ParseTentative.cpp revision d57959af02b4af695276f4204443afe6e5d86bd8
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) { 291 292 // C++ 8.2p2: 293 // The ambiguity arising from the similarity between a function-style cast and 294 // a type-id can occur in different contexts. The ambiguity appears as a 295 // choice between a function-style cast expression and a declaration of a 296 // type. The resolution is that any construct that could possibly be a type-id 297 // in its syntactic context shall be considered a type-id. 298 299 TPResult TPR = isCXXDeclarationSpecifier(); 300 if (TPR != TPResult::Ambiguous()) 301 return TPR != TPResult::False(); // Returns true for TPResult::True() or 302 // TPResult::Error(). 303 304 // FIXME: Add statistics about the number of ambiguous statements encountered 305 // and how they were resolved (number of declarations+number of expressions). 306 307 // Ok, we have a simple-type-specifier/typename-specifier followed by a '('. 308 // We need tentative parsing... 309 310 TentativeParsingAction PA(*this); 311 312 // type-specifier-seq 313 if (Tok.is(tok::kw_typeof)) 314 TryParseTypeofSpecifier(); 315 else 316 ConsumeToken(); 317 assert(Tok.is(tok::l_paren) && "Expected '('"); 318 319 // declarator 320 TPR = TryParseDeclarator(true/*mayBeAbstract*/, false/*mayHaveIdentifier*/); 321 322 // In case of an error, let the declaration parsing code handle it. 323 if (TPR == TPResult::Error()) 324 TPR = TPResult::True(); 325 326 if (TPR == TPResult::Ambiguous()) { 327 // We are supposed to be inside parens, so if after the abstract declarator 328 // we encounter a ')' this is a type-id, otherwise it's an expression. 329 if (Context == TypeIdInParens && Tok.is(tok::r_paren)) 330 TPR = TPResult::True(); 331 // We are supposed to be inside a template argument, so if after 332 // the abstract declarator we encounter a '>', '>>' (in C++0x), or 333 // ',', this is a type-id. Otherwise, it's an expression. 334 else if (Context == TypeIdAsTemplateArgument && 335 (Tok.is(tok::greater) || Tok.is(tok::comma) || 336 (getLang().CPlusPlus0x && Tok.is(tok::greatergreater)))) 337 TPR = TPResult::True(); 338 else 339 TPR = TPResult::False(); 340 } 341 342 PA.Revert(); 343 344 assert(TPR == TPResult::True() || TPR == TPResult::False()); 345 return TPR == TPResult::True(); 346} 347 348/// declarator: 349/// direct-declarator 350/// ptr-operator declarator 351/// 352/// direct-declarator: 353/// declarator-id 354/// direct-declarator '(' parameter-declaration-clause ')' 355/// cv-qualifier-seq[opt] exception-specification[opt] 356/// direct-declarator '[' constant-expression[opt] ']' 357/// '(' declarator ')' 358/// [GNU] '(' attributes declarator ')' 359/// 360/// abstract-declarator: 361/// ptr-operator abstract-declarator[opt] 362/// direct-abstract-declarator 363/// 364/// direct-abstract-declarator: 365/// direct-abstract-declarator[opt] 366/// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 367/// exception-specification[opt] 368/// direct-abstract-declarator[opt] '[' constant-expression[opt] ']' 369/// '(' abstract-declarator ')' 370/// 371/// ptr-operator: 372/// '*' cv-qualifier-seq[opt] 373/// '&' 374/// [C++0x] '&&' [TODO] 375/// '::'[opt] nested-name-specifier '*' cv-qualifier-seq[opt] 376/// 377/// cv-qualifier-seq: 378/// cv-qualifier cv-qualifier-seq[opt] 379/// 380/// cv-qualifier: 381/// 'const' 382/// 'volatile' 383/// 384/// declarator-id: 385/// id-expression 386/// 387/// id-expression: 388/// unqualified-id 389/// qualified-id [TODO] 390/// 391/// unqualified-id: 392/// identifier 393/// operator-function-id [TODO] 394/// conversion-function-id [TODO] 395/// '~' class-name [TODO] 396/// template-id [TODO] 397/// 398Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract, 