lib/Parse/ParseInit.cpp - third_party/swift-clang - Git at Google

 //===--- ParseInit.cpp - Initializer Parsing ------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements initializer parsing as specified by C99 6.7.8.
 //
 //===----------------------------------------------------------------------===//

 #include "RAIIObjectsForParser.h"
 #include "clang/Parse/ParseDiagnostic.h"
 #include "clang/Parse/Parser.h"
 #include "clang/Sema/Designator.h"
 #include "clang/Sema/Scope.h"
 #include "llvm/ADT/SmallString.h"
 using namespace clang;


 /// MayBeDesignationStart - Return true if the current token might be the start
 /// of a designator.  If we can tell it is impossible that it is a designator,
 /// return false.
 bool Parser::MayBeDesignationStart() {
   switch (Tok.getKind()) {
   default:
     return false;

   case tok::period:      // designator: '.' identifier
     return true;

   case tok::l_square: {  // designator: array-designator
     if (!PP.getLangOpts().CPlusPlus11)
       return true;

     // C++11 lambda expressions and C99 designators can be ambiguous all the
     // way through the closing ']' and to the next character. Handle the easy
     // cases here, and fall back to tentative parsing if those fail.
     switch (PP.LookAhead(0).getKind()) {
     case tok::equal:
     case tok::r_square:
       // Definitely starts a lambda expression.
       return false;

     case tok::amp:
     case tok::kw_this:
     case tok::identifier:
       // We have to do additional analysis, because these could be the
       // start of a constant expression or a lambda capture list.
       break;

     default:
       // Anything not mentioned above cannot occur following a '[' in a
       // lambda expression.
       return true;
     }

     // Handle the complicated case below.
     break;
   }
   case tok::identifier:  // designation: identifier ':'
     return PP.LookAhead(0).is(tok::colon);
   }

   // Parse up to (at most) the token after the closing ']' to determine
   // whether this is a C99 designator or a lambda.
   TentativeParsingAction Tentative(*this);

   LambdaIntroducer Intro;
   bool SkippedInits = false;
   Optional<unsigned> DiagID(ParseLambdaIntroducer(Intro, &SkippedInits));

   if (DiagID) {
     // If this can't be a lambda capture list, it's a designator.
     Tentative.Revert();
     return true;
   }

   // Once we hit the closing square bracket, we look at the next
   // token. If it's an '=', this is a designator. Otherwise, it's a
   // lambda expression. This decision favors lambdas over the older
   // GNU designator syntax, which allows one to omit the '=', but is
   // consistent with GCC.
   tok::TokenKind Kind = Tok.getKind();
   // FIXME: If we didn't skip any inits, parse the lambda from here
   // rather than throwing away then reparsing the LambdaIntroducer.
   Tentative.Revert();
   return Kind == tok::equal;
 }

 static void CheckArrayDesignatorSyntax(Parser &P, SourceLocation Loc,
                                        Designation &Desig) {
   // If we have exactly one array designator, this used the GNU
   // 'designation: array-designator' extension, otherwise there should be no
   // designators at all!
   if (Desig.getNumDesignators() == 1 &&
       (Desig.getDesignator(0).isArrayDesignator() ||
        Desig.getDesignator(0).isArrayRangeDesignator()))
     P.Diag(Loc, diag::ext_gnu_missing_equal_designator);
   else if (Desig.getNumDesignators() > 0)
     P.Diag(Loc, diag::err_expected_equal_designator);
 }

 /// ParseInitializerWithPotentialDesignator - Parse the 'initializer' production
 /// checking to see if the token stream starts with a designator.
 ///
 ///       designation:
 ///         designator-list '='
 /// [GNU]   array-designator
 /// [GNU]   identifier ':'
 ///
 ///       designator-list:
 ///         designator
 ///         designator-list designator
 ///
 ///       designator:
 ///         array-designator
 ///         '.' identifier
 ///
 ///       array-designator:
 ///         '[' constant-expression ']'
 /// [GNU]   '[' constant-expression '...' constant-expression ']'
 ///
 /// NOTE: [OBC] allows '[ objc-receiver objc-message-args ]' as an
 /// initializer (because it is an expression).  We need to consider this case
 /// when parsing array designators.
 ///
 ExprResult Parser::ParseInitializerWithPotentialDesignator() {

   // If this is the old-style GNU extension:
   //   designation ::= identifier ':'
   // Handle it as a field designator.  Otherwise, this must be the start of a
   // normal expression.
   if (Tok.is(tok::identifier)) {
     const IdentifierInfo *FieldName = Tok.getIdentifierInfo();

     SmallString<256> NewSyntax;
     llvm::raw_svector_ostream(NewSyntax) << '.' << FieldName->getName()
                                          << " = ";

     SourceLocation NameLoc = ConsumeToken(); // Eat the identifier.

