1 /* Diagnostic routines shared by all languages that are variants of C. 2 Copyright (C) 1992-2018 Free Software Foundation, Inc. 3 4 This file is part of GCC. 5 6 GCC is free software; you can redistribute it and/or modify it under 7 the terms of the GNU General Public License as published by the Free 8 Software Foundation; either version 3, or (at your option) any later 9 version. 10 11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12 WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GCC; see the file COPYING3. If not see 18 <http://www.gnu.org/licenses/>. */ 19 20 #include "config.h" 21 #include "system.h" 22 #include "coretypes.h" 23 #include "target.h" 24 #include "function.h" 25 #include "tree.h" 26 #include "c-common.h" 27 #include "memmodel.h" 28 #include "tm_p.h" 29 #include "diagnostic.h" 30 #include "intl.h" 31 #include "stringpool.h" 32 #include "attribs.h" 33 #include "asan.h" 34 #include "gcc-rich-location.h" 35 #include "gimplify.h" 36 #include "c-family/c-indentation.h" 37 #include "calls.h" 38 39 /* Print a warning if a constant expression had overflow in folding. 40 Invoke this function on every expression that the language 41 requires to be a constant expression. 42 Note the ANSI C standard says it is erroneous for a 43 constant expression to overflow. */ 44 45 void 46 constant_expression_warning (tree value) 47 { 48 if (warn_overflow && pedantic 49 && (TREE_CODE (value) == INTEGER_CST || TREE_CODE (value) == REAL_CST 50 || TREE_CODE (value) == FIXED_CST 51 || TREE_CODE (value) == VECTOR_CST 52 || TREE_CODE (value) == COMPLEX_CST) 53 && TREE_OVERFLOW (value)) 54 pedwarn (input_location, OPT_Woverflow, "overflow in constant expression"); 55 } 56 57 /* The same as above but print an unconditional error. */ 58 59 void 60 constant_expression_error (tree value) 61 { 62 if ((TREE_CODE (value) == INTEGER_CST || TREE_CODE (value) == REAL_CST 63 || TREE_CODE (value) == FIXED_CST 64 || TREE_CODE (value) == VECTOR_CST 65 || TREE_CODE (value) == COMPLEX_CST) 66 && TREE_OVERFLOW (value)) 67 error ("overflow in constant expression"); 68 } 69 70 /* Print a warning if an expression result VALUE had an overflow 71 in folding and its operands hadn't. EXPR, which may be null, is 72 the operand of the expression. 73 74 Invoke this function on every expression that 75 (1) appears in the source code, and 76 (2) is a constant expression that overflowed, and 77 (3) is not already checked by convert_and_check; 78 however, do not invoke this function on operands of explicit casts 79 or when the expression is the result of an operator and any operand 80 already overflowed. */ 81 82 void 83 overflow_warning (location_t loc, tree value, tree expr) 84 { 85 if (c_inhibit_evaluation_warnings != 0) 86 return; 87 88 const char *warnfmt = NULL; 89 90 switch (TREE_CODE (value)) 91 { 92 case INTEGER_CST: 93 warnfmt = (expr 94 ? G_("integer overflow in expression %qE of type %qT " 95 "results in %qE") 96 : G_("integer overflow in expression of type %qT " 97 "results in %qE")); 98 break; 99 100 case REAL_CST: 101 warnfmt = (expr 102 ? G_ ("floating point overflow in expression %qE " 103 "of type %qT results in %qE") 104 : G_ ("floating point overflow in expression of type %qT " 105 "results in %qE")); 106 break; 107 108 case FIXED_CST: 109 warnfmt = (expr 110 ? G_("fixed-point overflow in expression %qE of type %qT " 111 "results in %qE") 112 : G_("fixed-point overflow in expression of type %qT " 113 "results in %qE")); 114 break; 115 116 case VECTOR_CST: 117 warnfmt = (expr 118 ? G_("vector overflow in expression %qE of type %qT " 119 "results in %qE") 120 : G_("vector overflow in expression of type %qT " 121 "results in %qE")); 122 break; 123 124 case COMPLEX_CST: 125 if (TREE_CODE (TREE_REALPART (value)) == INTEGER_CST) 126 warnfmt = (expr 127 ? G_("complex integer overflow in expression %qE " 128 "of type %qT results in %qE") 129 : G_("complex integer overflow in expression of type %qT " 130 "results in %qE")); 131 else if (TREE_CODE (TREE_REALPART (value)) == REAL_CST) 132 warnfmt = (expr 133 ? G_("complex floating point overflow in expression %qE " 134 "of type %qT results in %qE") 135 : G_("complex floating point overflow in expression " 136 "of type %qT results in %qE")); 137 else 138 return; 139 break; 140 141 default: 142 return; 143 } 144 145 if (expr) 146 warning_at (loc, OPT_Woverflow, warnfmt, expr, TREE_TYPE (expr), value); 147 else 148 warning_at (loc, OPT_Woverflow, warnfmt, TREE_TYPE (value), value); 149 150 TREE_NO_WARNING (value) = 1; 151 } 152 153 /* Helper function for walk_tree. Unwrap C_MAYBE_CONST_EXPRs in an expression 154 pointed to by TP. */ 155 156 static tree 157 unwrap_c_maybe_const (tree *tp, int *walk_subtrees, void *) 158 { 159 if (TREE_CODE (*tp) == C_MAYBE_CONST_EXPR) 160 { 161 *tp = C_MAYBE_CONST_EXPR_EXPR (*tp); 162 /* C_MAYBE_CONST_EXPRs don't nest. */ 163 *walk_subtrees = false; 164 } 165 return NULL_TREE; 166 } 167 168 /* Warn about uses of logical || / && operator in a context where it 169 is likely that the bitwise equivalent was intended by the 170 programmer. We have seen an expression in which CODE is a binary 171 operator used to combine expressions OP_LEFT and OP_RIGHT, which before folding 172 had CODE_LEFT and CODE_RIGHT, into an expression of type TYPE. */ 173 174 void 175 warn_logical_operator (location_t location, enum tree_code code, tree type, 176 enum tree_code code_left, tree op_left, 177 enum tree_code ARG_UNUSED (code_right), tree op_right) 178 { 179 int or_op = (code == TRUTH_ORIF_EXPR || code == TRUTH_OR_EXPR); 180 int in0_p, in1_p, in_p; 181 tree low0, low1, low, high0, high1, high, lhs, rhs, tem; 182 bool strict_overflow_p = false; 183 184 if (!warn_logical_op) 185 return; 186 187 if (code != TRUTH_ANDIF_EXPR 188 && code != TRUTH_AND_EXPR 189 && code != TRUTH_ORIF_EXPR 190 && code != TRUTH_OR_EXPR) 191 return; 192 193 /* We don't want to warn if either operand comes from a macro 194 expansion. ??? This doesn't work with e.g. NEGATE_EXPR yet; 195 see PR61534. */ 196 if (from_macro_expansion_at (EXPR_LOCATION (op_left)) 197 || from_macro_expansion_at (EXPR_LOCATION (op_right))) 198 return; 199 200 /* Warn if &&/|| are being used in a context where it is 201 likely that the bitwise equivalent was intended by the 202 programmer. That is, an expression such as op && MASK 203 where op should not be any boolean expression, nor a 204 constant, and mask seems to be a non-boolean integer constant. */ 205 if (TREE_CODE (op_right) == CONST_DECL) 206 /* An enumerator counts as a constant. */ 207 op_right = DECL_INITIAL (op_right); 208 if (!truth_value_p (code_left) 209 && INTEGRAL_TYPE_P (TREE_TYPE (op_left)) 210 && !CONSTANT_CLASS_P (op_left) 211 && !TREE_NO_WARNING (op_left) 212 && TREE_CODE (op_right) == INTEGER_CST 213 && !integer_zerop (op_right) 214 && !integer_onep (op_right)) 215 { 216 if (or_op) 217 warning_at (location, OPT_Wlogical_op, "logical %<or%>" 218 " applied to non-boolean constant"); 219 else 220 warning_at (location, OPT_Wlogical_op, "logical %<and%>" 221 " applied to non-boolean constant"); 222 TREE_NO_WARNING (op_left) = true; 223 return; 224 } 225 226 /* We do not warn for constants because they are typical of macro 227 expansions that test for features. */ 228 if (CONSTANT_CLASS_P (fold_for_warn (op_left)) 229 || CONSTANT_CLASS_P (fold_for_warn (op_right))) 230 return; 231 232 /* This warning only makes sense with logical operands. */ 233 if (!(truth_value_p (TREE_CODE (op_left)) 234 || INTEGRAL_TYPE_P (TREE_TYPE (op_left))) 235 || !(truth_value_p (TREE_CODE (op_right)) 236 || INTEGRAL_TYPE_P (TREE_TYPE (op_right)))) 237 return; 238 239 /* The range computations only work with scalars. */ 240 if (VECTOR_TYPE_P (TREE_TYPE (op_left)) 241 || VECTOR_TYPE_P (TREE_TYPE (op_right))) 242 return; 243 244 /* We first test whether either side separately is trivially true 245 (with OR) or trivially false (with AND). If so, do not warn. 246 This is a common idiom for testing ranges of data types in 247 portable code. */ 248 op_left = unshare_expr (op_left); 249 walk_tree_without_duplicates (&op_left, unwrap_c_maybe_const, NULL); 250 lhs = make_range (op_left, &in0_p, &low0, &high0, &strict_overflow_p); 251 if (!lhs) 252 return; 253 254 /* If this is an OR operation, invert both sides; now, the result 255 should be always false to get a warning. */ 256 if (or_op) 257 in0_p = !in0_p; 258 259 tem = build_range_check (UNKNOWN_LOCATION, type, lhs, in0_p, low0, high0); 260 if (tem && integer_zerop (tem)) 261 return; 262 263 op_right = unshare_expr (op_right); 264 walk_tree_without_duplicates (&op_right, unwrap_c_maybe_const, NULL); 265 rhs = make_range (op_right, &in1_p, &low1, &high1, &strict_overflow_p); 266 if (!rhs) 267 return; 268 269 /* If this is an OR operation, invert both sides; now, the result 270 should be always false to get a warning. */ 271 if (or_op) 272 in1_p = !in1_p; 273 274 tem = build_range_check (UNKNOWN_LOCATION, type, rhs, in1_p, low1, high1); 275 if (tem && integer_zerop (tem)) 276 return; 277 278 /* If both expressions have the same operand, if we can merge the 279 ranges, ... */ 280 if (operand_equal_p (lhs, rhs, 0) 281 && merge_ranges (&in_p, &low, &high, in0_p, low0, high0, 282 in1_p, low1, high1)) 283 { 284 tem = build_range_check (UNKNOWN_LOCATION, type, lhs, in_p, low, high); 285 /* ... and if the range test is always false, then warn. */ 286 if (tem && integer_zerop (tem)) 287 { 288 if (or_op) 289 warning_at (location, OPT_Wlogical_op, 290 "logical %<or%> of collectively exhaustive tests is " 291 "always true"); 292 else 293 warning_at (location, OPT_Wlogical_op, 294 "logical %<and%> of mutually exclusive tests is " 295 "always false"); 296 } 297 /* Or warn if the operands have exactly the same range, e.g. 298 A > 0 && A > 0. */ 299 else if (tree_int_cst_equal (low0, low1) 300 && tree_int_cst_equal (high0, high1)) 301 { 302 if (or_op) 303 warning_at (location, OPT_Wlogical_op, 304 "logical %<or%> of equal expressions"); 305 else 306 warning_at (location, OPT_Wlogical_op, 307 "logical %<and%> of equal expressions"); 308 } 309 } 310 } 311 312 /* Helper function for warn_tautological_cmp. Look for ARRAY_REFs 313 with constant indices. */ 314 315 static tree 316 find_array_ref_with_const_idx_r (tree *expr_p, int *, void *) 317 { 318 tree expr = *expr_p; 319 320 if ((TREE_CODE (expr) == ARRAY_REF 321 || TREE_CODE (expr) == ARRAY_RANGE_REF) 322 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST) 323 return integer_type_node; 324 325 return NULL_TREE; 326 } 327 328 /* Subroutine of warn_tautological_cmp. Warn about bitwise comparison 329 that always evaluate to true or false. LOC is the location of the 330 ==/!