[QGIS-Developer] Building QGIS using Qt 5.14.2

[Ismail Sunni]

Dear QGIS developers,

I am trying to build QGIS using Qt 5.14.2. I have installed the Qt 5.14.2.
I have also set the CMake configuration (all Qt5*_Dir parameter) to their
respective directory under Qt 5.14.2 director. For example
Qt5Core_DIR:PATH=/home/isunni/Qt/5.14.2/gcc_64/lib/cmake/Qt5Core.

Unfortunately, when I run the build command (e.g. ninja -j6) I got some
error like this below:

In file included from
> /home/isunni/Qt/5.14.2/gcc_64/include/QtCore/qcalendar.h:48:0,
>                  from
> /home/isunni/Qt/5.14.2/gcc_64/include/QtCore/QtCore:37,
>                  from /home/isunni/dev/cpp/QGIS/src/gui/qgshelp.h:19,
>                  from
> /home/isunni/dev/cpp/QGIS/src/providers/postgres/qgspgnewconnection.h:21,
>                  from
> /home/isunni/dev/cpp/QGIS/src/providers/postgres/qgspgnewconnection.cpp:22:
> /home/isunni/Qt/5.14.2/gcc_64/include/QtCore/qstringview.h: In
> instantiation of ‘constexpr QStringView::QStringView(const Pointer&) [with
> Pointer = const char16_t*; typename
> std::enable_if<QtPrivate::IsCompatiblePointer<Pointer>::value, bool>::type
> <anonymous> = 1]’:
> /home/isunni/Qt/5.14.2/gcc_64/include/QtCore/qstringbuilder.h:378:71:
> required from here
> /home/isunni/Qt/5.14.2/gcc_64/include/QtCore/qstringview.h:201:53: error:
> ‘lengthHelperPointer’ was not declared in this scope
>          : QStringView(str, str ? lengthHelperPointer(str) : 0) {}
>                                   ~~~~~~~~~~~~~~~~~~~^~~~~


It seems, it still refers to the system installed Qt (5.9), but I am not
sure which one since I already set the Qt5*_Dir to QT 5.14.2 and the
CMAKE_PREFIX_PATH is also set to /home/isunni/Qt/5.14.2/gcc_64 (where my Qt
5.14.2 located)

Is there a parameter that I should update beside the Qt5*_Dir to make it
work? Or is there any library or package that I need to install
additionally?

I am using Ubuntu 18.04 and can build QGIS using the system installed Qt
(5.9) fine.

Thanks!

NB: Here is my CMakeCache:
https://gist.github.com/ismailsunni/c61b6b51c83753df39fea67b5e848b80

-- 
Ismail Sunni
Software Engineer
ismailsunni.id
ismailsunni.wordpress.com
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