Merge 140943b18e into 307c053b9b

include/nlohmann/detail/conversions/to_json.hpp

@@ -221,6 +221,16 @@ struct external_constructor<value_t::array>
 template<>
 struct external_constructor<value_t::object>
 {
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j)
+    {
+        j.m_value.destroy(j.m_type);
+        j.m_type = value_t::object;
+        j.m_value.object = j.template create<typename BasicJsonType::object_t>();
+        j.set_parents();
+        j.assert_invariant();
+    }
+
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::object_t& obj)
     {
@@ -256,6 +266,28 @@ struct external_constructor<value_t::object>
     }
 };
 
+//////////////
+// wrappers //
+//////////////
+
+template<typename ArrayType>
+struct array_type_wrapper
+{
+    const ArrayType& array;
+};
+
+template<typename ObjectType>
+struct object_type_wrapper
+{
+    const ObjectType& object;
+};
+
+template<typename StringType>
+struct string_type_wrapper
+{
+    const StringType& string;
+};
+
 /////////////
 // to_json //
 /////////////
@@ -293,6 +325,17 @@ inline void to_json(BasicJsonType& j, typename BasicJsonType::string_t&& s)
     external_constructor<value_t::string>::construct(j, std::move(s));
 }
 
+template<typename BasicJsonType, typename StringType>
+using string_type_constructible_from_data_and_size = decltype(typename BasicJsonType::string_t(
+            std::declval<const StringType&>().data(), std::declval<const StringType&>().size()));
+
+template<typename BasicJsonType, typename StringType, detail::enable_if_t<
+             detail::is_detected<string_type_constructible_from_data_and_size, BasicJsonType, StringType>::value, int> = 0>
+void to_json(BasicJsonType& j, detail::string_type_wrapper<StringType> s)
+{
+    external_constructor<value_t::string>::construct(j, typename BasicJsonType::string_t(s.string.data(), s.string.size()));
+}
+
 template<typename BasicJsonType, typename FloatType,
          enable_if_t<std::is_floating_point<FloatType>::value, int> = 0>
 inline void to_json(BasicJsonType& j, FloatType val) noexcept
@@ -343,6 +386,18 @@ inline void to_json(BasicJsonType& j, const CompatibleArrayType& arr)
     external_constructor<value_t::array>::construct(j, arr);
 }
 
+template<typename BasicJsonType, typename ArrayType>
+using array_type_constructible_from_iter = decltype(typename BasicJsonType::array_t(
+            std::declval<result_of_begin<const ArrayType&>>(), std::declval<result_of_end<const ArrayType&>>()));
+
+template<typename BasicJsonType, typename ArrayType, detail::enable_if_t<
+             detail::is_detected<array_type_constructible_from_iter, BasicJsonType, ArrayType>::value, int> = 0>
+void to_json(BasicJsonType& j, detail::array_type_wrapper<ArrayType> a)
+{
+    external_constructor<value_t::array>::construct(j,
+            typename BasicJsonType::array_t(a.array.begin(), a.array.end()));
+}
+
 template<typename BasicJsonType>
 inline void to_json(BasicJsonType& j, const typename BasicJsonType::binary_t& bin)
 {
@@ -375,6 +430,43 @@ inline void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
     external_constructor<value_t::object>::construct(j, std::move(obj));
 }
 
+template < typename BasicJsonType, typename ObjectType,
+           enable_if_t < is_compatible_object_type<BasicJsonType, ObjectType>::value
+                         || is_basic_json<ObjectType>::value, int > = 0 >
+void to_json(BasicJsonType& j, const object_type_wrapper<ObjectType>& obj)
+{
+    external_constructor<value_t::object>::construct(j, obj.object);
+}
+
+template<typename BasicJsonType, typename ObjectType>
+using object_type_key_constructible_from_data_and_size = decltype(
+            typename BasicJsonType::object_t::key_type(
+                std::declval<const typename ObjectType::key_type&>().data(),
+                std::declval<const typename ObjectType::key_type&>().size()));
+
+template < typename BasicJsonType, typename ObjectType,
+           enable_if_t < !is_compatible_object_type<BasicJsonType, ObjectType>::value
+                         && !is_basic_json<ObjectType>::value
+                         && detail::is_detected<object_type_key_constructible_from_data_and_size,
+                                 BasicJsonType, ObjectType>::value, int > = 0 >
+void to_json(BasicJsonType& j, const object_type_wrapper<ObjectType>& o)
+{
+    using std::begin;
+    using std::end;
+
+    external_constructor<value_t::object>::construct(j);
+
+    auto& obj = j.template get_ref<typename BasicJsonType::object_t&>();
+    std::transform(begin(o.object), end(o.object), std::inserter(obj, obj.end()),
+                   [](const typename ObjectType::value_type & val)
+    {
+        return typename BasicJsonType::object_t::value_type
+        {
+            typename BasicJsonType::object_t::key_type(val.first.data(), val.first.size()),
+            BasicJsonType(val.second)};
+    });
+}
+
 template <
     typename BasicJsonType, typename T, std::size_t N,
     enable_if_t < !std::is_constructible<typename BasicJsonType::string_t,

