Stricter fuzzer checks and boundary-value tests for buffers (#5774)

* Check in the fuzzers that parsing without exceptions agrees

Each fuzzer driver now also parses its input with allow_exceptions =
false. That call must never throw a parse_error, must return a discarded
value where parsing with exceptions fails, and must return the same value
where it succeeds. Values are compared by their dump(), because NaN is
not equal to itself.

A plain !is_discarded() assertion, as suggested in #3642, would never
fail: the drivers parse with exceptions, so a result can never be
discarded.

tests/fuzzing.md describes the checks and notes that OSS-Fuzz and
CIFuzz already run LeakSanitizer, because their default address
sanitizer includes it.

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

* Use JSON_HAS_RANGE_VIEW_CONVERSION in the range view regression tests

#5728 combined the JSON_HAS_RANGES and MinGW conditions into
JSON_HAS_RANGE_VIEW_CONVERSION, but three test guards still spelled
them out.

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

* Test the serializer's buffers at their boundaries

The dump() indent overflow survived full line coverage because the tests
grew its buffer by only one step. This adds tests that land exactly on,
and one past, the limits of the other two serializer buffers:

- write_buffer (1024 bytes): strings of 1023, 1024 and 1025 bytes at the
  top level, and of 1022 and 1023 bytes inside an array, so that both
  guards in put_string() are hit at their boundary. Each is checked for
  dump() and for stream output.
- string_buffer (512 bytes, flushed when fewer than 13 bytes remain):
  runs of two-byte escapes, and a surrogate pair written with 14 bytes of
  room, right after a flush, and one escape later.
- The 8-byte bulk scan from the serializer side: 0 to 17 plain bytes
  followed by a quote, a control character, or a non-ASCII character.

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

* Test the chunked string and binary reads of all binary formats

The binary readers read strings and binary values in chunks of 4096
bytes. Only CBOR tested lengths around that size. MessagePack, UBJSON,
BJData and BSON now round-trip lengths 0, 1, 4095, 4096, 4097, 8192 and
100000 from vector and pointer input, and must report a truncated
payload as a parse error.

UBJSON reads binary values as arrays of numbers, so it is tested with
strings only. BJData binary values reach the chunked read only in
Draft 3. BON8 decodes strings byte by byte and does not use this path.

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

---------

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

.github/CONTRIBUTING.md

@@ -205,6 +205,9 @@ API of the 3.x.y version is broken. This includes:
 - Changing access specifiers.
 - Changing default arguments.
 
+What is and is not covered by this guarantee is described in the
+[roadmap](https://json.nlohmann.me/community/roadmap/#api-stability).
+
 Although these guidelines may seem restrictive, they are essential for maintaining the library’s utility.
 
 Breaking changes may be introduced when they are guarded with a feature macro such as

.github/external_ci/appveyor.yml

@@ -87,9 +87,4 @@ build_script:
   - cmake --build . --config "%configuration%" --parallel 2
 
 test_script:
-  - if "%configuration%"=="Release" ctest -C "%configuration%" --parallel 2 --output-on-failure
-  # On Debug builds, skip test-unicode_all
-  # as it is extremely slow to run and cause
-  # occasional timeouts on AppVeyor.
-  # More info: https://github.com/nlohmann/json/pull/1570
-  - if "%configuration%"=="Debug" ctest --exclude-regex "test-unicode" -C "%configuration%" --parallel 2 --output-on-failure
+  - ctest -C "%configuration%" --parallel 2 --output-on-failure

.github/workflows/windows.yml

@@ -178,7 +178,7 @@ jobs:
       - name: Build
         run: cmake --build build --parallel 10
       - name: Test
-        run: cd build ; ctest -j 10 -C Debug --exclude-regex "test-unicode" --output-on-failure
+        run: cd build ; ctest -j 10 -C Debug --output-on-failure
 
   clang-cl-12:
     runs-on: windows-2022
@@ -195,7 +195,7 @@ jobs:
       - name: Build
         run: cmake --build build --config Debug --parallel 10
       - name: Test
-        run: cd build ; ctest -j 10 -C Debug --exclude-regex "test-unicode" --output-on-failure
+        run: cd build ; ctest -j 10 -C Debug --output-on-failure
 
   ci_module_cpp20:
     runs-on: windows-2022

README.md

@@ -7,7 +7,7 @@
 [![Coverage Status](https://coveralls.io/repos/github/nlohmann/json/badge.svg?branch=develop)](https://coveralls.io/github/nlohmann/json?branch=develop)
 [![Coverity Scan Build Status](https://scan.coverity.com/projects/5550/badge.svg)](https://scan.coverity.com/projects/nlohmann-json)
 [![Codacy Badge](https://app.codacy.com/project/badge/Grade/e0d1a9d5d6fd46fcb655c4cb930bb3e8)](https://app.codacy.com/gh/nlohmann/json/dashboard?utm_source=gh&utm_medium=referral&utm_content=&utm_campaign=Badge_grade)
-[![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/json.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:json)
+[![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/json.svg)](https://issues.oss-fuzz.com/issues?q=project:json)
 [![Try online](https://img.shields.io/badge/try-online-blue.svg)](https://wandbox.org/permlink/1mp10JbaANo6FUc7)
 [![Documentation](https://img.shields.io/badge/docs-mkdocs-blue.svg)](https://json.nlohmann.me)
 [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/nlohmann/json/develop/LICENSE.MIT)

cmake/ci.cmake

@@ -456,13 +456,14 @@ add_custom_target(ci_test_single_header
 # Valgrind.
 ###############################################################################
 
+# The Unicode test (~17M assertions) is too slow under Valgrind.
 add_custom_target(ci_test_valgrind
     COMMAND CXX=${GCC_TOOL} ${CMAKE_COMMAND}
         -DCMAKE_BUILD_TYPE=Debug -GNinja
         -DJSON_BuildTests=ON -DJSON_Valgrind=ON
         -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_valgrind
     COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_valgrind
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_valgrind && ${CMAKE_CTEST_COMMAND} -L valgrind --parallel ${N} --output-on-failure
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_valgrind && ${CMAKE_CTEST_COMMAND} -L valgrind --exclude-regex "test-unicode" --parallel ${N} --output-on-failure
     COMMENT "Compile and test with Valgrind"
 )
 
@@ -787,7 +788,7 @@ foreach(COMPILER g++-4.8 g++-4.9 g++-5 g++-6 g++-7 g++-8 g++-9 g++-10 g++-11 cla
                 -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_compiler_${COMPILER}
                 ${ADDITIONAL_FLAGS}
             COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_compiler_${COMPILER}
-            COMMAND cd ${PROJECT_BINARY_DIR}/build_compiler_${COMPILER} && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-unicode" --output-on-failure
+            COMMAND cd ${PROJECT_BINARY_DIR}/build_compiler_${COMPILER} && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
             COMMENT "Compile and test with ${COMPILER}"
         )
     endif()
@@ -801,7 +802,7 @@ add_custom_target(ci_test_compiler_default
         -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_compiler_default
         ${ADDITIONAL_FLAGS}
     COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_compiler_default --parallel ${N}
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_compiler_default && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-unicode" -LE git_required --output-on-failure
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_compiler_default && ${CMAKE_CTEST_COMMAND} --parallel ${N} -LE git_required --output-on-failure
     COMMENT "Compile and test with default C++ compiler"
 )
 
@@ -839,7 +840,7 @@ add_custom_target(ci_icpc
         -DJSON_BuildTests=ON -DJSON_FastTests=ON
         -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_icpc
     COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_icpc
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_icpc && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-unicode" --output-on-failure
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_icpc && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
     COMMENT "Compile and test with ICPC"
 )
 
@@ -850,7 +851,7 @@ add_custom_target(ci_icpx
         -DJSON_BuildTests=ON -DJSON_FastTests=ON
         -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_icpx
     COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_icpx
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_icpx && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-unicode" --output-on-failure
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_icpx && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
     COMMENT "Compile and test with ICPX (Intel oneAPI DPC++/C++)"
 )
 
@@ -886,7 +887,7 @@ add_custom_target(ci_nvhpc
     COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_nvhpc
     # the pipes are escaped so the surrounding shell passes them to ctest verbatim
     # instead of treating them as shell pipe operators
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_nvhpc && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-unicode\\|test-comparison_cpp20\\|test-comparison_legacy_cpp20\\|test-constructor1_cpp11\\|test-deserialization_cpp20" --output-on-failure
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_nvhpc && ${CMAKE_CTEST_COMMAND} --parallel ${N} --exclude-regex "test-comparison_cpp20\\|test-comparison_legacy_cpp20\\|test-constructor1_cpp11\\|test-deserialization_cpp20" --output-on-failure
     COMMENT "Compile and test with NVIDIA HPC SDK (nvc++)"
 )
 

docs/mkdocs/docs/api/basic_json/cbor_tag_handler_t.md

@@ -9,10 +9,10 @@ enum class cbor_tag_handler_t
 };
 ```
 
-This enumeration is used in the [`from_cbor`](from_cbor.md) function to choose how to treat tags:
+This enumeration is used in [`from_cbor`](from_cbor.md) and [`sax_parse`](sax_parse.md) to choose how to treat tags:
 
 error
-:   throw a `parse_error` exception in case of a tag
+:   report a parse error in case of a tag (the `from_cbor` overloads throw a `parse_error` exception by default)
 
 ignore
 :   ignore tags

docs/mkdocs/docs/api/basic_json/sax_parse.md

@@ -8,7 +8,8 @@ static bool sax_parse(InputType&& i,
                       input_format_t format = input_format_t::json,
                       const bool strict = true,
                       const bool ignore_comments = false,
-                      const bool ignore_trailing_commas = false);
+                      const bool ignore_trailing_commas = false,
+                      const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error);
 
 // (2)
 template<class IteratorType, class SAX, class SentinelType = IteratorType>
@@ -17,13 +18,14 @@ static bool sax_parse(IteratorType first, SentinelType last,
                       input_format_t format = input_format_t::json,
                       const bool strict = true,
                       const bool ignore_comments = false,
-                      const bool ignore_trailing_commas = false);
+                      const bool ignore_trailing_commas = false,
+                      const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error);
 ```
 
 Read from input and generate SAX events
 
 1. Read from a compatible input.
-2. Read from a pair of character iterators, or an iterator and a sentinel of a different type (C++20 ranges support)
+2. Read from a pair of character iterators, or an iterator and a sentinel of a different type (C++20 ranges support).
     
     The value_type of the iterator must be an integral type with a size of 1, 2, or 4 bytes, which will be interpreted
     respectively as UTF-8, UTF-16, and UTF-32. If `SentinelType` differs from `IteratorType`, it must be comparable to
@@ -82,6 +84,10 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
 :   whether trailing commas in arrays or objects should be ignored and treated like whitespace (`#!cpp true`) or yield a parse error
     (`#!cpp false`); (optional, `#!cpp false` by default)
 
+`tag_handler` (in)
+:   how to handle CBOR tags; see [`cbor_tag_handler_t`](cbor_tag_handler_t.md). Ignored for formats other than CBOR
+    (optional, `cbor_tag_handler_t::error` by default).
+
 `first` (in)
 :   iterator to the start of a character range
 
@@ -137,6 +143,7 @@ A UTF-8 byte order mark is silently ignored.
 - Added in version 3.2.0.
 - Ignoring comments via `ignore_comments` added in version 3.9.0.
 - Added `ignore_trailing_commas` in version 3.13.0.
+- Added `tag_handler` in version 3.13.0.
 - Extended container support (1) to include types with lvalue-only ADL `begin`/`end` (matching `std::begin`/`std::end` semantics) in version 3.13.0.
 - Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
 - `JSON_PRECISE_STREAM_POSITION` added in version 3.13.0 to optionally leave a `#!cpp std::istream` positioned right

docs/mkdocs/docs/api/macros/json_brace_init_copy_semantics.md

@@ -50,9 +50,11 @@ The default value is `0` (disabled — existing behavior is preserved).
     ```
 
     Code that relies on these producing arrays must use `json::array()` instead (see below). Lists with more than one
-    element, and a single `[string, value]` pair such as `{{"key", "value"}}`, which still creates an object, are not
-    affected. The library's own conversions are not affected either: for example, `std::tuple<int>{5}` still becomes
-    `[5]`.
+    element, and a single `[string, value]` pair *written as a braced list*, such as `{{"key", "value"}}`, which still
+    creates an object, are not affected. This exception is based on how the pair is written, not on the shape of its
+    value: an existing JSON value that happens to be a two-element array with a string as its first element, such as
+    `json arr = {"key", 42};`, is still copied by `json j{arr};` rather than turned into an object. The library's own
+    conversions are not affected either: for example, `std::tuple<int>{5}` still becomes `[5]`.
 
 !!! note "ABI compatibility"
 

docs/mkdocs/docs/community/roadmap.md

@@ -25,9 +25,7 @@ work items are tracked in the [GitHub milestones](https://github.com/nlohmann/js
 
 ## What the project will not do
 
-- **Break the public API of version 3.x.** See the
-  [contribution guidelines](https://github.com/nlohmann/json/blob/develop/.github/CONTRIBUTING.md#break-the-public-api)
-  for what counts as a breaking change.
+- **Break the public API of version 3.x.** See [API stability](#api-stability) for what this covers.
 - **Require a newer C++ standard than C++11.**
 - **Break JSON conformance** or enable non-standard extensions by default.
 - **Add dependencies** or require a build step. The library remains header-only, and the single header
@@ -35,6 +33,32 @@ work items are tracked in the [GitHub milestones](https://github.com/nlohmann/js
 - **Trade simplicity for speed or memory efficiency.** Performance improvements are welcome, but the library is not
   meant to compete with the fastest JSON libraries, see [Design goals](../home/design_goals.md).
 
+## API stability
+
+Releases follow [semantic versioning](https://semver.org): a minor or patch release of version 3.x does not break code
+that uses the public API. In particular, a 3.x release does not:
+
+- change the signature of a function (its parameter types, return type, number of parameters, or the const-ness of a
+  member function);
+- remove or rename a function or class;
+- change which exceptions a function throws, or the [exception ids](../home/exceptions.md);
+- change access specifiers or default arguments.
+
+Exceptions to these rules, for instance when fixing a bug requires changing the exception a function throws, are
+documented in the [release notes](../home/releases.md).
+
+The following are **not** part of the public API and may change in any release, including patch releases:
+
+- The text of exception messages returned by `what()`. Use the [exception id](../home/exceptions.md) to tell errors
+  apart.
+- The ABI, including `sizeof(basic_json)` and the memory layout of its values. Recompile your code when you upgrade the
+  library. The [versioned inline namespace](../features/namespace.md) turns mixing versions into a link error.
+- Everything in namespace `nlohmann::detail`, and macros and type traits that are not documented in the
+  [API reference](../api/basic_json/index.md).
+
+Changes that would break the public API are only added behind a macro whose default keeps the 3.x behavior, see
+[Version 4.0](#version-40).
+
 ## Version 4.0
 
 There is no release date for version 4.0 yet. Proposals that need a major version, for instance stricter type

docs/mkdocs/docs/features/binary_formats/cbor.md

@@ -131,6 +131,7 @@ The library maps CBOR types to JSON value types as follows:
 | Byte string            | binary          | 0x59       |
 | Byte string            | binary          | 0x5A       |
 | Byte string            | binary          | 0x5B       |
+| Byte string            | binary          | 0x5F       |
 | UTF-8 string           | string          | 0x60..0x77 |
 | UTF-8 string           | string          | 0x78       |
 | UTF-8 string           | string          | 0x79       |
@@ -156,6 +157,9 @@ The library maps CBOR types to JSON value types as follows:
 | Single-Precision Float | number_float    | 0xFA       |
 | Double-Precision Float | number_float    | 0xFB       |
 
+Indefinite-length UTF-8 strings (0x7F) and byte strings (0x5F) are supported. Each chunk must be a definite-length
+string of the same major type, as required by [RFC 8949, Section 3.2.3](https://www.rfc-editor.org/rfc/rfc8949.html#section-3.2.3).
+
 !!! warning "Incomplete mapping"
 
     The mapping is **incomplete** in the sense that not all CBOR types can be converted to a JSON value. The following CBOR types are not supported and will yield parse errors:

include/nlohmann/detail/conversions/to_json.hpp

@@ -13,7 +13,6 @@
     #include <optional> // optional
 #endif
 
-#include <algorithm> // copy
 #include <iterator> // begin, end
 #include <memory> // allocator_traits
 #include <string> //  basic_string, char_traits
@@ -39,10 +38,14 @@ namespace detail
 //////////////////
 
 /*
- * Note all external_constructor<>::construct functions need to call
- * j.m_data.m_value.destroy(j.m_data.m_type) to avoid a memory leak in case j contains an
- * allocated value (e.g., a string). See bug issue
+ * Note all external_constructor<>::construct functions need to store the new
+ * value with j.replace_value(), which destroys the old one to avoid a memory
+ * leak in case j contains an allocated value (e.g., a string). See bug issue
  * https://github.com/nlohmann/json/issues/2865 for more information.
+ *
+ * A value that has to be allocated is created before the old one is destroyed:
+ * were it the other way around, an exception while creating the new value would
+ * leave j with the type of the new value, but the pointer to the destroyed old one.
  */
 
 template<value_t> struct external_constructor;
@@ -53,10 +56,7 @@ struct external_constructor<value_t::boolean>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::boolean_t b) noexcept
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::boolean;
-        j.m_data.m_value = b;
-        j.assert_invariant();
+        j.replace_value(value_t::boolean, b);
     }
 };
 
@@ -66,19 +66,15 @@ struct external_constructor<value_t::string>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::string_t& s)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::string;
-        j.m_data.m_value = s;
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(s);
+        j.replace_value(value_t::string, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::string_t&& s)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::string;
-        j.m_data.m_value = std::move(s);
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(s));
+        j.replace_value(value_t::string, value);
     }
 
     template < typename BasicJsonType, typename CompatibleStringType,
@@ -86,10 +82,8 @@ struct external_constructor<value_t::string>
                              int > = 0 >
     static void construct(BasicJsonType& j, const CompatibleStringType& str)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::string;
-        j.m_data.m_value.string = j.template create<typename BasicJsonType::string_t>(str);
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::string_t>(str));
+        j.replace_value(value_t::string, value);
     }
 };
 
@@ -99,19 +93,15 @@ struct external_constructor<value_t::binary>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::binary_t& b)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::binary;
-        j.m_data.m_value = typename BasicJsonType::binary_t(b);
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(b);
+        j.replace_value(value_t::binary, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::binary_t&& b)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::binary;
-        j.m_data.m_value = typename BasicJsonType::binary_t(std::move(b));
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(b));
+        j.replace_value(value_t::binary, value);
     }
 };
 
@@ -121,10 +111,7 @@ struct external_constructor<value_t::number_float>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::number_float_t val) noexcept
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::number_float;
-        j.m_data.m_value = val;
-        j.assert_invariant();
+        j.replace_value(value_t::number_float, val);
     }
 };
 
@@ -134,10 +121,7 @@ struct external_constructor<value_t::number_unsigned>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::number_unsigned_t val) noexcept
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::number_unsigned;
-        j.m_data.m_value = val;
-        j.assert_invariant();
+        j.replace_value(value_t::number_unsigned, val);
     }
 };
 
@@ -147,10 +131,7 @@ struct external_constructor<value_t::number_integer>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::number_integer_t val) noexcept
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::number_integer;
-        j.m_data.m_value = val;
-        j.assert_invariant();
+        j.replace_value(value_t::number_integer, val);
     }
 };
 
@@ -160,21 +141,15 @@ struct external_constructor<value_t::array>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::array_t& arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = arr;
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(arr);
+        j.replace_value(value_t::array, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = std::move(arr);
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(arr));
+        j.replace_value(value_t::array, value);
     }
 
     template < typename BasicJsonType, typename CompatibleArrayType,
@@ -188,39 +163,23 @@ struct external_constructor<value_t::array>
         using std::begin;
         using std::end;
 
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr)));
+        j.replace_value(value_t::array, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const std::vector<bool>& arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = value_t::array;
-        j.m_data.m_value.array->reserve(arr.size());
-        for (const bool x : arr)
-        {
-            j.m_data.m_value.array->push_back(x);
-            j.set_parent(j.m_data.m_value.array->back());
-        }
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(arr.begin(), arr.end()));
+        j.replace_value(value_t::array, value);
     }
 
     template<typename BasicJsonType, typename T,
              enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
     static void construct(BasicJsonType& j, const std::valarray<T>& arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = value_t::array;
-        j.m_data.m_value.array->resize(arr.size());
-        std::copy(std::begin(arr), std::end(arr), j.m_data.m_value.array->begin());
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(std::begin(arr), std::end(arr)));
+        j.replace_value(value_t::array, value);
     }
 
 #if JSON_HAS_RANGE_VIEW_CONVERSION
@@ -228,18 +187,15 @@ struct external_constructor<value_t::array>
              enable_if_t<is_compatible_range_view<std::remove_cvref_t<CompatibleArrayType>>::value, int> = 0>
     static void construct(BasicJsonType& j, CompatibleArrayType && arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = value_t::array;
+        // no range constructor: a view's begin() and end() may have different
+        // types, and the view may only be iterable once
+        typename BasicJsonType::array_t elements;
         for (auto&& x : std::forward<CompatibleArrayType>(arr))
         {
-            j.m_data.m_value.array->push_back(x);
+            elements.push_back(x);
         }
-        // set the parents only once all elements are in place: a push_back
-        // that reallocates moves the earlier elements, which does not keep
-        // their parent pointers
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(elements));
+        j.replace_value(value_t::array, value);
     }
 #endif
 };
@@ -250,21 +206,15 @@ struct external_constructor<value_t::object>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::object_t& obj)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::object;
-        j.m_data.m_value = obj;
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(obj);
+        j.replace_value(value_t::object, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::object;
-        j.m_data.m_value = std::move(obj);
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(obj));
+        j.replace_value(value_t::object, value);
     }
 
     template < typename BasicJsonType, typename CompatibleObjectType,
@@ -274,11 +224,8 @@ struct external_constructor<value_t::object>
         using std::begin;
         using std::end;
 
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::object;
-        j.m_data.m_value.object = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj)));
+        j.replace_value(value_t::object, value);
     }
 };
 

include/nlohmann/detail/input/binary_reader.hpp

@@ -1072,6 +1072,20 @@ class binary_reader
         }
     }
 
+    /*!
+    @brief reports a nested indefinite-length CBOR string or byte array
+    @param[in] type_name  name of the rejected string type
+    @param[in] context  parsing context for the error message
+    @return whether the SAX consumer accepts the parse error
+    */
+    bool cbor_indefinite_string_error(const char* type_name, const char* context)
+    {
+        auto last_token = get_token_string();
+        return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read,
+                                exception_message(concat("indefinite-length ", type_name,
+                                        " is not allowed inside indefinite-length ", type_name, "; last byte: 0x", last_token), context), nullptr));
+    }
+
     /*!
     @brief reads a definite-length CBOR string
 
@@ -1081,12 +1095,13 @@ class binary_reader
     into the same string.
 
