nobu	2016-11-04 16:31:47 +0900 (Fri, 04 Nov 2016)

  New Revision: 56557

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=56557

  Log:
    util.c: round to even
    
    * util.c (ruby_dtoa): round to even, instead of rounding to
      nearest.  [ruby-core:77864] [Bug #12889]

  Modified files:
    trunk/ChangeLog
    trunk/test/ruby/test_sprintf.rb
    trunk/util.c
Index: util.c
===================================================================
--- util.c	(revision 56556)
+++ util.c	(revision 56557)
@@ -3165,7 +3165,7 @@ ruby_dtoa(double d_, int mode, int ndigi https://github.com/ruby/ruby/blob/trunk/util.c#L3165
 
     int bbits, b2, b5, be, dig, i, ieps, ilim, ilim0, ilim1,
         j, j1, k, k0, k_check, leftright, m2, m5, s2, s5,
-        spec_case, try_quick;
+        spec_case, try_quick, half = 0;
     Long L;
 #ifndef Sudden_Underflow
     int denorm;
@@ -3452,17 +3452,17 @@ ruby_dtoa(double d_, int mode, int ndigi https://github.com/ruby/ruby/blob/trunk/util.c#L3452
                     ilim = i;
                 *s++ = '0' + (int)L;
                 if (i == ilim) {
-                    double x;
                     if (dval(d) > 0.5 + dval(eps))
                         goto bump_up;
-                    else if (!isinf(x = d_ * tens[ilim-1] + 0.5) &&
-                             dval(d) > modf(x, &x))
-                        goto bump_up;
                     else if (dval(d) < 0.5 - dval(eps)) {
                         while (*--s == '0') ;
                         s++;
                         goto ret1;
                     }
+                    half = 1;
+                    if ((*(s-1) - '0') & 1) {
+                        goto bump_up;
+                    }
                     break;
                 }
             }
@@ -3770,12 +3770,13 @@ keep_dig: https://github.com/ruby/ruby/blob/trunk/util.c#L3770
                 *s++ = '1';
                 goto ret;
             }
-        ++*s++;
+        if (!half || (*s - '0') & 1)
+            ++*s;
     }
     else {
         while (*--s == '0') ;
-        s++;
     }
+    s++;
 ret:
     Bfree(S);
     if (mhi) {
Index: test/ruby/test_sprintf.rb
===================================================================
--- test/ruby/test_sprintf.rb	(revision 56556)
+++ test/ruby/test_sprintf.rb	(revision 56557)
@@ -283,7 +283,16 @@ class TestSprintf < Test::Unit::TestCase https://github.com/ruby/ruby/blob/trunk/test/ruby/test_sprintf.rb#L283
   end
 
   def test_float_prec
-    assert_equal("5.03", sprintf("%.2f",5.025))
+    assert_equal("5.00", sprintf("%.2f",5.005))
+    assert_equal("5.02", sprintf("%.2f",5.015))
+    assert_equal("5.02", sprintf("%.2f",5.025))
+    assert_equal("5.04", sprintf("%.2f",5.035))
+    bug12889 = '[ruby-core:77864] [Bug #12889]'
+    assert_equal("1234567892", sprintf("%.0f", 1234567891.99999))
+    assert_equal("1234567892", sprintf("%.0f", 1234567892.49999))
+    assert_equal("1234567892", sprintf("%.0f", 1234567892.50000))
+    assert_equal("1234567894", sprintf("%.0f", 1234567893.50000))
+    assert_equal("1234567892", sprintf("%.0f", 1234567892.00000), bug12889)
   end
 
   BSIZ = 120
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 56556)
+++ ChangeLog	(revision 56557)
@@ -1,3 +1,8 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Fri Nov  4 16:31:45 2016  Nobuyoshi Nakada  <nobu@r...>
+
+	* util.c (ruby_dtoa): round to even, instead of rounding to
+	  nearest.  [ruby-core:77864] [Bug #12889]
+
 Fri Nov  4 15:31:00 2016  NARUSE, Yui  <naruse@r...>
 
 	* configure.in: Add compiler version message into rbconfig

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