[Bug c++/35067] New: [4.2 Regression] multiple definition of virtual thunk

[Bug c++/35067] New: [4.2 Regression] multiple definition of virtual thunk

[vincent dot riviere at freesbee dot fr]

C++ programs using virtual inheritance cannot be linked due to multiple
definitions of thunk symbols.

$ cat c.h
class B
{
public:
        virtual ~B() { }
};

class C : virtual public B
{

};

$ cat f1.cpp 
#include "c.h"

C c1;

main() { }

$ cat f2.cpp 
#include "c.h"

C c2;

$ g++ f1.cpp f2.cpp -nostartfiles
/tmp/ccU01avI.o:/tmp/ccU01avI.o:(.text+0x6c): multiple definition of `virtual
thunk to C::~C()'
/tmp/ccwZV0B9.o:/tmp/ccwZV0B9.o:(.text+0x90): first defined here
/tmp/ccU01avI.o:/tmp/ccU01avI.o:(.text+0x122): multiple definition of `virtual
thunk to C::~C()'
/tmp/ccwZV0B9.o:/tmp/ccwZV0B9.o:(.text+0x146): first defined here

Note: I use -nostartfiles because crt0.o is not available in my test
environment.

This is a regression.
The same testcase has no problem with GCC 4.1.2


-- 
           Summary: [4.2 Regression] multiple definition of virtual thunk
           Product: gcc
           Version: 4.2.3
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: vincent dot riviere at freesbee dot fr
GCC target triplet: i386-netbsd


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2 Regression] multiple definition of virtual thunk

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2008-02-03 22:35 -------
The virtual thunk should be link once in this case.  Can you attach the
assembly files?  Also how did you configure GCC?


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|major                       |normal


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2 Regression] multiple definition of virtual thunk

[vincent dot riviere at freesbee dot fr]

------- Comment #2 from vincent dot riviere at freesbee dot fr  2008-02-03 22:57 -------
This problem seems to happen on targets where ASM_WEAKEN_LABEL() is defined,
but MAKE_DECL_ONE_ONLY() is not defined. In that case, the `virtual
thunk to C::~C()' symbol is defined using .globl instead of using .weak (like
it was in 4.1.2).

I made some investigation. The problem may be related to these source files:
gcc/cp/methods.c in function use_thunk()
  if (DECL_ONE_ONLY (function))
    make_decl_one_only (thunk_fndecl);
This code was different in 4.1.2

gcc/varasm.c in function make_decl_one_only()
  if (SUPPORTS_ONE_ONLY)
    {
#ifdef MAKE_DECL_ONE_ONLY
      MAKE_DECL_ONE_ONLY (decl);
#endif
      DECL_ONE_ONLY (decl) = 1;
    }

When MAKE_DECL_ONE_ONLY is not defined, SUPPORTS_ONE_ONLY is set to 0. So
DECL_ONE_ONLY (decl) = 1 is never called.

Thus if the destructor is flagged DECL_ONE_ONLY, the virtual thunk is not
flagged DECL_ONE_ONLY as it should, then it is defined with .globl instead of
.weak


-- 

vincent dot riviere at freesbee dot fr changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |4.2.3
      Known to work|                            |4.1.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2 Regression] multiple definition of virtual thunk

[vincent dot riviere at freesbee dot fr]

------- Comment #3 from vincent dot riviere at freesbee dot fr  2008-02-03 23:02 -------
Created an attachment (id=15090)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15090&action=view)
Output of f1.cpp


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2 Regression] multiple definition of virtual thunk

[vincent dot riviere at freesbee dot fr]

------- Comment #4 from vincent dot riviere at freesbee dot fr  2008-02-03 23:03 -------
Created an attachment (id=15091)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15091&action=view)
Output of f2.cpp

I configured gcc with:
configure --target=i386-netbsd --disable-multilib --disable-nls
--enable-languages="c,c++"


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2 Regression] multiple definition of virtual thunk

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2008-02-04 10:14 -------
Can you please check a recent gcc 4.3 snapshot?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2 Regression] multiple definition of virtual thunk

[vincent dot riviere at freesbee dot fr]

------- Comment #6 from vincent dot riviere at freesbee dot fr  2008-02-04 13:33 -------
Same problem with version 4.3-20080201


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2/4.3 Regression] multiple definition of virtual thunk

