Avoid copying QQmlJSScope

The factory should populate the pre-existing scope rather than copy it
into place. This way we can detect inheritance cycles involving the
pre-existing scope.

However, now we may detect the inheritance cycles earlier, when
resolving the types inside the lazy loading. We have the right pointers
available there now, after all. Therefore, add a way to propagate base
type errors out of the factory. When clearing the base type, we can now
give a reason for that. When checking the inheritance cycles we
retrieve that reason and log it.

We also remove the special casing of the ScopeType property of
QQmlJSScope. There is no real reason to set it in the ctor. As we
delay the population of QQmlJSScope now, we have to set it later.

Pick-to: 6.2 6.3
Task-number: QTBUG-102153
Change-Id: I49cf6e20f59fbdb6ed98a82040b3b159676f5975
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/qmlcompiler/qdeferredpointer_p.h

@@ -47,16 +47,25 @@
 QT_BEGIN_NAMESPACE
 
 template<typename T>
-class QDeferredFactory
+class QDeferredSharedPointer;
-{
-public:
-    T create() const;
-    bool isValid() const;
-};
 
 template<typename T>
 class QDeferredWeakPointer;
 
+template<typename T>
+class QDeferredFactory
+{
+public:
+    bool isValid() const;
+
+private:
+    friend class QDeferredSharedPointer<const T>;
+    friend class QDeferredWeakPointer<const T>;
+    friend class QDeferredSharedPointer<T>;
+    friend class QDeferredWeakPointer<T>;
+    void populate(const QSharedPointer<T> &) const;
+};
+
 template<typename T>
 class QDeferredSharedPointer
 {
@@ -179,7 +188,7 @@ private:
         if (Factory *f = factory()) {
             Factory localFactory;
             std::swap(localFactory, *f); // Swap before executing, to avoid recursion
-            const_cast<std::remove_const_t<T> &>(*m_data) = localFactory.create();
+            localFactory.populate(m_data.template constCast<std::remove_const_t<T>>());
         }
     }
 
@@ -245,8 +254,8 @@ private:
             if (factory->isValid()) {
                 Factory localFactory;
                 std::swap(localFactory, *factory); // Swap before executing, to avoid recursion
-                const_cast<std::remove_const_t<T> &>(*(m_data.toStrongRef()))
+                localFactory.populate(
-                        = localFactory.create();
+                        m_data.toStrongRef().template constCast<std::remove_const_t<T>>());
             }
         }
     }

src/qmlcompiler/qqmljscompiler.cpp

@@ -645,7 +645,8 @@ void QQmlJSAotCompiler::setDocument(
     m_logger->setCode(irDocument->code);
     m_unitGenerator = &irDocument->jsGenerator;
     m_entireSourceCodeLines = irDocument->code.split(u'\n');
-    QQmlJSImportVisitor visitor(m_importer, m_logger,
+    QQmlJSScope::Ptr target = QQmlJSScope::create();
+    QQmlJSImportVisitor visitor(target, m_importer, m_logger,
                                 resourcePathInfo.canonicalPath() + u'/',
                                 m_qmldirFiles);
     m_typeResolver.init(&visitor, irDocument->program);

src/qmlcompiler/qqmljsimportvisitor.cpp

@@ -74,15 +74,17 @@ inline QString getScopeName(const QQmlJSScope::ConstPtr &scope, QQmlJSScope::Sco
     return scope->baseTypeName();
 }
 
-QQmlJSImportVisitor::QQmlJSImportVisitor(QQmlJSImporter *importer, QQmlJSLogger *logger,
+QQmlJSImportVisitor::QQmlJSImportVisitor(
-                                         const QString &implicitImportDirectory,
+        const QQmlJSScope::Ptr &target, QQmlJSImporter *importer, QQmlJSLogger *logger,
-                                         const QStringList &qmldirFiles)
+        const QString &implicitImportDirectory, const QStringList &qmldirFiles)
     : m_implicitImportDirectory(implicitImportDirectory),
       m_qmldirFiles(qmldirFiles),
-      m_currentScope(QQmlJSScope::create(QQmlJSScope::JSFunctionScope)),
+      m_currentScope(QQmlJSScope::create()),
+      m_exportedRootScope(target),
       m_importer(importer),
       m_logger(logger)
 {
+    m_currentScope->setScopeType(QQmlJSScope::JSFunctionScope);
     Q_ASSERT(logger); // must be valid
 
     m_globalScope = m_currentScope;
@@ -116,10 +118,10 @@ QQmlJSImportVisitor::QQmlJSImportVisitor(QQmlJSImporter *importer, QQmlJSLogger
 
