Merge branch 'develop' into custom-number-type-fixes

Resolve the out_of_range.407 entry in exceptions.md: keep the list of formats
and ranges from this branch and the "Former occurrences" note from develop.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

docs/mkdocs/docs/api/basic_json/array_t.md

@@ -27,7 +27,7 @@ To store objects in C++, a type is defined by the template parameters explained
 
 ### Default type
 
-With the default values for `ArrayType` (`std::vector`) and `AllocatorType` (`std::allocator`), the default value for
+With the default values for `ArrayType` (`std::vector`) and `AllocatorType` (`std::allocator`), the default type for
 `array_t` is:
 
 ```cpp

docs/mkdocs/docs/api/basic_json/boolean_t.md

@@ -23,7 +23,7 @@ To store boolean values in C++, a type is defined by the template parameter  `Bo
 
 ### Default type
 
-With the default values for `BooleanType` (`#!cpp bool`), the default value for `boolean_t` is `#!cpp bool`.
+With the default values for `BooleanType` (`#!cpp bool`), the default type for `boolean_t` is `#!cpp bool`.
 
 ### Storage
 

docs/mkdocs/docs/api/basic_json/is_number_unsigned.md

@@ -6,9 +6,6 @@ constexpr bool is_number_unsigned() const noexcept;
 
 This function returns `#!cpp true` if and only if the JSON value is an unsigned integer number. This excludes
 floating-point and signed integer values.
-
-If [`number_unsigned_t`](number_unsigned_t.md) is the same type as [`number_integer_t`](number_integer_t.md), every
-integer is stored as `number_integer_t`, and this function always returns `#!cpp false`.
     
 ## Return value
 

docs/mkdocs/docs/api/basic_json/number_float_t.md

@@ -35,7 +35,7 @@ type to use.
 
 ### Default type
 
-With the default values for `NumberFloatType` (`double`), the default value for `number_float_t` is `#!cpp double`.
+With the default values for `NumberFloatType` (`double`), the default type for `number_float_t` is `#!cpp double`.
 
 ### Default behavior
 
@@ -52,8 +52,9 @@ With the default values for `NumberFloatType` (`double`), the default value for
 > interoperability can be achieved by implementations that expect no more precision or range than these provide, in the
 > sense that implementations will approximate JSON numbers within the expected precision.
 
-This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note that
-numbers smaller than `-1.79769313486232e+308` or greater than `1.79769313486232e+308` are rejected during parsing with
+This implementation does exactly follow this approach, as it uses double precision floating-point numbers by default.
+Note that with the default `double`, numbers smaller than `-1.79769313486232e+308` or greater than
+`1.79769313486232e+308` are rejected during parsing with
 [`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406). Non-finite values (NaN and infinity) can
 only be stored by assigning them directly and are serialized to `null`.
 

docs/mkdocs/docs/api/basic_json/number_integer_t.md

@@ -31,7 +31,7 @@ to use.
 
 ### Default type
 
-With the default values for `NumberIntegerType` (`std::int64_t`), the default value for `number_integer_t` is
+With the default values for `NumberIntegerType` (`std::int64_t`), the default type for `number_integer_t` is
 `#!cpp std::int64_t`.
 
 ### Default behavior

docs/mkdocs/docs/api/basic_json/number_unsigned_t.md

@@ -25,15 +25,14 @@ the type to use.
 `NumberUnsignedType`
 :   the type to store unsigned integers. It must be an **unsigned integral** type (`#!cpp std::is_integral`) with a
     `#!cpp std::numeric_limits` specialization, and it must be able to represent the absolute value of every
-    [`number_integer_t`](number_integer_t.md) value. Alternatively, it can be the same type as
-    [`number_integer_t`](number_integer_t.md); then every integer is stored as `number_integer_t`. See
+    [`number_integer_t`](number_integer_t.md) value. See
     [Template Parameter Requirements](../../features/types/template_parameters.md#numberintegertype-and-numberunsignedtype).
 
 ## Notes
 
 ### Default type
 
-With the default values for `NumberUnsignedType` (`std::uint64_t`), the default value for `number_unsigned_t` is
+With the default values for `NumberUnsignedType` (`std::uint64_t`), the default type for `number_unsigned_t` is
 `#!cpp std::uint64_t`.
 
 ### Default behavior
@@ -90,4 +89,3 @@ Integer number values are stored directly inside a `basic_json` type.
 ## Version history
 
 - Added in version 2.0.0.
-- Can be the same type as `number_integer_t` since version 3.13.0.

docs/mkdocs/docs/api/basic_json/object_t.md

@@ -36,7 +36,7 @@ To store objects in C++, a type is defined by the template parameters described
 ### Default type
 
 With the default values for `ObjectType` (`std::map`), `StringType` (`std::string`), and `AllocatorType`
-(`std::allocator`), the default value for `object_t` is:
+(`std::allocator`), the default type for `object_t` is:
 
 ```cpp
 // until C++14

docs/mkdocs/docs/api/basic_json/string_t.md

@@ -32,7 +32,7 @@ JSON class into byte-sized characters during deserialization.
 
 ### Default type
 
-With the default values for `StringType` (`std::string`), the default value for `string_t` is `#!cpp std::string`.
+With the default values for `StringType` (`std::string`), the default type for `string_t` is `#!cpp std::string`.
 
 ### Encoding
 

docs/mkdocs/docs/api/basic_json/to_bjdata.md

@@ -123,4 +123,6 @@ Linear in the size of the JSON value `j`.
   that is not valid UTF-8 unchanged, as before; `strict` (the default if
   [`JSON_STRICT_BINARY_UTF8`](../macros/json_strict_binary_utf8.md) is enabled) throws `type_error.316`.
 - Throws `type_error.321` for a discarded value since version 3.13.0; previously, a discarded value nested in an
-  array or object was silently skipped, producing invalid BJData.
+  array or object was silently skipped, producing invalid BJData.
+- Writes unsigned integers wider than 64 bits as high-precision numbers since version 3.13.0; previously, they were
+  silently truncated to 64 bits.

docs/mkdocs/docs/api/basic_json/to_bon8.md

@@ -37,8 +37,9 @@ With (2), the bytes written before the exception remain in the output adapter.
 
 ## Exceptions
 
-- Throws [out_of_range.407](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains an unsigned integer
-  above 9223372036854775807, which BON8 cannot represent
+- Throws [out_of_range.407](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains an integer outside
+  the range of int64 (an unsigned integer above 9223372036854775807, or, with a number type wider than 64 bits, any
+  integer beyond int64), which BON8 cannot represent
 - Throws [type_error.316](../../home/exceptions.md#jsonexceptiontype_error316) if `j` contains a string that is not
   valid UTF-8
 - Throws [type_error.321](../../home/exceptions.md#jsonexceptiontype_error321) if `j` or a value nested in it is

docs/mkdocs/docs/api/basic_json/to_bson.md

@@ -47,6 +47,10 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
 
 - Throws [`type_error.317`](../../home/exceptions.md#jsonexceptiontype_error317) if the top-level type of the JSON value
   is not an object; example: `"to serialize to BSON, top-level type must be object, but is string"`
+- Throws [`out_of_range.407`](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains a signed integer
+  outside the range of int64 or an unsigned integer outside the range of uint64, which is only possible with a number
+  type wider than 64 bits; example:
+  `"integer number 9223372036854775808 cannot be represented by BSON as it does not fit int64"`
 - Throws [`out_of_range.409`](../../home/exceptions.md#jsonexceptionout_of_range409) if a key in the JSON object contains
   a null byte (code point U+0000); example: `"BSON key cannot contain code point U+0000 (at byte 2)"`
 - Throws [`out_of_range.412`](../../home/exceptions.md#jsonexceptionout_of_range412) if the length of a document, array,
@@ -119,3 +123,5 @@ pass before anything is written.
   that is not valid UTF-8 unchanged, as before; `strict` (the default if
   [`JSON_STRICT_BINARY_UTF8`](../macros/json_strict_binary_utf8.md) is enabled) throws `type_error.316` before anything
   is written.
+- Throws `out_of_range.407` for integers that do not fit 64 bits since version 3.13.0; previously, integers of a
+  number type wider than 64 bits were silently truncated.

docs/mkdocs/docs/api/basic_json/to_cbor.md

@@ -46,6 +46,9 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
 
 ## Exceptions
 
+- Throws [`out_of_range.407`](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains an integer
+  outside [-2^64, 2^64-1], which is only possible with a number type wider than 64 bits; example:
+  `"integer number 18446744073709551616 cannot be represented by CBOR as it does not fit [-2^64, 2^64-1]"`
 - Throws [type_error.316](../../home/exceptions.md#jsonexceptiontype_error316) if a string or object key in `j` is
   not valid UTF-8 and `error_handler` is `strict` (the default only if
   [`JSON_STRICT_BINARY_UTF8`](../macros/json_strict_binary_utf8.md) is enabled)
@@ -90,3 +93,5 @@ Linear in the size of the JSON value `j`.
   [`JSON_STRICT_BINARY_UTF8`](../macros/json_strict_binary_utf8.md) is enabled) throws `type_error.316`.
 - Throws `type_error.321` for a discarded value since version 3.13.0; previously, a discarded value nested in an
   array or object was silently skipped, producing invalid CBOR.
+- Throws `out_of_range.407` for integers that do not fit 64 bits since version 3.13.0; previously, integers of a
+  number type wider than 64 bits were silently truncated.

docs/mkdocs/docs/api/basic_json/to_msgpack.md

@@ -46,6 +46,9 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
 
 ## Exceptions
 
+- Throws [`out_of_range.407`](../../home/exceptions.md#jsonexceptionout_of_range407) if `j` contains an integer
+  outside [-2^63, 2^64-1], which is only possible with a number type wider than 64 bits; example:
+  `"integer number 18446744073709551616 cannot be represented by MessagePack as it does not fit [-2^63, 2^64-1]"`
 - Throws [`out_of_range.412`](../../home/exceptions.md#jsonexceptionout_of_range412) if the length of a string, binary
   value, array, or object exceeds 4294967295, the maximum MessagePack can store; example:
   `"MessagePack length 4294967296 exceeds maximum of 4294967295"`
@@ -112,3 +115,5 @@ Linear in the size of the JSON value `j`.
   `number_unsigned_t`.
 - Throws `type_error.321` for a discarded value since version 3.13.0; previously, a discarded value nested in an
   array or object was silently skipped, producing invalid MessagePack.
+- Throws `out_of_range.407` for integers that do not fit 64 bits since version 3.13.0; previously, integers of a
+  number type wider than 64 bits were silently truncated.

docs/mkdocs/docs/features/types/index.md

@@ -120,7 +120,7 @@ requirements are collected in [Template Parameter Requirements](template_paramet
 
 ### Default type
 
-With the default values for *ObjectType* (`std::map`), *StringType* (`std::string`), and *AllocatorType* (`std::allocator`), the default value for `object_t` is:
+With the default values for *ObjectType* (`std::map`), *StringType* (`std::string`), and *AllocatorType* (`std::allocator`), the default type for `object_t` is:
 
 ```cpp
 std::map<
@@ -177,7 +177,7 @@ json j = m;
 
 ### Default type
 
-With the default values for *ArrayType* (`std::vector`) and *AllocatorType* (`std::allocator`), the default value for `array_t` is:
+With the default values for *ArrayType* (`std::vector`) and *AllocatorType* (`std::allocator`), the default type for `array_t` is:
 
 ```cpp
 std::vector<
@@ -209,7 +209,7 @@ Unicode values are split by the JSON class into byte-sized characters during des
 
 ### Default type
 
-With the default values for *StringType* (`std::string`), the default value for `string_t` is `#!cpp std::string`.
+With the default values for *StringType* (`std::string`), the default type for `string_t` is `#!cpp std::string`.
 
 ### Encoding
 
@@ -234,7 +234,7 @@ String values are stored as pointers in a `basic_json` type. That is, for any ac
 
 ### Default type
 
-With the default values for *BooleanType* (`#!cpp bool`), the default value for `boolean_t` is `#!cpp bool`.
+With the default values for *BooleanType* (`#!cpp bool`), the default type for `boolean_t` is `#!cpp bool`.
 
 ### Storage
 
@@ -252,9 +252,9 @@ This description includes both integer and floating-point numbers. However, C++
 
 ### Default types
 
-With the default values for *NumberIntegerType* (`std::int64_t`), the default value for `number_integer_t` is `std::int64_t`.
-With the default values for *NumberUnsignedType* (`std::uint64_t`), the default value for `number_unsigned_t` is `std::uint64_t`.
-With the default values for *NumberFloatType* (`#!cpp double`), the default value for `number_float_t` is `#!cpp double`.
+With the default values for *NumberIntegerType* (`std::int64_t`), the default type for `number_integer_t` is `std::int64_t`.
+With the default values for *NumberUnsignedType* (`std::uint64_t`), the default type for `number_unsigned_t` is `std::uint64_t`.
+With the default values for *NumberFloatType* (`#!cpp double`), the default type for `number_float_t` is `#!cpp double`.
 
 ### Default behavior
 
@@ -281,7 +281,7 @@ As this range is a subrange of the exactly supported range [`INT64_MIN`, `INT64_
 
 > This specification allows implementations to set limits on the range and precision of numbers accepted. Since software that implements IEEE 754-2008 binary64 (double precision) numbers is generally available and widely used, good interoperability can be achieved by implementations that expect no more precision or range than these provide, in the sense that implementations will approximate JSON numbers within the expected precision.
 
-This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note that numbers smaller than `#!c -1.79769313486232e+308` or greater than `#!c 1.79769313486232e+308` are rejected during parsing with [`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406). Non-finite values (NaN and infinity) can only be stored by assigning them directly and are serialized to `#!json null`.
+This implementation does exactly follow this approach, as it uses double precision floating-point numbers by default (see *NumberFloatType* above). Note that with the default `#!cpp double`, numbers smaller than `#!c -1.79769313486232e+308` or greater than `#!c 1.79769313486232e+308` are rejected during parsing with [`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406). Non-finite values (NaN and infinity) can only be stored by assigning them directly and are serialized to `#!json null`.
 
 ### Storage
 

docs/mkdocs/docs/features/types/number_handling.md

@@ -345,11 +345,8 @@ The number types can be changed with template parameters.
       in case of overflow.
     - The type for unsigned integers must be convertible from `#!c unsigned long long`.  The type for floating-point
       numbers is used in case of overflow.
-    - The type for unsigned integers can also be the same signed type as the type for signed integers (e.g.,
-      `#!c std::int64_t` for both). Then every integer is stored as a signed integer, and
-      [`is_number_unsigned()`](../../api/basic_json/is_number_unsigned.md) is always `#!c false`, see
-      [Template Parameter Requirements](template_parameters.md#same-type-for-both).
-    - The type for floating-point numbers must be distinct from the integer types.
+    - The types for signed and unsigned integers must be distinct, see
+      [#2573](https://github.com/nlohmann/json/issues/2573).
     - Only `#!c double`, `#!c float`, and `#!c long double` are supported for floating-point numbers.
 
