1 /* Language-level data type conversion for GNU C++.
2 Copyright (C) 1987-2016 Free Software Foundation, Inc.
3 Hacked by Michael Tiemann (tiemann@cygnus.com)
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
22 /* This file contains the functions for converting C++ expressions
23 to different data types. The only entry point is `convert'.
24 Every language front end must have a `convert' function
25 but what kind of conversions it does will depend on the language. */
29 #include "coretypes.h"
32 #include "stor-layout.h"
37 static tree
convert_to_pointer_force (tree
, tree
, tsubst_flags_t
);
38 static tree
build_type_conversion (tree
, tree
);
39 static tree
build_up_reference (tree
, tree
, int, tree
, tsubst_flags_t
);
40 static void diagnose_ref_binding (location_t
, tree
, tree
, tree
);
42 /* Change of width--truncation and extension of integers or reals--
43 is represented with NOP_EXPR. Proper functioning of many things
44 assumes that no other conversions can be NOP_EXPRs.
46 Conversion between integer and pointer is represented with CONVERT_EXPR.
47 Converting integer to real uses FLOAT_EXPR
48 and real to integer uses FIX_TRUNC_EXPR.
50 Here is a list of all the functions that assume that widening and
51 narrowing is always done with a NOP_EXPR:
52 In convert.c, convert_to_integer[_maybe_fold].
53 In c-typeck.c, build_binary_op_nodefault (boolean ops),
54 and c_common_truthvalue_conversion.
55 In expr.c: expand_expr, for operands of a MULT_EXPR.
56 In fold-const.c: fold.
57 In tree.c: get_narrower and get_unwidened.
59 C++: in multiple-inheritance, converting between pointers may involve
60 adjusting them by a delta stored within the class definition. */
62 /* Subroutines of `convert'. */
64 /* if converting pointer to pointer
65 if dealing with classes, check for derived->base or vice versa
66 else if dealing with method pointers, delegate
68 else if converting class, pass off to build_type_conversion
69 else try C-style pointer conversion. */
72 cp_convert_to_pointer (tree type
, tree expr
, bool dofold
,
73 tsubst_flags_t complain
)
75 tree intype
= TREE_TYPE (expr
);
78 location_t loc
= EXPR_LOC_OR_LOC (expr
, input_location
);
80 if (intype
== error_mark_node
)
81 return error_mark_node
;
83 if (MAYBE_CLASS_TYPE_P (intype
))
85 intype
= complete_type (intype
);
86 if (!COMPLETE_TYPE_P (intype
))
88 if (complain
& tf_error
)
89 error_at (loc
, "can%'t convert from incomplete type %qT to %qT",
91 return error_mark_node
;
94 rval
= build_type_conversion (type
, expr
);
97 if ((complain
& tf_error
)
98 && rval
== error_mark_node
)
99 error_at (loc
, "conversion of %qE from %qT to %qT is ambiguous",
105 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
106 if (TYPE_PTR_P (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
, complain
);
113 if (TYPE_PTR_P (TREE_TYPE (expr
)))
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
129 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
130 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type
))
131 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype
))
132 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
134 enum tree_code code
= PLUS_EXPR
;
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
));
146 /* Try derived to base conversion. */
148 binfo
= lookup_base (intype_class
, type_class
, ba_check
,
150 if (!same_p
&& !binfo
)
152 /* Try base to derived conversion. */
153 binfo
= lookup_base (type_class
, intype_class
, ba_check
,
157 if (binfo
== error_mark_node
)
158 return error_mark_node
;
162 expr
= build_base_path (code
, expr
, binfo
, 0, complain
);
163 /* Add any qualifier conversions. */
164 return build_nop (type
, expr
);
168 if (TYPE_PTRMEMFUNC_P (type
))
170 if (complain
& tf_error
)
171 error_at (loc
, "cannot convert %qE from type %qT to type %qT",
173 return error_mark_node
;
176 return build_nop (type
, expr
);
178 else if ((TYPE_PTRDATAMEM_P (type
) && TYPE_PTRDATAMEM_P (intype
))
179 || (TYPE_PTRMEMFUNC_P (type
) && TYPE_PTRMEMFUNC_P (intype
)))
180 return convert_ptrmem (type
, expr
, /*allow_inverse_p=*/false,
181 /*c_cast_p=*/false, complain
);
182 else if (TYPE_PTRMEMFUNC_P (intype
))
186 if (TREE_CODE (expr
) == PTRMEM_CST
)
187 return cp_convert_to_pointer (type
, PTRMEM_CST_MEMBER (expr
),
189 else if (TREE_CODE (expr
) == OFFSET_REF
)
191 tree object
= TREE_OPERAND (expr
, 0);
192 return get_member_function_from_ptrfunc (&object
,
193 TREE_OPERAND (expr
, 1),
197 if (complain
& tf_error
)
198 error_at (loc
, "cannot convert %qE from type %qT to type %qT",
200 return error_mark_node
;
203 if (null_ptr_cst_p (expr
))
205 if (TYPE_PTRMEMFUNC_P (type
))
206 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), expr
, 0,
207 /*c_cast_p=*/false, complain
);
209 if (complain
& tf_warning
)
210 maybe_warn_zero_as_null_pointer_constant (expr
, loc
);
212 /* A NULL pointer-to-data-member is represented by -1, not by
214 tree val
= (TYPE_PTRDATAMEM_P (type
)
215 ? build_int_cst_type (type
, -1)
216 : build_int_cst (type
, 0));
218 return (TREE_SIDE_EFFECTS (expr
)
219 ? build2 (COMPOUND_EXPR
, type
, expr
, val
) : val
);
221 else if (TYPE_PTRMEM_P (type
) && INTEGRAL_CODE_P (form
))
223 if (complain
& tf_error
)
224 error_at (loc
, "invalid conversion from %qT to %qT", intype
, type
);
225 return error_mark_node
;
228 if (INTEGRAL_CODE_P (form
))
230 if (TYPE_PRECISION (intype
) == POINTER_SIZE
)
231 return build1 (CONVERT_EXPR
, type
, expr
);
232 expr
= cp_convert (c_common_type_for_size (POINTER_SIZE
, 0), expr
,
234 /* Modes may be different but sizes should be the same. There
235 is supposed to be some integral type that is the same width
237 gcc_assert (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr
)))
238 == GET_MODE_SIZE (TYPE_MODE (type
)));
240 return convert_to_pointer_maybe_fold (type
, expr
, dofold
);
243 if (type_unknown_p (expr
))
244 return instantiate_type (type
, expr
, complain
);
246 if (complain
& tf_error
)
247 error_at (loc
, "cannot convert %qE from type %qT to type %qT",
249 return error_mark_node
;
252 /* Like convert, except permit conversions to take place which
253 are not normally allowed due to access restrictions
254 (such as conversion from sub-type to private super-type). */
257 convert_to_pointer_force (tree type
, tree expr
, tsubst_flags_t complain
)
259 tree intype
= TREE_TYPE (expr
);
260 enum tree_code form
= TREE_CODE (intype
);
262 if (form
== POINTER_TYPE
)
264 intype
= TYPE_MAIN_VARIANT (intype
);
266 if (TYPE_MAIN_VARIANT (type
) != intype
267 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
268 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type
))
269 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype
))
270 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
272 enum tree_code code
= PLUS_EXPR
;
275 binfo
= lookup_base (TREE_TYPE (intype
), TREE_TYPE (type
),
276 ba_unique
, NULL
, complain
);
279 binfo
= lookup_base (TREE_TYPE (type
), TREE_TYPE (intype
),
280 ba_unique
, NULL
, complain
);
283 if (binfo
== error_mark_node
)
284 return error_mark_node
;
287 expr
= build_base_path (code
, expr
, binfo
, 0, complain
);
288 if (expr
== error_mark_node
)
289 return error_mark_node
;
290 /* Add any qualifier conversions. */
291 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr
)),
293 expr
= build_nop (type
, expr
);
299 return cp_convert_to_pointer (type
, expr
, /*fold*/false, complain
);
302 /* We are passing something to a function which requires a reference.
