1 /* Language-level data type conversion for GNU C++.
2 Copyright (C) 1987-2021 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"
38 #include "escaped_string.h"
40 static tree
convert_to_pointer_force (tree
, tree
, tsubst_flags_t
);
41 static tree
build_type_conversion (tree
, tree
);
42 static tree
build_up_reference (tree
, tree
, int, tree
, tsubst_flags_t
);
43 static void diagnose_ref_binding (location_t
, tree
, tree
, tree
);
45 /* Change of width--truncation and extension of integers or reals--
46 is represented with NOP_EXPR. Proper functioning of many things
47 assumes that no other conversions can be NOP_EXPRs.
49 Conversion between integer and pointer is represented with CONVERT_EXPR.
50 Converting integer to real uses FLOAT_EXPR
51 and real to integer uses FIX_TRUNC_EXPR.
53 Here is a list of all the functions that assume that widening and
54 narrowing is always done with a NOP_EXPR:
55 In convert.c, convert_to_integer[_maybe_fold].
56 In c-typeck.c, build_binary_op_nodefault (boolean ops),
57 and c_common_truthvalue_conversion.
58 In expr.c: expand_expr, for operands of a MULT_EXPR.
59 In fold-const.c: fold.
60 In tree.c: get_narrower and get_unwidened.
62 C++: in multiple-inheritance, converting between pointers may involve
63 adjusting them by a delta stored within the class definition. */
65 /* Subroutines of `convert'. */
67 /* if converting pointer to pointer
68 if dealing with classes, check for derived->base or vice versa
69 else if dealing with method pointers, delegate
71 else if converting class, pass off to build_type_conversion
72 else try C-style pointer conversion. */
75 cp_convert_to_pointer (tree type
, tree expr
, bool dofold
,
76 tsubst_flags_t complain
)
78 tree intype
= TREE_TYPE (expr
);
81 location_t loc
= cp_expr_loc_or_input_loc (expr
);
83 if (intype
== error_mark_node
)
84 return error_mark_node
;
86 if (MAYBE_CLASS_TYPE_P (intype
))
88 intype
= complete_type (intype
);
89 if (!COMPLETE_TYPE_P (intype
))
91 if (complain
& tf_error
)
92 error_at (loc
, "cannot convert from incomplete type %qH to %qI",
94 return error_mark_node
;
97 rval
= build_type_conversion (type
, expr
);
100 if ((complain
& tf_error
)
101 && rval
== error_mark_node
)
102 error_at (loc
, "conversion of %qE from %qH to %qI is ambiguous",
108 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
109 if (TYPE_PTR_P (type
)
110 && (TREE_CODE (TREE_TYPE (type
)) == FUNCTION_TYPE
111 || VOID_TYPE_P (TREE_TYPE (type
))))
113 if (TYPE_PTRMEMFUNC_P (intype
)
114 || TREE_CODE (intype
) == METHOD_TYPE
)
115 return convert_member_func_to_ptr (type
, expr
, complain
);
116 if (TYPE_PTR_P (TREE_TYPE (expr
)))
117 return build_nop (type
, expr
);
118 intype
= TREE_TYPE (expr
);
121 if (expr
== error_mark_node
)
122 return error_mark_node
;
124 form
= TREE_CODE (intype
);
126 if (INDIRECT_TYPE_P (intype
))
128 intype
= TYPE_MAIN_VARIANT (intype
);
130 if (TYPE_MAIN_VARIANT (type
) != intype
132 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
133 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type
))
134 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype
))
135 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
137 enum tree_code code
= PLUS_EXPR
;
143 intype_class
= TREE_TYPE (intype
);
144 type_class
= TREE_TYPE (type
);
146 same_p
= same_type_p (TYPE_MAIN_VARIANT (intype_class
),
147 TYPE_MAIN_VARIANT (type_class
));
149 /* Try derived to base conversion. */
151 binfo
= lookup_base (intype_class
, type_class
, ba_check
,
153 if (!same_p
&& !binfo
)
155 /* Try base to derived conversion. */
156 binfo
= lookup_base (type_class
, intype_class
, ba_check
,
160 if (binfo
== error_mark_node
)
161 return error_mark_node
;
165 expr
= build_base_path (code
, expr
, binfo
, 0, complain
);
166 /* Add any qualifier conversions. */
167 return build_nop (type
, expr
);
171 if (TYPE_PTRMEMFUNC_P (type
))
173 if (complain
& tf_error
)
174 error_at (loc
, "cannot convert %qE from type %qH to type %qI",
176 return error_mark_node
;
179 return build_nop (type
, expr
);
181 else if ((TYPE_PTRDATAMEM_P (type
) && TYPE_PTRDATAMEM_P (intype
))
182 || (TYPE_PTRMEMFUNC_P (type
) && TYPE_PTRMEMFUNC_P (intype
)))
183 return convert_ptrmem (type
, expr
, /*allow_inverse_p=*/false,
184 /*c_cast_p=*/false, complain
);
185 else if (TYPE_PTRMEMFUNC_P (intype
))
189 if (TREE_CODE (expr
) == PTRMEM_CST
)
190 return cp_convert_to_pointer (type
, PTRMEM_CST_MEMBER (expr
),
192 else if (TREE_CODE (expr
) == OFFSET_REF
)
194 tree object
= TREE_OPERAND (expr
, 0);
195 return get_member_function_from_ptrfunc (&object
,
196 TREE_OPERAND (expr
, 1),
200 if (complain
& tf_error
)
201 error_at (loc
, "cannot convert %qE from type %qH to type %qI",
203 return error_mark_node
;
206 if (null_ptr_cst_p (expr
))
208 if (TYPE_PTRMEMFUNC_P (type
))
209 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), expr
, 0,
210 /*c_cast_p=*/false, complain
);
212 if (complain
& tf_warning
)
213 maybe_warn_zero_as_null_pointer_constant (expr
, loc
);
215 /* A NULL pointer-to-data-member is represented by -1, not by
217 tree val
= (TYPE_PTRDATAMEM_P (type
)
218 ? build_int_cst_type (type
, -1)
219 : build_int_cst (type
, 0));
221 return (TREE_SIDE_EFFECTS (expr
)
222 ? build2 (COMPOUND_EXPR
, type
, expr
, val
) : val
);
224 else if (TYPE_PTRMEM_P (type
) && INTEGRAL_CODE_P (form
))
226 if (complain
& tf_error
)
227 error_at (loc
, "invalid conversion from %qH to %qI", intype
, type
);
228 return error_mark_node
;
231 if (INTEGRAL_CODE_P (form
))
233 if (TYPE_PRECISION (intype
) == POINTER_SIZE
)
234 return build1 (CONVERT_EXPR
, type
, expr
);
235 expr
= cp_convert (c_common_type_for_size (TYPE_PRECISION (type
), 0), expr
,
237 /* Modes may be different but sizes should be the same. There
238 is supposed to be some integral type that is the same width
240 gcc_assert (GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (TREE_TYPE (expr
)))
241 == GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (type
)));
243 /* FIXME needed because convert_to_pointer_maybe_fold still folds
244 conversion of constants. */
246 return build1 (CONVERT_EXPR
, type
, expr
);
248 return convert_to_pointer_maybe_fold (type
, expr
, dofold
);
251 if (type_unknown_p (expr
))
252 return instantiate_type (type
, expr
, complain
);
254 if (complain
& tf_error
)
255 error_at (loc
, "cannot convert %qE from type %qH to type %qI",
257 return error_mark_node
;
260 /* Like convert, except permit conversions to take place which
261 are not normally allowed due to access restrictions
262 (such as conversion from sub-type to private super-type). */
265 convert_to_pointer_force (tree type
, tree expr
, tsubst_flags_t complain
)
267 tree intype
= TREE_TYPE (expr
);
268 enum tree_code form
= TREE_CODE (intype
);
270 if (form
== POINTER_TYPE
)
272 intype
= TYPE_MAIN_VARIANT (intype
);
274 if (TYPE_MAIN_VARIANT (type
) != intype
275 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
276 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type
))
277 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype
))
278 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
280 enum tree_code code
= PLUS_EXPR
;
283 binfo
= lookup_base (TREE_TYPE (intype
), TREE_TYPE (type
),
284 ba_unique
, NULL
, complain
);
287 binfo
= lookup_base (TREE_TYPE (type
), TREE_TYPE (intype
),
288 ba_unique
, NULL
, complain
);
291 if (binfo
== error_mark_node
)
292 return error_mark_node
;
295 expr
= build_base_path (code
, expr
, binfo
, 0, complain
);
296 if (expr
== error_mark_node
)
297 return error_mark_node
;
298 /* Add any qualifier conversions. */
299 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr
)),
301 expr
= build_nop (type
, expr
);
307 return cp_convert_to_pointer (type
, expr
, /*fold*/false, complain
);
310 /* We are passing something to a function which requires a reference.
