{"ast_node_type":"other","tokens":[{"end":20,"kind":"keyword","start":0,"text":"visitor:"}]}
    visitor: &mut V,
pub fn walk_field_def<'v, V: Visitor<'v>>(
    FieldDef { hir_id, ident, ty, default, span: _, vis_span: _, def_id: _, safety: _ }: &'v FieldDef<'v>,