The local alias that the out-of-range test declared shadows the identical
file-scope one, which GCC's -Wshadow=global turns into an error.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Make std::hash<basic_json> consistent with operator== for numbers
operator== converts between number_integer, number_unsigned, and
number_float before comparing, so json(0), json(0U), and json(0.0)
all compare equal. hash() folded the specific value_t into the
result for each of the three numeric cases, giving each a distinct
hash and breaking the standard Hash requirement that a == b implies
hash(a) == hash(b). A std::unordered_set could therefore hold all
three as separate elements even though they compare equal.
hash() now treats all three numeric variants the same way: it
converts the value to number_float_t and combines it with a single
shared type tag, so any two numbers operator== considers equal hash
identically regardless of which internal type actually holds them.
Updated the accompanying test to check this consistency directly
(including via an actual unordered_set) instead of asserting that 0,
0U, and 0.0 hash differently, since that assumption was the bug.
Also corrected the function's own doc comment and the std::hash API
docs, which described the old behavior as intended.
Fixes#5400
Signed-off-by: Afonso Januário <afonso-januario@hotmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Remove now-unused number_integer_t/number_unsigned_t typedefs in hash()
Merging the three numeric branches into one that only reads
number_float_t left these two aliases unused, which several CI
configurations treat as a build error under -Wunused-local-typedefs.
Signed-off-by: Afonso Januário <afonso-januario@hotmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Mark the unordered_set in the hash regression test const
clang-tidy's misc-const-correctness check flagged it: the set is
never mutated after construction, only read via size().
Signed-off-by: Afonso Januário <afonso-januario@hotmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Normalize -0.0 in number hashes and test range ends
operator== compares numbers exactly since #5459, so equal numbers
share one value and convert to the same number_float_t. Update the
comment accordingly, map -0.0 to 0.0 before hashing (std::hash need
not do that), and test -0.0 and the ends of the integer ranges. Show
hash(0.0) in the docs example and note the change in the version
history.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Clarify hash documentation after review
- Say "may hash differently" for null, false, and numbers, since a
collision across types is possible.
- Name the storage types (signed integer, unsigned integer,
floating-point number) instead of example literals.
- Explain that the hash survives converting an integer to
number_float_t but not the lossy conversion back, and that unequal
numbers may share a hash.
- State that the example hash values are illustrative only and vary by
platform, compiler, compiler version, and library version.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Afonso Januário <afonso-januario@hotmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Afonso Januário <afonso-januario@hotmail.com>
* Stop binary writers overflowing the stack on deep values
to_cbor, to_msgpack, and to_ubjson recurse once per nesting level.
The parser is iterative, so a value the library accepts can crash on
the way back out.
Keep the existing recursive path for the first 128 levels and finish
anything deeper on a heap stack. Output is unchanged. BSON is left
alone because its extra size walk is a separate change.
Rebased onto the value-type output sink. The heap frames now initialize
every member, which is what -Weffc++ was rejecting.
See #5392.
Signed-off-by: ayush-singh-0601 <singhayush062006@gmail.com>
(cherry picked from commit cf65ac438f)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Redesign the iterative binary writers around a shared recursion depth limit
Address the open review on the non-recursive CBOR/MessagePack/UBJSON/BJData
writers (#5518):
- Delete the CBOR array/object prefix helpers; both the recursive and
iterative paths call write_cbor_head(), which already existed on develop.
- MessagePack: share one write_msgpack_array_prefix()/write_msgpack_object_prefix()
helper per container kind between the recursive and iterative paths, both
going through to_msgpack_length() so an over-long container throws
out_of_range.412 identically either way.
- Reuse detail::recursion_depth_limit() instead of a separate constant, the
same bound serializer::dump() and write_bson_document() already use.
- Redesign the frames after bson_frame/dump_frame: only a container with
elements is ever pushed, its header is written at the point it is pushed,
and the iterator is set in the frame's constructor instead of a
default-then-assign two-step with a since-removed "started" flag. The
UBJSON frame keeps only the value pointer, the per-element prefix_required
flag, and the iterator; write_closer and is_object are no longer stored,
since the former is always !use_count (use_count is constant for the whole
document) and the latter follows from value->is_object().
- Factor the BJData ND-array shape check into is_bjdata_ndarray(), used by
both the recursive object case and the iterative pushing logic.
- Give the frame classes the GCC -Weffc++ treatment already used for
diff_frame: a noexcept converting constructor plus the five special members
defaulted with no explicit noexcept.
- Fix two @ref self-references in write_cbor/write_msgpack/write_ubjson's own
doc comments to point at the public to_cbor/to_msgpack/to_ubjson/to_bjdata
API instead.
- The iterative object-key write for CBOR/MessagePack now runs the same
strict-mode check_utf8() against the parent object as diagnostics context
that the recursive path already ran, so the two paths raise identical
diagnostics across the switch-over.
- Rewrite the tests: round trips instead of a bare size check, byte-exact
comparisons against the recursive output at depths around the bound, a
deep object and a BJData ND-array past the bound, a deep discarded value
(type_error.321), and the OSS-Fuzz 566583014 CBOR/MessagePack regression.
BSON is unaffected by this change; it already walks its documents
iteratively and is covered separately by #5553.
