Getting Started with Swift on Windows

clang (cross-compiling)

1. Setup Visual Studio Environment Variables

Building for Windows requires that the Visual Studio environment variables are setup similar to the values on Windows. The following assumes that WINKIT_ROOT points to the path where the Windows 10 SDK is available and that VC_ROOT points to the path where the Visual Studio VC headers and libraries are available. Currently, the runtime has been tested to build against the Windows 10 SDK at revision 10.10.586.

export WINKIT_ROOT=".../Windows Kits/10"
export VC_ROOT=".../Microsoft Visual Studio 14.0/VC"
export INCLUDE='${VC_ROOT}/include;${WINKIT_ROOT}/Include/10.0.10586.0/ucrt;${WINKIT_ROOT}/Include/10.0.10586.0/um;${WINKIT_ROOT}/Include/10.0.10586.0/shared'
export LIB='${VC_ROOT}/lib;${WINKIT_ROOT}/Lib/10.0.10586.0/ucrt/x86;${WINKIT_ROOT}/Lib/10.0.10586.0/um/x86'

2. Setup visualc and ucrt modules

The visualc.modulemap located at swift/stdlib/public/Platform/visualc.modulemap needs to be copied into ${VC_ROOT}/include. The ucrt.modulemap located at swift/stdlib/public/Platform/ucrt.modulemap needs to be copied into ${WINKIT_ROOT}/Include/10.0.10586.0/ucrt.

3. Configure the runtime to be built with the just built clang

Ensure that we use the tools from the just built LLVM and clang tools to build the Windows SDK. You will need to pass a few extra options to cmake via the build-script invocation to achieve this. You will need to expand out the path where llvm-ar and llvm-ranlib are built. These are needed to correctly build the static libraries. Note that cross-compiling will require the use of lld. Ensure that lld-link.exe (lld-link) is available to clang via your path. Additionally, the ICU headers and libraries need to be provided for the build.

--extra-cmake-options=-DSWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER=FALSE,-DCMAKE_AR=<path to llvm-ar>,-DCMAKE_RANLIB=<path to llvm-ranlib>,-DSWIFT_SDKS=WINDOWS,-DSWIFT_WINDOWS_ICU_I18N_INCLUDE=<path to ICU i18n includes>,-DSWIFT_WINDOWS_ICU_UC_INCLUDE=<path to ICU UC includes>,-DSWIFT_WINDOWS_ICU_I18N_LIB=<path to ICU i18n lib>,-DSWIFT_WINDOWS_ICU_UC_LIB=<path to ICU UC lib>

MSVC

  • Windows doesn‘t currently have a build script. You’ll need to run commands manually to build Swift on Windows.
  • Release/RelWithDebInfo modes have not been tested and may not be supported.
  • Windows support for Swift is very much a work in progress and may not work on your system.
  • Using the latest Visual Studio version is recommended. Swift may fail to build with older C++ compilers.

1. Install dependencies

  • Make sure to add Python, CMake and Ninja to your Path environment variable
  1. Latest version (2.7.12 tested) of Python 2
  2. Latest version (3.7.0-rc3 tested) of CMake
  3. Latest version (1.7.1 tested) of Ninja
  4. Latest version (2015 Update 3 tested) of Visual Studio
  • Make sure to include Programming Languages|Visual C++ and Windows and Web Development|Universal Windows App Development|Windows SDK in your installation.
  • Windows SDK 10.0.10240 was tested. Some later versions (e.g. 10.0.14393) are known not to work, as they are not supported by compiler-rt.

2. Clone the repositories

  1. Create a folder to contain all the Swift repositories
  2. apple/swift-cmark into a folder named cmark
  3. apple/swift-clang into a folder named clang
  4. apple/swift-llvm into a folder named llvm
  5. apple/swift into a folder named swift
  • Currently, other repositories in the Swift project have not been tested and may not be supported.

3. Build ICU

  1. Download and extract the ICU source code to a folder named icu in the same directory as the other Swift project repositories.
  2. Open src/win32/allinone.sln in Visual Studio.
  3. Make sure to select the correct architecture from the drop-down in Visual Studio.
  4. Right click on the solution in the Solution Explorer window and select Build Solution.
  5. When this is done, add the <icu-source>/bin folder to your Path environment variable.

