cmake_layout

The cmake_layout() sets the folders and cpp attributes to follow the structure of a typical CMake project.

from conan.tools.cmake import cmake_layout

def layout(self):
    cmake_layout(self)

Note

To try it you can use the conan new -d name=hello -d version=1.0 cmake_lib template.

The assigned values depend on the CMake generator that will be used. It can be defined with the tools.cmake.cmaketoolchain:generator [conf] entry or passing it in the recipe to the cmake_layout(self, cmake_generator) function. The assigned values are different if it is a multi-config generator (like Visual Studio or Xcode), or a single-config generator (like Unix Makefiles).

These are the values assigned by the cmake_layout:

  • conanfile.folders.source: src_folder argument or . if not specified.

  • conanfile.folders.build:

    • build: if the cmake generator is multi-configuration.

    • build/Debug or build/Release: if the cmake generator is single-configuration, depending on the build_type.

    • The "build" string, can be defined to other value by the build_folder argument.

  • conanfile.folders.generators: build/generators

  • conanfile.cpp.source.includedirs: ["include"]

  • conanfile.cpp.build.libdirs and conanfile.cpp.build.bindirs:

    • ["Release"] or ["Debug"] for a multi-configuration cmake generator.

    • . for a single-configuration cmake generator.

Reference

cmake_layout(conanfile, generator=None, src_folder='.', build_folder='build')
Parameters:

  • conanfile – The current recipe object. Always use self.

  • generator – Allow defining the CMake generator. In most cases it doesn’t need to be passed, as it will get the value from the configuration tools.cmake.cmaketoolchain:generator, or it will automatically deduce the generator from the settings

  • src_folder – Value for conanfile.folders.source, change it if your source code (and CMakeLists.txt) is in a subfolder.

  • build_folder – Specify the name of the “base” build folder. The default is “build”, but if that folder name is used by the project, a different one can be defined

Multi-setting/option cmake_layout

The folders.build and conanfile.folders.generators can be customized to take into account the settings and options and not only the build_type. Use the tools.cmake.cmake_layout:build_folder_vars conf to declare a list of settings or options:

conan install . -c tools.cmake.cmake_layout:build_folder_vars="['settings.compiler', 'options.shared']"

For the previous example, the values assigned by the cmake_layout (installing the Release/static default configuration) would be:

  • conanfile.folders.build:

    • build/apple-clang-shared_false: if the cmake generator is multi-configuration.

    • build/apple-clang-shared_false/Debug: if the cmake generator is single-configuration.

  • conanfile.folders.generators: build/generators

If we repeat the previous install with a different configuration:

conan install . -o shared=True -c tools.cmake.cmake_layout:build_folder_vars="['settings.compiler', 'options.shared']"

The values assigned by the cmake_layout (installing the Release/shared configuration) would be:

  • conanfile.folders.build:

    • build/apple-clang-shared_true: if the cmake generator is multi-configuration.

    • build/apple-clang-shared_true/Debug: if the cmake generator is single-configuration.

  • conanfile.folders.generators: build-apple-clang-shared_true/generators

So we can keep separated folders for any number of different configurations that we want to install.

The CMakePresets.json file generated at the CMakeToolchain generator, will also take this tools.cmake.cmake_layout:build_folder_vars config into account to generate different names for the presets, being very handy to install N configurations and building our project for any of them by selecting the chosen preset.