Merge pull request #7238 from huoyaoyuan/fxcop

Apply FxCop at game side

CodeAnalysis/osu.ruleset

@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RuleSet Name="osu! Rule Set" Description=" " ToolsVersion="16.0">
+  <Rules AnalyzerId="Microsoft.CodeQuality.Analyzers" RuleNamespace="Microsoft.CodeQuality.Analyzers">
+    <Rule Id="CA1016" Action="None" />
+    <Rule Id="CA1028" Action="None" />
+    <Rule Id="CA1031" Action="None" />
+    <Rule Id="CA1034" Action="None" />
+    <Rule Id="CA1036" Action="None" />
+    <Rule Id="CA1040" Action="None" />
+    <Rule Id="CA1044" Action="None" />
+    <Rule Id="CA1051" Action="None" />
+    <Rule Id="CA1054" Action="None" />
+    <Rule Id="CA1056" Action="None" />
+    <Rule Id="CA1062" Action="None" />
+    <Rule Id="CA1063" Action="None" />
+    <Rule Id="CA1067" Action="None" />
+    <Rule Id="CA1707" Action="None" />
+    <Rule Id="CA1710" Action="None" />
+    <Rule Id="CA1714" Action="None" />
+    <Rule Id="CA1716" Action="None" />
+    <Rule Id="CA1717" Action="None" />
+    <Rule Id="CA1720" Action="None" />
+    <Rule Id="CA1721" Action="None" />
+    <Rule Id="CA1724" Action="None" />
+    <Rule Id="CA1801" Action="None" />
+    <Rule Id="CA1806" Action="None" />
+    <Rule Id="CA1812" Action="None" />
+    <Rule Id="CA1814" Action="None" />
+    <Rule Id="CA1815" Action="None" />
+    <Rule Id="CA1819" Action="None" />
+    <Rule Id="CA1822" Action="None" />
+    <Rule Id="CA1823" Action="None" />
+    <Rule Id="CA2007" Action="None" />
+    <Rule Id="CA2214" Action="None" />
+    <Rule Id="CA2227" Action="None" />
+  </Rules>
+  <Rules AnalyzerId="Microsoft.CodeQuality.CSharp.Analyzers" RuleNamespace="Microsoft.CodeQuality.CSharp.Analyzers">
+    <Rule Id="CA1001" Action="None" />
+    <Rule Id="CA1032" Action="None" />
+  </Rules>
+  <Rules AnalyzerId="Microsoft.NetCore.Analyzers" RuleNamespace="Microsoft.NetCore.Analyzers">
+    <Rule Id="CA1303" Action="None" />
+    <Rule Id="CA1304" Action="None" />
+    <Rule Id="CA1305" Action="None" />
+    <Rule Id="CA1307" Action="None" />
+    <Rule Id="CA1308" Action="None" />
+    <Rule Id="CA1816" Action="None" />
+    <Rule Id="CA1826" Action="None" />
+    <Rule Id="CA2000" Action="None" />
+    <Rule Id="CA2008" Action="None" />
+    <Rule Id="CA2213" Action="None" />
+    <Rule Id="CA2235" Action="None" />
+  </Rules>
+  <Rules AnalyzerId="Microsoft.NetCore.CSharp.Analyzers" RuleNamespace="Microsoft.NetCore.CSharp.Analyzers">
+    <Rule Id="CA1309" Action="Warning" />
+    <Rule Id="CA2201" Action="Warning" />
+  </Rules>
+</RuleSet>

Directory.Build.props

@@ -18,7 +18,11 @@
   <ItemGroup Label="Code Analysis">
     <PackageReference Include="Microsoft.CodeAnalysis.BannedApiAnalyzers" Version="2.9.8" PrivateAssets="All" />
     <AdditionalFiles Include="$(MSBuildThisFileDirectory)CodeAnalysis\BannedSymbols.txt" />
+    <PackageReference Include="Microsoft.CodeAnalysis.FxCopAnalyzers" Version="2.9.8" PrivateAssets="All" />
   </ItemGroup>
+  <PropertyGroup Label="Code Analysis">
+    <CodeAnalysisRuleSet>$(MSBuildThisFileDirectory)CodeAnalysis\osu.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
   <PropertyGroup Label="Documentation">
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <NoWarn>$(NoWarn);CS1591</NoWarn>

osu.Game.Rulesets.Catch/CatchRuleset.cs

@@ -18,6 +18,7 @@ using osu.Game.Rulesets.Catch.Beatmaps;
 using osu.Game.Rulesets.Catch.Difficulty;
 using osu.Game.Rulesets.Difficulty;
 using osu.Game.Scoring;
+using System;
 
 namespace osu.Game.Rulesets.Catch
 {
@@ -114,7 +115,7 @@ namespace osu.Game.Rulesets.Catch
                     };
 
                 default:
-                    return new Mod[] { };
+                    return Array.Empty<Mod>();
             }
         }
 

osu.Game.Rulesets.Mania/ManiaRuleset.cs

@@ -160,7 +160,7 @@ namespace osu.Game.Rulesets.Mania
                     };
 
                 default:
-                    return new Mod[] { };
+                    return Array.Empty<Mod>();
             }
         }
 
