Explain configuration options. Issue #82.

2 files changed, 7 insertions, 2 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index d40efe3..98af24c 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -5,6 +5,8 @@ Changelog
 1.x (UNRELEASED)
 ----------------
 
+* Explain which configuration options are expected. (Issue #82)
+
 * Fix wrong or missing cases for the E12 series.
 
 * Fix cases where E122 was missed. (Issue #81)
diff --git a/pep8.py b/pep8.py
index 9289d38..28065c0 100755
--- a/pep8.py
+++ b/pep8.py
@@ -1755,7 +1755,8 @@ def read_config(options, args, arglist, parser):
 
     if config.has_section('pep8'):
         option_list = dict([(o.dest, o.type or o.action)
-                            for o in parser.option_list if o.dest])
+                            for o in parser.option_list if o.dest not in
+                            (None, 'config', 'diff', 'doctest', 'testsuite')])
 
         # First, read the defaut values
         options, _ = parser.parse_args([])
@@ -1764,7 +1765,9 @@ def read_config(options, args, arglist, parser):
         for opt in config.options('pep8'):
             opt_type = option_list.get(opt)
             if not opt_type:
-                print('Unknown option: %s' % opt)
+                print('Unknown option: \'%s\'\n  not in [%s]' %
+                      (opt, ' '.join(sorted(option_list))))
+                sys.exit(1)
             elif opt_type in ('int', 'count'):
                 value = config.getint('pep8', opt)
             elif opt_type == 'string':