On 5 March 2013 12:27, Jonathan Wakely <jwakely.gcc@xxxxxxxxx> wrote: > On 5 March 2013 10:39, <Heiko.Papenfuss@xxxxxxxxxxx> wrote: > > Does this mean that it would be possible to link with any GCC that > > supports -fabi-version=2 against any libstdc++.so.6.x.y? > > I'm not sure I understand what you're asking. > > GCC doesn't do linking, it just forwards arguments to the linker. The > -fabi-version option is not used at link-time, that only affects > code-generation at compile-time. So in theory you can use *any* gcc > driver to link compatible objects together if you explicitly say which > libstdc++.so to use, because the list of objects and libraries will be > forwarded to the linker, but just using the g++ driver that matches > that libstdc++.so is by far the simplest approach. > > Also, you can't link against *any* libstdc++.so.6.x.y, you must link > against a version that is no older than required by any of your > objects. If your program consists of three objects and you compile > foo.o and bar.o with GCC 4.1.2 and baz.o with GCC 4.6.3 then you must > link your program to libstdc++.6.0.16 or later, because baz.o will > depend on the GLIBCXX_3.4.16 version that is only found in > libstdc++.so.6.0.16 and later. > > If that doesn't answer your question please be more specific, > providing a concrete example with commands showing what you're asking > about. Despite my unclear wording that is what I wanted to know. > > Another question comes to my mind here: Let's assume I have two object files > > or libraries that have been compiled separately and were compiled with > > different versions of GCC thus needing different versions of libstdc++.so > > at run-time. Do I read [2], "Multiple ABI Testing", correctly that I should > > be able to compile and run a program which uses both libraries provided that > > the most current libstdc++.so that any library depends on is present at > > run-time? > > The "Multiple ABI Testing" docs refer to using incompatible libraries, > e.g. libstdc++.so.5 and libstdc++.so.6, in the same process. It's hard > to get right, can only be done if no library types (or type_info or > exceptions or polymorphic types) cross library boundaries, and I'm not > sure those docs are 100% accurate. If you just want to link objects > compiled with GCC 4.X with objects compiled with GCC 4.Y then that > section of the docs is not relevant. > Thanks for clarifying that for me! Heiko
