bug#68183: 28.3; vc-dir fails when I have a certain branch checked out

[Kévin Le Gouguec]

Dmitry Gutov <dmitry@gutov.dev> writes:

>> Re. optimizing the display (which I interpret as reducing redundant
>> information): as someone who often works with multiple remotes, seeing
>> "Branch: FOO ; Tracking: origin/FOO" is actually useful, so I wouldn't
>> want to remove the "tracking" bit unconditionally.  OTOH it could surely
>> be condensed to a single line, say
>>      Branch     : master (tracking: origin/master)
>
> Yeah, something like this could work. I was imagining pseudo-graphical
>
>      Branch     : master -> origin/master
>
> , but it's good to have words. Maybe drop the last colon...

Right, feels like we have some horizontal space to work with, so we can
spend the extra word if it conveys more meaning than an arrow (and yeah,
OTOH that last colon does not bring much).

>> Likewise, in the local-tracking-branch case, we could go from
>>      Branch:    : vc-dir-bug
>>      Tracking   : master
>>      Remote     : none (tracking local branch)
>> to just
>>      Branch:    : vc-dir-bug (tracking: local master)
>
> I would say that the local-tracking scenario is a minority, and so it's not 
> as important to optimize, but the above makes sense. But the word "local" is 
> very close to "master", while the latter is a special string which should 
> probably somehow stand out. So the "unoptimized" version might still have its 
> advantages:
>
>       Branch:    : vc-dir-bug (tracking master)
>       Remote     : none (local branch)

That looks sensible.  If I were to argue in favor of keeping "local"
juxtaposed to the tracking branch, I'd say that in the _absence_ of an
explicit qualifier in "Branch: vc-dir-bug (tracking master)", my brain
might "default" to assuming we are tracking the remote "master"; a
solution to let branch names stand out might then be faces:
e.g. vc-git-log-view-mode paints them with change-log-list…

But I don't know if it's a very powerful argument.

>>> Just a thought. Not something that needs to be addressed right now. And I 
>>> might as well be off the mark here.
>> I agree it's worth thinking about.  The Right Solution™ would probably
>> come with user options to let users fine-tune which details they care
>> about?  It would be interesting to survey Git UIs to see how they
>> approach this (FWIW I am partial to Magit's presentation, but I have not
>> studied how it handles all the corner cases we considered).
>
> Magit, meaning just one line for Head: and another for Merge:?

So, given

𝒷   ≔ current branch
𝓂   ≔ branch.𝒷.merge
𝓇   ≔ branch.𝒷.remote
𝓅   ≔ branch.𝒷.pushRemote or remote.pushDefault

By default, magit-status shows:

"Head:"                 𝒷, or the current commit when detached
"Merge:" (or "Rebase:") 𝓇/𝓂, or just 𝓂 if 𝓇 = "."
"Push:"                 𝓅/𝒷, appending "does not exist" if applicable

(And another header related to tags I'm going to ignore for now)

Of note, Magit offers an option (magit-status-headers-hook) to let users
control which of these (and more) to display.

One of the available headers that is disabled by default shows

"Remote: ℛ <remote.ℛ.url>"

where ℛ is 𝓇, or "origin" if this branch's remote is unset or ".", or
"the first remote in alphabetic order" if "origin" does not exist.

(
  Also of note, IMO, is the branch-variable-configuration menu (the
  magit-branch-configure transient), which looks like this:

      Configure vc-dir-bug
       d branch.vc-dir-bug.description unset
       u branch.vc-dir-bug.merge refs/heads/master
         branch.vc-dir-bug.remote .
       r branch.vc-dir-bug.rebase [true|false|default:false]
       p branch.vc-dir-bug.pushRemote 
[hirondell|origin|savannah-rw|vps|remote.pushDefault:vps]

      Configure repository defaults
       R pull.rebase [true|false|default:false]
       P remote.pushDefault [hirondell|origin|savannah-rw|vps]
       b Update default branch

      Configure branch creation
       a m branch.autoSetupMerge [always|true|false|default:true]
       a r branch.autoSetupRebase [always|local|remote|never|default:never]
      __
  (Not pictured: the currently active value in [foo|bar|baz] is
  highlighted with a face; the keybindings on the left cycle between
  alternatives)

  No idea how/where that would fit into VC, but golly is it a neat UI to
  work with, so I thought it deserved a shout-out.
)

>>>>> * maybe the new header deserves a NEWS entry.
>>>> Maybe?
>>>
>>> It wouldn't hurt. Up to you.
>>>
>>> Anyway, I think the patch is good to go. Please feel free to install it; 
>>> whatever cosmetic changes we might like to add could be done later.
>> ACK.  I might go a head and install then (after polishing the changelog,
>> i.e. re-filling and scrubbing Unicode ellipses) in the spirit of getting
>> the original issue fixed; perhaps worth holding off on the NEWS entry
>> until we decide how exactly things should look.
>
> I'm okay with that.

(Pushed 📨)