git: added Clone.NoCheckout option

[Nhoya]

Hi, i was wondering if was possible to reproduce the -n option of git clone

[mcuadros]

Should be that easy as skip this line: https://github.com/src-d/go-git/blob/v4.0.0/worktree.go#L181

[rykov]

@mcuadros I didn't find where Repository's clone func calls Checkout on the worktree that you've linked.

Do you think that it could be implemented by adding a flag to CloneOptions that would disable this section of Repository's clone even if r.wt != nil?

https://github.com/src-d/go-git/blob/v4.0.0/repository.go#L452-L478

[rykov]

Something like this: master...rykov:master

[rykov]

@mcuadros I've taken another look at the documentation for git-clone and I think the changes that I've made on my fork follow the functionality closer than putting a condition just around Reset.

Here's what the docs say for --recurse-submodules:

This option is ignored if the cloned repository does not have a worktree/checkout (i.e. if any of --no-checkout/-n, --bare, or --mirror is given)

https://git-scm.com/docs/git-clone#git-clone---recurse-submodulesltpathspec

I'll add some tests and submit this as a PR

[Nhoya]

Pretty interesting, can you please provide an example usage?

[rykov]

@Nhoya So the behavior is similar to git clone --bare, in that the worktree is not created. However, with -n option, the metadata is still placed under the .git subdirectory, rather than in root.

Here's a modification of the basic example from the README with this flag enabled:

Info("git clone -n https://github.com/src-d/go-git")

_, err := git.PlainClone("/tmp/foo", false, &git.CloneOptions{
    URL:        "https://github.com/src-d/go-git",
    Progress:   os.Stdout,
    NoCheckout: true,
})

CheckIfError(err)

[Nhoya]

Hi and thanks for the answer

So retrieving commits with

r, _ := git.Clone(memory.NewStorage(), nil, &git.CloneOptions{
    URL:        "https://github.com/src-d/go-git",
    Progress:   os.Stdout,
    NoCheckout: true,
})
ref, _ := r.Head()
cIter, _ := r.Log(&git.LogOptions{From: ref.Hash()})

commits := ""
_ = cIter.ForEach(func(c *object.Commit) error {
    commits += fmt.Sprintf("%s", c.Author)
    return nil
})

is still possible?