Re: [LONG] RF{C,D,A,H}: pe-x86 DLLs (shared libstdc++ and others) vs C++ RTTI vs LD

["Dave Korn" <dave dot korn dot cygwin at googlemail dot com>]

Danny Smith wrote:
>
> If I remember correctly,  there were no problems with *user-defined*
> types and TI tables (with above  _GLIBCXX_IMPORT additions).  The
> problems arose from *language-defined*  types with TI tables generated
> in  libsupc++'s tinfo.cc  and tinfo2.cc.  Excluding those 2 objects
> from libstdc++.dll and adding them as statically-linked objects to the
> libstdc++.a  import lib allowed the comdat linkage (linkonce)
> mechanism to work.
>
> Danny

  Thanks Danny.  It looks like libsupc++ has been refactored a bit since
you looked at this?  There's next to nothing in tinfo.o and tinfo2.o:

/gnu/gcc/release/gcc4-4.3.2-2/build/i686-pc-cygwin/libstdc++-v3/libsupc++ $
nm tinfo.o | grep " [TR] " | cut -d' ' -f3 | c++filt
std::type_info::__do_catch(std::type_info const*, void**, unsigned int) const
std::type_info::__do_upcast(__cxxabiv1::__class_type_info const*, void**) const
std::type_info::__is_pointer_p() const
std::type_info::__is_function_p() const
std::type_info::operator==(std::type_info const&) const
std::type_info::~type_info()
std::type_info::~type_info()
std::type_info::~type_info()
typeinfo for std::type_info
typeinfo name for std::type_info
vtable for std::type_info

/gnu/gcc/release/gcc4-4.3.2-2/build/i686-pc-cygwin/libstdc++-v3/libsupc++ $
nm tinfo2.o | grep " [TR] " | cut -d' ' -f3 | c++filt
std::type_info::before(std::type_info const&) const

and there are all these other files with names like
"fundamental_type_info.o" with typeinfo for stuff like int scalars and so on.

  I can't exclude just the first two or the DLL won't link, but the group
of tinfo/tinfo2 and *type_info* seems to form a closed dependency group and
if I exclude them all from export and put them into the import library they
don't get pulled into the DLL's link.  Tests are still running but it solved
regression in 20_util/shared_ptr/thread/default_weaktoshared.cc so far.  I'm
sending a patch separately that adds an ld option to make this kind of
partitioning between DLL and import library easier to perform.

    cheers,
      DaveK