warning: function cannot return without recursing
  --> $DIR/recursive.rs:3:1
   |
LL | const fn f<T>(x: T) {
   | ^^^^^^^^^^^^^^^^^^^ cannot return without recursing
LL |     f(x);
   |     ---- recursive call site
   |
   = note: `#[warn(unconditional_recursion)]` on by default
   = help: a `loop` may express intention better if this is on purpose

error: any use of this value will cause an error
  --> $DIR/recursive.rs:4:5
   |
LL |     f(x);
   |     ^^^^
   |     |
   |     reached the configured maximum number of stack frames
   |     inside `f::<i32>` at $DIR/recursive.rs:4:5
   |     [... 126 additional calls inside `f::<i32>` at $DIR/recursive.rs:4:5 ...]
   |     inside `X` at $DIR/recursive.rs:9:15
...
LL | const X: () = f(1);
   | -------------------
   |
   = note: `#[deny(const_err)]` on by default
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>

error: aborting due to previous error; 1 warning emitted