From 18f73b985b82de1d0eb07a9e827ba53065330008 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Mon, 15 Nov 2021 14:38:01 +0900
Subject: [PATCH] Make `ModelExtensions` nullable enabled

---
 osu.Game/Extensions/ModelExtensions.cs | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/osu.Game/Extensions/ModelExtensions.cs b/osu.Game/Extensions/ModelExtensions.cs
index 2545045d96..48a3bac112 100644
--- a/osu.Game/Extensions/ModelExtensions.cs
+++ b/osu.Game/Extensions/ModelExtensions.cs
@@ -7,6 +7,8 @@ using osu.Game.Rulesets;
 using osu.Game.Scoring;
 using osu.Game.Users;
 
+#nullable enable
+
 namespace osu.Game.Extensions
 {
     public static class ModelExtensions
@@ -23,9 +25,9 @@ namespace osu.Game.Extensions
         /// extension method type inference rules cause this method to call itself and cause a stack overflow.
         /// </para>
         /// </remarks>
-        public static string GetDisplayString(this object model)
+        public static string GetDisplayString(this object? model)
         {
-            string result = null;
+            string? result = null;
 
             switch (model)
             {
@@ -65,8 +67,11 @@ namespace osu.Game.Extensions
         /// <param name="instance">The instance to compare.</param>
         /// <param name="other">The other instance to compare against.</param>
         /// <returns>Whether online IDs match. If either instance is missing an online ID, this will return false.</returns>
-        public static bool MatchesOnlineID(this IHasOnlineID<long> instance, IHasOnlineID<long> other)
+        public static bool MatchesOnlineID(this IHasOnlineID<long>? instance, IHasOnlineID<long>? other)
         {
+            if (instance == null || other == null)
+                return false;
+
             if (instance.OnlineID < 0 || other.OnlineID < 0)
                 return false;
 
@@ -79,8 +84,11 @@ namespace osu.Game.Extensions
         /// <param name="instance">The instance to compare.</param>
         /// <param name="other">The other instance to compare against.</param>
         /// <returns>Whether online IDs match. If either instance is missing an online ID, this will return false.</returns>
-        public static bool MatchesOnlineID(this IHasOnlineID<int> instance, IHasOnlineID<int> other)
+        public static bool MatchesOnlineID(this IHasOnlineID<int>? instance, IHasOnlineID<int>? other)
         {
+            if (instance == null || other == null)
+                return false;
+
             if (instance.OnlineID < 0 || other.OnlineID < 0)
                 return false;