QFileInfo: make stat method public

Forcing the reading of all file system attributes is generally useful in
multi-threaded applications, and has at least one more use case in Qt.

Using it in QFileSystemWatcher on Windows avoids several file system
accesses.

Task-number: QTBUG-41373
Change-Id: Ib3c3243fd083142393ad46d62f49cb4f7bfda17c
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/corelib/io/qfileinfo.cpp

@@ -308,6 +308,8 @@ QDateTime &QFileInfoPrivate::getFileTime(QAbstractFileEngine::FileTime request)
     refreshes the file information: refresh(). If you want to switch
     off a QFileInfo's caching and force it to access the file system
     every time you request information from it call setCaching(false).
+    If you want to make sure that all information is read from the
+    file system, use stat().
 
     \sa QDir, QFile
 */
@@ -1509,8 +1511,6 @@ void QFileInfo::setCaching(bool enable)
 }
 
 /*!
-    \internal
-
     Reads all attributes from the file system.
 
     This is useful when information about the file system is collected in a

src/corelib/io/qfileinfo.h

@@ -175,13 +175,12 @@ public:
 
     bool caching() const;
     void setCaching(bool on);
+    void stat();
 
 protected:
     QSharedDataPointer<QFileInfoPrivate> d_ptr;
 
 private:
-    friend class QFileInfoGatherer;
-    void stat();
     QFileInfoPrivate* d_func();
     inline const QFileInfoPrivate* d_func() const
     {

src/corelib/io/qfilesystemwatcher_win.cpp

@@ -372,6 +372,7 @@ QStringList QWindowsFileSystemWatcherEngine::addPaths(const QStringList &paths,
             normalPath.chop(1);
         }
         QFileInfo fileInfo(normalPath);
+        fileInfo.stat();
         if (!fileInfo.exists())
             continue;