cmake_minimum_required(VERSION 3.11...3.14) project(DummyImport CXX) include(FetchContent) get_filename_component(GIT_REPOSITORY_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/../../.. ABSOLUTE) FetchContent_Declare(json GIT_REPOSITORY ${GIT_REPOSITORY_DIRECTORY} GIT_TAG HEAD) FetchContent_GetProperties(json) if(NOT json_POPULATED) FetchContent_Populate(json) add_subdirectory(${json_SOURCE_DIR} ${json_BINARY_DIR} EXCLUDE_FROM_ALL) endif() add_executable(with_namespace_target main.cpp) target_link_libraries(with_namespace_target nlohmann_json::nlohmann_json) add_executable(without_namespace_target main.cpp) target_link_libraries(without_namespace_target nlohmann_json)