error[E0061]: this function takes 2 arguments but 1 argument was supplied
  --> $DIR/issue-18819.rs:16:5
   |
LL |     print_x(X);
   |     ^^^^^^^ - supplied 1 argument
   |     |
   |     expected 2 arguments
   |
note: function defined here
  --> $DIR/issue-18819.rs:11:4
   |
LL | fn print_x(_: &dyn Foo<Item=bool>, extra: &str) {
   |    ^^^^^^^ ----------------------  -----------

error: aborting due to previous error

For more information about this error, try `rustc --explain E0061`.