P (form))
257 if (TYPE_PRECISION (intype) == POINTER_SIZE)
258 return build1 (CONVERT_EXPR, type, expr);
259 expr = cp_convert (type_for_size (POINTER_SIZE, 0), expr);
260 /* Modes may be different but sizes should be the same. */
261 if (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr)))
262 != GET_MODE_SIZE (TYPE_MODE (type)))
263 /* There is supposed to be some integral type
264 that is the same width as a pointer. */
266 return convert_to_pointer (type, expr);
269 if (type_unknown_p (expr))
270 return instantiate_type (type, expr, itf_complain);
272 error ("cannot convert `%E' from type `%T' to type `%T'",
274 return error_mark_node;
277 /* Like convert, except permit conversions to take place which
278 are not normally allowed due to access restrictions
279 (such as conversion from sub-type to private super-type). */
282 convert_to_pointer_force (type, expr)
285 register tree intype = TREE_TYPE (expr);
286 register enum tree_code form = TREE_CODE (intype);
288 if (integer_zerop (expr))
290 expr = build_int_2 (0, 0);
291 TREE_TYPE (expr) = type;
295 if (form == POINTER_TYPE)
297 intype = TYPE_MAIN_VARIANT (intype);
299 if (TYPE_MAIN_VARIANT (type) != intype
300 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
301 && IS_AGGR_TYPE (TREE_TYPE (type))
302 && IS_AGGR_TYPE (TREE_TYPE (intype))
303 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
305 enum tree_code code = PLUS_EXPR;
308 binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
312 binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
316 if (binfo == error_mark_node)
317 return error_mark_node;
320 expr = build_base_path (code, expr, binfo, 0);
321 /* Add any qualifier conversions. */
322 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)),
325 expr = build1 (NOP_EXPR, type, expr);
326 TREE_CONSTANT (expr) =
327 TREE_CONSTANT (TREE_OPERAND (expr, 0));
335 return cp_convert_to_pointer (type, expr, 1);
338 /* We are passing something to a function which requires a reference.
339 The type we are interested in is in TYPE. The initial
340 value we have to begin with is in ARG.
342 FLAGS controls how we manage access checking.
343 DIRECT_BIND in FLAGS controls how any temporaries are generated.
344 If DIRECT_BIND is set, DECL is the reference we're binding to. */
347 build_up_reference (type, arg, flags, decl)
348 tree type, arg, decl;
352 tree argtype = TREE_TYPE (arg);
353 tree target_type = TREE_TYPE (type);
354 tree stmt_expr = NULL_TREE;
356 my_friendly_assert (TREE_CODE (type) == REFERENCE_TYPE, 187);
358 if ((flags & DIRECT_BIND) && ! real_lvalue_p (arg))
360 /* Create a new temporary variable. We can't just use a TARGET_EXPR
361 here because it needs to live as long as DECL. */
364 arg = build_decl (VAR_DECL, NULL_TREE, argtype);
365 DECL_ARTIFICIAL (arg) = 1;
367 TREE_STATIC (arg) = TREE_STATIC (decl);
369 if (TREE_STATIC (decl))
371 /* Namespace-scope or local static; give it a mangled name. */
372 tree name = mangle_ref_init_variable (decl);
373 DECL_NAME (arg) = name;
374 SET_DECL_ASSEMBLER_NAME (arg, name);
375 arg = pushdecl_top_level (arg);
379 /* Automatic; make sure we handle the cleanup properly. */
380 maybe_push_cleanup_level (argtype);
381 arg = pushdecl (arg);
384 /* Process the initializer for the declaration. */
385 DECL_INITIAL (arg) = targ;
386 cp_finish_decl (arg, targ, NULL_TREE,
387 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
