gistfile1.txt

.assembly Test { }

.class public TestClass
	extends [mscorlib]System.Object
{
	.method specialname static public void Main() cil managed 
	{
		.entrypoint
		newobj instance void AnotherClass2::.ctor()
		dup
		callvirt instance void AnotherClass::Method(class AnotherClass)	
		ret
 	}

}

.class public AnotherClass
	extends [mscorlib]System.Object
{

	.method specialname rtspecialname public instance void .ctor() cil managed 
	{
		ldarg.0
		call instance void [mscorlib]System.Object::.ctor()
		ret
	}

	.method public void Method(class AnotherClass a) cil managed
	{
		ldarg.1
		call instance string AnotherClass::Something()
		call void [mscorlib]System.Console::WriteLine(string)
		ret
	}
	
	.method public instance string Something() cil managed
	{
		ldstr "AnotherClass"
		ret
	}

}

.class public AnotherClass2
	extends [mscorlib]System.Object
{
	.method specialname rtspecialname public instance void .ctor() cil managed 
	{
		ldarg.0
		call instance void [mscorlib]System.Object::.ctor()
		ret
	}

		
}

It's written by hand. Kinda stumbled over the fact that the runtime doesn't actually seem to enforce the type correctness of arguments being passed to methods, and just eventually got here.

Yes, in most languages most of the type checking usually occurs in previous steps of compilation before generating the IL code, so for efficiency reasons of compilation, it's not redone. .NET would be the same.