define-struct/contract members are always annotated "no bound occurrences"

Given:

#lang racket/base

(require racket/contract)

(struct plain (a b))
(plain 1 2)

(define-struct/contract contracted ([a any/c] [b any/c]))
(contracted 1 2)

The a and b members of contracted (but not of plain) are annotated "no bound occurrences".

This is true in both Dr Racket and Racket Mode. The presentation is more obvious in Racket Mode, because by default it is configured to show unused identifiers and requires with a strikeout font (as well as showing the mouseover text). Whereas in Dr Racket you would not notice unless you mouse hover.^1

^1: In general: The fact that Racket Mode more strongly "surfaces in the UI" annotations about unused items, with a configurable font, is for some users a positive feature. At the same time, that means it is going to surface more "edge" and/or "interesting" cases, like this -- fortunately or unfortunately.

Reproduce the reported example in DrRacket and Racket Mode, comparing the annotations on the plain and contracted structures. Trace how the define-struct/contract members are classified for bound occurrences; done means the contracted members no longer show "no bound occurrences" while the plain-structure behavior remains correct.