This document describes the build process for Windows. If you run into problems, please join the #contributing channel on our Discord for help.
It is strongly recommended to use PowerShell 7 (pwsh.exe) instead of the default powershell.exe.
Prerequisites
Enable Scripts
By default, running unverified scripts are blocked.
Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy UnrestrictedSystem Dependencies
Bun v1.1 or later. We use Bun to run it's own code generators.
irm bun.sh/install.ps1 | iexVisual Studio with the "Desktop Development with C++" workload. While installing, make sure to install Git as well, if Git for Windows is not already installed.
Visual Studio can be installed graphically using the wizard or through WinGet:
winget install "Visual Studio Community 2022" --override "--add Microsoft.VisualStudio.Workload.NativeDesktop Microsoft.VisualStudio.Component.Git " -s msstoreAfter Visual Studio, you need the following:
- LLVM 18.1.8
- Go
- Rust
- NASM
- Perl
- Ruby
- Node.js
- Ccache
Note – The Zig compiler is automatically downloaded, installed, and updated by the building process.
Scoop can be used to install these remaining tools easily.
irm https://get.scoop.sh | iexscoop install nodejs-lts go rust nasm ruby perl ccache# scoop seems to be buggy if you install llvm and the rest at the same timescoop install llvm@18.1.8Please do not use WinGet/other package manager for these, as you will likely install Strawberry Perl instead of a more minimal installation of Perl. Strawberry Perl includes many other utilities that get installed into $Env:PATH that will conflict with MSVC and break the build.
If you intend on building WebKit locally (optional), you should install these packages:
scoop install make cygwin pythonFrom here on out, it is expected you use a PowerShell Terminal with .\scripts\vs-shell.ps1 sourced. This script is available in the Bun repository and can be loaded by executing it:
.\scripts\vs-shell.ps1To verify, you can check for an MSVC-only command line such as mt.exe
Get-Command mtIt is not recommended to install ninja / cmake into your global path, because you may run into a situation where you try to build bun without .\scripts\vs-shell.ps1 sourced.
Building
bun run build
# after the initial `bun run build` you can use the following to buildninja -Cbuild/debugIf this was successful, you should have a bun-debug.exe in the build/debug folder.
.\build\debug\bun-debug.exe --revisionYou should add this to $Env:PATH. The simplest way to do so is to open the start menu, type "Path", and then navigate the environment variables menu to add C:\.....\bun\build\debug to the user environment variable PATH. You should then restart your editor (if it does not update still, log out and log back in).
Extra paths
- WebKit is extracted to
build/debug/cache/webkit/ - Zig is extracted to
build/debug/cache/zig/bin/zig.exe
Tests
You can run the test suite either using bun test <path>, or by using the wrapper script packages\bun-internal-test. The internal test package is a wrapper cli to run every test file in a separate instance of bun.exe, to prevent a crash in the test runner from stopping the entire suite.
# Setupbun i --cwd packages\bun-internal-test
# Run the entire test suite with reporter
# the package.json script "test" uses "build/debug/bun-debug.exe" by defaultbun run test
# Run an individual test file:bun-debug test node\fsbun-debug test "C:\bun\test\js\bun\resolve\import-meta.test.js"Troubleshooting
.rc file fails to build
llvm-rc.exe is odd. don't use it. use rc.exe, to do this make sure you are in a visual studio dev terminal, check rc /? to ensure it is Microsoft Resource Compiler
failed to write output 'bun-debug.exe': permission denied
you cannot overwrite bun-debug.exe if it is already open. you likely have a running instance, maybe in the vscode debugger?