revert: re PR c++/35049 (g++.dg/conversion/simd3.C:12: error: invalid operands to...
[official-gcc.git] / gcc / cp / cvt.c
blob2911fea06432ef249ff6b84515b9efcdc2757091
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, 2003, 2004, 2005, 2006, 2007
4 Free Software Foundation, Inc.
5 Hacked by Michael Tiemann (tiemann@cygnus.com)
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3, or (at your option)
12 any later version.
14 GCC is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING3. If not see
21 <http://www.gnu.org/licenses/>. */
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. */
29 #include "config.h"
30 #include "system.h"
31 #include "coretypes.h"
32 #include "tm.h"
33 #include "tree.h"
34 #include "flags.h"
35 #include "cp-tree.h"
36 #include "convert.h"
37 #include "toplev.h"
38 #include "decl.h"
39 #include "target.h"
41 static tree cp_convert_to_pointer (tree, tree);
42 static tree convert_to_pointer_force (tree, tree);
43 static tree build_type_conversion (tree, tree);
44 static tree build_up_reference (tree, tree, int, tree);
45 static void warn_ref_binding (tree, tree, tree);
47 /* Change of width--truncation and extension of integers or reals--
48 is represented with NOP_EXPR. Proper functioning of many things
49 assumes that no other conversions can be NOP_EXPRs.
51 Conversion between integer and pointer is represented with CONVERT_EXPR.
52 Converting integer to real uses FLOAT_EXPR
53 and real to integer uses FIX_TRUNC_EXPR.
55 Here is a list of all the functions that assume that widening and
56 narrowing is always done with a NOP_EXPR:
57 In convert.c, convert_to_integer.
58 In c-typeck.c, build_binary_op_nodefault (boolean ops),
59 and c_common_truthvalue_conversion.
60 In expr.c: expand_expr, for operands of a MULT_EXPR.
61 In fold-const.c: fold.
62 In tree.c: get_narrower and get_unwidened.
64 C++: in multiple-inheritance, converting between pointers may involve
65 adjusting them by a delta stored within the class definition. */
67 /* Subroutines of `convert'. */
69 /* if converting pointer to pointer
70 if dealing with classes, check for derived->base or vice versa
71 else if dealing with method pointers, delegate
72 else convert blindly
73 else if converting class, pass off to build_type_conversion
74 else try C-style pointer conversion. */
76 static tree
77 cp_convert_to_pointer (tree type, tree expr)
79 tree intype = TREE_TYPE (expr);
80 enum tree_code form;
81 tree rval;
82 if (intype == error_mark_node)
83 return error_mark_node;
85 if (IS_AGGR_TYPE (intype))
87 intype = complete_type (intype);
88 if (!COMPLETE_TYPE_P (intype))
90 error ("can't convert from incomplete type %qT to %qT",
91 intype, type);
92 return error_mark_node;
95 rval = build_type_conversion (type, expr);
96 if (rval)
98 if (rval == error_mark_node)
99 error ("conversion of %qE from %qT to %qT is ambiguous",
100 expr, intype, type);
101 return rval;
105 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
106 if (TREE_CODE (type) == POINTER_TYPE
107 && (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
108 || VOID_TYPE_P (TREE_TYPE (type))))
110 if (TYPE_PTRMEMFUNC_P (intype)
111 || TREE_CODE (intype) == METHOD_TYPE)
112 return convert_member_func_to_ptr (type, expr);
113 if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
114 return build_nop (type, expr);
115 intype = TREE_TYPE (expr);
118 if (expr == error_mark_node)
119 return error_mark_node;
121 form = TREE_CODE (intype);
123 if (POINTER_TYPE_P (intype))
125 intype = TYPE_MAIN_VARIANT (intype);
127 if (TYPE_MAIN_VARIANT (type) != intype
128 && TREE_CODE (type) == POINTER_TYPE
129 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
130 && IS_AGGR_TYPE (TREE_TYPE (type))
131 && IS_AGGR_TYPE (TREE_TYPE (intype))
132 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
134 enum tree_code code = PLUS_EXPR;
135 tree binfo;
136 tree intype_class;
137 tree type_class;
138 bool same_p;
140 intype_class = TREE_TYPE (intype);
141 type_class = TREE_TYPE (type);
143 same_p = same_type_p (TYPE_MAIN_VARIANT (intype_class),
144 TYPE_MAIN_VARIANT (type_class));
145 binfo = NULL_TREE;
146 /* Try derived to base conversion. */
147 if (!same_p)
148 binfo = lookup_base (intype_class, type_class, ba_check, NULL);
149 if (!same_p && !binfo)
151 /* Try base to derived conversion. */
152 binfo = lookup_base (type_class, intype_class, ba_check, NULL);
153 code = MINUS_EXPR;
155 if (binfo == error_mark_node)
156 return error_mark_node;
157 if (binfo || same_p)
159 if (binfo)
160 expr = build_base_path (code, expr, binfo, 0);
161 /* Add any qualifier conversions. */
162 return build_nop (type, expr);
166 if (TYPE_PTRMEMFUNC_P (type))
168 error ("cannot convert %qE from type %qT to type %qT",
169 expr, intype, type);
170 return error_mark_node;
173 return build_nop (type, expr);
175 else if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
176 || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
177 return convert_ptrmem (type, expr, /*allow_inverse_p=*/false,
178 /*c_cast_p=*/false);
179 else if (TYPE_PTRMEMFUNC_P (intype))
181 if (!warn_pmf2ptr)
183 if (TREE_CODE (expr) == PTRMEM_CST)
