c++/603: Problem with Equally-Named Friend- and Member-Functions

[kfischer at iiic dot ethz dot ch]

>Number:         603
>Category:       c++
>Synopsis:       Problem with Equally-Named Friend- and Member-Functions
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Wed Oct 04 10:16:00 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     Kaspar Fischer
>Release:        gcc version 2.95.2 19991024 (release)
>Organization:
>Environment:
Linux 2.2.17 on PowerPC (Apple PowerBook G3 Wallstreet)
>Description:
gcc 2.95.2 refuses to compile the small attached program:

        [janosch@localhost test]$ g++ test2.c -o test
        test2.c: In instantiation of `A<int>':
        test2.c:17:   instantiated from here
        test2.c:9: invalid use of undefined type `struct A<int>'
        test2.c:11: forward declaration of `struct A<int>'

However, if I comment out line 10, everything works fine.
(Having posted the code to comp.lang.c++.moderated, someone
reported that Borland C++ compiles the code.)

PS.  The 'same' program without templates works fine:

class A;
A f(const A&,const A&);

struct A {
  friend A f(const A&,const A&);
  const A f() const { return A(); }
};

A f(const A& a,const A&) { return a; }

int main(int argc,char **argv) {
  A a1,a2;
  A a = f(a1,a2);
  a = a1.f();
  return 0;
}

Thanks a lot for your efforts!
Kaspar
>How-To-Repeat:
template<typename D>
struct A;

template<typename D>
A<D> f(const A<D>&,const A<D>&);

template<typename D>
struct A {
  friend A<D> f<D>(const A<D>&,const A<D>&); /* line 9 */
  const A<D> f() const { return A(); } /* line 10 */
};

template<typename D>
A<D> f(const A<D>& a,const A<D>&) { return a; }

int main(int argc,char **argv) {
  A<int> a1,a2; /* line 17 */
  A<int> a = f(a1,a2);
  return 0;
}
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: application/octet-stream; name="test2.c"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="test2.c"

dGVtcGxhdGU8dHlwZW5hbWUgRD4Kc3RydWN0IEE7Cgp0ZW1wbGF0ZTx0eXBlbmFtZSBEPgpBPEQ+
IGYoY29uc3QgQTxEPiYsY29uc3QgQTxEPiYpOwoKdGVtcGxhdGU8dHlwZW5hbWUgRD4Kc3RydWN0
IEEgewogIGZyaWVuZCBBPEQ+IGY8RD4oY29uc3QgQTxEPiYsY29uc3QgQTxEPiYpOyAvKiBsaW5l
IDkgKi8KICBjb25zdCBBPEQ+IGYoKSBjb25zdCB7IHJldHVybiBBKCk7IH0gLyogbGluZSAxMCAq
Lwp9OwoKdGVtcGxhdGU8dHlwZW5hbWUgRD4KQTxEPiBmKGNvbnN0IEE8RD4mIGEsY29uc3QgQTxE
PiYpIHsgcmV0dXJuIGE7IH0KCmludCBtYWluKGludCBhcmdjLGNoYXIgKiphcmd2KSB7CiAgQTxp
bnQ+IGExLGEyOyAvKiBsaW5lIDE3ICovCiAgQTxpbnQ+IGEgPSBmKGExLGEyKTsKICByZXR1cm4g
MDsKfQoK