ParseTentative.cpp revision f5c209d23b20ada4a9b6235db50317239cbf6ae1
1//===--- ParseTentative.cpp - Ambiguity Resolution Parsing ----------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the tentative parsing portions of the Parser 11// interfaces, for ambiguity resolution. 12// 13//===----------------------------------------------------------------------===// 14 15#include "clang/Parse/Parser.h" 16#include "clang/Parse/ParseDiagnostic.h" 17using namespace clang; 18 19/// isCXXDeclarationStatement - C++-specialized function that disambiguates 20/// between a declaration or an expression statement, when parsing function 21/// bodies. Returns true for declaration, false for expression. 22/// 23/// declaration-statement: 24/// block-declaration 25/// 26/// block-declaration: 27/// simple-declaration 28/// asm-definition 29/// namespace-alias-definition 30/// using-declaration 31/// using-directive 32/// [C++0x] static_assert-declaration 33/// 34/// asm-definition: 35/// 'asm' '(' string-literal ')' ';' 36/// 37/// namespace-alias-definition: 38/// 'namespace' identifier = qualified-namespace-specifier ';' 39/// 40/// using-declaration: 41/// 'using' typename[opt] '::'[opt] nested-name-specifier 42/// unqualified-id ';' 43/// 'using' '::' unqualified-id ; 44/// 45/// using-directive: 46/// 'using' 'namespace' '::'[opt] nested-name-specifier[opt] 47/// namespace-name ';' 48/// 49bool Parser::isCXXDeclarationStatement() { 50 switch (Tok.getKind()) { 51 // asm-definition 52 case tok::kw_asm: 53 // namespace-alias-definition 54 case tok::kw_namespace: 55 // using-declaration 56 // using-directive 57 case tok::kw_using: 58 return true; 59 case tok::kw_static_assert: 60 // static_assert-declaration 61 return true; 62 default: 63 // simple-declaration 64 return isCXXSimpleDeclaration(); 65 } 66} 67 68/// isCXXSimpleDeclaration - C++-specialized function that disambiguates 69/// between a simple-declaration or an expression-statement. 70/// If during the disambiguation process a parsing error is encountered, 71/// the function returns true to let the declaration parsing code handle it. 72/// Returns false if the statement is disambiguated as expression. 73/// 74/// simple-declaration: 75/// decl-specifier-seq init-declarator-list[opt] ';' 76/// 77bool Parser::isCXXSimpleDeclaration() { 78 // C++ 6.8p1: 79 // There is an ambiguity in the grammar involving expression-statements and 80 // declarations: An expression-statement with a function-style explicit type 81 // conversion (5.2.3) as its leftmost subexpression can be indistinguishable 82 // from a declaration where the first declarator starts with a '('. In those 83 // cases the statement is a declaration. [Note: To disambiguate, the whole 84 // statement might have to be examined to determine if it is an 85 // expression-statement or a declaration]. 86 87 // C++ 6.8p3: 88 // The disambiguation is purely syntactic; that is, the meaning of the names 89 // occurring in such a statement, beyond whether they are type-names or not, 90 // is not generally used in or changed by the disambiguation. Class 91 // templates are instantiated as necessary to determine if a qualified name 92 // is a type-name. Disambiguation precedes parsing, and a statement 93 // disambiguated as a declaration may be an ill-formed declaration. 94 95 // We don't have to parse all of the decl-specifier-seq part. There's only 96 // an ambiguity if the first decl-specifier is 97 // simple-type-specifier/typename-specifier followed by a '(', which may 98 // indicate a function-style cast expression. 