     assert(Tok.is(tok::colon) && "MayBeDesignationStart not working properly!");
     SourceLocation ColonLoc = ConsumeToken();

     Diag(NameLoc, diag::ext_gnu_old_style_field_designator)
       << FixItHint::CreateReplacement(SourceRange(NameLoc, ColonLoc),
                                       NewSyntax);

     Designation D;
     D.AddDesignator(Designator::getField(FieldName, SourceLocation(), NameLoc));
     return Actions.ActOnDesignatedInitializer(D, ColonLoc, true,
                                               ParseInitializer());
   }

   // Desig - This is initialized when we see our first designator.  We may have
   // an objc message send with no designator, so we don't want to create this
   // eagerly.
   Designation Desig;

   // Parse each designator in the designator list until we find an initializer.
   while (Tok.is(tok::period) || Tok.is(tok::l_square)) {
     if (Tok.is(tok::period)) {
       // designator: '.' identifier
       SourceLocation DotLoc = ConsumeToken();

       if (Tok.isNot(tok::identifier)) {
         Diag(Tok.getLocation(), diag::err_expected_field_designator);
         return ExprError();
       }

       Desig.AddDesignator(Designator::getField(Tok.getIdentifierInfo(), DotLoc,
                                                Tok.getLocation()));
       ConsumeToken(); // Eat the identifier.
       continue;
     }

     // We must have either an array designator now or an objc message send.
     assert(Tok.is(tok::l_square) && "Unexpected token!");

     // Handle the two forms of array designator:
     //   array-designator: '[' constant-expression ']'
     //   array-designator: '[' constant-expression '...' constant-expression ']'
     //
     // Also, we have to handle the case where the expression after the
     // designator an an objc message send: '[' objc-message-expr ']'.
     // Interesting cases are:
     //   [foo bar]         -> objc message send
     //   [foo]             -> array designator
     //   [foo ... bar]     -> array designator
     //   [4][foo bar]      -> obsolete GNU designation with objc message send.
     //
     // We do not need to check for an expression starting with [[ here. If it
     // contains an Objective-C message send, then it is not an ill-formed
     // attribute. If it is a lambda-expression within an array-designator, then
     // it will be rejected because a constant-expression cannot begin with a
     // lambda-expression.
     InMessageExpressionRAIIObject InMessage(*this, true);

     BalancedDelimiterTracker T(*this, tok::l_square);
     T.consumeOpen();
     SourceLocation StartLoc = T.getOpenLocation();

     ExprResult Idx;

     // If Objective-C is enabled and this is a typename (class message
     // send) or send to 'super', parse this as a message send
     // expression.  We handle C++ and C separately, since C++ requires
     // much more complicated parsing.
     if  (getLangOpts().ObjC1 && getLangOpts().CPlusPlus) {
       // Send to 'super'.
       if (Tok.is(tok::identifier) && Tok.getIdentifierInfo() == Ident_super &&
           NextToken().isNot(tok::period) &&
           getCurScope()->isInObjcMethodScope()) {
         CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
         return ParseAssignmentExprWithObjCMessageExprStart(
             StartLoc, ConsumeToken(), nullptr, nullptr);
       }

       // Parse the receiver, which is either a type or an expression.
       bool IsExpr;
       void *TypeOrExpr;
       if (ParseObjCXXMessageReceiver(IsExpr, TypeOrExpr)) {
         SkipUntil(tok::r_square, StopAtSemi);
         return ExprError();
       }

       // If the receiver was a type, we have a class message; parse
       // the rest of it.
       if (!IsExpr) {
         CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
         return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
                                                            SourceLocation(),
                                    ParsedType::getFromOpaquePtr(TypeOrExpr),
                                                            nullptr);
       }

       // If the receiver was an expression, we still don't know
       // whether we have a message send or an array designator; just
       // adopt the expression for further analysis below.
       // FIXME: potentially-potentially evaluated expression above?
       Idx = ExprResult(static_cast<Expr*>(TypeOrExpr));
     } else if (getLangOpts().ObjC1 && Tok.is(tok::identifier)) {
       IdentifierInfo *II = Tok.getIdentifierInfo();
       SourceLocation IILoc = Tok.getLocation();
       ParsedType ReceiverType;
       // Three cases. This is a message send to a type: [type foo]
       // This is a message send to super:  [super foo]
       // This is a message sent to an expr:  [super.bar foo]
       switch (Actions.getObjCMessageKind(
           getCurScope(), II, IILoc, II == Ident_super,
           NextToken().is(tok::period), ReceiverType)) {
       case Sema::ObjCSuperMessage:
         CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
         return ParseAssignmentExprWithObjCMessageExprStart(
             StartLoc, ConsumeToken(), nullptr, nullptr);

       case Sema::ObjCClassMessage:
         CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
         ConsumeToken(); // the identifier
         if (!ReceiverType) {
           SkipUntil(tok::r_square, StopAtSemi);
           return ExprError();
         }