= comparison specified by CODE; LHS and RHS are the usual operands 331 of this comparison. */ 332 333 static void 334 warn_tautological_bitwise_comparison (location_t loc, tree_code code, 335 tree lhs, tree rhs) 336 { 337 if (code != EQ_EXPR && code != NE_EXPR) 338 return; 339 340 /* Extract the operands from e.g. (x & 8) == 4. */ 341 tree bitop; 342 tree cst; 343 if ((TREE_CODE (lhs) == BIT_AND_EXPR 344 || TREE_CODE (lhs) == BIT_IOR_EXPR) 345 && TREE_CODE (rhs) == INTEGER_CST) 346 bitop = lhs, cst = rhs; 347 else if ((TREE_CODE (rhs) == BIT_AND_EXPR 348 || TREE_CODE (rhs) == BIT_IOR_EXPR) 349 && TREE_CODE (lhs) == INTEGER_CST) 350 bitop = rhs, cst = lhs; 351 else 352 return; 353 354 tree bitopcst; 355 if (TREE_CODE (TREE_OPERAND (bitop, 0)) == INTEGER_CST) 356 bitopcst = TREE_OPERAND (bitop, 0); 357 else if (TREE_CODE (TREE_OPERAND (bitop, 1)) == INTEGER_CST) 358 bitopcst = TREE_OPERAND (bitop, 1); 359 else 360 return; 361 362 /* Note that the two operands are from before the usual integer 363 conversions, so their types might not be the same. 364 Use the larger of the two precisions and ignore bits outside 365 of that. */ 366 int prec = MAX (TYPE_PRECISION (TREE_TYPE (cst)), 367 TYPE_PRECISION (TREE_TYPE (bitopcst))); 368 369 wide_int bitopcstw = wi::to_wide (bitopcst, prec); 370 wide_int cstw = wi::to_wide (cst, prec); 371 372 wide_int res; 373 if (TREE_CODE (bitop) == BIT_AND_EXPR) 374 res = bitopcstw & cstw; 375 else 376 res = bitopcstw | cstw; 377 378 /* For BIT_AND only warn if (CST2 & CST1) != CST1, and 379 for BIT_OR only if (CST2 | CST1) != CST1. */ 380 if (res == cstw) 381 return; 382 383 if (code == EQ_EXPR) 384 warning_at (loc, OPT_Wtautological_compare, 385 "bitwise comparison always evaluates to false"); 386 else 387 warning_at (loc, OPT_Wtautological_compare, 388 "bitwise comparison always evaluates to true"); 389 } 390 391 /* Warn if a self-comparison always evaluates to true or false. LOC 392 is the location of the comparison with code CODE, LHS and RHS are 393 operands of the comparison. */ 394 395 void 396 warn_tautological_cmp (location_t loc, enum tree_code code, tree lhs, tree rhs) 397 { 398 if (TREE_CODE_CLASS (code) != tcc_comparison) 399 return; 400 401 /* Don't warn for various macro expansions. */ 402 if (from_macro_expansion_at (loc) 403 || from_macro_expansion_at (EXPR_LOCATION (lhs)) 404 || from_macro_expansion_at (EXPR_LOCATION (rhs))) 405 return; 406 407 warn_tautological_bitwise_comparison (loc, code, lhs, rhs); 408 409 /* We do not warn for constants because they are typical of macro 410 expansions that test for features, sizeof, and similar. */ 411 if (CONSTANT_CLASS_P (fold_for_warn (lhs)) 412 || CONSTANT_CLASS_P (fold_for_warn (rhs))) 413 return; 414 415 /* Don't warn for e.g. 416 HOST_WIDE_INT n; 417 ... 418 if (n == (long) n) ... 419 */ 420 if ((CONVERT_EXPR_P (lhs) || TREE_CODE (lhs) == NON_LVALUE_EXPR) 421 || (CONVERT_EXPR_P (rhs) || TREE_CODE (rhs) == NON_LVALUE_EXPR)) 422 return; 423 424 /* Don't warn if either LHS or RHS has an IEEE floating-point type. 425 It could be a NaN, and NaN never compares equal to anything, even 426 itself. */ 427 if (FLOAT_TYPE_P (TREE_TYPE (lhs)) || FLOAT_TYPE_P (TREE_TYPE (rhs))) 428 return; 429 430 if (operand_equal_p (lhs, rhs, 0)) 431 { 432 /* Don't warn about array references with constant indices; 433 these are likely to come from a macro. */ 434 if (walk_tree_without_duplicates (&lhs, find_array_ref_with_const_idx_r, 435 NULL)) 436 return; 437 const bool always_true = (code == EQ_EXPR || code == LE_EXPR 438 || code == GE_EXPR || code == UNLE_EXPR 439 || code == UNGE_EXPR || code == UNEQ_EXPR); 440 if (always_true) 441 warning_at (loc, OPT_Wtautological_compare, 442 "self-comparison always evaluates to true"); 443 else 444 warning_at (loc, OPT_Wtautological_compare, 445 "self-comparison always evaluates to false"); 446 } 447 } 448 449 /* Return true iff EXPR only contains boolean operands, or comparisons. */ 450 451 static bool 452 expr_has_boolean_operands_p (tree expr) 453 { 454 STRIP_NOPS (expr); 455 456 if (CONVERT_EXPR_P (expr)) 457 return bool_promoted_to_int_p (expr); 458 else if (UNARY_CLASS_P (expr)) 459 return expr_has_boolean_operands_p (TREE_OPERAND (expr, 0)); 460 else if (BINARY_CLASS_P (expr)) 461 return (expr_has_boolean_operands_p (TREE_OPERAND (expr, 0)) 462 && expr_has_boolean_operands_p (TREE_OPERAND (expr, 1))); 463 else if (COMPARISON_CLASS_P (expr)) 464 return true; 465 else 466 return false; 467 } 468 469 /* Warn about logical not used on the left hand side operand of a comparison. 470 This function assumes that the LHS is inside of TRUTH_NOT_EXPR. 471 Do not warn if RHS is of a boolean type, a logical operator, or 472 a comparison. */ 473 474 void 475 warn_logical_not_parentheses (location_t location, enum tree_code code, 476 tree lhs, tree rhs) 477 { 478 if (TREE_CODE_CLASS (code) != tcc_comparison 479 || TREE_TYPE (rhs) == NULL_TREE 480 || TREE_CODE (TREE_TYPE (rhs)) == BOOLEAN_TYPE 481 || truth_value_p (TREE_CODE (rhs))) 482 return; 483 484 /* Don't warn for expression like !x == ~(bool1 | bool2). */ 485 if (expr_has_boolean_operands_p (rhs)) 486 return; 487 488 /* Don't warn for !x == 0 or !y != 0, those are equivalent to 489 !(x == 0) or !(y != 0). */ 490 if ((code == EQ_EXPR || code == NE_EXPR) 491 && integer_zerop (rhs)) 492 return; 493 494 if (warning_at (location, OPT_Wlogical_not_parentheses, 495 "logical not is only applied to the left hand side of " 496 "comparison") 497 && EXPR_HAS_LOCATION (lhs)) 498 { 499 location_t lhs_loc = EXPR_LOCATION (lhs); 500 rich_location richloc (line_table, lhs_loc); 501 richloc.add_fixit_insert_before (lhs_loc, "("); 502 richloc.add_fixit_insert_after (lhs_loc, ")"); 503 inform (&richloc, "add parentheses around left hand side " 504 "expression to silence this warning"); 505 } 506 } 507 508 /* Warn if EXP contains any computations whose results are not used. 509 Return true if a warning is printed; false otherwise. LOCUS is the 510 (potential) location of the expression. */ 511 512 bool 513 warn_if_unused_value (const_tree exp, location_t locus) 514 { 515 restart: 516 if (TREE_USED (exp) || TREE_NO_WARNING (exp)) 517 return false; 518 519 /* Don't warn about void constructs. This includes casting to void, 520 void function calls, and statement expressions with a final cast 521 to void. */ 522 if (VOID_TYPE_P (TREE_TYPE (exp))) 523 return false; 524 525 if (EXPR_HAS_LOCATION (exp)) 526 locus = EXPR_LOCATION (exp); 527 528 switch (TREE_CODE (exp)) 529 { 530 case PREINCREMENT_EXPR: 531 case POSTINCREMENT_EXPR: 532 case PREDECREMENT_EXPR: 533 case POSTDECREMENT_EXPR: 534 case MODIFY_EXPR: 535 case INIT_EXPR: 536 case TARGET_EXPR: 537 case CALL_EXPR: 538 case TRY_CATCH_EXPR: 539 case EXIT_EXPR: 540 case VA_ARG_EXPR: 541 return false; 542 543 case BIND_EXPR: 544 /* For a binding, warn if no side effect within it. */ 545 exp = BIND_EXPR_BODY (exp); 546 goto restart; 547 548 case SAVE_EXPR: 549 case NON_LVALUE_EXPR: 550 case NOP_EXPR: 551 exp = TREE_OPERAND (exp, 0); 552 goto restart; 553 554 case TRUTH_ORIF_EXPR: 555 case TRUTH_ANDIF_EXPR: 556 /* In && or ||, warn if 2nd operand has no side effect. */ 557 exp = TREE_OPERAND (exp, 1); 558 goto restart; 559 560 case COMPOUND_EXPR: 561 if (warn_if_unused_value (TREE_OPERAND (exp, 0), locus)) 562 return true; 563 /* Let people do `(foo (), 0)' without a warning. */ 564 if (TREE_CONSTANT (TREE_OPERAND (exp, 1))) 565 return false; 566 exp = TREE_OPERAND (exp, 1); 567 goto restart; 568 569 case COND_EXPR: 570 /* If this is an expression with side effects, don't warn; this 571 case commonly appears in macro expansions. */ 572 if (TREE_SIDE_EFFECTS (exp)) 573 return false; 574 goto warn; 575 576 case INDIRECT_REF: 577 /* Don't warn about automatic dereferencing of references, since 578 the user cannot control it. */ 579 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == REFERENCE_TYPE) 580 { 581 exp = TREE_OPERAND (exp, 0); 582 goto restart; 583 } 584 /* Fall through. */ 585 586 default: 587 /* Referencing a volatile value is a side effect, so don't warn. */ 588 if ((DECL_P (exp) || REFERENCE_CLASS_P (exp)) 589 && TREE_THIS_VOLATILE (exp)) 590 return false; 591 592 /* If this is an expression which has no operands, there is no value 593 to be unused. There are no such language-independent codes, 594 but front ends may define such. */ 595 if (EXPRESSION_CLASS_P (exp) && TREE_OPERAND_LENGTH (exp) == 0) 596 return false; 597 598 warn: 599 return warning_at (locus, OPT_Wunused_value, "value computed is not used"); 600 } 601 } 602 603 /* Print a warning about casts that might indicate violation of strict 604 aliasing rules if -Wstrict-aliasing is used and strict aliasing 605 mode is in effect. LOC is the location of the expression being 606 cast, EXPR might be from inside it. TYPE is the type we're casting 607 to. */ 608 609 bool 610 strict_aliasing_warning (location_t loc, tree type, tree expr) 611 { 612 if (loc == UNKNOWN_LOCATION) 613 loc = input_location; 614 615 /* Strip pointer conversion chains and get to the correct original type. */ 616 STRIP_NOPS (expr); 617 tree otype = TREE_TYPE (expr); 618 619 if (!(flag_strict_aliasing 620 && POINTER_TYPE_P (type) 621 && POINTER_TYPE_P (otype) 622 && !VOID_TYPE_P (TREE_TYPE (type))) 623 /* If the type we are casting to is a ref-all pointer 624 dereferencing it is always valid. */ 625 || TYPE_REF_CAN_ALIAS_ALL (type)) 626 return false; 627 628 if ((warn_strict_aliasing > 1) && TREE_CODE (expr) == ADDR_EXPR 629 && (DECL_P (TREE_OPERAND (expr, 0)) 630 || handled_component_p (TREE_OPERAND (expr, 0)))) 631 { 632 /* Casting the address of an object to non void pointer. Warn 633 if the cast breaks type based aliasing. */ 634 if (!COMPLETE_TYPE_P (TREE_TYPE (type)) && warn_strict_aliasing == 2) 635 { 636 warning_at (loc, OPT_Wstrict_aliasing, 637 "type-punning to incomplete type " 638 "might break strict-aliasing rules"); 639 return true; 640 } 641 else 642 { 643 /* warn_strict_aliasing >= 3. This includes the default (3). 