Building libpurple3 on OSX with homebrew

I've spent a far amount of time this week working on making it easier (or even possible in some cases) to build libpurple3 on OSX.  I haven't gotten to Gtk+ yet, so I haven't even tried compiling Pidgin yet.

Typically OSX isn't one of first party supported platforms, but I'm on vacation this week and only have a MacBook at my immediate disposal.  So here we are ;)

Most of the issues have been in the generation of the configure script and landed in PR #103.  But there was a side effect from an earlier PR that became a problem on OSX since homebrew does not have farstream.  PR #107 has been submitted to fix that.

When PR #107 is merged everything should be buildable.  But it does not and will not work out of the box.  Why you ask? Politics!  (of course...)

Homebrew attempts to play things very safe, which is admirable, but a giant pain when you're actually trying to compile something that isn't already in Homebrew.  So we go about making this easier by using a little known feature of Pidgin's build system.

Years ago I got tired of trying to remember what arguments I was passing to autogen.sh and configure.  So like any programmer, I added code that would do it for me!  That code sources a shell script named autogen.args from the directory you invoke autogen.sh from.  So in the root of my build directory I have a file named autogen.args with the following content:

export PKG_CONFIG_PATH=$(brew --prefix libffi)/lib/pkgconfig:$(brew --prefix libxml2)/lib/pkgconfig

CONFIGURE_FLAGS="--disable-gtkui --disable-consoleui --disable-vv --disable-kwallet --disable-meanwhile --disable-avahi --disable-dbus --disable-gnome-keyring --enable-introspection"

As you can see, I'm disabling a ton of stuff to make this build work, but that's not all.  Notice the PKG_CONFIG_PATH environment variable being exported.  This is dealing with Homebrew's policy of staying out of the system's way.  OSX has it's own version of libffi and libxml2 so Homebrew will not install any part of those packages where the system will look for them.  This has the unfortunate side effect of causing weird build failures until you realize this is the problem.

At any rate, I hope this has been helpful to someone :)