Bug 634 - cannot compile using IEnumerable<my interface>
Summary: cannot compile using IEnumerable<my interface>
Alias: None
Product: iOS
Classification: Xamarin
Component: General ()
Version: 4.x
Hardware: Macintosh Mac OS
: --- major
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2011-09-05 01:52 UTC by Tohru Ohta
Modified: 2011-09-21 08:32 UTC (History)
3 users (show)

Is this bug a regression?: ---
Last known good build:

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Description Tohru Ohta 2011-09-05 01:52:20 UTC
I tried to compile following sample code, but compiler error.
I'm using Mono 2.10.5.

using System;
using System.Collections.Generic;

namespace Test
	public class TestClass : ITestClass
		public TestClass ()
	public interface ITestClass
	public static class TestClass2
		public static void Test()
			List<TestClass> list = new List<TestClass>();
			list.Add(new TestClass());
		public static void TestInterface(IEnumerable<ITestClass> arg) 

Error CS1502: The best overloaded method match for `Test.TestClass2.TestInterface(System.Collections.Generic.IEnumerable<Test.ITestClass>)' has some invalid arguments (CS1502) (test)
Error CS1503: Argument `#1' cannot convert `System.Collections.Generic.List<Test.TestClass>' expression to type `System.Collections.Generic.IEnumerable<Test.ITestClass>' (CS1503) (test)
Comment 1 Marek Safar 2011-09-05 04:49:08 UTC
You need to use dmcs compiler (.NET 4.0 profile) which supports interface covariance
Comment 2 Tohru Ohta 2011-09-06 05:02:14 UTC
Thank you.

I'm using MonoDevelop 2.6RC2 and could compile properly by changing Runtime verion to MONO / .Net4.0 in case C# Library Project.

There is option in Project Options -> Build -> General -> Runtime version.

But When I choose MonoTouch Library Project, I can't change this option and always disabled.
I need to compile by MonoTouch Library.
Could you tell me how I use dmcs compiler in this case?
Comment 3 Rolf Bjarne Kvinge [MSFT] 2011-09-21 08:32:04 UTC
Unfortunately you can't choose the compiler for MonoTouch.

It will be updated in a future release, but this is still somewhat far ahead (in particular it will not be in the next 5.0 release).