[SciPy-dev] Mac OS X and gcc 4.2

[Bill Northcott]

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?

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.

> 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.

Bill Northcott