Parenthesized single starred expression (*x) is no longer valid anywhere in Python 3.9+

parso/python/errors.py

@@ -753,6 +753,16 @@ class _StarExprRule(SyntaxRule):
                     return False
             return False
 
+        if self._normalizer.version >= (3, 9):
+            ancestor = node.parent
+        else:
+            ancestor = _skip_parens_bottom_up(node)
+        # starred expression not in tuple/list/set
+        if ancestor.type not in (*_STAR_EXPR_PARENTS, 'dictorsetmaker') \
+                and not (ancestor.type == 'atom' and ancestor.children[0] != '('):
+            self.add_issue(node, message="can't use starred expression here")
+            return
+
         if check_delete_starred(node):
             if self._normalizer.version >= (3, 9):
                 self.add_issue(node, message="cannot delete starred")
@@ -764,12 +774,6 @@ class _StarExprRule(SyntaxRule):
             # [*[] for a in [1]]
             if node.parent.children[1].type in _COMP_FOR_TYPES:
                 self.add_issue(node, message=self.message_iterable_unpacking)
-                return
-
-        ancestor = _skip_parens_bottom_up(node)
-        # starred expression not in tuple/list/set
-        if ancestor.type not in (*_STAR_EXPR_PARENTS, 'dictorsetmaker', 'atom'):
-            self.add_issue(node, message="can't use starred expression here")
 
 
 @ErrorFinder.register_rule(types=_STAR_EXPR_PARENTS)
@@ -1107,7 +1111,10 @@ class _CheckAssignmentRule(SyntaxRule):
                 else:
                     self.add_issue(node, message="can't use starred expression here")
             else:
-                ancestor = _skip_parens_bottom_up(node)
+                if self._normalizer.version >= (3, 9):
+                    ancestor = node.parent
+                else:
+                    ancestor = _skip_parens_bottom_up(node)
                 if ancestor.type not in _STAR_EXPR_PARENTS and not is_aug_assign \
                         and not (ancestor.type == 'atom' and ancestor.children[0] == '['):
                     message = "starred assignment target must be in a list or tuple"

test/test_python_errors.py

@@ -425,10 +425,6 @@ def test_unparenthesized_genexp(source, no_errors):
         ('a, *b = 1', True),
         ('a, *b, c', True),
         ('a, *b, c = 1', True),
-        ('a, (*b), c', True),
-        ('a, (*b), c = 1', True),
-        ('a, ((*b)), c', True),
-        ('a, ((*b)), c = 1', True),
         ('a, (*b, c), d', True),
         ('a, (*b, c), d = 1', True),
         ('*a.b,', True),
@@ -455,6 +451,19 @@ def test_starred_expr(source, no_errors):
     assert bool(_get_error_list(source, version="3")) ^ no_errors
 
 
+@pytest.mark.parametrize(
+    'code', [
+        'a, (*b), c',
+        'a, (*b), c = 1',
+        'a, ((*b)), c',
+        'a, ((*b)), c = 1',
+    ]
+)
+def test_parenthesized_single_starred_expr(code):
+    assert not _get_error_list(code, version='3.8')
+    assert _get_error_list(code, version='3.9')
+
+
 @pytest.mark.parametrize(
     'code', [
         '() = ()',