I confirm that it is a problem with 7zip, which is not preserving symlinks by default. Thanks for pointing to it.
The reason why this commit "broke" it for us, is because it introduced symlinks on Windows.
I'm still not sure that using symlinks on Windows is a good idea, given how poorly they are supported by the ecosystem.

Note, there's a bug caused by these changes: LLVM bug 51692
TLDR: in Github Action (Windows) environment compiler builds "successfully", but links are broken and no copy is done.

Thanks for the report. It seems the thing to do is to modify the warning so that variables marked extern are not candidates for this warning. I will make a new commit with that modification unless there are other suggestions.

One more false-positive:

void foo() {
  extern int yydebug;
  yydebug = 1;
}

Would be good to have it merged to 11.0.

I've run it through 1.6M tests on x86 (-O3) and found nothing. This makes me pretty sure that my run will not find anything new in reasonable time.

In D36581#838767, @niravd wrote:

I also have a patch that more aggressively causes invalidation-based assertions where latent bugs may lie; I think it'll catch the lion share of the latent bugs.

I still see 19 fails with current patch. All the remaining fails that I have are reduced and attached to 32284 as third attachment.

Thanks for the fix, it works.

Your comment in include/llvm/IR/InstrTypes.h in line 1137 is undeniably
nice, but it causes a warning (or an error when building with "-Wall"):