Re: [PATCH] Makefile: add and use the ".DELETE_ON_ERROR" flag

From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Taylor Blau" <me@ttaylorr.com>,
	git@vger.kernel.org,
	"Felipe Contreras" <felipe.contreras@gmail.com>
Subject: Re: [PATCH] Makefile: add and use the ".DELETE_ON_ERROR" flag
Date: Mon, 28 Jun 2021 23:19:21 -0700	[thread overview]
Message-ID: <xmqqfsx1yyza.fsf@gitster.g> (raw)
In-Reply-To: YNqE8BIRF6NeYQcd@coredump.intra.peff.net

Jeff King <peff@peff.net> writes:

> Yeah, I can see the view that running the test suite as a basic sanity
> check may have value, if it's backed by more careful testing later (and
> certainly while I'm developing, I wouldn't hesitate to run a subset of
> the test suite to see how my work is progressing).
>
> My main point was that I don't see much reason to do work to make that
> kind of continuous "make test" work with simultaneous recompiles and
> test-runs, if we can encourage people to do it more robustly with a
> single compile-and-test-run loop. Maybe adding in the extra workdir
> there makes it too heavy-weight? (Certainly my "ci" script is overkill,
> but it seems like a loop of "reset to the current branch tip, compile,
> run" in a worktree would be the minimal thing).

I actually do use such a "runs tests in the background while I am
not watching", so I am sympathetic to the higher-level goal, but I
find any execution of the idea that requires "let's reduce the
window where freshly built 'git' or any other things are not ready
by forcing 'mv $@+ $@' trick for added atomicity" simply insane and
not worth supporting.

Tests are run to find cases where things go wrong, and it is a waste
of cycles if that background task is not being run in isolation and
on a stable state.  A separate working tree is so easy to set up
these days, I do not see a point in complicating the build procedure
to avoid using it.