Restore the CI spelling of json_pointer's operator string_t in the API surface

The develop merge regenerated api_surface.json on macOS, whose libclang spells the name of the deprecated conversion operator as "operator nlohmann::json_pointer::string_t_helper<...>::type". CI's pinned libclang 18.1.1 on Linux spells it "operator typename string_t_helper<...>::type", so check_api_docs reported the file as out of date. This restores CI's spelling, which is byte-identical to the file CI regenerated. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Address Codacy findings in the API checker scripts
2026-09-28 02:30:32 +00:00 · 2026-09-27 21:37:14 +02:00 · 2026-09-27 18:09:03 +02:00 · 2026-09-27 18:07:00 +02:00 · 2026-09-15 10:06:55 +02:00 · 2026-09-14 21:26:29 +02:00
132 changed files with 72465 additions and 420 deletions
@@ -0,0 +1,81 @@
+name: "Check API documentation"
+
+on:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  check_api_docs:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
+        with:
+          egress-policy: audit
+
+      - name: Checkout pull request
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+
+      - name: Install clang
+        # Used only as a subprocess for `clang++ -E -v` system-include-path discovery in
+        # extract_api.py; it does not need to version-match the pinned libclang pip wheel
+        # below, which does the actual AST parsing. Do not "fix" this to be version-matched.
+        run: sudo apt-get update && sudo apt-get install -y clang
+
+      - name: Install Python dependencies
+        run: pip install -r tools/api_checker/requirements.txt
+
+      - name: Extract API and regenerate the committed surface file
+        run: |
+          python3 tools/api_checker/extract_api.py \
+            --header include/nlohmann/json.hpp \
+            --include include \
+            --output /tmp/api_snapshot.json \
+            --surface-output tools/api_checker/api_surface.json
+
+      - name: "Check API documentation (Phase 1: advisory)"
+        # Surfaces missing/broken @sa links without failing the job while the backlog from the
+        # initial AST-based rollout is burned down. See tools/api_checker/POLICY.md and the PR
+        # that introduced this workflow for the two-phase rollout plan.
+        continue-on-error: true
+        run: |
+          python3 tools/api_checker/check_docs.py \
+            --snapshot /tmp/api_snapshot.json
+
+      - name: Check macro documentation (advisory only)
+        # Cross-checks docs/mkdocs/docs/api/macros/ pages against #define sites. Only checks the
+        # documented-macro-still-exists direction; never blocks CI. See POLICY.md.
+        run: python3 tools/api_checker/check_macros.py
+
+      - name: Check for uncommitted API surface changes
+        id: diff
+        run: |
+          mkdir -p ${{ github.workspace }}/patch
+          git diff --patch --no-color -- tools/api_checker/api_surface.json > ${{ github.workspace }}/patch/api_surface.patch
+          if [ -s ${{ github.workspace }}/patch/api_surface.patch ]; then
+            echo "tools/api_checker/api_surface.json is out of date. Diff:"
+            cat ${{ github.workspace }}/patch/api_surface.patch
+            echo "has_diff=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "has_diff=false" >> "$GITHUB_OUTPUT"
+          fi
+
+      # Uploaded so contributors can fix their PR with `git apply api_surface.patch`
+      # instead of installing libclang locally.
+      - name: Upload patch
+        if: steps.diff.outputs.has_diff == 'true'
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: api-surface-patch
+          path: patch/api_surface.patch
+
+      - name: Fail if API surface file is not up to date
+        # Unlike the doc-backlog check above, this is purely mechanical regeneration with no
+        # backlog to phase in -- blocking from the start, matching check_amalgamation.yml's
+        # precedent. Contributors who add/remove/rename public API must regenerate and commit
+        # tools/api_checker/api_surface.json as part of their PR.
+        if: steps.diff.outputs.has_diff == 'true'
+        run: exit 1
@@ -3,6 +3,7 @@
 *.gcno
 *.gcda
 .DS_Store
+__pycache__/

 /.idea
 /cmake-build-*
@@ -43,5 +44,9 @@ venv

 nlohmann_json.spdx

+# api_checker: ephemeral, location/doc-status-sensitive working file (not the committed
+# release-tracking artifact -- see tools/api_checker/api_surface.json for that)
+/tools/api_checker/api_snapshot.json
+
 # Bazel-related
 MODULE.bazel.lock
@@ -106,7 +106,7 @@ Thanks everyone!

 :books: If you want to **learn more** about how to use the library, check out the rest of the [**README**](#examples), have a look at [**code examples**](https://github.com/nlohmann/json/tree/develop/docs/mkdocs/docs/examples), or browse through the [**help pages**](https://json.nlohmann.me).

-:construction: If you want to understand the **API** better, check out the [**API Reference**](https://json.nlohmann.me/api/basic_json/) or have a look at the [quick reference](#quick-reference) below.
+:construction: If you want to understand the **API** better, check out the [**API Reference**](https://json.nlohmann.me/api/basic_json/) or have a look at the [quick reference](#quick-reference) below. The public API surface is derived mechanically and checked for documentation coverage by the tooling in [`tools/api_checker/`](tools/api_checker/), whose [POLICY.md](tools/api_checker/POLICY.md) defines what counts as public API and what stability is guaranteed.

 :bug: If you found a **bug**, please check the [**FAQ**](https://json.nlohmann.me/home/faq/) if it is a known issue or the result of a design decision. Please also have a look at the [**issue list**](https://github.com/nlohmann/json/issues) before you [**create a new issue**](https://github.com/nlohmann/json/issues/new/choose). Please provide as much information as possible to help us understand and reproduce your issue.

@@ -420,7 +420,9 @@ basic_json(basic_json&& other) noexcept;
 1. Since version 1.0.0.
 2. Since version 1.0.0.
 3. Since version 2.1.0.
-4. Since version 3.2.0.
+4. Since version 3.2.0. Also initializes the position reported by
+   [`start_pos()`](start_pos.md)/[`end_pos()`](end_pos.md) from `val` when
+   [`JSON_DIAGNOSTIC_POSITIONS`](../macros/json_diagnostic_positions.md) is enabled, since version 3.12.0.
 5. Since version 1.0.0.
 6. Since version 1.0.0.
 7. Since version 1.0.0.
@@ -0,0 +1,38 @@
+# <small>nlohmann::basic_json::</small>bjdata_version_t
+
+```cpp
+enum class bjdata_version_t
+{
+    draft2,
+    draft3,
+};
+```
+
+This enumeration is used in the [`to_bjdata`](to_bjdata.md) function to choose which draft version of
+the BJData specification to encode ND-array extensions for:
+
+draft2
+:   encode using the BJData Draft 2 ND-array format
+
+draft3
+:   encode using the BJData Draft 3 ND-array format
+
+## Examples
+
+??? example
+
+    The example shows how `bjdata_version_t` selects the BJData draft used by `to_bjdata`.
+
+    ```cpp
+    --8<-- "examples/bjdata_version_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/bjdata_version_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.12.0.
@@ -18,8 +18,7 @@ ignore
 :   ignore tags

 store
-:   store tagged byte strings (for bytes 0xd8..0xdb) as binary values with the tag as subtype; other tagged values are
-    read as if the tag were ignored. If several tags precede a byte string, only the innermost one is stored.
+:   store tagged byte strings (for bytes 0xd8..0xdb) as binary values with the tag as subtype; other tagged values are read as if the tag were ignored. If several tags precede a byte string, only the innermost one is stored.

 ## Examples

@@ -0,0 +1,32 @@
+# <small>nlohmann::basic_json::</small>initializer_list_t
+
+```cpp
+using initializer_list_t = std::initializer_list<detail::json_ref<basic_json>>;
+```
+
+The type used for the initializer-list [constructor](basic_json.md) (overload 5) and for functions
+such as [`operator=`](operator=.md) that accept a braced-init-list of JSON values. Each element wraps a
+`basic_json` value or something convertible to one, deferring the decision of whether the list should be
+parsed as a JSON array or a JSON object to the constructor itself.
+
+See the [constructor](basic_json.md) documentation for how `initializer_list_t` values are interpreted.
+
+## Examples
+
+??? example
+
+    The example shows how an `initializer_list_t` is used to construct a JSON value.
+
+    ```cpp
+    --8<-- "examples/initializer_list_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/initializer_list_t.output"
+    ```
+
+## Version history
+
+- Since version 1.0.0.
@@ -0,0 +1,31 @@
+# <small>nlohmann::basic_json::</small>json_sax_t
+
+```cpp
+using json_sax_t = json_sax<basic_json>;
+```
+
+The [`json_sax`](../json_sax/index.md) interface bound to this `basic_json` specialization, i.e. with
+`BasicJsonType` fixed to `basic_json`. Used as the SAX interface type by [`sax_parse`](sax_parse.md) and
+other SAX-based parsing functions.
+
+See [`nlohmann::json_sax`](../json_sax/index.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `json_sax_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -51,3 +51,5 @@ Linear.
 ## Version history

 - Added in version 1.0.0.
+- The `noexcept` specification was extended to also depend on
+  [`json_base_class_t`](json_base_class_t.md)'s move-assignment in version 3.11.3.
@@ -85,3 +85,8 @@ Linear in the size of the JSON value.
 - Since version 1.0.0.
 - Macros `JSON_EXPLICIT`/[`JSON_USE_IMPLICIT_CONVERSIONS`](../macros/json_use_implicit_conversions.md) added
  in version 3.9.0.
+- The exclusion of `std::any` from this conversion became conditional on
+  [`JSON_HAS_STATIC_RTTI`](../macros/json_has_static_rtti.md) in version 3.11.3.
+- `std::optional<T>` excluded from this conversion in version 3.13.0; use
+  [`get<std::optional<T>>()`](get.md)/[`get_to()`](get_to.md) instead (see
+  [Converting values](../../features/conversions.md)).
@@ -0,0 +1,32 @@
+# <small>nlohmann::byte_container_with_subtype::</small>container_type
+
+```cpp
+using container_type = BinaryType;
+```
+
+The type of the underlying binary container, forwarded from the `BinaryType` template parameter that
+`byte_container_with_subtype` is instantiated with. `byte_container_with_subtype` publicly inherits from
+`container_type`.
+
+See [`basic_json::binary_t`](../basic_json/binary_t.md) for the type typically used to instantiate
+`BinaryType`.
+
+## Examples
+
+??? example
+
+    The example shows the type `container_type`.
+
+    ```cpp
+    --8<-- "examples/byte_container_with_subtype__container_type.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/byte_container_with_subtype__container_type.output"
+    ```
+
+## Version history
+
+- Since version 3.8.0.
@@ -0,0 +1,45 @@
+# <small>nlohmann::byte_container_with_subtype::</small>operator==
+
+```cpp
+bool operator==(const byte_container_with_subtype& rhs) const;
+```
+
+Compares two `byte_container_with_subtype` values for equality by comparing the underlying binary
+container, the subtype, and whether a subtype is set.
+
+## Parameters
+
+`rhs` (in)
+:   value to compare `*this` against
+
+## Return value
+
+whether `*this` and `rhs` are equal
+
+## Exception safety
+
+No-throw guarantee: this function never throws exceptions.
+
+## Complexity
+
+Linear in the size of the underlying binary container.
+
+## Examples
+
+??? example
+
+    The example demonstrates comparing `byte_container_with_subtype` values.
+
+    ```cpp
+    --8<-- "examples/byte_container_with_subtype__operator_eq.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/byte_container_with_subtype__operator_eq.output"
+    ```
+
+## Version history
+
+- Since version 3.8.0.
@@ -0,0 +1,45 @@
+# <small>nlohmann::byte_container_with_subtype::</small>operator!=
+
+```cpp
+bool operator!=(const byte_container_with_subtype& rhs) const;
+```
+
+Compares two `byte_container_with_subtype` values for inequality. Implemented as the negation of
+[`operator==`](operator_eq.md).
+
+## Parameters
+
+`rhs` (in)
+:   value to compare `*this` against
+
+## Return value
+
+whether `*this` and `rhs` are not equal
+
+## Exception safety
+
+No-throw guarantee: this function never throws exceptions.
+
+## Complexity
+
+Linear in the size of the underlying binary container.
+
+## Examples
+
+??? example
+
+    The example demonstrates comparing `byte_container_with_subtype` values.
+
+    ```cpp
+    --8<-- "examples/byte_container_with_subtype__operator_ne.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/byte_container_with_subtype__operator_ne.output"
+    ```
+
+## Version history
+
+- Since version 3.8.0.
@@ -0,0 +1,28 @@
+# <small>nlohmann::byte_container_with_subtype::</small>subtype_type
+
+```cpp
+using subtype_type = std::uint64_t;
+```
+
+The type used to store the optional binary subtype tag. See [`subtype`](subtype.md) and
+[`set_subtype`](set_subtype.md).
+
+## Examples
+
+??? example
+
+    The example shows the type `subtype_type`.
+
+    ```cpp
+    --8<-- "examples/byte_container_with_subtype__subtype_type.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/byte_container_with_subtype__subtype_type.output"
+    ```
+
+## Version history
+
+- Since version 3.8.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>binary_t
+
+```cpp
+using binary_t = typename BasicJsonType::binary_t;
+```
+
+The type used by the [`binary`](binary.md) callback for JSON binary values, forwarded from the
+`BasicJsonType` template parameter.
+
+See [`basic_json::binary_t`](../basic_json/binary_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `binary_t` and its relation to `basic_json::binary_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__binary_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__binary_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.8.0.
@@ -0,0 +1,33 @@
+# <small>nlohmann::json_sax::</small>json_sax
+
+```cpp
+// (1)
+json_sax() = default;
+
+// (2)
+json_sax(const json_sax&) = default;
+
+// (3)
+json_sax(json_sax&&) noexcept = default;
+```
+
+1. Default constructor.
+2. Copy constructor.
+3. Move constructor.
+
+`json_sax` is a pure abstract base class with no data members of its own, so all three constructors are
+defaulted and only exist to make derived SAX consumers explicitly copyable/movable.
+
+## Exception safety
+
+No-throw guarantee: none of these constructors throw exceptions.
+
+## Complexity
+
+Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>number_float_t
+
+```cpp
+using number_float_t = typename BasicJsonType::number_float_t;
+```
+
+The type used by the [`number_float`](number_float.md) callback for JSON floating-point numbers,
+forwarded from the `BasicJsonType` template parameter.
+
+See [`basic_json::number_float_t`](../basic_json/number_float_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `number_float_t` and its relation to `basic_json::number_float_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__number_float_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__number_float_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>number_integer_t
+
+```cpp
+using number_integer_t = typename BasicJsonType::number_integer_t;
+```
+
+The type used by the [`number_integer`](number_integer.md) callback for JSON integer numbers, forwarded
+from the `BasicJsonType` template parameter.
+
+See [`basic_json::number_integer_t`](../basic_json/number_integer_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `number_integer_t` and its relation to `basic_json::number_integer_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__number_integer_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__number_integer_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>number_unsigned_t
+
+```cpp
+using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+```
+
+The type used by the [`number_unsigned`](number_unsigned.md) callback for JSON unsigned integer numbers,
+forwarded from the `BasicJsonType` template parameter.
+
+See [`basic_json::number_unsigned_t`](../basic_json/number_unsigned_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `number_unsigned_t` and its relation to `basic_json::number_unsigned_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__number_unsigned_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__number_unsigned_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,29 @@
+# <small>nlohmann::json_sax::</small>operator=
+
+```cpp
+// (1)
+json_sax& operator=(const json_sax&) = default;
+
+// (2)
+json_sax& operator=(json_sax&&) noexcept = default;
+```
+
+1. Copy assignment operator.
+2. Move assignment operator.
+
+`json_sax` is a pure abstract base class with no data members of its own, so both assignment operators
+are defaulted and only exist to make derived SAX consumers explicitly copy-/move-assignable.
+
+## Exception safety
+
+No-throw guarantee: neither operator throws exceptions.
+
+## Complexity
+
+Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>string_t
+
+```cpp
+using string_t = typename BasicJsonType::string_t;
+```
+
+The type used by the [`string`](string.md) and [`key`](key.md) callbacks for JSON strings and object
+keys, forwarded from the `BasicJsonType` template parameter.
+
+See [`basic_json::string_t`](../basic_json/string_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `string_t` and its relation to `basic_json::string_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__string_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__string_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,22 @@
+# <small>nlohmann::json_sax::</small>~json_sax
+
+```cpp
+virtual ~json_sax() = default;
+```
+
+Destructor. Virtual to allow proper destruction of derived SAX consumer classes through a
+pointer/reference to `json_sax`.
+
+## Exception safety
+
+No-throw guarantee: this destructor never throws exceptions.
+
+## Complexity
+
+Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.2.0.
@@ -8,16 +8,16 @@ This type preserves the insertion order of object keys.

 ## Iterator invalidation

-The type is based on [`ordered_map`](ordered_map.md) which in turn uses a `std::vector` to store object elements.
+The type is based on [`ordered_map`](ordered_map/index.md) which in turn uses a `std::vector` to store object elements.
 Therefore, adding object elements can yield a reallocation in which case all iterators (including the
 [`end()`](basic_json/end.md) iterator) and all references to the elements are invalidated. Also, any iterator or
 reference after the insertion point will point to the same index, which is now a different value.

 ## Complexity

-[`ordered_map`](ordered_map.md) has no lookup index: every key-based object operation is a linear scan, so building or
+[`ordered_map`](ordered_map/index.md) has no lookup index: every key-based object operation is a linear scan, so building or
 parsing an object of `n` keys costs O(n²) rather than O(n log n). See
-[`ordered_map` complexity](ordered_map.md#complexity) for the per-operation table and for measured numbers.
+[`ordered_map` complexity](ordered_map/index.md#complexity) for the per-operation table and for measured numbers.

 ## Examples

@@ -37,7 +37,7 @@ parsing an object of `n` keys costs O(n²) rather than O(n log n). See

 ## See also

- [ordered_map](ordered_map.md)
+- [ordered_map](ordered_map/index.md)
 - [Object Order](../features/object_order.md)

 ## Version history
@@ -0,0 +1,28 @@
+# <small>nlohmann::ordered_map::</small>Container
+
+```cpp
+using Container = std::vector<std::pair<const Key, T>, Allocator>;
+```
+
+The base container type that `ordered_map` publicly inherits from. Elements are stored in insertion
+order as `#!cpp std::pair<const Key, T>` entries in a `std::vector`.
+
+## Examples
+
+??? example
+
+    The example shows the type `Container`.
+
+    ```cpp
+    --8<-- "examples/ordered_map__Container.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__Container.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,61 @@
+# <small>nlohmann::ordered_map::</small>at
+
+```cpp
+// (1)
+T& at(const key_type& key);
+const T& at(const key_type& key) const;
+
+// (2)
+template<class KeyType>
+T& at(KeyType&& key);
+template<class KeyType>
+const T& at(KeyType&& key) const;
+```
+
+1. Returns a reference to the value mapped to `key`.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup, e.g. looking up by a `#!cpp const char*` without constructing a temporary
+   `key_type`). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to find
+
+## Return value
+
+reference to the mapped value of the element with key equal to `key`
+
+## Exceptions
+
+Throws `std::out_of_range` if no element with key `key` exists.
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `at` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__at.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__at.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,53 @@
+# <small>nlohmann::ordered_map::</small>count
+
+```cpp
+// (1)
+size_type count(const key_type& key) const;
+
+// (2)
+template<class KeyType>
+size_type count(KeyType&& key) const;
+```
+
+1. Returns the number of elements with key equal to `key` (0 or 1, since keys are unique).
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the elements to count
+
+## Return value
+
+number of elements with key equal to `key` (0 or 1)
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `count` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__count.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__count.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,58 @@
+# <small>nlohmann::ordered_map::</small>emplace
+
+```cpp
+// (1)
+std::pair<iterator, bool> emplace(const key_type& key, T&& t);
+
+// (2)
+template<class KeyType>
+std::pair<iterator, bool> emplace(KeyType&& key, T&& t);
+```
+
+1. Inserts `#!cpp {key, t}` if no element with an equal key already exists (per [`key_compare`](key_compare.md)),
+   appending it at the end to preserve insertion order. If an equal key already exists, does nothing.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to insert
+
+`t` (in)
+:   value of the element to insert
+
+## Return value
+
+pair of an iterator to the (possibly newly inserted) element, and a `bool` that is `true` if insertion
+took place and `false` if an element with an equal key already existed
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `emplace` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__emplace.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__emplace.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,75 @@
+# <small>nlohmann::ordered_map::</small>erase
+
+```cpp
+// (1)
+size_type erase(const key_type& key);
+
+// (2)
+template<class KeyType>
+size_type erase(KeyType&& key);
+
+// (3)
+iterator erase(iterator pos);
+
+// (4)
+iterator erase(iterator first, iterator last);
+```
+
+1. Removes the element with key equal to `key`, if any, preserving the relative order of the remaining
+   elements.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+3. Removes the element at `pos`.
+4. Removes the elements in range `[first, last)`.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to remove
+
+`pos` (in)
+:   iterator to the element to remove
+
+`first` (in)
+:   iterator to the first element to remove
+
+`last` (in)
+:   iterator one past the last element to remove
+
+## Return value
+
+1. number of elements removed (0 or 1)
+2. number of elements removed (0 or 1)
+3. iterator following the removed element
+4. iterator following the last removed element
+
+## Complexity
+
+Linear in the number of elements (elements after the removed one(s) are shifted to keep storage
+contiguous).
+
+## Examples
+
+??? example
+
+    The example shows how `erase` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__erase.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__erase.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,56 @@
+# <small>nlohmann::ordered_map::</small>find
+
+```cpp
+// (1)
+iterator find(const key_type& key);
+const_iterator find(const key_type& key) const;
+
+// (2)
+template<class KeyType>
+iterator find(KeyType&& key);
+template<class KeyType>
+const_iterator find(KeyType&& key) const;
+```
+
+1. Returns an iterator to the element with key equal to `key`, or `end()` if no such element exists.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to find
+
+## Return value
+
+iterator to the element with key equal to `key`, or `end()` if not found
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `find` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__find.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__find.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -6,7 +6,7 @@ template<class Key, class T, class IgnoredLess = std::less<Key>,
 struct ordered_map : std::vector<std::pair<const Key, T>, Allocator>;
 ```

-A minimal map-like container that preserves insertion order for use within [`nlohmann::ordered_json`](ordered_json.md)
+A minimal map-like container that preserves insertion order for use within [`nlohmann::ordered_json`](../ordered_json.md)
 (`nlohmann::basic_json<ordered_map>`).

 ## Template parameters
@@ -32,12 +32,12 @@ case all iterators (including the `end()` iterator) and all references to the el

 - **key_type** - key type (`Key`)
 - **mapped_type** - mapped type (`T`)
- **Container** - base container type (`#!cpp std::vector<std::pair<const Key, T>, Allocator>`)
+- [**Container**](Container.md) - base container type (`#!cpp std::vector<std::pair<const Key, T>, Allocator>`)
 - **iterator**
 - **const_iterator**
 - **size_type**
 - **value_type**
- **key_compare** - key comparison function
+- [**key_compare**](key_compare.md) - key comparison function
 ```cpp
 std::equal_to<Key>  // until C++14

