Implement C++0x nullptr.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@71405 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 77a25f6..0d38dd2 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1377,6 +1377,10 @@
     return true;
   }
 
+  // C++0x nullptr_t is always a null pointer constant.
+  if (getType()->isNullPtrType())
+    return true;
+
   // This expression must be an integer type.
   if (!getType()->isIntegerType())
     return false;