4. Get ready

  • From within a developer command prompt, execute the following command if you have an x64 PC.
VsDevCmd -arch=amd64
  • Then adapt the following command and run it.
set swift_source_dir=path-to-directory-containing-all-cloned-repositories

5. Build CMark

  • This must be done from within a developer command prompt. CMark is a fairly small project and should only take a few minutes to build.
mkdir "%swift_source_dir%/build/Ninja-DebugAssert/cmark-windows-amd64"
pushd "%swift_source_dir%/build/Ninja-DebugAssert/cmark-windows-amd64"
cmake -G "Ninja" "%swift_source_dir%/cmark"
popd
cmake --build "%swift_source_dir%/build/Ninja-DebugAssert/cmark-windows-amd64/"

6. Build LLVM/Clang/Compiler-RT

  • This must be done from within a developer command prompt. LLVM and Clang are large projects so building might take a few hours. Make sure that the build type (e.g. Debug/Release) for LLVM/Clang matches the build type for Swift.
  • Optionally, you can omit building compiler-rt by removing all lines referring to compiler-rt below, which should give faster build times.
mklink /J "%swift_source_dir%/llvm/tools/clang" "%swift_source_dir%/clang"
mklink /J "%swift_source_dir%/llvm/tools/compiler-rt" "%swift_source_dir%/compiler-rt"
mkdir "%swift_source_dir%/build/Ninja-DebugAssert/llvm-windows-amd64"
pushd "%swift_source_dir%/build/Ninja-DebugAssert/llvm-windows-amd64"
cmake -G "Ninja"^
 -DLLVM_ENABLE_ASSERTIONS=TRUE^
 -DCMAKE_BUILD_TYPE=Debug^
 -DLLVM_TOOL_SWIFT_BUILD=NO^
 -DLLVM_INCLUDE_DOCS=TRUE^
 -DLLVM_TOOL_COMPILER_RT_BUILD=TRUE^
 -DLLVM_BUILD_EXTERNAL_COMPILER_RT=TRUE^
 -DLLVM_LIT_ARGS=-sv^
 "%swift_source_dir%/llvm"
popd
cmake --build "%swift_source_dir%/build/Ninja-DebugAssert/llvm-windows-amd64"

7. Build Swift

  • This must be done from within a developer command prompt and could take up to two hours depending on your system.
  • You may need to adjust the SWIFT_WINDOWS_LIB_DIRECTORY parameter depending on your target platform or Windows SDK version.
  • While the commands here use MSVC to build, using clang-cl is recommended (see the Clang-cl section below).
mkdir "%swift_source_dir%/build/Ninja-DebugAssert/swift-windows-amd64/ninja"
pushd "%swift_source_dir%/build/Ninja-DebugAssert/swift-windows-amd64/ninja"
cmake -G "Ninja" "%swift_source_dir%/swift"^
 -DCMAKE_BUILD_TYPE=Debug^
 -DSWIFT_PATH_TO_CMARK_SOURCE="%swift_source_dir%/cmark"^
 -DSWIFT_PATH_TO_CMARK_BUILD="%swift_source_dir%/build/Ninja-DebugAssert/cmark-windows-amd64"^
 -DSWIFT_CMARK_LIBRARY_DIR="%swift_source_dir%/build/Ninja-DebugAssert/cmark-windows-amd64/src"^
 -DSWIFT_PATH_TO_LLVM_SOURCE="%swift_source_dir%/llvm"^
 -DSWIFT_PATH_TO_LLVM_BUILD="%swift_source_dir%/build/Ninja-DebugAssert/llvm-windows-amd64"^
 -DSWIFT_PATH_TO_CLANG_SOURCE="%swift_source_dir%/llvm/tools/clang"^
 -DSWIFT_PATH_TO_CLANG_BUILD="%swift_source_dir%/build/Ninja-DebugAssert/llvm-windows-amd64"^
 -DICU_UC_INCLUDE_DIRS="%swift_source_dir%/icu/include"^
 -DICU_UC_LIBRARY_DIRS="%swift_source_dir%/icu/lib64"^
 -DICU_I18N_INCLUDE_DIRS="%swift_source_dir%/icu/include"^
 -DICU_I18N_LIBRARY_DIRS="%swift_source_dir%/icu/lib64"^
 -DICU_UC_LIB_NAME="icuuc"^
 -DICU_I18N_LIB_NAME="icuin"^
 -DSWIFT_INCLUDE_DOCS=FALSE^
 -DSWIFT_INCLUDE_TESTS=FALSE^
 -DSWIFT_BUILD_DYNAMIC_SDK_OVERLAY=FALSE^
 -DSWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER=FALSE
popd
cmake --build "%swift_source_dir%/build/Ninja-DebugAssert/swift-windows-amd64/ninja"
  • To create a VisualStudio project, you'll need to change the generator and, if you have a 64 bit processor, specify the generator platform. Note that you may get multiple build errors compiling the swift project due to an MSBuild limitation that file paths cannot exceed 260 characters. These can be ignored, as they occur after the build when writing the last build status to a file.
cmake -G "Visual Studio 15" "%swift_source_dir%/swift"^
 -DCMAKE_GENERATOR_PLATFORM="x64"^
 ...

