http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59930
Bug ID: 59930
Summary: template friend declarations, namespaces, and explicit
instantiations don't mix
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: luto at mit dot edu
namespace NS {
template<typename T>
class Holder
{
private:
void func();
template<typename>
friend class User;
};
template class Holder<long>;
template<typename T>
class User
{
public:
void method() const
{
Holder<T> x;
x.func();
}
};
} // namespace
// This one is okay, oddly.
// template class NS::Holder<long>;
void Foo()
{
NS::User<long> decl;
decl.method();
}
says (in trunk r207012):
$ g++-trunk -Wall -c template_friend.cc
template_friend.cc: In instantiation of ‘void NS::User<T>::method() const [with
T = long int]’:
template_friend.cc:34:14: required from here
template_friend.cc:7:7: error: ‘void NS::Holder<T>::func() [with T = long int]’
is private
void func();
^
template_friend.cc:22:3: error: within this context
x.func();
^
The 4.8 branch can't compile this either, but clang is okay with it.
Oddly, removing the namespace, removing the explicit instantiation, or moving
the explicit instantiation outside the namespace causes g++ to accept this
code.
