1 /* Language-level data type conversion for GNU C++. 2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 4 Free Software Foundation, Inc. 5 Hacked by Michael Tiemann (tiemann@cygnus.com) 6 7 This file is part of GCC. 8 9 GCC is free software; you can redistribute it and/or modify 10 it under the terms of the GNU General Public License as published by 11 the Free Software Foundation; either version 3, or (at your option) 12 any later version. 13 14 GCC is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License for more details. 18 19 You should have received a copy of the GNU General Public License 20 along with GCC; see the file COPYING3. If not see 21 <http://www.gnu.org/licenses/>. */ 22 23 24 /* This file contains the functions for converting C++ expressions 25 to different data types. The only entry point is `convert'. 26 Every language front end must have a `convert' function 27 but what kind of conversions it does will depend on the language. */ 28 29 #include "config.h" 30 #include "system.h" 31 #include "coretypes.h" 32 #include "tm.h" 33 #include "tree.h" 34 #include "flags.h" 35 #include "cp-tree.h" 36 #include "intl.h" 37 #include "convert.h" 38 #include "toplev.h" 39 #include "decl.h" 40 #include "target.h" 41 42 static tree cp_convert_to_pointer (tree, tree); 43 static tree convert_to_pointer_force (tree, tree); 44 static tree build_type_conversion (tree, tree); 45 static tree build_up_reference (tree, tree, int, tree); 46 static void warn_ref_binding (tree, tree, tree); 47 48 /* Change of width--truncation and extension of integers or reals-- 49 is represented with NOP_EXPR. Proper functioning of many things 50 assumes that no other conversions can be NOP_EXPRs. 51 52 Conversion between integer and pointer is represented with CONVERT_EXPR. 53 Converting integer to real uses FLOAT_EXPR 54 and real to integer uses FIX_TRUNC_EXPR. 55 56 Here is a list of all the functions that assume that widening and 57 narrowing is always done with a NOP_EXPR: 58 In convert.c, convert_to_integer. 59 In c-typeck.c, build_binary_op_nodefault (boolean ops), 60 and c_common_truthvalue_conversion. 61 In expr.c: expand_expr, for operands of a MULT_EXPR. 62 In fold-const.c: fold. 63 In tree.c: get_narrower and get_unwidened. 64 65 C++: in multiple-inheritance, converting between pointers may involve 66 adjusting them by a delta stored within the class definition. */ 67 68 /* Subroutines of `convert'. */ 69 70 /* if converting pointer to pointer 71 if dealing with classes, check for derived->base or vice versa 72 else if dealing with method pointers, delegate 73 else convert blindly 74 else if converting class, pass off to build_type_conversion 75 else try C-style pointer conversion. */ 76 77 static tree 78 cp_convert_to_pointer (tree type, tree expr) 79 { 80 tree intype = TREE_TYPE (expr); 81 enum tree_code form; 82 tree rval; 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 error ("can't convert from incomplete type %qT to %qT", 92 intype, type); 93 return error_mark_node; 94 } 95 96 rval = build_type_conversion (type, expr); 97 if (rval) 98 { 99 if (rval == error_mark_node) 100 error ("conversion of %qE from %qT to %qT is ambiguous", 101 expr, intype, type); 102 return rval; 103 } 104 } 105 106 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */ 107 if (TREE_CODE (type) == POINTER_TYPE 108 && (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE 109 || VOID_TYPE_P (TREE_TYPE (type)))) 110 { 111 if (TYPE_PTRMEMFUNC_P (intype) 112 || TREE_CODE (intype) == METHOD_TYPE) 113 return convert_member_func_to_ptr (type, expr); 114 if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE) 115 return build_nop (type, expr); 116 intype = TREE_TYPE (expr); 117 } 118 119 if (expr == error_mark_node) 120 return error_mark_node; 121 122 form = TREE_CODE (intype); 123 124 if (POINTER_TYPE_P (intype)) 125 { 126 intype = TYPE_MAIN_VARIANT (intype); 127 128 if (TYPE_MAIN_VARIANT (type) != intype 129 && TREE_CODE (type) == POINTER_TYPE 130 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE 131 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type)) 132 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype)) 133 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE) 134 { 135 enum tree_code code = PLUS_EXPR; 136 tree binfo; 137 tree intype_class; 138 tree type_class; 139 bool same_p; 140 141 intype_class = TREE_TYPE (intype); 142 type_class = TREE_TYPE (type); 143 144 same_p = same_type_p (TYPE_MAIN_VARIANT (intype_class), 145 TYPE_MAIN_VARIANT (type_class)); 146 binfo = NULL_TREE; 147 /* Try derived to base conversion. */ 148 if (!same_p) 149 binfo = lookup_base (intype_class, type_class, ba_check, NULL); 150 if (!same_p && !binfo) 151 { 152 /* Try base to derived conversion. */ 153 binfo = lookup_base (type_class, intype_class, ba_check, NULL); 154 code = MINUS_EXPR; 155 } 156 if (binfo == error_mark_node) 157 return error_mark_node; 158 if (binfo || same_p) 159 { 160 if (binfo) 161 expr = build_base_path (code, expr, binfo, 0); 162 /* Add any qualifier conversions. */ 163 return build_nop (type, expr); 164 } 165 } 166 167 if (TYPE_PTRMEMFUNC_P (type)) 168 { 169 error ("cannot convert %qE from type %qT to type %qT", 170 expr, intype, type); 171 return error_mark_node; 172 } 173 174 return build_nop (type, expr); 175 } 176 else if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype)) 177 || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype))) 178 return convert_ptrmem (type, expr, /*allow_inverse_p=*/false, 179 /*c_cast_p=*/false); 180 else if (TYPE_PTRMEMFUNC_P (intype)) 181 { 182 if (!warn_pmf2ptr) 183 { 184 if (TREE_CODE (expr) == PTRMEM_CST) 185 return cp_convert_to_pointer (type, 186 PTRMEM_CST_MEMBER (expr)); 187 else if (TREE_CODE (expr) == OFFSET_REF) 188 { 189 tree object = TREE_OPERAND (expr, 0); 190 return get_member_function_from_ptrfunc (&object, 191 TREE_OPERAND (expr, 1)); 192 } 193 } 194 error ("cannot convert %qE from type %qT to type %qT", 195 expr, intype, type); 196 return error_mark_node; 197 } 198 199 if (integer_zerop (expr)) 200 { 201 if (TYPE_PTRMEMFUNC_P (type)) 202 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0, 203 /*c_cast_p=*/false); 204 205 if (TYPE_PTRMEM_P (type)) 206 { 207 /* A NULL pointer-to-member is represented by -1, not by 208 zero. */ 209 expr = build_int_cst_type (type, -1); 210 } 211 else 212 expr = build_int_cst (type, 0); 213 214 return expr; 215 } 216 else if (TYPE_PTR_TO_MEMBER_P (type) && INTEGRAL_CODE_P (form)) 217 { 218 error ("invalid conversion from %qT to %qT", intype, type); 219 return error_mark_node; 220 } 221 222 if (INTEGRAL_CODE_P (form)) 223 { 224 if (TYPE_PRECISION (intype) == POINTER_SIZE) 225 return build1 (CONVERT_EXPR, type, expr); 226 expr = cp_convert (c_common_type_for_size (POINTER_SIZE, 0), expr); 227 /* Modes may be different but sizes should be the same. There 228 is supposed to be some integral type that is the same width 229 as a pointer. */ 230 gcc_assert (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))) 231 == GET_MODE_SIZE (TYPE_MODE (type))); 232 233 return convert_to_pointer (type, expr); 234 } 235 236 if (type_unknown_p (expr)) 237 return instantiate_type (type, expr, tf_warning_or_error); 238 239 error ("cannot convert %qE from type %qT to type %qT", 240 expr, intype, type); 241 return error_mark_node; 242 } 243 244 /* Like convert, except permit conversions to take place which 245 are not normally allowed due to access restrictions 246 (such as conversion from sub-type to private super-type). */ 247 248 static tree 249 convert_to_pointer_force (tree type, tree expr) 250 { 251 tree intype = TREE_TYPE (expr); 252 enum tree_code form = TREE_CODE (intype); 253 254 if (form == POINTER_TYPE) 255 { 256 intype = TYPE_MAIN_VARIANT (intype); 257 258 if (TYPE_MAIN_VARIANT (type) != intype 259 && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE 260 && MAYBE_CLASS_TYPE_P (TREE_TYPE (type)) 261 && MAYBE_CLASS_TYPE_P (TREE_TYPE (intype)) 262 && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE) 263 { 264 enum tree_code code = PLUS_EXPR; 265 tree binfo; 266 267 binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type), 268 ba_unique, NULL); 269 if (!binfo) 270 { 271 binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype), 272 ba_unique, NULL); 273 code = MINUS_EXPR; 274 } 275 if (binfo == error_mark_node) 276 return error_mark_node; 277 if (binfo) 278 { 279 expr = build_base_path (code, expr, binfo, 0); 280 if (expr == error_mark_node) 281 return error_mark_node; 282 /* Add any qualifier conversions. */ 283 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)), 284 TREE_TYPE (type))) 285 expr = build_nop (type, expr); 286 return expr; 287 } 288 } 289 } 290 291 return cp_convert_to_pointer (type, expr); 292 } 293 294 /* We are passing something to a function which requires a reference. 295 The type we are interested in is in TYPE. The initial 296 value we have to begin with is in ARG. 297 298 FLAGS controls how we manage access checking. 299 DIRECT_BIND in FLAGS controls how any temporaries are generated. 300 If DIRECT_BIND is set, DECL is the reference we're binding to. */ 301 302 static tree 303 build_up_reference (tree type, tree arg, int flags, tree decl) 304 { 305 tree rval; 306 tree argtype = TREE_TYPE (arg); 307 tree target_type = TREE_TYPE (type); 308 309 gcc_assert (TREE_CODE (type) == REFERENCE_TYPE); 310 311 if ((flags & DIRECT_BIND) && ! real_lvalue_p (arg)) 312 { 313 /* Create a new temporary variable. We can't just use a TARGET_EXPR 314 here because it needs to live as long as DECL. */ 315 tree targ = arg; 316 317 arg = make_temporary_var_for_ref_to_temp (decl, TREE_TYPE (arg)); 318 319 /* Process the initializer for the declaration. */ 320 DECL_INITIAL (arg) = targ; 321 cp_finish_decl (arg, targ, /*init_const_expr_p=*/false, NULL_TREE, 322 LOOKUP_ONLYCONVERTING|DIRECT_BIND); 323 } 324 else if (!(flags & DIRECT_BIND) && ! lvalue_p (arg)) 325 return get_target_expr (arg); 326 327 /* If we had a way to wrap this up, and say, if we ever needed its 328 address, transform all occurrences of the register, into a memory 329 reference we could win better. */ 330 rval = cp_build_unary_op (ADDR_EXPR, arg, 1, tf_warning_or_error); 331 if (rval == error_mark_node) 332 return error_mark_node; 333 334 if ((flags & LOOKUP_PROTECT) 335 && TYPE_MAIN_VARIANT (argtype) != TYPE_MAIN_VARIANT (target_type) 336 && MAYBE_CLASS_TYPE_P (argtype) 337 && MAYBE_CLASS_TYPE_P (target_type)) 338 { 339 /* We go through lookup_base for the access control. */ 340 tree binfo = lookup_base (argtype, target_type, ba_check, NULL); 341 if (binfo == error_mark_node) 342 return error_mark_node; 343 if (binfo == NULL_TREE) 344 return error_not_base_type (target_type, argtype); 345 rval = build_base_path (PLUS_EXPR, rval, binfo, 1); 346 } 347 else 348 rval 349 = convert_to_pointer_force (build_pointer_type (target_type), rval); 350 return build_nop (type, rval); 351 } 352 353 /* Subroutine of convert_to_reference. REFTYPE is the target reference type. 354 INTYPE is the original rvalue type and DECL is an optional _DECL node 355 for diagnostics. 