 !!! example

docs/mkdocs/docs/features/types/template_parameters.md

@@ -40,19 +40,19 @@ Requirements are split into two groups:
 
 ## Overview
 
-| Template parameter                                                | Default                           | Notable substitutes                                                                              |
-|-------------------------------------------------------------------|-----------------------------------|--------------------------------------------------------------------------------------------------|
-| [`ObjectType`](#objecttype)                                       | `std::map`                        | [`nlohmann::ordered_map`](../../api/ordered_map.md), Abseil hash maps                            |
-| [`ArrayType`](#arraytype)                                         | `std::vector`                     | `#!cpp std::deque`                                                                               |
-| [`StringType`](#stringtype)                                       | `std::string`                     | `std::string`-like types over `char`                                                             |
-| [`BooleanType`](#booleantype)                                     | `bool`                            | none worth using                                                                                 |
-| [`NumberIntegerType`](#numberintegertype-and-numberunsignedtype)  | `std::int64_t`                    | any signed integer type                                                                          |
-| [`NumberUnsignedType`](#numberintegertype-and-numberunsignedtype) | `std::uint64_t`                   | any unsigned integer type at least as wide as `NumberIntegerType`, or `NumberIntegerType` itself |
-| [`NumberFloatType`](#numberfloattype)                             | `double`                          | `float` (`long double`: no binary formats)                                                       |
-| [`AllocatorType`](#allocatortype)                                 | `std::allocator`                  | stateless allocators                                                                             |
-| [`JSONSerializer`](#jsonserializer)                               | `adl_serializer`                  | serializers with the same interface                                                              |
-| [`BinaryType`](#binarytype)                                       | `#!cpp std::vector<std::uint8_t>` | `#!cpp std::vector<char>`                                                                        |
-| [`CustomBaseClass`](#custombaseclass)                             | `void`                            | any default-constructible class                                                                  |
+| Template parameter                                                | Default                           | Notable substitutes                                                   |
+|-------------------------------------------------------------------|-----------------------------------|-----------------------------------------------------------------------|
+| [`ObjectType`](#objecttype)                                       | `std::map`                        | [`nlohmann::ordered_map`](../../api/ordered_map.md), Abseil hash maps |
+| [`ArrayType`](#arraytype)                                         | `std::vector`                     | `#!cpp std::deque`                                                    |
+| [`StringType`](#stringtype)                                       | `std::string`                     | `std::string`-like types over `char`                                  |
+| [`BooleanType`](#booleantype)                                     | `bool`                            | none worth using                                                      |
+| [`NumberIntegerType`](#numberintegertype-and-numberunsignedtype)  | `std::int64_t`                    | any signed integer type                                               |
+| [`NumberUnsignedType`](#numberintegertype-and-numberunsignedtype) | `std::uint64_t`                   | any unsigned integer type at least as wide as `NumberIntegerType`     |
+| [`NumberFloatType`](#numberfloattype)                             | `double`                          | `float` (`long double`: no binary formats)                            |
+| [`AllocatorType`](#allocatortype)                                 | `std::allocator`                  | stateless allocators                                                  |
+| [`JSONSerializer`](#jsonserializer)                               | `adl_serializer`                  | serializers with the same interface                                   |
+| [`BinaryType`](#binarytype)                                       | `#!cpp std::vector<std::uint8_t>` | `#!cpp std::vector<char>`                                             |
+| [`CustomBaseClass`](#custombaseclass)                             | `void`                            | any default-constructible class                                       |
 
 !!! warning "Third-party containers and incomplete types"
 
@@ -504,14 +504,13 @@ Both types are stored **directly** inside `basic_json`'s union.
 ### Always required
 
 - `#!cpp std::is_integral` must be satisfied: `NumberIntegerType` must be a **signed** integer type,
-  `NumberUnsignedType` an **unsigned** integer type or the same type as `NumberIntegerType` (see
-  [below](#same-type-for-both)). Class types are not supported -- among others, the constructors taking integer values
-  are constrained on `#!cpp std::is_integral`.
+  `NumberUnsignedType` an **unsigned** integer type. Class types are not supported -- among others, the constructors
+  taking integer values are constrained on `#!cpp std::is_integral`.
 - Trivially default-constructible, trivially copyable, and trivially destructible (union member).
 - `#!cpp std::numeric_limits` must be specialized for both types.
-- An unsigned `NumberUnsignedType` must be able to represent the absolute value of every `NumberIntegerType` value;
-  serialization of negative numbers converts the value to `NumberUnsignedType`. A `#!cpp static_assert` requires it to
-  be at least as wide as `NumberIntegerType`, which is what that amounts to for the standard integer types.
+- `NumberUnsignedType` must be able to represent the absolute value of every `NumberIntegerType` value; serialization
+  of negative numbers converts the value to `NumberUnsignedType`. A `#!cpp static_assert` requires it to be at least as
+  wide as `NumberIntegerType`, which is what that amounts to for the standard integer types.
 - Both types must fit into the internal 64-character number buffer used by
   [`dump`](../../api/basic_json/dump.md), which is the case for all standard integer types.
 - [`std::hash<basic_json>`](../../api/basic_json/std_hash.md) additionally requires `#!cpp std::hash` specializations.
@@ -523,23 +522,6 @@ is stored as [`number_float_t`](../../api/basic_json/number_float_t.md) instead.
 therefore silently changes parse results rather than raising an error. See
 [Number Handling](number_handling.md) for details.
 
-#### Same type for both
-
-`NumberUnsignedType` may be the same type as `NumberIntegerType`, e.g.
-`#!cpp nlohmann::json::with_integers_t<std::int64_t, std::int64_t>` (see
-[`with_integers_t`](../../api/basic_json/with_t.md)), for code that only wants to handle one integer type. Such a `basic_json` stores every integer as
-[`number_integer_t`](../../api/basic_json/number_integer_t.md):
-
-- [`is_number_unsigned()`](../../api/basic_json/is_number_unsigned.md) is always `#!cpp false`, and
-  [`type()`](../../api/basic_json/type.md) never returns `value_t::number_unsigned`. Constructing a value from
-  `value_t::number_unsigned` gives a `value_t::number_integer` value.
-- Values of unsigned C++ types (e.g., `#!cpp 5u`) are converted to `NumberIntegerType`, so values above its maximum
-  wrap around, as values outside the range of a narrower `NumberIntegerType` already do.
-- The parsers store a non-negative integer above the maximum of `NumberIntegerType` (e.g., `18446744073709551615` for
-  `#!cpp std::int64_t`) as [`number_float_t`](../../api/basic_json/number_float_t.md), like any other integer that does
-  not fit.
-- Converting from a `basic_json` with distinct types turns its unsigned values into `number_integer_t` values.
-
 ### Compatible types
 
 | Type pair                                                                                    | Support                                                                                                                                                                                          |
@@ -547,9 +529,8 @@ therefore silently changes parse results rather than raising an error. See
 | `#!cpp std::int64_t` / `#!cpp std::uint64_t` (default)                                       | full                                                                                                                                                                                             |
 | `#!cpp std::int32_t` / `#!cpp std::uint32_t`, `#!cpp long long` / `#!cpp unsigned long long` | full; narrower types change which literals the parser can represent                                                                                                                              |
 | any other pair of standard signed/unsigned integer types                                     | full                                                                                                                                                                                             |
-| the same signed integer type for both, e.g. `#!cpp std::int64_t` / `#!cpp std::int64_t`      | full; every integer is stored as `number_integer_t`, see [above](#same-type-for-both)                                                                                                            |
 | class types, enumerations                                                                    | not usable; `#!cpp std::is_integral` must hold                                                                                                                                                   |
-| `#!cpp bool`, `number_float_t`, or the type of another member of the union                  | not usable; `#!cpp std::is_integral<bool>` is in fact `#!cpp true`, but the `get_impl_ptr` overloads for `boolean_t`, `number_integer_t`, `number_unsigned_t` and `number_float_t` would collide |
+| `#!cpp bool`, or a type already used for another member of the union                         | not usable; `#!cpp std::is_integral<bool>` is in fact `#!cpp true`, but the `get_impl_ptr` overloads for `boolean_t`, `number_integer_t`, `number_unsigned_t` and `number_float_t` would collide |
 
 ## `NumberFloatType`
 

docs/mkdocs/docs/home/exceptions.md

@@ -916,9 +916,19 @@ double-precision number when `number_float_t` is `#!cpp float`.
 
 ### json.exception.out_of_range.407
 
-An unsigned integer number greater than 9223372036854775807 cannot be represented in the binary format. This exception
-is only thrown by [`to_bon8`](../api/basic_json/to_bon8.md), as [BON8](../features/binary_formats/bon8.md) has no
-unsigned 64-bit integer type.
+An integer number cannot be represented by the binary format it is serialized to:
+
+- [BON8](../features/binary_formats/bon8.md) only stores integers that fit into int64, so
+  [`to_bon8`](../api/basic_json/to_bon8.md) throws for unsigned integers greater than 9223372036854775807.
+- [CBOR](../features/binary_formats/cbor.md), [MessagePack](../features/binary_formats/messagepack.md), and
+  [BSON](../features/binary_formats/bson.md) store integers in at most 64 bits. With the default number types, every
+  integer fits, but a [`number_integer_t`](../api/basic_json/number_integer_t.md) or
+  [`number_unsigned_t`](../api/basic_json/number_unsigned_t.md) wider than 64 bits (e.g., `__int128`) can hold values
+  outside the range of the format: [-2^64, 2^64-1] for CBOR, [-2^63, 2^64-1] for MessagePack, and the range of int64
+  (signed integers) or uint64 (unsigned integers) for BSON.
+
+[UBJSON](../features/binary_formats/ubjson.md) and [BJData](../features/binary_formats/bjdata.md) never throw this
+exception, because they serialize integers beyond 64 bits as high-precision numbers.
 
 !!! note "Former occurrences"
 
@@ -927,11 +937,17 @@ unsigned 64-bit integer type.
     - Since version 3.9.0, integer numbers beyond int64 are serialized as high-precision UBJSON numbers.
     - Since version 3.12.0, integer numbers beyond int64 are serialized as uint64 BSON numbers.
 
-!!! failure "Example message"
+    Before version 3.13.0, CBOR, MessagePack, and BSON silently truncated integers wider than 64 bits, and BJData
+    truncated unsigned integers wider than 64 bits.
+
+!!! failure "Example messages"
 
     ```
     integer number 18446744073709551615 cannot be represented by BON8 as it does not fit int64
     ```
+    ```
+    integer number 1267650600228229401496703205376 cannot be represented by CBOR as it does not fit [-2^64, 2^64-1]
+    ```
 
 ### json.exception.out_of_range.408
 

include/nlohmann/detail/conversions/from_json.hpp

@@ -80,11 +80,7 @@ void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val)
     {
         case value_t::number_unsigned:
         {
-            // never null: a basic_json whose number_unsigned_t is number_integer_t
-            // stores no number_unsigned values (#2573)
-            const auto* ptr = j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>();
-            JSON_ASSERT(ptr != nullptr);
-            val = static_cast<ArithmeticType>(*ptr);
+            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
             break;
         }
         case value_t::number_integer:
@@ -154,7 +150,7 @@ inline void from_json(const BasicJsonType& j, typename BasicJsonType::number_flo
 }
 
 template<typename BasicJsonType>
-inline void from_json(const BasicJsonType& j, number_unsigned_overload_t<BasicJsonType>& val)
+inline void from_json(const BasicJsonType& j, typename BasicJsonType::number_unsigned_t& val)
 {
     get_arithmetic_value(j, val);
 }
@@ -410,11 +406,7 @@ inline void from_json(const BasicJsonType& j, ArithmeticType& val)
     {
         case value_t::number_unsigned:
         {
-            // never null: a basic_json whose number_unsigned_t is number_integer_t
-            // stores no number_unsigned values (#2573)
-            const auto* ptr = j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>();
-            JSON_ASSERT(ptr != nullptr);
-            val = static_cast<ArithmeticType>(*ptr);
+            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
             break;
         }
         case value_t::number_integer:

include/nlohmann/detail/conversions/to_json.hpp

@@ -303,14 +303,14 @@ inline void to_json(BasicJsonType& j, FloatType val) noexcept
 }
 
 template<typename BasicJsonType, typename CompatibleNumberUnsignedType,
-         enable_if_t<is_compatible_integer_type<number_unsigned_overload_t<BasicJsonType>, CompatibleNumberUnsignedType>::value, int> = 0>
+         enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_unsigned_t, CompatibleNumberUnsignedType>::value, int> = 0>
 inline void to_json(BasicJsonType& j, CompatibleNumberUnsignedType val) noexcept
 {
     external_constructor<value_t::number_unsigned>::construct(j, static_cast<typename BasicJsonType::number_unsigned_t>(val));
 }
 
 template<typename BasicJsonType, typename CompatibleNumberIntegerType,
-         enable_if_t<is_compatible_number_integer_type<BasicJsonType, CompatibleNumberIntegerType>::value, int> = 0>
+         enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_integer_t, CompatibleNumberIntegerType>::value, int> = 0>
 inline void to_json(BasicJsonType& j, CompatibleNumberIntegerType val) noexcept
 {
     external_constructor<value_t::number_integer>::construct(j, static_cast<typename BasicJsonType::number_integer_t>(val));

include/nlohmann/detail/input/number_parse.hpp

@@ -19,7 +19,7 @@
 #include <cstring> // memcpy
 #include <limits> // numeric_limits
 #include <string> // string
-#include <type_traits> // conditional, integral_constant, is_signed, true_type, false_type
+#include <type_traits> // conditional, integral_constant, true_type, false_type
 #include <utility> // move
 
 #include <nlohmann/detail/bit_ops.hpp>
@@ -50,20 +50,6 @@ NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
 {
 
-// whether an integer of a signed type is negative; the overload for other types
-// avoids comparing an unsigned value with zero
-template<typename NumberType>
-constexpr bool is_negative_integer(NumberType x, std::true_type /*is_signed*/) noexcept
-{
-    return x < 0;
-}
-
-template<typename NumberType>
-constexpr bool is_negative_integer(NumberType /*unused*/, std::false_type /*is_signed*/) noexcept
-{
-    return false;
-}
-
 /*!
 @brief fast integer parser for an already-validated unsigned integer
 
@@ -97,10 +83,8 @@ bool parse_integer_unsigned(const char* first, const char* last, NumberUnsignedT
         x = (x * 10u) + digit;
     }
     value = static_cast<NumberUnsignedType>(x);
-    // reject values that do not round-trip into a narrower NumberUnsignedType,
-    // and values that wrap around to negative numbers if it is a signed type
-    // (number_unsigned_t may be the same type as number_integer_t, #2573)
-    return static_cast<std::uint64_t>(value) == x && !is_negative_integer(value, std::is_signed<NumberUnsignedType>());
+    // reject values that do not round-trip into a narrower NumberUnsignedType
+    return static_cast<std::uint64_t>(value) == x;
 }
 
 /*!

include/nlohmann/detail/meta/type_traits.hpp

@@ -683,22 +683,6 @@ struct is_compatible_integer_type
     : is_compatible_integer_type_impl<RealIntegerType,
       CompatibleNumberIntegerType> {};
 
-// whether to_json() stores an integer of type CompatibleNumberIntegerType as
-// number_integer
-template<typename BasicJsonType, typename CompatibleNumberIntegerType, typename = void>
-struct is_compatible_number_integer_type
-    : is_compatible_integer_type<typename BasicJsonType::number_integer_t, CompatibleNumberIntegerType> {};
-
-// if number_unsigned_t is the same type as number_integer_t, unsigned integers
-// are stored as number_integer as well (#2573)
-template<typename BasicJsonType, typename CompatibleNumberIntegerType>
-struct is_compatible_number_integer_type<BasicJsonType, CompatibleNumberIntegerType,
-           enable_if_t<conjunction<std::is_same<typename BasicJsonType::number_integer_t, typename BasicJsonType::number_unsigned_t>,
-           std::is_integral<CompatibleNumberIntegerType>,
-           std::is_unsigned<CompatibleNumberIntegerType>,
-           negation<std::is_same<bool, CompatibleNumberIntegerType>>>::value>>
-           : std::is_constructible<typename BasicJsonType::number_integer_t, CompatibleNumberIntegerType> {};
-
 template<typename BasicJsonType, typename CompatibleType, typename = void>
 struct is_compatible_type_impl: std::false_type {};
 
@@ -1036,25 +1020,6 @@ constexpr bool value_in_range_of(T val)
 template<bool Value>
 using bool_constant = std::integral_constant<bool, Value>;
 
-// Stands in for number_unsigned_t in overload sets if it is the same type as
-// number_integer_t, so that the unsigned overloads do not collide with the
-// integer ones. Never constructed. Such a basic_json stores every integer as
-// number_integer (#2573).
-struct same_as_number_integer_type {};
-
-// NumberUnsignedType, or same_as_number_integer_type if it is the same type as
-// NumberIntegerType; basic_json uses this one, as it cannot name its own member
-// types through an incomplete basic_json (MSVC reports a recursive alias, and
-// old GCC versions crash)
-template<typename NumberIntegerType, typename NumberUnsignedType>
-using number_unsigned_overload_type = typename std::conditional<std::is_same<NumberIntegerType, NumberUnsignedType>::value,
-      same_as_number_integer_type, NumberUnsignedType>::type;
-
-// number_unsigned_t of BasicJsonType, or same_as_number_integer_type if it is
-// the same type as number_integer_t
-template<typename BasicJsonType>
-using number_unsigned_overload_t = number_unsigned_overload_type<typename BasicJsonType::number_integer_t, typename BasicJsonType::number_unsigned_t>;
-
 ///////////////////////////////////////////////////////////////////////////////
 // is_c_string
 ///////////////////////////////////////////////////////////////////////////////

include/nlohmann/detail/output/binary_writer.hpp

@@ -207,6 +207,10 @@ class binary_writer
             {
                 if (j.m_data.m_value.number_integer >= 0)
                 {
+                    if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_integer)))
+                    {
+                        throw_integer_out_of_range(j, "CBOR", "[-2^64, 2^64-1]");
+                    }
                     // CBOR does not differentiate between positive signed
                     // integers and unsigned integers
                     write_cbor_head(0x00, static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
@@ -214,6 +218,10 @@ class binary_writer
                 else
                 {
                     // a negative integer n is encoded as -1 - n
+                    if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(-1 - j.m_data.m_value.number_integer)))
+                    {
+                        throw_integer_out_of_range(j, "CBOR", "[-2^64, 2^64-1]");
+                    }
                     write_cbor_head(0x20, static_cast<std::uint64_t>(-1 - j.m_data.m_value.number_integer));
                 }
                 break;
@@ -221,7 +229,11 @@ class binary_writer
 
             case value_t::number_unsigned:
             {
-                write_cbor_head(0x00, conditional_static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_unsigned)))
+                {
+                    throw_integer_out_of_range(j, "CBOR", "uint64");
+                }
+                write_cbor_head(0x00, static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
                 break;
             }
 
