From: "Ævar Arnfjörð Bjarmason" <email@example.com> To: Junio C Hamano <firstname.lastname@example.org> Cc: Jeff King <email@example.com>, firstname.lastname@example.org Subject: Re: [PATCH 1/4] Makefile: don't re-define PERL_DEFINES Date: Thu, 06 May 2021 11:04:34 +0200 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> On Thu, May 06 2021, Junio C Hamano wrote: > Ævar Arnfjörð Bjarmason <email@example.com> writes: > >>>> -PERL_DEFINES = $(PERL_PATH_SQ):$(PERLLIB_EXTRA_SQ):$(perllibdir_SQ) >>>> - >>>> -PERL_DEFINES := $(PERL_PATH_SQ) $(PERLLIB_EXTRA_SQ) $(perllibdir_SQ) >>>> +PERL_DEFINES := >>>> +PERL_DEFINES += $(PERL_PATH_SQ) >>>> +PERL_DEFINES += $(PERLLIB_EXTRA_SQ) >>>> +PERL_DEFINES += $(perllibdir_SQ) >>>> PERL_DEFINES += $(RUNTIME_PREFIX) >>> >>> I don't think we generally use simply-expanded variables in our Makefile >>> unless there's a reason. Do we actually need it here? Obviously not new >>> in your patch, but just a curiosity I noticed while reading it. >> >> I didn't notice it at the time. I suppose it could be changed to not do >> expansion, but per-se unrelated to the more narrorw bugfix in this >> patch. > > Actually, strictly speaking there was *no* bug because assigning > three items with := made sure the previous recursively expanded one > to be ineffective. In other words, there was a valid reason to use > ":=" there in the original version. Yes, there wasn't any bug with the the eventual value being incorrect. I.e. both of these are equivalent in a Makefile: FOO = abc FOO := def FOO += ghi And: FOO = abc FOO = def FOO += ghi Both will yield "def ghi". They're just different in a case like: X = Y FOO = abc FOO := $(X) X = Z FOO += ghi Where using := will echo "Y ghi", and using = will echo "Z ghi". As a practical matter the distinction doesn't matter in this case. > Now your patch removed the recursively expanded one that was > immediately invalidated, there no longer is a reason to use := > there. So "unrelated to the more narrow bugfix" is a rather lame > excuse to do only half a task. If we remove that extra one (which > is a good thing), then we should correct := into = because the > original used := only because there was the unwanted extra one, no? I don't see how removing the stray line changes the reason to use ":=" or "=" there. I agree it should be removed, it's just unrelated to removing the stay line. Looking at 07d90eadb50 it's clear that it's just some copy/pasting error. Maybe the confusion is that I'm using "bug" closer to a meaning of "a thing nobody intended to be in the program", not just "a behavior-changing issue observable from the outside". In any case. I can just submit a patch on top of this in a v2. I continue to find it hard to discover the line between superfluous while-we're-at-it fixes in your mind v.s. "we should fix this while we're at it" though :) But regarding the "half a task" it seems to me that these are different issues; I don't think that's a point worth arguing in this case specifically (let's just fix it, and I will), but perhaps I'm missing something subtle with regards to Makefile semantics per my examples above so it really is all one issue, and I'd like to understand how they're entwined.
next prev parent reply other threads:[~2021-05-06 9:19 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-05 12:21 [PATCH 0/4] Makefile/perl: correctly re-generate build/* + speed up under NO_GETTEXT=Y Ævar Arnfjörð Bjarmason 2021-05-05 12:21 ` [PATCH 1/4] Makefile: don't re-define PERL_DEFINES Ævar Arnfjörð Bjarmason 2021-05-05 14:08 ` Jeff King 2021-05-06 1:05 ` Junio C Hamano 2021-05-06 16:55 ` Jeff King 2021-05-06 6:23 ` Ævar Arnfjörð Bjarmason 2021-05-06 8:42 ` Junio C Hamano 2021-05-06 9:04 ` Ævar Arnfjörð Bjarmason [this message] 2021-05-06 16:59 ` Jeff King 2021-05-07 8:42 ` Junio C Hamano 2021-05-05 12:21 ` [PATCH 2/4] Makefile: regenerate perl/build/* if GIT-PERL-DEFINES changes Ævar Arnfjörð Bjarmason 2021-05-05 12:21 ` [PATCH 3/4] Makefile: regenerate *.pm on NO_PERL_CPAN_FALLBACKS change Ævar Arnfjörð Bjarmason 2021-05-05 12:21 ` [PATCH 4/4] perl: use mock i18n functions under NO_GETTEXT=Y Ævar Arnfjörð Bjarmason 2021-05-10 10:50 ` [PATCH v2 0/6] Makefile/perl: correctly re-generate build/* + speed up " Ævar Arnfjörð Bjarmason 2021-05-10 10:50 ` [PATCH v2 1/6] Makefile: regenerate perl/build/* if GIT-PERL-DEFINES changes Ævar Arnfjörð Bjarmason 2021-05-10 10:50 ` [PATCH v2 2/6] Makefile: don't re-define PERL_DEFINES Ævar Arnfjörð Bjarmason 2021-05-10 10:50 ` [PATCH v2 3/6] Makefile: make PERL_DEFINES recursively expanded Ævar Arnfjörð Bjarmason 2021-05-10 10:50 ` [PATCH v2 4/6] Makefile: split up the deceleration of PERL_DEFINES Ævar Arnfjörð Bjarmason 2021-05-10 10:50 ` [PATCH v2 5/6] Makefile: regenerate *.pm on NO_PERL_CPAN_FALLBACKS change Ævar Arnfjörð Bjarmason 2021-05-10 10:50 ` [PATCH v2 6/6] perl: use mock i18n functions under NO_GETTEXT=Y Ævar Arnfjörð Bjarmason 2021-05-10 18:17 ` [PATCH v2 0/6] Makefile/perl: correctly re-generate build/* + speed up " Junio C Hamano 2021-05-11 6:56 ` Ævar Arnfjörð Bjarmason 2021-05-11 7:05 ` Junio C Hamano 2021-05-12 9:49 ` [PATCH] Makefile: make PERL_DEFINES recursively expanded Ævar Arnfjörð Bjarmason 2021-05-12 19:53 ` Jeff King 2021-05-12 22:45 ` Junio C Hamano
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