Help: Organize and revise 3.21 release notes

Add section headers similar to the 3.20 release notes and move each
individual bullet into an appropriate section.  Revise a few bullets.

1 files changed, 204 insertions, 148 deletions

diff --git a/Help/release/3.21.rst b/Help/release/3.21.rst
index 609ffb5..04354db 100644
--- a/Help/release/3.21.rst
+++ b/Help/release/3.21.rst
@@ -7,100 +7,104 @@ CMake 3.21 Release Notes
 
 Changes made since CMake 3.20 include the following.
 
-* The :command:`add_custom_command` command ``DEPFILE`` option learned to
-  support :manual:`generator expressions <cmake-generator-expressions(7)>`.
+New Features
+============
 
-* The :command:`add_custom_command` command gained ``DEPFILE`` support on
-  the :generator:`Xcode` generator, and on :ref:`Visual Studio Generators`
-  for VS 2012 and above.
+Presets
+-------
 
-* The :ref:`add_custom_command(TARGET) <add_custom_command(TARGET)>` command
-  gained support for resolving target-dependent generator expressions.
+* :manual:`cmake-presets(7)` gained support for specifying the install prefix
+  in a configure preset.
 
-* ``ARMClang`` cpu/arch compile and link flags are no longer added
-  automatically based on the :variable:`CMAKE_SYSTEM_PROCESSOR`
-  variable or the undocumented ``CMAKE_SYSTEM_ARCH`` variable.
-  They must be specified explicitly.  See policy :policy:`CMP0123`.
-
-* The :manual:`cmake(1)` ``-E capabilities`` output now contains for each
-  generator a ``supportedPlatforms`` field listing platform known to
-  be supported in :variable:`CMAKE_GENERATOR_PLATFORM`.
+* :manual:`cmake-presets(7)` gained support for conditional enabling of presets.
 
-* The :manual:`cmake(1)` command gained the ``--install-prefix <dir>``
-  command line option to specify the location of the install prefix.
+* :manual:`cmake-presets(7)` gained support for a ``${hostSystemName}`` macro.
 
-* :manual:`cmake-presets(7)` configure preset gained support for specifying
-  the install prefix.
+* :manual:`cmake-presets(7)` gained support for omitting the ``generator`` and
+  ``binaryDir`` fields.
 
-* :manual:`cmake-presets(7)` now support conditional enabling of presets.
+Generators
+----------
 
-* :manual:`cmake-presets(7)` gained support for a new ``${hostSystemName}``
-  macro.
+* The :ref:`Makefile Generators` and the :generator:`Ninja` generator
+  learned to add linker launcher tools along with the linker for ``C``,
+  ``CXX``, ``OBJC``, and ``OBJCXX`` languages.
+  See the :variable:`CMAKE_<LANG>_LINKER_LAUNCHER` variable
+  and :prop_tgt:`<LANG>_LINKER_LAUNCHER` target property for details.
 
-* :manual:`cmake-presets(7)` now support omitting the ``generator`` and
-  ``binaryDir`` fields.
+Languages
+---------
 
-* :variable:`CMAKE_HOST_SYSTEM_NAME`'s undocumented version-stripping behavior
-  has been moved earlier, before :command:`project` or
-  :command:`enable_language` is called.
-* :variable:`CMAKE_SYSTEM_NAME`'s undocumented version-stripping behavior has
-  been removed entirely. If it is set by a ``-D`` flag or by a
-  :manual:`toolchain file <cmake-toolchains(7)>`, it is left unaltered, even if
-  it still contains a version number.
+* CMake learned to support ``HIP`` as a first-class language that can be
+  enabled via the :command:`project` and :command:`enable_language` commands.
 
-* The :manual:`cmake(1)` command gained the ``--toolchain <path/to/file>``
-  command line option to specify a toolchain file.
+* :prop_tgt:`C_STANDARD`, :prop_tgt:`OBJC_STANDARD`, and the
+  :manual:`Compile Features <cmake-compile-features(7)>` functionality gained
+  support for C17 and C23.
 