303 The type we are interested in is in TYPE. The initial
304 value we have to begin with is in ARG.
306 FLAGS controls how we manage access checking.
307 DIRECT_BIND in FLAGS controls how any temporaries are generated.
308 If DIRECT_BIND is set, DECL is the reference we're binding to. */
311 build_up_reference (tree type
, tree arg
, int flags
, tree decl
,
312 tsubst_flags_t complain
)
315 tree argtype
= TREE_TYPE (arg
);
316 tree target_type
= TREE_TYPE (type
);
318 gcc_assert (TREE_CODE (type
) == REFERENCE_TYPE
);
320 if ((flags
& DIRECT_BIND
) && ! lvalue_p (arg
))
322 /* Create a new temporary variable. We can't just use a TARGET_EXPR
323 here because it needs to live as long as DECL. */
326 arg
= make_temporary_var_for_ref_to_temp (decl
, target_type
);
328 /* Process the initializer for the declaration. */
329 DECL_INITIAL (arg
) = targ
;
330 cp_finish_decl (arg
, targ
, /*init_const_expr_p=*/false, NULL_TREE
,
331 LOOKUP_ONLYCONVERTING
|DIRECT_BIND
);
333 else if (!(flags
& DIRECT_BIND
) && ! obvalue_p (arg
))
334 return get_target_expr_sfinae (arg
, complain
);
336 /* If we had a way to wrap this up, and say, if we ever needed its
337 address, transform all occurrences of the register, into a memory
338 reference we could win better. */
339 rval
= cp_build_addr_expr (arg
, complain
);
340 if (rval
== error_mark_node
)
341 return error_mark_node
;
343 if ((flags
& LOOKUP_PROTECT
)
344 && TYPE_MAIN_VARIANT (argtype
) != TYPE_MAIN_VARIANT (target_type
)
345 && MAYBE_CLASS_TYPE_P (argtype
)
346 && MAYBE_CLASS_TYPE_P (target_type
))
348 /* We go through lookup_base for the access control. */
349 tree binfo
= lookup_base (argtype
, target_type
, ba_check
,
351 if (binfo
== error_mark_node
)
352 return error_mark_node
;
353 if (binfo
== NULL_TREE
)
354 return error_not_base_type (target_type
, argtype
);
355 rval
= build_base_path (PLUS_EXPR
, rval
, binfo
, 1, complain
);
359 = convert_to_pointer_force (build_pointer_type (target_type
),
361 return build_nop (type
, rval
);
364 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
365 INTYPE is the original rvalue type and DECL is an optional _DECL node
368 [dcl.init.ref] says that if an rvalue is used to
369 initialize a reference, then the reference must be to a
370 non-volatile const type. */
373 diagnose_ref_binding (location_t loc
, tree reftype
, tree intype
, tree decl
)
375 tree ttl
= TREE_TYPE (reftype
);
377 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl
))
381 if (CP_TYPE_VOLATILE_P (ttl
) && decl
)
382 msg
= G_("initialization of volatile reference type %q#T from "
383 "rvalue of type %qT");
384 else if (CP_TYPE_VOLATILE_P (ttl
))
385 msg
= G_("conversion to volatile reference type %q#T "
386 "from rvalue of type %qT");
388 msg
= G_("initialization of non-const reference type %q#T from "
389 "rvalue of type %qT");
391 msg
= G_("conversion to non-const reference type %q#T from "
392 "rvalue of type %qT");
394 permerror (loc
, msg
, reftype
, intype
);
398 /* For C++: Only need to do one-level references, but cannot
399 get tripped up on signed/unsigned differences.
401 DECL is either NULL_TREE or the _DECL node for a reference that is being
402 initialized. It can be error_mark_node if we don't know the _DECL but
403 we know it's an initialization. */
406 convert_to_reference (tree reftype
, tree expr
, int convtype
,
407 int flags
, tree decl
, tsubst_flags_t complain
)
409 tree type
= TYPE_MAIN_VARIANT (TREE_TYPE (reftype
));
411 tree rval
= NULL_TREE
;
412 tree rval_as_conversion
= NULL_TREE
;
413 bool can_convert_intype_to_type
;
414 location_t loc
= EXPR_LOC_OR_LOC (expr
, input_location
);
416 if (TREE_CODE (type
) == FUNCTION_TYPE
417 && TREE_TYPE (expr
) == unknown_type_node
)
418 expr
= instantiate_type (type
, expr
, complain
);
420 if (expr
== error_mark_node
)
421 return error_mark_node
;
423 intype
= TREE_TYPE (expr
);
425 gcc_assert (TREE_CODE (intype
) != REFERENCE_TYPE
);
426 gcc_assert (TREE_CODE (reftype
) == REFERENCE_TYPE
);
428 intype
= TYPE_MAIN_VARIANT (intype
);
430 can_convert_intype_to_type
= can_convert_standard (type
, intype
, complain
);
432 if (!can_convert_intype_to_type
433 && (convtype
& CONV_IMPLICIT
) && MAYBE_CLASS_TYPE_P (intype
)
434 && ! (flags
& LOOKUP_NO_CONVERSION
))
436 /* Look for a user-defined conversion to lvalue that we can use. */
439 = build_type_conversion (reftype
, expr
);
441 if (rval_as_conversion
&& rval_as_conversion
!= error_mark_node
442 && lvalue_p (rval_as_conversion
))
444 expr
= rval_as_conversion
;
445 rval_as_conversion
= NULL_TREE
;
447 can_convert_intype_to_type
= 1;
451 if (((convtype
& CONV_STATIC
)
452 && can_convert_standard (intype
, type
, complain
))
453 || ((convtype
& CONV_IMPLICIT
) && can_convert_intype_to_type
))
456 tree ttl
= TREE_TYPE (reftype
);
457 tree ttr
= lvalue_type (expr
);
459 if ((complain
& tf_error
)
460 && ! lvalue_p (expr
))
461 diagnose_ref_binding (loc
, reftype
, intype
, decl
);
463 if (! (convtype
& CONV_CONST
)
464 && !at_least_as_qualified_p (ttl
, ttr
))
466 if (complain
& tf_error
)
467 permerror (loc
, "conversion from %qT to %qT discards qualifiers",
470 return error_mark_node
;
474 return build_up_reference (reftype
, expr
, flags
, decl
, complain
);
476 else if ((convtype
& CONV_REINTERPRET
) && obvalue_p (expr
))
478 /* When casting an lvalue to a reference type, just convert into
479 a pointer to the new type and deference it. This is allowed
480 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
481 should be done directly (jason). (int &)ri ---> *(int*)&ri */
483 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
485 if ((complain
& tf_warning
)
486 && TYPE_PTR_P (intype
)
487 && (comptypes (TREE_TYPE (intype
), type
,
488 COMPARE_BASE
| COMPARE_DERIVED
)))
489 warning_at (loc
, 0, "casting %qT to %qT does not dereference pointer",
492 rval
= cp_build_addr_expr (expr
, complain
);
493 if (rval
!= error_mark_node
)
494 rval
= convert_force (build_pointer_type (TREE_TYPE (reftype
)),
496 if (rval
!= error_mark_node
)
497 rval
= build1 (NOP_EXPR
, reftype
, rval
);
501 rval
= convert_for_initialization (NULL_TREE
, type
, expr
, flags
,
502 ICR_CONVERTING
, 0, 0, complain
);
503 if (rval
== NULL_TREE
|| rval
== error_mark_node
)
505 if (complain
& tf_error
)
506 diagnose_ref_binding (loc
, reftype
, intype
, decl
);
507 rval
= build_up_reference (reftype
, rval
, flags
, decl
, complain
);
512 /* If we found a way to convert earlier, then use it. */
516 if (complain
& tf_error
)
517 error_at (loc
, "cannot convert type %qT to type %qT", intype
, reftype
);
519 return error_mark_node
;
522 /* We are using a reference VAL for its value. Bash that reference all the
523 way down to its lowest form. */
526 convert_from_reference (tree val
)
529 && TREE_CODE (TREE_TYPE (val
)) == REFERENCE_TYPE
)
531 tree t
= TREE_TYPE (TREE_TYPE (val
));
532 tree ref
= build1 (INDIRECT_REF
, t
, val
);
535 /* We *must* set TREE_READONLY when dereferencing a pointer to const,
536 so that we get the proper error message if the result is used
537 to assign to. Also, &* is supposed to be a no-op. */
538 TREE_READONLY (ref
) = CP_TYPE_CONST_P (t
);
539 TREE_THIS_VOLATILE (ref
) = CP_TYPE_VOLATILE_P (t
);
540 TREE_SIDE_EFFECTS (ref
)
541 = (TREE_THIS_VOLATILE (ref
) || TREE_SIDE_EFFECTS (val
));
548 /* Really perform an lvalue-to-rvalue conversion, including copying an
549 argument of class type into a temporary. */
552 force_rvalue (tree expr
, tsubst_flags_t complain
)
554 tree type
= TREE_TYPE (expr
);
555 if (MAYBE_CLASS_TYPE_P (type
) && TREE_CODE (expr
) != TARGET_EXPR
)
557 vec
<tree
, va_gc
> *args
= make_tree_vector_single (expr
);
558 expr
= build_special_member_call (NULL_TREE
, complete_ctor_identifier
,
559 &args
, type
, LOOKUP_NORMAL
, complain
);
560 release_tree_vector (args
);
561 expr
= build_cplus_new (type
, expr
, complain
);
564 expr
= decay_conversion (expr
, complain
);
570 /* If EXPR and ORIG are INTEGER_CSTs, return a version of EXPR that has
571 TREE_OVERFLOW set only if it is set in ORIG. Otherwise, return EXPR
575 ignore_overflows (tree expr
, tree orig
)
577 if (TREE_CODE (expr
) == INTEGER_CST
578 && TREE_CODE (orig
) == INTEGER_CST
579 && TREE_OVERFLOW (expr
) != TREE_OVERFLOW (orig
))
581 gcc_assert (!TREE_OVERFLOW (orig
));
582 /* Ensure constant sharing. */
583 expr
= wide_int_to_tree (TREE_TYPE (expr
), expr
);
588 /* Fold away simple conversions, but make sure TREE_OVERFLOW is set
592 cp_fold_convert (tree type
, tree expr
)
595 if (TREE_TYPE (expr
) == type
)
597 else if (TREE_CODE (expr
) == PTRMEM_CST
)
599 /* Avoid wrapping a PTRMEM_CST in NOP_EXPR. */
600 conv
= copy_node (expr
);
601 TREE_TYPE (conv
) = type
;
605 conv
= fold_convert (type
, expr
);
606 conv
= ignore_overflows (conv
, expr
);
611 /* C++ conversions, preference to static cast conversions. */
614 cp_convert (tree type
, tree expr
, tsubst_flags_t complain
)
616 return ocp_convert (type
, expr
, CONV_OLD_CONVERT
, LOOKUP_NORMAL
, complain
);
619 /* C++ equivalent of convert_and_check but using cp_convert as the
622 Convert EXPR to TYPE, warning about conversion problems with constants.
623 Invoke this function on every expression that is converted implicitly,
624 i.e. because of language rules and not because of an explicit cast. */
627 cp_convert_and_check (tree type
, tree expr
, tsubst_flags_t complain
)
631 if (TREE_TYPE (expr
) == type
)
633 if (expr
== error_mark_node
)
635 result
= cp_convert (type
, expr
, complain
);
637 if ((complain
& tf_warning
)
638 && c_inhibit_evaluation_warnings
== 0)
640 tree folded
= cp_fully_fold (expr
);
643 folded_result
= result
;
646 /* Avoid bogus -Wparentheses warnings. */
647 warning_sentinel
w (warn_parentheses
);
648 warning_sentinel
c (warn_int_in_bool_context
);
649 folded_result
= cp_convert (type
, folded
, tf_none
);
651 folded_result
= fold_simple (folded_result
);
652 if (!TREE_OVERFLOW_P (folded
)
653 && folded_result
!= error_mark_node
)
654 warnings_for_convert_and_check (EXPR_LOC_OR_LOC (expr
, input_location
),
655 type
, folded
, folded_result
);
661 /* Returns true if we should avoid even doing overload resolution for copying
662 EXPR to initialize a TYPE. */
665 early_elide_copy (tree type
, tree expr
)
667 if (TREE_CODE (expr
) != TARGET_EXPR
)
669 /* List-initialization and direct-initialization don't involve a copy. */
670 if (TARGET_EXPR_LIST_INIT_P (expr
)
671 || TARGET_EXPR_DIRECT_INIT_P (expr
))
673 /* In C++17, "If the initializer expression is a prvalue and the
674 cv-unqualified version of the source type is the same class as the class
675 of the destination, the initializer expression is used to initialize the
676 destination object." */
677 return (cxx_dialect
>= cxx1z
678 && (same_type_ignoring_top_level_qualifiers_p
679 (type
, TREE_TYPE (expr
))));
684 FLAGS indicates how we should behave. */
687 ocp_convert (tree type
, tree expr
, int convtype
, int flags
,
688 tsubst_flags_t complain
)
691 enum tree_code code
= TREE_CODE (type
);
692 const char *invalid_conv_diag
;
694 location_t loc
= EXPR_LOC_OR_LOC (expr
, input_location
);
695 bool dofold
= (convtype
& CONV_FOLD
);
697 if (error_operand_p (e
) || type
== error_mark_node
)
698 return error_mark_node
;
700 complete_type (type
);
701 complete_type (TREE_TYPE (expr
));
703 if ((invalid_conv_diag
704 = targetm
.invalid_conversion (TREE_TYPE (expr
), type
)))
706 if (complain
& tf_error
)
707 error (invalid_conv_diag
);
708 return error_mark_node
;
711 /* FIXME remove when moving to c_fully_fold model. */
712 if (!CLASS_TYPE_P (type
))
713 e
= scalar_constant_value (e
);
714 if (error_operand_p (e
))
715 return error_mark_node
;
717 if (MAYBE_CLASS_TYPE_P (type
) && (convtype
& CONV_FORCE_TEMP
)
718 && !early_elide_copy (type
, e
))
719 /* We need a new temporary; don't take this shortcut. */;
720 else if (same_type_ignoring_top_level_qualifiers_p (type
, TREE_TYPE (e
)))
722 if (same_type_p (type
, TREE_TYPE (e
)))
723 /* The call to fold will not always remove the NOP_EXPR as
724 might be expected, since if one of the types is a typedef;
725 the comparison in fold is just equality of pointers, not a
726 call to comptypes. We don't call fold in this case because
727 that can result in infinite recursion; fold will call
728 convert, which will call ocp_convert, etc. */
730 /* For complex data types, we need to perform componentwise
732 else if (TREE_CODE (type
) == COMPLEX_TYPE
)
733 return convert_to_complex_maybe_fold (type
, e
, dofold
);
734 else if (VECTOR_TYPE_P (type
))
735 return convert_to_vector (type
, e
);
736 else if (TREE_CODE (e
) == TARGET_EXPR
)
738 /* Don't build a NOP_EXPR of class type. Instead, change the
739 type of the temporary. */
740 TREE_TYPE (e
) = TREE_TYPE (TARGET_EXPR_SLOT (e
)) = type
;
745 /* We shouldn't be treating objects of ADDRESSABLE type as
747 gcc_assert (!TREE_ADDRESSABLE (type
));
748 return build_nop (type
