ParseExpr.cpp revision 59232d35f5820e334b6c8b007ae8006f4390055d 
1//===--- ParseExpr.cpp - Expression 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 Expression parsing implementation.  Expressions in
11// C99 basically consist of a bunch of binary operators with unary operators and
12// other random stuff at the leaves.
13//
14// In the C99 grammar, these unary operators bind tightest and are represented
15// as the 'cast-expression' production.  Everything else is either a binary
16// operator (e.g. '/') or a ternary operator ("?:").  The unary leaves are
17// handled by ParseCastExpression, the higher level pieces are handled by
18// ParseBinaryExpression.
19//
20//===----------------------------------------------------------------------===//
21
22#include "clang/Parse/Parser.h"
23#include "clang/Parse/DeclSpec.h"
24#include "clang/Parse/Scope.h"
25#include "ExtensionRAIIObject.h"
26#include "AstGuard.h"
27#include "llvm/ADT/SmallVector.h"
28#include "llvm/ADT/SmallString.h"
29using namespace clang;
30
31/// PrecedenceLevels - These are precedences for the binary/ternary operators in
32/// the C99 grammar.  These have been named to relate with the C99 grammar
33/// productions.  Low precedences numbers bind more weakly than high numbers.
34namespace prec {
35  enum Level {
36    Unknown        = 0,    // Not binary operator.
37    Comma          = 1,    // ,
38    Assignment     = 2,    // =, *=, /=, %=, +=, -=, <<=, >>=, &=, ^=, |=
39    Conditional    = 3,    // ?
40    LogicalOr      = 4,    // ||
41    LogicalAnd     = 5,    // &&
42    InclusiveOr    = 6,    // |
43    ExclusiveOr    = 7,    // ^
44    And            = 8,    // &
45    Equality       = 9,    // ==, !=
46    Relational     = 10,   //  >=, <=, >, <
47    Shift          = 11,   // <<, >>
48    Additive       = 12,   // -, +
49    Multiplicative = 13    // *, /, %
50  };
51}
52
53
54/// getBinOpPrecedence - Return the precedence of the specified binary operator
55/// token.  This returns:
56///
57static prec::Level getBinOpPrecedence(tok::TokenKind Kind) {
58  switch (Kind) {
59  default:                        return prec::Unknown;
60  case tok::comma:                return prec::Comma;
61  case tok::equal:
62  case tok::starequal:
63  case tok::slashequal:
64  case tok::percentequal:
65  case tok::plusequal:
66  case tok::minusequal:
67  case tok::lesslessequal:
68  case tok::greatergreaterequal:
69  case tok::ampequal:
70  case tok::caretequal:
71  case tok::pipeequal:            return prec::Assignment;
72  case tok::question:             return prec::Conditional;
73  case tok::pipepipe:             return prec::LogicalOr;
74  case tok::ampamp:               return prec::LogicalAnd;
75  case tok::pipe:                 return prec::InclusiveOr;
76  case tok::caret:                return prec::ExclusiveOr;
77  case tok::amp:                  return prec::And;
78  case tok::exclaimequal:
79  case tok::equalequal:           return prec::Equality;
80  case tok::lessequal:
81  case tok::less:
82  case tok::greaterequal:
83  case tok::greater:              return prec::Relational;
84  case tok::lessless:
85  case tok::greatergreater:       return prec::Shift;
86  case tok::plus:
87  case tok::minus:                return prec::Additive;
88  case tok::percent:
89  case tok::slash:
90  case tok::star:                 return prec::Multiplicative;
91  }
92}
93
94
95/// ParseExpression - Simple precedence-based parser for binary/ternary
96/// operators.
97///
98/// Note: we diverge from the C99 grammar when parsing the assignment-expression
99/// production.  C99 specifies that the LHS of an assignment operator should be
100/// parsed as a unary-expression, but consistency dictates that it be a
101/// conditional-expession.  In practice, the important thing here is that the
102/// LHS of an assignment has to be an l-value, which productions between
103/// unary-expression and conditional-expression don't produce.  Because we want
104/// consistency, we parse the LHS as a conditional-expression, then check for
105/// l-value-ness in semantic analysis stages.
106///
107///       multiplicative-expression: [C99 6.5.5]
108///         cast-expression
109///         multiplicative-expression '*' cast-expression
110///         multiplicative-expression '/' cast-expression
111///         multiplicative-expression '%' cast-expression
112///
113///       additive-expression: [C99 6.5.6]
114///         multiplicative-expression
115///         additive-expression '+' multiplicative-expression
116///         additive-expression '-' multiplicative-expression
117///
118///       shift-expression: [C99 6.5.7]
119///         additive-expression
120///         shift-expression '<<' additive-expression
121///         shift-expression '>>' additive-expression
122///
123///       relational-expression: [C99 6.5.8]
124///         shift-expression
125///         relational-expression '<' shift-expression
126///         relational-expression '>' shift-expression
127///         relational-expression '<=' shift-expression
128///         relational-expression '>=' shift-expression
129///
130///       equality-expression: [C99 6.5.9]
131///         relational-expression
132///         equality-expression '==' relational-expression
133///         equality-expression '!=' relational-expression
134///
135///       AND-expression: [C99 6.5.10]
136///         equality-expression
137///         AND-expression '&' equality-expression
138///
139///       exclusive-OR-expression: [C99 6.5.11]
140///         AND-expression
141///         exclusive-OR-expression '^' AND-expression
142///
143///       inclusive-OR-expression: [C99 6.5.12]
144///         exclusive-OR-expression
145///         inclusive-OR-expression '|' exclusive-OR-expression
146///
147///       logical-AND-expression: [C99 6.5.13]
148///         inclusive-OR-expression
149///         logical-AND-expression '&&' inclusive-OR-expression
150///
151///       logical-OR-expression: [C99 6.5.14]
152///         logical-AND-expression
153///         logical-OR-expression '||' logical-AND-expression
154///
155///       conditional-expression: [C99 6.5.15]
156///         logical-OR-expression
157///         logical-OR-expression '?' expression ':' conditional-expression
158/// [GNU]   logical-OR-expression '?' ':' conditional-expression
159///
160///       assignment-expression: [C99 6.5.16]
161///         conditional-expression
162///         unary-expression assignment-operator assignment-expression
163/// [C++]   throw-expression [C++ 15]
164///
165///       assignment-operator: one of
166///         = *= /= %= += -= <<= >>= &= ^= |=
167///
168///       expression: [C99 6.5.17]
169///         assignment-expression
170///         expression ',' assignment-expression
171///
172Parser::OwningExprResult Parser::ParseExpression() {
173  if (Tok.is(tok::kw_throw))
174    return ParseThrowExpression();
175
176  OwningExprResult LHS(ParseCastExpression(false));
177  if (LHS.isInvalid()) return move(LHS);
178
179  return ParseRHSOfBinaryExpression(move(LHS), prec::Comma);
180}
181
182/// This routine is called when the '@' is seen and consumed.