-* The :ref:`Visual Studio Generators` for VS 2010 and above now place
-  per-source preprocessor definitions after target-wide preprocssor
-  definitions.  This makes VS consistent with the :ref:`Ninja Generators`
-  and the :ref:`Makefile Generators`.
+* Source file extensions ``.ixx`` and ``.cppm`` are now treated as C++.
 
-* The :cpack_gen:`CPack DragNDrop Generator` gained option
-  :variable:`CPACK_DMG_FILESYSTEM` to control the ``.dmg`` filesystem.
+Command-Line
+------------
 
-* The new :variable:`CPACK_CUSTOM_INSTALL_VARIABLES`
-  can be used to set variables in CPack ``cmake_install.cmake``
-  invocations.
+* :manual:`cmake(1)` gained the ``--install-prefix <dir>``
+  command-line option to specify the location of the install prefix.
 
-* The :cpack_gen:`CPack NSIS Generator` gained a new variable
-  :variable:`CPACK_NSIS_EXECUTABLE` to specify the makensis
-  executable to use instead of the default one.
+* :manual:`cmake(1)` gained the ``--toolchain <path/to/file>``
+  command-line option to specify a toolchain file.
 
-* :prop_tgt:`C_STANDARD` and the
-  :manual:`Compile Features <cmake-compile-features(7)>` functionality gained
-  support for C17 and C23.
+* :manual:`cmake(1)` ``-E capabilities`` output now contains for each
+  generator a ``supportedPlatforms`` field listing platforms known to
+  be supported in :variable:`CMAKE_GENERATOR_PLATFORM`.
 
-* :manual:`ctest(1)` gained documentation for its ability to capture
-  :ref:`Additional Test Measurements`.
+* Messages printed to a terminal now may be colored by message type.
 
-* :manual:`ctest(1)` gained a ``--output-junit`` option to write test results
-  to a JUnit XML file.
+Compilers
+---------
 
-* :manual:`ctest(1)` learned to recognize files attached to a test at run time.
-  Previously it was only possible to attach files to tests at configure time
-  by using the :prop_test:`ATTACHED_FILES` or
-  :prop_test:`ATTACHED_FILES_ON_FAIL` test properties.
-  See :ref:`Additional Test Measurements` for more information.
+* The Fujitsu compiler is now supported using compiler id ``Fujitsu``
+  in traditional (``Trad``) mode, and compiler id ``FujitsuClang``
+  in ``Clang`` mode.
 
-* Source file extensions ``.ixx`` and ``.cppm`` are now treated as C++.
+Platforms
+---------
 
-* The :prop_dir:`IMPORTED_TARGETS` directory property was added to
-  get a list of :ref:`Imported Targets` created in the current
-  directory.
+* CMake now supports the MSYS runtime environment, much like CYGWIN.
 
-* The :envvar:`CMAKE_TOOLCHAIN_FILE` environment variable was added to
-  provide a default value for the :variable:`CMAKE_TOOLCHAIN_FILE` variable.
+File-Based API
+--------------
 
-* The :manual:`cmake-file-api(7)` "codemodel" version 2 ``version`` field has
-  component been updated to 2.3.
+* The :manual:`cmake-file-api(7)` "codemodel" version 2 ``version`` field
+  has been updated to 2.3.
 
 * The :manual:`cmake-file-api(7)` "codemodel" version 2 gained a
   new "directory" object containing directory-level information.
   This includes a list of installers generated by the :command:`install`
   command.
 
