[commands] Fix command parameter handling in HelpCommand

discord/ext/commands/core.py

@@ -124,12 +124,17 @@ def unwrap_function(function: Callable[..., Any]) -> Callable[..., Any]:
             return function
 
 
-def get_signature_parameters(function: Callable[..., Any], globalns: Dict[str, Any]) -> Dict[str, inspect.Parameter]:
+def get_signature_parameters(
+    function: Callable[..., Any],
+    globalns: Dict[str, Any],
+    *,
+    skip_parameters: Optional[int] = None,
+) -> Dict[str, inspect.Parameter]:
     signature = inspect.signature(function)
     params = {}
     cache: Dict[str, Any] = {}
     eval_annotation = discord.utils.evaluate_annotation
-    required_params = discord.utils.is_inside_class(function) + 1
+    required_params = discord.utils.is_inside_class(function) + 1 if skip_parameters is None else skip_parameters
     if len(signature.parameters) < required_params:
         raise TypeError(f'Command signature requires at least {required_params - 1} parameter(s)')
 

discord/ext/commands/help.py

@@ -32,7 +32,7 @@ from typing import Optional, TYPE_CHECKING
 
 import discord.utils
 
-from .core import Group, Command
+from .core import Group, Command, get_signature_parameters
 from .errors import CommandError
 
 if TYPE_CHECKING:
@@ -190,11 +190,13 @@ class _HelpCommandImpl(Command):
         super().__init__(inject.command_callback, *args, **kwargs)
         self._original = inject
         self._injected = inject
+        self.params = get_signature_parameters(inject.command_callback, globals(), skip_parameters=1)
 
     async def prepare(self, ctx):
         self._injected = injected = self._original.copy()
         injected.context = ctx
         self.callback = injected.command_callback
+        self.params = get_signature_parameters(injected.command_callback, globals(), skip_parameters=1)
 
         on_error = injected.on_help_command_error
         if not hasattr(on_error, '__help_command_not_overriden__'):
@@ -218,16 +220,6 @@ class _HelpCommandImpl(Command):
     async def _on_error_cog_implementation(self, dummy, ctx, error):
         await self._injected.on_help_command_error(ctx, error)
 
-    @property
-    def clean_params(self):
-        result = self.params.copy()
-        try:
-            del result[next(iter(result))]
-        except StopIteration:
-            raise ValueError('Missing context parameter') from None
-        else:
-            return result
-
     def _inject_into_cog(self, cog):
         # Warning: hacky