 QQmlJSImportVisitor::~QQmlJSImportVisitor() = default;
 
-void QQmlJSImportVisitor::enterEnvironment(QQmlJSScope::ScopeType type, const QString &name,
+void QQmlJSImportVisitor::populateCurrentScope(
-                                           const QQmlJS::SourceLocation &location)
+        QQmlJSScope::ScopeType type, const QString &name, const QQmlJS::SourceLocation &location)
 {
-    m_currentScope = QQmlJSScope::create(type, m_currentScope);
+    m_currentScope->setScopeType(type);
     setScopeName(m_currentScope, type, name);
     m_currentScope->setIsComposite(true);
     m_currentScope->setFilePath(QFileInfo(m_logger->fileName()).absoluteFilePath());
@@ -127,6 +129,22 @@ void QQmlJSImportVisitor::enterEnvironment(QQmlJSScope::ScopeType type, const QS
     m_scopesByIrLocation.insert({ location.startLine, location.startColumn }, m_currentScope);
 }
 
+void QQmlJSImportVisitor::enterRootScope(QQmlJSScope::ScopeType type, const QString &name, const QQmlJS::SourceLocation &location)
+{
+    QQmlJSScope::reparent(m_currentScope, m_exportedRootScope);
+    m_currentScope = m_exportedRootScope;
+    populateCurrentScope(type, name, location);
+}
+
+void QQmlJSImportVisitor::enterEnvironment(QQmlJSScope::ScopeType type, const QString &name,
+                                           const QQmlJS::SourceLocation &location)
+{
+    QQmlJSScope::Ptr newScope = QQmlJSScope::create();
+    QQmlJSScope::reparent(m_currentScope, newScope);
+    m_currentScope = std::move(newScope);
+    populateCurrentScope(type, name, location);
+}
+
 bool QQmlJSImportVisitor::enterEnvironmentNonUnique(QQmlJSScope::ScopeType type,
                                                     const QString &name,
                                                     const QQmlJS::SourceLocation &location)
@@ -295,11 +313,6 @@ void QQmlJSImportVisitor::resolveAliasesAndIds()
     }
 }
 
-QQmlJSScope::Ptr QQmlJSImportVisitor::result() const
-{
-    return m_exportedRootScope;
-}
-
 QString QQmlJSImportVisitor::implicitImportDirectory(
         const QString &localFile, QQmlJSResourceFileMapper *mapper)
 {
@@ -1048,28 +1061,34 @@ void QQmlJSImportVisitor::breakInheritanceCycles(const QQmlJSScope::Ptr &origina
         if (scopes.contains(scope)) {
             QString inheritenceCycle;
             for (const auto &seen : qAsConst(scopes)) {
-                if (!inheritenceCycle.isEmpty())
-                    inheritenceCycle.append(QLatin1String(" -> "));
                 inheritenceCycle.append(seen->baseTypeName());
+                inheritenceCycle.append(QLatin1String(" -> "));
             }
+            inheritenceCycle.append(scopes.first()->baseTypeName());
 
-            m_logger->log(QStringLiteral("%1 is part of an inheritance cycle: %2")
+            const QString message = QStringLiteral("%1 is part of an inheritance cycle: %2")
-                                  .arg(scope->internalName())
+                                            .arg(scope->internalName(), inheritenceCycle);
-                                  .arg(inheritenceCycle),
+            m_logger->log(message, Log_InheritanceCycle, scope->sourceLocation());
-                          Log_InheritanceCycle, scope->sourceLocation());
             originalScope->clearBaseType();
+            originalScope->setBaseTypeError(message);
             break;
         }
 
         scopes.append(scope);
 
