Re: Feature idea: Git hook for pre-checkout

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 30, 2025, 17:25 UTC
Message-ID: <xmqqy0ysfc2t.fsf@gitster.g>
In-Reply-To: <Z5rhXrkbhINwFDXT@tapette.crustytoothpaste.net>

"brian m. carlson" <sandals@crustytoothpaste.net> writes:

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> On 2025-01-29 at 10:49:15, Mike Weltevrede wrote:
>> Good morning,
>> 
>> I had an idea for a feature in Git. I am not sure if this is the
>> correct channel, but I could not find anything else. If not, could you
>> please let me know the best way to submit this?
>
> This is the appropriate place to make feature requests.

Yes, indeed.

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> I don't think this is likely to be adopted.  We intentionally don't
> place a lot of restrictions on local actions, ...
> In addition, this change wouldn't really be very effective, ...
> `git push origin my-feature:refs/features/foo`.
> It also sounds like you're trying to implement a policy decision on the
> local system, which is the wrong place, as the Git FAQ outlines[0]:

Thanks for raising all good points.

Even though I am negative on adding a hook that does not satisify any of the "5 valid reasons" [*], this one squarely satisifies (1). But I fully agree with you that it is ineffective as a policy enforcement mechanism, and a local hook should not be used as such.

Having said that, giving reminders locally and early to help users avoid making mistakes that will be pointed out at the remote at reception time via their pre-receive hook, only when the user does "git push", can still be a good friction reducer.

So I am not opposed to an idea to have a mechanism that reminds the users of project-specific naming convention of branches and files (think: cross platform projects that have participants from case insensitive filesystems) when they create such a thing anew locally, especially the project would have a rejection mechanism when their participants try to push their changes that adds such a thing.

Here, however, again I agree with you that a pre-checkout hook will not be an effective mechanism to give that reminder. The mechanism must sit at the ref API layer in order to vet all ways of creating (or renaming) a ref in order for to be effectively restrict branch names. For pathnames, the mechanism must sit at the cache API layer to tell add_to_index() what names are problematic.

Thanks.

[Reference]

*1* There may be slightly updated versions of this in the archive, but https://lore.kernel.org/git/7vbq7ibxhh.fsf@gitster.siamese.dyndns.org/ is one of them.