Subject: Re: [PATCH v7 2/8] cherry-pick: treat CHERRY_PICK_HEAD and REVERT_HEAD as refs

From: David Turner <[email-masked]>
Date: Wed, 08 Jul 2015 15:16:02 -0400

On Wed, 2015-07-08 at 19:46 +0200, Johannes Sixt wrote:
> Am 08.07.2015 um 02:55 schrieb David Turner:
> > Instead of directly writing to and reading from files in
> > $GIT_DIR, use ref API to interact with CHERRY_PICK_HEAD
> > and REVERT_HEAD.
> >
> > Signed-off-by: David Turner <[email-masked]>
> > ---
> ...
> > diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
> > index 366f0bc..e2c5583 100644
> > --- a/contrib/completion/git-prompt.sh
> > +++ b/contrib/completion/git-prompt.sh
> > @@ -415,9 +415,9 @@ __git_ps1 ()
> >   			fi
> >   		elif [ -f "$g/MERGE_HEAD" ]; then
> >   			r="|MERGING"
> > -		elif [ -f "$g/CHERRY_PICK_HEAD" ]; then
> > +		elif git rev-parse --quiet --verify "CHERRY_PICK_HEAD" >/dev/null; then
> >   			r="|CHERRY-PICKING"
> > -		elif [ -f "$g/REVERT_HEAD" ]; then
> > +		elif git rev-parse --quiet --verify "REVERT_HEAD" >/dev/null; then
> >   			r="|REVERTING"
> >   		elif [ -f "$g/BISECT_LOG" ]; then
> >   			r="|BISECTING"
> 
> We are trying very hard not to spawn any new processes in __git_ps1(). 
> So, I raise a moderate veto against this hunk.

Do you have an alternate suggestion about how to accomplish the same
thing? Here are my ideas:

We could special-case CHERRY_PICK_HEAD and REVERT_HEAD to be files
independent of the ref backend, but that tends to complicate the
backends.  I think this is a mistake.

We could reduce the number from two to one by providing a new
git-am-status command which outputs one of "CHERRY-PICKING",
"REVERTING", or "" (or maybe it would also handle rebase and am).  We
could also generalize it to "git-prompt-helper" or something by moving
that entire bunch of if statements inside.  This would replace calls to
"git describe".

But you probably have a better idea.