Fix documentation gaps found in a full GitHub Discussions review (#5264)

* 📝 Fix documentation gaps found in a full GitHub Discussions review Reviewed all 1008 GitHub Discussions (2020-2026) for recurring questions that better or more visible documentation would have avoided. Adds/expands documentation for ~26 distinct gaps, including: - New "Debugging" page collecting natvis, GDB pretty printer, LLDB status, and JSON_DIAGNOSTICS pointers (previously scattered/undiscoverable) - Thread-safety and schema-validation FAQ entries - StringType's char-based requirement (no wstring/u16string/u32string) - Brace-initialization-yields-arrays warning directly on the constructor reference page (previously only in the FAQ, missed by users reading the constructor docs) - std::any exclusion from get<T>(), with a manual-dispatch example - Non-string-keyed std::map serializing as an array of pairs - ordered_json compatibility with NLOHMANN_DEFINE_TYPE_* macros (already worked, was undocumented) - std::array truncation on size-mismatched conversion (no exception) - static_cast vs. get<std::optional<T>>() divergence - Recipe for omitting a std::optional field instead of emitting null - No built-in nesting-depth limit during parsing + a callback-based workaround recipe - Recipe for streaming a large homogeneous array via parser callbacks - operator>> stream-position semantics for concatenated JSON values - JSON Pointer array-vs-object creation rule for non-existing paths - CMake target name (nlohmann_json_modules) needed to link C++20 modules - ESP-IDF/PlatformIO: no official package, link to a community fork - get(key, default) as the Python dict.get() equivalent - reserve() recipe for pre-allocating array capacity - JSONC as an alias for the existing ignore_comments/ignore_trailing_commas combination (distinct from the unsupported JSON5) - items() dereferenced-element type: decltype() idiom + detail-namespace stability caveat - Various macro/type-conversion limitations (MSGPACK_DEFINE_ARRAY equivalent, char-array round-tripping, ADL serializer macro gap) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * 🎨 fix format Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-01 22:17:15 +00:00 · 2026-07-10 16:01:08 +02:00
parent b630f5e9c7
commit e9c3985f0a
23 changed files with 367 additions and 3 deletions
@@ -11,7 +11,7 @@ This library does not support comments *by default*. It does so for three reason

 3. It is dangerous for interoperability if some libraries add comment support while others do not. Please check [The Harmful Consequences of the Robustness Principle](https://tools.ietf.org/html/draft-iab-protocol-maintenance-01) on this.

-However, you can set parameter `ignore_comments` to `#!cpp true` in the [`parse`](../api/basic_json/parse.md) function to ignore `//` or `/* */` comments. Comments will then be treated as whitespace.
+However, you can set parameter `ignore_comments` to `#!cpp true` in the [`parse`](../api/basic_json/parse.md) function to ignore `//` or `/* */` comments. Comments will then be treated as whitespace. Combined with `ignore_trailing_commas` (also a `parse` parameter), this covers what is commonly referred to as **JSONC** (JSON with Comments, as used e.g. by Visual Studio Code's `.jsonc` files) -- comments and trailing commas, nothing more. This is a different, smaller extension than [JSON5](https://json5.org), which additionally allows unquoted keys, single-quoted strings, and other syntax changes that this library does not support.

 For more information, see [JSON With Commas and Comments (JWCC)](https://nigeltao.github.io/blog/2021/json-with-commas-comments.html).