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Return a Pin from SyncOnceCell::get_or_init_pin.

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This commit is contained in:
Mara Bos 2020-10-10 20:14:33 +02:00 • committed by Mark Rousskov
parent 91cb6283d8
commit 4137adeba3
1 changed files with 7 additions and 4 deletions
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11
library/std/src/lazy.rs
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@ -321,13 +321,15 @@ impl<T> SyncOnceCell<T> {
/// It is an error to reentrantly initialize the cell from `f`. The exact
/// outcome is unspecified. Current implementation deadlocks, but this may
/// be changed to a panic in the future.
pub(crate) fn get_or_init_pin<F, G>(self: Pin<&Self>, f: F, g: G) -> &T
pub(crate) fn get_or_init_pin<F, G>(self: Pin<&Self>, f: F, g: G) -> Pin<&T>
where
F: FnOnce() -> T,
G: FnOnce(Pin<&mut T>),
{
if let Some(value) = self.get_ref().get() {
return value;
// SAFETY: The inner value was already initialized, and will not be
// moved anymore.
return unsafe { Pin::new_unchecked(value) };
}
let slot = &self.value;
@ -345,8 +347,9 @@ impl<T> SyncOnceCell<T> {
g(unsafe { Pin::new_unchecked(value) });
});
// SAFETY: The inner value has been initialized.
unsafe { self.get_ref().get_unchecked() }
// SAFETY: The inner value has been initialized, and will not be moved
// anymore.
unsafe { Pin::new_unchecked(self.get_ref().get_unchecked()) }
}
/// Consumes the `SyncOnceCell`, returning the wrapped value. Returns