Qt CMake Semantic Issue

MCey

Hi
I am having very annoying problems with even fresh project on Qt with CMake. I have no idea what cause such warnings and errors below:

mainwindow.cpp:6: error: allocation of incomplete type 'Ui::MainWindow'
mainwindow.h:7: forward declaration of 'Ui::MainWindow'
mainwindow.cpp:8: error: member access into incomplete type 'Ui::MainWindow'
mainwindow.h:7: forward declaration of 'Ui::MainWindow'
mainwindow.cpp:13: warning: deleting pointer to incomplete type 'Ui::MainWindow' may cause undefined behavior
mainwindow.h:7: forward declaration of 'Ui::MainWindow'

All of them seems as semantic issue and program could be run.
What is wrong with these errors!

jsulm

@MCey said in Qt CMake Semantis Issue:

All of them seems as semantic issue and program could be run

Could be run? How? These are compiler errors!
Do you include "ui_mainwindow.h" in mainwindow.cpp?

aha_1980

@MCey
the annotations may come from the Clang Code Model.

do they go away after successful build (and maybe project reload)?

@jsulm nowadays the Clang warnings/errors appear in the Issues window too...

ambershark

@MCey Can we see your CMakeLists.txt ... this looks like you didn't moc your interface objects.

Without seeing your cmake, here's a couple ideas:

Make sure you have set(CMAKE_AUTOMOC ON)
Use the macro to wrap your UI files:

qt5_wrap_ui(UI_SRC
   ui/MainWindow.ui
)

...

add_executable(${PROJECT_NAME} ${SRC} ${UI_SRC})

Don't just copy that verbatim though. You need to adjust to your cmake, or share it and I'll help you. :)

Edit: I missed this part:

All of them seems as semantic issue and program could be run.

If the program runs then it isn't a cmake issue then it's probably just the parser that the above posts talk about.

qtcat

Im having exactly this problem too.
Im creating a new project from scratch, and the first thing i see are errors :D

I assume there will be more users that encouter this error - so i ask:
How can we get rid of this?

jsulm

@qtcat Did you build your app?
ui_mainwindow.h is a file which is generated during build. If it is not yet there (because you did not yet build), QtCreator will show this errors/warnings because it does not know what Ui::MainWindow, which comes from that generated file, is.