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, tf_error | tf_warning);
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 ? tf_error | tf_warning : tf_none);
482 if (expr == error_mark_node)
483 return error_mark_node;
485 intype = TREE_TYPE (expr);
488 my_friendly_assert (TREE_CODE (intype) != REFERENCE_TYPE, 364);
490 intype = TYPE_MAIN_VARIANT (intype);
492 i = comp_target_types (type, intype, 0);
494 if (i <= 0 && (convtype & CONV_IMPLICIT) && IS_AGGR_TYPE (intype)
495 && ! (flags & LOOKUP_NO_CONVERSION))
497 /* Look for a user-defined conversion to lvalue that we can use. */
500 = build_type_conversion (reftype, expr, 1);
502 if (rval_as_conversion && rval_as_conversion != error_mark_node
503 && real_lvalue_p (rval_as_conversion))
505 expr = rval_as_conversion;
506 rval_as_conversion = NULL_TREE;
512 if (((convtype & CONV_STATIC) && i == -1)
513 || ((convtype & CONV_IMPLICIT) && i == 1))
515 if (flags & LOOKUP_COMPLAIN)
517 tree ttl = TREE_TYPE (reftype);
518 tree ttr = lvalue_type (expr);
520 if (! real_lvalue_p (expr))
521 warn_ref_binding (reftype, intype, decl);
523 if (! (convtype & CONV_CONST)
524 && !at_least_as_qualified_p (ttl, ttr))
525 pedwarn ("conversion from `%T' to `%T' discards qualifiers",
529 return build_up_reference (reftype, expr, flags, decl);
531 else if ((convtype & CONV_REINTERPRET) && lvalue_p (expr))
533 /* When casting an lvalue to a reference type, just convert into
534 a pointer to the new type and deference it. This is allowed
535 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
536 should be done directly (jason). (int &)ri ---> *(int*)&ri */
538 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
540 if (TREE_CODE (intype) == POINTER_TYPE
541 && (comptypes (TREE_TYPE (intype), type,
542 COMPARE_BASE | COMPARE_RELAXED )))
543 warning ("casting `%T' to `%T' does not dereference pointer",
546 rval = build_unary_op (ADDR_EXPR, expr, 0);
547 if (rval != error_mark_node)
548 rval = convert_force (build_pointer_type (TREE_TYPE (reftype)),
550 if (rval != error_mark_node)
551 rval = build1 (NOP_EXPR, reftype, rval);
555 rval = convert_for_initialization (NULL_TREE, type, expr, flags,
557 if (rval == NULL_TREE || rval == error_mark_node)
559 warn_ref_binding (reftype, intype, decl);
560 rval = build_up_reference (reftype, rval, flags, decl);
565 /* If we found a way to convert earlier, then use it. */
569 my_friendly_assert (TREE_CODE (intype) != OFFSET_TYPE, 189);
571 if (flags & LOOKUP_COMPLAIN)
572 error ("cannot convert type `%T' to type `%T'", intype, reftype);
574 if (flags & LOOKUP_SPECULATIVELY)
577 return error_mark_node;
580 /* We are using a reference VAL for its value. Bash that reference all the
581 way down to its lowest form. */
584 convert_from_reference (val)
587 tree type = TREE_TYPE (val);
589 if (TREE_CODE (type) == OFFSET_TYPE)
590 type = TREE_TYPE (type);
591 if (TREE_CODE (type) == REFERENCE_TYPE)
592 return build_indirect_ref (val, NULL);
596 /* Implicitly convert the lvalue EXPR to another lvalue of type TOTYPE,
597 preserving cv-qualification. */
600 convert_lvalue (totype, expr)
603 totype = cp_build_qualified_type (totype, TYPE_QUALS (TREE_TYPE (expr)));
604 totype = build_reference_type (totype);
605 expr = convert_to_reference (totype, expr, CONV_IMPLICIT, LOOKUP_NORMAL,
607 return convert_from_reference (expr);
610 /* C++ conversions, preference to static cast conversions. */
613 cp_convert (type, expr)
616 return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL);
621 FLAGS indicates how we should behave. */
624 ocp_convert (type, expr, convtype, flags)
628 register tree e = expr;
629 register enum tree_code code = TREE_CODE (type);
631 if (e == error_mark_node
