Remove our own ReadOnlyDictionary and update usages

OpenRA.Game/Actor.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using Eluant;

OpenRA.Game/ExternalMods.cs

@@ -294,6 +294,11 @@ namespace OpenRA
 		public int Count => mods.Count;
 		public ICollection<string> Keys => mods.Keys;
 		public ICollection<ExternalMod> Values => mods.Values;
+
+		IEnumerable<string> IReadOnlyDictionary<string, ExternalMod>.Keys => ((IReadOnlyDictionary<string, ExternalMod>)mods).Keys;
+
+		IEnumerable<ExternalMod> IReadOnlyDictionary<string, ExternalMod>.Values => ((IReadOnlyDictionary<string, ExternalMod>)mods).Values;
+
 		public bool ContainsKey(string key) { return mods.ContainsKey(key); }
 		public IEnumerator<KeyValuePair<string, ExternalMod>> GetEnumerator() { return mods.GetEnumerator(); }
 		public bool TryGetValue(string key, out ExternalMod value) { return mods.TryGetValue(key, out value); }

OpenRA.Game/GameRules/Ruleset.cs

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

OpenRA.Game/Graphics/ChromeProvider.cs

@@ -52,7 +52,7 @@ namespace OpenRA.Graphics
 			public readonly Dictionary<string, Rectangle> Regions = new Dictionary<string, Rectangle>();
 		}
 
-		public static IReadOnlyDictionary<string, Collection> Collections { get; private set; }
+		public static IReadOnlyDictionary<string, Collection> Collections => collections;
 		static Dictionary<string, Collection> collections;
 		static Dictionary<string, (Sheet Sheet, int Density)> cachedSheets;
 		static Dictionary<string, Dictionary<string, Sprite>> cachedSprites;
@@ -77,8 +77,6 @@ namespace OpenRA.Graphics
 			cachedPanelSprites = new Dictionary<string, Sprite[]>();
 			cachedCollectionSheets = new Dictionary<Collection, (Sheet, int)>();
 
-			Collections = new ReadOnlyDictionary<string, Collection>(collections);
-
 			var chrome = MiniYaml.Merge(modData.Manifest.Chrome
 				.Select(s => MiniYaml.FromStream(fileSystem.Open(s), s)));
 

OpenRA.Game/Graphics/CursorProvider.cs

@@ -38,8 +38,7 @@ namespace OpenRA.Graphics
 			Palettes = nodesDict["Cursors"].Nodes.Select(n => n.Value.Value)
 				.Where(p => p != null)
 				.Distinct()
-				.ToDictionary(p => p, p => pals[p].ReadPalette(modData.DefaultFileSystem))
+				.ToDictionary(p => p, p => pals[p].ReadPalette(modData.DefaultFileSystem));
-				.AsReadOnly();
 
 			var frameCache = new FrameCache(fileSystem, modData.SpriteLoaders);
 			var cursors = new Dictionary<string, CursorSequence>();
@@ -47,7 +46,7 @@ namespace OpenRA.Graphics
 				foreach (var sequence in s.Value.Nodes)
 					cursors.Add(sequence.Key, new CursorSequence(frameCache, sequence.Key, s.Key, s.Value.Value, sequence.Value));
 
-			Cursors = cursors.AsReadOnly();
+			Cursors = cursors;
 		}
 
 		public bool HasCursorSequence(string cursor)

OpenRA.Game/Graphics/HardwarePalette.cs

@@ -28,7 +28,7 @@ namespace OpenRA.Graphics
 		public HardwarePalette()
 		{
 			Texture = Game.Renderer.Context.CreateTexture();
-			readOnlyModifiablePalettes = modifiablePalettes.AsReadOnly();
+			readOnlyModifiablePalettes = modifiablePalettes;
 		}
 
 		public bool Contains(string name)

OpenRA.Game/Graphics/Model.cs

@@ -10,6 +10,7 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
 using OpenRA.FileSystem;
 using OpenRA.Primitives;
 

OpenRA.Game/Graphics/SequenceProvider.cs

@@ -125,7 +125,7 @@ namespace OpenRA.Graphics
 				}
 			}
 
-			return new ReadOnlyDictionary<string, UnitSequences>(items);
+			return items;
 		}
 
 		public void Preload()

