From f7847ccd22c710e15e0dcd10e99b60f9a9262081 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Tue, 14 May 2024 07:23:38 +0200
Subject: [PATCH] QDir: replace a QScopedArrayPointer with a QVLA

QDirSortItem contains three implicitly-shared members (two QStrings
and one QFileInfo), so the mere default-initialization of the
QDirSortItem[n] array with which we initialize the QScopedArrayPointer
will take quite some time.

Using QVarLengthArray, OTOH, delays construction until we have the
data to initialize the sort items, saving n default constructor and n
move assignment operator calls, plus the memory allocation for the
case where we have less than 65 elements to sort.

This code precedes the start of the public history, but the
emplacement won't work before 905bc6293354a0d3ee832b6dd3f632a647f809f3
introduced the QDirSortItem ctor, so not picking back further than
that.

Change-Id: I262217eabaded2a6aef08b87fc6369812bc8958a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 81a0753299fb8cc3e6b4b5e41a0292024ccea9e5)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/io/qdir.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/corelib/io/qdir.cpp b/src/corelib/io/qdir.cpp
index 3ad804b9e88..482e6d14fee 100644
--- a/src/corelib/io/qdir.cpp
+++ b/src/corelib/io/qdir.cpp
@@ -313,9 +313,10 @@ inline void QDirPrivate::sortFileList(QDir::SortFlags sort, const QFileInfoList
                 names->append(fi.fileName());
         }
     } else {
-        QScopedArrayPointer<QDirSortItem> si(new QDirSortItem[n]);
+        QVarLengthArray<QDirSortItem, 64> si;
+        si.reserve(n);
         for (qsizetype i = 0; i < n; ++i)
-            si[i] = QDirSortItem{l.at(i), sort};
+            si.emplace_back(l.at(i), sort);
 
 #ifndef QT_BOOTSTRAPPED
     if (sort.testAnyFlag(QDir::LocaleAware)) {