@@ -423,12 +435,20 @@ class binary_writer
             {
                 if (j.m_data.m_value.number_integer >= 0)
                 {
+                    if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_integer)))
+                    {
+                        throw_integer_out_of_range(j, "MessagePack", "[-2^63, 2^64-1]");
+                    }
                     // MessagePack does not differentiate between positive
                     // signed integers and unsigned integers.
                     write_msgpack_unsigned(static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
                 }
                 else
                 {
+                    if (JSON_HEDLEY_UNLIKELY(!integer_fits_min<std::int64_t>(j.m_data.m_value.number_integer)))
+                    {
+                        throw_integer_out_of_range(j, "MessagePack", "[-2^63, 2^64-1]");
+                    }
                     if (j.m_data.m_value.number_integer >= -32)
                     {
                         // negative fixnum
@@ -467,6 +487,10 @@ class binary_writer
 
             case value_t::number_unsigned:
             {
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_unsigned)))
+                {
+                    throw_integer_out_of_range(j, "MessagePack", "uint64");
+                }
                 write_msgpack_unsigned(static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
                 break;
             }
@@ -824,6 +848,133 @@ class binary_writer
         JSON_THROW(type_error::create(exception_id::discarded_value_used, concat("cannot serialize discarded value to ", format_name), &j));
     }
 
+    /*!
+    @brief whether integer @a n does not exceed the maximum of @a TargetType
+
+    The binary formats store integers in at most 64 bits, but number_integer_t
+    and number_unsigned_t may be wider (e.g., __int128). The range of the
+    integer is taken from std::numeric_limits, so a number type whose range
+    fits into @a TargetType is never checked: the function is then constant
+    true, and the default int64_t/uint64_t types pay nothing.
+    */
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_max(const NumberType n) noexcept
+    {
+        return integer_fits_max<TargetType>(n, std::integral_constant < bool,
+                                            (std::numeric_limits<NumberType>::digits > std::numeric_limits<TargetType>::digits) > ());
+    }
+
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_max(const NumberType /*unused*/, std::false_type /*may_exceed*/) noexcept
+    {
+        return true;
+    }
+
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_max(const NumberType n, std::true_type /*may_exceed*/) noexcept
+    {
+        // NumberType has more digits than TargetType, so it can hold its maximum
+        return n <= static_cast<NumberType>((std::numeric_limits<TargetType>::max)());
+    }
+
+    /*!
+    @brief whether integer @a n is not below the minimum of @a TargetType;
+           constant true if NumberType cannot hold such a value
+    */
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_min(const NumberType n) noexcept
+    {
+        return integer_fits_min<TargetType>(n, std::integral_constant < bool, std::numeric_limits<NumberType>::is_signed &&
+                                            (!std::numeric_limits<TargetType>::is_signed || std::numeric_limits<NumberType>::digits > std::numeric_limits<TargetType>::digits) > ());
+    }
+
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_min(const NumberType /*unused*/, std::false_type /*may_fall_below*/) noexcept
+    {
+        return true;
+    }
+
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_min(const NumberType n, std::true_type /*may_fall_below*/) noexcept
+    {
+        // NumberType is signed and either TargetType is unsigned (minimum 0)
+        // or NumberType has more digits, so it can hold the minimum
+        return n >= static_cast<NumberType>((std::numeric_limits<TargetType>::min)());
+    }
+
+    /*!
+    @brief whether integer @a n lies in the range of @a TargetType
+    */
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits(const NumberType n) noexcept
+    {
+        return integer_fits_min<TargetType>(n) && integer_fits_max<TargetType>(n);
+    }
+
+    /*!
+    @brief the decimal digits of the non-negative integer @a n
+    */
+    template<typename NumberType>
+    static std::string integer_to_string(NumberType n, std::false_type /*is_signed*/)
+    {
+        std::string result;
+        do
+        {
+            result.push_back(static_cast<char>('0' + (n % 10)));
+            n = static_cast<NumberType>(n / 10);
+        }
+        while (n != 0);
+        std::reverse(result.begin(), result.end());
+        return result;
+    }
+
+    /*!
+    @brief the decimal digits of the integer @a n, with a leading '-' if it
+           is negative
+    */
+    template<typename NumberType>
+    static std::string integer_to_string(NumberType n, std::true_type /*is_signed*/)
+    {
+        // the remainder of a negative n is not positive; each digit is
+        // negated on its own, because negating the minimum of NumberType
+        // as a whole would overflow
+        const bool negative = n < 0;
+        std::string result;
+        do
+        {
+            const auto remainder = n % 10;
+            result.push_back(static_cast<char>('0' + (remainder < 0 ? -remainder : remainder)));
+            n = static_cast<NumberType>(n / 10);
+        }
+        while (n != 0);
+        if (negative)
+        {
+            result.push_back('-');
+        }
+        std::reverse(result.begin(), result.end());
+        return result;
+    }
+
+    /*!
+    @brief throws because the integer @a j is too large for @a format_name
+    @throw out_of_range.407 always
+    */
+    JSON_HEDLEY_NO_RETURN static void throw_integer_out_of_range(const BasicJsonType& j, const char* format_name, const char* range)
+    {
+        // neither std::to_string(), which has no overload for integer types
+        // wider than 64 bits, nor dump(), which would also instantiate the
+        // serializer for objects and fail for key types it cannot write
+        using integer_limits = std::numeric_limits<typename BasicJsonType::number_integer_t>;
+        using unsigned_limits = std::numeric_limits<typename BasicJsonType::number_unsigned_t>;
+        const std::string number = j.is_number_unsigned()
+                                   ? integer_to_string(j.m_data.m_value.number_unsigned, std::integral_constant<bool, unsigned_limits::is_signed>())
+                                   : integer_to_string(j.m_data.m_value.number_integer, std::integral_constant<bool, integer_limits::is_signed>());
+        static_cast<void>(number); // unused when JSON_NOEXCEPTION is defined
+        static_cast<void>(format_name);
+        static_cast<void>(range);
+        JSON_THROW(out_of_range::create(exception_id::integer_too_large, concat("integer number ", number, " cannot be represented by ", format_name, " as it does not fit ", range), &j));
+    }
+
     void write_msgpack_array_prefix(const std::size_t N, const BasicJsonType& j)
     {
         const auto n = to_msgpack_length(N, j);
@@ -1580,6 +1731,8 @@ class binary_writer
             is neither an object nor an array
     @throw out_of_range.415 if @a j is binary with a subtype that does not fit
            into a byte, before anything is written
+    @throw out_of_range.407 if @a j is an integer that does not fit the 64 bits
+           of a BSON integer, before anything is written
     @throw type_error.316 if @a j is a string that is not valid UTF-8, before
            anything is written
     @throw type_error.321 if @a j is discarded
@@ -1598,10 +1751,18 @@ class binary_writer
                 return 8ul;
 
             case value_t::number_integer:
-                return calc_bson_integer_size(j.m_data.m_value.number_integer);
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits<std::int64_t>(j.m_data.m_value.number_integer)))
+                {
+                    throw_integer_out_of_range(j, "BSON", "int64");
+                }
+                return calc_bson_integer_size(static_cast<std::int64_t>(j.m_data.m_value.number_integer));
 
             case value_t::number_unsigned:
-                return calc_bson_unsigned_size(conditional_static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_unsigned)))
+                {
+                    throw_integer_out_of_range(j, "BSON", "uint64");
+                }
+                return calc_bson_unsigned_size(static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
 
             case value_t::string:
                 return calc_bson_string_size(*j.m_data.m_value.string, j);
@@ -1639,11 +1800,12 @@ class binary_writer
             case value_t::number_float:
                 return write_bson_double(name, j.m_data.m_value.number_float);
 
+            // calc_bson_value_size() checked that integers fit 64 bits
             case value_t::number_integer:
-                return write_bson_integer(name, j.m_data.m_value.number_integer);
+                return write_bson_integer(name, static_cast<std::int64_t>(j.m_data.m_value.number_integer));
 
             case value_t::number_unsigned:
-                return write_bson_unsigned(name, conditional_static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
+                return write_bson_unsigned(name, static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
 
             case value_t::string:
                 return write_bson_string(name, *j.m_data.m_value.string);
@@ -2147,7 +2309,7 @@ class binary_writer
         {
             return 'L';
         }
-        if (use_bjdata && std::is_unsigned<NumberType>::value)
+        if (use_bjdata && std::is_unsigned<NumberType>::value && integer_fits_max<std::uint64_t>(n))
         {
             return 'M';
         }
@@ -2272,14 +2434,16 @@ class binary_writer
     @brief checks whether a JSON number fits into @a TargetType
     @param[in] el a JSON number of either the signed or unsigned integer kind
     @return whether @a el's value can be represented by @a TargetType without
-            wrapping, regardless of which of the two kinds it is stored as
+            wrapping, regardless of which of the two kinds it is stored as;
+            false for a value that does not even fit the 64-bit type it is
+            read as (possible for number types wider than 64 bits)
     */
     template<typename TargetType>
     static bool bjdata_ndarray_value_in_range(const BasicJsonType& el)
     {
         return el.is_number_unsigned()
-               ? value_in_range_of<TargetType>(el.template get<std::uint64_t>())
-               : value_in_range_of<TargetType>(el.template get<std::int64_t>());
+               ? integer_fits_max<std::uint64_t>(el.m_data.m_value.number_unsigned) && value_in_range_of<TargetType>(el.template get<std::uint64_t>())
+               : integer_fits<std::int64_t>(el.m_data.m_value.number_integer) && value_in_range_of<TargetType>(el.template get<std::int64_t>());
     }
 
     /*!
@@ -2511,10 +2675,11 @@ class binary_writer
         for (const auto& el : dims)
         {
             // a dimension is read as an unsigned value below, so anything that
-            // is not a non-negative integer is rejected: a non-integer entry
-            // would pun unrelated bytes as the dimension, and a negative one
-            // would wrap into a nonsensical length
-            if (!el.is_number_integer() || (!el.is_number_unsigned() && el.template get<std::int64_t>() < 0))
+            // is not a non-negative integer in the range of std::uint64_t is
+            // rejected: a non-integer entry would pun unrelated bytes as the
+            // dimension, and a negative or wider one would wrap into a
+            // nonsensical length
+            if (!el.is_number_integer() || !bjdata_ndarray_value_in_range<std::uint64_t>(el))
             {
                 return true;
             }
@@ -2646,9 +2811,9 @@ class binary_writer
 
             case value_t::number_unsigned:
             {
-                if (j.m_data.m_value.number_unsigned > static_cast<typename BasicJsonType::number_unsigned_t>((std::numeric_limits<std::int64_t>::max)()))
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::int64_t>(j.m_data.m_value.number_unsigned)))
                 {
-                    JSON_THROW(out_of_range::create(exception_id::integer_too_large, concat("integer number ", std::to_string(j.m_data.m_value.number_unsigned), " cannot be represented by BON8 as it does not fit int64"), &j));
+                    throw_integer_out_of_range(j, "BON8", "int64");
                 }
                 write_bon8_integer(static_cast<std::int64_t>(j.m_data.m_value.number_unsigned));
                 string_open = false;
@@ -2657,6 +2822,10 @@ class binary_writer
 
             case value_t::number_integer:
             {
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits<std::int64_t>(j.m_data.m_value.number_integer)))
+                {
+                    throw_integer_out_of_range(j, "BON8", "int64");
+                }
                 write_bon8_integer(static_cast<std::int64_t>(j.m_data.m_value.number_integer));
                 string_open = false;
                 break;

include/nlohmann/detail/output/serializer.hpp

@@ -49,12 +49,6 @@ class serializer
     using number_float_t = typename BasicJsonType::number_float_t;
     using number_integer_t = typename BasicJsonType::number_integer_t;
     using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    /// type of the absolute value of an integer: number_unsigned_t, or its
-    /// unsigned counterpart if it is signed (it may be number_integer_t, #2573)
-    using number_magnitude_t = typename std::conditional <
-                               std::is_integral<number_unsigned_t>::value && std::is_signed<number_unsigned_t>::value,
-                               std::make_unsigned<number_unsigned_t>,
-                               std::enable_if<true, number_unsigned_t >>::type::type;
     using binary_char_t = typename BasicJsonType::binary_t::value_type;
 
   public:
@@ -1233,7 +1227,7 @@ class serializer
     @param[in] x  unsigned integer number to count its digits
     @return    number of decimal digits
     */
-    unsigned int count_digits(number_magnitude_t x) noexcept
+    unsigned int count_digits(number_unsigned_t x) noexcept
     {
         unsigned int n_digits = 1;
         for (;;)
@@ -1416,7 +1410,7 @@ class serializer
         }
         auto* buffer_ptr = write_buffer.data() + write_buffer_pos;
 
-        number_magnitude_t abs_value;
+        number_unsigned_t abs_value;
 
         // one byte for the minus sign
         unsigned int n_chars = 0;
@@ -1429,7 +1423,7 @@ class serializer
         }
         else
         {
-            abs_value = static_cast<number_magnitude_t>(x);
+            abs_value = static_cast<number_unsigned_t>(x);
         }
 
         // up to 16 digits: eight at a time (as the digits of floats), written
@@ -1597,6 +1591,17 @@ class serializer
         }
     }
 
+    /*
+     * Overload to make the compiler happy while it is instantiating
+     * dump_integer for number_unsigned_t.
+     * Must never be called.
+     */
+    number_unsigned_t remove_sign(number_unsigned_t x)
+    {
+        JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
+        return x; // LCOV_EXCL_LINE
+    }
+
     /*
      * Helper function for dump_integer
      *
@@ -1606,10 +1611,10 @@ class serializer
      * absolute values of INT_MIN and INT_MAX are usually not the same. See
      * #1708 for details.
      */
-    number_magnitude_t remove_sign(number_integer_t x) noexcept
+    number_unsigned_t remove_sign(number_integer_t x) noexcept
     {
         JSON_ASSERT(x < 0);
-        return static_cast<number_magnitude_t>(-(x + 1)) + 1;
+        return static_cast<number_unsigned_t>(-(x + 1)) + 1;
     }
 
   private:

include/nlohmann/detail/value_t.hpp

@@ -14,7 +14,6 @@
 #include <cstdint> // uint8_t
 #include <limits> // numeric_limits
 #include <string> // string
-#include <type_traits> // is_signed
 
 #include <nlohmann/detail/macro_scope.hpp>
 #if JSON_HAS_THREE_WAY_COMPARISON
@@ -147,13 +146,16 @@ FloatType compare_integer_with_float(const IntegerType i, const FloatType f) noe
 
     // values of IntegerType lie in [-bound, bound) when signed and in
     // [0, bound) when unsigned; digits excludes the sign bit, so bound is a
-    // power of two that the float represents exactly
-    const FloatType bound = std::ldexp(static_cast<FloatType>(1), std::numeric_limits<IntegerType>::digits);
+    // power of two that the float represents exactly; the signedness comes
+    // from numeric_limits as well, because std::is_signed is false for class
+    // types such as 128-bit or multiprecision integers
+    using limits = std::numeric_limits<IntegerType>;
+    const FloatType bound = std::ldexp(static_cast<FloatType>(1), limits::digits);
     if (f >= bound)
     {
         return ordered(-1);
     }
-    if (std::is_signed<IntegerType>::value ? (f < -bound) : (f < static_cast<FloatType>(0)))
+    if (limits::is_signed ? (f < -bound) : (f < static_cast<FloatType>(0)))
     {
         return ordered(1);
     }

include/nlohmann/json.hpp

@@ -500,22 +500,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                   "NumberUnsignedType must be at least as wide as NumberIntegerType, "
                   "because it has to hold the absolute value of every NumberIntegerType value");
 
