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Duration::zero() -> Duration::ZERO #78216

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merged 4 commits into from
Nov 12, 2020
Merged

Duration::zero() -> Duration::ZERO #78216

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d72d5f4
Dogfood Duration API in std::time tests
workingjubilee Oct 22, 2020
ef027a1
Duration::zero() -> Duration::ZERO
workingjubilee Oct 22, 2020
af4d178
Fixup tests: Duration::MIN -> ::ZERO
workingjubilee Oct 27, 2020
82f3a23
Remove Duration::MIN entirely
workingjubilee Oct 27, 2020
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40 changes: 12 additions & 28 deletions library/core/src/time.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -108,18 +108,20 @@ impl Duration {
#[unstable(feature = "duration_constants", issue = "57391")]
pub const NANOSECOND: Duration = Duration::from_nanos(1);

/// The minimum duration.
/// A duration of zero time.
///
/// # Examples
///
/// ```
/// #![feature(duration_constants)]
/// #![feature(duration_zero)]
/// use std::time::Duration;
///
/// assert_eq!(Duration::MIN, Duration::new(0, 0));
/// let duration = Duration::ZERO;
/// assert!(duration.is_zero());
/// assert_eq!(duration.as_nanos(), 0);
/// ```
#[unstable(feature = "duration_constants", issue = "57391")]
pub const MIN: Duration = Duration::from_nanos(0);
#[unstable(feature = "duration_zero", issue = "73544")]
pub const ZERO: Duration = Duration::from_nanos(0);

/// The maximum duration.
///
Expand Down Expand Up @@ -166,24 +168,6 @@ impl Duration {
Duration { secs, nanos }
}

/// Creates a new `Duration` that spans no time.
///
/// # Examples
///
/// ```
/// #![feature(duration_zero)]
/// use std::time::Duration;
///
/// let duration = Duration::zero();
/// assert!(duration.is_zero());
/// assert_eq!(duration.as_nanos(), 0);
/// ```
#[unstable(feature = "duration_zero", issue = "73544")]
#[inline]
pub const fn zero() -> Duration {
Duration { secs: 0, nanos: 0 }
}

/// Creates a new `Duration` from the specified number of whole seconds.
///
/// # Examples
Expand Down Expand Up @@ -277,7 +261,7 @@ impl Duration {
/// #![feature(duration_zero)]
/// use std::time::Duration;
///
/// assert!(Duration::zero().is_zero());
/// assert!(Duration::ZERO.is_zero());
/// assert!(Duration::new(0, 0).is_zero());
/// assert!(Duration::from_nanos(0).is_zero());
/// assert!(Duration::from_secs(0).is_zero());
Expand Down Expand Up @@ -536,26 +520,26 @@ impl Duration {
}
}

/// Saturating `Duration` subtraction. Computes `self - other`, returning [`Duration::MIN`]
/// Saturating `Duration` subtraction. Computes `self - other`, returning [`Duration::ZERO`]
/// if the result would be negative or if overflow occurred.
///
/// # Examples
///
/// ```
/// #![feature(duration_saturating_ops)]
/// #![feature(duration_constants)]
/// #![feature(duration_zero)]
/// use std::time::Duration;
///
/// assert_eq!(Duration::new(0, 1).saturating_sub(Duration::new(0, 0)), Duration::new(0, 1));
/// assert_eq!(Duration::new(0, 0).saturating_sub(Duration::new(0, 1)), Duration::MIN);
/// assert_eq!(Duration::new(0, 0).saturating_sub(Duration::new(0, 1)), Duration::ZERO);
/// ```
#[unstable(feature = "duration_saturating_ops", issue = "76416")]
#[inline]
#[rustc_const_unstable(feature = "duration_consts_2", issue = "72440")]
pub const fn saturating_sub(self, rhs: Duration) -> Duration {
match self.checked_sub(rhs) {
Some(res) => res,
None => Duration::MIN,
None => Duration::ZERO,
}
}

Expand Down
97 changes: 46 additions & 51 deletions library/core/tests/time.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -108,24 +108,24 @@ fn sub() {

