{"ast_node_type":"variable","tokens":[{"end":68,"kind":"keyword","start":0,"text":"let"}]}
                let ty = fields[FieldIdx::ONE].ty(self.tcx(), args);
                let fields = &adt.non_enum_variant().fields;
                // FIXME: Are we just trying to map to the `T` in `MaybeUninit<T>`?