From f4c1d7ec032f3a1aabdc5e4cd0b0021b55f8d8e4 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Wed, 6 Aug 2014 08:46:51 +0100
Subject: [PATCH] racket/class: add missing check for #<unsafe-undefined>

When a superclass method is called before the superclass
is initialized, then all field accesses need to be guarded.

Robby found this one.
---
 .../racket-test/tests/racket/object.rktl      | 39 ++++++++++++-------
 .../collects/racket/private/class-undef.rkt   | 13 +++++--
 2 files changed, 33 insertions(+), 19 deletions(-)

diff --git a/pkgs/racket-pkgs/racket-test/tests/racket/object.rktl b/pkgs/racket-pkgs/racket-test/tests/racket/object.rktl
index ea856f62eb..070cc475bc 100644
--- a/pkgs/racket-pkgs/racket-test/tests/racket/object.rktl
+++ b/pkgs/racket-pkgs/racket-test/tests/racket/object.rktl
@@ -1927,6 +1927,11 @@
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; check error reporting for variable use before assignment
 
+(define (make-undefined-exn? name)
+  (lambda (exn)
+    (and (exn:fail:contract:variable? exn)
+         (eq? name (exn:fail:contract:variable-id exn)))))
+
 (let ()
   (define c%
     (class object%
@@ -1962,21 +1967,25 @@
       (field [s 1])
       (super-new)))
   
-  (err/rt-test (new d%) (lambda (exn)
-                          (and (exn:fail:contract:variable? exn)
-                               (eq? 'z (exn:fail:contract:variable-id exn)))))
-  (err/rt-test (new d!%) (lambda (exn)
-                           (and (exn:fail:contract:variable? exn)
-                                (eq? 'z (exn:fail:contract:variable-id exn)))))
-  (err/rt-test (new e%) (lambda (exn)
-                          (and (exn:fail:contract:variable? exn)
-                               (eq? 'z (exn:fail:contract:variable-id exn)))))
-  (err/rt-test (new d2%) (lambda (exn)
-                           (and (exn:fail:contract:variable? exn)
-                                (eq? 'f (exn:fail:contract:variable-id exn)))))
-  (err/rt-test (new e2%) (lambda (exn)
-                           (and (exn:fail:contract:variable? exn)
-                                (eq? 'f (exn:fail:contract:variable-id exn))))))
+  (err/rt-test (new d%) (make-undefined-exn? 'z))
+  (err/rt-test (new d!%) (make-undefined-exn? 'z))
+  (err/rt-test (new e%) (make-undefined-exn? 'z))
+  (err/rt-test (new d2%) (make-undefined-exn? 'f))
+  (err/rt-test (new e2%) (make-undefined-exn? 'f)))
+
+(let ()
+  (define c%
+    (class object%
+      (field [s #f])
+      (define/public (set-s)
+        (set! s #f))
+      (super-new)))
+  (define d%
+    (class c%
+      (inherit set-s)
+      (set-s)
+      (super-new)))
+  (err/rt-test (new d%) (make-undefined-exn? 's)))
 
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; check optimization to omit use-before-definition chaperone:
diff --git a/racket/collects/racket/private/class-undef.rkt b/racket/collects/racket/private/class-undef.rkt
index ac9060dfd1..f636a33ed8 100644
--- a/racket/collects/racket/private/class-undef.rkt
+++ b/racket/collects/racket/private/class-undef.rkt
@@ -124,10 +124,15 @@
             (free-identifier=? #'decl #'declare-this-escapes))
        ;; Any method call or explicit use of `this` means a field
        ;; might be accessed outside of the `class` declaration,
-       ;; so any initialization afterward is too late:
-       (begin
-         (when ready (set! init-too-late? #t))
-         (loop #'(begin . body)))]
+       ;; so `super-new` had better be done, and any initialization
+       ;; afterward is too late:
+       (or (and ready
+                (not super-new?) 
+                (report #'body)
+                #t)
+           (begin
+             (when ready (set! init-too-late? #t))
+             (loop #'(begin . body))))]
 
       [(begin '(decl) . body)
        (and (identifier? #'decl)