[Parser] Fix look ahead after EOF while parsing objc message and lambdas

[bruno]

Summary

If a closing ')' isn't found for a macro instantiation inside a '[',
the next token is EOF, this leads to crashes if we try to look ahead of
that. This could be triggered whenever trying to parse lambdas or objs
message expressions.

[bruno]

Ping!

[bruno]

Ping!

[doug.gregor]

LGTM, sorry for the delay!

[bruno]

Thanks Doug!

Committed r271314

lib/Parse/ParseExprCXX.cpp

          && Tok.is(tok::l_square)
          && "Not at the start of a possible lambda expression.");
 
-  const Token Next = NextToken(), After = GetLookAheadToken(2);
+  const Token Next = NextToken();
+  if (Next.is(tok::eof)) // Nothing else to lookup here...
+    return ExprEmpty();
 
+  const Token After = GetLookAheadToken(2);
   // If lookahead indicates this is a lambda...
   if (Next.is(tok::r_square) ||     // []
       Next.is(tok::equal) ||        // [=

test/Parser/objcxx11-messaging-and-lambda.mm

+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+
+#define OBJCLASS(name) // expected-note {{macro 'OBJCLASS' defined here}}
+
+class NSMutableData;
+
+NSMutableData *test() { // // expected-note {{to match this '{'}}
+  NSMutableData *data = [[[OBJCLASS(NSMutableDataOBJCLASS( alloc] init] autorelease]; // expected-error {{unterminated function-like macro invocation}} \
+  // expected-error {{expected ';' at end of declaration}}
+  return data;
+} // expected-error {{expected expression}} expected-error {{expected '}'}}