632 || TREE_TYPE (e) == error_mark_node)
633 return error_mark_node;
635 complete_type (type);
636 complete_type (TREE_TYPE (expr));
638 e = decl_constant_value (e);
640 if (IS_AGGR_TYPE (type) && (convtype & CONV_FORCE_TEMP)
641 /* Some internal structures (vtable_entry_type, sigtbl_ptr_type)
642 don't go through finish_struct, so they don't have the synthesized
643 constructors. So don't force a temporary. */
644 && TYPE_HAS_CONSTRUCTOR (type))
645 /* We need a new temporary; don't take this shortcut. */;
646 else if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (e)))
648 if (same_type_p (type, TREE_TYPE (e)))
649 /* The call to fold will not always remove the NOP_EXPR as
650 might be expected, since if one of the types is a typedef;
651 the comparsion in fold is just equality of pointers, not a
652 call to comptypes. We don't call fold in this case because
653 that can result in infinite recursion; fold will call
654 convert, which will call ocp_convert, etc. */
656 /* For complex data types, we need to perform componentwise
658 else if (TREE_CODE (type) == COMPLEX_TYPE)
659 return fold (convert_to_complex (type, e));
661 return fold (build1 (NOP_EXPR, type, e));
664 if (code == VOID_TYPE && (convtype & CONV_STATIC))
666 e = convert_to_void (e, /*implicit=*/NULL);
670 /* Just convert to the type of the member. */
671 if (code == OFFSET_TYPE)
673 type = TREE_TYPE (type);
674 code = TREE_CODE (type);
677 if (TREE_CODE (e) == OFFSET_REF)
678 e = resolve_offset_ref (e);
680 if (INTEGRAL_CODE_P (code))
682 tree intype = TREE_TYPE (e);
683 /* enum = enum, enum = int, enum = float, (enum)pointer are all
685 if (TREE_CODE (type) == ENUMERAL_TYPE
686 && ((ARITHMETIC_TYPE_P (intype) && ! (convtype & CONV_STATIC))
687 || (TREE_CODE (intype) == POINTER_TYPE)))
689 pedwarn ("conversion from `%#T' to `%#T'", intype, type);
691 if (flag_pedantic_errors)
692 return error_mark_node;
694 if (IS_AGGR_TYPE (intype))
697 rval = build_type_conversion (type, e, 1);
700 if (flags & LOOKUP_COMPLAIN)
701 error ("`%#T' used where a `%T' was expected", intype, type);
702 if (flags & LOOKUP_SPECULATIVELY)
704 return error_mark_node;
706 if (code == BOOLEAN_TYPE)
710 /* Common Ada/Pascal programmer's mistake. We always warn
711 about this since it is so bad. */
712 if (TREE_CODE (expr) == FUNCTION_DECL)
714 else if (TREE_CODE (expr) == ADDR_EXPR
715 && TREE_CODE (TREE_OPERAND (expr, 0)) == FUNCTION_DECL)
716 fn = TREE_OPERAND (expr, 0);
717 if (fn && !DECL_WEAK (fn))
718 warning ("the address of `%D', will always be `true'", fn);
719 return cp_truthvalue_conversion (e);
721 return fold (convert_to_integer (type, e));
723 if (code == POINTER_TYPE || code == REFERENCE_TYPE
724 || TYPE_PTRMEMFUNC_P (type))
725 return fold (cp_convert_to_pointer (type, e, 0));
726 if (code == VECTOR_TYPE)
727 return fold (convert_to_vector (type, e));
728 if (code == REAL_TYPE || code == COMPLEX_TYPE)
730 if (IS_AGGR_TYPE (TREE_TYPE (e)))
733 rval = build_type_conversion (type, e, 1);
737 if (flags & LOOKUP_COMPLAIN)
738 error ("`%#T' used where a floating point value was expected",
741 if (code == REAL_TYPE)
742 return fold (convert_to_real (type, e));
743 else if (code == COMPLEX_TYPE)
744 return fold (convert_to_complex (type, e));
747 /* New C++ semantics: since assignment is now based on
748 memberwise copying, if the rhs type is derived from the
749 lhs type, then we may still do a conversion. */
750 if (IS_AGGR_TYPE_CODE (code))
752 tree dtype = TREE_TYPE (e);
753 tree ctor = NULL_TREE;
755 dtype = TYPE_MAIN_VARIANT (dtype);
757 /* Conversion between aggregate types. New C++ semantics allow
758 objects of derived type to be cast to objects of base type.
