Help/release/3.12.rst - third_party/cmake - Git at Google

 CMake 3.12 Release Notes
 ************************

 .. only:: html

   .. contents::

 Changes made since CMake 3.11 include the following.

 New Features
 ============

 Generators
 ----------

 * The :ref:`Visual Studio Generators` for VS 2017 learned to support a
   ``version=14.##`` option in the :variable:`CMAKE_GENERATOR_TOOLSET`
   value (e.g. via the :manual:`cmake(1)` ``-T`` option) to specify a
   toolset version number.

 Command-Line
 ------------

 * The :manual:`cmake(1)` :ref:`Build Tool Mode` (``cmake --build``) gained
   ``--parallel [<jobs>]`` and ``-j [<jobs>]`` options to specify a parallel
   build level.  They map to corresponding options of the native build tool.

 Commands
 --------

 * The :command:`add_compile_definitions` command was added to set preprocessor
   definitions at directory level.  This supersedes :command:`add_definitions`.

 * The :command:`cmake_minimum_required` and :command:`cmake_policy(VERSION)`
   commands now accept a version range using the form ``<min>[...<max>]``.
   The ``<min>`` version is required but policies are set based on the
   older of the running CMake version and the version specified by
   ``<max>``.  This allows projects to specify a range of versions
   for which they have been updated and avoid explicit policy settings.

 * The :command:`file(GLOB)` and :command:`file(GLOB_RECURSE)` commands
   learned a new flag ``CONFIGURE_DEPENDS`` which enables expression of
   build system dependency on globbed directory's contents.

 * The :command:`file(TOUCH)` and :command:`file(TOUCH_NOCREATE)` commands
   were added to expose ``TOUCH`` functionality without having to use
   CMake's command-line tool mode with :command:`execute_process`.

 * The :command:`find_package` command now searches prefixes specified by
   the :variable:`<PackageName>_ROOT` CMake variable and the
   :envvar:`<PackageName>_ROOT` environment variable.  Package roots are
   maintained as a stack so nested calls to all ``find_*`` commands inside
   find modules also search the roots as prefixes.
   See policy :policy:`CMP0074`.

 * The :command:`install` command learned an optional ``NAMELINK_COMPONENT``
   parameter, which allows you to change the component for a shared library's
   namelink. If none is specified, the value of ``COMPONENT`` is used by
   default.

 * The :command:`list` command learned a ``JOIN`` sub-command
   to concatenate list's elements separated by a glue string.

 * The :command:`list` command learned a ``SUBLIST`` sub-command
   to get a sublist of the list.

 * The :command:`list` command learned a ``TRANSFORM`` sub-command
   to apply various string transformation to list's elements.

 * The :command:`project` command learned an optional ``HOMEPAGE_URL``
   parameter which has the effect of setting variables like
   :variable:`PROJECT_HOMEPAGE_URL`, :variable:`<PROJECT-NAME>_HOMEPAGE_URL`
   and :variable:`CMAKE_PROJECT_HOMEPAGE_URL`.

 * The :command:`string` command learned a ``JOIN`` sub-command
   to concatenate input strings separated by a glue string.

 * :command:`target_compile_options` and :command:`add_compile_options`
   commands gained a ``SHELL:`` prefix to specify a group of related
   options using shell-like quoting.

 * The :command:`target_link_libraries` command now supports
   :ref:`Object Libraries`.  Linking to an object library uses its object
   files in direct dependents and also propagates usage requirements.

 Variables
 ---------

 * The :variable:`CMAKE_FOLDER` variable was added to initialize the
   :prop_tgt:`FOLDER` property on all targets.

 * The :variable:`CMAKE_DOTNET_TARGET_FRAMEWORK_VERSION` variable
   was defined to initialize all
   :prop_tgt:`DOTNET_TARGET_FRAMEWORK_VERSION` target properties.

 * ``CMAKE_PROJECT_VERSION*`` variables have been introduced:

   - :variable:`CMAKE_PROJECT_VERSION`
   - :variable:`CMAKE_PROJECT_VERSION_MAJOR`
   - :variable:`CMAKE_PROJECT_VERSION_MINOR`
   - :variable:`CMAKE_PROJECT_VERSION_PATCH`
   - :variable:`CMAKE_PROJECT_VERSION_TWEAK`

 * The :variable:`CMAKE_SUPPRESS_REGENERATION` variable was extended to
   support the :generator:`Ninja` and :ref:`Makefile Generators`.
   It is also now documented.

