Singular "pant" has recently-ish become accepted fashion industry jargon: "Our spring collection includes a khaki pant and a capri pant". I've started to see it creep from there into everyday language.
Typical example is the word _water_. It is noncount except when talking about types of water. E.g., this year we introduced a vitamin water and an energy water to our line of beverages. By extension, you can pluralize it: we introduced two new waters this year.
I don't disagree that pants might be slowly becoming countable, just noting that the particular verbiage of "a capri pant" or whatever can be produced using the usual rules.