Improve robustness of qml disk caching

Perform various basic checks before proceeding to load an existing cache file,
including the qt version, architecture, data structure version and others.

Change-Id: Ie822b056e944ac120643aad260e97f62616688bf
Reviewed-by: Erik Verbruggen <erik.verbruggen@qt.io>

13 files changed, 210 insertions, 37 deletions

diff --git a/src/qml/compiler/qv4compileddata.cpp b/src/qml/compiler/qv4compileddata.cpp
index 1bcd6892d2..965924262d 100644
--- a/src/qml/compiler/qv4compileddata.cpp
+++ b/src/qml/compiler/qv4compileddata.cpp
@@ -331,20 +331,56 @@ bool CompilationUnit::saveToDisk(QString *errorString)
     return true;
 }
 
-bool CompilationUnit::loadFromDisk(const QUrl &url, QString *errorString)
+bool CompilationUnit::loadFromDisk(const QUrl &url, EvalISelFactory *iselFactory, QString *errorString)
 {
     if (!url.isLocalFile()) {
         *errorString = QStringLiteral("File has to be a local file.");
         return false;
     }
 
-    QScopedPointer<QFile> cacheFile(new QFile(url.toLocalFile() + QLatin1Char('c')));
+    const QString sourcePath = url.toLocalFile();
+    QScopedPointer<QFile> cacheFile(new QFile(sourcePath + QLatin1Char('c')));
 
     if (!cacheFile->open(QIODevice::ReadOnly)) {
         *errorString = cacheFile->errorString();
         return false;
     }
 
+    {
+        CompiledData::Unit header;
+        qint64 bytesRead = cacheFile->read(reinterpret_cast<char *>(&header), sizeof(header));
+
+        if (bytesRead != sizeof(header)) {
+            *errorString = QStringLiteral("File too small for the header fields");
+            return false;
+        }
+
+        if (strncmp(header.magic, CompiledData::magic_str, sizeof(header.magic))) {
+            *errorString = QStringLiteral("Magic bytes in the header do not match");
+            return false;
+        }
+
+        if (header.version != quint32(QV4_DATA_STRUCTURE_VERSION)) {
+            *errorString = QString::fromUtf8("V4 data structure version mismatch. Found %1 expected %2").arg(header.version, 0, 16).arg(QV4_DATA_STRUCTURE_VERSION, 0, 16);
+            return false;
+        }
+
+        if (header.qtVersion != quint32(QT_VERSION)) {
+            *errorString = QString::fromUtf8("Qt version mismatch. Found %1 expected %2").arg(header.qtVersion, 0, 16).arg(QT_VERSION, 0, 16);
+            return false;
+        }
+
+        {
+            QFileInfo sourceCode(sourcePath);
+            if (sourceCode.exists() && sourceCode.lastModified().toMSecsSinceEpoch() != header.sourceTimeStamp) {
+                *errorString = QStringLiteral("QML source file has a different time stamp than cached file.");
+                return false;
+            }
+        }
+
+    }
+    // Data structure and qt version matched, so now we can access the rest of the file safely.
+
     uchar *cacheData = cacheFile->map(/*offset*/0, cacheFile->size());
     if (!cacheData) {
         *errorString = cacheFile->errorString();
@@ -354,13 +390,22 @@ bool CompilationUnit::loadFromDisk(const QUrl &url, QString *errorString)
     QScopedValueRollback<const Unit *> dataPtrChange(data, reinterpret_cast<const Unit *>(cacheData));
 
     {
-        QFileInfo sourceCode(url.toLocalFile());
-        if (sourceCode.exists() && sourceCode.lastModified().toMSecsSinceEpoch() != data->sourceTimeStamp) {
-            *errorString = QStringLiteral("QML source file has a different time stamp than cached file.");
+        const QString foundArchitecture = stringAt(data->architectureIndex);
+        const QString expectedArchitecture = QSysInfo::buildAbi();
+        if (foundArchitecture != expectedArchitecture) {
+            *errorString = QString::fromUtf8("Architecture mismatch. Found %1 expected %2").arg(foundArchitecture).arg(expectedArchitecture);
             return false;
         }
     }
 