     @param[out] result  string the bytes are appended to
+    @param[in] inside_indefinite  whether the bytes belong to an indefinite-length string
 
     @return whether string creation completed
 
     @pre @a current is not EOF
     */
-    bool get_cbor_string_chunk(string_t& result)
+    bool get_cbor_string_chunk(string_t& result, const bool inside_indefinite)
     {
         switch (current)
         {
@@ -1147,7 +1162,7 @@ class binary_reader
             {
                 auto last_token = get_token_string();
                 return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read,
-                                        exception_message(concat("expected length specification (0x60-0x7B) or indefinite string type (0x7F); last byte: 0x", last_token), "string"), nullptr));
+                                        exception_message(concat("expected length specification (0x60-0x7B)", inside_indefinite ? "" : " or indefinite string type (0x7F)", "; last byte: 0x", last_token), "string"), nullptr));
             }
         }
     }
@@ -1165,13 +1180,9 @@ class binary_reader
     */
     bool get_cbor_string(string_t& result, const char* context = "string")
     {
-        // number of indefinite-length strings that have been opened and not
-        // closed yet. RFC 8949, Section 3.2.3 does not permit nesting them,
-        // but this reader has always accepted it, so the open levels are
-        // counted instead of recursed through, which overflowed the stack for
-        // an input of repeated 0x7F bytes (see #5104). Every chunk is appended
-        // to the same result, so no per-level state is needed.
-        std::size_t open = 0;
+        // read chunks iteratively, but reject a second indefinite-length
+        // level as required by RFC 8949, Section 3.2.3
+        bool indefinite = false;
 
         while (true)
         {
@@ -1182,29 +1193,28 @@ class binary_reader
 
             if (current == 0x7F) // UTF-8 string (indefinite length)
             {
-                ++open;
-                get();
-                continue;
-            }
-
-            // a break marker closes the innermost indefinite-length string;
-            // outside of one it is not a string and falls through to the error
-            if (open != 0 && current == 0xFF)
-            {
-                if (--open == 0)
+                if (JSON_HEDLEY_UNLIKELY(indefinite))
                 {
-                    return check_string_utf8(result, context);
+                    return cbor_indefinite_string_error("string", "string");
                 }
+                indefinite = true;
                 get();
                 continue;
             }
 
-            if (JSON_HEDLEY_UNLIKELY(!get_cbor_string_chunk(result)))
+            // a break marker closes the indefinite-length string; outside
+            // of one it falls through to the error below
+            if (indefinite && current == 0xFF)
+            {
+                return check_string_utf8(result, context);
+            }
+
+            if (JSON_HEDLEY_UNLIKELY(!get_cbor_string_chunk(result, indefinite)))
             {
                 return false;
             }
 
-            if (open == 0)
+            if (!indefinite)
             {
                 return check_string_utf8(result, context);
             }
@@ -1296,12 +1306,13 @@ class binary_reader
     read into the same byte array.
 
     @param[out] result  byte array the bytes are appended to
+    @param[in] inside_indefinite  whether the bytes belong to an indefinite-length string
 
     @return whether byte array creation completed
 
     @pre @a current is not EOF
     */
-    bool get_cbor_binary_chunk(binary_t& result)
+    bool get_cbor_binary_chunk(binary_t& result, const bool inside_indefinite)
     {
         switch (current)
         {
@@ -1366,7 +1377,7 @@ class binary_reader
             {
                 auto last_token = get_token_string();
                 return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read,
-                                        exception_message(concat("expected length specification (0x40-0x5B) or indefinite binary array type (0x5F); last byte: 0x", last_token), "binary"), nullptr));
+                                        exception_message(concat("expected length specification (0x40-0x5B)", inside_indefinite ? "" : " or indefinite binary array type (0x5F)", "; last byte: 0x", last_token), "binary"), nullptr));
             }
         }
     }
@@ -1384,9 +1395,9 @@ class binary_reader
     */
     bool get_cbor_binary(binary_t& result)
     {
-        // the open indefinite-length byte arrays are counted rather than
-        // recursed through, for the reason given in @ref get_cbor_string
-        std::size_t open = 0;
+        // read chunks iteratively, but reject a second indefinite-length
+        // level as required by RFC 8949, Section 3.2.3
+        bool indefinite = false;
 
         while (true)
         {
@@ -1397,29 +1408,28 @@ class binary_reader
 
             if (current == 0x5F) // Binary data (indefinite length)
             {
-                ++open;
-                get();
-                continue;
-            }
-
-            // a break marker closes the innermost indefinite-length byte
-            // array; outside of one it falls through to the error below
-            if (open != 0 && current == 0xFF)
-            {
-                if (--open == 0)
+                if (JSON_HEDLEY_UNLIKELY(indefinite))
                 {
-                    return true;
+                    return cbor_indefinite_string_error("binary array", "binary");
                 }
+                indefinite = true;
                 get();
                 continue;
             }
 
-            if (JSON_HEDLEY_UNLIKELY(!get_cbor_binary_chunk(result)))
+            // a break marker closes the indefinite-length string; outside
+            // of one it falls through to the error below
+            if (indefinite && current == 0xFF)
+            {
+                return true;
+            }
+
+            if (JSON_HEDLEY_UNLIKELY(!get_cbor_binary_chunk(result, indefinite)))
             {
                 return false;
             }
 
-            if (open == 0)
+            if (!indefinite)
             {
                 return true;
             }

include/nlohmann/detail/json_ref.hpp

@@ -34,6 +34,7 @@ class json_ref
 
     json_ref(std::initializer_list<json_ref> init)
         : owned_value(init)
+        , braced_list(true)
     {}
 
     template <
@@ -69,9 +70,17 @@ class json_ref
         return &** this;
     }
 
+    /// whether the value was written as a braced list, such as {"key", 1},
+    /// rather than given as a value
+    bool is_braced_list() const noexcept
+    {
+        return braced_list;
+    }
+
   private:
     mutable value_type owned_value = nullptr;
     value_type const* value_ref = nullptr;
+    bool braced_list = false;
 };
 
 }  // namespace detail

include/nlohmann/json.hpp

@@ -676,6 +676,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         /// constructor for rvalue binary arrays (internal type)
         json_value(binary_t&& value) : binary(create<binary_t>(std::move(value))) {}
 
+        /// constructors taking ownership of an already created value
+        explicit json_value(string_t* value) noexcept : string(value) {}
+        explicit json_value(object_t* value) noexcept : object(value) {}
+        explicit json_value(array_t* value) noexcept : array(value) {}
+
 private:
         // raw, allocation-free transfer of m_data from src to dst: no
         // set_parents()/assert_invariant() (the former is O(#children) per
@@ -1006,6 +1011,18 @@ public:
 #endif
     }
 
+    /// @brief replace the stored value with an already created one
+    /// The new value must be created before calling this function: if its
+    /// creation throws, the current value is left untouched.
+    void replace_value(value_t t, const json_value& v) noexcept
+    {
+        m_data.m_value.destroy(m_data.m_type);
+        m_data.m_value = v;
+        m_data.m_type = t;
+        set_parents();
+        assert_invariant();
+    }
+
     iterator set_parents(iterator it, std::ptrdiff_t count_set_parents)
     {
 #if JSON_DIAGNOSTICS
@@ -2235,6 +2252,18 @@ public:
                bool type_deduction = true,
                value_t manual_type = value_t::array)
     {
+#if JSON_BRACE_INIT_COPY_SEMANTICS
+        // a single element that is a value rather than a braced list is
+        // copied or moved as is, whatever its content looks like
+        if (type_deduction && init.size() == 1 && !init.begin()->is_braced_list())
+        {
+            *this = init.begin()->moved_or_copied();
+            set_parents();
+            assert_invariant();
+            return;
+        }
+#endif
+
         // check if each element is an array with two elements whose first
         // element is a string
         bool is_an_object = std::all_of(init.begin(), init.end(),
@@ -2265,8 +2294,8 @@ public:
         if (is_an_object)
         {
             // the initializer list is a list of pairs -> create an object
-            m_data.m_type = value_t::object;
             m_data.m_value = value_t::object;
+            m_data.m_type = value_t::object;
 
             for (auto& element_ref : init)
             {
@@ -2288,8 +2317,8 @@ public:
             }
 #endif
             // the initializer list describes an array -> create an array
-            m_data.m_type = value_t::array;
             m_data.m_value.array = create<array_t>(init.begin(), init.end());
+            m_data.m_type = value_t::array;
         }
 
         set_parents();
@@ -2302,8 +2331,8 @@ public:
     static basic_json binary(const typename binary_t::container_type& init)
     {
         auto res = basic_json();
-        res.m_data.m_type = value_t::binary;
         res.m_data.m_value = init;
+        res.m_data.m_type = value_t::binary;
         return res;
     }
 
@@ -2313,8 +2342,8 @@ public:
     static basic_json binary(const typename binary_t::container_type& init, typename binary_t::subtype_type subtype)
     {
         auto res = basic_json();
-        res.m_data.m_type = value_t::binary;
         res.m_data.m_value = binary_t(init, subtype);
+        res.m_data.m_type = value_t::binary;
         return res;
     }
 
@@ -2324,8 +2353,8 @@ public:
     static basic_json binary(typename binary_t::container_type&& init)
     {
         auto res = basic_json();
-        res.m_data.m_type = value_t::binary;
         res.m_data.m_value = std::move(init);
+        res.m_data.m_type = value_t::binary;
         return res;
     }
 
@@ -2335,8 +2364,8 @@ public:
     static basic_json binary(typename binary_t::container_type&& init, typename binary_t::subtype_type subtype)
     {
         auto res = basic_json();
-        res.m_data.m_type = value_t::binary;
         res.m_data.m_value = binary_t(std::move(init), subtype);
+        res.m_data.m_type = value_t::binary;
         return res;
     }
 
@@ -5654,12 +5683,13 @@ public:
                           input_format_t format = input_format_t::json,
                           const bool strict = true,
                           const bool ignore_comments = false,
-                          const bool ignore_trailing_commas = false)
+                          const bool ignore_trailing_commas = false,
+                          const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
     {
         auto ia = detail::input_adapter(std::forward<InputType>(i));
         return format == input_format_t::json
                ? parser(std::move(ia), nullptr, true, ignore_comments, ignore_trailing_commas).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict, tag_handler);
     }
 
     /// @brief generate SAX events (iterator pair, or iterator+sentinel pair for C++20 ranges support)
@@ -5671,12 +5701,13 @@ public:
                           input_format_t format = input_format_t::json,
                           const bool strict = true,
                           const bool ignore_comments = false,
-                          const bool ignore_trailing_commas = false)
+                          const bool ignore_trailing_commas = false,
+                          const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
     {
         auto ia = detail::input_adapter(std::move(first), std::move(last));
         return format == input_format_t::json
                ? parser(std::move(ia), nullptr, true, ignore_comments, ignore_trailing_commas).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict, tag_handler);
     }
 
     /// @brief generate SAX events
@@ -5704,7 +5735,8 @@ public:
                           input_format_t format = input_format_t::json,
                           const bool strict = true,
                           const bool ignore_comments = false,
-                          const bool ignore_trailing_commas = false)
+                          const bool ignore_trailing_commas = false,
+                          const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
 #if JSON_DELETE_DEPRECATED_FUNCTIONS
     = delete;
 #else
@@ -5714,7 +5746,7 @@ public:
                // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
                ? parser(std::move(ia), nullptr, true, ignore_comments, ignore_trailing_commas).sax_parse(sax, strict)
                // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
-               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict, tag_handler);
     }
 #endif
 #if defined(__clang__)

single_include/nlohmann/json.hpp

@@ -6193,7 +6193,6 @@ NLOHMANN_JSON_NAMESPACE_END
     #include <optional> // optional
 #endif
 
-#include <algorithm> // copy
 #include <iterator> // begin, end
 #include <memory> // allocator_traits
 #include <string> //  basic_string, char_traits
@@ -6833,10 +6832,14 @@ namespace detail
 //////////////////
 
 /*
- * Note all external_constructor<>::construct functions need to call
- * j.m_data.m_value.destroy(j.m_data.m_type) to avoid a memory leak in case j contains an
- * allocated value (e.g., a string). See bug issue
+ * Note all external_constructor<>::construct functions need to store the new
+ * value with j.replace_value(), which destroys the old one to avoid a memory
+ * leak in case j contains an allocated value (e.g., a string). See bug issue
  * https://github.com/nlohmann/json/issues/2865 for more information.
+ *
+ * A value that has to be allocated is created before the old one is destroyed:
+ * were it the other way around, an exception while creating the new value would
+ * leave j with the type of the new value, but the pointer to the destroyed old one.
  */
 
 template<value_t> struct external_constructor;
@@ -6847,10 +6850,7 @@ struct external_constructor<value_t::boolean>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::boolean_t b) noexcept
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::boolean;
-        j.m_data.m_value = b;
-        j.assert_invariant();
+        j.replace_value(value_t::boolean, b);
     }
 };
 
@@ -6860,19 +6860,15 @@ struct external_constructor<value_t::string>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::string_t& s)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::string;
-        j.m_data.m_value = s;
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(s);
+        j.replace_value(value_t::string, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::string_t&& s)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::string;
-        j.m_data.m_value = std::move(s);
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(s));
+        j.replace_value(value_t::string, value);
     }
 
     template < typename BasicJsonType, typename CompatibleStringType,
@@ -6880,10 +6876,8 @@ struct external_constructor<value_t::string>
                              int > = 0 >
     static void construct(BasicJsonType& j, const CompatibleStringType& str)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::string;
-        j.m_data.m_value.string = j.template create<typename BasicJsonType::string_t>(str);
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::string_t>(str));
+        j.replace_value(value_t::string, value);
     }
 };
 
@@ -6893,19 +6887,15 @@ struct external_constructor<value_t::binary>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::binary_t& b)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::binary;
-        j.m_data.m_value = typename BasicJsonType::binary_t(b);
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(b);
+        j.replace_value(value_t::binary, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::binary_t&& b)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::binary;
-        j.m_data.m_value = typename BasicJsonType::binary_t(std::move(b));
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(b));
+        j.replace_value(value_t::binary, value);
     }
 };
 
@@ -6915,10 +6905,7 @@ struct external_constructor<value_t::number_float>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::number_float_t val) noexcept
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::number_float;
-        j.m_data.m_value = val;
-        j.assert_invariant();
+        j.replace_value(value_t::number_float, val);
     }
 };
 
@@ -6928,10 +6915,7 @@ struct external_constructor<value_t::number_unsigned>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::number_unsigned_t val) noexcept
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::number_unsigned;
-        j.m_data.m_value = val;
-        j.assert_invariant();
+        j.replace_value(value_t::number_unsigned, val);
     }
 };
 
@@ -6941,10 +6925,7 @@ struct external_constructor<value_t::number_integer>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::number_integer_t val) noexcept
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::number_integer;
-        j.m_data.m_value = val;
-        j.assert_invariant();
+        j.replace_value(value_t::number_integer, val);
     }
 };
 
@@ -6954,21 +6935,15 @@ struct external_constructor<value_t::array>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::array_t& arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = arr;
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(arr);
+        j.replace_value(value_t::array, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = std::move(arr);
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(arr));
+        j.replace_value(value_t::array, value);
     }
 
     template < typename BasicJsonType, typename CompatibleArrayType,
@@ -6982,39 +6957,23 @@ struct external_constructor<value_t::array>
         using std::begin;
         using std::end;
 
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr)));
+        j.replace_value(value_t::array, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const std::vector<bool>& arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = value_t::array;
-        j.m_data.m_value.array->reserve(arr.size());
-        for (const bool x : arr)
-        {
-            j.m_data.m_value.array->push_back(x);
-            j.set_parent(j.m_data.m_value.array->back());
-        }
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(arr.begin(), arr.end()));
+        j.replace_value(value_t::array, value);
     }
 
     template<typename BasicJsonType, typename T,
              enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
     static void construct(BasicJsonType& j, const std::valarray<T>& arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = value_t::array;
-        j.m_data.m_value.array->resize(arr.size());
-        std::copy(std::begin(arr), std::end(arr), j.m_data.m_value.array->begin());
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(std::begin(arr), std::end(arr)));
+        j.replace_value(value_t::array, value);
     }
 
 #if JSON_HAS_RANGE_VIEW_CONVERSION
@@ -7022,18 +6981,15 @@ struct external_constructor<value_t::array>
              enable_if_t<is_compatible_range_view<std::remove_cvref_t<CompatibleArrayType>>::value, int> = 0>
     static void construct(BasicJsonType& j, CompatibleArrayType && arr)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::array;
-        j.m_data.m_value = value_t::array;
+        // no range constructor: a view's begin() and end() may have different
+        // types, and the view may only be iterable once
+        typename BasicJsonType::array_t elements;
         for (auto&& x : std::forward<CompatibleArrayType>(arr))
         {
-            j.m_data.m_value.array->push_back(x);
+            elements.push_back(x);
         }
-        // set the parents only once all elements are in place: a push_back
-        // that reallocates moves the earlier elements, which does not keep
-        // their parent pointers
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(elements));
+        j.replace_value(value_t::array, value);
     }
 #endif
 };
@@ -7044,21 +7000,15 @@ struct external_constructor<value_t::object>
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const typename BasicJsonType::object_t& obj)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::object;
-        j.m_data.m_value = obj;
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(obj);
+        j.replace_value(value_t::object, value);
     }
 
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
     {
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::object;
-        j.m_data.m_value = std::move(obj);
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(std::move(obj));
+        j.replace_value(value_t::object, value);
     }
 
     template < typename BasicJsonType, typename CompatibleObjectType,
@@ -7068,11 +7018,8 @@ struct external_constructor<value_t::object>
         using std::begin;
         using std::end;
 
-        j.m_data.m_value.destroy(j.m_data.m_type);
-        j.m_data.m_type = value_t::object;
-        j.m_data.m_value.object = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
-        j.set_parents();
-        j.assert_invariant();
+        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj)));
+        j.replace_value(value_t::object, value);
     }
 };
 
@@ -14821,6 +14768,20 @@ class binary_reader
         }
     }
 
+    /*!
+    @brief reports a nested indefinite-length CBOR string or byte array
+    @param[in] type_name  name of the rejected string type
+    @param[in] context  parsing context for the error message
+    @return whether the SAX consumer accepts the parse error
+    */
+    bool cbor_indefinite_string_error(const char* type_name, const char* context)
+    {
+        auto last_token = get_token_string();
+        return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read,
+                                exception_message(concat("indefinite-length ", type_name,
+                                        " is not allowed inside indefinite-length ", type_name, "; last byte: 0x", last_token), context), nullptr));
+    }
+
     /*!
     @brief reads a definite-length CBOR string
 
@@ -14830,12 +14791,13 @@ class binary_reader
     into the same string.
 
     @param[out] result  string the bytes are appended to
+    @param[in] inside_indefinite  whether the bytes belong to an indefinite-length string
 
     @return whether string creation completed
 
     @pre @a current is not EOF
     */
-    bool get_cbor_string_chunk(string_t& result)
+    bool get_cbor_string_chunk(string_t& result, const bool inside_indefinite)
     {
         switch (current)
         {
@@ -14896,7 +14858,7 @@ class binary_reader
             {
                 auto last_token = get_token_string();
                 return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read,
-                                        exception_message(concat("expected length specification (0x60-0x7B) or indefinite string type (0x7F); last byte: 0x", last_token), "string"), nullptr));
+                                        exception_message(concat("expected length specification (0x60-0x7B)", inside_indefinite ? "" : " or indefinite string type (0x7F)", "; last byte: 0x", last_token), "string"), nullptr));
             }
         }
     }
@@ -14914,13 +14876,9 @@ class binary_reader
     */
     bool get_cbor_string(string_t& result, const char* context = "string")
     {
-        // number of indefinite-length strings that have been opened and not
-        // closed yet. RFC 8949, Section 3.2.3 does not permit nesting them,
-        // but this reader has always accepted it, so the open levels are
-        // counted instead of recursed through, which overflowed the stack for
-        // an input of repeated 0x7F bytes (see #5104). Every chunk is appended
-        // to the same result, so no per-level state is needed.
-        std::size_t open = 0;
+        // read chunks iteratively, but reject a second indefinite-length
+        // level as required by RFC 8949, Section 3.2.3
+        bool indefinite = false;
 
         while (true)
         {
@@ -14931,29 +14889,28 @@ class binary_reader
 
             if (current == 0x7F) // UTF-8 string (indefinite length)
             {
-                ++open;
-                get();
-                continue;
-            }
-
-            // a break marker closes the innermost indefinite-length string;
-            // outside of one it is not a string and falls through to the error
-            if (open != 0 && current == 0xFF)
-            {
-                if (--open == 0)
+                if (JSON_HEDLEY_UNLIKELY(indefinite))
                 {
-                    return check_string_utf8(result, context);
+                    return cbor_indefinite_string_error("string", "string");
                 }
+                indefinite = true;
                 get();
                 continue;
             }
 
-            if (JSON_HEDLEY_UNLIKELY(!get_cbor_string_chunk(result)))
+            // a break marker closes the indefinite-length string; outside
+            // of one it falls through to the error below
+            if (indefinite && current == 0xFF)
+            {
+                return check_string_utf8(result, context);
+            }
+
+            if (JSON_HEDLEY_UNLIKELY(!get_cbor_string_chunk(result, indefinite)))
             {
                 return false;
             }
 
-            if (open == 0)
+            if (!indefinite)
             {
                 return check_string_utf8(result, context);
             }
@@ -15045,12 +15002,13 @@ class binary_reader
     read into the same byte array.
 
     @param[out] result  byte array the bytes are appended to
+    @param[in] inside_indefinite  whether the bytes belong to an indefinite-length string
 
     @return whether byte array creation completed
 
     @pre @a current is not EOF
     */
-    bool get_cbor_binary_chunk(binary_t& result)
+    bool get_cbor_binary_chunk(binary_t& result, const bool inside_indefinite)
     {
         switch (current)
         {
@@ -15115,7 +15073,7 @@ class binary_reader
             {
                 auto last_token = get_token_string();
                 return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read,
-                                        exception_message(concat("expected length specification (0x40-0x5B) or indefinite binary array type (0x5F); last byte: 0x", last_token), "binary"), nullptr));
+                                        exception_message(concat("expected length specification (0x40-0x5B)", inside_indefinite ? "" : " or indefinite binary array type (0x5F)", "; last byte: 0x", last_token), "binary"), nullptr));
             }
         }
     }
@@ -15133,9 +15091,9 @@ class binary_reader
     */
     bool get_cbor_binary(binary_t& result)
     {
-        // the open indefinite-length byte arrays are counted rather than
-        // recursed through, for the reason given in @ref get_cbor_string
-        std::size_t open = 0;
+        // read chunks iteratively, but reject a second indefinite-length
+        // level as required by RFC 8949, Section 3.2.3
+        bool indefinite = false;
 
         while (true)
         {
@@ -15146,29 +15104,28 @@ class binary_reader
 
             if (current == 0x5F) // Binary data (indefinite length)
             {
-                ++open;
-                get();
-                continue;
-            }
-
-            // a break marker closes the innermost indefinite-length byte
-            // array; outside of one it falls through to the error below
-            if (open != 0 && current == 0xFF)
-            {
-                if (--open == 0)
+                if (JSON_HEDLEY_UNLIKELY(indefinite))
                 {
-                    return true;
+                    return cbor_indefinite_string_error("binary array", "binary");
                 }
+                indefinite = true;
                 get();
                 continue;
             }
 
-            if (JSON_HEDLEY_UNLIKELY(!get_cbor_binary_chunk(result)))
+            // a break marker closes the indefinite-length string; outside
+            // of one it falls through to the error below
+            if (indefinite && current == 0xFF)
+            {
+                return true;
+            }
+
+            if (JSON_HEDLEY_UNLIKELY(!get_cbor_binary_chunk(result, indefinite)))
             {
                 return false;
             }
 
-            if (open == 0)
+            if (!indefinite)
             {
                 return true;
             }
@@ -21141,6 +21098,7 @@ class json_ref
 
     json_ref(std::initializer_list<json_ref> init)
         : owned_value(init)
+        , braced_list(true)
     {}
 
     template <
@@ -21176,9 +21134,17 @@ class json_ref
         return &** this;
     }
 
+    /// whether the value was written as a braced list, such as {"key", 1},
+    /// rather than given as a value
+    bool is_braced_list() const noexcept
+    {
+        return braced_list;
+    }
+
   private:
     mutable value_type owned_value = nullptr;
     value_type const* value_ref = nullptr;
+    bool braced_list = false;
 };
 
 }  // namespace detail
@@ -27921,6 +27887,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         /// constructor for rvalue binary arrays (internal type)
         json_value(binary_t&& value) : binary(create<binary_t>(std::move(value))) {}
 
+        /// constructors taking ownership of an already created value
+        explicit json_value(string_t* value) noexcept : string(value) {}
+        explicit json_value(object_t* value) noexcept : object(value) {}
+        explicit json_value(array_t* value) noexcept : array(value) {}
+
 private:
         // raw, allocation-free transfer of m_data from src to dst: no
         // set_parents()/assert_invariant() (the former is O(#children) per
@@ -28251,6 +28222,18 @@ public:
 #endif
     }
 
