This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Question on DSO and visibility


I wonder if someone can comment on this situation: I'll do some testing
but I likely can't test everything.

I'm creating DSO's for GNU/Linux with GCC 4.9.2 right now.  I want to
upgrade to GCC 6.2.0.  My code is written in C++.  I'm aware of the C++
STL ABI break in GCC 5.x.

I have users who will be using my library who are also writing C++ code
and they will be using older versions of GCC (I build my own GCC and I
use a specific sysroot for an older version of libc etc. so I know my
code will run properly on their system: they'll use their distribution's
version of GCC).

What I was thinking of doing was this:
   1. Link my DSO with -static-libstdc++ and -static-libgcc
   2. Ensure that no STL typed objects are passed across the ABI between my
      library and its callers; also that no memory I allocate is freed by
      the user and no memory the user allocates is freed by me (my library
      also runs on Windows as a DLL so I already have this restriction).
   3. Use a linker map to make all symbols in my DSO hidden except the
      specific ones I want to be public.  I use a linker map and not just
      -fvisibility=hidden, so that all the symbols I've statically linked
      from libstdc++.a will also be marked hidden (since libstdc++.a was
      not compiled with -fvisibility=hidden).

Is this plan sufficient to allow people to link with my library and not
have their version of GCC's libstdc++.so interfere with my library's
version, so the different ABI's can coexist in the same program without
interfering with each other?

In other words, I can use std::basic_string and std::list in my library
and get the C++11 ABI from GCC 6.2 that I've statically linked, and
users can use std::basic_string and std::list in their code and get
their version of the libstdc++.so (presumably that is provided by their
GNU/Linux distribution) and all will work properly.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]