Re: [PATCH] Proof-of-concept patch to remember what the detached HEAD was

[James Pickens <jepicken@gmail.com>]

On Wed, Oct 14, 2009 at 4:09 PM, Jeff King <peff@peff.net> wrote:
> That makes the most sense to me. If "git checkout" could write metadata
> into HEAD (or into DETACH_HEAD, as in Daniel's patch), then checkout
> could record an "ok to commit" bit. And could also be used to change it
> after the fact. E.g.:
>
>  $ git checkout --detach=commit origin/master
>  $ git commit ;# should be ok
>
>  $ git checkout --detach=examine origin/master
>  $ git commit ;# complain
>  $ git checkout --detach=commit HEAD
>  $ git commit ;# ok
>
> I guess something like "rebase" should detach with "ok to commit", since
> it is planning on attaching the commits later. I'm not sure about "git
> bisect". I guess probably it should be "not ok to commit" to be on the
> safe side, and then somebody can "git checkout --detach=commit" if they
> want to.

How about not detaching the head at all if the user checks out any ref, and
reject commits if he checked out a tag or remote branch.  For example:

$ git checkout origin/master
$ git status
# On branch origin/master
$ git commit ;# complain

$ git checkout v1.0.1
$ git status
# On tag v1.0.1
$ git commit ;# complain

$ git checkout v1.0.1^0 ;# detach
$ git commit ;# ok

I think this would help the newbies and wouldn't cost the experts too much.
Checking out anything other than a plain ref would still detach the head, and
commits on a detached head would still be allowed.  Perhaps as an additional
safety feature, Git could refuse to switch away from a detached head if the head
isn't reachable from any ref, and require -f to override:

$ git checkout $sha1
$ git commit
$ git checkout master ;# complain
$ git checkout -f master ;# ok

Maybe I'm missing something and this all can't be done, but it seems simpler
than the other options I've seen in this thread.

James