anchor.diff:    spdlog_1 = generic {
       version = "1.9.2";
       sha256 = "sha256-GSUdHtvV/97RyDKy8i+ticnSlQCubGGWHg4Oo+YAr8Y=";
  +    patches = [
  +      # glibc 2.34 compat
  +      (fetchpatch {
  +        url = "https://github.com/gabime/spdlog/commit/d54b8e89c058f3cab2b32b3e9a2b49fd171d5895.patch";
  +        sha256 = "sha256-pb7cREF90GXb5Mbs8xFLQ+eLo6Xum13/xYa8JUgJlbI=";
  +      })
  +    ];
     };
   
     spdlog_0 = generic {
  
positive.code: { lib, stdenv, fetchFromGitHub, cmake, fmt_8, fetchpatch }:
  
  let
    generic = { version, sha256 }:
      stdenv.mkDerivation {
        pname = "spdlog";
        inherit version;
  
negative.code:         inherit sha256;
        };
  
        inherit patches;
  
        nativeBuildInputs = [ cmake ];
        # spdlog <1.3 uses a bundled version of fmt
  