Fix type-errors in commands extension

discord/client.py

@@ -78,7 +78,8 @@ from .sticker import GuildSticker, StandardSticker, StickerPack, _sticker_factor
 
 if TYPE_CHECKING:
     from .types.guild import Guild as GuildPayload
-    from .abc import SnowflakeTime, PrivateChannel, GuildChannel, Snowflake
+    from .abc import SnowflakeTime, Snowflake, PrivateChannel
+    from .guild import GuildChannel
     from .channel import DMChannel
     from .message import Message
     from .member import Member

discord/ext/commands/bot.py

@@ -33,7 +33,7 @@ import importlib.util
 import sys
 import traceback
 import types
-from typing import Any, Callable, Mapping, List, Dict, TYPE_CHECKING, Optional, TypeVar, Type, Union
+from typing import Any, Callable, Mapping, List, Dict, TYPE_CHECKING, Optional, TypeVar, Type, Union, overload
 
 import discord
 
@@ -65,6 +65,7 @@ MISSING: Any = discord.utils.MISSING
 T = TypeVar('T')
 CFT = TypeVar('CFT', bound='CoroFunc')
 CXT = TypeVar('CXT', bound='Context')
+BT = TypeVar('BT', bound='Union[Bot, AutoShardedBot]')
 
 
 def when_mentioned(bot: Union[Bot, AutoShardedBot], msg: Message) -> List[str]:
@@ -932,7 +933,15 @@ class BotBase(GroupMixin):
 
         return ret
 
-    async def get_context(self, message: Message, *, cls: Type[CXT] = Context) -> CXT:
+    @overload
+    async def get_context(self: BT, message: Message) -> Context[BT]:
+        ...
+
+    @overload
+    async def get_context(self, message: Message, *, cls: Type[CXT] = ...) -> CXT:
+        ...
+
+    async def get_context(self, message: Message, *, cls: Type[Context] = Context) -> Any:
         r"""|coro|
 
         Returns the invocation context from the message.

discord/ext/commands/converter.py

@@ -41,6 +41,7 @@ from typing import (
     Tuple,
     Union,
     runtime_checkable,
+    overload,
 )
 
 import discord
@@ -48,7 +49,8 @@ from .errors import *
 
 if TYPE_CHECKING:
     from .context import Context
-    from discord.message import PartialMessageableChannel
+    from discord.state import Channel
+    from discord.threads import Thread
     from .bot import Bot, AutoShardedBot
 
     _Bot = Union[Bot, AutoShardedBot]
@@ -357,7 +359,7 @@ class PartialMessageConverter(Converter[discord.PartialMessage]):
     @staticmethod
     def _resolve_channel(
         ctx: Context[_Bot], guild_id: Optional[int], channel_id: Optional[int]
-    ) -> Optional[PartialMessageableChannel]:
+    ) -> Optional[Union[Channel, Thread]]:
         if channel_id is None:
             # we were passed just a message id so we can assume the channel is the current context channel
             return ctx.channel
@@ -373,8 +375,8 @@ class PartialMessageConverter(Converter[discord.PartialMessage]):
     async def convert(self, ctx: Context[_Bot], argument: str) -> discord.PartialMessage:
         guild_id, message_id, channel_id = self._get_id_matches(ctx, argument)
         channel = self._resolve_channel(ctx, guild_id, channel_id)
-        if not channel:
-            raise ChannelNotFound(channel_id)
+        if not channel or not isinstance(channel, discord.abc.Messageable):
+            raise ChannelNotFound(channel_id)  # type: ignore - channel_id won't be None here
         return discord.PartialMessage(channel=channel, id=message_id)
 
