main()1 fn main() {
2     let mut value = 3;
3     let _borrow = &mut value;
4     let _sum = value + 1; //~ ERROR E0503
5     _borrow.use_mut();
6 }
7 
use_mut(&mut self)8 trait Fake { fn use_mut(&mut self) { } fn use_ref(&self) { }  }
9 impl<T> Fake for T { }
10