mirror of
https://github.com/oven-sh/bun
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## 🐛 Problem Fixes #21907 - CSS parser was crashing with "integer part of floating point value out of bounds" when processing extremely large floating-point values like `3.40282e38px` (commonly generated by TailwindCSS `.rounded-full` class). ### Root Cause Analysis **This revealed a broader systemic issue**: The CSS parser was ported from Rust, which has different float→integer conversion semantics than Zig's `@intFromFloat`. **Zig behavior**: `@intFromFloat` panics on out-of-range values **Rust behavior**: `as` operator follows safe conversion rules: - Finite values within range: truncate toward zero - NaN: becomes 0 - Positive infinity: becomes target max value - Negative infinity: becomes target min value - Out-of-range finite values: clamp to target range The crash occurred throughout the CSS codebase wherever `@intFromFloat` was used, not just in the original failing location. ## 🔧 Comprehensive Solution ### 1. New Generic `bun.intFromFloat` Function Created a reusable function in `src/bun.zig` that implements Rust-compatible conversion semantics: ```zig pub fn intFromFloat(comptime Int: type, value: anytype) Int { // Handle NaN -> 0 if (std.math.isNan(value)) return 0; // Handle infinities -> min/max bounds if (std.math.isPositiveInf(value)) return std.math.maxInt(Int); if (std.math.isNegativeInf(value)) return std.math.minInt(Int); // Handle out-of-range values -> clamp to bounds const min_float = @as(Float, @floatFromInt(std.math.minInt(Int))); const max_float = @as(Float, @floatFromInt(std.math.maxInt(Int))); if (value > max_float) return std.math.maxInt(Int); if (value < min_float) return std.math.minInt(Int); // Safe conversion for in-range values return @as(Int, @intFromFloat(value)); } ``` ### 2. Systematic Replacement Across CSS Codebase Replaced **all 18 instances** of `@intFromFloat` in `src/css/` with `bun.intFromFloat`: | File | Conversions | Purpose | |------|-------------|---------| | `css_parser.zig` | 2 × `i32` | CSS dimension serialization | | `css_internals.zig` | 9 × `u32` | Browser target version parsing | | `values/color.zig` | 4 × `u8` | Color component conversion | | `values/color_js.zig` | 1 × `i64→u8` | Alpha channel processing | | `values/percentage.zig` | 1 × `i32` | Percentage value handling | | `properties/custom.zig` | 1 × `i32` | Color helper function | ### 3. Comprehensive Test Coverage - **New test suite**: `test/internal/int_from_float.test.ts` with inline snapshots - **Enhanced regression test**: `test/regression/issue/21907.test.ts` covering all conversion types - **Real-world testing**: Validates actual CSS processing with edge cases ## 📊 esbuild Compatibility Analysis Compared output with esbuild to ensure compatibility: **Test CSS:** ```css .test { border-radius: 3.40282e38px; } .colors { color: rgb(300, -50, 1000); } .boundaries { width: 2147483648px; } ``` **Key Differences:** 1. **Scientific notation format:** - esbuild: `3.40282e38` (no explicit + sign) - Bun: `3.40282e+38` (explicit + sign) - ✅ Both are mathematically equivalent and valid CSS 2. **Optimization strategy:** - esbuild: Preserves original literal values - Bun: Normalizes extremely large values + consolidates selectors - ✅ Bun's more aggressive optimization results in smaller output ### ❓ Question for Review **@zackradisic** - Is it acceptable for Bun to diverge from esbuild in this optimization behavior? - **Pro**: More aggressive optimization (smaller output, consistent formatting) - **Con**: Different output format than esbuild - **Impact**: Both outputs are functionally identical in browsers Should we: 1. ✅ Keep current behavior (more aggressive optimization) 2. 🔄 Match esbuild exactly (preserve literal notation) 3. 🎛️ Add flag to control this behavior ## ✅ Testing & Validation - [x] **Original crash case**: Fixed - no more panics with large floating-point values - [x] **All conversion types**: Tested i32, u32, u8, i64 conversions with edge cases - [x] **Browser compatibility**: Verified targets parsing works with extreme values - [x] **Color processing**: Confirmed RGB/RGBA values properly clamped to 0-255 range - [x] **Performance**: No regression - conversions are equally fast - [x] **Real-world**: TailwindCSS projects with `.rounded-full` work without crashes - [x] **Inline snapshots**: Capture exact expected output for future regression detection ## 🎯 Impact ### Before (Broken) ```bash $ bun build styles.css ============================================================ panic: integer part of floating point value out of bounds ``` ### After (Working) ```bash $ bun build styles.css Bundled 1 module in 93ms styles.css 121 bytes (asset) ``` - ✅ **Fixes crashes** when using TailwindCSS `.rounded-full` class on Windows - ✅ **Maintains backward compatibility** for existing projects - ✅ **Improves robustness** across all CSS float→int conversions - ✅ **Better optimization** with consistent value normalization 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com> --------- Co-authored-by: Claude Bot <claude-bot@bun.sh> Co-authored-by: Claude <noreply@anthropic.com> Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Bun
Read the docs →
What is Bun?
