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#126482

@rustbot label +F-async_drop

cc @zetanumbers

The future and ctor fields aren't actually used, and the way they are extracted is obviously wrong – swapping the order of the items in the source code will give wrong results.

Although I should notice such an error easily, could you please provide failing code sample? Adding a test case would be the best.

There is no failing sample, because you never use these fields for anything. However:

1. Add a debug!(?future, ?ctor);.
2. Write the simplest possible AsyncDrop impl:

#![feature(async_drop)]
use std::future::{AsyncDrop, Ready};
use std::pin::Pin;

struct Foo;

impl AsyncDrop for Foo {
    type Dropper<'a> = Ready<()>;

    fn async_drop(self: Pin<&mut Self>) -> Self::Dropper<'_> {
        todo!()
    }
}

3. Observe that the output of the debug! statement makes sense.
4. Swap the two associated items as follows:

impl AsyncDrop for Foo {
    fn async_drop(self: Pin<&mut Self>) -> Self::Dropper<'_> {
        todo!()
    }

    type Dropper<'a> = Ready<()>;
}

5. Observe that the output of the debug! statement is now wrong.

Holy! Now I remember. Thanks for fixing it. LGTM @petrochenkov

r? @petrochenkov
@bors r+ rollup

📌 Commit a2618e1 has been approved by petrochenkov

It is now in the queue for this repository.