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, 2008, 2009
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)
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. */
31 #include "coretypes.h"
42 static tree cp_convert_to_pointer (tree, tree);
43 static tree convert_to_pointer_force (tree, tree);
44 static tree build_type_conversion (tree, tree);
45 static tree build_up_reference (tree, tree, int, tree);
46 static void warn_ref_binding (tree, tree, tree);
48 /* Change of width--truncation and extension of integers or reals--
49 is represented with NOP_EXPR. Proper functioning of many things
50 assumes that no other conversions can be NOP_EXPRs.
52 Conversion between integer and pointer is represented with CONVERT_EXPR.
53 Converting integer to real uses FLOAT_EXPR
54 and real to integer uses FIX_TRUNC_EXPR.
56 Here is a list of all the functions that assume that widening and
57 narrowing is always done with a NOP_EXPR:
58 In convert.c, convert_to_integer.
59 In c-typeck.c, build_binary_op_nodefault (boolean ops),
60 and c_common_truthvalue_conversion.
61 In expr.c: expand_expr, for operands of a MULT_EXPR.
62 In fold-const.c: fold.
63 In tree.c: get_narrower and get_unwidened.
65 C++: in multiple-inheritance, converting between pointers may involve
66 adjusting them by a delta stored within the class definition. */
68 /* Subroutines of `convert'. */
70 /* if converting pointer to pointer
71 if dealing with classes, check for derived->base or vice versa
72 else if dealing with method pointers, delegate
74 else if converting class, pass off to build_type_conversion
75 else try C-style pointer conversion. */
78 cp_convert_to_pointer (tree type, tree expr)
80 tree intype = TREE_TYPE (expr);
83 if (intype == error_mark_node)
84 return error_mark_node;
86 if (MAYBE_CLASS_TYPE_P (intype))
88 intype = complete_type (intype);
89 if (!COMPLETE_TYPE_P (intype))
91 error ("can't convert from incomplete type %qT to %qT",
93 return error_mark_node;
96 rval = build_type_conversion (type, expr);
99 if (rval == error_mark_node)
100 error ("conversion of %qE from %qT to %qT is ambiguous",
106 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
107 if (TREE_CODE (type) == POINTER_TYPE
108 && (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
109 || VOID_TYPE_P (TREE_TYPE (type))))
111 if (TYPE_PTRMEMFUNC_P (intype)
112 || TREE_CODE (intype) == METHOD_TYPE)
113 return convert_member_func_to_ptr (type, expr);
114 if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
115 return build_nop (type, expr);
116 intype = TREE_TYPE (expr);
119 if (expr == error_mark_node)
120 return error_mark_node;
122 form = TREE_CODE (intype);
124 if (POINTER_TYPE_P (intype))
126 intype = TYPE_MAIN_VARIANT (intype);
128 if (TYPE_MAIN_VARIANT (type) != intype
129 && TREE_CODE (type) == POINTER_TYPE
130 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
131 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type))
132 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype))
133 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
135 enum tree_code code = PLUS_EXPR;
141 intype_class = TREE_TYPE (intype);
142 type_class = TREE_TYPE (type);
144 same_p = same_type_p (TYPE_MAIN_VARIANT (intype_class),
145 TYPE_MAIN_VARIANT (type_class));
147 /* Try derived to base conversion. */
149 binfo = lookup_base (intype_class, type_class, ba_check, NULL);
150 if (!same_p && !binfo)
152 /* Try base to derived conversion. */
153 binfo = lookup_base (type_class, intype_class, ba_check, NULL);
156 if (binfo == error_mark_node)
157 return error_mark_node;
161 expr = build_base_path (code, expr, binfo, 0);
162 /* Add any qualifier conversions. */
163 return build_nop (type, expr);
167 if (TYPE_PTRMEMFUNC_P (type))
169 error ("cannot convert %qE from type %qT to type %qT",
171 return error_mark_node;
174 return build_nop (type, expr);
176 else if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
177 || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
178 return convert_ptrmem (type, expr, /*allow_inverse_p=*/false,
180 else if (TYPE_PTRMEMFUNC_P (intype))
184 if (TREE_CODE (expr) == PTRMEM_CST)
185 return cp_convert_to_pointer (type,
186 PTRMEM_CST_MEMBER (expr));
187 else if (TREE_CODE (expr) == OFFSET_REF)
189 tree object = TREE_OPERAND (expr, 0);
190 return get_member_function_from_ptrfunc (&object,
191 TREE_OPERAND (expr, 1));
194 error ("cannot convert %qE from type %qT to type %qT",
196 return error_mark_node;
199 if (integer_zerop (expr))
201 if (TYPE_PTRMEMFUNC_P (type))
202 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0,
205 if (TYPE_PTRMEM_P (type))
207 /* A NULL pointer-to-member is represented by -1, not by
209 expr = build_int_cst_type (type, -1);
212 expr = build_int_cst (type, 0);
216 else if (TYPE_PTR_TO_MEMBER_P (type) && INTEGRAL_CODE_P (form))
218 error ("invalid conversion from %qT to %qT", intype, type);
219 return error_mark_node;
222 if (INTEGRAL_CODE_P (form))
