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diff --git a/include/meta/meta_fwd.hpp b/include/meta/meta_fwd.hpp
index edfb9068..ac041999 100644
--- a/include/meta/meta_fwd.hpp
+++ b/include/meta/meta_fwd.hpp
@@ -152,6 +152,13 @@
#define META_TYPE_CONSTRAINT(...) typename
#endif
+#if (defined(__cpp_lib_type_trait_variable_templates) && \
+ __cpp_lib_type_trait_variable_templates > 0)
+#define META_CXX_TRAIT_VARIABLE_TEMPLATES 1
+#else
+#define META_CXX_TRAIT_VARIABLE_TEMPLATES 0
+#endif
+
namespace meta
{
#if META_CXX_INTEGER_SEQUENCE
@@ -208,8 +215,10 @@ namespace meta
META_CONCEPT_BARRIER(__is_same(T, U));
#elif defined(__GNUC__) && __GNUC__ >= 6
META_CONCEPT_BARRIER(__is_same_as(T, U));
-#else
+#elif defined(META_CXX_TRAIT_VARIABLE_TEMPLATES)
META_CONCEPT_BARRIER(std::is_same_v<T, U>);
+#else
+ META_CONCEPT_BARRIER(std::is_same<T, U>::value);
#endif
template <template <typename...> class C, typename... Ts>
@@ -248,7 +257,11 @@ namespace meta
typename T::type::value_type;
}
&& Same<typename T::value_type, typename T::type::value_type>
+#if META_CXX_TRAIT_VARIABLE_TEMPLATES
&& std::is_integral_v<typename T::value_type>
+#else
+ && std::is_integral<typename T::value_type>::value
+#endif
&& requires
{
// { T::value } -> Same<const typename T::value_type&>;
diff --git a/include/range/v3/range_fwd.hpp b/include/range/v3/range_fwd.hpp
index 0378a0bd..2fabf26c 100644
--- a/include/range/v3/range_fwd.hpp
+++ b/include/range/v3/range_fwd.hpp
@@ -247,6 +247,16 @@ namespace ranges
struct priority_tag<0>
{};
+ template<typename T>
+ using is_trivial = meta::bool_<
+#if META_CXX_TRAIT_VARIABLE_TEMPLATES
+ std::is_trivially_copyable_v<T> &&
+ std::is_trivially_default_constructible_v<T>>;
+#else
+ std::is_trivially_copyable<T>::value &&
+ std::is_trivially_default_constructible<T>::value>;
+#endif
+
#if defined(__clang__) && !defined(_LIBCPP_VERSION)
template<typename T, typename... Args>
using is_trivially_constructible =
@@ -272,19 +282,6 @@ namespace ranges
template<typename T>
using is_trivially_copyable =
meta::bool_<__is_trivially_copyable(T)>;
- #elif defined(__GNUC__) && !defined(__clang__) && __GNUC__ < 5
- template<typename T>
- using is_trivially_default_constructible = std::is_trivial<T>;
- template<typename T>
- using is_trivially_copy_constructible = std::is_trivial<T>;
- template<typename T>
- using is_trivially_move_constructible = std::is_trivial<T>;
- template<typename T>
- using is_trivially_copy_assignable = std::is_trivial<T>;
- template<typename T>
- using is_trivially_move_assignable = std::is_trivial<T>;
- template<typename T>
- using is_trivially_copyable = std::is_trivial<T>;
#else
template<typename T>
using is_trivially_default_constructible =
diff --git a/include/range/v3/utility/box.hpp b/include/range/v3/utility/box.hpp
index 5e8b90dd..33d674df 100644
--- a/include/range/v3/utility/box.hpp
+++ b/include/range/v3/utility/box.hpp
@@ -128,7 +128,7 @@ namespace ranges
// MSVC pukes passing non-constant-expression objects to constexpr
// functions, so do not coalesce.
template<typename T, typename = meta::if_<
- meta::strict_and<std::is_empty<T>, std::is_trivial<T>>>>
+ meta::strict_and<std::is_empty<T>, detail::is_trivial<T>>>>
constexpr box_compress box_compression_(int)
{
return box_compress::coalesce;
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