cmake + qt + visual studio: moc objects on build

Question

I am using cmake + qt + visual studio to work on a project. Problem I am having it that I would like visual studio to create new moc objects if I modify the QT ui files. If I just do a full build everything works file, but if I just modify something on the ui file it does not "auto moc" and I have to rebuild the whole project.

The cmake file I have is pretty simple:

cmake_minimum_required(VERSION 3.2)

set(CMAKE_VERBOSE_MAKEFILE ON)

project(main)

set(CMAKE_INCLUDE_CURRENT_DIR ON)

set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTOUIC ON)

find_package(Qt5Widgets)

file(GLOB CPP_FILES *.cpp)

add_executable(main ${CPP_FILES})
target_link_libraries(main Qt5::Widgets)
target_compile_features(main PUBLIC cxx_nullptr)

Does anyone know a way to get this to work (having visual studio to detect ui file modifications and "auto moc" the modified ui file)?

Answer 1

Start by replacing your file(GLOB ...) with explicitly listing out the files you want to include if you want proper dependency handling. This will also ensure the build is creating dependencies for the set of files you are expecting it to. This answer has more details about why you probably want to do this, aside from the reasons below.

The CMake documentation for AUTOUIC includes this statement:

If a preprocessor #include directive is found which matches ui_<basename>.h, and a <basename>.ui file exists, then uic will be executed to generate the appropriate file.

Can you confirm that your .cpp sources have #include directives that follow this pattern? In your file(GLOB ...) you are only capturing the .cpp files and not the .h files, so if you've only got the #include directives in the headers, AUTOUIC may not pick them up properly. It's been a while since I've used this and I can't recall if AUTOUIC would still find them if you only list the .cpp files and not the headers too in your add_executable() call, but it's something for you to try. You also may be facing a similar situation with AUTOMOC if you have headers which use the Q_OBJECT and Q_GADGET macros. So just explicitly list out your .cpp and .h files you give to add_executable() and see if that addresses your problem.