cargo-llvm-cov: init at 0.5.0

[CobaltCause]

Description of changes

This packages cargo-llvm-cov, a tool for generating code coverage reports using built-in features of recent Rust toolchains.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.11 Release Notes (or backporting 22.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[winterqt]

Thanks for the PR, but this is a dupe of #185183.

I'd appreciate it if you could go over that PR if you have any suggestions or comments, plus test it, if you'd like :)

Thanks again, and I hope you contribute more to Nixpkgs in the future!

[CobaltCause]

Oh lol I should've checked for that. They also appear to have gotten the tests working while I just ignored them, which is definitely better. Thanks!

[winterqt]

They also appear to have gotten the tests working while I just ignored them

I just used a less verbose method of disabling just those broken tests there, they're still broken since we don't ship llvm-tools-preview.

[CobaltCause]

If you re-open this PR, I actually just reworked it in a way where all the tests run and pass properly: CobaltCause@1415724

[CobaltCause]

Note: refactoring this to use fetchCrate instead of fetchFromGithub causes the tests to stop working.

[winterqt]

Yes, this is because Cargo skips the fixture directories when packing for publishing, since it thinks they're unrelated crates.

I'd love to reopen this, but...

[CobaltCause]

Oh, yeah I did force-push to fix the tests. Should I re-open as a new PR?

[winterqt]

Go for it -- there's one change I want to try to not have to add the Cargo.lock, but other than that it should be good to go :)

[CobaltCause]

Done: #197478