{"ast_node_type":"other","tokens":[{"end":89,"kind":"keyword","start":0,"text":"///"}]}
    /// span) for an *existing* error. Therefore, it is best-effort, and may never handle
    /// This is only used by error-reporting code to get a better cause (in particular, a better
    /// all of the cases that the normal `ty::Ty`-based wfcheck does. This is fine,