Merge NRefactory commit 'a3ced27e3e0515d4192e49318f2d24ec9f11fcd1' into SharpDevelop newNR branch.

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngine.cs

@@ -189,6 +189,29 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 			}
 		}
 
+		IEnumerable<ICompletionData> HandleMemberReferenceCompletion(ExpressionResult expr)
+		{
+			if (expr == null) 
+				return null;
+		
+			// do not complete <number>. (but <number>.<number>.)
+			if (expr.Node is PrimitiveExpression) {
+				var pexpr = (PrimitiveExpression)expr.Node;
+				if (!(pexpr.Value is string || pexpr.Value is char) && !pexpr.LiteralValue.Contains('.')) {
+					return null;
+				}
+			}
+			
+			var resolveResult = ResolveExpression (expr);
+			if (resolveResult == null) {
+				return null;
+			}
+			if (expr.Node is AstType) {
+				return CreateTypeAndNamespaceCompletionData(location, resolveResult.Item1, expr.Node, resolveResult.Item2);
+			}
+			return CreateCompletionData(location, resolveResult.Item1, expr.Node, resolveResult.Item2);
+		}
+
 		IEnumerable<ICompletionData> MagicKeyCompletion(char completionChar, bool controlSpace)
 		{
 			ExpressionResult expr;
@@ -201,26 +224,7 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 					if (IsInsideCommentOrString()) {
 						return Enumerable.Empty<ICompletionData>();
 					}
-					expr = GetExpressionBeforeCursor();
+					return HandleMemberReferenceCompletion(GetExpressionBeforeCursor());
-					if (expr == null) {
-						return null;
-					}
-					// do not complete <number>. (but <number>.<number>.)
-					if (expr.Node is PrimitiveExpression) {
-						var pexpr = (PrimitiveExpression)expr.Node;
-						if (!(pexpr.Value is string || pexpr.Value is char) && !pexpr.LiteralValue.Contains('.')) {
-							return null;
-						}
-					}
-
-					resolveResult = ResolveExpression(expr);
-					if (resolveResult == null) {
-						return null;
-					}
-					if (expr.Node is AstType) {
-						return CreateTypeAndNamespaceCompletionData(location, resolveResult.Item1, expr.Node, resolveResult.Item2);
-					}
-					return CreateCompletionData(location, resolveResult.Item1, expr.Node, resolveResult.Item2);
 				case '#':
 					if (IsInsideCommentOrString()) {
 						return null;
@@ -506,20 +510,32 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 				
 					var contextList = new CompletionDataWrapper (this);
 					var identifierStart = GetExpressionAtCursor();
+					if (identifierStart != null) {
 
-					if (identifierStart != null && identifierStart.Node is TypeParameterDeclaration) {
-						return null;
-					}
-
-					if (identifierStart != null && identifierStart.Node is VariableInitializer && location <= ((VariableInitializer)identifierStart.Node).NameToken.EndLocation) {
-						return controlSpace ? HandleAccessorContext() ?? DefaultControlSpaceItems(identifierStart) : null;
-					}
 						
-					if (identifierStart != null && identifierStart.Node is CatchClause) {
+						if (identifierStart.Node is TypeParameterDeclaration) {
-						if (((CatchClause)identifierStart.Node).VariableNameToken.Contains(location)) {
 							return null;
 						}
-						identifierStart = null;
+
+						if (identifierStart.Node is MemberReferenceExpression) {
+							return HandleMemberReferenceCompletion(new ExpressionResult (((MemberReferenceExpression)identifierStart.Node).Target, identifierStart.Unit));
+						}
+
+						if (identifierStart.Node is Identifier) {
+							// May happen in variable names
+							return controlSpace ? DefaultControlSpaceItems(identifierStart) : null;
+						}
+	
+						if (identifierStart.Node is VariableInitializer && location <= ((VariableInitializer)identifierStart.Node).NameToken.EndLocation) {
+							return controlSpace ? HandleAccessorContext() ?? DefaultControlSpaceItems(identifierStart) : null;
+						}
+	
+						if (identifierStart.Node is CatchClause) {
+							if (((CatchClause)identifierStart.Node).VariableNameToken.Contains(location)) {
+								return null;
+							}
+							identifierStart = null;
+						}
 					}
 					if (!(char.IsLetter(completionChar) || completionChar == '_') && (!controlSpace || identifierStart == null || !(identifierStart.Node.Parent is ArrayInitializerExpression))) {
 						return controlSpace ? HandleAccessorContext() ?? DefaultControlSpaceItems(identifierStart) : null;
@@ -2307,14 +2323,14 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 
 		ExpressionResult GetExpressionAtCursor()
 		{
-//			TextLocation memberLocation;
+			//			TextLocation memberLocation;
-//			if (currentMember != null) {
+			//			if (currentMember != null) {
-//				memberLocation = currentMember.Region.Begin;
+			//				memberLocation = currentMember.Region.Begin;
-//			} else if (currentType != null) {
+			//			} else if (currentType != null) {
-//				memberLocation = currentType.Region.Begin;
+			//				memberLocation = currentType.Region.Begin;
-//			} else {
+			//			} else {
-//				memberLocation = location;
+			//				memberLocation = location;
-//			}
+			//			}
 			var baseUnit = ParseStub("a");
 			
 			var tmpUnit = baseUnit;
@@ -2322,7 +2338,8 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 			if (expr == null) {
 				expr = baseUnit.GetNodeAt<AstType>(location.Line, location.Column - 1);
 			}
-
+			if (expr == null)
+				expr = baseUnit.GetNodeAt<Identifier>(location.Line, location.Column - 1);
 			// try insertStatement
 			if (expr == null && baseUnit.GetNodeAt<EmptyStatement>(location.Line, location.Column) != null) {
 				tmpUnit = baseUnit = ParseStub("a();", false);

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngineBase.cs

@@ -415,9 +415,9 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 				wrapper.Append (';');
 		}
 
-		protected CompilationUnit ParseStub (string continuation, bool appendSemicolon = true, string afterContinuation = null)
+		protected CompilationUnit ParseStub(string continuation, bool appendSemicolon = true, string afterContinuation = null)
 		{
-			var mt = GetMemberTextToCaret ();
+			var mt = GetMemberTextToCaret();
 			if (mt == null) {
 				return null;
 			}
@@ -429,7 +429,7 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 			var wrapper = new StringBuilder ();
 			bool wrapInClass = memberLocation != new TextLocation (1, 1);
 			if (wrapInClass) {
-				var nodeAtLocation = Unit.GetNodeAt (memberLocation, n => n is TypeDeclaration || n is NamespaceDeclaration);
+				var nodeAtLocation = Unit.GetNodeAt(memberLocation, n => n is TypeDeclaration || n is NamespaceDeclaration);
 				if (nodeAtLocation != null) {
 					foreach (var n in nodeAtLocation.AncestorsAndSelf) {
 						if (memberLocation == n.StartLocation) {
@@ -438,25 +438,25 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 						if (n is TypeDeclaration) {
 							var t = (TypeDeclaration)n;
 							switch (t.ClassType) {
-							case ClassType.Class:
+								case ClassType.Class:
-								wrapper.Append ("class");
+									wrapper.Append("class");
-								break;
+									break;
-							case ClassType.Struct:
+								case ClassType.Struct:
-								wrapper.Append ("struct");
+									wrapper.Append("struct");
-								break;
+									break;
-							case ClassType.Interface:
+								case ClassType.Interface:
-								wrapper.Append ("interface");
+									wrapper.Append("interface");
-								break;
+									break;
-							case ClassType.Enum:
+								case ClassType.Enum:
-								wrapper.Append ("enum");
+									wrapper.Append("enum");
-								break;
+									break;
 							}
-							wrapper.Append (" " + t.Name + " {");
+							wrapper.Append(" " + t.Name + " {");
-							wrapper.AppendLine ();
+							wrapper.AppendLine();
 							closingBrackets++;
 							generatedLines++;
 						} else {
-							Console.WriteLine (n);
+							Console.WriteLine(n);
 						}
 					}
 				}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/ICSharpCode.NRefactory.CSharp.csproj

@@ -265,6 +265,8 @@
     <Compile Include="Refactoring\ContextAction\UseVarKeyword.cs" />
     <Compile Include="Refactoring\DocumentScript.cs" />
     <Compile Include="Refactoring\IContextAction.cs" />
+    <Compile Include="Refactoring\PatternHelper.cs" />
+    <Compile Include="Refactoring\RefactoringAstHelper.cs" />
     <Compile Include="Refactoring\RefactoringContext.cs" />
     <Compile Include="Refactoring\Script.cs" />
     <Compile Include="Refactoring\TypeSystemAstBuilder.cs" />
@@ -322,6 +324,19 @@
     <Compile Include="Refactoring\ContextAction\RemoveRegion.cs" />
     <Compile Include="Refactoring\ContextAction\GenerateProperty.cs" />
     <Compile Include="Ast\Roles.cs" />
+    <Compile Include="Refactoring\Inspector\ConditionalToNullCoalescingInspector.cs" />
+    <Compile Include="Refactoring\IInspector.cs" />
+    <Compile Include="Refactoring\InspectionIssue.cs" />
+    <Compile Include="Refactoring\BaseRefactoringContext.cs" />
+    <Compile Include="Refactoring\Inspector\GatherVisitorBase.cs" />
+    <Compile Include="Refactoring\Inspector\NotImplementedExceptionInspector.cs" />
+    <Compile Include="Refactoring\Inspector\RedundantInternalInspector.cs" />
+    <Compile Include="Refactoring\Inspector\RedundantNamespaceUsageInspector.cs" />
+    <Compile Include="Refactoring\Inspector\RedundantPrivateInspector.cs" />
+    <Compile Include="Refactoring\Inspector\RedundantThisInspector.cs" />
+    <Compile Include="Refactoring\Inspector\RedundantUsingInspector.cs" />
+    <Compile Include="Refactoring\Inspector\StringIsNullOrEmptyInspector.cs" />
+    <Compile Include="Refactoring\Inspector\UseVarKeywordInspector.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\ICSharpCode.NRefactory\ICSharpCode.NRefactory.csproj">
@@ -332,6 +347,7 @@
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.Targets" />
   <ItemGroup>
     <Folder Include="Completion\" />
+    <Folder Include="Refactoring\Inspector\" />
   </ItemGroup>
   <ProjectExtensions>
     <MonoDevelop>

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/BaseRefactoringContext.cs

@@ -0,0 +1,103 @@
+// 
+// BaseRefactoringContext.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+using System;
+using System.Linq;
+using System.Threading;
+using ICSharpCode.NRefactory.CSharp.Resolver;
+using ICSharpCode.NRefactory.CSharp.TypeSystem;
+using ICSharpCode.NRefactory.Semantics;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.NRefactory.TypeSystem.Implementation;
+using ICSharpCode.NRefactory.Editor;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	public abstract class BaseRefactoringContext
+	{
+		protected readonly CSharpAstResolver resolver;
+		readonly CancellationToken cancellationToken;
+		
+		public virtual bool Supports(Version version)
+		{
+			return true;
+		}
+		
+		public CancellationToken CancellationToken {
+			get { return cancellationToken; }
+		}
+		
+		public virtual AstNode RootNode {
+			get { return resolver.RootNode; }
+		}
+
+		public ICompilation Compilation {
+			get { return resolver.Compilation; }
+		}
+
+		public BaseRefactoringContext (ICSharpCode.NRefactory.CSharp.Resolver.CSharpAstResolver resolver, System.Threading.CancellationToken cancellationToken)
+		{
+			this.resolver = resolver;
+			this.cancellationToken = cancellationToken;
+		}
+
+		#region Resolving
+		public ResolveResult Resolve (AstNode node)
+		{
+			return resolver.Resolve (node, cancellationToken);
+		}
+		
+		public CSharpResolver GetResolverStateBefore(AstNode node)
+		{
+			return resolver.GetResolverStateBefore (node, cancellationToken);
+		}
+		
+		public CSharpResolver GetResolverStateAfter(AstNode node)
+		{
+			return resolver.GetResolverStateAfter (node, cancellationToken);
+		}
+
+		public IType ResolveType (AstType type)
+		{
+			return resolver.Resolve (type, cancellationToken).Type;
+		}
+		
+		public IType GetExpectedType (Expression expression)
+		{
+			return resolver.GetExpectedType(expression, cancellationToken);
+		}
+		
+		public Conversion GetConversion (Expression expression)
+		{
+			return resolver.GetConversion(expression, cancellationToken);
+		}
+		#endregion
+		
+		public abstract Script StartScript();
+
+	}
+	
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/CheckIfParameterIsNull.cs

@@ -46,10 +46,10 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			if (bodyStatement == null)
 				return false;
 			
-			if (parameter.Type is PrimitiveType)
+			var type = context.ResolveType(parameter.Type);
-				return (((PrimitiveType)parameter.Type).Keyword == "object" || ((PrimitiveType)parameter.Type).Keyword == "string") && !HasNullCheck (parameter);
+			if (type.IsReferenceType == false)
+				return false;
 			
-			// TODO: check for structs
 			return !HasNullCheck (parameter);
 		}
 		
@@ -83,25 +83,20 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 		
 		class CheckNullVisitor : DepthFirstAstVisitor<object, object>
 		{
-			ParameterDeclaration parameter;
+			readonly Expression pattern;
 			
-			public bool ContainsNullCheck { 
+			internal bool ContainsNullCheck;
-				get;
-				set;
-			}
 			
 			public CheckNullVisitor (ParameterDeclaration parameter)
 			{
-				this.parameter = parameter;
+				this.pattern = PatternHelper.CommutativeOperator(new IdentifierExpression(parameter.Name), BinaryOperatorType.Any, new NullReferenceExpression());
 			}
 			
 			public override object VisitIfElseStatement (IfElseStatement ifElseStatement, object data)
 			{
 				if (ifElseStatement.Condition is BinaryOperatorExpression) {
 					var binOp = ifElseStatement.Condition as BinaryOperatorExpression;
-					if ((binOp.Operator == BinaryOperatorType.Equality || binOp.Operator == BinaryOperatorType.InEquality) &&
+					if ((binOp.Operator == BinaryOperatorType.Equality || binOp.Operator == BinaryOperatorType.InEquality) && pattern.IsMatch(binOp)) {
-						binOp.Left.IsMatch (new IdentifierExpression (parameter.Name)) && binOp.Right.IsMatch (new NullReferenceExpression ()) || 
-						binOp.Right.IsMatch (new IdentifierExpression (parameter.Name)) && binOp.Left.IsMatch (new NullReferenceExpression ())) {
 						ContainsNullCheck = true;
 					}
 				}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/ConvertForeachToFor.cs

@@ -54,6 +54,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			var result = context.Resolve (foreachStatement.InExpression);
 			var countProperty = GetCountProperty (result.Type);
 			
+			// TODO: use another variable name if 'i' is already in use
 			var initializer = new VariableDeclarationStatement (new PrimitiveType ("int"), "i", new PrimitiveExpression (0));
 			var id1 = new IdentifierExpression ("i");
 			var id2 = id1.Clone ();
@@ -88,7 +89,10 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			if (astNode == null)
 				return null;
 			var result = (astNode as ForeachStatement) ?? astNode.Parent as ForeachStatement;
-			if (result == null || context.Resolve (result.InExpression) == null)
+			if (result == null)
+				return null;
+			var collection = context.Resolve (result.InExpression);
+			if (collection.Type.Kind != TypeKind.Array && !collection.Type.GetProperties(p => p.IsIndexer).Any())
 				return null;
 			return result;
 		}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/IInspector.cs

@@ -0,0 +1,36 @@
+// 
+// IInspector.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using System.Collections.Generic;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	public interface IInspector
+	{
+		IEnumerable<InspectionIssue> Run (BaseRefactoringContext context);
+	}
+}
+

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/InspectionIssue.cs

@@ -0,0 +1,61 @@
+// 
+// InspectionIssue.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	public class InspectionIssue
+	{
+		public string Title {
+			get;
+			private set;
+		}
+		
+		public TextLocation Start {
+			get;
+			private set;
+		}
+		
+		public TextLocation End {
+			get;
+			private set;
+		}
+
+		public System.Action Fix {
+			get;
+			private set;
+		}
+
+		public InspectionIssue (string title, TextLocation start, TextLocation end, System.Action fix)
+		{
+			this.Title = title;
+			this.Start = start;
+			this.End = end;
+			this.Fix = fix;
+		}
+	}
+}
+

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/ConditionalToNullCoalescingInspector.cs

@@ -0,0 +1,98 @@
+// 
+// ConditionalToNullCoalescingInspector.cs
+//
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using ICSharpCode.NRefactory.PatternMatching;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Checks for "a != null ? a : other"<expr>
+	/// Converts to: "a ?? other"<expr>
+	/// </summary>
+	public class ConditionalToNullCoalescingInspector : IInspector
+	{
+		static readonly Pattern pattern = new Choice {
+			// a != null ? a : other
+			new ConditionalExpression(
+				PatternHelper.CommutativeOperator(new AnyNode("a"), BinaryOperatorType.InEquality, new NullReferenceExpression()),
+				new Backreference("a"),
+				new AnyNode("other")
+			),
+			// a == null ? other : a
+			new ConditionalExpression(
+				PatternHelper.CommutativeOperator(new AnyNode("a"), BinaryOperatorType.Equality, new NullReferenceExpression()),
+				new AnyNode("other"),
+				new Backreference("a")
+			),
+		};
+		
+		string title = "Convert to '??' expression";
+
+		public string Title {
+			get {
+				return title;
+			}
+			set {
+				title = value;
+			}
+		}
+
+		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context, this);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+		
+		class GatherVisitor : GatherVisitorBase
+		{
+			readonly ConditionalToNullCoalescingInspector inspector;
+			
+			public GatherVisitor (BaseRefactoringContext ctx, ConditionalToNullCoalescingInspector inspector) : base (ctx)
+			{
+				this.inspector = inspector;
+			}
+
+			public override void VisitConditionalExpression(ConditionalExpression conditionalExpression)
+			{
+				Match m = pattern.Match(conditionalExpression);
+				if (m.Success) {
+					var a = m.Get<Expression>("a").Single();
+					var other = m.Get<Expression>("other").Single();
+					AddIssue(conditionalExpression, inspector.Title, delegate {
+						using (var script = ctx.StartScript ()) {
+							var expr = new BinaryOperatorExpression (a.Clone (), BinaryOperatorType.NullCoalescing, other.Clone ());
+							script.Replace (conditionalExpression, expr);
+						}
+					});
+				}
+				base.VisitConditionalExpression (conditionalExpression);
+			}
+		}
+	}
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/GatherVisitorBase.cs

@@ -0,0 +1,63 @@
+// 
+// GatherVisitorBase.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using ICSharpCode.NRefactory.CSharp.Refactoring;
+using System.Collections.Generic;
+
+namespace ICSharpCode.NRefactory.CSharp
+{
+	class GatherVisitorBase : DepthFirstAstVisitor
+	{
+		protected readonly BaseRefactoringContext ctx;
+
+		public readonly List<InspectionIssue> FoundIssues = new List<InspectionIssue> ();
+
+		public GatherVisitorBase (BaseRefactoringContext ctx)
+		{
+			this.ctx = ctx;
+		}
+		
+		protected override void VisitChildren (AstNode node)
+		{
+			if (ctx.CancellationToken.IsCancellationRequested)
+				return;
+			base.VisitChildren (node);
+		}
+		
+		protected void AddIssue (AstNode node, string title, System.Action fix = null)
+		{
+			FoundIssues.Add (new InspectionIssue (title, node.StartLocation, node.EndLocation, fix));
+		}
+
+		protected void AddIssue(TextLocation start, TextLocation end, string title, System.Action fix = null)
+		{
+			FoundIssues.Add (new InspectionIssue (title, start, end, fix));
+		}
+	}
+		
+	
+}
+

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/NotImplementedExceptionInspector.cs

@@ -0,0 +1,77 @@
+// 
+// NotImplementedExceptionInspector.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using ICSharpCode.NRefactory.PatternMatching;
+using System.Collections.Generic;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// This inspector just shows that there is a not implemented exception. It doesn't offer a fix.
+	/// Should only be shown in overview bar, no underlining.
+	/// </summary>
+	public class NotImplementedExceptionInspector : IInspector
+	{
+		string title = "NotImplemented exception thrown";
+
+		public string Title {
+			get {
+				return title;
+			}
+			set {
+				title = value;
+			}
+		}
+
+		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context, this);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+
+		class GatherVisitor : GatherVisitorBase
+		{
+			readonly NotImplementedExceptionInspector inspector;
+			
+			public GatherVisitor (BaseRefactoringContext ctx, NotImplementedExceptionInspector inspector) : base (ctx)
+			{
+				this.inspector = inspector;
+			}
+
+			public override void VisitThrowStatement(ThrowStatement throwStatement)
+			{
+				var result = ctx.Resolve (throwStatement.Expression);
+				if (result.Type.Equals (ctx.Compilation.FindType (typeof(System.NotImplementedException))))
+					AddIssue (throwStatement, inspector.Title);
+
+				base.VisitThrowStatement(throwStatement);
+			}
+		}
+	}
+}
+

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/RedundantInternalInspector.cs

@@ -0,0 +1,82 @@
+// 
+// RedundantInternalInspector.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+using System;
+using ICSharpCode.NRefactory.PatternMatching;
+using System.Collections.Generic;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Finds redundant internal modifiers.
+	/// </summary>
+	public class RedundantInternalInspector : IInspector
+	{
+		string title = "Remove redundant 'internal' modifier";
+
+		public string Title {
+			get {
+				return title;
+			}
+			set {
+				title = value;
+			}
+		}
+
+		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context, this);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+
+		class GatherVisitor : GatherVisitorBase
+		{
+			readonly RedundantInternalInspector inspector;
+			
+			public GatherVisitor (BaseRefactoringContext ctx, RedundantInternalInspector inspector) : base (ctx)
+			{
+				this.inspector = inspector;
+			}
+
+			public override void VisitTypeDeclaration(TypeDeclaration typeDeclaration)
+			{
+				foreach (var token_ in typeDeclaration.ModifierTokens) {
+					var token = token_;
+					if (token.Modifier == Modifiers.Internal) {
+						AddIssue(token, inspector.Title, delegate {
+							using (var script = ctx.StartScript ()) {
+								script.Remove(token);
+							}
+						});
+					}
+				}
+			}
+		}
+	}
+}
+

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/RedundantNamespaceUsageInspector.cs

@@ -0,0 +1,95 @@
+// 
+// RedundantNamespaceUsageInspector.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+using ICSharpCode.NRefactory.Semantics;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Finds redundant namespace usages.
+	/// </summary>
+	public class RedundantNamespaceUsageInspector : IInspector
+	{
+		string title = "Remove redundant namespace usage";
+
+		public string Title {
+			get {
+				return title;
+			}
+			set {
+				title = value;
+			}
+		}
+
+		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context, this);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+
+		class GatherVisitor : GatherVisitorBase
+		{
+			readonly RedundantNamespaceUsageInspector inspector;
+			
+			public GatherVisitor (BaseRefactoringContext ctx, RedundantNamespaceUsageInspector inspector) : base (ctx)
+			{
+				this.inspector = inspector;
+			}
+
+			public override void VisitMemberReferenceExpression(MemberReferenceExpression memberReferenceExpression)
+			{
+				base.VisitMemberReferenceExpression(memberReferenceExpression);
+				
+				var result = ctx.Resolve(memberReferenceExpression.Target);
+				if (!(result is NamespaceResolveResult)) {
+					return;
+				}
+				var wholeResult = ctx.Resolve(memberReferenceExpression);
+				if (!(wholeResult is TypeResolveResult)) {
+					return;
+				}
+
+				var state = ctx.GetResolverStateBefore(memberReferenceExpression);
+				var lookupName = state.LookupSimpleNameOrTypeName(memberReferenceExpression.MemberName, new List<IType> (), SimpleNameLookupMode.Expression);
+				
+				if (lookupName is TypeResolveResult && !lookupName.IsError && wholeResult.Type.Equals(lookupName.Type)) {
+					AddIssue(memberReferenceExpression.StartLocation, memberReferenceExpression.MemberNameToken.StartLocation, inspector.Title, delegate {
+						using (var script = ctx.StartScript ()) {
+							script.Replace(memberReferenceExpression, RefactoringAstHelper.RemoveTarget(memberReferenceExpression));
+						}
+					}
+					);
+				}
+			}
+		}
+	}
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/RedundantPrivateInspector.cs

@@ -0,0 +1,143 @@
+// 
+// RedundantPrivateInspector.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+using System;
+using ICSharpCode.NRefactory.PatternMatching;
+using System.Collections.Generic;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Finds redundant internal modifiers.
+	/// </summary>
+	public class RedundantPrivateInspector : IInspector
+	{
+		string title = "Remove redundant 'private' modifier";
+
+		public string Title {
+			get {
+				return title;
+			}
+			set {
+				title = value;
+			}
+		}
+
+		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context, this);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+
+		class GatherVisitor : GatherVisitorBase
+		{
+			readonly RedundantPrivateInspector inspector;
+			
+			public GatherVisitor (BaseRefactoringContext ctx, RedundantPrivateInspector inspector) : base (ctx)
+			{
+				this.inspector = inspector;
+			}
+
+			void CheckNode(EntityDeclaration node)
+			{
+				foreach (var token_ in node.ModifierTokens) {
+					var token = token_;
+					if (token.Modifier == Modifiers.Private) {
+						AddIssue(token, inspector.Title, delegate {
+							using (var script = ctx.StartScript ()) {
+								script.Remove(token);
+							}
+						});
+					}
+				}
+			}
+
+			public override void VisitMethodDeclaration(MethodDeclaration methodDeclaration)
+			{
+				base.VisitMethodDeclaration(methodDeclaration);
+				CheckNode(methodDeclaration);
+			}
+			
+			public override void VisitFieldDeclaration(FieldDeclaration fieldDeclaration)
+			{
+				base.VisitFieldDeclaration(fieldDeclaration);
+				CheckNode(fieldDeclaration);
+			}
+			
+			public override void VisitPropertyDeclaration(PropertyDeclaration propertyDeclaration)
+			{
+				base.VisitPropertyDeclaration(propertyDeclaration);
+				CheckNode(propertyDeclaration);
+			}
+
+			public override void VisitIndexerDeclaration(IndexerDeclaration indexerDeclaration)
+			{
+				base.VisitIndexerDeclaration(indexerDeclaration);
+				CheckNode(indexerDeclaration);
+			}
+
+			public override void VisitEventDeclaration(EventDeclaration eventDeclaration)
+			{
+				base.VisitEventDeclaration(eventDeclaration);
+				CheckNode(eventDeclaration);
+			}
+			
+			public override void VisitCustomEventDeclaration(CustomEventDeclaration eventDeclaration)
+			{
+				base.VisitCustomEventDeclaration(eventDeclaration);
+				CheckNode(eventDeclaration);
+			}
+			
+			public override void VisitConstructorDeclaration(ConstructorDeclaration constructorDeclaration)
+			{
+				base.VisitConstructorDeclaration(constructorDeclaration);
+				CheckNode(constructorDeclaration);
+			}
+
+			public override void VisitOperatorDeclaration(OperatorDeclaration operatorDeclaration)
+			{
+				base.VisitOperatorDeclaration(operatorDeclaration);
+				CheckNode(operatorDeclaration);
+			}
+
+			public override void VisitFixedFieldDeclaration(FixedFieldDeclaration fixedFieldDeclaration)
+			{
+				base.VisitFixedFieldDeclaration(fixedFieldDeclaration);
+				CheckNode(fixedFieldDeclaration);
+			}
+
+			public override void VisitTypeDeclaration(TypeDeclaration typeDeclaration)
+			{
+				if (!(typeDeclaration.Parent is TypeDeclaration)) {
+					CheckNode(typeDeclaration);
+				}
+				base.VisitTypeDeclaration(typeDeclaration);
+			}
+		}
+	}
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/RedundantThisInspector.cs

@@ -0,0 +1,119 @@
+// 
+// RedundantThisInspector.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+using System;
+using ICSharpCode.NRefactory.PatternMatching;
+using System.Collections.Generic;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.NRefactory.Semantics;
+using ICSharpCode.NRefactory.CSharp.Resolver;
+using System.Linq;
+
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Finds redundant namespace usages.
+	/// </summary>
+	public class RedundantThisInspector : IInspector
+	{
+		string title = "Remove redundant 'this.'";
+
+		public string Title {
+			get {
+				return title;
+			}
+			set {
+				title = value;
+			}
+		}
+
+		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context, this);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+
+		class GatherVisitor : GatherVisitorBase
+		{
+			readonly RedundantThisInspector inspector;
+			
+			public GatherVisitor (BaseRefactoringContext ctx, RedundantThisInspector inspector) : base (ctx)
+			{
+				this.inspector = inspector;
+			}
+
+			static IMember GetMember (ResolveResult result)
+			{
+				if (result is MemberResolveResult) {
+					return ((MemberResolveResult)result).Member;
+				} else if (result is MethodGroupResolveResult) {
+					return ((MethodGroupResolveResult)result).Methods.FirstOrDefault ();
+				}
+
+				return null;
+			}
+
+			public override void VisitThisReferenceExpression (ThisReferenceExpression thisReferenceExpression)
+			{
+				base.VisitThisReferenceExpression (thisReferenceExpression);
+				var memberReference = thisReferenceExpression.Parent as MemberReferenceExpression;
+				if (memberReference == null) {
+					return;
+				}
+
+				var state = ctx.GetResolverStateAfter (thisReferenceExpression);
+				var wholeResult = ctx.Resolve (memberReference);
+			
+				IMember member = GetMember (wholeResult);
+				if (member == null) { 
+					return;
+				}
+
+				var result = state.LookupSimpleNameOrTypeName (memberReference.MemberName, EmptyList<IType>.Instance, SimpleNameLookupMode.Expression);
+			
+				bool isRedundant;
+				if (result is MemberResolveResult) {
+					isRedundant = ((MemberResolveResult)result).Member.Region.Equals(member.Region);
+				} else if (result is MethodGroupResolveResult) {
+					isRedundant = ((MethodGroupResolveResult)result).Methods.Any(m => m.Region.Equals(member.Region));
+				} else {
+					return;
+				}
+
+				if (isRedundant) {
+					AddIssue(thisReferenceExpression.StartLocation, memberReference.MemberNameToken.StartLocation, inspector.Title, delegate {
+						using (var script = ctx.StartScript ()) {
+							script.Replace(memberReference, RefactoringAstHelper.RemoveTarget(memberReference));
+						}
+					}
+					);
+				}
+			}
+		}
+	}
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/RedundantUsingInspector.cs

@@ -0,0 +1,77 @@
+// 
+// RedundantUsingInspector.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+using System;
+using ICSharpCode.NRefactory.PatternMatching;
+using System.Collections.Generic;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.NRefactory.Semantics;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Finds redundant using declarations.
+	/// </summary>
+	public class RedundantUsingInspector : IInspector
+	{
+		string title = "Remove redundant using";
+
+		public string Title {
+			get {
+				return title;
+			}
+			set {
+				title = value;
+			}
+		}
+
+		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context, this);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+
+		class GatherVisitor : GatherVisitorBase
+		{
+			readonly RedundantUsingInspector inspector;
+			
+			public GatherVisitor (BaseRefactoringContext ctx, RedundantUsingInspector inspector) : base (ctx)
+			{
+				this.inspector = inspector;
+			}
+
+			public override void VisitUsingDeclaration(UsingDeclaration usingDeclaration)
+			{
+				base.VisitUsingDeclaration(usingDeclaration);
+				// TODO
+				//			return cSharpResolver.usedScopes
+				//				.OfType<ITypeOrNamespaceReference> ()
+				//				.Any (u => u.ResolveNamespace (ctx).NamespaceName == ns) || additionalNamespaces.Contains (ns);
+			}
+		}
+	}
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/StringIsNullOrEmptyInspector.cs