@@ -270,7 +270,7 @@ namespace osu.Game.Rulesets.Mania
                     return stage1Bindings.Concat(stage2Bindings);
             }
 
-            return new KeyBinding[0];
+            return Array.Empty<KeyBinding>();
         }
 
         public override string GetVariantName(int variant)

osu.Game.Rulesets.Osu/OsuRuleset.cs

@@ -26,6 +26,7 @@ using osu.Game.Rulesets.Osu.Difficulty;
 using osu.Game.Rulesets.Osu.Skinning;
 using osu.Game.Scoring;
 using osu.Game.Skinning;
+using System;
 
 namespace osu.Game.Rulesets.Osu
 {
@@ -151,7 +152,7 @@ namespace osu.Game.Rulesets.Osu
                     };
 
                 default:
-                    return new Mod[] { };
+                    return Array.Empty<Mod>();
             }
         }
 

osu.Game.Rulesets.Taiko/Objects/Drawables/DrawableTaikoHitObject.cs

@@ -105,19 +105,19 @@ namespace osu.Game.Rulesets.Taiko.Objects.Drawables
         }
     }
 
-    public abstract class DrawableTaikoHitObject<TaikoHitType> : DrawableTaikoHitObject
+    public abstract class DrawableTaikoHitObject<TTaikoHit> : DrawableTaikoHitObject
-        where TaikoHitType : TaikoHitObject
+        where TTaikoHit : TaikoHitObject
     {
         public override Vector2 OriginPosition => new Vector2(DrawHeight / 2);
 
-        public new TaikoHitType HitObject;
+        public new TTaikoHit HitObject;
 
         protected readonly Vector2 BaseSize;
         protected readonly TaikoPiece MainPiece;
 
         private readonly Container<DrawableStrongNestedHit> strongHitContainer;
 
-        protected DrawableTaikoHitObject(TaikoHitType hitObject)
+        protected DrawableTaikoHitObject(TTaikoHit hitObject)
             : base(hitObject)
         {
             HitObject = hitObject;

osu.Game.Rulesets.Taiko/TaikoRuleset.cs

@@ -18,6 +18,7 @@ using osu.Game.Rulesets.Difficulty;
 using osu.Game.Rulesets.Taiko.Beatmaps;
 using osu.Game.Rulesets.Taiko.Difficulty;
 using osu.Game.Scoring;
+using System;
 
 namespace osu.Game.Rulesets.Taiko
 {
@@ -113,7 +114,7 @@ namespace osu.Game.Rulesets.Taiko
                     };
 
                 default:
-                    return new Mod[] { };
+                    return Array.Empty<Mod>();
             }
         }
 

osu.Game.Tests/NonVisual/LimitedCapacityStackTest.cs

@@ -25,7 +25,7 @@ namespace osu.Game.Tests.NonVisual
         {
             Assert.AreEqual(0, stack.Count);
 
-            Assert.Throws<IndexOutOfRangeException>(() =>
+            Assert.Throws<ArgumentOutOfRangeException>(() =>
             {
                 int unused = stack[0];
             });
@@ -55,7 +55,7 @@ namespace osu.Game.Tests.NonVisual
             // e.g. indices 3, 4, 5, 6 (out of range)
             for (int i = stack.Count; i < stack.Count + capacity; i++)
             {
-                Assert.Throws<IndexOutOfRangeException>(() =>
+                Assert.Throws<ArgumentOutOfRangeException>(() =>
                 {
                     int unused = stack[i];
                 });
@@ -80,7 +80,7 @@ namespace osu.Game.Tests.NonVisual
             // e.g. indices 3, 4, 5, 6 (out of range)
             for (int i = stack.Count; i < stack.Count + capacity; i++)
             {
-                Assert.Throws<IndexOutOfRangeException>(() =>
+                Assert.Throws<ArgumentOutOfRangeException>(() =>
                 {
                     int unused = stack[i];
                 });

osu.Game.Tests/Visual/Gameplay/TestSceneSkipOverlay.cs

@@ -1,6 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
 using System.Linq;
 using NUnit.Framework;
 using osu.Framework.Graphics;
@@ -31,7 +32,7 @@ namespace osu.Game.Tests.Visual.Gameplay
             requestCount = 0;
             increment = skip_time;
 
-            Child = gameplayClockContainer = new GameplayClockContainer(CreateWorkingBeatmap(CreateBeatmap(new OsuRuleset().RulesetInfo)), new Mod[] { }, 0)
+            Child = gameplayClockContainer = new GameplayClockContainer(CreateWorkingBeatmap(CreateBeatmap(new OsuRuleset().RulesetInfo)), Array.Empty<Mod>(), 0)
             {
                 RelativeSizeAxes = Axes.Both,
                 Children = new Drawable[]

osu.Game.Tests/Visual/Multiplayer/TestSceneMatchParticipants.cs

@@ -45,7 +45,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
             });
 
