error[E0277]: the trait bound `&Box<dyn Fn() -> i32>: Foo` is not satisfied
  --> $DIR/call-on-unimplemented-with-autoderef.rs:8:15
   |
LL |     needs_foo(x);
   |     --------- ^ the trait `Foo` is not implemented for `&Box<dyn Fn() -> i32>`
   |     |
   |     required by a bound introduced by this call
   |
note: required by a bound in `needs_foo`
  --> $DIR/call-on-unimplemented-with-autoderef.rs:5:22
   |
LL | fn needs_foo(_: impl Foo) {}
   |                      ^^^ required by this bound in `needs_foo`
help: use parentheses to call this trait object
   |
LL |     needs_foo(x());
   |                ++

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.