Merge remote-tracking branch 'origin/develop' into fix/develop-ci-after-merges

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

BUILD.bazel

@@ -57,6 +57,7 @@ cc_library(
         "include/nlohmann/detail/meta/type_traits.hpp",
         "include/nlohmann/detail/meta/void_t.hpp",
         "include/nlohmann/detail/output/binary_writer.hpp",
+        "include/nlohmann/detail/output/error_handler.hpp",
         "include/nlohmann/detail/output/output_adapters.hpp",
         "include/nlohmann/detail/output/serializer.hpp",
         "include/nlohmann/detail/recursion_depth_limit.hpp",

cmake/ci.cmake

@@ -596,8 +596,9 @@ foreach(SRC_FILE ${SRC_FILES})
     add_executable(single_${RELATIVE_SRC_FILE} EXCLUDE_FROM_ALL ${PROJECT_BINARY_DIR}/src_single/${RELATIVE_SRC_FILE}.cpp)
     target_include_directories(single_${RELATIVE_SRC_FILE} PRIVATE ${PROJECT_SOURCE_DIR}/include)
     target_compile_features(single_${RELATIVE_SRC_FILE} PRIVATE cxx_std_11)
-    if(RELATIVE_SRC_FILE STREQUAL "json")
-        # see below: report json.hpp's diagnostics without --error, so they do not fail the build
+    if(RELATIVE_SRC_FILE STREQUAL "json" OR RELATIVE_SRC_FILE STREQUAL "json_literals")
+        # see below: report the diagnostics of json.hpp and json_literals.hpp without --error, so they
+        # do not fail the build
         set_property(TARGET single_${RELATIVE_SRC_FILE} PROPERTY CXX_INCLUDE_WHAT_YOU_USE ${IWYU_TOOL} -Xiwyu --max_line_length=300)
     else()
         set_property(TARGET single_${RELATIVE_SRC_FILE} PROPERTY CXX_INCLUDE_WHAT_YOU_USE "${iwyu_path_and_options}")
@@ -611,7 +612,10 @@ foreach(SRC_FILE ${SRC_FILES})
     # reporting its diagnostics (informational, via CXX_INCLUDE_WHAT_YOU_USE above) but exclude it
     # from the hard gate below so a fresh IWYU/compiler combination does not fail this target on a
     # nondeterministic suggestion for a header that already re-exports everything on purpose.
-    if(NOT RELATIVE_SRC_FILE STREQUAL "json")
+    # json_literals.hpp and json.hpp include each other on purpose (json.hpp includes it at its end
+    # unless JSON_NO_AUTOMATIC_UDLS is defined), and IWYU, not following the cycle, suggests replacing
+    # json.hpp with json_fwd.hpp although the literals need the complete basic_json; exclude it, too.
+    if(NOT RELATIVE_SRC_FILE STREQUAL "json" AND NOT RELATIVE_SRC_FILE STREQUAL "json_literals")
         list(APPEND single_binaries_tus src_single/${RELATIVE_SRC_FILE}.cpp)
     endif()
 endforeach()

docs/docset/docSet.sql

@@ -242,6 +242,7 @@ INSERT INTO searchIndex(name, type, path) VALUES ('JSON_NO_THREAD_LOCAL', 'Macro
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_PRECISE_STREAM_POSITION', 'Macro', 'api/macros/json_precise_stream_position/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_SKIP_LIBRARY_VERSION_CHECK', 'Macro', 'api/macros/json_skip_library_version_check/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_SKIP_UNSUPPORTED_COMPILER_CHECK', 'Macro', 'api/macros/json_skip_unsupported_compiler_check/index.html');
+INSERT INTO searchIndex(name, type, path) VALUES ('JSON_STRICT_BINARY_UTF8', 'Macro', 'api/macros/json_strict_binary_utf8/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_STRICT_NUL_HANDLING', 'Macro', 'api/macros/json_strict_nul_handling/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_THROW_USER', 'Macro', 'api/macros/json_throw_user/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_TRY_USER', 'Macro', 'api/macros/json_throw_user/index.html');

docs/mkdocs/docs/api/macros/json_no_automatic_udls.md

@@ -43,9 +43,9 @@ By default, `#!cpp JSON_NO_AUTOMATIC_UDLS` is not defined, and `<nlohmann/json.h
 
     ```cpp
     // compiled with -DJSON_NO_AUTOMATIC_UDLS for the whole project
-    #include <nlohmann/json.hpp>
 
     // this file uses the literals, so it includes them explicitly
+    // (the header includes <nlohmann/json.hpp> itself)
     #include <nlohmann/json_literals.hpp>
 
     int main()
@@ -62,6 +62,7 @@ By default, `#!cpp JSON_NO_AUTOMATIC_UDLS` is not defined, and `<nlohmann/json.h
 - [`operator""_json`](../operator_literal_json.md)
 - [`operator""_json_pointer`](../operator_literal_json_pointer.md)
 - [`JSON_USE_GLOBAL_UDLS`](json_use_global_udls.md) - place user-defined string literals (UDLs) into the global namespace
+- [Compile times](../../integration/compile_times.md) - options to reduce compile times
 
 ## Version history
 

docs/mkdocs/docs/api/macros/json_strict_binary_utf8.md

@@ -54,7 +54,7 @@ The default value is `0` (disabled, the behavior of version 3.12.0 and earlier i
 
 ## Examples
 
-??? example "Default behavior (macro not defined)"
+??? example "Example: default behavior (macro not defined)"
 
     Without the macro, the bytes are written unchanged:
 
@@ -70,7 +70,7 @@ The default value is `0` (disabled, the behavior of version 3.12.0 and earlier i
     }
     ```
 
-??? example "Opt-in check (macro defined to 1)"
+??? example "Example: opt-in check (macro defined to 1)"
 
     With the macro, ill-formed UTF-8 is rejected:
 

docs/mkdocs/docs/api/macros/json_use_implicit_conversions.md

@@ -44,7 +44,7 @@ By default, implicit conversions are enabled.
 
 ## Examples
 
-??? example
+??? example "Example: implicit conversion"
 
     This is an example for an implicit conversion:
 
@@ -61,7 +61,7 @@ By default, implicit conversions are enabled.
     auto s = j.get<std::string>();
     ```
 
-??? example "Conversion between `basic_json` specializations"
+??? example "Example: conversion between `basic_json` specializations"
 
     A `basic_json` specialization with a different string type is also no longer converted implicitly when
     `JSON_USE_IMPLICIT_CONVERSIONS` is defined to `0`:

docs/mkdocs/docs/integration/compile_times.md

@@ -0,0 +1,149 @@
+# Compile times
+
+The library is header-only and makes heavy use of templates, so every translation unit that includes
+`<nlohmann/json.hpp>` pays for parsing the header and instantiating what it uses. This page lists the options to reduce
+that cost, ordered by how much they typically save.
+
+!!! info "Measurements"
+
+    The numbers below are medians of nine runs compiling a single translation unit with `-std=c++17 -c` against the
+    single-header version, with Apple clang and GCC 16 on macOS (Apple silicon). They show the order of magnitude to
+    expect; measure your own code before and after a change.
+
+## Include `json_fwd.hpp` in headers
+
+Header files that only need to *name* the `json` type — for function declarations, members held by pointer or
+reference, or friend declarations — can include `<nlohmann/json_fwd.hpp>` instead of `<nlohmann/json.hpp>`. It only
+forward-declares `basic_json`, `json`, `ordered_json`, `json_pointer`, and `adl_serializer`. The translation units that
+actually use the values then include `<nlohmann/json.hpp>`.
+
+```cpp title="person.hpp"
+#pragma once
+#include <nlohmann/json_fwd.hpp>
+
+struct person;
+void to_json(nlohmann::json& j, const person& p);
+void from_json(const nlohmann::json& j, person& p);
+```
+
+```cpp title="person.cpp"
+#include "person.hpp"
+#include <nlohmann/json.hpp>
+
+void to_json(nlohmann::json& j, const person& p) { /* ... */ }
+void from_json(const nlohmann::json& j, person& p) { /* ... */ }
+```
+
+| Compiler    | `json.hpp` (`-O0`) | `json_fwd.hpp` (`-O0`) | Change |
+|-------------|-------------------:|-----------------------:|-------:|
+| Apple clang |             704 ms |                 329 ms |   −53% |
+| GCC 16      |             779 ms |                 242 ms |   −69% |
+
+This is the most effective option, because it avoids the full header in every translation unit that includes
+*your* headers.
+
+## Opt out of the automatic user-defined string literals
+
+The user-defined string literals [`operator""_json`](../api/operator_literal_json.md) and
+[`operator""_json_pointer`](../api/operator_literal_json_pointer.md) are ordinary inline functions whose bodies call the
+parser. As `<nlohmann/json.hpp>` includes them by default, every translation unit instantiates the parser, even if it
+never parses anything itself.
+
+Define [`JSON_NO_AUTOMATIC_UDLS`](../api/macros/json_no_automatic_udls.md) for the whole project and include
+`<nlohmann/json_literals.hpp>` instead of `<nlohmann/json.hpp>` in the files that use the literals (it includes
+`<nlohmann/json.hpp>` itself):
+
+```cmake
+target_compile_definitions(my_target PRIVATE JSON_NO_AUTOMATIC_UDLS)
+```
+
+```cpp
+#include <nlohmann/json_literals.hpp> // only where "..."_json is used; includes <nlohmann/json.hpp>
+```
+
+The saving applies to translation units that do not parse JSON, for example ones that define types and their
+conversions or only pass `json` values around:
+
+| Compiler    | Translation unit | Default (`-O0` / `-O2`) | `JSON_NO_AUTOMATIC_UDLS` (`-O0` / `-O2`) | Change      |
+|-------------|------------------|------------------------:|-----------------------------------------:|------------:|
+| Apple clang | model            |         776 ms / 846 ms |                          629 ms / 692 ms | −19% / −18% |
+| GCC 16      | model            |       1022 ms / 1120 ms |                          882 ms / 965 ms | −14% / −14% |
+| Apple clang | parsing          |       992 ms / 1815 ms |                        1006 ms / 1823 ms |   +1% / 0% |
+| GCC 16      | parsing          |      2018 ms / 3420 ms |                        1990 ms / 3454 ms |   −1% / +1% |
+
+Translation units that include only the header save up to a third. Translation units that parse anyway instantiate
+the parser regardless and see no difference.
+
+## Instantiate `basic_json` once
+
+Each translation unit instantiates the member functions of `nlohmann::json` it uses. An explicit instantiation
+declaration tells the compiler that the non-template members are instantiated elsewhere, so it can skip them:
+
+```cpp title="json_instance.hpp"
+#pragma once
+#include <nlohmann/json.hpp>
+
+extern template class nlohmann::basic_json<>;
+```
+
+```cpp title="json_instance.cpp"
+#include "json_instance.hpp"
+
+template class nlohmann::basic_json<>;
+```
+
+Include `json_instance.hpp` instead of `<nlohmann/json.hpp>` and compile and link `json_instance.cpp` once.
+
+| Compiler    | Translation unit    | Default (`-O0` / `-O2`) | `extern template` (`-O0` / `-O2`) | Change      |
+|-------------|---------------------|------------------------:|----------------------------------:|------------:|
+| Apple clang | parsing             |        992 ms / 1815 ms |                  953 ms / 1625 ms |  −4% / −10% |
+| GCC 16      | parsing             |       2018 ms / 3420 ms |                 1522 ms / 2728 ms | −25% / −20% |
+| Apple clang | `json_instance.cpp` |                       — |                 2166 ms / 4660 ms |           — |
+| GCC 16      | `json_instance.cpp` |                       — |                5085 ms / 10616 ms |           — |
+
+Notes:
+
+- The saving grows with the number of translation units that use `json`, while the instantiation translation unit is
+  compiled only once (and is rarely recompiled, as it does not depend on your code).
+- Member function templates (such as `get<T>()`, `parse(InputType&&)`, or `value(key, default)`) are not covered by
+  the explicit instantiation and are still instantiated where they are used.
+- The declaration covers exactly `nlohmann::json`. Add the same lines for `nlohmann::ordered_json`
+  (`nlohmann::basic_json<nlohmann::ordered_map>`) or your own `basic_json` specializations if you use them.
+
+## Use C++20 modules
+
+With a toolchain that supports named modules, `import nlohmann.json;` compiles the library once into a module and
+avoids parsing the header in every translation unit. See [Modules](../features/modules.md) for requirements and known
+issues. Module support is experimental and currently depends heavily on the compiler version.
+
+## Use precompiled headers
+
+Build systems can precompile `<nlohmann/json.hpp>` together with other stable headers, for example with CMake's
+[`target_precompile_headers`](https://cmake.org/cmake/help/latest/command/target_precompile_headers.html):
+
+```cmake
+target_precompile_headers(my_target PRIVATE <nlohmann/json.hpp>)
+```
+
+This removes the cost of parsing the header, but not of instantiating templates in each translation unit, so it
+combines well with the options above.
+
+## Options without effect on compile times
+
+Some configuration macros change what the library declares, but do not measurably change compile times:
+
+| Macro                                                                  | Apple clang, model (`-O0` / `-O2`) | GCC 16, model (`-O0` / `-O2`) |
+|------------------------------------------------------------------------|-----------------------------------:|------------------------------:|
+| default                                                                |                    776 ms / 846 ms |             1022 ms / 1120 ms |
+| [`JSON_NO_IO`](../api/macros/json_no_io.md)                            |                    764 ms / 836 ms |             1022 ms / 1117 ms |
+| [`JSON_USE_GLOBAL_UDLS`](../api/macros/json_use_global_udls.md)`=0`    |                    763 ms / 852 ms |             1019 ms / 1106 ms |
+
+`JSON_USE_GLOBAL_UDLS` only controls *where* the literals are declared; to avoid their cost, use
+`JSON_NO_AUTOMATIC_UDLS` instead.
+
+## See also
+
+- [`JSON_NO_AUTOMATIC_UDLS`](../api/macros/json_no_automatic_udls.md) - do not include the user-defined string
+  literals automatically
+- [Modules](../features/modules.md) - C++20 module support
+- [Header only](index.md) - including the library

docs/mkdocs/docs/integration/index.md

@@ -45,7 +45,7 @@ Clang).
 
