3 The tracking issue for this feature is: [#24111]
5 [#24111]: https://github.com/rust-lang/rust/issues/24111
7 ------------------------
9 The `const_fn` feature allows marking free functions and inherent methods as
10 `const`, enabling them to be called in constants contexts, with constant
18 const fn double(x: i32) -> i32 {
23 const TEN: i32 = double(FIVE);