ref parameters on Primary constructors

[FaustVX]

Hi,

I just tried a few thing with primary constructors.
And I found a little bug in the compiler (I think).

You can't assign a ref parameter to a ref field/property in a primary ctor,

readonly ref struct C1(ref object ptr)
{
    public readonly ref object _ptr = ref ptr; // CS9077: Cannot return a parameter by reference 'ptr' through a ref parameter; it can only be returned in a return statement
}

But it works well in other scenario:

• ref of other field in Primary ctor

  readonly ref struct C1(ref object ptr)
  {
      public static object obj = new();
      public readonly ref object _ptrObj = ref obj; // Ok
  }

• ref of in parameter in Primary ctor (using Unsafe.AsRef())

  readonly ref struct C2(in object ptr)
  {
      public readonly ref object _ptr = ref Unsafe.AsRef(in ptr); // Ok
  }

But I found a workaround, using Unsafe.AsRef() of a ref parameter

readonly ref struct C3(ref object ptr)
{
    public readonly ref object _ptr = ref Unsafe.AsRef(in ptr); // Workaround
}

sharplab.io

[333fred]

Please file a bug on roslyn. @AlekseyTs fyi.

[FaustVX]

Ok, opened dotnet/roslyn#69055