OpenRA.Game/InstalledMods.cs

@@ -16,7 +16,6 @@ using System.IO;
 using System.Linq;
 using OpenRA.FileSystem;
 using OpenRA.Graphics;
-using OpenRA.Primitives;
 
 namespace OpenRA
 {
@@ -100,9 +99,9 @@ namespace OpenRA
 		}
 
 		public Manifest this[string key] => mods[key];
+		public IEnumerable<string> Keys => mods.Keys;
+		public IEnumerable<Manifest> Values => mods.Values;
 		public int Count => mods.Count;
-		public ICollection<string> Keys => mods.Keys;
-		public ICollection<Manifest> Values => mods.Values;
 		public bool ContainsKey(string key) { return mods.ContainsKey(key); }
 		public IEnumerator<KeyValuePair<string, Manifest>> GetEnumerator() { return mods.GetEnumerator(); }
 		public bool TryGetValue(string key, out Manifest value) { return mods.TryGetValue(key, out value); }

OpenRA.Game/Manifest.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using OpenRA.FileSystem;
@@ -127,7 +128,7 @@ namespace OpenRA
 			MapFolders = YamlDictionary(yaml, "MapFolders");
 
 			if (yaml.TryGetValue("Packages", out var packages))
-				Packages = packages.ToDictionary(x => x.Value).AsReadOnly();
+				Packages = packages.ToDictionary(x => x.Value);
 
 			Rules = YamlList(yaml, "Rules");
 			Sequences = YamlList(yaml, "Sequences");
@@ -213,10 +214,10 @@ namespace OpenRA
 		static IReadOnlyDictionary<string, string> YamlDictionary(Dictionary<string, MiniYaml> yaml, string key)
 		{
 			if (!yaml.ContainsKey(key))
-				return new ReadOnlyDictionary<string, string>();
+				return new Dictionary<string, string>();
 
 			var inner = yaml[key].ToDictionary(my => my.Value);
-			return new ReadOnlyDictionary<string, string>(inner);
+			return inner;
 		}
 
 		public bool Contains<T>() where T : IGlobalModData

OpenRA.Game/Map/MapCache.cs

@@ -26,7 +26,7 @@ namespace OpenRA
 	public sealed class MapCache : IEnumerable<MapPreview>, IDisposable
 	{
 		public static readonly MapPreview UnknownMap = new MapPreview(null, null, MapGridType.Rectangular, null);
-		public readonly IReadOnlyDictionary<IReadOnlyPackage, MapClassification> MapLocations;
+		public IReadOnlyDictionary<IReadOnlyPackage, MapClassification> MapLocations => mapLocations;
 		readonly Dictionary<IReadOnlyPackage, MapClassification> mapLocations = new Dictionary<IReadOnlyPackage, MapClassification>();
 
 		readonly Cache<string, MapPreview> previews;
@@ -46,8 +46,6 @@ namespace OpenRA
 			var gridType = Exts.Lazy(() => modData.Manifest.Get<MapGrid>().Type);
 			previews = new Cache<string, MapPreview>(uid => new MapPreview(modData, uid, gridType.Value, this));
 			sheetBuilder = new SheetBuilder(SheetType.BGRA);
-
-			MapLocations = new ReadOnlyDictionary<IReadOnlyPackage, MapClassification>(mapLocations);
 		}
 
 		public void LoadMaps()

OpenRA.Game/ModData.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using OpenRA.FileSystem;

OpenRA.Game/Primitives/Cache.cs

@@ -40,6 +40,11 @@ namespace OpenRA.Primitives
 
 		public ICollection<T> Keys => cache.Keys;
 		public ICollection<U> Values => cache.Values;
+
+		IEnumerable<T> IReadOnlyDictionary<T, U>.Keys => cache.Keys;
+
+		IEnumerable<U> IReadOnlyDictionary<T, U>.Values => cache.Values;
+
 		public IEnumerator<KeyValuePair<T, U>> GetEnumerator() { return cache.GetEnumerator(); }
 		System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return GetEnumerator(); }
 	}

OpenRA.Game/Primitives/ConcurrentCache.cs

@@ -12,6 +12,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace OpenRA.Primitives
 {
@@ -33,12 +34,13 @@ namespace OpenRA.Primitives
 			: this(loader, EqualityComparer<T>.Default) { }
 
 		public U this[T key] => cache.GetOrAdd(key, loader);
+		public IEnumerable<T> Keys => cache.Keys;
+
+		public IEnumerable<U> Values => cache.Values;
 
 		public bool ContainsKey(T key) { return cache.ContainsKey(key); }
 		public bool TryGetValue(T key, out U value) { return cache.TryGetValue(key, out value); }
 		public int Count => cache.Count;
-		public ICollection<T> Keys => cache.Keys;
-		public ICollection<U> Values => cache.Values;
 		public IEnumerator<KeyValuePair<T, U>> GetEnumerator() { return cache.GetEnumerator(); }
 		System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return GetEnumerator(); }
 	}