         const auto newScope = scope->baseType();
-        if (newScope.isNull() && !scope->baseTypeName().isEmpty()) {
+        if (newScope.isNull()) {
-            m_logger->log(scope->baseTypeName()
+            const QString error = scope->baseTypeError();
-                                  + QStringLiteral(" was not found. Did you add all import paths?"),
+            const QString name = scope->baseTypeName();
-                          Log_Import, scope->sourceLocation(), true, true,
+            if (!error.isEmpty()) {
-                          QQmlJSUtils::didYouMean(scope->baseTypeName(), m_rootScopeImports.keys(),
+                m_logger->log(error, Log_Import, scope->sourceLocation(), true, true);
-                                                  scope->sourceLocation()));
+            } else if (!name.isEmpty()) {
+                m_logger->log(
+                        name + QStringLiteral(" was not found. Did you add all import paths?"),
+                        Log_Import, scope->sourceLocation(), true, true,
+                        QQmlJSUtils::didYouMean(scope->baseTypeName(), m_rootScopeImports.keys(),
+                                                scope->sourceLocation()));
+            }
         }
 
         scope = newScope;
@@ -1206,10 +1225,11 @@ bool QQmlJSImportVisitor::visit(UiObjectDefinition *definition)
 
     Q_ASSERT(!superType.isEmpty());
     if (superType.front().isUpper()) {
-        enterEnvironment(QQmlJSScope::QMLScope, superType, definition->firstSourceLocation());
+        if (rootScopeIsValid()) {
-        if (!m_exportedRootScope) {
+            enterEnvironment(QQmlJSScope::QMLScope, superType, definition->firstSourceLocation());
-            m_exportedRootScope = m_currentScope;
+        } else {
-            m_exportedRootScope->setIsSingleton(m_rootIsSingleton);
+            enterRootScope(QQmlJSScope::QMLScope, superType, definition->firstSourceLocation());
+            m_currentScope->setIsSingleton(m_rootIsSingleton);
         }
 
         const QTypeRevision revision = QQmlJSScope::resolveTypes(
@@ -1223,7 +1243,7 @@ bool QQmlJSImportVisitor::visit(UiObjectDefinition *definition)
     } else {
         enterEnvironmentNonUnique(QQmlJSScope::GroupedPropertyScope, superType,
                                   definition->firstSourceLocation());
-        Q_ASSERT(m_exportedRootScope);
+        Q_ASSERT(rootScopeIsValid());
         QQmlJSScope::resolveTypes(m_currentScope, m_rootScopeImports, &m_usedTypes);
     }
 
@@ -2118,7 +2138,7 @@ void QQmlJSImportVisitor::endVisit(QQmlJS::AST::UiObjectBinding *uiob)
 
 bool QQmlJSImportVisitor::visit(ExportDeclaration *)
 {
-    Q_ASSERT(!m_exportedRootScope.isNull());
+    Q_ASSERT(rootScopeIsValid());
     Q_ASSERT(m_exportedRootScope != m_globalScope);
     Q_ASSERT(m_currentScope == m_globalScope);
     m_currentScope = m_exportedRootScope;
@@ -2127,18 +2147,17 @@ bool QQmlJSImportVisitor::visit(ExportDeclaration *)
 
 void QQmlJSImportVisitor::endVisit(ExportDeclaration *)
 {
-    Q_ASSERT(!m_exportedRootScope.isNull());
+    Q_ASSERT(rootScopeIsValid());
     m_currentScope = m_exportedRootScope->parentScope();
     Q_ASSERT(m_currentScope == m_globalScope);
 }
 
 bool QQmlJSImportVisitor::visit(ESModule *module)
 {
-    enterEnvironment(QQmlJSScope::JSLexicalScope, QStringLiteral("module"),
+    Q_ASSERT(!rootScopeIsValid());
-                     module->firstSourceLocation());
+    enterRootScope(
-    Q_ASSERT(m_exportedRootScope.isNull());
+            QQmlJSScope::JSLexicalScope, QStringLiteral("module"), module->firstSourceLocation());
-    m_exportedRootScope = m_currentScope;
+    m_currentScope->setIsScript(true);
-    m_exportedRootScope->setIsScript(true);
     importBaseModules();
     leaveEnvironment();
     return true;
@@ -2152,9 +2171,10 @@ void QQmlJSImportVisitor::endVisit(ESModule *)
 bool QQmlJSImportVisitor::visit(Program *)
 {
     Q_ASSERT(m_globalScope == m_currentScope);
-    Q_ASSERT(m_exportedRootScope.isNull());
+    Q_ASSERT(!rootScopeIsValid());
-    m_exportedRootScope = m_currentScope;
+    *m_exportedRootScope = std::move(*QQmlJSScope::clone(m_currentScope));
     m_exportedRootScope->setIsScript(true);
+    m_currentScope = m_exportedRootScope;
     importBaseModules();
     return true;
 }

