From f4da98bf5f5026594c210c77286bad4fb9a64a93 Mon Sep 17 00:00:00 2001
From: Jeremy Evans <code@jeremyevans.net>
Date: Fri, 19 Feb 2016 12:05:27 -0800
Subject: [PATCH] Allow clone to take a second argument passed to
 initialize_clone

---
 object.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/object.c b/object.c
index 2497043..e71e0b1 100644
--- a/object.c
+++ b/object.c
@@ -299,7 +299,7 @@ init_copy(VALUE dest, VALUE obj)
 
 /*
  *  call-seq:
- *     obj.clone -> an_object
+ *     obj.clone(other=nil) -> an_object
  *
  *  Produces a shallow copy of <i>obj</i>---the instance variables of
  *  <i>obj</i> are copied, but not the objects they reference.
@@ -316,13 +316,17 @@ init_copy(VALUE dest, VALUE obj)
  *     s1.inspect          #=> "#<Klass:0x401b3a38 @str=\"Hi\">"
  *     s2.inspect          #=> "#<Klass:0x401b3998 @str=\"Hi\">"
  *
+ *  You can provide another object to this method, which +initialize_clone+
+ *  will be called with in addition to the object's clone, before the object's
+ *  object is frozen.
+ *
  *  This method may have class-specific behavior.  If so, that
  *  behavior will be documented under the #+initialize_copy+ method of
  *  the class.
  */
 
-VALUE
-rb_obj_clone(VALUE obj)
+static VALUE
+rb_obj_clone2(int argc, VALUE *argv, VALUE obj)
 {
     VALUE clone;
     VALUE singleton;
@@ -341,12 +345,23 @@ rb_obj_clone(VALUE obj)
     }
 
     init_copy(clone, obj);
-    rb_funcall(clone, id_init_clone, 1, obj);
+    rb_check_arity(argc, 0, 1);
+    if (argc == 0) {
+      rb_funcall(clone, id_init_clone, 1, obj);
+    } else {
+      rb_funcall(clone, id_init_clone, 2, obj, argv[0]);
+    }
     RBASIC(clone)->flags |= RBASIC(obj)->flags & FL_FREEZE;
 
     return clone;
 }
 
+VALUE
+rb_obj_clone(VALUE obj)
+{
+    return rb_obj_clone2(0, NULL, obj);
+}
+
 /*
  *  call-seq:
  *     obj.dup -> an_object
@@ -3424,7 +3439,7 @@ InitVM_Object(void)
 
     rb_define_method(rb_mKernel, "class", rb_obj_class, 0);
     rb_define_method(rb_mKernel, "singleton_class", rb_obj_singleton_class, 0);
-    rb_define_method(rb_mKernel, "clone", rb_obj_clone, 0);
+    rb_define_method(rb_mKernel, "clone", rb_obj_clone2, -1);
     rb_define_method(rb_mKernel, "dup", rb_obj_dup, 0);
     rb_define_method(rb_mKernel, "itself", rb_obj_itself, 0);
     rb_define_method(rb_mKernel, "initialize_copy", rb_obj_init_copy, 1);
-- 
2.7.0