From c9facf70f9503bd3928b3ddad35807d21df633b1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bart=C5=82omiej=20Dach?= <dach.bartlomiej@gmail.com>
Date: Fri, 14 May 2021 23:35:06 +0200
Subject: [PATCH] Use conditional nullability attribute

As it turns out, C# 8 provides an attribute that allows annotating that
an `out` parameter's nullability depends on the method's return value,
which is exactly what is desired here.
---
 osu.Game.Tests/Mods/ModUtilsTest.cs | 2 +-
 osu.Game/Utils/ModUtils.cs          | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/osu.Game.Tests/Mods/ModUtilsTest.cs b/osu.Game.Tests/Mods/ModUtilsTest.cs
index 7dcaabca3d..7384471c41 100644
--- a/osu.Game.Tests/Mods/ModUtilsTest.cs
+++ b/osu.Game.Tests/Mods/ModUtilsTest.cs
@@ -146,7 +146,7 @@ namespace osu.Game.Tests.Mods
             if (isValid)
                 Assert.IsNull(invalid);
             else
-                Assert.That(invalid?.Select(t => t.GetType()), Is.EquivalentTo(expectedInvalid));
+                Assert.That(invalid.Select(t => t.GetType()), Is.EquivalentTo(expectedInvalid));
         }
 
         public abstract class CustomMod1 : Mod
diff --git a/osu.Game/Utils/ModUtils.cs b/osu.Game/Utils/ModUtils.cs
index 596880f2e7..1c3558fc90 100644
--- a/osu.Game/Utils/ModUtils.cs
+++ b/osu.Game/Utils/ModUtils.cs
@@ -92,7 +92,7 @@ namespace osu.Game.Utils
         /// <param name="mods">The mods to check.</param>
         /// <param name="invalidMods">Invalid mods, if any were found. Can be null if all mods were valid.</param>
         /// <returns>Whether the input mods were all valid. If false, <paramref name="invalidMods"/> will contain all invalid entries.</returns>
-        public static bool CheckValidForGameplay(IEnumerable<Mod> mods, out List<Mod>? invalidMods)
+        public static bool CheckValidForGameplay(IEnumerable<Mod> mods, [NotNullWhen(false)] out List<Mod>? invalidMods)
         {
             mods = mods.ToArray();