How to use existing QMake project (.pro project file) as "external project" in CMake?

Question

Is there a concise doc or example for how to use an existing QMake project with .pro project file as an "external project" in CMake? This can somewhat be done in qtcreator by marking one project as dependency of another, but it would be nice to define it more explicitly with the ExternalProject() CMake syntax.

related question: CMake: How to build external projects and include their targets

Answer 1

Something like this works. You can then edit the files from either qtcreator in main CMake project tree, OR from opening the .pro file; great for iterating quickly on QT widgets in SomeGarbageApplication that is part of large cmake build tree.

macro(DeclareProjectFiles  Tag  Filez)
######### Trick: use this syntax to make arbitrary files
#########             appear in IDE project. #######################
### Note: pass in the raw name of a list variable,
###   since it will get expanded here in this macro.
  add_custom_target(${Tag}_files  ALL
                    pwd
                    COMMAND ls -ltrh
                    COMMENT  " ${Tag} files thunk... got list: [ ${${Filez}} ]"
                    VERBATIM
                    SOURCES  ${${Filez}}
                   )    
endmacro()

    message(STATUS "QT_QMAKE_EXE is:  ${QT_QMAKE_EXECUTABLE}")

set(Z  SomeGarbageApplication)
file(GLOB  ${Z}_Files
            ./*.cpp
            ./*.h
            ./*.ui
            ./*.pro
            ./*.png
            ./*.jpg)

DeclareProjectFiles( ${Z}_grbg  ${Z}_Files )

add_custom_target(${Z}_pro  ALL)

set(ExtraQMakeArgs  -r -spec linux-g++ CONFIG+=release)

# note: use killall because this can/will fail if the exe is running
#       But, need || true to not fail build when it's not running. 

add_custom_command(TARGET  ${Z}_pro
                   COMMAND  killall
                   ARGS     -q -9 -v ${Z} || true
                   COMMAND  ${QT_QMAKE_EXECUTABLE}
                   ARGS     -query
                   COMMAND  ${QT_QMAKE_EXECUTABLE}
                   ARGS     ${CMAKE_CURRENT_SOURCE_DIR}/${Z}.pro ${ExtraQMakeArgs}
                   COMMAND  make  ${Z}
                   ARGS     -j4
                   COMMAND  cp
                   ARGS     ${Z} ${CMAKE_CURRENT_SOURCE_DIR}/${${Z}_config}  ${CMAKE_BINARY_DIR}/bin/
                   WORKING_DIRECTORY  ${CMAKE_CURRENT_BINARY_DIR}
                   VERBATIM
                   )    
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