184 return cp_convert_to_pointer (type,
185 PTRMEM_CST_MEMBER (expr));
186 else if (TREE_CODE (expr) == OFFSET_REF)
188 tree object = TREE_OPERAND (expr, 0);
189 return get_member_function_from_ptrfunc (&object,
190 TREE_OPERAND (expr, 1));
193 error ("cannot convert %qE from type %qT to type %qT",
194 expr, intype, type);
195 return error_mark_node;
198 if (integer_zerop (expr))
200 if (TYPE_PTRMEMFUNC_P (type))
201 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0,
202 /*c_cast_p=*/false);
204 if (TYPE_PTRMEM_P (type))
206 /* A NULL pointer-to-member is represented by -1, not by
207 zero. */
208 expr = build_int_cst_type (type, -1);
210 else
211 expr = build_int_cst (type, 0);
213 return expr;
215 else if (TYPE_PTR_TO_MEMBER_P (type) && INTEGRAL_CODE_P (form))
217 error ("invalid conversion from %qT to %qT", intype, type);
218 return error_mark_node;
221 if (INTEGRAL_CODE_P (form))
223 if (TYPE_PRECISION (intype) == POINTER_SIZE)
224 return build1 (CONVERT_EXPR, type, expr);
225 expr = cp_convert (c_common_type_for_size (POINTER_SIZE, 0), expr);
226 /* Modes may be different but sizes should be the same. There
227 is supposed to be some integral type that is the same width
228 as a pointer. */
229 gcc_assert (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr)))
230 == GET_MODE_SIZE (TYPE_MODE (type)));
232 return convert_to_pointer (type, expr);
235 if (type_unknown_p (expr))
236 return instantiate_type (type, expr, tf_warning_or_error);
238 error ("cannot convert %qE from type %qT to type %qT",
239 expr, intype, type);
240 return error_mark_node;
243 /* Like convert, except permit conversions to take place which
244 are not normally allowed due to access restrictions
245 (such as conversion from sub-type to private super-type). */
247 static tree
248 convert_to_pointer_force (tree type, tree expr)
250 tree intype = TREE_TYPE (expr);
251 enum tree_code form = TREE_CODE (intype);
253 if (form == POINTER_TYPE)
255 intype = TYPE_MAIN_VARIANT (intype);
257 if (TYPE_MAIN_VARIANT (type) != intype
258 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
259 && IS_AGGR_TYPE (TREE_TYPE (type))
260 && IS_AGGR_TYPE (TREE_TYPE (intype))
261 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
263 enum tree_code code = PLUS_EXPR;
264 tree binfo;
266 binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
267 ba_unique, NULL);
268 if (!binfo)
270 binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
271 ba_unique, NULL);
272 code = MINUS_EXPR;
274 if (binfo == error_mark_node)
275 return error_mark_node;
276 if (binfo)
278 expr = build_base_path (code, expr, binfo, 0);
279 if (expr == error_mark_node)
280 return error_mark_node;
281 /* Add any qualifier conversions. */
282 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)),
283 TREE_TYPE (type)))
284 expr = build_nop (type, expr);
285 return expr;
290 return cp_convert_to_pointer (type, expr);
293 /* We are passing something to a function which requires a reference.
294 The type we are interested in is in TYPE. The initial
295 value we have to begin with is in ARG.
297 FLAGS controls how we manage access checking.
298 DIRECT_BIND in FLAGS controls how any temporaries are generated.
299 If DIRECT_BIND is set, DECL is the reference we're binding to. */
301 static tree
302 build_up_reference (tree type, tree arg, int flags, tree decl)
304 tree rval;
305 tree argtype = TREE_TYPE (arg);
306 tree target_type = TREE_TYPE (type);
308 gcc_assert (TREE_CODE (type) == REFERENCE_TYPE);
310 if ((flags & DIRECT_BIND) && ! real_lvalue_p (arg))
312 /* Create a new temporary variable. We can't just use a TARGET_EXPR
313 here because it needs to live as long as DECL. */
314 tree targ = arg;
316 arg = make_temporary_var_for_ref_to_temp (decl, TREE_TYPE (arg));
318 /* Process the initializer for the declaration. */
319 DECL_INITIAL (arg) = targ;
320 cp_finish_decl (arg, targ, /*init_const_expr_p=*/false, NULL_TREE,
321 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
323 else if (!(flags & DIRECT_BIND) && ! lvalue_p (arg))
324 return get_target_expr (arg);
326 /* If we had a way to wrap this up, and say, if we ever needed its
327 address, transform all occurrences of the register, into a memory
328 reference we could win better. */
329 rval = build_unary_op (ADDR_EXPR, arg, 1);
330 if (rval == error_mark_node)
331 return error_mark_node;
333 if ((flags & LOOKUP_PROTECT)
334 && TYPE_MAIN_VARIANT (argtype) != TYPE_MAIN_VARIANT (target_type)
335 && IS_AGGR_TYPE (argtype)
336 && IS_AGGR_TYPE (target_type))
338 /* We go through lookup_base for the access control. */
339 tree binfo = lookup_base (argtype, target_type, ba_check, NULL);
340 if (binfo == error_mark_node)
341 return error_mark_node;
342 if (binfo == NULL_TREE)
343 return error_not_base_type (target_type, argtype);
344 rval = build_base_path (PLUS_EXPR, rval, binfo, 1);
346 else
347 rval
348 = convert_to_pointer_force (build_pointer_type (target_type), rval);
349 return build_nop (type, rval);
352 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
353 INTYPE is the original rvalue type and DECL is an optional _DECL node
354 for diagnostics.
