Consider the following minimal example:
Module Module1
Private Enum MyEnum
A
End Enum
Public Sub Main(args As String())
AreEqual(CType(0, MyEnum), MyEnum.A) ' Error here
End Sub
Private Function AreEqual(Of T)(item1 As T, item2 As T) As Boolean
Return False
End Function
Private Function AreEqual(item1 As Object, item2 As Object) As Boolean
Return False
End Function
End Module
For some strange reason, overload resolution fails in the line marked with "Error here":
Error 6 Overload resolution failed because no accessible 'AreEqual' is most specific for these arguments:
Private Function AreEqual(item1 As Object, item2 As Object) As Boolean: Not most specific.
Private Function AreEqual(Of MyEnum)(item1 As MyEnum, item2 As MyEnum) As Boolean: Not most specific.
Why is the second function not "most specific"? Both CType(0, MyEnum) and MyEnum.A should be expressions that are statically typed as MyEnum.
Interestingly, I can only reproduce this problem with casting an Enum. AreEqual(CType(0, Int32), 0) and AreEqual(MyEnum.A, MyEnum.A) both compile without problems.
I know how to fix this. I know that I can just use AreEqual(Of MyEnum)(...). That is not the question. I'm curious why this happens. Some compiler bug? Interestingly, the corresponding C# code does work:
enum MyEnum { A, B }
static void Main(string[] args)
{
AreEqual((MyEnum)0, MyEnum.A);
}
static bool AreEqual<T>(T item1, T item2) { return false; }
static bool AreEqual(object item1, object item2) { return false; }
