[Bug c++/46626] New: [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[Bug c++/46626] New: [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

           Summary: [4.6 Regression] simple use of virtual methods causes
                    pure virtual method call in c++0x mode
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz
            Target: x86_64-pc-linux-gnu


Created attachment 22501
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22501
reduced testcase

$ g++ -std=c++0x testcase.C
$ ./a.out 
pure virtual method called
terminate called without an active exception
Aborted

Tested revisions
r167054 - fail
r167002 - fail
r165699 - OK

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-11-23 19:37:08 UTC ---
related to PR 46526 ?

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2010.11.23 19:57:55
                 CC|                            |jason at redhat dot com
   Target Milestone|---                         |4.6.0
     Ever Confirmed|0                           |1

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2010-11-23 19:57:55 UTC ---
It is caused by revision 166167:

http://gcc.gnu.org/ml/gcc-cvs/2010-11/msg00053.html

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> 2010-11-23 19:58:33 UTC ---
(In reply to comment #1)
> related to PR 46526 ?

Revision 167049 still fails.

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

--- Comment #4 from Zdenek Sojka <zsojka at seznam dot cz> 2010-12-08 00:43:03 UTC ---
This seems to cause FAILs in libstdc++ testsuite with -O0, for example:
$ g++ 42819.ii -std=gnu++0x
$ ./a.out
terminate called after throwing an instance of 'std::system_error'
  what():  Unknown error 18446744073709551615
Aborted

(all failures I encountered are from 30_threads)

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-12-08 02:07:31 UTC ---
Most of the 30_threads tests will abort without -pthread

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

--- Comment #6 from Zdenek Sojka <zsojka at seznam dot cz> 2010-12-08 12:39:59 UTC ---
Thank you, I did my flag reduction wrongly. It seems using of precompiled
headers sometimes causes wrong code, but it's unrelated to this PR.

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |jakub at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-12-23 12:34:40 UTC ---
Created attachment 22846
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22846
gcc46-pr46626.patch

Untested fix.  The problem seems to be that the B::B() ctor body, which is
constexpr (and g++ generated) has a CLEANUP_STMT in it, and
build_data_member_initialization ignores CLEANUP_STMT, which means the setting
of vtable pointer to _ZTV1B + 16 is ignored, thus it stays to be _ZTV1A + 16.

The attached patch handles CLEANUP_BODY of CLEANUP_STMT by recursing into it.

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[roman at binarylife dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

--- Comment #8 from Roman Kononov <roman at binarylife dot net> 2010-12-25 01:49:05 UTC ---
With the patch applied to r168236:

$ cat test.cpp 
struct X {
    virtual int& x(int&)=0;
    virtual ~X() {}
};

struct Y {
    virtual int& y(int&)=0;
    virtual ~Y() {}
};

struct Z: X, Y {
    int& x(int&);
    int& y(int&);
};

void func() {
    Z z;
}

$ g++ -c -std=c++0x test.cpp
test.cpp: In function 'void func()':
test.cpp:17:7:   in constexpr expansion of 'z.Z::Z()'
test.cpp:17:7: internal compiler error: in cxx_eval_bare_aggregate, at
cp/semantics.c:6352
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

Without the patch, with the same test.cpp:

$ g++ -c -std=c++0x test.cpp; echo $?
0

Without the patch, with slightly different test1.cpp:

0 rk@wata:~/tmp/qqq>cat test1.cpp 
struct X {
    virtual int& x(int&)=0;
//  virtual ~X() {}
};

struct Y {
    virtual int& y(int&)=0;
//  virtual ~Y() {}
};

struct Z: X, Y {
    int& x(int&);
    int& y(int&);
};

void func() {
    Z z;
}

0 rk@wata:~/tmp/qqq>g++ -c -std=c++0x test1.cpp
test1.cpp: In function 'void func()':
test1.cpp:17:7:   in constexpr expansion of 'z.Z::Z()'
test1.cpp:17:7: internal compiler error: in cxx_eval_bare_aggregate, at
cp/semantics.c:6338
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-12-27 12:54:34 UTC ---
Author: jakub
Date: Mon Dec 27 12:54:30 2010
New Revision: 168271

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=168271
Log:
    PR c++/46626
    * semantics.c (build_data_member_initialization): For CLEANUP_STMT
    recurse into CLEANUP_BODY.

    * g++.dg/cpp0x/constexpr-base4.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-base4.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/semantics.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/46626] [4.6 Regression] simple use of virtual methods causes pure virtual method call in c++0x mode

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46626

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-12-27 13:15:24 UTC ---
I see the ICE with the second testcase from #c8 back till r166167, therefore
please file it as a separate bugreport, it is not related to this one.