Get rid of shared null for QByteArray, QString and QVector

As a side effect, data() can now return a nullptr. This
has the potential to cause crashes in existig code. To work
around this, return an empty string from QString::data()
and QByteArray::data() for now.

For Qt 6 (and once all our internal issues are fixed), data()
will by default return a nullptr for a null QString, but we'll
offer a #define to enable backwards compatible behavior.

Change-Id: I4f66d97ff1dce3eb99a239f1eab9106fa9b1741a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

6 files changed, 75 insertions, 38 deletions

diff --git a/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp b/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
index 73d9f8e765..940865b98e 100644
--- a/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
+++ b/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
@@ -2277,7 +2277,7 @@ void tst_QByteArray::literals()
     QVERIFY(str.length() == 4);
     QCOMPARE(str.capacity(), 0);
     QVERIFY(str == "abcd");
-    QVERIFY(str.data_ptr()->isStatic());
+    QVERIFY(!str.data_ptr()->isMutable());
 
     const char *s = str.constData();
     QByteArray str2 = str;
diff --git a/tests/auto/corelib/text/qstring/tst_qstring.cpp b/tests/auto/corelib/text/qstring/tst_qstring.cpp
index 81a08eb59e..4d2e91a694 100644
--- a/tests/auto/corelib/text/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/text/qstring/tst_qstring.cpp
@@ -4014,7 +4014,7 @@ void tst_QString::fromRawData()
 {
     const QChar ptr[] = { 0x1234, 0x0000 };
     QString cstr = QString::fromRawData(ptr, 1);
-    QVERIFY(cstr.isDetached());
+    QVERIFY(!cstr.isDetached());
     QVERIFY(cstr.constData() == ptr);
     QVERIFY(cstr == QString(ptr, 1));
     cstr.squeeze();
@@ -4036,7 +4036,7 @@ void tst_QString::setRawData()
     // This just tests the fromRawData() fallback
     QVERIFY(!cstr.isDetached());
     cstr.setRawData(ptr, 1);
-    QVERIFY(cstr.isDetached());
+    QVERIFY(!cstr.isDetached());
     QVERIFY(cstr.constData() == ptr);
     QVERIFY(cstr == QString(ptr, 1));
 
@@ -6571,7 +6571,7 @@ void tst_QString::literals()
     QVERIFY(str.length() == 4);
     QCOMPARE(str.capacity(), 0);
     QVERIFY(str == QLatin1String("abcd"));
-    QVERIFY(str.data_ptr()->isStatic());
+    QVERIFY(!str.data_ptr()->isMutable());
 
     const QChar *s = str.constData();
     QString str2 = str;
diff --git a/tests/auto/corelib/tools/qarraydata/simplevector.h b/tests/auto/corelib/tools/qarraydata/simplevector.h
index 94cee5d887..1a9ed35b7a 100644
--- a/tests/auto/corelib/tools/qarraydata/simplevector.h
+++ b/tests/auto/corelib/tools/qarraydata/simplevector.h
@@ -153,7 +153,7 @@ public:
             if (d->flags() & Data::CapacityReserved)
                 return;
             if (!d->isShared()) {
-                d->flags() |= Data::CapacityReserved;
+                d.setFlag(Data::CapacityReserved);
                 return;
             }
         }
@@ -338,10 +338,9 @@ public:
         d.detach();
     }
 
-    static SimpleVector fromRawData(const T *data, size_t size,
-            QArrayData::ArrayOptions options = Data::DefaultRawFlags)
+    static SimpleVector fromRawData(const T *data, size_t size)
     {
-        return SimpleVector(Data::fromRawData(data, size, options));
+        return SimpleVector(Data::fromRawData(data, size));
     }
 
 private:
diff --git a/tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp b/tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp
index 7b42b27f6e..128bc51553 100644
--- a/tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp
+++ b/tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp
@@ -156,20 +156,15 @@ void tst_QArrayData::sharedNullEmpty()
 
 void tst_QArrayData::simpleVector()
 {
-    QArrayData data0 = { Q_BASIC_ATOMIC_INITIALIZER(-1), QArrayData::StaticDataFlags, 0 };
-    QStaticArrayData<int, 7> data1 = {
-            { Q_BASIC_ATOMIC_INITIALIZER(-1), QArrayData::StaticDataFlags, 0 },
-            { 0, 1, 2, 3, 4, 5, 6 }
-        };
-
+    int data[] = { 0, 1, 2, 3, 4, 5, 6 };
     int array[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
 