OpenRA.Game/Primitives/PlayerDictionary.cs

@@ -52,10 +52,13 @@ namespace OpenRA.Primitives
 		public T this[int playerIndex] => valueByPlayerIndex[playerIndex];
 
 		public int Count => valueByPlayerIndex.Length;
+
+		public IEnumerable<Player> Keys => ((IReadOnlyDictionary<Player, T>)valueByPlayer).Keys;
+
+		public IEnumerable<T> Values => ((IReadOnlyDictionary<Player, T>)valueByPlayer).Values;
+
 		public IEnumerator<T> GetEnumerator() { return ((IEnumerable<T>)valueByPlayerIndex).GetEnumerator(); }
 
-		ICollection<Player> IReadOnlyDictionary<Player, T>.Keys => valueByPlayer.Keys;
-		ICollection<T> IReadOnlyDictionary<Player, T>.Values => valueByPlayer.Values;
 		bool IReadOnlyDictionary<Player, T>.ContainsKey(Player key) { return valueByPlayer.ContainsKey(key); }
 		bool IReadOnlyDictionary<Player, T>.TryGetValue(Player key, out T value) { return valueByPlayer.TryGetValue(key, out value); }
 		IEnumerator<KeyValuePair<Player, T>> IEnumerable<KeyValuePair<Player, T>>.GetEnumerator() { return valueByPlayer.GetEnumerator(); }

OpenRA.Game/Primitives/ReadOnlyDictionary.cs

@@ -1,100 +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 dictionary 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 IReadOnlyDictionary<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>
-	{
-		int Count { get; }
-		TValue this[TKey key] { get; }
-		ICollection<TKey> Keys { get; }
-		ICollection<TValue> Values { get; }
-
-		bool ContainsKey(TKey key);
-		bool TryGetValue(TKey key, out TValue value);
-	}
-
-	public static class ReadOnlyDictionary
-	{
-		public static IReadOnlyDictionary<TKey, TValue> AsReadOnly<TKey, TValue>(this IDictionary<TKey, TValue> dict)
-		{
-			return dict as IReadOnlyDictionary<TKey, TValue> ?? new ReadOnlyDictionary<TKey, TValue>(dict);
-		}
-	}
-
-	/// <summary>
-	/// A minimal read only dictionary for .NET 4 implemented as a wrapper
-	/// around an IDictionary.
-	/// </summary>
-	public class ReadOnlyDictionary<TKey, TValue> : IReadOnlyDictionary<TKey, TValue>
-	{
-		private readonly IDictionary<TKey, TValue> dict;
-
-		public ReadOnlyDictionary()
-			: this(new Dictionary<TKey, TValue>())
-		{
-		}
-
-		public ReadOnlyDictionary(IDictionary<TKey, TValue> dict)
-		{
-			if (dict == null)
-				throw new ArgumentNullException(nameof(dict));
-
-			this.dict = dict;
-		}
-
-		#region IReadOnlyDictionary implementation
-		public bool ContainsKey(TKey key)
-		{
-			return dict.ContainsKey(key);
-		}
-
-		public bool TryGetValue(TKey key, out TValue value)
-		{
-			return dict.TryGetValue(key, out value);
-		}
-
-		public int Count => dict.Count;
-
-		public TValue this[TKey key] => dict[key];
-
-		public ICollection<TKey> Keys => dict.Keys;
-
-		public ICollection<TValue> Values => dict.Values;
-
-		#endregion
-
-		#region IEnumerable implementation
-		public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
-		{
-			return dict.GetEnumerator();
-		}
-		#endregion
-
-		#region IEnumerable implementation
-		System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
-		{
-			return dict.GetEnumerator();
-		}
-		#endregion
-	}
-}

