CMakeDeps

Important

Some of the features used in this section are still under development, while they are recommended and usable and we will try not to break them in future releases, some breaking changes might still happen if necessary to prepare for the Conan 2.0 release.

Available since: 1.33.0

The CMakeDeps helper will generate one xxxx-config.cmake file per dependency, together with other necessary .cmake files like version, flags and directory data or configuration. It can be used like:

from conan import ConanFile

class App(ConanFile):
    settings = "os", "arch", "compiler", "build_type"
    requires = "hello/0.1"
    generators = "CMakeDeps"

The full instantiation, that allows custom configuration can be done in the generate() method:

from conan import ConanFile
from conan.tools.cmake import CMakeDeps

class App(ConanFile):
    settings = "os", "arch", "compiler", "build_type"
    requires = "hello/0.1"

    def generate(self):
        cmake = CMakeDeps(self)
        cmake.generate()

Important

This class will require very soon to define both the “host” and “build” profiles. It is very recommended to start defining both profiles immediately to avoid future breaking. Furthermore, some features, like trying to cross-compile might not work at all if the “build” profile is not provided.

The CMakeDeps is a multi-configuration generator, it can correctly create files for Release/Debug configurations to be simultaneously used by IDEs like Visual Studio. In single configuration environments, it is necessary to have a configuration defined, which must be provided via the cmake ... -DCMAKE_BUILD_TYPE=<build-type> argument in command line (Conan will do it automatically when necessary, in the CMake.configure() helper).

There are some attributes you can adjust in the created CMakeDeps object to change the default behavior:

configuration

Allows to define custom user CMake configuration besides the standard Release, Debug, etc ones.

def generate(self):
    deps = CMakeDeps(self)
    # By default, ``deps.configuration`` will be ``self.settings.build_type``
    if self.options["hello"].shared:
        # Assuming the current project ``CMakeLists.txt`` defines the ReleasedShared configuration.
        deps.configuration = "ReleaseShared"
    deps.generate()

build_context_activated

When you have a build-require, by default, the config files (xxx-config.cmake) files are not generated. But you can activate it using the build_context_activated attribute:

tool_requires = ["my_tool/0.0.1"]

def generate(self):
    cmake = CMakeDeps(self)
    # generate the config files for the tool require
    cmake.build_context_activated = ["my_tool"]
    cmake.generate()

Warning

The build_context_activated feature will fail if no “build” profile is used. This feature only work when using the two host and build profiles.

build_context_suffix

When you have the same package as a build-require and as a regular require it will cause a conflict in the generator because the file names of the config files will collide as well as the targets names, variables names etc.

For example, this is a typical situation with some requirements (capnproto, protobuf…) that contain a tool used to generate source code at build time (so it is a build_require), but also providing a library to link to the final application, so you also have a regular require. Solving this conflict is specially important when we are cross-building because the tool (that will run in the building machine) belongs to a different binary package than the library, that will “run” in the host machine.

You can use the build_context_suffix attribute to specify a suffix for a requirement, so the files/targets/variables of the requirement in the build context (tool require) will be renamed:

tool_requires = ["my_tool/0.0.1"]
requires = ["my_tool/0.0.1"]

def generate(self):
    cmake = CMakeDeps(self)
    # generate the config files for the tool require
    cmake.build_context_activated = ["my_tool"]
    # disambiguate the files, targets, etc
    cmake.build_context_suffix = {"my_tool": "_BUILD"}
    cmake.generate()

Warning

The build_context_suffix feature will fail if no “build” profile is used. This feature only work when using the two host and build profiles.

build_context_build_modules

Also there is another issue with the build_modules. As you may know, the recipes of the requirements can declare a cppinfo.build_modules entry containing one or more .cmake files. When the requirement is found by the cmake find_package() function, Conan will include automatically these files.

By default, Conan will include only the build modules from the host context (regular requires) to avoid the collision, but you can change the default behavior.

Use the build_context_build_modules attribute to specify require names to include the build_modules from tool_requires:

tool_requires = ["my_tool/0.0.1"]

def generate(self):
    cmake = CMakeDeps(self)
    # generate the config files for the tool require
    cmake.build_context_activated = ["my_tool"]
    # Choose the build modules from "build" context
    cmake.build_context_build_modules = ["my_tool"]
    cmake.generate()

Warning

The build_context_build_modules feature will fail if no “build” profile is used. This feature only work when using the two host and build profiles.

set_property()

Since Conan 1.55.0 .

def set_property(self, dep, prop, value, build_context=False):

dep: Name of the dependency to set the property. For components use the syntax: dep_name::component_name.
prop: Name of the property.
value: Value of the property. Use None to invalidate any value set by the upstream recipe.
build_context: Set to True if you want to set the property for a dependency that belongs to the build context (False by default).

Using this method you can overwrite the property values set by the Conan recipes from the consumer. This can be done for cmake_file_name, cmake_target_name, cmake_find_mode, cmake_module_file_name and cmake_module_target_name properties. Let’s see an example of how this works:

Imagine we have a compressor/1.0 package that depends on zlib/1.2.11. The zlib recipe defines some properties:

Zlib conanfile.py

class ZlibConan(ConanFile):
    name = "zlib"

    ...

    def package_info(self):
        self.cpp_info.set_property("cmake_find_mode", "both")
        self.cpp_info.set_property("cmake_file_name", "ZLIB")
        self.cpp_info.set_property("cmake_target_name", "ZLIB::ZLIB")
        ...

