-Wincompatible-pointer-types error in init.c, if gcc version >= 14

[akira-kurogane]

When remaking my lwip-using unikernel on a new computer the build terminated on this error:

/home/akira/avar_src/app-mongod403/w/libs/lwip/init.c: In function ‘liblwip_init’:
/home/akira/avar_src/app-mongod403/w/libs/lwip/init.c:402:58: error: passing argument 2 of ‘dns_setserver’ from incompatible pointer type [-Wincompatible-pointer-types]
  402 |                                 dns_setserver(nb_dns4++, &dns4);
      |                                                          ^~~~~
      |                                                          |
      |                                                          ip4_addr_t * {aka struct ip4_addr *}

It appears that gcc version >= 14 will make -Wincompatible-pointer-types an error instead of warning by default: https://gcc.gnu.org/gcc-14/porting_to.html

My workaround for now is simply to add -Wno-incompatible-pointer-types (or -Wno-error=incompatible-pointer-types?) to the LIBLWIP_CFLAGS line in lwip's Makefile.uk.