Regenerate the amalgamation

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

.github/workflows/windows.yml

@@ -166,21 +166,19 @@ 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.
-      # 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.
+      # 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.
       - 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="-fuse-ld=lld -lwinpthread" ^
+             -DCMAKE_EXE_LINKER_FLAGS="-lwinpthread" ^
              -G"MinGW Makefiles" ^
              -DCMAKE_BUILD_TYPE=Debug ^
              -DJSON_BuildTests=On

include/nlohmann/detail/conversions/to_json.hpp

@@ -13,7 +13,7 @@
     #include <optional> // optional
 #endif
 
-#include <iterator> // begin, end, make_move_iterator, move_iterator
+#include <iterator> // begin, end
 #include <memory> // allocator_traits
 #include <string> //  basic_string, char_traits
 #include <tuple> // tuple, get
@@ -48,32 +48,6 @@ 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<>
@@ -200,7 +174,7 @@ 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>(make_move_iterator_if_mutable(begin(arr)), make_move_iterator_if_mutable(end(arr))));
+        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))));
         j.replace_value(value_t::array, value);
     }
 
@@ -261,7 +235,7 @@ 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>(make_move_iterator_if_mutable(begin(obj)), make_move_iterator_if_mutable(end(obj))));
+        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))));
         j.replace_value(value_t::object, value);
     }
 
@@ -439,27 +413,25 @@ 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; 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)
+// rvalue array-like containers
 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) // NOLINT(cppcoreguidelines-missing-std-forward)
+inline void to_json(BasicJsonType& j, CompatibleArrayType && arr)
 {
     external_constructor<value_t::array>::construct_moving(j, arr);
 }
@@ -537,8 +509,7 @@ inline void to_json(BasicJsonType& j, const EnumKeyedMap& map)
 }
 #endif
 
-// rvalue object-like containers (views have no key_type and mapped_type, so
-// they are no compatible object type)
+// rvalue object-like containers
 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>>,
@@ -546,7 +517,7 @@ 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) // NOLINT(cppcoreguidelines-missing-std-forward)
+inline void to_json(BasicJsonType& j, CompatibleObjectType && obj)
 {
     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 auto fractional_low_shift = static_cast<unsigned>(extra_shift);
+    constexpr unsigned 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

@@ -494,7 +494,8 @@ 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
-    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));
+    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));
 }
 
 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_UNLIKELY(!m_object->is_object()))
+        if (JSON_HEDLEY_LIKELY(m_object->is_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;
         }
 
-        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);
     }
 
     /*!

include/nlohmann/detail/json_pointer.hpp

@@ -11,7 +11,6 @@
 #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
@@ -335,7 +334,7 @@ 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;
@@ -530,10 +529,10 @@ class json_pointer
 
         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::numeric_limits<std::size_t>::max)());
+            std::size_t h = parent * static_cast<std::size_t>(0x9E3779B97F4A7C15ULL);
             for (std::size_t i = 0; i < token.size(); ++i)
             {
-                h = (h ^ static_cast<unsigned char>(token[i])) * static_cast<std::size_t>(0x100000001B3ULL & (std::numeric_limits<std::size_t>::max)());
+                h = (h ^ static_cast<unsigned char>(token[i])) * static_cast<std::size_t>(0x100000001B3ULL);
             }
             return h ^ (h >> 29u);
         }

include/nlohmann/detail/output/binary_writer.hpp

@@ -23,6 +23,7 @@
     #include <cstdlib> // _byteswap_ushort, _byteswap_ulong, _byteswap_uint64
 #endif
 
+#include <nlohmann/detail/bit_ops.hpp>
 #include <nlohmann/detail/input/binary_reader.hpp>
 #include <nlohmann/detail/input/string_scan.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
@@ -204,24 +205,12 @@ class binary_writer
             }
 
             case value_t::number_integer:
-            {
-                if (j.m_data.m_value.number_integer >= 0)
-                {
-                    // CBOR does not differentiate between positive signed
-                    // integers and unsigned integers
-                    write_cbor_head(0x00, static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
-                }
-                else
-                {
-                    // a negative integer n is encoded as -1 - n
-                    write_cbor_head(0x20, static_cast<std::uint64_t>(-1 - j.m_data.m_value.number_integer));
-                }
-                break;
-            }
-
             case value_t::number_unsigned:
             {
-                write_cbor_head(0x00, conditional_static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
+                // one case for both, so that an array mixing negative
+                // (number_integer) and non-negative (number_unsigned) values
+                // does not mispredict the switch
+                write_cbor_integer(j);
                 break;
             }
 
@@ -256,13 +245,7 @@ class binary_writer
 
             case value_t::array:
             {
-                // step 1: write control byte and the array size
-                write_cbor_head(0x80, j.m_data.m_value.array->size());
-
-                for (const auto& el : *j.m_data.m_value.array)
-                {
-                    write_cbor(el, depth + 1);
-                }
+                write_cbor_array(j, depth);
                 break;
             }
 
