roslyn: Variable from `using` cannot be used as `ref` or `out`

Version Used: 15.7 Preview 4

Steps to Reproduce:

using System;
public class C {
  public void M() {
    using (var d = new D())
    {
      d.Move();
      d.Move2(); // error CS1657: Cannot use 'd' as a ref or out value because it is a 'using variable'
    }
  }
}

public struct D : IDisposable
{
  public void Move() { }
  public void Dispose() { }
}

public static class DExtensions
{
  public static void Move2(ref this D d) { d.Move(); }
}

Expected Behavior:

The calls to Move() and Move2() are equivalent.

Actual Behavior:

The call to Move2() results in the error described.

Additional Information:

The call to Move() shows that invocations using a reference to a value used in a using statement are allowed in some contexts. In these contexts, CS1657 appears to be an arbitrary language limitation that could be removed. Allowing by-ref calls in this context would simplify the implementation of an allocation-free OwnedDisposable<T>, which I’m creating as part of an experimental way to address dotnet/roslyn-analyzers#1617. This limitation forces the code to use try/finally instead of the equivalent using statement.