pythongh-133194: Add CHECK_VERSION to new PEP758 grammar (python#133195)

Author: sobolevn

Grammar/python.gram

@@ -442,15 +442,23 @@ try_stmt[stmt_ty]:
 except_block[excepthandler_ty]:
     | invalid_except_stmt_indent
     | 'except' e=expressions ':' b=block {
-        _PyAST_ExceptHandler(e,  NULL, b, EXTRA) }
+        CHECK_VERSION(
+            excepthandler_ty, 
+            14, 
+            "except expressions without parentheses", 
+            _PyAST_ExceptHandler(e,  NULL, b, EXTRA)) }
     | 'except' e=expression 'as' t=NAME  ':' b=block {
         _PyAST_ExceptHandler(e, ((expr_ty) t)->v.Name.id, b, EXTRA) }
     | 'except' ':' b=block { _PyAST_ExceptHandler(NULL, NULL, b, EXTRA) }
     | invalid_except_stmt
 except_star_block[excepthandler_ty]:
     | invalid_except_star_stmt_indent
     | 'except' '*' e=expressions ':' b=block {
-        _PyAST_ExceptHandler(e, NULL, b, EXTRA) }
+        CHECK_VERSION(
+            excepthandler_ty, 
+            14, 
+            "except expressions without parentheses", 
+            _PyAST_ExceptHandler(e,  NULL, b, EXTRA)) }
     | 'except' '*' e=expression 'as' t=NAME ':' b=block {
         _PyAST_ExceptHandler(e, ((expr_ty) t)->v.Name.id, b, EXTRA) }
     | invalid_except_star_stmt

Lib/test/test_ast/test_ast.py

@@ -675,6 +675,28 @@ def test_assignment_expression_feature_version(self):
         with self.assertRaises(SyntaxError):
             ast.parse('(x := 0)', feature_version=(3, 7))
 
+    def test_pep758_except_without_parens(self):
+        code = textwrap.dedent("""
+            try:
+                ...
+            except ValueError, TypeError:
+                ...
+        """)
+        ast.parse(code, feature_version=(3, 14))
+        with self.assertRaises(SyntaxError):
+            ast.parse(code, feature_version=(3, 13))
+
+    def test_pep758_except_star_without_parens(self):
+        code = textwrap.dedent("""
+            try:
+                ...
+            except* ValueError, TypeError:
+                ...
+        """)
+        ast.parse(code, feature_version=(3, 14))
+        with self.assertRaises(SyntaxError):
+            ast.parse(code, feature_version=(3, 13))
+
     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))

Misc/NEWS.d/next/Core_and_Builtins/2025-04-30-13-09-20.gh-issue-133194.25_G5c.rst

@@ -0,0 +1,2 @@
+:func:`ast.parse` will no longer parse new :pep:`758` syntax with older
+*feature_version* passed.