+    /// @brief replace the stored value with an already created one
+    /// The new value must be created before calling this function: if its
+    /// creation throws, the current value is left untouched.
+    void replace_value(value_t t, const json_value& v) noexcept
+    {
+        m_data.m_value.destroy(m_data.m_type);
+        m_data.m_value = v;
+        m_data.m_type = t;
+        set_parents();
+        assert_invariant();
+    }
+
     iterator set_parents(iterator it, std::ptrdiff_t count_set_parents)
     {
 #if JSON_DIAGNOSTICS
@@ -29480,6 +29463,18 @@ public:
                bool type_deduction = true,
                value_t manual_type = value_t::array)
     {
+#if JSON_BRACE_INIT_COPY_SEMANTICS
+        // a single element that is a value rather than a braced list is
+        // copied or moved as is, whatever its content looks like
+        if (type_deduction && init.size() == 1 && !init.begin()->is_braced_list())
+        {
+            *this = init.begin()->moved_or_copied();
+            set_parents();
+            assert_invariant();
+            return;
+        }
+#endif
+
         // check if each element is an array with two elements whose first
         // element is a string
         bool is_an_object = std::all_of(init.begin(), init.end(),
@@ -29510,8 +29505,8 @@ public:
         if (is_an_object)
         {
             // the initializer list is a list of pairs -> create an object
-            m_data.m_type = value_t::object;
             m_data.m_value = value_t::object;
+            m_data.m_type = value_t::object;
 
             for (auto& element_ref : init)
             {
@@ -29533,8 +29528,8 @@ public:
             }
 #endif
             // the initializer list describes an array -> create an array
-            m_data.m_type = value_t::array;
             m_data.m_value.array = create<array_t>(init.begin(), init.end());
+            m_data.m_type = value_t::array;
         }
 
         set_parents();
@@ -29547,8 +29542,8 @@ public:
     static basic_json binary(const typename binary_t::container_type& init)
     {
         auto res = basic_json();
-        res.m_data.m_type = value_t::binary;
         res.m_data.m_value = init;
+        res.m_data.m_type = value_t::binary;
         return res;
     }
 
@@ -29558,8 +29553,8 @@ public:
     static basic_json binary(const typename binary_t::container_type& init, typename binary_t::subtype_type subtype)
     {
         auto res = basic_json();
-        res.m_data.m_type = value_t::binary;
         res.m_data.m_value = binary_t(init, subtype);
+        res.m_data.m_type = value_t::binary;
         return res;
     }
 
@@ -29569,8 +29564,8 @@ public:
     static basic_json binary(typename binary_t::container_type&& init)
     {
         auto res = basic_json();
-        res.m_data.m_type = value_t::binary;
         res.m_data.m_value = std::move(init);
+        res.m_data.m_type = value_t::binary;
         return res;
     }
 
@@ -29580,8 +29575,8 @@ public:
     static basic_json binary(typename binary_t::container_type&& init, typename binary_t::subtype_type subtype)
     {
         auto res = basic_json();
-        res.m_data.m_type = value_t::binary;
         res.m_data.m_value = binary_t(std::move(init), subtype);
+        res.m_data.m_type = value_t::binary;
         return res;
     }
 

tests/CMakeLists.txt

@@ -135,12 +135,14 @@ json_test_set_test_options(test-disabled_exceptions
         #$<$<CXX_COMPILER_ID:MSVC>:/EH>
 )
 
-# raise timeout of expensive Unicode test
-json_test_set_test_options(test-unicode4 TEST_PROPERTIES TIMEOUT 3000)
-
 # only the #972 regression test needs thirdparty/fifo_map on its include path
 json_test_set_test_options(test-regression1 LINK_LIBRARIES fifo_map_include)
 
+# GCC's false -Warray-bounds error with JSON_DIAGNOSTICS only shows up when optimizing (#5742)
+json_test_set_test_options(test-diagnostics-optimized
+    COMPILE_OPTIONS $<$<CXX_COMPILER_ID:GNU>:-O3 -Werror=array-bounds>
+)
+
 #############################################################################
 # add unit tests
 #############################################################################

tests/fuzzing.md

@@ -3,6 +3,14 @@
 Each parser of the library (JSON, BJData, BON8, BSON, CBOR, MessagePack, and UBJSON) can be fuzz tested. Currently,
 [libFuzzer](https://llvm.org/docs/LibFuzzer.html) and [afl++](https://github.com/AFLplusplus/AFLplusplus) are supported.
 
+## What the fuzzers check
+
+Each fuzzer driver (`tests/src/fuzzer-parse_*.cpp`) parses its input twice: once with `allow_exceptions = false` and
+once with exceptions. Both calls must agree. Where parsing with exceptions fails, the call without exceptions must
+return a discarded value (or throw the same kind of non-parse error), and it must never throw a `parse_error`. Where
+parsing succeeds, both calls must return the same value. The drivers then serialize the value, parse the result back,
+and check that nothing was lost. The drivers check all of this with `assert`, so they refuse to build with `NDEBUG`.
+
 ## Corpus creation
 
 For most effective fuzzing, a [corpus](https://llvm.org/docs/LibFuzzer.html#corpus) should be provided. A corpus is a
@@ -54,6 +62,9 @@ Then pass the corpus directory as command-line argument (assuming it is located
 The fuzzer should be able to run indefinitely without crashing. In case of a crash, the tested input is dumped into
 a file starting with `crash-`.
 
+To also detect memory leaks, build with AddressSanitizer (`FUZZER_ENGINE="-fsanitize=fuzzer,address"`): libFuzzer then
+runs LeakSanitizer by default (`-detect_leaks=1`). LeakSanitizer is not available with Apple Clang on macOS.
+
 ## afl++
 
 To use afl++, you need to pass `-fsanitize=fuzzer` as `FUZZER_ENGINE`. It will be replaced by a `libAFLDriver.a` to
@@ -76,7 +87,9 @@ directory `out`.
 
 The library is further fuzz-tested 24/7 by Google's [OSS-Fuzz project](https://github.com/google/oss-fuzz). It uses
 the same `fuzzers` target as above and also relies on the `FUZZER_ENGINE` variable. See the used
-[build script](https://github.com/google/oss-fuzz/blob/master/projects/json/build.sh) for more information.
+[build script](https://github.com/google/oss-fuzz/blob/master/projects/json/build.sh) for more information. Its default
+`address` sanitizer includes LeakSanitizer, so OSS-Fuzz and the CIFuzz workflow (`.github/workflows/cifuzz.yml`) report
+memory leaks, too.
 
 In case the build at OSS-Fuzz fails, an issue will be created automatically.
 

tests/src/fuzzer-parse_bjdata.cpp

@@ -10,7 +10,9 @@
 This file implements a parser test suitable for fuzz testing. Given a byte
 array data, it performs the following steps:
 
+- j0 = from_bjdata(data, allow_exceptions = false)
 - j1 = from_bjdata(data)
+- assert(j0 is discarded if parsing j1 fails, and j0 == j1 otherwise)
 - vec2 = to_bjdata(j1, use_size = false, use_type = false)
 - vec3 = to_bjdata(j1, use_size = true, use_type = false)
 - vec4 = to_bjdata(j1, use_size = true, use_type = true)
@@ -59,6 +61,13 @@ drivers.
 
 using json = nlohmann::json;
 
+// compares dumps rather than values, because NaN != NaN; keep writes strings
+// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
+static bool same_value(const json& lhs, const json& rhs)
+{
+    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
+}
+
 // value-stable comparison for the round-trip checks below; see the note
 // above on why this compares dump()s rather than the json values directly
 static bool is_value_stable(const json& lhs, const json& rhs)
@@ -69,11 +78,37 @@ static bool is_value_stable(const json& lhs, const json& rhs)
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
+    std::vector<uint8_t> const vec1(data, data + size);
+
+    // step 0: parse input without exceptions; a parse error must then be
+    // reported as a discarded value, never thrown
+    json j_noexcept;
+    bool noexcept_threw = false;
+    try
+    {
+        j_noexcept = json::from_bjdata(vec1, true, false);
+    }
+    catch (const json::parse_error&)
+    {
+        assert(false);
+    }
+    catch (const json::exception&)
+    {
+        // type and out-of-range errors are not parse errors and still throw
+        noexcept_threw = true;
+    }
+    // whether step 1 succeeded; if not, the catch blocks below check that
+    // step 0 failed, too
+    bool parsed = false;
+
     try
     {
         // step 1: parse input
-        std::vector<uint8_t> const vec1(data, data + size);
         json const j1 = json::from_bjdata(vec1);
+        parsed = true;
+
+        // without exceptions, the same input must give the same value
+        assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
         try
         {
@@ -107,14 +142,17 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     catch (const json::parse_error&)
     {
         // parse errors are ok, because input may be random bytes
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::type_error&)
     {
         // type errors can occur during parsing, too
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::out_of_range&)
     {
         // out of range errors may happen if provided sizes are excessive
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_bon8.cpp

@@ -10,7 +10,9 @@
 This file implements a parser test suitable for fuzz testing. Given a byte
 array data, it performs the following steps:
 
+- j0 = from_bon8(data, allow_exceptions = false)
 - j1 = from_bon8(data)
+- assert(j0 is discarded if parsing j1 fails, and j0 == j1 otherwise)
 - vec = to_bon8(j1)
 - j2 = from_bon8(vec)
 - assert(to_bon8(j2) == vec)
@@ -34,6 +36,13 @@ drivers.
 
 using json = nlohmann::json;
 
+// compares dumps rather than values, because NaN != NaN; keep writes strings
+// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
+static bool same_value(const json& lhs, const json& rhs)
+{
+    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
+}
+
 namespace
 {
 // the serialization of the value read from @a input, or the error message
@@ -61,11 +70,37 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
         assert(read_bon8(std::vector<uint8_t>(data, data + size)) == read_bon8(stream));
     }
 
+    std::vector<uint8_t> const vec1(data, data + size);
+
+    // step 0: parse input without exceptions; a parse error must then be
+    // reported as a discarded value, never thrown
+    json j_noexcept;
+    bool noexcept_threw = false;
+    try
+    {
+        j_noexcept = json::from_bon8(vec1, true, false);
+    }
+    catch (const json::parse_error&)
+    {
+        assert(false);
+    }
+    catch (const json::exception&)
+    {
+        // type and out-of-range errors are not parse errors and still throw
+        noexcept_threw = true;
+    }
+    // whether step 1 succeeded; if not, the catch blocks below check that
+    // step 0 failed, too
+    bool parsed = false;
+
     try
     {
         // step 1: parse input
-        std::vector<uint8_t> const vec1(data, data + size);
         json const j1 = json::from_bon8(vec1);
+        parsed = true;
+
+        // without exceptions, the same input must give the same value
+        assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
         try
         {
@@ -87,14 +122,17 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     catch (const json::parse_error&)
     {
         // parse errors are ok, because input may be random bytes
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::type_error&)
     {
         // type errors can occur during parsing, too
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::out_of_range&)
     {
         // out of range errors may happen if provided sizes are excessive
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_bson.cpp

@@ -10,7 +10,9 @@
 This file implements a parser test suitable for fuzz testing. Given a byte
 array data, it performs the following steps:
 
+- j0 = from_bson(data, allow_exceptions = false)
 - j1 = from_bson(data)
+- assert(j0 is discarded if parsing j1 fails, and j0 == j1 otherwise)
 - vec = to_bson(j1)
 - j2 = from_bson(vec)
 - assert(to_bson(j2) == vec)
@@ -29,14 +31,47 @@ drivers.
 
 using json = nlohmann::json;
 
+// compares dumps rather than values, because NaN != NaN; keep writes strings
+// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
+static bool same_value(const json& lhs, const json& rhs)
+{
+    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
+}
+
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
+    std::vector<uint8_t> const vec1(data, data + size);
+
+    // step 0: parse input without exceptions; a parse error must then be
+    // reported as a discarded value, never thrown
+    json j_noexcept;
+    bool noexcept_threw = false;
+    try
+    {
+        j_noexcept = json::from_bson(vec1, true, false);
+    }
+    catch (const json::parse_error&)
+    {
+        assert(false);
+    }
+    catch (const json::exception&)
+    {
+        // type and out-of-range errors are not parse errors and still throw
+        noexcept_threw = true;
+    }
+    // whether step 1 succeeded; if not, the catch blocks below check that
+    // step 0 failed, too
+    bool parsed = false;
+
     try
     {
         // step 1: parse input
-        std::vector<uint8_t> const vec1(data, data + size);
         json const j1 = json::from_bson(vec1);
+        parsed = true;
+
+        // without exceptions, the same input must give the same value
+        assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
         try
         {
@@ -58,14 +93,17 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     catch (const json::parse_error&)
     {
         // parse errors are ok, because input may be random bytes
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::type_error&)
     {
         // type errors can occur during parsing, too
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::out_of_range&)
     {
         // out of range errors can occur during parsing, too
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_cbor.cpp

@@ -10,7 +10,9 @@
 This file implements a parser test suitable for fuzz testing. Given a byte
 array data, it performs the following steps:
 
+- j0 = from_cbor(data, allow_exceptions = false)
 - j1 = from_cbor(data)
+- assert(j0 is discarded if parsing j1 fails, and j0 == j1 otherwise)
 - vec = to_cbor(j1)
 - j2 = from_cbor(vec)
 - assert(to_cbor(j2) == vec)
@@ -29,14 +31,47 @@ drivers.
 
 using json = nlohmann::json;
 
+// compares dumps rather than values, because NaN != NaN; keep writes strings
+// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
+static bool same_value(const json& lhs, const json& rhs)
+{
+    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
+}
+
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
+    std::vector<uint8_t> const vec1(data, data + size);
+
+    // step 0: parse input without exceptions; a parse error must then be
+    // reported as a discarded value, never thrown
+    json j_noexcept;
+    bool noexcept_threw = false;
+    try
+    {
+        j_noexcept = json::from_cbor(vec1, true, false);
+    }
+    catch (const json::parse_error&)
+    {
+        assert(false);
+    }
+    catch (const json::exception&)
+    {
+        // type and out-of-range errors are not parse errors and still throw
+        noexcept_threw = true;
+    }
+    // whether step 1 succeeded; if not, the catch blocks below check that
+    // step 0 failed, too
+    bool parsed = false;
+
     try
     {
         // step 1: parse input
-        std::vector<uint8_t> const vec1(data, data + size);
         json const j1 = json::from_cbor(vec1);
+        parsed = true;
+
+        // without exceptions, the same input must give the same value
+        assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
         try
         {
@@ -58,14 +93,17 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     catch (const json::parse_error&)
     {
         // parse errors are ok, because input may be random bytes
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::type_error&)
     {
         // type errors can occur during parsing, too
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::out_of_range&)
     {
         // out of range errors can occur during parsing, too
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_json.cpp

@@ -10,7 +10,9 @@
 This file implements a parser test suitable for fuzz testing. Given a byte
 array data, it performs the following steps:
 
+- j0 = parse(data, allow_exceptions = false)
 - j1 = parse(data)
+- assert(j0 is discarded if parsing j1 fails, and j0 == j1 otherwise)
 - s1 = serialize(j1)
 - j2 = parse(s1)
 - s2 = serialize(j2)
@@ -30,13 +32,45 @@ drivers.
 
 using json = nlohmann::json;
 
+// compares dumps rather than values, because NaN != NaN; keep writes strings
+// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
+static bool same_value(const json& lhs, const json& rhs)
+{
+    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
+}
+
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
+    // step 0: parse input without exceptions; a parse error must then be
+    // reported as a discarded value, never thrown
+    json j_noexcept;
+    bool noexcept_threw = false;
+    try
+    {
+        j_noexcept = json::parse(data, data + size, nullptr, false);
+    }
+    catch (const json::parse_error&)
+    {
+        assert(false);
+    }
+    catch (const json::exception&)
+    {
+        // type and out-of-range errors are not parse errors and still throw
+        noexcept_threw = true;
+    }
+    // whether step 1 succeeded; if not, the catch blocks below check that
+    // step 0 failed, too
+    bool parsed = false;
+
     try
     {
         // step 1: parse input
         json const j1 = json::parse(data, data + size);
+        parsed = true;
+
+        // without exceptions, the same input must give the same value
+        assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
         try
         {
@@ -63,10 +97,12 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     catch (const json::parse_error&)
     {
         // parse errors are ok, because input may be random bytes
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::out_of_range&)
     {
         // out of range errors may happen if provided sizes are excessive
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_msgpack.cpp

@@ -10,7 +10,9 @@
 This file implements a parser test suitable for fuzz testing. Given a byte
 array data, it performs the following steps:
 
+- j0 = from_msgpack(data, allow_exceptions = false)
 - j1 = from_msgpack(data)
+- assert(j0 is discarded if parsing j1 fails, and j0 == j1 otherwise)
 - vec = to_msgpack(j1)
 - j2 = from_msgpack(vec)
 - assert(to_msgpack(j2) == vec)
@@ -29,14 +31,47 @@ drivers.
 
 using json = nlohmann::json;
 
+// compares dumps rather than values, because NaN != NaN; keep writes strings
+// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
+static bool same_value(const json& lhs, const json& rhs)
+{
+    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
+}
+
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
+    std::vector<uint8_t> const vec1(data, data + size);
+
+    // step 0: parse input without exceptions; a parse error must then be
+    // reported as a discarded value, never thrown
+    json j_noexcept;
+    bool noexcept_threw = false;
+    try
+    {
+        j_noexcept = json::from_msgpack(vec1, true, false);
+    }
+    catch (const json::parse_error&)
+    {
+        assert(false);
+    }
+    catch (const json::exception&)
+    {
+        // type and out-of-range errors are not parse errors and still throw
+        noexcept_threw = true;
+    }
+    // whether step 1 succeeded; if not, the catch blocks below check that
+    // step 0 failed, too
+    bool parsed = false;
+
     try
     {
         // step 1: parse input
-        std::vector<uint8_t> const vec1(data, data + size);
         json const j1 = json::from_msgpack(vec1);
+        parsed = true;
+
+        // without exceptions, the same input must give the same value
+        assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
         try
         {
@@ -58,14 +93,17 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     catch (const json::parse_error&)
     {
         // parse errors are ok, because input may be random bytes
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::type_error&)
     {
         // type errors can occur during parsing, too
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::out_of_range&)
     {
         // out of range errors may happen if provided sizes are excessive
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_ubjson.cpp

@@ -10,7 +10,9 @@
 This file implements a parser test suitable for fuzz testing. Given a byte
 array data, it performs the following steps:
 
+- j0 = from_ubjson(data, allow_exceptions = false)
 - j1 = from_ubjson(data)
+- assert(j0 is discarded if parsing j1 fails, and j0 == j1 otherwise)
 - vec2 = to_ubjson(j1, use_size = false, use_type = false)
 - vec3 = to_ubjson(j1, use_size = true, use_type = false)
 - vec4 = to_ubjson(j1, use_size = true, use_type = true)
@@ -38,14 +40,47 @@ drivers.
 
 using json = nlohmann::json;
 
+// compares dumps rather than values, because NaN != NaN; keep writes strings
+// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
+static bool same_value(const json& lhs, const json& rhs)
+{
+    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
+}
+
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
+    std::vector<uint8_t> const vec1(data, data + size);
+
+    // step 0: parse input without exceptions; a parse error must then be
+    // reported as a discarded value, never thrown
+    json j_noexcept;
+    bool noexcept_threw = false;
+    try
+    {
+        j_noexcept = json::from_ubjson(vec1, true, false);
+    }
+    catch (const json::parse_error&)
+    {
+        assert(false);
+    }
+    catch (const json::exception&)
+    {
+        // type and out-of-range errors are not parse errors and still throw
+        noexcept_threw = true;
+    }
+    // whether step 1 succeeded; if not, the catch blocks below check that
+    // step 0 failed, too
+    bool parsed = false;
+
     try
     {
         // step 1: parse input
-        std::vector<uint8_t> const vec1(data, data + size);
         json const j1 = json::from_ubjson(vec1);
+        parsed = true;
+
+        // without exceptions, the same input must give the same value
+        assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
         try
         {
@@ -77,14 +112,17 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     catch (const json::parse_error&)
     {
         // parse errors are ok, because input may be random bytes
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::type_error&)
     {
         // type errors can occur during parsing, too
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
     catch (const json::out_of_range&)
     {
         // out of range errors may happen if provided sizes are excessive
+        assert(parsed || noexcept_threw || j_noexcept.is_discarded());
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/test_utils.hpp

@@ -8,6 +8,7 @@
 
 #pragma once
 
+#include <array> // array
 #include <cstdint> // uint8_t
 #include <cstddef> // size_t
 #include <fstream> // ifstream, ios
@@ -43,6 +44,33 @@ T next_integer_sample(T i, T last, T stride)
     return n < last ? n : last;
 }
 
