old_contents: import os, sys, shutil
  
  from textwrap import dedent
  import tempfile
  
  import distutils.sysconfig
  import distutils.ccompiler
  from distutils.errors import CompileError, LinkError
  
  
  def check_nix(library_dirs=(), include_dirs=(), compile_args=()):
      """
      Check if NIX is available by trying to compile a tiny program.
      """
  
      cpp_code = dedent("""
      #include <nix.hpp>
  
      int main() {
          return 0;
      }
      """)
  
      tmpdir = tempfile.mkdtemp()
      bin_file_name = os.path.join(tmpdir, "check_nix")
      file_name = bin_file_name + '.cpp'
      with open(file_name, 'w') as cfile:
          cfile.write(cpp_code)
  
      compiler = distutils.ccompiler.new_compiler()
      assert isinstance(compiler, distutils.ccompiler.CCompiler)
  
      distutils.sysconfig.customize_compiler(compiler)
      compiler.initialize()
      compiler.set_library_dirs(library_dirs)
      compiler.set_include_dirs(include_dirs)
  
      stderr = os.dup(sys.stderr.fileno())
      errfile = open(os.path.join(tmpdir, "check_nix.err"), 'w')
      # redirect stderr to file
      os.dup2(errfile.fileno(), sys.stderr.fileno())
      try:
          compiler.compile([file_name], output_dir=tmpdir,
                           extra_postargs=compile_args)
      except (CompileError, LinkError):
          ret_val = False
      else:
          ret_val = True
      # restore stderr
      os.dup2(stderr, sys.stderr.fileno())
      errfile.close()
      shutil.rmtree(tmpdir)
      return ret_val
  
  
  if __name__ == '__main__':
      nix_inc_dir = os.getenv('NIX_INCDIR', '/usr/local/include')
      nix_lib_dir = os.getenv('NIX_LIBDIR', '/usr/local/lib')
      res = check_nix([nix_lib_dir], [nix_inc_dir])
      if res:
          print("Found NIX.")
      else:
          print("NIX not found.")
  
  
  
new_contents: import os, sys, shutil
  
  from textwrap import dedent
  import tempfile
  
  import distutils.sysconfig
  import distutils.ccompiler
  from distutils.errors import CompileError, LinkError
  
  
  def check_nix(library_dirs=(), include_dirs=(), compile_args=()):
      """
      Check if NIX is available by trying to compile a tiny program.
      """
  
      cpp_code = dedent("""
      #include <nix.hpp>
  
      int main() {
          return 0;
      }
      """)
  
      tmpdir = tempfile.mkdtemp()
      bin_file_name = os.path.join(tmpdir, "check_nix")
      file_name = bin_file_name + '.cpp'
      with open(file_name, 'w') as cfile:
          cfile.write(cpp_code)
  
      compiler = distutils.ccompiler.new_compiler()
      assert isinstance(compiler, distutils.ccompiler.CCompiler)
  
      distutils.sysconfig.customize_compiler(compiler)
      compiler.set_library_dirs(library_dirs)
      compiler.set_include_dirs(include_dirs)
  
      stderr = os.dup(sys.stderr.fileno())
      errfile = open(os.path.join(tmpdir, "check_nix.err"), 'w')
      # redirect stderr to file
      os.dup2(errfile.fileno(), sys.stderr.fileno())
      try:
          compiler.compile([file_name], output_dir=tmpdir,
                           extra_postargs=compile_args)
      except (CompileError, LinkError):
          ret_val = False
      else:
          ret_val = True
      # restore stderr
      os.dup2(stderr, sys.stderr.fileno())
      errfile.close()
      shutil.rmtree(tmpdir)
      return ret_val
  
  
  if __name__ == '__main__':
      nix_inc_dir = os.getenv('NIX_INCDIR', '/usr/local/include')
      nix_lib_dir = os.getenv('NIX_LIBDIR', '/usr/local/lib')
      res = check_nix([nix_lib_dir], [nix_inc_dir])
      if res:
          print("Found NIX.")
      else:
          print("NIX not found.")
  
  
  
subject: Remove linux failing initialize since it's not used anymore on win.