code: def add_common_cc_variables(env):
      
      if '_CCCOMCOM' not in env:
          env['_CCCOMCOM'] = '$CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS'
          # It's a hack to test for darwin here, but the alternative
          # of creating an applecc.py to contain this seems overkill.
          # Maybe someday the Apple platform will require more setup and
          # this logic will be moved.
          env['FRAMEWORKS'] = SCons.Util.CLVar('')
          env['FRAMEWORKPATH'] = SCons.Util.CLVar('')
          if env['PLATFORM'] == 'darwin':
              env['_CCCOMCOM'] = env['_CCCOMCOM'] + ' $_FRAMEWORKPATH'
  
      if 'CCFLAGS' not in env:
          env['CCFLAGS']   = SCons.Util.CLVar('')
  
      if 'SHCCFLAGS' not in env:
          env['SHCCFLAGS'] = SCons.Util.CLVar('$CCFLAGS')
docs: Add underlying common "C compiler" variables that
      are used by multiple tools (specifically, c++).