[cmake-developers] cmake automoc breaks kde

[Stephen Kelly]

Alexander Neundorf wrote:

>> You said that you can't detect this case, but why do you have to? Isn't
>> there already a check for the Q_OBJECT macro in the cpp file? Wouldn't
>> the logic be 'if the <basename>.moc file is included but there is no
>> Q_OBJECT in the header, then moc the <basename>.h and put the result in
>> <basename>.moc', or does that conflict with another rule?
> 
> I'll put some more work in it over the weekend.
> Probably something like this should work.
> Or "if it's not my own .moc-file, never assume it's the .moc-file from
> another cpp-file (end of story here with Qt5), but try whether it could be
> the moc- file from a header".
> 


Please make the behaviour difference not determined by Qt4 vs Qt5 but by a 
variable.

That is, please make:

find_package(Qt4)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTOMOC_STRICT ON)

behave with what you call the 'Qt5' behaviour, and 

find_package(QtCore 5)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTOMOC_STRICT OFF)

behave with what you call the 'Qt4' behaviour.

That is, introduce a CMAKE_AUTOMOC_STRICT variable to control which mode the 
automoc stuff works with, and have a different default between Qt4 and Qt5, 
but allow overriding that default.

Porting to Qt5 (for KDE at least) needs to eb a multi-step process for 
applications depending on kdelibs (and this feature). I think it needs to be 
possible to run automoc in non-strict mode with Qt5. 

Thanks,

Steve.