src/test/compile-fail/borrowck-lend-flow-if.rs

   1 // Copyright 2012 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 // Note: the borrowck analysis is currently flow-insensitive.
  12 // Therefore, some of these errors are marked as spurious and could be
  13 // corrected by a simple change to the analysis.  The others are
  14 // either genuine or would require more advanced changes.  The latter
  15 // cases are noted.
  16
  17 #![feature(box_syntax)]
  18
  19 fn borrow(_v: &isize) {}
  20 fn borrow_mut(_v: &mut isize) {}
  21 fn cond() -> bool { panic!() }
  22 fn for_func<F>(_f: F) where F: FnOnce() -> bool { panic!() }
  23 fn produce<T>() -> T { panic!(); }
  24
  25 fn inc(v: &mut Box<isize>) {
  26     *v = box() (**v + 1);
  27 }
  28
  29 fn pre_freeze_cond() {
  30     // In this instance, the freeze is conditional and starts before
  31     // the mut borrow.
  32
  33     let mut v: Box<_> = box 3;
  34     let _w;
  35     if cond() {
  36         _w = &v;
  37     }
  38     borrow_mut(&mut *v); //~ ERROR cannot borrow
  39 }
  40
  41 fn pre_freeze_else() {
  42     // In this instance, the freeze and mut borrow are on separate sides
  43     // of the if.
  44
  45     let mut v: Box<_> = box 3;
  46     let _w;
  47     if cond() {
  48         _w = &v;
  49     } else {
  50         borrow_mut(&mut *v);
  51     }
  52 }
  53
  54 fn main() {}