In C++, what is the recommended way to handle errors that occur inside a destructor?

Introduction / Context:
Exception safety in C++ is a subtle topic, and destructors play a critical role during stack unwinding when an exception is thrown. If a destructor itself throws an exception while another one is already being processed, the C++ runtime will call std::terminate, abruptly ending the program. Therefore, best practice guidelines emphasise how to handle errors inside destructors. This question checks your understanding of those guidelines.

Given Data / Assumptions:

• We are working with C++ and its standard exception handling model.
• Destructors may run during stack unwinding when an exception is already active.
• Throwing another exception from a destructor can lead to undefined behaviour or program termination.

Concept / Approach:
The general rule is that destructors should not allow exceptions to escape. If a destructor encounters an error, it should handle it internally, for example by logging the problem, releasing resources as best as possible and continuing. In rare cases where the error is truly unrecoverable, the destructor can deliberately call std::terminate or abort to end the program in a controlled way. What it must not do is throw an exception that can escape to the caller, because this can cause a second active exception during stack unwinding.

Step-by-Step Solution:
Step 1: Recognise that throwing exceptions from destructors is dangerous, especially during stack unwinding.Step 2: Understand that recommended practice is to prevent exceptions from propagating out of destructors.Step 3: Option B states that you should avoid letting exceptions escape and, in unrecoverable cases, log the error or call terminate rather than throwing.Step 4: Option A directly contradicts best practices by encouraging throwing from destructors.Step 5: Option C claims that both throwing and terminate are equally safe, which is misleading, and option D incorrectly states that destructors cannot handle errors at all, so option B is correct.

Verification / Alternative check:
Guidelines from sources such as the C++ Core Guidelines and standard library documentation emphasise that destructors should not throw. Many standard library destructors are declared noexcept to enforce this rule. Books and articles on exception safety explain that if a destructor throws during stack unwinding, std::terminate is called. These references support the recommendation that destructors handle errors locally and avoid propagating exceptions, matching the behaviour described in option B.

Why Other Options Are Wrong:
Option A suggests always throwing from destructors so that callers can catch errors, but this is exactly what can cause program termination if an exception is already in flight. Option C ignores the distinction between safe and unsafe patterns and can mislead developers into writing fragile code. Option D claims that destructors cannot handle errors at all, which is untrue; they can handle errors internally, they just should not let exceptions escape.

Common Pitfalls:
A common mistake is to treat destructors like normal functions and freely throw exceptions from them. Another pitfall is to ignore failures in clean up code altogether without logging or monitoring. The balanced approach is to handle errors locally in the destructor, log or signal them through other channels if necessary and ensure that no exceptions leak out. In exam answers, always stress that exceptions must not escape destructors.

Final Answer:
Avoid letting exceptions escape from the destructor; if an unrecoverable error occurs, log it or call terminate rather than throwing.