Report the parse errors of the position test via SAX

The test caught json::parse_error, so it aborted in the ci_test_noexceptions build, where JSON_NOEXCEPTION turns the throw into std::abort(). sax_parse() hands the error position and the exception object to parse_error() without throwing, so the test now records them there and runs in every configuration. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Move the std::vector<std::byte> binary type tests out of unit-regression3
2026-10-13 09:47:12 +00:00 · 2026-10-13 11:22:48 +02:00 · 2026-10-13 09:40:36 +02:00 · 2026-10-13 08:52:49 +02:00
14 changed files with 399 additions and 257 deletions
@@ -610,8 +610,9 @@ foreach(SRC_FILE ${SRC_FILES})
    add_executable(single_${RELATIVE_SRC_FILE} EXCLUDE_FROM_ALL ${PROJECT_BINARY_DIR}/src_single/${RELATIVE_SRC_FILE}.cpp)
    target_include_directories(single_${RELATIVE_SRC_FILE} PRIVATE ${PROJECT_SOURCE_DIR}/include)
    target_compile_features(single_${RELATIVE_SRC_FILE} PRIVATE cxx_std_11)
-    if(RELATIVE_SRC_FILE STREQUAL "json")
-        # see below: report the diagnostics of json.hpp without --error, so they do not fail the build
+    if(RELATIVE_SRC_FILE STREQUAL "json" OR RELATIVE_SRC_FILE STREQUAL "json_literals")
+        # see below: report the diagnostics of json.hpp and json_literals.hpp without --error, so they
+        # do not fail the build
        set_property(TARGET single_${RELATIVE_SRC_FILE} PROPERTY CXX_INCLUDE_WHAT_YOU_USE ${IWYU_TOOL} -Xiwyu --max_line_length=300)
    else()
        set_property(TARGET single_${RELATIVE_SRC_FILE} PROPERTY CXX_INCLUDE_WHAT_YOU_USE "${iwyu_path_and_options}")
@@ -625,31 +626,18 @@ foreach(SRC_FILE ${SRC_FILES})
    # reporting its diagnostics (informational, via CXX_INCLUDE_WHAT_YOU_USE above) but exclude it
    # from the hard gate below so a fresh IWYU/compiler combination does not fail this target on a
    # nondeterministic suggestion for a header that already re-exports everything on purpose.
-    if(NOT RELATIVE_SRC_FILE STREQUAL "json")
+    # json_literals.hpp and json.hpp include each other on purpose (json.hpp includes it at its end
+    # unless JSON_NO_AUTOMATIC_UDLS is defined), and IWYU, not following the cycle, suggests replacing
+    # json.hpp with json_fwd.hpp although the literals need the complete basic_json; exclude it, too.
+    if(NOT RELATIVE_SRC_FILE STREQUAL "json" AND NOT RELATIVE_SRC_FILE STREQUAL "json_literals")
        list(APPEND single_binaries_tus src_single/${RELATIVE_SRC_FILE}.cpp)
    endif()
 endforeach()

-# The checks above look at each header on its own. Client code that includes only <nlohmann/json.hpp>
-# must not be told by include analyzers to include another nlohmann header for what it uses
-# (issue #5812): json.hpp marks those includes "IWYU pragma: export", and both IWYU and clang-tidy's
-# misc-include-cleaner (disabled in .clang-tidy for the library itself) check these clients.
-file(GLOB CONSUMER_FILES ${PROJECT_SOURCE_DIR}/tests/iwyu_consumer/*.cpp)
-foreach(CONSUMER_FILE ${CONSUMER_FILES})
-    get_filename_component(CONSUMER_NAME "${CONSUMER_FILE}" NAME_WE)
-    add_executable(iwyu_consumer_${CONSUMER_NAME} EXCLUDE_FROM_ALL ${CONSUMER_FILE})
-    target_include_directories(iwyu_consumer_${CONSUMER_NAME} PRIVATE ${PROJECT_SOURCE_DIR}/include)
-    target_compile_features(iwyu_consumer_${CONSUMER_NAME} PRIVATE cxx_std_11)
-    list(APPEND single_binaries iwyu_consumer_${CONSUMER_NAME})
-    list(APPEND single_binaries_tus ${CONSUMER_FILE})
-endforeach()
-
 if(IWYU_TOOL_PY)
    add_custom_target(ci_single_binaries
        DEPENDS ${single_binaries}
        COMMAND ${IWYU_TOOL_PY} -p ${PROJECT_BINARY_DIR} ${single_binaries_tus} -- ${iwyu_options}
-        COMMAND ${CLANG_TIDY_TOOL} -p ${PROJECT_BINARY_DIR} --checks=-*,misc-include-cleaner --warnings-as-errors=* ${CONSUMER_FILES}
-        VERBATIM
        COMMENT "Check if headers are self-contained"
    )
 else()
@@ -185,7 +185,9 @@ The lexer detects two optional extensions at compile time. Only `iterator_input_
 random-access input of single-byte characters:

 - `supports_seek`, `get_consumed_count()`, and `copy_consumed_range()` let the lexer reconstruct already consumed input
-  for error messages instead of copying every character it reads.
+  for error messages instead of copying every character it reads. With `get_read_count()` and
+  `count_consumed_lines()`, the lexer also derives the read position from the adapter and counts lines only when an
+  error needs them, instead of counting characters and lines on every read.
 - `supports_bulk_scan`, `bulk_data()`, `bulk_remaining()`, and `bulk_skip()` let the lexer scan strings directly in
  contiguous memory, several bytes at a time.