311 The type we are interested in is in TYPE. The initial
312 value we have to begin with is in ARG.
314 FLAGS controls how we manage access checking.
315 DIRECT_BIND in FLAGS controls how any temporaries are generated.
316 If DIRECT_BIND is set, DECL is the reference we're binding to. */
319 build_up_reference (tree type
, tree arg
, int flags
, tree decl
,
320 tsubst_flags_t complain
)
323 tree argtype
= TREE_TYPE (arg
);
324 tree target_type
= TREE_TYPE (type
);
326 gcc_assert (TYPE_REF_P (type
));
328 if ((flags
& DIRECT_BIND
) && ! lvalue_p (arg
))
330 /* Create a new temporary variable. We can't just use a TARGET_EXPR
331 here because it needs to live as long as DECL. */
334 arg
= make_temporary_var_for_ref_to_temp (decl
, target_type
);
336 /* Process the initializer for the declaration. */
337 DECL_INITIAL (arg
) = targ
;
338 cp_finish_decl (arg
, targ
, /*init_const_expr_p=*/false, NULL_TREE
,
339 LOOKUP_ONLYCONVERTING
|DIRECT_BIND
);
341 else if (!(flags
& DIRECT_BIND
) && ! obvalue_p (arg
))
342 return get_target_expr_sfinae (arg
, complain
);
344 /* If we had a way to wrap this up, and say, if we ever needed its
345 address, transform all occurrences of the register, into a memory
346 reference we could win better. */
347 rval
= cp_build_addr_expr (arg
, complain
);
348 if (rval
== error_mark_node
)
349 return error_mark_node
;
351 if ((flags
& LOOKUP_PROTECT
)
352 && TYPE_MAIN_VARIANT (argtype
) != TYPE_MAIN_VARIANT (target_type
)
353 && MAYBE_CLASS_TYPE_P (argtype
)
354 && MAYBE_CLASS_TYPE_P (target_type
))
356 /* We go through lookup_base for the access control. */
357 tree binfo
= lookup_base (argtype
, target_type
, ba_check
,
359 if (binfo
== error_mark_node
)
360 return error_mark_node
;
361 if (binfo
== NULL_TREE
)
362 return error_not_base_type (target_type
, argtype
);
363 rval
= build_base_path (PLUS_EXPR
, rval
, binfo
, 1, complain
);
367 = convert_to_pointer_force (build_pointer_type (target_type
),
369 return build_nop (type
, rval
);
372 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
373 INTYPE is the original rvalue type and DECL is an optional _DECL node
376 [dcl.init.ref] says that if an rvalue is used to
377 initialize a reference, then the reference must be to a
378 non-volatile const type. */
381 diagnose_ref_binding (location_t loc
, tree reftype
, tree intype
, tree decl
)
383 tree ttl
= TREE_TYPE (reftype
);
385 if (!TYPE_REF_IS_RVALUE (reftype
)
386 && !CP_TYPE_CONST_NON_VOLATILE_P (ttl
))
390 if (CP_TYPE_VOLATILE_P (ttl
) && decl
)
391 msg
= G_("initialization of volatile reference type %q#T from "
392 "rvalue of type %qT");
393 else if (CP_TYPE_VOLATILE_P (ttl
))
394 msg
= G_("conversion to volatile reference type %q#T "
395 "from rvalue of type %qT");
397 msg
= G_("initialization of non-const reference type %q#T from "
398 "rvalue of type %qT");
400 msg
= G_("conversion to non-const reference type %q#T from "
401 "rvalue of type %qT");
403 permerror (loc
, msg
, reftype
, intype
);
407 /* For C++: Only need to do one-level references, but cannot
408 get tripped up on signed/unsigned differences.
410 DECL is either NULL_TREE or the _DECL node for a reference that is being
411 initialized. It can be error_mark_node if we don't know the _DECL but
412 we know it's an initialization. */
415 convert_to_reference (tree reftype
, tree expr
, int convtype
,
416 int flags
, tree decl
, tsubst_flags_t complain
)
418 tree type
= TYPE_MAIN_VARIANT (TREE_TYPE (reftype
));
420 tree rval
= NULL_TREE
;
421 tree rval_as_conversion
= NULL_TREE
;
422 bool can_convert_intype_to_type
;
423 location_t loc
= cp_expr_loc_or_input_loc (expr
);
425 if (TREE_CODE (type
) == FUNCTION_TYPE
426 && TREE_TYPE (expr
) == unknown_type_node
)
427 expr
= instantiate_type (type
, expr
, complain
);
429 if (expr
== error_mark_node
)
430 return error_mark_node
;
432 intype
= TREE_TYPE (expr
);
434 gcc_assert (!TYPE_REF_P (intype
));
435 gcc_assert (TYPE_REF_P (reftype
));
437 intype
= TYPE_MAIN_VARIANT (intype
);
439 can_convert_intype_to_type
= can_convert_standard (type
, intype
, complain
);
441 if (!can_convert_intype_to_type
442 && (convtype
& CONV_IMPLICIT
) && MAYBE_CLASS_TYPE_P (intype
)
443 && ! (flags
& LOOKUP_NO_CONVERSION
))
445 /* Look for a user-defined conversion to lvalue that we can use. */
448 = build_type_conversion (reftype
, expr
);
450 if (rval_as_conversion
&& rval_as_conversion
!= error_mark_node
451 && lvalue_p (rval_as_conversion
))
453 expr
= rval_as_conversion
;
454 rval_as_conversion
= NULL_TREE
;
456 can_convert_intype_to_type
= 1;
460 if (((convtype
& CONV_STATIC
)
461 && can_convert_standard (intype
, type
, complain
))
462 || ((convtype
& CONV_IMPLICIT
) && can_convert_intype_to_type
))
465 tree ttl
= TREE_TYPE (reftype
);
466 tree ttr
= lvalue_type (expr
);
468 if ((complain
& tf_error
)
469 && ! lvalue_p (expr
))
470 diagnose_ref_binding (loc
, reftype
, intype
, decl
);
472 if (! (convtype
& CONV_CONST
)
473 && !at_least_as_qualified_p (ttl
, ttr
))
475 if (complain
& tf_error
)
476 permerror (loc
, "conversion from %qH to %qI discards qualifiers",
479 return error_mark_node
;
483 return build_up_reference (reftype
, expr
, flags
, decl
, complain
);
485 else if ((convtype
& CONV_REINTERPRET
) && obvalue_p (expr
))
487 /* When casting an lvalue to a reference type, just convert into
488 a pointer to the new type and deference it. This is allowed
489 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
490 should be done directly (jason). (int &)ri ---> *(int*)&ri */
492 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
494 if ((complain
& tf_warning
)
495 && TYPE_PTR_P (intype
)
496 && (comptypes (TREE_TYPE (intype
), type
,
497 COMPARE_BASE
| COMPARE_DERIVED
)))
498 warning_at (loc
, 0, "casting %qT to %qT does not dereference pointer",
501 rval
= cp_build_addr_expr (expr
, complain
);
502 if (rval
!= error_mark_node
)
503 rval
= convert_force (build_pointer_type (TREE_TYPE (reftype
)),
505 if (rval
!= error_mark_node
)
506 rval
= build1 (NOP_EXPR
, reftype
, rval
);
510 rval
= convert_for_initialization (NULL_TREE
, type
, expr
, flags
,
511 ICR_CONVERTING
, 0, 0, complain
);
512 if (rval
== NULL_TREE
|| rval
== error_mark_node
)
514 if (complain
& tf_error
)
515 diagnose_ref_binding (loc
, reftype
, intype
, decl
);
516 rval
= build_up_reference (reftype
, rval
, flags
, decl
, complain
);
521 /* If we found a way to convert earlier, then use it. */
525 if (complain
& tf_error
)
526 error_at (loc
, "cannot convert type %qH to type %qI", intype
, reftype
);
528 return error_mark_node
;
531 /* We are using a reference VAL for its value. Bash that reference all the
532 way down to its lowest form. */
535 convert_from_reference (tree val
)
538 && TYPE_REF_P (TREE_TYPE (val
)))
540 tree t
= TREE_TYPE (TREE_TYPE (val
));
541 tree ref
= build1 (INDIRECT_REF
, t
, val
);
544 /* We *must* set TREE_READONLY when dereferencing a pointer to const,
545 so that we get the proper error message if the result is used
546 to assign to. Also, &* is supposed to be a no-op. */
547 TREE_READONLY (ref
) = CP_TYPE_CONST_P (t
);
548 TREE_THIS_VOLATILE (ref
) = CP_TYPE_VOLATILE_P (t
);
549 TREE_SIDE_EFFECTS (ref
)
550 = (TREE_THIS_VOLATILE (ref
) || TREE_SIDE_EFFECTS (val
));