99 // isCXXDeclarationSpecifier will return TPResult::Ambiguous() only in such 100 // a case. 101 102 TPResult TPR = isCXXDeclarationSpecifier(); 103 if (TPR != TPResult::Ambiguous()) 104 return TPR != TPResult::False(); // Returns true for TPResult::True() or 105 // TPResult::Error(). 106 107 // FIXME: Add statistics about the number of ambiguous statements encountered 108 // and how they were resolved (number of declarations+number of expressions). 109 110 // Ok, we have a simple-type-specifier/typename-specifier followed by a '('. 111 // We need tentative parsing... 112 113 TentativeParsingAction PA(*this); 114 115 TPR = TryParseSimpleDeclaration(); 116 SourceLocation TentativeParseLoc = Tok.getLocation(); 117 118 PA.Revert(); 119 120 // In case of an error, let the declaration parsing code handle it. 121 if (TPR == TPResult::Error()) 122 return true; 123 124 // Declarations take precedence over expressions. 125 if (TPR == TPResult::Ambiguous()) 126 TPR = TPResult::True(); 127 128 assert(TPR == TPResult::True() || TPR == TPResult::False()); 129 return TPR == TPResult::True(); 130} 131 132/// simple-declaration: 133/// decl-specifier-seq init-declarator-list[opt] ';' 134/// 135Parser::TPResult Parser::TryParseSimpleDeclaration() { 136 // We know that we have a simple-type-specifier/typename-specifier followed 137 // by a '('. 138 assert(isCXXDeclarationSpecifier() == TPResult::Ambiguous()); 139 140 if (Tok.is(tok::kw_typeof)) 141 TryParseTypeofSpecifier(); 142 else 143 ConsumeToken(); 144 145 assert(Tok.is(tok::l_paren) && "Expected '('"); 146 147 TPResult TPR = TryParseInitDeclaratorList(); 148 if (TPR != TPResult::Ambiguous()) 149 return TPR; 150 151 if (Tok.isNot(tok::semi)) 152 return TPResult::False(); 153 154 return TPResult::Ambiguous(); 155} 156 157/// init-declarator-list: 158/// init-declarator 159/// init-declarator-list ',' init-declarator 160/// 161/// init-declarator: 162/// declarator initializer[opt] 163/// [GNU] declarator simple-asm-expr[opt] attributes[opt] initializer[opt] 164/// 165/// initializer: 166/// '=' initializer-clause 167/// '(' expression-list ')' 168/// 169/// initializer-clause: 170/// assignment-expression 171/// '{' initializer-list ','[opt] '}' 172/// '{' '}' 173/// 174Parser::TPResult Parser::TryParseInitDeclaratorList() { 175 // GCC only examines the first declarator for disambiguation: 176 // i.e: 177 // int(x), ++x; // GCC regards it as ill-formed declaration. 178 // 179 // Comeau and MSVC will regard the above statement as correct expression. 180 // Clang examines all of the declarators and also regards the above statement 181 // as correct expression. 182 183 while (1) { 184 // declarator 185 TPResult TPR = TryParseDeclarator(false/*mayBeAbstract*/); 186 if (TPR != TPResult::Ambiguous()) 187 return TPR; 188 189 // [GNU] simple-asm-expr[opt] attributes[opt] 190 if (Tok.is(tok::kw_asm) || Tok.is(tok::kw___attribute)) 191 return TPResult::True(); 192 193 // initializer[opt] 194 if (Tok.is(tok::l_paren)) { 195 // Parse through the parens. 196 ConsumeParen(); 197 if (!SkipUntil(tok::r_paren)) 198 return TPResult::Error(); 199 } else if (Tok.is(tok::equal)) { 200 // MSVC won't examine the rest of declarators if '=' is encountered, it 201 // will conclude that it is a declaration. 202 // Comeau and Clang will examine the rest of declarators. 203 // Note that "int(x) = {0}, ++x;" will be interpreted as ill-formed 204 // expression. 205 // 206 // Parse through the initializer-clause. 207 SkipUntil(tok::comma, true/*StopAtSemi*/, true/*DontConsume*/); 208 } 209 210 if (Tok.isNot(tok::comma)) 211 break; 212 ConsumeToken(); // the comma. 