Allow some commands to fail checks silently.

For example, we don't want the mod commands to produce any kind of error
message when run by ordinary users in regular channels - these should
have the perception of being invisible and unavailable.

3 files changed, 9 insertions, 2 deletions

diff --git a/bot/cogs/moderation/management.py b/bot/cogs/moderation/management.py
index c7c19e89d..c39c7f3bc 100644
--- a/bot/cogs/moderation/management.py
+++ b/bot/cogs/moderation/management.py
@@ -291,6 +291,7 @@ class ModManagement(commands.Cog):
                 channels=constants.MODERATION_CHANNELS,
                 categories=[constants.Categories.modmail],
                 redirect=None,
+                fail_silently=True,
             )
         ]
         return all(checks)
diff --git a/bot/decorators.py b/bot/decorators.py
index 1e77afe60..500197c89 100644
--- a/bot/decorators.py
+++ b/bot/decorators.py
@@ -23,6 +23,7 @@ def in_whitelist(
     categories: Container[int] = (),
     roles: Container[int] = (),
     redirect: Optional[int] = Channels.bot_commands,
+    fail_silently: bool = False,
 ) -> Callable:
     """
     Check if a command was issued in a whitelisted context.
@@ -39,7 +40,7 @@ def in_whitelist(
     """
     def predicate(ctx: Context) -> bool:
         """Check if command was issued in a whitelisted context."""
-        return in_whitelist_check(ctx, channels, categories, roles, redirect)
+        return in_whitelist_check(ctx, channels, categories, roles, redirect, fail_silently)
 
     return commands.check(predicate)
 
diff --git a/bot/utils/checks.py b/bot/utils/checks.py
index 63568b29e..d5ebe4ec9 100644
--- a/bot/utils/checks.py
+++ b/bot/utils/checks.py
@@ -40,6 +40,7 @@ def in_whitelist_check(
     categories: Container[int] = (),
     roles: Container[int] = (),
     redirect: Optional[int] = constants.Channels.bot_commands,
+    fail_silently: bool = False,
 ) -> bool:
     """
     Check if a command was issued in a whitelisted context.
@@ -81,7 +82,11 @@ def in_whitelist_check(
         return True
 
     log.trace(f"{ctx.author} may not use the `{ctx.command.name}` command within this context.")
-    raise InWhitelistCheckFailure(redirect)
+
+    # Some commands are secret, and should produce no feedback at all.
+    if not fail_silently:
+        raise InWhitelistCheckFailure(redirect)
+    return False
 
 
 def with_role_check(ctx: Context, *role_ids: int) -> bool: