{ rustPlatform, rust-riscv32i-crates, binutils-riscv32, rustc, cargo }:

rustPlatform.buildRustPackage rec {
  name = "helloworld";
  version = "0.0.0";

  src = ./.;
  cargoSha256 = "0kf2pnfylfmzm0qvi4jfci43qvrnj1v5f037sb9zpvfqyddhdffl";

  # HACK - rustc overlay does not update rustPlatform. Find out why.
  configurePhase = ''echo XXX ${rustPlatform.rust.rustc} ${rustPlatform.rust.cargo}'';

  buildPhase = ''
    export CARGO_HOME=$(mktemp -d cargo-home.XXX)
    export RUSTFLAGS="-L ${rust-riscv32i-crates}/lib/rustlib/riscv32i-unknown-none-elf/lib -C linker=${binutils-riscv32}/bin/riscv32-unknown-elf-ld -C link-arg=-Tlink.x"
    export RUSTC=${rustc}/bin/rustc
    ${cargo}/bin/cargo build --release --target riscv32i-unknown-none-elf
  '';

  doCheck = false;
  installPhase = ''
    mkdir -p $out
    cp target/riscv32i-unknown-none-elf/release/helloworld $out
    ${binutils-riscv32}/bin/riscv32-unknown-elf-objcopy -O binary target/riscv32i-unknown-none-elf/release/helloworld $out/helloworld.bin
  '';
}