Exactly. -Werror for the normal make target is problematic.

But -Werror for a dev target that e.g. CI uses to compile-test pull requests on known toolchains and distros that you explicitly intend to support is useful. The alternative would be tons of effort to skip -Werror but still have CI flag that pull request that introduces new warnings. Just having the build fail because -Werror is far simpler and less fragile.

Yeah, use it with your CI or test suite. Also `-Wd` for Python, and I'm sure there are equivalents for other toolchains/languages.

IMHO it's similar to the robustness principle/Postel's law: "be conservative in what you send, be liberal in what you accept". Your build should pass without warnings on your system, but your build system should allow warnings on your customer's system.