src/test/compile-fail/borrowck/borrowck-union-borrow-nested.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 // ignore-tidy-linelength
  12
  13 #![feature(untagged_unions)]
  14
  15 #[derive(Clone, Copy)]
  16 struct S {
  17     a: u8,
  18     b: u16,
  19 }
  20
  21 #[derive(Clone, Copy)]
  22 union U {
  23     s: S,
  24     c: u32,
  25 }
  26
  27 fn main() {
  28     unsafe {
  29         {
  30             let mut u = U { s: S { a: 0, b: 1 } };
  31             let ra = &mut u.s.a;
  32             let b = u.s.b; // OK
  33         }
  34         {
  35             let mut u = U { s: S { a: 0, b: 1 } };
  36             let ra = &mut u.s.a;
  37             let b = u.c; //~ ERROR cannot use `u.c` because it was mutably borrowed
  38         }
  39     }
  40 }