Automatically detect support for i128/u128

Cargo.toml

@@ -10,9 +10,10 @@ repository = "https://github.com/rust-num/num-traits"
 name = "num-traits"
 version = "0.2.3"
 readme = "README.md"
+build = "build.rs"
 
 [package.metadata.docs.rs]
-all-features = true
+features = ["std"]
 
 [dependencies]
 

README.md

@@ -38,7 +38,9 @@ The `Float` and `Real` traits are only available when `std` is enabled. The
 and `f64` also require `std`, as do implementations of signed and floating-
 point exponents in `Pow`.
 
-Implementations for `i128` and `u128` are only available when `i128` is enabled.
+Implementations for `i128` and `u128` are only available with Rust 1.26 and
+later.  The build script automatically detects this, but you can make it
+mandatory by enabling the `i128` crate feature.
 
 ## Releases
 

build.rs

@@ -0,0 +1,35 @@
+use std::env;
+use std::io::Write;
+use std::process::{Command, Stdio};
+
+fn main() {
+    if probe("fn main() { 0i128; }") {
+        println!("cargo:rustc-cfg=has_i128");
+    } else if env::var_os("CARGO_FEATURE_I128").is_some() {
+        panic!("i128 support was not detected!");
+    }
+}
+
+/// Test if a code snippet can be compiled
+fn probe(code: &str) -> bool {
+    let rustc = env::var_os("RUSTC").unwrap_or_else(|| "rustc".into());
+    let out_dir = env::var_os("OUT_DIR").expect("environment variable OUT_DIR");
+
+    let mut child = Command::new(rustc)
+        .arg("--out-dir")
+        .arg(out_dir)
+        .arg("--emit=obj")
+        .arg("-")
+        .stdin(Stdio::piped())
+        .spawn()
+        .expect("rustc probe");
+
+    child
+        .stdin
+        .as_mut()
+        .expect("rustc stdin")
+        .write_all(code.as_bytes())
+        .expect("write rustc stdin");
+
+    child.wait().expect("rustc probe").success()
+}

src/bounds.rs

@@ -2,7 +2,7 @@ use core::{usize, u8, u16, u32, u64};
 use core::{isize, i8, i16, i32, i64};
 use core::{f32, f64};
 use core::num::Wrapping;
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 use core::{i128, u128};
 
 /// Numbers which have upper and lower bounds
@@ -31,7 +31,7 @@ bounded_impl!(u8,    u8::MIN,    u8::MAX);
 bounded_impl!(u16,   u16::MIN,   u16::MAX);
 bounded_impl!(u32,   u32::MIN,   u32::MAX);
 bounded_impl!(u64,   u64::MIN,   u64::MAX);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 bounded_impl!(u128,  u128::MIN,  u128::MAX);
 
 bounded_impl!(isize, isize::MIN, isize::MAX);
@@ -39,7 +39,7 @@ bounded_impl!(i8,    i8::MIN,    i8::MAX);
 bounded_impl!(i16,   i16::MIN,   i16::MAX);
 bounded_impl!(i32,   i32::MIN,   i32::MAX);
 bounded_impl!(i64,   i64::MIN,   i64::MAX);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 bounded_impl!(i128,  i128::MIN,  i128::MAX);
 
 impl<T: Bounded> Bounded for Wrapping<T> {
@@ -97,7 +97,7 @@ fn wrapping_bounded() {
     test_wrapping_bounded!(usize u8 u16 u32 u64 isize i8 i16 i32 i64);
 }
 
