fn add_assist(
acc: &mut Assists,
ctx: &AssistContext<'_, '_>,
attr: &Attr,
old_derives: &[Path],
old_tree: &TokenTree,
old_trait_path: &Path,
replace_trait_mod_path: Option<ModPath>,
trait_: Option<Trait>,
adt: &Adt,
current_edition: Edition,
) -> Option<()>