* time.c (rb_time_unmagnify_to_float): Avoid double rounding.

Reported by Tsuyoshi Sawada.
  https://bugs.ruby-lang.org/issues/10135#note-1



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47289 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Tue Aug 26 20:46:55 2014  Tanaka Akira  <akr@fsij.org>
+
+	* time.c (rb_time_unmagnify_to_float): Avoid double rounding.
+	  Reported by Tsuyoshi Sawada.
+	  https://bugs.ruby-lang.org/issues/10135#note-1
+
 Tue Aug 26 17:12:47 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* io.c (io_close): ignore only "closed stream" IOError and

test/ruby/test_time.rb

@@ -423,6 +423,12 @@ class TestTime < Test::Unit::TestCase
     assert_equal(946684800.0, t2000.to_f)
   end
 
+  def test_to_f_accuracy
+    # https://bugs.ruby-lang.org/issues/10135#note-1
+    f = 1381089302.195
+    assert_equal(f, Time.at(f).to_f, "[ruby-core:64373] [Bug #10135] note-1")
+  end
+
   def test_cmp
     t2000 = get_t2000
     assert_equal(-1, t2000 <=> Time.gm(2001))

time.c

@@ -697,7 +697,10 @@ rb_time_unmagnify_to_float(wideval_t w)
     }
 #endif
     v = w2v(w);
-    return quo(v, DBL2NUM(TIME_SCALE));
+    if (RB_TYPE_P(v, T_RATIONAL))
+        return rb_Float(quo(v, INT2FIX(TIME_SCALE)));
+    else
+        return quo(v, DBL2NUM(TIME_SCALE));
 }
 
 static void