error[E0658]: the `#[needs_allocator]` attribute is an experimental feature --> $DIR/feature-gate-needs-allocator.rs:1:1 | LL | #![needs_allocator] | ^^^^^^^^^^^^^^^^^^^ | = help: add `#![feature(allocator_internals)]` to the crate attributes to enable error: aborting due to previous error For more information about this error, try `rustc --explain E0658`.