Chance the Rapper is a study in redundancy ... this according to none other than Dionne Warwick, and her words sent Chance into orbit!!!

Dionne tweeted Saturday night, "If you are very obviously a rapper why did you put it in your stage name? I cannot stop thinking about this."

Solid point, Dionne. Chance flipped out, but not because of Dionne's note. He fired back, "Sorry I'm still freaking out that u know who I am. This is amazing!"

Dionne, who's a big fan of Chance and loves "Holy," responded, "Of course I know you.  You're THE rapper. Let's rap together." Our take ... THAT WOULD BE AWESOME!!!

But, Dionne wasn't done ... after calling herself "Dionne the Singer," she wondered, "The Weeknd is next. Why?  It's not even spelled correctly?"

He then responded ... "I got roasted by Dionne Warwick and I feel honored! You just made my day."