Fix a crash involving two starred expressions inside a call (#1535)

Author: jacobtylerwalls

ChangeLog

@@ -23,6 +23,11 @@ Release date: TBA
 
 * Fix ``col_offset`` attribute for nodes involving ``with`` on ``PyPy``.
 
+* Fixed a crash involving two starred expressions: one inside a comprehension,
+  both inside a call.
+
+  Refs PyCQA/pylint#6372
+
 * Made ``FunctionDef.implicit_parameters`` return 1 for methods by making
   ``FunctionDef.is_bound`` return ``True``, as it does for class methods.
 

astroid/protocols.py

@@ -690,6 +690,9 @@ def _determine_starred_iteration_lookups(starred, target, lookups):
     if isinstance(stmt, nodes.Assign):
         value = stmt.value
         lhs = stmt.targets[0]
+        if not isinstance(lhs, nodes.BaseContainer):
+            yield util.Uninferable
+            return
 
         if sum(1 for _ in lhs.nodes_of_class(nodes.Starred)) > 1:
             raise InferenceError(

tests/unittest_protocols.py

@@ -125,6 +125,17 @@ def test(arg):
             "a, (*b, c), d = (1, (2, 3, 4), 5) #@", Uninferable
         )
 
+    def test_assigned_stmts_starred_inside_call(self) -> None:
+        """Regression test for https://github.com/PyCQA/pylint/issues/6372"""
+        code = "string_twos = ''.join(str(*y) for _, *y in [[1, 2], [1, 2]]) #@"
+        stmt = extract_node(code)
+        starred = next(stmt.nodes_of_class(nodes.Starred))
+        starred_stmts = starred.assigned_stmts()
+        self.assertIs(next(starred_stmts), Uninferable)
+        # Generator exhausted after one call
+        with self.assertRaises(StopIteration):
+            next(starred_stmts)
+
     def test_assign_stmts_starred_fails(self) -> None:
         # Too many starred
         self._helper_starred_inference_error("a, *b, *c = (1, 2, 3) #@")