sockets(windows): correctly obtain socket family for accept

src/sys/private/sockets_windows.nim

@@ -406,11 +406,13 @@ template acceptCommon(listener: SocketFD, conn: var Handle[SocketFD],
   # Common parts for dealing with AcceptEx, `overlapped` dictates whether the
   # operation should be done in an overlapped manner and yields an overlapped
   # socket.
-  const addressFamily =
-    when endpoint is IP4Endpoint:
-      AF_INET
-    elif endpoint is IP6Endpoint:
-      AF_INET6
+
+  # TODO : cache this data
+  let lendpoint = getLocalEndpoint(listener)
+  let addressFamily =
+    case lendpoint.kind
+    of V4: AF_INET
+    of V6: AF_INET6
 
   conn = initHandle:
     SocketFD:
@@ -518,12 +520,15 @@ template tcpAsyncAccept() {.dirty.} =
   result.conn = AsyncConn[TCP] newAsyncSocket(move conn)
 
 template tcpLocalEndpoint() {.dirty.} =
+  getLocalEndpoint(l.fd)
+
+proc getLocalEndpoint(fd: SocketFD): IPEndpoint =
   var
     saddr: SockaddrStorage
     endpointLen = cint sizeof(saddr)
 
   if getsockname(
-    wincore.Socket(l.fd),
+    wincore.Socket(fd),
     cast[ptr sockaddr](addr saddr),
     addr endpointLen
   ) == SocketError: