c++ - class has virtual functions and accessible non-virtual destructor -

i have 2 classes:

class { public:     virtual void somefunction() = 0; };  class b : public { public:     b();     ~b();     void somefunction(); };  b::b() {}  void b::somefunction() {     //  code } 

but g++ errors:

class has virtual functions , accessible non-virtual destructor class b has virtual functions , accessible non-virtual destructor 

i don't have idea error is... somewhere on blogs read it's compiler warning. how can fix problem?

this happens because base class a not have virtual destructor. instance, if had code:

int main() {     a* = new b;     delete a; } 

then delete a call not able call b's destructor because a's isn't virtual. (it leak of b's resources.) can read more virtual destructors here.

add virtual destructor base class , should fine.

class { public:       virtual void somefunction() = 0;     virtual ~a() = 0; }