 You can further use file
 [`single_include/nlohmann/json_fwd.hpp`](https://github.com/nlohmann/json/blob/develop/single_include/nlohmann/json_fwd.hpp)
-for forward declarations, and file
+for forward declarations (see [Compile times](compile_times.md)), and file
 [`single_include/nlohmann/json_literals.hpp`](https://github.com/nlohmann/json/blob/develop/single_include/nlohmann/json_literals.hpp)
 for the user-defined string literals if you define
 [`JSON_NO_AUTOMATIC_UDLS`](../api/macros/json_no_automatic_udls.md).

docs/mkdocs/mkdocs.yml

@@ -108,6 +108,7 @@ nav:
       - integration/cmake.md
       - integration/package_managers.md
       - integration/pkg-config.md
+      - integration/compile_times.md
   - API Documentation:
       - basic_json:
           - 'Overview': api/basic_json/index.md

include/nlohmann/detail/input/binary_reader.hpp

@@ -110,15 +110,15 @@ class binary_reader
 
     @param[in] adapter  input adapter to read from
     @param[in] format   the binary format to parse
-    @param[in] error_handler  how to treat text strings and object keys that
+    @param[in] error_handler_  how to treat text strings and object keys that
                are not well-formed UTF-8; none of the supported formats
                requires a decoder to reject those, so the default is to
                @ref error_handler_t::keep them unchanged, as every binary
                reader did before this parameter existed
     */
     explicit binary_reader(InputAdapterType&& adapter, const input_format_t format = input_format_t::json,
-                           const error_handler_t error_handler = error_handler_t::keep) noexcept
-        : ia(std::move(adapter)), input_format(format), error_handler(error_handler)
+                           const error_handler_t error_handler_ = error_handler_t::keep) noexcept
+        : ia(std::move(adapter)), input_format(format), error_handler(error_handler_)
     {
         (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
     }

include/nlohmann/detail/json_pointer.hpp

@@ -322,6 +322,8 @@ class json_pointer
         typename BasicJsonType::size_type idx{};
         switch (parse_array_index<BasicJsonType>(s, idx))
         {
+            // the branches differ in their messages, not after JSON_THROW's expansion
+            // NOLINTNEXTLINE(bugprone-branch-clone)
             case array_index_status::leading_zero:
                 JSON_THROW(detail::parse_error::create(106, 0, detail::concat("array index '", s, "' must not begin with '0'"), nullptr));
             case array_index_status::not_a_number:
@@ -685,6 +687,8 @@ class json_pointer
                     typename BasicJsonType::size_type idx{};
                     switch (parse_array_index<BasicJsonType>(reference_token, idx))
                     {
+                        // the branches differ in their messages, not after JSON_THROW's expansion
+                        // NOLINTNEXTLINE(bugprone-branch-clone)
                         case array_index_status::leading_zero:
                             JSON_THROW(detail::parse_error::create(106, 0, detail::concat("array index '", reference_token, "' must not begin with '0'"), nullptr));
                         case array_index_status::not_a_number:

include/nlohmann/detail/output/binary_writer.hpp

@@ -2260,18 +2260,18 @@ class binary_writer
         switch (error_handler)
         {
             case error_handler_t::keep:
-                return s;
+                return s; // NOLINT(bugprone-return-const-ref-from-parameter): callers pass lvalues that outlive the call
 
             case error_handler_t::strict:
                 check_utf8(s, context);
-                return s;
+                return s; // NOLINT(bugprone-return-const-ref-from-parameter): callers pass lvalues that outlive the call
 
             case error_handler_t::replace:
             case error_handler_t::ignore:
             default:
                 if (is_valid_utf8(s))
                 {
-                    return s;
+                    return s; // NOLINT(bugprone-return-const-ref-from-parameter): callers pass lvalues that outlive the call
                 }
                 storage = sanitize_utf8(s, error_handler);
                 return storage;

include/nlohmann/detail/output/serializer.hpp

@@ -706,6 +706,11 @@ class serializer
     @a ensure_ascii is a template parameter here so that the branch on it is
     resolved once, outside the loop; see @ref dump_escaped.
     */
+#ifdef JSON_HEDLEY_MSVC_VERSION
+#pragma warning(push)
+    // EnsureAscii is a template parameter; C++11 has no if constexpr
+#pragma warning(disable : 4127) // conditional expression is constant
+#endif
     template<bool EnsureAscii>
     void dump_escaped_impl(const string_t& s)
     {
@@ -1055,6 +1060,9 @@ class serializer
             }
         }
     }
+#ifdef JSON_HEDLEY_MSVC_VERSION
+#pragma warning(pop)
+#endif
 
   private:
     /*!

include/nlohmann/json.hpp

@@ -1048,6 +1048,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
           never name it to call this constructor itself.
     */
     basic_json(copy_construct_tag /*unused*/, const basic_json& src)
+    noexcept(std::is_nothrow_copy_constructible<json_base_class_t>::value)
         : json_base_class_t(src)
 #if JSON_DIAGNOSTIC_POSITIONS
         , start_position(src.start_position)
@@ -1442,7 +1443,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     be destroyed.
     */
     template<typename BasicJsonType>
-    void convert_iteratively(const BasicJsonType& val)
+    void convert_iteratively(const BasicJsonType& val, std::true_type /*unused*/)
     {
         using other_const_iterator = typename BasicJsonType::const_iterator;
 
@@ -1536,21 +1537,38 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 
         if (JSON_HEDLEY_LIKELY(guard.okay()))
         {
-            // every element comes back to the converting constructor
-            if (val.is_object())
-            {
-                using other_object_t = typename BasicJsonType::object_t;
-                JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
-            }
-            else
-            {
-                using other_array_t = typename BasicJsonType::array_t;
-                JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
-            }
+            convert_by_serializers(val);
             return;
         }
 
-        convert_iteratively(val);
+        // the iterative conversion needs to construct this object type's keys
+        // from those of @a val; if it cannot, neither can the range constructor,
+        // and the serializers convert @a val some other way (see #3425)
+        convert_iteratively(val, std::is_constructible<typename object_t::key_type, const typename BasicJsonType::string_t&> {});
+    }
+
+    /// @brief convert the object or array @a val with the serializers; every
+    /// element comes back to the converting constructor
+    template<typename BasicJsonType>
+    void convert_by_serializers(const BasicJsonType& val)
+    {
+        if (val.is_object())
+        {
+            using other_object_t = typename BasicJsonType::object_t;
+            JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
+        }
+        else
+        {
+            using other_array_t = typename BasicJsonType::array_t;
+            JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
+        }
+    }
+
+    /// @brief convert @a val whose keys cannot be converted, see @ref convert_structured
+    template<typename BasicJsonType>
+    void convert_iteratively(const BasicJsonType& val, std::false_type /*unused*/)
+    {
+        convert_by_serializers(val);
     }
 
 
@@ -1624,15 +1642,15 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static compare_result compare_leaves(const_reference lhs, const_reference rhs, std::true_type /*ordered*/) noexcept
     {
         const std::partial_ordering order = lhs <=> rhs; // *NOPAD*
-        if (order == 0)
+        if (std::is_eq(order))
         {
             return compare_result::equal;
         }
-        if (order < 0)
+        if (std::is_lt(order))
         {
             return compare_result::less;
         }
-        if (order > 0)
+        if (std::is_gt(order))
         {
             return compare_result::greater;
         }
@@ -5058,7 +5076,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_le/
     template<typename ScalarType>
     requires std::is_scalar_v<ScalarType>
-    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept
+    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) <= rhs;
     }
@@ -5067,7 +5085,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ge/
     template<typename ScalarType>
     requires std::is_scalar_v<ScalarType>
-    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept
+    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) >= rhs;
     }

include/nlohmann/ordered_map.hpp

@@ -12,7 +12,7 @@
 #include <functional> // equal_to, less
 #include <initializer_list> // initializer_list
 #include <iterator> // input_iterator_tag, iterator_traits
-#include <memory> // allocator
+#include <memory> // allocator // IWYU pragma: keep
 #include <new> // for operator new (placement new)
 #include <stdexcept> // for out_of_range
 #include <tuple> // forward_as_tuple
@@ -78,7 +78,7 @@ private:
     /// @brief find the entry for @a key, for either constness of @a self
     /// @note the single place that performs the linear key search
     template<typename Self, typename KeyType>
-    static auto find_impl(Self& self, KeyType&& key) -> decltype(self.begin())
+    static auto find_impl(Self& self, const KeyType& key) -> decltype(self.begin())
     {
         for (auto it = self.begin(); it != self.end(); ++it)
         {

single_include/nlohmann/json.hpp

@@ -13696,15 +13696,15 @@ class binary_reader
 
     @param[in] adapter  input adapter to read from
     @param[in] format   the binary format to parse
-    @param[in] error_handler  how to treat text strings and object keys that
+    @param[in] error_handler_  how to treat text strings and object keys that
                are not well-formed UTF-8; none of the supported formats
                requires a decoder to reject those, so the default is to
                @ref error_handler_t::keep them unchanged, as every binary
                reader did before this parameter existed
     */
     explicit binary_reader(InputAdapterType&& adapter, const input_format_t format = input_format_t::json,
-                           const error_handler_t error_handler = error_handler_t::keep) noexcept
-        : ia(std::move(adapter)), input_format(format), error_handler(error_handler)
+                           const error_handler_t error_handler_ = error_handler_t::keep) noexcept
+        : ia(std::move(adapter)), input_format(format), error_handler(error_handler_)
     {
         (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
     }
@@ -19998,6 +19998,8 @@ class json_pointer
         typename BasicJsonType::size_type idx{};
         switch (parse_array_index<BasicJsonType>(s, idx))
         {
+            // the branches differ in their messages, not after JSON_THROW's expansion
+            // NOLINTNEXTLINE(bugprone-branch-clone)
             case array_index_status::leading_zero:
                 JSON_THROW(detail::parse_error::create(106, 0, detail::concat("array index '", s, "' must not begin with '0'"), nullptr));
             case array_index_status::not_a_number:
@@ -20361,6 +20363,8 @@ class json_pointer
                     typename BasicJsonType::size_type idx{};
                     switch (parse_array_index<BasicJsonType>(reference_token, idx))
                     {
+                        // the branches differ in their messages, not after JSON_THROW's expansion
+                        // NOLINTNEXTLINE(bugprone-branch-clone)
                         case array_index_status::leading_zero:
                             JSON_THROW(detail::parse_error::create(106, 0, detail::concat("array index '", reference_token, "' must not begin with '0'"), nullptr));
                         case array_index_status::not_a_number:
@@ -23485,18 +23489,18 @@ class binary_writer
         switch (error_handler)
         {
             case error_handler_t::keep:
-                return s;
+                return s; // NOLINT(bugprone-return-const-ref-from-parameter): callers pass lvalues that outlive the call
 
             case error_handler_t::strict:
                 check_utf8(s, context);
-                return s;
+                return s; // NOLINT(bugprone-return-const-ref-from-parameter): callers pass lvalues that outlive the call
 
             case error_handler_t::replace:
             case error_handler_t::ignore:
             default:
                 if (is_valid_utf8(s))
                 {
-                    return s;
+                    return s; // NOLINT(bugprone-return-const-ref-from-parameter): callers pass lvalues that outlive the call
                 }
                 storage = sanitize_utf8(s, error_handler);
                 return storage;
@@ -25681,6 +25685,11 @@ class serializer
     @a ensure_ascii is a template parameter here so that the branch on it is
     resolved once, outside the loop; see @ref dump_escaped.
     */
+#ifdef JSON_HEDLEY_MSVC_VERSION
+#pragma warning(push)
+    // EnsureAscii is a template parameter; C++11 has no if constexpr
+#pragma warning(disable : 4127) // conditional expression is constant
+#endif
     template<bool EnsureAscii>
     void dump_escaped_impl(const string_t& s)
     {
@@ -26030,6 +26039,9 @@ class serializer
             }
         }
     }
+#ifdef JSON_HEDLEY_MSVC_VERSION
+#pragma warning(pop)
+#endif
 
   private:
     /*!
@@ -26612,7 +26624,7 @@ NLOHMANN_JSON_NAMESPACE_END
 #include <functional> // equal_to, less
 #include <initializer_list> // initializer_list
 #include <iterator> // input_iterator_tag, iterator_traits
-#include <memory> // allocator
+#include <memory> // allocator // IWYU pragma: keep
 #include <new> // for operator new (placement new)
 #include <stdexcept> // for out_of_range
 #include <tuple> // forward_as_tuple
@@ -26681,7 +26693,7 @@ private:
     /// @brief find the entry for @a key, for either constness of @a self
     /// @note the single place that performs the linear key search
     template<typename Self, typename KeyType>
-    static auto find_impl(Self& self, KeyType&& key) -> decltype(self.begin())
+    static auto find_impl(Self& self, const KeyType& key) -> decltype(self.begin())
     {
         for (auto it = self.begin(); it != self.end(); ++it)
         {
@@ -27985,6 +27997,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
           never name it to call this constructor itself.
     */
     basic_json(copy_construct_tag /*unused*/, const basic_json& src)
+    noexcept(std::is_nothrow_copy_constructible<json_base_class_t>::value)
         : json_base_class_t(src)
 #if JSON_DIAGNOSTIC_POSITIONS
         , start_position(src.start_position)
@@ -28379,7 +28392,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     be destroyed.
     */
     template<typename BasicJsonType>
-    void convert_iteratively(const BasicJsonType& val)
+    void convert_iteratively(const BasicJsonType& val, std::true_type /*unused*/)
     {
         using other_const_iterator = typename BasicJsonType::const_iterator;
 
@@ -28473,21 +28486,38 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 
         if (JSON_HEDLEY_LIKELY(guard.okay()))
         {
-            // every element comes back to the converting constructor
-            if (val.is_object())
-            {
-                using other_object_t = typename BasicJsonType::object_t;
-                JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
-            }
-            else
-            {
-                using other_array_t = typename BasicJsonType::array_t;
-                JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
-            }
+            convert_by_serializers(val);
             return;
         }
 
-        convert_iteratively(val);
+        // the iterative conversion needs to construct this object type's keys
+        // from those of @a val; if it cannot, neither can the range constructor,
+        // and the serializers convert @a val some other way (see #3425)
+        convert_iteratively(val, std::is_constructible<typename object_t::key_type, const typename BasicJsonType::string_t&> {});
+    }
+
+    /// @brief convert the object or array @a val with the serializers; every
+    /// element comes back to the converting constructor
+    template<typename BasicJsonType>
+    void convert_by_serializers(const BasicJsonType& val)
+    {
+        if (val.is_object())
+        {
+            using other_object_t = typename BasicJsonType::object_t;
+            JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
+        }
+        else
+        {
+            using other_array_t = typename BasicJsonType::array_t;
+            JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
+        }
+    }
+
+    /// @brief convert @a val whose keys cannot be converted, see @ref convert_structured
+    template<typename BasicJsonType>
+    void convert_iteratively(const BasicJsonType& val, std::false_type /*unused*/)
+    {
+        convert_by_serializers(val);
     }
 
 
@@ -28561,15 +28591,15 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static compare_result compare_leaves(const_reference lhs, const_reference rhs, std::true_type /*ordered*/) noexcept
     {
         const std::partial_ordering order = lhs <=> rhs; // *NOPAD*
-        if (order == 0)
+        if (std::is_eq(order))
         {
             return compare_result::equal;
         }
-        if (order < 0)
+        if (std::is_lt(order))
         {
             return compare_result::less;
         }
-        if (order > 0)
+        if (std::is_gt(order))
         {
             return compare_result::greater;
         }
@@ -31995,7 +32025,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_le/
     template<typename ScalarType>
     requires std::is_scalar_v<ScalarType>
-    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept
+    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) <= rhs;
     }
@@ -32004,7 +32034,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ge/
     template<typename ScalarType>
     requires std::is_scalar_v<ScalarType>
-    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept
+    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) >= rhs;
     }

tests/src/test_utils.hpp

@@ -10,7 +10,8 @@
 
 #include <cstdint> // uint8_t
 #include <cstddef> // size_t
-#include <fstream> // ifstream, istreambuf_iterator, ios
+#include <fstream> // ifstream, ios
+#include <iterator> // istream_iterator
 #include <vector> // vector
 
 namespace utils

tests/src/unit-allocator.cpp

@@ -567,7 +567,7 @@ struct allocator_no_forward : std::allocator<T>
 {
     allocator_no_forward() = default;
     template <class U>
-    allocator_no_forward(allocator_no_forward<U> /*unused*/) {}
+    allocator_no_forward(const allocator_no_forward<U>& /*unused*/) {}
 
     template <class U>
     struct rebind

tests/src/unit-binary_utf8_error_handler.cpp

@@ -7,6 +7,7 @@
 // SPDX-License-Identifier: MIT
 
 #include "doctest_compatibility.h"
+#include "test_utils.hpp"
 
 #include <nlohmann/json.hpp>
 using nlohmann::json;
@@ -25,18 +26,27 @@ struct ill_formed_case
 
 // RFC 3629 ill-formed sequences used throughout this file, plus one
 // well-formed sequence for contrast
-const std::vector<ill_formed_case> ill_formed_cases =
+std::vector<ill_formed_case> ill_formed_cases()
 {
-    {"overlong", "\xC0\xAE"},
-    {"lone_0xFF", "\xFF"},
-    {"truncated", "\xE2\x82"},
-    {"surrogate", "\xED\xA0\x80"},
-};
+    return
+    {
+        {"overlong", "\xC0\xAE"},
+        {"lone_0xFF", "\xFF"},
+        {"truncated", "\xE2\x82"},
+        {"surrogate", "\xED\xA0\x80"},
+    };
+}
 
-const std::string valid_sequence = "\xC3\xA9"; // U+00E9, "é"
+std::string valid_sequence()
+{
+    return "\xC3\xA9"; // U+00E9, "é"
+}
 
 using eh = json::error_handler_t;
-const std::vector<eh> all_handlers = {eh::strict, eh::replace, eh::ignore, eh::keep};
+std::vector<eh> all_handlers()
+{
+    return {eh::strict, eh::replace, eh::ignore, eh::keep};
+}
 
 // what dump()+parse() produces for a sanitizing error_handler; this is the
 // ground truth every binary writer/reader is checked against
@@ -51,9 +61,9 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
 {
     SECTION("writers: string value")
     {
-        for (const auto& c : ill_formed_cases)
+        for (const auto& c : ill_formed_cases())
         {
-            CAPTURE(c.name);
+            CAPTURE(c.name)
             const json jval = c.bytes;
 
             CHECK_THROWS_AS(json::to_cbor(jval, eh::strict), json::type_error&);
@@ -71,7 +81,7 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
                         eh::replace, eh::ignore
                     })
             {
-                CAPTURE(static_cast<int>(h));
+                CAPTURE(static_cast<int>(h))
                 const std::string expected = dump_and_parse(c.bytes, h);
 
                 CHECK(json::from_cbor(json::to_cbor(jval, h)).get<std::string>() == expected);
@@ -103,9 +113,9 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
 
