Closed
Description
Bug report
Bug description:
In typing._eval_type, generic aliases are reconstructed this way:
Lines 488 to 489 in e53d105
As GenericAlias is subclassable, we can loose the actual subclass in some cases:
from typing import get_type_hints from collections.abc import Callable C = Callable[[str, 'int'], int] C.__class__ #> <class 'collections.abc._CallableGenericAlias'> C.__class__.__bases__ #> (<class 'types.GenericAlias'>,) class A: c: C hints = get_type_hints(A) hints['c'].__class__ #> <class 'types.GenericAlias'>I couldn't find a way to get actual bugs from it, but the repr is different:
hints['c'] #> collections.abc.Callable[str, int, int] C #> collections.abc.Callable[[str, 'int'], int]The issue is also relevant for typing._strip_annotations().
Proposed fix
diff --git a/Lib/typing.py b/Lib/typing.py index 4b3c63b25ae..25e0576839f 100644 --- a/Lib/typing.py +++ b/Lib/typing.py @@ -486,7 +486,9 @@ def _eval_type(t, globalns, localns, type_params=_sentinel, *, recursive_guard=f if ev_args == t.__args__: return t if isinstance(t, GenericAlias): - return GenericAlias(t.__origin__, ev_args) + if _should_unflatten_callable_args(t, ev_args): + return t.__class__(t.__origin__, (ev_args[:-1], ev_args[-1])) + return t.__class__(t.__origin__, ev_args) if isinstance(t, Union): return functools.reduce(operator.or_, ev_args) else:CPython versions tested on:
3.13
Operating systems tested on:
Linux