Modern C++
Programming
16. C++ Ecosystem
Cmake and Other Tools
Federico Busato
2024-11-05
CMake Overview
CMake is an open-source, cross-platform family of tools designed to build,
test and package software
CMake is used to control the software compilation process using simple platform and
compiler independent configuration files, and generate native Makefile/Ninja and
workspaces that can be used in the compiler environment of your choice
CMake features:
• Turing complete language (if/else, loops, functions, etc.)
• Multi-platform (Windows, Linux, etc.)
• Open-Source
• Generate: makefile, ninja, etc.
• Supported by many IDEs: Visual Studio, Clion, Eclipse, etc.
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CMake Books
Professional CMake: A Practical Guide
(14th)
C. Scott, 2023
Modern CMake for C++ (2nd)
R.
´
Swidzi
´
nski, 2024
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Install CMake
Using PPA repository
$ wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null |
gpg --dearmor - | sudo tee /etc/apt/trusted.gpg.d/kitware.gpg >/dev/null
$ sudo apt-add-repository 'deb https://apt.kitware.com/ubuntu/ focal main' # bionic, xenial
$ sudo apt update
$ sudo apt install cmake cmake-curses-gui
Using the installer or the pre-compiled binaries: cmake.org/download/
# download the last cmake package, e.g. cmake-x.y.z-linux-x86_64.sh
$ sudo sh cmake-x.y.z-linux-x86_64.sh
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A Minimal Example
CMakeLists.txt:
project(my_project) # project name
add_executable(program program.cpp) # compile command
# we are in the project root dir
$ mkdir build # 'build' dir is needed for isolating temporary files
$ cd build
$ cmake .. # search for CMakeLists.txt directory
$ make # makefile automatically generated
Scanning dependencies of target program
[100%] Building CXX object CMakeFiles/out_program.dir/program.cpp.o
Linking CXX executable program
[100%] Built target program
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Parameters and Message
CMakeLists.txt:
project(my_project)
add_executable(program program.cpp)
if (VAR)
message("VAR is set, NUM is ${NUM}")
else()
message(FATAL_ERROR "VAR is not set")
endif()
$ cmake ..
VAR is not set
$ cmake -DVAR=ON -DNUM=4 ..
VAR is set, NUM is 4
...
[100%] Built target program
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Language Properties
project(my_project
DESCRIPTION "Hello World"
HOMEPAGE_URL "github.com/"
LANGUAGES CXX)
cmake_minimum_required(VERSION 3.15)
set(CMAKE_CXX_STANDARD 14) # force C++14
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF) # no compiler extensions
add_executable(program ${PROJECT_SOURCE_DIR}/program.cpp) #$
# PROJECT_SOURCE_DIR is the root directory of the project
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Target Commands
add_executable(program) # also add_library(program)
target_include_directories(program
PUBLIC include/
PRIVATE src/)
# target_include_directories(program SYSTEM ...) for system headers
target_sources(program # best way for specifying
PRIVATE src/program1.cpp # program sources and headers
PRIVATE src/program2.cpp
PUBLIC include/header.hpp)
target_compile_definitions(program PRIVATE MY_MACRO=ABCEF)
target_compile_options(program PRIVATE -g)
target_link_libraries(program PRIVATE boost_lib)
target_link_options(program PRIVATE -s)
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Build Types
project(my_project) # project name
cmake_minimum_required(VERSION 3.15) # minimum version
add_executable(program program.cpp)
if (CMAKE_BUILD_TYPE STREQUAL "Debug") # "Debug" mode
# cmake already adds "-g -O0"
message("DEBUG mode")
if (CMAKE_COMPILER_IS_GNUCXX) # if compiler is gcc
target_compile_options(program "-g3")
endif()
elseif (CMAKE_BUILD_TYPE STREQUAL "Release") # "Release" mode
message("RELEASE mode") # cmake already adds "-O3 -DNDEBUG"
endif()
$ cmake -DCMAKE_BUILD_TYPE=Debug ..
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Custom Targets and File Managing
project(my_project)
add_executable(program)
add_custom_target(echo_target # makefile target name
COMMAND echo "Hello" # real command
COMMENT "Echo target")
# find all .cpp file in src/ directory
file(GLOB_RECURSE SRCS ${PROJECT_SOURCE_DIR}/src/*.cpp)
# compile all *.cpp file
target_sources(program PRIVATE ${SRCS}) # prefer the explicit file list instead
$ cmake ..
