feat: Support install directly from git repo

[NobodyXu]

Fixed #3

[passcod]

Generally good, some notes and questions

[passcod]

Can be for a future improvement, but would be useful to consider supporting some syntax or options for:

• Branches/refs other than default
• Subpaths in the repo

[NobodyXu]

I think we can support that by using fragment, e.g.

https://github.com/cargo-bins/cargo-binstall#branch=...#subpath=...

or maybe using query:

https://github.com/cargo-bins/cargo-binstall?branch=...?subpath=...

Not sure which one is more compatible with git url, I need more advice on this.

[passcod]

I think doing whatever cargo and/or npm does is a good default?

[NobodyXu]

Yeah and that will be compatible with cargo-install:

       --git url
           Git URL to install the specified crate from.

       --branch branch
           Branch to use when installing from git.

       --tag tag
           Tag to use when installing from git.

       --rev sha
           Specific commit to use when installing from git.

so we would have to at least support --branch/--tag/--rev just like cargo-install.

I think cargo-install finds the Cargo.toml by the package name, so we can also do that in cargo-binstall.

[NobodyXu]

@Byron I tried searching for how to checkout branch in gitoxide but only found this GitoxideLabs/gitoxide#358 which uses low-level APIs.

I also checked gix::Repository but I also failed to find one, seems like only way is to dive into the low-level APIs of gix to do this.

[Byron]

Yes, indeed, the combination of choosing a refspec that fetches the desired branch and checking out its tree afterwards is how --branch would be implemented. The question of how to deal with the implementation's limitations would still have to be answered though.

Though I didn't know there's a filter in gix.

I don't know what filter means in this context. Feel free to ignore if everything is clear to you though.

I might need to take a look at PRs linked with rust-lang/cargo#11813 to see how they accomplish this.

cargo still performs checkouts using git2, and it's what I will be working to change from now on.

[NobodyXu]

Yes, indeed, the combination of choosing a refspec that fetches the desired branch and checking out its tree afterwards is how --branch would be implemented.

Thanks for confirmation of this!

This goes by the big caveat that filters aren't applied and that it will panic on submodules (not implemented) - checking things out is generally not ready yet even though it works well enough for some cases.

Well that's unfortunate.
Our goal here is to have the same behavior as cargo-install when --git is passed.
I'm not sure whether it clones submodules though.

cargo still performs checkouts using git2, and it's what I will be working to change from now on.

Thanks for the info, I will keep track of the adoption of gitoxide in cargo

[NobodyXu]

I tried

                prepare_fetch =
                    set_fetch_refspec(prepare_fetch, format!("+refs/heads/main:refs/remotes/origin/{branch}"));

fn set_fetch_refspec(prepare_fetch: clone::PrepareFetch, refspec: String) -> clone::PrepareFetch {
    prepare_fetch.configure_remote(move |mut remote| {
        remote.replace_refspecs([refspec.as_bytes()], remote::Direction::Fetch)?;
        Ok(remote)
    })
}

but somehow it still clones main.

[NobodyXu]

It might be too hard to get everything done in one PR, while gix doesn't support checking out specific branch/tag/rev at clone.

I will open a new tracking issue for this.

[NobodyXu]

Opened tracking issue #1165 for this.