 * ``CMAKE_VS_SDK_*_DIRECTORIES`` variables were defined to tell
   :ref:`Visual Studio Generators` for VS 2010 and above how to populate
   fields in ``.vcxproj`` files that specify SDK directories.  The
   variables are:

   - :variable:`CMAKE_VS_SDK_EXCLUDE_DIRECTORIES`
   - :variable:`CMAKE_VS_SDK_EXECUTABLE_DIRECTORIES`
   - :variable:`CMAKE_VS_SDK_INCLUDE_DIRECTORIES`
   - :variable:`CMAKE_VS_SDK_LIBRARY_DIRECTORIES`
   - :variable:`CMAKE_VS_SDK_LIBRARY_WINRT_DIRECTORIES`
   - :variable:`CMAKE_VS_SDK_REFERENCE_DIRECTORIES`
   - :variable:`CMAKE_VS_SDK_SOURCE_DIRECTORIES`

 * A :variable:`MSVC_TOOLSET_VERSION` variable was added to provide the
   MSVC toolset version associated with the current MSVC compiler version
   in :variable:`MSVC_VERSION`.

 Properties
 ----------

 * The :prop_tgt:`COMMON_LANGUAGE_RUNTIME` target property was introduced
   to configure the use of managed C++ for :ref:`Visual Studio Generators`
   for VS 2010 and above.
   A corresponding :prop_tgt:`IMPORTED_COMMON_LANGUAGE_RUNTIME` target
   property was added to support ``C++/CLI`` for imported targets.

 * The :prop_tgt:`DOTNET_TARGET_FRAMEWORK_VERSION` target property
   was introduced as replacement for
   :prop_tgt:`VS_DOTNET_TARGET_FRAMEWORK_VERSION`, which is considered
   deprecated now.

 * An :prop_tgt:`EXPORT_PROPERTIES` target property was added to specify a
   custom list of target properties to include in targets exported by the
   :command:`install(EXPORT)` and :command:`export` commands.

 * The :prop_tgt:`PDB_OUTPUT_DIRECTORY` property learned to support
   :manual:`generator expressions <cmake-generator-expressions(7)>`.

 * A :prop_dir:`TESTS` directory property was added to hold the list of
   tests defined by the :command:`add_test` command.

 * A :prop_tgt:`VS_DEBUGGER_COMMAND` target property was created to set the
   debugging command line with :ref:`Visual Studio Generators` for VS 2010
   and above.

 * HLSL source file properties :prop_sf:`VS_SHADER_DISABLE_OPTIMIZATIONS`
   and :prop_sf:`VS_SHADER_ENABLE_DEBUG` gained support for generator
   expressions.

 * HLSL source file property :prop_sf:`VS_SHADER_OBJECT_FILE_NAME` has been
   added to the :ref:`Visual Studio Generators` for VS 2010 and above.
   The property specifies the file name of the compiled shader object.

 Modules
 -------

 * The :module:`FindALSA` module now provides imported targets.

 * The :module:`FindCURL` module now provides imported targets.

 * The :module:`FindJPEG` module now provides imported targets.

 * The :module:`FindLibXml2` module now provides imported targets.

 * The :module:`FindMatlab` module now supports the Matlab Runtime
   Compiler (MCR) for compiling and linking matlab extensions.

 * A :module:`FindODBC` module was added to find an Open Database Connectivity
   (ODBC) library.

 * The :module:`FindPkgConfig` module has learned to export the found
   libraries with full path for direct consumption with the
   :command:`target_link_libraries` command.

 * New :module:`FindPython3` and :module:`FindPython2` modules, as well as
   a new :module:`FindPython` module, have been added to provide a new way
   to locate python environments.

 * The :module:`UseSWIG` module gained a whole refresh and is now more
   consistent with standard CMake commands to generate libraries and is
   fully configurable through properties.

 * The :module:`UseSWIG` module learned to manage multiple behaviors through
   ``UseSWIG_MODULE_VERSION`` variable to ensure legacy support as well as more
   robust handling of ``SWIG`` advanced features (like ``%template``).

 * The :module:`UseSWIG` module learned to support CSHARP variant
   wrapper files.

