Recursive lcons force bug (keep-if*, remove-if*).

* lib.c (rem_lazy_func): Do not access the cdr field of
the lcons that we are in the middle of forcing!

2 files changed, 10 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 7d666f83..5b68c559 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2015-05-13  Kaz Kylheku  <kaz@kylheku.com>
 
+	Recursive lcons force bug (keep-if*, remove-if*).
+
+	* lib.c (rem_lazy_func): Do not access the cdr field of
+	the lcons that we are in the middle of forcing!
+
+2015-05-13  Kaz Kylheku  <kaz@kylheku.com>
+
 	* place.tl (define-modify-macro): New macro.
 
 	* lisplib.c (set_place_dlt_entries): Add define-modify-macro.
diff --git a/lib.c b/lib.c
index a1dd429e..28e58240 100644
--- a/lib.c
+++ b/lib.c
@@ -1153,7 +1153,9 @@ static val rem_lazy_rec(val obj, val list, val env, val func);
 static val rem_lazy_func(val env, val lcons)
 {
   cons_bind (pred, list, env);
-  return cdr(rplacd(lcons, rem_lazy_rec(pred, list, env, lcons_fun(lcons))));
+  val rest = rem_lazy_rec(pred, list, env, lcons_fun(lcons));
+  rplacd(lcons, rem_lazy_rec(pred, list, env, lcons_fun(lcons)));
+  return rest;
 }
 
 static val rem_lazy_rec(val pred, val list, val env, val func)