     SECTION("writers: object key")
     {
-        for (const auto& c : ill_formed_cases)
+        for (const auto& c : ill_formed_cases())
         {
-            CAPTURE(c.name);
+            CAPTURE(c.name)
             json jobj;
             jobj[c.bytes] = 1;
 
@@ -120,7 +130,7 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
                         eh::replace, eh::ignore
                     })
             {
-                CAPTURE(static_cast<int>(h));
+                CAPTURE(static_cast<int>(h))
                 const std::string expected = dump_and_parse(c.bytes, h);
 
                 CHECK(json::from_cbor(json::to_cbor(jobj, h)).begin().key() == expected);
@@ -141,9 +151,9 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
 
     SECTION("readers: string value")
     {
-        for (const auto& c : ill_formed_cases)
+        for (const auto& c : ill_formed_cases())
         {
-            CAPTURE(c.name);
+            CAPTURE(c.name)
 
             // bytes produced the lenient (keep) way, as any binary reader
             // accepted them before this parameter existed
@@ -166,15 +176,15 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
             CHECK(json::from_bson(bson_bytes)["k"].get<std::string>() == c.bytes);
 
             // strict: parse_error.113, discarded (not thrown) when allow_exceptions is false
-            CHECK_THROWS_AS(json::from_cbor(cbor_bytes, true, true, json::cbor_tag_handler_t::error, eh::strict), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_cbor(cbor_bytes, true, true, json::cbor_tag_handler_t::error, eh::strict)), json::parse_error&);
             CHECK(json::from_cbor(cbor_bytes, true, false, json::cbor_tag_handler_t::error, eh::strict).is_discarded());
-            CHECK_THROWS_AS(json::from_msgpack(msgpack_bytes, true, true, eh::strict), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_msgpack(msgpack_bytes, true, true, eh::strict)), json::parse_error&);
             CHECK(json::from_msgpack(msgpack_bytes, true, false, eh::strict).is_discarded());
-            CHECK_THROWS_AS(json::from_ubjson(ubjson_bytes, true, true, eh::strict), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_ubjson(ubjson_bytes, true, true, eh::strict)), json::parse_error&);
             CHECK(json::from_ubjson(ubjson_bytes, true, false, eh::strict).is_discarded());
-            CHECK_THROWS_AS(json::from_bjdata(bjdata_bytes, true, true, eh::strict), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_bjdata(bjdata_bytes, true, true, eh::strict)), json::parse_error&);
             CHECK(json::from_bjdata(bjdata_bytes, true, false, eh::strict).is_discarded());
-            CHECK_THROWS_AS(json::from_bson(bson_bytes, true, true, eh::strict), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_bson(bson_bytes, true, true, eh::strict)), json::parse_error&);
             CHECK(json::from_bson(bson_bytes, true, false, eh::strict).is_discarded());
 
             // replace / ignore: match what dump() would have sanitized the same bytes to
@@ -183,7 +193,7 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
                         eh::replace, eh::ignore
                     })
             {
-                CAPTURE(static_cast<int>(h));
+                CAPTURE(static_cast<int>(h))
                 const std::string expected = dump_and_parse(c.bytes, h);
 
                 CHECK(json::from_cbor(cbor_bytes, true, true, json::cbor_tag_handler_t::error, h).get<std::string>() == expected);
@@ -197,9 +207,9 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
 
     SECTION("readers: object key")
     {
-        for (const auto& c : ill_formed_cases)
+        for (const auto& c : ill_formed_cases())
         {
-            CAPTURE(c.name);
+            CAPTURE(c.name)
 
             json jobj;
             jobj[c.bytes] = 1;
@@ -215,18 +225,18 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
             CHECK(json::from_bjdata(bjdata_bytes).begin().key() == c.bytes);
             CHECK(json::from_bson(bson_bytes).begin().key() == c.bytes);
 
-            CHECK_THROWS_AS(json::from_cbor(cbor_bytes, true, true, json::cbor_tag_handler_t::error, eh::strict), json::parse_error&);
-            CHECK_THROWS_AS(json::from_msgpack(msgpack_bytes, true, true, eh::strict), json::parse_error&);
-            CHECK_THROWS_AS(json::from_ubjson(ubjson_bytes, true, true, eh::strict), json::parse_error&);
-            CHECK_THROWS_AS(json::from_bjdata(bjdata_bytes, true, true, eh::strict), json::parse_error&);
-            CHECK_THROWS_AS(json::from_bson(bson_bytes, true, true, eh::strict), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_cbor(cbor_bytes, true, true, json::cbor_tag_handler_t::error, eh::strict)), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_msgpack(msgpack_bytes, true, true, eh::strict)), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_ubjson(ubjson_bytes, true, true, eh::strict)), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_bjdata(bjdata_bytes, true, true, eh::strict)), json::parse_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(json::from_bson(bson_bytes, true, true, eh::strict)), json::parse_error&);
 
             for (const auto h :
                     {
                         eh::replace, eh::ignore
                     })
             {
-                CAPTURE(static_cast<int>(h));
+                CAPTURE(static_cast<int>(h))
                 const std::string expected = dump_and_parse(c.bytes, h);
 
                 CHECK(json::from_cbor(cbor_bytes, true, true, json::cbor_tag_handler_t::error, h).begin().key() == expected);
@@ -240,30 +250,30 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
 
     SECTION("well-formed UTF-8 is unaffected by error_handler")
     {
-        const json jval = valid_sequence;
+        const json jval = valid_sequence();
         json jobj;
-        jobj[valid_sequence] = valid_sequence;
+        jobj[valid_sequence()] = valid_sequence();
 
-        for (const auto h : all_handlers)
+        for (const auto h : all_handlers())
         {
-            CAPTURE(static_cast<int>(h));
+            CAPTURE(static_cast<int>(h))
 
-            CHECK(json::from_cbor(json::to_cbor(jval, h)).get<std::string>() == valid_sequence);
-            CHECK(json::from_msgpack(json::to_msgpack(jval, h)).get<std::string>() == valid_sequence);
-            CHECK(json::from_ubjson(json::to_ubjson(jval, false, false, h)).get<std::string>() == valid_sequence);
-            CHECK(json::from_bjdata(json::to_bjdata(jval, false, false, json::bjdata_version_t::draft2, h)).get<std::string>() == valid_sequence);
-            CHECK(json::from_bson(json::to_bson(jobj, h)).begin().key() == valid_sequence);
+            CHECK(json::from_cbor(json::to_cbor(jval, h)).get<std::string>() == valid_sequence());
+            CHECK(json::from_msgpack(json::to_msgpack(jval, h)).get<std::string>() == valid_sequence());
+            CHECK(json::from_ubjson(json::to_ubjson(jval, false, false, h)).get<std::string>() == valid_sequence());
+            CHECK(json::from_bjdata(json::to_bjdata(jval, false, false, json::bjdata_version_t::draft2, h)).get<std::string>() == valid_sequence());
+            CHECK(json::from_bson(json::to_bson(jobj, h)).begin().key() == valid_sequence());
 
-            CHECK(json::from_cbor(json::to_cbor(jval, eh::keep), true, true, json::cbor_tag_handler_t::error, h).get<std::string>() == valid_sequence);
-            CHECK(json::from_msgpack(json::to_msgpack(jval), true, true, h).get<std::string>() == valid_sequence);
+            CHECK(json::from_cbor(json::to_cbor(jval, eh::keep), true, true, json::cbor_tag_handler_t::error, h).get<std::string>() == valid_sequence());
+            CHECK(json::from_msgpack(json::to_msgpack(jval), true, true, h).get<std::string>() == valid_sequence());
         }
     }
 
     SECTION("dump() with error_handler_t::keep writes raw bytes as is")
     {
-        for (const auto& c : ill_formed_cases)
+        for (const auto& c : ill_formed_cases())
         {
-            CAPTURE(c.name);
+            CAPTURE(c.name)
 
             const json jval = c.bytes;
             const std::string dumped = jval.dump(-1, ' ', false, eh::keep);
@@ -276,10 +286,10 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
 
         // well-formed characters around an ill-formed sequence are still
         // escaped as usual under ensure_ascii
-        const json mixed = valid_sequence + ill_formed_cases[1].bytes; // "é" + lone 0xFF
+        const json mixed = valid_sequence() + ill_formed_cases()[1].bytes; // "é" + lone 0xFF
         const std::string dumped_mixed = mixed.dump(-1, ' ', true, eh::keep);
         CHECK(dumped_mixed.find("\\u00e9") != std::string::npos);
-        CHECK(dumped_mixed.find(ill_formed_cases[1].bytes) != std::string::npos);
+        CHECK(dumped_mixed.find(ill_formed_cases()[1].bytes) != std::string::npos);
 
         // the byte that ends an ill-formed sequence is read again, so a quote,
         // a backslash, or a control character after it is still escaped, and
@@ -289,7 +299,7 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
                     false, true
                 })
         {
-            CAPTURE(ensure_ascii);
+            CAPTURE(ensure_ascii)
             CHECK(json("\xC3\"").dump(-1, ' ', ensure_ascii, eh::keep) == "\"\xC3\\\"\"");
             CHECK(json("\xC3\\").dump(-1, ' ', ensure_ascii, eh::keep) == "\"\xC3\\\\\"");
             CHECK(json("\xC3\n").dump(-1, ' ', ensure_ascii, eh::keep) == "\"\xC3\\n\"");
@@ -303,12 +313,12 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
 
     SECTION("to_msgpack defaults to keep; to_bon8 is not affected by error_handler")
     {
-        const json jval = ill_formed_cases[1].bytes; // lone 0xFF
+        const json jval = ill_formed_cases()[1].bytes; // lone 0xFF
 
         // to_msgpack's error_handler defaults to keep, as MessagePack's spec
         // allows any bytes in a str, so the bytes are passed through
         CHECK(json::to_msgpack(jval) == json::to_msgpack(jval, eh::keep));
-        CHECK(json::from_msgpack(json::to_msgpack(jval)).get<std::string>() == ill_formed_cases[1].bytes);
+        CHECK(json::from_msgpack(json::to_msgpack(jval)).get<std::string>() == ill_formed_cases()[1].bytes);
 
         // the diagnostics context of an ill-formed key is the object
         json jobj;
@@ -322,14 +332,14 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
 
     SECTION("allow_exceptions=false with error_handler_t::strict discards the value")
     {
-        const auto bytes = json::to_cbor(json(ill_formed_cases[0].bytes), eh::keep);
+        const auto bytes = json::to_cbor(json(ill_formed_cases()[0].bytes), eh::keep);
         const json result = json::from_cbor(bytes, true, false, json::cbor_tag_handler_t::error, eh::strict);
         CHECK(result.is_discarded());
     }
 
     SECTION("default parameters are unchanged")
     {
-        const json jval = ill_formed_cases[0].bytes;
+        const json jval = ill_formed_cases()[0].bytes;
 
         // to_*: the default error_handler is keep, so ill-formed bytes are
         // written unchanged, exactly as in release 3.12.0 (it is strict only
@@ -347,16 +357,16 @@ TEST_CASE("UTF-8 error_handler for the binary readers and writers")
         // from_*: the default error_handler is keep, so ill-formed bytes are
         // still accepted unchanged, exactly as in release 3.12.0
         const auto cbor_bytes = json::to_cbor(jval, eh::keep);
-        CHECK(json::from_cbor(cbor_bytes).get<std::string>() == ill_formed_cases[0].bytes);
+        CHECK(json::from_cbor(cbor_bytes).get<std::string>() == ill_formed_cases()[0].bytes);
         const auto ubjson_bytes = json::to_ubjson(jval, false, false, eh::keep);
-        CHECK(json::from_ubjson(ubjson_bytes).get<std::string>() == ill_formed_cases[0].bytes);
+        CHECK(json::from_ubjson(ubjson_bytes).get<std::string>() == ill_formed_cases()[0].bytes);
         const auto bjdata_bytes = json::to_bjdata(jval, false, false, json::bjdata_version_t::draft2, eh::keep);
-        CHECK(json::from_bjdata(bjdata_bytes).get<std::string>() == ill_formed_cases[0].bytes);
+        CHECK(json::from_bjdata(bjdata_bytes).get<std::string>() == ill_formed_cases()[0].bytes);
         const auto msgpack_bytes = json::to_msgpack(jval);
-        CHECK(json::from_msgpack(msgpack_bytes).get<std::string>() == ill_formed_cases[0].bytes);
+        CHECK(json::from_msgpack(msgpack_bytes).get<std::string>() == ill_formed_cases()[0].bytes);
         json bson_obj;
         bson_obj["k"] = jval;
         const auto bson_bytes = json::to_bson(bson_obj, eh::keep);
-        CHECK(json::from_bson(bson_bytes)["k"].get<std::string>() == ill_formed_cases[0].bytes);
+        CHECK(json::from_bson(bson_bytes)["k"].get<std::string>() == ill_formed_cases()[0].bytes);
     }
 }

tests/src/unit-binary_utf8_strict.cpp

@@ -83,21 +83,45 @@ TEST_CASE("JSON_STRICT_BINARY_UTF8 (see #5529, #5651)")
         // any bytes reach the output adapter (the BSON document length
         // prefix must be known up front, so nothing is written incrementally)
         std::vector<std::uint8_t> out{0x42}; // a sentinel byte the writer must not touch
-        CHECK_THROWS_WITH_AS(json::to_bson(json{{"s", "\xFF"}}, nlohmann::detail::output_adapter<std::uint8_t>(out)), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xFF", json::type_error&);
+#if JSON_DIAGNOSTICS
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xFF"}}, nlohmann::detail::output_adapter<std::uint8_t>(out)), "[json.exception.type_error.316] (/s) invalid UTF-8 byte at index 0: 0xFF", json::type_error&);
+#else
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xFF"}}, nlohmann::detail::output_adapter<std::uint8_t>(out)), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xFF", json::type_error&);
+#endif
         CHECK(out == std::vector<std::uint8_t> {0x42});
 
-        CHECK_THROWS_WITH_AS(json::to_bson(json{{"s", "\xFF"}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xFF", json::type_error&);
+#if JSON_DIAGNOSTICS
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xFF"}}), "[json.exception.type_error.316] (/s) invalid UTF-8 byte at index 0: 0xFF", json::type_error&);
+#else
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xFF"}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xFF", json::type_error&);
+#endif
         // a truncated multi-byte sequence
-        CHECK_THROWS_WITH_AS(json::to_bson(json{{"s", "\xC3"}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xC3", json::type_error&);
+#if JSON_DIAGNOSTICS
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xC3"}}), "[json.exception.type_error.316] (/s) invalid UTF-8 byte at index 0: 0xC3", json::type_error&);
+#else
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xC3"}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xC3", json::type_error&);
+#endif
         // an encoded surrogate half (U+D800)
-        CHECK_THROWS_WITH_AS(json::to_bson(json{{"s", "\xED\xA0\x80"}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xED", json::type_error&);
+#if JSON_DIAGNOSTICS
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xED\xA0\x80"}}), "[json.exception.type_error.316] (/s) invalid UTF-8 byte at index 0: 0xED", json::type_error&);
+#else
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xED\xA0\x80"}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xED", json::type_error&);
+#endif
         // an overlong encoding of '.'
-        CHECK_THROWS_WITH_AS(json::to_bson(json{{"s", "\xC0\xAF"}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xC0", json::type_error&);
+#if JSON_DIAGNOSTICS
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xC0\xAF"}}), "[json.exception.type_error.316] (/s) invalid UTF-8 byte at index 0: 0xC0", json::type_error&);
+#else
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"s", "\xC0\xAF"}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xC0", json::type_error&);
+#endif
 
         // an object key with ill-formed UTF-8 is rejected as well; unlike
         // the reader (which never validates element names), the writer
         // checks both string values and object keys
-        CHECK_THROWS_WITH_AS(json::to_bson(json{{"\xFF", 1}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xFF", json::type_error&);
+#if JSON_DIAGNOSTICS
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"\xFF", 1}}), "[json.exception.type_error.316] (/\xFF) invalid UTF-8 byte at index 0: 0xFF", json::type_error&);
+#else
+        CHECK_THROWS_WITH_AS(json::to_bson(json {{"\xFF", 1}}), "[json.exception.type_error.316] invalid UTF-8 byte at index 0: 0xFF", json::type_error&);
+#endif
     }
 
     SECTION("an explicit error_handler overrides the default")

tests/src/unit-bjdata.cpp

@@ -3921,7 +3921,7 @@ TEST_CASE("Universal Binary JSON Specification Examples 1")
             CHECK_NOTHROW(j = json::from_bjdata(v));
             REQUIRE(j.is_string());
             CHECK(j.get_ref<const json::string_t&>() == std::string("\xc0\xae"));
-            CHECK_THROWS_AS(j.dump(), json::type_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(j.dump()), json::type_error&);
             CHECK(json::from_bjdata(json::to_bjdata(j)) == j);
 
