struct Unused<T>(PhantomData<T>);Available on crate feature
alloc and (crate features formatting or parsing) only.Expand description
A value that may be used in the future, but currently is not.
This struct exists so that data can semantically be passed around without actually passing it around. This way the data still exists if it is needed in the future.
Tuple Fields§
§0: PhantomData<T>Auto Trait Implementations§
impl<T> Freeze for Unused<T>where
PhantomData<T>: Freeze,
impl<T> RefUnwindSafe for Unused<T>where
PhantomData<T>: RefUnwindSafe,
impl<T> Send for Unused<T>where
PhantomData<T>: Send,
impl<T> Sync for Unused<T>where
PhantomData<T>: Sync,
impl<T> Unpin for Unused<T>where
PhantomData<T>: Unpin,
impl<T> UnsafeUnpin for Unused<T>where
PhantomData<T>: UnsafeUnpin,
impl<T> UnwindSafe for Unused<T>where
PhantomData<T>: UnwindSafe,
Blanket Implementations§
Source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
Source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
Source§impl<T> SizeHint for Twhere
T: ?Sized,
impl<T> SizeHint for Twhere
T: ?Sized,
Source§default fn lower_bound(&self) -> usize
default fn lower_bound(&self) -> usize
🔬This is a nightly-only experimental API. (
core_io_internals)Returns a lower bound on the number of elements this container-like item
contains.
For example, an array
[u8; 12] could return any value between 0 and
12 inclusively as a correct implementation. Read moreSource§impl<T> SizedTypeProperties for T
impl<T> SizedTypeProperties for T
Source§#[doc(hidden)]const SIZE: usize = _
#[doc(hidden)]const SIZE: usize = _
🔬This is a nightly-only experimental API. (
sized_type_properties)Source§#[doc(hidden)]const ALIGN: usize = _
#[doc(hidden)]const ALIGN: usize = _
🔬This is a nightly-only experimental API. (
sized_type_properties)Source§#[doc(hidden)]const ALIGNMENT: Alignment = _
#[doc(hidden)]const ALIGNMENT: Alignment = _
🔬This is a nightly-only experimental API. (
ptr_alignment_type)Source§#[doc(hidden)]const IS_ZST: bool = _
#[doc(hidden)]const IS_ZST: bool = _
🔬This is a nightly-only experimental API. (
sized_type_properties)Source§#[doc(hidden)]const LAYOUT: Layout = _
#[doc(hidden)]const LAYOUT: Layout = _
🔬This is a nightly-only experimental API. (
sized_type_properties)Source§#[doc(hidden)]const MAX_SLICE_LEN: usize = _
#[doc(hidden)]const MAX_SLICE_LEN: usize = _
🔬This is a nightly-only experimental API. (
sized_type_properties)The largest safe length for a
[Self]. Read more