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CPM.cmake is a cross-platform CMake script that adds dependency management capabilities to CMake.It's built as a thin wrapper around CMake'sFetchContent module that adds version control, caching, a simple APIand more.

Any downloadable project or resource can be added as a version-controlled dependency through CPM, it is not necessary to modify or package anything.Projects using modern CMake are automatically configured and their targets can be used immediately.For everything else, the targets can be created manually after the dependency has been downloaded (see thesnippets below for examples).

• CPM: An Awesome Dependency Manager for C++ with CMake
• CMake and the Future of C++ Package Management

cmake_minimum_required(VERSION 3.14 FATAL_ERROR)# create projectproject(MyProject)# add executableadd_executable(main main.cpp)# add dependenciesinclude(cmake/CPM.cmake)CPMAddPackage("gh:fmtlib/fmt#7.1.3")CPMAddPackage("gh:nlohmann/json@3.10.5")CPMAddPackage("gh:catchorg/Catch2@3.4.0")# link dependenciestarget_link_libraries(main fmt::fmt nlohmann_json::nlohmann_json Catch2::Catch2WithMain)

See theexamples directory for complete examples with source code and checkbelow or in thewiki for example snippets.

To add CPM to your current project, simply add thelatest release ofCPM.cmake orget_cpm.cmake to your project'scmake directory.The command below will perform this automatically.

mkdir -p cmakewget -O cmake/CPM.cmake https://github.com/cpm-cmake/CPM.cmake/releases/latest/download/get_cpm.cmake

You can also download CPM.cmake directly from your project'sCMakeLists.txt. See thewiki for more details.

AfterCPM.cmake has beenadded to your project, the functionCPMAddPackage can be used to fetch and configure a dependency.Afterwards, any targets defined in the dependency can be used directly.CPMAddPackage takes the following named parameters.

CPMAddPackage(NAME# The unique name of the dependency (should be the exported target's name)VERSION# The minimum version of the dependency (optional, defaults to 0)  PATCHES# Patch files to be applied sequentially using patch and PATCH_OPTIONS (optional)OPTIONS# Configuration options passed to the dependency (optional)  DOWNLOAD_ONLY# If set, the project is downloaded, but not configured (optional)  [...]# Origin parameters forwarded to FetchContent_Declare, see below)

The origin may be specified by aGIT_REPOSITORY, but other sources, such as direct URLs, arealso supported.IfGIT_TAG hasn't been explicitly specified it defaults tov(VERSION), a common convention for git projects.On the other hand, ifVERSION hasn't been explicitly specified, CPM can automatically identify the version from the git tag in some common cases.GIT_TAG can also be set to a specific commit or a branch name such asmaster, however this isn't recommended, as such packages will only be updated when the cache is cleared.

PATCHES takes a list of patch files to apply sequentially. For a basic example, seeHighway.We recommend that if you usePATCHES, you also setCPM_SOURCE_CACHE. Seeissue 577.

If an additional optional parameterEXCLUDE_FROM_ALL is set to a truthy value, then any targets defined inside the dependency won't be built by default. See theCMake docs for details.

If an additional optional parameterSYSTEM is set to a truthy value, the SYSTEM directory property of the subdirectory added will be set to true.See theadd_subdirectoryandSYSTEM target property for details.

A single-argument compact syntax is also supported:

# A git package from a given uri with a versionCPMAddPackage("uri@version")# A git package from a given uri with a git tag or commit hashCPMAddPackage("uri#tag")# A git package with both version and tag providedCPMAddPackage("uri@version#tag")

In the shorthand syntax if the URI is of the formgh:user/name, it is interpreted as GitHub URI and converted tohttps://github.com/user/name.git. If the URI is of the formgl:user/name, it is interpreted as aGitLab URI and converted tohttps://gitlab.com/user/name.git. If the URI is of the formbb:user/name, it is interpreted as aBitbucket URI and converted tohttps://bitbucket.org/user/name.git. Otherwise the URI used verbatim as a git URL. All packages added using the shorthand syntax will be added using theEXCLUDE_FROM_ALL andSYSTEM flag.

The single-argument syntax also works for URLs:

# An archive package from a given url. The version is inferredCPMAddPackage("https://example.com/my-package-1.2.3.zip")# An archive package from a given url with an MD5 hash providedCPMAddPackage("https://example.com/my-package-1.2.3.zip#MD5=68e20f674a48be38d60e129f600faf7d")# An archive package from a given url. The version is explicitly givenCPMAddPackage("https://example.com/my-package.zip@1.2.3")

After callingCPMAddPackage, the following variables are defined in the local scope, where<dependency> is the name of the dependency.

• <dependency>_SOURCE_DIR is the path to the source of the dependency.
• <dependency>_BINARY_DIR is the path to the build directory of the dependency.
• <dependency>_ADDED is set toYES if the dependency has not been added before, otherwise it is set toNO.
• CPM_LAST_PACKAGE_NAME is set to the determined name of the last added dependency (equivalent to<dependency>).

For using CPM.cmake projects with external package managers, such as conan or vcpkg, setting the variableCPM_USE_LOCAL_PACKAGES will make CPM.cmake try to add a package throughfind_package first, and add it from source if it doesn't succeed.

In rare cases, this behaviour may be desirable by default. The functionCPMFindPackage will try to find a local dependency via CMake'sfind_package and fallback toCPMAddPackage, if the dependency is not found.

To update CPM to the newest version, update the script in the project's root directory, for example by running the same command as foradding CPM.Dependencies using CPM will automatically use the updated script of the outermost project.

• Small and reusable projects CPM takes care of all project dependencies, allowing developers to focus on creating small, well-tested libraries.
• Cross-Platform CPM adds projects directly at the configure stage and is compatible with all CMake toolchains and generators.
• Reproducible builds By versioning dependencies via git commits or tags it is ensured that a project will always be buildable.
• Recursive dependencies Ensures that no dependency is added twice and all are added in the minimum required version.
• Plug-and-play No need to install anything. Just add the script to your project and you're good to go.
• No packaging required Simply add all external sources as a dependency.
• Simple source distribution CPM makes including projects with source files and dependencies easy, reducing the need for monolithic header files or git submodules.

• No pre-built binaries For every new build directory, all dependencies are initially downloaded and built from scratch. To avoid extra downloads it is recommend to set theCPM_SOURCE_CACHE environmental variable. Using a caching compiler such asccache can drastically reduce build time.
• Dependent on good CMakeLists Many libraries do not have CMakeLists that work well for subprojects. Luckily this is slowly changing, however, until then, some manual configuration may be required (see the snippetsbelow for examples). For best practices on preparing projects for CPM, see thewiki.
• First version used In diamond-shaped dependency graphs (e.g.A depends onC@1.1 andB, which itself depends onC@1.2 the first added dependency will be used (in this caseC@1.1). In this case, B requires a newer version ofC thanA, so CPM will emit a warning. This can be easily resolved by adding a new version of the dependency in the outermost project, or by introducing apackage lock file.
• Some CMake policies set toNEW Including CPM.cmake will lead to several CMake policies being set toNEW. Users which need the old behavior will need to manually modify their CMake code to ensure they're set toOLD at the appropriate places. The policies are:
  • CMP0077 andCMP0126. They make setting package options fromCMPAddPackage possible.
  • CMP0135 It allows for proper package rebuilds of packages which are archives, source cache is not used, and the package URL is changed to an older version.
  • CMP0150 Relative paths provided toGIT_REPOSITORY are treated as relative to the parent project's remote.

For projects with more complex needs and where an extra setup step doesn't matter, it may be worth to check out an external C++ package manager such asvcpkg,conan orhunter.Dependencies added withCPMFindPackage should work with external package managers.Additionally, the optionCPM_USE_LOCAL_PACKAGES will enablefind_package for all CPM dependencies.

The usual way to add libraries in CMake projects is to callfind_package(<PackageName>) and to link against libraries defined in a<PackageName>_LIBRARIES variable.While simple, this may lead to unpredictable builds, as it requires the library to be installed on the system and it is unclear which version of the library has been added.Additionally, it is difficult to cross-compile projects (e.g. for mobile), as the dependencies will need to be rebuilt manually for each targeted architecture.

CPM.cmake allows dependencies to be unambiguously defined and builds them from source.Note that the behaviour differs fromfind_package, as variables exported to the parent scope (such as<PackageName>_LIBRARIES) will not be visible after adding a package using CPM.cmake.The behaviour can beachieved manually, if required.

CPM.cmake is a wrapper for CMake's FetchContent module and adds a number of features that turn it into a useful dependency manager.The most notable features are:

• A simpler to use API
• Version checking: CPM.cmake will check the version number of any added dependency and emit a warning if another dependency requires a more recent version.
• Offline builds: CPM.cmake will override CMake's download and update commands, which allows new builds to be configured while offline if all dependenciesare available locally.
• Automatic shallow clone: if a version tag (e.g.v2.2.0) is provided andCPM_SOURCE_CACHE is used, CPM.cmake will perform a shallow clone of the dependency, which should be significantly faster while using less storage than a full clone.
• Overridable: allCPMAddPackage can be configured to usefind_package by setting aCMake flag, making it easy to integrate into projects that may require local versioning through the system's package manager.
• Package lock files for easier transitive dependency management.
• Dependencies can be overriddenper-build using CMake CLI parameters.