$ make echo_target
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Local and Cached Variables
Cached variables can be reused across multiple runs, while local variables are only
visible in a single run. Cached FORCE variables can be modified only after the
initialization
project(my_project)
set(VAR1 "var1") # local variable
set(VAR2 "var2" CACHE STRING "Description1") # cached variable
set(VAR3 "var3" CACHE STRING "Description2" FORCE) # cached variable
option(OPT "This is an option" ON) # boolean cached variable
# same of var2
message(STATUS "${VAR1}, ${VAR2}, ${VAR3}, ${OPT}")
$ cmake .. # var1, var2, var3, ON
$ cmake -DVAR1=a -DVAR2=b -DVAR3=c -DOPT=d .. # var1, b, var3, d
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Manage Cached Variables
$ ccmake . # or 'cmake-gui'
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Find Packages
project(my_project) # project name
cmake_minimum_required(VERSION 3.15) # minimum version
add_executable(program program.cpp)
find_package(Boost 1.36.0 REQUIRED) # compile only if Boost library
# is found
if (Boost_FOUND)
target_include_directories("${PROJECT_SOURCE_DIR}/include" PUBLIC ${Boost_INCLUDE_DIRS})
else()
message(FATAL_ERROR "Boost Lib not found")
endif()
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Compile Commands
Generate JSON compilation database (compile commands.json)
It contains the exact compiler calls for each file that are used by other tools
project(my_project)
cmake_minimum_required(VERSION 3.15)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON) # <--
add_executable(program program.cpp)
Change the C/C++ compiler:
CC=clang CXX=clang++ cmake ..
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ctest 1/2
CTest is a testing tool (integrated in CMake) that can be used to automate updating,
configuring, building, testing, performing memory checking, performing coverage
project(my_project)
cmake_minimum_required(VERSION 3.5)
add_executable(program program.cpp)
enable_testing()
add_test(NAME Test1 # check if "program" returns 0
WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/build
COMMAND ./program <args>) # command can be anything
add_test(NAME Test2 # check if "program" print "Correct"
WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/build
COMMAND ./program <args>)
set_tests_properties(Test2
PROPERTIES PASS_REGULAR_EXPRESSION "Correct")
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ctest 2/2
Basic usage (call ctest):
$ make test # run all tests
ctest usage:
$ ctest -R Python # run all tests that contains 'Python' string
$ ctest -E Iron # run all tests that not contain 'Iron' string
$ ctest -I 3,5 # run tests from 3 to 5
Each ctest command can be combined with other tools (e.g. valgrind)
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ctest with Different Compile Options
It is possible to combine a custom target with ctest to compile the same code with
different compile options
add_custom_target(program-compile
COMMAND mkdir -p test-release test-ubsan test-asan # create dirs
COMMAND cmake .. -B test-release # -B change working dir
COMMAND cmake .. -B test-ubsan -DUBSAN=ON
COMMAND cmake .. -B test-asan -DASAN=ON
COMMAND make -C test-release -j20 program # -C run make in a
COMMAND make -C test-ubsan -j20 program # different dir
COMMAND make -C test-asan -j20 program)
enable_testing()
add_test(NAME Program-Compile
COMMAND make program-compile)
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CMake Alternatives - xmake
xmake is a cross-platform build utility based on
Lua.
Compared with makefile/CMakeLists.txt, the configuration syntax is more concise
and intuitive. It is very friendly to novices and can quickly get started in a short time.
Let users focus more on actual project development
Comparison: xmake vs cmake
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doxygen 1/6
Doxygen is the de facto standard tool for generating documentation from annotated
C++ sources
Doxygen usage
• comment the code with /// or /** comment */
• generate doxygen base configuration file
$ doxygen -g
• modify the configuration file Doxyfile
• generate the documentation
$ doxygen <config_file>
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doxygen 2/6
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doxygen 3/6
Doxygen requires the following tags for generating the documentation:
• @file Document a file
• @brief Brief description for an entity
• @param Run-time parameter description
• @tparam Template parameter description
• @return Return value description
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doxygen - Features 4/6
• Automatic cross references between functions, variables, etc.
