Add some f32 and f64 inherent methods in libcore

… previously in the unstable core::num::Float trait.

Per rust-lang#32110 (comment),
the `abs`, `signum`, and `powi` methods are *not* included for now
since they rely on LLVM intrinsics and we haven’t determined yet whether
those instrinsics lower to calls to libm functions on any platform.

Author: SimonSapin

src/liballoc/vec.rs

@@ -74,6 +74,7 @@ use core::iter::{FromIterator, FusedIterator, TrustedLen};
 use core::marker::PhantomData;
 use core::mem;
 #[cfg(not(test))]
+#[cfg(stage0)]
 use core::num::Float;
 use core::ops::Bound::{Excluded, Included, Unbounded};
 use core::ops::{Index, IndexMut, RangeBounds};

src/libcore/lib.rs

@@ -72,6 +72,7 @@
 #![feature(cfg_target_has_atomic)]
 #![feature(concat_idents)]
 #![feature(const_fn)]
+#![feature(core_float)]
 #![feature(custom_attribute)]
 #![feature(doc_cfg)]
 #![feature(doc_spotlight)]

src/libcore/num/f32.rs

@@ -20,6 +20,7 @@
 use intrinsics;
 use mem;
 use num::Float;
+#[cfg(not(stage0))] use num::FpCategory;
 use num::FpCategory as Fp;
 