Co-authored-by: ayush-singh-0601 <179524189+ayush-singh-0601@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: ayush-singh-0601 <singhayush062006@gmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: ayush-singh-0601 <singhayush062006@gmail.com>
Co-authored-by: ayush-singh-0601 <179524189+ayush-singh-0601@users.noreply.github.com>
* Add a natvis fallback visualizer for detail::json_default_base
Squashed onto develop from:
- Add a type in the natvis template for detail::json_default_base
- Document the json_default_base natvis fallback and regenerate natvis
- Match json_default_base in both its current and 3.12.0 namespace
Co-authored-by: Mihnea Magheru <sakuntalle@yahoo.com>
Signed-off-by: Mihnea Magheru <sakuntalle@yahoo.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Take the natvis template from the PR in the amalgamation check
The check ran generate_natvis.py from a develop checkout, which loads
nlohmann_json.natvis.j2 from its own directory. A PR that changes the
template was therefore checked against develop's template and always
failed. Copy the PR's template next to the develop script before
running it.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Mihnea Magheru <sakuntalle@yahoo.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Mihnea Magheru <sakuntalle@yahoo.com>
* Fix CI on develop after #5585
- test-diagnostics-optimized: -O3 makes GCC's -Winline and
-Wsuggest-attribute=pure/const warnings fire with the ci_test_gcc flag
set; turn them off for this test.
- test-diagnostics-optimized: suppress Clang's -Wexit-time-destructors for
the static table in to_json.
- Infer: raise pulse-max-disjuncts from 20 to 40. With the default,
Pulse loses the stored type in basic_json::replace_value() and reports
false null dereferences of get_ptr() results in unit-pointer_access.cpp.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Ignore Infer's false USE_AFTER_DELETE in ordered_map::erase
Infer's std::string model keeps the buffer of a moved-from string, so the
destroy-and-reconstruct loop in erase(first, last) looks like it destroys a
buffer twice.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Mark throw_on_discarded()'s parameters as used without exceptions
With JSON_NOEXCEPTION, JSON_THROW expands to std::abort(), so Clang's
-Wunused-parameter breaks test-disabled_exceptions (since #5761).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Skip the span_input_adapter sax_parse checks with deleted deprecated functions
The #5676 regression test (#5740) calls the deprecated
sax_parse(span_input_adapter&&, ...), which JSON_DELETE_DEPRECATED_FUNCTIONS
deletes, so ci_test_delete_deprecated_functions failed to build.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fall back to the first entry in test-diagnostics-optimized's to_json
clang-tidy (clang-analyzer-security.ArrayBound) flagged it->second for a
value not in the table. Use the same fallback as
NLOHMANN_JSON_SERIALIZE_ENUM; the test still fails with -Werror=array-bounds
on the headers from before #5585.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix clang-tidy findings in tests from #5762 and #5774
- unit-regression2.cpp (#5762): const/auto for the destroy() test values;
NOLINT the intended copy in check_destroy_edge_case().
- unit-serialization.cpp (#5774): build the expected strings with += instead
of chained operator+ (performance-inefficient-string-concatenation).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
MSVC warns with C5260 that kAlpha and kGamma have internal linkage when
the header is used as a header unit or through a module. JSON_INLINE_VARIABLE
makes them inline variables from C++17 on.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Check in the fuzzers that parsing without exceptions agrees
Each fuzzer driver now also parses its input with allow_exceptions =
false. That call must never throw a parse_error, must return a discarded
value where parsing with exceptions fails, and must return the same value
where it succeeds. Values are compared by their dump(), because NaN is
not equal to itself.
A plain !is_discarded() assertion, as suggested in #3642, would never
fail: the drivers parse with exceptions, so a result can never be
discarded.
tests/fuzzing.md describes the checks and notes that OSS-Fuzz and
CIFuzz already run LeakSanitizer, because their default address
sanitizer includes it.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Use JSON_HAS_RANGE_VIEW_CONVERSION in the range view regression tests
#5728 combined the JSON_HAS_RANGES and MinGW conditions into
JSON_HAS_RANGE_VIEW_CONVERSION, but three test guards still spelled
them out.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Test the serializer's buffers at their boundaries
The dump() indent overflow survived full line coverage because the tests
grew its buffer by only one step. This adds tests that land exactly on,
and one past, the limits of the other two serializer buffers:
- write_buffer (1024 bytes): strings of 1023, 1024 and 1025 bytes at the
top level, and of 1022 and 1023 bytes inside an array, so that both
guards in put_string() are hit at their boundary. Each is checked for
dump() and for stream output.
- string_buffer (512 bytes, flushed when fewer than 13 bytes remain):
runs of two-byte escapes, and a surrogate pair written with 14 bytes of
room, right after a flush, and one escape later.
- The 8-byte bulk scan from the serializer side: 0 to 17 plain bytes
followed by a quote, a control character, or a non-ASCII character.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Test the chunked string and binary reads of all binary formats
The binary readers read strings and binary values in chunks of 4096
bytes. Only CBOR tested lengths around that size. MessagePack, UBJSON,
BJData and BSON now round-trip lengths 0, 1, 4095, 4096, 4097, 8192 and
100000 from vector and pointer input, and must report a truncated
payload as a parse error.
