/opt/IBM/openxlC/17.1.1/bin/ibm-clang -pthread   -Wall -Wextra -Werror=implicit-function-declaration stdio/vasprintf.c -o stdio/vasprintf -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt  -liconv -latomic
stdio/vasprintf.c:13:12: error: call to undeclared function 'vasprintf'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
        int ret = vasprintf(&buf, format, ap);
                  ^
stdio/vasprintf.c:13:12: note: did you mean 'vsprintf'?
/usr/include/stdio.h:334:21: note: 'vsprintf' declared here
extern int      _NOTHROW(vsprintf, (char *__restrict__, const char *__restrict__, va_list));
                         ^
/usr/include/comp_macros.h:51:26: note: expanded from macro '_NOTHROW'
#define _NOTHROW(_F, _B) _F _B
                         ^
1 error generated.