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https://github.com/cpm-cmake/CPM.cmake

📦 CMake's missing package manager. A small CMake script for setup-free, cross-platform, reproducible dependency management.
https://github.com/cpm-cmake/CPM.cmake

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📦 CMake's missing package manager. A small CMake script for setup-free, cross-platform, reproducible dependency management.

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README 

        






  







# Setup-free CMake dependency management



CPM.cmake is a cross-platform CMake script that adds dependency management capabilities to CMake.

It's built as a thin wrapper around CMake's [FetchContent](https://cmake.org/cmake/help/latest/module/FetchContent.html) module that adds version control, caching, a simple API [and more](#comparison-to-pure-fetchcontent--externalproject).



## Manage everything



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 the [snippets](#snippets) below for examples).



## Further reading



- [CPM: An Awesome Dependency Manager for C++ with CMake](https://medium.com/swlh/cpm-an-awesome-dependency-manager-for-c-with-cmake-3c53f4376766)

- [CMake and the Future of C++ Package Management](https://ibob.github.io/blog/2020/01/13/cmake-package-management/)



## Full CMakeLists Example



```cmake

cmake_minimum_required(VERSION 3.14 FATAL_ERROR)



# create project

project(MyProject)



# add executable

add_executable(main main.cpp)



# add dependencies

include(cmake/CPM.cmake)



CPMAddPackage("gh:fmtlib/fmt#7.1.3")

CPMAddPackage("gh:nlohmann/[email protected]")

CPMAddPackage("gh:catchorg/[email protected]")



# link dependencies

target_link_libraries(main fmt::fmt nlohmann_json::nlohmann_json Catch2::Catch2WithMain)

```



See the [examples directory](https://github.com/cpm-cmake/CPM.cmake/tree/master/examples) for complete examples with source code and check [below](#snippets) or in the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/More-Snippets) for example snippets.



## Adding CPM



To add CPM to your current project, simply add the [latest release](https://github.com/cpm-cmake/CPM.cmake/releases/latest) of `CPM.cmake` or `get_cpm.cmake` to your project's `cmake` directory.

The command below will perform this automatically.



```bash

mkdir -p cmake

wget -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's `CMakeLists.txt`. See the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/Downloading-CPM.cmake-in-CMake) for more details.



## Usage



After `CPM.cmake` has been [added](#adding-cpm) to your project, the function `CPMAddPackage` 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.



```cmake

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)

  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 a `GIT_REPOSITORY`, but other sources, such as direct URLs, are [also supported](https://cmake.org/cmake/help/v3.11/module/ExternalProject.html#external-project-definition).

If `GIT_TAG` hasn't been explicitly specified it defaults to `v(VERSION)`, a common convention for git projects.

On the other hand, if `VERSION` 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 as `master`, however this isn't recommended, as such packages will only be updated when the cache is cleared.



If an additional optional parameter `EXCLUDE_FROM_ALL` is set to a truthy value, then any targets defined inside the dependency won't be built by default. See the [CMake docs](https://cmake.org/cmake/help/latest/prop_tgt/EXCLUDE_FROM_ALL.html) for details.



If an additional optional parameter `SYSTEM` is set to a truthy value, the SYSTEM directory property of the subdirectory added will be set to true.

See the [add_subdirectory ](https://cmake.org/cmake/help/latest/command/add_subdirectory.html?highlight=add_subdirectory)

and [SYSTEM](https://cmake.org/cmake/help/latest/prop_tgt/SYSTEM.html#prop_tgt:SYSTEM) target property for details.



A single-argument compact syntax is also supported:



```cmake

# A git package from a given uri with a version

CPMAddPackage("uri@version")

# A git package from a given uri with a git tag or commit hash

CPMAddPackage("uri#tag")

# A git package with both version and tag provided

CPMAddPackage("uri@version#tag")

```



In the shorthand syntax if the URI is of the form `gh:user/name`, it is interpreted as GitHub URI and converted to `https://github.com/user/name.git`. If the URI is of the form `gl:user/name`, it is interpreted as a [GitLab](https://gitlab.com/explore/) URI and converted to `https://gitlab.com/user/name.git`. If the URI is of the form `bb:user/name`, it is interpreted as a [Bitbucket](https://bitbucket.org/) URI and converted to `https://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 the [EXCLUDE_FROM_ALL](https://cmake.org/cmake/help/latest/prop_tgt/EXCLUDE_FROM_ALL.html) and [SYSTEM](https://cmake.org/cmake/help/latest/prop_tgt/SYSTEM.html#prop_tgt:SYSTEM) flag.



The single-argument syntax also works for URLs:



```cmake

# An archive package from a given url. The version is inferred

CPMAddPackage("https://example.com/my-package-1.2.3.zip")

# An archive package from a given url with an MD5 hash provided

CPMAddPackage("https://example.com/my-package-1.2.3.zip#MD5=68e20f674a48be38d60e129f600faf7d")

# An archive package from a given url. The version is explicitly given

CPMAddPackage("https://example.com/[email protected]")

```



After calling `CPMAddPackage`, the following variables are defined in the local scope, where `` is the name of the dependency.



