error[E0658]: the `linkage` attribute is experimental and not portable across platforms --> $DIR/linkage4.rs:1:1 | LL | #[linkage = "external"] | ^^^^^^^^^^^^^^^^^^^^^^^ | = note: see issue #29603 for more information = help: add `#![feature(linkage)]` to the crate attributes to enable error: aborting due to previous error For more information about this error, try `rustc --explain E0658`.