ParseTentative.cpp revision 25a767651d14db87aa03dd5fe3e011d877dd4100 
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"
17#include "clang/Sema/ParsedTemplate.h"
18using namespace clang;
19
20/// isCXXDeclarationStatement - C++-specialized function that disambiguates
21/// between a declaration or an expression statement, when parsing function
22/// bodies. Returns true for declaration, false for expression.
23///
24///         declaration-statement:
25///           block-declaration
26///
27///         block-declaration:
28///           simple-declaration
29///           asm-definition
30///           namespace-alias-definition
31///           using-declaration
32///           using-directive
33/// [C++0x]   static_assert-declaration
34///
35///         asm-definition:
36///           'asm' '(' string-literal ')' ';'
37///
38///         namespace-alias-definition:
39///           'namespace' identifier = qualified-namespace-specifier ';'
40///
41///         using-declaration:
42///           'using' typename[opt] '::'[opt] nested-name-specifier
43///                 unqualified-id ';'
44///           'using' '::' unqualified-id ;
45///
46///         using-directive:
47///           'using' 'namespace' '::'[opt] nested-name-specifier[opt]
48///                 namespace-name ';'
49///
50bool Parser::isCXXDeclarationStatement() {
51  switch (Tok.getKind()) {
52    // asm-definition
53  case tok::kw_asm:
54    // namespace-alias-definition
55  case tok::kw_namespace:
56    // using-declaration
57    // using-directive
58  case tok::kw_using:
59    // static_assert-declaration
60  case tok::kw_static_assert:
61  case tok::kw__Static_assert:
62    return true;
63    // simple-declaration
64  default:
65    return isCXXSimpleDeclaration();
66  }
67}
68
69/// isCXXSimpleDeclaration - C++-specialized function that disambiguates
70/// between a simple-declaration or an expression-statement.
71/// If during the disambiguation process a parsing error is encountered,
72/// the function returns true to let the declaration parsing code handle it.
73/// Returns false if the statement is disambiguated as expression.
74///
75/// simple-declaration:
76///   decl-specifier-seq init-declarator-list[opt] ';'
77///
78bool Parser::isCXXSimpleDeclaration() {
79  // C++ 6.8p1:
80  // There is an ambiguity in the grammar involving expression-statements and
81  // declarations: An expression-statement with a function-style explicit type
82  // conversion (5.2.3) as its leftmost subexpression can be indistinguishable
83  // from a declaration where the first declarator starts with a '('. In those
84  // cases the statement is a declaration. [Note: To disambiguate, the whole
85  // statement might have to be examined to determine if it is an
86  // expression-statement or a declaration].
87
88  // C++ 6.8p3:
89  // The disambiguation is purely syntactic; that is, the meaning of the names
90  // occurring in such a statement, beyond whether they are type-names or not,
91  // is not generally used in or changed by the disambiguation. Class
92  // templates are instantiated as necessary to determine if a qualified name
93  // is a type-name. Disambiguation precedes parsing, and a statement
94  // disambiguated as a declaration may be an ill-formed declaration.
95
96  // We don't have to parse all of the decl-specifier-seq part. There's only
97  // an ambiguity if the first decl-specifier is
98  // simple-type-specifier/typename-specifier followed by a '(', which may
99  // indicate a function-style cast expression.
100  // isCXXDeclarationSpecifier will return TPResult::Ambiguous() only in such
101  // a case.
102
103  TPResult TPR = isCXXDeclarationSpecifier();
104  if (TPR != TPResult::Ambiguous())
105    return TPR != TPResult::False(); // Returns true for TPResult::True() or
106                                     // TPResult::Error().
107
108  // FIXME: Add statistics about the number of ambiguous statements encountered
109  // and how they were resolved (number of declarations+number of expressions).
110
111  // Ok, we have a simple-type-specifier/typename-specifier followed by a '('.
112  // We need tentative parsing...
113
114  TentativeParsingAction PA(*this);
115  TPR = TryParseSimpleDeclaration();
116  PA.Revert();
117
118  // In case of an error, let the declaration parsing code handle it.
119  if (TPR == TPResult::Error())
120    return true;
121
122  // Declarations take precedence over expressions.
123  if (TPR == TPResult::Ambiguous())
124    TPR = TPResult::True();
125
126  assert(TPR == TPResult::True() || TPR == TPResult::False());
127  return TPR == TPResult::True();
128}
129
130/// simple-declaration:
131///   decl-specifier-seq init-declarator-list[opt] ';'
132///
133Parser::TPResult Parser::TryParseSimpleDeclaration() {
134  // We know that we have a simple-type-specifier/typename-specifier followed
135  // by a '('.
136  assert(isCXXDeclarationSpecifier() == TPResult::Ambiguous());
137
138  if (Tok.is(tok::kw_typeof))
139    TryParseTypeofSpecifier();
140  else {
141    ConsumeToken();
142
143    if (getLang().ObjC1 && Tok.is(tok::less))
144      TryParseProtocolQualifiers();
145  }
146
147  assert(Tok.is(tok::l_paren) && "Expected '('");
148
149  TPResult TPR = TryParseInitDeclaratorList();
150  if (TPR != TPResult::Ambiguous())
151    return TPR;
152
153  if (Tok.isNot(tok::semi))
154    return TPResult::False();
155
156  return TPResult::Ambiguous();
157}
158
159///       init-declarator-list:
160///         init-declarator
161///         init-declarator-list ',' init-declarator
162///
163///       init-declarator:
164///         declarator initializer[opt]
165/// [GNU]   declarator simple-asm-expr[opt] attributes[opt] initializer[opt]
166///
167/// initializer:
168///   '=' initializer-clause
169///   '(' expression-list ')'
170///
171/// initializer-clause:
172///   assignment-expression
173///   '{' initializer-list ','[opt] '}'
174///   '{' '}'
175///
176Parser::TPResult Parser::TryParseInitDeclaratorList() {
177  while (1) {
178    // declarator
179    TPResult TPR = TryParseDeclarator(false/*mayBeAbstract*/);
180    if (TPR != TPResult::Ambiguous())
181      return TPR;
182
183    // [GNU] simple-asm-expr[opt] attributes[opt]
184    if (Tok.is(tok::kw_asm) || Tok.is(tok::kw___attribute))
185      return TPResult::True();
186
187    // initializer[opt]
188    if (Tok.is(tok::l_paren)) {
189      // Parse through the parens.
