Feature gate: #![feature(const_convert)]
This is a tracking issue for constifying some conversions (see #87852 for numeric conversions). Among other things this enables using the ?-operator on Option and Result in const contexts for trivial conversions. Note that this does not add any new implementations, it only constifies the existing ones.
Simple example:
const fn foo() -> Result<(), FooError> {
let bar = try_thing()?; // A function that returns Result<_, FooError>
do_stuff_with(bar)?; // A function that returns Result<_, FooError>
Ok(())
}Public API
Constifies the following impls
impl<T, U> const Into<U> for T where U: ~const From<T>;
impl<T> const From<T> for T;
impl<T> const ops::Try for Option<T>;
impl<T> const ops::FromResidual for Option<T>;
impl<T, E> const ops::Try for Result<T, E>;
impl<T, E, F> const ops::FromResidual<Result<convert::Infallible, E>> for Result<T, F> where F: ~const From<E>;
impl<T: ?Sized, U: ?Sized> const AsRef<U> for &T where T: ~const AsRef<U>;
impl<T: ?Sized, U: ?Sized> const AsRef<U> for &mut T where T: ~const AsRef<U>;
impl<T: ?Sized, U: ?Sized> const AsMut<U> for &mut T where T: ~const AsMut<U>;
impl<T, U> const TryInto<U> for T where U: ~const TryFrom<T>;
impl<T, U> const TryFrom<U> for T where U: ~const Into<T>;
Steps / History
Unresolved Questions
Feature gate:
#![feature(const_convert)]This is a tracking issue for constifying some conversions (see #87852 for numeric conversions). Among other things this enables using the
?-operator onOptionandResultin const contexts for trivial conversions. Note that this does not add any new implementations, it only constifies the existing ones.Simple example:
Public API
Constifies the following impls
Steps / History
impl const Trait for Tyand[const](conditionally const) syntax (const_trait_impl) #67792 and Tracking Issue fortry_trait_v2, A new design for the?desugaring (RFC#3058) #84277Unresolved Questions