Add regression test pinning current behavior (CHECK_THROWS_AS) in the null
section of unit-conversions.cpp with detailed comment explaining the C++
language-level cause (std::optional's own converting constructor wins
overload resolution over basic_json::operator T()).
Add a warning callout in conversions.md documenting that direct construction/
assignment of std::optional<T> from JSON null throws type_error 302, with a
clear workaround (use get<std::optional<T>>() or get_to() instead, which
correctly produce std::nullopt).
This is a limitation at the language level: there is no SFINAE path to
distinguish "called from inside std::optional's own constructor" from "direct
call", so fixing it would require breaking changes to operator ValueType().
A permanent fix belongs in the 4.0 type-strictness redesign (#3453).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-Authored-By: Claude Code <noreply@anthropic.com>
* Added NLOHNMANN_JSON_SERIALIZE_ENUM_STRICT
- duplicate of NLOHMANN_JSON_SERIALIZE_ENUM
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* Added failing tests for NLOHMANN_JSON_SERIALIZE_ENUM_STRICT
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* modified NLOHMANN_JSON_SERIALIZE_STRICT to throw
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* added documentation and changed readme to include NLOHMANN_JSON_SERIALIZE_ENUM_STRICT
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* ran amalgamate
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* docs(macros): add page for JSON_SERIALIZE_ENUM_STRICT
- added page to nav
- added links to new page where appropriate
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* refactor(macros): make JSON_SERIALIZE_ENUM_STRICT use JSON_THROW
- added templated wrapper function to fix scope error in calling JSON_THROW
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* refactor(macros): make NLOHMANN_SERIALIZE_ENUM_STRICT use error code 410
- added error code 410 to docs
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* tests(macros): add test for to_json with enum value not mentioned
in mapping for NLOHMANN_JSON_SERIALIZE_ENUM_STRICT
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* Apply suggestions from code review
Co-authored-by: Niels Lohmann <niels.lohmann@gmail.com>
Signed-off-by: Caillin Nugent <nugentcaillin@gmail.com>
* fix(macro): prevent compilation error with -Werror and -Wunused-parameter
with NLOHMANN_JSON_SERIALIZE_ENUM_STRICT
- casted exception to void to avoid warning
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* fix(docs): add link to NLOHMANN_SERIALIZE_ENUM_STRICT docs to exception page
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* docs(macros): add example of exception throwing for NLOHMANN_JSON_SERIALIZE_ENUM_STRICT
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
* refactor(macros): add more in-depth error message to NLOHMANN_JSON_SERIALIZE_ENUM_STRICT
- changed error message to follow style of nlohmann/json#4989
- made description of throw wrapper more general
- updated tests and example of exceptions
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
---------
Signed-off-by: Caillin Nugent <caillinn@student.unimelb.edu.au>
Signed-off-by: Caillin Nugent <nugentcaillin@gmail.com>
Co-authored-by: Niels Lohmann <niels.lohmann@gmail.com>
* Add new macros for named conversions
* Unit tests for the named conversion macros
* Update the docs to include the new macros
* Fix the documentation for the macros
the correct maximum number of member variables is 63
* Fix CI tests
* update the named macros
* move the example files
* update the explicit macros expansion
* update documentation
* fix documentation hiccups
* astyle changes
* add static analysis exceptions
* change md header to explicit html to fit the length
* Small corrections to docs
Co-authored-by: Niels Lohmann <niels.lohmann@gmail.com>
Signed-off-by: George Sedov <radist.morse@gmail.com>
---------
Signed-off-by: George Sedov <radist.morse@gmail.com>
Co-authored-by: Niels Lohmann <niels.lohmann@gmail.com>
* fix: treat single-element brace-init as copy/move
When passing a json value using brace initialization with a single element
(e.g., `json j{someObj}` or `foo({someJson})`), C++ always prefers the
initializer_list constructor over the copy/move constructor. This caused
the value to be unexpectedly wrapped in a single-element array.
This bug was previously compiler-dependent (GCC wrapped, Clang did not),
but Clang 20 started matching GCC behavior, making it a universal issue.
Fix: In the initializer_list constructor, when type deduction is enabled
and the list has exactly one element, copy/move it directly instead of
creating a single-element array.
Before:
json obj = {{"key", 1}};
json j{obj}; // -> [{"key":1}] (wrong: array)
foo({obj}); // -> [{"key":1}] (wrong: array)
After:
json j{obj}; // -> {"key":1} (correct: copy)
foo({obj}); // -> {"key":1} (correct: copy)
To explicitly create a single-element array, use json::array({value}).
Fixes the issue #5074
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
* fix: regenerate amalgamated single_include/nlohmann/json.hpp
- Add missing comment from include/nlohmann/json.hpp explaining the
single-element brace-init fix (issue #5074)
- Fix extra 4-space indentation in embedded json_fwd.hpp section
Regenerated by running: make amalgamate
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
* Revert brace-init semantics change and fix amalgamation
The single-element brace-init change was a breaking change that cannot be accepted upstream. Reverted all related source, test, and doc changes, then regenerated single_include with correct indentation to pass the amalgamation CI check.
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
* Fix: add JSON_BRACE_INIT_COPY_SEMANTICS opt-in macro for issue #5074
Single-element brace initialization wrapping in an array cannot be fixed without breaking existing code. Added JSON_BRACE_INIT_COPY_SEMANTICS as an opt-in macro (default 0) so users can enable copy/move semantics for single-element brace init without affecting anyone relying on the current behavior.
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
* docs: add dedicated macro page and CI test target for JSON_BRACE_INIT_COPY_SEMANTICS
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
* fix: remove compiler-dependent assertions from #5074 regression test
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
* fix: use defined() guard for JSON_BRACE_INIT_COPY_SEMANTICS to satisfy -Wundef
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
* docs: fix section name in json_brace_init_copy_semantics.md to pass style check
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
* docs: move Default definition section before Notes to fix style check order
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
---------
Signed-off-by: Samaresh Kumar Singh <ssam3003@gmail.com>
PR #4873 introduced a safety check in sax_parse functions to catch
nullptr passed as SAX parser object, which had been already annotated by
JSON_HEDLEY_NON_NULL macro.
Compilers (e.g. clang) which respected the non-null annotation tended to
eliminate the safety check completely in optimized builds, while
compilers which did not, compiled the safety check in. This led to
different behaviors accross different compilers/platforms and/or build
types (debug, release).
This commit reverts PR #4873 to remove this discrepancy. Passing null to
non-null annotated parameter is considered to be undefined behavior.
Fixes#5048
Signed-off-by: Richard Musil <risa2000x@gmail.com>
Co-authored-by: Richard Musil <risa2000x@gmail.com>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 👷 fix Windows CI
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Niels Lohmann
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