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);
614 if (MAYBE_CLASS_TYPE_P (type) && (convtype & CONV_FORCE_TEMP))
615 /* We need a new temporary; don't take this shortcut. */;
616 else if (same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (e)))
618 if (same_type_p (type, TREE_TYPE (e)))
619 /* The call to fold will not always remove the NOP_EXPR as
620 might be expected, since if one of the types is a typedef;
621 the comparison in fold is just equality of pointers, not a
622 call to comptypes. We don't call fold in this case because
623 that can result in infinite recursion; fold will call
624 convert, which will call ocp_convert, etc. */
626 /* For complex data types, we need to perform componentwise
628 else if (TREE_CODE (type) == COMPLEX_TYPE)
629 return fold_if_not_in_template (convert_to_complex (type, e));
630 else if (TREE_CODE (e) == TARGET_EXPR)
632 /* Don't build a NOP_EXPR of class type. Instead, change the
633 type of the temporary. */
634 TREE_TYPE (e) = TREE_TYPE (TARGET_EXPR_SLOT (e)) = type;
639 /* We shouldn't be treating objects of ADDRESSABLE type as
641 gcc_assert (!TREE_ADDRESSABLE (type));
642 return fold_if_not_in_template (build_nop (type, e));
646 e1 = targetm.convert_to_type (type, e);
650 if (code == VOID_TYPE && (convtype & CONV_STATIC))
652 e = convert_to_void (e, /*implicit=*/NULL, tf_warning_or_error);
656 if (INTEGRAL_CODE_P (code))
658 tree intype = TREE_TYPE (e);
660 if (TREE_CODE (type) == ENUMERAL_TYPE)
662 /* enum = enum, enum = int, enum = float, (enum)pointer are all
664 if (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype)
665 || TREE_CODE (intype) == REAL_TYPE)
666 && ! (convtype & CONV_STATIC))
667 || TREE_CODE (intype) == POINTER_TYPE)
669 if (flags & LOOKUP_COMPLAIN)
670 permerror (input_location, "conversion from %q#T to %q#T", intype, type);
672 if (!flag_permissive)
673 return error_mark_node;
676 /* [expr.static.cast]
678 8. A value of integral or enumeration type can be explicitly
679 converted to an enumeration type. The value is unchanged if
680 the original value is within the range of the enumeration
681 values. Otherwise, the resulting enumeration value is
683 if (TREE_CODE (expr) == INTEGER_CST && !int_fits_type_p (expr, type))
684 warning (OPT_Wconversion,
685 "the result of the conversion is unspecified because "
686 "%qE is outside the range of type %qT",
689 if (MAYBE_CLASS_TYPE_P (intype))
692 rval = build_type_conversion (type, e);
695 if (flags & LOOKUP_COMPLAIN)
696 error ("%q#T used where a %qT was expected", intype, type);
697 return error_mark_node;
699 if (code == BOOLEAN_TYPE)
700 return cp_truthvalue_conversion (e);
702 return fold_if_not_in_template (convert_to_integer (type, e));
704 if (POINTER_TYPE_P (type) || TYPE_PTR_TO_MEMBER_P (type))
705 return fold_if_not_in_template (cp_convert_to_pointer (type, e));
706 if (code == VECTOR_TYPE)
708 tree in_vtype = TREE_TYPE (e);
709 if (MAYBE_CLASS_TYPE_P (in_vtype))
712 ret_val = build_type_conversion (type, e);
715 if (flags & LOOKUP_COMPLAIN)
716 error ("%q#T used where a %qT was expected", in_vtype, type);
717 return error_mark_node;
719 return fold_if_not_in_template (convert_to_vector (type, e));
721 if (code == REAL_TYPE || code == COMPLEX_TYPE)
723 if (MAYBE_CLASS_TYPE_P (TREE_TYPE (e)))
726 rval = build_type_conversion (type, e);
730 if (flags & LOOKUP_COMPLAIN)
731 error ("%q#T used where a floating point value was expected",
734 if (code == REAL_TYPE)
735 return fold_if_not_in_template (convert_to_real (type, e));
736 else if (code == COMPLEX_TYPE)
737 return fold_if_not_in_template (convert_to_complex (type, e));
740 /* New C++ semantics: since assignment is now based on
741 memberwise copying, if the rhs type is derived from the
742 lhs type, then we may still do a conversion. */
743 if (RECORD_OR_UNION_CODE_P (code))
745 tree dtype = TREE_TYPE (e);
746 tree ctor = NULL_TREE;
748 dtype = TYPE_MAIN_VARIANT (dtype);
750 /* Conversion between aggregate types. New C++ semantics allow
751 objects of derived type to be cast to objects of base type.