224 if (TYPE_PRECISION (intype) == POINTER_SIZE)
225 return build1 (CONVERT_EXPR, type, expr);
226 expr = cp_convert (c_common_type_for_size (POINTER_SIZE, 0), expr);
227 /* Modes may be different but sizes should be the same. There
228 is supposed to be some integral type that is the same width
230 gcc_assert (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr)))
231 == GET_MODE_SIZE (TYPE_MODE (type)));
233 return convert_to_pointer (type, expr);
236 if (type_unknown_p (expr))
237 return instantiate_type (type, expr, tf_warning_or_error);
239 error ("cannot convert %qE from type %qT to type %qT",
241 return error_mark_node;
244 /* Like convert, except permit conversions to take place which
245 are not normally allowed due to access restrictions
246 (such as conversion from sub-type to private super-type). */
249 convert_to_pointer_force (tree type, tree expr)
251 tree intype = TREE_TYPE (expr);
252 enum tree_code form = TREE_CODE (intype);
254 if (form == POINTER_TYPE)
256 intype = TYPE_MAIN_VARIANT (intype);
258 if (TYPE_MAIN_VARIANT (type) != intype
259 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
260 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type))
261 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype))
262 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
264 enum tree_code code = PLUS_EXPR;
267 binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
271 binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
275 if (binfo == error_mark_node)
276 return error_mark_node;
279 expr = build_base_path (code, expr, binfo, 0);
280 if (expr == error_mark_node)
281 return error_mark_node;
282 /* Add any qualifier conversions. */
283 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)),
285 expr = build_nop (type, expr);
291 return cp_convert_to_pointer (type, expr);
294 /* We are passing something to a function which requires a reference.
295 The type we are interested in is in TYPE. The initial
296 value we have to begin with is in ARG.
298 FLAGS controls how we manage access checking.
299 DIRECT_BIND in FLAGS controls how any temporaries are generated.
300 If DIRECT_BIND is set, DECL is the reference we're binding to. */
303 build_up_reference (tree type, tree arg, int flags, tree decl)
306 tree argtype = TREE_TYPE (arg);
307 tree target_type = TREE_TYPE (type);
309 gcc_assert (TREE_CODE (type) == REFERENCE_TYPE);
311 if ((flags & DIRECT_BIND) && ! real_lvalue_p (arg))
313 /* Create a new temporary variable. We can't just use a TARGET_EXPR
314 here because it needs to live as long as DECL. */
317 arg = make_temporary_var_for_ref_to_temp (decl, TREE_TYPE (arg));
319 /* Process the initializer for the declaration. */
320 DECL_INITIAL (arg) = targ;
321 cp_finish_decl (arg, targ, /*init_const_expr_p=*/false, NULL_TREE,
322 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
324 else if (!(flags & DIRECT_BIND) && ! lvalue_p (arg))
325 return get_target_expr (arg);
327 /* If we had a way to wrap this up, and say, if we ever needed its
328 address, transform all occurrences of the register, into a memory
329 reference we could win better. */
330 rval = cp_build_unary_op (ADDR_EXPR, arg, 1, tf_warning_or_error);
331 if (rval == error_mark_node)
332 return error_mark_node;
334 if ((flags & LOOKUP_PROTECT)
335 && TYPE_MAIN_VARIANT (argtype) != TYPE_MAIN_VARIANT (target_type)
336 && MAYBE_CLASS_TYPE_P (argtype)
337 && MAYBE_CLASS_TYPE_P (target_type))
339 /* We go through lookup_base for the access control. */
340 tree binfo = lookup_base (argtype, target_type, ba_check, NULL);
341 if (binfo == error_mark_node)
342 return error_mark_node;
343 if (binfo == NULL_TREE)
344 return error_not_base_type (target_type, argtype);
345 rval = build_base_path (PLUS_EXPR, rval, binfo, 1);
349 = convert_to_pointer_force (build_pointer_type (target_type), rval);
350 return build_nop (type, rval);
353 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
354 INTYPE is the original rvalue type and DECL is an optional _DECL node
357 [dcl.init.ref] says that if an rvalue is used to
358 initialize a reference, then the reference must be to a
359 non-volatile const type. */
362 warn_ref_binding (tree reftype, tree intype, tree decl)
364 tree ttl = TREE_TYPE (reftype);
366 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl))
370 if (CP_TYPE_VOLATILE_P (ttl) && decl)
371 msg = G_("initialization of volatile reference type %q#T from "
372 "rvalue of type %qT");
373 else if (CP_TYPE_VOLATILE_P (ttl))
374 msg = G_("conversion to volatile reference type %q#T "
375 "from rvalue of type %qT");
377 msg = G_("initialization of non-const reference type %q#T from "
378 "rvalue of type %qT");
380 msg = G_("conversion to non-const reference type %q#T from "
381 "rvalue of type %qT");
383 permerror (input_location, msg, reftype, intype);
387 /* For C++: Only need to do one-level references, but cannot
388 get tripped up on signed/unsigned differences.
