Creating a Makefile is challenging:

• Must list all prerequisite include files
• Straightforward for an in-source build, more difficult for an out-of-source build
• Note: Out-of-source builds are preferred
• Make is Turing Complete, but conditional (e.g., if-statements) and repetition (e.g., for-statements) statements have an unfamiliar syntax
• Limited internal and external libraries and additional support software

CMake

• CMake is a build-file generator and can generate build files for many platforms and environments
• cmake --help shows a list of Generators
• Related tools: ctest, cpack
• Has both command-line and GUI tools
• Under constant improvement
• Works well on Linux, macOS, and with Windows MSVC

Build languages are declarative

• As opposed to imperative
• make
• nmake
• cmake
• Ant

Abstraction levels get higher over time

• set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++17")
• set(CMAKE_CXX_STANDARD 17)
• target_compile_features(${TARGET_NAME} PRIVATE cxx_std_17)
• More variation, history, and discussion at How to enable C++17 in CMake

There is always more to learn

• The cmake-provided target, install, has a variation, install/strip
• make install
• make install/strip
• Another Example: Download and install external source vs file(DOWNLOAD ...)

Multiple structural design decisions to make

• srcML build file structure
• Full View
• Build file structure follows source file tree structure
• Alternative: A single large CMakeLists.txt that knows the tree structure of the source (and prevents any change to that structure)

Types of CMake Files

• Full View
• CMakeLists.txt - The default name, found in the top directory and often in subdirectories
• CMakePresets.json JSON file with presets to use with the CMake option --preset. Much of the specific build configuration has moved from the CMakeLists.txt into this file.
• CMakeUserPresets.json JSON file with personal presets to use with the CMake option --preset. It is not committed to the repository, and it is developer-specific.
• toolchain-gcc CMake commands for a specific platform
• macos-libarchive.cmake Separates out specific processing from CMakeLists.txt
• srcMLConfig.cmake.in - Input for generating files for other CMake projects to be able to use find_package(srcML) (as with find_package(LibXml2 REQUIRED))
• CTestConfig.cmake - CDash configuration
• wix.cpack.cmake CPack configuration for a Windows WiX installer (generates an MSI installer). Custom naming convention so that installers can be loaded automatically.
• vcpkg.json JSON file with list of dependencies for vcpkg builds. The primary purpose of vcpkg is to easily allow Windows developers to use open-source libraries in their applications. Integrates easily into CMake builds.

Build File Comparison: srcML

Summation

• Always use a build tool to build programs. Do not use direct entry of compiler commands. Build your knowledge into the build file instead of having to remember.
• Things don't always work the same on all platforms, so you have to experiment
• While CMake and other tools may be difficult, the main problem is that building code into an executable or installer has many difficult situations
• In some ways, build files are static and dynamic. They tend to be created and work for a long time but must be maintained as the platforms we build on and for change.