Steps to build LDK java bindings

build-ldk-java-bindings.md

How-to build LDK java bindings

Build LDK C bindings

1. Clone rust-lightning git repo2.

2. Install clang-12 and set it as the default version

   linux Ubuntu install and set it as the default version

   macos

   brew install llvm
   

3. Install rust-src

   linux

   rustup component add rust-src --toolchain nightly-x86_64-unknown-linux-gnu
   

   macos

   rustup component add rust-src --toolchain nightly-x86_64-apple-darwin
   

4. Run script to build bindings

   ./genbindings.sh ../rust-lightning true  >& genbindings.out
   

5. Check genbindings.out for any warning or error messages

Build LDK java bindings

1. Install open JDK 11 and maven

sudo apt update
sudo apt install openjdk-11-jdk maven

2. Clone ldk-garbagecollected repo

git clone git@github.com:lightningdevkit/ldk-garbagecollected.git
cd ldk-garbagecollected

3. Run java tests

export LD_LIBRARY_PATH=.
mvn test

All good, test passes.

Build JNI lib

1. Set rust toolchain

rustup default 1.51.0

2. Clone Matt's rust-lightning repo

git clone https://git.bitcoin.ninja/rust-lightning
cd rust-lightning
git checkout 2021-03-java-bindings-base
cd ..

3. Clone ldk-c-bindings repo

git clone git@github.com:lightningdevkit/ldk-c-bindings.git
cd ldk-c-bindings

4. Install tools

rustup target add wasm32-wasi

# clang 10.0.1, gcc 9.3.0, g++ 9.3.0, valgrind 3.15.0
cargo install cbindgen g++ valgrind

5. Generate bindings

./genbindings.sh ../rust-lightning true

This is where I'm stuck.. with error:

+ clang++ -Wall -Wno-nullability-completeness -pthread -std=c++11 -flto -O2 demo.cpp target/release/libldk.a -ldl
/usr/bin/ld: error: LLVM gold plugin has failed to create LTO module: Invalid record
clang: error: linker command failed with exit code 1 (use -v to see invocation)