-* The :command:`file(COPY_FILE)` command was added to copy a file to another.
+Commands
+--------
+
+* The :command:`add_custom_command` command ``DEPFILE`` option:
+
+  * may now use
+    :manual:`generator expressions <cmake-generator-expressions(7)>`,
+
+  * is now supported by :ref:`Visual Studio Generators` for VS 2012
+    and above, and
+
+  * is now supported by the :generator:`Xcode` generator.
+
+* The :command:`add_custom_command(TARGET)` command
+  (for :ref:`Build Events <add_custom_command(TARGET)>`)
+  gained support for resolving target-dependent generator expressions.
+
+* The :command:`build_command` command gained a ``PARALLEL_LEVEL`` option.
+
+* The :command:`file(COPY_FILE)` command was added to copy a single file.
+
+* The :command:`file(GET_RUNTIME_DEPENDENCIES)` command gained new
+  ``POST_INCLUDE_FILES`` and ``POST_EXCLUDE_FILES`` arguments.
 
 * The :command:`file(REAL_PATH)` command gained the option ``EXPAND_TILDE`` to
   replace any leading tilde with the path to the user's home directory.
@@ -109,93 +113,165 @@ Changes made since CMake 3.20 include the following.
   failure in a result variable.  It also gained a ``NO_REPLACE``
   option to fail if the destination exists.
 
+* The :command:`install` command gained a new ``IMPORTED_RUNTIME_ARTIFACTS``
+  mode, which can be used to install the runtime artifacts of imported targets.
+
+* The :command:`install` command gained a new ``RUNTIME_DEPENDENCY_SET`` mode,
+  which can be used to install runtime dependencies using
+  :command:`file(GET_RUNTIME_DEPENDENCIES)`.
+
+* The :command:`install(TARGETS)` command gained new ``RUNTIME_DEPENDENCIES``
+  and ``RUNTIME_DEPENDENCY_SET`` arguments, which can be used to install
+  runtime dependencies using :command:`file(GET_RUNTIME_DEPENDENCIES)`.
+
+* The :command:`install(SCRIPT|CODE)` command
+  supports a new option ``ALL_COMPONENTS`` which allows
+  the corresponding code to run for every component of
+  a per component installation.
+
+* The :command:`project` command now sets variables
+  :variable:`PROJECT_IS_TOP_LEVEL` and :variable:`<PROJECT-NAME>_IS_TOP_LEVEL`
+  to indicate whether it was called in a top-level ``CMakeLists.txt`` file.
+
+Variables
+---------
+
+* The :envvar:`CMAKE_TOOLCHAIN_FILE` environment variable was added to
+  provide a default value for the :variable:`CMAKE_TOOLCHAIN_FILE` variable.
+
+Properties
+----------
+
+* The :prop_dir:`IMPORTED_TARGETS` directory property was added to
+  get a list of :ref:`Imported Targets` created in the current
+  directory.
+
+* The :prop_tgt:`XCODE_EMBED_APP_EXTENSIONS <XCODE_EMBED_<type>>` target property
+  was added to tell the :generator:`Xcode` generator to embed app extensions
+  such as iMessage sticker packs.
+  Aspects of the embedding can be customized with the
+  :prop_tgt:`XCODE_EMBED_APP_EXTENSIONS_PATH <XCODE_EMBED_<type>>`,
+  :prop_tgt:`XCODE_EMBED_APP_EXTENSIONS_CODE_SIGN_ON_COPY <XCODE_EMBED_<type>_CODE_SIGN_ON_COPY>` and
+  :prop_tgt:`XCODE_EMBED_APP_EXTENSIONS_REMOVE_HEADERS_ON_COPY <XCODE_EMBED_<type>_REMOVE_HEADERS_ON_COPY>`
+  properties.
+
+Modules
+-------
+
+* The :module:`FindBLAS` and :module:`FindLAPACK` modules learned to support
+  the serial ``Fujitsu_SSL2`` and parallel ``Fujitsu_SSL2BLAMP`` libraries.
+
 * The :module:`FindDevIL` module now provides imported targets.
 
 * The :module:`FindIconv` module now has version support.
 
