Disambiguation of '[[':
* In C++11, '[[' is ill-formed unless it starts an attribute-specifier. Reject
array sizes and array indexes which begin with a lambda-expression. Recover by
parsing the lambda as a lambda.
* In Objective-C++11, either '[' could be the start of a message-send.
Fully disambiguate this case: it turns out that the grammars of message-sends,
lambdas and attributes do not actually overlap. Accept any occurrence of '[['
where either '[' starts a message send, but reject a lambda in an array index
just like in C++11 mode.
Implement a couple of changes to the attribute wording which occurred after our
attributes implementation landed:
* In a function-declaration, the attributes go after the exception specification,
not after the right paren.
* A reference type can have attributes applied.
* An 'identifier' in an attribute can also be a keyword. Support for alternative
tokens (iso646 keywords) in attributes to follow.
And some bug fixes:
* Parse attributes after declarator-ids, even if they are not simple identifiers.
* Do not accept attributes after a parenthesized declarator.
* Accept attributes after an array size in a new-type-id.
* Partially disamiguate 'delete' followed by a lambda. More work is required
here for the case where the lambda-introducer is '[]'.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154369 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseTentative.cpp b/lib/Parse/ParseTentative.cpp
index b650169..18bc0dd 100644
--- a/lib/Parse/ParseTentative.cpp
+++ b/lib/Parse/ParseTentative.cpp
@@ -374,91 +374,167 @@
return TPR == TPResult::True();
}
-/// isCXX0XAttributeSpecifier - returns true if this is a C++0x
-/// attribute-specifier. By default, unless in Obj-C++, only a cursory check is
-/// performed that will simply return true if a [[ is seen. Currently C++ has no
-/// syntactical ambiguities from this check, but it may inhibit error recovery.
-/// If CheckClosing is true, a check is made for closing ]] brackets.
+/// \brief Returns true if this is a C++11 attribute-specifier. Per
+/// C++11 [dcl.attr.grammar]p6, two consecutive left square bracket tokens
+/// always introduce an attribute. In Objective-C++11, this rule does not
+/// apply if either '[' begins a message-send.
///
-/// If given, After is set to the token after the attribute-specifier so that
-/// appropriate parsing decisions can be made; it is left untouched if false is
-/// returned.
+/// If Disambiguate is true, we try harder to determine whether a '[[' starts
+/// an attribute-specifier, and return CAK_InvalidAttributeSpecifier if not.
///
-/// FIXME: If an error is in the closing ]] brackets, the program assumes
-/// the absence of an attribute-specifier, which can cause very yucky errors
-/// to occur.
+/// If OuterMightBeMessageSend is true, we assume the outer '[' is either an
+/// Obj-C message send or the start of an attribute. Otherwise, we assume it
+/// is not an Obj-C message send.
///
-/// [C++0x] attribute-specifier:
+/// C++11 [dcl.attr.grammar]:
+///
+/// attribute-specifier:
/// '[' '[' attribute-list ']' ']'
/// alignment-specifier
///
-/// [C++0x] attribute-list:
+/// attribute-list:
/// attribute[opt]
/// attribute-list ',' attribute[opt]
+/// attribute '...'
+/// attribute-list ',' attribute '...'
///
-/// [C++0x] attribute:
+/// attribute:
/// attribute-token attribute-argument-clause[opt]
///
-/// [C++0x] attribute-token:
+/// attribute-token:
/// identifier
-/// attribute-scoped-token
+/// identifier '::' identifier
///
-/// [C++0x] attribute-scoped-token:
-/// attribute-namespace '::' identifier
-///
-/// [C++0x] attribute-namespace:
-/// identifier
-///
-/// [C++0x] attribute-argument-clause:
+/// attribute-argument-clause:
/// '(' balanced-token-seq ')'
-///
-/// [C++0x] balanced-token-seq:
-/// balanced-token
-/// balanced-token-seq balanced-token
-///
-/// [C++0x] balanced-token:
-/// '(' balanced-token-seq ')'
-/// '[' balanced-token-seq ']'
-/// '{' balanced-token-seq '}'
-/// any token but '(', ')', '[', ']', '{', or '}'
-bool Parser::isCXX0XAttributeSpecifier (bool CheckClosing,
- tok::TokenKind *After) {
+Parser::CXX11AttributeKind
+Parser::isCXX11AttributeSpecifier(bool Disambiguate,
+ bool OuterMightBeMessageSend) {
if (Tok.is(tok::kw_alignas))
- return true;
+ return CAK_AttributeSpecifier;
if (Tok.isNot(tok::l_square) || NextToken().isNot(tok::l_square))
- return false;
-
- // No tentative parsing if we don't need to look for ]]
- if (!CheckClosing && !getLangOpts().ObjC1)
- return true;
-
- struct TentativeReverter {
- TentativeParsingAction PA;
+ return CAK_NotAttributeSpecifier;
- TentativeReverter (Parser& P)
- : PA(P)
- {}
- ~TentativeReverter () {
- PA.Revert();
- }
- } R(*this);
+ // No tentative parsing if we don't need to look for ']]' or a lambda.
+ if (!Disambiguate && !getLangOpts().ObjC1)
+ return CAK_AttributeSpecifier;
+
+ TentativeParsingAction PA(*this);
// Opening brackets were checked for above.
