vcpkg in CMake projects

مقالة
01/10/2024

vcpkg offers seamless integration with CMake to make installed packages available in your projects automatically. The mechanism in which vcpkg integrates is by providing a CMake toolchain file.

The first time CMake configures a project, it runs internal search routines to locate a viable toolchain (compiler, linker, etc.). This search happens within the project() function in your CMakeLists.txt.

To customize the toolchain selection process, CMake supports using custom CMake-language scripts, known as toolchain files. A toolchain file is specified by setting the CMAKE_TOOLCHAIN_FILE variable. CMake evaluates the contents of the provided toolchain script and sets variable definitions, paths to required build tools, and other build parameters, such as cross-compilation flags, accordingly.

When you set CMAKE_TOOLCHAIN_FILE to use the vcpkg toolchain (<vcpkg-root>/scripts/buildsystems/vcpkg.cmake), vcpkg takes advantage of the toolchain file mechanism to inject code to integrate with built-in CMake functions transparently to you.

You can still use a toolchain file to configure your own toolsets by using the VCPKG_CHAINLOAD_TOOLCHAIN_FILE triplet variable.

The vcpkg integration works differently depending on the operation mode you're using:

In classic mode, vcpkg sets CMake search paths appropriately to make installed packages available via the find_package(), find_library(), and find_path() functions.

In manifest mode, in addition to the above, the toolchain detects manifest files (vcpkg.json files) and runs vcpkg install to automatically acquire the project's dependencies.

Because the toolchain file is evaluated during the project() call, all CMake-level variables that modify a vcpkg setting must be set before the first call to project(). It may also be necessary to reconfigure your CMake project if you modify any vcpkg setting that results in ABI hash changes.

See Installing and Using Packages Example: sqlite for a fully worked example using CMake.

`CMAKE_TOOLCHAIN_FILE`

Note

If you set CMAKE_TOOLCHAIN_FILE in your CMakeList.txt file, make sure that the variable is set before any calls to project().

Projects configured to use the vcpkg toolchain file (via the CMake setting CMAKE_TOOLCHAIN_FILE) can find libraries from vcpkg using the standard CMake functions: find_package(), find_path(), and find_library().

We recommend using CMake Presets to specify your toolchain file. For example, if you have defined the environment variable VCPKG_ROOT, you can use the following CMakePresets.json and pass --preset debug on the configure line:

{
  "version": 2,

  "configurePresets": [
    {
      "name": "debug",
      "cacheVariables": {
        "CMAKE_TOOLCHAIN_FILE": "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake"
      }
    }
  ]
}

cmake -B build -S /my/project --preset debug

If you need to use an absolute path for vcpkg specific to your current machine, you can use CMakeUserPresets.json and add it to your .gitignore file.

{
  "version": 2,

  "configurePresets": [
    {
      "name": "debug",
      "cacheVariables": {
        "CMAKE_TOOLCHAIN_FILE": "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake"
      }
    }
  ]
}

CMake versions older than 3.19 must pass the toolchain file on the configure command line:

cmake ../my/project -DCMAKE_TOOLCHAIN_FILE=<vcpkg-root>/scripts/buildsystems/vcpkg.cmake

Using Libraries

vcpkg supports CMake's native mechanisms for finding libraries: find_package(), find_library(), and find_path(). When installing libraries with specific CMake support, vcpkg will display usage information on how to consume the library:

The package zlib is compatible with built-in CMake targets:

    find_package(ZLIB REQUIRED)
    target_link_libraries(main PRIVATE ZLIB::ZLIB)

vcpkg does not automatically add any include or links paths into your project. To use a header-only library you can use find_path() which will correctly work on all platforms:

# To find and use catch2
find_path(CATCH_INCLUDE_DIR NAMES catch.hpp PATH_SUFFIXES catch2)
target_include_directories(main PRIVATE ${CATCH_INCLUDE_DIR})

IDE Integration

Visual Studio / Visual Studio Code

We recommend using CMake Presets in both Visual Studio and Visual Studio Code.

Learn more at Configure and build with CMake Presets in Visual Studio and Configure and build with CMake Presets in Visual Studio Code.

CLion

Open the Toolchains settings (File > Settings on Windows and Linux, CLion > Preferences on macOS), and go to the CMake settings (Build, Execution, Deployment > CMake). In CMake options, add the following line:

-DCMAKE_TOOLCHAIN_FILE=<vcpkg-root>/scripts/buildsystems/vcpkg.cmake

You must add this line to each profile separately.