183/// Current token is an Identifier and is not a 'try'. This
184/// routine is necessary to disambiguate @try-statement from,
185/// for example, @encode-expression.
186///
187Parser::OwningExprResult
188Parser::ParseExpressionWithLeadingAt(SourceLocation AtLoc) {
189  OwningExprResult LHS(ParseObjCAtExpression(AtLoc));
190  if (LHS.isInvalid()) return move(LHS);
191
192  return ParseRHSOfBinaryExpression(move(LHS), prec::Comma);
193}
194
195/// ParseAssignmentExpression - Parse an expr that doesn't include commas.
196///
197Parser::OwningExprResult Parser::ParseAssignmentExpression() {
198  if (Tok.is(tok::kw_throw))
199    return ParseThrowExpression();
200
201  OwningExprResult LHS(ParseCastExpression(false));
202  if (LHS.isInvalid()) return move(LHS);
203
204  return ParseRHSOfBinaryExpression(move(LHS), prec::Assignment);
205}
206
207/// ParseAssignmentExprWithObjCMessageExprStart - Parse an assignment expression
208/// where part of an objc message send has already been parsed.  In this case
209/// LBracLoc indicates the location of the '[' of the message send, and either
210/// ReceiverName or ReceiverExpr is non-null indicating the receiver of the
211/// message.
212///
213/// Since this handles full assignment-expression's, it handles postfix
214/// expressions and other binary operators for these expressions as well.
215Parser::OwningExprResult
216Parser::ParseAssignmentExprWithObjCMessageExprStart(SourceLocation LBracLoc,
217                                                    SourceLocation NameLoc,
218                                                   IdentifierInfo *ReceiverName,
219                                                    ExprArg ReceiverExpr) {
220  OwningExprResult R(ParseObjCMessageExpressionBody(LBracLoc, NameLoc,
221                                                    ReceiverName,
222                                                    move(ReceiverExpr)));
223  if (R.isInvalid()) return move(R);
224  R = ParsePostfixExpressionSuffix(move(R));
225  if (R.isInvalid()) return move(R);
226  return ParseRHSOfBinaryExpression(move(R), prec::Assignment);
227}
228
229
230Parser::OwningExprResult Parser::ParseConstantExpression() {
231  OwningExprResult LHS(ParseCastExpression(false));
232  if (LHS.isInvalid()) return move(LHS);
233
234  return ParseRHSOfBinaryExpression(move(LHS), prec::Conditional);
235}
236
237/// ParseRHSOfBinaryExpression - Parse a binary expression that starts with
238/// LHS and has a precedence of at least MinPrec.
239Parser::OwningExprResult
240Parser::ParseRHSOfBinaryExpression(OwningExprResult LHS, unsigned MinPrec) {
241  unsigned NextTokPrec = getBinOpPrecedence(Tok.getKind());
242  SourceLocation ColonLoc;
243
244  while (1) {
245    // If this token has a lower precedence than we are allowed to parse (e.g.
246    // because we are called recursively, or because the token is not a binop),
247    // then we are done!
248    if (NextTokPrec < MinPrec)
249      return move(LHS);
250
251    // Consume the operator, saving the operator token for error reporting.
252    Token OpToken = Tok;
253    ConsumeToken();
254
255    // Special case handling for the ternary operator.
256    OwningExprResult TernaryMiddle(Actions, true);
257    if (NextTokPrec == prec::Conditional) {
258      if (Tok.isNot(tok::colon)) {
259        // Handle this production specially:
260        //   logical-OR-expression '?' expression ':' conditional-expression
261        // In particular, the RHS of the '?' is 'expression', not
262        // 'logical-OR-expression' as we might expect.
263        TernaryMiddle = ParseExpression();
264        if (TernaryMiddle.isInvalid())
265          return move(TernaryMiddle);
266      } else {
267        // Special case handling of "X ? Y : Z" where Y is empty:
268        //   logical-OR-expression '?' ':' conditional-expression   [GNU]
269        TernaryMiddle = 0;
270        Diag(Tok, diag::ext_gnu_conditional_expr);
271      }
272
273      if (Tok.isNot(tok::colon)) {
274        Diag(Tok, diag::err_expected_colon);
275        Diag(OpToken, diag::note_matching) << "?";
276        return ExprError();
277      }
278
279      // Eat the colon.
280      ColonLoc = ConsumeToken();
281    }
282
283    // Parse another leaf here for the RHS of the operator.
284    OwningExprResult RHS(ParseCastExpression(false));
285    if (RHS.isInvalid())
286      return move(RHS);
287
288    // Remember the precedence of this operator and get the precedence of the
289    // operator immediately to the right of the RHS.
290    unsigned ThisPrec = NextTokPrec;
291    NextTokPrec = getBinOpPrecedence(Tok.getKind());
292
293    // Assignment and conditional expressions are right-associative.
294    bool isRightAssoc = ThisPrec == prec::Conditional ||
295                        ThisPrec == prec::Assignment;
296
297    // Get the precedence of the operator to the right of the RHS.  If it binds
298    // more tightly with RHS than we do, evaluate it completely first.
299    if (ThisPrec < NextTokPrec ||
300        (ThisPrec == NextTokPrec && isRightAssoc)) {
301      // If this is left-associative, only parse things on the RHS that bind
302      // more tightly than the current operator.  If it is left-associative, it
303      // is okay, to bind exactly as tightly.  For example, compile A=B=C=D as
304      // A=(B=(C=D)), where each paren is a level of recursion here.
305      // The function takes ownership of the RHS.
306      RHS = ParseRHSOfBinaryExpression(move(RHS), ThisPrec + !isRightAssoc);
307      if (RHS.isInvalid())
308        return move(RHS);
309
310      NextTokPrec = getBinOpPrecedence(Tok.getKind());
311    }
312    assert(NextTokPrec <= ThisPrec && "Recursion didn't work!");
313
314    if (!LHS.isInvalid()) {
315      // Combine the LHS and RHS into the LHS (e.g. build AST).