 
@@ -399,14 +401,14 @@ class MessageConverter(IDConverter[discord.Message]):
         if message:
             return message
         channel = PartialMessageConverter._resolve_channel(ctx, guild_id, channel_id)
-        if not channel:
-            raise ChannelNotFound(channel_id)
+        if not channel or not isinstance(channel, discord.abc.Messageable):
+            raise ChannelNotFound(channel_id)  # type: ignore - channel_id won't be None here
         try:
             return await channel.fetch_message(message_id)
         except discord.NotFound:
             raise MessageNotFound(argument)
         except discord.Forbidden:
-            raise ChannelNotReadable(channel)
+            raise ChannelNotReadable(channel)  # type: ignore - type-checker thinks channel could be a DMChannel at this point
 
 
 class GuildChannelConverter(IDConverter[discord.abc.GuildChannel]):
@@ -449,7 +451,8 @@ class GuildChannelConverter(IDConverter[discord.abc.GuildChannel]):
         else:
             channel_id = int(match.group(1))
             if guild:
-                result = guild.get_channel(channel_id)
+                # guild.get_channel returns an explicit union instead of the base class
+                result = guild.get_channel(channel_id)  # type: ignore
             else:
                 result = _get_from_guilds(bot, 'get_channel', channel_id)
 

discord/ext/commands/core.py

@@ -99,7 +99,7 @@ __all__ = (
 MISSING: Any = discord.utils.MISSING
 
 T = TypeVar('T')
-CogT = TypeVar('CogT', bound='Cog')
+CogT = TypeVar('CogT', bound='Optional[Cog]')
 CommandT = TypeVar('CommandT', bound='Command')
 ContextT = TypeVar('ContextT', bound='Context')
 # CHT = TypeVar('CHT', bound='Check')
@@ -307,7 +307,7 @@ class Command(_BaseCommand, Generic[CogT, P, T]):
             Callable[Concatenate[ContextT, P], Coro[T]],
         ],
         **kwargs: Any,
-    ):
+    ) -> None:
         if not asyncio.iscoroutinefunction(func):
             raise TypeError('Callback must be a coroutine.')
 
@@ -372,7 +372,7 @@ class Command(_BaseCommand, Generic[CogT, P, T]):
         self.require_var_positional: bool = kwargs.get('require_var_positional', False)
         self.ignore_extra: bool = kwargs.get('ignore_extra', True)
         self.cooldown_after_parsing: bool = kwargs.get('cooldown_after_parsing', False)
-        self.cog: Optional[CogT] = None
+        self.cog: CogT = None
 
         # bandaid for the fact that sometimes parent can be the bot instance
         parent = kwargs.get('parent')
@@ -1321,9 +1321,8 @@ class GroupMixin(Generic[CogT]):
 
     @overload
     def command(
-        self,
+        self: GroupMixin[CogT],
         name: str = ...,
-        cls: Type[Command[CogT, P, T]] = ...,
         *args: Any,
         **kwargs: Any,
     ) -> Callable[
@@ -1339,21 +1338,29 @@ class GroupMixin(Generic[CogT]):
 
     @overload
     def command(
-        self,
+        self: GroupMixin[CogT],
         name: str = ...,
         cls: Type[CommandT] = ...,
         *args: Any,
         **kwargs: Any,
-    ) -> Callable[[Callable[Concatenate[ContextT, P], Coro[Any]]], CommandT]:
+    ) -> Callable[
+        [
+            Union[
+                Callable[Concatenate[CogT, ContextT, P], Coro[T]],
+                Callable[Concatenate[ContextT, P], Coro[T]],
+            ]
+        ],
+        CommandT,
+    ]:
         ...
 
     def command(
         self,
         name: str = MISSING,
-        cls: Type[CommandT] = MISSING,
+        cls: Type[Command] = MISSING,
         *args: Any,
         **kwargs: Any,
-    ) -> Callable[[Callable[Concatenate[ContextT, P], Coro[Any]]], CommandT]:
+    ) -> Any:
         """A shortcut decorator that invokes :func:`.command` and adds it to
         the internal command list via :meth:`~.GroupMixin.add_command`.
 
