CMake 4.0.0-rc1 is ready for testing

I am proud to announce the first CMake 4.0 release candidate.
https://cmake.org/download/

Documentation is available at:
https://cmake.org/cmake/help/v4.0

Release notes appear below and are also published at
https://cmake.org/cmake/help/v4.0/release/4.0.html

Release milestone is available at:
release milestone

Some of the most significant changes in CMake 4.0 are:

• The “CMAKE_POLICY_VERSION_MINIMUM” variable was added to help
  packagers and end users try to configure existing projects that have
  not been updated to work with supported CMake versions.

• The “$<PATH>” generator expression gained the “NATIVE_PATH”
  operation to convert a CMake path into a native one.

• Compatibility with versions of CMake older than 3.5 has been
  removed. Calls to “cmake_minimum_required()” or “cmake_policy()”
  that set the policy version to an older value now issue an error.
  Note that calls to those commands can still support older versions
  of CMake by using their “VERSION” arguments’ “<min>…<max>” syntax.
  This requires only the “<min>” version of CMake, but when running a
  newer version, sets policies up to the “<max>” version.

• On macOS with Ninja Generators and Makefile Generators, when a
  compiler is found in “/usr/bin”, it is now used as-is and is no
  longer mapped to the corresponding compiler inside Xcode.

• Builds targeting macOS no longer choose any SDK or pass an
  “-isysroot” flag to the compiler by default. Instead, compilers are
  expected to choose a default macOS SDK on their own. In order to
  use a compiler that does not do this, users must now specify
  “-DCMAKE_OSX_SYSROOT=macosx” when configuring their build.

• Precompiled SunOS “sparc” and “i386” binaries are now provided on
  cmake.org.

CMake 4.0 Release Notes
***********************

Changes made since CMake 3.31 include the following.


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


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

* The "cmake-file-api(7)" "codemodel" version 2 "version" field has
  been updated to 2.8.

* The "cmake-file-api(7)" "codemodel" version 2 "target" object gained
  a new "debugger" field.


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

* The "cmake --link-no-warning-as-error" option was added to suppress
  the effects of the "LINK_WARNING_AS_ERROR" target property and
  "CMAKE_LINK_WARNING_AS_ERROR" variable.

* The "cmake --project-file" option was added to specify an alternate
  filename for "CMakeLists.txt" files.  This is intended for temporary
  use by developers during an incremental transition and not for
  publication of a final product.  CMake will always emit a warning
  when the project file is anything other than "CMakeLists.txt".


Commands
--------

* The "target_link_libraries()" command now supports the "LINKER:"
  prefix.


Variables
---------

* The "AIX" and "CMAKE_HOST_AIX" variables are now set to true when
  the target or host system is AIX, respectively.

* Linker flag variables learned to support the "LINKER:" prefix:

  * "CMAKE_EXE_LINKER_FLAGS"

  * "CMAKE_EXE_LINKER_FLAGS_<CONFIG>"

  * "CMAKE_SHARED_LINKER_FLAGS"

  * "CMAKE_SHARED_LINKER_FLAGS_<CONFIG>"

  * "CMAKE_MODULE_LINKER_FLAGS"

  * "CMAKE_MODULE_LINKER_FLAGS_<CONFIG>"

  See policy "CMP0181".

* The "CMAKE_EXECUTE_PROCESS_COMMAND_ERROR_IS_FATAL" variable was
  added to specify the "execute_process()" command's default
  "COMMAND_ERROR_IS_FATAL" behavior.

* The "CMAKE_<LANG>_LINK_MODE" and "CMAKE_<LANG>_DEVICE_LINK_MODE"
  variables were added to provide information on how the link step is
  done.

* The "CMAKE_LINK_WARNING_AS_ERROR" variable and corresponding
  "LINK_WARNING_AS_ERROR" target property were added to link using a
  linker-specific flag to treat warnings as errors.

* The "CMAKE_MSVC_RUNTIME_CHECKS" variable and "MSVC_RUNTIME_CHECKS"
  target property were introduced to select runtime checks for
  compilers targeting the MSVC ABI. See policy "CMP0184".

* The "CMAKE_POLICY_VERSION_MINIMUM" variable was added to help
  packagers and end users try to configure existing projects that have
  not been updated to work with supported CMake versions.

* The "CMAKE_XCODE_SCHEME_LLDB_INIT_FILE" variable and corresponding
  "XCODE_SCHEME_LLDB_INIT_FILE" target property were added to tell the
  "Xcode" generator what to put in the scheme's "LLDB Init File"
  setting.

* The "CMAKE_XCODE_SCHEME_TEST_CONFIGURATION" variable and
  corresponding "XCODE_SCHEME_TEST_CONFIGURATION" target property were
  added to tell the "Xcode" generator what to put in the scheme's
  "Build Configuration" setting for the test action.


Properties
----------

* The "DEBUGGER_WORKING_DIRECTORY" target property and corresponding
  "CMAKE_DEBUGGER_WORKING_DIRECTORY" variable were added to tell
  generators what debugger working directory should be set for
  targets.

* The "STATIC_LIBRARY_OPTIONS" target property now supports an
  "ARCHIVER:" prefix to pass options to the archiver through the
  compiler driver in a portable way.

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

* The "VS_CUSTOM_COMMAND_DISABLE_PARALLEL_BUILD" source file property
  was added to tell Visual Studio Generators not to run a custom
  command in parallel.

