[CMake] Undefined reference

[Michael Hertling]

On 11/03/2011 03:51 PM, Mauricio Klein wrote:
> Thank you Raphael, it worked!
> 
> One last question: i've tried to compile my code using static linkage, once
> i need my daemon runs in many Linux releases. But, even static, in many
> systems my code crashes because the GLIBC version.

How do these crashes manifest themselves, e.g. shell/syslog messages,
return values, core dumps etc.? Are you sure they are related to the
GLIBC version? Does the executable actually have no single dependency
on any shared library, i.e. is it linked statically in its entirety?
What does ldd or readelf report?

> My question is: asking for static linkage in CMake can solve this problem?

If even a statically linked executable crashes on the target system,
telling CMake to link statically will hardly solve this problem. ;)

> Or maybe another approach in CMake, where i embed all the needed
> libraries...

You might take a look the the BundleUtilities Module, but at first,
I'd recommend to investigate what exactly causes the crashes. Your
best bet is probably to provide a tiny but self-contained example
that works on your development platform and crashes on a target
system, along with some information about the latter's setup.

Regards,

Michael

> On Thu, Nov 3, 2011 at 12:19 PM, Raphael Kubo da Costa
> <rakuco at freebsd.org>wrote:
> 
>> Mauricio Klein
>> <mauricio.klein.msk at gmail.com> writes:
>>
>>> I can compile all my codes without problems, but in the linkage step, i
>>> receive a lot of errors about undefined reference to OpenSSL functions
>>> (yes, my code uses OpenSSL).
>>>
>>> In my own (and ugly :P) Makefile, i use "-lssl" flag in g++ compile line.
>>>
>>> My question is: how can i pass this flag in CMake.
>>> Also, i'm not sure if i'm using CMake correctly. Is correctly use "-lssl"
>>> flag in CMake or i need to copy the library to a folder inside my project
>>> and link to this copy?
>>
>> You need to find OpenSSL with `find_package(OpenSSL)' and then, assuming
>> it is found (ie. OPENSSL_FOUND is true), link to its libraries with
>> `target_link_libraries(YOUR_APP ${OPENSSL_LIBRARIES})'.