error[E0070]: invalid left-hand side of assignment
  --> $DIR/assign-non-lval-derefmut.rs:5:23
   |
LL |     x.lock().unwrap() = 2;
   |     ----------------- ^
   |     |
   |     cannot assign to this expression
   |
help: consider dereferencing here to assign to the mutably borrowed value
   |
LL |     *x.lock().unwrap() = 2;
   |     +

error[E0368]: binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
  --> $DIR/assign-non-lval-derefmut.rs:7:5
   |
LL |     x.lock().unwrap() += 1;
   |     -----------------^^^^^
   |     |
   |     cannot use `+=` on type `MutexGuard<'_, usize>`
   |
help: `+=` can be used on `usize` if you dereference the left-hand side
   |
LL |     *x.lock().unwrap() += 1;
   |     +

error[E0308]: mismatched types
  --> $DIR/assign-non-lval-derefmut.rs:11:9
   |
LL |     let mut y = x.lock().unwrap();
   |                 ----------------- expected due to this value
LL |     y = 2;
   |         ^ expected struct `MutexGuard`, found integer
   |
   = note: expected struct `MutexGuard<'_, usize>`
                found type `{integer}`
help: consider dereferencing here to assign to the mutably borrowed value
   |
LL |     *y = 2;
   |     +

error[E0368]: binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
  --> $DIR/assign-non-lval-derefmut.rs:13:5
   |
LL |     y += 1;
   |     -^^^^^
   |     |
   |     cannot use `+=` on type `MutexGuard<'_, usize>`
   |
help: `+=` can be used on `usize` if you dereference the left-hand side
   |
LL |     *y += 1;
   |     +

error: aborting due to 4 previous errors

Some errors have detailed explanations: E0070, E0308, E0368.
For more information about an error, try `rustc --explain E0070`.