Treat warnings as errors all over LLDB when enabled. Defaults to OFF.
LLVM_ENABLE_WERROR affects the entire build tree. If another subproject causes a warning the build fails. In a way, you are right that this is sufficient, because the no-warnings policy seems to work well upstream.
The issue I was trying to solve is, that we can't use the setting with some external subprojects, because they are not strictly warning free. But then it may be better to have downstream. I agree.