CMake 3.18.0-rc1 is ready for testing

I am proud to announce the first CMake 3.18 release candidate.
https://cmake.org/download/

Documentation is available at:
https://cmake.org/cmake/help/v3.18

Release notes appear below and are also published at
https://cmake.org/cmake/help/v3.18/release/3.18.html

Some of the more significant changes in CMake 3.18 are:

• The “CUDA” language can now be compiled using Clang.
  This is experimental and still under development.
• “cmake(1)” gained support for profiling of CMake scripts through the
  parameters “–profiling-output” and “–profiling-format”.
• The “add_library()” and “add_executable()” commands learned to
  create Alias Targets referencing non-“GLOBAL” Imported Targets.
• The “cmake_language()” command was added for meta-operations on
  scripted or built-in commands, starting with a mode to “CALL” other
  commands, and “EVAL CODE” to inplace evaluate a CMake script.
• The “file(CONFIGURE)” subcommand was created in order to replicate
  the “configure_file()” functionality without resorting to a pre-
  existing file on disk as input. The content is instead passed as a
  string.
• The “find_program()”, “find_library()”, “find_path()” and
  “find_file()” commands gained a new “REQUIRED” option that will stop
  processing with an error message if nothing is found.
• A “CMAKE_CUDA_ARCHITECTURES” variable was added to specify CUDA
  output architectures. Users are encouraged to use this instead of
  specifying options manually, as this approach is compiler-agnostic.
  The variable is initialized automatically when
  “CMAKE_CUDA_COMPILER_ID” is “NVIDIA”. The variable is used to
  initialize the new “CUDA_ARCHITECTURES” target property. See policy
  “CMP0104”.
• The “UNITY_BUILD_MODE” target property was added to tell generators
  which algorithm (“BATCH”, “GROUP”) to use for grouping included source
  files.
• The “CheckLinkerFlag” module has been added to provide a facility to
  check validity of link flags.
• The “$<DEVICE_LINK:…>” and “$<HOST_LINK:…>” “generator
  expressions” were added to manage device and host link steps.
• The “$<LINK_LANGUAGE:…>” and “$<LINK_LANG_AND_ID:…>” “generator expressions” were added.
• “ctest(1)” gained a new “CTEST_RESOURCE_SPEC_FILE” variable, which
  can be used to specify a resource specification file.
• “ccmake(1)” learned to read a “CCMAKE_COLORS” environment variable
  to customize colors.
• On Windows, the “Ninja” and “Ninja Multi-Config” generators, when a
  compiler is not explicitly specified, now select the first compiler
  (of any name) found in directories listed by the “PATH” environment
  variable.

----------------------------------------------------------------------------
CMake 3.18 Release Notes
************************

Changes made since CMake 3.17 include the following.


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


Languages
---------

* The "CUDA" language can now be compiled using Clang.
  This is experimental and still under development.


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

* "cmake(1)" gained support for profiling of CMake scripts through the
  parameters "--profiling-output" and "--profiling-format".

* "cmake(1)" gained a "cat" command line option that can be used to
  concatenate files and print them on standard output.


Commands
--------

* The "add_library()" and "add_executable()" commands learned to
  create Alias Targets referencing non-"GLOBAL" Imported Targets.

* The "cmake_language()" command was added for meta-operations on
  scripted or built-in commands, starting with a mode to "CALL" other
  commands, and "EVAL CODE" to inplace evaluate a CMake script.

* The "execute_process()" command gained the "ECHO_OUTPUT_VARIABLE"
  and "ECHO_ERROR_VARIABLE" options.

* The "export()" command now raise an error if used multiple times
  with same "FILE" without "APPEND". See policy "CMP0103".

* The "file()" command gained the "ARCHIVE_CREATE" and
  "ARCHIVE_EXTRACT" subcommands to expose the "cmake(1)" "-E tar"
  functionality to CMake scripting code.

* The "file(CONFIGURE)" subcommand was created in order to replicate
  the "configure_file()" functionality without resorting to a pre-
  existing file on disk as input. The content is instead passed as a
  string.

* The "file(UPLOAD)" command gained "TLS_VERIFY" and "TLS_CAINFO"
  options to control server certificate verification.

* The "find_program()", "find_library()", "find_path()" and
  "find_file()" commands gained a new "REQUIRED" option that will stop
  processing with an error message if nothing is found.

