From 8f20264a8333092cff780dd4755627a28e2c93ac Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Thu, 10 Jul 2014 14:11:46 +0100
Subject: [PATCH] fix marshaling of #'(....  . ()) to bytecode

---
 .../racket-test/tests/racket/stx.rktl         | 19 +++++++++++++++++++
 racket/src/racket/src/syntax.c                |  2 +-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/pkgs/racket-pkgs/racket-test/tests/racket/stx.rktl b/pkgs/racket-pkgs/racket-test/tests/racket/stx.rktl
index c898d546f0..35ddf188ba 100644
--- a/pkgs/racket-pkgs/racket-test/tests/racket/stx.rktl
+++ b/pkgs/racket-pkgs/racket-test/tests/racket/stx.rktl
@@ -1819,6 +1819,25 @@
   (define-syntax ++ (make-rename-transformer (datum->syntax #'here '+)))
   (test #f values (displayln-syntax-local-value/immediate ++)))
 
+;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Check that syntax structure is preserved precisely with
+;; #'(a . ()) as opposed to #'(a)
+
+(let ()
+  (define-values (i o) (make-pipe))
+  (write (compile #'#'(a)) o)
+  (close-output-port o)
+  (define s (parameterize ([read-accept-compiled #t])
+              (read i)))
+  (test #t null? (cdr (syntax-e (eval s)))))
+(let ()
+  (define-values (i o) (make-pipe))
+  (write (compile #'#'(a . ())) o)
+  (close-output-port o)
+  (define s (parameterize ([read-accept-compiled #t])
+              (read i)))
+  (test #t syntax? (cdr (syntax-e (eval s)))))
+
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (report-errs)
diff --git a/racket/src/racket/src/syntax.c b/racket/src/racket/src/syntax.c
index 99a3645c1d..ab0e7cc7c5 100644
--- a/racket/src/racket/src/syntax.c
+++ b/racket/src/racket/src/syntax.c
@@ -6611,7 +6611,7 @@ static Scheme_Object *extract_for_common_wrap(Scheme_Object *a, int get_mark, in
         else
           return SCHEME_CDR(v);
       }
-    } else if (!SCHEME_BOXP(v) && !SCHEME_VECTORP(v) && !SCHEME_HASHTRP(v) && !prefab_p(v)) {
+    } else if (!SCHEME_NULLP(v) && !SCHEME_BOXP(v) && !SCHEME_VECTORP(v) && !SCHEME_HASHTRP(v) && !prefab_p(v)) {
       /* It's atomic. */
       if (get_mark)
         return SCHEME_CDR(a);