Keep the Qt keyword macros in the test from failing -Wunused-macros

Clang (-Werror) rejected the macros that the test defines but the library
must not use, and clang-tidy asked for parentheses around the arguments
of the Q_FOREACH imitation, where the variable is a declaration.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

.github/workflows/windows.yml

@@ -166,19 +166,21 @@ jobs:
       # link, but the binaries clang 11.0.1 and clang 18.1.8 then produce crash
       # before doctest prints its first line - 39 of 102 tests on clang 18.
       # Keep the objects small by splitting the test files instead.
-      # Objects with more than 65535 sections fail to link with "relocation
-      # truncated to fit: IMAGE_REL_AMD64_REL32 against `.rdata'": the MinGW
-      # linker stores the section an associative COMDAT section belongs to in
-      # 16 bits (x_associated in binutils' include/coff/internal.h), so it
-      # discards the jump tables of inline functions together with the wrong
-      # function. Each basic_json specialization a test file instantiates adds
-      # many sections, so test a second one in a file of its own.
+      # The tests link with LLD: GNU ld fails on objects with more than 32767
+      # sections with "relocation truncated to fit: IMAGE_REL_AMD64_REL32
+      # against `.rdata'", as it stores the section an associative COMDAT
+      # section belongs to in 16 bits (x_associated in binutils'
+      # include/coff/internal.h) and so discards the jump tables of inline
+      # functions together with the wrong function. Each basic_json
+      # specialization and input type a test file instantiates adds many
+      # sections, so unit-msgpack.cpp and unit-regression2.cpp kept crossing
+      # that limit as the library grew.
       - name: Run CMake
         run: cmake -S . -B build ^
              -DCMAKE_CXX_COMPILER="C:/Program Files/LLVM/bin/clang++.exe" ^
              -DCMAKE_CXX_FLAGS="--target=x86_64-w64-mingw32 -stdlib=libstdc++ -pthread" ^
              -DCMAKE_CXX_FLAGS_DEBUG="-g0" ^
-             -DCMAKE_EXE_LINKER_FLAGS="-lwinpthread" ^
+             -DCMAKE_EXE_LINKER_FLAGS="-fuse-ld=lld -lwinpthread" ^
              -G"MinGW Makefiles" ^
              -DCMAKE_BUILD_TYPE=Debug ^
              -DJSON_BuildTests=On

docs/mkdocs/docs/community/quality_assurance.md

@@ -135,6 +135,9 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
   headers are included.
 - [x] On Windows, the library is compiled with `<Windows.h>` being included to detect and avoid common bugs (see
   [`unit-windows_h.cpp`](https://github.com/nlohmann/json/blob/develop/tests/src/unit-windows_h.cpp)).
+- [x] The library is compiled with Qt's keyword macros (`slots`, `signals`, `emit`, `foreach`, `forever`) being defined
+  to make sure it does not use them as identifiers (see
+  [`unit-qt_keywords.cpp`](https://github.com/nlohmann/json/blob/develop/tests/src/unit-qt_keywords.cpp)).
 - [x] The library is compiled with exceptions disabled to support alternative means of error handling.
 
 ## Stable public API

include/nlohmann/detail/conversions/to_json.hpp

@@ -13,7 +13,7 @@
     #include <optional> // optional
 #endif
 
-#include <iterator> // begin, end
+#include <iterator> // begin, end, make_move_iterator, move_iterator
 #include <memory> // allocator_traits
 #include <string> //  basic_string, char_traits
 #include <tuple> // tuple, get
@@ -48,6 +48,32 @@ namespace detail
  * leave j with the type of the new value, but the pointer to the destroyed old one.
  */
 
+// a move iterator over the elements of an rvalue container, unless they are
+// const (e.g., std::set): libstdc++ before GCC 5 defines the reference of a
+// std::move_iterator as value_type&&, which cannot bind to a const element
+template<typename Iterator>
+std::move_iterator<Iterator> make_move_iterator_if_mutable_impl(const Iterator& it, std::true_type /*mutable*/)
+{
+    return std::make_move_iterator(it);
+}
+
+template<typename Iterator>
+Iterator make_move_iterator_if_mutable_impl(const Iterator& it, std::false_type /*mutable*/)
+{
+    return it;
+}
+
+template<typename Iterator>
+using is_mutable_iterator = std::integral_constant < bool,
+      !std::is_const<typename std::remove_reference<decltype(*std::declval<Iterator&>())>::type>::value >;
+
+template<typename Iterator>
+auto make_move_iterator_if_mutable(const Iterator& it)
+-> decltype(make_move_iterator_if_mutable_impl(it, is_mutable_iterator<Iterator> {}))
+{
+    return make_move_iterator_if_mutable_impl(it, is_mutable_iterator<Iterator> {});
+}
+
 template<value_t> struct external_constructor;
 
 template<>
@@ -174,7 +200,7 @@ struct external_constructor<value_t::array>
         using std::begin;
         using std::end;
 
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(std::make_move_iterator(begin(arr)), std::make_move_iterator(end(arr))));
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(make_move_iterator_if_mutable(begin(arr)), make_move_iterator_if_mutable(end(arr))));
         j.replace_value(value_t::array, value);
     }
 
@@ -235,7 +261,7 @@ struct external_constructor<value_t::object>
         using std::begin;
         using std::end;
 
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::object_t>(std::make_move_iterator(begin(obj)), std::make_move_iterator(end(obj))));
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::object_t>(make_move_iterator_if_mutable(begin(obj)), make_move_iterator_if_mutable(end(obj))));
         j.replace_value(value_t::object, value);
     }
 
@@ -413,25 +439,27 @@ using is_movable_container_rvalue = negation<disjunction<
                                     std::is_const<T>,
                                     has_dedicated_to_json<T>,
                                     is_basic_json<T>,
-                                    is_range_view_type<T>,
                                     is_enum_keyed_map_type<T>,
                                     std::is_same<T, std::vector<bool>>>>;
 
-// rvalue array-like containers
+// rvalue array-like containers; object types are ruled out before views are
+// checked, as std::ranges::view<T> for the object_t of an ordered_json would
+// need that ordered_json to be complete (GCC 11, see #3312)
 template<typename BasicJsonType, typename T>
 using is_rvalue_array_to_json = conjunction<is_movable_container_rvalue<T>,
+      negation<is_compatible_object_type<BasicJsonType, T>>,
+      negation<is_range_view_type<T>>,
       is_compatible_array_type<BasicJsonType, T>,
       negation<disjunction<
       std::is_same<T, typename BasicJsonType::array_t>,
       std::is_same<T, typename BasicJsonType::binary_t>,
-      is_compatible_object_type<BasicJsonType, T>,
       is_compatible_string_type<BasicJsonType, T>,
       is_compatible_binary_type<BasicJsonType, T>>>>;
 
 // rvalue containers: their elements are moved instead of copied
 template<typename BasicJsonType, typename CompatibleArrayType,
          enable_if_t<is_rvalue_array_to_json<BasicJsonType, CompatibleArrayType>::value, int> = 0>
-inline void to_json(BasicJsonType& j, CompatibleArrayType && arr)
+inline void to_json(BasicJsonType& j, CompatibleArrayType && arr) // NOLINT(cppcoreguidelines-missing-std-forward)
 {
     external_constructor<value_t::array>::construct_moving(j, arr);
 }
@@ -509,7 +537,8 @@ inline void to_json(BasicJsonType& j, const EnumKeyedMap& map)
 }
 #endif
 
-// rvalue object-like containers
+// rvalue object-like containers (views have no key_type and mapped_type, so
+// they are no compatible object type)
 template<typename BasicJsonType, typename T>
 using is_rvalue_object_to_json = conjunction<is_movable_container_rvalue<T>,
       negation<std::is_same<T, typename BasicJsonType::object_t>>,
@@ -517,7 +546,7 @@ using is_rvalue_object_to_json = conjunction<is_movable_container_rvalue<T>,
 
 template<typename BasicJsonType, typename CompatibleObjectType,
          enable_if_t<is_rvalue_object_to_json<BasicJsonType, CompatibleObjectType>::value, int> = 0>
-inline void to_json(BasicJsonType& j, CompatibleObjectType && obj)
+inline void to_json(BasicJsonType& j, CompatibleObjectType && obj) // NOLINT(cppcoreguidelines-missing-std-forward)
 {
     external_constructor<value_t::object>::construct_moving(j, obj);
 }

include/nlohmann/detail/conversions/zmij.hpp

@@ -185,7 +185,7 @@ JSON_HEDLEY_ALWAYS_INLINE shortest_decimal to_shortest(std::uint64_t bits) noexc
     const uint128_parts p = umul192_hi128(p10.high, p10.low, bin_sig << static_cast<unsigned>(shift));
     std::uint64_t integral = p.high >> static_cast<unsigned>(extra_shift);
     // (no casts in the shifts: MSVC 2015 warns C4554 on them despite the parentheses)
-    constexpr unsigned fractional_low_shift = static_cast<unsigned>(extra_shift);
+    constexpr auto fractional_low_shift = static_cast<unsigned>(extra_shift);
     constexpr unsigned fractional_high_shift = 64u - fractional_low_shift;
     const std::uint64_t fractional = (p.high << fractional_high_shift) | (p.low >> fractional_low_shift);
     std::uint64_t digit = 0;

include/nlohmann/detail/exceptions.hpp

@@ -494,8 +494,7 @@ JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE void throw_patch_missing_member(c
     static_cast<void>(string_type);
     static_cast<void>(val);
     // context-sensitive error message
-    const std::string error_msg = (op == "op") ? std::string("operation") : concat("operation '", op, '\'');
-    JSON_THROW(parse_error::create(exception_id::patch_invalid_operation, 0, concat(error_msg, string_type ? " must have string member '" : " must have member '", member, "'"), &val));
+    JSON_THROW(parse_error::create(exception_id::patch_invalid_operation, 0, concat((op == "op") ? std::string("operation") : concat("operation '", op, '\''), string_type ? " must have string member '" : " must have member '", member, "'"), &val));
 }
 
 template<typename StringType, typename BasicJsonType>

include/nlohmann/detail/iterators/iter_impl.hpp

@@ -680,12 +680,12 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
     {
         JSON_ASSERT(m_object != nullptr);
 
-        if (JSON_HEDLEY_LIKELY(m_object->is_object()))
+        if (JSON_HEDLEY_UNLIKELY(!m_object->is_object()))
         {
-            return m_it.object_iterator->first;
+            throw_literal<invalid_iterator>(exception_id::iterator_key_not_object, "cannot use key() for non-object iterators", m_object);
         }
 
-        throw_literal<invalid_iterator>(exception_id::iterator_key_not_object, "cannot use key() for non-object iterators", m_object);
+        return m_it.object_iterator->first;
     }
 
     /*!

include/nlohmann/detail/json_pointer.hpp

@@ -11,6 +11,7 @@
 #include <algorithm> // all_of
 #include <cctype> // isdigit
 #include <cerrno> // errno, ERANGE
+#include <cstddef> // size_t
 #include <cstdlib> // strtoull
 #ifndef JSON_NO_IO
     #include <iosfwd> // ostream
@@ -334,7 +335,7 @@ class json_pointer
                 {
                     break; // not a plain number: let strtoull decide
                 }
-                acc = static_cast<size_type>(acc * 10 + static_cast<size_type>(c - '0'));
+                acc = static_cast<size_type>((acc * 10) + static_cast<size_type>(c - '0'));
                 if (JSON_HEDLEY_UNLIKELY(i == s.size() - 1))
                 {
                     idx = acc;
@@ -524,34 +525,34 @@ class json_pointer
             {}
         };
 
