On 6 August 2010 00:38, Brian Gerkey <gerkey@willowgarage.com> wrote:
That is interesting.  I wasn't familiar with that flag.  We clearly
have a lot of overlinking in ROS.  Daniel, have you seen any problems
with using that flag?

I've created a ticket to consider adding it as a default link flag:
https://code.ros.org/trac/ros/ticket/2946 .

         brian.

I had to fix a couple of linkages that went missing in my ros libraries when a dependency didn't get linked in (namely rt and pthreads) but haven't had any other problems. Mind you, haven't been testing this for very long! I'm enabling it as a default in our packages for the moment for testing.

Fedora and now gentoo (which is how I found out about it) are setting this as a default in their builds now (some others as well). Mind you, just because someone else is doing it is no justification, but it does mean its seeing a bit of testing out in the wild and isn't one of those really obscure settings with rather unknown effects.
 
On Thu, Aug 5, 2010 at 12:49 AM, Radu Bogdan Rusu <rusu@willowgarage.com> wrote:
> Interesting. I found some discussions about this at:
> * http://wiki.mandriva.com/en/Overlinking / http://wiki.mandriva.com/en/Underlinking
> * http://www.gentoo.org/proj/en/qa/asneeded.xml
>
> Cheers,
> Radu.
>
> On 08/04/2010 11:02 PM, Daniel Stonier wrote:
>>
>> I didn't know about this linker option until yesterday...turns out to be
>> really useful. Setting -Wl,--as-needed in the ROS_LINK_FLAGS variable
>>   in rosconfig.cmake, we can drop any unused linking dependencies.
>>
>> We've been bashing back and forth here at work on how to build our
>> packages - ideally we want to be able to build a regular algorithm
>> library or device driver with no ros connections so we can use in
>> standalone projects, and also an rosnode lib around that, but
>> unfortunately the manifest drags in all the ros dependencies into the
>> algorithm library/device driver. Up until now, we were splitting into
>> separate packages when we really needed to, but is a bit awkward. There
>> are other use cases too, simple debugging utilities alongside the main
>> library package, or full blown gui tools.
>>
>> This solves all of that. Would there be any reason/disadvantage to
>> having it as a default link flag for gcc in the ros? It's not a big
>> issue as its easy enough to enable globally yourself, but it's something
>> that could just as easily be 'under the hood' so to speak.
>>
>> --
>> Phone : +82-10-5400-3296 (010-5400-3296)
>> Home: http://snorriheim.dnsdojo.com/
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>>
>>
>>
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> --
> | Radu Bogdan Rusu | http://rbrusu.com/
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