190      ConsumeParen();
191      if (!SkipUntil(tok::r_paren))
192        return TPResult::Error();
193    } else if (Tok.is(tok::equal) || isTokIdentifier_in()) {
194      // MSVC and g++ won't examine the rest of declarators if '=' is
195      // encountered; they just conclude that we have a declaration.
196      // EDG parses the initializer completely, which is the proper behavior
197      // for this case.
198      //
199      // At present, Clang follows MSVC and g++, since the parser does not have
200      // the ability to parse an expression fully without recording the
201      // results of that parse.
202      // Also allow 'in' after on objective-c declaration as in:
203      // for (int (^b)(void) in array). Ideally this should be done in the
204      // context of parsing for-init-statement of a foreach statement only. But,
205      // in any other context 'in' is invalid after a declaration and parser
206      // issues the error regardless of outcome of this decision.
207      // FIXME. Change if above assumption does not hold.
208      return TPResult::True();
209    }
210
211    if (Tok.isNot(tok::comma))
212      break;
213    ConsumeToken(); // the comma.
214  }
215
216  return TPResult::Ambiguous();
217}
218
219/// isCXXConditionDeclaration - Disambiguates between a declaration or an
220/// expression for a condition of a if/switch/while/for statement.
221/// If during the disambiguation process a parsing error is encountered,
222/// the function returns true to let the declaration parsing code handle it.
223///
224///       condition:
225///         expression
226///         type-specifier-seq declarator '=' assignment-expression
227/// [GNU]   type-specifier-seq declarator simple-asm-expr[opt] attributes[opt]
228///             '=' assignment-expression
229///
230bool Parser::isCXXConditionDeclaration() {
231  TPResult TPR = isCXXDeclarationSpecifier();
232  if (TPR != TPResult::Ambiguous())
233    return TPR != TPResult::False(); // Returns true for TPResult::True() or
234                                     // TPResult::Error().
235
236  // FIXME: Add statistics about the number of ambiguous statements encountered
237  // and how they were resolved (number of declarations+number of expressions).
238
239  // Ok, we have a simple-type-specifier/typename-specifier followed by a '('.
240  // We need tentative parsing...
241
242  TentativeParsingAction PA(*this);
243
244  // type-specifier-seq
245  if (Tok.is(tok::kw_typeof))
246    TryParseTypeofSpecifier();
247  else {
248    ConsumeToken();
249
250    if (getLang().ObjC1 && Tok.is(tok::less))
251      TryParseProtocolQualifiers();
252  }
253  assert(Tok.is(tok::l_paren) && "Expected '('");
254
255  // declarator
256  TPR = TryParseDeclarator(false/*mayBeAbstract*/);
257
258  // In case of an error, let the declaration parsing code handle it.
259  if (TPR == TPResult::Error())
260    TPR = TPResult::True();
261
262  if (TPR == TPResult::Ambiguous()) {
263    // '='
264    // [GNU] simple-asm-expr[opt] attributes[opt]
265    if (Tok.is(tok::equal)  ||
266        Tok.is(tok::kw_asm) || Tok.is(tok::kw___attribute))
267      TPR = TPResult::True();
268    else
269      TPR = TPResult::False();
270  }
271
272  PA.Revert();
273
274  assert(TPR == TPResult::True() || TPR == TPResult::False());
275  return TPR == TPResult::True();
276}
277
278  /// \brief Determine whether the next set of tokens contains a type-id.
279  ///
280  /// The context parameter states what context we're parsing right
281  /// now, which affects how this routine copes with the token
282  /// following the type-id. If the context is TypeIdInParens, we have
283  /// already parsed the '(' and we will cease lookahead when we hit
284  /// the corresponding ')'. If the context is
285  /// TypeIdAsTemplateArgument, we've already parsed the '<' or ','
286  /// before this template argument, and will cease lookahead when we
287  /// hit a '>', '>>' (in C++0x), or ','. Returns true for a type-id
288  /// and false for an expression.  If during the disambiguation
289  /// process a parsing error is encountered, the function returns
290  /// true to let the declaration parsing code handle it.
291  ///
292  /// type-id:
293  ///   type-specifier-seq abstract-declarator[opt]
294  ///
295bool Parser::isCXXTypeId(TentativeCXXTypeIdContext Context, bool &isAmbiguous) {
296
297  isAmbiguous = false;
298
299  // C++ 8.2p2:
300  // The ambiguity arising from the similarity between a function-style cast and
301  // a type-id can occur in different contexts. The ambiguity appears as a
302  // choice between a function-style cast expression and a declaration of a
303  // type. The resolution is that any construct that could possibly be a type-id
304  // in its syntactic context shall be considered a type-id.
305
306  TPResult TPR = isCXXDeclarationSpecifier();
307  if (TPR != TPResult::Ambiguous())
308    return TPR != TPResult::False(); // Returns true for TPResult::True() or
309                                     // TPResult::Error().
