error[E0308]: mismatched types
  --> $DIR/diverging-fn-tail-35849.rs:3:9
   |
LL | fn assert_sizeof() -> ! {
   |                       - expected `!` because of return type
LL |     unsafe {
LL |         ::std::mem::transmute::<f64, [u8; 8]>(panic!())
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `!`, found `[u8; 8]`
   |
   = note: expected type `!`
             found array `[u8; 8]`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0308`.