 * The :module:`WriteCompilerDetectionHeader` module gained a ``BARE_FEATURES``
   option to add a compatibility define for the exact keyword of a new language
   feature.

 Generator Expressions
 ---------------------

 * A new ``$<GENEX_EVAL:...>`` and ``$<TARGET_GENEX_EVAL:target,...>``
   :manual:`generator expression <cmake-generator-expressions(7)>`
   has been added to enable consumption of generator expressions whose
   evaluation results itself in generator expressions.

 * A new ``$<IN_LIST:...>``
   :manual:`generator expression <cmake-generator-expressions(7)>`
   has been added.

 * A new ``$<TARGET_EXISTS:...>``
   :manual:`generator expression <cmake-generator-expressions(7)>`
   has been added.

 * A new ``$<TARGET_NAME_IF_EXISTS:...>``
   :manual:`generator expression <cmake-generator-expressions(7)>`
   has been added.

 CTest
 -----

 * The :command:`ctest_start` command has been reworked so that you can simply
   call ``ctest_start(APPEND)`` and it will read all the needed information from
   the TAG file. The argument parsing has also been relaxed so that the order of
   the arguments is less significant.

 * A :prop_test:`PROCESSOR_AFFINITY` test property was added to request
   that CTest run a test with CPU affinity for a set of processors
   disjoint from other concurrently running tests with the property set.

 CPack
 -----

 * The :module:`CPack` module now uses variables
   :variable:`CMAKE_PROJECT_VERSION_MAJOR`,
   :variable:`CMAKE_PROJECT_VERSION_MINOR` and
   :variable:`CMAKE_PROJECT_VERSION_PATCH`
   to initialize corresponding CPack variables.

 * A :cpack_gen:`CPack NuGet Generator` was was added with basic
   support for `NuGet`_.

 .. _NuGet: https://docs.microsoft.com/en-us/nuget/what-is-nuget

 Other
 -----

 * The :manual:`Compile Features <cmake-compile-features(7)>` functionality
   is now aware of C++ 20.  No specific features are yet enumerated besides
   the ``cxx_std_20`` meta-feature.

 * The :manual:`Compile Features <cmake-compile-features(7)>` functionality
   is now aware of the availability of C features in MSVC since VS 2010.

 * The :manual:`Compile Features <cmake-compile-features(7)>` functionality
   is now aware of C language standards supported by Texas Instruments C
   compilers.

 Deprecated and Removed Features
 ===============================

 * The :generator:`Visual Studio 8 2005` generator has been removed.

 * CMake no longer produces ``<tgt>_LIB_DEPENDS`` cache entries
   for library targets.  See policy :policy:`CMP0073`.

 Other Changes
 =============

 * Include flags for directories marked as ``SYSTEM`` are now moved after
   non-system directories.  The ``-isystem`` flag does this automatically,
   so moving them explicitly to the end makes the behavior consistent on
   compilers that do not have any ``-isystem`` flag.

 * Fortran dependency scanning now supports dependencies implied by
   `Fortran Submodules`_.

 * The existence and functionality of the file
   ``${CMAKE_BINARY_DIR}/cmake_install.cmake`` has now been documented in the
   :command:`install` documentation so that external packaging software can take
   advantage of CPack-style component installs.

 * The :module:`CheckIncludeFile` module ``check_include_file`` macro
   learned to honor the ``CMAKE_REQUIRED_LIBRARIES`` variable.
   See policy :policy:`CMP0075`.

 * The :module:`CheckIncludeFileCXX` module ``check_include_file_cxx`` macro
   learned to honor the ``CMAKE_REQUIRED_LIBRARIES`` variable.
   See policy :policy:`CMP0075`.

 * The :module:`CheckIncludeFiles` module ``check_include_files`` macro
   learned to honor the ``CMAKE_REQUIRED_LIBRARIES`` variable.
   See policy :policy:`CMP0075`.

 * The :manual:`cmake(1)` ``-E copy_directory`` tool now fails when the
   source directory does not exist.  Previously it succeeded by creating
   an empty destination directory.

 * The :module:`UseSWIG` module :command:`swig_add_library` command
   (and legacy ``swig_add_module`` command) now set the prefix of
   Java modules to ``""`` for MINGW, MSYS, and CYGWIN environments.