, e
);
752 e1
= targetm
.convert_to_type (type
, e
);
756 if (code
== VOID_TYPE
&& (convtype
& CONV_STATIC
))
758 e
= convert_to_void (e
, ICV_CAST
, complain
);
762 if (INTEGRAL_CODE_P (code
))
764 tree intype
= TREE_TYPE (e
);
767 if (TREE_CODE (type
) == ENUMERAL_TYPE
)
769 /* enum = enum, enum = int, enum = float, (enum)pointer are all
771 if (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype
)
772 || TREE_CODE (intype
) == REAL_TYPE
)
773 && ! (convtype
& CONV_STATIC
))
774 || TYPE_PTR_P (intype
))
776 if (complain
& tf_error
)
777 permerror (loc
, "conversion from %q#T to %q#T", intype
, type
);
779 return error_mark_node
;
782 /* [expr.static.cast]
784 8. A value of integral or enumeration type can be explicitly
785 converted to an enumeration type. The value is unchanged if
786 the original value is within the range of the enumeration
787 values. Otherwise, the resulting enumeration value is
789 if ((complain
& tf_warning
)
790 && TREE_CODE (e
) == INTEGER_CST
791 && ENUM_UNDERLYING_TYPE (type
)
792 && !int_fits_type_p (e
, ENUM_UNDERLYING_TYPE (type
)))
793 warning_at (loc
, OPT_Wconversion
,
794 "the result of the conversion is unspecified because "
795 "%qE is outside the range of type %qT",
798 if (MAYBE_CLASS_TYPE_P (intype
))
801 rval
= build_type_conversion (type
, e
);
804 if (complain
& tf_error
)
805 error_at (loc
, "%q#T used where a %qT was expected", intype
, type
);
806 return error_mark_node
;
808 if (code
== BOOLEAN_TYPE
)
810 if (VOID_TYPE_P (intype
))
812 if (complain
& tf_error
)
814 "could not convert %qE from %<void%> to %<bool%>",
816 return error_mark_node
;
819 /* We can't implicitly convert a scoped enum to bool, so convert
820 to the underlying type first. */
821 if (SCOPED_ENUM_P (intype
) && (convtype
& CONV_STATIC
))
822 e
= build_nop (ENUM_UNDERLYING_TYPE (intype
), e
);
823 return cp_truthvalue_conversion (e
);
826 converted
= convert_to_integer_maybe_fold (type
, e
, dofold
);
828 /* Ignore any integer overflow caused by the conversion. */
829 return ignore_overflows (converted
, e
);
831 if (NULLPTR_TYPE_P (type
) && e
&& null_ptr_cst_p (e
))
833 if (complain
& tf_warning
)
834 maybe_warn_zero_as_null_pointer_constant (e
, loc
);
837 if (POINTER_TYPE_P (type
) || TYPE_PTRMEM_P (type
))
838 return cp_convert_to_pointer (type
, e
, dofold
, complain
);
839 if (code
== VECTOR_TYPE
)
841 tree in_vtype
= TREE_TYPE (e
);
842 if (MAYBE_CLASS_TYPE_P (in_vtype
))
845 ret_val
= build_type_conversion (type
, e
);
848 if (complain
& tf_error
)
849 error_at (loc
, "%q#T used where a %qT was expected",
851 return error_mark_node
;
853 return convert_to_vector (type
, e
);
855 if (code
== REAL_TYPE
|| code
== COMPLEX_TYPE
)
857 if (MAYBE_CLASS_TYPE_P (TREE_TYPE (e
)))
860 rval
= build_type_conversion (type
, e
);
863 else if (complain
& tf_error
)
865 "%q#T used where a floating point value was expected",
868 if (code
== REAL_TYPE
)
869 return convert_to_real_maybe_fold (type
, e
, dofold
);
870 else if (code
== COMPLEX_TYPE
)
871 return convert_to_complex_maybe_fold (type
, e
, dofold
);
874 /* New C++ semantics: since assignment is now based on
875 memberwise copying, if the rhs type is derived from the
876 lhs type, then we may still do a conversion. */
877 if (RECORD_OR_UNION_CODE_P (code
))
879 tree dtype
= TREE_TYPE (e
);
880 tree ctor
= NULL_TREE
;
882 dtype
= TYPE_MAIN_VARIANT (dtype
);
884 /* Conversion between aggregate types. New C++ semantics allow
885 objects of derived type to be cast to objects of base type.
886 Old semantics only allowed this between pointers.
888 There may be some ambiguity between using a constructor
889 vs. using a type conversion operator when both apply. */
893 if (abstract_virtuals_error_sfinae (NULL_TREE
, type
, complain
))
894 return error_mark_node
;
896 if (BRACE_ENCLOSED_INITIALIZER_P (ctor
))
897 ctor
= perform_implicit_conversion (type
, ctor
, complain
);
898 else if ((flags
& LOOKUP_ONLYCONVERTING
)
899 && ! (CLASS_TYPE_P (dtype
) && DERIVED_FROM_P (type
, dtype
)))
900 /* For copy-initialization, first we create a temp of the proper type
901 with a user-defined conversion sequence, then we direct-initialize
902 the target with the temp (see [dcl.init]). */
903 ctor
= build_user_type_conversion (type
, ctor
, flags
, complain
);
906 vec
<tree
, va_gc
> *ctor_vec
= make_tree_vector_single (ctor
);
907 ctor
= build_special_member_call (NULL_TREE
,
908 complete_ctor_identifier
,
910 type
, flags
, complain
);
911 release_tree_vector (ctor_vec
);
914 return build_cplus_new (type
, ctor
, complain
);
917 if (complain
& tf_error
)
919 /* If the conversion failed and expr was an invalid use of pointer to
920 member function, try to report a meaningful error. */
921 if (invalid_nonstatic_memfn_p (loc
, expr
, complain
))
922 /* We displayed the error message. */;
924 error_at (loc
, "conversion from %qT to non-scalar type %qT requested",
925 TREE_TYPE (expr
), type
);
927 return error_mark_node
;
930 /* If CALL is a call, return the callee; otherwise null. */
933 cp_get_callee (tree call
)
935 if (call
== NULL_TREE
)
937 else if (TREE_CODE (call
) == CALL_EXPR
)
938 return CALL_EXPR_FN (call
);
939 else if (TREE_CODE (call
) == AGGR_INIT_EXPR
)
940 return AGGR_INIT_EXPR_FN (call
);
944 /* FN is the callee of a CALL_EXPR or AGGR_INIT_EXPR; return the FUNCTION_DECL
948 cp_get_fndecl_from_callee (tree fn
)
952 if (TREE_CODE (fn
) == FUNCTION_DECL
)
954 tree type
= TREE_TYPE (fn
);
955 if (type
== unknown_type_node
)
957 gcc_assert (POINTER_TYPE_P (type
));
958 fn
= maybe_constant_init (fn
);
960 if (TREE_CODE (fn
) == ADDR_EXPR
)
962 fn
= TREE_OPERAND (fn
, 0);
963 if (TREE_CODE (fn
) == FUNCTION_DECL
)
969 /* Like get_callee_fndecl, but handles AGGR_INIT_EXPR as well and uses the
970 constexpr machinery. */
973 cp_get_callee_fndecl (tree call
)
975 return cp_get_fndecl_from_callee (cp_get_callee (call
));
978 /* Subroutine of convert_to_void. Warn if we're discarding something with
979 attribute [[nodiscard]]. */
982 maybe_warn_nodiscard (tree expr
, impl_conv_void implicit
)
985 if (TREE_CODE (expr
) == TARGET_EXPR
)
986 call
= TARGET_EXPR_INITIAL (expr
);
987 location_t loc
= EXPR_LOC_OR_LOC (call
, input_location
);
988 tree callee
= cp_get_callee (call
);
992 tree type
= TREE_TYPE (callee
);
993 if (TYPE_PTRMEMFUNC_P (type
))
994 type
= TYPE_PTRMEMFUNC_FN_TYPE (type
);
995 if (POINTER_TYPE_P (type
))
996 type
= TREE_TYPE (type
);
998 tree rettype
