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.
Created attachment 8032 [details] Example program that demonstrates the bug
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.
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).
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
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.
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.