@@ -0,0 +1,121 @@
+// 
+// StringIsNullOrEmptyInspector.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using ICSharpCode.NRefactory.PatternMatching;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Checks for str == null && str == "" 
+	/// Converts to: string.IsNullOrEmpty (str)
+	/// </summary>
+	public class StringIsNullOrEmptyInspector : IInspector
+	{
+		static readonly Pattern pattern = new Choice {
+			// str == null || str == "" 
+			new BinaryOperatorExpression (
+				PatternHelper.CommutativeOperator(new AnyNode ("str"), BinaryOperatorType.Equality, new NullReferenceExpression ()),
+				BinaryOperatorType.ConditionalOr,
+				PatternHelper.CommutativeOperator(new Backreference ("str"), BinaryOperatorType.Equality, new PrimitiveExpression (""))
+			),
+			// str == "" || str == null
+			new BinaryOperatorExpression (
+				PatternHelper.CommutativeOperator(new Backreference ("str"), BinaryOperatorType.Equality, new PrimitiveExpression ("")),
+				BinaryOperatorType.ConditionalOr,
+				PatternHelper.CommutativeOperator(new AnyNode ("str"), BinaryOperatorType.Equality, new NullReferenceExpression ())
+			),
+		};
+
+		static readonly Pattern negPattern = new Choice {
+			// str != null && str != "" 
+			new BinaryOperatorExpression (
+				PatternHelper.CommutativeOperator(new AnyNode ("str"), BinaryOperatorType.InEquality, new NullReferenceExpression ()),
+				BinaryOperatorType.ConditionalAnd,
+				PatternHelper.CommutativeOperator(new Backreference ("str"), BinaryOperatorType.InEquality, new PrimitiveExpression (""))
+			),
+			// str != "" && str != null
+			new BinaryOperatorExpression (
+				PatternHelper.CommutativeOperator(new Backreference ("str"), BinaryOperatorType.InEquality, new PrimitiveExpression ("")),
+				BinaryOperatorType.ConditionalAnd,
+				PatternHelper.CommutativeOperator(new AnyNode ("str"), BinaryOperatorType.InEquality, new NullReferenceExpression ())
+			),
+		};
+		
+		string title = "Use string.IsNullOrEmpty";
+
+		public string Title {
+			get {
+				return title;
+			}
+			set {
+				title = value;
+			}
+		}
+
+		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context, this);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+		
+		class GatherVisitor : GatherVisitorBase
+		{
+			readonly StringIsNullOrEmptyInspector inspector;
+			
+			public GatherVisitor (BaseRefactoringContext ctx, StringIsNullOrEmptyInspector inspector) : base (ctx)
+			{
+				this.inspector = inspector;
+			}
+
+			public override void VisitBinaryOperatorExpression(BinaryOperatorExpression binaryOperatorExpression)
+			{
+				base.VisitBinaryOperatorExpression(binaryOperatorExpression);
+				Match m = pattern.Match(binaryOperatorExpression);
+				bool isNegated = false;
+				if (!m.Success) {
+					m = negPattern.Match(binaryOperatorExpression);
+					isNegated = true;
+				}
+				if (m.Success) {
+					var str = m.Get<Expression>("str").Single();
+					AddIssue(binaryOperatorExpression, inspector.Title, delegate {
+						using (var script = ctx.StartScript ()) {
+							Expression expr = new PrimitiveType ("string").Invoke("IsNullOrEmpty", str.Clone());
+							if (isNegated)
+								expr = new UnaryOperatorExpression (UnaryOperatorType.Not, expr);
+							script.Replace(binaryOperatorExpression, expr);
+						}
+					});
+					return;
+				}
+			}
+
+		}
+	}
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/Inspector/UseVarKeywordInspector.cs

@@ -0,0 +1,113 @@
+// 
+// UseVarKeywordInspector.cs
+//  
+// Author:
+//       Mike Krüger <mkrueger@xamarin.com>
+// 
+// Copyright (c) 2012 Xamarin <http://xamarin.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using ICSharpCode.NRefactory.PatternMatching;
+using System.Collections.Generic;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.NRefactory.Semantics;
+using System.Linq;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Checks for places where the 'var' keyword can be used. Note that the action is actually done with a context
+	/// action.
+	/// </summary>
+	public class UseVarKeywordInspector : IInspector
+	{
+		string title = "Use 'var' keyword";
+
+		public string Title {
+			get {
+				return title;
+			}
+			set {
+				title = value;
+			}
+		}
+
+		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context, this);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+
+		class GatherVisitor : GatherVisitorBase
+		{
+			readonly UseVarKeywordInspector inspector;
+			
+			public GatherVisitor (BaseRefactoringContext ctx, UseVarKeywordInspector inspector) : base (ctx)
+			{
+				this.inspector = inspector;
+			}
+
+			public override void VisitVariableDeclarationStatement(VariableDeclarationStatement variableDeclarationStatement)
+			{
+				base.VisitVariableDeclarationStatement(variableDeclarationStatement);
+				if (variableDeclarationStatement.Type is PrimitiveType) {
+					return;
+				}
+				if (variableDeclarationStatement.Type is SimpleType && ((SimpleType)variableDeclarationStatement.Type).Identifier == "var") { 
+					return;
+				}
+				if (variableDeclarationStatement.Variables.Count != 1) {
+					return;
+				}
+				
+				//only checks for cases where the type would be obvious - assignment of new, cast, etc.
+				//also check the type actually matches else the user might want to assign different subclasses later
+				var v = variableDeclarationStatement.Variables.Single();
+				
+				var arrCreate = v.Initializer as ArrayCreateExpression;
+				if (arrCreate != null) {
+					var n = variableDeclarationStatement.Type as ComposedType;
+					//FIXME: check the specifier compatibility
+					if (n != null && n.ArraySpecifiers.Any() && n.BaseType.IsMatch(arrCreate.Type)) {
+						AddIssue(variableDeclarationStatement);
+					}
+				}
+				var objCreate = v.Initializer as ObjectCreateExpression;
+				if (objCreate != null && objCreate.Type.IsMatch(variableDeclarationStatement.Type)) {
+					AddIssue(variableDeclarationStatement);
+				}
+				var asCast = v.Initializer as AsExpression;
+				if (asCast != null && asCast.Type.IsMatch(variableDeclarationStatement.Type)) {
+					AddIssue(variableDeclarationStatement);
+				}
+				var cast = v.Initializer as CastExpression;
+				if (cast != null && cast.Type.IsMatch(variableDeclarationStatement.Type)) {
+					AddIssue(variableDeclarationStatement);
+				}
+			}
+			
+			void AddIssue(VariableDeclarationStatement variableDeclarationStatement)
+			{
+				AddIssue(variableDeclarationStatement.Type, inspector.Title);
+			}
+		}
+	}
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/PatternHelper.cs

@@ -0,0 +1,40 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using ICSharpCode.NRefactory.PatternMatching;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Helper class for constructing pattern ASTs.
+	/// </summary>
+	public class PatternHelper
+	{
+		/// <summary>
+		/// Produces a choice pattern for <c>expr1 op expr2</c> or <c>expr2 op expr1</c>.
+		/// </summary>
+		public static Expression CommutativeOperator(Expression expr1, BinaryOperatorType op, Expression expr2)
+		{
+			return new Choice {
+				new BinaryOperatorExpression(expr1, op, expr2),
+				new BinaryOperatorExpression(expr2.Clone(), op, expr1.Clone())
+			};
+		}
+	}
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/RefactoringAstHelper.cs

@@ -0,0 +1,49 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	/// <summary>
+	/// Helper methods for constructing ASTs for refactoring.
+	/// These helpers work with frozen ASTs, i.e. they clone input nodes.
+	/// </summary>
+	public class RefactoringAstHelper
+	{
+		/// <summary>
+		/// Removes the target from a member reference while preserving the identifier and type arguments.
+		/// </summary>
+		public static IdentifierExpression RemoveTarget(MemberReferenceExpression mre)
+		{
+			IdentifierExpression ident = new IdentifierExpression(mre.MemberName);
+			ident.TypeArguments.AddRange(mre.TypeArguments.Select(t => t.Clone()));
+			return ident;
+		}
+		
+		/// <summary>
+		/// Removes the target from a member reference while preserving the identifier and type arguments.
+		/// </summary>
+		public static SimpleType RemoveTarget(MemberType memberType)
+		{
+			return new SimpleType(memberType.MemberName, memberType.TypeArguments.Select(t => t.Clone()));
+		}
+	}
+}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Refactoring/RefactoringContext.cs

@@ -36,36 +36,14 @@ using ICSharpCode.NRefactory.Editor;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
-	public abstract class RefactoringContext
+	public abstract class RefactoringContext : BaseRefactoringContext
 	{
-		readonly protected CSharpAstResolver resolver;
+		public RefactoringContext(CSharpAstResolver resolver, CancellationToken cancellationToken) : base  (resolver, cancellationToken)
-		readonly CancellationToken cancellationToken;
-		
-		public RefactoringContext(CSharpAstResolver resolver, CancellationToken cancellationToken)
 		{
-			this.resolver = resolver;
-			this.cancellationToken = cancellationToken;
-		}
-		
-		public CancellationToken CancellationToken {
-			get { return cancellationToken; }
-		}
-		
-		public virtual AstNode RootNode {
-			get { return resolver.RootNode; }
 		}
 
 		public abstract TextLocation Location { get; }
 
-		public virtual bool Supports(Version version)
-		{
-			return true;
-		}
-		
-		public ICompilation Compilation {
-			get { return resolver.Compilation; }
-		}
-		
 		public virtual AstType CreateShortType (IType fullType)
 		{
 			var csResolver = resolver.GetResolverStateBefore(GetNode());
@@ -133,28 +111,6 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 		public abstract string GetText (ISegment segment);
 		#endregion
 
-		#region Resolving
-		public ResolveResult Resolve (AstNode node)
-		{
-			return resolver.Resolve (node, cancellationToken);
-		}
-		
-		public IType ResolveType (AstType type)
-		{
-			return resolver.Resolve (type, cancellationToken).Type;
-		}
-		
-		public IType GetExpectedType (Expression expression)
-		{
-			return resolver.GetExpectedType(expression, cancellationToken);
-		}
-		
-		public Conversion GetConversion (Expression expression)
-		{
-			return resolver.GetConversion(expression, cancellationToken);
-		}
-		#endregion
-		
 		public virtual string GetNameProposal (string name, bool camelCase = true)
 		{
 			string baseName = (camelCase ? char.ToLower (name [0]) : char.ToUpper (name [0])) + name.Substring (1);
@@ -175,8 +131,6 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 		{
 			return baseName + (number > 0 ? (number + 1).ToString () : "");
 		}
-		
-		public abstract Script StartScript();
 	}
 }
 

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Resolver/CSharpConversions.cs

@@ -805,10 +805,14 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				}
 			}
 			var or = rr.PerformOverloadResolution(compilation, args, allowExpandingParams: false, conversions: this);
-			if (or.FoundApplicableCandidate)
+			if (or.FoundApplicableCandidate) {
-				return Conversion.MethodGroupConversion((IMethod)or.GetBestCandidateWithSubstitutedTypeArguments());
+				IMethod method = (IMethod)or.GetBestCandidateWithSubstitutedTypeArguments();
-			else
+				var thisRR = rr.TargetResult as ThisResolveResult;
+				bool isVirtual = method.IsOverridable && !(thisRR != null && thisRR.CausesNonVirtualInvocation);
+				return Conversion.MethodGroupConversion(method, isVirtual);
+			} else {
 				return Conversion.None;
+			}
 		}
 		#endregion
 		

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Resolver/CSharpResolver.cs

@@ -1167,13 +1167,16 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal readonly IParameterizedMember nonLiftedOperator;
 			
 			public LiftedUserDefinedOperator(IMethod nonLiftedMethod)
-				: base(nonLiftedMethod.DeclaringType, (IMethod)nonLiftedMethod.MemberDefinition,
+				: base(nonLiftedMethod, TypeParameterSubstitution.Identity)
-				       EmptyList<IType>.Instance, new MakeNullableVisitor(nonLiftedMethod.Compilation))
 			{
 				this.nonLiftedOperator = nonLiftedMethod;
+				var substitution = new MakeNullableVisitor(nonLiftedMethod.Compilation);
+				this.Parameters = base.CreateParameters(substitution);
 				// Comparison operators keep the 'bool' return type even when lifted.
 				if (IsComparisonOperator(nonLiftedMethod))
 					this.ReturnType = nonLiftedMethod.ReturnType;
+				else
+					this.ReturnType = nonLiftedMethod.ReturnType.AcceptVisitor(substitution);
 			}
 			
 			public IList<IParameter> NonLiftedParameters {
@@ -1726,13 +1729,13 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 					if (typeArguments != null && typeArguments.Count > 0) {
 						if (method.TypeParameters.Count != typeArguments.Count)
 							continue;
-						SpecializedMethod sm = new SpecializedMethod(method.DeclaringType, method, typeArguments);
+						SpecializedMethod sm = new SpecializedMethod(method, new TypeParameterSubstitution(null, typeArguments));
 						if (IsEligibleExtensionMethod(targetType, method, false, out inferredTypes))
 							outputGroup.Add(sm);
 					} else {
 						if (IsEligibleExtensionMethod(targetType, method, true, out inferredTypes)) {
 							if (substituteInferredTypes && inferredTypes != null) {
-								outputGroup.Add(new SpecializedMethod(method.DeclaringType, method, inferredTypes));
+								outputGroup.Add(new SpecializedMethod(method, new TypeParameterSubstitution(null, inferredTypes)));
 							} else {
 								outputGroup.Add(method);
 							}
@@ -1854,7 +1857,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			if (mgrr != null) {
 				OverloadResolution or = mgrr.PerformOverloadResolution(compilation, arguments, argumentNames, conversions: conversions);
 				if (or.BestCandidate != null) {
-					if (or.BestCandidate.IsStatic && !(mgrr.TargetResult is TypeResolveResult))
+					if (or.BestCandidate.IsStatic && !or.IsExtensionMethodInvocation && !(mgrr.TargetResult is TypeResolveResult))
 						return or.CreateResolveResult(new TypeResolveResult(mgrr.TargetResult.Type));
 					else
 						return or.CreateResolveResult(mgrr.TargetResult);

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Resolver/FindReferencedEntities.cs

@@ -27,13 +27,39 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 	/// </summary>
 	public sealed class FindReferencedEntities : IResolveVisitorNavigator
 	{
-		readonly Action<AstNode, IEntity> referenceFound;
+		readonly Action<AstNode, IMember> memberReferenceFound;
+		readonly Action<AstNode, IType> typeReferenceFound;
 		
+		/// <summary>
+		/// Creates a new FindReferencedEntities instance that
+		/// looks for entity definitions.
+		/// The visitor will report type definitions and member definitions (not specialized members).
+		/// </summary>
 		public FindReferencedEntities(Action<AstNode, IEntity> referenceFound)
 		{
 			if (referenceFound == null)
 				throw new ArgumentNullException("referenceFound");
-			this.referenceFound = referenceFound;
+			this.memberReferenceFound = (node, member) => referenceFound(node, member.MemberDefinition);
+			this.typeReferenceFound = (node, type) => {
+				var def = type.GetDefinition();
+				if (def != null)
+					referenceFound(node, def);
+			};
+		}
+		
+		/// <summary>
+		/// Creates a new FindReferencedEntities instance that
+		/// looks for types and members.
+		/// The visitor will report parameterized types and potentially specialized members.
+		/// </summary>
+		public FindReferencedEntities(Action<AstNode, IType> typeReferenceFound, Action<AstNode, IMember> memberReferenceFound)
+		{
+			if (typeReferenceFound == null)
+				throw new ArgumentNullException("typeReferenceFound");
+			if (memberReferenceFound == null)
+				throw new ArgumentNullException("memberReferenceFound");
+			this.typeReferenceFound = typeReferenceFound;
+			this.memberReferenceFound = memberReferenceFound;
 		}
 		
 		public ResolveVisitorNavigationMode Scan(AstNode node)
@@ -48,28 +74,26 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			
 			MemberResolveResult mrr = result as MemberResolveResult;
 			if (mrr != null) {
-				referenceFound(node, mrr.Member.MemberDefinition);
+				memberReferenceFound(node, mrr.Member);
 			}
 			TypeResolveResult trr = result as TypeResolveResult;
 			if (trr != null) {
-				ITypeDefinition typeDef = trr.Type.GetDefinition();
+				typeReferenceFound(node, trr.Type);
-				if (typeDef != null)
-					referenceFound(node, typeDef);
 			}
 			ForEachResolveResult ferr = result as ForEachResolveResult;
 			if (ferr != null) {
 				Resolved(node, ferr.GetEnumeratorCall);
 				if (ferr.CurrentProperty != null)
-					referenceFound(node, ferr.CurrentProperty.MemberDefinition);
+					memberReferenceFound(node, ferr.CurrentProperty);
 				if (ferr.MoveNextMethod != null)
-					referenceFound(node, ferr.MoveNextMethod.MemberDefinition);
+					memberReferenceFound(node, ferr.MoveNextMethod);
 			}
 		}
 		
 		public void ProcessConversion(Expression expression, ResolveResult result, Conversion conversion, IType targetType)
 		{
 			if (conversion.IsUserDefined || conversion.IsMethodGroupConversion) {
-				referenceFound(expression, conversion.Method.MemberDefinition);
+				memberReferenceFound(expression, conversion.Method);
 			}
 		}
 	}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Resolver/FindReferences.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 using ICSharpCode.NRefactory.CSharp.Refactoring;
@@ -42,9 +43,42 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 	{
 		#region Properties
 		/// <summary>
-		/// Gets/Sets whether to find type references even if an alias is being used.
+		/// Specifies whether to find type references even if an alias is being used.
+		/// Aliases may be <c>var</c> or <c>using Alias = ...;</c>.
 		/// </summary>
 		public bool FindTypeReferencesEvenIfAliased { get; set; }
+		
+		/// <summary>
+		/// Specifies whether find references should only look for specialized matches
+		/// with equal type parameter substitution to the member we are searching for.
+		/// </summary>
+		public bool FindOnlySpecializedReferences { get; set; }
+		
+		/// <summary>
+		/// If this option is enabled, find references on a overridden member
+		/// will find calls to the base member.
+		/// </summary>
+		public bool FindCallsThroughVirtualBaseMethod { get; set; }
+		
+		/// <summary>
+		/// If this option is enabled, find references on a member implementing
+		/// an interface will also find calls to the interface.
+		/// </summary>
+		public bool FindCallsThroughInterface { get; set; }
+		
+		/// <summary>
+		/// If this option is enabled, find references will look for all references
+		/// to the virtual method slot.
+		/// </summary>
+		public bool WholeVirtualSlot { get; set; }
+		
+		/// <summary>
+		/// Specifies whether to look for references in documentation comments.
+		/// This will find entity references in <c>cref</c> attributes and
+		/// parameter references in <c>&lt;param&gt;</c> and <c>&lt;paramref&gt;</c> tags.
+		/// TODO: implement this feature.
+		/// </summary>
+		public bool SearchInDocumentationComments { get; set; }
 		#endregion
 		