213 } 214 215 return TPResult::Ambiguous(); 216} 217 218/// isCXXConditionDeclaration - Disambiguates between a declaration or an 219/// expression for a condition of a if/switch/while/for statement. 220/// If during the disambiguation process a parsing error is encountered, 221/// the function returns true to let the declaration parsing code handle it. 222/// 223/// condition: 224/// expression 225/// type-specifier-seq declarator '=' assignment-expression 226/// [GNU] type-specifier-seq declarator simple-asm-expr[opt] attributes[opt] 227/// '=' assignment-expression 228/// 229bool Parser::isCXXConditionDeclaration() { 230 TPResult TPR = isCXXDeclarationSpecifier(); 231 if (TPR != TPResult::Ambiguous()) 232 return TPR != TPResult::False(); // Returns true for TPResult::True() or 233 // TPResult::Error(). 234 235 // FIXME: Add statistics about the number of ambiguous statements encountered 236 // and how they were resolved (number of declarations+number of expressions). 237 238 // Ok, we have a simple-type-specifier/typename-specifier followed by a '('. 239 // We need tentative parsing... 240 241 TentativeParsingAction PA(*this); 242 243 // type-specifier-seq 244 if (Tok.is(tok::kw_typeof)) 245 TryParseTypeofSpecifier(); 246 else 247 ConsumeToken(); 248 assert(Tok.is(tok::l_paren) && "Expected '('"); 249 250 // declarator 251 TPR = TryParseDeclarator(false/*mayBeAbstract*/); 252 253 // In case of an error, let the declaration parsing code handle it. 254 if (TPR == TPResult::Error()) 255 TPR = TPResult::True(); 256 257 if (TPR == TPResult::Ambiguous()) { 258 // '=' 259 // [GNU] simple-asm-expr[opt] attributes[opt] 260 if (Tok.is(tok::equal) || 261 Tok.is(tok::kw_asm) || Tok.is(tok::kw___attribute)) 262 TPR = TPResult::True(); 263 else 264 TPR = TPResult::False(); 265 } 266 267 PA.Revert(); 268 269 assert(TPR == TPResult::True() || TPR == TPResult::False()); 270 return TPR == TPResult::True(); 271} 272 273 /// \brief Determine whether the next set of tokens contains a type-id. 274 /// 275 /// The context parameter states what context we're parsing right 276 /// now, which affects how this routine copes with the token 277 /// following the type-id. If the context is TypeIdInParens, we have 278 /// already parsed the '(' and we will cease lookahead when we hit 279 /// the corresponding ')'. If the context is 280 /// TypeIdAsTemplateArgument, we've already parsed the '<' or ',' 281 /// before this template argument, and will cease lookahead when we 282 /// hit a '>', '>>' (in C++0x), or ','. Returns true for a type-id 283 /// and false for an expression. If during the disambiguation 284 /// process a parsing error is encountered, the function returns 285 /// true to let the declaration parsing code handle it. 286 /// 287 /// type-id: 288 /// type-specifier-seq abstract-declarator[opt] 289 /// 290bool Parser::isCXXTypeId(TentativeCXXTypeIdContext Context, bool &isAmbiguous) { 291 292 isAmbiguous = false; 293 294 // C++ 8.2p2: 295 // The ambiguity arising from the similarity between a function-style cast and 296 // a type-id can occur in different contexts. The ambiguity appears as a 297 // choice between a function-style cast expression and a declaration of a 298 // type. The resolution is that any construct that could possibly be a type-id 299 // in its syntactic context shall be considered a type-id. 300 301 TPResult TPR = isCXXDeclarationSpecifier(); 302 if (TPR != TPResult::Ambiguous()) 303 return TPR != TPResult::False(); // Returns true for TPResult::True() or 304 // TPResult::Error(). 305 306 // FIXME: Add statistics about the number of ambiguous statements encountered 307 // and how they were resolved (number of declarations+number of expressions). 