OpenRA.Game/Renderer.cs

@@ -113,7 +113,7 @@ namespace OpenRA
 				fontSheetBuilder = new SheetBuilder(SheetType.BGRA, 512);
 				Fonts = modData.Manifest.Get<Fonts>().FontList.ToDictionary(x => x.Key,
 					x => new SpriteFont(x.Value.Font, modData.DefaultFileSystem.Open(x.Value.Font).ReadAllBytes(),
-										x.Value.Size, x.Value.Ascender, Window.EffectiveWindowScale, fontSheetBuilder)).AsReadOnly();
+										x.Value.Size, x.Value.Ascender, Window.EffectiveWindowScale, fontSheetBuilder));
 			}
 
 			Window.OnWindowScaleChanged += (oldNative, oldEffective, newNative, newEffective) =>

OpenRA.Game/Support/VariableExpression.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using System.Linq.Expressions;

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Diagnostics.CodeAnalysis;
 using OpenRA.Activities;
 using OpenRA.FileSystem;

OpenRA.Mods.Cnc/FileSystem/MixFile.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using OpenRA.FileSystem;

OpenRA.Mods.Cnc/Traits/PaletteEffects/ChronoshiftPaletteEffect.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System.Collections.Generic;
 using OpenRA.Graphics;
 using OpenRA.Primitives;
 using OpenRA.Traits;

OpenRA.Mods.Cnc/Traits/TDGunboat.cs

@@ -10,6 +10,7 @@
 #endregion
 
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using OpenRA.Activities;
 using OpenRA.Mods.Common;
@@ -42,7 +43,7 @@ namespace OpenRA.Mods.Cnc.Traits
 		public IReadOnlyDictionary<CPos, SubCell> OccupiedCells(ActorInfo info, CPos location, SubCell subCell = SubCell.Any)
 		{
 			var occupied = new Dictionary<CPos, SubCell>() { { location, SubCell.FullCell } };
-			return new ReadOnlyDictionary<CPos, SubCell>(occupied);
+			return occupied;
 		}
 
 		bool IOccupySpaceInfo.SharesCell => false;

OpenRA.Mods.Common/FileFormats/InstallShieldCABCompression.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using ICSharpCode.SharpZipLib.Zip.Compression;

OpenRA.Mods.Common/FileSystem/InstallShieldPackage.cs

@@ -10,6 +10,7 @@
 #endregion
 
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using OpenRA.FileSystem;
 using OpenRA.Mods.Common.FileFormats;

OpenRA.Mods.Common/Graphics/DefaultSpriteSequence.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using OpenRA.Graphics;

OpenRA.Mods.Common/Lint/CheckActorReferences.cs

@@ -10,6 +10,7 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
 using OpenRA.GameRules;

OpenRA.Mods.Common/SpriteLoaders/PngSheetLoader.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using OpenRA.FileFormats;

OpenRA.Mods.Common/Terrain/DefaultTerrain.cs

@@ -115,7 +115,7 @@ namespace OpenRA.Mods.Common.Terrain
 
 			// Templates
 			Templates = yaml["Templates"].ToDictionary().Values
-				.Select(y => (TerrainTemplateInfo)new DefaultTerrainTemplateInfo(this, y)).ToDictionary(t => t.Id).AsReadOnly();
+				.Select(y => (TerrainTemplateInfo)new DefaultTerrainTemplateInfo(this, y)).ToDictionary(t => t.Id);
 		}
 
 		public TerrainTypeInfo this[byte index] => TerrainInfo[index];

OpenRA.Mods.Common/Terrain/TerrainInfo.cs

@@ -9,6 +9,8 @@
  */
 #endregion
 
+using System.Collections.Generic;
+
 namespace OpenRA.Mods.Common.Terrain
 {
 	public interface ITemplatedTerrainInfo : ITerrainInfo

OpenRA.Mods.Common/Traits/Air/Aircraft.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using OpenRA.Activities;
 using OpenRA.Mods.Common.Activities;
@@ -179,7 +180,7 @@ namespace OpenRA.Mods.Common.Traits
 			yield return new FacingInit(PreviewFacing);
 		}
 
-		public IReadOnlyDictionary<CPos, SubCell> OccupiedCells(ActorInfo info, CPos location, SubCell subCell = SubCell.Any) { return new ReadOnlyDictionary<CPos, SubCell>(); }
+		public IReadOnlyDictionary<CPos, SubCell> OccupiedCells(ActorInfo info, CPos location, SubCell subCell = SubCell.Any) { return new Dictionary<CPos, SubCell>(); }
 
 		bool IOccupySpaceInfo.SharesCell => false;
 