+    {
+        const QString foundCodeGenerator = stringAt(data->codeGeneratorIndex);
+        const QString expectedCodeGenerator = iselFactory->codeGeneratorName;
+        if (foundCodeGenerator != expectedCodeGenerator) {
+            *errorString = QString::fromUtf8("Code generator mismatch. Found code generated by %1 but expected %2").arg(foundCodeGenerator).arg(expectedCodeGenerator);
+            return false;
+        }
+    }
 
     if (!memoryMapCode(errorString))
         return false;
diff --git a/src/qml/compiler/qv4compileddata_p.h b/src/qml/compiler/qv4compileddata_p.h
index 20b68026e9..4153259760 100644
--- a/src/qml/compiler/qv4compileddata_p.h
+++ b/src/qml/compiler/qv4compileddata_p.h
@@ -70,6 +70,9 @@
 
 QT_BEGIN_NAMESPACE
 
+// Bump this whenever the compiler data structures change in an incompatible way.
+#define QV4_DATA_STRUCTURE_VERSION 0x01
+
 class QIODevice;
 class QQmlPropertyCache;
 class QQmlPropertyData;
@@ -88,6 +91,7 @@ struct Function;
 }
 
 struct Function;
+class EvalISelFactory;
 
 namespace CompiledData {
 
@@ -597,11 +601,16 @@ static const char magic_str[] = "qv4cdata";
 
 struct Unit
 {
+    // DO NOT CHANGE THESE FIELDS EVER
     char magic[8];
-    LEInt16 architecture;
-    LEInt16 version;
+    LEUInt32 version;
+    LEUInt32 qtVersion;
     LEInt64 sourceTimeStamp;
     LEUInt32 unitSize; // Size of the Unit and any depending data.
+    // END DO NOT CHANGE THESE FIELDS EVER
+
+    LEUInt32 architectureIndex; // string index to QSysInfo::buildAbi()
+    LEUInt32 codeGeneratorIndex;
 
     enum : unsigned int {
         IsJavascript = 0x1,
@@ -880,7 +889,7 @@ struct Q_QML_PRIVATE_EXPORT CompilationUnit : public QQmlRefCount
     void destroy() Q_DECL_OVERRIDE;
 
     bool saveToDisk(QString *errorString);
-    bool loadFromDisk(const QUrl &url, QString *errorString);
+    bool loadFromDisk(const QUrl &url, EvalISelFactory *iselFactory, QString *errorString);
 
 protected:
     virtual void linkBackendToEngine(QV4::ExecutionEngine *engine) = 0;
diff --git a/src/qml/compiler/qv4compiler.cpp b/src/qml/compiler/qv4compiler.cpp
index 5d13734247..768a4ffcd3 100644
--- a/src/qml/compiler/qv4compiler.cpp
+++ b/src/qml/compiler/qv4compiler.cpp
@@ -352,17 +352,19 @@ void QV4::Compiler::JSUnitGenerator::writeFunction(char *f, QV4::IR::Function *i
     }
 }
 
-QV4::CompiledData::Unit QV4::Compiler::JSUnitGenerator::generateHeader(QV4::Compiler::JSUnitGenerator::GeneratorOption option, QJsonPrivate::q_littleendian<quint32> *functionOffsets, uint *jsClassDataOffset) const
+QV4::CompiledData::Unit QV4::Compiler::JSUnitGenerator::generateHeader(QV4::Compiler::JSUnitGenerator::GeneratorOption option, QJsonPrivate::q_littleendian<quint32> *functionOffsets, uint *jsClassDataOffset)
 {
     CompiledData::Unit unit;
     memcpy(unit.magic, CompiledData::magic_str, sizeof(unit.magic));
-    unit.architecture = 0; // ###
     unit.flags = QV4::CompiledData::Unit::IsJavascript;
-    unit.version = 1;
-    unit.functionTableSize = irModule->functions.size();
+    unit.version = QV4_DATA_STRUCTURE_VERSION;
+    unit.qtVersion = QT_VERSION;
+    unit.architectureIndex = registerString(QSysInfo::buildAbi());
+    unit.codeGeneratorIndex = registerString(codeGeneratorName);
 
     quint32 nextOffset = sizeof(CompiledData::Unit);
 
