Specify how undefined weak symbol should be resolved in executable

[Carlos O'Donell]

On 02/23/2016 08:56 PM, Alan Modra wrote:
> On Tue, Feb 23, 2016 at 05:18:16PM -0800, H.J. Lu wrote:
>> On Tue, Feb 23, 2016 at 5:04 PM, Alan Modra <amodra@gmail.com> wrote:
>>> On Tue, Feb 23, 2016 at 09:10:51AM -0800, H.J. Lu wrote:
>>>> At run-time, there is no difference between weak defined and non-weak
>>>> defined symbols.
>>>
>>> This is not true, and even if it was..
>>>
>>
>> Please do
>>
>> # git grep dl_dynamic_weak
>>
>> in glibc to see it for yourself.
> 
> That's exactly the code that shows ld.so can treat weak and strong
> symbols differently!  (And yes, I know the default setting of
> dl_dynamic_weak.)
> 
> Besides, the main point of my comment was that it is simply faulty
> reasoning to claim that the linker needs to change because of some
> ld.so behaviour.

Agreed. Anything that brings back weak symbols into the dynamic loader
is going to be highly suspect to me, and require a lot of explaining.

Cheers,
Carlos.