316      if (TernaryMiddle.isInvalid())
317        LHS = Actions.ActOnBinOp(CurScope, OpToken.getLocation(),
318                                 OpToken.getKind(), LHS.release(),
319                                 RHS.release());
320      else
321        LHS = Actions.ActOnConditionalOp(OpToken.getLocation(), ColonLoc,
322                                         LHS.release(), TernaryMiddle.release(),
323                                         RHS.release());
324    }
325  }
326}
327
328/// ParseCastExpression - Parse a cast-expression, or, if isUnaryExpression is
329/// true, parse a unary-expression.
330///
331///       cast-expression: [C99 6.5.4]
332///         unary-expression
333///         '(' type-name ')' cast-expression
334///
335///       unary-expression:  [C99 6.5.3]
336///         postfix-expression
337///         '++' unary-expression
338///         '--' unary-expression
339///         unary-operator cast-expression
340///         'sizeof' unary-expression
341///         'sizeof' '(' type-name ')'
342/// [GNU]   '__alignof' unary-expression
343/// [GNU]   '__alignof' '(' type-name ')'
344/// [C++0x] 'alignof' '(' type-id ')'
345/// [GNU]   '&&' identifier
346/// [C++]   new-expression
347/// [C++]   delete-expression
348///
349///       unary-operator: one of
350///         '&'  '*'  '+'  '-'  '~'  '!'
351/// [GNU]   '__extension__'  '__real'  '__imag'
352///
353///       primary-expression: [C99 6.5.1]
354/// [C99]   identifier
355/// [C++]   id-expression
356///         constant
357///         string-literal
358/// [C++]   boolean-literal  [C++ 2.13.5]
359///         '(' expression ')'
360///         '__func__'        [C99 6.4.2.2]
361/// [GNU]   '__FUNCTION__'
362/// [GNU]   '__PRETTY_FUNCTION__'
363/// [GNU]   '(' compound-statement ')'
364/// [GNU]   '__builtin_va_arg' '(' assignment-expression ',' type-name ')'
365/// [GNU]   '__builtin_offsetof' '(' type-name ',' offsetof-member-designator')'
366/// [GNU]   '__builtin_choose_expr' '(' assign-expr ',' assign-expr ','
367///                                     assign-expr ')'
368/// [GNU]   '__builtin_types_compatible_p' '(' type-name ',' type-name ')'
369/// [GNU]   '__null'
370/// [OBJC]  '[' objc-message-expr ']'
371/// [OBJC]  '@selector' '(' objc-selector-arg ')'
372/// [OBJC]  '@protocol' '(' identifier ')'
373/// [OBJC]  '@encode' '(' type-name ')'
374/// [OBJC]  objc-string-literal
375/// [C++]   simple-type-specifier '(' expression-list[opt] ')'      [C++ 5.2.3]
376/// [C++]   typename-specifier '(' expression-list[opt] ')'         [TODO]
377/// [C++]   'const_cast' '<' type-name '>' '(' expression ')'       [C++ 5.2p1]
378/// [C++]   'dynamic_cast' '<' type-name '>' '(' expression ')'     [C++ 5.2p1]
379/// [C++]   'reinterpret_cast' '<' type-name '>' '(' expression ')' [C++ 5.2p1]
380/// [C++]   'static_cast' '<' type-name '>' '(' expression ')'      [C++ 5.2p1]
381/// [C++]   'typeid' '(' expression ')'                             [C++ 5.2p1]
382/// [C++]   'typeid' '(' type-id ')'                                [C++ 5.2p1]
383/// [C++]   'this'          [C++ 9.3.2]
384/// [clang] '^' block-literal
385///
386///       constant: [C99 6.4.4]
387///         integer-constant
388///         floating-constant
389///         enumeration-constant -> identifier
390///         character-constant
391///
392///       id-expression: [C++ 5.1]
393///                   unqualified-id
394///                   qualified-id           [TODO]
395///
396///       unqualified-id: [C++ 5.1]
397///                   identifier
398///                   operator-function-id
399///                   conversion-function-id [TODO]
400///                   '~' class-name         [TODO]
401///                   template-id            [TODO]
402///
403///       new-expression: [C++ 5.3.4]
404///                   '::'[opt] 'new' new-placement[opt] new-type-id
405///                                     new-initializer[opt]
406///                   '::'[opt] 'new' new-placement[opt] '(' type-id ')'
407///                                     new-initializer[opt]
408///
409///       delete-expression: [C++ 5.3.5]
410///                   '::'[opt] 'delete' cast-expression
411///                   '::'[opt] 'delete' '[' ']' cast-expression
412///
413Parser::OwningExprResult Parser::ParseCastExpression(bool isUnaryExpression) {
414  if (getLang().CPlusPlus) {
415    // Annotate typenames and C++ scope specifiers.
416    // Used only in C++, where the typename can be considered as a functional
417    // style cast ("int(1)").
418    // In C we don't expect identifiers to be treated as typenames; if it's a
419    // typedef name, let it be handled as an identifier and
420    // Actions.ActOnIdentifierExpr will emit the proper diagnostic.
421    TryAnnotateTypeOrScopeToken();
422  }
423
424  OwningExprResult Res(Actions);
425  tok::TokenKind SavedKind = Tok.getKind();
426
427  // This handles all of cast-expression, unary-expression, postfix-expression,
428  // and primary-expression.  We handle them together like this for efficiency
429  // and to simplify handling of an expression starting with a '(' token: which
430  // may be one of a parenthesized expression, cast-expression, compound literal
431  // expression, or statement expression.
432  //
433  // If the parsed tokens consist of a primary-expression, the cases below
434  // call ParsePostfixExpressionSuffix to handle the postfix expression
435  // suffixes.  Cases that cannot be followed by postfix exprs should
436  // return without invoking ParsePostfixExpressionSuffix.
437  switch (SavedKind) {
438  case tok::l_paren: {
439    // If this expression is limited to being a unary-expression, the parent can
440    // not start a cast expression.
441    ParenParseOption ParenExprType =
442      isUnaryExpression ? CompoundLiteral : CastExpr;
443    TypeTy *CastTy;
444    SourceLocation LParenLoc = Tok.getLocation();
445    SourceLocation RParenLoc;
446    Res = ParseParenExpression(ParenExprType, CastTy, RParenLoc);
447    if (Res.isInvalid()) return move(Res);
448
449    switch (ParenExprType) {
450    case SimpleExpr:   break;    // Nothing else to do.
451    case CompoundStmt: break;  // Nothing else to do.
452    case CompoundLiteral:
453      // We parsed '(' type-name ')' '{' ... '}'.  If any suffixes of
454      // postfix-expression exist, parse them now.
455      break;
456    case CastExpr:
457      // We parsed '(' type-name ')' and the thing after it wasn't a '{'.  Parse
458      // the cast-expression that follows it next.
459      // TODO: For cast expression with CastTy.
460      Res = ParseCastExpression(false);
461      if (!Res.isInvalid())
462        Res = Actions.ActOnCastExpr(LParenLoc, CastTy, RParenLoc,
463                                    Res.release());
464      return move(Res);
465    }
466
467    // These can be followed by postfix-expr pieces.
468    return ParsePostfixExpressionSuffix(move(Res));
469  }
470
471    // primary-expression
472  case tok::numeric_constant:
473    // constant: integer-constant
474    // constant: floating-constant
475
476    Res = Actions.ActOnNumericConstant(Tok);
477    ConsumeToken();
478
479    // These can be followed by postfix-expr pieces.
480    return ParsePostfixExpressionSuffix(move(Res));
481
482  case tok::kw_true:
483  case tok::kw_false:
484    return ParseCXXBoolLiteral();
485
486  case tok::identifier: {      // primary-expression: identifier
487                               // unqualified-id: identifier
488                               // constant: enumeration-constant
489
490    // Consume the identifier so that we can see if it is followed by a '('.
491    // Function designators are allowed to be undeclared (C99 6.5.1p2), so we
492    // need to know whether or not this identifier is a function designator or
493    // not.
494    IdentifierInfo &II = *Tok.getIdentifierInfo();
495    SourceLocation L = ConsumeToken();
496    Res = Actions.ActOnIdentifierExpr(CurScope, L, II, Tok.is(tok::l_paren));
497    // These can be followed by postfix-expr pieces.
498    return ParsePostfixExpressionSuffix(move(Res));
499  }
500  case tok::char_constant:     // constant: character-constant
501    Res = Actions.ActOnCharacterConstant(Tok);
502    ConsumeToken();
503    // These can be followed by postfix-expr pieces.
504    return ParsePostfixExpressionSuffix(move(Res));
505  case tok::kw___func__:       // primary-expression: __func__ [C99 6.4.2.2]
506  case tok::kw___FUNCTION__:   // primary-expression: __FUNCTION__ [GNU]
507  case tok::kw___PRETTY_FUNCTION__:  // primary-expression: __P..Y_F..N__ [GNU]
508    Res = Actions.ActOnPredefinedExpr(Tok.getLocation(), SavedKind);
509    ConsumeToken();
510    // These can be followed by postfix-expr pieces.
511    return ParsePostfixExpressionSuffix(move(Res));
512  case tok::string_literal:    // primary-expression: string-literal
513  case tok::wide_string_literal:
514    Res = ParseStringLiteralExpression();
515    if (Res.isInvalid()) return move(Res);
516    // This can be followed by postfix-expr pieces (e.g. "foo"[1]).
517    return ParsePostfixExpressionSuffix(move(Res));
518  case tok::kw___builtin_va_arg:
519  case tok::kw___builtin_offsetof:
520  case tok::kw___builtin_choose_expr:
521  case tok::kw___builtin_overload:
522  case tok::kw___builtin_types_compatible_p:
523    return ParseBuiltinPrimaryExpression();
524  case tok::kw___null:
525    return Owned(Actions.ActOnGNUNullExpr(ConsumeToken()));
526    break;
527  case tok::plusplus:      // unary-expression: '++' unary-expression
528  case tok::minusminus: {  // unary-expression: '--' unary-expression
529    SourceLocation SavedLoc = ConsumeToken();
530    Res = ParseCastExpression(true);
531    if (!Res.isInvalid())
532      Res = Owned(Actions.ActOnUnaryOp(CurScope, SavedLoc, SavedKind,
533                                       Res.release()));
534    return move(Res);
535  }
536  case tok::amp:           // unary-expression: '&' cast-expression
537  case tok::star:          // unary-expression: '*' cast-expression
538  case tok::plus:          // unary-expression: '+' cast-expression
539  case tok::minus:         // unary-expression: '-' cast-expression
540  case tok::tilde:         // unary-expression: '~' cast-expression
541  case tok::exclaim:       // unary-expression: '!' cast-expression
542  case tok::kw___real:     // unary-expression: '__real' cast-expression [GNU]
543  case tok::kw___imag: {   // unary-expression: '__imag' cast-expression [GNU]
544    SourceLocation SavedLoc = ConsumeToken();
545    Res = ParseCastExpression(false);
546    if (!Res.isInvalid())
547      Res = Actions.ActOnUnaryOp(CurScope, SavedLoc, SavedKind, Res.release());
548    return move(Res);
549  }
550
551  case tok::kw___extension__:{//unary-expression:'__extension__' cast-expr [GNU]
552    // __extension__ silences extension warnings in the subexpression.
553    ExtensionRAIIObject O(Diags);  // Use RAII to do this.
554    SourceLocation SavedLoc = ConsumeToken();
555    Res = ParseCastExpression(false);
556    if (!Res.isInvalid())
557      Res = Actions.ActOnUnaryOp(CurScope, SavedLoc, SavedKind, Res.release());
558    return move(Res);
559  }
560  case tok::kw_sizeof:     // unary-expression: 'sizeof' unary-expression
561                           // unary-expression: 'sizeof' '(' type-name ')'
562  case tok::kw_alignof:
563  case tok::kw___alignof:  // unary-expression: '__alignof' unary-expression
564                           // unary-expression: '__alignof' '(' type-name ')'
565                           // unary-expression: 'alignof' '(' type-id ')'
566    return ParseSizeofAlignofExpression();
567  case tok::ampamp: {      // unary-expression: '&&' identifier
568    SourceLocation AmpAmpLoc = ConsumeToken();
569    if (Tok.isNot(tok::identifier))
570      return ExprError(Diag(Tok, diag::err_expected_ident));
571
572    Diag(AmpAmpLoc, diag::ext_gnu_address_of_label);
573    Res = Actions.ActOnAddrLabel(AmpAmpLoc, Tok.getLocation(),
574                                 Tok.getIdentifierInfo());
575    ConsumeToken();
576    return move(Res);
577  }
578  case tok::kw_const_cast:
579  case tok::kw_dynamic_cast:
580  case tok::kw_reinterpret_cast:
581  case tok::kw_static_cast:
582    Res = ParseCXXCasts();
583    // These can be followed by postfix-expr pieces.
584    return ParsePostfixExpressionSuffix(move(Res));
585  case tok::kw_typeid:
586    Res = ParseCXXTypeid();
587    // This can be followed by postfix-expr pieces.
588    return ParsePostfixExpressionSuffix(move(Res));
589  case tok::kw_this:
590    Res = ParseCXXThis();
591    // This can be followed by postfix-expr pieces.
592    return ParsePostfixExpressionSuffix(move(Res));
593
594  case tok::kw_char:
595  case tok::kw_wchar_t:
596  case tok::kw_bool:
597  case tok::kw_short:
598  case tok::kw_int:
599  case tok::kw_long:
600  case tok::kw_signed:
601  case tok::kw_unsigned:
602  case tok::kw_float:
603  case tok::kw_double:
604  case tok::kw_void:
605  case tok::kw_typeof: {
606    if (!getLang().CPlusPlus)
607      goto UnhandledToken;
608  case tok::annot_qualtypename:
609    assert(getLang().CPlusPlus && "Expected C++");
610    // postfix-expression: simple-type-specifier '(' expression-list[opt] ')'
611    //
612    DeclSpec DS;
613    ParseCXXSimpleTypeSpecifier(DS);
614    if (Tok.isNot(tok::l_paren))
615      return ExprError(Diag(Tok, diag::err_expected_lparen_after_type)
616                         << DS.getSourceRange());
617
618    Res = ParseCXXTypeConstructExpression(DS);
619    // This can be followed by postfix-expr pieces.
620    return ParsePostfixExpressionSuffix(move(Res));
621  }
622
623  case tok::annot_cxxscope: // [C++] id-expression: qualified-id
624  case tok::kw_operator: // [C++] id-expression: operator/conversion-function-id
625                         //                      template-id
626    Res = ParseCXXIdExpression();
627    return ParsePostfixExpressionSuffix(move(Res));
628
629  case tok::coloncolon: { // [C++] new-expression or [C++] delete-expression
630    SourceLocation ScopeLoc = ConsumeToken();
631    if (Tok.is(tok::kw_new))
632      return ParseCXXNewExpression(true, ScopeLoc);
633    else {
634      // If the next token is neither 'new' nor 'delete', the :: would have been
635      // parsed as a scope specifier already.
636      assert(Tok.is(tok::kw_delete));
637      return ParseCXXDeleteExpression(true, ScopeLoc);
638    }
639  }
640
641  case tok::kw_new: // [C++] new-expression
642    return ParseCXXNewExpression(false, Tok.getLocation());
643
644  case tok::kw_delete: // [C++] delete-expression
645    return ParseCXXDeleteExpression(false, Tok.getLocation());
646
647  case tok::at: {
648    SourceLocation AtLoc = ConsumeToken();
649    return ParseObjCAtExpression(AtLoc);
650  }
651  case tok::caret:
652    if (getLang().Blocks)
653      return ParsePostfixExpressionSuffix(ParseBlockLiteralExpression());
654    Diag(Tok, diag::err_expected_expression);
655    return ExprError();
656  case tok::l_square:
657    // These can be followed by postfix-expr pieces.
658    if (getLang().ObjC1)
659      return ParsePostfixExpressionSuffix(ParseObjCMessageExpression());
660    // FALL THROUGH.
661  default:
662  UnhandledToken:
663    Diag(Tok, diag::err_expected_expression);
664    return ExprError();
665  }
666
667  // unreachable.
668  abort();
669}
670
671/// ParsePostfixExpressionSuffix - Once the leading part of a postfix-expression
672/// is parsed, this method parses any suffixes that apply.
673///
674///       postfix-expression: [C99 6.5.2]
675///         primary-expression
676///         postfix-expression '[' expression ']'
677///         postfix-expression '(' argument-expression-list[opt] ')'
678///         postfix-expression '.' identifier
679///         postfix-expression '->' identifier
680///         postfix-expression '++'
681///         postfix-expression '--'
682///         '(' type-name ')' '{' initializer-list '}'
683///         '(' type-name ')' '{' initializer-list ',' '}'
684///
685///       argument-expression-list: [C99 6.5.2]
686///         argument-expression
687///         argument-expression-list ',' assignment-expression
688///
689Parser::OwningExprResult
690Parser::ParsePostfixExpressionSuffix(OwningExprResult LHS) {
691  // Now that the primary-expression piece of the postfix-expression has been
692  // parsed, see if there are any postfix-expression pieces here.
693  SourceLocation Loc;
694  while (1) {
695    switch (Tok.getKind()) {
696    default:  // Not a postfix-expression suffix.
697      return move(LHS);
698    case tok::l_square: {  // postfix-expression: p-e '[' expression ']'
699      Loc = ConsumeBracket();
700      OwningExprResult Idx(ParseExpression());
701
702      SourceLocation RLoc = Tok.getLocation();
703
704      if (!LHS.isInvalid() && !Idx.isInvalid() && Tok.is(tok::r_square)) {
705        LHS = Actions.ActOnArraySubscriptExpr(CurScope, LHS.release(), Loc,
706                                              Idx.release(), RLoc);
707      } else
708        LHS = ExprError();
709
710      // Match the ']'.
711      MatchRHSPunctuation(tok::r_square, Loc);
712      break;
713    }
714
715    case tok::l_paren: {   // p-e: p-e '(' argument-expression-list[opt] ')'
716      ExprVector ArgExprs(Actions);
717      CommaLocsTy CommaLocs;
718
719      Loc = ConsumeParen();
720
721      if (Tok.isNot(tok::r_paren)) {
722        if (ParseExpressionList(ArgExprs, CommaLocs)) {
723          SkipUntil(tok::r_paren);
724          return ExprError();
725        }
726      }
727
728      // Match the ')'.
729      if (!LHS.isInvalid() && Tok.is(tok::r_paren)) {
730        assert((ArgExprs.size() == 0 || ArgExprs.size()-1 == CommaLocs.size())&&
731               "Unexpected number of commas!");
732        LHS = Actions.ActOnCallExpr(CurScope, LHS.release(), Loc,
733                                    ArgExprs.take(),
734                                    ArgExprs.size(), &CommaLocs[0],
735                                    Tok.getLocation());
736      }
737
738      MatchRHSPunctuation(tok::r_paren, Loc);
739      break;
740    }
741    case tok::arrow:       // postfix-expression: p-e '->' identifier
742    case tok::period: {    // postfix-expression: p-e '.' identifier
743      tok::TokenKind OpKind = Tok.getKind();
744      SourceLocation OpLoc = ConsumeToken();  // Eat the "." or "->" token.
745
746      if (Tok.isNot(tok::identifier)) {
747        Diag(Tok, diag::err_expected_ident);
748        return ExprError();
749      }
750
751      if (!LHS.isInvalid()) {
752        LHS = Actions.ActOnMemberReferenceExpr(CurScope, LHS.release(), OpLoc,
753                                               OpKind, Tok.getLocation(),
754                                               *Tok.getIdentifierInfo());
755      }
756      ConsumeToken();
757      break;
758    }
759    case tok::plusplus:    // postfix-expression: postfix-expression '++'
760    case tok::minusminus:  // postfix-expression: postfix-expression '--'
761      if (!LHS.isInvalid()) {
762        LHS = Actions.ActOnPostfixUnaryOp(CurScope, Tok.getLocation(),
763                                          Tok.getKind(), LHS.release());
764      }
765      ConsumeToken();
766      break;
767    }
768  }
769}
770
771
772/// ParseSizeofAlignofExpression - Parse a sizeof or alignof expression.