644 Only warn if the cast is dereferenced immediately. */ 645 alias_set_type set1 646 = get_alias_set (TREE_TYPE (TREE_OPERAND (expr, 0))); 647 alias_set_type set2 = get_alias_set (TREE_TYPE (type)); 648 649 if (set2 != 0 650 && set1 != set2 651 && !alias_set_subset_of (set2, set1) 652 && !alias_sets_conflict_p (set1, set2)) 653 { 654 warning_at (loc, OPT_Wstrict_aliasing, 655 "dereferencing type-punned " 656 "pointer will break strict-aliasing rules"); 657 return true; 658 } 659 else if (warn_strict_aliasing == 2 660 && !alias_sets_must_conflict_p (set1, set2)) 661 { 662 warning_at (loc, OPT_Wstrict_aliasing, 663 "dereferencing type-punned " 664 "pointer might break strict-aliasing rules"); 665 return true; 666 } 667 } 668 } 669 else if ((warn_strict_aliasing == 1) && !VOID_TYPE_P (TREE_TYPE (otype))) 670 { 671 /* At this level, warn for any conversions, even if an address is 672 not taken in the same statement. This will likely produce many 673 false positives, but could be useful to pinpoint problems that 674 are not revealed at higher levels. */ 675 alias_set_type set1 = get_alias_set (TREE_TYPE (otype)); 676 alias_set_type set2 = get_alias_set (TREE_TYPE (type)); 677 if (!COMPLETE_TYPE_P (type) 678 || !alias_sets_must_conflict_p (set1, set2)) 679 { 680 warning_at (loc, OPT_Wstrict_aliasing, 681 "dereferencing type-punned " 682 "pointer might break strict-aliasing rules"); 683 return true; 684 } 685 } 686 687 return false; 688 } 689 690 /* Warn about memset (&a, 0, sizeof (&a)); and similar mistakes with 691 sizeof as last operand of certain builtins. */ 692 693 void 694 sizeof_pointer_memaccess_warning (location_t *sizeof_arg_loc, tree callee, 695 vec<tree, va_gc> *params, tree *sizeof_arg, 696 bool (*comp_types) (tree, tree)) 697 { 698 tree type, dest = NULL_TREE, src = NULL_TREE, tem; 699 bool strop = false, cmp = false; 700 unsigned int idx = ~0; 701 location_t loc; 702 703 if (TREE_CODE (callee) != FUNCTION_DECL 704 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL 705 || vec_safe_length (params) <= 1) 706 return; 707 708 enum built_in_function fncode = DECL_FUNCTION_CODE (callee); 709 switch (fncode) 710 { 711 case BUILT_IN_STRNCMP: 712 case BUILT_IN_STRNCASECMP: 713 cmp = true; 714 /* FALLTHRU */ 715 case BUILT_IN_STRNCPY: 716 case BUILT_IN_STRNCPY_CHK: 717 case BUILT_IN_STRNCAT: 718 case BUILT_IN_STRNCAT_CHK: 719 case BUILT_IN_STPNCPY: 720 case BUILT_IN_STPNCPY_CHK: 721 strop = true; 722 /* FALLTHRU */ 723 case BUILT_IN_MEMCPY: 724 case BUILT_IN_MEMCPY_CHK: 725 case BUILT_IN_MEMMOVE: 726 case BUILT_IN_MEMMOVE_CHK: 727 if (params->length () < 3) 728 return; 729 src = (*params)[1]; 730 dest = (*params)[0]; 731 idx = 2; 732 break; 733 case BUILT_IN_BCOPY: 734 if (params->length () < 3) 735 return; 736 src = (*params)[0]; 737 dest = (*params)[1]; 738 idx = 2; 739 break; 740 case BUILT_IN_MEMCMP: 741 case BUILT_IN_BCMP: 742 if (params->length () < 3) 743 return; 744 src = (*params)[1]; 745 dest = (*params)[0]; 746 idx = 2; 747 cmp = true; 748 break; 749 case BUILT_IN_MEMSET: 750 case BUILT_IN_MEMSET_CHK: 751 if (params->length () < 3) 752 return; 753 dest = (*params)[0]; 754 idx = 2; 755 break; 756 case BUILT_IN_BZERO: 757 dest = (*params)[0]; 758 idx = 1; 759 break; 760 case BUILT_IN_STRNDUP: 761 src = (*params)[0]; 762 strop = true; 763 idx = 1; 764 break; 765 case BUILT_IN_MEMCHR: 766 if (params->length () < 3) 767 return; 768 src = (*params)[0]; 769 idx = 2; 770 break; 771 case BUILT_IN_SNPRINTF: 772 case BUILT_IN_SNPRINTF_CHK: 773 case BUILT_IN_VSNPRINTF: 774 case BUILT_IN_VSNPRINTF_CHK: 775 dest = (*params)[0]; 776 idx = 1; 777 strop = true; 778 break; 779 default: 780 break; 781 } 782 783 if (idx >= 3) 784 return; 785 786 if (sizeof_arg[idx] == NULL || sizeof_arg[idx] == error_mark_node) 787 return; 788 789 type = TYPE_P (sizeof_arg[idx]) 790 ? sizeof_arg[idx] : TREE_TYPE (sizeof_arg[idx]); 791 792 if (!POINTER_TYPE_P (type)) 793 { 794 /* The argument type may be an array. Diagnose bounded string 795 copy functions that specify the bound in terms of the source 796 argument rather than the destination. */ 797 if (strop && !cmp && fncode != BUILT_IN_STRNDUP && src) 798 { 799 tem = tree_strip_nop_conversions (src); 800 if (TREE_CODE (tem) == ADDR_EXPR) 801 tem = TREE_OPERAND (tem, 0); 802 803 /* Avoid diagnosing sizeof SRC when SRC is declared with 804 attribute nonstring. */ 805 tree dummy; 806 if (get_attr_nonstring_decl (tem, &dummy)) 807 return; 808 809 if (operand_equal_p (tem, sizeof_arg[idx], OEP_ADDRESS_OF)) 810 warning_at (sizeof_arg_loc[idx], OPT_Wsizeof_pointer_memaccess, 811 "argument to %<sizeof%> in %qD call is the same " 812 "expression as the source; did you mean to use " 813 "the size of the destination?", 814 callee); 815 } 816 817 return; 818 } 819 820 if (dest 821 && (tem = tree_strip_nop_conversions (dest)) 822 && POINTER_TYPE_P (TREE_TYPE (tem)) 823 && comp_types (TREE_TYPE (TREE_TYPE (tem)), type)) 824 return; 825 826 if (src 827 && (tem = tree_strip_nop_conversions (src)) 828 && POINTER_TYPE_P (TREE_TYPE (tem)) 829 && comp_types (TREE_TYPE (TREE_TYPE (tem)), type)) 830 return; 831 832 loc = sizeof_arg_loc[idx]; 833 834 if (dest && !cmp) 835 { 836 if (!TYPE_P (sizeof_arg[idx]) 837 && operand_equal_p (dest, sizeof_arg[idx], 0) 838 && comp_types (TREE_TYPE (dest), type)) 839 { 840 if (TREE_CODE (sizeof_arg[idx]) == ADDR_EXPR && !strop) 841 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 842 "argument to %<sizeof%> in %qD call is the same " 843 "expression as the destination; did you mean to " 844 "remove the addressof?", callee); 845 else if ((TYPE_PRECISION (TREE_TYPE (type)) 846 == TYPE_PRECISION (char_type_node)) 847 || strop) 848 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 849 "argument to %<sizeof%> in %qD call is the same " 850 "expression as the destination; did you mean to " 851 "provide an explicit length?", callee); 852 else 853 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 854 "argument to %<sizeof%> in %qD call is the same " 855 "expression as the destination; did you mean to " 856 "dereference it?", callee); 857 return; 858 } 859 860 if (POINTER_TYPE_P (TREE_TYPE (dest)) 861 && !strop 862 && comp_types (TREE_TYPE (dest), type) 863 && !VOID_TYPE_P (TREE_TYPE (type))) 864 { 865 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 866 "argument to %<sizeof%> in %qD call is the same " 867 "pointer type %qT as the destination; expected %qT " 868 "or an explicit length", callee, TREE_TYPE (dest), 869 TREE_TYPE (TREE_TYPE (dest))); 870 return; 871 } 872 } 873 874 if (src && !cmp) 875 { 876 if (!TYPE_P (sizeof_arg[idx]) 877 && operand_equal_p (src, sizeof_arg[idx], 0) 878 && comp_types (TREE_TYPE (src), type)) 879 { 880 if (TREE_CODE (sizeof_arg[idx]) == ADDR_EXPR && !strop) 881 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 882 "argument to %<sizeof%> in %qD call is the same " 883 "expression as the source; did you mean to " 884 "remove the addressof?", callee); 885 else if ((TYPE_PRECISION (TREE_TYPE (type)) 886 == TYPE_PRECISION (char_type_node)) 887 || strop) 888 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 889 "argument to %<sizeof%> in %qD call is the same " 890 "expression as the source; did you mean to " 891 "provide an explicit length?", callee); 892 else 893 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 894 "argument to %<sizeof%> in %qD call is the same " 895 "expression as the source; did you mean to " 896 "dereference it?", callee); 897 return; 898 } 899 900 if (POINTER_TYPE_P (TREE_TYPE (src)) 901 && !strop 902 && comp_types (TREE_TYPE (src), type) 903 && !VOID_TYPE_P (TREE_TYPE (type))) 904 { 905 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 906 "argument to %<sizeof%> in %qD call is the same " 907 "pointer type %qT as the source; expected %qT " 908 "or an explicit length", callee, TREE_TYPE (src), 909 TREE_TYPE (TREE_TYPE (src))); 910 return; 911 } 912 } 913 914 if (dest) 915 { 916 if (!TYPE_P (sizeof_arg[idx]) 917 && operand_equal_p (dest, sizeof_arg[idx], 0) 918 && comp_types (TREE_TYPE (dest), type)) 919 { 920 if (TREE_CODE (sizeof_arg[idx]) == ADDR_EXPR && !strop) 921 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 922 "argument to %<sizeof%> in %qD call is the same " 923 "expression as the first source; did you mean to " 924 "remove the addressof?", callee); 925 else if ((TYPE_PRECISION (TREE_TYPE (type)) 926 == TYPE_PRECISION (char_type_node)) 927 || strop) 928 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 929 "argument to %<sizeof%> in %qD call is the same " 930 "expression as the first source; did you mean to " 931 "provide an explicit length?", callee); 932 else 933 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 934 "argument to %<sizeof%> in %qD call is the same " 935 "expression as the first source; did you mean to " 936 "dereference it?", callee); 937 return; 938 } 939 940 if (POINTER_TYPE_P (TREE_TYPE (dest)) 941 && !strop 942 && comp_types (TREE_TYPE (dest), type) 943 && !VOID_TYPE_P (TREE_TYPE (type))) 944 { 945 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 946 "argument to %<sizeof%> in %qD call is the same " 947 "pointer type %qT as the first source; expected %qT " 948 "or an explicit length", callee, TREE_TYPE (dest), 949 TREE_TYPE (TREE_TYPE (dest))); 950 return; 951 } 952 } 953 954 if (src) 955 { 956 if (!TYPE_P (sizeof_arg[idx]) 957 && operand_equal_p (src, sizeof_arg[idx], 0) 958 && comp_types (TREE_TYPE (src), type)) 959 { 960 if (TREE_CODE (sizeof_arg[idx]) == ADDR_EXPR && !strop) 961 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 962 "argument to %<sizeof%> in %qD call is the same " 963 "expression as the second source; did you mean to " 964 "remove the addressof?", callee); 965 else if ((TYPE_PRECISION (TREE_TYPE (type)) 966 == TYPE_PRECISION (char_type_node)) 967 || strop) 968 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 969 "argument to %<sizeof%> in %qD call is the same " 970 "expression as the second source; did you mean to " 971 "provide an explicit length?", callee); 972 else 973 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 974 "argument to %<sizeof%> in %qD call is the same " 975 "expression as the second source; did you mean to " 976 "dereference it?", callee); 977 return; 978 } 979 980 if (POINTER_TYPE_P (TREE_TYPE (src)) 981 && !strop 982 && comp_types (TREE_TYPE (src), type) 983 && !VOID_TYPE_P (TREE_TYPE (type))) 984 { 985 warning_at (loc, OPT_Wsizeof_pointer_memaccess, 986 "argument to %<sizeof%> in %qD call is the same " 987 "pointer type %qT as the second source; expected %qT " 988 "or an explicit length", callee, TREE_TYPE (src), 989 TREE_TYPE (TREE_TYPE (src))); 990 return; 991 } 992 } 993 994 } 995 996 /* Warn for unlikely, improbable, or stupid DECL declarations 997 of `main'. */ 998 999 void 1000 check_main_parameter_types (tree decl) 1001 { 1002 function_args_iterator iter; 1003 tree type; 1004 int argct = 0; 1005 1006 FOREACH_FUNCTION_ARGS (TREE_TYPE (decl), type, iter) 1007 { 1008 /* XXX void_type_node belies the abstraction. */ 1009 if (type == void_type_node || type == error_mark_node) 1010 break; 1011 1012 tree t = type; 1013 if (TYPE_ATOMIC (t)) 1014 pedwarn (input_location, OPT_Wmain, 1015 "%<_Atomic%>-qualified parameter type %qT of %q+D", 1016 type, decl); 1017 while (POINTER_TYPE_P (t)) 1018 { 1019 t = TREE_TYPE (t); 1020 if (TYPE_ATOMIC (t)) 1021 pedwarn (input_location, OPT_Wmain, 1022 "%<_Atomic%>-qualified parameter type %qT of %q+D", 1023 type, decl); 1024 } 1025 1026 ++argct; 1027 switch (argct) 1028 { 1029 case 1: 1030 if (TYPE_MAIN_VARIANT (type) != integer_type_node) 1031 pedwarn (input_location, OPT_Wmain, 1032 "first argument of %q+D should be %<int%>", decl); 1033 break; 1034 1035 case 2: 1036 if (TREE_CODE (type) != POINTER_TYPE 1037 || TREE_CODE (TREE_TYPE (type)) != POINTER_TYPE 1038 || (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (type))) 1039 != char_type_node)) 1040 pedwarn (input_location, OPT_Wmain, 1041 "second argument of %q+D should be %<char **%>", decl); 1042 break; 1043 1044 case 3: 1045 if (TREE_CODE (type) != POINTER_TYPE 1046 || TREE_CODE (TREE_TYPE (type)) != POINTER_TYPE 1047 || (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (type))) 1048 != char_type_node)) 1049 pedwarn (input_location, OPT_Wmain, 1050 "third argument of %q+D should probably be " 1051 "%<char **%>", decl); 1052 break; 1053 } 1054 } 1055 1056 /* It is intentional that this message does not mention the third 1057 argument because it's only mentioned in an appendix of the 1058 standard. */ 1059 if (argct > 0 && (argct < 2 || argct > 3)) 1060 pedwarn (input_location, OPT_Wmain, 1061 "%q+D takes only zero or two arguments", decl); 1062 1063 if (stdarg_p (TREE_TYPE (decl))) 1064 pedwarn (input_location, OPT_Wmain, 1065 "%q+D declared as variadic function", decl); 1066 } 1067 1068 /* Warns if the conversion of EXPR to TYPE may alter a value. 1069 This is a helper function for warnings_for_convert_and_check. */ 1070 1071 static void 1072 conversion_warning (location_t loc, tree type, tree expr, tree result) 1073 { 1074 tree expr_type = TREE_TYPE (expr); 1075 enum conversion_safety conversion_kind; 1076 1077 if (!warn_conversion && !warn_sign_conversion && !warn_float_conversion) 1078 return; 1079 1080 /* This may happen, because for LHS op= RHS we preevaluate 1081 RHS and create C_MAYBE_CONST_EXPR <SAVE_EXPR <RHS>>, which 1082 means we could no longer see the code of the EXPR. */ 1083 if (TREE_CODE (expr) == C_MAYBE_CONST_EXPR) 1084 expr = C_MAYBE_CONST_EXPR_EXPR (expr); 1085 if (TREE_CODE (expr) == SAVE_EXPR) 1086 expr = TREE_OPERAND (expr, 0); 1087 1088 switch (TREE_CODE (expr)) 1089 { 1090 case EQ_EXPR: 1091 case NE_EXPR: 1092 case LE_EXPR: 1093 case GE_EXPR: 1094 case LT_EXPR: 1095 case GT_EXPR: 1096 case TRUTH_ANDIF_EXPR: 1097 case TRUTH_ORIF_EXPR: 1098 case TRUTH_AND_EXPR: 1099 case TRUTH_OR_EXPR: 1100 case TRUTH_XOR_EXPR: 1101 case TRUTH_NOT_EXPR: 1102 /* Conversion from boolean to a signed:1 bit-field (which only 1103 can hold the values 0 and -1) doesn't lose information - but 1104 it does change the value. */ 1105 if (TYPE_PRECISION (type) == 1 && !TYPE_UNSIGNED (type)) 1106 warning_at (loc, OPT_Wconversion, 1107 "conversion to %qT from boolean expression", type); 1108 return; 1109 1110 case REAL_CST: 1111 case INTEGER_CST: 1112 case COMPLEX_CST: 1113 { 1114 conversion_kind = unsafe_conversion_p (loc, type, expr, result, true); 1115 int warnopt; 1116 if (conversion_kind == UNSAFE_REAL) 1117 warnopt = OPT_Wfloat_conversion; 1118 else if (conversion_kind) 1119 warnopt = OPT_Wconversion; 1120 else 1121 break; 1122 1123 if (TREE_CODE_CLASS (TREE_CODE (result)) == tcc_constant) 1124 warning_at (loc, warnopt, 1125 "conversion from %qT to %qT changes value from %qE to %qE", 1126 expr_type, type, expr, result); 1127 else 1128 warning_at (loc, warnopt, 1129 "conversion from %qT to %qT changes the value of %qE", 1130 expr_type, type, expr); 1131 break; 1132 } 1133 case COND_EXPR: 1134 { 1135 /* In case of COND_EXPR, we do not care about the type of 1136 COND_EXPR, only about the conversion of each operand. */ 1137 tree op1 = TREE_OPERAND (expr, 1); 1138 tree op2 = TREE_OPERAND (expr, 2); 1139 1140 conversion_warning (loc, type, op1, result); 1141 conversion_warning (loc, type, op2, result); 1142 return; 1143 } 1144 1145 default: /* 'expr' is not a constant. */ 1146 conversion_kind = unsafe_conversion_p (loc, type, expr, result, true); 1147 if (conversion_kind == UNSAFE_IMAGINARY) 1148 warning_at (loc, OPT_Wconversion, 1149 "conversion from %qT to %qT discards imaginary component", 1150 expr_type, type); 1151 else 1152 { 1153 int warnopt; 1154 if (conversion_kind == UNSAFE_REAL) 1155 warnopt = OPT_Wfloat_conversion; 1156 else if (conversion_kind) 1157 warnopt = OPT_Wconversion; 1158 else 1159 break; 1160 warning_at (loc, warnopt, 1161 "conversion from %qT to %qT may change value", 1162 expr_type, type); 1163 } 1164 } 1165 } 1166 1167 /* Produce warnings after a conversion. RESULT is the result of 1168 converting EXPR to TYPE. This is a helper function for 1169 convert_and_check and cp_convert_and_check. */ 1170 1171 void 1172 warnings_for_convert_and_check (location_t loc, tree type, tree expr, 1173 tree result) 1174 { 1175 loc = expansion_point_location_if_in_system_header (loc); 1176 1177 bool cst = TREE_CODE_CLASS (TREE_CODE (result)) == tcc_constant; 1178 1179 tree exprtype = TREE_TYPE (expr); 1180 1181 if (TREE_CODE (expr) == INTEGER_CST 1182 && (TREE_CODE (type) == INTEGER_TYPE 1183 || TREE_CODE (type) == ENUMERAL_TYPE) 1184 && !int_fits_type_p (expr, type)) 1185 { 1186 /* Do not diagnose overflow in a constant expression merely 1187 because a conversion overflowed. */ 1188 if (TREE_OVERFLOW (result)) 1189 TREE_OVERFLOW (result) = TREE_OVERFLOW (expr); 1190 1191 if (TYPE_UNSIGNED (type)) 1192 { 1193 /* This detects cases like converting -129 or 256 to 1194 unsigned char. */ 1195 if (!int_fits_type_p (expr, c_common_signed_type (type))) 1196 { 1197 if (cst) 1198 warning_at (loc, OPT_Woverflow, 1199 (TYPE_UNSIGNED (exprtype) 1200 ? G_("conversion from %qT to %qT " 1201 "changes value from %qE to %qE") 1202 : G_("unsigned conversion from %qT to %qT " 1203 "changes value from %qE to %qE")), 1204 exprtype, type, expr, result); 1205 else 1206 warning_at (loc, OPT_Woverflow, 1207 (TYPE_UNSIGNED (exprtype) 1208 ? G_("conversion from %qT to %qT " 1209 "changes the value of %qE") 1210 : G_("unsigned conversion from %qT to %qT " 1211 "changes the value of %qE")), 1212 exprtype, type, expr); 1213 } 1214 else 1215 conversion_warning (loc, type, expr, result); 1216 } 1217 else if (!int_fits_type_p (expr, c_common_unsigned_type (type))) 1218 { 1219 if (cst) 1220 warning_at (loc, OPT_Woverflow, 1221 "overflow in conversion from %qT to %qT " 1222 "changes value from %qE to %qE", 1223 exprtype, type, expr, result); 1224 else 1225 warning_at (loc, OPT_Woverflow, 1226 "overflow in conversion from %qT to %qT " 1227 "changes the value of %qE", 1228 exprtype, type, expr); 1229 } 1230 /* No warning for converting 0x80000000 to int. */ 1231 else if (pedantic 1232 && (TREE_CODE (exprtype) != INTEGER_TYPE 1233 || TYPE_PRECISION (exprtype) 1234 != TYPE_PRECISION (type))) 1235 { 1236 if (cst) 1237 warning_at (loc, OPT_Woverflow, 1238 "overflow in conversion from %qT to %qT " 1239 "changes value from %qE to %qE", 1240 exprtype, type, expr, result); 1241 else 1242 warning_at (loc, OPT_Woverflow, 1243 "overflow in conversion from %qT to %qT " 1244 "changes the value of %qE", 1245 exprtype, type, expr); 1246 } 1247 else 1248 conversion_warning (loc, type, expr, result); 1249 } 1250 else if ((TREE_CODE (result) == INTEGER_CST 1251 || TREE_CODE (result) == FIXED_CST) && TREE_OVERFLOW (result)) 1252 { 1253 if (cst) 1254 warning_at (loc, OPT_Woverflow, 1255 "overflow in conversion from %qT to %qT " 1256 "changes value from %qE to %qE", 1257 exprtype, type, expr, result); 1258 else 1259 warning_at (loc, OPT_Woverflow, 1260 "overflow in conversion from %qT to %qT " 1261 "changes the value of %qE", 1262 exprtype, type, expr); 1263 } 1264 else 1265 conversion_warning (loc, type, expr, result); 1266 } 1267 1268 /* Subroutines of c_do_switch_warnings, called via splay_tree_foreach. 1269 Used to verify that case values match up with enumerator values. */ 1270 1271 static void 1272 match_case_to_enum_1 (tree key, tree type, tree label) 1273 { 1274 /* Avoid warning about enums that have no enumerators. */ 1275 if (TYPE_VALUES (type) == NULL_TREE) 1276 return; 1277 1278 char buf[WIDE_INT_PRINT_BUFFER_SIZE]; 1279 1280 if (tree_fits_uhwi_p (key)) 1281 print_dec (wi::to_wide (key), buf, UNSIGNED); 1282 else if (tree_fits_shwi_p (key)) 1283 print_dec (wi::to_wide (key), buf, SIGNED); 1284 else 1285 print_hex (wi::to_wide (key), buf); 1286 1287 if (TYPE_NAME (type) == NULL_TREE) 1288 warning_at (DECL_SOURCE_LOCATION (CASE_LABEL (label)), 1289 warn_switch ? OPT_Wswitch : OPT_Wswitch_enum, 1290 "case value %qs not in enumerated type", 1291 buf); 1292 else 1293 warning_at (DECL_SOURCE_LOCATION (CASE_LABEL (label)), 1294 warn_switch ? OPT_Wswitch : OPT_Wswitch_enum, 1295 "case value %qs not in enumerated type %qT", 1296 buf, type); 1297 } 1298 1299 /* Subroutine of c_do_switch_warnings, called via splay_tree_foreach. 1300 Used to verify that case values match up with enumerator values. */ 1301 1302 static int 1303 match_case_to_enum (splay_tree_node node, void *data) 1304 { 1305 tree label = (tree) node->value; 1306 tree type = (tree) data; 1307 1308 /* Skip default case. */ 1309 if (!CASE_LOW (label)) 1310 return 0; 1311 1312 /* If CASE_LOW_SEEN is not set, that means CASE_LOW did not appear 1313 when we did our enum->case scan. Reset our scratch bit after. */ 1314 if (!CASE_LOW_SEEN (label)) 1315 match_case_to_enum_1 (CASE_LOW (label), type, label); 1316 else 1317 CASE_LOW_SEEN (label) = 0; 1318 1319 /* If CASE_HIGH is non-null, we have a range. If CASE_HIGH_SEEN is 1320 not set, that means that CASE_HIGH did not appear when we did our 1321 enum->case scan. Reset our scratch bit after. */ 1322 if (CASE_HIGH (label)) 1323 { 1324 if (!CASE_HIGH_SEEN (label)) 1325 match_case_to_enum_1 (CASE_HIGH (label), type, label); 1326 else 1327 CASE_HIGH_SEEN (label) = 0; 1328 } 1329 1330 return 0; 1331 } 1332 1333 /* Handle -Wswitch*. Called from the front end after parsing the 1334 switch construct. */ 1335 /* ??? Should probably be somewhere generic, since other languages 1336 besides C and C++ would want this. At the moment, however, C/C++ 1337 are the only tree-ssa languages that support enumerations at all, 1338 so the point is moot. */ 1339 1340 void 1341 c_do_switch_warnings (splay_tree cases, location_t switch_location, 1342 tree type, tree cond, bool bool_cond_p, 1343 bool outside_range_p) 1344 { 1345 splay_tree_node default_node; 1346 splay_tree_node node; 1347 tree chain; 1348 1349 if (!warn_switch && !warn_switch_enum && !warn_switch_default 1350 && !warn_switch_bool) 1351 return; 1352 1353 default_node = splay_tree_lookup (cases, (splay_tree_key) NULL); 1354 if (!default_node) 1355 warning_at (switch_location, OPT_Wswitch_default, 1356 "switch missing default case"); 1357 1358 /* There are certain cases where -Wswitch-bool warnings aren't 1359 desirable, such as 1360 switch (boolean) 1361 { 1362 case true: ... 1363 case false: ... 1364 } 1365 so be careful here. */ 1366 if (warn_switch_bool && bool_cond_p) 1367 { 1368 splay_tree_node min_node; 1369 /* If there's a default node, it's also the value with the minimal 1370 key. So look at the penultimate key (if any). */ 1371 if (default_node) 1372 min_node = splay_tree_successor (cases, (splay_tree_key) NULL); 1373 else 1374 min_node = splay_tree_min (cases); 1375 tree min = min_node ? (tree) min_node->key : NULL_TREE; 1376 1377 splay_tree_node max_node = splay_tree_max (cases); 1378 /* This might be a case range, so look at the value with the 1379 maximal key and then check CASE_HIGH. */ 1380 tree max = max_node ? (tree) max_node->value : NULL_TREE; 1381 if (max) 1382 max = CASE_HIGH (max) ? CASE_HIGH (max) : CASE_LOW (max); 1383 1384 /* If there's a case value > 1 or < 0, that is outside bool 1385 range, warn. */ 1386 if (outside_range_p 1387 || (max && wi::gts_p (wi::to_wide (max), 1)) 1388 || (min && wi::lts_p (wi::to_wide (min), 0)) 1389 /* And handle the 1390 switch (boolean) 1391 { 1392 case true: ... 