define _GNU_SOURCE This resolves resolve implict declaration error xmalloc.c: In function ‘xasprintf’: xmalloc.c:114:13: error: implicit declaration of function ‘vasprintf’; did you mean ‘xasprintf’? [-Werror=implicit-function-declaration] 114 | i = vasprintf(ret, fmt, ap); | ^~~~~~~~~ | xasprintf _GNU_SOURCE macro enables vasprintf function declaration.
