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Auto merge of #68066 - CAD97:stabilize-manuallydrop-take, r=Amanieu,Mark-Simulacrum

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Stabilize ManuallyDrop::take

Tracking issue: closes #55422
FCP merge: https://github.com/rust-lang/rust/issues/55422#issuecomment-572653619

Reclaims the doc improvements from closed #62198.

-----

Stable version is a simple change if necessary.

Proposal: [relnotes] (this changes how to best take advantage of `ManuallyDrop`, esp. wrt. `Drop::drop` and finalize-by-value members)
This commit is contained in:
bors 2020-01-20 20:11:20 +00:00
commit b5a3341f1b
2 changed files with 8 additions and 8 deletions
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15
src/libcore/mem/manually_drop.rs
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@ -87,27 +87,28 @@ impl<T> ManuallyDrop<T> {
slot.value slot.value
} }
/// Takes the contained value out. /// Takes the value from the `ManuallyDrop<T>` container out.
/// ///
/// This method is primarily intended for moving out values in drop. /// This method is primarily intended for moving out values in drop.
/// Instead of using [`ManuallyDrop::drop`] to manually drop the value, /// Instead of using [`ManuallyDrop::drop`] to manually drop the value,
/// you can use this method to take the value and use it however desired. /// you can use this method to take the value and use it however desired.
/// `Drop` will be invoked on the returned value following normal end-of-scope rules.
/// ///
/// If you have ownership of the container, you can use [`ManuallyDrop::into_inner`] instead. /// Whenever possible, it is preferrable to use [`into_inner`][`ManuallyDrop::into_inner`]
/// instead, which prevents duplicating the content of the `ManuallyDrop<T>`.
/// ///
/// # Safety /// # Safety
/// ///
/// This function semantically moves out the contained value without preventing further usage. /// This function semantically moves out the contained value without preventing further usage,
/// It is up to the user of this method to ensure that this container is not used again. /// leaving the state of this container unchanged.
/// It is your responsibility to ensure that this `ManuallyDrop` is not used again.
/// ///
/// [`ManuallyDrop::drop`]: #method.drop /// [`ManuallyDrop::drop`]: #method.drop
/// [`ManuallyDrop::into_inner`]: #method.into_inner /// [`ManuallyDrop::into_inner`]: #method.into_inner
#[must_use = "if you don't need the value, you can use `ManuallyDrop::drop` instead"] #[must_use = "if you don't need the value, you can use `ManuallyDrop::drop` instead"]
#[unstable(feature = "manually_drop_take", issue = "55422")] #[stable(feature = "manually_drop_take", since = "1.42.0")]
#[inline] #[inline]
pub unsafe fn take(slot: &mut ManuallyDrop<T>) -> T { pub unsafe fn take(slot: &mut ManuallyDrop<T>) -> T {
ManuallyDrop::into_inner(ptr::read(slot)) ptr::read(&slot.value)
} }
} }

1
src/libstd/lib.rs
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@ -275,7 +275,6 @@
#![feature(link_args)] #![feature(link_args)]
#![feature(linkage)] #![feature(linkage)]
#![feature(log_syntax)] #![feature(log_syntax)]
#![feature(manually_drop_take)]
#![feature(maybe_uninit_ref)] #![feature(maybe_uninit_ref)]
#![feature(maybe_uninit_slice)] #![feature(maybe_uninit_slice)]
#![feature(needs_panic_runtime)] #![feature(needs_panic_runtime)]