# CMake 3.19 Release Notes

Changes made since CMake 3.18 include the following.

## New Features

### Presets

- `cmake(1)` and `cmake-gui(1)` now recognize `CMakePresets.json` and `CMakeUserPresets.json` files (see `cmake-presets(7)`).

### Generators

- The `Xcode` generator now uses the Xcode "new build system" when generating for Xcode 12.0 or higher. See the `CMAKE_XCODE_BUILD_SYSTEM` variable. One may use `-T buildsystem=1` to switch to the legacy build system.

- The `Xcode` generator gained support for linking libraries and frameworks via the Link Binaries With Libraries build phase instead of always by embedding linker flags directly. This behavior is controlled by a new `XCODE_LINK_BUILD_PHASE_MODE` target property, which is initialized by a new `CMAKE_XCODE_LINK_BUILD_PHASE_MODE` variable.

- The Visual Studio Generators for VS 2015 and above gained support for the Visual Studio Tools for Android. One may now set `CMAKE_SYSTEM_NAME` to `Android` to generate `.vcxproj` files for the Android tools.

### Languages

- CMake learned to support `ISPC` as a first-class language that can be enabled via the `project()` and `enable_language()` commands. `ISPC` is currently supported by the Makefile Generators and the `Ninja` generator on Linux, macOS, and Windows using the Intel ISPC compiler.

- `CUDA` language support for Clang now includes:

  - separable compilation (`CUDA_SEPARABLE_COMPILATION`), and

  - finding scattered toolkit installations when cross-compiling.

- `CUDA` language support now works on QNX.

### Platforms

- Apple Silicon is now supported (since CMake 3.19.2):

  - The `CMAKE_HOST_SYSTEM_PROCESSOR` is selected using `uname -m`. Since this may vary based on CMake's own architecture and that of the invoking process tree, the `CMAKE_APPLE_SILICON_PROCESSOR` variable or `CMAKE_APPLE_SILICON_PROCESSOR` environment variable may be set to specify a host architecture explicitly.

  - If `CMAKE_OSX_ARCHITECTURES` is not set, CMake adds explicit flags to tell the compiler to build for the `CMAKE_HOST_SYSTEM_PROCESSOR` so the toolchain does not have to guess based on the process tree's architecture.

### File-Based API

- The `cmake-file-api(7)` "codemodel" version 2 `version` field has been updated to 2.2.

- The `cmake-file-api(7)` "codemodel" version 2 "target" object gained a new `languageStandard` field in the `compileGroups` objects.

### Command-Line

- The `cmake(1)` command-line tool's `--install` mode gained a `--default-directory-permissions` option.

- `cmake(1)` gained a `-E create_hardlink` command-line tool that can be used to create hardlinks between files.

### GUI

- The `CMake GUI` now has an environment variable editor.

### Commands

- The `add_test()` command now (officially) supports whitespace and other special characters in the name for the test it creates. See policy `CMP0110`.

- The `cmake_language()` command gained a `DEFER` mode to schedule command calls to occur at the end of processing a directory.

- The `configure_file()` command gained a `NO_SOURCE_PERMISSIONS` option to suppress copying the input file's permissions to the output file.

- The `execute_process()` command gained a `COMMAND_ERROR_IS_FATAL` option to specify a fatal error.

- The `file(ARCHIVE_CREATE)` command gained a `COMPRESSION_LEVEL` option to specify the compression level.

- The `file(CHMOD)` and `file(CHMOD_RECURSE)` subcommands were added to set permissions of files and directories.

- The `file(DOWNLOAD)` command `<file>` argument is now optional. If it is not specified, the file is not saved.

- The `file(GENERATE)` command gained a new `TARGET` keyword to support resolving target-dependent generator expressions.

- The `file()` command gained a new `REAL_PATH` sub-command to compute a path with symlinks resolved.

- The `find_package()` command learned to handle a version range.

- The `separate_arguments()` command gained a new `PROGRAM` option. It allows the arguments to be treated as a program invocation and will resolve the executable to a full path if it can be found.

- The `DIRECTORY` option of the `set_property()`, `get_property()`, and `get_directory_property()` commands now accepts references to binary directory paths, such as the value of `CMAKE_CURRENT_BINARY_DIR`.

- The `string()` command gained a set of new `JSON` sub commands that provide JSON parsing capabilities.

### Variables

- The `CMAKE_CLANG_VFS_OVERLAY` variable was added to tell Clang to use a VFS overlay to support the Windows SDK when cross-compiling from hosts with case-sensitive filesystems.

- The `CMAKE_MFC_FLAG` variable now supports generator expressions.

- The `CMAKE_OPTIMIZE_DEPENDENCIES` variable was added to initialize the new `OPTIMIZE_DEPENDENCIES` target property and avoid unnecessarily building dependencies for a static library.

- The `CMAKE_PCH_INSTANTIATE_TEMPLATES` variable was added to initialize the new `PCH_INSTANTIATE_TEMPLATES` target property.

