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core: Implement feature float_exact_integer_constants
Implement accepted ACP for `MAX_EXACT_INTEGER` and `MIN_EXACT_INTEGER` on `f16`, `f32`, `f64`, and `f128` Add tests to `coretests/tests/floats/mod.rs` Disable doc tests for i586 since float<->int casts return incorrect results
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‎library/core/src/num/f128.rs‎

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@@ -275,6 +275,70 @@ impl f128 {
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#[unstable(feature = "f128", issue = "116909")]
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pub const NEG_INFINITY: f128 = -1.0_f128 / 0.0_f128;
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/// Maximum integer that can be represented exactly in an [`f128`] value,
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/// with no other integer converting to the same floating point value.
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///
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/// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
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/// there is a "one-to-one" mapping between [`i128`] and [`f128`] values.
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/// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f128`] and back to
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/// [`i128`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f128`] value
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/// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
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/// "one-to-one" mapping.
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///
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/// [`MAX_EXACT_INTEGER`]: f128::MAX_EXACT_INTEGER
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/// [`MIN_EXACT_INTEGER`]: f128::MIN_EXACT_INTEGER
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/// ```
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/// #![feature(f128)]
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/// #![feature(float_exact_integer_constants)]
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/// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
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/// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
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/// # #[cfg(target_has_reliable_f128)] {
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/// let max_exact_int = f128::MAX_EXACT_INTEGER;
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/// assert_eq!(max_exact_int, max_exact_int as f128 as i128);
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/// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f128 as i128);
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/// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f128 as i128);
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///
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/// // Beyond `f128::MAX_EXACT_INTEGER`, multiple integers can map to one float value
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/// assert_eq!((max_exact_int + 1) as f128, (max_exact_int + 2) as f128);
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/// # }}
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/// ```
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// #[unstable(feature = "f128", issue = "116909")]
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#[unstable(feature = "float_exact_integer_constants", issue = "152466")]
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pub const MAX_EXACT_INTEGER: i128 = (1 << Self::MANTISSA_DIGITS) - 1;
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/// Minimum integer that can be represented exactly in an [`f128`] value,
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/// with no other integer converting to the same floating point value.
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///
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/// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
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/// there is a "one-to-one" mapping between [`i128`] and [`f128`] values.
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/// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f128`] and back to
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/// [`i128`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f128`] value
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/// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
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/// "one-to-one" mapping.
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///
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/// This constant is equivalent to `-MAX_EXACT_INTEGER`.
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///
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/// [`MAX_EXACT_INTEGER`]: f128::MAX_EXACT_INTEGER
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/// [`MIN_EXACT_INTEGER`]: f128::MIN_EXACT_INTEGER
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/// ```
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/// #![feature(f128)]
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/// #![feature(float_exact_integer_constants)]
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/// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
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/// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
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/// # #[cfg(target_has_reliable_f128)] {
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/// let min_exact_int = f128::MIN_EXACT_INTEGER;
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/// assert_eq!(min_exact_int, min_exact_int as f128 as i128);
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/// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f128 as i128);
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/// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f128 as i128);
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///
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/// // Below `f128::MIN_EXACT_INTEGER`, multiple integers can map to one float value
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/// assert_eq!((min_exact_int - 1) as f128, (min_exact_int - 2) as f128);
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/// # }}
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/// ```
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// #[unstable(feature = "f128", issue = "116909")]
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#[unstable(feature = "float_exact_integer_constants", issue = "152466")]
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pub const MIN_EXACT_INTEGER: i128 = -Self::MAX_EXACT_INTEGER;
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/// Sign bit
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pub(crate) const SIGN_MASK: u128 = 0x8000_0000_0000_0000_0000_0000_0000_0000;
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‎library/core/src/num/f16.rs‎

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@@ -269,6 +269,70 @@ impl f16 {
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#[unstable(feature = "f16", issue = "116909")]
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pub const NEG_INFINITY: f16 = -1.0_f16 / 0.0_f16;
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/// Maximum integer that can be represented exactly in an [`f16`] value,
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/// with no other integer converting to the same floating point value.
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///
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/// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
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/// there is a "one-to-one" mapping between [`i16`] and [`f16`] values.