 * The :module:`FindIntl` module now has version support.
 
-* The :command:`find_file`, :command:`find_path`, :command:`find_program`,
-  and :command:`find_library` commands handle cache variables in the same way
-  regardless how they are defined. See policy :policy:`CMP0125` for details.
-
-* The :command:`find_file`, :command:`find_path`, :command:`find_program`,
-  and :command:`find_library` commands gained the option ``NO_CACHE`` to store
-  find result in normal variable.
+* The :module:`FindMPI` module learned to support ``Fujitsu`` and
+  ``FujitsuClang`` in both host and cross compiling modes.
 
 * The :module:`FindMsys` module was added to find MSYS installations.
   Like :module:`FindCygwin`, it is used automatically by some other
   find modules to locate UNIX-style tools on Windows.
 
+* The :module:`FindOpenMP` module learned to support ``Fujitsu`` and
+  ``FujitsuClang``.
+
 * The :module:`FindVulkan` module gained imported targets
   ``Vulkan::Headers`` and ``Vulkan::glslangValidator``.
 
-* The :command:`foreach` command restrict loop variables to the loop scope.
-  See policy :policy:`CMP0124` for details.
+* The :module:`UseJava` module command ``add_jar`` gained a ``RESOURCES``
+  option to allow explicit naming of resources with non-optional namespace.
 
-* Addition of the ``Fujitsu`` compiler ID operating in traditional ``Trad``
-  mode and ``FujitsuClang`` operating in ``Clang`` mode.
-* The :module:`FindOpenMP` module learned to support ``Fujitsu`` and
-  ``FujitsuClang``.
-* The :module:`FindMPI` module learned to support ``Fujitsu`` and
-  ``FujitsuClang`` in both host and cross compiling modes.
-* The :module:`FindBLAS` and :module:`FindLAPACK` modules learned to support
-  the serial ``Fujitsu SSL2`` and parallel ``Fujitsu SSL2BLAMP`` libraries.
+* The :module:`UseSWIG` module use now standard library naming conventions
+  for the ``CSharp`` language. See policy :policy:`CMP0122`.
 
-* The :command:`build_command` command gained a ``PARALLEL_LEVEL`` option.
+* The :module:`UseSWIG` module now supports using the ``swig`` tool to
+  generate implicit dependencies with the :generator:`Xcode` generator.
+
+Generator Expressions
+---------------------
+
+* A new :genex:`TARGET_RUNTIME_DLLS` generator expression was added.
+
+CTest
+-----
+
+* :manual:`ctest(1)` gained documentation for its ability to capture
+  :ref:`Additional Test Measurements`.
+
+* :manual:`ctest(1)` learned to recognize files attached to a test at run time.
+  Previously it was only possible to attach files to tests at configure time
+  by using the :prop_test:`ATTACHED_FILES` or
+  :prop_test:`ATTACHED_FILES_ON_FAIL` test properties.
+  See :ref:`Additional Test Measurements` for more information.
+
+* :manual:`ctest(1)` gained a ``--output-junit`` option to write test results
+  to a JUnit XML file.
 
 * The :command:`ctest_build` command gained a ``PARALLEL_LEVEL`` option.
 
-* The :command:`file(GET_RUNTIME_DEPENDENCIES)` command gained new
-  ``POST_INCLUDE_FILES`` and ``POST_EXCLUDE_FILES`` arguments.
+CPack
+-----
 
-* CMake learned to support ``HIP`` as a first-class language that can be
-  enabled via the :command:`project` and :command:`enable_language` commands.
+* The :cpack_gen:`CPack DragNDrop Generator` gained option
+  :variable:`CPACK_DMG_FILESYSTEM` to control the ``.dmg`` filesystem.
 
