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Date: Tue, 7 Sep 2004 20:28:57 +0200
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To: John Polstra <jdp@polstra.com>
From: Oliver Eikemeier <eikemeier@fillmore-labs.com>
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cc: ports@freebsd.org
Subject: Re: Best way to override user's CFLAGS in a port?
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John Polstra wrote:

> The ezm3 port has to be built with an optimization level of -O, and
> that's not likely to change any time soon.  Some users, especially
> users of -current where -O2 is officially supported, are getting
> burned by that.  What is the best way for me to change the ezm3 port's
> Makefile so that -O will be used regardless of the user's environment
> or /etc/make.conf settings?

The Porters Handbook 
<http://www.freebsd.org/doc/en_US.ISO8859-1/books/porters-
handbook/dads-cflags.html> tells you to respect CFLAGS, which means you 
should add

.if defined(CFLAGS) && !empty(CFLAGS:M-O[2-9]*)
BROKEN=		"Doesn't build with ${CFLAGS:M-O[2-9]*}"
.endif

to your port, so that a user could use a workaround in make.conf(5) when 
necessary. Specifying CFLAGS in make.conf(5) is problematic for ports 
anyways, see <http://lists.freebsd.org/pipermail/freebsd-
current/2004-August/034763.html> (an example for a problematic port is 
net/obnc, which misses -DIPSEC).

If you just want a dirty hack, you could use

CFLAGS:=		${CFLAGS:N-O*} -O

but this won't work with recent make(1)s when CFLAGS is specified on the 
command line, and might lead to other problems. I guess the first 
solution is preferred.

-Oliver