From 32ad0656a686680f5c8f3796046c405b9c2aa000 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Thu, 30 Aug 2007 18:52:58 +0000
Subject: [PATCH] fix bytecode optimizer bug in eliminating let[rec]-values
 bindings of (values) to zero variables

svn: r7229
---
 src/mzscheme/src/syntax.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/mzscheme/src/syntax.c b/src/mzscheme/src/syntax.c
index 4ddbe5e62f..549bce2e4e 100644
--- a/src/mzscheme/src/syntax.c
+++ b/src/mzscheme/src/syntax.c
@@ -2770,7 +2770,7 @@ scheme_optimize_lets(Scheme_Object *form, Optimize_Info *info, int for_inline)
     if ((pre_body->count != 1)
         && is_values_apply(value)
         && scheme_omittable_expr(value, pre_body->count)) {
-      if (!pre_body->count && !i && (head->num_clauses > 1)) {
+      if (!pre_body->count && !i) {
         /* We want to drop the clause entirely, but doing it
            here messes up the loop for letrec. So wait and 
            remove it at the end. */
@@ -2947,7 +2947,10 @@ scheme_optimize_lets(Scheme_Object *form, Optimize_Info *info, int for_inline)
   }
 
   body = scheme_optimize_expr(body, body_info);
-  pre_body->body = body;
+  if (head->num_clauses)
+    pre_body->body = body;
+  else
+    head->body = body;
   info->size += 1;
 
   info->single_result = body_info->single_result;