// edition:2018 #![warn(clippy::await_holding_refcell_ref)] use std::cell::RefCell; async fn bad(x: &RefCell<u32>) -> u32 { let b = x.borrow(); baz().await } async fn bad_mut(x: &RefCell<u32>) -> u32 { let b = x.borrow_mut(); baz().await } async fn good(x: &RefCell<u32>) -> u32 { { let b = x.borrow_mut(); let y = *b + 1; } baz().await; let b = x.borrow_mut(); 47 } async fn baz() -> u32 { 42 } async fn also_bad(x: &RefCell<u32>) -> u32 { let first = baz().await; let b = x.borrow_mut(); let second = baz().await; let third = baz().await; first + second + third } async fn less_bad(x: &RefCell<u32>) -> u32 { let first = baz().await; let b = x.borrow_mut(); let second = baz().await; drop(b); let third = baz().await; first + second + third } async fn not_good(x: &RefCell<u32>) -> u32 { let first = baz().await; let second = { let b = x.borrow_mut(); baz().await }; let third = baz().await; first + second + third } #[allow(clippy::manual_async_fn)] fn block_bad(x: &RefCell<u32>) -> impl std::future::Future<Output = u32> + '_ { async move { let b = x.borrow_mut(); baz().await } } fn main() { let rc = RefCell::new(100); good(&rc); bad(&rc); bad_mut(&rc); also_bad(&rc); less_bad(&rc); not_good(&rc); block_bad(&rc); }