Re: [PATCH v3 0/7] Gets rid of "if reflog exists, append to it regardless of config settings"

[Han-Wen Nienhuys <hanwen@google.com>]

On Thu, Oct 7, 2021 at 7:38 PM Junio C Hamano <gitster@pobox.com> wrote:
> > Not really.  I think the comment on the RFC still stands, and I do
> > not recall seeing a response to the point.
> >
> >     One potential harm this change will bring to us is what happens to
> >     people who disable core.logAllRefUpdates manually after using the
> >     repository for a while.  Their @{4} will point at the same commit no
> >     matter how many operations are done on the current branch after they
> >     do so.  I wouldn't mind if "git reflog disable" command is given to
> >     the users prominently and core.logAllRefUpdates becomes a mere
> >     implementation detail nobody has to care about---in such a world, we
> >     could set the configuration and drop the existing reflog records at
> >     the same time and nobody will be hurt.

A git 'reflog disable' command would address your concerns, but it is
a destructive operation, so the cure might be worse than the solution.

> IIRC, the only reason why reftable implementation may want to change
> the behaviour we have to avoid getting blamed for breaking is
> because it cannot implement "a reflog exists, and we need to record
> further ref movements by appending to it, no matter what the
> configuration says" when the existing reflog is empty, because its
> data structure lacks support for expressing "exists but empty".
>
> I think the behaviour change described in the title of this message
> can be limited in the scope to hurt users a lot less, and can still
> satisfy the goal of helping reftable not getting blamed for
> breakage, perhaps by making the behaviour for an empty but existing
> reflog unspecified or implementation defined per backend.

If we accept implementation-dependent features, we could just leave
the whole feature as is. I had expected more breakage, but there is
only one test case in t1400 that needs addressing. If the test
coverage reflects the popularity of the feature, it should be fine to
leave this divergence in, and mark the test with REFFILES.

The commits prior to the RFC should be OK for committing. In
particular, there is a bugfix for the show-branch command. Should I
resend those separately?

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Han-Wen Nienhuys - Google Munich
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