diff --git a/clang/include/clang/Analysis/Analyses/ThreadSafetyTraverse.h b/clang/include/clang/Analysis/Analyses/ThreadSafetyTraverse.h
index 811feaca016b..3692b75e7a2f 100644
--- a/clang/include/clang/Analysis/Analyses/ThreadSafetyTraverse.h
+++ b/clang/include/clang/Analysis/Analyses/ThreadSafetyTraverse.h
@@ -433,6 +433,7 @@ public:
 #include "ThreadSafetyOps.def"
 #undef TIL_OPCODE_DEF
     }
+    llvm_unreachable("invalid enum");
   }
 };