src/test/ui/mir/mir-inlining/ice-issue-77564.rs

   1 // run-pass
   2 // compile-flags:-Zmir-opt-level=3
   3
   4 use std::mem::MaybeUninit;
   5 const N: usize = 2;
   6
   7 trait CollectArray<A>: Iterator<Item = A> {
   8     fn inner_array(&mut self) -> [A; N];
   9     fn collect_array(&mut self) -> [A; N] {
  10         let result = self.inner_array();
  11         assert!(self.next().is_none());
  12         result
  13     }
  14 }
  15
  16 impl<A, I: ?Sized> CollectArray<A> for I
  17 where
  18     I: Iterator<Item = A>,
  19 {
  20     fn inner_array(&mut self) -> [A; N] {
  21         let mut result: [MaybeUninit<A>; N] = unsafe { MaybeUninit::uninit().assume_init() };
  22         for (dest, item) in result.iter_mut().zip(self) {
  23             *dest = MaybeUninit::new(item);
  24         }
  25         let temp_ptr: *const [MaybeUninit<A>; N] = &result;
  26         unsafe { std::ptr::read(temp_ptr as *const [A; N]) }
  27     }
  28 }
  29
  30 fn main() {
  31     assert_eq!(
  32         [[1, 2], [3, 4]]
  33             .iter()
  34             .map(|row| row.iter().collect_array())
  35             .collect_array(),
  36         [[&1, &2], [&3, &4]]
  37     );
  38 }