From 58058794b1379f153d28d844d5220298f21bcf96 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Wed, 22 Dec 2021 09:16:36 +0100
Subject: [PATCH] tst_qmetatype: fix memleaks

We didn't delete the new'ed up QMetaTypeInterfaces, causing asan to
complain.

Fix by storing them in strong references alongside their users in a
statically-allocated container.

We use shared_ptr to hold them, because QMetaTypeInterface doesn't
have a virtual destructor, so deleting objects of the TypeInfo types
(plural!) derived from QMetaTypeInterface though a pointer to the base
class is UB. The shared_ptr constructor, however, is templated, so it
stores the correct call (~TypeInfo()) in its type-erased deleter.

We can't use std::make_shared(), because that doesn't support
aggregate initialization until C++20, so we manually new up the
TypeInfos.

5.15 is not affected.

Pick-to: 6.3 6.2
Change-Id: Ic7ec88c34e02a9e0dd3421848c0c0885f4756702
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
---
 .../corelib/kernel/qmetatype/tst_qmetatype.cpp    | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp b/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
index d4ea231a7ed..740dcbc9bef 100644
--- a/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
+++ b/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
@@ -36,6 +36,7 @@
 
 #include <algorithm>
 #include <memory>
+#include <vector>
 
 Q_DECLARE_METATYPE(QMetaType::Type)
 
@@ -237,6 +238,12 @@ struct GenericPODType : BaseGenericType
     QByteArray podData;
 };
 
+// The order of the next two statics matters!
+//
+// need to use shared_ptr, for its template ctor, since QMetaTypeInterface isn't polymorphic,
+// but the test derives from it
+static std::vector<std::shared_ptr<QtPrivate::QMetaTypeInterface>> s_metaTypeInterfaces;
+
 using RegisteredType = QPair<std::shared_ptr<BaseGenericType>, std::shared_ptr<QMetaObject>>;
 static QHash<int, RegisteredType> s_managedTypes;
 
@@ -326,7 +333,7 @@ void tst_QMetaType::registerGadget(const char *name, const QList<GadgetPropertyT
         QMetaObject *mo;
     };
 
-    auto typeInfo = new TypeInfo {
+    auto typeInfo = s_metaTypeInterfaces.emplace_back(new TypeInfo {
         {
             0, alignof(GenericGadgetType), sizeof(GenericGadgetType), uint(flags), 0,
             [](const QtPrivate::QMetaTypeInterface *self) -> const QMetaObject * {
@@ -345,7 +352,7 @@ void tst_QMetaType::registerGadget(const char *name, const QList<GadgetPropertyT
             nullptr
         },
         meta
-    };
+    }).get();
     QMetaType gadgetMetaType(typeInfo);
     dynamicGadgetProperties->m_metatype = gadgetMetaType;
     int gadgetTypeId = QMetaType(typeInfo).id();
@@ -1241,7 +1248,7 @@ void tst_QMetaType::typedConstruct()
     dynamicGadgetProperties->podData = myPodTesData;
     const auto flags = QMetaType::NeedsConstruction | QMetaType::NeedsDestruction;
     using TypeInfo = QtPrivate::QMetaTypeInterface;
-    auto typeInfo = new TypeInfo {
+    auto typeInfo = s_metaTypeInterfaces.emplace_back(new TypeInfo {
         0, alignof(GenericGadgetType), sizeof(GenericGadgetType), uint(flags), 0, nullptr, podTypeName,
         [](const TypeInfo *self, void *where) { GadgetTypedConstructor(self->typeId, where, nullptr); },
         [](const TypeInfo *self, void *where, const void *copy) { GadgetTypedConstructor(self->typeId, where, copy); },
@@ -1253,7 +1260,7 @@ void tst_QMetaType::typedConstruct()
         GadgetSaveOperator,
         GadgetLoadOperator,
         nullptr
-    };
+    }).get();
     QMetaType metatype(typeInfo);
     dynamicGadgetProperties->m_metatype = metatype;
     int podTypeId = metatype.id();