diff --git a/library/core/src/time.rs b/library/core/src/time.rs index f37e47f132d54..d205bc376f125 100644 --- a/library/core/src/time.rs +++ b/library/core/src/time.rs @@ -308,6 +308,42 @@ impl Duration { Duration { secs, nanos: subsec_nanos } } + /// Creates a new `Duration` from the specified number of nanoseconds. + /// + /// # Panics + /// + /// Panics if the given number of nanoseconds is greater than [`Duration::MAX`]. + /// + /// # Examples + /// + /// ``` + /// #![feature(duration_from_nanos_u128)] + /// use std::time::Duration; + /// + /// let nanos = 10_u128.pow(24) + 321; + /// let duration = Duration::from_nanos_u128(nanos); + /// + /// assert_eq!(10_u64.pow(15), duration.as_secs()); + /// assert_eq!(321, duration.subsec_nanos()); + /// ``` + #[unstable(feature = "duration_from_nanos_u128", issue = "139201")] + // This is necessary because of const `try_from`, but can be removed if a trait-free impl is used instead + #[rustc_const_unstable(feature = "duration_from_nanos_u128", issue = "139201")] + #[must_use] + #[inline] + #[track_caller] + pub const fn from_nanos_u128(nanos: u128) -> Duration { + const NANOS_PER_SEC: u128 = self::NANOS_PER_SEC as u128; + let Ok(secs) = u64::try_from(nanos / NANOS_PER_SEC) else { + panic!("overflow in `Duration::from_nanos_u128`"); + }; + let subsec_nanos = (nanos % NANOS_PER_SEC) as u32; + // SAFETY: x % 1_000_000_000 < 1_000_000_000 also, subsec_nanos >= 0 since u128 >=0 and u32 >=0 + let subsec_nanos = unsafe { Nanoseconds::new_unchecked(subsec_nanos) }; + + Duration { secs: secs as u64, nanos: subsec_nanos } + } + /// Creates a new `Duration` from the specified number of weeks. /// /// # Panics diff --git a/library/coretests/tests/lib.rs b/library/coretests/tests/lib.rs index b9b768f29d788..c95643f0c8e33 100644 --- a/library/coretests/tests/lib.rs +++ b/library/coretests/tests/lib.rs @@ -36,6 +36,7 @@ #![feature(drop_guard)] #![feature(duration_constants)] #![feature(duration_constructors)] +#![feature(duration_from_nanos_u128)] #![feature(error_generic_member_access)] #![feature(exact_div)] #![feature(exact_size_is_empty)] diff --git a/library/coretests/tests/time.rs b/library/coretests/tests/time.rs index bb98e59bf5a2b..fb3c50f9bde98 100644 --- a/library/coretests/tests/time.rs +++ b/library/coretests/tests/time.rs @@ -45,6 +45,14 @@ fn from_weeks_overflow() { let _ = Duration::from_weeks(overflow); } +#[test] +#[should_panic] +fn from_nanos_u128_overflow() { + let nanos_per_sec: u128 = 1_000_000_000; + let overflow = (u64::MAX as u128 * nanos_per_sec) + (nanos_per_sec - 1) + 1; + let _ = Duration::from_nanos_u128(overflow); +} + #[test] fn constructor_weeks() { assert_eq!(Duration::from_weeks(1), Duration::from_secs(7 * 24 * 60 * 60)); @@ -81,6 +89,8 @@ fn secs() { assert_eq!(Duration::from_micros(1_000_001).as_secs(), 1); assert_eq!(Duration::from_nanos(999_999_999).as_secs(), 0); assert_eq!(Duration::from_nanos(1_000_000_001).as_secs(), 1); + assert_eq!(Duration::from_nanos_u128(999_999_999).as_secs(), 0); + assert_eq!(Duration::from_nanos_u128(1_000_000_001).as_secs(), 1); } #[test] @@ -95,6 +105,8 @@ fn millis() { assert_eq!(Duration::from_micros(1_001_000).subsec_millis(), 1); assert_eq!(Duration::from_nanos(999_999_999).subsec_millis(), 999); assert_eq!(Duration::from_nanos(1_001_000_000).subsec_millis(), 1); + assert_eq!(Duration::from_nanos_u128(999_999_999).subsec_millis(), 999); + assert_eq!(Duration::from_nanos_u128(1_001_000_001).subsec_millis(), 1); } #[test] @@ -109,6 +121,8 @@ fn micros() { assert_eq!(Duration::from_micros(1_000_001).subsec_micros(), 1); assert_eq!(Duration::from_nanos(999_999_999).subsec_micros(), 999_999); assert_eq!(Duration::from_nanos(1_000_001_000).subsec_micros(), 1); + assert_eq!(Duration::from_nanos_u128(999_999_999).subsec_micros(), 999_999); + assert_eq!(Duration::from_nanos_u128(1_000_001_000).subsec_micros(), 1); } #[test] @@ -123,6 +137,8 @@ fn nanos() { assert_eq!(Duration::from_micros(1_000_001).subsec_nanos(), 1000); assert_eq!(Duration::from_nanos(999_999_999).subsec_nanos(), 999_999_999); assert_eq!(Duration::from_nanos(1_000_000_001).subsec_nanos(), 1); + assert_eq!(Duration::from_nanos_u128(999_999_999).subsec_nanos(), 999_999_999); + assert_eq!(Duration::from_nanos_u128(1_000_000_001).subsec_nanos(), 1); } #[test] @@ -520,6 +536,9 @@ fn duration_const() { const FROM_NANOS: Duration = Duration::from_nanos(1_000_000_000); assert_eq!(FROM_NANOS, Duration::SECOND); + const FROM_NANOS_U128: Duration = Duration::from_nanos_u128(NANOS); + assert_eq!(FROM_NANOS_U128, Duration::SECOND); + const MAX: Duration = Duration::new(u64::MAX, 999_999_999); const CHECKED_ADD: Option = MAX.checked_add(Duration::SECOND);