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From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, Jeff King <peff@peff.net>,
	Johannes Schindelin <johannes.schindelin@gmx.de>,
	Jonathan Nieder <jrnieder@gmail.com>
Subject: Re: [PATCH v2 1/5] Makefile: rename objects in-place, don't clobber
Date: Wed, 31 Mar 2021 16:17:10 +0200	[thread overview]
Message-ID: <87pmzfl861.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <xmqqh7ktfq3y.fsf@gitster.g>


On Tue, Mar 30 2021, Junio C Hamano wrote:

> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>
>>> Really, does anybody else use "$(CC) -o $@" in such a way in their
>>> Makefile?  Having to do this smells simply crazy (I am not saying
>>> you are crazy---the platform that forces you to write such a thing
>>> is crazy).
>>
>> Yes, if you do say a Google search for "Cannot open or remove a file
>> containing a running program" you'll find that there's 15k results of
>> people basically (re)discovering this problem in porting their software
>> to AIX, and the solutions being some variant of "yes AIX sucks, just use
>> this 'cmd >x+ && mv x+ x' trick".
>
> What I meant was if there are well known upstream projects whose
> Makefile actually use
>
> 	$(CC) -o $@+ ...
> 	mv $@+ $@
>
> I wouldn't be surprised if AIX community maintained collections of
> patches to many projects to turn
>
> 	$(CC) -o $@ ...
>
> in the Makefiles taken from upstream projects into
>
> 	$(CC) -o $@+ ...
> 	mv $@+ $@
>
> to work AIX around.  As an upstream, however, I am not interested in
> forcing that pattern on users of other platforms.

Who's going to notice or care? We have some mixture of clobbering, "mv
$@+ $@" etc. now in our Makefile for various rules and I think unless
you're debugging those specific rules you won't notice.

The case of the $@+ being left behind is quite obscure, and with *+ in
our .gitignore won't be noticed (e.g. by a "git add ." or something).

> In any case, I do not care too much about the "I am building a new
> binary while running, without installing, the one I built" use case
> and do not agree with the idea of making the Makefile ugly only to
> support such a use case.  That is where my comments are coming from
> on this topic.  FWIW, AIX developers who do not do the "build, run
> without installing, and rebuild while the old one is still running"
> will not need the "$(CC) -o $@+ && mv $@+ $@" either, right?

I daresay that uses cases of:

 * The tests break, you login to the CI to run gdb, fix a small bug,
   compile (doesn't work), but being forced to close that gdb session
   would be annoying (e.g. maybe I'm just looking at a data in a struct
   I didn't change).

 * Ditto, but maybe debugging two things at the same time, having an
   open "cat-file --batch" session etc.

Aren't something obscure to someone wanting to work on a codebase. I'm
submitting these because this is an active impediment to me submitting
portability patches on AIX, of which I already have some:

    git log --grep=AIX --author=Ævar origin/master

Anything that makes that less painful is a win, and the tiny amount of
Makefile complexity seems worth it to me.

  reply	other threads:[~2021-03-31 14:17 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-07 13:20 [PATCH] Makefile: generate 'git' as 'cc [...] -o git+ && mv git+ git' Ævar Arnfjörð Bjarmason
2021-03-07 20:41 ` Junio C Hamano
2021-03-08 12:38   ` Ævar Arnfjörð Bjarmason
2021-03-08 17:21     ` Junio C Hamano
2021-03-08 18:26     ` Jeff King
2021-03-29 16:20 ` [PATCH v2 0/5] Makefile: don't die on AIX with open ./git Ævar Arnfjörð Bjarmason
2021-03-29 16:20   ` [PATCH v2 1/5] Makefile: rename objects in-place, don't clobber Ævar Arnfjörð Bjarmason
2021-03-29 18:21     ` Junio C Hamano
2021-03-29 18:26       ` Junio C Hamano
2021-03-29 23:24       ` Ævar Arnfjörð Bjarmason
2021-03-30  0:21         ` Junio C Hamano
2021-03-31 14:17           ` Ævar Arnfjörð Bjarmason [this message]
2021-03-31 18:50             ` Junio C Hamano
2021-03-29 16:20   ` [PATCH v2 2/5] Makefile: rename scripts " Ævar Arnfjörð Bjarmason
2021-03-29 18:40     ` Junio C Hamano
2021-03-29 23:28       ` Ævar Arnfjörð Bjarmason
2021-03-29 16:20   ` [PATCH v2 3/5] Makefile: don't needlessly "rm $@ $@+" before "mv $@+ $@" Ævar Arnfjörð Bjarmason
2021-03-29 18:46     ` Junio C Hamano
2021-03-29 16:20   ` [PATCH v2 4/5] Makefile: add the ".DELETE_ON_ERROR" flag Ævar Arnfjörð Bjarmason
2021-03-29 18:51     ` Junio C Hamano
2021-03-29 23:31       ` Ævar Arnfjörð Bjarmason
2021-03-29 23:58         ` Junio C Hamano
2021-03-30 15:11         ` Jeff King
2021-03-30 18:36           ` Junio C Hamano
2021-03-31  6:58             ` Jeff King
2021-03-31 18:36               ` Junio C Hamano
2021-03-31 22:29                 ` Johannes Schindelin
2021-03-29 16:20   ` [PATCH v2 5/5] Makefile: don't "rm configure" before generating it Ævar Arnfjörð Bjarmason
2021-03-29 16:31   ` [PATCH 0/6] Makefile: make non-symlink & non-hardlink install sane Ævar Arnfjörð Bjarmason
2021-03-29 16:31     ` [PATCH 1/6] Makefile: symlink the same way under "symlinks" and "no hardlinks" Ævar Arnfjörð Bjarmason
2021-03-29 22:17       ` Junio C Hamano
2021-03-29 16:31     ` [PATCH 2/6] Makefile: begin refactoring out "ln || ln -s || cp" pattern Ævar Arnfjörð Bjarmason
2021-03-29 22:20       ` Junio C Hamano
2021-03-29 16:31     ` [PATCH 3/6] Makefile: refactor " Ævar Arnfjörð Bjarmason
2021-03-29 22:24       ` Junio C Hamano
2021-03-30 15:20         ` Jeff King
2021-03-30 18:36           ` Junio C Hamano
2021-03-29 16:31     ` [PATCH 4/6] Makefile: make INSTALL_SYMLINKS affect the build directory Ævar Arnfjörð Bjarmason
2021-03-29 22:31       ` Junio C Hamano
2021-03-31 14:04         ` Ævar Arnfjörð Bjarmason
2021-03-29 16:31     ` [PATCH 5/6] Makefile: use "ln -f" instead of "rm && ln" Ævar Arnfjörð Bjarmason
2021-03-29 22:46       ` Junio C Hamano
2021-03-29 16:31     ` [PATCH 6/6] Makefile: add a INSTALL_FALLBACK_LN_CP mode Ævar Arnfjörð Bjarmason
2021-03-29 22:53       ` Junio C Hamano
2021-03-31 14:03         ` Ævar Arnfjörð Bjarmason
2021-03-31 18:45           ` Junio C Hamano
2021-03-31 19:01             ` Ævar Arnfjörð Bjarmason
2021-03-29 23:08     ` [PATCH 0/6] Makefile: make non-symlink & non-hardlink install sane Junio C Hamano

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