Extract a method for customizing the compiler for macOS.

Author: jaraco

distutils/sysconfig.py

@@ -266,29 +266,35 @@ def get_python_lib(plat_specific=0, standard_lib=0, prefix=None):
         )
 
 
+def _customize_macos():
+    if sys.platform != "darwin":
+        return
+
+    # Perform first-time customization of compiler-related
+    # config vars on OS X now that we know we need a compiler.
+    # This is primarily to support Pythons from binary
+    # installers.  The kind and paths to build tools on
+    # the user system may vary significantly from the system
+    # that Python itself was built on.  Also the user OS
+    # version and build tools may not support the same set
+    # of CPU architectures for universal builds.
+    global _config_vars
+    # Use get_config_var() to ensure _config_vars is initialized.
+    if not get_config_var('CUSTOMIZED_OSX_COMPILER'):
+        import _osx_support
+
+        _osx_support.customize_compiler(_config_vars)
+        _config_vars['CUSTOMIZED_OSX_COMPILER'] = 'True'
+
+
 def customize_compiler(compiler):  # noqa: C901
     """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":
-        if sys.platform == "darwin":
-            # Perform first-time customization of compiler-related
-            # config vars on OS X now that we know we need a compiler.
-            # This is primarily to support Pythons from binary
-            # installers.  The kind and paths to build tools on
-            # the user system may vary significantly from the system
-            # that Python itself was built on.  Also the user OS
-            # version and build tools may not support the same set
-            # of CPU architectures for universal builds.
-            global _config_vars
-            # Use get_config_var() to ensure _config_vars is initialized.
-            if not get_config_var('CUSTOMIZED_OSX_COMPILER'):
-                import _osx_support
-
-                _osx_support.customize_compiler(_config_vars)
-                _config_vars['CUSTOMIZED_OSX_COMPILER'] = 'True'
+        _customize_macos()
 
         (
             cc,