tests/ui/borrowck/borrowck-union-borrow-nested.rs

   1 #[derive(Clone, Copy)]
   2 struct S {
   3     a: u8,
   4     b: u16,
   5 }
   6
   7 #[derive(Clone, Copy)]
   8 union U {
   9     s: S,
  10     c: u32,
  11 }
  12
  13 fn main() {
  14     unsafe {
  15         {
  16             let mut u = U { s: S { a: 0, b: 1 } };
  17             let ra = &mut u.s.a;
  18             let b = u.s.b; // OK
  19             ra.use_mut();
  20         }
  21         {
  22             let mut u = U { s: S { a: 0, b: 1 } };
  23             let ra = &mut u.s.a;
  24             let b = u.c; //~ ERROR cannot use `u.c` because it was mutably borrowed
  25             ra.use_mut();
  26         }
  27     }
  28 }
  29
  30 trait Fake { fn use_mut(&mut self) { } fn use_ref(&self) { }  }
  31 impl<T> Fake for T { }