+// UTF-8 continuation bytes in [lo, hi] that stand in for all of them in the
+// ill-formed UTF-8 tests. Both the lexer's range checks and the serializer's
+// decoder (detail::decode) only distinguish the classes 0x80..0x8F, 0x90..0x9F,
+// and 0xA0..0xBF, so the first and last byte of each class within [lo, hi]
+// exercise every behavior while a test sweeps another byte position through
+// all 256 values (#5418). Define JSON_TEST_UTF8_EXHAUSTIVE to get every byte.
+inline std::vector<int> utf8_continuation_bytes(int lo, int hi)
+{
+    std::vector<int> result;
+#ifdef JSON_TEST_UTF8_EXHAUSTIVE
+    for (int byte = lo; byte <= hi; ++byte)
+    {
+        result.push_back(byte);
+    }
+#else
+    static const std::array<int, 6> class_ends = {{0x80, 0x8F, 0x90, 0x9F, 0xA0, 0xBF}};
+    for (const int byte : class_ends)
+    {
+        if (lo <= byte && byte <= hi)
+        {
+            result.push_back(byte);
+        }
+    }
+#endif
+    return result;
+}
+
 inline std::vector<std::uint8_t> read_binary_file(const std::string& filename)
 {
     std::ifstream file(filename, std::ios::binary);

tests/src/unit-allocator.cpp

@@ -12,6 +12,11 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
+#include <valarray>
+#if JSON_HAS_RANGES
+    #include <ranges>
+#endif
+
 namespace
 {
 // special test case to check if memory is leaked if constructor throws
@@ -671,3 +676,173 @@ TEST_CASE("destructor performs no allocation, only deallocation")
         CHECK(counting_allocator_deallocations > deallocations_before);
     }
 }
+
+// the no-exceptions CI job skips every CHECK_THROWS_AS, which would leave
+// next_construct_fails set for the next allocation outside a check
+#if !defined(JSON_NOEXCEPTION)
+TEST_CASE("a failed allocation leaves the value unchanged")
+{
+    // create JSON type using the throwing allocator
+    using my_json = nlohmann::basic_json<std::map,
+          std::vector,
+          std::string,
+          bool,
+          std::int64_t,
+          std::uint64_t,
+          double,
+          my_allocator>;
+
+    // Each of these creates a string, array, object, or binary value. The
+    // value must be created before the type is changed: otherwise, a failed
+    // creation left a value of the new type without anything behind it (an
+    // assertion in its destructor, a null pointer everywhere else) or, when
+    // an old value was destroyed first, with a pointer to that destroyed one.
+
+    SECTION("creating a binary value")
+    {
+        const std::vector<std::uint8_t> bytes = {1, 2, 3};
+        my_json _;
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(_ = my_json::binary(bytes), std::bad_alloc&);
+        next_construct_fails = true;
+        CHECK_THROWS_AS(_ = my_json::binary(bytes, 42), std::bad_alloc&);
+        next_construct_fails = true;
+        CHECK_THROWS_AS(_ = my_json::binary(std::vector<std::uint8_t>(bytes)), std::bad_alloc&);
+        next_construct_fails = true;
+        CHECK_THROWS_AS(_ = my_json::binary(std::vector<std::uint8_t>(bytes), 42), std::bad_alloc&);
+        next_construct_fails = false;
+    }
+
+    SECTION("turning a null value into an array or object")
+    {
+        my_json j;
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(j[0], std::bad_alloc&);
+        CHECK(j.is_null());
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(j["key"], std::bad_alloc&);
+        CHECK(j.is_null());
+
+#ifdef JSON_HAS_CPP_17
+        next_construct_fails = true;
+        CHECK_THROWS_AS(j[std::string_view("key")], std::bad_alloc&);
+        CHECK(j.is_null());
+#endif
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(j.push_back(my_json(1)), std::bad_alloc&);
+        CHECK(j.is_null());
+
+        const my_json one = 1;
+        next_construct_fails = true;
+        CHECK_THROWS_AS(j.push_back(one), std::bad_alloc&);
+        CHECK(j.is_null());
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(j.push_back(my_json::object_t::value_type("key", 1)), std::bad_alloc&);
+        CHECK(j.is_null());
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(j.emplace_back(1), std::bad_alloc&);
+        CHECK(j.is_null());
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(j.emplace("key", 1), std::bad_alloc&);
+        CHECK(j.is_null());
+
+        const my_json object = {{"key", 1}};
+        next_construct_fails = true;
+        CHECK_THROWS_AS(j.update(object), std::bad_alloc&);
+        CHECK(j.is_null());
+
+        next_construct_fails = false;
+    }
+
+    // With iterator debugging, VS 2015's containers construct a proxy with the
+    // allocator in constructors that cannot report its failure, so a failing
+    // allocator crashes this section there (SIGSEGV with VS 2015 Debug x86).
+#if !(defined(_MSC_VER) && _MSC_VER < 1910 && defined(_ITERATOR_DEBUG_LEVEL) && _ITERATOR_DEBUG_LEVEL > 0)
+    SECTION("converting into an existing value")
+    {
+        // to_json replaces the value it is given; the old one must survive a
+        // failed creation of the new one
+        my_json j = "old";
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, std::string("new")), std::bad_alloc&);
+        CHECK(j == "old");
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, std::vector<int> {1, 2}), std::bad_alloc&);
+        CHECK(j == "old");
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, std::vector<bool> {true, false}), std::bad_alloc&);
+        CHECK(j == "old");
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, std::map<std::string, int> {{"a", 1}}), std::bad_alloc&);
+        CHECK(j == "old");
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, my_json::binary_t({1, 2})), std::bad_alloc&);
+        CHECK(j == "old");
+
+        // the overloads for lvalues of the value types, for the value types
+        // themselves, and for the remaining compatible types
+        const std::string string = "new";
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, string), std::bad_alloc&);
+        CHECK(j == "old");
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, "new"), std::bad_alloc&);
+        CHECK(j == "old");
+
+        // to_json only moves a binary value that it converted from another
+        // container type, which my_json's std::vector<std::uint8_t> is not
+        using binary_constructor = nlohmann::detail::external_constructor<nlohmann::detail::value_t::binary>;
+        next_construct_fails = true;
+        CHECK_THROWS_AS(binary_constructor::construct(j, my_json::binary_t({1, 2})), std::bad_alloc&);
+        CHECK(j == "old");
+
+        my_json::array_t array = {1, 2};
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, array), std::bad_alloc&);
+        CHECK(j == "old");
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, std::move(array)), std::bad_alloc&);
+        CHECK(j == "old");
+
+        my_json::object_t object = {{"a", 1}};
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, object), std::bad_alloc&);
+        CHECK(j == "old");
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, std::move(object)), std::bad_alloc&);
+        CHECK(j == "old");
+
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, std::valarray<int> {1, 2}), std::bad_alloc&);
+        CHECK(j == "old");
+
+#if JSON_HAS_RANGES && !defined(__MINGW32__)
+        const std::vector<int> numbers = {1, 2};
+        next_construct_fails = true;
+        CHECK_THROWS_AS(nlohmann::to_json(j, numbers | std::views::filter([](int /*unused*/)
+        {
+            return true;
+        })), std::bad_alloc&);
+        CHECK(j == "old");
+#endif
+
+        next_construct_fails = false;
+        nlohmann::to_json(j, std::vector<int> {1, 2});
+        CHECK(j == my_json({1, 2}));
+    }
+#endif
+}
+#endif

tests/src/unit-binary_formats.cpp

@@ -19,7 +19,7 @@ using nlohmann::json;
 #include <vector>
 #include "make_test_data_available.hpp"
 
-TEST_CASE("Binary Formats" * doctest::skip())
+TEST_CASE("Binary Formats")
 {
     SECTION("canada.json")
     {
@@ -147,48 +147,6 @@ TEST_CASE("Binary Formats" * doctest::skip())
         CHECK((100.0 * double(ubjson_3_size) / double(json_size)) == Approx(84.963));
     }
 
-    SECTION("jeopardy.json")
-    {
-        const auto* filename = TEST_DATA_DIRECTORY "/jeopardy/jeopardy.json";
-        json j = json::parse(std::ifstream(filename));
-
-        const auto json_size = j.dump().size();
-        const auto bjdata_1_size = json::to_bjdata(j).size();
-        const auto bjdata_2_size = json::to_bjdata(j, true).size();
-        const auto bjdata_3_size = json::to_bjdata(j, true, true).size();
-        const auto bon8_size = json::to_bon8(j).size();
-        const auto bson_size = json::to_bson({{"", j}}).size(); // wrap array in object for BSON
-        const auto cbor_size = json::to_cbor(j).size();
-        const auto msgpack_size = json::to_msgpack(j).size();
-        const auto ubjson_1_size = json::to_ubjson(j).size();
-        const auto ubjson_2_size = json::to_ubjson(j, true).size();
-        const auto ubjson_3_size = json::to_ubjson(j, true, true).size();
-
-        CHECK(json_size == 52508728);
-        CHECK(bjdata_1_size == 50710965);
-        CHECK(bjdata_2_size == 51144830);
-        CHECK(bjdata_3_size == 51144830);
-        CHECK(bon8_size == 45942080);
-        CHECK(bson_size == 56008520);
-        CHECK(cbor_size == 46187320);
-        CHECK(msgpack_size == 46158575);
-        CHECK(ubjson_1_size == 50710965);
-        CHECK(ubjson_2_size == 51144830);
-        CHECK(ubjson_3_size == 49861422);
-
-        CHECK((100.0 * double(json_size) / double(json_size)) == Approx(100.0));
-        CHECK((100.0 * double(bjdata_1_size) / double(json_size)) == Approx(96.576));
-        CHECK((100.0 * double(bjdata_2_size) / double(json_size)) == Approx(97.402));
-        CHECK((100.0 * double(bjdata_3_size) / double(json_size)) == Approx(97.402));
-        CHECK((100.0 * double(bon8_size) / double(json_size)) == Approx(87.494));
-        CHECK((100.0 * double(bson_size) / double(json_size)) == Approx(106.665));
-        CHECK((100.0 * double(cbor_size) / double(json_size)) == Approx(87.961));
-        CHECK((100.0 * double(msgpack_size) / double(json_size)) == Approx(87.906));
-        CHECK((100.0 * double(ubjson_1_size) / double(json_size)) == Approx(96.576));
-        CHECK((100.0 * double(ubjson_2_size) / double(json_size)) == Approx(97.402));
-        CHECK((100.0 * double(ubjson_3_size) / double(json_size)) == Approx(94.958));
-    }
-
     SECTION("sample.json")
     {
         const auto* filename = TEST_DATA_DIRECTORY "/json_testsuite/sample.json";
@@ -230,6 +188,50 @@ TEST_CASE("Binary Formats" * doctest::skip())
     }
 }
 
+// jeopardy.json is 52 MB and produces ~500 MB of serialization output, so it
+// is kept apart from the cheap corpus files above (#5418)
+TEST_CASE("Binary Formats (jeopardy.json)" * doctest::skip())
+{
+    const auto* filename = TEST_DATA_DIRECTORY "/jeopardy/jeopardy.json";
+    json j = json::parse(std::ifstream(filename));
+
+    const auto json_size = j.dump().size();
+    const auto bjdata_1_size = json::to_bjdata(j).size();
+    const auto bjdata_2_size = json::to_bjdata(j, true).size();
+    const auto bjdata_3_size = json::to_bjdata(j, true, true).size();
+    const auto bon8_size = json::to_bon8(j).size();
+    const auto bson_size = json::to_bson({{"", j}}).size(); // wrap array in object for BSON
+    const auto cbor_size = json::to_cbor(j).size();
+    const auto msgpack_size = json::to_msgpack(j).size();
+    const auto ubjson_1_size = json::to_ubjson(j).size();
+    const auto ubjson_2_size = json::to_ubjson(j, true).size();
+    const auto ubjson_3_size = json::to_ubjson(j, true, true).size();
+
+    CHECK(json_size == 52508728);
+    CHECK(bjdata_1_size == 50710965);
+    CHECK(bjdata_2_size == 51144830);
+    CHECK(bjdata_3_size == 51144830);
+    CHECK(bon8_size == 45942080);
+    CHECK(bson_size == 56008520);
+    CHECK(cbor_size == 46187320);
+    CHECK(msgpack_size == 46158575);
+    CHECK(ubjson_1_size == 50710965);
+    CHECK(ubjson_2_size == 51144830);
+    CHECK(ubjson_3_size == 49861422);
+
+    CHECK((100.0 * double(json_size) / double(json_size)) == Approx(100.0));
+    CHECK((100.0 * double(bjdata_1_size) / double(json_size)) == Approx(96.576));
+    CHECK((100.0 * double(bjdata_2_size) / double(json_size)) == Approx(97.402));
+    CHECK((100.0 * double(bjdata_3_size) / double(json_size)) == Approx(97.402));
+    CHECK((100.0 * double(bon8_size) / double(json_size)) == Approx(87.494));
+    CHECK((100.0 * double(bson_size) / double(json_size)) == Approx(106.665));
+    CHECK((100.0 * double(cbor_size) / double(json_size)) == Approx(87.961));
+    CHECK((100.0 * double(msgpack_size) / double(json_size)) == Approx(87.906));
+    CHECK((100.0 * double(ubjson_1_size) / double(json_size)) == Approx(96.576));
+    CHECK((100.0 * double(ubjson_2_size) / double(json_size)) == Approx(97.402));
+    CHECK((100.0 * double(ubjson_3_size) / double(json_size)) == Approx(94.958));
+}
+
 namespace
 {
 // the binary formats as function pointers for "Binary formats with narrow number types";

tests/src/unit-bjdata.cpp

@@ -4603,3 +4603,49 @@ TEST_CASE("issue #5648 - from_bjdata(ptr, len) must read len bytes, not treat pt
     CHECK(json::from_bjdata(packed.data(), packed.size(), false) == j);
 #endif
 }
+
+TEST_CASE("BJData large strings and binaries (chunked reader)")
+{
+    // Strings share get_ubjson_string() -> get_string() -> get_bytes() with
+    // plain UBJSON. Binary values are different: only a Draft 3 optimized
+    // array (type marker 'B') is read back as a binary value, through
+    // get_binary() -> get_bytes() (see parse_ubjson_internal()'s "If BJData
+    // type marker is 'B'" branch); Draft 2 (the default) writes a binary
+    // value as a plain array of uint8_t numbers instead (see the "round trip
+    // of a binary value is value-stable, not byte-stable" test above), which
+    // never reaches get_bytes(). Both reads happen in bounded chunks
+    // (binary_reader.hpp, chunk_size == 4096); check lengths around and
+    // beyond that size, for both vector (iterator) and pointer inputs.
+    for (const std::size_t len :
+            {
+                std::size_t{0}, std::size_t{1}, std::size_t{4095}, std::size_t{4096},
+                std::size_t{4097}, std::size_t{8192}, std::size_t{100000}
+            })
+    {
+        CAPTURE(len)
+
+        // string
+        const json j_string = std::string(len, 'x');
+        const std::vector<std::uint8_t> v_string = json::to_bjdata(j_string);
+        CHECK(json::from_bjdata(v_string) == j_string);
+        // pointer input exercises the std::memcpy fast path
+        CHECK(json::from_bjdata(reinterpret_cast<const char*>(v_string.data()),
+                                reinterpret_cast<const char*>(v_string.data()) + v_string.size()) == j_string);
+
+        // binary, forced into the Draft 3 optimized ('B' marker) encoding
+        const json j_binary = json::binary(std::vector<std::uint8_t>(len, 0xCD));
+        const std::vector<std::uint8_t> v_binary = json::to_bjdata(j_binary, true, true, json::bjdata_version_t::draft3);
+        CHECK(json::from_bjdata(v_binary) == j_binary);
+        CHECK(json::from_bjdata(reinterpret_cast<const char*>(v_binary.data()),
+                                reinterpret_cast<const char*>(v_binary.data()) + v_binary.size()) == j_binary);
+
+        // a truncated payload must still be reported as an error
+        if (len > 16)
+        {
+            std::vector<std::uint8_t> truncated = v_string;
+            truncated.resize(truncated.size() - 8);
+            json _;
+            CHECK_THROWS_AS(_ = json::from_bjdata(truncated), json::parse_error);
+        }
+    }
+}

tests/src/unit-brace-init-copy-semantics.cpp

@@ -72,6 +72,28 @@ TEST_CASE("JSON_BRACE_INIT_COPY_SEMANTICS")
         CHECK(j7 == json::array({1, 2}));
     }
 
+    SECTION("single-element brace initialization copies a pair-shaped array value (#5662)")
+    {
+        // a JSON value that happens to be a 2-element array whose first
+        // element is a string must still be copied, not turned into an
+        // object; only a braced list written in the source, such as the
+        // inner {"key", "value"} of {{"key", "value"}}, describes an object
+        json const pair_shaped = json::array({"key", 42});
+
+        json const j1{pair_shaped};
+        CHECK(j1.is_array());
+        CHECK(j1 == pair_shaped);
+
+        json const j2 = {pair_shaped};
+        CHECK(j2.is_array());
+        CHECK(j2 == pair_shaped);
+
+        // the same holds for an rvalue of the same shape
+        json const j3{json::array({"key", 42})};
+        CHECK(j3.is_array());
+        CHECK(j3 == pair_shaped);
+    }
+
     SECTION("what the macro does not change")
     {
         // lists with more than one element are unaffected

tests/src/unit-bson.cpp

@@ -1993,3 +1993,47 @@ TEST_CASE("Invalid document size handling")
         CHECK(json::from_bson(v, true, false).is_discarded());
     }
 }
+
+TEST_CASE("BSON large strings and binaries (chunked reader)")
+{
+    // get_bson_string()/get_bson_binary() both read through get_string()/
+    // get_binary(), which read in bounded chunks (binary_reader.hpp,
+    // chunk_size == 4096); make sure roundtripping is correct for lengths
+    // around and beyond that chunk size, for both vector (iterator) and
+    // pointer inputs. BSON only accepts an object at the top level, so the
+    // string/binary value is wrapped in one.
+    for (const std::size_t len :
+            {
+                std::size_t{0}, std::size_t{1}, std::size_t{4095}, std::size_t{4096},
+                std::size_t{4097}, std::size_t{8192}, std::size_t{100000}
+            })
+    {
+        CAPTURE(len)
+
+        // string
+        const json j_string = {{"k", std::string(len, 'x')}};
+        const std::vector<std::uint8_t> v_string = json::to_bson(j_string);
+        CHECK(json::from_bson(v_string) == j_string);
+        // pointer input exercises the std::memcpy fast path
+        CHECK(json::from_bson(reinterpret_cast<const char*>(v_string.data()),
+                              reinterpret_cast<const char*>(v_string.data()) + v_string.size()) == j_string);
+
+        // binary (BSON binary values always carry a subtype, so give one
+        // explicitly; otherwise from_bson() would round-trip to subtype 0
+        // rather than back to the original "no subtype" value)
+        const json j_binary = {{"k", json::binary(std::vector<std::uint8_t>(len, 0xCD), std::uint8_t{0})}};
+        const std::vector<std::uint8_t> v_binary = json::to_bson(j_binary);
+        CHECK(json::from_bson(v_binary) == j_binary);
+        CHECK(json::from_bson(reinterpret_cast<const char*>(v_binary.data()),
+                              reinterpret_cast<const char*>(v_binary.data()) + v_binary.size()) == j_binary);
+
+        // a truncated payload must still be reported as an error
+        if (len > 16)
+        {
+            std::vector<std::uint8_t> truncated = v_string;
+            truncated.resize(truncated.size() - 8);
+            json _;
+            CHECK_THROWS_AS(_ = json::from_bson(truncated), json::parse_error);
+        }
+    }
+}

tests/src/unit-cbor.cpp

@@ -1699,7 +1699,7 @@ TEST_CASE("CBOR")
             CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0xA1, 0x61, 0X61})), "[json.exception.parse_error.110] parse error at byte 4: syntax error while parsing CBOR value: unexpected end of input", json::parse_error&);
             CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0xBF, 0x61, 0X61})), "[json.exception.parse_error.110] parse error at byte 4: syntax error while parsing CBOR value: unexpected end of input", json::parse_error&);
             CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0x5F})), "[json.exception.parse_error.110] parse error at byte 2: syntax error while parsing CBOR binary: unexpected end of input", json::parse_error&);
-            CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0x5F, 0x00})), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing CBOR binary: expected length specification (0x40-0x5B) or indefinite binary array type (0x5F); last byte: 0x00", json::parse_error&);
+            CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0x5F, 0x00})), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing CBOR binary: expected length specification (0x40-0x5B); last byte: 0x00", json::parse_error&);
             CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0x41})), "[json.exception.parse_error.110] parse error at byte 2: syntax error while parsing CBOR binary: unexpected end of input", json::parse_error&);
 
             CHECK(json::from_cbor(std::vector<uint8_t>({0x18}), true, false).is_discarded());
@@ -2305,22 +2305,21 @@ TEST_CASE("CBOR indefinite-length strings do not recurse per chunk")
 {
     // Reading an indefinite-length string or byte array used to call itself
     // once per chunk, so a payload of repeated 0x7F (or 0x5F) bytes exhausted
-    // the call stack before any of the input was rejected. The open levels are
-    // counted now, and the levels below prove the reader still reads the same
-    // values and reports the same errors at the same byte offsets.
+    // the call stack before any of the input was rejected. Nested indefinite
+    // chunks are now rejected at the second byte, without recursing.
     json _;
 
-    SECTION("many open levels are reported, not crashed on")
+    SECTION("nested levels are rejected, not crashed on")
     {
         const std::vector<uint8_t> input(200000, 0x7F);
-        CHECK_THROWS_WITH_AS(_ = json::from_cbor(input), "[json.exception.parse_error.110] parse error at byte 200001: syntax error while parsing CBOR string: unexpected end of input", json::parse_error&);
+        CHECK_THROWS_WITH_AS(_ = json::from_cbor(input), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing CBOR string: indefinite-length string is not allowed inside indefinite-length string; last byte: 0x7F", json::parse_error&);
         CHECK(json::from_cbor(input, true, false).is_discarded());
     }
 
-    SECTION("many open levels are reported, not crashed on (binary)")
+    SECTION("nested levels are rejected, not crashed on (binary)")
     {
         const std::vector<uint8_t> input(200000, 0x5F);
-        CHECK_THROWS_WITH_AS(_ = json::from_cbor(input), "[json.exception.parse_error.110] parse error at byte 200001: syntax error while parsing CBOR binary: unexpected end of input", json::parse_error&);
+        CHECK_THROWS_WITH_AS(_ = json::from_cbor(input), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing CBOR binary: indefinite-length binary array is not allowed inside indefinite-length binary array; last byte: 0x5F", json::parse_error&);
         CHECK(json::from_cbor(input, true, false).is_discarded());
     }
 
@@ -2328,22 +2327,22 @@ TEST_CASE("CBOR indefinite-length strings do not recurse per chunk")
     {
         CHECK(json::from_cbor(std::vector<uint8_t>({0x7F, 0xFF})) == json(""));
         CHECK(json::from_cbor(std::vector<uint8_t>({0x7F, 0x61, 0x61, 0xFF})) == json("a"));
-        // nested indefinite-length strings are concatenated across levels
-        CHECK(json::from_cbor(std::vector<uint8_t>({0x7F, 0x7F, 0x61, 0x61, 0xFF, 0x61, 0x62, 0xFF})) == json("ab"));
-        CHECK(json::from_cbor(std::vector<uint8_t>({0x7F, 0x7F, 0x7F, 0x61, 0x7A, 0xFF, 0xFF, 0xFF})) == json("z"));
+        // empty and nonempty definite-length chunks concatenate in order
+        CHECK(json::from_cbor(std::vector<uint8_t>({0x7F, 0x61, 'a', 0x60, 0x61, 'b', 0x61, 'c', 0xFF})) == json("abc"));
         CHECK(json::from_cbor(std::vector<uint8_t>({0xA1, 0x7F, 0x61, 0x61, 0xFF, 0x01})) == json({{"a", 1}}));
     }
 
     SECTION("chunks are still concatenated (binary)")
     {
         CHECK(json::from_cbor(std::vector<uint8_t>({0x5F, 0x41, 0x61, 0xFF})) == json::binary({0x61}));
-        CHECK(json::from_cbor(std::vector<uint8_t>({0x5F, 0x5F, 0x41, 0x61, 0xFF, 0x41, 0x62, 0xFF})) == json::binary({0x61, 0x62}));
+        CHECK(json::from_cbor(std::vector<uint8_t>({0x5F, 0xFF})) == json::binary({}));
+        CHECK(json::from_cbor(std::vector<uint8_t>({0x5F, 0x41, 0x61, 0x40, 0x41, 0x62, 0x41, 0x63, 0xFF})) == json::binary({0x61, 0x62, 0x63}));
     }
 
     SECTION("a chunk that is not a string is still rejected")
     {
-        CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0x7F, 0x7F, 0x00})), "[json.exception.parse_error.113] parse error at byte 3: syntax error while parsing CBOR string: expected length specification (0x60-0x7B) or indefinite string type (0x7F); last byte: 0x00", json::parse_error&);
-        CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0x5F, 0x5F, 0x00})), "[json.exception.parse_error.113] parse error at byte 3: syntax error while parsing CBOR binary: expected length specification (0x40-0x5B) or indefinite binary array type (0x5F); last byte: 0x00", json::parse_error&);
+        CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0x7F, 0x00})), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing CBOR string: expected length specification (0x60-0x7B); last byte: 0x00", json::parse_error&);
+        CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0x5F, 0x00})), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing CBOR binary: expected length specification (0x40-0x5B); last byte: 0x00", json::parse_error&);
     }
 
     SECTION("a break marker outside an indefinite-length string is not a string")
@@ -2896,9 +2895,17 @@ TEST_CASE("examples from RFC 8949 Appendix A")
     {
         const auto packed = utils::read_binary_file(TEST_DATA_DIRECTORY "/binary_data/cbor_binary.cbor");
         json j;
-        CHECK_NOTHROW(j = json::from_cbor(packed));
+        // the fixture's tail contains nested indefinite-length byte strings.
+        CHECK_THROWS_WITH_AS(j = json::from_cbor(packed), "[json.exception.parse_error.113] parse error at byte 513: syntax error while parsing CBOR binary: indefinite-length binary array is not allowed inside indefinite-length binary array; last byte: 0x5F", json::parse_error&);
 
-        const auto expected = utils::read_binary_file(TEST_DATA_DIRECTORY "/binary_data/cbor_binary.out");
+        // keep the byte-for-byte decoding check for its valid prefix: the first
+        // 512 encoded bytes contain 468 payload bytes in definite-length chunks.
+        auto valid_prefix = packed;
+        valid_prefix.resize(512);
+        valid_prefix.push_back(0xFF);
+        auto expected = utils::read_binary_file(TEST_DATA_DIRECTORY "/binary_data/cbor_binary.out");
+        expected.resize(468);
+        CHECK_NOTHROW(j = json::from_cbor(valid_prefix));
         CHECK(j == json::binary(expected));
 