-    // NumberUnsignedType may be the same type as NumberIntegerType (#2573), but
-    // a repeated NumberFloatType would give overloads that collide, so it gets
-    // a readable diagnostic instead.
-    static_assert(!std::is_same<NumberFloatType, NumberIntegerType>::value && !std::is_same<NumberFloatType, NumberUnsignedType>::value,
-                  "NumberFloatType must be a different type than NumberIntegerType and NumberUnsignedType");
-
   private:
 
-    /// the kind a value of kind @a t is stored as: if number_unsigned_t is the
-    /// same type as number_integer_t, every integer is stored as number_integer
-    /// (#2573); every other kind is stored as itself
-    static constexpr value_t stored_kind(const value_t t) noexcept
-    {
-        return (std::is_same<number_integer_t, number_unsigned_t>::value && t == value_t::number_unsigned) ? value_t::number_integer : t;
-    }
-
     /// helper for exception-safe object creation
     template<typename T, typename... Args>
     JSON_HEDLEY_RETURNS_NON_NULL
@@ -589,8 +575,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         json_value(boolean_t v) noexcept : boolean(v) {}
         /// constructor for numbers (integer)
         json_value(number_integer_t v) noexcept : number_integer(v) {}
-        /// constructor for numbers (unsigned); takes a placeholder if number_unsigned_t is number_integer_t
-        json_value(detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType> v) noexcept : number_unsigned(v) {}
+        /// constructor for numbers (unsigned)
+        json_value(number_unsigned_t v) noexcept : number_unsigned(v) {}
         /// constructor for numbers (floating-point)
         json_value(number_float_t v) noexcept : number_float(v) {}
         /// constructor for empty values of a given type
@@ -2195,7 +2181,7 @@ public:
     /// @brief create an empty value with a given type
     /// @sa https://json.nlohmann.me/api/basic_json/basic_json/
     basic_json(const value_t v)
-        : m_data(stored_kind(v))
+        : m_data(v)
     {
         assert_invariant();
     }
@@ -2276,7 +2262,7 @@ public:
         {
             convert_leaf(val);
         }
-        JSON_ASSERT(m_data.m_type == stored_kind(val.type()));
+        JSON_ASSERT(m_data.m_type == val.type());
 
         set_parents();
         assert_invariant();
@@ -2861,16 +2847,14 @@ public:
         return m_data.m_type == value_t::number_integer ? &m_data.m_value.number_integer : nullptr;
     }
 
-    /// get a pointer to the value (unsigned number); takes a placeholder if
-    /// number_unsigned_t is number_integer_t (the integer overload handles it then)
-    number_unsigned_t* get_impl_ptr(detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>* /*unused*/) noexcept
+    /// get a pointer to the value (unsigned number)
+    number_unsigned_t* get_impl_ptr(number_unsigned_t* /*unused*/) noexcept
     {
         return is_number_unsigned() ? &m_data.m_value.number_unsigned : nullptr;
     }
 
-    /// get a pointer to the value (unsigned number); takes a placeholder if
-    /// number_unsigned_t is number_integer_t (the integer overload handles it then)
-    constexpr const number_unsigned_t* get_impl_ptr(const detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>* /*unused*/) const noexcept
+    /// get a pointer to the value (unsigned number)
+    constexpr const number_unsigned_t* get_impl_ptr(const number_unsigned_t* /*unused*/) const noexcept
     {
         return is_number_unsigned() ? &m_data.m_value.number_unsigned : nullptr;
     }

single_include/nlohmann/json.hpp

@@ -289,7 +289,6 @@
 #include <cstdint> // uint8_t
 #include <limits> // numeric_limits
 #include <string> // string
-#include <type_traits> // is_signed
 
 // #include <nlohmann/detail/macro_scope.hpp>
 //     __ _____ _____ _____
@@ -3368,13 +3367,16 @@ FloatType compare_integer_with_float(const IntegerType i, const FloatType f) noe
 
     // values of IntegerType lie in [-bound, bound) when signed and in
     // [0, bound) when unsigned; digits excludes the sign bit, so bound is a
-    // power of two that the float represents exactly
-    const FloatType bound = std::ldexp(static_cast<FloatType>(1), std::numeric_limits<IntegerType>::digits);
+    // power of two that the float represents exactly; the signedness comes
+    // from numeric_limits as well, because std::is_signed is false for class
+    // types such as 128-bit or multiprecision integers
+    using limits = std::numeric_limits<IntegerType>;
+    const FloatType bound = std::ldexp(static_cast<FloatType>(1), limits::digits);
     if (f >= bound)
     {
         return ordered(-1);
     }
-    if (std::is_signed<IntegerType>::value ? (f < -bound) : (f < static_cast<FloatType>(0)))
+    if (limits::is_signed ? (f < -bound) : (f < static_cast<FloatType>(0)))
     {
         return ordered(1);
     }
@@ -4687,22 +4689,6 @@ struct is_compatible_integer_type
     : is_compatible_integer_type_impl<RealIntegerType,
       CompatibleNumberIntegerType> {};
 
-// whether to_json() stores an integer of type CompatibleNumberIntegerType as
-// number_integer
-template<typename BasicJsonType, typename CompatibleNumberIntegerType, typename = void>
-struct is_compatible_number_integer_type
-    : is_compatible_integer_type<typename BasicJsonType::number_integer_t, CompatibleNumberIntegerType> {};
-
-// if number_unsigned_t is the same type as number_integer_t, unsigned integers
-// are stored as number_integer as well (#2573)
-template<typename BasicJsonType, typename CompatibleNumberIntegerType>
-struct is_compatible_number_integer_type<BasicJsonType, CompatibleNumberIntegerType,
-           enable_if_t<conjunction<std::is_same<typename BasicJsonType::number_integer_t, typename BasicJsonType::number_unsigned_t>,
-           std::is_integral<CompatibleNumberIntegerType>,
-           std::is_unsigned<CompatibleNumberIntegerType>,
-           negation<std::is_same<bool, CompatibleNumberIntegerType>>>::value>>
-           : std::is_constructible<typename BasicJsonType::number_integer_t, CompatibleNumberIntegerType> {};
-
 template<typename BasicJsonType, typename CompatibleType, typename = void>
 struct is_compatible_type_impl: std::false_type {};
 
@@ -5040,25 +5026,6 @@ constexpr bool value_in_range_of(T val)
 template<bool Value>
 using bool_constant = std::integral_constant<bool, Value>;
 
-// Stands in for number_unsigned_t in overload sets if it is the same type as
-// number_integer_t, so that the unsigned overloads do not collide with the
-// integer ones. Never constructed. Such a basic_json stores every integer as
-// number_integer (#2573).
-struct same_as_number_integer_type {};
-
-// NumberUnsignedType, or same_as_number_integer_type if it is the same type as
-// NumberIntegerType; basic_json uses this one, as it cannot name its own member
-// types through an incomplete basic_json (MSVC reports a recursive alias, and
-// old GCC versions crash)
-template<typename NumberIntegerType, typename NumberUnsignedType>
-using number_unsigned_overload_type = typename std::conditional<std::is_same<NumberIntegerType, NumberUnsignedType>::value,
-      same_as_number_integer_type, NumberUnsignedType>::type;
-
-// number_unsigned_t of BasicJsonType, or same_as_number_integer_type if it is
-// the same type as number_integer_t
-template<typename BasicJsonType>
-using number_unsigned_overload_t = number_unsigned_overload_type<typename BasicJsonType::number_integer_t, typename BasicJsonType::number_unsigned_t>;
-
 ///////////////////////////////////////////////////////////////////////////////
 // is_c_string
 ///////////////////////////////////////////////////////////////////////////////
@@ -5811,11 +5778,7 @@ void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val)
     {
         case value_t::number_unsigned:
         {
-            // never null: a basic_json whose number_unsigned_t is number_integer_t
-            // stores no number_unsigned values (#2573)
-            const auto* ptr = j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>();
-            JSON_ASSERT(ptr != nullptr);
-            val = static_cast<ArithmeticType>(*ptr);
+            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
             break;
         }
         case value_t::number_integer:
@@ -5885,7 +5848,7 @@ inline void from_json(const BasicJsonType& j, typename BasicJsonType::number_flo
 }
 
 template<typename BasicJsonType>
-inline void from_json(const BasicJsonType& j, number_unsigned_overload_t<BasicJsonType>& val)
+inline void from_json(const BasicJsonType& j, typename BasicJsonType::number_unsigned_t& val)
 {
     get_arithmetic_value(j, val);
 }
@@ -6141,11 +6104,7 @@ inline void from_json(const BasicJsonType& j, ArithmeticType& val)
     {
         case value_t::number_unsigned:
         {
-            // never null: a basic_json whose number_unsigned_t is number_integer_t
-            // stores no number_unsigned values (#2573)
-            const auto* ptr = j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>();
-            JSON_ASSERT(ptr != nullptr);
-            val = static_cast<ArithmeticType>(*ptr);
+            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
             break;
         }
         case value_t::number_integer:
@@ -7293,14 +7252,14 @@ inline void to_json(BasicJsonType& j, FloatType val) noexcept
 }
 
 template<typename BasicJsonType, typename CompatibleNumberUnsignedType,
-         enable_if_t<is_compatible_integer_type<number_unsigned_overload_t<BasicJsonType>, CompatibleNumberUnsignedType>::value, int> = 0>
+         enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_unsigned_t, CompatibleNumberUnsignedType>::value, int> = 0>
 inline void to_json(BasicJsonType& j, CompatibleNumberUnsignedType val) noexcept
 {
     external_constructor<value_t::number_unsigned>::construct(j, static_cast<typename BasicJsonType::number_unsigned_t>(val));
 }
 
 template<typename BasicJsonType, typename CompatibleNumberIntegerType,
-         enable_if_t<is_compatible_number_integer_type<BasicJsonType, CompatibleNumberIntegerType>::value, int> = 0>
+         enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_integer_t, CompatibleNumberIntegerType>::value, int> = 0>
 inline void to_json(BasicJsonType& j, CompatibleNumberIntegerType val) noexcept
 {
     external_constructor<value_t::number_integer>::construct(j, static_cast<typename BasicJsonType::number_integer_t>(val));
@@ -9130,7 +9089,7 @@ NLOHMANN_JSON_NAMESPACE_END
 #include <cstring> // memcpy
 #include <limits> // numeric_limits
 #include <string> // string
-#include <type_traits> // conditional, integral_constant, is_signed, true_type, false_type
+#include <type_traits> // conditional, integral_constant, true_type, false_type
 #include <utility> // move
 
 // #include <nlohmann/detail/bit_ops.hpp>
@@ -9540,20 +9499,6 @@ NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
 {
 
-// whether an integer of a signed type is negative; the overload for other types
-// avoids comparing an unsigned value with zero
-template<typename NumberType>
-constexpr bool is_negative_integer(NumberType x, std::true_type /*is_signed*/) noexcept
-{
-    return x < 0;
-}
-
-template<typename NumberType>
-constexpr bool is_negative_integer(NumberType /*unused*/, std::false_type /*is_signed*/) noexcept
-{
-    return false;
-}
-
 /*!
 @brief fast integer parser for an already-validated unsigned integer
 
@@ -9587,10 +9532,8 @@ bool parse_integer_unsigned(const char* first, const char* last, NumberUnsignedT
         x = (x * 10u) + digit;
     }
     value = static_cast<NumberUnsignedType>(x);
-    // reject values that do not round-trip into a narrower NumberUnsignedType,
-    // and values that wrap around to negative numbers if it is a signed type
-    // (number_unsigned_t may be the same type as number_integer_t, #2573)
-    return static_cast<std::uint64_t>(value) == x && !is_negative_integer(value, std::is_signed<NumberUnsignedType>());
+    // reject values that do not round-trip into a narrower NumberUnsignedType
+    return static_cast<std::uint64_t>(value) == x;
 }
 
 /*!
@@ -22603,6 +22546,10 @@ class binary_writer
             {
                 if (j.m_data.m_value.number_integer >= 0)
                 {
+                    if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_integer)))
+                    {
+                        throw_integer_out_of_range(j, "CBOR", "[-2^64, 2^64-1]");
+                    }
                     // CBOR does not differentiate between positive signed
                     // integers and unsigned integers
                     write_cbor_head(0x00, static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
@@ -22610,6 +22557,10 @@ class binary_writer
                 else
                 {
                     // a negative integer n is encoded as -1 - n
+                    if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(-1 - j.m_data.m_value.number_integer)))
+                    {
+                        throw_integer_out_of_range(j, "CBOR", "[-2^64, 2^64-1]");
+                    }
                     write_cbor_head(0x20, static_cast<std::uint64_t>(-1 - j.m_data.m_value.number_integer));
                 }
                 break;
@@ -22617,7 +22568,11 @@ class binary_writer
 
             case value_t::number_unsigned:
             {
-                write_cbor_head(0x00, conditional_static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_unsigned)))
+                {
+                    throw_integer_out_of_range(j, "CBOR", "uint64");
+                }
+                write_cbor_head(0x00, static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
                 break;
             }
 
@@ -22819,12 +22774,20 @@ class binary_writer
             {
                 if (j.m_data.m_value.number_integer >= 0)
                 {
+                    if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_integer)))
+                    {
+                        throw_integer_out_of_range(j, "MessagePack", "[-2^63, 2^64-1]");
+                    }
                     // MessagePack does not differentiate between positive
                     // signed integers and unsigned integers.
                     write_msgpack_unsigned(static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
                 }
                 else
                 {
+                    if (JSON_HEDLEY_UNLIKELY(!integer_fits_min<std::int64_t>(j.m_data.m_value.number_integer)))
+                    {
+                        throw_integer_out_of_range(j, "MessagePack", "[-2^63, 2^64-1]");
+                    }
                     if (j.m_data.m_value.number_integer >= -32)
                     {
                         // negative fixnum
@@ -22863,6 +22826,10 @@ class binary_writer
 
             case value_t::number_unsigned:
             {
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_unsigned)))
+                {
+                    throw_integer_out_of_range(j, "MessagePack", "uint64");
+                }
                 write_msgpack_unsigned(static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
                 break;
             }
@@ -23220,6 +23187,133 @@ class binary_writer
         JSON_THROW(type_error::create(exception_id::discarded_value_used, concat("cannot serialize discarded value to ", format_name), &j));
     }
 