310
311  // FIXME: Add statistics about the number of ambiguous statements encountered
312  // and how they were resolved (number of declarations+number of expressions).
313
314  // Ok, we have a simple-type-specifier/typename-specifier followed by a '('.
315  // We need tentative parsing...
316
317  TentativeParsingAction PA(*this);
318
319  // type-specifier-seq
320  if (Tok.is(tok::kw_typeof))
321    TryParseTypeofSpecifier();
322  else {
323    ConsumeToken();
324
325    if (getLang().ObjC1 && Tok.is(tok::less))
326      TryParseProtocolQualifiers();
327  }
328
329  assert(Tok.is(tok::l_paren) && "Expected '('");
330
331  // declarator
332  TPR = TryParseDeclarator(true/*mayBeAbstract*/, false/*mayHaveIdentifier*/);
333
334  // In case of an error, let the declaration parsing code handle it.
335  if (TPR == TPResult::Error())
336    TPR = TPResult::True();
337
338  if (TPR == TPResult::Ambiguous()) {
339    // We are supposed to be inside parens, so if after the abstract declarator
340    // we encounter a ')' this is a type-id, otherwise it's an expression.
341    if (Context == TypeIdInParens && Tok.is(tok::r_paren)) {
342      TPR = TPResult::True();
343      isAmbiguous = true;
344
345    // We are supposed to be inside a template argument, so if after
346    // the abstract declarator we encounter a '>', '>>' (in C++0x), or
347    // ',', this is a type-id. Otherwise, it's an expression.
348    } else if (Context == TypeIdAsTemplateArgument &&
349               (Tok.is(tok::greater) || Tok.is(tok::comma) ||
350                (getLang().CPlusPlus0x && Tok.is(tok::greatergreater)))) {
351      TPR = TPResult::True();
352      isAmbiguous = true;
353
354    } else
355      TPR = TPResult::False();
356  }
357
358  PA.Revert();
359
360  assert(TPR == TPResult::True() || TPR == TPResult::False());
361  return TPR == TPResult::True();
362}
363
364/// isCXX0XAttributeSpecifier - returns true if this is a C++0x
365/// attribute-specifier. By default, unless in Obj-C++, only a cursory check is
366/// performed that will simply return true if a [[ is seen. Currently C++ has no
367/// syntactical ambiguities from this check, but it may inhibit error recovery.
368/// If CheckClosing is true, a check is made for closing ]] brackets.
369///
370/// If given, After is set to the token after the attribute-specifier so that
371/// appropriate parsing decisions can be made; it is left untouched if false is
372/// returned.
373///
374/// FIXME: If an error is in the closing ]] brackets, the program assumes
375/// the absence of an attribute-specifier, which can cause very yucky errors
376/// to occur.
377///
378/// [C++0x] attribute-specifier:
379///         '[' '[' attribute-list ']' ']'
380///
381/// [C++0x] attribute-list:
382///         attribute[opt]
383///         attribute-list ',' attribute[opt]
384///
385/// [C++0x] attribute:
386///         attribute-token attribute-argument-clause[opt]
387///
388/// [C++0x] attribute-token:
389///         identifier
390///         attribute-scoped-token
391///
392/// [C++0x] attribute-scoped-token:
393///         attribute-namespace '::' identifier
394///
395/// [C++0x] attribute-namespace:
396///         identifier
397///
398/// [C++0x] attribute-argument-clause:
399///         '(' balanced-token-seq ')'
400///
401/// [C++0x] balanced-token-seq:
402///         balanced-token
403///         balanced-token-seq balanced-token
404///
405/// [C++0x] balanced-token:
406///         '(' balanced-token-seq ')'
407///         '[' balanced-token-seq ']'
408///         '{' balanced-token-seq '}'
409///         any token but '(', ')', '[', ']', '{', or '}'
410bool Parser::isCXX0XAttributeSpecifier (bool CheckClosing,
411                                        tok::TokenKind *After) {
412  if (Tok.isNot(tok::l_square) || NextToken().isNot(tok::l_square))
413    return false;
414
415  // No tentative parsing if we don't need to look for ]]
416  if (!CheckClosing && !getLang().ObjC1)
417    return true;
418
419  struct TentativeReverter {
420    TentativeParsingAction PA;
421
422    TentativeReverter (Parser& P)
423      : PA(P)
424    {}
425    ~TentativeReverter () {
426      PA.Revert();
427    }
428  } R(*this);
429
430  // Opening brackets were checked for above.
431  ConsumeBracket();
432  ConsumeBracket();
433
434  // SkipUntil will handle balanced tokens, which are guaranteed in attributes.
435  SkipUntil(tok::r_square, false);
436
437  if (Tok.isNot(tok::r_square))
438    return false;
439  ConsumeBracket();
440
441  if (After)
442    *After = Tok.getKind();
443
444  return true;
445}
446
447///         declarator:
448///           direct-declarator
449///           ptr-operator declarator
450///
451///         direct-declarator:
452///           declarator-id
453///           direct-declarator '(' parameter-declaration-clause ')'
454///                 cv-qualifier-seq[opt] exception-specification[opt]
455///           direct-declarator '[' constant-expression[opt] ']'
456///           '(' declarator ')'
457/// [GNU]     '(' attributes declarator ')'
458///
459///         abstract-declarator:
460///           ptr-operator abstract-declarator[opt]
461///           direct-abstract-declarator
462///           ...
