Stop using QVector in QFileInfoPrivate

This was added in 32629676b977d98e853fc6101a63c0d888ff5598 for Qt 5.1
because QDateTime always allocated memory, so QVector was much faster
for default-created objects. Since Qt 5.7, QDateTime no longer allocates
memory in the default constructor, and in Qt 5.8 on 64-bit systems, it
won't allocate memory at all for most reasonable dates, so construction
times are acceptable now.

Change-Id: If0ad4d988da143b3b1b2fffd1480e83121cddc8c
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

2 files changed, 14 insertions, 15 deletions

diff --git a/src/corelib/io/qfileinfo.cpp b/src/corelib/io/qfileinfo.cpp
index f7358d61b3..d301b10004 100644
--- a/src/corelib/io/qfileinfo.cpp
+++ b/src/corelib/io/qfileinfo.cpp
@@ -186,17 +186,22 @@ uint QFileInfoPrivate::getFileFlags(QAbstractFileEngine::FileFlags request) cons
 QDateTime &QFileInfoPrivate::getFileTime(QAbstractFileEngine::FileTime request) const
 {
     Q_ASSERT(fileEngine); // should never be called when using the native FS
-    if (fileTimes.size() != 3)
-        fileTimes.resize(3);
     if (!cache_enabled)
         clearFlags();
-    uint cf;
-    if (request == QAbstractFileEngine::CreationTime)
+
+    uint cf = 0;
+    switch (request) {
+    case QAbstractFileEngine::AccessTime:
+        cf = CachedATime;
+        break;
+    case QAbstractFileEngine::CreationTime:
         cf = CachedCTime;
-    else if (request == QAbstractFileEngine::ModificationTime)
+        break;
+    case QAbstractFileEngine::ModificationTime:
         cf = CachedMTime;
-    else
-        cf = CachedATime;
+        break;
+    }
+
     if (!getCachedFlag(cf)) {
         fileTimes[request] = fileEngine->fileTime(request);
         setCachedFlag(cf);
diff --git a/src/corelib/io/qfileinfo_p.h b/src/corelib/io/qfileinfo_p.h
index 806df179e8..d45cf6be33 100644
--- a/src/corelib/io/qfileinfo_p.h
+++ b/src/corelib/io/qfileinfo_p.h
@@ -56,7 +56,6 @@
 #include "qatomic.h"
 #include "qshareddata.h"
 #include "qfilesystemengine_p.h"
-#include "qvector.h"
 
 #include <QtCore/private/qabstractfileengine_p.h>
 #include <QtCore/private/qfilesystementry_p.h>
@@ -158,19 +157,14 @@ public:
     QScopedPointer<QAbstractFileEngine> const fileEngine;
 
     mutable QString fileNames[QAbstractFileEngine::NFileNames];
-    mutable QString fileOwners[2];
+    mutable QString fileOwners[2];  // QAbstractFileEngine::FileOwner: OwnerUser and OwnerGroup
+    mutable QDateTime fileTimes[4]; // QAbstractFileEngine::FileTime: BirthTime, MetadataChangeTime, ModificationTime, AccessTime
 
     mutable uint cachedFlags : 30;
     bool const isDefaultConstructed : 1; // QFileInfo is a default constructed instance
     bool cache_enabled : 1;
     mutable uint fileFlags;
     mutable qint64 fileSize;
-    // ### Qt6: FIXME: This vector is essentially a plain array
-    // mutable QDateTime fileTimes[3], but the array is slower
-    // to initialize than the QVector as QDateTime has a pimpl.
-    // In Qt 6, QDateTime should inline its data members,
-    // and this here can be an array again.
-    mutable QVector<QDateTime> fileTimes;
     inline bool getCachedFlag(uint c) const
     { return cache_enabled ? (cachedFlags & c) : 0; }
     inline void setCachedFlag(uint c) const