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From: "jeffrey.hellrung at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/53421] New: __attribute((__may_alias__)) prevents taking address of conversion operator member function
Date: Sat, 19 May 2012 21:26:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D53421

             Bug #: 53421
           Summary: __attribute((__may_alias__)) prevents taking address
                    of conversion operator member function
    Classification: Unclassified
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: jeffrey.hellrung@gmail.com


Created attachment 27446
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=3D27446
source file exhibiting the bug when compiled

Compiling attached main.cpp gives the following error:

jeffrey@ubuntu:~/scratch$ g++ -o scratch main.cpp
main.cpp: In function =E2=80=98int main(int, char**)=E2=80=99:
main.cpp:21:6: error: =E2=80=98operator Y<X>&=E2=80=99 is not a member of =
=E2=80=98X=E2=80=99

However, no error occurs with any of the following changes:
(a) Removing the __attribute__((__may_alias__)) (commenting in line 3 and
commenting out line 4).
(b) Removing the implementation (line 8) or using a throwing implementation
(line 9) rather than the present implementation (line 10).
(c) Replacing the conversion operator with a regular member function
(commenting out lines 10,21 and commenting in lines 11,22 or 12,22.

Further investigation reveals a possibly related error. One can define the
function out-of-line (commenting in lines 8,16 and commenting out line 10) =
with
no error, as long as line 15 remains commented out; additionally commenting=
 in
line 15 gives the following error:

jeffrey@ubuntu:~/scratch$ g++ -o scratch main.cpp
main.cpp:16:20: error: no =E2=80=98X::operator Y<X>&()=E2=80=99 member func=
tion declared in
class =E2=80=98X=E2=80=99

This error still appears if one uses a throwing implementation (like in (b)=
) or
replaces the conversion operator with a regular member function (like in (c=
)),
but no error occurs with the removal of the __attribute__((__may_alias__)) =
(as
in (a)).