752 Old semantics only allowed this between pointers.
754 There may be some ambiguity between using a constructor
755 vs. using a type conversion operator when both apply. */
759 if (abstract_virtuals_error (NULL_TREE, type))
760 return error_mark_node;
762 if (BRACE_ENCLOSED_INITIALIZER_P (ctor))
763 ctor = perform_implicit_conversion (type, ctor, tf_warning_or_error);
764 else if ((flags & LOOKUP_ONLYCONVERTING)
765 && ! (CLASS_TYPE_P (dtype) && DERIVED_FROM_P (type, dtype)))
766 /* For copy-initialization, first we create a temp of the proper type
767 with a user-defined conversion sequence, then we direct-initialize
768 the target with the temp (see [dcl.init]). */
769 ctor = build_user_type_conversion (type, ctor, flags);
772 VEC(tree,gc) *ctor_vec = make_tree_vector_single (ctor);
773 ctor = build_special_member_call (NULL_TREE,
774 complete_ctor_identifier,
777 tf_warning_or_error);
778 release_tree_vector (ctor_vec);
781 return build_cplus_new (type, ctor);
784 if (flags & LOOKUP_COMPLAIN)
786 /* If the conversion failed and expr was an invalid use of pointer to
787 member function, try to report a meaningful error. */
788 if (invalid_nonstatic_memfn_p (expr, tf_warning_or_error))
789 /* We displayed the error message. */;
791 error ("conversion from %qT to non-scalar type %qT requested",
792 TREE_TYPE (expr), type);
794 return error_mark_node;
797 /* When an expression is used in a void context, its value is discarded and
798 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
799 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
800 in a void context. The C++ standard does not define what an `access' to an
801 object is, but there is reason to believe that it is the lvalue to rvalue
802 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
803 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
804 indicates that volatile semantics should be the same between C and C++
805 where ever possible. C leaves it implementation defined as to what
806 constitutes an access to a volatile. So, we interpret `*vp' as a read of
807 the volatile object `vp' points to, unless that is an incomplete type. For
808 volatile references we do not do this interpretation, because that would
809 make it impossible to ignore the reference return value from functions. We
810 issue warnings in the confusing cases.
812 IMPLICIT is non-NULL iff an expression is being implicitly converted; it
813 is NULL when the user is explicitly converting an expression to void via
814 a cast. When non-NULL, IMPLICIT is a string indicating the context of
815 the implicit conversion. */
818 convert_to_void (tree expr, const char *implicit, tsubst_flags_t complain)
820 if (expr == error_mark_node
821 || TREE_TYPE (expr) == error_mark_node)
822 return error_mark_node;
823 if (!TREE_TYPE (expr))
825 if (invalid_nonstatic_memfn_p (expr, complain))
826 return error_mark_node;
827 if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR)
829 if (complain & tf_error)
830 error ("pseudo-destructor is not called");
831 return error_mark_node;
833 if (VOID_TYPE_P (TREE_TYPE (expr)))
835 switch (TREE_CODE (expr))
839 /* The two parts of a cond expr might be separate lvalues. */
840 tree op1 = TREE_OPERAND (expr,1);
841 tree op2 = TREE_OPERAND (expr,2);
842 bool side_effects = TREE_SIDE_EFFECTS (op1) || TREE_SIDE_EFFECTS (op2);
843 tree new_op1 = convert_to_void
844 (op1, (implicit && !side_effects
845 ? "second operand of conditional" : NULL), complain);
846 tree new_op2 = convert_to_void
847 (op2, (implicit && !side_effects
848 ? "third operand of conditional" : NULL), complain);
850 expr = build3 (COND_EXPR, TREE_TYPE (new_op1),
851 TREE_OPERAND (expr, 0), new_op1, new_op2);
857 /* The second part of a compound expr contains the value. */
858 tree op1 = TREE_OPERAND (expr,1);
859 tree new_op1 = convert_to_void
860 (op1, (implicit && !TREE_NO_WARNING (expr)
861 ? "right-hand operand of comma" : NULL), complain);
865 tree t = build2 (COMPOUND_EXPR, TREE_TYPE (new_op1),
866 TREE_OPERAND (expr, 0), new_op1);
873 case NON_LVALUE_EXPR:
875 /* These have already decayed to rvalue. */
878 case CALL_EXPR: /* We have a special meaning for volatile void fn(). */
883 tree type = TREE_TYPE (expr);
884 int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
886 int is_volatile = TYPE_VOLATILE (type);
887 int is_complete = COMPLETE_TYPE_P (complete_type (type));
889 /* Can't load the value if we don't know the type. */
890 if (is_volatile && !is_complete)
892 if (complain & tf_warning)
893 warning (0, "object of incomplete type %qT will not be accessed in %s",
894 type, implicit ? implicit : "void context");
896 /* Don't load the value if this is an implicit dereference, or if
897 the type needs to be handled by ctors/dtors. */
898 else if (is_volatile && (is_reference || TREE_ADDRESSABLE (type)))
900 if (complain & tf_warning)
901 warning (0, "object of type %qT will not be accessed in %s",
902 TREE_TYPE (TREE_OPERAND (expr, 0)),
903 implicit ? implicit : "void context");
905 if (is_reference || !is_volatile || !is_complete || TREE_ADDRESSABLE (type))
907 /* Emit a warning (if enabled) when the "effect-less" INDIRECT_REF
908 operation is stripped off. Note that we don't warn about
909 - an expression with TREE_NO_WARNING set. (For an example of
910 such expressions, see build_over_call in call.c.)
