Re: [PATCH v2] wt-status: use rename settings from init_diff_ui_defaults

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

Elijah Newren <newren@gmail.com> writes:

> I'm not certain what the default should be, but I do believe that it
> should be consistent between these commands.  I lean towards
> considering break detection being on by default a good thing, but
> there are some interesting issues to address:
>   - there is no knob to adjust break detection for status, only for
> diff/log/show/etc.
>   - folks have a knob to turn break detection on (for diff/log/show),
> but not one to turn it off
>   - for status, break detection makes no sense if rename detection is off.
>   - for diff/log/show, break detection provides almost no value if
> rename detection is off (only a dissimilarity index), suggesting that
> if user turns rename detection off and doesn't explicitly ask for
> break detection, then it's a waste of time to have it be on
>   - merge-recursive would break horribly right now if someone turned
> break detection on for it.  Turning it on might be a good long term
> goal, but it's not an easy change.

Many of the issues in the above list are surmountable.  A new option
could be added to "status" to enable break or "diff" family to
disable it if we really wanted to.  A new "rewritten" state can be
added alongside with "modified" to "status" output.

A more serious issue around "-B" is this one:

    https://public-inbox.org/git/xmqqegqaahnh.fsf@gitster.dls.corp.google.com/

Even though the message is back from 2015 and asks users not to use
-B/-M together for anything critical "for now", the issue has not
been resolved and the same bug remains with us in the current code.

In the longer term, I suspect that it might make sense to have an
option to let users choose among "I do not want to have anything to
do with -B", "I always want -B when I ask for -M" and "I always want
-B whether I ask for -M".  But unfortunately the latter two with the
current codebase is an unacceptably risky/broken choice.

>
> So, where does that leave us?  My opinion is
>   - these commands should be consistent.  Eckhard's patch makes them so.
>   - we might want to move towards break detection being on as the
> default.  That's a couple patch series (one for everything but
> merge-recursive, and a separate much bigger series for
> merge-recursive).
>
> But I can see others saying we should leave things inconsistent until
> we can fix the other commands to use break detection as the default.
> So...thoughts?
>
> Elijah