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Date: Mon, 28 Jan 2008 11:35:00 +0000
From: Thiemo Seufer <ths@networkno.de>
Subject: Re: [Qemu-devel] [PATCH] CPPFLAGS+= in Makefile.target
Message-ID: <20080128113500.GA23119@networkno.de>
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	<200801251439.58215.paul@codesourcery.com>
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To: Ronan Keryell <Ronan.Keryell@enstb.org>
Cc: qemu-devel@nongnu.org

Ronan Keryell wrote:
> >>>>> On Fri, 25 Jan 2008 14:39:57 +0000, Paul Brook <paul@codesourcery.com> said:
> 
>     >> Saying CPPFLAGS+= is much more convenient if for any reason the
>     >> external build environment would like to pass unusual CPPFLAGS.
> 
>     Paul> No. This doesn't do what you thing it does.  The most common way
>     Paul> of overriding these variables is to pass them on the
>     Paul> commandline, i.e. "make CPPFLAGS=-blah". This overrides all
>     Paul> assignments to that variable including +=.
> 
> By the way, it is possible to improve the GNU make weirdness :-) by
> playing with stuff like:
> 
> override CFLAGS += -g
> 
> Cf section 6.7 of the documentation.

IIRC the documentation warns against careless use of overrides.

> Hmmm... GNU make evolves more rapidly than my brain... :-)

It's only a decade old or so. :-)


Thiemo