HTTPException pickle fails when constructed using named parameter status_code

[nexusdk]

from starlette.exceptions import HTTPException
import pickle
# Works:
pickle.loads(pickle.dumps(HTTPException(404)))
# Breaks:
pickle.loads(pickle.dumps(HTTPException(status_code=404)))

The following error gets thrown:

TypeError: __init__() missing 1 required positional argument: 'status_code'

Tested on Python versions 3.7.12 and 3.9.10
Starlette version 0.20.1

[nexusdk]

This seems related:
https://stackoverflow.com/questions/49715881/how-to-pickle-inherited-exceptions
Adding this to the HTTPException class seems to fix the problem:

    def __reduce__(self) -> tuple[typing.Any, ...]:
        return type(self), (self.status_code, self.detail, self.headers)

[nexusdk]

#1670

[Kludex]

This works if you use the copyreg module.

import copyreg
import pickle
from starlette.exceptions import HTTPException

def pickle_http_exception(exc):
    return HTTPException, (exc.status_code, exc.detail, exc.headers)

copyreg.pickle(HTTPException, pickle_http_exception)
print(pickle.loads(pickle.dumps(HTTPException(status_code=404))))