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 '[]'.

llvm-svn: 154369

clang/lib/Parse/ParseInit.cpp

@@ -211,6 +211,11 @@ ExprResult Parser::ParseInitializerWithPotentialDesignator() {
     //   [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);