CMake 3.16 Release Notes

Changes made since CMake 3.15 include the following.

New Features

Languages

• CMake learned to support the Objective C (OBJC) and Objective C++ (OBJCXX) languages. They may be enabled via the project() and enable_language() commands. When OBJC or OBJCXX is enabled, source files with the .m or .mm, respectively, will be compiled as Objective C or C++. Otherwise they will be treated as plain C++ sources as they were before.

Compilers

• The Clang compiler is now supported on Solaris.

Platforms

• On AIX, executables using the ENABLE_EXPORTS target property now produce a linker import file with a .imp extension in addition to the executable file. Plugins (created via add_library() with the MODULE option) that use target_link_libraries() to link to the executable for its symbols are now linked using the import file. The install(TARGETS) command now installs the import file as an ARCHIVE artifact.

• On AIX, runtime linking is no longer enabled by default. CMake provides the linker enough information to resolve all symbols up front. One may manually enable runtime linking for shared libraries and/or loadable modules by adding -Wl,-G to their link flags (e.g. in the CMAKE_SHARED_LINKER_FLAGS or CMAKE_MODULE_LINKER_FLAGS variable). One may manually enable runtime linking for executables by adding -Wl,-brtl to their link flags (e.g. in the CMAKE_EXE_LINKER_FLAGS variable).

Command-Line

• cmake(1) -E now supports true and false commands, which do nothing while returning exit codes of 0 and 1, respectively.

• cmake(1) gained a --trace-redirect=<file> command line option that can be used to redirect --trace output to a file instead of stderr.

• The cmake(1) --loglevel command line option has been renamed to --log-level to make it consistent with the naming of other command line options. The --loglevel option is still supported to preserve backward compatibility.

Commands

• The add_test() command learned the option COMMAND_EXPAND_LISTS which causes lists in the COMMAND argument to be expanded, including lists created by generator expressions.

• The file() command learned a new sub-command, GET_RUNTIME_DEPENDENCIES, which allows you to recursively get the list of libraries linked by an executable or library. This sub-command is intended as a replacement for GetPrerequisites.

• The find_file(), find_library(), find_path(), find_package(), and find_program() commands have learned to check the following variables to control the default behavior for groups of search locations:

  • CMAKE_FIND_USE_PACKAGE_ROOT_PATH - Controls the default behavior of searching the <PackageName>_ROOT variables.

  • CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH - Controls the default behavior of searching the CMake-specific environment variables.

  • CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH - Controls the default behavior of searching the standard system environment variables.

  • CMAKE_FIND_USE_CMAKE_PATH - Controls the default behavior of searching the CMake-specific cache variables.

  • CMAKE_FIND_USE_CMAKE_SYSTEM_PATH - Controls the default behavior of searching the platform-specific CMake variables.

• The find_package() command has learned to check the CMAKE_FIND_USE_PACKAGE_REGISTRY variable to control the default behavior of searching the CMake user package registry and to check the CMAKE_FIND_USE_SYSTEM_PACKAGE_REGISTRY variable to control the default behavior of searching the CMake system package registry.

• The message() command learned indentation control with the new CMAKE_MESSAGE_INDENT variable.

• The target_precompile_headers() command was added to specify a list of headers to precompile for faster compilation times.

Variables

• The CMAKE_CUDA_RESOLVE_DEVICE_SYMBOLS variable has been introduced to optionally initialize the CUDA_RESOLVE_DEVICE_SYMBOLS target property.

• The CMAKE_ECLIPSE_RESOURCE_ENCODING variable was added to specify the resource encoding for the the Eclipse CDT4 extra generator.

• The CMAKE_UNITY_BUILD variable was added to initialize the UNITY_BUILD target property to tell generators to batch include source files for faster compilation times.

Properties

• The BUILD_RPATH and INSTALL_RPATH target properties now support generator expressions.

• The INSTALL_REMOVE_ENVIRONMENT_RPATH target property was added to remove compiler-defined RPATH entries from a target. This property is initialized by the CMAKE_INSTALL_REMOVE_ENVIRONMENT_RPATH variable.

• The PRECOMPILE_HEADERS target property was added to specify a list of headers to precompile for faster compilation times. Set it using the target_precompile_headers() command.

• The UNITY_BUILD target property was added to tell generators to batch include source files for faster compilation times.

• The VS_CONFIGURATION_TYPE target property now supports generator expressions.

• The VS_DPI_AWARE target property was added to tell Visual Studio Generators to set the EnableDpiAwareness property in .vcxproj files.

• The XCODE_SCHEME_DEBUG_DOCUMENT_VERSIONING target property was added to tell the Xcode generator to set the value of the Allow debugging when using document Versions Browser schema option.

Modules

• The FindDoxygen module doxygen_add_docs() command gained a new USE_STAMP_FILE option. When this option present, the custom target created by the command will only re-run Doxygen if any of the source files have changed since the last successful run.

• The FindGnuTLS module now provides an imported target.