UBJSON reads binary values as arrays of numbers, so it is tested with
strings only. BJData binary values reach the chunked read only in
Draft 3. BON8 decodes strings byte by byte and does not use this path.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Document what is not covered by the API stability guarantee
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Move the API stability guarantee to the roadmap
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Note that exceptions to the API stability rules are documented in the release notes
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
OSS-Fuzz moved its issues from bugs.chromium.org to issues.oss-fuzz.com.
The old link now redirects to the new tracker but drops the project
filter, so it showed every project's issues.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
With JSON_BRACE_INIT_COPY_SEMANTICS enabled, single-element brace
initialization from a JSON value decided whether to copy the value or
build an object by inspecting the value's runtime shape: a two-element
array whose first element is a string, such as ["key", 42], was turned
into an object instead of being copied. This made the behavior depend
on the element's content, and it did not distinguish an existing value
of this shape from a nested braced pair written in the source, such as
the inner {"key", "value"} of {{"key", "value"}}.
json_ref now records whether it was constructed from a braced list
(true only for the std::initializer_list<json_ref> constructor used
for nested braced lists) or from a value. The initializer-list
constructor uses this to copy or move a single non-braced-list element
before deciding whether the list describes an object, so a JSON value
is always copied regardless of its shape, while a braced pair written
in the source still creates an object.
Fixes#5662.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Create a value before giving it its type
Squashed onto develop from:
- Create a value before giving it its type
- Skip the failed-allocation test when exceptions are disabled
- Keep the created pointer rather than an uninitialized json_value
- Skip the vector<bool> failed-allocation check for VS 2015 with iterator debugging
- Test the remaining to_json overloads with a failing allocation
- Skip the to_json allocation-failure section on VS 2015 Debug
- Fix false GCC -Warray-bounds error with JSON_DIAGNOSTICS at -O3 (#5744)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Store the new value with a helper in all to_json constructors
Every external_constructor<>::construct now creates the new value first and
hands it to basic_json::replace_value(), which destroys the old value, stores
the new one before setting its type (as elsewhere in this PR), sets the
parents, and checks the invariant.
The std::vector<bool> and std::valarray overloads use array_t's range
constructor, which the other array overloads already rely on. Range views
keep their loop, as begin() and end() of a view may have different types.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Squashed onto develop from:
- Cut Unicode ill-formed byte sweeps to one representative prefix
- Pin unrelated bytes in the remaining ill-formed UTF-8 sweeps
- Speed up unit-unicode1
- Run the cheap binary format size tests unconditionally
- Compile unit-msgpack.cpp only once
- Check the JSON Pointer roundtrip for every code point again
- Cover every byte class in the ill-formed UTF-8 sweeps
- Merge the Unicode tests into unit-unicode.cpp
- Stop excluding the Unicode tests in CI
Signed-off-by: elix3r <157088510+22elix3r@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: elix3r <157088510+22elix3r@users.noreply.github.com>
Squashed onto develop from:
- Make the json.tar.xz release archive configure standalone
- Update the supported compiler list and the CITATION.cff repository link
- Add json_fwd.hpp to the Bazel singleheader-json target
- Document SwiftPM's #include <json.hpp> form and add CI coverage
- Migrate REUSE metadata from deprecated .reuse/dep5 to REUSE.toml
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add helper types to make it easier to create a basic_json type with modified template parameters
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Rename with_changed_*_t aliases to with_*_t and merge integer/unsigned aliases
Per review discussion on #3898 between gregmarr and nlohmann:
- rename with_changed_X_t to with_X_t for brevity
- replace the separate with_changed_integer_t/with_changed_unsigned_t
aliases with a single with_integers_t<NumberIntegerType2, NumberUnsignedType2>
- add @sa doc comment links for the upcoming documentation page
Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add documentation for the with_*_t member alias templates
Add docs/mkdocs/docs/api/basic_json/with_t.md documenting with_object_t,
with_array_t, with_string_t, with_boolean_t, with_integers_t, with_float_t,
with_allocator_t, with_json_serializer_t, with_binary_t and with_base_class_t,
with an accompanying example, and link the page from the basic_json member
types list and the mkdocs navigation.
Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add tests for the with_*_t member alias templates
Check with std::is_same that each with_*_t alias produces the expected
basic_json type, and that with_string_t keeps nlohmann::ordered_map as
the object type when used on ordered_json.
Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix with_t nav entry and document chaining of the with_*_t aliases
Indent the with_t entry in mkdocs.yml so it is listed under basic_json,
explain that the aliases can be chained and work on ordered_json, and
test both, including json::with_object_t<ordered_map> == ordered_json.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add docset entry for basic_json::with_t
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: barcode <barcode@example.com>
Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
2026-10-07: add the scalar enum labels already handled by the default
branch so -Werror=switch-enum builds succeed. Keep the existing behavior
and synchronize the generated single header.
Signed-off-by: fhgffy <102001626+fhgffy@users.noreply.github.com>
The non-recursive destroy walk from #5762 picked an object's last child
via object_t::rbegin() and std::prev(end()). Neither is available for
every ObjectType: no_key_compare_map in unit-custom-object-type.cpp has
no rbegin(), so develop no longer compiles that test, and hash maps such
as std::unordered_map only have forward iterators.
The walk can take an object's children in any order, as long as it
finds the same child again while the object is not modified in between.