 		#region GetEffectiveAccessibility
@@ -110,6 +144,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			}
 			
 			internal string searchTerm;
+			internal FindReferences findReferences;
 			internal ICompilation declarationCompilation;
 			internal Accessibility accessibility;
 			internal ITypeDefinition topLevelTypeDefinition;
@@ -119,6 +154,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				FindReferenceNavigator n = factory(compilation);
 				if (n != null) {
 					n.callback = callback;
+					n.findReferences = findReferences;
 					return n;
 				} else {
 					return new ConstantModeResolveVisitorNavigator(ResolveVisitorNavigationMode.Skip, null);
@@ -145,6 +181,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		abstract class FindReferenceNavigator : IResolveVisitorNavigator
 		{
 			internal FoundReferenceCallback callback;
+			internal FindReferences findReferences;
 			
 			internal abstract bool CanMatch(AstNode node);
 			internal abstract bool IsMatch(ResolveResult rr);
@@ -185,6 +222,8 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		{
 			if (entity == null)
 				throw new ArgumentNullException("entity");
+			if (entity is IMember)
+				entity = NormalizeMember((IMember)entity);
 			Accessibility effectiveAccessibility = GetEffectiveAccessibility(entity);
 			ITypeDefinition topLevelTypeDefinition = entity.DeclaringTypeDefinition;
 			while (topLevelTypeDefinition != null && topLevelTypeDefinition.DeclaringTypeDefinition != null)
@@ -219,7 +258,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 					scope = GetSearchScopeForOperator((IMethod)entity);
 					break;
 				case EntityType.Constructor:
-					IMethod ctor = (IMethod)((IMethod)entity).MemberDefinition;
+					IMethod ctor = (IMethod)entity;
 					scope = FindObjectCreateReferences(ctor);
 					additionalScope = FindChainedConstructorReferences(ctor);
 					break;
@@ -233,11 +272,13 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				scope.accessibility = effectiveAccessibility;
 			scope.declarationCompilation = entity.Compilation;
 			scope.topLevelTypeDefinition = topLevelTypeDefinition;
+			scope.findReferences = this;
 			if (additionalScope != null) {
 				if (additionalScope.accessibility == Accessibility.None)
 					additionalScope.accessibility = effectiveAccessibility;
 				additionalScope.declarationCompilation = entity.Compilation;
 				additionalScope.topLevelTypeDefinition = topLevelTypeDefinition;
+				additionalScope.findReferences = this;
 				return new[] { scope, additionalScope };
 			} else {
 				return new[] { scope };
@@ -385,17 +426,14 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				if (searchTerm.Length > 9 && searchTerm.EndsWith("Attribute", StringComparison.Ordinal)) {
 					// The type might be an attribute, so we also need to look for the short form:
 					string shortForm = searchTerm.Substring(0, searchTerm.Length - 9);
-					additionalScope = new SearchScope(
+					additionalScope = FindTypeDefinitionReferences(typeDefinition, shortForm);
-						shortForm,
-						delegate (ICompilation compilation) {
-							ITypeDefinition imported = compilation.Import(typeDefinition);
-							if (imported != null)
-								return new FindTypeDefinitionReferencesNavigator(imported, shortForm);
-							else
-								return null;
-						});
 				}
 			}
+			return FindTypeDefinitionReferences(typeDefinition, searchTerm);
+		}
+		
+		SearchScope FindTypeDefinitionReferences(ITypeDefinition typeDefinition, string searchTerm)
+		{
 			return new SearchScope(
 				searchTerm,
 				delegate (ICompilation compilation) {
@@ -462,11 +500,10 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		SearchScope FindMemberReferences(IEntity member, Func<IMember, FindMemberReferencesNavigator> factory)
 		{
 			string searchTerm = member.Name;
-			IMember memberDefinition = ((IMember)member).MemberDefinition;
 			return new SearchScope(
 				searchTerm,
 				delegate(ICompilation compilation) {
-					IMember imported = compilation.Import(memberDefinition);
+					IMember imported = compilation.Import((IMember)member);
 					return imported != null ? factory(imported) : null;
 				});
 		}
@@ -478,7 +515,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			
 			public FindMemberReferencesNavigator(IMember member)
 			{
-				this.member = member.MemberDefinition;
+				this.member = member;
 				this.searchTerm = member.Name;
 			}
 			
@@ -506,8 +543,58 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				MemberResolveResult mrr = rr as MemberResolveResult;
-				return mrr != null && member == mrr.Member.MemberDefinition;
+				return mrr != null && findReferences.IsMemberMatch(member, mrr.Member, mrr.IsVirtualCall);
+			}
+		}
+		
+		IMember NormalizeMember(IMember member)
+		{
+			if (WholeVirtualSlot && member.IsOverride)
+				member = InheritanceHelper.GetBaseMembers(member, false).FirstOrDefault(m => !m.IsOverride) ?? member;
+			if (!FindOnlySpecializedReferences)
+				member = member.MemberDefinition;
+			return member;
+		}
+		
+		bool IsMemberMatch(IMember member, IMember referencedMember, bool isVirtualCall)
+		{
+			referencedMember = NormalizeMember(referencedMember);
+			if (member.Equals(referencedMember))
+				return true;
+			if (!isVirtualCall)
+				return false;
+			bool isInterfaceCall = referencedMember.DeclaringTypeDefinition != null && referencedMember.DeclaringTypeDefinition.Kind == TypeKind.Interface;
+			if (FindCallsThroughVirtualBaseMethod && member.IsOverride && !WholeVirtualSlot && !isInterfaceCall) {
+				// Test if 'member' overrides 'referencedMember':
+				foreach (var baseMember in InheritanceHelper.GetBaseMembers(member, false)) {
+					if (FindOnlySpecializedReferences) {
+						if (baseMember.Equals(referencedMember))
+							return true;
+					} else {
+						if (baseMember.MemberDefinition.Equals(referencedMember))
+							return true;
+					}
+					if (!baseMember.IsOverride)
+						break;
+				}
+				return false;
+			} else if (FindCallsThroughInterface && isInterfaceCall) {
+				// Test if 'member' implements 'referencedMember':
+				if (FindOnlySpecializedReferences) {
+					return member.ImplementedInterfaceMembers.Contains(referencedMember);
+				} else {
+					return member.ImplementedInterfaceMembers.Any(m => m.MemberDefinition.Equals(referencedMember));
+				}
 			}
+			return false;
+		}
+		
+		bool PerformVirtualLookup(IMember member, IMember referencedMember)
+		{
+			if (FindCallsThroughVirtualBaseMethod && member.IsOverride && !WholeVirtualSlot)
+				return true;
+			var typeDef = referencedMember.DeclaringTypeDefinition;
+			return FindCallsThroughInterface && typeDef != null && typeDef.Kind == TypeKind.Interface;
 		}
 		
 		sealed class FindFieldReferences : FindMemberReferencesNavigator
@@ -568,10 +655,9 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		#region Find References to IEnumerator.Current
 		SearchScope FindEnumeratorCurrentReferences(IProperty property)
 		{
-			IProperty propertyDefinition = (IProperty)property.MemberDefinition;
 			return new SearchScope(
 				delegate(ICompilation compilation) {
-					IProperty imported = compilation.Import(propertyDefinition);
+					IProperty imported = compilation.Import(property);
 					return imported != null ? new FindEnumeratorCurrentReferencesNavigator(imported) : null;
 				});
 		}
@@ -593,7 +679,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				ForEachResolveResult ferr = rr as ForEachResolveResult;
-				return ferr != null && ferr.CurrentProperty != null && ferr.CurrentProperty.MemberDefinition == property;
+				return ferr != null && ferr.CurrentProperty != null && findReferences.IsMemberMatch(property, ferr.CurrentProperty, true);
 			}
 		}
 		#endregion
@@ -601,8 +687,6 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		#region Find Method References
 		SearchScope GetSearchScopeForMethod(IMethod method)
 		{
-			method = (IMethod)method.MemberDefinition;
-			
 			Type specialNodeType;
 			switch (method.Name) {
 				case "Add":
@@ -708,18 +792,18 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 					var ferr = rr as ForEachResolveResult;
 					if (ferr != null) {
 						return IsMatch(ferr.GetEnumeratorCall)
-							|| (ferr.MoveNextMethod != null && method == ferr.MoveNextMethod.MemberDefinition);
+							|| (ferr.MoveNextMethod != null && findReferences.IsMemberMatch(method, ferr.MoveNextMethod, true));
 					}
 				}
 				var mrr = rr as MemberResolveResult;
-				return mrr != null && method == mrr.Member.MemberDefinition;
+				return mrr != null && findReferences.IsMemberMatch(method, mrr.Member, mrr.IsVirtualCall);
 			}
 			
 			internal override void NavigatorDone(CSharpAstResolver resolver, CancellationToken cancellationToken)
 			{
 				foreach (var expr in potentialMethodGroupConversions) {
 					var conversion = resolver.GetConversion(expr, cancellationToken);
-					if (conversion.IsMethodGroupConversion && conversion.Method.MemberDefinition == method) {
+					if (conversion.IsMethodGroupConversion && findReferences.IsMemberMatch(method, conversion.Method, conversion.IsVirtualMethodLookup)) {
 						IType targetType = resolver.GetExpectedType(expr, cancellationToken);
 						ResolveResult result = resolver.Resolve(expr, cancellationToken);
 						ReportMatch(expr, new ConversionResolveResult(targetType, result, conversion));
@@ -733,7 +817,6 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		#region Find Indexer References
 		SearchScope FindIndexerReferences(IProperty indexer)
 		{
-			indexer = (IProperty)indexer.MemberDefinition;
 			return new SearchScope(
 				delegate (ICompilation compilation) {
 					IProperty imported = compilation.Import(indexer);
@@ -761,7 +844,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				MemberResolveResult mrr = rr as MemberResolveResult;
-				return mrr != null && indexer == mrr.Member.MemberDefinition;
+				return mrr != null && findReferences.IsMemberMatch(indexer, mrr.Member, mrr.IsVirtualCall);
 			}
 		}
 		#endregion
@@ -834,7 +917,6 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		
 		SearchScope FindOperator(IMethod op, Func<IMethod, FindReferenceNavigator> factory)
 		{
-			op = (IMethod)op.MemberDefinition;
 			return new SearchScope(
 				delegate (ICompilation compilation) {
 					IMethod imported = compilation.Import(op);
@@ -875,7 +957,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				MemberResolveResult mrr = rr as MemberResolveResult;
-				return mrr != null && op == mrr.Member.MemberDefinition;
+				return mrr != null && findReferences.IsMemberMatch(op, mrr.Member, mrr.IsVirtualCall);
 			}
 		}
 		
@@ -907,7 +989,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				MemberResolveResult mrr = rr as MemberResolveResult;
-				return mrr != null && op == mrr.Member.MemberDefinition;
+				return mrr != null && findReferences.IsMemberMatch(op, mrr.Member, mrr.IsVirtualCall);
 			}
 		}
 		
@@ -928,12 +1010,12 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				MemberResolveResult mrr = rr as MemberResolveResult;
-				return mrr != null && op == mrr.Member.MemberDefinition;
+				return mrr != null && findReferences.IsMemberMatch(op, mrr.Member, mrr.IsVirtualCall);
 			}
 			
 			public override void ProcessConversion(Expression expression, ResolveResult result, Conversion conversion, IType targetType)
 			{
-				if (conversion.IsUserDefined && conversion.Method.MemberDefinition == op) {
+				if (conversion.IsUserDefined && findReferences.IsMemberMatch(op, conversion.Method, conversion.IsVirtualMethodLookup)) {
 					ReportMatch(expression, result);
 				}
 			}
@@ -956,7 +1038,8 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				ConversionResolveResult crr = rr as ConversionResolveResult;
-				return crr != null && crr.Conversion.IsUserDefined && crr.Conversion.Method.MemberDefinition == op;
+				return crr != null && crr.Conversion.IsUserDefined 
+					&& findReferences.IsMemberMatch(op, crr.Conversion.Method, crr.Conversion.IsVirtualMethodLookup);
 			}
 		}
 		#endregion
@@ -964,7 +1047,6 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		#region Find Constructor References
 		SearchScope FindObjectCreateReferences(IMethod ctor)
 		{
-			ctor = (IMethod)ctor.MemberDefinition;
 			string searchTerm = null;
 			if (KnownTypeReference.GetCSharpNameByTypeCode(ctor.DeclaringTypeDefinition.KnownTypeCode) == null) {
 				// not a built-in type
@@ -1002,13 +1084,12 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				MemberResolveResult mrr = rr as MemberResolveResult;
-				return mrr != null && ctor == mrr.Member.MemberDefinition;
+				return mrr != null && findReferences.IsMemberMatch(ctor, mrr.Member, mrr.IsVirtualCall);
 			}
 		}
 		
 		SearchScope FindChainedConstructorReferences(IMethod ctor)
 		{
-			ctor = (IMethod)ctor.MemberDefinition;
 			SearchScope searchScope = new SearchScope(
 				delegate (ICompilation compilation) {
 					IMethod imported = compilation.Import(ctor);
@@ -1042,7 +1123,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				MemberResolveResult mrr = rr as MemberResolveResult;
-				return mrr != null && ctor == mrr.Member.MemberDefinition;
+				return mrr != null && findReferences.IsMemberMatch(ctor, mrr.Member, mrr.IsVirtualCall);
 			}
 		}
 		#endregion
@@ -1050,22 +1131,17 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		#region Find Destructor References
 		SearchScope GetSearchScopeForDestructor(IMethod dtor)
 		{
-			dtor = (IMethod)dtor.MemberDefinition;
+			var scope = new SearchScope (
-			string searchTerm = null;
-			if (KnownTypeReference.GetCSharpNameByTypeCode(dtor.DeclaringTypeDefinition.KnownTypeCode) == null) {
-				// not a built-in type
-				searchTerm = dtor.DeclaringTypeDefinition.Name;
-			}
-			return new SearchScope (
-				searchTerm,
 				delegate (ICompilation compilation) {
-				IMethod imported = compilation.Import(dtor);
+					IMethod imported = compilation.Import(dtor);
-				if (imported != null) {
+					if (imported != null) {
-					return new FindDestructorReferencesNavigator (imported);
+						return new FindDestructorReferencesNavigator (imported);
-				} else {
+					} else {
-					return null;
+						return null;
-				}
+					}
-			});
+				});
+			scope.accessibility = Accessibility.Private;
+			return scope;
 		}
 		
 		sealed class FindDestructorReferencesNavigator : FindReferenceNavigator
@@ -1085,7 +1161,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			internal override bool IsMatch(ResolveResult rr)
 			{
 				MemberResolveResult mrr = rr as MemberResolveResult;
-				return mrr != null && dtor == mrr.Member.MemberDefinition;
+				return mrr != null && findReferences.IsMemberMatch(dtor, mrr.Member, mrr.IsVirtualCall);
 			}
 		}
 		#endregion