@@ -420,54 +403,12 @@ class binary_writer
             }
 
             case value_t::number_integer:
-            {
-                if (j.m_data.m_value.number_integer >= 0)
-                {
-                    // MessagePack does not differentiate between positive
-                    // signed integers and unsigned integers.
-                    write_msgpack_unsigned(static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
-                }
-                else
-                {
-                    if (j.m_data.m_value.number_integer >= -32)
-                    {
-                        // negative fixnum
-                        write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
-                    }
-                    else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int8_t>::min)() &&
-                             j.m_data.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
-                    {
-                        // int 8
-                        oa.write_character(to_char_type(0xD0));
-                        write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
-                    }
-                    else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int16_t>::min)() &&
-                             j.m_data.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
-                    {
-                        // int 16
-                        oa.write_character(to_char_type(0xD1));
-                        write_number(static_cast<std::int16_t>(j.m_data.m_value.number_integer));
-                    }
-                    else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int32_t>::min)() &&
-                             j.m_data.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
-                    {
-                        // int 32
-                        oa.write_character(to_char_type(0xD2));
-                        write_number(static_cast<std::int32_t>(j.m_data.m_value.number_integer));
-                    }
-                    else
-                    {
-                        // int 64
-                        oa.write_character(to_char_type(0xD3));
-                        write_number(static_cast<std::int64_t>(j.m_data.m_value.number_integer));
-                    }
-                }
-                break;
-            }
-
             case value_t::number_unsigned:
             {
-                write_msgpack_unsigned(static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
+                // one case for both, so that an array mixing negative
+                // (number_integer) and non-negative (number_unsigned) values
+                // does not mispredict the switch
+                write_msgpack_integer(j, std::integral_constant<bool, msgpack_integers_fit_64_bits()>());
                 break;
             }
 
@@ -485,13 +426,7 @@ class binary_writer
 
             case value_t::array:
             {
-                // step 1: write control byte and the array size
-                write_msgpack_array_prefix(j.m_data.m_value.array->size(), j);
-
-                for (const auto& el : *j.m_data.m_value.array)
-                {
-                    write_msgpack(el, depth + 1);
-                }
+                write_msgpack_array(j, depth);
                 break;
             }
 
