qmlcachegen: fix crash on unresolved type with required property

qmlcachegen can't resolve all types when importing QtQuick.Controls, so
scopes from QtQuick.Controls might be unresolved.
Check the scope before creating a fix suggesion when checking the
required properties, and add a test that tests a file with required
properties on an unresolved base type "Tumbler".

This also fixes the crashes from QTBUG-137196 and QTBUG-136998 it seems.

Pick-to: 6.10 6.9 6.8 6.5
Fixes: QTBUG-137411
Fixes: QTBUG-137196
Fixes: QTBUG-136998
Change-Id: Ibf461b54abf84ba13bff8c4833940c7359cf2d8e
Reviewed-by: Olivier De Cannière <olivier.decanniere@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/qmlcompiler/qqmljsimportvisitor.cpp

@@ -1055,16 +1055,17 @@ void QQmlJSImportVisitor::checkRequiredProperties()
                     : u"here"_s;
 
             if (!prevRequiredScope.isNull()) {
-                auto sourceScope = prevRequiredScope->baseType();
-                suggestion = QQmlJSFixSuggestion{
-                    "%1:%2:%3: Property marked as required in %4."_L1
-                            .arg(sourceScope->filePath())
-                            .arg(sourceScope->sourceLocation().startLine)
-                            .arg(sourceScope->sourceLocation().startColumn)
-                            .arg(requiredScopeName),
-                    sourceScope->sourceLocation()
-                };
-                suggestion->setFilename(sourceScope->filePath());
+                if (auto sourceScope = prevRequiredScope->baseType()) {
+                    suggestion = QQmlJSFixSuggestion{
+                        "%1:%2:%3: Property marked as required in %4."_L1
+                                .arg(sourceScope->filePath())
+                                .arg(sourceScope->sourceLocation().startLine)
+                                .arg(sourceScope->sourceLocation().startColumn)
+                                .arg(requiredScopeName),
+                        sourceScope->sourceLocation()
+                    };
+                    suggestion->setFilename(sourceScope->filePath());
+                }
             } else {
                 message += " (marked as required by %1)"_L1.arg(requiredScopeName);
             }

tests/auto/qml/qmlcachegen/data/crashes/buggyFixSuggestion.qml

@@ -0,0 +1,25 @@
+import QtQuick
+
+Item {
+    id: root
+
+    Item {
+        id: inner
+
+        Tumbler {
+            id: year
+
+            delegate: Rectangle {
+                required property var modelData
+            }
+        }
+
+        Tumbler {
+            id: month
+
+            delegate: Rectangle {
+                required property var modelData
+            }
+        }
+    }
+}

tests/auto/qml/qmlcachegen/tst_qmlcachegen.cpp

@@ -74,6 +74,9 @@ private slots:
     void aotstatsGeneration_data();
     void aotstatsGeneration();
     void aotstatsFormatRevisionMissmatch();
+
+    void crash_data();
+    void crash();
 };
 
 // A wrapper around QQmlComponent to ensure the temporary reference counts
@@ -122,6 +125,36 @@ static bool generateCache(const QString &qmlFileName, QByteArray *capturedStderr
     return proc.exitCode() == 0;
 }
 
+static bool generateCpp(const QString &qmlFileName, QByteArray *capturedStderr = nullptr)
+{
+#if defined(QTEST_CROSS_COMPILED)
+    QTest::qFail("You cannot call qmlcachegen on the target.", __FILE__, __LINE__);
+    return false;
+#endif
+    QProcess proc;
+    if (capturedStderr == nullptr)
+        proc.setProcessChannelMode(QProcess::ForwardedChannels);
+    proc.setProgram(QLibraryInfo::path(QLibraryInfo::LibraryExecutablesPath)
+                    + QLatin1String("/qmlcachegen"));
+    QTemporaryDir outputDir;
+    const QString outputFile = outputDir.filePath("output.cpp"_L1);
+    proc.setArguments(QStringList{ "--resource-path"_L1, "qrc:/qt/qml/Crashes/testFile.qml"_L1,
+                                   "-o"_L1, outputFile, qmlFileName });
+    proc.start();
+    if (!proc.waitForFinished())
+        return false;
+
+    if (capturedStderr)
+        *capturedStderr = proc.readAllStandardError();
+
+    if (!QFile::exists(outputFile))
+        return false;
+
+    if (proc.exitStatus() != QProcess::NormalExit)
+        return false;
+    return proc.exitCode() == 0;
+}
+
 tst_qmlcachegen::tst_qmlcachegen()
     : QQmlDataTest(QT_QMLTEST_DATADIR)
 {
@@ -1049,6 +1082,27 @@ void tst_qmlcachegen::aotstatsFormatRevisionMissmatch()
     QVERIFY(!QQmlJS::AotStats::fromJsonDocument(document).has_value());
 }
 
+void tst_qmlcachegen::crash_data()
+{
+    QTest::addColumn<QString>("fileName");
+
+    QTest::addRow("buggyFixSuggestion") << u"buggyFixSuggestion.qml"_s;
+}
+
+void tst_qmlcachegen::crash()
+{
+#if defined(QTEST_CROSS_COMPILED)
+    QSKIP("Cannot call qmlcachegen on cross-compiled target.");
+#endif
+
+    QFETCH(QString, fileName);
+    const QString filePath = testFile("crashes/" + fileName);
+
+    QFile file(filePath);
+    QVERIFY(file.exists());
+    QVERIFY(generateCpp(filePath));
+}
+
 const QQmlScriptString &ScriptStringProps::undef() const
 {
     return m_undef;