The dir() listing omits the attributes "description" and "phrase":

>>> import http
>>> from pprint import pp
>>> r = http.HTTPStatus(404)
>>> pp(vars(r))
{'_value_': 404,
 'phrase': 'Not Found',
 'description': 'Nothing matches the given URI',
 '_name_': 'NOT_FOUND',
 '__objclass__': <enum 'HTTPStatus'>}
>>> r.value
404
>>> r.name
'NOT_FOUND'
>>> r.description
'Nothing matches the given URI'
>>> r.phrase
'Not Found'
>>> dir(r)
['__class__', '__doc__', '__module__', 'as_integer_ratio', 'bit_length', 'conjugate', 'denominator', 'from_bytes', 'imag', 'name', 'numerator', 'real', 'to_bytes', 'value']

One fix would be to teach IntEnum.__dir__() to include entries in the instance dict.  Another fix would be to provide a way for a IntEnum subclass to add to the known members list.

Adding to the existing dir() is as easy as writing one's own __dir__.

I think using the instance dict and omitting any keys with a leading underscore will do the right thing most of the time.

The fix should into `Enum` and not just `IntEnum` as other enumerations could also have extra attributes.

New changeset 68526fe258da8c01196fd7cf48e8e5f1280bf8fd by Angelin BOOZ in branch 'master':
bpo-40084: Enum - dir() includes member attributes (GH-19219)
https://github.com/python/cpython/commit/68526fe258da8c01196fd7cf48e8e5f1280bf8fd

New changeset f6d1520219899874d78e7710934c9b21af880f9a by Miss Islington (bot) in branch '3.8':
bpo-40084: [Enum] dir() includes member attributes (GH-19219) (GH-22853)
https://github.com/python/cpython/commit/f6d1520219899874d78e7710934c9b21af880f9a

New changeset 33cbb04986d0dabb9c542edc52bb4ea6106d3a81 by Miss Islington (bot) in branch '3.9':
bpo-40084: Enum - dir() includes member attributes (GH-19219)
https://github.com/python/cpython/commit/33cbb04986d0dabb9c542edc52bb4ea6106d3a81