From 66a1a71f1f92156548da487739129fb0f494c895 Mon Sep 17 00:00:00 2001
From: Christian Ehrlicher <ch.ehrlicher@gmx.de>
Date: Fri, 3 Feb 2023 17:31:11 +0100
Subject: [PATCH] Fix QVariant(QString) <-> enum conversion

A QVariant(QString) was not convertible to an enum not registered with
Q_ENUM() which worked fine in Qt5.
The same problem exists for QVariant(enum) to QString.
Fix it by not bailing out when no metatype for the enum was found and
try to convert it to a qlonglong instead (which is then correctly
converted to the enum type).

Fixes: QTBUG-109744
Pick-to: 6.5 6.4
Change-Id: Ie7bb016a860455b69508f0f46b36474c9c294f3a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/kernel/qmetatype.cpp                  | 15 ++++++++-------
 .../auto/corelib/kernel/qvariant/tst_qvariant.cpp |  7 +++++++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index 3606b298dd..139c4ec776 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -1947,7 +1947,6 @@ static bool convertFromEnum(QMetaType fromType, const void *from, QMetaType toTy
         if (toType.id() != QMetaType::QString && toType.id() != QMetaType::QByteArray)
             return QMetaType::convert(QMetaType::fromType<qlonglong>(), &ll, toType, to);
     }
-    Q_ASSERT(toType.id() == QMetaType::QString || toType.id() == QMetaType::QByteArray);
 #ifndef QT_NO_QOBJECT
     QMetaEnum en = metaEnumFromType(fromType);
     if (en.isValid()) {
@@ -1967,6 +1966,8 @@ static bool convertFromEnum(QMetaType fromType, const void *from, QMetaType toTy
         return true;
     }
 #endif
+    if (toType.id() == QMetaType::QString || toType.id() == QMetaType::QByteArray)
+        return QMetaType::convert(QMetaType::fromType<qlonglong>(), &ll, toType, to);
     return false;
 }
 
@@ -1978,12 +1979,12 @@ static bool convertToEnum(QMetaType fromType, const void *from, QMetaType toType
 #ifndef QT_NO_QOBJECT
     if (fromTypeId == QMetaType::QString || fromTypeId == QMetaType::QByteArray) {
         QMetaEnum en = metaEnumFromType(toType);
-        if (!en.isValid())
-            return false;
-        QByteArray keys = (fromTypeId == QMetaType::QString)
-                ? static_cast<const QString *>(from)->toUtf8()
-                : *static_cast<const QByteArray *>(from);
-        value = en.keysToValue(keys.constData(), &ok);
+        if (en.isValid()) {
+            QByteArray keys = (fromTypeId == QMetaType::QString)
+                    ? static_cast<const QString *>(from)->toUtf8()
+                    : *static_cast<const QByteArray *>(from);
+            value = en.keysToValue(keys.constData(), &ok);
+        }
     }
 #endif
     if (!ok) {
diff --git a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
index fbd17f94b2..87b9e20770 100644
--- a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
+++ b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
@@ -4982,6 +4982,13 @@ template <auto value> static void testVariantEnum()
     QVERIFY(var2.convert(QMetaType::fromType<int>()));
     QCOMPARE(var2.value<int>(), static_cast<int>(value));
 
+    QVariant strVar = QString::number(qToUnderlying(value));
+    QVariant baVar = QByteArray::number(qToUnderlying(value));
+    QCOMPARE(strVar.value<Enum>(), value);
+    QCOMPARE(baVar.value<Enum>(), value);
+    QCOMPARE(var.value<QString>(), strVar);
+    QCOMPARE(var.value<QByteArray>(), baVar);
+
     // unary + to silence gcc warning
     if (losslessConvertToInt) {
         int intValue = static_cast<int>(value);