3 files changed, 54 insertions, 14 deletions

diff --git a/src/libstd/sys/unix/mod.rs b/src/libstd/sys/unix/mod.rs
index 12a877f7478..f0fd42fc99b 100644
--- a/src/libstd/sys/unix/mod.rs
+++ b/src/libstd/sys/unix/mod.rs
@@ -12,8 +12,6 @@
 
 use io::{self, ErrorKind};
 use libc;
-use num::One;
-use ops::Neg;
 
 #[cfg(target_os = "android")]   pub use os::android as platform;
 #[cfg(target_os = "bitrig")]    pub use os::bitrig as platform;
@@ -123,9 +121,23 @@ pub fn decode_error_kind(errno: i32) -> ErrorKind {
     }
 }
 
-pub fn cvt<T: One + PartialEq + Neg<Output=T>>(t: T) -> io::Result<T> {
-    let one: T = T::one();
-    if t == -one {
+#[doc(hidden)]
+pub trait IsMinusOne {
+    fn is_minus_one(&self) -> bool;
+}
+
+macro_rules! impl_is_minus_one {
+    ($($t:ident)*) => ($(impl IsMinusOne for $t {
+        fn is_minus_one(&self) -> bool {
+            *self == -1
+        }
+    })*)
+}
+
+impl_is_minus_one! { i8 i16 i32 i64 isize }
+
+pub fn cvt<T: IsMinusOne>(t: T) -> io::Result<T> {
+    if t.is_minus_one() {
         Err(io::Error::last_os_error())
     } else {
         Ok(t)
@@ -133,7 +145,8 @@ pub fn cvt<T: One + PartialEq + Neg<Output=T>>(t: T) -> io::Result<T> {
 }
 
 pub fn cvt_r<T, F>(mut f: F) -> io::Result<T>
-    where T: One + PartialEq + Neg<Output=T>, F: FnMut() -> T
+    where T: IsMinusOne,
+          F: FnMut() -> T
 {
     loop {
         match cvt(f()) {
diff --git a/src/libstd/sys/windows/mod.rs b/src/libstd/sys/windows/mod.rs
index 6dd4f4c3e75..12219c1e9d4 100644
--- a/src/libstd/sys/windows/mod.rs
+++ b/src/libstd/sys/windows/mod.rs
@@ -14,7 +14,6 @@ use prelude::v1::*;
 
 use ffi::{OsStr, OsString};
 use io::{self, ErrorKind};
-use num::Zero;
 use os::windows::ffi::{OsStrExt, OsStringExt};
 use path::PathBuf;
 use time::Duration;
@@ -178,8 +177,22 @@ pub fn truncate_utf16_at_nul<'a>(v: &'a [u16]) -> &'a [u16] {
     }
 }
 
-fn cvt<I: PartialEq + Zero>(i: I) -> io::Result<I> {
-    if i == I::zero() {
+trait IsZero {
+    fn is_zero(&self) -> bool;
+}
+
+macro_rules! impl_is_zero {
+    ($($t:ident)*) => ($(impl IsZero for $t {
+        fn is_zero(&self) -> bool {
+            *self == 0
+        }
+    })*)
+}
+
+impl_is_zero! { i8 i16 i32 i64 isize u8 u16 u32 u64 usize }
+
+fn cvt<I: IsZero>(i: I) -> io::Result<I> {
+    if i.is_zero() {
         Err(io::Error::last_os_error())
     } else {
         Ok(i)
diff --git a/src/libstd/sys/windows/net.rs b/src/libstd/sys/windows/net.rs
index b05dcf42a33..71e164f012f 100644
--- a/src/libstd/sys/windows/net.rs
+++ b/src/libstd/sys/windows/net.rs
@@ -17,8 +17,6 @@ use io::{self, Read};
 use libc::{c_int, c_void, c_ulong};
 use mem;
 use net::{SocketAddr, Shutdown};
-use num::One;
-use ops::Neg;
 use ptr;
 use sync::Once;
 use sys::c;
@@ -60,11 +58,26 @@ fn last_error() -> io::Error {
     io::Error::from_raw_os_error(unsafe { c::WSAGetLastError() })
 }
 
+#[doc(hidden)]
+pub trait IsMinusOne {
+    fn is_minus_one(&self) -> bool;
+}
+
+macro_rules! impl_is_minus_one {
+    ($($t:ident)*) => ($(impl IsMinusOne for $t {
+        fn is_minus_one(&self) -> bool {
+            *self == -1
+        }
+    })*)
+}
+
+impl_is_minus_one! { i8 i16 i32 i64 isize }
+
 /// Checks if the signed integer is the Windows constant `SOCKET_ERROR` (-1)
 /// and if so, returns the last error from the Windows socket interface. This
 /// function must be called before another call to the socket API is made.
-pub fn cvt<T: One + PartialEq + Neg<Output=T>>(t: T) -> io::Result<T> {
-    if t == -T::one() {
+pub fn cvt<T: IsMinusOne>(t: T) -> io::Result<T> {
+    if t.is_minus_one() {
         Err(last_error())
     } else {
         Ok(t)
@@ -82,7 +95,8 @@ pub fn cvt_gai(err: c_int) -> io::Result<()> {
 
 /// Just to provide the same interface as sys/unix/net.rs
 pub fn cvt_r<T, F>(mut f: F) -> io::Result<T>
-    where T: One + PartialEq + Neg<Output=T>, F: FnMut() -> T
+    where T: IsMinusOne,
+          F: FnMut() -> T
 {
     cvt(f())
 }