1 /* Language-level data type conversion for GNU C++.
2 Copyright (C) 1987-2022 Free Software Foundation, Inc.
3 Hacked by Michael Tiemann (tiemann@cygnus.com)
4
5 This file is part of GCC.
6
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)
10 any later version.
11
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.
16
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/>. */
20
21
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. */
26
27 #include "config.h"
28 #include "system.h"
29 #include "coretypes.h"
30 #include "target.h"
31 #include "cp-tree.h"
32 #include "stor-layout.h"
33 #include "flags.h"
34 #include "intl.h"
35 #include "convert.h"
36 #include "stringpool.h"
37 #include "attribs.h"
38 #include "escaped_string.h"
39
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);
44
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.
48
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.
52
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.cc, convert_to_integer[_maybe_fold].
56 In c-typeck.cc, build_binary_op_nodefault (boolean ops),
57 and c_common_truthvalue_conversion.
58 In expr.cc: expand_expr, for operands of a MULT_EXPR.
59 In fold-const.cc: fold.
60 In tree.cc: get_narrower and get_unwidened.
61
62 C++: in multiple-inheritance, converting between pointers may involve
63 adjusting them by a delta stored within the class definition. */
64
65 /* Subroutines of `convert'. */
66
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
70 else convert blindly
71 else if converting class, pass off to build_type_conversion
72 else try C-style pointer conversion. */
73
74 static tree
cp_convert_to_pointer(tree type,tree expr,bool dofold,tsubst_flags_t complain)75 cp_convert_to_pointer (tree type, tree expr, bool dofold,
76 tsubst_flags_t complain)
77 {
78 tree intype = TREE_TYPE (expr);
79 enum tree_code form;
80 tree rval;
81 location_t loc = cp_expr_loc_or_input_loc (expr);
82
83 if (intype == error_mark_node)
84 return error_mark_node;
85
86 if (MAYBE_CLASS_TYPE_P (intype))
87 {
88 intype = complete_type (intype);
89 if (!COMPLETE_TYPE_P (intype))
90 {
91 if (complain & tf_error)
92 error_at (loc, "cannot convert from incomplete type %qH to %qI",
93 intype, type);
94 return error_mark_node;
95 }
96
97 rval = build_type_conversion (type, expr);
98 if (rval)
99 {
100 if ((complain & tf_error)
101 && rval == error_mark_node)
102 error_at (loc, "conversion of %qE from %qH to %qI is ambiguous",
103 expr, intype, type);
104 return rval;
105 }
106 }
107
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))))
112 {
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);
119 }
120
121 if (expr == error_mark_node)
122 return error_mark_node;
123
124 form = TREE_CODE (intype);
125
126 if (INDIRECT_TYPE_P (intype))
127 {
128 intype = TYPE_MAIN_VARIANT (intype);
129
130 if (TYPE_MAIN_VARIANT (type) != intype
131 && TYPE_PTR_P (type)
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)
136 {
137 enum tree_code code = PLUS_EXPR;
138 tree binfo;
139 tree intype_class;
140 tree type_class;
141 bool same_p;
142
143 intype_class = TREE_TYPE (intype);
144 type_class = TREE_TYPE (type);
145
146 same_p = same_type_p (TYPE_MAIN_VARIANT (intype_class),
147 TYPE_MAIN_VARIANT (type_class));
148 binfo = NULL_TREE;
149 /* Try derived to base conversion. */
150 if (!same_p)
151 binfo = lookup_base (intype_class, type_class, ba_check,
152 NULL, complain);
153 if (!same_p && !binfo)
154 {
155 /* Try base to derived conversion. */
156 binfo = lookup_base (type_class, intype_class, ba_check,
157 NULL, complain);
158 code = MINUS_EXPR;
159 }
160 if (binfo == error_mark_node)
161 return error_mark_node;
162 if (binfo || same_p)
163 {
164 if (binfo)
165 expr = build_base_path (code, expr, binfo, 0, complain);
166 /* Add any qualifier conversions. */
167 return build_nop (type, expr);
168 }
169 }
170
171 if (TYPE_PTRMEMFUNC_P (type))
172 {
173 if (complain & tf_error)
174 error_at (loc, "cannot convert %qE from type %qH to type %qI",
175 expr, intype, type);
176 return error_mark_node;
177 }
178
179 return build_nop (type, expr);
180 }
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))
186 {
187 if (!warn_pmf2ptr)
188 {
189 if (TREE_CODE (expr) == PTRMEM_CST)
190 return cp_convert_to_pointer (type, PTRMEM_CST_MEMBER (expr),
191 dofold, complain);
192 else if (TREE_CODE (expr) == OFFSET_REF)
193 {
194 tree object = TREE_OPERAND (expr, 0);
195 return get_member_function_from_ptrfunc (&object,
196 TREE_OPERAND (expr, 1),
197 complain);
198 }
199 }
200 if (complain & tf_error)
201 error_at (loc, "cannot convert %qE from type %qH to type %qI",
202 expr, intype, type);
203 return error_mark_node;
204 }
205
206 if (null_ptr_cst_p (expr))
207 {
208 if (TYPE_PTRMEMFUNC_P (type))
209 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0,
210 /*c_cast_p=*/false, complain);
211
212 if (complain & tf_warning)
213 maybe_warn_zero_as_null_pointer_constant (expr, loc);
214
215 /* A NULL pointer-to-data-member is represented by -1, not by
216 zero. */
217 tree val = (TYPE_PTRDATAMEM_P (type)
218 ? build_int_cst_type (type, -1)
219 : build_int_cst (type, 0));
220
221 return (TREE_SIDE_EFFECTS (expr)
222 ? build2 (COMPOUND_EXPR, type, expr, val) : val);
223 }
224 else if (TYPE_PTRMEM_P (type) && INTEGRAL_CODE_P (form))
225 {
226 if (complain & tf_error)
227 error_at (loc, "invalid conversion from %qH to %qI", intype, type);
228 return error_mark_node;
229 }
230
231 if (INTEGRAL_CODE_P (form))
232 {
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,
236 complain);
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
239 as a pointer. */
240 gcc_assert (GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (TREE_TYPE (expr)))
241 == GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (type)));
242
243 /* FIXME needed because convert_to_pointer_maybe_fold still folds
244 conversion of constants. */
245 if (!dofold)
246 return build1 (CONVERT_EXPR, type, expr);
247
248 return convert_to_pointer_maybe_fold (type, expr, dofold);
249 }
250
251 if (type_unknown_p (expr))
252 return instantiate_type (type, expr, complain);
253
254 if (complain & tf_error)
255 error_at (loc, "cannot convert %qE from type %qH to type %qI",
256 expr, intype, type);
257 return error_mark_node;
258 }
259
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). */
263
264 static tree
convert_to_pointer_force(tree type,tree expr,tsubst_flags_t complain)265 convert_to_pointer_force (tree type, tree expr, tsubst_flags_t complain)
266 {
267 tree intype = TREE_TYPE (expr);
268 enum tree_code form = TREE_CODE (intype);
269
270 if (form == POINTER_TYPE)
271 {
272 intype = TYPE_MAIN_VARIANT (intype);
273
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)
279 {
280 enum tree_code code = PLUS_EXPR;
281 tree binfo;
282
283 binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
284 ba_unique, NULL, complain);
285 if (!binfo)
286 {
287 binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
288 ba_unique, NULL, complain);
289 code = MINUS_EXPR;
290 }
291 if (binfo == error_mark_node)
292 return error_mark_node;
293 if (binfo)
294 {
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)),
300 TREE_TYPE (type)))
301 expr = build_nop (type, expr);
302 return expr;
303 }
304 }
305 }
306
307 return cp_convert_to_pointer (type, expr, /*fold*/false, complain);
308 }
309
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.