     SimpleVector<int> v1;
     SimpleVector<int> v2(v1);
-    SimpleVector<int> v3(static_cast<QTypedArrayData<int> *>(&data0), 0, 0);
-    SimpleVector<int> v4(data1);
-    SimpleVector<int> v5(static_cast<QTypedArrayData<int> *>(&data0), 0, 0);
-    SimpleVector<int> v6(data1);
+    SimpleVector<int> v3(nullptr, nullptr, 0);
+    SimpleVector<int> v4(nullptr, data, 0);
+    SimpleVector<int> v5(nullptr, data, 1);
+    SimpleVector<int> v6(nullptr, data, 7);
     SimpleVector<int> v7(10, 5);
     SimpleVector<int> v8(array, array + sizeof(array)/sizeof(*array));
 
@@ -190,7 +185,7 @@ void tst_QArrayData::simpleVector()
     QVERIFY(v2.isEmpty());
     QVERIFY(v3.isEmpty());
     QVERIFY(v4.isEmpty());
-    QVERIFY(v5.isEmpty());
+    QVERIFY(!v5.isEmpty());
     QVERIFY(!v6.isEmpty());
     QVERIFY(!v7.isEmpty());
     QVERIFY(!v8.isEmpty());
@@ -199,7 +194,7 @@ void tst_QArrayData::simpleVector()
     QCOMPARE(v2.size(), size_t(0));
     QCOMPARE(v3.size(), size_t(0));
     QCOMPARE(v4.size(), size_t(0));
-    QCOMPARE(v5.size(), size_t(0));
+    QCOMPARE(v5.size(), size_t(1));
     QCOMPARE(v6.size(), size_t(7));
     QCOMPARE(v7.size(), size_t(10));
     QCOMPARE(v8.size(), size_t(10));
@@ -248,13 +243,13 @@ void tst_QArrayData::simpleVector()
     QVERIFY(v1 == v2);
     QVERIFY(v1 == v3);
     QVERIFY(v1 == v4);
-    QVERIFY(v1 == v5);
+    QVERIFY(v1 != v5);
     QVERIFY(!(v1 == v6));
 
     QVERIFY(v1 != v6);
     QVERIFY(v4 != v6);
     QVERIFY(v5 != v6);
-    QVERIFY(!(v1 != v5));
+    QVERIFY(!(v1 == v5));
 
     QVERIFY(v1 < v6);
     QVERIFY(!(v6 < v1));
@@ -428,17 +423,10 @@ void tst_QArrayData::simpleVectorReserve_data()
     QTest::newRow("empty") << SimpleVector<int>(0, 42) << size_t(0) << size_t(0);
     QTest::newRow("non-empty") << SimpleVector<int>(5, 42) << size_t(5) << size_t(5);
 
-    static const QStaticArrayData<int, 15> array = {
-        { Q_BASIC_ATOMIC_INITIALIZER(-1), QArrayData::StaticDataFlags, 0 },
-        { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 } };
-    const QArrayDataPointerRef<int> p = {
-         static_cast<QTypedArrayData<int> *>(
-            const_cast<QArrayData *>(&array.header)),
-        const_cast<int *>(array.data),
-        sizeof(array.data) / sizeof(array.data[0]) };
-
-    QTest::newRow("static") << SimpleVector<int>(p) << size_t(0) << size_t(15);
-    QTest::newRow("raw-data") << SimpleVector<int>::fromRawData(array.data, 15) << size_t(0) << size_t(15);
+    static const int array[] =
+        { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
+
+    QTest::newRow("raw-data") << SimpleVector<int>::fromRawData(array, 15) << size_t(0) << size_t(15);
 }
 
 void tst_QArrayData::simpleVectorReserve()
@@ -519,7 +507,7 @@ void tst_QArrayData::allocate_data()
     };
 
     QArrayData *shared_empty;
-    QArrayData::allocate(&shared_empty, 1, alignof(QArrayData), 0);
+    (void)QArrayData::allocate(&shared_empty, 1, alignof(QArrayData), 0);
     QVERIFY(shared_empty);
 
     struct {
@@ -1180,15 +1168,15 @@ void fromRawData_impl()
     {
         // Default: Immutable, sharable
         SimpleVector<T> raw = SimpleVector<T>::fromRawData(array,
-                sizeof(array)/sizeof(array[0]), QArrayData::DefaultRawFlags);
+                sizeof(array)/sizeof(array[0]));
 