             // the same bytes as an object key round-trip as well

tests/src/unit-bon8.cpp

@@ -786,6 +786,7 @@ TEST_CASE("Parse BON8 directly from a file using iterator and sentinel")
     CHECK((parsed.is_object() || parsed.is_array()));
 }
 
+#if !defined(JSON_NOEXCEPTION) // corpus values that do not survive the round trip are skipped by catching the exception
 TEST_CASE("BON8 round-trip invariants")
 {
     // This checks what the parse_bon8_fuzzer driver checks (see
@@ -818,6 +819,7 @@ TEST_CASE("BON8 round-trip invariants")
         CHECK(json::to_bon8(j2) == vec);
     }
 }
+#endif
 
 TEST_CASE("BON8 roundtrips" * doctest::skip())
 {

tests/src/unit-bson.cpp

@@ -62,6 +62,8 @@ class huge_string_t : public std::string
 {
   public:
     using std::string::string;
+    // inheriting std::string's constructors does not inherit its default constructor
+    huge_string_t() = default;
     huge_string_t(const std::string& s) : std::string(s) {} // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
 
     // returns a copy of @a s whose size() pretends to be huge
@@ -174,7 +176,7 @@ TEST_CASE("BSON")
         REQUIRE(j.contains("s"));
         CHECK(j["s"].get_ref<const json::string_t&>() == std::string("\xc0\xae"));
         // dump() still requires valid UTF-8 and throws for such a value
-        CHECK_THROWS_AS(j.dump(), json::type_error&);
+        CHECK_THROWS_AS(utils::ignore_return_value(j.dump()), json::type_error&);
         // to_bson() writes the bytes back unchanged, as before 3.13.0,
         // unless JSON_STRICT_BINARY_UTF8 is enabled (see unit-binary_utf8_strict.cpp)
         CHECK(json::from_bson(json::to_bson(j)) == j);

tests/src/unit-cbor.cpp

@@ -1820,7 +1820,7 @@ TEST_CASE("CBOR")
             // dump() still requires valid UTF-8 and throws for such a value,
             // unless an error handler that replaces or ignores the bytes is
             // passed
-            CHECK_THROWS_AS(j_value.dump(), json::type_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(j_value.dump()), json::type_error&);
             // to_cbor() writes the bytes back unchanged, as before 3.13.0,
             // unless JSON_STRICT_BINARY_UTF8 is enabled (see unit-binary_utf8_strict.cpp)
             CHECK(json::from_cbor(json::to_cbor(j_value)) == j_value);
@@ -1878,13 +1878,13 @@ TEST_CASE("CBOR")
             // a truncated code point is kept as is
             CHECK_NOTHROW(_ = json::from_cbor(std::vector<uint8_t>({0x7f, 0x61, 0xc3, 0xff})));
             CHECK(_ == "\xc3");
-            CHECK_THROWS_AS(_.dump(), json::type_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(_.dump()), json::type_error&);
             CHECK(json::from_cbor(json::to_cbor(_)) == _);
 
             // an ill-formed later chunk is kept after valid ones
             CHECK_NOTHROW(_ = json::from_cbor(std::vector<uint8_t>({0x7f, 0x62, 0xc3, 0xa9, 0x62, 0xc0, 0xae, 0xff})));
             CHECK(_ == "\xc3\xa9\xc0\xae");
-            CHECK_THROWS_AS(_.dump(), json::type_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(_.dump()), json::type_error&);
 
             // valid multi-byte chunks are accepted
             CHECK(json::from_cbor(std::vector<uint8_t>({0x7f, 0x62, 0xc3, 0xa9, 0x62, 0xc3, 0xb6, 0xff})) == "\xc3\xa9\xc3\xb6");
@@ -2390,6 +2390,7 @@ TEST_CASE("issue #5405 - array reserve for definite-length CBOR arrays")
     }
 }
 
+#if !defined(JSON_NOEXCEPTION) // corpus values that do not survive the round trip are skipped by catching the exception
 TEST_CASE("CBOR round-trip invariants")
 {
     // This checks what the parse_cbor_fuzzer driver checks (see
@@ -2422,6 +2423,7 @@ TEST_CASE("CBOR round-trip invariants")
         CHECK(json::to_cbor(j2) == vec);
     }
 }
+#endif
 
 TEST_CASE("CBOR roundtrips" * doctest::skip())
 {

tests/src/unit-class_parser.cpp

@@ -2704,9 +2704,9 @@ TEST_CASE("diagnostic positions: value lifetime, input adapters, and SAX")
             CHECK(b["b"].end_pos() == nested_end);
 
             // the moved-from value is reset to a null and reports npos
-            CHECK(a.is_null()); // NOLINT(bugprone-use-after-move,clang-analyzer-cplusplus.Move)
-            CHECK(a.start_pos() == std::string::npos); // NOLINT(bugprone-use-after-move,clang-analyzer-cplusplus.Move)
-            CHECK(a.end_pos() == std::string::npos); // NOLINT(bugprone-use-after-move,clang-analyzer-cplusplus.Move)
+            CHECK(a.is_null()); // NOLINT(bugprone-use-after-move,hicpp-invalid-access-moved,clang-analyzer-cplusplus.Move)
+            CHECK(a.start_pos() == std::string::npos); // NOLINT(bugprone-use-after-move,hicpp-invalid-access-moved,clang-analyzer-cplusplus.Move)
+            CHECK(a.end_pos() == std::string::npos); // NOLINT(bugprone-use-after-move,hicpp-invalid-access-moved,clang-analyzer-cplusplus.Move)
         }
 
         SECTION("swap() exchanges positions along with values")

tests/src/unit-comparison.cpp

@@ -969,7 +969,7 @@ TEST_CASE("copying an object preserves its comparator's state")
 
     for (const std::size_t depth : std::vector<std::size_t> {0, 127, 128, 200})
     {
-        CAPTURE(depth);
+        CAPTURE(depth)
 
         key_case_json original = object;
         for (std::size_t i = 0; i < depth; ++i)
@@ -1138,7 +1138,7 @@ TEST_CASE("operator<=> of binary values with a different subtype does not depend
     // and must still agree with the levels that do
     for (const std::size_t depth : std::vector<std::size_t> {0, 127, 128, 200})
     {
-        CAPTURE(depth);
+        CAPTURE(depth)
         const json x = deep(a, depth);
         const json y = deep(b, depth);
         CHECK((x <=> y) == std::partial_ordering::less); // *NOPAD*

tests/src/unit-conversions1.cpp

@@ -15,11 +15,6 @@
 
 #include "doctest_compatibility.h"
 
-// skip tests if JSON_DisableEnumSerialization=ON (#4384)
-#if defined(JSON_DISABLE_ENUM_SERIALIZATION) && (JSON_DISABLE_ENUM_SERIALIZATION == 1)
-    #define SKIP_TESTS_FOR_ENUM_SERIALIZATION
-#endif
-
 #define JSON_TESTS_PRIVATE
 #include <nlohmann/json.hpp>
 using nlohmann::json;
@@ -1259,808 +1254,8 @@ TEST_CASE("value conversion")
         }
     }
 #endif
-
-    SECTION("get a binary value (explicit)")
-    {
-        json::binary_t const n_reference{{1, 2, 3}};
-        json j(n_reference);
-
-        SECTION("binary_t")
-        {
-            json::binary_t const b = j.get<json::binary_t>();
-            CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
-        }
-
-        SECTION("get_binary()")
-        {
-            SECTION("non-const")
-            {
-                auto& b = j.get_binary();
-                CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
-            }
-
-            SECTION("non-const")
-            {
-                const json j_const = j; // NOLINT(performance-unnecessary-copy-initialization)
-                const auto& b = j_const.get_binary();
-                CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
-            }
-        }
-
-        SECTION("exception in case of a non-string type")
-        {
-            json j_null(json::value_t::null);
-            json j_object(json::value_t::object);
-            json j_array(json::value_t::array);
-            json j_string(json::value_t::string);
-            json j_boolean(json::value_t::boolean);
-            const json j_null_const(json::value_t::null);
-            const json j_object_const(json::value_t::object);
-            const json j_array_const(json::value_t::array);
-            const json j_string_const(json::value_t::string);
-            const json j_boolean_const(json::value_t::boolean);
-
-            CHECK_THROWS_WITH_AS(j_null.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is null",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_object.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is object",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_array.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is array",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_string.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is string",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_boolean.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is boolean",
-                                 json::type_error&);
-
-            CHECK_THROWS_WITH_AS(j_null_const.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is null",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_object_const.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is object",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_array_const.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is array",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_string_const.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is string",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_boolean_const.get<json::binary_t>(),
-                                 "[json.exception.type_error.302] type must be binary, but is boolean",
-                                 json::type_error&);
-
-            CHECK_THROWS_WITH_AS(j_null.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is null",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_object.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is object",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_array.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is array",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_string.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is string",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_boolean.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is boolean",
-                                 json::type_error&);
-
-            CHECK_THROWS_WITH_AS(j_null_const.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is null",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_object_const.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is object",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_array_const.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is array",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_string_const.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is string",
-                                 json::type_error&);
-            CHECK_THROWS_WITH_AS(j_boolean_const.get_binary(),
-                                 "[json.exception.type_error.302] type must be binary, but is boolean",
-                                 json::type_error&);
-        }
-    }
-
-#if JSON_USE_IMPLICIT_CONVERSIONS
-    SECTION("get a binary value (implicit)")
-    {
-        json::binary_t const n_reference{{1, 2, 3}};
-        json const j(n_reference);
-
-        SECTION("binary_t")
-        {
-            json::binary_t const b = j;
-            CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
-        }
-    }
-#endif
-
-#ifndef SKIP_TESTS_FOR_ENUM_SERIALIZATION
-    SECTION("get an enum")
-    {
-        enum c_enum { value_1, value_2 }; // NOLINT(cppcoreguidelines-use-enum-class)
-        enum class cpp_enum { value_1, value_2 };
-
-        CHECK(json(value_1).get<c_enum>() == value_1);
-        CHECK(json(cpp_enum::value_1).get<cpp_enum>() == cpp_enum::value_1);
-    }
-
-    SECTION("get an enum with underlying type bool (#5671)")
-    {
-        enum class bool_enum : bool { off, on };
-
-        CHECK(json(bool_enum::off).get<bool_enum>() == bool_enum::off);
-        CHECK(json(bool_enum::on).get<bool_enum>() == bool_enum::on);
-    }
-#endif
-
-    SECTION("more involved conversions")
-    {
-        SECTION("object-like STL containers")
-        {
-            json const j1 = {{"one", 1}, {"two", 2}, {"three", 3}};
-            json const j2 = {{"one", 1u}, {"two", 2u}, {"three", 3u}};
-            json const j3 = {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}};
-            json const j4 = {{"one", true}, {"two", false}, {"three", true}};
-            json const j5 = {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}};
-
-            SECTION("std::map")
-            {
-                CHECK(j1.get<std::map<std::string, int>>() == (std::map<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
-                CHECK(j2.get<std::map<std::string, unsigned int>>() == (std::map<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
-                CHECK(j3.get<std::map<std::string, double>>() == (std::map<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
-                CHECK(j4.get<std::map<std::string, bool>>() == (std::map<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
-                CHECK(j5.get<std::map<std::string, std::string>>() == (std::map<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
-            }
-
-            SECTION("std::unordered_map")
-            {
-                CHECK(j1.get<std::unordered_map<std::string, int>>() == (std::unordered_map<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
-                CHECK(j2.get<std::unordered_map<std::string, unsigned int>>() == (std::unordered_map<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
-                CHECK(j3.get<std::unordered_map<std::string, double>>() == (std::unordered_map<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
-                CHECK(j4.get<std::unordered_map<std::string, bool>>() == (std::unordered_map<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
-                const auto m5 = j5.get<std::unordered_map<std::string, std::string>>();
-                CHECK(m5 == (std::unordered_map<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
-                CHECK(m5.at("one") == "eins");
-            }
-
-            SECTION("reserve is called on containers that support it (#5406)")
-            {
-                // build a larger object so that a missing/incorrect reserve()
-                // call would be more likely to corrupt or drop elements
-                json j_large;
-                for (int i = 0; i < 100; ++i)
-                {
-                    j_large[std::to_string(i)] = i;
-                }
-
-                SECTION("std::unordered_map (supports reserve)")
-                {
-                    const auto m = j_large.get<std::unordered_map<std::string, int>>();
-                    CHECK(m.size() == 100);
-                    for (int i = 0; i < 100; ++i)
-                    {
-                        CHECK(m.at(std::to_string(i)) == i);
-                    }
-                }
-
-                SECTION("std::map (no reserve, fallback path)")
-                {
-                    const auto m = j_large.get<std::map<std::string, int>>();
-                    CHECK(m.size() == 100);
-                    for (int i = 0; i < 100; ++i)
-                    {
-                        CHECK(m.at(std::to_string(i)) == i);
-                    }
-                }
-            }
-
-            SECTION("std::multimap")
-            {
-                CHECK(j1.get<std::multimap<std::string, int>>() == (std::multimap<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
-                CHECK(j2.get<std::multimap<std::string, unsigned int>>() == (std::multimap<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
-                CHECK(j3.get<std::multimap<std::string, double>>() == (std::multimap<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
-                CHECK(j4.get<std::multimap<std::string, bool>>() == (std::multimap<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
-                const auto m5 = j5.get<std::multimap<std::string, std::string>>();
-                CHECK(m5 == (std::multimap<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
-                CHECK(m5.find("one")->second == "eins");
-            }
-
-            SECTION("std::unordered_multimap")
-            {
-                CHECK(j1.get<std::unordered_multimap<std::string, int>>() == (std::unordered_multimap<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
-                CHECK(j2.get<std::unordered_multimap<std::string, unsigned int>>() == (std::unordered_multimap<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
-                CHECK(j3.get<std::unordered_multimap<std::string, double>>() == (std::unordered_multimap<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
-                CHECK(j4.get<std::unordered_multimap<std::string, bool>>() == (std::unordered_multimap<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
-                const auto m5 = j5.get<std::unordered_multimap<std::string, std::string>>();
-                CHECK(m5 == (std::unordered_multimap<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
-                CHECK(m5.find("one")->second == "eins");
-            }
-
-            SECTION("exception in case of a non-object type")
-            {
-                CHECK_THROWS_WITH_AS(
-                    (json().get<std::map<std::string, int>>()),
-                    "[json.exception.type_error.302] type must be object, but is null", json::type_error&);
-            }
-        }
-
-        SECTION("array-like STL containers")
-        {
-            json const j1 = {1, 2, 3, 4};
-            json const j2 = {1u, 2u, 3u, 4u};
-            json const j3 = {1.2, 2.3, 3.4, 4.5};
-            json const j4 = {true, false, true};
-            json const j5 = {"one", "two", "three"};
-
-            SECTION("std::list")
-            {
-                CHECK(j1.get<std::list<int>>() == (std::list<int> {1, 2, 3, 4}));
-                CHECK(j2.get<std::list<unsigned int>>() == (std::list<unsigned int> {1u, 2u, 3u, 4u}));
-                CHECK(j3.get<std::list<double>>() == (std::list<double> {1.2, 2.3, 3.4, 4.5}));
-                CHECK(j4.get<std::list<bool>>() == (std::list<bool> {true, false, true}));
-                CHECK(j5.get<std::list<std::string>>() == (std::list<std::string> {"one", "two", "three"}));
-            }
-
-            SECTION("std::forward_list")
-            {
-                CHECK(j1.get<std::forward_list<int>>() == (std::forward_list<int> {1, 2, 3, 4}));
-                CHECK(j2.get<std::forward_list<unsigned int>>() == (std::forward_list<unsigned int> {1u, 2u, 3u, 4u}));
-                CHECK(j3.get<std::forward_list<double>>() == (std::forward_list<double> {1.2, 2.3, 3.4, 4.5}));
-                CHECK(j4.get<std::forward_list<bool>>() == (std::forward_list<bool> {true, false, true}));
-                CHECK(j5.get<std::forward_list<std::string>>() == (std::forward_list<std::string> {"one", "two", "three"}));
-            }
-
-            SECTION("std::array")
-            {
-                CHECK(j1.get<std::array<int, 4>>() == (std::array<int, 4> {{1, 2, 3, 4}}));
-                // only the first 3 elements of j2 are converted, since the target array is smaller
-                CHECK(j2.get<std::array<unsigned int, 3>>() == (std::array<unsigned int, 3> {{1u, 2u, 3u}}));
-                CHECK(j3.get<std::array<double, 4>>() == (std::array<double, 4> {{1.2, 2.3, 3.4, 4.5}}));
-                CHECK(j4.get<std::array<bool, 3>>() == (std::array<bool, 3> {{true, false, true}}));
-                CHECK(j5.get<std::array<std::string, 3>>() == (std::array<std::string, 3> {{"one", "two", "three"}}));
-
-                SECTION("std::array is larger than JSON")
-                {
-                    std::array<int, 6> arr6 = {{1, 2, 3, 4, 5, 6}};
-                    CHECK_THROWS_WITH_AS(j1.get_to(arr6), "[json.exception.out_of_range.401] "
-                                         "array index 4 is out of range", json::out_of_range&);
-                }
-
-                SECTION("std::array is smaller than JSON")
-                {
-                    std::array<int, 2> arr2 = {{8, 9}};
-                    j1.get_to(arr2);
-                    CHECK(arr2[0] == 1);
-                    CHECK(arr2[1] == 2);
-                }
-            }
-
-            SECTION("std::valarray")
-            {
-                // valarray has no operator== that returns bool, so compare via a vector copy
-                const auto v1 = j1.get<std::valarray<int>>();
-                CHECK((std::vector<int>(std::begin(v1), std::end(v1)) == std::vector<int> {1, 2, 3, 4}));
-                const auto v2 = j2.get<std::valarray<unsigned int>>();
-                CHECK((std::vector<unsigned int>(std::begin(v2), std::end(v2)) == std::vector<unsigned int> {1u, 2u, 3u, 4u}));
-                const auto v3 = j3.get<std::valarray<double>>();
-                CHECK((std::vector<double>(std::begin(v3), std::end(v3)) == std::vector<double> {1.2, 2.3, 3.4, 4.5}));
-                const auto v4 = j4.get<std::valarray<bool>>();
-                CHECK((std::vector<bool>(std::begin(v4), std::end(v4)) == std::vector<bool> {true, false, true}));
-                const auto v5 = j5.get<std::valarray<std::string>>();
-                CHECK((std::vector<std::string>(std::begin(v5), std::end(v5)) == std::vector<std::string> {"one", "two", "three"}));
-            }
-
-            SECTION("std::vector")
-            {
-                CHECK(j1.get<std::vector<int>>() == (std::vector<int> {1, 2, 3, 4}));
-                CHECK(j2.get<std::vector<unsigned int>>() == (std::vector<unsigned int> {1u, 2u, 3u, 4u}));
-                CHECK(j3.get<std::vector<double>>() == (std::vector<double> {1.2, 2.3, 3.4, 4.5}));
-                CHECK(j4.get<std::vector<bool>>() == (std::vector<bool> {true, false, true}));
-                CHECK(j5.get<std::vector<std::string>>() == (std::vector<std::string> {"one", "two", "three"}));
-            }
-
-            SECTION("std::deque")
-            {
-                CHECK(j1.get<std::deque<int>>() == (std::deque<int> {1, 2, 3, 4}));
-                CHECK(j2.get<std::deque<unsigned int>>() == (std::deque<unsigned int> {1u, 2u, 3u, 4u}));
-                CHECK(j3.get<std::deque<double>>() == (std::deque<double> {1.2, 2.3, 3.4, 4.5}));
-                CHECK(j4.get<std::deque<bool>>() == (std::deque<bool> {true, false, true}));
-                CHECK(j5.get<std::deque<std::string>>() == (std::deque<std::string> {"one", "two", "three"}));
-            }
-
-            SECTION("std::set")
-            {
-                CHECK(j1.get<std::set<int>>() == (std::set<int> {1, 2, 3, 4}));
-                CHECK(j2.get<std::set<unsigned int>>() == (std::set<unsigned int> {1u, 2u, 3u, 4u}));
-                CHECK(j3.get<std::set<double>>() == (std::set<double> {1.2, 2.3, 3.4, 4.5}));
-                CHECK(j4.get<std::set<bool>>() == (std::set<bool> {true, false, true}));
-                CHECK(j5.get<std::set<std::string>>() == (std::set<std::string> {"one", "two", "three"}));
-            }
-
-            SECTION("std::unordered_set")
-            {
-                CHECK(j1.get<std::unordered_set<int>>() == (std::unordered_set<int> {1, 2, 3, 4}));
-                CHECK(j2.get<std::unordered_set<unsigned int>>() == (std::unordered_set<unsigned int> {1u, 2u, 3u, 4u}));
-                CHECK(j3.get<std::unordered_set<double>>() == (std::unordered_set<double> {1.2, 2.3, 3.4, 4.5}));
-                CHECK(j4.get<std::unordered_set<bool>>() == (std::unordered_set<bool> {true, false, true}));
-                CHECK(j5.get<std::unordered_set<std::string>>() == (std::unordered_set<std::string> {"one", "two", "three"}));
-            }
-
-            SECTION("std::map (array of pairs)")
-            {
-                const std::map<int, int> m{{0, 1}, {1, 2}, {2, 3}};
-                json const j6 = m;
-
-                auto m2 = j6.get<std::map<int, int>>();
-                CHECK(m == m2);
-
-                json const j7 = {0, 1, 2, 3};
-                json const j8 = 2;
-#if JSON_DIAGNOSTICS
-                CHECK_THROWS_WITH_AS((j7.get<std::map<int, int>>()),
-                                     "[json.exception.type_error.302] (/0) type must be array, "
-                                     "but is number", json::type_error&);
-#else
-                CHECK_THROWS_WITH_AS((j7.get<std::map<int, int>>()),
-                                     "[json.exception.type_error.302] type must be array, "
-                                     "but is number", json::type_error&);
-#endif
-                CHECK_THROWS_WITH_AS((j8.get<std::map<int, int>>()),
-                                     "[json.exception.type_error.302] type must be array, "
-                                     "but is number", json::type_error&);
-
-                SECTION("superfluous entries")
-                {
-                    json const j9 = {{0, 1, 2}, {1, 2, 3}, {2, 3, 4}};
-                    m2 = j9.get<std::map<int, int>>();
-                    CHECK(m == m2);
-                }
-            }
-
-            SECTION("std::unordered_map (array of pairs)")
-            {
-                const std::unordered_map<int, int> m{{0, 1}, {1, 2}, {2, 3}};
-                json const j6 = m;
-
-                auto m2 = j6.get<std::unordered_map<int, int>>();
-                CHECK(m == m2);
-
-                json const j7 = {0, 1, 2, 3};
-                json const j8 = 2;
-#if JSON_DIAGNOSTICS
-                CHECK_THROWS_WITH_AS((j7.get<std::unordered_map<int, int>>()),
-                                     "[json.exception.type_error.302] (/0) type must be array, "
-                                     "but is number", json::type_error&);
-#else
-                CHECK_THROWS_WITH_AS((j7.get<std::unordered_map<int, int>>()),
-                                     "[json.exception.type_error.302] type must be array, "
-                                     "but is number", json::type_error&);
-#endif
-                CHECK_THROWS_WITH_AS((j8.get<std::unordered_map<int, int>>()),
-                                     "[json.exception.type_error.302] type must be array, "
-                                     "but is number", json::type_error&);
-
-                SECTION("superfluous entries")
-                {
-                    json const j9{{0, 1, 2}, {1, 2, 3}, {2, 3, 4}};
-                    m2 = j9.get<std::unordered_map<int, int>>();
-                    CHECK(m == m2);
-                }
-            }
-
-            SECTION("exception in case of a non-object type")
-            {
-                // does type really must be an array? or it rather must not be null?
-                // that's what I thought when other test like this one broke
-                CHECK_THROWS_WITH_AS(
-                    (json().get<std::list<int>>()),
-                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
-                CHECK_THROWS_WITH_AS(
-                    (json().get<std::vector<int>>()),
-                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
-                CHECK_THROWS_WITH_AS(
-                    (json().get<std::vector<json>>()),
-                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
-                CHECK_THROWS_WITH_AS(
-                    (json().get<std::list<json>>()),
-                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
-                CHECK_THROWS_WITH_AS(
-                    (json().get<std::valarray<int>>()),
-                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
-                CHECK_THROWS_WITH_AS(
-                    (json().get<std::map<int, int>>()),
-                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
-            }
-        }
-    }
 }
 
