diff --git a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
index 77287ec45972d..0d9252a55d280 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
@@ -104,6 +104,7 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
       return builder.createBoolToInt(value, dstTy);
     if (mlir::isa<cir::BoolType>(dstTy))
       return value;
+    llvm_unreachable("Can only promote integer or boolean types");
   }
 
   //===--------------------------------------------------------------------===//