without success, I need help of experienced.

I need .zip support in my app. In Qt4, it was simple: install kdelibs5-dev and link with libkdecore.so . Doing the same in Qt5 results in an immediate crash.

There is KArchive on inqlude. I downloaded it and tried to build it using included instructions. The build failed because I didn't have ECMConfig.cmake. Searching what it is all about, I have found I need extra-cmake-modules package, which isn't in the repository but which is on inqlude (in sources) - now without any instructions what to do with it. I tried to create a buid directory and commanded cmake .. from it. It failed, too, because I haven't something else. Oh well, install qttools5-dev and qttools5-dev-tools and cmake .. will pass. Now I seem to have ECMConfig.cmake but on a wrong place.

Q: Supposing cmake .. was a correct idea, where to copy the contents of the build directory of extra-cmake-modules?
Q: Will KArchive buid now? Or I need to install something before building?

In the meantime, I tried to make a Qt5 project from the KArchive sources and create a static library. With some problems, I was seemingly successful in the end. Linking the library with my app failed with unresolved external (init2) in a private header (kgzipfilter.h). So it isn't so simple. I also tried kdelibs5-dev again (in installs lots of Qt4, that's why I tried to avoid kdelibs5-dev) but with the known result (immediate crash).