@@ -8,12 +8,12 @@

 #pragma once

-#include <algorithm> // min
+#include <algorithm> // count, find, min
 #include <array> // array
 #include <cstddef> // size_t
 #include <cstdint> // uint32_t
 #include <cstring> // strlen
-#include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next
+#include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next, reverse_iterator
 #include <streambuf> // streambuf
 #include <string> // string, char_traits
 #include <type_traits> // enable_if, is_base_of, is_pointer, is_integral, remove_pointer
@@ -297,6 +297,7 @@ class iterator_input_adapter
            return result;
        }

+        ++eof_reads;
        return char_traits<char_type>::eof();
    }

@@ -306,6 +307,26 @@ class iterator_input_adapter
        return static_cast<std::size_t>(std::distance(begin, current));
    }

+    // number of get_character() calls so far, including those that returned
+    // EOF; the lexer derives its position from it (see lexer::lazy_position)
+    std::size_t get_read_count() const
+    {
+        return get_consumed_count() + eof_reads;
+    }
+
+    // number of newlines in the consumed range [0, last_index); @a line_start
+    // is set to the index after the last of them (0 if there is none); only
+    // valid when supports_seek
+    std::size_t count_consumed_lines(std::size_t last_index, std::size_t& line_start) const
+    {
+        const auto to = std::next(begin, static_cast<typename std::iterator_traits<IteratorType>::difference_type>(last_index));
+        const auto newline = char_traits<char_type>::to_char_type('\n');
+        using reverse_it = std::reverse_iterator<IteratorType>;
+        const auto last_newline = std::find(reverse_it(to), reverse_it(begin), newline);
+        line_start = static_cast<std::size_t>(std::distance(begin, last_newline.base()));
+        return static_cast<std::size_t>(std::count(begin, last_newline.base(), newline));
+    }
+
    // append the already-consumed characters in the half-open range
    // [first_index, last_index) to @a out; only valid when supports_seek
    template<typename ContainerType>
@@ -422,6 +443,8 @@ class iterator_input_adapter
    IteratorType begin;
    IteratorType current;
    SentinelType end;
+    /// number of get_character() calls that returned EOF
+    std::size_t eof_reads = 0;

    template<typename BaseInputAdapter, size_t T>
    friend struct wide_string_input_helper;
@@ -217,7 +217,7 @@ struct diagnostic_positions
        {
            // Lexer has read the first character of the container, so
            // subtract 1 from the position to get the correct start position.
-            v.start_position = lexer->get_position() - 1;
+            v.start_position = lexer->get_chars_read_total() - 1;
        }
    }

@@ -231,7 +231,7 @@ struct diagnostic_positions
        if (lexer)
        {
            // Lexer's position is past the closing brace or bracket, so set that as the end position.
-            v.end_position = lexer->get_position();
+            v.end_position = lexer->get_chars_read_total();
        }
    }

@@ -247,7 +247,7 @@ struct diagnostic_positions
            // Lexer has read past the current field value, so set the end position to the current position.
            // The start position will be set below based on the length of the string representation
            // of the value.
-            v.end_position = lexer->get_position();
+            v.end_position = lexer->get_chars_read_total();

            switch (v.type())
            {
@@ -186,6 +186,15 @@ class lexer : public lexer_base<BasicJsonType>
    static constexpr bool lazy_token_string =
        input_adapter_supports_seek<InputAdapterType>(is_detected<detect_supports_seek, InputAdapterType> {});

+    /// whether the read position is derived from the input adapter on demand
+    /// instead of being counted on every scanned character. Seekable adapters
+    /// know how much input they consumed and can revisit it, so
+    /// chars_read_total is the adapter's read count (minus a pending unget),
+    /// and line and column are recomputed from the consumed input only when
+    /// get_position() is called (errors). Counting per character kept two
+    /// increments and a newline check in the hot path of every get().
+    static constexpr bool lazy_position = lazy_token_string;
+
    /// whether a simulated unget can be passed on to the input adapter, which
    /// then leaves the character in the input; see
    /// input_adapter_supports_lookahead
@@ -195,7 +204,9 @@ class lexer : public lexer_base<BasicJsonType>
    /// whether string scanning may bulk-consume runs of ordinary characters
    /// directly from a contiguous input buffer (SWAR fast path). This requires
    /// the token to be reconstructible lazily (lazy_token_string), so bypassing
-    /// the per-character capture in get() cannot lose error diagnostics.
+    /// the per-character capture in get() cannot lose error diagnostics. It
+    /// also implies lazy_position, so the bulk paths need not advance the
+    /// position counters.
    static constexpr bool bulk_scan =
        lazy_token_string
        && input_adapter_supports_bulk_scan<InputAdapterType>(is_detected<detect_supports_bulk_scan, InputAdapterType> {});
@@ -331,10 +342,6 @@ class lexer : public lexer_base<BasicJsonType>
        }
        token_buffer.append(reinterpret_cast<const typename string_t::value_type*>(data), pos);
        ia.bulk_skip(pos);
-        // the run contains no newline (all bytes < 0x20 are treated as special),
-        // so only the flat character counters advance
-        position.chars_read_total += pos;
-        position.chars_read_current_line += pos;
    }

    /// streaming input: no bulk fast path
@@ -1567,8 +1574,6 @@ scan_number_done:
            if (JSON_HEDLEY_LIKELY(integer_result != token_type::uninitialized))
            {
                ia.bulk_skip(len - 1);
-                position.chars_read_total += (len - 1);
-                position.chars_read_current_line += (len - 1);
                return integer_result;
            }
            // The value does not fit an integer, so this token converts as a
@@ -1585,8 +1590,6 @@ scan_number_done:
        decimal_point_position = dot_index;

        ia.bulk_skip(len - 1);
-        position.chars_read_total += (len - 1);
-        position.chars_read_current_line += (len - 1);

        return convert_number(number_type, mantissa_end);
    }
@@ -1637,7 +1640,7 @@ scan_number_done:

 #if JSON_DIAGNOSTIC_POSITIONS
        // the first character of the token has already been read, hence the -1
-        token_start_position = position.chars_read_total - 1;
+        token_start_position = get_chars_read_total() - 1;
 #endif

        note_token_start(std::integral_constant<bool, lazy_token_string> {});
@@ -1690,6 +1693,15 @@ scan_number_done:
    /// per-character position counters (line-count-on-'\n' bookkeeping is
    /// handled afterwards, in track_after_read(), once `current` is known)
    void advance_position() noexcept
+    {
+        advance_position_impl(std::integral_constant<bool, lazy_position> {});
+    }
+
+    /// seekable adapter: the position is derived from the adapter on demand
+    void advance_position_impl(std::true_type /*lazy*/) const noexcept {}
+
+    /// streaming adapter: count the character
+    void advance_position_impl(std::false_type /*lazy*/) noexcept
    {
        ++position.chars_read_total;
        ++position.chars_read_current_line;
@@ -1703,7 +1715,16 @@ scan_number_done:
        // seekable adapters reconstruct the token lazily on error (see
        // get_token_string), so the eager per-character copy is skipped
        capture_char(std::integral_constant<bool, lazy_token_string> {});
+        track_newline(std::integral_constant<bool, lazy_position> {});
+        return current;
+    }

