[PATCH][darwin] revert to .weak_definition on darwin<10

[Iain Sandoe]

Hi Jim,

On 10 Dec 2013, at 00:02, Jim Grosbach wrote:
> 
> On Dec 9, 2013, at 2:41 PM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
> 
>> On 6 December 2013 14:22, David Fang <fang at csl.cornell.edu> wrote:
>>> It seems I am not very good at attaching patches.
>>> How does this look?
>> 
>> MCAsmInfo has a hasWeakDefDirective. I would suggest adding a
>> hasWeakDefCanBeHiddenDirective instead of inlining the check on the
>> AsmPrinter.
>> 
>> I will let Grosbach comment on which targets/versions we should do this for.
> 
> <10 seems reasonable to me.
> 
> I don’t like using the target version for this, but as the FIXME indicates, there’s not a better answer available right now, so pragmatically this will get things working. It’s also simple enough that when/if we do get a better answer, this doesn’t make it harder to do so.

Would a patch to pass target-linker-version into the target instantiation be acceptable?
(this is/was my plan when I next have a few mins).

We can then key codegen on the correct thing.

ISTM that when a compiler is "inherently a cross compiler" *and* is under development *and* might be used with a bunch of different exterior tools, that passing the linker and assembler version to the codegen is a sensible step (at least during the development phase).

However, as commented before, this param seems to reach compiler invocation and then get dropped on the floor.
Iain