Table Of ContentModern CMake
for C++
Discover a better approach to building, testing,
and packaging your software
Rafał Świdziński
BIRMINGHAM—MUMBAI
Modern CMake for C++
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To my family: my parents, Bożena and Bogdan, my sisters, Ewelina and
Justyna, and my wife, Katarzyna, for their ongoing support and advice.
– Rafał Świdziński
Contributors
About the author
Rafał Świdziński works as a staff engineer at Google. With over 10 years of professional
experience as a full stack developer, he has been able to experiment with a vast multitude
of programming languages and technologies. During this time, he has been building
software under his own company and for corporations including Cisco Meraki, Amazon,
and Ericsson.
Originally from Łódź, Poland, he now lives in London, UK, from where he runs
a YouTube channel, "Smok," discussing topics related to software development. He tackles
technical problems, including real-life and work-related challenges encountered by many
people in the field. Throughout his work, he explains the technical concepts in detail and
demystifies the art and science behind the role of software engineer. His primary focus is
on high-quality code and the craftsmanship of programming.
About the reviewers
Sergio Guidi Tabosa Pessoa is a software engineer with more than 30 years of experience
in software development and maintenance, from complex enterprise software projects to
modern mobile applications. In the early days, he worked primarily with the Microsoft
stack, but soon discovered the power of the UNIX and Linux operating systems. Even
though he has worked with many languages over the years, C and C++ remain his favorite
languages for their power and speed.
He has a bachelor's degree in computer science and an MBA in IT management and is
always hungry to learn new technologies, break code, and learn from his mistakes. He
currently lives in Brazil with his wife, two Yorkshire Terriers, and two cockatiels.
First and foremost, I would like to thank all the people involved in this
project, including the author for crafting such a great piece of work, and
Packt Publishing for giving me this opportunity. I also would like to thank
my beautiful wife, Lucia, as well as Touché and Lion, for their patience and
for allowing me the time needed to help with this book.
Holding an engineering degree from ENSEEIHT and a Ph.D. in computer science from
UVSQ in France, Eric Noulard has been writing and compiling source code in a variety of
languages for 20 years. A user of CMake since 2006, he has also been an active contributor
to the project for several years. During his career, Eric has worked for private companies
and government agencies. He is now employed by Antidot, a software vendor responsible
for developing and marketing high-end information retrieval technology and solutions.
Mohammed Alqumairi is a software engineer at Cisco Meraki with experience in
developing critical and performant backend services using a variety of languages and
frameworks, with a particular focus on modern C++, CMake, and the Poco libraries.
Mohammed graduated with honors from City, University of London, with a B.Sc. in
Computer Science.
Table of Contents
Preface
Section 1: Introducing CMake
1
First Steps with CMake
Technical requirements 4 The source tree 30
Understanding the basics 5 The build tree 30
Listfiles 31
What is CMake? 5
CMakeLists.txt 32
How does it work? 7
CMakeCache.txt 33
Installing CMake on different The Config-files for packages 34
platforms 10 The cmake_install.cmake,
Docker 11 CTestTestfile.cmake, and CPackConfig.
cmake files 35
Windows 12
CMakePresets.json and
Linux 13
CMakeUserPresets.json 35
macOS 13
Ignoring files in Git 39
Building from the source 14
Discovering scripts and modules 40
Mastering the command line 14
Scripts 40
CMake 15
Utility modules 41
CTest 26
Find-modules 41
CPack 27
The CMake GUI 28 Summary 42
CCMake 29
Further reading 42
Navigating the project files 30
viii Table of Contents
2
The CMake Language
Technical requirements 44 Understanding control
The basics of the CMake structures in CMake 63
Language syntax 45 Conditional blocks 63
Comments 45 Loops 68
Command invocations 47 Command definitions 70
Command arguments 49
Useful commands 76
Working with variables 53 The message() command 76
Variable references 54 The include() command 78
Using the environment variables 55 The include_guard() command 79
Using the cache variables 57 The file() command 79
How to correctly use the variable The execute_process() command 79
scope in CMake 59
Summary 80
Using lists 61 Further reading 81
3
Setting Up Your First CMake Project
Technical requirements 84 Cross-compilation – what are host and
target systems? 100
Basic directives and commands 85
Abbreviated variables 100
Specifying the minimum CMake
Host system information 101
version – cmake_minimum_required() 85
Does the platform have 32-bit or 64-bit
Defining languages and metadata –
architecture? 102
project() 86
What is the endianness of the system? 103
Partitioning your project 87
Configuring the toolchain 103
Scoped subdirectories 90
Setting the C++ standard 103
Nested projects 92
Insisting on standard support 104
External projects 92
Vendor-specific extensions 105
Thinking about the project Interprocedural optimization 105
structure 93 Checking for supported compiler
Scoping the environment 99 features 106
Compiling a test file 106
Discovering the operating system 99
Table of Contents ix
Disabling in-source builds 108 Further reading 111
Summary 110
Section 2: Building With CMake
4
Working with Targets
Technical requirements 116 Using a custom command as a
generator 132
The concept of a target 116
Using a custom command as a target
Dependency graph 118
hook 134
Visualizing dependencies 121
Target properties 122 Understanding generator
What are transitive usage expressions 135
requirements? 123 General syntax 136
Dealing with conflicting propagated Types of evaluation 137
properties 126
Examples to try out 144
Meet the pseudo targets 128
Build targets 130 Summary 148
Further reading 148
Writing custom commands 131
5
Compiling C++ Sources with CMake
Technical requirements 152 General level 165
The basics of compilation 152 Function inlining 167
Loop unrolling 168
How compilation works 153
Loop vectorization 170
Initial configuration 155
Managing sources for targets 156 Managing the process of
compilation 171
Preprocessor configuration 158
Reducing compilation time 171
Providing paths to included files 158
Finding mistakes 176
Preprocessor definitions 159
Configuring the headers 162 Summary 182
Configuring the optimizer 164 Further reading 183
