`impl AsyncDrop for &Foo / Pin<Foo>` should not compile

[theemathas]

The following code currently compiles. Clearly, it should not.

#![feature(async_drop)]

use std::future::AsyncDrop;
use std::pin::Pin;

struct Foo;

impl AsyncDrop for &Foo {
    async fn drop(self: Pin<&mut Self>) {}
}

impl AsyncDrop for Pin<Foo> {
    async fn drop(self: Pin<&mut Self>) {}
}

Meta

Reproducible on the playground with 1.90.0-nightly (2025-07-08 ab68b0fb26485ab1fa69)

@rustbot labels +F-async_drop

[compiler-errors]

similar to that other drop coherence bug with fundamental types