Add rustc_diagnostic_item for IP addresses.

Author: reitermarkus

library/std/src/net/ip_addr.rs

@@ -29,13 +29,16 @@ use super::display_buffer::DisplayBuffer;
 /// assert_eq!(localhost_v4.is_ipv6(), false);
 /// assert_eq!(localhost_v4.is_ipv4(), true);
 /// ```
+#[cfg_attr(not(test), rustc_diagnostic_item = "IpAddr")]
 #[stable(feature = "ip_addr", since = "1.7.0")]
 #[derive(Copy, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
 pub enum IpAddr {
     /// An IPv4 address.
+    #[cfg_attr(not(test), rustc_diagnostic_item = "ip_addr_variant_v4")]
     #[stable(feature = "ip_addr", since = "1.7.0")]
     V4(#[stable(feature = "ip_addr", since = "1.7.0")] Ipv4Addr),
     /// An IPv6 address.
+    #[cfg_attr(not(test), rustc_diagnostic_item = "ip_addr_variant_v6")]
     #[stable(feature = "ip_addr", since = "1.7.0")]
     V6(#[stable(feature = "ip_addr", since = "1.7.0")] Ipv6Addr),
 }
@@ -72,6 +75,7 @@ pub enum IpAddr {
 /// assert!("0xcb.0x0.0x71.0x00".parse::<Ipv4Addr>().is_err()); // all octets are in hex
 /// ```
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
+#[cfg_attr(not(test), rustc_diagnostic_item = "Ipv4Addr")]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Ipv4Addr {
     octets: [u8; 4],
@@ -154,6 +158,7 @@ pub struct Ipv4Addr {
 /// assert_eq!(localhost.is_loopback(), true);
 /// ```
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
+#[cfg_attr(not(test), rustc_diagnostic_item = "Ipv6Addr")]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Ipv6Addr {
     octets: [u8; 16],