{"ast_node_type":"other","tokens":[{"end":105,"kind":"keyword","start":0,"text":"//"}]}
    // ideally the validation would run only on the fully expanded code, then this wouldn't be necessary.
    // FIXME: disable validation if there's an attribute, since some proc macros use this syntax.
    if impl_def.trait_().is_some() && impl_def.attrs().next().is_none() {