557 /* Really perform an lvalue-to-rvalue conversion, including copying an
558 argument of class type into a temporary. */
561 force_rvalue (tree expr
, tsubst_flags_t complain
)
563 tree type
= TREE_TYPE (expr
);
564 if (MAYBE_CLASS_TYPE_P (type
) && TREE_CODE (expr
) != TARGET_EXPR
)
566 releasing_vec
args (make_tree_vector_single (expr
));
567 expr
= build_special_member_call (NULL_TREE
, complete_ctor_identifier
,
568 &args
, type
, LOOKUP_NORMAL
, complain
);
569 expr
= build_cplus_new (type
, expr
, complain
);
572 expr
= decay_conversion (expr
, complain
);
578 /* If EXPR and ORIG are INTEGER_CSTs, return a version of EXPR that has
579 TREE_OVERFLOW set only if it is set in ORIG. Otherwise, return EXPR
583 ignore_overflows (tree expr
, tree orig
)
585 tree stripped_expr
= tree_strip_any_location_wrapper (expr
);
586 tree stripped_orig
= tree_strip_any_location_wrapper (orig
);
588 if (TREE_CODE (stripped_expr
) == INTEGER_CST
589 && TREE_CODE (stripped_orig
) == INTEGER_CST
590 && TREE_OVERFLOW (stripped_expr
) != TREE_OVERFLOW (stripped_orig
))
592 gcc_assert (!TREE_OVERFLOW (stripped_orig
));
593 /* Ensure constant sharing. */
594 stripped_expr
= wide_int_to_tree (TREE_TYPE (stripped_expr
),
595 wi::to_wide (stripped_expr
));
598 return preserve_any_location_wrapper (stripped_expr
, expr
);
601 /* Fold away simple conversions, but make sure TREE_OVERFLOW is set
602 properly and propagate TREE_NO_WARNING if folding EXPR results
603 in the same expression code. */
606 cp_fold_convert (tree type
, tree expr
)
609 if (TREE_TYPE (expr
) == type
)
611 else if (TREE_CODE (expr
) == PTRMEM_CST
612 && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type
),
613 PTRMEM_CST_CLASS (expr
)))
615 /* Avoid wrapping a PTRMEM_CST in NOP_EXPR. */
616 conv
= copy_node (expr
);
617 TREE_TYPE (conv
) = type
;
619 else if (TYPE_PTRMEM_P (type
))
621 conv
= convert_ptrmem (type
, expr
, true, false,
622 tf_warning_or_error
);
623 conv
= cp_fully_fold (conv
);
627 conv
= fold_convert (type
, expr
);
628 conv
= ignore_overflows (conv
, expr
);
631 if (TREE_CODE (expr
) == TREE_CODE (conv
))
632 copy_warning (conv
, expr
);
637 /* C++ conversions, preference to static cast conversions. */
640 cp_convert (tree type
, tree expr
, tsubst_flags_t complain
)
642 return ocp_convert (type
, expr
, CONV_OLD_CONVERT
, LOOKUP_NORMAL
, complain
);
645 /* C++ equivalent of convert_and_check but using cp_convert as the
648 Convert EXPR to TYPE, warning about conversion problems with constants.
649 Invoke this function on every expression that is converted implicitly,
650 i.e. because of language rules and not because of an explicit cast. */
653 cp_convert_and_check (tree type
, tree expr
, tsubst_flags_t complain
)
657 if (TREE_TYPE (expr
) == type
)
659 if (expr
== error_mark_node
)
661 result
= cp_convert (type
, expr
, complain
);
663 if ((complain
& tf_warning
)
664 && c_inhibit_evaluation_warnings
== 0)
666 tree folded
= cp_fully_fold (expr
);
669 folded_result
= result
;
672 /* Avoid bogus -Wparentheses warnings. */
673 warning_sentinel
w (warn_parentheses
);
674 warning_sentinel
c (warn_int_in_bool_context
);
675 folded_result
= cp_convert (type
, folded
, tf_none
);
677 folded_result
= fold_simple (folded_result
);
678 if (!TREE_OVERFLOW_P (folded
)
679 && folded_result
!= error_mark_node
)
680 warnings_for_convert_and_check (cp_expr_loc_or_input_loc (expr
),
681 type
, folded
, folded_result
);
689 FLAGS indicates how we should behave. */
692 ocp_convert (tree type
, tree expr
, int convtype
, int flags
,
693 tsubst_flags_t complain
)
696 enum tree_code code
= TREE_CODE (type
);
697 const char *invalid_conv_diag
;
699 location_t loc
= cp_expr_loc_or_input_loc (expr
);
700 bool dofold
= (convtype
& CONV_FOLD
);
702 if (error_operand_p (e
) || type
== error_mark_node
)
703 return error_mark_node
;
705 if (TREE_CODE (e
) == COMPOUND_EXPR
)
707 e
= ocp_convert (type
, TREE_OPERAND (e
, 1), convtype
, flags
, complain
);
708 if (e
== error_mark_node
)
709 return error_mark_node
;
710 if (e
== TREE_OPERAND (expr
, 1))
712 return build2_loc (EXPR_LOCATION (expr
), COMPOUND_EXPR
, TREE_TYPE (e
),
713 TREE_OPERAND (expr
, 0), e
);
716 complete_type (type
);
717 complete_type (TREE_TYPE (expr
));
719 if ((invalid_conv_diag
720 = targetm
.invalid_conversion (TREE_TYPE (expr
), type
)))
722 if (complain
& tf_error
)
723 error (invalid_conv_diag
);
724 return error_mark_node
;
727 /* FIXME remove when moving to c_fully_fold model. */
728 if (!CLASS_TYPE_P (type
))
730 e
= mark_rvalue_use (e
);
731 tree v
= scalar_constant_value (e
);
732 if (!error_operand_p (v
))
735 if (error_operand_p (e
))
736 return error_mark_node
;
738 if (NULLPTR_TYPE_P (type
) && null_ptr_cst_p (e
))
740 if (complain
& tf_warning
)
741 maybe_warn_zero_as_null_pointer_constant (e
, loc
);
743 if (!TREE_SIDE_EFFECTS (e
))
747 if (MAYBE_CLASS_TYPE_P (type
) && (convtype
& CONV_FORCE_TEMP
))
748 /* We need a new temporary; don't take this shortcut. */;
749 else if (same_type_ignoring_top_level_qualifiers_p (type
, TREE_TYPE (e
)))
751 tree etype
= TREE_TYPE (e
);
752 if (same_type_p (type
, etype
))
753 /* The call to fold will not always remove the NOP_EXPR as
754 might be expected, since if one of the types is a typedef;
755 the comparison in fold is just equality of pointers, not a
756 call to comptypes. We don't call fold in this case because
757 that can result in infinite recursion; fold will call
758 convert, which will call ocp_convert, etc. */
760 /* For complex data types, we need to perform componentwise
762 else if (TREE_CODE (type
) == COMPLEX_TYPE
)
763 return convert_to_complex_maybe_fold (type
, e
, dofold
);
764 else if (VECTOR_TYPE_P (type
))
765 return convert_to_vector (type
, rvalue (e
));
766 else if (TREE_CODE (e
) == TARGET_EXPR
)
768 /* Don't build a NOP_EXPR of class type. Instead, change the
769 type of the temporary. */
770 gcc_assert (same_type_ignoring_top_level_qualifiers_p (type
, etype
));
771 TREE_TYPE (e
) = TREE_TYPE (TARGET_EXPR_SLOT (e
)) = type
;
774 else if (TREE_CODE (e
) == CONSTRUCTOR
)
776 gcc_assert (same_type_ignoring_top_level_qualifiers_p (type
, etype
));
777 TREE_TYPE (e
) = type
;
782 /* We shouldn't be treating objects of ADDRESSABLE type as
784 gcc_assert (!TREE_ADDRESSABLE (type
));
785 return build_nop (type
, e
);
789 e1
= targetm
.convert_to_type (type
, e
);
793 if (code
== VOID_TYPE
&& (convtype
& CONV_STATIC
))
795 e
= convert_to_void (e
, ICV_CAST
, complain
);
799 if (INTEGRAL_CODE_P (code
))
801 tree intype
= TREE_TYPE (e
);
804 if (TREE_CODE (type
) == ENUMERAL_TYPE
)
806 /* enum = enum, enum = int, enum = float, (enum)pointer are all
808 if (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype
)
809 || TREE_CODE (intype
) == REAL_TYPE
)
810 && ! (convtype
& CONV_STATIC
))
811 || TYPE_PTR_P (intype
))
813 if (complain
& tf_error
)
814 permerror (loc
, "conversion from %q#T to %q#T", intype
, type
);
816 return error_mark_node
;
819 /* [expr.static.cast]
821 8. A value of integral or enumeration type can be explicitly
822 converted to an enumeration type. The value is unchanged if
823 the original value is within the range of the enumeration
824 values. Otherwise, the resulting enumeration value is
826 tree val
= fold_for_warn (e
);
827 if ((complain
& tf_warning
