deploy: 521a084827

features/binary_formats/cbor.md

@@ -66,7 +66,15 @@ see "binary" cells in the table above.
 
 !!! info "NaN/infinity handling"
 
-    If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the normal JSON serialization which serializes NaN or Infinity to `null`.
+    `NaN`, `Infinity`, and `-Infinity` are serialized as a CBOR half-precision float (type 0xF9, 3 bytes total):
+    `NaN` as `0xF9 0x7E 0x00`, `Infinity` as `0xF9 0x7C 0x00`, and `-Infinity` as `0xF9 0xFC 0x00`. This behavior
+    differs from the normal JSON serialization which serializes NaN or Infinity to `null`.
+
+!!! note
+
+    Prior to version 3.13.0, NaN and Infinity were instead serialized as a CBOR double-precision float (type 0xFB,
+    9 bytes total), because the check used to select a smaller encoding compared magnitudes with NaN, which is
+    always `false` and caused the intended half-precision path to be skipped.
 
 !!! info "Unused CBOR types"
 
@@ -160,6 +168,13 @@ The library maps CBOR types to JSON value types as follows:
      - simple values (0xE0..0xF3, 0xF8)
      - undefined (0xF7)
 
+!!! warning "Negative integer overflow"
+
+    CBOR negative integers (major type 1) are decoded as `-1 - n`. If the encoded magnitude `n` is too large for the
+    result to fit into `number_integer_t` (`std::int64_t` by default), parsing fails with a
+    [`parse_error.112`](../../home/exceptions.md#jsonexceptionparse_error112) exception rather than overflowing
+    silently.
+
 !!! warning "Object keys"
 
     CBOR allows map keys of any type, whereas JSON only allows strings as keys in object values. Therefore, CBOR maps with keys other than UTF-8 strings are rejected.

features/binary_formats/cbor/index.md

@@ -63,7 +63,11 @@ The mapping is **complete** in the sense that any JSON value type can be convert
 
 NaN/infinity handling
 
-If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the normal JSON serialization which serializes NaN or Infinity to `null`.
+`NaN`, `Infinity`, and `-Infinity` are serialized as a CBOR half-precision float (type 0xF9, 3 bytes total): `NaN` as `0xF9 0x7E 0x00`, `Infinity` as `0xF9 0x7C 0x00`, and `-Infinity` as `0xF9 0xFC 0x00`. This behavior differs from the normal JSON serialization which serializes NaN or Infinity to `null`.
+
+Note
+
+Prior to version 3.13.0, NaN and Infinity were instead serialized as a CBOR double-precision float (type 0xFB, 9 bytes total), because the check used to select a smaller encoding compared magnitudes with NaN, which is always `false` and caused the intended half-precision path to be skipped.
 
 Unused CBOR types
 
@@ -178,6 +182,10 @@ The mapping is **incomplete** in the sense that not all CBOR types can be conver
 - simple values (0xE0..0xF3, 0xF8)
 - undefined (0xF7)
 
+Negative integer overflow
+
+CBOR negative integers (major type 1) are decoded as `-1 - n`. If the encoded magnitude `n` is too large for the result to fit into `number_integer_t` (`std::int64_t` by default), parsing fails with a [`parse_error.112`](https://json.nlohmann.me/home/exceptions/#jsonexceptionparse_error112) exception rather than overflowing silently.
+
 Object keys
 
 CBOR allows map keys of any type, whereas JSON only allows strings as keys in object values. Therefore, CBOR maps with keys other than UTF-8 strings are rejected.

features/binary_formats/messagepack.md

@@ -67,8 +67,15 @@ specification:
 
 !!! info "NaN/infinity handling"
 
-    If NaN or Infinity are stored inside a JSON number, they are serialized properly in contrast to the
-    [dump](../../api/basic_json/dump.md) function which serializes NaN or Infinity to `null`.
+    `NaN`, `Infinity`, and `-Infinity` are serialized as a MessagePack float 32 (type 0xCA, 5 bytes total),
+    regardless of magnitude, in contrast to the [dump](../../api/basic_json/dump.md) function which serializes NaN
+    or Infinity to `null`.
+
+!!! note
+
+    Prior to version 3.13.0, NaN and Infinity were instead serialized as a MessagePack float 64 (type 0xCB, 9 bytes
+    total), because the check used to select the smaller float 32 encoding compared magnitudes with NaN, which is
+    always `false` and caused the float 32 path to be skipped.
 
 ??? example
 

features/binary_formats/messagepack/index.md

@@ -64,7 +64,11 @@ The following values can **not** be converted to a MessagePack value:
 
 NaN/infinity handling
 
-If NaN or Infinity are stored inside a JSON number, they are serialized properly in contrast to the [dump](https://json.nlohmann.me/api/basic_json/dump/index.md) function which serializes NaN or Infinity to `null`.
+`NaN`, `Infinity`, and `-Infinity` are serialized as a MessagePack float 32 (type 0xCA, 5 bytes total), regardless of magnitude, in contrast to the [dump](https://json.nlohmann.me/api/basic_json/dump/index.md) function which serializes NaN or Infinity to `null`.
+
+Note
+
+Prior to version 3.13.0, NaN and Infinity were instead serialized as a MessagePack float 64 (type 0xCB, 9 bytes total), because the check used to select the smaller float 32 encoding compared magnitudes with NaN, which is always `false` and caused the float 32 path to be skipped.
 