- `_SOURCE_DIR` is the path to the source of the dependency.

- `_BINARY_DIR` is the path to the build directory of the dependency.

- `_ADDED` is set to `YES` if the dependency has not been added before, otherwise it is set to `NO`.

- `CPM_LAST_PACKAGE_NAME` is set to the determined name of the last added dependency (equivalent to ``).



For using CPM.cmake projects with external package managers, such as conan or vcpkg, setting the variable [`CPM_USE_LOCAL_PACKAGES`](#options) will make CPM.cmake try to add a package through `find_package` first, and add it from source if it doesn't succeed.



In rare cases, this behaviour may be desirable by default. The function `CPMFindPackage` will try to find a local dependency via CMake's `find_package` and fallback to `CPMAddPackage`, if the dependency is not found.



## Updating CPM



To update CPM to the newest version, update the script in the project's root directory, for example by running the same command as for [adding CPM](#adding-cpm).

Dependencies using CPM will automatically use the updated script of the outermost project.



## Advantages



- **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.



## Limitations



- **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 the [`CPM_SOURCE_CACHE`](#CPM_SOURCE_CACHE) environmental variable. Using a caching compiler such as [ccache](https://github.com/TheLartians/Ccache.cmake) 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 snippets [below](#snippets) for examples). For best practices on preparing projects for CPM, see the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/Preparing-projects-for-CPM.cmake).

- **First version used** In diamond-shaped dependency graphs (e.g. `A` depends on `C`@1.1 and `B`, which itself depends on `C`@1.2 the first added dependency will be used (in this case `C`@1.1). In this case, B requires a newer version of `C` than `A`, 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 a [package lock file](#package-lock).

- **Some CMake policies set to `NEW`** Including CPM.cmake will lead to several CMake policies being set to `NEW`. Users which need the old behavior will need to manually modify their CMake code to ensure they're set to `OLD` at the appropriate places. The policies are:

    - [CMP0077](https://cmake.org/cmake/help/latest/policy/CMP0077.html) and [CMP0126](https://cmake.org/cmake/help/latest/policy/CMP0126.html). They make setting package options from `CMPAddPackage` possible.

    - [CMP0135](https://cmake.org/cmake/help/latest/policy/CMP0135.html) 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](https://cmake.org/cmake/help/latest/policy/CMP0150.html) Relative paths provided to `GIT_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 as [vcpkg](https://github.com/microsoft/vcpkg), [conan](https://conan.io) or [hunter](https://github.com/ruslo/hunter).

Dependencies added with `CPMFindPackage` should work with external package managers.

Additionally, the option [`CPM_USE_LOCAL_PACKAGES`](#cpmuselocalpackages) will enable `find_package` for all CPM dependencies.



## Comparison to FindPackage



The usual way to add libraries in CMake projects is to call `find_package()` and to link against libraries defined in a `_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 from `find_package`, as variables exported to the parent scope (such as  `_LIBRARIES`) will not be visible after adding a package using CPM.cmake.

The behaviour can be [achieved manually](https://github.com/cpm-cmake/CPM.cmake/issues/132#issuecomment-644955140), if required.



## Comparison to pure FetchContent / ExternalProject



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 dependencies [are available locally](#cpm_source_cache).

- Automatic shallow clone: if a version tag (e.g. `v2.2.0`) is provided and `CPM_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: all `CPMAddPackage` can be configured to use `find_package` by setting a [CMake flag](#cpm_use_local_packages), making it easy to integrate into projects that may require local versioning through the system's package manager.

- [Package lock files](#package-lock) for easier transitive dependency management.

- Dependencies can be overridden [per-build](#local-package-override) 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.



## Options



### CPM_SOURCE_CACHE



To avoid re-downloading dependencies, CPM has an option `CPM_SOURCE_CACHE` that can be passed to CMake as `-DCPM_SOURCE_CACHE=`.

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 exporting `CPM_SOURCE_CACHE` in your `.bashrc` or `.bash_profile`.



```bash

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 use `CPM_SOURCE_CACHE` on GitHub Actions workflows [cache](https://github.com/actions/cache) and combine it with ccache, to make your CI faster. See the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/Caching-with-CPM.cmake-and-ccache-on-GitHub-Actions) for more info.



### CPM_DOWNLOAD_ALL



If set, CPM will forward all calls to `CPMFindPackage` as `CPMAddPackage`.

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 the `CPM_DOWNLOAD_` variable.



### CPM_USE_LOCAL_PACKAGES



CPM can be configured to use `find_package` to search for locally installed dependencies first by setting the CMake option `CPM_USE_LOCAL_PACKAGES`.



If the option `CPM_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 that `find_package` requires additional arguments, the parameter `FIND_PACKAGE_ARGUMENTS` may be specified in the `CPMAddPackage` call. The value of this parameter will be forwarded to `find_package`.



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



### CPM_USE_NAMED_CACHE_DIRECTORIES



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.



## Local package override



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 option `CPM__SOURCE` set to the absolute path of the local library.

For example, to use the local version of the dependency `Dep` at the path `/path/to/dep`, the consumer can be built with the following command.