911 - automatic dereferencing of references, since the user cannot
912 control it. (See also warn_if_unused_value() in stmt.c.) */
913 if (warn_unused_value
915 && (complain & tf_warning)
916 && !TREE_NO_WARNING (expr)
918 warning (OPT_Wunused_value, "value computed is not used");
919 expr = TREE_OPERAND (expr, 0);
927 /* External variables might be incomplete. */
928 tree type = TREE_TYPE (expr);
929 int is_complete = COMPLETE_TYPE_P (complete_type (type));
931 if (TYPE_VOLATILE (type) && !is_complete && (complain & tf_warning))
932 warning (0, "object %qE of incomplete type %qT will not be accessed in %s",
933 expr, type, implicit ? implicit : "void context");
938 /* Don't bother with the temporary object returned from a function if
939 we don't use it and don't need to destroy it. We'll still
940 allocate space for it in expand_call or declare_return_variable,
941 but we don't need to track it through all the tree phases. */
942 if (TARGET_EXPR_IMPLICIT_P (expr)
943 && TYPE_HAS_TRIVIAL_DESTRUCTOR (TREE_TYPE (expr)))
945 tree init = TARGET_EXPR_INITIAL (expr);
946 if (TREE_CODE (init) == AGGR_INIT_EXPR
947 && !AGGR_INIT_VIA_CTOR_P (init))
949 tree fn = AGGR_INIT_EXPR_FN (init);
950 expr = build_call_array_loc (input_location,
951 TREE_TYPE (TREE_TYPE (TREE_TYPE (fn))),
953 aggr_init_expr_nargs (init),
954 AGGR_INIT_EXPR_ARGP (init));
961 expr = resolve_nondeduced_context (expr);
965 if (TREE_CODE (probe) == ADDR_EXPR)
966 probe = TREE_OPERAND (expr, 0);
967 if (type_unknown_p (probe))
969 /* [over.over] enumerates the places where we can take the address
970 of an overloaded function, and this is not one of them. */
971 if (complain & tf_error)
972 error ("%s cannot resolve address of overloaded function",
973 implicit ? implicit : "void cast");
975 return error_mark_node;
976 expr = void_zero_node;
978 else if (implicit && probe == expr && is_overloaded_fn (probe))
980 /* Only warn when there is no &. */
981 if (complain & tf_warning)
982 warning (OPT_Waddress, "%s is a reference, not call, to function %qE",
984 if (TREE_CODE (expr) == COMPONENT_REF)
985 expr = TREE_OPERAND (expr, 0);
989 if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
993 && !TREE_NO_WARNING (expr)
994 && !processing_template_decl)
996 /* The middle end does not warn about expressions that have
997 been explicitly cast to void, so we must do so here. */
998 if (!TREE_SIDE_EFFECTS (expr)) {
999 if (complain & tf_warning)
1000 warning (OPT_Wunused_value, "%s has no effect", implicit);
1005 enum tree_code code;
1006 enum tree_code_class tclass;
1009 /* We might like to warn about (say) "(int) f()", as the
1010 cast has no effect, but the compiler itself will
1011 generate implicit conversions under some
1012 circumstances. (For example a block copy will be
1013 turned into a call to "__builtin_memcpy", with a
1014 conversion of the return value to an appropriate
1015 type.) So, to avoid false positives, we strip
1016 conversions. Do not use STRIP_NOPs because it will
1017 not strip conversions to "void", as that is not a
1018 mode-preserving conversion. */
1019 while (TREE_CODE (e) == NOP_EXPR)
1020 e = TREE_OPERAND (e, 0);
1022 code = TREE_CODE (e);
1023 tclass = TREE_CODE_CLASS (code);
1024 if ((tclass == tcc_comparison
1025 || tclass == tcc_unary
1026 || (tclass == tcc_binary
1027 && !(code == MODIFY_EXPR
1028 || code == INIT_EXPR
1029 || code == PREDECREMENT_EXPR
1030 || code == PREINCREMENT_EXPR
1031 || code == POSTDECREMENT_EXPR
1032 || code == POSTINCREMENT_EXPR)))
1033 && (complain & tf_warning))
1034 warning (OPT_Wunused_value, "value computed is not used");
1037 expr = build1 (CONVERT_EXPR, void_type_node, expr);
1039 if (! TREE_SIDE_EFFECTS (expr))
1040 expr = void_zero_node;
1044 /* Create an expression whose value is that of EXPR,
1045 converted to type TYPE. The TREE_TYPE of the value
1046 is always TYPE. This function implements all reasonable
1047 conversions; callers should filter out those that are
1048 not permitted by the language being compiled.
