[Bug c++/45383] New: [g++ >= 4.5 ] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[Bug c++/45383] New: [g++ >= 4.5 ] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[seysayux at gmail dot com]

Consider this code:
--------------------
#include <iostream>
struct null {
    null() {}
    template<class T>
    operator T*() const {
        return 0;
    }

    template<class C, class T>
    operator T C::*() const {
        return 0;
    }
private:
    null(const null&);
    null& operator=(const null&);
    void operator&() const;
};

static struct null null;

int main() {
    int* ptr = null;
    std::cout << (ptr == null) << ", " << (ptr != null);
    return 0;
}
--------------------------------
This compiles and gives the expected output ("true, false") on the following
platforms:

http://codepad.org (GCC 4.1, Linux)
Ubuntu 9.10, GCC 4.3
Ubuntu 10.04, GCC 4.4
Mac OS X 10.6, GCC 4.2
Mac OS X 10.6, GCC 4.4
Cygwin, GCC 4.3
Cygwin, GCC 4.4
Unknown Linux variant, Clang 2.8 (trunk 111679) (the "clang" bot on
irc.freenode.net)

However, I get following error on these platforms
-------------
error: no match for 'operator==' in 'ptr == null'
-------------
Cygwin, GCC 4.5
Ubuntu 10.04, GCC 4.5
Unknown Linux variant, GCC 4.6.0 20100507 (the "geordi" bot on
irc.freenode.net)

The people in the irc.freenode.net/##c++ channel confirm that this is indeed
valid C++ code and therefore a bug in GCC.

I do not have ready access to some of these systems (anymore), so I can not say
with certainity what their host, target, or build triplets are.


-- 
           Summary: [g++ >= 4.5 ] Implicit conversion to pointer does no
                    longer automatically generate operator== and operator!=.
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: seysayux at gmail dot com
 GCC build triplet: (many, read below)
  GCC host triplet: (many, read below)
GCC target triplet: (many, read below)


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[redi at gcc dot gnu dot org]

------- Comment #1 from redi at gcc dot gnu dot org  2010-08-23 13:17 -------
The summary seems backwards: the conversion shouldn't generate operator==,
instead using operator== should trigger the conversion, but fails to when the
conversion operator is a template.

Strangely, adding a non-template conversion operator causes template argument
deduction to succeed, even though the non-template operator isn't used
e.g.

#include <iostream>
struct null {
    null() {}
    template<class T>
    operator T*() const {
        return 0;
    }

    template<class C, class T>
    operator T C::*() const {
        return 0;
    }
private:
    operator double*() const;  // ???
    null(const null&);
    null& operator=(const null&);
    void operator&() const;
};

static struct null null;

int main() {
    int* ptr = null;
    std::cout << (ptr == null) << ", " << (ptr != null);
    return 0;
}


-- 

redi at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
  GCC build triplet|(many, read below)          |
   GCC host triplet|(many, read below)          |
 GCC target triplet|(many, read below)          |
           Keywords|                            |rejects-valid
   Last reconfirmed|0000-00-00 00:00:00         |2010-08-23 13:17:12
               date|                            |
            Summary|[g++ >= 4.5 ] Implicit      |[4.5/4.6 Regression]
                   |conversion to pointer does  |Implicit conversion to
                   |no longer automatically     |pointer does no longer
                   |generate operator== and     |automatically generate
                   |operator!=.                 |operator== and operator!=.


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[hjl dot tools at gmail dot com]

------- Comment #2 from hjl dot tools at gmail dot com  2010-08-23 16:35 -------
It is caused by revision 155415:

http://gcc.gnu.org/ml/gcc-cvs/2009-12/msg00559.html


-- 

hjl dot tools at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dseketel at redhat dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.5.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.5.2                       |4.5.3

--- Comment #7 from Richard Guenther <rguenth at gcc dot gnu.org> 2010-12-16 13:03:46 UTC ---
GCC 4.5.2 is being released, adjusting target milestone.

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

--- Comment #6 from Dodji Seketeli <dodji at gcc dot gnu.org> 2010-11-29 16:31:54 UTC ---
Author: dodji
Date: Mon Nov 29 16:31:40 2010
New Revision: 167250

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=167250
Log:
Fix PR c++/42260 and ensure PR c++/45383 is fixed

gcc/cp/
    c++/42260
    * call.c (add_builtin_candidate): At this point the resulting type
    of an indirection operator should be complete.

gcc/testsuite/
    c++/42260
    c++/45383
    * g++.dg/conversion/cast2.C: New test.
    * g++.dg/conversion/cond4/C: Likewise. Ensures we don't regress on
    PR c++/45383

Added:
    trunk/gcc/testsuite/g++.dg/conversion/cast2.C
    trunk/gcc/testsuite/g++.dg/conversion/cond4.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/call.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

--- Comment #5 from Dodji Seketeli <dodji at gcc dot gnu.org> 2010-11-29 16:31:07 UTC ---
Author: dodji
Date: Mon Nov 29 16:30:54 2010
New Revision: 167248

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=167248
Log:
Fix PR c++/45383

Reverting the fix for PR c++/42260 fixes c++/45383.
This reverts commit r155415.

gcc/cp/
    Reverted patch for PR c++/42260
    * cp-tree.h (lookup_conversions): Reverted "Add new bool parameter to
    declarationE."
    * search.c (lookup_conversion): Reverted "Use new bool parameter in
    definition".
    * call.c (add_builtin_candidates): Reverted "Don't lookup template
          conversion"
    (convert_class_to_reference, build_user_type_conversion_1,
     build_op_call): Reverted "Adjust".
    * cvt.c (build_expr_type_conversion): Reverted "Likewise".

gcc/testsuite/
    Reverted patch for PR c++/42260
    * conversion/cast2.C: Reverted New test.

Removed:
    trunk/gcc/testsuite/g++.dg/conversion/cast2.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/call.c
    trunk/gcc/cp/cp-tree.h
    trunk/gcc/cp/cvt.c
    trunk/gcc/cp/search.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[dodji at seketeli dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

--- Comment #4 from dodji at seketeli dot org <dodji at seketeli dot org> 2010-11-11 08:24:20 UTC ---
A candidate fix has been proposed at
http://gcc.gnu.org/ml/gcc-patches/2010-11/msg01129.html

Re: [Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[Dodji Seketeli]

A candidate fix has been proposed at http://gcc.gnu.org/ml/gcc-patches/2010-11/msg01129.html

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

Dodji Seketeli <dodji at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|dseketel at redhat dot com  |
         AssignedTo|unassigned at gcc dot       |dodji at gcc dot gnu.org
                   |gnu.org                     |

[Bug c++/45383] [4.5/4.6 Regression] Implicit conversion to pointer does no longer automatically generate operator== and operator!=.

[number.cruncher at ntlworld dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45383

Simon <number.cruncher at ntlworld dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |number.cruncher at ntlworld
                   |                            |dot com

--- Comment #3 from Simon <number.cruncher at ntlworld dot com> 2010-11-08 13:46:44 UTC ---
I'd just like to confirm this bug on Fedora 14 (gcc (GCC) 4.5.1 20100924) which
is currently preventing me from compiling a large 3D graphics commercial
library.