@@ -46,15 +46,16 @@ std::equal_to<>     // since C++14

 ## Member functions

- (constructor)
- (destructor)
- **emplace**
- **operator\[\]**
- **at**
- **erase**
- **count**
- **find**
- **insert**
+- [(constructor)](ordered_map.md)
+- [(destructor)](~ordered_map.md)
+- [**operator=**](operator=.md)
+- [**emplace**](emplace.md)
+- [**operator\[\]**](operator[].md)
+- [**at**](at.md)
+- [**erase**](erase.md)
+- [**count**](count.md)
+- [**find**](find.md)
+- [**insert**](insert.md)

 ## Complexity

@@ -116,9 +117,9 @@ This differs from `#!cpp std::map`, where the same operations are O(log n).

 ## See also

- [ordered_json](ordered_json.md)
+- [ordered_json](../ordered_json.md)

 ## Version history

- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](ordered_json.md).
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
 - Added **key_compare** member in version 3.11.0.
@@ -0,0 +1,63 @@
+# <small>nlohmann::ordered_map::</small>insert
+
+```cpp
+// (1)
+std::pair<iterator, bool> insert(value_type&& value);
+std::pair<iterator, bool> insert(const value_type& value);
+
+// (2)
+template<typename InputIt>
+void insert(InputIt first, InputIt last);
+```
+
+1. Inserts `value` if no element with an equal key already exists (per [`key_compare`](key_compare.md)),
+   appending it at the end to preserve insertion order. If an equal key already exists, does nothing.
+2. Inserts the elements from range `[first, last)`, in iteration order, applying the same equal-key rule
+   as (1) to each element.
+
+## Template parameters
+
+`InputIt`
+:   an input iterator type
+
+## Parameters
+
+`value` (in)
+:   value to insert
+
+`first` (in)
+:   iterator to the first element to insert
+
+`last` (in)
+:   iterator one past the last element to insert
+
+## Return value
+
+1. pair of an iterator to the (possibly newly inserted) element, and a `bool` that is `true` if insertion
+   took place and `false` if an element with an equal key already existed
+2. (none)
+
+## Complexity
+
+1. Linear in the number of elements.
+2. Linear in the distance between `first` and `last`, times linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `insert` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__insert.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__insert.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,34 @@
+# <small>nlohmann::ordered_map::</small>key_compare
+
+```cpp
+using key_compare = std::equal_to<Key>;  // until C++14
+
+using key_compare = std::equal_to<>;     // since C++14
+```
+
+The comparator used to determine key equality when looking up elements. Unlike `std::map`, `ordered_map`
+uses linear search with `key_compare` rather than an ordering relation, since element order reflects
+insertion order rather than key order.
+
+Since C++14, the transparent `#!cpp std::equal_to<>` is used, which enables heterogeneous lookup (e.g.
+looking up by a `#!cpp const char*` key without constructing a temporary `Key`).
+
+## Examples
+
+??? example
+
+    The example shows how `key_compare` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__key_compare.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__key_compare.output"
+    ```
+
+## Version history
+
+- Added in version 3.11.0.
@@ -0,0 +1,32 @@
+# <small>nlohmann::ordered_map::</small>operator=
+
+```cpp
+// (1)
+ordered_map& operator=(const ordered_map& other);
+
+// (2)
+ordered_map& operator=(ordered_map&& other) noexcept(std::is_nothrow_move_assignable<Container>::value);
+```
+
+1. Copy assignment operator.
+2. Move assignment operator.
+
+## Parameters
+
+`other` (in)
+:   value to assign from
+
+## Return value
+
+`*this`
+
+## Complexity
+
+1. Linear in the size of `other`.
+2. Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,62 @@
+# <small>nlohmann::ordered_map::</small>operator[]
+
+```cpp
+// (1)
+T& operator[](const key_type& key);
+const T& operator[](const key_type& key) const;
+
+// (2)
+template<class KeyType>
+T& operator[](KeyType&& key);
+template<class KeyType>
+const T& operator[](KeyType&& key) const;
+```
+
+1. Returns a reference to the value mapped to `key`, inserting a default-constructed `T` (non-`const`
+   overload only) if no such element exists yet.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to find or insert
+
+## Return value
+
+reference to the mapped value of the element with key equal to `key`
+
+## Exceptions
+
+The `const` overloads throw `std::out_of_range` if no element with key `key` exists (they delegate to
+[`at`](at.md)).
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `operator[]` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__operator_idx.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__operator_idx.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,66 @@
+# <small>nlohmann::ordered_map::</small>ordered_map
+
+```cpp
+// (1)
+ordered_map() noexcept(noexcept(Container()));
+
+// (2)
+explicit ordered_map(const Allocator& alloc) noexcept(noexcept(Container(alloc)));
+
+// (3)
+template <class It>
+ordered_map(It first, It last, const Allocator& alloc = Allocator());
+
+// (4)
+ordered_map(std::initializer_list<value_type> init, const Allocator& alloc = Allocator());
+
+// (5)
+ordered_map(const ordered_map&) = default;
+
+// (6)
+ordered_map(ordered_map&&) noexcept(std::is_nothrow_move_constructible<Container>::value) = default;
+```
+
+1. Default constructor. Creates an empty `ordered_map`.
+2. Creates an empty `ordered_map` using the given allocator.
+3. Creates an `ordered_map` from the elements in range `[first, last)`, inserted in iteration order.
+4. Creates an `ordered_map` from an initializer list of key/value pairs, inserted in list order.
+5. Copy constructor.
+6. Move constructor.
+
+These constructors are declared explicitly (rather than inherited via `#!cpp using Container::Container`)
+because older compilers (GCC <= 5.5, Xcode <= 9.4) do not handle the inherited constructors correctly.
+
+## Template parameters
+
+`It`
+:   an input iterator type
+
+## Parameters
+
+`alloc` (in)
+:   allocator to use for the underlying container
+
+`first` (in)
+:   iterator to the first element to insert
+
+`last` (in)
+:   iterator one past the last element to insert
+
+`init` (in)
+:   initializer list of key/value pairs to insert
+
+## Complexity
+
+1. Constant.
+2. Constant.
+3. Linear in the distance between `first` and `last`.
+4. Linear in the size of `init`.
+5. Linear in the size of `other`.
+6. Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,17 @@
+# <small>nlohmann::ordered_map::</small>~ordered_map
+
+```cpp
+~ordered_map() = default;
+```
+
+Destroys the `ordered_map` and frees all allocated memory.
+
+## Complexity
+
+Linear in the number of elements.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,21 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // an empty binary value is encoded differently by the two drafts:
+    // draft2 omits the optimized type marker for an empty byte array,
+    // while draft3 always writes it
+    json j = json::binary({});
+
+    // encode using BJData draft2 (the default)
+    auto v_draft2 = json::to_bjdata(j, true, true, json::bjdata_version_t::draft2);
+
+    // encode using BJData draft3
+    auto v_draft3 = json::to_bjdata(j, true, true, json::bjdata_version_t::draft3);
+
+    std::cout << "draft2 size: " << v_draft2.size() << '\n'
+              << "draft3 size: " << v_draft3.size() << std::endl;
+}
@@ -0,0 +1,2 @@
+draft2 size: 4
+draft3 size: 6
@@ -0,0 +1,11 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<byte_container_with_subtype::container_type, std::vector<std::uint8_t>>::value
+              << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,15 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
+
+int main()
+{
+    byte_container_with_subtype c1({0xca, 0xfe});
+    byte_container_with_subtype c2({0xca, 0xfe});
+    byte_container_with_subtype c3({0xca, 0xfe}, 42);
+
+    std::cout << std::boolalpha
+              << "c1 == c2: " << (c1 == c2) << '\n'
+              << "c1 == c3: " << (c1 == c3) << std::endl;
+}
@@ -0,0 +1,2 @@
+c1 == c2: true
+c1 == c3: false
@@ -0,0 +1,15 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
+
+int main()
+{
+    byte_container_with_subtype c1({0xca, 0xfe});
+    byte_container_with_subtype c2({0xca, 0xfe});
+    byte_container_with_subtype c3({0xca, 0xfe}, 42);
+
+    std::cout << std::boolalpha
+              << "c1 != c2: " << (c1 != c2) << '\n'
+              << "c1 != c3: " << (c1 != c3) << std::endl;
+}
@@ -0,0 +1,2 @@
+c1 != c2: false
+c1 != c3: true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<byte_container_with_subtype::subtype_type, std::uint64_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,13 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // an initializer_list_t is what a braced-init-list of JSON values is deduced as
+    json::initializer_list_t init = {"a", 1, 2.0, false};
+
+    json j(init);
+    std::cout << j.dump() << std::endl;
+}
@@ -0,0 +1 @@
+["a",1,2.0,false]
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::binary_t, json::binary_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::number_float_t, json::number_float_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::number_integer_t, json::number_integer_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::number_unsigned_t, json::number_unsigned_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::string_t, json::string_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t, nlohmann::json_sax<json>>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,12 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    using Map = nlohmann::ordered_map<std::string, int>;
+
+    std::cout << std::boolalpha
+              << "Container is std::vector<std::pair<const Key, T>>: "
+              << std::is_same<Map::Container, std::vector<std::pair<const std::string, int>>>::value
+              << std::endl;
+}
@@ -0,0 +1 @@
+Container is std::vector<std::pair<const Key, T>>: true
@@ -0,0 +1,26 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+    m["one"] = 1;
+    m["two"] = 2;
+
+    // access an existing element
+    std::cout << "m.at(\"one\") = " << m.at("one") << std::endl;
+
+    // modify through the reference returned by at()
+    m.at("two") = 22;
+    std::cout << "m.at(\"two\") = " << m.at("two") << std::endl;
+
+    // accessing a missing key throws
+    try
+    {
+        m.at("three");
+    }
+    catch (const std::out_of_range& e)
+    {
+        std::cout << "exception: " << e.what() << std::endl;
+    }
+}
@@ -0,0 +1,3 @@
+m.at("one") = 1
+m.at("two") = 22
+exception: key not found
@@ -0,0 +1,12 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+    m["one"] = 1;
+
+    std::cout << std::boolalpha
+              << "m.count(\"one\") = " << m.count("one") << '\n'
+              << "m.count(\"two\") = " << m.count("two") << std::endl;
+}
@@ -0,0 +1,2 @@
+m.count("one") = 1
+m.count("two") = 0
@@ -0,0 +1,15 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, std::string> m;
+
+    // emplace a new element
+    auto res1 = m.emplace("one", "eins");
+    std::cout << std::boolalpha << "inserted: " << res1.second << ", value: " << res1.first->second << std::endl;
+
+    // emplace with an already-existing key: no-op, returns the existing element
+    auto res2 = m.emplace("one", "uno");
+    std::cout << std::boolalpha << "inserted: " << res2.second << ", value: " << res2.first->second << std::endl;
+}
@@ -0,0 +1,2 @@
+inserted: true, value: eins
+inserted: false, value: eins
@@ -0,0 +1,24 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+    m["one"] = 1;
+    m["two"] = 2;
+    m["three"] = 3;
+
+    // erase by key
+    std::size_t removed = m.erase("two");
+    std::cout << "removed by key: " << removed << std::endl;
+
+    // erase by iterator
+    m.erase(m.begin());
+
+    std::cout << "remaining: ";
+    for (const auto& element : m)
+    {
+        std::cout << element.first << ' ';
+    }
+    std::cout << std::endl;
+}
@@ -0,0 +1,2 @@
+removed by key: 1
+remaining: three 
@@ -0,0 +1,19 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+    m["one"] = 1;
+
+    auto it = m.find("one");
+    if (it != m.end())
+    {
+        std::cout << "found: " << it->first << " = " << it->second << std::endl;
+    }
+
+    if (m.find("two") == m.end())
+    {
+        std::cout << "\"two\" not found" << std::endl;
+    }
+}
@@ -0,0 +1,2 @@
+found: one = 1
+"two" not found
@@ -0,0 +1,21 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+
+    // insert a single value
+    auto res = m.insert({"one", 1});
+    std::cout << std::boolalpha << "inserted: " << res.second << std::endl;
+
+    // insert a range from another container
+    std::vector<std::pair<const std::string, int>> more = {{"two", 2}, {"three", 3}};
+    m.insert(more.begin(), more.end());
+
+    for (const auto& element : m)
+    {
+        std::cout << element.first << ':' << element.second << ' ';
+    }
+    std::cout << std::endl;
+}
@@ -0,0 +1,2 @@
+inserted: true
+one:1 two:2 three:3 
@@ -0,0 +1,12 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    using Map = nlohmann::ordered_map<std::string, int>;
+    Map::key_compare compare{};
+
+    std::cout << std::boolalpha
+              << "compare(\"a\", \"a\") = " << compare("a", "a") << '\n'
+              << "compare(\"a\", \"b\") = " << compare("a", "b") << std::endl;
+}
@@ -0,0 +1,2 @@
+compare("a", "a") = true
+compare("a", "b") = false
@@ -0,0 +1,14 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+
+    // operator[] inserts a default-constructed value if the key doesn't exist yet
+    m["one"] = 1;
+    std::cout << "m[\"one\"] = " << m["one"] << std::endl;
+
+    // accessing again just returns the existing value
+    std::cout << "m[\"one\"] = " << m["one"] << std::endl;
+}
@@ -0,0 +1,2 @@
+m["one"] = 1
+m["one"] = 1
@@ -51,16 +51,16 @@ If you do want to preserve the **insertion order**, you can use the type [`nlohm
    --8<-- "examples/ordered_json.output"
    ```

-Alternatively, [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map) also preserves the insertion order and, unlike [`ordered_map`](../api/ordered_map.md), keeps a lookup index, so it does not have the quadratic cost described below. It is used through a small adapter ([integration](https://github.com/nlohmann/json/issues/485#issuecomment-333652309)).
+Alternatively, [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map) also preserves the insertion order and, unlike [`ordered_map`](../api/ordered_map/index.md), keeps a lookup index, so it does not have the quadratic cost described below. It is used through a small adapter ([integration](https://github.com/nlohmann/json/issues/485#issuecomment-333652309)).

 If the order does not matter and you only want faster lookup, `boost::unordered_flat_map`, `absl::flat_hash_map`, `absl::node_hash_map`, and several other hash maps work through an adapter that restores the template argument order `basic_json` expects; see [Template Parameter Requirements](types/template_parameters.md#objecttype). Note these are *unordered*, not insertion-ordered.

 [`tsl::ordered_map`](https://github.com/Tessil/ordered-map) cannot be used: its iterators expose the mapped value as `const`, while `basic_json` needs to modify it in place.

-The [`ordered_map`](../api/ordered_map.md) behind `nlohmann::ordered_json` is deliberately minimal and has no lookup
+The [`ordered_map`](../api/ordered_map/index.md) behind `nlohmann::ordered_json` is deliberately minimal and has no lookup
 index, so every key access is a linear scan and building an object of `n` keys costs O(n²). This is unnoticeable at
 typical object sizes but becomes significant for objects with many thousands of keys; see
-[`ordered_map` complexity](../api/ordered_map.md#complexity). The alternatives above keep a lookup index and do not
+[`ordered_map` complexity](../api/ordered_map/index.md#complexity). The alternatives above keep a lookup index and do not
 have this cost.

 ### Notes on parsing
@@ -37,7 +37,7 @@ Requirements are split into two groups:

 | Template parameter                                                | Default                           | Notable substitutes                                                   |
 |-------------------------------------------------------------------|-----------------------------------|-----------------------------------------------------------------------|
-| [`ObjectType`](#objecttype)                                       | `std::map`                        | [`nlohmann::ordered_map`](../../api/ordered_map.md), Abseil hash maps |
+| [`ObjectType`](#objecttype)                                       | `std::map`                        | [`nlohmann::ordered_map`](../../api/ordered_map/index.md), Abseil hash maps |
 | [`ArrayType`](#arraytype)                                         | `std::vector`                     | `#!cpp std::deque`                                                    |
 | [`StringType`](#stringtype)                                       | `std::string`                     | `std::string`-like types over `char`                                  |
 | [`BooleanType`](#booleantype)                                     | `bool`                            | none worth using                                                      |
@@ -230,7 +230,7 @@ The library does not sort or de-duplicate keys itself; the behavior described in
 | Container                                                                        | Notes                                                                         |
 |----------------------------------------------------------------------------------|-------------------------------------------------------------------------------|
 | `#!cpp std::map` (default)                                                       |                                                                               |
-| [`nlohmann::ordered_map`](../../api/ordered_map.md)                              | used by [`ordered_json`](../../api/ordered_json.md); keeps insertion order    |
+| [`nlohmann::ordered_map`](../../api/ordered_map/index.md)                              | used by [`ordered_json`](../../api/ordered_json.md); keeps insertion order    |
 | [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map)                     | keeps insertion order; adapter puts `fifo_map_compare` in the comparator slot |
 | `boost::container::map`, `boost::container::flat_map`                            | no adapter needed                                                             |
 | `#!cpp std::unordered_map`                                                       | through the adapter above; not with libstdc++ 9, see the note                 |
@@ -50,7 +50,7 @@ The public headers are in [`include/nlohmann`](https://github.com/nlohmann/json/
 - [`adl_serializer.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/adl_serializer.hpp), [`byte_container_with_subtype.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/byte_container_with_subtype.hpp), and [`ordered_map.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/ordered_map.hpp) define
  [`adl_serializer`](../api/adl_serializer/index.md),
  [`byte_container_with_subtype`](../api/byte_container_with_subtype/index.md), and
-  [`ordered_map`](../api/ordered_map.md).
+  [`ordered_map`](../api/ordered_map/index.md).

 Everything else lives in [`detail/`](https://github.com/nlohmann/json/tree/develop/include/nlohmann/detail) and namespace `nlohmann::detail`, which is not part of the public API. Paths
 below are relative to `include/nlohmann`.
@@ -97,7 +97,7 @@ is generated from these files with `make amalgamate` and must not be edited by h
 The library provides two specializations:

 - [`json`](../api/json.md) uses all default template arguments.
- [`ordered_json`](../api/ordered_json.md) uses [`ordered_map`](../api/ordered_map.md) as `ObjectType` to keep the
+- [`ordered_json`](../api/ordered_json.md) uses [`ordered_map`](../api/ordered_map/index.md) as `ObjectType` to keep the
  insertion order of object keys.

 The requirements on the template arguments are listed in
@@ -2,7 +2,8 @@

 This page summarizes the notable changes of every release and links to the relevant documentation.
 The **complete release notes** — including all changes, the download files, and their checksums — are
-published on the [GitHub releases page](https://github.com/nlohmann/json/releases).
+published on the [GitHub releases page](https://github.com/nlohmann/json/releases). For a raw,
+signature-level diff of the public API between releases, see [API Changes](api_changes.md).

 ## v3.12.0 (2025-04-11)

@@ -52,6 +52,7 @@ nav:
      - "FAQ": home/faq.md
      - home/exceptions.md
      - home/releases.md
+      - home/api_changes.md
      - home/design_goals.md
      - home/architecture.md
      - home/customers.md
@@ -119,6 +120,7 @@ nav:
          - 'begin': api/basic_json/begin.md
          - 'binary': api/basic_json/binary.md
          - 'binary_t': api/basic_json/binary_t.md
+          - 'bjdata_version_t': api/basic_json/bjdata_version_t.md
          - 'boolean_t': api/basic_json/boolean_t.md
          - 'cbegin': api/basic_json/cbegin.md
          - 'cbor_tag_handler_t': api/basic_json/cbor_tag_handler_t.md
@@ -157,6 +159,7 @@ nav:
          - 'get_to': api/basic_json/get_to.md
          - 'std::formatter&lt;basic_json&gt;': api/basic_json/std_formatter.md
          - 'std::hash&lt;basic_json&gt;': api/basic_json/std_hash.md
+          - 'initializer_list_t': api/basic_json/initializer_list_t.md
          - 'input_format_t': api/basic_json/input_format_t.md
          - 'insert': api/basic_json/insert.md
          - 'invalid_iterator': api/basic_json/invalid_iterator.md
@@ -175,6 +178,7 @@ nav:
          - 'is_structured': api/basic_json/is_structured.md
          - 'items': api/basic_json/items.md
          - 'json_base_class_t': api/basic_json/json_base_class_t.md
+          - 'json_sax_t': api/basic_json/json_sax_t.md
          - 'json_serializer': api/basic_json/json_serializer.md
          - 'max_size': api/basic_json/max_size.md
          - 'meta': api/basic_json/meta.md
@@ -232,9 +236,13 @@ nav:
          - 'Overview': api/byte_container_with_subtype/index.md
          - '(constructor)': api/byte_container_with_subtype/byte_container_with_subtype.md
          - 'clear_subtype': api/byte_container_with_subtype/clear_subtype.md
+          - 'container_type': api/byte_container_with_subtype/container_type.md
          - 'has_subtype': api/byte_container_with_subtype/has_subtype.md
+          - 'operator==': api/byte_container_with_subtype/operator_eq.md
+          - 'operator!=': api/byte_container_with_subtype/operator_ne.md
          - 'set_subtype': api/byte_container_with_subtype/set_subtype.md
          - 'subtype': api/byte_container_with_subtype/subtype.md
+          - 'subtype_type': api/byte_container_with_subtype/subtype_type.md
      - adl_serializer:
          - 'Overview': api/adl_serializer/index.md
          - 'from_json': api/adl_serializer/from_json.md
@@ -260,25 +268,46 @@ nav:
          - 'to_string': api/json_pointer/to_string.md
      - json_sax:
          - 'Overview': api/json_sax/index.md
+          - '(Constructor)': api/json_sax/json_sax.md
+          - '(Destructor)': api/json_sax/~json_sax.md
+          - 'operator=': api/json_sax/operator=.md
          - 'binary': api/json_sax/binary.md
+          - 'binary_t': api/json_sax/binary_t.md
          - 'boolean': api/json_sax/boolean.md
          - 'end_array': api/json_sax/end_array.md
          - 'end_object': api/json_sax/end_object.md
          - 'key': api/json_sax/key.md
          - 'null': api/json_sax/null.md
          - 'number_float': api/json_sax/number_float.md
+          - 'number_float_t': api/json_sax/number_float_t.md
          - 'number_integer': api/json_sax/number_integer.md
+          - 'number_integer_t': api/json_sax/number_integer_t.md
          - 'number_unsigned': api/json_sax/number_unsigned.md
+          - 'number_unsigned_t': api/json_sax/number_unsigned_t.md
          - 'parse_error': api/json_sax/parse_error.md
          - 'start_array': api/json_sax/start_array.md
          - 'start_object': api/json_sax/start_object.md
          - 'string': api/json_sax/string.md
+          - 'string_t': api/json_sax/string_t.md
      - 'operator<<(basic_json), operator<<(json_pointer)': api/operator_ltlt.md
      - 'operator>>(basic_json)': api/operator_gtgt.md
      - 'operator""_json': api/operator_literal_json.md
      - 'operator""_json_pointer': api/operator_literal_json_pointer.md
      - 'ordered_json': api/ordered_json.md
-      - 'ordered_map': api/ordered_map.md
+      - ordered_map:
+          - 'Overview': api/ordered_map/index.md
+          - '(Constructor)': api/ordered_map/ordered_map.md
+          - '(Destructor)': api/ordered_map/~ordered_map.md
+          - 'operator=': api/ordered_map/operator=.md
+          - 'at': api/ordered_map/at.md
+          - 'Container': api/ordered_map/Container.md
+          - 'count': api/ordered_map/count.md
+          - 'emplace': api/ordered_map/emplace.md
+          - 'erase': api/ordered_map/erase.md
+          - 'find': api/ordered_map/find.md
+          - 'insert': api/ordered_map/insert.md
+          - 'key_compare': api/ordered_map/key_compare.md
+          - 'operator[]': api/ordered_map/operator[].md
      - macros:
          - 'Overview': api/macros/index.md
          - 'JSON_ASSERT': api/macros/json_assert.md
@@ -22,7 +22,9 @@ template<typename BinaryType>
 class byte_container_with_subtype : public BinaryType
 {
  public:
+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/container_type/
    using container_type = BinaryType;
+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/subtype_type/
    using subtype_type = std::uint64_t;

    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/byte_container_with_subtype/
@@ -54,12 +56,14 @@ class byte_container_with_subtype : public BinaryType
        , m_has_subtype(true)
    {}

+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/operator_eq/
    bool operator==(const byte_container_with_subtype& rhs) const
    {
        return std::tie(static_cast<const BinaryType&>(*this), m_subtype, m_has_subtype) ==
               std::tie(static_cast<const BinaryType&>(rhs), rhs.m_subtype, rhs.m_has_subtype);
    }

+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/operator_ne/
    bool operator!=(const byte_container_with_subtype& rhs) const
    {
        return !(rhs == *this);
@@ -33,15 +33,21 @@ input.
 template<typename BasicJsonType>
 struct json_sax
 {
+    /// @sa https://json.nlohmann.me/api/json_sax/number_integer_t/
    using number_integer_t = typename BasicJsonType::number_integer_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/number_unsigned_t/
    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/number_float_t/
    using number_float_t = typename BasicJsonType::number_float_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/string_t/
    using string_t = typename BasicJsonType::string_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/binary_t/
    using binary_t = typename BasicJsonType::binary_t;

    /*!
    @brief a null value was read
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/null/
    */
    virtual bool null() = 0;

@@ -49,6 +55,7 @@ struct json_sax
    @brief a boolean value was read
    @param[in] val  boolean value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/boolean/
    */
    virtual bool boolean(bool val) = 0;

@@ -56,6 +63,7 @@ struct json_sax
    @brief an integer number was read
    @param[in] val  integer value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/number_integer/
    */
    virtual bool number_integer(number_integer_t val) = 0;

@@ -63,6 +71,7 @@ struct json_sax
    @brief an unsigned integer number was read
    @param[in] val  unsigned integer value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/number_unsigned/
    */
    virtual bool number_unsigned(number_unsigned_t val) = 0;

@@ -71,6 +80,7 @@ struct json_sax
    @param[in] val  floating-point value
    @param[in] s    raw token value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/number_float/
    */
    virtual bool number_float(number_float_t val, const string_t& s) = 0;

@@ -79,6 +89,7 @@ struct json_sax
    @param[in] val  string value
    @return whether parsing should proceed
    @note It is safe to move the passed string value.
+    @sa https://json.nlohmann.me/api/json_sax/string/
    */
    virtual bool string(string_t& val) = 0;

@@ -87,6 +98,7 @@ struct json_sax
    @param[in] val  binary value
    @return whether parsing should proceed
    @note It is safe to move the passed binary value.
+    @sa https://json.nlohmann.me/api/json_sax/binary/
    */
    virtual bool binary(binary_t& val) = 0;

@@ -95,6 +107,7 @@ struct json_sax
    @param[in] elements  number of object elements or -1 if unknown
    @return whether parsing should proceed
    @note binary formats may report the number of elements
+    @sa https://json.nlohmann.me/api/json_sax/start_object/
    */
    virtual bool start_object(std::size_t elements) = 0;

@@ -103,12 +116,14 @@ struct json_sax
    @param[in] val  object key
    @return whether parsing should proceed
    @note It is safe to move the passed string.
+    @sa https://json.nlohmann.me/api/json_sax/key/
    */
    virtual bool key(string_t& val) = 0;

    /*!
    @brief the end of an object was read
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/end_object/
    */
    virtual bool end_object() = 0;

@@ -117,12 +132,14 @@ struct json_sax
    @param[in] elements  number of array elements or -1 if unknown
    @return whether parsing should proceed
    @note binary formats may report the number of elements
+    @sa https://json.nlohmann.me/api/json_sax/start_array/
    */
    virtual bool start_array(std::size_t elements) = 0;

    /*!
    @brief the end of an array was read
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/end_array/
    */
    virtual bool end_array() = 0;

@@ -132,16 +149,23 @@ struct json_sax
    @param[in] last_token  the last read token
    @param[in] ex          an exception object describing the error
    @return whether parsing should proceed (must return false)
+    @sa https://json.nlohmann.me/api/json_sax/parse_error/
    */
    virtual bool parse_error(std::size_t position,
                             const std::string& last_token,
                             const detail::exception& ex) = 0;

+    /// @sa https://json.nlohmann.me/api/json_sax/json_sax/
    json_sax() = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/json_sax/
    json_sax(const json_sax&) = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/json_sax/
    json_sax(json_sax&&) noexcept = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/operator=/
    json_sax& operator=(const json_sax&) = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/operator=/
    json_sax& operator=(json_sax&&) noexcept = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/~json_sax/
    virtual ~json_sax() = default;
 };

@@ -206,6 +206,7 @@ class lexer : public lexer_base<BasicJsonType>
    explicit lexer(InputAdapterType&& adapter, bool ignore_comments_ = false, bool discard_number_values_ = false) noexcept
        : ia(std::move(adapter))
        , ignore_comments(ignore_comments_)
+        , decimal_point_char(static_cast<char_int_type>(get_decimal_point()))
        , discard_number_values(discard_number_values_)
    {}

@@ -221,7 +222,8 @@ class lexer : public lexer_base<BasicJsonType>
    // locales
    /////////////////////

-    /// return the decimal point of the current locale
+    /// return the locale-dependent decimal point
+    JSON_HEDLEY_PURE
    static char get_decimal_point() noexcept
    {
        const auto* loc = localeconv();
@@ -1090,10 +1092,9 @@ class lexer : public lexer_base<BasicJsonType>
            token_type::value_float if number could be successfully scanned,
            token_type::parse_error otherwise

-    @note The scanner is independent of the current locale: token_buffer
-          always holds `.`. Only the std::strtod fallback of convert_number()
-          depends on the locale, and it looks up the decimal point right
-          before converting (see convert_float_locale_aware()).
+    @note The scanner is independent of the current locale. Internally, the
+          locale's decimal point is used instead of `.` to work with the
+          locale-dependent converters.
    */
    token_type scan_number()  // lgtm [cpp/use-of-goto] `goto` is used in this function to implement the number-parsing state machine described above. By design, any finite input will eventually reach the "done" state or return token_type::parse_error. In each intermediate state, 1 byte of the input is appended to the token_buffer vector, and only the already initialized variables token_buffer, number_type, and error_message are manipulated.
    {
@@ -1182,7 +1183,7 @@ scan_number_zero:
        {
            case '.':
            {
-                add(current);
+                add(decimal_point_char);
                decimal_point_position = token_buffer.size() - 1;
                goto scan_number_decimal1;
            }
@@ -1219,7 +1220,7 @@ scan_number_any1:

            case '.':
            {
-                add(current);
+                add(decimal_point_char);
                decimal_point_position = token_buffer.size() - 1;
                goto scan_number_decimal1;
            }
@@ -1461,9 +1462,9 @@ scan_number_done:

        // Only a number below 1 can carry further insignificant zeros, and only
        // while the count stays at the limit does removing them change the
-        // answer - so this loop is skipped for all but a few tokens. The
-        // fraction is located through decimal_point_position rather than by
-        // searching '.'.
+        // answer - so this loop is skipped for all but a few tokens. Note
+        // token_buffer holds the locale's decimal point, so the fraction is
+        // located through decimal_point_position rather than by searching '.'.
        if (lead_zero != 0)
        {
            JSON_ASSERT(has_dot != 0); // an integer "0" cannot reach the limit
@@ -1481,8 +1482,8 @@ scan_number_done:
    @brief convert the number text in token_buffer to its value and token type

    The digit sequence in token_buffer has already been validated (by the
-    scan_number() state machine or by the contiguous fast path) and holds '.'
-    as decimal point, independent of the locale. Integers are parsed first and fall
+    scan_number() state machine or by the contiguous fast path) and holds the
+    locale decimal point in place of '.'. Integers are parsed first and fall
    back to floating point on overflow. This is shared so both scanners produce
    identical results.

@@ -1562,7 +1563,7 @@ scan_number_done:
        // integer conversion above overflowed. Prefer std::from_chars
        // (Eisel-Lemire, locale-independent, correctly rounded) when available;
        // otherwise the exact Clinger fast path (double only); otherwise the
-        // locale-aware strtof/strtod/strtold.
+        // locale-aware strtof/strtod.
        if (parse_float_from_chars(num_begin, num_end, value_float))
        {
            return token_type::value_float;
@@ -1571,75 +1572,26 @@ scan_number_done:
        // extra pass over the token's bytes, which otherwise shows up on
        // high-precision inputs such as canada.json
        if (mantissa_fits_clinger(mantissa_end)
-                && parse_float_fast(num_begin, num_end, value_float))
+                && parse_float_fast(num_begin, num_end, decimal_point_char, value_float))
        {
            return token_type::value_float;
        }

-        convert_float_locale_aware();
+        char* endptr = nullptr; // NOLINT(misc-const-correctness,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+        strtof(value_float, token_buffer.data(), &endptr);
+
+        // we checked the number format before
+        JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size());
+
        return token_type::value_float;
    }

-    /*!
-    @brief convert the float in token_buffer with strtof/strtod/strtold
-
-    These functions expect the decimal point of the *current* locale, so it is
-    looked up right before the conversion instead of once when the lexer is
-    constructed: a locale change in between (by a parser callback, a SAX
-    handler, or another thread) must not truncate the value (#5198). The
-    token has been validated before, so if the conversion stops early and the
-    decimal point changed in the meantime, the locale changed between the
-    lookup and the call, and the conversion is repeated with the new decimal
-    point. If the decimal point did not change, a retry cannot succeed: the
-    locale's decimal point is not a single character (e.g., the two-byte
-    U+066B of ar_EG.UTF-8 or fa_IR.UTF-8) and cannot be substituted in place.
-    The value strtod parsed up to that point is kept, as before this change.
-
-    Note that changing the locale in another thread *while* strtod runs is
-    undefined behavior of the C library, which this function cannot prevent.
-    */
-    void convert_float_locale_aware()
-    {
-        const bool has_dot = decimal_point_position != std::string::npos;
-        char decimal_point = get_decimal_point();
-        for (;;)
-        {
-            const bool substitute = has_dot && decimal_point != '.';
-            if (substitute)
-            {
-                token_buffer[decimal_point_position] = static_cast<typename string_t::value_type>(decimal_point);
-            }
-
-            char* endptr = nullptr; // NOLINT(misc-const-correctness,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
-            strtof(value_float, token_buffer.data(), &endptr);
-
-            if (substitute)
-            {
-                // get_string() hands the token to the SAX interface with '.'
-                token_buffer[decimal_point_position] = '.';
-            }
-
-            if (JSON_HEDLEY_LIKELY(endptr == token_buffer.data() + token_buffer.size()))
-            {
-                return;
-            }
-
-            // retry only if the locale changed; otherwise, this would loop forever
-            const char current_decimal_point = get_decimal_point();
-            if (current_decimal_point == decimal_point)
-            {
-                return;
-            }
-            decimal_point = current_decimal_point;
-        }
-    }
-
    /*!
    @brief contiguous fast path for scanning a number

    Parses the whole number token straight from the input buffer, avoiding the
    per-character get()/add() of scan_number(). On success it fills token_buffer
-    (as scan_number() does) and
+    (with the locale decimal point substituted, as scan_number() does) and
    returns the token type. On anything it does not fully recognize as a
    well-formed number it makes no state change and returns
    token_type::uninitialized, so the caller falls back to scan_number(), which
@@ -1755,11 +1707,16 @@ scan_number_done:
        }
 #endif

-        // materialize the token exactly as scan_number() would. reset() already
-        // cleared token_buffer, so append() fills it (assign() is avoided
-        // because custom string_t types need not provide it)
+        // materialize the token exactly as scan_number() would, substituting the
+        // locale decimal point so convert_number()'s strtof fallback stays valid.
+        // reset() already cleared token_buffer, so append() fills it (assign() is
+        // avoided because custom string_t types need not provide it)
        token_buffer.append(reinterpret_cast<const typename string_t::value_type*>(data), len);
-        decimal_point_position = dot_index;
+        if (dot_index != std::string::npos)
+        {
+            token_buffer[dot_index] = static_cast<typename string_t::value_type>(decimal_point_char);
+            decimal_point_position = dot_index;
+        }

        ia.bulk_skip(len - 1);
        position.chars_read_total += (len - 1);
@@ -2026,7 +1983,11 @@ scan_number_done:
    /// return current string value (implicitly resets the token; useful only once)
    string_t& get_string()
    {
-        // a number token holds '.' regardless of the locale (#4084)
+        // translate decimal points from locale back to '.' (#4084)
+        if (decimal_point_char != '.' && decimal_point_position != std::string::npos)
+        {
+            token_buffer[decimal_point_position] = '.';
+        }
        return token_buffer;
    }

@@ -2322,7 +2283,9 @@ scan_number_done:
    number_unsigned_t value_unsigned = 0;
    number_float_t value_float = 0;

-    /// the position of the decimal point in token_buffer
+    /// the decimal point
+    const char_int_type decimal_point_char = '.';
+    /// the position of the decimal point in the input
    std::size_t decimal_point_position = std::string::npos;

    /// whether the caller (e.g. accept()/json_sax_acceptor) only needs the
@@ -118,12 +118,14 @@ std::strtod. The parser only activates for number_float_t == double; float and
 long double keep the std::strtof/std::strtold paths (see the templated overload
 below).

-@param[in]  first  pointer to the first character of the number
-@param[in]  last   pointer past the last character
-@param[out] out    the parsed value on success
+@param[in]  first          pointer to the first character of the number
+@param[in]  last           pointer past the last character
+@param[in]  decimal_point  the (locale-dependent) decimal point character
+@param[out] out            the parsed value on success
@return true if the value was parsed exactly; false to fall back to strtod
 */
-inline bool parse_float_fast(const char* first, const char* last, double& out) noexcept
+template<typename DecimalPointType>
+bool parse_float_fast(const char* first, const char* last, DecimalPointType decimal_point, double& out) noexcept
 {
 #if defined(FLT_EVAL_METHOD) && FLT_EVAL_METHOD != 0
    // Clinger's fast path is only exact when double operations are evaluated in
@@ -134,6 +136,7 @@ inline bool parse_float_fast(const char* first, const char* last, double& out) n
    // std::from_chars / std::strtod path.
    static_cast<void>(first);
    static_cast<void>(last);
+    static_cast<void>(decimal_point);
    static_cast<void>(out);
    return false;
 #else
@@ -172,7 +175,7 @@ inline bool parse_float_fast(const char* first, const char* last, double& out) n
            ++num_digits;
            fractional_digits += static_cast<int>(seen_dot);
        }
-        else if (c == '.')
+        else if (static_cast<DecimalPointType>(c) == decimal_point)
        {
            if (JSON_HEDLEY_UNLIKELY(seen_dot))
            {
@@ -257,8 +260,8 @@ inline bool parse_float_fast(const char* first, const char* last, double& out) n
 }

 /// fast float path is only exact for `double`; decline for float/long double
-template<typename FloatType>
-bool parse_float_fast(const char* /*first*/, const char* /*last*/, FloatType& /*out*/) noexcept
+template<typename DecimalPointType, typename FloatType>
+bool parse_float_fast(const char* /*first*/, const char* /*last*/, DecimalPointType /*decimal_point*/, FloatType& /*out*/) noexcept
 {
    return false;
 }
@@ -270,7 +273,9 @@ std::from_chars is locale-independent, correctly rounded, and - via the
 Eisel-Lemire algorithm in modern standard libraries - much faster than strtod
 over the whole value range (not just the Clinger subset). It is used only when
 __cpp_lib_to_chars indicates full floating-point support and only when it
-consumes the entire token ([first, last)). An under-/overflow (result_out_of_range) also declines, so
+consumes the entire token ([first, last)); a partial parse means the buffer
+uses a non-'.' locale decimal point, in which case the caller falls back to the
+locale-aware path. An under-/overflow (result_out_of_range) also declines, so
 the caller's strtod fallback supplies the well-defined ±inf/0 result the parser
 expects (side-stepping the P4168 divergence between implementations).

@@ -56,6 +56,7 @@ class json_pointer

  public:
    // for backwards compatibility accept BasicJsonType
+    /// @sa https://json.nlohmann.me/api/json_pointer/string_t/
    using string_t = typename string_t_helper<RefStringType>::type;