)
828 && TREE_CODE (val
) == INTEGER_CST
829 && ENUM_UNDERLYING_TYPE (type
)
830 && !int_fits_type_p (val
, ENUM_UNDERLYING_TYPE (type
)))
831 warning_at (loc
, OPT_Wconversion
,
832 "the result of the conversion is unspecified because "
833 "%qE is outside the range of type %qT",
836 if (MAYBE_CLASS_TYPE_P (intype
))
839 rval
= build_type_conversion (type
, e
);
842 if (complain
& tf_error
)
843 error_at (loc
, "%q#T used where a %qT was expected", intype
, type
);
844 return error_mark_node
;
846 if (code
== BOOLEAN_TYPE
)
848 if (VOID_TYPE_P (intype
))
850 if (complain
& tf_error
)
852 "could not convert %qE from %<void%> to %<bool%>",
854 return error_mark_node
;
857 if (VECTOR_TYPE_P (intype
) && !gnu_vector_type_p (intype
))
859 if (complain
& tf_error
)
860 error_at (loc
, "could not convert %qE from %qH to %qI", expr
,
861 TREE_TYPE (expr
), type
);
862 return error_mark_node
;
865 /* We can't implicitly convert a scoped enum to bool, so convert
866 to the underlying type first. */
867 if (SCOPED_ENUM_P (intype
) && (convtype
& CONV_STATIC
))
868 e
= build_nop (ENUM_UNDERLYING_TYPE (intype
), e
);
869 if (complain
& tf_warning
)
870 return cp_truthvalue_conversion (e
, complain
);
873 /* Prevent bogus -Wint-in-bool-context warnings coming
874 from c_common_truthvalue_conversion down the line. */
875 warning_sentinel
w (warn_int_in_bool_context
);
876 warning_sentinel
c (warn_sign_compare
);
877 return cp_truthvalue_conversion (e
, complain
);
881 converted
= convert_to_integer_maybe_fold (type
, e
, dofold
);
883 /* Ignore any integer overflow caused by the conversion. */
884 return ignore_overflows (converted
, e
);
886 if (INDIRECT_TYPE_P (type
) || TYPE_PTRMEM_P (type
))
887 return cp_convert_to_pointer (type
, e
, dofold
, complain
);
888 if (code
== VECTOR_TYPE
)
890 tree in_vtype
= TREE_TYPE (e
);
891 if (MAYBE_CLASS_TYPE_P (in_vtype
))
894 ret_val
= build_type_conversion (type
, e
);
897 if (complain
& tf_error
)
898 error_at (loc
, "%q#T used where a %qT was expected",
900 return error_mark_node
;
902 return convert_to_vector (type
, rvalue (e
));
904 if (code
== REAL_TYPE
|| code
== COMPLEX_TYPE
)
906 if (MAYBE_CLASS_TYPE_P (TREE_TYPE (e
)))
909 rval
= build_type_conversion (type
, e
);
912 else if (complain
& tf_error
)
914 "%q#T used where a floating-point value was expected",
917 if (code
== REAL_TYPE
)
918 return convert_to_real_maybe_fold (type
, e
, dofold
);
919 else if (code
== COMPLEX_TYPE
)
920 return convert_to_complex_maybe_fold (type
, e
, dofold
);
923 /* New C++ semantics: since assignment is now based on
924 memberwise copying, if the rhs type is derived from the
925 lhs type, then we may still do a conversion. */
926 if (RECORD_OR_UNION_CODE_P (code
))
928 tree dtype
= TREE_TYPE (e
);
929 tree ctor
= NULL_TREE
;
931 dtype
= TYPE_MAIN_VARIANT (dtype
);
933 /* Conversion between aggregate types. New C++ semantics allow
934 objects of derived type to be cast to objects of base type.
935 Old semantics only allowed this between pointers.
937 There may be some ambiguity between using a constructor
938 vs. using a type conversion operator when both apply. */
942 if (abstract_virtuals_error_sfinae (NULL_TREE
, type
, complain
))
943 return error_mark_node
;
945 if (BRACE_ENCLOSED_INITIALIZER_P (ctor
))
946 ctor
= perform_implicit_conversion (type
, ctor
, complain
);
947 else if ((flags
& LOOKUP_ONLYCONVERTING
)
948 && ! (CLASS_TYPE_P (dtype
) && DERIVED_FROM_P (type
, dtype
)))
949 /* For copy-initialization, first we create a temp of the proper type
950 with a user-defined conversion sequence, then we direct-initialize
951 the target with the temp (see [dcl.init]). */
952 ctor
= build_user_type_conversion (type
, ctor
, flags
, complain
);
955 releasing_vec
ctor_vec (make_tree_vector_single (ctor
));
956 ctor
= build_special_member_call (NULL_TREE
,
957 complete_ctor_identifier
,
959 type
, flags
, complain
);
962 return build_cplus_new (type
, ctor
, complain
);
965 if (complain
& tf_error
)
967 /* If the conversion failed and expr was an invalid use of pointer to
968 member function, try to report a meaningful error. */
969 if (invalid_nonstatic_memfn_p (loc
, expr
, complain
))
970 /* We displayed the error message. */;
972 error_at (loc
, "conversion from %qH to non-scalar type %qI requested",
973 TREE_TYPE (expr
), type
);
975 return error_mark_node
;
978 /* If CALL is a call, return the callee; otherwise null. */
981 cp_get_callee (tree call
)
983 if (call
== NULL_TREE
)
985 else if (TREE_CODE (call
) == CALL_EXPR
)
986 return CALL_EXPR_FN (call
);
987 else if (TREE_CODE (call
) == AGGR_INIT_EXPR
)
988 return AGGR_INIT_EXPR_FN (call
);
992 /* FN is the callee of a CALL_EXPR or AGGR_INIT_EXPR; return the FUNCTION_DECL
996 cp_get_fndecl_from_callee (tree fn
, bool fold
/* = true */)
1000 if (TREE_CODE (fn
) == FUNCTION_DECL
)
1002 tree type
= TREE_TYPE (fn
);
1003 if (type
== NULL_TREE
|| !INDIRECT_TYPE_P (type
))
1006 fn
= maybe_constant_init (fn
);
1008 if (TREE_CODE (fn
) == ADDR_EXPR
1009 || TREE_CODE (fn
) == FDESC_EXPR
)
1010 fn
= TREE_OPERAND (fn
, 0);
1011 if (TREE_CODE (fn
) == FUNCTION_DECL
)
1016 /* Like get_callee_fndecl, but handles AGGR_INIT_EXPR as well and uses the
1017 constexpr machinery. */
1020 cp_get_callee_fndecl (tree call
)
1022 return cp_get_fndecl_from_callee (cp_get_callee (call
));
1025 /* As above, but not using the constexpr machinery. */
1028 cp_get_callee_fndecl_nofold (tree call
)
1030 return cp_get_fndecl_from_callee (cp_get_callee (call
), false);
1033 /* Subroutine of convert_to_void. Warn if we're discarding something with
1034 attribute [[nodiscard]]. */
1037 maybe_warn_nodiscard (tree expr
, impl_conv_void implicit
)
1039 if (!warn_unused_result
|| c_inhibit_evaluation_warnings
)
1043 if (TREE_CODE (expr
) == TARGET_EXPR
)
1044 call
= TARGET_EXPR_INITIAL (expr
);
1045 location_t loc
= cp_expr_loc_or_input_loc (call
);
1046 tree callee
= cp_get_callee (call
);
1050 tree type
= TREE_TYPE (callee
);
1051 if (TYPE_PTRMEMFUNC_P (type
))
1052 type
= TYPE_PTRMEMFUNC_FN_TYPE (type
);
1053 if (INDIRECT_TYPE_P (type
))
1054 type
= TREE_TYPE (type
);
1056 tree rettype
= TREE_TYPE (type
);
1057 tree fn
= cp_get_fndecl_from_callee (callee
);
1059 if (implicit
!= ICV_CAST
&& fn
1060 && (attr
= lookup_attribute ("nodiscard", DECL_ATTRIBUTES (fn
))))
1063 tree args
= TREE_VALUE (attr
);
1065 msg
.escape (TREE_STRING_POINTER (TREE_VALUE (args
)));
1068 ? G_("ignoring return value of %qD, "
1069 "declared with attribute %<nodiscard%>: %<%s%>")
1070 : G_("ignoring return value of %qD, "
1071 "declared with attribute %<nodiscard%>%s"));
1072 const char *raw_msg
= msg
? (const char *) msg
: "";
1073 auto_diagnostic_group d
;
1074 if (warning_at (loc
, OPT_Wunused_result
, format
, fn
, raw_msg
))
1075 inform (DECL_SOURCE_LOCATION (fn
), "declared here");
1077 else if (implicit
!= ICV_CAST
1078 && (attr
= lookup_attribute ("nodiscard", TYPE_ATTRIBUTES (rettype
))))
1081 tree args
= TREE_VALUE (attr
);
1083 msg
.escape (TREE_STRING_POINTER (TREE_VALUE (args
)));
1086 ? G_("ignoring returned value of type %qT, "
1087 "declared with attribute %<nodiscard%>: %<%s%>")
1088 : G_("ignoring returned value of type %qT, "
1089 "declared with attribute %<nodiscard%>%s"));
1090 const char *raw_msg
