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functools.lru_cache wrapped function with TypeVar has wrong return type. #6987
Description
Hi,
I think there is a problem when using functools.lru_cache (and functools.cache). When the decorated function uses a TypeVar for typing arguments and return type, the wrapped function returend by functools.lru_cache has wrong (or unresolved) types.
This is not the case when replacing the TypeVar with an explicit type. See the mwe below. Thx.
import functools
from typing import TypeVar
_T = TypeVar("_T")
def my_func(elem: _T) -> list[_T]:
return [elem]
my_func_cached = functools.lru_cache(my_func)
a = my_func("a")
reveal_type(a) # Revealed type is "builtins.list[builtins.str*]"
a_c = my_func_cached("a")
# ERROR: this should be "builtins.list*[builtins.str]"
reveal_type(a_c) # Revealed type is "builtins.list*[_T`-1]"
# this works
def my_func_str(elem: str) -> list[str]:
return [elem]
my_func_str_cached = functools.lru_cache(my_func_str)
a_str = my_func_str("a")
reveal_type(a_str) # Revealed type is "builtins.list[builtins.str]"
a_str_c = my_func_str_cached("a")
reveal_type(a_str_c) # Revealed type is "builtins.list*[builtins.str]"Running:
Python 3.10.1
mypy 0.931
Linux 5.16.0-arch1-1
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