356 [dcl.init.ref] says that if an rvalue is used to
357 initialize a reference, then the reference must be to a
358 non-volatile const type. */
360 static void
361 warn_ref_binding (tree reftype, tree intype, tree decl)
363 tree ttl = TREE_TYPE (reftype);
365 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl))
367 const char *msg;
369 if (CP_TYPE_VOLATILE_P (ttl) && decl)
370 msg = "initialization of volatile reference type %q#T from"
371 " rvalue of type %qT";
372 else if (CP_TYPE_VOLATILE_P (ttl))
373 msg = "conversion to volatile reference type %q#T "
374 " from rvalue of type %qT";
375 else if (decl)
376 msg = "initialization of non-const reference type %q#T from"
377 " rvalue of type %qT";
378 else
379 msg = "conversion to non-const reference type %q#T from"
380 " rvalue of type %qT";
382 permerror (msg, reftype, intype);
386 /* For C++: Only need to do one-level references, but cannot
387 get tripped up on signed/unsigned differences.
389 DECL is either NULL_TREE or the _DECL node for a reference that is being
390 initialized. It can be error_mark_node if we don't know the _DECL but
391 we know it's an initialization. */
393 tree
394 convert_to_reference (tree reftype, tree expr, int convtype,
395 int flags, tree decl)
397 tree type = TYPE_MAIN_VARIANT (TREE_TYPE (reftype));
398 tree intype;
399 tree rval = NULL_TREE;
400 tree rval_as_conversion = NULL_TREE;
401 bool can_convert_intype_to_type;
403 if (TREE_CODE (type) == FUNCTION_TYPE
404 && TREE_TYPE (expr) == unknown_type_node)
405 expr = instantiate_type (type, expr,
406 (flags & LOOKUP_COMPLAIN)
407 ? tf_warning_or_error : tf_none);
409 if (expr == error_mark_node)
410 return error_mark_node;
412 intype = TREE_TYPE (expr);
414 gcc_assert (TREE_CODE (intype) != REFERENCE_TYPE);
415 gcc_assert (TREE_CODE (reftype) == REFERENCE_TYPE);
417 intype = TYPE_MAIN_VARIANT (intype);
419 can_convert_intype_to_type = can_convert (type, intype);
420 if (!can_convert_intype_to_type
421 && (convtype & CONV_IMPLICIT) && IS_AGGR_TYPE (intype)
422 && ! (flags & LOOKUP_NO_CONVERSION))
424 /* Look for a user-defined conversion to lvalue that we can use. */
426 rval_as_conversion
427 = build_type_conversion (reftype, expr);
429 if (rval_as_conversion && rval_as_conversion != error_mark_node
430 && real_lvalue_p (rval_as_conversion))
432 expr = rval_as_conversion;
433 rval_as_conversion = NULL_TREE;
434 intype = type;
435 can_convert_intype_to_type = 1;
439 if (((convtype & CONV_STATIC) && can_convert (intype, type))
440 || ((convtype & CONV_IMPLICIT) && can_convert_intype_to_type))
442 if (flags & LOOKUP_COMPLAIN)
444 tree ttl = TREE_TYPE (reftype);
445 tree ttr = lvalue_type (expr);
447 if (! real_lvalue_p (expr))
448 warn_ref_binding (reftype, intype, decl);
450 if (! (convtype & CONV_CONST)
451 && !at_least_as_qualified_p (ttl, ttr))
452 permerror ("conversion from %qT to %qT discards qualifiers",
453 ttr, reftype);
456 return build_up_reference (reftype, expr, flags, decl);
458 else if ((convtype & CONV_REINTERPRET) && lvalue_p (expr))
460 /* When casting an lvalue to a reference type, just convert into
461 a pointer to the new type and deference it. This is allowed
462 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
463 should be done directly (jason). (int &)ri ---> *(int*)&ri */
465 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
466 meant. */
467 if (TREE_CODE (intype) == POINTER_TYPE
468 && (comptypes (TREE_TYPE (intype), type,
469 COMPARE_BASE | COMPARE_DERIVED)))
470 warning (0, "casting %qT to %qT does not dereference pointer",
471 intype, reftype);
473 rval = build_unary_op (ADDR_EXPR, expr, 0);
474 if (rval != error_mark_node)
475 rval = convert_force (build_pointer_type (TREE_TYPE (reftype)),
476 rval, 0);
477 if (rval != error_mark_node)
478 rval = build1 (NOP_EXPR, reftype, rval);
480 else
482 rval = convert_for_initialization (NULL_TREE, type, expr, flags,
483 "converting", 0, 0);
484 if (rval == NULL_TREE || rval == error_mark_node)
485 return rval;
486 warn_ref_binding (reftype, intype, decl);
487 rval = build_up_reference (reftype, rval, flags, decl);
490 if (rval)
492 /* If we found a way to convert earlier, then use it. */
