Re: [PATCH v4 00/16] Fix git-gc losing objects in multi worktree

[Duy Nguyen <pclouds@gmail.com>]

On Fri, Aug 25, 2017 at 6:21 PM, Michael J Gruber <git@grubix.eu> wrote:
> I suggest we think about the UI exposure a bit when it
> comes to including all heads or naming options, though:
>
> * HEAD is "the current head"
> * refs/heads is where all local branch heads are
>
> * --branches is the rev-list/log option for refs/heads/*
> * --all is the rev-list/log option for refs/* plus HEAD
> * HEAD is the rev-list/log argument for HEAD

It also covers object references from the index file aka --indexed-objects

> * --heads is the show-ref option limiting to refs/heads/*
> * --head is the show-ref option which adds HEAD
>
> * refs/heads is the for-each-ref-pattern for refs/heads/*
> * HEAD is not the for-each-ref-pattern for HEAD
> [I'll suggest a patch to change the latter, shortly.]
>
> I would hope that the result of this series and other efforts will be:
>
> * consistent way to specify "all local branch heads"
> * consistent way to specify "the head" aka HEAD
> * consistent way to specify "all linked worktree heads"
> [* maybe something for submodules...]

Hmm.. I admit that I completely overlooked 'git show-ref'.

> This may require changing the misnamed show-ref option, but also
> thinking twice before changing the meaning of "--all" for the
> rev-list/log family: it's easy to say "--all --linked" or "--all
> --heads" to get everything plus all linked worktree heads when "--all"
> == "--branches --tags HEAD", but it's more cumbersome with a changed
> --all that is "really everything". I gues my suggestion would be:
>
> --all as it is now (refs/* plus HEAD)
>
> --head alternative way to say HEAD (as it is now for show-ref)
>
> --heads HEAD for all linked worktrees (incompatible change for show-ref)
>
> And all of them should work the same for the rev-list/log family as well
> as for-each-ref/show-ref.

How about: show-ref learns a new option to let it list HEAD (and other
per-worktree refs) of one/current worktree, or all worktrees. This is
what the --single-worktree option is for, which is added by this
series (but I need to make sure if's exposed in show-ref as well). For
showing refs as viewed by another worktree, we could have the global
option similar to --git-dir to select that worktree, e.g. "git
--work-tree-id=XXX show-ref ..."?

Since this seems a good thing to do, but not necessary to fix the
"prune" bug, I'll do it separately instead of adding in this series. I
may need to look at "git for-each-ref" too for that matter.

> I thinking that changing show-ref (porcelain, not quite as commonly
> used) should do the least harm compared to all other options.
-- 
Duy