Are clang++ and libc++ compatible?

[Tijl Coosemans]

On Tue, 12 Nov 2013 14:40:42 -0800 Steve Kargl wrote:
> On Tue, Nov 12, 2013 at 10:19:46PM +0100, Tijl Coosemans wrote:
>> On Tue, 12 Nov 2013 12:19:22 -0800 Steve Kargl wrote:
>>> This can't be good.  And, unfortunately, testing math/octave shows
>>> no better :(
>>> 
>>> % octave
>>> Segmentation fault (core dumped)
>>> % ldd /usr/local/bin/octave-3.6.4 | grep ++
>>>         libstdc++.so.6 => /usr/local/lib/gcc46/libstdc++.so.6 (0x3c92ec000)
>>>         libc++.so.1 => /usr/lib/libc++.so.1 (0x3c9801000)
>> 
>> This could be because you enabled the OPENMP option in math/fftw3.
> 
> Unfortuantely, that's not it. Just rebuilt fftw3 and octave still
> dies.  ldd shows that /usr/local/lib/octave/3.6.4/liboctinterp.so.1
> is bringing in both libc++ and libstdc++, but it is also linked
> to 52 other libraries.

USE_FORTRAN=yes currently implies USE_GCC=yes so the C++ code in
math/octave links with libstdc++ while dependencies link with libc++.
Gerald, is it possible to separate USE_FORTRAN from USE_GCC?