diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index de48b15645b1a..f4246c5e8f68e 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -1019,7 +1019,7 @@ CodeGenFunction::emitFlexibleArrayMemberSize(const Expr *E, unsigned Type,
   FAMSize = Builder.CreateIntCast(FAMSize, ResType, IsSigned);
   Value *Res = FAMSize;
 
-  if (const auto *DRE = dyn_cast<DeclRefExpr>(Base)) {
+  if (isa<DeclRefExpr>(Base)) {
     // The whole struct is specificed in the __bdos.
     const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(OuterRD);