From b59a158a1870000ef1db5acd52afa1b40e2c4fe6 Mon Sep 17 00:00:00 2001
From: akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Fri, 15 Apr 2016 16:26:38 +0000
Subject: [PATCH] * array.c (rb_ary_sum): Don't yield same element twice.  
 Found by nagachika.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54609 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog               | 5 +++++
 array.c                 | 4 ++++
 test/ruby/test_array.rb | 7 +++++++
 3 files changed, 16 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index cd6fdcd76e..5ac0e5db09 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Apr 16 01:16:02 2016  Tanaka Akira  <akr@fsij.org>
+
+	* array.c (rb_ary_sum): Don't yield same element twice.
+	  Found by nagachika.
+
 Sat Apr 16 01:03:32 2016  Tanaka Akira  <akr@fsij.org>
 
 	* array.c (rb_ary_sum): Fix SEGV by [1/2r, 1].sum.
diff --git a/array.c b/array.c
index 5fe5800954..f0a212de08 100644
--- a/array.c
+++ b/array.c
@@ -5736,12 +5736,14 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
 
         f = NUM2DBL(v);
         c = 0.0;
+        goto has_float_value;
         for (; i < RARRAY_LEN(ary); i++) {
             double x, y, t;
             e = RARRAY_AREF(ary, i);
             if (block_given)
                 e = rb_yield(e);
             if (RB_FLOAT_TYPE_P(e))
+              has_float_value:
                 x = RFLOAT_VALUE(e);
             else if (FIXNUM_P(e))
                 x = FIX2LONG(e);
@@ -5763,10 +5765,12 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
         v = DBL2NUM(f);
     }
 
+    goto has_some_value;
     for (; i < RARRAY_LEN(ary); i++) {
         e = RARRAY_AREF(ary, i);
         if (block_given)
             e = rb_yield(e);
+      has_some_value:
         v = rb_funcall(v, idPLUS, 1, e);
     }
     return v;
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index fb6b2a42ad..4ae5f9f820 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -1,6 +1,7 @@
 # coding: US-ASCII
 # frozen_string_literal: false
 require 'test/unit'
+require "delegate"
 require "rbconfig/sizeof"
 
 class TestArray < Test::Unit::TestCase
@@ -2769,6 +2770,12 @@ class TestArray < Test::Unit::TestCase
     assert_int_equal(13, [1, 2].sum(10))
     assert_int_equal(16, [1, 2].sum(10) {|v| v * 2 })
 
+    yielded = []
+    three = SimpleDelegator.new(3)
+    ary = [1, 2.0, three]
+    assert_float_equal(12.0, ary.sum {|x| yielded << x; x * 2 })
+    assert_equal(ary, yielded)
+
     assert_raise(TypeError) { [Object.new].sum }
 
     large_number = 100000000