         // 0xd8

tests/src/unit-diagnostics-optimized.cpp

@@ -0,0 +1,80 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  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
+
+// Regression test for https://github.com/nlohmann/json/issues/5742: with
+// JSON_DIAGNOSTICS, GCC (12 to at least 16) reported a false -Warray-bounds
+// error in the inlined set_parents() at -O3. The type of a new string was set
+// before the string was allocated, so GCC had to assume that operator new
+// could change it again and checked the object branch of set_parents()
+// against the string's allocation. Setting the type after creating the value
+// avoids this. The warning depends on GCC's inlining decisions, so the
+// sections cover two patterns that trigger it on different GCC versions
+// (#4819 and #5742).
+// On GCC, this file is compiled with -O3 -Werror=array-bounds (see
+// tests/CMakeLists.txt), so the test fails to build if the warning returns.
+
+#include "doctest_compatibility.h"
+
+#ifdef JSON_DIAGNOSTICS
+    #undef JSON_DIAGNOSTICS
+#endif
+
+#define JSON_DIAGNOSTICS 1
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <algorithm>
+#include <iterator>
+#include <utility>
+#include <vector>
+
+namespace
+{
+enum class diag_color
+{
+    red,
+    green,
+    blue
+};
+
+void to_json(json& j, const diag_color& c)
+{
+    static const std::pair<diag_color, json> m[] = // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+    {
+        {diag_color::red, "r"},
+        {diag_color::green, "g"},
+        {diag_color::blue, "b"},
+    };
+    const auto* it = std::find_if(std::begin(m), std::end(m), [c](const std::pair<diag_color, json>& p)
+    {
+        return p.first == c;
+    });
+    j = it->second;
+}
+} // namespace
+
+TEST_CASE("diagnostics with optimization")
+{
+    SECTION("issue #4819 - object in vector")
+    {
+        std::vector<json> jsons{};
+        jsons.emplace_back(json({{"key", "value"}}));
+        CHECK(jsons.back()["key"] == "value");
+    }
+
+    SECTION("issue #5742 - string values from a static table")
+    {
+        json j = json::array();
+        j.push_back(diag_color::red);
+        j.push_back(diag_color::green);
+        j.push_back(diag_color::blue);
+        CHECK(j.dump() == R"(["r","g","b"])");
+        CHECK_THROWS_WITH_AS(j[1].get<int>(), "[json.exception.type_error.302] (/1) type must be number, but is string", json::type_error);
+    }
+}

tests/src/unit-msgpack-cpp17.cpp

@@ -0,0 +1,99 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  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
+
+// This file contains the C++17-only part of unit-msgpack.cpp (std::byte
+// input). It is kept in a separate translation unit so the (much larger)
+// unit-msgpack.cpp does not need to be compiled and run a second time just
+// for this one test case (#5418).
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#ifdef JSON_HAS_CPP_17
+#include <cstddef>
+#include <vector>
+
+// Test suite for verifying MessagePack handling with std::byte input
+TEST_CASE("MessagePack with std::byte")
+{
+
+    SECTION("std::byte compatibility")
+    {
+        SECTION("vector roundtrip")
+        {
+            json original =
+            {
+                {"name", "test"},
+                {"value", 42},
+                {"array", {1, 2, 3}}
+            };
+
+            std::vector<uint8_t> temp = json::to_msgpack(original);
+            // Convert the uint8_t vector to std::byte vector
+            std::vector<std::byte> msgpack_data(temp.size());
+            for (size_t i = 0; i < temp.size(); ++i)
+            {
+                msgpack_data[i] = std::byte(temp[i]);
+            }
+            // Deserialize from std::byte vector back to JSON
+            json from_bytes;
+            CHECK_NOTHROW(from_bytes = json::from_msgpack(msgpack_data));
+
+            CHECK(from_bytes == original);
+        }
+
+        SECTION("empty vector")
+        {
+            const std::vector<std::byte> empty_data;
+            CHECK_THROWS_WITH_AS([&]()
+            {
+                [[maybe_unused]] auto result = json::from_msgpack(empty_data);
+                return true;
+            }
+            (),
+            "[json.exception.parse_error.110] parse error at byte 1: syntax error while parsing MessagePack value: unexpected end of input",
+            json::parse_error&);
+        }
+
+        SECTION("comparison with workaround")
+        {
+            json original =
+            {
+                {"string", "hello"},
+                {"integer", 42},
+                {"float", 3.14},
+                {"boolean", true},
+                {"null", nullptr},
+                {"array", {1, 2, 3}},
+                {"object", {{"key", "value"}}}
+            };
+
+            std::vector<uint8_t> temp = json::to_msgpack(original);
+
+            std::vector<std::byte> msgpack_data(temp.size());
+            for (size_t i = 0; i < temp.size(); ++i)
+            {
+                msgpack_data[i] = std::byte(temp[i]);
+            }
+            // Attempt direct deserialization using std::byte input
+            const json direct_result = json::from_msgpack(msgpack_data);
+
+            // Test the workaround approach: reinterpret as unsigned char* and use iterator range
+            const auto* const char_start = reinterpret_cast<unsigned char const*>(msgpack_data.data());
+            const auto* const char_end = char_start + msgpack_data.size();
+            json workaround_result = json::from_msgpack(char_start, char_end);
+
+            // Verify that the final deserialized JSON matches the original JSON
+            CHECK(direct_result == workaround_result);
+            CHECK(direct_result == original);
+        }
+    }
+}
+#endif

tests/src/unit-msgpack.cpp

@@ -2173,85 +2173,6 @@ TEST_CASE("MessagePack roundtrips" * doctest::skip())
     }
 }
 
-#ifdef JSON_HAS_CPP_17
-// Test suite for verifying MessagePack handling with std::byte input
-TEST_CASE("MessagePack with std::byte")
-{
-
-    SECTION("std::byte compatibility")
-    {
-        SECTION("vector roundtrip")
-        {
-            json original =
-            {
-                {"name", "test"},
-                {"value", 42},
-                {"array", {1, 2, 3}}
-            };
-
-            std::vector<uint8_t> temp = json::to_msgpack(original);
-            // Convert the uint8_t vector to std::byte vector
-            std::vector<std::byte> msgpack_data(temp.size());
-            for (size_t i = 0; i < temp.size(); ++i)
-            {
-                msgpack_data[i] = std::byte(temp[i]);
-            }
-            // Deserialize from std::byte vector back to JSON
-            json from_bytes;
-            CHECK_NOTHROW(from_bytes = json::from_msgpack(msgpack_data));
-
-            CHECK(from_bytes == original);
-        }
-
-        SECTION("empty vector")
-        {
-            const std::vector<std::byte> empty_data;
-            CHECK_THROWS_WITH_AS([&]()
-            {
-                [[maybe_unused]] auto result = json::from_msgpack(empty_data);
-                return true;
-            }
-            (),
-            "[json.exception.parse_error.110] parse error at byte 1: syntax error while parsing MessagePack value: unexpected end of input",
-            json::parse_error&);
-        }
-
-        SECTION("comparison with workaround")
-        {
-            json original =
-            {
-                {"string", "hello"},
-                {"integer", 42},
-                {"float", 3.14},
-                {"boolean", true},
-                {"null", nullptr},
-                {"array", {1, 2, 3}},
-                {"object", {{"key", "value"}}}
-            };
-
-            std::vector<uint8_t> temp = json::to_msgpack(original);
-
-            std::vector<std::byte> msgpack_data(temp.size());
-            for (size_t i = 0; i < temp.size(); ++i)
-            {
-                msgpack_data[i] = std::byte(temp[i]);
-            }
-            // Attempt direct deserialization using std::byte input
-            const json direct_result = json::from_msgpack(msgpack_data);
-
-            // Test the workaround approach: reinterpret as unsigned char* and use iterator range
-            const auto* const char_start = reinterpret_cast<unsigned char const*>(msgpack_data.data());
-            const auto* const char_end = char_start + msgpack_data.size();
-            json workaround_result = json::from_msgpack(char_start, char_end);
-
-            // Verify that the final deserialized JSON matches the original JSON
-            CHECK(direct_result == workaround_result);
-            CHECK(direct_result == original);
-        }
-    }
-}
-#endif
-
 // the fake sizes below do not fit into a 32-bit std::size_t
 // with clang and libstdc++ 10, the std::filesystem::path conversion that
 // C++17 builds consider for every string type is ambiguous for a class
@@ -2561,3 +2482,43 @@ TEST_CASE("MessagePack numbers use the active union member (see #5644)")
         CHECK(json::from_msgpack(result) == j);
     }
 }
+
+TEST_CASE("MessagePack large strings and binaries (chunked reader)")
+{
+    // get_msgpack_string()/get_msgpack_binary() both read through get_binary(),
+    // which reads in bounded chunks (binary_reader.hpp, chunk_size == 4096);
+    // make sure roundtripping is correct for lengths around and beyond that
+    // chunk size, for both vector (iterator) and pointer inputs.
+    for (const std::size_t len :
+            {
+                std::size_t{0}, std::size_t{1}, std::size_t{4095}, std::size_t{4096},
+                std::size_t{4097}, std::size_t{8192}, std::size_t{100000}
+            })
+    {
+        CAPTURE(len)
+
+        // string
+        const json j_string = std::string(len, 'x');
+        const std::vector<std::uint8_t> v_string = json::to_msgpack(j_string);
+        CHECK(json::from_msgpack(v_string) == j_string);
+        // pointer input exercises the std::memcpy fast path
+        CHECK(json::from_msgpack(reinterpret_cast<const char*>(v_string.data()),
+                                 reinterpret_cast<const char*>(v_string.data()) + v_string.size()) == j_string);
+
+        // binary
+        const json j_binary = json::binary(std::vector<std::uint8_t>(len, 0xCD));
+        const std::vector<std::uint8_t> v_binary = json::to_msgpack(j_binary);
+        CHECK(json::from_msgpack(v_binary) == j_binary);
+        CHECK(json::from_msgpack(reinterpret_cast<const char*>(v_binary.data()),
+                                 reinterpret_cast<const char*>(v_binary.data()) + v_binary.size()) == j_binary);
+
+        // a truncated payload must still be reported as an error
+        if (len > 16)
+        {
+            std::vector<std::uint8_t> truncated = v_string;
+            truncated.resize(truncated.size() - 8);
+            json _;
+            CHECK_THROWS_AS(_ = json::from_msgpack(truncated), json::parse_error);
+        }
+    }
+}

tests/src/unit-regression3.cpp

@@ -533,7 +533,7 @@ TEST_CASE("regression tests 3")
     }
 #endif
 
-#if JSON_HAS_RANGES && !defined(__MINGW32__)
+#if JSON_HAS_RANGE_VIEW_CONVERSION
     SECTION("issue #4916 - constructing array from C++20 ranges view does not work")
     {
         std::vector<int> nums{1, 2, 37, 42, 21};
@@ -548,7 +548,7 @@ TEST_CASE("regression tests 3")
 #endif
 
     // owning_view is not available in libstdc++ < 12
-#if JSON_HAS_RANGES && !defined(__MINGW32__) && !(defined(__GLIBCXX__) && _GLIBCXX_RELEASE < 12)
+#if JSON_HAS_RANGE_VIEW_CONVERSION && !(defined(__GLIBCXX__) && _GLIBCXX_RELEASE < 12)
     SECTION("issue #4916 - constructing array from prvalue C++20 ranges view (owning_view)")
     {
         json const j(std::vector<int> {1, 2, 37, 42, 21} | std::views::filter([](int i)
@@ -560,7 +560,7 @@ TEST_CASE("regression tests 3")
     }
 #endif
 
-#if JSON_HAS_RANGES && !defined(__MINGW32__)
+#if JSON_HAS_RANGE_VIEW_CONVERSION
     SECTION("issue #4916 - constructing array from C++20 transform view (prvalue elements)")
     {
         std::vector<int> nums{1, 2, 3};
@@ -862,6 +862,46 @@ TEST_CASE("issue #5338 - truncated CBOR tagged binary subtype is rejected")
     }
 }
 
+TEST_CASE("issue #5676 - SAX parsing of CBOR tags")
+{
+    const json expected = json::binary({1, 2, 3}, 42);
+    const auto cbor = json::to_cbor(expected);
+
+    nlohmann::detail::json_sax_acceptor<json> acceptor;
+    CHECK_FALSE(json::sax_parse(cbor, &acceptor, json::input_format_t::cbor));
+    CHECK_FALSE(json::sax_parse(cbor, &acceptor, json::input_format_t::cbor,
+                                true, false, false, json::cbor_tag_handler_t::error));
+
+    CHECK(json::sax_parse(cbor, &acceptor, json::input_format_t::cbor,
+                          true, false, false, json::cbor_tag_handler_t::ignore));
+
+    json parsed;
+    nlohmann::detail::json_sax_dom_parser<json, nlohmann::detail::string_input_adapter_type> sax(parsed);
+    CHECK(json::sax_parse(cbor, &sax, json::input_format_t::cbor,
+                          true, false, false, json::cbor_tag_handler_t::store));
+    CHECK(parsed == expected);
+
+    json iterator_parsed;
+    nlohmann::detail::json_sax_dom_parser<json, nlohmann::detail::string_input_adapter_type> iterator_sax(iterator_parsed);
+    CHECK(json::sax_parse(cbor.begin(), cbor.end(), &iterator_sax, json::input_format_t::cbor,
+                          true, false, false, json::cbor_tag_handler_t::store));
+    CHECK(iterator_parsed == expected);
+
+    json span_parsed;
+    nlohmann::detail::json_sax_dom_parser<json, nlohmann::detail::string_input_adapter_type> span_sax(span_parsed);
+    CHECK(json::sax_parse(nlohmann::detail::span_input_adapter(cbor.data(), cbor.size()), &span_sax,
+                          json::input_format_t::cbor, true, false, false, json::cbor_tag_handler_t::store));
+    CHECK(span_parsed == expected);
+
+    const std::string text = "null";
+    CHECK(json::sax_parse(text, &acceptor, json::input_format_t::json,
+                          true, false, false, json::cbor_tag_handler_t::store));
+    CHECK(json::sax_parse(text.begin(), text.end(), &acceptor, json::input_format_t::json,
+                          true, false, false, json::cbor_tag_handler_t::store));
+    CHECK(json::sax_parse(nlohmann::detail::span_input_adapter(text.data(), text.size()), &acceptor,
+                          json::input_format_t::json, true, false, false, json::cbor_tag_handler_t::store));
+}
+
 TEST_CASE("issue #5402 - update(merge_objects=true) overwrites a primitive with an object")
 {
     json t = {{"k", 1}};
@@ -920,4 +960,12 @@ TEST_CASE("regression test #5476 - array type without reserve()")
     }
 }
 
+TEST_CASE("issue #5317 - nested indefinite-length CBOR string chunks are rejected")
+{
+    json _;
+    CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<std::uint8_t>({0x7F, 0x7F, 0x61, 0x61, 0xFF, 0xFF})), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing CBOR string: indefinite-length string is not allowed inside indefinite-length string; last byte: 0x7F", json::parse_error&);
+    CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<std::uint8_t>({0x5F, 0x5F, 0x41, 0x61, 0xFF, 0xFF})), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing CBOR binary: indefinite-length binary array is not allowed inside indefinite-length binary array; last byte: 0x5F", json::parse_error&);
+    CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<std::uint8_t>({0xA1, 0x7F, 0x7F, 0xFF, 0xFF, 0x01})), "[json.exception.parse_error.113] parse error at byte 3: syntax error while parsing CBOR string: indefinite-length string is not allowed inside indefinite-length string; last byte: 0x7F", json::parse_error&);
+}
+
 DOCTEST_CLANG_SUPPRESS_WARNING_POP

tests/src/unit-serialization.cpp

@@ -809,3 +809,178 @@ TEST_CASE("serializer buffers are flushed mid-string and mid-binary")
         CHECK(j.dump(2) == "{\n  \"bytes\": [" + expected_pretty_bytes + "],\n  \"subtype\": null\n}");
     }
 }
+
+TEST_CASE("serialization boundary values for the write buffer")
+{
+    // write_buffer is a std::array<char, 1024> (write_buffer_size). put_string()
+    // guards it with two checks, and each must be exercised exactly on and one
+    // past its own boundary: a heap overflow in a different manual buffer path
+    // (the dump(1100) indent buffer) once survived 100% line coverage because
+    // every test that touched it only ever grew the buffer by a single step,
+    // never landing on the exact edge of the comparison that protects it.
+    //
+    // - straight-through: put_string() bypasses write_buffer entirely and
+    //   writes directly to the output adapter once `length >= write_buffer.size()`.
+    // - flush-then-copy: otherwise, if `write_buffer_pos + length > write_buffer.size()`,
+    //   put_string() flushes what is pending and then memcpy's the new run into
+    //   the freshly emptied buffer.
+
+    SECTION("top-level string exercises the straight-through guard (length >= 1024)")
+    {
+        // dump() of a bare string writes the opening quote with put_char()
+        // (write_buffer_pos: 0 -> 1), then the body with put_string(). With
+        // write_buffer_pos == 1, `1 + length > 1024` and `length >= 1024` flip
+        // together at length 1024, so 1023/1024/1025 cover "just under",
+        // "exactly at" and "just over" the guard in one move: 1023 is copied
+        // into the buffer (filling it exactly), 1024 and 1025 bypass it.
+        for (const std::size_t len :
+                {
+                    std::size_t{1023}, std::size_t{1024}, std::size_t{1025}
+                })
+        {
+            CAPTURE(len)
+            const std::string body(len, 'a');
+            const json j = body;
+            const std::string expected = '"' + body + '"';
+
+            CHECK(j.dump() == expected);
+
+            std::ostringstream o;
+            o << j;
+            CHECK(o.str() == expected);
+        }
+    }
+
+    SECTION("string nested in an array exercises the flush-then-copy guard")
+    {
+        // json::array({body}) writes '[' then '"' before the body, so
+        // write_buffer_pos == 2 when put_string() is entered for it. The
+        // body's last byte then lands at logical offset 2 + len: len == 1022
+        // lands exactly on offset 1024 (2 + 1022 == write_buffer.size(), so the
+        // strict "> " guard does not fire and the body fits snugly), while
+        // len == 1023 lands one past it at offset 1025 (2 + 1023 > 1024),
+        // which must flush what's pending before copying the body in.
+        for (const std::size_t len :
+                {
+                    std::size_t{1022}, std::size_t{1023}
+                })
+        {
+            CAPTURE(len)
+            const std::string body(len, 'a');
+            const json j = json::array({body});
+            const std::string expected = "[\"" + body + "\"]";
+
+            CHECK(j.dump() == expected);
+
+            std::ostringstream o;
+            o << j;
+            CHECK(o.str() == expected);
+
+            CHECK(json::parse(j.dump()) == j);
+        }
+    }
+}
+
+TEST_CASE("serialization boundary values for the string buffer")
+{
+    // string_buffer is a std::array<char, 512>. dump_escaped_impl() flushes it
+    // mid-string once fewer than 13 bytes remain (`string_buffer.size() - bytes
+    // < 13`), 13 being one more than the most a single code point can ever
+    // write at once (a surrogate pair: two back-to-back "\uXXXX" escapes, 12
+    // bytes). Every write into string_buffer that this check protects happens
+    // in steps of 2 (a simple "\\x" escape) or 6 (one "\uXXXX" unit), so
+    // `bytes` only ever takes even values at the point the check runs - the
+    // tightest values actually reachable are therefore 498 (512 - 498 == 14,
+    // one simple escape away from the threshold) and 500 (512 - 500 == 12,
+    // where the flush fires immediately and resets bytes to 0).
+
+    SECTION("a run of 2-byte escapes lands bytes on, and one step past, the flush threshold")
+    {
+        for (const int count :
+                {
+                    249, 250, 251
+                })
+        {
+            CAPTURE(count)
+            const json j = std::string(static_cast<std::size_t>(count), '\n');
+            std::string expected = "\"";
+            for (int i = 0; i < count; ++i)
+            {
+                expected += "\\n";
+            }
+            expected += '"';
+            CHECK(j.dump() == expected);
+        }
+    }
+
+    SECTION("an ASCII prefix leaves the tightest reachable margin before a 12-byte surrogate pair")
+    {
+        // U+1F600 (the "\xF0\x9F\x98\x80" UTF-8 bytes) is dumped under
+        // ensure_ascii as the 12-byte surrogate pair "\ud83d\ude00"; that
+        // write happens in a single step with no intermediate flush check, so
+        // it is the write most exposed by an off-by-one in the "< 13" guard.
+        // A prefix of 249 newlines leaves exactly 14 bytes of headroom
+        // (512 - 498), the smallest margin the guard ever actually allows
+        // into a new code point; 250 newlines instead trigger the guard's own
+        // flush first, so the emoji starts from a freshly emptied (512-byte)
+        // buffer, and 251 repeats that with one more escape already past the
+        // reset. Together they cover the margin the guard allows landing on,
+        // one step before, and one step after - all must still produce the
+        // identical, correct escapes.
+        for (const int prefix_count :
+                {
+                    249, 250, 251
+                })
+        {
+            CAPTURE(prefix_count)
+            const std::string prefix(static_cast<std::size_t>(prefix_count), '\n');
+            const std::string emoji = "\xF0\x9F\x98\x80";
+            const json j = prefix + emoji;
+
+            std::string expected_prefix;
+            for (int i = 0; i < prefix_count; ++i)
+            {
+                expected_prefix += "\\n";
+            }
+
+            // newline escaping does not depend on ensure_ascii: only the
+            // emoji differs (raw UTF-8 bytes vs. a \u-escaped surrogate pair)
+            CHECK(j.dump(-1, ' ', false) == '"' + expected_prefix + emoji + '"');
+            CHECK(j.dump(-1, ' ', true) == '"' + expected_prefix + "\\ud83d\\ude00\"");
+            CHECK(json::parse(j.dump(-1, ' ', true)) == j);
+            CHECK(json::parse(j.dump(-1, ' ', false)) == j);
+        }
+    }
+
+    SECTION("SWAR bulk-copy stride: k plain bytes followed by a byte handled individually")
+    {
+        // string_bulk_run()/find_ascii_copyable_run() (string_scan.hpp) scan 8
+        // bytes at a time and fall back to a byte-at-a-time tail scan for
+        // what is left over. k from 0 to 17 spans zero, one and two full
+        // 8-byte strides plus a 1-byte tail, so every possible stopping point
+        // within and right after the SIMD stride is covered.
+        for (std::size_t k = 0; k <= 17; ++k)
+        {
+            CAPTURE(k)
+            const std::string prefix(k, 'a');
+
+            // (a) the run is stopped by a quote that must itself be escaped
+            {
+                const json j = prefix + "\"";
+                CHECK(j.dump() == '"' + prefix + "\\\"" + '"');
+            }
+
+            // (b) the run is stopped by a control character
+            {
+                const json j = prefix + "\x01";
+                CHECK(j.dump() == '"' + prefix + "\\u0001" + '"');
+            }
+
+            // (c) the run is stopped by a non-ASCII byte under ensure_ascii
+            {
+                const json j = prefix + "\xC3\xA9"; // prefix + 'é'
+                CHECK(j.dump(-1, ' ', true) == '"' + prefix + "\\u00e9" + '"');
+            }
+        }
+    }
+}

tests/src/unit-ubjson.cpp

@@ -3308,3 +3308,43 @@ TEST_CASE("UBJSON and BJData integer markers at every range edge")
         }
     }
 }
+
+TEST_CASE("UBJSON large strings (chunked reader)")
+{
+    // get_ubjson_string() reads through get_string(), which reads in bounded
+    // chunks (binary_reader.hpp, chunk_size == 4096); make sure roundtripping
+    // is correct for lengths around and beyond that chunk size, for both
+    // vector (iterator) and pointer inputs.
+    //
+    // A binary value is not included here: plain UBJSON (unlike BJData, see
+    // the "BJData large strings and binaries" test) has no reader-side binary
+    // type, so even the optimized uint8_t-array encoding of a binary value is
+    // read back element-by-element as a JSON array of numbers rather than
+    // through get_binary() - it never reaches the chunked path this test is
+    // about (see the "roundtrip only works to an array of numbers" case
+    // above).
+    for (const std::size_t len :
+            {
+                std::size_t{0}, std::size_t{1}, std::size_t{4095}, std::size_t{4096},
+                std::size_t{4097}, std::size_t{8192}, std::size_t{100000}
+            })
+    {
+        CAPTURE(len)
+
+        const json j_string = std::string(len, 'x');
+        const std::vector<std::uint8_t> v_string = json::to_ubjson(j_string);
+        CHECK(json::from_ubjson(v_string) == j_string);
+        // pointer input exercises the std::memcpy fast path
+        CHECK(json::from_ubjson(reinterpret_cast<const char*>(v_string.data()),
+                                reinterpret_cast<const char*>(v_string.data()) + v_string.size()) == j_string);
+
+        // a truncated payload must still be reported as an error
+        if (len > 16)
+        {
+            std::vector<std::uint8_t> truncated = v_string;
+            truncated.resize(truncated.size() - 8);
+            json _;
+            CHECK_THROWS_AS(_ = json::from_ubjson(truncated), json::parse_error);
+        }
+    }
+}