773///       unary-expression:  [C99 6.5.3]
774///         'sizeof' unary-expression
775///         'sizeof' '(' type-name ')'
776/// [GNU]   '__alignof' unary-expression
777/// [GNU]   '__alignof' '(' type-name ')'
778/// [C++0x] 'alignof' '(' type-id ')'
779Parser::OwningExprResult Parser::ParseSizeofAlignofExpression() {
780  assert((Tok.is(tok::kw_sizeof) || Tok.is(tok::kw___alignof)
781          || Tok.is(tok::kw_alignof)) &&
782         "Not a sizeof/alignof expression!");
783  Token OpTok = Tok;
784  ConsumeToken();
785
786  // If the operand doesn't start with an '(', it must be an expression.
787  OwningExprResult Operand(Actions);
788  if (Tok.isNot(tok::l_paren)) {
789    Operand = ParseCastExpression(true);
790  } else {
791    // If it starts with a '(', we know that it is either a parenthesized
792    // type-name, or it is a unary-expression that starts with a compound
793    // literal, or starts with a primary-expression that is a parenthesized
794    // expression.
795    ParenParseOption ExprType = CastExpr;
796    TypeTy *CastTy;
797    SourceLocation LParenLoc = Tok.getLocation(), RParenLoc;
798    Operand = ParseParenExpression(ExprType, CastTy, RParenLoc);
799
800    // If ParseParenExpression parsed a '(typename)' sequence only, the this is
801    // sizeof/alignof a type.  Otherwise, it is sizeof/alignof an expression.
802    if (ExprType == CastExpr)
803      return Owned(Actions.ActOnSizeOfAlignOfExpr(OpTok.getLocation(),
804                                            OpTok.is(tok::kw_sizeof),
805                                            /*isType=*/true, CastTy,
806                                            SourceRange(LParenLoc, RParenLoc)));
807
808    // If this is a parenthesized expression, it is the start of a
809    // unary-expression, but doesn't include any postfix pieces.  Parse these
810    // now if present.
811    Operand = ParsePostfixExpressionSuffix(move(Operand));
812  }
813
814  // If we get here, the operand to the sizeof/alignof was an expresion.
815  if (!Operand.isInvalid())
816    Operand = Actions.ActOnSizeOfAlignOfExpr(OpTok.getLocation(),
817                                             OpTok.is(tok::kw_sizeof),
818                                             /*isType=*/false,
819                                             Operand.release(), SourceRange());
820  return move(Operand);
821}
822
823/// ParseBuiltinPrimaryExpression
824///
825///       primary-expression: [C99 6.5.1]
826/// [GNU]   '__builtin_va_arg' '(' assignment-expression ',' type-name ')'
827/// [GNU]   '__builtin_offsetof' '(' type-name ',' offsetof-member-designator')'
828/// [GNU]   '__builtin_choose_expr' '(' assign-expr ',' assign-expr ','
829///                                     assign-expr ')'
830/// [GNU]   '__builtin_types_compatible_p' '(' type-name ',' type-name ')'
831/// [CLANG] '__builtin_overload' '(' expr (',' expr)* ')'
832///
833/// [GNU] offsetof-member-designator:
834/// [GNU]   identifier
835/// [GNU]   offsetof-member-designator '.' identifier
836/// [GNU]   offsetof-member-designator '[' expression ']'
837///
838Parser::OwningExprResult Parser::ParseBuiltinPrimaryExpression() {
839  OwningExprResult Res(Actions);
840  const IdentifierInfo *BuiltinII = Tok.getIdentifierInfo();
841
842  tok::TokenKind T = Tok.getKind();
843  SourceLocation StartLoc = ConsumeToken();   // Eat the builtin identifier.
844
845  // All of these start with an open paren.
846  if (Tok.isNot(tok::l_paren))
847    return ExprError(Diag(Tok, diag::err_expected_lparen_after_id)
848                       << BuiltinII);
849
850  SourceLocation LParenLoc = ConsumeParen();
851  // TODO: Build AST.
852
853  switch (T) {
854  default: assert(0 && "Not a builtin primary expression!");
855  case tok::kw___builtin_va_arg: {
856    OwningExprResult Expr(ParseAssignmentExpression());
857    if (Expr.isInvalid()) {
858      SkipUntil(tok::r_paren);
859      return ExprError();
860    }
861
862    if (ExpectAndConsume(tok::comma, diag::err_expected_comma, "",tok::r_paren))
863      return ExprError();
864
865    TypeTy *Ty = ParseTypeName();
866
867    if (Tok.isNot(tok::r_paren)) {
868      Diag(Tok, diag::err_expected_rparen);
869      return ExprError();
870    }
871    Res = Actions.ActOnVAArg(StartLoc, Expr.release(), Ty, ConsumeParen());
872    break;
873  }
874  case tok::kw___builtin_offsetof: {
875    SourceLocation TypeLoc = Tok.getLocation();
876    TypeTy *Ty = ParseTypeName();
877
878    if (ExpectAndConsume(tok::comma, diag::err_expected_comma, "",tok::r_paren))
879      return ExprError();
880
881    // We must have at least one identifier here.
882    if (Tok.isNot(tok::identifier)) {
883      Diag(Tok, diag::err_expected_ident);
884      SkipUntil(tok::r_paren);
885      return ExprError();
886    }
887
888    // Keep track of the various subcomponents we see.
889    llvm::SmallVector<Action::OffsetOfComponent, 4> Comps;
890
891    Comps.push_back(Action::OffsetOfComponent());
892    Comps.back().isBrackets = false;
893    Comps.back().U.IdentInfo = Tok.getIdentifierInfo();
894    Comps.back().LocStart = Comps.back().LocEnd = ConsumeToken();
895
896    // FIXME: This loop leaks the index expressions on error.
