message: vec test: check number validity
diff: -// compile-flags: -Zmiri-tag-raw-pointers
  +// compile-flags: -Zmiri-tag-raw-pointers -Zmiri-check-number-validity
  // Gather all references from a mutable iterator and make sure Miri notices if
  // using them is dangerous.
  fn test_all_refs<'a, T: 'a>(dummy: &mut T, iter: impl Iterator<Item = &'a mut T>) {
  