- The `CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION_MAXIMUM` variable was added to tell the Visual Studio Generators what maximum version of the Windows SDK to choose.

### Properties

- The `EXCLUDE_FROM_ALL` target property now supports `generator expressions`.

- The `OPTIMIZE_DEPENDENCIES` target property was added to avoid unnecessarily building dependencies for a static library.

- The `PCH_INSTANTIATE_TEMPLATES` target property was added to enable template instantiation in the precompiled header. This is enabled by default and may significantly improve compile times. Currently only supported for Clang (version 11 or later).

- The `WIN32_EXECUTABLE` target property now supports `generator expressions`.

### Modules

- The `CheckCompilerFlag` module has been added to generalize `CheckCCompilerFlag` and `CheckCXXCompilerFlag` to more languages. It also supports the `CUDA` and `ISPC` languages.

- The `CheckLinkerFlag` module now supports the `CUDA` language.

- The `CheckSourceCompiles` module has been added to generalize `CheckCSourceCompiles` and `CheckCXXSourceCompiles` to more languages. It also supports the `CUDA` and `ISPC` languages.

- The `CheckSourceRuns` module has been added to generalize `CheckCSourceRuns` and `CheckCXXSourceRuns` to more languages. It also supports the `CUDA` language.

- The `CMakePackageConfigHelpers` module gained support for version ranges.

- The `FindCUDAToolkit` module gained support for finding CUDA toolkits that do not contain `nvcc`, as well as for finding scattered toolkit installations when cross-compiling.

- The `FindPackageHandleStandardArgs` module learned to handle version ranges. It also gained the `find_package_check_version()` command to check the validity of a version against version-related arguments of `find_package()` command.

- The `FindPython3`, `FindPython2` and `FindPython` modules gained the ability to handle a version range.

- The `FindPython3`, `FindPython2` and `FindPython` modules provide, respectively, the variable `Python3_LINK_OPTIONS`, `Python2_LINK_OPTIONS` and `Python_LINK_OPTIONS` for link options.

- The `FindSDL` module now provides:

  - An imported target `SDL::SDL`.

  - Result variables `SDL_LIBRARIES` and `SDL_INCLUDE_DIRS`.

  - Version variables `SDL_VERSION`, `SDL_VERSION_MAJOR`, `SDL_VERSION_MINOR`, and `SDL_VERSION_PATCH`.

- The `FindSWIG` module gained the ability to handle a version range.

- The `FindTIFF` module gained a `CXX` component to find the `tiffxx` library containing C++ bindings.

- The `FindVulkan` module now provides a `Vulkan::glslc` imported target and associated `Vulkan_GLSLC_EXECUTABLE` variable which contain the path to the GLSL SPIR-V compiler.

- The `UseSWIG` module gained support for new source file properties `OUTPUT_DIR` and `OUTFILE_DIR` to manage output directories on a per-source basis.

### CTest

- `ctest(1)` now supports the CUDA `compute-sanitizer` checker (previously known as `cuda-memcheck`) as the `CTEST_MEMORYCHECK_COMMAND`. The different tools (`memcheck`, `racecheck`, `synccheck` and `initcheck`) supported by `compute-sanitizer` can be selected by adding appropriate flags to the `CTEST_MEMORYCHECK_COMMAND_OPTIONS` variable. The default flags are `--tool memcheck --leak-check full`.

### CPack

- CPack gained the `CPACK_PRE_BUILD_SCRIPTS`, `CPACK_POST_BUILD_SCRIPTS`, and `CPACK_PACKAGE_FILES` variables.

- The `CPack External Generator` gained the `CPACK_EXTERNAL_BUILT_PACKAGES` variable.

- The `CPack WIX Generator` gained a `CPACK_WIX_CUSTOM_XMLNS` option to specify custom XML namespaces.

### Other

- Interface Libraries may now have source files added via `add_library()` or `target_sources()`. Those with sources will be generated as part of the build system.

## Deprecated and Removed Features

- Compatibility with versions of CMake older than 2.8.12 is now deprecated and will be removed from a future version. Calls to `cmake_minimum_required()` or `cmake_policy()` that set the policy version to an older value now issue a deprecation diagnostic.

- An explicit deprecation diagnostic was added for policy `CMP0071` (`CMP0071` 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.

- macOS SDKs older than 10.5 are no longer supported.

- `cmake-gui(1)` now requires Qt5. Support for compiling with Qt4 has been removed.

- The `cmake(1)` command-line option `--warn-unused-vars` has been removed and is now silently ignored. The option has not worked correctly since CMake 3.3.

## Documentation

The following guides have been added:

- `IDE Integration Guide`

- `Importing and Exporting Guide`

## Other Changes

- Building for macOS will now use the latest SDK available on the system, unless the user has explicitly chosen a SDK using `CMAKE_OSX_SYSROOT`. The deployment target or system macOS version will not affect the choice of SDK.

