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Add internal version of is_default_constructible to work around LWG 2367.
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Anthony VH
parent
672e8bfc1d
commit
6ebf274ca0
@ -149,6 +149,52 @@ struct has_to_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
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///////////////////
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// is_ functions //
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///////////////////
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// https://en.cppreference.com/w/cpp/types/conjunction
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template<class...> struct conjunction : std::true_type { };
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template<class B1> struct conjunction<B1> : B1 { };
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template<class B1, class... Bn>
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struct conjunction<B1, Bn...>
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: std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
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// Reimplementation of is_constructible and is_default_constructible, due to them being broken for
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// std::pair and std::tuple until LWG 2367 fix (see https://cplusplus.github.io/LWG/lwg-defects.html#2367).
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// This causes compile errors in e.g. clang 3.5 or gcc 4.9.
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// Based on commit fixing this in gcc: https://github.com/gcc-mirror/gcc/commit/d3c64041b32b6962ad6b2d879231537a477631fb
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template <typename T>
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struct is_default_constructible : std::is_default_constructible<T> {};
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template <typename T1, typename T2>
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struct is_default_constructible<std::pair<T1, T2>>
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: conjunction<is_default_constructible<T1>, is_default_constructible<T2>> {};
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template <typename T1, typename T2>
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struct is_default_constructible<const std::pair<T1, T2>>
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: conjunction<is_default_constructible<T1>, is_default_constructible<T2>> {};
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template <typename... Ts>
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struct is_default_constructible<std::tuple<Ts...>>
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: conjunction<is_default_constructible<Ts>...> {};
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template <typename... Ts>
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struct is_default_constructible<const std::tuple<Ts...>>
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: conjunction<is_default_constructible<Ts>...> {};
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template <typename T, typename... Args>
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struct is_constructible : std::is_constructible<T, Args...> {};
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template <typename T1, typename T2>
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struct is_constructible<std::pair<T1, T2>> : is_default_constructible<std::pair<T1, T2>> {};
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template <typename T1, typename T2>
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struct is_constructible<const std::pair<T1, T2>> : is_default_constructible<const std::pair<T1, T2>> {};
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template <typename... Ts>
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struct is_constructible<std::tuple<Ts...>> : is_default_constructible<std::tuple<Ts...>> {};
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template <typename... Ts>
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struct is_constructible<const std::tuple<Ts...>> : is_default_constructible<const std::tuple<Ts...>> {};
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template<typename T, typename = void>
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struct is_iterator_traits : std::false_type {};
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@ -192,9 +238,9 @@ struct is_compatible_object_type_impl <
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// macOS's is_constructible does not play well with nonesuch...
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static constexpr bool value =
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std::is_constructible<typename object_t::key_type,
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is_constructible<typename object_t::key_type,
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typename CompatibleObjectType::key_type>::value &&
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std::is_constructible<typename object_t::mapped_type,
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is_constructible<typename object_t::mapped_type,
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typename CompatibleObjectType::mapped_type>::value;
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};
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@ -215,10 +261,10 @@ struct is_constructible_object_type_impl <
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using object_t = typename BasicJsonType::object_t;
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static constexpr bool value =
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(std::is_default_constructible<ConstructibleObjectType>::value &&
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(is_default_constructible<ConstructibleObjectType>::value &&
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(std::is_move_assignable<ConstructibleObjectType>::value ||
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std::is_copy_assignable<ConstructibleObjectType>::value) &&
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(std::is_constructible<typename ConstructibleObjectType::key_type,
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(is_constructible<typename ConstructibleObjectType::key_type,
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typename object_t::key_type>::value &&
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std::is_same <
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typename object_t::mapped_type,
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@ -246,7 +292,7 @@ struct is_compatible_string_type_impl <
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value_type_t, CompatibleStringType>::value >>
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{
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static constexpr auto value =
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std::is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
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is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
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};
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template<typename BasicJsonType, typename ConstructibleStringType>
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@ -264,7 +310,7 @@ struct is_constructible_string_type_impl <
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value_type_t, ConstructibleStringType>::value >>
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{
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static constexpr auto value =
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std::is_constructible<ConstructibleStringType,
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is_constructible<ConstructibleStringType,
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typename BasicJsonType::string_t>::value;
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};
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@ -287,7 +333,7 @@ struct is_compatible_array_type_impl <
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iterator_traits<CompatibleArrayType >>::value >>
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{
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static constexpr bool value =
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std::is_constructible<BasicJsonType,
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is_constructible<BasicJsonType,
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typename CompatibleArrayType::value_type>::value;
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};
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@ -310,7 +356,7 @@ struct is_constructible_array_type_impl <
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BasicJsonType, ConstructibleArrayType,
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enable_if_t < !std::is_same<ConstructibleArrayType,
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typename BasicJsonType::value_type>::value&&
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std::is_default_constructible<ConstructibleArrayType>::value&&
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is_default_constructible<ConstructibleArrayType>::value&&
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(std::is_move_assignable<ConstructibleArrayType>::value ||
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std::is_copy_assignable<ConstructibleArrayType>::value)&&
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is_detected<value_type_t, ConstructibleArrayType>::value&&
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@ -354,7 +400,7 @@ struct is_compatible_integer_type_impl <
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using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
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static constexpr auto value =
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std::is_constructible<RealIntegerType,
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is_constructible<RealIntegerType,
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CompatibleNumberIntegerType>::value &&
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CompatibleLimits::is_integer &&
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RealLimits::is_signed == CompatibleLimits::is_signed;
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@ -381,17 +427,10 @@ template<typename BasicJsonType, typename CompatibleType>
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struct is_compatible_type
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: is_compatible_type_impl<BasicJsonType, CompatibleType> {};
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// https://en.cppreference.com/w/cpp/types/conjunction
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template<class...> struct conjunction : std::true_type { };
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template<class B1> struct conjunction<B1> : B1 { };
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template<class B1, class... Bn>
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struct conjunction<B1, Bn...>
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: std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
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template<typename T1, typename T2>
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struct is_constructible_tuple : std::false_type {};
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template<typename T1, typename... Args>
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struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<std::is_constructible<T1, Args>...> {};
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struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<is_constructible<T1, Args>...> {};
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} // namespace detail
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} // namespace nlohmann
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