Add flag to clone a git repository recursive

[sectore]

to support git submodules.

I came across that issue while trying to update https://github.com/domenkozar/hie-nix to latest HIE. Because HIE is using submodules now, stack2nix was thrown an error about missing sources of submodules defined in stack-8.2.1.yaml or stack-8.2.1.yaml.

This PR will fix that issue.

[domenkozar]

@jmitchell do you think we could merge this?

[domenkozar]

Actually, I think there's a problem. We are first cloning git repository with submodules for master HEAD, then we checkout to another branch. But if another branch has different submodules, this will fail.

@sectore can you make submodule usage explicit command after checkout has been done?

[sectore]

can you make submodule usage explicit command after checkout has been done?

@domenkozar Which git command do have in mind? Some other command instead of using git clone _uri_ --recursive _dir_?

[domenkozar]

Yes - git submodule update --init --recursive

[sectore]

@domenkozar Would git clone --recurse-submodules {GIT-REPO} {DIR} work as well?

This is equivalent to running git submodule update --init --recursive immediately after the clone is finished.

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

[sectore]

@domenkozar Or did you mean to run that git submodule ... command right after running git checkout https://github.com/sectore/stack2nix/blob/f95772fc762c5a0d9e3caded6ca5b98711fb85ad/src/Stack2nix/External/VCS/Git.hs#L38 ? I guess the latter, right?

[sectore]

@domenkozar 09a7af0 (not tested locally)

[sectore]

@jmitchell Friendly ping: Are you happy with that PR ^ or do you miss something? It would be great to have that PR in master... Thanks!

[domenkozar]

There is some kind of a bug that causes domenkozar/hie-nix#13 (comment) - I will investigate tomorrow.

[puffnfresh]

Should this just be the default behaviour?

[domenkozar]

OK there's no bug in particular with this PR, but I've opened #103

[jmitchell]

Should this just be the default behaviour?

Unless there's some way we discover this could break other projects, that sounds good to me.

[domenkozar]

Mainly need to check if it has performance implications.

[domenkozar]

Couldn't find a reason not to do handle submodules by default, so I opened #108

[domenkozar]

Thank you @sectore for this work!