CMake 3.19 Release Notes
************************

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Changes made since CMake 3.18 include the following.

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

Presets
-------

* :manual:`cmake(1)` and :manual:`cmake-gui(1)` now recognize
  ``CMakePresets.json`` and ``CMakeUserPresets.json`` files.

Generators
----------

* The :generator:`Xcode` generator now uses the Xcode "new build system"
  when generating for Xcode 12.0 or higher.
  See the :variable:`CMAKE_XCODE_BUILD_SYSTEM` variable.
  One may use ``-T buildsystem=1`` to switch to the legacy build system.

* The :generator:`Xcode` generator gained support for linking libraries and
  frameworks via the *Link Binaries With Libraries* build phase instead of
  always by embedding linker flags directly.  This behavior is controlled by
  a new :prop_tgt:`XCODE_LINK_BUILD_PHASE_MODE` target property, which is
  initialized by a new :variable:`CMAKE_XCODE_LINK_BUILD_PHASE_MODE`
  variable.

* The :ref:`Visual Studio Generators` for VS 2015 and above gained support
  for the Visual Studio Tools for Android.  One may now set
  :variable:`CMAKE_SYSTEM_NAME` to ``Android`` to generate ``.vcxproj`` files
  for the Android tools.

Languages
---------

* CMake learned to support ``ISPC`` as a first-class language that can be
  enabled via the :command:`project` and :command:`enable_language` commands.
  ``ISPC`` is currently supported by the :ref:`Makefile Generators`
  and the :generator:`Ninja` generator on Linux, macOS, and Windows
  using the Intel ISPC compiler.

* ``CUDA`` language support for Clang now includes:

  - separable compilation (:prop_tgt:`CUDA_SEPARABLE_COMPILATION`), and
  - finding scattered toolkit installations when cross-compiling.

File-Based API
--------------

* The :manual:`cmake-file-api(7)` "codemodel" version 2 ``version`` field has
  been updated to 2.2.

* The :manual:`cmake-file-api(7)` "codemodel" version 2 "target" object
  gained a new ``languageStandard`` field in the ``compileGroups`` objects.

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

* The :manual:`cmake(1)` command-line tool's ``--install`` mode gained a
  ``--default-directory-permissions`` option.

* :manual:`cmake(1)` gained a ``-E create_hardlink`` command-line tool
  that can be used to create hardlinks between files.

GUI
---

* The :manual:`CMake GUI <cmake-gui(1)>` now has an environment variable
  editor.

Commands
--------

* The :command:`add_test` command now (officially) supports whitespace and
  other special characters in the name for the test it creates.
  See policy :policy:`CMP0110`.

* The :command:`cmake_language` command gained a ``DEFER`` mode to
  schedule command calls to occur at the end of processing a directory.

* The :command:`cmake_path` command was added for operations on
  filesystem paths.

* The :command:`configure_file` command gained a ``NO_SOURCE_PERMISSIONS``
  option to suppress copying the input file's permissions to the output file.

* The :command:`execute_process` command gained a ``COMMAND_ERROR_IS_FATAL``
  option to specify a fatal error.

* The :command:`file(ARCHIVE_CREATE)` command gained a ``COMPRESSION_LEVEL``
  option to specify the compression level.

* The :command:`file(CHMOD)` and :command:`file(CHMOD_RECURSE)` subcommands
  were added to set permissions of files and directories.

* The :command:`file(DOWNLOAD)` command ``<file>`` argument is now
  optional.  If it is not specified, the file is not saved.

* The :command:`file(GENERATE)` command gained a new ``TARGET`` keyword to
  support resolving target-dependent generator expressions.

* The :command:`file` gained sub-command `REAL_PATH` to compute a path with
  symlinks resolved.

* The :command:`find_package` command learned to handle a version range.

* The :command:`separate_arguments` command gained new ``PROGRAM`` option to
  search program.

* The :command:`set_property`, :command:`get_property`,
  and :command:`get_directory_property` commands' ``DIRECTORY``
  options now accept references to binary directory paths,
  such as the value of :variable:`CMAKE_CURRENT_BINARY_DIR`.

* The :command:`string` command gained set of new ``JSON`` sub commands
  to provide JSON parsing capabilities.

