1 /* Language-level data type conversion for GNU C++.
2 Copyright (C) 1987-2018 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"
36 #include "stringpool.h"
39 static tree
convert_to_pointer_force (tree
, tree
, tsubst_flags_t
);
40 static tree
build_type_conversion (tree
, tree
);
41 static tree
build_up_reference (tree
, tree
, int, tree
, tsubst_flags_t
);
42 static void diagnose_ref_binding (location_t
, tree
, tree
, tree
);
44 /* Change of width--truncation and extension of integers or reals--
45 is represented with NOP_EXPR. Proper functioning of many things
46 assumes that no other conversions can be NOP_EXPRs.
48 Conversion between integer and pointer is represented with CONVERT_EXPR.
49 Converting integer to real uses FLOAT_EXPR
50 and real to integer uses FIX_TRUNC_EXPR.
52 Here is a list of all the functions that assume that widening and
53 narrowing is always done with a NOP_EXPR:
54 In convert.c, convert_to_integer[_maybe_fold].
55 In c-typeck.c, build_binary_op_nodefault (boolean ops),
56 and c_common_truthvalue_conversion.
57 In expr.c: expand_expr, for operands of a MULT_EXPR.
58 In fold-const.c: fold.
59 In tree.c: get_narrower and get_unwidened.
61 C++: in multiple-inheritance, converting between pointers may involve
62 adjusting them by a delta stored within the class definition. */
64 /* Subroutines of `convert'. */
66 /* if converting pointer to pointer
67 if dealing with classes, check for derived->base or vice versa
68 else if dealing with method pointers, delegate
70 else if converting class, pass off to build_type_conversion
71 else try C-style pointer conversion. */
74 cp_convert_to_pointer (tree type
, tree expr
, bool dofold
,
75 tsubst_flags_t complain
)
77 tree intype
= TREE_TYPE (expr
);
80 location_t loc
= EXPR_LOC_OR_LOC (expr
, input_location
);
82 if (intype
== error_mark_node
)
83 return error_mark_node
;
85 if (MAYBE_CLASS_TYPE_P (intype
))
87 intype
= complete_type (intype
);
88 if (!COMPLETE_TYPE_P (intype
))
90 if (complain
& tf_error
)
91 error_at (loc
, "can%'t convert from incomplete type %qH to %qI",
93 return error_mark_node
;
96 rval
= build_type_conversion (type
, expr
);
99 if ((complain
& tf_error
)
100 && rval
== error_mark_node
)
101 error_at (loc
, "conversion of %qE from %qH to %qI is ambiguous",
107 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
108 if (TYPE_PTR_P (type
)
109 && (TREE_CODE (TREE_TYPE (type
)) == FUNCTION_TYPE
110 || VOID_TYPE_P (TREE_TYPE (type
))))
112 if (TYPE_PTRMEMFUNC_P (intype
)
113 || TREE_CODE (intype
) == METHOD_TYPE
)
114 return convert_member_func_to_ptr (type
, expr
, complain
);
115 if (TYPE_PTR_P (TREE_TYPE (expr
)))
116 return build_nop (type
, expr
);
117 intype
= TREE_TYPE (expr
);
120 if (expr
== error_mark_node
)
121 return error_mark_node
;
123 form
= TREE_CODE (intype
);
125 if (POINTER_TYPE_P (intype
))
127 intype
= TYPE_MAIN_VARIANT (intype
);
129 if (TYPE_MAIN_VARIANT (type
) != intype
131 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
132 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type
))
133 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype
))
134 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
136 enum tree_code code
= PLUS_EXPR
;
142 intype_class
= TREE_TYPE (intype
);
143 type_class
= TREE_TYPE (type
);
145 same_p
= same_type_p (TYPE_MAIN_VARIANT (intype_class
),
146 TYPE_MAIN_VARIANT (type_class
));
148 /* Try derived to base conversion. */
150 binfo
= lookup_base (intype_class
, type_class
, ba_check
,
152 if (!same_p
&& !binfo
)
154 /* Try base to derived conversion. */
155 binfo
= lookup_base (type_class
, intype_class
, ba_check
,
159 if (binfo
== error_mark_node
)
160 return error_mark_node
;
164 expr
= build_base_path (code
, expr
, binfo
, 0, complain
);
165 /* Add any qualifier conversions. */
166 return build_nop (type
, expr
);
170 if (TYPE_PTRMEMFUNC_P (type
))
172 if (complain
& tf_error
)
173 error_at (loc
, "cannot convert %qE from type %qH to type %qI",
175 return error_mark_node
;
178 return build_nop (type
, expr
);
180 else if ((TYPE_PTRDATAMEM_P (type
) && TYPE_PTRDATAMEM_P (intype
))
181 || (TYPE_PTRMEMFUNC_P (type
) && TYPE_PTRMEMFUNC_P (intype
)))
182 return convert_ptrmem (type
, expr
, /*allow_inverse_p=*/false,
183 /*c_cast_p=*/false, complain
);
184 else if (TYPE_PTRMEMFUNC_P (intype
))
188 if (TREE_CODE (expr
) == PTRMEM_CST
)
189 return cp_convert_to_pointer (type
, PTRMEM_CST_MEMBER (expr
),
191 else if (TREE_CODE (expr
) == OFFSET_REF
)
193 tree object
= TREE_OPERAND (expr
, 0);
194 return get_member_function_from_ptrfunc (&object
,
195 TREE_OPERAND (expr
, 1),
199 if (complain
& tf_error
)
200 error_at (loc
, "cannot convert %qE from type %qH to type %qI",
202 return error_mark_node
;
205 if (null_ptr_cst_p (expr
))
207 if (TYPE_PTRMEMFUNC_P (type
))
208 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), expr
, 0,
209 /*c_cast_p=*/false, complain
);
211 if (complain
& tf_warning
)
212 maybe_warn_zero_as_null_pointer_constant (expr
, loc
);
214 /* A NULL pointer-to-data-member is represented by -1, not by
216 tree val
= (TYPE_PTRDATAMEM_P (type
)
217 ? build_int_cst_type (type
, -1)
218 : build_int_cst (type
, 0));
220 return (TREE_SIDE_EFFECTS (expr
)
221 ? build2 (COMPOUND_EXPR
, type
, expr
, val
) : val
);
223 else if (TYPE_PTRMEM_P (type
) && INTEGRAL_CODE_P (form
))
225 if (complain
& tf_error
)
226 error_at (loc
, "invalid conversion from %qH to %qI", intype
, type
);
227 return error_mark_node
;
230 if (INTEGRAL_CODE_P (form
))
232 if (TYPE_PRECISION (intype
) == POINTER_SIZE
)
233 return build1 (CONVERT_EXPR
, type
, expr
);
234 expr
= cp_convert (c_common_type_for_size (POINTER_SIZE
, 0), expr
,
236 /* Modes may be different but sizes should be the same. There
237 is supposed to be some integral type that is the same width
239 gcc_assert (GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (TREE_TYPE (expr
)))
240 == GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (type
)));
242 /* FIXME needed because convert_to_pointer_maybe_fold still folds
243 conversion of constants. */
245 return build1 (CONVERT_EXPR
, type
, expr
);
247 return convert_to_pointer_maybe_fold (type
, expr
, dofold
);
250 if (type_unknown_p (expr
))
251 return instantiate_type (type
, expr
, complain
);
253 if (complain
& tf_error
)
254 error_at (loc
, "cannot convert %qE from type %qH to type %qI",
256 return error_mark_node
;
259 /* Like convert, except permit conversions to take place which
260 are not normally allowed due to access restrictions
261 (such as conversion from sub-type to private super-type). */
264 convert_to_pointer_force (tree type
, tree expr
, tsubst_flags_t complain
)
266 tree intype
= TREE_TYPE (expr
);
267 enum tree_code form
= TREE_CODE (intype
);
269 if (form
== POINTER_TYPE
)
271 intype
= TYPE_MAIN_VARIANT (intype
);
273 if (TYPE_MAIN_VARIANT (type
) != intype
274 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
275 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type
))
276 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype
))
277 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
279 enum tree_code code
= PLUS_EXPR
;
282 binfo
= lookup_base (TREE_TYPE (intype
), TREE_TYPE (type
),
283 ba_unique
, NULL
, complain
);
286 binfo
= lookup_base (TREE_TYPE (type
), TREE_TYPE (intype
),
287 ba_unique
, NULL
, complain
);
290 if (binfo
== error_mark_node
)
291 return error_mark_node
;
294 expr
= build_base_path (code
, expr
, binfo
, 0, complain
);
295 if (expr
== error_mark_node
)
296 return error_mark_node
;
297 /* Add any qualifier conversions. */
298 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr
)),
300 expr
= build_nop (type
, expr
);
306 return cp_convert_to_pointer (type
, expr
, /*fold*/false, complain
);
309 /* We are passing something to a function which requires a reference.