• The FindPackageHandleStandardArgs module find_package_handle_standard_args() command gained a new REASON_FAILURE_MESSAGE option to specify a message giving the reason for the failure.

• The FindPkgConfig module pkg_search_module() macro now defines a <prefix>_MODULE_NAME result variable containing the first matching module name.

• The FindPython3 and FindPython modules gained options to control which ABIs will be searched.

• The FindPython3, FindPython2, and FindPython modules now support direct specification of artifacts via cache entries.

Autogen

• When using AUTOMOC, the new CMAKE_AUTOMOC_PATH_PREFIX variable or AUTOMOC_PATH_PREFIX target property may be enabled to generate the -p path prefix option for moc. This ensures that moc output files are identical on different build setups (given, that the headers compiled by moc are in an include directory). Also it ensures that moc output files will compile correctly when the source and/or build directory is a symbolic link.

CTest

• ctest(1) now has the ability to schedule tests based on resource requirements for each test. See Resource Allocation for details.

• A new test property, SKIP_REGULAR_EXPRESSION, has been added. This property is similar to FAIL_REGULAR_EXPRESSION and PASS_REGULAR_EXPRESSION, but with the same meaning as SKIP_RETURN_CODE. This is useful, for example, in cases where the user has no control over the return code of the test. For example, in Catch2, the return value is the number of assertion failed, therefore it is impossible to use it for SKIP_RETURN_CODE.

CPack

• cpack(1) learned support for multiple configurations for -C option.

• The CPack DEB Generator is now able to format generic text (usually used as the description for multiple CPack generators) according to the Debian Policy Manual. See the CPACK_PACKAGE_DESCRIPTION_FILE and CPACK_DEBIAN_<COMPONENT>_DESCRIPTION variables.

• The CPack Archive Generator learned to generate .tar.zst packages with Zstandard compression.

Deprecated and Removed Features

• An explicit deprecation diagnostic was added for policy CMP0067 (CMP0066 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.

• The CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY variable has been deprecated. Use the CMAKE_FIND_USE_PACKAGE_REGISTRY variable instead.

• The GetPrerequisites module has been deprecated, as it has been superseded by file(GET_RUNTIME_DEPENDENCIES).

• The CPACK_INSTALL_SCRIPT variable has been deprecated in favor of the new, more accurately named CPACK_INSTALL_SCRIPTS variable.

Other Changes

• The cmake(1) -C <initial-cache> option now evaluates the initial cache script with CMAKE_SOURCE_DIR and CMAKE_BINARY_DIR set to the top-level source and build trees.

• The cmake(1) -E remove_directory command-line tool, when given the path to a symlink to a directory, now removes just the symlink. It no longer removes content of the linked directory.

• The ctest(1) --build-makeprogram command-line option now specifies the make program used when configuring a project with the Ninja generator or the Makefile Generators.

• The ExternalProject module ExternalProject_Add() command has been updated so that GIT_SUBMODULES "" initializes no submodules. See policy CMP0097.

• The FindGTest module has been updated to recognize MSVC build trees generated by GTest 1.8.1.

• The project() command no longer strips leading zeros in version components. See policy CMP0096.

• The Qt Compressed Help file is now named CMake.qch, which no longer contains the release version in the file name. When CMake is upgraded in-place, the name and location of this file will remain constant. Tools such as IDEs, help viewers, etc. should now be able to refer to this file at a fixed location that remains valid across CMake upgrades.

• RPATH entries are properly escaped in the generated CMake scripts used for installation. See policy CMP0095.

• When using CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS on Windows the auto-generated exports are now updated only when the object files providing the symbols are updated.

Updates

Changes made since CMake 3.16.0 include the following.

3.16.2

• CMake 3.16.0 and 3.16.1 processed .hh files with AUTOMOC. This was a behavior change from CMake 3.15 and below that can break existing projects, so it has been reverted as of 3.16.2.

3.16.5

• The FindPython, FindPython2, and FindPython3 modules no longer create cache entries for Python{,2,3}_LIBRARY_RELEASE and Python{,2,3}_LIBRARY_DEBUG. Those values are always computed from other results and so should not be cached. The entries were created by CMake 3.16.0 through 3.16.4 but were always FORCE-set and could not be meaningfully edited by users.

  Additionally, the modules no longer expose their internal _Python* cache entries publicly. CMake 3.16.0 through 3.16.4 accidentally made them visible as advanced cache entries.

3.16.7

• Selection of the Objective C or C++ compiler now considers the CC or CXX environment variable if the OBJC or OBJCXX environment variable is not set.

• The FindPkgConfig module now extracts include directories prefixed with -isystem into the *_INCLUDE_DIRS variables and INTERFACE_INCLUDE_DIRECTORIES target properties. Previously they would be places in *_CFLAGS_OTHER variables and INTERFACE_COMPILE_OPTIONS target properties.

3.16.9

• The default value of CMAKE_AUTOMOC_PATH_PREFIX was changed to OFF because this feature can break existing projects that have identically named header files in different include directories. This restores compatibility with behavior of CMake 3.15 and below.