390 DECL is either NULL_TREE or the _DECL node for a reference that is being
391 initialized. It can be error_mark_node if we don't know the _DECL but
392 we know it's an initialization. */
395 convert_to_reference (tree reftype, tree expr, int convtype,
396 int flags, tree decl)
398 tree type = TYPE_MAIN_VARIANT (TREE_TYPE (reftype));
400 tree rval = NULL_TREE;
401 tree rval_as_conversion = NULL_TREE;
402 bool can_convert_intype_to_type;
404 if (TREE_CODE (type) == FUNCTION_TYPE
405 && TREE_TYPE (expr) == unknown_type_node)
406 expr = instantiate_type (type, expr,
407 (flags & LOOKUP_COMPLAIN)
408 ? tf_warning_or_error : tf_none);
410 if (expr == error_mark_node)
411 return error_mark_node;
413 intype = TREE_TYPE (expr);
415 gcc_assert (TREE_CODE (intype) != REFERENCE_TYPE);
416 gcc_assert (TREE_CODE (reftype) == REFERENCE_TYPE);
418 intype = TYPE_MAIN_VARIANT (intype);
420 can_convert_intype_to_type = can_convert (type, intype);
421 if (!can_convert_intype_to_type
422 && (convtype & CONV_IMPLICIT) && MAYBE_CLASS_TYPE_P (intype)
423 && ! (flags & LOOKUP_NO_CONVERSION))
425 /* Look for a user-defined conversion to lvalue that we can use. */
428 = build_type_conversion (reftype, expr);
430 if (rval_as_conversion && rval_as_conversion != error_mark_node
431 && real_lvalue_p (rval_as_conversion))
433 expr = rval_as_conversion;
434 rval_as_conversion = NULL_TREE;
436 can_convert_intype_to_type = 1;
440 if (((convtype & CONV_STATIC) && can_convert (intype, type))
441 || ((convtype & CONV_IMPLICIT) && can_convert_intype_to_type))
443 if (flags & LOOKUP_COMPLAIN)
445 tree ttl = TREE_TYPE (reftype);
446 tree ttr = lvalue_type (expr);
448 if (! real_lvalue_p (expr))
449 warn_ref_binding (reftype, intype, decl);
451 if (! (convtype & CONV_CONST)
452 && !at_least_as_qualified_p (ttl, ttr))
453 permerror (input_location, "conversion from %qT to %qT discards qualifiers",
457 return build_up_reference (reftype, expr, flags, decl);
459 else if ((convtype & CONV_REINTERPRET) && lvalue_p (expr))
461 /* When casting an lvalue to a reference type, just convert into
462 a pointer to the new type and deference it. This is allowed
463 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
464 should be done directly (jason). (int &)ri ---> *(int*)&ri */
466 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
468 if (TREE_CODE (intype) == POINTER_TYPE
469 && (comptypes (TREE_TYPE (intype), type,
470 COMPARE_BASE | COMPARE_DERIVED)))
471 warning (0, "casting %qT to %qT does not dereference pointer",
474 rval = cp_build_unary_op (ADDR_EXPR, expr, 0, tf_warning_or_error);
475 if (rval != error_mark_node)
476 rval = convert_force (build_pointer_type (TREE_TYPE (reftype)),
478 if (rval != error_mark_node)
479 rval = build1 (NOP_EXPR, reftype, rval);
483 rval = convert_for_initialization (NULL_TREE, type, expr, flags,
485 tf_warning_or_error);
486 if (rval == NULL_TREE || rval == error_mark_node)
488 warn_ref_binding (reftype, intype, decl);
489 rval = build_up_reference (reftype, rval, flags, decl);
494 /* If we found a way to convert earlier, then use it. */
498 if (flags & LOOKUP_COMPLAIN)
499 error ("cannot convert type %qT to type %qT", intype, reftype);
501 return error_mark_node;
504 /* We are using a reference VAL for its value. Bash that reference all the
505 way down to its lowest form. */
508 convert_from_reference (tree val)
511 && TREE_CODE (TREE_TYPE (val)) == REFERENCE_TYPE)
513 tree t = TREE_TYPE (TREE_TYPE (val));
514 tree ref = build1 (INDIRECT_REF, t, val);
516 /* We *must* set TREE_READONLY when dereferencing a pointer to const,
517 so that we get the proper error message if the result is used
518 to assign to. Also, &* is supposed to be a no-op. */
519 TREE_READONLY (ref) = CP_TYPE_CONST_P (t);
520 TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t);
521 TREE_SIDE_EFFECTS (ref)
522 = (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (val));
523 REFERENCE_REF_P (ref) = 1;
530 /* Really perform an lvalue-to-rvalue conversion, including copying an
531 argument of class type into a temporary. */
534 force_rvalue (tree expr)
536 if (MAYBE_CLASS_TYPE_P (TREE_TYPE (expr)) && TREE_CODE (expr) != TARGET_EXPR)
537 expr = ocp_convert (TREE_TYPE (expr), expr,
538 CONV_IMPLICIT|CONV_FORCE_TEMP, LOOKUP_NORMAL);
540 expr = decay_conversion (expr);
546 /* Fold away simple conversions, but make sure the result is an rvalue. */
549 cp_fold_convert (tree type, tree expr)
551 return rvalue (fold_convert (type, expr));
554 /* C++ conversions, preference to static cast conversions. */
557 cp_convert (tree type, tree expr)
559 return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL);
