Add setting to fallback to global command if guild command isn't found

Author: Rapptz

discord/app_commands/tree.py

@@ -113,9 +113,16 @@ class CommandTree(Generic[ClientT]):
     -----------
     client: :class:`~discord.Client`
         The client instance to get application command information from.
+    fallback_to_global: :class:`bool`
+        If a guild-specific command is not found when invoked, then try falling back into
+        a global command in the tree. For example, if the tree locally has a ``/ping`` command
+        under the global namespace but the guild has a guild-specific ``/ping``, instead of failing
+        to find the guild-specific ``/ping`` command it will fall back to the global ``/ping`` command.
+        This has the potential to raise more :exc:`~discord.app_commands.CommandSignatureMismatch` errors
+        than usual. Defaults to ``True``.
     """
 
-    def __init__(self, client: ClientT):
+    def __init__(self, client: ClientT, *, fallback_to_global: bool = True):
         self.client: ClientT = client
         self._http = client.http
         self._state = client._connection
@@ -124,6 +131,7 @@ def __init__(self, client: ClientT):
             raise ClientException('This client already has an associated command tree.')
 
         self._state._command_tree = self
+        self.fallback_to_global: bool = fallback_to_global
         self._guild_commands: Dict[int, Dict[str, Union[Command, Group]]] = {}
         self._global_commands: Dict[str, Union[Command, Group]] = {}
         # (name, guild_id, command_type): Command
@@ -935,7 +943,11 @@ async def wrapper():
     def _get_context_menu(self, data: ApplicationCommandInteractionData) -> Optional[ContextMenu]:
         name = data['name']
         guild_id = _get_as_snowflake(data, 'guild_id')
-        return self._context_menus.get((name, guild_id, data.get('type', 1)))
+        t = data.get('type', 1)
+        cmd = self._context_menus.get((name, guild_id, t))
+        if cmd is None and self.fallback_to_global:
+            return self._context_menus.get((name, None, t))
+        return cmd
 
     def _get_app_command_options(
         self, data: ApplicationCommandInteractionData
@@ -948,9 +960,11 @@ def _get_app_command_options(
             try:
                 guild_commands = self._guild_commands[command_guild_id]
             except KeyError:
-                command = None
+                command = None if not self.fallback_to_global else self._global_commands.get(name)
             else:
                 command = guild_commands.get(name)
+                if command is None and self.fallback_to_global:
+                    command = self._global_commands.get(name)
         else:
             command = self._global_commands.get(name)