             AddStep(@"set max", () => Room.MaxParticipants.Value = 10);
-            AddStep(@"clear users", () => Room.Participants.Value = new User[] { });
+            AddStep(@"clear users", () => Room.Participants.Value = System.Array.Empty<User>());
             AddStep(@"set max to null", () => Room.MaxParticipants.Value = null);
         }
     }

osu.Game.Tests/Visual/Online/TestSceneUserProfileOverlay.cs

@@ -70,7 +70,7 @@ namespace osu.Game.Tests.Visual.Online
             },
             Title = "osu!volunteer",
             Colour = "ff0000",
-            Achievements = new User.UserAchievement[0],
+            Achievements = Array.Empty<User.UserAchievement>(),
         };
 
         public TestSceneUserProfileOverlay()

osu.Game.Tests/Visual/Online/TestSceneUserProfilePreviousUsernames.cs

@@ -42,7 +42,7 @@ namespace osu.Game.Tests.Visual.Online
                 new User { PreviousUsernames = new[] { "longusername", "longerusername" } },
                 new User { PreviousUsernames = new[] { "test", "angelsim", "verylongusername" } },
                 new User { PreviousUsernames = new[] { "ihavenoidea", "howcani", "makethistext", "anylonger" } },
-                new User { PreviousUsernames = new string[0] },
+                new User { PreviousUsernames = Array.Empty<string>() },
                 null
             };
 

osu.Game.Tests/Visual/TestSceneOsuGame.cs

@@ -111,7 +111,7 @@ namespace osu.Game.Tests.Visual
                 foreach (var type in requiredGameDependencies)
                 {
                     if (game.Dependencies.Get(type) == null)
-                        throw new Exception($"{type} has not been cached");
+                        throw new InvalidOperationException($"{type} has not been cached");
                 }
 
                 return true;
@@ -121,7 +121,7 @@ namespace osu.Game.Tests.Visual
                 foreach (var type in requiredGameBaseDependencies)
                 {
                     if (gameBase.Dependencies.Get(type) == null)
-                        throw new Exception($"{type} has not been cached");
+                        throw new InvalidOperationException($"{type} has not been cached");
                 }
 
                 return true;

osu.Game.Tournament/Screens/Editors/LadderEditorScreen.cs

@@ -49,7 +49,7 @@ namespace osu.Game.Tournament.Screens.Editors
             get
             {
                 if (editorInfo == null)
-                    return new MenuItem[0];
+                    return Array.Empty<MenuItem>();
 
                 return new MenuItem[]
                 {

osu.Game.Tournament/Screens/Ladder/Components/DrawableMatchTeam.cs

@@ -192,7 +192,7 @@ namespace osu.Game.Tournament.Screens.Ladder.Components
             get
             {
                 if (editorInfo == null)
-                    return new MenuItem[0];
+                    return Array.Empty<MenuItem>();
 
                 return new MenuItem[]
                 {

osu.Game/Beatmaps/BeatmapInfo.cs

@@ -98,7 +98,7 @@ namespace osu.Game.Beatmaps
             {
                 if (string.IsNullOrEmpty(value))
                 {
-                    Bookmarks = new int[0];
+                    Bookmarks = Array.Empty<int>();
                     return;
                 }
 
@@ -111,7 +111,7 @@ namespace osu.Game.Beatmaps
         }
 
         [NotMapped]
-        public int[] Bookmarks { get; set; } = new int[0];
+        public int[] Bookmarks { get; set; } = Array.Empty<int>();
 
         public double DistanceSpacing { get; set; }
         public int BeatDivisor { get; set; }

osu.Game/Beatmaps/BeatmapManager_WorkingBeatmap.cs

@@ -42,7 +42,7 @@ namespace osu.Game.Beatmaps
                 }
             }
 
-            private string getPathForFile(string filename) => BeatmapSetInfo.Files.FirstOrDefault(f => string.Equals(f.Filename, filename, StringComparison.InvariantCultureIgnoreCase))?.FileInfo.StoragePath;
+            private string getPathForFile(string filename) => BeatmapSetInfo.Files.FirstOrDefault(f => string.Equals(f.Filename, filename, StringComparison.OrdinalIgnoreCase))?.FileInfo.StoragePath;
 
             private TextureStore textureStore;
 

osu.Game/Beatmaps/ControlPoints/SampleControlPoint.cs

@@ -70,6 +70,6 @@ namespace osu.Game.Beatmaps.ControlPoints
 
         public override bool EquivalentTo(ControlPoint other) =>
             other is SampleControlPoint otherTyped &&
-            string.Equals(SampleBank, otherTyped.SampleBank) && SampleVolume == otherTyped.SampleVolume;
+            SampleBank == otherTyped.SampleBank && SampleVolume == otherTyped.SampleVolume;
     }
 }

osu.Game/Beatmaps/DummyWorkingBeatmap.cs

@@ -55,7 +55,7 @@ namespace osu.Game.Beatmaps
 
             private class DummyRuleset : Ruleset
             {
-                public override IEnumerable<Mod> GetModsFor(ModType type) => new Mod[] { };
+                public override IEnumerable<Mod> GetModsFor(ModType type) => Array.Empty<Mod>();
 
                 public override DrawableRuleset CreateDrawableRulesetWith(IBeatmap beatmap, IReadOnlyList<Mod> mods = null)
                 {

osu.Game/Database/MutableDatabaseBackedStoreWithFileIncludes.cs

@@ -7,9 +7,9 @@ using osu.Framework.Platform;
 