562 /* C++ equivalent of convert_and_check but using cp_convert as the
565 Convert EXPR to TYPE, warning about conversion problems with constants.
566 Invoke this function on every expression that is converted implicitly,
567 i.e. because of language rules and not because of an explicit cast. */
570 cp_convert_and_check (tree type, tree expr)
574 if (TREE_TYPE (expr) == type)
577 result = cp_convert (type, expr);
579 if (c_inhibit_evaluation_warnings == 0
580 && !TREE_OVERFLOW_P (expr)
581 && result != error_mark_node)
582 warnings_for_convert_and_check (type, expr, result);
589 FLAGS indicates how we should behave. */
592 ocp_convert (tree type, tree expr, int convtype, int flags)
595 enum tree_code code = TREE_CODE (type);
596 const char *invalid_conv_diag;
599 if (error_operand_p (e) || type == error_mark_node)
600 return error_mark_node;
602 complete_type (type);
603 complete_type (TREE_TYPE (expr));
605 if ((invalid_conv_diag
606 = targetm.invalid_conversion (TREE_TYPE (expr), type)))
608 error (invalid_conv_diag);
609 return error_mark_node;
612 e = integral_constant_value (e);
613 if (error_operand_p (e))
614 return error_mark_node;
616 if (MAYBE_CLASS_TYPE_P (type) && (convtype & CONV_FORCE_TEMP))
617 /* We need a new temporary; don't take this shortcut. */;
618 else if (same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (e)))
620 if (same_type_p (type, TREE_TYPE (e)))
621 /* The call to fold will not always remove the NOP_EXPR as
622 might be expected, since if one of the types is a typedef;
623 the comparison in fold is just equality of pointers, not a
624 call to comptypes. We don't call fold in this case because
625 that can result in infinite recursion; fold will call
626 convert, which will call ocp_convert, etc. */
628 /* For complex data types, we need to perform componentwise
630 else if (TREE_CODE (type) == COMPLEX_TYPE)
631 return fold_if_not_in_template (convert_to_complex (type, e));
632 else if (TREE_CODE (e) == TARGET_EXPR)
634 /* Don't build a NOP_EXPR of class type. Instead, change the
635 type of the temporary. */
636 TREE_TYPE (e) = TREE_TYPE (TARGET_EXPR_SLOT (e)) = type;
641 /* We shouldn't be treating objects of ADDRESSABLE type as
643 gcc_assert (!TREE_ADDRESSABLE (type));
644 return fold_if_not_in_template (build_nop (type, e));
648 e1 = targetm.convert_to_type (type, e);
652 if (code == VOID_TYPE && (convtype & CONV_STATIC))
654 e = convert_to_void (e, /*implicit=*/NULL, tf_warning_or_error);
658 if (INTEGRAL_CODE_P (code))
660 tree intype = TREE_TYPE (e);
662 if (TREE_CODE (type) == ENUMERAL_TYPE)
664 /* enum = enum, enum = int, enum = float, (enum)pointer are all
666 if (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype)
667 || TREE_CODE (intype) == REAL_TYPE)
668 && ! (convtype & CONV_STATIC))
669 || TREE_CODE (intype) == POINTER_TYPE)
671 if (flags & LOOKUP_COMPLAIN)
672 permerror (input_location, "conversion from %q#T to %q#T", intype, type);
674 if (!flag_permissive)
675 return error_mark_node;
678 /* [expr.static.cast]
680 8. A value of integral or enumeration type can be explicitly
681 converted to an enumeration type. The value is unchanged if
682 the original value is within the range of the enumeration
683 values. Otherwise, the resulting enumeration value is
685 if (TREE_CODE (expr) == INTEGER_CST && !int_fits_type_p (expr, type))
686 warning (OPT_Wconversion,
687 "the result of the conversion is unspecified because "
688 "%qE is outside the range of type %qT",
691 if (MAYBE_CLASS_TYPE_P (intype))
694 rval = build_type_conversion (type, e);
697 if (flags & LOOKUP_COMPLAIN)
698 error ("%q#T used where a %qT was expected", intype, type);
699 return error_mark_node;
701 if (code == BOOLEAN_TYPE)
702 return cp_truthvalue_conversion (e);
