tests/ui/generator/yielding-in-match-guards.rs

   1 // build-pass
   2 // edition:2018
   3
   4 // This test is derived from
   5 // https://github.com/rust-lang/rust/issues/72651#issuecomment-668720468
   6
   7 // This test demonstrates that, in `async fn g()`,
   8 // indeed a temporary borrow `y` from `x` is live
   9 // while `f().await` is being evaluated.
  10 // Thus, `&'_ u8` should be included in type signature
  11 // of the underlying generator.
  12
  13 #![feature(if_let_guard)]
  14
  15 async fn f() -> u8 { 1 }
  16 async fn foo() -> [bool; 10] { [false; 10] }
  17
  18 pub async fn g(x: u8) {
  19     match x {
  20         y if f().await == y => (),
  21         _ => (),
  22     }
  23 }
  24
  25 // #78366: check the reference to the binding is recorded even if the binding is not autorefed
  26
  27 async fn h(x: usize) {
  28     match x {
  29         y if foo().await[y] => (),
  30         _ => (),
  31     }
  32 }
  33
  34 async fn i(x: u8) {
  35     match x {
  36         y if f().await == y + 1 => (),
  37         _ => (),
  38     }
  39 }
  40
  41 async fn j(x: u8) {
  42     match x {
  43         y if let (1, 42) = (f().await, y) => (),
  44         _ => (),
  45     }
  46 }
  47
  48 fn main() {
  49     let _ = g(10);
  50     let _ = h(9);
  51     let _ = i(8);
  52     let _ = j(7);
  53 }