build-dart-sdk

name	build-dart-sdk
description	Build the Dart SDK compilers and VM runtime. Use when you need to compile the SDK, build specific targets (runtime, most, create_sdk, dart2js, analysis_server), or troubleshoot build issues.
disable-model-invocation	true
allowed-tools	Bash

Build the Dart SDK

Official docs: docs/Building.md

Prerequisites

• depot_tools in PATH (see setup-dart-sdk-dev skill)
• gclient workspace synced (see below)
• macOS: Xcode installed (not just command-line tools)

Quick build

bash .claude/skills/build-dart-sdk/scripts/build.sh

This builds the most target in release mode (analysis_server, dart2js, DDC, runtime, create_sdk).

Build specific targets

# Just the VM runtime (fastest build)
bash .claude/skills/build-dart-sdk/scripts/build.sh runtime

# Full SDK distribution
bash .claude/skills/build-dart-sdk/scripts/build.sh create_sdk

# Specific compiler
bash .claude/skills/build-dart-sdk/scripts/build.sh dart2js
bash .claude/skills/build-dart-sdk/scripts/build.sh analysis_server

# Multiple targets
bash .claude/skills/build-dart-sdk/scripts/build.sh most run_ffi_unit_tests

Build modes

# Debug mode (default for development)
bash .claude/skills/build-dart-sdk/scripts/build.sh --mode debug runtime

# Release mode (default for this script)
bash .claude/skills/build-dart-sdk/scripts/build.sh --mode release most

Gclient sync (required before first build)

bash .claude/skills/build-dart-sdk/scripts/build.sh sync

This sets up the gclient workspace and downloads all native dependencies. Required once, then again after pulling new changes that modify DEPS.

Output directories

Platform	Debug	Release
macOS arm64	xcodebuild/DebugARM64/	xcodebuild/ReleaseARM64/
macOS x64	xcodebuild/DebugX64/	xcodebuild/ReleaseX64/
Linux/Windows	out/DebugX64/	out/ReleaseX64/

Common build targets

Target	What it builds	Time
runtime	VM only	Fast
most	analysis_server, dart2js, DDC, runtime, create_sdk	Medium
create_sdk	Full SDK distribution	Medium
dart2js	dart2js compiler only	Medium
analysis_server	Analysis server only	Medium
run_ffi_unit_tests	FFI unit tests (needed before running tests)	Fast

Troubleshooting

• No gclient workspace: Run bash .claude/skills/build-dart-sdk/scripts/build.sh sync first
• Stale deps after branch switch: Run gclient sync -D from the workspace root
• Xcode errors on macOS: Ensure full Xcode is installed, not just command-line tools
• Python errors: Ensure Python 3 is available as python3