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 #[test]
 fn wrapping_bounded_i128() {
     macro_rules! test_wrapping_bounded {

src/cast.rs

@@ -3,7 +3,7 @@ use core::{u8, u16, u32, u64, usize};
 use core::{f32, f64};
 use core::mem::size_of;
 use core::num::Wrapping;
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 use core::{i128, u128};
 
 use float::FloatCore;
@@ -44,7 +44,7 @@ pub trait ToPrimitive {
     /// The default implementation converts through `to_i64()`.  Types implementing
     /// this trait should override this method if they can represent a greater range.
     #[inline]
-    #[cfg(feature = "i128")]
+    #[cfg(has_i128)]
     fn to_i128(&self) -> Option<i128> {
         self.to_i64().map(From::from)
     }
@@ -84,7 +84,7 @@ pub trait ToPrimitive {
     /// The default implementation converts through `to_u64()`.  Types implementing
     /// this trait should override this method if they can represent a greater range.
     #[inline]
-    #[cfg(feature = "i128")]
+    #[cfg(has_i128)]
     fn to_u128(&self) -> Option<u128> {
         self.to_u64().map(From::from)
     }
@@ -142,7 +142,7 @@ macro_rules! impl_to_primitive_int {
                 fn to_i16 -> i16;
                 fn to_i32 -> i32;
                 fn to_i64 -> i64;
-                #[cfg(feature = "i128")]
+                #[cfg(has_i128)]
                 fn to_i128 -> i128;
             }
 
@@ -152,7 +152,7 @@ macro_rules! impl_to_primitive_int {
                 fn to_u16 -> u16;
                 fn to_u32 -> u32;
                 fn to_u64 -> u64;
-                #[cfg(feature = "i128")]
+                #[cfg(has_i128)]
                 fn to_u128 -> u128;
             }
 
@@ -169,7 +169,7 @@ impl_to_primitive_int!(i8);
 impl_to_primitive_int!(i16);
 impl_to_primitive_int!(i32);
 impl_to_primitive_int!(i64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 impl_to_primitive_int!(i128);
 
 macro_rules! impl_to_primitive_uint_to_int {
@@ -211,7 +211,7 @@ macro_rules! impl_to_primitive_uint {
                 fn to_i16 -> i16;
                 fn to_i32 -> i32;
                 fn to_i64 -> i64;
-                #[cfg(feature = "i128")]
+                #[cfg(has_i128)]
                 fn to_i128 -> i128;
             }
 
@@ -221,7 +221,7 @@ macro_rules! impl_to_primitive_uint {
                 fn to_u16 -> u16;
                 fn to_u32 -> u32;
                 fn to_u64 -> u64;
-                #[cfg(feature = "i128")]
+                #[cfg(has_i128)]
                 fn to_u128 -> u128;
             }
 
@@ -238,7 +238,7 @@ impl_to_primitive_uint!(u8);
 impl_to_primitive_uint!(u16);
 impl_to_primitive_uint!(u32);
 impl_to_primitive_uint!(u64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 impl_to_primitive_uint!(u128);
 
 macro_rules! impl_to_primitive_float_to_float {
@@ -324,7 +324,7 @@ macro_rules! impl_to_primitive_float {
                 fn to_i16 -> i16;
                 fn to_i32 -> i32;
                 fn to_i64 -> i64;
-                #[cfg(feature = "i128")]
+                #[cfg(has_i128)]
                 fn to_i128 -> i128;
             }
 
@@ -334,7 +334,7 @@ macro_rules! impl_to_primitive_float {
                 fn to_u16 -> u16;
                 fn to_u32 -> u32;
                 fn to_u64 -> u64;
-                #[cfg(feature = "i128")]
+                #[cfg(has_i128)]
                 fn to_u128 -> u128;
             }
 
@@ -391,7 +391,7 @@ pub trait FromPrimitive: Sized {
     /// The default implementation converts through `from_i64()`.  Types implementing
     /// this trait should override this method if they can represent a greater range.
     #[inline]
-    #[cfg(feature = "i128")]
+    #[cfg(has_i128)]
     fn from_i128(n: i128) -> Option<Self> {
         n.to_i64().and_then(FromPrimitive::from_i64)
     }
@@ -436,7 +436,7 @@ pub trait FromPrimitive: Sized {
     /// The default implementation converts through `from_u64()`.  Types implementing
     /// this trait should override this method if they can represent a greater range.
     #[inline]
-    #[cfg(feature = "i128")]
+    #[cfg(has_i128)]
     fn from_u128(n: u128) -> Option<Self> {
         n.to_u64().and_then(FromPrimitive::from_u64)
     }
@@ -464,14 +464,14 @@ macro_rules! impl_from_primitive {
             #[inline] fn from_i16(n: i16) -> Option<$T> { n.$to_ty() }
             #[inline] fn from_i32(n: i32) -> Option<$T> { n.$to_ty() }
             #[inline] fn from_i64(n: i64) -> Option<$T> { n.$to_ty() }
-            #[cfg(feature = "i128")]
+            #[cfg(has_i128)]
             #[inline] fn from_i128(n: i128) -> Option<$T> { n.$to_ty() }
 
