Check if an IdentifierInfo* is null when the FunctionDecl isn't a simple C function.

Fixes <rdar://problem/12355298>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@164988 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 7498d34..81be8bf 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -5510,8 +5510,12 @@
   } else if (CallExpr *CE = dyn_cast<CallExpr>(e)) {
     if (CE->getNumArgs() == 1) {
       FunctionDecl *Fn = dyn_cast_or_null<FunctionDecl>(CE->getCalleeDecl());
-      if (Fn && Fn->getIdentifier()->isStr("_Block_copy"))
-        e = CE->getArg(0)->IgnoreParenCasts();
+      if (Fn) {
+        const IdentifierInfo *FnI = Fn->getIdentifier();
+        if (FnI && FnI->isStr("_Block_copy")) {
+          e = CE->getArg(0)->IgnoreParenCasts();
+        }
+      }
     }
   }