+    unit.functionTableSize = irModule->functions.size();
     unit.offsetToFunctionTable = nextOffset;
     nextOffset += unit.functionTableSize * sizeof(uint);
 
diff --git a/src/qml/compiler/qv4compiler_p.h b/src/qml/compiler/qv4compiler_p.h
index 4b67fe8600..49b8664513 100644
--- a/src/qml/compiler/qv4compiler_p.h
+++ b/src/qml/compiler/qv4compiler_p.h
@@ -118,8 +118,9 @@ struct Q_QML_PRIVATE_EXPORT JSUnitGenerator {
     void writeFunction(char *f, IR::Function *irFunction) const;
 
     StringTableGenerator stringTable;
+    QString codeGeneratorName;
 private:
-    CompiledData::Unit generateHeader(GeneratorOption option, QJsonPrivate::q_littleendian<quint32> *functionOffsets, uint *jsClassDataOffset) const;
+    CompiledData::Unit generateHeader(GeneratorOption option, QJsonPrivate::q_littleendian<quint32> *functionOffsets, uint *jsClassDataOffset);
 
     IR::Module *irModule;
 
diff --git a/src/qml/compiler/qv4instr_moth_p.h b/src/qml/compiler/qv4instr_moth_p.h
index e95a7f7046..112003ebb8 100644
--- a/src/qml/compiler/qv4instr_moth_p.h
+++ b/src/qml/compiler/qv4instr_moth_p.h
@@ -174,6 +174,8 @@ QT_BEGIN_NAMESPACE
 namespace QV4 {
 namespace Moth {
 
+    // When making changes to the instructions, make sure to bump QV4_DATA_STRUCTURE_VERSION in qv4compileddata_p.h
+
 struct Param {
     // Params are looked up as follows:
     // Constant: 0
diff --git a/src/qml/compiler/qv4isel_moth.cpp b/src/qml/compiler/qv4isel_moth.cpp
index 283948727b..dc803f1ee2 100644
--- a/src/qml/compiler/qv4isel_moth.cpp
+++ b/src/qml/compiler/qv4isel_moth.cpp
@@ -313,8 +313,8 @@ protected:
 };
 } // anonymous namespace
 
-InstructionSelection::InstructionSelection(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator)
-    : EvalInstructionSelection(execAllocator, module, jsGenerator)
+InstructionSelection::InstructionSelection(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator, EvalISelFactory *iselFactory)
+    : EvalInstructionSelection(execAllocator, module, jsGenerator, iselFactory)
     , qmlEngine(qmlEngine)
     , _block(0)
     , _codeStart(0)
diff --git a/src/qml/compiler/qv4isel_moth_p.h b/src/qml/compiler/qv4isel_moth_p.h
index eaca299c94..ea323497ef 100644
--- a/src/qml/compiler/qv4isel_moth_p.h
+++ b/src/qml/compiler/qv4isel_moth_p.h
@@ -80,7 +80,7 @@ class Q_QML_EXPORT InstructionSelection:
         public EvalInstructionSelection
 {
 public:
-    InstructionSelection(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator);
+    InstructionSelection(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator, EvalISelFactory *iselFactory);
     ~InstructionSelection();
 
     virtual void run(int functionIndex);
@@ -205,10 +205,11 @@ private:
 class Q_QML_EXPORT ISelFactory: public EvalISelFactory
 {
 public:
+    ISelFactory() : EvalISelFactory(QStringLiteral("moth")) {}
     virtual ~ISelFactory() {}
-    virtual EvalInstructionSelection *create(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator)
-    { return new InstructionSelection(qmlEngine, execAllocator, module, jsGenerator); }
-    virtual bool jitCompileRegexps() const
+    EvalInstructionSelection *create(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator) Q_DECL_OVERRIDE Q_DECL_FINAL
+    { return new InstructionSelection(qmlEngine, execAllocator, module, jsGenerator, this); }
+    bool jitCompileRegexps() const Q_DECL_OVERRIDE Q_DECL_FINAL
     { return false; }
     QQmlRefPointer<QV4::CompiledData::CompilationUnit> createUnitForLoading() Q_DECL_OVERRIDE;
 
diff --git a/src/qml/compiler/qv4isel_p.cpp b/src/qml/compiler/qv4isel_p.cpp
index 0ae08160ab..d97eec5e1d 100644
--- a/src/qml/compiler/qv4isel_p.cpp
+++ b/src/qml/compiler/qv4isel_p.cpp
@@ -52,7 +52,7 @@
 using namespace QV4;
 using namespace QV4::IR;
 
