Example program:

static int static_value = 0;

int
a_function_to_call()
{
    static_value++;
    return static_value;
}

int main (int argc, char const *argv[])
{   
    a_function_to_call();
    return 0;
}

Compiling this as a c++ program with -O0 and -g and trying to call or print the function pointer 'a_function_to_call' fails.

Output:

(lldb) b main
(lldb) r
...
(lldb) expression a_function_to_call                                 
error: use of undeclared identifier 'a_function_to_call'
error: 1 errors parsing expression
(lldb) expression a_function_to_call()
error: use of undeclared identifier 'a_function_to_call'
error: 1 errors parsing expression