Virtual destructor for pure abstract base classes

Question

I have seen here and here that a good rule of thumb is to use virtual destructors for every class that is intended as a base class. I have a pure abstract base class (only contains pure virtual functions and no data members; intended to be used as an interface).

class A {
    public:
        virtual void foo() = 0;
};

Is it possible to add a virtual destructor to this class without creating an implementation file (this class is defined in a header file included in several .cpp files) just for an empty destructor while also avoiding clang and g++ warnings such as -Wweak-vtables? I cannot put the empty definition in the header file with the pure abstract class because I will get multiple definitions of the destructor.

" will get multiple definitions of the destructor." - no, you won't, if it is inline in the class - have you tried? — , Nov 16 '18 at 22:19
@Neil Butterworth This triggers the -Wweak-vtables from clang — Adam Sperry, Nov 16 '18 at 22:21
Well, that's a problem with clang - it is perfectly valid C++. — , Nov 16 '18 at 22:22
[What is the meaning of clang's -Wweak-vtables?](https://stackoverflow.com/questions/23746941/what-is-the-meaning-of-clangs-wweak-vtables) — Yksisarvinen, Nov 16 '18 at 22:26
@juanchopanza This is a different question from that one since the answer to that question triggers the -Wweak-vtables from clang — Adam Sperry, Nov 16 '18 at 22:28
Duplicate: https://stackoverflow.com/questions/630950/pure-virtual-destructor-in-c. Doesn't error with clang. — juanchopanza, Nov 16 '18 at 22:34

score 3 · Accepted Answer · answered Nov 16 '18 at 22:32

3

Whereas, clang generates warning for:

class A {
public:
    virtual ~A() {}
    virtual void foo() = 0;
};

using = default doesn't trigger it.

class A {
public:
    virtual ~A() = default;
    virtual void foo() = 0;
};

Even if both are valid.

Demo

answered Nov 16 '18 at 22:32

Jarod42

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Virtual destructor for pure abstract base classes

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