Changing from Qt4 to Qt5: QtGui/QAction: No such file or directory in generated ui_ file

Question

I have to make sure my project builds both in Qt 4 (I have 4.7 installed) and Qt 5 (I have 5.5).

For that, in many places I have, in pro file:

NOT_QT_4 {
     QT += widgets
} else {
    #Nothing specific
}

and in code:

#ifdef NOT_QT_4
    #include <QtWidgets>
#else
    #include <QtGui>
#endif

Yet every time I switch build from Qt 4 to Qt 5, I get an error:

ui_somefile.h:14: error: QtGui/QAction: No such file or directory
 #include <QtGui/QAction>
                         ^

This is in a ui_ file generated from a form created using the Qt Designer... so I can't put the defines that I use in normal code.

It is extremely difficult to get it to build: Build->Clean All, erase every single file on disk (debug, release, make*, ui_*), Build->Clean All again (useless of course), run qmake, build again ...
still I have to do it repeatedly because the ui_ file seems to regenerate with defective info.

Since I have to make sue every commit builds in both Qt4 and Qt5 versions, I have to do this a lot right now...

How can I make it build correctly in Qt5 - and alternatively how can I clean that particular portion of the build easily ? (a clean build takes several minutes... giant project...)

Answer 1

I recommend that you put those ui_*.h files in a different location, such that the results could be different and compile uniquely between QT versions.

NOT_QT_4 {
   UI_HEADERS_DIR = foo
} else {
   UI_HEADERS_DIR = bar
}