Don't truncate QDateTime milliseconds when storing QSettings on Apple platforms

The fix is trivial, but the patch adds a new QSettings tests that iterates most
of the QMetaTypes and verifies that storing and retrieving them again gives the
same value. This is a more complete test than the testVariantTypes tests, which
is limited to a subset of the QVariant types. The new tests borrows logic from
the QMetaType test machinery.

QSettings has been Q_ENUM'ified in the process, for improved debug output.

Note that on backends such as the INI backend, the metatype of the QVariant read
from the settings will be a string, so it won't match the input QVariant type,
but the result of converting that to the original value type should still work.

Task-number: QTBUG-56124
Change-Id: Ib03a26abf77c9fb449b94160d28bc4baeb095f25
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

2 files changed, 15 insertions, 13 deletions

diff --git a/src/corelib/io/qsettings.h b/src/corelib/io/qsettings.h
index 21fb9519de..edd59026ed 100644
--- a/src/corelib/io/qsettings.h
+++ b/src/corelib/io/qsettings.h
@@ -80,6 +80,9 @@ public:
         AccessError,
         FormatError
     };
+#ifndef QT_NO_QOBJECT
+    Q_ENUM(Status)
+#endif
 
     enum Format {
         NativeFormat,
@@ -108,11 +111,17 @@ public:
         CustomFormat15,
         CustomFormat16
     };
+#ifndef QT_NO_QOBJECT
+    Q_ENUM(Format)
+#endif
 
     enum Scope {
         UserScope,
         SystemScope
     };
+#ifndef QT_NO_QOBJECT
+    Q_ENUM(Scope)
+#endif
 
 #ifndef QT_NO_QOBJECT
     explicit QSettings(const QString &organization,
diff --git a/src/corelib/io/qsettings_mac.cpp b/src/corelib/io/qsettings_mac.cpp
index 77f185d735..7d4f527ac5 100644
--- a/src/corelib/io/qsettings_mac.cpp
+++ b/src/corelib/io/qsettings_mac.cpp
@@ -175,17 +175,12 @@ static QCFType<CFPropertyListRef> macValue(const QVariant &value)
         break;
     case QVariant::DateTime:
         {
-            /*
-                CFDate, unlike QDateTime, doesn't store timezone information.
-            */
-            QDateTime dt = value.toDateTime();
-            if (dt.timeSpec() == Qt::LocalTime) {
-                QDateTime reference;
-                reference.setSecsSinceEpoch(qint64(kCFAbsoluteTimeIntervalSince1970));
-                result = CFDateCreate(kCFAllocatorDefault, CFAbsoluteTime(reference.secsTo(dt)));
-            } else {
+            QDateTime dateTime = value.toDateTime();
+            // CFDate, unlike QDateTime, doesn't store timezone information
+            if (dateTime.timeSpec() == Qt::LocalTime)
+                result = dateTime.toCFDate();
+            else
                 goto string_case;
-            }
         }
         break;
     case QVariant::Bool:
@@ -303,9 +298,7 @@ static QVariant qtValue(CFPropertyListRef cfvalue)
         }
         return map;
     } else if (typeId == CFDateGetTypeID()) {
-        QDateTime dt;
-        dt.setSecsSinceEpoch(qint64(kCFAbsoluteTimeIntervalSince1970));
-        return dt.addSecs((int)CFDateGetAbsoluteTime(static_cast<CFDateRef>(cfvalue)));
+        return QDateTime::fromCFDate(static_cast<CFDateRef>(cfvalue));
     }
     return QVariant();
 }