From d9bf06e7b916a7214f00b43cb08b582485f86781 Mon Sep 17 00:00:00 2001
From: Numerlor <25886452+Numerlor@users.noreply.github.com>
Date: Tue, 10 Mar 2020 00:38:43 +0100
Subject: Retain previous channel overwrites.

Previously silencing a channel reset all overwrites excluding `send_messages`
and unsilencing them removed all overwrites.
This is prevented by getting the current overwrite
and applying it with only send_messages changed.
---
 bot/cogs/moderation/silence.py | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/bot/cogs/moderation/silence.py b/bot/cogs/moderation/silence.py
index e12b6c606..626c1ecfb 100644
--- a/bot/cogs/moderation/silence.py
+++ b/bot/cogs/moderation/silence.py
@@ -128,10 +128,14 @@ class Silence(commands.Cog):
         If `persistent` is `True` add `channel` to notifier.
         `duration` is only used for logging; if None is passed `persistent` should be True to not log None.
         """
-        if channel.overwrites_for(self._verified_role).send_messages is False:
+        current_overwrite = channel.overwrites_for(self._verified_role)
+        if current_overwrite.send_messages is False:
             log.debug(f"Tried to silence channel #{channel} ({channel.id}) but the channel was already silenced.")
             return False
-        await channel.set_permissions(self._verified_role, overwrite=PermissionOverwrite(send_messages=False))
+        await channel.set_permissions(
+            self._verified_role,
+            overwrite=PermissionOverwrite(**dict(current_overwrite, send_messages=False))
+        )
         if persistent:
             log.debug(f"Silenced #{channel} ({channel.id}) indefinitely.")
             self.notifier.add_channel(channel)
@@ -147,8 +151,12 @@ class Silence(commands.Cog):
         Check if `channel` is silenced through a `PermissionOverwrite`,
         if it is unsilence it and remove it from the notifier.
         """
-        if channel.overwrites_for(self._verified_role).send_messages is False:
-            await channel.set_permissions(self._verified_role, overwrite=None)
+        current_overwrite = channel.overwrites_for(self._verified_role)
+        if current_overwrite.send_messages is False:
+            await channel.set_permissions(
+                self._verified_role,
+                overwrite=PermissionOverwrite(**dict(current_overwrite, send_messages=True))
+            )
             log.debug(f"Unsilenced channel #{channel} ({channel.id}).")
             self.notifier.remove_channel(channel)
             return True
-- 
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