array.c: sum for Rational and Float mixed arrays

* array.c (rb_ary_sum): apply the precision compensated algorithm
  for an array in which Rational and Float values are mixed.

* test/ruby/test_array.rb (test_sum): add assertions for the above
  change.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54601 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 28 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 052628352e..6a0f3051eb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Fri Apr 15 22:31:00 2016  Kenta Murata  <mrkn@mrkn.jp>
+
+	* array.c (rb_ary_sum): apply the precision compensated algorithm
+	  for an array in which Rational and Float values are mixed.
+
+	* test/ruby/test_array.rb (test_sum): add assertions for the above
+	  change.
+
 Fri Apr 15 22:30:01 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* thread.c (rb_thread_setname): defer setting native thread name
diff --git a/array.c b/array.c
index d85e32ccae..93d3d47db0 100644
--- a/array.c
+++ b/array.c
@@ -5722,6 +5722,8 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
     if (RB_FLOAT_TYPE_P(e)) {
         /* Kahan's compensated summation algorithm */
         double f, c;
+
+      float_value:
         f = NUM2DBL(v);
         c = 0.0;
         for (; i < RARRAY_LEN(ary); i++) {
@@ -5735,6 +5737,8 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
                 x = FIX2LONG(e);
             else if (RB_TYPE_P(e, T_BIGNUM))
                 x = rb_big2dbl(e);
+            else if (RB_TYPE_P(e, T_RATIONAL))
+                x = rb_num2dbl(e);
             else
                 goto not_float;
 
@@ -5749,6 +5753,20 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
         v = DBL2NUM(f);
     }
 
+    if (RB_TYPE_P(e, T_RATIONAL)) {
+        for (; i < RARRAY_LEN(ary); i++) {
+            e = RARRAY_AREF(ary, i);
+            if (block_given)
+                e = rb_yield(e);
+            if (RB_FLOAT_TYPE_P(e)) {
+                v = rb_to_float(v);
+                goto float_value;
+            }
+            v = rb_funcall(v, idPLUS, 1, e);
+        }
+        return v;
+    }
+
     for (; i < RARRAY_LEN(ary); i++) {
         e = RARRAY_AREF(ary, i);
         if (block_given)
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index ce8a289a6a..929cd1590b 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -2774,6 +2774,8 @@ class TestArray < Test::Unit::TestCase
       small_number /= 10
     end
     assert_float_equal(large_number+(small_number*10), [large_number, *[small_number]*10].sum)
+    assert_float_equal(large_number+(small_number*10), [large_number/1r, *[small_number]*10].sum)
+    assert_float_equal(large_number+(small_number*11), [small_number, large_number/1r, *[small_number]*10].sum)
   end
 
   private