Handled extension methods in type guessing code.

ICSharpCode.NRefactory.CSharp/Refactoring/CodeActions/CreateFieldAction.cs

@@ -113,13 +113,20 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			if (index < 0)
 				yield break;
 					
-			var targetResult = resolver.Resolve(invoke.Target);
-			if (targetResult is MethodGroupResolveResult) {
-				foreach (var method in ((MethodGroupResolveResult)targetResult).Methods) {
+			var targetResult = resolver.Resolve(invoke.Target) as MethodGroupResolveResult;
+			if (targetResult != null) {
+				foreach (var method in targetResult.Methods) {
 					if (index < method.Parameters.Count) {
 						yield return method.Parameters [index].Type;
 					}
 				}
+				foreach (var extMethods in targetResult.GetExtensionMethods ()) {
+					foreach (var extMethod in extMethods) {
+						if (index + 1 < extMethod.Parameters.Count) {
+							yield return extMethod.Parameters [index + 1].Type;
+						}
+					}
+				}
 			}
 		}
 

ICSharpCode.NRefactory.Tests/CSharp/CodeActions/CreateLocalVariableTests.cs

@@ -236,5 +236,48 @@ namespace ICSharpCode.NRefactory.CSharp.CodeActions
 }");
 		}
 
+		[Test]
+		public void TestExtensionMethod()
+		{
+			Test<CreateLocalVariableAction>(@"static class Ext { public static void Foo(this object o, string str) {} }
+class Test
+{
+	public static void Main (string[] args)
+	{
+		args.Foo($foo);
+	}
+}", @"static class Ext { public static void Foo(this object o, string str) {} }
+class Test
+{
+	public static void Main (string[] args)
+	{
+		string foo;
+		args.Foo(foo);
+	}
+}");
+		}
+
+
+		[Test]
+		public void TestExtensionMethodStaticInvocation()
+		{
+			Test<CreateLocalVariableAction>(@"static class Ext { public static void Foo(this object o, string str) {} }
+class Test
+{
+	public static void Main (string[] args)
+	{
+		Ext.Foo(args, $foo);
+	}
+}", @"static class Ext { public static void Foo(this object o, string str) {} }
+class Test
+{
+	public static void Main (string[] args)
+	{
+		string foo;
+		Ext.Foo(args, foo);
+	}
+}");
+		}
+
 	}
 }