Re: [bug report] git diff --relative not doing well with worktree in hooks

From: Eric Sunshine <sunshine@sunshineco.com>
Date: May 31, 2024, 21:42 UTC
Message-ID: <CAPig+cT1pTkKd1A0o_qjP+Oyx+zyCevV8EAg5Ub9guAyd3UjgA@mail.gmail.com>
In-Reply-To: <CADg0FA_9shzJKN=dBfnavu5eTDNhbz=g0WP2sehAjSqHP4WFkA@mail.gmail.com>

On Fri, May 31, 2024 at 7:38 AM Antoine Bolvy <antoine.bolvy@gmail.com> wrote:

Show 16 quoted lines

> I noticed a weird behavior when using git diff --relative with worktrees and
> hooks. When called from a pre-commit hook from a worktree, the relative option
> has no effect.
>
> [main tree] Displays
> ```
> /home/arch/git/awfus/hook-repro/test/folder
> bar
> ```
> [in worktree] Displays
> ```
> /home/arch/git/awfus/hook-repro/worktree/folder
> folder/foo
> ```
> The path is no longer show relative. This causes issues with more complex
> scripts.

I'm not sure there's a satisfactory resolution here. Your hook is running afoul of the environment variables Git sets up when the hook is run outside of the "main" worktree.

If you change your hook from:

    #!/bin/bash
    cd folder || exit
    pwd # display the current working directory
    git diff --cached --relative --name-only

to:

    #!/bin/bash
    cd folder || exit
    pwd # display the current working directory
    unset $(git rev-parse --local-env-vars)
    git diff --cached --relative --name-only

then it works as expected.

The relevant portion from the "githooks" manual page is:

    Environment variables, such as GIT_DIR, GIT_WORK_TREE, etc., are
    exported so that Git commands run by the hook can correctly locate
    the repository. If your hook needs to invoke Git commands in a
    foreign repository or in a different working tree of the same
    repository, then it should clear these environment variables so
    they do not interfere with Git operations at the foreign
    location. For example:

        local_desc=$(git describe)
        foreign_desc=$(unset $(git rev-parse --local-env-vars); git -C
../foreign-repo describe)