VB .NET project Compiles failed when use the Extension Function wrote by C++/CLI

Question

I wrote a C++/CLI Assembly and use the [ExtensionAttribute],coding like this:

using namespace System::Runtime::CompilerServices;

namespace ExFunLibWithCli {
  public ref class ClassBase
  {
    public:
    int BaseFun()
    {
      return 32;
    }
  };

  [ExtensionAttribute]
  public ref class ClassBaseExtensions abstract sealed
  {
    public:
    [ExtensionAttribute]
    static int ExtensionFunc(ClassBase^ cb)
    {
      return 64;
    }
  };
}

In another C# .NET project,I add the Assembly generated by this code to be referenced and coding like:

static void Main(string[] args)
{

  var cb = new ClassBase();

  int res = cb.ExtensionFunc();

}

It compiles and works well!

Now I create another VB .NET project,and do the same thing:

Sub Main()
  Dim cb = New ClassBase
  Dim res = cb.ExtensionFunc()                     'this line compiles failed
  Dim res = ClassBaseExtensions.ExtensionFunc(cb)  'this line can compiles and work well,but I want to use ClassBase directly
End Sub

btw,When I use C# to write the class and functions decorated by [ExtensionAttribute],and use it in the same VB.NET project,it also compiles and work well.

So i'm really confused about it.

Answer 1

Try adding this line to your C++/CLI code (or to AssemblyInfo.cpp, which is usually present):

[assembly:Extension];

Then rebuild the projects.