The union type accepts any function from the typing module:

>>> import typing
>>> int | typing.cast
int | typing.cast
>>> int | typing.get_type_hints
int | typing.get_type_hints

It is a consequence of too lenient check for the typing.NewType() result (which does not work at all with PR 9951).

Is it worth being picky about this? The internal data structures are safe. A static checker will complain. What more do you need?

It is only reminder that our test for NewType is arbitrary. And it is not compatible with PR 9951. Possible solutions are:

1. Make NewType a class and add more strict test. Pro -- we can make arbitrary repr, contra -- it has small negative effect on performance. See issue34963.

2. Remove the test for NewType at all and allow or-ing types and arbitrary functions.

3. Introduce a special attribute to distinguish unionable objects. It will make the code of unionobject.c simpler.

I lean towards option 1 (not excluding 3). Small performance losses seem inevitable.

@Serhiy
> 1. Make NewType a class and add more strict test.

See also: issue44353 (https://bugs.python.org/issue44353). We had some discussion there about converting to class but it ended in a deadlock.

I think making NewType into a class isn't a good idea, it would be too slow. But I like issue34963 (PR 9951).

So then let's do some variation on (3) -- unionable things would include all types (of course), typevars, and things that have a special attribute. We could then set that special attribute on the function returned by NewType (like PR 9951 already does for __name__ and __qualname__).

What to call it? Maybe "__unionable__"?

It does not happen anymore on `main` (3.11):

```
Python 3.11.0a4+ (heads/main-dirty:ef3ef6fa43, Jan 20 2022, 20:48:25) [Clang 11.0.0 (clang-1100.0.33.16)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import typing

>>> int | typing.cast
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for |: 'type' and 'function'

>>> int | typing.get_type_hints
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for |: 'type' and 'function' 
```

Do you recommend to just close this as "fixed"?

Looks like it was fixed indeed, `NewType` is now a class. And I cannot reproduce it even on `3.10`:

```
Python 3.10.0 (default, Nov  1 2021, 10:24:06) [Clang 11.0.0 (clang-1100.0.33.16)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import typing

>>> int | typing.cast
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for |: 'type' and 'function'

>>> int | typing.get_type_hints
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for |: 'type' and 'function'
```