Variables
---------

* The :variable:`CMAKE_CLANG_VFS_OVERLAY` variable was added to tell
  Clang to use a VFS overlay to support the Windows SDK when
  cross-compiling from hosts with case-sensitive filesystems.

* The :variable:`CMAKE_MFC_FLAG` variable now supports generator expressions.

* The :variable:`CMAKE_OPTIMIZE_DEPENDENCIES` variable was added to
  initialize the new :prop_tgt:`OPTIMIZE_DEPENDENCIES` target property and
  avoid unnecessarily building dependencies for a static library.

* The :variable:`CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION_MAXIMUM` variable
  was added to tell the :ref:`Visual Studio Generators` what maximum
  version of the Windows SDK to choose.

Properties
----------

* The :prop_tgt:`EXCLUDE_FROM_ALL` target property now supports
  :manual:`generator expressions <cmake-generator-expressions(7)>`.

* The :prop_tgt:`OPTIMIZE_DEPENDENCIES` target property was added to
  avoid unnecessarily building dependencies for a static library.

* The :prop_tgt:`PCH_INSTANTIATE_TEMPLATES` target property was added to enable
  template instantiation in the precompiled header. This is enabled by default
  and offers a roughly 20% compile time improvement. Currently only supported
  by Clang 11.

* The :prop_tgt:`WIN32_EXECUTABLE` target property now supports
  :manual:`generator expressions <cmake-generator-expressions(7)>`.

Modules
-------

* The :module:`CheckCompilerFlag` module has been added to
  generalize :module:`CheckCCompilerFlag` and
  :module:`CheckCXXCompilerFlag` to more languages.
  It also supports the ``CUDA`` and ``ISPC`` languages.

* The :module:`CheckLinkerFlag` module now supports the ``CUDA`` language.

* The :module:`CheckSourceCompiles` module has been added to
  generalize :module:`CheckCSourceCompiles` and
  :module:`CheckCXXSourceCompiles` to more languages.
  It also supports the ``CUDA`` and ``ISPC`` languages.

* The :module:`CheckSourceRuns` module has been added to
  generalize :module:`CheckCSourceRuns` and
  :module:`CheckCXXSourceRuns` to more languages.
  It also supports the ``CUDA`` language.

* :module:`CMakePackageConfigHelpers` module learned to manage version range.

* The :module:`FindCUDAToolkit` module gained support for finding CUDA
  toolkits that do not contain ``nvcc``, as well as for finding scattered
  toolkit installations when cross-compiling.

* The :module:`FindPackageHandleStandardArgs` module learned to handle
  version range. It also gained the ``find_package_check_version()`` command to
  check the validity of a version against version-related arguments of
  :command:`find_package` command.

* The :module:`FindPython3`, :module:`FindPython2` and :module:`FindPython`
  modules gained the capability to manage a version range.

* The :module:`FindPython3`, :module:`FindPython2` and :module:`FindPython`
  modules provide, respectively, the variable ``Python3_LINK_OPTIONS``,
  ``Python2_LINK_OPTIONS`` and ``Python_LINK_OPTIONS`` for link options.

* The :module:`FindSDL` module now provides:

  * imported target ``SDL::SDL``,

  * result variables ``SDL_LIBRARIES`` and ``SDL_INCLUDE_DIRS``,

  * version variables ``SDL_VERSION``, ``SDL_VERSION_MAJOR``
    ``SDL_VERSION_MINOR``, and ``SDL_VERSION_PATCH``.

* :module:`FindSWIG` module gains the capability to manage a version range.

* The :module:`FindTIFF` module gained a ``CXX`` component to
  find the ``tiffxx`` library containing C++ bindings.

* The :module:`FindVulkan` module now provides a ``Vulkan::glslc`` imported
  target and associated ``Vulkan_GLSLC_EXECUTABLE`` variable which contain
  the path to the GLSL SPIR-V compiler.

* :module:`UseSWIG` module gains new source file properties ``OUTPUT_DIR`` and
  ``OUTFILE_DIR`` to manage output directories on per source basis.