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

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using OpenRA.Graphics;
 using OpenRA.Traits;
@@ -241,7 +242,7 @@ namespace OpenRA.Mods.Common.Traits
 			var occupied = OccupiedTiles(topLeft)
 				.ToDictionary(c => c, c => SubCell.FullCell);
 
-			return new ReadOnlyDictionary<CPos, SubCell>(occupied);
+			return occupied;
 		}
 
 		bool IOccupySpaceInfo.SharesCell => false;

OpenRA.Mods.Common/Traits/Crates/Crate.cs

@@ -35,7 +35,7 @@ namespace OpenRA.Mods.Common.Traits
 		public IReadOnlyDictionary<CPos, SubCell> OccupiedCells(ActorInfo info, CPos location, SubCell subCell = SubCell.Any)
 		{
 			var occupied = new Dictionary<CPos, SubCell>() { { location, SubCell.FullCell } };
-			return new ReadOnlyDictionary<CPos, SubCell>(occupied);
+			return occupied;
 		}
 
 		bool IOccupySpaceInfo.SharesCell => false;

OpenRA.Mods.Common/Traits/Harvester.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using OpenRA.Activities;
 using OpenRA.Mods.Common.Activities;

OpenRA.Mods.Common/Traits/Husk.cs

@@ -10,6 +10,7 @@
 #endregion
 
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using OpenRA.Mods.Common.Activities;
 using OpenRA.Primitives;
@@ -37,7 +38,7 @@ namespace OpenRA.Mods.Common.Traits
 		public IReadOnlyDictionary<CPos, SubCell> OccupiedCells(ActorInfo info, CPos location, SubCell subCell = SubCell.Any)
 		{
 			var occupied = new Dictionary<CPos, SubCell>() { { location, SubCell.FullCell } };
-			return new ReadOnlyDictionary<CPos, SubCell>(occupied);
+			return occupied;
 		}
 
 		bool IOccupySpaceInfo.SharesCell => false;

OpenRA.Mods.Common/Traits/Immobile.cs

@@ -10,7 +10,6 @@
 #endregion
 
 using System.Collections.Generic;
-using OpenRA.Primitives;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.Common.Traits
@@ -25,7 +24,7 @@ namespace OpenRA.Mods.Common.Traits
 			var occupied = OccupiesSpace ? new Dictionary<CPos, SubCell>() { { location, SubCell.FullCell } } :
 				new Dictionary<CPos, SubCell>();
 
-			return new ReadOnlyDictionary<CPos, SubCell>(occupied);
+			return occupied;
 		}
 
 		bool IOccupySpaceInfo.SharesCell => false;

OpenRA.Mods.Common/Traits/Mobile.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using OpenRA.Activities;
 using OpenRA.Mods.Common.Activities;
@@ -130,7 +131,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		public IReadOnlyDictionary<CPos, SubCell> OccupiedCells(ActorInfo info, CPos location, SubCell subCell = SubCell.Any)
 		{
-			return new ReadOnlyDictionary<CPos, SubCell>(new Dictionary<CPos, SubCell>() { { location, subCell } });
+			return new Dictionary<CPos, SubCell>() { { location, subCell } };
 		}
 
 		bool IOccupySpaceInfo.SharesCell => LocomotorInfo.SharesCell;

OpenRA.Mods.Common/Traits/PaletteEffects/CloakPaletteEffect.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System.Collections.Generic;
 using OpenRA.Graphics;
 using OpenRA.Primitives;
 using OpenRA.Traits;

OpenRA.Mods.Common/Traits/Player/PlayerResources.cs

@@ -61,7 +61,7 @@ namespace OpenRA.Mods.Common.Traits
 
 			if (startingCash.Any())
 				yield return new LobbyOption("startingcash", DefaultCashDropdownLabel, DefaultCashDropdownDescription, DefaultCashDropdownVisible, DefaultCashDropdownDisplayOrder,
-					new ReadOnlyDictionary<string, string>(startingCash), DefaultCash.ToString(), DefaultCashDropdownLocked);
+					startingCash, DefaultCash.ToString(), DefaultCashDropdownLocked);
 		}
 
 		public override object Create(ActorInitializer init) { return new PlayerResources(init.Self, this); }

