On Wed, Aug 04 2021, Junio C Hamano wrote: > Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> writes: > [...] >> By narrowly targeting a fix at one specific shell's cleverness around >> COLUMNS we'll leave open a window where we'll fail on other shells if >> they introduce similar cleverness. >> >> It hardly seems like a stretch that once bash starts doing that sort of >> thing other shells might think to follow suit, and all have their own >> non-standard way to turn it off. > > Hmph. Wouldn't the same argument apply to the much simpler single > liner "shopt -u" solution? When writing new tests, there is nothing > to remember, and a new shell that needs a different trick to defeat > the auto-COLUMNS would be detected quickly by running the tests in a > terminal whose width is different from 80, no? It's different in the "bisecting" case I mentioned. I.e. "shopt -u" is a shell-specific solution, the approach I'm suggesting bypasses any sort of shell-specific solutions, both current and future ones. >> You also didn't address the other rationale for it, namely that it's >> also future-proofing us for submarine breakages in non-git programs >> which'll understand the new COLUMNS=10, but not GIT_TEST_COLUMNS=80. > > Isn't that another downside of the approach you are advocating? > > If we make Git rely on GIT_TEST_COLUMNS, we may honor it while > everybody else ignores it. If we only have to deal with COLUMNS > like everybody else does, Git and other tools that are used in our > tests will be affected the same way by overly-clever shells, no? I think it's an upside. We know how git handles the combination of GIT_TEST_COLUMNS, COLUMNS and TIOCGWINSZ. We have no idea how any third-party program decides to behave. So by intentionally spoiling COLUMNS=* and only having our tests pay attention to GIT_TEST_COLUMNS we pretty much guarantee that we won't grow some dependency on a non-git program's handling of COLUMNS, which e.g. could differ from platform to platform. I don't know about any such case, and spoiling COLUMNS didn't reveal any. I just thought it was worthwhile to once-and-for-all get us away from any sort of shell or 3rd party code cleverness around COLUMNS, as opposed to a very narrow bugfix for just the issue we've spotted with bash recently.
