Fix an unused variable warning in release builds and make the
assert-less codepath marginally more efficient.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@128472 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 8125ce1..c023cd3 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -1074,9 +1074,9 @@
         const Type *ClassType
           = S.Context.getTypeDeclType(Method->getParent()).getTypePtr();
         FromType = S.Context.getMemberPointerType(FromType, ClassType);
-      } else if (UnaryOperator *UnOp
-                 = dyn_cast<UnaryOperator>(From->IgnoreParens())) {
-        assert(UnOp->getOpcode() == UO_AddrOf &&
+      } else if (isa<UnaryOperator>(From->IgnoreParens())) {
+        assert(cast<UnaryOperator>(From->IgnoreParens())->getOpcode() ==
+               UO_AddrOf &&
                "Non-address-of operator for overloaded function expression");
         FromType = S.Context.getPointerType(FromType);
       }