-        std::vector<slot> slots;
+        std::vector<slot> table;
         std::size_t used = 0;
 
         static std::size_t hash_of(std::size_t parent, const string_t& token) noexcept
         {
-            std::size_t h = parent * static_cast<std::size_t>(0x9E3779B97F4A7C15ULL);
+            std::size_t h = parent * static_cast<std::size_t>(0x9E3779B97F4A7C15ULL & (std::numeric_limits<std::size_t>::max)());
             for (std::size_t i = 0; i < token.size(); ++i)
             {
-                h = (h ^ static_cast<unsigned char>(token[i])) * static_cast<std::size_t>(0x100000001B3ULL);
+                h = (h ^ static_cast<unsigned char>(token[i])) * static_cast<std::size_t>(0x100000001B3ULL & (std::numeric_limits<std::size_t>::max)());
             }
             return h ^ (h >> 29u);
         }
 
         void grow()
         {
-            std::vector<slot> old(slots.size() * 2);
-            old.swap(slots);
-            const std::size_t mask = slots.size() - 1;
+            std::vector<slot> old(table.size() * 2);
+            old.swap(table);
+            const std::size_t mask = table.size() - 1;
             for (const auto& s : old)
             {
                 if (s.token != nullptr)
                 {
                     std::size_t i = s.hash & mask;
-                    while (slots[i].token != nullptr)
+                    while (table[i].token != nullptr)
                     {
                         i = (i + 1) & mask;
                     }
-                    slots[i] = s;
+                    table[i] = s;
                 }
             }
         }
@@ -564,7 +565,7 @@ class json_pointer
 
         // start with the empty prefix only
         prefix_tree()
-            : slots(16)
+            : table(16)
             , parent(1, 0)
             , is_array(1, false)
         {}
@@ -574,20 +575,20 @@ class json_pointer
         std::size_t add_child(std::size_t id, const string_t& reference_token)
         {
             const std::size_t hash = hash_of(id, reference_token);
-            const std::size_t mask = slots.size() - 1;
+            const std::size_t mask = table.size() - 1;
             std::size_t i = hash & mask;
-            while (slots[i].token != nullptr)
+            while (table[i].token != nullptr)
             {
-                if (slots[i].hash == hash && slots[i].parent == id && *slots[i].token == reference_token)
+                if (table[i].hash == hash && table[i].parent == id && *table[i].token == reference_token)
                 {
-                    return slots[i].id;
+                    return table[i].id;
                 }
                 i = (i + 1) & mask;
             }
 
             // new prefix
             const std::size_t child = parent.size();
-            slots[i] = slot(hash, id, &reference_token, child);
+            table[i] = slot(hash, id, &reference_token, child);
             if (reference_token == "0")
             {
                 is_array[id] = true;
@@ -596,7 +597,7 @@ class json_pointer
             is_array.push_back(false);
 
             // keep the load factor below 1/2
-            if (++used * 2 > slots.size())
+            if (++used * 2 > table.size())
             {
                 grow();
             }

include/nlohmann/json.hpp

@@ -29,6 +29,7 @@
 #endif  // JSON_NO_IO
 #include <iterator> // make_move_iterator, random_access_iterator_tag
 #include <limits> // numeric_limits
+#include <map> // map
 #include <memory> // unique_ptr
 #include <set> // swap, operator!=
 #include <stdexcept> // length_error
@@ -754,26 +755,20 @@ private:
         // one level deep); stops at the first structured child it meets
         static bool all_children_leaves(const basic_json& v) noexcept
         {
+            // array_t only needs forward iterators (see custom_array_type)
             if (v.m_data.m_type == value_t::array)
             {
                 const auto& a = *v.m_data.m_value.array;
-                for (auto it = a.rbegin(); it != a.rend(); ++it)
+                return std::all_of(a.begin(), a.end(), [](const basic_json & el)
                 {
-                    if (!has_no_children(*it))
-                    {
-                        return false;
-                    }
-                }
-                return true;
+                    return has_no_children(el);
+                });
             }
-            for (const auto& el : *v.m_data.m_value.object)
+            const auto& o = *v.m_data.m_value.object;
+            return std::all_of(o.begin(), o.end(), [](const typename object_t::value_type & el)
             {
-                if (!has_no_children(el.second))
-                {
-                    return false;
-                }
-            }
-            return true;
+                return has_no_children(el.second);
+            });
         }
 
         // The walk in destroy_container() may take the children of a
@@ -1230,7 +1225,7 @@ public:
     }
 
     template < typename O = object_t, detail::enable_if_t < detail::has_stable_elements<O>::value, int > = 0 >
-    static constexpr std::size_t object_capacity() noexcept
+    std::size_t object_capacity() const noexcept
     {
         return 0;
     }
@@ -1242,7 +1237,7 @@ public:
     }
 
     template < typename O = object_t, detail::enable_if_t < !detail::has_stable_elements<O>::value && !detail::is_nlohmann_ordered_map<O>::value, int > = 0 >
-    static constexpr std::size_t object_capacity() noexcept
+    std::size_t object_capacity() const noexcept
     {
         return detail::unknown_size();
     }
@@ -3043,18 +3038,21 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_iterator_range_of_null(const basic_json* obj)
     {
+        static_cast<void>(obj); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_range_of_null, detail::concat("cannot construct with iterators from ", obj->type_name()), obj));
     }
 
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_incompatible_reference_type(const basic_json& obj)
     {
+        static_cast<void>(obj); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(type_error::create(detail::exception_id::incompatible_reference_type, detail::concat("incompatible ReferenceType for get_ref, actual type is ", obj.type_name()), &obj));
     }
 
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_array_index_exceeds_size_type(size_type idx)
     {
+        static_cast<void>(idx); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(std::length_error(detail::concat("array index ", std::to_string(idx), " exceeds size_type")));
     }
 
@@ -3062,6 +3060,8 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_array_index_out_of_range(size_type idx, const basic_json& j)
     {
+        static_cast<void>(idx); // unused when JSON_NOEXCEPTION is defined
+        static_cast<void>(j);
         JSON_THROW(out_of_range::create(detail::exception_id::array_index_out_of_range, detail::concat("array index ", std::to_string(idx), " is out of range"), &j));
     }
 
@@ -3070,6 +3070,8 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_key_not_found(const KeyType& key, const basic_json& j)
     {
+        static_cast<void>(key); // unused when JSON_NOEXCEPTION is defined
+        static_cast<void>(j);
         JSON_THROW(out_of_range::create(detail::exception_id::key_not_found, detail::concat("key '", key, "' not found"), &j));
     }
 
@@ -4893,19 +4895,19 @@ public:
     iterator insert(const_iterator pos, const basic_json& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
+        if (JSON_HEDLEY_UNLIKELY(!is_array()))
         {
-            // check if iterator pos fits to this JSON value
-            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-            {
-                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-            }
-
-            // insert to array and return iterator
-            return insert_iterator(pos, val);
+            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
         }
 
-        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+        // check if iterator pos fits to this JSON value
+        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+        {
+            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+        }
+
+        // insert to array and return iterator
+        return insert_iterator(pos, val);
     }
 
     /// @brief inserts element into array
@@ -4913,21 +4915,21 @@ public:
     iterator insert(const_iterator pos, basic_json&& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
+        if (JSON_HEDLEY_UNLIKELY(!is_array()))
         {
-            // check if iterator pos fits to this JSON value
-            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-            {
-                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-            }
-
-            // moving into a local first keeps this safe even if val aliases
-            // an element of this array
-            basic_json tmp(std::move(val));
-            return insert_iterator(pos, std::move(tmp));
+            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
         }
 
-        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+        // check if iterator pos fits to this JSON value
+        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+        {
+            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+        }
+
+        // moving into a local first keeps this safe even if val aliases
+        // an element of this array
+        basic_json tmp(std::move(val));
+        return insert_iterator(pos, std::move(tmp));
     }
 
     /// @brief inserts copies of element into array
@@ -4935,19 +4937,19 @@ public:
     iterator insert(const_iterator pos, size_type cnt, const basic_json& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
+        if (JSON_HEDLEY_UNLIKELY(!is_array()))
         {
-            // check if iterator pos fits to this JSON value
-            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-            {
-                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-            }
-
-            // insert to array and return iterator
-            return insert_iterator(pos, cnt, val);
+            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
         }
 
-        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+        // check if iterator pos fits to this JSON value
+        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+        {
+            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+        }
+
+        // insert to array and return iterator
+        return insert_iterator(pos, cnt, val);
     }
 
     /// @brief inserts range of elements into array
@@ -5453,7 +5455,7 @@ public:
     // inline fast path for two values of the same non-owning scalar type; anything
     // else falls through to the out-of-line general comparison
 #define JSON_IMPLEMENT_SCALAR_FAST(op, null_result)                                                      \
-    if (lhs.m_data.m_type == rhs.m_data.m_type)                                                          \
+    if (lhs.m_data.m_type == rhs.m_data.m_type) /* NOLINT(readability/braces) */                         \
     {                                                                                                    \
         switch (lhs.m_data.m_type)                                                                       \
         {                                                                                                \

include/nlohmann/ordered_map.hpp

@@ -23,6 +23,7 @@
 #include <nlohmann/detail/abi_macros.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/type_traits.hpp>
+#include <nlohmann/thirdparty/hedley/hedley.hpp>
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 

single_include/nlohmann/json.hpp

@@ -29,6 +29,7 @@
 #endif  // JSON_NO_IO
 #include <iterator> // make_move_iterator, random_access_iterator_tag
 #include <limits> // numeric_limits
+#include <map> // map
 #include <memory> // unique_ptr
 #include <set> // swap, operator!=
 #include <stdexcept> // length_error
@@ -5794,8 +5795,7 @@ JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE void throw_patch_missing_member(c
     static_cast<void>(string_type);
     static_cast<void>(val);
     // context-sensitive error message
-    const std::string error_msg = (op == "op") ? std::string("operation") : concat("operation '", op, '\'');
-    JSON_THROW(parse_error::create(exception_id::patch_invalid_operation, 0, concat(error_msg, string_type ? " must have string member '" : " must have member '", member, "'"), &val));
+    JSON_THROW(parse_error::create(exception_id::patch_invalid_operation, 0, concat((op == "op") ? std::string("operation") : concat("operation '", op, '\''), string_type ? " must have string member '" : " must have member '", member, "'"), &val));
 }
 
 template<typename StringType, typename BasicJsonType>
@@ -6555,7 +6555,7 @@ NLOHMANN_JSON_NAMESPACE_END
     #include <optional> // optional
 #endif
 
-#include <iterator> // begin, end
+#include <iterator> // begin, end, make_move_iterator, move_iterator
 #include <memory> // allocator_traits
 #include <string> //  basic_string, char_traits
 #include <tuple> // tuple, get
@@ -7204,6 +7204,32 @@ namespace detail
  * leave j with the type of the new value, but the pointer to the destroyed old one.
  */
 
+// a move iterator over the elements of an rvalue container, unless they are
+// const (e.g., std::set): libstdc++ before GCC 5 defines the reference of a
+// std::move_iterator as value_type&&, which cannot bind to a const element
+template<typename Iterator>
+std::move_iterator<Iterator> make_move_iterator_if_mutable_impl(const Iterator& it, std::true_type /*mutable*/)
+{
+    return std::make_move_iterator(it);
+}
+
+template<typename Iterator>
+Iterator make_move_iterator_if_mutable_impl(const Iterator& it, std::false_type /*mutable*/)
+{
+    return it;
+}
+
+template<typename Iterator>
+using is_mutable_iterator = std::integral_constant < bool,
+      !std::is_const<typename std::remove_reference<decltype(*std::declval<Iterator&>())>::type>::value >;
+
+template<typename Iterator>
+auto make_move_iterator_if_mutable(const Iterator& it)
+-> decltype(make_move_iterator_if_mutable_impl(it, is_mutable_iterator<Iterator> {}))
+{
+    return make_move_iterator_if_mutable_impl(it, is_mutable_iterator<Iterator> {});
+}
+
 template<value_t> struct external_constructor;
 
 template<>
@@ -7330,7 +7356,7 @@ struct external_constructor<value_t::array>
         using std::begin;
         using std::end;
 
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(std::make_move_iterator(begin(arr)), std::make_move_iterator(end(arr))));
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(make_move_iterator_if_mutable(begin(arr)), make_move_iterator_if_mutable(end(arr))));
         j.replace_value(value_t::array, value);
     }
 
@@ -7391,7 +7417,7 @@ struct external_constructor<value_t::object>
         using std::begin;
         using std::end;
 