             #[inline] fn from_u8(n: u8) -> Option<$T> { n.$to_ty() }
             #[inline] fn from_u16(n: u16) -> Option<$T> { n.$to_ty() }
             #[inline] fn from_u32(n: u32) -> Option<$T> { n.$to_ty() }
             #[inline] fn from_u64(n: u64) -> Option<$T> { n.$to_ty() }
-            #[cfg(feature = "i128")]
+            #[cfg(has_i128)]
             #[inline] fn from_u128(n: u128) -> Option<$T> { n.$to_ty() }
 
             #[inline] fn from_f32(n: f32) -> Option<$T> { n.$to_ty() }
@@ -485,14 +485,14 @@ impl_from_primitive!(i8,    to_i8);
 impl_from_primitive!(i16,   to_i16);
 impl_from_primitive!(i32,   to_i32);
 impl_from_primitive!(i64,   to_i64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 impl_from_primitive!(i128,  to_i128);
 impl_from_primitive!(usize, to_usize);
 impl_from_primitive!(u8,    to_u8);
 impl_from_primitive!(u16,   to_u16);
 impl_from_primitive!(u32,   to_u32);
 impl_from_primitive!(u64,   to_u64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 impl_from_primitive!(u128,  to_u128);
 impl_from_primitive!(f32,   to_f32);
 impl_from_primitive!(f64,   to_f64);
@@ -515,7 +515,7 @@ impl<T: ToPrimitive> ToPrimitive for Wrapping<T> {
         fn to_i16 -> i16;
         fn to_i32 -> i32;
         fn to_i64 -> i64;
-        #[cfg(feature = "i128")]
+        #[cfg(has_i128)]
         fn to_i128 -> i128;
 
         fn to_usize -> usize;
@@ -523,7 +523,7 @@ impl<T: ToPrimitive> ToPrimitive for Wrapping<T> {
         fn to_u16 -> u16;
         fn to_u32 -> u32;
         fn to_u64 -> u64;
-        #[cfg(feature = "i128")]
+        #[cfg(has_i128)]
         fn to_u128 -> u128;
 
         fn to_f32 -> f32;
@@ -548,7 +548,7 @@ impl<T: FromPrimitive> FromPrimitive for Wrapping<T> {
         fn from_i16(i16);
         fn from_i32(i32);
         fn from_i64(i64);
-        #[cfg(feature = "i128")]
+        #[cfg(has_i128)]
         fn from_i128(i128);
 
         fn from_usize(usize);
@@ -556,7 +556,7 @@ impl<T: FromPrimitive> FromPrimitive for Wrapping<T> {
         fn from_u16(u16);
         fn from_u32(u32);
         fn from_u64(u64);
-        #[cfg(feature = "i128")]
+        #[cfg(has_i128)]
         fn from_u128(u128);
 
         fn from_f32(f32);
@@ -605,14 +605,14 @@ impl_num_cast!(u8,    to_u8);
 impl_num_cast!(u16,   to_u16);
 impl_num_cast!(u32,   to_u32);
 impl_num_cast!(u64,   to_u64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 impl_num_cast!(u128,  to_u128);
 impl_num_cast!(usize, to_usize);
 impl_num_cast!(i8,    to_i8);
 impl_num_cast!(i16,   to_i16);
 impl_num_cast!(i32,   to_i32);
 impl_num_cast!(i64,   to_i64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 impl_num_cast!(i128,  to_i128);
 impl_num_cast!(isize, to_isize);
 impl_num_cast!(f32,   to_f32);
@@ -680,9 +680,9 @@ macro_rules! impl_as_primitive {
     ($T: ty => { $( $U: ty ),* } ) => {
         impl_as_primitive!(@ $T => { $( $U ),* });
         impl_as_primitive!(@ $T => { u8, u16, u32, u64, usize });
-        impl_as_primitive!(@ $T => #[cfg(feature = "i128")] impl u128);
+        impl_as_primitive!(@ $T => #[cfg(has_i128)] impl u128);
         impl_as_primitive!(@ $T => { i8, i16, i32, i64, isize });
-        impl_as_primitive!(@ $T => #[cfg(feature = "i128")] impl i128);
+        impl_as_primitive!(@ $T => #[cfg(has_i128)] impl i128);
     };
 }
 
