Hi all, here's a quick howto for building OpenWRT on OS X 10.9 (Mavericks) using MacPorts. I'm not sure when, but Apple dropped GCC support completely (I jumped from Lion to Mavericks without going to ML). Now, gcc is just a stub for the clang compiler -- which sucks for anyone who must use gcc to compile their programs. Fortunately, we can install the old llvm-gcc42 compiler and gcc47 from MacPorts to get a clean build.
NOTE: This howto is for 12.09 attitude_adjustment. I have no idea if this will work for trunk.
Here's what I've found so far:
Apple's clang-500.2.79 doesn't build anything.
llvm-gcc42 builds the tools, but not the toolchain.
gcc47 builds the toolchain and firmware, but has problems building tools/e2fsprogs (see https://dev.openwrt.org/ticket/12441 for details).
gcc48 has the same issue with e2fsprogs and fails to build the toolchain.
I'm assuming everyone knows how to set up the OpenWRT build environment for OS X. There are several howtos in the forum and the wiki. This is simply help for getting things set up in Mavericks.
First, Xcode does not install the command line tools by default and it's no longer an option in the preferences. It needs to be set up from the command line now. This document has everything you need to get MacPorts running properly in Mavericks: http://trac.macports.org/wiki/MavericksProblems.
At this point you should have installed MacPorts and all the build prerequisites (including llvm-gcc42 and gcc47), and prepared the .config file using 'make menuconfig'. Now, here's what I did to get a successful build:
$ sudo port select --set gcc mp-llvm-gcc42
Selecting 'mp-llvm-gcc42' for 'gcc' succeeded. 'mp-llvm-gcc42' is now active.
$ hash -r
$ gcc --version
i686-apple-darwin13-llvm-gcc-4.2 (GCC) 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11) (MacPorts llvm-gcc42 2336.11_1)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ export PATH=/opt/local/libexec/gnubin:/opt/local/bin:${PATH}
$ make dirclean && make tools/install
make[1] clean
make[2] target/linux/clean
make[3] -C target/linux clean
make[1] dirclean
make[2] target/linux/clean
make[3] -C target/linux clean
Collecting package info: done
Collecting target info: done
Checking 'working-make'... ok.
Checking 'case-sensitive-fs'... ok.
Checking 'getopt'... ok.
Checking 'fileutils'... ok.
Checking 'working-gcc'... ok.
Checking 'working-g++'... ok.
Checking 'ncurses'... ok.
Checking 'zlib'... ok.
Checking 'gawk'... ok.
Checking 'unzip'... ok.
Checking 'bzip2'... ok.
Checking 'patch'... ok.
Checking 'perl'... ok.
Checking 'python'... ok.
Checking 'wget'... ok.
Checking 'git'... ok.
Checking 'gnutar'... ok.
Checking 'svn'... ok.
Checking 'gnu-find'... ok.
Checking 'getopt-extended'... ok.
Checking 'non-root'... ok.
make[1] tools/install
make[2] -C tools/m4 compile
make[2] -C tools/m4 install
make[2] -C tools/sed compile
make[2] -C tools/sed install
make[2] -C tools/libtool compile
make[2] -C tools/libtool install
make[2] -C tools/autoconf compile
make[2] -C tools/autoconf install
make[2] -C tools/pkg-config compile
make[2] -C tools/pkg-config install
make[2] -C tools/xz compile
make[2] -C tools/xz install
make[2] -C tools/automake compile
make[2] -C tools/automake install
make[2] -C tools/gmp compile
make[2] -C tools/gmp install
make[2] -C tools/mpfr compile
make[2] -C tools/mpfr install
make[2] -C tools/mpc compile
make[2] -C tools/mpc install
make[2] -C tools/libelf compile
make[2] -C tools/libelf install
make[2] -C tools/flex compile
make[2] -C tools/flex install
make[2] -C tools/bison compile
make[2] -C tools/bison install
make[2] -C tools/mklibs compile
make[2] -C tools/mklibs install
make[2] -C tools/sstrip compile
make[2] -C tools/sstrip install
make[2] -C tools/ipkg-utils compile
make[2] -C tools/ipkg-utils install
make[2] -C tools/genext2fs compile
make[2] -C tools/genext2fs install
make[2] -C tools/e2fsprogs compile
make[2] -C tools/e2fsprogs install
make[2] -C tools/mtd-utils compile
make[2] -C tools/mtd-utils install
make[2] -C tools/mkimage compile
make[2] -C tools/mkimage install
make[2] -C tools/firmware-utils compile
make[2] -C tools/firmware-utils install
make[2] -C tools/patch-cmdline compile
make[2] -C tools/patch-cmdline install
make[2] -C tools/quilt compile
make[2] -C tools/quilt install
make[2] -C tools/yaffs2 compile
make[2] -C tools/yaffs2 install
make[2] -C tools/flock compile
make[2] -C tools/flock install
make[2] -C tools/padjffs2 compile
make[2] -C tools/padjffs2 install
make[2] -C tools/mm-macros compile
make[2] -C tools/mm-macros install
make[2] -C tools/xorg-macros compile
make[2] -C tools/xorg-macros install
make[2] -C tools/xfce-macros compile
make[2] -C tools/xfce-macros install
make[2] -C tools/missing-macros compile
make[2] -C tools/missing-macros install
make[2] -C tools/cmake compile
make[2] -C tools/cmake install
make[2] -C tools/scons compile
make[2] -C tools/scons install
make[2] -C tools/lzma compile
make[2] -C tools/lzma install
make[2] -C tools/squashfs4 compile
make[2] -C tools/squashfs4 install
make[2] -C tools/b43-tools compile
make[2] -C tools/b43-tools install
$ sudo port select --set gcc mp-gcc47
Selecting 'mp-gcc47' for 'gcc' succeeded. 'mp-gcc47' is now active.
$ hash -r
$ gcc --version
gcc (MacPorts gcc47 4.7.3_3) 4.7.3
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ make
make[1] world
make[2] toolchain/install
make[3] -C toolchain/gdb prepare
make[3] -C toolchain/gdb compile
make[3] -C toolchain/gdb install
make[3] -C toolchain/binutils prepare
make[3] -C toolchain/binutils compile
make[3] -C toolchain/binutils install
make[3] -C toolchain/gcc/minimal prepare
make[3] -C toolchain/gcc/minimal compile
make[3] -C toolchain/gcc/minimal install
make[3] -C toolchain/kernel-headers prepare
make[3] -C toolchain/kernel-headers compile
make[3] -C toolchain/kernel-headers install
make[3] -C toolchain/uClibc/headers prepare
make[3] -C toolchain/uClibc/headers compile
make[3] -C toolchain/uClibc/headers install
make[3] -C toolchain/gcc/initial prepare
make[3] -C toolchain/gcc/initial compile
make[3] -C toolchain/gcc/initial install
make[3] -C toolchain/uClibc prepare
make[3] -C toolchain/uClibc compile
make[3] -C toolchain/uClibc install
make[3] -C toolchain/gcc/final prepare
make[3] -C toolchain/gcc/final compile
make[3] -C toolchain/gcc/final install
make[3] -C toolchain/uClibc/utils prepare
make[3] -C toolchain/uClibc/utils compile
make[3] -C toolchain/uClibc/utils install
make[2] target/compile
make[3] -C target/linux compile
make[2] package/cleanup
make[2] package/compile
make[3] -C package/toolchain compile
make[3] -C package/apex compile
make[3] -C package/libnl-tiny compile
make[3] -C package/libjson-c compile
make[3] -C package/lua compile
make[3] -C package/libubox compile
make[3] -C package/ubus compile
make[3] -C package/uci compile
make[3] -C package/netifd compile
make[3] -C package/opkg host-compile
make[3] -C package/base-files compile
make[3] -C package/ncurses compile
make[3] -C package/util-linux compile
make[3] -C package/block-mount compile
make[3] -C package/busybox compile
make[3] -C package/dnsmasq compile
make[3] -C package/dropbear compile
make[3] -C package/e2fsprogs compile
make[3] -C package/fconfig compile
make[3] -C feeds/luci/freifunk-common compile
make[3] -C feeds/luci/community-profiles compile
make[3] -C feeds/routing/olsrd compile
make[3] -C package/iptables compile
make[3] -C package/firewall compile
make[3] -C package/iproute2 compile
make[3] -C feeds/luci/freifunk-gwcheck compile
make[3] -C feeds/luci/freifunk-mapupdate compile
make[3] -C package/iwinfo compile
make[3] -C package/lua host-compile
make[3] -C package/px5g compile
make[3] -C package/uhttpd compile
make[3] -C feeds/luci/luci compile
make[3] -C package/hostapd compile
make[3] -C package/hotplug2 compile
make[3] -C package/iw compile
make[3] -C package/ixp4xx-microcode compile
make[3] -C package/kernel compile
make[3] -C package/mac80211 compile
make[3] -C package/mtd compile
make[3] -C package/opkg compile
make[3] -C package/libpcap compile
make[3] -C package/linux-atm compile
make[3] -C package/resolveip compile
make[3] -C package/ppp compile
make[2] package/install
make[3] -C package/apex install
make[3] -C package/block-mount install
make[3] -C package/busybox install
make[3] -C package/dnsmasq install
make[3] -C package/dropbear install
make[3] -C package/e2fsprogs install
make[3] -C package/fconfig install
make[3] -C feeds/luci/luci install
make[3] -C package/firewall install
make[3] -C package/hostapd install
make[3] -C package/hotplug2 install
make[3] -C package/iptables install
make[3] -C package/iw install
make[3] -C package/iwinfo install
make[3] -C package/ixp4xx-microcode install
make[3] -C package/kernel install
make[3] -C package/libjson-c install
make[3] -C package/libnl-tiny install
make[3] -C package/libubox install
make[3] -C package/lua install
make[3] -C package/mac80211 install
make[3] -C package/mtd install
make[3] -C package/netifd install
make[3] -C package/opkg install
make[3] -C package/ppp install
make[3] -C package/toolchain install
make[3] -C package/ubus install
make[3] -C package/uci install
make[3] -C package/uhttpd install
make[3] -C package/util-linux install
make[3] -C package/base-files install
make[2] package/rootfs-prepare
make[3] package/preconfig
make[2] target/install
make[3] -C target/linux install
make[2] package/index Now, I need to flash the firmware and see if this thing actually works. 
Good luck!