759 Old semantics only allowed this between pointers.
761 There may be some ambiguity between using a constructor
762 vs. using a type conversion operator when both apply. */
766 if (abstract_virtuals_error (NULL_TREE, type))
767 return error_mark_node;
769 if ((flags & LOOKUP_ONLYCONVERTING)
770 && ! (IS_AGGR_TYPE (dtype) && DERIVED_FROM_P (type, dtype)))
771 /* For copy-initialization, first we create a temp of the proper type
772 with a user-defined conversion sequence, then we direct-initialize
773 the target with the temp (see [dcl.init]). */
774 ctor = build_user_type_conversion (type, ctor, flags);
776 ctor = build_method_call (NULL_TREE,
777 complete_ctor_identifier,
778 build_tree_list (NULL_TREE, ctor),
779 TYPE_BINFO (type), flags);
781 return build_cplus_new (type, ctor);
784 /* If TYPE or TREE_TYPE (E) is not on the permanent_obstack,
785 then it won't be hashed and hence compare as not equal,
787 if (code == ARRAY_TYPE
788 && TREE_TYPE (TREE_TYPE (e)) == TREE_TYPE (type)
789 && index_type_equal (TYPE_DOMAIN (TREE_TYPE (e)), TYPE_DOMAIN (type)))
792 if (flags & LOOKUP_COMPLAIN)
793 error ("conversion from `%T' to non-scalar type `%T' requested",
794 TREE_TYPE (expr), type);
795 if (flags & LOOKUP_SPECULATIVELY)
797 return error_mark_node;
800 /* When an expression is used in a void context, its value is discarded and
801 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
802 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
803 in a void context. The C++ standard does not define what an `access' to an
804 object is, but there is reason to beleive that it is the lvalue to rvalue
805 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
806 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
807 indicates that volatile semantics should be the same between C and C++
808 where ever possible. C leaves it implementation defined as to what
809 constitutes an access to a volatile. So, we interpret `*vp' as a read of
810 the volatile object `vp' points to, unless that is an incomplete type. For
811 volatile references we do not do this interpretation, because that would
812 make it impossible to ignore the reference return value from functions. We
813 issue warnings in the confusing cases.
815 IMPLICIT is tells us the context of an implicit void conversion. */
818 convert_to_void (expr, implicit)
820 const char *implicit;
822 if (expr == error_mark_node
823 || TREE_TYPE (expr) == error_mark_node)
824 return error_mark_node;
825 if (!TREE_TYPE (expr))
827 if (VOID_TYPE_P (TREE_TYPE (expr)))
829 switch (TREE_CODE (expr))
833 /* The two parts of a cond expr might be separate lvalues. */
834 tree op1 = TREE_OPERAND (expr,1);
835 tree op2 = TREE_OPERAND (expr,2);
836 tree new_op1 = convert_to_void (op1, implicit);
837 tree new_op2 = convert_to_void (op2, implicit);
839 expr = build (COND_EXPR, void_type_node,
840 TREE_OPERAND (expr, 0), new_op1, new_op2);
846 /* The second part of a compound expr contains the value. */
847 tree op1 = TREE_OPERAND (expr,1);
848 tree new_op1 = convert_to_void (op1, implicit);
852 tree t = build (COMPOUND_EXPR, TREE_TYPE (new_op1),
853 TREE_OPERAND (expr, 0), new_op1);
854 TREE_SIDE_EFFECTS (t) = TREE_SIDE_EFFECTS (expr);
861 case NON_LVALUE_EXPR:
863 /* These have already decayed to rvalue. */
866 case CALL_EXPR: /* we have a special meaning for volatile void fn() */
871 tree type = TREE_TYPE (expr);
872 int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
874 int is_volatile = TYPE_VOLATILE (type);
875 int is_complete = COMPLETE_TYPE_P (complete_type (type));
877 if (is_volatile && !is_complete)
878 warning ("object of incomplete type `%T' will not be accessed in %s",
879 type, implicit ? implicit : "void context");
880 else if (is_reference && is_volatile)
881 warning ("object of type `%T' will not be accessed in %s",
882 TREE_TYPE (TREE_OPERAND (expr, 0)),
883 implicit ? implicit : "void context");
884 if (is_reference || !is_volatile || !is_complete)
885 expr = TREE_OPERAND (expr, 0);
892 /* External variables might be incomplete. */
893 tree type = TREE_TYPE (expr);
894 int is_complete = COMPLETE_TYPE_P (complete_type (type));
