I am proud to announce the first CMake 3.15 release candidate.
https://cmake.org/download/

Documentation is available at:
https://cmake.org/cmake/help/v3.15

Release notes appear below and are also published at
https://cmake.org/cmake/help/v3.15/release/3.15.html

Some of the more significant changes in CMake 3.15 are:

  • The “CMAKE_MSVC_RUNTIME_LIBRARY” variable and
    “MSVC_RUNTIME_LIBRARY” target property were introduced to select the
    runtime library used by compilers targeting the MSVC ABI. See policy
    “CMP0091”.
  • With MSVC-like compilers the value of “CMAKE__FLAGS” no
    longer contains warning flags like “/W3” by default. See policy
    “CMP0092”.
  • The “Clang” compiler variant on Windows that targets the MSVC ABI
    but has a GNU-like command line is now supported.
  • Preliminary support for the “Swift” language was added to the
    “Ninja” generator.
  • The “$<COMPILE_LANG_AND_ID:…>” generator expression was
    introduced to allow specification of compile options for target
    files based on the “CMAKE__COMPILER_ID” and “LANGUAGE” of each
    source file.
  • The “generator expressions” “C_COMPILER_ID”, “CXX_COMPILER_ID”,
    “CUDA_COMPILER_ID”, “Fortran_COMPILER_ID”, “COMPILE_LANGUAGE”,
    “COMPILE_LANG_AND_ID”, and “PLATFORM_ID” learned to support matching
    one value from a comma-separated list.
  • The “CMAKE_FIND_PACKAGE_PREFER_CONFIG” variable was added to tell
    “find_package()” calls to look for a package configuration file
    first even if a find module is available.
  • The “PUBLIC_HEADER” and “PRIVATE_HEADER” properties may now be set
    on Interface Libraries. The headers specified by those properties
    can be installed using the “install(TARGETS)” command by passing the
    “PUBLIC_HEADER” and “PRIVATE_HEADER” arguments respectively.
  • The “CMAKE_VS_JUST_MY_CODE_DEBUGGING” variable and
    “VS_JUST_MY_CODE_DEBUGGING” target property were added to enable the
    Just My Code feature of the Visual Studio Debugger when compiling
    with MSVC cl 19.05 and higher.
  • The “FindBoost” module was reworked to expose a more consistent
    user experience between its “Config” and “Module” modes and with
    other find modules in general.
  • The “message()” command learned new types: “NOTICE”, “VERBOSE”,
    “DEBUG” and “TRACE”.
  • The “export(PACKAGE)” command now does nothing unless enabled via
    “CMAKE_EXPORT_PACKAGE_REGISTRY”. See policy “CMP0090”.
Changes made since CMake 3.14 include the following.


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


Generators
----------

* The "Xcode" generator now supports per-target schemes. See the
  "CMAKE_XCODE_GENERATE_SCHEME" variable and "XCODE_GENERATE_SCHEME"
  target property.

* The "Green Hills MULTI" generator has been updated:

  * It now supports the "add_custom_command()" and
    "add_custom_target()" commands.

  * It is now available on Linux.


Languages
---------

* Preliminary support for the "Swift" language was added to the
  "Ninja" generator:

  * Use the "SWIFTC" environment variable to specify a compiler.

  * The "Swift_DEPENDENCIES_FILE" target property and
    "Swift_DEPENDENCIES_FILE" source file property were added to
    customize dependency files.

  * The "Swift_MODULE_NAME" target property was added to customize
    the Swift module name.

  * The "Swift_DIAGNOSTICS_FILE" source property was added to
    indicate where to write the serialised Swift diagnostics.

  The Swift support is experimental, not considered stable, and may
  change in future releases of CMake.


Compilers
---------

* The "Clang" compiler variant on Windows that targets the MSVC ABI
  but has a GNU-like command line is now supported.

* Support for the Clang-based ARM compiler was added with compiler
  id "ARMClang".

* Support was added for the IAR compiler architectures Renesas RX,
  RL78, RH850 and Texas Instruments MSP430.

* Support was added for the IAR compilers built for Linux (IAR
  BuildLx).


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

* The "CMAKE_GENERATOR" environment variable was added to specify a
  default generator to use when "cmake(1)" is run without a "-G"
  option.  Additionally, environment variables
  "CMAKE_GENERATOR_PLATFORM", "CMAKE_GENERATOR_TOOLSET", and
  "CMAKE_GENERATOR_INSTANCE" were created to configure the generator.