= msg
? (const char *) msg
: "";
1091 auto_diagnostic_group d
;
1092 if (warning_at (loc
, OPT_Wunused_result
, format
, rettype
, raw_msg
))
1095 inform (DECL_SOURCE_LOCATION (fn
),
1096 "in call to %qD, declared here", fn
);
1097 inform (DECL_SOURCE_LOCATION (TYPE_NAME (rettype
)),
1098 "%qT declared here", rettype
);
1101 else if (TREE_CODE (expr
) == TARGET_EXPR
1102 && lookup_attribute ("warn_unused_result", TYPE_ATTRIBUTES (type
)))
1104 /* The TARGET_EXPR confuses do_warn_unused_result into thinking that the
1105 result is used, so handle that case here. */
1108 auto_diagnostic_group d
;
1109 if (warning_at (loc
, OPT_Wunused_result
,
1110 "ignoring return value of %qD, "
1111 "declared with attribute %<warn_unused_result%>",
1113 inform (DECL_SOURCE_LOCATION (fn
), "declared here");
1116 warning_at (loc
, OPT_Wunused_result
,
1117 "ignoring return value of function "
1118 "declared with attribute %<warn_unused_result%>");
1122 /* When an expression is used in a void context, its value is discarded and
1123 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
1124 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
1125 in a void context. The C++ standard does not define what an `access' to an
1126 object is, but there is reason to believe that it is the lvalue to rvalue
1127 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
1128 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
1129 indicates that volatile semantics should be the same between C and C++
1130 where ever possible. C leaves it implementation defined as to what
1131 constitutes an access to a volatile. So, we interpret `*vp' as a read of
1132 the volatile object `vp' points to, unless that is an incomplete type. For
1133 volatile references we do not do this interpretation, because that would
1134 make it impossible to ignore the reference return value from functions. We
1135 issue warnings in the confusing cases.
1137 The IMPLICIT is ICV_CAST when the user is explicitly converting an expression
1138 to void via a cast. If an expression is being implicitly converted, IMPLICIT
1139 indicates the context of the implicit conversion. */
1142 convert_to_void (tree expr
, impl_conv_void implicit
, tsubst_flags_t complain
)
1144 location_t loc
= cp_expr_loc_or_input_loc (expr
);
1146 if (expr
== error_mark_node
1147 || TREE_TYPE (expr
) == error_mark_node
)
1148 return error_mark_node
;
1150 expr
= maybe_undo_parenthesized_ref (expr
);
1152 expr
= mark_discarded_use (expr
);
1153 if (implicit
== ICV_CAST
)
1154 /* An explicit cast to void avoids all -Wunused-but-set* warnings. */
1155 mark_exp_read (expr
);
1157 if (!TREE_TYPE (expr
))
1159 if (invalid_nonstatic_memfn_p (loc
, expr
, complain
))
1160 return error_mark_node
;
1161 if (TREE_CODE (expr
) == PSEUDO_DTOR_EXPR
)
1163 if (complain
& tf_error
)
1164 error_at (loc
, "pseudo-destructor is not called");
1165 return error_mark_node
;
1168 /* Explicitly evaluate void-converted concept checks since their
1169 satisfaction may produce ill-formed programs. */
1170 if (concept_check_p (expr
))
1171 expr
= evaluate_concept_check (expr
);
1173 if (VOID_TYPE_P (TREE_TYPE (expr
)))
1175 switch (TREE_CODE (expr
))
1179 /* The two parts of a cond expr might be separate lvalues. */
1180 tree op1
= TREE_OPERAND (expr
,1);
1181 tree op2
= TREE_OPERAND (expr
,2);
1182 bool side_effects
= ((op1
&& TREE_SIDE_EFFECTS (op1
))
1183 || TREE_SIDE_EFFECTS (op2
));
1184 tree new_op1
, new_op2
;
1185 new_op1
= NULL_TREE
;
1186 if (implicit
!= ICV_CAST
&& !side_effects
)
1189 new_op1
= convert_to_void (op1
, ICV_SECOND_OF_COND
, complain
);
1190 new_op2
= convert_to_void (op2
, ICV_THIRD_OF_COND
, complain
);
1195 new_op1
= convert_to_void (op1
, ICV_CAST
, complain
);
1196 new_op2
= convert_to_void (op2
, ICV_CAST
, complain
);
1199 expr
= build3_loc (loc
, COND_EXPR
, TREE_TYPE (new_op2
),
1200 TREE_OPERAND (expr
, 0), new_op1
, new_op2
);
1206 /* The second part of a compound expr contains the value. */
1207 tree op1
= TREE_OPERAND (expr
,1);
1209 if (implicit
!= ICV_CAST
&& !warning_suppressed_p (expr
/* What warning? */))
1210 new_op1
= convert_to_void (op1
, ICV_RIGHT_OF_COMMA
, complain
);
1212 new_op1
= convert_to_void (op1
, ICV_CAST
, complain
);
1216 tree t
= build2_loc (loc
, COMPOUND_EXPR
, TREE_TYPE (new_op1
),
1217 TREE_OPERAND (expr
, 0), new_op1
);
1224 case NON_LVALUE_EXPR
:
1226 /* These have already decayed to rvalue. */
1229 case CALL_EXPR
: /* We have a special meaning for volatile void fn(). */
1230 /* cdtors may return this or void, depending on
1231 targetm.cxx.cdtor_returns_this, but this shouldn't affect our
1232 decisions here: neither nodiscard warnings (nodiscard dtors
1233 are nonsensical and ctors have a different behavior with that
1234 attribute that is handled in the TARGET_EXPR case), nor should
1235 any constexpr or template instantiations be affected by an ABI
1236 property that is, or at least ought to be transparent to the
1238 if (tree fn
= cp_get_callee_fndecl_nofold (expr
))
1239 if (DECL_CONSTRUCTOR_P (fn
) || DECL_DESTRUCTOR_P (fn
))
1242 if (complain
& tf_warning
)
1243 maybe_warn_nodiscard (expr
, implicit
);
1248 tree type
= TREE_TYPE (expr
);
1249 int is_reference
= TYPE_REF_P (TREE_TYPE (TREE_OPERAND (expr
, 0)));
1250 int is_volatile
= TYPE_VOLATILE (type
);
1251 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
1253 /* Can't load the value if we don't know the type. */
1254 if (is_volatile
&& !is_complete
)
1256 if (complain
& tf_warning
)
1260 warning_at (loc
, 0, "conversion to void will not access "
1261 "object of incomplete type %qT", type
);
1263 case ICV_SECOND_OF_COND
:
1264 warning_at (loc
, 0, "indirection will not access object of "
1265 "incomplete type %qT in second operand "
1266 "of conditional expression", type
);
1268 case ICV_THIRD_OF_COND
:
1269 warning_at (loc
, 0, "indirection will not access object of "
1270 "incomplete type %qT in third operand "
1271 "of conditional expression", type
);
1273 case ICV_RIGHT_OF_COMMA
:
1274 warning_at (loc
, 0, "indirection will not access object of "
1275 "incomplete type %qT in right operand of "
1276 "comma operator", type
);
1278 case ICV_LEFT_OF_COMMA
:
1279 warning_at (loc
, 0, "indirection will not access object of "
1280 "incomplete type %qT in left operand of "
1281 "comma operator", type
);
1284 warning_at (loc
, 0, "indirection will not access object of "
1285 "incomplete type %qT in statement", type
);
1287 case ICV_THIRD_IN_FOR
:
1288 warning_at (loc
, 0, "indirection will not access object of "
1289 "incomplete type %qT in for increment "
1290 "expression", type
);
1296 /* Don't load the value if this is an implicit dereference, or if
1297 the type needs to be handled by ctors/dtors. */
1298 else if (is_volatile
&& is_reference
)
1300 if (complain
& tf_warning
)
1304 warning_at (loc
, 0, "conversion to void will not access "
1305 "object of type %qT", type
);
1307 case ICV_SECOND_OF_COND
:
1308 warning_at (loc
, 0, "implicit dereference will not access "
1309 "object of type %qT in second operand of "
1310 "conditional expression", type
);
1312 case ICV_THIRD_OF_COND
:
1313 warning_at (loc
, 0, "implicit dereference will not access "
1314 "object of type %qT in third operand of "
1315 "conditional expression", type