389 else if (!(flags & DIRECT_BIND) && ! lvalue_p (arg))
390 return get_target_expr (arg);
392 /* If we had a way to wrap this up, and say, if we ever needed its
393 address, transform all occurrences of the register, into a memory
394 reference we could win better. */
395 rval = build_unary_op (ADDR_EXPR, arg, 1);
396 if (rval == error_mark_node)
397 return error_mark_node;
399 if ((flags & LOOKUP_PROTECT)
400 && TYPE_MAIN_VARIANT (argtype) != TYPE_MAIN_VARIANT (target_type)
401 && IS_AGGR_TYPE (argtype)
402 && IS_AGGR_TYPE (target_type))
404 /* We go through lookup_base for the access control. */
405 tree binfo = lookup_base (argtype, target_type, ba_check, NULL);
406 if (binfo == error_mark_node)
407 return error_mark_node;
408 if (binfo == NULL_TREE)
409 return error_not_base_type (target_type, argtype);
410 rval = build_base_path (PLUS_EXPR, rval, binfo, 1);
414 = convert_to_pointer_force (build_pointer_type (target_type), rval);
415 rval = build1 (NOP_EXPR, type, rval);
416 TREE_CONSTANT (rval) = TREE_CONSTANT (TREE_OPERAND (rval, 0));
418 /* If we created and initialized a new temporary variable, add the
419 representation of that initialization to the RVAL. */
421 rval = build (COMPOUND_EXPR, TREE_TYPE (rval), stmt_expr, rval);
423 /* And return the result. */
427 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
428 INTYPE is the original rvalue type and DECL is an optional _DECL node
431 [dcl.init.ref] says that if an rvalue is used to
432 initialize a reference, then the reference must be to a
433 non-volatile const type. */
436 warn_ref_binding (reftype, intype, decl)
437 tree reftype, intype, decl;
439 tree ttl = TREE_TYPE (reftype);
441 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl))
445 if (CP_TYPE_VOLATILE_P (ttl) && decl)
446 msg = "initialization of volatile reference type `%#T' from rvalue of type `%T'";
447 else if (CP_TYPE_VOLATILE_P (ttl))
448 msg = "conversion to volatile reference type `%#T' from rvalue of type `%T'";
450 msg = "initialization of non-const reference type `%#T' from rvalue of type `%T'";
452 msg = "conversion to non-const reference type `%#T' from rvalue of type `%T'";
454 pedwarn (msg, reftype, intype);
458 /* For C++: Only need to do one-level references, but cannot
459 get tripped up on signed/unsigned differences.
461 DECL is either NULL_TREE or the _DECL node for a reference that is being
462 initialized. It can be error_mark_node if we don't know the _DECL but
463 we know it's an initialization. */
466 convert_to_reference (reftype, expr, convtype, flags, decl)
471 register tree type = TYPE_MAIN_VARIANT (TREE_TYPE (reftype));
472 register tree intype = TREE_TYPE (expr);
473 tree rval = NULL_TREE;
474 tree rval_as_conversion = NULL_TREE;
477 if (TREE_CODE (type) == FUNCTION_TYPE && intype == unknown_type_node)
479 expr = instantiate_type (type, expr,
480 (flags & LOOKUP_COMPLAIN)
481 ? itf_complain : itf_none);
482 if (expr == error_mark_node)
483 return error_mark_node;
485 intype = TREE_TYPE (expr);
488 if (TREE_CODE (intype) == REFERENCE_TYPE)
489 my_friendly_abort (364);
491 intype = TYPE_MAIN_VARIANT (intype);
493 i = comp_target_types (type, intype, 0);
495 if (i <= 0 && (convtype & CONV_IMPLICIT) && IS_AGGR_TYPE (intype)
496 && ! (flags & LOOKUP_NO_CONVERSION))
498 /* Look for a user-defined conversion to lvalue that we can use. */
