Rollup merge of rust-lang#74409 - LukasKalbertodt:improve-debug-impl-of-socketaddr-ipaddr, r=Amanieu

Change Debug impl of SocketAddr and IpAddr to match their Display output

This has already been done for `SocketAddrV4`, `SocketAddrV6`, `IpAddrV4` and `IpAddrV6`. I don't see a point to keep the rather bad to read derived impl, especially so when pretty printing:

    V4(
        127.0.0.1
    )

From the `Display`, one can easily and unambiguously see if it's V4 or V6. Two examples:

```
127.0.0.1:443
[2001:db8:85a3::8a2e:370:7334]:443
```

Luckily the docs explicitly state that `Debug` output is not stable and that it may be changed at any time.

Using `Display` as `Debug` is very convenient for configuration structs (e.g. for webservers) that often just have a `derive(Debug)` and are printed that way to the one starting the server.

Author: tmandry

library/std/src/net/addr.rs

@@ -37,7 +37,7 @@ use crate::vec;
 /// assert_eq!(socket.port(), 8080);
 /// assert_eq!(socket.is_ipv4(), true);
 /// ```
-#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, PartialOrd, Ord)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub enum SocketAddr {
     /// An IPv4 socket address.
@@ -597,6 +597,13 @@ impl fmt::Display for SocketAddr {
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl fmt::Debug for SocketAddr {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self, fmt)
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Display for SocketAddrV4 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

library/std/src/net/ip.rs

@@ -40,7 +40,7 @@ use crate::sys_common::{AsInner, FromInner};
 /// assert_eq!(localhost_v4.is_ipv4(), true);
 /// ```
 #[stable(feature = "ip_addr", since = "1.7.0")]
-#[derive(Copy, Clone, Eq, PartialEq, Debug, Hash, PartialOrd, Ord)]
+#[derive(Copy, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
 pub enum IpAddr {
     /// An IPv4 address.
     #[stable(feature = "ip_addr", since = "1.7.0")]
@@ -802,6 +802,13 @@ impl fmt::Display for IpAddr {
     }
 }
 
+#[stable(feature = "ip_addr", since = "1.7.0")]
+impl fmt::Debug for IpAddr {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self, fmt)
+    }
+}
+
 #[stable(feature = "ip_from_ip", since = "1.16.0")]
 impl From<Ipv4Addr> for IpAddr {
     /// Copies this address to a new `IpAddr::V4`.