* The "cmake(1)" "--build" tool "--target" parameter gained support
  for multiple targets, e.g. "cmake --build . --target Library1
  Library2". It now also has a short form "-t" alias, e.g. "cmake
  --build . -t Library1 Library2".

* The "cmake(1)" command gained a new "--install" option. This may
  be used after building a project to run installation without using
  the generated build system or the native build tool.

* The "cmake(1)" command learned a new CLI option "--loglevel".

* The "cmake(1)" "-E remove_directory" command-line tool learned to
  support removing multiple directories.

* The "cmake(1)" "-E tar" tool has been improved:

  * It now continues adding files to an archive even if some of the
    files are not readable.  This behavior is more consistent with the
    classic "tar" tool.

  * It now parses all flags, and if an invalid flag was provided, a
    warning is issued.

  * It now displays an error if no action flag was specified, along
    with a list of possible actions: "t" (list), "c" (create) or "x"
    (extract).

  * It now supports extracting ("-x") or listing ("-t") only
    specific files or directories.

  * It now supports Zstandard compression with a "--zstd" option.
    Zstandard was designed to give a compression ratio comparable to
    that of the DEFLATE (zip) algorithm, but faster, especially for
    decompression.


Commands
--------

* The "add_custom_command()" and "add_custom_target()" commands
  gained a new "JOB_POOL" option that works with the "Ninja" generator
  to set the pool variable on the build statement.

* The "add_library()" command "ALIAS" option learned to support
  import libraries of the "UNKNOWN" type.

* The "cmake_parse_arguments()" command gained an additional
  "_KEYWORDS_MISSING_VALUES" output variable to report keyword
  arguments that were given by the caller with no values.

* The "execute_process()" command gained a "COMMAND_ECHO" option and
  supporting "CMAKE_EXECUTE_PROCESS_COMMAND_ECHO" variable to enable
  echoing of the command-line string before execution.

* The "file(INSTALL)" command learned a new argument,
  "FOLLOW_SYMLINK_CHAIN", which can be used to recursively resolve and
  install symlinks.

* "list()" learned new sub-commands: "PREPEND", "POP_FRONT" and
  "POP_BACK".

* The "message()" command learned new types: "NOTICE", "VERBOSE",
  "DEBUG" and "TRACE".

* The "string()" learned a new sub-command "REPEAT".


Variables
---------

* The "CMAKE_CROSSCOMPILING_EMULATOR" variable and corresponding
  "CROSSCOMPILING_EMULATOR" target property learned to support
  arguments to the emulator.

* The "CMAKE_FIND_PACKAGE_PREFER_CONFIG" variable was added to tell
  "find_package()" calls to look for a package configuration file
  first even if a find module is available.

* The "CMAKE_FRAMEWORK" variable was added to initialize the
  "FRAMEWORK" property on all targets.

* The "CMAKE_VS_JUST_MY_CODE_DEBUGGING" variable and
  "VS_JUST_MY_CODE_DEBUGGING" target property were added to enable the
  Just My Code feature of the Visual Studio Debugger when compiling
  with MSVC cl 19.05 and higher.

* The "CMAKE_MSVC_RUNTIME_LIBRARY" variable and
  "MSVC_RUNTIME_LIBRARY" target property were introduced to select the
  runtime library used by compilers targeting the MSVC ABI. See policy
  "CMP0091".

* The "CMAKE_PROJECT_INCLUDE" and "CMAKE_PROJECT_INCLUDE_BEFORE"
  variables were added to allow injection of custom code at the sites
  of "project()" calls without knowing the project name a priori.


Properties
----------

* The "ADDITIONAL_CLEAN_FILES" target property and
  "ADDITIONAL_CLEAN_FILES" directory property were added. They allow
  to register additional files that should be removed during the clean
  stage.

* The "PUBLIC_HEADER" and "PRIVATE_HEADER" properties may now be set
  on Interface Libraries. The headers specified by those properties
  can be installed using the "install(TARGETS)" command by passing the
  "PUBLIC_HEADER" and "PRIVATE_HEADER" arguments respectively.

* The "VS_PACKAGE_REFERENCES" target property was added to tell
  Visual Studio Generators to add references to "nuget" packages.

* The "VS_PROJECT_IMPORT" target property was added to allow managed
  Visual Studio project files to import external ".props" files.

* The "VS_NO_SOLUTION_DEPLOY" target property was added to tell
  Visual Studio Generators whether to deploy an artifact to the WinCE
  or Windows Phone target device.


Modules
-------

* The "FindBoost" module was reworked to expose a more consistent
  user experience between its “Config” and “Module” modes and with
  other find modules in general.