1393 case false: ... 1394 default: ... 1395 } 1396 case, where we want to warn. */ 1397 || (default_node 1398 && max && wi::to_wide (max) == 1 1399 && min && wi::to_wide (min) == 0)) 1400 warning_at (switch_location, OPT_Wswitch_bool, 1401 "switch condition has boolean value"); 1402 } 1403 1404 /* From here on, we only care about enumerated types. */ 1405 if (!type || TREE_CODE (type) != ENUMERAL_TYPE) 1406 return; 1407 1408 /* From here on, we only care about -Wswitch and -Wswitch-enum. */ 1409 if (!warn_switch_enum && !warn_switch) 1410 return; 1411 1412 /* Check the cases. Warn about case values which are not members of 1413 the enumerated type. For -Wswitch-enum, or for -Wswitch when 1414 there is no default case, check that exactly all enumeration 1415 literals are covered by the cases. */ 1416 1417 /* Clearing COND if it is not an integer constant simplifies 1418 the tests inside the loop below. */ 1419 if (TREE_CODE (cond) != INTEGER_CST) 1420 cond = NULL_TREE; 1421 1422 /* The time complexity here is O(N*lg(N)) worst case, but for the 1423 common case of monotonically increasing enumerators, it is 1424 O(N), since the nature of the splay tree will keep the next 1425 element adjacent to the root at all times. */ 1426 1427 for (chain = TYPE_VALUES (type); chain; chain = TREE_CHAIN (chain)) 1428 { 1429 tree value = TREE_VALUE (chain); 1430 if (TREE_CODE (value) == CONST_DECL) 1431 value = DECL_INITIAL (value); 1432 node = splay_tree_lookup (cases, (splay_tree_key) value); 1433 if (node) 1434 { 1435 /* Mark the CASE_LOW part of the case entry as seen. */ 1436 tree label = (tree) node->value; 1437 CASE_LOW_SEEN (label) = 1; 1438 continue; 1439 } 1440 1441 /* Even though there wasn't an exact match, there might be a 1442 case range which includes the enumerator's value. */ 1443 node = splay_tree_predecessor (cases, (splay_tree_key) value); 1444 if (node && CASE_HIGH ((tree) node->value)) 1445 { 1446 tree label = (tree) node->value; 1447 int cmp = tree_int_cst_compare (CASE_HIGH (label), value); 1448 if (cmp >= 0) 1449 { 1450 /* If we match the upper bound exactly, mark the CASE_HIGH 1451 part of the case entry as seen. */ 1452 if (cmp == 0) 1453 CASE_HIGH_SEEN (label) = 1; 1454 continue; 1455 } 1456 } 1457 1458 /* We've now determined that this enumerated literal isn't 1459 handled by the case labels of the switch statement. */ 1460 1461 /* If the switch expression is a constant, we only really care 1462 about whether that constant is handled by the switch. */ 1463 if (cond && tree_int_cst_compare (cond, value)) 1464 continue; 1465 1466 /* If there is a default_node, the only relevant option is 1467 Wswitch-enum. Otherwise, if both are enabled then we prefer 1468 to warn using -Wswitch because -Wswitch is enabled by -Wall 1469 while -Wswitch-enum is explicit. */ 1470 warning_at (switch_location, 1471 (default_node || !warn_switch 1472 ? OPT_Wswitch_enum 1473 : OPT_Wswitch), 1474 "enumeration value %qE not handled in switch", 1475 TREE_PURPOSE (chain)); 1476 } 1477 1478 /* Warn if there are case expressions that don't correspond to 1479 enumerators. This can occur since C and C++ don't enforce 1480 type-checking of assignments to enumeration variables. 1481 1482 The time complexity here is now always O(N) worst case, since 1483 we should have marked both the lower bound and upper bound of 1484 every disjoint case label, with CASE_LOW_SEEN and CASE_HIGH_SEEN 1485 above. This scan also resets those fields. */ 1486 1487 splay_tree_foreach (cases, match_case_to_enum, type); 1488 } 1489 1490 /* Warn for A ?: C expressions (with B omitted) where A is a boolean 1491 expression, because B will always be true. */ 1492 1493 void 1494 warn_for_omitted_condop (location_t location, tree cond) 1495 { 1496 /* In C++ template declarations it can happen that the type is dependent 1497 and not yet known, thus TREE_TYPE (cond) == NULL_TREE. */ 1498 if (truth_value_p (TREE_CODE (cond)) 1499 || (TREE_TYPE (cond) != NULL_TREE 1500 && TREE_CODE (TREE_TYPE (cond)) == BOOLEAN_TYPE)) 1501 warning_at (location, OPT_Wparentheses, 1502 "the omitted middle operand in ?: will always be %<true%>, " 1503 "suggest explicit middle operand"); 1504 } 1505 1506 /* Give an error for storing into ARG, which is 'const'. USE indicates 1507 how ARG was being used. */ 1508 1509 void 1510 readonly_error (location_t loc, tree arg, enum lvalue_use use) 1511 { 1512 gcc_assert (use == lv_assign || use == lv_increment || use == lv_decrement 1513 || use == lv_asm); 1514 /* Using this macro rather than (for example) arrays of messages 1515 ensures that all the format strings are checked at compile 1516 time. */ 1517 #define READONLY_MSG(A, I, D, AS) (use == lv_assign ? (A) \ 1518 : (use == lv_increment ? (I) \ 1519 : (use == lv_decrement ? (D) : (AS)))) 1520 if (TREE_CODE (arg) == COMPONENT_REF) 1521 { 1522 if (TYPE_READONLY (TREE_TYPE (TREE_OPERAND (arg, 0)))) 1523 error_at (loc, READONLY_MSG (G_("assignment of member " 1524 "%qD in read-only object"), 1525 G_("increment of member " 1526 "%qD in read-only object"), 1527 G_("decrement of member " 1528 "%qD in read-only object"), 1529 G_("member %qD in read-only object " 1530 "used as %<asm%> output")), 1531 TREE_OPERAND (arg, 1)); 1532 else 1533 error_at (loc, READONLY_MSG (G_("assignment of read-only member %qD"), 1534 G_("increment of read-only member %qD"), 1535 G_("decrement of read-only member %qD"), 1536 G_("read-only member %qD used as %<asm%> output")), 1537 TREE_OPERAND (arg, 1)); 1538 } 1539 else if (VAR_P (arg)) 1540 error_at (loc, READONLY_MSG (G_("assignment of read-only variable %qD"), 1541 G_("increment of read-only variable %qD"), 1542 G_("decrement of read-only variable %qD"), 1543 G_("read-only variable %qD used as %<asm%> output")), 1544 arg); 1545 else if (TREE_CODE (arg) == PARM_DECL) 1546 error_at (loc, READONLY_MSG (G_("assignment of read-only parameter %qD"), 1547 G_("increment of read-only parameter %qD"), 1548 G_("decrement of read-only parameter %qD"), 1549 G_("read-only parameter %qD use as %<asm%> output")), 1550 arg); 1551 else if (TREE_CODE (arg) == RESULT_DECL) 1552 { 1553 gcc_assert (c_dialect_cxx ()); 1554 error_at (loc, READONLY_MSG (G_("assignment of " 1555 "read-only named return value %qD"), 1556 G_("increment of " 1557 "read-only named return value %qD"), 1558 G_("decrement of " 1559 "read-only named return value %qD"), 1560 G_("read-only named return value %qD " 1561 "used as %<asm%>output")), 1562 arg); 1563 } 1564 else if (TREE_CODE (arg) == FUNCTION_DECL) 1565 error_at (loc, READONLY_MSG (G_("assignment of function %qD"), 1566 G_("increment of function %qD"), 1567 G_("decrement of function %qD"), 1568 G_("function %qD used as %<asm%> output")), 1569 arg); 1570 else 1571 error_at (loc, READONLY_MSG (G_("assignment of read-only location %qE"), 1572 G_("increment of read-only location %qE"), 1573 G_("decrement of read-only location %qE"), 1574 G_("read-only location %qE used as %<asm%> output")), 1575 arg); 1576 } 1577 1578 /* Print an error message for an invalid lvalue. USE says 1579 how the lvalue is being used and so selects the error message. LOC 1580 is the location for the error. */ 1581 1582 void 1583 lvalue_error (location_t loc, enum lvalue_use use) 1584 { 1585 switch (use) 1586 { 1587 case lv_assign: 1588 error_at (loc, "lvalue required as left operand of assignment"); 1589 break; 1590 case lv_increment: 1591 error_at (loc, "lvalue required as increment operand"); 1592 break; 1593 case lv_decrement: 1594 error_at (loc, "lvalue required as decrement operand"); 1595 break; 1596 case lv_addressof: 1597 error_at (loc, "lvalue required as unary %<&%> operand"); 1598 break; 1599 case lv_asm: 1600 error_at (loc, "lvalue required in asm statement"); 1601 break; 1602 default: 1603 gcc_unreachable (); 1604 } 1605 } 1606 1607 /* Print an error message for an invalid indirection of type TYPE. 1608 ERRSTRING is the name of the operator for the indirection. */ 1609 1610 void 1611 invalid_indirection_error (location_t loc, tree type, ref_operator errstring) 1612 { 1613 switch (errstring) 1614 { 1615 case RO_NULL: 1616 gcc_assert (c_dialect_cxx ()); 1617 error_at (loc, "invalid type argument (have %qT)", type); 1618 break; 1619 case RO_ARRAY_INDEXING: 1620 error_at (loc, 1621 "invalid type argument of array indexing (have %qT)", 1622 type); 1623 break; 1624 case RO_UNARY_STAR: 1625 error_at (loc, 1626 "invalid type argument of unary %<*%> (have %qT)", 1627 type); 1628 break; 1629 case RO_ARROW: 1630 error_at (loc, 1631 "invalid type argument of %<->%> (have %qT)", 1632 type); 1633 break; 1634 case RO_ARROW_STAR: 1635 error_at (loc, 1636 "invalid type argument of %<->*%> (have %qT)", 1637 type); 1638 break; 1639 case RO_IMPLICIT_CONVERSION: 1640 error_at (loc, 1641 "invalid type argument of implicit conversion (have %qT)", 1642 type); 1643 break; 1644 default: 1645 gcc_unreachable (); 1646 } 1647 } 1648 1649 /* Subscripting with type char is likely to lose on a machine where 1650 chars are signed. So warn on any machine, but optionally. Don't 1651 warn for unsigned char since that type is safe. Don't warn for 1652 signed char because anyone who uses that must have done so 1653 deliberately. Furthermore, we reduce the false positive load by 1654 warning only for non-constant value of type char. */ 1655 1656 void 1657 warn_array_subscript_with_type_char (location_t loc, tree index) 1658 { 1659 if (TYPE_MAIN_VARIANT (TREE_TYPE (index)) == char_type_node 1660 && TREE_CODE (index) != INTEGER_CST) 1661 warning_at (loc, OPT_Wchar_subscripts, 1662 "array subscript has type %<char%>"); 1663 } 1664 1665 /* Implement -Wparentheses for the unexpected C precedence rules, to 1666 cover cases like x + y << z which readers are likely to 1667 misinterpret. We have seen an expression in which CODE is a binary 1668 operator used to combine expressions ARG_LEFT and ARG_RIGHT, which 1669 before folding had CODE_LEFT and CODE_RIGHT. CODE_LEFT and 1670 CODE_RIGHT may be ERROR_MARK, which means that that side of the 1671 expression was not formed using a binary or unary operator, or it 1672 was enclosed in parentheses. */ 1673 1674 void 1675 warn_about_parentheses (location_t loc, enum tree_code code, 1676 enum tree_code code_left, tree arg_left, 1677 enum tree_code code_right, tree arg_right) 1678 { 1679 if (!warn_parentheses) 1680 return; 1681 1682 /* This macro tests that the expression ARG with original tree code 1683 CODE appears to be a boolean expression. or the result of folding a 1684 boolean expression. */ 1685 #define APPEARS_TO_BE_BOOLEAN_EXPR_P(CODE, ARG) \ 1686 (truth_value_p (TREE_CODE (ARG)) \ 1687 || TREE_CODE (TREE_TYPE (ARG)) == BOOLEAN_TYPE \ 1688 /* Folding may create 0 or 1 integers from other expressions. */ \ 1689 || ((CODE) != INTEGER_CST \ 1690 && (integer_onep (ARG) || integer_zerop (ARG)))) 1691 1692 switch (code) 1693 { 1694 case LSHIFT_EXPR: 1695 if (code_left == PLUS_EXPR) 1696 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1697 "suggest parentheses around %<+%> inside %<<<%>"); 1698 else if (code_right == PLUS_EXPR) 1699 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1700 "suggest parentheses around %<+%> inside %<<<%>"); 1701 else if (code_left == MINUS_EXPR) 1702 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1703 "suggest parentheses around %<-%> inside %<<<%>"); 1704 else if (code_right == MINUS_EXPR) 1705 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1706 "suggest parentheses around %<-%> inside %<<<%>"); 1707 return; 1708 1709 case RSHIFT_EXPR: 1710 if (code_left == PLUS_EXPR) 1711 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1712 "suggest parentheses around %<+%> inside %<>>%>"); 1713 else if (code_right == PLUS_EXPR) 1714 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1715 "suggest parentheses around %<+%> inside %<>>%>"); 1716 else if (code_left == MINUS_EXPR) 1717 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1718 "suggest parentheses around %<-%> inside %<>>%>"); 1719 else if (code_right == MINUS_EXPR) 1720 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1721 "suggest parentheses around %<-%> inside %<>>%>"); 1722 return; 1723 1724 case TRUTH_ORIF_EXPR: 1725 if (code_left == TRUTH_ANDIF_EXPR) 1726 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1727 "suggest parentheses around %<&&%> within %<||%>"); 1728 else if (code_right == TRUTH_ANDIF_EXPR) 1729 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1730 "suggest parentheses around %<&&%> within %<||%>"); 1731 return; 1732 1733 case BIT_IOR_EXPR: 1734 if (code_left == BIT_AND_EXPR || code_left == BIT_XOR_EXPR 1735 || code_left == PLUS_EXPR || code_left == MINUS_EXPR) 1736 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1737 "suggest parentheses around arithmetic in operand of %<|%>"); 1738 else if (code_right == BIT_AND_EXPR || code_right == BIT_XOR_EXPR 1739 || code_right == PLUS_EXPR || code_right == MINUS_EXPR) 1740 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1741 "suggest parentheses around arithmetic in operand of %<|%>"); 1742 /* Check cases like x|y==z */ 1743 else if (TREE_CODE_CLASS (code_left) == tcc_comparison) 1744 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1745 "suggest parentheses around comparison in operand of %<|%>"); 1746 else if (TREE_CODE_CLASS (code_right) == tcc_comparison) 1747 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1748 "suggest parentheses around comparison in operand of %<|%>"); 1749 /* Check cases like !x | y */ 1750 else if (code_left == TRUTH_NOT_EXPR 1751 && !APPEARS_TO_BE_BOOLEAN_EXPR_P (code_right, arg_right)) 1752 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1753 "suggest parentheses around operand of " 1754 "%<!%> or change %<|%> to %<||%> or %<!%> to %<~%>"); 1755 return; 1756 1757 case BIT_XOR_EXPR: 1758 if (code_left == BIT_AND_EXPR 1759 || code_left == PLUS_EXPR || code_left == MINUS_EXPR) 1760 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1761 "suggest parentheses around arithmetic in operand of %<^%>"); 1762 else if (code_right == BIT_AND_EXPR 1763 || code_right == PLUS_EXPR || code_right == MINUS_EXPR) 1764 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1765 "suggest parentheses around arithmetic in operand of %<^%>"); 1766 /* Check cases like x^y==z */ 1767 else if (TREE_CODE_CLASS (code_left) == tcc_comparison) 1768 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1769 "suggest parentheses around comparison in operand of %<^%>"); 1770 else if (TREE_CODE_CLASS (code_right) == tcc_comparison) 1771 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1772 "suggest parentheses around comparison in operand of %<^%>"); 1773 return; 1774 1775 case BIT_AND_EXPR: 1776 if (code_left == PLUS_EXPR) 1777 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1778 "suggest parentheses around %<+%> in operand of %<&%>"); 1779 else if (code_right == PLUS_EXPR) 1780 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1781 "suggest parentheses around %<+%> in operand of %<&%>"); 1782 else if (code_left == MINUS_EXPR) 1783 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1784 "suggest parentheses around %<-%> in operand of %<&%>"); 1785 else if (code_right == MINUS_EXPR) 1786 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1787 "suggest parentheses around %<-%> in operand of %<&%>"); 1788 /* Check cases like x&y==z */ 1789 else if (TREE_CODE_CLASS (code_left) == tcc_comparison) 1790 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1791 "suggest parentheses around comparison in operand of %<&%>"); 1792 else if (TREE_CODE_CLASS (code_right) == tcc_comparison) 1793 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1794 "suggest parentheses around comparison in operand of %<&%>"); 1795 /* Check cases like !x & y */ 1796 else if (code_left == TRUTH_NOT_EXPR 1797 && !APPEARS_TO_BE_BOOLEAN_EXPR_P (code_right, arg_right)) 1798 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1799 "suggest parentheses around operand of " 1800 "%<!%> or change %<&%> to %<&&%> or %<!%> to %<~%>"); 1801 return; 1802 1803 case EQ_EXPR: 1804 if (TREE_CODE_CLASS (code_left) == tcc_comparison) 1805 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1806 "suggest parentheses around comparison in operand of %<==%>"); 1807 else if (TREE_CODE_CLASS (code_right) == tcc_comparison) 1808 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1809 "suggest parentheses around comparison in operand of %<==%>"); 1810 return; 1811 case NE_EXPR: 1812 if (TREE_CODE_CLASS (code_left) == tcc_comparison) 1813 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1814 "suggest parentheses around comparison in operand of %<!=%>"); 1815 else if (TREE_CODE_CLASS (code_right) == tcc_comparison) 1816 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1817 "suggest parentheses around comparison in operand of %<!=%>"); 1818 return; 1819 1820 default: 1821 if (TREE_CODE_CLASS (code) == tcc_comparison) 1822 { 1823 if (TREE_CODE_CLASS (code_left) == tcc_comparison 1824 && code_left != NE_EXPR && code_left != EQ_EXPR 1825 && INTEGRAL_TYPE_P (TREE_TYPE (arg_left))) 1826 warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses, 1827 "comparisons like %<X<=Y<=Z%> do not " 1828 "have their mathematical meaning"); 1829 else if (TREE_CODE_CLASS (code_right) == tcc_comparison 1830 && code_right != NE_EXPR && code_right != EQ_EXPR 1831 && INTEGRAL_TYPE_P (TREE_TYPE (arg_right))) 1832 warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses, 1833 "comparisons like %<X<=Y<=Z%> do not " 1834 "have their mathematical meaning"); 1835 } 1836 return; 1837 } 1838 #undef NOT_A_BOOLEAN_EXPR_P 1839 } 1840 1841 /* If LABEL (a LABEL_DECL) has not been used, issue a warning. */ 1842 1843 void 1844 warn_for_unused_label (tree label) 1845 { 1846 if (!TREE_USED (label)) 1847 { 1848 if (DECL_INITIAL (label)) 1849 warning (OPT_Wunused_label, "label %q+D defined but not used", label); 1850 else 1851 warning (OPT_Wunused_label, "label %q+D declared but not defined", label); 1852 } 1853 else if (asan_sanitize_use_after_scope ()) 1854 { 1855 if (asan_used_labels == NULL) 1856 asan_used_labels = new hash_set<tree> (16); 1857 1858 asan_used_labels->add (label); 1859 } 1860 } 1861 1862 /* Warn for division by zero according to the value of DIVISOR. LOC 1863 is the location of the division operator. */ 1864 1865 void 1866 warn_for_div_by_zero (location_t loc, tree divisor) 1867 { 1868 /* If DIVISOR is zero, and has integral or fixed-point type, issue a warning 1869 about division by zero. Do not issue a warning if DIVISOR has a 1870 floating-point type, since we consider 0.0/0.0 a valid way of 1871 generating a NaN. */ 1872 if (c_inhibit_evaluation_warnings == 0 1873 && (integer_zerop (divisor) || fixed_zerop (divisor))) 1874 warning_at (loc, OPT_Wdiv_by_zero, "division by zero"); 1875 } 1876 1877 /* Warn for patterns where memset appears to be used incorrectly. The 1878 warning location should be LOC. ARG0, and ARG2 are the first and 1879 last arguments to the call, while LITERAL_ZERO_MASK has a 1 bit for 1880 each argument that was a literal zero. */ 1881 1882 void 1883 warn_for_memset (location_t loc, tree arg0, tree arg2, 1884 int literal_zero_mask) 1885 { 1886 arg0 = fold_for_warn (arg0); 1887 arg2 = fold_for_warn (arg2); 1888 1889 if (warn_memset_transposed_args 1890 && integer_zerop (arg2) 1891 && (literal_zero_mask & (1 << 2)) != 0 1892 && (literal_zero_mask & (1 << 1)) == 0) 1893 warning_at (loc, OPT_Wmemset_transposed_args, 1894 "%<memset%> used with constant zero length " 1895 "parameter; this could be due to transposed " 1896 "parameters"); 1897 1898 if (warn_memset_elt_size && TREE_CODE (arg2) == INTEGER_CST) 1899 { 1900 STRIP_NOPS (arg0); 1901 if (TREE_CODE (arg0) == ADDR_EXPR) 1902 arg0 = TREE_OPERAND (arg0, 0); 1903 tree type = TREE_TYPE (arg0); 1904 if (type != NULL_TREE && TREE_CODE (type) == ARRAY_TYPE) 1905 { 1906 tree elt_type = TREE_TYPE (type); 1907 tree domain = TYPE_DOMAIN (type); 1908 if (COMPLETE_TYPE_P (elt_type) 1909 && !integer_onep (TYPE_SIZE_UNIT (elt_type)) 1910 && domain != NULL_TREE 1911 && TYPE_MAX_VALUE (domain) 1912 && TYPE_MIN_VALUE (domain) 1913 && integer_zerop (TYPE_MIN_VALUE (domain)) 1914 && integer_onep (fold_build2 (MINUS_EXPR, domain, 1915 arg2, 1916 TYPE_MAX_VALUE (domain)))) 1917 warning_at (loc, OPT_Wmemset_elt_size, 1918 "%<memset%> used with length equal to " 1919 "number of elements without multiplication " 1920 "by element size"); 1921 } 1922 } 1923 } 1924 1925 /* Subroutine of build_binary_op. Give warnings for comparisons 1926 between signed and unsigned quantities that may fail. Do the 1927 checking based on the original operand trees ORIG_OP0 and ORIG_OP1, 1928 so that casts will be considered, but default promotions won't 1929 be. 1930 1931 LOCATION is the location of the comparison operator. 