Sanity checks are performed on includes and excludes in precious.toml

[rafl]

To address the same concern as the external tool https://github.com/oalders/ppath/.

When using the git version control system, this can be achieved reasonably fast with a combination of calls to git ls-files and git check-ignore, as illustrated by a prototype implementation I wrote (https://houseabsolute.slack.com/archives/C2M2EM0LX/p1670442201584039 if you're on this slack - ask for an invite if you're curious).

We want:

• there to exist a new command to check a precious config file for the issues ppath is trying to address
  • the new command to exit with a non-zero status when any issues are found
• these checks to be performed by default on every tidy/lint run
  • any violation of the checks to be merely a warning
  • the checks to be fast
    • it's OK to be VCS-specific and to not initially support all VCSs that precious aims to support

[oalders]

I'm not sure that git ls-files can easily be used to check the include/exclude patterns in the config.

The config appears to be using file glob patterns. git ls-files would be using gitignore matching patterns. There is some overlap here, but there are some significant differences as well.

[oschwald]

I believe ignore::gitignore is used for the exclude paths, which, as the name suggests, uses the gitignore glob format.

[autarch]

I started working on this today but I realized that I don't think we should always lint all excludes. Consider a case like a Rust project, where I'll always exclude the target dir. It's quite possible for the repo to be in a state where that directory doesn't exist, and that's fine.

I suspect this applies to other non-global excludes as well.

I do think it'd make sense to validate that the include matches something, however.

[autarch]

One option for excludes would be to optionally warn when they don't match anything, but it definitely shouldn't be an error. And you probably wouldn't want this sort of warning running in CI, since it'd be very likely to be a false positive. But it might be handy for manually reviewing your config from time to time.