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/// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f16`] and back to
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/// [`i16`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f16`] value
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/// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
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/// "one-to-one" mapping.
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///
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/// [`MAX_EXACT_INTEGER`]: f16::MAX_EXACT_INTEGER
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/// [`MIN_EXACT_INTEGER`]: f16::MIN_EXACT_INTEGER
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/// ```
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/// #![feature(f16)]
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/// #![feature(float_exact_integer_constants)]
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/// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
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/// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
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/// # #[cfg(target_has_reliable_f16)] {
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/// let max_exact_int = f16::MAX_EXACT_INTEGER;
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/// assert_eq!(max_exact_int, max_exact_int as f16 as i16);
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/// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f16 as i16);
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/// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f16 as i16);
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///
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/// // Beyond `f16::MAX_EXACT_INTEGER`, multiple integers can map to one float value
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/// assert_eq!((max_exact_int + 1) as f16, (max_exact_int + 2) as f16);
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/// # }}
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/// ```
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// #[unstable(feature = "f16", issue = "116909")]
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#[unstable(feature = "float_exact_integer_constants", issue = "152466")]
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pub const MAX_EXACT_INTEGER: i16 = (1 << Self::MANTISSA_DIGITS) - 1;
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/// Minimum integer that can be represented exactly in an [`f16`] value,
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/// with no other integer converting to the same floating point value.
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///
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/// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
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/// there is a "one-to-one" mapping between [`i16`] and [`f16`] values.
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/// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f16`] and back to
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/// [`i16`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f16`] value
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/// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
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/// "one-to-one" mapping.
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///
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/// This constant is equivalent to `-MAX_EXACT_INTEGER`.
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///
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/// [`MAX_EXACT_INTEGER`]: f16::MAX_EXACT_INTEGER
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/// [`MIN_EXACT_INTEGER`]: f16::MIN_EXACT_INTEGER
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/// ```
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/// #![feature(f16)]
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/// #![feature(float_exact_integer_constants)]
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/// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
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/// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
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/// # #[cfg(target_has_reliable_f16)] {
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/// let min_exact_int = f16::MIN_EXACT_INTEGER;
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/// assert_eq!(min_exact_int, min_exact_int as f16 as i16);
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/// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f16 as i16);
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/// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f16 as i16);
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///
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/// // Below `f16::MIN_EXACT_INTEGER`, multiple integers can map to one float value
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/// assert_eq!((min_exact_int - 1) as f16, (min_exact_int - 2) as f16);
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/// # }}
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/// ```
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// #[unstable(feature = "f16", issue = "116909")]
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#[unstable(feature = "float_exact_integer_constants", issue = "152466")]
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pub const MIN_EXACT_INTEGER: i16 = -Self::MAX_EXACT_INTEGER;
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/// Sign bit
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pub(crate) const SIGN_MASK: u16 = 0x8000;
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‎library/core/src/num/f32.rs‎

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@@ -513,6 +513,64 @@ impl f32 {
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#[stable(feature = "assoc_int_consts", since = "1.43.0")]
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pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
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/// Maximum integer that can be represented exactly in an [`f32`] value,
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/// with no other integer converting to the same floating point value.
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///
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/// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
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/// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
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/// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
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/// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
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/// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
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/// "one-to-one" mapping.
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///
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/// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
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/// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
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/// ```
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/// #![feature(float_exact_integer_constants)]
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/// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
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/// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
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/// let max_exact_int = f32::MAX_EXACT_INTEGER;
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/// assert_eq!(max_exact_int, max_exact_int as f32 as i32);
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/// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f32 as i32);
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/// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f32 as i32);
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///
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/// // Beyond `f32::MAX_EXACT_INTEGER`, multiple integers can map to one float value
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/// assert_eq!((max_exact_int + 1) as f32, (max_exact_int + 2) as f32);
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/// # }
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/// ```
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#[unstable(feature = "float_exact_integer_constants", issue = "152466")]
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pub const MAX_EXACT_INTEGER: i32 = (1 << Self::MANTISSA_DIGITS) - 1;
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/// Minimum integer that can be represented exactly in an [`f32`] value,
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/// with no other integer converting to the same floating point value.
