anchor.diff:      isFcitxEngine = bool;
       isIbusEngine = bool;
       isGutenprint = bool;
  +    badPlatforms = platforms;
     };
   
     checkMetaAttr = k: v:
  
positive.code:       { valid = false; reason = "blacklisted"; errormsg = "has a blacklisted license (‘${showLicense attrs.meta.license}’)"; }
      else if !allowBroken && attrs.meta.broken or false then
        { valid = false; reason = "broken"; errormsg = "is marked as broken"; }
      else if !allowUnsupportedSystem && !allowBroken && attrs.meta.platforms or null != null && !(checkPlatform attrs) then
        { valid = false; reason = "broken"; errormsg = "is not supported on ‘${hostPlatform.config}’"; }
      else if !(hasAllowedInsecure attrs) then
        { valid = false; reason = "insecure"; errormsg = "is marked as insecure"; }
  
negative.code:   checkMeta = meta: if shouldCheckMeta then lib.remove null (lib.mapAttrsToList checkMetaAttr meta) else [];
  
    checkPlatform = attrs:
      (!(attrs ? meta.platforms) || lib.any (lib.meta.platformMatch hostPlatform) attrs.meta.platforms) &&
      (!(attrs ? meta.badPlatforms && lib.any (lib.meta.platformMatch hostPlatform) attrs.meta.badPlatforms));
  
    # Check if a derivation is valid, that is whether it passes checks for
    # e.g brokenness or license.
  