CMake 3.20.0-rc3 is ready for testing

Announcements
1

I am proud to announce the third CMake 3.20 release candidate.
https://cmake.org/download/

Documentation is available at:
https://cmake.org/cmake/help/v3.20

Release notes appear below and are also published at
https://cmake.org/cmake/help/v3.20/release/3.20.html

Some of the more significant changes in CMake 3.20 are:

  • “cmake-presets(7)” gained support for build and test presets.

  • C++23 compiler modes may now be specified via the “CXX_STANDARD”,
    “CUDA_STANDARD”, or “OBJCXX_STANDARD” target properties, or via the
    “Compile Features” functionality’s “cxx_std_23” meta-feature.

  • The NVIDIA HPC SDK compilers are now supported with compiler id
    “NVHPC”.

  • CMake’s support for Cross Compiling for Android is now merged with
    the Android NDK’s toolchain file. They now have similar behavior,
    though some variable names differ.

  • The “cmake-file-api(7)” gained a new “toolchains” object kind that
    describes the compiler used for each enabled language.

  • “add_custom_command()” and “add_custom_target()” now support
    “generator expressions” in their “OUTPUT” and “BYPRODUCTS” options.

    Their “COMMAND”, “WORKING_DIRECTORY”, and “DEPENDS” options gained
    support for new generator expressions “$<COMMAND_CONFIG:…>” and
    “$<OUTPUT_CONFIG:…>” that control cross-config handling when using
    the “Ninja Multi-Config” generator.

  • The “cmake_path()” command was added for operations on filesystem
    paths.

  • The “target_sources()” command now supports targets created by the
    “add_custom_target()” command.

  • The “ExternalProject” module “ExternalProject_Add()” function gained
    a “CONFIGURE_HANDLED_BY_BUILD” option. This can be used to make
    subsequent runs of the configure step be triggered by the build step
    when an external project dependency rebuilds instead of always re-
    running the configure step in such cases.

  • “ctest(1)” gained a “–test-dir” option to specify the directory in
    which to look for tests.

  • The “cmake-server(7)” mode has been removed. Clients should use the
    “cmake-file-api(7)” instead.

  • The “WriteCompilerDetectionHeader” module has been deprecated via
    policy “CMP0120”. Projects should be ported away from it.

  • The “AddFileDependencies” module is deprecated. Port projects to use
    “set_property()” directly.

CMake 3.20 Release Notes

Changes made since CMake 3.19 include the following.

New Features

Presets

  • “cmake-presets(7)” gained support for build and test presets.

Generators

  • Makefile Generators, for some toolchains, now use the compiler to
    extract implicit dependencies while compiling source files.

Languages

  • C++23 compiler modes may now be specified via the “CXX_STANDARD”,
    “CUDA_STANDARD”, or “OBJCXX_STANDARD” target properties, or via the
    “Compile Features” functionality’s “cxx_std_23” meta-feature.

  • “CUDA” language support now works when “nvcc” is a symbolic link,
    for example due to a “ccache” or “colornvcc” wrapper script.

  • The “CUDAARCHS” environment variable was added for initializing
    “CMAKE_CUDA_ARCHITECTURES”. Useful in cases where the compiler
    default is unsuitable for the machine’s GPU.

Compilers

  • The NVIDIA HPC SDK compilers are now supported with compiler id
    “NVHPC”.

  • The Intel oneAPI NextGen LLVM compilers are now supported with
    compiler id “IntelLLVM”:

    • The “icx”/“icpx” C/C++ compilers on Linux, and the “icx” C/C++
      compiler on Windows, are fully supported as of oneAPI 2021.1.

    • The “ifx” Fortran compiler on Linux is partially supported. As of
      oneAPI 2021.1, “ifx” does not define several identification
      macros, so CMake identifies it as the classic “Intel” compiler.
      This works in many cases because “ifx” accepts the same command
      line parameters as “ifort”. A future version of oneAPI may fix
      this.

    • The “ifx” Fortran compiler on Windows is not yet supported.