463///
464///         direct-abstract-declarator:
465///           direct-abstract-declarator[opt]
466///           '(' parameter-declaration-clause ')' cv-qualifier-seq[opt]
467///                 exception-specification[opt]
468///           direct-abstract-declarator[opt] '[' constant-expression[opt] ']'
469///           '(' abstract-declarator ')'
470///
471///         ptr-operator:
472///           '*' cv-qualifier-seq[opt]
473///           '&'
474/// [C++0x]   '&&'                                                        [TODO]
475///           '::'[opt] nested-name-specifier '*' cv-qualifier-seq[opt]
476///
477///         cv-qualifier-seq:
478///           cv-qualifier cv-qualifier-seq[opt]
479///
480///         cv-qualifier:
481///           'const'
482///           'volatile'
483///
484///         declarator-id:
485///           '...'[opt] id-expression
486///
487///         id-expression:
488///           unqualified-id
489///           qualified-id                                                [TODO]
490///
491///         unqualified-id:
492///           identifier
493///           operator-function-id                                        [TODO]
494///           conversion-function-id                                      [TODO]
495///           '~' class-name                                              [TODO]
496///           template-id                                                 [TODO]
497///
498Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract,
499                                            bool mayHaveIdentifier) {
500  // declarator:
501  //   direct-declarator
502  //   ptr-operator declarator
503
504  while (1) {
505    if (Tok.is(tok::coloncolon) || Tok.is(tok::identifier))
506      if (TryAnnotateCXXScopeToken(true))
507        return TPResult::Error();
508
509    if (Tok.is(tok::star) || Tok.is(tok::amp) || Tok.is(tok::caret) ||
510        Tok.is(tok::ampamp) ||
511        (Tok.is(tok::annot_cxxscope) && NextToken().is(tok::star))) {
512      // ptr-operator
513      ConsumeToken();
514      while (Tok.is(tok::kw_const)    ||
515             Tok.is(tok::kw_volatile) ||
516             Tok.is(tok::kw_restrict))
517        ConsumeToken();
518    } else {
519      break;
520    }
521  }
522
523  // direct-declarator:
524  // direct-abstract-declarator:
525  if (Tok.is(tok::ellipsis))
526    ConsumeToken();
527
528  if ((Tok.is(tok::identifier) ||
529       (Tok.is(tok::annot_cxxscope) && NextToken().is(tok::identifier))) &&
530      mayHaveIdentifier) {
531    // declarator-id
532    if (Tok.is(tok::annot_cxxscope))
533      ConsumeToken();
534    ConsumeToken();
535  } else if (Tok.is(tok::l_paren)) {
536    ConsumeParen();
537    if (mayBeAbstract &&
538        (Tok.is(tok::r_paren) ||       // 'int()' is a function.
539         Tok.is(tok::ellipsis) ||      // 'int(...)' is a function.
540         isDeclarationSpecifier())) {   // 'int(int)' is a function.
541      // '(' parameter-declaration-clause ')' cv-qualifier-seq[opt]
542      //        exception-specification[opt]
543      TPResult TPR = TryParseFunctionDeclarator();
544      if (TPR != TPResult::Ambiguous())
545        return TPR;
546    } else {
547      // '(' declarator ')'
548      // '(' attributes declarator ')'
549      // '(' abstract-declarator ')'
550      if (Tok.is(tok::kw___attribute) ||
551          Tok.is(tok::kw___declspec) ||
552          Tok.is(tok::kw___cdecl) ||
553          Tok.is(tok::kw___stdcall) ||
554          Tok.is(tok::kw___fastcall) ||
555          Tok.is(tok::kw___thiscall))
556        return TPResult::True(); // attributes indicate declaration
557      TPResult TPR = TryParseDeclarator(mayBeAbstract, mayHaveIdentifier);
558      if (TPR != TPResult::Ambiguous())
559        return TPR;
560      if (Tok.isNot(tok::r_paren))
561        return TPResult::False();
562      ConsumeParen();
563    }
564  } else if (!mayBeAbstract) {
565    return TPResult::False();
566  }
567
568  while (1) {
569    TPResult TPR(TPResult::Ambiguous());
570
571    // abstract-declarator: ...
572    if (Tok.is(tok::ellipsis))
573      ConsumeToken();
574
575    if (Tok.is(tok::l_paren)) {
576      // Check whether we have a function declarator or a possible ctor-style
577      // initializer that follows the declarator. Note that ctor-style
578      // initializers are not possible in contexts where abstract declarators
579      // are allowed.
580      if (!mayBeAbstract && !isCXXFunctionDeclarator(false/*warnIfAmbiguous*/))
581        break;
582
583      // direct-declarator '(' parameter-declaration-clause ')'
584      //        cv-qualifier-seq[opt] exception-specification[opt]
585      ConsumeParen();
586      TPR = TryParseFunctionDeclarator();
587    } else if (Tok.is(tok::l_square)) {
588      // direct-declarator '[' constant-expression[opt] ']'
589      // direct-abstract-declarator[opt] '[' constant-expression[opt] ']'
590      TPR = TryParseBracketDeclarator();
591    } else {
592      break;
593    }
594
595    if (TPR != TPResult::Ambiguous())
596      return TPR;
597  }
598
599  return TPResult::Ambiguous();
600}
601
602Parser::TPResult
603Parser::isExpressionOrTypeSpecifierSimple(tok::TokenKind Kind) {
604  switch (Kind) {
605  // Obviously starts an expression.
