build-native

name	build-native
description	Build openmls native libraries for different platforms. Use when user asks about building, compiling, or creating native libraries for iOS, Android, macOS, Linux, or Windows.

Build Native Libraries

Help with building the openmls_frb native library for all supported platforms.

Golden Rule

ALWAYS use Makefile commands. Never call cargo/scripts directly.

# CORRECT
make build ARGS="--target aarch64-apple-darwin"

# WRONG - never do this
cd rust && cargo build --release

Quick Reference

Command	What it builds	Output
make build	Current host platform (release)	rust/target/release/
make build ARGS="--target <rust-target>"	Specific Rust target	rust/target/<target>/release/
make build-android	All Android ABIs via cargo-ndk	rust/target/<target>/release/
make build-android ARGS="--target arm64-v8a"	One Android ABI	rust/target/<target>/release/
make build-web	WASM via wasm-pack	rust/target/wasm32/

The library artifact is libopenmls_frb.{dylib,so} / openmls_frb.dll (web: openmls_frb.js + openmls_frb_bg.wasm).

There is no per-platform packaging step in this repo: consumers get precompiled binaries from the GitHub Release openmls_frb-<version> via hook/build.dart (see build-openmls.yml for the CI build matrix). To make a local build visible to the hook, create a .skip_openmls_hook marker (see the header of hook/build.dart).

Deployment Targets

Minimum OS versions are sourced from .copier-answers.yml and enforced with make check-targets. CI sets them via IPHONEOS_DEPLOYMENT_TARGET, MACOSX_DEPLOYMENT_TARGET and cargo-ndk --platform; make build-android reads the Android minSdk via scripts/get_android_min_sdk.dart.

Prerequisites

Platform	Requirements
All	Rust toolchain (rustup, cargo), FVM
macOS / iOS	Xcode Command Line Tools (iOS: full Xcode)
Android	Android NDK + cargo-ndk (make setup-android)
Web	wasm-pack (make setup-web)
Windows	Visual Studio with C++
Linux	gcc/g++, cross-compilation tools for arm64

Rust Targets

Platform	Rust Target
Linux x86_64	x86_64-unknown-linux-gnu
Linux arm64	aarch64-unknown-linux-gnu
macOS arm64	aarch64-apple-darwin
macOS x86_64	x86_64-apple-darwin
iOS device	aarch64-apple-ios
iOS simulator arm64	aarch64-apple-ios-sim
iOS simulator x86_64	x86_64-apple-ios
Android arm64	aarch64-linux-android
Android arm	armv7-linux-androideabi
Android x86_64	x86_64-linux-android
Windows	x86_64-pc-windows-msvc
Web	wasm32-unknown-unknown

Troubleshooting

"cargo not found"

# Install Rust toolchain
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

"NDK not found" (Android)

# Check current NDK
echo $ANDROID_NDK_HOME

# Common paths
export ANDROID_NDK_HOME=~/Android/Sdk/ndk/26.3.11579264
export ANDROID_NDK_HOME=~/Library/Android/sdk/ndk/26.3.11579264

Build fails on Windows

• Ensure you're in "Developer PowerShell for VS"
• Or run vcvars64.bat first
• CI workaround: Remove Git's link.exe from PATH (conflicts with MSVC)

Other Useful Commands

# Full setup (installs all dependencies)
make setup

# Regenerate FRB bindings after Rust API changes
make codegen

# Show current crate version
make version