399 bool mayHaveIdentifier) { 400 // declarator: 401 // direct-declarator 402 // ptr-operator declarator 403 404 while (1) { 405 if (Tok.is(tok::coloncolon) || Tok.is(tok::identifier)) 406 TryAnnotateCXXScopeToken(); 407 408 if (Tok.is(tok::star) || Tok.is(tok::amp) || Tok.is(tok::caret) || 409 (Tok.is(tok::annot_cxxscope) && NextToken().is(tok::star))) { 410 // ptr-operator 411 ConsumeToken(); 412 while (Tok.is(tok::kw_const) || 413 Tok.is(tok::kw_volatile) || 414 Tok.is(tok::kw_restrict)) 415 ConsumeToken(); 416 } else { 417 break; 418 } 419 } 420 421 // direct-declarator: 422 // direct-abstract-declarator: 423 424 if (Tok.is(tok::identifier) && mayHaveIdentifier) { 425 // declarator-id 426 ConsumeToken(); 427 } else if (Tok.is(tok::l_paren)) { 428 ConsumeParen(); 429 if (mayBeAbstract && 430 (Tok.is(tok::r_paren) || // 'int()' is a function. 431 Tok.is(tok::ellipsis) || // 'int(...)' is a function. 432 isDeclarationSpecifier())) { // 'int(int)' is a function. 433 // '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 434 // exception-specification[opt] 435 TPResult TPR = TryParseFunctionDeclarator(); 436 if (TPR != TPResult::Ambiguous()) 437 return TPR; 438 } else { 439 // '(' declarator ')' 440 // '(' attributes declarator ')' 441 // '(' abstract-declarator ')' 442 if (Tok.is(tok::kw___attribute)) 443 return TPResult::True(); // attributes indicate declaration 444 TPResult TPR = TryParseDeclarator(mayBeAbstract, mayHaveIdentifier); 445 if (TPR != TPResult::Ambiguous()) 446 return TPR; 447 if (Tok.isNot(tok::r_paren)) 448 return TPResult::False(); 449 ConsumeParen(); 450 } 451 } else if (!mayBeAbstract) { 452 return TPResult::False(); 453 } 454 455 while (1) { 456 TPResult TPR(TPResult::Ambiguous()); 457 458 if (Tok.is(tok::l_paren)) { 459 // Check whether we have a function declarator or a possible ctor-style 460 // initializer that follows the declarator. Note that ctor-style 461 // initializers are not possible in contexts where abstract declarators 462 // are allowed. 463 if (!mayBeAbstract && !isCXXFunctionDeclarator(false/*warnIfAmbiguous*/)) 464 break; 465 466 // direct-declarator '(' parameter-declaration-clause ')' 467 // cv-qualifier-seq[opt] exception-specification[opt] 468 ConsumeParen(); 469 TPR = TryParseFunctionDeclarator(); 470 } else if (Tok.is(tok::l_square)) { 471 // direct-declarator '[' constant-expression[opt] ']' 472 // direct-abstract-declarator[opt] '[' constant-expression[opt] ']' 473 TPR = TryParseBracketDeclarator(); 474 } else { 475 break; 476 } 477 478 if (TPR != TPResult::Ambiguous()) 479 return TPR; 480 } 481 482 return TPResult::Ambiguous(); 483} 484 485/// isCXXDeclarationSpecifier - Returns TPResult::True() if it is a declaration 486/// specifier, TPResult::False() if it is not, TPResult::Ambiguous() if it could 487/// be either a decl-specifier or a function-style cast, and TPResult::Error() 488/// if a parsing error was found and reported. 489/// 490/// decl-specifier: 491/// storage-class-specifier 492/// type-specifier 493/// function-specifier 494/// 'friend' 495/// 'typedef' 496/// [GNU] attributes declaration-specifiers[opt] 497/// 498/// storage-class-specifier: 499/// 'register' 500/// 'static' 501/// 'extern' 502/// 'mutable' 503/// 'auto' 504/// [GNU] '__thread' 505/// 506/// function-specifier: 507/// 'inline' 508/// 'virtual' 509/// 'explicit' 510/// 511/// typedef-name: 512/// identifier 513/// 514/// type-specifier: 515/// simple-type-specifier 516/// class-specifier 517/// enum-specifier 518/// elaborated-type-specifier 519/// typename-specifier 520/// cv-qualifier 521/// 522/// simple-type-specifier: 523/// '::'[opt] nested-name-specifier[opt] type-name 524/// '::'[opt] nested-name-specifier 'template' 