gh-94949: Disallow parsing parenthesised ctx mgr with old feature_version (#94950)

hauntsaninja · blurb-it[bot] · web-flow · commit 0daba822212c · 2022-07-18T22:10:49.000+01:00
* gh-94949: Disallow parsing parenthesised ctx manager with old feature_version * 📜🤖 Added by blurb_it. * Allow it with feature_version=(3, 9) as well Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
diff --git a/Grammar/python.gram b/Grammar/python.gram
@@ -391,7 +391,7 @@ for_stmt[stmt_ty]:
 with_stmt[stmt_ty]:
     | invalid_with_stmt_indent
     | 'with' '(' a[asdl_withitem_seq*]=','.with_item+ ','? ')' ':' b=block {
-        _PyAST_With(a, b, NULL, EXTRA) }
+        CHECK_VERSION(stmt_ty, 9, "Parenthesized context managers are", _PyAST_With(a, b, NULL, 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 {
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
@@ -738,6 +738,14 @@ def test_ast_asdl_signature(self):
         expressions[0] = f"expr = {ast.expr.__subclasses__()[0].__doc__}"
         self.assertCountEqual(ast.expr.__doc__.split("\n"), expressions)
 
+    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_issue40614_feature_version(self):
         ast.parse('f"{x=}"', feature_version=(3, 8))
         with self.assertRaises(SyntaxError):
diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-07-18-05-10-29.gh-issue-94949.OsZ7_s.rst b/Misc/NEWS.d/next/Core and Builtins/2022-07-18-05-10-29.gh-issue-94949.OsZ7_s.rst
@@ -0,0 +1 @@
+:func:`ast.parse` will no longer parse parenthesized context managers when passed ``feature_version`` less than ``(3, 9)``. Patch by Shantanu Jain.
diff --git a/Parser/parser.c b/Parser/parser.c

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+:func:`ast.parse` will no longer parse parenthesized context managers when passed ``feature_version`` less than ``(3, 9)``. Patch by Shantanu Jain.