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PhantomData layout guarantees

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Joshua Liebow-Feeser 2022-11-06 16:08:05 -08:00 committed by GitHub
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commit 72a9029b84
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6
library/core/src/marker.rs
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@ -621,6 +621,12 @@ impl<T: ?Sized> !Sync for *mut T {}
/// (ideally) or `PhantomData<*const T>` (if no lifetime applies), so /// (ideally) or `PhantomData<*const T>` (if no lifetime applies), so
/// as not to indicate ownership. /// as not to indicate ownership.
/// ///
/// ## Layout
///
/// For all `T`, the following are guaranteed:
/// * `size_of::<PhantomData<T>>() == 0`
/// * `align_of::<PhantomData<T>>() == 1`
///
/// [drop check]: ../../nomicon/dropck.html /// [drop check]: ../../nomicon/dropck.html
#[lang = "phantom_data"] #[lang = "phantom_data"]
#[stable(feature = "rust1", since = "1.0.0")] #[stable(feature = "rust1", since = "1.0.0")]