$ make conftest
cc -O2 -pipe   conftest.c  -o conftest
conftest.c:7:5: error: conflicting types for 'test'
int test(fmt)
    ^
conftest.c:4:5: note: previous declaration is here
int test(char*,...);
    ^
conftest.c:14:2: error: 'va_start' used in function with fixed args
        va_start(ap,fmt);
        ^
/usr/include/stdarg.h:45:2: note: instantiated from:
        __builtin_va_start((ap), (last))
        ^
3 diagnostics generated.
*** Error code 1

Stop in /home/ed.