From 05e0dfa0060aab80afc696161226b2ab0cddfbf9 Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Date: Tue, 17 Feb 2015 09:23:29 +0100
Subject: [PATCH] Reverse iteration in QMetaEnum::valueToKeys().

Otherwise, values that are composed of others are not handled
correctly. For example,
Qt::Dialog|Qt::FramelessWindowHint (Qt::Dialog=0x2|Qt::Window)
is currently output as
"Window|FramelessWindowHint" since
Qt::Window matches first and its bits are removed from the flag value
so that Qt::Dialog in the next iteration no longer matches.

Change-Id: I67db5c977c75f887392aa8f345c5e6e9d82c5c26
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
---
 src/corelib/kernel/qmetaobject.cpp            |  7 ++--
 .../kernel/qmetaenum/tst_qmetaenum.cpp        | 34 +++++++++++++++++++
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index e7be2339da..e89b914227 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -2665,13 +2665,14 @@ QByteArray QMetaEnum::valueToKeys(int value) const
     int count = mobj->d.data[handle + 2];
     int data = mobj->d.data[handle + 3];
     int v = value;
-    for(int i = 0; i < count; i++) {
+    // reverse iterate to ensure values like Qt::Dialog=0x2|Qt::Window are processed first.
+    for (int i = count - 1; i >= 0; --i) {
         int k = mobj->d.data[data + 2*i + 1];
         if ((k != 0 && (v & k) == k ) ||  (k == value))  {
             v = v & ~k;
             if (!keys.isEmpty())
-                keys += '|';
-            keys += stringData(mobj, mobj->d.data[data + 2*i]);
+                keys.prepend('|');
+            keys.prepend(stringData(mobj, mobj->d.data[data + 2*i]));
         }
     }
     return keys;
diff --git a/tests/auto/corelib/kernel/qmetaenum/tst_qmetaenum.cpp b/tests/auto/corelib/kernel/qmetaenum/tst_qmetaenum.cpp
index e81e105bfb..17b00ebf63 100644
--- a/tests/auto/corelib/kernel/qmetaenum/tst_qmetaenum.cpp
+++ b/tests/auto/corelib/kernel/qmetaenum/tst_qmetaenum.cpp
@@ -46,6 +46,8 @@ public:
 
 private slots:
     void fromType();
+    void valuesToKeys_data();
+    void valuesToKeys();
 };
 
 void tst_QMetaEnum::fromType()
@@ -57,5 +59,37 @@ void tst_QMetaEnum::fromType()
     QCOMPARE(meta.keyCount(), 2);
 }
 
+Q_DECLARE_METATYPE(Qt::WindowFlags)
+
+void tst_QMetaEnum::valuesToKeys_data()
+{
+   QTest::addColumn<Qt::WindowFlags>("windowFlags");
+   QTest::addColumn<QByteArray>("expected");
+
+   QTest::newRow("Window")
+       << Qt::WindowFlags(Qt::Window)
+       << QByteArrayLiteral("Window");
+
+   // Verify that Qt::Dialog does not cause 'Window' to appear in the output.
+   QTest::newRow("Frameless_Dialog")
+       << (Qt::Dialog | Qt::FramelessWindowHint)
+       << QByteArrayLiteral("Dialog|FramelessWindowHint");
+
+   // Similarly, Qt::WindowMinMaxButtonsHint should not show up as
+   // WindowMinimizeButtonHint|WindowMaximizeButtonHint
+   QTest::newRow("Tool_MinMax_StaysOnTop")
+       << (Qt::Tool | Qt::WindowMinMaxButtonsHint | Qt::WindowStaysOnTopHint)
+       << QByteArrayLiteral("Tool|WindowMinMaxButtonsHint|WindowStaysOnTopHint");
+}
+
+void tst_QMetaEnum::valuesToKeys()
+{
+    QFETCH(Qt::WindowFlags, windowFlags);
+    QFETCH(QByteArray, expected);
+
+    QMetaEnum me = QMetaEnum::fromType<Qt::WindowFlags>();
+    QCOMPARE(me.valueToKeys(windowFlags), expected);
+}
+
 QTEST_MAIN(tst_QMetaEnum)
 #include "tst_qmetaenum.moc"