include/nlohmann/json.hpp

@@ -833,12 +833,79 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         assert_invariant();
     }
 
+  private:
+    template<typename BasicJsonType, class Serializer, typename SerializedType,
+             class WrapperType>
+    using serializer_has_to_json_with_type_wrapper = decltype(Serializer::to_json(
+                std::declval<BasicJsonType&>(), std::declval<const WrapperType&>()));
+
+    template <typename OtherStringType,
+              detail::enable_if_t <
+                  detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                      basic_json_t, JSONSerializer<OtherStringType>, OtherStringType,
+                                      detail::string_type_wrapper<OtherStringType>>::value, int > = 0 >
+    void other_string_to_json(const OtherStringType& str)
+    {
+        JSONSerializer<OtherStringType>::to_json(*this, detail::string_type_wrapper<OtherStringType> {str});
+    }
+
+    template < typename OtherStringType,
+               detail::enable_if_t <
+                   !detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                        basic_json_t, JSONSerializer<OtherStringType>, OtherStringType,
+                                        detail::string_type_wrapper<OtherStringType>>::value, int > = 0 >
+    void other_string_to_json(const OtherStringType& str)
+    {
+        JSONSerializer<OtherStringType>::to_json(*this, str);
+    }
+
+    template <typename OtherObjectType,
+              detail::enable_if_t <
+                  detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                      basic_json_t, JSONSerializer<OtherObjectType>, OtherObjectType,
+                                      detail::object_type_wrapper<OtherObjectType>>::value, int > = 0 >
+    void other_object_to_json(const OtherObjectType& obj)
+    {
+        JSONSerializer<OtherObjectType>::to_json(*this, detail::object_type_wrapper<OtherObjectType> {obj});
+    }
+
+    template < typename OtherObjectType,
+               detail::enable_if_t <
+                   !detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                        basic_json_t, JSONSerializer<OtherObjectType>, OtherObjectType,
+                                        detail::object_type_wrapper<OtherObjectType>>::value, int > = 0 >
+    void other_object_to_json(const OtherObjectType& obj)
+    {
+        JSONSerializer<OtherObjectType>::to_json(*this, obj);
+    }
+
+    template <typename OtherArrayType,
+              detail::enable_if_t <
+                  detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                      basic_json_t, JSONSerializer<OtherArrayType>, OtherArrayType,
+                                      detail::array_type_wrapper<OtherArrayType>>::value, int > = 0 >
+    void other_array_to_json(const OtherArrayType& arr)
+    {
+        JSONSerializer<OtherArrayType>::to_json(*this, detail::array_type_wrapper<OtherArrayType> {arr});
+    }
+
+    template < typename OtherArrayType,
+               detail::enable_if_t <
+                   !detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                        basic_json_t, JSONSerializer<OtherArrayType>, OtherArrayType,
+                                        detail::array_type_wrapper<OtherArrayType>>::value, int > = 0 >
+    void other_array_to_json(const OtherArrayType& arr)
+    {
+        JSONSerializer<OtherArrayType>::to_json(*this, arr);
+    }
+
+  public:
     /// @brief create a JSON value from an existing one
     /// @sa https://json.nlohmann.me/api/basic_json/basic_json/
     template < typename BasicJsonType,
                detail::enable_if_t <
                    detail::is_basic_json<BasicJsonType>::value&& !std::is_same<basic_json, BasicJsonType>::value, int > = 0 >
-    basic_json(const BasicJsonType& val)
+    JSON_EXPLICIT basic_json(const BasicJsonType& val)
     {
         using other_boolean_t = typename BasicJsonType::boolean_t;
         using other_number_float_t = typename BasicJsonType::number_float_t;
@@ -864,13 +931,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                 JSONSerializer<other_number_unsigned_t>::to_json(*this, val.template get<other_number_unsigned_t>());
                 break;
             case value_t::string:
-                JSONSerializer<other_string_t>::to_json(*this, val.template get_ref<const other_string_t&>());
+                other_string_to_json(val.template get_ref<const other_string_t&>());
                 break;
             case value_t::object:
-                JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
+                other_object_to_json(val.template get_ref<const other_object_t&>());
                 break;
             case value_t::array:
-                JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
+                other_array_to_json(val.template get_ref<const other_array_t&>());
                 break;
             case value_t::binary:
                 JSONSerializer<other_binary_t>::to_json(*this, val.template get_ref<const other_binary_t&>());
@@ -1665,7 +1732,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                    int > = 0 >
     BasicJsonType get_impl(detail::priority_tag<2> /*unused*/) const
     {
-        return *this;
+        return BasicJsonType(*this);
     }
 