493 return rval;
496 if (flags & LOOKUP_COMPLAIN)
497 error ("cannot convert type %qT to type %qT", intype, reftype);
499 return error_mark_node;
502 /* We are using a reference VAL for its value. Bash that reference all the
503 way down to its lowest form. */
505 tree
506 convert_from_reference (tree val)
508 if (TREE_CODE (TREE_TYPE (val)) == REFERENCE_TYPE)
510 tree t = canonical_type_variant (TREE_TYPE (TREE_TYPE (val)));
511 tree ref = build1 (INDIRECT_REF, t, val);
513 /* We *must* set TREE_READONLY when dereferencing a pointer to const,
514 so that we get the proper error message if the result is used
515 to assign to. Also, &* is supposed to be a no-op. */
516 TREE_READONLY (ref) = CP_TYPE_CONST_P (t);
517 TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t);
518 TREE_SIDE_EFFECTS (ref)
519 = (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (val));
520 REFERENCE_REF_P (ref) = 1;
521 val = ref;
524 return val;
527 /* Really perform an lvalue-to-rvalue conversion, including copying an
528 argument of class type into a temporary. */
530 tree
531 force_rvalue (tree expr)
533 if (IS_AGGR_TYPE (TREE_TYPE (expr)) && TREE_CODE (expr) != TARGET_EXPR)
534 expr = ocp_convert (TREE_TYPE (expr), expr,
535 CONV_IMPLICIT|CONV_FORCE_TEMP, LOOKUP_NORMAL);
536 else
537 expr = decay_conversion (expr);
539 return expr;
542 /* C++ conversions, preference to static cast conversions. */
544 tree
545 cp_convert (tree type, tree expr)
547 return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL);
550 /* C++ equivalent of convert_and_check but using cp_convert as the
551 conversion function.
553 Convert EXPR to TYPE, warning about conversion problems with constants.
554 Invoke this function on every expression that is converted implicitly,
555 i.e. because of language rules and not because of an explicit cast. */
557 tree
558 cp_convert_and_check (tree type, tree expr)
560 tree result;
562 if (TREE_TYPE (expr) == type)
563 return expr;
565 result = cp_convert (type, expr);
567 if (!skip_evaluation && !TREE_OVERFLOW_P (expr) && result != error_mark_node)
568 warnings_for_convert_and_check (type, expr, result);
570 return result;
573 /* Conversion...
575 FLAGS indicates how we should behave. */
577 tree
578 ocp_convert (tree type, tree expr, int convtype, int flags)
580 tree e = expr;
581 enum tree_code code = TREE_CODE (type);
582 const char *invalid_conv_diag;
584 if (error_operand_p (e) || type == error_mark_node)
585 return error_mark_node;
587 complete_type (type);
588 complete_type (TREE_TYPE (expr));
590 if ((invalid_conv_diag
591 = targetm.invalid_conversion (TREE_TYPE (expr), type)))
593 error (invalid_conv_diag);
594 return error_mark_node;
597 e = integral_constant_value (e);
599 if (IS_AGGR_TYPE (type) && (convtype & CONV_FORCE_TEMP))
600 /* We need a new temporary; don't take this shortcut. */;
601 else if (same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (e)))
603 if (same_type_p (type, TREE_TYPE (e)))
604 /* The call to fold will not always remove the NOP_EXPR as
605 might be expected, since if one of the types is a typedef;
606 the comparison in fold is just equality of pointers, not a
607 call to comptypes. We don't call fold in this case because
608 that can result in infinite recursion; fold will call
609 convert, which will call ocp_convert, etc. */
610 return e;
611 /* For complex data types, we need to perform componentwise
612 conversion. */
613 else if (TREE_CODE (type) == COMPLEX_TYPE)
614 return fold_if_not_in_template (convert_to_complex (type, e));
615 else if (TREE_CODE (e) == TARGET_EXPR)
617 /* Don't build a NOP_EXPR of class type. Instead, change the
618 type of the temporary. */
619 TREE_TYPE (e) = TREE_TYPE (TARGET_EXPR_SLOT (e)) = type;
620 return e;
622 else
624 /* We shouldn't be treating objects of ADDRESSABLE type as
625 rvalues. */
626 gcc_assert (!TREE_ADDRESSABLE (type));
627 return fold_if_not_in_template (build_nop (type, e));
631 if (code == VOID_TYPE && (convtype & CONV_STATIC))
633 e = convert_to_void (e, /*implicit=*/NULL);
634 return e;
637 if (INTEGRAL_CODE_P (code))
639 tree intype = TREE_TYPE (e);
640 /* enum = enum, enum = int, enum = float, (enum)pointer are all
