error[E0277]: the trait bound `u8: Pattern` is not satisfied
  --> $DIR/assoc-fn-bound-root-obligation.rs:2:20
   |
LL |     s.strip_suffix(b'\n').unwrap_or(s)
   |       ------------ ^^^^^ the trait `FnMut(char)` is not implemented for `u8`
   |       |
   |       required by a bound introduced by this call
   |
   = help: the following other types implement trait `Pattern`:
             &'b String
             &'b [char; N]
             &'b [char]
             &'b str
             &'c &'b str
             [char; N]
             char
   = note: required for `u8` to implement `Pattern`
note: required by a bound in `core::str::<impl str>::strip_suffix`
  --> $SRC_DIR/core/src/str/mod.rs:LL:COL

error: aborting due to 1 previous error

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