Fix protocol if "all" is not enabled.

src/sys/windows.rs

@@ -23,12 +23,12 @@ use windows_sys::Win32::Foundation::{SetHandleInformation, HANDLE, HANDLE_FLAG_I
 use windows_sys::Win32::Networking::WinSock::{
     self, tcp_keepalive, FIONBIO, IN6_ADDR, IN6_ADDR_0, INVALID_SOCKET, IN_ADDR, IN_ADDR_0,
     POLLERR, POLLHUP, POLLRDNORM, POLLWRNORM, SD_BOTH, SD_RECEIVE, SD_SEND, SIO_KEEPALIVE_VALS,
-    SOCKET_ERROR, SO_PROTOCOL_INFOW, WSABUF, WSAEMSGSIZE, WSAESHUTDOWN, WSAPOLLFD,
-    WSAPROTOCOL_INFOW, WSA_FLAG_NO_HANDLE_INHERIT, WSA_FLAG_OVERLAPPED,
+    SOCKET_ERROR, WSABUF, WSAEMSGSIZE, WSAESHUTDOWN, WSAPOLLFD, WSAPROTOCOL_INFOW,
+    WSA_FLAG_NO_HANDLE_INHERIT, WSA_FLAG_OVERLAPPED,
 };
 use windows_sys::Win32::System::Threading::INFINITE;
 
-use crate::{MsgHdr, Protocol, RecvFlags, SockAddr, TcpKeepalive, Type};
+use crate::{MsgHdr, RecvFlags, SockAddr, TcpKeepalive, Type};
 
 #[allow(non_camel_case_types)]
 pub(crate) type c_int = std::os::raw::c_int;
@@ -924,13 +924,15 @@ impl crate::Socket {
     /// Returns the [`Protocol`] of this socket by checking the `SO_PROTOCOL_INFOW`
     /// option on this socket.
     #[cfg(feature = "all")]
-    pub fn protocol(&self) -> io::Result<Option<Protocol>> {
+    pub fn protocol(&self) -> io::Result<Option<crate::Protocol>> {
+        use windows_sys::Win32::Networking::WinSock::SO_PROTOCOL_INFOW;
+
         let info = unsafe {
             getsockopt::<WSAPROTOCOL_INFOW>(self.as_raw(), SOL_SOCKET, SO_PROTOCOL_INFOW)?
         };
         match info.iProtocol {
             0 => Ok(None),
-            p => Ok(Some(Protocol::from(p))),
+            p => Ok(Some(crate::Protocol::from(p))),
         }
     }
 }