src/qmlcompiler/qqmljsimportvisitor_p.h

@@ -61,12 +61,13 @@ struct QQmlJSResourceFileMapper;
 class Q_QMLCOMPILER_PRIVATE_EXPORT QQmlJSImportVisitor : public QQmlJS::AST::Visitor
 {
 public:
-    QQmlJSImportVisitor(QQmlJSImporter *importer, QQmlJSLogger *logger,
+    QQmlJSImportVisitor(const QQmlJSScope::Ptr &target,
+                        QQmlJSImporter *importer, QQmlJSLogger *logger,
                         const QString &implicitImportDirectory,
                         const QStringList &qmldirFiles = QStringList());
     ~QQmlJSImportVisitor();
 
-    QQmlJSScope::Ptr result() const;
+    QQmlJSScope::Ptr result() const { return m_exportedRootScope; }
 
     QQmlJSLogger *logger() { return m_logger; }
 
@@ -161,7 +162,7 @@ protected:
     QStringList m_qmldirFiles;
     QQmlJSScope::Ptr m_currentScope;
     QQmlJSScope::Ptr m_savedBindingOuterScope;
-    QQmlJSScope::Ptr m_exportedRootScope;
+    const QQmlJSScope::Ptr m_exportedRootScope;
     QQmlJSScope::ConstPtr m_globalScope;
     QQmlJSScopesById m_scopesById;
     QQmlJSImporter::ImportedTypes m_rootScopeImports;
@@ -226,6 +227,7 @@ protected:
     void breakInheritanceCycles(const QQmlJSScope::Ptr &scope);
     void checkDeprecation(const QQmlJSScope::ConstPtr &scope);
     void checkGroupedAndAttachedScopes(QQmlJSScope::ConstPtr scope);
+    bool rootScopeIsValid() const { return m_exportedRootScope->sourceLocation().isValid(); }
 
     QQmlJSLogger *m_logger;
     enum class LiteralOrScriptParseResult { Invalid, Script, Literal };
@@ -300,6 +302,10 @@ private:
             const QString &what,
             const QQmlJS::SourceLocation &srcLocation = QQmlJS::SourceLocation());
     void addImportWithLocation(const QString &name, const QQmlJS::SourceLocation &loc);
+    void populateCurrentScope(QQmlJSScope::ScopeType type, const QString &name,
+                              const QQmlJS::SourceLocation &location);
+    void enterRootScope(QQmlJSScope::ScopeType type, const QString &name,
+                           const QQmlJS::SourceLocation &location);
 };
 
 QT_END_NAMESPACE

src/qmlcompiler/qqmljslinter.cpp

@@ -311,7 +311,8 @@ QQmlJSLinter::LintResult QQmlJSLinter::lintFile(const QString &filename,
             m_logger->setFileName(m_useAbsolutePath ? info.absoluteFilePath() : filename);
             m_logger->setCode(code);
             m_logger->setSilent(silent || json);
-            QQmlJSImportVisitor v { &m_importer, m_logger.get(),
+            QQmlJSScope::Ptr target = QQmlJSScope::create();
+            QQmlJSImportVisitor v { target, &m_importer, m_logger.get(),
                                     QQmlJSImportVisitor::implicitImportDirectory(
                                             m_logger->fileName(), m_importer.resourceFileMapper()),
                                     qmldirFiles };

src/qmlcompiler/qqmljsscope.cpp

@@ -92,23 +92,23 @@ static bool searchBaseAndExtensionTypes(QQmlJSScopePtr type, const Action &check
     return false;
 }
 
-QQmlJSScope::QQmlJSScope(ScopeType type, const QQmlJSScope::Ptr &parentScope)
+void QQmlJSScope::reparent(const QQmlJSScope::Ptr &parentScope, const QQmlJSScope::Ptr &childScope)
-    : m_parentScope(parentScope), m_scopeType(type) {}
-
-QQmlJSScope::Ptr QQmlJSScope::create(ScopeType type, const QQmlJSScope::Ptr &parentScope)
 {
-    QSharedPointer<QQmlJSScope> childScope(new QQmlJSScope{type, parentScope});
+    if (const QQmlJSScope::Ptr parent = childScope->m_parentScope.toStrongRef())
+        parent->m_childScopes.removeOne(childScope);
     if (parentScope)
-        parentScope->m_childScopes.push_back(childScope);
+        parentScope->m_childScopes.append(childScope);
-    return childScope;
+    childScope->m_parentScope = parentScope;
 }
 
