error: functions with the "rust-call" ABI must take a single non-self argument that is a tuple
  --> $DIR/overloaded-calls-nontuple.rs:11:5
   |
LL |     extern "rust-call" fn call_mut(&mut self, z: isize) -> isize {
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: functions with the "rust-call" ABI must take a single non-self argument that is a tuple
  --> $DIR/overloaded-calls-nontuple.rs:19:5
   |
LL |     extern "rust-call" fn call_once(mut self, z: isize) -> isize { self.call_mut(z) }
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0059]: cannot use call notation; the first type parameter for the function trait is neither a tuple nor unit
  --> $DIR/overloaded-calls-nontuple.rs:28:10
   |
LL |     drop(s(3))
   |          ^^^^

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0059`.