CMake 3.15 Release Notes

Changes made since CMake 3.14 include the following.

New Features



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

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


  • 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).


  • 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.


  • 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 <prefix>_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.




  • 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 <library_name> for python language or -dllimport <library_name> 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.

  • The $<CUDA_COMPILER_ID:...> and $<CUDA_COMPILER_VERSION:...> generator expressions were added.

  • The $<COMPILE_LANG_AND_ID:...> generator expression was introduced to allow specification of compile options for target files based on the CMAKE_<LANG>_COMPILER_ID and LANGUAGE of each source file.

  • A $<FILTER:list,INCLUDE|EXCLUDE,regex> generator expression has been added.

  • A $<REMOVE_DUPLICATES:list> generator expression has been added.

  • The $<SHELL_PATH:...> generator expression gained support for a list of paths.

  • New $<TARGET_FILE*> generator expressions were added to retrieve the prefix, base name, and suffix of the file names of various artifacts:








  • The $<TARGET_OBJECTS:...> generator expression is now supported on SHARED, STATIC, MODULE libraries and executables.


  • 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.


Deprecated and Removed Features

Other Changes

  • If a feature specified by target_compile_features() is available in the compiler’s default standard level, CMake 3.14 and below incorrectly added unnecessary -std= flags that could lower the standard level. This bug has been fixed in CMake 3.15. This behavior change may expose bugs in existing projects that were relying on undocumented implementation details. Specifying compile features only ensures that the compiler runs in a mode that has those features, not that any specific standard level is used or explicit -std= flag passed.

  • 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_<LANG>_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.


Changes made since CMake 3.15.0 include the following.


  • In CMake 3.15.0 support for the GNU-like Clang compiler targeting the MSVC ABI implemented CMAKE_CXX_STANDARD values 98 and 11 using the corresponding -std= flags. However, these modes do not work with the MSVC standard library. Therefore CMake 3.15.1 passes C++14 standard flags even for C++98 and C++11. This is consistent with MSVC itself which always runs in a mode aware of C++14.

  • Preliminary Swift support added in 3.15.0 has been updated.



  • CrayPrgEnv compiler wrapper support has been updated for the 19.06 release of the Cray Programming Environment for which the default linking mode on XC Cray systems is now dynamic instead of static.


  • In CMake 3.15.0 through 3.15.3, the EXCLUDE_FROM_ALL directory property was regressed from pre-3.14 behavior and caused targets within the directory to be excluded even from its own “all”. This has been fixed. The bug also existed in 3.14.0 through 3.14.6 and is fixed in 3.14.7.