641 errors. */
642 if (TREE_CODE (type) == ENUMERAL_TYPE
643 && (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype)
644 || TREE_CODE (intype) == REAL_TYPE)
645 && ! (convtype & CONV_STATIC))
646 || TREE_CODE (intype) == POINTER_TYPE))
648 if (flags & LOOKUP_COMPLAIN)
649 permerror ("conversion from %q#T to %q#T", intype, type);
651 if (!flag_permissive)
652 return error_mark_node;
654 if (IS_AGGR_TYPE (intype))
656 tree rval;
657 rval = build_type_conversion (type, e);
658 if (rval)
659 return rval;
660 if (flags & LOOKUP_COMPLAIN)
661 error ("%q#T used where a %qT was expected", intype, type);
662 return error_mark_node;
664 if (code == BOOLEAN_TYPE)
665 return cp_truthvalue_conversion (e);
667 return fold_if_not_in_template (convert_to_integer (type, e));
669 if (POINTER_TYPE_P (type) || TYPE_PTR_TO_MEMBER_P (type))
670 return fold_if_not_in_template (cp_convert_to_pointer (type, e));
671 if (code == VECTOR_TYPE)
673 tree in_vtype = TREE_TYPE (e);
674 if (IS_AGGR_TYPE (in_vtype))
676 tree ret_val;
677 ret_val = build_type_conversion (type, e);
678 if (ret_val)
679 return ret_val;
680 if (flags & LOOKUP_COMPLAIN)
681 error ("%q#T used where a %qT was expected", in_vtype, type);
682 return error_mark_node;
684 return fold_if_not_in_template (convert_to_vector (type, e));
686 if (code == REAL_TYPE || code == COMPLEX_TYPE)
688 if (IS_AGGR_TYPE (TREE_TYPE (e)))
690 tree rval;
691 rval = build_type_conversion (type, e);
692 if (rval)
693 return rval;
694 else
695 if (flags & LOOKUP_COMPLAIN)
696 error ("%q#T used where a floating point value was expected",
697 TREE_TYPE (e));
699 if (code == REAL_TYPE)
700 return fold_if_not_in_template (convert_to_real (type, e));
701 else if (code == COMPLEX_TYPE)
702 return fold_if_not_in_template (convert_to_complex (type, e));
705 /* New C++ semantics: since assignment is now based on
706 memberwise copying, if the rhs type is derived from the
707 lhs type, then we may still do a conversion. */
708 if (IS_AGGR_TYPE_CODE (code))
710 tree dtype = TREE_TYPE (e);
711 tree ctor = NULL_TREE;
713 dtype = TYPE_MAIN_VARIANT (dtype);
715 /* Conversion between aggregate types. New C++ semantics allow
716 objects of derived type to be cast to objects of base type.
717 Old semantics only allowed this between pointers.
719 There may be some ambiguity between using a constructor
720 vs. using a type conversion operator when both apply. */
722 ctor = e;
724 if (abstract_virtuals_error (NULL_TREE, type))
725 return error_mark_node;
727 if ((flags & LOOKUP_ONLYCONVERTING)
728 && ! (IS_AGGR_TYPE (dtype) && DERIVED_FROM_P (type, dtype)))
729 /* For copy-initialization, first we create a temp of the proper type
730 with a user-defined conversion sequence, then we direct-initialize
731 the target with the temp (see [dcl.init]). */
732 ctor = build_user_type_conversion (type, ctor, flags);
733 else
734 ctor = build_special_member_call (NULL_TREE,
735 complete_ctor_identifier,
736 build_tree_list (NULL_TREE, ctor),
737 type, flags);
738 if (ctor)
739 return build_cplus_new (type, ctor);
742 if (flags & LOOKUP_COMPLAIN)
743 error ("conversion from %qT to non-scalar type %qT requested",
744 TREE_TYPE (expr), type);
745 return error_mark_node;
748 /* When an expression is used in a void context, its value is discarded and
749 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
750 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
751 in a void context. The C++ standard does not define what an `access' to an
752 object is, but there is reason to believe that it is the lvalue to rvalue
753 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
754 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
755 indicates that volatile semantics should be the same between C and C++
756 where ever possible. C leaves it implementation defined as to what
757 constitutes an access to a volatile. So, we interpret `*vp' as a read of
758 the volatile object `vp' points to, unless that is an incomplete type. For
759 volatile references we do not do this interpretation, because that would
760 make it impossible to ignore the reference return value from functions. We
761 issue warnings in the confusing cases.
