Build Windows EXEs from macOS

(also check out the Windows Platform page for info about developing for Windows generally)

Rust offers two different toolchains for building for Windows:

• MSVC: the default when working in Windows, requires downloading Microsoft SDKs
• GNU: alternative MINGW-based build

On macOS, the GNU software is not readily-available. I don't know how it could be installed. Even if possible, it might be difficult to set up.

This page will teach you how to setup a MSVC-based toolchain, which works on macOS and can be set up similarly to how it can be done on Linux.. You will need to accept Microsoft licenses.

The instructions on this page use the x86_64 architecture, but you could also set up a toolchain to target i686 (32-bit) or aarch64 (Windows-on-Arm) the same way.

First-Time Setup

Rust Toolchain

Add the target to your Rust installation (assuming you use rustup):

rustup target add x86_64-pc-windows-msvc

This installs the files Rust needs to compile for Windows, including the Rust standard library.

Microsoft Windows SDKs

You need to install the Microsoft Windows SDKs, just like when working on Windows. This can be done with an easy script called xwin. You need to accept Microsoft's proprietary license.

Install xwin:

cargo install xwin

Now, use xwin to accept the Microsoft license, download all the files from Microsoft servers, and install them to a directory of your choosing.

(The --accept-license option is to not prompt you, assuming you have already seen the license. To read the license and be prompted to accept it, omit that option.)

To install to .xwin/ in your home folder:

xwin --accept-license splat --disable-symlinks --output /Users/me/.xwin

On Windows and macOS, the filesystem is case-insensitive. On Linux and BSD, the filesystem is case-sensitive. xwin was made for Linux, so it tries to work around this by default, by creating symlinks. On macOS, we need to tell xwin not to do this, using the --disable-symlinks option.

Linking

Rust needs to know how to link the final EXE file.

The default Microsoft linker (link.exe) is only available on Windows. Instead, we need to use the LLD linker (this is also recommended when working on Windows anyway).

Installing LLD

Unfortunately, last I checked, neither brew nor macports offer packages (LLD is not commonly used when developing for macOS).

We can, however, build it ourselves from source. You need a C++ compiler and CMake. You probably already have the C++ toolchain installed, if you have installed Apple XCode development tools.

CMake can be installed from brew (Homebrew):

brew install cmake

Now, we are ready to compile LLD from the LLVM project:

Note: the --depth=1 option to git clone allows us to save a lot of disk space and download bandwidth, because the LLVM respository is huge.

git clone --depth=1 https://github.com/llvm/llvm-project
cd llvm-project
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS=lld -DCMAKE_INSTALL_PREFIX=/usr/local ../llvm
sudo make -j10 install # adjust `-j10` based on your number of CPU cores
cd ../../; rm -rf llvm-project # delete the git repo and build files to free disk space

This will install it to /usr/local. Change the path above if you would rather have it somewhere else, to not pollute your macOS or need sudo / root privileges.

Using LLD

We also need to tell Rust to use our linker, and the location of the Microsoft Windows SDK libraries (that were installed with xwin in the previous step).

Add this to .cargo/config.toml (in your home folder or in your bevy project):

[target.x86_64-pc-windows-msvc]
linker = "/usr/local/bin/lld"
rustflags = [
  "-Lnative=/Users/me/.xwin/crt/lib/x86_64",
  "-Lnative=/Users/me/.xwin/sdk/lib/um/x86_64",
  "-Lnative=/Users/me/.xwin/sdk/lib/ucrt/x86_64"
]

Note: you need to specify the correct full absolute paths to the SDK files, wherever you installed them.

Building Your Project

Finally, with all the setup done, you can just build your Rust/Bevy projects for Windows:

cargo build --target=x86_64-pc-windows-msvc --release