    /// @brief create JSON pointer
@@ -202,22 +202,31 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    using serializer = ::nlohmann::detail::serializer<basic_json>;

  public:
+    /// @brief the type of the JSON value
+    /// @sa https://json.nlohmann.me/api/basic_json/value_t/
    using value_t = detail::value_t;
    /// JSON Pointer, see @ref nlohmann::json_pointer
    using json_pointer = ::nlohmann::json_pointer<StringType>;
    template<typename T, typename SFINAE>
    using json_serializer = JSONSerializer<T, SFINAE>;
    /// how to treat decoding errors
+    /// @sa https://json.nlohmann.me/api/basic_json/error_handler_t/
    using error_handler_t = detail::error_handler_t;
    /// how to treat CBOR tags
+    /// @sa https://json.nlohmann.me/api/basic_json/cbor_tag_handler_t/
    using cbor_tag_handler_t = detail::cbor_tag_handler_t;
    /// how to encode BJData
+    /// @sa https://json.nlohmann.me/api/basic_json/bjdata_version_t/
    using bjdata_version_t = detail::bjdata_version_t;
    /// helper type for initializer lists of basic_json values
+    /// @sa https://json.nlohmann.me/api/basic_json/initializer_list_t/
    using initializer_list_t = std::initializer_list<detail::json_ref<basic_json>>;

+    /// @brief the type of the SAX interface used to parse and serialize the JSON value
+    /// @sa https://json.nlohmann.me/api/basic_json/input_format_t/
    using input_format_t = detail::input_format_t;
    /// SAX interface type, see @ref nlohmann::json_sax
+    /// @sa https://json.nlohmann.me/api/basic_json/json_sax_t/
    using json_sax_t = json_sax<basic_json>;

    ////////////////
@@ -359,15 +368,19 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    /// the template arguments passed to class @ref basic_json.
    /// @{

+#if defined(JSON_HAS_CPP_14)
    /// @brief default object key comparator type
    /// The actual object key comparator type (@ref object_comparator_t) may be
    /// different.
    /// @sa https://json.nlohmann.me/api/basic_json/default_object_comparator_t/
-#if defined(JSON_HAS_CPP_14)
    // use of transparent comparator avoids unnecessary repeated construction of temporaries
    // in functions involving lookup by key with types other than object_t::key_type (aka. StringType)
    using default_object_comparator_t = std::less<>;
 #else
+    /// @brief default object key comparator type
+    /// The actual object key comparator type (@ref object_comparator_t) may be
+    /// different.
+    /// @sa https://json.nlohmann.me/api/basic_json/default_object_comparator_t/
    using default_object_comparator_t = std::less<StringType>;
 #endif

@@ -1913,6 +1926,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    // other constructors and destructor //
    ///////////////////////////////////////

+    /// @sa https://json.nlohmann.me/api/basic_json/basic_json/
    template<typename JsonRef,
             detail::enable_if_t<detail::conjunction<detail::is_json_ref<JsonRef>,
                                 std::is_same<typename JsonRef::value_type, basic_json>>::value, int> = 0 >
@@ -2496,6 +2510,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    @throw what @ref json_serializer<ValueType> `from_json()` method throws if conversion is required

    @since version 2.1.0
+
+    @sa https://json.nlohmann.me/api/basic_json/get/
    */
    template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>>
 #if defined(JSON_HAS_CPP_14)
@@ -2539,6 +2555,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    @sa see @ref get_ptr() for explicit pointer-member access

    @since version 1.0.0
+
+    @sa https://json.nlohmann.me/api/basic_json/get/
    */
    template<typename PointerType, typename std::enable_if<
                 std::is_pointer<PointerType>::value, int>::type = 0>
@@ -2565,6 +2583,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    // specialization to allow calling get_to with a basic_json value
    // see https://github.com/nlohmann/json/issues/2175
+    /// @sa https://json.nlohmann.me/api/basic_json/get_to/
    template<typename ValueType,
             detail::enable_if_t <
                 detail::is_basic_json<ValueType>::value,
@@ -2575,6 +2594,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return v;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/get_to/
    template <
        typename T, std::size_t N,
        typename Array = T (&)[N], // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
@@ -2639,6 +2659,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    @since version 1.0.0
    */
+    /// @sa https://json.nlohmann.me/api/basic_json/operator_ValueType/
    template < typename ValueType, typename std::enable_if <
                   detail::conjunction <
                       detail::negation<std::is_pointer<ValueType>>,
@@ -2911,12 +2932,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    // these two functions resolve a (const) char * ambiguity affecting Clang and MSVC
    // (they seemingly cannot be constrained to resolve the ambiguity)
+    /// @sa https://json.nlohmann.me/api/basic_json/operator[]/
    template<typename T>
    reference operator[](T* key)
    {
        return operator[](typename object_t::key_type(key));
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/operator[]/
    template<typename T>
    const_reference operator[](T* key) const
    {
@@ -3126,6 +3149,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        JSON_THROW(type_error::create(306, detail::concat("cannot use value() with ", type_name()), this));
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/value/
    template < class ValueType, class BasicJsonType, detail::enable_if_t <
                   detail::is_basic_json<BasicJsonType>::value
                   && detail::is_getable<basic_json_t, ValueType>::value
@@ -3136,6 +3160,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return value(ptr.convert(), default_value);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/value/
    template < class ValueType, class BasicJsonType, class ReturnType = typename value_return_type<ValueType>::type,
               detail::enable_if_t <
                   detail::is_basic_json<BasicJsonType>::value
@@ -3515,6 +3540,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.contains(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/contains/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
@@ -4934,6 +4960,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/parse/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, parse(ptr, ptr + len))
    static basic_json parse(detail::span_input_adapter&& i,
@@ -4970,6 +4997,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return parser(detail::input_adapter(std::move(first), std::move(last)), nullptr, false, ignore_comments, ignore_trailing_commas, true).accept(true);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/accept/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, accept(ptr, ptr + len))
    static bool accept(detail::span_input_adapter&& i,
@@ -5353,6 +5381,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_cbor/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
@@ -5364,6 +5393,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_cbor(ptr, ptr + len, strict, allow_exceptions, tag_handler);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_cbor/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
    static basic_json from_cbor(detail::span_input_adapter&& i,
@@ -5419,6 +5449,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_msgpack/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
@@ -5429,6 +5460,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_msgpack(ptr, ptr + len, strict, allow_exceptions);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_msgpack/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
    static basic_json from_msgpack(detail::span_input_adapter&& i,
@@ -5483,6 +5515,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_ubjson/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
@@ -5493,6 +5526,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_ubjson(ptr, ptr + len, strict, allow_exceptions);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_ubjson/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
    static basic_json from_ubjson(detail::span_input_adapter&& i,
@@ -5621,6 +5655,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_bson/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
@@ -5631,6 +5666,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_bson(ptr, ptr + len, strict, allow_exceptions);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_bson/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
    static basic_json from_bson(detail::span_input_adapter&& i,
@@ -5663,6 +5699,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_unchecked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr)
@@ -5677,6 +5714,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_unchecked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    const_reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
@@ -5691,6 +5729,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_checked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/at/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr)
@@ -5705,6 +5744,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_checked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/at/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    const_reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
@@ -30,30 +30,41 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
 {
    using key_type = Key;
    using mapped_type = T;
+    /// @sa https://json.nlohmann.me/api/ordered_map/Container/
    using Container = std::vector<std::pair<const Key, T>, Allocator>;
    using iterator = typename Container::iterator;
    using const_iterator = typename Container::const_iterator;
    using size_type = typename Container::size_type;
    using value_type = typename Container::value_type;
 #ifdef JSON_HAS_CPP_14
+    /// @sa https://json.nlohmann.me/api/ordered_map/key_compare/
    using key_compare = std::equal_to<>;
 #else
+    /// @sa https://json.nlohmann.me/api/ordered_map/key_compare/
    using key_compare = std::equal_to<Key>;
 #endif

    // Explicit constructors instead of `using Container::Container`
    // otherwise older compilers choke on it (GCC <= 5.5, xcode <= 9.4)
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map() noexcept(noexcept(Container())) : Container{} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    explicit ordered_map(const Allocator& alloc) noexcept(noexcept(Container(alloc))) : Container{alloc} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    template <class It>
    ordered_map(It first, It last, const Allocator& alloc = Allocator())
        : Container{first, last, alloc} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map(std::initializer_list<value_type> init, const Allocator& alloc = Allocator() )
        : Container{init, alloc} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map(const ordered_map&) = default;
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map(ordered_map&&) noexcept(std::is_nothrow_move_constructible<Container>::value) = default;
+    /// @sa https://json.nlohmann.me/api/ordered_map/~ordered_map/
    ~ordered_map() = default;

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator=/
    ordered_map& operator=(const ordered_map& other)
    {
        if (this != &other)
@@ -64,12 +75,14 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return *this;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator=/
    ordered_map& operator=(ordered_map&& other) noexcept(std::is_nothrow_move_assignable<Container>::value)
    {
        Container::operator=(std::move(static_cast<Container&>(other)));
        return *this;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/emplace/
    std::pair<iterator, bool> emplace(const key_type& key, T&& t)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -83,6 +96,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return {std::prev(this->end()), true};
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/emplace/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    std::pair<iterator, bool> emplace(KeyType && key, T && t)
@@ -98,11 +112,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return {std::prev(this->end()), true};
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    T& operator[](const key_type& key)
    {
        return emplace(key, T{}).first->second;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    T & operator[](KeyType && key)
@@ -110,11 +126,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return emplace(std::forward<KeyType>(key), T{}).first->second;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    const T& operator[](const key_type& key) const
    {
        return at(key);
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    const T & operator[](KeyType && key) const
@@ -122,6 +140,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return at(std::forward<KeyType>(key));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    T& at(const key_type& key)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -135,6 +154,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    T & at(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -150,6 +170,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    const T& at(const key_type& key) const
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -163,6 +184,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    const T & at(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -178,6 +200,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    size_type erase(const key_type& key)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -197,6 +220,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    size_type erase(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -218,11 +242,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    iterator erase(iterator pos)
    {
        return erase(pos, std::next(pos));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    iterator erase(iterator first, iterator last)
    {
        if (first == last)
@@ -276,6 +302,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::begin() + offset;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/count/
    size_type count(const key_type& key) const
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -288,6 +315,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/count/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    size_type count(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -302,6 +330,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    iterator find(const key_type& key)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -314,6 +343,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    iterator find(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -328,6 +358,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    const_iterator find(const key_type& key) const
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -340,6 +371,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    const_iterator find(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -354,11 +386,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/insert/
    std::pair<iterator, bool> insert( value_type&& value )
    {
        return emplace(value.first, std::move(value.second));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/insert/
    std::pair<iterator, bool> insert( const value_type& value )
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -376,6 +410,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
    using require_input_iter = typename std::enable_if<std::is_convertible<typename std::iterator_traits<InputIt>::iterator_category,
        std::input_iterator_tag>::value>::type;

+    /// @sa https://json.nlohmann.me/api/ordered_map/insert/
    template<typename InputIt, typename = require_input_iter<InputIt>>
    void insert(InputIt first, InputIt last)
    {
@@ -7154,7 +7154,9 @@ template<typename BinaryType>
 class byte_container_with_subtype : public BinaryType
 {
  public:
+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/container_type/
    using container_type = BinaryType;
+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/subtype_type/
    using subtype_type = std::uint64_t;

    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/byte_container_with_subtype/
@@ -7186,12 +7188,14 @@ class byte_container_with_subtype : public BinaryType
        , m_has_subtype(true)
    {}

+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/operator_eq/
    bool operator==(const byte_container_with_subtype& rhs) const
    {
        return std::tie(static_cast<const BinaryType&>(*this), m_subtype, m_has_subtype) ==
               std::tie(static_cast<const BinaryType&>(rhs), rhs.m_subtype, rhs.m_has_subtype);
    }

+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/operator_ne/
    bool operator!=(const byte_container_with_subtype& rhs) const
    {
        return !(rhs == *this);
@@ -8605,12 +8609,14 @@ std::strtod. The parser only activates for number_float_t == double; float and
 long double keep the std::strtof/std::strtold paths (see the templated overload
 below).

-@param[in]  first  pointer to the first character of the number
-@param[in]  last   pointer past the last character
-@param[out] out    the parsed value on success
+@param[in]  first          pointer to the first character of the number
+@param[in]  last           pointer past the last character
+@param[in]  decimal_point  the (locale-dependent) decimal point character
+@param[out] out            the parsed value on success
@return true if the value was parsed exactly; false to fall back to strtod
 */
-inline bool parse_float_fast(const char* first, const char* last, double& out) noexcept
+template<typename DecimalPointType>
+bool parse_float_fast(const char* first, const char* last, DecimalPointType decimal_point, double& out) noexcept
 {
 #if defined(FLT_EVAL_METHOD) && FLT_EVAL_METHOD != 0
    // Clinger's fast path is only exact when double operations are evaluated in
@@ -8621,6 +8627,7 @@ inline bool parse_float_fast(const char* first, const char* last, double& out) n
    // std::from_chars / std::strtod path.
    static_cast<void>(first);
    static_cast<void>(last);
+    static_cast<void>(decimal_point);
    static_cast<void>(out);
    return false;
 #else
@@ -8659,7 +8666,7 @@ inline bool parse_float_fast(const char* first, const char* last, double& out) n
            ++num_digits;
            fractional_digits += static_cast<int>(seen_dot);
        }
-        else if (c == '.')
+        else if (static_cast<DecimalPointType>(c) == decimal_point)
        {
            if (JSON_HEDLEY_UNLIKELY(seen_dot))
            {
@@ -8744,8 +8751,8 @@ inline bool parse_float_fast(const char* first, const char* last, double& out) n
 }

 /// fast float path is only exact for `double`; decline for float/long double
-template<typename FloatType>
-bool parse_float_fast(const char* /*first*/, const char* /*last*/, FloatType& /*out*/) noexcept
+template<typename DecimalPointType, typename FloatType>
+bool parse_float_fast(const char* /*first*/, const char* /*last*/, DecimalPointType /*decimal_point*/, FloatType& /*out*/) noexcept
 {
    return false;
 }
@@ -8757,7 +8764,9 @@ std::from_chars is locale-independent, correctly rounded, and - via the
 Eisel-Lemire algorithm in modern standard libraries - much faster than strtod
 over the whole value range (not just the Clinger subset). It is used only when
 __cpp_lib_to_chars indicates full floating-point support and only when it
-consumes the entire token ([first, last)). An under-/overflow (result_out_of_range) also declines, so
+consumes the entire token ([first, last)); a partial parse means the buffer
+uses a non-'.' locale decimal point, in which case the caller falls back to the
+locale-aware path. An under-/overflow (result_out_of_range) also declines, so
 the caller's strtod fallback supplies the well-defined ±inf/0 result the parser
 expects (side-stepping the P4168 divergence between implementations).

@@ -9298,6 +9307,7 @@ class lexer : public lexer_base<BasicJsonType>
    explicit lexer(InputAdapterType&& adapter, bool ignore_comments_ = false, bool discard_number_values_ = false) noexcept
        : ia(std::move(adapter))
        , ignore_comments(ignore_comments_)
+        , decimal_point_char(static_cast<char_int_type>(get_decimal_point()))
        , discard_number_values(discard_number_values_)
    {}

@@ -9313,7 +9323,8 @@ class lexer : public lexer_base<BasicJsonType>
    // locales
    /////////////////////

-    /// return the decimal point of the current locale
+    /// return the locale-dependent decimal point
+    JSON_HEDLEY_PURE
    static char get_decimal_point() noexcept
    {
        const auto* loc = localeconv();
@@ -10182,10 +10193,9 @@ class lexer : public lexer_base<BasicJsonType>
            token_type::value_float if number could be successfully scanned,
            token_type::parse_error otherwise

-    @note The scanner is independent of the current locale: token_buffer
-          always holds `.`. Only the std::strtod fallback of convert_number()
-          depends on the locale, and it looks up the decimal point right
-          before converting (see convert_float_locale_aware()).
+    @note The scanner is independent of the current locale. Internally, the
+          locale's decimal point is used instead of `.` to work with the
+          locale-dependent converters.
    */
    token_type scan_number()  // lgtm [cpp/use-of-goto] `goto` is used in this function to implement the number-parsing state machine described above. By design, any finite input will eventually reach the "done" state or return token_type::parse_error. In each intermediate state, 1 byte of the input is appended to the token_buffer vector, and only the already initialized variables token_buffer, number_type, and error_message are manipulated.
    {
@@ -10274,7 +10284,7 @@ scan_number_zero:
        {
            case '.':
            {