896 if (TYPE_VOLATILE (type) && !is_complete)
897 warning ("object `%E' of incomplete type `%T' will not be accessed in %s",
898 expr, type, implicit ? implicit : "void context");
903 expr = resolve_offset_ref (expr);
911 if (TREE_CODE (probe) == ADDR_EXPR)
912 probe = TREE_OPERAND (expr, 0);
913 if (type_unknown_p (probe))
915 /* [over.over] enumerates the places where we can take the address
916 of an overloaded function, and this is not one of them. */
917 pedwarn ("%s cannot resolve address of overloaded function",
918 implicit ? implicit : "void cast");
920 else if (implicit && probe == expr && is_overloaded_fn (probe))
921 /* Only warn when there is no &. */
922 warning ("%s is a reference, not call, to function `%E'",
926 if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
928 /* FIXME: This is where we should check for expressions with no
929 effects. At the moment we do that in both build_x_component_expr
930 and expand_expr_stmt -- inconsistently too. For the moment
931 leave implicit void conversions unadorned so that expand_expr_stmt
932 has a chance of detecting some of the cases. */
934 expr = build1 (CONVERT_EXPR, void_type_node, expr);
939 /* Create an expression whose value is that of EXPR,
940 converted to type TYPE. The TREE_TYPE of the value
941 is always TYPE. This function implements all reasonable
942 conversions; callers should filter out those that are
943 not permitted by the language being compiled.
945 Most of this routine is from build_reinterpret_cast.
947 The backend cannot call cp_convert (what was convert) because
948 conversions to/from basetypes may involve memory references
949 (vbases) and adding or subtracting small values (multiple
950 inheritance), but it calls convert from the constant folding code
951 on subtrees of already built trees after it has ripped them apart.
953 Also, if we ever support range variables, we'll probably also have to
954 do a little bit more work. */
962 if (type == error_mark_node || expr == error_mark_node)
963 return error_mark_node;
965 intype = TREE_TYPE (expr);
967 if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype))
969 expr = decl_constant_value (expr);
970 return fold (build1 (NOP_EXPR, type, expr));
973 return ocp_convert (type, expr, CONV_OLD_CONVERT,
974 LOOKUP_NORMAL|LOOKUP_NO_CONVERSION);
977 /* Like cp_convert, except permit conversions to take place which
978 are not normally allowed due to access restrictions
979 (such as conversion from sub-type to private super-type). */
982 convert_force (type, expr, convtype)
987 register tree e = expr;
988 register enum tree_code code = TREE_CODE (type);
990 if (code == REFERENCE_TYPE)
991 return fold (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN,
993 else if (TREE_CODE (TREE_TYPE (e)) == REFERENCE_TYPE)
994 e = convert_from_reference (e);
996 if (code == POINTER_TYPE)
997 return fold (convert_to_pointer_force (type, e));
999 /* From typeck.c convert_for_assignment */
1000 if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR
1001 && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE
1002 && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE)
1003 || integer_zerop (e)
1004 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e)))
1005 && TYPE_PTRMEMFUNC_P (type))
1007 /* compatible pointer to member functions. */
1008 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1);
1011 return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL);
1014 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1015 exists, return the attempted conversion. This may
1016 return ERROR_MARK_NODE if the conversion is not
1017 allowed (references private members, etc).
1018 If no conversion exists, NULL_TREE is returned.
1020 If (FOR_SURE & 1) is non-zero, then we allow this type conversion
1021 to take place immediately. Otherwise, we build a SAVE_EXPR
1022 which can be evaluated if the results are ever needed.
1024 Changes to this functions should be mirrored in user_harshness.
1026 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1027 object parameter, or by the second standard conversion sequence if
1028 that doesn't do it. This will probably wait for an overloading rewrite.
