diff options
Diffstat (limited to 'src/corelib/global/q20type_traits.h')
| -rw-r--r-- | src/corelib/global/q20type_traits.h | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/src/corelib/global/q20type_traits.h b/src/corelib/global/q20type_traits.h index 2e812ed39c..63a453daca 100644 --- a/src/corelib/global/q20type_traits.h +++ b/src/corelib/global/q20type_traits.h @@ -3,6 +3,8 @@ #ifndef Q20TYPE_TRAITS_H #define Q20TYPE_TRAITS_H +#include <QtCore/qcompilerdetection.h> +#include <QtCore/qsystemdetection.h> #include <QtCore/qtconfigmacros.h> // @@ -26,6 +28,29 @@ QT_BEGIN_NAMESPACE namespace q20 { +// like std::is_constant_evaluated +#ifdef __cpp_lib_is_constant_evaluated +using std::is_constant_evaluated; +#define QT_SUPPORTS_IS_CONSTANT_EVALUATED +#else +constexpr bool is_constant_evaluated() noexcept +{ +#ifdef Q_OS_INTEGRITY + // Integrity complains "calling __has_builtin() from a constant expression". + // Avoid the __has_builtin check until we know what's going on. + return false; +#elif __has_builtin(__builtin_is_constant_evaluated) || \ + (defined(Q_CC_MSVC_ONLY) /* >= 1925, but we require 1927 in qglobal.h */) +# define QT_SUPPORTS_IS_CONSTANT_EVALUATED + return __builtin_is_constant_evaluated(); +#else + return false; +#endif +} +#endif // __cpp_lib_is_constant_evaluated +} + +namespace q20 { // like std::remove_cvref(_t) #ifdef __cpp_lib_remove_cvref using std::remove_cvref; @@ -38,6 +63,19 @@ using remove_cvref_t = std::remove_cv_t<std::remove_reference_t<T>>; #endif // __cpp_lib_remove_cvref } +namespace q20 { +// like std::type_identity(_t) +#ifdef __cpp_lib_type_identity +using std::type_identity; +using std::type_identity_t; +#else +template <typename T> +struct type_identity { using type = T; }; +template <typename T> +using type_identity_t = typename type_identity<T>::type; +#endif // __cpp_lib_type_identity +} + QT_END_NAMESPACE #endif /* Q20TYPE_TRAITS_H */ |