src/test/compile-fail/hrtb-identity-fn-borrows.rs

   1 // Copyright 2014 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 that the `'a` in the where clause correctly links the region
  12 // of the output to the region of the input.
  13
  14 trait FnLike<A,R> {
  15     fn call(&self, arg: A) -> R;
  16 }
  17
  18 fn call_repeatedly<F>(f: F)
  19     where F : for<'a> FnLike<&'a isize, &'a isize>
  20 {
  21     // Result is stored: cannot re-assign `x`
  22     let mut x = 3;
  23     let y = f.call(&x);
  24     x = 5; //~ ERROR cannot assign
  25
  26     // Result is not stored: can re-assign `x`
  27     let mut x = 3;
  28     f.call(&x);
  29     f.call(&x);
  30     f.call(&x);
  31     x = 5;
  32 }
  33
  34 fn main() {
  35 }