= TREE_TYPE (type
);
999 tree fn
= cp_get_fndecl_from_callee (callee
);
1000 if (implicit
!= ICV_CAST
&& fn
1001 && lookup_attribute ("nodiscard", DECL_ATTRIBUTES (fn
)))
1003 if (warning_at (loc
, OPT_Wunused_result
,
1004 "ignoring return value of %qD, "
1005 "declared with attribute nodiscard", fn
))
1006 inform (DECL_SOURCE_LOCATION (fn
), "declared here");
1008 else if (implicit
!= ICV_CAST
1009 && lookup_attribute ("nodiscard", TYPE_ATTRIBUTES (rettype
)))
1011 if (warning_at (loc
, OPT_Wunused_result
,
1012 "ignoring returned value of type %qT, "
1013 "declared with attribute nodiscard", rettype
))
1016 inform (DECL_SOURCE_LOCATION (fn
),
1017 "in call to %qD, declared here", fn
);
1018 inform (DECL_SOURCE_LOCATION (TYPE_NAME (rettype
)),
1019 "%qT declared here", rettype
);
1022 else if (TREE_CODE (expr
) == TARGET_EXPR
1023 && lookup_attribute ("warn_unused_result", TYPE_ATTRIBUTES (type
)))
1025 /* The TARGET_EXPR confuses do_warn_unused_result into thinking that the
1026 result is used, so handle that case here. */
1029 if (warning_at (loc
, OPT_Wunused_result
,
1030 "ignoring return value of %qD, "
1031 "declared with attribute warn_unused_result",
1033 inform (DECL_SOURCE_LOCATION (fn
), "declared here");
1036 warning_at (loc
, OPT_Wunused_result
,
1037 "ignoring return value of function "
1038 "declared with attribute warn_unused_result");
1042 /* When an expression is used in a void context, its value is discarded and
1043 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
1044 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
1045 in a void context. The C++ standard does not define what an `access' to an
1046 object is, but there is reason to believe that it is the lvalue to rvalue
1047 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
1048 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
1049 indicates that volatile semantics should be the same between C and C++
1050 where ever possible. C leaves it implementation defined as to what
1051 constitutes an access to a volatile. So, we interpret `*vp' as a read of
1052 the volatile object `vp' points to, unless that is an incomplete type. For
1053 volatile references we do not do this interpretation, because that would
1054 make it impossible to ignore the reference return value from functions. We
1055 issue warnings in the confusing cases.
1057 The IMPLICIT is ICV_CAST when the user is explicitly converting an expression
1058 to void via a cast. If an expression is being implicitly converted, IMPLICIT
1059 indicates the context of the implicit conversion. */
1062 convert_to_void (tree expr
, impl_conv_void implicit
, tsubst_flags_t complain
)
1064 location_t loc
= EXPR_LOC_OR_LOC (expr
, input_location
);
1066 if (expr
== error_mark_node
1067 || TREE_TYPE (expr
) == error_mark_node
)
1068 return error_mark_node
;
1070 if (implicit
== ICV_CAST
)
1071 mark_exp_read (expr
);
1076 while (TREE_CODE (exprv
) == COMPOUND_EXPR
)
1077 exprv
= TREE_OPERAND (exprv
, 1);
1079 || handled_component_p (exprv
)
1080 || INDIRECT_REF_P (exprv
))
1081 /* Expr is not being 'used' here, otherwise we whould have
1082 called mark_{rl}value_use use here, which would have in turn
1083 called mark_exp_read. Rather, we call mark_exp_read directly
1084 to avoid some warnings when
1085 -Wunused-but-set-{variable,parameter} is in effect. */
1086 mark_exp_read (exprv
);
1089 if (!TREE_TYPE (expr
))
1091 if (invalid_nonstatic_memfn_p (loc
, expr
, complain
))
1092 return error_mark_node
;
1093 if (TREE_CODE (expr
) == PSEUDO_DTOR_EXPR
)
1095 if (complain
& tf_error
)
1096 error_at (loc
, "pseudo-destructor is not called");
1097 return error_mark_node
;
1099 if (VOID_TYPE_P (TREE_TYPE (expr
)))
1101 switch (TREE_CODE (expr
))
1105 /* The two parts of a cond expr might be separate lvalues. */
1106 tree op1
= TREE_OPERAND (expr
,1);
1107 tree op2
= TREE_OPERAND (expr
,2);
1108 bool side_effects
= ((op1
&& TREE_SIDE_EFFECTS (op1
))
1109 || TREE_SIDE_EFFECTS (op2
));
1110 tree new_op1
, new_op2
;
1111 new_op1
= NULL_TREE
;
1112 if (implicit
!= ICV_CAST
&& !side_effects
)
1115 new_op1
= convert_to_void (op1
, ICV_SECOND_OF_COND
, complain
);
1116 new_op2
= convert_to_void (op2
, ICV_THIRD_OF_COND
, complain
);
1121 new_op1
= convert_to_void (op1
, ICV_CAST
, complain
);
1122 new_op2
= convert_to_void (op2
, ICV_CAST
, complain
);
1125 expr
= build3 (COND_EXPR
, TREE_TYPE (new_op2
),
1126 TREE_OPERAND (expr
, 0), new_op1
, new_op2
);
1132 /* The second part of a compound expr contains the value. */
1133 tree op1
= TREE_OPERAND (expr
,1);
1135 if (implicit
!= ICV_CAST
&& !TREE_NO_WARNING (expr
))
1136 new_op1
= convert_to_void (op1
, ICV_RIGHT_OF_COMMA
, complain
);
1138 new_op1
= convert_to_void (op1
, ICV_CAST
, complain
);
1142 tree t
= build2 (COMPOUND_EXPR
, TREE_TYPE (new_op1
),
1143 TREE_OPERAND (expr
, 0), new_op1
);
1150 case NON_LVALUE_EXPR
:
1152 /* These have already decayed to rvalue. */
1155 case CALL_EXPR
: /* We have a special meaning for volatile void fn(). */
1156 maybe_warn_nodiscard (expr
, implicit
);
1161 tree type
= TREE_TYPE (expr
);
1162 int is_reference
= TREE_CODE (TREE_TYPE (TREE_OPERAND (expr
, 0)))
1164 int is_volatile
= TYPE_VOLATILE (type
);
1165 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
1167 /* Can't load the value if we don't know the type. */
1168 if (is_volatile
&& !is_complete
)
1170 if (complain
& tf_warning
)
1174 warning_at (loc
, 0, "conversion to void will not access "
1175 "object of incomplete type %qT", type
);
1177 case ICV_SECOND_OF_COND
:
1178 warning_at (loc
, 0, "indirection will not access object of "
1179 "incomplete type %qT in second operand "
1180 "of conditional expression", type
);
1182 case ICV_THIRD_OF_COND
:
1183 warning_at (loc
, 0, "indirection will not access object of "
1184 "incomplete type %qT in third operand "
1185 "of conditional expression", type
);
1187 case ICV_RIGHT_OF_COMMA
:
1188 warning_at (loc
, 0, "indirection will not access object of "
1189 "incomplete type %qT in right operand of "
1190 "comma operator", type
);
1192 case ICV_LEFT_OF_COMMA
:
1193 warning_at (loc
, 0, "indirection will not access object of "
1194 "incomplete type %qT in left operand of "
1195 "comma operator", type
);
1198 warning_at (loc
, 0, "indirection will not access object of "
1199 "incomplete type %qT in statement", type
);
1201 case ICV_THIRD_IN_FOR
:
1202 warning_at (loc
, 0, "indirection will not access object of "
