Derive Macro ConditionallySelectable 

#[derive(ConditionallySelectable)]
{
    // Attributes available to this derive:
    #[sanitization]
}

Derive sanitization::ct::ConditionallySelectable for structs.

The generated implementation selects every field through that field’s own ConditionallySelectable implementation. #[sanitization(skip)] is intentionally rejected for this derive because the output must be a complete selection between left and right.

Enums and unions are rejected. Field-wise struct selection avoids raw representation reads and does not inspect padding bytes.