 .. _`Fortran Submodules`: http://fortranwiki.org/fortran/show/Submodules
	CMake 3.12 Release Notes
	************************

	.. only:: html

	.. contents::

	Changes made since CMake 3.11 include the following.

	New Features
	============

	Generators
	----------

	* The :ref:`Visual Studio Generators` for VS 2017 learned to support a
	``version=14.##`` option in the :variable:`CMAKE_GENERATOR_TOOLSET`
	value (e.g. via the :manual:`cmake(1)` ``-T`` option) to specify a
	toolset version number.

	Command-Line
	------------

	* The :manual:`cmake(1)` :ref:`Build Tool Mode` (``cmake --build``) gained
	``--parallel [<jobs>]`` and ``-j [<jobs>]`` options to specify a parallel
	build level. They map to corresponding options of the native build tool.

	Commands
	--------

	* The :command:`add_compile_definitions` command was added to set preprocessor
	definitions at directory level. This supersedes :command:`add_definitions`.

	* The :command:`cmake_minimum_required` and :command:`cmake_policy(VERSION)`
	commands now accept a version range using the form ``<min>[...<max>]``.
	The ``<min>`` version is required but policies are set based on the
	older of the running CMake version and the version specified by
	``<max>``. This allows projects to specify a range of versions
	for which they have been updated and avoid explicit policy settings.

	* The :command:`file(GLOB)` and :command:`file(GLOB_RECURSE)` commands
	learned a new flag ``CONFIGURE_DEPENDS`` which enables expression of
	build system dependency on globbed directory's contents.

	* The :command:`file(TOUCH)` and :command:`file(TOUCH_NOCREATE)` commands
	were added to expose ``TOUCH`` functionality without having to use
	CMake's command-line tool mode with :command:`execute_process`.

	* The :command:`find_package` command now searches prefixes specified by
	the :variable:`<PackageName>_ROOT` CMake variable and the
	:envvar:`<PackageName>_ROOT` environment variable. Package roots are
	maintained as a stack so nested calls to all ``find_*`` commands inside
	find modules also search the roots as prefixes.
	See policy :policy:`CMP0074`.

	* The :command:`install` command learned an optional ``NAMELINK_COMPONENT``
	parameter, which allows you to change the component for a shared library's
	namelink. If none is specified, the value of ``COMPONENT`` is used by
	default.

	* The :command:`list` command learned a ``JOIN`` sub-command
	to concatenate list's elements separated by a glue string.

	* The :command:`list` command learned a ``SUBLIST`` sub-command
	to get a sublist of the list.

	* The :command:`list` command learned a ``TRANSFORM`` sub-command
	to apply various string transformation to list's elements.

	* The :command:`project` command learned an optional ``HOMEPAGE_URL``
	parameter which has the effect of setting variables like
	:variable:`PROJECT_HOMEPAGE_URL`, :variable:`<PROJECT-NAME>_HOMEPAGE_URL`
	and :variable:`CMAKE_PROJECT_HOMEPAGE_URL`.

	* The :command:`string` command learned a ``JOIN`` sub-command
	to concatenate input strings separated by a glue string.

	* :command:`target_compile_options` and :command:`add_compile_options`
	commands gained a ``SHELL:`` prefix to specify a group of related
	options using shell-like quoting.

	* The :command:`target_link_libraries` command now supports
	:ref:`Object Libraries`. Linking to an object library uses its object
	files in direct dependents and also propagates usage requirements.

	Variables
	---------

	* The :variable:`CMAKE_FOLDER` variable was added to initialize the
	:prop_tgt:`FOLDER` property on all targets.

	* The :variable:`CMAKE_DOTNET_TARGET_FRAMEWORK_VERSION` variable
	was defined to initialize all
	:prop_tgt:`DOTNET_TARGET_FRAMEWORK_VERSION` target properties.

	* ``CMAKE_PROJECT_VERSION*`` variables have been introduced:

	- :variable:`CMAKE_PROJECT_VERSION`
	- :variable:`CMAKE_PROJECT_VERSION_MAJOR`
	- :variable:`CMAKE_PROJECT_VERSION_MINOR`
	- :variable:`CMAKE_PROJECT_VERSION_PATCH`
	- :variable:`CMAKE_PROJECT_VERSION_TWEAK`

	* The :variable:`CMAKE_SUPPRESS_REGENERATION` variable was extended to
	support the :generator:`Ninja` and :ref:`Makefile Generators`.
	It is also now documented.