         // Parse type arguments and protocol qualifiers.
         if (Tok.is(tok::less)) {
           SourceLocation NewEndLoc;
           TypeResult NewReceiverType
             = parseObjCTypeArgsAndProtocolQualifiers(IILoc, ReceiverType,
                                                      /*consumeLastToken=*/true,
                                                      NewEndLoc);
           if (!NewReceiverType.isUsable()) {
             SkipUntil(tok::r_square, StopAtSemi);
             return ExprError();
           }

           ReceiverType = NewReceiverType.get();
         }

         return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
                                                            SourceLocation(),
                                                            ReceiverType,
                                                            nullptr);

       case Sema::ObjCInstanceMessage:
         // Fall through; we'll just parse the expression and
         // (possibly) treat this like an Objective-C message send
         // later.
         break;
       }
     }

     // Parse the index expression, if we haven't already gotten one
     // above (which can only happen in Objective-C++).
     // Note that we parse this as an assignment expression, not a constant
     // expression (allowing *=, =, etc) to handle the objc case.  Sema needs
     // to validate that the expression is a constant.
     // FIXME: We also need to tell Sema that we're in a
     // potentially-potentially evaluated context.
     if (!Idx.get()) {
       Idx = ParseAssignmentExpression();
       if (Idx.isInvalid()) {
         SkipUntil(tok::r_square, StopAtSemi);
         return Idx;
       }
     }

     // Given an expression, we could either have a designator (if the next
     // tokens are '...' or ']' or an objc message send.  If this is an objc
     // message send, handle it now.  An objc-message send is the start of
     // an assignment-expression production.
     if (getLangOpts().ObjC1 && Tok.isNot(tok::ellipsis) &&
         Tok.isNot(tok::r_square)) {
       CheckArrayDesignatorSyntax(*this, Tok.getLocation(), Desig);
       return ParseAssignmentExprWithObjCMessageExprStart(
           StartLoc, SourceLocation(), nullptr, Idx.get());
     }

     // If this is a normal array designator, remember it.
     if (Tok.isNot(tok::ellipsis)) {
       Desig.AddDesignator(Designator::getArray(Idx.get(), StartLoc));
     } else {
       // Handle the gnu array range extension.
       Diag(Tok, diag::ext_gnu_array_range);
       SourceLocation EllipsisLoc = ConsumeToken();

       ExprResult RHS(ParseConstantExpression());
       if (RHS.isInvalid()) {
         SkipUntil(tok::r_square, StopAtSemi);
         return RHS;
       }
       Desig.AddDesignator(Designator::getArrayRange(Idx.get(),
                                                     RHS.get(),
                                                     StartLoc, EllipsisLoc));
     }

     T.consumeClose();
     Desig.getDesignator(Desig.getNumDesignators() - 1).setRBracketLoc(
                                                         T.getCloseLocation());
   }

   // Okay, we're done with the designator sequence.  We know that there must be
   // at least one designator, because the only case we can get into this method
   // without a designator is when we have an objc message send.  That case is
   // handled and returned from above.
   assert(!Desig.empty() && "Designator is empty?");

   // Handle a normal designator sequence end, which is an equal.
   if (Tok.is(tok::equal)) {
     SourceLocation EqualLoc = ConsumeToken();
     return Actions.ActOnDesignatedInitializer(Desig, EqualLoc, false,
                                               ParseInitializer());
   }

   // We read some number of designators and found something that isn't an = or
   // an initializer.  If we have exactly one array designator, this
   // is the GNU 'designation: array-designator' extension.  Otherwise, it is a
   // parse error.
   if (Desig.getNumDesignators() == 1 &&
       (Desig.getDesignator(0).isArrayDesignator() ||
        Desig.getDesignator(0).isArrayRangeDesignator())) {
     Diag(Tok, diag::ext_gnu_missing_equal_designator)
       << FixItHint::CreateInsertion(Tok.getLocation(), "= ");
     return Actions.ActOnDesignatedInitializer(Desig, Tok.getLocation(),
                                               true, ParseInitializer());
   }

   Diag(Tok, diag::err_expected_equal_designator);
   return ExprError();
 }


 /// ParseBraceInitializer - Called when parsing an initializer that has a
 /// leading open brace.
 ///
 ///       initializer: [C99 6.7.8]
 ///         '{' initializer-list '}'
 ///         '{' initializer-list ',' '}'
 /// [GNU]   '{' '}'
 ///
 ///       initializer-list:
 ///         designation[opt] initializer ...[opt]
 ///         initializer-list ',' designation[opt] initializer ...[opt]
 ///
 ExprResult Parser::ParseBraceInitializer() {
   InMessageExpressionRAIIObject InMessage(*this, false);

