Re: [PATCH] checkout: honor advice.detachedHead when reattaching to a branch

On Fri, May 06, 2011 at 03:59:20PM -0700, Junio C Hamano wrote:

quoted

I'm somewhat negative on this. I think there are actually 5 distinct
pieces of information that git currently gives in going to and from a
detached HEAD, and the motivations for suppressing them may be
different:

  1. On detaching, we indicate briefly that the HEAD has been detached
     by saying "HEAD is now at ..." instead of "Switched to branch ...".

  2. On detaching, we give a large warning on what the detached HEAD
     state means, and advise on how to get out of it.

  3. On leaving, if there are no orphaned commits, we indicate briefly
     where the previous HEAD position was with "Previous HEAD position
     was...".

  4. On leaving, if there are orphaned commits, we list them.

  5. On leaving, if there are orphaned commits, we give advice on how to
     make branches out of them.

Right now, advice.detachedhead suppresses (2); that is, we leave the
short indicator that provides distinct per-use information to the user
(1), but suppress the lengthy advice that is not helpful to advanced
user.

So if you wanted symmetry, I think that would mean suppressing (5), but
leaving (4), which contains per-use information, intact.

The patch does leave per-use information by giving 3. "HEAD was" as you
noted above, and that is more than sufficient (you can also look at
HEAD@{0}).  If and only if the list is needed (i.e. the user wants to
recover), the user can run "git log $that_commit".

I think we're probably in agreement on how to go forward, but I wanted
to note one final thing. It is actually not the list itself which is
that valuable to me. It's merely a convenience; if I know there is
something worth looking at, I am perfectly capable of inspecting the
history graph myself.

The real value in the orphan-check to me is whether it says "hey, there
are orphaned commits" or not. Before we had that check, leaving the
detached state _always_ said "Previous HEAD was...", and I quickly
learned to ignore it as uninteresting noise in 99% of the cases. Whereas
in the orphan warning case, I find that I want to do something about it
in at least 50% of the cases. Thus I actually heed the warning, and it
is effective.

It's possible that some people would find it useful to print only the
"warning: you are leaving orphaned commits" message, but not show the
list of them. I don't think it is worth it, though. Leaving orphaned
commits is the uncommon case, and doing so without wanting to
investigate is probably even less common. So the user is not too likely
to get annoyed by a little extra verbosity in the uncommon false
positive case.

-Peff