Awaiting a function returning a never type does not warn for unreachable code after the await

[ungrichtepfl]

Code

pub async fn endless_async() -> ! {
    loop {
        tokio::time::sleep(tokio::time::Duration::from_secs(1)).await;
    }
}

pub async fn should_warn() {
    endless_async().await;
    println!("This code is unreachable");  // no warning about unreachable code
}

pub fn endless() -> ! {
    loop {
        std::thread::sleep(std::time::Duration::from_secs(1));
    }
}

pub fn warns() {
    endless();
    println!("This code is unreachable");  // warning: unreachable statement
}

Current output

warning: unreachable statement
  --> src/lib.rs:20:5
   |
19 |     endless();
   |     --------- any code following this expression is unreachable
20 |     println!("This code is unreachable");
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
   |
   = note: `#[warn(unreachable_code)]` on by default
   = note: this warning originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)

Desired output

warning: unreachable statement
  --> src/lib.rs:9:5
   |
 8 |     endless_async().await;
   |     --------------------- any code following this expression is unreachable
 9 |     println!("This code is unreachable");
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
   |
   = note: `#[warn(unreachable_code)]` on by default
   = note: this warning originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
warning: unreachable statement
  --> src/lib.rs:20:5
   |
19 |     endless();
   |     --------- any code following this expression is unreachable
20 |     println!("This code is unreachable");
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
   |
   = note: `#[warn(unreachable_code)]` on by default
   = note: this warning originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)

Rationale and extra context

No response

Other cases

No response

Rust Version

rustc 1.80.0 (051478957 2024-07-21)
binary: rustc
commit-hash: 051478957371ee0084a7c0913941d2a8c4757bb9
commit-date: 2024-07-21
host: x86_64-unknown-linux-gnu
release: 1.80.0
LLVM version: 18.1.7

Anything else?

Same behaviour with the current nightly version:

rustc 1.82.0-nightly (f8060d282 2024-07-30)
binary: rustc
commit-hash: f8060d282d42770fadd73905e3eefb85660d3278
commit-date: 2024-07-30
host: x86_64-unknown-linux-gnu
release: 1.82.0-nightly
LLVM version: 18.1.7

[compiler-errors]

I'll take a look at this 👀

This almost certainly has something to do with the await desugaring into a poll loop