-EvalInstructionSelection::EvalInstructionSelection(QV4::ExecutableAllocator *execAllocator, Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator)
+EvalInstructionSelection::EvalInstructionSelection(QV4::ExecutableAllocator *execAllocator, Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator, EvalISelFactory *iselFactory)
     : useFastLookups(true)
     , useTypeInference(true)
     , executableAllocator(execAllocator)
@@ -67,6 +67,7 @@ EvalInstructionSelection::EvalInstructionSelection(QV4::ExecutableAllocator *exe
     Q_ASSERT(execAllocator);
 #endif
     Q_ASSERT(module);
+    jsGenerator->codeGeneratorName = iselFactory->codeGeneratorName;
 }
 
 EvalInstructionSelection::~EvalInstructionSelection()
diff --git a/src/qml/compiler/qv4isel_p.h b/src/qml/compiler/qv4isel_p.h
index d93c0893ae..a3fa80b6f0 100644
--- a/src/qml/compiler/qv4isel_p.h
+++ b/src/qml/compiler/qv4isel_p.h
@@ -65,13 +65,14 @@ class QQmlEnginePrivate;
 
 namespace QV4 {
 
+class EvalISelFactory;
 class ExecutableAllocator;
 struct Function;
 
 class Q_QML_PRIVATE_EXPORT EvalInstructionSelection
 {
 public:
-    EvalInstructionSelection(QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator);
+    EvalInstructionSelection(QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator, EvalISelFactory *iselFactory);
     virtual ~EvalInstructionSelection() = 0;
 
     QQmlRefPointer<QV4::CompiledData::CompilationUnit> compile(bool generateUnitData = true);
@@ -104,10 +105,13 @@ protected:
 class Q_QML_PRIVATE_EXPORT EvalISelFactory
 {
 public:
+    EvalISelFactory(const QString &codeGeneratorName) : codeGeneratorName(codeGeneratorName) {}
     virtual ~EvalISelFactory() = 0;
     virtual EvalInstructionSelection *create(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator) = 0;
     virtual bool jitCompileRegexps() const = 0;
     virtual QQmlRefPointer<QV4::CompiledData::CompilationUnit> createUnitForLoading() = 0;
+
+    const QString codeGeneratorName;
 };
 
 namespace IR {
diff --git a/src/qml/jit/qv4isel_masm.cpp b/src/qml/jit/qv4isel_masm.cpp
index bde2c59526..4066ab213c 100644
--- a/src/qml/jit/qv4isel_masm.cpp
+++ b/src/qml/jit/qv4isel_masm.cpp
@@ -258,8 +258,8 @@ JSC::MacroAssemblerCodeRef Assembler::link(int *codeSize)
     return codeRef;
 }
 
-InstructionSelection::InstructionSelection(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, Compiler::JSUnitGenerator *jsGenerator)
-    : EvalInstructionSelection(execAllocator, module, jsGenerator)
+InstructionSelection::InstructionSelection(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, Compiler::JSUnitGenerator *jsGenerator, EvalISelFactory *iselFactory)
+    : EvalInstructionSelection(execAllocator, module, jsGenerator, iselFactory)
     , _block(0)
     , _as(0)
     , compilationUnit(new CompilationUnit)
diff --git a/src/qml/jit/qv4isel_masm_p.h b/src/qml/jit/qv4isel_masm_p.h
index 7616ba147f..4b35a72e01 100644
--- a/src/qml/jit/qv4isel_masm_p.h
+++ b/src/qml/jit/qv4isel_masm_p.h
@@ -76,7 +76,7 @@ class Q_QML_EXPORT InstructionSelection:
         public EvalInstructionSelection
 {
 public:
-    InstructionSelection(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator);
+    InstructionSelection(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator, EvalISelFactory *iselFactory);
     ~InstructionSelection();
 