@@ -1951,6 +1886,316 @@ class binary_writer
         }
     }
 
+    /*!
+    @brief size class of an unsigned integer from its bit length
+
+    1, 2, 3, or 4 if @a x fits 1, 2, 4, or 8 bytes. Looked up from the number
+    of leading zero bits instead of found by branches: the sizes of a stream
+    of numbers are hard to predict, and a mispredicted branch costs more than
+    writing the number. (A table, as comparisons are vectorized by clang into
+    slower code.)
+    */
+    static unsigned integer_size_class(const std::uint64_t x) noexcept
+    {
+        static constexpr std::array<std::uint8_t, 64> size_class_by_leading_zeros =
+        {
+            {
+                4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+                3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+                2, 2, 2, 2, 2, 2, 2, 2,
+                1, 1, 1, 1, 1, 1, 1, 1
+            }
+        };
+        // x | 1 keeps count_leading_zeros() away from 0
+        return size_class_by_leading_zeros[static_cast<std::size_t>(count_leading_zeros(x | 1u))];
+    }
+
+    /*!
+    @brief encode @a first_byte and the low-order bytes of @a value that
+           @a size_class calls for (none, or 1, 2, 4, or 8) in network order
+           to @a out
+    @return the number of characters of the encoding; up to
+            @ref integer_encoding_space characters at @a out are overwritten
+
+    The bytes are written as one byte and one 8-byte word whose bytes after
+    the value are scratch that the caller drops, so that writing them does not
+    depend on the size class. For class 0 the word is all scratch; it is
+    shifted by 60 bits rather than 64, which would be undefined.
+    */
+    std::size_t encode_first_byte_and_tail(CharType* out, const std::uint8_t first_byte, const unsigned size_class, const std::uint64_t value) const noexcept
+    {
+        out[0] = to_char_type(first_byte);
+        const unsigned unused_bits = 64u - ((8u << size_class) >> 1u);
+        const std::uint64_t tail = is_little_endian ? byte_swap(value) >> unused_bits : value << unused_bits;
+        std::memcpy(out + 1, &tail, sizeof(tail));
+        return ((std::size_t{1} << size_class) >> 1u) + 1;
+    }
+
+    /// characters encode_first_byte_and_tail() may overwrite: the first byte
+    /// and one 8-byte word
+    static constexpr std::size_t integer_encoding_space = 9;
+
+    /*!
+    @brief the 64 bits of a number_integer or number_unsigned value, and a mask
+           that is all ones if it is negative, else zero
+
+    Selected through masks rather than branches, as the type and the sign of
+    the values in an array of mixed signs alternate unpredictably (non-negative
+    integers are number_unsigned after parsing). Up to 64 bits, the sign is bit
+    63 of the result (a narrower integer is sign-extended); computing it with
+    masks keeps GCC from branching on the type. A wider integer has to be
+    compared.
+    */
+    static std::uint64_t integer_bits(const BasicJsonType& j, std::uint64_t& sign_mask) noexcept
+    {
+        const bool is_signed = j.m_data.m_type == value_t::number_integer;
+        const std::uint64_t raw = is_signed
+                                  ? static_cast<std::uint64_t>(j.m_data.m_value.number_integer)
+                                  : static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned);
+        sign_mask = sizeof(typename BasicJsonType::number_integer_t) <= sizeof(std::uint64_t)
+                    ? (std::uint64_t{0} - static_cast<std::uint64_t>(is_signed)) & (std::uint64_t{0} - (raw >> 63u))
+                    : std::uint64_t{0} - static_cast<std::uint64_t>(is_signed && j.m_data.m_value.number_integer < 0);
+        return raw;
+    }
+
+    /*!
+    @brief encode the head of a CBOR integer to @a out without branching on its
+           size
+    @return the number of characters of the head
+
+    Same output as @ref write_cbor_head. The lengths of strings and containers
+    are mostly predictable, so their heads keep the branches; the sizes of a
+    run of integers are not, so an integer's head is assembled without them.
+    */
+    std::size_t encode_cbor_integer_head(CharType* out, const std::uint8_t major_type, const std::uint64_t argument) const noexcept
+    {
+        // an argument of at most 23 is in size class 1 (one byte) and is moved
+        // to class 0, the first byte, by subtracting 1
+        const auto is_immediate = static_cast<unsigned>(argument <= 0x17u);
+        const unsigned size_class = integer_size_class(argument) - is_immediate;
+
+        // the first byte: the argument itself if it is immediate, else
+        // 0x17 + size_class, selected through a mask
+        const std::uint64_t immediate_mask = std::uint64_t{0} - is_immediate;
+        const auto first_byte = static_cast<std::uint8_t>(major_type + ((argument & immediate_mask) | ((0x17u + size_class) & ~immediate_mask)));
+        return encode_first_byte_and_tail(out, first_byte, size_class, argument);
+    }
+
+    /*!
+    @brief write an array value (head and elements) as CBOR
+
+    Integer elements, the most common scalar, are written without a call to
+    @ref write_cbor. The loop is kept out of line: inlined into write_cbor, its
+    registers would be saved and restored on every call of write_cbor, which
+    is one call per value nested in an object.
+    */
+    JSON_HEDLEY_NEVER_INLINE
+    void write_cbor_array(const BasicJsonType& j, const std::size_t depth)
+    {
+        write_cbor_head(0x80, j.m_data.m_value.array->size());
+        write_array_elements(j, [this](CharType * out, const BasicJsonType & el)
+        {
+            return encode_cbor_integer(out, el);
+        }, [this, depth](const BasicJsonType & el)
+        {
+            write_cbor(el, depth + 1);
+        });
+    }
+
+    /*!
+    @brief write the elements of the array @a j, runs of integers with
+           @a encode_integer and all other values with @a write_value
+
+    Runs of integers are encoded straight into space reserved from the sink
+    for a whole run: the write pointer stays a local, where it would otherwise
+    be reloaded from the sink for every value, as a store of a character may
+    alias it.
+    */
+    template<typename EncodeInteger, typename WriteValue>
+    void write_array_elements(const BasicJsonType& j, EncodeInteger encode_integer, WriteValue write_value)
+    {
+        constexpr std::size_t max_run = max_reserve_size / integer_encoding_space;
+        auto it = j.m_data.m_value.array->begin();
+        const auto end = j.m_data.m_value.array->end();
+        while (it != end)
+        {
+            if (it->is_number_integer())
+            {
+                CharType* const start = oa.reserve(max_run * integer_encoding_space);
+                CharType* out = start;
+                for (std::size_t n = 0; n < max_run && it != end && it->is_number_integer(); ++n, ++it)
+                {
+                    out += encode_integer(out, *it);
+                }
+                oa.commit(static_cast<std::size_t>(out - start));
+            }
+            else
+            {
+                write_value(*it);
