From f9c71551ad5c233c3ffe19900356f0ecba4f4d38 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sun, 15 May 2016 22:29:59 -0700
Subject: Bugfix: recycled conses play nice with gen GC.

* lib.c (cons): When we recycle a cons, it could
be already in the mature generation. In that case,
baby objects stored in its car or cdr violate the
integrity of the heap. We must hint about this
to the garbage collector. Test case:
./txr --gc-debug -p "(list* 'foo (zip
'(a) (repeat '((gensym)))))"
---
 lib.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib.c b/lib.c
index abcce6ba..64a22b68 100644
--- a/lib.c
+++ b/lib.c
@@ -2501,6 +2501,9 @@ val cons(val car, val cdr)
   if (recycled_conses) {
     obj = recycled_conses;
     recycled_conses = recycled_conses->c.cdr;
+#if CONFIG_GEN_GC
+    gc_mutated(obj);
+#endif
   } else {
     obj = make_obj();
     obj->c.type = CONS;
-- 
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