build_folder_vars consts (#3800)

Author: memsharded

reference/tools/cmake/cmake_layout.rst

@@ -55,7 +55,7 @@ conf
 
 ``cmake_layout`` is affected by these ``[conf]`` variables:
 
-- **tools.cmake.cmake_layout:build_folder_vars** list of settings, options and/or ``self.name`` and ``self.version`` to
+- **tools.cmake.cmake_layout:build_folder_vars** list of settings, options, ``self.name`` and ``self.version`` and constants ``const.xxx`` to
   customize the ``conanfile.folders.build`` folder. See section :ref:`cmake_layout_multi_name` below.
 - **tools.cmake.cmake_layout:build_folder** (*new since Conan 2.2.0*)(*experimental*) uses its value as the base folder of the ``conanfile.folders.build``
   for local builds.
@@ -71,7 +71,7 @@ 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, options and/or ``self.name`` and ``self.version``:
+conf to declare a list of settings, options and/or ``self.name`` and ``self.version`` and user constants:
 
 .. code:: bash
 
@@ -100,6 +100,13 @@ The values assigned by the ``cmake_layout`` (installing the Release/shared confi
 
 
 So we can keep separated folders for any number of different configurations that we want to install.
+Recipe attributes like name and version and user constants can also be used:
+
+.. code:: bash
+
+    $ conan install . -c tools.cmake.cmake_layout:build_folder_vars="['const.myvalue, 'self.name']"
+
+And it will create folders like ``build/myvalue-pkgname``.
 
 The ``CMakePresets.json`` file generated at the :ref:`CMakeToolchain<conan_tools_cmaketoolchain>`
 generator, will also take this ``tools.cmake.cmake_layout:build_folder_vars`` config into account to generate different

reference/tools/cmake/cmaketoolchain.rst

@@ -95,9 +95,9 @@ translated from the current ``settings``:
         - By default, preset names will be `conan-xxxx`, but the "conan-" prefix can be
           customized with the `CMakeToolchain.presets_prefix = "conan"` attribute.
         - Preset names are controlled by the `layout()` `self.folders.build_folder_vars`
-          definition, which can contain a list of settings, options and/or
-          ``self.name`` and ``self.version`` like
-          `["settings.compiler", "settings.arch", "options.shared"]`.
+          definition, which can contain a list of settings, options,
+          ``self.name`` and ``self.version`` and constants ``const.xxx`` like
+          `["settings.compiler", "settings.arch", "options.shared", "const.myname"]`.
         - If CMake is found as a direct `tool_requires` dependency, or if
           `tools.cmake:cmake_program` is set, the configure preset will include a
           `cmakeExecutable` field. This field represents the path to the CMake executable
@@ -752,7 +752,7 @@ This block injects ``$`` which will be expanded later. It also defines a cache v
 
 - **tools.cmake.cmaketoolchain:toolset_arch**: Will add the ``,host=xxx`` specifier in the ``CMAKE_GENERATOR_TOOLSET`` variable of ``conan_toolchain.cmake`` file.
 - **tools.cmake.cmaketoolchain:toolset_cuda**: (Experimental) Will add the ``,cuda=xxx`` specifier in the ``CMAKE_GENERATOR_TOOLSET`` variable of ``conan_toolchain.cmake`` file.
-- **tools.cmake.cmake_layout:build_folder_vars**: Settings, Options, and/or ``self.name`` and ``self.version`` that will produce a different build folder and different CMake presets names.
+- **tools.cmake.cmake_layout:build_folder_vars**: Settings, Options, ``self.name`` and ``self.version`` and constants ``const.uservalue`` that will produce a different build folder and different CMake presets names.
 - **tools.cmake.cmaketoolchain:presets_environment**: Set to ``'disabled'`` to prevent the addition of the environment section to the generated CMake presets.
 - **tools.build:cxxflags** list of extra C++ flags that will be appended to ``CMAKE_CXX_FLAGS_INIT``.
 - **tools.build:cflags** list of extra of pure C flags that will be appended to ``CMAKE_C_FLAGS_INIT``.