/// A wrapper around reference that compares and hashes like a pointer.
/// Can be used as a key in sets/maps indexed by pointers to avoid `unsafe`.
#[derive(Debug)]
-pub struct PtrKey<'a, T: 'a>(pub &'a T);
+pub struct PtrKey<'a, T>(pub &'a T);
impl<'a, T> Clone for PtrKey<'a, T> {
fn clone(&self) -> Self { *self }