I found this by running "make test" on musl build of Python.

$ cat test_asctime.c

#include <time.h>

#include <stdio.h>

int main()

{

    char *c = asctime(0);

    printf("After asctime\n");

    if (c) printf("c=%s", c);

}

$ gcc test_asctime.c   -o test_asctime

$ test_asctime

After asctime

$ musl-gcc test_asctime.c   -o test_asctime

$ test_asctime

Segmentation fault (core dumped)

$