Use the correct index for unsafe-Type-key

The unsafe operation didn't return the same result as
the safe operation, meaning any checks related to type keys
were giving the wrong result. As a result, some subtyping
clauses were not triggered.

original commit: 7907320733b6d29b2382e016c10888acbf4e1c67

pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/rep/rep-utils.rkt

@@ -356,7 +356,7 @@
 
 ;; NOTE: change these if the definitions above change, or everything will segfault
 (define-syntax-rule (unsafe-Rep-seq v) (unsafe-struct*-ref v 0))
-(define-syntax-rule (unsafe-Type-key v) (unsafe-struct*-ref v 1))
+(define-syntax-rule (unsafe-Type-key v) (unsafe-struct*-ref v 4))
 (provide unsafe-Rep-seq unsafe-Type-key)
 
 (define (Rep-values rep)

pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/types/subtype.rkt

@@ -448,7 +448,6 @@
          [((Base: _ _ _ #t) (Union: l2))
           #:when (eq? kt 'number)
           (and (memq s l2) A0)]
-         ;; this appears to never be called
          [((Union: l1) (Union: l2))
           #:when (and (eq? ks 'number) (eq? kt 'number))
           ;; l1 should be a subset of l2

pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/unit-tests/rep-tests.rkt

@@ -0,0 +1,23 @@
+#lang racket/base
+
+;; Tests for TR representation data structures such as types
+
+(require "test-utils.rkt"
+         rackunit
+         typed-racket/rep/rep-utils
+         typed-racket/rep/type-rep
+         typed-racket/types/abbrev)
+
+(provide tests)
+(gen-test-main)
+
+(define tests
+  (test-suite
+   "Tests for TR IR data structures"
+
+   ;; Make sure that unsafe operations return the same results as safe ones
+   (check-equal? (Rep-seq -String) (unsafe-Rep-seq -String))
+   (check-equal? (Rep-seq (-pair -String -String)) (unsafe-Rep-seq (-pair -String -String)))
+   (check-equal? (Type-key -String) (unsafe-Type-key -String))
+   (check-equal? (Type-key (-pair -String -String)) (unsafe-Type-key (-pair -String -String)))
+   ))