525/// simple-template-id [TODO] 526/// 'char' 527/// 'wchar_t' 528/// 'bool' 529/// 'short' 530/// 'int' 531/// 'long' 532/// 'signed' 533/// 'unsigned' 534/// 'float' 535/// 'double' 536/// 'void' 537/// [GNU] typeof-specifier 538/// [GNU] '_Complex' 539/// [C++0x] 'auto' [TODO] 540/// 541/// type-name: 542/// class-name 543/// enum-name 544/// typedef-name 545/// 546/// elaborated-type-specifier: 547/// class-key '::'[opt] nested-name-specifier[opt] identifier 548/// class-key '::'[opt] nested-name-specifier[opt] 'template'[opt] 549/// simple-template-id 550/// 'enum' '::'[opt] nested-name-specifier[opt] identifier 551/// 552/// enum-name: 553/// identifier 554/// 555/// enum-specifier: 556/// 'enum' identifier[opt] '{' enumerator-list[opt] '}' 557/// 'enum' identifier[opt] '{' enumerator-list ',' '}' 558/// 559/// class-specifier: 560/// class-head '{' member-specification[opt] '}' 561/// 562/// class-head: 563/// class-key identifier[opt] base-clause[opt] 564/// class-key nested-name-specifier identifier base-clause[opt] 565/// class-key nested-name-specifier[opt] simple-template-id 566/// base-clause[opt] 567/// 568/// class-key: 569/// 'class' 570/// 'struct' 571/// 'union' 572/// 573/// cv-qualifier: 574/// 'const' 575/// 'volatile' 576/// [GNU] restrict 577/// 578Parser::TPResult Parser::isCXXDeclarationSpecifier() { 579 switch (Tok.getKind()) { 580 case tok::identifier: // foo::bar 581 case tok::kw_typename: // typename T::type 582 // Annotate typenames and C++ scope specifiers. If we get one, just 583 // recurse to handle whatever we get. 584 if (TryAnnotateTypeOrScopeToken()) 585 return isCXXDeclarationSpecifier(); 586 // Otherwise, not a typename. 587 return TPResult::False(); 588 589 case tok::coloncolon: // ::foo::bar 590 if (NextToken().is(tok::kw_new) || // ::new 591 NextToken().is(tok::kw_delete)) // ::delete 592 return TPResult::False(); 593 594 // Annotate typenames and C++ scope specifiers. If we get one, just 595 // recurse to handle whatever we get. 596 if (TryAnnotateTypeOrScopeToken()) 597 return isCXXDeclarationSpecifier(); 598 // Otherwise, not a typename. 599 return TPResult::False(); 600 601 // decl-specifier: 602 // storage-class-specifier 603 // type-specifier 604 // function-specifier 605 // 'friend' 606 // 'typedef' 607 608 case tok::kw_friend: 609 case tok::kw_typedef: 610 // storage-class-specifier 611 case tok::kw_register: 612 case tok::kw_static: 613 case tok::kw_extern: 614 case tok::kw_mutable: 615 case tok::kw_auto: 616 case tok::kw___thread: 617 // function-specifier 618 case tok::kw_inline: 619 case tok::kw_virtual: 620 case tok::kw_explicit: 621 622 // type-specifier: 623 // simple-type-specifier 624 // class-specifier 625 // enum-specifier 626 // elaborated-type-specifier 627 // typename-specifier 628 // cv-qualifier 629 630 // class-specifier 631 // elaborated-type-specifier 632 case tok::kw_class: 633 case tok::kw_struct: 634 case tok::kw_union: 635 // enum-specifier 636 case tok::kw_enum: 637 // cv-qualifier 638 case tok::kw_const: 639 case tok::kw_volatile: 640 641 // GNU 642 case tok::kw_restrict: 643 case tok::kw__Complex: 644 case tok::kw___attribute: 645 return TPResult::True(); 646 647 // Microsoft 648 case tok::kw___declspec: 649 case tok::kw___cdecl: 650 case tok::kw___stdcall: 651 case tok::kw___fastcall: 652 return PP.getLangOptions().Microsoft ? TPResult::True() : TPResult::False(); 653 654 // The ambiguity resides in a simple-type-specifier/typename-specifier 655 // followed by a '('. The '(' could either be the start of: 656 // 657 // direct-declarator: 658 // '(' declarator ')' 659 // 660 // direct-abstract-declarator: 661 // '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 662 // exception-specification[opt] 663 // '(' abstract-declarator ')' 664 // 665 // or part of a function-style cast expression: 666 // 667 // simple-type-specifier '(' expression-list[opt] ')' 668 // 669 670 // simple-type-specifier: 671 672 case tok::kw_char: 673 case tok::kw_wchar_t: 674 case tok::kw_bool: 675 case tok::kw_short: 676 case tok::kw_int: 677 case tok::kw_long: 678 case tok::kw_signed: 679 case tok::kw_unsigned: 680 case tok::kw_float: 681 case tok::kw_double: 682 case tok::kw_void: 683 case tok::annot_typename: 684 if (NextToken().is(tok::l_paren)) 685 return TPResult::Ambiguous(); 686 687 return TPResult::True(); 688 689 // GNU typeof support. 690 case tok::kw_typeof: { 691 if (NextToken().isNot(tok::l_paren)) 692 return TPResult::True(); 693 694 TentativeParsingAction PA(*this); 695 696 TPResult TPR = TryParseTypeofSpecifier(); 697 bool isFollowedByParen = Tok.is(tok::l_paren); 698 699 PA.Revert(); 700 701 if (TPR == TPResult::Error()) 702 return TPResult::Error(); 703 704 if (isFollowedByParen) 705 return TPResult::Ambiguous(); 706 707 return TPResult::True(); 708 } 709 710 default: 711 return TPResult::False(); 712 } 713} 714 715/// [GNU] typeof-specifier: 716/// 'typeof' '(' expressions ')' 717/// 'typeof' '(' type-name ')' 718/// 719Parser::TPResult Parser::TryParseTypeofSpecifier() { 720 assert(Tok.is(tok::kw_typeof) && "Expected 'typeof'!"); 721 ConsumeToken(); 722 723 assert(Tok.is(tok::l_paren) && "Expected '('"); 724 // Parse through the parens after 'typeof'. 725 ConsumeParen(); 726 if (!SkipUntil(tok::r_paren)) 727 return TPResult::Error(); 728 729 return TPResult::Ambiguous(); 730} 731 732Parser::TPResult Parser::TryParseDeclarationSpecifier() { 733 TPResult TPR = isCXXDeclarationSpecifier(); 734 if (TPR != TPResult::Ambiguous()) 735 return TPR; 736 737 if (Tok.is(tok::kw_typeof)) 738 TryParseTypeofSpecifier(); 739 else 740 ConsumeToken(); 741 742 assert(Tok.is(tok::l_paren) && "Expected '('!"); 743 return TPResult::Ambiguous(); 744} 745 746/// isCXXFunctionDeclarator - Disambiguates between a function declarator or 747/// a constructor-style initializer, when parsing declaration statements. 748/// Returns true for function declarator and false for constructor-style 749/// initializer. 750/// If during the disambiguation process a parsing error is encountered, 751/// the function returns true to let the declaration parsing code handle it. 752/// 753/// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 754/// exception-specification[opt] 755/// 756bool Parser::isCXXFunctionDeclarator(bool warnIfAmbiguous) { 757 758 // C++ 8.2p1: 759 // The ambiguity arising from the similarity between a function-style cast and 760 // a declaration mentioned in 6.8 can also occur in the context of a 761 // declaration. In that context, the choice is between a function declaration 762 // with a redundant set of parentheses around a parameter name and an object 763 // declaration with a function-style cast as the initializer. Just as for the 764 // ambiguities mentioned in 6.8, the resolution is to consider any construct 765 // that could possibly be a declaration a declaration. 766 767 TentativeParsingAction PA(*this); 768 769 ConsumeParen(); 770 TPResult TPR = TryParseParameterDeclarationClause(); 771 if (TPR == TPResult::Ambiguous() && Tok.isNot(tok::r_paren)) 772 TPR = TPResult::False(); 773 774 SourceLocation TPLoc = Tok.getLocation(); 775 PA.Revert(); 776 777 // In case of an error, let the declaration parsing code handle it. 778 if (TPR == TPResult::Error()) 779 return true; 780 781 if (TPR == TPResult::Ambiguous()) { 782 // Function declarator has precedence over constructor-style initializer. 783 // Emit a warning just in case the author intended a variable definition. 