How to compile distributable Fortran binaries on Mac OS X Mountain Lion?

Question

Since Apple have stopped distributing gfortran with Xcode, how should I compile architecture independent Fortran code? I have Mac OS X Mountain Lion (10.8), and XCode 4.4 installed, with the Command Line Tools package installed.

Apple's Native Compilers

As far as I can tell, the Xcode C / C++ / ObjC compilers use a fork of the GNU compiler collection, with llvm as a backend; the latter I figure enables compiling and optimising "universal" binaries, for both Intel and PPC architectures.

3rd party binary Fortran compilers

HPC

I've only found a single website that distributes a binary version of gfortran specifically for Mountain Lion: the HPC website. However, I failed to get this to compile SciPy, and later saw in SciPy's README that it is "known to generate buggy scipy binaries".

CRAN/R

SciPy's recommended (free) Fortran compiler is the one on CRAN's R server, but this has not been updated for Mountain Lion yet. They provide instructions and a script for Building a Universal Compiler, but, again, this hasn't been updated for Mountain Lion yet..

G95

The G95 project hasn't had an update since 2010, so I didn't try it.. Anyone tried this on Mountain Lion?

MacPorts

I guess this will be the easiest way to get gfortran installed, but port search gfortran comes up with nothing, and I've not had any joy with MacPorts in the past (no offence to MacPorts; it's looks like a very active project, but I've been spoilt with Linux package managers, my favourite manager being aptitude) so on Mac OS X I've compiled software and libraries from source code in the past. Never been a problem 'til now...

Building a Fortran compiler

Having dug around on the internet a lot in the last couple of days, I've found other Fortran compilers, but I've failed to get any to cross-compile universal binaries, or to compile SciPy.

GCC - The Gnu Compiler Collection

I compiled the entire GCC collection (v4.6.3), including autotools, automake, libtool and m4 - like the GCC wiki and this blog describe - but the resulting compilers didn't compile universal binaries, probably because LLVM wasn't used as a backend.

DragonEgg

DragonEgg is a "gcc plugin that replaces GCC's optimisers and code-generators ... with LLVM". This looks interesting, but I don't know how I could use it to compile 'llvm-gfortran-4.x'. Can this be done?

Compatibility

Libraries

The compiler that comes with Xcode is (a fork of?) GCC v4.2. But GCC's current release and development branches are versions 4.6 and 4.7, respectively. Apparently, a GNU license change, or something, stopped Apple from updating to more modern versions of GCC. So, if I was to build dynamic libraries made with GCC's gfortran v4.6, could they then be linked with C code compiled by Xcode's native compiler? At a minimum, I figure resulting Mach-O binaries need both x86_64 and i386 code paths. Do GCC provide backwards compatibility with Apple's (forks of?) GCC? I know gfortran has the -ff2c flag, but is this stable across versions?

Compile flags

The GCC Fortran compiler I built from source didn't support the use of the -arch compile flag. I had been including the flags -arch x86_64 -arch i386 in both CFLAGS and FFLAGS environment variables on earlier OSX versions (Snow Leopard to Lion). Python's distutils, and probably other OSX compilers, expect these flags to work, when configured to build apps or frameworks, using Xcode's universal SDK.

In case you're wondering what compile flags I use, I've uploaded the script I use to pastebin, which I source before I compile anything, using: source ~/.bash_devenv.

The Ideal OSX Fortran Compiler

• Create ppc and intel (32 and 64bit) universal binaries, specified by using the -arch flags.
• Makes binaries compatible with XCode's linker.
• Compiles SciPy, giving no errors (compatible with numpy's distutils and f2py).

I don't use Xcode so much, but integration with it would surely benefit other users. Even Intel are still having problems integrating ifort into Xcode 4.4, so this is not something I expect to work..

If you read all the above, then thank you! You can probably tell that I'm not averse to building my own Fortran compiler from source, but is it even possible? Have I missed something? A configure flag maybe? And if such a compiler is not available yet, then why not?!

(Update:) Apple's GCC

Apple provide the source code for their patched version of GCC, at opensource.apple.com. This actually includes the source code for gfortran, but what do you know - it doesn't compile (easily). I'm in the process of writing a build script to get this to work. Unfortunately, I've had to apply a couple of patches, and learn about "the Apple way" of building GNU software. This is the way to go I think. Any reasons why it shouldn't be? I'll update with an answer if I get it to work...

Answer 1

I managed to compile after installing gfortran from http://r.research.att.com/tools/gcc-42-5666.3-darwin11.pkg, as explained here. I had to try to open the package a couple of times, though. First time it said that only apps from App Store can be installed. After installing gfortran, python setup.py build and python setup.py install worked fine. The unit tests of scipy though give a fairly high number of fails, not sure it's normal.

Ran 5481 tests in 82.079s

FAILED (KNOWNFAIL=13, SKIP=42, errors=11, failures=72)
<nose.result.TextTestResult run=5481 errors=11 failures=72>