308 309 // Ok, we have a simple-type-specifier/typename-specifier followed by a '('. 310 // We need tentative parsing... 311 312 TentativeParsingAction PA(*this); 313 314 // type-specifier-seq 315 if (Tok.is(tok::kw_typeof)) 316 TryParseTypeofSpecifier(); 317 else 318 ConsumeToken(); 319 assert(Tok.is(tok::l_paren) && "Expected '('"); 320 321 // declarator 322 TPR = TryParseDeclarator(true/*mayBeAbstract*/, false/*mayHaveIdentifier*/); 323 324 // In case of an error, let the declaration parsing code handle it. 325 if (TPR == TPResult::Error()) 326 TPR = TPResult::True(); 327 328 if (TPR == TPResult::Ambiguous()) { 329 // We are supposed to be inside parens, so if after the abstract declarator 330 // we encounter a ')' this is a type-id, otherwise it's an expression. 331 if (Context == TypeIdInParens && Tok.is(tok::r_paren)) { 332 TPR = TPResult::True(); 333 isAmbiguous = true; 334 335 // We are supposed to be inside a template argument, so if after 336 // the abstract declarator we encounter a '>', '>>' (in C++0x), or 337 // ',', this is a type-id. Otherwise, it's an expression. 338 } else if (Context == TypeIdAsTemplateArgument && 339 (Tok.is(tok::greater) || Tok.is(tok::comma) || 340 (getLang().CPlusPlus0x && Tok.is(tok::greatergreater)))) { 341 TPR = TPResult::True(); 342 isAmbiguous = true; 343 344 } else 345 TPR = TPResult::False(); 346 } 347 348 PA.Revert(); 349 350 assert(TPR == TPResult::True() || TPR == TPResult::False()); 351 return TPR == TPResult::True(); 352} 353 354/// declarator: 355/// direct-declarator 356/// ptr-operator declarator 357/// 358/// direct-declarator: 359/// declarator-id 360/// direct-declarator '(' parameter-declaration-clause ')' 361/// cv-qualifier-seq[opt] exception-specification[opt] 362/// direct-declarator '[' constant-expression[opt] ']' 363/// '(' declarator ')' 364/// [GNU] '(' attributes declarator ')' 365/// 366/// abstract-declarator: 367/// ptr-operator abstract-declarator[opt] 368/// direct-abstract-declarator 369/// 370/// direct-abstract-declarator: 371/// direct-abstract-declarator[opt] 372/// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 373/// exception-specification[opt] 374/// direct-abstract-declarator[opt] '[' constant-expression[opt] ']' 375/// '(' abstract-declarator ')' 376/// 377/// ptr-operator: 378/// '*' cv-qualifier-seq[opt] 379/// '&' 380/// [C++0x] '&&' [TODO] 381/// '::'[opt] nested-name-specifier '*' cv-qualifier-seq[opt] 382/// 383/// cv-qualifier-seq: 384/// cv-qualifier cv-qualifier-seq[opt] 385/// 386/// cv-qualifier: 387/// 'const' 388/// 'volatile' 389/// 390/// declarator-id: 391/// id-expression 392/// 393/// id-expression: 394/// unqualified-id 395/// qualified-id [TODO] 396/// 397/// unqualified-id: 398/// identifier 399/// operator-function-id [TODO] 400/// conversion-function-id [TODO] 401/// '~' class-name [TODO] 402/// template-id [TODO] 403/// 404Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract, 405 bool mayHaveIdentifier) { 406 // declarator: 407 // direct-declarator 408 // ptr-operator declarator 409 410 while (1) { 411 if (Tok.is(tok::coloncolon) || Tok.is(tok::identifier)) 412 TryAnnotateCXXScopeToken(); 413 414 if (Tok.is(tok::star) || Tok.is(tok::amp) || Tok.is(tok::caret) || 415 (Tok.is(tok::annot_cxxscope) && NextToken().is(tok::star))) { 416 // ptr-operator 417 ConsumeToken(); 418 while (Tok.is(tok::kw_const) || 419 Tok.is(tok::kw_volatile) || 420 Tok.is(tok::kw_restrict)) 421 ConsumeToken(); 422 } else { 423 break; 424 } 425 } 426 427 // direct-declarator: 428 // direct-abstract-declarator: 429 430 if (Tok.is(tok::identifier) && mayHaveIdentifier) { 431 // declarator-id 432 ConsumeToken(); 433 } else if (Tok.is(tok::l_paren)) { 434 ConsumeParen(); 435 if (mayBeAbstract && 436 (Tok.is(tok::r_paren) || // 'int()' is a function. 