ExternalProject works similarly as FetchContent, however waits with adding dependencies until build time.This has a quite a few disadvantages, especially as it makes using custom toolchains / cross-compiling very difficult and can lead to problems with nested dependencies.

To avoid re-downloading dependencies, CPM has an optionCPM_SOURCE_CACHE that can be passed to CMake as-DCPM_SOURCE_CACHE=<path to an external download directory>.This will also allow projects to be configured offline, as long as the dependencies have been added to the cache before.It may also be defined system-wide as an environmental variable, e.g. by exportingCPM_SOURCE_CACHE in your.bashrc or.bash_profile.

export CPM_SOURCE_CACHE=$HOME/.cache/CPM

Note that passing the variable as a configure option to CMake will always override the value set by the environmental variable.

You can useCPM_SOURCE_CACHE on GitHub Actions workflowscache and combine it with ccache, to make your CI faster. See thewiki for more info.

The directory where the version for a project is stored is by default the hash of the arguments toCPMAddPackage().If for instance the patch command uses external files, the directory name can be set with the argumentCUSTOM_CACHE_KEY.

If set, CPM will forward all calls toCPMFindPackage asCPMAddPackage.This is useful to create reproducible builds or to determine if the source parameters have all been set correctly.This can also be set as an environmental variable.This can be controlled on a per package basis with theCPM_DOWNLOAD_<dependency name> variable.

CPM can be configured to usefind_package to search for locally installed dependencies first by setting the CMake optionCPM_USE_LOCAL_PACKAGES.

If the optionCPM_LOCAL_PACKAGES_ONLY is set, CPM will emit an error if the dependency is not found locally.These options can also be set as environmental variables.

In the case thatfind_package requires additional arguments, the parameterFIND_PACKAGE_ARGUMENTS may be specified in theCPMAddPackage call. The value of this parameter will be forwarded tofind_package.

Note that this does not apply to dependencies that have been defined with a truthyFORCE parameter. These will be added as defined.

By default, CPM will override anyfind_package commands to use the CPM downloaded version.This is equivalent to theOVERRIDE_FIND_PACKAGE FetchContent option, which has no effect in CPM.To disable this behaviour set theCPM_DONT_UPDATE_MODULE_PATH option.This will not work forfind_package(CONFIG) in CMake versions before 3.24.

If set, CPM use additional directory level in cache to improve readability of packages names in IDEs like CLion. It changes cache structure, so all dependencies are downloaded again. There is no problem to mix both structures in one cache directory but then there may be 2 copies of some dependencies.This can also be set as an environmental variable.

Library developers are often in the situation where they work on a locally checked out dependency at the same time as on a consumer project.It is possible to override the consumer's dependency with the version by supplying the CMake optionCPM_<dependency name>_SOURCE set to the absolute path of the local library.For example, to use the local version of the dependencyDep at the path/path/to/dep, the consumer can be built with the following command.

cmake -Bbuild -DCPM_Dep_SOURCE=/path/to/dep

In large projects with many transitive dependencies, it can be useful to introduce a package lock file.This will list all CPM.cmake dependencies and can be used to update dependencies without modifying the originalCMakeLists.txt.To use a package lock, add the following line directly after including CPM.cmake.

CPMUsePackageLock(package-lock.cmake)

To create or update the package lock file, build thecpm-update-package-lock target.

cmake -Bbuildcmake --build build --target cpm-update-package-lock

See thewiki for more info.

When using CPM.cmake with private repositories, there may be a need to provide anaccess token to be able to clone other projects. Instead of providing the token in CMake, we recommend to provide the regular URL and usegit-config to rewrite the URLs to include the token.

As an example, you could include one of the following in your CI script.

# Githubgit config --global url."https://${USERNAME}:${TOKEN}@github.com".insteadOf"https://github.com"

# GitLabgit config --global url."https://gitlab-ci-token:${CI_JOB_TOKEN}@gitlab.com".insteadOf"https://gitlab.com"

Some amazing projects that are built using the CPM.cmake package manager.If you know others, feel free to add them here through a PR.

These examples demonstrate how to include some well-known projects with CPM.See thewiki for more snippets.

