await_holding_refcell_ref false negative when inside async block

[omni-corp]

Example code

use std::cell::RefCell;
use std::future::Future;

#[allow(unused)]
async fn foo(x: &RefCell<u32>, bar: impl Future<Output=()>) {
    async {
        let mut y = x.borrow_mut();
        *y += 1;
        bar.await;
    }.await;
}

When running cargo clippy -- -W clippy::pedantic expected the warning this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await. Instead no warning is produced. Removing the async block produces the warning as expected.

Meta

cargo clippy -V:
clippy 0.1.52 (acca8189 2021-03-13)

rustc -Vv:

rustc 1.52.0-nightly (acca81892 2021-03-13)
binary: rustc
commit-hash: acca818928654807ed3bc1ce0e97df118f8716c8
commit-date: 2021-03-13
host: x86_64-pc-windows-msvc
release: 1.52.0-nightly

[kellerb]

This false negative also occurs with await_holding_lock
https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=6e840ea9a1e3ce8231aa6c76db10b50f

async fn _hold_lock() {
    //async { // Uncomment this block and the clippy lint goes away
        let lock = parking_lot::Mutex::new(());
        let _guard = lock.lock();
        let () = async {}.await;
    //}.await
}