Standalone build is broken

[rainerdeyke]

Trying to build corosio as a standalone library doesn't work for me because it cannot find capy. Looking at the CMakeLists.txt, it looks like it doesn't even try to look for capy. I have successfully built and installed capy, so corosio just needs to find my installed copy of capy. I am not using CMake for my own program so I can't just use FetchContent to make both capy and corosio available to my program.

[pgit]

Same here, I think this got broken by the addition of FetchContent_Declare for capy and corosio:

corosio/cmake/CorosioBuild.cmake

Lines 12 to 15 in 7c636ac

	# Resolve build dependencies: sibling Boost libraries when inside a
	# boost tree, and Threads. Capy (Boost::capy) must be provided by
	# the consumer — CMake resolves the target reference at generation
	# time, so declaration order does not matter.

As a workaround, you can "inject" capy when building corosio

find_package(boost_capy REQUIRED)
if(TARGET Boost::capy AND NOT TARGET boost_capy)
    add_library(boost_capy INTERFACE IMPORTED GLOBAL)
    set_target_properties(boost_capy PROPERTIES INTERFACE_LINK_LIBRARIES "Boost::capy")
endif()

and inject that file by adding

-DCMAKE_PROJECT_boost_corosio_INCLUDE=.devcontainer/inject_capy.cmake

But I agree that there should be a straightforward way to build first capy, then corosio.

[sgerbino]

This is an intended change, to consume with CMake we recommend the following:

include(FetchContent)

FetchContent_Declare(capy
    GIT_REPOSITORY https://github.com/cppalliance/capy.git
    GIT_TAG develop
    GIT_SHALLOW TRUE)
FetchContent_Declare(corosio
    GIT_REPOSITORY https://github.com/cppalliance/corosio.git
    GIT_TAG develop
    GIT_SHALLOW TRUE)

FetchContent_MakeAvailable(capy corosio)

target_link_libraries(my_app Boost::corosio)

Eventually, this dependency should be handled by package management whether it's conan, vcpkg, or hunter. Or just handled gracefully in the boost superproject.