     virtual void run(int functionIndex);
@@ -285,12 +285,13 @@ private:
 class Q_QML_EXPORT ISelFactory: public EvalISelFactory
 {
 public:
+    ISelFactory() : EvalISelFactory(QStringLiteral("jit")) {}
     virtual ~ISelFactory() {}
-    virtual EvalInstructionSelection *create(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator)
-    { return new InstructionSelection(qmlEngine, execAllocator, module, jsGenerator); }
-    virtual bool jitCompileRegexps() const
+    EvalInstructionSelection *create(QQmlEnginePrivate *qmlEngine, QV4::ExecutableAllocator *execAllocator, IR::Module *module, QV4::Compiler::JSUnitGenerator *jsGenerator) Q_DECL_OVERRIDE Q_DECL_FINAL
+    { return new InstructionSelection(qmlEngine, execAllocator, module, jsGenerator, this); }
+    bool jitCompileRegexps() const Q_DECL_OVERRIDE Q_DECL_FINAL
     { return true; }
-    QQmlRefPointer<CompiledData::CompilationUnit> createUnitForLoading() Q_DECL_OVERRIDE;
+    QQmlRefPointer<CompiledData::CompilationUnit> createUnitForLoading() Q_DECL_OVERRIDE Q_DECL_FINAL;
 };
 
 } // end of namespace JIT
diff --git a/src/qml/qml/qqmltypeloader.cpp b/src/qml/qml/qqmltypeloader.cpp
index 52fed14ecb..851a18fa5f 100644
--- a/src/qml/qml/qqmltypeloader.cpp
+++ b/src/qml/qml/qqmltypeloader.cpp
@@ -2057,7 +2057,7 @@ bool QQmlTypeData::tryLoadFromDiskCache()
     QQmlRefPointer<QV4::CompiledData::CompilationUnit> unit = v4->iselFactory->createUnitForLoading();
     {
         QString error;
-        if (!unit->loadFromDisk(url(), &error)) {
+        if (!unit->loadFromDisk(url(), v4->iselFactory.data(), &error)) {
             qDebug() << "Error loading" << url().toString() << "from disk cache:" << error;
             return false;
         }
@@ -2840,7 +2840,7 @@ void QQmlScriptBlob::dataReceived(const Data &data)
     if (diskCache() && !forceDiskCacheRefresh()) {
         QQmlRefPointer<QV4::CompiledData::CompilationUnit> unit = v4->iselFactory->createUnitForLoading();
         QString error;
-        if (unit->loadFromDisk(url(), &error)) {
+        if (unit->loadFromDisk(url(), v4->iselFactory.data(), &error)) {
             initializeFromCompilationUnit(unit);
             return;
         } else {
diff --git a/tests/auto/qml/qmldiskcache/tst_qmldiskcache.cpp b/tests/auto/qml/qmldiskcache/tst_qmldiskcache.cpp
index bb78f2856f..1fe63bb99a 100644
--- a/tests/auto/qml/qmldiskcache/tst_qmldiskcache.cpp
+++ b/tests/auto/qml/qmldiskcache/tst_qmldiskcache.cpp
@@ -29,6 +29,11 @@
 #include <qtest.h>
 
 #include <private/qv4compileddata_p.h>
+#include <private/qv4compiler_p.h>
+#include <private/qv4jsir_p.h>
+#include <private/qv4isel_p.h>
+#include <private/qv8engine_p.h>
+#include <private/qv4engine_p.h>
 #include <QQmlComponent>
 #include <QQmlEngine>
 #include <QThread>
@@ -42,6 +47,7 @@ private slots:
 
     void regenerateAfterChange();
     void registerImportForImplicitComponent();
+    void basicVersionChecks();
 };
 
 struct TestCompiler
@@ -58,11 +64,8 @@ struct TestCompiler
 
     bool compile(const QByteArray &contents)
     {
-        if (currentMapping) {
-            mappedFile.unmap(currentMapping);
-            currentMapping = nullptr;
-        }
-        mappedFile.close();
+        closeMapping();
+        engine->clearComponentCache();
 
         // Qt API limits the precision of QFileInfo::modificationTime() to seconds, so to ensure that
         // the newly written file has a modification date newer than an existing cache file, we must
@@ -106,6 +109,44 @@ struct TestCompiler
         return unitPtr;
     }
 