310 The type we are interested in is in TYPE. The initial
311 value we have to begin with is in ARG.
313 FLAGS controls how we manage access checking.
314 DIRECT_BIND in FLAGS controls how any temporaries are generated.
315 If DIRECT_BIND is set, DECL is the reference we're binding to. */
318 build_up_reference (tree type
, tree arg
, int flags
, tree decl
,
319 tsubst_flags_t complain
)
322 tree argtype
= TREE_TYPE (arg
);
323 tree target_type
= TREE_TYPE (type
);
325 gcc_assert (TREE_CODE (type
) == REFERENCE_TYPE
);
327 if ((flags
& DIRECT_BIND
) && ! lvalue_p (arg
))
329 /* Create a new temporary variable. We can't just use a TARGET_EXPR
330 here because it needs to live as long as DECL. */
333 arg
= make_temporary_var_for_ref_to_temp (decl
, target_type
);
335 /* Process the initializer for the declaration. */
336 DECL_INITIAL (arg
) = targ
;
337 cp_finish_decl (arg
, targ
, /*init_const_expr_p=*/false, NULL_TREE
,
338 LOOKUP_ONLYCONVERTING
|DIRECT_BIND
);
340 else if (!(flags
& DIRECT_BIND
) && ! obvalue_p (arg
))
341 return get_target_expr_sfinae (arg
, complain
);
343 /* If we had a way to wrap this up, and say, if we ever needed its
344 address, transform all occurrences of the register, into a memory
345 reference we could win better. */
346 rval
= cp_build_addr_expr (arg
, complain
);
347 if (rval
== error_mark_node
)
348 return error_mark_node
;
350 if ((flags
& LOOKUP_PROTECT
)
351 && TYPE_MAIN_VARIANT (argtype
) != TYPE_MAIN_VARIANT (target_type
)
352 && MAYBE_CLASS_TYPE_P (argtype
)
353 && MAYBE_CLASS_TYPE_P (target_type
))
355 /* We go through lookup_base for the access control. */
356 tree binfo
= lookup_base (argtype
, target_type
, ba_check
,
358 if (binfo
== error_mark_node
)
359 return error_mark_node
;
360 if (binfo
== NULL_TREE
)
361 return error_not_base_type (target_type
, argtype
);
362 rval
= build_base_path (PLUS_EXPR
, rval
, binfo
, 1, complain
);
366 = convert_to_pointer_force (build_pointer_type (target_type
),
368 return build_nop (type
, rval
);
371 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
372 INTYPE is the original rvalue type and DECL is an optional _DECL node
375 [dcl.init.ref] says that if an rvalue is used to
376 initialize a reference, then the reference must be to a
377 non-volatile const type. */
380 diagnose_ref_binding (location_t loc
, tree reftype
, tree intype
, tree decl
)
382 tree ttl
= TREE_TYPE (reftype
);
384 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl
))
388 if (CP_TYPE_VOLATILE_P (ttl
) && decl
)
389 msg
= G_("initialization of volatile reference type %q#T from "
390 "rvalue of type %qT");
391 else if (CP_TYPE_VOLATILE_P (ttl
))
392 msg
= G_("conversion to volatile reference type %q#T "
393 "from rvalue of type %qT");
395 msg
= G_("initialization of non-const reference type %q#T from "
396 "rvalue of type %qT");
398 msg
= G_("conversion to non-const reference type %q#T from "
399 "rvalue of type %qT");
401 permerror (loc
, msg
, reftype
, intype
);
405 /* For C++: Only need to do one-level references, but cannot
406 get tripped up on signed/unsigned differences.
408 DECL is either NULL_TREE or the _DECL node for a reference that is being
409 initialized. It can be error_mark_node if we don't know the _DECL but
410 we know it's an initialization. */
413 convert_to_reference (tree reftype
, tree expr
, int convtype
,
414 int flags
, tree decl
, tsubst_flags_t complain
)
416 tree type
= TYPE_MAIN_VARIANT (TREE_TYPE (reftype
));
418 tree rval
= NULL_TREE
;
419 tree rval_as_conversion
= NULL_TREE
;
420 bool can_convert_intype_to_type
;
421 location_t loc
= EXPR_LOC_OR_LOC (expr
, input_location
);
423 if (TREE_CODE (type
) == FUNCTION_TYPE
424 && TREE_TYPE (expr
) == unknown_type_node
)
425 expr
= instantiate_type (type
, expr
, complain
);
427 if (expr
== error_mark_node
)
428 return error_mark_node
;
430 intype
= TREE_TYPE (expr
);
432 gcc_assert (TREE_CODE (intype
) != REFERENCE_TYPE
);
433 gcc_assert (TREE_CODE (reftype
) == REFERENCE_TYPE
);
435 intype
= TYPE_MAIN_VARIANT (intype
);
437 can_convert_intype_to_type
= can_convert_standard (type
, intype
, complain
);
439 if (!can_convert_intype_to_type
440 && (convtype
& CONV_IMPLICIT
) && MAYBE_CLASS_TYPE_P (intype
)
441 && ! (flags
& LOOKUP_NO_CONVERSION
))
443 /* Look for a user-defined conversion to lvalue that we can use. */
446 = build_type_conversion (reftype
, expr
);
448 if (rval_as_conversion
&& rval_as_conversion
!= error_mark_node
449 && lvalue_p (rval_as_conversion
))
451 expr
= rval_as_conversion
;
452 rval_as_conversion
= NULL_TREE
;
454 can_convert_intype_to_type
= 1;
458 if (((convtype
& CONV_STATIC
)
459 && can_convert_standard (intype
, type
, complain
))
460 || ((convtype
& CONV_IMPLICIT
) && can_convert_intype_to_type
))
463 tree ttl
= TREE_TYPE (reftype
);
464 tree ttr
= lvalue_type (expr
);
466 if ((complain
& tf_error
)
467 && ! lvalue_p (expr
))
468 diagnose_ref_binding (loc
, reftype
, intype
, decl
);
470 if (! (convtype
& CONV_CONST
)
471 && !at_least_as_qualified_p (ttl
, ttr
))
473 if (complain
& tf_error
)
474 permerror (loc
, "conversion from %qH to %qI discards qualifiers",
477 return error_mark_node
;
481 return build_up_reference (reftype
, expr
, flags
, decl
, complain
);
483 else if ((convtype
& CONV_REINTERPRET
) && obvalue_p (expr
))
485 /* When casting an lvalue to a reference type, just convert into
486 a pointer to the new type and deference it. This is allowed
487 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
488 should be done directly (jason). (int &)ri ---> *(int*)&ri */
490 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
492 if ((complain
& tf_warning
)
493 && TYPE_PTR_P (intype
)
494 && (comptypes (TREE_TYPE (intype
), type
,
495 COMPARE_BASE
| COMPARE_DERIVED
)))
496 warning_at (loc
, 0, "casting %qT to %qT does not dereference pointer",
499 rval
= cp_build_addr_expr (expr
, complain
);
500 if (rval
!= error_mark_node
)
501 rval
= convert_force (build_pointer_type (TREE_TYPE (reftype
)),
503 if (rval
!= error_mark_node
)
504 rval
= build1 (NOP_EXPR
, reftype
, rval
);
508 rval
= convert_for_initialization (NULL_TREE
, type
, expr
, flags
,
509 ICR_CONVERTING
, 0, 0, complain
);
510 if (rval
== NULL_TREE
|| rval
== error_mark_node
)
512 if (complain
& tf_error
)
513 diagnose_ref_binding (loc
, reftype
, intype
, decl
);
514 rval
= build_up_reference (reftype
, rval
, flags
, decl
, complain
);
519 /* If we found a way to convert earlier, then use it. */
523 if (complain
& tf_error
)
524 error_at (loc
, "cannot convert type %qH to type %qI", intype
, reftype
);
526 return error_mark_node
;
529 /* We are using a reference VAL for its value. Bash that reference all the
530 way down to its lowest form. */
533 convert_from_reference (tree val
)
536 && TREE_CODE (TREE_TYPE (val
)) == REFERENCE_TYPE
)
538 tree t
= TREE_TYPE (TREE_TYPE (val
));
539 tree ref
= build1 (INDIRECT_REF
, t
, val
);
542 /* We *must* set TREE_READONLY when dereferencing a pointer to const,
543 so that we get the proper error message if the result is used
