diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py index 3b8efe16c6e238..40f0be887bef72 100644 --- a/Lib/test/test_typing.py +++ b/Lib/test/test_typing.py @@ -186,6 +186,16 @@ def test_union_unique(self): self.assertEqual(Union[X, int].__parameters__, (X,)) self.assertIs(Union[X, int].__origin__, Union) + def test_or(self): + X = TypeVar('X') + # use a string because str doesn't implement + # __or__/__ror__ itself + self.assertEqual(X | "x", Union[X, "x"]) + self.assertEqual("x" | X, Union["x", X]) + # make sure the order is correct + self.assertEqual(get_args(X | "x"), (X, ForwardRef("x"))) + self.assertEqual(get_args("x" | X), (ForwardRef("x"), X)) + def test_union_constrained(self): A = TypeVar('A', str, bytes) self.assertNotEqual(Union[A, str], Union[A]) diff --git a/Lib/typing.py b/Lib/typing.py index 6224930c3b0275..9091cf62ed045a 100644 --- a/Lib/typing.py +++ b/Lib/typing.py @@ -646,8 +646,8 @@ def __init__(self, bound, covariant, contravariant): def __or__(self, right): return Union[self, right] - def __ror__(self, right): - return Union[self, right] + def __ror__(self, left): + return Union[left, self] def __repr__(self): if self.__covariant__: diff --git a/Misc/NEWS.d/next/Library/2021-04-10-19-14-49.bpo-43772.Bxq0zQ.rst b/Misc/NEWS.d/next/Library/2021-04-10-19-14-49.bpo-43772.Bxq0zQ.rst new file mode 100644 index 00000000000000..648357b3faa741 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2021-04-10-19-14-49.bpo-43772.Bxq0zQ.rst @@ -0,0 +1 @@ +Fixed the return value of ``TypeVar.__ror__``. Patch by Jelle Zijlstra.