-enum class cards {kreuz, pik, herz, karo};
-
-// NOLINTNEXTLINE(misc-use-internal-linkage,misc-const-correctness) - false positive
-NLOHMANN_JSON_SERIALIZE_ENUM(cards,
-{
-    {cards::kreuz, "kreuz"},
-    {cards::pik, "pik"},
-    {cards::pik, "puk"},  // second entry for cards::puk; will not be used
-    {cards::herz, "herz"},
-    {cards::karo, "karo"}
-})
-
-enum TaskState // NOLINT(cert-int09-c,readability-enum-initial-value,cppcoreguidelines-use-enum-class)
-{
-    TS_STOPPED,
-    TS_RUNNING,
-    TS_COMPLETED,
-    TS_INVALID = -1,
-};
-
-// NOLINTNEXTLINE(misc-const-correctness,misc-use-internal-linkage) - false positive
-NLOHMANN_JSON_SERIALIZE_ENUM(TaskState,
-{
-    {TS_INVALID, nullptr},
-    {TS_STOPPED, "stopped"},
-    {TS_RUNNING, "running"},
-    {TS_COMPLETED, "completed"},
-})
-
-TEST_CASE("JSON to enum mapping")
-{
-    SECTION("enum class")
-    {
-        // enum -> json
-        CHECK(json(cards::kreuz) == "kreuz");
-        CHECK(json(cards::pik) == "pik");
-        CHECK(json(cards::herz) == "herz");
-        CHECK(json(cards::karo) == "karo");
-
-        // json -> enum
-        CHECK(cards::kreuz == json("kreuz"));
-        CHECK(cards::pik == json("pik"));
-        CHECK(cards::herz == json("herz"));
-        CHECK(cards::karo == json("karo"));
-
-        // invalid json -> first enum
-        CHECK(cards::kreuz == json("what?").get<cards>());
-    }
-
-    SECTION("traditional enum")
-    {
-        // enum -> json
-        CHECK(json(TS_STOPPED) == "stopped");
-        CHECK(json(TS_RUNNING) == "running");
-        CHECK(json(TS_COMPLETED) == "completed");
-        CHECK(json(TS_INVALID) == json());
-
-        // json -> enum
-        CHECK(TS_STOPPED == json("stopped"));
-        CHECK(TS_RUNNING == json("running"));
-        CHECK(TS_COMPLETED == json("completed"));
-        CHECK(TS_INVALID == json());
-
-        // invalid json -> first enum
-        CHECK(TS_INVALID == json("what?").get<TaskState>());
-    }
-}
-
-enum class strict_cards {kreuz, pik, herz, karo, andere}; // andere not included in mapping
-
-// NOLINTNEXTLINE(misc-use-internal-linkage,misc-const-correctness) - false positive
-NLOHMANN_JSON_SERIALIZE_ENUM_STRICT(strict_cards,
-{
-    {strict_cards::kreuz, "kreuz"},
-    {strict_cards::pik, "pik"},
-    {strict_cards::pik, "puk"},  // second entry for cards::pik; will not be used
-    {strict_cards::herz, "herz"},
-    {strict_cards::karo, "karo"}
-})
-
-enum StrictTaskState // NOLINT(cert-int09-c,readability-enum-initial-value,cppcoreguidelines-use-enum-class)
-{
-    STRICT_TS_STOPPED,
-    STRICT_TS_RUNNING,
-    STRICT_TS_COMPLETED,
-    STRICT_TS_OTHER, // STRICT_TS_OTHER not in mapping
-    STRICT_TS_INVALID = -1,
-};
-
-// NOLINTNEXTLINE(misc-const-correctness,misc-use-internal-linkage) - false positive
-NLOHMANN_JSON_SERIALIZE_ENUM_STRICT(StrictTaskState,
-{
-    {STRICT_TS_INVALID, nullptr},
-    {STRICT_TS_STOPPED, "stopped"},
-    {STRICT_TS_RUNNING, "running"},
-    {STRICT_TS_COMPLETED, "completed"},
-})
-
-// regression test for #5708 item 2: NLOHMANN_JSON_SERIALIZE_ENUM_STRICT must not rely on
-// unqualified lookup of a helper name that a user's own namespace may also declare
-namespace ns_with_colliding_name
-{
-// NOLINTNEXTLINE(misc-use-internal-linkage) - used to shadow the library's internal helper name
-inline void templated_json_throw(int /*unused*/) {}
-
-enum class colliding_enum { a, b };
-
-// NOLINTNEXTLINE(misc-use-internal-linkage,misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays) - false positive
-NLOHMANN_JSON_SERIALIZE_ENUM_STRICT(colliding_enum,
-{
-    {colliding_enum::a, "a"},
-    {colliding_enum::b, "b"}
-})
-} // namespace ns_with_colliding_name
-
-TEST_CASE("NLOHMANN_JSON_SERIALIZE_ENUM_STRICT in a namespace with a colliding name")
-{
-    using ns_with_colliding_name::colliding_enum;
-
-    CHECK(json(colliding_enum::a) == "a");
-    CHECK(colliding_enum::b == json("b"));
-
-    json _;
-    CHECK_THROWS_WITH_AS(_ = json("nope").get<colliding_enum>(), "[json.exception.out_of_range.410] enum value out of range for colliding_enum: \"nope\"", json::out_of_range&);
-}
-
-TEST_CASE("Strict JSON to enum mapping")
-{
-    SECTION("enum class")
-    {
-        // enum -> json
-        CHECK(json(strict_cards::kreuz) == "kreuz");
-        CHECK(json(strict_cards::pik) == "pik");
-        CHECK(json(strict_cards::herz) == "herz");
-        CHECK(json(strict_cards::karo) == "karo");
-
-        // json -> enum
-        CHECK(json("kreuz").get<strict_cards>() == strict_cards::kreuz);
-        CHECK(json("pik").get<strict_cards>() == strict_cards::pik);
-        CHECK(json("herz").get<strict_cards>() == strict_cards::herz);
-        CHECK(json("karo").get<strict_cards>() == strict_cards::karo);
-
-        // comparison of enum and json
-        CHECK(strict_cards::kreuz == json("kreuz"));
-        CHECK(strict_cards::pik == json("pik"));
-        CHECK(strict_cards::herz == json("herz"));
-        CHECK(strict_cards::karo == json("karo"));
-
-        // invalid json -> exception thrown
-        json _;
-        CHECK_THROWS_WITH_AS(_ = json("what?").get<strict_cards>(), "[json.exception.out_of_range.410] enum value out of range for strict_cards: \"what?\"", json::out_of_range&);
-
-        // conversion of unmapped enum -> exception thrown
-        CHECK_THROWS_WITH_AS(json(strict_cards::andere), "[json.exception.out_of_range.410] enum value out of range for strict_cards", json::out_of_range&);
-
-        // comparing an unmapped enum with json throws the same exception
-        // (the scalar comparison operators used to be noexcept, so this
-        // called std::terminate)
-        CHECK_THROWS_WITH_AS(static_cast<void>(strict_cards::andere == json("andere")), "[json.exception.out_of_range.410] enum value out of range for strict_cards", json::out_of_range&);
-        CHECK_THROWS_WITH_AS(static_cast<void>(json("andere") != strict_cards::andere), "[json.exception.out_of_range.410] enum value out of range for strict_cards", json::out_of_range&);
-
-        // invalid UTF-8 -> out_of_range.410, not the type_error.316 thrown while building the
-        // message (regression test for #5667); such strings can reach get<Enum>() unvalidated,
-        // e.g. from from_cbor()/from_msgpack() (#5529)
-        const json j_invalid_utf8 = "\xFF";
-        CHECK_THROWS_WITH_AS(_ = j_invalid_utf8.get<strict_cards>(), "[json.exception.out_of_range.410] enum value out of range for strict_cards: \"\xEF\xBF\xBD\"", json::out_of_range&);
-    }
-
-    SECTION("traditional enum")
-    {
-        // enum -> json
-        CHECK(json(STRICT_TS_STOPPED) == "stopped");
-        CHECK(json(STRICT_TS_RUNNING) == "running");
-        CHECK(json(STRICT_TS_COMPLETED) == "completed");
-        CHECK(json(STRICT_TS_INVALID) == json());
-
-        // json -> enum
-        CHECK(json("stopped").get<StrictTaskState>() == STRICT_TS_STOPPED);
-        CHECK(json("running").get<StrictTaskState>() == STRICT_TS_RUNNING);
-        CHECK(json("completed").get<StrictTaskState>() == STRICT_TS_COMPLETED);
-        CHECK(json().get<StrictTaskState>() == STRICT_TS_INVALID);
-
-        // comparison of enum and json
-        CHECK(STRICT_TS_STOPPED == json("stopped"));
-        CHECK(STRICT_TS_RUNNING == json("running"));
-        CHECK(STRICT_TS_COMPLETED == json("completed"));
-        CHECK(STRICT_TS_INVALID == json());
-
-        // invalid json -> exception thrown
-        json _;
-        CHECK_THROWS_WITH_AS(_ = json("what?").get<StrictTaskState>(), "[json.exception.out_of_range.410] enum value out of range for StrictTaskState: \"what?\"", json::out_of_range&);
-
-        // conversion of unmapped enum -> exception thrown
-        CHECK_THROWS_WITH_AS(json(STRICT_TS_OTHER), "[json.exception.out_of_range.410] enum value out of range for StrictTaskState", json::out_of_range&);
-
-        // comparing an unmapped enum with json throws the same exception
-        CHECK_THROWS_WITH_AS(static_cast<void>(STRICT_TS_OTHER < json("x")), "[json.exception.out_of_range.410] enum value out of range for StrictTaskState", json::out_of_range&);
-    }
-}
-
-
-#ifdef JSON_HAS_CPP_17
-#if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
-TEST_CASE("std::filesystem::path")
-{
-    SECTION("ascii")
-    {
-        json const j_string = "Path";
-        auto p = j_string.template get<nlohmann::detail::std_fs::path>();
-        json const j_path = p;
-
-        CHECK(j_path.template get<std::string>() ==
-              j_string.template get<std::string>());
-    }
-
-    SECTION("utf-8")
-    {
-        json const j_string = "P\xc4\x9b\xc5\xa1ina";
-        auto p = j_string.template get<nlohmann::detail::std_fs::path>();
-        json const j_path = p;
-
-        CHECK(j_path.template get<std::string>() ==
-              j_string.template get<std::string>());
-    }
-}
-#endif
-
-// the ADL to_json overload for std::u8string only exists under the same guard
-// as std::filesystem::path support (it is otherwise only reached indirectly,
-// via std::filesystem::path::u8string()) -- mirror both #if conditions from
-// include/nlohmann/detail/conversions/to_json.hpp exactly
-#if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
-#if defined(__cpp_lib_char8_t)
-TEST_CASE("std::u8string")
-{
-    SECTION("ascii")
-    {
-        const std::u8string s = u8"Path";
-        json const j = s;
-
-        CHECK(j.template get<std::string>() == "Path");
-    }
-
-    SECTION("utf-8")
-    {
-        // use \u universal-character-names (rather than raw \x byte escapes
-        // or literal non-ASCII source bytes) to compose the multi-byte UTF-8
-        // encoding -- MSVC treats \x escapes used that way inside a u8
-        // literal as a nonstandard extension (warning C5321), which some of
-        // our CI configs promote to an error; \u is portable and produces
-        // the exact same encoded bytes without depending on the source
-        // file's encoding
-        const std::u8string s = u8"P\u011B\u0161ina";
-        json const j = s;
-
-        CHECK(j.template get<std::string>() == "P\xc4\x9b\xc5\xa1ina");
-    }
-}
-#endif
-#endif
-
-#if !defined(JSON_NOEXCEPTION)
-namespace
-{
-// a type whose to_json reports an error by throwing, used below to check that
-// converting a std::optional<T> to JSON propagates an exception thrown while
-// converting its contained value instead of calling std::terminate (#5642)
-struct throwing_to_json_type {};
-
-[[noreturn]] void to_json(json& /*unused*/, const throwing_to_json_type& /*unused*/)
-{
-    throw std::runtime_error("cannot serialize throwing_to_json_type");
-}
-}  // namespace
-#endif
-
-TEST_CASE("std::optional")
-{
-    SECTION("null")
-    {
-        const json j_null;
-        const std::optional<std::string> opt_null;
-
-        CHECK(json(opt_null) == j_null);
-        CHECK(j_null.get<std::optional<std::string>>() == std::nullopt);
-
-        // Constructing std::optional<T> directly from JSON null throws because
-        // std::optional's own converting constructor is chosen over basic_json's
-        // operator T(). This is a language-level limitation (std::optional<T> is
-        // constructible from T, and T is constructible from basic_json via the
-        // operator); there is no SFINAE path that distinguishes "call from inside
-        // std::optional's constructor" from "direct call". Use get<std::optional<T>>()
-        // or get_to() instead for correct null handling. See #4864 and #5246.
-        CHECK_THROWS_WITH_AS(std::optional<std::string>(j_null),
-                             "[json.exception.type_error.302] type must be string, but is null", json::type_error&);
-        CHECK_THROWS_WITH_AS(std::optional<int>(j_null),
-                             "[json.exception.type_error.302] type must be number, but is null", json::type_error&);
-
-        // Assignment goes through the same overload resolution as direct
-        // construction, so it throws for the same reason. This relies on
-        // basic_json's implicit conversion operator, so it only applies
-        // when JSON_USE_IMPLICIT_CONVERSIONS is enabled (the default).
-#if JSON_USE_IMPLICIT_CONVERSIONS
-        std::optional<std::string> opt_assign;
-        CHECK_THROWS_WITH_AS(opt_assign = j_null,
-                             "[json.exception.type_error.302] type must be string, but is null", json::type_error&);
-#endif
-
-        // get_to() is the correct way to obtain std::nullopt from a JSON null.
-        std::optional<std::string> opt_get_to = "placeholder";
-        j_null.get_to(opt_get_to);
-        CHECK(opt_get_to == std::nullopt);
-    }
-
-    SECTION("string")
-    {
-        json j_string = "string";
-        std::optional<std::string> opt_string = "string";
-
-        CHECK(json(opt_string) == j_string);
-        CHECK(std::optional<std::string>(j_string) == opt_string);
-        // false positive: Infer attributes the destruction of the temporaries above to opt_string
-        // @infer-ignore USE_AFTER_DELETE
-    }
-
-    SECTION("bool")
-    {
-        json j_bool = true;
-        std::optional<bool> opt_bool = true;
-
-        CHECK(json(opt_bool) == j_bool);
-        CHECK(std::optional<bool>(j_bool) == opt_bool);
-    }
-
-    SECTION("number")
-    {
-        json j_number = 1;
-        std::optional<int> opt_int = 1;
-
-        CHECK(json(opt_int) == j_number);
-        CHECK(j_number.get<std::optional<int>>() == opt_int);
-    }
-
-    SECTION("array")
-    {
-        json j_array = {1, 2, nullptr};
-        std::vector<std::optional<int>> opt_array = {{1, 2, std::nullopt}};
-
-        CHECK(json(opt_array) == j_array);
-        CHECK(j_array.get<std::vector<std::optional<int>>>() == opt_array);
-    }
-
-    SECTION("object")
-    {
-        json j_object = {{"one", 1}, {"two", 2}, {"zero", nullptr}};
-        std::map<std::string, std::optional<int>> opt_object {{"one", 1}, {"two", 2}, {"zero", std::nullopt}};
-
-        CHECK(json(opt_object) == j_object);
-        CHECK(std::map<std::string, std::optional<int>>(j_object) == opt_object);
-    }
-
-#if !defined(JSON_NOEXCEPTION)
-    SECTION("exception from contained value's to_json propagates (#5642)")
-    {
-        // to_json(BasicJsonType&, const std::optional<T>&) must not be
-        // noexcept: it calls T's to_json, which may throw (a user-defined
-        // to_json that reports an error, or std::bad_alloc for T =
-        // std::string/vector/json). Before the fix, this called
-        // std::terminate() instead of letting the exception propagate.
-        const std::optional<throwing_to_json_type> opt = throwing_to_json_type{};
-        CHECK_THROWS_WITH_AS(json(opt), "cannot serialize throwing_to_json_type", std::runtime_error&);
-
-        // the conversion is noexcept exactly when converting the contained value is
-        static_assert(!std::is_nothrow_constructible<json, const std::optional<throwing_to_json_type>&>::value);
-        static_assert(std::is_nothrow_constructible<json, const std::optional<int>&>::value);
-    }
-#endif
-}
-#endif
-
 #ifdef JSON_HAS_CPP_17
     #undef JSON_HAS_CPP_17
 #endif

