The code:
template<typename T>
struct b1 {
protected:
void inc() {}
T* dummy;
};
template<typename T, template<typename>class F>
struct b2 {
void f() {
F<T>* s = static_cast<F<T>*>(this);
s->inc();
}
};
template<typename T>
struct G : public b1<T>, public b2<T, G> {
};
int main() {
G<int> g;
g.f();
}
gets you:
~/ootbc/members/src$ g++ foo.cc
foo.cc: In member function `void b2<T, F>::f() [with T = int, F = G]':
foo.cc:22: instantiated from here
foo.cc:4: error: `void b1<T>::inc() [with T = int]' is protected
foo.cc:11: error: within this context
The access to "inc" is "s->inc()". "s" is a "F<T>", which after parameter
substitution is a "G<int>". "b2<T, G>" is a public base of G, which after
substitution means that "b2<int, G>" is a public base of "G<int>" and so is
also
a public base of "s". Hence the protected member "b2<int, G>::inc" should be
visible via "s", but is not.
Ivan
--
Summary: Static_cast loses access to protected
Product: gcc
Version: 3.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: igodard at pacbell dot net
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24592
