CMake Case Studies

General

• Use latest CMake
• Find dependecies - find_package. Be careful with add_subdirectory and FetchContent
• Prepare for FetchContent users - manually namespace targets, make possible to disable packaging rules.
• Do not GLOB for sources.
• GenerateExportHeader - works for single library type.
• Put in CMakeLists.txt exactly what is necessary to produce a working build.
• Portability can lead to combinatorial explosion. Consider cmake presets

Create build targets

• add_executable - create an executable target
• add_library - create a library target

Working with targets

• target_sources - add source files to target
• target_include_directories - add include directories to target
• target_compile_options - add compile options to target
• target_link_libraries - add libraries or linker flags to target
• PRIVATE, PUBLIC, INTERFACE

Additional target properties

• target_compile_definitions
• target_compile_features
• target_link_directories
• target_link_options
• target_precompile_headers

Work with properties

• get_target_property
• set_target_properties
• function
• cmake_parse_arguments
• generator-expressions
• add_custom_command

Working with variables

• Set a normal variable
• Setting a cache entry

Module File

• CMAKE_MODULE_PATH
• FindOracle.cmake file
• Environment variable used
• https://github.com/SOCI/soci/blob/master/cmake/modules/FindOracle.cmake
• find_path - include path. Store result in Oracle_INCLUDE_DIR. mark_as_advanced to hide it from GUIs
• find_library . Store result in Oracle_LIBRARY
• find_program to find client programs.
• execute_process to call external program i.e. get the version.
• Check received variables using FindPackageHandleStandardArgs
• Create target Oracle::Oracle

  if (NOT TARGET Oracle::Oracle)
   add_library(Oracle::Oracle UNKNOWN IMPORTED)
   set_target_properties(Oracle::Oracle PROPERTIES
      IMPORTED_LOCATION "{Oracle_LIBRARIES}"
      INTERFACE_INCLUDE_DIRECTORIES "{Oracle_INCLUDE_DIRS}")
  endif()
  

• Add default include directories

C++20 modules

• import CMake; C++20 Modules
• Using CMake with C++20 modules

• Online Example

• Static checks with CMake/CDash - iwyu, clang-tidy, lwyu, cpplint and cppcheck

References

• import CMake: // 2023 State of C++20 modules in CMake - Bill Hoffman - CppNow 2023
• The Challenges of Implementing C++ Header Units: C++ Modules - Daniel Ruoso - CppNow 2023
• CMake: A Case Study - Hans Vredeveld - ACCU 2023
• Things I Learnt While Trying to Avoid Becoming a CMake Expert - CB Bailey - ACCU 2022
• Modern CMake Best Practices for Library Authors by Alex Reinking - San Diego C++ Meetup 7/11/2023
• SD C++ Meetup 2023
• https://github.com/alexreinking/sdcppmu-diffuse
• Building a Dual Shared and Static Library with CMake
• https://github.com/ComicSansMS/cpp_modules_includes