501 = build_type_conversion (reftype, expr, 1);
503 if (rval_as_conversion && rval_as_conversion != error_mark_node
504 && real_lvalue_p (rval_as_conversion))
506 expr = rval_as_conversion;
507 rval_as_conversion = NULL_TREE;
513 if (((convtype & CONV_STATIC) && i == -1)
514 || ((convtype & CONV_IMPLICIT) && i == 1))
516 if (flags & LOOKUP_COMPLAIN)
518 tree ttl = TREE_TYPE (reftype);
519 tree ttr = lvalue_type (expr);
521 if (! real_lvalue_p (expr))
522 warn_ref_binding (reftype, intype, decl);
524 if (! (convtype & CONV_CONST)
525 && !at_least_as_qualified_p (ttl, ttr))
526 pedwarn ("conversion from `%T' to `%T' discards qualifiers",
530 return build_up_reference (reftype, expr, flags, decl);
532 else if ((convtype & CONV_REINTERPRET) && lvalue_p (expr))
534 /* When casting an lvalue to a reference type, just convert into
535 a pointer to the new type and deference it. This is allowed
536 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
537 should be done directly (jason). (int &)ri ---> *(int*)&ri */
539 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
541 if (TREE_CODE (intype) == POINTER_TYPE
542 && (comptypes (TREE_TYPE (intype), type,
543 COMPARE_BASE | COMPARE_RELAXED )))
544 warning ("casting `%T' to `%T' does not dereference pointer",
547 rval = build_unary_op (ADDR_EXPR, expr, 0);
548 if (rval != error_mark_node)
549 rval = convert_force (build_pointer_type (TREE_TYPE (reftype)),
551 if (rval != error_mark_node)
552 rval = build1 (NOP_EXPR, reftype, rval);
556 rval = convert_for_initialization (NULL_TREE, type, expr, flags,
558 if (rval == NULL_TREE || rval == error_mark_node)
560 warn_ref_binding (reftype, intype, decl);
561 rval = build_up_reference (reftype, rval, flags, decl);
566 /* If we found a way to convert earlier, then use it. */
570 my_friendly_assert (TREE_CODE (intype) != OFFSET_TYPE, 189);
572 if (flags & LOOKUP_COMPLAIN)
573 error ("cannot convert type `%T' to type `%T'", intype, reftype);
575 if (flags & LOOKUP_SPECULATIVELY)
578 return error_mark_node;
581 /* We are using a reference VAL for its value. Bash that reference all the
582 way down to its lowest form. */
585 convert_from_reference (val)
588 tree type = TREE_TYPE (val);
590 if (TREE_CODE (type) == OFFSET_TYPE)
591 type = TREE_TYPE (type);
592 if (TREE_CODE (type) == REFERENCE_TYPE)
593 return build_indirect_ref (val, NULL);
597 /* Implicitly convert the lvalue EXPR to another lvalue of type TOTYPE,
598 preserving cv-qualification. */
601 convert_lvalue (totype, expr)
604 totype = cp_build_qualified_type (totype, TYPE_QUALS (TREE_TYPE (expr)));
605 totype = build_reference_type (totype);
606 expr = convert_to_reference (totype, expr, CONV_IMPLICIT, LOOKUP_NORMAL,
608 return convert_from_reference (expr);
611 /* C++ conversions, preference to static cast conversions. */
614 cp_convert (type, expr)
617 return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL);
622 FLAGS indicates how we should behave. */
625 ocp_convert (type, expr, convtype, flags)
629 register tree e = expr;
630 register enum tree_code code = TREE_CODE (type);
632 if (e == error_mark_node
633 || TREE_TYPE (e) == error_mark_node)
634 return error_mark_node;
636 complete_type (type);
637 complete_type (TREE_TYPE (expr));
639 e = decl_constant_value (e);
641 if (IS_AGGR_TYPE (type) && (convtype & CONV_FORCE_TEMP)
642 /* Some internal structures (vtable_entry_type, sigtbl_ptr_type)
