pub struct AssertUnwindSafe<T>(pub T);
A simple wrapper around a type to assert that it is unwind safe.
When using catch_unwind it may be the case that some of the closed over variables are not unwind safe. For example if &mut T is captured the compiler will generate a warning indicating that it is not unwind safe. It may not be the case, however, that this is actually a problem due to the specific usage of catch_unwind if unwind safety is specifically taken into account. This wrapper struct is useful for a quick and lightweight annotation that a variable is indeed unwind safe.
One way to use AssertUnwindSafe is to assert that the entire closure itself is unwind safe, bypassing all checks for all variables:
use std::panic::{self, AssertUnwindSafe};
let mut variable = 4;
// This code will not compile because the closure captures `&mut variable`
// which is not considered unwind safe by default.
// panic::catch_unwind(|| {
// variable += 3;
// });
// This, however, will compile due to the `AssertUnwindSafe` wrapper
let result = panic::catch_unwind(AssertUnwindSafe(|| {
variable += 3;
}));
// ...Wrapping the entire closure amounts to a blanket assertion that all captured variables are unwind safe. This has the downside that if new captures are added in the future, they will also be considered unwind safe. Therefore, you may prefer to just wrap individual captures, as shown below. This is more annotation, but it ensures that if a new capture is added which is not unwind safe, you will get a compilation error at that time, which will allow you to consider whether that new capture in fact represent a bug or not.
use std::panic::{self, AssertUnwindSafe};
let mut variable = 4;
let other_capture = 3;
let result = {
let mut wrapper = AssertUnwindSafe(&mut variable);
panic::catch_unwind(move || {
**wrapper += other_capture;
})
};
// ...impl<T: Debug> Debug for AssertUnwindSafe<T>[src]1.16.0
impl<T> Deref for AssertUnwindSafe<T>[src]
type Target = TThe resulting type after dereferencing.
fn deref(&self) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> DerefMut for AssertUnwindSafe<T>[src]
fn deref_mut(&mut self) -> &mut TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<R, F: FnOnce() -> R> FnOnce() for AssertUnwindSafe<F>[src]
type Output = RThe returned type after the call operator is used.
extern "rust-call" fn call_once(self, _args: ()) -> R[src]
impl<F: Future> Future for AssertUnwindSafe<F>[src]1.36.0
type Output = F::OutputThe type of value produced on completion.
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>[src]
impl<T> RefUnwindSafe for AssertUnwindSafe<T>[src]
impl<T> UnwindSafe for AssertUnwindSafe<T>[src]
impl<T> Send for AssertUnwindSafe<T> where
T: Send, impl<T> Sync for AssertUnwindSafe<T> where
T: Sync, impl<T> Unpin for AssertUnwindSafe<T> where
T: Unpin, impl<T> Any for T where
T: 'static + ?Sized, [src]
impl<T> Borrow<T> for T where
T: ?Sized, [src]
fn borrow(&self) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> BorrowMut<T> for T where
T: ?Sized, [src]
fn borrow_mut(&mut self) -> &mut TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> From<T> for T[src]
impl<T, U> Into<U> for T where
U: From<T>, [src]
impl<F> IntoFuture for F where
F: Future, [src]
type Output = <F as Future>::OutputThe output that the future will produce on completion.
type Future = FWhich kind of future are we turning this into?
fn into_future(self) -> <F as IntoFuture>::Future[src]
impl<T, U> TryFrom<U> for T where
U: Into<T>, [src]
type Error = InfallibleThe type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>[src]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>, [src]
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/panic/struct.AssertUnwindSafe.html