bug#13838: [PATCH] Fix duplicate removal of with-fluids

[David Kastrup <dak@gnu.org>]

The following code displayed #f:

(define a (make-fluid))
(define b (make-fluid))
(with-fluids ((a 3) (a 1) (b 2))
	     (display (fluid-ref b)))

In general, removing any duplicate that is not right at the end of the
(remaining) list will exhibit this problem.  The fluids and vals
arguments are modified in situ; the previous code only modified vals.
---
 libguile/fluids.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/libguile/fluids.c b/libguile/fluids.c
index f1c09cb..bd59e26 100644
--- a/libguile/fluids.c
+++ b/libguile/fluids.c
@@ -326,6 +326,8 @@ scm_i_make_with_fluids (size_t n, SCM *fluids, SCM *vals)
           {
             vals[i] = vals[j]; /* later bindings win */
             n--;
+            fluids[j] = fluids[n];
+            vals[j] = vals[n];
             break;
           }
   }
-- 
1.7.10.4