+    /*!
+    @brief whether integer @a n does not exceed the maximum of @a TargetType
+
+    The binary formats store integers in at most 64 bits, but number_integer_t
+    and number_unsigned_t may be wider (e.g., __int128). The range of the
+    integer is taken from std::numeric_limits, so a number type whose range
+    fits into @a TargetType is never checked: the function is then constant
+    true, and the default int64_t/uint64_t types pay nothing.
+    */
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_max(const NumberType n) noexcept
+    {
+        return integer_fits_max<TargetType>(n, std::integral_constant < bool,
+                                            (std::numeric_limits<NumberType>::digits > std::numeric_limits<TargetType>::digits) > ());
+    }
+
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_max(const NumberType /*unused*/, std::false_type /*may_exceed*/) noexcept
+    {
+        return true;
+    }
+
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_max(const NumberType n, std::true_type /*may_exceed*/) noexcept
+    {
+        // NumberType has more digits than TargetType, so it can hold its maximum
+        return n <= static_cast<NumberType>((std::numeric_limits<TargetType>::max)());
+    }
+
+    /*!
+    @brief whether integer @a n is not below the minimum of @a TargetType;
+           constant true if NumberType cannot hold such a value
+    */
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_min(const NumberType n) noexcept
+    {
+        return integer_fits_min<TargetType>(n, std::integral_constant < bool, std::numeric_limits<NumberType>::is_signed &&
+                                            (!std::numeric_limits<TargetType>::is_signed || std::numeric_limits<NumberType>::digits > std::numeric_limits<TargetType>::digits) > ());
+    }
+
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_min(const NumberType /*unused*/, std::false_type /*may_fall_below*/) noexcept
+    {
+        return true;
+    }
+
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits_min(const NumberType n, std::true_type /*may_fall_below*/) noexcept
+    {
+        // NumberType is signed and either TargetType is unsigned (minimum 0)
+        // or NumberType has more digits, so it can hold the minimum
+        return n >= static_cast<NumberType>((std::numeric_limits<TargetType>::min)());
+    }
+
+    /*!
+    @brief whether integer @a n lies in the range of @a TargetType
+    */
+    template<typename TargetType, typename NumberType>
+    static constexpr bool integer_fits(const NumberType n) noexcept
+    {
+        return integer_fits_min<TargetType>(n) && integer_fits_max<TargetType>(n);
+    }
+
+    /*!
+    @brief the decimal digits of the non-negative integer @a n
+    */
+    template<typename NumberType>
+    static std::string integer_to_string(NumberType n, std::false_type /*is_signed*/)
+    {
+        std::string result;
+        do
+        {
+            result.push_back(static_cast<char>('0' + (n % 10)));
+            n = static_cast<NumberType>(n / 10);
+        }
+        while (n != 0);
+        std::reverse(result.begin(), result.end());
+        return result;
+    }
+
+    /*!
+    @brief the decimal digits of the integer @a n, with a leading '-' if it
+           is negative
+    */
+    template<typename NumberType>
+    static std::string integer_to_string(NumberType n, std::true_type /*is_signed*/)
+    {
+        // the remainder of a negative n is not positive; each digit is
+        // negated on its own, because negating the minimum of NumberType
+        // as a whole would overflow
+        const bool negative = n < 0;
+        std::string result;
+        do
+        {
+            const auto remainder = n % 10;
+            result.push_back(static_cast<char>('0' + (remainder < 0 ? -remainder : remainder)));
+            n = static_cast<NumberType>(n / 10);
+        }
+        while (n != 0);
+        if (negative)
+        {
+            result.push_back('-');
+        }
+        std::reverse(result.begin(), result.end());
+        return result;
+    }
+
+    /*!
+    @brief throws because the integer @a j is too large for @a format_name
+    @throw out_of_range.407 always
+    */
+    JSON_HEDLEY_NO_RETURN static void throw_integer_out_of_range(const BasicJsonType& j, const char* format_name, const char* range)
+    {
+        // neither std::to_string(), which has no overload for integer types
+        // wider than 64 bits, nor dump(), which would also instantiate the
+        // serializer for objects and fail for key types it cannot write
+        using integer_limits = std::numeric_limits<typename BasicJsonType::number_integer_t>;
+        using unsigned_limits = std::numeric_limits<typename BasicJsonType::number_unsigned_t>;
+        const std::string number = j.is_number_unsigned()
+                                   ? integer_to_string(j.m_data.m_value.number_unsigned, std::integral_constant<bool, unsigned_limits::is_signed>())
+                                   : integer_to_string(j.m_data.m_value.number_integer, std::integral_constant<bool, integer_limits::is_signed>());
+        static_cast<void>(number); // unused when JSON_NOEXCEPTION is defined
+        static_cast<void>(format_name);
+        static_cast<void>(range);
+        JSON_THROW(out_of_range::create(exception_id::integer_too_large, concat("integer number ", number, " cannot be represented by ", format_name, " as it does not fit ", range), &j));
+    }
+
     void write_msgpack_array_prefix(const std::size_t N, const BasicJsonType& j)
     {
         const auto n = to_msgpack_length(N, j);
@@ -23976,6 +24070,8 @@ class binary_writer
             is neither an object nor an array
     @throw out_of_range.415 if @a j is binary with a subtype that does not fit
            into a byte, before anything is written
+    @throw out_of_range.407 if @a j is an integer that does not fit the 64 bits
+           of a BSON integer, before anything is written
     @throw type_error.316 if @a j is a string that is not valid UTF-8, before
            anything is written
     @throw type_error.321 if @a j is discarded
@@ -23994,10 +24090,18 @@ class binary_writer
                 return 8ul;
 
             case value_t::number_integer:
-                return calc_bson_integer_size(j.m_data.m_value.number_integer);
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits<std::int64_t>(j.m_data.m_value.number_integer)))
+                {
+                    throw_integer_out_of_range(j, "BSON", "int64");
+                }
+                return calc_bson_integer_size(static_cast<std::int64_t>(j.m_data.m_value.number_integer));
 
             case value_t::number_unsigned:
-                return calc_bson_unsigned_size(conditional_static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::uint64_t>(j.m_data.m_value.number_unsigned)))
+                {
+                    throw_integer_out_of_range(j, "BSON", "uint64");
+                }
+                return calc_bson_unsigned_size(static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
 
             case value_t::string:
                 return calc_bson_string_size(*j.m_data.m_value.string, j);
@@ -24035,11 +24139,12 @@ class binary_writer
             case value_t::number_float:
                 return write_bson_double(name, j.m_data.m_value.number_float);
 
+            // calc_bson_value_size() checked that integers fit 64 bits
             case value_t::number_integer:
-                return write_bson_integer(name, j.m_data.m_value.number_integer);
+                return write_bson_integer(name, static_cast<std::int64_t>(j.m_data.m_value.number_integer));
 
             case value_t::number_unsigned:
-                return write_bson_unsigned(name, conditional_static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
+                return write_bson_unsigned(name, static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
 
             case value_t::string:
                 return write_bson_string(name, *j.m_data.m_value.string);
@@ -24543,7 +24648,7 @@ class binary_writer
         {
             return 'L';
         }
-        if (use_bjdata && std::is_unsigned<NumberType>::value)
+        if (use_bjdata && std::is_unsigned<NumberType>::value && integer_fits_max<std::uint64_t>(n))
         {
             return 'M';
         }
@@ -24668,14 +24773,16 @@ class binary_writer
     @brief checks whether a JSON number fits into @a TargetType
     @param[in] el a JSON number of either the signed or unsigned integer kind
     @return whether @a el's value can be represented by @a TargetType without
-            wrapping, regardless of which of the two kinds it is stored as
+            wrapping, regardless of which of the two kinds it is stored as;
+            false for a value that does not even fit the 64-bit type it is
+            read as (possible for number types wider than 64 bits)
     */
     template<typename TargetType>
     static bool bjdata_ndarray_value_in_range(const BasicJsonType& el)
     {
         return el.is_number_unsigned()
-               ? value_in_range_of<TargetType>(el.template get<std::uint64_t>())
-               : value_in_range_of<TargetType>(el.template get<std::int64_t>());
+               ? integer_fits_max<std::uint64_t>(el.m_data.m_value.number_unsigned) && value_in_range_of<TargetType>(el.template get<std::uint64_t>())
+               : integer_fits<std::int64_t>(el.m_data.m_value.number_integer) && value_in_range_of<TargetType>(el.template get<std::int64_t>());
     }
 
     /*!
@@ -24907,10 +25014,11 @@ class binary_writer
         for (const auto& el : dims)
         {
             // a dimension is read as an unsigned value below, so anything that
-            // is not a non-negative integer is rejected: a non-integer entry
-            // would pun unrelated bytes as the dimension, and a negative one
-            // would wrap into a nonsensical length
-            if (!el.is_number_integer() || (!el.is_number_unsigned() && el.template get<std::int64_t>() < 0))
+            // is not a non-negative integer in the range of std::uint64_t is
+            // rejected: a non-integer entry would pun unrelated bytes as the
+            // dimension, and a negative or wider one would wrap into a
+            // nonsensical length
+            if (!el.is_number_integer() || !bjdata_ndarray_value_in_range<std::uint64_t>(el))
             {
                 return true;
             }
@@ -25042,9 +25150,9 @@ class binary_writer
 
             case value_t::number_unsigned:
             {
-                if (j.m_data.m_value.number_unsigned > static_cast<typename BasicJsonType::number_unsigned_t>((std::numeric_limits<std::int64_t>::max)()))
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits_max<std::int64_t>(j.m_data.m_value.number_unsigned)))
                 {
-                    JSON_THROW(out_of_range::create(exception_id::integer_too_large, concat("integer number ", std::to_string(j.m_data.m_value.number_unsigned), " cannot be represented by BON8 as it does not fit int64"), &j));
+                    throw_integer_out_of_range(j, "BON8", "int64");
                 }
                 write_bon8_integer(static_cast<std::int64_t>(j.m_data.m_value.number_unsigned));
                 string_open = false;
@@ -25053,6 +25161,10 @@ class binary_writer
 
             case value_t::number_integer:
             {
+                if (JSON_HEDLEY_UNLIKELY(!integer_fits<std::int64_t>(j.m_data.m_value.number_integer)))
+                {
+                    throw_integer_out_of_range(j, "BON8", "int64");
+                }
                 write_bon8_integer(static_cast<std::int64_t>(j.m_data.m_value.number_integer));
                 string_open = false;
                 break;
@@ -27458,12 +27570,6 @@ class serializer
     using number_float_t = typename BasicJsonType::number_float_t;
     using number_integer_t = typename BasicJsonType::number_integer_t;
     using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    /// type of the absolute value of an integer: number_unsigned_t, or its
-    /// unsigned counterpart if it is signed (it may be number_integer_t, #2573)
-    using number_magnitude_t = typename std::conditional <
-                               std::is_integral<number_unsigned_t>::value && std::is_signed<number_unsigned_t>::value,
-                               std::make_unsigned<number_unsigned_t>,
-                               std::enable_if<true, number_unsigned_t >>::type::type;
     using binary_char_t = typename BasicJsonType::binary_t::value_type;
 
   public:
@@ -28642,7 +28748,7 @@ class serializer
     @param[in] x  unsigned integer number to count its digits
     @return    number of decimal digits
     */
-    unsigned int count_digits(number_magnitude_t x) noexcept
+    unsigned int count_digits(number_unsigned_t x) noexcept
     {
         unsigned int n_digits = 1;
         for (;;)
@@ -28825,7 +28931,7 @@ class serializer
         }
         auto* buffer_ptr = write_buffer.data() + write_buffer_pos;
 
-        number_magnitude_t abs_value;
+        number_unsigned_t abs_value;
 
         // one byte for the minus sign
         unsigned int n_chars = 0;
@@ -28838,7 +28944,7 @@ class serializer
         }
         else
         {
-            abs_value = static_cast<number_magnitude_t>(x);
+            abs_value = static_cast<number_unsigned_t>(x);
         }
 
         // up to 16 digits: eight at a time (as the digits of floats), written
@@ -29006,6 +29112,17 @@ class serializer
         }
     }
 
+    /*
+     * Overload to make the compiler happy while it is instantiating
+     * dump_integer for number_unsigned_t.
+     * Must never be called.
+     */
+    number_unsigned_t remove_sign(number_unsigned_t x)
+    {
+        JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
+        return x; // LCOV_EXCL_LINE
+    }
+
     /*
      * Helper function for dump_integer
      *
@@ -29015,10 +29132,10 @@ class serializer
      * absolute values of INT_MIN and INT_MAX are usually not the same. See
      * #1708 for details.
      */
-    number_magnitude_t remove_sign(number_integer_t x) noexcept
+    number_unsigned_t remove_sign(number_integer_t x) noexcept
     {
         JSON_ASSERT(x < 0);
-        return static_cast<number_magnitude_t>(-(x + 1)) + 1;
+        return static_cast<number_unsigned_t>(-(x + 1)) + 1;
     }
 
   private:
@@ -29902,22 +30019,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                   "NumberUnsignedType must be at least as wide as NumberIntegerType, "
                   "because it has to hold the absolute value of every NumberIntegerType value");
 
-    // NumberUnsignedType may be the same type as NumberIntegerType (#2573), but
-    // a repeated NumberFloatType would give overloads that collide, so it gets
-    // a readable diagnostic instead.
-    static_assert(!std::is_same<NumberFloatType, NumberIntegerType>::value && !std::is_same<NumberFloatType, NumberUnsignedType>::value,
-                  "NumberFloatType must be a different type than NumberIntegerType and NumberUnsignedType");
-
   private:
 
-    /// the kind a value of kind @a t is stored as: if number_unsigned_t is the
-    /// same type as number_integer_t, every integer is stored as number_integer
-    /// (#2573); every other kind is stored as itself
-    static constexpr value_t stored_kind(const value_t t) noexcept
-    {
-        return (std::is_same<number_integer_t, number_unsigned_t>::value && t == value_t::number_unsigned) ? value_t::number_integer : t;
-    }
-
     /// helper for exception-safe object creation
     template<typename T, typename... Args>
     JSON_HEDLEY_RETURNS_NON_NULL
@@ -29991,8 +30094,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         json_value(boolean_t v) noexcept : boolean(v) {}
         /// constructor for numbers (integer)
         json_value(number_integer_t v) noexcept : number_integer(v) {}
-        /// constructor for numbers (unsigned); takes a placeholder if number_unsigned_t is number_integer_t
-        json_value(detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType> v) noexcept : number_unsigned(v) {}
+        /// constructor for numbers (unsigned)
+        json_value(number_unsigned_t v) noexcept : number_unsigned(v) {}
         /// constructor for numbers (floating-point)
         json_value(number_float_t v) noexcept : number_float(v) {}
         /// constructor for empty values of a given type
@@ -31597,7 +31700,7 @@ public:
     /// @brief create an empty value with a given type
     /// @sa https://json.nlohmann.me/api/basic_json/basic_json/
     basic_json(const value_t v)
-        : m_data(stored_kind(v))
+        : m_data(v)
     {
         assert_invariant();
     }
@@ -31678,7 +31781,7 @@ public:
         {
             convert_leaf(val);
         }
-        JSON_ASSERT(m_data.m_type == stored_kind(val.type()));
+        JSON_ASSERT(m_data.m_type == val.type());
 
         set_parents();
         assert_invariant();
@@ -32263,16 +32366,14 @@ public:
         return m_data.m_type == value_t::number_integer ? &m_data.m_value.number_integer : nullptr;
     }
 
-    /// get a pointer to the value (unsigned number); takes a placeholder if
-    /// number_unsigned_t is number_integer_t (the integer overload handles it then)
-    number_unsigned_t* get_impl_ptr(detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>* /*unused*/) noexcept
+    /// get a pointer to the value (unsigned number)
+    number_unsigned_t* get_impl_ptr(number_unsigned_t* /*unused*/) noexcept
     {
         return is_number_unsigned() ? &m_data.m_value.number_unsigned : nullptr;
     }
 
-    /// get a pointer to the value (unsigned number); takes a placeholder if
-    /// number_unsigned_t is number_integer_t (the integer overload handles it then)
-    constexpr const number_unsigned_t* get_impl_ptr(const detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>* /*unused*/) const noexcept
+    /// get a pointer to the value (unsigned number)
+    constexpr const number_unsigned_t* get_impl_ptr(const number_unsigned_t* /*unused*/) const noexcept
     {
         return is_number_unsigned() ? &m_data.m_value.number_unsigned : nullptr;
     }

tests/src/unit-custom-array-type.cpp

@@ -9,7 +9,9 @@
 #include "doctest_compatibility.h"
 
 #include <nlohmann/json.hpp>
+using nlohmann::json;
 
