[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.

-- 
   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 17:29 
---
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

[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  2005-01-28 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.

-- 
   What|Removed |Added

  Component|libstdc++   |c++


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