  * A new imported target "Boost::headers" is now defined (same as
    "Boost::boost").

  * New output variables "Boost_VERSION_MACRO",
    "Boost_VERSION_MAJOR", "Boost_VERSION_MINOR",
    "Boost_VERSION_PATCH", and "Boost_VERSION_COUNT" were added.

  * The "QUIET" argument passed to "find_package()" is no longer
    ignored in config mode.  Note that the CMake package shipped with
    Boost "1.70.0" ignores the "QUIET" argument passed to
    "find_package()".  This is fixed in the next Boost release.

  * The input switch "Boost_DETAILED_FAILURE_MSG" was removed.

  * "Boost_VERSION" now reports the version in "x.y.z" format in
    module mode.  See policy "CMP0093".

* The "FindCups" module now provides imported targets.

* The "FindEnvModules" module was added to use Lua- and TCL-based
  environment modules in CTest Scripts.

* The "FindGLEW" module now provides an interface more consistent
  with what upstream GLEW provides in its own CMake package files.

* The "FindPkgConfig" now populates "INTERFACE_LINK_OPTIONS"
  property of imported targets with other (non-library) linker flags.

* The "FindPostgreSQL" module learned to find debug and release
  variants separately.

* Modules "FindPython3", "FindPython2" and "FindPython" gained
  additional lookup strategies and controls, and a new default. See
  policy "CMP0094".

* Modules "FindPython", "FindPython2" and "FindPython3" gain a new
  target (respectively "Python::Module", "Python2::Module" and
  "Python3::Module") which can be used to develop Python modules.

* Modules "FindPython3", "FindPython2" and "FindPython" gain
  capability to control how virtual environments are handled.

* The "UseSWIG" module learned to manage alternate library names by
  passing "-interface       " for "python" language or
  "-dllimport       " for "CSharp" language to the "SWIG"
  compiler.


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

* The "generator expressions" "C_COMPILER_ID", "CXX_COMPILER_ID",
  "CUDA_COMPILER_ID", "Fortran_COMPILER_ID", "COMPILE_LANGUAGE",
  "COMPILE_LANG_AND_ID", and "PLATFORM_ID" learned to support matching
  one value from a comma-separated list.


CTest
-----

* The "ctest_submit()" command learned a new option: "BUILD_ID".
  This can be used to store the ID assigned to this build by CDash to
  a variable.

* The "ctest_update()" command learned to honor a new variable:
  "CTEST_UPDATE_VERSION_OVERRIDE". This can be used to specify the
  current version of your source tree rather than using the update
  command to discover the current version that is checked out.

CPack
-----

* The "CPack IFW Generator" gained a new
  "CPACK_IFW_PACKAGE_STYLE_SHEET" variable to customize the installer
  stylesheet.

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

* The "cmake-server(7)" mode has been deprecated and will be removed
  from a future version of CMake.  Please port clients to use the
  "cmake-file-api(7)" instead.

* The "ADDITIONAL_MAKE_CLEAN_FILES" directory property is now
  deprecated.  Use the "ADDITIONAL_CLEAN_FILES" directory property
  instead.

* The variable "CMAKE_AUTOMOC_RELAXED_MODE" is considered
  deprecated. Support still exists but will be removed in future
  versions.

* The "export(PACKAGE)" command now does nothing unless enabled via
  "CMAKE_EXPORT_PACKAGE_REGISTRY". See policy "CMP0090".

* The "Xcode" generator now requires at least Xcode 5.

* An explicit deprecation diagnostic was added for policy "CMP0066"
  ("CMP0065" 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
=============

* CMake learned how to compile C++14 with the IBM AIX XL compiler
  and the SunPro compiler and to compile C++20 with the AppleClang
  compiler.

* With MSVC-like compilers the value of "CMAKE__FLAGS" no
  longer contains warning flags like "/W3" by default. See policy
  "CMP0092".

* IBM Clang-based XL compilers that define "__ibmxl__" now use the
  compiler id "XLClang" instead of "XL".  See policy "CMP0089".

* The "file(REMOVE)" and "file(REMOVE_RECURSE)" commands were
  changed to ignore empty arguments with a warning instead of treating
  them as a relative path and removing the contents of the current
  directory.

1 comment to CMake 3.15.0-rc1 is ready for testing

  1. Thanks for the team’s work on the GNU-like clang compatibility. I just started a project hoping to use this a few weeks ago not realizing it wouldn’t work as of 3.14, and got lucky to stumble across the Issue Board and realized it was being worked on right then. I’ll be putting it to use right away with the release candidate!

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