tests/src/unit-conversions2.cpp

@@ -0,0 +1,868 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  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
+
+// cmake/test.cmake selects the C++ standard versions with which to build a
+// unit test based on the presence of JSON_HAS_CPP_<VERSION> macros.
+// When using macros that are only defined for particular versions of the standard
+// (e.g., JSON_HAS_FILESYSTEM for C++17 and up), please mention the corresponding
+// version macro in a comment close by, like this:
+// JSON_HAS_CPP_<VERSION> (do not remove; see note at top of file)
+
+#include "doctest_compatibility.h"
+
+// skip tests if JSON_DisableEnumSerialization=ON (#4384)
+#if defined(JSON_DISABLE_ENUM_SERIALIZATION) && (JSON_DISABLE_ENUM_SERIALIZATION == 1)
+    #define SKIP_TESTS_FOR_ENUM_SERIALIZATION
+#endif
+
+#define JSON_TESTS_PRIVATE
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <deque>
+#include <forward_list>
+#include <list>
+#include <set>
+#include <unordered_map>
+#include <unordered_set>
+#include <valarray>
+
+// NLOHMANN_JSON_SERIALIZE_ENUM uses a static std::pair
+DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
+DOCTEST_CLANG_SUPPRESS_WARNING("-Wexit-time-destructors")
+
+#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
+    #define JSON_HAS_CPP_17
+    #define JSON_HAS_CPP_14
+#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
+    #define JSON_HAS_CPP_14
+#endif
+
+#ifdef JSON_HAS_CPP_17
+    #if __has_include(<optional>)
+        #include <optional>
+    #elif __has_include(<experimental/optional>)
+        #include <experimental/optional>
+    #endif
+#endif
+
+#if defined(JSON_HAS_CPP_17)
+    #include <string_view>
+#endif
+
+TEST_CASE("value conversion")
+{
+    SECTION("get a binary value (explicit)")
+    {
+        json::binary_t const n_reference{{1, 2, 3}};
+        json j(n_reference);
+
+        SECTION("binary_t")
+        {
+            json::binary_t const b = j.get<json::binary_t>();
+            CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
+        }
+
+        SECTION("get_binary()")
+        {
+            SECTION("non-const")
+            {
+                auto& b = j.get_binary();
+                CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
+            }
+
+            SECTION("non-const")
+            {
+                const json j_const = j; // NOLINT(performance-unnecessary-copy-initialization)
+                const auto& b = j_const.get_binary();
+                CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
+            }
+        }
+
+        SECTION("exception in case of a non-string type")
+        {
+            json j_null(json::value_t::null);
+            json j_object(json::value_t::object);
+            json j_array(json::value_t::array);
+            json j_string(json::value_t::string);
+            json j_boolean(json::value_t::boolean);
+            const json j_null_const(json::value_t::null);
+            const json j_object_const(json::value_t::object);
+            const json j_array_const(json::value_t::array);
+            const json j_string_const(json::value_t::string);
+            const json j_boolean_const(json::value_t::boolean);
+
+            CHECK_THROWS_WITH_AS(j_null.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is null",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_object.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is object",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_array.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is array",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_string.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is string",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_boolean.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is boolean",
+                                 json::type_error&);
+
+            CHECK_THROWS_WITH_AS(j_null_const.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is null",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_object_const.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is object",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_array_const.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is array",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_string_const.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is string",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_boolean_const.get<json::binary_t>(),
+                                 "[json.exception.type_error.302] type must be binary, but is boolean",
+                                 json::type_error&);
+
+            CHECK_THROWS_WITH_AS(j_null.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is null",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_object.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is object",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_array.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is array",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_string.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is string",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_boolean.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is boolean",
+                                 json::type_error&);
+
+            CHECK_THROWS_WITH_AS(j_null_const.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is null",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_object_const.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is object",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_array_const.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is array",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_string_const.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is string",
+                                 json::type_error&);
+            CHECK_THROWS_WITH_AS(j_boolean_const.get_binary(),
+                                 "[json.exception.type_error.302] type must be binary, but is boolean",
+                                 json::type_error&);
+        }
+    }
+
+#if JSON_USE_IMPLICIT_CONVERSIONS
+    SECTION("get a binary value (implicit)")
+    {
+        json::binary_t const n_reference{{1, 2, 3}};
+        json const j(n_reference);
+
+        SECTION("binary_t")
+        {
+            json::binary_t const b = j;
+            CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
+        }
+    }
+#endif
+
+#ifndef SKIP_TESTS_FOR_ENUM_SERIALIZATION
+    SECTION("get an enum")
+    {
+        enum c_enum { value_1, value_2 }; // NOLINT(cppcoreguidelines-use-enum-class)
+        enum class cpp_enum { value_1, value_2 };
+
+        CHECK(json(value_1).get<c_enum>() == value_1);
+        CHECK(json(cpp_enum::value_1).get<cpp_enum>() == cpp_enum::value_1);
+    }
+
+    SECTION("get an enum with underlying type bool (#5671)")
+    {
+        enum class bool_enum : bool { off, on };
+
+        CHECK(json(bool_enum::off).get<bool_enum>() == bool_enum::off);
+        CHECK(json(bool_enum::on).get<bool_enum>() == bool_enum::on);
+    }
+#endif
+
+    SECTION("more involved conversions")
+    {
+        SECTION("object-like STL containers")
+        {
+            json const j1 = {{"one", 1}, {"two", 2}, {"three", 3}};
+            json const j2 = {{"one", 1u}, {"two", 2u}, {"three", 3u}};
+            json const j3 = {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}};
+            json const j4 = {{"one", true}, {"two", false}, {"three", true}};
+            json const j5 = {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}};
+
+            SECTION("std::map")
+            {
+                CHECK(j1.get<std::map<std::string, int>>() == (std::map<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
+                CHECK(j2.get<std::map<std::string, unsigned int>>() == (std::map<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
+                CHECK(j3.get<std::map<std::string, double>>() == (std::map<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
+                CHECK(j4.get<std::map<std::string, bool>>() == (std::map<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
+                CHECK(j5.get<std::map<std::string, std::string>>() == (std::map<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
+            }
+
+            SECTION("std::unordered_map")
+            {
+                CHECK(j1.get<std::unordered_map<std::string, int>>() == (std::unordered_map<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
+                CHECK(j2.get<std::unordered_map<std::string, unsigned int>>() == (std::unordered_map<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
+                CHECK(j3.get<std::unordered_map<std::string, double>>() == (std::unordered_map<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
+                CHECK(j4.get<std::unordered_map<std::string, bool>>() == (std::unordered_map<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
+                const auto m5 = j5.get<std::unordered_map<std::string, std::string>>();
+                CHECK(m5 == (std::unordered_map<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
+                CHECK(m5.at("one") == "eins");
+            }
+
+            SECTION("reserve is called on containers that support it (#5406)")
+            {
+                // build a larger object so that a missing/incorrect reserve()
+                // call would be more likely to corrupt or drop elements
+                json j_large;
+                for (int i = 0; i < 100; ++i)
+                {
+                    j_large[std::to_string(i)] = i;
+                }
+
+                SECTION("std::unordered_map (supports reserve)")
+                {
+                    const auto m = j_large.get<std::unordered_map<std::string, int>>();
+                    CHECK(m.size() == 100);
+                    for (int i = 0; i < 100; ++i)
+                    {
+                        CHECK(m.at(std::to_string(i)) == i);
+                    }
+                }
+
+                SECTION("std::map (no reserve, fallback path)")
+                {
+                    const auto m = j_large.get<std::map<std::string, int>>();
+                    CHECK(m.size() == 100);
+                    for (int i = 0; i < 100; ++i)
+                    {
+                        CHECK(m.at(std::to_string(i)) == i);
+                    }
+                }
+            }
+
+            SECTION("std::multimap")
+            {
+                CHECK(j1.get<std::multimap<std::string, int>>() == (std::multimap<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
+                CHECK(j2.get<std::multimap<std::string, unsigned int>>() == (std::multimap<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
+                CHECK(j3.get<std::multimap<std::string, double>>() == (std::multimap<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
+                CHECK(j4.get<std::multimap<std::string, bool>>() == (std::multimap<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
+                const auto m5 = j5.get<std::multimap<std::string, std::string>>();
+                CHECK(m5 == (std::multimap<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
+                CHECK(m5.find("one")->second == "eins");
+            }
+
+            SECTION("std::unordered_multimap")
+            {
+                CHECK(j1.get<std::unordered_multimap<std::string, int>>() == (std::unordered_multimap<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
+                CHECK(j2.get<std::unordered_multimap<std::string, unsigned int>>() == (std::unordered_multimap<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
+                CHECK(j3.get<std::unordered_multimap<std::string, double>>() == (std::unordered_multimap<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
+                CHECK(j4.get<std::unordered_multimap<std::string, bool>>() == (std::unordered_multimap<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
+                const auto m5 = j5.get<std::unordered_multimap<std::string, std::string>>();
+                CHECK(m5 == (std::unordered_multimap<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
+                CHECK(m5.find("one")->second == "eins");
+            }
+
+            SECTION("exception in case of a non-object type")
+            {
+                CHECK_THROWS_WITH_AS(
+                    (json().get<std::map<std::string, int>>()),
+                    "[json.exception.type_error.302] type must be object, but is null", json::type_error&);
+            }
+        }
+
+        SECTION("array-like STL containers")
+        {
+            json const j1 = {1, 2, 3, 4};
+            json const j2 = {1u, 2u, 3u, 4u};
+            json const j3 = {1.2, 2.3, 3.4, 4.5};
+            json const j4 = {true, false, true};
+            json const j5 = {"one", "two", "three"};
+
+            SECTION("std::list")
+            {
+                CHECK(j1.get<std::list<int>>() == (std::list<int> {1, 2, 3, 4}));
+                CHECK(j2.get<std::list<unsigned int>>() == (std::list<unsigned int> {1u, 2u, 3u, 4u}));
+                CHECK(j3.get<std::list<double>>() == (std::list<double> {1.2, 2.3, 3.4, 4.5}));
+                CHECK(j4.get<std::list<bool>>() == (std::list<bool> {true, false, true}));
+                CHECK(j5.get<std::list<std::string>>() == (std::list<std::string> {"one", "two", "three"}));
+            }
+
+            SECTION("std::forward_list")
+            {
+                CHECK(j1.get<std::forward_list<int>>() == (std::forward_list<int> {1, 2, 3, 4}));
+                CHECK(j2.get<std::forward_list<unsigned int>>() == (std::forward_list<unsigned int> {1u, 2u, 3u, 4u}));
+                CHECK(j3.get<std::forward_list<double>>() == (std::forward_list<double> {1.2, 2.3, 3.4, 4.5}));
+                CHECK(j4.get<std::forward_list<bool>>() == (std::forward_list<bool> {true, false, true}));
+                CHECK(j5.get<std::forward_list<std::string>>() == (std::forward_list<std::string> {"one", "two", "three"}));
+            }
+
+            SECTION("std::array")
+            {
+                CHECK(j1.get<std::array<int, 4>>() == (std::array<int, 4> {{1, 2, 3, 4}}));
+                // only the first 3 elements of j2 are converted, since the target array is smaller
+                CHECK(j2.get<std::array<unsigned int, 3>>() == (std::array<unsigned int, 3> {{1u, 2u, 3u}}));
+                CHECK(j3.get<std::array<double, 4>>() == (std::array<double, 4> {{1.2, 2.3, 3.4, 4.5}}));
+                CHECK(j4.get<std::array<bool, 3>>() == (std::array<bool, 3> {{true, false, true}}));
+                CHECK(j5.get<std::array<std::string, 3>>() == (std::array<std::string, 3> {{"one", "two", "three"}}));
+
+                SECTION("std::array is larger than JSON")
+                {
+                    std::array<int, 6> arr6 = {{1, 2, 3, 4, 5, 6}};
+                    CHECK_THROWS_WITH_AS(j1.get_to(arr6), "[json.exception.out_of_range.401] "
+                                         "array index 4 is out of range", json::out_of_range&);
+                }
+
+                SECTION("std::array is smaller than JSON")
+                {
+                    std::array<int, 2> arr2 = {{8, 9}};
+                    j1.get_to(arr2);
+                    CHECK(arr2[0] == 1);
+                    CHECK(arr2[1] == 2);
+                }
+            }
+
+            SECTION("std::valarray")
+            {
+                // valarray has no operator== that returns bool, so compare via a vector copy
+                const auto v1 = j1.get<std::valarray<int>>();
+                CHECK((std::vector<int>(std::begin(v1), std::end(v1)) == std::vector<int> {1, 2, 3, 4}));
+                const auto v2 = j2.get<std::valarray<unsigned int>>();
+                CHECK((std::vector<unsigned int>(std::begin(v2), std::end(v2)) == std::vector<unsigned int> {1u, 2u, 3u, 4u}));
+                const auto v3 = j3.get<std::valarray<double>>();
+                CHECK((std::vector<double>(std::begin(v3), std::end(v3)) == std::vector<double> {1.2, 2.3, 3.4, 4.5}));
+                const auto v4 = j4.get<std::valarray<bool>>();
+                CHECK((std::vector<bool>(std::begin(v4), std::end(v4)) == std::vector<bool> {true, false, true}));
+                const auto v5 = j5.get<std::valarray<std::string>>();
+                CHECK((std::vector<std::string>(std::begin(v5), std::end(v5)) == std::vector<std::string> {"one", "two", "three"}));
+            }
+
+            SECTION("std::vector")
+            {
+                CHECK(j1.get<std::vector<int>>() == (std::vector<int> {1, 2, 3, 4}));
+                CHECK(j2.get<std::vector<unsigned int>>() == (std::vector<unsigned int> {1u, 2u, 3u, 4u}));
+                CHECK(j3.get<std::vector<double>>() == (std::vector<double> {1.2, 2.3, 3.4, 4.5}));
+                CHECK(j4.get<std::vector<bool>>() == (std::vector<bool> {true, false, true}));
+                CHECK(j5.get<std::vector<std::string>>() == (std::vector<std::string> {"one", "two", "three"}));
+            }
+
+            SECTION("std::deque")
+            {
+                CHECK(j1.get<std::deque<int>>() == (std::deque<int> {1, 2, 3, 4}));
+                CHECK(j2.get<std::deque<unsigned int>>() == (std::deque<unsigned int> {1u, 2u, 3u, 4u}));
+                CHECK(j3.get<std::deque<double>>() == (std::deque<double> {1.2, 2.3, 3.4, 4.5}));
+                CHECK(j4.get<std::deque<bool>>() == (std::deque<bool> {true, false, true}));
+                CHECK(j5.get<std::deque<std::string>>() == (std::deque<std::string> {"one", "two", "three"}));
+            }
+
+            SECTION("std::set")
+            {
+                CHECK(j1.get<std::set<int>>() == (std::set<int> {1, 2, 3, 4}));
+                CHECK(j2.get<std::set<unsigned int>>() == (std::set<unsigned int> {1u, 2u, 3u, 4u}));
+                CHECK(j3.get<std::set<double>>() == (std::set<double> {1.2, 2.3, 3.4, 4.5}));
+                CHECK(j4.get<std::set<bool>>() == (std::set<bool> {true, false, true}));
+                CHECK(j5.get<std::set<std::string>>() == (std::set<std::string> {"one", "two", "three"}));
+            }
+
+            SECTION("std::unordered_set")
+            {
+                CHECK(j1.get<std::unordered_set<int>>() == (std::unordered_set<int> {1, 2, 3, 4}));
+                CHECK(j2.get<std::unordered_set<unsigned int>>() == (std::unordered_set<unsigned int> {1u, 2u, 3u, 4u}));
+                CHECK(j3.get<std::unordered_set<double>>() == (std::unordered_set<double> {1.2, 2.3, 3.4, 4.5}));
+                CHECK(j4.get<std::unordered_set<bool>>() == (std::unordered_set<bool> {true, false, true}));
+                CHECK(j5.get<std::unordered_set<std::string>>() == (std::unordered_set<std::string> {"one", "two", "three"}));
+            }
+
+            SECTION("std::map (array of pairs)")
+            {
+                const std::map<int, int> m{{0, 1}, {1, 2}, {2, 3}};
+                json const j6 = m;
+
+                auto m2 = j6.get<std::map<int, int>>();