tests/src/unit-unicode1.cpp

@@ -1,623 +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
-
-#include "doctest_compatibility.h"
-
-// for some reason including this after the json header leads to linker errors with VS 2017...
-#include <locale>
-#include <nlohmann/json.hpp>
-using nlohmann::json;
-
-#include <fstream>
-#include <sstream>
-#include <iomanip>
-#include "make_test_data_available.hpp"
-#include "test_utils.hpp"
-
-TEST_CASE("Unicode (1/5)" * doctest::skip())
-{
-    SECTION("\\uxxxx sequences")
-    {
-        // create an escaped string from a code point
-        const auto codepoint_to_unicode = [](std::size_t cp)
-        {
-            // code points are represented as a six-character sequence: a
-            // reverse solidus, followed by the lowercase letter u, followed
-            // by four hexadecimal digits that encode the character's code
-            // point
-            std::stringstream ss;
-            ss << "\\u" << std::setw(4) << std::setfill('0') << std::hex << cp;
-            return ss.str();
-        };
-
-        SECTION("correct sequences")
-        {
-            // generate all UTF-8 code points; in total, 1112064 code points are
-            // generated: 0x1FFFFF code points - 2048 invalid values between
-            // 0xD800 and 0xDFFF.
-            for (std::size_t cp = 0; cp <= 0x10FFFFu; ++cp)
-            {
-                // string to store the code point as in \uxxxx format
-                std::string json_text = "\"";
-
-                // decide whether to use one or two \uxxxx sequences
-                if (cp < 0x10000u)
-                {
-                    // The Unicode standard permanently reserves these code point
-                    // values for UTF-16 encoding of the high and low surrogates, and
-                    // they will never be assigned a character, so there should be no
-                    // reason to encode them. The official Unicode standard says that
-                    // no UTF forms, including UTF-16, can encode these code points.
-                    if (cp >= 0xD800u && cp <= 0xDFFFu)
-                    {
-                        // if we would not skip these code points, we would get a
-                        // "missing low surrogate" exception
-                        continue;
-                    }
-
-                    // code points in the Basic Multilingual Plane can be
-                    // represented with one \uxxxx sequence
-                    json_text += codepoint_to_unicode(cp);
-                }
-                else
-                {
-                    // To escape an extended character that is not in the Basic
-                    // Multilingual Plane, the character is represented as a
-                    // 12-character sequence, encoding the UTF-16 surrogate pair
-                    const auto codepoint1 = 0xd800u + (((cp - 0x10000u) >> 10) & 0x3ffu);
-                    const auto codepoint2 = 0xdc00u + ((cp - 0x10000u) & 0x3ffu);
-                    json_text += codepoint_to_unicode(codepoint1) + codepoint_to_unicode(codepoint2);
-                }
-
-                json_text += "\"";
-                CAPTURE(json_text)
-                json _;
-                CHECK_NOTHROW(_ = json::parse(json_text));
-            }
-        }
-
-        SECTION("incorrect sequences")
-        {
-            SECTION("incorrect surrogate values")
-            {
-                json _;
-
-                CHECK_THROWS_WITH_AS(_ = json::parse("\"\\uDC00\\uDC00\""), "[json.exception.parse_error.101] parse error at line 1, column 7: syntax error while parsing value - invalid string: surrogate U+DC00..U+DFFF must follow U+D800..U+DBFF; last read: '\"\\uDC00'", json::parse_error&);
-
-                CHECK_THROWS_WITH_AS(_ = json::parse("\"\\uD7FF\\uDC00\""), "[json.exception.parse_error.101] parse error at line 1, column 13: syntax error while parsing value - invalid string: surrogate U+DC00..U+DFFF must follow U+D800..U+DBFF; last read: '\"\\uD7FF\\uDC00'", json::parse_error&);
-
-                CHECK_THROWS_WITH_AS(_ = json::parse("\"\\uD800]\""), "[json.exception.parse_error.101] parse error at line 1, column 8: syntax error while parsing value - invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF; last read: '\"\\uD800]'", json::parse_error&);
-
-                CHECK_THROWS_WITH_AS(_ = json::parse("\"\\uD800\\v\""), "[json.exception.parse_error.101] parse error at line 1, column 9: syntax error while parsing value - invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF; last read: '\"\\uD800\\v'", json::parse_error&);
-
-                CHECK_THROWS_WITH_AS(_ = json::parse("\"\\uD800\\u123\""), "[json.exception.parse_error.101] parse error at line 1, column 13: syntax error while parsing value - invalid string: '\\u' must be followed by 4 hex digits; last read: '\"\\uD800\\u123\"'", json::parse_error&);
-
-                CHECK_THROWS_WITH_AS(_ = json::parse("\"\\uD800\\uDBFF\""), "[json.exception.parse_error.101] parse error at line 1, column 13: syntax error while parsing value - invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF; last read: '\"\\uD800\\uDBFF'", json::parse_error&);
-
-                CHECK_THROWS_WITH_AS(_ = json::parse("\"\\uD800\\uE000\""), "[json.exception.parse_error.101] parse error at line 1, column 13: syntax error while parsing value - invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF; last read: '\"\\uD800\\uE000'", json::parse_error&);
-            }
-        }
-
-#if 0 // NOLINT(readability-avoid-unconditional-preprocessor-if)
-        SECTION("incorrect sequences")
-        {
-            SECTION("high surrogate without low surrogate")
-            {
-                // D800..DBFF are high surrogates and must be followed by low
-                // surrogates DC00..DFFF; here, nothing follows
-                for (std::size_t cp = 0xD800u; cp <= 0xDBFFu; ++cp)
-                {
-                    std::string json_text = "\"" + codepoint_to_unicode(cp) + "\"";
-                    CAPTURE(json_text)
-                    CHECK_THROWS_AS(json::parse(json_text), json::parse_error&);
-                }
-            }
-
-            SECTION("high surrogate with wrong low surrogate")
-            {
-                // D800..DBFF are high surrogates and must be followed by low
-                // surrogates DC00..DFFF; here a different sequence follows
-                for (std::size_t cp1 = 0xD800u; cp1 <= 0xDBFFu; ++cp1)
-                {
-                    for (std::size_t cp2 = 0x0000u; cp2 <= 0xFFFFu; ++cp2)
-                    {
-                        if (0xDC00u <= cp2 && cp2 <= 0xDFFFu)
-                        {
-                            continue;
-                        }
-
-                        std::string json_text = "\"" + codepoint_to_unicode(cp1) + codepoint_to_unicode(cp2) + "\"";
-                        CAPTURE(json_text)
-                        CHECK_THROWS_AS(json::parse(json_text), json::parse_error&);
-                    }
-                }
-            }
-
-            SECTION("low surrogate without high surrogate")
-            {
-                // low surrogates DC00..DFFF must follow high surrogates; here,
-                // they occur alone
-                for (std::size_t cp = 0xDC00u; cp <= 0xDFFFu; ++cp)
-                {
-                    std::string json_text = "\"" + codepoint_to_unicode(cp) + "\"";
-                    CAPTURE(json_text)
-                    CHECK_THROWS_AS(json::parse(json_text), json::parse_error&);
-                }
-            }
-
-        }
-#endif
-    }
-
-    SECTION("read all unicode characters")
-    {
-        // read a file with all Unicode characters stored as single-character
-        // strings in a JSON array
-        std::ifstream f(TEST_DATA_DIRECTORY "/json_nlohmann_tests/all_unicode.json");
-        json j;
-        CHECK_NOTHROW(f >> j);
-
-        // the array has 1112064 + 1 elements (a terminating "null" value)
-        // Note: 1112064 = 0x1FFFFF code points - 2048 invalid values between
-        // 0xD800 and 0xDFFF.
-        CHECK(j.size() == 1112065);
-
-        SECTION("check JSON Pointers")
-        {
-            for (const auto& s : j)
-            {
-                // skip non-string JSON values
-                if (!s.is_string())
-                {
-                    continue;
-                }
-
-                auto ptr = s.get<std::string>();
-
-                // tilde must be followed by 0 or 1
-                if (ptr == "~")
-                {
-                    ptr += "0";
-                }
-
-                // JSON Pointers must begin with "/"
-                ptr.insert(0, "/");
-
-                CHECK_NOTHROW(json::json_pointer("/" + ptr));
-
-                // check escape/unescape roundtrip
-                auto escaped = nlohmann::detail::escape(ptr);
-                nlohmann::detail::unescape(escaped);
-                CHECK(escaped == ptr);
-            }
-        }
-    }
-
-    SECTION("ignore byte-order-mark")
-    {
-        SECTION("in a stream")
-        {
-            // read a file with a UTF-8 BOM
-            std::ifstream f(TEST_DATA_DIRECTORY "/json_nlohmann_tests/bom.json");
-            json j;
-            CHECK_NOTHROW(f >> j);
-        }
-
-        SECTION("with an iterator")
-        {
-            std::string i = "\xef\xbb\xbf{\n   \"foo\": true\n}";
-            json _;
-            CHECK_NOTHROW(_ = json::parse(i.begin(), i.end()));
-        }
-    }
-
-    SECTION("error for incomplete/wrong BOM")
-    {
-        json _;
-        CHECK_THROWS_AS(_ = json::parse("\xef\xbb"), json::parse_error&);
-        CHECK_THROWS_AS(_ = json::parse("\xef\xbb\xbb"), json::parse_error&);
-    }
-}
-
-namespace
-{
-void roundtrip(bool success_expected, const std::string& s);
-
-void roundtrip(bool success_expected, const std::string& s)
-{
-    CAPTURE(s)
-    json _;
-
-    // create JSON string value
-    const json j = s;
-    // create JSON text
-    const std::string ps = std::string("\"") + s + "\"";
-
-    if (success_expected)
-    {
-        // serialization succeeds
-        // dump() is nodiscard; this only checks that dumping does not throw
-        CHECK_NOTHROW(utils::ignore_return_value(j.dump()));
-
-        // exclude parse test for U+0000
-        if (s[0] != '\0')
-        {
-            // parsing JSON text succeeds
-            CHECK_NOTHROW(_ = json::parse(ps));
-        }
-
-        // roundtrip succeeds
-        CHECK_NOTHROW(_ = json::parse(j.dump()));
-
-        // after roundtrip, the same string is stored
-        const json jr = json::parse(j.dump());
-        CHECK(jr.get<std::string>() == s);
-    }
-    else
-    {
-        // serialization fails
-        // dump() is nodiscard; the exception is thrown by dump() itself before it would return
-        CHECK_THROWS_AS(utils::ignore_return_value(j.dump()), json::type_error&);
-
-        // parsing JSON text fails
-        CHECK_THROWS_AS(_ = json::parse(ps), json::parse_error&);
-    }
-}
-} // namespace
-
-TEST_CASE("Markus Kuhn's UTF-8 decoder capability and stress test")
-{
-    // Markus Kuhn <http://www.cl.cam.ac.uk/~mgk25/> - 2015-08-28 - CC BY 4.0
-    // http://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-test.txt
-
-    SECTION("1  Some correct UTF-8 text")
-    {
-        roundtrip(true, "κόσμε");
-    }
-
-    SECTION("2  Boundary condition test cases")
-    {
-        SECTION("2.1  First possible sequence of a certain length")
-        {
-            // 2.1.1  1 byte  (U-00000000)
-            roundtrip(true, std::string("\0", 1));
-            // 2.1.2  2 bytes (U-00000080)
-            roundtrip(true, "\xc2\x80");
-            // 2.1.3  3 bytes (U-00000800)
-            roundtrip(true, "\xe0\xa0\x80");
-            // 2.1.4  4 bytes (U-00010000)
-            roundtrip(true, "\xf0\x90\x80\x80");
-
-            // 2.1.5  5 bytes (U-00200000)
-            roundtrip(false, "\xF8\x88\x80\x80\x80");
-            // 2.1.6  6 bytes (U-04000000)
-            roundtrip(false, "\xFC\x84\x80\x80\x80\x80");
-        }
-
-        SECTION("2.2  Last possible sequence of a certain length")
-        {
-            // 2.2.1  1 byte  (U-0000007F)
-            roundtrip(true, "\x7f");
-            // 2.2.2  2 bytes (U-000007FF)
-            roundtrip(true, "\xdf\xbf");
-            // 2.2.3  3 bytes (U-0000FFFF)
-            roundtrip(true, "\xef\xbf\xbf");
-
-            // 2.2.4  4 bytes (U-001FFFFF)
-            roundtrip(false, "\xF7\xBF\xBF\xBF");
-            // 2.2.5  5 bytes (U-03FFFFFF)
-            roundtrip(false, "\xFB\xBF\xBF\xBF\xBF");
-            // 2.2.6  6 bytes (U-7FFFFFFF)
-            roundtrip(false, "\xFD\xBF\xBF\xBF\xBF\xBF");
-        }
-
-        SECTION("2.3  Other boundary conditions")
-        {
-            // 2.3.1  U-0000D7FF = ed 9f bf
-            roundtrip(true, "\xed\x9f\xbf");
-            // 2.3.2  U-0000E000 = ee 80 80
-            roundtrip(true, "\xee\x80\x80");
-            // 2.3.3  U-0000FFFD = ef bf bd
-            roundtrip(true, "\xef\xbf\xbd");
-            // 2.3.4  U-0010FFFF = f4 8f bf bf
-            roundtrip(true, "\xf4\x8f\xbf\xbf");
-
-            // 2.3.5  U-00110000 = f4 90 80 80
-            roundtrip(false, "\xf4\x90\x80\x80");
-        }
-    }
-
-    SECTION("3  Malformed sequences")
-    {
-        SECTION("3.1  Unexpected continuation bytes")
-        {
-            // Each unexpected continuation byte should be separately signalled as a
-            // malformed sequence of its own.
-
-            // 3.1.1  First continuation byte 0x80
-            roundtrip(false, "\x80");
-            // 3.1.2  Last  continuation byte 0xbf
-            roundtrip(false, "\xbf");
-
-            // 3.1.3  2 continuation bytes
-            roundtrip(false, "\x80\xbf");
-            // 3.1.4  3 continuation bytes
-            roundtrip(false, "\x80\xbf\x80");
-            // 3.1.5  4 continuation bytes
-            roundtrip(false, "\x80\xbf\x80\xbf");
-            // 3.1.6  5 continuation bytes
-            roundtrip(false, "\x80\xbf\x80\xbf\x80");
-            // 3.1.7  6 continuation bytes
-            roundtrip(false, "\x80\xbf\x80\xbf\x80\xbf");
-            // 3.1.8  7 continuation bytes
-            roundtrip(false, "\x80\xbf\x80\xbf\x80\xbf\x80");
-
-            // 3.1.9  Sequence of all 64 possible continuation bytes (0x80-0xbf)
-            roundtrip(false, "\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf");
-        }
-
-        SECTION("3.2  Lonely start characters")
-        {
-            // 3.2.1  All 32 first bytes of 2-byte sequences (0xc0-0xdf)
-            roundtrip(false, "\xc0 \xc1 \xc2 \xc3 \xc4 \xc5 \xc6 \xc7 \xc8 \xc9 \xca \xcb \xcc \xcd \xce \xcf \xd0 \xd1 \xd2 \xd3 \xd4 \xd5 \xd6 \xd7 \xd8 \xd9 \xda \xdb \xdc \xdd \xde \xdf");
-            // 3.2.2  All 16 first bytes of 3-byte sequences (0xe0-0xef)
-            roundtrip(false, "\xe0 \xe1 \xe2 \xe3 \xe4 \xe5 \xe6 \xe7 \xe8 \xe9 \xea \xeb \xec \xed \xee \xef");
-            // 3.2.3  All 8 first bytes of 4-byte sequences (0xf0-0xf7)
-            roundtrip(false, "\xf0 \xf1 \xf2 \xf3 \xf4 \xf5 \xf6 \xf7");
-            // 3.2.4  All 4 first bytes of 5-byte sequences (0xf8-0xfb)
-            roundtrip(false, "\xf8 \xf9 \xfa \xfb");
-            // 3.2.5  All 2 first bytes of 6-byte sequences (0xfc-0xfd)
-            roundtrip(false, "\xfc \xfd");
-        }
-
-        SECTION("3.3  Sequences with last continuation byte missing")
-        {
-            // All bytes of an incomplete sequence should be signalled as a single
-            // malformed sequence, i.e., you should see only a single replacement
-            // character in each of the next 10 tests. (Characters as in section 2)
-
-            // 3.3.1  2-byte sequence with last byte missing (U+0000)
-            roundtrip(false, "\xc0");
-            // 3.3.2  3-byte sequence with last byte missing (U+0000)
-            roundtrip(false, "\xe0\x80");
-            // 3.3.3  4-byte sequence with last byte missing (U+0000)
-            roundtrip(false, "\xf0\x80\x80");
-            // 3.3.4  5-byte sequence with last byte missing (U+0000)
-            roundtrip(false, "\xf8\x80\x80\x80");
-            // 3.3.5  6-byte sequence with last byte missing (U+0000)
-            roundtrip(false, "\xfc\x80\x80\x80\x80");
-            // 3.3.6  2-byte sequence with last byte missing (U-000007FF)
-            roundtrip(false, "\xdf");
-            // 3.3.7  3-byte sequence with last byte missing (U-0000FFFF)
-            roundtrip(false, "\xef\xbf");
-            // 3.3.8  4-byte sequence with last byte missing (U-001FFFFF)
-            roundtrip(false, "\xf7\xbf\xbf");
-            // 3.3.9  5-byte sequence with last byte missing (U-03FFFFFF)
-            roundtrip(false, "\xfb\xbf\xbf\xbf");
-            // 3.3.10 6-byte sequence with last byte missing (U-7FFFFFFF)
-            roundtrip(false, "\xfd\xbf\xbf\xbf\xbf");
-        }
-
-        SECTION("3.4  Concatenation of incomplete sequences")
-        {
-            // All the 10 sequences of 3.3 concatenated, you should see 10 malformed
-            // sequences being signalled:
-            roundtrip(false, "\xc0\xe0\x80\xf0\x80\x80\xf8\x80\x80\x80\xfc\x80\x80\x80\x80\xdf\xef\xbf\xf7\xbf\xbf\xfb\xbf\xbf\xbf\xfd\xbf\xbf\xbf\xbf");
-        }
-
-        SECTION("3.5  Impossible bytes")
-        {
-            // The following two bytes cannot appear in a correct UTF-8 string
-
-            // 3.5.1  fe
-            roundtrip(false, "\xfe");
-            // 3.5.2  ff
-            roundtrip(false, "\xff");
-            // 3.5.3  fe fe ff ff
-            roundtrip(false, "\xfe\xfe\xff\xff");
-        }
-    }
-
-    SECTION("4  Overlong sequences")
-    {
-        // The following sequences are not malformed according to the letter of
-        // the Unicode 2.0 standard. However, they are longer then necessary and
-        // a correct UTF-8 encoder is not allowed to produce them. A "safe UTF-8
-        // decoder" should reject them just like malformed sequences for two
-        // reasons: (1) It helps to debug applications if overlong sequences are
-        // not treated as valid representations of characters, because this helps
-        // to spot problems more quickly. (2) Overlong sequences provide
-        // alternative representations of characters, that could maliciously be
-        // used to bypass filters that check only for ASCII characters. For
-        // instance, a 2-byte encoded line feed (LF) would not be caught by a
-        // line counter that counts only 0x0a bytes, but it would still be
-        // processed as a line feed by an unsafe UTF-8 decoder later in the
-        // pipeline. From a security point of view, ASCII compatibility of UTF-8
-        // sequences means also, that ASCII characters are *only* allowed to be
-        // represented by ASCII bytes in the range 0x00-0x7f. To ensure this
-        // aspect of ASCII compatibility, use only "safe UTF-8 decoders" that
-        // reject overlong UTF-8 sequences for which a shorter encoding exists.
-
-        SECTION("4.1  Examples of an overlong ASCII character")
-        {
-            // With a safe UTF-8 decoder, all the following five overlong
-            // representations of the ASCII character slash ("/") should be rejected
-            // like a malformed UTF-8 sequence, for instance by substituting it with
-            // a replacement character. If you see a slash below, you do not have a
-            // safe UTF-8 decoder!
-
-            // 4.1.1 U+002F = c0 af
-            roundtrip(false, "\xc0\xaf");
-            // 4.1.2 U+002F = e0 80 af
-            roundtrip(false, "\xe0\x80\xaf");
-            // 4.1.3 U+002F = f0 80 80 af
-            roundtrip(false, "\xf0\x80\x80\xaf");
-            // 4.1.4 U+002F = f8 80 80 80 af
-            roundtrip(false, "\xf8\x80\x80\x80\xaf");
-            // 4.1.5 U+002F = fc 80 80 80 80 af
-            roundtrip(false, "\xfc\x80\x80\x80\x80\xaf");
-        }
-
-        SECTION("4.2  Maximum overlong sequences")
-        {
-            // Below you see the highest Unicode value that is still resulting in an
-            // overlong sequence if represented with the given number of bytes. This
-            // is a boundary test for safe UTF-8 decoders. All five characters should
-            // be rejected like malformed UTF-8 sequences.
-
-            // 4.2.1  U-0000007F = c1 bf
-            roundtrip(false, "\xc1\xbf");
-            // 4.2.2  U-000007FF = e0 9f bf
-            roundtrip(false, "\xe0\x9f\xbf");
-            // 4.2.3  U-0000FFFF = f0 8f bf bf
-            roundtrip(false, "\xf0\x8f\xbf\xbf");
-            // 4.2.4  U-001FFFFF = f8 87 bf bf bf
-            roundtrip(false, "\xf8\x87\xbf\xbf\xbf");
-            // 4.2.5  U-03FFFFFF = fc 83 bf bf bf bf
-            roundtrip(false, "\xfc\x83\xbf\xbf\xbf\xbf");
-        }
-
-        SECTION("4.3  Overlong representation of the NUL character")
-        {
-            // The following five sequences should also be rejected like malformed
-            // UTF-8 sequences and should not be treated like the ASCII NUL
-            // character.
-
-            // 4.3.1  U+0000 = c0 80
-            roundtrip(false, "\xc0\x80");
-            // 4.3.2  U+0000 = e0 80 80
-            roundtrip(false, "\xe0\x80\x80");
-            // 4.3.3  U+0000 = f0 80 80 80
-            roundtrip(false, "\xf0\x80\x80\x80");
-            // 4.3.4  U+0000 = f8 80 80 80 80
-            roundtrip(false, "\xf8\x80\x80\x80\x80");
-            // 4.3.5  U+0000 = fc 80 80 80 80 80
-            roundtrip(false, "\xfc\x80\x80\x80\x80\x80");
-        }
-    }
-
-    SECTION("5  Illegal code positions")
-    {
-        // The following UTF-8 sequences should be rejected like malformed
-        // sequences, because they never represent valid ISO 10646 characters and
-        // a UTF-8 decoder that accepts them might introduce security problems
-        // comparable to overlong UTF-8 sequences.
-
-        SECTION("5.1 Single UTF-16 surrogates")
-        {
-            // 5.1.1  U+D800 = ed a0 80
-            roundtrip(false, "\xed\xa0\x80");
-            // 5.1.2  U+DB7F = ed ad bf
-            roundtrip(false, "\xed\xad\xbf");
-            // 5.1.3  U+DB80 = ed ae 80
-            roundtrip(false, "\xed\xae\x80");
-            // 5.1.4  U+DBFF = ed af bf
-            roundtrip(false, "\xed\xaf\xbf");
-            // 5.1.5  U+DC00 = ed b0 80
-            roundtrip(false, "\xed\xb0\x80");
-            // 5.1.6  U+DF80 = ed be 80
-            roundtrip(false, "\xed\xbe\x80");
-            // 5.1.7  U+DFFF = ed bf bf
-            roundtrip(false, "\xed\xbf\xbf");
-        }
-
-        SECTION("5.2 Paired UTF-16 surrogates")
-        {
-            // 5.2.1  U+D800 U+DC00 = ed a0 80 ed b0 80
-            roundtrip(false, "\xed\xa0\x80\xed\xb0\x80");
-            // 5.2.2  U+D800 U+DFFF = ed a0 80 ed bf bf
-            roundtrip(false, "\xed\xa0\x80\xed\xbf\xbf");
-            // 5.2.3  U+DB7F U+DC00 = ed ad bf ed b0 80
-            roundtrip(false, "\xed\xad\xbf\xed\xb0\x80");
-            // 5.2.4  U+DB7F U+DFFF = ed ad bf ed bf bf
-            roundtrip(false, "\xed\xad\xbf\xed\xbf\xbf");
-            // 5.2.5  U+DB80 U+DC00 = ed ae 80 ed b0 80
-            roundtrip(false, "\xed\xae\x80\xed\xb0\x80");
-            // 5.2.6  U+DB80 U+DFFF = ed ae 80 ed bf bf
-            roundtrip(false, "\xed\xae\x80\xed\xbf\xbf");
-            // 5.2.7  U+DBFF U+DC00 = ed af bf ed b0 80
-            roundtrip(false, "\xed\xaf\xbf\xed\xb0\x80");
-            // 5.2.8  U+DBFF U+DFFF = ed af bf ed bf bf
-            roundtrip(false, "\xed\xaf\xbf\xed\xbf\xbf");
-        }
-
-        SECTION("5.3 Noncharacter code positions")
-        {
-            // The following "noncharacters" are "reserved for internal use" by
-            // applications, and according to older versions of the Unicode Standard
-            // "should never be interchanged". Unicode Corrigendum #9 dropped the
-            // latter restriction. Nevertheless, their presence in incoming UTF-8 data
-            // can remain a potential security risk, depending on what use is made of
-            // these codes subsequently. Examples of such internal use:
-            //
-            //  - Some file APIs with 16-bit characters may use the integer value -1
-            //    = U+FFFF to signal an end-of-file (EOF) or error condition.
-            //
-            //  - In some UTF-16 receivers, code point U+FFFE might trigger a
-            //    byte-swap operation (to convert between UTF-16LE and UTF-16BE).
-            //
-            // With such internal use of noncharacters, it may be desirable and safer
-            // to block those code points in UTF-8 decoders, as they should never
-            // occur legitimately in incoming UTF-8 data, and could trigger unsafe
-            // behaviour in subsequent processing.
-
-            // Particularly problematic noncharacters in 16-bit applications:
-
-            // 5.3.1  U+FFFE = ef bf be
-            roundtrip(true, "\xef\xbf\xbe");
-            // 5.3.2  U+FFFF = ef bf bf
-            roundtrip(true, "\xef\xbf\xbf");
-
-            // 5.3.3  U+FDD0 .. U+FDEF
-            roundtrip(true, "\xEF\xB7\x90");
-            roundtrip(true, "\xEF\xB7\x91");
-            roundtrip(true, "\xEF\xB7\x92");
-            roundtrip(true, "\xEF\xB7\x93");
-            roundtrip(true, "\xEF\xB7\x94");
-            roundtrip(true, "\xEF\xB7\x95");
-            roundtrip(true, "\xEF\xB7\x96");
-            roundtrip(true, "\xEF\xB7\x97");
-            roundtrip(true, "\xEF\xB7\x98");
-            roundtrip(true, "\xEF\xB7\x99");
-            roundtrip(true, "\xEF\xB7\x9A");
-            roundtrip(true, "\xEF\xB7\x9B");
-            roundtrip(true, "\xEF\xB7\x9C");
-            roundtrip(true, "\xEF\xB7\x9D");
-            roundtrip(true, "\xEF\xB7\x9E");
-            roundtrip(true, "\xEF\xB7\x9F");
-            roundtrip(true, "\xEF\xB7\xA0");
-            roundtrip(true, "\xEF\xB7\xA1");
-            roundtrip(true, "\xEF\xB7\xA2");
-            roundtrip(true, "\xEF\xB7\xA3");
-            roundtrip(true, "\xEF\xB7\xA4");
-            roundtrip(true, "\xEF\xB7\xA5");
-            roundtrip(true, "\xEF\xB7\xA6");
-            roundtrip(true, "\xEF\xB7\xA7");
-            roundtrip(true, "\xEF\xB7\xA8");
-            roundtrip(true, "\xEF\xB7\xA9");
-            roundtrip(true, "\xEF\xB7\xAA");
-            roundtrip(true, "\xEF\xB7\xAB");
-            roundtrip(true, "\xEF\xB7\xAC");
-            roundtrip(true, "\xEF\xB7\xAD");
-            roundtrip(true, "\xEF\xB7\xAE");
-            roundtrip(true, "\xEF\xB7\xAF");
-
-            // 5.3.4  U+nFFFE U+nFFFF (for n = 1..10)
-            roundtrip(true, "\xF0\x9F\xBF\xBF");
-            roundtrip(true, "\xF0\xAF\xBF\xBF");
-            roundtrip(true, "\xF0\xBF\xBF\xBF");
-            roundtrip(true, "\xF1\x8F\xBF\xBF");
-            roundtrip(true, "\xF1\x9F\xBF\xBF");
-            roundtrip(true, "\xF1\xAF\xBF\xBF");
-            roundtrip(true, "\xF1\xBF\xBF\xBF");
-            roundtrip(true, "\xF2\x8F\xBF\xBF");
-            roundtrip(true, "\xF2\x9F\xBF\xBF");
-            roundtrip(true, "\xF2\xAF\xBF\xBF");
-        }
-    }
-}