1203 "incomplete type %qT in for increment "
1204 "expression", type
);
1210 /* Don't load the value if this is an implicit dereference, or if
1211 the type needs to be handled by ctors/dtors. */
1212 else if (is_volatile
&& is_reference
)
1214 if (complain
& tf_warning
)
1218 warning_at (loc
, 0, "conversion to void will not access "
1219 "object of type %qT", type
);
1221 case ICV_SECOND_OF_COND
:
1222 warning_at (loc
, 0, "implicit dereference will not access "
1223 "object of type %qT in second operand of "
1224 "conditional expression", type
);
1226 case ICV_THIRD_OF_COND
:
1227 warning_at (loc
, 0, "implicit dereference will not access "
1228 "object of type %qT in third operand of "
1229 "conditional expression", type
);
1231 case ICV_RIGHT_OF_COMMA
:
1232 warning_at (loc
, 0, "implicit dereference will not access "
1233 "object of type %qT in right operand of "
1234 "comma operator", type
);
1236 case ICV_LEFT_OF_COMMA
:
1237 warning_at (loc
, 0, "implicit dereference will not access "
1238 "object of type %qT in left operand of comma "
1242 warning_at (loc
, 0, "implicit dereference will not access "
1243 "object of type %qT in statement", type
);
1245 case ICV_THIRD_IN_FOR
:
1246 warning_at (loc
, 0, "implicit dereference will not access "
1247 "object of type %qT in for increment expression",
1254 else if (is_volatile
&& TREE_ADDRESSABLE (type
))
1256 if (complain
& tf_warning
)
1260 warning_at (loc
, 0, "conversion to void will not access "
1261 "object of non-trivially-copyable type %qT",
1264 case ICV_SECOND_OF_COND
:
1265 warning_at (loc
, 0, "indirection will not access object of "
1266 "non-trivially-copyable type %qT in second "
1267 "operand of conditional expression", type
);
1269 case ICV_THIRD_OF_COND
:
1270 warning_at (loc
, 0, "indirection will not access object of "
1271 "non-trivially-copyable type %qT in third "
1272 "operand of conditional expression", type
);
1274 case ICV_RIGHT_OF_COMMA
:
1275 warning_at (loc
, 0, "indirection will not access object of "
1276 "non-trivially-copyable type %qT in right "
1277 "operand of comma operator", type
);
1279 case ICV_LEFT_OF_COMMA
:
1280 warning_at (loc
, 0, "indirection will not access object of "
1281 "non-trivially-copyable type %qT in left "
1282 "operand of comma operator", type
);
1285 warning_at (loc
, 0, "indirection will not access object of "
1286 "non-trivially-copyable type %qT in statement",
1289 case ICV_THIRD_IN_FOR
:
1290 warning_at (loc
, 0, "indirection will not access object of "
1291 "non-trivially-copyable type %qT in for "
1292 "increment expression", type
);
1298 if (is_reference
|| !is_volatile
|| !is_complete
|| TREE_ADDRESSABLE (type
))
1300 /* Emit a warning (if enabled) when the "effect-less" INDIRECT_REF
1301 operation is stripped off. Note that we don't warn about
1302 - an expression with TREE_NO_WARNING set. (For an example of
1303 such expressions, see build_over_call in call.c.)
1304 - automatic dereferencing of references, since the user cannot
1305 control it. (See also warn_if_unused_value() in c-common.c.) */
1306 if (warn_unused_value
1307 && implicit
!= ICV_CAST
1308 && (complain
& tf_warning
)
1309 && !TREE_NO_WARNING (expr
)
1311 warning_at (loc
, OPT_Wunused_value
, "value computed is not used");
1312 expr
= TREE_OPERAND (expr
, 0);
1320 /* External variables might be incomplete. */
1321 tree type
= TREE_TYPE (expr
);
1322 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
1324 if (TYPE_VOLATILE (type
) && !is_complete
&& (complain
& tf_warning
))
1328 warning_at (loc
, 0, "conversion to void will not access "
1329 "object %qE of incomplete type %qT", expr
, type
);
1331 case ICV_SECOND_OF_COND
:
1332 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1333 "not be accessed in second operand of "
1334 "conditional expression", expr
, type
);
1336 case ICV_THIRD_OF_COND
:
1337 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1338 "not be accessed in third operand of "
1339 "conditional expression", expr
, type
);
1341 case ICV_RIGHT_OF_COMMA
:
1342 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1343 "not be accessed in right operand of comma operator",
1346 case ICV_LEFT_OF_COMMA
:
1347 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1348 "not be accessed in left operand of comma operator",
1352 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1353 "not be accessed in statement", expr
, type
);
1355 case ICV_THIRD_IN_FOR
:
1356 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1357 "not be accessed in for increment expression",
1368 /* Don't bother with the temporary object returned from a function if
1369 we don't use it, don't need to destroy it, and won't abort in
1370 assign_temp. We'll still
1371 allocate space for it in expand_call or declare_return_variable,
1372 but we don't need to track it through all the tree phases. */
1373 if (TARGET_EXPR_IMPLICIT_P (expr
)
1374 && !TREE_ADDRESSABLE (TREE_TYPE (expr
)))
1376 tree init
= TARGET_EXPR_INITIAL (expr
);
1377 if (TREE_CODE (init
) == AGGR_INIT_EXPR
1378 && !AGGR_INIT_VIA_CTOR_P (init
))
1380 tree fn
= AGGR_INIT_EXPR_FN (init
);
1381 expr
= build_call_array_loc (input_location
,
1382 TREE_TYPE (TREE_TYPE
1385 aggr_init_expr_nargs (init
),
1386 AGGR_INIT_EXPR_ARGP (init
));
1389 maybe_warn_nodiscard (expr
, implicit
);
1394 expr
= resolve_nondeduced_context (expr
, complain
);
1398 if (TREE_CODE (probe
) == ADDR_EXPR
)
1399 probe
= TREE_OPERAND (expr
, 0);
1400 if (type_unknown_p (probe
))
1402 /* [over.over] enumerates the places where we can take the address
1403 of an overloaded function, and this is not one of them. */
1404 if (complain
& tf_error
)
1408 error_at (loc
, "conversion to void "
1409 "cannot resolve address of overloaded function");
1411 case ICV_SECOND_OF_COND
:
1412 error_at (loc
, "second operand of conditional expression "
1413 "cannot resolve address of overloaded function");
1415 case ICV_THIRD_OF_COND
:
1416 error_at (loc
, "third operand of conditional expression "
1417 "cannot resolve address of overloaded function");
1419 case ICV_RIGHT_OF_COMMA
:
1420 error_at (loc
, "right operand of comma operator "
1421 "cannot resolve address of overloaded function");
1423 case ICV_LEFT_OF_COMMA
:
1424 error_at (loc
, "left operand of comma operator "
1425 "cannot resolve address of overloaded function");
1428 error_at (loc
, "statement "
1429 "cannot resolve address of overloaded function");
1431 case ICV_THIRD_IN_FOR
