Improved handling of nested display classes.

ICSharpCode.Decompiler/Ast/Transforms/DelegateConstruction.cs

@@ -296,10 +296,10 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 				// Delete the variable declaration statement:
 				AstNode cur = stmt.NextSibling;
 				stmt.Remove();
-				if (blockStatement.Parent.NodeType == NodeType.Member || blockStatement.Parent is Accessor) {
+				
 				// Delete any following statements as long as they assign parameters to the display class
-					// Do parameter handling only for closures created in the top scope (direct child of method/accessor)
+				BlockStatement rootBlock = blockStatement.Ancestors.OfType<BlockStatement>().LastOrDefault() ?? blockStatement;
-					List<ILVariable> parameterOccurrances = blockStatement.Descendants.OfType<IdentifierExpression>()
+				List<ILVariable> parameterOccurrances = rootBlock.Descendants.OfType<IdentifierExpression>()
 					.Select(n => n.Annotation<ILVariable>()).Where(p => p != null && p.IsParameter).ToList();
 				AstNode next;
 				for (; cur != null; cur = next) {
@@ -315,17 +315,22 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 					);
 					Match m = closureFieldAssignmentPattern.Match(cur);
 					if (m != null) {
+						FieldDefinition fieldDef = m.Get<MemberReferenceExpression>("left").Single().Annotation<FieldReference>().ResolveWithinSameModule();
 						AstNode right = m.Get("right").Single();
 						bool isParameter = false;
+						bool isDisplayClassParentPointerAssignment = false;
 						if (right is ThisReferenceExpression) {
 							isParameter = true;
 						} else if (right is IdentifierExpression) {
 							// handle parameters only if the whole method contains no other occurrance except for 'right'
-								ILVariable param = right.Annotation<ILVariable>();
+							ILVariable v = right.Annotation<ILVariable>();
-								isParameter = param.IsParameter && parameterOccurrances.Count(c => c == param) == 1;
+							isParameter = v.IsParameter && parameterOccurrances.Count(c => c == v) == 1;
+							if (!isParameter && TypeAnalysis.IsSameType(v.Type, fieldDef.FieldType) && IsPotentialClosure(context, v.Type.ResolveWithinSameModule())) {
+								isDisplayClassParentPointerAssignment = true;
+							}
 						}
-							if (isParameter) {
+						if (isParameter || isDisplayClassParentPointerAssignment) {
-								dict[m.Get<MemberReferenceExpression>("left").Single().Annotation<FieldReference>().ResolveWithinSameModule()] = right;
+							dict[fieldDef] = right;
 							cur.Remove();
 						} else {
 							break;
@@ -334,12 +339,11 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 						break;
 					}
 				}
-				}
 				
 				// Now create variables for all fields of the display class (except for those that we already handled as parameters)
 				List<Tuple<AstType, string>> variablesToDeclare = new List<Tuple<AstType, string>>();
 				foreach (FieldDefinition field in type.Fields) {
-					if (dict.ContainsKey(field))
+					if (dict.ContainsKey(field)) // skip field if it already was handled as parameter
 						continue;
 					EnsureVariableNameIsAvailable(blockStatement, field.Name);
 					currentlyUsedVariableNames.Add(field.Name);

ICSharpCode.Decompiler/Ast/Transforms/PatternStatementTransform.cs

@@ -299,6 +299,8 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 				InExpression = m.Get<Expression>("collection").Single().Detach(),
 				EmbeddedStatement = newBody
 			};
+			if (foreachStatement.InExpression is BaseReferenceExpression)
+				foreachStatement.InExpression = new ThisReferenceExpression();
 			node.ReplaceWith(foreachStatement);
 			foreach (Statement stmt in m.Get<Statement>("variablesOutsideLoop")) {
 				((BlockStatement)foreachStatement.Parent).Statements.InsertAfter(null, stmt.Detach());

ICSharpCode.Decompiler/Tests/DelegateConstruction.cs

@@ -3,9 +3,48 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 
 public static class DelegateConstruction
 {
+	class InstanceTests
+	{
+		public Action CaptureOfThis()
+		{
+			return delegate {
+				CaptureOfThis();
+			};
+		}
+		
+		public Action CaptureOfThisAndParameter(int a)
+		{
+			return delegate {
+				CaptureOfThisAndParameter(a);
+			};
+		}
+		
+		public Action CaptureOfThisAndParameterInForEach(int a)
+		{
+			foreach (var item in Enumerable.Empty<int>()) {
+				return delegate {
+					CaptureOfThisAndParameter(item + a);
+				};
+			}
+			return null;
+		}
+		
+		public Action CaptureOfThisAndParameterInForEachWithItemCopy(int a)
+		{
+			foreach (var item in Enumerable.Empty<int>()) {
+				int copyOfItem = item;
+				return delegate {
+					CaptureOfThisAndParameter(item + a + copyOfItem);
+				};
+			}
+			return null;
+		}
+	}
+
 	public static void Test(this string a)
 	{
 	}