Merge the Round trait into the Float trait

Move the rounding functions into the `std::num::Float` trait and then remove `std::num::Round`.

This continues the flattening of the numeric traits tracked in #10387. The aim is to make `std::num` very simple and tied to the built in types, leaving the definition of more complex numeric towers to third-party libraries.

[breaking-change]

5 files changed, 71 insertions, 78 deletions

diff --git a/src/libstd/num/f32.rs b/src/libstd/num/f32.rs
index 7cd6aaa6310..893897e661a 100644
--- a/src/libstd/num/f32.rs
+++ b/src/libstd/num/f32.rs
@@ -239,33 +239,6 @@ impl Signed for f32 {
     fn is_negative(&self) -> bool { *self < 0.0 || (1.0 / *self) == NEG_INFINITY }
 }
 
-impl Round for f32 {
-    /// Round half-way cases toward `NEG_INFINITY`
-    #[inline]
-    fn floor(&self) -> f32 { unsafe{intrinsics::floorf32(*self)} }
-
-    /// Round half-way cases toward `INFINITY`
-    #[inline]
-    fn ceil(&self) -> f32 { unsafe{intrinsics::ceilf32(*self)} }
-
-    /// Round half-way cases away from `0.0`
-    #[inline]
-    fn round(&self) -> f32 { unsafe{intrinsics::roundf32(*self)} }
-
-    /// The integer part of the number (rounds towards `0.0`)
-    #[inline]
-    fn trunc(&self) -> f32 { unsafe{intrinsics::truncf32(*self)} }
-
-    /// The fractional part of the number, satisfying:
-    ///
-    /// ```rust
-    /// let x = 1.65f32;
-    /// assert!(x == x.trunc() + x.fract())
-    /// ```
-    #[inline]
-    fn fract(&self) -> f32 { *self - self.trunc() }
-}
-
 impl Bounded for f32 {
     #[inline]
     fn min_value() -> f32 { 1.17549435e-38 }
@@ -414,6 +387,31 @@ impl Float for f32 {
         (mantissa as u64, exponent, sign)
     }
 
+    /// Round half-way cases toward `NEG_INFINITY`
+    #[inline]
+    fn floor(&self) -> f32 { unsafe{intrinsics::floorf32(*self)} }
+
+    /// Round half-way cases toward `INFINITY`
+    #[inline]
+    fn ceil(&self) -> f32 { unsafe{intrinsics::ceilf32(*self)} }
+
+    /// Round half-way cases away from `0.0`
+    #[inline]
+    fn round(&self) -> f32 { unsafe{intrinsics::roundf32(*self)} }
+
+    /// The integer part of the number (rounds towards `0.0`)
+    #[inline]
+    fn trunc(&self) -> f32 { unsafe{intrinsics::truncf32(*self)} }
+
+    /// The fractional part of the number, satisfying:
+    ///
+    /// ```rust
+    /// let x = 1.65f32;
+    /// assert!(x == x.trunc() + x.fract())
+    /// ```
+    #[inline]
+    fn fract(&self) -> f32 { *self - self.trunc() }
+
     /// Archimedes' constant
     #[inline]
     fn pi() -> f32 { 3.14159265358979323846264338327950288 }
diff --git a/src/libstd/num/f64.rs b/src/libstd/num/f64.rs
index 8b52a6747f4..cf6fadd38aa 100644
--- a/src/libstd/num/f64.rs
+++ b/src/libstd/num/f64.rs
@@ -247,33 +247,6 @@ impl Signed for f64 {
     fn is_negative(&self) -> bool { *self < 0.0 || (1.0 / *self) == NEG_INFINITY }
 }
 
-impl Round for f64 {
-    /// Round half-way cases toward `NEG_INFINITY`
-    #[inline]
-    fn floor(&self) -> f64 { unsafe{intrinsics::floorf64(*self)} }
-
-    /// Round half-way cases toward `INFINITY`
-    #[inline]
-    fn ceil(&self) -> f64 { unsafe{intrinsics::ceilf64(*self)} }
-
-    /// Round half-way cases away from `0.0`
-    #[inline]
-    fn round(&self) -> f64 { unsafe{intrinsics::roundf64(*self)} }
-
-    /// The integer part of the number (rounds towards `0.0`)
-    #[inline]
-    fn trunc(&self) -> f64 { unsafe{intrinsics::truncf64(*self)} }
-
-    /// The fractional part of the number, satisfying:
-    ///
-    /// ```rust
-    /// let x = 1.65f64;
-    /// assert!(x == x.trunc() + x.fract())
-    /// ```
-    #[inline]
-    fn fract(&self) -> f64 { *self - self.trunc() }
-}
-
 impl Bounded for f64 {
     #[inline]
     fn min_value() -> f64 { 2.2250738585072014e-308 }
@@ -420,6 +393,31 @@ impl Float for f64 {
         (mantissa, exponent, sign)
     }
 
+    /// Round half-way cases toward `NEG_INFINITY`
+    #[inline]
+    fn floor(&self) -> f64 { unsafe{intrinsics::floorf64(*self)} }
+
+    /// Round half-way cases toward `INFINITY`
+    #[inline]
+    fn ceil(&self) -> f64 { unsafe{intrinsics::ceilf64(*self)} }
+
+    /// Round half-way cases away from `0.0`
+    #[inline]
+    fn round(&self) -> f64 { unsafe{intrinsics::roundf64(*self)} }
+
+    /// The integer part of the number (rounds towards `0.0`)
+    #[inline]
+    fn trunc(&self) -> f64 { unsafe{intrinsics::truncf64(*self)} }
+
+    /// The fractional part of the number, satisfying:
+    ///
+    /// ```rust
+    /// let x = 1.65f64;
+    /// assert!(x == x.trunc() + x.fract())
+    /// ```
+    #[inline]
+    fn fract(&self) -> f64 { *self - self.trunc() }
+
     /// Archimedes' constant
     #[inline]
     fn pi() -> f64 { 3.14159265358979323846264338327950288 }
diff --git a/src/libstd/num/mod.rs b/src/libstd/num/mod.rs
index 12befed743a..b3e15a97086 100644
--- a/src/libstd/num/mod.rs
+++ b/src/libstd/num/mod.rs
@@ -162,25 +162,6 @@ pub fn abs_sub<T: Signed>(x: T, y: T) -> T {
 /// A trait for values which cannot be negative
 pub trait Unsigned: Num {}
 
