[Bug libstdc++/19567] New: dynamic_cast failure in dlopen-ed shared object

[Bug libstdc++/19567] New: dynamic_cast failure in dlopen-ed shared object

[daveregs at rsaisp dot com]

Please note this is not a duplicate of #4993, because I am using RTLD_GLOBAL and
-Wl,-E.

This test project demonstatrates a problem when using dynamic_cast from inside a
shared object to attempt to convert a base class (interface) to a derived class
(another interface) whose definitions are in header files shared between the
application and the shared object.

When casting from a base class to the derived class from inside the main
executable, dynamic_cast works as expected and returns a non null pointer. 
However, from inside of the dlopen-ed shared library, the dynamic_cast function
incorrectly returns zero.

Attachment will follow.

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           Summary: dynamic_cast failure in dlopen-ed shared object
           Product: gcc
           Version: 3.4.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: daveregs at rsaisp dot com
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19567

[Bug libstdc++/19567] dynamic_cast failure in dlopen-ed shared object

[daveregs at rsaisp dot com]

------- Additional Comments From daveregs at rsaisp dot com  2005-01-21 17:30 -------
Tested on fedora core 2 and 3, results are the same.
more info:  fc2: gcc version 3.3.3 20040412

Works on windows 3.4.2 (mingw-special) most likely because of the lack of
support for weak symbols.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19567

[Bug libstdc++/19567] dynamic_cast failure in dlopen-ed shared object

[daveregs at rsaisp dot com]

------- Additional Comments From daveregs at rsaisp dot com  2005-01-21 17:29 -------
Created an attachment (id=8032)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=8032&action=view)
Example program that demonstrates the bug


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19567

[Bug libstdc++/19567] dynamic_cast failure in dlopen-ed shared object

[chris at bubblescope dot net]

------- Additional Comments From chris at bubblescope dot net  2005-01-28 14:53 -------
I don't think this bug has anything to do with libstdc++ (which over covers
errors in the c++ standard library). I would suggest changing the Component to
c++, which I suspect a closer match for where the bug lives (although I'm not
certain I will admit).

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19567

[Bug libstdc++/19567] dynamic_cast failure in dlopen-ed shared object

[daveregs at rsaisp dot com]

------- Additional Comments From daveregs at rsaisp dot com  2005-01-28 15:10 -------
Hi Chris,

I beleive that this problem may be related to the typeinfo header or other 
related headers that are involved with RTTI.

I have also refered to an older bug that involved this same problem which was 
posted under libstdc++ and appeared to have been resolved in this category:  
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=4292

However, I could be wrong, so if you are positive I have this in the wrong 
category I will move it.

Thank you,
- Dave

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19567

[Bug c++/19567] dynamic_cast failure in dlopen-ed shared object

[daveregs at rsaisp dot com]

------- Additional Comments From daveregs at rsaisp dot com  2005-02-02 03:28 -------
This is becoming a real showstopper for me, so I am changing the component to
C++ in the hopes that it is a closer match and this bug will be looked at.

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           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|libstdc++                   |c++


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19567

[Bug c++/19567] dynamic_cast failure in dlopen-ed shared object

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-02 03:52 -------
You messed up you used -W1, not -Wl which is different.

you need to use l as in the lowercase L.
I changed the Makefile to use -Wl,-E and it worked.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19567