CODEWITHSUNDEEP
c++compiler-warningsiccvirtual-destructor
Flusslauf
Flusslauf

Reputation: 102

Intel C++ compiler and Wnon-virtual-dtor flag gives (wrong?) warning

I was trying to compile some code of mine which, in g++ (with the --Wnon-virtual-dtor Flag) compiled just fine. Also, my IDE and clang-tidy didn't warn me (I see that this might be false of course).

When I tried to compile the same code with Intel's icpc (actually this one icpc (ICC) 19.1.2.254 20200623) I got a warning which I was now able to track down - I'm wondering whether I'm somehow at fault or whether that warning is actually not correct in my case.

I wrote a somewhat minimal example of my class hierarchy:

template<typename T>
class B {
        public:
                B() = default;
                virtual ~B() = default;
};

template<typename T>
class C : public B<T> {
        public:
                C() = default;
                ~C() override = default;

                virtual int foo() { return 0; };
};

template<typename T>
class D : public C<T> {
        public:
                D() = default;
                ~D() override = default;
                int foo() override { return 1; };
};


int main() {
        return 0;
}

When compiling this with icpc -Wnon-virtual-dtor foo.cpp I get the following warning:

foo.cpp(15): warning #2026: Effective C++ Item 14 Make sure base classes C have virtual destructors
  };
   ^

One can get rid of that by explicitly stating that the destructor in C is virtual (so virtual ~C() override = default;).

Note, that also getting rid of the template lets the code compile without any warning.

For last - also getting rid of the foo member function will let the code compile without warning.

So yeah - my question is: is this a "bug" in icpc or did I do something wrong?

I was quite unable to find anything useful on that warning #2026 really.

Thanks in advance, Flusslauf

Upvotes: 0

Views: 251

Answers (1)

Flusslauf
Flusslauf

Reputation: 102

Ok, so after also posting this question on the Intel forum - seems to be (a very much non critical) bug in the compiler - the workaround would be writing both, virtual and override.

This is discouraged by the item C.128 in the cpp core guidelines (same link as in the comments) but not problematic.

Upvotes: 1

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