So objects with bidirectional iterators keep using their last child
(O(1) to remove from vector-based maps like ordered_map), and objects
with forward-only iterators use begin() instead. No reverse iteration
or rbegin() is needed any more, and the walk stays allocation-free.
Adds a forward-only ObjectType to the tests, destroyed both with mixed
nesting and 100000 levels deep.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Check for the expected separator before the lexer's token switch
After a key the parser expects ':', after a value usually ','. Test for
that character first instead of going through scan()'s switch, which
compiles to an indirect jump. Any other character takes the old path,
so tokens and error messages are unchanged.
Parsing 6.3% faster with GCC 15.2 and 2.7% with Clang 22.1 (geomean of
the ParseString, ParseFile and ParseIndented benchmarks).
Signed-off-by: Michiel van Slobbe <michiel.van.slobbe@gmail.com>
* Improvement: address PR comments
Signed-off-by: Michiel van Slobbe <michiel.van.slobbe@gmail.com>
* fix: address comments
Signed-off-by: Michiel van Slobbe <michiel.van.slobbe@gmail.com>
* Fix clang-tidy bugprone-signed-char-misuse in scan_expecting
Convert the expected separator through unsigned char before storing it as
char_int_type. The generated code is unchanged.
Signed-off-by: Michiel van Slobbe <michiel.van.slobbe@gmail.com>
* Use raw string literals in the separator comment tests
Signed-off-by: Michiel van Slobbe <michiel.van.slobbe@gmail.com>
---------
Signed-off-by: Michiel van Slobbe <michiel.van.slobbe@gmail.com>
Co-authored-by: Michiel van Slobbe <michiel.van.slobbe@gmail.com>
* Replace retired macOS 14 runner and test all available Xcode versions
GitHub retires the macos-14 image on 2026-11-02 (brownouts from
2026-10-05). Xcode 15 is not available on any remaining hosted
runner, so drop the macos-14 job and its documented compilers.
Also test the Xcode versions that the images provide but CI did not
use (26.1.1-26.3 on macos-15, 26.4.1-26.6 on a new macos-26 job), and
pin GCC 16 explicitly next to gcc:latest.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Document new Xcode and GCC versions in the supported compilers table
Versions taken from the CI logs of this PR (Xcode 26.1.1-26.6) and
from the gcc:16 image (same digest as gcc:16.2.0 and gcc:latest).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Use the provided allocator in destroy() (#4842)
Uses the provided allocator to allocate the stack used to avoid
recursion in the destroy() implementation used by ~basic_json.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Test that the destructor uses the provided allocator
Adds a regression test for #4842: destroying a nested array or object must allocate its temporary stack through the basic_json allocator, not std::allocator.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix allocation failure during JSON destruction
Signed-off-by: Michael Sam <michaelsam94@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Make json_value::destroy() non-recursive and allocation-free
destroy() used to flatten a nested array/object into a heap-allocated
std::vector to avoid recursing per nesting level. That vector could
itself throw bad_alloc under memory pressure, and since it now used the
basic_json's own allocator (#4842), a failing allocator supplied by the
caller made this more likely, not less. An exception thrown from inside
~basic_json(), which is noexcept, terminates the program (#5135).
Replace the vector-based stack with a pointer-reversal walk that visits
the tree without recursing per level and without allocating anything:
cur is the array/object currently being emptied, prev is its parent
(or null at the top). A parent's last child slot doubles as storage for
that parent's own parent link while we are below it, so no extra memory
is needed. A child is only ever removed once it is a scalar or an empty
array/object, which neither allocates nor recurses more than one level
deep. take() moves m_data between these locals directly, bypassing
set_parents()/assert_invariant() (the former is O(#children) per call
under JSON_DIAGNOSTICS, which would make the walk quadratic otherwise).
This also removes the std::vector<basic_json, allocator_type> stack
added by #4842, so the extra allocations it introduced disappear along
with it.
Co-authored-by: Michael Sam <9461037+michaelsam94@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Test that destroy() performs no allocation, even under memory pressure
Update the #4842 regression test: it used to check that destroying a
nested array/object made at least one allocation through the provided
allocator (the old flattening stack). Now that destroy() does not
allocate at all, assert the opposite: zero allocations, deallocations
only.
Rework the #5135 regression test to use a dedicated failing/counting
allocator instead of overriding the process-wide ::operator new and
::operator delete, which affected every allocation in the whole
unit-regression2 binary rather than just the values under test. Keep
the original small repro as one case, and add deep (100000 levels) and
wide-and-deep nested array/object/ordered_json cases, all destroyed
while every further allocation is made to fail: the destructor must
complete without allocating, without throwing, and without leaking.
Co-authored-by: Michael Sam <9461037+michaelsam94@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Refactor destroy() for readability and add edge-case tests
Apply review feedback from Greg Marr on the json_value::destroy()
non-recursive, allocation-free destruction walk (#5135):
- last_child() now uses object->rbegin()->second instead of
std::prev(object->end())->second; pop_last_child() keeps
std::prev(end()) since erase() needs a forward iterator.
- is_empty_container() becomes has_no_children(), a switch that
returns true for every non-container type as well as empty
array/object, simplifying the "scalar or already-empty child"
check at the call site. The local variable `last` is renamed to
`cur_last_ref` for clarity.