437 Tok.is(tok::ellipsis) || // 'int(...)' is a function. 438 isDeclarationSpecifier())) { // 'int(int)' is a function. 439 // '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 440 // exception-specification[opt] 441 TPResult TPR = TryParseFunctionDeclarator(); 442 if (TPR != TPResult::Ambiguous()) 443 return TPR; 444 } else { 445 // '(' declarator ')' 446 // '(' attributes declarator ')' 447 // '(' abstract-declarator ')' 448 if (Tok.is(tok::kw___attribute)) 449 return TPResult::True(); // attributes indicate declaration 450 TPResult TPR = TryParseDeclarator(mayBeAbstract, mayHaveIdentifier); 451 if (TPR != TPResult::Ambiguous()) 452 return TPR; 453 if (Tok.isNot(tok::r_paren)) 454 return TPResult::False(); 455 ConsumeParen(); 456 } 457 } else if (!mayBeAbstract) { 458 return TPResult::False(); 459 } 460 461 while (1) { 462 TPResult TPR(TPResult::Ambiguous()); 463 464 if (Tok.is(tok::l_paren)) { 465 // Check whether we have a function declarator or a possible ctor-style 466 // initializer that follows the declarator. Note that ctor-style 467 // initializers are not possible in contexts where abstract declarators 468 // are allowed. 469 if (!mayBeAbstract && !isCXXFunctionDeclarator(false/*warnIfAmbiguous*/)) 470 break; 471 472 // direct-declarator '(' parameter-declaration-clause ')' 473 // cv-qualifier-seq[opt] exception-specification[opt] 474 ConsumeParen(); 475 TPR = TryParseFunctionDeclarator(); 476 } else if (Tok.is(tok::l_square)) { 477 // direct-declarator '[' constant-expression[opt] ']' 478 // direct-abstract-declarator[opt] '[' constant-expression[opt] ']' 479 TPR = TryParseBracketDeclarator(); 480 } else { 481 break; 482 } 483 484 if (TPR != TPResult::Ambiguous()) 485 return TPR; 486 } 487 488 return TPResult::Ambiguous(); 489} 490 491/// isCXXDeclarationSpecifier - Returns TPResult::True() if it is a declaration 492/// specifier, TPResult::False() if it is not, TPResult::Ambiguous() if it could 493/// be either a decl-specifier or a function-style cast, and TPResult::Error() 494/// if a parsing error was found and reported. 495/// 496/// decl-specifier: 497/// storage-class-specifier 498/// type-specifier 499/// function-specifier 500/// 'friend' 501/// 'typedef' 502/// [GNU] attributes declaration-specifiers[opt] 503/// 504/// storage-class-specifier: 505/// 'register' 506/// 'static' 507/// 'extern' 508/// 'mutable' 509/// 'auto' 510/// [GNU] '__thread' 511/// 512/// function-specifier: 513/// 'inline' 514/// 'virtual' 515/// 'explicit' 516/// 517/// typedef-name: 518/// identifier 519/// 520/// type-specifier: 521/// simple-type-specifier 522/// class-specifier 523/// enum-specifier 524/// elaborated-type-specifier 525/// typename-specifier 526/// cv-qualifier 527/// 528/// simple-type-specifier: 529/// '::'[opt] nested-name-specifier[opt] type-name 530/// '::'[opt] nested-name-specifier 'template' 531/// simple-template-id [TODO] 532/// 'char' 533/// 'wchar_t' 534/// 'bool' 535/// 'short' 536/// 'int' 537/// 'long' 538/// 'signed' 539/// 'unsigned' 540/// 'float' 541/// 'double' 542/// 'void' 543/// [GNU] typeof-specifier 544/// [GNU] '_Complex' 545/// [C++0x] 'auto' [TODO] 546/// [C++0x] 'decltype' ( expression ) 547/// 548/// type-name: 549/// class-name 550/// enum-name 551/// typedef-name 552/// 553/// elaborated-type-specifier: 554/// class-key '::'[opt] nested-name-specifier[opt] identifier 555/// class-key '::'[opt] nested-name-specifier[opt] 