643 don't go through finish_struct, so they don't have the synthesized
644 constructors. So don't force a temporary. */
645 && TYPE_HAS_CONSTRUCTOR (type))
646 /* We need a new temporary; don't take this shortcut. */;
647 else if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (e)))
649 if (same_type_p (type, TREE_TYPE (e)))
650 /* The call to fold will not always remove the NOP_EXPR as
651 might be expected, since if one of the types is a typedef;
652 the comparsion in fold is just equality of pointers, not a
653 call to comptypes. We don't call fold in this case because
654 that can result in infinite recursion; fold will call
655 convert, which will call ocp_convert, etc. */
657 /* For complex data types, we need to perform componentwise
659 else if (TREE_CODE (type) == COMPLEX_TYPE)
660 return fold (convert_to_complex (type, e));
662 return fold (build1 (NOP_EXPR, type, e));
665 if (code == VOID_TYPE && (convtype & CONV_STATIC))
667 e = convert_to_void (e, /*implicit=*/NULL);
671 /* Just convert to the type of the member. */
672 if (code == OFFSET_TYPE)
674 type = TREE_TYPE (type);
675 code = TREE_CODE (type);
678 if (TREE_CODE (e) == OFFSET_REF)
679 e = resolve_offset_ref (e);
681 if (INTEGRAL_CODE_P (code))
683 tree intype = TREE_TYPE (e);
684 /* enum = enum, enum = int, enum = float, (enum)pointer are all
686 if (TREE_CODE (type) == ENUMERAL_TYPE
687 && ((ARITHMETIC_TYPE_P (intype) && ! (convtype & CONV_STATIC))
688 || (TREE_CODE (intype) == POINTER_TYPE)))
690 pedwarn ("conversion from `%#T' to `%#T'", intype, type);
692 if (flag_pedantic_errors)
693 return error_mark_node;
695 if (IS_AGGR_TYPE (intype))
698 rval = build_type_conversion (type, e, 1);
701 if (flags & LOOKUP_COMPLAIN)
702 error ("`%#T' used where a `%T' was expected", intype, type);
703 if (flags & LOOKUP_SPECULATIVELY)
705 return error_mark_node;
707 if (code == BOOLEAN_TYPE)
711 /* Common Ada/Pascal programmer's mistake. We always warn
712 about this since it is so bad. */
713 if (TREE_CODE (expr) == FUNCTION_DECL)
715 else if (TREE_CODE (expr) == ADDR_EXPR
716 && TREE_CODE (TREE_OPERAND (expr, 0)) == FUNCTION_DECL)
717 fn = TREE_OPERAND (expr, 0);
718 if (fn && !DECL_WEAK (fn))
719 warning ("the address of `%D', will always be `true'", fn);
720 return cp_truthvalue_conversion (e);
722 return fold (convert_to_integer (type, e));
724 if (code == POINTER_TYPE || code == REFERENCE_TYPE
725 || TYPE_PTRMEMFUNC_P (type))
726 return fold (cp_convert_to_pointer (type, e, 0));
727 if (code == VECTOR_TYPE)
728 return fold (convert_to_vector (type, e));
729 if (code == REAL_TYPE || code == COMPLEX_TYPE)
731 if (IS_AGGR_TYPE (TREE_TYPE (e)))
734 rval = build_type_conversion (type, e, 1);
738 if (flags & LOOKUP_COMPLAIN)
739 error ("`%#T' used where a floating point value was expected",
742 if (code == REAL_TYPE)
743 return fold (convert_to_real (type, e));
744 else if (code == COMPLEX_TYPE)
745 return fold (convert_to_complex (type, e));
748 /* New C++ semantics: since assignment is now based on
749 memberwise copying, if the rhs type is derived from the
750 lhs type, then we may still do a conversion. */
751 if (IS_AGGR_TYPE_CODE (code))
753 tree dtype = TREE_TYPE (e);
754 tree ctor = NULL_TREE;
756 dtype = TYPE_MAIN_VARIANT (dtype);
758 /* Conversion between aggregate types. New C++ semantics allow
759 objects of derived type to be cast to objects of base type.
