#14020-Cart-Sales-Rule-with-negated-condition-over-special-price-does-not-work-for-configurable-products.

Use configurable product`s children for shopping cart rules validation
for cases when attribute exists for children only (E.g. special_price)

Author: novikor

app/code/Magento/SalesRule/Model/Rule/Condition/Product.php

@@ -5,10 +5,14 @@
  */
 namespace Magento\SalesRule\Model\Rule\Condition;
 
+use Magento\ConfigurableProduct\Model\Product\Type\Configurable;
+
 /**
  * Product rule condition data model
  *
  * @author Magento Core Team <[email protected]>
+ *
+ * @method string getAttribute()
  */
 class Product extends \Magento\Rule\Model\Condition\Product\AbstractProduct
 {
@@ -26,20 +30,47 @@ protected function _addSpecialAttributes(array &$attributes)
         $attributes['quote_item_row_total'] = __('Row total in cart');
     }
 
+    /**
+     * @param \Magento\Framework\Model\AbstractModel $model
+     *
+     * @return \Magento\Catalog\Api\Data\ProductInterface|\Magento\Catalog\Model\Product
+     * @throws \Magento\Framework\Exception\NoSuchEntityException
+     */
+    protected function getProductToValidate(\Magento\Framework\Model\AbstractModel $model)
+    {
+        /** @var \Magento\Catalog\Model\Product $product */
+        $product = $model->getProduct();
+        if (!$product instanceof \Magento\Catalog\Model\Product) {
+            $product = $this->productRepository->getById($model->getProductId());
+        }
+
+        $attrCode = $this->getAttribute();
+
+        /* Check for attributes which are not available for configurable products */
+        if ($product->getTypeId() == Configurable::TYPE_CODE && !$product->hasData($attrCode)) {
+            /** @var \Magento\Catalog\Api\Data\ProductInterface $childProduct */
+            $childProduct = current($model->getChildren())->getProduct();
+            if ($childProduct->hasData($attrCode)) {
+                $product = $childProduct;
+            }
+        }
+
+        return $product;
+    }
+
     /**
      * Validate Product Rule Condition
      *
      * @param \Magento\Framework\Model\AbstractModel $model
+     *
      * @return bool
+     * @throws \Magento\Framework\Exception\NoSuchEntityException
      */
     public function validate(\Magento\Framework\Model\AbstractModel $model)
     {
         //@todo reimplement this method when is fixed MAGETWO-5713
         /** @var \Magento\Catalog\Model\Product $product */
-        $product = $model->getProduct();
-        if (!$product instanceof \Magento\Catalog\Model\Product) {
-            $product = $this->productRepository->getById($model->getProductId());
-        }
+        $product = $this->getProductToValidate($model);
 
         $product->setQuoteItemQty(
             $model->getQty()
@@ -49,9 +80,8 @@ public function validate(\Magento\Framework\Model\AbstractModel $model)
             $model->getBaseRowTotal()
         );
 
-        $attrCode = $this->getAttribute();
 
-        if ('category_ids' == $attrCode) {
+        if ('category_ids' == $this->getAttribute()) {
             return $this->validateAttribute($this->_getAvailableInCategories($product->getId()));
         }