[RPG] use Pact Magic spell slots gained on a short rest to gain sorcery points

dnd-5emulti-classingsorcererwarlock

I'm planning on multi-classing in Warlock as a Sorcerer in 5e. I'd like to be able to use my Warlock spell slots from Pact Magic (that I regain on a short rest) to gain sorcery points.

I'm inclined to believe the answer to this question is "Yes", because the Font of Magic feature does not specify that the slots expended need be Sorcerer spell slots or even Spellcasting spell slots. Although it does seem to be RAW, I find it hard to believe that this was RAI, because it essentially copies the Sorcerer capstone with three levels in Warlock. Does anyone know if there's an official ruling as to whether or not this is allowed?

Here's the relevant rule:

Converting a Spell Slot to Sorcery Points. As a bonus action on your turn, you can expend one spell slot and gain a number of sorcery points equal to the slot’s level.

Best Answer

Yes, Flexible Casting doesn't specify where the spell slot comes from, just that you expend one to gain points. This means that you can expend a spell slot that you have from Pact Magic to satisfy its requirement, and thus gain sorcery points from it.

And yes, this has been confirmed as the correct reading by Jeremy Crawford, the lead rules designer for D&D 5e, for exactly the use you're asking about (though Crawford's tweets are no longer considered official rulings):

Bill Cavalier @dungeonbastard · 6 May 2015
@JeremyECrawford Can a warlock/sorcerer covert warlock spell slots to sorcery points?

Jeremy Crawford‏ @JeremyECrawford · 6 May 2015
The sorcerer's Flexible Casting feature is omnivorous, able to turn spell slots from any class into sorcery points.

Bill Cavalier‏ @dungeonbastard · 6 May 2015
@JeremyECrawford The use case is: convert warlock slots to sorc points, short rest, regain warlock slots. Turning a short rest asset to long

Jeremy Crawford‏ @JeremyECrawford · 6 May 2015
@dungeonbastard Yep, that works. Similarly, a paladin/warlock can use warlock slots for Divine Smite. Warlocks have so few slots on purpose!