   BalancedDelimiterTracker T(*this, tok::l_brace);
   T.consumeOpen();
   SourceLocation LBraceLoc = T.getOpenLocation();

   /// InitExprs - This is the actual list of expressions contained in the
   /// initializer.
   ExprVector InitExprs;

   if (Tok.is(tok::r_brace)) {
     // Empty initializers are a C++ feature and a GNU extension to C.
     if (!getLangOpts().CPlusPlus)
       Diag(LBraceLoc, diag::ext_gnu_empty_initializer);
     // Match the '}'.
     return Actions.ActOnInitList(LBraceLoc, None, ConsumeBrace());
   }

   // Enter an appropriate expression evaluation context for an initializer list.
   EnterExpressionEvaluationContext EnterContext(
       Actions, EnterExpressionEvaluationContext::InitList);

   bool InitExprsOk = true;

   while (1) {
     // Handle Microsoft __if_exists/if_not_exists if necessary.
     if (getLangOpts().MicrosoftExt && (Tok.is(tok::kw___if_exists) ||
         Tok.is(tok::kw___if_not_exists))) {
       if (ParseMicrosoftIfExistsBraceInitializer(InitExprs, InitExprsOk)) {
         if (Tok.isNot(tok::comma)) break;
         ConsumeToken();
       }
       if (Tok.is(tok::r_brace)) break;
       continue;
     }

     // Parse: designation[opt] initializer

     // If we know that this cannot be a designation, just parse the nested
     // initializer directly.
     ExprResult SubElt;
     if (MayBeDesignationStart())
       SubElt = ParseInitializerWithPotentialDesignator();
     else
       SubElt = ParseInitializer();

     if (Tok.is(tok::ellipsis))
       SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken());

     SubElt = Actions.CorrectDelayedTyposInExpr(SubElt.get());

     // If we couldn't parse the subelement, bail out.
     if (SubElt.isUsable()) {
       InitExprs.push_back(SubElt.get());
     } else {
       InitExprsOk = false;

       // We have two ways to try to recover from this error: if the code looks
       // grammatically ok (i.e. we have a comma coming up) try to continue
       // parsing the rest of the initializer.  This allows us to emit
       // diagnostics for later elements that we find.  If we don't see a comma,
       // assume there is a parse error, and just skip to recover.
       // FIXME: This comment doesn't sound right. If there is a r_brace
       // immediately, it can't be an error, since there is no other way of
       // leaving this loop except through this if.
       if (Tok.isNot(tok::comma)) {
         SkipUntil(tok::r_brace, StopBeforeMatch);
         break;
       }
     }

     // If we don't have a comma continued list, we're done.
     if (Tok.isNot(tok::comma)) break;

     // TODO: save comma locations if some client cares.
     ConsumeToken();

     // Handle trailing comma.
     if (Tok.is(tok::r_brace)) break;
   }

   bool closed = !T.consumeClose();

   if (InitExprsOk && closed)
     return Actions.ActOnInitList(LBraceLoc, InitExprs,
                                  T.getCloseLocation());

   return ExprError(); // an error occurred.
 }


 // Return true if a comma (or closing brace) is necessary after the
 // __if_exists/if_not_exists statement.
 bool Parser::ParseMicrosoftIfExistsBraceInitializer(ExprVector &InitExprs,
                                                     bool &InitExprsOk) {
   bool trailingComma = false;
   IfExistsCondition Result;
   if (ParseMicrosoftIfExistsCondition(Result))
     return false;

   BalancedDelimiterTracker Braces(*this, tok::l_brace);
   if (Braces.consumeOpen()) {
     Diag(Tok, diag::err_expected) << tok::l_brace;
     return false;
   }

   switch (Result.Behavior) {
   case IEB_Parse:
     // Parse the declarations below.
     break;

   case IEB_Dependent:
     Diag(Result.KeywordLoc, diag::warn_microsoft_dependent_exists)
       << Result.IsIfExists;
     // Fall through to skip.

   case IEB_Skip:
     Braces.skipToEnd();
     return false;
   }

   while (!isEofOrEom()) {
     trailingComma = false;
     // If we know that this cannot be a designation, just parse the nested
     // initializer directly.
     ExprResult SubElt;
     if (MayBeDesignationStart())
       SubElt = ParseInitializerWithPotentialDesignator();
     else
       SubElt = ParseInitializer();

     if (Tok.is(tok::ellipsis))
       SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken());

