modern-cmake/chapters/intro/newcmake.md

What's new in in CMake

This is an abbreviated version of the CMake changlog with just the highlights for authors. Names for each release are arbitrarily picked by the author.

CMake 3.0 : Interface libraries

There were a ton of additions to this version of CMake, primarily to fill out the target interface. Some bits of needed functionality were missed and implemented in CMake 3.1 instead.

• Initially released June 10, 2014
• New documentation
• INTERFACE libraries
• Project VERSION support
• Exporting build trees easily
• Bracket arguments and comments available (not widely used)
• Lots of improvements

CMake 3.1 : C++11 and compile features

This is the first release of CMake to support C++11. Combined with fixes to the new features of CMake 3.0, this is currently a common minimum version of CMake for libraries that want to support old CMake builds.

• Initially released December 17, 2014
• C++11 Support
• Compile features support
• Sources can be added later with target_sources
• Better support for generator expressions and INTERFACE targets

CMake 3.2 : UTF8

This is a smaller release, with mostly small features and fixes. Internal changes, like better Windows and UTF8 support, were the focus.

• Initially released March 11, 2015
• continue() inside loops
• File and directory locks added

CMake 3.3 : if IN_LIST

This is notable for the useful IN_LIST option for if, but it also added better library search using $PATH (See CMake 3.6), dependencies for INTERFACE libraries, and several other useful improvements. The addition of a COMPILE_LANGUAGE generator expression would prove very useful in the future as more languages are added. Makefiles now produce better output in parallel.

• Initially released July 23, 2015
• IN_LIST added to if
• *_INCLUDE_WHAT_YOU_USE property added
• COMPILE_LANGUAGE generator expression (limited support in some generators)

CMake 3.4 : Swift & CCache

This release adds lots of useful tools, support for the Swift language, and the usual improvements. It also started supporting compiler launchers, like CCache.

• Initially released November 12, 2015
• Added Swift language
• Added BASE_DIR to get_filename_component
• if(TEST ...) added
• string(APPEND ...) added
• CMAKE_*_COMPILER_LAUNCHER added for make and ninja
• TARGET_MESSAGES allow makefiles to print messages after target is completed
• Imported targets are beginning to show up in the official Find*.cmake files

CMake 3.5 : ARM

This release expanded CMake to more platforms, and make warnings easier to control from the command line.

• Initially released March 8, 2016
• Multiple input files supported for several of the cmake -E commands.
• cmake_parse_arguments now builtin
• Boost, GTest, and more now support imported targets
• ARMCC now supported, better support for iOS
• XCode backslash fix

CMake 3.6 : Clang-Tidy

This release added Clang-Tidy support, along with more utilities and improvements. It also removed the search of $PATH on Unix systems due to problems, instead users should use $CMAKE_PREFIX_PATH.

• Initially released July 7, 2016
• EXCLUDE_FROM_ALL for install
• list(FILTER added
• CMAKE_*_STANDARD_INCLUDE_DIRECTORIES and CMAKE_*_STANDARD_LIBRARIES added for toolchains
• Try-compile improvements
• *_CLANG_TIDY property added
• External projects can now be shallow clones, and other improvements

CMake 3.7 : Android & CMake Server

You can now cross-compile to Android. Useful new if statement options really help clarify code. And the new server mode was supposed to improve integration with IDEs (but is being replaced by a different system in CMake 3.14+). Support for the VIM editor was also improved.

• Initially released November 11, 2016
• PARSE_ARGV mode for cmake_parse_arguments
• Better 32-bit support on 64-bit machines
• Lots of useful new if comparisons, like VERSION_GREATER_EQUAL (really, why did it take this long?)
• LINK_WHAT_YOU_USE added
• Lots of custom properties related to files and directories
• CMake Server added
• Added --trace-source="filename" to monitor certain files only

CMake 3.8 : C# & CUDA

This adds CUDA as a language, as well as cxx_std_11 as a compiler meta-feature. The new generator expression could be really useful if you can require CMake 3.8+!

• Initially released April 10, 2017
• Native support for C# as a language
• Native support for CUDA as a language
• Meta features cxx_std_11 (and 14, 17) added
• try_compile has better language support
• BUILD_RPATH property added
• COMPILE_FLAGS now supports generator expression
• *_CPPLINT added
• $<IF:cond,true-value,false-value> added (wow!)
• source_group(TREE added (finally allowing IDEs to reflect the project folder structure!)

CMake 3.9 : IPO

Lots of fixes to CUDA support went into this release, including PTX support and MSVC generators. Interprocedural Optimizations are now supported properly. Even more modules provide imported targets, including MPI.

• Initially released July 18, 2017
• CUDA supported for Windows
• Better object library support in several situations
• DESCRIPTION added to project
• separate_arguments gets NATIVE_COMMAND
• INTERPROCEDURAL_OPTIMIZATION enforced (and CMAKE_* initializer added, CheckIPOSupported added, Clang and GCC support)
• New GoogleTest module
• FindDoxygen drastically improved

CMake 3.10 : CppCheck

CMake now is built with C++11 compilers. Lots of useful improvements help write cleaner code.

• Initially released November 20, 2017
• Support for flang Fortran compiler
• Compiler launcher added to CUDA
• Indented #cmakedefines now supported for configure_file
• include_guard() added to ensure a file gets included only once
• string(PREPEND added
• *_CPPCHECK property added
• LABELS added to directories
• FindMPI vastly expanded
• FindOpenMP improved
• Dynamic test discovery for GoogleTest

CMake 3.11 : Faster & IMPORTED INTERFACE

This release is supposed to be much faster. You can also finally directly add INTERFACE targets to IMPORTED libraries (the internal Find*.cmake scripts should become much cleaner eventually).

• Initially released March 28, 2018
• Fortran supports compiler launchers
• Xcode and Visual Studio support COMPILE_LANGUAGE generator expressions finally
• You can now add INTERFACE targets directly to IMPORTED INTERFACE libraries (Wow!)
• Source file properties have been expanded
• FetchContent module now allows downloads to happen at configure time (Wow)

CMake 3.12 : Version ranges and CONFIGURE_DEPENDS

Very powerful release, containing lots of smaller long-requested features. One of the smaller but immediately noticeable changes is the addition of version ranges; you can now set both the minimum and maximum known CMake version easily. You can also set CONFIGURE_DEPENDS on a GLOBed set of files, and the build system will check those files and rerun if needed! You can use the general PackageName_ROOT for all find_package searches. Lots of additions to strings and lists, module updates, shiny new Python find module (2 and 3 versions too), and many more.

• Initially released July 17, 2018
• Support for cmake_minimum_required ranges (backward compatible)
• Support for -j,--parallel in --build mode (passed on to build tool)
• Support for SHELL: strings in compile options (not deduplicated)
• New FindPython module
• string(JOIN and list(JOIN, and list(TRANSFORM
• file(TOUCH and file(GLOB CONFIGURE_DEPENDS
• C++20 support
• CUDA as a language improvements: CUDA 7 and 7.5 now supported
• Support for OpenMP on macOS (command line only)
• Several new properties and property initializers
• CPack finally reads CMAKE_PROJECT_VERSION variables

CMake 3.13 : Linking control

You can now make symbolic links on Windows! Lots of new functions that fill out the popular requests for CMake, such as add_link_options, target_link_directories, and target_link_options. You can now do quite a bit more modification to targets outside of the source directory, for better file separation. And, target_sources finally handles relative paths properly (policy 76).

• Initially released November 20, 2018
• New ctest --progress option for live output
• target_link_options and add_link_options added
• target_link_directories added
• Symbolic link creation, -E create_symlink, supported on Windows
• IPO supported on Windows
• You can use -S and -B for source and build directories
• target_link_libraries and install work outside the current target directory
• STATIC_LIBRARY_OPTIONS property added
• target_sources is now relative to the current source directory (CMP0076)
• If you use Xcode, you now can experimentally set schema fields

CMake 3.14 : File utilities (AKA CMake π)

This release has lots of small cleanups, including several utilities for files. Generator expressions work in a few more places, and list handling is better with empty variables. Quite a few more find packages produce targets. The new Visual Studio 16 2019 generator is a bit different than older versions. Windows XP and Vista support has been dropped.