+    /// seekable adapter: lines are counted on demand in get_position()
+    void track_newline(std::true_type /*lazy*/) const noexcept {}
+
+    /// streaming adapter: start a new line after reading a newline
+    void track_newline(std::false_type /*lazy*/) noexcept
+    {
        if (current == '\n')
        {
            ++position.lines_read;
@@ -1712,8 +1733,6 @@ scan_number_done:
            chars_read_before_newline = position.chars_read_current_line;
            position.chars_read_current_line = 0;
        }
-
-        return current;
    }

    /*!
@@ -1757,12 +1776,22 @@ scan_number_done:
    We implement unget by setting variable next_unget to true. The input is not
    changed - we just simulate ungetting by modifying chars_read_total,
    chars_read_current_line, and token_string. The next call to get() will
-    behave as if the unget character is read again.
+    behave as if the unget character is read again. With lazy_position, the
+    pending next_unget is all get_chars_read_total() needs.
    */
    void unget()
    {
        next_unget = true;
+        unget_position(std::integral_constant<bool, lazy_position> {});
+        uncapture_char(std::integral_constant<bool, lazy_token_string> {});
+    }

+    /// seekable adapter: get_chars_read_total() accounts for next_unget
+    void unget_position(std::true_type /*lazy*/) const noexcept {}
+
+    /// streaming adapter: step the counters back over the ungotten character
+    void unget_position(std::false_type /*lazy*/) noexcept
+    {
        --position.chars_read_total;

        // in case we "unget" a newline, we have to also decrement the lines_read
@@ -1785,8 +1814,6 @@ scan_number_done:
        {
            --position.chars_read_current_line;
        }
-
-        uncapture_char(std::integral_constant<bool, lazy_token_string> {});
    }

    /// adapter without lookahead: nothing to do (see release_lookahead)
@@ -1857,10 +1884,21 @@ scan_number_done:
    // diagnostics
    /////////////////////

-    /// return position of last read token
-    constexpr position_t get_position() const noexcept
+    /*!
+    @brief return the number of characters read so far
+
+    Unlike get_position(), this is O(1) for all adapters, so it may be called
+    for every value (JSON_DIAGNOSTIC_POSITIONS).
+    */
+    std::size_t get_chars_read_total() const noexcept
    {
-        return position;
+        return get_chars_read_total_impl(std::integral_constant<bool, lazy_position> {});
+    }
+
+    /// return position of last read token
+    position_t get_position() const
+    {
+        return get_position_impl(std::integral_constant<bool, lazy_position> {});
    }

    /*!
@@ -1897,6 +1935,43 @@ scan_number_done:
    }
 #endif

+  private:
+    /// seekable adapter: every get() either read from the adapter (including
+    /// reads at EOF, which get() counts as characters as well) or replayed an
+    /// ungotten character, so the count is the adapter's read count minus a
+    /// still pending unget
+    std::size_t get_chars_read_total_impl(std::true_type /*lazy*/) const noexcept
+    {
+        return ia.get_read_count() - (next_unget ? 1u : 0u);
+    }
+
+    /// streaming adapter: the counter is maintained by get() and unget()
+    std::size_t get_chars_read_total_impl(std::false_type /*lazy*/) const noexcept
+    {
+        return position.chars_read_total;
+    }
+
+    /// seekable adapter: count the lines in the consumed input; O(input read
+    /// so far), but only called on errors
+    position_t get_position_impl(std::true_type /*lazy*/) const
+    {
+        position_t result;
+        result.chars_read_total = get_chars_read_total();
+        // reads at EOF count as characters but are not part of the input
+        const std::size_t consumed = (std::min)(result.chars_read_total, ia.get_consumed_count());
+        std::size_t line_start = 0;
+        result.lines_read = ia.count_consumed_lines(consumed, line_start);
+        result.chars_read_current_line = result.chars_read_total - line_start;
+        return result;
+    }
+
+    /// streaming adapter: the position is maintained by get() and unget()
+    position_t get_position_impl(std::false_type /*lazy*/) const noexcept
+    {
+        return position;
+    }
+
+  public:
    /// seekable adapter: rebuild the last read token from the input on demand
    const std::vector<char_type>& collect_token_chars(std::vector<char_type>& out, std::true_type /*lazy*/) const
    {
@@ -2012,7 +2087,7 @@ scan_number_done:
    token_type scan()
    {
        // initially, skip the BOM
-        if (position.chars_read_total == 0 && !skip_bom())
+        if (get_chars_read_total() == 0 && !skip_bom())
        {
            error_message = "invalid BOM; must be 0xEF 0xBB 0xBF if given";
            return token_type::parse_error;
@@ -2039,7 +2114,7 @@ scan_number_done:
    token_type scan_expecting(token_type expected_type)
    {
        JSON_ASSERT(expected_type == token_type::name_separator || expected_type == token_type::value_separator);
-        JSON_ASSERT(position.chars_read_total > 0);
+        JSON_ASSERT(get_chars_read_total() > 0);
        const char_int_type expected_char = static_cast<unsigned char>((expected_type == token_type::name_separator) ? ':' : ',');
        skip_whitespace();
        if (JSON_HEDLEY_LIKELY(current == expected_char))
@@ -370,7 +370,7 @@ class parser
                    }
                    case token_type::end_of_input:
                    {
-                        if (JSON_HEDLEY_UNLIKELY(m_lexer.get_position().chars_read_total == 1))
+                        if (JSON_HEDLEY_UNLIKELY(m_lexer.get_chars_read_total() == 1))
                        {
                            return syntax_error(*sax, "attempting to parse an empty input; check that your input string or stream contains the expected JSON");
                        }
@@ -520,8 +520,10 @@ class parser
    {
        // MSVC 2015 reports C4100 (unreferenced parameter) when SAX::parse_error is static
        static_cast<void>(sax);
-        return sax.parse_error(m_lexer.get_position(), m_lexer.get_token_string(),
-                               parse_error::create(exception_id::syntax_error, m_lexer.get_position(), message, nullptr));
+        // computing the position is O(input read so far) for seekable input
+        const position_t position = m_lexer.get_position();
+        return sax.parse_error(position, m_lexer.get_token_string(),
+                               parse_error::create(exception_id::syntax_error, position, message, nullptr));
    }