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.2 Regression] multiple   |[4.2/4.3 Regression]
                   |definition of virtual thunk |multiple definition of
                   |                            |virtual thunk
   Target Milestone|---                         |4.2.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2/4.3 Regression] multiple definition of virtual thunk

[vincent dot riviere at freesbee dot fr]

------- Comment #7 from vincent dot riviere at freesbee dot fr  2008-02-04 13:38 -------
(In reply to comment #6)
Sorry, I messed up with the versions...
I'm going to check again the version 4.3 right now.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2/4.3 Regression] multiple definition of virtual thunk

[vincent dot riviere at freesbee dot fr]

------- Comment #8 from vincent dot riviere at freesbee dot fr  2008-02-04 14:02 -------
I confirm this problem is still present in GCC 4.3-20080201.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2/4.3 Regression] multiple definition of virtual thunk

[jakub at gcc dot gnu dot org]

------- Comment #9 from jakub at gcc dot gnu dot org  2008-02-05 20:31 -------
This doesn't affect any primary/secondary platforms.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.2/4.3/4.4 Regression] multiple definition of virtual thunk

[jsm28 at gcc dot gnu dot org]

------- Comment #10 from jsm28 at gcc dot gnu dot org  2008-05-19 20:24 -------
4.2.4 is being released, changing milestones to 4.2.5.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.2.4                       |4.2.5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.3/4.4/4.5 Regression] multiple definition of virtual thunk

[jsm28 at gcc dot gnu dot org]

------- Comment #11 from jsm28 at gcc dot gnu dot org  2009-03-31 20:18 -------
Closing 4.2 branch.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.2/4.3/4.4/4.5 Regression]|[4.3/4.4/4.5 Regression]
                   |multiple definition of      |multiple definition of
                   |virtual thunk               |virtual thunk
   Target Milestone|4.2.5                       |4.3.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.3/4.4/4.5 Regression] multiple definition of virtual thunk

[rguenth at gcc dot gnu dot org]

------- Comment #12 from rguenth at gcc dot gnu dot org  2009-08-04 12:28 -------
GCC 4.3.4 is being released, adjusting target milestone.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.3.4                       |4.3.5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.3/4.4/4.5 Regression] multiple definition of virtual thunk

[jason at gcc dot gnu dot org]

-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jason at gcc dot gnu dot org
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-11-03 21:21:25
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.3/4.4/4.5 Regression] multiple definition of virtual thunk

[jason at gcc dot gnu dot org]

------- Comment #13 from jason at gcc dot gnu dot org  2009-11-04 19:56 -------
Subject: Bug 35067

Author: jason
Date: Wed Nov  4 19:55:56 2009
New Revision: 153912

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=153912
Log:
        PR c++/35067
        * method.c (use_thunk): Check DECL_WEAK as well as
        DECL_ONE_ONLY.

Added:
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/abi/thunk5.C
Modified:
    branches/gcc-4_4-branch/gcc/cp/ChangeLog
    branches/gcc-4_4-branch/gcc/cp/method.c
    branches/gcc-4_4-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.3/4.4/4.5 Regression] multiple definition of virtual thunk

[jason at gcc dot gnu dot org]

------- Comment #14 from jason at gcc dot gnu dot org  2009-11-04 20:08 -------
Subject: Bug 35067

Author: jason
Date: Wed Nov  4 20:08:44 2009
New Revision: 153913

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=153913
Log:
        PR c++/35067
        * method.c (use_thunk): Check DECL_WEAK as well as
        DECL_ONE_ONLY.

Added:
    branches/gcc-4_3-branch/gcc/testsuite/g++.dg/abi/thunk5.C
Modified:
    branches/gcc-4_3-branch/gcc/cp/ChangeLog
    branches/gcc-4_3-branch/gcc/cp/method.c
    branches/gcc-4_3-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.3/4.4/4.5 Regression] multiple definition of virtual thunk

[jason at gcc dot gnu dot org]

------- Comment #15 from jason at gcc dot gnu dot org  2009-11-04 20:10 -------
Fixed for 4.3.5, 4.4.3, 4.5.0.  Vincent, can you verify that it works with the
current sources?


-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067

[Bug c++/35067] [4.3/4.4/4.5 Regression] multiple definition of virtual thunk

[vincent dot riviere at freesbee dot fr]

------- Comment #16 from vincent dot riviere at freesbee dot fr  2009-11-04 23:41 -------
Hello, I've just tested with GCC trunk, it seems to be fixed !
Thanks, Jason.


-- 

vincent dot riviere at freesbee dot fr changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067