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:
>
> > > On the other hand, if I am keeping some change that should never be
> > > in a commit in the working tree file, and building the contents in
> > > the index using "add -p" to incrementally, it would be the same
> > > disaster as you are trying to prevent if I by mistake did a whole
> > > path 'add', even if I catch myself doing so before running 'commit'
> > > i.e.
> > >
> > >         edit X
> > >         git add -p X
> > >         git diff --cached X
> > >         git diff X
> > >         ... repeat the above number of times ...
> > >         git add X ;# OOPS!
> > >         git add . ;# OOPS! even worse!
> > >
> > > Even though this does not involve "git commit -a" or "git commit X",
> > > an unrecoverable damage that requires redoing the manual work is
> > > already done.
> >
> > 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.
>