error: invalid covariant return type for ‘virtual std::variant<QQmlJSAotFunction

qmlcompilerplus/src/qmlcompilerplus/cppcodegen.cpp
In file included from /home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/cppcodegen.cpp:4:
/home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/cppcodegen_p.h:45:64: error: invalid covariant return type for ‘virtual std::variant<QQmlJSAotFunction, QQmlJS::DiagnosticMessage> CppCodeGenerator::compileBinding(const QV4::Compiler::Context*, const QmlIR::Binding&, QQmlJS::AST::Node*)’
   45 |     std::variant<QQmlJSAotFunction, QQmlJS::DiagnosticMessage> compileBinding(
      |                                                                ^~~~~~~~~~~~~~
In file included from /home/qt/work/install/include/QtQmlCompiler/6.9.0/QtQmlCompiler/private/qqmljscodegenerator_p.h:17,
                 from /home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/bytecodetranslator_p.h:19,
                 from /home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/cppcodegen_p.h:17:
/home/qt/work/install/include/QtQmlCompiler/6.9.0/QtQmlCompiler/private/qqmljscompiler_p.h:73:79: note: overridden function is ‘virtual std::variant<QQmlJSAotFunction, QList<QQmlJS::DiagnosticMessage> > QQmlJSAotCompiler::compileBinding(const QV4::Compiler::Context*, const QmlIR::Binding&, QQmlJS::AST::Node*)’
   73 |     virtual std::variant<QQmlJSAotFunction, QList<QQmlJS::DiagnosticMessage>> compileBinding(
      |                                                                               ^~~~~~~~~~~~~~
/home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/cppcodegen_p.h:48:64: error: invalid covariant return type for ‘virtual std::variant<QQmlJSAotFunction, QQmlJS::DiagnosticMessage> CppCodeGenerator::compileFunction(const QV4::Compiler::Context*, const QString&, QQmlJS::AST::Node*)’
   48 |     std::variant<QQmlJSAotFunction, QQmlJS::DiagnosticMessage> compileFunction(
      |                                                                ^~~~~~~~~~~~~~~
/home/qt/work/install/include/QtQmlCompiler/6.9.0/QtQmlCompiler/private/qqmljscompiler_p.h:76:79: note: overridden function is ‘virtual std::variant<QQmlJSAotFunction, QList<QQmlJS::DiagnosticMessage> > QQmlJSAotCompiler::compileFunction(const QV4::Compiler::Context*, const QString&, QQmlJS::AST::Node*)’
   76 |     virtual std::variant<QQmlJSAotFunction, QList<QQmlJS::DiagnosticMessage>> compileFunction(
      |                                                                               ^~~~~~~~~~~~~~~
In file included from /home/qt/work/install/include/QtCore/qglobal.h:35,
                 from /home/qt/work/install/include/QtCore/6.9.0/QtCore/private/qglobal_p.h:19,
                 from /home/qt/work/install/include/QtQml/6.9.0/QtQml/private/qqmljssourcelocation_p.h:7,
                 from /home/qt/work/install/include/QtQml/6.9.0/QtQml/private/qqmljsastfwd_p.h:7,
                 from /home/qt/work/install/include/QtQml/6.9.0/QtQml/private/qqmljsastvisitor_p.h:18,
                 from /home/qt/work/install/include/QtQml/6.9.0/QtQml/private/qqmljsast_p.h:18,
                 from /home/qt/work/install/include/QtQmlCompiler/6.9.0/QtQmlCompiler/private/qqmljstypepropagator_p.h:17,
                 from /home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/bytecodetranslator_p.h:17:
/home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/cppcodegen.cpp: In lambda function:
/home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/cppcodegen.cpp:53:25: error: ‘struct QQmlJS::DiagnosticMessage’ has no member named ‘isValid’
   53 |         Q_ASSERT(error->isValid());
      |                         ^~~~~~~
/home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/cppcodegen.cpp: In member function ‘QQmlJSAotFunction CppCodeGenerator::doCompile(const QV4::Compiler::Context*, QQmlJSCompilePass::Function*, QQmlJS::DiagnosticMessage*)’:
/home/qt/work/qt/tqtc-qmlcompilerplus/src/qmlcompilerplus/cppcodegen.cpp:59:86: error: no matching function for call to ‘QQmlJSBasicBlocks::QQmlJSBasicBlocks(const QV4::Compiler::Context*&, const QV4::Compiler::JSUnitGenerator*&, QQmlJSTypeResolver*, QQmlJSLogger*&)’
   59 |     QQmlJSBasicBlocks basicBlocks(context, m_unitGenerator, &m_typeResolver, m_logger);
      |                      
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