356 357 [dcl.init.ref] says that if an rvalue is used to 358 initialize a reference, then the reference must be to a 359 non-volatile const type. */ 360 361 static void 362 warn_ref_binding (tree reftype, tree intype, tree decl) 363 { 364 tree ttl = TREE_TYPE (reftype); 365 366 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl)) 367 { 368 const char *msg; 369 370 if (CP_TYPE_VOLATILE_P (ttl) && decl) 371 msg = G_("initialization of volatile reference type %q#T from " 372 "rvalue of type %qT"); 373 else if (CP_TYPE_VOLATILE_P (ttl)) 374 msg = G_("conversion to volatile reference type %q#T " 375 "from rvalue of type %qT"); 376 else if (decl) 377 msg = G_("initialization of non-const reference type %q#T from " 378 "rvalue of type %qT"); 379 else 380 msg = G_("conversion to non-const reference type %q#T from " 381 "rvalue of type %qT"); 382 383 permerror (input_location, msg, reftype, intype); 384 } 385 } 386 387 /* For C++: Only need to do one-level references, but cannot 388 get tripped up on signed/unsigned differences. 389 390 DECL is either NULL_TREE or the _DECL node for a reference that is being 391 initialized. It can be error_mark_node if we don't know the _DECL but 392 we know it's an initialization. */ 393 394 tree 395 convert_to_reference (tree reftype, tree expr, int convtype, 396 int flags, tree decl) 397 { 398 tree type = TYPE_MAIN_VARIANT (TREE_TYPE (reftype)); 399 tree intype; 400 tree rval = NULL_TREE; 401 tree rval_as_conversion = NULL_TREE; 402 bool can_convert_intype_to_type; 403 404 if (TREE_CODE (type) == FUNCTION_TYPE 405 && TREE_TYPE (expr) == unknown_type_node) 406 expr = instantiate_type (type, expr, 407 (flags & LOOKUP_COMPLAIN) 408 ? tf_warning_or_error : tf_none); 409 410 if (expr == error_mark_node) 411 return error_mark_node; 412 413 intype = TREE_TYPE (expr); 414 415 gcc_assert (TREE_CODE (intype) != REFERENCE_TYPE); 416 gcc_assert (TREE_CODE (reftype) == REFERENCE_TYPE); 417 418 intype = TYPE_MAIN_VARIANT (intype); 419 420 can_convert_intype_to_type = can_convert (type, intype); 421 if (!can_convert_intype_to_type 422 && (convtype & CONV_IMPLICIT) && MAYBE_CLASS_TYPE_P (intype) 423 && ! (flags & LOOKUP_NO_CONVERSION)) 424 { 425 /* Look for a user-defined conversion to lvalue that we can use. */ 426 427 rval_as_conversion 428 = build_type_conversion (reftype, expr); 429 430 if (rval_as_conversion && rval_as_conversion != error_mark_node 431 && real_lvalue_p (rval_as_conversion)) 432 { 433 expr = rval_as_conversion; 434 rval_as_conversion = NULL_TREE; 435 intype = type; 436 can_convert_intype_to_type = 1; 437 } 438 } 439 440 if (((convtype & CONV_STATIC) && can_convert (intype, type)) 441 || ((convtype & CONV_IMPLICIT) && can_convert_intype_to_type)) 442 { 443 if (flags & LOOKUP_COMPLAIN) 444 { 445 tree ttl = TREE_TYPE (reftype); 446 tree ttr = lvalue_type (expr); 447 448 if (! real_lvalue_p (expr)) 449 warn_ref_binding (reftype, intype, decl); 450 451 if (! (convtype & CONV_CONST) 452 && !at_least_as_qualified_p (ttl, ttr)) 453 permerror (input_location, "conversion from %qT to %qT discards qualifiers", 454 ttr, reftype); 455 } 456 457 return build_up_reference (reftype, expr, flags, decl); 458 } 459 else if ((convtype & CONV_REINTERPRET) && lvalue_p (expr)) 460 { 461 /* When casting an lvalue to a reference type, just convert into 462 a pointer to the new type and deference it. This is allowed 463 by San Diego WP section 5.2.9 paragraph 12, though perhaps it 464 should be done directly (jason). (int &)ri ---> *(int*)&ri */ 465 466 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they 467 meant. */ 468 if (TREE_CODE (intype) == POINTER_TYPE 469 && (comptypes (TREE_TYPE (intype), type, 470 COMPARE_BASE | COMPARE_DERIVED))) 471 warning (0, "casting %qT to %qT does not dereference pointer", 472 intype, reftype); 473 474 rval = cp_build_unary_op (ADDR_EXPR, expr, 0, tf_warning_or_error); 475 if (rval != error_mark_node) 476 rval = convert_force (build_pointer_type (TREE_TYPE (reftype)), 477 rval, 0); 478 if (rval != error_mark_node) 479 rval = build1 (NOP_EXPR, reftype, rval); 480 } 481 else 482 { 483 rval = convert_for_initialization (NULL_TREE, type, expr, flags, 484 "converting", 0, 0, 485 tf_warning_or_error); 486 if (rval == NULL_TREE || rval == error_mark_node) 487 return rval; 488 warn_ref_binding (reftype, intype, decl); 489 rval = build_up_reference (reftype, rval, flags, decl); 490 } 491 492 if (rval) 493 { 494 /* If we found a way to convert earlier, then use it. */ 495 return rval; 496 } 497 498 if (flags & LOOKUP_COMPLAIN) 499 error ("cannot convert type %qT to type %qT", intype, reftype); 500 501 return error_mark_node; 502 } 503 504 /* We are using a reference VAL for its value. Bash that reference all the 505 way down to its lowest form. */ 506 507 tree 508 convert_from_reference (tree val) 509 { 510 if (TREE_TYPE (val) 511 && TREE_CODE (TREE_TYPE (val)) == REFERENCE_TYPE) 512 { 513 tree t = TREE_TYPE (TREE_TYPE (val)); 514 tree ref = build1 (INDIRECT_REF, t, val); 515 516 /* We *must* set TREE_READONLY when dereferencing a pointer to const, 517 so that we get the proper error message if the result is used 518 to assign