anchor.diff:    filterOverrides = defs:
       let
         defaultPrio = 100;
  -      getPrio = def: if def.config._type or "" == "override" then def.config.priority else defaultPrio;
  +      getPrio = def: if def.value._type or "" == "override" then def.value.priority else defaultPrio;
         min = x: y: if x < y then x else y;
         highestPrio = fold (def: prio: min (getPrio def) prio) 9999 defs;
  -      strip = def: if def.config._type or "" == "override" then def // { config = def.config.content; } else def;
  +      strip = def: if def.value._type or "" == "override" then def // { value = def.value.content; } else def;
       in concatMap (def: if getPrio def == highestPrio then [(strip def)] else []) defs;
   
     /* Hack for backward compatibility: convert options of type
  
positive.code:           throw "The option `${showOption loc}' is used but not defined."
          else
            fold (def: res:
              if opt.type.check def.config then res
              else throw "The option value `${showOption loc}' in `${def.file}' is not a ${opt.type.name}.")
              (opt.type.merge (map (m: m.config) defsFinal)) defsFinal;
        # Finally, apply the ‘apply’ function to the merged
        # value.  This allows options to yield a value computed
        # from the definitions.
  
negative.code:                 (pushDownProperties (getAttr name m.config)))
              ) configs);
            nrOptions = count (m: isOption m.options) decls;
            # Process mkMerge and mkIf properties.
            defns' = concatMap (m:
              optionals (hasAttr name m.config)
                (map (m': { inherit (m) file; value = m'; }) (dischargeProperties (getAttr name m.config)))
              ) configs;
          in
            if nrOptions == length decls then
              let opt = fixupOptionType loc' (mergeOptionDecls loc' decls);
              in evalOptionValue loc' opt defns'
            else if nrOptions != 0 then
              let
                firstOption = findFirst (m: isOption m.options) "" decls;
  