catching tail-calling bug. Appears the siuation is: if the tail call is a values, but there's some let bindings that we need to wipe out, we haven't done the proper cleanup.

tests/more-tests/isolating-bug.expected

@@ -0,0 +1,3 @@
+#<procedure:make-swf>
+#<procedure:swf?>
+#<procedure:swf-f>

tests/more-tests/isolating-bug.rkt

@@ -0,0 +1,29 @@
+#lang planet dyoo/whalesong/base
+(require (for-syntax racket/base
+                     syntax/struct))
+
+
+(define-syntax (my-define-struct stx)
+  (syntax-case stx ()
+    [(_ name (fields ...) kw ...)
+     (with-syntax ([(names ...)
+                    (build-struct-names #'name
+                                        (syntax->list #'(fields ...))
+                                        #f
+                                        #f)])
+       (with-syntax ([cnstr (syntax-case #'(names ...) ()
+                              [(struct:name-id constructor misc ...)
+                               #'constructor])])
+         #'(begin
+             (define-values (names ...)
+               (let ()
+                 (begin
+                   (define-struct name (fields ...) kw ...)
+                   (let ([cnstr (lambda args
+                                  (apply cnstr args))])
+                     (values names ...))))))))]))
+
+(my-define-struct swf (f) #:mutable)
+make-swf
+swf?
+swf-f