From efbace90a1fae7a5f7ef45360250196125d85f80 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Tue, 9 Nov 2021 15:24:45 -0800
Subject: [PATCH 086/147] QCborValue: fix incorrect to{Array,Map} when the
 value is empty

When QCborValue referred to an empty array or map, toArray() and toMap()
would respectively return the default value instead of the empty object,
as expected.

Pick-to: 6.2 6.3
Change-Id: I5e52dc5b093c43a3b678fffd16b60456d0037ad7
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
(cherry picked from commit de6ced66920600e659dbaa2509526a3bcb0b3360)
---
 src/corelib/serialization/qcborvalue.cpp      |  6 +-
 .../qcborvalue/tst_qcborvalue.cpp             | 87 +++++++++++++++++++
 2 files changed, 91 insertions(+), 2 deletions(-)

diff --git a/src/corelib/serialization/qcborvalue.cpp b/src/corelib/serialization/qcborvalue.cpp
index 89a928d348..3a8c2cb9ec 100644
--- a/src/corelib/serialization/qcborvalue.cpp
+++ b/src/corelib/serialization/qcborvalue.cpp
@@ -2123,7 +2123,8 @@ QCborArray QCborValue::toArray(const QCborArray &defaultValue) const
     Q_ASSERT(n == -1 || container == nullptr);
     if (n < 0)
         dd = container;
-    return dd ? QCborArray(*dd) : defaultValue;
+    // return QCborArray(*dd); but that's UB if dd is nullptr
+    return dd ? QCborArray(*dd) : QCborArray();
 }
 
 /*!
@@ -2165,7 +2166,8 @@ QCborMap QCborValue::toMap(const QCborMap &defaultValue) const
     Q_ASSERT(n == -1 || container == nullptr);
     if (n < 0)
         dd = container;
-    return dd ? QCborMap(*dd) : defaultValue;
+    // return QCborMap(*dd); but that's UB if dd is nullptr
+    return dd ? QCborMap(*dd) : QCborMap();
 }
 
 /*!
diff --git a/tests/auto/corelib/serialization/qcborvalue/tst_qcborvalue.cpp b/tests/auto/corelib/serialization/qcborvalue/tst_qcborvalue.cpp
index 533fb1c8aa..63ce77d67f 100644
--- a/tests/auto/corelib/serialization/qcborvalue/tst_qcborvalue.cpp
+++ b/tests/auto/corelib/serialization/qcborvalue/tst_qcborvalue.cpp
@@ -75,6 +75,7 @@ private slots:
     void arrayStringElements();
     void arraySelfAssign_data() { basics_data(); }
     void arraySelfAssign();
+    void arrayNested();
 
     void mapDefaultInitialization();
     void mapEmptyInitializerList();
@@ -93,6 +94,7 @@ private slots:
     void mapSelfAssign();
     void mapComplexKeys_data() { basics_data(); }
     void mapComplexKeys();
+    void mapNested();
 
     void sorting();
 
@@ -1570,6 +1572,91 @@ void tst_QCborValue::mapComplexKeys()
     QVERIFY(!m.contains(tagged));
 }
 
+void tst_QCborValue::arrayNested()
+{
+    const QCborArray wrongArray = { false, nullptr, QCborValue() };
+    {
+        QCborArray a1 = { 42, 47 };
+        QCborArray a2 = { QCborValue(a1) };
+        QCOMPARE(a2.size(), 1);
+        const QCborValue &first = qAsConst(a2).first();
+        QVERIFY(first.isArray());
+        QCOMPARE(first.toArray(wrongArray).size(), 2);
+        QCOMPARE(first.toArray(wrongArray).first(), 42);
+        QCOMPARE(first.toArray(wrongArray).last(), 47);
+    }
+    {
+        QCborArray a1 = { 42, 47 };
+        QCborArray a2 = { QCborValue(a1) };
+        QCOMPARE(a2.size(), 1);
+        QCborValueRef first = a2.first();
+        QVERIFY(first.isArray());
+        QCOMPARE(first.toArray(wrongArray).size(), 2);
+        QCOMPARE(first.toArray(wrongArray).first(), 42);
+        QCOMPARE(first.toArray(wrongArray).last(), 47);
+    }
+
+    {
+        QCborArray a1;
+        a1 = { QCborValue(a1) };        // insert it into itself
+        QCOMPARE(a1.size(), 1);
+        const QCborValue &first = qAsConst(a1).first();
+        QVERIFY(first.isArray());
+        QCOMPARE(first, QCborArray());
+        QCOMPARE(first.toArray(wrongArray), QCborArray());
+    }
+    {
+        QCborArray a1;
+        a1 = { QCborValue(a1) };        // insert it into itself
+        QCborValueRef first = a1.first();
+        QVERIFY(first.isArray());
+        QCOMPARE(first, QCborArray());
+        QCOMPARE(first.toArray(wrongArray), QCborArray());
+    }
+    {
+        QCborArray a1;
+        a1.append(a1);                  // insert into itself
+        QCOMPARE(a1.size(), 1);
+        const QCborValue &first = qAsConst(a1).first();
+        QVERIFY(first.isArray());
+        QCOMPARE(first, QCborArray());
+        QCOMPARE(first.toArray(), QCborArray());
+    }
+    {
+        QCborArray a1;
+        a1.append(a1);                  // insert into itself
+        QCborValueRef first = a1.first();
+        QVERIFY(first.isArray());
+        QCOMPARE(first, QCborArray());
+        QCOMPARE(first.toArray(), QCborArray());
+    }
+}
+
+void tst_QCborValue::mapNested()
+{
+    const QCborMap wrongMap = { { -1, false }, {-2, nullptr }, { -3, QCborValue() } };
+    {
+        QCborMap m1 = { {1, 42}, {2, 47} };
+        QCborMap m2 = { { QString(), m1 } };
+        QCOMPARE(m2.size(), 1);
+        const QCborValue &first = m2.constBegin().value();
+        QVERIFY(first.isMap());
+        QCOMPARE(first.toMap(wrongMap).size(), 2);
+        QCOMPARE(first.toMap(wrongMap).begin().key(), 1);
+        QCOMPARE(first.toMap(wrongMap).begin().value(), 42);
+    }
+
+    {
+        QCborMap m1;
+        m1 = { { QString(), QCborValue(m1) } };         // insert it into itself
+        QCOMPARE(m1.size(), 1);
+        const QCborValue &first = m1.constBegin().value();
+        QVERIFY(first.isMap());
+        QCOMPARE(first, QCborMap());
+        QCOMPARE(first.toMap(wrongMap), QCborMap());
+    }
+}
+
 void tst_QCborValue::sorting()
 {
     QCborValue vundef, vnull(nullptr);
-- 
2.40.1