Support APPLE and LINUX platforms in CPP Preprocessing

[Shaikh-Ubaid]

fixes #3217

[Shaikh-Ubaid]

Output of the added test on MacOS:

% lfortran integration_tests/cpp_pre_03.f90 --cpp
OSX
Ok

[Shaikh-Ubaid]

Also see #3217 (comment).

[certik]

Let's also add other C++ defines, here is our relevant code:

Platform get_platform()
{
#if defined(_WIN32)                                           
    return Platform::Windows;
#elif defined(__APPLE__)                                               
#    ifdef __aarch64__       
    return Platform::macOS_ARM;
#    else                                          
    return Platform::macOS_Intel;  
#    endif
#elif defined(__FreeBSD__)      
    return Platform::FreeBSD;
#elif defined(__OpenBSD__)            
    return Platform::OpenBSD;     
#else
    return Platform::Linux;                 
#endif          
}

So let's add:

__FreeBSD__
__OpenBSD__

and also platform defines:

__aarch64__
__x86_64__

That should cover most cases.

[Shaikh-Ubaid]

Sure. Added.

% cat integration_tests/cpp_pre_03.f90 
program cpp_pre_03
#ifdef _WIN32
    print *,"Windows"
#endif
#ifdef __linux__
    print *,"Linux"
#endif
#ifdef __APPLE__
    print *,"OSX"
#endif
#ifdef __aarch64__
    print *,"Apple ARM"
#endif
#ifdef __x86_64__
    print *,"Apple AMD"
#endif
#ifdef __FreeBSD__
    print *,"FreeBSD"
#endif
#ifdef __OpenBSD__
    print *,"OpenBSD"
#endif
print *, "Ok"
end program
% gfortran integration_tests/cpp_pre_03.f90 -cpp
% ./a.out 
 Ok
% lfortran integration_tests/cpp_pre_03.f90 --cpp
OSX
Apple ARM
Ok

[certik]

I think that this is good. We'll have to eventually revamp how we handle the architecture / platform "triplet", since linux can also be "arm", and so on. But for now this is good to get us started.

Thanks!

[junghans]

I think we also need to define this on Linux.