📡 Fix documentation gaps for 3.13.0 release (todos 138-142)

- Todo 138: Add "Known issues" section to modules.md with compiler-specific troubleshooting (GCC redefinition, MSVC symbol export). Add pointer note to quality_assurance.md.
- Todo 139: Document CBOR/MessagePack half-precision float encoding for NaN/Infinity (0xF9/0xCA with exact byte sequences). Explain pre-3.13.0 double-precision bug mechanism without issue citations.
- Todo 140: Document CBOR negative-integer-overflow rejection (parse_error.112) for magnitudes exceeding int64_t range (already implemented in rev 1).
- Todo 141: Update version history in value.md and operator[].md with behavior-change details, removing issue citations per citation policy (prose is self-contained).
- Todo 142: Global sed replace of 3.12.x → 3.13.0 placeholder across all 20 documentation files.

Revision 2 incorporates feedback to reduce changelog-like issue citations. Only citations that add unique troubleshooting value are retained (#5103 for GCC workaround, #3970 for MSVC symbol export). "Known issues" section follows PR #5252's visual pattern (info admonition with bold-bullet format).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann
2026-07-09 12:45:11 +02:00
parent fe0299545a
commit f67b3de5c4
25 changed files with 73 additions and 24 deletions
+1 -1
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@@ -109,7 +109,7 @@ A UTF-8 byte order mark is silently ignored.
- Added in version 3.0.0.
- Ignoring comments via `ignore_comments` added in version 3.9.0.
- Changed [runtime assertion](../../features/assertions.md) in case of `FILE*` null pointers to exception in version 3.12.0.
- Added `ignore_trailing_commas` in version 3.12.x.
- Added `ignore_trailing_commas` in version 3.13.0.
!!! warning "Deprecation"
+1 -1
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@@ -92,4 +92,4 @@ std::string format_as(const BasicJsonType& j)
## Version history
- Added in version 3.12.x.
- Added in version 3.13.0.
@@ -251,5 +251,6 @@ Strong exception safety: if an exception occurs, the original value stays intact
1. Added in version 1.0.0.
2. Added in version 1.0.0. Added overloads for `T* key` in version 1.1.0. Removed overloads for `T* key` (replaced by 3)
in version 3.11.0.
3. Added in version 3.11.0.
3. Added in version 3.11.0. Fixed in version 3.13.0 to consistently accept `std::string_view`-convertible keys, as
already supported by [`at`](at.md), [`value`](value.md), [`find`](find.md), and other lookup functions.
4. Added in version 2.0.0.
+1 -1
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@@ -235,7 +235,7 @@ Invalid Unicode escapes and unpaired surrogates in the input are reported as
- Overload for contiguous containers (1) added in version 2.0.3.
- Ignoring comments via `ignore_comments` added in version 3.9.0.
- Changed [runtime assertion](../../features/assertions.md) in case of `FILE*` null pointers to exception in version 3.12.0.
- Added `ignore_trailing_commas` in version 3.12.x.
- Added `ignore_trailing_commas` in version 3.13.0.
!!! warning "Deprecation"
+1 -1
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@@ -74,4 +74,4 @@ is thrown. In any case, the original value is not changed: the patch is applied
- Added in version 2.0.0.
- Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
target location has a non-object/non-array parent in version 3.12.x.
target location has a non-object/non-array parent in version 3.13.0.
@@ -71,4 +71,4 @@ function throws an exception.
- Added in version 3.11.0.
- Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
target location has a non-object/non-array parent in version 3.12.x.
target location has a non-object/non-array parent in version 3.13.0.
+1 -1
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@@ -126,7 +126,7 @@ A UTF-8 byte order mark is silently ignored.
- Added in version 3.2.0.
- Ignoring comments via `ignore_comments` added in version 3.9.0.
- Added `ignore_trailing_commas` in version 3.12.x.
- Added `ignore_trailing_commas` in version 3.13.0.
!!! warning "Deprecation"
@@ -54,4 +54,4 @@ provides `<format>`, controlled by the [`JSON_HAS_STD_FORMAT`](../macros/json_ha
## Version history
- Added in version 3.12.x.
- Added in version 3.13.0.
+3 -1
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@@ -184,4 +184,6 @@ changes to any JSON value.
1. Added in version 1.0.0. Changed parameter `default_value` type from `const ValueType&` to `ValueType&&` in version 3.11.0.