704 return fold_if_not_in_template (convert_to_integer (type, e));
706 if (POINTER_TYPE_P (type) || TYPE_PTR_TO_MEMBER_P (type))
707 return fold_if_not_in_template (cp_convert_to_pointer (type, e));
708 if (code == VECTOR_TYPE)
710 tree in_vtype = TREE_TYPE (e);
711 if (MAYBE_CLASS_TYPE_P (in_vtype))
714 ret_val = build_type_conversion (type, e);
717 if (flags & LOOKUP_COMPLAIN)
718 error ("%q#T used where a %qT was expected", in_vtype, type);
719 return error_mark_node;
721 return fold_if_not_in_template (convert_to_vector (type, e));
723 if (code == REAL_TYPE || code == COMPLEX_TYPE)
725 if (MAYBE_CLASS_TYPE_P (TREE_TYPE (e)))
728 rval = build_type_conversion (type, e);
732 if (flags & LOOKUP_COMPLAIN)
733 error ("%q#T used where a floating point value was expected",
736 if (code == REAL_TYPE)
737 return fold_if_not_in_template (convert_to_real (type, e));
738 else if (code == COMPLEX_TYPE)
739 return fold_if_not_in_template (convert_to_complex (type, e));
742 /* New C++ semantics: since assignment is now based on
743 memberwise copying, if the rhs type is derived from the
744 lhs type, then we may still do a conversion. */
745 if (RECORD_OR_UNION_CODE_P (code))
747 tree dtype = TREE_TYPE (e);
748 tree ctor = NULL_TREE;
750 dtype = TYPE_MAIN_VARIANT (dtype);
752 /* Conversion between aggregate types. New C++ semantics allow
753 objects of derived type to be cast to objects of base type.
754 Old semantics only allowed this between pointers.
756 There may be some ambiguity between using a constructor
757 vs. using a type conversion operator when both apply. */
761 if (abstract_virtuals_error (NULL_TREE, type))
762 return error_mark_node;
764 if (BRACE_ENCLOSED_INITIALIZER_P (ctor))
765 ctor = perform_implicit_conversion (type, ctor, tf_warning_or_error);
766 else if ((flags & LOOKUP_ONLYCONVERTING)
767 && ! (CLASS_TYPE_P (dtype) && DERIVED_FROM_P (type, dtype)))
768 /* For copy-initialization, first we create a temp of the proper type
769 with a user-defined conversion sequence, then we direct-initialize
770 the target with the temp (see [dcl.init]). */
771 ctor = build_user_type_conversion (type, ctor, flags);
774 VEC(tree,gc) *ctor_vec = make_tree_vector_single (ctor);
775 ctor = build_special_member_call (NULL_TREE,
776 complete_ctor_identifier,
779 tf_warning_or_error);
780 release_tree_vector (ctor_vec);
783 return build_cplus_new (type, ctor);
786 if (flags & LOOKUP_COMPLAIN)
788 /* If the conversion failed and expr was an invalid use of pointer to
789 member function, try to report a meaningful error. */
790 if (invalid_nonstatic_memfn_p (expr, tf_warning_or_error))
791 /* We displayed the error message. */;
793 error ("conversion from %qT to non-scalar type %qT requested",
794 TREE_TYPE (expr), type);
796 return error_mark_node;
799 /* When an expression is used in a void context, its value is discarded and
800 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
801 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
802 in a void context. The C++ standard does not define what an `access' to an
803 object is, but there is reason to believe that it is the lvalue to rvalue
804 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
805 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
806 indicates that volatile semantics should be the same between C and C++
807 where ever possible. C leaves it implementation defined as to what
808 constitutes an access to a volatile. So, we interpret `*vp' as a read of
809 the volatile object `vp' points to, unless that is an incomplete type. For
810 volatile references we do not do this interpretation, because that would
811 make it impossible to ignore the reference return value from functions. We
812 issue warnings in the confusing cases.