* The "VS_SOLUTION_ITEMS" directory property was added to tell Visual
  Studio Generators to attach files directly to the Solution (".sln").


Modules
-------

* The "ExternalData" module gained a "ExternalData_HTTPHEADERS"
  variable to specify HTTP headers.

* The "ExternalProject" module's "ExternalProject_Add()" command
  gained an "INSTALL_JOB_SERVER_AWARE" option to enable integration of
  the GNU Make job server when using an explicit "INSTALL_COMMAND"
  with Makefile Generators.

* The "FeatureSummary" module "add_feature_info()" command now
  supports full Condition Syntax. See policy "CMP0183".

* The "FindBISON" module "bison_target()" command gained an "OPTIONS"
  option to specify Bison command-line options.

* The "FindCURL" module now provides a "CURL_VERSION" result variable
  to match upstream cURL's CMake package.

* The "FindFLEX" module "flex_target()" command gained an "OPTIONS"
  option to specify Flex command-line options.

* The "FindPatch" module now supports running in cmake -P script mode
  by skipping the creation of the imported target.

* The "FindProtobuf" module "protobuf_generate()" command gained a
  "PROTOC_EXE" option to specify a custom "protoc" executable.

* The "FindPython", "FindPython2", and "FindPython3" modules gained
  the possibility to do multiple calls in the same directory by using,
  respectively, the variables "Python_ARTIFACTS_PREFIX",
  "Python2_ARTIFACTS_PREFIX", and "Python3_ARTIFACTS_PREFIX".

* The "FindRuby" module learned to find rbenv-provided installations.


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

* The "$<PATH>" generator expression gained the "NATIVE_PATH"
  operation to convert a CMake path into a native one.


CTest
-----

* The "ctest --interactive-debug-mode" option on Windows now enables
  Windows Error Reporting by default in test processes, allowing them
  to creating debug popup windows and core dumps. This restores
  behavior previously removed by CMake 3.11 after updates to "libuv"
  made it possible.


CPack
-----

* The "CPack Archive Generator" learned to generated ".tar" packages
  without compression.

* The "CPack Archive Generator" now honors the
  "CPACK_ARCHIVE_FILE_NAME" variable for all packages. Previously,
  this variable worked only for component-based packages.


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

* Compatibility with versions of CMake older than 3.5 has been
  removed. Calls to "cmake_minimum_required()" or "cmake_policy()"
  that set the policy version to an older value now issue an error.
  Note that calls to those commands can still support older versions
  of CMake by using their "VERSION" arguments' "<min>...<max>" syntax.
  This requires only the "<min>" version of CMake, but when running a
  newer version, sets policies up to the "<max>" version.

* The "Visual Studio 14 2015" and "Visual Studio 15 2017" generators
  no longer support specifying a platform as part of the generator
  name.  See Visual Studio Platform Selection.

* The "CMAKE_<LANG>_USING_LINKER_MODE" variable is no longer used to
  determine the type of the contents of the
  "CMAKE_<LANG>_USING_LINKER_<TYPE>" variable. The
  "CMAKE_<LANG>_LINK_MODE" variable, set by CMake, is used instead.

* The "FindGDAL" module is now deprecated in favor of upstream GDAL's
  official CMake package configuration file. Port projects to the
  latter by calling "find_package(GDAL CONFIG)".  For further details,
  see GDAL's documentation on CMake integration.

* The "FindRuby" module no longer provides variables with the upper-
  case "RUBY_" prefix.  See policy "CMP0185".

* CTest's undocumented declarative scripting mode has been removed.
  This mode used to be triggered by a "ctest -S" script which did not
  call any CTest Commands unless "CTEST_RUN_CURRENT_SCRIPT" was
  explicitly set to "OFF".

* The "ctest_run_script()" command may no longer be called without any
  arguments.


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

* On macOS with Ninja Generators and Makefile Generators, when a
  compiler is found in "/usr/bin", it is now used as-is and is no
  longer mapped to the corresponding compiler inside Xcode.  The
  mapping was introduced by CMake 3.2 to allow build trees to continue
  to work with their original compiler even when "xcode-select"
  switches to a different Xcode installation.  However, the compilers
  inside Xcode cannot be used without explicit "-isysroot" flags and
  are therefore not suitable for passing to arbitrary third-party
  build systems.  Furthermore, the mapping behavior can override user-
  specified compiler paths.  Therefore, this behavior has been
  reverted.

* Builds targeting macOS no longer choose any SDK or pass an
  "-isysroot" flag to the compiler by default.  Instead, compilers are
  expected to choose a default macOS SDK on their own.  In order to
  use a compiler that does not do this, users must now specify
  "-DCMAKE_OSX_SYSROOT=macosx" when configuring their build.

* On AIX, "SHARED" library targets now produce a shared library
  archive by default.  See policy "CMP0182".

* The "cmake --preset" command no longer outputs a summary of the
  preset's CMake cache and environment variables by default.  That
  summary is now only shown when the message log level is set to
  "VERBOSE", "DEBUG", or "TRACE" via the   "cmake --log-level" option
  or the "CMAKE_MESSAGE_LOG_LEVEL" cache variable.

* Precompiled SunOS "sparc" and "i386" binaries are now provided on
  cmake.org.