Update to Visual Studio 2017.

src/luasocket.c

@@ -64,7 +64,7 @@ static luaL_Reg func[] = {
 * Skip a few arguments
 \*-------------------------------------------------------------------------*/
 static int global_skip(lua_State *L) {
-    int amount = luaL_checkinteger(L, 1);
+    int amount = (int) luaL_checkinteger(L, 1);
     int ret = lua_gettop(L) - amount - 1;
     return ret >= 0 ? ret : 0;
 }

src/makefile

@@ -386,7 +386,7 @@ $(UNIX_SO): $(UNIX_OBJS)
 $(SERIAL_SO): $(SERIAL_OBJS)
 	$(LD) $(SERIAL_OBJS) $(LDFLAGS)$@
 
-install: 
+install:
 	$(INSTALL_DIR) $(INSTALL_TOP_LDIR)
 	$(INSTALL_DATA) $(TO_TOP_LDIR) $(INSTALL_TOP_LDIR)
 	$(INSTALL_DIR) $(INSTALL_SOCKET_LDIR)

src/mime.c

@@ -654,7 +654,7 @@ static int eolprocess(int c, int last, const char *marker,
 \*-------------------------------------------------------------------------*/
 static int mime_global_eol(lua_State *L)
 {
-    int ctx = luaL_checkinteger(L, 1);
+    int ctx = (int) luaL_checkinteger(L, 1);
     size_t isize = 0;
     const char *input = luaL_optlstring(L, 2, NULL, &isize);
     const char *last = input + isize;

src/wsocket.c

@@ -131,11 +131,11 @@ int socket_connect(p_socket ps, SA *addr, socklen_t len, p_timeout tm) {
     /* we wait until something happens */
     err = socket_waitfd(ps, WAITFD_C, tm);
     if (err == IO_CLOSED) {
-        int len = sizeof(err);
+        int elen = sizeof(err);
         /* give windows time to set the error (yes, disgusting) */
         Sleep(10);
         /* find out why we failed */
-        getsockopt(*ps, SOL_SOCKET, SO_ERROR, (char *)&err, &len);
+        getsockopt(*ps, SOL_SOCKET, SO_ERROR, (char *)&err, &elen);
         /* we KNOW there was an error. if 'why' is 0, we will return
         * "unknown error", but it's not really our fault */
         return err > 0? err: IO_UNKNOWN;