SwiftCore

SwiftCore contains core libraries that sit below the platform overlays. These include the standard library and associated runtimes, SwiftOnoneSupport, and the concurrency runtimes.

Build Instructions

Important

The standard library requires that it is built with a Swift compiler that is at least as new as the standard library sources. You will likely need to build the compiler as you would normally. In these instructions, <swiftc> is the path to your just-built Swift compiler.

Run these commands from the Runtimes/Core directory.

Build a standard library with the default configuration. This builds for the system that the command was run on, usually resulting in a static archive without optimizations applied.

cmake -B build -S . -G Ninja -DCMAKE_Swift_COMPILER=<swiftc>
cmake --build build
DESTDIR=/tmp/staging-dir cmake --install build --prefix /usr

The DESTDIR environment variable sets the staging location so that the result of the build isn't installed directly to /usr on the system performing the build.

Note

The DESTDIR environment variable is not portable to Windows. Use CMAKE_INSTALL_PREFIX or the --prefix flag to set the staging location.

To build the runtimes as dynamic libraries, pass -DBUILD_SHARED_LIBS=YES to CMake.

cmake -B build -S . -G Ninja -DBUILD_SHARED_LIBS=YES -DCMAKE_Swift_COMPILER=<swiftc>
cmake --build build

To enable semantic editing, ensure you're running CMake 3.29 or newer and enable CMAKE_EXPORT_COMPILE_COMMANDS.

cmake -B build -DCMAKE_EXPORT_COMPILE_COMMANDS=YES

Some editors will look under <source-root>/build for the generated compile_commands.json while others do not. On UNIX-like systems, run ln -s build/compile_commands.json. On Windows, creating symlinks requires administrator privileges, but can be done with CMake cmake -E create_symlink build\compile_commands.json compile_commands.json. If you do not have administrator privileges, you can copy the file from your build directory into the root directory of your sources. Note that the copied file won't be updated so you will need to copy the file each time you re-run CMake.

The compile-commands are specific to the current build configuration, so the semantic results shown in the editor match what you are currently building.

There are many more knobs for configuration. From the build directory, run ccmake to edit the build configuration to your liking.

Reproducing a Build

The knobs make it easy to build the standard library to your needs, but can make it challenging to reproduce a specific build configuration. CMake has cache files to specify how to position the knobs for a given configuration.

These caches live under cmake/caches, but can live anywhere. The following command uses the x86_64-MacOSX.cmake cache file to reproduce the Apple Intel macOS standard library build.

cmake -B build -S . -G Ninja \
    -DCMAKE_OSX_DEPLOYMENT_TARGET=15.3 \
    -DCMAKE_OSX_SYSROOT=macosx \
    -DCMAKE_Swift_COMPILER=<swiftc> \
    --toolchain cmake/caches/Vendors/Apple/Darwin.toolchain.cmake \
    -C cmake/caches/Vendors/Apple/x86_64-MacOSX.cmake
cmake --build build

Note

Variables are evaluated in order of appearance on the command line. The x86_64-MacOSX.cmake cache requires that CMAKE_OSX_DEPLOYMENT_TARGET is set before usage. Therefore, setting CMAKE_OSX_DEPLOYMENT_TARGET must come before specifying the cache or you will get an error message.