);
1317 case ICV_RIGHT_OF_COMMA
:
1318 warning_at (loc
, 0, "implicit dereference will not access "
1319 "object of type %qT in right operand of "
1320 "comma operator", type
);
1322 case ICV_LEFT_OF_COMMA
:
1323 warning_at (loc
, 0, "implicit dereference will not access "
1324 "object of type %qT in left operand of comma "
1328 warning_at (loc
, 0, "implicit dereference will not access "
1329 "object of type %qT in statement", type
);
1331 case ICV_THIRD_IN_FOR
:
1332 warning_at (loc
, 0, "implicit dereference will not access "
1333 "object of type %qT in for increment expression",
1340 else if (is_volatile
&& TREE_ADDRESSABLE (type
))
1342 if (complain
& tf_warning
)
1346 warning_at (loc
, 0, "conversion to void will not access "
1347 "object of non-trivially-copyable type %qT",
1350 case ICV_SECOND_OF_COND
:
1351 warning_at (loc
, 0, "indirection will not access object of "
1352 "non-trivially-copyable type %qT in second "
1353 "operand of conditional expression", type
);
1355 case ICV_THIRD_OF_COND
:
1356 warning_at (loc
, 0, "indirection will not access object of "
1357 "non-trivially-copyable type %qT in third "
1358 "operand of conditional expression", type
);
1360 case ICV_RIGHT_OF_COMMA
:
1361 warning_at (loc
, 0, "indirection will not access object of "
1362 "non-trivially-copyable type %qT in right "
1363 "operand of comma operator", type
);
1365 case ICV_LEFT_OF_COMMA
:
1366 warning_at (loc
, 0, "indirection will not access object of "
1367 "non-trivially-copyable type %qT in left "
1368 "operand of comma operator", type
);
1371 warning_at (loc
, 0, "indirection will not access object of "
1372 "non-trivially-copyable type %qT in statement",
1375 case ICV_THIRD_IN_FOR
:
1376 warning_at (loc
, 0, "indirection will not access object of "
1377 "non-trivially-copyable type %qT in for "
1378 "increment expression", type
);
1384 if (is_reference
|| !is_volatile
|| !is_complete
|| TREE_ADDRESSABLE (type
))
1386 /* Emit a warning (if enabled) when the "effect-less" INDIRECT_REF
1387 operation is stripped off. Note that we don't warn about
1388 - an expression with TREE_NO_WARNING set. (For an example of
1389 such expressions, see build_over_call in call.c.)
1390 - automatic dereferencing of references, since the user cannot
1391 control it. (See also warn_if_unused_value() in c-common.c.) */
1392 if (warn_unused_value
1393 && implicit
!= ICV_CAST
1394 && (complain
& tf_warning
)
1395 && !warning_suppressed_p (expr
, OPT_Wunused_value
)
1397 warning_at (loc
, OPT_Wunused_value
, "value computed is not used");
1398 expr
= TREE_OPERAND (expr
, 0);
1399 if (TREE_CODE (expr
) == CALL_EXPR
1400 && (complain
& tf_warning
))
1401 maybe_warn_nodiscard (expr
, implicit
);
1409 /* External variables might be incomplete. */
1410 tree type
= TREE_TYPE (expr
);
1411 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
1413 if (TYPE_VOLATILE (type
) && !is_complete
&& (complain
& tf_warning
))
1417 warning_at (loc
, 0, "conversion to void will not access "
1418 "object %qE of incomplete type %qT", expr
, type
);
1420 case ICV_SECOND_OF_COND
:
1421 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1422 "not be accessed in second operand of "
1423 "conditional expression", expr
, type
);
1425 case ICV_THIRD_OF_COND
:
1426 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1427 "not be accessed in third operand of "
1428 "conditional expression", expr
, type
);
1430 case ICV_RIGHT_OF_COMMA
:
1431 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1432 "not be accessed in right operand of comma operator",
1435 case ICV_LEFT_OF_COMMA
:
1436 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1437 "not be accessed in left operand of comma operator",
1441 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1442 "not be accessed in statement", expr
, type
);
1444 case ICV_THIRD_IN_FOR
:
1445 warning_at (loc
, 0, "variable %qE of incomplete type %qT will "
1446 "not be accessed in for increment expression",
1457 /* Don't bother with the temporary object returned from a function if
1458 we don't use it, don't need to destroy it, and won't abort in
1459 assign_temp. We'll still
1460 allocate space for it in expand_call or declare_return_variable,
1461 but we don't need to track it through all the tree phases. */
1462 if (TARGET_EXPR_IMPLICIT_P (expr
)
1463 && !TREE_ADDRESSABLE (TREE_TYPE (expr
)))
1465 tree init
= TARGET_EXPR_INITIAL (expr
);
1466 if (TREE_CODE (init
) == AGGR_INIT_EXPR
1467 && !AGGR_INIT_VIA_CTOR_P (init
))
1469 tree fn
= AGGR_INIT_EXPR_FN (init
);
1470 expr
= build_call_array_loc (input_location
,
1471 TREE_TYPE (TREE_TYPE
1474 aggr_init_expr_nargs (init
),
1475 AGGR_INIT_EXPR_ARGP (init
));
1478 if (complain
& tf_warning
)
1479 maybe_warn_nodiscard (expr
, implicit
);
1484 expr
= resolve_nondeduced_context (expr
, complain
);
1488 if (TREE_CODE (probe
) == ADDR_EXPR
)
1489 probe
= TREE_OPERAND (expr
, 0);
1490 if (type_unknown_p (probe
))
1492 /* [over.over] enumerates the places where we can take the address
1493 of an overloaded function, and this is not one of them. */
1494 if (complain
& tf_error
)
1498 error_at (loc
, "conversion to void "
1499 "cannot resolve address of overloaded function");
1501 case ICV_SECOND_OF_COND
:
1502 error_at (loc
, "second operand of conditional expression "
1503 "cannot resolve address of overloaded function");
1505 case ICV_THIRD_OF_COND
:
1506 error_at (loc
, "third operand of conditional expression "
1507 "cannot resolve address of overloaded function");
1509 case ICV_RIGHT_OF_COMMA
:
1510 error_at (loc
, "right operand of comma operator "
1511 "cannot resolve address of overloaded function");
1513 case ICV_LEFT_OF_COMMA
:
1514 error_at (loc
, "left operand of comma operator "
1515 "cannot resolve address of overloaded function");
1518 error_at (loc
, "statement "
1519 "cannot resolve address of overloaded function");
1521 case ICV_THIRD_IN_FOR
:
1522 error_at (loc
, "for increment expression "
1523 "cannot resolve address of overloaded function");
1527 return error_mark_node
;
1530 else if (implicit
!= ICV_CAST
&& probe
== expr
&& is_overloaded_fn (probe
))
1532 /* Only warn when there is no &. */
1533 if (complain
& tf_warning
)
1536 case ICV_SECOND_OF_COND
:
1537 warning_at (loc
, OPT_Waddress
,
1538 "second operand of conditional expression "
1539 "is a reference, not call, to function %qE", expr
);
1541 case ICV_THIRD_OF_COND
:
1542 warning_at (loc
, OPT_Waddress
,
1543 "third operand of conditional expression "
1544 "is a reference, not call, to function %qE", expr
);
1546 case ICV_RIGHT_OF_COMMA
:
1547 warning_at (loc
, OPT_Waddress
,
1548 "right operand of comma operator "
1549 "is a reference, not call, to function %qE", expr
);
1551 case ICV_LEFT_OF_COMMA
:
1552 warning_at (loc
, OPT_Waddress
,
1553 "left operand of comma operator "
1554 "is a reference, not call, to function %qE", expr
);
1557 warning_at (loc
, OPT_Waddress
,
1558 "statement is a reference, not call, to function %qE",
1561 case ICV_THIRD_IN_FOR
:
1562 warning_at (loc
, OPT_Waddress
,
1563 "for increment expression "
1564 "is a reference, not call, to function %qE", expr
);
1570 if (TREE_CODE (expr
) == COMPONENT_REF
)
1571 expr
= TREE_OPERAND (expr
, 0);
1575 if (expr
!= error_mark_node
