diff --git a/include/nlohmann/detail/meta/type_traits.hpp b/include/nlohmann/detail/meta/type_traits.hpp index e30d99e4c..1fbf7cde7 100644 --- a/include/nlohmann/detail/meta/type_traits.hpp +++ b/include/nlohmann/detail/meta/type_traits.hpp @@ -149,6 +149,52 @@ struct has_to_json < BasicJsonType, T, enable_if_t < !is_basic_json::value >> /////////////////// // is_ functions // /////////////////// +// https://en.cppreference.com/w/cpp/types/conjunction +template struct conjunction : std::true_type { }; +template struct conjunction : B1 { }; +template +struct conjunction +: std::conditional, B1>::type {}; + +// Reimplementation of is_constructible and is_default_constructible, due to them being broken for +// std::pair and std::tuple until LWG 2367 fix (see https://cplusplus.github.io/LWG/lwg-defects.html#2367). +// This causes compile errors in e.g. clang 3.5 or gcc 4.9. +// Based on commit fixing this in gcc: https://github.com/gcc-mirror/gcc/commit/d3c64041b32b6962ad6b2d879231537a477631fb +template +struct is_default_constructible : std::is_default_constructible {}; + +template +struct is_default_constructible> + : conjunction, is_default_constructible> {}; + +template +struct is_default_constructible> + : conjunction, is_default_constructible> {}; + +template +struct is_default_constructible> + : conjunction...> {}; + +template +struct is_default_constructible> + : conjunction...> {}; + + +template +struct is_constructible : std::is_constructible {}; + +template +struct is_constructible> : is_default_constructible> {}; + +template +struct is_constructible> : is_default_constructible> {}; + +template +struct is_constructible> : is_default_constructible> {}; + +template +struct is_constructible> : is_default_constructible> {}; + template struct is_iterator_traits : std::false_type {}; @@ -192,9 +238,9 @@ struct is_compatible_object_type_impl < // macOS's is_constructible does not play well with nonesuch... static constexpr bool value = - std::is_constructible::value && - std::is_constructible::value; }; @@ -215,10 +261,10 @@ struct is_constructible_object_type_impl < using object_t = typename BasicJsonType::object_t; static constexpr bool value = - (std::is_default_constructible::value && + (is_default_constructible::value && (std::is_move_assignable::value || std::is_copy_assignable::value) && - (std::is_constructible::value && std::is_same < typename object_t::mapped_type, @@ -246,7 +292,7 @@ struct is_compatible_string_type_impl < value_type_t, CompatibleStringType>::value >> { static constexpr auto value = - std::is_constructible::value; + is_constructible::value; }; template @@ -264,7 +310,7 @@ struct is_constructible_string_type_impl < value_type_t, ConstructibleStringType>::value >> { static constexpr auto value = - std::is_constructible::value; }; @@ -287,7 +333,7 @@ struct is_compatible_array_type_impl < iterator_traits>::value >> { static constexpr bool value = - std::is_constructible::value; }; @@ -310,7 +356,7 @@ struct is_constructible_array_type_impl < BasicJsonType, ConstructibleArrayType, enable_if_t < !std::is_same::value&& - std::is_default_constructible::value&& + is_default_constructible::value&& (std::is_move_assignable::value || std::is_copy_assignable::value)&& is_detected::value&& @@ -354,7 +400,7 @@ struct is_compatible_integer_type_impl < using CompatibleLimits = std::numeric_limits; static constexpr auto value = - std::is_constructible::value && CompatibleLimits::is_integer && RealLimits::is_signed == CompatibleLimits::is_signed; @@ -381,17 +427,10 @@ template struct is_compatible_type : is_compatible_type_impl {}; -// https://en.cppreference.com/w/cpp/types/conjunction -template struct conjunction : std::true_type { }; -template struct conjunction : B1 { }; -template -struct conjunction -: std::conditional, B1>::type {}; - template struct is_constructible_tuple : std::false_type {}; template -struct is_constructible_tuple> : conjunction...> {}; +struct is_constructible_tuple> : conjunction...> {}; } // namespace detail } // namespace nlohmann