1932 1933 The arguments of this function map directly to local variables 1934 of build_binary_op. */ 1935 1936 void 1937 warn_for_sign_compare (location_t location, 1938 tree orig_op0, tree orig_op1, 1939 tree op0, tree op1, 1940 tree result_type, enum tree_code resultcode) 1941 { 1942 if (error_operand_p (orig_op0) || error_operand_p (orig_op1)) 1943 return; 1944 1945 int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0)); 1946 int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1)); 1947 int unsignedp0, unsignedp1; 1948 1949 /* In C++, check for comparison of different enum types. */ 1950 if (c_dialect_cxx() 1951 && TREE_CODE (TREE_TYPE (orig_op0)) == ENUMERAL_TYPE 1952 && TREE_CODE (TREE_TYPE (orig_op1)) == ENUMERAL_TYPE 1953 && TYPE_MAIN_VARIANT (TREE_TYPE (orig_op0)) 1954 != TYPE_MAIN_VARIANT (TREE_TYPE (orig_op1))) 1955 { 1956 warning_at (location, 1957 OPT_Wsign_compare, "comparison between types %qT and %qT", 1958 TREE_TYPE (orig_op0), TREE_TYPE (orig_op1)); 1959 } 1960 1961 /* Do not warn if the comparison is being done in a signed type, 1962 since the signed type will only be chosen if it can represent 1963 all the values of the unsigned type. */ 1964 if (!TYPE_UNSIGNED (result_type)) 1965 /* OK */; 1966 /* Do not warn if both operands are unsigned. */ 1967 else if (op0_signed == op1_signed) 1968 /* OK */; 1969 else 1970 { 1971 tree sop, uop, base_type; 1972 bool ovf; 1973 1974 if (op0_signed) 1975 sop = orig_op0, uop = orig_op1; 1976 else 1977 sop = orig_op1, uop = orig_op0; 1978 1979 STRIP_TYPE_NOPS (sop); 1980 STRIP_TYPE_NOPS (uop); 1981 base_type = (TREE_CODE (result_type) == COMPLEX_TYPE 1982 ? TREE_TYPE (result_type) : result_type); 1983 1984 /* Do not warn if the signed quantity is an unsuffixed integer 1985 literal (or some static constant expression involving such 1986 literals or a conditional expression involving such literals) 1987 and it is non-negative. */ 1988 if (tree_expr_nonnegative_warnv_p (sop, &ovf)) 1989 /* OK */; 1990 /* Do not warn if the comparison is an equality operation, the 1991 unsigned quantity is an integral constant, and it would fit 1992 in the result if the result were signed. */ 1993 else if (TREE_CODE (uop) == INTEGER_CST 1994 && (resultcode == EQ_EXPR || resultcode == NE_EXPR) 1995 && int_fits_type_p (uop, c_common_signed_type (base_type))) 1996 /* OK */; 1997 /* In C, do not warn if the unsigned quantity is an enumeration 1998 constant and its maximum value would fit in the result if the 1999 result were signed. */ 2000 else if (!c_dialect_cxx() && TREE_CODE (uop) == INTEGER_CST 2001 && TREE_CODE (TREE_TYPE (uop)) == ENUMERAL_TYPE 2002 && int_fits_type_p (TYPE_MAX_VALUE (TREE_TYPE (uop)), 2003 c_common_signed_type (base_type))) 2004 /* OK */; 2005 else 2006 warning_at (location, OPT_Wsign_compare, 2007 "comparison of integer expressions of different " 2008 "signedness: %qT and %qT", TREE_TYPE (orig_op0), 2009 TREE_TYPE (orig_op1)); 2010 } 2011 2012 /* Warn if two unsigned values are being compared in a size larger 2013 than their original size, and one (and only one) is the result of 2014 a `~' operator. This comparison will always fail. 2015 2016 Also warn if one operand is a constant, and the constant does not 2017 have all bits set that are set in the ~ operand when it is 2018 extended. */ 2019 2020 op0 = c_common_get_narrower (op0, &unsignedp0); 2021 op1 = c_common_get_narrower (op1, &unsignedp1); 2022 2023 if ((TREE_CODE (op0) == BIT_NOT_EXPR) 2024 ^ (TREE_CODE (op1) == BIT_NOT_EXPR)) 2025 { 2026 if (TREE_CODE (op0) == BIT_NOT_EXPR) 2027 op0 = c_common_get_narrower (TREE_OPERAND (op0, 0), &unsignedp0); 2028 if (TREE_CODE (op1) == BIT_NOT_EXPR) 2029 op1 = c_common_get_narrower (TREE_OPERAND (op1, 0), &unsignedp1); 2030 2031 if (tree_fits_shwi_p (op0) || tree_fits_shwi_p (op1)) 2032 { 2033 tree primop; 2034 HOST_WIDE_INT constant, mask; 2035 int unsignedp; 2036 unsigned int bits; 2037 2038 if (tree_fits_shwi_p (op0)) 2039 { 2040 primop = op1; 2041 unsignedp = unsignedp1; 2042 constant = tree_to_shwi (op0); 2043 } 2044 else 2045 { 2046 primop = op0; 2047 unsignedp = unsignedp0; 2048 constant = tree_to_shwi (op1); 2049 } 2050 2051 bits = TYPE_PRECISION (TREE_TYPE (primop)); 2052 if (bits < TYPE_PRECISION (result_type) 2053 && bits < HOST_BITS_PER_LONG && unsignedp) 2054 { 2055 mask = HOST_WIDE_INT_M1U << bits; 2056 if ((mask & constant) != mask) 2057 { 2058 if (constant == 0) 2059 warning_at (location, OPT_Wsign_compare, 2060 "promoted ~unsigned is always non-zero"); 2061 else 2062 warning_at (location, OPT_Wsign_compare, 2063 "comparison of promoted ~unsigned with constant"); 2064 } 2065 } 2066 } 2067 else if (unsignedp0 && unsignedp1 2068 && (TYPE_PRECISION (TREE_TYPE (op0)) 2069 < TYPE_PRECISION (result_type)) 2070 && (TYPE_PRECISION (TREE_TYPE (op1)) 2071 < TYPE_PRECISION (result_type))) 2072 warning_at (location, OPT_Wsign_compare, 2073 "comparison of promoted ~unsigned with unsigned"); 2074 } 2075 } 2076 2077 /* RESULT_TYPE is the result of converting TYPE1 and TYPE2 to a common 2078 type via c_common_type. If -Wdouble-promotion is in use, and the 2079 conditions for warning have been met, issue a warning. GMSGID is 2080 the warning message. It must have two %T specifiers for the type 2081 that was converted (generally "float") and the type to which it was 2082 converted (generally "double), respectively. LOC is the location 2083 to which the warning should refer. */ 2084 2085 void 2086 do_warn_double_promotion (tree result_type, tree type1, tree type2, 2087 const char *gmsgid, location_t loc) 2088 { 2089 tree source_type; 2090 2091 if (!warn_double_promotion) 2092 return; 2093 /* If the conversion will not occur at run-time, there is no need to 2094 warn about it. */ 2095 if (c_inhibit_evaluation_warnings) 2096 return; 2097 /* If an invalid conversion has occured, don't warn. */ 2098 if (result_type == error_mark_node) 2099 return; 2100 if (TYPE_MAIN_VARIANT (result_type) != double_type_node 2101 && TYPE_MAIN_VARIANT (result_type) != complex_double_type_node) 2102 return; 2103 if (TYPE_MAIN_VARIANT (type1) == float_type_node 2104 || TYPE_MAIN_VARIANT (type1) == complex_float_type_node) 2105 source_type = type1; 2106 else if (TYPE_MAIN_VARIANT (type2) == float_type_node 2107 || TYPE_MAIN_VARIANT (type2) == complex_float_type_node) 2108 source_type = type2; 2109 else 2110 return; 2111 warning_at (loc, OPT_Wdouble_promotion, gmsgid, source_type, result_type); 2112 } 2113 2114 /* Possibly warn about unused parameters. */ 2115 2116 void 2117 do_warn_unused_parameter (tree fn) 2118 { 2119 tree decl; 2120 2121 for (decl = DECL_ARGUMENTS (fn); 2122 decl; decl = DECL_CHAIN (decl)) 2123 if (!TREE_USED (decl) && TREE_CODE (decl) == PARM_DECL 2124 && DECL_NAME (decl) && !DECL_ARTIFICIAL (decl) 2125 && !TREE_NO_WARNING (decl)) 2126 warning_at (DECL_SOURCE_LOCATION (decl), OPT_Wunused_parameter, 2127 "unused parameter %qD", decl); 2128 } 2129 2130 /* If DECL is a typedef that is declared in the current function, 2131 record it for the purpose of -Wunused-local-typedefs. */ 2132 2133 void 2134 record_locally_defined_typedef (tree decl) 2135 { 2136 struct c_language_function *l; 2137 2138 if (!warn_unused_local_typedefs 2139 || cfun == NULL 2140 /* if this is not a locally defined typedef then we are not 2141 interested. */ 2142 || !is_typedef_decl (decl) 2143 || !decl_function_context (decl)) 2144 return; 2145 2146 l = (struct c_language_function *) cfun->language; 2147 vec_safe_push (l->local_typedefs, decl); 2148 } 2149 2150 /* If T is a TYPE_DECL declared locally, mark it as used. */ 2151 2152 void 2153 maybe_record_typedef_use (tree t) 2154 { 2155 if (!is_typedef_decl (t)) 2156 return; 2157 2158 TREE_USED (t) = true; 2159 } 2160 2161 /* Warn if there are some unused locally defined typedefs in the 2162 current function. */ 2163 2164 void 2165 maybe_warn_unused_local_typedefs (void) 2166 { 2167 int i; 2168 tree decl; 2169 /* The number of times we have emitted -Wunused-local-typedefs 2170 warnings. If this is different from errorcount, that means some 2171 unrelated errors have been issued. In which case, we'll avoid 2172 emitting "unused-local-typedefs" warnings. */ 2173 static int unused_local_typedefs_warn_count; 2174 struct c_language_function *l; 2175 2176 if (cfun == NULL) 2177 return; 2178 2179 if ((l = (struct c_language_function *) cfun->language) == NULL) 2180 return; 2181 2182 if (warn_unused_local_typedefs 2183 && errorcount == unused_local_typedefs_warn_count) 2184 { 2185 FOR_EACH_VEC_SAFE_ELT (l->local_typedefs, i, decl) 2186 if (!TREE_USED (decl)) 2187 warning_at (DECL_SOURCE_LOCATION (decl), 2188 OPT_Wunused_local_typedefs, 2189 "typedef %qD locally defined but not used", decl); 2190 unused_local_typedefs_warn_count = errorcount; 2191 } 2192 2193 vec_free (l->local_typedefs); 2194 } 2195 2196 /* If we're creating an if-else-if condition chain, first see if we 2197 already have this COND in the CHAIN. If so, warn and don't add COND 2198 into the vector, otherwise add the COND there. LOC is the location 2199 of COND. */ 2200 2201 void 2202 warn_duplicated_cond_add_or_warn (location_t loc, tree cond, vec<tree> **chain) 2203 { 2204 /* No chain has been created yet. Do nothing. */ 2205 if (*chain == NULL) 2206 return; 2207 2208 if (TREE_SIDE_EFFECTS (cond)) 2209 { 2210 /* Uh-oh! This condition has a side-effect, thus invalidates 2211 the whole chain. */ 2212 delete *chain; 2213 *chain = NULL; 2214 return; 2215 } 2216 2217 unsigned int ix; 2218 tree t; 2219 bool found = false; 2220 FOR_EACH_VEC_ELT (**chain, ix, t) 2221 if (operand_equal_p (cond, t, 0)) 2222 { 2223 if (warning_at (loc, OPT_Wduplicated_cond, 2224 "duplicated %<if%> condition")) 2225 inform (EXPR_LOCATION (t), "previously used here"); 2226 found = true; 2227 break; 2228 } 2229 2230 if (!found 2231 && !CONSTANT_CLASS_P (cond) 2232 /* Don't infinitely grow the chain. */ 2233 && (*chain)->length () < 512) 2234 (*chain)->safe_push (cond); 2235 } 2236 2237 /* Check and possibly warn if two declarations have contradictory 2238 attributes, such as always_inline vs. noinline. */ 2239 2240 bool 2241 diagnose_mismatched_attributes (tree olddecl, tree newdecl) 2242 { 2243 bool warned = false; 2244 2245 tree a1 = lookup_attribute ("optimize", DECL_ATTRIBUTES (olddecl)); 2246 tree a2 = lookup_attribute ("optimize", DECL_ATTRIBUTES (newdecl)); 2247 /* An optimization attribute applied on a declaration after the 2248 definition is likely not what the user wanted. */ 2249 if (a2 != NULL_TREE 2250 && DECL_SAVED_TREE (olddecl) != NULL_TREE 2251 && (a1 == NULL_TREE || !attribute_list_equal (a1, a2))) 2252 warned |= warning (OPT_Wattributes, 2253 "optimization attribute on %qD follows " 2254 "definition but the attribute doesn%'t match", 2255 newdecl); 2256 2257 /* Diagnose inline __attribute__ ((noinline)) which is silly. */ 2258 if (DECL_DECLARED_INLINE_P (newdecl) 2259 && DECL_UNINLINABLE (olddecl) 2260 && lookup_attribute ("noinline", DECL_ATTRIBUTES (olddecl))) 2261 warned |= warning (OPT_Wattributes, "inline declaration of %qD follows " 2262 "declaration with attribute %qs", newdecl, "noinline"); 2263 else if (DECL_DECLARED_INLINE_P (olddecl) 2264 && DECL_UNINLINABLE (newdecl) 2265 && lookup_attribute ("noinline", DECL_ATTRIBUTES (newdecl))) 2266 warned |= warning (OPT_Wattributes, "declaration of %q+D with attribute " 2267 "%qs follows inline declaration", newdecl, "noinline"); 2268 2269 return warned; 2270 } 2271 2272 /* Warn if signed left shift overflows. We don't warn 2273 about left-shifting 1 into the sign bit in C++14; cf. 2274 <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3367.html#1457> 2275 LOC is a location of the shift; OP0 and OP1 are the operands. 