&& !VOID_TYPE_P (TREE_TYPE (expr
)))
1577 if (implicit
!= ICV_CAST
1578 && warn_unused_value
1579 && !warning_suppressed_p (expr
, OPT_Wunused_value
)
1580 && !processing_template_decl
1581 && !cp_unevaluated_operand
1582 && (complain
& tf_warning
))
1584 /* The middle end does not warn about expressions that have
1585 been explicitly cast to void, so we must do so here. */
1586 if (!TREE_SIDE_EFFECTS (expr
))
1590 case ICV_SECOND_OF_COND
:
1591 warning_at (loc
, OPT_Wunused_value
,
1592 "second operand of conditional expression "
1595 case ICV_THIRD_OF_COND
:
1596 warning_at (loc
, OPT_Wunused_value
,
1597 "third operand of conditional expression "
1600 case ICV_RIGHT_OF_COMMA
:
1601 warning_at (loc
, OPT_Wunused_value
,
1602 "right operand of comma operator has no effect");
1604 case ICV_LEFT_OF_COMMA
:
1605 warning_at (loc
, OPT_Wunused_value
,
1606 "left operand of comma operator has no effect");
1609 warning_at (loc
, OPT_Wunused_value
,
1610 "statement has no effect");
1612 case ICV_THIRD_IN_FOR
:
1613 warning_at (loc
, OPT_Wunused_value
,
1614 "for increment expression has no effect");
1623 /* We might like to warn about (say) "(int) f()", as the
1624 cast has no effect, but the compiler itself will
1625 generate implicit conversions under some
1626 circumstances. (For example a block copy will be
1627 turned into a call to "__builtin_memcpy", with a
1628 conversion of the return value to an appropriate
1629 type.) So, to avoid false positives, we strip
1630 conversions. Do not use STRIP_NOPs because it will
1631 not strip conversions to "void", as that is not a
1632 mode-preserving conversion. */
1633 while (TREE_CODE (e
) == NOP_EXPR
)
1634 e
= TREE_OPERAND (e
, 0);
1636 enum tree_code code
= TREE_CODE (e
);
1637 enum tree_code_class tclass
= TREE_CODE_CLASS (code
);
1638 if (tclass
== tcc_comparison
1639 || tclass
== tcc_unary
1640 || tclass
== tcc_binary
1641 || code
== VEC_PERM_EXPR
1642 || code
== VEC_COND_EXPR
)
1643 warn_if_unused_value (e
, loc
);
1646 expr
= build1 (CONVERT_EXPR
, void_type_node
, expr
);
1648 if (! TREE_SIDE_EFFECTS (expr
))
1653 /* Create an expression whose value is that of EXPR,
1654 converted to type TYPE. The TREE_TYPE of the value
1655 is always TYPE. This function implements all reasonable
1656 conversions; callers should filter out those that are
1657 not permitted by the language being compiled.
1659 Most of this routine is from build_reinterpret_cast.
1661 The back end cannot call cp_convert (what was convert) because
1662 conversions to/from basetypes may involve memory references
1663 (vbases) and adding or subtracting small values (multiple
1664 inheritance), but it calls convert from the constant folding code
1665 on subtrees of already built trees after it has ripped them apart.
1667 Also, if we ever support range variables, we'll probably also have to
1668 do a little bit more work. */
1671 convert (tree type
, tree expr
)
1675 if (type
== error_mark_node
|| expr
== error_mark_node
)
1676 return error_mark_node
;
1678 intype
= TREE_TYPE (expr
);
1680 if (INDIRECT_TYPE_P (type
) && INDIRECT_TYPE_P (intype
))
1681 return build_nop (type
, expr
);
1683 return ocp_convert (type
, expr
, CONV_BACKEND_CONVERT
,
1684 LOOKUP_NORMAL
|LOOKUP_NO_CONVERSION
,
1685 tf_warning_or_error
);
1688 /* Like cp_convert, except permit conversions to take place which
1689 are not normally allowed due to access restrictions
1690 (such as conversion from sub-type to private super-type). */
1693 convert_force (tree type
, tree expr
, int convtype
, tsubst_flags_t complain
)
1696 enum tree_code code
= TREE_CODE (type
);
1698 if (code
== REFERENCE_TYPE
)
1699 return convert_to_reference (type
, e
, CONV_C_CAST
, 0,
1700 NULL_TREE
, complain
);
1702 if (code
== POINTER_TYPE
)
1703 return convert_to_pointer_force (type
, e
, complain
);
1705 /* From typeck.c convert_for_assignment */
1706 if (((TYPE_PTR_P (TREE_TYPE (e
)) && TREE_CODE (e
) == ADDR_EXPR
1707 && TREE_CODE (TREE_TYPE (TREE_TYPE (e
))) == METHOD_TYPE
)
1708 || integer_zerop (e
)
1709 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e
)))
1710 && TYPE_PTRMEMFUNC_P (type
))
1711 /* compatible pointer to member functions. */
1712 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), e
, 1,
1713 /*c_cast_p=*/1, complain
);
1715 return ocp_convert (type
, e
, CONV_C_CAST
|convtype
, LOOKUP_NORMAL
, complain
);
1718 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1719 exists, return the attempted conversion. This may
1720 return ERROR_MARK_NODE if the conversion is not
1721 allowed (references private members, etc).
1722 If no conversion exists, NULL_TREE is returned.
1724 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1725 object parameter, or by the second standard conversion sequence if
1726 that doesn't do it. This will probably wait for an overloading rewrite.
1730 build_type_conversion (tree xtype
, tree expr
)
1732 /* C++: check to see if we can convert this aggregate type
1733 into the required type. */
1734 return build_user_type_conversion (xtype
, expr
, LOOKUP_NORMAL
,
1735 tf_warning_or_error
);
1738 /* Convert the given EXPR to one of a group of types suitable for use in an
1739 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1740 which indicates which types are suitable. If COMPLAIN is true, complain
1741 about ambiguity; otherwise, the caller will deal with it. */
1744 build_expr_type_conversion (int desires
, tree expr
, bool complain
)
1746 tree basetype
= TREE_TYPE (expr
);
1747 tree conv
= NULL_TREE
;
1748 tree winner
= NULL_TREE
;
1750 if (null_node_p (expr
)
1751 && (desires
& WANT_INT
)
1752 && !(desires
& WANT_NULL
))
1755 expansion_point_location_if_in_system_header (input_location
);
1757 warning_at (loc
, OPT_Wconversion_null
,
1758 "converting NULL to non-pointer type");
1761 if (basetype
== error_mark_node
)
1762 return error_mark_node
;
1764 if (! MAYBE_CLASS_TYPE_P (basetype
))
1765 switch (TREE_CODE (basetype
))
1768 if ((desires
& WANT_NULL
) && null_ptr_cst_p (expr
))
1773 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1775 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1777 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1779 return (desires
& WANT_POINTER
) ? expr
: NULL_TREE
;
1783 return (desires
& WANT_POINTER
) ? decay_conversion (expr
,
1784 tf_warning_or_error
)
1788 if (!gnu_vector_type_p (basetype
))
1792 if ((desires
& WANT_VECTOR_OR_COMPLEX
) == 0)
1794 switch (TREE_CODE (TREE_TYPE (basetype
)))
1798 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1800 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1802 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1811 /* The code for conversions from class type is currently only used for
1812 delete expressions. Other expressions are handled by build_new_op. */
1813 if (!complete_type_or_maybe_complain (basetype
, expr
, complain
))
1814 return error_mark_node
;
1815 if (!TYPE_HAS_CONVERSION (basetype
))
1818 for (conv
= lookup_conversions (basetype
); conv
; conv
= TREE_CHAIN (conv
))
1822 tree cand
= TREE_VALUE (conv
);
1823 cand
= OVL_FIRST (cand
);
1825 if (winner
&& winner
== cand
)
1828 if (DECL_NONCONVERTING_P (cand
))
1831 candidate
= non_reference (TREE_TYPE (TREE_TYPE (cand
)));
1833 switch (TREE_CODE (candidate
))