	* ``CMAKE_VS_SDK_*_DIRECTORIES`` variables were defined to tell
	:ref:`Visual Studio Generators` for VS 2010 and above how to populate
	fields in ``.vcxproj`` files that specify SDK directories. The
	variables are:

	- :variable:`CMAKE_VS_SDK_EXCLUDE_DIRECTORIES`
	- :variable:`CMAKE_VS_SDK_EXECUTABLE_DIRECTORIES`
	- :variable:`CMAKE_VS_SDK_INCLUDE_DIRECTORIES`
	- :variable:`CMAKE_VS_SDK_LIBRARY_DIRECTORIES`
	- :variable:`CMAKE_VS_SDK_LIBRARY_WINRT_DIRECTORIES`
	- :variable:`CMAKE_VS_SDK_REFERENCE_DIRECTORIES`
	- :variable:`CMAKE_VS_SDK_SOURCE_DIRECTORIES`

	* A :variable:`MSVC_TOOLSET_VERSION` variable was added to provide the
	MSVC toolset version associated with the current MSVC compiler version
	in :variable:`MSVC_VERSION`.

	Properties
	----------

	* The :prop_tgt:`COMMON_LANGUAGE_RUNTIME` target property was introduced
	to configure the use of managed C++ for :ref:`Visual Studio Generators`
	for VS 2010 and above.
	A corresponding :prop_tgt:`IMPORTED_COMMON_LANGUAGE_RUNTIME` target
	property was added to support ``C++/CLI`` for imported targets.

	* The :prop_tgt:`DOTNET_TARGET_FRAMEWORK_VERSION` target property
	was introduced as replacement for
	:prop_tgt:`VS_DOTNET_TARGET_FRAMEWORK_VERSION`, which is considered
	deprecated now.

	* An :prop_tgt:`EXPORT_PROPERTIES` target property was added to specify a
	custom list of target properties to include in targets exported by the
	:command:`install(EXPORT)` and :command:`export` commands.

	* The :prop_tgt:`PDB_OUTPUT_DIRECTORY` property learned to support
	:manual:`generator expressions <cmake-generator-expressions(7)>`.

	* A :prop_dir:`TESTS` directory property was added to hold the list of
	tests defined by the :command:`add_test` command.

	* A :prop_tgt:`VS_DEBUGGER_COMMAND` target property was created to set the
	debugging command line with :ref:`Visual Studio Generators` for VS 2010
	and above.

	* HLSL source file properties :prop_sf:`VS_SHADER_DISABLE_OPTIMIZATIONS`
	and :prop_sf:`VS_SHADER_ENABLE_DEBUG` gained support for generator
	expressions.

	* HLSL source file property :prop_sf:`VS_SHADER_OBJECT_FILE_NAME` has been
	added to the :ref:`Visual Studio Generators` for VS 2010 and above.
	The property specifies the file name of the compiled shader object.

	Modules
	-------

	* The :module:`FindALSA` module now provides imported targets.

	* The :module:`FindCURL` module now provides imported targets.

	* The :module:`FindJPEG` module now provides imported targets.

	* The :module:`FindLibXml2` module now provides imported targets.

	* The :module:`FindMatlab` module now supports the Matlab Runtime
	Compiler (MCR) for compiling and linking matlab extensions.

	* A :module:`FindODBC` module was added to find an Open Database Connectivity
	(ODBC) library.

	* The :module:`FindPkgConfig` module has learned to export the found
	libraries with full path for direct consumption with the
	:command:`target_link_libraries` command.

	* New :module:`FindPython3` and :module:`FindPython2` modules, as well as
	a new :module:`FindPython` module, have been added to provide a new way
	to locate python environments.

	* The :module:`UseSWIG` module gained a whole refresh and is now more
	consistent with standard CMake commands to generate libraries and is
	fully configurable through properties.

	* The :module:`UseSWIG` module learned to manage multiple behaviors through
	``UseSWIG_MODULE_VERSION`` variable to ensure legacy support as well as more
	robust handling of ``SWIG`` advanced features (like ``%template``).

	* The :module:`UseSWIG` module learned to support CSHARP variant
	wrapper files.