544 to assign to. Also, &* is supposed to be a no-op. */
545 TREE_READONLY (ref
) = CP_TYPE_CONST_P (t
);
546 TREE_THIS_VOLATILE (ref
) = CP_TYPE_VOLATILE_P (t
);
547 TREE_SIDE_EFFECTS (ref
)
548 = (TREE_THIS_VOLATILE (ref
) || TREE_SIDE_EFFECTS (val
));
555 /* Really perform an lvalue-to-rvalue conversion, including copying an
556 argument of class type into a temporary. */
559 force_rvalue (tree expr
, tsubst_flags_t complain
)
561 tree type
= TREE_TYPE (expr
);
562 if (MAYBE_CLASS_TYPE_P (type
) && TREE_CODE (expr
) != TARGET_EXPR
)
564 vec
<tree
, va_gc
> *args
= make_tree_vector_single (expr
);
565 expr
= build_special_member_call (NULL_TREE
, complete_ctor_identifier
,
566 &args
, type
, LOOKUP_NORMAL
, complain
);
567 release_tree_vector (args
);
568 expr
= build_cplus_new (type
, expr
, complain
);
571 expr
= decay_conversion (expr
, complain
);
577 /* If EXPR and ORIG are INTEGER_CSTs, return a version of EXPR that has
578 TREE_OVERFLOW set only if it is set in ORIG. Otherwise, return EXPR
582 ignore_overflows (tree expr
, tree orig
)
584 if (TREE_CODE (expr
) == INTEGER_CST
585 && TREE_CODE (orig
) == INTEGER_CST
586 && TREE_OVERFLOW (expr
) != TREE_OVERFLOW (orig
))
588 gcc_assert (!TREE_OVERFLOW (orig
));
589 /* Ensure constant sharing. */
590 expr
= wide_int_to_tree (TREE_TYPE (expr
), wi::to_wide (expr
));
595 /* Fold away simple conversions, but make sure TREE_OVERFLOW is set
599 cp_fold_convert (tree type
, tree expr
)
602 if (TREE_TYPE (expr
) == type
)
604 else if (TREE_CODE (expr
) == PTRMEM_CST
)
606 /* Avoid wrapping a PTRMEM_CST in NOP_EXPR. */
607 conv
= copy_node (expr
);
608 TREE_TYPE (conv
) = type
;
612 conv
= fold_convert (type
, expr
);
613 conv
= ignore_overflows (conv
, expr
);
618 /* C++ conversions, preference to static cast conversions. */
621 cp_convert (tree type
, tree expr
, tsubst_flags_t complain
)
623 return ocp_convert (type
, expr
, CONV_OLD_CONVERT
, LOOKUP_NORMAL
, complain
);
626 /* C++ equivalent of convert_and_check but using cp_convert as the
629 Convert EXPR to TYPE, warning about conversion problems with constants.
630 Invoke this function on every expression that is converted implicitly,
631 i.e. because of language rules and not because of an explicit cast. */
634 cp_convert_and_check (tree type
, tree expr
, tsubst_flags_t complain
)
638 if (TREE_TYPE (expr
) == type
)
640 if (expr
== error_mark_node
)
642 result
= cp_convert (type
, expr
, complain
);
644 if ((complain
& tf_warning
)
645 && c_inhibit_evaluation_warnings
== 0)
647 tree folded
= cp_fully_fold (expr
);
650 folded_result
= result
;
653 /* Avoid bogus -Wparentheses warnings. */
654 warning_sentinel
w (warn_parentheses
);
655 warning_sentinel
c (warn_int_in_bool_context
);
656 folded_result
= cp_convert (type
, folded
, tf_none
);
658 folded_result
= fold_simple (folded_result
);
659 if (!TREE_OVERFLOW_P (folded
)
660 && folded_result
!= error_mark_node
)
661 warnings_for_convert_and_check (EXPR_LOC_OR_LOC (expr
, input_location
),
662 type
, folded
, folded_result
);
670 FLAGS indicates how we should behave. */
673 ocp_convert (tree type
, tree expr
, int convtype
, int flags
,
674 tsubst_flags_t complain
)
677 enum tree_code code
= TREE_CODE (type
);
678 const char *invalid_conv_diag
;
680 location_t loc
= EXPR_LOC_OR_LOC (expr
, input_location
);
681 bool dofold
= (convtype
& CONV_FOLD
);
683 if (error_operand_p (e
) || type
== error_mark_node
)
684 return error_mark_node
;
686 complete_type (type
);
687 complete_type (TREE_TYPE (expr
));
689 if ((invalid_conv_diag
690 = targetm
.invalid_conversion (TREE_TYPE (expr
), type
)))
692 if (complain
& tf_error
)
693 error (invalid_conv_diag
);
694 return error_mark_node
;
697 /* FIXME remove when moving to c_fully_fold model. */
698 if (!CLASS_TYPE_P (type
))
700 e
= mark_rvalue_use (e
);
701 e
= scalar_constant_value (e
);
703 if (error_operand_p (e
))
704 return error_mark_node
;
706 if (MAYBE_CLASS_TYPE_P (type
) && (convtype
& CONV_FORCE_TEMP
))
707 /* We need a new temporary; don't take this shortcut. */;
708 else if (same_type_ignoring_top_level_qualifiers_p (type
, TREE_TYPE (e
)))
710 if (same_type_p (type
, TREE_TYPE (e
)))
711 /* The call to fold will not always remove the NOP_EXPR as
712 might be expected, since if one of the types is a typedef;
713 the comparison in fold is just equality of pointers, not a
714 call to comptypes. We don't call fold in this case because
715 that can result in infinite recursion; fold will call
716 convert, which will call ocp_convert, etc. */
718 /* For complex data types, we need to perform componentwise
720 else if (TREE_CODE (type
) == COMPLEX_TYPE
)
721 return convert_to_complex_maybe_fold (type
, e
, dofold
);
722 else if (VECTOR_TYPE_P (type
))
723 return convert_to_vector (type
, e
);
724 else if (TREE_CODE (e
) == TARGET_EXPR
)
726 /* Don't build a NOP_EXPR of class type. Instead, change the
727 type of the temporary. */
728 TREE_TYPE (e
) = TREE_TYPE (TARGET_EXPR_SLOT (e
)) = type
;
733 /* We shouldn't be treating objects of ADDRESSABLE type as
735 gcc_assert (!TREE_ADDRESSABLE (type
));
736 return build_nop (type
, e
);
740 e1
= targetm
.convert_to_type (type
, e
);
744 if (code
== VOID_TYPE
&& (convtype
& CONV_STATIC
))
746 e
= convert_to_void (e
, ICV_CAST
, complain
);
750 if (INTEGRAL_CODE_P (code
))
752 tree intype
= TREE_TYPE (e
);
755 if (TREE_CODE (type
) == ENUMERAL_TYPE
)
757 /* enum = enum, enum = int, enum = float, (enum)pointer are all
759 if (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype
)
760 || TREE_CODE (intype
) == REAL_TYPE
)
761 && ! (convtype
& CONV_STATIC
))
762 || TYPE_PTR_P (intype
))
764 if (complain
& tf_error
)
765 permerror (loc
, "conversion from %q#T to %q#T", intype
, type
);
767 return error_mark_node
;
770 /* [expr.static.cast]
772 8. A value of integral or enumeration type can be explicitly
773 converted to an enumeration type. The value is unchanged if
774 the original value is within the range of the enumeration
775 values. Otherwise, the resulting enumeration value is
777 if ((complain
& tf_warning
)
778 && TREE_CODE (e
) == INTEGER_CST
779 && ENUM_UNDERLYING_TYPE (type
)
780 && !int_fits_type_p (e
, ENUM_UNDERLYING_TYPE (type
)))
781 warning_at (loc
, OPT_Wconversion
,
782 "the result of the conversion is unspecified because "
783 "%qE is outside the range of type %qT",
786 if (MAYBE_CLASS_TYPE_P (intype
))
789 rval
= build_type_conversion (type
, e
);
792 if (complain
& tf_error
)
793 error_at (loc
, "%q#T used where a %qT was expected", intype
, type
);
794 return error_mark_node
;
796 if (code
== BOOLEAN_TYPE
)
798 if (VOID_TYPE_P (intype
))
800 if (complain
& tf_error
)
802 "could not convert %qE from %<void%> to %<bool%>",
804 return error_mark_node
;
807 /* We can't implicitly convert a scoped enum to bool, so convert
808 to the underlying type first. */
809 if (SCOPED_ENUM_P (intype
) && (convtype
& CONV_STATIC
))
810 e
= build_nop (ENUM_UNDERLYING_TYPE (intype
), e
);
811 if (complain
& tf_warning
)
812 return cp_truthvalue_conversion (e
);
815 /* Prevent bogus -Wint-in-bool-context warnings coming
816 from c_common_truthvalue_conversion down the line. */
817 warning_sentinel
w (warn_int_in_bool_context
);
818 return cp_truthvalue_conversion (e
);
822 converted
= convert_to_integer_maybe_fold (type
, e
, dofold
);
824 /* Ignore any integer overflow caused by the conversion. */
825 return ignore_overflows (converted
, e
);
827 if (NULLPTR_TYPE_P (type
) && e
&& null_ptr_cst_p (e
))
829 if (complain
& tf_warning
)
830 maybe_warn_zero_as_null_pointer_constant (e
, loc
);
833 if (POINTER_TYPE_P (type
) || TYPE_PTRMEM_P (type
))
834 return cp_convert_to_pointer (type
, e
, dofold
, complain
);
835 if (code
== VECTOR_TYPE
)
837 tree in_vtype
= TREE_TYPE (e
);
838 if (MAYBE_CLASS_TYPE_P (in_vtype
))
841 ret_val
= build_type_conversion (type
, e
);
844 if (complain
& tf_error
)
845 error_at (loc
, "%q#T used where a %qT was expected",
847 return error_mark_node
;
849 return convert_to_vector (type
, e
);
851 if (code
== REAL_TYPE
|| code
== COMPLEX_TYPE
)
853 if (MAYBE_CLASS_TYPE_P (TREE_TYPE (e
)))
856 rval
= build_type_conversion (type
, e
);
859 else if (complain
& tf_error
)
861 "%q#T used where a floating point value was expected",
864 if (code
== REAL_TYPE
)
865 return convert_to_real_maybe_fold (type
, e
, dofold
);
866 else if (code
== COMPLEX_TYPE
)
867 return convert_to_complex_maybe_fold (type
, e
, dofold
);
870 /* New C++ semantics: since assignment is now based on
871 memberwise copying, if the rhs type is derived from the
872 lhs type, then we may still do a conversion. */
873 if (RECORD_OR_UNION_CODE_P (code
))
875 tree dtype
= TREE_TYPE (e
);
876 tree ctor
= NULL_TREE
;
878 dtype
= TYPE_MAIN_VARIANT (dtype
);
880 /* Conversion between aggregate types. New C++ semantics allow
881 objects of derived type to be cast to objects of base type.
882 Old semantics only allowed this between pointers.
884 There may be some ambiguity between using a constructor
885 vs. using a type conversion operator when both apply. */
889 if (abstract_virtuals_error_sfinae (NULL_TREE
, type
, complain
))
890 return error_mark_node
;
892 if (BRACE_ENCLOSED_INITIALIZER_P (ctor
))
893 ctor
= perform_implicit_conversion (type
, ctor
, complain
);
894 else if ((flags
& LOOKUP_ONLYCONVERTING
)
895 && ! (CLASS_TYPE_P (dtype
) && DERIVED_FROM_P (type
, dtype
)))
896 /* For copy-initialization, first we create a temp of the proper type
897 with a user-defined conversion sequence, then we direct-initialize
898 the target with the temp (see [dcl.init]). */
899 ctor
= build_user_type_conversion (type
, ctor
, flags
, complain
);
902 vec
<tree
, va_gc
> *ctor_vec
= make_tree_vector_single (ctor
);
903 ctor
= build_special_member_call (NULL_TREE
,
904 complete_ctor_identifier
,
906 type
, flags
, complain
);
907 release_tree_vector (ctor_vec
);
910 return build_cplus_new (type
, ctor
, complain
);
913 if (complain
& tf_error
)
915 /* If the conversion failed and expr was an invalid use of pointer to
916 member function, try to report a meaningful error. */
917 if (invalid_nonstatic_memfn_p (loc
, expr
, complain
))
918 /* We displayed the error message. */;
920 error_at (loc
, "conversion from %qH to non-scalar type %qI requested",
921 TREE_TYPE (expr
), type
);
923 return error_mark_node
;
926 /* If CALL is a call, return the callee; otherwise null. */
929 cp_get_callee (tree call
)
931 if (call
== NULL_TREE
)
933 else if (TREE_CODE (call
) == CALL_EXPR
)
934 return CALL_EXPR_FN (call
);
935 else if (TREE_CODE (call
) == AGGR_INIT_EXPR
)
936 return AGGR_INIT_EXPR_FN (call
);
940 /* FN is the callee of a CALL_EXPR or AGGR_INIT_EXPR; return the FUNCTION_DECL
944 cp_get_fndecl_from_callee (tree fn
)
948 if (TREE_CODE (fn
) == FUNCTION_DECL
)
950 tree type
= TREE_TYPE (fn
);
951 if (type
== unknown_type_node
)
953 gcc_assert (POINTER_TYPE_P (type
));
954 fn
= maybe_constant_init (fn
);
956 if (TREE_CODE (fn
) == ADDR_EXPR
)
958 fn
= TREE_OPERAND (fn
, 0);
959 if (TREE_CODE (fn
) == FUNCTION_DECL
)
965 /* Like get_callee_fndecl, but handles AGGR_INIT_EXPR as well and uses the
966 constexpr machinery. */
969 cp_get_callee_fndecl (tree call
)
971 return cp_get_fndecl_from_callee (cp_get_callee (call
));
974 /* Subroutine of convert_to_void. Warn if we're discarding something with
975 attribute [[nodiscard]]. */
978 maybe_warn_nodiscard (tree expr
, impl_conv_void implicit
)
981 if (TREE_CODE (expr
) == TARGET_EXPR
)
982 call
= TARGET_EXPR_INITIAL (expr
);
983 location_t loc
= EXPR_LOC_OR_LOC (call
, input_location
);
984 tree callee
= cp_get_callee (call
);
988 tree type
= TREE_TYPE (callee
);
989 if (TYPE_PTRMEMFUNC_P (type
))
990 type
= TYPE_PTRMEMFUNC_FN_TYPE (type
);
991 if (POINTER_TYPE_P (type
))
992 type
= TREE_TYPE (type
);
994 tree rettype
= TREE_TYPE (type
);
995 tree fn
= cp_get_fndecl_from_callee (callee
);
996 if (implicit
!= ICV_CAST
&& fn
997 && lookup_attribute ("nodiscard", DECL_ATTRIBUTES (fn
)))
999 if (warning_at (loc
, OPT_Wunused_result
,
1000 "ignoring return value of %qD, "
1001 "declared with attribute nodiscard", fn
))
1002 inform (DECL_SOURCE_LOCATION (fn
), "declared here");
1004 else if (implicit
!= ICV_CAST
1005 && lookup_attribute ("nodiscard", TYPE_ATTRIBUTES (rettype
)))
1007 if (warning_at (loc
, OPT_Wunused_result
,
1008 "ignoring returned value of type %qT, "
1009 "declared with attribute nodiscard", rettype
))
1012 inform (DECL_SOURCE_LOCATION (fn
),
1013 "in call to %qD, declared here", fn
);
1014 inform (DECL_SOURCE_LOCATION (TYPE_NAME (rettype
)),
1015 "%qT declared here", rettype
);
1018 else if (TREE_CODE (expr
) == TARGET_EXPR
1019 && lookup_attribute ("warn_unused_result", TYPE_ATTRIBUTES (type
)))
1021 /* The TARGET_EXPR confuses do_warn_unused_result into thinking that the
1022 result is used, so handle that case here. */
1025 if (warning_at (loc
, OPT_Wunused_result
,
1026 "ignoring return value of %qD, "
1027 "declared with attribute warn_unused_result",
1029 inform (DECL_SOURCE_LOCATION (fn
), "declared here");
1032 warning_at (loc
, OPT_Wunused_result
,
1033 "ignoring return value of function "
1034 "declared with attribute warn_unused_result");
1038 /* When an expression is used in a void context, its value is discarded and
1039 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
1040 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
1041 in a void context. The C++ standard does not define what an `access' to an
1042 object is, but there is reason to believe that it is the lvalue to rvalue
1043 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
1044 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
1045 indicates that volatile semantics should be the same between C and C++
1046 where ever possible. C leaves it implementation defined as to what
1047 constitutes an access to a volatile. So, we interpret `*vp' as a read of
1048 the volatile object `vp' points to, unless that is an incomplete type. For
1049 volatile references we do not do this interpretation, because that would
1050 make it impossible to ignore the reference return value from functions. We
1051 issue warnings in the confusing cases.
