```rust fn main() { let x: u8 = 5; const Y: u8 = x; } ``` results in: ``` error[E0434]: can't capture dynamic environment in a fn item --> src/main.rs:3:19 | 3 | const Y: u8 = x; | ^ | = help: use the `|| { ... }` closure form instead error: aborting due to previous error ``` (which of course doesn't work — actually carrying out the suggestion results in the same suggestion).