Fix CA1825 warnings on empty array initialisation.

OpenRA.Game/Map/Map.cs

@@ -270,7 +270,7 @@ namespace OpenRA
 
 				// Take the SHA1
 				if (streams.Count == 0)
-					return CryptoUtil.SHA1Hash(new byte[0]);
+					return CryptoUtil.SHA1Hash(Array.Empty<byte>());
 
 				var merged = streams[0];
 				for (var i = 1; i < streams.Count; i++)
@@ -471,7 +471,7 @@ namespace OpenRA
 			foreach (var cell in AllCells)
 			{
 				var uv = cell.ToMPos(Grid.Type);
-				cellProjection[uv] = new PPos[0];
+				cellProjection[uv] = Array.Empty<PPos>();
 				inverseCellProjection[uv] = new List<MPos>(1);
 			}
 
@@ -973,7 +973,7 @@ namespace OpenRA
 			return (PPos)CellContaining(projectedPos).ToMPos(Grid.Type);
 		}
 
-		static readonly PPos[] NoProjectedCells = { };
+		static readonly PPos[] NoProjectedCells = Array.Empty<PPos>();
 		public PPos[] ProjectedCellsCovering(MPos uv)
 		{
 			if (!initializedCellProjection)

OpenRA.Game/Map/MapPreview.cs

@@ -54,7 +54,7 @@ namespace OpenRA
 		public readonly string[] categories;
 		public readonly int players;
 		public readonly Rectangle bounds;
-		public readonly short[] spawnpoints = { };
+		public readonly short[] spawnpoints = Array.Empty<short>();
 		public readonly MapGridType map_grid_type;
 		public readonly string minimap;
 		public readonly bool downloading;
@@ -160,7 +160,7 @@ namespace OpenRA
 			}
 		}
 
-		static readonly CPos[] NoSpawns = { };
+		static readonly CPos[] NoSpawns = Array.Empty<CPos>();
 		readonly MapCache cache;
 		readonly ModData modData;
 

OpenRA.Game/Map/PlayerReference.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using OpenRA.Primitives;
 
 namespace OpenRA
@@ -53,8 +54,8 @@ namespace OpenRA
 		public bool LockHandicap = false;
 		public int Handicap = 0;
 
-		public string[] Allies = { };
-		public string[] Enemies = { };
+		public string[] Allies = Array.Empty<string>();
+		public string[] Enemies = Array.Empty<string>();
 
 		public PlayerReference() { }
 		public PlayerReference(MiniYaml my) { FieldLoader.Load(this, my); }