+                ++it;
+            }
+        }
+    }
+
+    /*!
+    @brief write a number_integer or number_unsigned value as a CBOR integer
+
+    A negative integer n has major type 1 and the argument -1 - n, which is ~n.
+    Kept out of line, like the other per-value paths, so that write_cbor stays
+    small (runs of integers in an array are encoded inline instead).
+    */
+    JSON_HEDLEY_NEVER_INLINE
+    void write_cbor_integer(const BasicJsonType& j)
+    {
+        oa.commit(encode_cbor_integer(oa.reserve(integer_encoding_space), j));
+    }
+
+    /// encode a number_integer or number_unsigned value to @a out (see
+    /// @ref write_cbor_integer) and return the number of characters
+    std::size_t encode_cbor_integer(CharType* out, const BasicJsonType& j) const noexcept
+    {
+        std::uint64_t sign_mask = 0;
+        const std::uint64_t raw = integer_bits(j, sign_mask);
+        // ~raw is -1 - n in the 64 bits that are written
+        return encode_cbor_integer_head(out, static_cast<std::uint8_t>(sign_mask & 0x20u), raw ^ sign_mask);
+    }
+
+    /*!
+    @brief whether the MessagePack integers of BasicJsonType are written by
+           @ref encode_msgpack_integer
+
+    It picks the format from the low 64 bits; a wider number type keeps the
+    range checks of @ref write_msgpack on the whole value.
+    */
+    static constexpr bool msgpack_integers_fit_64_bits() noexcept
+    {
+        return sizeof(typename BasicJsonType::number_integer_t) <= sizeof(std::uint64_t)
+               && sizeof(typename BasicJsonType::number_unsigned_t) <= sizeof(std::uint64_t);
+    }
+
+    /*!
+    @brief write a number_integer or number_unsigned value as a MessagePack
+           integer without branching on its sign or size
+
+    Same output as @ref write_msgpack: a non-negative integer as positive fixint
+    (< 128) or uint 8/16/32/64, a negative one as negative fixint (>= -32) or
+    int 8/16/32/64. Kept out of line (see @ref write_cbor_integer).
+    */
+    JSON_HEDLEY_NEVER_INLINE
+    void write_msgpack_integer(const BasicJsonType& j, std::true_type /*fits_64_bits*/)
+    {
+        oa.commit(encode_msgpack_integer(oa.reserve(integer_encoding_space), j));
+    }
+
+    /// encode a number_integer or number_unsigned value to @a out (see
+    /// @ref write_msgpack_integer) and return the number of characters
+    std::size_t encode_msgpack_integer(CharType* out, const BasicJsonType& j) const noexcept
+    {
+        std::uint64_t sign_mask = 0;
+        const std::uint64_t raw = integer_bits(j, sign_mask);
+
+        // A negative n fits int 8/16/32 exactly if 2 * (-1 - n) + 1 fits
+        // uint 8/16/32, so x gives the size class of either sign.
+        const std::uint64_t is_negative = sign_mask & 1u;
+        const std::uint64_t x = ((raw ^ sign_mask) << is_negative) | is_negative;
+
+        // A fixint is at most 127, or at least -32 (x at most 63). It is in
+        // size class 1 and is moved to class 0, the first byte, by subtracting 1.
+        const auto is_fixint = static_cast<unsigned>(x <= (127u ^ (sign_mask & 64u)));
+        const unsigned size_class = integer_size_class(x) - is_fixint;
+
+        // the first byte: the low byte of the integer for a fixint, else the
+        // marker 0xCC..0xCF (uint) or 0xD0..0xD3 (int), selected through a mask
+        const std::uint64_t fixint_mask = std::uint64_t{0} - is_fixint;
+        const std::uint64_t marker = 0xCBu + size_class + (sign_mask & 4u);
+        const auto first_byte = static_cast<std::uint8_t>((raw & fixint_mask) | (marker & ~fixint_mask));
+        return encode_first_byte_and_tail(out, first_byte, size_class, raw);
+    }
+
+    /// write a number_integer or number_unsigned value of a number type wider
+    /// than 64 bits as a MessagePack integer, with range checks on the whole value
+    void write_msgpack_integer(const BasicJsonType& j, std::false_type /*fits_64_bits*/)
+    {
+        if (j.m_data.m_type == value_t::number_unsigned)
+        {
+            write_msgpack_unsigned(static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
+            return;
+        }
+
+        if (j.m_data.m_value.number_integer >= 0)
+        {
+            // MessagePack does not differentiate between positive
+            // signed integers and unsigned integers.
+            write_msgpack_unsigned(static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
+        }
+        else
+        {
+            if (j.m_data.m_value.number_integer >= -32)
+            {
+                // negative fixnum
+                write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
+            }
+            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int8_t>::min)() &&
+                     j.m_data.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
+            {
+                // int 8
+                oa.write_character(to_char_type(0xD0));
+                write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
+            }
+            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int16_t>::min)() &&
+                     j.m_data.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
+            {
+                // int 16
+                oa.write_character(to_char_type(0xD1));
+                write_number(static_cast<std::int16_t>(j.m_data.m_value.number_integer));
+            }
+            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int32_t>::min)() &&
+                     j.m_data.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
+            {
+                // int 32
+                oa.write_character(to_char_type(0xD2));
+                write_number(static_cast<std::int32_t>(j.m_data.m_value.number_integer));
+            }
+            else
+            {
+                // int 64
+                oa.write_character(to_char_type(0xD3));
+                write_number(static_cast<std::int64_t>(j.m_data.m_value.number_integer));
+            }
+        }
+    }
+
+    /*!
+    @brief write an array value (head and elements) as MessagePack
+
+    See @ref write_cbor_array.
+    */
+    JSON_HEDLEY_NEVER_INLINE
+    void write_msgpack_array(const BasicJsonType& j, const std::size_t depth)
+    {
+        write_msgpack_array_prefix(j.m_data.m_value.array->size(), j);
+        write_msgpack_array_elements(j, depth, std::integral_constant<bool, msgpack_integers_fit_64_bits()>());
+    }
+
+    void write_msgpack_array_elements(const BasicJsonType& j, const std::size_t depth, std::true_type /*fits_64_bits*/)
+    {
+        write_array_elements(j, [this](CharType * out, const BasicJsonType & el)
+        {
+            return encode_msgpack_integer(out, el);
+        }, [this, depth](const BasicJsonType & el)
+        {
+            write_msgpack(el, depth + 1);
+        });
+    }
+
+    void write_msgpack_array_elements(const BasicJsonType& j, const std::size_t depth, std::false_type /*fits_64_bits*/)
+    {
+        for (const auto& el : *j.m_data.m_value.array)
+        {
+            write_msgpack(el, depth + 1);
+        }
+    }
+
     /*!
     @brief write an object key as a CBOR text string
 