313
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. */
317
318 static tree
build_up_reference(tree type,tree arg,int flags,tree decl,tsubst_flags_t complain)319 build_up_reference (tree type, tree arg, int flags, tree decl,
320 tsubst_flags_t complain)
321 {
322 tree rval;
323 tree argtype = TREE_TYPE (arg);
324 tree target_type = TREE_TYPE (type);
325
326 gcc_assert (TYPE_REF_P (type));
327
328 if ((flags & DIRECT_BIND) && ! lvalue_p (arg))
329 {
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. */
332 tree targ = arg;
333
334 arg = make_temporary_var_for_ref_to_temp (decl, target_type);
335
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);
340 }
341 else if (!(flags & DIRECT_BIND) && ! obvalue_p (arg))
342 return get_target_expr_sfinae (arg, complain);
343
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;
350
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))
355 {
356 /* We go through lookup_base for the access control. */
357 tree binfo = lookup_base (argtype, target_type, ba_check,
358 NULL, complain);
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);
364 }
365 else
366 rval
367 = convert_to_pointer_force (build_pointer_type (target_type),
368 rval, complain);
369 return build_nop (type, rval);
370 }
371
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
374 for diagnostics.
375
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. */
379
380 static void
diagnose_ref_binding(location_t loc,tree reftype,tree intype,tree decl)381 diagnose_ref_binding (location_t loc, tree reftype, tree intype, tree decl)
382 {
383 tree ttl = TREE_TYPE (reftype);
384
385 if (!TYPE_REF_IS_RVALUE (reftype)
386 && !CP_TYPE_CONST_NON_VOLATILE_P (ttl))
387 {
388 const char *msg;
389
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");
396 else if (decl)
397 msg = G_("initialization of non-const reference type %q#T from "
398 "rvalue of type %qT");
399 else
400 msg = G_("conversion to non-const reference type %q#T from "
401 "rvalue of type %qT");
402
403 permerror (loc, msg, reftype, intype);
404 }
405 }
406
407 /* For C++: Only need to do one-level references, but cannot
408 get tripped up on signed/unsigned differences.
409
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. */
413
414 tree
convert_to_reference(tree reftype,tree expr,int convtype,int flags,tree decl,tsubst_flags_t complain)415 convert_to_reference (tree reftype, tree expr, int convtype,
416 int flags, tree decl, tsubst_flags_t complain)
417 {
418 tree type = TYPE_MAIN_VARIANT (TREE_TYPE (reftype));
419 tree intype;
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);
424
425 if (TREE_CODE (type) == FUNCTION_TYPE
426 && TREE_TYPE (expr) == unknown_type_node)
427 expr = instantiate_type (type, expr, complain);
428
429 if (expr == error_mark_node)
430 return error_mark_node;
431
432 intype = TREE_TYPE (expr);
433
434 gcc_assert (!TYPE_REF_P (intype));
435 gcc_assert (TYPE_REF_P (reftype));
436
437 intype = TYPE_MAIN_VARIANT (intype);
438
439 can_convert_intype_to_type = can_convert_standard (type, intype, complain);
440
441 if (!can_convert_intype_to_type
442 && (convtype & CONV_IMPLICIT) && MAYBE_CLASS_TYPE_P (intype)
443 && ! (flags & LOOKUP_NO_CONVERSION))
444 {
445 /* Look for a user-defined conversion to lvalue that we can use. */
446
447 rval_as_conversion
448 = build_type_conversion (reftype, expr);
449
450 if (rval_as_conversion && rval_as_conversion != error_mark_node
451 && lvalue_p (rval_as_conversion))
452 {
453 expr = rval_as_conversion;
454 rval_as_conversion = NULL_TREE;
455 intype = type;
456 can_convert_intype_to_type = 1;
457 }
458 }
459
460 if (((convtype & CONV_STATIC)
461 && can_convert_standard (intype, type, complain))
462 || ((convtype & CONV_IMPLICIT) && can_convert_intype_to_type))
463 {
464 {
465 tree ttl = TREE_TYPE (reftype);
466 tree ttr = lvalue_type (expr);
467
468 if ((complain & tf_error)
469 && ! lvalue_p (expr))
470 diagnose_ref_binding (loc, reftype, intype, decl);
471
472 if (! (convtype & CONV_CONST)
473 && !at_least_as_qualified_p (ttl, ttr))
474 {
475 if (complain & tf_error)
476 permerror (loc, "conversion from %qH to %qI discards qualifiers",
477 ttr, reftype);
478 else
479 return error_mark_node;
480 }
481 }
482
483 return build_up_reference (reftype, expr, flags, decl, complain);
484 }
485 else if ((convtype & CONV_REINTERPRET) && obvalue_p (expr))
486 {
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 */
491
492 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
493 meant. */
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",
499 intype, reftype);
500
501 rval = cp_build_addr_expr (expr, complain);
502 if (rval != error_mark_node)
503 rval = convert_force (build_pointer_type (TREE_TYPE (reftype)),
504 rval, 0, complain);
505 if (rval != error_mark_node)
506 rval = build1 (NOP_EXPR, reftype, rval);
507 }
508 else
509 {
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)
513 return rval;
514 if (complain & tf_error)
515 diagnose_ref_binding (loc, reftype, intype, decl);
516 rval = build_up_reference (reftype, rval, flags, decl, complain);
517 }
518
519 if (rval)
520 {
521 /* If we found a way to convert earlier, then use it. */
522 return rval;
523 }
524
525 if (complain & tf_error)
526 error_at (loc, "cannot convert type %qH to type %qI", intype, reftype);
527
528 return error_mark_node;
529 }
530
531 /* We are using a reference VAL for its value. Bash that reference all the
532 way down to its lowest form. */
533
534 tree
convert_from_reference(tree val)535 convert_from_reference (tree val)
536 {
537 if (TREE_TYPE (val)
538 && TYPE_REF_P (TREE_TYPE (val)))
539 {
540 tree t = TREE_TYPE (TREE_TYPE (val));
541 tree ref = build1 (INDIRECT_REF, t, val);
542
543 mark_exp_read (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));
551 val = ref;
552 }
553
554 return val;
555 }
556
557 /* Really perform an lvalue-to-rvalue conversion, including copying an
558 argument of class type into a temporary. */
559
560 tree
force_rvalue(tree expr,tsubst_flags_t complain)561 force_rvalue (tree expr, tsubst_flags_t complain)
562 {
563 tree type = TREE_TYPE (expr);
564 if (MAYBE_CLASS_TYPE_P (type) && TREE_CODE (expr) != TARGET_EXPR)
565 {
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);
570 }
571 else
572 expr = decay_conversion (expr, complain);
573
574 return expr;
575 }
576
577
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
580 unchanged. */
581
582 static tree
ignore_overflows(tree expr,tree orig)583 ignore_overflows (tree expr, tree orig)
584 {
585 tree stripped_expr = tree_strip_any_location_wrapper (expr);
586 tree stripped_orig = tree_strip_any_location_wrapper (orig);
587
588 if (TREE_CODE (stripped_expr) == INTEGER_CST
589 && TREE_CODE (stripped_orig) == INTEGER_CST
590 && TREE_OVERFLOW (stripped_expr) != TREE_OVERFLOW (stripped_orig))
591 {
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));
596 }
597
598 return preserve_any_location_wrapper (stripped_expr, expr);
599 }
600
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. */
604
605 tree
cp_fold_convert(tree type,tree expr)606 cp_fold_convert (tree type, tree expr)
607 {
608 tree conv;
609 if (TREE_TYPE (expr) == type)
610 conv = expr;
611 else if (TREE_CODE (expr) == PTRMEM_CST
612 && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type),
613 PTRMEM_CST_CLASS (expr)))
614 {
615 /* Avoid wrapping a PTRMEM_CST in NOP_EXPR. */
616 conv = copy_node (expr);
617 TREE_TYPE (conv) = type;
618 }
619 else if (TYPE_PTRMEM_P (type))
620 {
621 conv = convert_ptrmem (type, expr, true, false,
622 tf_warning_or_error);
623 conv = cp_fully_fold (conv);
624 }
625 else
626 {
627 conv = fold_convert (type, expr);
628 conv = ignore_overflows (conv, expr);
629 }
630
631 if (TREE_CODE (expr) == TREE_CODE (conv))
632 copy_warning (conv, expr);
633
634 return conv;
635 }
636
637 /* C++ conversions, preference to static cast conversions. */
638
639 tree
cp_convert(tree type,tree expr,tsubst_flags_t complain)640 cp_convert (tree type, tree expr, tsubst_flags_t complain)
641 {
642 return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL, complain);
643 }
644
645 /* C++ equivalent of convert_and_check but using cp_convert as the
646 conversion function.
647
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. */
651
652 tree
cp_convert_and_check(tree type,tree expr,tsubst_flags_t complain)653 cp_convert_and_check (tree type, tree expr, tsubst_flags_t complain)
654 {
655 tree result;
656
657 if (TREE_TYPE (expr) == type)
658 return expr;
659 if (expr == error_mark_node)
660 return expr;
661 result = cp_convert (type, expr, complain);
662
663 if ((complain & tf_warning)
664 && c_inhibit_evaluation_warnings == 0)
665 {
666 tree folded = cp_fully_fold (expr);
667 tree folded_result;
668 if (folded == expr)
669 folded_result = result;
670 else
671 {
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);
676 }
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);
682 }
683
684 return result;
685 }
686
687 /* Conversion...
688
689 FLAGS indicates how we should behave. */
690
691 tree
ocp_convert(tree type,tree expr,int convtype,int flags,tsubst_flags_t complain)692 ocp_convert (tree type, tree expr, int convtype, int flags,
693 tsubst_flags_t complain)
694 {
695 tree e = expr;
696 enum tree_code code = TREE_CODE (type);
697 const char *invalid_conv_diag;
698 tree e1;
699 location_t loc = cp_expr_loc_or_input_loc (expr);
700 bool dofold = (convtype & CONV_FOLD);
701
702 if (error_operand_p (e) || type == error_mark_node)
703 return error_mark_node;
704
705 if (TREE_CODE (e) == COMPOUND_EXPR)
706 {
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))
711 return expr;
712 return build2_loc (EXPR_LOCATION (expr), COMPOUND_EXPR, TREE_TYPE (e),
713 TREE_OPERAND (expr, 0), e);
714 }
715
716 complete_type (type);
717 complete_type (TREE_TYPE (expr));
718
719 if ((invalid_conv_diag
720 = targetm.invalid_conversion (TREE_TYPE (expr), type)))
721 {
722 if (complain & tf_error)
723 error (invalid_conv_diag);
724 return error_mark_node;
725 }
726
727 /* FIXME remove when moving to c_fully_fold model. */
728 if (!CLASS_TYPE_P (type))
729 {
730 e = mark_rvalue_use (e);
731 tree v = scalar_constant_value (e);
732 if (!error_operand_p (v))
733 e = v;
734 }
735 if (error_operand_p (e))
736 return error_mark_node;
737
738 if (NULLPTR_TYPE_P (type) && null_ptr_cst_p (e))
739 {
740 if (complain & tf_warning)
741 maybe_warn_zero_as_null_pointer_constant (e, loc);
742
743 if (!TREE_SIDE_EFFECTS (e))
744 return nullptr_node;
745 }
746
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)))
750 {
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. */
759 return e;
760 /* For complex data types, we need to perform componentwise
761 conversion. */
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)
767 {
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;
772 return e;
773 }
774 else if (TREE_CODE (e) == CONSTRUCTOR)
775 {
776 gcc_assert (same_type_ignoring_top_level_qualifiers_p (type, etype));
777 TREE_TYPE (e) = type;
778 return e;
779 }
780 else
781 {
782 /* We shouldn't be treating objects of ADDRESSABLE type as
783 rvalues. */
784 gcc_assert (!TREE_ADDRESSABLE (type));
785 return build_nop (type, e);
786 }
787 }
788
789 e1 = targetm.convert_to_type (type, e);
790 if (e1)
791 return e1;
792
793 if (code == VOID_TYPE && (convtype & CONV_STATIC))
794 {
795 e = convert_to_void (e, ICV_CAST, complain);
796 return e;
797 }
798
799 if (INTEGRAL_CODE_P (code))
800 {
801 tree intype = TREE_TYPE (e);
802 tree converted;
803
804 if (TREE_CODE (type) == ENUMERAL_TYPE)
805 {
806 /* enum = enum, enum = int, enum = float, (enum)pointer are all
807 errors. */
808 if (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype)
809 || TREE_CODE (intype) == REAL_TYPE)
810 && ! (convtype & CONV_STATIC))
811 || TYPE_PTR_P (intype))
812 {
813 if (complain & tf_error)
814 permerror (loc, "conversion from %q#T to %q#T", intype, type);
815 else
816 return error_mark_node;
817 }
818
819 /* [expr.static.cast]
820
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
825 unspecified. */
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",
834 expr, type);
835 }
836 if (MAYBE_CLASS_TYPE_P (intype))
837 {
838 tree rval;
839 rval = build_type_conversion (type, e);
840 if (rval)
841 return rval;
842 if (complain & tf_error)
843 error_at (loc, "%q#T used where a %qT was expected", intype, type);
844 return error_mark_node;
845 }
846 if (code == BOOLEAN_TYPE)
847 {
848 if (VOID_TYPE_P (intype))
849 {
850 if (complain & tf_error)
851 error_at (loc,
852 "could not convert %qE from %<void%> to %<bool%>",
853 expr);
854 return error_mark_node;
855 }
856
857 if (VECTOR_TYPE_P (intype) && !gnu_vector_type_p (intype))
858 {
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;
863 }
864
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);
871 else
872 {
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);
878 }
879 }
880
881 converted = convert_to_integer_maybe_fold (type, e, dofold);
882
883 /* Ignore any integer overflow caused by the conversion. */
884 return ignore_overflows (converted, e);
885 }
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)
889 {
890 tree in_vtype = TREE_TYPE (e);
891 if (MAYBE_CLASS_TYPE_P (in_vtype))
892 {
893 tree ret_val;
894 ret_val = build_type_conversion (type, e);
895 if (ret_val)
896 return ret_val;
897 if (complain & tf_error)
898 error_at (loc, "%q#T used where a %qT was expected",
899 in_vtype, type);
900 return error_mark_node;
901 }
902 return convert_to_vector (type, rvalue (e));
903 }
904 if (code == REAL_TYPE || code == COMPLEX_TYPE)
905 {
906 if (MAYBE_CLASS_TYPE_P (TREE_TYPE (e)))
907 {
908 tree rval;
909 rval = build_type_conversion (type, e);
910 if (rval)
911 return rval;
912 else if (complain & tf_error)
913 error_at (loc,
914 "%q#T used where a floating-point value was expected",
915 TREE_TYPE (e));
916 }
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);
921 }
922
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))
927 {
928 tree dtype = TREE_TYPE (e);
929 tree ctor = NULL_TREE;
930
931 dtype = TYPE_MAIN_VARIANT (dtype);
932
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.
