Challenge for real experts: why does cmake on CI not use automoc for a certain file?

[Alex Merry]

On Friday 05 June 2015 00:58:30 Friedrich W. H. Kossebau wrote:
> you are a cmake and KDE buildsystem expert?
> Prove that yourself and improve the world for others ;)

Or, indeed, work towards becoming such an expert...

> 
> Here is the challenge:
> 
> https://build.kde.org/job/calligra%20frameworks%20kf5-qt5/PLATFORM=Linux,Var
> iation=All,compiler=gcc/28/consoleText
> 
> CMakeFiles/KisAsyncMergerTest.dir/kis_async_merger_test.cpp.o: In function
> `KisAsyncMergerTest::KisAsyncMergerTest()':
> /home/jenkins/builds/calligra/kf5-
> qt5/krita/image/tests/kis_async_merger_test.h:24: undefined reference to
> `vtable for KisAsyncMergerTest'
> CMakeFiles/KisAsyncMergerTest.dir/kis_async_merger_test.cpp.o: In function
> `KisAsyncMergerTest::~KisAsyncMergerTest()':
> /home/jenkins/builds/calligra/kf5-
> qt5/krita/image/tests/kis_async_merger_test.h:24: undefined reference to
> `vtable for KisAsyncMergerTest'
> collect2: error: ld returned 1 exit status
> krita/image/tests/CMakeFiles/KisAsyncMergerTest.dir/build.make:89: recipe
> for target 'krita/image/tests/KisAsyncMergerTest' failed
> 
> Right, you say, smells like automoc not run. And indeed it is not run. So
> far you are an expert.
> 
> But why?
> Why does cmake on CI not want to run automoc on
> kis_async_merger_test.{h,cpp}?
> 
> Locally it works fine for anyone (cmake 3.0.1/3.0.2), noone yet was able to
> reproduce the problem, instead everyone sees:

So my first question is: what version of cmake is being run on the build 
servers? If it's not 3.0.1 or 3.0.2, then that could explain why you can't 
reproduce it locally.

Alex