* The "get_property()" command with "SOURCE" scope gained the
  "DIRECTORY" and "TARGET_DIRECTORY" options to get a property from
  the provided directory scope.

* The "get_source_file_property()" command gained the "DIRECTORY" and
  "TARGET_DIRECTORY" options to get a property from the provided
  directory scope.

* The "list()" operation "SORT" gained the "NATURAL" sort option to
  sort using natural order (see "strverscmp(3)" manual).

* The "set_property()" command with the "SOURCE" scope gained the
  "DIRECTORY" and "TARGET_DIRECTORY" options to set properties in the
  provided directory scopes.

* The "set_source_files_properties()" command gained the "DIRECTORY"
  and "TARGET_DIRECTORY" options to set properties in the provided
  directory scopes.

* The "string()" command learned a new "HEX" sub-command, which
  converts strings into their hexadecimal representation.


Variables
---------

* A "CMAKE_CUDA_ARCHITECTURES" variable was added to specify CUDA
  output architectures.  Users are encouraged to use this instead of
  specifying options manually, as this approach is compiler-agnostic.
  The variable is initialized automatically when
  "CMAKE_CUDA_COMPILER_ID" is "NVIDIA". The variable is used to
  initialize the new "CUDA_ARCHITECTURES" target property.  See policy
  "CMP0104".

* The "CMAKE_PCH_WARN_INVALID" variable was added to initialize the
  "PCH_WARN_INVALID" target property to allow the removal of the
  precompiled header invalid warning.


Properties
----------

* The "CUDA_ARCHITECTURES" target property was added to specify CUDA
  output architectures. Users are encouraged to use this instead of
  specifying options manually, as this approach is compiler-agnostic.
  The property is initialized by the new "CMAKE_CUDA_ARCHITECTURES"
  variable.  See policy "CMP0104".

* The "Fortran_PREPROCESS" target property and "Fortran_PREPROCESS"
  source-file property were added to control preprocessing of Fortran
  source files.

* The "FRAMEWORK_MULTI_CONFIG_POSTFIX_" target property and
  associated "CMAKE_FRAMEWORK_MULTI_CONFIG_POSTFIX_" variable
  were created to allow adding a postfix to the name of a framework
  file name when using a multi-config generator.

* The "OBJECT_OUTPUTS" source file property now supports "generator
  expressions".

* The "UNITY_BUILD_MODE" target property was added to tell generators
  which algorithm to use for grouping included source files.

* The "VS_SOURCE_SETTINGS_" target property was added to tell
  Visual Studio Generators for VS 2010 and above to add metadata to
  non-built source files using "".

* The "VS_SETTINGS" source file property was added to tell Visual
  Studio Generators for VS 2010 and above to add metadata to a non-
  built source file.

* The "VS_PLATFORM_TOOLSET" target property was added to tell Visual
  Studio Generators for VS 2010 and above to override the platform
  toolset.

* The "VS_SOLUTION_DEPLOY" target property was added to tell Visual
  Studio Generators for VS 2010 and above to mark a target for
  deployment even when not building for Windows Phone/Store/CE.


Modules
-------

* The "CheckLinkerFlag" module has been added to provide a facility to
  check validity of link flags.

* The "ExternalProject" module "ExternalProject_Add()" command gained
  a new "GIT_REMOTE_UPDATE_STRATEGY" keyword.  This can be used to
  specify how failed rebase operations during a git update should be
  handled. The "CMAKE_EP_GIT_REMOTE_UPDATE_STRATEGY" variable was also
  added as a global default and is honored by both the
  "ExternalProject" and "FetchContent" modules.

* The "FetchContent" module "FetchContent_Declare()" command now
  supports a "SOURCE_SUBDIR" option.  It can be used to direct
  "FetchContent_MakeAvailable()" to look in a different location for
  the "CMakeLists.txt" file.

* The "FindBLAS" module now provides an imported target.

* The "FindLAPACK" module now provides an imported target.

* The "FindPython3", "FindPython2" and "FindPython" modules:

  * gained the possibility to create per-artifact cache variables for
    interactive editing in "cmake-gui(1)" and "ccmake(1)".

  * gained sub-components "Development.Module" and "Development.Embed"
    under the "Development" component.