763 IMPLICIT is tells us the context of an implicit void conversion. */
765 tree
766 convert_to_void (tree expr, const char *implicit)
768 if (expr == error_mark_node
769 || TREE_TYPE (expr) == error_mark_node)
770 return error_mark_node;
771 if (!TREE_TYPE (expr))
772 return expr;
773 if (invalid_nonstatic_memfn_p (expr))
774 return error_mark_node;
775 if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR)
777 error ("pseudo-destructor is not called");
778 return error_mark_node;
780 if (VOID_TYPE_P (TREE_TYPE (expr)))
781 return expr;
782 switch (TREE_CODE (expr))
784 case COND_EXPR:
786 /* The two parts of a cond expr might be separate lvalues. */
787 tree op1 = TREE_OPERAND (expr,1);
788 tree op2 = TREE_OPERAND (expr,2);
789 tree new_op1 = convert_to_void
790 (op1, (implicit && !TREE_SIDE_EFFECTS (op2)
791 ? "second operand of conditional" : NULL));
792 tree new_op2 = convert_to_void
793 (op2, (implicit && !TREE_SIDE_EFFECTS (op1)
794 ? "third operand of conditional" : NULL));
796 expr = build3 (COND_EXPR, TREE_TYPE (new_op1),
797 TREE_OPERAND (expr, 0), new_op1, new_op2);
798 break;
801 case COMPOUND_EXPR:
803 /* The second part of a compound expr contains the value. */
804 tree op1 = TREE_OPERAND (expr,1);
805 tree new_op1 = convert_to_void
806 (op1, (implicit && !TREE_NO_WARNING (expr)
807 ? "right-hand operand of comma" : NULL));
809 if (new_op1 != op1)
811 tree t = build2 (COMPOUND_EXPR, TREE_TYPE (new_op1),
812 TREE_OPERAND (expr, 0), new_op1);
813 expr = t;
816 break;
819 case NON_LVALUE_EXPR:
820 case NOP_EXPR:
821 /* These have already decayed to rvalue. */
822 break;
824 case CALL_EXPR: /* We have a special meaning for volatile void fn(). */
825 break;
827 case INDIRECT_REF:
829 tree type = TREE_TYPE (expr);
830 int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
831 == REFERENCE_TYPE;
832 int is_volatile = TYPE_VOLATILE (type);
833 int is_complete = COMPLETE_TYPE_P (complete_type (type));
835 /* Can't load the value if we don't know the type. */
836 if (is_volatile && !is_complete)
837 warning (0, "object of incomplete type %qT will not be accessed in %s",
838 type, implicit ? implicit : "void context");
839 /* Don't load the value if this is an implicit dereference, or if
840 the type needs to be handled by ctors/dtors. */
841 else if (is_volatile && (is_reference || TREE_ADDRESSABLE (type)))
842 warning (0, "object of type %qT will not be accessed in %s",
843 TREE_TYPE (TREE_OPERAND (expr, 0)),
844 implicit ? implicit : "void context");
845 if (is_reference || !is_volatile || !is_complete || TREE_ADDRESSABLE (type))
846 expr = TREE_OPERAND (expr, 0);
848 break;
851 case VAR_DECL:
853 /* External variables might be incomplete. */
854 tree type = TREE_TYPE (expr);
855 int is_complete = COMPLETE_TYPE_P (complete_type (type));
857 if (TYPE_VOLATILE (type) && !is_complete)
858 warning (0, "object %qE of incomplete type %qT will not be accessed in %s",
859 expr, type, implicit ? implicit : "void context");
860 break;
863 case TARGET_EXPR:
864 /* Don't bother with the temporary object returned from a function if
865 we don't use it and don't need to destroy it. We'll still
866 allocate space for it in expand_call or declare_return_variable,
867 but we don't need to track it through all the tree phases. */
868 if (TARGET_EXPR_IMPLICIT_P (expr)
869 && TYPE_HAS_TRIVIAL_DESTRUCTOR (TREE_TYPE (expr)))
871 tree init = TARGET_EXPR_INITIAL (expr);
872 if (TREE_CODE (init) == AGGR_INIT_EXPR
873 && !AGGR_INIT_VIA_CTOR_P (init))
875 tree fn = AGGR_INIT_EXPR_FN (init);
876 expr = build_call_array (TREE_TYPE (TREE_TYPE (TREE_TYPE (fn))),
878 aggr_init_expr_nargs (init),
879 AGGR_INIT_EXPR_ARGP (init));
882 break;
884 default:;
887 tree probe = expr;
889 if (TREE_CODE (probe) == ADDR_EXPR)
890 probe = TREE_OPERAND (expr, 0);
891 if (type_unknown_p (probe))
893 /* [over.over] enumerates the places where we can take the address
894 of an overloaded function, and this is not one of them. */
895 error ("%s cannot resolve address of overloaded function",
896 implicit ? implicit : "void cast");
897 expr = void_zero_node;
899 else if (implicit && probe == expr && is_overloaded_fn (probe))
901 /* Only warn when there is no &. */
902 warning (OPT_Waddress, "%s is a reference, not call, to function %qE",
903 implicit, expr);
904 if (TREE_CODE (expr) == COMPONENT_REF)
905 expr = TREE_OPERAND (expr, 0);
909 if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
911 if (implicit
912 && warn_unused_value
913 && !TREE_NO_WARNING (expr)
914 && !processing_template_decl)
916 /* The middle end does not warn about expressions that have
917 been explicitly cast to void, so we must do so here. */
918 if (!TREE_SIDE_EFFECTS (expr))
919 warning (OPT_Wunused_value, "%s has no effect", implicit);
920 else
922 tree e;
923 enum tree_code code;
924 enum tree_code_class class;
926 e = expr;
927 /* We might like to warn about (say) "(int) f()", as the
928 cast has no effect, but the compiler itself will
929 generate implicit conversions under some
930 circumstances. (For example a block copy will be
931 turned into a call to "__builtin_memcpy", with a
932 conversion of the return value to an appropriate
933 type.) So, to avoid false positives, we strip
934 conversions. Do not use STRIP_NOPs because it will
935 not strip conversions to "void", as that is not a
936 mode-preserving conversion. */
937 while (TREE_CODE (e) == NOP_EXPR)
938 e = TREE_OPERAND (e, 0);
940 code = TREE_CODE (e);
941 class = TREE_CODE_CLASS (code);
942 if (class == tcc_comparison
943 || class == tcc_unary
944 || (class == tcc_binary
945 && !(code == MODIFY_EXPR
946 || code == INIT_EXPR
947 || code == PREDECREMENT_EXPR
948 || code == PREINCREMENT_EXPR
949 || code == POSTDECREMENT_EXPR
950 || code == POSTINCREMENT_EXPR)))
951 warning (OPT_Wunused_value, "value computed is not used");
954 expr = build1 (CONVERT_EXPR, void_type_node, expr);
956 if (! TREE_SIDE_EFFECTS (expr))
957 expr = void_zero_node;
958 return expr;
961 /* Create an expression whose value is that of EXPR,
962 converted to type TYPE. The TREE_TYPE of the value
963 is always TYPE. This function implements all reasonable
964 conversions; callers should filter out those that are
965 not permitted by the language being compiled.