606  case tok::numeric_constant:
607  case tok::char_constant:
608  case tok::string_literal:
609  case tok::wide_string_literal:
610  case tok::l_square:
611  case tok::l_paren:
612  case tok::amp:
613  case tok::ampamp:
614  case tok::star:
615  case tok::plus:
616  case tok::plusplus:
617  case tok::minus:
618  case tok::minusminus:
619  case tok::tilde:
620  case tok::exclaim:
621  case tok::kw_sizeof:
622  case tok::kw___func__:
623  case tok::kw_const_cast:
624  case tok::kw_delete:
625  case tok::kw_dynamic_cast:
626  case tok::kw_false:
627  case tok::kw_new:
628  case tok::kw_operator:
629  case tok::kw_reinterpret_cast:
630  case tok::kw_static_cast:
631  case tok::kw_this:
632  case tok::kw_throw:
633  case tok::kw_true:
634  case tok::kw_typeid:
635  case tok::kw_alignof:
636  case tok::kw_noexcept:
637  case tok::kw_nullptr:
638  case tok::kw___null:
639  case tok::kw___alignof:
640  case tok::kw___builtin_choose_expr:
641  case tok::kw___builtin_offsetof:
642  case tok::kw___builtin_types_compatible_p:
643  case tok::kw___builtin_va_arg:
644  case tok::kw___imag:
645  case tok::kw___real:
646  case tok::kw___FUNCTION__:
647  case tok::kw___PRETTY_FUNCTION__:
648  case tok::kw___has_nothrow_assign:
649  case tok::kw___has_nothrow_copy:
650  case tok::kw___has_nothrow_constructor:
651  case tok::kw___has_trivial_assign:
652  case tok::kw___has_trivial_copy:
653  case tok::kw___has_trivial_constructor:
654  case tok::kw___has_trivial_destructor:
655  case tok::kw___has_virtual_destructor:
656  case tok::kw___is_abstract:
657  case tok::kw___is_base_of:
658  case tok::kw___is_class:
659  case tok::kw___is_convertible_to:
660  case tok::kw___is_empty:
661  case tok::kw___is_enum:
662  case tok::kw___is_literal:
663  case tok::kw___is_literal_type:
664  case tok::kw___is_pod:
665  case tok::kw___is_polymorphic:
666  case tok::kw___is_trivial:
667  case tok::kw___is_trivially_copyable:
668  case tok::kw___is_union:
669  case tok::kw___uuidof:
670    return TPResult::True();
671
672  // Obviously starts a type-specifier-seq:
673  case tok::kw_char:
674  case tok::kw_const:
675  case tok::kw_double:
676  case tok::kw_enum:
677  case tok::kw_float:
678  case tok::kw_int:
679  case tok::kw_long:
680  case tok::kw___int64:
681  case tok::kw_restrict:
682  case tok::kw_short:
683  case tok::kw_signed:
684  case tok::kw_struct:
685  case tok::kw_union:
686  case tok::kw_unsigned:
687  case tok::kw_void:
688  case tok::kw_volatile:
689  case tok::kw__Bool:
690  case tok::kw__Complex:
691  case tok::kw_class:
692  case tok::kw_typename:
693  case tok::kw_wchar_t:
694  case tok::kw_char16_t:
695  case tok::kw_char32_t:
696  case tok::kw_decltype:
697  case tok::kw___underlying_type:
698  case tok::kw_thread_local:
699  case tok::kw__Decimal32:
700  case tok::kw__Decimal64:
701  case tok::kw__Decimal128:
702  case tok::kw___thread:
703  case tok::kw_typeof:
704  case tok::kw___cdecl:
705  case tok::kw___stdcall:
706  case tok::kw___fastcall:
707  case tok::kw___thiscall:
708  case tok::kw___vector:
709  case tok::kw___pixel:
710    return TPResult::False();
711
712  default:
713    break;
714  }
715
716  return TPResult::Ambiguous();
717}
718
719/// isCXXDeclarationSpecifier - Returns TPResult::True() if it is a declaration
720/// specifier, TPResult::False() if it is not, TPResult::Ambiguous() if it could
721/// be either a decl-specifier or a function-style cast, and TPResult::Error()
722/// if a parsing error was found and reported.
723///
724///         decl-specifier:
725///           storage-class-specifier
726///           type-specifier
727///           function-specifier
728///           'friend'
729///           'typedef'
730/// [C++0x]   'constexpr'
731/// [GNU]     attributes declaration-specifiers[opt]
732///
733///         storage-class-specifier:
734///           'register'
735///           'static'
736///           'extern'
737///           'mutable'
738///           'auto'
739/// [GNU]     '__thread'
740///
741///         function-specifier:
742///           'inline'
743///           'virtual'
744///           'explicit'
745///
746///         typedef-name:
747///           identifier
748///
749///         type-specifier:
750///           simple-type-specifier
751///           class-specifier
752///           enum-specifier
753///           elaborated-type-specifier
754///           typename-specifier
755///           cv-qualifier
756///
757///         simple-type-specifier:
758///           '::'[opt] nested-name-specifier[opt] type-name
759///           '::'[opt] nested-name-specifier 'template'
760///                 simple-template-id                              [TODO]
761///           'char'
762///           'wchar_t'
763///           'bool'
764///           'short'
765///           'int'
766///           'long'
767///           'signed'
768///           'unsigned'
769///           'float'
770///           'double'
771///           'void'
772/// [GNU]     typeof-specifier
773/// [GNU]     '_Complex'
774/// [C++0x]   'auto'                                                [TODO]
775/// [C++0x]   'decltype' ( expression )
776///
777///         type-name:
778///           class-name
779///           enum-name
780///           typedef-name
781///
782///         elaborated-type-specifier:
783///           class-key '::'[opt] nested-name-specifier[opt] identifier
784///           class-key '::'[opt] nested-name-specifier[opt] 'template'[opt]
785///               simple-template-id
786///           'enum' '::'[opt] nested-name-specifier[opt] identifier
787///
788///         enum-name:
789///           identifier
790///
791///         enum-specifier:
792///           'enum' identifier[opt] '{' enumerator-list[opt] '}'
793///           'enum' identifier[opt] '{' enumerator-list ',' '}'
794///
795///         class-specifier:
796///           class-head '{' member-specification[opt] '}'
797///
798///         class-head:
799///           class-key identifier[opt] base-clause[opt]
800///           class-key nested-name-specifier identifier base-clause[opt]
801///           class-key nested-name-specifier[opt] simple-template-id
802///               base-clause[opt]
803///
804///         class-key:
805///           'class'
806///           'struct'
807///           'union'
808///
809///         cv-qualifier:
810///           'const'
811///           'volatile'
812/// [GNU]     restrict
813///
814Parser::TPResult Parser::isCXXDeclarationSpecifier() {
815  switch (Tok.getKind()) {
816  case tok::identifier:   // foo::bar
817    // Check for need to substitute AltiVec __vector keyword
818    // for "vector" identifier.
