README.md
Swift Programming Language
| Architecture | Master | Package | |
|---|---|---|---|
| macOS | x86_64 | ||
| Ubuntu 16.04 | x86_64 | ||
| Ubuntu 18.04 | x86_64 |
Swift Community-Hosted CI Platforms
| OS | Architecture | Build |
|---|---|---|
| Ubuntu 16.04 | PPC64LE | |
| Ubuntu 16.04 | AArch64 | |
| Android | ARMv7 | |
| Android | AArch64 | |
| Windows 2019 | x86_64 |
Swift TensorFlow Community-Hosted CI Platforms
| OS | Architecture | Build |
|---|---|---|
| Ubuntu 16.04 | x86_64 | |
| macOS 10.13 | x86_64 | |
| Ubuntu 16.04 (GPU) | x86_64 |
Welcome to Swift
Swift is a high-performance system programming language. It has a clean and modern syntax, offers seamless access to existing C and Objective-C code and frameworks, and is memory safe by default.
Although inspired by Objective-C and many other languages, Swift is not itself a C-derived language. As a complete and independent language, Swift packages core features like flow control, data structures, and functions, with high-level constructs like objects, protocols, closures, and generics. Swift embraces modules, eliminating the need for headers and the code duplication they entail.
To learn more about the programming language, visit swift.org.
Contributing to Swift
Contributions to Swift are welcomed and encouraged! Please see the Contributing to Swift guide.
To be a truly great community, Swift.org needs to welcome developers from all walks of life, with different backgrounds, and with a wide range of experience. A diverse and friendly community will have more great ideas, more unique perspectives, and produce more great code. We will work diligently to make the Swift community welcoming to everyone.
To give clarity of what is expected of our members, Swift has adopted the code of conduct defined by the Contributor Covenant. This document is used across many open source communities, and we think it articulates our values well. For more, see the Code of Conduct.
Getting Started
These instructions give the most direct path to a working Swift development environment. To build from source you will need about 2 GB of disk space for the source code and up to 70 GB of disk space for the build artifacts with full debugging. Depending on your machine, a clean build can take a few minutes to several hours. Naturally, incremental builds are much faster.
System Requirements
macOS, Ubuntu Linux LTS, and the latest Ubuntu Linux release are currently supported as host development operating systems.
Please make sure you use Python 2.x. Python 3.x is not supported currently.
macOS
To build for macOS, you need Xcode 11.2. The required version of Xcode changes frequently, and is often a beta release. Check this document or the host information on https://ci.swift.org for the current required version.
You will also need CMake and Ninja, which can be installed via a package manager:
brew install cmake ninja
sudo port install cmake ninja
Instructions for installing CMake and Ninja directly can be found below.
Linux
For Ubuntu, you'll need the following development dependencies:
sudo apt-get install git cmake ninja-build clang python uuid-dev libicu-dev icu-devtools libedit-dev libxml2-dev libsqlite3-dev swig libpython-dev libncurses5-dev pkg-config libcurl4-openssl-dev systemtap-sdt-dev tzdata rsync
Note: LLDB currently requires at least swig-1.3.40 but will successfully build
with version 2 shipped with Ubuntu.
Build instructions for Ubuntu 14.04 LTS can be found here.
Getting Sources for Swift and Related Projects
First create a directory for all of the Swift sources:
mkdir swift-source
cd swift-source
Note: This is important since update-checkout (see below) checks out repositories next to the Swift source directory. This means that if one clones Swift and has other unrelated repositories, update-checkout may not clone those repositories and will update them instead.
Via HTTPS For those checking out sources as read-only, HTTPS works best:
git clone https://github.com/apple/swift.git
./swift/utils/update-checkout --clone
Via SSH For those who plan on regularly making direct commits, cloning over SSH may provide a better experience (which requires uploading SSH keys to GitHub):
git clone git@github.com:apple/swift.git
./swift/utils/update-checkout --clone-with-ssh
Building Swift
The build-script is a high-level build automation script that supports basic
options such as building a Swift-compatible LLDB, building the Swift Package
Manager, building for various platforms, running tests after builds, and more.
There are two primary build systems to use: Xcode and Ninja. The Xcode build system allows you to work in Xcode, but Ninja is a bit faster and supports more environments.
First, make sure that you're in the swift directory:
cd swift
To build using Ninja, run:
utils/build-script --release-debuginfo
When developing Swift, it helps to build what you're working on in a debug configuration while building the rest of the project with optimizations. Below are some examples of using debug variants:
utils/build-script --release-debuginfo --debug-swift # Swift frontend built in debug
utils/build-script --release-debuginfo --debug-swift-stdlib # Standard library built in debug
utils/build-script --release-debuginfo --debug-swift --force-optimized-typechecker # Swift frontend sans type checker built in debug
Limiting the amount of debug code in the compiler has a very large impact on Swift compile times, and in turn the test execution time. If you want to build the entire project in debug, you can run:
utils/build-script --debug
For documentation of all available arguments, as well as additional usage information, see the inline help:
utils/build-script -h
Xcode
To build using Xcode, specify the --xcode argument on any of the above commands.
Xcode can be used to edit the Swift source code, but it is not currently
fully supported as a build environment for SDKs other than macOS. The generated
Xcode project does not integrate with the test runner, but the tests can be run
with the 'check-swift' target.