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::object_t>(std::make_move_iterator(begin(obj)), std::make_move_iterator(end(obj))));
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::object_t>(make_move_iterator_if_mutable(begin(obj)), make_move_iterator_if_mutable(end(obj))));
         j.replace_value(value_t::object, value);
     }
 
@@ -7569,25 +7595,27 @@ using is_movable_container_rvalue = negation<disjunction<
                                     std::is_const<T>,
                                     has_dedicated_to_json<T>,
                                     is_basic_json<T>,
-                                    is_range_view_type<T>,
                                     is_enum_keyed_map_type<T>,
                                     std::is_same<T, std::vector<bool>>>>;
 
-// rvalue array-like containers
+// rvalue array-like containers; object types are ruled out before views are
+// checked, as std::ranges::view<T> for the object_t of an ordered_json would
+// need that ordered_json to be complete (GCC 11, see #3312)
 template<typename BasicJsonType, typename T>
 using is_rvalue_array_to_json = conjunction<is_movable_container_rvalue<T>,
+      negation<is_compatible_object_type<BasicJsonType, T>>,
+      negation<is_range_view_type<T>>,
       is_compatible_array_type<BasicJsonType, T>,
       negation<disjunction<
       std::is_same<T, typename BasicJsonType::array_t>,
       std::is_same<T, typename BasicJsonType::binary_t>,
-      is_compatible_object_type<BasicJsonType, T>,
       is_compatible_string_type<BasicJsonType, T>,
       is_compatible_binary_type<BasicJsonType, T>>>>;
 
 // rvalue containers: their elements are moved instead of copied
 template<typename BasicJsonType, typename CompatibleArrayType,
          enable_if_t<is_rvalue_array_to_json<BasicJsonType, CompatibleArrayType>::value, int> = 0>
-inline void to_json(BasicJsonType& j, CompatibleArrayType && arr)
+inline void to_json(BasicJsonType& j, CompatibleArrayType && arr) // NOLINT(cppcoreguidelines-missing-std-forward)
 {
     external_constructor<value_t::array>::construct_moving(j, arr);
 }
@@ -7665,7 +7693,8 @@ inline void to_json(BasicJsonType& j, const EnumKeyedMap& map)
 }
 #endif
 
-// rvalue object-like containers
+// rvalue object-like containers (views have no key_type and mapped_type, so
+// they are no compatible object type)
 template<typename BasicJsonType, typename T>
 using is_rvalue_object_to_json = conjunction<is_movable_container_rvalue<T>,
       negation<std::is_same<T, typename BasicJsonType::object_t>>,
@@ -7673,7 +7702,7 @@ using is_rvalue_object_to_json = conjunction<is_movable_container_rvalue<T>,
 
 template<typename BasicJsonType, typename CompatibleObjectType,
          enable_if_t<is_rvalue_object_to_json<BasicJsonType, CompatibleObjectType>::value, int> = 0>
-inline void to_json(BasicJsonType& j, CompatibleObjectType && obj)
+inline void to_json(BasicJsonType& j, CompatibleObjectType && obj) // NOLINT(cppcoreguidelines-missing-std-forward)
 {
     external_constructor<value_t::object>::construct_moving(j, obj);
 }
@@ -20715,12 +20744,12 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
     {
         JSON_ASSERT(m_object != nullptr);
 
-        if (JSON_HEDLEY_LIKELY(m_object->is_object()))
+        if (JSON_HEDLEY_UNLIKELY(!m_object->is_object()))
         {
-            return m_it.object_iterator->first;
+            throw_literal<invalid_iterator>(exception_id::iterator_key_not_object, "cannot use key() for non-object iterators", m_object);
         }
 
-        throw_literal<invalid_iterator>(exception_id::iterator_key_not_object, "cannot use key() for non-object iterators", m_object);
+        return m_it.object_iterator->first;
     }
 
     /*!
@@ -20947,6 +20976,7 @@ NLOHMANN_JSON_NAMESPACE_END
 #include <algorithm> // all_of
 #include <cctype> // isdigit
 #include <cerrno> // errno, ERANGE
+#include <cstddef> // size_t
 #include <cstdlib> // strtoull
 #ifndef JSON_NO_IO
     #include <iosfwd> // ostream
@@ -21277,7 +21307,7 @@ class json_pointer
                 {
                     break; // not a plain number: let strtoull decide
                 }
-                acc = static_cast<size_type>(acc * 10 + static_cast<size_type>(c - '0'));
+                acc = static_cast<size_type>((acc * 10) + static_cast<size_type>(c - '0'));
                 if (JSON_HEDLEY_UNLIKELY(i == s.size() - 1))
                 {
                     idx = acc;
@@ -21467,34 +21497,34 @@ class json_pointer
             {}
         };
 
-        std::vector<slot> slots;
+        std::vector<slot> table;
         std::size_t used = 0;
 
         static std::size_t hash_of(std::size_t parent, const string_t& token) noexcept
         {
-            std::size_t h = parent * static_cast<std::size_t>(0x9E3779B97F4A7C15ULL);
+            std::size_t h = parent * static_cast<std::size_t>(0x9E3779B97F4A7C15ULL & (std::numeric_limits<std::size_t>::max)());
             for (std::size_t i = 0; i < token.size(); ++i)
             {
-                h = (h ^ static_cast<unsigned char>(token[i])) * static_cast<std::size_t>(0x100000001B3ULL);
+                h = (h ^ static_cast<unsigned char>(token[i])) * static_cast<std::size_t>(0x100000001B3ULL & (std::numeric_limits<std::size_t>::max)());
             }
             return h ^ (h >> 29u);
         }
 
         void grow()
         {
-            std::vector<slot> old(slots.size() * 2);
-            old.swap(slots);
-            const std::size_t mask = slots.size() - 1;
+            std::vector<slot> old(table.size() * 2);
+            old.swap(table);
+            const std::size_t mask = table.size() - 1;
             for (const auto& s : old)
             {
                 if (s.token != nullptr)
                 {
                     std::size_t i = s.hash & mask;
-                    while (slots[i].token != nullptr)
+                    while (table[i].token != nullptr)
                     {
                         i = (i + 1) & mask;
                     }
-                    slots[i] = s;
+                    table[i] = s;
                 }
             }
         }
@@ -21507,7 +21537,7 @@ class json_pointer
 
         // start with the empty prefix only
         prefix_tree()
-            : slots(16)
+            : table(16)
             , parent(1, 0)
             , is_array(1, false)
         {}
@@ -21517,20 +21547,20 @@ class json_pointer
         std::size_t add_child(std::size_t id, const string_t& reference_token)
         {
             const std::size_t hash = hash_of(id, reference_token);
-            const std::size_t mask = slots.size() - 1;
+            const std::size_t mask = table.size() - 1;
             std::size_t i = hash & mask;
-            while (slots[i].token != nullptr)
+            while (table[i].token != nullptr)
             {
-                if (slots[i].hash == hash && slots[i].parent == id && *slots[i].token == reference_token)
+                if (table[i].hash == hash && table[i].parent == id && *table[i].token == reference_token)
                 {
-                    return slots[i].id;
+                    return table[i].id;
                 }
                 i = (i + 1) & mask;
             }
 
             // new prefix
             const std::size_t child = parent.size();
-            slots[i] = slot(hash, id, &reference_token, child);
+            table[i] = slot(hash, id, &reference_token, child);
             if (reference_token == "0")
             {
                 is_array[id] = true;
@@ -21539,7 +21569,7 @@ class json_pointer
             is_array.push_back(false);
 
             // keep the load factor below 1/2
-            if (++used * 2 > slots.size())
+            if (++used * 2 > table.size())
             {
                 grow();
             }
@@ -26454,7 +26484,7 @@ JSON_HEDLEY_ALWAYS_INLINE shortest_decimal to_shortest(std::uint64_t bits) noexc
     const uint128_parts p = umul192_hi128(p10.high, p10.low, bin_sig << static_cast<unsigned>(shift));
     std::uint64_t integral = p.high >> static_cast<unsigned>(extra_shift);
     // (no casts in the shifts: MSVC 2015 warns C4554 on them despite the parentheses)
-    constexpr unsigned fractional_low_shift = static_cast<unsigned>(extra_shift);
+    constexpr auto fractional_low_shift = static_cast<unsigned>(extra_shift);
     constexpr unsigned fractional_high_shift = 64u - fractional_low_shift;
     const std::uint64_t fractional = (p.high << fractional_high_shift) | (p.low >> fractional_low_shift);
     std::uint64_t digit = 0;
@@ -29704,6 +29734,8 @@ NLOHMANN_JSON_NAMESPACE_END
 
 // #include <nlohmann/detail/meta/type_traits.hpp>
 
+// #include <nlohmann/thirdparty/hedley/hedley.hpp>
+
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 
@@ -30788,26 +30820,20 @@ private:
         // one level deep); stops at the first structured child it meets
         static bool all_children_leaves(const basic_json& v) noexcept
         {
+            // array_t only needs forward iterators (see custom_array_type)
             if (v.m_data.m_type == value_t::array)
             {
                 const auto& a = *v.m_data.m_value.array;
-                for (auto it = a.rbegin(); it != a.rend(); ++it)
+                return std::all_of(a.begin(), a.end(), [](const basic_json & el)
                 {
-                    if (!has_no_children(*it))
-                    {
-                        return false;
-                    }
-                }
-                return true;
+                    return has_no_children(el);
+                });
             }
-            for (const auto& el : *v.m_data.m_value.object)
+            const auto& o = *v.m_data.m_value.object;
+            return std::all_of(o.begin(), o.end(), [](const typename object_t::value_type & el)
             {
-                if (!has_no_children(el.second))
-                {
-                    return false;
-                }
-            }
-            return true;
+                return has_no_children(el.second);
+            });
         }
 
         // The walk in destroy_container() may take the children of a
@@ -31264,7 +31290,7 @@ public:
     }
 
     template < typename O = object_t, detail::enable_if_t < detail::has_stable_elements<O>::value, int > = 0 >
-    static constexpr std::size_t object_capacity() noexcept
+    std::size_t object_capacity() const noexcept
     {
         return 0;
     }
@@ -31276,7 +31302,7 @@ public:
     }
 
     template < typename O = object_t, detail::enable_if_t < !detail::has_stable_elements<O>::value && !detail::is_nlohmann_ordered_map<O>::value, int > = 0 >
-    static constexpr std::size_t object_capacity() noexcept
+    std::size_t object_capacity() const noexcept
     {
         return detail::unknown_size();
     }
@@ -33077,18 +33103,21 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_iterator_range_of_null(const basic_json* obj)
     {
+        static_cast<void>(obj); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_range_of_null, detail::concat("cannot construct with iterators from ", obj->type_name()), obj));
     }
 
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_incompatible_reference_type(const basic_json& obj)
     {
+        static_cast<void>(obj); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(type_error::create(detail::exception_id::incompatible_reference_type, detail::concat("incompatible ReferenceType for get_ref, actual type is ", obj.type_name()), &obj));
     }
 
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_array_index_exceeds_size_type(size_type idx)
     {
+        static_cast<void>(idx); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(std::length_error(detail::concat("array index ", std::to_string(idx), " exceeds size_type")));
     }
 
@@ -33096,6 +33125,8 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_array_index_out_of_range(size_type idx, const basic_json& j)
     {
+        static_cast<void>(idx); // unused when JSON_NOEXCEPTION is defined
+        static_cast<void>(j);
         JSON_THROW(out_of_range::create(detail::exception_id::array_index_out_of_range, detail::concat("array index ", std::to_string(idx), " is out of range"), &j));
     }
 
@@ -33104,6 +33135,8 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_key_not_found(const KeyType& key, const basic_json& j)
     {
+        static_cast<void>(key); // unused when JSON_NOEXCEPTION is defined
+        static_cast<void>(j);
         JSON_THROW(out_of_range::create(detail::exception_id::key_not_found, detail::concat("key '", key, "' not found"), &j));
     }
 
@@ -34927,19 +34960,19 @@ public:
     iterator insert(const_iterator pos, const basic_json& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
+        if (JSON_HEDLEY_UNLIKELY(!is_array()))
         {
-            // check if iterator pos fits to this JSON value
-            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-            {
-                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-            }
-
-            // insert to array and return iterator
-            return insert_iterator(pos, val);
+            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
         }
 
-        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+        // check if iterator pos fits to this JSON value
+        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+        {
+            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+        }
+
+        // insert to array and return iterator
+        return insert_iterator(pos, val);
     }
 
     /// @brief inserts element into array
@@ -34947,21 +34980,21 @@ public:
     iterator insert(const_iterator pos, basic_json&& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
+        if (JSON_HEDLEY_UNLIKELY(!is_array()))
         {
-            // check if iterator pos fits to this JSON value
-            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-            {
-                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-            }
-
-            // moving into a local first keeps this safe even if val aliases
-            // an element of this array
-            basic_json tmp(std::move(val));
-            return insert_iterator(pos, std::move(tmp));
+            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
         }
 
-        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+        // check if iterator pos fits to this JSON value
+        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+        {
+            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+        }
+
+        // moving into a local first keeps this safe even if val aliases
+        // an element of this array
+        basic_json tmp(std::move(val));
+        return insert_iterator(pos, std::move(tmp));
     }
 
     /// @brief inserts copies of element into array
@@ -34969,19 +35002,19 @@ public:
     iterator insert(const_iterator pos, size_type cnt, const basic_json& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
+        if (JSON_HEDLEY_UNLIKELY(!is_array()))
         {
-            // check if iterator pos fits to this JSON value
-            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-            {
-                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-            }
-
-            // insert to array and return iterator
-            return insert_iterator(pos, cnt, val);
+            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
         }
 
-        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+        // check if iterator pos fits to this JSON value
+        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+        {
+            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+        }
+
+        // insert to array and return iterator
+        return insert_iterator(pos, cnt, val);
     }
 
     /// @brief inserts range of elements into array
@@ -35487,7 +35520,7 @@ public:
     // inline fast path for two values of the same non-owning scalar type; anything
     // else falls through to the out-of-line general comparison
 #define JSON_IMPLEMENT_SCALAR_FAST(op, null_result)                                                      \
-    if (lhs.m_data.m_type == rhs.m_data.m_type)                                                          \
+    if (lhs.m_data.m_type == rhs.m_data.m_type) /* NOLINT(readability/braces) */                         \
     {                                                                                                    \
         switch (lhs.m_data.m_type)                                                                       \
         {                                                                                                \

tests/CMakeLists.txt

@@ -118,7 +118,7 @@ endif()
 
 if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
     # avoid stack overflow, see https://github.com/nlohmann/json/issues/2955
-    json_test_set_test_options("test-bon8;test-cbor;test-msgpack;test-ubjson;test-bjdata;test-binary_formats" LINK_OPTIONS /STACK:4000000)
+    json_test_set_test_options("test-bon8;test-cbor;test-msgpack;test-ubjson;test-bjdata;test-bjdata_round_trip_draft2;test-bjdata_round_trip_draft3;test-binary_formats" LINK_OPTIONS /STACK:4000000)
 endif()
 
 # disable exceptions for test-disabled_exceptions

tests/src/bjdata_round_trip.hpp

@@ -0,0 +1,103 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include <cstdint> // uint8_t
+#include <vector> // vector
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+
+#include "round_trip_corpus.hpp"
+
+// The BJData round-trip invariants, split by the BJData version that turns a
+// corpus value into j1 (unit-bjdata_round_trip_draft2.cpp and
+// unit-bjdata_round_trip_draft3.cpp). They were part of unit-bjdata.cpp, but
+// took 80 % of its time; as separate tests, both halves run in parallel and
+// stay below the ctest timeout under Valgrind.
+namespace utils
+{
+
+// This checks what the parse_bjdata_fuzzer driver checks (see
+// tests/src/fuzzer-parse_bjdata.cpp), so that a regression shows up in CI
+// rather than as an OSS-Fuzz report: every value from_bjdata() returns
+// (j1) can be serialized with any combination of options, the result can
+// be parsed back (j2), and serializing j2 again with the same options
+// yields a value-equal result.
+//
+// Beyond the driver, this also checks that j2 equals j1 and that
+// serializing j2 reproduces the exact bytes, both except for values that
+// contain a binary value: a binary value is only written as a binary
+// value with Draft 3's optimized binary array, and otherwise read back as
+// an array of integers, for which the writer may choose different (but
+// equally valid) type markers when it is serialized again (see #5494).
+//
+// Values are compared with dump() rather than operator==, because a NaN
+// never compares equal to itself.
+//
+// Only the corpus values written with @a initial_version become j1; each j1
+// is then serialized with every combination of options, both versions
+// included.
+inline void check_bjdata_round_trip(const nlohmann::json::bjdata_version_t initial_version)
+{
+    using nlohmann::json;
+
+    struct options
+    {
+        bool use_size;
+        bool use_type;
+        json::bjdata_version_t version;
+    };
+    const std::vector<options> all_options =
+    {
+        {false, false, json::bjdata_version_t::draft2},
+        {true, false, json::bjdata_version_t::draft2},
+        {true, true, json::bjdata_version_t::draft2},
+        {false, false, json::bjdata_version_t::draft3},
+        {true, false, json::bjdata_version_t::draft3},
+        {true, true, json::bjdata_version_t::draft3},
+    };
+
+    for (const auto& j0 : utils::round_trip_corpus::values())
+    {
+        // turn the corpus value into a value as from_bjdata() returns it
+        for (const auto& initial : all_options)
+        {
+            if (initial.version != initial_version)
+            {
+                continue;
+            }
+
+            const json j1 = json::from_bjdata(json::to_bjdata(j0, initial.use_size, initial.use_type, initial.version));
+            const bool has_binary = utils::round_trip_corpus::contains_binary(j1);
+
+            for (const auto& o : all_options)
+            {
+                INFO("j1 = " << j1.dump() << ", use_size = " << o.use_size << ", use_type = " << o.use_type
+                     << ", draft3 = " << (o.version == json::bjdata_version_t::draft3));
+
+                const std::vector<std::uint8_t> vec = json::to_bjdata(j1, o.use_size, o.use_type, o.version);
+                json j2;
+                // anything the library writes must be parsable by the library
+                REQUIRE_NOTHROW(j2 = json::from_bjdata(vec));
+                const std::vector<std::uint8_t> vec2 = json::to_bjdata(j2, o.use_size, o.use_type, o.version);
+                CHECK(json::from_bjdata(vec2).dump() == j2.dump());
+
+                if (!has_binary)
+                {
+                    CHECK(j2.dump() == j1.dump());
+                    CHECK(vec2 == vec);
+                }
+            }
+        }
+    }
+}
+
+} // namespace utils

tests/src/unit-bjdata.cpp

@@ -28,7 +28,6 @@ using ordered_json = nlohmann::ordered_json;
 #include <fstream>
 #include <set>
 #include "make_test_data_available.hpp"
-#include "round_trip_corpus.hpp"
 #include "test_utils.hpp"
 #include "sax_countdown.hpp"
 using utils::SaxCountdown;
@@ -4441,70 +4440,6 @@ TEST_CASE("BJData use_type requires use_size")
     }
 }
 
-TEST_CASE("BJData round-trip invariants")
-{
-    // This checks what the parse_bjdata_fuzzer driver checks (see
-    // tests/src/fuzzer-parse_bjdata.cpp), so that a regression shows up in CI
-    // rather than as an OSS-Fuzz report: every value from_bjdata() returns
-    // (j1) can be serialized with any combination of options, the result can
-    // be parsed back (j2), and serializing j2 again with the same options
-    // yields a value-equal result.
-    //
-    // Beyond the driver, this also checks that j2 equals j1 and that
-    // serializing j2 reproduces the exact bytes, both except for values that
-    // contain a binary value: a binary value is only written as a binary
-    // value with Draft 3's optimized binary array, and otherwise read back as
-    // an array of integers, for which the writer may choose different (but
-    // equally valid) type markers when it is serialized again (see #5494).
-    //
-    // Values are compared with dump() rather than operator==, because a NaN
-    // never compares equal to itself.
-    struct options
-    {
-        bool use_size;
-        bool use_type;
-        json::bjdata_version_t version;
-    };
-    const std::vector<options> all_options =
-    {
-        {false, false, json::bjdata_version_t::draft2},
-        {true, false, json::bjdata_version_t::draft2},
-        {true, true, json::bjdata_version_t::draft2},
-        {false, false, json::bjdata_version_t::draft3},
-        {true, false, json::bjdata_version_t::draft3},
-        {true, true, json::bjdata_version_t::draft3},
-    };
-
-    for (const auto& j0 : utils::round_trip_corpus::values())
-    {
-        // turn the corpus value into a value as from_bjdata() returns it
-        for (const auto& initial : all_options)
-        {
-            const json j1 = json::from_bjdata(json::to_bjdata(j0, initial.use_size, initial.use_type, initial.version));
-            const bool has_binary = utils::round_trip_corpus::contains_binary(j1);
-
-            for (const auto& o : all_options)
-            {
-                INFO("j1 = " << j1.dump() << ", use_size = " << o.use_size << ", use_type = " << o.use_type
-                     << ", draft3 = " << (o.version == json::bjdata_version_t::draft3));
-
-                const std::vector<std::uint8_t> vec = json::to_bjdata(j1, o.use_size, o.use_type, o.version);
-                json j2;
-                // anything the library writes must be parsable by the library
-                REQUIRE_NOTHROW(j2 = json::from_bjdata(vec));
-                const std::vector<std::uint8_t> vec2 = json::to_bjdata(j2, o.use_size, o.use_type, o.version);
-                CHECK(json::from_bjdata(vec2).dump() == j2.dump());
-
-                if (!has_binary)
-                {
-                    CHECK(j2.dump() == j1.dump());
-                    CHECK(vec2 == vec);
-                }
-            }
-        }
-    }
-}
-
 TEST_CASE("BJData round trip of a binary value is value-stable, not byte-stable")
 {
     // OSS-Fuzz issue 474480402: a Draft 3 optimized binary array is read as a

tests/src/unit-bjdata_round_trip_draft2.cpp

@@ -0,0 +1,22 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include "bjdata_round_trip.hpp"
+
+// split from unit-bjdata.cpp, see bjdata_round_trip.hpp; the other half is in
+// unit-bjdata_round_trip_draft3.cpp
+
+TEST_CASE("BJData round-trip invariants (j1 written with Draft 2)")
+{
+    utils::check_bjdata_round_trip(json::bjdata_version_t::draft2);
+}

tests/src/unit-bjdata_round_trip_draft3.cpp

@@ -0,0 +1,22 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include "bjdata_round_trip.hpp"
+
+// split from unit-bjdata.cpp, see bjdata_round_trip.hpp; the other half is in
+// unit-bjdata_round_trip_draft2.cpp
+
+TEST_CASE("BJData round-trip invariants (j1 written with Draft 3)")
+{
+    utils::check_bjdata_round_trip(json::bjdata_version_t::draft3);
+}

tests/src/unit-constructor2.cpp

@@ -198,11 +198,11 @@ TEST_CASE("copy constructor and destructor across value types")
         const json src_uint = 7u;
         const json src_float = 2.5;
 
-        json c_null(src_null);
-        json c_bool(src_bool);
-        json c_int(src_int);
-        json c_uint(src_uint);
-        json c_float(src_float);
+        json c_null(src_null); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
+        json c_bool(src_bool); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
+        json c_int(src_int); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
+        json c_uint(src_uint); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
+        json c_float(src_float); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
 
         CHECK(c_null.is_null());
         CHECK(c_bool == true);
@@ -300,12 +300,12 @@ TEST_CASE("copy constructor and destructor across value types")
             REQUIRE(v.size() == 70);
 
             std::vector<json> copy(v);
-            CHECK(copy == v);
+            CHECK((copy == v));
 
