error: lifetime may not live long enough
  --> $DIR/hr-subtype.rs:54:13
   |
LL |           fn supertype<'x, 'y: 'x, 'z: 'y>() {
   |                        --  -- lifetime `'y` defined here
   |                        |
   |                        lifetime `'x` defined here
LL |               gimme::<$t1>(None::<$t2>);
   |               ^^^^^^^^^^^^^^^^^^^^^^^^^ argument requires that `'x` must outlive `'y`
...
LL | / check! { free_x_vs_free_y: (fn(&'x u32),
LL | | fn(&'y u32)) }
   | |______________- in this macro invocation
   |
   = help: consider adding the following bound: `'x: 'y`
   = note: this error originates in the macro `check` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error