[Distutils] mingw and environment variables

[Dobes Vandermeer]

It seems to be a problem with distutils currently that g++ isn't used to  
link at the appropriate time.  Ideally you'd split linking into C++ and C  
variations, and detect whether the C++ compiler was used and use the  
C++ linker if it was.

And, a bug related to this, is that you can't easily override the linker  
when using mingw; the customize_compiler() function checks for a type of  
'unix':

def customize_compiler(compiler):
     """Do any platform-specific customization of a CCompiler instance.

     Mainly needed on Unix, so we can plug in the information that
     varies across Unices and is stored in Python's Makefile.
     """
     if compiler.compiler_type == "unix":

But the mingw compiler (which is unix compatible) has a compiler_type  
'mingw32', not 'unix'.

The easiest "band-aid" patch would be to use

if compiler.compiler_type in ("unix", "mingw32"):

but I wonder whether:

if isinstance(compiler, UnixCCompiler):

would be more appropriate?


The workaround I came up with is:

# Force g++ for linking
import distutils.sysconfig
old_customize_compiler = distutils.sysconfig.customize_compiler
def customize_compiler(compiler):
     old_customize_compiler(compiler)
     if compiler.compiler_type == 'mingw':
        compiler.set_executables(linker_so='g++ -mno-cygwin -shared')
distutils.sysconfig.customize_compiler = customize_compiler