What is the general rule for declining (sarf) words that end in a prolonged alif (alif mamdudah) in the Qur'an?

The condition for not declining nouns ending with a prolonged alif (alif mamdudah) is that the hamza must be an extra letter added for feminization (e.g., hamra’ - red). However, if the hamza is original, it does not prevent the noun from being declined (e.g., asma’ - names, abna’ - sons, sama’ - sky). These words have been vocalized with tanween in the Holy Quran. The rule is that the alif of feminization absolutely prevents nouns from being declined, whether it is prolonged or shortened.