[zeromq-dev] Example for building against ZMQ with CMake + UDP Multicast Support

[Luca Boccassi]

On 10 January 2017 at 21:33, Stephan Opfer <opfer at vs.uni-kassel.de> wrote:
> On 10.01.2017 22:20, Luca Boccassi wrote:
>>
>> luca at luca-desktop:/tmp$ apt-cache policy libzmq3-dev
>> libzmq3-dev:
>>    Installed: 1483950852.598befc
>>    Candidate: 1483950852.598befc
>>    Version table:
>>   *** 1483950852.598befc 0
>>
>> 500http://download.opensuse.org/repositories/home:/zeromq:/git-draft/Debian_8.0/
>> ./ Packages
>>          100 /var/lib/dpkg/status
>>       4.2.1-2 0
>>          103http://httpredir.debian.org/debian/  sid/main amd64 Packages
>>       4.2.0-2 0
>>          104http://httpredir.debian.org/debian/  stretch/main amd64
>> Packages
>>       4.0.5+dfsg-2+deb8u1 0
>>          500http://httpredir.debian.org/debian/  jessie/main amd64
>> Packages
>>          500http://security.debian.org/  jessie/updates/main amd64
>> Packages
>> luca at luca-desktop:/tmp$ g++ `pkg-config --libs --cflags libzmq`
>> Discovery.cpp -o test
>> luca at luca-desktop:/tmp$ ./test
>>
>>
>> Builds just fine (binary runs and never exits not sure if that's
>> intended). I am honestly not sure why your linker is being picky. This
>> is on Debian 8 with gcc 4.9.2
>
> $ apt-cache policy libzmq3-dev
> libzmq3-dev:
>   Installed: 1483950852.598befc
>   Candidate: 1483950852.598befc
>   Version table:
>  *** 1483950852.598befc 500
>         500
> http://download.opensuse.org/repositories/home:/zeromq:/git-draft/xUbuntu_16.04
> ./ Packages
>         100 /var/lib/dpkg/status
>      4.1.4-7 500
>         500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
>
> A little bit strang, that I don't see a Version named 4.2.x like you have.
> Nevertheless, this would only create a lack of the new UDP Multicast
> feature, but my linker complains about standard functions like
> zmq_ctx_new...
>
> I am using g++ version 5.4.0 on Ubuntu 16.04 LTS. I further guaranteed that
> there is only one libzmq.
> Its location is: /usr/lib/x86_64-linux-gnu/libzmq.so.5.1.2
> And I checked that the wanted symbol is in there with: readelf -Ws
> /usr/lib/x86_64-linux-gnu/libzmq.so.5.1.2
>
> Normally under this circumstances problems like mismatching architecture of
> the .so is the case, but I can't see any hints for that.

Uh, I have an Ubuntu 16.04 machine around and I can indeed reproduce
the same problem. This is weird. Investigating...