Refactor destroy() for readability and add edge-case tests

Apply review feedback from Greg Marr on the json_value::destroy()
non-recursive, allocation-free destruction walk (#5135):

- last_child() now uses object->rbegin()->second instead of
  std::prev(object->end())->second; pop_last_child() keeps
  std::prev(end()) since erase() needs a forward iterator.
- is_empty_container() becomes has_no_children(), a switch that
  returns true for every non-container type as well as empty
  array/object, simplifying the "scalar or already-empty child"
  check at the call site. The local variable `last` is renamed to
  `cur_last_ref` for clarity.
- free_container() asserts the array/object is already empty before
  freeing it, and the object branches assert the expected type.
- destroy(value_t t) is now a thin dispatcher to destroy_string(),
  destroy_binary(), and destroy_container(t), each handling its own
  "not initialized" check and sharing the simple cases first in the
  switch.
- destroy_container() moves the top-level container into the local
  stand-in via a plain swap of the json_value union, instead of a
  manual copy plus clearing array/object by hand.
- The "cur has no children and there is no parent" case now frees
  cur and returns immediately, so the main loop is a plain
  while (true) with no trailing code after it.

Also adds edge-case tests for both json and ordered_json (mixes of
empty/non-empty arrays and objects, container children in first/last
position, single-element chains, top-level empty containers, and
destruction via erase()/assignment), plus a mixed-tree case in the
"destructor performs no allocation" test.

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

.github/external_ci/appveyor.yml

@@ -16,9 +16,6 @@ only_commits:
 
 environment:
   matrix:
-    # The Visual Studio 2017 jobs compile everything with /std:c++17, so they
-    # only build the C++17 variant of each test, split into two jobs each to
-    # stay below AppVeyor's 60-minute limit per job.
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       configuration: Debug
       platform: x86
@@ -37,13 +34,7 @@ environment:
       configuration: Release
       platform: x86
       CXX_FLAGS: "/permissive- /std:c++17 /utf-8 /W4 /WX"
-      CMAKE_OPTIONS: "-DJSON_TestStandards=17 -DJSON_TestShard=0/2"
+      CMAKE_OPTIONS: ""
-      GENERATOR: Visual Studio 15 2017
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-      configuration: Release
-      platform: x86
-      CXX_FLAGS: "/permissive- /std:c++17 /utf-8 /W4 /WX"
-      CMAKE_OPTIONS: "-DJSON_TestStandards=17 -DJSON_TestShard=1/2"
       GENERATOR: Visual Studio 15 2017
 
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
@@ -64,13 +55,7 @@ environment:
       configuration: Release
       platform: x64
       CXX_FLAGS: "/permissive- /std:c++17 /Zc:__cplusplus /utf-8 /W4 /WX"
-      CMAKE_OPTIONS: "-DJSON_TestStandards=17 -DJSON_TestShard=0/2"
+      CMAKE_OPTIONS: ""
-      GENERATOR: Visual Studio 15 2017
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-      configuration: Release
-      platform: x64
-      CXX_FLAGS: "/permissive- /std:c++17 /Zc:__cplusplus /utf-8 /W4 /WX"
-      CMAKE_OPTIONS: "-DJSON_TestStandards=17 -DJSON_TestShard=1/2"
       GENERATOR: Visual Studio 15 2017
 
 init:
@@ -81,7 +66,7 @@ install:
   - if "%platform%"=="x86"    set GENERATOR_PLATFORM=Win32
 
 before_build:
-  - cmake . -G "%GENERATOR%" -A "%GENERATOR_PLATFORM%" -DCMAKE_CXX_FLAGS="%CXX_FLAGS%" -DCMAKE_IGNORE_PATH="C:/Program Files/Git/usr/bin" -DJSON_BuildTests=On %CMAKE_OPTIONS%
+  - cmake . -G "%GENERATOR%" -A "%GENERATOR_PLATFORM%" -DCMAKE_CXX_FLAGS="%CXX_FLAGS%" -DCMAKE_IGNORE_PATH="C:/Program Files/Git/usr/bin" -DJSON_BuildTests=On "%CMAKE_OPTIONS%"
 
 build_script:
   - cmake --build . --config "%configuration%" --parallel 2

.github/workflows/ubuntu.yml

@@ -107,7 +107,7 @@ jobs:
     container: ubuntu:24.04
     strategy:
       matrix:
-        target: [ci_cmake_flags, ci_test_diagnostics, ci_test_diagnostic_positions, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison, ci_test_noglobaludls, ci_test_disableenumserialization, ci_test_disabletuplereferenceconversion, ci_test_skiplibraryversioncheck, ci_test_simdutf, ci_test_strict_nul_handling, ci_test_delete_deprecated_functions, ci_test_no_thread_local]
+        target: [ci_cmake_flags, ci_test_diagnostics, ci_test_diagnostic_positions, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison, ci_test_noglobaludls, ci_test_disableenumserialization, ci_test_disabletuplereferenceconversion, ci_test_skiplibraryversioncheck, ci_test_simdutf, ci_test_strict_nul_handling, ci_test_no_thread_local]
     steps:
       - name: Install build-essential
         run: apt-get update ; apt-get install -y build-essential unzip wget git

CMakeLists.txt

@@ -62,7 +62,6 @@ option(JSON_MultipleHeaders                "Use non-amalgamated version of the l
 option(JSON_SystemInclude                  "Include as system headers (skip for clang-tidy)." OFF)
 option(JSON_StrictNulHandling              "Build with strict NUL-byte handling enabled." OFF)
 option(JSON_StrictBinaryUTF8               "Build with UTF-8 checks in the CBOR, UBJSON, BJData, and BSON writers enabled." OFF)
-option(JSON_DeleteDeprecatedFunctions      "Delete the deprecated functions instead of only deprecating them." OFF)
 
 if (JSON_CI)
     include(ci)
@@ -124,10 +123,6 @@ if (JSON_StrictBinaryUTF8)
     message(STATUS "Strict UTF-8 checks in binary writers enabled (JSON_STRICT_BINARY_UTF8=1)")
 endif()
 
-if (JSON_DeleteDeprecatedFunctions)
-    message(STATUS "Deprecated functions are deleted (JSON_DELETE_DEPRECATED_FUNCTIONS=1)")
-endif()
-
 if (JSON_Diagnostic_Positions)
     message(STATUS "Diagnostic positions enabled (JSON_DIAGNOSTIC_POSITIONS=1)")
 endif()
@@ -164,7 +159,6 @@ target_compile_definitions(
     $<$<BOOL:${JSON_LegacyDiscardedValueComparison}>:JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1>
     $<$<BOOL:${JSON_StrictNulHandling}>:JSON_STRICT_NUL_HANDLING=1>
     $<$<BOOL:${JSON_StrictBinaryUTF8}>:JSON_STRICT_BINARY_UTF8=1>
-    $<$<BOOL:${JSON_DeleteDeprecatedFunctions}>:JSON_DELETE_DEPRECATED_FUNCTIONS=1>
 )
 
 target_include_directories(

cmake/ci.cmake

@@ -249,20 +249,6 @@ add_custom_target(ci_test_strict_nul_handling
     COMMENT "Compile and test with strict NUL-byte handling enabled"
 )
 
-###############################################################################
-# Delete the deprecated functions.
-###############################################################################
-
-add_custom_target(ci_test_delete_deprecated_functions
-    COMMAND ${CMAKE_COMMAND}
-    -DCMAKE_BUILD_TYPE=Debug -GNinja
-    -DJSON_BuildTests=ON -DJSON_FastTests=ON -DJSON_DeleteDeprecatedFunctions=ON
-    -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_delete_deprecated_functions
-    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_delete_deprecated_functions
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_delete_deprecated_functions && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
-    COMMENT "Compile and test with the deprecated functions deleted"
-)
-
 ###############################################################################
 # Disable global UDLs.
 ###############################################################################
@@ -376,7 +362,7 @@ add_custom_target(ci_test_coverage
 # Sanitizers.
 ###############################################################################
 
-set(CLANG_CXX_FLAGS_SANITIZER "-g -O1 -fsanitize=address -fsanitize=undefined -fsanitize=integer -fsanitize=nullability -fno-omit-frame-pointer -fno-sanitize-recover=all -fno-sanitize=unsigned-integer-overflow -fno-sanitize=unsigned-shift-base -fsanitize-ignorelist=${PROJECT_SOURCE_DIR}/cmake/clang_sanitizer_ignorelist.txt")
+set(CLANG_CXX_FLAGS_SANITIZER "-g -O1 -fsanitize=address -fsanitize=undefined -fsanitize=integer -fsanitize=nullability -fno-omit-frame-pointer -fno-sanitize-recover=all -fno-sanitize=unsigned-integer-overflow -fno-sanitize=unsigned-shift-base")
 
 add_custom_target(ci_test_clang_sanitizer
     COMMAND CXX=${CLANG_TOOL} CXXFLAGS=${CLANG_CXX_FLAGS_SANITIZER} ${CMAKE_COMMAND}
@@ -719,7 +705,7 @@ ci_get_cmake(4.0.0  CMAKE_4_0_0_BINARY)
 # the tests require CMake 3.13 or later, so they are excluded for CMake 3.5.0
 set(JSON_CMAKE_FLAGS_3_5_0 JSON_Diagnostics JSON_Diagnostic_Positions JSON_GlobalUDLs JSON_ImplicitConversions JSON_DisableEnumSerialization
     JSON_LegacyDiscardedValueComparison JSON_Install JSON_MultipleHeaders JSON_SystemInclude JSON_Valgrind
-    JSON_StrictNulHandling JSON_StrictBinaryUTF8 JSON_DeleteDeprecatedFunctions)
+    JSON_StrictNulHandling JSON_StrictBinaryUTF8)
 set(JSON_CMAKE_FLAGS_3_31_6 JSON_BuildTests ${JSON_CMAKE_FLAGS_3_5_0})
 set(JSON_CMAKE_FLAGS_4_0_0 JSON_BuildTests ${JSON_CMAKE_FLAGS_3_5_0})
 

cmake/clang_sanitizer_ignorelist.txt

@@ -1,8 +0,0 @@
-# Sanitizer ignore list for ci_test_clang_sanitizer (-fsanitize-ignorelist).
-#
-# libstdc++ 14's <format> declares `_Scanner(basic_string_view<_CharT>, size_t __nargs = -1)`, so every std::format
-# call converts -1 to size_t, which -fsanitize=integer reports as implicit-integer-sign-change. This is
-# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119429, not a bug in this library. Only that check and only <format> are
-# excluded, so implicit sign changes in the library and the tests are still reported.
-[implicit-integer-sign-change]
-src:*/include/c++/*/format

docs/docset/docSet.sql

@@ -219,7 +219,6 @@ INSERT INTO searchIndex(name, type, path) VALUES ('Supported Macros', 'Guide', '
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_ASSERT', 'Macro', 'api/macros/json_assert/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_BRACE_INIT_COPY_SEMANTICS', 'Macro', 'api/macros/json_brace_init_copy_semantics/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_CATCH_USER', 'Macro', 'api/macros/json_throw_user/index.html');
-INSERT INTO searchIndex(name, type, path) VALUES ('JSON_DELETE_DEPRECATED_FUNCTIONS', 'Macro', 'api/macros/json_delete_deprecated_functions/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_DIAGNOSTICS', 'Macro', 'api/macros/json_diagnostics/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_DIAGNOSTIC_POSITIONS', 'Macro', 'api/macros/json_diagnostic_positions/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_DISABLE_ENUM_SERIALIZATION', 'Macro', 'api/macros/json_disable_enum_serialization/index.html');
@@ -250,7 +249,6 @@ INSERT INTO searchIndex(name, type, path) VALUES ('JSON_TRY_USER', 'Macro', 'api
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_USE_GLOBAL_UDLS', 'Macro', 'api/macros/json_use_global_udls/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_USE_IMPLICIT_CONVERSIONS', 'Macro', 'api/macros/json_use_implicit_conversions/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON', 'Macro', 'api/macros/json_use_legacy_discarded_value_comparison/index.html');
-INSERT INTO searchIndex(name, type, path) VALUES ('JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS', 'Macro', 'api/macros/json_use_objects_for_enum_keyed_maps/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_USE_SIMDUTF', 'Macro', 'api/macros/json_use_simdutf/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('Macros', 'Macro', 'api/macros/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('NLOHMANN_DEFINE_DERIVED_TYPE_INTRUSIVE', 'Macro', 'api/macros/nlohmann_define_derived_type/index.html');

docs/mkdocs/docs/api/basic_json/diff.md

@@ -8,7 +8,7 @@ static basic_json diff(const basic_json& source,
 Creates a [JSON Patch](http://jsonpatch.com) so that value `source` can be changed into the value `target` by calling
 [`patch`](patch.md) function.
 
