use std::mem::MaybeUninit; fn main() { let fut = async {}; let cast: [MaybeUninit<u8>; 1] = unsafe { std::mem::transmute(fut) }; }

error[E0391]: cycle detected when type-checking `main` --> src/main.rs:3:1 | 3 | fn main() { | ^^^^^^^^^ | = note: ...which requires computing layout of `{async block@src/main.rs:4:15: 4:23}`... note: ...which requires optimizing MIR for `main::{closure#0}`... --> src/main.rs:4:15 | 4 | let fut = async {}; | ^^^^^^^^ note: ...which requires elaborating drops for `main::{closure#0}`... --> src/main.rs:4:15 | 4 | let fut = async {}; | ^^^^^^^^ note: ...which requires coroutine witness types for `main::{closure#0}`... --> src/main.rs:4:15 | 4 | let fut = async {}; | ^^^^^^^^ note: ...which requires promoting constants in MIR for `main::{closure#0}`... --> src/main.rs:4:15 | 4 | let fut = async {}; | ^^^^^^^^ note: ...which requires checking if `main::{closure#0}` contains FFI-unwind calls... --> src/main.rs:4:15 | 4 | let fut = async {}; | ^^^^^^^^ note: ...which requires building MIR for `main::{closure#0}`... --> src/main.rs:4:15 | 4 | let fut = async {}; | ^^^^^^^^ note: ...which requires match-checking `main::{closure#0}`... --> src/main.rs:4:15 | 4 | let fut = async {}; | ^^^^^^^^ note: ...which requires type-checking `main::{closure#0}`... --> src/main.rs:4:15 | 4 | let fut = async {}; | ^^^^^^^^ = note: ...which again requires type-checking `main`, completing the cycle = note: cycle used when running analysis passes on this crate = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information