An introduction to the build pipeline, and how we can orchestrate it manually

Before working with CMake, it's useful to understand the tools it orchestrates. This lesson guides you through setting up a C++ toolchain.

Building C++ Programs

Walking through the steps of the C++ compilation process, from source code to machine code.

The Compilation Pipeline

The linker's role in the build process, how it resolves symbols to combine object files, and how to troubleshoot common errors.

Object Files and the Linking Process

The difference between static and dynamic libraries, how to create them, and the trade-offs between them.

Static and Shared Libraries

The C++ Build Process

Recommended approaches for managing large projects and the libraries that they depend on

Learn how to structure your C++ projects for scalability and maintainability, from basic directory layouts to managing multiple modules.

Organizing a C++ Project

Learn to manage third-party libraries in C++, covering include/library paths, static vs. shared libraries, versioning, and platform differences.

Managing Libraries and Dependencies

An introduction to traditional build tools like Makefiles and IDE projects, highlighting the maintenance, scalability, and cross-platform challenges that result

Automated Build Systems and Their Limitations

Project Structure and Dependency Management

Setting up CMake and creating your first project

An introduction to CMake, the cross-platform, open-source meta-build system that solves the core challenges of C++ project management.

Why CMake?

A step-by-step guide to installing CMake. We'll explore command-line, GUI, and IDE workflows, and how to configure your compiler.

Setting Up a CMake Environment

Creating the bare minimum `CMakeLists.txt` file and build up to a project with an executable and a library, learning the fundamental commands along the way.

Writing a CMakeLists File

Learn the two-stage process of building a CMake project. This lesson covers configuring, generating, building, running, and troubleshooting common errors.

Building and Running CMake Projects

Learn how to organize large C++ projects in CMake using subdirectories and the `add_subdirectory()` command to create modular, maintainable builds.

CMake Project Structure and Subdirectories

Introducing CMake

Exploring CMake's programming features, caching mechanisms, and interactions with the file system

A primer on the fundamental building blocks of the CMake language: variables, string interpolation, and logging messages.

CMake Variables and Logging

Discover the CMake Cache, the mechanism for storing persistent user-configurable options, and learn how to create and manage cached variables.

The CMake Cache

Exploring CMake's command syntax and its list data type, including how to create, manipulate, and use lists in your projects.

CMake Commands, Arguments, and Lists

Transform your static build descriptions into dynamic scripts with CMake's control flow commands, if() and foreach().

CMake Conditionals and Loops

Exploring CMake's `file()` command, covering how to read, write, copy, and glob files, and how to manipulate paths.

Working with the File System

Learn to create reusable logic with CMake functions and macros, and how to organize them into modules for clean, scalable build systems.

Modularizing CMake Code

CMake Language and Fundamentals

Learn more about targets, and how their properties and links are the foundation of modern CMake

Learn to work with target properties - understanding their purpose, setting and updating them, and retrieving them when your build requires it

Target Properties

Learn about target types, and how the `PUBLIC`, `PRIVATE`, and `INTERFACE` keywords control how properties are shared.

Relationships Between Targets

Discover how CMake's `target_link_libraries()` command builds a dependency graph, and how it uses this graph to automatically manage transitive dependencies and link order.

Indirect Relationships and the Dependency Graph

Learn to use abstract target types like `INTERFACE`, `ALIAS`, and `IMPORTED` to model complex project needs, organize build properties, and integrate pre-compiled binaries.

Using `INTERFACE`, `ALIAS`, and `IMPORTED` Libraries

Adding support for user-configurable library types and an initial introduction to target installation.

Using Shared Libraries

Targets and Dependencies

Learn how to manage multiple build configurations within the same project, and how to create scripts that adapt to the environment

Learn how CMake manages different build configurations like Debug and Release, the difference between generator types, and how to apply settings conditionally using modern techniques.

Build Configurations (Debug, Release, etc.)

Learn the tools and patterns needed to write portable CMakeLists.txt files that work seamlessly across platforms and compilers

Cross-Platform Configurations

Learn to write architecture-aware CMake scripts for 32/64-bit systems and Apple's Universal Binaries (Intel/ARM).

Handling Different Architectures

Learn to build for different operating systems and architectures using CMake's cross-compilation support and toolchain files.