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Resolver/MethodGroupResolveResult.cs

@@ -164,7 +164,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 						this.TargetType, method, true, out inferredTypes))
 					{
 						if (substituteInferredTypes && inferredTypes != null) {
-							outputGroup.Add(new SpecializedMethod(method.DeclaringType, method, inferredTypes));
+							outputGroup.Add(new SpecializedMethod(method, new TypeParameterSubstitution(null, inferredTypes)));
 						} else {
 							outputGroup.Add(method);
 						}

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Resolver/OverloadResolution.cs

@@ -778,11 +778,20 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		{
 			if (bestCandidate == null)
 				return arguments;
+			else
+				return GetArgumentsWithConversions(null);
+		}
+		
+		IList<ResolveResult> GetArgumentsWithConversions(ResolveResult targetResolveResult)
+		{
 			var conversions = this.ArgumentConversions;
 			ResolveResult[] args = new ResolveResult[arguments.Length];
 			for (int i = 0; i < args.Length; i++) {
+				var argument = arguments[i];
+				if (this.IsExtensionMethodInvocation && i == 0 && targetResolveResult != null)
+					argument = targetResolveResult;
 				if (conversions[i] == Conversion.IdentityConversion) {
-					args[i] = arguments[i];
+					args[i] = argument;
 				} else {
 					int parameterIndex = bestCandidate.ArgumentToParameterMap[i];
 					IType parameterType;
@@ -792,9 +801,9 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 						parameterType = SpecialType.UnknownType;
 					}
 					if (arguments[i].IsCompileTimeConstant && conversions[i] != Conversion.None) {
-						args[i] = new CSharpResolver(compilation).ResolveCast(parameterType, arguments[i]);
+						args[i] = new CSharpResolver(compilation).ResolveCast(parameterType, argument);
 					} else {
-						args[i] = new ConversionResolveResult(parameterType, arguments[i], conversions[i]);
+						args[i] = new ConversionResolveResult(parameterType, argument, conversions[i]);
 					}
 				}
 			}
@@ -807,7 +816,16 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				return null;
 			IMethod method = bestCandidate.Member as IMethod;
 			if (method != null && method.TypeParameters.Count > 0) {
-				return new SpecializedMethod(method.DeclaringType, (IMethod)method.MemberDefinition, bestCandidate.InferredTypes);
+				SpecializedMethod sm = method as SpecializedMethod;
+				if (sm != null) {
+					// Do not compose the substitutions, but merge them.
+					// This is required for InvocationTests.SubstituteClassAndMethodTypeParametersAtOnce
+					return new SpecializedMethod(
+						(IMethod)method.MemberDefinition,
+						new TypeParameterSubstitution(sm.Substitution.ClassTypeArguments, bestCandidate.InferredTypes));
+				} else {
+					return new SpecializedMethod(method, new TypeParameterSubstitution(null, bestCandidate.InferredTypes));
+				}
 			} else {
 				return bestCandidate.Member;
 			}
@@ -830,9 +848,9 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				throw new InvalidOperationException();
 			
 			return new CSharpInvocationResolveResult(
-				targetResolveResult,
+				this.IsExtensionMethodInvocation ? new TypeResolveResult(member.DeclaringType) : targetResolveResult,
 				member,
-				GetArgumentsWithConversions(),
+				GetArgumentsWithConversions(targetResolveResult),
 				this.BestCandidateErrors,
 				this.IsExtensionMethodInvocation,
 				this.BestCandidateIsExpandedForm,

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Resolver/ResolveVisitor.cs

@@ -650,7 +650,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				ResolveResult result = errorResult;
 				if (variableInitializer.Parent is FieldDeclaration || variableInitializer.Parent is EventDeclaration) {
 					if (resolver.CurrentMember != null) {
-						result = new MemberResolveResult(null, resolver.CurrentMember);
+						result = new MemberResolveResult(null, resolver.CurrentMember, false);
 					}
 				} else {
 					string identifier = variableInitializer.Name;
@@ -707,7 +707,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			if (resolverEnabled) {
 				ResolveResult result = errorResult;
 				if (resolver.CurrentMember != null) {
-					result = new MemberResolveResult(null, resolver.CurrentMember);
+					result = new MemberResolveResult(null, resolver.CurrentMember, false);
 				}
 				ResolveAndProcessConversion(fixedVariableInitializer.CountExpression, resolver.Compilation.FindType(KnownTypeCode.Int32));
 				return result;
@@ -726,7 +726,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				ScanChildren(member);
 				
 				if (resolver.CurrentMember != null)
-					return new MemberResolveResult(null, resolver.CurrentMember);
+					return new MemberResolveResult(null, resolver.CurrentMember, false);
 				else
 					return errorResult;
 			} finally {
@@ -772,7 +772,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 					}
 				}
 				if (resolver.CurrentMember != null)
-					return new MemberResolveResult(null, resolver.CurrentMember);
+					return new MemberResolveResult(null, resolver.CurrentMember, false);
 				else
 					return errorResult;
 			} finally {
@@ -805,7 +805,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				}
 				
 				if (resolver.CurrentMember != null)
-					return new MemberResolveResult(null, resolver.CurrentMember);
+					return new MemberResolveResult(null, resolver.CurrentMember, false);
 				else
 					return errorResult;
 			} finally {
@@ -885,7 +885,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				if (resolverEnabled && resolver.CurrentTypeDefinition != null) {
 					ResolveAndProcessConversion(enumMemberDeclaration.Initializer, resolver.CurrentTypeDefinition.EnumUnderlyingType);
 					if (resolverEnabled && resolver.CurrentMember != null)
-						return new MemberResolveResult(null, resolver.CurrentMember);
+						return new MemberResolveResult(null, resolver.CurrentMember, false);
 					else
 						return errorResult;
 				} else {
@@ -1310,8 +1310,10 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		{
 			if (resolverEnabled || !objectCreateExpression.Initializer.IsNull) {
 				var typeResolveResult = Resolve(objectCreateExpression.Type);
-				if (typeResolveResult.IsError)
+				if (typeResolveResult.IsError) {
+					ScanChildren (objectCreateExpression);
 					return typeResolveResult;
+				}
 				IType type = typeResolveResult.Type;
 				
 				List<ResolveResult> initializerStatements = null;

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp/Resolver/TypeInference.cs

@@ -629,15 +629,12 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			// Handle array types:
 			ArrayType arrU = U as ArrayType;
 			ArrayType arrV = V as ArrayType;
-			ParameterizedType pV = V as ParameterizedType;
 			if (arrU != null && arrV != null && arrU.Dimensions == arrV.Dimensions) {
 				MakeLowerBoundInference(arrU.ElementType, arrV.ElementType);
 				return;
-			} else if (arrU != null && IsIEnumerableCollectionOrList(pV) && arrU.Dimensions == 1) {
-				MakeLowerBoundInference(arrU.ElementType, pV.GetTypeArgument(0));
-				return;
 			}
 			// Handle parameterized types:
+			ParameterizedType pV = V as ParameterizedType;
 			if (pV != null) {
 				ParameterizedType uniqueBaseType = null;
 				foreach (IType baseU in U.GetAllBaseTypes()) {
@@ -677,20 +674,6 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				Log.Unindent();
 			}
 		}
-		
-		static bool IsIEnumerableCollectionOrList(ParameterizedType rt)
-		{
-			if (rt == null || rt.TypeParameterCount != 1)
-				return false;
-			switch (rt.GetDefinition().FullName) {
-				case "System.Collections.Generic.IList":
-				case "System.Collections.Generic.ICollection":
-				case "System.Collections.Generic.IEnumerable":
-					return true;
-				default:
-					return false;
-			}
-		}
 		#endregion
 		
 		#region MakeUpperBoundInference (§7.5.2.10)
@@ -713,15 +696,12 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			// Handle array types:
 			ArrayType arrU = U as ArrayType;
 			ArrayType arrV = V as ArrayType;
-			ParameterizedType pU = U as ParameterizedType;
 			if (arrV != null && arrU != null && arrU.Dimensions == arrV.Dimensions) {
 				MakeUpperBoundInference(arrU.ElementType, arrV.ElementType);
 				return;
-			} else if (arrV != null && IsIEnumerableCollectionOrList(pU) && arrV.Dimensions == 1) {
-				MakeUpperBoundInference(pU.GetTypeArgument(0), arrV.ElementType);
-				return;
 			}
 			// Handle parameterized types:
+			ParameterizedType pU = U as ParameterizedType;
 			if (pU != null) {
 				ParameterizedType uniqueBaseType = null;
 				foreach (IType baseV in V.GetAllBaseTypes()) {

src/Libraries/NRefactory/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/CodeCompletionBugTests.cs

@@ -4789,5 +4789,27 @@ class B : A
 			Assert.AreEqual (2, provider.Data.Where (d => d.DisplayText == "Method").Count ());
 		}
 
+		/// <summary>
+		/// Bug 3973 - code completion forgets context if text is deleted 
+		/// </summary>
+		[Test()]
+		public void TestBug3973 ()
+		{
+			var provider = CreateProvider (
+@"
+using System;
+
+class A
+{
+	public static void Main (string[] args)
+	{
+		Console.$W$
+	}
+}
+
+");
+			Assert.IsNotNull (provider.Find ("WriteLine"), "'WriteLine' not found.");
+		}
+
 	}
 }

src/Libraries/NRefactory/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/NameContextTests.cs

@@ -122,6 +122,19 @@ namespace ICSharpCode.NRefactory.CSharp.CodeCompletion
 			Assert.IsTrue (provider == null || provider.Count == 0, "provider should be empty.");
 		}
 
+		[Test()]
+		public void TestForLoopLocalVariableName ()
+		{
+
+			var provider = CodeCompletionBugTests.CreateProvider (@"class MyClass {
+	void Test() 
+	{
+		$for (int f$
+	}
+}");
+			Assert.IsTrue (provider == null || provider.Count == 0, "provider should be empty.");
+		}
+
 		[Test()]
 		public void TestCatchExceptionName ()
 		{

src/Libraries/NRefactory/ICSharpCode.NRefactory.Tests/CSharp/ContextAction/ConvertForeachToForTests.cs

@@ -1,4 +1,4 @@
-// 
+// 
 // ConvertForeachToForTests.cs
 //  
 // Author:
@@ -64,7 +64,7 @@ namespace ICSharpCode.NRefactory.CSharp.ContextActions
 		}
 		
 		[Test()]
-		public void TestEnumeration ()
+		public void TestListOfT ()
 		{
 			string result = RunContextAction (
 				new ConvertForeachToFor (),
@@ -95,5 +95,24 @@ namespace ICSharpCode.NRefactory.CSharp.ContextActions
 				"	}" + Environment.NewLine +
 				"}", result);
 		}
+		
+		[Test()]
+		public void TestEnumerableOfT ()
+		{
+			TestWrongContext (
+				new ConvertForeachToFor (),
+				"using System;" + Environment.NewLine +
+				"using System.Collections.Generic;" + Environment.NewLine +
+				"class TestClass" + Environment.NewLine +
+				"{" + Environment.NewLine +
+				"	void Test (IEnumerable<string> args)" + Environment.NewLine +
+				"	{" + Environment.NewLine +
+				"		$foreach (var v in args) {" + Environment.NewLine +
+				"			Console.WriteLine (v);" + Environment.NewLine +
+				"		}" + Environment.NewLine +
+				"	}" + Environment.NewLine +
+				"}"
+			);
+		}
 	}
 }

src/Libraries/NRefactory/ICSharpCode.NRefactory.Tests/CSharp/Resolver/FindReferencesTest.cs

@@ -33,24 +33,26 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		CompilationUnit compilationUnit;
 		CSharpParsedFile parsedFile;
 		ICompilation compilation;
+		FindReferences findReferences;
 		
 		void Init(string code)
 		{
 			compilationUnit = new CSharpParser().Parse(new StringReader(code), "test.cs");
 			parsedFile = compilationUnit.ToTypeSystem();
 			compilation = TypeSystemHelper.CreateCompilation(parsedFile);
+			findReferences = new FindReferences();
 		}
 		
 		AstNode[] FindReferences(IEntity entity)
 		{
 			var result = new List<AstNode>();
-			var findReferences = new FindReferences();
 			var searchScopes = findReferences.GetSearchScopes(entity);
 			findReferences.FindReferencesInFile(searchScopes, parsedFile, compilationUnit, compilation,
 			                                    (node, rr) => result.Add(node), CancellationToken.None);
 			return result.OrderBy(n => n.StartLocation).ToArray();
 		}
 		
+		#region Method Group
 		[Test]
 		public void FindMethodGroupReference()
 		{
@@ -107,7 +109,9 @@ class Test {
 			Assert.AreEqual(new [] { new TextLocation(4, 49), new TextLocation(7, 2) },
 			                FindReferences(m_string).Select(n => n.StartLocation).ToArray());
 		}
+		#endregion
 		
+		#region GetEnumerator
 		[Test]
 		public void FindReferenceToGetEnumeratorUsedImplicitlyInForeach()
 		{
@@ -129,7 +133,9 @@ class Test {
 			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 3 && r is MethodDeclaration));
 			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 8 && r is ForeachStatement));
 		}
+		#endregion
 		
+		#region Op_Implicit
 		[Test]
 		public void FindReferencesForOpImplicitInLocalVariableInitialization()
 		{
@@ -147,5 +153,63 @@ class Test {
 			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 4 && r is ObjectCreateExpression));
 			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 6 && r is OperatorDeclaration));
 		}
+		#endregion
+		
+		#region Inheritance
+		const string inheritanceTest = @"using System;
+class A { public virtual void M() {} }
+class B : A { public override void M() {} }
+class C : A { public override void M() {} }
+class Calls {
+	void Test(A a, B b, C c) {
+		a.M();
+		b.M();
+		c.M();
+	}
+}";
+		
+		[Test]
+		public void InheritanceTest1()
+		{
+			Init(inheritanceTest);
+			var test = compilation.MainAssembly.TopLevelTypeDefinitions.Single(t => t.Name == "B");
+			var BM = test.Methods.Single(m => m.Name == "M");
+			var actual = FindReferences(BM).ToList();
+			Assert.AreEqual(2, actual.Count);
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 3 && r is MethodDeclaration));
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 8 && r is InvocationExpression));
+		}
+		
+		[Test]
+		public void InheritanceTest2()
+		{
+			Init(inheritanceTest);
+			findReferences.FindCallsThroughVirtualBaseMethod = true;
+			var test = compilation.MainAssembly.TopLevelTypeDefinitions.Single(t => t.Name == "B");
+			var BM = test.Methods.Single(m => m.Name == "M");
+			var actual = FindReferences(BM).ToList();
+			Assert.AreEqual(3, actual.Count);
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 3 && r is MethodDeclaration));
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 7 && r is InvocationExpression));
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 8 && r is InvocationExpression));
+		}
+		
+		[Test]
+		public void InheritanceTest3()
+		{
+			Init(inheritanceTest);
+			findReferences.WholeVirtualSlot = true;
+			var test = compilation.MainAssembly.TopLevelTypeDefinitions.Single(t => t.Name == "B");
+			var BM = test.Methods.Single(m => m.Name == "M");
+			var actual = FindReferences(BM).ToList();
+			Assert.AreEqual(6, actual.Count);
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 2 && r is MethodDeclaration));
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 3 && r is MethodDeclaration));
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 4 && r is MethodDeclaration));
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 7 && r is InvocationExpression));
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 8 && r is InvocationExpression));
+			Assert.IsTrue(actual.Any(r => r.StartLocation.Line == 9 && r is InvocationExpression));
+		}
+		#endregion
 	}
 }

src/Libraries/NRefactory/ICSharpCode.NRefactory.Tests/CSharp/Resolver/InvocationTests.cs