- The `CMAKE_<LANG>_COMPILER` variable may now be used to store "mandatory" compiler flags like the `CC` and other environment variables.

- The `CMAKE_<LANG>_FLAGS_INIT` variable will now be considered during the compiler identification check if other sources like `CMAKE_<LANG>_FLAGS` or `CFLAGS` are not set.

- The `find_program()` command now requires permission to execute but not to read the file found. See policy `CMP0109`.

- An imported target missing its location property fails during generation if the location is used. See policy `CMP0111`.

- The following target-based generator expressions that query for directory or file name components no longer add a dependency on the evaluated target. See policy `CMP0112`.

  - `TARGET_FILE_DIR`

  - `TARGET_LINKER_FILE_BASE_NAME`

  - `TARGET_LINKER_FILE_NAME`

  - `TARGET_LINKER_FILE_DIR`

  - `TARGET_SONAME_FILE_NAME`

  - `TARGET_SONAME_FILE_DIR`

  - `TARGET_PDB_FILE_NAME`

  - `TARGET_PDB_FILE_DIR`

  - `TARGET_BUNDLE_DIR`

  - `TARGET_BUNDLE_CONTENT_DIR`

- Makefile Generators no longer repeat custom commands from target dependencies. See policy `CMP0113`.

- The `ExternalProject` module handling of step target dependencies has been revised. See policy `CMP0114`.

- The `OSX_ARCHITECTURES` target property is now respected for the `ASM` language.

- If `CUDA` compiler detection fails with user-specified `CMAKE_CUDA_ARCHITECTURES` or `CMAKE_CUDA_HOST_COMPILER`, an error is raised.

## Updates

Changes made since CMake 3.19.0 include the following.

### 3.19.1

- CMake 3.19.0 compiles source files with the `LANGUAGE` property by passing an explicit language flag such as `-x c`. This is consistent with the property's documented meaning that the source file is written in the specified language. However, it can break projects that were using the property only to cause the specified language's compiler to be used. This has been reverted to restore behavior from CMake 3.18 and below.

- CUDA 11.1 support for Clang.

### 3.19.2

- The precompiled macOS binary provided on `cmake.org` is now a universal binary with `x86_64` and `arm64` architectures. It requires macOS 10.10 or newer. The package file naming pattern has been changed from `cmake-$ver-Darwin-x86_64` to `cmake-$ver-macos-universal`.

- Apple Silicon host architecture selection support was updated. CMake 3.19.0 and 3.19.1 always chose `arm64` as the host architecture. CMake 3.19.2 returns to using `uname -m` as CMake 3.18 and below did. Since this may vary based on CMake's own architecture and that of the invoking process tree, the `CMAKE_APPLE_SILICON_PROCESSOR` variable or `CMAKE_APPLE_SILICON_PROCESSOR` environment variable may be set to specify a host architecture explicitly.

- The `CMAKE_ISPC_HEADER_SUFFIX` variable and corresponding `ISPC_HEADER_SUFFIX` target property were added to control the header suffix used by `ISPC` compiler generated headers.

### 3.19.3

- A precompiled Linux `aarch64` binary is now provided on `cmake.org`.

- Two precompiled macOS binaries are now provided on `cmake.org`:

  - The naming pattern `cmake-$ver-macos-universal` is a universal binary with `x86_64` and `arm64` architectures. It requires macOS 10.13 or newer.

  - The naming pattern `cmake-$ver-macos10.10-universal` is a universal binary with `x86_64` and `arm64` architectures. It requires macOS 10.10 or newer.

### 3.19.4

- The `CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION_MAXIMUM` variable introduced in 3.19.0 previously worked only with the `Visual Studio 14 2015` generator. It has now been fixed to work with Visual Studio Generators for later VS versions too.

### 3.19.5

- When `IOS_INSTALL_COMBINED` is enabled and the `Xcode` generator is used, it is now possible to initiate an install or package creation by running `cmake --install` or `cpack` from the command line. When using the Xcode new build system, these are the only supported methods due to a limitation of Xcode. Initiating these operations by building the `install` or `package` targets in Xcode is only supported when using the legacy build system.

- The framework handling introduced in 3.19.0 as part of supporting Xcode's Link Binaries With Libraries build phase broke the ability to switch between device and simulator builds without reconfiguring. That capability has now been restored.

### 3.19.6

- The `cmake-presets(7)` feature no longer allows comments in `CMakePresets.json` or `CMakeUserPresets.json` files. This was mistakenly allowed by the implementation in CMake 3.19.0 through CMake 3.19.5, and was not documented.

### 3.19.7

- With Visual Studio Generators for VS 2017 and higher, the `CMAKE_GENERATOR_TOOLSET` field `version=` now accepts three-component MSVC toolset versions such as `14.28.29910`. See the `CMAKE_VS_PLATFORM_TOOLSET_VERSION` variable.