remove c++17 requirements

src/mvvmcore/qtmvvmcore_helpertypes.h

@@ -12,14 +12,6 @@
 namespace QtMvvm {
 namespace __helpertypes {
 
-#if __cplusplus >= 201703L
-template<typename... T>
-using conjunction = std::conjunction<T...>;
-#else
-template<typename... T>
-using conjunction = std::__and_<T...>;
-#endif
-
 static const QByteArray InjectablePrefix = QByteArrayLiteral("de.skycoder42.qtmvvm.injectable.");
 
 template <typename T>
@@ -29,7 +21,7 @@ template <typename T>
 struct is_qobj_ptr : public is_qobj<std::remove_pointer_t<T>> {};
 
 template <typename TInterface, typename TService>
-struct is_valid_interface : public conjunction<std::is_base_of<TInterface, TService>, is_qobj<TService>> {};
+struct is_valid_interface : public std::integral_constant<bool, std::is_base_of<TInterface, TService>::value && is_qobj<TService>::value> {};
 
 template <typename TInjectPtr>
 inline QByteArray qobject_iid(std::enable_if_t<is_qobj_ptr<TInjectPtr>::value, void*> = nullptr) {
@@ -52,7 +44,7 @@ inline QByteArray inject_iid() {
 }
 
 template <typename TFunc, typename T1, typename... TArgs>
-inline Q_CONSTEXPR std::function<QObject*(QObjectList)> pack_function_imp(const TFunc &fn, QByteArrayList &injectables) {
+inline std::function<QObject*(QObjectList)> pack_function_imp(const TFunc &fn, QByteArrayList &injectables) {
 	injectables.append(inject_iid<T1>());
 	auto subFn = [fn](const QObjectList &params, int index, TArgs... tArgs) {
 		--index;
@@ -62,7 +54,7 @@ inline Q_CONSTEXPR std::function<QObject*(QObjectList)> pack_function_imp(const
 }
 
 template <typename TFunc>
-inline Q_CONSTEXPR std::function<QObject*(QObjectList)> pack_function_imp(const TFunc &fn, QByteArrayList &injectables) {
+inline std::function<QObject*(QObjectList)> pack_function_imp(const TFunc &fn, QByteArrayList &injectables) {
 	Q_UNUSED(injectables)
 	return [fn](const QObjectList &params) {
 		return fn(params, params.size());
@@ -76,7 +68,7 @@ template <typename TClass, typename TRet, typename... TArgs>
 struct fn_info<TRet(TClass::*)(TArgs...) const>
 {
 	template <typename TFunctor>
-	static inline Q_CONSTEXPR std::function<QObject*(QObjectList)> pack(const TFunctor &fn, QByteArrayList &injectables) {
+	static inline std::function<QObject*(QObjectList)> pack(const TFunctor &fn, QByteArrayList &injectables) {
 		auto subFn = [fn](const QObjectList &params, int index, TArgs... args) -> QObject* {
 			Q_UNUSED(params)
 			Q_ASSERT_X(index == 0, Q_FUNC_INFO, "number of params does not equal recursion depth");
@@ -87,7 +79,7 @@ struct fn_info<TRet(TClass::*)(TArgs...) const>
 };
 
 template <typename TFunc>
-inline Q_CONSTEXPR std::function<QObject*(QObjectList)> pack_function(const TFunc &fn, QByteArrayList &injectables) {
+inline std::function<QObject*(QObjectList)> pack_function(const TFunc &fn, QByteArrayList &injectables) {
 	return fn_info<TFunc>::pack(fn, injectables);
 }