include/nlohmann/detail/output/output_adapters.hpp

@@ -8,7 +8,10 @@
 
 #pragma once
 
+#include <algorithm> // max
+#include <array> // array
 #include <cstddef> // size_t
+#include <cstring> // memcpy
 #include <memory> // shared_ptr, make_shared
 #include <string> // basic_string
 #include <type_traits> // conditional, integral_constant, is_same
@@ -48,32 +51,170 @@ template<typename CharType> struct output_adapter_protocol
 template<typename CharType>
 using output_adapter_t = std::shared_ptr<output_adapter_protocol<CharType>>;
 
+/// the largest number of characters a writer may reserve() from a sink at once;
+/// output_vector_sink also appends writes of at least this size with insert()
+constexpr std::size_t max_reserve_size = 256;
+
 /// @brief non-virtual output sink writing into a std::vector
 ///
 /// This sink is not part of the virtual output_adapter_protocol hierarchy: it is
 /// passed to binary_writer by value as a template parameter, so
 /// write_character()/write_characters() are ordinary (inlinable) calls with no
 /// vtable lookup and no shared_ptr. It is used for the common
-/// `to_cbor`/`to_msgpack`/... into a std::vector. output_vector_adapter below
-/// wraps this same sink to provide the virtual interface.
+/// `to_cbor`/`to_msgpack`/... into a std::vector.
+///
+/// Most writes are a few bytes - a type marker, or a number of 1, 2, 4, or 8
+/// bytes - and appending those with push_back() or insert() cost more than
+/// encoding them: insert() is an out-of-line call into a routine that can insert
+/// anywhere, and resize() is one as well with libstdc++. The sink therefore keeps
+/// its own write position: it grows the vector geometrically ahead of the
+/// position and copies each write to it, so a write is a capacity check and a
+/// short copy. The destructor shrinks the vector to the bytes actually written,
+/// also when a write throws; shrinking a vector never allocates. The sink owns
+/// that trim, so it can be moved but not copied, and the vector must not be used
+/// while the sink is alive.
 template<typename CharType, typename AllocatorType = std::allocator<CharType>>
 class output_vector_sink
 {
   public:
     explicit output_vector_sink(std::vector<CharType, AllocatorType>& vec) noexcept
+        : v(&vec), position(vec.size())
+    {}
+
+    output_vector_sink(const output_vector_sink&) = delete;
+    output_vector_sink& operator=(const output_vector_sink&) = delete;
+    output_vector_sink& operator=(output_vector_sink&&) = delete;
+
+    output_vector_sink(output_vector_sink&& other) noexcept
+        : v(other.v), position(other.position)
+    {
+        other.v = nullptr;
+    }
+
+    ~output_vector_sink()
+    {
+        if (v != nullptr)
+        {
+            v->resize(position);
+        }
+    }
+
+    // always inlined: GCC otherwise keeps these out of line in a large
+    // translation unit, and a call per byte or number costs more than the write
+    JSON_HEDLEY_ALWAYS_INLINE
+    void write_character(CharType c)
+    {
+        if (JSON_HEDLEY_UNLIKELY(position == v->size()))
+        {
+            grow(1);
+        }
+        (*v)[position++] = c;
+    }
+
+    // no JSON_HEDLEY_NON_NULL here: binary_writer legitimately passes a null
+    // pointer with length 0 for empty strings/binary values; memcpy must not
+    // see it.
+    JSON_HEDLEY_ALWAYS_INLINE
+    void write_characters(const CharType* s, std::size_t length)
+    {
+        if (JSON_HEDLEY_UNLIKELY(v->size() - position < length))
+        {
+            if (length >= max_reserve_size)
+            {
+                append(s, length);
+                return;
+            }
+            grow(length);
+        }
+        if (length != 0)
+        {
+            std::memcpy(v->data() + position, s, length * sizeof(CharType));
+            position += length;
+        }
+    }
+
+    /// @brief space for writing up to @a length characters directly
+    ///
+    /// Returns a pointer to at least @a length (at most @ref max_reserve_size)
+    /// writable characters at the write position; @ref commit then keeps the
+    /// first ones of them. A writer can store whole words there and keep only
+    /// the bytes it needs, and keep its write pointer in a register across many
+    /// values instead of updating the sink after each.
+    JSON_HEDLEY_ALWAYS_INLINE
+    CharType* reserve(const std::size_t length)
+    {
+        JSON_ASSERT(length <= max_reserve_size);
+        if (JSON_HEDLEY_UNLIKELY(v->size() - position < length))
+        {
+            grow(length);
+        }
+        return v->data() + position;
+    }
+
+    /// keep the first @a length characters written to the space from reserve()
+    JSON_HEDLEY_ALWAYS_INLINE
+    void commit(const std::size_t length) noexcept
+    {
+        position += length;
+    }
+
+  private:
+    /// make room for at least @a length more characters after the position;
+    /// kept out of line so that the write functions stay small enough for
+    /// GCC to inline them into the writer
+    JSON_HEDLEY_NEVER_INLINE
+    void grow(const std::size_t length)
+    {
+        // use the capacity the vector already has, else at least double it;
+        // never less than 64 characters, so that a small value does not
+        // reallocate for every few bytes
+        const std::size_t needed = position + length;
+        v->resize((std::max)(std::size_t{64}, needed <= v->capacity()
+                             ? v->capacity()
+                             : (std::max)(needed, v->capacity() * 2)));
+    }
+
+    /// append @a length (at least max_reserve_size) characters that do not fit
+    /// the space ahead of the position: insert() copies them once into the
+    /// grown vector, where grow() would first zero the new space and then copy
+    /// over it - noticeable for a large string or binary value
+    JSON_HEDLEY_NEVER_INLINE
+    void append(const CharType* s, const std::size_t length)
+    {
+        v->resize(position);
+        if (v->capacity() - position < length)
+        {
+            // grow geometrically, with room for the writes that follow, so
+            // that the next grow() need not reallocate right away
+            v->reserve((std::max)(v->capacity() * 2, position + length + max_reserve_size));
+        }
+        v->insert(v->end(), s, s + length);
+        position = v->size();
+    }
+
+    std::vector<CharType, AllocatorType>* v;
+    /// number of characters of *v written so far
+    std::size_t position;
+};
+
+/// output adapter for byte vectors
+template<typename CharType, typename AllocatorType = std::allocator<CharType>>
+class output_vector_adapter : public output_adapter_protocol<CharType>
+{
+  public:
+    explicit output_vector_adapter(std::vector<CharType, AllocatorType>& vec) noexcept
         : v(vec)
     {}
 
-    void write_character(CharType c)
+    void write_character(CharType c) override
     {
         v.push_back(c);
     }
 
     // no JSON_HEDLEY_NON_NULL here: binary_writer legitimately passes a null
-    // pointer with length 0 for empty strings/binary values. Appending an empty
-    // range is a no-op; the type-erased path tolerates this via the (unattributed)
-    // virtual base, and the concrete sink must do the same.
-    void write_characters(const CharType* s, std::size_t length)
+    // pointer with length 0 for empty strings/binary values; appending an empty
+    // range is a no-op
+    void write_characters(const CharType* s, std::size_t length) override
     {
         v.insert(v.end(), s, s + length);
     }
@@ -82,33 +223,6 @@ class output_vector_sink
     std::vector<CharType, AllocatorType>& v;
 };
 
-/// output adapter for byte vectors
-///
-/// The appending itself lives in output_vector_sink; this class only adds the
-/// virtual output_adapter_protocol interface on top of it, so both the
-/// type-erased and the templated path share one implementation.
-template<typename CharType, typename AllocatorType = std::allocator<CharType>>
-class output_vector_adapter : public output_adapter_protocol<CharType>
-{
-  public:
-    explicit output_vector_adapter(std::vector<CharType, AllocatorType>& vec) noexcept
-        : sink(vec)
-    {}
-
-    void write_character(CharType c) override
-    {
-        sink.write_character(c);
-    }
-
-    void write_characters(const CharType* s, std::size_t length) override
-    {
-        sink.write_characters(s, length);
-    }
-
-  private:
-    output_vector_sink<CharType, AllocatorType> sink;
-};
-
 #ifndef JSON_NO_IO
 /// output adapter for output streams
 template<typename CharType>
@@ -188,8 +302,24 @@ class output_adapter_sink
         oa->write_characters(s, length);
     }
 
