Fix a false positive with unbalanced iterable unpacking, when encountering starred nodes. Closes issue #273.

3 files changed, 22 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index fdc27e1..f56cfe2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -20,6 +20,9 @@ ChangeLog for Pylint
 
     * Emit 'not-callable' when calling properties. Closes issue #268.
 
+    * Fix a false positive with unbalanced iterable unpacking,
+      when encountering starred nodes. Closes issue #273.
+
 2014-04-30  --  1.2.1
     * Restore the ability to specify the init-hook option via the
       configuration file, which was accidentally broken in 1.2.0.
diff --git a/checkers/variables.py b/checkers/variables.py
index dc8d111..b84ad4f 100644
--- a/checkers/variables.py
+++ b/checkers/variables.py
@@ -147,7 +147,7 @@ MSGS = {
               'a sequence is used in an unpack assignment'),
 
     'W0640': ('Cell variable %s defined in loop',
-              'cell-var-from-loop', 
+              'cell-var-from-loop',
               'A variable used in a closure is defined in a loop. '
               'This will result in all closures using the same value for '
               'the closed-over variable.'),
@@ -447,7 +447,7 @@ builtins. Remember that you should avoid to define new builtins when possible.'
             else:
                 if maybe_for.parent_of(node_scope) and not isinstance(node_scope.statement(), astroid.Return):
                     self.add_message('cell-var-from-loop', node=node, args=node.name)
-        
+
     def _loopvar_name(self, node, name):
         # filter variables according to node's scope
         # XXX used to filter parents but don't remember why, and removing this
@@ -649,6 +649,10 @@ builtins. Remember that you should avoid to define new builtins when possible.'
             # attempt to check unpacking is properly balanced
             values = infered.itered()
             if len(targets) != len(values):
+                # Check if we have starred nodes.
+                if any(isinstance(target, astroid.Starred)
+                       for target in targets):
+                    return
                 self.add_message('unbalanced-tuple-unpacking', node=node,
                                  args=(_get_unpacking_extra_info(node, infered),
                                        len(targets),
@@ -727,8 +731,8 @@ class VariablesChecker3k(VariablesChecker):
 
                 if isinstance(klass._metaclass, astroid.Name):
                     module_locals.pop(klass._metaclass.name, None)
-                if metaclass:                
-                    # if it uses a `metaclass=module.Class`                            
+                if metaclass:
+                    # if it uses a `metaclass=module.Class`
                     module_locals.pop(metaclass.root().name, None)
         super(VariablesChecker3k, self).leave_module(node)
 
diff --git a/test/input/func_noerror_unbalanced_tuple_unpacking_py30.py b/test/input/func_noerror_unbalanced_tuple_unpacking_py30.py
new file mode 100644
index 0000000..68f5fb7
--- /dev/null
+++ b/test/input/func_noerror_unbalanced_tuple_unpacking_py30.py
@@ -0,0 +1,11 @@
+""" Test that using starred nodes in unpacking
+does not trigger a false positive on Python 3.
+"""
+
+__revision__ = 1
+
+def test():
+    """ Test that starred expressions don't give false positives. """
+    first, second, *last = (1, 2, 3, 4)
+    *last, = (1, 2)
+    return (first, second, last)