From 0112367891b420e7951f2a224f4338c8f1ba1611 Mon Sep 17 00:00:00 2001
From: Taylor R Campbell <campbell@mumble.net>
Date: Sun, 2 Dec 2018 01:35:04 +0000
Subject: [PATCH] pp is busted on circular data structures.

---
 tests/check.scm           |  1 +
 tests/runtime/test-pp.scm | 83 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)
 create mode 100644 tests/runtime/test-pp.scm

diff --git a/tests/check.scm b/tests/check.scm
index 5c16aeb46..53dd887b9 100644
--- a/tests/check.scm
+++ b/tests/check.scm
@@ -83,6 +83,7 @@ USA.
     "runtime/test-optional.bin"
     "runtime/test-optional.com"
     ("runtime/test-parametric-predicate" (runtime parametric-predicate))
+    "runtime/test-pp"
     "runtime/test-predicate"
     ("runtime/test-predicate-dispatch" (runtime predicate-dispatch))
     "runtime/test-process"
diff --git a/tests/runtime/test-pp.scm b/tests/runtime/test-pp.scm
new file mode 100644
index 000000000..300a7728a
--- /dev/null
+++ b/tests/runtime/test-pp.scm
@@ -0,0 +1,83 @@
+#| -*-Scheme-*-
+
+Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
+    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
+    2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
+    2017, 2018 Massachusetts Institute of Technology
+
+This file is part of MIT/GNU Scheme.
+
+MIT/GNU Scheme is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or (at
+your option) any later version.
+
+MIT/GNU Scheme is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with MIT/GNU Scheme; if not, write to the Free Software
+Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
+USA.
+
+|#
+
+;;;; Tests of pretty-printer
+
+(declare (usual-integrations))
+
+(define (carefully procedure if-overflow if-timeout)
+  (let ((thread #f)
+        (mutex (make-thread-mutex))
+        (condvar (make-condition-variable))
+        (gc-env (->environment '(runtime garbage-collector))))
+    (define (start-it)
+      (with-thread-mutex-lock mutex
+        (lambda ()
+          (do () (thread)
+            (condition-variable-wait! condvar mutex))))
+      (let ((default/stack-overflow (access default/stack-overflow gc-env)))
+        (define (give-up)
+          (if (eq? thread (current-thread))
+              (exit-current-thread (if-overflow))
+              (default/stack-overflow)))
+        (call-with-current-continuation
+          (lambda (abort)
+            (fluid-let (((access hook/stack-overflow gc-env)
+                         (lambda () (within-continuation abort give-up))))
+              (exit-current-thread (procedure)))))))
+    (define (stop-it)
+      (assert thread)
+      (signal-thread-event thread
+                           (lambda ()
+                             (exit-current-thread (if-timeout)))))
+    (let ((t (create-thread #f start-it)))
+      (with-thread-mutex-lock mutex
+        (lambda ()
+          (set! thread t)
+          (condition-variable-broadcast! condvar))))
+    (let ((result #f))
+      (define (done-it thread* value)
+        (assert (eq? thread* thread))
+        (set! result value))
+      (join-thread thread done-it)
+      (let ((timer))
+        (dynamic-wind
+          (lambda () (set! timer (register-timer-event 1000 stop-it)))
+          (lambda () (do () (result) (suspend-current-thread)))
+          (lambda () (deregister-timer-event (set! timer))))))))
+
+(define-test 'circular
+  (lambda ()
+    (define (doit)
+      (let ((c (cons 0 0)))
+        (set-car! c c)
+        (set-cdr! c c)
+        (call-with-output-string (lambda (p) (pp c p)))))
+    (expect-failure
+     (lambda ()
+       (assert-eqv
+        (carefully doit (lambda () 'stack-overflow) (lambda () 'timeout))
+        "#0=(#0# . #0#)")))))
-- 
2.25.1