     /*!

single_include/nlohmann/json.hpp

@@ -5531,6 +5531,16 @@ struct external_constructor<value_t::array>
 template<>
 struct external_constructor<value_t::object>
 {
+    template<typename BasicJsonType>
+    static void construct(BasicJsonType& j)
+    {
+        j.m_value.destroy(j.m_type);
+        j.m_type = value_t::object;
+        j.m_value.object = j.template create<typename BasicJsonType::object_t>();
+        j.set_parents();
+        j.assert_invariant();
+    }
+
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::object_t& obj)
     {
@@ -5566,6 +5576,28 @@ struct external_constructor<value_t::object>
     }
 };
 
+//////////////
+// wrappers //
+//////////////
+
+template<typename ArrayType>
+struct array_type_wrapper
+{
+    const ArrayType& array;
+};
+
+template<typename ObjectType>
+struct object_type_wrapper
+{
+    const ObjectType& object;
+};
+
+template<typename StringType>
+struct string_type_wrapper
+{
+    const StringType& string;
+};
+
 /////////////
 // to_json //
 /////////////
@@ -5603,6 +5635,17 @@ inline void to_json(BasicJsonType& j, typename BasicJsonType::string_t&& s)
     external_constructor<value_t::string>::construct(j, std::move(s));
 }
 
+template<typename BasicJsonType, typename StringType>
+using string_type_constructible_from_data_and_size = decltype(typename BasicJsonType::string_t(
+            std::declval<const StringType&>().data(), std::declval<const StringType&>().size()));
+
+template<typename BasicJsonType, typename StringType, detail::enable_if_t<
+             detail::is_detected<string_type_constructible_from_data_and_size, BasicJsonType, StringType>::value, int> = 0>
+void to_json(BasicJsonType& j, detail::string_type_wrapper<StringType> s)
+{
+    external_constructor<value_t::string>::construct(j, typename BasicJsonType::string_t(s.string.data(), s.string.size()));
+}
+
 template<typename BasicJsonType, typename FloatType,
          enable_if_t<std::is_floating_point<FloatType>::value, int> = 0>
 inline void to_json(BasicJsonType& j, FloatType val) noexcept
@@ -5653,6 +5696,18 @@ inline void to_json(BasicJsonType& j, const CompatibleArrayType& arr)
     external_constructor<value_t::array>::construct(j, arr);
 }
 
+template<typename BasicJsonType, typename ArrayType>
+using array_type_constructible_from_iter = decltype(typename BasicJsonType::array_t(
+            std::declval<result_of_begin<const ArrayType&>>(), std::declval<result_of_end<const ArrayType&>>()));
+
+template<typename BasicJsonType, typename ArrayType, detail::enable_if_t<
+             detail::is_detected<array_type_constructible_from_iter, BasicJsonType, ArrayType>::value, int> = 0>
+void to_json(BasicJsonType& j, detail::array_type_wrapper<ArrayType> a)
+{
+    external_constructor<value_t::array>::construct(j,
+            typename BasicJsonType::array_t(a.array.begin(), a.array.end()));
+}
+
 template<typename BasicJsonType>
 inline void to_json(BasicJsonType& j, const typename BasicJsonType::binary_t& bin)
 {
@@ -5685,6 +5740,43 @@ inline void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
     external_constructor<value_t::object>::construct(j, std::move(obj));
 }
 
