pythongh-115881: Ensure ast.parse() parses conditional context managers even with low feature_version passed (python#115920)

Author: AlexWaygood

Grammar/python.gram

@@ -393,7 +393,7 @@ for_stmt[stmt_ty]:
 with_stmt[stmt_ty]:
     | invalid_with_stmt_indent
     | 'with' '(' a[asdl_withitem_seq*]=','.with_item+ ','? ')' ':' tc=[TYPE_COMMENT] b=block {
-       CHECK_VERSION(stmt_ty, 9, "Parenthesized context managers are", _PyAST_With(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA)) }
+       _PyAST_With(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA) }
     | 'with' a[asdl_withitem_seq*]=','.with_item+ ':' tc=[TYPE_COMMENT] b=block {
         _PyAST_With(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA) }
     | 'async' 'with' '(' a[asdl_withitem_seq*]=','.with_item+ ','? ')' ':' b=block {

Lib/test/test_ast.py

@@ -1045,19 +1045,15 @@ def test_positional_only_feature_version(self):
         with self.assertRaises(SyntaxError):
             ast.parse('lambda x=1, /: ...', feature_version=(3, 7))
 
-    def test_parenthesized_with_feature_version(self):
-        ast.parse('with (CtxManager() as example): ...', feature_version=(3, 10))
-        # While advertised as a feature in Python 3.10, this was allowed starting 3.9
-        ast.parse('with (CtxManager() as example): ...', feature_version=(3, 9))
-        with self.assertRaises(SyntaxError):
-            ast.parse('with (CtxManager() as example): ...', feature_version=(3, 8))
-        ast.parse('with CtxManager() as example: ...', feature_version=(3, 8))
-
     def test_assignment_expression_feature_version(self):
         ast.parse('(x := 0)', feature_version=(3, 8))
         with self.assertRaises(SyntaxError):
             ast.parse('(x := 0)', feature_version=(3, 7))
 
+    def test_conditional_context_managers_parse_with_low_feature_version(self):
+        # regression test for gh-115881
+        ast.parse('with (x() if y else z()): ...', feature_version=(3, 8))
+
     def test_exception_groups_feature_version(self):
         code = dedent('''
         try: ...

Lib/test/test_type_comments.py

@@ -309,7 +309,7 @@ def test_withstmt(self):
         self.assertEqual(tree.body[0].type_comment, None)
 
     def test_parenthesized_withstmt(self):
-        for tree in self.parse_all(parenthesized_withstmt, minver=9):
+        for tree in self.parse_all(parenthesized_withstmt):
             self.assertEqual(tree.body[0].type_comment, "int")
             self.assertEqual(tree.body[1].type_comment, "int")
         tree = self.classic_parse(parenthesized_withstmt)

Misc/NEWS.d/next/Library/2024-02-25-19-20-05.gh-issue-115881.ro_Kuw.rst

@@ -0,0 +1,4 @@
+Fix issue where :func:`ast.parse` would incorrectly flag conditional context
+managers (such as ``with (x() if y else z()): ...``) as invalid syntax if
+``feature_version=(3, 8)`` was passed. This reverts changes to the
+grammar made as part of gh-94949.