1053 The IMPLICIT is ICV_CAST when the user is explicitly converting an expression
1054 to void via a cast. If an expression is being implicitly converted, IMPLICIT
1055 indicates the context of the implicit conversion. */
1058 convert_to_void (tree expr
, impl_conv_void implicit
, tsubst_flags_t complain
)
1060 location_t loc
= EXPR_LOC_OR_LOC (expr
, input_location
);
1062 if (expr
== error_mark_node
1063 || TREE_TYPE (expr
) == error_mark_node
)
1064 return error_mark_node
;
1066 expr
= maybe_undo_parenthesized_ref (expr
);
1068 expr
= mark_discarded_use (expr
);
1069 if (implicit
== ICV_CAST
)
1070 /* An explicit cast to void avoids all -Wunused-but-set* warnings. */
1071 mark_exp_read (expr
);
1073 if (!TREE_TYPE (expr
))
1075 if (invalid_nonstatic_memfn_p (loc
, expr
, complain
))
1076 return error_mark_node
;
1077 if (TREE_CODE (expr
) == PSEUDO_DTOR_EXPR
)
1079 if (complain
& tf_error
)
1080 error_at (loc
, "pseudo-destructor is not called");
1081 return error_mark_node
;
1083 if (VOID_TYPE_P (TREE_TYPE (expr
)))
1085 switch (TREE_CODE (expr
))
1089 /* The two parts of a cond expr might be separate lvalues. */
1090 tree op1
= TREE_OPERAND (expr
,1);
1091 tree op2
= TREE_OPERAND (expr
,2);
1092 bool side_effects
= ((op1
&& TREE_SIDE_EFFECTS (op1
))
1093 || TREE_SIDE_EFFECTS (op2
));
1094 tree new_op1
, new_op2
;
1095 new_op1
= NULL_TREE
;
1096 if (implicit
!= ICV_CAST
&& !side_effects
)
1099 new_op1
= convert_to_void (op1
, ICV_SECOND_OF_COND
, complain
);
1100 new_op2
= convert_to_void (op2
, ICV_THIRD_OF_COND
, complain
);
1105 new_op1
= convert_to_void (op1
, ICV_CAST
, complain
);
1106 new_op2
= convert_to_void (op2
, ICV_CAST
, complain
);
1109 expr
= build3 (COND_EXPR
, TREE_TYPE (new_op2
),
1110 TREE_OPERAND (expr
, 0), new_op1
, new_op2
);
1116 /* The second part of a compound expr contains the value. */
1117 tree op1
= TREE_OPERAND (expr
,1);
1119 if (implicit
!= ICV_CAST
&& !TREE_NO_WARNING (expr
))
1120 new_op1
= convert_to_void (op1
, ICV_RIGHT_OF_COMMA
, complain
);
1122 new_op1
= convert_to_void (op1
, ICV_CAST
, complain
);
1126 tree t
= build2 (COMPOUND_EXPR
, TREE_TYPE (new_op1
),
1127 TREE_OPERAND (expr
, 0), new_op1
);
1134 case NON_LVALUE_EXPR
:
1136 /* These have already decayed to rvalue. */
1139 case CALL_EXPR
: /* We have a special meaning for volatile void fn(). */
1140 maybe_warn_nodiscard (expr
, implicit
);
1145 tree type
= TREE_TYPE (expr
);
1146 int is_reference
= TREE_CODE (TREE_TYPE (TREE_OPERAND (expr
, 0)))
1148 int is_volatile
= TYPE_VOLATILE (type
);
1149 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
1151 /* Can't load the value if we don't know the type. */
1152 if (is_volatile
&& !is_complete
)
1154 if (complain
& tf_warning
)
1158 warning_at (loc
, 0, "conversion to void will not access "
1159 "object of incomplete type %qT", type
);
1161 case ICV_SECOND_OF_COND
:
1162 warning_at (loc
, 0, "indirection will not access object of "
1163 "incomplete type %qT in second operand "
1164 "of conditional expression", type
);
1166 case ICV_THIRD_OF_COND
:
1167 warning_at (loc
, 0, "indirection will not access object of "
1168 "incomplete type %qT in third operand "
1169 "of conditional expression", type
);
1171 case ICV_RIGHT_OF_COMMA
:
1172 warning_at (loc
, 0, "indirection will not access object of "
1173 "incomplete type %qT in right operand of "
1174 "comma operator", type
);
1176 case ICV_LEFT_OF_COMMA
:
1177 warning_at (loc
, 0, "indirection will not access object of "
1178 "incomplete type %qT in left operand of "
1179 "comma operator", type
);
1182 warning_at (loc
, 0, "indirection will not access object of "
1183 "incomplete type %qT in statement", type
);
1185 case ICV_THIRD_IN_FOR
:
1186 warning_at (loc
, 0, "indirection will not access object of "
1187 "incomplete type %qT in for increment "
1188 "expression", type
);
1194 /* Don't load the value if this is an implicit dereference, or if
1195 the type needs to be handled by ctors/dtors. */
1196 else if (is_volatile
&& is_reference
)
1198 if (complain
& tf_warning
)
1202 warning_at (loc
, 0, "conversion to void will not access "
1203 "object of type %qT", type
);
1205 case ICV_SECOND_OF_COND
:
1206 warning_at (loc
, 0, "implicit dereference will not access "
1207 "object of type %qT in second operand of "
1208 "conditional expression", type
);
1210 case ICV_THIRD_OF_COND
:
1211 warning_at (loc
, 0, "implicit dereference will not access "
1212 "object of type %qT in third operand of "
1213 "conditional expression", type
);
1215 case ICV_RIGHT_OF_COMMA
:
1216 warning_at (loc
, 0, "implicit dereference will not access "
1217 "object of type %qT in right operand of "
1218 "comma operator", type
);
1220 case ICV_LEFT_OF_COMMA
:
1221 warning_at (loc
, 0, "implicit dereference will not access "
1222 "object of type %qT in left operand of comma "
1226 warning_at (loc
, 0, "implicit dereference will not access "
1227 "object of type %qT in statement", type
);
1229 case ICV_THIRD_IN_FOR
:
1230 warning_at (loc
, 0, "implicit dereference will not access "
1231 "object of type %qT in for increment expression",
1238 else if (is_volatile
&& TREE_ADDRESSABLE (type
))
1240 if (complain
& tf_warning
)
1244 warning_at (loc
, 0, "conversion to void will not access "
1245 "object of non-trivially-copyable type %qT",
1248 case ICV_SECOND_OF_COND
:
1249 warning_at (loc
, 0, "indirection will not access object of "
1250 "non-trivially-copyable type %qT in second "
1251 "operand of conditional expression", type
);
1253 case ICV_THIRD_OF_COND
:
1254 warning_at (loc
, 0, "indirection will not access object of "
1255 "non-trivially-copyable type %qT in third "
1256 "operand of conditional expression", type
);
1258 case ICV_RIGHT_OF_COMMA
:
1259 warning_at (loc
, 0, "indirection will not access object of "
1260 "non-trivially-copyable type %qT in right "
1261 "operand of comma operator", type
);
1263 case ICV_LEFT_OF_COMMA
:
1264 warning_at (loc
, 0, "indirection will not access object of "
1265 "non-trivially-copyable type %qT in left "
1266 "operand of comma operator", type
);
1269 warning_at (loc
, 0, "indirection will not access object of "
1270 "non-trivially-copyable type %qT in statement",
1273 case ICV_THIRD_IN_FOR
:
1274 warning_at (loc
, 0, "indirection will not access object of "
1275 "non-trivially-copyable type %qT in for "
1276 "increment expression", type
);
1282 if (is_reference
|| !is_volatile
|| !is_complete
|| TREE_ADDRESSABLE (type
))
1284 /* Emit a warning (if enabled) when the "effect-less" INDIRECT_REF
1285 operation is stripped off. Note that we don't warn about
1286 - an expression with TREE_NO_WARNING set. (For an example of
1287 such expressions, see build_over_call in call.c.)
