merge revision(s) 58796: [Backport #13545]

	Merge latest dtoa.c [Bug #13545]

	Apply some part of http://www.netlib.org/fp/dtoa.c with my eyes...

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@59298 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 7 insertions, 5 deletions

diff --git a/util.c b/util.c
index 4ae7c4fc96..0934996984 100644
--- a/util.c
+++ b/util.c
@@ -2109,7 +2109,7 @@ break2:
     for (nd = nf = 0; (c = *s) >= '0' && c <= '9'; nd++, s++)
         if (nd < 9)
             y = 10*y + c - '0';
-        else if (nd < 16)
+        else if (nd < DBL_DIG + 2)
             z = 10*z + c - '0';
     nd0 = nd;
 #ifdef USE_LOCALE
@@ -2149,17 +2149,19 @@ break2:
         for (; c >= '0' && c <= '9'; c = *++s) {
 have_dig:
             nz++;
-            if (nd > DBL_DIG * 4) continue;
+            if (nd > DBL_DIG * 4) {
+		continue;
+	    }
             if (c -= '0') {
                 nf += nz;
                 for (i = 1; i < nz; i++)
                     if (nd++ < 9)
                         y *= 10;
-                    else if (nd <= DBL_DIG + 1)
+                    else if (nd <= DBL_DIG + 2)
                         z *= 10;
                 if (nd++ < 9)
                     y = 10*y + c;
-                else if (nd <= DBL_DIG + 1)
+                else if (nd <= DBL_DIG + 2)
                     z = 10*z + c;
                 nz = 0;
             }
@@ -2247,7 +2249,7 @@ ret0:
 
     if (!nd0)
         nd0 = nd;
-    k = nd < DBL_DIG + 1 ? nd : DBL_DIG + 1;
+    k = nd < DBL_DIG + 2 ? nd : DBL_DIG + 2;
     dval(rv) = y;
     if (k > 9) {
 #ifdef SET_INEXACT