[cmake-developers] Unsupported "-arch x86_64" mysteriously ends up in Fortran_FLAGS

[Brad King]

On 01/22/2013 02:11 PM, Mojca Miklavec wrote:
> I realised that an unsupported compiler flag "-arch x86_64"
> mysteriously sneaks into Fortran_FLAGS when
>     -DCMAKE_OSX_ARCHITECTURES="x86_64"

The "-arch" flag is hard-coded here:

 http://cmake.org/gitweb?p=cmake.git;a=blob;f=Source/cmLocalGenerator.cxx;hb=v2.8.10.2#l1826

It was added to CMake way back when universal binary support was
first added to OS X under the assumption that all compilers that
would be used in combination with CMAKE_OSX_ARCHITECTURES would
support the flag.  Obviously the assumption is wrong.

The hard-coded flag needs to be replaced with a lookup of a new
per-language platform information variable, perhaps called

 CMAKE_<LANG>_OSX_ARCHITECTURE_FLAG

-Brad