I think you're mixing up two different paradigms here.
As you noted, the highly flexible ExternalProject
module runs its commands at build time, so you can't make direct use of Project A's import file since it's only created once Project A has been installed.
If you want to include
Project A's import file, you'll have to install Project A manually before invoking Project B's CMakeLists.txt - just like any other third-party dependency added this way or via find_file
/ find_library
/ find_package
.
If you want to make use of ExternalProject_Add
, you'll need to add something like the following to your CMakeLists.txt:
ExternalProject_Add(project_a
URL ...project_a.tar.gz
PREFIX ${CMAKE_CURRENT_BINARY_DIR}/project_a
CMAKE_ARGS -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
)
include(${CMAKE_CURRENT_BINARY_DIR}/lib/project_a/project_a-targets.cmake)
ExternalProject_Get_Property(project_a install_dir)
include_directories(${install_dir}/include)
add_dependencies(project_b_exe project_a)
target_link_libraries(project_b_exe ${install_dir}/lib/alib.lib)