	* The :module:`WriteCompilerDetectionHeader` module gained a ``BARE_FEATURES``
	option to add a compatibility define for the exact keyword of a new language
	feature.

	Generator Expressions
	---------------------

	* A new ``$<GENEX_EVAL:...>`` and ``$<TARGET_GENEX_EVAL:target,...>``
	:manual:`generator expression <cmake-generator-expressions(7)>`
	has been added to enable consumption of generator expressions whose
	evaluation results itself in generator expressions.

	* A new ``$<IN_LIST:...>``
	:manual:`generator expression <cmake-generator-expressions(7)>`
	has been added.

	* A new ``$<TARGET_EXISTS:...>``
	:manual:`generator expression <cmake-generator-expressions(7)>`
	has been added.

	* A new ``$<TARGET_NAME_IF_EXISTS:...>``
	:manual:`generator expression <cmake-generator-expressions(7)>`
	has been added.

	CTest
	-----

	* The :command:`ctest_start` command has been reworked so that you can simply
	call ``ctest_start(APPEND)`` and it will read all the needed information from
	the TAG file. The argument parsing has also been relaxed so that the order of
	the arguments is less significant.

	* A :prop_test:`PROCESSOR_AFFINITY` test property was added to request
	that CTest run a test with CPU affinity for a set of processors
	disjoint from other concurrently running tests with the property set.

	CPack
	-----

	* The :module:`CPack` module now uses variables
	:variable:`CMAKE_PROJECT_VERSION_MAJOR`,
	:variable:`CMAKE_PROJECT_VERSION_MINOR` and
	:variable:`CMAKE_PROJECT_VERSION_PATCH`
	to initialize corresponding CPack variables.

	* A :cpack_gen:`CPack NuGet Generator` was was added with basic
	support for `NuGet`_.

	.. _NuGet: https://docs.microsoft.com/en-us/nuget/what-is-nuget

	Other
	-----

	* The :manual:`Compile Features <cmake-compile-features(7)>` functionality
	is now aware of C++ 20. No specific features are yet enumerated besides
	the ``cxx_std_20`` meta-feature.

	* The :manual:`Compile Features <cmake-compile-features(7)>` functionality
	is now aware of the availability of C features in MSVC since VS 2010.

	* The :manual:`Compile Features <cmake-compile-features(7)>` functionality
	is now aware of C language standards supported by Texas Instruments C
	compilers.

	Deprecated and Removed Features
	===============================

	* The :generator:`Visual Studio 8 2005` generator has been removed.

	* CMake no longer produces ``<tgt>_LIB_DEPENDS`` cache entries
	for library targets. See policy :policy:`CMP0073`.

	Other Changes
	=============

	* Include flags for directories marked as ``SYSTEM`` are now moved after
	non-system directories. The ``-isystem`` flag does this automatically,
	so moving them explicitly to the end makes the behavior consistent on
	compilers that do not have any ``-isystem`` flag.

	* Fortran dependency scanning now supports dependencies implied by
	`Fortran Submodules`_.

	* The existence and functionality of the file
	``${CMAKE_BINARY_DIR}/cmake_install.cmake`` has now been documented in the
	:command:`install` documentation so that external packaging software can take
	advantage of CPack-style component installs.

	* The :module:`CheckIncludeFile` module ``check_include_file`` macro
	learned to honor the ``CMAKE_REQUIRED_LIBRARIES`` variable.
	See policy :policy:`CMP0075`.

	* The :module:`CheckIncludeFileCXX` module ``check_include_file_cxx`` macro
	learned to honor the ``CMAKE_REQUIRED_LIBRARIES`` variable.
	See policy :policy:`CMP0075`.

	* The :module:`CheckIncludeFiles` module ``check_include_files`` macro
	learned to honor the ``CMAKE_REQUIRED_LIBRARIES`` variable.
	See policy :policy:`CMP0075`.

	* The :manual:`cmake(1)` ``-E copy_directory`` tool now fails when the
	source directory does not exist. Previously it succeeded by creating
	an empty destination directory.

	* The :module:`UseSWIG` module :command:`swig_add_library` command
	(and legacy ``swig_add_module`` command) now set the prefix of
	Java modules to ``""`` for MINGW, MSYS, and CYGWIN environments.

	.. _`Fortran Submodules`: http://fortranwiki.org/fortran/show/Submodules