Disable warning about explicitly initializing base constructor inside copy constructor of derived class

Question

I\'m using g++ version 4.2.1 with -Wextra enabled. I\'m including a header from a library, and I keep getting the following warning about a class in the library, which is enable

Answer 1

According to http://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html (search for Wextra) that is an inherent part of -Wextra and can't be disabled separately (e.g. it isn't listed separately by its own -W option).

It looks like the best you can do is either isolate the use of the library to one file on which you disable -Wextra or don't use -Wextra at all and individually enable all its components (from that link).

Answer 2

If it's not a real problem, and you can't change the library (I guess you can't or you'd have done so), you can disable warnings temporarily using the GCC diagnostic pragma.

Answer 3

Given:

class BaseClass
{
public:
    BaseClass();
    BaseClass(const BaseClass&);
};

class DerivedClass : public BaseClass
{
public:
    DerivedClass(const DerivedClass&);
};

This copy constructor:

DerivedClass::DerivedClass(const DerivedClass& obj)
  // warning: no BaseClass initializer!
{
}

Really means the same as:

DerivedClass::DerivedClass(const DerivedClass& obj)
  // Default construct the base:
  : BaseClass()
{
}

You can put in a default-constructor initializer like the above if that's really what you mean, and the warning will go away. But the compiler is suggesting that you might actually want this instead:

DerivedClass::DerivedClass(const DerivedClass& obj)
  // Copy construct the base:
  : BaseClass(obj)
{
}