Magento – Show out of stock simple products swatches in configurable (M2.2.4)

Warning, using setSkipSaleableCheck(true) appears to have an additional effect of showing disabled products in the dropdown.

The function which is affected by this setting is in Mage_Catalog_Block_Product_View_Type_Configurable:

public function getAllowProducts()
{
    if (!$this->hasAllowProducts()) {
        $products = array();
        $skipSaleableCheck = Mage::helper('catalog/product')->getSkipSaleableCheck();
        $allProducts = $this->getProduct()->getTypeInstance(true)
            ->getUsedProducts(null, $this->getProduct());
        foreach ($allProducts as $product) {
            if ($product->isSaleable() || $skipSaleableCheck) {
                $products[] = $product;
            }
        }
        $this->setAllowProducts($products);
    }
    return $this->getData('allow_products');
}

if ($product->isSaleable() || $skipSaleableCheck) will therefore always be true

I am yet to dig through the isSaleable() function to determine exactly where this occurs (maybe someone can confirm) but my guess is that it includes a check against the products status which is missed if the skipSaleableCheck is set to true.

Set the simple product Visibility (Catalog->Manage Product->"Select Product"->General) to "Not Visible Individually". Place the simple product to "In Stock" and add Quantity. (Simple products will not show on the front end)

The Configurable product should now show the available simple products. A configurable products inventory is based off the simple product's inventory.

Hope this helps.