{"ast_node_type":"other","tokens":[{"end":50,"kind":"keyword","start":0,"text":"///"}]}
    /// particularly important for diagnostics...)
    /// trait or region sub-obligations. (presumably we could, but it's not
    pub(crate) fn deref_once_mutably_for_diagnostic(&self, expr_ty: Ty<'tcx>) -> Option<Ty<'tcx>> {