From f0e5e05609f6e1472573dcd9f94d82d60d56e03c Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Wed, 19 Apr 2017 15:14:03 +0000
Subject: [PATCH] fix infinite recursion

* vm_insnhelper.c (vm_once_dispatch): no guarantee that tail call
  is always optimized away.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58405 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 vm_insnhelper.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index d5b53314dc..a40a1c376e 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -3238,8 +3238,9 @@ static VALUE
 vm_once_dispatch(ISEQ iseq, IC ic, rb_thread_t *th)
 {
     rb_thread_t *const RUNNING_THREAD_ONCE_DONE = (rb_thread_t *)(0x1);
-    union iseq_inline_storage_entry *is = (union iseq_inline_storage_entry *)ic;
+    union iseq_inline_storage_entry *const is = (union iseq_inline_storage_entry *)ic;
 
+  again:
     if (is->once.running_thread == RUNNING_THREAD_ONCE_DONE) {
 	return is->once.value;
     }
@@ -3260,7 +3261,7 @@ vm_once_dispatch(ISEQ iseq, IC ic, rb_thread_t *th)
 	/* waiting for finish */
 	RUBY_VM_CHECK_INTS(th);
 	rb_thread_schedule();
-	return vm_once_dispatch(iseq, ic, th);
+	goto again;
     }
 }