self: super:
rec {
  yosys = super.yosys.overrideAttrs(oa: rec {
    name = "yosys-${version}";
    version = "0.9";
    srcs = [
      (super.fetchFromGitHub {
        owner  = "yosyshq";
        repo   = "yosys";
        rev    = "yosys-${version}";
        sha256 = "0lb9r055h8y1vj2z8gm4ip0v06j5mk7f9zx9gi67kkqb7g4rhjli";
        name   = "yosys";
      })

      # NOTE: the version of abc used here is synchronized with
      # the one in the yosys Makefile of the version above;
      # keep them the same for quality purposes.
      (super.fetchFromGitHub {
        owner  = "berkeley-abc";
        repo   = "abc";
        rev    = "3709744c60696c5e3f4cc123939921ce8107fe04";
        sha256 = "18a9cjng3qfalq8m9az5ck1y5h4l2pf9ycrvkzs9hn82b1j7vrax";
        name   = "yosys-abc";
      })
    ];
    buildInputs = oa.buildInputs ++ [ super.zlib ];
  });
  nextpnr = super.nextpnr.overrideAttrs(oa: rec {
    name = "nextpnr-${version}";
    version = "2019-07-22";
    src = super.fetchFromGitHub {
      owner  = "yosyshq";
      repo   = "nextpnr";
      rev    = "ba050c21b94e816f9dd69f69b23ad5105858f401";
      sha256 = "1wxsv1lcbi6bvv5vryvjz9mj530iva85wh6b6pvnfff2i4yc3p9q";
    };
    buildInputs = oa.buildInputs ++ [ super.eigen ];
    cmakeFlags = oa.cmakeFlags ++ [ "-DUSE_OPENMP=ON" ];
  });
  icestorm = super.icestorm.overrideAttrs(oa: rec {
    name = "icestorm-${version}";
    version = "2019-07-03";
    src = super.fetchFromGitHub {
      owner  = "cliffordwolf";
      repo   = "icestorm";
      rev    = "792cef084a751e32f541332feb4905f8e49e9943";
      sha256 = "115qmgcz5ndw4z8ivk1cdlz6i2dzhq195gr8y4fjrjcb5jlacz23";
    };
  });
  trellis = super.trellis.overrideAttrs(oa: rec {
    name = "trellis-${version}";
    version = "2019-07-18";
    srcs = [
      (super.fetchFromGitHub {
         owner  = "symbiflow";
         repo   = "prjtrellis";
         rev    = "b27c0da5d20a4c105fe9be2b5f8d859316613f44";
         sha256 = "12jcs64agv5yhqq4zwjp2vd9y248608hz1gj187g1cfqrv0yc8d5";
         name   = "trellis";
       })
      (super.fetchFromGitHub {
        owner  = "symbiflow";
        repo   = "prjtrellis-db";
        rev    = "b4d626b6402c131e9a035470ffe4cf33ccbe7986";
        sha256 = "0k26lq6c049ja8hhqcljwjb1y5k4gcici23l2n86gyp83jr03ilx";
        name   = "database";
      })
    ];
  });

  llvm_7 = super.llvm_7.overrideAttrs(oa: {
    name = oa.name + "-riscv";
    cmakeFlags = oa.cmakeFlags ++ ["-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=RISCV"];
  });
  rustc = super.rustc.overrideAttrs(oa: {
    patches = oa.patches ++ [ ./compilers/rustc-riscv32i.patch ];
  });
  rustPlatform = super.makeRustPlatform { inherit rustc; inherit (super) cargo; };
}