anchor.diff: -{ lib, stdenv, fetchFromGitHub
  -, python3, boost
  -, cmake
  -}:
  +{ lib, stdenv, fetchFromGitHub, python3, boost, cmake }:
   
  -stdenv.mkDerivation rec {
  +let
  +  rev = "03e0070f263fbe31c247de61d259544722786210";
  +  # git describe --tags
  +  realVersion = "1.0-532-g${builtins.substring 0 7 rev}";
  +in stdenv.mkDerivation rec {
     pname = "trellis";
  -  version = "2021.07.06";
  -
  -  # git describe --tags
  -  realVersion = with lib; with builtins;
  -    "1.0-482-g${substring 0 7 (elemAt srcs 0).rev}";
  +  version = "2021-09-01";
   
     srcs = [
       (fetchFromGitHub {
          owner  = "YosysHQ";
          repo   = "prjtrellis";
  -       rev    = "dff1cbcb1bd30de7e96f8a059f2e19be1bb2e44d";
  -       sha256 = "1gbrka9gqn124shx448aivbgywyp30zyjwfazr7v49lhrl7d46lb";
  +       inherit rev;
  +       sha256 = "joQMsjVj8d3M3IaqOkfVQ1I5qPDM8HHJiye+Ak8f3dg=";
          name   = "trellis";
        })
   
       (fetchFromGitHub {
         owner  = "YosysHQ";
         repo   = "prjtrellis-db";
  -      rev    = "0ee729d20eaf9f1e0f1d657bc6452e3ffe6a0d63";
  -      sha256 = "0069c98bb4wilxz21snwc39yy0rm7ffma179djyz57d99p0vcfkq";
  +      rev    = "fdf4bf275a7402654bc643db537173e2fbc86103";
  +      sha256 = "eDq2wU2pnfK9bOkEVZ07NQPv02Dc6iB+p5GTtVBiyQA=";
         name   = "trellis-database";
       })
     ];
  
positive.code:       to provide sufficient information to develop a free and
        open Verilog to bitstream toolchain for these devices.
      '';
      homepage    = "https://github.com/SymbiFlow/prjtrellis";
      license     = lib.licenses.isc;
      maintainers = with maintainers; [ q3k thoughtpolice emily ];
      platforms   = lib.platforms.all;
    };
  }
  
negative.code:   nativeBuildInputs = [ cmake python3 ];
    cmakeFlags = [
      "-DCURRENT_GIT_VERSION=${realVersion}"
    ];
  
    preConfigure = ''
      rmdir database && ln -sfv ${builtins.elemAt srcs 1} ./database
  
      cd libtrellis
    '';
  
  