Backport config file parsing behavior from Python 3.7. Ref #889.

setuptools/dist.py

@@ -21,6 +21,7 @@ from setuptools import windows_support
 from setuptools.monkey import get_unpatched
 from setuptools.config import parse_configuration
 import pkg_resources
+from .py36compat import Distribution_parse_config_files
 
 
 def _get_unpatched(cls):
@@ -213,7 +214,7 @@ def check_packages(dist, attr, value):
 _Distribution = get_unpatched(distutils.core.Distribution)
 
 
-class Distribution(_Distribution):
+class Distribution(Distribution_parse_config_files, _Distribution):
     """Distribution with support for features, tests, and package data
 
     This is an enhanced version of 'distutils.dist.Distribution' that

setuptools/py36compat.py

+import sys
+from distutils.errors import DistutilsOptionError
+from distutils.util import strtobool
+from distutils.debug import DEBUG
+
+
+class Distribution_parse_config_files:
+    """
+    Mix-in providing forward-compatibility for functionality to be
+    included by default on Python 3.7.
+
+    Do not edit the code in this class except to update functionality
+    as implemented in distutils.
+    """
+    def parse_config_files(self, filenames=None):
+        from configparser import ConfigParser
+
+        # Ignore install directory options if we have a venv
+        if sys.prefix != sys.base_prefix:
+            ignore_options = [
+                'install-base', 'install-platbase', 'install-lib',
+                'install-platlib', 'install-purelib', 'install-headers',
+                'install-scripts', 'install-data', 'prefix', 'exec-prefix',
+                'home', 'user', 'root']
+        else:
+            ignore_options = []
+
+        ignore_options = frozenset(ignore_options)
+
+        if filenames is None:
+            filenames = self.find_config_files()
+
+        if DEBUG:
+            self.announce("Distribution.parse_config_files():")
+
+        parser = ConfigParser()
+        for filename in filenames:
+            if DEBUG:
+                self.announce("  reading %s" % filename)
+            parser.read(filename)
+            for section in parser.sections():
+                options = parser.options(section)
+                opt_dict = self.get_option_dict(section)
+
+                for opt in options:
+                    if opt != '__name__' and opt not in ignore_options:
+                        val = parser.get(section,opt)
+                        opt = opt.replace('-', '_')
+                        opt_dict[opt] = (filename, val)
+
+            # Make the ConfigParser forget everything (so we retain
+            # the original filenames that options come from)
+            parser.__init__()
+
+        # If there was a "global" section in the config file, use it
+        # to set Distribution options.
+
+        if 'global' in self.command_options:
+            for (opt, (src, val)) in self.command_options['global'].items():
+                alias = self.negative_opt.get(opt)
+                try:
+                    if alias:
+                        setattr(self, alias, not strtobool(val))
+                    elif opt in ('verbose', 'dry_run'): # ugh!
+                        setattr(self, opt, strtobool(val))
+                    else:
+                        setattr(self, opt, val)
+                except ValueError as msg:
+                    raise DistutilsOptionError(msg)
+
+
+if sys.version_info < (3,):
+    # Python 2 behavior is sufficient
+    class Distribution_parse_config_files:
+        pass
+
+
+if False:
+    # When updated behavior is available upstream,
+    # disable override here.
+    class Distribution_parse_config_files:
+        pass