Re: [PATCH v2 0/1] Make 'git commit' not accidentally lose staged content

> On Mon, Sep 17, 2018 at 07:29:26PM +0200, Duy Nguyen wrote:
> > I don't see a good way to get to recover this situation. I could go
> > back to the "index log" idea, where we keep a log of index changes (or
> > just "interesting" changes). That way there's no behavior change at
> > all. The user who accidentally updates/deletes something can always
> > retrieve the old content back (assuming that they realize quickly
> > since we can't keep very long log).
>
> FWIW, I like that approach much better, since:
>
>   1. It does not bother or restrict anybody in their workflow; instead,
>      they pay the complexity price only when they know they have made a
>      mistake.
>
>   2. It covers many more cases (e.g., just doing the wrong thing via
>      "add -p").
>
> A naive index log would be pretty cheap in CPU, at least for POSIX-ish
> systems. You could just hard link "index" to "index.N" before renaming
> "index.lock" over "index". But I guess if you have a gigantic index,
> that's less appealing. So maybe storing the equivalent of a "--raw" diff
> between the two index states would make more sense (and after all, you
> don't really need the stat-cache or cache-tree). It would cost more to
> reconstruct the index on the fly, but then the point is that you would
> create these logs a lot more than you access them.

> > I've been thinking about allowing to undo worktree changes too (e.g.
> > accidental "git reset --hard") and this log can cover it as well.
>
> I like that, too. It's a little more costly just because it may involve
> object-db writes, but I think in most cases it would be fine. I almost
> always "git stash" away discarded changes these days instead of "git
> reset --hard", because it effectively provides this kind of log.

> > The only downside is we need a new command for the UI (or perhaps I
> > can just add "git add --log" or something like that).
>
> I think the reflog approach has been successful: give these intermediate
> states a name. So in theory I could do something like:
>
>   git checkout -p :@{2.minutes.ago}
>
> though it would probably be useful to be able to walk the states, too,
> just like we have "log --reflog-walk".
>
> The syntax above is off-the-cuff (and based on the ":<stage>" index
> syntax). I guess if we had a separate log for "stuff in the worktree
> that got thrown away by reset" we might need a separate syntax.