Drop the requirement that lhs and rhs should have the same number of elements when inferring Starred

This improves the capabilities a bit, since we know infer those as empty lists

3 files changed, 38 insertions, 11 deletions

diff --git a/astroid/protocols.py b/astroid/protocols.py
index 64904524..9ebeb92a 100644
--- a/astroid/protocols.py
+++ b/astroid/protocols.py
@@ -586,18 +586,15 @@ def starred_assigned_stmts(self, node=None, context=None, asspath=None):
         except exceptions.InferenceError:
             yield util.Uninferable
             return
-        if rhs is util.Uninferable or not hasattr(rhs, 'elts'):
-            # Not interested in inferred values without elts.
+        if rhs is util.Uninferable or not hasattr(rhs, 'itered'):
             yield util.Uninferable
             return
 
-        elts = collections.deque(rhs.elts[:])
-        if len(lhs.elts) > len(rhs.elts):
-            raise exceptions.InferenceError('More targets, {targets!r}, than '
-                                            'values to unpack, {values!r}.',
-                                            node=self, targets=lhs,
-                                            values=rhs, unknown=node,
-                                            context=context)
+        try:
+            elts = collections.deque(rhs.itered())
+        except TypeError:
+            yield util.Uninferable
+            return
 
         # Unpack iteratively the values from the rhs of the assignment,
         # until the find the starred node. What will remain will
@@ -608,11 +605,15 @@ def starred_assigned_stmts(self, node=None, context=None, asspath=None):
 
         for index, left_node in enumerate(lhs.elts):
             if not isinstance(left_node, nodes.Starred):
+                if not elts:
+                    break
                 elts.popleft()
                 continue
             lhs_elts = collections.deque(reversed(lhs.elts[index:]))
             for right_node in lhs_elts:
                 if not isinstance(right_node, nodes.Starred):
+                    if not elts:
+                        break
                     elts.pop()
                     continue
                 # We're done
diff --git a/astroid/tests/unittest_inference.py b/astroid/tests/unittest_inference.py
index 9b7c51cf..5c3800d3 100644
--- a/astroid/tests/unittest_inference.py
+++ b/astroid/tests/unittest_inference.py
@@ -4516,5 +4516,33 @@ def test_slice_inference_in_for_loops_not_working():
         assert inferred == util.Uninferable
 
 
+def test_unpacking_starred_and_dicts_in_assignment():
+    node = extract_node('''
+    a, *b = {1:2, 2:3, 3:4}
+    b
+    ''')
+    inferred = next(node.infer())
+    assert isinstance(inferred, nodes.List)
+    assert inferred.as_string() == '[2, 3]'
+
+    node = extract_node('''
+    a, *b = {1:2}
+    b
+    ''')
+    inferred = next(node.infer())
+    assert isinstance(inferred, nodes.List)
+    assert inferred.as_string() == '[]'
+
+
+def test_unpacking_starred_empty_list_in_assignment():
+    node = extract_node('''
+    a, *b, c = [1, 2]
+    b #@
+    ''')
+    inferred = next(node.infer())
+    assert isinstance(inferred, nodes.List)
+    assert inferred.as_string() == '[]'
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/astroid/tests/unittest_protocols.py b/astroid/tests/unittest_protocols.py
index 6d12a001..c2619413 100644
--- a/astroid/tests/unittest_protocols.py
+++ b/astroid/tests/unittest_protocols.py
@@ -124,8 +124,6 @@ class ProtocolTests(unittest.TestCase):
     def test_assign_stmts_starred_fails(self):
         # Too many starred
         self._helper_starred_inference_error("a, *b, *c = (1, 2, 3) #@")
-        # Too many lhs values
-        self._helper_starred_inference_error("a, *b, c = (1, 2) #@")
         # This could be solved properly, but it complicates needlessly the
         # code for assigned_stmts, without offering real benefit.
         self._helper_starred_inference_error(