to. Also, &* is supposed to be a no-op. */ 519 TREE_READONLY (ref) = CP_TYPE_CONST_P (t); 520 TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t); 521 TREE_SIDE_EFFECTS (ref) 522 = (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (val)); 523 REFERENCE_REF_P (ref) = 1; 524 val = ref; 525 } 526 527 return val; 528 } 529 530 /* Really perform an lvalue-to-rvalue conversion, including copying an 531 argument of class type into a temporary. */ 532 533 tree 534 force_rvalue (tree expr) 535 { 536 if (MAYBE_CLASS_TYPE_P (TREE_TYPE (expr)) && TREE_CODE (expr) != TARGET_EXPR) 537 expr = ocp_convert (TREE_TYPE (expr), expr, 538 CONV_IMPLICIT|CONV_FORCE_TEMP, LOOKUP_NORMAL); 539 else 540 expr = decay_conversion (expr); 541 542 return expr; 543 } 544 545 546 /* Fold away simple conversions, but make sure the result is an rvalue. */ 547 548 tree 549 cp_fold_convert (tree type, tree expr) 550 { 551 return rvalue (fold_convert (type, expr)); 552 } 553 554 /* C++ conversions, preference to static cast conversions. */ 555 556 tree 557 cp_convert (tree type, tree expr) 558 { 559 return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL); 560 } 561 562 /* C++ equivalent of convert_and_check but using cp_convert as the 563 conversion function. 564 565 Convert EXPR to TYPE, warning about conversion problems with constants. 566 Invoke this function on every expression that is converted implicitly, 567 i.e. because of language rules and not because of an explicit cast. */ 568 569 tree 570 cp_convert_and_check (tree type, tree expr) 571 { 572 tree result; 573 574 if (TREE_TYPE (expr) == type) 575 return expr; 576 577 result = cp_convert (type, expr); 578 579 if (c_inhibit_evaluation_warnings == 0 580 && !TREE_OVERFLOW_P (expr) 581 && result != error_mark_node) 582 warnings_for_convert_and_check (type, expr, result); 583 584 return result; 585 } 586 587 /* Conversion... 588 589 FLAGS indicates how we should behave. */ 590 591 tree 592 ocp_convert (tree type, tree expr, int convtype, int flags) 593 { 594 tree e = expr; 595 enum tree_code code = TREE_CODE (type); 596 const char *invalid_conv_diag; 597 tree e1; 598 599 if (error_operand_p (e) || type == error_mark_node) 600 return error_mark_node; 601 602 complete_type (type); 603 complete_type (TREE_TYPE (expr)); 604 605 if ((invalid_conv_diag 606 = targetm.invalid_conversion (TREE_TYPE (expr), type))) 607 { 608 error (invalid_conv_diag); 609 return error_mark_node; 610 } 611 612 e = integral_constant_value (e); 613 614 if (MAYBE_CLASS_TYPE_P (type) && (convtype & CONV_FORCE_TEMP)) 615 /* We need a new temporary; don't take this shortcut. */; 616 else if (same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (e))) 617 { 618 if (same_type_p (type, TREE_TYPE (e))) 619 /* The call to fold will not always remove the NOP_EXPR as 620 might be expected, since if one of the types is a typedef; 621 the comparison in fold is just equality of pointers, not a 622 call to comptypes. We don't call fold in this case because 623 that can result in infinite recursion; fold will call 624 convert, which will call ocp_convert, etc. */ 625 return e; 626 /* For complex data types, we need to perform componentwise 627 conversion. */ 628 else if (TREE_CODE (type) == COMPLEX_TYPE) 629 return fold_if_not_in_template (convert_to_complex (type, e)); 630 else if (TREE_CODE (e) == TARGET_EXPR) 631 { 632 /* Don't build a NOP_EXPR of class type. Instead, change the 633 type of the temporary. */ 634 TREE_TYPE (e) = TREE_TYPE (TARGET_EXPR_SLOT (e)) = type; 635 return e; 636 } 637 else 638 { 639 /* We shouldn't be treating objects of ADDRESSABLE type as 640 rvalues. */ 641 gcc_assert (!TREE_ADDRESSABLE (type)); 642 return fold_if_not_in_template (build_nop (type, e)); 643 } 644 } 645 646 e1 = targetm.convert_to_type (type, e); 647 if (e1) 648 return e1; 649 650 if (code == VOID_TYPE && (convtype & CONV_STATIC)) 651 { 652 e = convert_to_void (e, /*implicit=*/NULL, tf_warning_or_error); 653 return e; 654 } 655 656 if (INTEGRAL_CODE_P (code)) 657 { 658 tree intype = TREE_TYPE (e); 659 660 if (TREE_CODE (type) == ENUMERAL_TYPE) 661 { 662 /* enum = enum, enum = int, enum = float, (enum)pointer are all 663 errors. */ 664 if (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype) 665 || TREE_CODE (intype) == REAL_TYPE) 666 && ! (convtype & CONV_STATIC)) 667 || TREE_CODE (intype) == POINTER_TYPE) 668 { 669 if (flags & LOOKUP_COMPLAIN) 670 permerror (input_location, "conversion from %q#T to %q#T", intype, type); 671 672 if (!flag_permissive) 673 return error_mark_node; 674 } 675 676 /* [expr.static.cast] 677 678 8. A value of integral or enumeration type can be explicitly 679 converted to an enumeration type. The value is unchanged if 680 the original value is within the range of the enumeration 681 values. Otherwise, the resulting enumeration value is 682 unspecified. */ 683 if (TREE_CODE (expr) == INTEGER_CST && !int_fits_type_p (expr, type)) 684 warning (OPT_Wconversion, 685 "the result of the conversion is unspecified because " 686 "%qE is outside the range of type %qT", 687 expr, type); 688 } 689 if (MAYBE_CLASS_TYPE_P (intype)) 690 { 691 tree rval; 692 rval = build_type_conversion (type, e); 693 if (rval) 694 return rval; 695 if (flags & LOOKUP_COMPLAIN) 696 error ("%q#T used where a %qT was expected", intype, type); 697 return error_mark_node; 698 } 699 if (code == BOOLEAN_TYPE) 700 return cp_truthvalue_conversion (e); 701 702 return