Unable to compile v.0.3, v.0.4 and git master on Ubuntu Xenial Xerus (16.04 LTS)

[N0rbert]

I have installed all needed dependencies:

sudo apt-get install qt5-default cmake gcc g++ build-essential git

Cloned your repository and started compilation

git clone https://github.com/pentix/qjournalctl.git
cd qjournalctl
./autogen.sh
make

and got the following error:

xenial@xenial-vb:~/Downloads/qjournalctl$ make
/usr/lib/x86_64-linux-gnu/qt5/bin/uic ui/mainwindow.ui -o ui_mainwindow.h
/usr/lib/x86_64-linux-gnu/qt5/bin/uic ui/aboutdialog.ui -o ui_aboutdialog.h
/usr/lib/x86_64-linux-gnu/qt5/bin/uic ui/showbootlog.ui -o ui_showbootlog.h
g++ -c -pipe -O2 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -isystem /usr/include/x86_64-linux-gnu/qt5 -isystem /usr/include/x86_64-linux-gnu/qt5/QtWidgets -isystem /usr/include/x86_64-linux-gnu/qt5/QtGui -isystem /usr/include/x86_64-linux-gnu/qt5/QtCore -I. -I. -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -o main.o src/main.cpp
g++ -c -pipe -O2 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -isystem /usr/include/x86_64-linux-gnu/qt5 -isystem /usr/include/x86_64-linux-gnu/qt5/QtWidgets -isystem /usr/include/x86_64-linux-gnu/qt5/QtGui -isystem /usr/include/x86_64-linux-gnu/qt5/QtCore -I. -I. -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -o mainwindow.o src/mainwindow.cpp
src/mainwindow.cpp:61:3: warning: identifier ‘nullptr’ is a keyword in C++11 [-Wc++0x-compat]
   message_box.critical(nullptr, "Error", "No boots have been found :\n"+process.readAllStandardError());
   ^
In file included from src/mainwindow.cpp:12:0:
src/showbootlog.h:53:17: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11
  bool sinceFlag=false, untilFlag=false;
                 ^
src/showbootlog.h:53:34: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11
  bool sinceFlag=false, untilFlag=false;
                                  ^
src/showbootlog.h:54:23: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11
  bool completeJournal=false;
                       ^
src/showbootlog.h:55:16: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11
  bool realtime=false;
                ^
src/showbootlog.h:56:15: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11
  bool reverse=false;
               ^
src/showbootlog.h:57:18: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11
  int maxPriority=3;
                  ^
src/showbootlog.h:58:24: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11
  int numberOfBytesRead=0;
                        ^
src/showbootlog.h:59:26: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11
  QString identifierFlags="";
                          ^
src/mainwindow.cpp: In member function ‘void MainWindow::on_listBootsButton_clicked()’:
src/mainwindow.cpp:61:24: error: ‘nullptr’ was not declared in this scope
   message_box.critical(nullptr, "Error", "No boots have been found :\n"+process.readAllStandardError());
                        ^
src/mainwindow.cpp: At global scope:
src/mainwindow.cpp:141:64: warning: unused parameter ‘index’ [-Wunused-parameter]
 void MainWindow::on_tableView_doubleClicked(const QModelIndex &index)
                                                                ^
src/mainwindow.cpp:172:58: warning: unused parameter ‘index’ [-Wunused-parameter]
 void MainWindow::on_tableView_clicked(const QModelIndex &index)
                                                          ^
Makefile:371: recipe for target 'mainwindow.o' failed
make: *** [mainwindow.o] Error 1

So your great program does not compile on LTS Ubuntu version. Only previous v.0.21 version compiles normally on Ubuntu. IMHO creating software only for bleeding-edge Arch is not good idea.

Note: first seen on AskUbuntu.

[pentix]

Hi, thank you very much for pinging me on this issue! Also thanks for helping out the other user in the AskUbuntu forum!

At the first sight it seems as if g++ does not automatically compile for C++11 (that's why it suggests to use the -std=c++11. Also the variable nullptr is defined when using the C++11 standard.

As a first workaround, you could execute ./autogen.sh and then edit the Makefile. On approximately line 17 you should see something like

CXXFLAGS      = -pipe -O2 -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -Wall -W -D_REENTRANT -fPIC $(DEFINES)

Add the flag there

CXXFLAGS      = -std=c++11 -pipe -O2 -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -Wall -W -D_REENTRANT -fPIC $(DEFINES)

Then try again, running

make clean
make

I totally agree that it should not only run on bleeding-edge systems but Ubuntu just sometimes really takes years to update the software in their repositories, because compiling for C++11 should (in my opinion) not require any flag anymore (at least now, that C++14 and C++17 are already more or less published and used...) and gcc also already changed this some years ago.

BTW: I also found this (https://stackoverflow.com/a/44735016/2628569) code snippet to show you the default C++ version your compiler compiles.

I see that this is an issue and as soon as I find time I will add this as a default option so you won't have to edit the Makefile manually anymore. ☺️

Please tell me if the given workaround works for you! Thanks again!

[dopsi]

Hi @pentix,

What about adding the CONFIG += c++11 [1] to the qjournalctl.pro file ?

[pentix]

@dopsi Thanks for this, I didn't quite have the time to look it up but this seems like the most reasonable to do. In my environment this adds -std=gnu++11 to the Makefile.

@N0rbert Could you try to do

git pull make clean ./autogen.sh make

I hope by adding what @dopsi mentioned, it should compile now! 😄

Edit: I already plan some more stuff to be implemented soon (1 week, post-examination phase 😅), and I'm a bit short of time, that's why I did not increase and publish a new version for now. But compiling the master branch should work now :)

[N0rbert]

Thank you for fast response and fix! I cloned master again, it compiles and runs on Ubuntu 14.04 LTS, 16.04 LTS and 18.04 LTS without any user intervention.