ConsumeBracket();
+
+ // Outside Obj-C++11, treat anything with a matching ']]' as an attribute.
+ if (!getLangOpts().ObjC1) {
+ ConsumeBracket();
+
+ bool IsAttribute = SkipUntil(tok::r_square, false);
+ IsAttribute &= Tok.is(tok::r_square);
+
+ PA.Revert();
+
+ return IsAttribute ? CAK_AttributeSpecifier : CAK_InvalidAttributeSpecifier;
+ }
+
+ // In Obj-C++11, we need to distinguish four situations:
+ // 1a) int x[[attr]]; C++11 attribute.
+ // 1b) [[attr]]; C++11 statement attribute.
+ // 2) int x[[obj](){ return 1; }()]; Lambda in array size/index.
+ // 3a) int x[[obj get]]; Message send in array size/index.
+ // 3b) [[Class alloc] init]; Message send in message send.
+ // 4) [[obj]{ return self; }() doStuff]; Lambda in message send.
+ // (1) is an attribute, (2) is ill-formed, and (3) and (4) are accepted.
+
+ // If we have a lambda-introducer, then this is definitely not a message send.
+ // FIXME: If this disambiguation is too slow, fold the tentative lambda parse
+ // into the tentative attribute parse below.
+ LambdaIntroducer Intro;
+ if (!TryParseLambdaIntroducer(Intro)) {
+ // A lambda cannot end with ']]', and an attribute must.
+ bool IsAttribute = Tok.is(tok::r_square);
+
+ PA.Revert();
+
+ if (IsAttribute)
+ // Case 1: C++11 attribute.
+ return CAK_AttributeSpecifier;
+
+ if (OuterMightBeMessageSend)
+ // Case 4: Lambda in message send.
+ return CAK_NotAttributeSpecifier;
+
+ // Case 2: Lambda in array size / index.
+ return CAK_InvalidAttributeSpecifier;
+ }
+
ConsumeBracket();
- // SkipUntil will handle balanced tokens, which are guaranteed in attributes.
- SkipUntil(tok::r_square, false);
+ // If we don't have a lambda-introducer, then we have an attribute or a
+ // message-send.
+ bool IsAttribute = true;
+ while (Tok.isNot(tok::r_square)) {
+ if (Tok.is(tok::comma)) {
+ // Case 1: Stray commas can only occur in attributes.
+ PA.Revert();
+ return CAK_AttributeSpecifier;
+ }
- if (Tok.isNot(tok::r_square))
- return false;
- ConsumeBracket();
+ // Parse the attribute-token, if present.
+ // C++11 [dcl.attr.grammar]:
+ // If a keyword or an alternative token that satisfies the syntactic
+ // requirements of an identifier is contained in an attribute-token,
+ // it is considered an identifier.
+ if (!Tok.getIdentifierInfo()) {
+ IsAttribute = false;
+ break;
+ }
+ ConsumeToken();
+ if (Tok.is(tok::coloncolon)) {
+ ConsumeToken();
+ if (!Tok.getIdentifierInfo()) {
+ IsAttribute = false;
+ break;
+ }
+ ConsumeToken();
+ }
- if (After)
- *After = Tok.getKind();
+ // Parse the attribute-argument-clause, if present.
+ if (Tok.is(tok::l_paren)) {
+ ConsumeParen();
+ if (!SkipUntil(tok::r_paren, false)) {
+ IsAttribute = false;
+ break;
+ }
+ }
- return true;
+ if (Tok.is(tok::ellipsis))
+ ConsumeToken();
+
+ if (Tok.isNot(tok::comma))
+ break;
+
+ ConsumeToken();
+ }
+
+ // An attribute must end ']]'.
+ if (IsAttribute) {
+ if (Tok.is(tok::r_square)) {
+ ConsumeBracket();
+ IsAttribute = Tok.is(tok::r_square);
+ } else {
+ IsAttribute = false;
+ }
+ }
+
+ PA.Revert();
+
+ if (IsAttribute)
+ // Case 1: C++11 statement attribute.
+ return CAK_AttributeSpecifier;
+
+ // Case 3: Message send.
+ return CAK_NotAttributeSpecifier;
}
/// declarator:
@@ -1217,11 +1293,13 @@
/// parameter-declaration-list ',' parameter-declaration
///
/// parameter-declaration:
-/// decl-specifier-seq declarator attributes[opt]
-/// decl-specifier-seq declarator attributes[opt] '=' assignment-expression
-/// decl-specifier-seq abstract-declarator[opt] attributes[opt]
-/// decl-specifier-seq abstract-declarator[opt] attributes[opt]
+/// attribute-specifier-seq[opt] decl-specifier-seq declarator attributes[opt]
+/// attribute-specifier-seq[opt] decl-specifier-seq declarator attributes[opt]
/// '=' assignment-expression
+/// attribute-specifier-seq[opt] decl-specifier-seq abstract-declarator[opt]
+/// attributes[opt]
+/// attribute-specifier-seq[opt] decl-specifier-seq abstract-declarator[opt]
+/// attributes[opt] '=' assignment-expression
///
Parser::TPResult Parser::TryParseParameterDeclarationClause() {