Re: Bug: git branch -D can be used to delete branch which is currently checked out

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 10, 2016, 17:40 UTC
Message-ID: <xmqqvb4udyf9.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <CE5AE06C-0909-414E-B901-7CCF3A259465@gmail.com>

Marcus Kida <marcus.kida@gmail.com> writes:

Show 7 quoted lines

> Testes on: 
>
> Mac OS X 10.11.3 (El Capitan) using Git 2.6.4
>
> Issue:
>
> git branch -D can be used to delete branch which is currently checked out

There are other limitations a filesystem that is incapable of differentiating two files with names that are only different in case imposes on your use of Git, e.g.

 - "git fetch origin", when the origin repository has two tags 'v1'
   and 'V1', may not let you have both of these tags locally;

 - "git checkout Another", when the branch you have is 'another',
   may check it out instead of complaining (replace "checkout" with
   any other command that let you use a refname to specify an object).

It is a possibility to teach the files backend of refs API that some filesystems are case insensitive and do something special about them, but I think in the longer term a more productive solution would be to use the upcoming "pluggable ref backend" subsystem and either

 - use a backend that is not the "files" backend (e.g. lmdb backend,
   or the tree-object based backend);

 - add a variant of "files" backend but encodes the refnames in a
   way that is safe on case insensitive filesystems.

That way, those on platforms with case insensitive filesystems do not have to be artificially limited. Git is about working together with people potentially on other systems, and "on this system you cannot have 'master' and 'Master' at the same time, because we have a patch to case-fold the refnames" would not be a good longer term solution.