Clang-cl

Follow the instructions for MSVC, but add the following lines to each CMake configuration command. Clang-cl 4.0.1 has been tested. You can remove the SWIFT_BUILD_DYNAMIC_SDK_OVERLAY=FALSE definition, as overlays are supported with clang-cl, as it supports modules. The Z7 flag is required to produce PDB files that MSVC's link.exe can read, and also enables proper stack traces.

 -DCMAKE_C_COMPILER="<path-to-llvm-bin>/clang-cl.exe"^
 -DCMAKE_CXX_COMPILER="<path-to-llvm-bin>/bin/clang-cl.exe"^
 -DCMAKE_C_FLAGS="-fms-compatibility-version=19.00 /Z7"^
 -DCMAKE_CXX_FLAGS="-fms-compatibility-version=19.00 -Z7" ^

Windows Subsystem for Linux (WSL)

  • Note that all compiled Swift binaries are only executable within Bash on Windows and are Ubuntu, not Windows, executables.
  • Make sure to run all commands from Bash, or the project won't compile.

1. Install WSL

Install and run the latest version of Bash on Ubuntu on Windows installed on your PC.

bash

2. Install dependencies

Install the developer dependencies needed to compile the Swift project. These are identical to the Ubuntu dependencies, with the addition of make.

sudo apt-get install git make cmake ninja-build clang python uuid-dev libicu-dev icu-devtools libbsd-dev libedit-dev libxml2-dev libsqlite3-dev swig libpython-dev libncurses5-dev pkg-config libblocksruntime-dev libcurl4-openssl-dev

3. Upgrade clang

Install a version of clang with C++ 14 support - the default version of clang on WSL results in linker errors during compilation.

sudo apt-get install clang-3.6
sudo update-alternatives --install /usr/bin/clang clang /usr/bin/clang-3.6 100
sudo update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-3.6 100

4. Upgrade CMake

Install the latest version of CMake - Swift uses new CMake features such as IN_LIST and won't build without these features.

wget http://www.cmake.org/files/v3.6/cmake-3.6.2.tar.gz
tar xf cmake-3.6.2.tar.gz
cd cmake-3.6.2
./configure
make
sudo make install
sudo update-alternatives --install /usr/bin/cmake cmake /usr/local/bin/cmake 1 --force
cmake --version # This should print 3.6.2

6. Clone and build the Swift project

mkdir swift-source
cd swift-source
git clone https://github.com/apple/swift.git
./swift/utils/update-checkout --clone
./swift/utils/build-script -r

7. Hello, Windows (Subsystem for Linux)

cd ./build/Ninja-RelWithDebInfoAssert/swift-linux-x86_64/bin # This path may depend on your build configuration
echo 'print("Hello, Windows")' >> test.swift
swiftc test.swift
./test # Hello, Windows