897    while (1) {
898      if (Tok.is(tok::period)) {
899        // offsetof-member-designator: offsetof-member-designator '.' identifier
900        Comps.push_back(Action::OffsetOfComponent());
901        Comps.back().isBrackets = false;
902        Comps.back().LocStart = ConsumeToken();
903
904        if (Tok.isNot(tok::identifier)) {
905          Diag(Tok, diag::err_expected_ident);
906          SkipUntil(tok::r_paren);
907          return ExprError();
908        }
909        Comps.back().U.IdentInfo = Tok.getIdentifierInfo();
910        Comps.back().LocEnd = ConsumeToken();
911
912      } else if (Tok.is(tok::l_square)) {
913        // offsetof-member-designator: offsetof-member-design '[' expression ']'
914        Comps.push_back(Action::OffsetOfComponent());
915        Comps.back().isBrackets = true;
916        Comps.back().LocStart = ConsumeBracket();
917        Res = ParseExpression();
918        if (Res.isInvalid()) {
919          SkipUntil(tok::r_paren);
920          return move(Res);
921        }
922        Comps.back().U.E = Res.release();
923
924        Comps.back().LocEnd =
925          MatchRHSPunctuation(tok::r_square, Comps.back().LocStart);
926      } else if (Tok.is(tok::r_paren)) {
927        Res = Actions.ActOnBuiltinOffsetOf(CurScope, StartLoc, TypeLoc, Ty,
928                                           &Comps[0], Comps.size(),
929                                           ConsumeParen());
930        break;
931      } else {
932        // Error occurred.
933        return ExprError();
934      }
935    }
936    break;
937  }
938  case tok::kw___builtin_choose_expr: {
939    OwningExprResult Cond(ParseAssignmentExpression());
940    if (Cond.isInvalid()) {
941      SkipUntil(tok::r_paren);
942      return move(Cond);
943    }
944    if (ExpectAndConsume(tok::comma, diag::err_expected_comma, "",tok::r_paren))
945      return ExprError();
946
947    OwningExprResult Expr1(ParseAssignmentExpression());
948    if (Expr1.isInvalid()) {
949      SkipUntil(tok::r_paren);
950      return move(Expr1);
951    }
952    if (ExpectAndConsume(tok::comma, diag::err_expected_comma, "",tok::r_paren))
953      return ExprError();
954
955    OwningExprResult Expr2(ParseAssignmentExpression());
956    if (Expr2.isInvalid()) {
957      SkipUntil(tok::r_paren);
958      return move(Expr2);
959    }
960    if (Tok.isNot(tok::r_paren)) {
961      Diag(Tok, diag::err_expected_rparen);
962      return ExprError();
963    }
964    Res = Actions.ActOnChooseExpr(StartLoc, Cond.release(), Expr1.release(),
965                                  Expr2.release(), ConsumeParen());
966    break;
967  }
968  case tok::kw___builtin_overload: {
969    ExprVector ArgExprs(Actions);
970    llvm::SmallVector<SourceLocation, 8> CommaLocs;
971
972    // For each iteration through the loop look for assign-expr followed by a
973    // comma.  If there is no comma, break and attempt to match r-paren.
974    if (Tok.isNot(tok::r_paren)) {
975      while (1) {
976        OwningExprResult ArgExpr(ParseAssignmentExpression());
977        if (ArgExpr.isInvalid()) {
978          SkipUntil(tok::r_paren);
979          return ExprError();
980        } else
981          ArgExprs.push_back(ArgExpr.release());
982
983        if (Tok.isNot(tok::comma))
984          break;
985        // Move to the next argument, remember where the comma was.
986        CommaLocs.push_back(ConsumeToken());
987      }
988    }
989
990    // Attempt to consume the r-paren
991    if (Tok.isNot(tok::r_paren)) {
992      Diag(Tok, diag::err_expected_rparen);
993      SkipUntil(tok::r_paren);
994      return ExprError();
995    }
996    Res = Actions.ActOnOverloadExpr(ArgExprs.take(), ArgExprs.size(),
997                                    &CommaLocs[0], StartLoc, ConsumeParen());
998    break;
999  }
1000  case tok::kw___builtin_types_compatible_p:
1001    TypeTy *Ty1 = ParseTypeName();
1002
1003    if (ExpectAndConsume(tok::comma, diag::err_expected_comma, "",tok::r_paren))
1004      return ExprError();
1005
1006    TypeTy *Ty2 = ParseTypeName();
1007
1008    if (Tok.isNot(tok::r_paren)) {
1009      Diag(Tok, diag::err_expected_rparen);
1010      return ExprError();
1011    }
1012    Res = Actions.ActOnTypesCompatibleExpr(StartLoc, Ty1, Ty2, ConsumeParen());
1013    break;
1014  }
1015
1016  // These can be followed by postfix-expr pieces because they are
1017  // primary-expressions.
1018  return ParsePostfixExpressionSuffix(move(Res));
1019}
1020
1021/// ParseParenExpression - This parses the unit that starts with a '(' token,
1022/// based on what is allowed by ExprType.  The actual thing parsed is returned
1023/// in ExprType.
1024///
1025///       primary-expression: [C99 6.5.1]
1026///         '(' expression ')'
1027/// [GNU]   '(' compound-statement ')'      (if !ParenExprOnly)
1028///       postfix-expression: [C99 6.5.2]
1029///         '(' type-name ')' '{' initializer-list '}'
1030///         '(' type-name ')' '{' initializer-list ',' '}'
1031///       cast-expression: [C99 6.5.4]
1032///         '(' type-name ')' cast-expression
1033///
1034Parser::OwningExprResult
1035Parser::ParseParenExpression(ParenParseOption &ExprType,
1036                             TypeTy *&CastTy, SourceLocation &RParenLoc) {
1037  assert(Tok.is(tok::l_paren) && "Not a paren expr!");
1038  SourceLocation OpenLoc = ConsumeParen();
1039  OwningExprResult Result(Actions, true);
1040  CastTy = 0;
1041
1042  if (ExprType >= CompoundStmt && Tok.is(tok::l_brace)) {
1043    Diag(Tok, diag::ext_gnu_statement_expr);
1044    OwningStmtResult Stmt(ParseCompoundStatement(true));
1045    ExprType = CompoundStmt;
1046
1047    // If the substmt parsed correctly, build the AST node.
1048    if (!Stmt.isInvalid() && Tok.is(tok::r_paren))
1049      Result = Actions.ActOnStmtExpr(
1050        OpenLoc, Stmt.release(), Tok.getLocation());
1051
1052  } else if (ExprType >= CompoundLiteral && isTypeIdInParens()) {
1053    // Otherwise, this is a compound literal expression or cast expression.