- free_container() asserts the array/object is already empty before
freeing it, and the object branches assert the expected type.
- destroy(value_t t) is now a thin dispatcher to destroy_string(),
destroy_binary(), and destroy_container(t), each handling its own
"not initialized" check and sharing the simple cases first in the
switch.
- destroy_container() moves the top-level container into the local
stand-in via a plain swap of the json_value union, instead of a
manual copy plus clearing array/object by hand.
- The "cur has no children and there is no parent" case now frees
cur and returns immediately, so the main loop is a plain
while (true) with no trailing code after it.
Also adds edge-case tests for both json and ordered_json (mixes of
empty/non-empty arrays and objects, container children in first/last
position, single-element chains, top-level empty containers, and
destruction via erase()/assignment), plus a mixed-tree case in the
"destructor performs no allocation" test.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Make the destroy() walk helpers private
They modify basic_json internals without maintaining its invariants and
are only meant for destroy_container(), so they no longer need to be
reachable from the rest of basic_json.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Signed-off-by: Michael Sam <michaelsam94@users.noreply.github.com>
Co-authored-by: Vesko Karaganev <vesko.karaganev@gmail.com>
Co-authored-by: Michael Sam <michaelsam94@users.noreply.github.com>
Co-authored-by: Michael Sam <9461037+michaelsam94@users.noreply.github.com>
* Throw type_error.321 when serializing discarded values to binary formats
The CBOR, MessagePack, UBJSON, BJData, and BSON writers silently
skipped the payload of a value_t::discarded value nested in an array
or object, while still writing its slot in the element/member count
(and, for BSON, its entry header), producing a binary document whose
declared size does not match what was actually written.
Throw type_error.321 instead, for a discarded value anywhere in the
tree, including at the top level.
Rewritten from the original PR against the current (non-recursive
option aside) binary_writer.hpp, which has changed substantially since
this was first proposed; the out_of_range.412 MessagePack size check
and unrelated test reformatting from that PR are dropped as out of
scope here.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Document and test type_error.321 for discarded binary values
Add docs for the new exception (home/exceptions.md and the Exceptions
sections of to_cbor/to_msgpack/to_ubjson/to_bjdata/to_bson) and test
coverage for a discarded value nested in an array or object, nested
deeper, and (for UBJSON/BJData) inside an optimized same-type array,
for each of CBOR, MessagePack, UBJSON, BJData, and BSON. Adjust the
three pre-existing "discarded" tests that asserted the old silent
behavior (empty/short output) to expect type_error.321 instead.
Co-authored-by: ameliabarnabyhub <312084480+ameliabarnabyhub@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: ameliabarnabyhub <ameliabarnabyhub@users.noreply.github.com>
Co-authored-by: ameliabarnabyhub <312084480+ameliabarnabyhub@users.noreply.github.com>
* Fix CI on develop after #5600, #5607, and #5755
- binary_reader: cast the result of -1 - number back to number_integer_t,
because a number_integer_t narrower than int is promoted to int, which
GCC's -Warith-conversion rejects (ci_test_gcc, ci_test_standards_gcc)
- JSON_DELETE_DEPRECATED_FUNCTIONS: declare the deleted stream operators
as function templates at namespace scope, because GCC < 5 rejects deleted
friend functions ("can't initialize friend function") and Clang 7-9 report
a redefinition when a class template has a deleted friend function
- docs: give the examples of JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS "Example:"
titles and add the page to the docset (style_check)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Ignore libstdc++'s <format> sign change in the sanitizer job
libstdc++ 14's <format> initializes a size_t parameter with -1 (GCC bug
119429), so every std::format call fails ci_test_clang_sanitizer under
-fsanitize=integer (test-std-format_cpp20). Exclude only the
implicit-integer-sign-change check and only that header via
-fsanitize-ignorelist.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix the AppVeyor (MSVC 2015-2019) build
- binary_reader: emit_signed/emit_unsigned pass integers that do not fit
the number types to emit_float as long double, because MSVC's <cmath>
has no integer overloads of std::isfinite (C2668 'fpclassify'), from #5607
- scalar comparisons: the friend operators take the JSON type for their
noexcept from their parameter, because MSVC 2015/2017 take basic_json as
the class template there (C3203) and MSVC 2019 16.0 does not see member
types or template parameters, from #5751
- unit-conversions2: skip the !is_nothrow_constructible static_assert for
std::optional on MSVC 2017, which evaluates the conditional noexcept as
true (C2607), from #5754
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Re-amalgamate
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Avoid MSVC 2015's C4800 for enums with underlying type bool
MSVC 2015 warns about any conversion to bool (C4800), even with an
explicit cast, so the enum conversions from #5754 (#5671) failed the
AppVeyor build with /WX. Convert to bool by comparing with zero via the
new detail::bool_aware_static_cast, and keep doctest from printing the
enum in the test.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Skip the #5650 allocator test on MSVC 2015 debug builds
MSVC 2015's debug STL constructs the containers' debug proxies through
the allocator in noexcept constructors, so countdown_allocator's failing
construction crashes test-allocator (SIGSEGV) instead of throwing
std::bad_alloc. Use the guard #5585 uses for the same reason.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Skip deleted-function detection checks on MSVC 2015
MSVC 2015 does not treat selecting a deleted function in decltype as a
substitution failure, so the detection traits in
unit-delete_deprecated_functions (#5755) and the integral-key checks in
unit-element_access2 (#5657) report deleted overloads as callable there.
