Re: Minimal GCC/Linux shared lib + EH bug example

[martin at v dot loewis dot de (Martin v. Loewis)]

"David Abrahams" <david.abrahams@rcn.com> writes:

> If I understand correctly, weak symbols were introduced to allow things
> like users replacing malloc, free, operator new, etc. 

That's why they were introduced, yes. It turns out that they are
useful for a number of other things: you can emit duplicate
definitions of the same symbol, and it won't be a linker error. This
usage is particularly important for C++, to support virtual tables,
typeinfo objects, template instantiations, etc.

> I think the same case could be made by putting malloc/free replacements in
> each of two extension modules which are linked to a common shared lib,
> right? 

Not sure what "the same case" is, here.

> Then memory allocated by ext2 couldn't be freed by the common lib,
> and vice-versa.

If both ext1 and ext2 override the allocator in libcore, then all
calls in libcore would use the definition in ext1, but calls in ext2
would use their own definition, yes.

> Can you think of a more-minimal or more-compelling test case?

Think of: yes, I would just make three functions, each printing a
different message. It's not a compelling test case, but it
demonstrates the difference to Solaris, and it demonstrates that the
libcore and ext2 use different definitions, even though they are
linked together.

Regards,
Martin