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 <https://github.com/rust-lang/rust/issues/100758> for more information
   = help: add `#![feature(collapse_debuginfo)]` to the crate attributes to enable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0658`.