         QCOMPARE(raw.size(), size_t(11));
         QCOMPARE((const T *)raw.constBegin(), array);
         QCOMPARE((const T *)raw.constEnd(), (const T *)(array + sizeof(array)/sizeof(array[0])));
 
-        QVERIFY(!raw.isShared());
+        QVERIFY(raw.isShared());
         QVERIFY(SimpleVector<T>(raw).isSharedWith(raw));
-        QVERIFY(!raw.isShared());
+        QVERIFY(raw.isShared());
 
         // Detach
         QCOMPARE(raw.back(), T(11));
diff --git a/tests/auto/corelib/tools/qlist/tst_qlist.cpp b/tests/auto/corelib/tools/qlist/tst_qlist.cpp
index df3f2023d6..ddf5e9c30a 100644
--- a/tests/auto/corelib/tools/qlist/tst_qlist.cpp
+++ b/tests/auto/corelib/tools/qlist/tst_qlist.cpp
@@ -336,6 +336,8 @@ private slots:
     void emplaceWithElementFromTheSameContainer();
     void emplaceWithElementFromTheSameContainer_data();
 
+    void fromReadOnlyData() const;
+
 private:
     template<typename T> void copyConstructor() const;
     template<typename T> void add() const;
@@ -2830,5 +2832,53 @@ void tst_QList::emplaceConsistentWithStdVectorImpl() const
     vecEq(qVec, stdVec);
 }
 
+void tst_QList::fromReadOnlyData() const
+{
+    {
+        QVector<char> d = QVector<char>::fromReadOnlyData("ABCDEFGHIJ");
+        QCOMPARE(d.size(), 10u + 1u);
+        for (int i = 0; i < 10; ++i)
+            QCOMPARE(d.data()[i], char('A' + i));
+    }
+
+    {
+        // wchar_t is not necessarily 2-bytes
+        QVector<wchar_t> d = QVector<wchar_t>::fromReadOnlyData(L"ABCDEFGHIJ");
+        QCOMPARE(d.size(), 10u + 1u);
+        for (int i = 0; i < 10; ++i)
+            QCOMPARE(d.data()[i], wchar_t('A' + i));
+        QVERIFY(d.isDetached());
+    }
+
+    {
+        const char data[] = "ABCDEFGHIJ";
+        const QVector<char> v = QVector<char>::fromReadOnlyData(data);
+
+        QVERIFY(v.constData() == data);
+        QVERIFY(!v.isEmpty());
+        QCOMPARE(v.size(), size_t(11));
+        // v.capacity() is unspecified, for now
+
+        QCOMPARE((void*)(const char*)(v.constBegin() + v.size()), (void*)(const char*)v.constEnd());
+
+        for (int i = 0; i < 10; ++i)
+            QCOMPARE(v[i], char('A' + i));
+        QCOMPARE(v[10], char('\0'));
+    }
+
+    {
+        struct LiteralType {
+            int value;
+            Q_DECL_CONSTEXPR LiteralType(int v = 0) : value(v) {}
+        };
+        const LiteralType literal[] = {LiteralType(0), LiteralType(1), LiteralType(2)};
+
+        const QVector<LiteralType> d = QVector<LiteralType>::fromReadOnlyData(literal);
+        QCOMPARE(d.size(), 3);
+        for (int i = 0; i < 3; ++i)
+            QCOMPARE(d.data()[i].value, i);
+    }
+}
+
 QTEST_MAIN(tst_QList)
 #include "tst_qlist.moc"
diff --git a/tests/auto/tools/qmakelib/tst_qmakelib.cpp b/tests/auto/tools/qmakelib/tst_qmakelib.cpp
index 3d66f940ff..a699a0575e 100644
--- a/tests/auto/tools/qmakelib/tst_qmakelib.cpp
+++ b/tests/auto/tools/qmakelib/tst_qmakelib.cpp
@@ -56,7 +56,7 @@ void tst_qmakelib::cleanupTestCase()
 
 void tst_qmakelib::proString()
 {
-    QString qs1(QStringLiteral("this is a string"));
+    QString qs1(QString::fromUtf8("this is a string"));
 
     ProString s1(qs1);
     QCOMPARE(s1.toQString(), QStringLiteral("this is a string"));