 namespace osu.Game.Database
 {
-    public abstract class MutableDatabaseBackedStoreWithFileIncludes<T, U> : MutableDatabaseBackedStore<T>
+    public abstract class MutableDatabaseBackedStoreWithFileIncludes<T, TFileInfo> : MutableDatabaseBackedStore<T>
-        where T : class, IHasPrimaryKey, ISoftDelete, IHasFiles<U>
+        where T : class, IHasPrimaryKey, ISoftDelete, IHasFiles<TFileInfo>
-        where U : INamedFileInfo
+        where TFileInfo : INamedFileInfo
     {
         protected MutableDatabaseBackedStoreWithFileIncludes(IDatabaseContextFactory contextFactory, Storage storage = null)
             : base(contextFactory, storage)

osu.Game/Graphics/ScreenshotManager.cs

@@ -119,7 +119,7 @@ namespace osu.Game.Graphics
                         break;
 
                     default:
-                        throw new ArgumentOutOfRangeException(nameof(screenshotFormat));
+                        throw new InvalidOperationException($"Unknown enum member {nameof(ScreenshotFormat)} {screenshotFormat.Value}.");
                 }
 
                 notificationOverlay.Post(new SimpleNotification

osu.Game/Graphics/UserInterfaceV2/LabelledComponent.cs

@@ -7,15 +7,15 @@ using osu.Framework.Graphics.UserInterface;
 
 namespace osu.Game.Graphics.UserInterfaceV2
 {
-    public abstract class LabelledComponent<T, U> : LabelledDrawable<T>, IHasCurrentValue<U>
+    public abstract class LabelledComponent<TDrawable, TValue> : LabelledDrawable<TDrawable>, IHasCurrentValue<TValue>
-        where T : Drawable, IHasCurrentValue<U>
+        where TDrawable : Drawable, IHasCurrentValue<TValue>
     {
         protected LabelledComponent(bool padded)
             : base(padded)
         {
         }
 
-        public Bindable<U> Current
+        public Bindable<TValue> Current
         {
             get => Component.Current;
             set => Component.Current = value;

osu.Game/IO/Legacy/SerializationReader.cs

@@ -116,13 +116,13 @@ namespace osu.Game.IO.Legacy
         }
 
         /// <summary> Reads a generic Dictionary from the buffer. </summary>
-        public IDictionary<T, U> ReadDictionary<T, U>()
+        public IDictionary<TKey, TValue> ReadDictionary<TKey, TValue>()
         {
             int count = ReadInt32();
             if (count < 0) return null;
 
-            IDictionary<T, U> d = new Dictionary<T, U>();
+            IDictionary<TKey, TValue> d = new Dictionary<TKey, TValue>();
-            for (int i = 0; i < count; i++) d[(T)ReadObject()] = (U)ReadObject();
+            for (int i = 0; i < count; i++) d[(TKey)ReadObject()] = (TValue)ReadObject();
             return d;
         }
 
@@ -192,7 +192,7 @@ namespace osu.Game.IO.Legacy
             }
         }
 
-        public class DynamicDeserializer
+        public static class DynamicDeserializer
         {
             private static VersionConfigToNamespaceAssemblyObjectBinder versionBinder;
             private static BinaryFormatter formatter;

osu.Game/IO/Legacy/SerializationWriter.cs

@@ -102,7 +102,7 @@ namespace osu.Game.IO.Legacy
         }
 
         /// <summary> Writes a generic IDictionary to the buffer. </summary>
-        public void Write<T, U>(IDictionary<T, U> d)
+        public void Write<TKey, TValue>(IDictionary<TKey, TValue> d)
         {
             if (d == null)
             {
@@ -112,7 +112,7 @@ namespace osu.Game.IO.Legacy
             {
                 Write(d.Count);
 
-                foreach (KeyValuePair<T, U> kvp in d)
+                foreach (KeyValuePair<TKey, TValue> kvp in d)
                 {
                     WriteObject(kvp.Key);
                     WriteObject(kvp.Value);

osu.Game/Online/API/APIAccess.cs

@@ -10,6 +10,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Newtonsoft.Json.Linq;
 using osu.Framework.Bindables;
+using osu.Framework.Extensions.ExceptionExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Logging;
 using osu.Game.Configuration;
@@ -249,7 +250,7 @@ namespace osu.Game.Online.API
                 catch
                 {
                     // if we couldn't deserialize the error message let's throw the original exception outwards.
-                    throw e;
+                    e.Rethrow();
                 }
             }
 

osu.Game/Online/API/APIRequest.cs

@@ -122,7 +122,7 @@ namespace osu.Game.Online.API
                     // attempt to decode a displayable error string.
                     var error = JsonConvert.DeserializeObject<DisplayableError>(responseString);
                     if (error != null)
-                        e = new Exception(error.ErrorMessage, e);
+                        e = new APIException(error.ErrorMessage, e);
                 }
                 catch
                 {
@@ -154,6 +154,14 @@ namespace osu.Game.Online.API
         }
     }
 
+    public class APIException : InvalidOperationException
+    {
+        public APIException(string messsage, Exception innerException)
+            : base(messsage, innerException)
+        {
+        }
+    }
+
     public delegate void APIFailureHandler(Exception e);
 
     public delegate void APISuccessHandler();

osu.Game/Online/Leaderboards/Leaderboard.cs

@@ -19,7 +19,7 @@ using osuTK.Graphics;
 
 namespace osu.Game.Online.Leaderboards
 {
-    public abstract class Leaderboard<TScope, ScoreInfo> : Container, IOnlineComponent
+    public abstract class Leaderboard<TScope, TScoreInfo> : Container, IOnlineComponent
     {
         private const double fade_duration = 300;
 
@@ -39,9 +39,9 @@ namespace osu.Game.Online.Leaderboards
 
         protected override Container<Drawable> Content => content;
 
-        private IEnumerable<ScoreInfo> scores;
+        private IEnumerable<TScoreInfo> scores;
 
-        public IEnumerable<ScoreInfo> Scores
+        public IEnumerable<TScoreInfo> Scores
         {
             get => scores;
             set
@@ -288,7 +288,7 @@ namespace osu.Game.Online.Leaderboards
         /// </summary>
         /// <param name="scoresCallback">A callback which should be called when fetching is completed. Scheduling is not required.</param>
         /// <returns>An <see cref="APIRequest"/> responsible for the fetch operation. This will be queued and performed automatically.</returns>
-        protected abstract APIRequest FetchScores(Action<IEnumerable<ScoreInfo>> scoresCallback);
+        protected abstract APIRequest FetchScores(Action<IEnumerable<TScoreInfo>> scoresCallback);
 
         private Placeholder currentPlaceholder;
 
@@ -359,6 +359,6 @@ namespace osu.Game.Online.Leaderboards
             }
         }
 
-        protected abstract LeaderboardScore CreateDrawableScore(ScoreInfo model, int index);
+        protected abstract LeaderboardScore CreateDrawableScore(TScoreInfo model, int index);
     }
 }

osu.Game/Overlays/DirectOverlay.cs

@@ -116,7 +116,7 @@ namespace osu.Game.Overlays
 
             Filter.Search.Current.ValueChanged += text =>
             {
-                if (text.NewValue != string.Empty)
+                if (!string.IsNullOrEmpty(text.NewValue))
                 {
                     Header.Tabs.Current.Value = DirectTab.Search;
 

osu.Game/Overlays/Mods/ModSection.cs

@@ -81,7 +81,7 @@ namespace osu.Game.Overlays.Mods
             }
         }
 
-        private ModButton[] buttons = { };
+        private ModButton[] buttons = Array.Empty<ModButton>();
 
         protected override bool OnKeyDown(KeyDownEvent e)
         {

osu.Game/Overlays/Music/PlaylistList.cs

@@ -239,7 +239,7 @@ namespace osu.Game.Overlays.Music
 
             private class ItemSearchContainer : FillFlowContainer<PlaylistItem>, IHasFilterableChildren
             {
-                public IEnumerable<string> FilterTerms => new string[] { };
+                public IEnumerable<string> FilterTerms => Array.Empty<string>();
 
                 public bool MatchingFilter
                 {

osu.Game/Overlays/OverlayHeaderTabControl.cs

@@ -12,7 +12,7 @@ namespace osu.Game.Overlays
             AccentColour = AccentColour,
         };
 
-        private class OverlayHeaderTabItem : OverlayTabItem<string>
+        private class OverlayHeaderTabItem : OverlayTabItem
         {
             public OverlayHeaderTabItem(string value)
                 : base(value)

osu.Game/Overlays/OverlayTabControl.cs

@@ -32,7 +32,7 @@ namespace osu.Game.Overlays
 
                 foreach (TabItem<T> tabItem in TabContainer)
                 {
-                    ((OverlayTabItem<T>)tabItem).AccentColour = value;
+                    ((OverlayTabItem)tabItem).AccentColour = value;
                 }
             }
         }
@@ -59,9 +59,9 @@ namespace osu.Game.Overlays
 
         protected override Dropdown<T> CreateDropdown() => null;
 
-        protected override TabItem<T> CreateTabItem(T value) => new OverlayTabItem<T>(value);
+        protected override TabItem<T> CreateTabItem(T value) => new OverlayTabItem(value);
 
-        protected class OverlayTabItem<U> : TabItem<U>
+        protected class OverlayTabItem : TabItem<T>
         {
             private readonly ExpandingBar bar;
 
@@ -84,7 +84,7 @@ namespace osu.Game.Overlays
                 }
             }
 
-            public OverlayTabItem(U value)
+            public OverlayTabItem(T value)
                 : base(value)
             {
                 AutoSizeAxes = Axes.X;

osu.Game/Overlays/Settings/SettingsSlider.cs

@@ -12,11 +12,11 @@ namespace osu.Game.Overlays.Settings
     {
     }
 
-    public class SettingsSlider<T, U> : SettingsItem<T>
+    public class SettingsSlider<TValue, TSlider> : SettingsItem<TValue>
-        where T : struct, IEquatable<T>, IComparable<T>, IConvertible
+        where TValue : struct, IEquatable<TValue>, IComparable<TValue>, IConvertible
-        where U : OsuSliderBar<T>, new()
+        where TSlider : OsuSliderBar<TValue>, new()
     {
-        protected override Drawable CreateControl() => new U
+        protected override Drawable CreateControl() => new TSlider
         {
             Margin = new MarginPadding { Top = 5, Bottom = 5 },
             RelativeSizeAxes = Axes.X
@@ -24,14 +24,14 @@ namespace osu.Game.Overlays.Settings
 
