Move intrinsics-based float methods out of libcore into libstd

Affected methods are `abs`, `signum`, and `powi`.
CC rust-lang#32110 (comment)

Author: SimonSapin

src/libcore/num/f32.rs

@@ -17,7 +17,6 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use intrinsics;
 use mem;
 use num::Float;
 #[cfg(not(stage0))] use num::FpCategory;
@@ -189,27 +188,6 @@ impl Float for f32 {
         }
     }
 
-    /// Computes the absolute value of `self`. Returns `Float::nan()` if the
-    /// number is `Float::nan()`.
-    #[inline]
-    fn abs(self) -> f32 {
-        unsafe { intrinsics::fabsf32(self) }
-    }
-
-    /// Returns a number that represents the sign of `self`.
-    ///
-    /// - `1.0` if the number is positive, `+0.0` or `Float::infinity()`
-    /// - `-1.0` if the number is negative, `-0.0` or `Float::neg_infinity()`
-    /// - `Float::nan()` if the number is `Float::nan()`
-    #[inline]
-    fn signum(self) -> f32 {
-        if self.is_nan() {
-            NAN
-        } else {
-            unsafe { intrinsics::copysignf32(1.0, self) }
-        }
-    }
-
     /// Returns `true` if and only if `self` has a positive sign, including `+0.0`, `NaN`s with
     /// positive sign bit and positive infinity.
     #[inline]
@@ -232,11 +210,6 @@ impl Float for f32 {
         1.0 / self
     }
 
-    #[inline]
-    fn powi(self, n: i32) -> f32 {
-        unsafe { intrinsics::powif32(self, n) }
-    }
-
     /// Converts to degrees, assuming the number is in radians.
     #[inline]
     fn to_degrees(self) -> f32 {

src/libcore/num/f64.rs

@@ -17,7 +17,6 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use intrinsics;
 use mem;
 use num::Float;
 #[cfg(not(stage0))] use num::FpCategory;
@@ -189,27 +188,6 @@ impl Float for f64 {
         }
     }
 
-    /// Computes the absolute value of `self`. Returns `Float::nan()` if the
-    /// number is `Float::nan()`.
-    #[inline]
-    fn abs(self) -> f64 {
-        unsafe { intrinsics::fabsf64(self) }
-    }
-
-    /// Returns a number that represents the sign of `self`.
-    ///
-    /// - `1.0` if the number is positive, `+0.0` or `Float::infinity()`
-    /// - `-1.0` if the number is negative, `-0.0` or `Float::neg_infinity()`
-    /// - `Float::nan()` if the number is `Float::nan()`
-    #[inline]
-    fn signum(self) -> f64 {
-        if self.is_nan() {
-            NAN
-        } else {
-            unsafe { intrinsics::copysignf64(1.0, self) }
-        }
-    }
-
     /// Returns `true` if and only if `self` has a positive sign, including `+0.0`, `NaN`s with
     /// positive sign bit and positive infinity.
     #[inline]
@@ -230,11 +208,6 @@ impl Float for f64 {
         1.0 / self
     }
 
-    #[inline]
-    fn powi(self, n: i32) -> f64 {
-        unsafe { intrinsics::powif64(self, n) }
-    }
-
     /// Converts to degrees, assuming the number is in radians.
     #[inline]
     fn to_degrees(self) -> f64 {

src/libcore/num/mod.rs

@@ -4125,18 +4125,6 @@ pub trait Float: Sized {
     #[stable(feature = "core", since = "1.6.0")]
     fn classify(self) -> FpCategory;
 
-    /// Computes the absolute value of `self`. Returns `Float::nan()` if the
-    /// number is `Float::nan()`.
-    #[stable(feature = "core", since = "1.6.0")]
-    fn abs(self) -> Self;
-    /// Returns a number that represents the sign of `self`.
-    ///
-    /// - `1.0` if the number is positive, `+0.0` or `Float::infinity()`
-    /// - `-1.0` if the number is negative, `-0.0` or `Float::neg_infinity()`
-    /// - `Float::nan()` if the number is `Float::nan()`
-    #[stable(feature = "core", since = "1.6.0")]
-    fn signum(self) -> Self;
-
     /// Returns `true` if `self` is positive, including `+0.0` and
     /// `Float::infinity()`.
     #[stable(feature = "core", since = "1.6.0")]
@@ -4150,12 +4138,6 @@ pub trait Float: Sized {
     #[stable(feature = "core", since = "1.6.0")]
     fn recip(self) -> Self;
 