:
1432 error_at (loc
, "for increment expression "
1433 "cannot resolve address of overloaded function");
1437 return error_mark_node
;
1440 else if (implicit
!= ICV_CAST
&& probe
== expr
&& is_overloaded_fn (probe
))
1442 /* Only warn when there is no &. */
1443 if (complain
& tf_warning
)
1446 case ICV_SECOND_OF_COND
:
1447 warning_at (loc
, OPT_Waddress
,
1448 "second operand of conditional expression "
1449 "is a reference, not call, to function %qE", expr
);
1451 case ICV_THIRD_OF_COND
:
1452 warning_at (loc
, OPT_Waddress
,
1453 "third operand of conditional expression "
1454 "is a reference, not call, to function %qE", expr
);
1456 case ICV_RIGHT_OF_COMMA
:
1457 warning_at (loc
, OPT_Waddress
,
1458 "right operand of comma operator "
1459 "is a reference, not call, to function %qE", expr
);
1461 case ICV_LEFT_OF_COMMA
:
1462 warning_at (loc
, OPT_Waddress
,
1463 "left operand of comma operator "
1464 "is a reference, not call, to function %qE", expr
);
1467 warning_at (loc
, OPT_Waddress
,
1468 "statement is a reference, not call, to function %qE",
1471 case ICV_THIRD_IN_FOR
:
1472 warning_at (loc
, OPT_Waddress
,
1473 "for increment expression "
1474 "is a reference, not call, to function %qE", expr
);
1480 if (TREE_CODE (expr
) == COMPONENT_REF
)
1481 expr
= TREE_OPERAND (expr
, 0);
1485 if (expr
!= error_mark_node
&& !VOID_TYPE_P (TREE_TYPE (expr
)))
1487 if (implicit
!= ICV_CAST
1488 && warn_unused_value
1489 && !TREE_NO_WARNING (expr
)
1490 && !processing_template_decl
)
1492 /* The middle end does not warn about expressions that have
1493 been explicitly cast to void, so we must do so here. */
1494 if (!TREE_SIDE_EFFECTS (expr
)) {
1495 if (complain
& tf_warning
)
1498 case ICV_SECOND_OF_COND
:
1499 warning_at (loc
, OPT_Wunused_value
,
1500 "second operand of conditional expression "
1503 case ICV_THIRD_OF_COND
:
1504 warning_at (loc
, OPT_Wunused_value
,
1505 "third operand of conditional expression "
1508 case ICV_RIGHT_OF_COMMA
:
1509 warning_at (loc
, OPT_Wunused_value
,
1510 "right operand of comma operator has no effect");
1512 case ICV_LEFT_OF_COMMA
:
1513 warning_at (loc
, OPT_Wunused_value
,
1514 "left operand of comma operator has no effect");
1517 warning_at (loc
, OPT_Wunused_value
,
1518 "statement has no effect");
1520 case ICV_THIRD_IN_FOR
:
1521 warning_at (loc
, OPT_Wunused_value
,
1522 "for increment expression has no effect");
1531 enum tree_code code
;
1532 enum tree_code_class tclass
;
1535 /* We might like to warn about (say) "(int) f()", as the
1536 cast has no effect, but the compiler itself will
1537 generate implicit conversions under some
1538 circumstances. (For example a block copy will be
1539 turned into a call to "__builtin_memcpy", with a
1540 conversion of the return value to an appropriate
1541 type.) So, to avoid false positives, we strip
1542 conversions. Do not use STRIP_NOPs because it will
1543 not strip conversions to "void", as that is not a
1544 mode-preserving conversion. */
1545 while (TREE_CODE (e
) == NOP_EXPR
)
1546 e
= TREE_OPERAND (e
, 0);
1548 code
= TREE_CODE (e
);
1549 tclass
= TREE_CODE_CLASS (code
);
1550 if ((tclass
== tcc_comparison
1551 || tclass
== tcc_unary
1552 || (tclass
== tcc_binary
1553 && !(code
== MODIFY_EXPR
1554 || code
== INIT_EXPR
1555 || code
== PREDECREMENT_EXPR
1556 || code
== PREINCREMENT_EXPR
1557 || code
== POSTDECREMENT_EXPR
1558 || code
== POSTINCREMENT_EXPR
))
1559 || code
== VEC_PERM_EXPR
1560 || code
== VEC_COND_EXPR
)
1561 && (complain
& tf_warning
))
1562 warning_at (loc
, OPT_Wunused_value
, "value computed is not used");
1565 expr
= build1 (CONVERT_EXPR
, void_type_node
, expr
);
1567 if (! TREE_SIDE_EFFECTS (expr
))
1572 /* Create an expression whose value is that of EXPR,
1573 converted to type TYPE. The TREE_TYPE of the value
1574 is always TYPE. This function implements all reasonable
1575 conversions; callers should filter out those that are
1576 not permitted by the language being compiled.
1578 Most of this routine is from build_reinterpret_cast.
1580 The back end cannot call cp_convert (what was convert) because
1581 conversions to/from basetypes may involve memory references
1582 (vbases) and adding or subtracting small values (multiple
1583 inheritance), but it calls convert from the constant folding code
1584 on subtrees of already built trees after it has ripped them apart.
1586 Also, if we ever support range variables, we'll probably also have to
1587 do a little bit more work. */
1590 convert (tree type
, tree expr
)
1594 if (type
== error_mark_node
|| expr
== error_mark_node
)
1595 return error_mark_node
;
1597 intype
= TREE_TYPE (expr
);
1599 if (POINTER_TYPE_P (type
) && POINTER_TYPE_P (intype
))
1600 return build_nop (type
, expr
);
1602 return ocp_convert (type
, expr
, CONV_BACKEND_CONVERT
,
1603 LOOKUP_NORMAL
|LOOKUP_NO_CONVERSION
,
1604 tf_warning_or_error
);
1607 /* Like cp_convert, except permit conversions to take place which
1608 are not normally allowed due to access restrictions
1609 (such as conversion from sub-type to private super-type). */
1612 convert_force (tree type
, tree expr
, int convtype
, tsubst_flags_t complain
)
1615 enum tree_code code
= TREE_CODE (type
);
1617 if (code
== REFERENCE_TYPE
)
1618 return convert_to_reference (type
, e
, CONV_C_CAST
, 0,
1619 NULL_TREE
, complain
);
1621 if (code
== POINTER_TYPE
)
1622 return convert_to_pointer_force (type
, e
, complain
);
1624 /* From typeck.c convert_for_assignment */
1625 if (((TYPE_PTR_P (TREE_TYPE (e
)) && TREE_CODE (e
) == ADDR_EXPR
1626 && TREE_CODE (TREE_TYPE (TREE_TYPE (e
))) == METHOD_TYPE
)
1627 || integer_zerop (e
)
1628 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e
)))
1629 && TYPE_PTRMEMFUNC_P (type
))
1630 /* compatible pointer to member functions. */
1631 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), e
, 1,
1632 /*c_cast_p=*/1, complain
);
1634 return ocp_convert (type
, e
, CONV_C_CAST
|convtype
, LOOKUP_NORMAL
, complain
);
1637 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1638 exists, return the attempted conversion. This may
1639 return ERROR_MARK_NODE if the conversion is not
1640 allowed (references private members, etc).
1641 If no conversion exists, NULL_TREE is returned.
1643 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1644 object parameter, or by the second standard conversion sequence if
1645 that doesn't do it. This will probably wait for an overloading rewrite.
