In 'delete []', the '[]' never starts a lambda. Update a FIXME with a standard reference and add a test.

llvm-svn: 161604
diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index 592a3cc..afac257 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -2403,10 +2403,14 @@
   // Array delete?
   bool ArrayDelete = false;
   if (Tok.is(tok::l_square) && NextToken().is(tok::r_square)) {
-    // FIXME: This could be the start of a lambda-expression. We should
-    // disambiguate this, but that will require arbitrary lookahead if
-    // the next token is '(':
-    //   delete [](int*){ /* ... */
+    // C++11 [expr.delete]p1:
+    //   Whenever the delete keyword is followed by empty square brackets, it
+    //   shall be interpreted as [array delete].
+    //   [Footnote: A lambda expression with a lambda-introducer that consists
+    //              of empty square brackets can follow the delete keyword if
+    //              the lambda expression is enclosed in parentheses.]
+    // FIXME: Produce a better diagnostic if the '[]' is unambiguously a
+    //        lambda-introducer.
     ArrayDelete = true;
     BalancedDelimiterTracker T(*this, tok::l_square);