{ stdenv, rustc, fetchFromGitHub }:
let
  compiler-builtins-src = fetchFromGitHub {
    owner = "rust-lang-nursery";
    repo = "compiler-builtins";
    rev = "0.1.12";
    sha256 = "0hkssvrh952kcz7w7aws3pqr05barg3qppqpji641b35xpbg9gyg";
  };
in
  stdenv.mkDerivation {
    name = "rust-riscv32i-crates";
    src = rustc.src;
    phases = [ "unpackPhase" "buildPhase" ];
    buildPhase = ''
      destdir=$out/lib/rustlib/riscv32i-unknown-none-elf/lib/
      rustc="${rustc}/bin/rustc --out-dir ''${destdir} -L ''${destdir} --target riscv32i-unknown-none-elf -g -C opt-level=s --crate-type rlib"

      mkdir -p ''${destdir}
      export RUSTC_BOOTSTRAP=1
      ''${rustc} --crate-name core src/libcore/lib.rs
      ''${rustc} --crate-name compiler_builtins ${compiler-builtins-src}/src/lib.rs --cfg 'feature="compiler-builtins"' --cfg 'feature="mem"'
    '';
    #  ''${rustc} --crate-name alloc src/liballoc/lib.rs
    #  ''${rustc} --crate-name libc ${./libc_mini.rs}
    #  ''${rustc} --crate-name unwind src/libunwind/lib.rs
    #  ''${rustc} --crate-name std src/libstd/lib.rs
    #  ''${rustc} -Cpanic=abort --crate-name panic_abort src/libpanic_abort/lib.rs
    #  ''${rustc} -Cpanic=unwind --crate-name panic_unwind src/libpanic_unwind/lib.rs --cfg llvm_libunwind
  }