CMake¶

The CMake build helper is a wrapper around the command line invocation of cmake. It will abstract the calls like cmake --build . --config Release into Python method calls. It will also add the argument -DCMAKE_TOOLCHAIN_FILE=conan_toolchain.cmake (from the generator CMakeToolchain) to the configure() call, as well as other possible arguments like -DCMAKE_BUILD_TYPE=<config>. The arguments that will be used are obtained from a generated CMakePresets.json file.

The helper is intended to be used in the build() method, to call CMake commands automatically when a package is being built directly by Conan (create, install)

from conan import ConanFile
from conan.tools.cmake import CMake, CMakeToolchain, CMakeDeps

class App(ConanFile):
    settings = "os", "arch", "compiler", "build_type"
    requires = "hello/0.1"
    options = {"shared": [True, False], "fPIC": [True, False]}
    default_options = {"shared": False, "fPIC": True}

    def generate(self):
        tc = CMakeToolchain(self)
        tc.generate()
        deps = CMakeDeps(self)
        deps.generate()

    def build(self):
        cmake = CMake(self)
        cmake.configure()
        cmake.build()

Experimental feature. CMake.configure(), CMake.build() and CMake.install() methods have the subfolder parameter in case you have more than one CMakeLists.txt in different folders. This feature allows you to call the configure build and install method of each CMakeLists.txt separately and without mixing the generated files and artifacts, also creating these folders in the build folder and package folder.

In the following example, we can see what it would look like if we had two different CMakeLists.txt (cmake_1/CMakeLists.txt and cmake_2/CMakeLists.txt) in the folder1 and folder2 folders.

def build(self):
    cmake = CMake(self)

    # Configure and build source_folder/cmake_1/CMakeLists.txt in folder1
    cmake.configure(build_script_folder="cmake_1", subfolder="folder1")
    cmake.build(subfolder="folder1")

    # Configure and build source_folder/cmake_2/CMakeLists.txt in folder2
    cmake.configure(build_script_folder="cmake_2" subfolder="folder2")
    cmake.build(subfolder="folder2")

Reference¶

class CMake(conanfile)¶

CMake helper to use together with the CMakeToolchain feature

Parameters:: conanfile – The current recipe object. Always use self.

configure(variables=None, build_script_folder=None, cli_args=None, stdout=None, stderr=None, subfolder=None)¶

Reads the CMakePresets.json file generated by the CMakeToolchain to get:

The generator, to append -G="xxx".

The path to the toolchain and append -DCMAKE_TOOLCHAIN_FILE=/path/conan_toolchain.cmake

The declared cache variables and append -Dxxx.

and call cmake.

Parameters:

variables – Should be a dictionary of CMake variables and values, that will be mapped to command line -DVAR=VALUE arguments. Recall that in the general case information to CMake should be passed in CMakeToolchain to be provided in the conan_toolchain.cmake file. This variables argument is intended for exceptional cases that wouldn’t work in the toolchain approach.
build_script_folder – Path to the CMakeLists.txt in case it is not in the declared self.folders.source at the layout() method.
cli_args – List of arguments [arg1, arg2, ...] that will be passed as extra CLI arguments to pass to cmake invocation
subfolder – (Experimental): The name of a subfolder to be created inside the build_folder and the package_folder. If not provided, files will be placed in the build_folder and the package_folder root.
stdout – Use it to redirect stdout to this stream
stderr – Use it to redirect stderr to this stream

build(build_type=None, target=None, cli_args=None, build_tool_args=None, stdout=None, stderr=None, subfolder=None)¶

Parameters:

build_type – Use it only to override the value defined in the settings.build_type for a multi-configuration generator (e.g. Visual Studio, XCode). This value will be ignored for single-configuration generators, they will use the one defined in the toolchain file during the install step.
target – The name of a single build target as a string, or names of multiple build targets in a list of strings to be passed to the --target argument.
cli_args – A list of arguments [arg1, arg2, ...] that will be passed to the cmake --build ... arg1 arg2 command directly.
build_tool_args – A list of arguments [barg1, barg2, ...] for the underlying build system that will be passed to the command line after the -- indicator: cmake --build ... -- barg1 barg2
subfolder – (Experimental): The name of a subfolder to be created inside the build_folder and the package_folder. If not provided, files will be placed in the build_folder and the package_folder root.
stdout – Use it to redirect stdout to this stream
stderr – Use it to redirect stderr to this stream

install(build_type=None, component=None, cli_args=None, stdout=None, stderr=None, subfolder=None)¶

Equivalent to running cmake --install

Parameters:

component – The specific component to install, if any
build_type – Use it only to override the value defined in the settings.build_type. It can fail if the build is single configuration (e.g. Unix Makefiles), as in that case the build type must be specified at configure time, not build type.
cli_args – A list of arguments [arg1, arg2, ...] for the underlying build system that will be passed to the command line: cmake --install ... arg1 arg2
subfolder – (Experimental): The name of a subfolder to be created inside the build_folder and the package_folder. If not provided, files will be placed in the build_folder and the package_folder root.
stdout – Use it to redirect stdout to this stream
stderr – Use it to redirect stderr to this stream

test(build_type=None, target=None, cli_args=None, build_tool_args=None, env='', stdout=None, stderr=None)¶

Equivalent to running cmake –build . –target=RUN_TESTS.

Parameters:

build_type – Use it only to override the value defined in the settings.build_type. It can fail if the build is single configuration (e.g. Unix Makefiles), as in that case the build type must be specified at configure time, not build time.
target – Name of the build target to run, by default RUN_TESTS or test
cli_args – Same as above build(), a list of arguments [arg1, arg2, ...] to be passed as extra arguments for the underlying build system
build_tool_args – Same as above build()
stdout – Use it to redirect stdout to this stream
stderr – Use it to redirect stderr to this stream

ctest(cli_args=None, env='', stdout=None, stderr=None)¶

Equivalent to running ctest …

Parameters:

cli_args – List of arguments [arg1, arg2, ...] to be passed as extra ctest command line arguments
env – the environment files to activate, by default conanbuild + conanrun
stdout – Use it to redirect stdout to this stream
stderr – Use it to redirect stderr to this stream

conf¶

The CMake() build helper is affected by these [conf] variables:

tools.build:verbosity will accept one of quiet or verbose to be passed to the CMake.build() command, when a Visual Studio generator (MSBuild build system) is being used for CMake. It is passed as an argument to the underlying build system via the call cmake --build . --config Release -- /verbosity:Diagnostic
tools.compilation:verbosity will accept one of quiet or verbose to be passed to CMake, which sets -DCMAKE_VERBOSE_MAKEFILE if verbose
tools.build:jobs argument for the --jobs parameter when running Ninja generator.
tools.microsoft.msbuild:max_cpu_count argument for the /m (/maxCpuCount) when running MSBuild. If max_cpu_count=0, then it will use /m without arguments, which means use all available cpus.
tools.cmake:cmake_program specify the location of the CMake executable, instead of using the one found in the PATH.
tools.cmake:install_strip (deprecated use tools.build:install_strip) will pass --strip to the cmake --install call if set to True.
tools.build:install_strip (Since Conan 2.18.0) will pass --strip to the cmake --install call if set to True.