    std::string exception_message(const token_type expected, const std::string& context)
@@ -42,14 +42,9 @@
 // each of these, not only the forward declarations from json_fwd.hpp, so IWYU's suggestion to
 // drop them (nothing in this file otherwise names the type) would break every downstream
 // translation unit that relies on basic_json<>'s defaults actually being usable.
-// export: client code names what these headers declare (nlohmann::json and ordered_json from
-// json_fwd.hpp, adl_serializer for specializations, json_ref behind brace initialization, the
-// NLOHMANN_DEFINE_* and NLOHMANN_JSON_NAMESPACE_* macros, and the literals at the end of this file), and include analyzers must
-// attribute it to this header, not tell clients to include the internal ones (issue #5812).
-// tests/iwyu_consumer checks this.
-#include <nlohmann/adl_serializer.hpp> // IWYU pragma: export
+#include <nlohmann/adl_serializer.hpp> // IWYU pragma: keep
 #include <nlohmann/byte_container_with_subtype.hpp>
-#include <nlohmann/detail/abi_macros.hpp> // IWYU pragma: export
+#include <nlohmann/detail/abi_macros.hpp>
 #include <nlohmann/detail/conversions/from_json.hpp> // IWYU pragma: keep
 #include <nlohmann/detail/conversions/to_json.hpp> // IWYU pragma: keep
 #include <nlohmann/detail/exceptions.hpp>
@@ -66,8 +61,8 @@
 #include <nlohmann/detail/iterators/primitive_iterator.hpp>
 #include <nlohmann/detail/json_custom_base_class.hpp>
 #include <nlohmann/detail/json_pointer.hpp>
-#include <nlohmann/detail/json_ref.hpp> // IWYU pragma: export
-#include <nlohmann/detail/macro_scope.hpp> // IWYU pragma: export
+#include <nlohmann/detail/json_ref.hpp>
+#include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/detected.hpp>
 #include <nlohmann/detail/string_concat.hpp>
 #include <nlohmann/detail/string_escape.hpp>
@@ -79,7 +74,7 @@
 #include <nlohmann/detail/output/serializer.hpp>
 #include <nlohmann/detail/recursion_depth_limit.hpp>
 #include <nlohmann/detail/value_t.hpp>
-#include <nlohmann/json_fwd.hpp> // IWYU pragma: export
+#include <nlohmann/json_fwd.hpp>
 #include <nlohmann/ordered_map.hpp> // IWYU pragma: keep
 #include <nlohmann/thirdparty/hedley/hedley.hpp>

@@ -7800,7 +7795,7 @@ struct formatter<nlohmann::NLOHMANN_BASIC_JSON_TPL, char> // NOLINT(cert-dcl58-c
 // where needed.
 #ifndef JSON_NO_AUTOMATIC_UDLS
    // NOLINTNEXTLINE(misc-header-include-cycle): json_literals.hpp includes this header
-    #include <nlohmann/json_literals.hpp> // IWYU pragma: export
+    #include <nlohmann/json_literals.hpp>
 #endif

 #endif  // INCLUDE_NLOHMANN_JSON_HPP_
@@ -42,11 +42,6 @@
 // each of these, not only the forward declarations from json_fwd.hpp, so IWYU's suggestion to
 // drop them (nothing in this file otherwise names the type) would break every downstream
 // translation unit that relies on basic_json<>'s defaults actually being usable.
-// export: client code names what these headers declare (nlohmann::json and ordered_json from
-// json_fwd.hpp, adl_serializer for specializations, json_ref behind brace initialization, the
-// NLOHMANN_DEFINE_* and NLOHMANN_JSON_NAMESPACE_* macros, and the literals at the end of this file), and include analyzers must
-// attribute it to this header, not tell clients to include the internal ones (issue #5812).
-// tests/iwyu_consumer checks this.
 // #include <nlohmann/adl_serializer.hpp>
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
@@ -7538,7 +7533,7 @@ struct adl_serializer
 };

 NLOHMANN_JSON_NAMESPACE_END
-// IWYU pragma: export
+// IWYU pragma: keep
 // #include <nlohmann/byte_container_with_subtype.hpp>
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
@@ -7646,7 +7641,7 @@ class byte_container_with_subtype : public BinaryType
 NLOHMANN_JSON_NAMESPACE_END

 // #include <nlohmann/detail/abi_macros.hpp>
-// IWYU pragma: export
+
 // #include <nlohmann/detail/conversions/from_json.hpp>
 // IWYU pragma: keep
 // #include <nlohmann/detail/conversions/to_json.hpp>
@@ -7968,12 +7963,12 @@ NLOHMANN_JSON_NAMESPACE_END



-#include <algorithm> // min
+#include <algorithm> // count, find, min
 #include <array> // array
 #include <cstddef> // size_t
 #include <cstdint> // uint32_t
 #include <cstring> // strlen
-#include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next
+#include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next, reverse_iterator
 #include <streambuf> // streambuf
 #include <string> // string, char_traits
 #include <type_traits> // enable_if, is_base_of, is_pointer, is_integral, remove_pointer
@@ -8262,6 +8257,7 @@ class iterator_input_adapter
            return result;
        }

+        ++eof_reads;
        return char_traits<char_type>::eof();
    }

@@ -8271,6 +8267,26 @@ class iterator_input_adapter
        return static_cast<std::size_t>(std::distance(begin, current));
    }

+    // number of get_character() calls so far, including those that returned
+    // EOF; the lexer derives its position from it (see lexer::lazy_position)
+    std::size_t get_read_count() const
+    {
+        return get_consumed_count() + eof_reads;
+    }
+
+    // number of newlines in the consumed range [0, last_index); @a line_start
+    // is set to the index after the last of them (0 if there is none); only
+    // valid when supports_seek
+    std::size_t count_consumed_lines(std::size_t last_index, std::size_t& line_start) const
+    {
+        const auto to = std::next(begin, static_cast<typename std::iterator_traits<IteratorType>::difference_type>(last_index));
+        const auto newline = char_traits<char_type>::to_char_type('\n');
+        using reverse_it = std::reverse_iterator<IteratorType>;
+        const auto last_newline = std::find(reverse_it(to), reverse_it(begin), newline);
+        line_start = static_cast<std::size_t>(std::distance(begin, last_newline.base()));
+        return static_cast<std::size_t>(std::count(begin, last_newline.base(), newline));
+    }
+
    // append the already-consumed characters in the half-open range
    // [first_index, last_index) to @a out; only valid when supports_seek
    template<typename ContainerType>
@@ -8387,6 +8403,8 @@ class iterator_input_adapter
    IteratorType begin;
    IteratorType current;
    SentinelType end;
+    /// number of get_character() calls that returned EOF
+    std::size_t eof_reads = 0;

    template<typename BaseInputAdapter, size_t T>
    friend struct wide_string_input_helper;
@@ -10589,6 +10607,15 @@ class lexer : public lexer_base<BasicJsonType>
    static constexpr bool lazy_token_string =
        input_adapter_supports_seek<InputAdapterType>(is_detected<detect_supports_seek, InputAdapterType> {});

