@acowley, thanks for your PR! By analyzing the history of the files in this pull request, we identified @anderspapitto, @periklis and @copumpkin to be potential reviewers.

I noticed similar behaviour with #25352, not sure if there's a reason for it but that's set in the library id of libclang.

$ otool -D result/lib/libclang.dylib
result/lib/libclang.dylib:
@rpath/libclang.dylib

I don't have any strong feelings regarding fixing it here or there. This is where it bit me, but changing the clang derivation is fine by me. I have another PR open to add something to llvmPackages, but I don't think that PR will force much of a rebuild. Changing libclang.dylib would do so, afaics, so we could postpone that until something else comes up to bundle them together... though I don't know how we'd avoid losing track of wanting to make this change.

Relevant: #21624

Previous versions of libclang have an absolute path for the library id, so I don't expect any issues if we rewrite it. I'm testing the clang changes to see if that fixes the problem.

@domenkozar: fixDarwinDylibNames doesn't seem to fix this because the problem is in linking the binaries incorrectly. It looks like rtags is doing something weird with CMake changing rtags in weird ways. Either way this patch does fix rtags for me while fixDarwinDylibNames doesn't change anything.

@matthewbauer the fixDarwinDylibNames needs to run on clang to fix the library id there.

This commit LnL7@972631c fixes the issue, but the clang builds keep timing out 😕 http://hydra.nixos.org/eval/1358432. I would prefer to make sure everything looks good before pushing that to staging.

@LnL7 This is dragging out a bit. If there isn't much of a hue and cry around nixpkgs due to the libclang name, the benefits of the right fix (i.e. what you've done) may not be a whole lot more than fixing rtags. Can we apply this spot fix now and hope that the timeout situation gets resolved at some point in the future allowing you to more confidently push the right fix?

Agreed, I didn't expect testing my changes to stall this long. This is also not a problem when lib clang is fixed, it just becomes a noop.