From 58300857db25b06311936346f45dbf9f2849caec Mon Sep 17 00:00:00 2001
From: Gustavo Massaccesi <gustavo@oma.org.ar>
Date: Thu, 2 Jul 2015 16:09:12 -0300
Subject: [PATCH] Fix bug in type propagation to avoid the reduction of mutable
 variables

This fixes the bug twice:
* Don't reduce mutable variables with a type to #t in a Boolean context.
* Don't record the type of mutable variables when a predicate is
     checked in a test condition.
---
 pkgs/racket-test-core/tests/racket/optimize.rktl | 5 +++++
 racket/src/racket/src/optimize.c                 | 4 +++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/pkgs/racket-test-core/tests/racket/optimize.rktl b/pkgs/racket-test-core/tests/racket/optimize.rktl
index d8513e43da..6d63c4b603 100644
--- a/pkgs/racket-test-core/tests/racket/optimize.rktl
+++ b/pkgs/racket-test-core/tests/racket/optimize.rktl
@@ -1702,6 +1702,11 @@
            '(lambda (x) (not (if x #f #t))))
 (test-comp '(lambda (x) (let ([z 2]) (not (if x #f z))))
            '(lambda (x) (let ([z 2]) (not (if x #f #t)))))
+(test-comp '(lambda (z) (when (pair? z) #f))
+           '(lambda (z) (when (pair? z) (not z))))
+(test-comp '(lambda (z) (when (pair? z) (set! z #f) #f))
+           '(lambda (z) (when (pair? z) (set! z #f) (not z)))
+           #f)
 
 (test-comp '(lambda (x) (if x x #f))
            '(lambda (x) x))
diff --git a/racket/src/racket/src/optimize.c b/racket/src/racket/src/optimize.c
index 211b1e20be..dbf4062ade 100644
--- a/racket/src/racket/src/optimize.c
+++ b/racket/src/racket/src/optimize.c
@@ -4019,6 +4019,7 @@ static void add_types(Scheme_Object *t, Optimize_Info *info, int fuel)
     Scheme_App2_Rec *app = (Scheme_App2_Rec *)t;
     if (SCHEME_PRIMP(app->rator)
         && SAME_TYPE(SCHEME_TYPE(app->rand), scheme_local_type)
+        && !optimize_is_mutated(info, SCHEME_LOCAL_POS(app->rand))
         && relevant_predicate(app->rator)) {
       /* Looks like a predicate on a local variable. Record that the
          predicate succeeded, which may allow conversion of safe
@@ -7400,7 +7401,8 @@ Scheme_Object *scheme_optimize_expr(Scheme_Object *expr, Optimize_Info *info, in
 
       delta = optimize_info_get_shift(info, pos);
 
-      if (context & OPT_CONTEXT_BOOLEAN) {
+      if ((context & OPT_CONTEXT_BOOLEAN)
+          && !optimize_is_mutated(info, pos + delta)) {
         Scheme_Object *pred;
         pred = optimize_get_predicate(pos + delta, info);
         if (pred) {