-For two JSON values `source` and `target`, the following code always yields `#!cpp true`:
+For two JSON values `source` and `target`, the following code yields always `#!cpp true`:
 ```cpp
 source.patch(diff(source, target)) == target;
 ```
@@ -27,7 +27,7 @@ a JSON patch to convert the `source` to `target`
 
 ## Exception safety
 
-Strong guarantee: `source` and `target` are never modified.
+Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
 
 ## Complexity
 

docs/mkdocs/docs/api/basic_json/from_bjdata.md

@@ -120,12 +120,3 @@ Linear in the size of the input.
 - Extended container support (1) to include types with lvalue-only ADL `begin`/`end` (matching `std::begin`/`std::end` semantics) in version 3.13.0.
 - Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
 - Added `error_handler` parameter in version 3.13.0.
-
-!!! warning "Deprecation"
-
-    - Overload (2) replaces calls to `from_bjdata` with a pointer and a length as first two parameters, which has been
-      deprecated in version 3.13.0. This overload will be removed in version 4.0.0. Please replace all calls like
-      `#!cpp from_bjdata(ptr, len, ...);` with `#!cpp from_bjdata(ptr, ptr+len, ...);`.
-
-    You should be warned by your compiler with a `-Wdeprecated-declarations` warning if you are using a deprecated
-    function.

docs/mkdocs/docs/api/basic_json/from_bon8.md

@@ -106,12 +106,3 @@ Linear in the size of the input.
 ## Version history
 
 - Added in version 3.13.0.
-
-!!! warning "Deprecation"
-
-    - Overload (2) replaces calls to `from_bon8` with a pointer and a length as first two parameters, which has been
-      deprecated in version 3.13.0. This overload will be removed in version 4.0.0. Please replace all calls like
-      `#!cpp from_bon8(ptr, len, ...);` with `#!cpp from_bon8(ptr, ptr+len, ...);`.
-
-    You should be warned by your compiler with a `-Wdeprecated-declarations` warning if you are using a deprecated
-    function.

docs/mkdocs/docs/api/macros/index.md

@@ -61,11 +61,6 @@ header. See also the [macro overview page](../../features/macros.md).
 - [**JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS**](json_use_objects_for_enum_keyed_maps.md) - opt in to storing maps with enum
   keys as objects
 
-## Deprecated functions
-
-- [**JSON_DELETE_DEPRECATED_FUNCTIONS**](json_delete_deprecated_functions.md) - opt in to deleting the deprecated
-  functions ahead of their removal in version 4.0.0
-
 ## Comparison behavior
 
 - [**JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON**](json_use_legacy_discarded_value_comparison.md) -

docs/mkdocs/docs/api/macros/json_delete_deprecated_functions.md

@@ -1,96 +0,0 @@
-# JSON_DELETE_DEPRECATED_FUNCTIONS
-
-```cpp
-#define JSON_DELETE_DEPRECATED_FUNCTIONS /* value */
-```
-
-When defined to `1`, all [deprecated functions](../../community/roadmap.md#removal-of-deprecated-functions) of the
-library are declared as deleted (`= delete`) instead of only being marked as deprecated. Code that still calls one of
-them no longer compiles. This way, you can find all calls that need to be replaced before version 4.0.0 removes these
-functions; the [migration guide](../../integration/migration_guide.md#replace-deprecated-functions) describes how.
-
-A deleted function, unlike a removed one, still takes part in overload resolution. A call that would select it
-therefore fails to compile instead of silently selecting another overload. This matters for the deprecated
-`from_*(ptr, len)` overloads of [`from_cbor`](../basic_json/from_cbor.md), [`from_msgpack`](../basic_json/from_msgpack.md),
-[`from_ubjson`](../basic_json/from_ubjson.md), [`from_bjdata`](../basic_json/from_bjdata.md),
-[`from_bon8`](../basic_json/from_bon8.md), and [`from_bson`](../basic_json/from_bson.md): without them, a call like
-`from_cbor(ptr, len)` would compile, read `ptr` as a NUL-terminated string, and convert `len` to the `strict` parameter.
-
-The macro does not affect the deprecated legacy comparison of discarded values, which is controlled by
-[`JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON`](json_use_legacy_discarded_value_comparison.md).
-
-## Default definition
-
-The default value is `0` (disabled, the deprecated functions can still be called, and the compiler warns about it).
-
-```cpp
-#define JSON_DELETE_DEPRECATED_FUNCTIONS 0
-```
-
-## Notes
-
-!!! info "CMake option"
-
-    The macro can also be set with the CMake option
-    [`JSON_DeleteDeprecatedFunctions`](../../integration/cmake.md#json_deletedeprecatedfunctions) (`OFF` by default).
-
-!!! warning "Opt-in only"
-
-    This macro must be defined **before** including `<nlohmann/json.hpp>`. Defining it after the include has no
-    effect. Define it for the whole project to avoid different declarations of the same class in different
-    translation units.
-
-!!! note "ABI compatibility"
-
-    The macro only turns calls that compile into calls that do not; it does not change the layout or the behavior of
-    any type. Its value is therefore not encoded in the [namespace](../../features/namespace.md).
-
-## Examples
-
-??? example "Example: default behavior (macro not defined)"
-
-    Without the macro, the deprecated overload is called, and the compiler warns about it:
-
-    ```cpp
-    #include <nlohmann/json.hpp>
-
-    using json = nlohmann::json;
-
-    int main()
-    {
-        const std::vector<std::uint8_t> v = {0x82, 0x01, 0x02};
-        auto j = json::from_cbor(v.data(), v.size());
-        // warning: 'from_cbor' is deprecated: Since 3.8.0; use from_cbor(ptr, ptr + len)
-    }
-    ```
-
-??? example "Example: deleted deprecated functions (macro defined to 1)"
-
-    With the macro, the call does not compile:
-
-    ```cpp
-    #define JSON_DELETE_DEPRECATED_FUNCTIONS 1
-    #include <nlohmann/json.hpp>
-
-    using json = nlohmann::json;
-
-    int main()
-    {
-        const std::vector<std::uint8_t> v = {0x82, 0x01, 0x02};
-        auto j = json::from_cbor(v.data(), v.size());
-        // error: call to deleted function 'from_cbor'
-    }
-    ```
-
-## See also
-
-- [Roadmap: removal of deprecated functions](../../community/roadmap.md#removal-of-deprecated-functions) - the
-  deprecated functions and the version they were deprecated in
-- [Migration guide: replace deprecated functions](../../integration/migration_guide.md#replace-deprecated-functions) -
-  how to replace each deprecated function
-
-## Version history
-
-- Added in version 3.13.0.
-- Planned to be removed in version 4.0.0, which removes the deprecated functions. The deprecated `from_*(ptr, len)`
-  overloads stay deleted in version 4.0.0.

docs/mkdocs/docs/api/macros/json_disable_tuple_reference_conversion.md

@@ -112,4 +112,3 @@ The default value is `0` (disabled — existing behavior is preserved).
 ## Version history
 
 - Added in version 3.13.0.
-- Planned to become the default (with the macro removed) in version 4.0.0.

docs/mkdocs/docs/api/macros/json_use_implicit_conversions.md

@@ -44,7 +44,7 @@ By default, implicit conversions are enabled.
 
 ## Examples
 
-??? example "Example: implicit and explicit conversions"
+??? example "Example: implicit conversion"
 
     This is an example for an implicit conversion:
 

docs/mkdocs/docs/api/macros/json_use_objects_for_enum_keyed_maps.md

@@ -69,7 +69,7 @@ The default value is `0` (disabled — existing behavior is preserved).
 
 ## Examples
 
-??? example "Example: default behavior (macro not defined)"
+??? example "Default behavior (macro not defined)"
 
     Without the macro, a map with enum keys is stored as an array of pairs:
 
@@ -96,7 +96,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     }
     ```
 
-??? example "Example: objects for enum-keyed maps (macro defined to 1)"
+??? example "Objects for enum-keyed maps (macro defined to 1)"
 
     With the macro, the same map is stored as an object:
 

docs/mkdocs/docs/community/roadmap.md

@@ -64,8 +64,6 @@ The following macros guard changes that are planned to become the default in ver
 | [`JSON_PRECISE_STREAM_POSITION`](../api/macros/json_precise_stream_position.md)                                  | `0`         | `1`: reading from a stream does not consume the character after a number                                                      | –                                                                                                                  | 3.13.0 |
 | [`JSON_STRICT_NUL_HANDLING`](../api/macros/json_strict_nul_handling.md)                                          | `0`         | `1`: a NUL byte in the input is a parse error instead of the end of input                                                     | [`JSON_StrictNulHandling`](../integration/cmake.md#json_strictnulhandling)                                         | 3.13.0 |
 | [`JSON_STRICT_BINARY_UTF8`](../api/macros/json_strict_binary_utf8.md)                                            | `0`         | `1`: `to_cbor`, `to_ubjson`, `to_bjdata`, and `to_bson` throw for strings that are not valid UTF-8 by default                 | [`JSON_StrictBinaryUTF8`](../integration/cmake.md#json_strictbinaryutf8)                                           | 3.13.0 |
-| [`JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`](../api/macros/json_disable_tuple_reference_conversion.md)            | `0`         | `1`: a `basic_json` value can no longer be created from a one-element tuple of a reference to it, such as `std::forward_as_tuple(j)`| [`JSON_DisableTupleReferenceConversion`](../integration/cmake.md#json_disabletuplereferenceconversion)             | 3.13.0 |
-| [`JSON_DELETE_DEPRECATED_FUNCTIONS`](../api/macros/json_delete_deprecated_functions.md)                          | `0`         | removed: the deprecated functions are removed (see below); the `from_*(ptr, len)` overloads stay deleted                      | [`JSON_DeleteDeprecatedFunctions`](../integration/cmake.md#json_deletedeprecatedfunctions)                         | 3.13.0 |
 
 For example, the following makes a 3.x release behave like version 4.0 with respect to these changes:
 