CPMAddPackage("gh:catchorg/Catch2@2.5.0")

CPMAddPackage("gh:ericniebler/range-v3#0.12.0")

# as the tag is in an unusual format, we need to explicitly specify the versionCPMAddPackage("gh:jbeder/yaml-cpp#yaml-cpp-0.6.3@0.6.3")

CPMAddPackage(NAME nlohmann_jsonVERSION 3.9.1  GITHUB_REPOSITORY nlohmann/jsonOPTIONS"JSON_BuildTests OFF")

Boost is a large project and will take a while to download. UsingCPM_SOURCE_CACHE is strongly recommended. Cloning moves much moredata than a source archive, so this sample will use a compressedsource archive (tar.xz) release from Boost's github page.

# boost is a huge project and directly downloading the 'alternate release'# from github is much faster than recursively cloning the repo.CPMAddPackage(NAME BoostVERSION 1.84.0  URL https://github.com/boostorg/boost/releases/download/boost-1.84.0/boost-1.84.0.tar.xz  URL_HASH SHA256=2e64e5d79a738d0fa6fb546c6e5c2bd28f88d268a2a080546f74e5ff98f29d0eOPTIONS"BOOST_ENABLE_CMAKE ON")

For a working example of using CPM to download and configure the Boost C++ Libraries seehere.

# the install option has to be explicitly set to allow installationCPMAddPackage(  GITHUB_REPOSITORY jarro2783/cxxoptsVERSION 2.2.1OPTIONS"CXXOPTS_BUILD_EXAMPLES NO""CXXOPTS_BUILD_TESTS NO""CXXOPTS_ENABLE_INSTALL YES")

CPMAddPackage(NAME benchmark  GITHUB_REPOSITORY google/benchmarkVERSION 1.5.2OPTIONS"BENCHMARK_ENABLE_TESTING Off")if(benchmark_ADDED)# enable c++11 to avoid compilation errors  set_target_properties(benchmark PROPERTIES CXX_STANDARD 11)endif()

CPMAddPackage(NAME lua  GIT_REPOSITORY https://github.com/lua/lua.gitVERSION 5.3.5  DOWNLOAD_ONLYYES)if (lua_ADDED)# lua has no CMake support, so we create our own target  FILE(GLOB lua_sources${lua_SOURCE_DIR}/*.c)  list(REMOVE_ITEM lua_sources"${lua_SOURCE_DIR}/lua.c""${lua_SOURCE_DIR}/luac.c")  add_library(luaSTATIC${lua_sources})  target_include_directories(luaPUBLIC      $<BUILD_INTERFACE:${lua_SOURCE_DIR}>  )endif()

For a full example on using CPM to download and configure lua with sol2 seehere.

See theexamples directory for full examples with source code and check out thewiki for many more example snippets.

Using a compressed source archive is usually much faster than a shallowclone. Optionally, you can verify the integrity usingSHA256 or similar. Setting the hash is useful to ensure aspecific source is imported, especially since tags, branches, andarchives can change.

Let's look at addingspdlog to a project:

CPMAddPackage(NAME     spdlog  URL      https://github.com/gabime/spdlog/archive/refs/tags/v1.12.0.zip  URL_HASH SHA256=6174bf8885287422a6c6a0312eb8a30e8d22bcfcee7c48a6d02d1835d7769232)

URL_HASH is optional, but it's a good idea for releases.

Information for determining the URL is foundhere.

Not every software package provides releases, but for those that do,they can be found on the release page of the project. In a browser,the URL of the specific release is determined in a browser isdetermined by right clicking and selectingCopy link address (orsimilar) for the desired release. This is the value you will use inthe URL section.

This is the URL for spdlog release 1.13.0 in zip format:https://github.com/gabime/spdlog/archive/refs/tags/v1.13.0.zip

The URL for branches is non-obvious from a browser. But it's still fairly easy to figure it out. The format is as follows:

https://github.com/<user>/<name>/archive/refs/heads/<branch-name>.<archive-type>

Archive type can be one oftar.gz orzip.

The URL for branchv2.x of spdlog is:https://github.com/gabime/spdlog/archive/refs/heads/v2.x.tar.gz

Tags are similar, but with this format:

https://github.com/<user>/<name>/archive/refs/tags/<tag-name>.<archive-type>

Tagv1.8.5 of spdlog is this:

https://github.com/gabime/spdlog/archive/refs/tags/v1.8.5.tar.gz

Exactly like the release.

If a specific commit contains the code you need, it's defined as follows:

https://github.com/<user>/<name>/archive/<commit-hash>.<archive-type>

Example:https://github.com/gabime/spdlog/archive/c1569a3d293a6b511ecb9c18b2298826c9578d9f.tar.gz

The following snippet illustrates determining the SHA256 hash on a linux machine usingwget andsha256sum:

wget https://github.com/gabime/spdlog/archive/refs/tags/v1.13.0.zip -O -| sha256sum