tests/ui/unsized/issue-97732.rs

   1 // check-pass
   2
   3 #![feature(coerce_unsized)]
   4
   5 // Ensure that unsizing structs that contain ZSTs at non-zero offsets don't ICE
   6
   7 use std::ops::CoerceUnsized;
   8
   9 #[repr(C)]
  10 pub struct BoxWithZstTail<T: ?Sized>(Box<T>, ());
  11
  12 impl<S: ?Sized, T: ?Sized> CoerceUnsized<BoxWithZstTail<T>> for BoxWithZstTail<S> where
  13     Box<S>: CoerceUnsized<Box<T>>
  14 {
  15 }
  16
  17 pub fn noop_dyn_upcast_with_zst_tail(
  18     b: BoxWithZstTail<dyn ToString + Send>,
  19 ) -> BoxWithZstTail<dyn ToString> {
  20     b
  21 }
  22
  23 fn main() {
  24     let original = "foo";
  25     let boxed = BoxWithZstTail(Box::new(original) as Box<dyn ToString + Send>, ());
  26     let noop_upcasted = noop_dyn_upcast_with_zst_tail(boxed);
  27     assert_eq!(original, noop_upcasted.0.to_string());
  28 }