2. Added in version 3.11.0. Made `ValueType` the first template parameter in version 3.11.2.
3. Added in version 2.0.2. Extended to work with arrays in version 3.12.x.
3. Added in version 2.0.2. Extended to work with arrays in version 3.13.0, including fixing an issue where resolving
`ptr` through an array unexpectedly threw `out_of_range` instead of returning the resolved element (or
`default_value`, as documented).
+1 -1
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@@ -36,4 +36,4 @@ Constant.
## Version history
- Added in version 3.12.x.
- Added in version 3.13.0.
@@ -32,4 +32,4 @@ Linear in the number of reference tokens in the `json_pointer`.
## Version history
- Added in version 3.12.x.
- Added in version 3.13.0.
@@ -35,4 +35,4 @@ Linear in the number of reference tokens in the `json_pointer`.
## Version history
- Added in version 3.12.x.
- Added in version 3.13.0.
@@ -92,4 +92,4 @@ The default value is `0` (disabled — existing behavior is preserved).
## Version history
- Added in version 3.12.x.
- Added in version 3.13.0.
@@ -44,4 +44,4 @@ The default value is detected based on preprocessor macros such as `#!cpp __cplu
- Added in version 3.10.5.
- Added `JSON_HAS_CPP_23` in version 3.12.0.
- Added `JSON_HAS_CPP_26` in version 3.12.x.
- Added `JSON_HAS_CPP_26` in version 3.13.0.
@@ -38,4 +38,4 @@ When the macro is not defined, the library will define it to its default value.
## Version history
- Added in version 3.12.x.
- Added in version 3.13.0.
@@ -75,4 +75,4 @@ For further information please refer to the corresponding macros without `WITH_N
## Version history
1. Added in version 3.12.x.
1. Added in version 3.13.0.
@@ -102,4 +102,4 @@ inline void from_json(const BasicJsonType& j, type& e);
## Version history
Added in version 3.12.x.
Added in version 3.13.0.
@@ -64,4 +64,4 @@ Linear.
- Added in version 1.0.0.
- Moved to namespace `nlohmann::literals::json_literals` in 3.11.0.
- Added `char8_t*` overload in 3.12.x.
- Added `char8_t*` overload in 3.13.0.
@@ -63,4 +63,4 @@ Linear.
- Added in version 2.0.0.
- Moved to namespace `nlohmann::literals::json_literals` in 3.11.0.
- Added `char8_t*` overload in 3.12.x.
- Added `char8_t*` overload in 3.13.0.
@@ -10,6 +10,8 @@ violations will result in a failed build.
Any compiler with complete C++11 support can compile the library without warnings.
Note: C++20 modules support may hit compiler-specific issues not covered by the general compiler matrix below. See [Modules](../features/modules.md#known-issues) for known issues and workarounds.
- [x] The library is compiled with 50+ different C++ compilers with different operating systems and platforms,
including the oldest versions known to compile the library.
@@ -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.
@@ -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
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@@ -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.
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@@ -326,6 +326,9 @@ An unexpected byte was read in a [binary format](../features/binary_formats/inde
```
[json.exception.parse_error.112] parse error at byte 15: syntax error while parsing BSON binary: byte array length cannot be negative, is -1
```
```
[json.exception.parse_error.112] parse error at byte 9: syntax error while parsing CBOR value: negative integer overflow
```
### json.exception.parse_error.113
@@ -893,7 +896,7 @@ A JSON Patch `add` operation cannot be applied because the target location's par
!!! note
This exception was added in version 3.12.x. Before that, this situation hit an internal assertion (aborting the program in debug builds) or was silently ignored when assertions were disabled.
This exception was added in version 3.13.0. Before that, this situation hit an internal assertion (aborting the program in debug builds) or was silently ignored when assertions were disabled.
## Further exceptions
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@@ -178,7 +178,7 @@ See [this section](../features/types/number_handling.md#number-serialization) on
- Can I use `std::format("{}", j)` on a JSON value?
- Can I use `fmt::format("{}", j)` or `fmt::print("{}", j)` (the [{fmt}](https://github.com/fmtlib/fmt) library) on a JSON value?
`std::format` works out of the box since version 3.12.x, as long as the standard library provides
`std::format` works out of the box since version 3.13.0, as long as the standard library provides
`<format>` (see [`JSON_HAS_STD_FORMAT`](../api/macros/json_has_std_format.md)); see
[`std::formatter<basic_json>`](../api/basic_json/std_formatter.md) for details, including the `#!cpp "{:#}"`
pretty-print spec, indent widths (`#!cpp "{:2}"`), and custom indent characters (`#!cpp "{:.>#}"`).