Re: What's cooking in git.git (Aug 2021, #02; Tue, 3)

> On Wed, Aug 04, 2021 at 09:53:02PM +0200, Ævar Arnfjörð Bjarmason wrote:
> > 
> > On Wed, Aug 04 2021, Junio C Hamano wrote:
> > 
> > > Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
> > >
> > >>> * ab/test-columns (2021-08-02) 3 commits
> > >>>  - test-lib.sh: use GIT_TEST_COLUMNS over COLUMNS
> > >>>  - test-lib-functions.sh: add a test_with_columns function
> > >>>  - test-lib-functions.sh: rename test_must_fail_acceptable()
> > >>
> > >> We're going to need this or another solution to the v2.33.0-rc0
> > >> regression in c49a177beca (test-lib.sh: set COLUMNS=80 for --verbose
> > >> repeatability, 2021-06-29) before the final v2.33.0.
> > >
> > > Just a question.  Is that true?  Wouldn't a system that needs these
> > > on top of c49a177beca already break the tests without c49a177beca?
> > >
> > > IOW, is c49a177beca truly a "regression", or is it merely "a half
> > > solution that solves for most but not all platforms"?
> > 
> > Yes, because with c49a177beca your tests only break if you use the
> > --verbose option, i.e. if your stderr is connected to a terminal. I.e.:
> > 
> >     ./t0500-progress-display.sh --verbose
> > 
> > So in practice it mostly affects git developers who run with --verbose,
> > but probably nobody doing a build in the wild.
> > 
> > With c49a177beca they break on e.g.:
> > 
> >     /bin/bash ./t0500-progress-display.sh
> > 
> > If your bash is recent enough, so "make test" if you're on a system with
> > a recent bash whose /bin/sh is /bin/bash.
> > 
> > This is because post-c49a177beca we don't "unset" COLUMNS anymore, which
> > bash takes as license to update it.
> > 
> > So we really do need that series in before the release to avoid that
> > common annoyance, a revert of c49a177beca is also possible, i.e. it
> > would still leave things broken under --verbose, but that breakage is
> > rare and existed before v2.33.
> > 
> > I think given the triviality of the fixes and that the cause is
> > well-understood it makes sense to go forward in this case.
> 
> On one hand, there is feedback to be addressed:
> 
>   https://public-inbox.org/git/20210802171429.GC23408@szeder.dev/
> 
> OTOH, setting the checkwinsize is the truly trivial, minimal, reliable

> and uncontroversial fix for this issue, and IMO that should go into
> the next release.
> 
> This fix in this patch series is not trivial: it introduces yet
> another GIT_TEST variable and a helper function that developers will
> have to remember to use in the future.  Worse, this means that despite
> aiming for future proofing I can't consider this approach future
> proof, because it's easy to forget about such a rarely used test
> helper function, and if anyone introduces yet another test setting
> COLUMNS, then that will be prone to similar failures when run with
> Bash.
> 
> I don't think that in this case we should aim for future proofing when
> the cost is the additional cognitive load of yet another helper
> function.  I would instead prefer to go with the really trivial fix
> for now and wait whether this issue pops up again with other shell or
> terminal, hoping that this issue is a "one-hit-wonder" [1] and it
> won't happen ever again.
> 
> 
> [1] "one-hit-wonder" as in:
>     https://en.wikipedia.org/wiki/Bloom_filter#Cache_filtering
>