+template < typename BasicJsonType, typename ObjectType,
+           enable_if_t < is_compatible_object_type<BasicJsonType, ObjectType>::value
+                         || is_basic_json<ObjectType>::value, int > = 0 >
+void to_json(BasicJsonType& j, const object_type_wrapper<ObjectType>& obj)
+{
+    external_constructor<value_t::object>::construct(j, obj.object);
+}
+
+template<typename BasicJsonType, typename ObjectType>
+using object_type_key_constructible_from_data_and_size = decltype(
+            typename BasicJsonType::object_t::key_type(
+                std::declval<const typename ObjectType::key_type&>().data(),
+                std::declval<const typename ObjectType::key_type&>().size()));
+
+template < typename BasicJsonType, typename ObjectType,
+           enable_if_t < !is_compatible_object_type<BasicJsonType, ObjectType>::value
+                         && !is_basic_json<ObjectType>::value
+                         && detail::is_detected<object_type_key_constructible_from_data_and_size,
+                                 BasicJsonType, ObjectType>::value, int > = 0 >
+void to_json(BasicJsonType& j, const object_type_wrapper<ObjectType>& o)
+{
+    using std::begin;
+    using std::end;
+
+    external_constructor<value_t::object>::construct(j);
+
+    auto& obj = j.template get_ref<typename BasicJsonType::object_t&>();
+    std::transform(begin(o.object), end(o.object), std::inserter(obj, obj.end()),
+                   [](const typename ObjectType::value_type & val)
+    {
+        return typename BasicJsonType::object_t::value_type
+        {
+            typename BasicJsonType::object_t::key_type(val.first.data(), val.first.size()),
+            BasicJsonType(val.second)};
+    });
+}
+
 template <
     typename BasicJsonType, typename T, std::size_t N,
     enable_if_t < !std::is_constructible<typename BasicJsonType::string_t,
@@ -20049,12 +20141,79 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         assert_invariant();
     }
 
+  private:
+    template<typename BasicJsonType, class Serializer, typename SerializedType,
+             class WrapperType>
+    using serializer_has_to_json_with_type_wrapper = decltype(Serializer::to_json(
+                std::declval<BasicJsonType&>(), std::declval<const WrapperType&>()));
+
+    template <typename OtherStringType,
+              detail::enable_if_t <
+                  detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                      basic_json_t, JSONSerializer<OtherStringType>, OtherStringType,
+                                      detail::string_type_wrapper<OtherStringType>>::value, int > = 0 >
+    void other_string_to_json(const OtherStringType& str)
+    {
+        JSONSerializer<OtherStringType>::to_json(*this, detail::string_type_wrapper<OtherStringType> {str});
+    }
+
+    template < typename OtherStringType,
+               detail::enable_if_t <
+                   !detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                        basic_json_t, JSONSerializer<OtherStringType>, OtherStringType,
+                                        detail::string_type_wrapper<OtherStringType>>::value, int > = 0 >
+    void other_string_to_json(const OtherStringType& str)
+    {
+        JSONSerializer<OtherStringType>::to_json(*this, str);
+    }
+
+    template <typename OtherObjectType,
+              detail::enable_if_t <
+                  detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                      basic_json_t, JSONSerializer<OtherObjectType>, OtherObjectType,
+                                      detail::object_type_wrapper<OtherObjectType>>::value, int > = 0 >
+    void other_object_to_json(const OtherObjectType& obj)
+    {
+        JSONSerializer<OtherObjectType>::to_json(*this, detail::object_type_wrapper<OtherObjectType> {obj});
+    }
+
+    template < typename OtherObjectType,
+               detail::enable_if_t <
+                   !detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                        basic_json_t, JSONSerializer<OtherObjectType>, OtherObjectType,
+                                        detail::object_type_wrapper<OtherObjectType>>::value, int > = 0 >
+    void other_object_to_json(const OtherObjectType& obj)
+    {
+        JSONSerializer<OtherObjectType>::to_json(*this, obj);
+    }
+
+    template <typename OtherArrayType,
+              detail::enable_if_t <
+                  detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                      basic_json_t, JSONSerializer<OtherArrayType>, OtherArrayType,
+                                      detail::array_type_wrapper<OtherArrayType>>::value, int > = 0 >
+    void other_array_to_json(const OtherArrayType& arr)
+    {
+        JSONSerializer<OtherArrayType>::to_json(*this, detail::array_type_wrapper<OtherArrayType> {arr});
+    }
+
+    template < typename OtherArrayType,
+               detail::enable_if_t <
+                   !detail::is_detected<serializer_has_to_json_with_type_wrapper,
+                                        basic_json_t, JSONSerializer<OtherArrayType>, OtherArrayType,
+                                        detail::array_type_wrapper<OtherArrayType>>::value, int > = 0 >
+    void other_array_to_json(const OtherArrayType& arr)
+    {
+        JSONSerializer<OtherArrayType>::to_json(*this, arr);
+    }
+
+  public:
     /// @brief create a JSON value from an existing one
     /// @sa https://json.nlohmann.me/api/basic_json/basic_json/
     template < typename BasicJsonType,
                detail::enable_if_t <
                    detail::is_basic_json<BasicJsonType>::value&& !std::is_same<basic_json, BasicJsonType>::value, int > = 0 >
-    basic_json(const BasicJsonType& val)
+    JSON_EXPLICIT basic_json(const BasicJsonType& val)
     {
         using other_boolean_t = typename BasicJsonType::boolean_t;
         using other_number_float_t = typename BasicJsonType::number_float_t;
@@ -20080,13 +20239,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                 JSONSerializer<other_number_unsigned_t>::to_json(*this, val.template get<other_number_unsigned_t>());
                 break;
             case value_t::string:
-                JSONSerializer<other_string_t>::to_json(*this, val.template get_ref<const other_string_t&>());
+                other_string_to_json(val.template get_ref<const other_string_t&>());
                 break;
             case value_t::object:
-                JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
+                other_object_to_json(val.template get_ref<const other_object_t&>());
                 break;
             case value_t::array:
-                JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
+                other_array_to_json(val.template get_ref<const other_array_t&>());
                 break;
             case value_t::binary:
                 JSONSerializer<other_binary_t>::to_json(*this, val.template get_ref<const other_binary_t&>());
@@ -20881,7 +21040,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                    int > = 0 >
     BasicJsonType get_impl(detail::priority_tag<2> /*unused*/) const
     {
-        return *this;
+        return BasicJsonType(*this);
     }
 
     /*!

tests/src/unit-alt-string.cpp

@@ -10,7 +10,9 @@
 #include "doctest_compatibility.h"
 
 #include <nlohmann/json.hpp>
+using nlohmann::json;
 
+#include <iostream>
 #include <string>
 #include <utility>
 
@@ -308,17 +310,144 @@ TEST_CASE("alternative string type")
 
     SECTION("JSON pointer")
     {
-        // conversion from json to alt_json fails to compile (see #3425);
-        // attempted fix(*) produces: [[['b','a','r'],['b','a','z']]] (with each char being an integer)
-        // (*) disable implicit conversion for json_refs of any basic_json type
-        // alt_json j = R"(
-        // {
-        //     "foo": ["bar", "baz"]
-        // }
-        // )"_json;
         auto j = alt_json::parse(R"({"foo": ["bar", "baz"]})");
 
         CHECK(j.at(alt_json::json_pointer("/foo/0")) == j["foo"][0]);
         CHECK(j.at(alt_json::json_pointer("/foo/1")) == j["foo"][1]);
     }
+
+    SECTION("conversion (#3425)")
+    {
+        SECTION("string")
+        {
+            SECTION("json to alt_json")
+            {
+                json j("foo");
+#if JSON_USE_IMPLICIT_CONVERSIONS
+                alt_json aj = j;
+#else
+                alt_json aj = alt_json(j);
+#endif
+
+                alt_string as = aj.dump();
+                CHECK(j.is_string());
+                CHECK(j.dump() == "\"foo\"");
+                CHECK(j.dump() == std::string(as.data(), as.size()));
+            }
+
+            SECTION("alt_json to json")
+            {
+                alt_json aj("foo");
+#if JSON_USE_IMPLICIT_CONVERSIONS
+                json j = aj;
+#else
+                json j = json(aj);
+#endif
+
+                alt_string as = aj.dump();
+                CHECK(aj.is_string());
+                CHECK(j.dump() == "\"foo\"");
+                CHECK(j.dump() == std::string(as.data(), as.size()));
+            }
+        }
+
+        SECTION("array")
+        {
+            SECTION("json to alt_json")
+            {
+                json j{"foo"};
+#if JSON_USE_IMPLICIT_CONVERSIONS
+                alt_json aj = j;
+#else
+                alt_json aj = alt_json(j);
+#endif
+
+                alt_string as = aj.dump();
+                CHECK(j.is_array());
+                CHECK(j.dump() == "[\"foo\"]");
+                CHECK(j.dump() == std::string(as.data(), as.size()));
+            }
+
+            SECTION("alt_json to json")
+            {
+                alt_json aj{"foo"};
+#if JSON_USE_IMPLICIT_CONVERSIONS
+                json j = aj;
+#else
+                json j = json(aj);
+#endif
+
+                alt_string as = aj.dump();
+                CHECK(aj.is_array());
+                CHECK(j.dump() == "[\"foo\"]");
+                CHECK(j.dump() == std::string(as.data(), as.size()));
+            }
+        }
+
+        SECTION("object")
+        {
+            SECTION("json to alt_json")
+            {
+                json j{{"foo", {"bar", "baz"}}};
+#if JSON_USE_IMPLICIT_CONVERSIONS
+                alt_json aj = j;
