Fix MSVC compiler noreturn related warnings and add extra

safety asserts to the functions that do not return on all
control paths.

nmap_error.h

@@ -121,11 +121,18 @@
 extern "C" {
 #endif
 
+#ifdef WIN32
+__declspec(noreturn)
+#endif  
 void fatal(const char *fmt, ...)
      __attribute__ ((noreturn))
      __attribute__ ((format (printf, 1, 2)));
 void error(const char *fmt, ...)
      __attribute__ ((format (printf, 1, 2)));
+
+#ifdef WIN32
+__declspec(noreturn)
+#endif
 void pfatal(const char *err, ...)
      __attribute__ ((noreturn))
      __attribute__ ((format (printf, 1, 2)));

tcpip.cc

@@ -499,6 +499,9 @@ int send_ip_packet(int sd, struct eth_nfo *eth, u8 *packet,
     return send_ipv6_packet(sd, eth, packet, packetlen);
 
   fatal("%s only understands IP versions 4 and 6 (got %u)", __func__, ip->ip_v);
+
+  /* This should not be reached. Just in case. */
+  assert(0);
 }
 
 

traceroute.cc

@@ -724,6 +724,9 @@ public:
     } else {
       fatal("Unknown address family %u in %s.", source->ss_family, __func__);
     }
+
+    /* This should not be reached. Just in case. */
+    assert(0);
   }
 };