936
937 There may be some ambiguity between using a constructor
938 vs. using a type conversion operator when both apply. */
939
940 ctor = e;
941
942 if (abstract_virtuals_error_sfinae (NULL_TREE, type, complain))
943 return error_mark_node;
944
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);
953 else
954 {
955 releasing_vec ctor_vec (make_tree_vector_single (ctor));
956 ctor = build_special_member_call (NULL_TREE,
957 complete_ctor_identifier,
958 &ctor_vec,
959 type, flags, complain);
960 }
961 if (ctor)
962 return build_cplus_new (type, ctor, complain);
963 }
964
965 if (complain & tf_error)
966 {
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. */;
971 else
972 error_at (loc, "conversion from %qH to non-scalar type %qI requested",
973 TREE_TYPE (expr), type);
974 }
975 return error_mark_node;
976 }
977
978 /* If CALL is a call, return the callee; otherwise null. */
979
980 tree
cp_get_callee(tree call)981 cp_get_callee (tree call)
982 {
983 if (call == NULL_TREE)
984 return call;
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);
989 return NULL_TREE;
990 }
991
992 /* FN is the callee of a CALL_EXPR or AGGR_INIT_EXPR; return the FUNCTION_DECL
993 if we can. */
994
995 tree
cp_get_fndecl_from_callee(tree fn,bool fold)996 cp_get_fndecl_from_callee (tree fn, bool fold /* = true */)
997 {
998 if (fn == NULL_TREE)
999 return fn;
1000 if (TREE_CODE (fn) == FUNCTION_DECL)
1001 return fn;
1002 tree type = TREE_TYPE (fn);
1003 if (type == NULL_TREE || !INDIRECT_TYPE_P (type))
1004 return NULL_TREE;
1005 if (fold)
1006 fn = maybe_constant_init (fn);
1007 STRIP_NOPS (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)
1012 return fn;
1013 return NULL_TREE;
1014 }
1015
1016 /* Like get_callee_fndecl, but handles AGGR_INIT_EXPR as well and uses the
1017 constexpr machinery. */
1018
1019 tree
cp_get_callee_fndecl(tree call)1020 cp_get_callee_fndecl (tree call)
1021 {
1022 return cp_get_fndecl_from_callee (cp_get_callee (call));
1023 }
1024
1025 /* As above, but not using the constexpr machinery. */
1026
1027 tree
cp_get_callee_fndecl_nofold(tree call)1028 cp_get_callee_fndecl_nofold (tree call)
1029 {
1030 return cp_get_fndecl_from_callee (cp_get_callee (call), false);
1031 }
1032
1033 /* Subroutine of convert_to_void. Warn if we're discarding something with
1034 attribute [[nodiscard]]. */
1035
1036 static void
maybe_warn_nodiscard(tree expr,impl_conv_void implicit)1037 maybe_warn_nodiscard (tree expr, impl_conv_void implicit)
1038 {
1039 if (!warn_unused_result || c_inhibit_evaluation_warnings)
1040 return;
1041
1042 tree call = expr;
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);
1047 if (!callee)
1048 return;
1049
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);
1055
1056 tree rettype = TREE_TYPE (type);
1057 tree fn = cp_get_fndecl_from_callee (callee);
1058 tree attr;
1059 if (implicit != ICV_CAST && fn
1060 && (attr = lookup_attribute ("nodiscard", DECL_ATTRIBUTES (fn))))
1061 {
1062 escaped_string msg;
1063 tree args = TREE_VALUE (attr);
1064 if (args)
1065 msg.escape (TREE_STRING_POINTER (TREE_VALUE (args)));
1066 const char *format
1067 = (msg
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");
1076 }
1077 else if (implicit != ICV_CAST
1078 && (attr = lookup_attribute ("nodiscard", TYPE_ATTRIBUTES (rettype))))
1079 {
1080 escaped_string msg;
1081 tree args = TREE_VALUE (attr);
1082 if (args)
1083 msg.escape (TREE_STRING_POINTER (TREE_VALUE (args)));
1084 const char *format
1085 = (msg
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))
1093 {
1094 if (fn)
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);
1099 }
1100 }
1101 else if (TREE_CODE (expr) == TARGET_EXPR
1102 && lookup_attribute ("warn_unused_result", TYPE_ATTRIBUTES (type)))
1103 {
1104 /* The TARGET_EXPR confuses do_warn_unused_result into thinking that the
1105 result is used, so handle that case here. */
1106 if (fn)
1107 {
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%>",
1112 fn))
1113 inform (DECL_SOURCE_LOCATION (fn), "declared here");
1114 }
1115 else
1116 warning_at (loc, OPT_Wunused_result,
1117 "ignoring return value of function "
1118 "declared with attribute %<warn_unused_result%>");
1119 }
1120 }
1121
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.
1136
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. */
1140
1141 tree
convert_to_void(tree expr,impl_conv_void implicit,tsubst_flags_t complain)1142 convert_to_void (tree expr, impl_conv_void implicit, tsubst_flags_t complain)
1143 {
1144 location_t loc = cp_expr_loc_or_input_loc (expr);
1145
1146 if (expr == error_mark_node
1147 || TREE_TYPE (expr) == error_mark_node)
1148 return error_mark_node;
1149
1150 expr = maybe_undo_parenthesized_ref (expr);
1151
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);
1156
1157 if (!TREE_TYPE (expr))
1158 return expr;
1159 if (invalid_nonstatic_memfn_p (loc, expr, complain))
1160 return error_mark_node;
1161 if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR)
1162 {
1163 if (complain & tf_error)
1164 error_at (loc, "pseudo-destructor is not called");
1165 return error_mark_node;
1166 }
1167
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);
1172
1173 if (VOID_TYPE_P (TREE_TYPE (expr)))
1174 return expr;
1175 switch (TREE_CODE (expr))
1176 {
1177 case COND_EXPR:
1178 {
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)
1187 {
1188 if (op1)
1189 new_op1 = convert_to_void (op1, ICV_SECOND_OF_COND, complain);
1190 new_op2 = convert_to_void (op2, ICV_THIRD_OF_COND, complain);
1191 }
1192 else
1193 {
1194 if (op1)
1195 new_op1 = convert_to_void (op1, ICV_CAST, complain);
1196 new_op2 = convert_to_void (op2, ICV_CAST, complain);
1197 }
1198
1199 expr = build3_loc (loc, COND_EXPR, TREE_TYPE (new_op2),
1200 TREE_OPERAND (expr, 0), new_op1, new_op2);
1201 break;
1202 }
1203
1204 case COMPOUND_EXPR:
1205 {
1206 /* The second part of a compound expr contains the value. */
1207 tree op1 = TREE_OPERAND (expr,1);
1208 tree new_op1;
1209 if (implicit != ICV_CAST && !warning_suppressed_p (expr /* What warning? */))
1210 new_op1 = convert_to_void (op1, ICV_RIGHT_OF_COMMA, complain);
1211 else
1212 new_op1 = convert_to_void (op1, ICV_CAST, complain);
1213
1214 if (new_op1 != op1)
1215 {
1216 tree t = build2_loc (loc, COMPOUND_EXPR, TREE_TYPE (new_op1),
1217 TREE_OPERAND (expr, 0), new_op1);
1218 expr = t;
1219 }
1220
1221 break;
1222 }
1223
1224 case NON_LVALUE_EXPR:
1225 case NOP_EXPR:
1226 /* These have already decayed to rvalue. */
1227 break;
1228
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
1237 language. */
1238 if (tree fn = cp_get_callee_fndecl_nofold (expr))
1239 if (DECL_CONSTRUCTOR_P (fn) || DECL_DESTRUCTOR_P (fn))
1240 return expr;
1241
1242 if (complain & tf_warning)
1243 maybe_warn_nodiscard (expr, implicit);
1244 break;
1245
1246 case INDIRECT_REF:
1247 {
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));
1252
1253 /* Can't load the value if we don't know the type. */
1254 if (is_volatile && !is_complete)
1255 {
1256 if (complain & tf_warning)
1257 switch (implicit)
1258 {
1259 case ICV_CAST:
1260 warning_at (loc, 0, "conversion to void will not access "
1261 "object of incomplete type %qT", type);
1262 break;
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);
1267 break;
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);
1272 break;
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);
1277 break;
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);
1282 break;
1283 case ICV_STATEMENT:
1284 warning_at (loc, 0, "indirection will not access object of "
1285 "incomplete type %qT in statement", type);
1286 break;
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);
1291 break;
1292 default:
1293 gcc_unreachable ();
1294 }
1295 }
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)
1299 {
1300 if (complain & tf_warning)
1301 switch (implicit)
1302 {
1303 case ICV_CAST:
1304 warning_at (loc, 0, "conversion to void will not access "
1305 "object of type %qT", type);
1306 break;
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);
1311 break;
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);
1316 break;
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);
1321 break;
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 "
1325 "operator", type);
1326 break;
1327 case ICV_STATEMENT:
1328 warning_at (loc, 0, "implicit dereference will not access "
1329 "object of type %qT in statement", type);
1330 break;
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",
1334 type);
1335 break;
1336 default:
1337 gcc_unreachable ();
1338 }
1339 }
1340 else if (is_volatile && TREE_ADDRESSABLE (type))
1341 {
1342 if (complain & tf_warning)
1343 switch (implicit)
1344 {
1345 case ICV_CAST:
1346 warning_at (loc, 0, "conversion to void will not access "
1347 "object of non-trivially-copyable type %qT",
1348 type);
1349 break;
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);
1354 break;
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);
1359 break;
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);
1364 break;
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);
1369 break;
1370 case ICV_STATEMENT:
1371 warning_at (loc, 0, "indirection will not access object of "
1372 "non-trivially-copyable type %qT in statement",
1373 type);
1374 break;
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);
1379 break;
1380 default:
1381 gcc_unreachable ();
1382 }
1383 }
1384 if (is_reference || !is_volatile || !is_complete || TREE_ADDRESSABLE (type))
1385 {
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.cc.)
1390 - automatic dereferencing of references, since the user cannot
1391 control it. (See also warn_if_unused_value() in c-common.cc.) */
1392 if (warn_unused_value
1393 && implicit != ICV_CAST
1394 && (complain & tf_warning)
1395 && !warning_suppressed_p (expr, OPT_Wunused_value)
1396 && !is_reference)
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);
1402 }
1403
1404 break;
1405 }
1406
1407 case VAR_DECL:
1408 {
1409 /* External variables might be incomplete. */
1410 tree type = TREE_TYPE (expr);
1411 int is_complete = COMPLETE_TYPE_P (complete_type (type));
1412
1413 if (TYPE_VOLATILE (type) && !is_complete && (complain & tf_warning))
1414 switch (implicit)
1415 {
1416 case ICV_CAST:
1417 warning_at (loc, 0, "conversion to void will not access "
1418 "object %qE of incomplete type %qT", expr, type);
1419 break;
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);
1424 break;
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);
1429 break;
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",
1433 expr, type);
1434 break;
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",
1438 expr, type);
1439 break;
1440 case ICV_STATEMENT:
1441 warning_at (loc, 0, "variable %qE of incomplete type %qT will "
1442 "not be accessed in statement", expr, type);
1443 break;
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",
1447 expr, type);
1448 break;
1449 default:
1450 gcc_unreachable ();
1451 }
1452
1453 break;
1454 }
1455
1456 case TARGET_EXPR:
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)))
1464 {
1465 tree init = TARGET_EXPR_INITIAL (expr);
1466 if (TREE_CODE (init) == AGGR_INIT_EXPR
1467 && !AGGR_INIT_VIA_CTOR_P (init))
1468 {
1469 tree fn = AGGR_INIT_EXPR_FN (init);
1470 expr = build_call_array_loc (input_location,
1471 TREE_TYPE (TREE_TYPE
1472 (TREE_TYPE (fn))),
1473 fn,
1474 aggr_init_expr_nargs (init),
1475 AGGR_INIT_EXPR_ARGP (init));
1476 }
1477 }
1478 if (complain & tf_warning)
1479 maybe_warn_nodiscard (expr, implicit);
1480 break;
1481
1482 default:;
1483 }
1484 expr = resolve_nondeduced_context (expr, complain);
1485 if (!mark_single_function (expr, complain))
1486 return error_mark_node;
1487
1488 {
1489 tree probe = expr;
1490
1491 if (TREE_CODE (probe) == ADDR_EXPR)
1492 probe = TREE_OPERAND (expr, 0);
1493 if (type_unknown_p (probe))
1494 {
1495 /* [over.over] enumerates the places where we can take the address
1496 of an overloaded function, and this is not one of them. */
1497 if (complain & tf_error)
1498 switch (implicit)
1499 {
1500 case ICV_CAST:
1501 error_at (loc, "conversion to void "
1502 "cannot resolve address of overloaded function");
1503 break;
1504 case ICV_SECOND_OF_COND:
1505 error_at (loc, "second operand of conditional expression "
1506 "cannot resolve address of overloaded function");
1507 break;
1508 case ICV_THIRD_OF_COND:
1509 error_at (loc, "third operand of conditional expression "
1510 "cannot resolve address of overloaded function");
1511 break;
1512 case ICV_RIGHT_OF_COMMA:
1513 error_at (loc, "right operand of comma operator "
1514 "cannot resolve address of overloaded function");
1515 break;
1516 case ICV_LEFT_OF_COMMA:
1517 error_at (loc, "left operand of comma operator "
1518 "cannot resolve address of overloaded function");
1519 break;
1520 case ICV_STATEMENT:
1521 error_at (loc, "statement "
1522 "cannot resolve address of overloaded function");
1523 break;
1524 case ICV_THIRD_IN_FOR:
1525 error_at (loc, "for increment expression "
1526 "cannot resolve address of overloaded function");
1527 break;
1528 }
1529 else
1530 return error_mark_node;
1531 expr = void_node;
1532 }
1533 else if (implicit != ICV_CAST && probe == expr && is_overloaded_fn (probe))
1534 {
1535 /* Only warn when there is no &. */
1536 if (complain & tf_warning)
1537 switch (implicit)
1538 {
1539 case ICV_SECOND_OF_COND:
1540 warning_at (loc, OPT_Waddress,
1541 "second operand of conditional expression "