+#else
+                alt_json aj = alt_json(j);
+#endif
+
+                alt_string as = aj.dump();
+                CHECK(j.is_object());
+                CHECK(j.dump() == "{\"foo\":[\"bar\",\"baz\"]}");
+                CHECK(j.dump() == std::string(as.data(), as.size()));
+            }
+
+            SECTION("alt_json to json")
+            {
+                alt_json aj{{"foo", {"bar", "baz"}}};
+#if JSON_USE_IMPLICIT_CONVERSIONS
+                json j = aj;
+#else
+                json j = json(aj);
+#endif
+
+                alt_string as = aj.dump();
+                CHECK(aj.is_object());
+                CHECK(j.dump() == "{\"foo\":[\"bar\",\"baz\"]}");
+                CHECK(j.dump() == std::string(as.data(), as.size()));
+            }
+        }
+
+        SECTION("binary")
+        {
+            SECTION("json to alt_json")
+            {
+                auto j = json::binary({1, 2, 3, 4}, 128);
+#if JSON_USE_IMPLICIT_CONVERSIONS
+                alt_json aj = j;
+#else
+                alt_json aj = alt_json(j);
+#endif
+
+                alt_string as = aj.dump();
+                CHECK(j.is_binary());
+                CHECK(j.dump() == "{\"bytes\":[1,2,3,4],\"subtype\":128}");
+                CHECK(j.dump() == std::string(as.data(), as.size()));
+            }
+
+            SECTION("alt_json to json")
+            {
+                auto aj = alt_json::binary({1, 2, 3, 4}, 128);
+#if JSON_USE_IMPLICIT_CONVERSIONS
+                json j = aj;
+#else
+                json j = json(aj);
+#endif
+
+                alt_string as = aj.dump();
+                CHECK(aj.is_binary());
+                CHECK(j.dump() == "{\"bytes\":[1,2,3,4],\"subtype\":128}");
+                CHECK(j.dump() == std::string(as.data(), as.size()));
+            }
+        }
+    }
 }

tests/src/unit-regression1.cpp

@@ -1467,7 +1467,11 @@ TEST_CASE("regression tests 1")
 
     SECTION("issue #972 - Segmentation fault on G++ when trying to assign json string literal to custom json type")
     {
+#if JSON_USE_IMPLICIT_CONVERSIONS
         my_json foo = R"([1, 2, 3])"_json;
+#else
+        my_json foo = my_json(R"([1, 2, 3])"_json);
+#endif
     }
 
     SECTION("issue #977 - Assigning between different json types")
@@ -1478,7 +1482,11 @@ TEST_CASE("regression tests 1")
         CHECK(lj.size() == 1);
         CHECK(lj["x"] == 3);
         CHECK(ff.x == 3);
+#if JSON_USE_IMPLICIT_CONVERSIONS
         nlohmann::json nj = lj;                // This line works as expected
+#else
+        nlohmann::json nj = nlohmann::json(lj);                // This line works as expected
+#endif
     }
 }
 

tests/src/unit-regression2.cpp

@@ -792,12 +792,12 @@ TEST_CASE("regression tests 2")
         CHECK(test1.dump() == "{\"root\":{}}");
 
         ordered_json test2;
-        test2[ordered_json::json_pointer(p)] = json::object();
+        test2[ordered_json::json_pointer(p)] = ordered_json::object();
         CHECK(test2.dump() == "{\"root\":{}}");
 
