Can I narrow required properties from a descendant?

[doomchild]

Here's the sort of thing I'd like to be able to write:

public record Base
{
  public required string BaseThing { get; init; }
}

public record Derived
{
  public required string DerivedThing { get; init; }

  public Derived()
  {
    BaseThing = "abc";
  }
}

Derived d = new()
{
  DerivedThing = "def"
}

But I can't do that, because the instantiation of Derived still wants BaseThing set in the object initializer. I know I can use [SetsRequiredMembers] on the constructors, but then I lose the compiler warning if DerivedThing isn't set in the object initializer. Is there a way to effectively narrow the list of required fields in descendant types? I vastly prefer using object initializers, so I was really looking forward to being able to use the required keyword, but when we updated to 8 (we only use LTS releases, so I didn't try this on 7), I ran into this problem.

[TahirAhmadov]

The official response from the LDT is to 1) decorate the ctor with [SetsRequiredMembers], then 2) write your own analyzer which warns per your requirements.
People asked for [SetsMember(nameof(BaseThing))] kind of attribute but they rejected that idea for the language itself.

[doomchild]

Argh. I really like having the strictness of a compiler error, but I want to be able to specify base properties in descendant types (for things like defining more specific versions of general things). We do this now with records using primary constructors (where I can specify values for base properties), but I vastly prefer object initializers to constructor calls wherever possible.

It sounds like I'm just SOL on this. How disappointing.

[TahirAhmadov]

You can promote your analyzer warnings to errors with a project or a Directory.Build.props file setting.