JSON_USE_SIMDUTF was documented and shipped but never compiled by anything in
the repository, so nothing held the backend to the behavior the docs promise.
Add JSON_TestSimdutf (OFF by default), which fetches simdutf and defines
JSON_USE_SIMDUTF for every test target, and a ci_test_simdutf target that runs
the whole suite in that configuration. Because simdutf needs C++17, the suite is
built at C++11 as well, so one job covers both the scalar fallback with the
macro defined and simdutf itself.
The dependency hangs off test_main, whose usage requirements every test target
inherits. The library target and the installed CMake package are deliberately
untouched: making nlohmann_json link simdutf would put a find_dependency() in
the exported package, which is a separate decision.
Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MXDi7NTMKAmoArUZSKMc4T
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
simdutf.h rejects anything below C++17 with an #error, so defining
JSON_USE_SIMDUTF in a C++11 or C++14 translation unit did not fail with a
message about simdutf being unavailable - it failed to compile at all, taking
the library's C++11 support with it. Nothing caught this because no build ever
compiled that path.
Gate the include and both uses on JSON_HAS_CPP_17, the same way number_parse.hpp
gates std::from_chars. Below C++17 the macro now has no effect and the scalar
validator runs; it accepts and rejects exactly the same input, so the macro is
safe to set project-wide even when some translation units use an older standard.
Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MXDi7NTMKAmoArUZSKMc4T
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
string_bulk_run() had the same `return scalar_string_bulk_run(...)` in both
arms of the `#if`. The simdutf arm already falls through when validation
fails, so a single return after the `#endif` says the same thing.
The JSON_USE_SIMDUTF example showed `#include <simdutf.h>`, which
string_scan.hpp already does under the same guard; users only have to put the
header on the include path and link the library, not include it themselves.
Set the version history entry to 3.13.0, matching the other macro pages
documenting unreleased features.
Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MXDi7NTMKAmoArUZSKMc4T
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
The macro was only listed in the API macro index; add it to the supported
macros overview alongside the other JSON_USE_* macros, and note that it
selects between two definitions of the same inline function and so must be
defined identically in every translation unit.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
The bulk string scanner validates UTF-8 straight from a contiguous buffer.
The scalar validator caps at ~0.3-0.7 GB/s on non-ASCII text; a SIMD
validator reaches several GB/s. Rather than hand-rolling SIMD UTF-8
validation (easy to get subtly wrong - a from-scratch SSE attempt rejected
valid CJK), wire in the vetted simdutf library behind an opt-in switch.
simdutf is not header-only (it ships simdutf.cpp and uses runtime CPU
dispatch), so it is not vendored: defining JSON_USE_SIMDUTF includes
<simdutf.h> and routes the bulk validator through simdutf::validate_utf8;
the project supplies and links simdutf. Undefined (the default), nothing
external is included and the portable C++11 scalar path is used, so the
library stays header-only and its baseline behavior is unchanged.
Design keeps behavior identical either way:
- scan_string_bulk() now finds the run up to the next quote/escape/control
byte (non-ASCII allowed) and validates it in one shot; on the rare
validation failure it recomputes the exact valid prefix with the scalar
helper, so ill-formed input still falls through to the byte path and is
reported at the same position with the same message.
- the per-sequence scalar path is factored into scalar_string_bulk_run()
and is the default backend; the refactor is behavior-preserving and does
not change scalar throughput.
Verified: default and JSON_USE_SIMDUTF builds accept/reject/parse
identically across 2,000,000 arbitrary-byte documents and 1,000,000
mixed-escape/UTF-8 documents (differential fuzz vs the streaming byte
path); lexer/parser/diagnostic-position/deserialization suites pass under
both configurations (20,188 assertions with the backend enabled);
warning-clean on g++ and clang, C++11 and C++20, both configurations.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AXcDtEma2PjxgmPS9cQGzA
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Closes#3106. set(JSON_Diagnostics ON) before find_package() has no
effect on a package built and installed elsewhere (Homebrew, vcpkg, a
system package, etc.) -- the compile definition is baked into the
exported nlohmann_jsonTargets.cmake at install time and the generated
config script never re-reads that variable. Verified empirically
against the real Homebrew-installed 3.12.0 package: the exported
target carries a fixed $<$<BOOL:OFF>:JSON_DIAGNOSTICS=1>, and the
suggested set(JSON_Diagnostics ON) snippet produces no change in
exception output.
Documents the actual working fix (overriding the imported target's
INTERFACE_COMPILE_DEFINITIONS property after find_package()) and the
multi-target "JSON_DIAGNOSTICS redefined" pitfall reported earlier in
the issue thread.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
* 📝 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>
PR #5248 added a 5th JSON_HAS_RANGES exclusion branch to
macro_scope.hpp (nvcc CUDA 12.0.x/12.1.x, fixed in 12.2, issue #3907)
shortly after #5252 added the "Known compiler/stdlib exclusions"
list to json_has_ranges.md, so the new branch was missing from the
just-added doc section. Bring the list back to parity with the code
(5 exclusion branches, 5 documented).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 📝 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>
* 📝 Document integer type selection, type_name() invalid value, and std::optional get() fix
- number_handling.md: clarify that positive/negative integers select
unsigned/signed storage based on the leading minus sign (todo 143).
