using clang (was: Re: ps, clang and make variables)

[Conrad J. Sabatier]

On Sat, 31 Mar 2012 11:11:25 -0400
Robert Huff <roberthuff at rcn.com> wrote:

> 
> 	As long as we're talking about clang, I have two questions.
> 	1) Is there any generic reason why a port compiled with clang
> won't work on a world compiled with gcc?

No, none that I'm aware of.  I've occasionally seen mention of
this-or-that port causing problems if built with clang, not always
directly, but sometimes affecting other ports that depend on it.

> 	2) If not, how do I set that up?

The "standard" method is to include the following in
your /etc/make.conf (also see the comments after this):

#
# use clang unless gcc is explicitly required
#

.if !defined(USE_GCC)
.if !defined(CC) || ${CC} == "cc"
CC=clang
.endif
.if !defined(CXX) || ${CXX} == "c++"
CXX=clang++
.endif
.if !defined(CPP) || ${CPP} == "cpp"
CPP=clang-cpp
.endif
.endif

Over a span of several months, I've gradually amassed a list of ports
I use myself which either won't build successfully with clang, or have
some sort of runtime issues when built with clang (these have a
tendency to change over time with new releases of a given port).  For
these, I've added some "exception" lines to force them to be built
either with the base system gcc (4.2) or the lang/gcc port (4.6). 

Note that these exceptions have to *precede* the previous lines in
order for them to override the above clang settings.

You can also override the clang settings at the command line by doing
"make USE_GCC=4.2 (or 4.2+)" or "make USE_GCC=4.6 (or 4.6+)", for
example.  If you do do this from the command line, just be sure to be
consistent with it, i.e., you don't want to do a "make USE_GCC=4.6
configure" followed by a plain "make" or "make install".  Pretty much
sure to lead to trouble.  :-)

Note, too, that none of these exceptions have anything to do with my
/usr/src builds.  I've been using clang for buildworld and buildkernel
for quite some time now.

###############################################################
# (need to put this up here before the following clang stuff)
#
# ports which either won't build using clang, or that have
# runtime issues when built with clang
#
##############################################################

#
# default to using clang for all port builds, with the following
# exceptions

# ports which will only build with the base system GNU compiler (4.2)
#
# the "make index" target also seems to need this, for some reason

.if target(index) | \
${.CURDIR:M*/devel/antlr*} | \
${.CURDIR:M*/devel/google-perftools* } | \
${.CURDIR:M*/graphics/ImageMagick* } | \
${.CURDIR:M*/graphics/opencv*} | \
${.CURDIR:M*/www/libxul*} | \
${.CURDIR:M*/x11/kdelibs4*} | \
${.CURDIR:M*/x11-toolkits/swt-devel*}
USE_GCC?=4.2
.endif

# ports which need *some* version of the GNU compiler (won't build with
# clang or have runtime issues if built with clang)
# use the highest version of gcc we have installed from ports (4.6)

.if ${.CURDIR:M*/accessibility/jovie*} | \
${.CURDIR:M*/accessibility/kdeaccessibility4*} | \
${.CURDIR:M*/audio/grip*} | \
${.CURDIR:M*/audio/mpg123*} | \
${.CURDIR:M*/audio/rosegarden*} | \
${.CURDIR:M*/databases/virtuoso*} | \
${.CURDIR:M*/deskutils/kdepimlibs4*} | \
${.CURDIR:M*/devel/apache-ant*} | \
${.CURDIR:M*/devel/binutils*} | \
${.CURDIR:M*/devel/icu*} | \
${.CURDIR:M*/devel/kdevelop-kde4*} | \
${.CURDIR:M*/devel/kdevplatform*} | \
${.CURDIR:M*/devel/log4j*} | \
${.CURDIR:M*/games/kdegames4*} | \
${.CURDIR:M*/graphics/tonicpoint-viewer*} | \
${.CURDIR:M*/java/* } | \
${.CURDIR:M*/lang/gcc*} | \
${.CURDIR:M*/math/fftw3*} | \
${.CURDIR:M*/multimedia/avidemux2*} | \
${.CURDIR:M*/multimedia/kdemultimedia4*} | \
${.CURDIR:M*/multimedia/vlc*} | \
${.CURDIR:M*/multimedia/xbmc*} | \
${.CURDIR:M*/net/kdenetwork4*} | \
${.CURDIR:M*/net/mpich2*} | \
${.CURDIR:M*/net/opal3*} | \
${.CURDIR:M*/net-p2p/ktorrent*} | \
${.CURDIR:M*/net-p2p/vuze*} | \
${.CURDIR:M*/sysutils/lsof*} | \
${.CURDIR:M*/textproc/docbook-xsl*} | \
${.CURDIR:M*/textproc/fop*} | \
${.CURDIR:M*/www/firefox*} | \
${.CURDIR:M*/x11/kde4-baseapps*} | \
${.CURDIR:M*/x11/kde4-workspace*} | \
${.CURDIR:M*/x11/lxpanel*} | \
${.CURDIR:M*/x11-toolkits/swt*}
USE_GCC?=4.6+
.endif

Hope this helps somewhat.  :-)

-- 
Conrad J. Sabatier
conrads at cox.net