'template'[opt] 556/// simple-template-id 557/// 'enum' '::'[opt] nested-name-specifier[opt] identifier 558/// 559/// enum-name: 560/// identifier 561/// 562/// enum-specifier: 563/// 'enum' identifier[opt] '{' enumerator-list[opt] '}' 564/// 'enum' identifier[opt] '{' enumerator-list ',' '}' 565/// 566/// class-specifier: 567/// class-head '{' member-specification[opt] '}' 568/// 569/// class-head: 570/// class-key identifier[opt] base-clause[opt] 571/// class-key nested-name-specifier identifier base-clause[opt] 572/// class-key nested-name-specifier[opt] simple-template-id 573/// base-clause[opt] 574/// 575/// class-key: 576/// 'class' 577/// 'struct' 578/// 'union' 579/// 580/// cv-qualifier: 581/// 'const' 582/// 'volatile' 583/// [GNU] restrict 584/// 585Parser::TPResult Parser::isCXXDeclarationSpecifier() { 586 switch (Tok.getKind()) { 587 case tok::identifier: // foo::bar 588 case tok::kw_typename: // typename T::type 589 // Annotate typenames and C++ scope specifiers. If we get one, just 590 // recurse to handle whatever we get. 591 if (TryAnnotateTypeOrScopeToken()) 592 return isCXXDeclarationSpecifier(); 593 // Otherwise, not a typename. 594 return TPResult::False(); 595 596 case tok::coloncolon: // ::foo::bar 597 if (NextToken().is(tok::kw_new) || // ::new 598 NextToken().is(tok::kw_delete)) // ::delete 599 return TPResult::False(); 600 601 // Annotate typenames and C++ scope specifiers. If we get one, just 602 // recurse to handle whatever we get. 603 if (TryAnnotateTypeOrScopeToken()) 604 return isCXXDeclarationSpecifier(); 605 // Otherwise, not a typename. 606 return TPResult::False(); 607 608 // decl-specifier: 609 // storage-class-specifier 610 // type-specifier 611 // function-specifier 612 // 'friend' 613 // 'typedef' 614 615 case tok::kw_friend: 616 case tok::kw_typedef: 617 // storage-class-specifier 618 case tok::kw_register: 619 case tok::kw_static: 620 case tok::kw_extern: 621 case tok::kw_mutable: 622 case tok::kw_auto: 623 case tok::kw___thread: 624 // function-specifier 625 case tok::kw_inline: 626 case tok::kw_virtual: 627 case tok::kw_explicit: 628 629 // type-specifier: 630 // simple-type-specifier 631 // class-specifier 632 // enum-specifier 633 // elaborated-type-specifier 634 // typename-specifier 635 // cv-qualifier 636 637 // class-specifier 638 // elaborated-type-specifier 639 case tok::kw_class: 640 case tok::kw_struct: 641 case tok::kw_union: 642 // enum-specifier 643 case tok::kw_enum: 644 // cv-qualifier 645 case tok::kw_const: 646 case tok::kw_volatile: 647 648 // GNU 649 case tok::kw_restrict: 650 case tok::kw__Complex: 651 case tok::kw___attribute: 652 return TPResult::True(); 653 654 // Microsoft 655 case tok::kw___declspec: 656 case tok::kw___cdecl: 657 case tok::kw___stdcall: 658 case tok::kw___fastcall: 659 case tok::kw___w64: 660 case tok::kw___ptr64: 661 case tok::kw___forceinline: 662 return TPResult::True(); 663 664 // The ambiguity resides in a simple-type-specifier/typename-specifier 665 // followed by a '('. The '(' could either be the start of: 666 // 667 // direct-declarator: 668 // '(' declarator ')' 669 // 670 // direct-abstract-declarator: 671 // '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 672 // exception-specification[opt] 673 // '(' abstract-declarator ')' 674 // 675 // or part of a function-style cast expression: 676 // 677 // simple-type-specifier '(' expression-list[opt] ')' 678 // 679 680 // simple-type-specifier: 681 682 case tok::kw_char: 683 case tok::kw_wchar_t: 684 case tok::kw_char16_t: 685 case tok::kw_char32_t: 686 case tok::kw_bool: 687 case tok::kw_short: 688 case tok::kw_int: 689 case tok::kw_long: 690 case tok::kw_signed: 691 case tok::kw_unsigned: 692 case tok::kw_float: 693 case tok::kw_double: 694 case tok::kw_void: 695 case tok::annot_typename: 696 if (NextToken().is(tok::l_paren)) 697 return TPResult::Ambiguous(); 698 699 return TPResult::True(); 700 701 // GNU typeof support. 