  * gained the capability to specify which Python implementations to
    find, including "IronPython" and "PyPy".

* The "FindRuby" module input and output variables were all renamed
  from "RUBY_" to "Ruby_" for consistency with other find modules.
  Input variables of the old case will be honored if provided, and
  output variables of the old case are always provided.

* The "FindSWIG" module now accepts target languages as  "COMPONENTS"
  and "OPTIONAL_COMPONENTS" arguments to "find_package".

* The "GoogleTest" module "gtest_discover_tests()" command:

  * gained a new "DISCOVERY_MODE" option to control when the test
    discovery step is run.  It offers a new "PRE_TEST" setting to run
    the discovery at test time instead of build time.

  * gained a new optional parameter "XML_OUTPUT_DIR". When set the
    JUnit XML test results are stored in that directory.

* The "FindLibXslt" module now provides imported targets.

* The "UseSWIG" module now supports Fortran as a target language if
  the "SWIG_EXECUTABLE" is SWIG-Fortran.


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

* The "$" and "$" "generator
  expressions" were added to manage device and host link steps.

* The "$" and "$" "generator
  expressions" were added.


CTest
-----

* "ctest(1)" gained a new "CTEST_RESOURCE_SPEC_FILE" variable, which
  can be used to specify a resource specification file.

* "ctest(1)" gained a "--stop-on-failure" option, which can be used to
  stop running the tests once one has failed.

* The "ctest_test()" command gained a "STOP_ON_FAILURE" option which
  can be used to stop running the tests once one has failed.

* The "CTestCoverageCollectGCOV" module
  "ctest_coverage_collect_gcov()" command gained a
  "TARBALL_COMPRESSION" option to control compression of the tarball
  of collected results.


CPack
-----

* The "CPack Archive Generator"’s "TXZ" format learned the
  "CPACK_ARCHIVE_THREADS" variable to enable parallel compression.
  Requires support in the "liblzma" used by CMake.

* The "CPack NSIS Generator" gained a new variable
  "CPACK_NSIS_MANIFEST_DPI_AWARE" to declare that the installer is
  DPI-aware.

* The "CPack RPM Generator" gained "CPACK_RPM_PRE_TRANS_SCRIPT_FILE"
  "CPACK_RPM_POST_TRANS_SCRIPT_FILE" variables to specify pre- and
  post-trans scripts.


Other
-----

* "cmake-gui(1)" now populates its generator selection widget default
  value from the "CMAKE_GENERATOR" environment variable.
  Additionally, environment variables "CMAKE_GENERATOR_PLATFORM" and
  "CMAKE_GENERATOR_TOOLSET" are used to populate their respective
  widget defaults.

* "ccmake(1)" learned to read a "CCMAKE_COLORS" environment variable
  to customize colors.


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

* The "Documentation" module has been deprecated via "CMP0106". This
  module was essentially VTK code that CMake should not be shipping
  anymore.

* An explicit deprecation diagnostic was added for policy "CMP0070"
  and policy "CMP0071" ("CMP0069" 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.


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

* On Windows, the "Ninja" and "Ninja Multi-Config" generators, when a
  compiler is not explicitly specified, now select the first compiler
  (of any name) found in directories listed by the "PATH" environment
  variable.

* The "LINK_OPTIONS" and "INTERFACE_LINK_OPTIONS" target properties
  are now used for the device link step. See policy "CMP0105".

* Creation of an "ALIAS" target overwriting an existing target now
  raises an error. See policy "CMP0107".

* Linking a target to itself through an alias now raises an error. See
  policy "CMP0108".

* The "FindPackageHandleStandardArgs" module option "REQUIRED_VARS" is
  now optional if "HANDLE_COMPONENTS" is specified.

* The "source_group()" command now also recognizes forward slashes as
  subgroup delimiters, not just backslashes.

* "ctest(1)" now logs environment variables that it sets for each
  test, either due to the "ENVIRONMENT" property or the resource
  allocation feature, and submits this log to CDash. It does not log
  environment variables that were set outside of CTest.

* When building CMake itself from source and not using a system-
  provided libcurl, HTTP/2 support is now enabled for commands
  supporting network communication via "http(s)", such as
  "file(DOWNLOAD)", "file(UPLOAD)", and "ctest_submit()". The
  precompiled binaries provided on "cmake.org" now support HTTP/2.