Async drop fix for dropee from another crate (#140858)

[azhogin]

Fixes #140858.

For AsyncDestructor impl def id was wrongly kept as a LocalDefId, which causes crash when dropee is declared in another crate.

Also, potential problem found:
when user crate drops type with async drop in dependency crate, and user crate doesn't enable feature(async_drop), then sync drop version will be used.

Is it a problem? Do we need some notification about such situations?

[rustbot]

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[azhogin]

r? oli-obk

[oli-obk]

when user crate drops type with async drop in dependency crate, and user crate doesn't enable feature(async_drop), then sync drop version will be used.

Is it a problem? Do we need some notification about such situations?

I don't think it's a problem. I don't see a way around this except making crates that have async drop enabled infecting all crates that depend on it to also have it enabled. If there's an easy way to warn/error about it that you can see and that you think would be good, we can add it, but otherwise please just add a test explaining it.

[oli-obk]

@bors r+ rollup

[bors]

📌 Commit 7b2dcf2 has been approved by oli-obk

It is now in the queue for this repository.