Struct tokio_util::util::maybe_dangling::MaybeDangling

#[repr(transparent)]
pub(crate) struct MaybeDangling<T>(MaybeUninit<T>);

A wrapper type that tells the compiler that the contents might not be valid.

This is necessary mainly when T contains a reference. In that case, the compiler will sometimes assume that the reference is always valid; in some cases it will assume this even after the destructor of T runs. For example, when a reference is used as a function argument, then the compiler will assume that the reference is valid until the function returns, even if the reference is destroyed during the function. When the reference is used as part of a self-referential struct, that assumption can be false. Wrapping the reference in this type prevents the compiler from making that assumption.

Invariants

The MaybeUninit will always contain a valid value until the destructor runs.

Tuple Fields

0: MaybeUninit<T>

Implementations

impl<T> MaybeDangling<T>

pub(crate) fn new(inner: T) -> Self

Trait Implementations

impl<T> Drop for MaybeDangling<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<F: Future> Future for MaybeDangling<F>

type Output = <F as Future>::Output

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.