Is there a way to set the elf NEEDED field at link time?

Question

Given a executable such that:

>objdump -x someprog | grep c++
NEEDED               libstdc++.so.6

I want to change the requirement to the fu

Answer 1

This will not work because libstdc++.so.6.0.22 will export the same symbols as the system libstdc++, and you will end up with a wild mix between the two libraries (assuming you indeed change the soname of the newer libstdc++ version).

You should either link the whole of libstdc++ statically (this may require a static PIC variant of the library) and not export any symbols (probably with a linker version script), or link only the new symbols statically.

The second approach seems to be the best option at present: It allows you to use most new language features, but you have still a large degree of interoperability with the rest of the system (especially if you configure GCC with --with-default-libstdcxx-abi=gcc4-compatible), and you don't have to install any additional shared objects for deployment. This is how the Developer Toolset software collection provides newer versions of GCC (and I believe the SUSE Linux Toolchain Module, too). Full static linking causes problems if C++ objects are passed across shared object boundaries (which includes exception handling), and this kind of selective static linking avoids many of these these problems.