QVariant: ensure the type custom is registered on construction

I must have broken this in the 6.5 work I did for QMetaType and
QVariant, but I haven't searched which commit exactly did it. Our
QVariant tests are old and thus only checked the type ID, which meant
that they caused the registration by the act of asking for the ID in the
first place; this commit adds a couple of explicit checks for the type
registered by name before the ID.

Fixes: QTBUG-112205
Change-Id: Idd5e1bb52be047d7b4fffffd174f1b14d90fd7a3
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit 8570e86fff183ffa4c1dff577c7fa14e3342daee)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 11 insertions, 0 deletions

diff --git a/src/corelib/kernel/qvariant.cpp b/src/corelib/kernel/qvariant.cpp
index c41f62e326..808dd43f08 100644
--- a/src/corelib/kernel/qvariant.cpp
+++ b/src/corelib/kernel/qvariant.cpp
@@ -874,6 +874,7 @@ QVariant::QVariant(const QVariant &p)
 */
 QVariant::QVariant(QMetaType type, const void *copy) : d(type.iface())
 {
+    type.registerType();
     if (isValidMetaTypeForVariant(type.iface(), copy))
         customConstruct(type.iface(), &d, copy);
     else
diff --git a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
index 9cf44ec76b..61a8e76156 100644
--- a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
+++ b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
@@ -1995,6 +1995,8 @@ void tst_QVariant::userType()
             QVariant userVar;
             userVar.setValue(data);
 
+            QVERIFY(QMetaType::fromName("MyType").isValid());
+            QCOMPARE(QMetaType::fromName("MyType"), QMetaType::fromType<MyType>());
             QVERIFY(userVar.typeId() > QMetaType::User);
             QCOMPARE(userVar.userType(), qMetaTypeId<MyType>());
             QCOMPARE(userVar.typeName(), "MyType");
@@ -2118,7 +2120,15 @@ void tst_QVariant::podUserType()
     pod.a = 10;
     pod.b = 20;
 
+    // one of these two must register the type
+    // (QVariant::fromValue calls QMetaType::fromType)
     QVariant pod_as_variant = QVariant::fromValue(pod);
+    QMetaType mt = QMetaType::fromType<MyTypePOD>();
+    QCOMPARE(pod_as_variant.metaType(), mt);
+    QCOMPARE(pod_as_variant.metaType().name(), mt.name());
+    QCOMPARE(QMetaType::fromName(mt.name()), mt);
+    QCOMPARE_NE(pod_as_variant.typeId(), 0);
+
     MyTypePOD pod2 = qvariant_cast<MyTypePOD>(pod_as_variant);
 
     QCOMPARE(pod.a, pod2.a);