error[E0624]: associated function `foo` is private
  --> $DIR/private-impl-method.rs:20:7
   |
LL |         fn foo(&self) {}
   |         ------------- private associated function defined here
...
LL |     s.foo();
   |       ^^^ private associated function

error: aborting due to previous error

For more information about this error, try `rustc --explain E0624`.