1542 "is a reference, not call, to function %qE", expr);
1543 break;
1544 case ICV_THIRD_OF_COND:
1545 warning_at (loc, OPT_Waddress,
1546 "third operand of conditional expression "
1547 "is a reference, not call, to function %qE", expr);
1548 break;
1549 case ICV_RIGHT_OF_COMMA:
1550 warning_at (loc, OPT_Waddress,
1551 "right operand of comma operator "
1552 "is a reference, not call, to function %qE", expr);
1553 break;
1554 case ICV_LEFT_OF_COMMA:
1555 warning_at (loc, OPT_Waddress,
1556 "left operand of comma operator "
1557 "is a reference, not call, to function %qE", expr);
1558 break;
1559 case ICV_STATEMENT:
1560 warning_at (loc, OPT_Waddress,
1561 "statement is a reference, not call, to function %qE",
1562 expr);
1563 break;
1564 case ICV_THIRD_IN_FOR:
1565 warning_at (loc, OPT_Waddress,
1566 "for increment expression "
1567 "is a reference, not call, to function %qE", expr);
1568 break;
1569 default:
1570 gcc_unreachable ();
1571 }
1572
1573 if (TREE_CODE (expr) == COMPONENT_REF)
1574 expr = TREE_OPERAND (expr, 0);
1575 }
1576 }
1577
1578 if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
1579 {
1580 if (implicit != ICV_CAST
1581 && warn_unused_value
1582 && !warning_suppressed_p (expr, OPT_Wunused_value)
1583 && !processing_template_decl
1584 && !cp_unevaluated_operand
1585 && (complain & tf_warning))
1586 {
1587 /* The middle end does not warn about expressions that have
1588 been explicitly cast to void, so we must do so here. */
1589 if (!TREE_SIDE_EFFECTS (expr))
1590 {
1591 switch (implicit)
1592 {
1593 case ICV_SECOND_OF_COND:
1594 warning_at (loc, OPT_Wunused_value,
1595 "second operand of conditional expression "
1596 "has no effect");
1597 break;
1598 case ICV_THIRD_OF_COND:
1599 warning_at (loc, OPT_Wunused_value,
1600 "third operand of conditional expression "
1601 "has no effect");
1602 break;
1603 case ICV_RIGHT_OF_COMMA:
1604 warning_at (loc, OPT_Wunused_value,
1605 "right operand of comma operator has no effect");
1606 break;
1607 case ICV_LEFT_OF_COMMA:
1608 warning_at (loc, OPT_Wunused_value,
1609 "left operand of comma operator has no effect");
1610 break;
1611 case ICV_STATEMENT:
1612 warning_at (loc, OPT_Wunused_value,
1613 "statement has no effect");
1614 break;
1615 case ICV_THIRD_IN_FOR:
1616 warning_at (loc, OPT_Wunused_value,
1617 "for increment expression has no effect");
1618 break;
1619 default:
1620 gcc_unreachable ();
1621 }
1622 }
1623 else
1624 {
1625 tree e = expr;
1626 /* We might like to warn about (say) "(int) f()", as the
1627 cast has no effect, but the compiler itself will
1628 generate implicit conversions under some
1629 circumstances. (For example a block copy will be
1630 turned into a call to "__builtin_memcpy", with a
1631 conversion of the return value to an appropriate
1632 type.) So, to avoid false positives, we strip
1633 conversions. Do not use STRIP_NOPs because it will
1634 not strip conversions to "void", as that is not a
1635 mode-preserving conversion. */
1636 while (TREE_CODE (e) == NOP_EXPR)
1637 e = TREE_OPERAND (e, 0);
1638
1639 enum tree_code code = TREE_CODE (e);
1640 enum tree_code_class tclass = TREE_CODE_CLASS (code);
1641 if (tclass == tcc_comparison
1642 || tclass == tcc_unary
1643 || tclass == tcc_binary
1644 || code == VEC_PERM_EXPR
1645 || code == VEC_COND_EXPR)
1646 warn_if_unused_value (e, loc);
1647 }
1648 }
1649 expr = build1 (CONVERT_EXPR, void_type_node, expr);
1650 }
1651 if (! TREE_SIDE_EFFECTS (expr))
1652 expr = void_node;
1653 return expr;
1654 }
1655
1656 /* Create an expression whose value is that of EXPR,
1657 converted to type TYPE. The TREE_TYPE of the value
1658 is always TYPE. This function implements all reasonable
1659 conversions; callers should filter out those that are
1660 not permitted by the language being compiled.
1661
1662 Most of this routine is from build_reinterpret_cast.
1663
1664 The back end cannot call cp_convert (what was convert) because
1665 conversions to/from basetypes may involve memory references
1666 (vbases) and adding or subtracting small values (multiple
1667 inheritance), but it calls convert from the constant folding code
1668 on subtrees of already built trees after it has ripped them apart.
1669
1670 Also, if we ever support range variables, we'll probably also have to
1671 do a little bit more work. */
1672
1673 tree
convert(tree type,tree expr)1674 convert (tree type, tree expr)
1675 {
1676 tree intype;
1677
1678 if (type == error_mark_node || expr == error_mark_node)
1679 return error_mark_node;
1680
1681 intype = TREE_TYPE (expr);
1682
1683 if (INDIRECT_TYPE_P (type) && INDIRECT_TYPE_P (intype))
1684 return build_nop (type, expr);
1685
1686 return ocp_convert (type, expr, CONV_BACKEND_CONVERT,
1687 LOOKUP_NORMAL|LOOKUP_NO_CONVERSION,
1688 tf_warning_or_error);
1689 }
1690
1691 /* Like convert, but in a static initializer (called from
1692 convert_and_check). */
1693
1694 tree
convert_init(tree type,tree expr)1695 convert_init (tree type, tree expr)
1696 {
1697 return convert (type, expr);
1698 }
1699
1700 /* Like cp_convert, except permit conversions to take place which
1701 are not normally allowed due to access restrictions
1702 (such as conversion from sub-type to private super-type). */
1703
1704 tree
convert_force(tree type,tree expr,int convtype,tsubst_flags_t complain)1705 convert_force (tree type, tree expr, int convtype, tsubst_flags_t complain)
1706 {
1707 tree e = expr;
1708 enum tree_code code = TREE_CODE (type);
1709
1710 if (code == REFERENCE_TYPE)
1711 return convert_to_reference (type, e, CONV_C_CAST, 0,
1712 NULL_TREE, complain);
1713
1714 if (code == POINTER_TYPE)
1715 return convert_to_pointer_force (type, e, complain);
1716
1717 /* From typeck.cc convert_for_assignment */
1718 if (((TYPE_PTR_P (TREE_TYPE (e)) && TREE_CODE (e) == ADDR_EXPR
1719 && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE)
1720 || integer_zerop (e)
1721 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e)))
1722 && TYPE_PTRMEMFUNC_P (type))
1723 /* compatible pointer to member functions. */
1724 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1,
1725 /*c_cast_p=*/1, complain);
1726
1727 return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL, complain);
1728 }
1729
1730 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1731 exists, return the attempted conversion. This may
1732 return ERROR_MARK_NODE if the conversion is not
1733 allowed (references private members, etc).
1734 If no conversion exists, NULL_TREE is returned.
1735
1736 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1737 object parameter, or by the second standard conversion sequence if
1738 that doesn't do it. This will probably wait for an overloading rewrite.
