src/test/ui/typeck/assign-non-lval-derefmut.rs

   1 // run-rustfix
   2
   3 fn main() {
   4     let x = std::sync::Mutex::new(1usize);
   5     x.lock().unwrap() = 2;
   6     //~^ ERROR invalid left-hand side of assignment
   7     x.lock().unwrap() += 1;
   8     //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
   9
  10     let mut y = x.lock().unwrap();
  11     y = 2;
  12     //~^ ERROR mismatched types
  13     y += 1;
  14     //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
  15 }