Calling them still fails to compile. Skip those checks for
_MSC_VER < 1910, and use the stream operators for real in the runtime
section, so MSVC 2015 still compiles them with the macro set.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Split the Visual Studio 2017 AppVeyor jobs in two
The VS 2017 jobs hit AppVeyor's 60-minute limit per job while still
compiling the tests (77 of about 108 test targets after 58 minutes).
They pass /std:c++17 for everything anyway, so build only the C++17
variant of each test (JSON_TestStandards=17), and split the unit test
files across two jobs each with the new JSON_TestShard=<index>/<count>
option, which keeps every <count>-th test file starting at <index>.
The extra variants of single test files are built in shard 0 only.
CMAKE_OPTIONS is no longer quoted in appveyor.yml, so that it can hold
more than one option.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix std::terminate when converting std::optional with MSVC 2017
MSVC 2017 evaluates std::is_nothrow_assignable<json&, const T&> as true
even if T's to_json throws, so to_json(json&, const std::optional<T>&)
was noexcept there and the exception from #5642's test called
std::terminate instead of propagating. Make that conversion never
noexcept on MSVC 2017; all other compilers keep the exact condition.
The static_asserts on the condition are skipped for MSVC 2017; the
runtime check that the exception propagates still runs there.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add JSON_DELETE_DEPRECATED_FUNCTIONS to delete the deprecated functions
Defining JSON_DELETE_DEPRECATED_FUNCTIONS to 1 (or the CMake option
JSON_DeleteDeprecatedFunctions) declares every deprecated function as
deleted instead of deprecated, so that code that is not ready for 4.0.0
no longer compiles. A deleted function still takes part in overload
resolution, so from_*(ptr, len) cannot silently bind len to the strict
parameter of from_*(InputType&&, bool); the roadmap now plans to keep
these overloads deleted in 4.0.0 instead of removing them.
The legacy discarded-value comparison is left to its own macro.
Also update the 4.0 roadmap: add JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
and JSON_DELETE_DEPRECATED_FUNCTIONS to the macro table, add the
from_bjdata/from_bon8 (ptr, len) overloads to the deprecated functions,
document the macro in the migration guide, and fix the docs style check
findings (example titles, missing docset entry for JSON_STRICT_BINARY_UTF8).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Declare each deprecated function once and guard only its body
Instead of repeating every deprecated declaration in an
#if JSON_DELETE_DEPRECATED_FUNCTIONS branch, keep one declaration
(with its deprecation attribute) and switch only between "= delete;"
and the function body. Suggested by @gregmarr in the review.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
from_bon8(ptr, len) and from_bjdata(ptr, len) had no overload for a
pointer and a length, unlike from_cbor/from_msgpack/from_ubjson/
from_bson. The call instead bound to from_*(InputType&&, bool strict),
which read ptr as a NUL-terminated C string via strlen and silently
converted len to the strict flag. Data containing a 0x00 byte was cut
off there; data without one was read past the end of the buffer.
Add a deprecated (ptr, len, strict, allow_exceptions) overload for
each function that forwards to (ptr, ptr + len, ...), matching the
existing deprecated overloads of the other four binary readers. Since
neither function ever had this overload, the deprecation is declared
as of version 3.13.0, the next unreleased version, rather than the
version each function was originally added in.
Fixes#5648.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Store maps with enum keys as objects (opt-in)
Maps with enum keys, such as std::map<E, T>, are stored as arrays of
[key, value] pairs, because enums are not convertible to the string type
of object keys - even if NLOHMANN_JSON_SERIALIZE_ENUM maps them to
strings (#4378).
The new JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS macro stores them as objects
instead, converting each key with the enum's to_json. It applies to any
map-like type with enum keys (std::map with any comparator,
std::unordered_map, ...). A key that does not convert to a string throws
type_error.302, and two keys converting to the same string throw the new
type_error.318, rather than losing an entry. The macro changes the output
of inline functions, so it is part of the ABI tag (_ekmo).
Reading needs no macro: std::map and std::unordered_map with enum keys
are now also read from objects, converting each key with the enum's
from_json. That input was rejected before, and arrays of pairs are still
read, so data written either way can be read.
This supersedes #4531, which first proposed storing these maps as
objects.
Co-authored-by: Muhammad Amir bin Mohamad Ghazaly <amirghaz@umich.edu>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Keep multimaps with enum keys as arrays of pairs
With JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS, is_enum_keyed_map also matched
std::multimap and std::unordered_multimap. Storing them as objects throws
type_error.318 as soon as a key occurs twice, which is the normal case for
a multimap, so such values could no longer be serialized at all once the
macro was enabled, although they are stored losslessly as arrays of
[key, value] pairs without it.
Exclude maps with non-unique keys from is_enum_keyed_map. They are
detected by insert(value_type) returning an iterator rather than a
pair<iterator, bool>. Map-like types without such an insert() are still
treated as before.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Move the default enum-keyed map tests out of unit-conversions.cpp
The Windows clang 20.1.8 job (MinGW, Debug) failed to link
test-conversions_cpp17 with "relocation truncated to fit:
IMAGE_REL_AMD64_REL32 against .rdata": the object file of
unit-conversions.cpp was already close to the limit, and the new
"maps with enum keys" test case pushed it over. windows.yml asks to keep
these objects small by splitting test files.