Bun is an all-in-one toolkit for JavaScript and TypeScript apps. It ships as a single executable called bun.
At its core is the Bun runtime, a fast JavaScript runtime designed as a drop-in replacement for Node.js. It's written in Zig and powered by JavaScriptCore under the hood, dramatically reducing startup times and memory usage.
bun run index.tsx # TS and JSX supported out-of-the-box
The bun command-line tool also implements a test runner, script runner, and Node.js-compatible package manager. Instead of 1,000 node_modules for development, you only need bun. Bun's built-in tools are significantly faster than existing options and usable in existing Node.js projects with little to no changes.
bun test # run tests
bun run start # run the `start` script in `package.json`
bun install <pkg> # install a package
bunx cowsay 'Hello, world!' # execute a package
Install
Bun supports Linux (x64 & arm64), macOS (x64 & Apple Silicon) and Windows (x64).
Linux users — Kernel version 5.6 or higher is strongly recommended, but the minimum is 5.1.
x64 users — if you see "illegal instruction" or similar errors, check our CPU requirements
# with install script (recommended)
curl -fsSL https://bun.com/install | bash
# on windows
powershell -c "irm bun.com/install.ps1 | iex"
# with npm
npm install -g bun
# with Homebrew
brew tap oven-sh/bun
brew install bun
# with Docker
docker pull oven/bun
docker run --rm --init --ulimit memlock=-1:-1 oven/bun
Upgrade
To upgrade to the latest version of Bun, run:
bun upgrade
Bun automatically releases a canary build on every commit to main. To upgrade to the latest canary build, run:
bun upgrade --canary
Quick links
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Intro
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Templating
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CLI
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Runtime
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Package manager
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Bundler
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Test runner
-
Package runner
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API
- HTTP server (
Bun.serve) - WebSockets
- Workers
- Binary data
- Streams
- File I/O (
Bun.file) - import.meta
- SQLite (
bun:sqlite) - PostgreSQL (
Bun.sql) - Redis (
Bun.redis) - S3 Client (
Bun.s3) - FileSystemRouter
- TCP sockets
- UDP sockets
- Globals
- $ Shell
- Child processes (spawn)
- Transpiler (
Bun.Transpiler) - Hashing
- Colors (
Bun.color) - Console
- FFI (
bun:ffi) - C Compiler (
bun:fficc) - HTMLRewriter
- Testing (
bun:test) - Cookies (
Bun.Cookie) - Utils
- Node-API
- Glob (
Bun.Glob) - Semver (
Bun.semver) - DNS
- fetch API extensions
- HTTP server (
Guides
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Binary
- Convert a Blob to a string
- Convert a Buffer to a blob
- Convert a Blob to a DataView
- Convert a Buffer to a string
- Convert a Blob to a ReadableStream
- Convert a Blob to a Uint8Array
- Convert a DataView to a string
- Convert a Uint8Array to a Blob
- Convert a Blob to an ArrayBuffer
- Convert an ArrayBuffer to a Blob
- Convert a Buffer to a Uint8Array
- Convert a Uint8Array to a Buffer
- Convert a Uint8Array to a string
- Convert a Buffer to an ArrayBuffer
- Convert an ArrayBuffer to a Buffer
- Convert an ArrayBuffer to a string
- Convert a Uint8Array to a DataView
- Convert a Buffer to a ReadableStream
- Convert a Uint8Array to an ArrayBuffer
- Convert an ArrayBuffer to a Uint8Array
- Convert an ArrayBuffer to an array of numbers
- Convert a Uint8Array to a ReadableStream
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Ecosystem
- Use React and JSX
- Use EdgeDB with Bun
- Use Prisma with Bun
- Add Sentry to a Bun app
- Create a Discord bot
- Run Bun as a daemon with PM2
- Use Drizzle ORM with Bun
- Build an app with Nuxt and Bun
- Build an app with Qwik and Bun
- Build an app with Astro and Bun
- Build an app with Remix and Bun
- Build a frontend using Vite and Bun
- Build an app with Next.js and Bun
- Run Bun as a daemon with systemd
- Deploy a Bun application on Render
- Build an HTTP server using Hono and Bun
- Build an app with SvelteKit and Bun
- Build an app with SolidStart and Bun
- Build an HTTP server using Elysia and Bun
- Build an HTTP server using StricJS and Bun
- Containerize a Bun application with Docker
- Build an HTTP server using Express and Bun
- Use Neon Postgres through Drizzle ORM
- Server-side render (SSR) a React component
