Fix memory leak with QtQuick compiler generated files

When for the QQC code path we do QML type re-compilation, we allocate a
new QV4::CompiledData::Unit. We must make sure that this dynamically
allocated memory is released in QV4::CompiledData::CompilationUnit's
destructor, by ensuring that the StaticData flag is not set.

This isn't directly applicable to the ahead-of-time generated cache file
unit data as they will always be re-generated (and thus the unsetting of
StaticData at the end of createCompilationUnit::createUnitData()), but
I've added a test-case nevertheless to ensure the correct engine
behavior.

Change-Id: I16973d7989567892bf8bf9dd6214bf293055d260
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 18 insertions, 0 deletions

diff --git a/tests/auto/qml/qmlcachegen/tst_qmlcachegen.cpp b/tests/auto/qml/qmlcachegen/tst_qmlcachegen.cpp
index b69071dd59..98a3a9d6ef 100644
--- a/tests/auto/qml/qmlcachegen/tst_qmlcachegen.cpp
+++ b/tests/auto/qml/qmlcachegen/tst_qmlcachegen.cpp
@@ -33,6 +33,7 @@
 #include <QProcess>
 #include <QLibraryInfo>
 #include <QSysInfo>
+#include <private/qqmlcomponent_p.h>
 
 class tst_qmlcachegen: public QObject
 {
@@ -114,6 +115,16 @@ void tst_qmlcachegen::loadGeneratedFile()
 
     const QString cacheFilePath = testFilePath + QLatin1Char('c');
     QVERIFY(QFile::exists(cacheFilePath));
+
+    {
+        QFile cache(cacheFilePath);
+        QVERIFY(cache.open(QIODevice::ReadOnly));
+        const QV4::CompiledData::Unit *cacheUnit = reinterpret_cast<const QV4::CompiledData::Unit *>(cache.map(/*offset*/0, sizeof(QV4::CompiledData::Unit)));
+        QVERIFY(cacheUnit);
+        QVERIFY(cacheUnit->flags & QV4::CompiledData::Unit::StaticData);
+        QVERIFY(cacheUnit->flags & QV4::CompiledData::Unit::PendingTypeCompilation);
+    }
+
     QVERIFY(QFile::remove(testFilePath));
 
     QQmlEngine engine;
@@ -121,6 +132,13 @@ void tst_qmlcachegen::loadGeneratedFile()
     QScopedPointer<QObject> obj(component.create());
     QVERIFY(!obj.isNull());
     QCOMPARE(obj->property("value").toInt(), 42);
+
+    auto componentPrivate = QQmlComponentPrivate::get(&component);
+    QVERIFY(componentPrivate);
+    auto compilationUnit = componentPrivate->compilationUnit;
+    QVERIFY(compilationUnit);
+    QVERIFY(compilationUnit->data);
+    QVERIFY(!(compilationUnit->data->flags & QV4::CompiledData::Unit::StaticData));
 }
 
 void tst_qmlcachegen::translationExpressionSupport()