OpenRA.Mods.Common/Traits/Player/TimeLimitManager.cs

@@ -84,7 +84,7 @@ namespace OpenRA.Mods.Common.Traits
 			});
 
 			yield return new LobbyOption("timelimit", TimeLimitLabel, TimeLimitDescription, TimeLimitDropdownVisible, TimeLimitDisplayOrder,
-				new ReadOnlyDictionary<string, string>(timelimits), TimeLimitDefault.ToString(), TimeLimitLocked);
+				timelimits, TimeLimitDefault.ToString(), TimeLimitLocked);
 		}
 
 		public override object Create(ActorInitializer init) { return new TimeLimitManager(init.Self, this); }

OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using OpenRA.Graphics;
@@ -80,8 +81,7 @@ namespace OpenRA.Mods.Common.Traits
 				Footprint = ios.OccupiedCells(Info, location, subCell);
 			else
 			{
-				var footprint = new Dictionary<CPos, SubCell>() { { location, SubCell.FullCell } };
+				Footprint = new Dictionary<CPos, SubCell>() { { location, SubCell.FullCell } };
-				Footprint = new ReadOnlyDictionary<CPos, SubCell>(footprint);
 			}
 
 			tooltip = Info.TraitInfos<EditorOnlyTooltipInfo>().FirstOrDefault(info => info.EnabledByDefault) as TooltipInfoBase

OpenRA.Mods.Common/Traits/World/MapOptions.cs

@@ -82,14 +82,14 @@ namespace OpenRA.Mods.Common.Traits
 
 			if (techLevels.Any())
 				yield return new LobbyOption("techlevel", TechLevelDropdownLabel, TechLevelDropdownDescription,	TechLevelDropdownVisible, TechLevelDropdownDisplayOrder,
-					new ReadOnlyDictionary<string, string>(techLevels),	TechLevel, TechLevelDropdownLocked);
+					techLevels,	TechLevel, TechLevelDropdownLocked);
 
 			var gameSpeeds = Game.ModData.Manifest.Get<GameSpeeds>().Speeds
 				.ToDictionary(s => s.Key, s => s.Value.Name);
 
 			// NOTE: The server hardcodes special-case logic for this option id
 			yield return new LobbyOption("gamespeed", GameSpeedDropdownLabel, GameSpeedDropdownDescription, GameSpeedDropdownVisible, GameSpeedDropdownDisplayOrder,
-				new ReadOnlyDictionary<string, string>(gameSpeeds), GameSpeed, GameSpeedDropdownLocked);
+				gameSpeeds, GameSpeed, GameSpeedDropdownLocked);
 		}
 
 		void IRulesetLoaded<ActorInfo>.RulesetLoaded(Ruleset rules, ActorInfo info)

OpenRA.Mods.Common/Traits/World/ScriptLobbyDropdown.cs

@@ -48,7 +48,7 @@ namespace OpenRA.Mods.Common.Traits
 		IEnumerable<LobbyOption> ILobbyOptions.LobbyOptions(Ruleset rules)
 		{
 			yield return new LobbyOption(ID, Label, Description, Visible, DisplayOrder,
-				new ReadOnlyDictionary<string, string>(Values), Default, Locked);
+				Values, Default, Locked);
 		}
 
 		public override object Create(ActorInitializer init) { return new ScriptLobbyDropdown(this); }

OpenRA.Mods.Common/Traits/World/SpawnStartingUnits.cs

@@ -48,7 +48,7 @@ namespace OpenRA.Mods.Common.Traits
 
 			if (startingUnits.Any())
 				yield return new LobbyOption("startingunits", DropdownLabel, DropdownDescription, DropdownVisible, DropdownDisplayOrder,
-					new ReadOnlyDictionary<string, string>(startingUnits), StartingUnitsClass, DropdownLocked);
+					startingUnits, StartingUnitsClass, DropdownLocked);
 		}
 
 		public override object Create(ActorInitializer init) { return new SpawnStartingUnits(this); }

OpenRA.Test/OpenRA.Game/VariableExpressionTest.cs

@@ -10,6 +10,7 @@
 #endregion
 
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using NUnit.Framework;
 using OpenRA.Support;
@@ -19,13 +20,13 @@ namespace OpenRA.Test
 	[TestFixture]
 	public class VariableExpressionTest
 	{
-		IReadOnlyDictionary<string, int> testValues = new ReadOnlyDictionary<string, int>(new Dictionary<string, int>()
+		IReadOnlyDictionary<string, int> testValues = new Dictionary<string, int>
 		{
 			{ "t", 5 },
 			{ "t-1", 7 },
 			{ "one", 1 },
 			{ "five", 5 }
-		});
+		};
 
 		void AssertFalse(string expression)
 		{