Ignore additional complex duplicate-key cases

Makefile

@@ -1,11 +1,11 @@
 check:
-	pyflakes ./*.py
+	pyflakes autoflake.py setup.py test_autoflake.py
 	pylint \
 		--reports=no \
 		--rcfile=/dev/null \
 		--errors-only \
 		autoflake.py setup.py
-	pycodestyle ./*.py
+	pycodestyle autoflake.py setup.py test_autoflake.py
 	pydocstyle autoflake.py setup.py
 	check-manifest
 	python setup.py --long-description | rstcheck -

autoflake.py

@@ -344,6 +344,11 @@ def filter_code(source, additional_imports=None,
     if remove_duplicate_keys:
         marked_key_line_numbers = frozenset(
             duplicate_key_line_numbers(messages))
+        if (
+            marked_key_line_numbers and
+            any_complex_duplicate_key_cases(marked_key_line_numbers, source)
+        ):
+            marked_key_line_numbers = frozenset()
     else:
         marked_key_line_numbers = frozenset()
 
@@ -375,6 +380,22 @@ def filter_code(source, additional_imports=None,
         previous_line = line
 
 
+def any_complex_duplicate_key_cases(marked_line_numbers, source):
+    """Return True if duplicate key lines contain complex code.
+
+    We don't want to bother trying to parse this stuff and get it right.
+    """
+    lines = source.split('\n')
+    for line_number in marked_line_numbers:
+        line = lines[line_number - 1]
+
+        if line.rstrip().endswith((':', '\\')):
+            return True
+
+        if ':' not in line or '#' in line:
+            return True
+
+
 def get_messages_by_line(messages):
     """Return dictionary that maps line number to message."""
     line_messages = {}
@@ -467,9 +488,9 @@ def is_last_in_object(line, line_number, key, marked_line_numbers, source):
         source
     )
 
-    if len(obj_lines) <= 1:
-        # This means it is too complex for us to parse. Keep the item by
-        # assuming it is the last item.
+    if obj_lines is None or len(obj_lines) <= 1:
+        # We failed to parse something. Don't touch. Keep the item by assuming
+        # it is the last item.
         return True
 
     if line_number == obj_lines[-1]:
@@ -481,6 +502,8 @@ def is_last_in_object(line, line_number, key, marked_line_numbers, source):
 def dict_entry_has_key(line, key):
     """Return True if `line` is a dict entry that uses `key`."""
     result = re.match(r'\s*(.*)\s*:.*,?\s*$', line)
+    if not result:
+        return False
 
     try:
         candidate_key = ast.literal_eval(result.group(1))

test_autoflake.py

@@ -457,6 +457,41 @@ def test_filter_code_should_ignore_complex_case_of_duplicate_key(self):
   (0,1): 3,
 }
 print(a)
+"""
+
+        self.assertEqual(
+            code,
+            ''.join(autoflake.filter_code(code,
+                                          remove_duplicate_keys=True)))
+
+    def test_filter_code_should_ignore_more_cases_of_duplicate_key(self):
+        """We only handle simple cases."""
+        code = """\
+a = {
+    (0,1):
+    1,
+    (0, 1): 'two',
+  (0,1): 3,
+}
+print(a)
+"""
+
+        self.assertEqual(
+            code,
+            ''.join(autoflake.filter_code(code,
+                                          remove_duplicate_keys=True)))
+
+    def test_filter_code_should_ignore_duplicate_key_with_comments(self):
+        """We only handle simple cases."""
+        code = """\
+a = {
+    (0,1)  # : f
+    :
+    1,
+    (0, 1): 'two',
+  (0,1): 3,
+}
+print(a)
 """
 
         self.assertEqual(