 QQmlJSScope::Ptr QQmlJSScope::clone(const ConstPtr &origin)
 {
     if (origin.isNull())
         return QQmlJSScope::Ptr();
-    QQmlJSScope::Ptr cloned = create(origin->m_scopeType, origin->m_parentScope);
+    QQmlJSScope::Ptr cloned = create();
     *cloned = *origin;
+    if (QQmlJSScope::Ptr parent = cloned->parentScope())
+        parent->m_childScopes.append(cloned);
     return cloned;
 }
 
@@ -382,8 +382,9 @@ QTypeRevision QQmlJSScope::resolveType(
         const QQmlJSScope::Ptr &self, const QQmlJSScope::ContextualTypes &context,
         QSet<QString> *usedTypes)
 {
-    const auto baseType = findType(self->m_baseTypeName, context, usedTypes);
+    const QString baseTypeName = self->baseTypeName();
-    if (!self->m_baseType.scope && !self->m_baseTypeName.isEmpty())
+    const auto baseType = findType(baseTypeName, context, usedTypes);
+    if (!self->m_baseType.scope && !baseTypeName.isEmpty())
         self->m_baseType = { baseType.scope, baseType.revision };
 
     if (!self->m_attachedType && !self->m_attachedTypeName.isEmpty())
@@ -447,7 +448,7 @@ void QQmlJSScope::updateChildScope(
             const auto propertyIt = type->m_properties.find(childScope->internalName());
             if (propertyIt != type->m_properties.end()) {
                 childScope->m_baseType.scope = QQmlJSScope::ConstPtr(propertyIt->type());
-                childScope->m_baseTypeName = propertyIt->typeName();
+                childScope->setBaseTypeName(propertyIt->typeName());
                 return true;
             }
             return false;
@@ -457,7 +458,7 @@ void QQmlJSScope::updateChildScope(
         if (const auto attachedBase = findType(
                     childScope->internalName(), contextualTypes, usedTypes).scope) {
             childScope->m_baseType.scope = attachedBase->attachedType();
-            childScope->m_baseTypeName = attachedBase->attachedTypeName();
+            childScope->setBaseTypeName(attachedBase->attachedTypeName());
         }
         break;
     default:
@@ -508,8 +509,10 @@ void QQmlJSScope::resolveEnums(const QQmlJSScope::Ptr &self, const QQmlJSScope::
         if (it->type())
             continue;
         Q_ASSERT(intType); // We need an "int" type to resolve enums
-        auto enumScope = QQmlJSScope::create(EnumScope, self);
+        QQmlJSScope::Ptr enumScope = QQmlJSScope::create();
-        enumScope->m_baseTypeName = QStringLiteral("int");
+        reparent(self, enumScope);
+        enumScope->m_scopeType = EnumScope;
+        enumScope->setBaseTypeName(QStringLiteral("int"));
         enumScope->m_baseType.scope = intType;
         enumScope->m_semantics = AccessSemantics::Value;
         enumScope->m_internalName = self->internalName() + QStringLiteral("::") + it->name();
@@ -761,6 +764,28 @@ bool QQmlJSScope::isNameDeferred(const QString &name) const
     return isDeferred;
 }
 
+void QQmlJSScope::setBaseTypeName(const QString &baseTypeName)
+{
+    m_flags.setFlag(HasBaseTypeError, false);
+    m_baseTypeNameOrError = baseTypeName;
+}
+
+QString QQmlJSScope::baseTypeName() const
+{
+    return m_flags.testFlag(HasBaseTypeError) ? QString() : m_baseTypeNameOrError;
+}
+
+void QQmlJSScope::setBaseTypeError(const QString &baseTypeError)
+{
+    m_flags.setFlag(HasBaseTypeError);
+    m_baseTypeNameOrError = baseTypeError;
+}
+
+QString QQmlJSScope::baseTypeError() const
+{
+    return m_flags.testFlag(HasBaseTypeError) ? m_baseTypeNameOrError : QString();
+}
+
 QString QQmlJSScope::attachedTypeName() const
 {
     QString name;
@@ -792,7 +817,7 @@ bool QQmlJSScope::isResolved() const
     const bool nameIsEmpty = (m_scopeType == ScopeType::AttachedPropertyScope
                               || m_scopeType == ScopeType::GroupedPropertyScope)
             ? m_internalName.isEmpty()
-            : m_baseTypeName.isEmpty();
+            : m_baseTypeNameOrError.isEmpty();
     if (nameIsEmpty)
         return true;
     if (m_baseType.scope.isNull())
@@ -865,31 +890,29 @@ bool QQmlJSScope::Export::isValid() const
     return m_version.isValid() || !m_package.isEmpty() || !m_type.isEmpty();
 }
 