+    /// whether the read position is derived from the input adapter on demand
+    /// instead of being counted on every scanned character. Seekable adapters
+    /// know how much input they consumed and can revisit it, so
+    /// chars_read_total is the adapter's read count (minus a pending unget),
+    /// and line and column are recomputed from the consumed input only when
+    /// get_position() is called (errors). Counting per character kept two
+    /// increments and a newline check in the hot path of every get().
+    static constexpr bool lazy_position = lazy_token_string;
+
    /// whether a simulated unget can be passed on to the input adapter, which
    /// then leaves the character in the input; see
    /// input_adapter_supports_lookahead
@@ -10598,7 +10625,9 @@ class lexer : public lexer_base<BasicJsonType>
    /// whether string scanning may bulk-consume runs of ordinary characters
    /// directly from a contiguous input buffer (SWAR fast path). This requires
    /// the token to be reconstructible lazily (lazy_token_string), so bypassing
-    /// the per-character capture in get() cannot lose error diagnostics.
+    /// the per-character capture in get() cannot lose error diagnostics. It
+    /// also implies lazy_position, so the bulk paths need not advance the
+    /// position counters.
    static constexpr bool bulk_scan =
        lazy_token_string
        && input_adapter_supports_bulk_scan<InputAdapterType>(is_detected<detect_supports_bulk_scan, InputAdapterType> {});
@@ -10734,10 +10763,6 @@ class lexer : public lexer_base<BasicJsonType>
        }
        token_buffer.append(reinterpret_cast<const typename string_t::value_type*>(data), pos);
        ia.bulk_skip(pos);
-        // the run contains no newline (all bytes < 0x20 are treated as special),
-        // so only the flat character counters advance
-        position.chars_read_total += pos;
-        position.chars_read_current_line += pos;
    }

    /// streaming input: no bulk fast path
@@ -11970,8 +11995,6 @@ scan_number_done:
            if (JSON_HEDLEY_LIKELY(integer_result != token_type::uninitialized))
            {
                ia.bulk_skip(len - 1);
-                position.chars_read_total += (len - 1);
-                position.chars_read_current_line += (len - 1);
                return integer_result;
            }
            // The value does not fit an integer, so this token converts as a
@@ -11988,8 +12011,6 @@ scan_number_done:
        decimal_point_position = dot_index;

        ia.bulk_skip(len - 1);
-        position.chars_read_total += (len - 1);
-        position.chars_read_current_line += (len - 1);

        return convert_number(number_type, mantissa_end);
    }
@@ -12040,7 +12061,7 @@ scan_number_done:

 #if JSON_DIAGNOSTIC_POSITIONS
        // the first character of the token has already been read, hence the -1
-        token_start_position = position.chars_read_total - 1;
+        token_start_position = get_chars_read_total() - 1;
 #endif

        note_token_start(std::integral_constant<bool, lazy_token_string> {});
@@ -12093,6 +12114,15 @@ scan_number_done:
    /// per-character position counters (line-count-on-'\n' bookkeeping is
    /// handled afterwards, in track_after_read(), once `current` is known)
    void advance_position() noexcept
+    {
+        advance_position_impl(std::integral_constant<bool, lazy_position> {});
+    }
+
+    /// seekable adapter: the position is derived from the adapter on demand
+    void advance_position_impl(std::true_type /*lazy*/) const noexcept {}
+
+    /// streaming adapter: count the character
+    void advance_position_impl(std::false_type /*lazy*/) noexcept
    {
        ++position.chars_read_total;
        ++position.chars_read_current_line;
@@ -12106,7 +12136,16 @@ scan_number_done:
        // seekable adapters reconstruct the token lazily on error (see
        // get_token_string), so the eager per-character copy is skipped
        capture_char(std::integral_constant<bool, lazy_token_string> {});
+        track_newline(std::integral_constant<bool, lazy_position> {});
+        return current;
+    }

+    /// seekable adapter: lines are counted on demand in get_position()
+    void track_newline(std::true_type /*lazy*/) const noexcept {}
+
+    /// streaming adapter: start a new line after reading a newline
+    void track_newline(std::false_type /*lazy*/) noexcept
+    {
        if (current == '\n')
        {
            ++position.lines_read;
@@ -12115,8 +12154,6 @@ scan_number_done:
            chars_read_before_newline = position.chars_read_current_line;
            position.chars_read_current_line = 0;
        }
-
-        return current;
    }

    /*!
@@ -12160,12 +12197,22 @@ scan_number_done:
    We implement unget by setting variable next_unget to true. The input is not
    changed - we just simulate ungetting by modifying chars_read_total,
    chars_read_current_line, and token_string. The next call to get() will
-    behave as if the unget character is read again.
+    behave as if the unget character is read again. With lazy_position, the
+    pending next_unget is all get_chars_read_total() needs.
    */
    void unget()
    {
        next_unget = true;
+        unget_position(std::integral_constant<bool, lazy_position> {});
+        uncapture_char(std::integral_constant<bool, lazy_token_string> {});
+    }

+    /// seekable adapter: get_chars_read_total() accounts for next_unget
+    void unget_position(std::true_type /*lazy*/) const noexcept {}
+
+    /// streaming adapter: step the counters back over the ungotten character
+    void unget_position(std::false_type /*lazy*/) noexcept
+    {
        --position.chars_read_total;

        // in case we "unget" a newline, we have to also decrement the lines_read
@@ -12188,8 +12235,6 @@ scan_number_done:
        {
            --position.chars_read_current_line;
        }
-
-        uncapture_char(std::integral_constant<bool, lazy_token_string> {});
    }

    /// adapter without lookahead: nothing to do (see release_lookahead)
@@ -12260,10 +12305,21 @@ scan_number_done:
    // diagnostics
    /////////////////////

