Rewrite sequence linting / missing file handling.

- Distinguish between missing sequences and missing sprites
- Lint default sequences as well as maps
- Improved performance
- Correctly handle null images

OpenRA.Game/Graphics/SequenceProvider.cs

@@ -41,7 +41,6 @@ namespace OpenRA.Graphics
 
 	public interface ISpriteSequenceLoader
 	{
-		Action<string> OnMissingSpriteError { get; set; }
 		IReadOnlyDictionary<string, ISpriteSequence> ParseSequences(ModData modData, TileSet tileSet, SpriteCache cache, MiniYamlNode node);
 	}
 
@@ -79,6 +78,8 @@ namespace OpenRA.Graphics
 			return seq;
 		}
 
+		public IEnumerable<string> Images { get { return sequences.Value.Keys; } }
+
 		public bool HasSequence(string unitName)
 		{
 			return sequences.Value.ContainsKey(unitName);
@@ -104,10 +105,11 @@ namespace OpenRA.Graphics
 		{
 			var nodes = MiniYaml.Load(fileSystem, modData.Manifest.Sequences, additionalSequences);
 			var items = new Dictionary<string, UnitSequences>();
-			foreach (var n in nodes)
+			foreach (var node in nodes)
 			{
-				// Work around the loop closure issue in older versions of C#
-				var node = n;
+				// Nodes starting with ^ are inheritable but never loaded directly
+				if (node.Key.StartsWith(ActorInfo.AbstractActorPrefix, StringComparison.Ordinal))
+					continue;
 
 				var key = node.Value.ToLines(node.Key).JoinWith("|");
 

OpenRA.Game/ModData.cs

@@ -79,7 +79,6 @@ namespace OpenRA
 				throw new InvalidOperationException("Unable to find a sequence loader for type '{0}'.".F(sequenceFormat.Type));
 
 			SpriteSequenceLoader = (ISpriteSequenceLoader)sequenceCtor.Invoke(new[] { this });
-			SpriteSequenceLoader.OnMissingSpriteError = s => Log.Write("debug", s);
 
 			var modelFormat = Manifest.Get<ModelSequenceFormat>();
 			var modelLoader = ObjectCreator.FindType(modelFormat.Type + "Loader");

OpenRA.Game/Traits/LintAttributes.cs

@@ -31,12 +31,13 @@ namespace OpenRA.Traits
 	{
 		public readonly string ImageReference; // The field name in the same trait info that contains the image name.
 		public readonly bool Prefix;
-		public readonly bool ActorNameFallback;
-		public SequenceReferenceAttribute(string imageReference = null, bool prefix = false, bool actorNameFallback = false)
+		public readonly bool AllowNullImage;
+
+		public SequenceReferenceAttribute(string imageReference = null, bool prefix = false, bool allowNullImage = false)
 		{
 			ImageReference = imageReference;
 			Prefix = prefix;
-			ActorNameFallback = actorNameFallback;
+			AllowNullImage = allowNullImage;
 		}
 	}