warning: function cannot return without recursing
  --> $DIR/issue-103599.rs:5:1
   |
LL | fn wrap(x: impl T) -> impl T {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
LL |
LL |     wrap(wrap(x))
   |          ------- recursive call site
   |
   = help: a `loop` may express intention better if this is on purpose
   = note: `#[warn(unconditional_recursion)]` on by default

warning: 1 warning emitted