Re: [PATCH v2 4/5] Makefile: add the ".DELETE_ON_ERROR" flag

From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Junio C Hamano <gitster@pobox.com>
Cc: "Jeff King" <peff@peff.net>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	git@vger.kernel.org, "Jonathan Nieder" <jrnieder@gmail.com>
Subject: Re: [PATCH v2 4/5] Makefile: add the ".DELETE_ON_ERROR" flag
Date: Thu, 1 Apr 2021 00:29:03 +0200 (CEST)	[thread overview]
Message-ID: <nycvar.QRO.7.76.6.2104010026440.54@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <xmqq35wb891a.fsf@gitster.g>

Hi,

On Wed, 31 Mar 2021, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
>
> > I don't know how paranoid we want to be about this, especially the
> > latter. My general inclination is to prefer "commit" systems as more
> > robust, but it is just a Makefile.
>
> ;-)
>
> As an old timer, I've written "gen >$@+ && mv $@+ $@" all the time
> myself, but it is ugly and felt a bit too conservative.  I do not
> think it is wise to overnight remove all the existing "generate in
> temporary, move to the final" patterns and delegate $(MAKE) to take
> care of failed generator with this mechanism, but I actually would
> feel it probably gives us a cleaner Makefile in the longer term.  At
> least "bugs in $(MAKE)" won't be our sole problem (i.e. all other
> projects that rely on the feature would share the incentives to see
> them fixed).

Another point in favor of removing that hack is this: `+` is not a valid
character in Windows' filenames. It just so _happens_ that Cygwin (and
therefore the MSYS2 Bash/`make` we use to compile Git for Windows)
_pretends_ that it is a valid filename character, but regular Win32
programs cannot read/write such files, and it would preclude Git from
being compiled with more native versions of a POSIX shell or `make`.

Ciao,
Dscho