@@ -694,9 +694,9 @@ impl_as_primitive!(u32 => { f32, f64 });
 impl_as_primitive!(i32 => { f32, f64 });
 impl_as_primitive!(u64 => { f32, f64 });
 impl_as_primitive!(i64 => { f32, f64 });
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 impl_as_primitive!(u128 => { f32, f64 });
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 impl_as_primitive!(i128 => { f32, f64 });
 impl_as_primitive!(usize => { f32, f64 });
 impl_as_primitive!(isize => { f32, f64 });

src/identities.rs

@@ -41,7 +41,7 @@ zero_impl!(u8,    0);
 zero_impl!(u16,   0);
 zero_impl!(u32,   0);
 zero_impl!(u64,   0);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 zero_impl!(u128,  0);
 
 zero_impl!(isize, 0);
@@ -49,7 +49,7 @@ zero_impl!(i8,    0);
 zero_impl!(i16,   0);
 zero_impl!(i32,   0);
 zero_impl!(i64,   0);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 zero_impl!(i128,  0);
 
 zero_impl!(f32, 0.0);
@@ -109,7 +109,7 @@ one_impl!(u8,    1);
 one_impl!(u16,   1);
 one_impl!(u32,   1);
 one_impl!(u64,   1);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 one_impl!(u128,   1);
 
 one_impl!(isize, 1);
@@ -117,7 +117,7 @@ one_impl!(i8,    1);
 one_impl!(i16,   1);
 one_impl!(i32,   1);
 one_impl!(i64,   1);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 one_impl!(i128,   1);
 
 one_impl!(f32, 1.0);

src/int.rs

@@ -368,13 +368,13 @@ prim_int_impl!(u8,    i8,    u8);
 prim_int_impl!(u16,   i16,   u16);
 prim_int_impl!(u32,   i32,   u32);
 prim_int_impl!(u64,   i64,   u64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 prim_int_impl!(u128,  i128,  u128);
 prim_int_impl!(usize, isize, usize);
 prim_int_impl!(i8,    i8,    u8);
 prim_int_impl!(i16,   i16,   u16);
 prim_int_impl!(i32,   i32,   u32);
 prim_int_impl!(i64,   i64,   u64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 prim_int_impl!(i128,  i128,  u128);
 prim_int_impl!(isize, isize, usize);

src/lib.rs

@@ -160,7 +160,7 @@ macro_rules! int_trait_impl {
     )*)
 }
 int_trait_impl!(Num for usize u8 u16 u32 u64 isize i8 i16 i32 i64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 int_trait_impl!(Num for u128 i128);
 
 impl<T: Num> Num for Wrapping<T>

src/ops/checked.rs

@@ -24,7 +24,7 @@ checked_impl!(CheckedAdd, checked_add, u16);
 checked_impl!(CheckedAdd, checked_add, u32);
 checked_impl!(CheckedAdd, checked_add, u64);
 checked_impl!(CheckedAdd, checked_add, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedAdd, checked_add, u128);
 
 checked_impl!(CheckedAdd, checked_add, i8);
@@ -32,7 +32,7 @@ checked_impl!(CheckedAdd, checked_add, i16);
 checked_impl!(CheckedAdd, checked_add, i32);
 checked_impl!(CheckedAdd, checked_add, i64);
 checked_impl!(CheckedAdd, checked_add, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedAdd, checked_add, i128);
 