```bash

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

```



## Package lock



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 original `CMakeLists.txt`.

To use a package lock, add the following line directly after including CPM.cmake.



```cmake

CPMUsePackageLock(package-lock.cmake)

```



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



```bash

cmake -Bbuild

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

```



See the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/Package-lock) for more info.



## Private repositories and CI



When using CPM.cmake with private repositories, there may be a need to provide an [access token](https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/creating-a-personal-access-token) to be able to clone other projects. Instead of providing the token in CMake, we recommend to provide the regular URL and use [git-config](https://git-scm.com/docs/git-config) to rewrite the URLs to include the token.



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



```bash

# Github

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

```



```bash

# GitLab

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

```



## Built with CPM.cmake



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.



  

    

      

        


          otto-project

        


        
OTTO - The Open Source GrooveBox


      

    

    

      

        


          maphi

        


        
Maphi - the Math App


      

    

    

      

        


          modern-cpp-starter

        


        
ModernCppStarter


      

    

  

  

    

      

        


          liblava

        


        
liblava - Modern Vulkan library


      

    

    

      

        


          klogg

        


        
klogg - fast advanced log explorer


      

    

    

      

        


          MethaneKit

        


        
Methane Kit - modern 3D graphics rendering framework


      

    

  

  

    

      

        


          JNGL

        


        
JNGL - easy to use cross-platform 2D game library


      

    

    

      

        


          aaltitoad

        


        
AALTITOAD - verifier and simulator for Tick Tock Automata


      

    

    

      

        


          ZIMO-Elektronik

        


        
ZIMO-Elektronik


      

    

  

  

    

      

        


          ada

        


        
ada - WHATWG-compliant and fast URL parser written in modern C++


      

    

    

      

        


          codon

        


        
codon - A high-performance, zero-overhead, extensible Python compiler using LLVM


      

    

    

      

        


          CRoaring

        


        
CRoaring - Roaring bitmaps in C (and C++), with SIMD (AVX2, AVX-512 and NEON) optimizations: used by Apache Doris, ClickHouse, and StarRocks


      

    

  



## Snippets



These examples demonstrate how to include some well-known projects with CPM.

See the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/More-Snippets) for more snippets.



### [Catch2](https://github.com/catchorg/Catch2)



```cmake

CPMAddPackage("gh:catchorg/[email protected]")

```



### [Range-v3](https://github.com/ericniebler/range-v3)



```Cmake

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

```



### [Yaml-cpp](https://github.com/jbeder/yaml-cpp)



```CMake

# as the tag is in an unusual format, we need to explicitly specify the version

CPMAddPackage("gh:jbeder/yaml-cpp#[email protected]")

```



### [nlohmann/json](https://github.com/nlohmann/json)



```cmake

CPMAddPackage(

  NAME nlohmann_json

  VERSION 3.9.1

  GITHUB_REPOSITORY nlohmann/json

  OPTIONS

    "JSON_BuildTests OFF"

)

```



### [Boost ](https://github.com/boostorg/boost)



```CMake

# boost is a huge project and will take a while to download

# using `CPM_SOURCE_CACHE` is strongly recommended

CPMAddPackage(

  NAME Boost

  VERSION 1.81.0

  GITHUB_REPOSITORY "boostorg/boost"

  GIT_TAG "boost-1.81.0"

)

```



### [cxxopts](https://github.com/jarro2783/cxxopts)



```cmake

# the install option has to be explicitly set to allow installation

CPMAddPackage(

  GITHUB_REPOSITORY jarro2783/cxxopts

  VERSION 2.2.1

  OPTIONS "CXXOPTS_BUILD_EXAMPLES NO" "CXXOPTS_BUILD_TESTS NO" "CXXOPTS_ENABLE_INSTALL YES"

)

```



### [google/benchmark](https://github.com/google/benchmark)



```cmake

CPMAddPackage(

  NAME benchmark

  GITHUB_REPOSITORY google/benchmark

  VERSION 1.5.2

  OPTIONS "BENCHMARK_ENABLE_TESTING Off"

)



if(benchmark_ADDED)

  # enable c++11 to avoid compilation errors

  set_target_properties(benchmark PROPERTIES CXX_STANDARD 11)

endif()

```



### [Lua](https://www.lua.org)



```cmake

CPMAddPackage(

  NAME lua

  GIT_REPOSITORY https://github.com/lua/lua.git

  VERSION 5.3.5

  DOWNLOAD_ONLY YES

)



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(lua STATIC ${lua_sources})



  target_include_directories(lua

    PUBLIC

      $

  )

endif()

```



For a full example on using CPM to download and configure lua with sol2 see [here](examples/sol2).



### Full Examples



See the [examples directory](https://github.com/cpm-cmake/CPM.cmake/tree/master/examples) for full examples with source code and check out the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/More-Snippets) for many more example snippets.