702 case tok::kw_typeof: { 703 if (NextToken().isNot(tok::l_paren)) 704 return TPResult::True(); 705 706 TentativeParsingAction PA(*this); 707 708 TPResult TPR = TryParseTypeofSpecifier(); 709 bool isFollowedByParen = Tok.is(tok::l_paren); 710 711 PA.Revert(); 712 713 if (TPR == TPResult::Error()) 714 return TPResult::Error(); 715 716 if (isFollowedByParen) 717 return TPResult::Ambiguous(); 718 719 return TPResult::True(); 720 } 721 722 // C++0x decltype support. 723 case tok::kw_decltype: 724 return TPResult::True(); 725 726 default: 727 return TPResult::False(); 728 } 729} 730 731/// [GNU] typeof-specifier: 732/// 'typeof' '(' expressions ')' 733/// 'typeof' '(' type-name ')' 734/// 735Parser::TPResult Parser::TryParseTypeofSpecifier() { 736 assert(Tok.is(tok::kw_typeof) && "Expected 'typeof'!"); 737 ConsumeToken(); 738 739 assert(Tok.is(tok::l_paren) && "Expected '('"); 740 // Parse through the parens after 'typeof'. 741 ConsumeParen(); 742 if (!SkipUntil(tok::r_paren)) 743 return TPResult::Error(); 744 745 return TPResult::Ambiguous(); 746} 747 748Parser::TPResult Parser::TryParseDeclarationSpecifier() { 749 TPResult TPR = isCXXDeclarationSpecifier(); 750 if (TPR != TPResult::Ambiguous()) 751 return TPR; 752 753 if (Tok.is(tok::kw_typeof)) 754 TryParseTypeofSpecifier(); 755 else 756 ConsumeToken(); 757 758 assert(Tok.is(tok::l_paren) && "Expected '('!"); 759 return TPResult::Ambiguous(); 760} 761 762/// isCXXFunctionDeclarator - Disambiguates between a function declarator or 763/// a constructor-style initializer, when parsing declaration statements. 764/// Returns true for function declarator and false for constructor-style 765/// initializer. 766/// If during the disambiguation process a parsing error is encountered, 767/// the function returns true to let the declaration parsing code handle it. 768/// 769/// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 770/// exception-specification[opt] 771/// 772bool Parser::isCXXFunctionDeclarator(bool warnIfAmbiguous) { 773 774 // C++ 8.2p1: 775 // The ambiguity arising from the similarity between a function-style cast and 776 // a declaration mentioned in 6.8 can also occur in the context of a 777 // declaration. In that context, the choice is between a function declaration 778 // with a redundant set of parentheses around a parameter name and an object 779 // declaration with a function-style cast as the initializer. Just as for the 780 // ambiguities mentioned in 6.8, the resolution is to consider any construct 781 // that could possibly be a declaration a declaration. 782 783 TentativeParsingAction PA(*this); 784 785 ConsumeParen(); 786 TPResult TPR = TryParseParameterDeclarationClause(); 787 if (TPR == TPResult::Ambiguous() && Tok.isNot(tok::r_paren)) 788 TPR = TPResult::False(); 789 790 SourceLocation TPLoc = Tok.getLocation(); 791 PA.Revert(); 792 793 // In case of an error, let the declaration parsing code handle it. 794 if (TPR == TPResult::Error()) 795 return true; 796 797 if (TPR == TPResult::Ambiguous()) { 798 // Function declarator has precedence over constructor-style initializer. 799 // Emit a warning just in case the author intended a variable definition. 800 if (warnIfAmbiguous) 801 Diag(Tok, diag::warn_parens_disambiguated_as_function_decl) 802 << SourceRange(Tok.getLocation(), TPLoc); 803 return true; 804 } 805 806 return TPR == TPResult::True(); 807} 808 809/// parameter-declaration-clause: 810/// parameter-declaration-list[opt] '...'