CMake include Boost Beast (header only)

Question

I want to include Boost Beast into my project. It's a header-only library. I have cloned the Beast repository into the same directory as my project.

I am using the following in CMake to include the header:

set(BEAST_INCLUDE_DIR ../beast/include)

include_directories(${BEAST_INCLUDE_DIR})

set(SOURCE_FILES ${BEAST_INCLUDE_DIR}/boost/beast.hpp ...)

add_library(my_lib ${SOURCE_FILES})

I'm including using the following (alongside other Boost includes):

#include <boost/beast.hpp>
#include <boost/asio/io_service.hpp>

But I get the following error:

fatal error: boost/beast.hpp: No such file or directory

Do I need to do something special to include another "boost" directory? The path of the header is:

beast/include/boost/beast.hpp

Answer 1

I would suggest creating an interface library for Beast which you can then add as a dependency to your library.

Create interface library for Beast:

add_library(boost_beast INTERFACE)

target_include_directories(boost_beast
                           SYSTEM
                           PUBLIC
                           "${CMAKE_CURRENT_LIST_DIR}/../beast/include")

Note in the call to target_include_directories I've specified:

• SYSTEM : tells the compiler the directories are meant as system include directories
• PUBLIC : tells the compiler the directories should be made visible to both the target itself ( boost_beast ) and the users of the target (your library)

Add Beast as a dependency to your library:

Then you can add boost_beast as a dependency to your library:

add_library(my_lib ${SOURCE_FILES})

target_link_libraries(my_lib boost_beast)

At this point, my_lib will transitively have the Boost Beast include directory available to it.