-                add(current);
+                add(decimal_point_char);
                decimal_point_position = token_buffer.size() - 1;
                goto scan_number_decimal1;
            }
@@ -10311,7 +10321,7 @@ scan_number_any1:

            case '.':
            {
-                add(current);
+                add(decimal_point_char);
                decimal_point_position = token_buffer.size() - 1;
                goto scan_number_decimal1;
            }
@@ -10553,9 +10563,9 @@ scan_number_done:

        // Only a number below 1 can carry further insignificant zeros, and only
        // while the count stays at the limit does removing them change the
-        // answer - so this loop is skipped for all but a few tokens. The
-        // fraction is located through decimal_point_position rather than by
-        // searching '.'.
+        // answer - so this loop is skipped for all but a few tokens. Note
+        // token_buffer holds the locale's decimal point, so the fraction is
+        // located through decimal_point_position rather than by searching '.'.
        if (lead_zero != 0)
        {
            JSON_ASSERT(has_dot != 0); // an integer "0" cannot reach the limit
@@ -10573,8 +10583,8 @@ scan_number_done:
    @brief convert the number text in token_buffer to its value and token type

    The digit sequence in token_buffer has already been validated (by the
-    scan_number() state machine or by the contiguous fast path) and holds '.'
-    as decimal point, independent of the locale. Integers are parsed first and fall
+    scan_number() state machine or by the contiguous fast path) and holds the
+    locale decimal point in place of '.'. Integers are parsed first and fall
    back to floating point on overflow. This is shared so both scanners produce
    identical results.

@@ -10654,7 +10664,7 @@ scan_number_done:
        // integer conversion above overflowed. Prefer std::from_chars
        // (Eisel-Lemire, locale-independent, correctly rounded) when available;
        // otherwise the exact Clinger fast path (double only); otherwise the
-        // locale-aware strtof/strtod/strtold.
+        // locale-aware strtof/strtod.
        if (parse_float_from_chars(num_begin, num_end, value_float))
        {
            return token_type::value_float;
@@ -10663,75 +10673,26 @@ scan_number_done:
        // extra pass over the token's bytes, which otherwise shows up on
        // high-precision inputs such as canada.json
        if (mantissa_fits_clinger(mantissa_end)
-                && parse_float_fast(num_begin, num_end, value_float))
+                && parse_float_fast(num_begin, num_end, decimal_point_char, value_float))
        {
            return token_type::value_float;
        }

-        convert_float_locale_aware();
+        char* endptr = nullptr; // NOLINT(misc-const-correctness,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+        strtof(value_float, token_buffer.data(), &endptr);
+
+        // we checked the number format before
+        JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size());
+
        return token_type::value_float;
    }

-    /*!
-    @brief convert the float in token_buffer with strtof/strtod/strtold
-
-    These functions expect the decimal point of the *current* locale, so it is
-    looked up right before the conversion instead of once when the lexer is
-    constructed: a locale change in between (by a parser callback, a SAX
-    handler, or another thread) must not truncate the value (#5198). The
-    token has been validated before, so if the conversion stops early and the
-    decimal point changed in the meantime, the locale changed between the
-    lookup and the call, and the conversion is repeated with the new decimal
-    point. If the decimal point did not change, a retry cannot succeed: the
-    locale's decimal point is not a single character (e.g., the two-byte
-    U+066B of ar_EG.UTF-8 or fa_IR.UTF-8) and cannot be substituted in place.
-    The value strtod parsed up to that point is kept, as before this change.
-
-    Note that changing the locale in another thread *while* strtod runs is
-    undefined behavior of the C library, which this function cannot prevent.
-    */
-    void convert_float_locale_aware()
-    {
-        const bool has_dot = decimal_point_position != std::string::npos;
-        char decimal_point = get_decimal_point();
-        for (;;)
-        {
-            const bool substitute = has_dot && decimal_point != '.';
-            if (substitute)
-            {
-                token_buffer[decimal_point_position] = static_cast<typename string_t::value_type>(decimal_point);
-            }
-
-            char* endptr = nullptr; // NOLINT(misc-const-correctness,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
-            strtof(value_float, token_buffer.data(), &endptr);
-
-            if (substitute)
-            {
-                // get_string() hands the token to the SAX interface with '.'
-                token_buffer[decimal_point_position] = '.';
-            }
-
-            if (JSON_HEDLEY_LIKELY(endptr == token_buffer.data() + token_buffer.size()))
-            {
-                return;
-            }
-
-            // retry only if the locale changed; otherwise, this would loop forever
-            const char current_decimal_point = get_decimal_point();
-            if (current_decimal_point == decimal_point)
-            {
-                return;
-            }
-            decimal_point = current_decimal_point;
-        }
-    }
-
    /*!
    @brief contiguous fast path for scanning a number

    Parses the whole number token straight from the input buffer, avoiding the
    per-character get()/add() of scan_number(). On success it fills token_buffer
-    (as scan_number() does) and
+    (with the locale decimal point substituted, as scan_number() does) and
    returns the token type. On anything it does not fully recognize as a
    well-formed number it makes no state change and returns
    token_type::uninitialized, so the caller falls back to scan_number(), which
@@ -10847,11 +10808,16 @@ scan_number_done:
        }
 #endif

-        // materialize the token exactly as scan_number() would. reset() already
-        // cleared token_buffer, so append() fills it (assign() is avoided
-        // because custom string_t types need not provide it)
+        // materialize the token exactly as scan_number() would, substituting the
+        // locale decimal point so convert_number()'s strtof fallback stays valid.
+        // reset() already cleared token_buffer, so append() fills it (assign() is
+        // avoided because custom string_t types need not provide it)
        token_buffer.append(reinterpret_cast<const typename string_t::value_type*>(data), len);
-        decimal_point_position = dot_index;
+        if (dot_index != std::string::npos)
+        {
+            token_buffer[dot_index] = static_cast<typename string_t::value_type>(decimal_point_char);
+            decimal_point_position = dot_index;
+        }

        ia.bulk_skip(len - 1);
        position.chars_read_total += (len - 1);
@@ -11118,7 +11084,11 @@ scan_number_done:
    /// return current string value (implicitly resets the token; useful only once)
    string_t& get_string()
    {
-        // a number token holds '.' regardless of the locale (#4084)
+        // translate decimal points from locale back to '.' (#4084)
+        if (decimal_point_char != '.' && decimal_point_position != std::string::npos)
+        {
+            token_buffer[decimal_point_position] = '.';
+        }
        return token_buffer;
    }

@@ -11414,7 +11384,9 @@ scan_number_done:
    number_unsigned_t value_unsigned = 0;
    number_float_t value_float = 0;

-    /// the position of the decimal point in token_buffer
+    /// the decimal point
+    const char_int_type decimal_point_char = '.';
+    /// the position of the decimal point in the input
    std::size_t decimal_point_position = std::string::npos;

    /// whether the caller (e.g. accept()/json_sax_acceptor) only needs the
@@ -11447,15 +11419,21 @@ input.
 template<typename BasicJsonType>
 struct json_sax
 {
+    /// @sa https://json.nlohmann.me/api/json_sax/number_integer_t/
    using number_integer_t = typename BasicJsonType::number_integer_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/number_unsigned_t/
    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/number_float_t/
    using number_float_t = typename BasicJsonType::number_float_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/string_t/
    using string_t = typename BasicJsonType::string_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/binary_t/
    using binary_t = typename BasicJsonType::binary_t;

    /*!
    @brief a null value was read
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/null/
    */
    virtual bool null() = 0;

@@ -11463,6 +11441,7 @@ struct json_sax
    @brief a boolean value was read
    @param[in] val  boolean value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/boolean/
    */
    virtual bool boolean(bool val) = 0;

@@ -11470,6 +11449,7 @@ struct json_sax
    @brief an integer number was read
    @param[in] val  integer value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/number_integer/
    */
    virtual bool number_integer(number_integer_t val) = 0;

@@ -11477,6 +11457,7 @@ struct json_sax
    @brief an unsigned integer number was read
    @param[in] val  unsigned integer value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/number_unsigned/
    */
    virtual bool number_unsigned(number_unsigned_t val) = 0;

@@ -11485,6 +11466,7 @@ struct json_sax
    @param[in] val  floating-point value
    @param[in] s    raw token value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/number_float/
    */
    virtual bool number_float(number_float_t val, const string_t& s) = 0;

@@ -11493,6 +11475,7 @@ struct json_sax
    @param[in] val  string value
    @return whether parsing should proceed
    @note It is safe to move the passed string value.
+    @sa https://json.nlohmann.me/api/json_sax/string/
    */
    virtual bool string(string_t& val) = 0;

@@ -11501,6 +11484,7 @@ struct json_sax
    @param[in] val  binary value
    @return whether parsing should proceed
    @note It is safe to move the passed binary value.
+    @sa https://json.nlohmann.me/api/json_sax/binary/
    */
    virtual bool binary(binary_t& val) = 0;

@@ -11509,6 +11493,7 @@ struct json_sax
    @param[in] elements  number of object elements or -1 if unknown
    @return whether parsing should proceed
    @note binary formats may report the number of elements
+    @sa https://json.nlohmann.me/api/json_sax/start_object/
    */
    virtual bool start_object(std::size_t elements) = 0;

@@ -11517,12 +11502,14 @@ struct json_sax
    @param[in] val  object key
    @return whether parsing should proceed
    @note It is safe to move the passed string.
+    @sa https://json.nlohmann.me/api/json_sax/key/
    */
    virtual bool key(string_t& val) = 0;

    /*!
    @brief the end of an object was read
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/end_object/
    */
    virtual bool end_object() = 0;

@@ -11531,12 +11518,14 @@ struct json_sax
    @param[in] elements  number of array elements or -1 if unknown
    @return whether parsing should proceed
    @note binary formats may report the number of elements
+    @sa https://json.nlohmann.me/api/json_sax/start_array/
    */
    virtual bool start_array(std::size_t elements) = 0;

    /*!
    @brief the end of an array was read
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/end_array/
    */
    virtual bool end_array() = 0;

@@ -11546,16 +11535,23 @@ struct json_sax
    @param[in] last_token  the last read token
    @param[in] ex          an exception object describing the error
    @return whether parsing should proceed (must return false)
+    @sa https://json.nlohmann.me/api/json_sax/parse_error/
    */
    virtual bool parse_error(std::size_t position,
                             const std::string& last_token,
                             const detail::exception& ex) = 0;

+    /// @sa https://json.nlohmann.me/api/json_sax/json_sax/
    json_sax() = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/json_sax/
    json_sax(const json_sax&) = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/json_sax/
    json_sax(json_sax&&) noexcept = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/operator=/
    json_sax& operator=(const json_sax&) = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/operator=/
    json_sax& operator=(json_sax&&) noexcept = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/~json_sax/
    virtual ~json_sax() = default;
 };

@@ -18732,6 +18728,7 @@ class json_pointer

  public:
    // for backwards compatibility accept BasicJsonType
+    /// @sa https://json.nlohmann.me/api/json_pointer/string_t/
    using string_t = typename string_t_helper<RefStringType>::type;

    /// @brief create JSON pointer
@@ -25626,30 +25623,41 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
 {
    using key_type = Key;
    using mapped_type = T;
+    /// @sa https://json.nlohmann.me/api/ordered_map/Container/
    using Container = std::vector<std::pair<const Key, T>, Allocator>;
    using iterator = typename Container::iterator;
    using const_iterator = typename Container::const_iterator;
    using size_type = typename Container::size_type;
    using value_type = typename Container::value_type;
 #ifdef JSON_HAS_CPP_14
+    /// @sa https://json.nlohmann.me/api/ordered_map/key_compare/
    using key_compare = std::equal_to<>;
 #else
+    /// @sa https://json.nlohmann.me/api/ordered_map/key_compare/
    using key_compare = std::equal_to<Key>;
 #endif

    // Explicit constructors instead of `using Container::Container`
    // otherwise older compilers choke on it (GCC <= 5.5, xcode <= 9.4)
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map() noexcept(noexcept(Container())) : Container{} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    explicit ordered_map(const Allocator& alloc) noexcept(noexcept(Container(alloc))) : Container{alloc} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    template <class It>
    ordered_map(It first, It last, const Allocator& alloc = Allocator())
        : Container{first, last, alloc} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map(std::initializer_list<value_type> init, const Allocator& alloc = Allocator() )
        : Container{init, alloc} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map(const ordered_map&) = default;
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map(ordered_map&&) noexcept(std::is_nothrow_move_constructible<Container>::value) = default;
+    /// @sa https://json.nlohmann.me/api/ordered_map/~ordered_map/
    ~ordered_map() = default;

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator=/
    ordered_map& operator=(const ordered_map& other)
    {
        if (this != &other)
@@ -25660,12 +25668,14 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return *this;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator=/
    ordered_map& operator=(ordered_map&& other) noexcept(std::is_nothrow_move_assignable<Container>::value)
    {
        Container::operator=(std::move(static_cast<Container&>(other)));
        return *this;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/emplace/
    std::pair<iterator, bool> emplace(const key_type& key, T&& t)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -25679,6 +25689,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return {std::prev(this->end()), true};
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/emplace/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    std::pair<iterator, bool> emplace(KeyType && key, T && t)
@@ -25694,11 +25705,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return {std::prev(this->end()), true};
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    T& operator[](const key_type& key)
    {
        return emplace(key, T{}).first->second;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    T & operator[](KeyType && key)
@@ -25706,11 +25719,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return emplace(std::forward<KeyType>(key), T{}).first->second;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    const T& operator[](const key_type& key) const
    {
        return at(key);
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    const T & operator[](KeyType && key) const
@@ -25718,6 +25733,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return at(std::forward<KeyType>(key));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    T& at(const key_type& key)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -25731,6 +25747,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    T & at(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -25746,6 +25763,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    const T& at(const key_type& key) const
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -25759,6 +25777,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    const T & at(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -25774,6 +25793,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    size_type erase(const key_type& key)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -25793,6 +25813,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    size_type erase(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -25814,11 +25835,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    iterator erase(iterator pos)
    {
        return erase(pos, std::next(pos));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    iterator erase(iterator first, iterator last)
    {
        if (first == last)
@@ -25872,6 +25895,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::begin() + offset;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/count/
    size_type count(const key_type& key) const
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -25884,6 +25908,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/count/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    size_type count(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -25898,6 +25923,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    iterator find(const key_type& key)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -25910,6 +25936,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    iterator find(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -25924,6 +25951,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    const_iterator find(const key_type& key) const
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -25936,6 +25964,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    const_iterator find(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -25950,11 +25979,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/insert/
    std::pair<iterator, bool> insert( value_type&& value )
    {
        return emplace(value.first, std::move(value.second));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/insert/
    std::pair<iterator, bool> insert( const value_type& value )
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -25972,6 +26003,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
    using require_input_iter = typename std::enable_if<std::is_convertible<typename std::iterator_traits<InputIt>::iterator_category,
        std::input_iterator_tag>::value>::type;

+    /// @sa https://json.nlohmann.me/api/ordered_map/insert/
    template<typename InputIt, typename = require_input_iter<InputIt>>
    void insert(InputIt first, InputIt last)
    {
@@ -26117,22 +26149,31 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    using serializer = ::nlohmann::detail::serializer<basic_json>;

  public:
+    /// @brief the type of the JSON value
+    /// @sa https://json.nlohmann.me/api/basic_json/value_t/
    using value_t = detail::value_t;
    /// JSON Pointer, see @ref nlohmann::json_pointer
    using json_pointer = ::nlohmann::json_pointer<StringType>;
    template<typename T, typename SFINAE>
    using json_serializer = JSONSerializer<T, SFINAE>;
    /// how to treat decoding errors
+    /// @sa https://json.nlohmann.me/api/basic_json/error_handler_t/
    using error_handler_t = detail::error_handler_t;
    /// how to treat CBOR tags
+    /// @sa https://json.nlohmann.me/api/basic_json/cbor_tag_handler_t/
    using cbor_tag_handler_t = detail::cbor_tag_handler_t;
    /// how to encode BJData
+    /// @sa https://json.nlohmann.me/api/basic_json/bjdata_version_t/
    using bjdata_version_t = detail::bjdata_version_t;
    /// helper type for initializer lists of basic_json values
+    /// @sa https://json.nlohmann.me/api/basic_json/initializer_list_t/
    using initializer_list_t = std::initializer_list<detail::json_ref<basic_json>>;

+    /// @brief the type of the SAX interface used to parse and serialize the JSON value
+    /// @sa https://json.nlohmann.me/api/basic_json/input_format_t/
    using input_format_t = detail::input_format_t;
    /// SAX interface type, see @ref nlohmann::json_sax
+    /// @sa https://json.nlohmann.me/api/basic_json/json_sax_t/
    using json_sax_t = json_sax<basic_json>;

    ////////////////
@@ -26274,15 +26315,19 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    /// the template arguments passed to class @ref basic_json.
    /// @{

+#if defined(JSON_HAS_CPP_14)
    /// @brief default object key comparator type
    /// The actual object key comparator type (@ref object_comparator_t) may be
    /// different.
    /// @sa https://json.nlohmann.me/api/basic_json/default_object_comparator_t/
-#if defined(JSON_HAS_CPP_14)
    // use of transparent comparator avoids unnecessary repeated construction of temporaries
    // in functions involving lookup by key with types other than object_t::key_type (aka. StringType)
    using default_object_comparator_t = std::less<>;
 #else
+    /// @brief default object key comparator type
+    /// The actual object key comparator type (@ref object_comparator_t) may be
+    /// different.
+    /// @sa https://json.nlohmann.me/api/basic_json/default_object_comparator_t/