     // If we couldn't parse the subelement, bail out.
     if (!SubElt.isInvalid())
       InitExprs.push_back(SubElt.get());
     else
       InitExprsOk = false;

     if (Tok.is(tok::comma)) {
       ConsumeToken();
       trailingComma = true;
     }

     if (Tok.is(tok::r_brace))
       break;
   }

   Braces.consumeClose();

   return !trailingComma;
 }
	//===--- ParseInit.cpp - Initializer Parsing ------------------------------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file implements initializer parsing as specified by C99 6.7.8.
	//
	//===----------------------------------------------------------------------===//

	#include "RAIIObjectsForParser.h"
	#include "clang/Parse/ParseDiagnostic.h"
	#include "clang/Parse/Parser.h"
	#include "clang/Sema/Designator.h"
	#include "clang/Sema/Scope.h"
	#include "llvm/ADT/SmallString.h"
	using namespace clang;


	/// MayBeDesignationStart - Return true if the current token might be the start
	/// of a designator. If we can tell it is impossible that it is a designator,
	/// return false.
	bool Parser::MayBeDesignationStart() {
	switch (Tok.getKind()) {
	default:
	return false;

	case tok::period: // designator: '.' identifier
	return true;

	case tok::l_square: { // designator: array-designator
	if (!PP.getLangOpts().CPlusPlus11)
	return true;

	// C++11 lambda expressions and C99 designators can be ambiguous all the
	// way through the closing ']' and to the next character. Handle the easy
	// cases here, and fall back to tentative parsing if those fail.
	switch (PP.LookAhead(0).getKind()) {
	case tok::equal:
	case tok::r_square:
	// Definitely starts a lambda expression.
	return false;

	case tok::amp:
	case tok::kw_this:
	case tok::identifier:
	// We have to do additional analysis, because these could be the
	// start of a constant expression or a lambda capture list.
	break;

	default:
	// Anything not mentioned above cannot occur following a '[' in a
	// lambda expression.
	return true;
	}

	// Handle the complicated case below.
	break;
	}
	case tok::identifier: // designation: identifier ':'
	return PP.LookAhead(0).is(tok::colon);
	}

	// Parse up to (at most) the token after the closing ']' to determine
	// whether this is a C99 designator or a lambda.
	TentativeParsingAction Tentative(*this);

	LambdaIntroducer Intro;
	bool SkippedInits = false;
	Optional<unsigned> DiagID(ParseLambdaIntroducer(Intro, &SkippedInits));

	if (DiagID) {
	// If this can't be a lambda capture list, it's a designator.
	Tentative.Revert();
	return true;
	}

	// Once we hit the closing square bracket, we look at the next
	// token. If it's an '=', this is a designator. Otherwise, it's a
	// lambda expression. This decision favors lambdas over the older
	// GNU designator syntax, which allows one to omit the '=', but is
	// consistent with GCC.
	tok::TokenKind Kind = Tok.getKind();
	// FIXME: If we didn't skip any inits, parse the lambda from here
	// rather than throwing away then reparsing the LambdaIntroducer.
	Tentative.Revert();
	return Kind == tok::equal;
	}

	static void CheckArrayDesignatorSyntax(Parser &P, SourceLocation Loc,
	Designation &Desig) {
	// If we have exactly one array designator, this used the GNU
	// 'designation: array-designator' extension, otherwise there should be no
	// designators at all!
	if (Desig.getNumDesignators() == 1 &&
	(Desig.getDesignator(0).isArrayDesignator() \|\|
	Desig.getDesignator(0).isArrayRangeDesignator()))
	P.Diag(Loc, diag::ext_gnu_missing_equal_designator);
	else if (Desig.getNumDesignators() > 0)
	P.Diag(Loc, diag::err_expected_equal_designator);
	}

	/// ParseInitializerWithPotentialDesignator - Parse the 'initializer' production
	/// checking to see if the token stream starts with a designator.
	///
	/// designation:
	/// designator-list '='
	/// [GNU] array-designator
	/// [GNU] identifier ':'
	///
	/// designator-list:
	/// designator
	/// designator-list designator
	///
	/// designator:
	/// array-designator
	/// '.' identifier
	///
	/// array-designator:
	/// '[' constant-expression ']'
	/// [GNU] '[' constant-expression '...' constant-expression ']'
	///
	/// NOTE: [OBC] allows '[ objc-receiver objc-message-args ]' as an
	/// initializer (because it is an expression). We need to consider this case
	/// when parsing array designators.
	///
	ExprResult Parser::ParseInitializerWithPotentialDesignator() {

	// If this is the old-style GNU extension:
	// designation ::= identifier ':'
	// Handle it as a field designator. Otherwise, this must be the start of a
	// normal expression.
	if (Tok.is(tok::identifier)) {
	const IdentifierInfo *FieldName = Tok.getIdentifierInfo();

	SmallString<256> NewSyntax;
	llvm::raw_svector_ostream(NewSyntax) << '.' << FieldName->getName()
	<< " = ";

