Warn when calling dict.iter*(), dict.view*() or .next() on any object.

These methods either do not exist in Python 3 or are never used.

4 files changed, 78 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index 2d7eef2..20a8c0d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -142,15 +142,21 @@ ChangeLog for Pylint
     * 'too-many-lines' disable pragma can be located on any line, not only the
       first. Closes issue #321.
 
-    * Warn in Python 2.7 when an import statement is found without a
+    * Warn in Python 2 when an import statement is found without a
       corresponding `from __future__ import absolute_import`.
 
-    * Warn in Python 2.7 when a non-floor division operation is found without
+    * Warn in Python 2 when a non-floor division operation is found without
       a corresponding `from __future__ import division`.
 
     * Add a new option, 'exclude-protected', for excluding members
       from the protected-access warning. Closes issue #48.
 
+    * Warn in Python 2 when using dict.iter*(), dict.view*(); none of these
+      methods are available in Python 3.
+
+    * Warn in Python 2 when calling an object's next() method; Python 3 uses
+      __next__() instead.
+
 
 2014-07-26  --  1.3.0
 
diff --git a/checkers/python3.py b/checkers/python3.py
index 5a3d245..d055638 100644
--- a/checkers/python3.py
+++ b/checkers/python3.py
@@ -130,6 +130,21 @@ class Python3Checker(checkers.BaseChecker):
                   '``from __future__ import division``'
                   '(Python 3 returns a float for int division unconditionally)',
                   {'maxversion': (3, 0)}),
+        'W1620': ('Calling a dict.iter*() method',
+                  'dict-iter-method',
+                  'Used for calls to dict.iterkeys(), itervalues() or iteritems() '
+                  '(Python 3 lacks these methods)',
+                  {'maxversion': (3, 0)}),
+        'W1621': ('Calling a dict.view*() method',
+                  'dict-view-method',
+                  'Used for calls to dict.viewkeys(), viewvalues() or viewitems() '
+                  '(Python 3 lacks these methods)',
+                  {'maxversion': (3, 0)}),
+        'W1622': ('Called a next() method on an object',
+                  'next-method-called',
+                  "Used when an object's next() method is called "
+                  '(Python 3 uses the next() built-in function)',
+                  {'maxversion': (3, 0)}),
     }
 
     _missing_builtins = frozenset([
@@ -204,6 +219,16 @@ class Python3Checker(checkers.BaseChecker):
             else:
                 self.add_message('old-division', node=node)
 
+    def visit_callfunc(self, node):
+        if hasattr(node.func, 'attrname'):
+            if not any([node.args, node.starargs, node.kwargs]):
+                if node.func.attrname in ('iterkeys', 'itervalues', 'iteritems'):
+                    self.add_message('dict-iter-method', node=node)
+                elif node.func.attrname in ('viewkeys', 'viewvalues', 'viewitems'):
+                    self.add_message('dict-view-method', node=node)
+                elif node.func.attrname == 'next':
+                    self.add_message('next-method-called', node=node)
+
 
 def register(linter):
     linter.register_checker(Python3Checker(linter))
diff --git a/test/input/func_noerror_crash_122793.py b/test/input/func_noerror_crash_122793.py
index 1d14d8e..2bb3d2e 100644
--- a/test/input/func_noerror_crash_122793.py
+++ b/test/input/func_noerror_crash_122793.py
@@ -6,4 +6,4 @@ def gen():
     yield
 
 GEN = gen()
-GEN.next()
+next(GEN)
diff --git a/test/unittest_checker_python3.py b/test/unittest_checker_python3.py
index 03ad66b..4ce485f 100644
--- a/test/unittest_checker_python3.py
+++ b/test/unittest_checker_python3.py
@@ -173,6 +173,50 @@ class Python3CheckerTest(testutils.CheckerTestCase):
             for node in (left_node, right_node):
                 self.checker.visit_binop(node)
 
+    def test_dict_iter_method(self):
+        for meth in ('keys', 'values', 'items'):
+            node = test_utils.extract_node('x.iter%s()  #@' % meth)
+            message = testutils.Message('dict-iter-method', node=node)
+            with self.assertAddsMessages(message):
+                self.checker.visit_callfunc(node)
+
+    def test_dict_not_iter_method(self):
+        arg_node = test_utils.extract_node('x.iterkeys(x)  #@')
+        stararg_node = test_utils.extract_node('x.iterkeys(*x)  #@')
+        kwarg_node = test_utils.extract_node('x.iterkeys(y=x)  #@')
+        with self.assertNoMessages():
+            for node in (arg_node, stararg_node, kwarg_node):
+                self.checker.visit_callfunc(node)
+
+    def test_dict_view_method(self):
+        for meth in ('keys', 'values', 'items'):
+            node = test_utils.extract_node('x.view%s()  #@' % meth)
+            message = testutils.Message('dict-view-method', node=node)
+            with self.assertAddsMessages(message):
+                self.checker.visit_callfunc(node)
+
+    def test_dict_not_view_method(self):
+        arg_node = test_utils.extract_node('x.viewkeys(x)  #@')
+        stararg_node = test_utils.extract_node('x.viewkeys(*x)  #@')
+        kwarg_node = test_utils.extract_node('x.viewkeys(y=x)  #@')
+        with self.assertNoMessages():
+            for node in (arg_node, stararg_node, kwarg_node):
+                self.checker.visit_callfunc(node)
+
+    def test_next_method(self):
+        node = test_utils.extract_node('x.next()  #@')
+        message = testutils.Message('next-method-called', node=node)
+        with self.assertAddsMessages(message):
+            self.checker.visit_callfunc(node)
+
+    def test_not_next_method(self):
+        arg_node = test_utils.extract_node('x.next(x)  #@')
+        stararg_node = test_utils.extract_node('x.next(*x)  #@')
+        kwarg_node = test_utils.extract_node('x.next(y=x)  #@')
+        with self.assertNoMessages():
+            for node in (arg_node, stararg_node, kwarg_node):
+                self.checker.visit_callfunc(node)
+
 
 if __name__ == '__main__':
     unittest.main()