1 error[E0277]: `&mut ()` is not a tuple
2 --> $DIR/issue-57404.rs:6:41
4 LL | handlers.unwrap().as_mut().call_mut(&mut ());
5 | -------- ^^^^^^^ the trait `Tuple` is not implemented for `&mut ()`
7 | required by a bound introduced by this call
9 note: required by a bound in `call_mut`
10 --> $SRC_DIR/core/src/ops/function.rs:LL:COL
11 help: consider removing the leading `&`-reference
13 LL - handlers.unwrap().as_mut().call_mut(&mut ());
14 LL + handlers.unwrap().as_mut().call_mut(());
17 error: aborting due to previous error
19 For more information about this error, try `rustc --explain E0277`.