Do not crash when printing the help of options with default regular expressions

Close #990

3 files changed, 14 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 4be06112c..2e4f95386 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,15 @@
 Pylint NEWS
 -----------
 
+What's new in Pylint 1.6.2?
+===========================
+
+Release date: TBA
+
+    * Do not crash when printing the help of options with default regular expressions
+
+      Close #990
+
 What's new in Pylint 1.6.1?
 ===========================
 
diff --git a/pylint/test/test_self.py b/pylint/test/test_self.py
index 748d81a9f..2d85bddbe 100644
--- a/pylint/test/test_self.py
+++ b/pylint/test/test_self.py
@@ -345,6 +345,10 @@ class RunTC(unittest.TestCase):
         self._test_output([path, "--rcfile=%s" % config_path],
                           expected_output=expected)
 
+    def test_no_crash_with_formatting_regex_defaults(self):
+        self._runtest(["--ignore-patterns=a"], reporter=TextReporter(six.StringIO()),
+                      code=32)
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/pylint/utils.py b/pylint/utils.py
index 75e0ff3c9..a4152c8d2 100644
--- a/pylint/utils.py
+++ b/pylint/utils.py
@@ -1089,7 +1089,7 @@ def _comment(string):
 def _format_option_value(optdict, value):
     """return the user input's value from a 'compiled' value"""
     if isinstance(value, (list, tuple)):
-        value = ','.join(value)
+        value = ','.join(_format_option_value(optdict, item) for item in value)
     elif isinstance(value, dict):
         value = ','.join('%s:%s' % (k, v) for k, v in value.items())
     elif hasattr(value, 'match'): # optdict.get('type') == 'regexp'