Implementing __typename for types that share a vertex variant is fiddly

[u9g]

Any way we can improve the experience on that with the trustfall derive macro?

[obi1kenobi]

Perhaps something like:

#[derive(TrustfallEnumVertex)]
pub enum Vertex {
    Span(...),
    Function(...),
    #[covers(JsxAttribute, HrefAttribute, RelAttribute)]
    JsxAttribute(Attribute),
}

where the Attribute value contained in that variant implements a new trait that manually implements typename?

Then the TrustfallEnumVertex-generated typename implementation could be something along the lines of:

match vertex {
    Vertex::Span(..) => "Span",
    Vertex::Function(..) => "Function",
    Vertex::JsxAttribute(attr) => <attr as NewTypenameTrait>.manual_typename(),
}

All names need some bikeshedding, of course. Aiming to show general idea, not commit to names.