Make delegation methods of `std::net::IpAddr` unstable const

Make the following methods of `std::net::IpAddr` unstable const under the `const_ip` feature:
- `is_unspecified`
- `is_loopback`
- `is_global`
- `is_multicast`

Also adds a test for these methods in a const context.

Possible because these methods delegate to the inner `Ipv4Addr` or `Ipv6Addr`, which were made const, and the recent stabilization of const control flow.

Part of #76205

1 files changed, 19 insertions, 0 deletions

diff --git a/library/std/src/net/ip/tests.rs b/library/std/src/net/ip/tests.rs
index 76a0ae8b945..d9fbdd1b5e7 100644
--- a/library/std/src/net/ip/tests.rs
+++ b/library/std/src/net/ip/tests.rs
@@ -918,3 +918,22 @@ fn ipv6_const() {
     const IP_V4: Option<Ipv4Addr> = IP_ADDRESS.to_ipv4();
     assert_eq!(IP_V4.unwrap(), Ipv4Addr::new(0, 0, 0, 1));
 }
+
+#[test]
+fn ip_const() {
+    // test that the methods of `IpAddr` are usable in a const context
+
+    const IP_ADDRESS: IpAddr = IpAddr::V4(Ipv4Addr::LOCALHOST);
+
+    const IS_UNSPECIFIED: bool = IP_ADDRESS.is_unspecified();
+    assert!(!IS_UNSPECIFIED);
+
+    const IS_LOOPBACK: bool = IP_ADDRESS.is_loopback();
+    assert!(IS_LOOPBACK);
+
+    const IS_GLOBAL: bool = IP_ADDRESS.is_global();
+    assert!(!IS_GLOBAL);
+
+    const IS_MULTICAST: bool = IP_ADDRESS.is_multicast();
+    assert!(!IS_MULTICAST);
+}