1050 Most of this routine is from build_reinterpret_cast.
1052 The back end cannot call cp_convert (what was convert) because
1053 conversions to/from basetypes may involve memory references
1054 (vbases) and adding or subtracting small values (multiple
1055 inheritance), but it calls convert from the constant folding code
1056 on subtrees of already built trees after it has ripped them apart.
1058 Also, if we ever support range variables, we'll probably also have to
1059 do a little bit more work. */
1062 convert (tree type, tree expr)
1066 if (type == error_mark_node || expr == error_mark_node)
1067 return error_mark_node;
1069 intype = TREE_TYPE (expr);
1071 if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype))
1072 return fold_if_not_in_template (build_nop (type, expr));
1074 return ocp_convert (type, expr, CONV_OLD_CONVERT,
1075 LOOKUP_NORMAL|LOOKUP_NO_CONVERSION);
1078 /* Like cp_convert, except permit conversions to take place which
1079 are not normally allowed due to access restrictions
1080 (such as conversion from sub-type to private super-type). */
1083 convert_force (tree type, tree expr, int convtype)
1086 enum tree_code code = TREE_CODE (type);
1088 if (code == REFERENCE_TYPE)
1089 return (fold_if_not_in_template
1090 (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN,
1093 if (code == POINTER_TYPE)
1094 return fold_if_not_in_template (convert_to_pointer_force (type, e));
1096 /* From typeck.c convert_for_assignment */
1097 if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR
1098 && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE
1099 && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE)
1100 || integer_zerop (e)
1101 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e)))
1102 && TYPE_PTRMEMFUNC_P (type))
1103 /* compatible pointer to member functions. */
1104 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1,
1107 return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL);
1110 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1111 exists, return the attempted conversion. This may
1112 return ERROR_MARK_NODE if the conversion is not
1113 allowed (references private members, etc).
1114 If no conversion exists, NULL_TREE is returned.
1116 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1117 object parameter, or by the second standard conversion sequence if
1118 that doesn't do it. This will probably wait for an overloading rewrite.