[opt] 811/// parameter-declaration-list ',' '...' 812/// 813/// parameter-declaration-list: 814/// parameter-declaration 815/// parameter-declaration-list ',' parameter-declaration 816/// 817/// parameter-declaration: 818/// decl-specifier-seq declarator 819/// decl-specifier-seq declarator '=' assignment-expression 820/// decl-specifier-seq abstract-declarator[opt] 821/// decl-specifier-seq abstract-declarator[opt] '=' assignment-expression 822/// 823Parser::TPResult Parser::TryParseParameterDeclarationClause() { 824 825 if (Tok.is(tok::r_paren)) 826 return TPResult::True(); 827 828 // parameter-declaration-list[opt] '...'[opt] 829 // parameter-declaration-list ',' '...' 830 // 831 // parameter-declaration-list: 832 // parameter-declaration 833 // parameter-declaration-list ',' parameter-declaration 834 // 835 while (1) { 836 // '...'[opt] 837 if (Tok.is(tok::ellipsis)) { 838 ConsumeToken(); 839 return TPResult::True(); // '...' is a sign of a function declarator. 840 } 841 842 // decl-specifier-seq 843 TPResult TPR = TryParseDeclarationSpecifier(); 844 if (TPR != TPResult::Ambiguous()) 845 return TPR; 846 847 // declarator 848 // abstract-declarator[opt] 849 TPR = TryParseDeclarator(true/*mayBeAbstract*/); 850 if (TPR != TPResult::Ambiguous()) 851 return TPR; 852 853 if (Tok.is(tok::equal)) { 854 // '=' assignment-expression 855 // Parse through assignment-expression. 856 tok::TokenKind StopToks[3] ={ tok::comma, tok::ellipsis, tok::r_paren }; 857 if (!SkipUntil(StopToks, 3, true/*StopAtSemi*/, true/*DontConsume*/)) 858 return TPResult::Error(); 859 } 860 861 if (Tok.is(tok::ellipsis)) { 862 ConsumeToken(); 863 return TPResult::True(); // '...' is a sign of a function declarator. 864 } 865 866 if (Tok.isNot(tok::comma)) 867 break; 868 ConsumeToken(); // the comma. 869 } 870 871 return TPResult::Ambiguous(); 872} 873 874/// TryParseFunctionDeclarator - We parsed a '(' and we want to try to continue 875/// parsing as a function declarator. 876/// If TryParseFunctionDeclarator fully parsed the function declarator, it will 877/// return TPResult::Ambiguous(), otherwise it will return either False() or 878/// Error(). 879/// 880/// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 881/// exception-specification[opt] 882/// 883/// exception-specification: 884/// 'throw' '(' type-id-list[opt] ')' 885/// 886Parser::TPResult Parser::TryParseFunctionDeclarator() { 887 888 // The '(' is already parsed. 889 890 TPResult TPR = TryParseParameterDeclarationClause(); 891 if (TPR == TPResult::Ambiguous() && Tok.isNot(tok::r_paren)) 892 TPR = TPResult::False(); 893 894 if (TPR == TPResult::False() || TPR == TPResult::Error()) 895 return TPR; 896 897 // Parse through the parens. 898 if (!SkipUntil(tok::r_paren)) 899 return TPResult::Error(); 900 901 // cv-qualifier-seq 902 while (Tok.is(tok::kw_const) || 903 Tok.is(tok::kw_volatile) || 904 Tok.is(tok::kw_restrict) ) 905 ConsumeToken(); 906 907 // exception-specification 908 if (Tok.is(tok::kw_throw)) { 909 ConsumeToken(); 910 if (Tok.isNot(tok::l_paren)) 911 return TPResult::Error(); 912 913 // Parse through the parens after 'throw'. 914 ConsumeParen(); 915 if (!SkipUntil(tok::r_paren)) 916 return TPResult::Error(); 917 } 918 919 return TPResult::Ambiguous(); 920} 921 922/// '[' constant-expression[opt] ']' 923/// 924Parser::TPResult Parser::TryParseBracketDeclarator() { 925 ConsumeBracket(); 926 if (!SkipUntil(tok::r_square)) 927 return TPResult::Error(); 928 929 return TPResult::Ambiguous(); 930} 931