         // json::json_pointer and ordered_json::json_pointer are the same type; behave as above
         ordered_json test3;
-        test3[json::json_pointer(p)] = json::object();
+        test3[json::json_pointer(p)] = ordered_json::object();
         CHECK(std::is_same<json::json_pointer::string_t, ordered_json::json_pointer::string_t>::value);
         CHECK(test3.dump() == "{\"root\":{}}");
     }
@@ -877,7 +877,8 @@ TEST_CASE("regression tests 2")
         CHECK(td.str == "value");
     }
 
-#ifdef JSON_HAS_CPP_20
+    // this is no longer supported when implicit conversions are disabled
+#if defined(JSON_HAS_CPP_20) && JSON_USE_IMPLICIT_CONVERSIONS
     SECTION("issue #3312 - Parse to custom class from unordered_json breaks on G++11.2.0 with C++20")
     {
         // see test for #3171

tests/src/unit-udt.cpp

@@ -695,14 +695,22 @@ TEST_CASE("different basic_json types conversions")
     SECTION("null")
     {
         json j;
+#if JSON_USE_IMPLICIT_CONVERSIONS
         custom_json cj = j;
+#else
+        custom_json cj = custom_json(j);
+#endif
         CHECK(cj == nullptr);
     }
 
     SECTION("boolean")
     {
         json j = true;
+#if JSON_USE_IMPLICIT_CONVERSIONS
         custom_json cj = j;
+#else
+        custom_json cj = custom_json(j);
+#endif
         CHECK(cj == true);
     }
 
@@ -710,49 +718,77 @@ TEST_CASE("different basic_json types conversions")
     {
         json j(json::value_t::discarded);
         custom_json cj;
+#if JSON_USE_IMPLICIT_CONVERSIONS
         CHECK_NOTHROW(cj = j);
+#else
+        CHECK_NOTHROW(cj = custom_json(j));
+#endif
         CHECK(cj.type() == custom_json::value_t::discarded);
     }
 
     SECTION("array")
     {
         json j = {1, 2, 3};
+#if JSON_USE_IMPLICIT_CONVERSIONS
         custom_json cj = j;
+#else
+        custom_json cj = custom_json(j);
+#endif
         CHECK((cj == std::vector<int> {1, 2, 3}));
     }
 
     SECTION("integer")
     {
         json j = 42;
+#if JSON_USE_IMPLICIT_CONVERSIONS
         custom_json cj = j;
+#else
+        custom_json cj = custom_json(j);
+#endif
         CHECK(cj == 42);
     }
 
     SECTION("float")
     {
         json j = 42.0;
+#if JSON_USE_IMPLICIT_CONVERSIONS
         custom_json cj = j;
+#else
+        custom_json cj = custom_json(j);
+#endif
         CHECK(cj == 42.0);
     }
 
     SECTION("unsigned")
     {
         json j = 42u;
+#if JSON_USE_IMPLICIT_CONVERSIONS
         custom_json cj = j;
+#else
+        custom_json cj = custom_json(j);
+#endif
         CHECK(cj == 42u);
     }
 
     SECTION("string")
     {
         json j = "forty-two";
+#if JSON_USE_IMPLICIT_CONVERSIONS
         custom_json cj = j;
+#else
+        custom_json cj = custom_json(j);
+#endif
         CHECK(cj == "forty-two");
     }
 
     SECTION("binary")
     {
         json j = json::binary({1, 2, 3}, 42);
+#if JSON_USE_IMPLICIT_CONVERSIONS
         custom_json cj = j;
+#else
+        custom_json cj = custom_json(j);
+#endif
         CHECK(cj.get_binary().subtype() == 42);
         std::vector<std::uint8_t> cv = cj.get_binary();
         std::vector<std::uint8_t> v = j.get_binary();
@@ -762,7 +798,11 @@ TEST_CASE("different basic_json types conversions")
     SECTION("object")
     {
         json j = {{"forty", "two"}};
+#if JSON_USE_IMPLICIT_CONVERSIONS
         custom_json cj = j;
+#else
+        custom_json cj = custom_json(j);
+#endif
         auto m = j.get<std::map<std::string, std::string>>();
         CHECK(cj == m);
     }