+#include <cstdint>
 #include <deque>
 #include <map>
 #include <memory>
@@ -164,3 +166,47 @@ TEST_CASE("array type without at()")
     CHECK(j.at(no_at_json::json_pointer("/1")) == 2);
     CHECK_THROWS_AS(j.at(no_at_json::json_pointer("/3")), no_at_json::out_of_range);
 }
+
+TEST_CASE("regression test #5476 - array type without reserve()")
+{
+    // the capacity reserved for definite-length arrays must not require the
+    // array type to have a reserve() member function
+    SECTION("std::deque")
+    {
+        const auto j = deque_json::parse(R"({"a":[1,[2,3]],"b":[]})");
+        CHECK(j.dump() == R"({"a":[1,[2,3]],"b":[]})");
+
+        // the binary formats pass a definite length to start_array()
+        CHECK(deque_json::from_cbor(deque_json::to_cbor(j)) == j);
+        CHECK(deque_json::from_msgpack(deque_json::to_msgpack(j)) == j);
+        CHECK(deque_json::from_bon8(deque_json::to_bon8(j)) == j);
+
+        // parse() instantiates the callback parser as well, which reserves too
+        const auto with_callback = deque_json::parse(R"([1,2,3])", [](int /*depth*/, deque_json::parse_event_t /*event*/, deque_json& /*parsed*/) noexcept
+        {
+            return true;
+        });
+        CHECK(with_callback == deque_json({1, 2, 3}));
+    }
+
+    SECTION("std::vector still reserves")
+    {
+        json array = json::array();
+        for (int i = 0; i < 100; ++i)
+        {
+            array.push_back(i);
+        }
+
+        const auto j = json::from_cbor(json::to_cbor(array));
+        CHECK(j == array);
+        CHECK(j.get_ref<const json::array_t&>().capacity() >= 100);
+    }
+
+    SECTION("the reservation stays capped")
+    {
+        // CBOR array announcing 2^32-1 elements, but truncated right after the
+        // header: the input must be rejected without reserving that capacity
+        const std::vector<std::uint8_t> truncated = {0x9A, 0xFF, 0xFF, 0xFF, 0xFF};
+        CHECK(json::from_cbor(truncated, true, false).is_discarded());
+    }
+}

tests/src/unit-custom-number-types.cpp

@@ -0,0 +1,367 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+
+#include <cstdint>
+#include <limits>
+#include <map>
+#include <string>
+#include <type_traits>
+#include <vector>
+
+#if JSON_HAS_THREE_WAY_COMPARISON
+    #include <compare>
+#endif
+
+namespace custom_number_types
+{
+
+// a signed integer of class type: std::is_signed is only true for arithmetic
+// types, so the library has to take the signedness from std::numeric_limits,
+// as it does for 128-bit and multiprecision integer classes such as
+// absl::int128 or boost::multiprecision::cpp_int
+class class_int
+{
+  public:
+    // trivial, like the 128-bit integer classes: the value is stored in a union
+    class_int() = default;
+
+    // implicit from built-in integers and explicit from floats, like absl::int128;
+    // non-template overloads (as absl::int128 has) because clang 3.4 and 3.5
+    // reject basic_json's defaulted data() for a number type with template
+    // constructors
+    class_int(int v) : value(v) {} // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
+    class_int(unsigned v) : value(v) {} // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
+    class_int(long v) : value(v) {} // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
+    class_int(unsigned long v) : value(static_cast<std::int64_t>(v)) {} // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
+    class_int(long long v) : value(v) {} // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
+    class_int(unsigned long long v) : value(static_cast<std::int64_t>(v)) {} // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
+    explicit class_int(double v) : value(static_cast<std::int64_t>(v)) {}
+
+    template<typename T, typename std::enable_if<std::is_arithmetic<T>::value, int>::type = 0>
+    explicit operator T() const
+    {
+        return static_cast<T>(value);
+    }
+
+    friend bool operator==(class_int lhs, class_int rhs)
+    {
+        return lhs.value == rhs.value;
+    }
+    friend bool operator!=(class_int lhs, class_int rhs)
+    {
+        return lhs.value != rhs.value;
+    }
+    friend bool operator<(class_int lhs, class_int rhs)
+    {
+        return lhs.value < rhs.value;
+    }
+#if JSON_HAS_THREE_WAY_COMPARISON
+    friend std::strong_ordering operator<=>(class_int lhs, class_int rhs) // *NOPAD*
+    {
+        return lhs.value <=> rhs.value; // *NOPAD*
+    }
+#endif
+
+  private:
+    std::int64_t value;
+};
+
+} // namespace custom_number_types
+
+using custom_number_types::class_int;
+
+namespace std
+{
+// only the members the library uses
+template<>
+class numeric_limits<class_int>
+{
+  public:
+    static constexpr bool is_signed = true;
+    static constexpr int digits = std::numeric_limits<std::int64_t>::digits;
+};
+} // namespace std
+
+namespace
+{
+
+using class_int_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, class_int, std::uint64_t, double>;
+
+class_int_json make_class_int(std::int64_t v)
+{
+    class_int_json j(class_int_json::value_t::number_integer);
+    j.get_ref<class_int&>() = class_int(v);
+    return j;
+}
+
+} // namespace
+
+// the serializer cannot print an integer of class type, so doctest must not
+// try when an assertion fails
+namespace doctest
+{
+template<>
+struct StringMaker<class_int_json>
+{
+    static String convert(const class_int_json& j)
+    {
+        return j.type_name();
+    }
+};
+} // namespace doctest
+
+// __int128 as number type needs the std::numeric_limits (for the range checks)
+// and std::is_integral (for the serializer) specializations, which libc++
+// always provides and libstdc++ only outside strict ISO modes; the MSVC
+// standard library has none
+#if defined(__SIZEOF_INT128__) && (defined(_LIBCPP_VERSION) || defined(__GLIBCXX_TYPE_INT_N_0))
+    #define JSON_TEST_INT128_NUMBER_TYPES 1
+#else
+    #define JSON_TEST_INT128_NUMBER_TYPES 0
+#endif
+
+#if JSON_TEST_INT128_NUMBER_TYPES
+namespace
+{
+
+// __extension__ keeps -Wpedantic from flagging the non-standard type
+__extension__ typedef __int128 int128; // NOLINT(modernize-use-using)
+__extension__ typedef unsigned __int128 uint128; // NOLINT(modernize-use-using)
+
+static_assert(std::numeric_limits<int128>::digits == 127 && std::numeric_limits<uint128>::digits == 128 &&
+              std::is_integral<int128>::value && std::is_integral<uint128>::value, // NOLINT(misc-redundant-expression)
+              "__int128 is not fully supported by the standard library");
+
+using wide_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, int128, uint128, double>;
+
+wide_json make_int(int128 v)
+{
+    wide_json j(wide_json::value_t::number_integer);
+    j.get_ref<int128&>() = v;
+    return j;
+}
+
+wide_json make_uint(uint128 v)
+{
+    wide_json j(wide_json::value_t::number_unsigned);
+    j.get_ref<uint128&>() = v;
+    return j;
+}
+
+wide_json wrap(const wide_json& value)
+{
+    wide_json o(wide_json::value_t::object);
+    o["v"] = value;
+    return o;
+}
+
+} // namespace
+
+TEST_CASE("custom number types: integers beyond 64 bits")
+{
+    using out_of_range = wide_json::out_of_range;
+
+    const int128 two_64 = static_cast<int128>(1) << 64;
+    const int128 two_100 = static_cast<int128>(1) << 100;
+    const int128 max_int64 = (std::numeric_limits<std::int64_t>::max)();
+    const int128 min_int64 = (std::numeric_limits<std::int64_t>::min)();
+    const uint128 max_uint64 = (std::numeric_limits<std::uint64_t>::max)();
+
+    // before the range checks, these values were silently truncated, e.g.,
+    // 2^100 was written as 0
+    const wide_json int_big = make_int(two_100);
+    const wide_json int_big_negative = make_int(-two_100);
+    const wide_json uint_big = make_uint(static_cast<uint128>(two_100));
+    std::vector<std::uint8_t> _;
+
+    SECTION("CBOR")
+    {
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_cbor(int_big), "[json.exception.out_of_range.407] integer number 1267650600228229401496703205376 cannot be represented by CBOR as it does not fit [-2^64, 2^64-1]", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_cbor(int_big_negative), "[json.exception.out_of_range.407] integer number -1267650600228229401496703205376 cannot be represented by CBOR as it does not fit [-2^64, 2^64-1]", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_cbor(uint_big), "[json.exception.out_of_range.407] integer number 1267650600228229401496703205376 cannot be represented by CBOR as it does not fit uint64", out_of_range&);
+        // the extremes of the 128-bit types, whose digits are produced without
+        // negating the minimum as a whole
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_cbor(make_int((std::numeric_limits<int128>::min)())), "[json.exception.out_of_range.407] integer number -170141183460469231731687303715884105728 cannot be represented by CBOR as it does not fit [-2^64, 2^64-1]", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_cbor(make_int((std::numeric_limits<int128>::max)())), "[json.exception.out_of_range.407] integer number 170141183460469231731687303715884105727 cannot be represented by CBOR as it does not fit [-2^64, 2^64-1]", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_cbor(make_uint((std::numeric_limits<uint128>::max)())), "[json.exception.out_of_range.407] integer number 340282366920938463463374607431768211455 cannot be represented by CBOR as it does not fit uint64", out_of_range&);
+        CHECK_THROWS_AS(_ = wide_json::to_cbor(make_int(two_64)), out_of_range&);
+        CHECK_THROWS_AS(_ = wide_json::to_cbor(make_int(-two_64 - 1)), out_of_range&);
+        CHECK_THROWS_AS(_ = wide_json::to_cbor(make_uint(static_cast<uint128>(max_uint64) + 1)), out_of_range&);
+
+        // CBOR's integers cover [-2^64, 2^64-1]
+        CHECK(wide_json::to_cbor(make_int(two_64 - 1)) == std::vector<std::uint8_t>({0x1B, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}));
+        CHECK(wide_json::to_cbor(make_int(-two_64)) == std::vector<std::uint8_t>({0x3B, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}));
+        CHECK(wide_json::to_cbor(make_uint(max_uint64)) == std::vector<std::uint8_t>({0x1B, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}));
+    }
+
+    SECTION("MessagePack")
+    {
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_msgpack(int_big), "[json.exception.out_of_range.407] integer number 1267650600228229401496703205376 cannot be represented by MessagePack as it does not fit [-2^63, 2^64-1]", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_msgpack(int_big_negative), "[json.exception.out_of_range.407] integer number -1267650600228229401496703205376 cannot be represented by MessagePack as it does not fit [-2^63, 2^64-1]", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_msgpack(uint_big), "[json.exception.out_of_range.407] integer number 1267650600228229401496703205376 cannot be represented by MessagePack as it does not fit uint64", out_of_range&);
+        CHECK_THROWS_AS(_ = wide_json::to_msgpack(make_int(two_64)), out_of_range&);
+        CHECK_THROWS_AS(_ = wide_json::to_msgpack(make_int(min_int64 - 1)), out_of_range&);
+
+        // MessagePack's integers cover [-2^63, 2^64-1]
+        CHECK(wide_json::to_msgpack(make_int(two_64 - 1)) == std::vector<std::uint8_t>({0xCF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}));
+        CHECK(wide_json::to_msgpack(make_int(min_int64)) == std::vector<std::uint8_t>({0xD3, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}));
+        CHECK(wide_json::to_msgpack(make_uint(max_uint64)) == std::vector<std::uint8_t>({0xCF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}));
+    }
+
+    SECTION("BSON")
+    {
+        // wrap() stores the value at /v, which JSON_DIAGNOSTICS adds to the message
+#if JSON_DIAGNOSTICS
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_bson(wrap(int_big)), "[json.exception.out_of_range.407] (/v) integer number 1267650600228229401496703205376 cannot be represented by BSON as it does not fit int64", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_bson(wrap(int_big_negative)), "[json.exception.out_of_range.407] (/v) integer number -1267650600228229401496703205376 cannot be represented by BSON as it does not fit int64", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_bson(wrap(uint_big)), "[json.exception.out_of_range.407] (/v) integer number 1267650600228229401496703205376 cannot be represented by BSON as it does not fit uint64", out_of_range&);
+#else
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_bson(wrap(int_big)), "[json.exception.out_of_range.407] integer number 1267650600228229401496703205376 cannot be represented by BSON as it does not fit int64", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_bson(wrap(int_big_negative)), "[json.exception.out_of_range.407] integer number -1267650600228229401496703205376 cannot be represented by BSON as it does not fit int64", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_bson(wrap(uint_big)), "[json.exception.out_of_range.407] integer number 1267650600228229401496703205376 cannot be represented by BSON as it does not fit uint64", out_of_range&);
+#endif
+        CHECK_THROWS_AS(_ = wide_json::to_bson(wrap(make_int(max_int64 + 1))), out_of_range&);
+        CHECK_THROWS_AS(_ = wide_json::to_bson(wrap(make_int(min_int64 - 1))), out_of_range&);
+
+        // nested values are checked as well, before anything is written
+        wide_json nested(wide_json::value_t::object);
+        nested["a"] = wide_json::array({wrap(int_big)});
+        std::vector<std::uint8_t> out;
+        CHECK_THROWS_AS(wide_json::to_bson(nested, out), out_of_range&);
+        CHECK(out.empty());
+
+        CHECK(wide_json::from_bson(wide_json::to_bson(wrap(make_int(max_int64)))) == wrap(make_int(max_int64)));
+        CHECK(wide_json::from_bson(wide_json::to_bson(wrap(make_int(min_int64)))) == wrap(make_int(min_int64)));
+        CHECK_NOTHROW(wide_json::to_bson(wrap(make_uint(max_uint64))));
+    }
+
+    SECTION("BON8")
+    {
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_bon8(int_big), "[json.exception.out_of_range.407] integer number 1267650600228229401496703205376 cannot be represented by BON8 as it does not fit int64", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_bon8(int_big_negative), "[json.exception.out_of_range.407] integer number -1267650600228229401496703205376 cannot be represented by BON8 as it does not fit int64", out_of_range&);
+        CHECK_THROWS_WITH_AS(_ = wide_json::to_bon8(uint_big), "[json.exception.out_of_range.407] integer number 1267650600228229401496703205376 cannot be represented by BON8 as it does not fit int64", out_of_range&);
+        CHECK_THROWS_AS(_ = wide_json::to_bon8(make_int(max_int64 + 1)), out_of_range&);
+        CHECK_THROWS_AS(_ = wide_json::to_bon8(make_int(min_int64 - 1)), out_of_range&);
+
+        CHECK(wide_json::from_bon8(wide_json::to_bon8(make_int(max_int64))) == make_int(max_int64));
+        CHECK(wide_json::from_bon8(wide_json::to_bon8(make_int(min_int64))) == make_int(min_int64));
+    }
+
+    SECTION("UBJSON and BJData")
+    {
+        // integers beyond 64 bits are written exactly as high-precision numbers
+        const std::string digits = "1267650600228229401496703205376";
+        std::vector<std::uint8_t> expected = {'H', 'i', static_cast<std::uint8_t>(digits.size())};
+        expected.insert(expected.end(), digits.begin(), digits.end());
+        CHECK(wide_json::to_ubjson(int_big) == expected);
+        CHECK(wide_json::to_ubjson(uint_big) == expected);
+        CHECK(wide_json::to_bjdata(int_big) == expected);
+        // BJData's uint64 marker 'M' was used for any unsigned value beyond
+        // int64, which truncated the ones beyond 64 bits
+        CHECK(wide_json::to_bjdata(uint_big) == expected);
+
+        // the uint64 marker is still used where the value fits
+        CHECK(wide_json::to_bjdata(make_uint(max_uint64)) == std::vector<std::uint8_t>({'M', 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}));
+
+        // the elements of an optimized container are written the same way;
+        // BJData does not allow 'H' as the type of an optimized container
+        std::vector<std::uint8_t> expected_ubjson_array = {'[', '$', 'H', '#', 'i', 2};
+        std::vector<std::uint8_t> expected_bjdata_array = {'[', '#', 'i', 2};
+        for (int i = 0; i < 2; ++i)
+        {
+            expected_ubjson_array.insert(expected_ubjson_array.end(), expected.begin() + 1, expected.end());
+            expected_bjdata_array.insert(expected_bjdata_array.end(), expected.begin(), expected.end());
+        }
+        CHECK(wide_json::to_ubjson(wide_json::array({uint_big, uint_big}), true, true) == expected_ubjson_array);
+        CHECK(wide_json::to_bjdata(wide_json::array({uint_big, uint_big}), true, true) == expected_bjdata_array);
+    }
+
+    SECTION("BJData ND-array")
+    {
+        // an ND-array element beyond 64 bits does not fit any dtype, so the
+        // annotated object is written as a plain object instead of truncating
+        // the element into range
+        wide_json element(wide_json::value_t::object);
+        element["_ArrayType_"] = "uint8";
+        element["_ArraySize_"] = wide_json::array({make_uint(2), make_uint(1)});
+        element["_ArrayData_"] = wide_json::array({make_uint(1), make_uint(static_cast<uint128>(two_64) + 1)});
+        const auto element_bytes = wide_json::to_bjdata(element, true, true);
+        REQUIRE(!element_bytes.empty());
+        CHECK(element_bytes[0] == '{');
+
+        wide_json signed_element = element;
+        signed_element["_ArrayType_"] = "int8";
+        signed_element["_ArrayData_"] = wide_json::array({make_int(1), make_int(-two_64 + 1)});
+        const auto signed_element_bytes = wide_json::to_bjdata(signed_element, true, true);
+        REQUIRE(!signed_element_bytes.empty());
+        CHECK(signed_element_bytes[0] == '{');
+
+        // the same for a dimension beyond 64 bits, which wrapped into a
+        // dimension matching the size of _ArrayData_ (here: 1)
+        wide_json dimension = element;
+        dimension["_ArraySize_"] = wide_json::array({make_uint(2), make_uint(static_cast<uint128>(two_64) + 1)});
+        dimension["_ArrayData_"] = wide_json::array({make_uint(1), make_uint(2)});
+        const auto dimension_bytes = wide_json::to_bjdata(dimension, true, true);
+        REQUIRE(!dimension_bytes.empty());
+        CHECK(dimension_bytes[0] == '{');
+
+        // in range, the ND-array is still written
+        wide_json fits = element;
+        fits["_ArrayData_"] = wide_json::array({make_uint(1), make_uint(2)});
+        const auto fits_bytes = wide_json::to_bjdata(fits, true, true);
+        REQUIRE(!fits_bytes.empty());
+        CHECK(fits_bytes[0] == '[');
+    }
+}
+
+#endif
+
+TEST_CASE("custom number types")
+{
+    SECTION("signed integer of class type compared with a float")
+    {
+        // std::is_signed is false for a class type, which made the comparison
+        // treat any float below zero as less than every integer
+        const class_int_json minus_five = make_class_int(-5);
+        const class_int_json minus_two = make_class_int(-2);
+        const class_int_json five = make_class_int(5);
+        const class_int_json minus_two_and_a_half = -2.5;
+        const class_int_json two_and_a_half = 2.5;
+        const class_int_json huge_negative = -1e30;
+        const class_int_json huge_positive = 1e30;
+
+        CHECK(minus_five < minus_two_and_a_half);
+        CHECK_FALSE(minus_two_and_a_half < minus_five);
+        CHECK(minus_two_and_a_half > minus_five);
+        CHECK(minus_five <= minus_two_and_a_half);
+        CHECK(minus_two_and_a_half >= minus_five);
+        CHECK(minus_five != minus_two_and_a_half);
+
+        CHECK(minus_two_and_a_half < minus_two);
+        CHECK_FALSE(minus_two < minus_two_and_a_half);
+
+        CHECK(two_and_a_half < five);
+        CHECK(minus_five < two_and_a_half);
+
+        // floats beyond the integer's range
+        CHECK(huge_negative < minus_five);
+        CHECK_FALSE(minus_five < huge_negative);
+        CHECK(five < huge_positive);
+        CHECK_FALSE(huge_positive < five);
+
+        // equality
+        const class_int_json minus_two_float = -2.0;
+        CHECK(minus_two == minus_two_float);
+        CHECK(minus_two_float == minus_two);
+    }
+
+}

