Merge rust-lang#91

91: Implement exp2 and exp2f r=japaric a=porglezomp

Closes rust-lang#15
Closes rust-lang#16

Co-authored-by: C Jones <[email protected]>

Author: bors[bot]

src/lib.rs

@@ -70,7 +70,6 @@ pub trait F32Ext: private::Sealed {
 
     fn exp(self) -> Self;
 
-    #[cfg(todo)]
     fn exp2(self) -> Self;
 
     fn ln(self) -> Self;
@@ -214,7 +213,6 @@ impl F32Ext for f32 {
         expf(self)
     }
 
-    #[cfg(todo)]
     #[inline]
     fn exp2(self) -> Self {
         exp2f(self)
@@ -387,7 +385,6 @@ pub trait F64Ext: private::Sealed {
 
     fn exp(self) -> Self;
 
-    #[cfg(todo)]
     fn exp2(self) -> Self;
 
     fn ln(self) -> Self;
@@ -531,7 +528,6 @@ impl F64Ext for f64 {
         exp(self)
     }
 
-    #[cfg(todo)]
     #[inline]
     fn exp2(self) -> Self {
         exp2(self)