+                CHECK(m == m2);
+
+                json const j7 = {0, 1, 2, 3};
+                json const j8 = 2;
+#if JSON_DIAGNOSTICS
+                CHECK_THROWS_WITH_AS((j7.get<std::map<int, int>>()),
+                                     "[json.exception.type_error.302] (/0) type must be array, "
+                                     "but is number", json::type_error&);
+#else
+                CHECK_THROWS_WITH_AS((j7.get<std::map<int, int>>()),
+                                     "[json.exception.type_error.302] type must be array, "
+                                     "but is number", json::type_error&);
+#endif
+                CHECK_THROWS_WITH_AS((j8.get<std::map<int, int>>()),
+                                     "[json.exception.type_error.302] type must be array, "
+                                     "but is number", json::type_error&);
+
+                SECTION("superfluous entries")
+                {
+                    json const j9 = {{0, 1, 2}, {1, 2, 3}, {2, 3, 4}};
+                    m2 = j9.get<std::map<int, int>>();
+                    CHECK(m == m2);
+                }
+            }
+
+            SECTION("std::unordered_map (array of pairs)")
+            {
+                const std::unordered_map<int, int> m{{0, 1}, {1, 2}, {2, 3}};
+                json const j6 = m;
+
+                auto m2 = j6.get<std::unordered_map<int, int>>();
+                CHECK(m == m2);
+
+                json const j7 = {0, 1, 2, 3};
+                json const j8 = 2;
+#if JSON_DIAGNOSTICS
+                CHECK_THROWS_WITH_AS((j7.get<std::unordered_map<int, int>>()),
+                                     "[json.exception.type_error.302] (/0) type must be array, "
+                                     "but is number", json::type_error&);
+#else
+                CHECK_THROWS_WITH_AS((j7.get<std::unordered_map<int, int>>()),
+                                     "[json.exception.type_error.302] type must be array, "
+                                     "but is number", json::type_error&);
+#endif
+                CHECK_THROWS_WITH_AS((j8.get<std::unordered_map<int, int>>()),
+                                     "[json.exception.type_error.302] type must be array, "
+                                     "but is number", json::type_error&);
+
+                SECTION("superfluous entries")
+                {
+                    json const j9{{0, 1, 2}, {1, 2, 3}, {2, 3, 4}};
+                    m2 = j9.get<std::unordered_map<int, int>>();
+                    CHECK(m == m2);
+                }
+            }
+
+            SECTION("exception in case of a non-object type")
+            {
+                // does type really must be an array? or it rather must not be null?
+                // that's what I thought when other test like this one broke
+                CHECK_THROWS_WITH_AS(
+                    (json().get<std::list<int>>()),
+                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
+                CHECK_THROWS_WITH_AS(
+                    (json().get<std::vector<int>>()),
+                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
+                CHECK_THROWS_WITH_AS(
+                    (json().get<std::vector<json>>()),
+                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
+                CHECK_THROWS_WITH_AS(
+                    (json().get<std::list<json>>()),
+                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
+                CHECK_THROWS_WITH_AS(
+                    (json().get<std::valarray<int>>()),
+                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
+                CHECK_THROWS_WITH_AS(
+                    (json().get<std::map<int, int>>()),
+                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
+            }
+        }
+    }
+}
+
+enum class cards {kreuz, pik, herz, karo};
+
+// NOLINTNEXTLINE(misc-use-internal-linkage,misc-const-correctness) - false positive
+NLOHMANN_JSON_SERIALIZE_ENUM(cards,
+{
+    {cards::kreuz, "kreuz"},
+    {cards::pik, "pik"},
+    {cards::pik, "puk"},  // second entry for cards::puk; will not be used
+    {cards::herz, "herz"},
+    {cards::karo, "karo"}
+})
+
+enum TaskState // NOLINT(cert-int09-c,readability-enum-initial-value,cppcoreguidelines-use-enum-class)
+{
+    TS_STOPPED,
+    TS_RUNNING,
+    TS_COMPLETED,
+    TS_INVALID = -1,
+};
+
+// NOLINTNEXTLINE(misc-const-correctness,misc-use-internal-linkage) - false positive
+NLOHMANN_JSON_SERIALIZE_ENUM(TaskState,
+{
+    {TS_INVALID, nullptr},
+    {TS_STOPPED, "stopped"},
+    {TS_RUNNING, "running"},
+    {TS_COMPLETED, "completed"},
+})
+
+TEST_CASE("JSON to enum mapping")
+{
+    SECTION("enum class")
+    {
+        // enum -> json
+        CHECK(json(cards::kreuz) == "kreuz");
+        CHECK(json(cards::pik) == "pik");
+        CHECK(json(cards::herz) == "herz");
+        CHECK(json(cards::karo) == "karo");
+
+        // json -> enum
+        CHECK(cards::kreuz == json("kreuz"));
+        CHECK(cards::pik == json("pik"));
+        CHECK(cards::herz == json("herz"));
+        CHECK(cards::karo == json("karo"));
+
+        // invalid json -> first enum
+        CHECK(cards::kreuz == json("what?").get<cards>());
+    }
+
+    SECTION("traditional enum")
+    {
+        // enum -> json
+        CHECK(json(TS_STOPPED) == "stopped");
+        CHECK(json(TS_RUNNING) == "running");
+        CHECK(json(TS_COMPLETED) == "completed");
+        CHECK(json(TS_INVALID) == json());
+
+        // json -> enum
+        CHECK(TS_STOPPED == json("stopped"));
+        CHECK(TS_RUNNING == json("running"));
+        CHECK(TS_COMPLETED == json("completed"));
+        CHECK(TS_INVALID == json());
+
+        // invalid json -> first enum
+        CHECK(TS_INVALID == json("what?").get<TaskState>());
+    }
+}
+
+enum class strict_cards {kreuz, pik, herz, karo, andere}; // andere not included in mapping
+
+// NOLINTNEXTLINE(misc-use-internal-linkage,misc-const-correctness) - false positive
+NLOHMANN_JSON_SERIALIZE_ENUM_STRICT(strict_cards,
+{
+    {strict_cards::kreuz, "kreuz"},
+    {strict_cards::pik, "pik"},
+    {strict_cards::pik, "puk"},  // second entry for cards::pik; will not be used
+    {strict_cards::herz, "herz"},
+    {strict_cards::karo, "karo"}
+})
+
+enum StrictTaskState // NOLINT(cert-int09-c,readability-enum-initial-value,cppcoreguidelines-use-enum-class)
+{
+    STRICT_TS_STOPPED,
+    STRICT_TS_RUNNING,
+    STRICT_TS_COMPLETED,
+    STRICT_TS_OTHER, // STRICT_TS_OTHER not in mapping
+    STRICT_TS_INVALID = -1,
+};
+
+// NOLINTNEXTLINE(misc-const-correctness,misc-use-internal-linkage) - false positive
+NLOHMANN_JSON_SERIALIZE_ENUM_STRICT(StrictTaskState,
+{
+    {STRICT_TS_INVALID, nullptr},
+    {STRICT_TS_STOPPED, "stopped"},
+    {STRICT_TS_RUNNING, "running"},
+    {STRICT_TS_COMPLETED, "completed"},
+})
+
+// regression test for #5708 item 2: NLOHMANN_JSON_SERIALIZE_ENUM_STRICT must not rely on
+// unqualified lookup of a helper name that a user's own namespace may also declare
+namespace ns_with_colliding_name
+{
+// NOLINTNEXTLINE(misc-use-internal-linkage) - used to shadow the library's internal helper name
+inline void templated_json_throw(int /*unused*/) {}
+
+enum class colliding_enum { a, b };
+
+// NOLINTNEXTLINE(misc-use-internal-linkage,misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays) - false positive
+NLOHMANN_JSON_SERIALIZE_ENUM_STRICT(colliding_enum,
+{
+    {colliding_enum::a, "a"},
+    {colliding_enum::b, "b"}
+})
+} // namespace ns_with_colliding_name
+
+TEST_CASE("NLOHMANN_JSON_SERIALIZE_ENUM_STRICT in a namespace with a colliding name")
+{
+    using ns_with_colliding_name::colliding_enum;
+
+    CHECK(json(colliding_enum::a) == "a");
+    CHECK(colliding_enum::b == json("b"));
+
+    json _;
+    CHECK_THROWS_WITH_AS(_ = json("nope").get<colliding_enum>(), "[json.exception.out_of_range.410] enum value out of range for colliding_enum: \"nope\"", json::out_of_range&);
+}
+
+TEST_CASE("Strict JSON to enum mapping")
+{
+    SECTION("enum class")
+    {
+        // enum -> json
+        CHECK(json(strict_cards::kreuz) == "kreuz");
+        CHECK(json(strict_cards::pik) == "pik");
+        CHECK(json(strict_cards::herz) == "herz");
+        CHECK(json(strict_cards::karo) == "karo");
+
+        // json -> enum
+        CHECK(json("kreuz").get<strict_cards>() == strict_cards::kreuz);
+        CHECK(json("pik").get<strict_cards>() == strict_cards::pik);
+        CHECK(json("herz").get<strict_cards>() == strict_cards::herz);
+        CHECK(json("karo").get<strict_cards>() == strict_cards::karo);
+
+        // comparison of enum and json
+        CHECK(strict_cards::kreuz == json("kreuz"));
+        CHECK(strict_cards::pik == json("pik"));
+        CHECK(strict_cards::herz == json("herz"));
+        CHECK(strict_cards::karo == json("karo"));
+
+        // invalid json -> exception thrown
+        json _;
+        CHECK_THROWS_WITH_AS(_ = json("what?").get<strict_cards>(), "[json.exception.out_of_range.410] enum value out of range for strict_cards: \"what?\"", json::out_of_range&);
+
+        // conversion of unmapped enum -> exception thrown
+        CHECK_THROWS_WITH_AS(json(strict_cards::andere), "[json.exception.out_of_range.410] enum value out of range for strict_cards", json::out_of_range&);
+
+        // comparing an unmapped enum with json throws the same exception
+        // (the scalar comparison operators used to be noexcept, so this
+        // called std::terminate)
+        CHECK_THROWS_WITH_AS(static_cast<void>(strict_cards::andere == json("andere")), "[json.exception.out_of_range.410] enum value out of range for strict_cards", json::out_of_range&);
+        CHECK_THROWS_WITH_AS(static_cast<void>(json("andere") != strict_cards::andere), "[json.exception.out_of_range.410] enum value out of range for strict_cards", json::out_of_range&);
+
+        // invalid UTF-8 -> out_of_range.410, not the type_error.316 thrown while building the
+        // message (regression test for #5667); such strings can reach get<Enum>() unvalidated,
+        // e.g. from from_cbor()/from_msgpack() (#5529)
+        const json j_invalid_utf8 = "\xFF";
+        CHECK_THROWS_WITH_AS(_ = j_invalid_utf8.get<strict_cards>(), "[json.exception.out_of_range.410] enum value out of range for strict_cards: \"\xEF\xBF\xBD\"", json::out_of_range&);
+    }
+
+    SECTION("traditional enum")
+    {
+        // enum -> json
+        CHECK(json(STRICT_TS_STOPPED) == "stopped");
+        CHECK(json(STRICT_TS_RUNNING) == "running");
+        CHECK(json(STRICT_TS_COMPLETED) == "completed");
+        CHECK(json(STRICT_TS_INVALID) == json());
+
+        // json -> enum
+        CHECK(json("stopped").get<StrictTaskState>() == STRICT_TS_STOPPED);
+        CHECK(json("running").get<StrictTaskState>() == STRICT_TS_RUNNING);
+        CHECK(json("completed").get<StrictTaskState>() == STRICT_TS_COMPLETED);
+        CHECK(json().get<StrictTaskState>() == STRICT_TS_INVALID);
+
+        // comparison of enum and json
+        CHECK(STRICT_TS_STOPPED == json("stopped"));
+        CHECK(STRICT_TS_RUNNING == json("running"));
+        CHECK(STRICT_TS_COMPLETED == json("completed"));
+        CHECK(STRICT_TS_INVALID == json());
+
+        // invalid json -> exception thrown
+        json _;
+        CHECK_THROWS_WITH_AS(_ = json("what?").get<StrictTaskState>(), "[json.exception.out_of_range.410] enum value out of range for StrictTaskState: \"what?\"", json::out_of_range&);
+
+        // conversion of unmapped enum -> exception thrown
+        CHECK_THROWS_WITH_AS(json(STRICT_TS_OTHER), "[json.exception.out_of_range.410] enum value out of range for StrictTaskState", json::out_of_range&);
+
+        // comparing an unmapped enum with json throws the same exception
+        CHECK_THROWS_WITH_AS(static_cast<void>(STRICT_TS_OTHER < json("x")), "[json.exception.out_of_range.410] enum value out of range for StrictTaskState", json::out_of_range&);
+    }
+}
+
+
+#ifdef JSON_HAS_CPP_17
+#if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
+TEST_CASE("std::filesystem::path")
+{
+    SECTION("ascii")
+    {
+        json const j_string = "Path";
+        auto p = j_string.template get<nlohmann::detail::std_fs::path>();
+        json const j_path = p;
+
+        CHECK(j_path.template get<std::string>() ==
+              j_string.template get<std::string>());
+    }
+
+    SECTION("utf-8")
+    {
+        json const j_string = "P\xc4\x9b\xc5\xa1ina";
+        auto p = j_string.template get<nlohmann::detail::std_fs::path>();
+        json const j_path = p;
+
+        CHECK(j_path.template get<std::string>() ==
+              j_string.template get<std::string>());
+    }
+}
+#endif
+
+// the ADL to_json overload for std::u8string only exists under the same guard
+// as std::filesystem::path support (it is otherwise only reached indirectly,
+// via std::filesystem::path::u8string()) -- mirror both #if conditions from
+// include/nlohmann/detail/conversions/to_json.hpp exactly
+#if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
+#if defined(__cpp_lib_char8_t)
+TEST_CASE("std::u8string")
+{
+    SECTION("ascii")
+    {
+        const std::u8string s = u8"Path";
+        json const j = s;
+
+        CHECK(j.template get<std::string>() == "Path");
+    }
+
+    SECTION("utf-8")
+    {
+        // use \u universal-character-names (rather than raw \x byte escapes
+        // or literal non-ASCII source bytes) to compose the multi-byte UTF-8
+        // encoding -- MSVC treats \x escapes used that way inside a u8
+        // literal as a nonstandard extension (warning C5321), which some of
+        // our CI configs promote to an error; \u is portable and produces
+        // the exact same encoded bytes without depending on the source
+        // file's encoding
+        const std::u8string s = u8"P\u011B\u0161ina";
+        json const j = s;
+
+        CHECK(j.template get<std::string>() == "P\xc4\x9b\xc5\xa1ina");
+    }
+}
+#endif
+#endif
+
+#if !defined(JSON_NOEXCEPTION)
+namespace
+{
+// a type whose to_json reports an error by throwing, used below to check that
+// converting a std::optional<T> to JSON propagates an exception thrown while
+// converting its contained value instead of calling std::terminate (#5642)
+struct throwing_to_json_type {};
+
+[[noreturn]] void to_json(json& /*unused*/, const throwing_to_json_type& /*unused*/)
+{
+    throw std::runtime_error("cannot serialize throwing_to_json_type");
+}
+}  // namespace
+#endif
+
+TEST_CASE("std::optional")
+{
+    SECTION("null")
+    {
+        const json j_null;
+        const std::optional<std::string> opt_null;
+
+        CHECK(json(opt_null) == j_null);
+        CHECK(j_null.get<std::optional<std::string>>() == std::nullopt);
+
+        // Constructing std::optional<T> directly from JSON null throws because
+        // std::optional's own converting constructor is chosen over basic_json's
+        // operator T(). This is a language-level limitation (std::optional<T> is
+        // constructible from T, and T is constructible from basic_json via the
+        // operator); there is no SFINAE path that distinguishes "call from inside
+        // std::optional's constructor" from "direct call". Use get<std::optional<T>>()
+        // or get_to() instead for correct null handling. See #4864 and #5246.
+        CHECK_THROWS_WITH_AS(std::optional<std::string>(j_null),
+                             "[json.exception.type_error.302] type must be string, but is null", json::type_error&);
+        CHECK_THROWS_WITH_AS(std::optional<int>(j_null),
+                             "[json.exception.type_error.302] type must be number, but is null", json::type_error&);
+
+        // Assignment goes through the same overload resolution as direct
+        // construction, so it throws for the same reason. This relies on
+        // basic_json's implicit conversion operator, so it only applies
+        // when JSON_USE_IMPLICIT_CONVERSIONS is enabled (the default).
+#if JSON_USE_IMPLICIT_CONVERSIONS
+        std::optional<std::string> opt_assign;
+        CHECK_THROWS_WITH_AS(opt_assign = j_null,
+                             "[json.exception.type_error.302] type must be string, but is null", json::type_error&);
+#endif
+
+        // get_to() is the correct way to obtain std::nullopt from a JSON null.
+        std::optional<std::string> opt_get_to = "placeholder";
+        j_null.get_to(opt_get_to);
+        CHECK(opt_get_to == std::nullopt);
+    }
+
+    SECTION("string")
+    {
+        json j_string = "string";
+        std::optional<std::string> opt_string = "string";
+
+        CHECK(json(opt_string) == j_string);
+        CHECK(std::optional<std::string>(j_string) == opt_string);
+        // false positive: Infer attributes the destruction of the temporaries above to opt_string
+        // @infer-ignore USE_AFTER_DELETE
+    }
+
+    SECTION("bool")
+    {
+        json j_bool = true;
+        std::optional<bool> opt_bool = true;
+
+        CHECK(json(opt_bool) == j_bool);
+        CHECK(std::optional<bool>(j_bool) == opt_bool);
+    }
+
+    SECTION("number")
+    {
+        json j_number = 1;
+        std::optional<int> opt_int = 1;
+
+        CHECK(json(opt_int) == j_number);
+        CHECK(j_number.get<std::optional<int>>() == opt_int);
+    }
+
+    SECTION("array")
+    {
+        json j_array = {1, 2, nullptr};
+        std::vector<std::optional<int>> opt_array = {{1, 2, std::nullopt}};
+
+        CHECK(json(opt_array) == j_array);
+        CHECK(j_array.get<std::vector<std::optional<int>>>() == opt_array);
+    }
+
+    SECTION("object")
+    {
+        json j_object = {{"one", 1}, {"two", 2}, {"zero", nullptr}};
+        std::map<std::string, std::optional<int>> opt_object {{"one", 1}, {"two", 2}, {"zero", std::nullopt}};
+
+        CHECK(json(opt_object) == j_object);
+        CHECK(std::map<std::string, std::optional<int>>(j_object) == opt_object);
+    }
+
+#if !defined(JSON_NOEXCEPTION)
+    SECTION("exception from contained value's to_json propagates (#5642)")
+    {
+        // to_json(BasicJsonType&, const std::optional<T>&) must not be
+        // noexcept: it calls T's to_json, which may throw (a user-defined
+        // to_json that reports an error, or std::bad_alloc for T =
+        // std::string/vector/json). Before the fix, this called
+        // std::terminate() instead of letting the exception propagate.
+        const std::optional<throwing_to_json_type> opt = throwing_to_json_type{};
+        CHECK_THROWS_WITH_AS(json(opt), "cannot serialize throwing_to_json_type", std::runtime_error&);
+
+        // the conversion is noexcept exactly when converting the contained value is
+        static_assert(!std::is_nothrow_constructible<json, const std::optional<throwing_to_json_type>&>::value);
+        static_assert(std::is_nothrow_constructible<json, const std::optional<int>&>::value);
+    }
+#endif
+}
+#endif
+
+#ifdef JSON_HAS_CPP_17
+    #undef JSON_HAS_CPP_17
+#endif
+
+#ifdef JSON_HAS_CPP_14
+    #undef JSON_HAS_CPP_14
+#endif
+DOCTEST_CLANG_SUPPRESS_WARNING_POP