+    typedef void (*HeaderTweakFunction)(QV4::CompiledData::Unit *header);
+    bool tweakHeader(HeaderTweakFunction function)
+    {
+        closeMapping();
+
+        QFile f(cacheFilePath);
+        if (!f.open(QIODevice::ReadWrite))
+            return false;
+        QV4::CompiledData::Unit header;
+        if (f.read(reinterpret_cast<char *>(&header), sizeof(header)) != sizeof(header))
+            return false;
+        function(&header);
+        f.seek(0);
+        return f.write(reinterpret_cast<const char *>(&header), sizeof(header)) == sizeof(header);
+    }
+
+    bool verify()
+    {
+        QV4::ExecutionEngine *v4 = QV8Engine::getV4(engine);
+        QQmlRefPointer<QV4::CompiledData::CompilationUnit> unit = v4->iselFactory->createUnitForLoading();
+        return unit->loadFromDisk(QUrl::fromLocalFile(testFilePath), v4->iselFactory.data(), &lastErrorString);
+    }
+
+    void closeMapping()
+    {
+        if (currentMapping) {
+            mappedFile.unmap(currentMapping);
+            currentMapping = nullptr;
+        }
+        mappedFile.close();
+    }
+
+    void clearCache()
+    {
+        closeMapping();
+        QFile::remove(cacheFilePath);
+    }
+
     QQmlEngine *engine;
     const QTemporaryDir tempDir;
     const QString testFilePath;
@@ -151,8 +192,6 @@ void tst_qmldiskcache::regenerateAfterChange()
         QVERIFY(bindingFunction->codeOffset > testUnit->unitSize);
     }
 
-    engine.clearComponentCache();
-
     {
         const QByteArray newContents = QByteArrayLiteral("import QtQml 2.0\n"
                                                          "QtObject {\n"
@@ -214,6 +253,74 @@ void tst_qmldiskcache::registerImportForImplicitComponent()
     }
 }
 
+void tst_qmldiskcache::basicVersionChecks()
+{
+    QQmlEngine engine;
+
+    TestCompiler testCompiler(&engine);
+    QVERIFY(testCompiler.tempDir.isValid());
+
+    const QByteArray contents = QByteArrayLiteral("import QtQml 2.0\n"
+                                                  "QtObject {\n"
+                                                   "    property string blah: Qt.platform;\n"
+                                                   "}");
+
+    {
+        testCompiler.clearCache();
+        QVERIFY2(testCompiler.compile(contents), qPrintable(testCompiler.lastErrorString));
+        QVERIFY2(testCompiler.verify(), qPrintable(testCompiler.lastErrorString));
+    }
+
+    {
+        testCompiler.clearCache();
+        QVERIFY2(testCompiler.compile(contents), qPrintable(testCompiler.lastErrorString));
+
+        testCompiler.tweakHeader([](QV4::CompiledData::Unit *header) {
+            header->qtVersion = 0;
+        });
+
+        QVERIFY(!testCompiler.verify());
+        QCOMPARE(testCompiler.lastErrorString, QString::fromUtf8("Qt version mismatch. Found 0 expected %1").arg(QT_VERSION, 0, 16));
+        testCompiler.clearCache();
+    }
+
+    {
+        testCompiler.clearCache();
+        QVERIFY2(testCompiler.compile(contents), qPrintable(testCompiler.lastErrorString));
+
+        testCompiler.tweakHeader([](QV4::CompiledData::Unit *header) {
+            header->version = 0;
+        });
+
+        QVERIFY(!testCompiler.verify());
+        QCOMPARE(testCompiler.lastErrorString, QString::fromUtf8("V4 data structure version mismatch. Found 0 expected %1").arg(QV4_DATA_STRUCTURE_VERSION, 0, 16));
+    }
+
+    {
+        testCompiler.clearCache();
+        QVERIFY2(testCompiler.compile(contents), qPrintable(testCompiler.lastErrorString));
+
+        testCompiler.tweakHeader([](QV4::CompiledData::Unit *header) {
+            header->architectureIndex = 0;
+        });
+
+        QVERIFY(!testCompiler.verify());
+        QCOMPARE(testCompiler.lastErrorString, QString::fromUtf8("Architecture mismatch. Found  expected %1").arg(QSysInfo::buildAbi()));
+    }
+
+    {
+        testCompiler.clearCache();
+        QVERIFY2(testCompiler.compile(contents), qPrintable(testCompiler.lastErrorString));
+
+        testCompiler.tweakHeader([](QV4::CompiledData::Unit *header) {
+            header->codeGeneratorIndex = 0;
+        });
+
+        QVERIFY(!testCompiler.verify());
+        QCOMPARE(testCompiler.lastErrorString, QString::fromUtf8("Code generator mismatch. Found code generated by  but expected %1").arg(QV8Engine::getV4(&engine)->iselFactory->codeGeneratorName));
+    }
+}
+
 QTEST_MAIN(tst_qmldiskcache)
 
 #include "tst_qmldiskcache.moc"