error[E0658]: the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate which contains the profiler runtime and will never be stable
  --> $DIR/feature-gate-profiler-runtime.rs:1:1
   |
LL | #![profiler_runtime]
   | ^^^^^^^^^^^^^^^^^^^^
   |
   = help: add `#![feature(profiler_runtime)]` 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   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date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`.