tests/src/unit-custom-base-class.cpp

@@ -505,7 +505,7 @@ static json_with_const_base make_nested_array(std::size_t depth)
 {
     if (depth == 0)
     {
-        return json_with_const_base(1);
+        return json_with_const_base(1); // NOLINT(modernize-return-braced-init-list): {1} would be an array
     }
     return json_with_const_base::array({make_nested_array(depth - 1)});
 }

tests/src/unit-disabled_exceptions.cpp

@@ -14,6 +14,9 @@ DOCTEST_GCC_SUPPRESS_WARNING("-Wnoexcept")
 
 #include <nlohmann/json.hpp>
 using json = nlohmann::json;
+#ifdef JSON_TEST_NO_GLOBAL_UDLS
+    using namespace nlohmann::literals; // NOLINT(google-build-using-namespace)
+#endif
 
 /////////////////////////////////////////////////////////////////////
 // for #2824

tests/src/unit-element_access2.cpp

@@ -1963,8 +1963,8 @@ TEST_CASE("operator[] with user-defined std::string_view-convertible types")
     };
 
     json j = {{"foo", "from_class"}, {"bar", "from_struct"}};
-    TestClass foo_obj;
-    TestStruct bar_obj;
+    const TestClass foo_obj;
+    const TestStruct bar_obj;
 
     SECTION("read access")
     {
@@ -2005,6 +2005,10 @@ TEST_CASE("keys convertible to std::string_view work with all lookup functions (
     // 3.12.0, such a key worked with at, the const operator[], find, count and
     // contains via the conversion to std::string; #4958 made the KeyType&&
     // templates win overload resolution for it instead, and those then failed
+    // the lookups pick the conversion to std::string_view, which leaves the one
+    // to std::string unused; it has to exist to reproduce the ambiguity
+    DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
+    DOCTEST_CLANG_SUPPRESS_WARNING("-Wunused-member-function")
     struct DualKey
     {
         operator std::string() const
@@ -2016,6 +2020,7 @@ TEST_CASE("keys convertible to std::string_view work with all lookup functions (
             return "a";
         }
     };
+    DOCTEST_CLANG_SUPPRESS_WARNING_POP
 
     SECTION("nlohmann::json")
     {

tests/src/unit-modifiers.cpp

@@ -1162,6 +1162,7 @@ TEST_CASE("update() on deeply nested values")
 
 TEST_CASE("update() with an argument that aliases *this (#5641)")
 {
+#if !defined(JSON_NOEXCEPTION) // checks which exception is thrown, and that nothing changed
     SECTION("the target is checked before the argument, as before the copy")
     {
         json j = 1;
@@ -1172,6 +1173,7 @@ TEST_CASE("update() with an argument that aliases *this (#5641)")
         CHECK_THROWS_WITH_AS(k.update(json::array()), "[json.exception.type_error.312] cannot use update() with array", json::type_error&);
         CHECK(k == json::object());
     }
+#endif
 
     SECTION("const reference")
     {

tests/src/unit-msgpack.cpp

@@ -1560,7 +1560,7 @@ TEST_CASE("MessagePack")
             // dump() still requires valid UTF-8 and throws for such a value,
             // unless an error handler that replaces or ignores the bytes is
             // passed
-            CHECK_THROWS_AS(j_value.dump(), json::type_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(j_value.dump()), json::type_error&);
 
             // the same bytes as an object key round-trip as well
             const std::vector<uint8_t> ill_formed_key = {0x81, 0xa2, 0xc0, 0xae, 0x01};

tests/src/unit-ordered_map.cpp

@@ -430,8 +430,8 @@ TEST_CASE("ordered_map")
 
         SECTION("with T& (lvalue)")
         {
-            std::string one = "1";
-            std::string four = "four";
+            std::string one = "1"; // NOLINT(misc-const-correctness): emplace must accept a non-const lvalue
+            std::string four = "four"; // NOLINT(misc-const-correctness): see above
 
             auto res1 = om.emplace("eins", one);
             CHECK(res1.first == om.begin());
@@ -467,7 +467,7 @@ TEST_CASE("ordered_map")
         SECTION("with key of key_type (non-template overload)")
         {
             const std::string key_vier{"vier"};
-            std::string four = "four";
+            std::string four = "four"; // NOLINT(misc-const-correctness): emplace must accept a non-const lvalue
 
             auto res4 = om.emplace(key_vier, four);
             CHECK(res4.first == om.begin() + 3);

tests/src/unit-ubjson.cpp

@@ -2520,7 +2520,7 @@ TEST_CASE("Universal Binary JSON Specification Examples 1")
             CHECK_NOTHROW(j = json::from_ubjson(v));
             REQUIRE(j.is_string());
             CHECK(j.get_ref<const json::string_t&>() == std::string("\xc0\xae"));
-            CHECK_THROWS_AS(j.dump(), json::type_error&);
+            CHECK_THROWS_AS(utils::ignore_return_value(j.dump()), json::type_error&);
             CHECK(json::from_ubjson(json::to_ubjson(j)) == j);
 
             // the same bytes as an object key round-trip as well

tests/src/unit-wstring.cpp

@@ -37,10 +37,10 @@ TEST_CASE("wide strings")
         // 32-bit wchar_t first encodes it as an ill-formed three-byte
         // sequence (rejected one byte later, at column 3)
         const char* const error_low_surrogate = sizeof(wchar_t) == 2
-                                                ? "[json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '\"<U+0000>'"
+                                                ? "[json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '\"\xFF'"
                                                 : "[json.exception.parse_error.101] parse error at line 1, column 3: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '\"\xED\xB0'";
         const char* const error_high_surrogate = sizeof(wchar_t) == 2
-            ? "[json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '\"<U+0000>'"
+            ? "[json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '\"\xFF'"
             : "[json.exception.parse_error.101] parse error at line 1, column 3: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '\"\xED\xA0'";
 
         // a lone low surrogate cannot start a pair