814 IMPLICIT is non-NULL iff an expression is being implicitly converted; it
815 is NULL when the user is explicitly converting an expression to void via
816 a cast. When non-NULL, IMPLICIT is a string indicating the context of
817 the implicit conversion. */
820 convert_to_void (tree expr, const char *implicit, tsubst_flags_t complain)
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 (invalid_nonstatic_memfn_p (expr, complain))
828 return error_mark_node;
829 if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR)
831 if (complain & tf_error)
832 error ("pseudo-destructor is not called");
833 return error_mark_node;
835 if (VOID_TYPE_P (TREE_TYPE (expr)))
837 switch (TREE_CODE (expr))
841 /* The two parts of a cond expr might be separate lvalues. */
842 tree op1 = TREE_OPERAND (expr,1);
843 tree op2 = TREE_OPERAND (expr,2);
844 bool side_effects = TREE_SIDE_EFFECTS (op1) || TREE_SIDE_EFFECTS (op2);
845 tree new_op1 = convert_to_void
846 (op1, (implicit && !side_effects
847 ? "second operand of conditional" : NULL), complain);
848 tree new_op2 = convert_to_void
849 (op2, (implicit && !side_effects
850 ? "third operand of conditional" : NULL), complain);
852 expr = build3 (COND_EXPR, TREE_TYPE (new_op1),
853 TREE_OPERAND (expr, 0), new_op1, new_op2);
859 /* The second part of a compound expr contains the value. */
860 tree op1 = TREE_OPERAND (expr,1);
861 tree new_op1 = convert_to_void
862 (op1, (implicit && !TREE_NO_WARNING (expr)
863 ? "right-hand operand of comma" : NULL), complain);
867 tree t = build2 (COMPOUND_EXPR, TREE_TYPE (new_op1),
868 TREE_OPERAND (expr, 0), new_op1);
875 case NON_LVALUE_EXPR:
877 /* These have already decayed to rvalue. */
880 case CALL_EXPR: /* We have a special meaning for volatile void fn(). */
885 tree type = TREE_TYPE (expr);
886 int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
888 int is_volatile = TYPE_VOLATILE (type);
889 int is_complete = COMPLETE_TYPE_P (complete_type (type));
891 /* Can't load the value if we don't know the type. */
892 if (is_volatile && !is_complete)
894 if (complain & tf_warning)
895 warning (0, "object of incomplete type %qT will not be accessed in %s",
896 type, implicit ? implicit : "void context");
898 /* Don't load the value if this is an implicit dereference, or if
899 the type needs to be handled by ctors/dtors. */
900 else if (is_volatile && (is_reference || TREE_ADDRESSABLE (type)))
902 if (complain & tf_warning)
903 warning (0, "object of type %qT will not be accessed in %s",
904 TREE_TYPE (TREE_OPERAND (expr, 0)),
905 implicit ? implicit : "void context");
907 if (is_reference || !is_volatile || !is_complete || TREE_ADDRESSABLE (type))
909 /* Emit a warning (if enabled) when the "effect-less" INDIRECT_REF
910 operation is stripped off. Note that we don't warn about
911 - an expression with TREE_NO_WARNING set. (For an example of
912 such expressions, see build_over_call in call.c.)
913 - automatic dereferencing of references, since the user cannot
914 control it. (See also warn_if_unused_value() in stmt.c.) */
915 if (warn_unused_value
917 && (complain & tf_warning)
918 && !TREE_NO_WARNING (expr)
920 warning (OPT_Wunused_value, "value computed is not used");
921 expr = TREE_OPERAND (expr, 0);
929 /* External variables might be incomplete. */
930 tree type = TREE_TYPE (expr);
931 int is_complete = COMPLETE_TYPE_P (complete_type (type));
933 if (TYPE_VOLATILE (type) && !is_complete && (complain & tf_warning))
934 warning (0, "object %qE of incomplete type %qT will not be accessed in %s",
935 expr, type, implicit ? implicit : "void context");
940 /* Don't bother with the temporary object returned from a function if
941 we don't use it and don't need to destroy it. We'll still
942 allocate space for it in expand_call or declare_return_variable,
943 but we don't need to track it through all the tree phases. */
944 if (TARGET_EXPR_IMPLICIT_P (expr)
945 && TYPE_HAS_TRIVIAL_DESTRUCTOR (TREE_TYPE (expr)))
947 tree init = TARGET_EXPR_INITIAL (expr);
948 if (TREE_CODE (init) == AGGR_INIT_EXPR
949 && !AGGR_INIT_VIA_CTOR_P (init))
951 tree fn = AGGR_INIT_EXPR_FN (init);
952 expr = build_call_array_loc (input_location,
953 TREE_TYPE (TREE_TYPE (TREE_TYPE (fn))),
955 aggr_init_expr_nargs (init),
956 AGGR_INIT_EXPR_ARGP (init));
963 expr = resolve_nondeduced_context (expr);
967 if (TREE_CODE (probe) == ADDR_EXPR)
968 probe = TREE_OPERAND (expr, 0);
969 if (type_unknown_p (probe))
971 /* [over.over] enumerates the places where we can take the address
972 of an overloaded function, and this is not one of them. */
973 if (complain & tf_error)
974 error ("%s cannot resolve address of overloaded function",
975 implicit ? implicit : "void cast");
