PR 9729

svn: r11567

collects/scheme/private/contract.ss

@@ -1277,6 +1277,7 @@ improve method arity mismatch contract violation error messages?
            (null? x)
            (number? x)
            (regexp? x)
+           (prefab-struct-key x) ;; this cannot be last, since it doesn't return just #t
            (and (pair? x)
                 (printable? (car x))
                 (printable? (cdr x)))

collects/tests/mzscheme/contract-test.ss

@@ -4524,6 +4524,9 @@ so that propagation occurs.
   (test-flat-contract 'false/c #f #t)
   (test/spec-passed 'any/c '(contract any/c 1 'pos 'neg))
   (test-flat-contract 'printable/c (vector (cons 1 (box #f))) (lambda (x) x))
+  (let ()
+    (define-struct s (a b) #:prefab)
+    (test-flat-contract 'printable/c (make-s 1 2) (λ (x) x)))
   (test-flat-contract '(symbols 'a 'b 'c) 'a 'd)
   (test-flat-contract '(one-of/c (expt 2 65)) (expt 2 65) 12)
   (test-flat-contract '(one-of/c '#:x '#:z) '#:x '#:y)