+    /// space for writing up to @a length characters (see
+    /// output_vector_sink::reserve)
+    CharType* reserve(const std::size_t length) noexcept
+    {
+        JSON_ASSERT(length <= max_reserve_size);
+        static_cast<void>(length);
+        return reserved.data();
+    }
+
+    /// write the first @a length characters written to the space from reserve()
+    void commit(const std::size_t length)
+    {
+        oa->write_characters(reserved.data(), length);
+    }
+
   private:
     output_adapter_t<CharType> oa;
+    std::array<CharType, max_reserve_size> reserved{};
 };
 
 /// @brief whether std::basic_string<CharType> has a non-deprecated std::char_traits

include/nlohmann/json.hpp

@@ -29,7 +29,6 @@
 #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
@@ -755,20 +754,26 @@ 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;
-                return std::all_of(a.begin(), a.end(), [](const basic_json & el)
+                for (auto it = a.rbegin(); it != a.rend(); ++it)
                 {
-                    return has_no_children(el);
-                });
+                    if (!has_no_children(*it))
+                    {
+                        return false;
+                    }
+                }
+                return true;
             }
-            const auto& o = *v.m_data.m_value.object;
-            return std::all_of(o.begin(), o.end(), [](const typename object_t::value_type & el)
+            for (const auto& el : *v.m_data.m_value.object)
             {
-                return has_no_children(el.second);
-            });
+                if (!has_no_children(el.second))
+                {
+                    return false;
+                }
+            }
+            return true;
         }
 
         // The walk in destroy_container() may take the children of a
@@ -1225,7 +1230,7 @@ public:
     }
 
     template < typename O = object_t, detail::enable_if_t < detail::has_stable_elements<O>::value, int > = 0 >
-    std::size_t object_capacity() const noexcept
+    static constexpr std::size_t object_capacity() noexcept
     {
         return 0;
     }
@@ -1237,7 +1242,7 @@ 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 >
-    std::size_t object_capacity() const noexcept
+    static constexpr std::size_t object_capacity() noexcept
     {
         return detail::unknown_size();
     }
@@ -3038,21 +3043,18 @@ 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")));
     }
 
@@ -3060,8 +3062,6 @@ 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));
     }
 
@@ -3070,8 +3070,6 @@ 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));
     }
 
@@ -4895,19 +4893,19 @@ public:
     iterator insert(const_iterator pos, const basic_json& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
+        if (JSON_HEDLEY_LIKELY(is_array()))
         {
-            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);
         }
 
-        // 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);
     }
 
     /// @brief inserts element into array
@@ -4915,21 +4913,21 @@ public:
     iterator insert(const_iterator pos, basic_json&& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
+        if (JSON_HEDLEY_LIKELY(is_array()))
         {
-            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));
         }
 
-        // 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);
     }
 
     /// @brief inserts copies of element into array
@@ -4937,19 +4935,19 @@ 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_UNLIKELY(!is_array()))
+        if (JSON_HEDLEY_LIKELY(is_array()))
         {
-            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);
         }
 
-        // 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);
     }
 
     /// @brief inserts range of elements into array
@@ -5455,7 +5453,7 @@ 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) /* NOLINT(readability/braces) */                         \
+    if (lhs.m_data.m_type == rhs.m_data.m_type)                                                          \
     {                                                                                                    \
         switch (lhs.m_data.m_type)                                                                       \
         {                                                                                                \

include/nlohmann/ordered_map.hpp

@@ -23,7 +23,6 @@
 #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
 

tests/src/unit-binary_writer_sinks.cpp

@@ -11,8 +11,10 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
+#include <array>
 #include <cstdint>
 #include <limits>
+#include <sstream>
 #include <string>
 #include <vector>
 
@@ -35,6 +37,17 @@ std::vector<json> test_values()
         big_object[std::to_string(i)] = i;
     }
 
+    // large strings and binary values between small ones: a write too large
+    // for the space the vector sink has ahead takes a different path than a
+    // small one, and the small writes after it must still land behind it
+    json large_payloads = json::array();
+    for (int i = 0; i < 50; ++i)
+    {
+        large_payloads.push_back(std::string(300, static_cast<char>('a' + (i % 26))));
+        large_payloads.push_back(i);
+        large_payloads.push_back(json::binary(std::vector<std::uint8_t>(static_cast<std::size_t>(100 * i), static_cast<std::uint8_t>(i))));
+    }
+
     return
     {
         json(nullptr), json(true), json(false),
@@ -46,7 +59,8 @@ std::vector<json> test_values()
         json::array(), json::object(),
         json::array({1, 2, 3}), json({{"a", 1}, {"b", nullptr}}),
         json({{"nested", {{"deep", json::array({1, "two", 3.0, nullptr})}}}}),
-        big_array, big_object
+        big_array, big_object, large_payloads,
+        json::binary(std::vector<std::uint8_t>(5000, 0x42))
     };
 }
 
