Re: RFC: .gnu.linkonce.* and shared libraries

[Jason Merrill <jason_merrill at redhat dot com>]

>>>>> "Jakub" == Jakub Jelinek <jakub@redhat.com> writes:

> On Wed, Jul 11, 2001 at 02:11:06PM -0700, Ian Lance Taylor wrote:
>> Jakub Jelinek <jakub@redhat.com> writes:
>> 
>> > I perhaps have not written it clearly.
>> > All of 1)-4) would be done in the static linker, not dynamic linker.
>> 
>> Sorry, I misunderstood.
>> 
>> The only relevant issue then is that your scheme is robust in the face
>> of running against a dynamic library which is not the specific one
>> which was linked against.

> That's why the compiler/programmer has to ask for it explicitely.
> As far as I understand C++, having e.g. different vtables in a program would
> make it non-conforming.

Considering the entire program, perhaps.  The problem comes when the stuff
in .gnu.linkonce.foo is not part of the intended API of the library, but a
side effect of the implementation.  If the implementation changes (say, to
use list<T> instead of vector<T>), the instantiations present in the
library change, so if the linker had decided the executable could just use
the vector<int> code in the library things break.

Jason