Look up the key only once in the callback parser's key()

Since #5466, key() searched the object for a duplicate key and then looked
the key up again to insert the placeholder. Use a single emplace() instead.
Parsing a 32k-member object with a callback: 10.4 ms -> 7.2 ms (3.12.0: 8.0 ms).

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/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`
 

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/json_sax.hpp

@@ -674,16 +674,19 @@ class json_sax_dom_callback_parser
         if (keep && ref_stack.back())
         {
             auto& obj = *ref_stack.back()->m_data.m_value.object;
-            const auto it = obj.find(val);
-            if (it != obj.end())
+            // a single lookup: insert the placeholder, or find the existing member
+            const auto inserted = obj.emplace(val, discarded);
+            const auto it = inserted.first;
+            if (!inserted.second)
             {
                 // this is a duplicate key (legal in JSON); remember its
                 // current value so it can be restored later if the new
                 // value is rejected by the callback, instead of being
                 // erased together with the discarded placeholder
                 duplicate_key_stash.emplace_back(&(it->second), it->second);
+                it->second = discarded;
             }
-            object_element = &(obj[val] = discarded);
+            object_element = &(it->second);
         }
 
         return true;

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

@@ -221,7 +221,7 @@ 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));
+                write_cbor_head(0x00, j.m_data.m_value.number_unsigned);
                 break;
             }
 
@@ -1601,7 +1601,7 @@ class binary_writer
                 return calc_bson_integer_size(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));
+                return calc_bson_unsigned_size(j.m_data.m_value.number_unsigned);
 
             case value_t::string:
                 return calc_bson_string_size(*j.m_data.m_value.string, j);
@@ -1643,7 +1643,7 @@ class binary_writer
                 return write_bson_integer(name, 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, j.m_data.m_value.number_unsigned);
 
             case value_t::string:
                 return write_bson_string(name, *j.m_data.m_value.string);

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/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

@@ -4687,22 +4687,6 @@ 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 +5024,6 @@ 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 +5776,7 @@ 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 +5846,7 @@ 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 +6102,7 @@ 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 +7250,14 @@ 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 +9087,7 @@ 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 +9497,6 @@ 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 +9530,8 @@ 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;
 }
 
 /*!
@@ -13909,16 +13850,19 @@ class json_sax_dom_callback_parser
         if (keep && ref_stack.back())
         {
             auto& obj = *ref_stack.back()->m_data.m_value.object;
-            const auto it = obj.find(val);
-            if (it != obj.end())
+            // a single lookup: insert the placeholder, or find the existing member
+            const auto inserted = obj.emplace(val, discarded);
+            const auto it = inserted.first;
+            if (!inserted.second)
             {
                 // this is a duplicate key (legal in JSON); remember its
                 // current value so it can be restored later if the new
                 // value is rejected by the callback, instead of being
                 // erased together with the discarded placeholder
                 duplicate_key_stash.emplace_back(&(it->second), it->second);
+                it->second = discarded;
             }
-            object_element = &(obj[val] = discarded);
+            object_element = &(it->second);
         }
 
         return true;
@@ -22617,7 +22561,7 @@ 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));
+                write_cbor_head(0x00, j.m_data.m_value.number_unsigned);
                 break;
             }
 
@@ -23997,7 +23941,7 @@ class binary_writer
                 return calc_bson_integer_size(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));
+                return calc_bson_unsigned_size(j.m_data.m_value.number_unsigned);
 
             case value_t::string:
                 return calc_bson_string_size(*j.m_data.m_value.string, j);
@@ -24039,7 +23983,7 @@ class binary_writer
                 return write_bson_integer(name, 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, j.m_data.m_value.number_unsigned);
 
             case value_t::string:
                 return write_bson_string(name, *j.m_data.m_value.string);
@@ -27458,12 +27402,6 @@ 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 +28580,7 @@ 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 +28763,7 @@ 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 +28776,7 @@ 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 +28944,17 @@ 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 +28964,10 @@ 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 +29851,8 @@ 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 +29926,8 @@ 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 +31532,7 @@ 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 +31613,7 @@ 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 +32198,14 @@ 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-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);
-}