How to specify which GCC for MacPorts to use?

Question

I compiled GCC 4.4.3 and installed it in /usr/local/bin, but whenever I install a port via MacPorts 1.8.2 the verbose output says MacPorts is using /usr/bin/gcc-4.2:

checking for gcc... /usr/bin/gcc-4.2

How do I make MacPorts find my own GCC 4.4.3? Here is my existing path:

/opt/local/bin:/opt/local/sbin:/usr/local/bin:/usr/local/lib:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin

I am running Mac OS X 10.6.2 Snow Leopard.

Answer 1

First answer: Don't! In my experience, GCC 4.4.3 will not work properly on Snow Leopard. It will cause problems with zero-length strings.

Second answer: edit your symbolic links in /usr/bin to refer to the 4.4 stuff. Here's a script I wrote to do so:

rm /usr/bin/c++ 
ln -s /usr/bin/c++-${1} /usr/bin/c++
rm /usr/bin/cc
ln -s /usr/bin/cc-${1} /usr/bin/cc
rm /usr/bin/cpp
ln -s /usr/bin/cpp-${1} /usr/bin/cpp
rm /usr/bin/g++
ln -s /usr/bin/g++-${1} /usr/bin/g++
rm /usr/bin/gcc
ln -s /usr/bin/gcc-${1} /usr/bin/gcc
rm /usr/bin/gcov
ln -s /usr/bin/gcov-${1} /usr/bin/gcov

I called it chgCver, so to change my compiler to 4.4, I'd type chgCver 4.4. Of course, before you run this, you'll also need to make sure that, for example, c++-4.4 points to the correct place (probably /opt/local/bin/gcc-mp-4.4), etc. I can give you more specifics, if you're inclined to ignore my first and third answers.

Third answer: Don't! (See first answer.)

Answer 2

MacPorts is using Apple supplied compilers wherever possible as they are highly patched for the platform. For example, they allow to build for multiple architectures by specifying -arch flags which is not possible with FSF gcc.

If you change symlinks in /usr/bin/cc, MacPorts will still try to use flags which are only understood by the Apple version. This could make it impossible to compile anything using MacPorts.

Just trust the MacPorts developers that using Apple provided compilers is the best way.

Answer 3

Set configure.compiler variable in Portfile accordingly:

configure.compiler    macports-gcc-4.3

or append configure.compiler=macports-gcc-4.3 to your command.

cf. this wiki page.