Remove unnecessary (and incorrect) &mut cast in net-tokio#4691
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TheBlueMatt merged 1 commit intoJun 15, 2026
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The owned `Waker` wake method assumed it had the only reference to the sender as the `Waker` is owned at that point, however our `Waker`s can be `clone`d, leaving multiple references to the inner `Sender` (held in an `Arc`). Thus, the `&mut` cast is technically undefined behavior. However, as this patch demonstrates, its only use is in calling an `&self` method which derefs an internal `Arc` in tokio, so its highly unlikely to lead to miscompilation. Reported by Project Loupe.
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I've assigned @valentinewallace as a reviewer! |
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The change is minimal and correct: it converts an undefined-behavior No issues found. |
valentinewallace
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Jun 15, 2026
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👋 The first review has been submitted! Do you think this PR is ready for a second reviewer? If so, click here to assign a second reviewer. |
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Honestly not even sure this is worth backporting. |
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The owned
Wakerwake method assumed it had the only reference to the sender as theWakeris owned at that point, however ourWakers can becloned, leaving multiple references to the innerSender(held in anArc).Thus, the
&mutcast is technically undefined behavior. However, as this patch demonstrates, its only use is in calling an&selfmethod which derefs an internalArcin tokio, so its highly unlikely to lead to miscompilation.Reported by Project Loupe.