Bug 10551 - possible params bug
Summary: possible params bug
Status: RESOLVED FIXED
Alias: None
Product: Class Libraries
Classification: Mono
Component: mscorlib ()
Version: unspecified
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Marek Safar
URL:
Depends on:
Blocks:
 
Reported: 2013-02-21 15:26 UTC by Ronald Crooy
Modified: 2013-02-25 08:12 UTC (History)
4 users (show)

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

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Status:
RESOLVED FIXED

Description Ronald Crooy 2013-02-21 15:26:43 UTC
I found a bug, which does not occur on windows but does on my mac with mono (latest stable). I was able to narrow it down to this small example. The code was taken from the ServiceStack.Text project, in the file ReflectionExtensions.cs. I stripped out the ifdef stuff that is not relevant to my mac.

I didn't know if this is just a bug in the program or a mono bug, but I thought it best to file it in both projects. So the bug is also viewable on https://github.com/ServiceStack/ServiceStack.Text/issues/281

The exception this will generate is:
> System.InvalidProgramException: Invalid IL code in (wrapper dynamic-method) object:MyCtor (): IL_0001: newobj    0x00000001
> 
> 
>   at (wrapper managed-to-native) System.Delegate:CreateDelegate_internal (System.Type,object,System.Reflection.MethodInfo,bool)
>   at System.Delegate.CreateDelegate (System.Type type, System.Object firstArgument, System.Reflection.MethodInfo method, Boolean throwOnBindFailure, Boolean allowClosed) [0x0032c] in /Users/builder/data/lanes/mono-mac-ui-refresh-2-10/2baeee2f/source/bockbuild/profiles/mono-2-10/build-root/mono-2.10.11/_build/mono-2.10.11.git/mcs/class/corlib/System/Delegate.cs:265
>   at System.Delegate.CreateDelegate (System.Type type, System.Reflection.MethodInfo method, Boolean throwOnBindFailure) [0x00000] in /Users/builder/data/lanes/mono-mac-ui-refresh-2-10/2baeee2f/source/bockbuild/profiles/mono-2-10/build-root/mono-2.10.11/_build/mono-2.10.11.git/mcs/class/corlib/System/Delegate.cs:278
>   at System.Delegate.CreateDelegate (System.Type type, System.Reflection.MethodInfo method) [0x00000] in /Users/builder/data/lanes/mono-mac-ui-refresh-2-10/2baeee2f/source/bockbuild/profiles/mono-2-10/build-root/mono-2.10.11/_build/mono-2.10.11.git/mcs/class/corlib/System/Delegate.cs:283
>   at System.Reflection.Emit.DynamicMethod.CreateDelegate (System.Type delegateType) [0x0002f] in /Users/builder/data/lanes/mono-mac-ui-refresh-2-10/2baeee2f/source/bockbuild/profiles/mono-2-10/build-root/mono-2.10.11/_build/mono-2.10.11.git/mcs/class/corlib/System.Reflection.Emit/DynamicMethod.cs:168
>   at MonoBug.MonoBug.GetConstructorMethodToCache (System.Type type) [0x00062] in /Users/ronald/Development/MonoBug/MonoBug/Main.cs:36
>   at MonoBug.MonoBug.Main (System.String[] args) [0x00000] in /Users/ronald/Development/MonoBug/MonoBug/Main.cs:9
> 

```C#
using System;

namespace MonoBug
{
	public class MonoBug
	{
		public static void Main (string[] args)
		{
			//no problem
			GetConstructorMethodToCache (typeof(GoodThings));

			//problem 
			GetConstructorMethodToCache (typeof(BadThings));
		}

		public class GoodThings{
			public GoodThings ( string[] args)
			{
				
			}
		}

		public class BadThings
		{
			public BadThings (params string[] args)
			{
				
			}
		}

		public delegate object EmptyCtorDelegate();
			
		public static EmptyCtorDelegate GetConstructorMethodToCache(Type type)
		{
			var emptyCtor = type.GetConstructor(Type.EmptyTypes);
			if (emptyCtor != null)
			{
				

				var dm = new System.Reflection.Emit.DynamicMethod("MyCtor", type, Type.EmptyTypes, typeof(MonoBug).Module, true);

				var ilgen = dm.GetILGenerator();
				ilgen.Emit(System.Reflection.Emit.OpCodes.Nop);
				ilgen.Emit(System.Reflection.Emit.OpCodes.Newobj, emptyCtor);
				ilgen.Emit(System.Reflection.Emit.OpCodes.Ret);
				
				return (EmptyCtorDelegate)dm.CreateDelegate(typeof(EmptyCtorDelegate));

			}
			
			//Anonymous types don't have empty constructors
			//return () => FormatterServices.GetUninitializedObject(type);
			return null;
		}
	}
}


```
Comment 1 Zoltan Varga 2013-02-23 17:19:56 UTC
This is a problem in GetConstructor (), GetConstructor(Type.EmptyTypes) seems to match the params ctor on mono, but not on MS.NET.

Testcase:
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
using System;

public class MonoBug
{
	public static void Main (string[] args) {
		Console.WriteLine ("D: " + typeof (BadThings).GetConstructor (Type.EmptyTypes));
	}

	public class BadThings {
		public BadThings (params string[] args) {
		}
	}
}
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Comment 2 Marek Safar 2013-02-25 08:12:08 UTC
Fixed in master