@@ -77,8 +75,6 @@ For example, the following makes a 3.x release behave like version 4.0 with resp
 #define JSON_PRECISE_STREAM_POSITION 1
 #define JSON_STRICT_NUL_HANDLING 1
 #define JSON_STRICT_BINARY_UTF8 1
-#define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 1
-#define JSON_DELETE_DEPRECATED_FUNCTIONS 1
 #include <nlohmann/json.hpp>
 ```
 
@@ -88,13 +84,8 @@ way to achieve this.
 ### Removal of deprecated functions
 
 Version 4.0 will remove all deprecated functions. Compiling with deprecation warnings enabled shows which of them your
-code still uses. Defining [`JSON_DELETE_DEPRECATED_FUNCTIONS`](../api/macros/json_delete_deprecated_functions.md) to
+code still uses. The [migration guide](../integration/migration_guide.md#replace-deprecated-functions) shows how to
-`1` turns these warnings into errors, as the deprecated functions are then deleted. The
+replace each of them.
-[migration guide](../integration/migration_guide.md#replace-deprecated-functions) shows how to replace each of them.
-
-The `from_*` overloads taking a pointer and a length are not removed in version 4.0, but stay deleted. Without them, a
-call like `from_cbor(ptr, len)` would still compile: it would read `ptr` as a NUL-terminated string and convert `len`
-to the `strict` parameter.
 
 | Deprecated                                                                                                                                                                                                                                         | Since  | Migration                                                                        |
 |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|----------------------------------------------------------------------------------|
@@ -106,7 +97,6 @@ to the `strict` parameter.
 | [`json_pointer::operator string_t`](../api/json_pointer/operator_string_t.md)                                                                                                                                                                      | 3.11.0 | [JSON Pointers](../integration/migration_guide.md#json-pointers)                 |
 | [`json_pointer`](../api/json_pointer/index.md) with a `basic_json` type as template argument, and the overloads of `value`, `contains`, `operator[]`, and `at` accepting such a pointer                                                           | 3.11.0 | [JSON Pointers](../integration/migration_guide.md#json-pointers)                 |
 | Comparing a [`json_pointer`](../api/json_pointer/index.md) with a string via [`operator==`](../api/json_pointer/operator_eq.md) or [`operator!=`](../api/json_pointer/operator_ne.md)                                                              | 3.11.2 | [JSON Pointers](../integration/migration_guide.md#json-pointers)                 |
-| [`from_bjdata`](../api/basic_json/from_bjdata.md) and [`from_bon8`](../api/basic_json/from_bon8.md) with `(ptr, len)`                                                                                                                              | 3.13.0 | [Parsing](../integration/migration_guide.md#parsing)                             |
 
 The deprecated legacy comparison of discarded values is controlled by a macro and therefore listed in the table above.
 

docs/mkdocs/docs/features/macros.md

@@ -23,17 +23,6 @@ This macro overrides [`#!cpp catch`](https://en.cppreference.com/w/cpp/language/
 
 See [full documentation of `JSON_CATCH_USER(exception)`](../api/macros/json_throw_user.md).
 
-## `JSON_DELETE_DEPRECATED_FUNCTIONS`
-
-When defined to `1`, all deprecated functions are declared as deleted instead of only being marked as deprecated, so
-code that still calls them no longer compiles. This way, you can find all calls that need to be replaced before version
-4.0.0 removes these functions.
-
-The macro can also be set with the CMake option
-[`JSON_DeleteDeprecatedFunctions`](../integration/cmake.md#json_deletedeprecatedfunctions) (`OFF` by default).
-
-See [full documentation of `JSON_DELETE_DEPRECATED_FUNCTIONS`](../api/macros/json_delete_deprecated_functions.md).
-
 ## `JSON_DIAGNOSTICS`
 
 This macro enables extended diagnostics for exception messages. Possible values are `1` to enable or `0` to disable
@@ -97,8 +86,7 @@ See [full documentation of `JSON_DISABLE_ENUM_SERIALIZATION`](../api/macros/json
 ## `JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`
 
 When defined to `1`, a JSON value can no longer be created from a one-element `std::tuple` holding a reference to a JSON
-value, such as the result of `std::forward_as_tuple(j)`. This lets `std::tuple` convert such tuples element-wise. This
+value, such as the result of `std::forward_as_tuple(j)`. This lets `std::tuple` convert such tuples element-wise.
-is planned to become the default in version 4.0.0.
 
 See [full documentation of `JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`](../api/macros/json_disable_tuple_reference_conversion.md).
 

docs/mkdocs/docs/integration/cmake.md

@@ -132,12 +132,6 @@ Build the unit tests when [`BUILD_TESTING`](https://cmake.org/cmake/help/latest/
 
 Enable CI build targets. The exact targets are used during the several CI steps and are subject to change without notice. This option is `OFF` by default.
 
-### `JSON_DeleteDeprecatedFunctions`
-
-Delete the deprecated functions instead of only deprecating them by defining the macro
-[`JSON_DELETE_DEPRECATED_FUNCTIONS`](../api/macros/json_delete_deprecated_functions.md). This option is `OFF` by
-default.
-
 ### `JSON_Diagnostics`
 
 Enable [extended diagnostic messages](../home/exceptions.md#extended-diagnostic-messages) by defining macro [`JSON_DIAGNOSTICS`](../api/macros/json_diagnostics.md). This option is `OFF` by default.

docs/mkdocs/docs/integration/migration_guide.md

@@ -14,13 +14,6 @@ deprecations are annotated with
 [`HEDLEY_DEPRECATED_FOR`](https://nemequ.github.io/hedley/api-reference.html#HEDLEY_DEPRECATED_FOR) to report which
 function to use instead.
 
-!!! tip "Find all calls of deprecated functions"
-
-    Define [`JSON_DELETE_DEPRECATED_FUNCTIONS`](../api/macros/json_delete_deprecated_functions.md) to `1` (or set the
-    CMake option [`JSON_DeleteDeprecatedFunctions`](cmake.md#json_deletedeprecatedfunctions)) to delete all deprecated
-    functions. Every remaining call then fails to compile, even if deprecation warnings are disabled, so your code is
-    ready for version 4.0.0 once it compiles with the macro.
-
 ### Parsing
 
 - Function `friend std::istream& operator<<(basic_json&, std::istream&)` is deprecated since 3.0.0. Please use
@@ -48,10 +41,8 @@ function to use instead.
   [`from_ubjson`](../api/basic_json/from_ubjson.md), and [`from_bson`](../api/basic_json/from_bson.md)) via initializer
   lists is deprecated since 3.8.0. Instead, pass two iterators; for instance, call `from_cbor(ptr, ptr+len)` instead of
   `from_cbor({ptr, len})`. Likewise, passing a pointer and a length as two separate arguments to `from_cbor`,
-  `from_msgpack`, `from_ubjson`, and `from_bson` is deprecated since 3.8.0, and to
+  `from_msgpack`, `from_ubjson`, and `from_bson` is deprecated since 3.8.0; call `from_cbor(ptr, ptr+len)` instead of
-  [`from_bjdata`](../api/basic_json/from_bjdata.md) and [`from_bon8`](../api/basic_json/from_bon8.md) since 3.13.0; call
+  `from_cbor(ptr, len)`.
-  `from_cbor(ptr, ptr+len)` instead of `from_cbor(ptr, len)`. These overloads will not be removed in version 4.0.0, but
-  deleted, so a call like `from_cbor(ptr, len)` cannot compile and convert `len` to the `strict` parameter.
 
     === "Deprecated"
   

docs/mkdocs/mkdocs.yml

@@ -292,7 +292,6 @@ nav:
           - 'JSON_BRACE_INIT_COPY_SEMANTICS': api/macros/json_brace_init_copy_semantics.md
           - 'JSON_CATCH_USER, JSON_THROW_USER, JSON_TRY_USER': api/macros/json_throw_user.md
           - 'JSON_DIAGNOSTICS': api/macros/json_diagnostics.md
-          - 'JSON_DELETE_DEPRECATED_FUNCTIONS': api/macros/json_delete_deprecated_functions.md
           - 'JSON_DIAGNOSTIC_POSITIONS': api/macros/json_diagnostic_positions.md
           - 'JSON_DISABLE_ENUM_SERIALIZATION': api/macros/json_disable_enum_serialization.md
           - 'JSON_DISABLE_TUPLE_REFERENCE_CONVERSION': api/macros/json_disable_tuple_reference_conversion.md

include/nlohmann/detail/conversions/from_json.hpp

@@ -172,7 +172,7 @@ inline void from_json(const BasicJsonType& j, EnumType& e)
           typename BasicJsonType::number_unsigned_t, underlying_type>::type;
     value_type val;
     get_arithmetic_value(j, val);
-    e = static_cast<EnumType>(bool_aware_static_cast<underlying_type>(val));
+    e = static_cast<EnumType>(static_cast<underlying_type>(val));
 }
 #endif  // JSON_DISABLE_ENUM_SERIALIZATION
 

include/nlohmann/detail/conversions/to_json.hpp

@@ -287,20 +287,9 @@ struct external_constructor<value_t::object>
 /////////////
 
 #ifdef JSON_HAS_CPP_17
-// whether storing the value of a std::optional<T> cannot throw; MSVC 2017
-// evaluates std::is_nothrow_assignable as true even if T's to_json throws, so
-// the exception would call std::terminate (#5642)
-#if defined(_MSC_VER) && !defined(__clang__) && _MSC_VER < 1920
-    template<typename BasicJsonType, typename T>
-    using is_nothrow_optional_to_json = std::false_type;
-#else
-    template<typename BasicJsonType, typename T>
-    using is_nothrow_optional_to_json = std::is_nothrow_assignable<BasicJsonType&, const T&>;
-#endif
-
 template<typename BasicJsonType, typename T,
          enable_if_t<std::is_constructible<BasicJsonType, T>::value, int> = 0>
-void to_json(BasicJsonType& j, const std::optional<T>& opt) noexcept(is_nothrow_optional_to_json<BasicJsonType, T>::value)
+void to_json(BasicJsonType& j, const std::optional<T>& opt) noexcept(std::is_nothrow_assignable<BasicJsonType&, const T&>::value)
 {
     if (opt.has_value())
     {
@@ -376,7 +365,7 @@ inline void to_json(BasicJsonType& j, EnumType e) noexcept
 {
     using underlying_type = typename std::underlying_type<EnumType>::type;
     static constexpr value_t integral_value_t = std::is_unsigned<underlying_type>::value ? value_t::number_unsigned : value_t::number_integer;
-    external_constructor<integral_value_t>::construct(j, bool_aware_static_cast<underlying_type>(e));
+    external_constructor<integral_value_t>::construct(j, static_cast<underlying_type>(e));
 }
 #endif  // JSON_DISABLE_ENUM_SERIALIZATION
 

include/nlohmann/detail/input/binary_reader.hpp

@@ -662,11 +662,10 @@ class binary_reader
         }
 
         // the value is -1 - number, which fits into number_integer_t
-        // whenever number does; the outer cast undoes the integral promotion
+        // whenever number does
-        // for number_integer_t types narrower than int
         if (JSON_HEDLEY_LIKELY(value_in_range_of<number_integer_t>(number)))
         {
-            return sax->number_integer(conditional_static_cast<number_integer_t>(static_cast<number_integer_t>(-1) - static_cast<number_integer_t>(number)));
+            return sax->number_integer(static_cast<number_integer_t>(-1) - static_cast<number_integer_t>(number));
         }
 
         // like the lexer does for JSON text, store a value too small for
@@ -4004,8 +4003,7 @@ class binary_reader
         {
             return sax->number_unsigned(static_cast<number_unsigned_t>(number));
         }
-        // std::isfinite has no integer overloads in MSVC's <cmath>
+        return emit_float(number);
-        return emit_float(static_cast<long double>(number));
     }
 
     /*!
@@ -4028,8 +4026,7 @@ class binary_reader
         {
             return sax->number_unsigned(static_cast<number_unsigned_t>(number));
         }
-        // std::isfinite has no integer overloads in MSVC's <cmath>
+        return emit_float(number);
-        return emit_float(static_cast<long double>(number));
     }
 
     /*!
@@ -4040,8 +4037,7 @@ class binary_reader
     and NaN in the input are passed on unchanged. Integers only overflow if
     number_float_t cannot represent 2^64, e.g., a half-precision type.
 
-    @tparam NumberType a floating-point type (emit_signed and emit_unsigned
+    @tparam NumberType a floating-point or integer type
-                       convert integers to long double first)
     @param[in] number  the number
     @return whether the SAX parser accepted the value
 

include/nlohmann/detail/json_pointer.hpp

@@ -81,13 +81,9 @@ class json_pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/operator_string_t/
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, to_string())
     operator string_t() const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return to_string();
     }
-#endif
 
 #ifndef JSON_NO_IO
     /// @brief write string representation of the JSON pointer to stream
@@ -1026,13 +1022,9 @@ class json_pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/operator_eq/
     JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator==(json_pointer))
     bool operator==(const string_t& rhs) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return *this == json_pointer(rhs);
     }
-#endif
 
     /// @brief 3-way compares two JSON pointers
     template<typename RefStringTypeRhs>
@@ -1110,26 +1102,18 @@ template<typename RefStringTypeLhs,
 JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator==(json_pointer, json_pointer))
 inline bool operator==(const json_pointer<RefStringTypeLhs>& lhs,
                        const StringType& rhs)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
 {
     return lhs == json_pointer<RefStringTypeLhs>(rhs);
 }
-#endif
 
 template<typename RefStringTypeRhs,
          typename StringType = typename json_pointer<RefStringTypeRhs>::string_t>
 JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator==(json_pointer, json_pointer))
 inline bool operator==(const StringType& lhs,
                        const json_pointer<RefStringTypeRhs>& rhs)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
 {
     return json_pointer<RefStringTypeRhs>(lhs) == rhs;
 }
-#endif
 
 template<typename RefStringTypeLhs, typename RefStringTypeRhs>
 inline bool operator!=(const json_pointer<RefStringTypeLhs>& lhs,
@@ -1143,26 +1127,18 @@ template<typename RefStringTypeLhs,
 JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator!=(json_pointer, json_pointer))
 inline bool operator!=(const json_pointer<RefStringTypeLhs>& lhs,
                        const StringType& rhs)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
 {
     return !(lhs == rhs);
 }
-#endif
 
 template<typename RefStringTypeRhs,
          typename StringType = typename json_pointer<RefStringTypeRhs>::string_t>
 JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator!=(json_pointer, json_pointer))
 inline bool operator!=(const StringType& lhs,
                        const json_pointer<RefStringTypeRhs>& rhs)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
 {
     return !(lhs == rhs);
 }
-#endif
 
 template<typename RefStringTypeLhs, typename RefStringTypeRhs>
 inline bool operator<(const json_pointer<RefStringTypeLhs>& lhs,

include/nlohmann/detail/macro_scope.hpp

@@ -888,10 +888,6 @@
     #define JSON_DISABLE_ENUM_SERIALIZATION 0
 #endif
 
-#ifndef JSON_DELETE_DEPRECATED_FUNCTIONS
-    #define JSON_DELETE_DEPRECATED_FUNCTIONS 0
-#endif
-
 #ifndef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
     #define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 0
 #endif

include/nlohmann/detail/macro_unscope.hpp

@@ -43,7 +43,6 @@
     #undef JSON_PRECISE_STREAM_POSITION
     #undef JSON_STRICT_NUL_HANDLING
     #undef JSON_STRICT_BINARY_UTF8
-    #undef JSON_DELETE_DEPRECATED_FUNCTIONS
     #undef JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS
 #endif
 

include/nlohmann/detail/meta/type_traits.hpp

@@ -906,21 +906,6 @@ T conditional_static_cast(U value)
     return value;
 }
 
-// like conditional_static_cast, but converts to bool by comparing with zero,
-// because MSVC 2015 warns about any conversion to bool (C4800), even with an
-// explicit cast; used for enums whose underlying type is bool
-template < typename T, typename U, enable_if_t < !std::is_same<T, bool>::value, int > = 0 >
-T bool_aware_static_cast(U value)
-{
-    return conditional_static_cast<T>(value);
-}
-
-template<typename T, typename U, enable_if_t<std::is_same<T, bool>::value, int> = 0>
-bool bool_aware_static_cast(U value)
-{
-    return value != U();
-}
-
 template<typename... Types>
 using all_integral = conjunction<std::is_integral<Types>...>;
 

include/nlohmann/json.hpp

@@ -612,100 +612,208 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         /// constructor for rvalue binary arrays (internal type)
         json_value(binary_t&& value) : binary(create<binary_t>(std::move(value))) {}
 
-        void destroy(value_t t)
+        // raw, allocation-free transfer of m_data from src to dst: no
+        // set_parents()/assert_invariant() (the former is O(#children) per
+        // call under JSON_DIAGNOSTICS, which would make the walk below
+        // quadratic); dst takes ownership, src is left as value_t::null.
+        static void take(basic_json& dst, basic_json& src) noexcept
+        {
+            dst.m_data.m_type = src.m_data.m_type;
+            dst.m_data.m_value = src.m_data.m_value;