@@ -1363,7 +1370,8 @@ class GroupMixin(Generic[CogT]):
             A decorator that converts the provided method into a Command, adds it to the bot, then returns it.
         """
 
-        def decorator(func: Callable[Concatenate[ContextT, P], Coro[Any]]) -> CommandT:
+        def decorator(func):
+
             kwargs.setdefault('parent', self)
             result = command(name=name, cls=cls, *args, **kwargs)(func)
             self.add_command(result)
@@ -1373,34 +1381,46 @@ class GroupMixin(Generic[CogT]):
 
     @overload
     def group(
-        self,
+        self: GroupMixin[CogT],
         name: str = ...,
-        cls: Type[Group[CogT, P, T]] = ...,
         *args: Any,
         **kwargs: Any,
     ) -> Callable[
-        [Union[Callable[Concatenate[CogT, ContextT, P], Coro[T]], Callable[Concatenate[ContextT, P], Coro[T]]]],
+        [
+            Union[
+                Callable[Concatenate[CogT, ContextT, P], Coro[T]],
+                Callable[Concatenate[ContextT, P], Coro[T]],
+            ]
+        ],
         Group[CogT, P, T],
     ]:
         ...
 
     @overload
     def group(
-        self,
+        self: GroupMixin[CogT],
         name: str = ...,
         cls: Type[GroupT] = ...,
         *args: Any,
         **kwargs: Any,
-    ) -> Callable[[Callable[Concatenate[ContextT, P], Coro[Any]]], GroupT]:
+    ) -> Callable[
+        [
+            Union[
+                Callable[Concatenate[CogT, ContextT, P], Coro[T]],
+                Callable[Concatenate[ContextT, P], Coro[T]],
+            ]
+        ],
+        GroupT,
+    ]:
         ...
 
     def group(
         self,
         name: str = MISSING,
-        cls: Type[GroupT] = MISSING,
+        cls: Type[Group] = MISSING,
         *args: Any,
         **kwargs: Any,
-    ) -> Callable[[Callable[Concatenate[ContextT, P], Coro[Any]]], GroupT]:
+    ) -> Any:
         """A shortcut decorator that invokes :func:`.group` and adds it to
         the internal command list via :meth:`~.GroupMixin.add_command`.
 
@@ -1410,7 +1430,7 @@ class GroupMixin(Generic[CogT]):
             A decorator that converts the provided method into a Group, adds it to the bot, then returns it.
         """
 
-        def decorator(func: Callable[Concatenate[ContextT, P], Coro[Any]]) -> GroupT:
+        def decorator(func):
             kwargs.setdefault('parent', self)
             result = group(name=name, cls=cls, *args, **kwargs)(func)
             self.add_command(result)
@@ -1533,21 +1553,39 @@ class Group(GroupMixin[CogT], Command[CogT, P, T]):
 
 # Decorators
 
+if TYPE_CHECKING:
+    # Using a class to emulate a function allows for overloading the inner function in the decorator.
+
+    class _CommandDecorator:
+        @overload
+        def __call__(self, func: Callable[Concatenate[CogT, ContextT, P], Coro[T]], /) -> Command[CogT, P, T]:
+            ...
+
+        @overload
+        def __call__(self, func: Callable[Concatenate[ContextT, P], Coro[T]], /) -> Command[None, P, T]:
+            ...
+
+        def __call__(self, func: Callable[..., Coro[T]], /) -> Any:
+            ...
+
+    class _GroupDecorator:
+        @overload
+        def __call__(self, func: Callable[Concatenate[CogT, ContextT, P], Coro[T]], /) -> Group[CogT, P, T]:
+            ...
+
+        @overload
+        def __call__(self, func: Callable[Concatenate[ContextT, P], Coro[T]], /) -> Group[None, P, T]:
+            ...
+
+        def __call__(self, func: Callable[..., Coro[T]], /) -> Any:
+            ...
+
 
 @overload
 def command(
     name: str = ...,
-    cls: Type[Command[CogT, P, T]] = ...,
     **attrs: Any,
-) -> Callable[
-    [
-        Union[
-            Callable[Concatenate[CogT, ContextT, P], Coro[T]],
-            Callable[Concatenate[ContextT, P], Coro[T]],
-        ]
-    ],
-    Command[CogT, P, T],
-]:
+) -> _CommandDecorator:
     ...
 
 
@@ -1559,8 +1597,8 @@ def command(
 ) -> Callable[
     [
         Union[
-            Callable[Concatenate[CogT, ContextT, P], Coro[Any]],
             Callable[Concatenate[ContextT, P], Coro[Any]],
+            Callable[Concatenate[CogT, ContextT, P], Coro[Any]],  # type: ignore - CogT is used here to allow covariance
         ]
     ],
     CommandT,
@@ -1570,17 +1608,9 @@ def command(
 
 def command(
     name: str = MISSING,
-    cls: Type[CommandT] = MISSING,
+    cls: Type[Command] = MISSING,
     **attrs: Any,
-) -> Callable[
-    [
-        Union[
-            Callable[Concatenate[ContextT, P], Coro[Any]],
-            Callable[Concatenate[CogT, ContextT, P], Coro[T]],
-        ]
-    ],
-    Union[Command[CogT, P, T], CommandT],
-]:
+) -> Any:
     """A decorator that transforms a function into a :class:`.Command`
     or if called with :func:`.group`, :class:`.Group`.
 
@@ -1611,14 +1641,9 @@ def command(
         If the function is not a coroutine or is already a command.
     """
     if cls is MISSING:
-        cls = Command  # type: ignore
+        cls = Command
 
-    def decorator(
-        func: Union[
-            Callable[Concatenate[ContextT, P], Coro[Any]],
-            Callable[Concatenate[CogT, ContextT, P], Coro[Any]],
-        ]
-    ) -> CommandT:
+    def decorator(func):
         if isinstance(func, Command):
             raise TypeError('Callback is already a command.')
         return cls(func, name=name, **attrs)
@@ -1629,17 +1654,8 @@ def command(
 @overload
 def group(
     name: str = ...,
-    cls: Type[Group[CogT, P, T]] = ...,
     **attrs: Any,
-) -> Callable[
-    [
-        Union[
-            Callable[Concatenate[CogT, ContextT, P], Coro[T]],
-            Callable[Concatenate[ContextT, P], Coro[T]],
-        ]
-    ],
-    Group[CogT, P, T],
-]:
+) -> _GroupDecorator:
     ...
 
 
@@ -1651,7 +1667,7 @@ def group(
 ) -> Callable[
     [
         Union[
-            Callable[Concatenate[CogT, ContextT, P], Coro[Any]],
+            Callable[Concatenate[CogT, ContextT, P], Coro[Any]],  # type: ignore - CogT is used here to allow covariance
             Callable[Concatenate[ContextT, P], Coro[Any]],
         ]
     ],
@@ -1662,17 +1678,9 @@ def group(
 
 def group(
     name: str = MISSING,
-    cls: Type[GroupT] = MISSING,
+    cls: Type[Group] = MISSING,
     **attrs: Any,
-) -> Callable[
-    [
-        Union[
-            Callable[Concatenate[ContextT, P], Coro[Any]],
-            Callable[Concatenate[CogT, ContextT, P], Coro[T]],
-        ]
-    ],
-    Union[Group[CogT, P, T], GroupT],
-]:
+) -> Any:
     """A decorator that transforms a function into a :class:`.Group`.
 
     This is similar to the :func:`.command` decorator but the ``cls``
@@ -1682,8 +1690,9 @@ def group(
         The ``cls`` parameter can now be passed.
     """
     if cls is MISSING:
-        cls = Group  # type: ignore
-    return command(name=name, cls=cls, **attrs)  # type: ignore
+        cls = Group
+
+    return command(name=name, cls=cls, **attrs)
 
 
 def check(predicate: Check) -> Callable[[T], T]:

discord/ext/commands/view.py

@@ -21,7 +21,6 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 DEALINGS IN THE SOFTWARE.
 """
-
 from .errors import UnexpectedQuoteError, InvalidEndOfQuotedStringError, ExpectedClosingQuoteError
 
 # map from opening quotes to closing quotes
@@ -177,7 +176,7 @@ class StringView:
                 next_char = self.get()
                 valid_eof = not next_char or next_char.isspace()
                 if not valid_eof:
-                    raise InvalidEndOfQuotedStringError(next_char)
+                    raise InvalidEndOfQuotedStringError(next_char)  # type: ignore - this will always be a string
 
                 # we're quoted so it's okay
                 return ''.join(result)