From 3bc179c30d761f2ece11593218587954b763cf88 Mon Sep 17 00:00:00 2001
From: Ulf Hermann <ulf.hermann@qt.io>
Date: Mon, 15 Jan 2024 15:34:06 +0100
Subject: [PATCH] QMetaType: Assert on consistency when unregistering

If we are trying to unregister a metatype with an ID that belongs to a
different metatype, then something is very wrong.

Change-Id: I3191557883b69030f91c3aca7f359acf2dde66e7
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/kernel/qmetatype.cpp | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index 15a926fd465..a008485d8a2 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -907,13 +907,22 @@ bool QMetaType::isOrdered() const
 */
 void QMetaType::unregisterMetaType(QMetaType type)
 {
-    if (type.d_ptr && type.d_ptr->typeId.loadRelaxed() >= QMetaType::User) {
-        // this is a custom meta type (not read-only)
-        auto d = const_cast<QtPrivate::QMetaTypeInterface *>(type.d_ptr);
-        if (auto reg = customTypeRegistry())
-            reg->unregisterDynamicType(d->typeId.loadRelaxed());
-        d->typeId.storeRelease(0);
+    const QtPrivate::QMetaTypeInterface *d_ptr = type.d_ptr;
+    if (!d_ptr)
+        return;
+
+    const int typeId = d_ptr->typeId.loadRelaxed();
+    if (typeId < QMetaType::User)
+        return;
+
+    // this is a custom meta type (not read-only)
+
+    if (auto reg = customTypeRegistry()) {
+        Q_ASSERT(reg->getCustomType(typeId) == d_ptr);
+        reg->unregisterDynamicType(typeId);
     }
+
+    const_cast<QtPrivate::QMetaTypeInterface *>(d_ptr)->typeId.storeRelease(0);
 }
 
 /*!