@@ -170,6 +184,258 @@ TEST_CASE("binary writer output sinks")
     }
 }
 
+namespace
+{
+
+// the CBOR head of an integer, encoded independently of binary_writer
+void reference_cbor_head(std::vector<std::uint8_t>& out, const std::uint8_t major_type, const std::uint64_t argument)
+{
+    if (argument <= 23)
+    {
+        out.push_back(static_cast<std::uint8_t>(major_type + argument));
+        return;
+    }
+
+    int length = 8;
+    std::uint8_t additional = 27;
+    if (argument <= 0xFF)
+    {
+        length = 1;
+        additional = 24;
+    }
+    else if (argument <= 0xFFFF)
+    {
+        length = 2;
+        additional = 25;
+    }
+    else if (argument <= 0xFFFFFFFF)
+    {
+        length = 4;
+        additional = 26;
+    }
+
+    out.push_back(static_cast<std::uint8_t>(major_type + additional));
+    for (int i = length - 1; i >= 0; --i)
+    {
+        out.push_back(static_cast<std::uint8_t>(argument >> (8 * i)));
+    }
+}
+
+// the CBOR encoding of an integer value
+void reference_cbor_integer(std::vector<std::uint8_t>& out, const json& j)
+{
+    if (j.is_number_unsigned())
+    {
+        reference_cbor_head(out, 0x00, j.get<std::uint64_t>());
+        return;
+    }
+
+    const auto n = j.get<std::int64_t>();
+    if (n >= 0)
+    {
+        reference_cbor_head(out, 0x00, static_cast<std::uint64_t>(n));
+    }
+    else
+    {
+        reference_cbor_head(out, 0x20, static_cast<std::uint64_t>(-1 - n));
+    }
+}
+
+// the MessagePack encoding of an integer value, encoded independently of
+// binary_writer
+void reference_msgpack_integer(std::vector<std::uint8_t>& out, const json& j)
+{
+    const auto put = [&out](const std::uint8_t marker, const std::uint64_t bits, const int length)
+    {
+        out.push_back(marker);
+        for (int i = length - 1; i >= 0; --i)
+        {
+            out.push_back(static_cast<std::uint8_t>(bits >> (8 * i)));
+        }
+    };
+
+    if (j.is_number_unsigned() || j.get<std::int64_t>() >= 0)
+    {
+        const auto u = j.get<std::uint64_t>();
+        if (u < 128)
+        {
+            out.push_back(static_cast<std::uint8_t>(u));
+        }
+        else if (u <= 0xFF)
+        {
+            put(0xCC, u, 1);
+        }
+        else if (u <= 0xFFFF)
+        {
+            put(0xCD, u, 2);
+        }
+        else if (u <= 0xFFFFFFFF)
+        {
+            put(0xCE, u, 4);
+        }
+        else
+        {
+            put(0xCF, u, 8);
+        }
+        return;
+    }
+
+    const auto n = j.get<std::int64_t>();
+    const auto bits = static_cast<std::uint64_t>(n);
+    if (n >= -32)
+    {
+        out.push_back(static_cast<std::uint8_t>(bits));
+    }
+    else if (n >= -128)
+    {
+        put(0xD0, bits, 1);
+    }
+    else if (n >= -32768)
+    {
+        put(0xD1, bits, 2);
+    }
+    else if (n >= -2147483648LL)
+    {
+        put(0xD2, bits, 4);
+    }
+    else
+    {
+        put(0xD3, bits, 8);
+    }
+}
+
+// integers at every boundary of the CBOR and MessagePack sizes, signed and
+// unsigned
+std::vector<json> boundary_integers()
+{
+    std::vector<json> result;
+    const std::array<std::uint64_t, 38> boundaries =
+    {
+        {
+            0, 1, 22, 23, 24, 25, 31, 32, 33, 126, 127, 128, 129, 254, 255, 256, 257,
+            32766, 32767, 32768, 32769, 65534, 65535, 65536, 65537,
+            2147483646ULL, 2147483647ULL, 2147483648ULL, 2147483649ULL,
+            4294967294ULL, 4294967295ULL, 4294967296ULL, 4294967297ULL,
+            9223372036854775806ULL, 9223372036854775807ULL, 9223372036854775808ULL,
+            18446744073709551614ULL, 18446744073709551615ULL
+        }
+    };
+    for (const std::uint64_t u : boundaries)
+    {
+        result.emplace_back(u);
+        if (u <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
+        {
+            const auto n = static_cast<std::int64_t>(u);
+            result.emplace_back(n);
+            result.emplace_back(-n);
+            result.emplace_back(-n - 1);
+        }
+    }
+    return result;
+}
+
+} // namespace
+
+// Arrays of integers are written in runs straight into space reserved from the
+// sink, with branch-free encodings; check them against independent encoders for
+// runs shorter and longer than one reservation, broken up by other values, and
+// through each sink.
+TEST_CASE("CBOR and MessagePack integer arrays")
+{
+    const std::vector<json> integers = boundary_integers();
+
+    for (const std::size_t length :
+            {
+                std::size_t{1}, std::size_t{27}, std::size_t{28}, std::size_t{29}, std::size_t{57}, std::size_t{1000}
+            })
+    {
+        for (const std::size_t break_every :
+                {
+                    std::size_t{0}, std::size_t{1}, std::size_t{7}, std::size_t{28}
+                })
+        {
+            CAPTURE(length)
+            CAPTURE(break_every)
+
+            json array = json::array();
+            std::vector<std::uint8_t> expected_cbor;
+            std::vector<std::uint8_t> expected_msgpack;
+            for (std::size_t i = 0; i < length; ++i)
+            {
+                if (break_every != 0 && i % (break_every + 1) == break_every)
+                {
+                    array.push_back("x");
+                    expected_cbor.push_back(0x61);
+                    expected_cbor.push_back('x');
+                    expected_msgpack.push_back(0xA1);
+                    expected_msgpack.push_back('x');
+                }
+                else
+                {
+                    const json& value = integers[(i * 7) % integers.size()];
+                    array.push_back(value);
+                    reference_cbor_integer(expected_cbor, value);
+                    reference_msgpack_integer(expected_msgpack, value);
+                }
+            }
+
+            std::vector<std::uint8_t> head;
+            reference_cbor_head(head, 0x80, length);
+            expected_cbor.insert(expected_cbor.begin(), head.begin(), head.end());
+
+            head.clear();
+            if (length <= 15)
+            {
+                head.push_back(static_cast<std::uint8_t>(0x90 + length));
+            }
+            else
+            {
+                head = {0xDC, static_cast<std::uint8_t>(length >> 8), static_cast<std::uint8_t>(length)};
+            }
+            expected_msgpack.insert(expected_msgpack.begin(), head.begin(), head.end());
+
+            CHECK(json::to_cbor(array) == expected_cbor);
+            CHECK(json::to_msgpack(array) == expected_msgpack);
+
+            std::vector<std::uint8_t> through_adapter = {0xAA};
+            json::to_cbor(array, through_adapter);
+            CHECK(std::vector<std::uint8_t>(through_adapter.begin() + 1, through_adapter.end()) == expected_cbor);
+            through_adapter = {0xAA};
+            json::to_msgpack(array, through_adapter);
+            CHECK(std::vector<std::uint8_t>(through_adapter.begin() + 1, through_adapter.end()) == expected_msgpack);
+
+            std::ostringstream stream;
+            json::to_cbor(array, stream);
+            std::string streamed = stream.str();
+            CHECK(std::vector<std::uint8_t>(streamed.begin(), streamed.end()) == expected_cbor);
+            stream.str("");
+            json::to_msgpack(array, stream);
+            streamed = stream.str();
+            CHECK(std::vector<std::uint8_t>(streamed.begin(), streamed.end()) == expected_msgpack);
+
+            CHECK(json::from_cbor(expected_cbor) == array);
+            CHECK(json::from_msgpack(expected_msgpack) == array);
+
+            // the same array as object members
+            const json object = {{"a", array}, {"b", array}};
+            CHECK(json::from_cbor(json::to_cbor(object)) == object);
+            CHECK(json::from_msgpack(json::to_msgpack(object)) == object);
+        }
+    }
+
+    // single values, outside an array
+    for (const auto& value : integers)
+    {
+        CAPTURE(value)
+        std::vector<std::uint8_t> expected;
+        reference_cbor_integer(expected, value);
+        CHECK(json::to_cbor(value) == expected);
+        expected.clear();
+        reference_msgpack_integer(expected, value);
+        CHECK(json::to_msgpack(value) == expected);
+    }
+}
+
 // binary_reserve_hint() is documented as a *lower* bound on the serialized size,
 // so that reserving it up front can never leave the returned vector holding
 // capacity beyond what the value actually needs.

