error[E0658]: the `#[collapse_debuginfo]` attribute is an experimental feature --> $DIR/feature-gate-collapse_debuginfo.rs:1:1 | LL | #[collapse_debuginfo] | ^^^^^^^^^^^^^^^^^^^^^ | = note: see issue #100758 for more information = help: add `#![feature(collapse_debuginfo)]` to the crate attributes to enable = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0658`.