src/test/ui/nll/closure-requirements/escape-upvar-ref.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Test closure that:
  12 //
  13 // - captures a variable `y` by reference
  14 // - stores that reference to `y` into another, longer-lived place (`p`)
  15 //
  16 // Both of these are upvars of reference type (the capture of `y` is
  17 // of type `&'a i32`, the capture of `p` is of type `&mut &'b
  18 // i32`). The closure thus computes a relationship between `'a` and
  19 // `'b`.  This relationship is propagated to the closure creator,
  20 // which reports an error.
  21
  22 // compile-flags:-Zborrowck=mir -Zverbose
  23
  24 #![feature(rustc_attrs)]
  25
  26 #[rustc_regions]
  27 fn test() {
  28     let x = 44;
  29     let mut p = &x;
  30
  31     {
  32         let y = 22;
  33         let mut closure = || p = &y;
  34         //~^ ERROR `y` does not live long enough [E0597]
  35         closure();
  36     }
  37
  38     deref(p);
  39 }
  40
  41 fn deref(_p: &i32) { }
  42
  43 fn main() { }