• Initially released March 14, 2019
• The cmake --build command gained -v/--verbose, to use verbose builds if your build tool supports it
• The FILE command gained CREATE_LINK, READ_SYMLINK, and SIZE
• «command:get_filename_component» gained LAST_EXT and NAME_WLE to access just the last extension on a file, which would get .zip on a file such as version.1.2.zip (very handy!)
• You can see if a variable is defined in the CACHE with DEFINED CACHE{VAR} in an «command:if» statement.
• BUILD_RPATH_USE_ORIGIN and CMake version were added to improve handling of RPath in the build directory.
• The CMake server mode is now being replaced with a file API, starting in this release. Will affect IDEs in the long run.

CMake 3.15 : CLI upgrade

This release has many smaller polishing changes, include several of improvements to the CMake command line, such as control over the default generator through environment variables (so now it's easy to change the default generator to Ninja). Multiple targets are supported in --build mode, and --install mode added. CMake finally supports multiple levels of logging. Generator expressions gained a few handy tools. The still very new FindPython module continues to improve, and FindBoost is now more inline with Boost 1.70's new CONFIG module. export(PACKAGE) has drastically changed; it now no longer touches $HOME/.cmake by default (if CMake Minimum version is 3.15 or higher), and requires an extra step if a user wants to use it. This is generally less surprising.

• Initially released July 17, 2019
• «envvar:CMAKE_GENERATOR» environment variable added to control default generator
• Multiple target support in build mode, cmake . --build --target a b
• Shortcut -t for --target
• Install support, cmake . --install, does not invoke the build system
• Support for --loglevel and NOTICE, VERBOSE, DEBUG, and TRACE for message
• The «command:list» command gained PREPEND, POP_FRONT, and POP_BACK
• «command:execute_process» gained COMMAND_ECHO option («variable:CMAKE_EXECUTE_PROCESS_COMMAND_ECHO») allows you to automatically echo commands before running them
• Several Ninja improvements, include SWIFT language support
• Compiler and list improvements to generator expressions

CMake 3.16 : Unity builds

A new unity build mode was added, allowing source files to be merged into a single build file. Support for precompiled headers (possibly preparing for C++20 modules, perhaps?) was added. Lots of other smaller fixes were implemented, especially to newer features, such as to FindPython, FindDoxygen, and others.

• Initially released November 26, 2019
• Added support for Objective C and Objective C++ languages
• Support for precompiling headers, with target_precompile_headers
• Support for "Unity" or "Jumbo" builds (merging source files) with «variable:CMAKE_UNITY_BUILD»
• CTest: Can now skip based on regex, expand lists
• Several new features to control RPath.
• Generator expressions work in more places, like build and install paths
• Find locations can now be explicitly controlled through new variables

CMake 3.17 : More CUDA

A FindCUDAToolkit was finally added, which allows finding and using the CUDA toolkit without enabling the CUDA language! CUDA now is a bit more configurable, such as linking to shared libraries. Quite a bit more polish in the expected areas, as well, like FindPython. Finally, you can now iterate over multiple lists at a time.

• Initially released March 20, 2020
• CUDA_RUNTIME_LIBRARY can finally be set to Shared!
• FindCUDAToolkit finally added
• cmake -E rm replaces older remove commands
• CUDA has meta features like cuda_std_03, etc.
• You can track the searches for packages with --debug-find
• ExternalProject can now disable recursive checkouts
• FindPython better integration with Conda
• DEPRECATION can be applied to targets
• CMake gained a rm command
• Several new environment variables
• foreach can now do ZIP_LISTS (multiple lists at a time)

CMake 3.18 : CUDA with Clang

CUDA now supports Clang (without separable compilation). A new CUDA_ARCHITECTURES property was implemented to better support targeting CUDA hardware. A new cmake_language command supports calling cmake commands and expressions from strings. Lots of other meta changes that could make new designs available; calling functions by variable, evaluating arbitrary CMake by string, and configure files directly from strings. Many other nice tiny features and papercut fixes are sprinkled throughout, a small selection is below.

• Initially released July 15, 2020
• cmake can cat files together now
• New profiling mode for cmake
• cmake_language with CALL and EVAL
• export requires APPEND if used multiple times (in CMake language level 3.18+)
• You can archive directly from file()
• file(CONFIGURE is a nicer from of configure_file if you already have a string to produce
• Other find_* commands gain find_package's REQUIRED flag
• NATURAL sorting in list(SORT added
• More options for handling properties with DIRECTORY scope
• CUDA_ARCHITECTURES was added
• New LINK_LANGUAGE generator expressions (DEVICE/HOST versions too)
• Source can be a subdirectory for FetchContent