Adding 'is_saleable' attribute to sort of product collection causes exception and adding 'is_salable' has no effect

[dnadle]

In Magento\Catalog\Model\ResourceModel\Product\Collection, addAttributeToSort() has the following lines:

        } elseif ($attribute == 'is_saleable') {
            $this->getSelect()->order("is_saleable " . $dir);
            return $this;
        }

But the generated SQL query selects stock_status_index.stock_status as 'is_salable', not 'is_saleable'. So adding 'is_saleable' causes an SQL exception and since 'is_salable' is not a product attribute, it silently fails to be added to the SQL statement.

Preconditions

1. Magento CE 2.1.2

Steps to reproduce

1. Modify a collection prior to load with $collection->addAttributeToSort("is_saleable").

Expected result

1. The product stock_status is included in the query sort clause.

Actual result

1. Exceptions:

2 exception(s):
Exception #0 (Zend_Db_Statement_Exception): SQLSTATE[42S22]: Column not found: 1054 Unknown column 'is_saleable' in 'order clause', query was: SELECT `e`.*, `cat_index`.`position` AS `cat_index_position`, `price_index`.`price`, `price_index`.`tax_class_id`, `price_index`.`final_price`, IF(price_index.tier_price IS NOT NULL, LEAST(price_index.min_price, price_index.tier_price), price_index.min_price) AS `minimal_price`, `price_index`.`min_price`, `price_index`.`max_price`, `price_index`.`tier_price`, `stock_status_index`.`stock_status` AS `is_salable`, IF(at_name.value_id > 0, at_name.value, at_name_default.value) AS `name` FROM `catalog_product_entity` AS `e`
 INNER JOIN `catalog_category_product_index` AS `cat_index` ON cat_index.product_id=e.entity_id AND cat_index.store_id=1 AND cat_index.visibility IN(2, 4) AND cat_index.category_id='245'
 INNER JOIN `catalog_product_index_price` AS `price_index` ON price_index.entity_id = e.entity_id AND price_index.website_id = '1' AND price_index.customer_group_id = 0
 LEFT JOIN `cataloginventory_stock_status` AS `stock_status_index` ON e.entity_id = stock_status_index.product_id AND stock_status_index.website_id = 0 AND stock_status_index.stock_id = 1
 INNER JOIN `search_tmp_584f50b9a23f51_22855701` AS `search_result` ON e.entity_id = search_result.entity_id
 LEFT JOIN `catalog_product_entity_varchar` AS `at_name_default` ON (`at_name_default`.`entity_id` = `e`.`entity_id`) AND (`at_name_default`.`attribute_id` = '70') AND `at_name_default`.`store_id` = 0
 LEFT JOIN `catalog_product_entity_varchar` AS `at_name` ON (`at_name`.`entity_id` = `e`.`entity_id`) AND (`at_name`.`attribute_id` = '70') AND (`at_name`.`store_id` = 1) ORDER BY `is_saleable` DESC, `name` ASC
 LIMIT 32
Exception #1 (PDOException): SQLSTATE[42S22]: Column not found: 1054 Unknown column 'is_saleable' in 'order clause'

Workaround

Modify the collection instead with $collection->getSelect()->order('is_salable');

[magento-engcom-team]

@dnadle, thank you for your report.
We've created internal ticket(s) MAGETWO-81297 to track progress on the issue.