760 Old semantics only allowed this between pointers.
762 There may be some ambiguity between using a constructor
763 vs. using a type conversion operator when both apply. */
767 if (abstract_virtuals_error (NULL_TREE, type))
768 return error_mark_node;
770 if ((flags & LOOKUP_ONLYCONVERTING)
771 && ! (IS_AGGR_TYPE (dtype) && DERIVED_FROM_P (type, dtype)))
772 /* For copy-initialization, first we create a temp of the proper type
773 with a user-defined conversion sequence, then we direct-initialize
774 the target with the temp (see [dcl.init]). */
775 ctor = build_user_type_conversion (type, ctor, flags);
777 ctor = build_method_call (NULL_TREE,
778 complete_ctor_identifier,
779 build_tree_list (NULL_TREE, ctor),
780 TYPE_BINFO (type), flags);
782 return build_cplus_new (type, ctor);
785 /* If TYPE or TREE_TYPE (E) is not on the permanent_obstack,
786 then it won't be hashed and hence compare as not equal,
788 if (code == ARRAY_TYPE
789 && TREE_TYPE (TREE_TYPE (e)) == TREE_TYPE (type)
790 && index_type_equal (TYPE_DOMAIN (TREE_TYPE (e)), TYPE_DOMAIN (type)))
793 if (flags & LOOKUP_COMPLAIN)
794 error ("conversion from `%T' to non-scalar type `%T' requested",
795 TREE_TYPE (expr), type);
796 if (flags & LOOKUP_SPECULATIVELY)
798 return error_mark_node;
801 /* When an expression is used in a void context, its value is discarded and
802 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
803 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
804 in a void context. The C++ standard does not define what an `access' to an
805 object is, but there is reason to beleive that it is the lvalue to rvalue
806 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
807 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
808 indicates that volatile semantics should be the same between C and C++
809 where ever possible. C leaves it implementation defined as to what
810 constitutes an access to a volatile. So, we interpret `*vp' as a read of
811 the volatile object `vp' points to, unless that is an incomplete type. For
812 volatile references we do not do this interpretation, because that would
813 make it impossible to ignore the reference return value from functions. We
814 issue warnings in the confusing cases.
816 IMPLICIT is tells us the context of an implicit void conversion. */
819 convert_to_void (expr, implicit)
821 const char *implicit;
823 if (expr == error_mark_node
824 || TREE_TYPE (expr) == error_mark_node)
825 return error_mark_node;
826 if (!TREE_TYPE (expr))
828 if (VOID_TYPE_P (TREE_TYPE (expr)))
830 switch (TREE_CODE (expr))
834 /* The two parts of a cond expr might be separate lvalues. */
835 tree op1 = TREE_OPERAND (expr,1);
836 tree op2 = TREE_OPERAND (expr,2);
837 tree new_op1 = convert_to_void (op1, implicit);
838 tree new_op2 = convert_to_void (op2, implicit);
840 expr = build (COND_EXPR, void_type_node,
841 TREE_OPERAND (expr, 0), new_op1, new_op2);
847 /* The second part of a compound expr contains the value. */
848 tree op1 = TREE_OPERAND (expr,1);
849 tree new_op1 = convert_to_void (op1, implicit);
853 tree t = build (COMPOUND_EXPR, TREE_TYPE (new_op1),
854 TREE_OPERAND (expr, 0), new_op1);
855 TREE_SIDE_EFFECTS (t) = TREE_SIDE_EFFECTS (expr);
862 case NON_LVALUE_EXPR:
864 /* These have already decayed to rvalue. */
867 case CALL_EXPR: /* we have a special meaning for volatile void fn() */
872 tree type = TREE_TYPE (expr);
873 int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
875 int is_volatile = TYPE_VOLATILE (type);
876 int is_complete = COMPLETE_TYPE_P (complete_type (type));
878 if (is_volatile && !is_complete)
879 warning ("object of incomplete type `%T' will not be accessed in %s",
880 type, implicit ? implicit : "void context");
881 else if (is_reference && is_volatile)
882 warning ("object of type `%T' will not be accessed in %s",
883 TREE_TYPE (TREE_OPERAND (expr, 0)),
884 implicit ? implicit : "void context");
885 if (is_reference || !is_volatile || !is_complete)
886 expr = TREE_OPERAND (expr, 0);
893 /* External variables might be incomplete. */
894 tree type = TREE_TYPE (expr);
895 int is_complete = COMPLETE_TYPE_P (complete_type (type));
897 if (TYPE_VOLATILE (type) && !is_complete)
898 warning ("object `%E' of incomplete type `%T' will not be accessed in %s",
899 expr, type, implicit ? implicit : "void context");
904 expr = resolve_offset_ref (expr);
912 if (TREE_CODE (probe) == ADDR_EXPR)
913 probe = TREE_OPERAND (expr, 0);
914 if (type_unknown_p (probe))
916 /* [over.over] enumerates the places where we can take the address
917 of an overloaded function, and this is not one of them. */
918 pedwarn ("%s cannot resolve address of overloaded function",
919 implicit ? implicit : "void cast");
921 else if (implicit && probe == expr && is_overloaded_fn (probe))
922 /* Only warn when there is no &. */
923 warning ("%s is a reference, not call, to function `%E'",
927 if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
929 /* FIXME: This is where we should check for expressions with no
930 effects. At the moment we do that in both build_x_component_expr
931 and expand_expr_stmt -- inconsistently too. For the moment
932 leave implicit void conversions unadorned so that expand_expr_stmt
933 has a chance of detecting some of the cases. */
935 expr = build1 (CONVERT_EXPR, void_type_node, expr);
940 /* Create an expression whose value is that of EXPR,
941 converted to type TYPE. The TREE_TYPE of the value
942 is always TYPE. This function implements all reasonable
943 conversions; callers should filter out those that are
944 not permitted by the language being compiled.