Move the test case unchanged into unit-enum_keyed_maps_default.cpp,
with the three enums it needs. It still honors a -D flag for
JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS, as before. unit-conversions.cpp
is back to its state on develop.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Build the enum-keyed map test object instead of parsing it
ci_test_diagnostic_positions failed in unit-enum_keyed_maps_default.cpp:
with JSON_DIAGNOSTIC_POSITIONS, a parsed value adds its byte range to
the exception message ("(bytes 0-7) type must be array, but is
object"), so the exact-message checks did not match. Build the object
in memory, like unit-custom-array-type.cpp does.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Muhammad Amir bin Mohamad Ghazaly <amirghaz@umich.edu>
* Handle numbers that do not fit narrow number types in the binary readers
With custom number types narrower than the values in a binary document,
for example basic_json<..., std::int32_t, std::uint32_t, float>, every
binary reader (CBOR, MessagePack, UBJSON, BJData, BSON, BON8) passed the
decoded number to the SAX interface with an implicit conversion: the
integer 5000000000 silently became 705032704, and a finite double such as
1e300 became infinity. The lexer handles the same values in JSON text: an
integer that fits neither integer type is stored as number_float_t, and a
finite number that overflows number_float_t is rejected with
out_of_range.406.
Pass every number read from binary input through three helpers that
apply the lexer's rules:
- emit_signed(): number_integer_t, else number_unsigned_t for a
non-negative value, else number_float_t
- emit_unsigned(): number_unsigned_t, else number_float_t
- emit_float(): out_of_range.406 if a finite value overflows
number_float_t; infinity and NaN are passed on
For consistency, a CBOR negative integer below the range of
number_integer_t is now stored as number_float_t, like a too small
integer in JSON text, instead of being rejected with parse_error.112.
With the default number types, this is the only change in behavior.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix MSVC and clang 3.5 in the narrow number type test
MSVC types 3000000000 and 5000000000 as unsigned long, so
json(-3000000000) triggered C4146 (unary minus on an unsigned type),
which /WX turns into an error. Use LL literals, as elsewhere in the
tests.
clang 3.5 cannot convert the lambdas in the braced initializer of the
format table to function pointers. Use named functions instead.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Check integer-to-float fallbacks for overflow in the binary readers
emit_signed, emit_unsigned, and the CBOR negative integer fallback now
pass their number_float_t fallback through emit_float, so a value that
overflows number_float_t is rejected with out_of_range.406 like a
floating-point value, instead of silently becoming infinity. This only
matters for a number_float_t that cannot represent 2^64, such as a
half-precision type. The CBOR value -1 - n is computed as long double so
that emit_float sees a finite value.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Use the input_format member instead of passing the format to binary_reader helpers
The helpers (get_number, get_to, get_string, get_binary, get_bytes,
emit_signed, emit_unsigned, emit_float, unexpect_eof, exception_message)
are members of binary_reader, which already stores the format it was
constructed with, so the parameter was redundant.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Keep the serializer conversion for objects whose keys cannot be converted
#5591 added a test converting nlohmann::json into a basic_json whose
string type cannot be constructed from std::string. That instantiates
convert_iteratively(), whose members.emplace_back(next.key(), ...) needs
exactly that key conversion, and broke the build of unit-alt-string.
Dispatch on the key's constructibility and leave such conversions to the
serializers, as the levels above the nesting bound already do (#3425).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix the remaining CI failures on develop
- unit-wstring: with a 16-bit wchar_t (Windows), a lone surrogate is
reported as the ill-formed byte 0xFF since #5704; the std::wstring
expectations still had the previous <U+0000>.
- ci_single_binaries: json_literals.hpp (#5610) and json.hpp include each
other on purpose, and IWYU, not following the cycle, asks to replace
json.hpp with json_fwd.hpp. Report its findings without failing the
build, as already done for json.hpp.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix the library warnings and noexcept specifications from the merged PRs
- binary_reader: rename the error_handler constructor parameter, which
shadowed the member (-Wshadow, -Wshadow-field-in-constructor; #5746)
- basic_json(copy_construct_tag, ...): declare it noexcept when copying
the base class is (GCC 16 -Wnoexcept; #5690)
- the scalar-on-left legacy comparison operators: noexcept only when
converting the scalar is, like their member counterparts (#5682, #5751)
- compare_leaves: use std::is_eq/is_lt/is_gt instead of comparing a
std::partial_ordering with 0 (-Wzero-as-null-pointer-constant; #5686)
- serializer: silence MSVC C4127 for the EnsureAscii template parameter
(#5741, #5746)
- clang-tidy: return the sanitized reference in binary_writer, take the
key of ordered_map::find_impl by const reference (#5727), and mark the
switches over parse_array_index (#5728)
- ordered_map: keep <memory> for std::allocator (IWYU)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Split unit-conversions.cpp so MinGW can link it
clang 18 with the MinGW linker failed to link test-conversions_cpp17
("relocation truncated to fit: IMAGE_REL_AMD64_REL32"). As windows.yml
recommends, keep the objects small by splitting the test file.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix the tests added by the merged PRs for all CI configurations
- discard the results of dump() and from_*() in CHECK_THROWS with
utils::ignore_return_value (GCC -Werror=unused-result)
- give unit-bson's huge_string_t a default constructor (MSVC C2512,
GCC 5, clang 3.5)
- unit-disabled_exceptions: use the literals namespace when the global
UDLs are off (ci_test_noglobaludls; #5700)
- unit-binary_utf8_strict: expect the JSON pointer prefix with
JSON_DIAGNOSTICS (#5741)
- skip the tests that rely on exceptions under JSON_NOEXCEPTION
(#5678, #5732)
- clang-tidy and clang -Werror: static test data, CAPTURE(...);,
const-correctness, use-after-move alias, unused conversion operator,
a missing <iterator> include
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Title the macro examples and add JSON_STRICT_BINARY_UTF8 to the docset
The documentation style check requires "Example: ..." titles on pages with several examples (#5741, #5591) and a docset entry for every macro page.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Regenerate BUILD.bazel and nlohmann_json.natvis
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
#5746 added detail/output/error_handler.hpp and #5741 the json_abi_sbu8 ABI tag.