-    /// return position of last read token
-    constexpr position_t get_position() const noexcept
+    /*!
+    @brief return the number of characters read so far
+
+    Unlike get_position(), this is O(1) for all adapters, so it may be called
+    for every value (JSON_DIAGNOSTIC_POSITIONS).
+    */
+    std::size_t get_chars_read_total() const noexcept
    {
-        return position;
+        return get_chars_read_total_impl(std::integral_constant<bool, lazy_position> {});
+    }
+
+    /// return position of last read token
+    position_t get_position() const
+    {
+        return get_position_impl(std::integral_constant<bool, lazy_position> {});
    }

    /*!
@@ -12300,6 +12356,43 @@ scan_number_done:
    }
 #endif

+  private:
+    /// seekable adapter: every get() either read from the adapter (including
+    /// reads at EOF, which get() counts as characters as well) or replayed an
+    /// ungotten character, so the count is the adapter's read count minus a
+    /// still pending unget
+    std::size_t get_chars_read_total_impl(std::true_type /*lazy*/) const noexcept
+    {
+        return ia.get_read_count() - (next_unget ? 1u : 0u);
+    }
+
+    /// streaming adapter: the counter is maintained by get() and unget()
+    std::size_t get_chars_read_total_impl(std::false_type /*lazy*/) const noexcept
+    {
+        return position.chars_read_total;
+    }
+
+    /// seekable adapter: count the lines in the consumed input; O(input read
+    /// so far), but only called on errors
+    position_t get_position_impl(std::true_type /*lazy*/) const
+    {
+        position_t result;
+        result.chars_read_total = get_chars_read_total();
+        // reads at EOF count as characters but are not part of the input
+        const std::size_t consumed = (std::min)(result.chars_read_total, ia.get_consumed_count());
+        std::size_t line_start = 0;
+        result.lines_read = ia.count_consumed_lines(consumed, line_start);
+        result.chars_read_current_line = result.chars_read_total - line_start;
+        return result;
+    }
+
+    /// streaming adapter: the position is maintained by get() and unget()
+    position_t get_position_impl(std::false_type /*lazy*/) const noexcept
+    {
+        return position;
+    }
+
+  public:
    /// seekable adapter: rebuild the last read token from the input on demand
    const std::vector<char_type>& collect_token_chars(std::vector<char_type>& out, std::true_type /*lazy*/) const
    {
@@ -12415,7 +12508,7 @@ scan_number_done:
    token_type scan()
    {
        // initially, skip the BOM
-        if (position.chars_read_total == 0 && !skip_bom())
+        if (get_chars_read_total() == 0 && !skip_bom())
        {
            error_message = "invalid BOM; must be 0xEF 0xBB 0xBF if given";
            return token_type::parse_error;
@@ -12442,7 +12535,7 @@ scan_number_done:
    token_type scan_expecting(token_type expected_type)
    {
        JSON_ASSERT(expected_type == token_type::name_separator || expected_type == token_type::value_separator);
-        JSON_ASSERT(position.chars_read_total > 0);
+        JSON_ASSERT(get_chars_read_total() > 0);
        const char_int_type expected_char = static_cast<unsigned char>((expected_type == token_type::name_separator) ? ':' : ',');
        skip_whitespace();
        if (JSON_HEDLEY_LIKELY(current == expected_char))
@@ -12796,7 +12889,7 @@ struct diagnostic_positions
        {
            // Lexer has read the first character of the container, so
            // subtract 1 from the position to get the correct start position.
-            v.start_position = lexer->get_position() - 1;
+            v.start_position = lexer->get_chars_read_total() - 1;
        }
    }

@@ -12810,7 +12903,7 @@ struct diagnostic_positions
        if (lexer)
        {
            // Lexer's position is past the closing brace or bracket, so set that as the end position.
-            v.end_position = lexer->get_position();
+            v.end_position = lexer->get_chars_read_total();
        }
    }

@@ -12826,7 +12919,7 @@ struct diagnostic_positions
            // Lexer has read past the current field value, so set the end position to the current position.
            // The start position will be set below based on the length of the string representation
            // of the value.
-            v.end_position = lexer->get_position();
+            v.end_position = lexer->get_chars_read_total();

            switch (v.type())
            {
@@ -18669,7 +18762,7 @@ class parser
                    }
                    case token_type::end_of_input:
                    {
-                        if (JSON_HEDLEY_UNLIKELY(m_lexer.get_position().chars_read_total == 1))
+                        if (JSON_HEDLEY_UNLIKELY(m_lexer.get_chars_read_total() == 1))
                        {
                            return syntax_error(*sax, "attempting to parse an empty input; check that your input string or stream contains the expected JSON");
                        }
@@ -18819,8 +18912,10 @@ class parser
    {
        // MSVC 2015 reports C4100 (unreferenced parameter) when SAX::parse_error is static
        static_cast<void>(sax);
-        return sax.parse_error(m_lexer.get_position(), m_lexer.get_token_string(),
-                               parse_error::create(exception_id::syntax_error, m_lexer.get_position(), message, nullptr));
+        // computing the position is O(input read so far) for seekable input
+        const position_t position = m_lexer.get_position();
+        return sax.parse_error(position, m_lexer.get_token_string(),
+                               parse_error::create(exception_id::syntax_error, position, message, nullptr));
    }

    std::string exception_message(const token_type expected, const std::string& context)
@@ -21415,9 +21510,9 @@ class json_ref

 }  // namespace detail
 NLOHMANN_JSON_NAMESPACE_END
-// IWYU pragma: export
+
 // #include <nlohmann/detail/macro_scope.hpp>
-// IWYU pragma: export
+
 // #include <nlohmann/detail/meta/detected.hpp>

 // #include <nlohmann/detail/string_concat.hpp>
@@ -27781,7 +27876,7 @@ NLOHMANN_JSON_NAMESPACE_END
 // #include <nlohmann/detail/value_t.hpp>

 // #include <nlohmann/json_fwd.hpp>
-// IWYU pragma: export
+
 // #include <nlohmann/ordered_map.hpp>
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
@@ -36214,7 +36309,7 @@ NLOHMANN_JSON_NAMESPACE_END
 #undef NLOHMANN_JSON_LITERAL_OPERATOR