         public bool TransferValueOnCommit
         {
-            get => ((U)Control).TransferValueOnCommit;
+            get => ((TSlider)Control).TransferValueOnCommit;
-            set => ((U)Control).TransferValueOnCommit = value;
+            set => ((TSlider)Control).TransferValueOnCommit = value;
         }
 
         public float KeyboardStep
         {
-            get => ((U)Control).KeyboardStep;
+            get => ((TSlider)Control).KeyboardStep;
-            set => ((U)Control).KeyboardStep = value;
+            set => ((TSlider)Control).KeyboardStep = value;
         }
     }
 }

osu.Game/Overlays/UserProfileOverlay.cs

@@ -1,6 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
 using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
@@ -55,10 +56,7 @@ namespace osu.Game.Overlays
                     new BeatmapsSection(),
                     new KudosuSection()
                 }
-                : new ProfileSection[]
+                : Array.Empty<ProfileSection>();
-                {
-                    //new AboutSection(),
-                };
 
             tabs = new ProfileTabControl
             {
@@ -167,7 +165,7 @@ namespace osu.Game.Overlays
                 AccentColour = colours.Seafoam;
             }
 
-            private class ProfileTabItem : OverlayTabItem<ProfileSection>
+            private class ProfileTabItem : OverlayTabItem
             {
                 public ProfileTabItem(ProfileSection value)
                     : base(value)

osu.Game/Rulesets/Difficulty/Utils/LimitedCapacityStack.cs

@@ -28,7 +28,7 @@ namespace osu.Game.Rulesets.Difficulty.Utils
         public LimitedCapacityStack(int capacity)
         {
             if (capacity < 0)
-                throw new ArgumentOutOfRangeException();
+                throw new ArgumentOutOfRangeException(nameof(capacity));
 
             this.capacity = capacity;
             array = new T[capacity];
@@ -44,7 +44,7 @@ namespace osu.Game.Rulesets.Difficulty.Utils
             get
             {
                 if (i < 0 || i > Count - 1)
-                    throw new IndexOutOfRangeException();
+                    throw new ArgumentOutOfRangeException(nameof(i));
 
                 i += marker;
                 if (i > capacity - 1)

osu.Game/Rulesets/Mods/Mod.cs

@@ -64,7 +64,7 @@ namespace osu.Game.Rulesets.Mods
         /// The mods this mod cannot be enabled with.
         /// </summary>
         [JsonIgnore]
-        public virtual Type[] IncompatibleMods => new Type[] { };
+        public virtual Type[] IncompatibleMods => Array.Empty<Type>();
 
         /// <summary>
         /// Creates a copy of this <see cref="Mod"/> initialised to a default state.

osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs

@@ -150,8 +150,8 @@ namespace osu.Game.Rulesets.Objects.Drawables
 
             if (HitObject.SampleControlPoint == null)
             {
-                throw new ArgumentNullException(nameof(HitObject.SampleControlPoint), $"{nameof(HitObject)}s must always have an attached {nameof(HitObject.SampleControlPoint)}."
+                throw new InvalidOperationException($"{nameof(HitObject)}s must always have an attached {nameof(HitObject.SampleControlPoint)}."
-                                                                                      + $" This is an indication that {nameof(HitObject.ApplyDefaults)} has not been invoked on {this}.");
+                                                    + $" This is an indication that {nameof(HitObject.ApplyDefaults)} has not been invoked on {this}.");
             }
 
             samples = samples.Select(s => HitObject.SampleControlPoint.ApplyTo(s)).ToArray();

osu.Game/Rulesets/Objects/Legacy/ConvertHitObjectParser.cs

@@ -118,7 +118,7 @@ namespace osu.Game.Rulesets.Objects.Legacy
                 int repeatCount = Parsing.ParseInt(split[6]);
 
                 if (repeatCount > 9000)
-                    throw new ArgumentOutOfRangeException(nameof(repeatCount), @"Repeat count is way too high");
+                    throw new FormatException(@"Repeat count is way too high");
 
                 // osu-stable treated the first span of the slider as a repeat, but no repeats are happening
                 repeatCount = Math.Max(0, repeatCount - 1);

osu.Game/Rulesets/Ruleset.cs

@@ -42,7 +42,7 @@ namespace osu.Game.Rulesets
         /// </summary>
         /// <param name="mods">The legacy enum which will be converted</param>
         /// <returns>An enumerable of constructed <see cref="Mod"/>s</returns>
-        public virtual IEnumerable<Mod> ConvertLegacyMods(LegacyMods mods) => new Mod[] { };
+        public virtual IEnumerable<Mod> ConvertLegacyMods(LegacyMods mods) => Array.Empty<Mod>();
 
         public ModAutoplay GetAutoplayMod() => GetAllMods().OfType<ModAutoplay>().First();
 
@@ -116,7 +116,7 @@ namespace osu.Game.Rulesets
         /// </summary>
         /// <param name="variant">A variant.</param>
         /// <returns>A list of valid <see cref="KeyBinding"/>s.</returns>
-        public virtual IEnumerable<KeyBinding> GetDefaultKeyBindings(int variant = 0) => new KeyBinding[] { };
+        public virtual IEnumerable<KeyBinding> GetDefaultKeyBindings(int variant = 0) => Array.Empty<KeyBinding>();
 
