"std" feature

Cargo.toml

@@ -12,3 +12,7 @@ version = "0.1.41"
 readme = "README.md"
 
 [dependencies]
+
+[features]
+default = ["std"]
+std = []

ci/rustup.sh

@@ -7,6 +7,9 @@ set -ex
 export TRAVIS_RUST_VERSION
 for TRAVIS_RUST_VERSION in 1.8.0 stable beta nightly; do
     run="rustup run $TRAVIS_RUST_VERSION"
+    if [ "$TRAVIS_RUST_VERSION" = 1.8.0 ]; then
+      $run cargo generate-lockfile
+    fi
     $run cargo build --verbose
     $run $PWD/ci/test_full.sh
 done

ci/test_full.sh

@@ -4,8 +4,14 @@ set -ex
 
 echo Testing num-traits on rustc ${TRAVIS_RUST_VERSION}
 
-# num-integer should build and test everywhere.
+# num-traits should build and test everywhere.
 cargo build --verbose
 cargo test --verbose
 
-# We have no features to test...
+# It should build with minimal features too.
+cargo build --no-default-features
+cargo test --no-default-features
+
+# num-traits with explicit std feature
+cargo build --verbose --no-default-features --features="$feature"
+cargo test --verbose --no-default-features --features="$feature"

src/bounds.rs

@@ -1,7 +1,7 @@
-use std::{usize, u8, u16, u32, u64};
-use std::{isize, i8, i16, i32, i64};
-use std::{f32, f64};
-use std::num::Wrapping;
+use core::{usize, u8, u16, u32, u64};
+use core::{isize, i8, i16, i32, i64};
+use core::{f32, f64};
+use core::num::Wrapping;
 
 /// Numbers which have upper and lower bounds
 pub trait Bounded {

src/cast.rs

@@ -1,8 +1,9 @@
-use std::mem::size_of;
-use std::num::Wrapping;
+use core::mem::size_of;
+use core::num::Wrapping;
 
 use identities::Zero;
 use bounds::Bounded;
+use float::Float;
 
 /// A generic trait for converting a value to a number.
 pub trait ToPrimitive {
@@ -226,8 +227,8 @@ macro_rules! impl_to_primitive_float_to_float {
             // Make sure the value is in range for the cast.
             // NaN and +-inf are cast as they are.
             let n = $slf as f64;
-            let max_value: $DstT = ::std::$DstT::MAX;
-            if !n.is_finite() || (-max_value as f64 <= n && n <= max_value as f64) {
+            let max_value: $DstT = ::core::$DstT::MAX;
+            if !Float::is_finite(n) || (-max_value as f64 <= n && n <= max_value as f64) {
                 Some($slf as $DstT)
             } else {
                 None
@@ -454,8 +455,8 @@ impl<T: NumCast> NumCast for Wrapping<T> {
 
 #[test]
 fn to_primitive_float() {
-    use std::f32;
-    use std::f64;
+    use core::f32;
+    use core::f64;
 
     let f32_toolarge = 1e39f64;
     assert_eq!(f32_toolarge.to_f32(), None);