Cannot cast the type into its generic parameter using operator (op_Implicit or op_Explicit) even if nothing runs wrong (using reflection)

[CaryCatZ]

It seems an operator declaration with a generic parameter of class would not work.
TestClass<string> as string does not work even if TestClass defines operator T(TestClass<T>).

An interface:

namespace TestProject1;

public interface IWrapper<TWrapper, TWrapped> where TWrapper : IWrapper<TWrapper, TWrapped>
{
  public TWrapped Wrapped { get; }

  public static virtual implicit operator TWrapped(TWrapper @this) => @this.Wrapped;
}

It represents a wrapper and it can be cast into TWrapped.

And two same wrappers:

namespace TestProject1;

public class Wrapper1<TWrapped> : IWrapper<Wrapper1<TWrapped>, TWrapped>
{
  public Wrapper1(TWrapped wrapped)
  {
    Wrapped = wrapped;
  }

  public TWrapped Wrapped { get; }
}

and

namespace TestProject1;

public class Wrapper2<TWrapped> : IWrapper<Wrapper2<TWrapped>, TWrapped>
{
  public Wrapper2(TWrapped wrapped)
  {
    Wrapped = wrapped;
  }

  public TWrapped Wrapped { get; }
}

and

namespace TestProject1;

public class GenericCast<T>
{
  public T val;

  public GenericCast(T val)
  {
    this.val = val;
  }

  public static implicit operator T(GenericCast<T> @this) => @this.val;
}

However, now, the cast from Wrapper1 to Wrapper2 does not work.

var wrapper1 = new Wrapper1<Wrapper2<int>>(new Wrapper2<int>(42));
// Console.WriteLine((wrapper1 as Wrapper2<int>).Wrapped); // does not work, even if `TWrapped` is `Wrapper2<int>`

var g = new GenericCast<string>("Value");
// Console.WriteLine(g as string); // does not work
// Console.WriteLine(GenericCast<string>.op_Implicit(g)); // CS0571
Console.WriteLine(typeof(GenericCast<string>).GetMethod("op_Implicit").Invoke(null, new object?[]{g})); // reflection works well

Even though operator TWrapped were moved to Wrapper1 and Wrapper2, it would not work, either.
Look at GenericCast<T>, although operator T is declared, the cast from GenericCast<string> to string does not work, either.

I think this is strange, is this a bug?

[saucecontrol]

From:
https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/type-testing-and-cast#as-operator

The as operator considers only reference, nullable, boxing, and unboxing conversions. You can't use the as operator to perform a user-defined conversion. To do that, use a cast expression.

[CaryCatZ]

Thanks a lot, problem solved.