#[test]
fn checked_sub() {
let zero = Duration::new(0, 0);
let one_nano = Duration::new(0, 1);
let one_sec = Duration::new(1, 0);
assert_eq!(one_nano.checked_sub(zero), Some(Duration::new(0, 1)));
assert_eq!(one_sec.checked_sub(one_nano), Some(Duration::new(0, 999_999_999)));
assert_eq!(zero.checked_sub(one_nano), None);
assert_eq!(zero.checked_sub(one_sec), None);
assert_eq!(Duration::NANOSECOND.checked_sub(Duration::ZERO), Some(Duration::NANOSECOND));
assert_eq!(
Duration::SECOND.checked_sub(Duration::NANOSECOND),
Some(Duration::new(0, 999_999_999))
);
assert_eq!(Duration::ZERO.checked_sub(Duration::NANOSECOND), None);
assert_eq!(Duration::ZERO.checked_sub(Duration::SECOND), None);
}

#[test]
fn saturating_sub() {
let zero = Duration::new(0, 0);
let one_nano = Duration::new(0, 1);
let one_sec = Duration::new(1, 0);
assert_eq!(one_nano.saturating_sub(zero), Duration::new(0, 1));
assert_eq!(one_sec.saturating_sub(one_nano), Duration::new(0, 999_999_999));
assert_eq!(zero.saturating_sub(one_nano), Duration::MIN);
assert_eq!(zero.saturating_sub(one_sec), Duration::MIN);
assert_eq!(Duration::NANOSECOND.saturating_sub(Duration::ZERO), Duration::NANOSECOND);
assert_eq!(
Duration::SECOND.saturating_sub(Duration::NANOSECOND),
Duration::new(0, 999_999_999)
);
assert_eq!(Duration::ZERO.saturating_sub(Duration::NANOSECOND), Duration::ZERO);
assert_eq!(Duration::ZERO.saturating_sub(Duration::SECOND), Duration::ZERO);
}

#[test]
Expand Down Expand Up @@ -337,87 +337,82 @@ fn duration_const() {
const SUB_SEC_NANOS: u32 = DURATION.subsec_nanos();
assert_eq!(SUB_SEC_NANOS, 123_456_789);

const ZERO: Duration = Duration::zero();
assert_eq!(ZERO, Duration::new(0, 0));

const IS_ZERO: bool = ZERO.is_zero();
const IS_ZERO: bool = Duration::ZERO.is_zero();
assert!(IS_ZERO);

const ONE: Duration = Duration::new(1, 0);

const SECONDS: u64 = ONE.as_secs();
const SECONDS: u64 = Duration::SECOND.as_secs();
assert_eq!(SECONDS, 1);

const FROM_SECONDS: Duration = Duration::from_secs(1);
assert_eq!(FROM_SECONDS, ONE);
assert_eq!(FROM_SECONDS, Duration::SECOND);

const SECONDS_F32: f32 = ONE.as_secs_f32();
const SECONDS_F32: f32 = Duration::SECOND.as_secs_f32();
assert_eq!(SECONDS_F32, 1.0);

const FROM_SECONDS_F32: Duration = Duration::from_secs_f32(1.0);
assert_eq!(FROM_SECONDS_F32, ONE);
assert_eq!(FROM_SECONDS_F32, Duration::SECOND);

const SECONDS_F64: f64 = ONE.as_secs_f64();
const SECONDS_F64: f64 = Duration::SECOND.as_secs_f64();
assert_eq!(SECONDS_F64, 1.0);

const FROM_SECONDS_F64: Duration = Duration::from_secs_f64(1.0);
assert_eq!(FROM_SECONDS_F64, ONE);
assert_eq!(FROM_SECONDS_F64, Duration::SECOND);

const MILLIS: u128 = ONE.as_millis();
const MILLIS: u128 = Duration::SECOND.as_millis();
assert_eq!(MILLIS, 1_000);

const FROM_MILLIS: Duration = Duration::from_millis(1_000);
assert_eq!(FROM_MILLIS, ONE);
assert_eq!(FROM_MILLIS, Duration::SECOND);

const MICROS: u128 = ONE.as_micros();
const MICROS: u128 = Duration::SECOND.as_micros();
assert_eq!(MICROS, 1_000_000);

const FROM_MICROS: Duration = Duration::from_micros(1_000_000);
assert_eq!(FROM_MICROS, ONE);
assert_eq!(FROM_MICROS, Duration::SECOND);

