anchor.diff:        await dillLoadedData.buildOutlines();
       }
       if (userBuilders.isEmpty) userBuilders = null;
  +    return newDillLibraryBuilders;
     }
   
     /// Compute which libraries to output and which (previous) errors/warnings we
  
positive.code:     if (userCode != null) {
        Set<Uri> uris = new Set<Uri>.from(userCode.loader.builders.keys);
        uris.removeAll(dillLoadedData.loader.builders.keys);
        invalidatedUris.addAll(uris);
      }
    }
  
negative.code:         userCode.loader.builders.clear();
          userCode = userCodeOld;
        } else {
          previousSourceBuilders = await convertSourceLibraryBuildersToDill();
        }
  
        // Output result.
  