1739 (jason 8/9/95) */
1740
1741 static tree
build_type_conversion(tree xtype,tree expr)1742 build_type_conversion (tree xtype, tree expr)
1743 {
1744 /* C++: check to see if we can convert this aggregate type
1745 into the required type. */
1746 return build_user_type_conversion (xtype, expr, LOOKUP_NORMAL,
1747 tf_warning_or_error);
1748 }
1749
1750 /* Convert the given EXPR to one of a group of types suitable for use in an
1751 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1752 which indicates which types are suitable. If COMPLAIN is true, complain
1753 about ambiguity; otherwise, the caller will deal with it. */
1754
1755 tree
build_expr_type_conversion(int desires,tree expr,bool complain)1756 build_expr_type_conversion (int desires, tree expr, bool complain)
1757 {
1758 tree basetype = TREE_TYPE (expr);
1759 tree conv = NULL_TREE;
1760 tree winner = NULL_TREE;
1761
1762 if (null_node_p (expr)
1763 && (desires & WANT_INT)
1764 && !(desires & WANT_NULL))
1765 {
1766 location_t loc =
1767 expansion_point_location_if_in_system_header (input_location);
1768
1769 warning_at (loc, OPT_Wconversion_null,
1770 "converting NULL to non-pointer type");
1771 }
1772
1773 if (basetype == error_mark_node)
1774 return error_mark_node;
1775
1776 if (! MAYBE_CLASS_TYPE_P (basetype))
1777 switch (TREE_CODE (basetype))
1778 {
1779 case INTEGER_TYPE:
1780 if ((desires & WANT_NULL) && null_ptr_cst_p (expr))
1781 return expr;
1782 /* fall through. */
1783
1784 case BOOLEAN_TYPE:
1785 return (desires & WANT_INT) ? expr : NULL_TREE;
1786 case ENUMERAL_TYPE:
1787 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1788 case REAL_TYPE:
1789 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1790 case POINTER_TYPE:
1791 return (desires & WANT_POINTER) ? expr : NULL_TREE;
1792
1793 case FUNCTION_TYPE:
1794 case ARRAY_TYPE:
1795 return (desires & WANT_POINTER) ? decay_conversion (expr,
1796 tf_warning_or_error)
1797 : NULL_TREE;
1798
1799 case VECTOR_TYPE:
1800 if (!gnu_vector_type_p (basetype))
1801 return NULL_TREE;
1802 /* FALLTHROUGH */
1803 case COMPLEX_TYPE:
1804 if ((desires & WANT_VECTOR_OR_COMPLEX) == 0)
1805 return NULL_TREE;
1806 switch (TREE_CODE (TREE_TYPE (basetype)))
1807 {
1808 case INTEGER_TYPE:
1809 case BOOLEAN_TYPE:
1810 return (desires & WANT_INT) ? expr : NULL_TREE;
1811 case ENUMERAL_TYPE:
1812 return (desires & WANT_ENUM) ? expr : NULL_TREE;
1813 case REAL_TYPE:
1814 return (desires & WANT_FLOAT) ? expr : NULL_TREE;
1815 default:
1816 return NULL_TREE;
1817 }
1818
1819 default:
1820 return NULL_TREE;
1821 }
1822
1823 /* The code for conversions from class type is currently only used for
1824 delete expressions. Other expressions are handled by build_new_op. */
1825 if (!complete_type_or_maybe_complain (basetype, expr, complain))
1826 return error_mark_node;
1827 if (!TYPE_HAS_CONVERSION (basetype))
1828 return NULL_TREE;
1829
1830 for (conv = lookup_conversions (basetype); conv; conv = TREE_CHAIN (conv))
1831 {
1832 int win = 0;
1833 tree candidate;
1834 tree cand = TREE_VALUE (conv);
1835 cand = OVL_FIRST (cand);
1836
1837 if (winner && winner == cand)
1838 continue;
1839
1840 if (DECL_NONCONVERTING_P (cand))
1841 continue;
1842
1843 candidate = non_reference (TREE_TYPE (TREE_TYPE (cand)));
1844
1845 switch (TREE_CODE (candidate))
1846 {
1847 case BOOLEAN_TYPE:
1848 case INTEGER_TYPE:
1849 win = (desires & WANT_INT); break;
1850 case ENUMERAL_TYPE:
1851 win = (desires & WANT_ENUM); break;
1852 case REAL_TYPE:
1853 win = (desires & WANT_FLOAT); break;
1854 case POINTER_TYPE:
1855 win = (desires & WANT_POINTER); break;
1856
1857 case COMPLEX_TYPE:
1858 case VECTOR_TYPE:
1859 if ((desires & WANT_VECTOR_OR_COMPLEX) == 0)
1860 break;
1861 switch (TREE_CODE (TREE_TYPE (candidate)))
1862 {
1863 case BOOLEAN_TYPE:
1864 case INTEGER_TYPE:
1865 win = (desires & WANT_INT); break;
1866 case ENUMERAL_TYPE:
1867 win = (desires & WANT_ENUM); break;
1868 case REAL_TYPE:
1869 win = (desires & WANT_FLOAT); break;
1870 default:
1871 break;
1872 }
1873 break;
1874
1875 default:
1876 /* A wildcard could be instantiated to match any desired
1877 type, but we can't deduce the template argument. */
1878 if (WILDCARD_TYPE_P (candidate))
1879 win = true;
1880 break;
1881 }
1882
1883 if (win)
1884 {
1885 if (TREE_CODE (cand) == TEMPLATE_DECL)
1886 {
1887 if (complain)
1888 error ("default type conversion cannot deduce template"
1889 " argument for %qD", cand);
1890 return error_mark_node;
1891 }
1892
1893 if (winner)
1894 {
1895 tree winner_type
1896 = non_reference (TREE_TYPE (TREE_TYPE (winner)));
1897
1898 if (!same_type_ignoring_top_level_qualifiers_p (winner_type,
1899 candidate))
1900 {
1901 if (complain)
1902 {
1903 error ("ambiguous default type conversion from %qT",
1904 basetype);
1905 inform (input_location,
1906 " candidate conversions include %qD and %qD",
1907 winner, cand);
1908 }
1909 return error_mark_node;
1910 }
1911 }
1912
1913 winner = cand;
1914 }
1915 }
1916
1917 if (winner)
1918 {
1919 tree type = non_reference (TREE_TYPE (TREE_TYPE (winner)));
1920 return build_user_type_conversion (type, expr, LOOKUP_NORMAL,
1921 tf_warning_or_error);
1922 }
1923
1924 return NULL_TREE;
1925 }
1926
1927 /* Implements integral promotion (4.1) and float->double promotion. */
1928
1929 tree
type_promotes_to(tree type)1930 type_promotes_to (tree type)
1931 {
1932 tree promoted_type;
1933
1934 if (type == error_mark_node)
1935 return error_mark_node;
1936
1937 type = TYPE_MAIN_VARIANT (type);
1938
1939 /* Check for promotions of target-defined types first. */
1940 promoted_type = targetm.promoted_type (type);
1941 if (promoted_type)
1942 return promoted_type;
1943
1944 /* bool always promotes to int (not unsigned), even if it's the same
1945 size. */
1946 if (TREE_CODE (type) == BOOLEAN_TYPE)
1947 type = integer_type_node;
1948
1949 /* Normally convert enums to int, but convert wide enums to something
1950 wider. Scoped enums don't promote, but pretend they do for backward
1951 ABI bug compatibility wrt varargs. */
1952 else if (TREE_CODE (type) == ENUMERAL_TYPE
1953 || type == char8_type_node
1954 || type == char16_type_node
1955 || type == char32_type_node
1956 || type == wchar_type_node)
1957 {
1958 tree prom = type;
1959
1960 if (TREE_CODE (type) == ENUMERAL_TYPE)