977 return error_mark_node;
978 expr = void_zero_node;
980 else if (implicit && probe == expr && is_overloaded_fn (probe))
982 /* Only warn when there is no &. */
983 if (complain & tf_warning)
984 warning (OPT_Waddress, "%s is a reference, not call, to function %qE",
986 if (TREE_CODE (expr) == COMPONENT_REF)
987 expr = TREE_OPERAND (expr, 0);
991 if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
995 && !TREE_NO_WARNING (expr)
996 && !processing_template_decl)
998 /* The middle end does not warn about expressions that have
999 been explicitly cast to void, so we must do so here. */
1000 if (!TREE_SIDE_EFFECTS (expr)) {
1001 if (complain & tf_warning)
1002 warning (OPT_Wunused_value, "%s has no effect", implicit);
1007 enum tree_code code;
1008 enum tree_code_class tclass;
1011 /* We might like to warn about (say) "(int) f()", as the
1012 cast has no effect, but the compiler itself will
1013 generate implicit conversions under some
1014 circumstances. (For example a block copy will be
1015 turned into a call to "__builtin_memcpy", with a
1016 conversion of the return value to an appropriate
1017 type.) So, to avoid false positives, we strip
1018 conversions. Do not use STRIP_NOPs because it will
1019 not strip conversions to "void", as that is not a
1020 mode-preserving conversion. */
1021 while (TREE_CODE (e) == NOP_EXPR)
1022 e = TREE_OPERAND (e, 0);
1024 code = TREE_CODE (e);
1025 tclass = TREE_CODE_CLASS (code);
1026 if ((tclass == tcc_comparison
1027 || tclass == tcc_unary
1028 || (tclass == tcc_binary
1029 && !(code == MODIFY_EXPR
1030 || code == INIT_EXPR
1031 || code == PREDECREMENT_EXPR
1032 || code == PREINCREMENT_EXPR
1033 || code == POSTDECREMENT_EXPR
1034 || code == POSTINCREMENT_EXPR)))
1035 && (complain & tf_warning))
1036 warning (OPT_Wunused_value, "value computed is not used");
1039 expr = build1 (CONVERT_EXPR, void_type_node, expr);
1041 if (! TREE_SIDE_EFFECTS (expr))
1042 expr = void_zero_node;
1046 /* Create an expression whose value is that of EXPR,
1047 converted to type TYPE. The TREE_TYPE of the value
1048 is always TYPE. This function implements all reasonable
1049 conversions; callers should filter out those that are
1050 not permitted by the language being compiled.
1052 Most of this routine is from build_reinterpret_cast.
1054 The back end cannot call cp_convert (what was convert) because
1055 conversions to/from basetypes may involve memory references
1056 (vbases) and adding or subtracting small values (multiple
1057 inheritance), but it calls convert from the constant folding code
1058 on subtrees of already built trees after it has ripped them apart.
1060 Also, if we ever support range variables, we'll probably also have to
1061 do a little bit more work. */
1064 convert (tree type, tree expr)
1068 if (type == error_mark_node || expr == error_mark_node)
1069 return error_mark_node;
1071 intype = TREE_TYPE (expr);
1073 if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype))
1074 return fold_if_not_in_template (build_nop (type, expr));
1076 return ocp_convert (type, expr, CONV_OLD_CONVERT,
1077 LOOKUP_NORMAL|LOOKUP_NO_CONVERSION);
1080 /* Like cp_convert, except permit conversions to take place which
1081 are not normally allowed due to access restrictions
1082 (such as conversion from sub-type to private super-type). */
1085 convert_force (tree type, tree expr, int convtype)
1088 enum tree_code code = TREE_CODE (type);
1090 if (code == REFERENCE_TYPE)
1091 return (fold_if_not_in_template
1092 (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN,
1095 if (code == POINTER_TYPE)
1096 return fold_if_not_in_template (convert_to_pointer_force (type, e));
1098 /* From typeck.c convert_for_assignment */
1099 if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR
1100 && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE
1101 && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE)
1102 || integer_zerop (e)
1103 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e)))
1104 && TYPE_PTRMEMFUNC_P (type))
1105 /* compatible pointer to member functions. */
1106 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1,
1109 return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL);
1112 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1113 exists, return the attempted conversion. This may
1114 return ERROR_MARK_NODE if the conversion is not
1115 allowed (references private members, etc).
1116 If no conversion exists, NULL_TREE is returned.
1118 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1119 object parameter, or by the second standard conversion sequence if
1120 that doesn't do it. This will probably wait for an overloading rewrite.
