Impl From<Ipv4Addr, Ipv6Addr> for IpAddr.

Fixes rust-lang/rfcs#1816.

Author: Yamakaky

src/libstd/net/ip.rs

@@ -524,6 +524,18 @@ impl fmt::Display for IpAddr {
     }
 }
 
+impl From<Ipv4Addr> for IpAddr {
+    fn from(ipv4: Ipv4Addr) -> IpAddr {
+        IpAddr::V4(ipv4)
+    }
+}
+
+impl From<Ipv6Addr> for IpAddr {
+    fn from(ipv6: Ipv6Addr) -> IpAddr {
+        IpAddr::V6(ipv6)
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Display for Ipv4Addr {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {