Re: BUG: git worktree add directory-path fails due to over-aggressive disallowing of worktrees with same suffix
To
Cameron Gunnin
Cc
git@vger.kernel.org
From
Eric Sunshine
See Also
Prev
Date
2019-02-12 22:44:41 UTC
On Mon, Feb 11, 2019 at 6:50 PM Cameron Gunnin
<cameron.gunnin@synopsys.com> wrote:
> The bug:
>   cd unique-path-1
>   git --git-dir=../worktree-test-repo/.git worktree add subdir branch1
>   cd ../unique-path-2
>   git --git-dir=../worktree-test-repo/.git worktree add subdir branch2
>   # FAILS WITH: fatal: 'subdir' is a missing but already registered worktree; use 'add -f' to override, or 'prune' or 'remove' to clear
>
> This appears to have been introduced by the following commit:
>       worktree: disallow adding same path multiple times
>
> The fix, I think, should be applied to builtin/worktree.c to the
> validate_worktree_add method. After finding a worktree that matches
> the suffix (via find_worktree), it should check that the absolute
> path of the found worktree is the same as the absolute path of the
> worktree being added, and allow the add when they are different. Or,
> perhaps there should be a way to invoke 'find_worktree' such that it
> only finds absolute path matches.

When crafting cb56f55c16 (worktree: disallow adding same path multiple
times, 2018-08-28), I flip-flopped between two implementations: (1)
using find_worktree(), and (2) manually scanning the worktree list
with absolute path comparison. The latter approach, would not have
suffered from this problem. The one ugly bit of the manual scan was
that it was a bit too cozy with the underlying worktree
implementation, so I eventually went with the find_worktree() approach
despite its obvious drawback of doing suffix matching (though, I
didn't feel particularly comfortable with the decision).

A likely reasonable approach to fixing it would probably be to
introduce new worktree API to find a worktree without magic suffix
matching (i.e. literal absolute path matching) which would avoid
having to imbue the higher-level "git worktree" command with that
low-level knowledge, and then take advantage of that new API.