1122 build_type_conversion (tree xtype, tree expr)
1124 /* C++: check to see if we can convert this aggregate type
1125 into the required type. */
1126 return build_user_type_conversion (xtype, expr, LOOKUP_NORMAL);
1129 /* Convert the given EXPR to one of a group of types suitable for use in an
1130 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1131 which indicates which types are suitable. If COMPLAIN is true, complain
1132 about ambiguity; otherwise, the caller will deal with it. */
1135 build_expr_type_conversion (int desires, tree expr, bool complain)
1137 tree basetype = TREE_TYPE (expr);
1138 tree conv = NULL_TREE;
1139 tree winner = NULL_TREE;
1141 if (expr == null_node
1142 && (desires & WANT_INT)
1143 && !(desires & WANT_NULL))
1144 warning_at (input_location, OPT_Wconversion_null,
1145 "converting NULL to non-pointer type");
1147 basetype = TREE_TYPE (expr);
1149 if (basetype == error_mark_node)
1150 return error_mark_node;
1152 if (! MAYBE_CLASS_TYPE_P (basetype))
1153 switch (TREE_CODE (basetype))
1156 if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
1158 /* else fall through... */
1161 return (desires & WANT_INT) ? expr : NULL_TREE;
1163 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1165 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1167 return (desires & WANT_POINTER) ? expr : NULL_TREE;
1171 return (desires & WANT_POINTER) ? decay_conversion (expr)
1176 if ((desires & WANT_VECTOR_OR_COMPLEX) == 0)
1178 switch (TREE_CODE (TREE_TYPE (basetype)))
1182 return (desires & WANT_INT) ? expr : NULL_TREE;
1184 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1186 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1195 /* The code for conversions from class type is currently only used for
1196 delete expressions. Other expressions are handled by build_new_op. */
1197 if (!complete_type_or_else (basetype, expr))
1198 return error_mark_node;
1199 if (!TYPE_HAS_CONVERSION (basetype))
1202 for (conv = lookup_conversions (basetype, /*lookup_template_convs_p=*/true);
1204 conv = TREE_CHAIN (conv))
1208 tree cand = TREE_VALUE (conv);
1209 cand = OVL_CURRENT (cand);
1211 if (winner && winner == cand)
1214 if (DECL_NONCONVERTING_P (cand))
1217 candidate = non_reference (TREE_TYPE (TREE_TYPE (cand)));
1219 switch (TREE_CODE (candidate))
1223 win = (desires & WANT_INT); break;
1225 win = (desires & WANT_ENUM); break;
1227 win = (desires & WANT_FLOAT); break;
1229 win = (desires & WANT_POINTER); break;
1233 if ((desires & WANT_VECTOR_OR_COMPLEX) == 0)
1235 switch (TREE_CODE (TREE_TYPE (candidate)))
1239 win = (desires & WANT_INT); break;
1241 win = (desires & WANT_ENUM); break;
1243 win = (desires & WANT_FLOAT); break;
1259 error ("ambiguous default type conversion from %qT",
1261 error (" candidate conversions include %qD and %qD",
1264 return error_mark_node;
1273 tree type = non_reference (TREE_TYPE (TREE_TYPE (winner)));
1274 return build_user_type_conversion (type, expr, LOOKUP_NORMAL);
1280 /* Implements integral promotion (4.1) and float->double promotion. */
1283 type_promotes_to (tree type)
1287 if (type == error_mark_node)
1288 return error_mark_node;
1290 type = TYPE_MAIN_VARIANT (type);
1292 /* Check for promotions of target-defined types first. */
1293 promoted_type = targetm.promoted_type (type);
1295 return promoted_type;
1297 /* bool always promotes to int (not unsigned), even if it's the same
1299 if (TREE_CODE (type) == BOOLEAN_TYPE)
1300 type = integer_type_node;
1302 /* Normally convert enums to int, but convert wide enums to something
1304 else if (TREE_CODE (type) == ENUMERAL_TYPE
1305 || type == char16_type_node
1306 || type == char32_type_node
1307 || type == wchar_type_node)
1309 int precision = MAX (TYPE_PRECISION (type),
1310 TYPE_PRECISION (integer_type_node));
1311 tree totype = c_common_type_for_size (precision, 0);
1312 if (TYPE_UNSIGNED (type)
1313 && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype))
1314 type = c_common_type_for_size (precision, 1);
1318 else if (c_promoting_integer_type_p (type))
1320 /* Retain unsignedness if really not getting bigger. */
1321 if (TYPE_UNSIGNED (type)
1322 && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
1323 type = unsigned_type_node;
1325 type = integer_type_node;
1327 else if (type == float_type_node)
1328 type = double_type_node;
1333 /* The routines below this point are carefully written to conform to
1334 the standard. They use the same terminology, and follow the rules
1335 closely. Although they are used only in pt.c at the moment, they
1336 should presumably be used everywhere in the future. */
1338 /* Attempt to perform qualification conversions on EXPR to convert it
1339 to TYPE. Return the resulting expression, or error_mark_node if
1340 the conversion was impossible. */
1343 perform_qualification_conversions (tree type, tree expr)
1347 expr_type = TREE_TYPE (expr);
1349 if (same_type_p (type, expr_type))
1351 else if (TYPE_PTR_P (type) && TYPE_PTR_P (expr_type)
1352 && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (expr_type)))
1353 return build_nop (type, expr);
1354 else if (TYPE_PTR_TO_MEMBER_P (type)
1355 && TYPE_PTR_TO_MEMBER_P (expr_type)
1356 && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type),
1357 TYPE_PTRMEM_CLASS_TYPE (expr_type))
1358 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type),
1359 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type)))
1360 return build_nop (type, expr);
1362 return error_mark_node;