nobu	2017-04-20 00:14:03 +0900 (Thu, 20 Apr 2017)

  New Revision: 58405

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=58405

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

  Modified files:
    trunk/vm_insnhelper.c
Index: vm_insnhelper.c
===================================================================
--- vm_insnhelper.c	(revision 58404)
+++ vm_insnhelper.c	(revision 58405)
@@ -3238,8 +3238,9 @@ static VALUE https://github.com/ruby/ruby/blob/trunk/vm_insnhelper.c#L3238
 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_th https://github.com/ruby/ruby/blob/trunk/vm_insnhelper.c#L3261
 	/* waiting for finish */
 	RUBY_VM_CHECK_INTS(th);
 	rb_thread_schedule();
-	return vm_once_dispatch(iseq, ic, th);
+	goto again;
     }
 }
 

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