Cross-Compilation and Toolchain Files

Platforms and Build Configurations

Learn how to add external libraries to our build, and how to create our own packages for others to use

Learn to find and use pre-installed libraries with `find_package()`, understanding Module vs. Config mode and the power of imported targets

Finding Dependencies using `find_package()`

Learn how to make your libraries consumable by other projects using CMake by turning your build-tree into a distributable install-tree.

Creating a Consumable Package

Learn how to consume a CMake package you've installed, completing the producer-consumer cycle. We'll cover using `find_package()` and how to point CMake to your library's location

Using Installed Packages

Learn how to create self-contained, reproducible builds by fetching dependencies from source using `FetchContent()` and `ExternalProject_Add()`.

Fetching External Dependencies

Creating and Consuming Packages

Integrating the vcpkg and Conan package managers to handle external dependencies

Learn to manage C++ dependencies effortlessly with the vcpkg package manager and its seamless CMake integration using toolchain files and manifests.

Integrating CMake and vcpkg

Learn the day-to-day commands for managing dependencies with vcpkg and how to guarantee reproducible builds using baselines and version overrides

vcpkg Commands and Versioning

Combine vcpkg with CMake's cross-compilation capabilities. Learn to use triplets to target different architectures and chain-load toolchain files

Cross-Compiling with vcpkg

Discover Conan, the binary-first C++ package manager, and learn how to integrate it with CMake using profiles and lockfiles for fast, reproducible builds.

Using Conan with CMake

Learn to cross-compile C++ projects with Conan, using build and host profiles to manage dependencies for different platforms.

Cross-Compilation with Conan

Package Managers

Introducing presets, allowing us to simplify our workflow and share common configurations across our team

Learn the fundamentals of CMake Presets. This lesson introduces `CMakePresets.json` to simplify complex build commands.

CMake Presets

Learn to structure your CMake presets with inheritance and customize them for your local environment using `CMakeUserPresets.json`.

User Presets and Inheritance

Learn to make your CMake presets portable by using environment variables and conditional logic to adapt to different machine configurations.

Environment Variables and Conditional Presets

Learn how to extend the build process beyond simple compilation by integrating external tools and custom commands

Learn how to use generator expressions `$<...>` for build-time conditional logic.

Generator Expressions and Conditional Logic

Learn how to attach commands to specific points in a target's build lifecycle using `add_custom_command(TARGET)` for tasks like post-build file copying.

Integrating Tools with `add_custom_command()`

Learn to integrate code generators like Protobuf into your build process using `add_custom_command()`, creating automated file-level dependencies in CMake.

Generating Files with Protobuf and `add_custom_command()`

Custom Commands

An introduction to automating common workflow chores by creating custom targets

Learn to create standalone, non-code targets using add_custom_target() for utility tasks like code formatting and documentation generation.

Custom Targets and Build Utilities

Using the Clang-Format tool to automatically enforce a consistent coding style, and integrating it into our build using a custom CMake target

Using Clang-Format

An introduction to file sets and the `target_sources()` command, allowing us to manage our header files in a more controlled way

Using File Sets

A step-by-step guide to integrating Doxygen into your CMake build process for automated C++ documentation.

Generating Documentation with Doxygen

Custom Targets

Integrate automated tests into a CMake project using CTest, GoogleTest, and GoogleMock

Learn the fundamentals of automated testing in C++ with CTest. Create your first test suite, register tests with `add_test()`, and run them with the `ctest` command.

Automated Testing and CTest

Learn to refactor manual C++ tests into a professional test suite using the GoogleTest framework, managed by vcpkg and integrated with CTest.

Integrating GoogleTest with CMake

Learn to use a wide range of assertions, write data-driven parameterized tests, and isolate dependencies with Google Mock.

Assertions and Parameterized Tests

Learn how to isolate dependencies that our project uses, and then how to replace those dependencies at test time using Google Mock.

Dependency Injection and Mocking

Learn the standard pattern for testing application logic by refactoring it into a linkable library

Testing Executables

Move beyond individual tests to manage a full test suite. Learn to organize tests, run tests in parallel, filter by labels, and measure our code coverage

Managing a Test Suite

Automated Testing

Using static and dynamic analysis in CMake projects to automatically detect memory bugs, performance issues, and problematic code

Learn to find memory bugs at runtime by integrating AddressSanitizer (ASan) into a CMake project

Using AddressSanitizer (ASan)

Adding benchmarks to our build to measure the performance of our code, and track how it changes over time

Using Google Benchmark

Integrating Clang-Tidy to enforce good practices and find bugs before we even compile

Using Clang-Tidy

Automated Analysis

Automating the entire development lifecycle using Git for souce control, GitHub Actions for cloud builds, and CPack to create distributable packages and installers.