1837 win
= (desires
& WANT_INT
); break;
1839 win
= (desires
& WANT_ENUM
); break;
1841 win
= (desires
& WANT_FLOAT
); break;
1843 win
= (desires
& WANT_POINTER
); break;
1847 if ((desires
& WANT_VECTOR_OR_COMPLEX
) == 0)
1849 switch (TREE_CODE (TREE_TYPE (candidate
)))
1853 win
= (desires
& WANT_INT
); break;
1855 win
= (desires
& WANT_ENUM
); break;
1857 win
= (desires
& WANT_FLOAT
); break;
1864 /* A wildcard could be instantiated to match any desired
1865 type, but we can't deduce the template argument. */
1866 if (WILDCARD_TYPE_P (candidate
))
1873 if (TREE_CODE (cand
) == TEMPLATE_DECL
)
1876 error ("default type conversion cannot deduce template"
1877 " argument for %qD", cand
);
1878 return error_mark_node
;
1884 = non_reference (TREE_TYPE (TREE_TYPE (winner
)));
1886 if (!same_type_ignoring_top_level_qualifiers_p (winner_type
,
1891 error ("ambiguous default type conversion from %qT",
1893 inform (input_location
,
1894 " candidate conversions include %qD and %qD",
1897 return error_mark_node
;
1907 tree type
= non_reference (TREE_TYPE (TREE_TYPE (winner
)));
1908 return build_user_type_conversion (type
, expr
, LOOKUP_NORMAL
,
1909 tf_warning_or_error
);
1915 /* Implements integral promotion (4.1) and float->double promotion. */
1918 type_promotes_to (tree type
)
1922 if (type
== error_mark_node
)
1923 return error_mark_node
;
1925 type
= TYPE_MAIN_VARIANT (type
);
1927 /* Check for promotions of target-defined types first. */
1928 promoted_type
= targetm
.promoted_type (type
);
1930 return promoted_type
;
1932 /* bool always promotes to int (not unsigned), even if it's the same
1934 if (TREE_CODE (type
) == BOOLEAN_TYPE
)
1935 type
= integer_type_node
;
1937 /* Normally convert enums to int, but convert wide enums to something
1938 wider. Scoped enums don't promote, but pretend they do for backward
1939 ABI bug compatibility wrt varargs. */
1940 else if (TREE_CODE (type
) == ENUMERAL_TYPE
1941 || type
== char8_type_node
1942 || type
== char16_type_node
1943 || type
== char32_type_node
1944 || type
== wchar_type_node
)
1948 if (TREE_CODE (type
) == ENUMERAL_TYPE
)
1950 prom
= ENUM_UNDERLYING_TYPE (prom
);
1951 if (!ENUM_IS_SCOPED (type
)
1952 && ENUM_FIXED_UNDERLYING_TYPE_P (type
))
1954 /* ISO C++17, 7.6/4. A prvalue of an unscoped enumeration type
1955 whose underlying type is fixed (10.2) can be converted to a
1956 prvalue of its underlying type. Moreover, if integral promotion
1957 can be applied to its underlying type, a prvalue of an unscoped
1958 enumeration type whose underlying type is fixed can also be
1959 converted to a prvalue of the promoted underlying type. */
1960 return type_promotes_to (prom
);
1964 int precision
= MAX (TYPE_PRECISION (type
),
1965 TYPE_PRECISION (integer_type_node
));
1966 tree totype
= c_common_type_for_size (precision
, 0);
1967 if (TYPE_UNSIGNED (prom
)
1968 && ! int_fits_type_p (TYPE_MAX_VALUE (prom
), totype
))
1969 prom
= c_common_type_for_size (precision
, 1);
1972 if (SCOPED_ENUM_P (type
))
1974 if (abi_version_crosses (6)
1975 && TYPE_MODE (prom
) != TYPE_MODE (type
))
1976 warning (OPT_Wabi
, "scoped enum %qT passed through %<...%> as "
1977 "%qT before %<-fabi-version=6%>, %qT after",
1978 type
, prom
, ENUM_UNDERLYING_TYPE (type
));
1979 if (!abi_version_at_least (6))
1985 else if (c_promoting_integer_type_p (type
))
1987 /* Retain unsignedness if really not getting bigger. */
1988 if (TYPE_UNSIGNED (type
)
1989 && TYPE_PRECISION (type
) == TYPE_PRECISION (integer_type_node
))
1990 type
= unsigned_type_node
;
1992 type
= integer_type_node
;
1994 else if (type
== float_type_node
)
1995 type
= double_type_node
;
2000 /* The routines below this point are carefully written to conform to
2001 the standard. They use the same terminology, and follow the rules
2002 closely. Although they are used only in pt.c at the moment, they
2003 should presumably be used everywhere in the future. */
2005 /* True iff EXPR can be converted to TYPE via a qualification conversion.
2006 Callers should check for identical types before calling this function. */
2009 can_convert_qual (tree type
, tree expr
)
2011 tree expr_type
= TREE_TYPE (expr
);
2012 gcc_assert (!same_type_p (type
, expr_type
));
2014 /* A function pointer conversion also counts as a Qualification Adjustment
2015 under [over.ics.scs]. */
2016 if (fnptr_conv_p (type
, expr_type
))
2019 if (TYPE_PTR_P (type
) && TYPE_PTR_P (expr_type
))
2020 return comp_ptr_ttypes (TREE_TYPE (type
), TREE_TYPE (expr_type
));
2021 else if (TYPE_PTRMEM_P (type
) && TYPE_PTRMEM_P (expr_type
))
2022 return (same_type_p (TYPE_PTRMEM_CLASS_TYPE (type
),
2023 TYPE_PTRMEM_CLASS_TYPE (expr_type
))
2024 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type
),
2025 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type
)));
2030 /* Attempt to perform qualification conversions on EXPR to convert it
2031 to TYPE. Return the resulting expression, or error_mark_node if
2032 the conversion was impossible. Since this is only used by
2033 convert_nontype_argument, we fold the conversion. */
2036 perform_qualification_conversions (tree type
, tree expr
)
2040 expr_type
= TREE_TYPE (expr
);
2042 if (same_type_p (type
, expr_type
))
2044 else if (can_convert_qual (type
, expr
))
2045 return cp_fold_convert (type
, expr
);
2047 return error_mark_node
;
2050 /* True iff T is a transaction-safe function type. */
2053 tx_safe_fn_type_p (tree t
)
2055 if (!FUNC_OR_METHOD_TYPE_P (t
))
2057 return !!lookup_attribute ("transaction_safe", TYPE_ATTRIBUTES (t
));
2060 /* Return the transaction-unsafe variant of transaction-safe function type
2064 tx_unsafe_fn_variant (tree t
)
2066 gcc_assert (tx_safe_fn_type_p (t
));
2067 tree attrs
= remove_attribute ("transaction_safe",
2068 TYPE_ATTRIBUTES (t
));
2069 return cp_build_type_attribute_variant (t
, attrs
);
2072 /* Return true iff FROM can convert to TO by a transaction-safety
2076 can_convert_tx_safety (tree to
, tree from
)
2078 return (flag_tm
&& tx_safe_fn_type_p (from
)
2079 && same_type_p (to
, tx_unsafe_fn_variant (from
)));
2082 /* Return true iff FROM can convert to TO by dropping noexcept.
2083 This is just a subroutine of of fnptr_conv_p. */
2086 noexcept_conv_p (tree to
, tree from
)
2088 if (!flag_noexcept_type
)
2091 if (TREE_CODE (to
) != TREE_CODE (from
))
2093 if (!FUNC_OR_METHOD_TYPE_P (from
))
2095 if (!type_throw_all_p (to
)
2096 || type_throw_all_p (from
))
2098 tree v
= build_exception_variant (from
, NULL_TREE
);
2099 return same_type_p (to
, v
);
2102 /* Return true iff FROM can convert to TO by a function pointer conversion. */
2105 fnptr_conv_p (tree to
, tree from
)
2109 if (TYPE_PTRMEMFUNC_P (t
)
2110 && TYPE_PTRMEMFUNC_P (f
))
2112 t
= TYPE_PTRMEMFUNC_FN_TYPE (t
);
2113 f
= TYPE_PTRMEMFUNC_FN_TYPE (f
);
2115 if (INDIRECT_TYPE_P (t
)
2116 && INDIRECT_TYPE_P (f
))
2122 return (noexcept_conv_p (t
, f
)
2123 || can_convert_tx_safety (t
, f
));
2126 /* Return FN with any NOP_EXPRs stripped that represent function pointer
2127 conversions or conversions to the same type. */
2130 strip_fnptr_conv (tree fn
)
2132 while (TREE_CODE (fn
) == NOP_EXPR
)
2134 tree op
= TREE_OPERAND (fn
, 0);
2135 tree ft
= TREE_TYPE (fn
);
2136 tree ot
= TREE_TYPE (op
);
2137 if (same_type_p (ft
, ot
)
2138 || fnptr_conv_p (ft
, ot
))