CODEWITHSUNDEEP
c++cmakefindpackage
evolved
evolved

Reputation: 2210

cmake find_package relative path in CMakeLists.txt subfolder

I have the following file structure and would like to use a cmake config file MYLIBConfig.cmake which is used by all CMakeLists.txt files in the projects to include headers located in a folder include on the top level. 

MYLIBConfig.cmake
include/
    header_a.h
    header_b.h
src/
    project_a/
        CMakeLists.txt
        main.cpp
    project_b/
        CMakeLists.txt
        main.cpp

A CMakeLists.txt containts the following:

cmake_minimum_required(VERSION 3.14)

find_package(MYLIB REQUIRED PATHS ${CMAKE_CURRENT_SOURCE_DIR}/../../)

project(projecta)

set(CMAKE_CXX_STANDARD 17)

add_executable(projecta main.cpp)

message(${MYLIB_INCLUDE_DIRS}) # Outpus /include/ which is the problem. Should be a relative path to the include folder

target_include_directories(${PROJECT_NAME}
        PRIVATE
            ${MYLIB_INCLUDE_DIRS}
        )

The MYLIBConfig.cmake has currently the following content:

cmake_minimum_required(VERSION 3.14)

#message(${PREFIX})

set(MYLIB_INCLUDE_DIRS ${CMAKE_PREFIX_PATH}/include/)

With this setup, I am not able to include the headers in my main.cpp files using #include "header_a.h" because they are not found.

The problem is that I don't know if my usage of find_package is correct because the set variable MYLIB_INCLUDE_DIRS is just /include/ when I use message(message(${MYLIB_INCLUDE_DIRS}) inside the CMakeLists.txt. Is there a cmake variable that I can use in the MYLIBConfig.cmake file that sets a path which is relative to the "currently active" CMakeLists.txt? Or is there another way to achieve a working include using a config file? I know that I could just use a relative path inside the target_include_directories of every CMakeLists.txt but I would like to use a config file to have the flexibility of changing the include folders and possibly set more variables. In the config file I also tried to use ${CMAKE_PREFIX_PATH} and ${CMAKE_CURRENT_SOURCE_DIR} but these variables did not work either.

EDIT

Another way I think it could work is when the MYLIB_INCLUDE_DIRS would result in a global path. Would this be the appropriate way? And how could this be done?

Upvotes: 1

Views: 1790

Answers (1)

Lasall
Lasall

Reputation: 480

You can get the global path in MYLIBConfig.cmake with CMAKE_CURRENT_LIST_DIR:

set(MYLIB_INCLUDE_DIRS ${CMAKE_CURRENT_LIST_DIR}/include/)

Or if you want a relative path to the currently processed source you can get it accordingly with file:

file(RELATIVE_PATH MYLIB_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR} ${CMAKE_CURRENT_LIST_DIR}/include/)

Upvotes: 2

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