Compiler Error CS0729
Type 'type' is defined in this assembly, but a type forwarder is specified for it
You cannot use a type forwarder for a type defined in the same assembly.
Example
The following sample generates CS0729.
// CS0729.cs
// compile with: /target:library
using System.Runtime.CompilerServices;
[assembly:TypeForwardedTo(typeof(TestClass))] // CS0729
class TestClass {}