CTest
-----

* :manual:`ctest(1)` now supports ``compute-sanitizer`` (``cuda-memcheck``) as
  ``CTEST_MEMORYCHECK_COMMAND``.  The different tools (memcheck, racecheck,
  synccheck, initcheck) supplied by ``compute-sanitizer`` can be selected by
  adding appropriate flags to the ``CTEST_MEMORYCHECK_COMMAND_OPTIONS``
  variable.  The default flags are ``--tool memcheck --leak-check full``.

CPack
-----

* CPack gained the :variable:`CPACK_PRE_BUILD_SCRIPTS`,
  :variable:`CPACK_POST_BUILD_SCRIPTS`, and :variable:`CPACK_PACKAGE_FILES`
  variables.

* The :cpack_gen:`CPack External Generator` gained the
  :variable:`CPACK_EXTERNAL_BUILT_PACKAGES` variable.

* The :cpack_gen:`CPack WIX Generator` gained a
  :variable:`CPACK_WIX_CUSTOM_XMLNS` option to specify custom XML namespaces.

Other
-----

* :ref:`Interface Libraries` may now have source files added via
  :command:`add_library` or :command:`target_sources`.  Those
  with sources will be generated as part of the build system.

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

* Compatibility with versions of CMake older than 2.8.12 is now deprecated
  and will be removed from a future version.  Calls to
  :command:`cmake_minimum_required` or :command:`cmake_policy` that set
  the policy version to an older value now issue a deprecation diagnostic.

* An explicit deprecation diagnostic was added for policy ``CMP0071``
  (``CMP0071`` and below were already deprecated).
  The :manual:`cmake-policies(7)` manual explains that the OLD behaviors
  of all policies are deprecated and that projects should port to the
  NEW behaviors.

* macOS SDKs older than 10.5 are no longer supported.

* :manual:`cmake-gui(1)` now requires Qt5.
  Support for compiling with Qt4 has been removed.

* The :manual:`cmake(1)` command-line option ``--warn-unused-vars`` has
  been removed and is now silently ignored.  The option has not worked
  correctly since CMake 3.3.

Documentation
=============

The following guides have been added:

* :guide:`IDE Integration Guide`
* :guide:`Importing and Exporting Guide`

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

* Building for macOS will now use the latest SDK available on the system,
  unless the user has explicitly chosen a SDK using
  :variable:`CMAKE_OSX_SYSROOT`.  The deployment target or system macOS
  version will not affect the choice of SDK.

* The :variable:`CMAKE_<LANG>_COMPILER` variable may now be used to
  store "mandatory" compiler flags like the :envvar:`CC` and other environment
  variables.

* The :variable:`CMAKE_<LANG>_FLAGS_INIT` variable will now be considered
  during the compiler identification check if other sources like
  :variable:`CMAKE_<LANG>_FLAGS` or :envvar:`CFLAGS` are not set.

* The :command:`find_program` command now requires permission to execute
  but not to read the file found.  See policy :policy:`CMP0109`.

* An imported target missing its location property fails during generation
  if the location is used.  See policy :policy:`CMP0111`.

* The following target-based generator expressions that query for directory or
  file name components no longer add a dependency on the evaluated target.
  See policy :policy:`CMP0112`.

  - ``TARGET_FILE_DIR``
  - ``TARGET_LINKER_FILE_BASE_NAME``
  - ``TARGET_LINKER_FILE_NAME``
  - ``TARGET_LINKER_FILE_DIR``
  - ``TARGET_SONAME_FILE_NAME``
  - ``TARGET_SONAME_FILE_DIR``
  - ``TARGET_PDB_FILE_NAME``
  - ``TARGET_PDB_FILE_DIR``
  - ``TARGET_BUNDLE_DIR``
  - ``TARGET_BUNDLE_CONTENT_DIR``

* :ref:`Makefile Generators` no longer repeat custom commands from target
  dependencies.  See policy :policy:`CMP0113`.

* The :module:`ExternalProject` module handling of step target dependencies
  has been revised.  See policy :policy:`CMP0114`.

* The :prop_tgt:`OSX_ARCHITECTURES` target property is now respected
  for the ``ASM`` language.

* If ``CUDA`` compiler detection fails with user-specified
  :variable:`CMAKE_CUDA_ARCHITECTURES` or
  :variable:`CMAKE_CUDA_HOST_COMPILER`, an error is raised.
