Re: [RFC/PATCH]: reverse bisect v 2.0

[Junio C Hamano <gitster@pobox.com>]

Andrew Ardill <andrew.ardill@gmail.com> writes:

> Examples.
> Search for a feature add:
>    $ git bisect start --introduced='feature: git frotz says xyzzy' v0.99 master
>    Bisecting: 171 revisions left to test after this (roughly 8 steps)
>    $ ... build and then test ...
>    $ git bisect tested
>    Does this snapshot have 'feature: git frotz says xyzzy' [y/n]? yes
> # already added, look backwards
>
> Search for a feature regression:
>    $ git bisect start --removed='feature: git frotz says xyzzy' v0.99 master
>    Bisecting: 171 revisions left to test after this (roughly 8 steps)
>    $ ... build and then test ...
>    $ git bisect tested
>    Does this snapshot have 'feature: git frotz says xyzzy' [y/n]? yes
> # not removed yet, look forwards

With an obvious addition of non-interactive short-cut subcommands "git
bisect yes" and "git bisect no", I think --removed= is a much better
wording than --used-to= I suggested in the discussion.

I however am still worried about the flipping of the mapping between
<good,bad> and <yes,no> this design requires. What are we going to do to
the labels of low-level machinery (i.e $GIT_DIR/refs/bisect/bad and
$GIT/refs/bisect/good)? They appear in "bisect visualize" and I was hoping
that it would be simpler in the code if we do not have to change them in
such a way that depends on this introduced/removed switch, and that was
the reason why I was trying to see if we can solve this without the
switchable mapping between <good,bad> and <yes,no>.

More specifically, I was hoping that we can rename "good" to "old" and
"bad" to "new" unconditionally and be done with it. We would ask the user
"What did the code used to do in the olden days?" and "Does this version
behave the same as it used to?". The possible answers the user can give
are "git bisect old" (it behaves the same as the older versions) and "git
bisect new" (it behaves the same as the newer versions). Then we do not
have to worry about having to flip the meaning of <yes> and <no> at the UI
level.