 /// Performs subtraction that returns `None` instead of wrapping around on underflow.
@@ -47,7 +47,7 @@ checked_impl!(CheckedSub, checked_sub, u16);
 checked_impl!(CheckedSub, checked_sub, u32);
 checked_impl!(CheckedSub, checked_sub, u64);
 checked_impl!(CheckedSub, checked_sub, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedSub, checked_sub, u128);
 
 checked_impl!(CheckedSub, checked_sub, i8);
@@ -55,7 +55,7 @@ checked_impl!(CheckedSub, checked_sub, i16);
 checked_impl!(CheckedSub, checked_sub, i32);
 checked_impl!(CheckedSub, checked_sub, i64);
 checked_impl!(CheckedSub, checked_sub, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedSub, checked_sub, i128);
 
 /// Performs multiplication that returns `None` instead of wrapping around on underflow or
@@ -71,7 +71,7 @@ checked_impl!(CheckedMul, checked_mul, u16);
 checked_impl!(CheckedMul, checked_mul, u32);
 checked_impl!(CheckedMul, checked_mul, u64);
 checked_impl!(CheckedMul, checked_mul, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedMul, checked_mul, u128);
 
 checked_impl!(CheckedMul, checked_mul, i8);
@@ -79,7 +79,7 @@ checked_impl!(CheckedMul, checked_mul, i16);
 checked_impl!(CheckedMul, checked_mul, i32);
 checked_impl!(CheckedMul, checked_mul, i64);
 checked_impl!(CheckedMul, checked_mul, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedMul, checked_mul, i128);
 
 /// Performs division that returns `None` instead of panicking on division by zero and instead of
@@ -95,7 +95,7 @@ checked_impl!(CheckedDiv, checked_div, u16);
 checked_impl!(CheckedDiv, checked_div, u32);
 checked_impl!(CheckedDiv, checked_div, u64);
 checked_impl!(CheckedDiv, checked_div, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedDiv, checked_div, u128);
 
 checked_impl!(CheckedDiv, checked_div, i8);
@@ -103,7 +103,7 @@ checked_impl!(CheckedDiv, checked_div, i16);
 checked_impl!(CheckedDiv, checked_div, i32);
 checked_impl!(CheckedDiv, checked_div, i64);
 checked_impl!(CheckedDiv, checked_div, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedDiv, checked_div, i128);
 
 /// Performs an integral remainder that returns `None` instead of panicking on division by zero and
@@ -136,7 +136,7 @@ checked_impl!(CheckedRem, checked_rem, u16);
 checked_impl!(CheckedRem, checked_rem, u32);
 checked_impl!(CheckedRem, checked_rem, u64);
 checked_impl!(CheckedRem, checked_rem, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedRem, checked_rem, u128);
 
 checked_impl!(CheckedRem, checked_rem, i8);
@@ -144,7 +144,7 @@ checked_impl!(CheckedRem, checked_rem, i16);
 checked_impl!(CheckedRem, checked_rem, i32);
 checked_impl!(CheckedRem, checked_rem, i64);
 checked_impl!(CheckedRem, checked_rem, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl!(CheckedRem, checked_rem, i128);
 
 macro_rules! checked_impl_unary {
@@ -184,7 +184,7 @@ checked_impl_unary!(CheckedNeg, checked_neg, u16);
 checked_impl_unary!(CheckedNeg, checked_neg, u32);
 checked_impl_unary!(CheckedNeg, checked_neg, u64);
 checked_impl_unary!(CheckedNeg, checked_neg, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl_unary!(CheckedNeg, checked_neg, u128);
 
 checked_impl_unary!(CheckedNeg, checked_neg, i8);
@@ -192,7 +192,7 @@ checked_impl_unary!(CheckedNeg, checked_neg, i16);
 checked_impl_unary!(CheckedNeg, checked_neg, i32);
 checked_impl_unary!(CheckedNeg, checked_neg, i64);
 checked_impl_unary!(CheckedNeg, checked_neg, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_impl_unary!(CheckedNeg, checked_neg, i128);
 
