Re: Proposed change: weak symbol support for Darwin

[Joe Buck <jbuck at synopsys dot com>]

On Mon, Oct 13, 2003 at 06:28:21PM -0700, Matt Austern wrote:
> It's not that hard.  Currently we've got four cases for polymorphic 
> classes:

Which really reduce to two: your case 1 where we use the cfront trick,
and everything else where we can't.

> I'm describing what the compiler currently does, by the way, not my 
> proposal.
> And currently we make the vtable weak for all four cases.
> 
> My proposal is to change the compiler, for Darwin only, so that it only
> makes the vtables weak for cases 2-4.  I don't see any good reason to 
> make
> that change on any other platforms, but I'd be happy to do it if anyone 
> can
> think of a reason why it would be an improvement.

There's the maintainance issue: maintainers forever more will have to
ask themselves why Darwin is different, even though some other OSes
have similar issues with weak symbols.

I think that just making the change everywhere would be better.
For one thing, x86/ELF using developers will notice that they have
broken Darwin a bit earlier. :-)

In fact, anything that can be done to easily reduce the number of
special cases, multiple ways of doing things, and OS-specific tweaks
in gcc that aren't really needed will pay off in the long run.