CODEWITHSUNDEEP
c++cmakeheader
solosito
solosito

Reputation: 11

CMakeList for just headers project and use it in another project

I am having some problems for creating the CMakeList for my project. I have the following structure:

ProjectAB
|
|--- include
|     |--- A.h
|     |--- B.h
|
| --- CMakeList.txt

Project1
|
|--- include
|     |--- src1.h
|
|--- src
|     |--- src1.cpp (#include "src1.h"; #include "A.h"; #include "B.h")
|
| --- CMakeList.txt

ProjectAB is just composed by headers, so I have been reading in the CMake guides and some other sources (link) and finally I wrote the following CMakeList for it:

cmake_minimum_required(VERSION 3.6.1)

project(lib_projectAB VERSION 1.0.0 LANGUAGES CXX)

add_library(projectAB INTERFACE)

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)

target_include_directories(projectAB 
    INTERFACE
        A.h
        B.h
)

Now I want to use the headers of the ProjectAB in the Project1. I have to install them because of unrelated reasons. I am not sure how the CMakeLists for both projects should look like.

I thought of this for the Project1:

cmake_minimum_required(VERSION 3.6.1)

project(lib_project1 VERSION 1.0.0 LANGUAGES CXX)

add_subdirectory(src)

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../projectAB/include)

add_library(project1
    STATIC
        src1.h
        src1.cpp
)

target_link_libraries(project1
    PUBLIC
        third_party_LIBRARIES
        lib_projectAB
)

install(
    FILES
        src1.h
        A.h
        B.h
    DESTINATION
        .
)

But it is not elegant and neither working.

How would be the proper way for doing this?

Upvotes: 1

Views: 1608

Answers (1)

Dutow
Dutow

Reputation: 5668

First, you are marking the wrong directory as the location of include files:

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../projectAB)

As according to your directory tree, these files are located in projectAB/include, not in projectAB directly.

Depending on where the CMakeLists for projectAB is located, you could have a similar problem there.

Also, you aren't using the CMakeLists for projectAB for building project1, but you should specify include directories there, not actual header files - and the simple include_directories call is also unneccessary: by specifing interface include directories for a target, anything depending on that target will add those directories to it's include path.

Another problem is that your project1 doesn't actually depend on projectAB - that's why you try to modify the include path there manually.

Ideally you would would want to follow two possible paths:

  • If the two projects are mostly developed separately, you could use the find package functionality of cmake for project1 to find projectAB
  • IF they are usually developed together (based on the layout, I am assuming this is the case), you should add the projectAB cmakelists to project1 using add_subdirectory. After that, the projectAB target will be available, and you can add it as a dependency to project1.

Unfortunately, while it's possible to use add_subdirectory to add a directory which isn't the child of the current directory, it isn't recommended.

So to follow this approach, you would have to either:

  • move projectAB to be a subdirectory of project1
  • or add a "root" CMakeLists, which adds first projectAB, then project1 using add_subdirectory - which again would mean that project1 would use the projectAB target.

Upvotes: 1

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