-    /// Raise a number to an integer power.
-    ///
-    /// Using this function is generally faster than using `powf`
-    #[stable(feature = "core", since = "1.6.0")]
-    fn powi(self, n: i32) -> Self;
-
     /// Convert radians to degrees.
     #[stable(feature = "deg_rad_conversions", since="1.7.0")]
     fn to_degrees(self) -> Self;

src/librustc_typeck/diagnostics.rs

@@ -4526,23 +4526,23 @@ but the type of the numeric value or binding could not be identified.
 The error happens on numeric literals:
 
 ```compile_fail,E0689
-2.0.powi(2);
+2.0.recip();
 ```
 
 and on numeric bindings without an identified concrete type:
 
 ```compile_fail,E0689
 let x = 2.0;
-x.powi(2);  // same error as above
+x.recip();  // same error as above
 ```
 
 Because of this, you must give the numeric literal or binding a type:
 
 ```
-let _ = 2.0_f32.powi(2);
+let _ = 2.0_f32.recip();
 let x: f32 = 2.0;
-let _ = x.powi(2);
-let _ = (2.0 as f32).powi(2);
+let _ = x.recip();
+let _ = (2.0 as f32).recip();
 ```
 "##,
 

src/libstd/f32.rs

@@ -19,6 +19,7 @@
 #![allow(missing_docs)]
 
 #[cfg(not(test))]
+#[cfg(stage0)]
 use core::num::Float;
 #[cfg(not(test))]
 use intrinsics;
@@ -163,7 +164,9 @@ impl f32 {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn abs(self) -> f32 { Float::abs(self) }
+    pub fn abs(self) -> f32 {
+        unsafe { intrinsics::fabsf32(self) }
+    }
 
     /// Returns a number that represents the sign of `self`.
     ///
@@ -183,7 +186,13 @@ impl f32 {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn signum(self) -> f32 { Float::signum(self) }
+    pub fn signum(self) -> f32 {
+        if self.is_nan() {
+            NAN
+        } else {
+            unsafe { intrinsics::copysignf32(1.0, self) }
+        }
+    }
 
     /// Fused multiply-add. Computes `(self * a) + b` with only one rounding
     /// error. This produces a more accurate result with better performance than
@@ -272,7 +281,9 @@ impl f32 {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn powi(self, n: i32) -> f32 { Float::powi(self, n) }
+    pub fn powi(self, n: i32) -> f32 {
+        unsafe { intrinsics::powif32(self, n) }
+    }
 
     /// Raises a number to a floating point power.
     ///

src/libstd/f64.rs

@@ -19,6 +19,7 @@
 #![allow(missing_docs)]
 
 #[cfg(not(test))]
+#[cfg(stage0)]
 use core::num::Float;
 #[cfg(not(test))]
 use intrinsics;
@@ -141,7 +142,9 @@ impl f64 {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn abs(self) -> f64 { Float::abs(self) }
+    pub fn abs(self) -> f64 {
+        unsafe { intrinsics::fabsf64(self) }
+    }
 
     /// Returns a number that represents the sign of `self`.
     ///
@@ -161,7 +164,13 @@ impl f64 {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn signum(self) -> f64 { Float::signum(self) }
+    pub fn signum(self) -> f64 {
+        if self.is_nan() {
+            NAN
+        } else {
+            unsafe { intrinsics::copysignf64(1.0, self) }
+        }
+    }
 
     /// Fused multiply-add. Computes `(self * a) + b` with only one rounding
     /// error. This produces a more accurate result with better performance than
@@ -245,7 +254,9 @@ impl f64 {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn powi(self, n: i32) -> f64 { Float::powi(self, n) }
+    pub fn powi(self, n: i32) -> f64 {
+        unsafe { intrinsics::powif64(self, n) }
+    }
 
     /// Raises a number to a floating point power.
     ///

src/test/ui/macros/macro-backtrace-invalid-internals.rs

@@ -48,13 +48,13 @@ macro_rules! fake_anon_field_expr {
 
 macro_rules! real_method_stmt {
      () => {
-          2.0.powi(2) //~ ERROR can't call method `powi` on ambiguous numeric type `{float}`
+          2.0.recip() //~ ERROR can't call method `recip` on ambiguous numeric type `{float}`
      }
 }
 
 macro_rules! real_method_expr {
      () => {
-          2.0.powi(2) //~ ERROR can't call method `powi` on ambiguous numeric type `{float}`
+          2.0.recip() //~ ERROR can't call method `recip` on ambiguous numeric type `{float}`
      }
 }
 

src/test/ui/macros/macro-backtrace-invalid-internals.stderr

@@ -25,17 +25,17 @@ LL |           (1).0 //~ ERROR doesn't have fields
 LL |     fake_anon_field_stmt!();
    |     ------------------------ in this macro invocation
 
