Fix decompilation of yield return in local functions.

ICSharpCode.Decompiler.Tests/TestCases/Pretty/LocalFunctions.cs

@@ -273,6 +273,19 @@ namespace LocalFunctions
 				}
 			});
 		}
+
+		public static IEnumerable<int> YieldReturn(int n)
+		{
+			return GetNumbers();
+
+			IEnumerable<int> GetNumbers()
+			{
+				for (int i = 0; i < n; i++) {
+					yield return i;
+				}
+			}
+		}
+
 		//public static void LocalFunctionInUsing()
 		//{
 		//	using (MemoryStream memoryStream = new MemoryStream()) {

ICSharpCode.Decompiler/IL/ControlFlow/YieldReturnDecompiler.cs

@@ -338,7 +338,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 		public static bool IsCompilerGeneratorEnumerator(TypeDefinitionHandle type, MetadataReader metadata)
 		{
 			TypeDefinition td;
-			if (type.IsNil || !type.IsCompilerGenerated(metadata) || (td = metadata.GetTypeDefinition(type)).GetDeclaringType().IsNil)
+			if (type.IsNil || !type.IsCompilerGeneratedOrIsInCompilerGeneratedClass(metadata) || (td = metadata.GetTypeDefinition(type)).GetDeclaringType().IsNil)
 				return false;
 			foreach (var i in td.GetInterfaceImplementations()) {
 				var tr = metadata.GetInterfaceImplementation(i).Interface.GetFullTypeName(metadata);

ICSharpCode.Decompiler/SRMExtensions.cs

@@ -309,6 +309,17 @@ namespace ICSharpCode.Decompiler
 			return false;
 		}
 
+		public static bool IsCompilerGeneratedOrIsInCompilerGeneratedClass(this TypeDefinitionHandle handle, MetadataReader metadata)
+		{
+			TypeDefinition type = metadata.GetTypeDefinition(handle);
+			if (type.IsCompilerGenerated(metadata))
+				return true;
+			TypeDefinitionHandle declaringTypeHandle = type.GetDeclaringType();
+			if (!declaringTypeHandle.IsNil && declaringTypeHandle.IsCompilerGenerated(metadata))
+				return true;
+			return false;
+		}
+
 		public static bool IsCompilerGenerated(this MethodDefinition method, MetadataReader metadata)
 		{
 			return method.GetCustomAttributes().HasKnownAttribute(metadata, KnownAttribute.CompilerGenerated);