cppug-kl-1122

Code for the C++ User Group Kaiserslautern from November 2022.

CMake Documentation and References

For additional information on CMake, have a look at the following references:

• CMake's official documentation
• Modern CMake for C++ (also available on other online shops)
• Several YouTube talks:
  • CppCon 2017: Mathieu Ropert "Using Modern CMake Patterns to Enforce a Good Modular Design"
  • C++Now 2017: Daniel Pfeifer "Effective CMake"
  • CppCon 2018: Mateusz Pusz "Git, CMake, Conan - How to ship and reuse our C++ projects"
  • CppCon 2019: Craig Scott "Deep CMake for Library Authors"
  • Meeting C++ 2019: Deniz Bahadir "Oh No! More Modern CMake" (DANGER: See notes below)
  • Microsoft Developer: An Introduction to CMakePresets.json
  • CppCon 2021: Bret Brown "Modern CMake Modules"
  • CppCon 2022: Bill Hoffman "import CMake, CMake and C++20 Modules"
  • C++Now 2022: Bill Hoffman "Modules and More"

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NOTES:

• Don't override builtin CMake commands/functions. This is very error prone and generally considered bad practice.
• Don't use CMAKE_PROJECT_INCLUDE[_BEFORE] as described in the video. This CMake functionality is meant for injection not what it is used for in the talk.

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Using CMake Graphical User Interface

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PROJECT CONFIGURATION ONLY

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CMake comes with 2 graphical tools for configuring projects:

• ccmake is terminal based using ncurses.
• cmake-gui is based on the OS's window system using Qt.

These tools are extremely useful for exploring unknown project options and settings. The commands listed below for configuring a project are useable by both tools.

Using CMake Command-Line Interface

Configuring a project

Pre-Modern:

cd <build-dir>
cmake –D CMAKE_TOOLCHAIN_FILE=toolchain.cmake
      –D CMAKE_INSTALL_PREFIX=install
      –D CMAKE_INSTALL_MESSAGE=LAZY
      <path-to-source-dir>

Modern:

cmake –C build-config.cmake
      --toolchain toolchain.cmake
      -B <build-dir>
      -S <source-dir>

• -C is supported since CMake 3.0.
• --toolchain is supported since CMake 3.21. On older versions the toolchain file is set via -D CMAKE_TOOLCHAIN_FILE=<toolchain-file>.

Post-Modern:

cmake --preset <preset-name>
      -S <source-dir>

Presets are supported since CMake 3.19.

Building a configured project

Pre-Modern:

cd <build-dir>
make –j 8

Modern:

cmake --build build -j 8

• --build is supported since CMake 3.0.
• -j\|--parallel is supported since CMake 3.12. In previous version the option can be added by passing additional compiler arguments: -- -j 8.

Post-Modern:

cd <source-dir>
cmake --build –-preset <preset-name>

Build presets are supported since CMake 3.20.

Testing a built project

Pre-Modern:

cd <build-dir>
ctest --output-on-failure

Modern:

ctest --test-dir <build-dir> --output-on-failure

cd <source-dir>
ctest --preset <preset-name>

--test-dir and --preset are supported since CMake 3.20.

Installing a built project

Pre-Modern:

cd <build-dir>
make install

Modern:

cmake --install <build-dir>

--install is supported since CMake 3.15.

Wishful Thinking:

cd <source-dir>
cmake --install --preset <preset-name>