Re: [PATCH v2 0/5] branch: fix branch operations with multiple working trees

[Junio C Hamano <gitster@pobox.com>]

Kazuki Yamaguchi <k@rhe.jp> writes:

> [1/5]
> Adds RESOLVE_REF_COMMON_DIR to resolve_ref_unsafe(). The second - fourth
> patch depend on this. At the same time, this allows us to remove
> reimplementation of resolve_ref_unsafe() in worktree.c: parse_ref().
>
> [2/5]
> Adds REF_COMMON_DIR flag to lock_ref_sha1_basic().

While the code reduction in 1/5 is a very good and welcome change,
these new flags make me wonder if they can be easily misused in a
way that contradicts with what other parts of the system (e.g.
path.c::common_list[]) tell us.  Am I worried too much without a
good reason?

> [3/5]
> Adds create_symref_common_dir(). Same as create_symref() except it
> doesn't consider $GIT_DIR. create_symref_common_dir("HEAD", some) always
> updates .git/HEAD. The next patch uses this.

Similarly, would this allow updating "refs/remotes/origin/HEAD"
(which is also a symbolic ref) to different values for different
worktrees?  In other words, I am wondering if this new function
should be narrower in scope--e.g. used only to update "HEAD" and
no other symbolic refs.  Or will the additional flexibility be
useful?

> [4/5]
> Fixes the issue of git branch -m.
> The behavior when one failed has changed from v1: print an error and
> continue.
>
>   % git branch -m oldname newname
>   error: Unable to create '/path/to/.git/worktrees/wt/HEAD.lock': Permission denied
>   error: HEAD of working tree /path/to/wt is not updated.
>   error: Unable to create '/path/to/.git/worktrees/wt2/HEAD.lock': Permission denied
>   error: HEAD of working tree /path/to/wt2 is not updated.
>   fatal: Branch renamed to newname, but HEAD is not updated!

Sounds like a good goal.