 #endif  // INCLUDE_NLOHMANN_JSON_LITERALS_HPP_
-// IWYU pragma: export
+
 #endif

 #endif  // INCLUDE_NLOHMANN_JSON_HPP_
@@ -1,62 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  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
-
-// See values.cpp: the conversion macros and nlohmann::adl_serializer must be available through
-// <nlohmann/json.hpp> alone. NLOHMANN_JSON_SERIALIZE_ENUM (from the same header as
-// NLOHMANN_DEFINE_TYPE_INTRUSIVE) is left out: IWYU attributes the basic_json comparison in its
-// expansion to an unrelated standard header, the ambiguity described for json.hpp in cmake/ci.cmake.
-
-#include <string>
-
-#include <nlohmann/json.hpp>
-
-namespace ns
-{
-struct person
-{
-    std::string name;
-    int age;
-    NLOHMANN_DEFINE_TYPE_INTRUSIVE(person, name, age)
-};
-
-struct legacy
-{
-    int value;
-};
-} // namespace ns
-
-namespace nlohmann
-{
-template<>
-struct adl_serializer<ns::legacy>
-{
-    static void to_json(json& j, const ns::legacy& l)
-    {
-        j = l.value;
-    }
-
-    static void from_json(const json& j, ns::legacy& l)
-    {
-        l.value = j.get<int>();
-    }
-};
-} // namespace nlohmann
-
-int main()
-{
-    ns::person ada;
-    ada.name = "Ada";
-    ada.age = 36;
-    ns::legacy one;
-    one.value = 1;
-
-    const nlohmann::json j = ada;
-    const auto p = j.get<ns::person>();
-    const auto l = nlohmann::json(one).get<ns::legacy>();
-    return p.age - 36 + l.value - 1;
-}
@@ -1,19 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  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
-
-// See values.cpp: the user-defined literals must be available through <nlohmann/json.hpp> alone.
-
-#include <nlohmann/json.hpp>
-
-using namespace nlohmann::literals; // NOLINT(google-build-using-namespace)
-
-int main()
-{
-    const auto j = R"({"a": [1, 2]})"_json;
-    return j.at("/a/1"_json_pointer).get<int>() - 2;
-}
@@ -1,30 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  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
-
-// Uses the library the way a client does, including only <nlohmann/json.hpp>. ci_single_binaries
-// runs include-what-you-use and clang-tidy's misc-include-cleaner on this file and fails if either
-// asks for another nlohmann header, which would mean json.hpp does not export it (issue #5812).
-
-#include <cstdint>
-#include <string>
-#include <vector>
-
-#include <nlohmann/json.hpp>
-
-int main()
-{
-    // brace initialization (nlohmann::json, detail::json_ref)
-    nlohmann::json j = {{"pi", 3.141}, {"list", {1, 0, 2}}};
-    const nlohmann::ordered_json o = {{"b", 1}, {"a", 2}};
-
-    j["parsed"] = nlohmann::json::parse(R"({"happy": true})");
-    j["binary"] = nlohmann::json::binary(std::vector<std::uint8_t> {0xCA, 0xFE}, 42);
-
-    const std::string s = j.dump() + o.dump();
-    return s.empty() ? 1 : 0;
-}
@@ -8,6 +8,13 @@

 #include "doctest_compatibility.h"

+// capture whether JSON_DISABLE_ENUM_SERIALIZATION was enabled on the command
+// line before including json.hpp, which #undefs it; std::byte is an enum, so
+// converting std::vector<std::byte> needs enum serialization
+#if defined(JSON_DISABLE_ENUM_SERIALIZATION) && (JSON_DISABLE_ENUM_SERIALIZATION == 1)
+    #define SKIP_TESTS_FOR_ENUM_SERIALIZATION
+#endif
+
 #include <nlohmann/json.hpp>

 #include <cstdint>
@@ -85,3 +92,53 @@ TEST_CASE("binary type whose value type is not std::uint8_t")
    }
 #endif
 }
+
+#ifdef JSON_HAS_CPP_17
+// moved from unit-regression3.cpp, so that file does not instantiate a second
+// basic_json specialization (MinGW section limit, see windows.yml)
+TEST_CASE("std::vector<std::byte> as binary type")
+{
+    SECTION("issue #4804: from_cbor incompatible with std::vector<std::byte> as binary_t")
+    {
+        const std::vector<std::uint8_t> data = {0x80};
+        const auto decoded = byte_binary_json::from_cbor(data);
+        CHECK((decoded == byte_binary_json::array()));
+    }
+
+#ifndef SKIP_TESTS_FOR_ENUM_SERIALIZATION
+    SECTION("discussion #4209 - custom BinaryType direct assignment and round-tripping")
+    {
+        // Test that assigning a custom BinaryType directly creates a binary value, not an array
+        const std::vector<std::byte> original{std::byte{1}, std::byte{2}, std::byte{3}};
+        const byte_binary_json j = original;
+        CHECK(j.is_binary());
+        CHECK(!j.is_array());
+
+        // Test round-tripping: extracting the binary value back as the custom container type
+        const auto extracted = j.get<std::vector<std::byte>>();
+        CHECK(extracted == original);
+
+        // Test that the default json alias behavior is unchanged: std::vector<uint8_t> -> array
+        const nlohmann::json default_json = std::vector<std::uint8_t> {1, 2, 3};
+        CHECK(default_json.is_array());
+        CHECK(!default_json.is_binary());
+    }
+
+    SECTION("discussion #4209 - custom BinaryType extraction from parsed array")
+    {
+        // Test that extracting a custom BinaryType from a parsed JSON array still works
+        // (not just from a binary-typed node)
+        const auto j = byte_binary_json::parse("[1,2,3]");
+        CHECK(j.is_array());
+        CHECK(!j.is_binary());
+
+        // Extracting as custom BinaryType should work from arrays
+        const auto extracted = j.get<std::vector<std::byte>>();
+        CHECK(extracted.size() == 3);
+        CHECK(extracted[0] == std::byte{1});
+        CHECK(extracted[1] == std::byte{2});
+        CHECK(extracted[2] == std::byte{3});
+    }
+#endif
+}
+#endif
@@ -35,6 +35,7 @@ using nlohmann::json;
 #include <sstream>
 #include <string>
 #include <valarray>
+#include <vector>

 #include "sax_event_loggers.hpp"

