feat: nixpkgs-vet --version

[dtomvan]

This PR simply adds the clap-flag version, so that -V or --version can be passed to get the current version of nixpkgs-vet.

Why: to make versionCheckHook work. Some effort is being made right now to package nixpkgs-vet inside of nixpkgs (here) and versionCheckHook is a good practice to allow r-ryantm to test its updates, and a way to make sure that a build only succeeds when the output binary has at least some basic functionality.

[philiptaron]

Thanks! Could you add a test using versionCheckHook to the package build?

[philiptaron]

Huh.

Process completed with exit code 143.

No error logs.

Not great.

[dtomvan]

Thanks! Could you add a test using versionCheckHook to the package build?

Oh, I'm sorry. I forgot the in-tree package.nix, and only thought about nixpkgs...

With your commit, if I add doInstallCheck = true; I get:

Executing versionCheckPhase
Did not find version 0.1.4 in the output of the command /nix/store/cd833kis53ajzk2wjkwdqkimrqx94s07-nixpkgs-vet-0.1.4/bin/nixpkgs-vet --help
Program to check the validity of pkgs/by-name

This CLI interface may be changed over time if the CI workflow making use of it is adjusted to
deal with the change appropriately.

Exit code:
- `0`: If the validation is successful
- `1`: If the validation is not successful
- `2`: If an unexpected I/O error occurs

Standard error:
- Informative messages
- Detected problems if validation is not successful

Usage: nixpkgs-vet --base <BASE> <NIXPKGS>

Arguments:
  <NIXPKGS>
          Path to the main Nixpkgs to check. For PRs, set this to a checkout of the PR branch

Options:
      --base <BASE>
          Path to the base Nixpkgs to run ratchet checks against. For PRs, set this to a checkout of the PRs base branch

  -h, --help
          Print help (see a summary with '-h')

  -V, --version
          Print version
Successfully managed to find version 0.1.4 in the output of the command /nix/store/cd833kis53ajzk2wjkwdqkimrqx94s07-nixpkgs-vet-0.1.4/bin/nixpkgs-vet --version
nixpkgs-vet 0.1.4

So, that seems correct, no? I suspect some other tests are failing then, like /nix/store/8adxcgysy2jprpr6xpxpxv1l0f9qnn55-test-nixpkgs-vet-with-nix-2.25.5.drv, since running those in parallel takes a lot of memory...

Locally, with 16 GB of RAM, and almost filling all of my 20GB swap, everything passed:

result -> /nix/store/ivg6pwfr1b6c589189ir21rzll1zz74r-auto-pr-update
result-2 -> /nix/store/cd833kis53ajzk2wjkwdqkimrqx94s07-nixpkgs-vet-0.1.4
result-3 -> /nix/store/72jrhrxvxma41sz4l3vzn1b86gqkbsns-ci
result-4 -> /nix/store/6ilkcbaxdhg3v43yxm5i302r06fyy3qq-test-nixpkgs-vet-with-nix-2.24.12
result-5 -> /nix/store/wp0plccpzv3nbxr6fm44jf6k2zm07bda-test-nixpkgs-vet-with-nix-2.25.0pre20241101_2e5759e3
result-6 -> /nix/store/k2vhzj0c36q6f5m8a77lacbpvhhjzzw9-test-nixpkgs-vet-with-lix-2.91.1
result-7 -> /nix/store/c4r0r93j5523dpbyggdgzyrjv6wqjmdr-test-nixpkgs-vet-with-nix-2.25.5
result-8 -> /nix/store/lqk0h3cizhkaadm5axwgfwyxkrq2wi6j-test-nixpkgs-vet-with-nix-2.3.18
result-9 -> /nix/store/11ij3v009r8hfpxbh8xbpsj2cq16zzh3-nix-shell
result-10 -> /nix/store/0w9xvplihlc6nlf7i89q0dwv9qa6zc5k-treefmt-check

[dtomvan]

Cachix sets max-jobs to auto. I'm pretty sure this leads to Github killing the test midway due to OOM. So I think the following YAML snippet will allow all tests to be ran one-by-one in CI, if desired.

with:
  extra_nix_config: |
    max-jobs = 1