Compiling SEMPR with Qt5

The only part restricting the version of qt (and which originally introduced qt to sempr) is the RDF stuff, namely soprano. Soprano 2.9.4 (latest release, quite a few years old) relies on qt4, but on the kde-repo a commit exists that should enable compilation with qt5.

First, make sure that you remove all occurrences of soprano from your system.

sudo apt-get remove soprano-daemon libsoprano4

Check that you have installed qt5:

pkg-config --libs Qt5Core

If not, install qt5.

redland backend

To also compile the redland-backend with qt5, you need the librdf0-dev package. This provides the necessary development files. One problem with installing this through apt-get, though, is that libraptor2-dev depends on libcurl4-gnutls-dev, which conflicts with libcurl4-openssl-dev and thus will uninstall e.g. ROS....

There are 2 possibilities:

1. You don't need ROS / don't need libcurl4-openssl-dev. In that case, just do sudo apt-get install librdf0-dev and let it handle all the dependencies, which will include libcurl4-gnutls-dev.

2. You need ROS / or at least libcurl4-openssl-dev . In that case, do the following:

   1. Download libraptor2-dev:

      apt-get download libraptor2-dev
      

   2. Install it through dpkg, ignoring the libcurl4-gnutls-dev-dependency:

      sudo dpkg --ignore-depends=libcurl4-gnutls-dev -i libraptor2-dev_2.0.14-1_amd64.deb 
      

   3. This might tell you that other dependencies are not fulfilled. In my case, this was:

      dpkg: dependency problems prevent configuration of libraptor2-dev:
       libraptor2-dev depends on libxslt1-dev (>= 1.0.18); however:
        Package libxslt1-dev is not installed.
       libraptor2-dev depends on libyajl-dev; however:
        Package libyajl-dev is not installed.
      

      So, go ahead and install them. But sudo apt-get install ... will complain about libraptor2-dev, so you will want to remove it again, e.g. using sudo apt-get install -f.

      # install missing deps -- see output of dpkg
      sudo apt-get install libxslt1-dev libyajl-dev # will fail due to "broken" packages
      sudo apt-get install -f # removes libraptor2-dev
      sudo apt-get install libxslt1-dev libyajl-dev # will now work
      

      And again, install libraptor2-dev:

      sudo dpkg --ignore-depends=libcurl4-gnutls-dev -i libraptor2-dev_2.0.14-1_amd64.deb 
      

      This should now succeed. However, since the dependency was just ignored, apt-get will now complain about this broken package and refuse to install anything else before fixing this. Sadly, there is not --shut-up-and-install-option in apt-get. So we need to trick it into thinking that it was installed correctly and everything is fine, in the next step.

   4. How to trick apt-get? We are going to change the dependencies of the installed libraptor2-dev package from ...-gnutls-dev to ...-openssl-dev, since that is what ROS uses and conflicts here. Is this "ok"? Certainly not. It's hacky. It's bad. Let's proceed anyway, because: We only do this to compile soprano once. Feel free to revert everything after we are done. sudo apt-get remove libraptor2-dev will remove all this hacky stuff, and it's okay, since we only need it to compile soprano. At runtime we will only need libraptor2-0, which is no problem at all.

      So, to trick apt-get into thinking everything's okay:

      sudo vim /var/lib/dpkg/status
      
      # find this entry:
      [...]
      Package: libraptor2-dev
      Status: install ok installed
      Priority: optional
      Section: libdevel
      Installed-Size: 898
      Maintainer: Ubuntu Developers <[email protected]>
      Architecture: amd64
      Source: raptor2
      Version: 2.0.14-1
      Depends: libraptor2-0 (= 2.0.14-1), libxml2-dev (>= 2.5.10), libcurl4-gnutls-dev, libxslt1-dev (>= 1.0.18), pkg-config, libyajl-dev
      [...]
      # and modify the "Depends:" part:
      # from "libcurl4-gnutls-dev" to "libcurl4-openssl-dev". or delete it altogether, whatever.
      

   5. No you can install all the redland-dev-stuff:

      sudo apt-get install librdf0-dev
      

   6. Remember that you may want to clean this mess up (remove libraptor2-dev) after you finished installing soprano.

compile soprano with qt5

Afterwards, clone the soprano repository which is patched for qt5-support, build and install it.

(Patched with qt5-plugin export makros and pkgconfig file. FYI: The export patch is written by Denis Kuplyakov and originally posted on the soprano mailing list.)

mkdir soprano_qt5 && cd soprano_qt5
mkdir install

git clone https://github.com/sempr-tk/soprano_qt5.git
cd soprano_qt5

# compile with qt5
mkdir build && cd build
cmake .. -DQT5_BUILD=true -DCMAKE_INSTALL_PREFIX=~/soprano_qt5/install
make -j8 install

# add install dir to pkg-config path
# (e.g. in .bashrc)
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:~/soprano_qt5/install/lib/pkgconfig

# make sure the correct version of soprano is found
pkg-config --libs soprano # search for -lQt5Core

Now, if you hacked your way around the libcurl4-[gnutls|openssl]-dev problem you might want to do sudo apt-get remove libraptor2-dev since we don't need the hacked-in packed anymore.

Congratulations, you now have soprano with qt5-support. If you now do a fresh build of sempr it will use qt5, too.