fold_if_not_in_template (convert_to_integer (type, e)); 703 } 704 if (POINTER_TYPE_P (type) || TYPE_PTR_TO_MEMBER_P (type)) 705 return fold_if_not_in_template (cp_convert_to_pointer (type, e)); 706 if (code == VECTOR_TYPE) 707 { 708 tree in_vtype = TREE_TYPE (e); 709 if (MAYBE_CLASS_TYPE_P (in_vtype)) 710 { 711 tree ret_val; 712 ret_val = build_type_conversion (type, e); 713 if (ret_val) 714 return ret_val; 715 if (flags & LOOKUP_COMPLAIN) 716 error ("%q#T used where a %qT was expected", in_vtype, type); 717 return error_mark_node; 718 } 719 return fold_if_not_in_template (convert_to_vector (type, e)); 720 } 721 if (code == REAL_TYPE || code == COMPLEX_TYPE) 722 { 723 if (MAYBE_CLASS_TYPE_P (TREE_TYPE (e))) 724 { 725 tree rval; 726 rval = build_type_conversion (type, e); 727 if (rval) 728 return rval; 729 else 730 if (flags & LOOKUP_COMPLAIN) 731 error ("%q#T used where a floating point value was expected", 732 TREE_TYPE (e)); 733 } 734 if (code == REAL_TYPE) 735 return fold_if_not_in_template (convert_to_real (type, e)); 736 else if (code == COMPLEX_TYPE) 737 return fold_if_not_in_template (convert_to_complex (type, e)); 738 } 739 740 /* New C++ semantics: since assignment is now based on 741 memberwise copying, if the rhs type is derived from the 742 lhs type, then we may still do a conversion. */ 743 if (RECORD_OR_UNION_CODE_P (code)) 744 { 745 tree dtype = TREE_TYPE (e); 746 tree ctor = NULL_TREE; 747 748 dtype = TYPE_MAIN_VARIANT (dtype); 749 750 /* Conversion between aggregate types. New C++ semantics allow 751 objects of derived type to be cast to objects of base type. 752 Old semantics only allowed this between pointers. 753 754 There may be some ambiguity between using a constructor 755 vs. using a type conversion operator when both apply. */ 756 757 ctor = e; 758 759 if (abstract_virtuals_error (NULL_TREE, type)) 760 return error_mark_node; 761 762 if (BRACE_ENCLOSED_INITIALIZER_P (ctor)) 763 ctor = perform_implicit_conversion (type, ctor, tf_warning_or_error); 764 else if ((flags & LOOKUP_ONLYCONVERTING) 765 && ! (CLASS_TYPE_P (dtype) && DERIVED_FROM_P (type, dtype))) 766 /* For copy-initialization, first we create a temp of the proper type 767 with a user-defined conversion sequence, then we direct-initialize 768 the target with the temp (see [dcl.init]). */ 769 ctor = build_user_type_conversion (type, ctor, flags); 770 else 771 { 772 VEC(tree,gc) *ctor_vec = make_tree_vector_single (ctor); 773 ctor = build_special_member_call (NULL_TREE, 774 complete_ctor_identifier, 775 &ctor_vec, 776 type, flags, 777 tf_warning_or_error); 778 release_tree_vector (ctor_vec); 779 } 780 if (ctor) 781 return build_cplus_new (type, ctor); 782 } 783 784 if (flags & LOOKUP_COMPLAIN) 785 { 786 /* If the conversion failed and expr was an invalid use of pointer to 787 member function, try to report a meaningful error. */ 788 if (invalid_nonstatic_memfn_p (expr, tf_warning_or_error)) 789 /* We displayed the error message. */; 790 else 791 error ("conversion from %qT to non-scalar type %qT requested", 792 TREE_TYPE (expr), type); 793 } 794 return error_mark_node; 795 } 796 797 /* When an expression is used in a void context, its value is discarded and 798 no lvalue-rvalue and similar conversions happen [expr.static.cast/4, 799 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type 800 in a void context. The C++ standard does not define what an `access' to an 801 object is, but there is reason to believe that it is the lvalue to rvalue 802 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it 803 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8 804 indicates that volatile semantics should be the same between C and C++ 805 where ever possible. C leaves it implementation defined as to what 806 constitutes an access to a volatile. So, we interpret `*vp' as a read of 807 the volatile object `vp' points to, unless that is an incomplete type. For 808 volatile references we do not do this interpretation, because that would 809 make it impossible to ignore the reference return value from functions. We 810 issue warnings in the confusing cases. 811 812 IMPLICIT is non-NULL iff an expression is being implicitly converted; it 813 is NULL when the user is explicitly converting an expression to void via 814 a cast. When non-NULL, IMPLICIT is a string indicating the context of 815 the implicit conversion. */ 816 817 tree 818 convert_to_void (tree expr, const char *implicit, tsubst_flags_t complain) 819 { 820 if (expr == error_mark_node 821 || TREE_TYPE (expr) == error_mark_node) 822 return error_mark_node; 823 if (!TREE_TYPE (expr)) 824 return expr; 825 if (invalid_nonstatic_memfn_p (expr, complain)) 826 return error_mark_node; 827 if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR) 828 { 829 if (complain & tf_error) 830 error ("pseudo-destructor is not called"); 831 return error_mark_node; 832 } 833 if (VOID_TYPE_P (TREE_TYPE (expr))) 834 return expr; 835 switch (TREE_CODE (expr)) 836 { 837 case COND_EXPR: 838 { 839 /* The two parts of a cond expr might be separate lvalues. */ 840 tree op1 = TREE_OPERAND (expr,1); 841 tree op2 = TREE_OPERAND (expr,2); 842 bool side_effects = TREE_SIDE_EFFECTS (op1) || TREE_SIDE_EFFECTS (op2); 843 tree new_op1 = convert_to_void 844 (op1, (implicit && !side_effects 845 ? "second operand of conditional" : NULL), complain); 846 tree new_op2 = convert_to_void 847 (op2, (implicit && !side_effects 848 ? "third operand of