+            src.m_data.m_type = value_t::null;
+        }
+
+        // true if v is not an array/object, or is an already-empty one
+        static bool has_no_children(const basic_json& v) noexcept
+        {
+            switch (v.m_data.m_type)
+            {
+                case value_t::array:
+                    return v.m_data.m_value.array->empty();
+                case value_t::object:
+                    return v.m_data.m_value.object->empty();
+                default:
+                    return true;
+            }
+        }
+
+        static basic_json& last_child(basic_json& v)
+        {
+            if (v.m_data.m_type == value_t::array)
+            {
+                return v.m_data.m_value.array->back();
+            }
+            JSON_ASSERT(v.m_data.m_type == value_t::object);
+            return v.m_data.m_value.object->rbegin()->second;
+        }
+
+        // removes the last child of a non-empty array/object v; this never
+        // allocates, and since it is only ever called when that child is a
+        // scalar or an already-empty array/object, destroying it never
+        // recurses more than one level deep (see destroy() below)
+        static void pop_last_child(basic_json& v)
+        {
+            if (v.m_data.m_type == value_t::array)
+            {
+                v.m_data.m_value.array->pop_back();
+            }
+            else
+            {
+                JSON_ASSERT(v.m_data.m_type == value_t::object);
+                // erase() needs a forward iterator, so std::prev(end()) is
+                // used here rather than rbegin() (see last_child() above)
+                v.m_data.m_value.object->erase(std::prev(v.m_data.m_value.object->end()));
+            }
+        }
+
+        // deallocates the (already empty) array/object held by v; this is
+        // the same allocator-based free the old recursive implementation
+        // used, just factored out so every level of the walk in destroy()
+        // can share it
+        static void free_container(basic_json& v) noexcept
+        {
+            if (v.m_data.m_type == value_t::array)
+            {
+                JSON_ASSERT(v.m_data.m_value.array->empty());
+                AllocatorType<array_t> alloc;
+                std::allocator_traits<decltype(alloc)>::destroy(alloc, v.m_data.m_value.array);
+                std::allocator_traits<decltype(alloc)>::deallocate(alloc, v.m_data.m_value.array, 1);
+            }
+            else
+            {
+                JSON_ASSERT(v.m_data.m_type == value_t::object);
+                JSON_ASSERT(v.m_data.m_value.object->empty());
+                AllocatorType<object_t> alloc;
+                std::allocator_traits<decltype(alloc)>::destroy(alloc, v.m_data.m_value.object);
+                std::allocator_traits<decltype(alloc)>::deallocate(alloc, v.m_data.m_value.object, 1);
+            }
+            v.m_data.m_type = value_t::null; // avoid a double free if v is later destructed
+        }
+
+        void destroy_string() noexcept
+        {
+            if (string == nullptr)
+            {
+                // not initialized (e.g., due to exception in the ctor)
+                return;
+            }
+            AllocatorType<string_t> alloc;
+            std::allocator_traits<decltype(alloc)>::destroy(alloc, string);
+            std::allocator_traits<decltype(alloc)>::deallocate(alloc, string, 1);
+        }
+
+        void destroy_binary() noexcept
+        {
+            if (binary == nullptr)
+            {
+                // not initialized (e.g., due to exception in the ctor)
+                return;
+            }
+            AllocatorType<binary_t> alloc;
+            std::allocator_traits<decltype(alloc)>::destroy(alloc, binary);
+            std::allocator_traits<decltype(alloc)>::deallocate(alloc, binary, 1);
+        }
+
+        // t must be value_t::array or value_t::object
+        void destroy_container(value_t t) noexcept
         {
             if (
                 (t == value_t::object && object == nullptr) ||
-                (t == value_t::array && array == nullptr) ||
+                (t == value_t::array && array == nullptr)
-                (t == value_t::string && string == nullptr) ||
-                (t == value_t::binary && binary == nullptr)
             )
             {
                 // not initialized (e.g., due to exception in the ctor)
                 return;
             }
-            if (t == value_t::array || t == value_t::object)
+
+            // Destroy the tree without recursing per nesting level and
+            // without any heap allocation: a heap-allocated flattening
+            // stack (the previous implementation) can itself throw
+            // bad_alloc, which would escape this noexcept destructor and
+            // terminate the program (#5135).
+            //
+            // Instead, walk down the "last child" chain, reversing links
+            // as we go: cur is the container currently being emptied,
+            // and prev is its parent (value_t::null when there is none).
+            // Each parent's last child slot doubles as storage for that
+            // parent's own parent link while we are below it, so no
+            // extra memory is needed. We only ever remove a child once
+            // it is a scalar or an empty array/object, which neither
+            // allocates nor recurses more than one level deep.
+            //
+            // This json_value is not itself a basic_json, so the
+            // top-level container is first moved into a local stand-in
+            // ("cur"); a default-constructed basic_json has a null
+            // pointer in its m_value (see data::m_value's initializer),
+            // so swapping it with *this leaves this union's own pointer
+            // null, and it is never looked at or freed a second time.
+            basic_json cur;
+            cur.m_data.m_type = t;
+            using std::swap;
+            swap(cur.m_data.m_value, *this);
+
+            basic_json prev; // value_t::null: no parent
+
+            while (true)
             {
-                // flatten the current json_value to a heap-allocated stack
+                if (has_no_children(cur))
-                std::vector<basic_json> stack;
-
-                // move the top-level items to stack
-                if (t == value_t::array)
                 {
-                    stack.reserve(array->size());
+                    if (prev.m_data.m_type == value_t::null)
-                    std::move(array->begin(), array->end(), std::back_inserter(stack));
-                }
-                else
-                {
-                    stack.reserve(object->size());
-                    for (auto&& it : *object)
                     {
-                        stack.push_back(std::move(it.second));
+                        free_container(cur);
-                    }
+                        return; // back at the top with nothing left to do
-                }
-
-                while (!stack.empty())
-                {
-                    // move the last item to a local variable to be processed
-                    basic_json current_item(std::move(stack.back()));
-                    stack.pop_back();
-
-                    // if current_item is array/object, move
-                    // its children to the stack to be processed later
-                    if (current_item.is_array())
-                    {
-                        std::move(current_item.m_data.m_value.array->begin(), current_item.m_data.m_value.array->end(), std::back_inserter(stack));
-
-                        current_item.m_data.m_value.array->clear();
-                    }
-                    else if (current_item.is_object())
-                    {
-                        for (auto&& it : *current_item.m_data.m_value.object)
-                        {
-                            stack.push_back(std::move(it.second));
-                        }
-
-                        current_item.m_data.m_value.object->clear();
                     }
 
-                    // it's now safe that current_item gets destructed
+                    // ascend: detach the grandparent link from prev's
-                    // since it doesn't have any children
+                    // last slot, drop that (now null) slot, free cur
+                    // (it is empty), then move up one level
+                    basic_json gp;
+                    take(gp, last_child(prev));
+                    pop_last_child(prev);
+
+                    free_container(cur);
+
+                    take(cur, prev);
+                    take(prev, gp);
+                    continue;
                 }
+
+                basic_json& cur_last_ref = last_child(cur);
+
+                if (has_no_children(cur_last_ref))
+                {
+                    // scalar, or already-empty array/object
+                    pop_last_child(cur);
+                    continue;
+                }
+
+                // descend into the non-empty last child, reversing the
+                // link: its slot takes over prev, and the child becomes
+                // the new cur
+                basic_json tmp;
+                take(tmp, cur_last_ref);
+                take(cur_last_ref, prev);
+                take(prev, cur);
+                take(cur, tmp);
             }
+        }
 
+        void destroy(value_t t)
+        {
             switch (t)
             {
-                case value_t::object:
-                {
-                    AllocatorType<object_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, object);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, object, 1);
-                    break;
-                }
-
-                case value_t::array:
-                {
-                    AllocatorType<array_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, array);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, array, 1);
-                    break;
-                }
-
                 case value_t::string:
-                {
+                    destroy_string();
-                    AllocatorType<string_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, string);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, string, 1);
                     break;
-                }
 
                 case value_t::binary:
-                {
+                    destroy_binary();
-                    AllocatorType<binary_t> alloc;
+                    break;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, binary);
+
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, binary, 1);
+                case value_t::object:
+                case value_t::array:
+                    destroy_container(t);
                     break;
-                }
 
                 case value_t::null:
                 case value_t::boolean:
@@ -714,9 +822,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                 case value_t::number_float:
                 case value_t::discarded:
                 default:
-                {
                     break;
-                }
             }
         }
     };
@@ -3492,13 +3598,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                    && !std::is_same<value_t, detail::uncvref_t<ValueType>>::value, int > = 0 >
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     ValueType value(const ::nlohmann::json_pointer<BasicJsonType>& ptr, const ValueType& default_value) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return value(ptr.convert(), default_value);
     }
-#endif
 
     template < class ValueType, class BasicJsonType, class ReturnType = typename value_return_type<ValueType>::type,
                detail::enable_if_t <
@@ -3507,13 +3609,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                    && !std::is_same<value_t, detail::uncvref_t<ValueType>>::value, int > = 0 >
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     ReturnType value(const ::nlohmann::json_pointer<BasicJsonType>& ptr, ValueType && default_value) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return value(ptr.convert(), std::forward<ValueType>(default_value));
     }
-#endif
 
     /// @brief access the first element
     /// @sa https://json.nlohmann.me/api/basic_json/front/
@@ -3871,13 +3969,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     bool contains(const typename ::nlohmann::json_pointer<BasicJsonType>& ptr) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.contains(this);
     }
-#endif
 
     /// @}
 
@@ -3988,13 +4082,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     ///             that is, replace `json::iterator_wrapper(j)` with `j.items()`.
     JSON_HEDLEY_DEPRECATED_FOR(3.1.0, items())
     static iteration_proxy<iterator> iterator_wrapper(reference ref) noexcept
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return ref.items();
     }
-#endif
 
     /// @brief wrapper to access iterator member functions in range-based for
     /// @sa https://json.nlohmann.me/api/basic_json/items/
@@ -4003,13 +4093,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     ///         that is, replace `json::iterator_wrapper(j)` with `j.items()`.
     JSON_HEDLEY_DEPRECATED_FOR(3.1.0, items())
     static iteration_proxy<const_iterator> iterator_wrapper(const_reference ref) noexcept
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return ref.items();
     }
-#endif
 
     /// @brief helper to access iterator member functions in range-based for
     /// @sa https://json.nlohmann.me/api/basic_json/items/
@@ -5098,7 +5184,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_le/
     template<typename ScalarType>
     requires std::is_scalar_v<ScalarType>
-    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) <= rhs;
     }
@@ -5107,7 +5193,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ge/
     template<typename ScalarType>
     requires std::is_scalar_v<ScalarType>
-    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) >= rhs;
     }
@@ -5128,16 +5214,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 #endif
     }
 
-    // The friend comparisons with a scalar name the JSON type via decltype of
-    // their parameter in noexcept, because older MSVC versions do not see the
-    // class scope there: MSVC 2015 and 2017 take basic_json as the template,
-    // and MSVC 2019 16.0 rejects member types and template parameters.
-
     /// @brief comparison: equal
     /// @sa https://json.nlohmann.me/api/basic_json/operator_eq/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator==(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator==(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs == basic_json(rhs);
     }
@@ -5146,7 +5227,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_eq/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator==(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator==(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) == rhs;
     }
@@ -5162,7 +5243,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ne/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator!=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator!=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs != basic_json(rhs);
     }
@@ -5171,7 +5252,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ne/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator!=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator!=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) != rhs;
     }
@@ -5191,7 +5272,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_lt/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator<(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs < basic_json(rhs);
     }
@@ -5200,7 +5281,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_lt/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator<(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) < rhs;
     }
@@ -5220,7 +5301,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_le/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator<=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs <= basic_json(rhs);
     }
@@ -5229,7 +5310,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_le/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) <= rhs;
     }
@@ -5250,7 +5331,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_gt/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator>(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs > basic_json(rhs);
     }
@@ -5259,7 +5340,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_gt/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator>(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) > rhs;
     }
@@ -5279,7 +5360,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ge/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator>=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs >= basic_json(rhs);
     }
@@ -5288,7 +5369,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ge/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) >= rhs;
     }
@@ -5324,9 +5405,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return o;
     }
 
-#if !JSON_DELETE_DEPRECATED_FUNCTIONS
