CMake Knowledge Base

CMake is a build-system generator: you describe your project once in CMakeLists.txt, and CMake emits the native build files (Makefiles, Ninja, Visual Studio, Xcode) for whatever platform you're on. These docs cover modern, target-based CMake (3.15+) — the target_* style that replaced the old global-variable approach — from first project to dependencies, testing, and the advanced bits.

How this is organised

Roughly in learning order: Intro → Basics → Targets is the core you use every day; Dependencies, Organization, Advanced, and Testing are the layers you add as projects grow. Each folder is self-contained — follow the cross-links.

Sections

	Section	What it covers
	Introduction	What CMake is, installing it, your first project
	Basics	CMakeLists.txt structure, variables, commands, build types, presets
	Targets	Executables, libraries, target properties, linking
	Dependencies	find_package, FetchContent, ExternalProject
	Project Organization	Multi-directory layouts, add_subdirectory, modern patterns
	Advanced	Generator expressions, functions/macros, find modules, custom commands
	Testing	CTest basics and integrating tests into the build

Suggested reading paths

• New to CMake: Introduction → Basics → Targets. Enough to build a real app.
• Pulling in a library: find_package → FetchContent, then linking.
• Scaling a project: Subdirectories → Multi-Directory → Best Practices.

Quick reference

CMakeLists.txt essentials

cmake_minimum_required(VERSION 3.15)
project(MyProject VERSION 1.0 LANGUAGES CXX)

add_executable(myapp main.cpp)
add_library(mylib STATIC lib.cpp)

target_link_libraries(myapp PRIVATE mylib)          # who depends on whom
target_include_directories(myapp PRIVATE include/)  # scoped to this target
target_compile_features(myapp PRIVATE cxx_std_17)   # request a standard

find_package(Threads REQUIRED)

Build workflow

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release   # configure
cmake --build build -j                           # build (parallel)
ctest --test-dir build                           # test
cmake --install build --prefix /usr/local        # install

Conventions used across these docs

• Examples target CMake 3.15+ and the modern target-based style (target_* over global set()).
• The golden rule throughout: set properties on targets with PRIVATE/PUBLIC/INTERFACE scope, not globally.
• Admonitions flag the important bits: info context, tip guidance, warning/danger foot-guns.