Fix false positive E711/E712; issue #336

3 files changed, 13 insertions, 10 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 79a3454..3427e9b 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -36,6 +36,8 @@ Bug fixes:
 
 * Don't crash if os.path.expanduser() throws an ImportError. (Issue #297)
 
+* Fix false positive E711/E712. (Issue #336)
+
 
 1.5.7 (2014-05-29)
 ------------------
diff --git a/pep8.py b/pep8.py
index 6f6a4c4..7a50ab3 100755
--- a/pep8.py
+++ b/pep8.py
@@ -106,10 +106,8 @@ ERRORCODE_REGEX = re.compile(r'\b[A-Z]\d{3}\b')
 DOCSTRING_REGEX = re.compile(r'u?r?["\']')
 EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')
 WHITESPACE_AFTER_COMMA_REGEX = re.compile(r'[,;:]\s*(?:  |\t)')
-COMPARE_SINGLETON_REGEX = re.compile(r'(?P<op>[=!]=)\s*'
-                                     r'(?P<singleton>None|False|True)')
-COMPARE_SINGLETON_REVERSE_REGEX = re.compile(r'(?P<singleton>None|False|True)'
-                                             r'\s*(?P<op>[=!]=)')
+COMPARE_SINGLETON_REGEX = re.compile(r'\b(None|False|True)?\s*([=!]=)'
+                                     r'\s*(?(1)|(None|False|True))\b')
 COMPARE_NEGATIVE_REGEX = re.compile(r'\b(not)\s+[^[({ ]+\s+(in|is)\s')
 COMPARE_TYPE_REGEX = re.compile(r'(?:[=!]=|is(?:\s+not)?)\s*type(?:s.\w+Type'
                                 r'|\s*\(\s*([^)]*[^ )])\s*\))')
@@ -998,12 +996,10 @@ def comparison_to_singleton(logical_line, noqa):
     set to some other value.  The other value might have a type (such as a
     container) that could be false in a boolean context!
     """
-
-    match = not noqa and (COMPARE_SINGLETON_REGEX.search(logical_line) or
-                          COMPARE_SINGLETON_REVERSE_REGEX.search(logical_line))
+    match = not noqa and COMPARE_SINGLETON_REGEX.search(logical_line)
     if match:
-        singleton = match.group('singleton')
-        same = (match.group('op') == '==')
+        singleton = match.group(1) or match.group(3)
+        same = (match.group(2) == '==')
 
         msg = "'if cond is %s:'" % (('' if same else 'not ') + singleton)
         if singleton in ('None',):
@@ -1013,7 +1009,7 @@ def comparison_to_singleton(logical_line, noqa):
             nonzero = ((singleton == 'True' and same) or
                        (singleton == 'False' and not same))
             msg += " or 'if %scond:'" % ('' if nonzero else 'not ')
-        yield match.start(1), ("%s comparison to %s should be %s" %
+        yield match.start(2), ("%s comparison to %s should be %s" %
                                (code, singleton, msg))
 
 
diff --git a/testsuite/E71.py b/testsuite/E71.py
index 3f07b1a..25a308f 100644
--- a/testsuite/E71.py
+++ b/testsuite/E71.py
@@ -55,4 +55,9 @@ if not (X in Y):
     pass
 if x is not y:
     pass
+
+if TrueElement.get_element(True) == TrueElement.get_element(False):
+    pass
+if (True) == TrueElement or x == TrueElement:
+    pass
 #: