Date: Fri, 20 Aug 2004 10:44:58 +0200 From: Oliver Eikemeier <eikemeier@fillmore-labs.com> To: current@freebsd.org Subject: setting CFLAGS in /etc/make.conf Message-ID: <377474F4-F285-11D8-A951-00039312D914@fillmore-labs.com>
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I have a problem with the following recommendation in
src/share/examples/etc/make.conf:
# CFLAGS controls the compiler settings used when compiling C code.
# Note that optimization settings other than -O and -O2 are not
recommended
# or supported for compiling the world or the kernel - please revert any
# nonstandard optimization settings to "-O" before submitting bug reports
# without patches to the developers.
# Note also that at this time the -O2 setting is known to expose bugs in
# libalias(3), and possibly other parts of the system.
#
#CFLAGS= -O -pipe
Basically, when a port tries to pass CFLAGS to the distribution
Makefile, this is done by
env CFLAGS="${CFLAGS}" make
which is effectively overwritten by users setting CFLAGS in
make.conf(5). OTOH when += is used, it inherits the previous values, so
when someone would do
CFLAGS+= -O -pipe
in make.conf(5) the effective value passed is "-O -pipe -O -pipe
${_CPUCFLAGS}", which is not harmful, but not good either. This is
especially problematic when the port uses CFLAGS="${PTHREAD_CFLAGS}" or
CFLAGS="-DMY_OPTION", and a lot of ports use CFLAGS. This is no problem
when the port has USE_GMAKE, since gmake doesn't read make.conf(5).
The following Makefile illustrates the problem:
all:
@env CFLAGS="${CFLAGS} -DFOO" ${MAKE} cflags
.ifmake cflags
CFLAGS+= -DBAR
.endif
cflags:
@${ECHO} "CFLAGS=${CFLAGS}"
with the output:
CFLAGS=-O -pipe ${_CPUCFLAGS} -DFOO ${_CPUCFLAGS} -DBAR
Basically this is the expected result, although the ${_CPUCFLAGS} is
unfortunately doubled. This is what a typical port would see. When I now
set
CFLAGS= -O -pipe
in make.conf(5), which is the example given in
share/examples/etc/make.conf, I get:
CFLAGS=-O -pipe ${_CPUCFLAGS} -DBAR
so I loose the settings done in the ports Makefile (-DFOO).
One solution would be to set __MAKE_CONF=/dev/null in bsd.port.mk,
another solution is to deprecate setting CFLAGS in make.conf(5), or use
an alternate variable.
Generally I believe it is unexpected that an reexecution of make(1)
overwrites CFLAGS explicitly passed in the environment, so deprecating
its usage is my favorite option here. Btw, passing CFLAGS in the command
line is not an option, since Makefiles need to be able to add to the
value.
Thoughs?
-Oliver
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