	SourceLocation NameLoc = ConsumeToken(); // Eat the identifier.

	assert(Tok.is(tok::colon) && "MayBeDesignationStart not working properly!");
	SourceLocation ColonLoc = ConsumeToken();

	Diag(NameLoc, diag::ext_gnu_old_style_field_designator)
	<< FixItHint::CreateReplacement(SourceRange(NameLoc, ColonLoc),
	NewSyntax);

	Designation D;
	D.AddDesignator(Designator::getField(FieldName, SourceLocation(), NameLoc));
	return Actions.ActOnDesignatedInitializer(D, ColonLoc, true,
	ParseInitializer());
	}

	// Desig - This is initialized when we see our first designator. We may have
	// an objc message send with no designator, so we don't want to create this
	// eagerly.
	Designation Desig;

	// Parse each designator in the designator list until we find an initializer.
	while (Tok.is(tok::period) \|\| Tok.is(tok::l_square)) {
	if (Tok.is(tok::period)) {
	// designator: '.' identifier
	SourceLocation DotLoc = ConsumeToken();

	if (Tok.isNot(tok::identifier)) {
	Diag(Tok.getLocation(), diag::err_expected_field_designator);
	return ExprError();
	}

	Desig.AddDesignator(Designator::getField(Tok.getIdentifierInfo(), DotLoc,
	Tok.getLocation()));
	ConsumeToken(); // Eat the identifier.
	continue;
	}

	// We must have either an array designator now or an objc message send.
	assert(Tok.is(tok::l_square) && "Unexpected token!");

	// Handle the two forms of array designator:
	// array-designator: '[' constant-expression ']'
	// array-designator: '[' constant-expression '...' constant-expression ']'
	//
	// Also, we have to handle the case where the expression after the
	// designator an an objc message send: '[' objc-message-expr ']'.
	// Interesting cases are:
	// [foo bar] -> objc message send
	// [foo] -> array designator
	// [foo ... bar] -> array designator
	// [4][foo bar] -> obsolete GNU designation with objc message send.
	//
	// We do not need to check for an expression starting with [[ here. If it
	// contains an Objective-C message send, then it is not an ill-formed
	// attribute. If it is a lambda-expression within an array-designator, then
	// it will be rejected because a constant-expression cannot begin with a
	// lambda-expression.
	InMessageExpressionRAIIObject InMessage(*this, true);

	BalancedDelimiterTracker T(*this, tok::l_square);
	T.consumeOpen();
	SourceLocation StartLoc = T.getOpenLocation();

	ExprResult Idx;

	// If Objective-C is enabled and this is a typename (class message
	// send) or send to 'super', parse this as a message send
	// expression. We handle C++ and C separately, since C++ requires
	// much more complicated parsing.
	if (getLangOpts().ObjC1 && getLangOpts().CPlusPlus) {
	// Send to 'super'.
	if (Tok.is(tok::identifier) && Tok.getIdentifierInfo() == Ident_super &&
	NextToken().isNot(tok::period) &&
	getCurScope()->isInObjcMethodScope()) {
	CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
	return ParseAssignmentExprWithObjCMessageExprStart(
	StartLoc, ConsumeToken(), nullptr, nullptr);
	}

	// Parse the receiver, which is either a type or an expression.
	bool IsExpr;
	void *TypeOrExpr;
	if (ParseObjCXXMessageReceiver(IsExpr, TypeOrExpr)) {
	SkipUntil(tok::r_square, StopAtSemi);
	return ExprError();
	}

	// If the receiver was a type, we have a class message; parse
	// the rest of it.
	if (!IsExpr) {
	CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
	return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
	SourceLocation(),
	ParsedType::getFromOpaquePtr(TypeOrExpr),
	nullptr);
	}

	// If the receiver was an expression, we still don't know
	// whether we have a message send or an array designator; just
	// adopt the expression for further analysis below.
	// FIXME: potentially-potentially evaluated expression above?
	Idx = ExprResult(static_cast<Expr*>(TypeOrExpr));
	} else if (getLangOpts().ObjC1 && Tok.is(tok::identifier)) {
	IdentifierInfo *II = Tok.getIdentifierInfo();
	SourceLocation IILoc = Tok.getLocation();
	ParsedType ReceiverType;
	// Three cases. This is a message send to a type: [type foo]
	// This is a message send to super: [super foo]
	// This is a message sent to an expr: [super.bar foo]
	switch (Actions.getObjCMessageKind(
	getCurScope(), II, IILoc, II == Ident_super,
	NextToken().is(tok::period), ReceiverType)) {
	case Sema::ObjCSuperMessage:
	CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
	return ParseAssignmentExprWithObjCMessageExprStart(
	StartLoc, ConsumeToken(), nullptr, nullptr);

	case Sema::ObjCClassMessage:
	CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
	ConsumeToken(); // the identifier
	if (!ReceiverType) {
	SkipUntil(tok::r_square, StopAtSemi);
	return ExprError();
	}