const NANOS: u128 = ONE.as_nanos();
const NANOS: u128 = Duration::SECOND.as_nanos();
assert_eq!(NANOS, 1_000_000_000);

const FROM_NANOS: Duration = Duration::from_nanos(1_000_000_000);
assert_eq!(FROM_NANOS, ONE);
assert_eq!(FROM_NANOS, Duration::SECOND);

const MAX: Duration = Duration::new(u64::MAX, 999_999_999);

const CHECKED_ADD: Option<Duration> = MAX.checked_add(ONE);
const CHECKED_ADD: Option<Duration> = MAX.checked_add(Duration::SECOND);
assert_eq!(CHECKED_ADD, None);

const CHECKED_SUB: Option<Duration> = ZERO.checked_sub(ONE);
const CHECKED_SUB: Option<Duration> = Duration::ZERO.checked_sub(Duration::SECOND);
assert_eq!(CHECKED_SUB, None);

const CHECKED_MUL: Option<Duration> = ONE.checked_mul(1);
assert_eq!(CHECKED_MUL, Some(ONE));
const CHECKED_MUL: Option<Duration> = Duration::SECOND.checked_mul(1);
assert_eq!(CHECKED_MUL, Some(Duration::SECOND));

const MUL_F32: Duration = ONE.mul_f32(1.0);
assert_eq!(MUL_F32, ONE);
const MUL_F32: Duration = Duration::SECOND.mul_f32(1.0);
assert_eq!(MUL_F32, Duration::SECOND);

const MUL_F64: Duration = ONE.mul_f64(1.0);
assert_eq!(MUL_F64, ONE);
const MUL_F64: Duration = Duration::SECOND.mul_f64(1.0);
assert_eq!(MUL_F64, Duration::SECOND);

const CHECKED_DIV: Option<Duration> = ONE.checked_div(1);
assert_eq!(CHECKED_DIV, Some(ONE));
const CHECKED_DIV: Option<Duration> = Duration::SECOND.checked_div(1);
assert_eq!(CHECKED_DIV, Some(Duration::SECOND));

const DIV_F32: Duration = ONE.div_f32(1.0);
assert_eq!(DIV_F32, ONE);
const DIV_F32: Duration = Duration::SECOND.div_f32(1.0);
assert_eq!(DIV_F32, Duration::SECOND);

const DIV_F64: Duration = ONE.div_f64(1.0);
assert_eq!(DIV_F64, ONE);
const DIV_F64: Duration = Duration::SECOND.div_f64(1.0);
assert_eq!(DIV_F64, Duration::SECOND);

const DIV_DURATION_F32: f32 = ONE.div_duration_f32(ONE);
const DIV_DURATION_F32: f32 = Duration::SECOND.div_duration_f32(Duration::SECOND);
assert_eq!(DIV_DURATION_F32, 1.0);

const DIV_DURATION_F64: f64 = ONE.div_duration_f64(ONE);
const DIV_DURATION_F64: f64 = Duration::SECOND.div_duration_f64(Duration::SECOND);
assert_eq!(DIV_DURATION_F64, 1.0);

const SATURATING_ADD: Duration = MAX.saturating_add(ONE);
const SATURATING_ADD: Duration = MAX.saturating_add(Duration::SECOND);
assert_eq!(SATURATING_ADD, MAX);

const SATURATING_SUB: Duration = ZERO.saturating_sub(ONE);
assert_eq!(SATURATING_SUB, ZERO);
const SATURATING_SUB: Duration = Duration::ZERO.saturating_sub(Duration::SECOND);
assert_eq!(SATURATING_SUB, Duration::ZERO);

const SATURATING_MUL: Duration = MAX.saturating_mul(2);
assert_eq!(SATURATING_MUL, MAX);
Expand Down
1 change: 1 addition & 0 deletions library/std/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -255,6 +255,7 @@
#![feature(doc_spotlight)]
#![feature(dropck_eyepatch)]
#![feature(duration_constants)]
#![feature(duration_zero)]
#![feature(exact_size_is_empty)]
#![feature(exhaustive_patterns)]
#![feature(extend_one)]
Expand Down
32 changes: 16 additions & 16 deletions library/std/src/time/tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ macro_rules! assert_almost_eq {
let (a, b) = ($a, $b);
if a != b {
let (a, b) = if a > b { (a, b) } else { (b, a) };
assert!(a - Duration::new(0, 1000) <= b, "{:?} is not almost equal to {:?}", a, b);
assert!(a - Duration::from_micros(1) <= b, "{:?} is not almost equal to {:?}", a, b);
}
}};
}
Expand Down Expand Up @@ -34,7 +34,7 @@ fn instant_math() {
assert_almost_eq!(b - dur, a);
assert_almost_eq!(a + dur, b);

