How to compile QCustomPlot for OSX?

Question

I am usually working on Ubuntu, using CMake and native environment. My project compiles and runs fine. Now I changed to OSX and first of all I receive some warnings when compiling QCustomPlot:

QCustomPlot/include/qcustomplot.h:6007:15: warning: 
      'findEnd' overrides a member function but is not marked 'override'
      [-Winconsistent-missing-override]
  virtual int findEnd(double sortKey, bool expandedRange=true) const;
              ^
../QCustomPlot/include/qcustomplot.h:3830:15: note: 
      overridden virtual function is here
  virtual int findEnd(double sortKey, bool expandedRange=true) const = 0;

I suppose I can suppress this warning. I do not like, however, to suppress warnings, if they can mean a real danger. (under Ubuntu, there is no warning). Why is it a warning? I think to override a virtual function is not really unusual or dangerous.

Anyhow, with warnings, but dompiles. The real problem appears with linking

[  4%] Building CXX object QCustomPlot/CMakeFiles/libQCustomPlot.dir/libQCustomPlot_automoc.cpp.o
[  5%] Linking CXX shared library libQCustomPlot.dylib
Undefined symbols for architecture x86_64:
  "qt_assert_x(char const*, char const*, char const*, int)", referenced from:
      QList<QCPDataRange>::at(int) const in qcustomplot.cpp.o
      QList<QCPDataRange>::operator[](int) in qcustomplot.cpp.o

What is the problem here? (as using a multiplatform development environment, I did not expect any missing file, component, or similar problem.)

Edit: here goes the CMake file that produced it

set(CMAKE_AUTOMOC ON)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
find_package(Qt5 COMPONENTS Core Widgets PrintSupport REQUIRED)

include_directories(
      ${Qt5Widgets_INCLUDE_DIRS}
      ${Qt5Printer_INCLUDE_DIRS}
      include
      )

add_definitions(${Qt5Widgets_DEFINITIONS} ${Qt5Printer_DEFINITIONS})

QT5_WRAP_CPP(qcustomplot_moc include/qcustomplot.h)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${Qt5Widgets_EXECUTABLE_COMPILE_FLAGS}  -std=c++11 -Wall")

ADD_LIBRARY(libQCustomPlot
    qcustomplot.cpp
    ${qcustomplot_moc} # The MOC headers, generated
)

set_target_properties(libQCustomPlot
                      PROPERTIES OUTPUT_NAME QCustomPlot
                      )
target_include_directories(libQCustomPlot PUBLIC
  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
)

I would really be glad, if before/after/instead/in_addition_to downvoting, you would leave a comment, why. — katang
– katang, Commented Jan 2, 2017 at 10:03
I did not downvote, but I think you should provide more details about the error: Run "make VERBOSE=1" instead of "make" to see what libraries are being linked to. In particular look for Qt5Core, which should be the one containing qt_assert_x. Can you successfully build something with qmake? For example, the QCustomPlot examples? The warning is nothing to worry about; it is suggesting to use the override specifier, which was introduced in C++11. But I guess QCustomPlot keeps compatibility with older C++. If you don't need C++11, then set (CMAKE_CXX_STANDARD 98) should remove the warning. — pepan
– pepan, Commented Jan 4, 2017 at 16:39

Sebastian Brosch · Accepted Answer · 2017-09-29 18:17:56Z

0

The CMakeLists.txt is missing the line

target_link_libraries(libQCustomPlot Qt5::Widgets)

See the Qt documentation on compiling with CMake. In addition, unless the CMakeLists.txt needs to support CMake versions older than 3.0, a lot of its current contents can be removed. It can be reduced to something like this:

set(CMAKE_AUTOMOC ON)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
find_package(Qt5 COMPONENTS Core Widgets PrintSupport REQUIRED)

include_directories(include)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -W -Wall")

ADD_LIBRARY(libQCustomPlot
    qcustomplot.cpp
)

set_target_properties(libQCustomPlot
                      PROPERTIES OUTPUT_NAME QCustomPlot
                      )

target_link_libraries(libQCustomPlot Qt5::Widgets)

target_include_directories(libQCustomPlot PUBLIC
  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
)

More details about GCC not failing on undefined references can be found in this question.

The warning is about a missing override specifier in a function that overrides another function. The following will avoid the warning:

virtual int findEnd(double sortKey, bool expandedRange=true) const override;

edited Sep 29, 2017 at 18:17

Sebastian Brosch

43.8k15 gold badges78 silver badges89 bronze badges

answered Jan 5, 2017 at 9:06

pepan

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5 Comments

katang Over a year ago

Thanks for the detailed explanation. I did not search in this direction, because the same CMake file compiles, links and runs under Ubuntu.

katang Over a year ago

If I omit ${Qt5Widgets_INCLUDE_DIRS} from include_directories(), I receive error message QtCore/qglobal.h not found. If I remove QT5_WRAP_CPP(qcustomplot_moc include/qcustomplot.h), I receive error messages of type undefined reference to vtable for QCPCurve'.

pepan Over a year ago

What is your CMake version? If you do not remove anything, but just add the target_link_libraries line, does everything compile?

katang Over a year ago

cmake version 3.5.1

pepan Over a year ago

If this missing include file happens even when you have the target_link_libraries line, then this is strange. You may try if it is possible to compile some simple Qt example using the CMakeLists.txt file from the Qt documentation link that I provided in the answer.

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