Re: [PATCH 0/7] [RFC] advice: refuse to output if stderr not TTY

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 21, 2024, 16:36 UTC
Message-ID: <xmqqbk1l25p3.fsf@gitster.g>
In-Reply-To: <pull.1776.git.1724238152.gitgitgadget@gmail.com>

"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:

> Advice is supposed to be for humans, not machines. Why do we output it when
> stderr is not a terminal? Let's stop doing that.

Last night while skimming the series on my phone (read: not a real review at all), I found it very annoying that GIT_ADVICE=1 had to be sprinkled all over the place. I wonder if we want to instead set and export it in t/test-lib.sh and turn it off as needed?

The end-to-end tests we have are primarily to guarantee the continuity of the end-user experience by humans, and ensuring that an advice message is given when appropriate and it does not get shown otherwise is very much inherent part of them. An alternative workaround to counteract the breakage this series causes of course is to run everything under test_terminal and it probably is much more kosher philosophically ;-), but compared to that, globally disabling the "if (!isatty(2))" while running the tests, and temporarily lifting that disabling during tests of the new feature added by this series would be easier to reason about, I would suspect.

Show 5 quoted lines

> This series is motivated by an internal tool breaking due to the advice
> message added to Git 2.46.0 by 9479a31d603 (advice: warn when sparse index
> expands, 2024-07-08). This tool is assuming that any output to stderr is an
> error, and in this case is attempting to parse it to determine what kind of
> error (warning, error, or failure).

The "anything on stderr is an error" attitude needs to be fixed regardless of where it comes from (tcl/tk scripts have, or at least used to have, the tendency, which I found annoying), but regardless, I thought we added a mechanism to squelch all advice messages for this exact purpose at f0e21837 (Merge branch 'jl/git-no-advice', 2024-05-16). Why isn't the tool using the mechanism that already exists?

I would have supported the behaviour proposed by this series 100% if it were on the table when we were introducing the advise mechanism, but unfortunately nobody seemed have suggested it back then. I am willing to go with an "experiment" to change the behaviour, deliberately breaking "backward compatibility", if we have a wide support here during the review period. FWIW, I think any scripts that scrape the advice messages are already broken.