No exported target for msgpack-cpp

[wnts]

The CMakeLists.txt on the cpp branches does not install exported targets for use with find_package.

This is in contrast with the CMakeLists.txt on the c_master branch

msgpack-c/CMakeLists.txt

Lines 314 to 332 in 4f59b98

	CONFIGURE_PACKAGE_CONFIG_FILE (msgpack-config.cmake.in
	msgpack-config.cmake
	INSTALL_DESTINATION "${CMAKE_INSTALL_CMAKEDIR}"
	)
	INSTALL (EXPORT msgpack-targets
	FILE
	msgpack-targets.cmake
	DESTINATION
	"${CMAKE_INSTALL_CMAKEDIR}"
	)
	INSTALL (
	FILES
	"${CMAKE_CURRENT_BINARY_DIR}/msgpack-config.cmake"
	"${CMAKE_CURRENT_BINARY_DIR}/msgpack-config-version.cmake"
	DESTINATION
	"${CMAKE_INSTALL_CMAKEDIR}"
	)

[redboltz]

Thanks you for reporting the issue. @ygj6, could you check this?

[ygj6]

Exporting targets is to generate configuration files which used by find_package(). However, msgpack_cpp is a header-only library that cannot be processed by find_package(), so there is no need to export targets.

[wnts]

Providing a package configuration file with an exported target for header-only libraries is stil possible through INTERFACE libraries. (and provides for easy use of the library: finding correct include directory (if not installed to standard system prefix or include directories), propagate transitive dependencies, setting compiler options, etc...):

Usage:

project(SomeMsgpackCxxProject CXX)

find_package(msgpackcxx REQUIRED)

add_executable(${PROJECT_NAME} main.cpp)
target_link_libraries(${PROJECT_NAME} msgpackcxx)

I will set up a draft pull request with a preliminary proposal.