Fixed unnecessary zero-length array allocations

Changed all currently present zero-length array allocations in the codebase to use `Array.Empty` instead.

OpenRA.Game/Graphics/HardwarePalette.cs

@@ -24,8 +24,8 @@ namespace OpenRA.Graphics
 		readonly Dictionary<string, ImmutablePalette> palettes = new Dictionary<string, ImmutablePalette>();
 		readonly Dictionary<string, MutablePalette> mutablePalettes = new Dictionary<string, MutablePalette>();
 		readonly Dictionary<string, int> indices = new Dictionary<string, int>();
-		byte[] buffer = new byte[0];
-		float[] colorShiftBuffer = new float[0];
+		byte[] buffer = Array.Empty<byte>();
+		float[] colorShiftBuffer = Array.Empty<float>();
 
 		public HardwarePalette()
 		{

OpenRA.Game/Graphics/SpriteRenderable.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using OpenRA.Primitives;
 
@@ -16,7 +17,7 @@ namespace OpenRA.Graphics
 {
 	public class SpriteRenderable : IPalettedRenderable, IModifyableRenderable, IFinalizedRenderable
 	{
-		public static readonly IEnumerable<IRenderable> None = new IRenderable[0];
+		public static readonly IEnumerable<IRenderable> None = Array.Empty<IRenderable>();
 
 		readonly Sprite sprite;
 		readonly WPos pos;

OpenRA.Game/Map/MapPreview.cs

@@ -370,11 +370,11 @@ namespace OpenRA
 					newData.SpawnPoints = spawns.ToArray();
 				}
 				else
-					newData.SpawnPoints = new CPos[0];
+					newData.SpawnPoints = Array.Empty<CPos>();
 			}
 			catch (Exception)
 			{
-				newData.SpawnPoints = new CPos[0];
+				newData.SpawnPoints = Array.Empty<CPos>();
 				newData.Status = MapStatus.Unavailable;
 			}
 

OpenRA.Game/Primitives/TypeDictionary.cs

@@ -77,7 +77,7 @@ namespace OpenRA.Primitives
 		{
 			if (data.TryGetValue(typeof(T), out var objs))
 				return objs.Cast<T>();
-			return new T[0];
+			return Array.Empty<T>();
 		}
 
 		public void Remove<T>(T val)

OpenRA.Game/Scripting/ScriptContext.cs

@@ -279,7 +279,7 @@ namespace OpenRA.Scripting
 			return outer.SelectMany(i => i.GetGenericArguments());
 		}
 
-		static readonly object[] NoArguments = new object[0];
+		static readonly object[] NoArguments = Array.Empty<object>();
 		Type[] FilterActorCommands(ActorInfo ai)
 		{
 			return FilterCommands(ai, knownActorCommands);

OpenRA.Game/StreamExts.cs

@@ -229,7 +229,7 @@ namespace OpenRA
 			if (!string.IsNullOrEmpty(text))
 				bytes = encoding.GetBytes(text);
 			else
-				bytes = new byte[0];
+				bytes = Array.Empty<byte>();
 
 			s.Write(bytes.Length);
 			s.WriteArray(bytes);

OpenRA.Game/Traits/Player/FrozenActorLayer.cs

@@ -72,8 +72,8 @@ namespace OpenRA.Traits
 
 		public Polygon MouseBounds = Polygon.Empty;
 
-		static readonly IRenderable[] NoRenderables = new IRenderable[0];
-		static readonly Rectangle[] NoBounds = new Rectangle[0];
+		static readonly IRenderable[] NoRenderables = Array.Empty<IRenderable>();
+		static readonly Rectangle[] NoBounds = Array.Empty<Rectangle>();
 
 		int flashTicks;
 		TintModifiers flashModifiers;

OpenRA.Game/Traits/World/ScreenMap.cs

@@ -41,7 +41,7 @@ namespace OpenRA.Traits
 
 	public class ScreenMap : IWorldLoaded
 	{
-		static readonly IEnumerable<FrozenActor> NoFrozenActors = new FrozenActor[0];
+		static readonly IEnumerable<FrozenActor> NoFrozenActors = Array.Empty<FrozenActor>();
 		readonly Func<FrozenActor, bool> frozenActorIsValid = fa => fa.IsValid;
 		readonly Func<Actor, bool> actorIsInWorld = a => a.IsInWorld;
 		readonly Func<Actor, ActorBoundsPair> selectActorAndBounds;

OpenRA.Game/World.cs

@@ -51,7 +51,7 @@ namespace OpenRA
 		public LongBitSet<PlayerBitMask> AllPlayersMask = default(LongBitSet<PlayerBitMask>);
 		public readonly LongBitSet<PlayerBitMask> NoPlayersMask = default(LongBitSet<PlayerBitMask>);
 
-		public Player[] Players = new Player[0];
+		public Player[] Players = Array.Empty<Player>();
 
 		public event Action<Player> RenderPlayerChanged;
 