-    // the deleted version is a function template after the class, because
-    // GCC < 5 and Clang < 10 reject deleted friend functions in class templates
     /// @brief serialize to stream
     /// @sa https://json.nlohmann.me/api/operator_ltlt/
     /// @deprecated This function is deprecated since 3.0.0 and will be removed in
@@ -5338,7 +5416,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     {
         return o << j;
     }
-#endif
 #endif  // JSON_NO_IO
     /// @}
 
@@ -5390,16 +5467,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                             const bool allow_exceptions = true,
                             const bool ignore_comments = false,
                             const bool ignore_trailing_commas = false)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         basic_json result;
         auto p = parser(i.get(), std::move(cb), allow_exceptions, ignore_comments, ignore_trailing_commas);
         p.parse(true, result);
         return result;
     }
-#endif
 
     /// @brief check if the input is valid JSON
     /// @sa https://json.nlohmann.me/api/basic_json/accept/
@@ -5429,13 +5502,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static bool accept(detail::span_input_adapter&& i,
                        const bool ignore_comments = false,
                        const bool ignore_trailing_commas = false)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return parser(i.get(), nullptr, false, ignore_comments, ignore_trailing_commas, true).accept(true);
     }
-#endif
 
     /// @brief generate SAX events
     /// @sa https://json.nlohmann.me/api/basic_json/sax_parse/
@@ -5496,9 +5565,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                           const bool strict = true,
                           const bool ignore_comments = false,
                           const bool ignore_trailing_commas = false)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         auto ia = i.get();
         return format == input_format_t::json
@@ -5507,14 +5573,10 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
                : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict);
     }
-#endif
 #if defined(__clang__)
 #pragma clang diagnostic pop
 #endif
 #ifndef JSON_NO_IO
-#if !JSON_DELETE_DEPRECATED_FUNCTIONS
-    // the deleted version is a function template after the class, because
-    // GCC < 5 and Clang < 10 reject deleted friend functions in class templates
     /// @brief deserialize from stream
     /// @sa https://json.nlohmann.me/api/operator_gtgt/
     /// @deprecated This stream operator is deprecated since 3.0.0 and will be removed in
@@ -5526,7 +5588,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     {
         return operator>>(i, j);
     }
-#endif
 
     /// @brief deserialize from stream
     /// @sa https://json.nlohmann.me/api/operator_gtgt/
@@ -5874,13 +5935,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                                 const bool strict = true,
                                 const bool allow_exceptions = true,
                                 const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return from_cbor(ptr, ptr + len, strict, allow_exceptions, tag_handler);
     }
-#endif
 
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
@@ -5888,13 +5945,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                                 const bool strict = true,
                                 const bool allow_exceptions = true,
                                 const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return from_binary_impl(i.get(), input_format_t::cbor, strict, allow_exceptions, error_handler_t::keep, tag_handler);
     }
-#endif
 
     /// @brief create a JSON value from an input in MessagePack format
     /// @sa https://json.nlohmann.me/api/basic_json/from_msgpack/
@@ -5927,26 +5980,18 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static basic_json from_msgpack(const T* ptr, std::size_t len,
                                    const bool strict = true,
                                    const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return from_msgpack(ptr, ptr + len, strict, allow_exceptions);
     }
-#endif
 
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
     static basic_json from_msgpack(detail::span_input_adapter&& i,
                                    const bool strict = true,
                                    const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return from_binary_impl(i.get(), input_format_t::msgpack, strict, allow_exceptions);
     }
-#endif
 
     /// @brief create a JSON value from an input in UBJSON format
     /// @sa https://json.nlohmann.me/api/basic_json/from_ubjson/
@@ -5979,26 +6024,18 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static basic_json from_ubjson(const T* ptr, std::size_t len,
                                   const bool strict = true,
                                   const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return from_ubjson(ptr, ptr + len, strict, allow_exceptions);
     }
-#endif
 
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
     static basic_json from_ubjson(detail::span_input_adapter&& i,
                                   const bool strict = true,
                                   const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return from_binary_impl(i.get(), input_format_t::ubjson, strict, allow_exceptions);
     }
-#endif
 
     /// @brief create a JSON value from an input in BJData format
     /// @sa https://json.nlohmann.me/api/basic_json/from_bjdata/
@@ -6025,20 +6062,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return from_binary_impl(detail::input_adapter(std::move(first), std::move(last)), input_format_t::bjdata, strict, allow_exceptions, error_handler);
     }
 
-    template<typename T>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.13.0, from_bjdata(ptr, ptr + len))
-    static basic_json from_bjdata(const T* ptr, std::size_t len,
-                                  const bool strict = true,
-                                  const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
-    {
-        return from_bjdata(ptr, ptr + len, strict, allow_exceptions);
-    }
-#endif
-
     /// @brief create a JSON value from an input in BON8 format
     /// @sa https://json.nlohmann.me/api/basic_json/from_bon8/
     template<typename InputType>
@@ -6062,20 +6085,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return from_binary_impl(detail::input_adapter(std::move(first), std::move(last)), input_format_t::bon8, strict, allow_exceptions);
     }
 
-    template<typename T>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.13.0, from_bon8(ptr, ptr + len))
-    static basic_json from_bon8(const T* ptr, std::size_t len,
-                                const bool strict = true,
-                                const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
-    {
-        return from_bon8(ptr, ptr + len, strict, allow_exceptions);
-    }
-#endif
-
     /// @brief create a JSON value from an input in BSON format
     /// @sa https://json.nlohmann.me/api/basic_json/from_bson/
     template<typename InputType>
@@ -6107,26 +6116,18 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static basic_json from_bson(const T* ptr, std::size_t len,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return from_bson(ptr, ptr + len, strict, allow_exceptions);
     }
-#endif
 
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
     static basic_json from_bson(detail::span_input_adapter&& i,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return from_binary_impl(i.get(), input_format_t::bson, strict, allow_exceptions);
     }
-#endif
     /// @}
 
     //////////////////////////
@@ -6146,13 +6147,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.get_unchecked(this);
     }
-#endif
 
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
@@ -6164,13 +6161,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     const_reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.get_unchecked(this);
     }
-#endif
 
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/at/
@@ -6182,13 +6175,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.get_checked(this);
     }
-#endif
 
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/at/
@@ -6200,13 +6189,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     const_reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.get_checked(this);
     }
-#endif
 
     /// @brief return flattened JSON value
     /// @sa https://json.nlohmann.me/api/basic_json/flatten/
@@ -7183,18 +7168,6 @@ std::string format_as(const NLOHMANN_BASIC_JSON_TPL& j)
     return j.dump();
 }
 
-#if JSON_DELETE_DEPRECATED_FUNCTIONS && !defined(JSON_NO_IO)
-    /// @brief serialize to stream (deleted; use operator<<(std::ostream&, const basic_json&))
-    /// @sa https://json.nlohmann.me/api/operator_ltlt/
-    NLOHMANN_BASIC_JSON_TPL_DECLARATION
-    std::ostream& operator>>(const NLOHMANN_BASIC_JSON_TPL& j, std::ostream& o) = delete;
-
-    /// @brief deserialize from stream (deleted; use operator>>(std::istream&, basic_json&))
-    /// @sa https://json.nlohmann.me/api/operator_gtgt/
-    NLOHMANN_BASIC_JSON_TPL_DECLARATION
-    std::istream& operator<<(NLOHMANN_BASIC_JSON_TPL& j, std::istream& i) = delete;
-#endif
-
 NLOHMANN_JSON_NAMESPACE_END
 
 ///////////////////////

single_include/nlohmann/json.hpp

@@ -3225,10 +3225,6 @@ JSON_HEDLEY_DIAGNOSTIC_POP
     #define JSON_DISABLE_ENUM_SERIALIZATION 0
 #endif
 
-#ifndef JSON_DELETE_DEPRECATED_FUNCTIONS
-    #define JSON_DELETE_DEPRECATED_FUNCTIONS 0
-#endif
-
 #ifndef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
     #define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 0
 #endif
@@ -4905,21 +4901,6 @@ T conditional_static_cast(U value)
     return value;
 }
 
-// like conditional_static_cast, but converts to bool by comparing with zero,
-// because MSVC 2015 warns about any conversion to bool (C4800), even with an
-// explicit cast; used for enums whose underlying type is bool
-template < typename T, typename U, enable_if_t < !std::is_same<T, bool>::value, int > = 0 >
-T bool_aware_static_cast(U value)
-{
-    return conditional_static_cast<T>(value);
-}
-
-template<typename T, typename U, enable_if_t<std::is_same<T, bool>::value, int> = 0>
-bool bool_aware_static_cast(U value)
-{
-    return value != U();
-}
-
 template<typename... Types>
 using all_integral = conjunction<std::is_integral<Types>...>;
 
@@ -5715,7 +5696,7 @@ inline void from_json(const BasicJsonType& j, EnumType& e)
           typename BasicJsonType::number_unsigned_t, underlying_type>::type;
     value_type val;
     get_arithmetic_value(j, val);
-    e = static_cast<EnumType>(bool_aware_static_cast<underlying_type>(val));
+    e = static_cast<EnumType>(static_cast<underlying_type>(val));
 }
 #endif  // JSON_DISABLE_ENUM_SERIALIZATION
 
@@ -7081,20 +7062,9 @@ struct external_constructor<value_t::object>
 /////////////
 
 #ifdef JSON_HAS_CPP_17
-// whether storing the value of a std::optional<T> cannot throw; MSVC 2017
-// evaluates std::is_nothrow_assignable as true even if T's to_json throws, so
-// the exception would call std::terminate (#5642)
-#if defined(_MSC_VER) && !defined(__clang__) && _MSC_VER < 1920
-    template<typename BasicJsonType, typename T>
-    using is_nothrow_optional_to_json = std::false_type;
-#else
-    template<typename BasicJsonType, typename T>
-    using is_nothrow_optional_to_json = std::is_nothrow_assignable<BasicJsonType&, const T&>;
-#endif
-
 template<typename BasicJsonType, typename T,
          enable_if_t<std::is_constructible<BasicJsonType, T>::value, int> = 0>
-void to_json(BasicJsonType& j, const std::optional<T>& opt) noexcept(is_nothrow_optional_to_json<BasicJsonType, T>::value)
+void to_json(BasicJsonType& j, const std::optional<T>& opt) noexcept(std::is_nothrow_assignable<BasicJsonType&, const T&>::value)
 {
     if (opt.has_value())
     {
@@ -7170,7 +7140,7 @@ inline void to_json(BasicJsonType& j, EnumType e) noexcept
 {
     using underlying_type = typename std::underlying_type<EnumType>::type;
     static constexpr value_t integral_value_t = std::is_unsigned<underlying_type>::value ? value_t::number_unsigned : value_t::number_integer;
-    external_constructor<integral_value_t>::construct(j, bool_aware_static_cast<underlying_type>(e));
+    external_constructor<integral_value_t>::construct(j, static_cast<underlying_type>(e));
 }
 #endif  // JSON_DISABLE_ENUM_SERIALIZATION
 
@@ -14379,11 +14349,10 @@ class binary_reader
         }
 
         // the value is -1 - number, which fits into number_integer_t
-        // whenever number does; the outer cast undoes the integral promotion
+        // whenever number does
-        // for number_integer_t types narrower than int
         if (JSON_HEDLEY_LIKELY(value_in_range_of<number_integer_t>(number)))
         {
-            return sax->number_integer(conditional_static_cast<number_integer_t>(static_cast<number_integer_t>(-1) - static_cast<number_integer_t>(number)));
+            return sax->number_integer(static_cast<number_integer_t>(-1) - static_cast<number_integer_t>(number));
         }
 
         // like the lexer does for JSON text, store a value too small for
@@ -17721,8 +17690,7 @@ class binary_reader
         {
             return sax->number_unsigned(static_cast<number_unsigned_t>(number));
         }
-        // std::isfinite has no integer overloads in MSVC's <cmath>
+        return emit_float(number);
-        return emit_float(static_cast<long double>(number));
     }
 
     /*!
@@ -17745,8 +17713,7 @@ class binary_reader
         {
             return sax->number_unsigned(static_cast<number_unsigned_t>(number));
         }
-        // std::isfinite has no integer overloads in MSVC's <cmath>
+        return emit_float(number);
-        return emit_float(static_cast<long double>(number));
     }
 
     /*!
@@ -17757,8 +17724,7 @@ class binary_reader
     and NaN in the input are passed on unchanged. Integers only overflow if
     number_float_t cannot represent 2^64, e.g., a half-precision type.
 
-    @tparam NumberType a floating-point type (emit_signed and emit_unsigned
+    @tparam NumberType a floating-point or integer type
-                       convert integers to long double first)
     @param[in] number  the number
     @return whether the SAX parser accepted the value
 
@@ -19964,13 +19930,9 @@ class json_pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/operator_string_t/
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, to_string())
     operator string_t() const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return to_string();
     }
-#endif
 
 #ifndef JSON_NO_IO
     /// @brief write string representation of the JSON pointer to stream
@@ -20909,13 +20871,9 @@ class json_pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/operator_eq/
     JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator==(json_pointer))
     bool operator==(const string_t& rhs) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return *this == json_pointer(rhs);
     }
-#endif
 
     /// @brief 3-way compares two JSON pointers
     template<typename RefStringTypeRhs>
@@ -20993,26 +20951,18 @@ template<typename RefStringTypeLhs,
 JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator==(json_pointer, json_pointer))
 inline bool operator==(const json_pointer<RefStringTypeLhs>& lhs,
                        const StringType& rhs)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
 {
     return lhs == json_pointer<RefStringTypeLhs>(rhs);
 }
-#endif
 
 template<typename RefStringTypeRhs,
          typename StringType = typename json_pointer<RefStringTypeRhs>::string_t>
 JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator==(json_pointer, json_pointer))
 inline bool operator==(const StringType& lhs,
                        const json_pointer<RefStringTypeRhs>& rhs)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
 {
     return json_pointer<RefStringTypeRhs>(lhs) == rhs;
 }
-#endif
 
 template<typename RefStringTypeLhs, typename RefStringTypeRhs>
 inline bool operator!=(const json_pointer<RefStringTypeLhs>& lhs,
@@ -21026,26 +20976,18 @@ template<typename RefStringTypeLhs,
 JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator!=(json_pointer, json_pointer))
 inline bool operator!=(const json_pointer<RefStringTypeLhs>& lhs,
                        const StringType& rhs)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
 {
     return !(lhs == rhs);
 }
-#endif
 
 template<typename RefStringTypeRhs,
          typename StringType = typename json_pointer<RefStringTypeRhs>::string_t>
 JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator!=(json_pointer, json_pointer))
 inline bool operator!=(const StringType& lhs,
                        const json_pointer<RefStringTypeRhs>& rhs)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
 {
     return !(lhs == rhs);
 }
-#endif
 
 template<typename RefStringTypeLhs, typename RefStringTypeRhs>
 inline bool operator<(const json_pointer<RefStringTypeLhs>& lhs,
@@ -27792,100 +27734,208 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         /// constructor for rvalue binary arrays (internal type)
