fix: Apply mypy 0.920 update (#104)

* setup: Upgrade mypy to 0.920
* fix: Remove bogus type-casting
* fix: Call `__init__()` as a classmethod

changes/104.fix

@@ -0,0 +1 @@
+Fix minor typing errors discovered by mypy 0.920 update

setup.cfg

@@ -83,7 +83,7 @@ lint =
     flake8>=4.0.1
     flake8-commas>=2.1
 typecheck =
-    mypy>=0.910
+    mypy>=0.920
     types-python-dateutil
     types-toml
     types-setuptools

src/ai/backend/common/cli.py

@@ -4,7 +4,7 @@
 from importlib import import_module
 import re
 from types import FunctionType
-from typing import Any, Optional, Union, Type, cast
+from typing import Any, Optional, Union, Type
 
 import click
 
@@ -58,7 +58,7 @@ class EnumChoice(click.Choice):
     enum: Type[Enum]
 
     def __init__(self, enum: Type[Enum]):
-        super().__init__([*cast(Enum, enum)._member_map_.keys()])
+        super().__init__([*enum._member_map_.keys()])
         self.enum = enum
 
     def convert(self, value: Any, param, ctx):

src/ai/backend/common/types.py

@@ -99,7 +99,7 @@ async def new(cls: Type[T_aobj], *args, **kwargs) -> T_aobj:
         This is a copy of ``__new__()`` to workaround it.
         '''
         instance = super().__new__(cls)
-        instance.__init__(*args, **kwargs)
+        cls.__init__(instance, *args, **kwargs)
         await instance.__ainit__()
         return instance