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

From: Jeff King <peff@peff.net>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: Junio C Hamano <gitster@pobox.com>,
	git@vger.kernel.org,
	Johannes Schindelin <johannes.schindelin@gmx.de>,
	Jonathan Nieder <jrnieder@gmail.com>
Subject: Re: [PATCH v2 4/5] Makefile: add the ".DELETE_ON_ERROR" flag
Date: Tue, 30 Mar 2021 11:11:07 -0400	[thread overview]
Message-ID: <YGM/i+k4r0q8FKg2@coredump.intra.peff.net> (raw)
In-Reply-To: <87a6qlmt9f.fsf@evledraar.gmail.com>

On Tue, Mar 30, 2021 at 01:31:40AM +0200, Ævar Arnfjörð Bjarmason wrote:

> >> Use the GNU make ".DELETE_ON_ERROR" flag.
> >
> > Yay!
> >
> > With versions of $(MAKE) where this feature is available, it is far
> > more preferrable to use it than "generate into temporary and rename
> > to the final" dance.
> >
> > We do require / depend on GNU but I do not offhand know if this is
> > available in all versions that still matter.  If we know we can
> > assume the presence of this feature the I do not mind if we jump
> > directly to this step without those "do the same for $(CC)" steps
> > (which I deem crazy) before it.
> 
> Even if it's not available in all versions that's OK. You just won't get
> the nicer removal behavior on on error on such a jurassic gmake, but
> you'll probably have way bigger issues with your late-90s-era software.
> 
> It's not a syntax error on a gmake or other make that doesn't know about
> it either, i.e. you can also add a target like:
> 
>     .THIS_DOES_NOT_EXIST_AS_A_GMAKE_FEATURE:
> 
> And gmake willl happily ignore it.

Yes, I think it's fine to treat it as "nice if we have it, but OK
otherwise". But also, .DELETE_ON_ERROR first shows up in the GNU make
git repository in version 3.71.5 from 1994. So I think we can probably
just assume it's everywhere.

-Peff