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); // 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
+        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);
 
         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 iterator = typename base_type::iterator;
-    using Container = typename base_type::Container;
+    using typename base_type::iterator;
+    using typename base_type::Container;
     using base_type::base_type;
 
     template<typename... Args>

tests/src/unit-iterators1.cpp

@@ -1661,7 +1661,7 @@ TEST_CASE_TEMPLATE("reverse iteration and member access", Json, nlohmann::json,
         seen.clear();
         for (auto r = j.crbegin(); r != j.crend(); ++r)
         {
-            seen.push_back(r->template get<int>());
+            seen.push_back(*r);
         }
         CHECK(seen == std::vector<int> {4, 3, 2, 1});
     }

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); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed): reproducible
+        std::mt19937 gen(42);
         const std::string alphabet = "0123456789012345678901234567890123456789-+ ex";
         for (int i = 0; i < 5000; ++i)
         {
-            std::string token(gen() % 23, '0');
+            std::string token(static_cast<std::size_t>(gen() % 23), '0');
             for (auto& c : token)
             {
                 c = alphabet[gen() % alphabet.size()];

tests/src/unit-serialization.cpp

@@ -1374,13 +1374,7 @@ 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;
         }
@@ -1435,7 +1429,7 @@ 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", // NOLINT(bugprone-suspicious-missing-comma): "\xC3" "a" ends the hex escape
+        "\xC3" "a", "\xE2\x82" "\n", "\xE2\x82\"", "\xF0\x9F\x98\\", "\xC3\x7F", "\xC3\xC3\xA4", "\xE2\xF0\x9F\x98\x80",
         // truncated sequences
         "\xC3", "\xE2\x82", "\xF0\x9F\x98"
     };
@@ -1495,7 +1489,7 @@ 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 ? 17u : 8u));
+                        check_dump_against_reference(make_string(filler, pos, pattern, length - pos), bytes <= (filler.size() == 1 ? 17 : 8));
                     }
                 }
             }

tests/src/unit-testsuites.cpp

@@ -218,11 +218,7 @@ TEST_CASE("compliance tests from nativejson-benchmark")
             n1e308[0] = '[';
             n1e308[1] = '1';
             n1e308[310] = ']';
-#if JSON_STRICT_NUL_HANDLING
-            n1e308.resize(311); // 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");
@@ -94,10 +94,9 @@ 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) -> std::string
+        const auto patch_msg = [](const char* doc, const char* patch)
         {
             try
             {
@@ -106,23 +105,16 @@ 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) ",
-                // and with JSON_DIAGNOSTIC_POSITIONS its position like "(bytes 0-2) "; drop both
+                // with JSON_DIAGNOSTICS, what() names the offending value like "(/0) "; drop it
                 std::string msg = e.what();
-                for (const char* marker :
-            {
-                " (/", " (bytes "
-            })
+                const auto pos = msg.find(" (/");
+                if (pos != std::string::npos)
                 {
-                    const auto pos = msg.find(marker);
-                    if (pos != std::string::npos)
-                    {
-                        msg.erase(pos + 1, msg.find(") ", pos) - pos + 1);
-                    }
+                    msg.erase(pos + 1, msg.find(") ", pos) - pos + 1);
                 }
                 return msg;
             }
-            return {};
+            return std::string();
         };
 
         CHECK(patch_msg("{}", "{}") == "[json.exception.parse_error.104] parse error: JSON patch must be an array of objects");
@@ -140,5 +132,4 @@ 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
 }