OpenRA.Mods.Cnc/Graphics/TeslaZapRenderable.cs

@@ -58,7 +58,7 @@ namespace OpenRA.Mods.Cnc.Graphics
 
 			cachedPos = WPos.Zero;
 			cachedLength = WVec.Zero;
-			cache = new IFinalizedRenderable[] { };
+			cache = Array.Empty<IFinalizedRenderable>();
 		}
 
 		public WPos Pos => pos;

OpenRA.Mods.Cnc/SpriteLoaders/TmpRALoader.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.IO;
 using OpenRA.Graphics;
 using OpenRA.Primitives;
@@ -32,7 +33,7 @@ namespace OpenRA.Mods.Cnc.SpriteLoaders
 				Data = data;
 
 				if (data == null)
-					Data = new byte[0];
+					Data = Array.Empty<byte>();
 				else
 					Size = size;
 			}

OpenRA.Mods.Cnc/SpriteLoaders/TmpTDLoader.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.IO;
 using OpenRA.Graphics;
 using OpenRA.Primitives;
@@ -32,7 +33,7 @@ namespace OpenRA.Mods.Cnc.SpriteLoaders
 				Data = data;
 
 				if (data == null)
-					Data = new byte[0];
+					Data = Array.Empty<byte>();
 				else
 					Size = size;
 			}

OpenRA.Mods.Cnc/SpriteLoaders/TmpTSLoader.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.IO;
 using OpenRA.Graphics;
 using OpenRA.Primitives;
@@ -109,7 +110,7 @@ namespace OpenRA.Mods.Cnc.SpriteLoaders
 					}
 				}
 				else
-					Data = new byte[0];
+					Data = Array.Empty<byte>();
 			}
 		}
 

OpenRA.Mods.Cnc/UtilityCommands/RemapShpCommand.cs

@@ -50,7 +50,7 @@ namespace OpenRA.Mods.Cnc.UtilityCommands
 			Game.ModData = destModData;
 			var destPaletteInfo = destModData.DefaultRules.Actors[SystemActors.Player].TraitInfo<PlayerColorPaletteInfo>();
 			var destRemapIndex = destPaletteInfo.RemapIndex;
-			var shadowIndex = new int[] { };
+			var shadowIndex = Array.Empty<int>();
 
 			// the remap range is always 16 entries, but their location and order changes
 			for (var i = 0; i < 16; i++)

OpenRA.Mods.Common/Activities/Air/Land.cs

@@ -54,7 +54,7 @@ namespace OpenRA.Mods.Common.Activities
 			aircraft = self.Trait<Aircraft>();
 			this.target = target;
 			this.offset = offset;
-			this.clearCells = clearCells ?? new CPos[0];
+			this.clearCells = clearCells ?? Array.Empty<CPos>();
 			this.landRange = landRange.Length >= 0 ? landRange : aircraft.Info.LandRange;
 			this.targetLineColor = targetLineColor;
 

OpenRA.Mods.Common/Effects/SpawnActorEffect.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using OpenRA.Activities;
 using OpenRA.Effects;
@@ -26,10 +27,10 @@ namespace OpenRA.Mods.Common.Effects
 		int remainingDelay;
 
 		public SpawnActorEffect(Actor actor)
-			: this(actor, 0, new CPos[0], null) { }
+			: this(actor, 0, Array.Empty<CPos>(), null) { }
 
 		public SpawnActorEffect(Actor actor, int delay)
-			: this(actor, delay, new CPos[0], null) { }
+			: this(actor, delay, Array.Empty<CPos>(), null) { }
 
 		public SpawnActorEffect(Actor actor, int delay, CPos[] pathAfterSpawn, Activity activityAtDestination)
 		{

OpenRA.Mods.Common/SpriteLoaders/TgaLoader.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -78,7 +79,7 @@ namespace OpenRA.Mods.Common.SpriteLoaders
 
 			public TgaFrame()
 			{
-				Data = new byte[0];
+				Data = Array.Empty<byte>();
 			}
 
 			public TgaFrame(Stream stream)

OpenRA.Mods.Common/Traits/Buildings/LineBuild.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using OpenRA.Traits;
@@ -27,7 +28,7 @@ namespace OpenRA.Mods.Common.Traits
 		readonly Actor[] parents = null;
 
 		public LineBuildParentInit(Actor[] value)
-			: base(new string[0])
+			: base(Array.Empty<string>())
 		{
 			parents = value;
 		}
@@ -70,7 +71,7 @@ namespace OpenRA.Mods.Common.Traits
 	public class LineBuild : INotifyKilled, INotifyAddedToWorld, INotifyRemovedFromWorld, INotifyLineBuildSegmentsChanged
 	{
 		readonly LineBuildInfo info;
-		readonly Actor[] parentNodes = new Actor[0];
+		readonly Actor[] parentNodes = Array.Empty<Actor>();
 		HashSet<Actor> segments;
 
 		public LineBuild(ActorInitializer init, LineBuildInfo info)

OpenRA.Mods.Common/Traits/Immobile.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using OpenRA.Traits;
 
@@ -46,7 +47,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (info.OccupiesSpace)
 				occupied = new[] { (TopLeft, SubCell.FullCell) };
 			else
-				occupied = new (CPos, SubCell)[0];
+				occupied = Array.Empty<(CPos, SubCell)>();
 		}
 
 		public CPos TopLeft => location;

OpenRA.Mods.Common/Traits/Targetable.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Linq;
 using OpenRA.Primitives;
 using OpenRA.Traits;
@@ -29,7 +30,7 @@ namespace OpenRA.Mods.Common.Traits
 
 	public class Targetable : ConditionalTrait<TargetableInfo>, ITargetable
 	{
-		protected static readonly string[] None = new string[] { };
+		protected static readonly string[] None = Array.Empty<string>();
 		protected Cloak[] cloaks;
 
 		public Targetable(Actor self, TargetableInfo info)

OpenRA.Mods.Common/UtilityCommands/ConvertSpriteToPngCommand.cs

@@ -35,7 +35,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 			var modData = Game.ModData = utility.ModData;
 
 			var src = args[1];
-			var shadowIndex = new int[] { };
+			var shadowIndex = Array.Empty<int>();
 			if (args.Contains("--noshadow"))
 			{
 				Array.Resize(ref shadowIndex, shadowIndex.Length + 3);

OpenRA.Mods.Common/UtilityCommands/CreateManPage.cs

@@ -38,7 +38,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 			Console.WriteLine(".SH OPTIONS");
 
 			var sections = Game.Settings.Sections;
-			sections.Add("Launch", new LaunchArguments(new Arguments(new string[0])));
+			sections.Add("Launch", new LaunchArguments(new Arguments(Array.Empty<string>())));
 			foreach (var section in sections.OrderBy(s => s.Key))
 			{
 				var fields = section.Value.GetType().GetFields();

OpenRA.Mods.Common/UtilityCommands/DumpSequenceSheetsCommand.cs

@@ -32,7 +32,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 			// HACK: The engine code assumes that Game.modData is set.
 			var modData = Game.ModData = utility.ModData;
 
-			var palette = new ImmutablePalette(args[1], new[] { 0 }, new int[0]);
+			var palette = new ImmutablePalette(args[1], new[] { 0 }, Array.Empty<int>());
 
 			SequenceProvider sequences = null;
 			var mapPackage = new Folder(Platform.EngineDir).OpenPackage(args[2], modData.ModFiles);

OpenRA.Mods.Common/Warheads/FireClusterWarhead.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using OpenRA.GameRules;
@@ -80,8 +81,8 @@ namespace OpenRA.Mods.Common.Warheads
 				CurrentMuzzleFacing = () => (map.CenterOfCell(targetCell) - target.CenterPosition).Yaw,
 
 				DamageModifiers = args.DamageModifiers,
-				InaccuracyModifiers = new int[0],
-				RangeModifiers = new int[0],
+				InaccuracyModifiers = Array.Empty<int>(),
+				RangeModifiers = Array.Empty<int>(),
 
 				Source = target.CenterPosition,
 				CurrentSource = () => target.CenterPosition,

OpenRA.Mods.Common/Widgets/ActorPreviewWidget.cs

@@ -26,7 +26,7 @@ namespace OpenRA.Mods.Common.Widgets
 
 		readonly WorldRenderer worldRenderer;
 
-		IActorPreview[] preview = new IActorPreview[0];
+		IActorPreview[] preview = Array.Empty<IActorPreview>();
 		public int2 PreviewOffset { get; private set; }
 		public int2 IdealPreviewSize { get; private set; }
 

OpenRA.Mods.Common/Widgets/Logic/Ingame/CommandBarLogic.cs

@@ -39,7 +39,7 @@ namespace OpenRA.Mods.Common.Widgets
 		int scatterHighlighted;
 		int stopHighlighted;
 
-		TraitPair<IIssueDeployOrder>[] selectedDeploys = { };
+		TraitPair<IIssueDeployOrder>[] selectedDeploys = Array.Empty<TraitPair<IIssueDeployOrder>>();
 
 		[ObjectCreator.UseCtor]
 		public CommandBarLogic(Widget widget, World world, Dictionary<string, MiniYaml> logicArgs)

OpenRA.Mods.Common/Widgets/Logic/Ingame/StanceSelectorLogic.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Linq;
 using OpenRA.Mods.Common.Traits;
 using OpenRA.Widgets;
@@ -20,7 +21,7 @@ namespace OpenRA.Mods.Common.Widgets
 		readonly World world;
 
 		int selectionHash;
-		TraitPair<AutoTarget>[] actorStances = { };
+		TraitPair<AutoTarget>[] actorStances = Array.Empty<TraitPair<AutoTarget>>();
 
 		[ObjectCreator.UseCtor]
 		public StanceSelectorLogic(Widget widget, World world)

OpenRA.Utility/Program.cs

@@ -68,7 +68,7 @@ namespace OpenRA
 
 			if (args.Length == 0)
 			{
-				PrintUsage(new InstalledMods(modSearchPaths, new string[0]), null);
+				PrintUsage(new InstalledMods(modSearchPaths, Array.Empty<string>()), null);
 				return;
 			}