1649 build_type_conversion (tree xtype
, tree expr
)
1651 /* C++: check to see if we can convert this aggregate type
1652 into the required type. */
1653 return build_user_type_conversion (xtype
, expr
, LOOKUP_NORMAL
,
1654 tf_warning_or_error
);
1657 /* Convert the given EXPR to one of a group of types suitable for use in an
1658 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1659 which indicates which types are suitable. If COMPLAIN is true, complain
1660 about ambiguity; otherwise, the caller will deal with it. */
1663 build_expr_type_conversion (int desires
, tree expr
, bool complain
)
1665 tree basetype
= TREE_TYPE (expr
);
1666 tree conv
= NULL_TREE
;
1667 tree winner
= NULL_TREE
;
1669 if (expr
== null_node
1670 && (desires
& WANT_INT
)
1671 && !(desires
& WANT_NULL
))
1673 source_location loc
=
1674 expansion_point_location_if_in_system_header (input_location
);
1676 warning_at (loc
, OPT_Wconversion_null
,
1677 "converting NULL to non-pointer type");
1680 if (basetype
== error_mark_node
)
1681 return error_mark_node
;
1683 if (! MAYBE_CLASS_TYPE_P (basetype
))
1684 switch (TREE_CODE (basetype
))
1687 if ((desires
& WANT_NULL
) && null_ptr_cst_p (expr
))
1692 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1694 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1696 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1698 return (desires
& WANT_POINTER
) ? expr
: NULL_TREE
;
1702 return (desires
& WANT_POINTER
) ? decay_conversion (expr
,
1703 tf_warning_or_error
)
1708 if ((desires
& WANT_VECTOR_OR_COMPLEX
) == 0)
1710 switch (TREE_CODE (TREE_TYPE (basetype
)))
1714 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1716 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1718 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1727 /* The code for conversions from class type is currently only used for
1728 delete expressions. Other expressions are handled by build_new_op. */
1729 if (!complete_type_or_maybe_complain (basetype
, expr
, complain
))
1730 return error_mark_node
;
1731 if (!TYPE_HAS_CONVERSION (basetype
))
1734 for (conv
= lookup_conversions (basetype
); conv
; conv
= TREE_CHAIN (conv
))
1738 tree cand
= TREE_VALUE (conv
);
1739 cand
= OVL_CURRENT (cand
);
1741 if (winner
&& winner
== cand
)
1744 if (DECL_NONCONVERTING_P (cand
))
1747 candidate
= non_reference (TREE_TYPE (TREE_TYPE (cand
)));
1749 switch (TREE_CODE (candidate
))
1753 win
= (desires
& WANT_INT
); break;
1755 win
= (desires
& WANT_ENUM
); break;
1757 win
= (desires
& WANT_FLOAT
); break;
1759 win
= (desires
& WANT_POINTER
); break;
1763 if ((desires
& WANT_VECTOR_OR_COMPLEX
) == 0)
1765 switch (TREE_CODE (TREE_TYPE (candidate
)))
1769 win
= (desires
& WANT_INT
); break;
1771 win
= (desires
& WANT_ENUM
); break;
1773 win
= (desires
& WANT_FLOAT
); break;
1780 /* A wildcard could be instantiated to match any desired
1781 type, but we can't deduce the template argument. */
1782 if (WILDCARD_TYPE_P (candidate
))
1789 if (TREE_CODE (cand
) == TEMPLATE_DECL
)
1792 error ("default type conversion can't deduce template"
1793 " argument for %qD", cand
);
1794 return error_mark_node
;
1800 = non_reference (TREE_TYPE (TREE_TYPE (winner
)));
1802 if (!same_type_ignoring_top_level_qualifiers_p (winner_type
,
1807 error ("ambiguous default type conversion from %qT",
1809 inform (input_location
,
1810 " candidate conversions include %qD and %qD",
1813 return error_mark_node
;
1823 tree type
= non_reference (TREE_TYPE (TREE_TYPE (winner
)));
1824 return build_user_type_conversion (type
, expr
, LOOKUP_NORMAL
,
1825 tf_warning_or_error
);
1831 /* Implements integral promotion (4.1) and float->double promotion. */
1834 type_promotes_to (tree type
)
1838 if (type
== error_mark_node
)
1839 return error_mark_node
;
1841 type
= TYPE_MAIN_VARIANT (type
);
1843 /* Check for promotions of target-defined types first. */
1844 promoted_type
= targetm
.promoted_type (type
);
1846 return promoted_type
;
1848 /* bool always promotes to int (not unsigned), even if it's the same
1850 if (TREE_CODE (type
) == BOOLEAN_TYPE
)
1851 type
= integer_type_node
;
1853 /* Normally convert enums to int, but convert wide enums to something
1854 wider. Scoped enums don't promote, but pretend they do for backward
1855 ABI bug compatibility wrt varargs. */
1856 else if (TREE_CODE (type
) == ENUMERAL_TYPE
1857 || type
== char16_type_node
1858 || type
== char32_type_node
1859 || type
== wchar_type_node
)
1861 int precision
= MAX (TYPE_PRECISION (type
),
1862 TYPE_PRECISION (integer_type_node
));
1863 tree totype
= c_common_type_for_size (precision
, 0);
1865 if (TREE_CODE (prom
) == ENUMERAL_TYPE
)
1866 prom
= ENUM_UNDERLYING_TYPE (prom
);
1867 if (TYPE_UNSIGNED (prom
)
1868 && ! int_fits_type_p (TYPE_MAX_VALUE (prom
), totype
))
1869 prom
= c_common_type_for_size (precision
, 1);
1872 if (SCOPED_ENUM_P (type
))
1874 if (abi_version_crosses (6)
1875 && TYPE_MODE (prom
) != TYPE_MODE (type
))
1876 warning (OPT_Wabi
, "scoped enum %qT passed through ... as "
1877 "%qT before -fabi-version=6, %qT after",
1878 type
, prom
, ENUM_UNDERLYING_TYPE (type
));
1879 if (!abi_version_at_least (6))
1885 else if (c_promoting_integer_type_p (type
))
1887 /* Retain unsignedness if really not getting bigger. */
1888 if (TYPE_UNSIGNED (type
)
1889 && TYPE_PRECISION (type
) == TYPE_PRECISION (integer_type_node
))
1890 type
= unsigned_type_node
;
1892 type
= integer_type_node
;
1894 else if (type
== float_type_node
)
1895 type
= double_type_node
;
1900 /* The routines below this point are carefully written to conform to
1901 the standard. They use the same terminology, and follow the rules
1902 closely. Although they are used only in pt.c at the moment, they
1903 should presumably be used everywhere in the future. */
1905 /* Attempt to perform qualification conversions on EXPR to convert it
1906 to TYPE. Return the resulting expression, or error_mark_node if
1907 the conversion was impossible. */
1910 perform_qualification_conversions (tree type
, tree expr
)
1914 expr_type
= TREE_TYPE (expr
);
1916 if (same_type_p (type
, expr_type
))
1918 else if (TYPE_PTR_P (type
) && TYPE_PTR_P (expr_type
)
1919 && comp_ptr_ttypes (TREE_TYPE (type
), TREE_TYPE (expr_type
)))
1920 return build_nop (type
, expr
);
1921 else if (TYPE_PTRMEM_P (type
) && TYPE_PTRMEM_P (expr_type
)
1922 && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type
),
1923 TYPE_PTRMEM_CLASS_TYPE (expr_type
))
1924 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type
),
1925 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type
)))
1926 return build_nop (type
, expr
);
1928 return error_mark_node
;
1931 /* True iff T is a transaction-safe function type. */
1934 tx_safe_fn_type_p (tree t
)
1936 if (TREE_CODE (t
) != FUNCTION_TYPE
1937 && TREE_CODE (t
) != METHOD_TYPE
)
1939 return !!lookup_attribute ("transaction_safe", TYPE_ATTRIBUTES (t
));
1942 /* Return the transaction-unsafe variant of transaction-safe function type
1946 tx_unsafe_fn_variant (tree t
)
1948 gcc_assert (tx_safe_fn_type_p (t
));
1949 tree attrs
= remove_attribute ("transaction_safe",
1950 TYPE_ATTRIBUTES (t
));
1951 return cp_build_type_attribute_variant (t
, attrs
);
1954 /* Return true iff FROM can convert to TO by a transaction-safety
1958 can_convert_tx_safety (tree to
, tree from
)
1960 return (flag_tm
&& tx_safe_fn_type_p (from
)
1961 && same_type_p (to
, tx_unsafe_fn_variant (from
)));