Round to nearest millisecond in QDateTime::fromCFDate()

CFAbsoluteTime is measured in seconds, represented by a double,
so when converting milliseconds to CFAbsoluteTime we may get a
slight error due to missing precision in double to represent
the milliseconds exactly. By rounding to the closest millisecond
when converting back, we avoid truncating and being one ms off.

Change-Id: If1e99f97b000fb8cb893ddfc5d7ba81096c0ea88
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/corelib/kernel/qcore_foundation.mm b/src/corelib/kernel/qcore_foundation.mm
index 2291017a5d..f5ccd1c1f2 100644
--- a/src/corelib/kernel/qcore_foundation.mm
+++ b/src/corelib/kernel/qcore_foundation.mm
@@ -375,8 +375,8 @@ QDateTime QDateTime::fromCFDate(CFDateRef date)
 {
     if (!date)
         return QDateTime();
-    return QDateTime::fromMSecsSinceEpoch(static_cast<qint64>((CFDateGetAbsoluteTime(date)
-                                                    + kCFAbsoluteTimeIntervalSince1970) * 1000));
+    CFAbsoluteTime sSinceEpoch = kCFAbsoluteTimeIntervalSince1970 + CFDateGetAbsoluteTime(date);
+    return QDateTime::fromMSecsSinceEpoch(qRound64(sSinceEpoch * 1000));
 }
 
 /*!
@@ -404,7 +404,7 @@ QDateTime QDateTime::fromNSDate(const NSDate *date)
 {
     if (!date)
         return QDateTime();
-    return QDateTime::fromMSecsSinceEpoch(static_cast<qint64>([date timeIntervalSince1970] * 1000));
+    return QDateTime::fromMSecsSinceEpoch(qRound64([date timeIntervalSince1970] * 1000));
 }
 
 /*!