error[E0658]: the `linkage` attribute is experimental and not portable across platforms --> $DIR/feature-gate-linkage.rs:2:5 | LL | #[linkage = "extern_weak"] static foo: *mut isize; | ^^^^^^^^^^^^^^^^^^^^^^^^^^ | = note: see issue #29603 for more information = help: add `#![feature(linkage)]` to the crate attributes to enable = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0658`.