Linked gitdirs without commondir file (submodules) don't resolve git dir

[davidkna]

Duplicates

• I have searched the existing issues

Current behavior 😯

This causes starship/starship#4266

If a linked git dir does not contain a commondir file, it will be ignored:

gitoxide/git-discover/src/is.rs

Lines 43 to 48 in 47724c0

	let common_dir = private_git_dir.join("commondir");
	let common_dir = crate::path::from_plain_file(&common_dir)
	.ok_or_else(|| crate::is_git::Error::MissingCommonDir {
	missing: common_dir.clone(),
	})?
	.map_err(|_| crate::is_git::Error::MissingCommonDir { missing: common_dir })?;

I tried replacing it with this, but that caused some test failures I wasn't sure how to best resolve:

            let common_dir = private_git_dir.join(common_dir);
                .and_then(Result::ok)
                .map(|cd| private_git_dir.join(cd))
                .unwrap_or_else(|| private_git_dir.clone());

This means that for git submodules, the git dir ends up resolving to mysubmodule/.git instead of .git/modules/mysubmodule.

Expected behavior 🤔

Git submodule .git-files resolve to the referenced location.

Steps to reproduce 🕹

1. Attempt to open a submodule directory
2. Inspect .git_dir()

[Byron]

Thanks a lot! It would have been lucky if this would have worked out of the box, as it was never tested.

This should change though, and I plan to remedy this soon, hoping that a test or two with submodules can help making the necessary adjustments without having to support submodules fully. Let's see :D.