https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86876
Bug ID: 86876
Summary: friend typedef'ed class in template class can not
compile
Product: gcc
Version: 7.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: rockeet at gmail dot com
Target Milestone: ---
// code:
#include <stdio.h>
template<class T>
struct A {
template<class U>
struct X {
void foo(U* p) { printf("p->a = %d\n", p->a); }
};
};
template<class T>
struct B {
typedef typename A<T>::template X<B<T> > X;
// friend typename X; // g++ fail
friend typename B::X; // g++ ok
private:
int a = 1234;
};
int main() {
B<int> a;
B<int>::X().foo(&a);
return 0;
}
/*
Compile error:
template_friend.cpp:12:21: error: expected nested-name-specifier before ‘X’
friend typename X; // g++ fail
^
template_friend.cpp:12:21: error: ‘X’ is neither function nor member function;
cannot be declared friend
template_friend.cpp:12:21: error: ‘int B<T>::X’ conflicts with a previous
declaration
template_friend.cpp:11:43: note: previous declaration ‘typedef typename
A<T>::X<B<T> > B<T>::X’
typedef typename A<T>::template X<B<T> > X;
^
template_friend.cpp: In instantiation of ‘void A<T>::X<U>::foo(U*) [with U =
B<int>; T = int]’:
template_friend.cpp:19:20: required from here
template_friend.cpp:6:45: error: ‘int B<int>::a’ is private within this context
void foo(U* p) { printf("p->a = %d\n", p->a); }
~~~^
template_friend.cpp:15:10: note: declared private here
int a = 1234;
^~~~
*/