An introduction to Git, the version control system that underpins modern collaborative software development and automated build pipelines.

Source Control with Git

Learn how to automate your build and test process with Continuous Integration (CI) and a build server. This lesson provides a guide to creating a GitHub Actions workflow for a CMake project.

Build Servers and Continuous Integration

Learn to package your C++ projects using CMake's CPack. This lesson covers creating developer ZIP archives and professional Windows MSI installers with components.

Packaging with CPack

Learn to automate the packaging process by integrating CPack with a multi-platform GitHub Actions workflow

Packaging with GitHub Actions

Learn to automate the creation of a professional Windows installer by integrating CPack, the WiX Toolset, and a multi-platform GitHub Actions workflow.

Creating Installers with CPack and GitHub Actions

Learn to automate the release process using a GitHub Actions workflow that builds, packages, and publishes artifacts to a GitHub Release

Deployment with GitHub Releases

Continuous Integration and Packaging

If you have a basic grasp of C++ but find the build process intimidating, this course is for you. We assume you know the language, but not how to manage large projects.

Manage complex, cross-platform builds using industry-standard tools. Create scalable build systems that automate the entire development lifecycle.

This course is a comprehensive deep-dive into the entire C++ build ecosystem, centered around the power and flexibility of modern CMake. We leave no stone unturned.

Start with a foundational understanding of compilers, linkers, static vs. shared libraries, and object files.

The Full Build Pipeline

Learn every aspect of the CMake language, from variables and control flow to functions, modules, and generator expressions.

Complete CMake Language Mastery

Master the modern target-centric paradigm, including properties, usage requirements, and abstract targets.

Advanced Target Management

Explore every method for handling dependencies, from `find_package` and `FetchContent` to vcpkg and Conan, including versioning and cross-compilation.

In-Depth Dependency Management

Integrate a full suite of professional tools for testing (CTest, GoogleTest), analysis (ASan, Clang-Tidy), and packaging (CPack).

Total Workflow Automation

Build a fully automated deployment pipeline that takes your code from a Git push to a published GitHub Release with multi-platform installers.

End-to-End CI/CD and Deployment

What You'll Learn

Become a software engineer with C++.  Starting from the basics, we guide you step by step along the way

Intro to C++ Programming

If you're completely new to programming or want a thorough introduction, consider starting with our free introductory course:

New to Programming?

Managing C++ Projects Using CMake

In the last lesson, we learned how `add_custom_command()` can inject external scripts into our build process. We saw that it's perfect for tasks that are an integral part of building a specific target, like copying a binary after it's built.


However, not every task is directly related to compiling code. Developers often need to perform utility actions that aren't part of the standard build.  Common examples include:

- Running a code formatter like `clang-format` across the entire codebase.  We'll walk through this as a practical example of these techniques in the next lessons.
- Generating documentation with a tool like Doxygen, which we cover later in the chapter.
- Running a static analysis tool to check for code quality issues.
- Any recurring task in our workflow, like copying all the files in one directory to another.

These actions don't produce a library or an executable, but they are still valuable parts of the development workflow. This is where **custom targets** come in. This lesson will teach you how to use `add_custom_target()` to create these standalone, command-driven targets.


## Phony Targets


If you've ever used a `Makefile`, you're likely familiar with targets like `make clean` or `make install`. These are called **phony targets** because they don't correspond to an actual file named `clean` or `install`. They are simply named shortcuts for a sequence of commands.


The `add_custom_target()` command in CMake creates the equivalent of a phony target. It defines a new target that you can "build" by name, but unlike an executable or library, it's not expected to produce an output file. Its only purpose is to execute one or more commands.


The key distinction is:

- `add_custom_command()` attaches a command to an **existing** target or file. It's part of the process of building something else.
- `add_custom_target()` creates a **new**, standalone target.