-QQmlJSScope QDeferredFactory<QQmlJSScope>::create() const
+void QDeferredFactory<QQmlJSScope>::populate(const QSharedPointer<QQmlJSScope> &scope) const
 {
     QQmlJSTypeReader typeReader(m_importer, m_filePath);
-    QQmlJSScope::Ptr result = typeReader();
+    typeReader(scope);
     m_importer->m_globalWarnings.append(typeReader.errors());
-    result->setInternalName(internalName());
+    scope->setInternalName(internalName());
-    QQmlJSScope::resolveEnums(result, m_importer->builtinInternalNames().value(u"int"_qs).scope);
+    QQmlJSScope::resolveEnums(scope, m_importer->builtinInternalNames().value(u"int"_qs).scope);
 
-    if (m_isSingleton && !result->isSingleton()) {
+    if (m_isSingleton && !scope->isSingleton()) {
         m_importer->m_globalWarnings.append(
                 { QStringLiteral(
                           "Type %1 declared as singleton in qmldir but missing pragma Singleton")
-                          .arg(result->internalName()),
+                          .arg(scope->internalName()),
                   QtCriticalMsg, QQmlJS::SourceLocation() });
-        result->setIsSingleton(true);
+        scope->setIsSingleton(true);
-    } else if (!m_isSingleton && result->isSingleton()) {
+    } else if (!m_isSingleton && scope->isSingleton()) {
         m_importer->m_globalWarnings.append(
                 { QStringLiteral("Type %1 not declared as singleton in qmldir "
                                  "but using pragma Singleton")
-                          .arg(result->internalName()),
+                          .arg(scope->internalName()),
                   QtCriticalMsg, QQmlJS::SourceLocation() });
-        result->setIsSingleton(false);
+        scope->setIsSingleton(false);
     }
-
-    return std::move(*result);
 }
 
 bool QQmlJSScope::canAssign(const QQmlJSScope::ConstPtr &derived) const

src/qmlcompiler/qqmljsscope_p.h

@@ -95,7 +95,8 @@ public:
         CustomParser = 0x10,
         Array = 0x20,
         InlineComponent = 0x40,
-        WrappedInImplicitComponent = 0x80
+        WrappedInImplicitComponent = 0x80,
+        HasBaseTypeError = 0x100
     };
     Q_DECLARE_FLAGS(Flags, Flag)
     Q_FLAGS(Flags);
@@ -241,8 +242,7 @@ public:
         UnnamedPropertyTarget // default property bindings, where property name is unspecified
     };
 
-    static QQmlJSScope::Ptr create(ScopeType type = QQmlJSScope::QMLScope,
+    static QQmlJSScope::Ptr create() { return QSharedPointer<QQmlJSScope>(new QQmlJSScope); }
-                                   const QQmlJSScope::Ptr &parentScope = QQmlJSScope::Ptr());
     static QQmlJSScope::Ptr clone(const QQmlJSScope::ConstPtr &origin);
     static QQmlJSScope::ConstPtr findCurrentQMLScope(const QQmlJSScope::ConstPtr &scope);
 
@@ -256,6 +256,8 @@ public:
         return QQmlJSScope::WeakConstPtr(m_parentScope).toStrongRef();
     }
 
+    static void reparent(const QQmlJSScope::Ptr &parentScope, const QQmlJSScope::Ptr &childScope);
+
     void insertJSIdentifier(const QString &name, const JavaScriptIdentifier &identifier);
 
     // inserts property as qml identifier as well as the corresponding
@@ -264,6 +266,7 @@ public:
     bool isIdInCurrentScope(const QString &id) const;
 
