From 16db1d21659793909bd1719805d7ff8de6906f88 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Mon, 12 Jul 2021 08:17:07 +0200
Subject: [PATCH] QDuplicateTracker: reserve() for at least Prealloc elements
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We have space for so many elements, so reserve()ing anything less
makes no sense.

Pick-to: 6.2 6.1 5.15
Change-Id: I84d692b10a6a491c37661f84aa3fdd9af43d71e5
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
---
 src/corelib/tools/qduplicatetracker_p.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/corelib/tools/qduplicatetracker_p.h b/src/corelib/tools/qduplicatetracker_p.h
index 47c97100f9..5cfa19e03b 100644
--- a/src/corelib/tools/qduplicatetracker_p.h
+++ b/src/corelib/tools/qduplicatetracker_p.h
@@ -81,9 +81,10 @@ class QDuplicateTracker {
 
     char buffer[bufferSize(Prealloc)];
     std::pmr::monotonic_buffer_resource res{buffer, sizeof buffer};
-    std::pmr::unordered_set<T, QHasher<T>> set{&res};
+    std::pmr::unordered_set<T, QHasher<T>> set{Prealloc, &res};
 #else
-    QSet<T> set;
+    static QSet<T> makeQSet() { QSet<T> r; r.reserve(Prealloc); return r; }
+    QSet<T> set = makeQSet();
     int setSize = 0;
 #endif
     Q_DISABLE_COPY_MOVE(QDuplicateTracker);