Using Multiple Toolchain Files

To combine vcpkg's toolchain file with another toolchain file, you can set the CMake cache variable VCPKG_CHAINLOAD_TOOLCHAIN_FILE:

cmake ../my/project \
   -DCMAKE_TOOLCHAIN_FILE=C:/vcpkg/scripts/buildsystems/vcpkg.cmake \
   -DVCPKG_CHAINLOAD_TOOLCHAIN_FILE=../my/project/toolchain.cmake

Alternatively, you can include the vcpkg toolchain at the end of the primary toolchain file:

# MyToolchain.cmake
set(CMAKE_CXX_COMPILER ...)
set(VCPKG_TARGET_TRIPLET x64-my-custom-windows-triplet)
include(/path/to/vcpkg/scripts/buildsystems/vcpkg.cmake)

Note

vcpkg does not automatically apply your toolchain's settings, such as your compiler or compilation flags, while building libraries. To change vcpkg's library settings, you must make a custom triplet file (which can share your toolchain)**

Settings Reference

All vcpkg-affecting variables must be defined before the first project() directive such as in a CMakePresets.json's "cacheVariables" map, via the command line, or set() statements.

`VCPKG_TARGET_TRIPLET`

This setting controls the triplet vcpkg will install and consume libraries from.

If unset, vcpkg will automatically detect an appropriate default triplet given the current compiler settings. If you change this CMake variable, you must delete your cache and reconfigure.

`VCPKG_HOST_TRIPLET`

This variable controls which triplet host dependencies will be installed for.

If unset, vcpkg will automatically detect an appropriate native triplet (x64-windows, x64-osx, x64-linux).

`VCPKG_INSTALLED_DIR`

This variable sets the location where libraries will be installed and consumed from.

In manifest mode, the default is ${CMAKE_BINARY_DIR}/vcpkg_installed.

In classic mode, the default is ${VCPKG_ROOT}/installed.

`VCPKG_MANIFEST_MODE`

This variable forces vcpkg to operate in either manifest mode or classic mode.

Defaults to ON when VCPKG_MANIFEST_DIR is non-empty or ${CMAKE_SOURCE_DIR}/vcpkg.json exists.

To disable manifest mode while a vcpkg.json is detected, set this to OFF.

`VCPKG_MANIFEST_DIR`

This variable specifies an alternate folder containing a vcpkg.json manifest.

Defaults to ${CMAKE_SOURCE_DIR} if ${CMAKE_SOURCE_DIR}/vcpkg.json exists.

`VCPKG_MANIFEST_INSTALL`

This variable controls whether vcpkg will be automatically run to install your dependencies during your configure step.

Defaults to ON if VCPKG_MANIFEST_MODE is ON.

`VCPKG_BOOTSTRAP_OPTIONS`

This variable can be set to additional command parameters to pass to ./bootstrap-vcpkg.

In manifest mode, vcpkg will be automatically bootstrapped if the executable does not exist.

`VCPKG_OVERLAY_TRIPLETS`

This variable can be set to a list of paths to be passed on the command line as --overlay-triplets=...

`VCPKG_OVERLAY_PORTS`

This variable can be set to a list of paths to be passed on the command line as --overlay-ports=...

`VCPKG_MANIFEST_FEATURES`

This variable can be set to a list of features to activate when installing from your manifest.

For example, features can be used by projects to control building with additional dependencies to enable tests or samples:

{
  "name": "mylibrary",
  "version": "1.0",
  "dependencies": [ "curl" ],
  "features": {
    "samples": {
      "description": "Build Samples",
      "dependencies": [ "fltk" ]
    },
    "tests": {
      "description": "Build Tests",
      "dependencies": [ "gtest" ]
    }
  }
}

This setting can be controlled directly by CMake Presets with "cacheVariables" or indirectly based on other settings:

# CMakeLists.txt

option(BUILD_TESTING "Build tests" OFF)
if(BUILD_TESTING)
  list(APPEND VCPKG_MANIFEST_FEATURES "tests")
endif()

option(BUILD_SAMPLES "Build samples" OFF)
if(BUILD_SAMPLES)
  list(APPEND VCPKG_MANIFEST_FEATURES "samples")
endif()

project(myapp)

# ...

`VCPKG_MANIFEST_NO_DEFAULT_FEATURES`

This variable controls activation of default features in addition to those listed in VCPKG_MANIFEST_FEATURES. If set to ON, default features will not be automatically activated.

Defaults to OFF.

`VCPKG_INSTALL_OPTIONS`

This variable can be set to a list of additional command line parameters to pass to the vcpkg tool during automatic installation.

`VCPKG_PREFER_SYSTEM_LIBS`

Warning

This feature has been deprecated. Use empty overlay ports instead.

This variable controls whether vcpkg will append instead of prepend its paths to CMAKE_PREFIX_PATH, CMAKE_LIBRARY_PATH and CMAKE_FIND_ROOT_PATH so that vcpkg libraries/packages are found after toolchain/system libraries/packages.