## Following the precedent of the Sage Advice Compendium, Whirlwind Attack will not allow you to make a melee spell attack ##

The section on [Melee Attacks][2] states:
>  A melee attack typically uses a handheld weapon such as a sword, a warhammer, or an axe. A typical monster makes a melee attack when it strikes with its claws, horns, teeth, tentacles, or other body part. **A few spells also involve making a melee attack**.

The section on [Opportunity Attacks][3] states:
> You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make **one melee attack** against the provoking creature.

So it would seem we could use melee spell for opportunity attacks; however, the [Sage Advice Compendium][1] has stated the following:
> Q. **Can you use a melee spell attack to make an opportunity
attack?**  
> A. You can’t if the spell attack is created by casting a spell. When a creature triggers an opportunity attack from you, you can use your reaction to make a melee attack against it. The opportunity attack doesn’t suddenly give you the ability to cast a spell, such as shocking grasp.

This is also showcased in this Q/A ("[Can I use a spell to make an Opportunity Attack?][4]")
Following this precedent we would also not be able to use the Whirlwind Attack feature to bypass the casting time requirement of a spell.  
Something allowing us to make a melee attack does not allow us to make a melee spell attack apparently because spells having their own casting time prevents this.


[1]: https://media.wizards.com/2019/dnd/downloads/SA-Compendium.pdf
[2]: https://www.dndbeyond.com/sources/basic-rules/combat#MeleeAttacks
[3]: https://www.dndbeyond.com/sources/basic-rules/combat#OpportunityAttacks
[4]: https://rpg.stackexchange.com/questions/108796