967 Most of this routine is from build_reinterpret_cast.
969 The back end cannot call cp_convert (what was convert) because
970 conversions to/from basetypes may involve memory references
971 (vbases) and adding or subtracting small values (multiple
972 inheritance), but it calls convert from the constant folding code
973 on subtrees of already built trees after it has ripped them apart.
975 Also, if we ever support range variables, we'll probably also have to
976 do a little bit more work. */
978 tree
979 convert (tree type, tree expr)
981 tree intype;
983 if (type == error_mark_node || expr == error_mark_node)
984 return error_mark_node;
986 intype = TREE_TYPE (expr);
988 if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype))
989 return fold_if_not_in_template (build_nop (type, expr));
991 return ocp_convert (type, expr, CONV_OLD_CONVERT,
992 LOOKUP_NORMAL|LOOKUP_NO_CONVERSION);
995 /* Like cp_convert, except permit conversions to take place which
996 are not normally allowed due to access restrictions
997 (such as conversion from sub-type to private super-type). */
999 tree
1000 convert_force (tree type, tree expr, int convtype)
1002 tree e = expr;
1003 enum tree_code code = TREE_CODE (type);
1005 if (code == REFERENCE_TYPE)
1006 return (fold_if_not_in_template
1007 (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN,
1008 NULL_TREE)));
1010 if (code == POINTER_TYPE)
1011 return fold_if_not_in_template (convert_to_pointer_force (type, e));
1013 /* From typeck.c convert_for_assignment */
1014 if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR
1015 && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE
1016 && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE)
1017 || integer_zerop (e)
1018 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e)))
1019 && TYPE_PTRMEMFUNC_P (type))
1020 /* compatible pointer to member functions. */
1021 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1,
1022 /*c_cast_p=*/1);
1024 return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL);
1027 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1028 exists, return the attempted conversion. This may
1029 return ERROR_MARK_NODE if the conversion is not
1030 allowed (references private members, etc).
1031 If no conversion exists, NULL_TREE is returned.
1033 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1034 object parameter, or by the second standard conversion sequence if
1035 that doesn't do it. This will probably wait for an overloading rewrite.
1036 (jason 8/9/95) */
1038 static tree
1039 build_type_conversion (tree xtype, tree expr)
1041 /* C++: check to see if we can convert this aggregate type
1042 into the required type. */
1043 return build_user_type_conversion (xtype, expr, LOOKUP_NORMAL);
1046 /* Convert the given EXPR to one of a group of types suitable for use in an
1047 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1048 which indicates which types are suitable. If COMPLAIN is true, complain
1049 about ambiguity; otherwise, the caller will deal with it. */
1051 tree
1052 build_expr_type_conversion (int desires, tree expr, bool 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 (OPT_Wconversion, "converting NULL to non-pointer type");
1063 basetype = TREE_TYPE (expr);
1065 if (basetype == error_mark_node)
1066 return error_mark_node;
1068 if (! IS_AGGR_TYPE (basetype))
1069 switch (TREE_CODE (basetype))
1071 case INTEGER_TYPE:
1072 if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
1073 return expr;
1074 /* else fall through... */
1076 case BOOLEAN_TYPE:
1077 return (desires & WANT_INT) ? expr : NULL_TREE;
1078 case ENUMERAL_TYPE:
1079 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1080 case REAL_TYPE:
1081 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1082 case POINTER_TYPE:
1083 return (desires & WANT_POINTER) ? expr : NULL_TREE;
1085 case FUNCTION_TYPE:
1086 case ARRAY_TYPE:
1087 return (desires & WANT_POINTER) ? decay_conversion (expr)
1088 : NULL_TREE;
1090 case VECTOR_TYPE:
1091 if ((desires & WANT_VECTOR) == 0)
1092 return NULL_TREE;
1093 switch (TREE_CODE (TREE_TYPE (basetype)))
1095 case INTEGER_TYPE:
1096 case BOOLEAN_TYPE:
1097 return (desires & WANT_INT) ? expr : NULL_TREE;
1098 case ENUMERAL_TYPE:
1099 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1100 case REAL_TYPE:
