Fixed bug in simplify anonymous method issue.

ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/SimplifyAnonymousMethodToDelegateIssue.cs

@@ -27,6 +27,8 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using ICSharpCode.NRefactory.PatternMatching;
+using ICSharpCode.NRefactory.CSharp.Resolver;
+using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -96,6 +98,22 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 					i++;
 				}
 				AddIssue(expression, ctx.TranslateString("Expression can be reduced to delegate"), script =>  {
+					var validTypes = CreateFieldAction.GetValidTypes (ctx.Resolver, expression).ToList ();
+					if (validTypes.Any (t => t.FullName == "System.Func" && t.TypeParameterCount == 1 + parameters.Count) && validTypes.Any (t => t.FullName == "System.Action")) {
+						var rr = ctx.Resolve (invocation) as CSharpInvocationResolveResult;
+						if (rr != null && rr.Member.ReturnType.Kind != ICSharpCode.NRefactory.TypeSystem.TypeKind.Void) {
+							var builder = ctx.CreateTypeSytemAstBuilder (expression);
+							var type = builder.ConvertType(new TopLevelTypeName("System", "Func", 1));
+							var args = type is SimpleType ? ((SimpleType)type).TypeArguments : ((MemberType)type).TypeArguments;
+							args.Clear ();
+							foreach (var pde in parameters) {
+								args.Add (builder.ConvertType (ctx.Resolve (pde).Type));
+							}
+							args.Add (builder.ConvertType (rr.Member.ReturnType));
+							script.Replace(expression, new CastExpression (type, invocation.Target.Clone()));
+							return;
+						}
+					}
 					script.Replace(expression, invocation.Target.Clone());
 				});
 			}

ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/SimplifyAnonymousMethodToDelegateIssueTests.cs

@@ -160,6 +160,43 @@ class Foo
 			var issues = GetIssues (new SimplifyAnonymousMethodToDelegateIssue (), input, out context);
 			Assert.AreEqual (0, issues.Count);
 		}
+
+		/// <summary>
+		/// Bug 12184 - Expression can be reduced to delegate fix can create ambiguity
+		/// </summary>
+		[Test]
+		public void TestBug12184 ()
+		{
+			var input = @"using System;
+using System.Threading.Tasks;
+
+class C
+{
+	public C GetResponse () { return null; }
+
+	public static void Foo ()
+	{
+		Task.Factory.StartNew (() => GetResponse());
+	}
+}";
+
+			TestRefactoringContext context;
+			var issues = GetIssues (new SimplifyAnonymousMethodToDelegateIssue (), input, out context);
+			Assert.AreEqual (1, issues.Count);
+			CheckFix (context, issues, @"using System;
+using System.Threading.Tasks;
+
+class C
+{
+	public C GetResponse () { return null; }
+
+	public static void Foo ()
+	{
+		Task.Factory.StartNew ((Func<C>)GetResponse);
+	}
+}");
+
+		}
 	}
 }