946 Most of this routine is from build_reinterpret_cast.
948 The backend cannot call cp_convert (what was convert) because
949 conversions to/from basetypes may involve memory references
950 (vbases) and adding or subtracting small values (multiple
951 inheritance), but it calls convert from the constant folding code
952 on subtrees of already built trees after it has ripped them apart.
954 Also, if we ever support range variables, we'll probably also have to
955 do a little bit more work. */
963 if (type == error_mark_node || expr == error_mark_node)
964 return error_mark_node;
966 intype = TREE_TYPE (expr);
968 if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype))
970 expr = decl_constant_value (expr);
971 return fold (build1 (NOP_EXPR, type, expr));
974 return ocp_convert (type, expr, CONV_OLD_CONVERT,
975 LOOKUP_NORMAL|LOOKUP_NO_CONVERSION);
978 /* Like cp_convert, except permit conversions to take place which
979 are not normally allowed due to access restrictions
980 (such as conversion from sub-type to private super-type). */
983 convert_force (type, expr, convtype)
988 register tree e = expr;
989 register enum tree_code code = TREE_CODE (type);
991 if (code == REFERENCE_TYPE)
992 return fold (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN,
994 else if (TREE_CODE (TREE_TYPE (e)) == REFERENCE_TYPE)
995 e = convert_from_reference (e);
997 if (code == POINTER_TYPE)
998 return fold (convert_to_pointer_force (type, e));
1000 /* From typeck.c convert_for_assignment */
1001 if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR
1002 && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE
1003 && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE)
1004 || integer_zerop (e)
1005 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e)))
1006 && TYPE_PTRMEMFUNC_P (type))
1008 /* compatible pointer to member functions. */
1009 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1);
1012 return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL);
1015 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1016 exists, return the attempted conversion. This may
1017 return ERROR_MARK_NODE if the conversion is not
1018 allowed (references private members, etc).
1019 If no conversion exists, NULL_TREE is returned.
1021 If (FOR_SURE & 1) is non-zero, then we allow this type conversion
1022 to take place immediately. Otherwise, we build a SAVE_EXPR
1023 which can be evaluated if the results are ever needed.
1025 Changes to this functions should be mirrored in user_harshness.
1027 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1028 object parameter, or by the second standard conversion sequence if
1029 that doesn't do it. This will probably wait for an overloading rewrite.
