[wasm] generic constraint failure

[lewing]

using System;
using System.Runtime.InteropServices;

public class HelloWorld
{
	public static void Main (String[] args) {
		Type t = typeof(WeakReference<>).MakeGenericType(typeof(int));
		object o = Activator.CreateInstance(t, 42);
		Console.WriteLine(o.GetType());	
	}
}

Fails with the following when run as wasm:

Arguments: --run,hello.exe
Loaded: hello.exe
Loaded: mscorlib.dll
initializing mono runtime
>>mono_wasm_runtime_ready
WASM: Initializing.....
Exception:System.MissingMethodException: Constructor on type 'System.WeakReference`1[[System.Int32, mscorlib, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]]' not found.
  at System.RuntimeType.CreateInstanceImpl (System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder binder, System.Object[] args, System.Globalization.CultureInfo culture, System.Object[] activationAttributes, System.Threading.StackCrawlMark& stackMark) <0x172cd58 + 0x00326> in <6ba6c39bf14343a8affd38a7b99e0332>:0 
  at System.Activator.CreateInstance (System.Type type, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder binder, System.Object[] args, System.Globalization.CultureInfo culture, System.Object[] activationAttributes) <0x1723e10 + 0x000c8> in <6ba6c39bf14343a8affd38a7b99e0332>:0 
  at System.Activator.CreateInstance (System.Type type, System.Object[] args) <0x1723c58 + 0x00014> in <6ba6c39bf14343a8affd38a7b99e0332>:0 
  at HelloWorld.Main (System.String[] args) <0x171a328 + 0x0003e> in <8134cf97c5734b228594d7a0355a93a3>:0 
WASM-ERR: exit(1) called, but EXIT_RUNTIME is not set, so halting execution but not exiting the runtime or preventing further async execution (build with EXIT_RUNTIME=1, if you want a true shutdown)
make: *** [run-interp-sample] Error 1

But the MakeGenericType method should have failed like it does on desktop

Unhandled Exception:
System.ArgumentException: Invalid generic arguments
Parameter name: typeArguments
  at (wrapper managed-to-native) System.RuntimeType.MakeGenericType(System.Type,System.Type[])
  at System.RuntimeType.MakeGenericType (System.Type[] instantiation) [0x000e2] in <63a185bccd644d7ea7199ca475c500f2>:0 
  at HelloWorld.Main (System.String[] args) [0x00001] in <6c440b8a93b94072ad73a1e5862bc4e8>:0 
[ERROR] FATAL UNHANDLED EXCEPTION: System.ArgumentException: Invalid generic arguments
Parameter name: typeArguments
  at (wrapper managed-to-native) System.RuntimeType.MakeGenericType(System.Type,System.Type[])
  at System.RuntimeType.MakeGenericType (System.Type[] instantiation) [0x000e2] in <63a185bccd644d7ea7199ca475c500f2>:0 
  at HelloWorld.Main (System.String[] args) [0x00001] in <6c440b8a93b94072ad73a1e5862bc4e8>:0

[lewing]

@GrabYourPitchforks Thanks for the report we'll look into it

/cc @marek-safar