gh-95066: ast: Replace assert with ValueError (GH-95072)

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

2 files changed, 8 insertions, 1 deletions

diff --git a/Lib/ast.py b/Lib/ast.py
index 4e2ae85..ebf4529 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -42,7 +42,8 @@ def parse(source, filename='<unknown>', mode='exec', *,
         flags |= PyCF_TYPE_COMMENTS
     if isinstance(feature_version, tuple):
         major, minor = feature_version  # Should be a 2-tuple.
-        assert major == 3
+        if major != 3:
+            raise ValueError(f"Unsupported major version: {major}")
         feature_version = minor
     elif feature_version is None:
         feature_version = -1
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index 9734218..de34ccf 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -756,6 +756,12 @@ class AST_Tests(unittest.TestCase):
         with self.assertRaises(SyntaxError):
             ast.parse('(x := 0)', feature_version=(3, 7))
 
+    def test_invalid_major_feature_version(self):
+        with self.assertRaises(ValueError):
+            ast.parse('pass', feature_version=(2, 7))
+        with self.assertRaises(ValueError):
+            ast.parse('pass', feature_version=(4, 0))
+
     def test_constant_as_name(self):
         for constant in "True", "False", "None":
             expr = ast.Expression(ast.Name(constant, ast.Load()))