-/// A collection of rounding operations.
-pub trait Round {
-    /// Return the largest integer less than or equal to a number.
-    fn floor(&self) -> Self;
-
-    /// Return the smallest integer greater than or equal to a number.
-    fn ceil(&self) -> Self;
-
-    /// Return the nearest integer to a number. Round half-way cases away from
-    /// `0.0`.
-    fn round(&self) -> Self;
-
-    /// Return the integer part of a number.
-    fn trunc(&self) -> Self;
-
-    /// Return the fractional part of a number.
-    fn fract(&self) -> Self;
-}
-
 /// Raises a value to the power of exp, using exponentiation by squaring.
 ///
 /// # Example
@@ -347,7 +328,7 @@ pub enum FPCategory {
 //
 // FIXME(#8888): Several of these functions have a parameter named
 //               `unused_self`. Removing it requires #8888 to be fixed.
-pub trait Float: Signed + Round + Primitive {
+pub trait Float: Signed + Primitive {
     /// Returns the maximum of the two numbers.
     fn max(self, other: Self) -> Self;
     /// Returns the minimum of the two numbers.
@@ -431,6 +412,22 @@ pub trait Float: Signed + Round + Primitive {
     /// Returns the mantissa, exponent and sign as integers, respectively.
     fn integer_decode(&self) -> (u64, i16, i8);
 
+    /// Return the largest integer less than or equal to a number.
+    fn floor(&self) -> Self;
+
+    /// Return the smallest integer greater than or equal to a number.
+    fn ceil(&self) -> Self;
+
+    /// Return the nearest integer to a number. Round half-way cases away from
+    /// `0.0`.
+    fn round(&self) -> Self;
+
+    /// Return the integer part of a number.
+    fn trunc(&self) -> Self;
+
+    /// Return the fractional part of a number.
+    fn fract(&self) -> Self;
+
     /// Archimedes' constant.
     fn pi() -> Self;
 
diff --git a/src/libstd/num/strconv.rs b/src/libstd/num/strconv.rs
index ffcb129d635..73dfbdd088e 100644
--- a/src/libstd/num/strconv.rs
+++ b/src/libstd/num/strconv.rs
@@ -15,7 +15,7 @@ use clone::Clone;
 use container::Container;
 use iter::Iterator;
 use num::{NumCast, Zero, One, cast, Int};
-use num::{Round, Float, FPNaN, FPInfinite, ToPrimitive};
+use num::{Float, FPNaN, FPInfinite, ToPrimitive};
 use num;
 use ops::{Add, Sub, Mul, Div, Rem, Neg};
 use option::{None, Option, Some};
@@ -258,7 +258,7 @@ pub fn int_to_str_bytes_common<T: Int>(num: T, radix: uint, sign: SignFormat, f:
  * - Fails if `radix` > 25 and `exp_format` is `ExpBin` due to conflict
  *   between digit and exponent sign `'p'`.
  */
-pub fn float_to_str_bytes_common<T:NumCast+Zero+One+Eq+Ord+Float+Round+
+pub fn float_to_str_bytes_common<T:NumCast+Zero+One+Eq+Ord+Float+
                                   Div<T,T>+Neg<T>+Rem<T,T>+Mul<T,T>>(
         num: T, radix: uint, negative_zero: bool,
         sign: SignFormat, digits: SignificantDigits, exp_format: ExponentFormat, exp_upper: bool
@@ -491,7 +491,7 @@ pub fn float_to_str_bytes_common<T:NumCast+Zero+One+Eq+Ord+Float+Round+
  * `to_str_bytes_common()`, for details see there.
  */
 #[inline]
-pub fn float_to_str_common<T:NumCast+Zero+One+Eq+Ord+NumStrConv+Float+Round+
+pub fn float_to_str_common<T:NumCast+Zero+One+Eq+Ord+NumStrConv+Float+
                              Div<T,T>+Neg<T>+Rem<T,T>+Mul<T,T>>(
         num: T, radix: uint, negative_zero: bool,
         sign: SignFormat, digits: SignificantDigits, exp_format: ExponentFormat, exp_capital: bool
diff --git a/src/libstd/prelude.rs b/src/libstd/prelude.rs
index a44b23c4249..724c4ca72ad 100644
--- a/src/libstd/prelude.rs
+++ b/src/libstd/prelude.rs
@@ -45,7 +45,7 @@ pub use iter::{FromIterator, Extendable};
 pub use iter::{Iterator, DoubleEndedIterator, RandomAccessIterator, CloneableIterator};
 pub use iter::{OrdIterator, MutableDoubleEndedIterator, ExactSize};
 pub use num::{Num, NumCast, CheckedAdd, CheckedSub, CheckedMul};
-pub use num::{Signed, Unsigned, Round};
+pub use num::{Signed, Unsigned};
 pub use num::{Primitive, Int, Float, ToPrimitive, FromPrimitive};
 pub use path::{GenericPath, Path, PosixPath, WindowsPath};
 pub use ptr::RawPtr;