From 9b7f5c6be6c9880f0f95e49722cbbe7f9e5d1e51 Mon Sep 17 00:00:00 2001
From: "Youtong0826.w" <91408029+Youtong0826@users.noreply.github.com>
Date: Fri, 14 Oct 2022 10:27:47 +0800
Subject: [PATCH] Fix errors that will occur in python3.11 (#1680)

Apply correct fix for MISSING default

Co-authored-by: BobDotCom <71356958+BobDotCom@users.noreply.github.com>
---
 discord/ext/commands/flags.py | 14 +++++++-------
 discord/utils.py              |  6 ++++++
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/discord/ext/commands/flags.py b/discord/ext/commands/flags.py
index 82183fb368..ffc80fb254 100644
--- a/discord/ext/commands/flags.py
+++ b/discord/ext/commands/flags.py
@@ -31,7 +31,7 @@
 from dataclasses import dataclass, field
 from typing import TYPE_CHECKING, Any, Iterator, Literal, Pattern, TypeVar, Union
 
-from discord.utils import MISSING, maybe_coroutine, resolve_annotation
+from discord.utils import MISSING, MissingField, maybe_coroutine, resolve_annotation
 
 from .converter import run_converters
 from .errors import (
@@ -81,13 +81,13 @@ class Flag:
         Whether multiple given values overrides the previous value.
     """
 
-    name: str = MISSING
+    name: str = MissingField
     aliases: list[str] = field(default_factory=list)
-    attribute: str = MISSING
-    annotation: Any = MISSING
-    default: Any = MISSING
-    max_args: int = MISSING
-    override: bool = MISSING
+    attribute: str = MissingField
+    annotation: Any = MissingField
+    default: Any = MissingField
+    max_args: int = MissingField
+    override: bool = MissingField
     cast_to_dict: bool = False
 
     @property
diff --git a/discord/utils.py b/discord/utils.py
index 9f1cb4f801..6cefb3531b 100644
--- a/discord/utils.py
+++ b/discord/utils.py
@@ -38,6 +38,7 @@
 import warnings
 from base64 import b64encode
 from bisect import bisect_left
+from dataclasses import field
 from inspect import isawaitable as _isawaitable
 from inspect import signature as _signature
 from operator import attrgetter
@@ -114,6 +115,11 @@ def __repr__(self) -> str:
 
 
 MISSING: Any = _MissingSentinel()
+# As of 3.11, directly setting a dataclass field to MISSING causes a ValueError. Using
+# field(default=MISSING) produces the same error, but passing a lambda to
+# default_factory produces the same behavior as default=MISSING and does not raise an
+# error.
+MissingField = field(default_factory=lambda: MISSING)
 
 
 class _cached_property: