It calls mbsrtowcs with an incorrect parameter type:

int
main ()
{
wchar_t *out;char *in;char *res;
     res=setlocale(LC_CTYPE,"");res=in;
     mbsrtowcs(out, &res, 2, NULL);
     wcswidth(out,2);
  ;
  return 0;
}

The type of res should be const char *, not char *.

Reproducible: Always