tests/src/unit-msgpack-custom-types.cpp

@@ -0,0 +1,296 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+// MessagePack tests with basic_json specializations other than nlohmann::json;
+// they are kept apart from unit-msgpack.cpp because every specialization adds
+// many sections to the object file, and MinGW cannot link objects with more
+// than 65535 sections (see the clang job in .github/workflows/windows.yml)
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <cstdint> // SIZE_MAX, UINT32_MAX
+#include <functional>
+#include <limits>
+#include <map>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+// the fake sizes below do not fit into a 32-bit std::size_t
+// with clang and libstdc++ 10, the std::filesystem::path conversion that
+// C++17 builds consider for every string type is ambiguous for a class
+// derived from std::string, so the string case is not tested there
+#if !(defined(__clang__) && defined(_GLIBCXX_RELEASE) && _GLIBCXX_RELEASE < 11)
+    #define JSON_TEST_BEYOND_UINT32_STRING 1
+#endif
+
+#if SIZE_MAX > UINT32_MAX
+template<typename T, typename A = std::allocator<T>>
+struct huge_array : std::vector<T, A>
+{
+    using base = std::vector<T, A>;
+    using base::base;
+
+    bool fake_size = false;
+
+    std::size_t size() const noexcept
+    {
+        if (fake_size)
+        {
+            return (std::numeric_limits<std::uint32_t>::max)() + 1ULL;
+        }
+
+        return base::size();
+    }
+};
+
+using huge_array_json = nlohmann::json::with_array_t<huge_array>;
+
+TEST_CASE("MessagePack Size above uint32 for array")
+{
+    huge_array_json j = huge_array_json::array();
+
+    j.push_back(1);
+    j.push_back(2);
+    j.push_back(3);
+
+    auto& array = j.get_ref<huge_array_json::array_t&>();
+    array.fake_size = true;
+
+    // write into a caller-owned vector: to_msgpack(j) reserves space based on
+    // the (faked) element count, which fails with bad_alloc on Windows
+    std::vector<std::uint8_t> result;
+    CHECK_THROWS_WITH_AS(
+        huge_array_json::to_msgpack(j, result),
+        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
+        json::out_of_range&);
+
+    array.fake_size = false;
+}
+
+template<typename K, typename V,
+         typename C = std::less<K>,
+         typename A = std::allocator<std::pair<const K, V>>>
+                                     struct huge_map : std::map<K, V, C, A>
+{
+    using base = std::map<K, V, C, A>;
+    using base::base;
+
+    bool fake_size = false;
+
+    std::size_t size() const noexcept
+    {
+        if (fake_size)
+        {
+            return static_cast<std::size_t>(UINT32_MAX) + 1ULL;
+        }
+
+        return base::size();
+    }
+};
+
+using huge_object_json = nlohmann::json::with_object_t<huge_map>;
+
+TEST_CASE("MessagePack Size above uint32 for object")
+{
+
+    huge_object_json j = huge_object_json::object();
+
+    j["one"] = 1;
+    j["two"] = 2;
+
+    auto& object = j.get_ref<huge_object_json::object_t&>();
+    object.fake_size = true;
+
+    // write into a caller-owned vector: to_msgpack(j) reserves space based on
+    // the (faked) element count, which fails with bad_alloc on Windows
+    std::vector<std::uint8_t> result;
+    CHECK_THROWS_WITH_AS(
+        huge_object_json::to_msgpack(j, result),
+        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
+        json::out_of_range&);
+
+    object.fake_size = false;
+}
+
+#ifdef JSON_TEST_BEYOND_UINT32_STRING
+struct huge_string : std::string
+{
+    using std::string::string;
+
+    std::size_t size() const noexcept // NOLINT(readability-convert-member-functions-to-static)
+    {
+        return static_cast<std::size_t>(UINT32_MAX) + 1ULL;
+    }
+};
+
+using huge_string_json = nlohmann::json::with_string_t<huge_string>;
+
+TEST_CASE("MessagePack Size above uint32 for string")
+{
+    const huge_string_json j = "hello";
+
+    CHECK_THROWS_WITH_AS(
+        huge_string_json::to_msgpack(j),
+        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
+        json::out_of_range&);
+}
+#endif
+
+struct huge_binary : std::vector<std::uint8_t>
+{
+    using std::vector<std::uint8_t>::vector;
+
+    std::size_t size() const noexcept // NOLINT(readability-convert-member-functions-to-static)
+    {
+        return static_cast<std::size_t>(UINT32_MAX) + 1ULL;
+    }
+};
+
+using huge_binary_json = nlohmann::json::with_binary_t<huge_binary>;
+
+TEST_CASE("MessagePack Size above uint32 for binary")
+{
+
+    huge_binary_json j = huge_binary_json::binary(huge_binary{});
+
+    j.get_binary().push_back(0x01);
+    j.get_binary().push_back(0x02);
+
+    CHECK_THROWS_WITH_AS(
+        huge_binary_json::to_msgpack(j),
+        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
+        json::out_of_range&);
+}
+#endif
+
+namespace
+{
+// types that report a size beyond UINT32_MAX without allocating that much
+// memory, so the MessagePack length limit can be tested cheaply; see the
+// similar types in unit-bson.cpp
+std::size_t beyond_uint32_size()
+{
+    return static_cast<std::size_t>((std::numeric_limits<std::uint32_t>::max)()) + 1;
+}
+
+class beyond_uint32_binary_t : public std::vector<std::uint8_t>
+{
+  public:
+    using std::vector<std::uint8_t>::vector;
+
+    size_type size() const noexcept // NOLINT(readability-convert-member-functions-to-static)
+    {
+        return beyond_uint32_size();
+    }
+};
+
+#ifdef JSON_TEST_BEYOND_UINT32_STRING
+class beyond_uint32_string_t : public std::string
+{
+  public:
+    using std::string::string;
+
+    size_type size() const noexcept // NOLINT(readability-convert-member-functions-to-static)
+    {
+        return beyond_uint32_size();
+    }
+};
+
+using beyond_uint32_string_json = nlohmann::json::with_string_t<beyond_uint32_string_t>;
+#endif
+
+using beyond_uint32_binary_json = nlohmann::json::with_binary_t<beyond_uint32_binary_t>;
+} // namespace
+
+TEST_CASE("MessagePack lengths beyond UINT32_MAX cannot be serialized")
+{
+    // MessagePack stores the length of a string, binary value, array, or
+    // object in at most 32 bits; a larger one used to be written without any
+    // length at all
+#if SIZE_MAX > UINT32_MAX
+    {
+        const char* const expected = "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295";
+
+        const beyond_uint32_binary_json binary = beyond_uint32_binary_json::binary(beyond_uint32_binary_t{});
+        CHECK_THROWS_WITH_AS(beyond_uint32_binary_json::to_msgpack(binary), expected, beyond_uint32_binary_json::out_of_range&);
+
+        const beyond_uint32_binary_json ext = beyond_uint32_binary_json::binary(beyond_uint32_binary_t{}, 42);
+        CHECK_THROWS_WITH_AS(beyond_uint32_binary_json::to_msgpack(ext), expected, beyond_uint32_binary_json::out_of_range&);
+
+#ifdef JSON_TEST_BEYOND_UINT32_STRING
+        // created from its type rather than from a beyond_uint32_string_t:
+        // that would consider the std::filesystem::path conversion, which
+        // libstdc++ 10 cannot decide for a class derived from std::string
+        const beyond_uint32_string_json string(beyond_uint32_string_json::value_t::string);
+        CHECK_THROWS_WITH_AS(beyond_uint32_string_json::to_msgpack(string), expected, beyond_uint32_string_json::out_of_range&);
+#endif
+    }
+#endif
+}
+
+TEST_CASE("MessagePack numbers use the active union member (see #5644)")
+{
+    // when number_integer_t is narrower than number_unsigned_t, to_msgpack()
+    // used to read the union member that was not the active one, writing
+    // wrong bytes for some values; std::int64_t/std::uint64_t (the default
+    // types, where both members have the same width) were not affected
+    using int32_json = nlohmann::json::with_integers_t<std::int32_t, std::uint64_t>;
+    using int16_json = nlohmann::json::with_integers_t<std::int16_t, std::uint64_t>;
+
+    SECTION("number_integer_t = std::int32_t")
+    {
+        SECTION("6442450944 (uint 64; the low 32 bits used to be sign-extended)")
+        {
+            const int32_json j = 6442450944ULL;
+            CHECK(j.is_number_unsigned());
+
+            std::vector<uint8_t> const expected{0xcf, 0x00, 0x00, 0x00, 0x01, 0x80, 0x00, 0x00, 0x00};
+            const auto result = int32_json::to_msgpack(j);
+            CHECK(result == expected);
+            CHECK(int32_json::from_msgpack(result) == j);
+        }
+
+        SECTION("4294967496 (uint 64; the low 32 bits used to be the whole value)")
+        {
+            const int32_json j = 4294967496ULL;
+            CHECK(j.is_number_unsigned());
+
+            std::vector<uint8_t> const expected{0xcf, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0xc8};
+            const auto result = int32_json::to_msgpack(j);
+            CHECK(result == expected);
+            CHECK(int32_json::from_msgpack(result) == j);
+        }
+    }
+
+    SECTION("number_integer_t = std::int16_t, 98304 (uint 32)")
+    {
+        const int16_json j = 98304ULL;
+        CHECK(j.is_number_unsigned());
+
+        std::vector<uint8_t> const expected{0xce, 0x00, 0x01, 0x80, 0x00};
+        const auto result = int16_json::to_msgpack(j);
+        CHECK(result == expected);
+        CHECK(int16_json::from_msgpack(result) == j);
+    }
+
+    SECTION("default types (std::int64_t/std::uint64_t) are unaffected")
+    {
+        const json j = 4294967496ULL;
+        CHECK(j.is_number_unsigned());
+
+        std::vector<uint8_t> const expected{0xcf, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0xc8};
+        const auto result = json::to_msgpack(j);
+        CHECK(result == expected);
+        CHECK(json::from_msgpack(result) == j);
+    }
+}

tests/src/unit-msgpack.cpp

@@ -2173,276 +2173,6 @@ TEST_CASE("MessagePack roundtrips" * doctest::skip())
     }
 }
 
