old_contents: 
  def pre_build_hook(build_ext, ext):
      from scipy._build_utils.compiler_helper import (
          get_cxx_std_flag, try_add_flag, try_compile, has_flag)
      cc = build_ext._cxx_compiler
      args = ext.extra_compile_args
  
      std_flag = get_cxx_std_flag(build_ext._cxx_compiler)
      if std_flag is not None:
          args.append(std_flag)
  
      if cc.compiler_type == 'msvc':
          args.append('/EHsc')
      else:
          try_add_flag(args, cc, '-fvisibility=hidden')
  
          has_pthreads = try_compile(cc, code='#include <pthread.h>\n'
                                     'int main(int argc, char **argv) {}')
          if has_pthreads:
              ext.define_macros.append(('POCKETFFT_PTHREADS', None))
              if has_flag(cc, '-pthread'):
                  args.append('-pthread')
                  ext.extra_link_args.append('-pthread')
              else:
                  from numpy.distutils import log
                  log.warn('Unknown compiler pthread flag')
  
          min_macos_flag = '-mmacosx-version-min=10.9'
          import sys
          if sys.platform == 'darwin' and has_flag(cc, min_macos_flag):
              args.append(min_macos_flag)
              ext.extra_link_args.append(min_macos_flag)
  
  
  def configuration(parent_package='', top_path=None):
      from numpy.distutils.misc_util import Configuration
      import pybind11
      include_dirs = [pybind11.get_include(True), pybind11.get_include(False)]
  
      config = Configuration('_pocketfft', parent_package, top_path)
      ext = config.add_extension('pypocketfft',
                                 sources=['pypocketfft.cxx'],
                                 depends=['pocketfft_hdronly.h'],
                                 include_dirs=include_dirs,
                                 language='c++')
      ext._pre_build_hook = pre_build_hook
  
      config.add_data_files('LICENSE.md')
      config.add_data_dir('tests')
      return config
  
  
  if __name__ == '__main__':
      from numpy.distutils.core import setup
      setup(**configuration(top_path='').todict())
  
new_contents: 
  def pre_build_hook(build_ext, ext):
      from scipy._build_utils.compiler_helper import (
          get_cxx_std_flag, try_add_flag, try_compile, has_flag)
      cc = build_ext._cxx_compiler
      args = ext.extra_compile_args
  
      std_flag = get_cxx_std_flag(cc)
      if std_flag is not None:
          args.append(std_flag)
  
      if cc.compiler_type == 'msvc':
          args.append('/EHsc')
      else:
          # Use pthreads if available
          has_pthreads = try_compile(cc, code='#include <pthread.h>\n'
                                     'int main(int argc, char **argv) {}')
          if has_pthreads:
              ext.define_macros.append(('POCKETFFT_PTHREADS', None))
              if has_flag(cc, '-pthread'):
                  args.append('-pthread')
                  ext.extra_link_args.append('-pthread')
              else:
                  from numpy.distutils import log
                  log.warn('Unknown compiler pthread flag')
  
          # Don't export library symbols
          try_add_flag(args, cc, '-fvisibility=hidden')
          # Set min macOS version
          min_macos_flag = '-mmacosx-version-min=10.9'
          import sys
          if sys.platform == 'darwin' and has_flag(cc, min_macos_flag):
              args.append(min_macos_flag)
              ext.extra_link_args.append(min_macos_flag)
  
  
  def configuration(parent_package='', top_path=None):
      from numpy.distutils.misc_util import Configuration
      import pybind11
      include_dirs = [pybind11.get_include(True), pybind11.get_include(False)]
  
      config = Configuration('_pocketfft', parent_package, top_path)
      ext = config.add_extension('pypocketfft',
                                 sources=['pypocketfft.cxx'],
                                 depends=['pocketfft_hdronly.h'],
                                 include_dirs=include_dirs,
                                 language='c++')
      ext._pre_build_hook = pre_build_hook
  
      config.add_data_files('LICENSE.md')
      config.add_data_dir('tests')
      return config
  
  
  if __name__ == '__main__':
      from numpy.distutils.core import setup
      setup(**configuration(top_path='').todict())
  
subject: Add some comments to pypocketfft pre build hook