 /// The radix or base of the internal representation of `f32`.
@@ -292,3 +293,286 @@ impl Float for f32 {
         unsafe { mem::transmute(v) }
     }
 }
+
+// FIXME: remove (inline) this macro and the Float trait
+// when updating to a bootstrap compiler that has the new lang items.
+#[cfg_attr(stage0, macro_export)]
+#[unstable(feature = "core_float", issue = "32110")]
+macro_rules! f32_core_methods { () => {
+    /// Returns `true` if this value is `NaN` and false otherwise.
+    ///
+    /// ```
+    /// use std::f32;
+    ///
+    /// let nan = f32::NAN;
+    /// let f = 7.0_f32;
+    ///
+    /// assert!(nan.is_nan());
+    /// assert!(!f.is_nan());
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn is_nan(self) -> bool { Float::is_nan(self) }
+
+    /// Returns `true` if this value is positive infinity or negative infinity and
+    /// false otherwise.
+    ///
+    /// ```
+    /// use std::f32;
+    ///
+    /// let f = 7.0f32;
+    /// let inf = f32::INFINITY;
+    /// let neg_inf = f32::NEG_INFINITY;
+    /// let nan = f32::NAN;
+    ///
+    /// assert!(!f.is_infinite());
+    /// assert!(!nan.is_infinite());
+    ///
+    /// assert!(inf.is_infinite());
+    /// assert!(neg_inf.is_infinite());
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn is_infinite(self) -> bool { Float::is_infinite(self) }
+
+    /// Returns `true` if this number is neither infinite nor `NaN`.
+    ///
+    /// ```
+    /// use std::f32;
+    ///
+    /// let f = 7.0f32;
+    /// let inf = f32::INFINITY;
+    /// let neg_inf = f32::NEG_INFINITY;
+    /// let nan = f32::NAN;
+    ///
+    /// assert!(f.is_finite());
+    ///
+    /// assert!(!nan.is_finite());
+    /// assert!(!inf.is_finite());
+    /// assert!(!neg_inf.is_finite());
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn is_finite(self) -> bool { Float::is_finite(self) }
+
+    /// Returns `true` if the number is neither zero, infinite,
+    /// [subnormal][subnormal], or `NaN`.
+    ///
+    /// ```
+    /// use std::f32;
+    ///
+    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
+    /// let max = f32::MAX;
+    /// let lower_than_min = 1.0e-40_f32;
+    /// let zero = 0.0_f32;
+    ///
+    /// assert!(min.is_normal());
+    /// assert!(max.is_normal());
+    ///
+    /// assert!(!zero.is_normal());
+    /// assert!(!f32::NAN.is_normal());
+    /// assert!(!f32::INFINITY.is_normal());
+    /// // Values between `0` and `min` are Subnormal.
+    /// assert!(!lower_than_min.is_normal());
+    /// ```
+    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn is_normal(self) -> bool { Float::is_normal(self) }
+
+    /// Returns the floating point category of the number. If only one property
+    /// is going to be tested, it is generally faster to use the specific
+    /// predicate instead.
+    ///
+    /// ```
+    /// use std::num::FpCategory;
+    /// use std::f32;
+    ///
+    /// let num = 12.4_f32;
+    /// let inf = f32::INFINITY;
+    ///
+    /// assert_eq!(num.classify(), FpCategory::Normal);
+    /// assert_eq!(inf.classify(), FpCategory::Infinite);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn classify(self) -> FpCategory { Float::classify(self) }
+
+    /// Returns `true` if and only if `self` has a positive sign, including `+0.0`, `NaN`s with
+    /// positive sign bit and positive infinity.
+    ///
+    /// ```
+    /// let f = 7.0_f32;
+    /// let g = -7.0_f32;
+    ///
+    /// assert!(f.is_sign_positive());
+    /// assert!(!g.is_sign_positive());
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn is_sign_positive(self) -> bool { Float::is_sign_positive(self) }
+
+    /// Returns `true` if and only if `self` has a negative sign, including `-0.0`, `NaN`s with
+    /// negative sign bit and negative infinity.
+    ///
+    /// ```
+    /// let f = 7.0f32;
+    /// let g = -7.0f32;
+    ///
+    /// assert!(!f.is_sign_negative());
+    /// assert!(g.is_sign_negative());
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn is_sign_negative(self) -> bool { Float::is_sign_negative(self) }
+
+    /// Takes the reciprocal (inverse) of a number, `1/x`.
+    ///
+    /// ```
+    /// use std::f32;
+    ///
+    /// let x = 2.0_f32;
+    /// let abs_difference = (x.recip() - (1.0/x)).abs();
+    ///
+    /// assert!(abs_difference <= f32::EPSILON);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn recip(self) -> f32 { Float::recip(self) }
+
+    /// Converts radians to degrees.
+    ///
+    /// ```
+    /// use std::f32::{self, consts};
+    ///
+    /// let angle = consts::PI;
+    ///
+    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
+    ///
+    /// assert!(abs_difference <= f32::EPSILON);
+    /// ```
+    #[stable(feature = "f32_deg_rad_conversions", since="1.7.0")]
+    #[inline]
+    pub fn to_degrees(self) -> f32 { Float::to_degrees(self) }
+
+    /// Converts degrees to radians.
+    ///
+    /// ```
+    /// use std::f32::{self, consts};
+    ///
+    /// let angle = 180.0f32;
+    ///
+    /// let abs_difference = (angle.to_radians() - consts::PI).abs();
+    ///
+    /// assert!(abs_difference <= f32::EPSILON);
+    /// ```
+    #[stable(feature = "f32_deg_rad_conversions", since="1.7.0")]
+    #[inline]
+    pub fn to_radians(self) -> f32 { Float::to_radians(self) }
+
+    /// Returns the maximum of the two numbers.
+    ///
+    /// ```
+    /// let x = 1.0f32;
+    /// let y = 2.0f32;
+    ///
+    /// assert_eq!(x.max(y), y);
+    /// ```
+    ///
+    /// If one of the arguments is NaN, then the other argument is returned.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn max(self, other: f32) -> f32 {
+        Float::max(self, other)
+    }
+
+    /// Returns the minimum of the two numbers.
+    ///
+    /// ```
+    /// let x = 1.0f32;
+    /// let y = 2.0f32;
+    ///
+    /// assert_eq!(x.min(y), x);
+    /// ```
+    ///
+    /// If one of the arguments is NaN, then the other argument is returned.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
+    pub fn min(self, other: f32) -> f32 {
+        Float::min(self, other)
+    }
+
+    /// Raw transmutation to `u32`.
+    ///
+    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
+    ///
+    /// See `from_bits` for some discussion of the portability of this operation
+    /// (there are almost no issues).
+    ///
+    /// Note that this function is distinct from `as` casting, which attempts to
+    /// preserve the *numeric* value, and not the bitwise value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
+    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
+    ///
+    /// ```
+    #[stable(feature = "float_bits_conv", since = "1.20.0")]
+    #[inline]
+    pub fn to_bits(self) -> u32 {
+        Float::to_bits(self)
+    }
+
+    /// Raw transmutation from `u32`.
+    ///
+    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
+    /// It turns out this is incredibly portable, for two reasons:
+    ///
+    /// * Floats and Ints have the same endianness on all supported platforms.
+    /// * IEEE-754 very precisely specifies the bit layout of floats.
+    ///
+    /// However there is one caveat: prior to the 2008 version of IEEE-754, how
+    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
+    /// (notably x86 and ARM) picked the interpretation that was ultimately
+    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
+    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
+    ///
+    /// Rather than trying to preserve signaling-ness cross-platform, this
+    /// implementation favours preserving the exact bits. This means that
+    /// any payloads encoded in NaNs will be preserved even if the result of
+    /// this method is sent over the network from an x86 machine to a MIPS one.
+    ///
+    /// If the results of this method are only manipulated by the same
+    /// architecture that produced them, then there is no portability concern.
+    ///
+    /// If the input isn't NaN, then there is no portability concern.
+    ///
+    /// If you don't care about signalingness (very likely), then there is no
+    /// portability concern.
+    ///
+    /// Note that this function is distinct from `as` casting, which attempts to
+    /// preserve the *numeric* value, and not the bitwise value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::f32;
+    /// let v = f32::from_bits(0x41480000);
+    /// let difference = (v - 12.5).abs();
+    /// assert!(difference <= 1e-5);
+    /// ```
+    #[stable(feature = "float_bits_conv", since = "1.20.0")]
+    #[inline]
+    pub fn from_bits(v: u32) -> Self {
+        Float::from_bits(v)
+    }
+}}
+
+#[lang = "f32"]
+#[cfg(not(test))]
+#[cfg(not(stage0))]
+impl f32 {
+    f32_core_methods!();
+}