1288 - automatic dereferencing of references, since the user cannot
1289 control it. (See also warn_if_unused_value() in c-common.c.) */
1290 if (warn_unused_value
1291 && implicit
!= ICV_CAST
1292 && (complain
& tf_warning
)
1293 && !TREE_NO_WARNING (expr
)
1295 warning_at (loc
, OPT_Wunused_value
, "value computed is not used");
1296 expr
= TREE_OPERAND (expr
, 0);
1297 if (TREE_CODE (expr
) == CALL_EXPR
)
1298 maybe_warn_nodiscard (expr
, implicit
);
1306 /* External variables might be incomplete. */
1307 tree type
= TREE_TYPE (expr
);
1308 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
1310 if (TYPE_VOLATILE (type
) && !is_complete
&& (complain
& tf_warning
))
1314 warning_at (loc
, 0, "conversion to void will not access "
1315 "object %qE of incomplete type %qT", expr
, type
);
1317 case ICV_SECOND_OF_COND
:
1318 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1319 "not be accessed in second operand of "
1320 "conditional expression", expr
, type
);
1322 case ICV_THIRD_OF_COND
:
1323 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1324 "not be accessed in third operand of "
1325 "conditional expression", expr
, type
);
1327 case ICV_RIGHT_OF_COMMA
:
1328 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1329 "not be accessed in right operand of comma operator",
1332 case ICV_LEFT_OF_COMMA
:
1333 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1334 "not be accessed in left operand of comma operator",
1338 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1339 "not be accessed in statement", expr
, type
);
1341 case ICV_THIRD_IN_FOR
:
1342 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1343 "not be accessed in for increment expression",
1354 /* Don't bother with the temporary object returned from a function if
1355 we don't use it, don't need to destroy it, and won't abort in
1356 assign_temp. We'll still
1357 allocate space for it in expand_call or declare_return_variable,
1358 but we don't need to track it through all the tree phases. */
1359 if (TARGET_EXPR_IMPLICIT_P (expr
)
1360 && !TREE_ADDRESSABLE (TREE_TYPE (expr
)))
1362 tree init
= TARGET_EXPR_INITIAL (expr
);
1363 if (TREE_CODE (init
) == AGGR_INIT_EXPR
1364 && !AGGR_INIT_VIA_CTOR_P (init
))
1366 tree fn
= AGGR_INIT_EXPR_FN (init
);
1367 expr
= build_call_array_loc (input_location
,
1368 TREE_TYPE (TREE_TYPE
1371 aggr_init_expr_nargs (init
),
1372 AGGR_INIT_EXPR_ARGP (init
));
1375 maybe_warn_nodiscard (expr
, implicit
);
1380 expr
= resolve_nondeduced_context (expr
, complain
);
1384 if (TREE_CODE (probe
) == ADDR_EXPR
)
1385 probe
= TREE_OPERAND (expr
, 0);
1386 if (type_unknown_p (probe
))
1388 /* [over.over] enumerates the places where we can take the address
1389 of an overloaded function, and this is not one of them. */
1390 if (complain
& tf_error
)
1394 error_at (loc
, "conversion to void "
1395 "cannot resolve address of overloaded function");
1397 case ICV_SECOND_OF_COND
:
1398 error_at (loc
, "second operand of conditional expression "
1399 "cannot resolve address of overloaded function");
1401 case ICV_THIRD_OF_COND
:
1402 error_at (loc
, "third operand of conditional expression "
1403 "cannot resolve address of overloaded function");
1405 case ICV_RIGHT_OF_COMMA
:
1406 error_at (loc
, "right operand of comma operator "
1407 "cannot resolve address of overloaded function");
1409 case ICV_LEFT_OF_COMMA
:
1410 error_at (loc
, "left operand of comma operator "
1411 "cannot resolve address of overloaded function");
1414 error_at (loc
, "statement "
1415 "cannot resolve address of overloaded function");
1417 case ICV_THIRD_IN_FOR
:
1418 error_at (loc
, "for increment expression "
1419 "cannot resolve address of overloaded function");
1423 return error_mark_node
;
1426 else if (implicit
!= ICV_CAST
&& probe
== expr
&& is_overloaded_fn (probe
))
1428 /* Only warn when there is no &. */
1429 if (complain
& tf_warning
)
1432 case ICV_SECOND_OF_COND
:
1433 warning_at (loc
, OPT_Waddress
,
1434 "second operand of conditional expression "
1435 "is a reference, not call, to function %qE", expr
);
1437 case ICV_THIRD_OF_COND
:
1438 warning_at (loc
, OPT_Waddress
,
1439 "third operand of conditional expression "
1440 "is a reference, not call, to function %qE", expr
);
1442 case ICV_RIGHT_OF_COMMA
:
1443 warning_at (loc
, OPT_Waddress
,
1444 "right operand of comma operator "
1445 "is a reference, not call, to function %qE", expr
);
1447 case ICV_LEFT_OF_COMMA
:
1448 warning_at (loc
, OPT_Waddress
,
1449 "left operand of comma operator "
1450 "is a reference, not call, to function %qE", expr
);
1453 warning_at (loc
, OPT_Waddress
,
1454 "statement is a reference, not call, to function %qE",
1457 case ICV_THIRD_IN_FOR
:
1458 warning_at (loc
, OPT_Waddress
,
1459 "for increment expression "
1460 "is a reference, not call, to function %qE", expr
);
1466 if (TREE_CODE (expr
) == COMPONENT_REF
)
1467 expr
= TREE_OPERAND (expr
, 0);
1471 if (expr
!= error_mark_node
&& !VOID_TYPE_P (TREE_TYPE (expr
)))
1473 if (implicit
!= ICV_CAST
1474 && warn_unused_value
1475 && !TREE_NO_WARNING (expr
)
1476 && !processing_template_decl
)
1478 /* The middle end does not warn about expressions that have
1479 been explicitly cast to void, so we must do so here. */
1480 if (!TREE_SIDE_EFFECTS (expr
)) {
1481 if (complain
& tf_warning
)
1484 case ICV_SECOND_OF_COND
:
1485 warning_at (loc
, OPT_Wunused_value
,
1486 "second operand of conditional expression "
1489 case ICV_THIRD_OF_COND
:
1490 warning_at (loc
, OPT_Wunused_value
,
1491 "third operand of conditional expression "
1494 case ICV_RIGHT_OF_COMMA
:
1495 warning_at (loc
, OPT_Wunused_value
,
1496 "right operand of comma operator has no effect");
1498 case ICV_LEFT_OF_COMMA
:
1499 warning_at (loc
, OPT_Wunused_value
,
1500 "left operand of comma operator has no effect");
1503 warning_at (loc
, OPT_Wunused_value
,
1504 "statement has no effect");
1506 case ICV_THIRD_IN_FOR
:
1507 warning_at (loc
, OPT_Wunused_value
,
1508 "for increment expression has no effect");
1517 enum tree_code code
;
1518 enum tree_code_class tclass
;
1521 /* We might like to warn about (say) "(int) f()", as the
1522 cast has no effect, but the compiler itself will
1523 generate implicit conversions under some
1524 circumstances. (For example a block copy will be
1525 turned into a call to "__builtin_memcpy", with a
1526 conversion of the return value to an appropriate
1527 type.) So, to avoid false positives, we strip
1528 conversions. Do not use STRIP_NOPs because it will
1529 not strip conversions to "void", as that is not a
1530 mode-preserving conversion. */
1531 while (TREE_CODE (e
) == NOP_EXPR
)
1532 e
= TREE_OPERAND (e
, 0);
1534 code
= TREE_CODE (e
);
1535 tclass
= TREE_CODE_CLASS (code
);
1536 if ((tclass
== tcc_comparison
1537 || tclass
== tcc_unary
1538 || (tclass
== tcc_binary
1539 && !(code
== MODIFY_EXPR
1540 || code
== INIT_EXPR
1541 || code
== PREDECREMENT_EXPR
1542 || code
== PREINCREMENT_EXPR
1543 || code
== POSTDECREMENT_EXPR
1544 || code
== POSTINCREMENT_EXPR
))
1545 || code
== VEC_PERM_EXPR
1546 || code
== VEC_COND_EXPR
)
1547 && (complain
& tf_warning
))
1548 warning_at (loc
, OPT_Wunused_value
, "value computed is not used");
1551 expr
= build1 (CONVERT_EXPR
, void_type_node
, expr
);
1553 if (! TREE_SIDE_EFFECTS (expr
))
1558 /* Create an expression whose value is that of EXPR,
1559 converted to type TYPE. The TREE_TYPE of the value
1560 is always TYPE. This function implements all reasonable
1561 conversions; callers should filter out those that are
1562 not permitted by the language being compiled.
