mintsuki wrote: > Add a run line like `RUN: %clang -### -Werror ... 2>&1 | FileCheck %s`. If `%clang` reports a warning (turned to an error due to -Werror), the exit code will be 1. This warning does not return 1 with `-Werror` though. https://github.com/llvm/llvm-project/pull/147952