    The Intel oneAPI Classic compilers (“icc”, “icpc”, and “ifort”)
    continue to be supported with compiler id “Intel”.

  • Support was added for the IAR STM8 compiler.

Platforms

  • CMake’s support for Cross Compiling for Android is now merged with
    the Android NDK’s toolchain file. They now have similar behavior,
    though some variable names differ. User-facing changes include:

    • “find_*” functions will search NDK ABI / API specific paths by
      default.

    • The default “CMAKE_BUILD_TYPE” for Android is now
      “RelWithDebInfo”.

    • The “CMAKE_ANDROID_NDK_VERSION” variable was added to report the
      version of the NDK.

File-Based API

  • The “cmake-file-api(7)” gained a new “toolchains” object kind that
    describes the compiler used for each enabled language.

Commands

  • “add_custom_command()” and “add_custom_target()” now support
    “generator expressions” in their “OUTPUT” and “BYPRODUCTS” options.

    Their “COMMAND”, “WORKING_DIRECTORY”, and “DEPENDS” options gained
    support for new generator expressions “$<COMMAND_CONFIG:…>” and
    “$<OUTPUT_CONFIG:…>” that control cross-config handling when using
    the “Ninja Multi-Config” generator.

  • The “add_custom_command()” command gained “DEPFILE” support on
    Makefile Generators.

  • The “add_library()” command previously prohibited imported object
    libraries when using potentially multi-architecture configurations.
    This mostly affected the “Xcode” generator, e.g. when targeting iOS
    or one of the other device platforms. This restriction has now been
    removed.

  • The “cmake_path()” command was added for operations on filesystem
    paths.

  • The “configure_file()” command gained “USE_SOURCE_PERMISSIONS” and
    “FILE_PERMISSIONS” options to support copying of permissions of the
    source file and using specified permissions respectively.

  • The “file(GENERATE)” command gained a “NEWLINE_STYLE” option to
    specify how newlines are handled for the generated file.

  • The “file(GENERATE)” command gained “NO_SOURCE_PERMISSIONS”,
    “USE_SOURCE_PERMISSIONS”, and “FILE_PERMISSIONS” options for
    controlling the permissions of the generated file.

  • The “install(FILES)” command “RENAME” option learned to support
    “generator expressions”.

  • The “target_include_directories()” command gained a new option
    “AFTER”.

  • The “target_sources()” command now supports targets created by the
    “add_custom_target()” command.

  • The “try_run()” command gained a “WORKING_DIRECTORY” option to set
    the working directory in which to run the compiled check executable.

Variables

  • The “CMAKE_<LANG>_BYTE_ORDER” variable was added to provide the
    target architecture byte order detected from the toolchain.

  • The “CMAKE_RUNTIME_OUTPUT_DIRECTORY”,
    “CMAKE_LIBRARY_OUTPUT_DIRECTORY”, and
    “CMAKE_ARCHIVE_OUTPUT_DIRECTORY” variables now support target-
    dependent generator expressions.

Properties

  • The “<LANG>_CLANG_TIDY” target property and the associated
    “CMAKE_<LANG>_CLANG_TIDY” variable learned to support the “OBJC” and
    “OBJCXX” languages.

  • The “EXPORT_COMPILE_COMMANDS” target property was added for the
    associated “CMAKE_EXPORT_COMPILE_COMMANDS” variable to allow for
    configuration of exporting compile commands per target.

  • The “GENERATED” source-file property is now visible from any
    directory scope, regardless of the scope in which it is set. See
    policy “CMP0118”.

  • The “UNITY_BUILD_UNIQUE_ID” target property was added to support
    generation of an identifier that is unique per source file in unity
    builds. It can help to resolve duplicate symbol problems with
    anonymous namespaces.

  • The “WIN32_EXECUTABLE” target property now works with Clang on
    Windows.