    using default_object_comparator_t = std::less<StringType>;
 #endif

@@ -27828,6 +27873,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    // other constructors and destructor //
    ///////////////////////////////////////

+    /// @sa https://json.nlohmann.me/api/basic_json/basic_json/
    template<typename JsonRef,
             detail::enable_if_t<detail::conjunction<detail::is_json_ref<JsonRef>,
                                 std::is_same<typename JsonRef::value_type, basic_json>>::value, int> = 0 >
@@ -28411,6 +28457,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    @throw what @ref json_serializer<ValueType> `from_json()` method throws if conversion is required

    @since version 2.1.0
+
+    @sa https://json.nlohmann.me/api/basic_json/get/
    */
    template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>>
 #if defined(JSON_HAS_CPP_14)
@@ -28454,6 +28502,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    @sa see @ref get_ptr() for explicit pointer-member access

    @since version 1.0.0
+
+    @sa https://json.nlohmann.me/api/basic_json/get/
    */
    template<typename PointerType, typename std::enable_if<
                 std::is_pointer<PointerType>::value, int>::type = 0>
@@ -28480,6 +28530,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    // specialization to allow calling get_to with a basic_json value
    // see https://github.com/nlohmann/json/issues/2175
+    /// @sa https://json.nlohmann.me/api/basic_json/get_to/
    template<typename ValueType,
             detail::enable_if_t <
                 detail::is_basic_json<ValueType>::value,
@@ -28490,6 +28541,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return v;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/get_to/
    template <
        typename T, std::size_t N,
        typename Array = T (&)[N], // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
@@ -28554,6 +28606,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    @since version 1.0.0
    */
+    /// @sa https://json.nlohmann.me/api/basic_json/operator_ValueType/
    template < typename ValueType, typename std::enable_if <
                   detail::conjunction <
                       detail::negation<std::is_pointer<ValueType>>,
@@ -28826,12 +28879,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    // these two functions resolve a (const) char * ambiguity affecting Clang and MSVC
    // (they seemingly cannot be constrained to resolve the ambiguity)
+    /// @sa https://json.nlohmann.me/api/basic_json/operator[]/
    template<typename T>
    reference operator[](T* key)
    {
        return operator[](typename object_t::key_type(key));
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/operator[]/
    template<typename T>
    const_reference operator[](T* key) const
    {
@@ -29041,6 +29096,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        JSON_THROW(type_error::create(306, detail::concat("cannot use value() with ", type_name()), this));
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/value/
    template < class ValueType, class BasicJsonType, detail::enable_if_t <
                   detail::is_basic_json<BasicJsonType>::value
                   && detail::is_getable<basic_json_t, ValueType>::value
@@ -29051,6 +29107,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return value(ptr.convert(), default_value);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/value/
    template < class ValueType, class BasicJsonType, class ReturnType = typename value_return_type<ValueType>::type,
               detail::enable_if_t <
                   detail::is_basic_json<BasicJsonType>::value
@@ -29430,6 +29487,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.contains(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/contains/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
@@ -30849,6 +30907,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/parse/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, parse(ptr, ptr + len))
    static basic_json parse(detail::span_input_adapter&& i,
@@ -30885,6 +30944,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return parser(detail::input_adapter(std::move(first), std::move(last)), nullptr, false, ignore_comments, ignore_trailing_commas, true).accept(true);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/accept/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, accept(ptr, ptr + len))
    static bool accept(detail::span_input_adapter&& i,
@@ -31268,6 +31328,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_cbor/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
@@ -31279,6 +31340,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_cbor(ptr, ptr + len, strict, allow_exceptions, tag_handler);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_cbor/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
    static basic_json from_cbor(detail::span_input_adapter&& i,
@@ -31334,6 +31396,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_msgpack/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
@@ -31344,6 +31407,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_msgpack(ptr, ptr + len, strict, allow_exceptions);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_msgpack/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
    static basic_json from_msgpack(detail::span_input_adapter&& i,
@@ -31398,6 +31462,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_ubjson/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
@@ -31408,6 +31473,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_ubjson(ptr, ptr + len, strict, allow_exceptions);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_ubjson/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
    static basic_json from_ubjson(detail::span_input_adapter&& i,
@@ -31536,6 +31602,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_bson/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
@@ -31546,6 +31613,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_bson(ptr, ptr + len, strict, allow_exceptions);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_bson/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
    static basic_json from_bson(detail::span_input_adapter&& i,
@@ -31578,6 +31646,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_unchecked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr)
@@ -31592,6 +31661,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_unchecked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    const_reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
@@ -31606,6 +31676,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_checked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/at/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr)
@@ -31620,6 +31691,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_checked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/at/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    const_reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
@@ -666,7 +666,7 @@ TEST_CASE("parse_float_fast declines what it cannot convert exactly")
    // always safe: the caller then falls back to a slower, exact conversion.
    const auto fast = [](const std::string & s, double & out)
    {
-        return nlohmann::detail::parse_float_fast(s.data(), s.data() + s.size(), out);
+        return nlohmann::detail::parse_float_fast(s.data(), s.data() + s.size(), '.', out);
    };
    double out = 0;

@@ -12,12 +12,7 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;

-#include <array>
 #include <clocale>
-#include <map>
-#include <string>
-#include <utility>
-#include <vector>

 struct ParserImpl final: public nlohmann::json_sax<json>
 {
@@ -180,208 +175,3 @@ TEST_CASE("locale-dependent test (LC_NUMERIC=de_DE)")
        MESSAGE("locale de_DE is not usable");
    }
 }
-
-namespace
-{
-// records the numbers of a flat array and switches LC_NUMERIC to the given
-// locale once the array opens - after the lexer was constructed, but before
-// any number in the array is lexed
-struct LocaleSwitchingSax final: public nlohmann::json_sax<json>
-{
-    explicit LocaleSwitchingSax(const char* switch_to)
-        : locale_after_open(switch_to)
-    {}
-
-    bool null() override
-    {
-        return true;
-    }
-    bool boolean(bool /*val*/) override
-    {
-        return true;
-    }
-    bool number_integer(json::number_integer_t /*val*/) override
-    {
-        return true;
-    }
-    bool number_unsigned(json::number_unsigned_t /*val*/) override
-    {
-        return true;
-    }
-    bool number_float(json::number_float_t val, const json::string_t& s) override
-    {
-        values.push_back(val);
-        strings.push_back(s);
-        return true;
-    }
-    bool string(json::string_t& /*val*/) override
-    {
-        return true;
-    }
-    bool binary(json::binary_t& /*val*/) override
-    {
-        return true;
-    }
-    bool start_object(std::size_t /*val*/) override
-    {
-        return true;
-    }
-    bool key(json::string_t& /*val*/) override
-    {
-        return true;
-    }
-    bool end_object() override
-    {
-        return true;
-    }
-    bool start_array(std::size_t /*val*/) override
-    {
-        switched = std::setlocale(LC_NUMERIC, locale_after_open.c_str()) != nullptr;
-        return true;
-    }
-    bool end_array() override
-    {
-        return true;
-    }
-    bool parse_error(std::size_t /*val*/, const std::string& /*val*/, const nlohmann::detail::exception& /*val*/) override
-    {
-        return false;
-    }
-
-    std::string locale_after_open;
-    bool switched = false;
-    std::vector<json::number_float_t> values {}; // NOLINT(readability-redundant-member-init)
-    std::vector<json::string_t> strings {}; // NOLINT(readability-redundant-member-init)
-};
-} // namespace
-
-TEST_CASE("locale changes between lexer construction and number conversion (#5198)")
-{
-    // The numbers are chosen so that the conversion also takes the strtod
-    // fallback, which honors the locale that is current at conversion time:
-    // too many significant digits for Clinger's fast path, an underflow that
-    // std::from_chars rejects, and a plain value.
-    const std::vector<std::string> numbers = {"3.14159265358979323846", "1.5e-400", "12.34", "-0.000123456789012345678"};
-    std::string text = "[";
-    for (const auto& n : numbers)
-    {
-        text += (text.size() == 1 ? "" : ",") + n;
-    }
-    text += "]";
-
-    using long_double_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, long double>;
-
-    // reference values, parsed without a locale switch
-    REQUIRE(std::setlocale(LC_NUMERIC, "C") != nullptr);
-    const json expected = json::parse(text);
-    const long_double_json expected_ld = long_double_json::parse(text);
-
-    const std::array<std::pair<const char*, const char*>, 2> transitions =
-    {
-        {
-            {"C", "de_DE"},
-            {"de_DE", "C"}
-        }
-    };
-
-    for (const auto& transition : transitions)
-    {
-        CAPTURE(transition.first);
-        CAPTURE(transition.second);
-
-        if (std::setlocale(LC_NUMERIC, transition.first) == nullptr)
-        {
-            MESSAGE("locale is not usable");
-            continue;
-        }
-
-        // SAX parsing
-        {
-            LocaleSwitchingSax sax(transition.second);
-            CHECK(json::sax_parse(text, &sax));
-            if (sax.switched)
-            {
-                CHECK(sax.values == expected.get<std::vector<json::number_float_t>>());
-                CHECK(sax.strings == numbers);
-            }
-        }
-
-        // DOM parsing with a callback
-        {
-            bool switched = false;
-            const auto cb = [&](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
-            {
-                if (event == json::parse_event_t::array_start)
-                {
-                    switched = std::setlocale(LC_NUMERIC, transition.second) != nullptr;
-                }
-                return true;
-            };
-            const json j = json::parse(text, cb);
-            if (switched)
-            {
-                CHECK(j == expected);
-            }
-        }
-
-        // a long double goes through std::strtold unless std::from_chars supports it
-        {
-            bool switched = false;
-            const auto cb = [&](int /*depth*/, long_double_json::parse_event_t event, long_double_json& /*parsed*/)
-            {
-                if (event == long_double_json::parse_event_t::array_start)
-                {
-                    switched = std::setlocale(LC_NUMERIC, transition.second) != nullptr;
-                }
-                return true;
-            };
-            const long_double_json j = long_double_json::parse(text, cb);
-            if (switched)
-            {
-                CHECK(j == expected_ld);
-            }
-        }
-    }
-
-    std::setlocale(LC_NUMERIC, "C");
-}
-
-TEST_CASE("locale with a multi-byte decimal point")
-{
-    // Some locales use a decimal point that is not a single character, e.g.
-    // U+066B ARABIC DECIMAL SEPARATOR (two bytes in UTF-8). It cannot be
-    // substituted in place for '.', so the strtod fallback stops early. The
-    // conversion must still terminate rather than retry forever.
-    const std::array<const char*, 6> names = {{"ar_EG.UTF-8", "ar_SA.UTF-8", "fa_IR.UTF-8", "ps_AF.UTF-8", "ar_EG", "fa_IR"}};
-    bool tested = false;
-    for (const char* name : names)
-    {
-        if (std::setlocale(LC_NUMERIC, name) == nullptr)
-        {
-            continue;
-        }
-        const std::string decimal_point = std::localeconv()->decimal_point;
-        if (decimal_point.size() < 2)
-        {
-            continue;
-        }
-        CAPTURE(name);
-        tested = true;
-
-        // too many significant digits for Clinger's fast path, and an underflow
-        // that std::from_chars rejects: both reach the strtod fallback
-        json j;
-        CHECK_NOTHROW(j = json::parse("[3.14159265358979323846, 1.5e-400, -0.000123456789012345678]"));
-        CHECK(j.is_array());
-        CHECK(json::accept("3.14159265358979323846"));
-
-        // a value the locale-independent paths convert is not affected
-        CHECK(json::parse("12.5") == 12.5);
-    }
-    if (!tested)
-    {
-        MESSAGE("no locale with a multi-byte decimal point is usable");
-    }
-
-    std::setlocale(LC_NUMERIC, "C");
-}
@@ -2208,11 +2208,8 @@ TEST_CASE("MessagePack Size above uint32 for array")
    auto& array = j.get_ref<huge_array_json::array_t&>();
    array.fake_size = true;

-    // write into a caller-owned vector: to_msgpack(j) reserves space based on
-    // the (faked) element count, which fails with bad_alloc on Windows
-    std::vector<std::uint8_t> result;
    CHECK_THROWS_WITH_AS(
-        huge_array_json::to_msgpack(j, result),
+        huge_array_json::to_msgpack(j),
        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
        json::out_of_range&);

@@ -2264,11 +2261,8 @@ TEST_CASE("MessagePack Size above uint32 for object")
    auto& object = j.get_ref<huge_object_json::object_t&>();
    object.fake_size = true;

-    // write into a caller-owned vector: to_msgpack(j) reserves space based on
-    // the (faked) element count, which fails with bad_alloc on Windows
-    std::vector<std::uint8_t> result;
    CHECK_THROWS_WITH_AS(
-        huge_object_json::to_msgpack(j, result),
+        huge_object_json::to_msgpack(j),
        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
        json::out_of_range&);

@@ -0,0 +1,127 @@
+# Public API Policy
+
+This document defines what counts as the **public API** of nlohmann/json for the purposes of the
+`tools/api_checker/` tooling, what stability is (and is not) guaranteed, and how API changes are
+classified as breaking or feature additions. It exists so that "public API" is a checkable, mechanical
+property of the source, not a matter of convention or memory — see
+[Discussion #3691](https://github.com/nlohmann/json/discussions/3691) for the original motivation.
+
+## What counts as public API
+
+The public API surface is derived from C++ semantics (class templates, access specifiers, namespace
+scoping) by `extract_api.py`, not from the presence of documentation. It consists of:
+
+1. **Public members of six class templates**: `basic_json`, `adl_serializer`,
+   `byte_container_with_subtype`, `json_pointer`, `json_sax`, `ordered_map`. Specifically, the *primary
+   template definition* (`CLASS_TEMPLATE` cursor with `is_definition() == True`) — never an implicit
+   instantiation, which silently drops SFINAE-guarded overloads. Two tiers apply:
+   - **Callable tier** (methods, constructors, destructors, conversion operators, function templates):
+     every public callable requires its own `@sa` documentation link, without exception.
+   - **Type tier** (public type aliases): requires `@sa`, except for a fixed exemption list of
+     STL-container named-requirement aliases that mirror standard-library conventions rather than being
+     independently documented: `value_type`, `reference`, `const_reference`, `pointer`, `const_pointer`,
+     `iterator`, `const_iterator`, `reverse_iterator`, `const_reverse_iterator`, `difference_type`,
+     `size_type`, `allocator_type`, `key_type`, `mapped_type`. This list is defined once, in
+     `extract_api.py`'s `stl_exempt` set, and referenced here rather than duplicated.
+2. **Free functions and operators in `nlohmann::`**, including `nlohmann::literals::json_literals`
+   (the `operator""_json` / `operator""_json_pointer` user-defined literals). Comparison and stream
+   operators on `basic_json` and `json_pointer`, `operator/`, `swap`.
+3. **The six alias-exposed exception types**: `basic_json::exception`, `parse_error`,
+   `invalid_iterator`, `type_error`, `out_of_range`, `other_error`. These are public `TYPE_ALIAS_DECL`s
+   in `basic_json` (e.g. `using exception = detail::exception;`) whose underlying class is physically
+   defined in `nlohmann::detail::exceptions.hpp`. `extract_api.py` follows the alias to find the `@sa` on
+   the underlying `detail::` class definition, since that's where the existing documentation convention
+   places it. Each exception class is documented as *one page* — its individual members (`what()`, `id`)
+   are not separately tracked, matching the existing one-page-per-class convention.
+4. **Macros**, governed separately by `docs/mkdocs/docs/api/macros/` (the curated list of ~30 pages is
+   authoritative) and cross-checked, advisory-only, by `check_macros.py`. See "Known limitations" below
+   for why macros can't be checked the same way as everything else.
+
+## What's excluded
+
+- **Everything in `nlohmann::detail::`**, with the one narrow exception above (exception-type aliases).
+  **No stability is guaranteed for any symbol in the `detail::` namespace — clients must not rely on it**,
+  regardless of whether a given `detail::` symbol happens to be reachable from user code today. This is
+  an explicit, deliberate policy, not an oversight.
+- **Private and protected members**, even of the six tracked classes. `extract_api.py` walks non-public
+  members only to check they don't carry a stray `@sa` (a documentation leak) — never to add them to the
+  public surface.
+- **The ABI inline-namespace segment** (`json_abi_v3_12_0`, `json_abi_diag_v3_12_0`, etc. — see
+  [docs/mkdocs/docs/features/namespace.md](../../docs/mkdocs/docs/features/namespace.md)). This is a
+  version-tag identity concern for `diff_api.py` (it must not make every release look like the entire API
+  was removed and re-added), not a scoping or visibility concern — the symbols inside it are public or
+  not independent of the tag.
+
+## Breaking vs. feature classification
+
+`diff_api.py` compares the `public_api` surface of two snapshots using an overload-disambiguating
+identity — `(scope, identity_name, kind, signature)`, where `signature` is the declaration's own
+source text (return type, name, parameter list, trailing qualifiers; comments and constructors'
+member-initializer-lists stripped). This is the third identity scheme this tooling has used; the
+first two were each found broken by testing against real release tags, not by inspection — see
+`extract_api.py`'s `identity_key()` docstring for the full history (a naive params-only key silently
+collided on overloads differing only by constness/SFINAE; libclang's USR fixed that but encoded the
+*enclosing class template's own arity*, so a single backward-compatible template-parameter addition
+made ~228 of 330 `basic_json` entries look "changed" between two real releases with zero actual
+breaking changes among them).
+
+- An identity present only in the **new** snapshot → **feature** (addition).
+- An identity present only in the **old** snapshot → **breaking** (removal).
+- The same `(scope, name)` with one identity removed and a different one added → reported as a
+  **changed overload**, classified breaking by default. No automatic overload-compatibility reasoning
+  is attempted — whether a signature change is source-compatible is a judgment call for a human
+  reviewer, not a sound problem for a CI tool to solve unsupervised.
+
+## Stable per-release API history
+
+`tools/api_checker/history/<tag>.json` holds one immutable, committed API-surface record per
+released `v3.*` tag (captured via `snapshot_release.py`; see `tools/api_checker/README.md` and
+`tools/api_checker/history/README.md`). `diff_api.py` reads from here automatically when a ref
+matches a stored file, instead of live-extracting via `git archive` every time.
+
+Every surface file (the live `api_surface.json` and every `history/*.json` record) carries a
+`format_version` integer. **Bump it whenever a change to the schema, or to the identity-computing
+algorithm (`get_signature_text()`/`get_identity_name()`/`identity_key()` in `extract_api.py`), could
+alter the `signature` or `identity_name` text for otherwise-unchanged source.** `diff_api.py` refuses
+by default to compare two surfaces with different `format_version` values — this is a direct,
+mechanical safeguard against the exact class of bug that motivated the current identity scheme (see
