Allow Arc::from_raw to be used with a pointer from Arc::as_ptr

[albertlarsan68]

Closes #106124

r? rust-lang/libs-api

@rustbot labels +A-docs +T-libs-api -T-libs

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[marmeladema]

What happens when an Arc built with a call to Arc::from_raw on a pointer obtained from Arc::as_ptr when it is dropped? Won't that decrement the strong count and potentially free the underlying object even though there are still Arcs alive for that same object?

https://play.rust-lang.org/?version=stable&mode=release&edition=2021&gist=f39f5c227412d4659d6a1edc9c3ac21e

I have always thought strong_count was always >= 1

EDIT: ok that won't free it because the strong count will wrap but then it might lead to leaks which is probably not unsound but a bit tricky to debug.

What's the real gain by allowing this?

[anden3]

Hello @albertlarsan68! Has there been any updates since the review posted above?

[bors]

☔ The latest upstream changes (presumably #89132) made this pull request unmergeable. Please resolve the merge conflicts.

[Dylan-DPC]

Closing this as inactive. Feel free to reöpen this pr or create a new pr if you get the time to work on this. Thanks