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///
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/// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
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/// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
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/// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
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/// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
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/// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
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/// "one-to-one" mapping.
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///
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/// This constant is equivalent to `-MAX_EXACT_INTEGER`.
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///
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/// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
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/// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
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/// ```
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/// #![feature(float_exact_integer_constants)]
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/// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
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/// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
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/// let min_exact_int = f32::MIN_EXACT_INTEGER;
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/// assert_eq!(min_exact_int, min_exact_int as f32 as i32);
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/// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f32 as i32);
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/// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f32 as i32);
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///
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/// // Below `f32::MIN_EXACT_INTEGER`, multiple integers can map to one float value
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/// assert_eq!((min_exact_int - 1) as f32, (min_exact_int - 2) as f32);
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/// # }
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/// ```
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#[unstable(feature = "float_exact_integer_constants", issue = "152466")]
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pub const MIN_EXACT_INTEGER: i32 = -Self::MAX_EXACT_INTEGER;
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/// Sign bit
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pub(crate) const SIGN_MASK: u32 = 0x8000_0000;
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‎library/core/src/num/f64.rs‎

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@@ -512,6 +512,64 @@ impl f64 {
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#[stable(feature = "assoc_int_consts", since = "1.43.0")]
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pub const NEG_INFINITY: f64 = -1.0_f64 / 0.0_f64;
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/// Maximum integer that can be represented exactly in an [`f64`] value,
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/// with no other integer converting to the same floating point value.
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///
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/// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
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/// there is a "one-to-one" mapping between [`i64`] and [`f64`] values.
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/// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f64`] and back to
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/// [`i64`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f64`] value
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/// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
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/// "one-to-one" mapping.
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///
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/// [`MAX_EXACT_INTEGER`]: f64::MAX_EXACT_INTEGER
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/// [`MIN_EXACT_INTEGER`]: f64::MIN_EXACT_INTEGER
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/// ```
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/// #![feature(float_exact_integer_constants)]
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/// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
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/// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
531+
/// let max_exact_int = f64::MAX_EXACT_INTEGER;
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/// assert_eq!(max_exact_int, max_exact_int as f64 as i64);
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/// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f64 as i64);
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/// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f64 as i64);
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///
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/// // Beyond `f64::MAX_EXACT_INTEGER`, multiple integers can map to one float value
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/// assert_eq!((max_exact_int + 1) as f64, (max_exact_int + 2) as f64);
538+
/// # }
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/// ```
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#[unstable(feature = "float_exact_integer_constants", issue = "152466")]
541+
pub const MAX_EXACT_INTEGER: i64 = (1 << Self::MANTISSA_DIGITS) - 1;
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/// Minimum integer that can be represented exactly in an [`f64`] value,
544+
/// with no other integer converting to the same floating point value.
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///
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/// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
547+
/// there is a "one-to-one" mapping between [`i64`] and [`f64`] values.
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/// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f64`] and back to
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/// [`i64`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f64`] value
550+
/// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
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/// "one-to-one" mapping.
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///
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/// This constant is equivalent to `-MAX_EXACT_INTEGER`.
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///
555+
/// [`MAX_EXACT_INTEGER`]: f64::MAX_EXACT_INTEGER
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/// [`MIN_EXACT_INTEGER`]: f64::MIN_EXACT_INTEGER
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/// ```
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/// #![feature(float_exact_integer_constants)]
559+
/// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
560+
/// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
561+
/// let min_exact_int = f64::MIN_EXACT_INTEGER;
562+
/// assert_eq!(min_exact_int, min_exact_int as f64 as i64);
563+
/// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f64 as i64);
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/// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f64 as i64);
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///
566+
/// // Below `f64::MIN_EXACT_INTEGER`, multiple integers can map to one float value
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/// assert_eq!((min_exact_int - 1) as f64, (min_exact_int - 2) as f64);
568+
/// # }
569+
/// ```
570+
#[unstable(feature = "float_exact_integer_constants", issue = "152466")]
571+
pub const MIN_EXACT_INTEGER: i64 = -Self::MAX_EXACT_INTEGER;
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515573
/// Sign bit
516574
pub(crate) const SIGN_MASK: u64 = 0x8000_0000_0000_0000;
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