Tracking Issue for Duration::from_nanos_u128

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.

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

Add unstable attribute

Add from_nanos_u128 to Duration for handling large time spans

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)

Add from_nanos_u128 to Duration for handling large time spans

@omanirudh

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)

Rollup merge of rust-lang#145969 - actuallylost:duration-from-nanos-1…

Unrolled build for #145969

Rollup merge of rust-lang#145969 - actuallylost:duration-from-nanos-1…

Rollup merge of rust-lang#148587 - RalfJung:duration_from_nanos_u128,…

Auto merge of #148587 - RalfJung:duration_from_nanos_u128, r=Mark-Sim…

Auto merge of rust-lang#148587 - RalfJung:duration_from_nanos_u128, r…

Auto merge of #148587 - RalfJung:duration_from_nanos_u128, r=Mark-Sim…

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Tracking Issue for `Duration::from_nanos_u128` #139201

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Tracking Issue for Duration::from_nanos_u128 #139201

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clarfonthey commented on May 31, 2025

tgross35 commented on Aug 27, 2025

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Tracking Issue for `Duration::from_nanos_u128` #139201