Re: git aliases and GIT_PREFIX

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Nov 2, 2021, 14:26 UTC
Message-ID: <nycvar.QRO.7.76.6.2111021520370.56@tvgsbejvaqbjf.bet>
In-Reply-To: <2e328484-d0e3-8801-61da-07544cc93eef@gmail.com>

Hi Federico,

On Thu, 28 Oct 2021, Federico Kircheis wrote:

Show 9 quoted lines

> today I reported what I believed to be a bug on
>
>  https://github.com/git-for-windows/git/issues/3496
>
> and learned about GIT_DIR when working with aliases and git worktree.
>
> It's annoying that GIT_DIR it is defined only if (as far as I've understood)
> working from a worktrees or submodule, as it does not seem to be related to
> those type of repositories.

To clarify: `GIT_DIR` is set when executing an alias in a worktree other than the primary one (and probably also in submodules), but not when executing in a primary worktree.

> This is also irritating because apparently working aliases breaks when being
> executed from those repositories.

To clarify: an alias that wants to switch to a different repository and execute Git commands there works well in a primary worktree. But when you switch to a different repository while executing an alias from a secondary worktree, it will fail because of `GIT_DIR` having been set.

> I believe it would be better if GIT_DIR it's either always set or never
> (could someone enlighten me why the variable is needed in first place?).

The fact that `GIT_DIR` is not set when calling an alias in a primary worktree suggests that the behavior in secondary worktrees is not by design. We should therefore be able to stop setting it there.

The question is: what code is responsible for setting it only in some circumstances but not others?

Federico, do you have any experience in debugging C code? If so, it would be good if you could take a crack at investigating this.

Ciao, Johannes