error[E0792]: expected generic type parameter, found `&str`
  --> $DIR/recursive-ice-101862.rs:6:19
   |
LL | pub fn ice(x: impl AsRef<str>) -> impl IntoIterator<Item = ()> {
   |               --------------- this generic parameter must be used with a generic type parameter
LL |
LL |     vec![].append(&mut ice(x.as_ref()));
   |                   ^^^^^^^^^^^^^^^^^^^^

warning: function cannot return without recursing
  --> $DIR/recursive-ice-101862.rs:4:1
   |
LL | pub fn ice(x: impl AsRef<str>) -> impl IntoIterator<Item = ()> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
LL |
LL |     vec![].append(&mut ice(x.as_ref()));
   |                        --------------- recursive call site
   |
   = help: a `loop` may express intention better if this is on purpose
   = note: `#[warn(unconditional_recursion)]` on by default

error: aborting due to 1 previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0792`.