Tracking Issue for `Duration::from_nanos_u128`

[RalfJung]

Feature gate: #![feature(duration_from_nanos_u128)]

This is a tracking issue for Duration::from_nanos_u128. See the ACP at rust-lang/libs-team#567.

Public API

// std::time

impl Duration {
    /// Creates a new Duration from the specified number of nanoseconds.
    ///
    /// # Panics
    ///
    /// Panics if the given number of nanoseconds overflows the Duration size.
    pub const fn from_nanos_u128(nanos: u128) -> Duration;
}

Steps / History

• Implementation: Add Duration::from_nanos_u128 #145969
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• Is this the best name we can come up with?
• Should we instead try to generalize from_nanos with a sealed trait? That would block this on const traits.

Footnotes

1. https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩

[clarfonthey]

It would be a bit unprecedented and require const traits, but it feels like the most ideal way to do this would be to use a sealed trait to allow calling this method with both u128 and u64. That way, backwards compatibility isn't broken, but we don't need to settle for a weird, unintuitive combination of methods.

I know that this sort of change can break inference, but I know such breakages are allowed as "non-breaking" changes and there probably wouldn't be a massive impact here.

(note: const traits are only required since the method is already stably const)

[tgross35]

Labeling help wanted: there is a PR at #139243, but @omanirudh requested that somebody else take over #139243 (comment). It should be pretty straightforward to get this over the line: for anybody interested, start with that PR as a base and address the review comments that haven't yet been resolved.

(@omanirudh feel free to correct this if you are still interested in continuing)