[Bug c++/31336] New: template friends and Koenig lookup

["andrew dot olson at hughes dot net" <gcc-bugzilla at gcc dot gnu dot org>]

Koenig lookup doesn't seem to work properly when dealing with template friends
defined within a class.  Friends defined within the definition of a class
shouldn't be visible to the enclosing namespace, and should only be able to be
found via Koenig lookup.  I see that this appears to work as expected for
normal friends, but GCC still appears make the name visible for template
friends.

I think that this behaviour is incorrect, but could I be missing something? 
The Comeau C++ with EDG front end seems to agree with my reading of the spec,
but then its possible that its behaviour is incorrect instead.

In the following test program, I think that tests #5 and #7 should fail to
compile, but do not.  Neither bar(int, int) and bar(Foo, int) contain an
associated class to class Bar and therefore should not be found.

Thanks!

Andy



#include <iostream>

struct Bar;

struct Foo
{
  Foo() { }
  Foo(const Bar &src) { std::cout << "Bar->Foo" << std::endl; }
  Foo(int src) { std::cout << "int->Foo" << std::endl; }

  friend void foo(const Foo &a, int b)
  {
    std::cout << "Foo " << b << std::endl;
  }
};

struct Bar
{
  operator int() { return(9); } // for test 9

  template<typename A, typename B>
  friend void bar(const A &a, B b)
  {
    std::cout << "Bar " << b << std::endl;
  }
};

int main(int argc, char *argv[])
{
  Foo f;
  Bar b;

  //foo(1, 0);      // #0 - EDG, MSVC 8, GCC 4.1.2 no yes via conversion ctor
  foo((Foo)1, 1); // #1 ok via conv ctor
  foo(f, 2);      // #2 ok
  //foo(b, 3);      // #3 EDG no, GCC 4.1.2 no,  MSVC 8 yes via conv ctor 
  foo((Foo)b, 4); // #4 ok via conv ctor

  bar(1, 5);   // #5 EDG, MSVC 8 no,  GCC 4.1.2 yes
  bar(b, 6);   // #6 ok
  bar(f, 7);   // #7 EDG no,  MSVC 8, GCC 4.1.2 yes
  bar(b, "8"); // #8 ok
  bar(f, b);   // #9 ok

  return(0);
}


-- 
           Summary: template friends and Koenig lookup
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: andrew dot olson at hughes dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31336