libstd: convert `Duration` binops to by value

src/libstd/time/duration.rs

@@ -276,6 +276,8 @@ fn neg(&self) -> Duration {
     }
 }
 
+// NOTE(stage0): Remove impl after a snapshot
+#[cfg(stage0)]
 impl Add<Duration,Duration> for Duration {
     fn add(&self, rhs: &Duration) -> Duration {
         let mut secs = self.secs + rhs.secs;
@@ -288,6 +290,21 @@ fn add(&self, rhs: &Duration) -> Duration {
     }
 }
 
+#[cfg(not(stage0))]  // NOTE(stage0): Remove cfg after a snapshot
+impl Add<Duration, Duration> for Duration {
+    fn add(self, rhs: Duration) -> Duration {
+        let mut secs = self.secs + rhs.secs;
+        let mut nanos = self.nanos + rhs.nanos;
+        if nanos >= NANOS_PER_SEC {
+            nanos -= NANOS_PER_SEC;
+            secs += 1;
+        }
+        Duration { secs: secs, nanos: nanos }
+    }
+}
+
+// NOTE(stage0): Remove impl after a snapshot
+#[cfg(stage0)]
 impl Sub<Duration,Duration> for Duration {
     fn sub(&self, rhs: &Duration) -> Duration {
         let mut secs = self.secs - rhs.secs;
@@ -300,6 +317,21 @@ fn sub(&self, rhs: &Duration) -> Duration {
     }
 }
 
+#[cfg(not(stage0))]  // NOTE(stage0): Remove cfg after a snapshot
+impl Sub<Duration, Duration> for Duration {
+    fn sub(self, rhs: Duration) -> Duration {
+        let mut secs = self.secs - rhs.secs;
+        let mut nanos = self.nanos - rhs.nanos;
+        if nanos < 0 {
+            nanos += NANOS_PER_SEC;
+            secs -= 1;
+        }
+        Duration { secs: secs, nanos: nanos }
+    }
+}
+
+// NOTE(stage0): Remove impl after a snapshot
+#[cfg(stage0)]
 impl Mul<i32,Duration> for Duration {
     fn mul(&self, rhs: &i32) -> Duration {
         // Multiply nanoseconds as i64, because it cannot overflow that way.
@@ -310,6 +342,19 @@ fn mul(&self, rhs: &i32) -> Duration {
     }
 }
 
+#[cfg(not(stage0))]  // NOTE(stage0): Remove cfg after a snapshot
+impl Mul<i32, Duration> for Duration {
+    fn mul(self, rhs: i32) -> Duration {
+        // Multiply nanoseconds as i64, because it cannot overflow that way.
+        let total_nanos = self.nanos as i64 * rhs as i64;
+        let (extra_secs, nanos) = div_mod_floor_64(total_nanos, NANOS_PER_SEC as i64);
+        let secs = self.secs * rhs as i64 + extra_secs;
+        Duration { secs: secs, nanos: nanos as i32 }
+    }
+}
+
+// NOTE(stage0): Remove impl after a snapshot
+#[cfg(stage0)]
 impl Div<i32,Duration> for Duration {
     fn div(&self, rhs: &i32) -> Duration {
         let mut secs = self.secs / *rhs as i64;
@@ -328,6 +373,25 @@ fn div(&self, rhs: &i32) -> Duration {
     }
 }
 
+#[cfg(not(stage0))]  // NOTE(stage0): Remove cfg after a snapshot
+impl Div<i32, Duration> for Duration {
+    fn div(self, rhs: i32) -> Duration {
+        let mut secs = self.secs / rhs as i64;
+        let carry = self.secs - secs * rhs as i64;
+        let extra_nanos = carry * NANOS_PER_SEC as i64 / rhs as i64;
+        let mut nanos = self.nanos / rhs + extra_nanos as i32;
+        if nanos >= NANOS_PER_SEC {
+            nanos -= NANOS_PER_SEC;
+            secs += 1;
+        }
+        if nanos < 0 {
+            nanos += NANOS_PER_SEC;
+            secs -= 1;
+        }
+        Duration { secs: secs, nanos: nanos }
+    }
+}
+
 impl fmt::Show for Duration {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         // technically speaking, negative duration is not valid ISO 8601,