@@ -1250,3 +1251,66 @@ TEST_CASE_TEMPLATE("deserialization of different character types (UTF-32)", T, c
    CHECK(json::sax_parse(v, &l));
    CHECK(l.events.size() == 1);
 }
+
+namespace
+{
+// records the position and message of a parse error; reporting the error via
+// SAX does not throw, so the test also runs with JSON_NOEXCEPTION
+struct SaxErrorRecorder : public SaxEventLogger
+{
+    bool parse_error(std::size_t position, const std::string& /*last_token*/, const json::exception& ex) override
+    {
+        error = std::to_string(position) + " " + ex.what();
+        return false;
+    }
+
+    std::string error {}; // NOLINT(readability-redundant-member-init)
+};
+} // namespace
+
+TEST_CASE("parse error positions are the same for contiguous and stream input")
+{
+    // contiguous input derives the position from the input on error, stream
+    // input counts it while reading (see lexer::lazy_position); the cases
+    // cover newlines before the error, ungetting a newline after a number,
+    // newlines inside a string, a comment, and reads at the end of input
+    struct test_case
+    {
+        std::string input;
+        std::size_t byte;
+        std::string message;
+    };
+    const std::vector<test_case> cases =
+    {
+        {"[\n  1,\n  2\n", 12, "[json.exception.parse_error.101] parse error at line 4, column 1: syntax error while parsing array - unexpected end of input; expected ']'"},
+        {"[1\n,2,\n]", 8, "[json.exception.parse_error.101] parse error at line 3, column 1: syntax error while parsing value - unexpected ']'; expected '[', '{', or a literal"},
+        {"[1\n x]", 5, "[json.exception.parse_error.101] parse error at line 2, column 2: syntax error while parsing array - invalid literal; last read: '1<U+000A> x'; expected ']'"},
+        {"1\n2", 3, "[json.exception.parse_error.101] parse error at line 2, column 1: syntax error while parsing value - unexpected number literal; expected end of input"},
+        {
+            "{\"a\":\n\"b\nc\"}", 9, R"([json.exception.parse_error.101] parse error at line 3, column 0: syntax error while parsing value - invalid string: control character U+000A (LF) must be escaped to \u000A or \n; last read: '"b<U+000A>')"
+        },
+        {"/* a\n b */\n x", 13, "[json.exception.parse_error.101] parse error at line 3, column 2: syntax error while parsing value - invalid literal; last read: '/* a<U+000A> b */<U+000A> x'"},
+        {"\n\n", 3, "[json.exception.parse_error.101] parse error at line 3, column 1: syntax error while parsing value - unexpected end of input; expected '[', '{', or a literal"},
+        {"[\"a\",\n 1e\n]", 10, "[json.exception.parse_error.101] parse error at line 3, column 0: syntax error while parsing value - invalid number; expected '+', '-', or digit after exponent; last read: '1e<U+000A>'"},
+        {"[tru\n]", 5, "[json.exception.parse_error.101] parse error at line 2, column 0: syntax error while parsing value - invalid literal; last read: '[tru<U+000A>'"},
+    };
+
+    for (const auto& c : cases)
+    {
+        CAPTURE(c.input)
+        const std::string expected = std::to_string(c.byte) + " " + c.message;
+
+        SaxErrorRecorder string_sax;
+        CHECK_FALSE(json::sax_parse(c.input, &string_sax, json::input_format_t::json, true, true));
+        CHECK(string_sax.error == expected);
+
+        SaxErrorRecorder pointer_sax;
+        CHECK_FALSE(json::sax_parse(c.input.data(), c.input.data() + c.input.size(), &pointer_sax, json::input_format_t::json, true, true));
+        CHECK(pointer_sax.error == expected);
+
+        std::istringstream is(c.input);
+        SaxErrorRecorder stream_sax;
+        CHECK_FALSE(json::sax_parse(is, &stream_sax, json::input_format_t::json, true, true));
+        CHECK(stream_sax.error == expected);
+    }
+}
@@ -58,11 +58,6 @@ using ordered_json = nlohmann::ordered_json;
        #include <optional>
    #elif __has_include(<experimental/optional>)
    #endif
-
-    /////////////////////////////////////////////////////////////////////
-    // for #4804
-    /////////////////////////////////////////////////////////////////////
-    using json_4804 = nlohmann::json::with_binary_t<std::vector<std::byte>>;
 #endif

 #ifdef JSON_HAS_CPP_20
@@ -458,49 +453,6 @@ TEST_CASE("regression tests 3")
 #endif

 #ifdef JSON_HAS_CPP_17
-    SECTION("issue #4804: from_cbor incompatible with std::vector<std::byte> as binary_t")
-    {
-        const std::vector<std::uint8_t> data = {0x80};
-        const auto decoded = json_4804::from_cbor(data);
-        CHECK((decoded == json_4804::array()));
-    }
-
-#ifndef SKIP_TESTS_FOR_ENUM_SERIALIZATION
-    SECTION("discussion #4209 - custom BinaryType direct assignment and round-tripping")
-    {
-        // Test that assigning a custom BinaryType directly creates a binary value, not an array
-        const std::vector<std::byte> original{std::byte{1}, std::byte{2}, std::byte{3}};
-        const json_4804 j = original;
-        CHECK(j.is_binary());
-        CHECK(!j.is_array());
-
-        // Test round-tripping: extracting the binary value back as the custom container type
-        const auto extracted = j.get<std::vector<std::byte>>();
-        CHECK(extracted == original);
-
-        // Test that the default json alias behavior is unchanged: std::vector<uint8_t> -> array
-        const json default_json = std::vector<std::uint8_t> {1, 2, 3};
-        CHECK(default_json.is_array());
-        CHECK(!default_json.is_binary());
-    }
-
-    SECTION("discussion #4209 - custom BinaryType extraction from parsed array")
-    {
-        // Test that extracting a custom BinaryType from a parsed JSON array still works
-        // (not just from a binary-typed node)
-        const auto j = json_4804::parse("[1,2,3]");
-        CHECK(j.is_array());
-        CHECK(!j.is_binary());
-
-        // Extracting as custom BinaryType should work from arrays
-        const auto extracted = j.get<std::vector<std::byte>>();
-        CHECK(extracted.size() == 3);
-        CHECK(extracted[0] == std::byte{1});
-        CHECK(extracted[1] == std::byte{2});
-        CHECK(extracted[2] == std::byte{3});
-    }
-#endif
-
    SECTION("issue #5046 - implicit conversion of return json to std::optional no longer implicit")
    {
        const json jval{};