[CMake] QT4_WRAP_CPP and Implicit Dependencies

[Clinton Stimpson]

If you run moc on Main.h, which includes Dum.h, moc doesn't even open "Dum.h" to scan its contents.
That tells me there is no way that moc would be required to rescan Main.h if Dum.h is modified.

Clint


On Oct 10, 2012, at 10:32 PM, Miller, Frank wrote:

> Greetings,
> 
> Suppose we have a header file, Dum.h, that is included by another header
> file, Main.h, and Main.h needs to be processed with the qt moc tool.
> When Dum.h changes, should we rerun moc on Main.h?
> 
> QMake says yes. CMake, using QT4_WRAP_CPP, says no.
> 
> I am inclined to believe qmake on this one. However, I have yet to think
> of a way to break a build by not rerunning moc. Is this a problem?
> 
> Please pardon me if you think this question is in the wrong forum. I am
> asking here because I know there are a lot of qt users in this community
> and qmake is clearly not doing anything wrong.
> 
> Here is a simple example:
> 
>    === CMakeLists.txt ===
>    cmake_minimum_required( VERSION 2.8.0 )
>    project( mocdep )
>    find_package( Qt4 REQUIRED )
>    include( ${QT_USE_FILE} )
>    include_directories( ${CMAKE_BINARY_DIR} )
>    QT4_WRAP_CPP( mocdep_MOCSOURCES Main.h )
>    add_executable( mocdep Main.cpp ${mocdep_MOCSOURCES} Main.h )
>    target_link_libraries( mocdep ${QT_QTCORE_LIBRARY} ${QT_QTGUI_LIBRARY} )
> 
>    === mocdep.pro ===
>    HEADERS = Main.h Dum.h
>    SOURCES = Main.cpp
> 
>    === Dum.h ===
>    #pragma once
> 
>    === Main.h ===
>    #pragma once
>    #include "Dum.h"
>    #include <QMainWindow>
> 
>    class MainWindow : public QMainWindow
>    {
>        Q_OBJECT
>    };
> 
>    === Main.cpp ===
>    #include "Main.h"
>    #include <QApplication>
> 
>    int main( int argc, char * argv[] )
>    {
>        QApplication app(argc, argv);
> 
>        MainWindow mainWindow;
>        mainWindow.show();
> 
>        return app.exec();
>    }
> 
> Frank
> 
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