bpo-40334: Add support for feature_version in new PEG parser (GH-19827)

`ast.parse` and `compile` support a `feature_version` parameter that
tells the parser to parse the input string, as if it were written in
an older Python version.
The `feature_version` is propagated to the tokenizer, which uses it
to handle the three different stages of support for `async` and
`await`. Additionally, it disallows the following at parser level:
- The '@' operator in < 3.5
- Async functions in < 3.5
- Async comprehensions in < 3.6
- Underscores in numeric literals in < 3.6
- Await expression in < 3.5
- Variable annotations in < 3.6
- Async for-loops in < 3.5
- Async with-statements in < 3.5
- F-strings in < 3.6

Closes we-like-parsers/cpython#124.

1 files changed, 0 insertions, 6 deletions

diff --git a/Lib/test/test_type_comments.py b/Lib/test/test_type_comments.py
index 6c3f6ed..6027b3b 100644
--- a/Lib/test/test_type_comments.py
+++ b/Lib/test/test_type_comments.py
@@ -252,7 +252,6 @@ class TypeCommentTests(unittest.TestCase):
         self.assertEqual(tree.body[0].type_comment, None)
         self.assertEqual(tree.body[1].type_comment, None)
 
-    @support.skip_if_new_parser("Pegen does not support feature_version yet")
     def test_asyncdef(self):
         for tree in self.parse_all(asyncdef, minver=5):
             self.assertEqual(tree.body[0].type_comment, "() -> int")
@@ -261,27 +260,22 @@ class TypeCommentTests(unittest.TestCase):
         self.assertEqual(tree.body[0].type_comment, None)
         self.assertEqual(tree.body[1].type_comment, None)
 
-    @support.skip_if_new_parser("Pegen does not support feature_version yet")
     def test_asyncvar(self):
         for tree in self.parse_all(asyncvar, maxver=6):
             pass
 
-    @support.skip_if_new_parser("Pegen does not support feature_version yet")
     def test_asynccomp(self):
         for tree in self.parse_all(asynccomp, minver=6):
             pass
 
-    @support.skip_if_new_parser("Pegen does not support feature_version yet")
     def test_matmul(self):
         for tree in self.parse_all(matmul, minver=5):
             pass
 
-    @support.skip_if_new_parser("Pegen does not support feature_version yet")
     def test_fstring(self):
         for tree in self.parse_all(fstring, minver=6):
             pass
 
-    @support.skip_if_new_parser("Pegen does not support feature_version yet")
     def test_underscorednumber(self):
         for tree in self.parse_all(underscorednumber, minver=6):
             pass