src/test/ui/nll/closure-requirements/escape-argument-callee.rs

   1 // Test closure that:
   2 //
   3 // - takes an argument `y` with lifetime `'a` (in the code, it's anonymous)
   4 // - stores `y` into another, longer-lived spot with lifetime `'b`
   5 //
   6 // Because `'a` and `'b` are two different, unrelated higher-ranked
   7 // regions with no relationship to one another, this is an error. This
   8 // error is reported by the closure itself and is not propagated to
   9 // its creator: this is because `'a` and `'b` are higher-ranked
  10 // (late-bound) regions and the closure is not allowed to propagate
  11 // additional where clauses between higher-ranked regions, only those
  12 // that appear free in its type (hence, we see it before the closure's
  13 // "external requirements" report).
  14
  15 // compile-flags:-Zverbose
  16
  17 #![feature(rustc_attrs)]
  18
  19 #[rustc_regions]
  20 fn test() {
  21     let x = 44;
  22     let mut p = &x;
  23
  24     {
  25         let y = 22;
  26         let mut closure = expect_sig(|p, y| *p = y);
  27         //~^ ERROR
  28         closure(&mut p, &y);
  29     }
  30
  31     deref(p);
  32 }
  33
  34 fn expect_sig<F>(f: F) -> F
  35     where F: FnMut(&mut &i32, &i32)
  36 {
  37     f
  38 }
  39
  40 fn deref(_p: &i32) { }
  41
  42 fn main() { }