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#[derive(Clone, Copy)]
struct S {
a: u8,
b: u16,
}
#[derive(Clone, Copy)]
union U {
s: S,
c: u32,
}
fn main() {
unsafe {
{
let mut u = U { s: S { a: 0, b: 1 } };
let ra = &mut u.s.a;
let b = u.s.b; // OK
ra.use_mut();
}
{
let mut u = U { s: S { a: 0, b: 1 } };
let ra = &mut u.s.a;
let b = u.c; //~ ERROR cannot use `u.c` because it was mutably borrowed
ra.use_mut();
}
}
}
trait Fake { fn use_mut(&mut self) { } fn use_ref(&self) { } }
impl<T> Fake for T { }
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