1961 {
1962 prom = ENUM_UNDERLYING_TYPE (prom);
1963 if (!ENUM_IS_SCOPED (type)
1964 && ENUM_FIXED_UNDERLYING_TYPE_P (type))
1965 {
1966 /* ISO C++17, 7.6/4. A prvalue of an unscoped enumeration type
1967 whose underlying type is fixed (10.2) can be converted to a
1968 prvalue of its underlying type. Moreover, if integral promotion
1969 can be applied to its underlying type, a prvalue of an unscoped
1970 enumeration type whose underlying type is fixed can also be
1971 converted to a prvalue of the promoted underlying type. */
1972 return type_promotes_to (prom);
1973 }
1974 }
1975
1976 int precision = MAX (TYPE_PRECISION (type),
1977 TYPE_PRECISION (integer_type_node));
1978 tree totype = c_common_type_for_size (precision, 0);
1979 if (TYPE_UNSIGNED (prom)
1980 && ! int_fits_type_p (TYPE_MAX_VALUE (prom), totype))
1981 prom = c_common_type_for_size (precision, 1);
1982 else
1983 prom = totype;
1984 if (SCOPED_ENUM_P (type))
1985 {
1986 if (abi_version_crosses (6)
1987 && TYPE_MODE (prom) != TYPE_MODE (type))
1988 warning (OPT_Wabi, "scoped enum %qT passed through %<...%> as "
1989 "%qT before %<-fabi-version=6%>, %qT after",
1990 type, prom, ENUM_UNDERLYING_TYPE (type));
1991 if (!abi_version_at_least (6))
1992 type = prom;
1993 }
1994 else
1995 type = prom;
1996 }
1997 else if (c_promoting_integer_type_p (type))
1998 {
1999 /* Retain unsignedness if really not getting bigger. */
2000 if (TYPE_UNSIGNED (type)
2001 && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node))
2002 type = unsigned_type_node;
2003 else
2004 type = integer_type_node;
2005 }
2006 else if (type == float_type_node)
2007 type = double_type_node;
2008
2009 return type;
2010 }
2011
2012 /* The routines below this point are carefully written to conform to
2013 the standard. They use the same terminology, and follow the rules
2014 closely. Although they are used only in pt.cc at the moment, they
2015 should presumably be used everywhere in the future. */
2016
2017 /* True iff EXPR can be converted to TYPE via a qualification conversion.
2018 Callers should check for identical types before calling this function. */
2019
2020 bool
can_convert_qual(tree type,tree expr)2021 can_convert_qual (tree type, tree expr)
2022 {
2023 tree expr_type = TREE_TYPE (expr);
2024 gcc_assert (!same_type_p (type, expr_type));
2025
2026 /* A function pointer conversion also counts as a Qualification Adjustment
2027 under [over.ics.scs]. */
2028 if (fnptr_conv_p (type, expr_type))
2029 return true;
2030
2031 if (TYPE_PTR_P (type) && TYPE_PTR_P (expr_type))
2032 return comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (expr_type));
2033 else if (TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (expr_type))
2034 return (same_type_p (TYPE_PTRMEM_CLASS_TYPE (type),
2035 TYPE_PTRMEM_CLASS_TYPE (expr_type))
2036 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type),
2037 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type)));
2038 else
2039 return false;
2040 }
2041
2042 /* Attempt to perform qualification conversions on EXPR to convert it
2043 to TYPE. Return the resulting expression, or error_mark_node if
2044 the conversion was impossible. Since this is only used by
2045 convert_nontype_argument, we fold the conversion. */
2046
2047 tree
perform_qualification_conversions(tree type,tree expr)2048 perform_qualification_conversions (tree type, tree expr)
2049 {
2050 tree expr_type;
2051
2052 expr_type = TREE_TYPE (expr);
2053
2054 if (same_type_p (type, expr_type))
2055 return expr;
2056 else if (can_convert_qual (type, expr))
2057 return cp_fold_convert (type, expr);
2058 else
2059 return error_mark_node;
2060 }
2061
2062 /* True iff T is a transaction-safe function type. */
2063
2064 bool
tx_safe_fn_type_p(tree t)2065 tx_safe_fn_type_p (tree t)
2066 {
2067 if (!FUNC_OR_METHOD_TYPE_P (t))
2068 return false;
2069 return !!lookup_attribute ("transaction_safe", TYPE_ATTRIBUTES (t));
2070 }
2071
2072 /* Return the transaction-unsafe variant of transaction-safe function type
2073 T. */
2074
2075 tree
tx_unsafe_fn_variant(tree t)2076 tx_unsafe_fn_variant (tree t)
2077 {
2078 gcc_assert (tx_safe_fn_type_p (t));
2079 tree attrs = remove_attribute ("transaction_safe",
2080 TYPE_ATTRIBUTES (t));
2081 return cp_build_type_attribute_variant (t, attrs);
2082 }
2083
2084 /* Return true iff FROM can convert to TO by a transaction-safety
2085 conversion. */
2086
2087 static bool
can_convert_tx_safety(tree to,tree from)2088 can_convert_tx_safety (tree to, tree from)
2089 {
2090 return (flag_tm && tx_safe_fn_type_p (from)
2091 && same_type_p (to, tx_unsafe_fn_variant (from)));
2092 }
2093
2094 /* Return true iff FROM can convert to TO by dropping noexcept.
2095 This is just a subroutine of fnptr_conv_p. */
2096
2097 static bool
noexcept_conv_p(tree to,tree from)2098 noexcept_conv_p (tree to, tree from)
2099 {
2100 if (!flag_noexcept_type)
2101 return false;
2102
2103 if (TREE_CODE (to) != TREE_CODE (from))
2104 return false;
2105 if (!FUNC_OR_METHOD_TYPE_P (from))
2106 return false;
2107 if (!type_throw_all_p (to)
2108 || type_throw_all_p (from))
2109 return false;
2110 tree v = build_exception_variant (from, NULL_TREE);
2111 return same_type_p (to, v);
2112 }
2113
2114 /* Return true iff FROM can convert to TO by a function pointer conversion. */
2115
2116 bool
fnptr_conv_p(tree to,tree from)2117 fnptr_conv_p (tree to, tree from)
2118 {
2119 tree t = to;
2120 tree f = from;
2121 if (TYPE_PTRMEMFUNC_P (t)
2122 && TYPE_PTRMEMFUNC_P (f))
2123 {
2124 t = TYPE_PTRMEMFUNC_FN_TYPE (t);
2125 f = TYPE_PTRMEMFUNC_FN_TYPE (f);
2126 }
2127 if (INDIRECT_TYPE_P (t)
2128 && INDIRECT_TYPE_P (f))
2129 {
2130 t = TREE_TYPE (t);
2131 f = TREE_TYPE (f);
2132 }
2133
2134 return (noexcept_conv_p (t, f)
2135 || can_convert_tx_safety (t, f));
2136 }
2137
2138 /* Return FN with any NOP_EXPRs stripped that represent function pointer
2139 conversions or conversions to the same type. */
2140
2141 tree
strip_fnptr_conv(tree fn)2142 strip_fnptr_conv (tree fn)
2143 {
2144 while (TREE_CODE (fn) == NOP_EXPR)
2145 {
2146 tree op = TREE_OPERAND (fn, 0);
2147 tree ft = TREE_TYPE (fn);
2148 tree ot = TREE_TYPE (op);
2149 if (same_type_p (ft, ot)
2150 || fnptr_conv_p (ft, ot))
2151 fn = op;
2152 else
2153 break;
2154 }
2155 return fn;
2156 }
2157