Add a Python 3 warning about accessing sys.maxint (#1180)

CONTRIBUTORS.txt

@@ -112,6 +112,7 @@ Order doesn't matter (not that much, at least ;)
 * Roy Williams (Lyft): added check for implementing __eq__ without implementing __hash__,
   Added Python 3 check for accessing Exception.message,
   Added Python 3 check for calling encode/decode with invalid codecs.
+  Added Python 3 check for accessing sys.maxint
 
 * Erik Eriksson - Added overlapping-except error check.
 

ChangeLog

@@ -200,6 +200,9 @@ Release date: tba
 
       Closes #1166
 
+    * Added a new Python 3 check for accessing 'sys.maxint' which was removed in Python 3 in favor
+      of 'sys.maxsize'
+
 
 What's new in Pylint 1.6.3?
 ===========================

doc/whatsnew/2.0.rst

@@ -293,6 +293,22 @@ New checkers
       except (ConnectionError, IOError, OSError, socket.error):
           pass
 
+* A new Python 3 checker was added to warn about accessing ``sys.maxint``.  This attribute was
+  removed in Python 3 in favor of ``sys.maxsize``.
+
+  .. code-block:: python
+
+      import sys
+      print(sys.maxint)
+
+  Instead of using ``sys.maxint``, use ``sys.maxsize``
+
+  .. code-block:: python
+
+      import sys
+      print(sys.maxsize)
+
+
 Other Changes
 =============
 

pylint/checkers/python3.py

@@ -367,6 +367,10 @@ class Python3Checker(checkers.BaseChecker):
                   'Used when using str.encode or str.decode with a non-text encoding.  Use '
                   'codecs module to handle arbitrary codecs.',
                   {'maxversion': (3, 0)}),
+        'W1647': ('sys.maxint removed in Python 3',
+                  'sys-max-int',
+                  'Used when accessing sys.maxint.  Use sys.maxsize instead.',
+                  {'maxversion': (3, 0)}),
     }
 
     _bad_builtins = frozenset([
@@ -591,11 +595,13 @@ def visit_attribute(self, node):
         """ Look for accessing message on exceptions. """
         try:
             for infered in node.expr.infer():
-                if not isinstance(infered, astroid.Instance):
-                    continue
-                if utils.inherit_from_std_ex(infered):
+                if (isinstance(infered, astroid.Instance) and
+                        utils.inherit_from_std_ex(infered)):
                     if node.attrname == 'message':
                         self.add_message('exception-message-attribute', node=node)
+                if isinstance(infered, astroid.Module) and infered.name == 'sys':
+                    if node.attrname == 'maxint':
+                        self.add_message('sys-max-int', node=node)
         except astroid.InferenceError:
             return
 

pylint/test/unittest_checker_python3.py

@@ -491,6 +491,24 @@ def test_using_cmp_argument(self):
             with self.assertAddsMessages(message):
                 self.checker.visit_call(node)
 
+    @python2_only
+    def test_sys_maxint(self):
+        node = astroid.extract_node('''
+        import sys
+        sys.maxint #@
+        ''')
+        message = testutils.Message('sys-max-int', node=node)
+        with self.assertAddsMessages(message):
+            self.checker.visit_attribute(node)
+
+    @python2_only
+    def test_object_maxint(self):
+        node = astroid.extract_node('''
+        sys = object()
+        sys.maxint #@
+        ''')
+        with self.assertNoMessages():
+            self.checker.visit_attribute(node)
 
 @python2_only
 class Python3TokenCheckerTest(testutils.CheckerTestCase):