Reject bad perm kwargs in check decorators (#2289)

Also fixed a misspelled kwarg in reports.

Also now raising TypeError for an empty `@checks.has_permissions()` decorator.

Signed-off-by: Toby Harradine <tobyharradine@gmail.com>

redbot/cogs/reports/reports.py

@@ -316,7 +316,7 @@ async def on_message(self, message: discord.Message):
                 self.tunnel_store[k]["msgs"] = msgs
 
     @commands.guild_only()
-    @checks.mod_or_permissions(manage_members=True)
+    @checks.mod_or_permissions(manage_roles=True)
     @report.command(name="interact")
     async def response(self, ctx, ticket_number: int):
         """Open a message tunnel.

redbot/core/commands/requires.py

@@ -281,12 +281,14 @@ def __init__(
 
         if isinstance(user_perms, dict):
             self.user_perms: Optional[discord.Permissions] = discord.Permissions.none()
+            _validate_perms_dict(user_perms)
             self.user_perms.update(**user_perms)
         else:
             self.user_perms = user_perms
 
         if isinstance(bot_perms, dict):
             self.bot_perms: discord.Permissions = discord.Permissions.none()
+            _validate_perms_dict(bot_perms)
             self.bot_perms.update(**bot_perms)
         else:
             self.bot_perms = bot_perms
@@ -311,6 +313,7 @@ def decorator(func: "_CommandOrCoro") -> "_CommandOrCoro":
                 if user_perms is None:
                     func.requires.user_perms = None
                 else:
+                    _validate_perms_dict(user_perms)
                     func.requires.user_perms.update(**user_perms)
             return func
 
@@ -584,6 +587,7 @@ def decorator(func: "_CommandOrCoro") -> "_CommandOrCoro":
         if asyncio.iscoroutinefunction(func):
             func.__requires_bot_perms__ = perms
         else:
+            _validate_perms_dict(perms)
             func.requires.bot_perms.update(**perms)
         return func
 
@@ -595,6 +599,8 @@ def has_permissions(**perms: bool):
 
     This check can be overridden by rules.
     """
+    if perms is None:
+        raise TypeError("Must provide at least one keyword argument to has_permissions")
     return Requires.get_decorator(None, perms)
 
 
@@ -666,3 +672,20 @@ def __setitem__(self, key: Any, value: _T) -> None:
         if not isinstance(key, int):
             raise TypeError("Keys must be of type `int`")
         return super().__setitem__(key, value)
+
+
+def _validate_perms_dict(perms: Dict[str, bool]) -> None:
+    for perm, value in perms.items():
+        try:
+            attr = getattr(discord.Permissions, perm)
+        except AttributeError:
+            attr = None
+
+        if attr is None or not isinstance(attr, property):
+            # We reject invalid permissions
+            raise TypeError(f"Unknown permission name '{perm}'")
+
+        if value is not True:
+            # We reject any permission not specified as 'True', since this is the only value which
+            # makes practical sense.
+            raise TypeError(f"Permission {perm} may only be specified as 'True', not {value}")