Docs: Separate documentation for UnboundMethod#==

proc.c

@@ -1840,6 +1840,22 @@ method_eq(VALUE method, VALUE other)
     return Qtrue;
 }
 
+/*
+ * call-seq:
+ *   meth.eql?(other_meth)  -> true or false
+ *   meth == other_meth  -> true or false
+ *
+ * Two unbound method objects are equal if they refer to the same
+ * method definition.
+ *
+ *    Array.instance_method(:each_slice) == Enumerable.instance_method(:each_slice)
+ *    #=> true
+ *
+ *    Array.instance_method(:sum) == Enumerable.instance_method(:sum)
+ *    #=> false, Array redefines the method for efficiency
+ */
+#define unbound_method_eq method_eq
+
 /*
  * call-seq:
  *    meth.hash   -> integer
@@ -4334,8 +4350,8 @@ Init_Proc(void)
     rb_cUnboundMethod = rb_define_class("UnboundMethod", rb_cObject);
     rb_undef_alloc_func(rb_cUnboundMethod);
     rb_undef_method(CLASS_OF(rb_cUnboundMethod), "new");
-    rb_define_method(rb_cUnboundMethod, "==", method_eq, 1);
-    rb_define_method(rb_cUnboundMethod, "eql?", method_eq, 1);
+    rb_define_method(rb_cUnboundMethod, "==", unbound_method_eq, 1);
+    rb_define_method(rb_cUnboundMethod, "eql?", unbound_method_eq, 1);
     rb_define_method(rb_cUnboundMethod, "hash", method_hash, 0);
     rb_define_method(rb_cUnboundMethod, "clone", method_clone, 0);
     rb_define_method(rb_cUnboundMethod, "arity", method_arity_m, 0);