1101 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1102 default:
1103 return NULL_TREE;
1106 default:
1107 return NULL_TREE;
1110 /* The code for conversions from class type is currently only used for
1111 delete expressions. Other expressions are handled by build_new_op. */
1112 if (!complete_type_or_else (basetype, expr))
1113 return error_mark_node;
1114 if (!TYPE_HAS_CONVERSION (basetype))
1115 return NULL_TREE;
1117 for (conv = lookup_conversions (basetype); conv; conv = TREE_CHAIN (conv))
1119 int win = 0;
1120 tree candidate;
1121 tree cand = TREE_VALUE (conv);
1123 if (winner && winner == cand)
1124 continue;
1126 candidate = non_reference (TREE_TYPE (TREE_TYPE (cand)));
1128 switch (TREE_CODE (candidate))
1130 case BOOLEAN_TYPE:
1131 case INTEGER_TYPE:
1132 win = (desires & WANT_INT); break;
1133 case ENUMERAL_TYPE:
1134 win = (desires & WANT_ENUM); break;
1135 case REAL_TYPE:
1136 win = (desires & WANT_FLOAT); break;
1137 case POINTER_TYPE:
1138 win = (desires & WANT_POINTER); break;
1140 case VECTOR_TYPE:
1141 if ((desires & WANT_VECTOR) == 0)
1142 break;
1143 switch (TREE_CODE (TREE_TYPE (candidate)))
1145 case BOOLEAN_TYPE:
1146 case INTEGER_TYPE:
1147 win = (desires & WANT_INT); break;
1148 case ENUMERAL_TYPE:
1149 win = (desires & WANT_ENUM); break;
1150 case REAL_TYPE:
1151 win = (desires & WANT_FLOAT); break;
1152 default:
1153 break;
1155 break;
1157 default:
1158 break;
1161 if (win)
1163 if (winner)
1165 if (complain)
1167 error ("ambiguous default type conversion from %qT",
1168 basetype);
1169 error (" candidate conversions include %qD and %qD",
1170 winner, cand);
1172 return error_mark_node;
1174 else
1175 winner = cand;
1179 if (winner)
1181 tree type = non_reference (TREE_TYPE (TREE_TYPE (winner)));
1182 return build_user_type_conversion (type, expr, LOOKUP_NORMAL);
1185 return NULL_TREE;
1188 /* Implements integral promotion (4.1) and float->double promotion. */
1190 tree
1191 type_promotes_to (tree type)
1193 if (type == error_mark_node)
1194 return error_mark_node;
1196 type = TYPE_MAIN_VARIANT (type);
1198 /* bool always promotes to int (not unsigned), even if it's the same
1199 size. */
1200 if (type == boolean_type_node)
1201 type = integer_type_node;
1203 /* Normally convert enums to int, but convert wide enums to something
1204 wider. */
1205 else if (TREE_CODE (type) == ENUMERAL_TYPE
1206 || type == wchar_type_node)
1208 int precision = MAX (TYPE_PRECISION (type),
1209 TYPE_PRECISION (integer_type_node));
1210 tree totype = c_common_type_for_size (precision, 0);
1211 if (TYPE_UNSIGNED (type)
1212 && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype))
1213 type = c_common_type_for_size (precision, 1);
1214 else
1215 type = totype;
1217 else if (c_promoting_integer_type_p (type))
1219 /* Retain unsignedness if really not getting bigger. */
1220 if (TYPE_UNSIGNED (type)
1221 && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1222 type = unsigned_type_node;
1223 else
1224 type = integer_type_node;
1226 else if (type == float_type_node)
1227 type = double_type_node;
1229 return type;
1232 /* The routines below this point are carefully written to conform to
1233 the standard. They use the same terminology, and follow the rules
1234 closely. Although they are used only in pt.c at the moment, they
1235 should presumably be used everywhere in the future. */
1237 /* Attempt to perform qualification conversions on EXPR to convert it
1238 to TYPE. Return the resulting expression, or error_mark_node if
1239 the conversion was impossible. */
1241 tree
1242 perform_qualification_conversions (tree type, tree expr)
1244 tree expr_type;
1246 expr_type = TREE_TYPE (expr);
1248 if (same_type_p (type, expr_type))
1249 return expr;
1250 else if (TYPE_PTR_P (type) && TYPE_PTR_P (expr_type)
1251 && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (expr_type)))
1252 return build_nop (type, expr);
1253 else if (TYPE_PTR_TO_MEMBER_P (type)
1254 && TYPE_PTR_TO_MEMBER_P (expr_type)
1255 && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type),
1256 TYPE_PTRMEM_CLASS_TYPE (expr_type))
1257 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type),
1258 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type)))
1259 return build_nop (type, expr);
1260 else
1261 return error_mark_node;