	// Parse type arguments and protocol qualifiers.
	if (Tok.is(tok::less)) {
	SourceLocation NewEndLoc;
	TypeResult NewReceiverType
	= parseObjCTypeArgsAndProtocolQualifiers(IILoc, ReceiverType,
	/consumeLastToken=/true,
	NewEndLoc);
	if (!NewReceiverType.isUsable()) {
	SkipUntil(tok::r_square, StopAtSemi);
	return ExprError();
	}

	ReceiverType = NewReceiverType.get();
	}

	return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
	SourceLocation(),
	ReceiverType,
	nullptr);

	case Sema::ObjCInstanceMessage:
	// Fall through; we'll just parse the expression and
	// (possibly) treat this like an Objective-C message send
	// later.
	break;
	}
	}

	// Parse the index expression, if we haven't already gotten one
	// above (which can only happen in Objective-C++).
	// Note that we parse this as an assignment expression, not a constant
	// expression (allowing *=, =, etc) to handle the objc case. Sema needs
	// to validate that the expression is a constant.
	// FIXME: We also need to tell Sema that we're in a
	// potentially-potentially evaluated context.
	if (!Idx.get()) {
	Idx = ParseAssignmentExpression();
	if (Idx.isInvalid()) {
	SkipUntil(tok::r_square, StopAtSemi);
	return Idx;
	}
	}

	// Given an expression, we could either have a designator (if the next
	// tokens are '...' or ']' or an objc message send. If this is an objc
	// message send, handle it now. An objc-message send is the start of
	// an assignment-expression production.
	if (getLangOpts().ObjC1 && Tok.isNot(tok::ellipsis) &&
	Tok.isNot(tok::r_square)) {
	CheckArrayDesignatorSyntax(*this, Tok.getLocation(), Desig);
	return ParseAssignmentExprWithObjCMessageExprStart(
	StartLoc, SourceLocation(), nullptr, Idx.get());
	}

	// If this is a normal array designator, remember it.
	if (Tok.isNot(tok::ellipsis)) {
	Desig.AddDesignator(Designator::getArray(Idx.get(), StartLoc));
	} else {
	// Handle the gnu array range extension.
	Diag(Tok, diag::ext_gnu_array_range);
	SourceLocation EllipsisLoc = ConsumeToken();

	ExprResult RHS(ParseConstantExpression());
	if (RHS.isInvalid()) {
	SkipUntil(tok::r_square, StopAtSemi);
	return RHS;
	}
	Desig.AddDesignator(Designator::getArrayRange(Idx.get(),
	RHS.get(),
	StartLoc, EllipsisLoc));
	}

	T.consumeClose();
	Desig.getDesignator(Desig.getNumDesignators() - 1).setRBracketLoc(
	T.getCloseLocation());
	}

	// Okay, we're done with the designator sequence. We know that there must be
	// at least one designator, because the only case we can get into this method
	// without a designator is when we have an objc message send. That case is
	// handled and returned from above.
	assert(!Desig.empty() && "Designator is empty?");

	// Handle a normal designator sequence end, which is an equal.
	if (Tok.is(tok::equal)) {
	SourceLocation EqualLoc = ConsumeToken();
	return Actions.ActOnDesignatedInitializer(Desig, EqualLoc, false,
	ParseInitializer());
	}

	// We read some number of designators and found something that isn't an = or
	// an initializer. If we have exactly one array designator, this
	// is the GNU 'designation: array-designator' extension. Otherwise, it is a
	// parse error.
	if (Desig.getNumDesignators() == 1 &&
	(Desig.getDesignator(0).isArrayDesignator() \|\|
	Desig.getDesignator(0).isArrayRangeDesignator())) {
	Diag(Tok, diag::ext_gnu_missing_equal_designator)
	<< FixItHint::CreateInsertion(Tok.getLocation(), "= ");
	return Actions.ActOnDesignatedInitializer(Desig, Tok.getLocation(),
	true, ParseInitializer());
	}

	Diag(Tok, diag::err_expected_equal_designator);
	return ExprError();
	}


	/// ParseBraceInitializer - Called when parsing an initializer that has a
	/// leading open brace.
	///
	/// initializer: [C99 6.7.8]
	/// '{' initializer-list '}'
	/// '{' initializer-list ',' '}'
	/// [GNU] '{' '}'
	///
	/// initializer-list:
	/// designation[opt] initializer ...[opt]
	/// initializer-list ',' designation[opt] initializer ...[opt]
	///
	ExprResult Parser::ParseBraceInitializer() {
	InMessageExpressionRAIIObject InMessage(*this, false);