• Specific highlight. Code `<code>` , input/output parameters
@param[in] <param>
• Latex/MathJax $<code>$
• Markdown (Markdown Cheatsheet link), Italic text *<code>* , bold text
**<code>** , table, list, etc.
• Call/Hierarchy graph can be useful in large projects (requires graphviz)
HAVE DOT = YES
GRAPHICAL HIERARCHY = YES
CALL GRAPH = YES
CALLER GRAPH = YES
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doxygen - Example 5/6
/**
* @file
* @copyright MyProject
* license BSD3, Apache, MIT, etc.
* @author MySelf
* @version v3.14159265359
* @date March, 2018
*/
/// @brief Namespace brief description
namespace my_namespace {
/// @brief "Class brief description"
/// @tparam R "Class template for"
template<typename R>
class A {
/**
* @brief "What the function does?"
* @details "Some additional details",
* Latex/MathJax: $\sqrt a$
* @tparam T Type of input and output
* @param[in] input Input array
* @param[out] output Output array
* @return `true` if correct,
* `false` otherwise
* @remark it is *useful* if ...
* @warning the behavior is **undefined** if
* @p input is `nullptr`
* @see related_function
*/
template<typename T>
bool my_function(const T* input, T* output);
/// @brief
void related_function();
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doxygen - Call Graph 6/6
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Doxygen Alternatives
M.CSS Doxygen C++ theme
Doxypress Doxygen fork
clang-doc LLVM tool
Sphinx Clear, Functional C++ Documentation with Sphinx + Breathe
+ Doxygen + CMake
standardese The nextgen Doxygen for C++ (experimental)
HDoc The modern documentation tool for C++ (alpha)
Adobe Hyde Utility to facilitate documenting C++
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Count Lines of Code - cloc
cloc counts blank lines, comment lines, and physical lines of source code in many
programming languages
$cloc my_project/
4076 text files.
3883 unique files.
1521 files ignored.
http://cloc.sourceforge.net v 1.50 T=12.0 s (209.2 files/s, 70472.1 lines/s)
-------------------------------------------------------------------------------
Language files blank comment code
-------------------------------------------------------------------------------
C 135 18718 22862 140483
C/C++ Header 147 7650 12093 44042
Bourne Shell 116 3402 5789 36882
Features: filter by-file/language, SQL database, archive support, line count diff, etc.
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Cyclomatic Complexity Analyzer - lyzard 1/3
Lizard is an extensible Cyclomatic Complexity Analyzer for many programming
languages including C/C++
Cyclomatic Complexity: is a software metric used to indicate the complexity of a program. It
is a quantitative measure of the number of linearly independent paths through a program
source code
$lizard my_project/
==============================================================
NLOC CCN token param function@line@file
--------------------------------------------------------------
10 2 29 2 start_new_player@26@./html_game.c
6 1 3 0 set_shutdown_flag@449@./httpd.c
24 3 61 1 server_main@454@./httpd.c
--------------------------------------------------------------
• CCN: cyclomatic complexity (should not exceed a threshold)
• NLOC: lines of code without comments
• token: Number of conditional statements
• param: Parameter count of functions
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Cyclomatic Complexity Analyzer - lyzard 2/3
CCN = 3
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Cyclomatic Complexity Analyzer - lyzard 3/3
CC Risk Evaluation
1-10 a simple program, without much risk
11-20 more complex, moderate risk
21-50 complex, high risk
> 50 untestable program, very high risk
CC Guidelines
1-5 The routine is probably fine
6-10 Start to think about ways to simplify the routine
> 10 Break part of the routine
Risk: Lizard: 15, OCLint: 10
• www.microsoftpressstore.com/store/code-complete-9780735619678
• blog.feabhas.com/2018/07/code-quality-cyclomatic-complexity
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Code Formatting - clang-format
clang-format is a tool to automatically format C/C++ code (and other languages)
$ clang-format <file/directory>
clang-format searches the configuration file .clang-format file located in the
closest parent directory of the input file
clang-format example:
IndentWidth: 4
UseTab: Never
BreakBeforeBraces: Linux
ColumnLimit: 80
SortIncludes: true
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AI-Powered Code Completion 1/2
AI-Powered Code Completion tools help writing code faster by drawing context
from comments and code to suggest individual lines and whole functions
Common features:
• Semantic completion
• Recognize common language patterns
• Use the documentation to infer this function name, return type, and arguments
• Suggest bug fixes
• Generate comments, documentation, and even Pull Request text
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