Handle yield return base class hoisting calls

Handle new Mono foreach patterns

ICSharpCode.Decompiler/Ast/Transforms/DelegateConstruction.cs

@@ -132,8 +132,8 @@ bool HandleAnonymousMethod(ObjectCreateExpression objectCreateExpression, Expres
 			// Anonymous methods are defined in the same assembly
 			MethodDefinition method = methodRef.ResolveWithinSameModule();
 			if (!IsAnonymousMethod(context, method))
-				return false;
-			
+				return false; 
+
 			// Create AnonymousMethodExpression and prepare parameters
 			AnonymousMethodExpression ame = new AnonymousMethodExpression();
 			ame.CopyAnnotationsFrom(objectCreateExpression); // copy ILRanges etc.
@@ -179,7 +179,7 @@ bool HandleAnonymousMethod(ObjectCreateExpression objectCreateExpression, Expres
 			// Replace all occurrences of 'this' in the method body with the delegate's target:
 			foreach (AstNode node in body.Descendants) {
 				if (node is ThisReferenceExpression)
-					node.ReplaceWith(target.Clone());
+					node.ReplaceWith(target.Clone()); 
 			}
 			Expression replacement;
 			if (isLambda) {
@@ -227,6 +227,42 @@ public override object VisitInvocationExpression(InvocationExpression invocation
 					return converted.AcceptVisitor(this, data);
 				}
 			}
+			var definition = invocationExpression.Annotation<MethodDefinition>();
+			if(definition != null)
+			{
+				//Handle hoisted base calls from yield return compiler generated class (can be generated by both Mono and Roslyn)
+				if (definition.DeclaringType == context.CurrentType && definition.IsCompilerGenerated())
+				{
+					DecompilerContext subContext = context.Clone();
+					subContext.CurrentMethod = definition;
+					subContext.CurrentMethodIsAsync = false;
+					subContext.ReservedVariableNames.AddRange(currentlyUsedVariableNames);
+					var parameters = AstBuilder.MakeParameters(definition, isLambda: true);
+					BlockStatement body = AstMethodBodyBuilder.CreateMethodBody(definition, subContext, parameters);
+					TransformationPipeline.RunTransformationsUntil(body, v => v is DelegateConstruction, subContext);
+
+					if (body.Statements.Count == 1)
+					{
+						var statement = body.Statements.Single();
+						Expression expr = null;
+						if (statement is ReturnStatement)
+						{
+							expr = ((ReturnStatement)statement).Expression;
+						}
+						else  if (statement is ExpressionStatement)
+						{
+							expr = ((ExpressionStatement)statement).Expression;
+						}
+						if (expr != null)
+						{
+							expr.Remove();
+							invocationExpression.ReplaceWith(expr);
+							return expr.AcceptVisitor(this, data);
+						}
+					}
+
+				}
+			}
 			return base.VisitInvocationExpression(invocationExpression, data);
 		}
 

ICSharpCode.Decompiler/Ast/Transforms/PatternStatementTransform.cs

@@ -404,7 +404,9 @@ bool HasAssignment(AstNode root, string variableName)
 						new AssignmentExpression {
 							Left = new IdentifierExpression(Pattern.AnyString).WithName("itemVariable"),
 							Operator = AssignmentOperatorType.Assign,
-							Right = new IdentifierExpressionBackreference("enumeratorVariable").ToExpression().Member("Current")
+							Right =new Choice() { new IdentifierExpressionBackreference("enumeratorVariable").ToExpression().Member("Current"),
+											new IdentifierExpressionBackreference("enumeratorVariable").ToExpression().Member("Current").CastTo(new AnyNode()) //The cast matches Mono non-generic foreaches (which also don't match the non-generic foreach pattern)
+									}	
 						},
 						new Repeat(new AnyNode("statement")).ToStatement()
 					}
@@ -413,6 +415,7 @@ bool HasAssignment(AstNode root, string variableName)
 
 		public ForeachStatement TransformForeach(UsingStatement node)
 		{
+			//return null;
 			Match m = genericForeachPattern.Match(node);
 			if (!m.Success)
 				return null;
@@ -427,17 +430,26 @@ public ForeachStatement TransformForeach(UsingStatement node)
 			// Find the declaration of the item variable:
 			// Because we look only outside the loop, we won't make the mistake of moving a captured variable across the loop boundary
 			VariableDeclarationStatement itemVarDecl = FindVariableDeclaration(loop, itemVar.Identifier);
-			if (itemVarDecl == null || !(itemVarDecl.Parent is BlockStatement))
-				return null;
-
-			// Now verify that we can move the variable declaration in front of the loop:
-			Statement declarationPoint;
-			CanMoveVariableDeclarationIntoStatement(itemVarDecl, loop, out declarationPoint);
-			// We ignore the return value because we don't care whether we can move the variable into the loop
-			// (that is possible only with non-captured variables).
-			// We just care that we can move it in front of the loop:
-			if (declarationPoint != loop)
-				return null;
+			if (itemVarDecl != null)
+			{
+				if (!(itemVarDecl.Parent is BlockStatement))
+					return null;
+
+				// Now verify that we can move the variable declaration in front of the loop:
+				Statement declarationPoint;
+				CanMoveVariableDeclarationIntoStatement(itemVarDecl, loop, out declarationPoint);
+				// We ignore the return value because we don't care whether we can move the variable into the loop
+				// (that is possible only with non-captured variables).
+				// We just care that we can move it in front of the loop:
+				if (declarationPoint != loop)
+					return null;
+			}
+			else //It's okay for the variable declaration to be inside the loop (there should probably be some verification that it's at the beginning of it, though)
+			{
+				itemVarDecl = FindVariableDeclaration(itemVar, itemVar.Identifier);
+				if (itemVarDecl == null)
+					return null;
+			}
 
 			// Make sure that the enumerator variable is not used inside the body
 			var enumeratorId = Identifier.Create(enumeratorVar.Name);
@@ -447,7 +459,7 @@ public ForeachStatement TransformForeach(UsingStatement node)
 			}
 
 			BlockStatement newBody = new BlockStatement();
-			foreach (Statement stmt in m.Get<Statement>("variablesInsideLoop"))
+			foreach (Statement stmt in m.Get<Statement>("variablesInsideLoop").Except(new[] {itemVarDecl}))
 				newBody.Add(stmt.Detach());
 			foreach (Statement stmt in m.Get<Statement>("statement"))
 				newBody.Add(stmt.Detach());