[PATCH] D79400: [CMAKE] Fix build failure when source directory is read only

[Scott Linder via Phabricator via llvm-commits]

scott.linder added a comment.

I'd be interested in the answer concerning why we need to avoid `git rev-parse HEAD`; it seems like the cleanest solution is to just always check if `git rev-parse HEAD` changes to determine whether to regenerate the header.

If that is not feasible for some reason, I would lean towards your option (2), but I think more is needed in this patch to ensure the generation script is always run, right? How does //removing// a dependency cause the target to be executed each build? Don't we need to detect the case where `.git/logs/HEAD` is missing and make the target depend on `ALL` or whatever the CMake notion of "always out of date" is? We will also need to be OK with the regression in what happens when you do a `repo` checkout in a read-write context, as that will always run the script whereas before it would have the same behavior as a normal checkout. I don't know what the implication of all of these changes are, though.


Repository:
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https://reviews.llvm.org/D79400