Regression in type inference for uses of newly defined sub-type in polymorphic functions

What version of Racket are you using?

7.2

What program did you run?

#lang typed/racket/base

(struct (X) Wrap ([content : (Option X)]) #:transparent)
(define-new-subtype New-Int (Integer->New-Int Integer))

(: poly (∀ (X) (X → Any) (Wrap X) → Any))
(define (poly f xs) 'ignore)

(: mono : (New-Int → Any) (Wrap New-Int) → Any)
(define (mono f xs) (poly f xs))

What should have happened?

This program type-checks in 7.0. One of the following changes make the program type check in 7.2:

• Manually instantiate (inst poly New-Int)
• Define New-Int to just be an alias of Integer instead of sub type
• Change content's type from Option X to X or Listof X

If you got an error message, please include it here.

; Type Checker: Polymorphic function `poly' could not be applied to arguments:
; Argument 1:
;   Expected: (-> X Any)
;   Given:    (-> New-Int Any)
; Argument 2:
;   Expected: (Wrap X)
;   Given:    (Wrap New-Int)
; 
; Result type:     Any
; Expected result: Any
; 
;   in: (poly f xs)

Start by running the supplied #lang typed/racket/base program and inspect the type-checking failure at (poly f xs). Compare inference for Wrap New-Int and the Option X field with the behavior in Racket 7.0. Done means the program type-checks in the normal polymorphic call without manual instantiation or changing the subtype or field type.