[libcxx-commits] [libcxx] [libcxx] [modules] Fix relative paths with absolute LIBCXX_INSTALL_MODULES_DIR (PR #85756)

[Martin Storsjö via libcxx-commits]

mstorsjo wrote:

> @mstorsjo Thanks for the quick response. I'll try to sync w/ @petrhosek to see if he knows a way to work around the issue.

Thanks, that's appreciated.

It's probably not hard, we'd just need to use a dummy `/` as the base directory, if `CMAKE_INSTALL_PREFIX` is empty (which would mimic what happened before anyway), so that `file(RELATIVE_PATH` doesn't error out, even if the output is seemingly bogus.

https://github.com/llvm/llvm-project/pull/85756