2276 Return true if an overflow is detected, false otherwise. */ 2277 2278 bool 2279 maybe_warn_shift_overflow (location_t loc, tree op0, tree op1) 2280 { 2281 if (TREE_CODE (op0) != INTEGER_CST 2282 || TREE_CODE (op1) != INTEGER_CST) 2283 return false; 2284 2285 tree type0 = TREE_TYPE (op0); 2286 unsigned int prec0 = TYPE_PRECISION (type0); 2287 2288 /* Left-hand operand must be signed. */ 2289 if (TYPE_UNSIGNED (type0)) 2290 return false; 2291 2292 unsigned int min_prec = (wi::min_precision (wi::to_wide (op0), SIGNED) 2293 + TREE_INT_CST_LOW (op1)); 2294 /* Handle the case of left-shifting 1 into the sign bit. 2295 * However, shifting 1 _out_ of the sign bit, as in 2296 * INT_MIN << 1, is considered an overflow. 2297 */ 2298 if (!tree_int_cst_sign_bit(op0) && min_prec == prec0 + 1) 2299 { 2300 /* Never warn for C++14 onwards. */ 2301 if (cxx_dialect >= cxx14) 2302 return false; 2303 /* Otherwise only if -Wshift-overflow=2. But return 2304 true to signal an overflow for the sake of integer 2305 constant expressions. */ 2306 if (warn_shift_overflow < 2) 2307 return true; 2308 } 2309 2310 bool overflowed = min_prec > prec0; 2311 if (overflowed && c_inhibit_evaluation_warnings == 0) 2312 warning_at (loc, OPT_Wshift_overflow_, 2313 "result of %qE requires %u bits to represent, " 2314 "but %qT only has %u bits", 2315 build2_loc (loc, LSHIFT_EXPR, type0, op0, op1), 2316 min_prec, type0, prec0); 2317 2318 return overflowed; 2319 } 2320 2321 /* Warn about boolean expression compared with an integer value different 2322 from true/false. Warns also e.g. about "(i1 == i2) == 2". 2323 LOC is the location of the comparison, CODE is its code, OP0 and OP1 2324 are the operands of the comparison. The caller must ensure that 2325 either operand is a boolean expression. */ 2326 2327 void 2328 maybe_warn_bool_compare (location_t loc, enum tree_code code, tree op0, 2329 tree op1) 2330 { 2331 if (TREE_CODE_CLASS (code) != tcc_comparison) 2332 return; 2333 2334 tree f, cst; 2335 if (f = fold_for_warn (op0), 2336 TREE_CODE (f) == INTEGER_CST) 2337 cst = op0 = f; 2338 else if (f = fold_for_warn (op1), 2339 TREE_CODE (f) == INTEGER_CST) 2340 cst = op1 = f; 2341 else 2342 return; 2343 2344 if (!integer_zerop (cst) && !integer_onep (cst)) 2345 { 2346 int sign = (TREE_CODE (op0) == INTEGER_CST 2347 ? tree_int_cst_sgn (cst) : -tree_int_cst_sgn (cst)); 2348 if (code == EQ_EXPR 2349 || ((code == GT_EXPR || code == GE_EXPR) && sign < 0) 2350 || ((code == LT_EXPR || code == LE_EXPR) && sign > 0)) 2351 warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE " 2352 "with boolean expression is always false", cst); 2353 else 2354 warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE " 2355 "with boolean expression is always true", cst); 2356 } 2357 else if (integer_zerop (cst) || integer_onep (cst)) 2358 { 2359 /* If the non-constant operand isn't of a boolean type, we 2360 don't want to warn here. */ 2361 tree noncst = TREE_CODE (op0) == INTEGER_CST ? op1 : op0; 2362 /* Handle booleans promoted to integers. */ 2363 if (bool_promoted_to_int_p (noncst)) 2364 /* Warn. */; 2365 else if (TREE_CODE (TREE_TYPE (noncst)) != BOOLEAN_TYPE 2366 && !truth_value_p (TREE_CODE (noncst))) 2367 return; 2368 /* Do some magic to get the right diagnostics. */ 2369 bool flag = TREE_CODE (op0) == INTEGER_CST; 2370 flag = integer_zerop (cst) ? flag : !flag; 2371 if ((code == GE_EXPR && !flag) || (code == LE_EXPR && flag)) 2372 warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE " 2373 "with boolean expression is always true", cst); 2374 else if ((code == LT_EXPR && !flag) || (code == GT_EXPR && flag)) 2375 warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE " 2376 "with boolean expression is always false", cst); 2377 } 2378 } 2379 2380 /* Warn if an argument at position param_pos is passed to a 2381 restrict-qualified param, and it aliases with another argument. 2382 Return true if a warning has been issued. */ 2383 2384 bool 2385 warn_for_restrict (unsigned param_pos, tree *argarray, unsigned nargs) 2386 { 2387 tree arg = argarray[param_pos]; 2388 if (TREE_VISITED (arg) || integer_zerop (arg)) 2389 return false; 2390 2391 location_t loc = EXPR_LOC_OR_LOC (arg, input_location); 2392 gcc_rich_location richloc (loc); 2393 2394 unsigned i; 2395 auto_vec<int, 16> arg_positions; 2396 2397 for (i = 0; i < nargs; i++) 2398 { 2399 if (i == param_pos) 2400 continue; 2401 2402 tree current_arg = argarray[i]; 2403 if (operand_equal_p (arg, current_arg, 0)) 2404 { 2405 TREE_VISITED (current_arg) = 1; 2406 arg_positions.safe_push (i + 1); 2407 } 2408 } 2409 2410 if (arg_positions.is_empty ()) 2411 return false; 2412 2413 int pos; 2414 FOR_EACH_VEC_ELT (arg_positions, i, pos) 2415 { 2416 arg = argarray[pos - 1]; 2417 if (EXPR_HAS_LOCATION (arg)) 2418 richloc.add_range (EXPR_LOCATION (arg), false); 2419 } 2420 2421 return warning_n (&richloc, OPT_Wrestrict, arg_positions.length (), 2422 "passing argument %i to restrict-qualified parameter" 2423 " aliases with argument %Z", 2424 "passing argument %i to restrict-qualified parameter" 2425 " aliases with arguments %Z", 2426 param_pos + 1, arg_positions.address (), 2427 arg_positions.length ()); 2428 } 2429 2430 /* Callback function to determine whether an expression TP or one of its 2431 subexpressions comes from macro expansion. Used to suppress bogus 2432 warnings. */ 2433 2434 static tree 2435 expr_from_macro_expansion_r (tree *tp, int *, void *) 2436 { 2437 if (CAN_HAVE_LOCATION_P (*tp) 2438 && from_macro_expansion_at (EXPR_LOCATION (*tp))) 2439 return integer_zero_node; 2440 2441 return NULL_TREE; 2442 } 2443 2444 /* Possibly warn when an if-else has identical branches. */ 2445 2446 static void 2447 do_warn_duplicated_branches (tree expr) 2448 { 2449 tree thenb = COND_EXPR_THEN (expr); 2450 tree elseb = COND_EXPR_ELSE (expr); 2451 2452 /* Don't bother if any of the branches is missing. */ 2453 if (thenb == NULL_TREE || elseb == NULL_TREE) 2454 return; 2455 2456 /* And don't warn for empty statements. */ 2457 if (TREE_CODE (thenb) == NOP_EXPR 2458 && TREE_TYPE (thenb) == void_type_node 2459 && TREE_OPERAND (thenb, 0) == size_zero_node) 2460 return; 2461 2462 /* ... or empty branches. */ 2463 if (TREE_CODE (thenb) == STATEMENT_LIST 2464 && STATEMENT_LIST_HEAD (thenb) == NULL) 2465 return; 2466 2467 /* Compute the hash of the then branch. */ 2468 inchash::hash hstate0 (0); 2469 inchash::add_expr (thenb, hstate0); 2470 hashval_t h0 = hstate0.end (); 2471 2472 /* Compute the hash of the else branch. */ 2473 inchash::hash hstate1 (0); 2474 inchash::add_expr (elseb, hstate1); 2475 hashval_t h1 = hstate1.end (); 2476 2477 /* Compare the hashes. */ 2478 if (h0 == h1 2479 && operand_equal_p (thenb, elseb, OEP_LEXICOGRAPHIC) 2480 /* Don't warn if any of the branches or their subexpressions comes 2481 from a macro. */ 2482 && !walk_tree_without_duplicates (&thenb, expr_from_macro_expansion_r, 2483 NULL) 2484 && !walk_tree_without_duplicates (&elseb, expr_from_macro_expansion_r, 2485 NULL)) 2486 warning_at (EXPR_LOCATION (expr), OPT_Wduplicated_branches, 2487 "this condition has identical branches"); 2488 } 2489 2490 /* Callback for c_genericize to implement -Wduplicated-branches. */ 2491 2492 tree 2493 do_warn_duplicated_branches_r (tree *tp, int *, void *) 2494 { 2495 if (TREE_CODE (*tp) == COND_EXPR) 2496 do_warn_duplicated_branches (*tp); 2497 return NULL_TREE; 2498 } 2499 2500 /* Implementation of -Wmultistatement-macros. This warning warns about 2501 cases when a macro expands to multiple statements not wrapped in 2502 do {} while (0) or ({ }) and is used as a body of if/else/for/while 2503 conditionals. For example, 2504 2505 #define DOIT x++; y++ 2506 2507 if (c) 2508 DOIT; 2509 2510 will increment y unconditionally. 2511 2512 BODY_LOC is the location of the first token in the body after labels 2513 have been parsed, NEXT_LOC is the location of the next token after the 2514 body of the conditional has been parsed, and GUARD_LOC is the location 2515 of the conditional. */ 2516 2517 void 2518 warn_for_multistatement_macros (location_t body_loc, location_t next_loc, 2519 location_t guard_loc, enum rid keyword) 2520 { 2521 if (!warn_multistatement_macros) 2522 return; 2523 2524 /* Ain't got time to waste. We only care about macros here. */ 2525 if (!from_macro_expansion_at (body_loc) 2526 || !from_macro_expansion_at (next_loc)) 2527 return; 2528 2529 /* Let's skip macros defined in system headers. */ 2530 if (in_system_header_at (body_loc) 2531 || in_system_header_at (next_loc)) 2532 return; 2533 2534 /* Find the actual tokens in the macro definition. BODY_LOC and 2535 NEXT_LOC have to come from the same spelling location, but they 2536 will resolve to different locations in the context of the macro 2537 definition. */ 2538 location_t body_loc_exp 2539 = linemap_resolve_location (line_table, body_loc, 2540 LRK_MACRO_DEFINITION_LOCATION, NULL); 2541 location_t next_loc_exp 2542 = linemap_resolve_location (line_table, next_loc, 2543 LRK_MACRO_DEFINITION_LOCATION, NULL); 2544 location_t guard_loc_exp 2545 = linemap_resolve_location (line_table, guard_loc, 2546 LRK_MACRO_DEFINITION_LOCATION, NULL); 2547 2548 /* These are some funky cases we don't want to warn about. */ 2549 if (body_loc_exp == guard_loc_exp 2550 || next_loc_exp == guard_loc_exp 2551 || body_loc_exp == next_loc_exp) 2552 return; 2553 2554 /* Find the macro maps for the macro expansions. */ 2555 const line_map *body_map = linemap_lookup (line_table, body_loc); 2556 const line_map *next_map = linemap_lookup (line_table, next_loc); 2557 const line_map *guard_map = linemap_lookup (line_table, guard_loc); 2558 2559 /* Now see if the following token (after the body) is coming from the 2560 same macro expansion. If it is, it might be a problem. */ 2561 if (body_map != next_map) 2562 return; 2563 2564 /* The conditional itself must not come from the same expansion, because 2565 we don't want to warn about 2566 #define IF if (x) x++; y++ 2567 and similar. */ 2568 if (guard_map == body_map) 2569 return; 2570 2571 /* Handle the case where NEXT and BODY come from the same expansion while 2572 GUARD doesn't, yet we shouldn't warn. E.g. 2573 2574 #define GUARD if (...) 2575 #define GUARD2 GUARD 2576 2577 and in the definition of another macro: 2578 2579 GUARD2 2580 foo (); 2581 return 1; 2582 */ 2583 while (linemap_macro_expansion_map_p (guard_map)) 2584 { 2585 const line_map_macro *mm = linemap_check_macro (guard_map); 2586 guard_loc_exp = MACRO_MAP_EXPANSION_POINT_LOCATION (mm); 2587 guard_map = linemap_lookup (line_table, guard_loc_exp); 2588 if (guard_map == body_map) 2589 return; 2590 } 2591 2592 if (warning_at (body_loc, OPT_Wmultistatement_macros, 2593 "macro expands to multiple statements")) 2594 inform (guard_loc, "some parts of macro expansion are not guarded by " 2595 "this %qs clause", guard_tinfo_to_string (keyword)); 2596 } 2597