Linux: "LLVM Profile Error" written to stderr when running unit tests

[PathogenDavid]

The following message is printed to stderr many times after running unit tests:

LLVM Profile Error: Failed to write file "default.profraw": Permission denied

Searching this error does not reveal anything particularly relevant or useful at a glance, everything's about some setting in Xcode.

This doesn't have any negative impact on actual Biohazrd operation, but it's annoying. Also in theory it might actually write this file to undesired places if it was possible. (It's not clear why permission is being denied in this case.) Additionally if Clang is actually putting extra effort into capturing some sort of profiling data we don't want it to do that.

TODO: Determine if this affects generators too. (Right now I'm only running the tests.)

[PathogenDavid]

lol, like I was saying.

Also the reason the permission is getting denied is probably because we have multiple instances of Clang/LLVM running in the same process and only one of them gets the lock on the file.

With that I realized I never searched for just default.profraw on its own. Searching that brings up all kinds of weird issues. It's not super clear where the fault lies. Is libclang trying to create a PGO file for the library we're processing or did I build libclang with PGO enabled?

[PathogenDavid]

This actually isn't coming from libclang-pathogen because I accidentally ran all the tests without it and something was still trying to write them. I'm running the .NET preview, so maybe that's in? If so, I'm surprised there aren't issues about it on the runtime repo.

[PathogenDavid]

Yup, it was the .NET Preview, more details here: dotnet/sdk#18829