             // mutating the copy leaves the original alone
             copy[5] = "changed";
             copy[6].push_back(1);
-            CHECK(copy != v);
+            CHECK((copy != v));
             CHECK(v[5] == std::string(5, 'x'));
             CHECK(v[6].size() == 3);
 

tests/src/unit-diagnostics.cpp

@@ -817,8 +817,8 @@ template<class Key, class T, class IgnoredLess = std::less<Key>,
              struct relocating_map : nlohmann::ordered_map<Key, T, IgnoredLess, Allocator>
 {
     using base_type = nlohmann::ordered_map<Key, T, IgnoredLess, Allocator>;
-    using typename base_type::iterator;
-    using typename base_type::Container;
+    using iterator = typename base_type::iterator;
+    using Container = typename base_type::Container;
     using base_type::base_type;
 
     template<typename... Args>

tests/src/unit-iterators1.cpp

@@ -1637,6 +1637,7 @@ TEST_CASE_TEMPLATE("reverse iteration and member access", Json, nlohmann::json,
     {
         Json j = {1, 2, 3, 4};
 
+        const std::vector<int> reversed = {4, 3, 2, 1};
         auto it = j.end();
         std::vector<int> seen;
         while (it != j.begin())
@@ -1644,7 +1645,7 @@ TEST_CASE_TEMPLATE("reverse iteration and member access", Json, nlohmann::json,
             --it;
             seen.push_back(it->template get<int>());
         }
-        CHECK(seen == std::vector<int> {4, 3, 2, 1});
+        CHECK(seen == reversed);
 
         auto it2 = j.end();
         auto old = it2--;
@@ -1656,14 +1657,14 @@ TEST_CASE_TEMPLATE("reverse iteration and member access", Json, nlohmann::json,
         {
             seen.push_back(r->template get<int>());
         }
-        CHECK(seen == std::vector<int> {4, 3, 2, 1});
+        CHECK(seen == reversed);
 
         seen.clear();
         for (auto r = j.crbegin(); r != j.crend(); ++r)
         {
-            seen.push_back(*r);
+            seen.push_back(r->template get<int>());
         }
-        CHECK(seen == std::vector<int> {4, 3, 2, 1});
+        CHECK(seen == reversed);
     }
 
     SECTION("object: -- and rbegin/rend")

tests/src/unit-json_pointer.cpp

@@ -1230,11 +1230,11 @@ TEST_CASE("JSON pointer array index tokens match strtoull semantics")
 
     SECTION("random tokens")
     {
-        std::mt19937 gen(42);
+        std::mt19937 gen(42); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed): reproducible
         const std::string alphabet = "0123456789012345678901234567890123456789-+ ex";
         for (int i = 0; i < 5000; ++i)
         {
-            std::string token(static_cast<std::size_t>(gen() % 23), '0');
+            std::string token(gen() % 23, '0');
             for (auto& c : token)
             {
                 c = alphabet[gen() % alphabet.size()];

tests/src/unit-large_json.cpp

@@ -13,8 +13,6 @@ using nlohmann::json;
 
 #include <algorithm>
 #include <string>
-#include <utility>
-#include <vector>
 
 TEST_CASE("tests on very large JSONs")
 {
@@ -55,24 +53,6 @@ const json* innermost_value(const json& j, std::size_t& depth)
     return current;
 }
 
-// The text of a value nested depth levels deep around the number 0. Level i is
-// an array if pattern[i % pattern.size()] is '[', and otherwise an object with
-// the single member "a", which every object type enumerates in the same order.
-std::string nested_text(std::size_t depth, const std::string& pattern)
-{
-    std::string text;
-    std::string closing;
-    for (std::size_t i = 0; i < depth; ++i)
-    {
-        const bool array = pattern[i % pattern.size()] == '[';
-        text += array ? "[" : "{\"a\":";
-        closing += array ? ']' : '}';
-    }
-    text += '0';
-    text.append(closing.rbegin(), closing.rend());
-    return text;
-}
-
 } // namespace
 