This recipe defines several properties. For example the cmake_find_mode property is set to both. That means that module and config files are generated for Zlib. Maybe we need to alter this behaviour and just generate config files. You could do that in the compressor recipe using the CMakeDeps.set_property() method:

compressor conanfile.py

class Compressor(ConanFile):
    name = "compressor"

    requires = "zlib/1.2.11"
    ...

    def generate(self):
        deps = CMakeDeps(self)
        deps.set_property("zlib", "cmake_find_mode", "config")
        deps.generate()
        ...

You can also use the set_property() method to invalidate the property values set by the upstream recipe and use the values that Conan assigns by default. To do so, set the value None to the property like this:

compressor conanfile.py

class Compressor(ConanFile):
    name = "compressor"

    requires = "zlib/1.2.11"
    ...

    def generate(self):
        deps = CMakeDeps(self)
        deps.set_property("zlib", "cmake_target_name", None)
        deps.generate()
        ...

After doing this the generated target name for the Zlib library will be zlib::zlib instead of ZLIB::ZLIB

Properties

The following properties affect the CMakeDeps generator:

cmake_file_name: The config file generated for the current package will follow the <VALUE>-config.cmake pattern, so to find the package you write find_package(<VALUE>).
cmake_target_name: Name of the target to be consumed.
cmake_target_aliases: List of aliases that Conan will create for an already existing target.
cmake_find_mode: Defaulted to config. Possible values are:
- config: The CMakeDeps generator will create config scripts for the dependency.
- module: Will create module config (FindXXX.cmake) scripts for the dependency.
- both: Will generate both config and modules.
- none: Won’t generate any file. It can be used, for instance, to create a system wrapper package so the consumers find the config files in the CMake installation config path and not in the generated by Conan (because it has been skipped).
cmake_module_file_name: Same as cmake_file_name but when generating modules with cmake_find_mode=module/both. If not specified it will default to cmake_file_name.
cmake_module_target_name: Same as cmake_target_name but when generating modules with cmake_find_mode=module/both. If not specified it will default to cmake_target_name.
cmake_build_modules: List of .cmake files (route relative to root package folder) that are automatically included when the consumer run the find_package(). This property can’t be declared in a component, do it in the global self.cpp_info.
cmake_set_interface_link_directories: boolean value that should be only used by dependencies that don’t declare self.cpp_info.libs but have #pragma comment(lib, "foo") (automatic link) declared at the public headers. Those dependencies should add this property to their conanfile.py files at root cpp_info level (components not supported for now).

Example:

def package_info(self):
    ...
    # MyFileName-config.cmake
    self.cpp_info.set_property("cmake_file_name", "MyFileName")
    # Names for targets are absolute, Conan won't add any namespace to the target names automatically
    self.cpp_info.set_property("cmake_target_name", "Foo::Foo")

    # Create a new target "MyFooAlias" that is an alias to the "Foo::Foo" target
    self.cpp_info.set_property("cmake_target_aliases", ["MyFooAlias"])
    # The property "cmake_build_modules" can't be declared in a component, do it in self.cpp_info
    self.cpp_info.set_property("cmake_build_modules", [os.path.join("lib", "mypkg.cmake")])

    self.cpp_info.components["mycomponent"].set_property("cmake_target_name", "Foo::Var")

    # Create a new target "VarComponent" that is an alias to the "Foo::Var" component target
    self.cpp_info.components["mycomponent"].set_property("cmake_target_aliases", ["VarComponent"])

    # Skip this package when generating the files for the whole dependency tree in the consumer
    # note: it will make useless the previous adjustments.
    # self.cpp_info.set_property("cmake_find_mode", "none")

    # Generate both MyFileNameConfig.cmake and FindMyFileName.cmake
    self.cpp_info.set_property("cmake_find_mode", "both")

Disable CMakeDeps For Installed CMake configuration files

Some projects may want to disable the CMakeDeps generator for downstream consumers. This can be done by settings cmake_find_mode to none. If the project wants to provide it’s own configuration targets, it should append them to the buildirs attribute of cpp_info.

This method is intended to work with downstream consumers using the CMakeToolchain generator, which will be populated with the builddirs attribute.

Example:

def package(self):
    ...
    cmake.install()

def package_info(self):
    self.cpp_info.set_property("cmake_find_mode", "none") # Do NOT generate anyfiles
    self.cpp_info.builddirs.append(os.path.join("lib", "cmake", "foo"))

Map from project configuration to imported target’s configuration

As mentioned above, CMakeDeps provides support for multiple configuration environments (Debug, Release, etc.) This is achieved by populating properties on the imported targets according to the build_type setting when installing dependencies. When a consumer project is configured with a single-configuration CMake generator, however, it is necessary to define the CMAKE_BUILD_TYPE with a value that matches that of the installed dependencies.

If the consumer CMake project is configured with a different build type than the dependencies, it is necessary to tell CMake how to map the configurations from the current project to the imported targets by setting the CMAKE_MAP_IMPORTED_CONFIG_<CONFIG> CMake variable.

cd build-coverage/
conan install .. -s build_type=Debug
cmake .. -DCMAKE_BUILD_TYPE=Coverage -DCMAKE_TOOLCHAIN_FILE=<path>/conan_toolchain.cmake -DCMAKE_MAP_IMPORTED_CONFIG_COVERAGE=Debug