conditional" : NULL), complain); 849 850 expr = build3 (COND_EXPR, TREE_TYPE (new_op1), 851 TREE_OPERAND (expr, 0), new_op1, new_op2); 852 break; 853 } 854 855 case COMPOUND_EXPR: 856 { 857 /* The second part of a compound expr contains the value. */ 858 tree op1 = TREE_OPERAND (expr,1); 859 tree new_op1 = convert_to_void 860 (op1, (implicit && !TREE_NO_WARNING (expr) 861 ? "right-hand operand of comma" : NULL), complain); 862 863 if (new_op1 != op1) 864 { 865 tree t = build2 (COMPOUND_EXPR, TREE_TYPE (new_op1), 866 TREE_OPERAND (expr, 0), new_op1); 867 expr = t; 868 } 869 870 break; 871 } 872 873 case NON_LVALUE_EXPR: 874 case NOP_EXPR: 875 /* These have already decayed to rvalue. */ 876 break; 877 878 case CALL_EXPR: /* We have a special meaning for volatile void fn(). */ 879 break; 880 881 case INDIRECT_REF: 882 { 883 tree type = TREE_TYPE (expr); 884 int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) 885 == REFERENCE_TYPE; 886 int is_volatile = TYPE_VOLATILE (type); 887 int is_complete = COMPLETE_TYPE_P (complete_type (type)); 888 889 /* Can't load the value if we don't know the type. */ 890 if (is_volatile && !is_complete) 891 { 892 if (complain & tf_warning) 893 warning (0, "object of incomplete type %qT will not be accessed in %s", 894 type, implicit ? implicit : "void context"); 895 } 896 /* Don't load the value if this is an implicit dereference, or if 897 the type needs to be handled by ctors/dtors. */ 898 else if (is_volatile && (is_reference || TREE_ADDRESSABLE (type))) 899 { 900 if (complain & tf_warning) 901 warning (0, "object of type %qT will not be accessed in %s", 902 TREE_TYPE (TREE_OPERAND (expr, 0)), 903 implicit ? implicit : "void context"); 904 } 905 if (is_reference || !is_volatile || !is_complete || TREE_ADDRESSABLE (type)) 906 { 907 /* Emit a warning (if enabled) when the "effect-less" INDIRECT_REF 908 operation is stripped off. Note that we don't warn about 909 - an expression with TREE_NO_WARNING set. (For an example of 910 such expressions, see build_over_call in call.c.) 911 - automatic dereferencing of references, since the user cannot 912 control it. (See also warn_if_unused_value() in stmt.c.) */ 913 if (warn_unused_value 914 && implicit 915 && (complain & tf_warning) 916 && !TREE_NO_WARNING (expr) 917 && !is_reference) 918 warning (OPT_Wunused_value, "value computed is not used"); 919 expr = TREE_OPERAND (expr, 0); 920 } 921 922 break; 923 } 924 925 case VAR_DECL: 926 { 927 /* External variables might be incomplete. */ 928 tree type = TREE_TYPE (expr); 929 int is_complete = COMPLETE_TYPE_P (complete_type (type)); 930 931 if (TYPE_VOLATILE (type) && !is_complete && (complain & tf_warning)) 932 warning (0, "object %qE of incomplete type %qT will not be accessed in %s", 933 expr, type, implicit ? implicit : "void context"); 934 break; 935 } 936 937 case TARGET_EXPR: 938 /* Don't bother with the temporary object returned from a function if 939 we don't use it and don't need to destroy it. We'll still 940 allocate space for it in expand_call or declare_return_variable, 941 but we don't need to track it through all the tree phases. */ 942 if (TARGET_EXPR_IMPLICIT_P (expr) 943 && TYPE_HAS_TRIVIAL_DESTRUCTOR (TREE_TYPE (expr))) 944 { 945 tree init = TARGET_EXPR_INITIAL (expr); 946 if (TREE_CODE (init) == AGGR_INIT_EXPR 947 && !AGGR_INIT_VIA_CTOR_P (init)) 948 { 949 tree fn = AGGR_INIT_EXPR_FN (init); 950 expr = build_call_array_loc (input_location, 951 TREE_TYPE (TREE_TYPE (TREE_TYPE (fn))), 952 fn, 953 aggr_init_expr_nargs (init), 954 AGGR_INIT_EXPR_ARGP (init)); 955 } 956 } 957 break; 958 959 default:; 960 } 961 expr = resolve_nondeduced_context (expr); 962 { 963 tree probe = expr; 964 965 if (TREE_CODE (probe) == ADDR_EXPR) 966 probe = TREE_OPERAND (expr, 0); 967 if (type_unknown_p (probe)) 968 { 969 /* [over.over] enumerates the places where we can take the address 970 of an overloaded function, and this is not one of them. */ 971 if (complain & tf_error) 972 error ("%s cannot resolve address of overloaded function", 973 implicit ? implicit : "void cast"); 974 else 975 return error_mark_node; 976 expr = void_zero_node; 977 } 978 else if (implicit && probe == expr && is_overloaded_fn (probe)) 979 { 980 /* Only warn when there is no &. */ 981 if (complain & tf_warning) 982 warning (OPT_Waddress, "%s is a reference, not call, to function %qE", 983 implicit, expr); 984 if (TREE_CODE (expr) == COMPONENT_REF) 985 expr = TREE_OPERAND (expr, 0); 986 } 987 } 988 989 if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr))) 990 { 991 if (implicit 992 && warn_unused_value 993 && !TREE_NO_WARNING (expr) 994 && !processing_template_decl) 995 { 996 /* The middle end does not warn about expressions that have 997 been explicitly cast to void, so we must do so here. */ 998 if (!TREE_SIDE_EFFECTS (expr)) { 999 if (complain & tf_warning) 1000 warning (OPT_Wunused_value, "%s has no effect", implicit); 1001 } 1002 else 1003 { 1004 tree e; 1005 enum tree_code code; 1006 enum tree_code_class tclass; 1007 1008 e = expr; 1009 /* We might like to warn about (say) "(int) f()", as the 1010 cast has no effect, but the compiler itself will 1011 generate implicit conversions under some 1012 circumstances. (For example a block copy will be 1013 turned into a call to "__builtin_memcpy", with a 1014 conversion of the return value to an appropriate 1015 type.) So, to avoid false positives, we strip 1016 conversions. Do not use STRIP_NOPs because it will 1017 not strip conversions to "void", as that is not a 1018 mode-preserving conversion. */ 1019 while (TREE_CODE (e) == NOP_EXPR) 1020 e = TREE_OPERAND (e, 0); 1021 1022 code = TREE_CODE (e); 1023 tclass = TREE_CODE_CLASS (code); 1024 if ((tclass == tcc_comparison 1025 || tclass == tcc_unary 1026 || (tclass == tcc_binary 1027 && !