     ScopeType scopeType() const { return m_scopeType; }
+    void setScopeType(ScopeType type) { m_scopeType = type; }
 
     void addOwnMethod(const QQmlJSMetaMethod &method) { m_methods.insert(method.methodName(), method); }
     QMultiHash<QString, QQmlJSMetaMethod> ownMethods() const { return m_methods; }
@@ -322,11 +325,15 @@ public:
 
     // If isComposite(), this is the QML/JS name of the prototype. Otherwise it's the
     // relevant base class (in the hierarchy starting from QObject) of a C++ type.
-    void setBaseTypeName(const QString &baseTypeName) { m_baseTypeName = baseTypeName; }
+    void setBaseTypeName(const QString &baseTypeName);
-    QString baseTypeName() const { return m_baseTypeName; }
+    QString baseTypeName() const;
+
     QQmlJSScope::ConstPtr baseType() const { return m_baseType.scope; }
     QTypeRevision baseTypeRevision() const { return m_baseType.revision; }
+
     void clearBaseType() { m_baseType = {}; }
+    void setBaseTypeError(const QString &baseTypeError);
+    QString baseTypeError() const;
 
     void addOwnProperty(const QQmlJSMetaProperty &prop) { m_properties.insert(prop.propertyName(), prop); }
     QHash<QString, QQmlJSMetaProperty> ownProperties() const { return m_properties; }
@@ -552,7 +559,7 @@ public:
     };
 
 private:
-    QQmlJSScope(ScopeType type, const QQmlJSScope::Ptr &parentScope = QQmlJSScope::Ptr());
+    QQmlJSScope() = default;
     QQmlJSScope(const QQmlJSScope &) = default;
     QQmlJSScope &operator=(const QQmlJSScope &) = default;
 
@@ -587,7 +594,7 @@ private:
 
     QString m_filePath;
     QString m_internalName;
-    QString m_baseTypeName;
+    QString m_baseTypeNameOrError;
 
     // We only need the revision for the base type as inheritance is
     // the only relation between two types where the revisions matter.
@@ -627,8 +634,6 @@ public:
         m_filePath(filePath), m_importer(importer)
     {}
 
-    QQmlJSScope create() const;
-
     bool isValid() const
     {
         return !m_filePath.isEmpty() && m_importer != nullptr;
@@ -645,6 +650,14 @@ public:
     }
 
 private:
+    friend class QDeferredSharedPointer<QQmlJSScope>;
+    friend class QDeferredSharedPointer<const QQmlJSScope>;
+    friend class QDeferredWeakPointer<QQmlJSScope>;
+    friend class QDeferredWeakPointer<const QQmlJSScope>;
+
+    // Should only be called when lazy-loading the type in a deferred pointer.
+    void populate(const QSharedPointer<QQmlJSScope> &scope) const;
+
     QString m_filePath;
     QQmlJSImporter *m_importer = nullptr;
     bool m_isSingleton = false;

src/qmlcompiler/qqmljstypereader.cpp

@@ -40,13 +40,13 @@
 
 QT_BEGIN_NAMESPACE
 
-QQmlJSScope::Ptr QQmlJSTypeReader::operator()()
+bool QQmlJSTypeReader::operator ()(const QSharedPointer<QQmlJSScope> &scope)
 {
     using namespace QQmlJS::AST;
     const QFileInfo info { m_file };
-    QString baseName = info.baseName();
+    const QString baseName = info.baseName();
-    const QString scopeName = baseName.endsWith(QStringLiteral(".ui")) ? baseName.chopped(3)
+    scope->setInternalName(baseName.endsWith(QStringLiteral(".ui")) ? baseName.chopped(3)
-                                                                       : baseName;
+                                                                    : baseName);
 
     QQmlJS::Engine engine;
     QQmlJS::Lexer lexer(&engine);
@@ -55,16 +55,10 @@ QQmlJSScope::Ptr QQmlJSTypeReader::operator()()
     const bool isESModule = lowerSuffix == QLatin1String("mjs");
     const bool isJavaScript = isESModule || lowerSuffix == QLatin1String("js");
 
-    auto errorResult = [&](){
-        QQmlJSScope::Ptr result = QQmlJSScope::create(
-                    isJavaScript ? QQmlJSScope::JSLexicalScope : QQmlJSScope::QMLScope);
-        result->setInternalName(scopeName);
-        return result;
-    };
 
     QFile file(m_file);
     if (!file.open(QFile::ReadOnly))
-        return errorResult();
+        return false;
 