-* Names given as ``DEPENDS`` or ``DEPENDENCIES`` arguments to
-  :command:`cpack_ifw_configure_component` or
-  :command:`cpack_ifw_configure_component_group` may now contain hyphens.
-  This requires QtIFW 3.1 or later.
+* The :cpack_gen:`CPack IFW Generator` now supports hyphens in names
+  given to :command:`cpack_ifw_configure_component` or
+  :command:`cpack_ifw_configure_component_group` as ``DEPENDS`` or
+  ``DEPENDENCIES`` arguments.  This requires QtIFW 3.1 or later.
 
-* The :command:`install` command gained a new ``IMPORTED_RUNTIME_ARTIFACTS``
-  mode, which can be used to install the runtime artifacts of imported targets.
+* The :cpack_gen:`CPack NSIS Generator` gained a new
+  :variable:`CPACK_NSIS_EXECUTABLE` variable to specify the ``makensis``
+  executable to use instead of the default one.
 
-* The :command:`install(TARGETS)` command gained new ``RUNTIME_DEPENDENCIES``
-  and ``RUNTIME_DEPENDENCY_SET`` arguments, which can be used to install
-  runtime dependencies using :command:`file(GET_RUNTIME_DEPENDENCIES)`.
-* The :command:`install` command gained a new ``RUNTIME_DEPENDENCY_SET`` mode,
-  which can be used to install runtime dependencies using
-  :command:`file(GET_RUNTIME_DEPENDENCIES)`.
+* The :variable:`CPACK_CUSTOM_INSTALL_VARIABLES` variable was added to set
+  variables in ``cmake_install.cmake`` script invocations made by CPack.
 
-* The :command:`install(SCRIPT|CODE)` command
-  supports a new option ``ALL_COMPONENTS`` which allows
-  the corresponding code to run for every component of
-  a per component installation.
+Deprecated and Removed Features
+===============================
 
-* The :ref:`Makefile Generators` and the :generator:`Ninja` generator learned to
-  add linker launcher tools along with the linker for ``C``, ``CXX``, ``OBJC``, and
-  ``OBJCXX`` languages. See the :variable:`CMAKE_<LANG>_LINKER_LAUNCHER` variable
-  and :prop_tgt:`<LANG>_LINKER_LAUNCHER` target property for details.
+* Undocumented :variable:`CMAKE_SYSTEM_NAME` version-stripping behavior has
+  been removed entirely. If it is set by a ``-D`` flag or by a
+  :manual:`toolchain file <cmake-toolchains(7)>`, it is left unaltered,
+  even if it still contains a version number.
+  Similar :variable:`CMAKE_HOST_SYSTEM_NAME` version-stripping behavior,
+  also undocumented, has been moved earlier, before :command:`project` or
+  :command:`enable_language` is called.
 
-* :command:`target_link_libraries` calls referencing object libraries
-  via the :genex:`TARGET_OBJECTS` generator expression now place the
-  object files before all libraries on the link line, regardless of
-  their specified order.  See documentation on
-  :ref:`Linking Object Libraries via \$\<TARGET_OBJECTS\>` for details.
+* ``ARMClang`` cpu/arch compile and link flags are no longer added
+  automatically based on the :variable:`CMAKE_SYSTEM_PROCESSOR`
+  variable or the undocumented ``CMAKE_SYSTEM_ARCH`` variable.
+  They must be specified explicitly.  See policy :policy:`CMP0123`.
+
+Other Changes
+=============
+
+* The :command:`find_file`, :command:`find_path`, :command:`find_program`,
+  and :command:`find_library` commands handle cache variables in the same way
+  regardless how they are defined. See policy :policy:`CMP0125` for details.
+
+* The :command:`find_file`, :command:`find_path`, :command:`find_program`,
+  and :command:`find_library` commands gained the option ``NO_CACHE`` to store
+  find result in normal variable.
+
+* The :command:`foreach` command now isolates loop variables in the loop scope.
+  See policy :policy:`CMP0124` for details.
 