1032 build_type_conversion (xtype, expr, for_sure)
1036 /* C++: check to see if we can convert this aggregate type
1037 into the required type. */
1038 return build_user_type_conversion
1039 (xtype, expr, for_sure ? LOOKUP_NORMAL : 0);
1042 /* Convert the given EXPR to one of a group of types suitable for use in an
1043 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1044 which indicates which types are suitable. If COMPLAIN is 1, complain
1045 about ambiguity; otherwise, the caller will deal with it. */
1048 build_expr_type_conversion (desires, expr, complain)
1053 tree basetype = TREE_TYPE (expr);
1054 tree conv = NULL_TREE;
1055 tree winner = NULL_TREE;
1057 if (expr == null_node
1058 && (desires & WANT_INT)
1059 && !(desires & WANT_NULL))
1060 warning ("converting NULL to non-pointer type");
1062 if (TREE_CODE (expr) == OFFSET_REF)
1063 expr = resolve_offset_ref (expr);
1064 expr = convert_from_reference (expr);
1065 basetype = TREE_TYPE (expr);
1067 if (basetype == error_mark_node)
1068 return error_mark_node;
1070 if (! IS_AGGR_TYPE (basetype))
1071 switch (TREE_CODE (basetype))
1074 if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
1076 /* else fall through... */
1079 return (desires & WANT_INT) ? expr : NULL_TREE;
1081 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1083 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1085 return (desires & WANT_POINTER) ? expr : NULL_TREE;
1089 return (desires & WANT_POINTER) ? default_conversion (expr)
1095 /* The code for conversions from class type is currently only used for
1096 delete expressions. Other expressions are handled by build_new_op. */
1098 if (! TYPE_HAS_CONVERSION (basetype))
1101 for (conv = lookup_conversions (basetype); conv; conv = TREE_CHAIN (conv))
1105 tree cand = TREE_VALUE (conv);
1107 if (winner && winner == cand)
1110 candidate = TREE_TYPE (TREE_TYPE (cand));
1111 if (TREE_CODE (candidate) == REFERENCE_TYPE)
1112 candidate = TREE_TYPE (candidate);
1114 switch (TREE_CODE (candidate))
1118 win = (desires & WANT_INT); break;
1120 win = (desires & WANT_ENUM); break;
1122 win = (desires & WANT_FLOAT); break;
1124 win = (desires & WANT_POINTER); break;
1136 error ("ambiguous default type conversion from `%T'",
1138 error (" candidate conversions include `%D' and `%D'",
1141 return error_mark_node;
1150 tree type = TREE_TYPE (TREE_TYPE (winner));
1151 if (TREE_CODE (type) == REFERENCE_TYPE)
1152 type = TREE_TYPE (type);
1153 return build_user_type_conversion (type, expr, LOOKUP_NORMAL);
1159 /* Implements integral promotion (4.1) and float->double promotion. */
1162 type_promotes_to (type)
1167 if (type == error_mark_node)
1168 return error_mark_node;
1170 type_quals = cp_type_quals (type);
1171 type = TYPE_MAIN_VARIANT (type);
1173 /* bool always promotes to int (not unsigned), even if it's the same
1175 if (type == boolean_type_node)
1176 type = integer_type_node;
1178 /* Normally convert enums to int, but convert wide enums to something
1180 else if (TREE_CODE (type) == ENUMERAL_TYPE
1181 || type == wchar_type_node)
1183 int precision = MAX (TYPE_PRECISION (type),
1184 TYPE_PRECISION (integer_type_node));
1185 tree totype = type_for_size (precision, 0);
1186 if (TREE_UNSIGNED (type)
1187 && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype))
1188 type = type_for_size (precision, 1);
1192 else if (c_promoting_integer_type_p (type))
1194 /* Retain unsignedness if really not getting bigger. */
1195 if (TREE_UNSIGNED (type)
1196 && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1197 type = unsigned_type_node;
1199 type = integer_type_node;
1201 else if (type == float_type_node)
1202 type = double_type_node;
1204 return cp_build_qualified_type (type, type_quals);
1207 /* The routines below this point are carefully written to conform to
1208 the standard. They use the same terminology, and follow the rules
1209 closely. Although they are used only in pt.c at the moment, they
1210 should presumably be used everywhere in the future. */
1212 /* Attempt to perform qualification conversions on EXPR to convert it
1213 to TYPE. Return the resulting expression, or error_mark_node if
1214 the conversion was impossible. */
1217 perform_qualification_conversions (type, expr)
1221 if (TREE_CODE (type) == POINTER_TYPE
1222 && TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE
1223 && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (TREE_TYPE (expr))))
1224 return build1 (NOP_EXPR, type, expr);
1226 return error_mark_node;