[C++-sig] Dynamic Cast failed over multiple modules

[Holger Brandsmeier]

Dear List,

when I use dynamic cast from two boost modules on a class with "vague
linkage", in my real use case a template in the simplified example I
show you a class which is declared inline, then the dynamic cast fails
in the second module.

So when I call the code from python from the first module (in which
the Vertex object has been created), then the dynamic cast succeeds:

"calling performTest(m) ...
I am a Vertex"

but when I do the same from the other module, then I get

"calling performTest2(m) ...
dynamic cast failed, I got the object:
I am a Vertex"

I attached a very simple example in the files:
  bugDynamicCastSimplified.h (declares the Classes VerboseObject,
Vertex and Mesh)
  bugDynamicCastPy.cpp (first boost module)
  bugDynamicCast2Py.cpp (second boost module)

The problem dissapears without the vague linkage, e.g. when you define
REMOVE_INLINE_DEFINITION in the code. This is not a very nice  option
for me, as in my real use case Vertex is a template, and this would
force me to initialize it for each type.

My gcc is:
> g++ --version
g++ (Gentoo 4.4.5 p1.2, pie-0.4.5) 4.4.5

And I am building the project with cmake (not boost). I read the FAQ
entry at http://gcc.gnu.org/faq.html#dso and added "-Wl,-E" to
CMAKE_SHARED_LINKER_FLAGS. About the RTLD_GLOBAL flag for dlopen, I
don't know how python handles this.

Do you have any ideas how to solve this? Or is this simply not
possible with python?

-Holger
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