@@ -493,5 +493,33 @@ class Test : IVisitor<object, object> {
 			Assert.AreEqual("System.Object", typeArguments[0].ReflectionName);
 			Assert.AreEqual("System.Object", typeArguments[1].ReflectionName);
 		}
+		
+		[Test]
+		public void FirstParameterToExtensionMethod()
+		{
+			string program = @"
+public class X {}
+public static class Ex {
+	public static void F(this X x, int y, int z) {}
+}
+class C {
+	public void M() {
+		X a = null;
+		int b = 0, c = 0;
+		$a.F(b, c)$;
+	}
+}";
+			var rr = Resolve<CSharpInvocationResolveResult>(program);
+			Assert.IsFalse(rr.IsError);
+			Assert.That(rr.IsExtensionMethodInvocation, Is.True);
+			Assert.That(rr.Arguments[0], Is.InstanceOf<LocalResolveResult>());
+			Assert.That(((LocalResolveResult)rr.Arguments[0]).Variable.Name, Is.EqualTo("a"));
+			Assert.That(rr.Arguments[1], Is.InstanceOf<LocalResolveResult>());
+			Assert.That(((LocalResolveResult)rr.Arguments[1]).Variable.Name, Is.EqualTo("b"));
+			Assert.That(rr.Arguments[2], Is.InstanceOf<LocalResolveResult>());
+			Assert.That(((LocalResolveResult)rr.Arguments[2]).Variable.Name, Is.EqualTo("c"));
+			
+			Assert.That(rr.TargetResult, Is.InstanceOf<TypeResolveResult>());
+		}
 	}
 }

src/Libraries/NRefactory/ICSharpCode.NRefactory.Tests/CSharp/Resolver/ObjectCreationTests.cs

@@ -260,5 +260,18 @@ class Test {
 			Assert.AreEqual("Test", rr.Type.ReflectionName);
 			Assert.AreEqual(5, rr.InitializerStatements.Count);
 		}
+		
+		[Test]
+		public void CreateGeneric()
+		{
+			string program = @"using System;
+class Test<T> where T : new() {
+	object x = $new T()$;
+}";
+			var rr = Resolve<CSharpInvocationResolveResult>(program);
+			Assert.IsFalse(rr.IsError);
+			Assert.AreEqual(TypeKind.TypeParameter, rr.Type.Kind);
+			Assert.AreEqual(TypeKind.TypeParameter, rr.Member.DeclaringType.Kind);
+		}
 	}
 }

src/Libraries/NRefactory/ICSharpCode.NRefactory.Tests/CSharp/Resolver/TypeInferenceTests.cs

@@ -70,6 +70,25 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			Assert.IsTrue(success);
 		}
 		
+		[Test]
+		public void ArrayToReadOnlyList()
+		{
+			ITypeParameter tp = new DefaultTypeParameter(compilation, EntityType.Method, 0, "T");
+			IType stringType = compilation.FindType(KnownTypeCode.String);
+			ITypeDefinition readOnlyListType = compilation.FindType(KnownTypeCode.IReadOnlyListOfT).GetDefinition();
+			if (readOnlyListType == null)
+				Assert.Ignore(".NET 4.5 IReadOnlyList not available");
+			
+			bool success;
+			Assert.AreEqual(
+				new [] { stringType },
+				ti.InferTypeArguments(new [] { tp },
+				                      new [] { new ResolveResult(new ArrayType(compilation, stringType)) },
+				                      new [] { new ParameterizedType(readOnlyListType, new [] { tp }) },
+				                      out success));
+			Assert.IsTrue(success);
+		}
+		
 		[Test]
 		public void EnumerableToArrayInContravariantType()
 		{

src/Libraries/NRefactory/ICSharpCode.NRefactory.Tests/TypeSystem/TypeSystemTests.cs

@@ -182,6 +182,7 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			IMethod m = testClass.Methods.Single(me => me.Name == "GetIndex");
 			Assert.AreEqual("T", m.TypeParameters[0].Name);
 			Assert.AreEqual(EntityType.Method, m.TypeParameters[0].OwnerType);
+			Assert.AreSame(m, m.TypeParameters[0].Owner);
 			
 			ParameterizedType constraint = (ParameterizedType)m.TypeParameters[0].DirectBaseTypes.First();
 			Assert.AreEqual("IEquatable", constraint.Name);
@@ -190,6 +191,53 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			Assert.AreSame(m.TypeParameters[0], constraint.TypeArguments[0]);
 		}
 		
+		[Test]
+		public void GetIndexSpecializedTypeParameter()
+		{
+			var testClass = GetTypeDefinition(typeof(GenericClass<,>));
+			var methodDef = testClass.Methods.Single(me => me.Name == "GetIndex");
+			var m = new SpecializedMethod(methodDef, new TypeParameterSubstitution(
+				new[] { compilation.FindType(KnownTypeCode.Int16), compilation.FindType(KnownTypeCode.Int32) },
+				null
+			));
+			
+			Assert.AreEqual("T", m.TypeParameters[0].Name);
+			Assert.AreEqual(EntityType.Method, m.TypeParameters[0].OwnerType);
+			Assert.AreSame(m, m.TypeParameters[0].Owner);
+			
+			ParameterizedType constraint = (ParameterizedType)m.TypeParameters[0].DirectBaseTypes.First();
+			Assert.AreEqual("IEquatable", constraint.Name);
+			Assert.AreEqual(1, constraint.TypeParameterCount);
+			Assert.AreEqual(1, constraint.TypeArguments.Count);
+			Assert.AreSame(m.TypeParameters[0], constraint.TypeArguments[0]);
+		}
+		
+		[Test]
+		public void GetIndexDoubleSpecialization()
+		{
+			var testClass = GetTypeDefinition(typeof(GenericClass<,>));
+			// GenericClass<A, B>.GetIndex<T>
+			var methodDef = testClass.Methods.Single(me => me.Name == "GetIndex");
+			
+			// GenericClass<B, A>.GetIndex<A>
+			var m1 = new SpecializedMethod(methodDef, new TypeParameterSubstitution(
+				new[] { testClass.TypeParameters[1], testClass.TypeParameters[0] },
+				new[] { testClass.TypeParameters[0] }
+			));
+			// GenericClass<string, int>.GetIndex<int>
+			var m2 = new SpecializedMethod(m1, new TypeParameterSubstitution(
+				new[] { compilation.FindType(KnownTypeCode.Int32), compilation.FindType(KnownTypeCode.String) },
+				null
+			));
+			
+			// GenericClass<string, int>.GetIndex<int>
+			var m12 = new SpecializedMethod(methodDef, new TypeParameterSubstitution(
+				new[] { compilation.FindType(KnownTypeCode.String), compilation.FindType(KnownTypeCode.Int32) },
+				new[] { compilation.FindType(KnownTypeCode.Int32) }
+			));
+			Assert.AreEqual(m12, m2);
+		}
+		
 		[Test]
 		public void GenericEnum()
 		{

src/Libraries/NRefactory/ICSharpCode.NRefactory/Documentation/IdStringProvider.cs

@@ -31,7 +31,7 @@ namespace ICSharpCode.NRefactory.Documentation
 	/// </summary>
 	public static class IdStringProvider
 	{
-		#region GetIDString
+		#region GetIdString
 		/// <summary>
 		/// Gets the ID string (C# 4.0 spec, §A.3.1) for the specified entity.
 		/// </summary>

src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/ITextSource.cs

@@ -168,7 +168,7 @@ namespace ICSharpCode.NRefactory.Editor
 	/// <remarks>
 	/// Verions can be used to efficiently detect whether a document has changed and needs reparsing;
 	/// or even to implement incremental parsers.
-	/// It is a separate class from ITextBuffer to allow the GC to collect the text buffer while
+	/// It is a separate class from ITextSource to allow the GC to collect the text source while
 	/// the version checkpoint is still in use.
 	/// </remarks>
 	public interface ITextSourceVersion

src/Libraries/NRefactory/ICSharpCode.NRefactory/Semantics/Conversion.cs

@@ -88,11 +88,11 @@ namespace ICSharpCode.NRefactory.Semantics
 			return new UserDefinedConversion(false, operatorMethod, isLifted);
 		}
 		
-		public static Conversion MethodGroupConversion(IMethod chosenMethod)
+		public static Conversion MethodGroupConversion(IMethod chosenMethod, bool isVirtualMethodLookup)
 		{
 			if (chosenMethod == null)
 				throw new ArgumentNullException("chosenMethod");
-			return new MethodGroupConv(chosenMethod);
+			return new MethodGroupConv(chosenMethod, isVirtualMethodLookup);
 		}
 		#endregion
 		
@@ -302,10 +302,12 @@ namespace ICSharpCode.NRefactory.Semantics
 		sealed class MethodGroupConv : Conversion
 		{
 			readonly IMethod method;
+			readonly bool isVirtualMethodLookup;
 			
-			public MethodGroupConv(IMethod method)
+			public MethodGroupConv(IMethod method, bool isVirtualMethodLookup)
 			{
 				this.method = method;
+				this.isVirtualMethodLookup = isVirtualMethodLookup;
 			}
 			
 			public override bool IsImplicit {
@@ -316,6 +318,10 @@ namespace ICSharpCode.NRefactory.Semantics
 				get { return true; }
 			}
 			
+			public override bool IsVirtualMethodLookup {
+				get { return isVirtualMethodLookup; }
+			}
+			
 			public override IMethod Method {
 				get { return method; }
 			}
@@ -434,6 +440,13 @@ namespace ICSharpCode.NRefactory.Semantics
 			get { return false; }
 		}
 		
+		/// <summary>
+		/// For method-group conversions, gets whether to perform a virtual method lookup at runtime.
+		/// </summary>
+		public virtual bool IsVirtualMethodLookup {
+			get { return false; }
+		}
+		
 		/// <summary>
 		/// Gets whether this conversion is an anonymous function conversion.
 		/// </summary>

src/Libraries/NRefactory/ICSharpCode.NRefactory/Semantics/MemberResolveResult.cs

@@ -34,12 +34,30 @@ namespace ICSharpCode.NRefactory.Semantics
 		readonly bool isConstant;
 		readonly object constantValue;
 		readonly ResolveResult targetResult;
+		readonly bool isVirtualCall;
 		
 		public MemberResolveResult(ResolveResult targetResult, IMember member)
 			: base(member.EntityType == EntityType.Constructor ? member.DeclaringType : member.ReturnType)
 		{
 			this.targetResult = targetResult;
 			this.member = member;
+			var thisRR = targetResult as ThisResolveResult;
+			this.isVirtualCall = member.IsOverridable && !(thisRR != null && thisRR.CausesNonVirtualInvocation);
+			
+			IField field = member as IField;
+			if (field != null) {
+				isConstant = field.IsConst;
+				if (isConstant)
+					constantValue = field.ConstantValue;
+			}
+		}
+		
+		public MemberResolveResult(ResolveResult targetResult, IMember member, bool isVirtualCall)
+			: base(member.EntityType == EntityType.Constructor ? member.DeclaringType : member.ReturnType)
+		{
+			this.targetResult = targetResult;
+			this.member = member;
+			this.isVirtualCall = isVirtualCall;
 			IField field = member as IField;
 			if (field != null) {
 				isConstant = field.IsConst;
@@ -69,6 +87,13 @@ namespace ICSharpCode.NRefactory.Semantics
 			get { return member; }
 		}
 		
+		/// <summary>
+		/// Gets whether this MemberResolveResult is a virtual call.
+		/// </summary>
+		public bool IsVirtualCall {
+			get { return isVirtualCall; }
+		}
+		
 		public override bool IsCompileTimeConstant {
 			get { return isConstant; }
 		}

src/Libraries/NRefactory/ICSharpCode.NRefactory/Semantics/ThisResolveResult.cs

@@ -27,8 +27,18 @@ namespace ICSharpCode.NRefactory.Semantics
 	/// </summary>
 	public class ThisResolveResult : ResolveResult
 	{
-		public ThisResolveResult(IType type) : base(type)
+		bool causesNonVirtualInvocation;
+		
+		public ThisResolveResult(IType type, bool causesNonVirtualInvocation = false) : base(type)
 		{
+			this.causesNonVirtualInvocation = causesNonVirtualInvocation;
+		}
+		
+		/// <summary>
+		/// Gets whether this resolve result causes member invocations to be non-virtual.
+		/// </summary>
+		public bool CausesNonVirtualInvocation {
+			get { return causesNonVirtualInvocation; }
 		}
 	}
 }

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/ExtensionMethods.cs

@@ -246,19 +246,10 @@ namespace ICSharpCode.NRefactory.TypeSystem
 		{
 			if (type == null)
 				throw new ArgumentNullException("type");
-			ITypeDefinition def = type.GetDefinition();
+			if (type.Kind == TypeKind.Delegate)
-			if (def != null && def.Kind == TypeKind.Delegate) {
+				return type.GetMethods(m => m.Name == "Invoke", GetMemberOptions.IgnoreInheritedMembers).FirstOrDefault();
-				foreach (IMember member in def.Members) {
+			else
-					if (member.Name == "Invoke" && member is IMethod) {
+				return null;
-						ParameterizedType pt = type as ParameterizedType;
-						if (pt != null) {
-							return new SpecializedMethod(pt, (IMethod)member);
-						}
-						return (IMethod)member;
-					}
-				}
-			}
-			return null;
 		}
 		#endregion
 		

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/IMember.cs

@@ -20,6 +20,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics.Contracts;
 using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.NRefactory.TypeSystem.Implementation;
 
 namespace ICSharpCode.NRefactory.TypeSystem
 {

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/AbstractResolvedMember.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using ICSharpCode.NRefactory.Documentation;
 using ICSharpCode.NRefactory.Utils;
 
@@ -65,18 +66,6 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			}
 		}
 		
-		public override DocumentationComment Documentation {
-			get {
-				IUnresolvedDocumentationProvider docProvider = unresolved.ParsedFile as IUnresolvedDocumentationProvider;
-				if (docProvider != null) {
-					var doc = docProvider.GetDocumentation(unresolved, this);
-					if (doc != null)
-						return doc;
-				}
-				return base.Documentation;
-			}
-		}
-		
 		IList<IMember> FindImplementedInterfaceMembers()
 		{
 			if (unresolved.IsExplicitInterfaceImplementation) {
@@ -87,8 +76,25 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 						result.Add(member);
 				}
 				return result.ToArray();
+			} else if (unresolved.IsStatic) {
+				return EmptyList<IMember>.Instance;
 			} else {
-				throw new NotImplementedException();
+				// TODO: implement interface member mappings correctly
+				return InheritanceHelper.GetBaseMembers(this, true)
+					.Where(m => m.DeclaringTypeDefinition != null && m.DeclaringTypeDefinition.Kind == TypeKind.Interface)
+					.ToArray();
+			}
+		}
+		
+		public override DocumentationComment Documentation {
+			get {
+				IUnresolvedDocumentationProvider docProvider = unresolved.ParsedFile as IUnresolvedDocumentationProvider;
+				if (docProvider != null) {
+					var doc = docProvider.GetDocumentation(unresolved, this);
+					if (doc != null)
+						return doc;
+				}
+				return base.Documentation;
 			}
 		}
 		

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/AbstractResolvedTypeParameter.cs

@@ -261,7 +261,7 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 				if (this.HasDefaultConstructorConstraint || this.HasValueTypeConstraint) {
 					if (filter == null || filter(dummyConstructor)) {
 						var resolvedCtor = GetDummyConstructor(compilation);
-						IMethod m = new SpecializedMethod(this, resolvedCtor, EmptyList<IType>.Instance);
+						IMethod m = new SpecializedMethod(resolvedCtor, TypeParameterSubstitution.Identity) { DeclaringType = this };
 						return new [] { m };
 					}
 				}

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/DefaultResolvedTypeDefinition.cs

@@ -781,7 +781,8 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 				IType coClass = ComHelper.GetCoClass(this);
 				using (var busyLock = BusyManager.Enter(this)) {
 					if (busyLock.Success) {
-						return coClass.GetConstructors(filter, options).Select(m => new SpecializedMethod(this, m));
+						return coClass.GetConstructors(filter, options)
+							.Select(m => new SpecializedMethod(m, TypeParameterSubstitution.Identity) { DeclaringType = this });
 					}
 				}
 				return EmptyList<IMethod>.Instance;

