[cmake-developers] Apple tests for target_link_libraries failing

[Rolf Eike Beer]

> Rolf Eike Beer wrote:
>
>>>> Stephen Kelly wrote:
>>>>
>>>>> The tests can be enabled on APPLE again later, I've flipped the if
>>>>> condition so we can see why it fails on some non-APPLE platforms too.
>>>>>
>>>>
>>>> This is even more interesting now.
>>>>
>>>> http://www.cdash.org/CDash/testDetails.php?test=118872016&build=1620094
>>>>
>>>> On gentoo, the build of the exec executable succeeds, even though it
>>>> only
>>>> links to libC, and that only links to libA, even though it uses classB
>>>> from
>>>> libB (which is not linked to).
>>>
>>> libB is in the needed section (see below). The only special thing that
>>> I
>>> can think of is the -Wl,--unique=.text.* flag I put into C_FLAGS, as
>>> CMake itself would otherwise not link because of a binutils breakage.
>>> No
>>> idea if that is related.
>>
>> Ok, it is not related. I rebuild only that testcase without that flag
>> and
>> it did not change anything.
>>
>> But I noticed another thing. In the dashboard above 2 tests are failing:
>> 19 and 20. I think the test #20 is actually wrong, as it seems to depend
>> on linker flags that may just be activated by default on the machines
>> you use. If I manually specify
>> LDFLAGS=-Wl,--no-copy-dt-needed-entries,--as-needed when I call CMake
>> for the first time #20 succeeds for me. So it looks like this is just
>> "accidentially" working, but in fact you may need to pass these flags
>> yourself to make sure they are always there.
>
> You mean everyone needs to specify them if they use
>
> LINK_INTERFACE_LIBRARIES ""
>
> anywhere, right?

I don't meant that. What does not mean that this may not be true. I just
have no idea ;)

It may even mean that you have to test if that works at all, older
binutils may not have this. I don't know.

> If that's true then setting that variable to empty should maybe add those
> flags automatically.
>
> I'm not certain that's correct though. Those flags don't seem to be used
> when I build. I also don't know what those flags do.
>
> Linking CXX executable exec
> /home/stephen/dev/qt48/kde/bin/cmake -E cmake_link_script
> CMakeFiles/exec.dir/link.txt --verbose=1
> /usr/lib/icecc/bin/c++       CMakeFiles/exec.dir/main.cpp.o  -o exec -
> rdynamic lib/liblibC.so
> -Wl,-rpath,/home/stephen/cmaketest/test19/build/lib
> -Wl,-rpath-link,/home/stephen/cmaketest/test19/build/lib
> CMakeFiles/exec.dir/main.cpp.o:main.cpp:function main: error: undefined
> reference to 'classB::classB()'
> collect2: ld returned 1 exit status
> make[2]: *** [exec] Error 1
> make[2]: Leaving directory `/home/stephen/cmaketest/test19/build'

Maybe this is just the default setting for your binutils. Try
LDFLAGS=-Wl,--copy-dt-needed-entries,-no-as-needed and see what happens. I
bet this will change the behavior on your system.

Eike