         /// <summary>
         /// Gets the name for a key binding variant. This is used for display in the settings overlay.

osu.Game/Rulesets/Scoring/HitWindows.cs

@@ -165,7 +165,7 @@ namespace osu.Game.Rulesets.Scoring
                     return miss;
 
                 default:
-                    throw new ArgumentException(nameof(result));
+                    throw new ArgumentException("Unknown enum member", nameof(result));
             }
         }
 

osu.Game/Rulesets/UI/DrawableRuleset.cs

@@ -515,34 +515,34 @@ namespace osu.Game.Rulesets.UI
 
         public Stream GetStream(string name) => primary.GetStream(name) ?? secondary.GetStream(name);
 
-        public IEnumerable<string> GetAvailableResources() => throw new NotImplementedException();
+        public IEnumerable<string> GetAvailableResources() => throw new NotSupportedException();
 
-        public void AddAdjustment(AdjustableProperty type, BindableNumber<double> adjustBindable) => throw new NotImplementedException();
+        public void AddAdjustment(AdjustableProperty type, BindableNumber<double> adjustBindable) => throw new NotSupportedException();
 
-        public void RemoveAdjustment(AdjustableProperty type, BindableNumber<double> adjustBindable) => throw new NotImplementedException();
+        public void RemoveAdjustment(AdjustableProperty type, BindableNumber<double> adjustBindable) => throw new NotSupportedException();
 
-        public BindableNumber<double> Volume => throw new NotImplementedException();
+        public BindableNumber<double> Volume => throw new NotSupportedException();
 
-        public BindableNumber<double> Balance => throw new NotImplementedException();
+        public BindableNumber<double> Balance => throw new NotSupportedException();
 
-        public BindableNumber<double> Frequency => throw new NotImplementedException();
+        public BindableNumber<double> Frequency => throw new NotSupportedException();
 
-        public BindableNumber<double> Tempo => throw new NotImplementedException();
+        public BindableNumber<double> Tempo => throw new NotSupportedException();
 
-        public IBindable<double> GetAggregate(AdjustableProperty type) => throw new NotImplementedException();
+        public IBindable<double> GetAggregate(AdjustableProperty type) => throw new NotSupportedException();
 
-        public IBindable<double> AggregateVolume => throw new NotImplementedException();
+        public IBindable<double> AggregateVolume => throw new NotSupportedException();
 
-        public IBindable<double> AggregateBalance => throw new NotImplementedException();
+        public IBindable<double> AggregateBalance => throw new NotSupportedException();
 
-        public IBindable<double> AggregateFrequency => throw new NotImplementedException();
+        public IBindable<double> AggregateFrequency => throw new NotSupportedException();
 
-        public IBindable<double> AggregateTempo => throw new NotImplementedException();
+        public IBindable<double> AggregateTempo => throw new NotSupportedException();
 
         public int PlaybackConcurrency
         {
-            get => throw new NotImplementedException();
+            get => throw new NotSupportedException();
-            set => throw new NotImplementedException();
+            set => throw new NotSupportedException();
         }
 
         public void Dispose()

osu.Game/Scoring/ScoreManager.cs

@@ -57,7 +57,7 @@ namespace osu.Game.Scoring
         }
 
         protected override IEnumerable<string> GetStableImportPaths(Storage stableStorage)
-            => stableStorage.GetFiles(ImportFromStablePath).Where(p => HandledExtensions.Any(ext => Path.GetExtension(p)?.Equals(ext, StringComparison.InvariantCultureIgnoreCase) ?? false));
+            => stableStorage.GetFiles(ImportFromStablePath).Where(p => HandledExtensions.Any(ext => Path.GetExtension(p)?.Equals(ext, StringComparison.OrdinalIgnoreCase) ?? false));
 
         public Score GetScore(ScoreInfo score) => new LegacyDatabasedScore(score, rulesets, beatmaps(), Files.Store);
 

osu.Game/Screens/Play/ReplayPlayerLoader.cs

@@ -15,7 +15,7 @@ namespace osu.Game.Screens.Play
             : base(() => new ReplayPlayer(score))
         {
             if (score.Replay == null)
-                throw new ArgumentNullException(nameof(score.Replay), $"{nameof(score)} must have a non-null {nameof(score.Replay)}.");
+                throw new ArgumentException($"{nameof(score)} must have a non-null {nameof(score.Replay)}.", nameof(score));
 
             scoreInfo = score.ScoreInfo;
         }

osu.Game/Screens/Play/SquareGraph.cs

@@ -38,7 +38,7 @@ namespace osu.Game.Screens.Play
             }
         }
 
-        private float[] calculatedValues = { }; // values but adjusted to fit the amount of columns
+        private float[] calculatedValues = Array.Empty<float>(); // values but adjusted to fit the amount of columns
 
         private int[] values;
 

