{"ast_node_type":"other","tokens":[{"end":81,"kind":"keyword","start":0,"text":"#[diagnostic::on_unimplemented(message"}]}
#[diagnostic::on_unimplemented(message = "`{Self}` doesn't implement `DynSend`. \
            Add it to `rustc_data_structures::marker` or use `IntoDynSyncSend` if it's already `Send`")]