using g++, how to deprecate virtual class member functions

I seem to be having trouble getting deprecated warnings to print out, for functions declared as virtual. I'm using "g++ (GCC) 4.1.1 20061011 (Red Hat 4.1.1-30)." My research shows that there might be problems in gcc 4.x regarding deprecating pure virtual functions(i.e. class bueller{ virtual int cameron()=0;};), but not... I'd guess you'd call them regular... virtual functions. Just so we're on the same page...

foo.h

class Foo
{
  void Foo_A() __attribute__((deprecated)); //non-virtual
  virtual void Foo_B() __attribute__((deprecated)); //virtual
  virtual void Foo_C() __attribute__((deprecated)) = 0; //pure virtual
};

Say I compiled this, an foo.cpp file and some main.cpp file using g++.

1)Anything that uses Foo_A() will indeed show a warning.

2)Anything that uses Foo_B() does NOT show a warning.

3)Anything that inherits Foo, implements Foo_C and then uses it does not show warning.

Number 1: it works, no problem.

Number 3: seems like a known bug/feature.. whatever..

There seems to be no explination for #2 however. Perhaps it's 开发者_开发百科tied up in #3, although nothing I've found makes mention of it.

Anyone know if I'm missing anything here regarding regular virtual class member functions that I want to deprecate?

BTW: -Wno-deprecate is NOT turned on in my makefiles.

Given this program:

struct Foo
{
  virtual void Foo_B() __attribute__((deprecated)); //virtual
};

struct DerivedFoo : public Foo
{
};


int main()
{
  DerivedFoo d;
  d.Foo_B();
  Foo &f = d;
  f.Foo_B();
}
void Foo::Foo_B() {}

On CentOS 5.2 (gcc version 4.1.2 20080704 (Red Hat 4.1.2-44)), I get the same output that you describe:

g++     deprecate.cc   -o deprecate
deprecate.cc: In function ‘int main()’:
deprecate.cc:14: warning: ‘Foo_B’ is deprecated (declared at deprecate.cc:3)

But, on Ubuntu 10.04.1 (gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5)), I get the output that you expect:

g++     deprecate.cc   -o deprecate
deprecate.cc: In function ‘int main()’:
deprecate.cc:14: warning: ‘virtual void Foo::Foo_B()’ is deprecated (declared at deprecate.cc:3)
deprecate.cc:16: warning: ‘virtual void Foo::Foo_B()’ is deprecated (declared at deprecate.cc:3)

So, I'm guessing it was a compiler bug that got fixed.

Do you call Foo_B()/Foo_C() through a Foo pointer/reference, or a derived class? If you use a derived class it seems that you have to mark the methods deprecated in it as well, or you get the behaviour you describe.

Google shows an old discussion on this topic at a Debian list. But nothing more recent comes up on this topic. Try asking on the distribution's (RedHat's, in this case) lists.