         json_value(binary_t&& value) : binary(create<binary_t>(std::move(value))) {}
 
-        void destroy(value_t t)
+        // raw, allocation-free transfer of m_data from src to dst: no
+        // set_parents()/assert_invariant() (the former is O(#children) per
+        // call under JSON_DIAGNOSTICS, which would make the walk below
+        // quadratic); dst takes ownership, src is left as value_t::null.
+        static void take(basic_json& dst, basic_json& src) noexcept
+        {
+            dst.m_data.m_type = src.m_data.m_type;
+            dst.m_data.m_value = src.m_data.m_value;
+            src.m_data.m_type = value_t::null;
+        }
+
+        // true if v is not an array/object, or is an already-empty one
+        static bool has_no_children(const basic_json& v) noexcept
+        {
+            switch (v.m_data.m_type)
+            {
+                case value_t::array:
+                    return v.m_data.m_value.array->empty();
+                case value_t::object:
+                    return v.m_data.m_value.object->empty();
+                default:
+                    return true;
+            }
+        }
+
+        static basic_json& last_child(basic_json& v)
+        {
+            if (v.m_data.m_type == value_t::array)
+            {
+                return v.m_data.m_value.array->back();
+            }
+            JSON_ASSERT(v.m_data.m_type == value_t::object);
+            return v.m_data.m_value.object->rbegin()->second;
+        }
+
+        // removes the last child of a non-empty array/object v; this never
+        // allocates, and since it is only ever called when that child is a
+        // scalar or an already-empty array/object, destroying it never
+        // recurses more than one level deep (see destroy() below)
+        static void pop_last_child(basic_json& v)
+        {
+            if (v.m_data.m_type == value_t::array)
+            {
+                v.m_data.m_value.array->pop_back();
+            }
+            else
+            {
+                JSON_ASSERT(v.m_data.m_type == value_t::object);
+                // erase() needs a forward iterator, so std::prev(end()) is
+                // used here rather than rbegin() (see last_child() above)
+                v.m_data.m_value.object->erase(std::prev(v.m_data.m_value.object->end()));
+            }
+        }
+
+        // deallocates the (already empty) array/object held by v; this is
+        // the same allocator-based free the old recursive implementation
+        // used, just factored out so every level of the walk in destroy()
+        // can share it
+        static void free_container(basic_json& v) noexcept
+        {
+            if (v.m_data.m_type == value_t::array)
+            {
+                JSON_ASSERT(v.m_data.m_value.array->empty());
+                AllocatorType<array_t> alloc;
+                std::allocator_traits<decltype(alloc)>::destroy(alloc, v.m_data.m_value.array);
+                std::allocator_traits<decltype(alloc)>::deallocate(alloc, v.m_data.m_value.array, 1);
+            }
+            else
+            {
+                JSON_ASSERT(v.m_data.m_type == value_t::object);
+                JSON_ASSERT(v.m_data.m_value.object->empty());
+                AllocatorType<object_t> alloc;
+                std::allocator_traits<decltype(alloc)>::destroy(alloc, v.m_data.m_value.object);
+                std::allocator_traits<decltype(alloc)>::deallocate(alloc, v.m_data.m_value.object, 1);
+            }
+            v.m_data.m_type = value_t::null; // avoid a double free if v is later destructed
+        }
+
+        void destroy_string() noexcept
+        {
+            if (string == nullptr)
+            {
+                // not initialized (e.g., due to exception in the ctor)
+                return;
+            }
+            AllocatorType<string_t> alloc;
+            std::allocator_traits<decltype(alloc)>::destroy(alloc, string);
+            std::allocator_traits<decltype(alloc)>::deallocate(alloc, string, 1);
+        }
+
+        void destroy_binary() noexcept
+        {
+            if (binary == nullptr)
+            {
+                // not initialized (e.g., due to exception in the ctor)
+                return;
+            }
+            AllocatorType<binary_t> alloc;
+            std::allocator_traits<decltype(alloc)>::destroy(alloc, binary);
+            std::allocator_traits<decltype(alloc)>::deallocate(alloc, binary, 1);
+        }
+
+        // t must be value_t::array or value_t::object
+        void destroy_container(value_t t) noexcept
         {
             if (
                 (t == value_t::object && object == nullptr) ||
-                (t == value_t::array && array == nullptr) ||
+                (t == value_t::array && array == nullptr)
-                (t == value_t::string && string == nullptr) ||
-                (t == value_t::binary && binary == nullptr)
             )
             {
                 // not initialized (e.g., due to exception in the ctor)
                 return;
             }
-            if (t == value_t::array || t == value_t::object)
+
+            // Destroy the tree without recursing per nesting level and
+            // without any heap allocation: a heap-allocated flattening
+            // stack (the previous implementation) can itself throw
+            // bad_alloc, which would escape this noexcept destructor and
+            // terminate the program (#5135).
+            //
+            // Instead, walk down the "last child" chain, reversing links
+            // as we go: cur is the container currently being emptied,
+            // and prev is its parent (value_t::null when there is none).
+            // Each parent's last child slot doubles as storage for that
+            // parent's own parent link while we are below it, so no
+            // extra memory is needed. We only ever remove a child once
+            // it is a scalar or an empty array/object, which neither
+            // allocates nor recurses more than one level deep.
+            //
+            // This json_value is not itself a basic_json, so the
+            // top-level container is first moved into a local stand-in
+            // ("cur"); a default-constructed basic_json has a null
+            // pointer in its m_value (see data::m_value's initializer),
+            // so swapping it with *this leaves this union's own pointer
+            // null, and it is never looked at or freed a second time.
+            basic_json cur;
+            cur.m_data.m_type = t;
+            using std::swap;
+            swap(cur.m_data.m_value, *this);
+
+            basic_json prev; // value_t::null: no parent
+
+            while (true)
             {
-                // flatten the current json_value to a heap-allocated stack
+                if (has_no_children(cur))
-                std::vector<basic_json> stack;
-
-                // move the top-level items to stack
-                if (t == value_t::array)
                 {
-                    stack.reserve(array->size());
+                    if (prev.m_data.m_type == value_t::null)
-                    std::move(array->begin(), array->end(), std::back_inserter(stack));
-                }
-                else
-                {
-                    stack.reserve(object->size());
-                    for (auto&& it : *object)
                     {
-                        stack.push_back(std::move(it.second));
+                        free_container(cur);
-                    }
+                        return; // back at the top with nothing left to do
-                }
-
-                while (!stack.empty())
-                {
-                    // move the last item to a local variable to be processed
-                    basic_json current_item(std::move(stack.back()));
-                    stack.pop_back();
-
-                    // if current_item is array/object, move
-                    // its children to the stack to be processed later
-                    if (current_item.is_array())
-                    {
-                        std::move(current_item.m_data.m_value.array->begin(), current_item.m_data.m_value.array->end(), std::back_inserter(stack));
-
-                        current_item.m_data.m_value.array->clear();
-                    }
-                    else if (current_item.is_object())
-                    {
-                        for (auto&& it : *current_item.m_data.m_value.object)
-                        {
-                            stack.push_back(std::move(it.second));
-                        }
-
-                        current_item.m_data.m_value.object->clear();
                     }
 
-                    // it's now safe that current_item gets destructed
+                    // ascend: detach the grandparent link from prev's
-                    // since it doesn't have any children
+                    // last slot, drop that (now null) slot, free cur
+                    // (it is empty), then move up one level
+                    basic_json gp;
+                    take(gp, last_child(prev));
+                    pop_last_child(prev);
+
+                    free_container(cur);
+
+                    take(cur, prev);
+                    take(prev, gp);
+                    continue;
                 }
+
+                basic_json& cur_last_ref = last_child(cur);
+
+                if (has_no_children(cur_last_ref))
+                {
+                    // scalar, or already-empty array/object
+                    pop_last_child(cur);
+                    continue;
+                }
+
+                // descend into the non-empty last child, reversing the
+                // link: its slot takes over prev, and the child becomes
+                // the new cur
+                basic_json tmp;
+                take(tmp, cur_last_ref);
+                take(cur_last_ref, prev);
+                take(prev, cur);
+                take(cur, tmp);
             }
+        }
 
+        void destroy(value_t t)
+        {
             switch (t)
             {
-                case value_t::object:
-                {
-                    AllocatorType<object_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, object);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, object, 1);
-                    break;
-                }
-
-                case value_t::array:
-                {
-                    AllocatorType<array_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, array);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, array, 1);
-                    break;
-                }
-
                 case value_t::string:
-                {
+                    destroy_string();
-                    AllocatorType<string_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, string);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, string, 1);
                     break;
-                }
 
                 case value_t::binary:
-                {
+                    destroy_binary();
-                    AllocatorType<binary_t> alloc;
+                    break;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, binary);
+
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, binary, 1);
+                case value_t::object:
+                case value_t::array:
+                    destroy_container(t);
                     break;
-                }
 
                 case value_t::null:
                 case value_t::boolean:
@@ -27894,9 +27944,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                 case value_t::number_float:
                 case value_t::discarded:
                 default:
-                {
                     break;
-                }
             }
         }
     };
@@ -30672,13 +30720,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                    && !std::is_same<value_t, detail::uncvref_t<ValueType>>::value, int > = 0 >
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     ValueType value(const ::nlohmann::json_pointer<BasicJsonType>& ptr, const ValueType& default_value) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return value(ptr.convert(), default_value);
     }
-#endif
 
     template < class ValueType, class BasicJsonType, class ReturnType = typename value_return_type<ValueType>::type,
                detail::enable_if_t <
@@ -30687,13 +30731,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                    && !std::is_same<value_t, detail::uncvref_t<ValueType>>::value, int > = 0 >
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     ReturnType value(const ::nlohmann::json_pointer<BasicJsonType>& ptr, ValueType && default_value) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return value(ptr.convert(), std::forward<ValueType>(default_value));
     }
-#endif
 
     /// @brief access the first element
     /// @sa https://json.nlohmann.me/api/basic_json/front/
@@ -31051,13 +31091,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     bool contains(const typename ::nlohmann::json_pointer<BasicJsonType>& ptr) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.contains(this);
     }
-#endif
 
     /// @}
 
@@ -31168,13 +31204,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     ///             that is, replace `json::iterator_wrapper(j)` with `j.items()`.
     JSON_HEDLEY_DEPRECATED_FOR(3.1.0, items())
     static iteration_proxy<iterator> iterator_wrapper(reference ref) noexcept
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return ref.items();
     }
-#endif
 
     /// @brief wrapper to access iterator member functions in range-based for
     /// @sa https://json.nlohmann.me/api/basic_json/items/
@@ -31183,13 +31215,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     ///         that is, replace `json::iterator_wrapper(j)` with `j.items()`.
     JSON_HEDLEY_DEPRECATED_FOR(3.1.0, items())
     static iteration_proxy<const_iterator> iterator_wrapper(const_reference ref) noexcept
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return ref.items();
     }
-#endif
 
     /// @brief helper to access iterator member functions in range-based for
     /// @sa https://json.nlohmann.me/api/basic_json/items/
@@ -32278,7 +32306,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_le/
     template<typename ScalarType>
     requires std::is_scalar_v<ScalarType>
-    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) <= rhs;
     }
@@ -32287,7 +32315,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ge/
     template<typename ScalarType>
     requires std::is_scalar_v<ScalarType>
-    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) >= rhs;
     }
@@ -32308,16 +32336,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 #endif
     }
 
-    // The friend comparisons with a scalar name the JSON type via decltype of
-    // their parameter in noexcept, because older MSVC versions do not see the
-    // class scope there: MSVC 2015 and 2017 take basic_json as the template,
-    // and MSVC 2019 16.0 rejects member types and template parameters.
-
     /// @brief comparison: equal
     /// @sa https://json.nlohmann.me/api/basic_json/operator_eq/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator==(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator==(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs == basic_json(rhs);
     }
@@ -32326,7 +32349,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_eq/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator==(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator==(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) == rhs;
     }
@@ -32342,7 +32365,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ne/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator!=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator!=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs != basic_json(rhs);
     }
@@ -32351,7 +32374,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ne/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator!=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator!=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) != rhs;
     }
@@ -32371,7 +32394,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_lt/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator<(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs < basic_json(rhs);
     }
@@ -32380,7 +32403,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_lt/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator<(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) < rhs;
     }
@@ -32400,7 +32423,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_le/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator<=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs <= basic_json(rhs);
     }
@@ -32409,7 +32432,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_le/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator<=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) <= rhs;
     }
@@ -32430,7 +32453,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_gt/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator>(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs > basic_json(rhs);
     }
@@ -32439,7 +32462,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_gt/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator>(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) > rhs;
     }
@@ -32459,7 +32482,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ge/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(lhs)>, ScalarType>::value)
+    friend bool operator>=(const_reference lhs, ScalarType rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return lhs >= basic_json(rhs);
     }
@@ -32468,7 +32491,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_ge/
     template<typename ScalarType, typename std::enable_if<
                  std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<detail::uncvref_t<decltype(rhs)>, ScalarType>::value)
+    friend bool operator>=(ScalarType lhs, const_reference rhs) noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value)
     {
         return basic_json(lhs) >= rhs;
     }
@@ -32504,9 +32527,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return o;
     }
 
-#if !JSON_DELETE_DEPRECATED_FUNCTIONS
-    // the deleted version is a function template after the class, because
-    // GCC < 5 and Clang < 10 reject deleted friend functions in class templates
     /// @brief serialize to stream
     /// @sa https://json.nlohmann.me/api/operator_ltlt/
     /// @deprecated This function is deprecated since 3.0.0 and will be removed in
@@ -32518,7 +32538,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     {
         return o << j;
     }
-#endif
 #endif  // JSON_NO_IO
     /// @}
 
@@ -32570,16 +32589,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                             const bool allow_exceptions = true,
                             const bool ignore_comments = false,
                             const bool ignore_trailing_commas = false)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         basic_json result;
         auto p = parser(i.get(), std::move(cb), allow_exceptions, ignore_comments, ignore_trailing_commas);
         p.parse(true, result);
         return result;
     }
-#endif
 
     /// @brief check if the input is valid JSON
     /// @sa https://json.nlohmann.me/api/basic_json/accept/
@@ -32609,13 +32624,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static bool accept(detail::span_input_adapter&& i,
                        const bool ignore_comments = false,
                        const bool ignore_trailing_commas = false)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return parser(i.get(), nullptr, false, ignore_comments, ignore_trailing_commas, true).accept(true);
     }
-#endif
 
     /// @brief generate SAX events
     /// @sa https://json.nlohmann.me/api/basic_json/sax_parse/
@@ -32676,9 +32687,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                           const bool strict = true,
                           const bool ignore_comments = false,
                           const bool ignore_trailing_commas = false)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         auto ia = i.get();
         return format == input_format_t::json
@@ -32687,14 +32695,10 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
                : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict);
     }
-#endif
 #if defined(__clang__)
 #pragma clang diagnostic pop
 #endif
 #ifndef JSON_NO_IO
-#if !JSON_DELETE_DEPRECATED_FUNCTIONS
-    // the deleted version is a function template after the class, because
-    // GCC < 5 and Clang < 10 reject deleted friend functions in class templates
     /// @brief deserialize from stream
     /// @sa https://json.nlohmann.me/api/operator_gtgt/
     /// @deprecated This stream operator is deprecated since 3.0.0 and will be removed in
@@ -32706,7 +32710,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     {
         return operator>>(i, j);
     }
-#endif
 
     /// @brief deserialize from stream
     /// @sa https://json.nlohmann.me/api/operator_gtgt/
@@ -33054,13 +33057,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                                 const bool strict = true,
                                 const bool allow_exceptions = true,
                                 const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return from_cbor(ptr, ptr + len, strict, allow_exceptions, tag_handler);
     }
-#endif
 
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
@@ -33068,13 +33067,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                                 const bool strict = true,
                                 const bool allow_exceptions = true,
                                 const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return from_binary_impl(i.get(), input_format_t::cbor, strict, allow_exceptions, error_handler_t::keep, tag_handler);
     }
-#endif
 
     /// @brief create a JSON value from an input in MessagePack format
     /// @sa https://json.nlohmann.me/api/basic_json/from_msgpack/
@@ -33107,26 +33102,18 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static basic_json from_msgpack(const T* ptr, std::size_t len,
                                    const bool strict = true,
                                    const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return from_msgpack(ptr, ptr + len, strict, allow_exceptions);
     }
-#endif
 
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
     static basic_json from_msgpack(detail::span_input_adapter&& i,
                                    const bool strict = true,
                                    const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return from_binary_impl(i.get(), input_format_t::msgpack, strict, allow_exceptions);
     }
-#endif
 
     /// @brief create a JSON value from an input in UBJSON format
     /// @sa https://json.nlohmann.me/api/basic_json/from_ubjson/
@@ -33159,26 +33146,18 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static basic_json from_ubjson(const T* ptr, std::size_t len,
                                   const bool strict = true,
                                   const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return from_ubjson(ptr, ptr + len, strict, allow_exceptions);
     }
-#endif
 
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
     static basic_json from_ubjson(detail::span_input_adapter&& i,
                                   const bool strict = true,
                                   const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return from_binary_impl(i.get(), input_format_t::ubjson, strict, allow_exceptions);
     }
-#endif
 
     /// @brief create a JSON value from an input in BJData format
     /// @sa https://json.nlohmann.me/api/basic_json/from_bjdata/
@@ -33205,20 +33184,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return from_binary_impl(detail::input_adapter(std::move(first), std::move(last)), input_format_t::bjdata, strict, allow_exceptions, error_handler);
     }
 
-    template<typename T>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.13.0, from_bjdata(ptr, ptr + len))
-    static basic_json from_bjdata(const T* ptr, std::size_t len,
-                                  const bool strict = true,
-                                  const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
-    {
-        return from_bjdata(ptr, ptr + len, strict, allow_exceptions);
-    }
-#endif
-
     /// @brief create a JSON value from an input in BON8 format
     /// @sa https://json.nlohmann.me/api/basic_json/from_bon8/
     template<typename InputType>
@@ -33242,20 +33207,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return from_binary_impl(detail::input_adapter(std::move(first), std::move(last)), input_format_t::bon8, strict, allow_exceptions);
     }
 
-    template<typename T>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.13.0, from_bon8(ptr, ptr + len))
-    static basic_json from_bon8(const T* ptr, std::size_t len,
-                                const bool strict = true,
-                                const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
-    {
-        return from_bon8(ptr, ptr + len, strict, allow_exceptions);
-    }
-#endif
-
     /// @brief create a JSON value from an input in BSON format
     /// @sa https://json.nlohmann.me/api/basic_json/from_bson/
     template<typename InputType>
@@ -33287,26 +33238,18 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     static basic_json from_bson(const T* ptr, std::size_t len,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return from_bson(ptr, ptr + len, strict, allow_exceptions);
     }
-#endif
 
     JSON_HEDLEY_WARN_UNUSED_RESULT
     JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
     static basic_json from_bson(detail::span_input_adapter&& i,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-        = delete;
-#else
     {
         return from_binary_impl(i.get(), input_format_t::bson, strict, allow_exceptions);
     }
-#endif
     /// @}
 
     //////////////////////////
@@ -33326,13 +33269,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.get_unchecked(this);
     }
-#endif
 
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
@@ -33344,13 +33283,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     const_reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.get_unchecked(this);
     }
-#endif
 
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/at/
@@ -33362,13 +33297,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr)
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.get_checked(this);
     }
-#endif
 
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/at/
@@ -33380,13 +33311,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
     JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
     const_reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
-#if JSON_DELETE_DEPRECATED_FUNCTIONS
-    = delete;
-#else
     {
         return ptr.get_checked(this);
     }
-#endif
 
     /// @brief return flattened JSON value
     /// @sa https://json.nlohmann.me/api/basic_json/flatten/
@@ -34363,18 +34290,6 @@ std::string format_as(const NLOHMANN_BASIC_JSON_TPL& j)
     return j.dump();
 }
 
-#if JSON_DELETE_DEPRECATED_FUNCTIONS && !defined(JSON_NO_IO)
-    /// @brief serialize to stream (deleted; use operator<<(std::ostream&, const basic_json&))
-    /// @sa https://json.nlohmann.me/api/operator_ltlt/
-    NLOHMANN_BASIC_JSON_TPL_DECLARATION
-    std::ostream& operator>>(const NLOHMANN_BASIC_JSON_TPL& j, std::ostream& o) = delete;
-
-    /// @brief deserialize from stream (deleted; use operator>>(std::istream&, basic_json&))
-    /// @sa https://json.nlohmann.me/api/operator_gtgt/
-    NLOHMANN_BASIC_JSON_TPL_DECLARATION
-    std::istream& operator<<(NLOHMANN_BASIC_JSON_TPL& j, std::istream& i) = delete;
-#endif
-
 NLOHMANN_JSON_NAMESPACE_END
 
 ///////////////////////
@@ -34558,7 +34473,6 @@ struct formatter<nlohmann::NLOHMANN_BASIC_JSON_TPL, char> // NOLINT(cert-dcl58-c
     #undef JSON_PRECISE_STREAM_POSITION
     #undef JSON_STRICT_NUL_HANDLING
     #undef JSON_STRICT_BINARY_UTF8
-    #undef JSON_DELETE_DEPRECATED_FUNCTIONS
     #undef JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS
 #endif
 

tests/CMakeLists.txt

@@ -8,7 +8,6 @@ set(JSON_SIMDUTF_VERSION 9.1.0 CACHE STRING "The simdutf version used by JSON_Te
 
 set(JSON_32bitTest     AUTO CACHE STRING "Enable the 32bit unit test (ON/OFF/AUTO/ONLY).")
 set(JSON_TestStandards "" CACHE STRING "The list of standards to test explicitly.")
-set(JSON_TestShard     "" CACHE STRING "Build only a part of the unit tests, given as <index>/<count> (e.g. 0/2), to split them across CI jobs with a time limit.")
 
 # using an env var, since this will also affect targets executing cmake (such as "ci_test_compiler_default")
 if (NOT "" STREQUAL "$ENV{JSON_FORCED_GLOBAL_COMPILE_OPTIONS}")
@@ -289,33 +288,6 @@ elseif(NOT json_32bit_test)
     list(FILTER files EXCLUDE REGEX src/unit-32bit.cpp)
 endif()
 
-# with JSON_TestShard=<index>/<count>, keep every <count>-th unit test file,
-# starting at <index> (the glob is sorted, so the split is stable)
-set(test_shard_index 0)
-if(NOT "${JSON_TestShard}" STREQUAL "")
-    if(NOT JSON_TestShard MATCHES "^([0-9]+)/([1-9][0-9]*)$")
-        message(FATAL_ERROR "JSON_TestShard must be <index>/<count>, e.g. 0/2, not '${JSON_TestShard}'.")
-    endif()
-    set(test_shard_index ${CMAKE_MATCH_1})
-    set(test_shard_count ${CMAKE_MATCH_2})
-    if(NOT test_shard_index LESS test_shard_count)
-        message(FATAL_ERROR "JSON_TestShard: the index must be less than the count, not '${JSON_TestShard}'.")
-    endif()
-    list(LENGTH files test_file_count)
-    set(shard_files "")
-    set(file_position 0)
-    foreach(file ${files})
-        math(EXPR file_shard "${file_position} % ${test_shard_count}")
-        if(file_shard EQUAL test_shard_index)
-            list(APPEND shard_files ${file})
-        endif()
-        math(EXPR file_position "${file_position} + 1")
-    endforeach()
-    set(files ${shard_files})
-    list(LENGTH files shard_file_count)
-    message(STATUS "Test shard ${JSON_TestShard}: ${shard_file_count} of ${test_file_count} unit test files")
-endif()
-
 foreach(file ${files})
     json_test_add_test_for(${file} MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force})
 endforeach()
@@ -333,9 +305,6 @@ if(json_32bit_test_only)
     return()
 endif()
 
-# the following variants of single test files are only built in the first shard
-if(test_shard_index EQUAL 0)
-
 # test legacy comparison of discarded values
 json_test_set_test_options(test-comparison_legacy
     COMPILE_DEFINITIONS JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1
@@ -363,8 +332,6 @@ json_test_add_test_for(src/unit-diagnostic-positions.cpp
     MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
 )
 
-endif()
-
 # *DO NOT* use json_test_set_test_options() below this line
 
 #############################################################################

tests/src/unit-allocator.cpp

@@ -521,10 +521,6 @@ struct countdown_allocator : std::allocator<T>
 
 TEST_CASE("converting a deeply nested value from another specialization fails cleanly (#5650)")
 {
-    // MSVC 2015's debug STL constructs the containers' debug proxies through
-    // the allocator in noexcept constructors, so a failing construction crashes
-    // the program there instead of throwing std::bad_alloc. Nothing to check.
-#if !(defined(_MSC_VER) && _MSC_VER < 1910 && defined(_ITERATOR_DEBUG_LEVEL) && _ITERATOR_DEBUG_LEVEL > 0)
     using countdown_json = nlohmann::basic_json<std::map,
           std::vector,
           std::string,
@@ -562,7 +558,6 @@ TEST_CASE("converting a deeply nested value from another specialization fails cl
         }
     }
     CHECK(failures > 0);
-#endif
 }
 
 namespace
@@ -607,3 +602,88 @@ TEST_CASE("bad my_allocator::construct")
         j["test"].push_back("should not leak");
     }
 }
+
+namespace
+{
+std::size_t counting_allocator_allocations = 0;
+std::size_t counting_allocator_deallocations = 0;
+
+template<class T>
+struct counting_allocator : std::allocator<T>
+{
+    using std::allocator<T>::allocator;
+
+    T* allocate(std::size_t n)
+    {
+        ++counting_allocator_allocations;
+        return std::allocator<T>::allocate(n);
+    }
+
+    void deallocate(T* p, std::size_t n)
+    {
+        ++counting_allocator_deallocations;
+        std::allocator<T>::deallocate(p, n);
+    }
+
+    template <class U>
+    struct rebind
+    {
+        using other = counting_allocator<U>;
+    };
+};
+} // namespace
+
+TEST_CASE("destructor performs no allocation, only deallocation")
+{
+    // see https://github.com/nlohmann/json/issues/4842 and
+    // https://github.com/nlohmann/json/issues/5135: destroying nested
+    // arrays/objects used to allocate a temporary stack (first with
+    // std::allocator, later - after #4842 - with the provided allocator).
+    // Since that stack could itself throw bad_alloc from inside the
+    // noexcept destructor (#5135), destroy() no longer allocates anything:
+    // it only ever frees what is already there.
+    using counting_json = nlohmann::basic_json<std::map,
+          std::vector,
+          std::string,
+          bool,
+          std::int64_t,
+          std::uint64_t,
+          double,
+          counting_allocator>;
+
+    SECTION("array")
+    {
+        auto* j = new counting_json({1, {2, {3, 4}}, 5}); // NOLINT(cppcoreguidelines-owning-memory)
+        const auto allocations_before = counting_allocator_allocations;
+        const auto deallocations_before = counting_allocator_deallocations;
+        delete j; // NOLINT(cppcoreguidelines-owning-memory)
+        CHECK(counting_allocator_allocations == allocations_before);
+        CHECK(counting_allocator_deallocations > deallocations_before);
+    }
+
+    SECTION("object")
+    {
+        auto* j = new counting_json({{"a", {{"b", {1, 2}}}}, {"c", 3}}); // NOLINT(cppcoreguidelines-owning-memory)
+        const auto allocations_before = counting_allocator_allocations;
+        const auto deallocations_before = counting_allocator_deallocations;
+        delete j; // NOLINT(cppcoreguidelines-owning-memory)
+        CHECK(counting_allocator_allocations == allocations_before);