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/GetMembersHelper.cs

@@ -132,7 +132,7 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 						else
 							substitution = new TypeParameterSubstitution(null, methodTypeArguments);
 					}
-					yield return new SpecializedMethod(baseType, m, methodTypeArguments, substitution);
+					yield return new SpecializedMethod(m, substitution);
 				}
 			} else {
 				foreach (IMethod m in declaredMethods) {
@@ -162,7 +162,7 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			ParameterizedType pt = baseType as ParameterizedType;
 			if (pt != null) {
 				var substitution = pt.GetSubstitution();
-				return declaredCtors.Select(m => new SpecializedMethod(pt, m, null, substitution));
+				return declaredCtors.Select(m => new SpecializedMethod(m, substitution) { DeclaringType = pt });
 			} else {
 				return declaredCtors;
 			}
@@ -189,7 +189,7 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			ParameterizedType pt = baseType as ParameterizedType;
 			if (pt != null) {
 				var substitution = pt.GetSubstitution();
-				return declaredProperties.Select(m => new SpecializedProperty(pt, m, substitution));
+				return declaredProperties.Select(m => new SpecializedProperty(m, substitution) { DeclaringType = pt });
 			} else {
 				return declaredProperties;
 			}
@@ -216,7 +216,7 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			ParameterizedType pt = baseType as ParameterizedType;
 			if (pt != null) {
 				var substitution = pt.GetSubstitution();
-				return declaredFields.Select(m => new SpecializedField(pt, m, substitution));
+				return declaredFields.Select(m => new SpecializedField(m, substitution) { DeclaringType = pt });
 			} else {
 				return declaredFields;
 			}
@@ -243,7 +243,7 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			ParameterizedType pt = baseType as ParameterizedType;
 			if (pt != null) {
 				var substitution = pt.GetSubstitution();
-				return declaredEvents.Select(m => new SpecializedEvent(pt, m, substitution));
+				return declaredEvents.Select(m => new SpecializedEvent(m, substitution) { DeclaringType = pt });
 			} else {
 				return declaredEvents;
 			}

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/SpecializedEvent.cs

@@ -27,18 +27,11 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 	{
 		readonly IEvent eventDefinition;
 		
-		public SpecializedEvent(IType declaringType, IEvent eventDefinition)
+		public SpecializedEvent(IEvent eventDefinition, TypeParameterSubstitution substitution)
-			: base(declaringType, eventDefinition)
+			: base(eventDefinition)
 		{
-			this.eventDefinition = eventDefinition;
+			AddSubstitution(substitution);
-			Initialize(GetSubstitution(declaringType));
+			this.eventDefinition = (IEvent)base.MemberDefinition;
-		}
-		
-		internal SpecializedEvent(IType declaringType, IEvent eventDefinition, TypeVisitor substitution)
-			: base(declaringType, eventDefinition)
-		{
-			this.eventDefinition = eventDefinition;
-			Initialize(substitution);
 		}
 		
 		public bool CanAdd {
@@ -53,16 +46,18 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			get { return eventDefinition.CanInvoke; }
 		}
 		
+		IMethod addAccessor, removeAccessor, invokeAccessor;
+		
 		public IMethod AddAccessor {
-			get { return WrapAccessor(eventDefinition.AddAccessor); }
+			get { return WrapAccessor(ref this.addAccessor, eventDefinition.AddAccessor); }
 		}
 		
 		public IMethod RemoveAccessor {
-			get { return WrapAccessor(eventDefinition.RemoveAccessor); }
+			get { return WrapAccessor(ref this.removeAccessor, eventDefinition.RemoveAccessor); }
 		}
 		
 		public IMethod InvokeAccessor {
-			get { return WrapAccessor(eventDefinition.InvokeAccessor); }
+			get { return WrapAccessor(ref this.invokeAccessor, eventDefinition.InvokeAccessor); }
 		}
 	}
 }

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/SpecializedField.cs

@@ -27,18 +27,11 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 	{
 		readonly IField fieldDefinition;
 		
-		public SpecializedField(IType declaringType, IField fieldDefinition)
+		public SpecializedField(IField fieldDefinition, TypeParameterSubstitution substitution)
-			: base(declaringType, fieldDefinition)
+			: base(fieldDefinition)
 		{
-			this.fieldDefinition = fieldDefinition;
+			AddSubstitution(substitution);
-			Initialize(GetSubstitution(declaringType));
+			this.fieldDefinition = (IField)base.MemberDefinition;
-		}
-		
-		internal SpecializedField(IType declaringType, IField fieldDefinition, TypeVisitor substitution)
-			: base(declaringType, fieldDefinition)
-		{
-			this.fieldDefinition = fieldDefinition;
-			Initialize(substitution);
 		}
 		
 		public bool IsReadOnly {

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/SpecializedMember.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Text;
 using System.Threading;
@@ -31,58 +32,115 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 	/// </summary>
 	public abstract class SpecializedMember : IMember
 	{
-		readonly IType declaringType;
 		readonly IMember memberDefinition;
+		TypeParameterSubstitution substitution;
+		
+		IType declaringType;
 		IType returnType;
 		
-		protected SpecializedMember(IType declaringType, IMember memberDefinition)
+		protected SpecializedMember(IMember memberDefinition)
 		{
-			if (declaringType == null)
-				throw new ArgumentNullException("declaringType");
 			if (memberDefinition == null)
 				throw new ArgumentNullException("memberDefinition");
 			
-			this.declaringType = declaringType;
+			SpecializedMember sm = memberDefinition as SpecializedMember;
-			this.memberDefinition = memberDefinition;
+			if (sm != null) {
+				this.memberDefinition = sm.memberDefinition;
+				this.substitution = sm.substitution;
+			} else {
+				this.memberDefinition = memberDefinition;
+				this.substitution = TypeParameterSubstitution.Identity;
+			}
 		}
 		
-		protected virtual void Initialize(TypeVisitor substitution)
+		/// <summary>
+		/// Performs a substitution. This method may only be called by constructors in derived classes.
+		/// </summary>
+		protected void AddSubstitution(TypeParameterSubstitution newSubstitution)
 		{
-			this.returnType = Substitute(memberDefinition.ReturnType, substitution);
+			Debug.Assert(declaringType == null);
+			Debug.Assert(returnType == null);
+			this.substitution = TypeParameterSubstitution.Compose(newSubstitution, this.substitution);
 		}
 		
-		public virtual IMemberReference ToMemberReference()
+		public static SpecializedMember Create(IMember memberDefinition, TypeParameterSubstitution substitution)
 		{
-			return new SpecializingMemberReference(declaringType.ToTypeReference(), memberDefinition.ToMemberReference());
+			if (memberDefinition == null) {
+				return null;
+			} else if (memberDefinition is IMethod) {
+				return new SpecializedMethod((IMethod)memberDefinition, substitution);
+			} else if (memberDefinition is IProperty) {
+				return new SpecializedProperty((IProperty)memberDefinition, substitution);
+			} else if (memberDefinition is IField) {
+				return new SpecializedField((IField)memberDefinition, substitution);
+			} else if (memberDefinition is IEvent) {
+				return new SpecializedEvent((IEvent)memberDefinition, substitution);
+			} else {
+				throw new NotSupportedException("Unknown IMember: " + memberDefinition);
+			}
 		}
 		
-		internal static TypeVisitor GetSubstitution(IType declaringType)
+		public IMemberReference ToMemberReference()
 		{
-			ParameterizedType pt = declaringType as ParameterizedType;
+			return new SpecializingMemberReference(
-			if (pt != null)
+				memberDefinition.ToMemberReference(),
-				return pt.GetSubstitution();
+				ToTypeReference(substitution.ClassTypeArguments),
-			else
+				ToTypeReference(substitution.MethodTypeArguments));
-				return null;
 		}
 		
-		internal static IType Substitute(IType type, TypeVisitor substitution)
+		static IList<ITypeReference> ToTypeReference(IList<IType> typeArguments)
 		{
-			if (substitution == null)
+			if (typeArguments == null)
-				return type;
+				return null;
 			else
-				return type.AcceptVisitor(substitution);
+				return typeArguments.Select(t => t.ToTypeReference()).ToArray();
 		}
 		
-		internal IMethod WrapAccessor(IMethod accessorDefinition)
+		internal IMethod WrapAccessor(ref IMethod cachingField, IMethod accessorDefinition)
 		{
 			if (accessorDefinition == null)
 				return null;
+			var result = LazyInit.VolatileRead(ref cachingField);
+			if (result != null)
+				return result;
 			else
-				return new SpecializedMethod(declaringType, accessorDefinition);
+				return LazyInit.GetOrSet(ref cachingField, new SpecializedMethod(accessorDefinition, substitution));
+		}
+		
+		/// <summary>
+		/// Gets the substitution belonging to this specialized member.
+		/// </summary>
+		public TypeParameterSubstitution Substitution {
+			get { return substitution; }
 		}
 		
 		public IType DeclaringType {
-			get { return declaringType; }
+			get {
+				var result = LazyInit.VolatileRead(ref this.declaringType);
+				if (result != null)
+					return result;
+				IType definitionDeclaringType = memberDefinition.DeclaringType;
+				ITypeDefinition definitionDeclaringTypeDef = definitionDeclaringType as ITypeDefinition;
+				if (definitionDeclaringTypeDef != null && definitionDeclaringType.TypeParameterCount > 0) {
+					if (substitution.ClassTypeArguments != null && substitution.ClassTypeArguments.Count == definitionDeclaringType.TypeParameterCount) {
+						result = new ParameterizedType(definitionDeclaringTypeDef, substitution.ClassTypeArguments);
+					} else {
+						result = new ParameterizedType(definitionDeclaringTypeDef, definitionDeclaringTypeDef.TypeParameters).AcceptVisitor(substitution);
+					}
+				} else {
+					result = definitionDeclaringType.AcceptVisitor(substitution);
+				}
+				return LazyInit.GetOrSet(ref this.declaringType, result);
+			}
+			internal set {
+				// This setter is used as an optimization when the code constructing
+				// the SpecializedMember already knows the declaring type.
+				Debug.Assert(this.declaringType == null);
+				Debug.Assert(value != null);
+				// As this setter is used only during construction before the member is published
+				// to other threads, we don't need a volatile write.
+				this.declaringType = value;
+			}
 		}
 		
 		public IMember MemberDefinition {
@@ -94,8 +152,21 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 		}
 		
 		public IType ReturnType {
-			get { return returnType; }
+			get {
-			protected set { returnType = value; }
+				var result = LazyInit.VolatileRead(ref this.returnType);
+				if (result != null)
+					return result;
+				else
+					return LazyInit.GetOrSet(ref this.returnType, memberDefinition.ReturnType.AcceptVisitor(substitution));
+			}
+			protected set {
+				// This setter is used for LiftedUserDefinedOperator, a special case of specialized member
+				// (not a normal type parameter substitution).
+				
+				// As this setter is used only during construction before the member is published
+				// to other threads, we don't need a volatile write.
+				this.returnType = value;
+			}
 		}
 		
 		public bool IsVirtual {
@@ -143,19 +214,11 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			var definitionImplementations = memberDefinition.ImplementedInterfaceMembers;
 			IMember[] result = new IMember[definitionImplementations.Count];
 			for (int i = 0; i < result.Length; i++) {
-				result[i] = Specialize(definitionImplementations[i]);
+				result[i] = SpecializedMember.Create(definitionImplementations[i], substitution);
 			}
 			return result;
 		}
 		
-		/// <summary>
-		/// Specialize another member using the same type arguments as this member.
-		/// </summary>
-		protected virtual IMember Specialize(IMember otherMember)
-		{
-			return SpecializingMemberReference.CreateSpecializedMember(declaringType, memberDefinition, null);
-		}
-		
 		public bool IsExplicitInterfaceImplementation {
 			get { return memberDefinition.IsExplicitInterfaceImplementation; }
 		}
@@ -241,13 +304,13 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			SpecializedMember other = obj as SpecializedMember;
 			if (other == null)
 				return false;
-			return this.declaringType.Equals(other.declaringType) && this.memberDefinition.Equals(other.memberDefinition);
+			return this.memberDefinition.Equals(other.memberDefinition) && this.substitution.Equals(other.substitution);
 		}
 		
 		public override int GetHashCode()
 		{
 			unchecked {
-				return 1000000007 * declaringType.GetHashCode() + 1000000009 * memberDefinition.GetHashCode();
+				return 1000000007 * memberDefinition.GetHashCode() + 1000000009 * substitution.GetHashCode();
 			}
 		}
 		
@@ -256,11 +319,11 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			StringBuilder b = new StringBuilder("[");
 			b.Append(GetType().Name);
 			b.Append(' ');
-			b.Append(declaringType.ToString());
+			b.Append(this.DeclaringType.ToString());
 			b.Append('.');
 			b.Append(this.Name);
 			b.Append(':');
-			b.Append(returnType.ToString());
+			b.Append(this.ReturnType.ToString());
 			b.Append(']');
 			return b.ToString();
 		}
@@ -270,36 +333,48 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 	{
 		IList<IParameter> parameters;
 		
-		protected SpecializedParameterizedMember(IType declaringType, IParameterizedMember memberDefinition)
+		protected SpecializedParameterizedMember(IParameterizedMember memberDefinition)
-			: base(declaringType, memberDefinition)
+			: base(memberDefinition)
 		{
 		}
 		
-		protected override void Initialize(TypeVisitor substitution)
+		public IList<IParameter> Parameters {
-		{
+			get {
-			base.Initialize(substitution);
+				var result = LazyInit.VolatileRead(ref this.parameters);
+				if (result != null)
+					return result;
+				else
+					return LazyInit.GetOrSet(ref this.parameters, CreateParameters(this.Substitution));
+			}
+			protected set {
+				// This setter is used for LiftedUserDefinedOperator, a special case of specialized member
+				// (not a normal type parameter substitution).
+				
+				// As this setter is used only during construction before the member is published
+				// to other threads, we don't need a volatile write.
+				this.parameters = value;
+			}
+		}
 		
+		protected IList<IParameter> CreateParameters(TypeVisitor substitution)
+		{
 			var paramDefs = ((IParameterizedMember)this.MemberDefinition).Parameters;
 			if (paramDefs.Count == 0) {
-				this.parameters = EmptyList<IParameter>.Instance;
+				return EmptyList<IParameter>.Instance;
 			} else {
 				var parameters = new IParameter[paramDefs.Count];
 				for (int i = 0; i < parameters.Length; i++) {
-					IType newType = Substitute(paramDefs[i].Type, substitution);
+					IType newType = paramDefs[i].Type.AcceptVisitor(substitution);
 					if (newType != paramDefs[i].Type) {
 						parameters[i] = new SpecializedParameter(paramDefs[i], newType);
 					} else {
 						parameters[i] = paramDefs[i];
 					}
 				}
-				this.parameters = Array.AsReadOnly(parameters);
+				return Array.AsReadOnly(parameters);
 			}
 		}
 		
-		public IList<IParameter> Parameters {
-			get { return parameters; }
-		}
-		
 		public override string ToString()
 		{
 			StringBuilder b = new StringBuilder("[");
@@ -309,9 +384,9 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			b.Append('.');
 			b.Append(this.Name);
 			b.Append('(');
-			for (int i = 0; i < parameters.Count; i++) {
+			for (int i = 0; i < this.Parameters.Count; i++) {
 				if (i > 0) b.Append(", ");
-				b.Append(parameters[i].ToString());
+				b.Append(this.Parameters[i].ToString());
 			}
 			b.Append("):");
 			b.Append(this.ReturnType.ToString());
@@ -326,7 +401,10 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			
 			public SpecializedParameter(IParameter originalParameter, IType newType)
 			{
-				this.originalParameter = originalParameter;
+				if (originalParameter is SpecializedParameter)
+					this.originalParameter = ((SpecializedParameter)originalParameter).originalParameter;
+				else
+					this.originalParameter = originalParameter;
 				this.newType = newType;
 			}
 			

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/SpecializedMethod.cs

@@ -32,50 +32,36 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 	public class SpecializedMethod : SpecializedParameterizedMember, IMethod
 	{
 		readonly IMethod methodDefinition;
-		readonly IList<IType> typeArguments;
+		readonly ITypeParameter[] specializedTypeParameters;
-		readonly IList<ITypeParameter> specializedTypeParameters;
 		