 /// Performs a left shift that returns `None` on overflow.
@@ -229,7 +229,7 @@ checked_shift_impl!(CheckedShl, checked_shl, u16);
 checked_shift_impl!(CheckedShl, checked_shl, u32);
 checked_shift_impl!(CheckedShl, checked_shl, u64);
 checked_shift_impl!(CheckedShl, checked_shl, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_shift_impl!(CheckedShl, checked_shl, u128);
 
 checked_shift_impl!(CheckedShl, checked_shl, i8);
@@ -237,7 +237,7 @@ checked_shift_impl!(CheckedShl, checked_shl, i16);
 checked_shift_impl!(CheckedShl, checked_shl, i32);
 checked_shift_impl!(CheckedShl, checked_shl, i64);
 checked_shift_impl!(CheckedShl, checked_shl, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_shift_impl!(CheckedShl, checked_shl, i128);
 
 /// Performs a right shift that returns `None` on overflow.
@@ -263,7 +263,7 @@ checked_shift_impl!(CheckedShr, checked_shr, u16);
 checked_shift_impl!(CheckedShr, checked_shr, u32);
 checked_shift_impl!(CheckedShr, checked_shr, u64);
 checked_shift_impl!(CheckedShr, checked_shr, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_shift_impl!(CheckedShr, checked_shr, u128);
 
 checked_shift_impl!(CheckedShr, checked_shr, i8);
@@ -271,5 +271,5 @@ checked_shift_impl!(CheckedShr, checked_shr, i16);
 checked_shift_impl!(CheckedShr, checked_shr, i32);
 checked_shift_impl!(CheckedShr, checked_shr, i64);
 checked_shift_impl!(CheckedShr, checked_shr, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 checked_shift_impl!(CheckedShr, checked_shr, i128);

src/ops/mul_add.rs

@@ -67,7 +67,7 @@ macro_rules! mul_add_impl {
 }
 
 mul_add_impl!(MulAdd for isize usize i8 u8 i16 u16 i32 u32 i64 u64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 mul_add_impl!(MulAdd for i128 u128);
 
 #[cfg(feature = "std")]
@@ -98,7 +98,7 @@ macro_rules! mul_add_assign_impl {
 }
 
 mul_add_assign_impl!(MulAddAssign for isize usize i8 u8 i16 u16 i32 u32 i64 u64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 mul_add_assign_impl!(MulAddAssign for i128 u128);
 
 #[cfg(test)]

src/ops/saturating.rs

@@ -26,5 +26,5 @@ macro_rules! saturating_impl {
 }
 
 saturating_impl!(Saturating for isize usize i8 u8 i16 u16 i32 u32 i64 u64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 saturating_impl!(Saturating for i128 u128);

src/ops/wrapping.rs

@@ -32,7 +32,7 @@ wrapping_impl!(WrappingAdd, wrapping_add, u16);
 wrapping_impl!(WrappingAdd, wrapping_add, u32);
 wrapping_impl!(WrappingAdd, wrapping_add, u64);
 wrapping_impl!(WrappingAdd, wrapping_add, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 wrapping_impl!(WrappingAdd, wrapping_add, u128);
 
 wrapping_impl!(WrappingAdd, wrapping_add, i8);
@@ -40,7 +40,7 @@ wrapping_impl!(WrappingAdd, wrapping_add, i16);
 wrapping_impl!(WrappingAdd, wrapping_add, i32);
 wrapping_impl!(WrappingAdd, wrapping_add, i64);
 wrapping_impl!(WrappingAdd, wrapping_add, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 wrapping_impl!(WrappingAdd, wrapping_add, i128);
 
 /// Performs subtraction that wraps around on overflow.
@@ -55,7 +55,7 @@ wrapping_impl!(WrappingSub, wrapping_sub, u16);
 wrapping_impl!(WrappingSub, wrapping_sub, u32);
 wrapping_impl!(WrappingSub, wrapping_sub, u64);
 wrapping_impl!(WrappingSub, wrapping_sub, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 wrapping_impl!(WrappingSub, wrapping_sub, u128);
 
 wrapping_impl!(WrappingSub, wrapping_sub, i8);
@@ -63,7 +63,7 @@ wrapping_impl!(WrappingSub, wrapping_sub, i16);
 wrapping_impl!(WrappingSub, wrapping_sub, i32);
 wrapping_impl!(WrappingSub, wrapping_sub, i64);
 wrapping_impl!(WrappingSub, wrapping_sub, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 wrapping_impl!(WrappingSub, wrapping_sub, i128);
 
