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//===--- 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 "clang/Parse/Parser.h"
#include "RAIIObjectsForParser.h"
#include "clang/Parse/ParseDiagnostic.h"
#include "clang/Sema/Designator.h"
#include "clang/Sema/Scope.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/raw_ostream.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.str());
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(),
ParsedType(),
0);
}
// 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),
0);
}
// 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 (Sema::ObjCMessageKind Kind
= Actions.getObjCMessageKind(getCurScope(), II, IILoc,
II == Ident_super,
NextToken().is(tok::period),
ReceiverType)) {
case Sema::ObjCSuperMessage:
case Sema::ObjCClassMessage:
CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
if (Kind == Sema::ObjCSuperMessage)
return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
ConsumeToken(),
ParsedType(),
0);
ConsumeToken(); // the identifier
if (!ReceiverType) {
SkipUntil(tok::r_square, StopAtSemi);
return ExprError();
}
return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
SourceLocation(),
ReceiverType,
0);
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(),
ParsedType(),
Idx.take());
}
// If this is a normal array designator, remember it.
if (Tok.isNot(tok::ellipsis)) {
Desig.AddDesignator(Designator::getArray(Idx.release(), 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.release(),
RHS.release(),
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());
}
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());
// If we couldn't parse the subelement, bail out.
if (!SubElt.isInvalid()) {
InitExprs.push_back(SubElt.release());
} 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.release());
else
InitExprsOk = false;
if (Tok.is(tok::comma)) {
ConsumeToken();
trailingComma = true;
}
if (Tok.is(tok::r_brace))
break;
}
Braces.consumeClose();
return !trailingComma;
}