	BalancedDelimiterTracker T(*this, tok::l_brace);
	T.consumeOpen();
	SourceLocation LBraceLoc = T.getOpenLocation();

	/// InitExprs - This is the actual list of expressions contained in the
	/// initializer.
	ExprVector InitExprs;

	if (Tok.is(tok::r_brace)) {
	// Empty initializers are a C++ feature and a GNU extension to C.
	if (!getLangOpts().CPlusPlus)
	Diag(LBraceLoc, diag::ext_gnu_empty_initializer);
	// Match the '}'.
	return Actions.ActOnInitList(LBraceLoc, None, ConsumeBrace());
	}

	// Enter an appropriate expression evaluation context for an initializer list.
	EnterExpressionEvaluationContext EnterContext(
	Actions, EnterExpressionEvaluationContext::InitList);

	bool InitExprsOk = true;

	while (1) {
	// Handle Microsoft __if_exists/if_not_exists if necessary.
	if (getLangOpts().MicrosoftExt && (Tok.is(tok::kw___if_exists) \|\|
	Tok.is(tok::kw___if_not_exists))) {
	if (ParseMicrosoftIfExistsBraceInitializer(InitExprs, InitExprsOk)) {
	if (Tok.isNot(tok::comma)) break;
	ConsumeToken();
	}
	if (Tok.is(tok::r_brace)) break;
	continue;
	}

	// Parse: designation[opt] initializer

	// If we know that this cannot be a designation, just parse the nested
	// initializer directly.
	ExprResult SubElt;
	if (MayBeDesignationStart())
	SubElt = ParseInitializerWithPotentialDesignator();
	else
	SubElt = ParseInitializer();

	if (Tok.is(tok::ellipsis))
	SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken());

	SubElt = Actions.CorrectDelayedTyposInExpr(SubElt.get());

	// If we couldn't parse the subelement, bail out.
	if (SubElt.isUsable()) {
	InitExprs.push_back(SubElt.get());
	} else {
	InitExprsOk = false;

	// We have two ways to try to recover from this error: if the code looks
	// grammatically ok (i.e. we have a comma coming up) try to continue
	// parsing the rest of the initializer. This allows us to emit
	// diagnostics for later elements that we find. If we don't see a comma,
	// assume there is a parse error, and just skip to recover.
	// FIXME: This comment doesn't sound right. If there is a r_brace
	// immediately, it can't be an error, since there is no other way of
	// leaving this loop except through this if.
	if (Tok.isNot(tok::comma)) {
	SkipUntil(tok::r_brace, StopBeforeMatch);
	break;
	}
	}

	// If we don't have a comma continued list, we're done.
	if (Tok.isNot(tok::comma)) break;

	// TODO: save comma locations if some client cares.
	ConsumeToken();

	// Handle trailing comma.
	if (Tok.is(tok::r_brace)) break;
	}

	bool closed = !T.consumeClose();

	if (InitExprsOk && closed)
	return Actions.ActOnInitList(LBraceLoc, InitExprs,
	T.getCloseLocation());

	return ExprError(); // an error occurred.
	}


	// Return true if a comma (or closing brace) is necessary after the
	// __if_exists/if_not_exists statement.
	bool Parser::ParseMicrosoftIfExistsBraceInitializer(ExprVector &InitExprs,
	bool &InitExprsOk) {
	bool trailingComma = false;
	IfExistsCondition Result;
	if (ParseMicrosoftIfExistsCondition(Result))
	return false;

	BalancedDelimiterTracker Braces(*this, tok::l_brace);
	if (Braces.consumeOpen()) {
	Diag(Tok, diag::err_expected) << tok::l_brace;
	return false;
	}

	switch (Result.Behavior) {
	case IEB_Parse:
	// Parse the declarations below.
	break;

	case IEB_Dependent:
	Diag(Result.KeywordLoc, diag::warn_microsoft_dependent_exists)
	<< Result.IsIfExists;
	// Fall through to skip.

	case IEB_Skip:
	Braces.skipToEnd();
	return false;
	}

	while (!isEofOrEom()) {
	trailingComma = false;
	// If we know that this cannot be a designation, just parse the nested
	// initializer directly.
	ExprResult SubElt;
	if (MayBeDesignationStart())
	SubElt = ParseInitializerWithPotentialDesignator();
	else
	SubElt = ParseInitializer();

	if (Tok.is(tok::ellipsis))
	SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken());

	// If we couldn't parse the subelement, bail out.
	if (!SubElt.isInvalid())
	InitExprs.push_back(SubElt.get());
	else
	InitExprsOk = false;

	if (Tok.is(tok::comma)) {
	ConsumeToken();
	trailingComma = true;
	}

	if (Tok.is(tok::r_brace))
	break;
	}

	Braces.consumeClose();

	return !trailingComma;
	}