osu.Game/Screens/Select/Carousel/CarouselBeatmapSet.cs

@@ -37,13 +37,13 @@ namespace osu.Game.Screens.Select.Carousel
             {
                 default:
                 case SortMode.Artist:
-                    return string.Compare(BeatmapSet.Metadata.Artist, otherSet.BeatmapSet.Metadata.Artist, StringComparison.InvariantCultureIgnoreCase);
+                    return string.Compare(BeatmapSet.Metadata.Artist, otherSet.BeatmapSet.Metadata.Artist, StringComparison.OrdinalIgnoreCase);
 
                 case SortMode.Title:
-                    return string.Compare(BeatmapSet.Metadata.Title, otherSet.BeatmapSet.Metadata.Title, StringComparison.InvariantCultureIgnoreCase);
+                    return string.Compare(BeatmapSet.Metadata.Title, otherSet.BeatmapSet.Metadata.Title, StringComparison.OrdinalIgnoreCase);
 
                 case SortMode.Author:
-                    return string.Compare(BeatmapSet.Metadata.Author.Username, otherSet.BeatmapSet.Metadata.Author.Username, StringComparison.InvariantCultureIgnoreCase);
+                    return string.Compare(BeatmapSet.Metadata.Author.Username, otherSet.BeatmapSet.Metadata.Author.Username, StringComparison.OrdinalIgnoreCase);
 
                 case SortMode.DateAdded:
                     return otherSet.BeatmapSet.DateAdded.CompareTo(BeatmapSet.DateAdded);

osu.Game/Screens/Select/Details/FailRetryGraph.cs

@@ -27,8 +27,8 @@ namespace osu.Game.Screens.Select.Details
 
                 metrics = value;
 
-                var retries = Metrics?.Retries ?? new int[0];
+                var retries = Metrics?.Retries ?? Array.Empty<int>();
-                var fails = Metrics?.Fails ?? new int[0];
+                var fails = Metrics?.Fails ?? Array.Empty<int>();
 
                 float maxValue = fails.Any() ? fails.Zip(retries, (fail, retry) => fail + retry).Max() : 0;
                 failGraph.MaxValue = maxValue;

osu.Game/Screens/Select/FilterCriteria.cs

@@ -105,7 +105,7 @@ namespace osu.Game.Screens.Select
 
             public string SearchTerm;
 
-            public bool Equals(OptionalTextFilter other) => SearchTerm?.Equals(other.SearchTerm) ?? true;
+            public bool Equals(OptionalTextFilter other) => SearchTerm == other.SearchTerm;
         }
     }
 }

osu.Game/Skinning/LegacySkinResourceStore.cs

@@ -34,7 +34,7 @@ namespace osu.Game.Skinning
         }
 
         private string getPathForFile(string filename) =>
-            source.Files.Find(f => string.Equals(f.Filename, filename, StringComparison.InvariantCultureIgnoreCase))?.FileInfo.StoragePath;
+            source.Files.Find(f => string.Equals(f.Filename, filename, StringComparison.OrdinalIgnoreCase))?.FileInfo.StoragePath;
 
         public override IEnumerable<string> GetAvailableResources() => source.Files.Select(f => f.Filename);
     }

osu.Game/Storyboards/Drawables/DrawableStoryboardAnimation.cs

@@ -71,7 +71,7 @@ namespace osu.Game.Storyboards.Drawables
             {
                 var framePath = Animation.Path.Replace(".", frame + ".");
 
-                var path = beatmap.Value.BeatmapSetInfo.Files.Find(f => f.Filename.Equals(framePath, StringComparison.InvariantCultureIgnoreCase))?.FileInfo.StoragePath;
+                var path = beatmap.Value.BeatmapSetInfo.Files.Find(f => f.Filename.Equals(framePath, StringComparison.OrdinalIgnoreCase))?.FileInfo.StoragePath;
                 if (path == null)
                     continue;
 

osu.Game/Storyboards/Drawables/DrawableStoryboardSprite.cs

@@ -66,7 +66,7 @@ namespace osu.Game.Storyboards.Drawables
         [BackgroundDependencyLoader]
         private void load(IBindable<WorkingBeatmap> beatmap, TextureStore textureStore)
         {
-            var path = beatmap.Value.BeatmapSetInfo?.Files?.Find(f => f.Filename.Equals(Sprite.Path, StringComparison.InvariantCultureIgnoreCase))?.FileInfo.StoragePath;
+            var path = beatmap.Value.BeatmapSetInfo?.Files?.Find(f => f.Filename.Equals(Sprite.Path, StringComparison.OrdinalIgnoreCase))?.FileInfo.StoragePath;
             if (path == null)
                 return;
 

osu.Game/Users/UserPanel.cs

@@ -63,7 +63,7 @@ namespace osu.Game.Users
         private void load(UserProfileOverlay profile)
         {
             if (colours == null)
-                throw new ArgumentNullException(nameof(colours));
+                throw new InvalidOperationException($"{nameof(colours)} not initialized!");
 
             FillFlowContainer infoContainer;
 

osu.sln

@@ -60,6 +60,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		global.json = global.json
 		osu.Android.props = osu.Android.props
 		osu.iOS.props = osu.iOS.props
+		CodeAnalysis\osu.ruleset = CodeAnalysis\osu.ruleset
 		osu.sln.DotSettings = osu.sln.DotSettings
 		osu.TestProject.props = osu.TestProject.props
 	EndProjectSection