[Bug c++/37112] New: nested inherited class can't access protected members of base class

[darkwingz at yahoo dot com]

The following code fails to compile:

class A {
protected:
int i;
};

class B {
class C : public A {
public:
void foo(A a) { 
a.i = 1;
}
};
};

int main()
{

}

nest2.cpp: In member function 'void B::C::foo(A)':
nest2.cpp:3: error: 'int A::i' is protected
nest2.cpp:10: error: within this context

I can't find anything in the standard that says this should be invalid, but
perhaps I missed it. Thanks for your time and efforts.


-- 
   Summary: nested inherited class can't access protected members of
base class
   Product: gcc
   Version: 4.2.2
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
    ReportedBy: darkwingz at yahoo dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37112

[Bug c++/37112] nested inherited class can't access protected members of base class

[darkwingz at yahoo dot com]

--- Comment #2 from darkwingz at yahoo dot com  2008-08-13 15:57 ---
Thanks for your reply. I think I would have seen this had I tried testing it
without the nesting. I tried to compile the following code:

class A {
protected:
int i;
};

class B : public A {
public:
void foo(A *a) {
a->i = 1;
}
};

And it also did not work. However, if I change the parameter of foo() to a B,
then it works. I guess this is to prevent a child class from modifying an
instance of type parent, and not type child. It's ok to modify something
protected if it's your type, but by making the parameter the type of the parent
you can't be sure it's the same child type. (Well, you can with dynamic_cast,
but it wouldn't make sense to allow it.) 

Thanks for the food for thought. I'll cancel the bug.


-- 

darkwingz at yahoo dot com changed:

   What|Removed |Added

 Status|UNCONFIRMED |RESOLVED
 Resolution||INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37112