-error[E0689]: can't call method `powi` on ambiguous numeric type `{float}`
+error[E0689]: can't call method `recip` on ambiguous numeric type `{float}`
   --> $DIR/macro-backtrace-invalid-internals.rs:51:15
    |
-LL |           2.0.powi(2) //~ ERROR can't call method `powi` on ambiguous numeric type `{float}`
-   |               ^^^^
+LL |           2.0.recip() //~ ERROR can't call method `recip` on ambiguous numeric type `{float}`
+   |               ^^^^^
 ...
 LL |     real_method_stmt!();
    |     -------------------- in this macro invocation
 help: you must specify a concrete type for this numeric value, like `f32`
    |
-LL |           2.0_f32.powi(2) //~ ERROR can't call method `powi` on ambiguous numeric type `{float}`
+LL |           2.0_f32.recip() //~ ERROR can't call method `recip` on ambiguous numeric type `{float}`
    |           ^^^^^^^
 
 error[E0599]: no method named `fake` found for type `{integer}` in the current scope
@@ -65,17 +65,17 @@ LL |           (1).0 //~ ERROR doesn't have fields
 LL |     let _ = fake_anon_field_expr!();
    |             ----------------------- in this macro invocation
 
-error[E0689]: can't call method `powi` on ambiguous numeric type `{float}`
+error[E0689]: can't call method `recip` on ambiguous numeric type `{float}`
   --> $DIR/macro-backtrace-invalid-internals.rs:57:15
    |
-LL |           2.0.powi(2) //~ ERROR can't call method `powi` on ambiguous numeric type `{float}`
-   |               ^^^^
+LL |           2.0.recip() //~ ERROR can't call method `recip` on ambiguous numeric type `{float}`
+   |               ^^^^^
 ...
 LL |     let _ = real_method_expr!();
    |             ------------------- in this macro invocation
 help: you must specify a concrete type for this numeric value, like `f32`
    |
-LL |           2.0_f32.powi(2) //~ ERROR can't call method `powi` on ambiguous numeric type `{float}`
+LL |           2.0_f32.recip() //~ ERROR can't call method `recip` on ambiguous numeric type `{float}`
    |           ^^^^^^^
 
 error: aborting due to 8 previous errors

src/test/ui/suggestions/method-on-ambiguous-numeric-type.rs

@@ -9,10 +9,10 @@
 // except according to those terms.
 
 fn main() {
-    let x = 2.0.powi(2);
-    //~^ ERROR can't call method `powi` on ambiguous numeric type `{float}`
+    let x = 2.0.recip();
+    //~^ ERROR can't call method `recip` on ambiguous numeric type `{float}`
     let y = 2.0;
-    let x = y.powi(2);
-    //~^ ERROR can't call method `powi` on ambiguous numeric type `{float}`
+    let x = y.recip();
+    //~^ ERROR can't call method `recip` on ambiguous numeric type `{float}`
     println!("{:?}", x);
 }

src/test/ui/suggestions/method-on-ambiguous-numeric-type.stderr

@@ -1,18 +1,18 @@
-error[E0689]: can't call method `powi` on ambiguous numeric type `{float}`
+error[E0689]: can't call method `recip` on ambiguous numeric type `{float}`
   --> $DIR/method-on-ambiguous-numeric-type.rs:12:17
    |
-LL |     let x = 2.0.powi(2);
-   |                 ^^^^
+LL |     let x = 2.0.recip();
+   |                 ^^^^^
 help: you must specify a concrete type for this numeric value, like `f32`
    |
-LL |     let x = 2.0_f32.powi(2);
+LL |     let x = 2.0_f32.recip();
    |             ^^^^^^^
 
-error[E0689]: can't call method `powi` on ambiguous numeric type `{float}`
+error[E0689]: can't call method `recip` on ambiguous numeric type `{float}`
   --> $DIR/method-on-ambiguous-numeric-type.rs:15:15
    |
-LL |     let x = y.powi(2);
-   |               ^^^^
+LL |     let x = y.recip();
+   |               ^^^^^
 help: you must specify a type for this binding, like `f32`
    |
 LL |     let y: f32 = 2.0;