[petsc-dev] defaulting gnu compilers on Apple

[Satish Balay]

On Thu, 31 Oct 2013, Satish Balay wrote:

> On Thu, 31 Oct 2013, Barry Smith wrote:
> 
> > > As of now - the differences this wrapper might provide is not obvious to us.
> > > 
> > > So for practical purposes '/usr/bin/gcc' is same as 'clang’.
> > 
> >    How can you say that. We simply do not know.
> 
> 1. /usr/bin/gcc says its clang [in verbose mode] 
> 
> Executing: /opt/HPC/mpich-3.0.4-gcc4.2/bin/mpicc --version
> stdout:
> Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
> Target: x86_64-apple-darwin13.0.0
> 
> 2. /usr/bin/gcc says its clang in error messages:


4. Missed mentioning: '/usr/bin/gcc' does not accept GNU-gcc options.
[as indicated below]

Satish

> 
> > ~/s/s/w/tmp ❯❯❯ gcc -fsel-sched-pipelining file.c
> > 
> > clang: warning: argument unused during compilation: '-fsel-sched-pipelining'
> 
> 3. And it accepts clang arguments that gcc does not.
> 
> > ~/s/s/w/tmp ❯❯❯ gcc --analyze file.c
> > ~/s/s/w/tmp ❯❯❯ clang --analyze file.c
> 
> So - I conclude '/usr/bin/gcc' is clang - perhaps with a light-weight
> wrapper [because the binaries don't match.] until someone can show
> there is a difference in behavior in terms of 'works with clang - but
> not with /usr/bin/gcc'
> 
> Satish