Bug 39700 - Different behavior for RuntimeType.GetGenericTypeDefinition() between Mono and Windows
Summary: Different behavior for RuntimeType.GetGenericTypeDefinition() between Mono an...
Status: RESOLVED INVALID
Alias: None
Product: Runtime
Classification: Mono
Component: Reflection ()
Version: 4.2.0 (C6)
Hardware: PC Linux
: --- normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2016-03-16 22:19 UTC by Jeremy Meng
Modified: 2016-03-22 18:17 UTC (History)
2 users (show)

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

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.


Please create a new report on GitHub or Developer Community with your current version information, steps to reproduce, and relevant error messages or log files if you are hitting an issue that looks similar to this resolved bug and you do not yet see a matching new report.

Related Links:
Status:
RESOLVED INVALID

Description Jeremy Meng 2016-03-16 22:19:36 UTC
1. Compile and run the following Program.cs, targeting .NET Framework 4.5


using System;
using System.Collections.Generic;
using System.Reflection;
using System.Linq;

namespace ConsoleApplication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var method = typeof(MyOwnClass).GetMethod("Foo");
            var parameter = method.GetParameters()[0].ParameterType.GetElementType();
            var genericTypeDefinition = parameter.GetGenericTypeDefinition();
            Console.WriteLine(genericTypeDefinition.GetType().ToString());
        }
    }

    public abstract class MyOwnClass
    {
        public virtual void Foo<T>(List<T>[] action)
        {
        }

        /* ... */
    }
}

===========================================================================================================

Mono output:

System.MonoType

Windows output:

System.RuntimeType
Comment 1 Zoltan Varga 2016-03-19 11:26:54 UTC
This is not a bug, mono uses a differently named c# type internally to represent type objects. This is an implementation detail.
Comment 2 Jeremy Meng 2016-03-19 17:08:59 UTC
However it caused problem as these two types behaves differently. For example, calling GetTypeInfo() off a Mono type throws as it is not an IReflectableType.

Mono has System.RuntimeType too, just not in this specific code (where T is the open type parameter in an array of a generic type?)
Comment 3 Jeremy Meng 2016-03-19 17:12:10 UTC
This has caused some Castle.Core unit tests to fail only on Mono runtime.
Comment 4 Jeremy Meng 2016-03-22 18:17:36 UTC
It looks like the Castle.Core test failures are caused by a different reason.  See discussion at https://github.com/castleproject/Core/issues/160#issuecomment-199788363.