Rollup merge of rust-lang#112606 - clarfonthey:ip-display, r=thomcc

Alter `Display` for `Ipv6Addr` for IPv4-compatible addresses

ACP: rust-lang/libs-team#239

Author: compiler-errors

library/core/src/net/ip_addr.rs

@@ -1770,14 +1770,8 @@ impl fmt::Display for Ipv6Addr {
                 f.write_str("::")
             } else if self.is_loopback() {
                 f.write_str("::1")
-            } else if let Some(ipv4) = self.to_ipv4() {
-                match segments[5] {
-                    // IPv4 Compatible address
-                    0 => write!(f, "::{}", ipv4),
-                    // IPv4 Mapped address
-                    0xffff => write!(f, "::ffff:{}", ipv4),
-                    _ => unreachable!(),
-                }
+            } else if let Some(ipv4) = self.to_ipv4_mapped() {
+                write!(f, "::ffff:{}", ipv4)
             } else {
                 #[derive(Copy, Clone, Default)]
                 struct Span {

library/core/tests/net/ip_addr.rs

@@ -139,7 +139,7 @@ fn ipv6_addr_to_string() {
 
     // ipv4-compatible address
     let a1 = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0xc000, 0x280);
-    assert_eq!(a1.to_string(), "::192.0.2.128");
+    assert_eq!(a1.to_string(), "::c000:280");
 
     // v6 address with no zero segments
     assert_eq!(Ipv6Addr::new(8, 9, 10, 11, 12, 13, 14, 15).to_string(), "8:9:a:b:c:d:e:f");
@@ -316,7 +316,7 @@ fn ip_properties() {
 
     check!("::", unspec);
     check!("::1", loopback);
-    check!("::0.0.0.2", global);
+    check!("::2", global);
     check!("1::", global);
     check!("fc00::");
     check!("fdff:ffff::");
@@ -607,7 +607,7 @@ fn ipv6_properties() {
 
     check!("::1", &[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1], loopback);
 
-    check!("::0.0.0.2", &[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2], global | unicast_global);
+    check!("::2", &[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2], global | unicast_global);
 
     check!("1::", &[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], global | unicast_global);
 

library/core/tests/net/socket_addr.rs

@@ -34,7 +34,7 @@ fn ipv6_socket_addr_to_string() {
     // IPv4-compatible address.
     assert_eq!(
         SocketAddrV6::new(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0xc000, 0x280), 8080, 0, 0).to_string(),
-        "[::192.0.2.128]:8080"
+        "[::c000:280]:8080"
     );
 
     // IPv6 address with no zero segments.

library/std/src/net/socket_addr/tests.rs

@@ -85,7 +85,7 @@ fn ipv6_socket_addr_to_string() {
     // IPv4-compatible address.
     assert_eq!(
         SocketAddrV6::new(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0xc000, 0x280), 8080, 0, 0).to_string(),
-        "[::192.0.2.128]:8080"
+        "[::c000:280]:8080"
     );
 
     // IPv6 address with no zero segments.