Fix issue with Array#rindex when rb_equal modifies receiver array

Fixes [Bug #15951]

Closes: https://github.com/ruby/ruby/pull/2250

1 files changed, 3 insertions, 0 deletions

diff --git a/array.c b/array.c
index de2f80828a..8501074ebe 100644
--- a/array.c
+++ b/array.c
@@ -1805,6 +1805,9 @@ rb_ary_rindex(int argc, VALUE *argv, VALUE ary)
 	if (rb_equal(e, val)) {
 	    return LONG2NUM(i);
 	}
+        if (i > RARRAY_LEN(ary)) {
+            break;
+        }
     }
     return Qnil;
 }