1054    TypeTy *Ty = ParseTypeName();
1055
1056    // Match the ')'.
1057    if (Tok.is(tok::r_paren))
1058      RParenLoc = ConsumeParen();
1059    else
1060      MatchRHSPunctuation(tok::r_paren, OpenLoc);
1061
1062    if (Tok.is(tok::l_brace)) {
1063      if (!getLang().C99)   // Compound literals don't exist in C90.
1064        Diag(OpenLoc, diag::ext_c99_compound_literal);
1065      Result = ParseInitializer();
1066      ExprType = CompoundLiteral;
1067      if (!Result.isInvalid())
1068        return Owned(Actions.ActOnCompoundLiteral(OpenLoc, Ty, RParenLoc,
1069                                                  Result.release()));
1070      return move(Result);
1071    }
1072
1073    if (ExprType == CastExpr) {
1074      // Note that this doesn't parse the subsequence cast-expression, it just
1075      // returns the parsed type to the callee.
1076      ExprType = CastExpr;
1077      CastTy = Ty;
1078      return OwningExprResult(Actions);
1079    }
1080
1081    Diag(Tok, diag::err_expected_lbrace_in_compound_literal);
1082    return ExprError();
1083  } else {
1084    Result = ParseExpression();
1085    ExprType = SimpleExpr;
1086    if (!Result.isInvalid() && Tok.is(tok::r_paren))
1087      Result = Actions.ActOnParenExpr(OpenLoc, Tok.getLocation(),
1088                                      Result.release());
1089  }
1090
1091  // Match the ')'.
1092  if (Result.isInvalid()) {
1093    SkipUntil(tok::r_paren);
1094    return ExprError();
1095  }
1096
1097  if (Tok.is(tok::r_paren))
1098    RParenLoc = ConsumeParen();
1099  else
1100    MatchRHSPunctuation(tok::r_paren, OpenLoc);
1101
1102  return move(Result);
1103}
1104
1105/// ParseStringLiteralExpression - This handles the various token types that
1106/// form string literals, and also handles string concatenation [C99 5.1.1.2,
1107/// translation phase #6].
1108///
1109///       primary-expression: [C99 6.5.1]
1110///         string-literal
1111Parser::OwningExprResult Parser::ParseStringLiteralExpression() {
1112  assert(isTokenStringLiteral() && "Not a string literal!");
1113
1114  // String concat.  Note that keywords like __func__ and __FUNCTION__ are not
1115  // considered to be strings for concatenation purposes.
1116  llvm::SmallVector<Token, 4> StringToks;
1117
1118  do {
1119    StringToks.push_back(Tok);
1120    ConsumeStringToken();
1121  } while (isTokenStringLiteral());
1122
1123  // Pass the set of string tokens, ready for concatenation, to the actions.
1124  return Owned(Actions.ActOnStringLiteral(&StringToks[0], StringToks.size()));
1125}
1126
1127/// ParseExpressionList - Used for C/C++ (argument-)expression-list.
1128///
1129///       argument-expression-list:
1130///         assignment-expression
1131///         argument-expression-list , assignment-expression
1132///
1133/// [C++] expression-list:
1134/// [C++]   assignment-expression
1135/// [C++]   expression-list , assignment-expression
1136///
1137bool Parser::ParseExpressionList(ExprListTy &Exprs, CommaLocsTy &CommaLocs) {
1138  while (1) {
1139    OwningExprResult Expr(ParseAssignmentExpression());
1140    if (Expr.isInvalid())
1141      return true;
1142
1143    Exprs.push_back(Expr.release());
1144
1145    if (Tok.isNot(tok::comma))
1146      return false;
1147    // Move to the next argument, remember where the comma was.
1148    CommaLocs.push_back(ConsumeToken());
1149  }
1150}
1151
1152/// ParseBlockLiteralExpression - Parse a block literal, which roughly looks
1153/// like ^(int x){ return x+1; }
1154///
1155///         block-literal:
1156/// [clang]   '^' block-args[opt] compound-statement
1157/// [clang] block-args:
1158/// [clang]   '(' parameter-list ')'
1159///
1160Parser::OwningExprResult Parser::ParseBlockLiteralExpression() {
1161  assert(Tok.is(tok::caret) && "block literal starts with ^");
1162  SourceLocation CaretLoc = ConsumeToken();
1163
1164  // Enter a scope to hold everything within the block.  This includes the
1165  // argument decls, decls within the compound expression, etc.  This also
1166  // allows determining whether a variable reference inside the block is
1167  // within or outside of the block.
1168  ParseScope BlockScope(this, Scope::BlockScope|Scope::FnScope|Scope::BreakScope|
1169                              Scope::ContinueScope|Scope::DeclScope);
1170
1171  // Inform sema that we are starting a block.
1172  Actions.ActOnBlockStart(CaretLoc, CurScope);
1173
1174  // Parse the return type if present.
1175  DeclSpec DS;
1176  Declarator ParamInfo(DS, Declarator::PrototypeContext);
1177
1178  // If this block has arguments, parse them.  There is no ambiguity here with
1179  // the expression case, because the expression case requires a parameter list.
1180  if (Tok.is(tok::l_paren)) {
1181    ParseParenDeclarator(ParamInfo);
1182    // Parse the pieces after the identifier as if we had "int(...)".
1183    ParamInfo.SetIdentifier(0, CaretLoc);
1184    if (ParamInfo.getInvalidType()) {
1185      // If there was an error parsing the arguments, they may have tried to use
1186      // ^(x+y) which requires an argument list.  Just skip the whole block
1187      // literal.
1188      return ExprError();
1189    }
1190  } else {
1191    // Otherwise, pretend we saw (void).
1192    ParamInfo.AddTypeInfo(DeclaratorChunk::getFunction(true, false,
1193                                                       0, 0, 0, CaretLoc));
1194  }
1195
1196  // Inform sema that we are starting a block.
1197  Actions.ActOnBlockArguments(ParamInfo);
1198
1199  OwningExprResult Result(Actions, true);
1200  if (Tok.is(tok::l_brace)) {
1201    OwningStmtResult Stmt(ParseCompoundStatementBody());
1202    if (!Stmt.isInvalid()) {
1203      Result = Actions.ActOnBlockStmtExpr(CaretLoc, Stmt.release(), CurScope);
1204    } else {
1205      Actions.ActOnBlockError(CaretLoc, CurScope);
1206    }
1207  }
1208  return move(Result);
1209}
1210
1211