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Recognize Hashable as a real protocol, refs #11799 #11802

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merged 2 commits into from
Mar 24, 2022
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Recognize Hashable as a real protocol, refs #11799 #11802

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582e24b
Recognize `Hashable` as a real protocol, refs #11799
sobolevn Dec 20, 2021
e1c8bfc
Merge branch 'master' into issue-11799
JelleZijlstra Mar 21, 2022
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4 changes: 4 additions & 0 deletions mypy/typeops.py
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Original file line number Diff line number Diff line change
Expand Up @@ -107,6 +107,10 @@ def class_callable(init_type: CallableType, info: TypeInfo, type_type: Instance,
explicit_type = init_ret_type if is_new else orig_self_type
if (
isinstance(explicit_type, (Instance, TupleType))
# We have to skip protocols, because it can can be a subtype of a return type
# by accident. Like `Hashable` is a subtype of `object`. See #11799
and isinstance(default_ret_type, Instance)
and not default_ret_type.type.is_protocol
# Only use the declared return type from __new__ or declared self in __init__
# if it is actually returning a subtype of what we would return otherwise.
and is_subtype(explicit_type, default_ret_type, ignore_type_params=True)
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13 changes: 13 additions & 0 deletions test-data/unit/pythoneval.test
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Expand Up @@ -1575,6 +1575,19 @@ reveal_type(x) # Revealed type is "collections.OrderedDict[builtins.str, builti
[out]
_testTypingExtensionsOrderedDictAlias.py:3: note: Revealed type is "collections.OrderedDict[builtins.str, builtins.str]"

[case testSpecialTypingProtocols]
# flags: --warn-unreachable
from typing import Awaitable, Hashable, Union, Tuple, List

obj: Union[Tuple[int], List[int]]
if isinstance(obj, Hashable):
reveal_type(obj)
if isinstance(obj, Awaitable):
reveal_type(obj)
[out]
_testSpecialTypingProtocols.py:6: note: Revealed type is "Tuple[builtins.int]"
_testSpecialTypingProtocols.py:8: error: Statement is unreachable

[case testEnumValueWithPlaceholderNodeType]
# https://github.com/python/mypy/issues/11971
from enum import Enum
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