 * The :command:`list` command's ``GET``, ``INSERT``, ``SUBLIST``, and
   ``REMOVE_AT`` subcommands now error with invalid (i.e., non-integer) values
   are given as any of their index arguments based on the setting of policy
   :policy:`CMP0121`.
 
-* The precompiled binaries provided on
-  `cmake.org <https://cmake.org/download/>`_ now support
-  ``liblzma`` multi-threading.  See the :variable:`CPACK_THREADS` and
-  :variable:`CPACK_ARCHIVE_THREADS` variables.
+* The :command:`set(CACHE)` command no longer removes a normal variable
+  of the same name, if any. See policy :policy:`CMP0126`.
 
-* Messages printed to a terminal now may be colored by message type.
-
-* CMake now supports the MSYS runtime environment, much like CYGWIN.
+* :command:`target_link_libraries` calls referencing object libraries
+  via the :genex:`TARGET_OBJECTS` generator expression now place the
+  object files before all libraries on the link line, regardless of
+  their specified order.  See documentation on
+  :ref:`Linking Object Libraries via \$\<TARGET_OBJECTS\>` for details.
 
 * The :ref:`Ninja Generators` now pass source files and include directories
   to the compiler using absolute paths.  This makes diagnostic messages and
@@ -204,32 +280,12 @@ Changes made since CMake 3.20 include the following.
 * The :generator:`NMake Makefiles` generator now encodes the generated
   makefiles as UTF-8 with a BOM when using ``nmake`` from VS 9 or above.
 
-* :prop_tgt:`OBJC_STANDARD` gained support for C17 and C23.
-
-* :command:`project` now sets variables :variable:`PROJECT_IS_TOP_LEVEL` and
-  :variable:`<PROJECT-NAME>_IS_TOP_LEVEL` to indicate whether it was called
-  in a top level ``CMakeLists.txt`` file.
-
-* A new :genex:`TARGET_RUNTIME_DLLS` generator expression was added.
-
-* The :command:`set(CACHE)` command no longer removes a normal variable of the
-  same name, if any. See policy :policy:`CMP0126`.
-
-* The :module:`UseJava` module command ``add_jar`` gained option RESOURCES
-  allow explicit naming of resources with non-optional namespace.
-
-* The :module:`UseSWIG` module use now standard library name conventions for
-  ``CSharp`` language. See policy :policy:`CMP0122`.
-
-* :module:`UseSWIG` module gained the capability, for
-  :generator:`Xcode` generator, to use `swig` tool to generate implicit
-  dependencies.
+* The :ref:`Visual Studio Generators` for VS 2010 and above now place
+  per-source preprocessor definitions after target-wide preprocssor
+  definitions.  This makes VS consistent with the :ref:`Ninja Generators`
+  and the :ref:`Makefile Generators`.
 
-* The :prop_tgt:`XCODE_EMBED_APP_EXTENSIONS <XCODE_EMBED_<type>>` target property
-  was added to tell the :generator:`Xcode` generator to embed app extensions
-  such as iMessage sticker packs.
-  Aspects of the embedding can be customized with the
-  :prop_tgt:`XCODE_EMBED_APP_EXTENSIONS_PATH <XCODE_EMBED_<type>>`,
-  :prop_tgt:`XCODE_EMBED_APP_EXTENSIONS_CODE_SIGN_ON_COPY <XCODE_EMBED_<type>_CODE_SIGN_ON_COPY>` and
-  :prop_tgt:`XCODE_EMBED_APP_EXTENSIONS_REMOVE_HEADERS_ON_COPY <XCODE_EMBED_<type>_REMOVE_HEADERS_ON_COPY>`
-  properties.
+* The precompiled binaries provided on
+  `cmake.org <https://cmake.org/download/>`_ now support
+  ``liblzma`` multi-threading.  See the :variable:`CPACK_THREADS` and
+  :variable:`CPACK_ARCHIVE_THREADS` variables.