diff --git a/clang/lib/AST/Interp/ByteCodeExprGen.cpp b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
index 8f53f0e1d6f5b..be2c48456b5b1 100644
--- a/clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -147,6 +147,7 @@ bool ByteCodeExprGen<Emitter>::VisitCastExpr(const CastExpr *CE) {
   default:
     assert(false && "Cast not implemented");
   }
+  llvm_unreachable("Unhandled clang::CastKind enum");
 }
 
 template <class Emitter>