 Example
 

features/modules.md

@@ -27,6 +27,7 @@ json data = json::parse(f);
 It should be noted that as modules do not export macros, the `nlohmann.json` module will not export any macros.
 
 ## Exported symbols
+
 Only the following symbols are exported from `nlohmann.json`:
 
 - `nlohmann::adl_serializer`
@@ -38,3 +39,21 @@ Only the following symbols are exported from `nlohmann.json`:
 - `nlohmann::to_string`
 - `nlohmann::literals::json_literals::operator""_json`
 - `nlohmann::literals::json_literals::operator""_json_pointer`
+
+Additionally, the following `nlohmann::detail` symbols are exported, solely to work around an MSVC compilation issue
+([#3970](https://github.com/nlohmann/json/issues/3970)). They are implementation details, not part of the public API,
+and should not be used directly:
+
+- `nlohmann::detail::json_sax_dom_callback_parser`
+- `nlohmann::detail::unknown_size`
+
+## Known issues
+
+C++20 modules support is exercised in CI against current GCC and Clang on Ubuntu, and the default MSVC toolset on Windows Server 2022 — there is no documented minimum compiler version, unlike feature-test-macro-gated features such as [`JSON_HAS_RANGES`](../api/macros/json_has_ranges.md).
+
+!!! info "Known compiler issues"
+
+    - **GCC** may emit "redefinition" errors when `#include <nlohmann/json.hpp>` appears in a module preamble together with other imports. This is an upstream GCC bug, not yet resolved as of GCC 16. Workarounds: include `nlohmann/json.hpp` before other `#include`s, use `import nlohmann.json;` instead, or upgrade GCC. ([issue #5103](https://github.com/nlohmann/json/issues/5103))
+    - **MSVC** could fail with `C2039: 'json_sax_dom_callback_parser' is not a member of ... detail`; fixed by exporting the required internal symbols from `json.cppm` (see [Exported symbols](#exported-symbols) above). ([issue #3970](https://github.com/nlohmann/json/issues/3970))
+
+    If you hit a different module-related build failure, search [existing issues](https://github.com/nlohmann/json/issues?q=is%3Aissue+modules) before filing a new one.

features/modules/index.md

@@ -43,3 +43,19 @@ Only the following symbols are exported from `nlohmann.json`:
 - `nlohmann::to_string`
 - `nlohmann::literals::json_literals::operator""_json`
 - `nlohmann::literals::json_literals::operator""_json_pointer`
+
+Additionally, the following `nlohmann::detail` symbols are exported, solely to work around an MSVC compilation issue ([#3970](https://github.com/nlohmann/json/issues/3970)). They are implementation details, not part of the public API, and should not be used directly:
+
+- `nlohmann::detail::json_sax_dom_callback_parser`
+- `nlohmann::detail::unknown_size`
+
+## Known issues
+
+C++20 modules support is exercised in CI against current GCC and Clang on Ubuntu, and the default MSVC toolset on Windows Server 2022 — there is no documented minimum compiler version, unlike feature-test-macro-gated features such as [`JSON_HAS_RANGES`](https://json.nlohmann.me/api/macros/json_has_ranges/index.md).
+
+Known compiler issues
+
+- **GCC** may emit "redefinition" errors when `#include <nlohmann/json.hpp>` appears in a module preamble together with other imports. This is an upstream GCC bug, not yet resolved as of GCC 16. Workarounds: include `nlohmann/json.hpp` before other `#include`s, use `import nlohmann.json;` instead, or upgrade GCC. ([issue #5103](https://github.com/nlohmann/json/issues/5103))
+- **MSVC** could fail with `C2039: 'json_sax_dom_callback_parser' is not a member of ... detail`; fixed by exporting the required internal symbols from `json.cppm` (see [Exported symbols](#exported-symbols) above). ([issue #3970](https://github.com/nlohmann/json/issues/3970))
+
+If you hit a different module-related build failure, search [existing issues](https://github.com/nlohmann/json/issues?q=is%3Aissue+modules) before filing a new one.

features/types/number_handling.md

@@ -63,6 +63,10 @@ In the default [`json`](../../api/json.md) type, numbers are stored as `#!c std:
 number without loss of precision. If this is impossible (e.g., if the number is too large), the number is stored as
 `#!c double`.
 
+Positive integers are stored as `#!c std::uint64_t`, while negative integers are stored as `#!c std::int64_t`. This
+distinction is determined at parse time: if the JSON number has a leading minus sign, it uses signed integer storage;
+otherwise, it uses unsigned integer storage.
+
 !!! info "Notes"
 
     - Numbers with a decimal digit or scientific notation are always stored as `#!c double`.

features/types/number_handling/index.md

@@ -38,6 +38,8 @@ This section describes how this library implements the above number specificatio
 
 In the default [`json`](https://json.nlohmann.me/api/json/index.md) type, numbers are stored as `std::uint64_t`, `std::int64_t`, and `double`, respectively. Thereby, `std::uint64_t` and `std::int64_t` are used only if they can store the number without loss of precision. If this is impossible (e.g., if the number is too large), the number is stored as `double`.
 
+Positive integers are stored as `std::uint64_t`, while negative integers are stored as `std::int64_t`. This distinction is determined at parse time: if the JSON number has a leading minus sign, it uses signed integer storage; otherwise, it uses unsigned integer storage.
+
 Notes
 
 - Numbers with a decimal digit or scientific notation are always stored as `double`.