Date: Thu, 31 Jul 2003 17:49:55 -0400 From: Garance A Drosihn <drosih@rpi.edu> To: naddy@mips.inka.de (Christian Weisgerber), freebsd-current@freebsd.org Subject: Re: make -U Message-ID: <p052106acbb4f3e74d79a@[128.113.24.47]> In-Reply-To: <bgb67e$12kl$1@kemoauc.mips.inka.de> References: <20030730212049.GI33188@sunbay.com> <20030730162320.A66578@FreeBSD.org> <20030730212744.GJ33188@sunbay.com> <20030730163705.A68092@FreeBSD.org> <bgb67e$12kl$1@kemoauc.mips.inka.de>
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At 1:39 PM +0000 7/31/03, Christian Weisgerber wrote:
>Juli Mallett <jmallett@FreeBSD.org> wrote:
>
> > Why go thru those contortions? I sometimes use "make FOO=" to
> > define things. -U obviously has a place, if it not existing
> > means I have to have all these contortions to do a fairly
> > obvious thing, yeah?
>
>What are the exact semantics of -U supposed to be?
From the message in freebsd-hackers which first introduced
this patch:
- Date: Tue, 29 Jul 2003 09:09:17 -0700
- From: Faried Nawaz <fn@hungry.com>
- Subject: patch to add make -U
While working around a port issue (ports/55013), I discovered
that make couldn't unset variables using make -U. I've written
a small patch that adds -U functionality, but I haven't tested
it extensively.
http://web.nilpotent.org/tmp/make.diff.bz2 (~ 3KB unpacked)
against yesterday's -CURRENT code.
A simple Makefile I used to test it:
-- cut here --
FOO = bar
.ifdef FOO
SAY = y
.else
SAY = n
.endif
all:
echo $(SAY)
-- cut here --
Try "make -U FOO".
Personally I think this is a reasonable option to implement.
An undefined variable is not the same as a variable which is
defined to be a null string.
--
Garance Alistair Drosehn = gad@gilead.netel.rpi.edu
Senior Systems Programmer or gad@freebsd.org
Rensselaer Polytechnic Institute or drosih@rpi.edu
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