819    if (TryAltiVecVectorToken())
820      return TPResult::True();
821    // Fall through.
822  case tok::kw_typename:  // typename T::type
823    // Annotate typenames and C++ scope specifiers.  If we get one, just
824    // recurse to handle whatever we get.
825    if (TryAnnotateTypeOrScopeToken())
826      return TPResult::Error();
827    if (Tok.is(tok::identifier))
828      return TPResult::False();
829    return isCXXDeclarationSpecifier();
830
831  case tok::coloncolon: {    // ::foo::bar
832    const Token &Next = NextToken();
833    if (Next.is(tok::kw_new) ||    // ::new
834        Next.is(tok::kw_delete))   // ::delete
835      return TPResult::False();
836
837    // Annotate typenames and C++ scope specifiers.  If we get one, just
838    // recurse to handle whatever we get.
839    if (TryAnnotateTypeOrScopeToken())
840      return TPResult::Error();
841    return isCXXDeclarationSpecifier();
842  }
843
844    // decl-specifier:
845    //   storage-class-specifier
846    //   type-specifier
847    //   function-specifier
848    //   'friend'
849    //   'typedef'
850    //   'constexpr'
851  case tok::kw_friend:
852  case tok::kw_typedef:
853  case tok::kw_constexpr:
854    // storage-class-specifier
855  case tok::kw_register:
856  case tok::kw_static:
857  case tok::kw_extern:
858  case tok::kw_mutable:
859  case tok::kw_auto:
860  case tok::kw___thread:
861    // function-specifier
862  case tok::kw_inline:
863  case tok::kw_virtual:
864  case tok::kw_explicit:
865
866    // type-specifier:
867    //   simple-type-specifier
868    //   class-specifier
869    //   enum-specifier
870    //   elaborated-type-specifier
871    //   typename-specifier
872    //   cv-qualifier
873
874    // class-specifier
875    // elaborated-type-specifier
876  case tok::kw_class:
877  case tok::kw_struct:
878  case tok::kw_union:
879    // enum-specifier
880  case tok::kw_enum:
881    // cv-qualifier
882  case tok::kw_const:
883  case tok::kw_volatile:
884
885    // GNU
886  case tok::kw_restrict:
887  case tok::kw__Complex:
888  case tok::kw___attribute:
889    return TPResult::True();
890
891    // Microsoft
892  case tok::kw___declspec:
893  case tok::kw___cdecl:
894  case tok::kw___stdcall:
895  case tok::kw___fastcall:
896  case tok::kw___thiscall:
897  case tok::kw___w64:
898  case tok::kw___ptr64:
899  case tok::kw___forceinline:
900    return TPResult::True();
901
902    // Borland
903  case tok::kw___pascal:
904    return TPResult::True();
905
906    // AltiVec
907  case tok::kw___vector:
908    return TPResult::True();
909
910  case tok::annot_template_id: {
911    TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
912    if (TemplateId->Kind != TNK_Type_template)
913      return TPResult::False();
914    CXXScopeSpec SS;
915    AnnotateTemplateIdTokenAsType();
916    assert(Tok.is(tok::annot_typename));
917    goto case_typename;
918  }
919
920  case tok::annot_cxxscope: // foo::bar or ::foo::bar, but already parsed
921    // We've already annotated a scope; try to annotate a type.
922    if (TryAnnotateTypeOrScopeToken())
923      return TPResult::Error();
924    if (!Tok.is(tok::annot_typename))
925      return TPResult::False();
926    // If that succeeded, fallthrough into the generic simple-type-id case.
927
928    // The ambiguity resides in a simple-type-specifier/typename-specifier
929    // followed by a '('. The '(' could either be the start of:
930    //
931    //   direct-declarator:
932    //     '(' declarator ')'
933    //
934    //   direct-abstract-declarator:
935    //     '(' parameter-declaration-clause ')' cv-qualifier-seq[opt]
936    //              exception-specification[opt]
937    //     '(' abstract-declarator ')'
938    //
939    // or part of a function-style cast expression:
940    //
941    //     simple-type-specifier '(' expression-list[opt] ')'
942    //
943
944    // simple-type-specifier:
945
946  case tok::annot_typename:
947  case_typename:
948    // In Objective-C, we might have a protocol-qualified type.
