[Bug c++/45880] Template-Methode in Shared Object not resolved when compiled with -O2

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45880

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-10-04 
16:34:21 UTC ---
We need a self-contained testcase that reproduces the problem.

I suspect you just need an explicit instantiation of that template function in
the shared library, if nothing instantiates it explicitly then the symbol won't
be defined.

For your broken minimal example that would be done like this:

template void TestTemplateOpt::printMessage(std::string);