  • The “XCODE_EMBED_FRAMEWORKS” target property was added to tell the
    “Xcode” generator to embed frameworks. Aspects of the embedding can
    be customized with the “XCODE_EMBED_FRAMEWORKS_PATH”,
    “XCODE_EMBED_FRAMEWORKS_CODE_SIGN_ON_COPY”, and
    “XCODE_EMBED_FRAMEWORKS_REMOVE_HEADERS_ON_COPY” target properties.

Modules

  • The “ExternalData” module “ExternalData_Add_Target()” function
    gained a “SHOW_PROGRESS <bool>” option for controlling whether or
    not to show progress output during the build.

  • The “ExternalProject” module “ExternalProject_Add()” function gained
    a “CONFIGURE_HANDLED_BY_BUILD” option. This can be used to make
    subsequent runs of the configure step be triggered by the build step
    when an external project dependency rebuilds instead of always re-
    running the configure step in such cases.

  • The “FindBoost” module gained a “Boost_NO_WARN_NEW_VERSIONS” option
    to silence the warning about unknown dependencies for new Boost
    versions.

  • The “FindCUDAToolkit” module gained support for finding CUDA
    toolkits when “nvcc” is a symbolic link, for example due to a
    “ccache” or “colornvcc” wrapper script.

  • The “FindGDAL” module has been improved to document and mark as
    advanced its cache variables. There is a new
    “FindGDAL_SKIP_GDAL_CONFIG” variable which may be used to skip over
    the “gdal-config”-based search. Users may also set
    “GDAL_ADDITIONAL_LIBRARY_VERSIONS” to add additional versions to the
    library name search strategy.

  • The “FindIntl” module now provides an imported target.

  • The “FindOpenSSL” module learned to support a version range.

  • The “FindPython3”, “FindPython2” and “FindPython” modules gained
    options controlling how unversioned interpreter names are searched.

  • The “UseJava” module “add_jar()” command’s “GENERATE_NATIVE_HEADERS”
    feature gained options to export the generated target.

  • The “UseSWIG” module gained the capability, for Makefile and Ninja
    generators, to use the “swig” tool to generate implicit
    dependencies.

Autogen

  • The AUTOMOC feature now works with per-config sources.

CTest

  • “ctest(1)” gained a “–test-dir” option to specify the directory in
    which to look for tests.

CPack

  • “CPack” gained the “CPACK_THREADS” variable to control the number of
    threads used for parallelized operations, such as compressing the
    installer package.

  • The “CPack DEB Generator” learned a new
    “CPACK_DEBIAN_PACKAGE_SHLIBDEPS_PRIVATE_DIRS” variable to specify
    additional search directories for resolving private library
    dependencies when using “dpkg-shlibdeps”.

  • The “CPack IFW Generator” gained a new
    “CPACK_IFW_PACKAGE_WIZARD_SHOW_PAGE_LIST” variable to control
    visibility of the widget listing installer pages on the left side of
    the wizard. This feature available only since QtIFW 4.0.

  • The “CPack NSIS Generator” gained new “CPACK_NSIS_BRANDING_TEXT” and
    “CPACK_NSIS_BRANDING_TEXT_TRIM_POSITION” variables to change the
    text at the bottom of the install window and change its trim
    position

  • The “CPack NSIS Generator” now correctly handles Unicode characters.
    If you want to have a “CPACK_RESOURCE_FILE_LICENSE” with UTF-8
    characters, it needs to be encoded in UTF-8 BOM.

  • The “CPack NuGet Generator” gained options:

    • “CPACK_NUGET_PACKAGE_ICON” and
      “CPACK_NUGET_<compName>_PACKAGE_ICON” allow package icons to be
      specified by local files.

    • “CPACK_NUGET_PACKAGE_LICENSE_EXPRESSION” and
      “CPACK_NUGET_<compName>_PACKAGE_LICENSE_EXPRESSION” add support
      for specifying licenses recognized by the Software Package Data
      Exchange (SPDX).

    • “CPACK_NUGET_PACKAGE_LICENSE_FILE_NAME” and
      “CPACK_NUGET_<compName>_PACKAGE_LICENSE_FILE_NAME” allow licenses
      to be specified by local files.