let second = Duration::new(1, 0);
let second = Duration::SECOND;
assert_almost_eq!(a - second + second, a);
assert_almost_eq!(a.checked_sub(second).unwrap().checked_add(second).unwrap(), a);

Expand Down Expand Up @@ -65,32 +65,32 @@ fn instant_math_is_associative() {
#[should_panic]
fn instant_duration_since_panic() {
let a = Instant::now();
(a - Duration::new(1, 0)).duration_since(a);
(a - Duration::SECOND).duration_since(a);
}

#[test]
fn instant_checked_duration_since_nopanic() {
let now = Instant::now();
let earlier = now - Duration::new(1, 0);
let later = now + Duration::new(1, 0);
let earlier = now - Duration::SECOND;
let later = now + Duration::SECOND;
assert_eq!(earlier.checked_duration_since(now), None);
assert_eq!(later.checked_duration_since(now), Some(Duration::new(1, 0)));
assert_eq!(now.checked_duration_since(now), Some(Duration::new(0, 0)));
assert_eq!(later.checked_duration_since(now), Some(Duration::SECOND));
assert_eq!(now.checked_duration_since(now), Some(Duration::ZERO));
}

#[test]
fn instant_saturating_duration_since_nopanic() {
let a = Instant::now();
let ret = (a - Duration::new(1, 0)).saturating_duration_since(a);
assert_eq!(ret, Duration::new(0, 0));
let ret = (a - Duration::SECOND).saturating_duration_since(a);
assert_eq!(ret, Duration::ZERO);
}

#[test]
fn system_time_math() {
let a = SystemTime::now();
let b = SystemTime::now();
match b.duration_since(a) {
Ok(dur) if dur == Duration::new(0, 0) => {
Ok(Duration::ZERO) => {
assert_almost_eq!(a, b);
}
Ok(dur) => {
Expand All @@ -106,16 +106,16 @@ fn system_time_math() {
}
}

let second = Duration::new(1, 0);
let second = Duration::SECOND;
assert_almost_eq!(a.duration_since(a - second).unwrap(), second);
assert_almost_eq!(a.duration_since(a + second).unwrap_err().duration(), second);

assert_almost_eq!(a - second + second, a);
assert_almost_eq!(a.checked_sub(second).unwrap().checked_add(second).unwrap(), a);

let one_second_from_epoch = UNIX_EPOCH + Duration::new(1, 0);
let one_second_from_epoch = UNIX_EPOCH + Duration::SECOND;
let one_second_from_epoch2 =
UNIX_EPOCH + Duration::new(0, 500_000_000) + Duration::new(0, 500_000_000);
UNIX_EPOCH + Duration::from_millis(500) + Duration::from_millis(500);
assert_eq!(one_second_from_epoch, one_second_from_epoch2);

// checked_add_duration will not panic on overflow
Expand All @@ -141,12 +141,12 @@ fn system_time_elapsed() {
#[test]
fn since_epoch() {
let ts = SystemTime::now();
let a = ts.duration_since(UNIX_EPOCH + Duration::new(1, 0)).unwrap();
let a = ts.duration_since(UNIX_EPOCH + Duration::SECOND).unwrap();
let b = ts.duration_since(UNIX_EPOCH).unwrap();
assert!(b > a);
assert_eq!(b - a, Duration::new(1, 0));
assert_eq!(b - a, Duration::SECOND);

let thirty_years = Duration::new(1, 0) * 60 * 60 * 24 * 365 * 30;
let thirty_years = Duration::SECOND * 60 * 60 * 24 * 365 * 30;

// Right now for CI this test is run in an emulator, and apparently the
// aarch64 emulator's sense of time is that we're still living in the
Expand Down