1124 build_type_conversion (tree xtype, tree expr)
1126 /* C++: check to see if we can convert this aggregate type
1127 into the required type. */
1128 return build_user_type_conversion (xtype, expr, LOOKUP_NORMAL);
1131 /* Convert the given EXPR to one of a group of types suitable for use in an
1132 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1133 which indicates which types are suitable. If COMPLAIN is true, complain
1134 about ambiguity; otherwise, the caller will deal with it. */
1137 build_expr_type_conversion (int desires, tree expr, bool complain)
1139 tree basetype = TREE_TYPE (expr);
1140 tree conv = NULL_TREE;
1141 tree winner = NULL_TREE;
1143 if (expr == null_node
1144 && (desires & WANT_INT)
1145 && !(desires & WANT_NULL))
1146 warning_at (input_location, OPT_Wconversion_null,
1147 "converting NULL to non-pointer type");
1149 basetype = TREE_TYPE (expr);
1151 if (basetype == error_mark_node)
1152 return error_mark_node;
1154 if (! MAYBE_CLASS_TYPE_P (basetype))
1155 switch (TREE_CODE (basetype))
1158 if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
1160 /* else fall through... */
1163 return (desires & WANT_INT) ? expr : NULL_TREE;
1165 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1167 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1169 return (desires & WANT_POINTER) ? expr : NULL_TREE;
1173 return (desires & WANT_POINTER) ? decay_conversion (expr)
1178 if ((desires & WANT_VECTOR_OR_COMPLEX) == 0)
1180 switch (TREE_CODE (TREE_TYPE (basetype)))
1184 return (desires & WANT_INT) ? expr : NULL_TREE;
1186 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1188 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1197 /* The code for conversions from class type is currently only used for
1198 delete expressions. Other expressions are handled by build_new_op. */
1199 if (!complete_type_or_else (basetype, expr))
1200 return error_mark_node;
1201 if (!TYPE_HAS_CONVERSION (basetype))
1204 for (conv = lookup_conversions (basetype, /*lookup_template_convs_p=*/true);
1206 conv = TREE_CHAIN (conv))
1210 tree cand = TREE_VALUE (conv);
1211 cand = OVL_CURRENT (cand);
1213 if (winner && winner == cand)
1216 if (DECL_NONCONVERTING_P (cand))
1219 candidate = non_reference (TREE_TYPE (TREE_TYPE (cand)));
1221 switch (TREE_CODE (candidate))
1225 win = (desires & WANT_INT); break;
1227 win = (desires & WANT_ENUM); break;
1229 win = (desires & WANT_FLOAT); break;
1231 win = (desires & WANT_POINTER); break;
1235 if ((desires & WANT_VECTOR_OR_COMPLEX) == 0)
1237 switch (TREE_CODE (TREE_TYPE (candidate)))
1241 win = (desires & WANT_INT); break;
1243 win = (desires & WANT_ENUM); break;
1245 win = (desires & WANT_FLOAT); break;
1261 error ("ambiguous default type conversion from %qT",
1263 error (" candidate conversions include %qD and %qD",
1266 return error_mark_node;
1275 tree type = non_reference (TREE_TYPE (TREE_TYPE (winner)));
1276 return build_user_type_conversion (type, expr, LOOKUP_NORMAL);
1282 /* Implements integral promotion (4.1) and float->double promotion. */
1285 type_promotes_to (tree type)
1289 if (type == error_mark_node)
1290 return error_mark_node;
1292 type = TYPE_MAIN_VARIANT (type);
1294 /* Check for promotions of target-defined types first. */
1295 promoted_type = targetm.promoted_type (type);
1297 return promoted_type;
1299 /* bool always promotes to int (not unsigned), even if it's the same
1301 if (TREE_CODE (type) == BOOLEAN_TYPE)
1302 type = integer_type_node;
1304 /* Normally convert enums to int, but convert wide enums to something
1306 else if (TREE_CODE (type) == ENUMERAL_TYPE
1307 || type == char16_type_node
1308 || type == char32_type_node
1309 || type == wchar_type_node)
1311 int precision = MAX (TYPE_PRECISION (type),
1312 TYPE_PRECISION (integer_type_node));
1313 tree totype = c_common_type_for_size (precision, 0);
1314 if (TYPE_UNSIGNED (type)
1315 && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype))
1316 type = c_common_type_for_size (precision, 1);
1320 else if (c_promoting_integer_type_p (type))
1322 /* Retain unsignedness if really not getting bigger. */
1323 if (TYPE_UNSIGNED (type)
1324 && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1325 type = unsigned_type_node;
1327 type = integer_type_node;
1329 else if (type == float_type_node)
1330 type = double_type_node;
1335 /* The routines below this point are carefully written to conform to
1336 the standard. They use the same terminology, and follow the rules
1337 closely. Although they are used only in pt.c at the moment, they
1338 should presumably be used everywhere in the future. */
1340 /* Attempt to perform qualification conversions on EXPR to convert it
1341 to TYPE. Return the resulting expression, or error_mark_node if
1342 the conversion was impossible. */
1345 perform_qualification_conversions (tree type, tree expr)
1349 expr_type = TREE_TYPE (expr);
1351 if (same_type_p (type, expr_type))
1353 else if (TYPE_PTR_P (type) && TYPE_PTR_P (expr_type)
1354 && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (expr_type)))
1355 return build_nop (type, expr);
1356 else if (TYPE_PTR_TO_MEMBER_P (type)
1357 && TYPE_PTR_TO_MEMBER_P (expr_type)
1358 && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type),
1359 TYPE_PTRMEM_CLASS_TYPE (expr_type))
1360 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type),
1361 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type)))
1362 return build_nop (type, expr);
1364 return error_mark_node;