* Install libidn11 for the CMake 3.5.0 binary in ci_cmake_flags
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
#5733 moved ci_cmake_options from ubuntu:focal to ubuntu:24.04, which no longer ships libidn.so.11; the CMake 3.5.0 release binary links against it, so every ci_cmake_flags run has failed since. Install focal's libidn11 package for that matrix entry only.
* Suppress Infer's false STACK_VARIABLE_ADDRESS_ESCAPE in get_impl
get_impl() returns its local by value. A test added by the merged PRs instantiates it with a type Infer misreads, so ci_infer reported the 2021 code for the first time.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Document options to reduce compile times
Add an integration page that collects the ways to reduce compile times
with measurements: json_fwd.hpp in headers, JSON_NO_AUTOMATIC_UDLS,
explicit instantiation with extern template, modules, and precompiled
headers, and notes that JSON_NO_IO and JSON_USE_GLOBAL_UDLS have no
measurable effect.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Include only json_literals.hpp in the JSON_NO_AUTOMATIC_UDLS examples
json_literals.hpp includes json.hpp itself, so including both is redundant.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add basic_json::as_base_class and document name conflicts with custom base classes
Members of basic_json hide members of a custom base class with the same
name, and future releases may add members that hide ones accessible
today. Document this in json_base_class_t and add as_base_class() to
reach hidden members without spelling out the cast.
Also make json_base_class_t a public member type. It was documented
since 3.12.0, but declared private, so users could not name it.
Supersedes #3899.
Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add as_base_class to the docset search index
New public members get an entry in docs/docset/docSet.sql (as done for
to_bon8/from_bon8 in #2998). Without it, the Dash/Zeal docset built from
the documentation cannot find basic_json::as_base_class.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Silence clang-tidy for the hidden type_name() in the base class test
ci_clang_tidy failed with readability-convert-member-functions-to-static
on base_class_with_hidden_members::type_name(). It must stay a
non-static member: the test shows that it is hidden by the non-static
basic_json::type_name() and reachable through as_base_class().
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
* Document the macros that preview version 4.0 in the roadmap
List the macros that guard breaking changes planned to become the
default in version 4.0.0, and explain that 4.0.0 will be the sum of
these opt-in flags, which can be tried on the 3.x release train.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* List the deprecated functions removed in 4.0 in the roadmap
The roadmap lists what will be removed; the migration guide keeps the
examples for how to replace each item. Also mention the deprecated
(ptr, len) overloads of the from_* functions in the migration guide.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Wrap overlong line in cbor_tag_handler_t documentation
The line added in #5559 exceeds the 160-character limit enforced by the
documentation style check.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON to the 4.0 example
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add JSON_STRICT_BINARY_UTF8 to the 4.0 roadmap
The macro comes from #5741: the CBOR, UBJSON, BJData, and BSON writers keep writing ill-formed UTF-8 unchanged in 3.x and are planned to check it by default in 4.0.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
The wide-string input adapter (used for std::u16string, std::u32string,
std::wstring, and iterators over 2- or 4-byte character types) passed
some malformed code units on to the lexer as values that are neither a
byte (0x00..0xFF) nor char_traits<char>::eof(). As a result:
- A lone UTF-16 surrogate inside true/false/null was accepted if its low
byte matched the expected letter, or ended the input silently if it
was the last unit.
- A high surrogate followed by a unit that is not its low surrogate
swallowed that unit; if the swallowed unit was the newline ending a
// comment, the comment silently extended over the next line.
- Where wint_t is a signed int (macOS, the BSDs), a negative wchar_t
collided with char_traits<char>::eof() (ending the input early) or was
truncated to its low byte, depending on its value.
The UTF-32 helper now converts the code unit to std::uint32_t before the
range checks, so a negative unit reaches the same "emit 0xFF" branch
already used for code points above U+10FFFF. The UTF-16 helper now
peeks at the next unit before consuming it, and emits 0xFF instead of
the raw surrogate when no valid pair is found, matching how ill-formed
UTF-8 bytes are rejected elsewhere in the lexer.
Fixes#5645.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>