    • “CPACK_NUGET_PACKAGE_LANGUAGE” and
      “CPACK_NUGET_<compName>_PACKAGE_LANGUAGE” allow the locale for a
      package to be specified, for example “en_CA”.

Deprecated and Removed Features

  • The “cmake-server(7)” mode has been removed. Clients should use the
    “cmake-file-api(7)” instead.

  • The “WriteCompilerDetectionHeader” module has been deprecated via
    policy “CMP0120”. Projects should be ported away from it.

  • The “TestBigEndian” module has been deprecated in favor of the
    “CMAKE_<LANG>_BYTE_ORDER” variable.

  • The “AddFileDependencies” module is deprecated. Port projects to use
    “set_property()” directly.

  • The “CPack NuGet Generator” deprecated some variables to reflect
    changes in the NuGet specification:

    • “CPACK_NUGET_PACKAGE_ICONURL” and
      “CPACK_NUGET_<compName>_PACKAGE_ICONURL” have been deprecated;
      replace with a reference to a local icon file.

    • “CPACK_NUGET_PACKAGE_LICENSEURL” and
      “CPACK_NUGET_<compName>_PACKAGE_LICENSEURL” have been deprecated;
      replace with a reference to the project’s license file or SPDX
      license expression.

Other Changes

  • Source file extensions must now be explicit. See policy “CMP0115”
    for details.

  • The “LANGUAGE” source file property now forces compilation as the
    specified language. See policy “CMP0119”.

  • On AIX, installation of XCOFF executables and shared libraries no
    longer requires relinking to change the runtime search path from the
    build-tree RPATH to the install-tree RPATH. CMake now edits the
    XCOFF binaries directly during installation, as has long been done
    on ELF platforms.

  • With MSVC-like compilers the value of “CMAKE_CXX_FLAGS” no longer
    contains the “/GR” flag for runtime type information by default. See
    policy “CMP0117”.

  • Ninja generators now transform the “DEPFILE” generated by an
    “add_custom_command()”. See policy “CMP0116” for details.

  • The implementation of the “ExternalProject” module was significantly
    refactored. The patch step gained support for using the terminal
    with a new “USES_TERMINAL_PATCH” keyword as a by-product of that
    work.

  • The “FetchContent” module no longer creates a separate sub-build to
    implement the content population. It now invokes the step scripts
    directly from within the main project’s configure stage. This
    significantly speeds up the configure phase when the required
    content is already populated and up-to-date.

  • The precompiled Linux binaries provided on cmake.org have changed
    their naming pattern to “cmake-$ver-linux-$arch”, where “$arch” is
    either “x86_64” or “aarch64”.

  • The precompiled Windows binaries provided on cmake.org have changed
    their naming pattern to “cmake-$ver-windows-$arch”, where “$arch” is
    either “x86_64” or “i386”.

Changes made since CMake 3.20.0-rc2:

Ben Boeckel (5):

  • FindOpenGL: handle GLX without GLVND
  • Help/guide: fix the remaining CMake install destinations
  • gitlab-ci: always upload test and release artifacts
  • gitlab-ci: allow some jobs to ignore failing tests on nightly runs
  • gitlab-ci: ignore failing tests for external IDE testing

Brad King (4):

  • gitlab-ci: update macOS jobs to use Xcode 12.4
  • Help: Document CMAKE_ANDROID_NDK_VERSION variable
  • Tests: Update RunCMake.Android for NDK r22
  • CMake 3.20.0-rc3

Haibo Huang (2):

  • Android: Detect NDK version number
  • Android: Do not use gold for ndk >= r22

Raul Tambre (2):

  • CMakeDetermineCompilerId: Test without COMPILER_ID_FLAGS if REQUIRE_SUCCESS
  • CMakeDetermineCompilerId: Fix REQUIRE_SUCCESS with multiple user flags

Robert Maynard (2):

  • HELP: Update compile-features documentation with missing compilers
  • PGI: Explicitly specify CMAKE_CXX98_STANDARD_COMPILE_OPTION