 TEST_CASE("tests on deeply nested JSONs")
@@ -244,385 +224,4 @@ TEST_CASE("tests on deeply nested JSONs")
             CHECK(*innermost_value(j, unused) == 0);
         }
     }
-
-    SECTION("issue #5650 - stack overflow converting between specializations")
-    {
-        const std::vector<std::string> patterns = {"[", "{", "[{"};
-
-        SECTION("json to ordered_json")
-        {
-            for (const auto& pattern : patterns)
-            {
-                CAPTURE(pattern)
-                const std::string text = nested_text(depth, pattern);
-                const json j = json::parse(text);
-
-                const nlohmann::ordered_json converted = j;
-                CHECK(converted.dump() == text);
-            }
-        }
-
-        SECTION("ordered_json to json")
-        {
-            for (const auto& pattern : patterns)
-            {
-                CAPTURE(pattern)
-                const std::string text = nested_text(depth, pattern);
-                const nlohmann::ordered_json o = nlohmann::ordered_json::parse(text);
-
-                const json converted = o;
-                CHECK(converted.dump() == text);
-            }
-        }
-
-        SECTION("get<ordered_json>()")
-        {
-            for (const auto& pattern : patterns)
-            {
-                CAPTURE(pattern)
-                const std::string text = nested_text(depth, pattern);
-                const json j = json::parse(text);
-
-                CHECK(j.get<nlohmann::ordered_json>().dump() == text);
-            }
-        }
-
-        SECTION("depths around the bound of the recursive descent")
-        {
-            for (std::size_t d = 1; d <= 300; ++d)
-            {
-                CAPTURE(d)
-                for (const auto& pattern : patterns)
-                {
-                    CAPTURE(pattern)
-                    const std::string text = nested_text(d, pattern);
-                    const json j = json::parse(text);
-
-                    const nlohmann::ordered_json converted = j;
-                    CHECK(converted.dump() == text);
-                    const json back = converted;
-                    CHECK(back.dump() == text);
-                }
-            }
-        }
-
-        SECTION("values below the bound are converted as values above it")
-        {
-            // Bury a value below the bound, where it is converted without the
-            // call stack, and compare it with the same value converted on its
-            // own by the containers' range constructors. Its objects have
-            // members that the two object types enumerate in different orders.
-            const auto bury = [](nlohmann::ordered_json value)
-            {
-                for (std::size_t i = 0; i < 200; ++i)
-                {
-                    value = nlohmann::ordered_json::array({std::move(value)});
-                }
-                return value;
-            };
-            const auto dig = [](const json & value)
-            {
-                const json* current = &value;
-                for (std::size_t i = 0; i < 200; ++i)
-                {
-                    current = &current->at(0);
-                }
-                return current;
-            };
-
-            nlohmann::ordered_json value = nlohmann::ordered_json::object();
-            value["z"] = {1, -2, 3U, 4.5, true, nullptr, "six", nlohmann::ordered_json::binary({7, 8}, 9),
-                          nlohmann::ordered_json::binary({10}), nlohmann::ordered_json::array(), nlohmann::ordered_json::object()
-                         };
-            value["y"] = {{"x", {{"w", 1}, {"v", 2}}}, {"u", {3, {{"t", 4}, {"s", 5}}}}};
-            value["r"] = nlohmann::ordered_json::array({nlohmann::ordered_json(nlohmann::ordered_json::value_t::discarded)});
-
-            const json converted_above = value;
-            const json buried = bury(value);
-            const json& converted_below = *dig(buried);
-
-            CHECK(converted_below.dump() == converted_above.dump());
-            CHECK(converted_below.at("z").at(7).get_binary().subtype() == 9);
-            CHECK_FALSE(converted_below.at("z").at(8).get_binary().has_subtype());
-            CHECK(converted_below.at("r").at(0).is_discarded());
-
-            // a discarded value is never equal to anything, so compare the rest
-            value.erase("r");
-            const json without_discarded_above = value;
-            const json without_discarded_buried = bury(value);
-            CHECK(*dig(without_discarded_buried) == without_discarded_above);
-        }
-    }
 }
-
-namespace
-{
-json nested_array(const std::size_t depth, json leaf)
-{
-    json j = std::move(leaf);
-    for (std::size_t i = 0; i < depth; ++i)
-    {
-        json a = json::array();
-        a.push_back(std::move(j));
-        j = std::move(a);
-    }
-    return j;
-}
-
-json nested_object(const std::size_t depth, json leaf)
-{
-    json j = std::move(leaf);
-    for (std::size_t i = 0; i < depth; ++i)
-    {
-        json o = json::object();
-        o["k"] = std::move(j);
-        j = std::move(o);
-    }
-    return j;
-}
-} // namespace
-
-TEST_CASE("issue #5392 - binary writers on deeply nested values")
-{
-    // 200 is past the point where the writers stop recursing, and still
-    // shallow enough that from_* and operator== (which still recurse) are fine.
-    const json deep_array = nested_array(200, json(0));
-    const json deep_object = nested_object(200, json("x"));
-    const json empty_array = nested_array(200, json::array());
-    const json empty_object = nested_object(200, json::object());
-    const json mixed = nested_object(80, nested_array(80, json(true)));
-
-    SECTION("roundtrip past the recursion bound")
-    {
-        CHECK(json::from_cbor(json::to_cbor(deep_array)) == deep_array);
-        CHECK(json::from_msgpack(json::to_msgpack(deep_array)) == deep_array);
-        CHECK(json::from_ubjson(json::to_ubjson(deep_array)) == deep_array);
-        CHECK(json::from_ubjson(json::to_ubjson(deep_array, true, false)) == deep_array);
-        CHECK(json::from_ubjson(json::to_ubjson(deep_array, true, true)) == deep_array);
-        CHECK(json::from_bjdata(json::to_bjdata(deep_array)) == deep_array);
-        CHECK(json::from_bon8(json::to_bon8(deep_array)) == deep_array);
-
-        CHECK(json::from_cbor(json::to_cbor(deep_object)) == deep_object);
-        CHECK(json::from_msgpack(json::to_msgpack(deep_object)) == deep_object);
-        CHECK(json::from_ubjson(json::to_ubjson(deep_object)) == deep_object);
-        CHECK(json::from_ubjson(json::to_ubjson(deep_object, true, true)) == deep_object);
-        CHECK(json::from_bjdata(json::to_bjdata(deep_object)) == deep_object);
-        CHECK(json::from_bon8(json::to_bon8(deep_object)) == deep_object);
-
-        CHECK(json::from_cbor(json::to_cbor(empty_array)) == empty_array);
-        CHECK(json::from_msgpack(json::to_msgpack(empty_array)) == empty_array);
-        CHECK(json::from_ubjson(json::to_ubjson(empty_array)) == empty_array);
-        CHECK(json::from_ubjson(json::to_ubjson(empty_array, true, true)) == empty_array);
-        CHECK(json::from_bon8(json::to_bon8(empty_array)) == empty_array);
-
-        CHECK(json::from_cbor(json::to_cbor(empty_object)) == empty_object);
-        CHECK(json::from_msgpack(json::to_msgpack(empty_object)) == empty_object);
-        CHECK(json::from_ubjson(json::to_ubjson(empty_object)) == empty_object);
-        CHECK(json::from_bon8(json::to_bon8(empty_object)) == empty_object);
-
-        CHECK(json::from_cbor(json::to_cbor(mixed)) == mixed);
-        CHECK(json::from_msgpack(json::to_msgpack(mixed)) == mixed);
-        CHECK(json::from_ubjson(json::to_ubjson(mixed)) == mixed);
-        CHECK(json::from_bjdata(json::to_bjdata(mixed)) == mixed);
-        CHECK(json::from_bon8(json::to_bon8(mixed)) == mixed);
-    }
-
-    SECTION("the two ways of writing a value meet at the bound")
-    {
-        for (std::size_t depth = 120; depth <= 140; ++depth)
-        {
-            CAPTURE(depth)
-
-            const json array = nested_array(depth, json(7));
-            CHECK(json::from_cbor(json::to_cbor(array)) == array);
-            CHECK(json::from_msgpack(json::to_msgpack(array)) == array);
-            CHECK(json::from_ubjson(json::to_ubjson(array, true, true)) == array);
-            CHECK(json::from_bon8(json::to_bon8(array)) == array);
-
-            const json object = nested_object(depth, json(7));
-            CHECK(json::from_cbor(json::to_cbor(object)) == object);
-            CHECK(json::from_msgpack(json::to_msgpack(object)) == object);
-            CHECK(json::from_bjdata(json::to_bjdata(object)) == object);
-            CHECK(json::from_bon8(json::to_bon8(object)) == object);
-        }
-    }
-
-    SECTION("a BJData ndarray below the bound is still an ndarray")
-    {
-        const json ndarray = json({{"_ArrayType_", "uint8"}, {"_ArraySize_", {2, 3}}, {"_ArrayData_", {1, 2, 3, 4, 5, 6}}});
-        const json invalid = json({{"_ArrayType_", "nope"}, {"_ArraySize_", {1}}, {"_ArrayData_", {1}}});
-
-        const json deep_ndarray = nested_array(140, ndarray);
-        const json deep_invalid = nested_array(140, invalid);
-
-        CHECK(json::from_bjdata(json::to_bjdata(deep_ndarray)) == deep_ndarray);
-        CHECK(json::from_bjdata(json::to_bjdata(deep_invalid)) == deep_invalid);
-        CHECK(json::from_bjdata(json::to_bjdata(ndarray)) == ndarray);
-    }
-
-    SECTION("byte-exact across the switch-over")
-    {
-        // nested one-element arrays around the recursion bound: the exact
-        // bytes a writer produces do not depend on whether it stayed on the
-        // call stack or moved to the heap one partway through
-        for (const std::size_t depth :
-                {
-                    nlohmann::detail::recursion_depth_limit() - 1, nlohmann::detail::recursion_depth_limit(),
-                    nlohmann::detail::recursion_depth_limit() + 1, nlohmann::detail::recursion_depth_limit() + 2
-                })
-        {
-            CAPTURE(depth)
-            const json array = nested_array(depth, json(0));
-
-            std::vector<std::uint8_t> expected_cbor(depth, 0x81);
-            expected_cbor.push_back(0x00);
-            CHECK(json::to_cbor(array) == expected_cbor);
-
-            std::vector<std::uint8_t> expected_msgpack(depth, 0x91);
-            expected_msgpack.push_back(0x00);
-            CHECK(json::to_msgpack(array) == expected_msgpack);
-
-            std::string expected_ubjson(depth, '[');
-            expected_ubjson += "i";
-            expected_ubjson += '\0';
-            expected_ubjson.append(depth, ']');
-            const auto packed_ubjson = json::to_ubjson(array);
-            CHECK(std::string(packed_ubjson.begin(), packed_ubjson.end()) == expected_ubjson);
-
-            std::vector<std::uint8_t> expected_bon8(depth, 0x81);
-            expected_bon8.push_back(0x90);
-            CHECK(json::to_bon8(array) == expected_bon8);
-        }
-    }
-
-    SECTION("a deep object, and a BJData ndarray, past the recursion bound")
-    {
-        const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 50;
-
-        const json object = nested_object(depth, json(42));
-        CHECK(json::from_cbor(json::to_cbor(object)) == object);
-        CHECK(json::from_msgpack(json::to_msgpack(object)) == object);
-        CHECK(json::from_ubjson(json::to_ubjson(object, true, true)) == object);
-        CHECK(json::from_bjdata(json::to_bjdata(object)) == object);
-        CHECK(json::from_bon8(json::to_bon8(object)) == object);
-
-        const json ndarray = json({{"_ArrayType_", "uint8"}, {"_ArraySize_", {2, 3}}, {"_ArrayData_", {1, 2, 3, 4, 5, 6}}});
-        const json deep_ndarray = nested_array(depth, ndarray);
-        CHECK(json::from_bjdata(json::to_bjdata(deep_ndarray)) == deep_ndarray);
-    }
-
-    SECTION("a discarded value past the recursion bound still throws type_error.321")
-    {
-        const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 50;
-        const json discarded_leaf(json::value_t::discarded);
-        const json deep_discarded = nested_array(depth, discarded_leaf);
-
-        // with diagnostics, the message names the path to the discarded leaf
-#if JSON_DIAGNOSTICS
-        std::string path;
-        for (std::size_t i = 0; i < depth; ++i)
-        {
-            path += "/0";
-        }
-        const std::string prefix = "[json.exception.type_error.321] (" + path + ") ";
-#else
-        const std::string prefix = "[json.exception.type_error.321] ";
-#endif
-
-        CHECK_THROWS_WITH_AS(json::to_cbor(deep_discarded), (prefix + "cannot serialize discarded value to CBOR").c_str(), json::type_error);
-        CHECK_THROWS_WITH_AS(json::to_msgpack(deep_discarded), (prefix + "cannot serialize discarded value to MessagePack").c_str(), json::type_error);
-        CHECK_THROWS_WITH_AS(json::to_ubjson(deep_discarded), (prefix + "cannot serialize discarded value to UBJSON").c_str(), json::type_error);
-        CHECK_THROWS_WITH_AS(json::to_bjdata(deep_discarded), (prefix + "cannot serialize discarded value to BJData").c_str(), json::type_error);
-    }
-
-    SECTION("BON8 past the recursion bound: discarded values and errors")
-    {
-        const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 50;
-
-        // BON8 rejects a discarded value (type_error.321), deep or not
-        const json deep_discarded = nested_array(depth, json(json::value_t::discarded));
-        CHECK_THROWS_AS(json::to_bon8(deep_discarded), json::type_error);
-
-        // errors are thrown from below the bound as from above it
-        const json deep_invalid_string = nested_array(depth, json(std::string("\x80")));
-        CHECK_THROWS_AS(json::to_bon8(deep_invalid_string), json::type_error);
-
-        json deep_invalid_key = json::object();
-        deep_invalid_key[std::string("\x80")] = 1;
-        deep_invalid_key = nested_object(depth, deep_invalid_key);
-        CHECK_THROWS_AS(json::to_bon8(deep_invalid_key), json::type_error);
-
-        const json deep_too_large = nested_array(depth, json(9223372036854775808u));
-        CHECK_THROWS_AS(json::to_bon8(deep_too_large), json::out_of_range);
-    }
-
-    SECTION("does not overflow the C++ stack")
-    {
-        const std::size_t depth = 100000;
-        const json j = json::parse(std::string(depth, '[') + "0" + std::string(depth, ']'));
-
-        std::vector<std::uint8_t> packed;
-        CHECK_NOTHROW(packed = json::to_cbor(j));
-        CHECK(json::from_cbor(packed) == j);
-
-        CHECK_NOTHROW(packed = json::to_msgpack(j));
-        CHECK(json::from_msgpack(packed) == j);
-
-        CHECK_NOTHROW(packed = json::to_ubjson(j));
-        CHECK(json::from_ubjson(packed) == j);
-
-        CHECK_NOTHROW(packed = json::to_ubjson(j, true, false));
-        CHECK(json::from_ubjson(packed) == j);
-
-        CHECK_NOTHROW(packed = json::to_bjdata(j));
-        CHECK(json::from_bjdata(packed) == j);
-
-        CHECK_NOTHROW(packed = json::to_bon8(j));
-        CHECK(json::from_bon8(packed) == j);
-    }
-
-    SECTION("BON8 containers with more than four elements past the recursion bound")
-    {
-        // such containers are closed with 0xFE, which the iterative writer
-        // must emit when it leaves them; strings next to each other must
-        // still be separated with 0xFF
-        const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 50;
-        json wide_array = json::array({1, "a", "b", json::array(), 5});
-        json wide_object = json({{"k1", "v"}, {"k2", 2}, {"k3", ""}, {"k4", json::object()}, {"k5", nullptr}});
-        for (std::size_t i = 0; i < depth; ++i)
-        {
-            wide_array = json::array({"s", wide_array, "t", wide_object, true});
-            wide_object = json({{"a", wide_object}, {"b", "x"}, {"c", "y"}, {"d", wide_array.size()}, {"e", "z"}});
-        }
-
-        CHECK(json::from_bon8(json::to_bon8(wide_array)) == wide_array);
-        CHECK(json::from_bon8(json::to_bon8(wide_object)) == wide_object);
-    }
-
-    SECTION("regression test for https://issues.oss-fuzz.com/issues/566583014")
-    {
-        // 200000 nested one-element CBOR arrays, the innermost holding null;
-        // round-tripping this used to recurse once per level on the way back
-        // out through to_cbor(), deep enough to overflow the stack
-        std::vector<std::uint8_t> v(200000, 0x81);
-        v.push_back(0xf6);
-        const json j = json::from_cbor(v);
-        CHECK(json::to_cbor(j) == v);
-
-        // the MessagePack analogue: fixarray of 1 nesting down to nil
-        std::vector<std::uint8_t> v_msgpack(200000, 0x91);
-        v_msgpack.push_back(0xc0);
-        const json j_msgpack = json::from_msgpack(v_msgpack);
-        CHECK(json::to_msgpack(j_msgpack) == v_msgpack);
-    }
-
-    SECTION("regression test for https://issues.oss-fuzz.com/issues/572238015")
-    {
-        // the BON8 analogue: 200000 nested one-element arrays down to null
-        std::vector<std::uint8_t> v(200000, 0x81);
-        v.push_back(0xFA);
-        const json j = json::from_bon8(v);
-        CHECK(json::to_bon8(j) == v);
-    }
-}
-