## Creating a Utility with `add_custom_target()`


The syntax for creating a custom target is straightforward:

- We provide a name for our target - `say_hello` in the following example
- An optional `COMMENT`, which can describe what our target is for and may be displayed in the terminal when we "build" our target
- We provide one or more commands to run using the `COMMAND` keyword

Here's a basic target that just logs some messages to the terminal:


<CodeFile path="CMakeLists.txt">


```c++
#<cmake>
cmake_minimum_required(VERSION 3.16)
project(Greeter)

add_subdirectory(app)

add_custom_target(say_hello#<h>
  COMMENT "Saying hello to the developer..."#<h>
  COMMAND ${CMAKE_COMMAND} -E echo "Hello there!"#<h>
  COMMAND ${CMAKE_COMMAND} -E echo "This is a second command"#<h>
)#<h>
```


</CodeFile>


By default, a custom target is **not** part of the normal build. You have to explicitly ask to build it. This makes it perfect for optional developer utilities.


### Building a Custom Target


After configuring our project, we can run our new target using the `--target` flag as part of the build step:


```c++
//<ti>
cmake --build . --target say_hello
```


This command tells the build system, "Ignore the default build process and just build the target named `say_hello`."  In this example, you may see the comment we provided, in addition to the execution of our two `echo` commands:


```c++
//<o>
[1/1] Saying hello to the developer...
Hello there!
This is a second command
```


The idea here is that we provide a simple, memorable command (`--target say_hello`) for a common developer task that might otherwise require more effort to complete.  We'll show some practical examples of this throughout the rest of the chapter


### CMake-Provided Targets


By default, CMake also provides some utility targets for us.  For example, the `clean` target deletes our compiled outputs, thereby forcing them to be recompiled from scratch on the next build:


```c++
//<ti>
cmake --build . --target clean
```


```c++
//<o>
[1/1] Cleaning all built files...
Cleaning... 4 files.
```


The `help` target lists all of the available targets, both the targets that CMake provides by default, as well as any targets we have added to our `CMakeLists.txt` files:


```c++
//<ti>
cmake --build . --target help
```


<Pw>


## The `ALL` Keyword


What if you want a custom target to run as part of the default build? You can achieve this by adding the `ALL` keyword to its definition.


<CodeFile path="CMakeLists.txt">


```c++
#<cmake>
cmake_minimum_required(VERSION 3.16)
project(Greeter)

add_subdirectory(app)

add_custom_target(print_message ALL#<h>
  COMMENT "Printing a message..."#<h>
  COMMAND ${CMAKE_COMMAND} -E echo#<h>
    "This message also prints on the default build"#<h>
)#<h>

add_custom_target(say_hello
  COMMENT "Saying hello to the developer..."
  COMMAND ${CMAKE_COMMAND} -E echo "Hello there!"
  COMMAND ${CMAKE_COMMAND} -E echo "This is a second command"
)
```


</CodeFile>


We can still run this target by itself in the usual way:


```c++
//<ti>
cmake --build . --target print_message
```


```c++
//<o>
[1/1] Printing a message...
This message also prints on the default build
```


But it will also run as part of the default build:


```c++
//<ti>
cmake --build .
```


```c++
//<o>
...
[3/5] Printing a message...
This message also prints on default builds
....
```


In this example, our target was built as step 3 in a 5-part build, but we'll learn how to control this later in the lesson.


## Building Custom Targets with a Preset


Within a build preset, we can specify which targets we want to be built using a `targets` array.  Creating a preset to build both of our new targets would look like this:


<CodeFile path="CMakePresets.json">


```c++
{
  "version": 3,
  "configurePresets": [{
    "name": "base",
    "binaryDir": "${sourceDir}/build"
  }],
  "buildPresets": [{
    "name": "print_stuff",
    "configurePreset": "base",
    "targets": ["say_hello", "print_message"]
  }]
}
```


</CodeFile>


We can use this preset as part of the build step in the usual way.  Remember, when using a preset, we should run the command from the root of our project, where our `CMakePresets.json` file is.


The configure step looks like this:


```c++
//<ti>
cmake --preset base
```


Followed by the build step:


```c++
//<ti>
cmake --build --preset print_stuff
```


```c++
//<o>
[1/2] Printing a message...
This message also prints on the default build
[2/2] Saying hello to the developer...
Hello there!
This is a second command
```


## Declaring Dependencies with `add_dependencies()`


A custom target is a node in CMake's dependency graph just like any other target. As we've seen, commands like `target_link_libraries()` can automatically create these links as a side effect.


However, for custom targets that don't need to be "linked" in the C++ sense, we can directly set up their dependencies using the `add_dependencies()` command.


