diff options
| -rw-r--r-- | library/core/src/time.rs | 33 |
1 files changed, 24 insertions, 9 deletions
diff --git a/library/core/src/time.rs b/library/core/src/time.rs index 46fab01b1bf..6983f10df3f 100644 --- a/library/core/src/time.rs +++ b/library/core/src/time.rs @@ -1288,12 +1288,14 @@ macro_rules! try_from_secs { let rem_msb = nanos_tmp & rem_msb_mask == 0; let add_ns = !(rem_msb || (is_even && is_tie)); - // note that neither `f32`, nor `f64` can represent - // 0.999_999_999_5 exactly, so the nanos part - // never will be equal to NANOS_PER_SEC + // f32 does not have enough presicion to trigger the second branch + // since it can not represent numbers between 0.999_999_940_395 and 1.0. let nanos = nanos + add_ns as u32; - debug_assert!(nanos < NANOS_PER_SEC); - (0, nanos) + if ($mant_bits == 23) || (nanos != NANOS_PER_SEC) { + (0, nanos) + } else { + (1, 0) + } } else if exp < $mant_bits { let secs = u64::from(mant >> ($mant_bits - exp)); let t = <$double_ty>::from((mant << exp) & MANT_MASK); @@ -1309,11 +1311,16 @@ macro_rules! try_from_secs { let rem_msb = nanos_tmp & rem_msb_mask == 0; let add_ns = !(rem_msb || (is_even && is_tie)); - // neither `f32`, nor `f64` can represent x.999_999_999_5 exactly, - // so the nanos part never will be equal to NANOS_PER_SEC + // f32 does not have enough presicion to trigger the second branch. + // For example, it can not represent numbers between 1.999_999_880... + // and 2.0. Bigger values result in even smaller presicion of the + // fractional part. let nanos = nanos + add_ns as u32; - debug_assert!(nanos < NANOS_PER_SEC); - (secs, nanos) + if ($mant_bits == 23) || (nanos != NANOS_PER_SEC) { + (secs, nanos) + } else { + (secs + 1, 0) + } } else if exp < 64 { // the input has no fractional part let secs = u64::from(mant) << (exp - $mant_bits); @@ -1433,6 +1440,14 @@ impl Duration { /// // the conversion uses rounding with tie resolution to even /// let res = Duration::try_from_secs_f64(0.999e-9); /// assert_eq!(res, Ok(Duration::new(0, 1))); + /// let res = Duration::try_from_secs_f64(0.999_999_999_499); + /// assert_eq!(res, Ok(Duration::new(0, 999_999_999))); + /// let res = Duration::try_from_secs_f64(0.999_999_999_501); + /// assert_eq!(res, Ok(Duration::new(1, 0))); + /// let res = Duration::try_from_secs_f64(42.999_999_999_499); + /// assert_eq!(res, Ok(Duration::new(42, 999_999_999))); + /// let res = Duration::try_from_secs_f64(42.999_999_999_501); + /// assert_eq!(res, Ok(Duration::new(43, 0))); /// /// // this float represents exactly 976562.5e-9 /// let val = f64::from_bits(0x3F50_0000_0000_0000); |