-		public SpecializedMethod(IType declaringType, IMethod methodDefinition, IList<IType> typeArguments = null)
+		public SpecializedMethod(IMethod methodDefinition, TypeParameterSubstitution substitution)
-			: this(declaringType, methodDefinition, typeArguments, GetSubstitution(declaringType, typeArguments))
+			: base(methodDefinition)
 		{
-		}
+			// The base ctor might have unpacked a SpecializedMember
-		
+			// (in case we are specializing an already-specialized method)
-		internal protected SpecializedMethod(IType declaringType, IMethod methodDefinition, IList<IType> typeArguments, TypeVisitor substitution)
+			methodDefinition = (IMethod)base.MemberDefinition;
-			: base(declaringType, methodDefinition)
-		{
-			if (declaringType == null)
-				throw new ArgumentNullException("declaringType");
-			if (methodDefinition == null)
-				throw new ArgumentNullException("methodDefinition");
-			
 			this.methodDefinition = methodDefinition;
-			this.typeArguments = typeArguments ?? EmptyList<IType>.Instance;
-			
 			if (methodDefinition.TypeParameters.Any(ConstraintNeedsSpecialization)) {
 				// The method is generic, and we need to specialize the type parameters
 				specializedTypeParameters = new ITypeParameter[methodDefinition.TypeParameters.Count];
-				for (int i = 0; i < specializedTypeParameters.Count; i++) {
+				for (int i = 0; i < specializedTypeParameters.Length; i++) {
 					ITypeParameter tp = methodDefinition.TypeParameters[i];
 					if (ConstraintNeedsSpecialization(tp))
-						tp = new SpecializedTypeParameter(tp, this, substitution);
+						tp = new SpecializedTypeParameter(tp, this);
 					specializedTypeParameters[i] = tp;
 				}
+				// add substitution that replaces the base method's type parameters with our specialized version
+				AddSubstitution(new TypeParameterSubstitution(null, specializedTypeParameters));
 			}
-			if (typeArguments != null && typeArguments.Count > 0) {
+			// Add the main substitution after the method type parameter specialization.
-				if (typeArguments.Count != methodDefinition.TypeParameters.Count)
+			AddSubstitution(substitution);
-					throw new ArgumentException("Incorrect number of type arguments");
+			if (specializedTypeParameters != null) {
-			} else if (specializedTypeParameters != null) {
+				// Set the substitution on the type parameters to the final composed substitution
-				// No type arguments were specified, but the method is generic.
+				foreach (var tp in specializedTypeParameters.OfType<SpecializedTypeParameter>()) {
-				// -> substitute original type parameters with the specialized ones
+					if (tp.Owner == this)
-				substitution = GetSubstitution(declaringType, specializedTypeParameters.ToArray<IType>());
+						tp.substitution = base.Substitution;
-				for (int i = 0; i < specializedTypeParameters.Count; i++) {
-					if (ConstraintNeedsSpecialization(methodDefinition.TypeParameters[i])) {
-						((SpecializedTypeParameter)specializedTypeParameters[i]).substitution = substitution;
-					}
 				}
 			}
-			
-			Initialize(substitution);
 		}
 		
 		static bool ConstraintNeedsSpecialization(ITypeParameter tp)
@@ -95,53 +81,13 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 				return null;
 		}
 		
-		public override IMemberReference ToMemberReference()
-		{
-			return new SpecializingMemberReference(
-				this.DeclaringType.ToTypeReference(),
-				this.MemberDefinition.ToMemberReference(),
-				typeArguments.Select(ta => ta.ToTypeReference()).ToList()
-			);
-		}
-		
-		protected override IMember Specialize(IMember otherMember)
-		{
-			return SpecializingMemberReference.CreateSpecializedMember(this.DeclaringType, this.MemberDefinition, typeArguments);
-		}
-		
 		/// <summary>
 		/// Gets the type arguments passed to this method.
 		/// If only the type parameters for the class were specified and the generic method
 		/// itself is not specialized yet, this property will return an empty list.
 		/// </summary>
 		public IList<IType> TypeArguments {
-			get { return typeArguments; }
+			get { return this.Substitution.MethodTypeArguments ?? EmptyList<IType>.Instance; }
-		}
-		
-		public override int GetHashCode()
-		{
-			int hashCode = base.GetHashCode();
-			unchecked {
-				for (int i = 0; i < typeArguments.Count; i++) {
-					hashCode *= 362631391;
-					hashCode += typeArguments[i].GetHashCode();
-				}
-			}
-			return hashCode;
-		}
-		
-		public override bool Equals(object obj)
-		{
-			SpecializedMethod other = obj as SpecializedMethod;
-			if (!base.Equals(other))
-				return false;
-			if (typeArguments.Count != other.typeArguments.Count)
-				return false;
-			for (int i = 0; i < typeArguments.Count; i++) {
-				if (!typeArguments[i].Equals(other.typeArguments[i]))
-					return false;
-			}
-			return true;
 		}
 		
 		public IList<IUnresolvedMethod> Parts {
@@ -182,11 +128,11 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			b.Append(this.DeclaringType.ToString());
 			b.Append('.');
 			b.Append(this.Name);
-			if (typeArguments.Count > 0) {
+			if (this.TypeArguments.Count > 0) {
 				b.Append('[');
-				for (int i = 0; i < typeArguments.Count; i++) {
+				for (int i = 0; i < this.TypeArguments.Count; i++) {
 					if (i > 0) b.Append(", ");
-					b.Append(typeArguments[i].ToString());
+					b.Append(this.TypeArguments[i].ToString());
 				}
 				b.Append(']');
 			}
@@ -205,14 +151,15 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 		{
 			readonly ITypeParameter baseTp;
 			
-			// not readonly: The substition may be replaced at the end of SpecializedMethod constructor
+			// The substition is set at the end of SpecializedMethod constructor
 			internal TypeVisitor substitution;
 			
-			public SpecializedTypeParameter(ITypeParameter baseTp, IMethod specializedOwner, TypeVisitor substitution)
+			public SpecializedTypeParameter(ITypeParameter baseTp, IMethod specializedOwner)
 				: base(specializedOwner, baseTp.Index, baseTp.Name, baseTp.Variance, baseTp.Attributes, baseTp.Region)
 			{
+				// We don't have to consider already-specialized baseTps because
+				// we read the baseTp directly from the unpacked memberDefinition.
 				this.baseTp = baseTp;
-				this.substitution = substitution;
 			}
 			
 			public override int GetHashCode()

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/SpecializedProperty.cs

@@ -27,18 +27,11 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 	{
 		readonly IProperty propertyDefinition;
 		
-		public SpecializedProperty(IType declaringType, IProperty propertyDefinition)
+		public SpecializedProperty(IProperty propertyDefinition, TypeParameterSubstitution substitution)
-			: base(declaringType, propertyDefinition)
+			: base(propertyDefinition)
 		{
-			this.propertyDefinition = propertyDefinition;
+			AddSubstitution(substitution);
-			Initialize(GetSubstitution(declaringType));
+			this.propertyDefinition = (IProperty)base.MemberDefinition;
-		}
-		
-		internal SpecializedProperty(IType declaringType, IProperty propertyDefinition, TypeVisitor substitution)
-			: base(declaringType, propertyDefinition)
-		{
-			this.propertyDefinition = propertyDefinition;
-			Initialize(substitution);
 		}
 		
 		public bool CanGet {
@@ -49,12 +42,14 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			get { return propertyDefinition.CanSet; }
 		}
 		
+		IMethod getter, setter;
+		
 		public IMethod Getter {
-			get { return WrapAccessor(propertyDefinition.Getter); }
+			get { return WrapAccessor(ref this.getter, propertyDefinition.Getter); }
 		}
 		
 		public IMethod Setter {
-			get { return WrapAccessor(propertyDefinition.Setter); }
+			get { return WrapAccessor(ref this.setter, propertyDefinition.Setter); }
 		}
 		
 		public bool IsIndexer {

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/SpecializingMemberReference.cs

@@ -24,50 +24,29 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 	[Serializable]
 	public sealed class SpecializingMemberReference : IMemberReference
 	{
-		ITypeReference declaringTypeReference;
 		IMemberReference memberDefinitionReference;
-		IList<ITypeReference> typeArgumentReferences;
+		IList<ITypeReference> classTypeArgumentReferences;
+		IList<ITypeReference> methodTypeArgumentReferences;
 		
-		public SpecializingMemberReference(ITypeReference declaringTypeReference, IMemberReference memberDefinitionReference, IList<ITypeReference> typeArgumentReferences = null)
+		public SpecializingMemberReference(IMemberReference memberDefinitionReference, IList<ITypeReference> classTypeArgumentReferences = null, IList<ITypeReference> methodTypeArgumentReferences = null)
 		{
-			if (declaringTypeReference == null)
-				throw new ArgumentNullException("declaringTypeReference");
 			if (memberDefinitionReference == null)
 				throw new ArgumentNullException("memberDefinitionReference");
-			this.declaringTypeReference = declaringTypeReference;
 			this.memberDefinitionReference = memberDefinitionReference;
-			this.typeArgumentReferences = typeArgumentReferences;
+			this.classTypeArgumentReferences = classTypeArgumentReferences;
+			this.methodTypeArgumentReferences = methodTypeArgumentReferences;
 		}
 		
 		public IMember Resolve(ITypeResolveContext context)
 		{
-			var declaringType = declaringTypeReference.Resolve(context);
 			var memberDefinition = memberDefinitionReference.Resolve(context);
-			IType[] typeArguments = null;
+			return SpecializedMember.Create(
-			if (typeArgumentReferences != null) {
+				memberDefinition,
-				typeArguments = new IType[typeArgumentReferences.Count];
+				new TypeParameterSubstitution(
-				for (int i = 0; i < typeArguments.Length; i++) {
+					classTypeArgumentReferences != null ? classTypeArgumentReferences.Resolve(context) : null,
-					typeArguments[i] = typeArgumentReferences[i].Resolve(context);
+					methodTypeArgumentReferences != null ? methodTypeArgumentReferences.Resolve(context) : null
-				}
+				)
-			}
+			);
-			return CreateSpecializedMember(declaringType, memberDefinition, typeArguments);
-		}
-		
-		internal static IMember CreateSpecializedMember(IType declaringType, IMember memberDefinition, IList<IType> typeArguments)
-		{
-			if (memberDefinition == null) {
-				return null;
-			} else if (memberDefinition is IMethod) {
-				return new SpecializedMethod(declaringType, (IMethod)memberDefinition, typeArguments);
-			} else if (memberDefinition is IProperty) {
-				return new SpecializedProperty(declaringType, (IProperty)memberDefinition);
-			} else if (memberDefinition is IField) {
-				return new SpecializedField(declaringType, (IField)memberDefinition);
-			} else if (memberDefinition is IEvent) {
-				return new SpecializedEvent(declaringType, (IEvent)memberDefinition);
-			} else {
-				throw new NotSupportedException("Unknown IMember: " + memberDefinition);
-			}
 		}
 	}
 }

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/Implementation/TypeParameterSubstitution.cs

@@ -27,6 +27,11 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 	/// </summary>
 	public class TypeParameterSubstitution : TypeVisitor
 	{
+		/// <summary>
+		/// The identity function.
+		/// </summary>
+		public static readonly TypeParameterSubstitution Identity = new TypeParameterSubstitution(null, null);
+		
 		readonly IList<IType> classTypeArguments;
 		readonly IList<IType> methodTypeArguments;
 		
@@ -47,6 +52,95 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			this.methodTypeArguments = methodTypeArguments;
 		}
 		
+		/// <summary>
+		/// Gets the list of class type arguments.
+		/// Returns <c>null</c> if this substitution keeps class type parameter unmodified.
+		/// </summary>
+		public IList<IType> ClassTypeArguments {
+			get { return classTypeArguments; }
+		}
+		
+		public IList<IType> MethodTypeArguments {
+			get { return methodTypeArguments; }
+		}
+		
+		#region Compose
+		/// <summary>
+		/// Computes a single TypeParameterSubstitution so that for all types <c>t</c>:
+		/// <c>t.AcceptVisitor(Compose(g, f)) equals t.AcceptVisitor(f).AcceptVisitor(g)</c>
+		/// </summary>
+		/// <remarks>If you consider type parameter substitution to be a function, this is function composition.</remarks>
+		public static TypeParameterSubstitution Compose(TypeParameterSubstitution g, TypeParameterSubstitution f)
+		{
+			if (g == null)
+				return f;
+			if (f == null || (f.classTypeArguments == null && f.methodTypeArguments == null))
+				return g;
+			// The composition is a copy of 'f', with 'g' applied on the array elements.
+			// If 'f' has a null list (keeps type parameters unmodified), we have to treat it as
+			// the identity function, and thus use the list from 'g'.
+			var classTypeArguments = f.classTypeArguments != null ? GetComposedTypeArguments(f.classTypeArguments, g) : g.classTypeArguments;
+			var methodTypeArguments = f.methodTypeArguments != null ? GetComposedTypeArguments(f.methodTypeArguments, g) : g.methodTypeArguments;
+			return new TypeParameterSubstitution(classTypeArguments, methodTypeArguments);
+		}
+		
+		static IList<IType> GetComposedTypeArguments(IList<IType> input, TypeParameterSubstitution substitution)
+		{
+			IType[] result = new IType[input.Count];
+			for (int i = 0; i < result.Length; i++) {
+				result[i] = input[i].AcceptVisitor(substitution);
+			}
+			return result;
+		}
+		#endregion
+		
+		#region Equals and GetHashCode implementation
+		public override bool Equals(object obj)
+		{
+			TypeParameterSubstitution other = obj as TypeParameterSubstitution;
+			if (other == null)
+				return false;
+			return TypeListEquals(classTypeArguments, other.classTypeArguments)
+				&& TypeListEquals(methodTypeArguments, other.methodTypeArguments);
+		}
+		
+		public override int GetHashCode()
+		{
+			unchecked {
+				return 1124131 * TypeListHashCode(classTypeArguments) + 1821779 * TypeListHashCode(methodTypeArguments);
+			}
+		}
+		
+		static bool TypeListEquals(IList<IType> a, IList<IType> b)
+		{
+			if (a == b)
+				return true;
+			if (a == null || b == null)
+				return false;
+			if (a.Count != b.Count)
+				return false;
+			for (int i = 0; i < a.Count; i++) {
+				if (!a[i].Equals(b[i]))
+					return false;
+			}
+			return true;
+		}
+		
+		static int TypeListHashCode(IList<IType> obj)
+		{
+			if (obj == null)
+				return 0;
+			unchecked {
+				int hashCode = 1;
+				foreach (var element in obj) {
+					hashCode *= 27;
+					hashCode += element.GetHashCode();
+				}
+				return hashCode;
+			}
+		}
+		#endregion
+		
 		public override IType VisitTypeParameter(ITypeParameter type)
 		{
 			int index = type.Index;

src/Libraries/NRefactory/ICSharpCode.NRefactory/TypeSystem/InheritanceHelper.cs

@@ -19,6 +19,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using ICSharpCode.NRefactory.TypeSystem.Implementation;
 
 namespace ICSharpCode.NRefactory.TypeSystem
 {
@@ -50,13 +51,15 @@ namespace ICSharpCode.NRefactory.TypeSystem
 			if (member == null)
 				throw new ArgumentNullException("member");
 			
-			member = member.MemberDefinition;
 			if (member.IsExplicitInterfaceImplementation && member.ImplementedInterfaceMembers.Count == 1) {
 				// C#-style explicit interface implementation
-				yield return member.ImplementedInterfaceMembers[0];
+				member = member.ImplementedInterfaceMembers[0];
-				member = member.ImplementedInterfaceMembers[0].MemberDefinition;
+				yield return member;
 			}
 			
+			SpecializedMember specializedMember = member as SpecializedMember;
+			member = member.MemberDefinition;
+			
 			IEnumerable<IType> allBaseTypes;
 			if (includeImplementedInterfaces) {
 				allBaseTypes = member.DeclaringTypeDefinition.GetAllBaseTypes();
@@ -68,8 +71,12 @@ namespace ICSharpCode.NRefactory.TypeSystem
 					continue;
 				
 				foreach (IMember baseMember in baseType.GetMembers(m => m.Name == member.Name, GetMemberOptions.IgnoreInheritedMembers)) {
-					if (SignatureComparer.Ordinal.Equals(member, baseMember))
+					if (SignatureComparer.Ordinal.Equals(member, baseMember)) {
-						yield return baseMember;
+						if (specializedMember != null)
+							yield return SpecializedMember.Create(baseMember, specializedMember.Substitution);
+						else
+							yield return baseMember;
+					}
 				}
 			}
 		}