tests/src/unit-large_json_binary_writers.cpp

@@ -0,0 +1,294 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <utility>
+#include <vector>
+
+// split from unit-large_json.cpp so that both run in parallel and stay below
+// the ctest timeout under Valgrind
+
+namespace
+{
+json nested_array(const std::size_t depth, json leaf)
+{
+    json j = std::move(leaf);
+    for (std::size_t i = 0; i < depth; ++i)
+    {
+        json a = json::array();
+        a.push_back(std::move(j));
+        j = std::move(a);
+    }
+    return j;
+}
+
+json nested_object(const std::size_t depth, json leaf)
+{
+    json j = std::move(leaf);
+    for (std::size_t i = 0; i < depth; ++i)
+    {
+        json o = json::object();
+        o["k"] = std::move(j);
+        j = std::move(o);
+    }
+    return j;
+}
+} // namespace
+
+TEST_CASE("issue #5392 - binary writers on deeply nested values")
+{
+    // 200 is past the point where the writers stop recursing, and still
+    // shallow enough that from_* and operator== (which still recurse) are fine.
+    const json deep_array = nested_array(200, json(0));
+    const json deep_object = nested_object(200, json("x"));
+    const json empty_array = nested_array(200, json::array());
+    const json empty_object = nested_object(200, json::object());
+    const json mixed = nested_object(80, nested_array(80, json(true)));
+
+    SECTION("roundtrip past the recursion bound")
+    {
+        CHECK(json::from_cbor(json::to_cbor(deep_array)) == deep_array);
+        CHECK(json::from_msgpack(json::to_msgpack(deep_array)) == deep_array);
+        CHECK(json::from_ubjson(json::to_ubjson(deep_array)) == deep_array);
+        CHECK(json::from_ubjson(json::to_ubjson(deep_array, true, false)) == deep_array);
+        CHECK(json::from_ubjson(json::to_ubjson(deep_array, true, true)) == deep_array);
+        CHECK(json::from_bjdata(json::to_bjdata(deep_array)) == deep_array);
+        CHECK(json::from_bon8(json::to_bon8(deep_array)) == deep_array);
+
+        CHECK(json::from_cbor(json::to_cbor(deep_object)) == deep_object);
+        CHECK(json::from_msgpack(json::to_msgpack(deep_object)) == deep_object);
+        CHECK(json::from_ubjson(json::to_ubjson(deep_object)) == deep_object);
+        CHECK(json::from_ubjson(json::to_ubjson(deep_object, true, true)) == deep_object);
+        CHECK(json::from_bjdata(json::to_bjdata(deep_object)) == deep_object);
+        CHECK(json::from_bon8(json::to_bon8(deep_object)) == deep_object);
+
+        CHECK(json::from_cbor(json::to_cbor(empty_array)) == empty_array);
+        CHECK(json::from_msgpack(json::to_msgpack(empty_array)) == empty_array);
+        CHECK(json::from_ubjson(json::to_ubjson(empty_array)) == empty_array);
+        CHECK(json::from_ubjson(json::to_ubjson(empty_array, true, true)) == empty_array);
+        CHECK(json::from_bon8(json::to_bon8(empty_array)) == empty_array);
+
+        CHECK(json::from_cbor(json::to_cbor(empty_object)) == empty_object);
+        CHECK(json::from_msgpack(json::to_msgpack(empty_object)) == empty_object);
+        CHECK(json::from_ubjson(json::to_ubjson(empty_object)) == empty_object);
+        CHECK(json::from_bon8(json::to_bon8(empty_object)) == empty_object);
+
+        CHECK(json::from_cbor(json::to_cbor(mixed)) == mixed);
+        CHECK(json::from_msgpack(json::to_msgpack(mixed)) == mixed);
+        CHECK(json::from_ubjson(json::to_ubjson(mixed)) == mixed);
+        CHECK(json::from_bjdata(json::to_bjdata(mixed)) == mixed);
+        CHECK(json::from_bon8(json::to_bon8(mixed)) == mixed);
+    }
+
+    SECTION("the two ways of writing a value meet at the bound")
+    {
+        for (std::size_t depth = 120; depth <= 140; ++depth)
+        {
+            CAPTURE(depth)
+
+            const json array = nested_array(depth, json(7));
+            CHECK(json::from_cbor(json::to_cbor(array)) == array);
+            CHECK(json::from_msgpack(json::to_msgpack(array)) == array);
+            CHECK(json::from_ubjson(json::to_ubjson(array, true, true)) == array);
+            CHECK(json::from_bon8(json::to_bon8(array)) == array);
+
+            const json object = nested_object(depth, json(7));
+            CHECK(json::from_cbor(json::to_cbor(object)) == object);
+            CHECK(json::from_msgpack(json::to_msgpack(object)) == object);
+            CHECK(json::from_bjdata(json::to_bjdata(object)) == object);
+            CHECK(json::from_bon8(json::to_bon8(object)) == object);
+        }
+    }
+
+    SECTION("a BJData ndarray below the bound is still an ndarray")
+    {
+        const json ndarray = json({{"_ArrayType_", "uint8"}, {"_ArraySize_", {2, 3}}, {"_ArrayData_", {1, 2, 3, 4, 5, 6}}});
+        const json invalid = json({{"_ArrayType_", "nope"}, {"_ArraySize_", {1}}, {"_ArrayData_", {1}}});
+
+        const json deep_ndarray = nested_array(140, ndarray);
+        const json deep_invalid = nested_array(140, invalid);
+
+        CHECK(json::from_bjdata(json::to_bjdata(deep_ndarray)) == deep_ndarray);
+        CHECK(json::from_bjdata(json::to_bjdata(deep_invalid)) == deep_invalid);
+        CHECK(json::from_bjdata(json::to_bjdata(ndarray)) == ndarray);
+    }
+
+    SECTION("byte-exact across the switch-over")
+    {
+        // nested one-element arrays around the recursion bound: the exact
+        // bytes a writer produces do not depend on whether it stayed on the
+        // call stack or moved to the heap one partway through
+        for (const std::size_t depth :
+                {
+                    nlohmann::detail::recursion_depth_limit() - 1, nlohmann::detail::recursion_depth_limit(),
+                    nlohmann::detail::recursion_depth_limit() + 1, nlohmann::detail::recursion_depth_limit() + 2
+                })
+        {
+            CAPTURE(depth)
+            const json array = nested_array(depth, json(0));
+
+            std::vector<std::uint8_t> expected_cbor(depth, 0x81);
+            expected_cbor.push_back(0x00);
+            CHECK(json::to_cbor(array) == expected_cbor);
+
+            std::vector<std::uint8_t> expected_msgpack(depth, 0x91);
+            expected_msgpack.push_back(0x00);
+            CHECK(json::to_msgpack(array) == expected_msgpack);
+
+            std::string expected_ubjson(depth, '[');
+            expected_ubjson += "i";
+            expected_ubjson += '\0';
+            expected_ubjson.append(depth, ']');
+            const auto packed_ubjson = json::to_ubjson(array);
+            CHECK(std::string(packed_ubjson.begin(), packed_ubjson.end()) == expected_ubjson);
+
+            std::vector<std::uint8_t> expected_bon8(depth, 0x81);
+            expected_bon8.push_back(0x90);
+            CHECK(json::to_bon8(array) == expected_bon8);
+        }
+    }
+
+    SECTION("a deep object, and a BJData ndarray, past the recursion bound")
+    {
+        const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 50;
+
+        const json object = nested_object(depth, json(42));
+        CHECK(json::from_cbor(json::to_cbor(object)) == object);
+        CHECK(json::from_msgpack(json::to_msgpack(object)) == object);
+        CHECK(json::from_ubjson(json::to_ubjson(object, true, true)) == object);
+        CHECK(json::from_bjdata(json::to_bjdata(object)) == object);
+        CHECK(json::from_bon8(json::to_bon8(object)) == object);
+
+        const json ndarray = json({{"_ArrayType_", "uint8"}, {"_ArraySize_", {2, 3}}, {"_ArrayData_", {1, 2, 3, 4, 5, 6}}});
+        const json deep_ndarray = nested_array(depth, ndarray);
+        CHECK(json::from_bjdata(json::to_bjdata(deep_ndarray)) == deep_ndarray);
+    }
+
+    SECTION("a discarded value past the recursion bound still throws type_error.321")
+    {
+        const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 50;
+        const json discarded_leaf(json::value_t::discarded);
+        const json deep_discarded = nested_array(depth, discarded_leaf);
+
+        // with diagnostics, the message names the path to the discarded leaf
+#if JSON_DIAGNOSTICS
+        std::string path;
+        for (std::size_t i = 0; i < depth; ++i)
+        {
+            path += "/0";
+        }
+        const std::string prefix = "[json.exception.type_error.321] (" + path + ") ";
+#else
+        const std::string prefix = "[json.exception.type_error.321] ";
+#endif
+
+        CHECK_THROWS_WITH_AS(json::to_cbor(deep_discarded), (prefix + "cannot serialize discarded value to CBOR").c_str(), json::type_error);
+        CHECK_THROWS_WITH_AS(json::to_msgpack(deep_discarded), (prefix + "cannot serialize discarded value to MessagePack").c_str(), json::type_error);
+        CHECK_THROWS_WITH_AS(json::to_ubjson(deep_discarded), (prefix + "cannot serialize discarded value to UBJSON").c_str(), json::type_error);
+        CHECK_THROWS_WITH_AS(json::to_bjdata(deep_discarded), (prefix + "cannot serialize discarded value to BJData").c_str(), json::type_error);
+    }
+
+    SECTION("BON8 past the recursion bound: discarded values and errors")
+    {
+        const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 50;
+
+        // BON8 rejects a discarded value (type_error.321), deep or not
+        const json deep_discarded = nested_array(depth, json(json::value_t::discarded));
+        CHECK_THROWS_AS(json::to_bon8(deep_discarded), json::type_error);
+
+        // errors are thrown from below the bound as from above it
+        const json deep_invalid_string = nested_array(depth, json(std::string("\x80")));
+        CHECK_THROWS_AS(json::to_bon8(deep_invalid_string), json::type_error);
+
+        json deep_invalid_key = json::object();
+        deep_invalid_key[std::string("\x80")] = 1;
+        deep_invalid_key = nested_object(depth, deep_invalid_key);
+        CHECK_THROWS_AS(json::to_bon8(deep_invalid_key), json::type_error);
+
+        const json deep_too_large = nested_array(depth, json(9223372036854775808u));
+        CHECK_THROWS_AS(json::to_bon8(deep_too_large), json::out_of_range);
+    }
+
+    SECTION("does not overflow the C++ stack")
+    {
+        const std::size_t depth = 100000;
+        const json j = json::parse(std::string(depth, '[') + "0" + std::string(depth, ']'));
+
+        std::vector<std::uint8_t> packed;
+        CHECK_NOTHROW(packed = json::to_cbor(j));
+        CHECK(json::from_cbor(packed) == j);
+
+        CHECK_NOTHROW(packed = json::to_msgpack(j));
+        CHECK(json::from_msgpack(packed) == j);
+
+        CHECK_NOTHROW(packed = json::to_ubjson(j));
+        CHECK(json::from_ubjson(packed) == j);
+
+        CHECK_NOTHROW(packed = json::to_ubjson(j, true, false));
+        CHECK(json::from_ubjson(packed) == j);
+
+        CHECK_NOTHROW(packed = json::to_bjdata(j));
+        CHECK(json::from_bjdata(packed) == j);
+
+        CHECK_NOTHROW(packed = json::to_bon8(j));
+        CHECK(json::from_bon8(packed) == j);
+    }
+
+    SECTION("BON8 containers with more than four elements past the recursion bound")
+    {
+        // such containers are closed with 0xFE, which the iterative writer
+        // must emit when it leaves them; strings next to each other must
+        // still be separated with 0xFF
+        const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 50;
+        json wide_array = json::array({1, "a", "b", json::array(), 5});
+        json wide_object = json({{"k1", "v"}, {"k2", 2}, {"k3", ""}, {"k4", json::object()}, {"k5", nullptr}});
+        for (std::size_t i = 0; i < depth; ++i)
+        {
+            wide_array = json::array({"s", wide_array, "t", wide_object, true});
+            wide_object = json({{"a", wide_object}, {"b", "x"}, {"c", "y"}, {"d", wide_array.size()}, {"e", "z"}});
+        }
+
+        CHECK(json::from_bon8(json::to_bon8(wide_array)) == wide_array);
+        CHECK(json::from_bon8(json::to_bon8(wide_object)) == wide_object);
+    }
+
+    SECTION("regression test for https://issues.oss-fuzz.com/issues/566583014")
+    {
+        // 200000 nested one-element CBOR arrays, the innermost holding null;
+        // round-tripping this used to recurse once per level on the way back
+        // out through to_cbor(), deep enough to overflow the stack
+        std::vector<std::uint8_t> v(200000, 0x81);
+        v.push_back(0xf6);
+        const json j = json::from_cbor(v);
+        CHECK(json::to_cbor(j) == v);
+
+        // the MessagePack analogue: fixarray of 1 nesting down to nil
+        std::vector<std::uint8_t> v_msgpack(200000, 0x91);
+        v_msgpack.push_back(0xc0);
+        const json j_msgpack = json::from_msgpack(v_msgpack);
+        CHECK(json::to_msgpack(j_msgpack) == v_msgpack);
+    }
+
+    SECTION("regression test for https://issues.oss-fuzz.com/issues/572238015")
+    {
+        // the BON8 analogue: 200000 nested one-element arrays down to null
+        std::vector<std::uint8_t> v(200000, 0x81);
+        v.push_back(0xFA);
+        const json j = json::from_bon8(v);
+        CHECK(json::to_bon8(j) == v);
+    }
+}
+

