CMake 3.19.0-rc1 is ready for testing

I am proud to announce the first CMake 3.19 release candidate.
    https://cmake.org/download/

Documentation is available at:
    https://cmake.org/cmake/help/v3.19

Release notes appear below and are also published at
    https://cmake.org/cmake/help/v3.19/release/3.19.html

Some of the more significant changes in CMake 3.19 are:

• “cmake(1)” and “cmake-gui(1)” now recognize “CMakePresets.json” and
  “CMakeUserPresets.json” files.
• The “Xcode” generator now uses the Xcode “new build system” when
  generating for Xcode 12.0 or higher. See the
  “CMAKE_XCODE_BUILD_SYSTEM” variable. One may use “-T buildsystem=1”
  to switch to the legacy build system.
• The Visual Studio Generators for VS 2015 and above gained support
  for the Visual Studio Tools for Android. One may now set
  “CMAKE_SYSTEM_NAME” to “Android” to generate “.vcxproj” files for
  the Android tools.
• CMake learned to support “ISPC” as a first-class language that can
  be enabled via the “project()” and “enable_language()” commands.
  “ISPC” is currently supported by the Makefile Generators and the
  “Ninja” generator on Linux, macOS, and Windows using the Intel ISPC
  compiler.
• “CUDA” language support for Clang now supports separable compilation
  (“CUDA_SEPARABLE_COMPILATION”)
• The “CMake GUI” now has an environment variable editor.
• The “cmake_path()” command was added for operations on filesystem
  paths.
• The “file(GENERATE)” command gained a new “TARGET” keyword to
  support resolving target-dependent generator expressions.
• The “CMAKE_OPTIMIZE_DEPENDENCIES” variable was added to initialize
  the new “OPTIMIZE_DEPENDENCIES” target property and avoid
  unnecessarily building dependencies for a static library.
• The “CheckCompilerFlag” module has been added to generalize
  “CheckCCompilerFlag” and “CheckCXXCompilerFlag” to more languages.
  It also supports the “CUDA” and “ISPC” languages.
• The “CheckSourceCompiles” module has been added to generalize
  “CheckCSourceCompiles” and “CheckCXXSourceCompiles” to more
  languages. It also supports the “CUDA” and “ISPC” languages.
• The “CheckSourceRuns” module has been added to generalize
  “CheckCSourceRuns” and “CheckCXXSourceRuns” to more languages. It
  also supports the “CUDA” language.
• The “FindCUDAToolkit” module gained support for finding CUDA
  toolkits that do not contain “nvcc”, as well as for finding
  scattered toolkit installations when cross-compiling.
• Interface Libraries may now have source files added via
  “add_library()” or “target_sources()”. Those with sources will be
  generated as part of the build system.
• Compatibility with versions of CMake older than 2.8.12 is now
  deprecated and will be removed from a future version. Calls to
  “cmake_minimum_required()” or “cmake_policy()” that set the policy
  version to an older value now issue a deprecation diagnostic.

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


Changes made since CMake 3.18 include the following.

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

Presets
-------

* "cmake(1)" and "cmake-gui(1)" now recognize "CMakePresets.json" and
"CMakeUserPresets.json" files.

Generators
----------

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

* The "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 "XCODE_LINK_BUILD_PHASE_MODE" target
property, which is initialized by a new
"CMAKE_XCODE_LINK_BUILD_PHASE_MODE" variable.

* The Visual Studio Generators for VS 2015 and above gained support
for the Visual Studio Tools for Android.  One may now set
"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 "project()" and "enable_language()" commands.
"ISPC" is currently supported by the Makefile Generators and the
"Ninja" generator on Linux, macOS, and Windows using the Intel ISPC
compiler.

* "CUDA" language support for Clang now includes:

* separable compilation ("CUDA_SEPARABLE_COMPILATION"), and

* finding scattered toolkit installations when cross-compiling.

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

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

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

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

* The "cmake(1)" command-line tool’s "--install" mode gained a "--
default-directory-permissions" option.

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

GUI
---

* The "CMake GUI" now has an environment variable editor.

Commands
--------

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

* The "cmake_language()" command gained a "DEFER" mode to schedule
command calls to occur at the end of processing a directory.

* The "cmake_path()" command was added for operations on filesystem
paths.

* The "configure_file()" command gained a "NO_SOURCE_PERMISSIONS"
option to suppress copying the input file’s permissions to the
output file.

* The "execute_process()" command gained a "COMMAND_ERROR_IS_FATAL"
option to specify a fatal error.

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

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

* The "file(DOWNLOAD)" command "" argument is now optional.  If
it is not specified, the file is not saved.

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

* The "file()" gained sub-command *REAL_PATH* to compute a path with
symlinks resolved.

* The "find_package()" command learned to handle a version range.

* The "separate_arguments()" command gained new "PROGRAM" option to
search program.

* The "set_property()", "get_property()", and
"get_directory_property()" commands’ "DIRECTORY" options now accept
references to binary directory paths, such as the value of
"CMAKE_CURRENT_BINARY_DIR".

* The "string()" command gained set of new "JSON" sub commands to
provide JSON parsing capabilities.

Variables
---------

* The "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 "CMAKE_MFC_FLAG" variable now supports generator expressions.

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

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

Properties
----------

* The "EXCLUDE_FROM_ALL" target property now supports "generator
expressions".

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

* The "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 "WIN32_EXECUTABLE" target property now supports "generator
expressions".

Modules
-------

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

* The "CheckLinkerFlag" module now supports the "CUDA" language.

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

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

* "CMakePackageConfigHelpers" module learned to manage version range.

* The "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 "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
"find_package()" command.

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

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

* The "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".

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

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

* The "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.

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

CTest
-----

* "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 "CPACK_PRE_BUILD_SCRIPTS",
"CPACK_POST_BUILD_SCRIPTS", and "CPACK_PACKAGE_FILES" variables.

* The "CPack External Generator" gained the
"CPACK_EXTERNAL_BUILT_PACKAGES" variable.

* The "CPack WIX Generator" gained a "CPACK_WIX_CUSTOM_XMLNS" option
to specify custom XML namespaces.

Other
-----

* Interface Libraries may now have source files added via
"add_library()" or "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
"cmake_minimum_required()" or "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 "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.

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

* The "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:

* "IDE Integration 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
"CMAKE_OSX_SYSROOT".  The deployment target or system macOS version
will not affect the choice of SDK.

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

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

* The "find_program()" command now requires permission to execute but
not to read the file found.  See policy "CMP0109".

* An imported target with a missing location now fails during
generation if the location is used.  See 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 "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"

* Makefile Generators no longer repeat custom commands from target
dependencies.  See policy "CMP0113".

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

* The "OSX_ARCHITECTURES" target property is now respected for the
"ASM" language.

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