bpo-45662: Fix the repr of InitVar with a type alias to the built-in class (GH-29291)

For example, InitVar[list[int]].

2 files changed, 5 insertions, 1 deletions

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 8643589..da06aa6 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -229,7 +229,7 @@ class InitVar:
         self.type = type
 
     def __repr__(self):
-        if isinstance(self.type, type):
+        if isinstance(self.type, type) and not isinstance(self.type, GenericAlias):
             type_name = self.type.__name__
         else:
             # typing objects, e.g. List[int]
diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index bcd004f..47075df 100644
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -1126,6 +1126,10 @@ class TestCase(unittest.TestCase):
         self.assertEqual(repr(InitVar[int]), 'dataclasses.InitVar[int]')
         self.assertEqual(repr(InitVar[List[int]]),
                          'dataclasses.InitVar[typing.List[int]]')
+        self.assertEqual(repr(InitVar[list[int]]),
+                         'dataclasses.InitVar[list[int]]')
+        self.assertEqual(repr(InitVar[int|str]),
+                         'dataclasses.InitVar[int | str]')
 
     def test_init_var_inheritance(self):
         # Note that this deliberately tests that a dataclass need not