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Description
Bug Report
Mypy succeeds evaluating an attr converter that is an (Any) -> Any function, but fails to evaluate a converter that is returned by a higher-order function that returns an (Any) -> Any function.
To Reproduce
This works as expected:
from attr import define, field
def truncate(val):
return val[:40]
@define
class Person:
first_name: str = field(converter=truncate)
last_name: str = field(converter=truncate)
reveal_type(truncate)Output:
scratch.py:14: note: Revealed type is "def (val: Any) -> Any"
Success: no issues found in 1 source file
But this does not:
from collections.abc import Callable
from typing import Any
from attr import define, field
def truncate(length) -> Callable[[Any], Any]:
def truncate_converter(val):
return val[:length]
return truncate_converter
@define
class Person:
first_name: str = field(converter=truncate(40))
last_name: str = field(converter=truncate(80))
reveal_type(truncate(40))
reveal_type(truncate(80))Expected Behavior
Output:
scratch.py:20: note: Revealed type is "def (Any) -> Any"
scratch.py:21: note: Revealed type is "def (Any) -> Any"
Success: no issues found in 1 source file
Actual Behavior
Output:
scratch.py:16: error: Unsupported converter, only named functions, types and lambdas are currently supported [misc]
scratch.py:17: error: Unsupported converter, only named functions, types and lambdas are currently supported [misc]
scratch.py:20: note: Revealed type is "def (Any) -> Any"
scratch.py:21: note: Revealed type is "def (Any) -> Any"
Found 2 errors in 1 file (checked 1 source file)
Your Environment
- Mypy version used: 1.4.1
- Mypy command-line flags: just the file name, no extra flags.
- Mypy configuration options from
mypy.ini(and other config files):[tool.mypy] platform = "linux" python_version = "3.10"
- Python version used: 3.10.12