1564 Most of this routine is from build_reinterpret_cast.
1566 The back end cannot call cp_convert (what was convert) because
1567 conversions to/from basetypes may involve memory references
1568 (vbases) and adding or subtracting small values (multiple
1569 inheritance), but it calls convert from the constant folding code
1570 on subtrees of already built trees after it has ripped them apart.
1572 Also, if we ever support range variables, we'll probably also have to
1573 do a little bit more work. */
1576 convert (tree type
, tree expr
)
1580 if (type
== error_mark_node
|| expr
== error_mark_node
)
1581 return error_mark_node
;
1583 intype
= TREE_TYPE (expr
);
1585 if (POINTER_TYPE_P (type
) && POINTER_TYPE_P (intype
))
1586 return build_nop (type
, expr
);
1588 return ocp_convert (type
, expr
, CONV_BACKEND_CONVERT
,
1589 LOOKUP_NORMAL
|LOOKUP_NO_CONVERSION
,
1590 tf_warning_or_error
);
1593 /* Like cp_convert, except permit conversions to take place which
1594 are not normally allowed due to access restrictions
1595 (such as conversion from sub-type to private super-type). */
1598 convert_force (tree type
, tree expr
, int convtype
, tsubst_flags_t complain
)
1601 enum tree_code code
= TREE_CODE (type
);
1603 if (code
== REFERENCE_TYPE
)
1604 return convert_to_reference (type
, e
, CONV_C_CAST
, 0,
1605 NULL_TREE
, complain
);
1607 if (code
== POINTER_TYPE
)
1608 return convert_to_pointer_force (type
, e
, complain
);
1610 /* From typeck.c convert_for_assignment */
1611 if (((TYPE_PTR_P (TREE_TYPE (e
)) && TREE_CODE (e
) == ADDR_EXPR
1612 && TREE_CODE (TREE_TYPE (TREE_TYPE (e
))) == METHOD_TYPE
)
1613 || integer_zerop (e
)
1614 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e
)))
1615 && TYPE_PTRMEMFUNC_P (type
))
1616 /* compatible pointer to member functions. */
1617 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), e
, 1,
1618 /*c_cast_p=*/1, complain
);
1620 return ocp_convert (type
, e
, CONV_C_CAST
|convtype
, LOOKUP_NORMAL
, complain
);
1623 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1624 exists, return the attempted conversion. This may
1625 return ERROR_MARK_NODE if the conversion is not
1626 allowed (references private members, etc).
1627 If no conversion exists, NULL_TREE is returned.
1629 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1630 object parameter, or by the second standard conversion sequence if
1631 that doesn't do it. This will probably wait for an overloading rewrite.
1635 build_type_conversion (tree xtype
, tree expr
)
1637 /* C++: check to see if we can convert this aggregate type
1638 into the required type. */
1639 return build_user_type_conversion (xtype
, expr
, LOOKUP_NORMAL
,
1640 tf_warning_or_error
);
1643 /* Convert the given EXPR to one of a group of types suitable for use in an
1644 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1645 which indicates which types are suitable. If COMPLAIN is true, complain
1646 about ambiguity; otherwise, the caller will deal with it. */
1649 build_expr_type_conversion (int desires
, tree expr
, bool complain
)
1651 tree basetype
= TREE_TYPE (expr
);
1652 tree conv
= NULL_TREE
;
1653 tree winner
= NULL_TREE
;
1655 if (null_node_p (expr
)
1656 && (desires
& WANT_INT
)
1657 && !(desires
& WANT_NULL
))
1659 source_location loc
=
1660 expansion_point_location_if_in_system_header (input_location
);
1662 warning_at (loc
, OPT_Wconversion_null
,
1663 "converting NULL to non-pointer type");
1666 if (basetype
== error_mark_node
)
1667 return error_mark_node
;
1669 if (! MAYBE_CLASS_TYPE_P (basetype
))
1670 switch (TREE_CODE (basetype
))
1673 if ((desires
& WANT_NULL
) && null_ptr_cst_p (expr
))
1678 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1680 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1682 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1684 return (desires
& WANT_POINTER
) ? expr
: NULL_TREE
;
1688 return (desires
& WANT_POINTER
) ? decay_conversion (expr
,
1689 tf_warning_or_error
)
1694 if ((desires
& WANT_VECTOR_OR_COMPLEX
) == 0)
1696 switch (TREE_CODE (TREE_TYPE (basetype
)))
1700 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1702 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1704 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1713 /* The code for conversions from class type is currently only used for
1714 delete expressions. Other expressions are handled by build_new_op. */
1715 if (!complete_type_or_maybe_complain (basetype
, expr
, complain
))
1716 return error_mark_node
;
1717 if (!TYPE_HAS_CONVERSION (basetype
))
1720 for (conv
= lookup_conversions (basetype
); conv
; conv
= TREE_CHAIN (conv
))
1724 tree cand
= TREE_VALUE (conv
);
1725 cand
= OVL_FIRST (cand
);
1727 if (winner
&& winner
== cand
)
1730 if (DECL_NONCONVERTING_P (cand
))
1733 candidate
= non_reference (TREE_TYPE (TREE_TYPE (cand
)));
1735 switch (TREE_CODE (candidate
))
1739 win
= (desires
& WANT_INT
); break;
1741 win
= (desires
& WANT_ENUM
); break;
1743 win
= (desires
& WANT_FLOAT
); break;
1745 win
= (desires
& WANT_POINTER
); break;
1749 if ((desires
& WANT_VECTOR_OR_COMPLEX
) == 0)
1751 switch (TREE_CODE (TREE_TYPE (candidate
)))
1755 win
= (desires
& WANT_INT
); break;
1757 win
= (desires
& WANT_ENUM
); break;
1759 win
= (desires
& WANT_FLOAT
); break;
1766 /* A wildcard could be instantiated to match any desired
1767 type, but we can't deduce the template argument. */
1768 if (WILDCARD_TYPE_P (candidate
))
1775 if (TREE_CODE (cand
) == TEMPLATE_DECL
)
1778 error ("default type conversion can't deduce template"
1779 " argument for %qD", cand
);
1780 return error_mark_node
;
1786 = non_reference (TREE_TYPE (TREE_TYPE (winner
)));
1788 if (!same_type_ignoring_top_level_qualifiers_p (winner_type
,
1793 error ("ambiguous default type conversion from %qT",
1795 inform (input_location
,
1796 " candidate conversions include %qD and %qD",
1799 return error_mark_node
;
1809 tree type
= non_reference (TREE_TYPE (TREE_TYPE (winner
)));
1810 return build_user_type_conversion (type
, expr
, LOOKUP_NORMAL
,
1811 tf_warning_or_error
);
1817 /* Implements integral promotion (4.1) and float->double promotion. */