949    if (getLang().ObjC1 && NextToken().is(tok::less)) {
950      // Tentatively parse the
951      TentativeParsingAction PA(*this);
952      ConsumeToken(); // The type token
953
954      TPResult TPR = TryParseProtocolQualifiers();
955      bool isFollowedByParen = Tok.is(tok::l_paren);
956
957      PA.Revert();
958
959      if (TPR == TPResult::Error())
960        return TPResult::Error();
961
962      if (isFollowedByParen)
963        return TPResult::Ambiguous();
964
965      return TPResult::True();
966    }
967
968  case tok::kw_char:
969  case tok::kw_wchar_t:
970  case tok::kw_char16_t:
971  case tok::kw_char32_t:
972  case tok::kw_bool:
973  case tok::kw_short:
974  case tok::kw_int:
975  case tok::kw_long:
976  case tok::kw___int64:
977  case tok::kw_signed:
978  case tok::kw_unsigned:
979  case tok::kw_float:
980  case tok::kw_double:
981  case tok::kw_void:
982    if (NextToken().is(tok::l_paren))
983      return TPResult::Ambiguous();
984
985    if (isStartOfObjCClassMessageMissingOpenBracket())
986      return TPResult::False();
987
988    return TPResult::True();
989
990  // GNU typeof support.
991  case tok::kw_typeof: {
992    if (NextToken().isNot(tok::l_paren))
993      return TPResult::True();
994
995    TentativeParsingAction PA(*this);
996
997    TPResult TPR = TryParseTypeofSpecifier();
998    bool isFollowedByParen = Tok.is(tok::l_paren);
999
1000    PA.Revert();
1001
1002    if (TPR == TPResult::Error())
1003      return TPResult::Error();
1004
1005    if (isFollowedByParen)
1006      return TPResult::Ambiguous();
1007
1008    return TPResult::True();
1009  }
1010
1011  // C++0x decltype support.
1012  case tok::kw_decltype:
1013    return TPResult::True();
1014
1015  // C++0x type traits support
1016  case tok::kw___underlying_type:
1017    return TPResult::True();
1018
1019  default:
1020    return TPResult::False();
1021  }
1022}
1023
1024/// [GNU] typeof-specifier:
1025///         'typeof' '(' expressions ')'
1026///         'typeof' '(' type-name ')'
1027///
1028Parser::TPResult Parser::TryParseTypeofSpecifier() {
1029  assert(Tok.is(tok::kw_typeof) && "Expected 'typeof'!");
1030  ConsumeToken();
1031
1032  assert(Tok.is(tok::l_paren) && "Expected '('");
1033  // Parse through the parens after 'typeof'.
1034  ConsumeParen();
1035  if (!SkipUntil(tok::r_paren))
1036    return TPResult::Error();
1037
1038  return TPResult::Ambiguous();
1039}
1040
1041/// [ObjC] protocol-qualifiers:
1042////         '<' identifier-list '>'
1043Parser::TPResult Parser::TryParseProtocolQualifiers() {
1044  assert(Tok.is(tok::less) && "Expected '<' for qualifier list");
1045  ConsumeToken();
1046  do {
1047    if (Tok.isNot(tok::identifier))
1048      return TPResult::Error();
1049    ConsumeToken();
1050
1051    if (Tok.is(tok::comma)) {
1052      ConsumeToken();
1053      continue;
1054    }
1055
1056    if (Tok.is(tok::greater)) {
1057      ConsumeToken();
1058      return TPResult::Ambiguous();
1059    }
1060  } while (false);
1061
1062  return TPResult::Error();
1063}
1064
1065Parser::TPResult Parser::TryParseDeclarationSpecifier() {
1066  TPResult TPR = isCXXDeclarationSpecifier();
1067  if (TPR != TPResult::Ambiguous())
1068    return TPR;
1069
1070  if (Tok.is(tok::kw_typeof))
1071    TryParseTypeofSpecifier();
1072  else {
1073    ConsumeToken();
1074
1075    if (getLang().ObjC1 && Tok.is(tok::less))
1076      TryParseProtocolQualifiers();
1077  }
1078
1079  assert(Tok.is(tok::l_paren) && "Expected '('!");
1080  return TPResult::Ambiguous();
1081}
1082
1083/// isCXXFunctionDeclarator - Disambiguates between a function declarator or
1084/// a constructor-style initializer, when parsing declaration statements.
1085/// Returns true for function declarator and false for constructor-style
1086/// initializer.
1087/// If during the disambiguation process a parsing error is encountered,
1088/// the function returns true to let the declaration parsing code handle it.
1089///
1090/// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt]
1091///         exception-specification[opt]
1092///
1093bool Parser::isCXXFunctionDeclarator(bool warnIfAmbiguous) {
1094
1095  // C++ 8.2p1:
1096  // The ambiguity arising from the similarity between a function-style cast and
1097  // a declaration mentioned in 6.8 can also occur in the context of a
1098  // declaration. In that context, the choice is between a function declaration
1099  // with a redundant set of parentheses around a parameter name and an object
1100  // declaration with a function-style cast as the initializer. Just as for the
1101  // ambiguities mentioned in 6.8, the resolution is to consider any construct
1102  // that could possibly be a declaration a declaration.
1103
1104  TentativeParsingAction PA(*this);
1105
1106  ConsumeParen();
1107  TPResult TPR = TryParseParameterDeclarationClause();
1108  if (TPR == TPResult::Ambiguous() && Tok.isNot(tok::r_paren))
1109    TPR = TPResult::False();
1110
1111  SourceLocation TPLoc = Tok.getLocation();
1112  PA.Revert();
1113
1114  // In case of an error, let the declaration parsing code handle it.
1115  if (TPR == TPResult::Error())
1116    return true;
1117
1118  if (TPR == TPResult::Ambiguous()) {
1119    // Function declarator has precedence over constructor-style initializer.
1120    // Emit a warning just in case the author intended a variable definition.
