QDuplicateTracker: add clear()

I'll need it in QFactoryLoader.

Pick-to: 6.2
Change-Id: Ice04365c72984d07a64dfffd16b47f68d25252b4
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

2 files changed, 21 insertions, 0 deletions

diff --git a/src/corelib/tools/qduplicatetracker_p.h b/src/corelib/tools/qduplicatetracker_p.h
index 19f69161a6..eab63bab9b 100644
--- a/src/corelib/tools/qduplicatetracker_p.h
+++ b/src/corelib/tools/qduplicatetracker_p.h
@@ -148,6 +148,11 @@ public:
             return appendTo(c); // lvalue version
         }
     }
+
+    void clear()
+    {
+        set.clear();
+    }
 };
 
 QT_END_NAMESPACE
diff --git a/tests/auto/corelib/tools/qduplicatetracker/tst_qduplicatetracker.cpp b/tests/auto/corelib/tools/qduplicatetracker/tst_qduplicatetracker.cpp
index 12a4103060..f2cb3b3b44 100644
--- a/tests/auto/corelib/tools/qduplicatetracker/tst_qduplicatetracker.cpp
+++ b/tests/auto/corelib/tools/qduplicatetracker/tst_qduplicatetracker.cpp
@@ -38,6 +38,7 @@ class tst_QDuplicateTracker : public QObject
     Q_OBJECT
 private slots:
     void hasSeen();
+    void clear();
     void appendTo();
     void appendTo_special();
 };
@@ -76,6 +77,21 @@ void tst_QDuplicateTracker::hasSeen()
     }
 }
 
+void tst_QDuplicateTracker::clear()
+{
+    QDuplicateTracker<int, 2> tracker;
+    QVERIFY(!tracker.hasSeen(0));
+    QVERIFY(tracker.hasSeen(0));
+    QVERIFY(!tracker.hasSeen(1));
+    QVERIFY(tracker.hasSeen(1));
+
+    tracker.clear();
+    QVERIFY(!tracker.hasSeen(0));
+    QVERIFY(tracker.hasSeen(0));
+    QVERIFY(!tracker.hasSeen(1));
+    QVERIFY(tracker.hasSeen(1));
+}
+
 void tst_QDuplicateTracker::appendTo()
 {
     QDuplicateTracker<int, 2> tracker;