qtypeinfo: make variable templates inline

And refactor the TMP to use std::conjunction and use variable template
specialization instead of template class specialization for the base
cases.

Change-Id: Iea6a03f13ea3443a0fa7365af21c496670c1e07f
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 19 insertions, 14 deletions

diff --git a/src/corelib/global/qtypeinfo.h b/src/corelib/global/qtypeinfo.h
index e5914414f2..fea6ecd45c 100644
--- a/src/corelib/global/qtypeinfo.h
+++ b/src/corelib/global/qtypeinfo.h
@@ -311,14 +311,13 @@ struct expand_operator_less_than_tuple<std::variant<T...>> : expand_operator_les
 }
 
 template<typename T, typename = void>
-struct is_dereferenceable : std::false_type {};
+inline constexpr bool is_dereferenceable_v = false;
 
 template<typename T>
-struct is_dereferenceable<T, std::void_t<decltype(std::declval<T>().operator->())> >
-    : std::true_type {};
+inline constexpr bool is_dereferenceable_v<T, std::void_t<decltype(std::declval<T>().operator->())> > = true;
 
 template <typename T>
-inline constexpr bool is_dereferenceable_v = is_dereferenceable<T>::value;
+using is_dereferenceable = std::bool_constant<is_dereferenceable_v<T>>;
 
 template<typename T>
 struct has_operator_equal : detail::expand_operator_equal<T> {};
@@ -345,25 +344,31 @@ T &reference();
 
 }
 
-template <typename Stream, typename, typename = void>
-struct has_ostream_operator : std::false_type {};
+template <typename Stream, typename T, typename = void>
+inline constexpr bool has_ostream_operator_v = false;
+
 template <typename Stream, typename T>
-struct has_ostream_operator<Stream, T, std::void_t<decltype(detail::reference<Stream>() << detail::const_reference<T>())>>
-        : std::true_type {};
+inline constexpr bool has_ostream_operator_v<Stream, T, std::void_t<decltype(detail::reference<Stream>() << detail::const_reference<T>())>> = true;
+
 template <typename Stream, typename T>
-inline constexpr bool has_ostream_operator_v = has_ostream_operator<Stream, T>::value;
+using has_ostream_operator = std::bool_constant<has_ostream_operator_v<Stream, T>>;
+
+
+
+template <typename Stream, typename T, typename = void>
+inline constexpr bool has_istream_operator_v = false;
 
-template <typename Stream, typename, typename = void>
-struct has_istream_operator : std::false_type {};
 template <typename Stream, typename T>
-struct has_istream_operator<Stream, T, std::void_t<decltype(detail::reference<Stream>() >> detail::reference<T>())>>
-        : std::true_type {};
+inline constexpr bool has_istream_operator_v<Stream, T, std::void_t<decltype(detail::reference<Stream>() >> detail::reference<T>())>> = true;
+
 template <typename Stream, typename T>
-inline constexpr bool has_istream_operator_v = has_istream_operator<Stream, T>::value;
+using has_istream_operator = std::bool_constant<has_istream_operator_v<Stream, T>>;
 
 template <typename Stream, typename T>
 inline constexpr bool has_stream_operator_v = has_ostream_operator_v<Stream, T> && has_istream_operator_v<Stream, T>;
 
+template <typename Stream, typename T>
+using has_stream_operator = std::conjunction<has_ostream_operator<Stream, T>, has_istream_operator<Stream, T>>;
 }