- Read and write data to MongoDB using Mongoose and Bun
- Use Neon's Serverless Postgres with Bun
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HTMLRewriter
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HTTP
- Hot reload an HTTP server
- Common HTTP server usage
- Write a simple HTTP server
- Configure TLS on an HTTP server
- Send an HTTP request using fetch
- Proxy HTTP requests using fetch()
- Start a cluster of HTTP servers
- Stream a file as an HTTP Response
- fetch with unix domain sockets in Bun
- Upload files via HTTP using FormData
- Streaming HTTP Server with Async Iterators
- Streaming HTTP Server with Node.js Streams
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Install
- Add a dependency
- Add a Git dependency
- Add a peer dependency
- Add a trusted dependency
- Add a development dependency
- Add a tarball dependency
- Add an optional dependency
- Generate a yarn-compatible lockfile
- Configuring a monorepo using workspaces
- Install a package under a different name
- Install dependencies with Bun in GitHub Actions
- Using bun install with Artifactory
- Configure git to diff Bun's lockb lockfile
- Override the default npm registry for bun install
- Using bun install with an Azure Artifacts npm registry
- Migrate from npm install to bun install
- Configure a private registry for an organization scope with bun install
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Process
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Read file
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Runtime
- Delete files
- Run a Shell Command
- Import a JSON file
- Import a TOML file
- Set a time zone in Bun
- Set environment variables
- Re-map import paths
- Delete directories
- Read environment variables
- Import a HTML file as text
- Install and run Bun in GitHub Actions
- Debugging Bun with the web debugger
- Install TypeScript declarations for Bun
- Debugging Bun with the VS Code extension
- Inspect memory usage using V8 heap snapshots
- Define and replace static globals & constants
- Codesign a single-file JavaScript executable on macOS
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Streams
- Convert a ReadableStream to JSON
- Convert a ReadableStream to a Blob
- Convert a ReadableStream to a Buffer
- Convert a ReadableStream to a string
- Convert a ReadableStream to a Uint8Array
- Convert a ReadableStream to an array of chunks
- Convert a Node.js Readable to JSON
- Convert a ReadableStream to an ArrayBuffer
- Convert a Node.js Readable to a Blob
- Convert a Node.js Readable to a string
- Convert a Node.js Readable to an Uint8Array
- Convert a Node.js Readable to an ArrayBuffer
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Test
- Spy on methods in
bun test - Bail early with the Bun test runner
- Mock functions in
bun test - Run tests in watch mode with Bun
- Use snapshot testing in
bun test - Skip tests with the Bun test runner
- Using Testing Library with Bun
- Update snapshots in
bun test - Run your tests with the Bun test runner
- Set the system time in Bun's test runner
- Set a per-test timeout with the Bun test runner
- Migrate from Jest to Bun's test runner
- Write browser DOM tests with Bun and happy-dom
- Mark a test as a "todo" with the Bun test runner
- Re-run tests multiple times with the Bun test runner
- Generate code coverage reports with the Bun test runner
- import, require, and test Svelte components with bun test
- Set a code coverage threshold with the Bun test runner
- Spy on methods in
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Util
- Generate a UUID
- Hash a password
- Escape an HTML string
- Get the current Bun version
- Encode and decode base64 strings
- Compress and decompress data with gzip
- Sleep for a fixed number of milliseconds
- Detect when code is executed with Bun
- Check if two objects are deeply equal
- Compress and decompress data with DEFLATE
- Get the absolute path to the current entrypoint
- Get the directory of the current file
- Check if the current file is the entrypoint
- Get the file name of the current file
- Convert a file URL to an absolute path
- Convert an absolute path to a file URL
- Get the absolute path of the current file
- Get the path to an executable bin file
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WebSocket
-
Write file
Contributing
Refer to the Project > Contributing guide to start contributing to Bun.
License
Refer to the Project > License page for information about Bun's licensing.