tests/src/unit-unicode2.cpp

@@ -1,612 +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
-
-#include "doctest_compatibility.h"
-
-// for some reason including this after the json header leads to linker errors with VS 2017...
-#include <locale>
-
-#include <nlohmann/json.hpp>
-using nlohmann::json;
-
-#include <fstream>
-#include <sstream>
-#include <iostream>
-#include <iomanip>
-#include "make_test_data_available.hpp"
-#include "test_utils.hpp"
-
-// this test suite uses static variables with non-trivial destructors
-DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
-DOCTEST_CLANG_SUPPRESS_WARNING("-Wexit-time-destructors")
-
-namespace
-{
-extern size_t calls;
-size_t calls = 0;
-
-void check_utf8dump(bool success_expected, int byte1, int byte2, int byte3, int byte4);
-
-void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3 = -1, int byte4 = -1)
-{
-    static std::string json_string;
-    json_string.clear();
-
-    CAPTURE(byte1)
-    CAPTURE(byte2)
-    CAPTURE(byte3)
-    CAPTURE(byte4)
-
-    json_string += std::string(1, static_cast<char>(byte1));
-
-    if (byte2 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte2));
-    }
-
-    if (byte3 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte3));
-    }
-
-    if (byte4 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte4));
-    }
-
-    CAPTURE(json_string)
-
-    // store the string in a JSON value
-    static json j;
-    static json j2;
-    j = json_string;
-    j2 = "abc" + json_string + "xyz";
-
-    static std::string s_ignored;
-    static std::string s_ignored2;
-    static std::string s_ignored_ascii;
-    static std::string s_ignored2_ascii;
-    static std::string s_replaced;
-    static std::string s_replaced2;
-    static std::string s_replaced_ascii;
-    static std::string s_replaced2_ascii;
-
-    // dumping with ignore/replace must not throw in any case
-    s_ignored = j.dump(-1, ' ', false, json::error_handler_t::ignore);
-    s_ignored2 = j2.dump(-1, ' ', false, json::error_handler_t::ignore);
-    s_ignored_ascii = j.dump(-1, ' ', true, json::error_handler_t::ignore);
-    s_ignored2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::ignore);
-    s_replaced = j.dump(-1, ' ', false, json::error_handler_t::replace);
-    s_replaced2 = j2.dump(-1, ' ', false, json::error_handler_t::replace);
-    s_replaced_ascii = j.dump(-1, ' ', true, json::error_handler_t::replace);
-    s_replaced2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::replace);
-
-    if (success_expected)
-    {
-        static std::string s_strict;
-        // strict mode must not throw if success is expected
-        s_strict = j.dump();
-        // all dumps should agree on the string
-        CHECK(s_strict == s_ignored);
-        CHECK(s_strict == s_replaced);
-    }
-    else
-    {
-        // strict mode must throw if success is not expected
-        // dump() is nodiscard; the exception is thrown by dump() itself before it would return
-        CHECK_THROWS_AS(utils::ignore_return_value(j.dump()), json::type_error&);
-        // ignore and replace must create different dumps
-        CHECK(s_ignored != s_replaced);
-
-        // check that replace string contains a replacement character
-        CHECK(s_replaced.find("\xEF\xBF\xBD") != std::string::npos);
-    }
-
-    // check that prefix and suffix are preserved
-    CHECK(s_ignored2.substr(1, 3) == "abc");
-    CHECK(s_ignored2.substr(s_ignored2.size() - 4, 3) == "xyz");
-    CHECK(s_ignored2_ascii.substr(1, 3) == "abc");
-    CHECK(s_ignored2_ascii.substr(s_ignored2_ascii.size() - 4, 3) == "xyz");
-    CHECK(s_replaced2.substr(1, 3) == "abc");
-    CHECK(s_replaced2.substr(s_replaced2.size() - 4, 3) == "xyz");
-    CHECK(s_replaced2_ascii.substr(1, 3) == "abc");
-    CHECK(s_replaced2_ascii.substr(s_replaced2_ascii.size() - 4, 3) == "xyz");
-}
-
-void check_utf8string(bool success_expected, int byte1, int byte2, int byte3, int byte4);
-
-// create and check a JSON string with up to four UTF-8 bytes
-void check_utf8string(bool success_expected, int byte1, int byte2 = -1, int byte3 = -1, int byte4 = -1)
-{
-    if (++calls % 100000 == 0)
-    {
-        std::cout << calls << " of 455355 UTF-8 strings checked" << std::endl; // NOLINT(performance-avoid-endl)
-    }
-
-    static std::string json_string;
-    json_string = "\"";
-
-    CAPTURE(byte1)
-    json_string += std::string(1, static_cast<char>(byte1));
-
-    if (byte2 != -1)
-    {
-        CAPTURE(byte2)
-        json_string += std::string(1, static_cast<char>(byte2));
-    }
-
-    if (byte3 != -1)
-    {
-        CAPTURE(byte3)
-        json_string += std::string(1, static_cast<char>(byte3));
-    }
-
-    if (byte4 != -1)
-    {
-        CAPTURE(byte4)
-        json_string += std::string(1, static_cast<char>(byte4));
-    }
-
-    json_string += "\"";
-
-    CAPTURE(json_string)
-
-    json _;
-    if (success_expected)
-    {
-        CHECK_NOTHROW(_ = json::parse(json_string));
-    }
-    else
-    {
-        CHECK_THROWS_AS(_ = json::parse(json_string), json::parse_error&);
-    }
-}
-} // namespace
-
-TEST_CASE("Unicode (2/5)" * doctest::skip())
-{
-    SECTION("RFC 3629")
-    {
-        /*
-        RFC 3629 describes in Sect. 4 the syntax of UTF-8 byte sequences as
-        follows:
-
-            A UTF-8 string is a sequence of octets representing a sequence of UCS
-            characters.  An octet sequence is valid UTF-8 only if it matches the
-            following syntax, which is derived from the rules for encoding UTF-8
-            and is expressed in the ABNF of [RFC2234].
-
-            UTF8-octets = *( UTF8-char )
-            UTF8-char   = UTF8-1 / UTF8-2 / UTF8-3 / UTF8-4
-            UTF8-1      = %x00-7F
-            UTF8-2      = %xC2-DF UTF8-tail
-            UTF8-3      = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) /
-                          %xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail )
-            UTF8-4      = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
-                          %xF4 %x80-8F 2( UTF8-tail )
-            UTF8-tail   = %x80-BF
-        */
-
-        SECTION("ill-formed first byte")
-        {
-            for (int byte1 = 0x80; byte1 <= 0xC1; ++byte1)
-            {
-                check_utf8string(false, byte1);
-                check_utf8dump(false, byte1);
-            }
-
-            for (int byte1 = 0xF5; byte1 <= 0xFF; ++byte1)
-            {
-                check_utf8string(false, byte1);
-                check_utf8dump(false, byte1);
-            }
-        }
-
-        SECTION("UTF8-1 (x00-x7F)")
-        {
-            SECTION("well-formed")
-            {
-                for (int byte1 = 0x00; byte1 <= 0x7F; ++byte1)
-                {
-                    // unescaped control characters are parse errors in JSON
-                    if (0x00 <= byte1 && byte1 <= 0x1F)
-                    {
-                        check_utf8string(false, byte1);
-                        continue;
-                    }
-
-                    // a single quote is a parse error in JSON
-                    if (byte1 == 0x22)
-                    {
-                        check_utf8string(false, byte1);
-                        continue;
-                    }
-
-                    // a single backslash is a parse error in JSON
-                    if (byte1 == 0x5C)
-                    {
-                        check_utf8string(false, byte1);
-                        continue;
-                    }
-
-                    // all other characters are OK
-                    check_utf8string(true, byte1);
-                    check_utf8dump(true, byte1);
-                }
-            }
-        }
-
-        SECTION("UTF8-2 (xC2-xDF UTF8-tail)")
-        {
-            SECTION("well-formed")
-            {
-                for (int byte1 = 0xC2; byte1 <= 0xDF; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        check_utf8string(true, byte1, byte2);
-                        check_utf8dump(true, byte1, byte2);
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing second byte")
-            {
-                for (int byte1 = 0xC2; byte1 <= 0xDF; ++byte1)
-                {
-                    check_utf8string(false, byte1);
-                    check_utf8dump(false, byte1);
-                }
-            }
-
-            SECTION("ill-formed: wrong second byte")
-            {
-                for (int byte1 = 0xC2; byte1 <= 0xDF; ++byte1)
-                {
-                    for (int byte2 = 0x00; byte2 <= 0xFF; ++byte2)
-                    {
-                        // skip correct second byte
-                        if (0x80 <= byte2 && byte2 <= 0xBF)
-                        {
-                            continue;
-                        }
-
-                        check_utf8string(false, byte1, byte2);
-                        check_utf8dump(false, byte1, byte2);
-                    }
-                }
-            }
-        }
-
-        SECTION("UTF8-3 (xE0 xA0-BF UTF8-tail)")
-        {
-            SECTION("well-formed")
-            {
-                for (int byte1 = 0xE0; byte1 <= 0xE0; ++byte1)
-                {
-                    for (int byte2 = 0xA0; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(true, byte1, byte2, byte3);
-                            check_utf8dump(true, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing second byte")
-            {
-                for (int byte1 = 0xE0; byte1 <= 0xE0; ++byte1)
-                {
-                    check_utf8string(false, byte1);
-                    check_utf8dump(false, byte1);
-                }
-            }
-
-            SECTION("ill-formed: missing third byte")
-            {
-                for (int byte1 = 0xE0; byte1 <= 0xE0; ++byte1)
-                {
-                    for (int byte2 = 0xA0; byte2 <= 0xBF; ++byte2)
-                    {
-                        check_utf8string(false, byte1, byte2);
-                        check_utf8dump(false, byte1, byte2);
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong second byte")
-            {
-                for (int byte1 = 0xE0; byte1 <= 0xE0; ++byte1)
-                {
-                    for (int byte2 = 0x00; byte2 <= 0xFF; ++byte2)
-                    {
-                        // skip correct second byte
-                        if (0xA0 <= byte2 && byte2 <= 0xBF)
-                        {
-                            continue;
-                        }
-
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong third byte")
-            {
-                for (int byte1 = 0xE0; byte1 <= 0xE0; ++byte1)
-                {
-                    for (int byte2 = 0xA0; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x00; byte3 <= 0xFF; ++byte3)
-                        {
-                            // skip correct third byte
-                            if (0x80 <= byte3 && byte3 <= 0xBF)
-                            {
-                                continue;
-                            }
-
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-        }
-
-        SECTION("UTF8-3 (xE1-xEC UTF8-tail UTF8-tail)")
-        {
-            SECTION("well-formed")
-            {
-                for (int byte1 = 0xE1; byte1 <= 0xEC; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(true, byte1, byte2, byte3);
-                            check_utf8dump(true, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing second byte")
-            {
-                for (int byte1 = 0xE1; byte1 <= 0xEC; ++byte1)
-                {
-                    check_utf8string(false, byte1);
-                    check_utf8dump(false, byte1);
-                }
-            }
-
-            SECTION("ill-formed: missing third byte")
-            {
-                for (int byte1 = 0xE1; byte1 <= 0xEC; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        check_utf8string(false, byte1, byte2);
-                        check_utf8dump(false, byte1, byte2);
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong second byte")
-            {
-                for (int byte1 = 0xE1; byte1 <= 0xEC; ++byte1)
-                {
-                    for (int byte2 = 0x00; byte2 <= 0xFF; ++byte2)
-                    {
-                        // skip correct second byte
-                        if (0x80 <= byte2 && byte2 <= 0xBF)
-                        {
-                            continue;
-                        }
-
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong third byte")
-            {
-                for (int byte1 = 0xE1; byte1 <= 0xEC; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x00; byte3 <= 0xFF; ++byte3)
-                        {
-                            // skip correct third byte
-                            if (0x80 <= byte3 && byte3 <= 0xBF)
-                            {
-                                continue;
-                            }
-
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-        }
-
-        SECTION("UTF8-3 (xED x80-9F UTF8-tail)")
-        {
-            SECTION("well-formed")
-            {
-                for (int byte1 = 0xED; byte1 <= 0xED; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0x9F; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(true, byte1, byte2, byte3);
-                            check_utf8dump(true, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing second byte")
-            {
-                for (int byte1 = 0xED; byte1 <= 0xED; ++byte1)
-                {
-                    check_utf8string(false, byte1);
-                    check_utf8dump(false, byte1);
-                }
-            }
-
-            SECTION("ill-formed: missing third byte")
-            {
-                for (int byte1 = 0xED; byte1 <= 0xED; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0x9F; ++byte2)
-                    {
-                        check_utf8string(false, byte1, byte2);
-                        check_utf8dump(false, byte1, byte2);
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong second byte")
-            {
-                for (int byte1 = 0xED; byte1 <= 0xED; ++byte1)
-                {
-                    for (int byte2 = 0x00; byte2 <= 0xFF; ++byte2)
-                    {
-                        // skip correct second byte
-                        if (0x80 <= byte2 && byte2 <= 0x9F)
-                        {
-                            continue;
-                        }
-
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong third byte")
-            {
-                for (int byte1 = 0xED; byte1 <= 0xED; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0x9F; ++byte2)
-                    {
-                        for (int byte3 = 0x00; byte3 <= 0xFF; ++byte3)
-                        {
-                            // skip correct third byte
-                            if (0x80 <= byte3 && byte3 <= 0xBF)
-                            {
-                                continue;
-                            }
-
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-        }
-
-        SECTION("UTF8-3 (xEE-xEF UTF8-tail UTF8-tail)")
-        {
-            SECTION("well-formed")
-            {
-                for (int byte1 = 0xEE; byte1 <= 0xEF; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(true, byte1, byte2, byte3);
-                            check_utf8dump(true, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing second byte")
-            {
-                for (int byte1 = 0xEE; byte1 <= 0xEF; ++byte1)
-                {
-                    check_utf8string(false, byte1);
-                    check_utf8dump(false, byte1);
-                }
-            }
-
-            SECTION("ill-formed: missing third byte")
-            {
-                for (int byte1 = 0xEE; byte1 <= 0xEF; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        check_utf8string(false, byte1, byte2);
-                        check_utf8dump(false, byte1, byte2);
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong second byte")
-            {
-                for (int byte1 = 0xEE; byte1 <= 0xEF; ++byte1)
-                {
-                    for (int byte2 = 0x00; byte2 <= 0xFF; ++byte2)
-                    {
-                        // skip correct second byte
-                        if (0x80 <= byte2 && byte2 <= 0xBF)
-                        {
-                            continue;
-                        }
-
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong third byte")
-            {
-                for (int byte1 = 0xEE; byte1 <= 0xEF; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x00; byte3 <= 0xFF; ++byte3)
-                        {
-                            // skip correct third byte
-                            if (0x80 <= byte3 && byte3 <= 0xBF)
-                            {
-                                continue;
-                            }
-
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-        }
-    }
-}
-
-DOCTEST_CLANG_SUPPRESS_WARNING_POP

