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From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: "René Scharfe" <l.s.r@web.de>
Cc: Junio C Hamano <gitster@pobox.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org
Subject: Re: [PATCH] tests: replace mingw_test_cmp with a helper in C
Date: Thu, 08 Sep 2022 17:26:41 +0200	[thread overview]
Message-ID: <220908.861qsllw5x.gmgdl@evledraar.gmail.com> (raw)
In-Reply-To: <2d839209-21e2-b05c-125b-57a9c1dad1ea@web.de>


On Thu, Sep 08 2022, René Scharfe wrote:

> Am 07.09.22 um 18:25 schrieb Junio C Hamano:
>> René Scharfe <l.s.r@web.de> writes:
>>
>>>>> But otherwise the idea is sound.  We compare them line by line,
>>>>> using strbuf_getline() to ignore differences in CRLF and LF that
>>>>> originates at 4d715ac0 (Windows: a test_cmp that is agnostic to
>>>>> random LF <> CRLF conversions, 2013-10-26).  Only when we find the
>>>>> input different, we use "git diff --no-index" to make the difference
>>>>> (and unfortunately more, as it does not ignore CRLF <> LF
>>>>> differences) visible.
>>>
>>> Why not use "git diff --no-index --ignore-cr-at-eol"?  Do you even need
>>> to wrap it?
>>
>> Hmph.  That surely sounds sensible if it works, and I offhand do not
>> see why it shouldn't work.
>
> Using git diff in test_cmp and using test_cmp to check if git diff works
> would become a cyclical dependency.  Only doing that on one platform
> limits the potential blind spot to platform-specific bugs, though.
> Enough to go wrapper-less?  Not sure.

I don't see how being wrapper-less is less of a "cyclical dependency"
than using "git diff" directly.

If we are to postulate some bug where "git diff" thwarts us for the use
of "test_cmp" it's going to be *very* broken.

I don't see how such a "git diff" would pass the rest of the test suite
(some of which involves comparing its exact output), but still be
functional enough to work as a GIT_TEST_CMP.

Even one where it just returns 0 unconditionally wouldn't pass, as we
rely on "! test_cmp" in some cases.

And any such breakage we imagine might just as well affect a wrapper for
it, and I'd think that would be the more likely of two unlikely
possibilities, as that wrapper would only be used for the test suite,
whereas "git diff" is more widely tested.

In any case, as long as we preserve the ability to set a
GIT_TEST_CMP=cmp we can sanity check any such wrapper or dogfodding of
"git diff" with an external program.

Needing to deal just with "git diff" and "cmp" would be a step forward,
as we'd be able to drop the current shellscript "mingw" wrapper, as well
as the special support for a "diff" that doesn't understand "-u".

  reply	other threads:[~2022-09-08 15:32 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-29 14:53 [PATCH] tests: replace mingw_test_cmp with a helper in C Johannes Schindelin via GitGitGadget
2022-07-29 14:54 ` Johannes Schindelin
2022-07-29 16:44 ` Junio C Hamano
2022-09-06 13:10   ` Johannes Schindelin
2022-09-07 12:09     ` René Scharfe
2022-09-07 16:25       ` Junio C Hamano
2022-09-07 21:45         ` Re* " Junio C Hamano
2022-09-07 22:39           ` René Scharfe
2022-09-08  0:03             ` Junio C Hamano
2022-09-08  8:59         ` René Scharfe
2022-09-08 15:26           ` Ævar Arnfjörð Bjarmason [this message]
2022-09-08 20:54         ` Johannes Schindelin
2022-09-08 21:09           ` Junio C Hamano
2022-09-06 13:10 ` [PATCH v2 0/2] " Johannes Schindelin via GitGitGadget
2022-09-06 13:10   ` [PATCH v2 1/2] t0021: use Windows-friendly `pwd` Johannes Schindelin via GitGitGadget
2022-09-06 13:10   ` [PATCH v2 2/2] tests: replace mingw_test_cmp with a helper in C Johannes Schindelin via GitGitGadget
2022-09-07 11:57     ` Ævar Arnfjörð Bjarmason
2022-09-07 12:24       ` Ævar Arnfjörð Bjarmason
2022-09-07 19:45         ` Junio C Hamano
2022-09-07  9:04   ` [PATCH v2 0/2] " Johannes Schindelin
2022-11-12 22:07   ` [PATCH v3 " Johannes Schindelin via GitGitGadget
2022-11-12 22:07     ` [PATCH v3 1/2] t0021: use Windows-friendly `pwd` Johannes Schindelin via GitGitGadget
2022-11-12 22:07     ` [PATCH v3 2/2] tests(mingw): avoid very slow `mingw_test_cmp` Johannes Schindelin via GitGitGadget
2022-11-13  4:51       ` Taylor Blau
2022-11-14 13:34         ` Johannes Schindelin
2022-11-18 23:15         ` Junio C Hamano
2022-11-19  2:53           ` Taylor Blau
2022-11-19 12:03             ` Ævar Arnfjörð Bjarmason
2022-11-19  8:18           ` Johannes Sixt
2022-11-19 17:50             ` René Scharfe
2022-11-20  9:29               ` Torsten Bögershausen
2022-11-21 17:49               ` Johannes Sixt
2022-11-21  3:13             ` Junio C Hamano
2022-11-14  9:53       ` Phillip Wood
2022-11-14 13:47         ` Johannes Schindelin
2022-11-14 11:55       ` Ævar Arnfjörð Bjarmason
2022-11-14 14:02         ` Johannes Schindelin
2022-11-14 15:23           ` Ævar Arnfjörð Bjarmason
2022-11-18 23:19             ` Junio C Hamano
2022-11-19  2:56               ` Taylor Blau
2022-11-19 11:54                 ` Ævar Arnfjörð Bjarmason
2022-11-21  3:17                   ` Junio C Hamano
2022-11-14 14:06     ` [PATCH v4 0/2] tests(mingw): avoid super-slow mingw_test_cmp Johannes Schindelin via GitGitGadget
2022-11-14 14:06       ` [PATCH v4 1/2] t0021: use Windows-friendly `pwd` Johannes Schindelin via GitGitGadget
2022-11-14 14:06       ` [PATCH v4 2/2] tests(mingw): avoid very slow `mingw_test_cmp` Johannes Schindelin via GitGitGadget
2022-11-14 22:40         ` Taylor Blau
2022-11-18 13:32           ` Johannes Schindelin
2022-11-18 18:14             ` Taylor Blau
2022-11-20 23:36               ` Johannes Schindelin
2022-11-21  0:07                 ` Taylor Blau
2022-12-06 15:07       ` [PATCH v5 0/2] tests(mingw): avoid super-slow mingw_test_cmp Johannes Schindelin via GitGitGadget
2022-12-06 15:07         ` [PATCH v5 1/2] t0021: use Windows-friendly `pwd` Johannes Schindelin via GitGitGadget
2022-12-06 15:07         ` [PATCH v5 2/2] tests(mingw): avoid very slow `mingw_test_cmp` Johannes Schindelin via GitGitGadget
2022-12-06 18:55           ` Ævar Arnfjörð Bjarmason
2022-12-06 21:52           ` Johannes Sixt
2022-12-06 21:54           ` René Scharfe
2022-12-07  4:33             ` Junio C Hamano
2022-12-07  1:31           ` Taylor Blau

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