     QString code = QString::fromUtf8(file.readAll());
     file.close();
@@ -76,11 +70,11 @@ QQmlJSScope::Ptr QQmlJSTypeReader::operator()()
                                                     : parser.parseProgram())
                                       : parser.parse();
     if (!success)
-        return errorResult();
+        return false;
 
     QQmlJS::AST::Node *rootNode = parser.rootNode();
     if (!rootNode)
-        return errorResult();
+        return false;
 
     QQmlJSLogger logger;
     logger.setFileName(m_file);
@@ -88,13 +82,10 @@ QQmlJSScope::Ptr QQmlJSTypeReader::operator()()
     logger.setSilent(true);
 
     QQmlJSImportVisitor membersVisitor(
-            m_importer, &logger,
+            scope, m_importer, &logger,
             QQmlJSImportVisitor::implicitImportDirectory(m_file, m_importer->resourceFileMapper()));
     rootNode->accept(&membersVisitor);
-    auto result = membersVisitor.result();
+    return true;
-    Q_ASSERT(result);
-    result->setInternalName(scopeName);
-    return result;
 }
 
 QT_END_NAMESPACE

src/qmlcompiler/qqmljstypereader_p.h

@@ -59,7 +59,7 @@ public:
         , m_file(file)
     {}
 
-    QQmlJSScope::Ptr operator()();
+    bool operator()(const QSharedPointer<QQmlJSScope> &scope);
     QList<QQmlJS::DiagnosticMessage> errors() const { return m_errors; }
 
 private:

tests/auto/qml/qmllint/data/cycleHead.qml

@@ -2,5 +2,6 @@ import Cycle
 import QtQuick
 
 Item {
-    MenuItem {}
+    property MenuItem item: a
+    MenuItem { id: a }
 }

tests/auto/qml/qmllint/tst_qmllint.cpp

@@ -483,7 +483,7 @@ void TestQmllint::dirtyQmlCode_data()
     QTest::newRow("inheritanceCycle")
             << QStringLiteral("Cycle1.qml")
             << Result { { Message {
-                       QStringLiteral("Cycle2 is part of an inheritance cycle: Cycle2 -> Cycle3 "
+                       QStringLiteral("Cycle1 is part of an inheritance cycle: Cycle2 -> Cycle3 "
                                       "-> Cycle1 -> Cycle2"),
                        2, 1 } } };
     QTest::newRow("badQmldirImportAndDepend")

tests/auto/qml/qqmljsscope/tst_qqmljsscope.cpp

@@ -84,7 +84,8 @@ class tst_qqmljsscope : public QQmlDataTest
         logger.setFileName(url);
         logger.setCode(sourceCode);
         logger.setSilent(true);
-        QQmlJSImportVisitor visitor(&m_importer, &logger, dataDirectory());
+        QQmlJSScope::Ptr target = QQmlJSScope::create();
+        QQmlJSImportVisitor visitor(target, &m_importer, &logger, dataDirectory());
         QQmlJSTypeResolver typeResolver { &m_importer };
         typeResolver.init(&visitor, document.program);
         return visitor.result();

tools/qmltc/qmltcvisitor.cpp

@@ -64,7 +64,8 @@ static bool isOrUnderComponent(QQmlJSScope::ConstPtr type)
 
 QmltcVisitor::QmltcVisitor(QQmlJSImporter *importer, QQmlJSLogger *logger,
                            const QString &implicitImportDirectory, const QStringList &qmldirFiles)
-    : QQmlJSImportVisitor(importer, logger, implicitImportDirectory, qmldirFiles)
+    : QQmlJSImportVisitor(
+            QQmlJSScope::create(), importer, logger, implicitImportDirectory, qmldirFiles)
 {
     m_qmlTypeNames.append(QFileInfo(logger->fileName()).baseName()); // put document root
 }
@@ -267,7 +268,7 @@ bool QmltcVisitor::visit(QQmlJS::AST::UiInlineComponent *component)
 void QmltcVisitor::endVisit(QQmlJS::AST::UiProgram *program)
 {
     QQmlJSImportVisitor::endVisit(program);
-    if (!m_exportedRootScope) // in case we failed badly
+    if (!rootScopeIsValid()) // in case we failed badly
         return;
 
     QHash<QQmlJSScope::ConstPtr, QList<QQmlJSMetaPropertyBinding>> bindings;