Don't inherit Send from parking_lot::*Guard #4359
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Darksonn
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hawkw
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Dec 30, 2021
tokio/src/loom/std/parking_lot.rs
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| pub(crate) struct Mutex<T: ?Sized>(PhantomData<std::sync::Mutex<T>>, parking_lot::Mutex<T>); | ||
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| #[derive(Debug)] | ||
| pub(crate) struct RwLock<T>(parking_lot::RwLock<T>); | ||
| pub(crate) struct RwLock<T>(PhantomData<std::sync::RwLock<T>>, parking_lot::RwLock<T>); |
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i have a slight preference for either making these named fields, or breaking them across multiple lines like we do with the guard types...this feels like a lot for one line. not a blocker though.
jonhoo
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Dec 30, 2021
Noah-Kennedy
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Dec 31, 2021
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Currently our
tokio::sync::watch::Reftype can becomeSendif Tokio is compiled with theparking_lotfeature andparking_lotis compiled with itssend_guardfeature. This PR will prevent thesend_guardfeature from affecting whether Tokio types areSendor not.Strictly speaking, this PR is a breaking change, however I believe we should make the change regardless. As it stands now, the
parking_lotcrate is in our public API, and if don't want to make this change, then we should also commit to never upgradingparking_lotbeyond0.11.x, as such an upgrade would be also be a breaking change for the same reasons.I don't think many people will be affected by this. Anyone who is affected is probably holding a
tokio::sync::watch::Refalive across an.await, which is always incorrect.The first commit in this PR adds a test to CI that should catch this in the future. The commit is first so we can see the test fail without the change. The test relies on
tokio/tokio/tests/async_send_sync.rs.