tests/src/unit-unicode3.cpp

@@ -1,326 +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
-
-#include "doctest_compatibility.h"
-
-// for some reason including this after the json header leads to linker errors with VS 2017...
-#include <locale>
-
-#include <nlohmann/json.hpp>
-using nlohmann::json;
-
-#include <fstream>
-#include <sstream>
-#include <iostream>
-#include <iomanip>
-#include "make_test_data_available.hpp"
-#include "test_utils.hpp"
-
-// this test suite uses static variables with non-trivial destructors
-DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
-DOCTEST_CLANG_SUPPRESS_WARNING("-Wexit-time-destructors")
-
-namespace
-{
-extern size_t calls;
-size_t calls = 0;
-
-void check_utf8dump(bool success_expected, int byte1, int byte2, int byte3, int byte4);
-
-void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3 = -1, int byte4 = -1)
-{
-    static std::string json_string;
-    json_string.clear();
-
-    CAPTURE(byte1)
-    CAPTURE(byte2)
-    CAPTURE(byte3)
-    CAPTURE(byte4)
-
-    json_string += std::string(1, static_cast<char>(byte1));
-
-    if (byte2 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte2));
-    }
-
-    if (byte3 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte3));
-    }
-
-    if (byte4 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte4));
-    }
-
-    CAPTURE(json_string)
-
-    // store the string in a JSON value
-    static json j;
-    static json j2;
-    j = json_string;
-    j2 = "abc" + json_string + "xyz";
-
-    static std::string s_ignored;
-    static std::string s_ignored2;
-    static std::string s_ignored_ascii;
-    static std::string s_ignored2_ascii;
-    static std::string s_replaced;
-    static std::string s_replaced2;
-    static std::string s_replaced_ascii;
-    static std::string s_replaced2_ascii;
-
-    // dumping with ignore/replace must not throw in any case
-    s_ignored = j.dump(-1, ' ', false, json::error_handler_t::ignore);
-    s_ignored2 = j2.dump(-1, ' ', false, json::error_handler_t::ignore);
-    s_ignored_ascii = j.dump(-1, ' ', true, json::error_handler_t::ignore);
-    s_ignored2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::ignore);
-    s_replaced = j.dump(-1, ' ', false, json::error_handler_t::replace);
-    s_replaced2 = j2.dump(-1, ' ', false, json::error_handler_t::replace);
-    s_replaced_ascii = j.dump(-1, ' ', true, json::error_handler_t::replace);
-    s_replaced2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::replace);
-
-    if (success_expected)
-    {
-        static std::string s_strict;
-        // strict mode must not throw if success is expected
-        s_strict = j.dump();
-        // all dumps should agree on the string
-        CHECK(s_strict == s_ignored);
-        CHECK(s_strict == s_replaced);
-    }
-    else
-    {
-        // strict mode must throw if success is not expected
-        // dump() is nodiscard; the exception is thrown by dump() itself before it would return
-        CHECK_THROWS_AS(utils::ignore_return_value(j.dump()), json::type_error&);
-        // ignore and replace must create different dumps
-        CHECK(s_ignored != s_replaced);
-
-        // check that replace string contains a replacement character
-        CHECK(s_replaced.find("\xEF\xBF\xBD") != std::string::npos);
-    }
-
-    // check that prefix and suffix are preserved
-    CHECK(s_ignored2.substr(1, 3) == "abc");
-    CHECK(s_ignored2.substr(s_ignored2.size() - 4, 3) == "xyz");
-    CHECK(s_ignored2_ascii.substr(1, 3) == "abc");
-    CHECK(s_ignored2_ascii.substr(s_ignored2_ascii.size() - 4, 3) == "xyz");
-    CHECK(s_replaced2.substr(1, 3) == "abc");
-    CHECK(s_replaced2.substr(s_replaced2.size() - 4, 3) == "xyz");
-    CHECK(s_replaced2_ascii.substr(1, 3) == "abc");
-    CHECK(s_replaced2_ascii.substr(s_replaced2_ascii.size() - 4, 3) == "xyz");
-}
-
-void check_utf8string(bool success_expected, int byte1, int byte2, int byte3, int byte4);
-
-// create and check a JSON string with up to four UTF-8 bytes
-void check_utf8string(bool success_expected, int byte1, int byte2 = -1, int byte3 = -1, int byte4 = -1)
-{
-    if (++calls % 100000 == 0)
-    {
-        std::cout << calls << " of 1641521 UTF-8 strings checked" << std::endl; // NOLINT(performance-avoid-endl)
-    }
-
-    static std::string json_string;
-    json_string = "\"";
-
-    CAPTURE(byte1)
-    json_string += std::string(1, static_cast<char>(byte1));
-
-    if (byte2 != -1)
-    {
-        CAPTURE(byte2)
-        json_string += std::string(1, static_cast<char>(byte2));
-    }
-
-    if (byte3 != -1)
-    {
-        CAPTURE(byte3)
-        json_string += std::string(1, static_cast<char>(byte3));
-    }
-
-    if (byte4 != -1)
-    {
-        CAPTURE(byte4)
-        json_string += std::string(1, static_cast<char>(byte4));
-    }
-
-    json_string += "\"";
-
-    CAPTURE(json_string)
-
-    json _;
-    if (success_expected)
-    {
-        CHECK_NOTHROW(_ = json::parse(json_string));
-    }
-    else
-    {
-        CHECK_THROWS_AS(_ = json::parse(json_string), json::parse_error&);
-    }
-}
-} // namespace
-
-TEST_CASE("Unicode (3/5)" * doctest::skip())
-{
-    SECTION("RFC 3629")
-    {
-        /*
-        RFC 3629 describes in Sect. 4 the syntax of UTF-8 byte sequences as
-        follows:
-
-            A UTF-8 string is a sequence of octets representing a sequence of UCS
-            characters.  An octet sequence is valid UTF-8 only if it matches the
-            following syntax, which is derived from the rules for encoding UTF-8
-            and is expressed in the ABNF of [RFC2234].
-
-            UTF8-octets = *( UTF8-char )
-            UTF8-char   = UTF8-1 / UTF8-2 / UTF8-3 / UTF8-4
-            UTF8-1      = %x00-7F
-            UTF8-2      = %xC2-DF UTF8-tail
-            UTF8-3      = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) /
-                          %xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail )
-            UTF8-4      = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
-                          %xF4 %x80-8F 2( UTF8-tail )
-            UTF8-tail   = %x80-BF
-        */
-
-        SECTION("UTF8-4 (xF0 x90-BF UTF8-tail UTF8-tail)")
-        {
-            SECTION("well-formed")
-            {
-                for (int byte1 = 0xF0; byte1 <= 0xF0; ++byte1)
-                {
-                    for (int byte2 = 0x90; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            for (int byte4 = 0x80; byte4 <= 0xBF; ++byte4)
-                            {
-                                check_utf8string(true, byte1, byte2, byte3, byte4);
-                                check_utf8dump(true, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing second byte")
-            {
-                for (int byte1 = 0xF0; byte1 <= 0xF0; ++byte1)
-                {
-                    check_utf8string(false, byte1);
-                    check_utf8dump(false, byte1);
-                }
-            }
-
-            SECTION("ill-formed: missing third byte")
-            {
-                for (int byte1 = 0xF0; byte1 <= 0xF0; ++byte1)
-                {
-                    for (int byte2 = 0x90; byte2 <= 0xBF; ++byte2)
-                    {
-                        check_utf8string(false, byte1, byte2);
-                        check_utf8dump(false, byte1, byte2);
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing fourth byte")
-            {
-                for (int byte1 = 0xF0; byte1 <= 0xF0; ++byte1)
-                {
-                    for (int byte2 = 0x90; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong second byte")
-            {
-                for (int byte1 = 0xF0; byte1 <= 0xF0; ++byte1)
-                {
-                    for (int byte2 = 0x00; byte2 <= 0xFF; ++byte2)
-                    {
-                        // skip correct second byte
-                        if (0x90 <= byte2 && byte2 <= 0xBF)
-                        {
-                            continue;
-                        }
-
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            for (int byte4 = 0x80; byte4 <= 0xBF; ++byte4)
-                            {
-                                check_utf8string(false, byte1, byte2, byte3, byte4);
-                                check_utf8dump(false, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong third byte")
-            {
-                for (int byte1 = 0xF0; byte1 <= 0xF0; ++byte1)
-                {
-                    for (int byte2 = 0x90; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x00; byte3 <= 0xFF; ++byte3)
-                        {
-                            // skip correct third byte
-                            if (0x80 <= byte3 && byte3 <= 0xBF)
-                            {
-                                continue;
-                            }
-
-                            for (int byte4 = 0x80; byte4 <= 0xBF; ++byte4)
-                            {
-                                check_utf8string(false, byte1, byte2, byte3, byte4);
-                                check_utf8dump(false, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong fourth byte")
-            {
-                for (int byte1 = 0xF0; byte1 <= 0xF0; ++byte1)
-                {
-                    for (int byte2 = 0x90; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            for (int byte4 = 0x00; byte4 <= 0xFF; ++byte4)
-                            {
-                                // skip correct fourth byte
-                                if (0x80 <= byte4 && byte4 <= 0xBF)
-                                {
-                                    continue;
-                                }
-
-                                check_utf8string(false, byte1, byte2, byte3, byte4);
-                                check_utf8dump(false, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-        }
-    }
-}
-
-DOCTEST_CLANG_SUPPRESS_WARNING_POP

tests/src/unit-unicode4.cpp

@@ -1,326 +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
-
-#include "doctest_compatibility.h"
-
-// for some reason including this after the json header leads to linker errors with VS 2017...
-#include <locale>
-
-#include <nlohmann/json.hpp>
-using nlohmann::json;
-
-#include <fstream>
-#include <sstream>
-#include <iostream>
-#include <iomanip>
-#include "make_test_data_available.hpp"
-#include "test_utils.hpp"
-
-// this test suite uses static variables with non-trivial destructors
-DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
-DOCTEST_CLANG_SUPPRESS_WARNING("-Wexit-time-destructors")
-
-namespace
-{
-extern size_t calls;
-size_t calls = 0;
-
-void check_utf8dump(bool success_expected, int byte1, int byte2, int byte3, int byte4);
-
-void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3 = -1, int byte4 = -1)
-{
-    static std::string json_string;
-    json_string.clear();
-
-    CAPTURE(byte1)
-    CAPTURE(byte2)
-    CAPTURE(byte3)
-    CAPTURE(byte4)
-
-    json_string += std::string(1, static_cast<char>(byte1));
-
-    if (byte2 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte2));
-    }
-
-    if (byte3 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte3));
-    }
-
-    if (byte4 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte4));
-    }
-
-    CAPTURE(json_string)
-
-    // store the string in a JSON value
-    static json j;
-    static json j2;
-    j = json_string;
-    j2 = "abc" + json_string + "xyz";
-
-    static std::string s_ignored;
-    static std::string s_ignored2;
-    static std::string s_ignored_ascii;
-    static std::string s_ignored2_ascii;
-    static std::string s_replaced;
-    static std::string s_replaced2;
-    static std::string s_replaced_ascii;
-    static std::string s_replaced2_ascii;
-
-    // dumping with ignore/replace must not throw in any case
-    s_ignored = j.dump(-1, ' ', false, json::error_handler_t::ignore);
-    s_ignored2 = j2.dump(-1, ' ', false, json::error_handler_t::ignore);
-    s_ignored_ascii = j.dump(-1, ' ', true, json::error_handler_t::ignore);
-    s_ignored2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::ignore);
-    s_replaced = j.dump(-1, ' ', false, json::error_handler_t::replace);
-    s_replaced2 = j2.dump(-1, ' ', false, json::error_handler_t::replace);
-    s_replaced_ascii = j.dump(-1, ' ', true, json::error_handler_t::replace);
-    s_replaced2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::replace);
-
-    if (success_expected)
-    {
-        static std::string s_strict;
-        // strict mode must not throw if success is expected
-        s_strict = j.dump();
-        // all dumps should agree on the string
-        CHECK(s_strict == s_ignored);
-        CHECK(s_strict == s_replaced);
-    }
-    else
-    {
-        // strict mode must throw if success is not expected
-        // dump() is nodiscard; the exception is thrown by dump() itself before it would return
-        CHECK_THROWS_AS(utils::ignore_return_value(j.dump()), json::type_error&);
-        // ignore and replace must create different dumps
-        CHECK(s_ignored != s_replaced);
-
-        // check that replace string contains a replacement character
-        CHECK(s_replaced.find("\xEF\xBF\xBD") != std::string::npos);
-    }
-
-    // check that prefix and suffix are preserved
-    CHECK(s_ignored2.substr(1, 3) == "abc");
-    CHECK(s_ignored2.substr(s_ignored2.size() - 4, 3) == "xyz");
-    CHECK(s_ignored2_ascii.substr(1, 3) == "abc");
-    CHECK(s_ignored2_ascii.substr(s_ignored2_ascii.size() - 4, 3) == "xyz");
-    CHECK(s_replaced2.substr(1, 3) == "abc");
-    CHECK(s_replaced2.substr(s_replaced2.size() - 4, 3) == "xyz");
-    CHECK(s_replaced2_ascii.substr(1, 3) == "abc");
-    CHECK(s_replaced2_ascii.substr(s_replaced2_ascii.size() - 4, 3) == "xyz");
-}
-
-void check_utf8string(bool success_expected, int byte1, int byte2, int byte3, int byte4);
-
-// create and check a JSON string with up to four UTF-8 bytes
-void check_utf8string(bool success_expected, int byte1, int byte2 = -1, int byte3 = -1, int byte4 = -1)
-{
-    if (++calls % 100000 == 0)
-    {
-        std::cout << calls << " of 5517507 UTF-8 strings checked" << std::endl; // NOLINT(performance-avoid-endl)
-    }
-
-    static std::string json_string;
-    json_string = "\"";
-
-    CAPTURE(byte1)
-    json_string += std::string(1, static_cast<char>(byte1));
-
-    if (byte2 != -1)
-    {
-        CAPTURE(byte2)
-        json_string += std::string(1, static_cast<char>(byte2));
-    }
-
-    if (byte3 != -1)
-    {
-        CAPTURE(byte3)
-        json_string += std::string(1, static_cast<char>(byte3));
-    }
-
-    if (byte4 != -1)
-    {
-        CAPTURE(byte4)
-        json_string += std::string(1, static_cast<char>(byte4));
-    }
-
-    json_string += "\"";
-
-    CAPTURE(json_string)
-
-    json _;
-    if (success_expected)
-    {
-        CHECK_NOTHROW(_ = json::parse(json_string));
-    }
-    else
-    {
-        CHECK_THROWS_AS(_ = json::parse(json_string), json::parse_error&);
-    }
-}
-} // namespace
-
-TEST_CASE("Unicode (4/5)" * doctest::skip())
-{
-    SECTION("RFC 3629")
-    {
-        /*
-        RFC 3629 describes in Sect. 4 the syntax of UTF-8 byte sequences as
-        follows:
-
-            A UTF-8 string is a sequence of octets representing a sequence of UCS
-            characters.  An octet sequence is valid UTF-8 only if it matches the
-            following syntax, which is derived from the rules for encoding UTF-8
-            and is expressed in the ABNF of [RFC2234].
-
-            UTF8-octets = *( UTF8-char )
-            UTF8-char   = UTF8-1 / UTF8-2 / UTF8-3 / UTF8-4
-            UTF8-1      = %x00-7F
-            UTF8-2      = %xC2-DF UTF8-tail
-            UTF8-3      = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) /
-                          %xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail )
-            UTF8-4      = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
-                          %xF4 %x80-8F 2( UTF8-tail )
-            UTF8-tail   = %x80-BF
-        */
-
-        SECTION("UTF8-4 (xF1-F3 UTF8-tail UTF8-tail UTF8-tail)")
-        {
-            SECTION("well-formed")
-            {
-                for (int byte1 = 0xF1; byte1 <= 0xF3; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            for (int byte4 = 0x80; byte4 <= 0xBF; ++byte4)
-                            {
-                                check_utf8string(true, byte1, byte2, byte3, byte4);
-                                check_utf8dump(true, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing second byte")
-            {
-                for (int byte1 = 0xF1; byte1 <= 0xF3; ++byte1)
-                {
-                    check_utf8string(false, byte1);
-                    check_utf8dump(false, byte1);
-                }
-            }
-
-            SECTION("ill-formed: missing third byte")
-            {
-                for (int byte1 = 0xF1; byte1 <= 0xF3; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        check_utf8string(false, byte1, byte2);
-                        check_utf8dump(false, byte1, byte2);
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing fourth byte")
-            {
-                for (int byte1 = 0xF1; byte1 <= 0xF3; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong second byte")
-            {
-                for (int byte1 = 0xF1; byte1 <= 0xF3; ++byte1)
-                {
-                    for (int byte2 = 0x00; byte2 <= 0xFF; ++byte2)
-                    {
-                        // skip correct second byte
-                        if (0x80 <= byte2 && byte2 <= 0xBF)
-                        {
-                            continue;
-                        }
-
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            for (int byte4 = 0x80; byte4 <= 0xBF; ++byte4)
-                            {
-                                check_utf8string(false, byte1, byte2, byte3, byte4);
-                                check_utf8dump(false, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong third byte")
-            {
-                for (int byte1 = 0xF1; byte1 <= 0xF3; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x00; byte3 <= 0xFF; ++byte3)
-                        {
-                            // skip correct third byte
-                            if (0x80 <= byte3 && byte3 <= 0xBF)
-                            {
-                                continue;
-                            }
-
-                            for (int byte4 = 0x80; byte4 <= 0xBF; ++byte4)
-                            {
-                                check_utf8string(false, byte1, byte2, byte3, byte4);
-                                check_utf8dump(false, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong fourth byte")
-            {
-                for (int byte1 = 0xF1; byte1 <= 0xF3; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0xBF; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            for (int byte4 = 0x00; byte4 <= 0xFF; ++byte4)
-                            {
-                                // skip correct fourth byte
-                                if (0x80 <= byte4 && byte4 <= 0xBF)
-                                {
-                                    continue;
-                                }
-
-                                check_utf8string(false, byte1, byte2, byte3, byte4);
-                                check_utf8dump(false, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-        }
-    }
-}
-
-DOCTEST_CLANG_SUPPRESS_WARNING_POP

tests/src/unit-unicode5.cpp

@@ -1,326 +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
-
-#include "doctest_compatibility.h"
-
-// for some reason including this after the json header leads to linker errors with VS 2017...
-#include <locale>
-
-#include <nlohmann/json.hpp>
-using nlohmann::json;
-
-#include <fstream>
-#include <sstream>
-#include <iostream>
-#include <iomanip>
-#include "make_test_data_available.hpp"
-#include "test_utils.hpp"
-
-// this test suite uses static variables with non-trivial destructors
-DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
-DOCTEST_CLANG_SUPPRESS_WARNING("-Wexit-time-destructors")
-
-namespace
-{
-extern size_t calls;
-size_t calls = 0;
-
-void check_utf8dump(bool success_expected, int byte1, int byte2, int byte3, int byte4);
-
-void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3 = -1, int byte4 = -1)
-{
-    static std::string json_string;
-    json_string.clear();
-
-    CAPTURE(byte1)
-    CAPTURE(byte2)
-    CAPTURE(byte3)
-    CAPTURE(byte4)
-
-    json_string += std::string(1, static_cast<char>(byte1));
-
-    if (byte2 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte2));
-    }
-
-    if (byte3 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte3));
-    }
-
-    if (byte4 != -1)
-    {
-        json_string += std::string(1, static_cast<char>(byte4));
-    }
-
-    CAPTURE(json_string)
-
-    // store the string in a JSON value
-    static json j;
-    static json j2;
-    j = json_string;
-    j2 = "abc" + json_string + "xyz";
-
-    static std::string s_ignored;
-    static std::string s_ignored2;
-    static std::string s_ignored_ascii;
-    static std::string s_ignored2_ascii;
-    static std::string s_replaced;
-    static std::string s_replaced2;
-    static std::string s_replaced_ascii;
-    static std::string s_replaced2_ascii;
-
-    // dumping with ignore/replace must not throw in any case
-    s_ignored = j.dump(-1, ' ', false, json::error_handler_t::ignore);
-    s_ignored2 = j2.dump(-1, ' ', false, json::error_handler_t::ignore);
-    s_ignored_ascii = j.dump(-1, ' ', true, json::error_handler_t::ignore);
-    s_ignored2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::ignore);
-    s_replaced = j.dump(-1, ' ', false, json::error_handler_t::replace);
-    s_replaced2 = j2.dump(-1, ' ', false, json::error_handler_t::replace);
-    s_replaced_ascii = j.dump(-1, ' ', true, json::error_handler_t::replace);
-    s_replaced2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::replace);
-
-    if (success_expected)
-    {
-        static std::string s_strict;
-        // strict mode must not throw if success is expected
-        s_strict = j.dump();
-        // all dumps should agree on the string
-        CHECK(s_strict == s_ignored);
-        CHECK(s_strict == s_replaced);
-    }
-    else
-    {
-        // strict mode must throw if success is not expected
-        // dump() is nodiscard; the exception is thrown by dump() itself before it would return
-        CHECK_THROWS_AS(utils::ignore_return_value(j.dump()), json::type_error&);
-        // ignore and replace must create different dumps
-        CHECK(s_ignored != s_replaced);
-
-        // check that replace string contains a replacement character
-        CHECK(s_replaced.find("\xEF\xBF\xBD") != std::string::npos);
-    }
-
-    // check that prefix and suffix are preserved
-    CHECK(s_ignored2.substr(1, 3) == "abc");
-    CHECK(s_ignored2.substr(s_ignored2.size() - 4, 3) == "xyz");
-    CHECK(s_ignored2_ascii.substr(1, 3) == "abc");
-    CHECK(s_ignored2_ascii.substr(s_ignored2_ascii.size() - 4, 3) == "xyz");
-    CHECK(s_replaced2.substr(1, 3) == "abc");
-    CHECK(s_replaced2.substr(s_replaced2.size() - 4, 3) == "xyz");
-    CHECK(s_replaced2_ascii.substr(1, 3) == "abc");
-    CHECK(s_replaced2_ascii.substr(s_replaced2_ascii.size() - 4, 3) == "xyz");
-}
-
-void check_utf8string(bool success_expected, int byte1, int byte2, int byte3, int byte4);
-
-// create and check a JSON string with up to four UTF-8 bytes
-void check_utf8string(bool success_expected, int byte1, int byte2 = -1, int byte3 = -1, int byte4 = -1)
-{
-    if (++calls % 100000 == 0)
-    {
-        std::cout << calls << " of 1246225 UTF-8 strings checked" << std::endl; // NOLINT(performance-avoid-endl)
-    }
-
-    static std::string json_string;
-    json_string = "\"";
-
-    CAPTURE(byte1)
-    json_string += std::string(1, static_cast<char>(byte1));
-
-    if (byte2 != -1)
-    {
-        CAPTURE(byte2)
-        json_string += std::string(1, static_cast<char>(byte2));
-    }
-
-    if (byte3 != -1)
-    {
-        CAPTURE(byte3)
-        json_string += std::string(1, static_cast<char>(byte3));
-    }
-
-    if (byte4 != -1)
-    {
-        CAPTURE(byte4)
-        json_string += std::string(1, static_cast<char>(byte4));
-    }
-
-    json_string += "\"";
-
-    CAPTURE(json_string)
-
-    json _;
-    if (success_expected)
-    {
-        CHECK_NOTHROW(_ = json::parse(json_string));
-    }
-    else
-    {
-        CHECK_THROWS_AS(_ = json::parse(json_string), json::parse_error&);
-    }
-}
-} // namespace
-
-TEST_CASE("Unicode (5/5)" * doctest::skip())
-{
-    SECTION("RFC 3629")
-    {
-        /*
-        RFC 3629 describes in Sect. 4 the syntax of UTF-8 byte sequences as
-        follows:
-
-            A UTF-8 string is a sequence of octets representing a sequence of UCS
-            characters.  An octet sequence is valid UTF-8 only if it matches the
-            following syntax, which is derived from the rules for encoding UTF-8
-            and is expressed in the ABNF of [RFC2234].
-
-            UTF8-octets = *( UTF8-char )
-            UTF8-char   = UTF8-1 / UTF8-2 / UTF8-3 / UTF8-4
-            UTF8-1      = %x00-7F
-            UTF8-2      = %xC2-DF UTF8-tail
-            UTF8-3      = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) /
-                          %xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail )
-            UTF8-4      = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
-                          %xF4 %x80-8F 2( UTF8-tail )
-            UTF8-tail   = %x80-BF
-        */
-
-        SECTION("UTF8-4 (xF4 x80-8F UTF8-tail UTF8-tail)")
-        {
-            SECTION("well-formed")
-            {
-                for (int byte1 = 0xF4; byte1 <= 0xF4; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0x8F; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            for (int byte4 = 0x80; byte4 <= 0xBF; ++byte4)
-                            {
-                                check_utf8string(true, byte1, byte2, byte3, byte4);
-                                check_utf8dump(true, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing second byte")
-            {
-                for (int byte1 = 0xF4; byte1 <= 0xF4; ++byte1)
-                {
-                    check_utf8string(false, byte1);
-                    check_utf8dump(false, byte1);
-                }
-            }
-
-            SECTION("ill-formed: missing third byte")
-            {
-                for (int byte1 = 0xF4; byte1 <= 0xF4; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0x8F; ++byte2)
-                    {
-                        check_utf8string(false, byte1, byte2);
-                        check_utf8dump(false, byte1, byte2);
-                    }
-                }
-            }
-
-            SECTION("ill-formed: missing fourth byte")
-            {
-                for (int byte1 = 0xF4; byte1 <= 0xF4; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0x8F; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            check_utf8string(false, byte1, byte2, byte3);
-                            check_utf8dump(false, byte1, byte2, byte3);
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong second byte")
-            {
-                for (int byte1 = 0xF4; byte1 <= 0xF4; ++byte1)
-                {
-                    for (int byte2 = 0x00; byte2 <= 0xFF; ++byte2)
-                    {
-                        // skip correct second byte
-                        if (0x80 <= byte2 && byte2 <= 0x8F)
-                        {
-                            continue;
-                        }
-
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            for (int byte4 = 0x80; byte4 <= 0xBF; ++byte4)
-                            {
-                                check_utf8string(false, byte1, byte2, byte3, byte4);
-                                check_utf8dump(false, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong third byte")
-            {
-                for (int byte1 = 0xF4; byte1 <= 0xF4; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0x8F; ++byte2)
-                    {
-                        for (int byte3 = 0x00; byte3 <= 0xFF; ++byte3)
-                        {
-                            // skip correct third byte
-                            if (0x80 <= byte3 && byte3 <= 0xBF)
-                            {
-                                continue;
-                            }
-
-                            for (int byte4 = 0x80; byte4 <= 0xBF; ++byte4)
-                            {
-                                check_utf8string(false, byte1, byte2, byte3, byte4);
-                                check_utf8dump(false, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-
-            SECTION("ill-formed: wrong fourth byte")
-            {
-                for (int byte1 = 0xF4; byte1 <= 0xF4; ++byte1)
-                {
-                    for (int byte2 = 0x80; byte2 <= 0x8F; ++byte2)
-                    {
-                        for (int byte3 = 0x80; byte3 <= 0xBF; ++byte3)
-                        {
-                            for (int byte4 = 0x00; byte4 <= 0xFF; ++byte4)
-                            {
-                                // skip correct fourth byte
-                                if (0x80 <= byte4 && byte4 <= 0xBF)
-                                {
-                                    continue;
-                                }
-
-                                check_utf8string(false, byte1, byte2, byte3, byte4);
-                                check_utf8dump(false, byte1, byte2, byte3, byte4);
-                            }
-                        }
-                    }
-                }
-            }
-        }
-    }
-}
-
-DOCTEST_CLANG_SUPPRESS_WARNING_POP