How to install an external project?

Code
11

Hi Florian,

Thanks! The CPACK_INSTALL_CMAKE_PROJECTS was the thing that I was missing, this was quite a journey!

I did some experimentation and it seems like that’s about all I needed actually; I was able to remove all of the target imports and exports and the packaging still worked.

Here’s what my files looked like:

Root / Superbuild CMakeLists.txt

cmake_minimum_required (VERSION 2.6)

project(SUPERBUILD_ROOT)

include(ExternalProject)

# ----------------------------------------------------------------------------------------------------------------------
# Set up our external projects
# ----------------------------------------------------------------------------------------------------------------------

ExternalProject_Add(extern
                    GIT_REPOSITORY "[extern's git repository]"
                    CMAKE_ARGS
                        -DCMAKE_INSTALL_PREFIX:PATH=${CMAKE_CURRENT_BINARY_DIR}/extern-install
)

ExternalProject_Add(Main
                    GIT_REPOSITORY "[main's git repository]"
                    CMAKE_ARGS
                        -DCMAKE_INSTALL_PREFIX:PATH=${CMAKE_CURRENT_BINARY_DIR}/Main-install
                    DEPENDS 
                        extern
)

# ----------------------------------------------------------------------------------------------------------------------
# Read the "binary directories" of both external projects
#
# CMake calls the build\extern-prefix\src\extern-build a "Binary directory", but it's really the directory where the VS Solution is, etc.
# I'd call these "build directories", to be honest...
# ----------------------------------------------------------------------------------------------------------------------

unset(BINARY_DIR)

#This function writes to a variable named BUILD_DIR... okay sure?
#It'll get clobbered twice so we have to save the result somewhere else.....
ExternalProject_Get_property(extern BINARY_DIR) 
set(externBuildDirectory ${BINARY_DIR})
message("extern's build directory is " ${externBuildDirectory})

unset(BINARY_DIR)

ExternalProject_Get_property(Main BINARY_DIR)
set(mainBuildDirectory ${BINARY_DIR})
message("Main's build directory is " ${mainBuildDirectory})

unset(BINARY_DIR)

# ----------------------------------------------------------------------------------------------------------------------
# Write these paths to CPACK_INSTALL_CMAKE_PROJECTS so that CPack will know to visit these projects for packaging
# ----------------------------------------------------------------------------------------------------------------------

# https://cmake.org/cmake/help/latest/module/CPack.html?highlight=cpack_install_cmake_projects#variable:CPACK_INSTALL_CMAKE_PROJECTS
#                       project build dir       proj name   build all components    "Directory" (??)
set(externProjectInfo   ${externBuildDirectory} "extern"    "ALL"                   "/")
set(mainProjectInfo     ${mainBuildDirectory}   "Main"      "ALL"                   "/")

# both of these go in one list
set(allProjectInfo ${mainProjectInfo} ${externProjectInfo})

message("CPACK_INSTALL_CMAKE_PROJECTS before append is " ${CPACK_INSTALL_CMAKE_PROJECTS})

# I think this variable has to be set before CPack is included.
set(CPACK_INSTALL_CMAKE_PROJECTS ${allProjectInfo})

message("CPACK_INSTALL_CMAKE_PROJECTS after append is " ${CPACK_INSTALL_CMAKE_PROJECTS})

# ----------------------------------------------------------------------------------------------------------------------
# Now include CPack (must be last)
# ----------------------------------------------------------------------------------------------------------------------

include(CPack)
set(CPACK_GENERATOR NSIS)

Extern (AKA Dep)'s CMakeLists.txt

cmake_minimum_required (VERSION 2.6)

project(SUPERBUILD_EXTERN)

message("Hello from the external repository's CMakeLists.txt!")

# Creates the executable with the listed sources and adds sources to the Solution Explorer
# (but you won't see extern.c in the root (superbuild) solution)
add_executable (extern_binary extern.c)

install (TARGETS extern_binary 
        RUNTIME DESTINATION "DirectoryForCmakeSuperbuild_Extern"
        )

Main’s CMakeLists.txt

cmake_minimum_required (VERSION 2.6)

project(SUPERBUILD_MAIN)

message("Hello from the main repository's CMakeLists.txt!")

# Creates the executable with the listed sources and adds sources to the Solution Explorer
# (but you won't see main.c in the root (superbuild) solution)
add_executable (main_binary main.c)

install (TARGETS main_binary 
         RUNTIME DESTINATION "DirectoryForCmakeSuperbuild_Main")

I suppose I’ll also put my github repositories here too, in case it helps anyone else:

One thing I’m wondering about though,

If it’s not possible to install using imported projects, what is the purpose of importing targets? Is it just for programs that don’t need to be packaged?

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