Supply a copy of _optim_args_from_interpreter_flags for Python 3.5 co…

…mpatibility. Ref pypa/setuptools#2357.

distutils/py35compat.py

@@ -0,0 +1,19 @@
+import sys
+import subprocess
+
+
+def __optim_args_from_interpreter_flags():
+    """Return a list of command-line arguments reproducing the current
+    optimization settings in sys.flags."""
+    args = []
+    value = sys.flags.optimize
+    if value > 0:
+        args.append("-" + "O" * value)
+    return args
+
+
+_optim_args_from_interpreter_flags = getattr(
+    subprocess,
+    "_optim_args_from_interpreter_flags",
+    __optim_args_from_interpreter_flags,
+)

distutils/util.py

@@ -14,6 +14,8 @@
 from distutils.spawn import spawn
 from distutils import log
 from distutils.errors import DistutilsByteCompileError
+from .py35compat import _optim_args_from_interpreter_flags
+
 
 def get_host_platform():
     """Return a string that identifies the current platform.  This is used mainly to
@@ -420,7 +422,7 @@ def byte_compile (py_files,
 """ % (optimize, force, prefix, base_dir, verbose))
 
         cmd = [sys.executable]
-        cmd.extend(subprocess._optim_args_from_interpreter_flags())
+        cmd.extend(_optim_args_from_interpreter_flags())
         cmd.append(script_name)
         spawn(cmd, dry_run=dry_run)
         execute(os.remove, (script_name,), "removing %s" % script_name,