(code == MODIFY_EXPR 1028 || code == INIT_EXPR 1029 || code == PREDECREMENT_EXPR 1030 || code == PREINCREMENT_EXPR 1031 || code == POSTDECREMENT_EXPR 1032 || code == POSTINCREMENT_EXPR))) 1033 && (complain & tf_warning)) 1034 warning (OPT_Wunused_value, "value computed is not used"); 1035 } 1036 } 1037 expr = build1 (CONVERT_EXPR, void_type_node, expr); 1038 } 1039 if (! TREE_SIDE_EFFECTS (expr)) 1040 expr = void_zero_node; 1041 return expr; 1042 } 1043 1044 /* Create an expression whose value is that of EXPR, 1045 converted to type TYPE. The TREE_TYPE of the value 1046 is always TYPE. This function implements all reasonable 1047 conversions; callers should filter out those that are 1048 not permitted by the language being compiled. 1049 1050 Most of this routine is from build_reinterpret_cast. 1051 1052 The back end cannot call cp_convert (what was convert) because 1053 conversions to/from basetypes may involve memory references 1054 (vbases) and adding or subtracting small values (multiple 1055 inheritance), but it calls convert from the constant folding code 1056 on subtrees of already built trees after it has ripped them apart. 1057 1058 Also, if we ever support range variables, we'll probably also have to 1059 do a little bit more work. */ 1060 1061 tree 1062 convert (tree type, tree expr) 1063 { 1064 tree intype; 1065 1066 if (type == error_mark_node || expr == error_mark_node) 1067 return error_mark_node; 1068 1069 intype = TREE_TYPE (expr); 1070 1071 if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype)) 1072 return fold_if_not_in_template (build_nop (type, expr)); 1073 1074 return ocp_convert (type, expr, CONV_OLD_CONVERT, 1075 LOOKUP_NORMAL|LOOKUP_NO_CONVERSION); 1076 } 1077 1078 /* Like cp_convert, except permit conversions to take place which 1079 are not normally allowed due to access restrictions 1080 (such as conversion from sub-type to private super-type). */ 1081 1082 tree 1083 convert_force (tree type, tree expr, int convtype) 1084 { 1085 tree e = expr; 1086 enum tree_code code = TREE_CODE (type); 1087 1088 if (code == REFERENCE_TYPE) 1089 return (fold_if_not_in_template 1090 (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN, 1091 NULL_TREE))); 1092 1093 if (code == POINTER_TYPE) 1094 return fold_if_not_in_template (convert_to_pointer_force (type, e)); 1095 1096 /* From typeck.c convert_for_assignment */ 1097 if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR 1098 && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE 1099 && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE) 1100 || integer_zerop (e) 1101 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e))) 1102 && TYPE_PTRMEMFUNC_P (type)) 1103 /* compatible pointer to member functions. */ 1104 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1, 1105 /*c_cast_p=*/1); 1106 1107 return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL); 1108 } 1109 1110 /* Convert an aggregate EXPR to type XTYPE. If a conversion 1111 exists, return the attempted conversion. This may 1112 return ERROR_MARK_NODE if the conversion is not 1113 allowed (references private members, etc). 1114 If no conversion exists, NULL_TREE is returned. 1115 1116 FIXME: Ambiguity checking is wrong. Should choose one by the implicit 1117 object parameter, or by the second standard conversion sequence if 1118 that doesn't do it. This will probably wait for an overloading rewrite. 1119 (jason 8/9/95) */ 1120 1121 static tree 1122 build_type_conversion (tree xtype, tree expr) 1123 { 1124 /* C++: check to see if we can convert this aggregate type 1125 into the required type. */ 1126 return build_user_type_conversion (xtype, expr, LOOKUP_NORMAL); 1127 } 1128 1129 /* Convert the given EXPR to one of a group of types suitable for use in an 1130 expression. DESIRES is a combination of various WANT_* flags (q.v.) 1131 which indicates which types are suitable. If COMPLAIN is true, complain 1132 about ambiguity; otherwise, the caller will deal with it. */ 1133 1134 tree 1135 build_expr_type_conversion (int desires, tree expr, bool complain) 1136 { 1137 tree basetype = TREE_TYPE (expr); 1138 tree conv = NULL_TREE; 1139 tree winner = NULL_TREE; 1140 1141 if (expr == null_node 1142 && (desires & WANT_INT) 1143 && !(desires & WANT_NULL)) 1144 warning_at (input_location, OPT_Wconversion_null, 1145 "converting NULL to non-pointer type"); 1146 1147 basetype = TREE_TYPE (expr); 1148 1149 if (basetype == error_mark_node) 1150 return error_mark_node; 1151 1152 if (! MAYBE_CLASS_TYPE_P (basetype)) 1153 switch (TREE_CODE (basetype)) 1154 { 1155 case INTEGER_TYPE: 1156 if ((desires & WANT_NULL) && null_ptr_cst_p (expr)) 1157 return expr; 1158 /* else fall through... */ 1159 1160 case BOOLEAN_TYPE: 1161 return (desires & WANT_INT) ? expr : NULL_TREE; 1162 case ENUMERAL_TYPE: 1163 return (desires & WANT_ENUM) ? expr : NULL_TREE; 1164 case REAL_TYPE: 1165 return (desires & WANT_FLOAT) ? expr : NULL_TREE; 1166 case POINTER_TYPE: 1167 return (desires & WANT_POINTER) ? expr : NULL_TREE; 1168 1169 case FUNCTION_TYPE: 1170 case ARRAY_TYPE: 1171 return (desires & WANT_POINTER) ? decay_conversion (expr) 1172 : NULL_TREE; 1173 1174 case COMPLEX_TYPE: 1175 case VECTOR_TYPE: 1176 if ((desires & WANT_VECTOR_OR_COMPLEX) == 0) 1177 return NULL_TREE; 1178 switch (TREE_CODE (TREE_TYPE (basetype))) 1179 { 1180 case INTEGER_TYPE: 1181 case BOOLEAN_TYPE: 1182 return (desires & WANT_INT) ? expr : NULL_TREE; 1183 case ENUMERAL_TYPE: 1184 return (desires & WANT_ENUM) ? expr : NULL_TREE; 1185 case REAL_TYPE: 1186 return (desires & WANT_FLOAT) ? expr : NULL_TREE; 1187 default: 1188 return NULL_TREE; 1189 } 1190 1191 default: 1192 return NULL_TREE; 1193 } 1194 1195 /* The code for conversions from class type is currently only used for 1196 delete expressions. Other expressions are handled by build_new_op. */ 1197 if (!complete_type_or_else (basetype, expr)) 1198 return error_mark_node; 1199 if (!TYPE_HAS_CONVERSION (basetype)) 1200 return NULL_TREE; 1201 1202 for (conv = lookup_conversions (basetype); conv; conv = TREE_CHAIN (conv)) 1203 { 1204 int win = 0; 1205 tree candidate; 1206 tree cand = TREE_VALUE (conv); 1207 cand = OVL_CURRENT (cand); 1208 1209 if (winner && winner == cand) 1210 continue; 1211 1212 if (DECL_NONCONVERTING_P (cand)) 1213 continue; 1214 1215 candidate = non_reference (TREE_TYPE (TREE_TYPE (cand))); 1216 1217 switch (TREE_CODE (candidate)) 1218 { 1219 case BOOLEAN_TYPE: 1220 case INTEGER_TYPE: 1221 win = (desires & WANT_INT); break; 1222 case ENUMERAL_TYPE: 1223 win = (desires & WANT_ENUM); break; 1224 case REAL_TYPE: 1225 win = (desires & WANT_FLOAT); break; 1226 case POINTER_TYPE: 1227 win = (desires & WANT_POINTER); break; 1228 1229 case COMPLEX_TYPE: 1230 case VECTOR_TYPE: 1231 if ((desires & WANT_VECTOR_OR_COMPLEX) == 0) 1232 break; 1233 switch (TREE_CODE (TREE_TYPE (candidate))) 1234 { 1235 case BOOLEAN_TYPE: 1236 case INTEGER_TYPE: 1237 win = (desires & WANT_INT); break; 1238 case ENUMERAL_TYPE: 1239 win = (desires & WANT_ENUM); break; 1240 case REAL_TYPE: 1241 win = (desires & WANT_FLOAT); break; 1242 default: 1243 break; 1244 } 1245 break; 1246 1247 default: 1248 break; 1249 } 1250 1251 if (win) 1252 { 1253 if (winner) 1254 { 1255 if (complain) 1256 { 1257 error ("ambiguous default type conversion from %qT", 1258 basetype); 1259 error (" candidate conversions include %qD and %qD", 1260 winner, cand); 1261 } 1262 return error_mark_node; 1263 } 1264 else 1265 winner = cand; 1266 } 1267 } 1268 1269 if (winner) 1270 { 1271 tree type = non_reference (TREE_TYPE (TREE_TYPE (winner))); 1272 return build_user_type_conversion (type, expr, LOOKUP_NORMAL); 1273 } 1274 1275 return NULL_TREE; 1276 } 1277 1278 /* Implements integral promotion (4.1) and float->double promotion. */ 1279 1280 tree 1281 type_promotes_to (tree type) 1282 { 1283 tree promoted_type; 1284 1285 if (type == error_mark_node) 1286 return error_mark_node; 1287 1288 type = TYPE_MAIN_VARIANT (type); 1289 1290 /* Check for promotions of target-defined types first. */ 1291 promoted_type = targetm.promoted_type (type); 1292 if (promoted_type) 1293 return promoted_type; 1294 1295 /* bool always promotes to int (not unsigned), even if it's the same 1296 size. */ 1297 if (TREE_CODE (type) == BOOLEAN_TYPE) 1298 type = integer_type_node; 1299 1300 /* Normally convert enums to int, but convert wide enums to something 1301 wider. */ 1302 else if (TREE_CODE (type) == ENUMERAL_TYPE 1303 || type == char16_type_node 1304 || type == char32_type_node 1305 || type == wchar_type_node) 1306 { 1307 int precision = MAX (TYPE_PRECISION (type), 1308 TYPE_PRECISION (integer_type_node)); 1309 tree totype = c_common_type_for_size (precision, 0); 1310 if (TYPE_UNSIGNED (type) 1311 && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype)) 1312 type = c_common_type_for_size (precision, 1); 1313 else 1314 type = totype; 1315 } 1316 else if (c_promoting_integer_type_p (type)) 1317 { 1318 /* Retain unsignedness if really not getting bigger. */ 1319 if (TYPE_UNSIGNED (type) 1320 && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node)) 1321 type = unsigned_type_node; 1322 else 1323 type = integer_type_node; 1324 } 1325 else if (type == float_type_node) 1326 type = double_type_node; 1327 1328 return type; 1329 } 1330 1331 /* The routines below this point are carefully written to conform to 1332 the standard. They use the same terminology, and follow the rules 1333 closely. Although they are used only in pt.c at the moment, they 1334 should presumably be used everywhere in the future. */ 1335 1336 /* Attempt to perform qualification conversions on EXPR to convert it 1337 to TYPE. Return the resulting expression, or error_mark_node if 1338 the conversion was impossible. */ 1339 1340 tree 1341 perform_qualification_conversions (tree type, tree expr) 1342 { 1343 tree expr_type; 1344 1345 expr_type = TREE_TYPE (expr); 1346 1347 if (same_type_p (type, expr_type)) 1348 return expr; 1349 else if (TYPE_PTR_P (type) && TYPE_PTR_P (expr_type) 1350 && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (expr_type))) 1351 return build_nop (type, expr); 1352 else if (TYPE_PTR_TO_MEMBER_P (type) 1353 && TYPE_PTR_TO_MEMBER_P (expr_type) 1354 && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type), 1355 TYPE_PTRMEM_CLASS_TYPE (expr_type)) 1356 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type), 1357 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type))) 1358 return build_nop (type, expr); 1359 else 1360 return error_mark_node; 1361 } 1362