commit fa0279d947c3962c3f8c32852278d3ebb964cb19
Author: Koichi Sasada <ko1@atdot.net>
Date:   Wed Jul 28 13:40:30 2021 +0900

    should not share same `def` for specialized method
    
    Because the key of redefine table is `def`, `def` should be
    unique for each optimized method (`alias` is not allowed).

diff --git a/array.c b/array.c
index 3cb57a0872..36f712bcac 100644
--- a/array.c
+++ b/array.c
@@ -8384,7 +8384,7 @@ Init_Array(void)
     rb_define_method(rb_cArray, "each_index", rb_ary_each_index, 0);
     rb_define_method(rb_cArray, "reverse_each", rb_ary_reverse_each, 0);
     rb_define_method(rb_cArray, "length", rb_ary_length, 0);
-    rb_define_alias(rb_cArray,  "size", "length");
+    rb_define_method(rb_cArray, "size", rb_ary_length, 0);
     rb_define_method(rb_cArray, "empty?", rb_ary_empty_p, 0);
     rb_define_method(rb_cArray, "find_index", rb_ary_index, -1);
     rb_define_method(rb_cArray, "index", rb_ary_index, -1);