1 In a `fn` type, a lifetime appears only in the return type,
2 and not in the arguments types.
4 Erroneous code example:
8 // Here, `'a` appears only in the return type:
9 let x: for<'a> fn() -> &'a i32;
13 To fix this issue, either use the lifetime in the arguments, or use
18 // Here, `'a` appears only in the return type:
19 let x: for<'a> fn(&'a i32) -> &'a i32;
20 let y: fn() -> &'static i32;
24 Note: The examples above used to be (erroneously) accepted by the
25 compiler, but this was since corrected. See [issue #33685] for more
28 [issue #33685]: https://github.com/rust-lang/rust/issues/33685