Print nested_exception with no nested_ptr

Question

I\'m trying to print nested exceptions using the following example code from cppreference.com:

void print_exception(const std::exception& e, int level =  0)
         


        

Answer 1

You may write something like:

// Similar to rethrow_if_nested
// but does nothing instead of calling std::terminate
// when std::nested_exception is nullptr.

template <typename E>
std::enable_if_t<!std::is_polymorphic<E>::value>
my_rethrow_if_nested(const E&) {}

template <typename E>
std::enable_if_t<std::is_polymorphic<E>::value>
my_rethrow_if_nested(const E& e)
{
    const auto* p = dynamic_cast<const std::nested_exception*>(std::addressof(e));

    if (p && p->nested_ptr()) {
        p->rethrow_nested();
    }
}

Demo