Combat spurious retention in mapdo.

* lib.c (mapdo): gc_hint the list variable so that the list
march isn't entirely optimized into a register, leaving a
pointer to the top of the list on the stack.

1 files changed, 2 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index 580b2c2c..4700344e 100644
--- a/lib.c
+++ b/lib.c
@@ -6377,6 +6377,8 @@ val mapdo(val fun, val list)
 {
   list = nullify(list);
 
+  gc_hint(list);
+
   for (; list; list = cdr(list))
     funcall1(fun, car(list));