anchor.diff:          (map (drv: drv.crossDrv or drv) propagatedBuildInputs)
         ];
       in let
  -      pos' =
  -        if pos != null then
  -          pos
  -        else if attrs.meta.description or null != null then
  -          builtins.unsafeGetAttrPos "description" attrs.meta
  -        else
  -          builtins.unsafeGetAttrPos "name" attrs;
  -      pos'' = if pos' != null then "‘" + pos'.file + ":" + toString pos'.line + "’" else "«unknown-file»";
  -
  +      pos_str = if pos != null then "‘" + pos.file + ":" + toString pos.line + "’" else "«unknown-file»";
   
         remediation = {
           unfree = remediate_whitelist "Unfree";
  
positive.code:     , crossConfig ? null
      , meta ? {}
      , passthru ? {}
      , pos ? null # position used in error messages and for meta.position
      , separateDebugInfo ? false
      , outputs ? [ "out" ]
      , __impureHostDeps ? []
  
negative.code: 
        # Throw an error if trying to evaluate an non-valid derivation
        validityCondition =
               let v = checkValidity attrs;
               in if !v.valid
                 then throwEvalHelp (removeAttrs v ["valid"])
                 else true;
  