+above): a silent algorithm change corrupting every historical comparison with no way to detect it.
+An explicit `--allow-format-mismatch` flag exists for a deliberate, informed comparison anyway.
+
+Practical implication for anyone changing `extract_api.py`'s identity logic: bump
+`SURFACE_FORMAT_VERSION`, and treat every already-committed `history/*.json` file as needing a
+`--force` regeneration (reviewed, not blind) before it can be meaningfully compared against surfaces
+produced by the new algorithm version.
+
+## Stability guarantees
+
+This tooling makes the project's existing commitments *mechanically checkable* — it does not introduce a
+new promise:
+
+- `ChangeLog.md` states the project "adheres to [Semantic Versioning](http://semver.org/)."
+- [docs/mkdocs/docs/home/releases.md](../../docs/mkdocs/docs/home/releases.md) marks every 3.x release "All
+  changes are backward-compatible" (except 3.0.0 itself, a major bump with a migration guide).
+- `tests/abi/` provides a complementary, narrower guarantee: ABI/link compatibility *within one ABI tag*.
+  That is a binary-compatibility concern; this tooling's concern is source/API-level — a symbol can be
+  ABI-stable and still be a source-breaking change (e.g. a removed overload), or vice versa.
+
+## Known limitations
+
+- **Macros have no C++ access-specifier concept**, so the public/private test that works for classes
+  doesn't transfer. Only a minority of documented macro `#define`s have an attached `@sa`-style comment
+  (the `#ifndef X / #define X value #endif` idiom has no natural comment-attachment point), and internal
+  helper macros live in the same files as public configuration macros, so no path-based exclusion works
+  either. `check_macros.py` therefore only checks one direction: that every documented macro still has a
+  matching `#define` somewhere under `include/nlohmann/` (catches stale/renamed doc pages). It does
+  **not** attempt to detect undocumented macros — no reliable signal exists for that direction with the
+  current codebase conventions, and this tool doesn't pretend otherwise.
+- **`diff_api.py` does not track exception specifications or template-parameter-only changes.** A
+  function whose `noexcept` status changes, or whose template parameter list changes without altering
+  its externally-visible identity, will not be flagged.
+- **Known API-hygiene gap, surfaced by this tooling rather than fixed**:
+  `basic_json::insert_iterator` (a `public` member per C++ access rules) is a helper used internally by
+  `insert()`; its own source comment calls it "Helper for insertion of an iterator." It has no
+  documentation page and is deliberately left undocumented rather than either speculatively documented or
+  silently exempted — this is exactly the class of undocumented-and-probably-shouldn't-be-public symbol
+  this tooling exists to surface, per the motivating discussion. A future PR may reclassify it as private
+  as a (breaking, ABI-relevant) cleanup; that is out of scope here.
@@ -0,0 +1,393 @@
+# API Checker Tools
+
+Tooling to extract, validate, and track changes to the public API surface of nlohmann/json.
+
+## Overview
+
+These tools use libclang AST parsing to programmatically derive "the public API" from C++ semantics
+(class templates, access specifiers, namespace scoping) — independently of documentation status. The
+extracted surface is the source of truth for what is considered "public API." On top of this, the tools
+verify that every public entity carries a documentation link and detect API changes between releases.
+A per-release historical record lives in [`history/`](history/README.md), one file per tagged `v3.*`
+release, so past API changes can be derived without re-running libclang against old git refs.
+
+See [POLICY.md](POLICY.md) for the full definition of what counts as public API, what's excluded, how
+breaking vs. feature changes are classified, and known limitations.
+
+## Installation
+
+Install dependencies:
+
+```bash
+pip install -r tools/api_checker/requirements.txt
+```
+
+Requires:
+- Python 3.7+
+- libclang 18.1.1 (installed via pip)
+- clang++ or clang (system package, for include-path discovery only — does not need to
+  version-match the pinned libclang wheel)
+
+## Tools
+
+### extract_api.py
+
+Extract the public API surface by parsing C++ AST using libclang. Produces two different outputs for
+two different consumers — see "Two outputs, one extraction pass" below for why.
+
+**Usage:**
+```bash
+python3 tools/api_checker/extract_api.py \
+  --header include/nlohmann/json.hpp \
+  --include include \
+  --output api_snapshot.json \
+  --surface-output api_surface.json
+```
+
+**Options:**
+- `--header PATH` — Header file to analyze (default: `include/nlohmann/json.hpp`)
+- `--include PATH` — Include directory for parsing (default: `include`)
+- `--output PATH` — Full snapshot output (location + doc status; default: `api_snapshot.json`)
+- `--surface-output PATH` — Minimal surface output (identity only; omit to skip)
+- `--extra-isystem PATH` — Extra `-isystem` include path (repeatable), in case system-include
+  discovery via `clang++ -E -v` ever fails on a given runner image
+- `--self-test` — Run self-tests and exit (validates ABI-tag stripping)
+
+**How it works:**
+Parses the header file using libclang with `PARSE_DETAILED_PROCESSING_RECORD`, discovers system
+includes via `clang++ -E -x c++ -v /dev/null`, and walks the AST:
+
+1. For each of the 6 public class templates (`basic_json`, `adl_serializer`, `byte_container_with_subtype`,
+   `json_pointer`, `json_sax`, `ordered_map`): locate the `CLASS_TEMPLATE` cursor with `is_definition() == True`
+   — never a `CLASS_DECL` implicit instantiation, which silently drops SFINAE-guarded overloads
+2. Extract public members: `CXX_METHOD`, `CONSTRUCTOR`, `DESTRUCTOR`, `CONVERSION_FUNCTION`, `FUNCTION_TEMPLATE`
+   (callable tier — strict `@sa` requirement), and `TYPE_ALIAS_DECL` (type tier — with STL-container exemptions)
+3. Extract free functions in `nlohmann::` namespace (excluding `detail::` and `std::`)
+4. Normalize away ABI inline-namespace (regex `::json_abi[a-z_]*_v\d+_\d+_\d+` → `::`)
+5. Use overload-disambiguating identity keys built from raw source-text signature capture,
+   ABI-tag-stripped — see "Identity keys" below
+
+**Two outputs, one extraction pass:**
+- `--output` (full snapshot): each entry carries `location` (file:line) and documentation status
+  (`doc_url`, `has_sa`). Consumed by `check_docs.py`. **Not meant to be committed** — `location` shifts
+  on any unrelated code edit and `doc_url` changes when doc pages move, so a diff of this file mixes real
+  API changes with pure noise.
+- `--surface-output` (minimal surface): each entry has only `scope`, `kind`, `name`, `identity_name`,
+  `tier`, `signature`, and `pretty_signature` — nothing that can change without the API itself changing.
+  **This is the file that gets committed** (`tools/api_checker/api_surface.json` for the current
+  working tree, `tools/api_checker/history/<tag>.json` per released tag) and diffed by `diff_api.py`.
+
+**Identity keys — three approaches were tried and rejected before arriving at the current one:**
+1. `{scope, name, kind, params}` from `cursor.get_arguments()`: silently collided for any overload set
+   differentiated only by constness, ref-qualifiers, or SFINAE constraints rather than parameter types —
+   confirmed empirically: `basic_json`'s two zero-argument `get()` overloads (one `const`, one not) both
+   produced `params=[]` and silently overwrote each other. A full scan found **59 such silent overwrites
+   across 27 colliding names**.
+2. libclang's USR: correctly disambiguates every overload (it encodes the full mangled signature) — but
+   *also* encodes the enclosing class template's own arity into every member's USR. Confirmed
+   empirically against real release tags: `basic_json` gaining one new defaulted template parameter
+   between v3.11.2 and v3.11.3 (a backward-compatible change) changed literally every member's USR,
+   which made `diff_api.py` report **228 of 330 entries as "changed"** for a release with zero real
+   breaking changes among them.
+3. **Current approach**: raw source-text signature capture — `identity = (scope, identity_name, kind,
+   signature)`, where `signature` is the declaration's own text (return type, name, parameter list,
+   trailing cv/ref/noexcept qualifiers; comments and constructors' member-initializer-lists stripped;
+   stops before the function body) read directly via the cursor's byte-offset extent. This is what's
+   actually written in source — declared names like `ValueType`, never a resolved
+   `basic_json<T0,...,T10>` — so it's immune to the class-arity problem above. Verified by manually
+   cross-referencing every "added"/"removed"/"changed" entry in three real release-to-release diffs
+   (v3.11.2→v3.11.3, v3.11.3→v3.12.0, v3.12.0→HEAD) against the actual `git diff` of the source — every
+   one confirmed genuine. Full details, including several further edge-case fixes found the same way
+   (a libclang tokenizer gap, comment-stripping, constructor-name arity-poisoning), are in
+   `extract_api.py`'s `identity_key()`/`get_signature_text()` docstrings.
+
+**Output (full snapshot, from `--output`):**
+```json
+{
+  "meta": {
+    "extracted_from": "include/nlohmann/json.hpp"
+  },
+  "public_api": {
+    "<opaque internal key, not meant to be read>": {
+      "scope": "nlohmann::basic_json",
+      "name": "parse",
+      "identity_name": "parse",
+      "kind": "CXX_METHOD",
+      "tier": "callable",
+      "signature": "static basic_json parse ( InputType && i , ... )",
+      "location": "include/nlohmann/json.hpp:4104",
+      "doc_url": "https://json.nlohmann.me/api/basic_json/parse/",
+      "has_sa": true,
+      "pretty_signature": "nlohmann::basic_json::parse"
+    }
+  },
+  "documented_non_public": []
+}
+```
+
+`documented_non_public` lists entities **not** part of the public surface (private/protected members of
+the six tracked classes) that surprisingly carry an `@sa` URL into the documentation site
+(`https://json.nlohmann.me/`) — a genuine documentation leak. `@sa` links to anything else, such as GitHub
+issues, are ignored. It does not list public entries that merely lack `@sa`; that's `check_docs.py`'s job.
+
+**Output (surface, from `--surface-output`):**
+```json
+{
+  "format_version": 1,
+  "meta": {
+    "extracted_from": "include/nlohmann/json.hpp"
+  },
+  "public_api": [
+    {
+      "scope": "nlohmann::basic_json",
+      "kind": "CXX_METHOD",
+      "name": "parse",
+      "identity_name": "parse",
+      "tier": "callable",
+      "signature": "static basic_json parse ( InputType && i , parser_callback_t cb = nullptr , const bool allow_exceptions = true , const bool ignore_comments = false )",
+      "pretty_signature": "nlohmann::basic_json::parse"
+    }
+  ]
+}
+```
+
+A flat, sorted list of self-describing records — `signature`/`identity_name` are the same values
+`identity_key()` joins into one opaque internal string, exposed here as explicit fields so the file is
+readable and diffable by inspection, not just by tooling. `identity_name` differs from `name` only for
+constructors/destructors (a canonical `"(constructor)"`/`"(destructor)"` placeholder — see
+`get_identity_name()`'s docstring for why `cursor.spelling` isn't used directly there).
+
+`format_version` guards against a future change to this schema or to the identity-computing algorithm
+silently corrupting a comparison against an older stored surface — bump it whenever such a change could
+alter `signature`/`identity_name` text for otherwise-unchanged source (see `diff_api.py`).
+
+### check_docs.py
+
+Verify that all public API entries have valid documentation links and that no non-public entities
+carry `@sa` comments.
+
+**Usage:**
+```bash
+python3 tools/api_checker/check_docs.py --snapshot api_snapshot.json
+```
+
+**Options:**
+- `--snapshot PATH` — Full API snapshot JSON file from `extract_api.py --output` (default: `api_snapshot.json`)
+
+**How it works:**
+Two-pass validation over the extracted snapshot:
+
+1. For every `public_api` entry (callable tier, and type tier minus STL exemptions): flag if missing `@sa`,
+   flag if `@sa` URL doesn't resolve to an existing documentation file (following `docs/mkdocs/mkdocs.yml`'s
+   `redirect_maps` when a page has moved, and trying the class-overview conventions used by different
+   classes — flat `<class>.md`, nested `<class>/<class>.md`, nested `<class>/index.md`)
+2. For every `documented_non_public` entry: flag as unexpected `@sa` on a non-public entity
+
+**Output:**
+Prints warnings for each issue, categorized by rule:
+- `docs/missing_sa_comment` — public API without `@sa` documentation link
+- `docs/missing_doc_file` — `@sa` URL points to non-existent `.md` file
+- `docs/invalid_sa_url` — malformed `@sa` URL
+- `docs/sa_on_non_public` — unexpected `@sa` on a non-public entity
+
+Exits with status 0 if all checks pass, 1 if issues found.
+
+### diff_api.py
+
+Compare the public API surface between two refs and classify changes as feature (added) or
+breaking (removed / changed overload).
+
+**Usage:**
+```bash
+python3 tools/api_checker/diff_api.py --old v3.12.0 --new HEAD
+python3 tools/api_checker/diff_api.py --old v3.11.2 --new v3.11.3          # both resolved from history/
+python3 tools/api_checker/diff_api.py --old v3.12.0 --new HEAD --fail-on-breaking
+python3 tools/api_checker/diff_api.py --old-file a.json --new-file b.json  # compare two files directly
+```
+
+**Options:**
+- `--old REF` / `--new REF` — Refs to compare (tags, branches, commits). `--new` defaults to `HEAD`.
+  Each is resolved by checking `tools/api_checker/history/<ref>.json` first (fast — no libclang or
+  git-archive needed), falling back to live extraction if no matching file exists there.
+- `--old-file PATH` / `--new-file PATH` — Load an arbitrary surface JSON file directly, bypassing
+  both git and `tools/api_checker/history/`. Mutually exclusive with `--old`/`--new` respectively.
+- `--no-history` — Force live extraction even when a matching `tools/api_checker/history/<ref>.json`
+  exists. Useful to check that a stored record is still faithful to a fresh run of the current tool.
+- `--allow-format-mismatch` — Proceed even if the two surfaces have different `format_version`
+  (otherwise `diff_api.py` refuses — see below).
+- `--header PATH` / `--include PATH` — For live extraction only (default:
+  `include/nlohmann/json.hpp` / `include`)
+- `--fail-on-breaking` — Exit with status 1 if breaking changes are detected
+
+**How it works:**
+For a ref not found in `tools/api_checker/history/`, checks out the **full `include/` tree** at
+that ref into a temp directory via `git archive` (a single-file checkout of `json.hpp` is not
+enough — it `#include`s dozens of other headers that must exist at the same ref), then runs the
+*current* `extract_api.py --surface-output` against it. Diffs the two surfaces by identity
+(`scope`, `identity_name`, `kind`, `signature`):
+- Identity only in the new surface → **feature**.
+- Identity only in the old surface → **breaking** (removed).
+- Same `(scope, name)` with a removed identity and an added identity → grouped as a **changed
+  overload**, breaking by default. No automatic overload-compatibility reasoning is attempted — a
+  human judges whether the change is actually source-compatible.
+
+Before diffing, the two surfaces' `format_version` fields are compared; a mismatch aborts with an
+error (override with `--allow-format-mismatch`) rather than silently producing an unsound diff — see
+`extract_api.py`'s `SURFACE_FORMAT_VERSION` docstring for the incident that motivated this guard.
+
+ABI-tag stripping is inherited automatically since both extractions go through the same
+`extract_api.py`.
+
+**Use case:** Run before cutting a release to verify the changelog correctly categorizes changes as
+breaking vs. features.
+
+### snapshot_release.py
+
+Capture an immutable, per-release API surface record into `tools/api_checker/history/<tag>.json`.
+This is what makes `diff_api.py` fast for released tags — see "How it works" above.
+
+**Usage:**
+```bash
+python3 tools/api_checker/snapshot_release.py --ref v3.12.0
+python3 tools/api_checker/snapshot_release.py --ref v3.11.0 --ref v3.12.0   # repeatable
+python3 tools/api_checker/snapshot_release.py --all-tags                    # every v3.* tag
+python3 tools/api_checker/snapshot_release.py --ref v3.12.0 --force         # overwrite an existing record
+```
+
+**Options:**
+- `--ref REF` — Git tag to snapshot; repeatable
+- `--all-tags` — Snapshot every `v3.*` tag (existing files are skipped unless `--force`)
+- `--output-dir PATH` — Where to write (default: `tools/api_checker/history/`)
+- `--force` — Overwrite an existing history file. History files are immutable by convention —
+  only pass this for a deliberate, reviewed regeneration; review the resulting diff before
+  committing
+- `--header PATH` / `--include PATH` — Same as `diff_api.py`'s live-extraction options
+
+**How it works:** Reuses `diff_api.py`'s `extract_surface_for_ref()` for the git-archive-and-extract
+work, then adds `generated_at`/`generator` provenance and writes the result to
+`tools/api_checker/history/<ref>.json`. Given multiple refs (or `--all-tags`), does **not** abort
+the batch on one failing ref — collects failures and prints a summary at the end, so one
+unparseable old tag doesn't block backfilling the releases that do work. See
+`tools/api_checker/history/README.md` for the currently-known gaps (pre-restructuring tags that
+predate the `include/nlohmann/` layout entirely).
+
+**Not CI-automated** — this is a manual step in the release checklist (see below), by design.
+
+### check_macros.py
+
+Advisory-only cross-check between documented macros and their `#define`/reference sites. **Never blocks
+CI**, regardless of findings.
+
+**Usage:**
+```bash
+python3 tools/api_checker/check_macros.py
+```
+
+**Options:**
+- `--macros-dir PATH` — Directory of macro doc pages (default: `docs/mkdocs/docs/api/macros`)
+- `--include-dir PATH` — Directory to search for `#define`/reference sites (default: `include/nlohmann`)
+
+**How it works:**
+For each `.md` page under `docs/mkdocs/docs/api/macros/` (excluding `index.md`), extracts the macro
+name(s) from the H1 heading — handling both plain single-macro headings and multi-line HTML headings
+that list a family of related macros (e.g. the `NLOHMANN_DEFINE_DERIVED_TYPE_*` family) — then checks
+whether each name is defined **or referenced** (`#define`, `#ifdef`, `#ifndef`, `defined(...)`) anywhere
+under `include/nlohmann/`. Referenced-but-not-defined is deliberately accepted: macros like
+`JSON_NOEXCEPTION` or `JSON_THROW_USER` are user-supplied overrides that the library only checks for,
+never defines itself.
+
+Only checks the documented-macro-still-exists direction (catches stale/renamed doc pages). Does **not**
+check the converse (undocumented macros) — see [POLICY.md](POLICY.md)'s "Known limitations" for why.
+
+## Continuous Integration
+
+A GitHub Actions workflow (`.github/workflows/check_api_docs.yml`) runs on every pull request:
+
+1. Installs `clang` (system package, for include discovery) and Python dependencies
+2. Runs `extract_api.py`, regenerating both the ephemeral full snapshot and the tracked
+   `tools/api_checker/api_surface.json`
+3. Runs `check_docs.py` — **Phase 1: advisory** (`continue-on-error: true`), surfacing the doc backlog
+   without failing the job while it's burned down. Will flip to blocking once the backlog is cleared.
+4. Runs `check_macros.py` — always advisory
+5. Diffs `tools/api_checker/api_surface.json` against the regenerated copy — **blocking from the start**
+   (unlike the doc-backlog check, this is purely mechanical regeneration with no backlog to phase in,
+   matching the precedent set by `check_amalgamation.yml`). Uploads a patch artifact if it differs, so
+   contributors can `git apply` it instead of installing libclang locally.
+
+## Workflow: Adding New Public API
+
+1. Add the new public method/function to the header
+2. Add a `/// @sa https://json.nlohmann.me/api/<class>/<member>/` comment above it
+3. Create the corresponding documentation page at `docs/mkdocs/docs/api/<class>/<member>.md` and a
+   `mkdocs.yml` nav entry
+4. Regenerate and commit the tracked surface file:
+   ```bash
+   python3 tools/api_checker/extract_api.py --surface-output tools/api_checker/api_surface.json
+   git add tools/api_checker/api_surface.json
+   ```
+5. Push your PR — CI verifies both the doc link and that the surface file is up to date
+
+## Workflow: Release Checklist
+
+Before cutting a release:
+
+```bash
+# Diff current API against the previous release
+python3 tools/api_checker/diff_api.py --old v3.12.0 --new HEAD
+
+# Review the output to verify the changelog correctly categorizes breaking vs. feature changes
+```
+
+After tagging the release:
+
+```bash
+# Capture and commit the new tag's API surface, so future diffs against it hit the fast,
+# stored-file path instead of live-extracting every time. A manual step, not CI-automated.
+python3 tools/api_checker/snapshot_release.py --ref v3.13.0
+git add tools/api_checker/history/v3.13.0.json
+```
+
+## Troubleshooting
+
+**libclang not found:**
+```
+Error: Could not locate libclang library
+```
+→ Ensure libclang is installed: `python3 -m pip install libclang==18.1.1`
+
+**Parse errors in header:**
+```
+Parse errors encountered:
+  ... list of diagnostics ...
+```
+→ Check that system includes can be discovered. Run `clang++ -E -x c++ -v /dev/null` and verify
+the output includes a section titled `#include <...> search starts here:` with system paths.
+If include discovery fails, use `--extra-isystem PATH` to provide additional paths.
+
+**No API entries extracted (or very few):**
+- Check that the header file exists and is valid C++: `ls -la include/nlohmann/json.hpp`
+- Verify that no parse errors occur above
+- Confirm that you're targeting a `CLASS_TEMPLATE` definition, not an implicit instantiation
+  (the tool logs `Found N public API entries` — a zero or very small count suggests the wrong cursor kind)
