merge revision(s) 2e7e153a2af1456515d43b6381e38534b069b1c2: [Backport #19242]

	[Bug #19242] Prohibit circular causes to be loaded

	---
	 error.c                     |  4 ++++
	 eval.c                      |  4 ++++
	 eval_error.c                | 11 +++++++++++
	 test/ruby/test_exception.rb | 12 ++++++++++++
	 4 files changed, 31 insertions(+)

1 files changed, 4 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index 0de3105ac7..97484b0b2a 100644
--- a/eval.c
+++ b/eval.c
@@ -528,12 +528,16 @@ exc_setup_message(const rb_execution_context_t *ec, VALUE mesg, VALUE *cause)
     }
 
     if (!nocircular && !NIL_P(*cause) && *cause != Qundef && *cause != mesg) {
+#if 0 /* maybe critical for some cases */
+        rb_exc_check_circular_cause(*cause);
+#else
         VALUE c = *cause;
         while (!NIL_P(c = rb_attr_get(c, id_cause))) {
             if (c == mesg) {
                 rb_raise(rb_eArgError, "circular causes");
             }
         }
+#endif
     }
     return mesg;
 }