Build Products
All of the build products are placed in swift-source/build/${TOOL}-${MODE}/${PRODUCT}-${PLATFORM}/.
If macOS Swift with Ninja in DebugAssert mode was built, all of the products
would be in swift-source/build/Ninja-DebugAssert/swift-macosx-x86_64/. It
helps to save this directory as an environment variable for future use.
export SWIFT_BUILD_DIR="~/swift-source/build/Ninja-DebugAssert/swift-macosx-x86_64"
Ninja
Once the first build has completed, Ninja can perform fast incremental builds of various products. These incremental builds are a big timesaver when developing and debugging.
cd ${SWIFT_BUILD_DIR}
ninja swift
This will build the Swift compiler, but will not rebuild the standard library or
any other target. Building the swift-stdlib target as an additional layer of
testing from time to time is also a good idea. To build just the standard
library, run:
ninja swift-stdlib
It is always a good idea to do a full build after using update-checkout.
Using Xcode
To open the Swift project in Xcode, open ${SWIFT_BUILD_DIR}/Swift.xcodeproj.
It will auto-create a lot of schemes for all of the available targets. A
common debug flow would involve:
- Select the 'swift' scheme.
- Pull up the scheme editor (⌘⇧<).
- Select the 'Arguments' tab and click the '+'.
- Add the command line options.
- Close the scheme editor.
- Build and run.
Another option is to change the scheme to "Wait for executable to be launched", then run the build product in Terminal.
Swift Toolchains
Building
Swift toolchains are created using the script build-toolchain. This script is used by swift.org's CI to produce snapshots and can allow for one to locally reproduce such builds for development or distribution purposes. A typical invocation looks like the following:
$ ./swift/utils/build-toolchain $BUNDLE_PREFIX
where $BUNDLE_PREFIX is a string that will be prepended to the build
date to give the bundle identifier of the toolchain's Info.plist. For
instance, if $BUNDLE_PREFIX was com.example, the toolchain
produced will have the bundle identifier com.example.YYYYMMDD. It
will be created in the directory you run the script with a filename
of the form: swift-LOCAL-YYYY-MM-DD-a-osx.tar.gz.
Beyond building the toolchain, build-toolchain also supports the
following (non-exhaustive) set of useful options::
--dry-run: Perform a dry run build. This is off by default.--test: Test the toolchain after it has been compiled. This is off by default.--distcc: Use distcc to speed up the build by distributing the c++ part of the swift build. This is off by default.
More options may be added over time. Please pass --help to
build-toolchain to see the full set of options.
Installing into Xcode
On macOS if one wants to install such a toolchain into Xcode:
- Untar and copy the toolchain to one of
/Library/Developer/Toolchains/or~/Library/Developer/Toolchains/. E.x.:
$ sudo tar -xzf swift-LOCAL-YYYY-MM-DD-a-osx.tar.gz -C /
$ tar -xzf swift-LOCAL-YYYY-MM-DD-a-osx.tar.gz -C ~/
The script also generates an archive containing debug symbols which can be installed over the main archive allowing symbolication of any compiler crashes.
$ sudo tar -xzf swift-LOCAL-YYYY-MM-DD-a-osx-symbols.tar.gz -C /
$ tar -xzf swift-LOCAL-YYYY-MM-DD-a-osx-symbols.tar.gz -C ~/
- Specify the local toolchain for Xcode's use via
Xcode->Toolchains.
Build Failures
Make sure you are using the correct release of Xcode.
If you have changed Xcode versions but still encounter errors that appear to
be related to the Xcode version, try passing --clean to build-script.
When a new version of Xcode is released, you can update your build without
recompiling the entire project by passing the --reconfigure option.
Make sure all repositories are up to date with the update-checkout command
described above.
Testing Swift
See docs/Testing.md, in particular the section on lit.py.
Learning More
Be sure to look through the docs directory for more information about the compiler. In particular, the documents titled Debugging the Swift Compiler and Continuous Integration for Swift are very helpful to understand before submitting your first PR.
Building Documentation
To read the compiler documentation, start by installing the Sphinx documentation generator tool by running the command:
easy_install -U "Sphinx < 2.0"
Once complete, you can build the Swift documentation by changing directory into
docs and typing make. This
compiles the .rst files in the docs
directory into HTML in the docs/_build/html directory.
Many of the docs are out of date, but you can see some historical design
documents in the docs directory.
Another source of documentation is the standard library itself, located in
stdlib. Much of the language is actually implemented in the library
(including Int), and the standard library gives some examples of what can be
expressed today.
Build Dependencies
CMake
CMake is the core infrastructure used to configure builds of Swift and its companion projects; at least version 3.4.3 is required.
On macOS, you can download the CMake Binary Distribution,
bundled as an application, copy it to /Applications, and add the embedded
command line tools to your PATH:
export PATH=/Applications/CMake.app/Contents/bin:$PATH
On Linux, if you have not already installed Swift's development dependencies, you can download and install the CMake package separately using the following command:
sudo apt-get install cmake
Ninja
Ninja is the current recommended build system for building Swift and is the default configuration generated by CMake. Pre-built packages are available for macOS and Linux distributions. You can also clone Ninja next to the other projects and it will be bootstrapped automatically:
Via HTTPS
git clone https://github.com/ninja-build/ninja.git && cd ninja
git checkout release
cat README
Via SSH
git clone git@github.com:ninja-build/ninja.git && cd ninja
git checkout release
cat README