tests/src/unit-large_json_conversions.cpp

@@ -0,0 +1,156 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <cstddef>
+#include <string>
+#include <utility>
+#include <vector>
+
+// split from unit-large_json.cpp so that both run in parallel and stay below
+// the ctest timeout under Valgrind
+
+namespace
+{
+
+// The text of a value nested depth levels deep around the number 0. Level i is
+// an array if pattern[i % pattern.size()] is '[', and otherwise an object with
+// the single member "a", which every object type enumerates in the same order.
+std::string nested_text(std::size_t depth, const std::string& pattern)
+{
+    std::string text;
+    std::string closing;
+    for (std::size_t i = 0; i < depth; ++i)
+    {
+        const bool array = pattern[i % pattern.size()] == '[';
+        text += array ? "[" : "{\"a\":";
+        closing += array ? ']' : '}';
+    }
+    text += '0';
+    text.append(closing.rbegin(), closing.rend());
+    return text;
+}
+
+} // namespace
+
+TEST_CASE("issue #5650 - stack overflow converting between specializations")
+{
+    // deep enough to exhaust the call stack, but small enough to stay cheap:
+    // parsing is iterative, so building the values below costs little
+    const std::size_t depth = 100000;
+
+    const std::vector<std::string> patterns = {"[", "{", "[{"};
+
+    SECTION("json to ordered_json")
+    {
+        for (const auto& pattern : patterns)
+        {
+            CAPTURE(pattern)
+            const std::string text = nested_text(depth, pattern);
+            const json j = json::parse(text);
+
+            const nlohmann::ordered_json converted = j;
+            CHECK(converted.dump() == text);
+        }
+    }
+
+    SECTION("ordered_json to json")
+    {
+        for (const auto& pattern : patterns)
+        {
+            CAPTURE(pattern)
+            const std::string text = nested_text(depth, pattern);
+            const nlohmann::ordered_json o = nlohmann::ordered_json::parse(text);
+
+            const json converted = o;
+            CHECK(converted.dump() == text);
+        }
+    }
+
+    SECTION("get<ordered_json>()")
+    {
+        for (const auto& pattern : patterns)
+        {
+            CAPTURE(pattern)
+            const std::string text = nested_text(depth, pattern);
+            const json j = json::parse(text);
+
+            CHECK(j.get<nlohmann::ordered_json>().dump() == text);
+        }
+    }
+
+    SECTION("depths around the bound of the recursive descent")
+    {
+        for (std::size_t d = 1; d <= 300; ++d)
+        {
+            CAPTURE(d)
+            for (const auto& pattern : patterns)
+            {
+                CAPTURE(pattern)
+                const std::string text = nested_text(d, pattern);
+                const json j = json::parse(text);
+
+                const nlohmann::ordered_json converted = j;
+                CHECK(converted.dump() == text);
+                const json back = converted;
+                CHECK(back.dump() == text);
+            }
+        }
+    }
+
+    SECTION("values below the bound are converted as values above it")
+    {
+        // Bury a value below the bound, where it is converted without the
+        // call stack, and compare it with the same value converted on its
+        // own by the containers' range constructors. Its objects have
+        // members that the two object types enumerate in different orders.
+        const auto bury = [](nlohmann::ordered_json value)
+        {
+            for (std::size_t i = 0; i < 200; ++i)
+            {
+                value = nlohmann::ordered_json::array({std::move(value)});
+            }
+            return value;
+        };
+        const auto dig = [](const json & value)
+        {
+            const json* current = &value;
+            for (std::size_t i = 0; i < 200; ++i)
+            {
+                current = &current->at(0);
+            }
+            return current;
+        };
+
+        nlohmann::ordered_json value = nlohmann::ordered_json::object();
+        value["z"] = {1, -2, 3U, 4.5, true, nullptr, "six", nlohmann::ordered_json::binary({7, 8}, 9),
+                      nlohmann::ordered_json::binary({10}), nlohmann::ordered_json::array(), nlohmann::ordered_json::object()
+                     };
+        value["y"] = {{"x", {{"w", 1}, {"v", 2}}}, {"u", {3, {{"t", 4}, {"s", 5}}}}};
+        value["r"] = nlohmann::ordered_json::array({nlohmann::ordered_json(nlohmann::ordered_json::value_t::discarded)});
+
+        const json converted_above = value;
+        const json buried = bury(value);
+        const json& converted_below = *dig(buried);
+
+        CHECK(converted_below.dump() == converted_above.dump());
+        CHECK(converted_below.at("z").at(7).get_binary().subtype() == 9);
+        CHECK_FALSE(converted_below.at("z").at(8).get_binary().has_subtype());
+        CHECK(converted_below.at("r").at(0).is_discarded());
+
+        // a discarded value is never equal to anything, so compare the rest
+        value.erase("r");
+        const json without_discarded_above = value;
+        const json without_discarded_buried = bury(value);
+        CHECK(*dig(without_discarded_buried) == without_discarded_above);
+    }
+}

tests/src/unit-qt_keywords.cpp

@@ -0,0 +1,67 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+// Qt defines its keywords as macros (see qtmetamacros.h and qforeach.h) unless
+// QT_NO_KEYWORDS is defined, and it is common to include Qt headers before this
+// library; it must therefore not use these words as identifiers (see #5865)
+#define slots
+#define signals public
+#define emit
+#define Q_FOREACH(variable, container) for (variable : container) // NOLINT(bugprone-macro-parentheses): variable is a declaration, as in Qt
+#define foreach Q_FOREACH
+#define forever for (;;)
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+TEST_CASE("Qt keyword macros")
+{
+    SECTION("parse and dump")
+    {
+        const json j = json::parse(R"({"a": [1, 2.5, "x", null, true]})");
+        CHECK(j.dump() == R"({"a":[1,2.5,"x",null,true]})");
+    }
+
+    SECTION("flatten and unflatten")
+    {
+        const json j = {{"a", {{"b", {1, 2}}, {"c", "d"}}}, {"e", nullptr}};
+        CHECK(j.flatten().unflatten() == j);
+    }
+
+    SECTION("JSON pointer")
+    {
+        json j = {{"a", {{"b", {1, 2}}}}};
+        CHECK(j.at(json::json_pointer("/a/b/1")) == 2);
+        j[json::json_pointer("/a/c")] = 3;
+        CHECK(j.contains(json::json_pointer("/a/c")));
+    }
+
+    SECTION("binary formats")
+    {
+        const json j = {{"a", {1, 2, 3}}, {"b", "c"}};
+        CHECK(json::from_cbor(json::to_cbor(j)) == j);
+        CHECK(json::from_msgpack(json::to_msgpack(j)) == j);
+        CHECK(json::from_ubjson(json::to_ubjson(j)) == j);
+        CHECK(json::from_bjdata(json::to_bjdata(j)) == j);
+        CHECK(json::from_bson(json::to_bson(j)) == j);
+    }
+
+    SECTION("patch and diff")
+    {
+        const json source = {{"a", 1}, {"b", {1, 2}}};
+        const json target = {{"a", 2}, {"c", "d"}};
+        CHECK(source.patch(json::diff(source, target)) == target);
+    }
+}
+
+// testing for the macros also keeps -Wunused-macros from rejecting them
+#if !defined(slots) || !defined(signals) || !defined(emit) || !defined(Q_FOREACH) || !defined(foreach) || !defined(forever)
+    #error "the Qt keyword macros must stay defined for the tests above"
+#endif

tests/src/unit-serialization.cpp

@@ -1374,7 +1374,13 @@ void check_dump_against_reference(const std::string& s, const bool with_strict =
     };
     for (const auto error_handler : error_handlers)
     {
+#if defined(JSON_NOEXCEPTION)
+        // a strict dump of invalid UTF-8 calls std::abort() instead of throwing
+        static_cast<void>(with_strict);
+        if (error_handler == json::error_handler_t::strict)
+#else
         if (!with_strict && error_handler == json::error_handler_t::strict)
+#endif
         {
             continue;
         }
@@ -1429,7 +1435,7 @@ TEST_CASE("invalid UTF-8 at every position is handled like the reference")
         "\xF4\x90\x80\x80",
         // sequences cut short by ASCII, a control character, a quote, a
         // backslash, DEL, or the lead byte of a well-formed character
-        "\xC3" "a", "\xE2\x82" "\n", "\xE2\x82\"", "\xF0\x9F\x98\\", "\xC3\x7F", "\xC3\xC3\xA4", "\xE2\xF0\x9F\x98\x80",
+        "\xC3" "a", "\xE2\x82" "\n", "\xE2\x82\"", "\xF0\x9F\x98\\", "\xC3\x7F", "\xC3\xC3\xA4", "\xE2\xF0\x9F\x98\x80", // NOLINT(bugprone-suspicious-missing-comma): "\xC3" "a" ends the hex escape
         // truncated sequences
         "\xC3", "\xE2\x82", "\xF0\x9F\x98"
     };
@@ -1489,7 +1495,7 @@ TEST_CASE("invalid UTF-8 at every position is handled like the reference")
                 {
                     for (const auto& pattern : patterns)
                     {
-                        check_dump_against_reference(make_string(filler, pos, pattern, length - pos), bytes <= (filler.size() == 1 ? 17 : 8));
+                        check_dump_against_reference(make_string(filler, pos, pattern, length - pos), bytes <= (filler.size() == 1 ? 17u : 8u));
                     }
                 }
             }

tests/src/unit-testsuites.cpp

@@ -218,7 +218,11 @@ TEST_CASE("compliance tests from nativejson-benchmark")
             n1e308[0] = '[';
             n1e308[1] = '1';
             n1e308[310] = ']';
+#if JSON_STRICT_NUL_HANDLING
+            n1e308.pop_back(); // a NUL byte after the value is a syntax error in strict mode
+#else
             n1e308[311] = '\0';
+#endif
             TEST_DOUBLE(n1e308, 1E308);
         }
 

tests/src/unit-throw_messages.cpp

@@ -54,8 +54,8 @@ TEST_CASE("exception messages of out-of-line throw sites")
 
     SECTION("at")
     {
-        const json carr = arr;
-        const json cobj = obj;
+        const json& carr = arr;
+        const json& cobj = obj;
         CHECK_MSG((void)arr.at(static_cast<json::size_type>(10)), "[json.exception.out_of_range.401] array index 10 is out of range");
         CHECK_MSG((void)carr.at(static_cast<json::size_type>(3)), "[json.exception.out_of_range.401] array index 3 is out of range");
         CHECK_MSG((void)num.at(static_cast<json::size_type>(0)), "[json.exception.type_error.304] cannot use at() with number");
@@ -65,7 +65,7 @@ TEST_CASE("exception messages of out-of-line throw sites")
         CHECK_MSG((void)num.at("a"), "[json.exception.type_error.304] cannot use at() with number");
 
         nlohmann::ordered_json oobj = {{"a", 1}};
-        const nlohmann::ordered_json coobj = oobj;
+        const nlohmann::ordered_json& coobj = oobj;
         CHECK_MSG((void)oobj.at("z"), "[json.exception.out_of_range.403] key 'z' not found");
         CHECK_MSG((void)coobj.at("z"), "[json.exception.out_of_range.403] key 'z' not found");
         CHECK_MSG((void)coobj.at(std::string("zz")), "[json.exception.out_of_range.403] key 'zz' not found");
@@ -94,9 +94,10 @@ TEST_CASE("exception messages of out-of-line throw sites")
         CHECK_MSG(obj.update(arr.begin(), arr2.end()), "[json.exception.invalid_iterator.210] iterators do not fit");
     }
 
+#if !defined(JSON_NOEXCEPTION) // patch_msg() catches the exceptions, which JSON_NOEXCEPTION turns into std::abort()
     SECTION("patch")
     {
-        const auto patch_msg = [](const char* doc, const char* patch)
+        const auto patch_msg = [](const char* doc, const char* patch) -> std::string
         {
             try
             {
@@ -105,16 +106,23 @@ TEST_CASE("exception messages of out-of-line throw sites")
             }
             catch (const json::exception& e)
             {
-                // with JSON_DIAGNOSTICS, what() names the offending value like "(/0) "; drop it
+                // with JSON_DIAGNOSTICS, what() names the offending value like "(/0) ",
+                // and with JSON_DIAGNOSTIC_POSITIONS its position like "(bytes 0-2) "; drop both
                 std::string msg = e.what();
-                const auto pos = msg.find(" (/");
-                if (pos != std::string::npos)
+                for (const char* marker :
+            {
+                " (/", " (bytes "
+            })
                 {
-                    msg.erase(pos + 1, msg.find(") ", pos) - pos + 1);
+                    const auto pos = msg.find(marker);
+                    if (pos != std::string::npos)
+                    {
+                        msg.erase(pos + 1, msg.find(") ", pos) - pos + 1);
+                    }
                 }
                 return msg;
             }
-            return std::string();
+            return {};
         };
 
         CHECK(patch_msg("{}", "{}") == "[json.exception.parse_error.104] parse error: JSON patch must be an array of objects");
@@ -132,4 +140,5 @@ TEST_CASE("exception messages of out-of-line throw sites")
         CHECK(patch_msg("{\"a\":1}", "[{\"op\":\"test\",\"path\":\"/a\",\"value\":2}]") == "[json.exception.other_error.501] unsuccessful: {\"op\":\"test\",\"path\":\"/a\",\"value\":2}");
         CHECK(patch_msg("{\"a\":1}", "[{\"op\":\"move\",\"path\":\"/a\"}]") == "[json.exception.parse_error.105] parse error: operation 'move' must have member 'from'");
     }
+#endif
 }