Problem showing configurable items correctly

[brosenberger]

Precondition

• additionally module https://github.com/karliuka/m2.SmartCategoryConfigurable installed
• create category with special price filter and option replace on configurable set to true
• create a configurable (visibility catalog, search) with multiple configurated simple products (visibility individually not visible)

Action

• add special price for one of the simple products of the configurable

Expected

• the configurable product is shown in the given smart category in the frontend

Result

• the configurable product is not shown in the given smart category

Current findings

• within the catalog_product_category table only the simple product is added to the smart category and therefor the normal category_product_indexer does not add it to the index as the simple product is not visible individually
• the arrays $postedProducts and $matchingProducts (\Faonni\SmartCategory\Model\Indexer\IndexBuilder::updateRuleProductData) differ but deleteIds and insertIds are both empty to due the array_diff method (both product arrays have the following structure: [productId1 => 1, productId2 => 1, ... ]. Therefore i think the correct solution would be to change the php method array_diff with array_diff_key to gain the differences in both arrays in
  

  m2.SmartCategory/Model/Indexer/IndexBuilder.php

  Line 299 in 7b97acb

  $deleteIds = array_diff($postedProducts, $matchingProducts);

  but i am not quite sure if the current check was intentional

[pinguluk]

I see that he made an extension for that:
https://github.com/karliuka/m2.SmartCategoryConfigurable