Warn when parameter unpacking is used as it is not supported in Python

3.

Part of issue #20.

4 files changed, 22 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index a7afafd..516234b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -163,6 +163,9 @@ ChangeLog for Pylint
     * Warn when assigning to __metaclass__ at a class scope; in Python 3 a
       metaclass is specified as an argument to the 'class' statement.
 
+    * Warn when performing parameter tuple unpacking; it is not supported in
+      Python 3.
+
 
 2014-07-26  --  1.3.0
 
diff --git a/checkers/python3.py b/checkers/python3.py
index ca34f09..e7d056d 100644
--- a/checkers/python3.py
+++ b/checkers/python3.py
@@ -44,6 +44,11 @@ class Python3Checker(checkers.BaseChecker):
                   'Used when a print statement is used '
                   '(`print` is a function in Python 3)',
                   {'maxversion': (3, 0)}),
+        'E1602': ('Parameter unpacking specified',
+                  'parameter-unpacking',
+                  'Used when parameter unpacking is specified for a function'
+                  "(Python 3 doesn't allow it)",
+                  {'maxversion': (3, 0)}),
         'W1601': ('apply built-in referenced',
                   'apply-builtin',
                   'Used when the apply built-in function is referenced '
@@ -198,6 +203,12 @@ class Python3Checker(checkers.BaseChecker):
                 method_name = node.name[2:-2]
             self.add_message(method_name + '-method', node=node)
 
+    @utils.check_messages('parameter-unpacking')
+    def visit_arguments(self, node):
+        for arg in node.args:
+            if isinstance(arg, astroid.Tuple):
+                self.add_message('parameter-unpacking', node=arg)
+
     def visit_name(self, node):
         """Detect when a built-in that is missing in Python 3 is referenced."""
         found_node = node.lookup(node.name)[0]
diff --git a/test/functional/defined_and_used_on_same_line.py b/test/functional/defined_and_used_on_same_line.py
index f317ba3..fc19dc7 100644
--- a/test/functional/defined_and_used_on_same_line.py
+++ b/test/functional/defined_and_used_on_same_line.py
@@ -1,5 +1,5 @@
 """Check for definitions and usage happening on the same line."""
-#pylint: disable=missing-docstring,multiple-statements,print-statement,no-absolute-import
+#pylint: disable=missing-docstring,multiple-statements,print-statement,no-absolute-import,parameter-unpacking
 
 print [index
        for index in range(10)]
diff --git a/test/unittest_checker_python3.py b/test/unittest_checker_python3.py
index ecfbc4e..28b152d 100644
--- a/test/unittest_checker_python3.py
+++ b/test/unittest_checker_python3.py
@@ -244,6 +244,13 @@ class Python3CheckerTest(testutils.CheckerTestCase):
         with self.assertNoMessages():
             self.walk(module)
 
+    @python2_only
+    def test_parameter_unpacking(self):
+        node = test_utils.extract_node('def func((a, b)):#@\n pass')
+        arg = node.args.args[0]
+        with self.assertAddsMessages(testutils.Message('parameter-unpacking', node=arg)):
+            self.walk(node)
+
 
 if __name__ == '__main__':
     unittest.main()