[SciPy-dev] Mac OS X and gcc 4.2

[David M. Cooke]

On Fri, Aug 18, 2006 at 11:46:24AM +1000, Bill Northcott wrote:
> On 18/08/2006, at 3:00 AM, Chris Kees wrote:
> > having trouble  even building the trunk of numpy and  scipy on Mac
> > OS  X using a  recent build of gcc  (version 4.2.0 20060710) .
> 
> Why use such a bleeding edge compiler?

On Intel Macs, you *need* the latest for gfortran (within in the last
several months, at least).

> The FSF compilers don't even work very well on Darwin, which is only  
> of secondary interest to the FSF developers.  OTOH Apple incorporate  
> a number of Darwin optimisations into their code which does not reach  
> the FSF sources until later if at all.  Even worse current Apple  
> compilers are based on gcc-4.0.x so a lot of Apple stuff will be in  
> FSF 4.0.3 but none of it in 4.2 which is very different.
> 
> You can use the standard Apple compilers with a Fortran from  
> hpc.sourceforge.net.  Or just get the current R 2.3.1 binary package  
> which includes gcc-4.0.3 with gfortran.  Although this appears to be  
> built from FSF sources it is universal and can target i386, ppc and  
> ppc64.

Note that the gfortran from hpc.sf.net was built August 2006 -- it is a
bleeding edge compiler :)

> 
> > errors with gcc 4.2:
> >
> > ...
> > gcc: _configtest.c
> > gcc: unrecognized option '-no-cpp-precomp'
> > cc1: error: unrecognized command line option "-arch"
> > cc1: error: unrecognized command line option "-arch"
> > cc1: error: unrecognized command line option "-Wno-long-double"
> 
> As others have observed the problem is the configure script.   As the  
> autoconf macro guidelines make clear one should test for features not  
> software versions.  The script clearly tests for Darwin and assumes  
> an Apple compiler.  The options causing the errors are all Apple  
> specific.
> 
> I think the -no-cpp-precomp option is now redundant, -arch is only  
> necessary if you are trying to target a different architecture to the  
> build host.  I am surprised it is used at all.  While -Wno-long- 
> double is sort of important.  The size of long doubles has changed  
> recently on Darwin so it is useful to now if you have them in your code.

The problem is these options come from the Python distutils, which is
expecting that extensions are built with the same compiler that it was
built with. I've run into the same problems with using gcc and Compaq
cc on an Alpha machine :)

For numpy.distutils, we could add something for this. It's on my list :D

-- 
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|David M. Cooke                      http://arbutus.physics.mcmaster.ca/dmc/
|cookedm at physics.mcmaster.ca