784 if (warnIfAmbiguous) 785 Diag(Tok, diag::warn_parens_disambiguated_as_function_decl) 786 << SourceRange(Tok.getLocation(), TPLoc); 787 return true; 788 } 789 790 return TPR == TPResult::True(); 791} 792 793/// parameter-declaration-clause: 794/// parameter-declaration-list[opt] '...'[opt] 795/// parameter-declaration-list ',' '...' 796/// 797/// parameter-declaration-list: 798/// parameter-declaration 799/// parameter-declaration-list ',' parameter-declaration 800/// 801/// parameter-declaration: 802/// decl-specifier-seq declarator 803/// decl-specifier-seq declarator '=' assignment-expression 804/// decl-specifier-seq abstract-declarator[opt] 805/// decl-specifier-seq abstract-declarator[opt] '=' assignment-expression 806/// 807Parser::TPResult Parser::TryParseParameterDeclarationClause() { 808 809 if (Tok.is(tok::r_paren)) 810 return TPResult::True(); 811 812 // parameter-declaration-list[opt] '...'[opt] 813 // parameter-declaration-list ',' '...' 814 // 815 // parameter-declaration-list: 816 // parameter-declaration 817 // parameter-declaration-list ',' parameter-declaration 818 // 819 while (1) { 820 // '...'[opt] 821 if (Tok.is(tok::ellipsis)) { 822 ConsumeToken(); 823 return TPResult::True(); // '...' is a sign of a function declarator. 824 } 825 826 // decl-specifier-seq 827 TPResult TPR = TryParseDeclarationSpecifier(); 828 if (TPR != TPResult::Ambiguous()) 829 return TPR; 830 831 // declarator 832 // abstract-declarator[opt] 833 TPR = TryParseDeclarator(true/*mayBeAbstract*/); 834 if (TPR != TPResult::Ambiguous()) 835 return TPR; 836 837 if (Tok.is(tok::equal)) { 838 // '=' assignment-expression 839 // Parse through assignment-expression. 840 tok::TokenKind StopToks[3] ={ tok::comma, tok::ellipsis, tok::r_paren }; 841 if (!SkipUntil(StopToks, 3, true/*StopAtSemi*/, true/*DontConsume*/)) 842 return TPResult::Error(); 843 } 844 845 if (Tok.is(tok::ellipsis)) { 846 ConsumeToken(); 847 return TPResult::True(); // '...' is a sign of a function declarator. 848 } 849 850 if (Tok.isNot(tok::comma)) 851 break; 852 ConsumeToken(); // the comma. 853 } 854 855 return TPResult::Ambiguous(); 856} 857 858/// TryParseFunctionDeclarator - We parsed a '(' and we want to try to continue 859/// parsing as a function declarator. 860/// If TryParseFunctionDeclarator fully parsed the function declarator, it will 861/// return TPResult::Ambiguous(), otherwise it will return either False() or 862/// Error(). 863/// 864/// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] 865/// exception-specification[opt] 866/// 867/// exception-specification: 868/// 'throw' '(' type-id-list[opt] ')' 869/// 870Parser::TPResult Parser::TryParseFunctionDeclarator() { 871 872 // The '(' is already parsed. 873 874 TPResult TPR = TryParseParameterDeclarationClause(); 875 if (TPR == TPResult::Ambiguous() && Tok.isNot(tok::r_paren)) 876 TPR = TPResult::False(); 877 878 if (TPR == TPResult::False() || TPR == TPResult::Error()) 879 return TPR; 880 881 // Parse through the parens. 882 if (!SkipUntil(tok::r_paren)) 883 return TPResult::Error(); 884 885 // cv-qualifier-seq 886 while (Tok.is(tok::kw_const) || 887 Tok.is(tok::kw_volatile) || 888 Tok.is(tok::kw_restrict) ) 889 ConsumeToken(); 890 891 // exception-specification 892 if (Tok.is(tok::kw_throw)) { 893 ConsumeToken(); 894 if (Tok.isNot(tok::l_paren)) 895 return TPResult::Error(); 896 897 // Parse through the parens after 'throw'. 898 ConsumeParen(); 899 if (!SkipUntil(tok::r_paren)) 900 return TPResult::Error(); 901 } 902 903 return TPResult::Ambiguous(); 904} 905 906/// '[' constant-expression[opt] ']' 907/// 908Parser::TPResult Parser::TryParseBracketDeclarator() { 909 ConsumeBracket(); 910 if (!SkipUntil(tok::r_square)) 911 return TPResult::Error(); 912 913 return TPResult::Ambiguous(); 914} 915