-// the fake sizes below do not fit into a 32-bit std::size_t
-// with clang and libstdc++ 10, the std::filesystem::path conversion that
-// C++17 builds consider for every string type is ambiguous for a class
-// derived from std::string, so the string case is not tested there
-#if !(defined(__clang__) && defined(_GLIBCXX_RELEASE) && _GLIBCXX_RELEASE < 11)
-    #define JSON_TEST_BEYOND_UINT32_STRING 1
-#endif
-
-#if SIZE_MAX > UINT32_MAX
-template<typename T, typename A = std::allocator<T>>
-struct huge_array : std::vector<T, A>
-{
-    using base = std::vector<T, A>;
-    using base::base;
-
-    bool fake_size = false;
-
-    std::size_t size() const noexcept
-    {
-        if (fake_size)
-        {
-            return (std::numeric_limits<std::uint32_t>::max)() + 1ULL;
-        }
-
-        return base::size();
-    }
-};
-
-using huge_array_json = nlohmann::json::with_array_t<huge_array>;
-
-TEST_CASE("MessagePack Size above uint32 for array")
-{
-    huge_array_json j = huge_array_json::array();
-
-    j.push_back(1);
-    j.push_back(2);
-    j.push_back(3);
-
-    auto& array = j.get_ref<huge_array_json::array_t&>();
-    array.fake_size = true;
-
-    // write into a caller-owned vector: to_msgpack(j) reserves space based on
-    // the (faked) element count, which fails with bad_alloc on Windows
-    std::vector<std::uint8_t> result;
-    CHECK_THROWS_WITH_AS(
-        huge_array_json::to_msgpack(j, result),
-        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
-        json::out_of_range&);
-
-    array.fake_size = false;
-}
-
-template<typename K, typename V,
-         typename C = std::less<K>,
-         typename A = std::allocator<std::pair<const K, V>>>
-                                     struct huge_map : std::map<K, V, C, A>
-{
-    using base = std::map<K, V, C, A>;
-    using base::base;
-
-    bool fake_size = false;
-
-    std::size_t size() const noexcept
-    {
-        if (fake_size)
-        {
-            return static_cast<std::size_t>(UINT32_MAX) + 1ULL;
-        }
-
-        return base::size();
-    }
-};
-
-using huge_object_json = nlohmann::json::with_object_t<huge_map>;
-
-TEST_CASE("MessagePack Size above uint32 for object")
-{
-
-    huge_object_json j = huge_object_json::object();
-
-    j["one"] = 1;
-    j["two"] = 2;
-
-    auto& object = j.get_ref<huge_object_json::object_t&>();
-    object.fake_size = true;
-
-    // write into a caller-owned vector: to_msgpack(j) reserves space based on
-    // the (faked) element count, which fails with bad_alloc on Windows
-    std::vector<std::uint8_t> result;
-    CHECK_THROWS_WITH_AS(
-        huge_object_json::to_msgpack(j, result),
-        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
-        json::out_of_range&);
-
-    object.fake_size = false;
-}
-
-#ifdef JSON_TEST_BEYOND_UINT32_STRING
-struct huge_string : std::string
-{
-    using std::string::string;
-
-    std::size_t size() const noexcept // NOLINT(readability-convert-member-functions-to-static)
-    {
-        return static_cast<std::size_t>(UINT32_MAX) + 1ULL;
-    }
-};
-
-using huge_string_json = nlohmann::json::with_string_t<huge_string>;
-
-TEST_CASE("MessagePack Size above uint32 for string")
-{
-    const huge_string_json j = "hello";
-
-    CHECK_THROWS_WITH_AS(
-        huge_string_json::to_msgpack(j),
-        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
-        json::out_of_range&);
-}
-#endif
-
-struct huge_binary : std::vector<std::uint8_t>
-{
-    using std::vector<std::uint8_t>::vector;
-
-    std::size_t size() const noexcept // NOLINT(readability-convert-member-functions-to-static)
-    {
-        return static_cast<std::size_t>(UINT32_MAX) + 1ULL;
-    }
-};
-
-using huge_binary_json = nlohmann::json::with_binary_t<huge_binary>;
-
-TEST_CASE("MessagePack Size above uint32 for binary")
-{
-
-    huge_binary_json j = huge_binary_json::binary(huge_binary{});
-
-    j.get_binary().push_back(0x01);
-    j.get_binary().push_back(0x02);
-
-    CHECK_THROWS_WITH_AS(
-        huge_binary_json::to_msgpack(j),
-        "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295",
-        json::out_of_range&);
-}
-#endif
-
-namespace
-{
-// types that report a size beyond UINT32_MAX without allocating that much
-// memory, so the MessagePack length limit can be tested cheaply; see the
-// similar types in unit-bson.cpp
-std::size_t beyond_uint32_size()
-{
-    return static_cast<std::size_t>((std::numeric_limits<std::uint32_t>::max)()) + 1;
-}
-
-class beyond_uint32_binary_t : public std::vector<std::uint8_t>
-{
-  public:
-    using std::vector<std::uint8_t>::vector;
-
-    size_type size() const noexcept // NOLINT(readability-convert-member-functions-to-static)
-    {
-        return beyond_uint32_size();
-    }
-};
-
-#ifdef JSON_TEST_BEYOND_UINT32_STRING
-class beyond_uint32_string_t : public std::string
-{
-  public:
-    using std::string::string;
-
-    size_type size() const noexcept // NOLINT(readability-convert-member-functions-to-static)
-    {
-        return beyond_uint32_size();
-    }
-};
-
-using beyond_uint32_string_json = nlohmann::json::with_string_t<beyond_uint32_string_t>;
-#endif
-
-using beyond_uint32_binary_json = nlohmann::json::with_binary_t<beyond_uint32_binary_t>;
-} // namespace
-
-TEST_CASE("MessagePack lengths beyond UINT32_MAX cannot be serialized")
-{
-    // MessagePack stores the length of a string, binary value, array, or
-    // object in at most 32 bits; a larger one used to be written without any
-    // length at all
-#if SIZE_MAX > UINT32_MAX
-    {
-        const char* const expected = "[json.exception.out_of_range.412] MessagePack length 4294967296 exceeds maximum of 4294967295";
-
-        const beyond_uint32_binary_json binary = beyond_uint32_binary_json::binary(beyond_uint32_binary_t{});
-        CHECK_THROWS_WITH_AS(beyond_uint32_binary_json::to_msgpack(binary), expected, beyond_uint32_binary_json::out_of_range&);
-
-        const beyond_uint32_binary_json ext = beyond_uint32_binary_json::binary(beyond_uint32_binary_t{}, 42);
-        CHECK_THROWS_WITH_AS(beyond_uint32_binary_json::to_msgpack(ext), expected, beyond_uint32_binary_json::out_of_range&);
-
-#ifdef JSON_TEST_BEYOND_UINT32_STRING
-        // created from its type rather than from a beyond_uint32_string_t:
-        // that would consider the std::filesystem::path conversion, which
-        // libstdc++ 10 cannot decide for a class derived from std::string
-        const beyond_uint32_string_json string(beyond_uint32_string_json::value_t::string);
-        CHECK_THROWS_WITH_AS(beyond_uint32_string_json::to_msgpack(string), expected, beyond_uint32_string_json::out_of_range&);
-#endif
-    }
-#endif
-}
-
-TEST_CASE("MessagePack numbers use the active union member (see #5644)")
-{
-    // when number_integer_t is narrower than number_unsigned_t, to_msgpack()
-    // used to read the union member that was not the active one, writing
-    // wrong bytes for some values; std::int64_t/std::uint64_t (the default
-    // types, where both members have the same width) were not affected
-    using int32_json = nlohmann::json::with_integers_t<std::int32_t, std::uint64_t>;
-    using int16_json = nlohmann::json::with_integers_t<std::int16_t, std::uint64_t>;
-
-    SECTION("number_integer_t = std::int32_t")
-    {
-        SECTION("6442450944 (uint 64; the low 32 bits used to be sign-extended)")
-        {
-            const int32_json j = 6442450944ULL;
-            CHECK(j.is_number_unsigned());
-
-            std::vector<uint8_t> const expected{0xcf, 0x00, 0x00, 0x00, 0x01, 0x80, 0x00, 0x00, 0x00};
-            const auto result = int32_json::to_msgpack(j);
-            CHECK(result == expected);
-            CHECK(int32_json::from_msgpack(result) == j);
-        }
-
-        SECTION("4294967496 (uint 64; the low 32 bits used to be the whole value)")
-        {
-            const int32_json j = 4294967496ULL;
-            CHECK(j.is_number_unsigned());
-
-            std::vector<uint8_t> const expected{0xcf, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0xc8};
-            const auto result = int32_json::to_msgpack(j);
-            CHECK(result == expected);
-            CHECK(int32_json::from_msgpack(result) == j);
-        }
-    }
-
-    SECTION("number_integer_t = std::int16_t, 98304 (uint 32)")
-    {
-        const int16_json j = 98304ULL;
-        CHECK(j.is_number_unsigned());
-
-        std::vector<uint8_t> const expected{0xce, 0x00, 0x01, 0x80, 0x00};
-        const auto result = int16_json::to_msgpack(j);
-        CHECK(result == expected);
-        CHECK(int16_json::from_msgpack(result) == j);
-    }
-
-    SECTION("default types (std::int64_t/std::uint64_t) are unaffected")
-    {
-        const json j = 4294967496ULL;
-        CHECK(j.is_number_unsigned());
-
-        std::vector<uint8_t> const expected{0xcf, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0xc8};
-        const auto result = json::to_msgpack(j);
-        CHECK(result == expected);
-        CHECK(json::from_msgpack(result) == j);
-    }
-}
-
 TEST_CASE("MessagePack large strings and binaries (chunked reader)")
 {
     // get_msgpack_string()/get_msgpack_binary() both read through get_binary(),

tests/src/unit-regression3.cpp

@@ -43,7 +43,6 @@ using ordered_json = nlohmann::ordered_json;
 #endif
 
 #include <cstdio>
-#include <deque>
 #include <list>
 #include <type_traits>
 #include <utility>
@@ -867,52 +866,6 @@ TEST_CASE("issue #5402 - update(merge_objects=true) overwrites a primitive with
 }
 
 
-TEST_CASE("regression test #5476 - array type without reserve()")
-{
-    // the capacity reserved for definite-length arrays must not require the
-    // array type to have a reserve() member function
-    using deque_json = nlohmann::json::with_array_t<std::deque>;
-
-    SECTION("std::deque")
-    {
-        const auto j = deque_json::parse(R"({"a":[1,[2,3]],"b":[]})");
-        CHECK(j.dump() == R"({"a":[1,[2,3]],"b":[]})");
-
-        // the binary formats pass a definite length to start_array()
-        CHECK(deque_json::from_cbor(deque_json::to_cbor(j)) == j);
-        CHECK(deque_json::from_msgpack(deque_json::to_msgpack(j)) == j);
-        CHECK(deque_json::from_bon8(deque_json::to_bon8(j)) == j);
-
-        // parse() instantiates the callback parser as well, which reserves too
-        const auto with_callback = deque_json::parse(R"([1,2,3])", [](int /*depth*/, deque_json::parse_event_t /*event*/, deque_json& /*parsed*/) noexcept
-        {
-            return true;
-        });
-        CHECK(with_callback == deque_json({1, 2, 3}));
-    }
-
-    SECTION("std::vector still reserves")
-    {
-        json array = json::array();
-        for (int i = 0; i < 100; ++i)
-        {
-            array.push_back(i);
-        }
-
-        const auto j = json::from_cbor(json::to_cbor(array));
-        CHECK(j == array);
-        CHECK(j.get_ref<const json::array_t&>().capacity() >= 100);
-    }
-
-    SECTION("the reservation stays capped")
-    {
-        // CBOR array announcing 2^32-1 elements, but truncated right after the
-        // header: the input must be rejected without reserving that capacity
-        const std::vector<std::uint8_t> truncated = {0x9A, 0xFF, 0xFF, 0xFF, 0xFF};
-        CHECK(json::from_cbor(truncated, true, false).is_discarded());
-    }
-}
-
 TEST_CASE("issue #5317 - nested indefinite-length CBOR string chunks are rejected")
 {
     json _;

tests/src/unit-same-number-types.cpp

@@ -1,201 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
-// |  |  |__   |  |  | | | |  version 3.12.0
-// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
-//
-// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
-// SPDX-License-Identifier: MIT
-
-#include "doctest_compatibility.h"
-
-#include <nlohmann/json.hpp>
-
-#include <cstdint>
-#include <functional>
-#include <limits>
-#include <string>
-#include <vector>
-
-// basic_json with the same type for number_integer_t and number_unsigned_t
-// (#2573): every integer is stored as number_integer
-
-namespace
-{
-
-template<typename IntegerType>
-using same_types_json = nlohmann::json::with_integers_t<IntegerType, IntegerType>;
-
-using json64 = same_types_json<std::int64_t>;
-using json32 = same_types_json<std::int32_t>;
-
-} // namespace
-
-TEST_CASE_TEMPLATE("same type for number_integer_t and number_unsigned_t", Json, json64, json32)
-{
-    using integer_t = typename Json::number_integer_t;
-    using limits = std::numeric_limits<integer_t>;
-
-    SECTION("parsing stores integers as number_integer")
-    {
-        const Json j = Json::parse("[0, 1, -1, 2147483647, -2147483648]");
-        for (const auto& element : j)
-        {
-            CHECK(element.is_number_integer());
-            CHECK(!element.is_number_unsigned());
-            CHECK(element.type() == nlohmann::detail::value_t::number_integer);
-        }
-        CHECK(j[1].template get<integer_t>() == 1);
-        CHECK(j[2].template get<integer_t>() == -1);
-        CHECK(j[3].template get<integer_t>() == 2147483647);
-        CHECK(j[4].template get<std::int64_t>() == -2147483648LL);
-    }
-
-    SECTION("integers above the maximum are parsed as floats")
-    {
-        // a positive literal is parsed as unsigned first; it must not wrap
-        // around to a negative number_integer_t
-        const auto above_max = std::to_string(static_cast<std::uint64_t>(limits::max()) + 1);
-        const Json j1 = Json::parse(above_max);
-        CHECK(j1.is_number_float());
-        CHECK(j1.template get<double>() == static_cast<double>(static_cast<std::uint64_t>(limits::max()) + 1));
-
-        const Json j2 = Json::parse("18446744073709551615");
-        CHECK(j2.is_number_float());
-        CHECK(j2.template get<double>() == 18446744073709551615.0);
-
-        const Json j3 = Json::parse(std::to_string(limits::max()));
-        CHECK(j3.is_number_integer());
-        CHECK(j3.template get<integer_t>() == limits::max());
-    }
-
-    SECTION("serialization of the extremes")
-    {
-        CHECK(Json(limits::max()).dump() == std::to_string(limits::max()));
-        // the absolute value of the minimum does not fit into number_unsigned_t
-        CHECK(Json(limits::min()).dump() == std::to_string(limits::min()));
-        CHECK(Json::parse(std::to_string(limits::min())) == Json(limits::min()));
-        CHECK(Json(0).dump() == "0");
-    }
-
-    SECTION("construction from unsigned types")
-    {
-        const Json j1 = 5u;
-        CHECK(j1.is_number_integer());
-        CHECK(!j1.is_number_unsigned());
-        CHECK(j1 == 5);
-
-        const Json j2 = static_cast<std::uint8_t>(200);
-        CHECK(j2.is_number_integer());
-        CHECK(j2.template get<integer_t>() == 200);
-
-        const Json j3 = std::vector<unsigned> {1, 2, 3};
-        CHECK(j3.dump() == "[1,2,3]");
-        CHECK(j3[0].is_number_integer());
-
-        const Json j4 = true;
-        CHECK(j4.is_boolean());
-    }
-
-    SECTION("value_t::number_unsigned creates a number_integer")
-    {
-        const Json j(nlohmann::detail::value_t::number_unsigned);
-        CHECK(j.is_number_integer());
-        CHECK(!j.is_number_unsigned());
-        CHECK(j == 0);
-        CHECK(j.dump() == "0");
-    }
-
-    SECTION("conversions")
-    {
-        Json j = 42;
-        CHECK(j.template get<unsigned>() == 42u);
-        CHECK(j.template get<std::uint64_t>() == 42u);
-        CHECK(j.template get<int>() == 42);
-        CHECK(j.template get<double>() == 42.0);
-        CHECK(j.template get_ptr<integer_t*>() != nullptr);
-        CHECK(*j.template get_ptr<integer_t*>() == 42);
-        CHECK(j.template get_ref<integer_t&>() == 42);
-        j.template get_ref<integer_t&>() = 43;
-        CHECK(j == 43);
-
-        integer_t i = 0;
-        j.get_to(i);
-        CHECK(i == 43);
-
-        const Json object = {{"a", 1}};
-        CHECK(object.value("a", 0u) == 1u);
-        CHECK(object.value("b", 7u) == 7u);
-    }
-
-    SECTION("conversion from a basic_json with distinct types")
-    {
-        const nlohmann::json j = {1, 2u, -3, 4.5};
-        CHECK(j[1].is_number_unsigned());
-        const Json converted = j;
-        CHECK(converted.dump() == "[1,2,-3,4.5]");
-        CHECK(converted[1].is_number_integer());
-        CHECK(!converted[1].is_number_unsigned());
-
-        const nlohmann::json back = converted;
-        CHECK(back == j);
-    }
-
-    SECTION("comparison and hashing")
-    {
-        const Json j1 = 1;
-        const Json j2 = 2u;
-        CHECK(j1 < j2);
-        CHECK(j1 != j2);
-        CHECK(j2 == 2);
-        CHECK(j2 == 2u);
-        CHECK(j1 < 1.5);
-        CHECK(Json(-1) < Json(0u));
-        CHECK(std::hash<Json> {}(Json(5u)) == std::hash<Json> {}(Json(5)));
-    }
-
-    SECTION("JSON Patch, diff, and flatten")
-    {
-        const Json source = Json::parse(R"({"a": [1, 2, 3], "b": 4})");
-        const Json target = Json::parse(R"({"a": [1, 5], "c": 6})");
-        CHECK(source.patch(Json::diff(source, target)) == target);
-        CHECK(source.flatten().unflatten() == source);
-    }
-
-    SECTION("binary formats")
-    {
-        const Json j = {{"min", limits::min()}, {"max", limits::max()}, {"zero", 0}, {"small", 100}, {"negative", -100}, {"float", 1.5}};
-
-        CHECK(Json::from_cbor(Json::to_cbor(j)) == j);
-        CHECK(Json::from_msgpack(Json::to_msgpack(j)) == j);
-        CHECK(Json::from_ubjson(Json::to_ubjson(j)) == j);
-        CHECK(Json::from_bjdata(Json::to_bjdata(j)) == j);
-        CHECK(Json::from_bson(Json::to_bson(j)) == j);
-        CHECK(Json::from_bon8(Json::to_bon8(j)) == j);
-
-        for (const auto& element : Json::from_cbor(Json::to_cbor(j)))
-        {
-            CHECK(!element.is_number_unsigned());
-        }
-
-        // CBOR unsigned integer 2^64-1 does not fit and is read as float
-        const std::vector<std::uint8_t> cbor_max = {0x1B, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
-        const Json from_cbor = Json::from_cbor(cbor_max);
-        CHECK(from_cbor.is_number_float());
-        CHECK(from_cbor.template get<double>() == 18446744073709551615.0);
-
-        // MessagePack uint 8 is read as number_integer
-        const std::vector<std::uint8_t> msgpack_uint8 = {0xCC, 0xC8};
-        const Json from_msgpack = Json::from_msgpack(msgpack_uint8);
-        CHECK(from_msgpack.is_number_integer());
-        CHECK(from_msgpack == 200);
-    }
-}
-
-TEST_CASE("same type for number_integer_t and number_unsigned_t: type traits")
-{
-    CHECK(std::is_same<nlohmann::detail::number_unsigned_overload_t<json64>, nlohmann::detail::same_as_number_integer_type>::value);
-    CHECK(std::is_same<nlohmann::detail::number_unsigned_overload_t<nlohmann::json>, std::uint64_t>::value);
-    CHECK(nlohmann::detail::is_compatible_number_integer_type<json64, unsigned>::value);
-    CHECK(!nlohmann::detail::is_compatible_number_integer_type<nlohmann::json, unsigned>::value);
-    CHECK(!nlohmann::detail::is_compatible_number_integer_type<json64, bool>::value);
-}