merge revision(s) 55604,55612: [Backport #13138]

	* numeric.c (flo_round): [EXPERIMENTAL] adjust the case that the
	  receiver is close to the exact but unrepresentable middle value
	  of two values in the given precision.
	  http://d.hatena.ne.jp/hnw/20160702

	numeric.c: round as double

	* numeric.c (flo_round): compare as double, not long double with
	  i387.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@58513 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

4 files changed, 24 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 3e0ef09f87..c7edabb5ad 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Sun Apr 30 22:24:25 2017  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* numeric.c (flo_round): [EXPERIMENTAL] adjust the case that the
+	  receiver is close to the exact but unrepresentable middle value
+	  of two values in the given precision.
+	  http://d.hatena.ne.jp/hnw/20160702
+
 Sun Apr  9 22:21:23 2017  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	thread.c: rb_thread_fd_close [ci skip]
diff --git a/numeric.c b/numeric.c
index ca961d8d6c..c1c673927c 100644
--- a/numeric.c
+++ b/numeric.c
@@ -1786,7 +1786,7 @@ static VALUE
 flo_round(int argc, VALUE *argv, VALUE num)
 {
     VALUE nd;
-    double number, f;
+    double number, f, x;
     int ndigits = 0;
     int binexp;
     enum {float_dig = DBL_DIG+2};
@@ -1828,8 +1828,14 @@ flo_round(int argc, VALUE *argv, VALUE num)
 	return DBL2NUM(0);
     }
     f = pow(10, ndigits);
-    return DBL2NUM(round(number * f) / f);
-}
+    x = round(number * f);
+    if (x > 0) {
+	if ((double)((x + 0.5) / f) <= number) x += 1;
+    }
+    else {
+	if ((double)((x - 0.5) / f) >= number) x -= 1;
+    }
+    return DBL2NUM(x / f);}
 
 /*
  *  call-seq:
diff --git a/test/ruby/test_float.rb b/test/ruby/test_float.rb
index 3afd26d0b4..7d979a824f 100644
--- a/test/ruby/test_float.rb
+++ b/test/ruby/test_float.rb
@@ -442,6 +442,11 @@ class TestFloat < Test::Unit::TestCase
     assert_raise(TypeError) {1.0.round(nil)}
     def (prec = Object.new).to_int; 2; end
     assert_equal(1.0, 0.998.round(prec))
+
+    assert_equal(+5.02, +5.015.round(2))
+    assert_equal(-5.02, -5.015.round(2))
+    assert_equal(+1.26, +1.255.round(2))
+    assert_equal(-1.26, -1.255.round(2))
   end
 
   VS = [
diff --git a/version.h b/version.h
index 4006cceb33..cab6d40e47 100644
--- a/version.h
+++ b/version.h
@@ -1,10 +1,10 @@
 #define RUBY_VERSION "2.3.5"
-#define RUBY_RELEASE_DATE "2017-04-09"
-#define RUBY_PATCHLEVEL 303
+#define RUBY_RELEASE_DATE "2017-04-30"
+#define RUBY_PATCHLEVEL 304
 
 #define RUBY_RELEASE_YEAR 2017
 #define RUBY_RELEASE_MONTH 4
-#define RUBY_RELEASE_DAY 9
+#define RUBY_RELEASE_DAY 30
 
 #include "ruby/version.h"