1820 type_promotes_to (tree type
)
1824 if (type
== error_mark_node
)
1825 return error_mark_node
;
1827 type
= TYPE_MAIN_VARIANT (type
);
1829 /* Check for promotions of target-defined types first. */
1830 promoted_type
= targetm
.promoted_type (type
);
1832 return promoted_type
;
1834 /* bool always promotes to int (not unsigned), even if it's the same
1836 if (TREE_CODE (type
) == BOOLEAN_TYPE
)
1837 type
= integer_type_node
;
1839 /* Normally convert enums to int, but convert wide enums to something
1840 wider. Scoped enums don't promote, but pretend they do for backward
1841 ABI bug compatibility wrt varargs. */
1842 else if (TREE_CODE (type
) == ENUMERAL_TYPE
1843 || type
== char16_type_node
1844 || type
== char32_type_node
1845 || type
== wchar_type_node
)
1849 if (TREE_CODE (type
) == ENUMERAL_TYPE
)
1851 prom
= ENUM_UNDERLYING_TYPE (prom
);
1852 if (!ENUM_IS_SCOPED (type
)
1853 && ENUM_FIXED_UNDERLYING_TYPE_P (type
))
1855 /* ISO C++17, 7.6/4. A prvalue of an unscoped enumeration type
1856 whose underlying type is fixed (10.2) can be converted to a
1857 prvalue of its underlying type. Moreover, if integral promotion
1858 can be applied to its underlying type, a prvalue of an unscoped
1859 enumeration type whose underlying type is fixed can also be
1860 converted to a prvalue of the promoted underlying type. */
1861 return type_promotes_to (prom
);
1865 int precision
= MAX (TYPE_PRECISION (type
),
1866 TYPE_PRECISION (integer_type_node
));
1867 tree totype
= c_common_type_for_size (precision
, 0);
1868 if (TYPE_UNSIGNED (prom
)
1869 && ! int_fits_type_p (TYPE_MAX_VALUE (prom
), totype
))
1870 prom
= c_common_type_for_size (precision
, 1);
1873 if (SCOPED_ENUM_P (type
))
1875 if (abi_version_crosses (6)
1876 && TYPE_MODE (prom
) != TYPE_MODE (type
))
1877 warning (OPT_Wabi
, "scoped enum %qT passed through ... as "
1878 "%qT before -fabi-version=6, %qT after",
1879 type
, prom
, ENUM_UNDERLYING_TYPE (type
));
1880 if (!abi_version_at_least (6))
1886 else if (c_promoting_integer_type_p (type
))
1888 /* Retain unsignedness if really not getting bigger. */
1889 if (TYPE_UNSIGNED (type
)
1890 && TYPE_PRECISION (type
) == TYPE_PRECISION (integer_type_node
))
1891 type
= unsigned_type_node
;
1893 type
= integer_type_node
;
1895 else if (type
== float_type_node
)
1896 type
= double_type_node
;
1901 /* The routines below this point are carefully written to conform to
1902 the standard. They use the same terminology, and follow the rules
1903 closely. Although they are used only in pt.c at the moment, they
1904 should presumably be used everywhere in the future. */
1906 /* True iff EXPR can be converted to TYPE via a qualification conversion.
1907 Callers should check for identical types before calling this function. */
1910 can_convert_qual (tree type
, tree expr
)
1912 tree expr_type
= TREE_TYPE (expr
);
1913 gcc_assert (!same_type_p (type
, expr_type
));
1915 if (TYPE_PTR_P (type
) && TYPE_PTR_P (expr_type
))
1916 return comp_ptr_ttypes (TREE_TYPE (type
), TREE_TYPE (expr_type
));
1917 else if (TYPE_PTRMEM_P (type
) && TYPE_PTRMEM_P (expr_type
))
1918 return (same_type_p (TYPE_PTRMEM_CLASS_TYPE (type
),
1919 TYPE_PTRMEM_CLASS_TYPE (expr_type
))
1920 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type
),
1921 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type
)));
1926 /* Attempt to perform qualification conversions on EXPR to convert it
1927 to TYPE. Return the resulting expression, or error_mark_node if
1928 the conversion was impossible. */
1931 perform_qualification_conversions (tree type
, tree expr
)
1935 expr_type
= TREE_TYPE (expr
);
1937 if (same_type_p (type
, expr_type
))
1939 else if (can_convert_qual (type
, expr
))
1940 return build_nop (type
, expr
);
1942 return error_mark_node
;
1945 /* True iff T is a transaction-safe function type. */
1948 tx_safe_fn_type_p (tree t
)
1950 if (TREE_CODE (t
) != FUNCTION_TYPE
1951 && TREE_CODE (t
) != METHOD_TYPE
)
1953 return !!lookup_attribute ("transaction_safe", TYPE_ATTRIBUTES (t
));
1956 /* Return the transaction-unsafe variant of transaction-safe function type
1960 tx_unsafe_fn_variant (tree t
)
1962 gcc_assert (tx_safe_fn_type_p (t
));
1963 tree attrs
= remove_attribute ("transaction_safe",
1964 TYPE_ATTRIBUTES (t
));
1965 return cp_build_type_attribute_variant (t
, attrs
);
1968 /* Return true iff FROM can convert to TO by a transaction-safety
1972 can_convert_tx_safety (tree to
, tree from
)
1974 return (flag_tm
&& tx_safe_fn_type_p (from
)
1975 && same_type_p (to
, tx_unsafe_fn_variant (from
)));
1978 /* Return true iff FROM can convert to TO by dropping noexcept. */
1981 noexcept_conv_p (tree to
, tree from
)
1983 if (!flag_noexcept_type
)
1986 tree t
= non_reference (to
);
1988 if (TYPE_PTRMEMFUNC_P (t
)
1989 && TYPE_PTRMEMFUNC_P (f
))
1991 t
= TYPE_PTRMEMFUNC_FN_TYPE (t
);
1992 f
= TYPE_PTRMEMFUNC_FN_TYPE (f
);
1994 if (TREE_CODE (t
) == POINTER_TYPE
1995 && TREE_CODE (f
) == POINTER_TYPE
)
2000 tree_code code
= TREE_CODE (f
);
2001 if (TREE_CODE (t
) != code
)
2003 if (code
!= FUNCTION_TYPE
&& code
!= METHOD_TYPE
)
2005 if (!type_throw_all_p (t
)
2006 || type_throw_all_p (f
))
2008 tree v
= build_exception_variant (f
, NULL_TREE
);
2009 return same_type_p (t
, v
);
2012 /* Return true iff FROM can convert to TO by a function pointer conversion. */
2015 fnptr_conv_p (tree to
, tree from
)
2017 tree t
= non_reference (to
);
2019 if (TYPE_PTRMEMFUNC_P (t
)
2020 && TYPE_PTRMEMFUNC_P (f
))
2022 t
= TYPE_PTRMEMFUNC_FN_TYPE (t
);
2023 f
= TYPE_PTRMEMFUNC_FN_TYPE (f
);
2025 if (TREE_CODE (t
) == POINTER_TYPE
2026 && TREE_CODE (f
) == POINTER_TYPE
)
2032 return (noexcept_conv_p (t
, f
)
2033 || can_convert_tx_safety (t
, f
));
2036 /* Return FN with any NOP_EXPRs stripped that represent function pointer
2037 conversions or conversions to the same type. */
2040 strip_fnptr_conv (tree fn
)
2042 while (TREE_CODE (fn
) == NOP_EXPR
)
2044 tree op
= TREE_OPERAND (fn
, 0);
2045 tree ft
= TREE_TYPE (fn
);
2046 tree ot
= TREE_TYPE (op
);
2047 if (same_type_p (ft
, ot
)
2048 || fnptr_conv_p (ft
, ot
))