message: also make sure the hook actually gets called
diff: #![feature(option_expect_none, option_unwrap_none)]
  -
  //! Test that panic locations for `#[track_caller]` functions in std have the correct
  //! location reported.
  +use std::sync::atomic::{AtomicUsize, Ordering};
  +
  +static HOOK_COUNT: AtomicUsize = AtomicUsize::new(0);
  +
  fn main() {
  // inspect the `PanicInfo` we receive to ensure the right file is the source
  std::panic::set_hook(Box::new(|info| {
  + HOOK_COUNT.fetch_add(1, Ordering::Relaxed);
  let actual = info.location().unwrap();
  if actual.file() != file!() {
  eprintln!("expected a location in the test file, found {:?}", actual);
  @@ -35,4 +39,6 @@ fn main() {
  // Cleanup: reset to default hook.
  drop(std::panic::take_hook());
  +
  + assert_eq!(HOOK_COUNT.load(Ordering::Relaxed), 8);
  }
  