Remove our own impl of ReadOnlyList and update usages

OpenRA.Game/GameRules/Ruleset.cs

@@ -115,7 +115,7 @@ namespace OpenRA
 			if (filterNode != null)
 				yamlNodes = yamlNodes.Where(k => !filterNode(k));
 
-			return new Dictionary<string, T>(yamlNodes.ToDictionaryWithConflictLog(k => k.Key.ToLowerInvariant(), makeObject, "LoadFromManifest<" + name + ">"));
+			return yamlNodes.ToDictionaryWithConflictLog(k => k.Key.ToLowerInvariant(), makeObject, "LoadFromManifest<" + name + ">");
 		}
 
 		public static Ruleset LoadDefaults(ModData modData)

OpenRA.Game/Graphics/HardwarePalette.cs

@@ -21,14 +21,12 @@ namespace OpenRA.Graphics
 		public int Height { get; private set; }
 		readonly Dictionary<string, ImmutablePalette> palettes = new Dictionary<string, ImmutablePalette>();
 		readonly Dictionary<string, MutablePalette> modifiablePalettes = new Dictionary<string, MutablePalette>();
-		readonly IReadOnlyDictionary<string, MutablePalette> readOnlyModifiablePalettes;
 		readonly Dictionary<string, int> indices = new Dictionary<string, int>();
 		byte[] buffer = new byte[0];
 
 		public HardwarePalette()
 		{
 			Texture = Game.Renderer.Context.CreateTexture();
-			readOnlyModifiablePalettes = modifiablePalettes;
 		}
 
 		public bool Contains(string name)
@@ -109,7 +107,7 @@ namespace OpenRA.Graphics
 		public void ApplyModifiers(IEnumerable<IPaletteModifier> paletteMods)
 		{
 			foreach (var mod in paletteMods)
-				mod.AdjustPalette(readOnlyModifiablePalettes);
+				mod.AdjustPalette(modifiablePalettes);
 
 			// Update our texture with the changes.
 			CopyModifiablePalettesToBuffer();

OpenRA.Game/Manifest.cs

@@ -216,8 +216,7 @@ namespace OpenRA
 			if (!yaml.ContainsKey(key))
 				return new Dictionary<string, string>();
 
-			var inner = yaml[key].ToDictionary(my => my.Value);
-			return inner;
+			return yaml[key].ToDictionary(my => my.Value);
 		}
 
 		public bool Contains<T>() where T : IGlobalModData

OpenRA.Game/Network/OrderManager.cs

@@ -52,7 +52,7 @@ namespace OpenRA.Network
 
 		readonly List<ChatLine> chatCache = new List<ChatLine>();
 
-		public readonly ReadOnlyList<ChatLine> ChatCache;
+		public IReadOnlyList<ChatLine> ChatCache => chatCache;
 
 		bool disposed;
 		bool generateSyncReport = false;
@@ -85,7 +85,6 @@ namespace OpenRA.Network
 			Password = password;
 			Connection = conn;
 			syncReport = new SyncReport(this);
-			ChatCache = new ReadOnlyList<ChatLine>(chatCache);
 			AddChatLine += CacheChatLine;
 		}
 

OpenRA.Game/Primitives/ReadOnlyList.cs

@@ -1,81 +0,0 @@
-#region Copyright & License Information
-/*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
- * This file is part of OpenRA, which is free software. It is made
- * available to you under the terms of the GNU General Public License
- * as published by the Free Software Foundation, either version 3 of
- * the License, or (at your option) any later version. For more
- * information, see COPYING.
- */
-#endregion
-
-using System;
-using System.Collections.Generic;
-
-namespace OpenRA
-{
-	/// <summary>
-	/// A minimal read only list interface for .NET 4
-	/// </summary>
-	/// <remarks>
-	/// .NET 4.5 has an implementation built-in, this code is not meant to
-	/// duplicate it but provide a compatible interface that can be replaced
-	/// when we switch to .NET 4.5 or higher.
-	/// </remarks>
-	public interface IReadOnlyList<out T> : IEnumerable<T>
-	{
-		int Count { get; }
-		T this[int index] { get; }
-	}
-
-	public static class ReadOnlyList
-	{
-		public static IReadOnlyList<T> AsReadOnly<T>(this IList<T> list)
-		{
-			return list as IReadOnlyList<T> ?? new ReadOnlyList<T>(list);
-		}
-	}
-
-	/// <summary>
-	/// A minimal read only list for .NET 4 implemented as a wrapper
-	/// around an IList.
-	/// </summary>
-	public class ReadOnlyList<T> : IReadOnlyList<T>
-	{
-		private readonly IList<T> list;
-
-		public ReadOnlyList()
-			: this(new List<T>())
-		{
-		}
-
-		public ReadOnlyList(IList<T> list)
-		{
-			if (list == null)
-				throw new ArgumentNullException(nameof(list));
-
-			this.list = list;
-		}
-
-		#region IEnumerable implementation
-		public IEnumerator<T> GetEnumerator()
-		{
-			return list.GetEnumerator();
-		}
-		#endregion
-
-		#region IEnumerable implementation
-		System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
-		{
-			return list.GetEnumerator();
-		}
-		#endregion
-
-		#region IReadOnlyList implementation
-		public int Count => list.Count;
-
-		public T this[int index] => list[index];
-
-		#endregion
-	}
-}