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Date: Mon, 04 Jun 2007 12:01:00 -0000
Subject: [Bug c++/32204]  New: friend from global namespace in template class ignored
Message-ID: <bug-32204-3000@http.gcc.gnu.org/bugzilla/>
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From: "klaus dot kretschel at dlr dot de" <gcc-bugzilla@gcc.gnu.org>
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First: I apologize if this report is missing something but I did not find
enough information in the guidelines to be more accurate. Furthermore, I have
only gcc 4.1.2 prerelease available (from Suse Linux 10.2), so I will be glad
if somebody tells me the bug has been fixed in a later version.

The bug is related to 8355 and 9230, but I guess it's different.

The following program does not compile; depending on the kind of invocation of
'f' 3 different errors occur (where the messages of 1 and 3 contradict to each
other, see below):

namespace A { template < class PIX > class B; }

void f(A::B<int>&);

template < class PIX > class A::B {
  friend void ::f(A::B<int>&);
  PIX z;
};

void f(A::B<int>& i) { int a = i.z; }

int main() {
  A::B<int> b;
  f(b);         // 1. error: f is ambiguous (no, there is no 2nd declaration!)
  ::f(b);       // 2. error: z is private (yes, but 'f' is a friend)
  A::f(b);      // 3. error: f is not a member of A (of course)
}

The only invocation that should yield an error is no. 3. No. 2 should
definitely work, and I guess the double colon for the global namespace should
be unnecessary anywhere.

No error occurs if I transfer 'f' from the global namespace to another one (C):

namespace A { template < class PIX > class B; }

namespace C { void f(A::B<int>&); }

template < class PIX > class A::B {
  friend void C::f(A::B<int>&);
  PIX z;
};

void C::f(A::B<int>& i) { int a = i.z; }

int main() {
  A::B<int> b;
  C::f(b);           // OK
  using namespace C;
  f(b);              // OK
}

Another work-around is to make 'f' an template function.


-- 
           Summary: friend from global namespace in template class ignored
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: klaus dot kretschel at dlr dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32204