Date: Sun, 19 Dec 2010 14:10:48 +0200 From: Peter Pentchev <roam@ringlet.net> To: Alexander Best <arundel@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: question about CFLAGS, CXXFLAGS and DEBUG_FLAGS Message-ID: <20101219121048.GA3835@straylight.ringlet.net> In-Reply-To: <20101218212431.GA35554@freebsd.org> References: <20101218200937.GA2932@freebsd.org> <20101218204047.GA4214@straylight.ringlet.net> <20101218212431.GA35554@freebsd.org>
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On Sat, Dec 18, 2010 at 09:24:31PM +0000, Alexander Best wrote:
> On Sat Dec 18 10, Peter Pentchev wrote:
> > On Sat, Dec 18, 2010 at 08:09:37PM +0000, Alexander Best wrote:
> > > hi there,
> > >=20
> > > i just stumbled over these lines:
> > >=20
> > > otaku% grep -n \${DEBUG_FLAGS} /usr/share/mk/bsd.prog.mk
> > > 24:CFLAGS+=3D${DEBUG_FLAGS}
> > > 25:CXXFLAGS+=3D${DEBUG_FLAGS}
> > >=20
> > > is it really necessary to assign the debug flags to both CFLAGS *and*=
CXXFLAGS?
> >=20
> > Uhm... yes, so they can be used in both C and C++ programs :)
> > ...or are you making the mistake I've made too many times (and still
> > make sometimes) of confusing CXXFLAGS with CPPFLAGS? :)
>=20
> *hehehe* i don't think so.
Nah, just making sure, no offense intended :)
> i just saw a lot of these lines in buildworld:
>=20
> clang++ -O2 -pipe -DNDEBUG -g -I/usr/obj/usr/subversion-src/tmp/legacy/us=
r/include -I/usr/subversion-src/gnu/usr.bin/gperf/../../../contrib/gperf/li=
b -I/usr/subversion-src/gnu/usr.bin/gperf -g -c /usr/subversion-src/gnu/usr=
=2Ebin/gperf/../../../contrib/gperf/lib/hash.cc
> clang++: warning: argument unused during compilation: '-g'
> clang++: warning: argument unused during compilation: '-g'
>=20
> as you can see -g gets specified twice, so i thought maybe adding -g to
> CFLAGS makes adding it to CXXFLAGS obsolete.
Well, according to my copy of src/share/mk/sys.mk (8.x-STABLE),
if the user does not override CXXFLAGS, they are copied from CFLAGS
with some exceptions. Thus, it does seem sensible to add -g to
both sets of flags - yes, if no CXXFLAGS are specified, the -g will
be doubled, but if CXXFLAGS *are* specified in the environment or on
the make(1) command line, then only one -g will be added.
Maybe a better solution could be to somehow test for empty CXXFLAGS
in sys.mk and set another variable that says "we've copied those over",
and then only add DEBUG_FLAGS to CXXFLAGS if that variable is not set,
but I'm not sure if it's really worth it.
Thanks for bringing this up - I wasn't aware of the fact that CXXFLAGS
were copied over unless overridden :) Learn something new every day,
I guess.
G'luck,
Peter
--=20
Peter Pentchev roam@space.bg roam@ringlet.net roam@FreeBSD.org
PGP key: http://people.FreeBSD.org/~roam/roam.key.asc
Key fingerprint FDBA FD79 C26F 3C51 C95E DF9E ED18 B68D 1619 4553
No language can express every thought unambiguously, least of all this one.
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