title: gtkmm fails on linking on Fedora 30
body: <p>I would appreciate help to get "gtkmm-3.0" (the C++ interface for the Gtk+ 3 library) running on Fedora 30. I had no problems with it in Fedora 29.</p>
  
  <p>I installed gtkmm using:</p>
  
  <pre><code>dnf install gtk3 gtk3-devel gtkmm30 gtkmm30-devel
  </code></pre>
  
  <p>To test it I used the simple .cpp file commonly available on the Net, e.g. 
  <a href="https://gtkmm-tutorial.blogspot.com/2016/05/how-to-install-gtkmm-on-CENTOS-7-RedHat-Fedora-in-3-steps.html" rel="nofollow noreferrer">https://gtkmm-tutorial.blogspot.com/2016/05/how-to-install-gtkmm-on-CENTOS-7-RedHat-Fedora-in-3-steps.html</a></p>
  
  <pre><code>#include &lt;gtkmm.h&gt;
  int main(int argc, char *argv[])
  {
    Gtk::Main kit(argc, argv);
    Gtk::Window GtkmmTutorial;
    GtkmmTutorial.set_default_size(400, 400);
    Gtk::Main::run(GtkmmTutorial);
    return 0;
  }
  </code></pre>
  
  <p>Given the file name "GtkmmTutorial.cpp", I compiled it from the same directory using:</p>
  
  <pre><code>g++ GtkmmTutorial.cpp -o GtkmmTutorial `pkg-config gtkmm-3.0 --cflags --libs`
  </code></pre>
  
  <p>Compilation failed with the error message:</p>
  
  <pre><code>Package gtkmm-3.0 was not found in the pkg-config search path.
  Perhaps you should add the directory containing `gtkmm-3.0.pc'
  to the PKG_CONFIG_PATH environment variable
  Package 'gtkmm-3.0', required by 'virtual:world', not found
  GtkmmTutorial.cpp:1:10: fatal error: gtkmm.h: No such file or directory
      1 | #include &lt;gtkmm.h&gt;
        |          ^~~~~~~~~
  compilation terminated.
  </code></pre>
  
  <p>I found gtkmm-3.0.pc and gdkmm-3.0.pc in "/usr/lib/pkgconfig/", so as instructed did:</p>
  
  <pre><code>export PKG_CONFIG_PATH="/usr/share/pkgconfig"
  </code></pre>
  
  <p>At the next attempt to compile I got this error message:</p>
  
  <pre><code>/usr/bin/ld: skipping incompatible /usr/lib/libgtkmm-3.0.so when searching for -lgtkmm-3.0
  /usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-redhat-linux/9/../../../libgtkmm-3.0.so when searching for -lgtkmm-3.0
  /usr/bin/ld: skipping incompatible //lib/libgtkmm-3.0.so when searching for -lgtkmm-3.0
  /usr/bin/ld: skipping incompatible //usr/lib/libgtkmm-3.0.so when searching for -lgtkmm-3.0
  /usr/bin/ld: cannot find -lgtkmm-3.0
  /usr/bin/ld: skipping incompatible /usr/lib/libgdkmm-3.0.so when searching for -lgdkmm-3.0
  /usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-redhat-linux/9/../../../libgdkmm-3.0.so when searching for -lgdkmm-3.0
  /usr/bin/ld: skipping incompatible //lib/libgdkmm-3.0.so when searching for -lgdkmm-3.0
  /usr/bin/ld: skipping incompatible //usr/lib/libgdkmm-3.0.so when searching for -lgdkmm-3.0
  /usr/bin/ld: cannot find -lgdkmm-3.0
  collect2: error: ld returned 1 exit status
  </code></pre>
  
  <p>There are no files "lgtkmm-3.0" or "lgdkmm-3.0" on either my F30 or my F29 system (which has almost identical .pc files, just minor variations in version numbers). Nor can I locate such files on the Net.</p>
  
  <p>Not sure where to head next... Thanks for any input.</p>