 /// Performs multiplication that wraps around on overflow.
@@ -78,7 +78,7 @@ wrapping_impl!(WrappingMul, wrapping_mul, u16);
 wrapping_impl!(WrappingMul, wrapping_mul, u32);
 wrapping_impl!(WrappingMul, wrapping_mul, u64);
 wrapping_impl!(WrappingMul, wrapping_mul, usize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 wrapping_impl!(WrappingMul, wrapping_mul, u128);
 
 wrapping_impl!(WrappingMul, wrapping_mul, i8);
@@ -86,7 +86,7 @@ wrapping_impl!(WrappingMul, wrapping_mul, i16);
 wrapping_impl!(WrappingMul, wrapping_mul, i32);
 wrapping_impl!(WrappingMul, wrapping_mul, i64);
 wrapping_impl!(WrappingMul, wrapping_mul, isize);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 wrapping_impl!(WrappingMul, wrapping_mul, i128);
 
 // Well this is a bit funny, but all the more appropriate.

src/pow.rs

@@ -99,22 +99,22 @@ pow_impl!(i64, u16, u32, i64::pow);
 pow_impl!(i64, u32, u32, i64::pow);
 pow_impl!(i64, usize);
 
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(u128, u8, u32, u128::pow);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(u128, u16, u32, u128::pow);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(u128, u32, u32, u128::pow);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(u128, usize);
 
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(i128, u8, u32, i128::pow);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(i128, u16, u32, i128::pow);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(i128, u32, u32, i128::pow);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(i128, usize);
 
 pow_impl!(usize, u8, u32, usize::pow);
@@ -133,9 +133,9 @@ pow_impl!(Wrapping<u32>);
 pow_impl!(Wrapping<i32>);
 pow_impl!(Wrapping<u64>);
 pow_impl!(Wrapping<i64>);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(Wrapping<u128>);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 pow_impl!(Wrapping<i128>);
 pow_impl!(Wrapping<usize>);
 pow_impl!(Wrapping<isize>);

src/sign.rs

@@ -74,7 +74,7 @@ macro_rules! signed_impl {
 
 signed_impl!(isize i8 i16 i32 i64);
 
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 signed_impl!(i128);
 
 impl<T: Signed> Signed for Wrapping<T> where Wrapping<T>: Num + Neg<Output=Wrapping<T>>
@@ -186,7 +186,7 @@ macro_rules! empty_trait_impl {
 }
 
 empty_trait_impl!(Unsigned for usize u8 u16 u32 u64);
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 empty_trait_impl!(Unsigned for u128);
 
 impl<T: Unsigned> Unsigned for Wrapping<T> where Wrapping<T>: Num {}

tests/cast.rs

@@ -13,7 +13,7 @@ use num_traits::cast::*;
 use core::{i8, i16, i32, i64, isize};
 use core::{u8, u16, u32, u64, usize};
 use core::{f32, f64};
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 use core::{i128, u128};
 
 use core::mem;
@@ -144,7 +144,7 @@ fn cast_to_unsigned_int_checks_overflow() {
 }
 
 #[test]
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 fn cast_to_i128_checks_overflow() {
     let big_f: f64 = 1.0e123;
     let normal_f: f64 = 1.0;
@@ -240,7 +240,7 @@ fn cast_float_to_int_edge_cases() {
 }
 
 #[test]
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 fn cast_float_to_i128_edge_cases() {
     float_test_edge!(f32 -> i128 u128);
     float_test_edge!(f64 -> i128 u128);
@@ -299,7 +299,7 @@ fn cast_int_to_int_edge_cases() {
 }
 
 #[test]
-#[cfg(feature = "i128")]
+#[cfg(has_i128)]
 fn cast_int_to_128_edge_cases() {
     use core::cmp::Ordering::*;