+
+**Doc link returns 404:**
+- Verify the file exists at the expected path: `docs/mkdocs/docs/api/<class>/<member>.md`
+- Check for URL encoding issues (e.g., `operator[]` → `operator%5B%5D`)
+- Verify the URL structure in the `@sa` comment: should be `https://json.nlohmann.me/api/<path>/`
+- Check `docs/mkdocs/mkdocs.yml`'s `redirect_maps` if the page has moved
+
+**`tools/api_checker/api_surface.json` is out of date in CI:**
+→ Regenerate and commit it: `python3 tools/api_checker/extract_api.py --surface-output tools/api_checker/api_surface.json`
+
+**`diff_api.py` refuses with "format_version mismatch":**
+→ One side is a stored surface (live `api_surface.json` or a `tools/api_checker/history/*.json`
+file) captured with an older/newer version of `extract_api.py`'s identity-computing algorithm than
+the other side. Comparing them directly could produce an unsound diff (this is exactly the failure
+mode that motivated adding the check — see `extract_api.py`'s `SURFACE_FORMAT_VERSION` docstring).
+Either regenerate the older side with the current tool, or pass `--allow-format-mismatch` if you
+understand the risk and want to proceed anyway.
+
+## Contributing
+
+Report bugs or suggest improvements to [Discussion #3691](https://github.com/nlohmann/json/discussions/3691).
+Read [POLICY.md](POLICY.md) first for the definition of public API this tooling enforces.
@@ -0,0 +1,185 @@
+#!/usr/bin/env python3
+"""
+Verify that public API entries have documentation links.
+
+Consumes an API snapshot from extract_api.py and checks:
+1. Every public callable/type-tier entry has an @sa comment (with exceptions)
+2. Every @sa URL resolves to an existing documentation file
+3. No @sa comments appear on non-public entities
+"""
+
+import argparse
+import json
+import os
+import re
+# subprocess is only called with fixed argument lists, never through a shell.
+import subprocess  # nosec B404
+import sys
+from urllib.parse import unquote
+
+warnings = 0
+
+# STL-container-named-requirement aliases that are exempt from @sa requirement
+STL_EXEMPT = {'value_type', 'reference', 'const_reference', 'pointer', 'const_pointer',
+              'iterator', 'const_iterator', 'reverse_iterator', 'const_reverse_iterator',
+              'difference_type', 'size_type', 'allocator_type', 'key_type', 'mapped_type'}
+
+
+def get_repo_root():
+    """Find the repository root via git, so this script works regardless of invoking CWD."""
+    try:
+        result = subprocess.run(  # nosec B603 B607
+            ['git', 'rev-parse', '--show-toplevel'],
+            capture_output=True, text=True, check=True, timeout=10
+        )
+        return result.stdout.strip()
+    except (subprocess.CalledProcessError, FileNotFoundError, subprocess.TimeoutExpired):
+        return os.getcwd()
+
+
+REPO_ROOT = get_repo_root()
+MKDOCS_YML = os.path.join(REPO_ROOT, 'docs', 'mkdocs', 'mkdocs.yml')
+
+
+def load_redirect_map() -> dict:
+    """
+    Parse the redirect_maps block of docs/mkdocs/mkdocs.yml: {old_relative_path: new_relative_path}.
+
+    mkdocs' redirect plugin lets a doc page move without breaking existing @sa URLs -- e.g.
+    'api/basic_json/operator_ltlt.md' redirects to the real file at 'api/operator_ltlt.md'.
+    Without consulting this map, url_to_docfile() would flag every redirected URL as a broken link.
+    """
+    if not os.path.exists(MKDOCS_YML):
+        return {}
+    with open(MKDOCS_YML) as f:
+        content = f.read()
+    redirect_map = {}
+    for m in re.finditer(r"^\s*'([^']+\.md)':\s*(\S+\.md)\s*$", content, re.MULTILINE):
+        redirect_map[m.group(1)] = m.group(2)
+    return redirect_map
+
+
+REDIRECT_MAP = load_redirect_map()
+
+
+def report(rule: str, location: str, description: str):
+    """Report a documentation issue."""
+    global warnings
+    warnings += 1
+    print(f'{warnings:3}. {location}:  {description} [{rule}]')
+
+
+def url_to_docfile(url: str) -> str | None:
+    """Convert @sa URL to the documentation file it resolves to, following mkdocs redirects."""
+    if not url:
+        return None
+
+    # Extract path after /api/
+    match = re.search(r'/api/(.+?)/?$', url)
+    if not match:
+        return None
+
+    # URL-decode each path component
+    path_parts = [unquote(part) for part in match.group(1).split('/')]
+    relative_path = 'api/' + '/'.join(path_parts) + '.md'
+
+    docs_root = os.path.join(REPO_ROOT, 'docs', 'mkdocs', 'docs')
+    direct_path = os.path.join(docs_root, relative_path)
+
+    # Class-overview URLs (a single path segment after /api/, e.g. ".../api/json_pointer/")
+    # use inconsistent on-disk conventions across classes: ordered_map.md is a flat file,
+    # byte_container_with_subtype/byte_container_with_subtype.md nests under a same-named
+    # file, json_pointer/index.md nests under index.md. Try all observed conventions.
+    candidates = [direct_path]
+    if len(path_parts) == 1:
+        stem = path_parts[0]
+        candidates.append(os.path.join(docs_root, 'api', stem, 'index.md'))
+        candidates.append(os.path.join(docs_root, 'api', stem, stem + '.md'))
+
+    redirected = REDIRECT_MAP.get(relative_path)
+    if redirected:
+        candidates.append(os.path.join(docs_root, redirected))
+
+    for candidate in candidates:
+        if os.path.exists(candidate):
+            return candidate
+
+    # Nothing resolved -- return the direct path so the caller reports a meaningful "missing" location.
+    return direct_path
+
+
+def check_docs(snapshot_path: str):
+    """Check documentation for all API entries."""
+    if not os.path.exists(snapshot_path):
+        print(f"Error: Snapshot file not found: {snapshot_path}")
+        sys.exit(1)
+
+    with open(snapshot_path, 'r') as f:
+        data = json.load(f)
+
+    api = data.get('public_api', {})
+    documented_non_public = data.get('documented_non_public', [])
+
+    print(f"Checking documentation for {len(api)} API entries...")
+    print(120 * "-")
+
+    # Check public API entries
+    for _identity_key, entry in sorted(api.items()):
+        location = entry.get('location', 'unknown')
+        name = entry.get('name', '?')
+        tier = entry.get('tier', '?')
+        doc_url = entry.get('doc_url')
+        has_sa = entry.get('has_sa', False)
+
+        # Skip type_exempt tier entries
+        if tier == 'type_exempt':
+            continue
+
+        # Check for missing @sa
+        if not has_sa:
+            report('docs/missing_sa_comment', location,
+                  f'public API "{name}" (tier: {tier}) has no @sa documentation link')
+            continue
+
+        # Verify URL resolves to an existing file
+        doc_file = url_to_docfile(doc_url)
+        if not doc_file:
+            report('docs/invalid_sa_url', location,
+                  f'public API "{name}" has invalid @sa URL: {doc_url}')
+            continue
+
+        if not os.path.exists(doc_file):
+            display_path = os.path.relpath(doc_file, REPO_ROOT)
+            report('docs/missing_doc_file', location,
+                  f'public API "{name}" @sa URL points to non-existent file: {display_path}')
+
+    # Check documented_non_public entries
+    for entry in documented_non_public:
+        location = entry.get('location', 'unknown')
+        reason = entry.get('reason', '?')
+        report('docs/sa_on_non_public', location,
+              f'@sa comment found on non-public entity: {reason}')
+
+    print(120 * "-")
+
+    if warnings > 0:
+        print(f"\nFound {warnings} documentation issues")
+        return False
+    else:
+        print("\nAll public API entries are properly documented ✓")
+        return True
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Check documentation for public API')
+    parser.add_argument('--snapshot', default='api_snapshot.json',
+                       help='Path to API snapshot JSON file')
+
+    args = parser.parse_args()
+
+    if not check_docs(args.snapshot):
+        sys.exit(1)
+
+
+if __name__ == '__main__':
+    main()
@@ -0,0 +1,135 @@
+#!/usr/bin/env python3
+"""
+Advisory-only cross-check between documented macros and their #define sites.
+
+Macros have no C++ access-specifier concept, so the AST-based public/private test that
+extract_api.py uses for classes doesn't transfer -- see tools/api_checker/POLICY.md's "Known
+limitations" section. This script only checks one direction: that every macro documented under
+docs/mkdocs/docs/api/macros/ still has a matching #define somewhere under include/nlohmann/,
+catching stale or renamed doc pages. It does NOT check the converse (undocumented macros) --
+no reliable signal exists for that direction given this codebase's conventions.
+
+Never blocks CI -- always exits 0, even when it reports findings.
+"""
+
+import argparse
+import glob
+import os
+import re
+import sys
+
+MACRO_TOKEN_RE = re.compile(r'\b([A-Z][A-Z0-9_]*)\b')
+
+warnings = 0
+
+
+def report(location: str, description: str):
+    global warnings
+    warnings += 1
+    print(f'{warnings:3}. {location}:  {description}')
+
+
+def extract_macro_names(md_path: str) -> list:
+    """
+    Extract macro name(s) from a doc page's H1 heading.
+
+    Most pages use a single-line markdown heading ('# JSON_ASSERT'). A few document a family of
+    related macros under one page using a multi-line HTML heading listing comma-separated names
+    (e.g. NLOHMANN_DEFINE_DERIVED_TYPE_INTRUSIVE, ..._WITH_DEFAULT, ..._ONLY_SERIALIZE). Handle
+    both: collect the heading text (markdown '# ...' line, or everything between <h1> and </h1>,
+    which may span multiple lines), then split on commas.
+    """
+    with open(md_path) as f:
+        content = f.read()
+
+    heading_text = None
+    html_match = re.search(r'<h1>(.*?)</h1>', content, re.DOTALL)
+    if html_match:
+        heading_text = html_match.group(1)
+    else:
+        for line in content.splitlines():
+            if line.startswith('# '):
+                heading_text = line[2:]
+                break
+
+    if not heading_text:
+        return []
+
+    names = []
+    for part in heading_text.split(','):
+        match = MACRO_TOKEN_RE.search(part)
+        if match:
+            names.append(match.group(1))
+    return names
+
+
+def macro_is_referenced(macro_name: str, include_dir: str) -> bool:
+    """
+    Check whether macro_name is defined or referenced anywhere under include_dir.
+
+    A reference is any #ifdef, #ifndef, or defined() check.
+
+    Some documented macros (e.g. JSON_NOEXCEPTION, JSON_THROW_USER) are user-supplied overrides:
+    the library only checks whether they're defined, it never #defines them itself. Requiring a
+    literal #define would make this advisory check permanently noisy for that whole category, so
+    presence of any reference is treated as "this macro still exists in the codebase."
+    """
+    pattern = re.compile(
+        r'#\s*define\s+' + re.escape(macro_name) + r'\b'
+        r'|#\s*ifn?def\s+' + re.escape(macro_name) + r'\b'
+        r'|defined\s*\(\s*' + re.escape(macro_name) + r'\s*\)'
+        r'|defined\s+' + re.escape(macro_name) + r'\b'
+    )
+    for root, _dirs, files in os.walk(include_dir):
+        for fname in files:
+            if not fname.endswith('.hpp'):
+                continue
+            path = os.path.join(root, fname)
+            with open(path, encoding='utf-8', errors='ignore') as f:
+                if pattern.search(f.read()):
+                    return True
+    return False
+
+
+def check_macros(macros_dir: str, include_dir: str) -> bool:
+    md_files = sorted(glob.glob(os.path.join(macros_dir, '*.md')))
+    md_files = [f for f in md_files if os.path.basename(f) != 'index.md']
+
+    print(f"Checking {len(md_files)} documented macros against #define sites in {include_dir}...")
+    print(120 * "-")
+
+    for md_path in md_files:
+        macro_names = extract_macro_names(md_path)
+        if not macro_names:
+            report(md_path, "could not extract macro name(s) from H1 heading")
+            continue
+
+        for macro_name in macro_names:
+            if not macro_is_referenced(macro_name, include_dir):
+                report(md_path, f'documented macro "{macro_name}" is not defined or referenced under {include_dir}')
+
+    print(120 * "-")
+
+    if warnings > 0:
+        print(f"\nFound {warnings} stale/renamed macro doc pages (advisory only, not blocking)")
+    else:
+        print("\nAll documented macros have a matching #define ✓")
+
+    return warnings == 0
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Advisory cross-check of documented macros vs. #define sites')
+    parser.add_argument('--macros-dir', default='docs/mkdocs/docs/api/macros',
+                       help='Directory containing macro documentation pages')
+    parser.add_argument('--include-dir', default='include/nlohmann',
+                       help='Directory to search for #define sites')
+
+    args = parser.parse_args()
+    check_macros(args.macros_dir, args.include_dir)
+    # Advisory only -- never fail CI regardless of findings.
+    sys.exit(0)
+
+
+if __name__ == '__main__':
+    main()
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Niels Lohmann	da5097abcd	Restore the CI spelling of json_pointer's operator string_t in the API surface The develop merge regenerated api_surface.json on macOS, whose libclang spells the name of the deprecated conversion operator as "operator nlohmann::json_pointer::string_t_helper<...>::type". CI's pinned libclang 18.1.1 on Linux spells it "operator typename string_t_helper<...>::type", so check_api_docs reported the file as out of date. This restores CI's spelling, which is byte-identical to the file CI regenerated. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-27 21:37:14 +02:00
Niels Lohmann	2319f6e6f9	Address Codacy findings in the API checker scripts Put multi-line docstring summaries on their own line, as a single sentence followed by a blank line (pydocstyle D205, D209, D213, D415). Annotate the subprocess import and calls with nosec: they only run fixed argument lists, never through a shell (Bandit B404, B603, B607). Do the same for the three broad except clauses in extract_api.py, which deliberately fall through to the next libclang candidate or skip an unresolvable alias (Bandit B110, B112). Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-27 18:09:03 +02:00
Niels Lohmann	9a0d1c0c47	Merge branch 'develop' into claude/todo-191-plan-508110 Resolve the conflict in docs/mkdocs/docs/home/architecture.md by taking develop's rewritten page and pointing its ordered_map links at the moved api/ordered_map/index.md. Also update the ordered_map.md links develop added in ordered_json.md, object_order.md, and template_parameters.md. Regenerate api_surface.json for the new BON8 functions and the changed comparison operator. Restrict the documented_non_public leak check to @sa URLs into json.nlohmann.me: develop now uses @sa to link GitHub issues from private members such as copy_structured, which is not a documentation leak. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-27 18:07:00 +02:00
Niels Lohmann	1bbb5d400a	Regenerate api_surface.json after merging develop develop added JSON_HEDLEY_WARN_UNUSED_RESULT to a number of basic_json members (#5520) and reworked operator<<'s output adapter, so the committed API surface no longer matched what extract_api.py produces and the "Check for uncommitted API surface changes" step failed. This is the patch the workflow itself uploads for that purpose; the changes are limited to recorded signatures plus the way libclang spells json_pointer's conversion operator. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-15 10:06:55 +02:00
Niels Lohmann	08d18d5a82	Merge remote-tracking branch 'origin/develop' into HEAD	2026-09-14 21:26:29 +02:00
Niels LohmannandClaude Sonnet 5	a27065bd12	Regenerate api_surface.json after merging develop develop gained iterator+sentinel support for accept()/parse()/sax_parse()/ from_cbor()/from_msgpack()/from_ubjson()/from_bjdata()/from_bson() (#5205) since this branch was created, which check_api_docs.yml's drift check caught immediately: GitHub's pull_request trigger checks out the PR-vs-base merge commit, not the PR branch in isolation, so CI was comparing the committed api_surface.json (generated before that upstream change existed) against a fresh extraction of a json.hpp that already had it. This superseded an earlier, incorrect diagnosis of the same symptom (a JSON_HAS_RANGES cross-environment pin) -- that fix remains in place since it's still a real, independent determinism improvement for three other JSON_HAS_RANGES-gated locations in type_traits.hpp, but it wasn't the actual cause of this particular mismatch: these new overloads turned out to be unconditional (SFINAE-gated via can_compare_ne, not preprocessor-gated), so no environment-detection difference was involved here at all. Signed-off-by: Niels Lohmann <mail@nlohmann.me> Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-07-11 23:45:46 +02:00
Niels Lohmann	3940f4b730	Merge remote-tracking branch 'origin/develop' into claude/todo-191-plan-508110	2026-07-11 23:43:30 +02:00
Niels LohmannandClaude Sonnet 5	0663907b68	Fix cross-environment API-surface drift and lint findings from CI extract_api.py's own extraction wasn't deterministic across machines, which CI's drift check caught immediately: JSON_HAS_RANGES auto-detects via the standard library's __cpp_lib_ranges feature-test macro, which isn't reliably gated to C++20 mode by every stdlib -- undefined under -std=c++17 with macOS's libc++, but defined under the identical flag with the Ubuntu stdlib CI uses, so parse()/accept()/from_*() extracted different signatures purely depending on which machine ran the extraction. Pinned to -DJSON_HAS_RANGES=0: the deterministic and safe choice, since pinning to 1 was tried first and found to fail to parse on a stdlib without full <ranges> support even when the macro claims otherwise. Also found and fixed a second, independent source of the same class of drift: get_identity_name() used cursor.spelling verbatim for CONVERSION_FUNCTION cursors, which libclang renders as its own internally-canonicalized form of the return type rather than what's literally written. Confirmed for json_pointer::operator string_t() spelling differently on two machines pinned to the identical libclang==18.1.1 wheel, with the JSON_HAS_RANGES fix above ruled out as the cause. Now derived from the cursor's own raw source text instead, immune to libclang's dependent-type resolution differences and incidentally more readable than the libclang-internal forms it replaces. Bumped SURFACE_FORMAT_VERSION to 3 and regenerated all 27 history snapshots and the committed api_surface.json; both fixes are documented in tools/api_checker/history/README.md's format-history log. Also fixes diff_api.py's format_version guard, which only compared the two loaded surfaces against each other and never against SURFACE_FORMAT_VERSION (what this build actually understands) -- two surfaces on the same, newer-than-expected format_version would have silently passed the guard. Remaining fixes are the concretely actionable findings from Codacy's review of the new tools/api_checker/ files: unused imports/variables, a stray f-string with no placeholders. Left the docstring-formatting nitpicks (pydocstyle D2xx/D4xx) and generic subprocess-usage notices alone -- the former has no established convention elsewhere in this codebase's Python tooling to conform to, and the latter are inherent to a dev tool that shells out to git/clang with developer-controlled arguments, not user input. Signed-off-by: Niels Lohmann <mail@nlohmann.me> Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-07-11 18:59:19 +02:00
Niels LohmannandClaude Sonnet 5	f23b3c63a2	Add AST-based public API checker and fix documentation gaps it found (#3691 ) Adds tools/api_checker/: extract_api.py derives the public API surface directly from the libclang AST (independent of documentation status), check_docs.py flags public entries missing @sa links (and @sa on non-public ones), diff_api.py does an overload-aware breaking/feature diff between two refs, check_macros.py cross- checks documented macros against #define sites, and snapshot_release.py backfills immutable per-release surface snapshots into tools/api_checker/history/ (v3.1.0 through v3.12.0) so diff_api.py can compare releases without live extraction. POLICY.md documents what counts as public API and what stability is guaranteed. Running this tooling against the current tree found and fixed a real documentation backlog: ~25 new API doc pages (ordered_map's methods, json_sax's ctor/dtor/ operator=, byte_container_with_subtype's comparison operators, several orphaned type aliases), each with a compiled and output-verified example, plus missing @sa comments and stale/incorrect Version History entries on several existing pages (found by diffing consecutive release pairs and checking whether the resulting change was actually reflected in the target page's history section). Also adds docs/home/api_changes.md, a per-release, per-function reference of public API changes (v3.1.0 through v3.12.0) generated from the history/ snapshots, complementing (not replacing) the existing release notes. Along the way, found and fixed several extractor bugs by testing against real release tags rather than trusting the algorithm in isolation -- most notably an identity-key scheme based on libclang's USR that encoded the enclosing class template's own arity, and a since-renamed ABI inline-namespace pattern (json_v3_11_0 vs. today's json_abi_v3_11_2) that neither of two earlier regex attempts stripped correctly. Both are documented in extract_api.py's docstrings and tools/api_checker/history/README.md so the failure mode doesn't recur silently. .github/workflows/check_api_docs.yml runs extract_api.py + check_docs.py in CI, advisory-only for now (documented backlog may not be at zero for entities this PR didn't touch), plus a blocking drift check on the committed tools/api_checker/api_surface.json. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-07-11 18:59:00 +02:00
				`@@ -0,0 +1 @@`
				`Container is std::vector<std::pair<const Key, T>>: true`