1121    if (warnIfAmbiguous)
1122      Diag(Tok, diag::warn_parens_disambiguated_as_function_decl)
1123        << SourceRange(Tok.getLocation(), TPLoc);
1124    return true;
1125  }
1126
1127  return TPR == TPResult::True();
1128}
1129
1130/// parameter-declaration-clause:
1131///   parameter-declaration-list[opt] '...'[opt]
1132///   parameter-declaration-list ',' '...'
1133///
1134/// parameter-declaration-list:
1135///   parameter-declaration
1136///   parameter-declaration-list ',' parameter-declaration
1137///
1138/// parameter-declaration:
1139///   decl-specifier-seq declarator attributes[opt]
1140///   decl-specifier-seq declarator attributes[opt] '=' assignment-expression
1141///   decl-specifier-seq abstract-declarator[opt] attributes[opt]
1142///   decl-specifier-seq abstract-declarator[opt] attributes[opt]
1143///     '=' assignment-expression
1144///
1145Parser::TPResult Parser::TryParseParameterDeclarationClause() {
1146
1147  if (Tok.is(tok::r_paren))
1148    return TPResult::True();
1149
1150  //   parameter-declaration-list[opt] '...'[opt]
1151  //   parameter-declaration-list ',' '...'
1152  //
1153  // parameter-declaration-list:
1154  //   parameter-declaration
1155  //   parameter-declaration-list ',' parameter-declaration
1156  //
1157  while (1) {
1158    // '...'[opt]
1159    if (Tok.is(tok::ellipsis)) {
1160      ConsumeToken();
1161      return TPResult::True(); // '...' is a sign of a function declarator.
1162    }
1163
1164    ParsedAttributes attrs(AttrFactory);
1165    MaybeParseMicrosoftAttributes(attrs);
1166
1167    // decl-specifier-seq
1168    TPResult TPR = TryParseDeclarationSpecifier();
1169    if (TPR != TPResult::Ambiguous())
1170      return TPR;
1171
1172    // declarator
1173    // abstract-declarator[opt]
1174    TPR = TryParseDeclarator(true/*mayBeAbstract*/);
1175    if (TPR != TPResult::Ambiguous())
1176      return TPR;
1177
1178    // [GNU] attributes[opt]
1179    if (Tok.is(tok::kw___attribute))
1180      return TPResult::True();
1181
1182    if (Tok.is(tok::equal)) {
1183      // '=' assignment-expression
1184      // Parse through assignment-expression.
1185      tok::TokenKind StopToks[2] ={ tok::comma, tok::r_paren };
1186      if (!SkipUntil(StopToks, 2, true/*StopAtSemi*/, true/*DontConsume*/))
1187        return TPResult::Error();
1188    }
1189
1190    if (Tok.is(tok::ellipsis)) {
1191      ConsumeToken();
1192      return TPResult::True(); // '...' is a sign of a function declarator.
1193    }
1194
1195    if (Tok.isNot(tok::comma))
1196      break;
1197    ConsumeToken(); // the comma.
1198  }
1199
1200  return TPResult::Ambiguous();
1201}
1202
1203/// TryParseFunctionDeclarator - We parsed a '(' and we want to try to continue
1204/// parsing as a function declarator.
1205/// If TryParseFunctionDeclarator fully parsed the function declarator, it will
1206/// return TPResult::Ambiguous(), otherwise it will return either False() or
1207/// Error().
1208///
1209/// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt]
1210///         exception-specification[opt]
1211///
1212/// exception-specification:
1213///   'throw' '(' type-id-list[opt] ')'
1214///
1215Parser::TPResult Parser::TryParseFunctionDeclarator() {
1216
1217  // The '(' is already parsed.
1218
1219  TPResult TPR = TryParseParameterDeclarationClause();
1220  if (TPR == TPResult::Ambiguous() && Tok.isNot(tok::r_paren))
1221    TPR = TPResult::False();
1222
1223  if (TPR == TPResult::False() || TPR == TPResult::Error())
1224    return TPR;
1225
1226  // Parse through the parens.
1227  if (!SkipUntil(tok::r_paren))
1228    return TPResult::Error();
1229
1230  // cv-qualifier-seq
1231  while (Tok.is(tok::kw_const)    ||
1232         Tok.is(tok::kw_volatile) ||
1233         Tok.is(tok::kw_restrict)   )
1234    ConsumeToken();
1235
1236  // ref-qualifier[opt]
1237  if (Tok.is(tok::amp) || Tok.is(tok::ampamp))
1238    ConsumeToken();
1239
1240  // exception-specification
1241  if (Tok.is(tok::kw_throw)) {
1242    ConsumeToken();
1243    if (Tok.isNot(tok::l_paren))
1244      return TPResult::Error();
1245
1246    // Parse through the parens after 'throw'.
1247    ConsumeParen();
1248    if (!SkipUntil(tok::r_paren))
1249      return TPResult::Error();
1250  }
1251  if (Tok.is(tok::kw_noexcept)) {
1252    ConsumeToken();
1253    // Possibly an expression as well.
1254    if (Tok.is(tok::l_paren)) {
1255      // Find the matching rparen.
1256      ConsumeParen();
1257      if (!SkipUntil(tok::r_paren))
1258        return TPResult::Error();
1259    }
1260  }
1261
1262  return TPResult::Ambiguous();
1263}
1264
1265/// '[' constant-expression[opt] ']'
1266///
1267Parser::TPResult Parser::TryParseBracketDeclarator() {
1268  ConsumeBracket();
1269  if (!SkipUntil(tok::r_square))
1270    return TPResult::Error();
1271
1272  return TPResult::Ambiguous();
1273}
1274