- type_name.md: document the new "invalid" return value for corrupted
JSON values (todo 145).
- get.md: note that get<std::optional<T>>() was unreachable in every
configuration prior to 3.13.0 due to an internal macro-guard bug,
unrelated to JSON_USE_IMPLICIT_CONVERSIONS's actual effect (todo 144).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 📝 Document compiler/stdlib exclusions in macro_scope.hpp
Add "Known compiler/stdlib exclusions" subsections to the public documentation for
JSON_HAS_FILESYSTEM and JSON_HAS_RANGES, listing the exact compiler/stdlib versions
that are silently excluded even when feature-test macros indicate support. Each
exclusion references the originating issue. Also add a pointer note in the compiler
compatibility section linking to these details.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-Authored-By: Claude Code <noreply@anthropic.com>
* 💚 fix build
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
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>
* Support any basic_json type in NLOHMANN_DEFINE_TYPE_* macros
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Test NLOHMANN_DEFINE_TYPE_* macros also support unordered_json
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Simplify test about NLOHMANN_DEFINE_TYPE_ with many arguments
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Remove extra scope in macros tests
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Remove unused test class in macros tests
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Update documentation about NLOHMANN_DEFINE_TYPE_* macros
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Fix NLOHMANN_JSON_SERIALIZE_ENUM documentation
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Mark some variables const in macros tests, fixes clang-tidy
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Workaround clang 3.5 issue with const object initialization
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Update highlighted lines in NLOHMANN_DEFINE_TYPE_* macros examples
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Fix swapped macros in documentation
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Remove extra backslashes at the end of macros
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Require basic_json type in NLOHMANN_DEFINE_TYPE_* generated functions
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Fix typos in macros documentation
Signed-off-by: kimci86 <kimci86@hotmail.fr>
---------
Signed-off-by: kimci86 <kimci86@hotmail.fr>
* Add implementation to retrieve start and end positions of json during parse
* Add more unit tests and add start/stop parsing for arrays
* Add raw value for all types
* Add more tests and fix compiler warning
* Amalgamate
* Fix CLang GCC warnings
* Fix error in build
* Style using astyle 3.1
* Fix whitespace changes
* revert
* more whitespace reverts
* Address PR comments
* Fix failing issues
* More whitespace reverts
* Address remaining PR comments
* Address comments
* Switch to using custom base class instead of default basic_json
* Adding a basic using for a json using the new base class. Also address PR comments and fix CI failures
* Address decltype comments
* Diagnostic positions macro (#4)
Co-authored-by: Sush Shringarputale <sushring@linux.microsoft.com>
* Fix missed include deletion
* Add docs and address other PR comments (#5)
* Add docs and address other PR comments
---------
Co-authored-by: Sush Shringarputale <sushring@linux.microsoft.com>
* Address new PR comments and fix CI tests for documentation
* Update documentation based on feedback (#6)
---------
Co-authored-by: Sush Shringarputale <sushring@linux.microsoft.com>
* Address std::size_t and other comments
* Fix new CI issues
* Fix lcov
* Improve lcov case with update to handle_diagnostic_positions call for discarded values
* Fix indentation of LCOV_EXCL_STOP comments
* fix amalgamation astyle issue
---------
Co-authored-by: Sush Shringarputale <sushring@linux.microsoft.com>
* Move UDLs into nlohmann::literals::json_literals namespace
* Add 'using namespace' to unit tests
* Add 'using namespace' to examples
* Add 'using namespace' to README
* Move UDL mkdocs pages out of basic_json/
* Update documentation
* Update docset index
* Add JSON_GlobalUDLs CMake option
* Add unit test
* Build examples without global UDLs
* Add CI target
* Add versioned inline namespace
Add a versioned inline namespace to prevent ABI issues when linking code
using multiple library versions.
* Add namespace macros
* Encode ABI information in inline namespace
Add _diag suffix to inline namespace if JSON_DIAGNOSTICS is enabled, and
_ldvcmp suffix if JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON is enabled.
* Move ABI-affecting macros into abi_macros.hpp
* Move std_fs namespace definition into std_fs.hpp
* Remove std_fs namespace from unit test
* Format more files in tests directory
* Add unit tests
* Update documentation
* Fix GDB pretty printer
* fixup! Add namespace macros
* Derive ABI prefix from NLOHMANN_JSON_VERSION_*
* Add C++20 3-way comparison operator and fix broken comparisons
Fixes#3207.
Fixes#3409.
* Fix iterators to meet (more) std::ranges requirements
Fixes#3130.
Related discussion: #3408
* Add note about CMake standard version selection to unit tests
Document how CMake chooses which C++ standard version to use when
building tests.
* Update documentation
* CI: add legacy discarded value comparison
* Fix internal linkage errors when building a module
Niels LohmannandClaude
Caillin NugentandNiels Lohmann
George SedovandNiels Lohmann
SamareshSingh
Andy Choi
Harinath Nampally
kimci86
Greg Marr
Einars Netlis-Galejs
Sushrut ShringarputaleandSush Shringarputale
Niccolò IardellaandNiccolò Iardella
alferov
Vyacheslav Zhdanovskiy
Vyacheslav Zhdanovskiy
Noandtusooa
tocic
Florian Albrechtskirchinger
Richard Hozák