1033 build_type_conversion (xtype, expr, for_sure)
1037 /* C++: check to see if we can convert this aggregate type
1038 into the required type. */
1039 return build_user_type_conversion
1040 (xtype, expr, for_sure ? LOOKUP_NORMAL : 0);
1043 /* Convert the given EXPR to one of a group of types suitable for use in an
1044 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1045 which indicates which types are suitable. If COMPLAIN is 1, complain
1046 about ambiguity; otherwise, the caller will deal with it. */
1049 build_expr_type_conversion (desires, expr, complain)
1054 tree basetype = TREE_TYPE (expr);
1055 tree conv = NULL_TREE;
1056 tree winner = NULL_TREE;
1058 if (expr == null_node
1059 && (desires & WANT_INT)
1060 && !(desires & WANT_NULL))
1061 warning ("converting NULL to non-pointer type");
1063 if (TREE_CODE (expr) == OFFSET_REF)
1064 expr = resolve_offset_ref (expr);
1065 expr = convert_from_reference (expr);
1066 basetype = TREE_TYPE (expr);
1068 if (basetype == error_mark_node)
1069 return error_mark_node;
1071 if (! IS_AGGR_TYPE (basetype))
1072 switch (TREE_CODE (basetype))
1075 if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
1077 /* else fall through... */
1080 return (desires & WANT_INT) ? expr : NULL_TREE;
1082 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1084 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1086 return (desires & WANT_POINTER) ? expr : NULL_TREE;
1090 return (desires & WANT_POINTER) ? default_conversion (expr)
1096 /* The code for conversions from class type is currently only used for
1097 delete expressions. Other expressions are handled by build_new_op. */
1099 if (! TYPE_HAS_CONVERSION (basetype))
1102 for (conv = lookup_conversions (basetype); conv; conv = TREE_CHAIN (conv))
1106 tree cand = TREE_VALUE (conv);
1108 if (winner && winner == cand)
1111 candidate = TREE_TYPE (TREE_TYPE (cand));
1112 if (TREE_CODE (candidate) == REFERENCE_TYPE)
1113 candidate = TREE_TYPE (candidate);
1115 switch (TREE_CODE (candidate))
1119 win = (desires & WANT_INT); break;
1121 win = (desires & WANT_ENUM); break;
1123 win = (desires & WANT_FLOAT); break;
1125 win = (desires & WANT_POINTER); break;
1137 error ("ambiguous default type conversion from `%T'",
1139 error (" candidate conversions include `%D' and `%D'",
1142 return error_mark_node;
1151 tree type = TREE_TYPE (TREE_TYPE (winner));
1152 if (TREE_CODE (type) == REFERENCE_TYPE)
1153 type = TREE_TYPE (type);
1154 return build_user_type_conversion (type, expr, LOOKUP_NORMAL);
1160 /* Implements integral promotion (4.1) and float->double promotion. */
1163 type_promotes_to (type)
1168 if (type == error_mark_node)
1169 return error_mark_node;
1171 type_quals = cp_type_quals (type);
1172 type = TYPE_MAIN_VARIANT (type);
1174 /* bool always promotes to int (not unsigned), even if it's the same
1176 if (type == boolean_type_node)
1177 type = integer_type_node;
1179 /* Normally convert enums to int, but convert wide enums to something
1181 else if (TREE_CODE (type) == ENUMERAL_TYPE
1182 || type == wchar_type_node)
1184 int precision = MAX (TYPE_PRECISION (type),
1185 TYPE_PRECISION (integer_type_node));
1186 tree totype = type_for_size (precision, 0);
1187 if (TREE_UNSIGNED (type)
1188 && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype))
1189 type = type_for_size (precision, 1);
1193 else if (c_promoting_integer_type_p (type))
1195 /* Retain unsignedness if really not getting bigger. */
1196 if (TREE_UNSIGNED (type)
1197 && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1198 type = unsigned_type_node;
1200 type = integer_type_node;
1202 else if (type == float_type_node)
1203 type = double_type_node;
1205 return cp_build_qualified_type (type, type_quals);
1208 /* The routines below this point are carefully written to conform to
1209 the standard. They use the same terminology, and follow the rules
1210 closely. Although they are used only in pt.c at the moment, they
1211 should presumably be used everywhere in the future. */
1213 /* Attempt to perform qualification conversions on EXPR to convert it
1214 to TYPE. Return the resulting expression, or error_mark_node if
1215 the conversion was impossible. */
1218 perform_qualification_conversions (type, expr)
1222 if (TREE_CODE (type) == POINTER_TYPE
1223 && TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE
1224 && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (TREE_TYPE (expr))))
1225 return build1 (NOP_EXPR, type, expr);
1227 return error_mark_node;