From f04aec538fa6286743147eb2e6f7c83c1b6c4a6b Mon Sep 17 00:00:00 2001
From: smoogipoo <smoogipoo@smgi.me>
Date: Wed, 14 Oct 2020 18:12:19 +0900
Subject: [PATCH] Fix MultiMod throwing exceptions when creating copies

---
 .../UserInterface/TestSceneModSettings.cs      | 18 ++++++++++++++++++
 osu.Game/Rulesets/Mods/MultiMod.cs             |  4 +++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/osu.Game.Tests/Visual/UserInterface/TestSceneModSettings.cs b/osu.Game.Tests/Visual/UserInterface/TestSceneModSettings.cs
index c5ce3751ef..0d43be3f65 100644
--- a/osu.Game.Tests/Visual/UserInterface/TestSceneModSettings.cs
+++ b/osu.Game.Tests/Visual/UserInterface/TestSceneModSettings.cs
@@ -95,6 +95,24 @@ public void TestModSettingsUnboundWhenCopied()
             AddAssert("copy has original value", () => Precision.AlmostEquals(1.5, copy.SpeedChange.Value));
         }
 
+        [Test]
+        public void TestMultiModSettingsUnboundWhenCopied()
+        {
+            MultiMod original = null;
+            MultiMod copy = null;
+
+            AddStep("create mods", () =>
+            {
+                original = new MultiMod(new OsuModDoubleTime());
+                copy = (MultiMod)original.CreateCopy();
+            });
+
+            AddStep("change property", () => ((OsuModDoubleTime)original.Mods[0]).SpeedChange.Value = 2);
+
+            AddAssert("original has new value", () => Precision.AlmostEquals(2.0, ((OsuModDoubleTime)original.Mods[0]).SpeedChange.Value));
+            AddAssert("copy has original value", () => Precision.AlmostEquals(1.5, ((OsuModDoubleTime)copy.Mods[0]).SpeedChange.Value));
+        }
+
         private void createModSelect()
         {
             AddStep("create mod select", () =>
diff --git a/osu.Game/Rulesets/Mods/MultiMod.cs b/osu.Game/Rulesets/Mods/MultiMod.cs
index f7d574d3c7..2107009dbb 100644
--- a/osu.Game/Rulesets/Mods/MultiMod.cs
+++ b/osu.Game/Rulesets/Mods/MultiMod.cs
@@ -6,7 +6,7 @@
 
 namespace osu.Game.Rulesets.Mods
 {
-    public class MultiMod : Mod
+    public sealed class MultiMod : Mod
     {
         public override string Name => string.Empty;
         public override string Acronym => string.Empty;
@@ -20,6 +20,8 @@ public MultiMod(params Mod[] mods)
             Mods = mods;
         }
 
+        public override Mod CreateCopy() => new MultiMod(Mods.Select(m => m.CreateCopy()).ToArray());
+
         public override Type[] IncompatibleMods => Mods.SelectMany(m => m.IncompatibleMods).ToArray();
     }
 }