In the following contrived example, we state that `print_message` depends on `say_hello`:


<CodeFile path="CMakeLists.txt">


```c++
#<cmake>
cmake_minimum_required(VERSION 3.16)
project(Greeter)

add_subdirectory(app)

add_custom_target(print_message ALL
  COMMENT "Printing a message..."
  COMMAND ${CMAKE_COMMAND} -E echo
    "This message also prints on the default build"
)

add_custom_target(say_hello
  COMMENT "Saying hello to the developer..."
  COMMAND ${CMAKE_COMMAND} -E echo "Hello there!"
  COMMAND ${CMAKE_COMMAND} -E echo "This is a second command"
)

add_dependencies(print_message say_hello)#<h>
```


</CodeFile>


Now, when we run our build, CMake will respect this dependency.  It ensures `say_hello` is built **before** `print_message`:


```c++
//<ti>
cmake --build --preset=print_stuff
```


```c++
//<o>
[1/2] Saying hello to the developer...
Hello there!
This is a second command
[2/2] Printing a message...
This message also prints on the default build
```


### The `DEPENDS` Argument


When our target is being created by `add_custom_target()`, we don't need to use `add_dependencies()`.  Instead, we provide the dependencies as arguments to `add_custom_target()` if we prefer.  We do this using the `DEPENDS` keyword, followed by one or more target names:


```c++
#<cmake>
add_custom_target(print_message ALL
  COMMENT "Printing a message..."
  DEPENDS say_hello#<h>
  COMMAND ${CMAKE_COMMAND} -E echo
    "This message also prints on the default build"
)
```


## Executing Targets


The tools we use as `COMMAND` arguments within `add_custom_target()` and `add_custom_command()` can be targets within our build.


To set this up, we simply provide the name of the target.  In the following example, we add a `run` target that executes the `GreeterApp` application that CMake is already managing:


<CodeFile path="CMakeLists.txt">


```c++
#<cmake>
cmake_minimum_required(VERSION 3.16)
project(Greeter)

add_subdirectory(app)

add_custom_target(run
  COMMENT "Running GreeterApp..."
  COMMAND GreeterApp
)
```


</CodeFile>


Behind the scenes, CMake is smart enough to understand that this means `run` depends on `GreeterApp`.  As such, we don't need an `add_dependencies()` call or `DEPENDS` argument, although we could still add them if we prefer.


Either way, if we try to build this `run` target whilst `GreeterApp` hasn't been built or isn't up to date, CMake will first build it.  From our build directory, we can test this using:


```c++
//<ti>
cmake --build . --target run
```


```c++
//<o>
[1/2] Linking CXX executable app\GreeterApp.exe
[2/2] Running GreeterApp...
Hello World
```


## Summary


Custom targets are the way to integrate any non-compilation task into your build workflow. They provide named entry points for developers to perform common utility actions.

- **Phony Targets**: `add_custom_target()` creates a target that runs commands but doesn't produce a file. It's the CMake equivalent of a phony target in a `Makefile`.
- **Explicit Invocation**: Custom targets are not built by default. A user must build them explicitly with `cmake --build . --target <name>`, making them ideal for optional utilities like `format` or `docs`.
- **The** **`ALL`** **Keyword**: Adding `ALL` to a custom target's definition makes it part of the default build, ensuring its commands run every time.
- **Using Build Presets**: A build preset can specify which target(s) it builds using a `targets` array.
- **Explicit Dependencies**: Use `add_dependencies()` to create a dependency between a normal target and a custom target, ensuring the custom target's commands run before the normal target is built.

<Preview>


### Practical Example: ClangFormat


In the next lesson, we'll walk through one of the most common uses for custom targets - **code formatting**.


We'll install **ClangFormat**, learn how to configure it for our project, and learn how to run it when we want to fix layout problems in our code files.


Finally, we'll encapsulate this complex workflow into a custom CMake target, letting us quickly execute it any time we need.


</Preview>


</Pw>

Custom Actions as Build Steps

`add_custom_target()` Documentation

`add_dependencies()` Documentation

Phony Targets

`add_custom_command()` vs `add_custom_target()`

CMake, custom targets, and commands

Master add_custom_target() in CMake to create standalone utility targets. This guide explains phony targets, dependencies with add_dependencies(), and provides real-world examples for code formatting and documentation generation.

CMake Custom Targets: Automating Developer Utilities

Creating a Utility with `add_custom_target()`

Declaring Dependencies with `add_dependencies()`

Custom Targets and Build Utilities

Understanding the Basics

Practical Applications

Common Mistakes

Next Steps

Additional Resources

Assessment Preparation

Managing C++ Projects Using CMake