+        CHECK(counting_allocator_deallocations > deallocations_before);
+    }
+
+    SECTION("mixed tree of empty/non-empty arrays and objects")
+    {
+        auto* j = new counting_json( // NOLINT(cppcoreguidelines-owning-memory)
+        {
+            {"empty_obj", counting_json::object()},
+            {"empty_arr", counting_json::array()},
+            {"nested", {{"a", counting_json::array({1, 2, counting_json::object()})}, {"b", 3}}},
+            {"tail", counting_json::array({counting_json::array({1}), 2, counting_json::array({3})})}
+        });
+        const auto allocations_before = counting_allocator_allocations;
+        const auto deallocations_before = counting_allocator_deallocations;
+        delete j; // NOLINT(cppcoreguidelines-owning-memory)
+        CHECK(counting_allocator_allocations == allocations_before);
+        CHECK(counting_allocator_deallocations > deallocations_before);
+    }
+}

tests/src/unit-bjdata.cpp

@@ -9,14 +9,6 @@
 #include "doctest_compatibility.h"
 
 #define JSON_TESTS_PRIVATE
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -4498,33 +4490,3 @@ TEST_CASE("BJData roundtrips" * doctest::skip())
         }
     }
 }
-
-TEST_CASE("issue #5648 - from_bjdata(ptr, len) must read len bytes, not treat ptr as a C string")
-{
-    // to_bjdata() encodes the integer 0 as the two bytes 'i' 0x00 (a BJData
-    // type marker followed by the value byte 0x00), so the packed data
-    // below contains a 0x00 byte before its end.
-    const json j = {{"a", 0}};
-    const std::vector<std::uint8_t> packed = json::to_bjdata(j);
-    bool contains_nul = false;
-    for (const auto byte : packed)
-    {
-        contains_nul |= (byte == 0x00);
-    }
-    REQUIRE(contains_nul);
-
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-    // before the fix, from_bjdata had no (ptr, len) overload, so this call
-    // bound to from_bjdata(InputType&&, bool strict) instead: ptr was read
-    // as a NUL-terminated C string (stopping at the embedded 0x00 byte), and
-    // len was silently converted to the strict flag. The deprecated
-    // overload added for this issue forwards to from_bjdata(ptr, ptr + len,
-    // ...) instead, like from_ubjson's deprecated (ptr, len) overload does.
-    json result;
-    CHECK_NOTHROW(result = json::from_bjdata(packed.data(), packed.size()));
-    CHECK(result == j);
-
-    // len must not collapse into the strict flag either
-    CHECK(json::from_bjdata(packed.data(), packed.size(), false) == j);
-#endif
-}

tests/src/unit-bon8.cpp

@@ -8,14 +8,6 @@
 
 #include "doctest_compatibility.h"
 
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 #ifdef JSON_TEST_NO_GLOBAL_UDLS
@@ -1022,36 +1014,6 @@ TEST_CASE("BON8 roundtrips" * doctest::skip())
     }
 }
 
-TEST_CASE("issue #5648 - from_bon8(ptr, len) must read len bytes, not treat ptr as a C string")
-{
-    // to_bon8() encodes the integer 40 as the two bytes 0xC2 0x00 (a BON8
-    // lead byte followed by a continuation byte of 0x00), so the packed data
-    // below contains a 0x00 byte before its end.
-    const json j = {{"a", 40}, {"b", "x"}};
-    const std::vector<std::uint8_t> packed = json::to_bon8(j);
-    bool contains_nul = false;
-    for (const auto byte : packed)
-    {
-        contains_nul |= (byte == 0x00);
-    }
-    REQUIRE(contains_nul);
-
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-    // before the fix, from_bon8 had no (ptr, len) overload, so this call
-    // bound to from_bon8(InputType&&, bool strict) instead: ptr was read as
-    // a NUL-terminated C string (stopping at the embedded 0x00 byte), and
-    // len was silently converted to the strict flag. The deprecated
-    // overload added for this issue forwards to from_bon8(ptr, ptr + len,
-    // ...) instead, like from_cbor's deprecated (ptr, len) overload does.
-    json result;
-    CHECK_NOTHROW(result = json::from_bon8(packed.data(), packed.size()));
-    CHECK(result == j);
-
-    // len must not collapse into the strict flag either
-    CHECK(json::from_bon8(packed.data(), packed.size(), false) == j);
-#endif
-}
-
 #ifdef JSON_HAS_CPP_17
 TEST_CASE("BON8 with std::byte")
 {

tests/src/unit-bson.cpp

@@ -8,14 +8,6 @@
 
 #include "doctest_compatibility.h"
 
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -1269,10 +1261,8 @@ TEST_CASE("BSON input that cannot be read is discarded by every overload")
     CHECK_THROWS_AS(_ = json::from_bson(input.begin(), input.end()), json::parse_error&);
     CHECK(json::from_bson(input, true, false).is_discarded());
     CHECK(json::from_bson(input.begin(), input.end(), true, false).is_discarded());
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     CHECK(json::from_bson(input.data(), input.size(), true, false).is_discarded());
     CHECK(json::from_bson({input.data(), input.size()}, true, false).is_discarded());
-#endif
 }
 
 TEST_CASE("BSON SAX parsing stops at every event")
@@ -1750,7 +1740,6 @@ TEST_CASE("BSON roundtrips" * doctest::skip())
                 CHECK(j1 == j2);
             }
 
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             {
                 INFO_WITH_TEMP(filename + ": uint8_t* and size");
                 // parse JSON file
@@ -1765,7 +1754,6 @@ TEST_CASE("BSON roundtrips" * doctest::skip())
                 // compare parsed JSON values
                 CHECK(j1 == j2);
             }
-#endif
 
             {
                 INFO_WITH_TEMP(filename + ": output to output adapters");

tests/src/unit-cbor.cpp

@@ -8,14 +8,6 @@
 
 #include "doctest_compatibility.h"
 
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -2223,10 +2215,8 @@ TEST_CASE("CBOR input that cannot be read is discarded by every overload")
     CHECK_THROWS_AS(_ = json::from_cbor(input.begin(), input.end()), json::parse_error&);
     CHECK(json::from_cbor(input, true, false).is_discarded());
     CHECK(json::from_cbor(input.begin(), input.end(), true, false).is_discarded());
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     CHECK(json::from_cbor(input.data(), input.size(), true, false).is_discarded());
     CHECK(json::from_cbor({input.data(), input.size()}, true, false).is_discarded());
-#endif
 
     // a string that ends early, read through iterators that are not
     // contiguous and have to be copied from one element at a time
@@ -2623,14 +2613,12 @@ TEST_CASE("CBOR roundtrips" * doctest::skip())
                 CHECK(j1 == j2);
             }
 
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             {
                 INFO_WITH_TEMP(filename + ": uint8_t* and size");
                 json j2;
                 CHECK_NOTHROW(j2 = json::from_cbor({packed.data(), packed.size()}));
                 CHECK(j1 == j2);
             }
-#endif
 
             {
                 INFO_WITH_TEMP(filename + ": output to output adapters");

tests/src/unit-conversions2.cpp

@@ -191,10 +191,8 @@ TEST_CASE("value conversion")
     {
         enum class bool_enum : bool { off, on };
 
-        // the extra parentheses keep doctest from printing the enum via its
+        CHECK(json(bool_enum::off).get<bool_enum>() == bool_enum::off);
-        // underlying type, which MSVC 2015 reports as C4800
+        CHECK(json(bool_enum::on).get<bool_enum>() == bool_enum::on);
-        CHECK((json(bool_enum::off).get<bool_enum>() == bool_enum::off));
-        CHECK((json(bool_enum::on).get<bool_enum>() == bool_enum::on));
     }
 #endif
 
@@ -853,11 +851,8 @@ TEST_CASE("std::optional")
         CHECK_THROWS_WITH_AS(json(opt), "cannot serialize throwing_to_json_type", std::runtime_error&);
 
         // the conversion is noexcept exactly when converting the contained value is
-        // (except with MSVC 2017, where it is never noexcept, see to_json.hpp)
-#if !defined(_MSC_VER) || defined(__clang__) || _MSC_VER >= 1920
         static_assert(!std::is_nothrow_constructible<json, const std::optional<throwing_to_json_type>&>::value);
         static_assert(std::is_nothrow_constructible<json, const std::optional<int>&>::value);
-#endif
     }
 #endif
 }

tests/src/unit-delete_deprecated_functions.cpp

@@ -1,229 +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"
-
-// This file tests the opt-in JSON_DELETE_DEPRECATED_FUNCTIONS, so it defines the
-// macro itself instead of relying on the build configuration.
-#ifdef JSON_DELETE_DEPRECATED_FUNCTIONS
-    #undef JSON_DELETE_DEPRECATED_FUNCTIONS
-#endif
-#define JSON_DELETE_DEPRECATED_FUNCTIONS 1
-
-#include <nlohmann/json.hpp>
-using nlohmann::json;
-
-#include <cstddef>
-#include <cstdint>
-#include <istream>
-#include <ostream>
-#include <sstream>
-#include <string>
-#include <type_traits>
-#include <utility>
-
-namespace
-{
-template<typename...>
-struct make_void
-{
-    using type = void;
-};
-
-template<typename... Ts>
-using void_t = typename make_void<Ts...>::type;
-
-// A deleted function is still found by overload resolution, but naming it in an
-// unevaluated operand is ill-formed, so each of the following traits is false
-// exactly if the expression selects a deleted (or no) function.
-#define JSON_TEST_DETECT(name, expr)                                 \
-    template<typename J, typename = void>                            \
-    struct name : std::false_type {};                                \
-    template<typename J>                                             \
-    struct name<J, void_t<decltype(expr)>> : std::true_type {}
-
-using ptr_t = const std::uint8_t*;
-
-JSON_TEST_DETECT(from_cbor_ptr_len, J::from_cbor(std::declval<ptr_t>(), std::declval<std::size_t>()));
-JSON_TEST_DETECT(from_msgpack_ptr_len, J::from_msgpack(std::declval<ptr_t>(), std::declval<std::size_t>()));
-JSON_TEST_DETECT(from_ubjson_ptr_len, J::from_ubjson(std::declval<ptr_t>(), std::declval<std::size_t>()));
-JSON_TEST_DETECT(from_bjdata_ptr_len, J::from_bjdata(std::declval<ptr_t>(), std::declval<std::size_t>()));
-JSON_TEST_DETECT(from_bon8_ptr_len, J::from_bon8(std::declval<ptr_t>(), std::declval<std::size_t>()));
-JSON_TEST_DETECT(from_bson_ptr_len, J::from_bson(std::declval<ptr_t>(), std::declval<std::size_t>()));
-
-JSON_TEST_DETECT(from_cbor_ptr_ptr, J::from_cbor(std::declval<ptr_t>(), std::declval<ptr_t>()));
-JSON_TEST_DETECT(from_msgpack_ptr_ptr, J::from_msgpack(std::declval<ptr_t>(), std::declval<ptr_t>()));
-JSON_TEST_DETECT(from_ubjson_ptr_ptr, J::from_ubjson(std::declval<ptr_t>(), std::declval<ptr_t>()));
-JSON_TEST_DETECT(from_bjdata_ptr_ptr, J::from_bjdata(std::declval<ptr_t>(), std::declval<ptr_t>()));
-JSON_TEST_DETECT(from_bon8_ptr_ptr, J::from_bon8(std::declval<ptr_t>(), std::declval<ptr_t>()));
-JSON_TEST_DETECT(from_bson_ptr_ptr, J::from_bson(std::declval<ptr_t>(), std::declval<ptr_t>()));
-
-JSON_TEST_DETECT(from_cbor_init_list, J::from_cbor({std::declval<ptr_t>(), std::declval<std::size_t>()}));
-JSON_TEST_DETECT(from_msgpack_init_list, J::from_msgpack({std::declval<ptr_t>(), std::declval<std::size_t>()}));
-JSON_TEST_DETECT(from_ubjson_init_list, J::from_ubjson({std::declval<ptr_t>(), std::declval<std::size_t>()}));
-JSON_TEST_DETECT(from_bson_init_list, J::from_bson({std::declval<ptr_t>(), std::declval<std::size_t>()}));
-
-JSON_TEST_DETECT(parse_init_list, J::parse({std::declval<ptr_t>(), std::declval<std::size_t>()}));
-JSON_TEST_DETECT(accept_init_list, J::accept({std::declval<ptr_t>(), std::declval<std::size_t>()}));
-JSON_TEST_DETECT(sax_parse_init_list, J::sax_parse({std::declval<ptr_t>(), std::declval<std::size_t>()}, std::declval<nlohmann::json_sax<J>*>()));
-JSON_TEST_DETECT(parse_ptr_ptr, J::parse(std::declval<ptr_t>(), std::declval<ptr_t>()));
-
-JSON_TEST_DETECT(iterator_wrapper, J::iterator_wrapper(std::declval<J&>()));
-JSON_TEST_DETECT(iterator_wrapper_const, J::iterator_wrapper(std::declval<const J&>()));
-JSON_TEST_DETECT(items, std::declval<J&>().items());
-
-JSON_TEST_DETECT(json_ltlt_istream, std::declval<J&>() << std::declval<std::istream&>());
-JSON_TEST_DETECT(istream_gtgt_json, std::declval<std::istream&>() >> std::declval<J&>());
-JSON_TEST_DETECT(json_gtgt_ostream, std::declval<const J&>() >> std::declval<std::ostream&>());
-JSON_TEST_DETECT(ostream_ltlt_json, std::declval<std::ostream&>() << std::declval<const J&>());
-
-JSON_TEST_DETECT(ptr_eq_ptr, std::declval<const typename J::json_pointer&>() == std::declval<const typename J::json_pointer&>());
-JSON_TEST_DETECT(ptr_ne_ptr, std::declval<const typename J::json_pointer&>() != std::declval<const typename J::json_pointer&>());
-JSON_TEST_DETECT(ptr_eq_string, std::declval<const typename J::json_pointer&>() == std::declval<const std::string&>());
-JSON_TEST_DETECT(string_eq_ptr, std::declval<const std::string&>() == std::declval<const typename J::json_pointer&>());
-JSON_TEST_DETECT(ptr_eq_c_string, std::declval<const typename J::json_pointer&>() == std::declval<const char*>());
-JSON_TEST_DETECT(c_string_eq_ptr, std::declval<const char*>() == std::declval<const typename J::json_pointer&>());
-JSON_TEST_DETECT(ptr_ne_string, std::declval<const typename J::json_pointer&>() != std::declval<const std::string&>());
-JSON_TEST_DETECT(string_ne_ptr, std::declval<const std::string&>() != std::declval<const typename J::json_pointer&>());
-JSON_TEST_DETECT(ptr_to_string, std::declval<const typename J::json_pointer&>().to_string());
-
-// json_pointer with a basic_json type as template argument
-template<typename J>
-using legacy_ptr_t = const nlohmann::json_pointer<J>& ;
-JSON_TEST_DETECT(legacy_ptr_value, std::declval<const J&>().value(std::declval<legacy_ptr_t<J>>(), 0));
-JSON_TEST_DETECT(legacy_ptr_value_rvalue, std::declval<const J&>().value(std::declval<legacy_ptr_t<J>>(), std::string()));
-JSON_TEST_DETECT(legacy_ptr_contains, std::declval<const J&>().contains(std::declval<legacy_ptr_t<J>>()));
-JSON_TEST_DETECT(legacy_ptr_subscript, std::declval<J&>()[std::declval<legacy_ptr_t<J>>()]);
-JSON_TEST_DETECT(legacy_ptr_subscript_const, std::declval<const J&>()[std::declval<legacy_ptr_t<J>>()]);
-JSON_TEST_DETECT(legacy_ptr_at, std::declval<J&>().at(std::declval<legacy_ptr_t<J>>()));
-JSON_TEST_DETECT(legacy_ptr_at_const, std::declval<const J&>().at(std::declval<legacy_ptr_t<J>>()));
-JSON_TEST_DETECT(ptr_value, std::declval<const J&>().value(std::declval<const typename J::json_pointer&>(), 0));
-JSON_TEST_DETECT(ptr_at, std::declval<J&>().at(std::declval<const typename J::json_pointer&>()));
-
-#undef JSON_TEST_DETECT
-} // namespace
-
-TEST_CASE("JSON_DELETE_DEPRECATED_FUNCTIONS")
-{
-    // MSVC 2015 does not treat selecting a deleted function in decltype as a
-    // substitution failure, so the traits cannot tell deleted functions apart
-    // there; calling them still fails to compile
-#if !(defined(_MSC_VER) && _MSC_VER < 1910)
-    SECTION("from_* with a pointer and a length")
-    {
-        // the overloads are deleted rather than removed, so the length cannot
-        // silently bind to the strict parameter of from_*(InputType&&, bool)
-        CHECK_FALSE(from_cbor_ptr_len<json>::value);
-        CHECK_FALSE(from_msgpack_ptr_len<json>::value);
-        CHECK_FALSE(from_ubjson_ptr_len<json>::value);
-        CHECK_FALSE(from_bjdata_ptr_len<json>::value);
-        CHECK_FALSE(from_bon8_ptr_len<json>::value);
-        CHECK_FALSE(from_bson_ptr_len<json>::value);
-
-        // the replacement
-        CHECK(from_cbor_ptr_ptr<json>::value);
-        CHECK(from_msgpack_ptr_ptr<json>::value);
-        CHECK(from_ubjson_ptr_ptr<json>::value);
-        CHECK(from_bjdata_ptr_ptr<json>::value);
-        CHECK(from_bon8_ptr_ptr<json>::value);
-        CHECK(from_bson_ptr_ptr<json>::value);
-    }
-
-    SECTION("initializer lists of a pointer and a length")
-    {
-        CHECK_FALSE(from_cbor_init_list<json>::value);
-        CHECK_FALSE(from_msgpack_init_list<json>::value);
-        CHECK_FALSE(from_ubjson_init_list<json>::value);
-        CHECK_FALSE(from_bson_init_list<json>::value);
-        CHECK_FALSE(parse_init_list<json>::value);
-        CHECK_FALSE(accept_init_list<json>::value);
-        CHECK_FALSE(sax_parse_init_list<json>::value);
-
-        // the replacement
-        CHECK(parse_ptr_ptr<json>::value);
-    }
-
-    SECTION("iterator_wrapper")
-    {
-        CHECK_FALSE(iterator_wrapper<json>::value);
-        CHECK_FALSE(iterator_wrapper_const<json>::value);
-
-        // the replacement
-        CHECK(items<json>::value);
-    }
-
-    SECTION("stream operators with reversed operands")
-    {
-        CHECK_FALSE(json_ltlt_istream<json>::value);
-        CHECK_FALSE(json_gtgt_ostream<json>::value);
-
-        // the replacement
-        CHECK(istream_gtgt_json<json>::value);
-        CHECK(ostream_ltlt_json<json>::value);
-    }
-
-    SECTION("json_pointer")
-    {
-        // conversion to a string
-        CHECK_FALSE(std::is_constructible<std::string, json::json_pointer>::value);
-        CHECK_FALSE(std::is_convertible<json::json_pointer, std::string>::value);
-
-        // comparison with a string
-        CHECK_FALSE(ptr_eq_string<json>::value);
-        CHECK_FALSE(string_eq_ptr<json>::value);
-        CHECK_FALSE(ptr_eq_c_string<json>::value);
-        CHECK_FALSE(c_string_eq_ptr<json>::value);
-        CHECK_FALSE(ptr_ne_string<json>::value);
-        CHECK_FALSE(string_ne_ptr<json>::value);
-
-        // the replacement
-        CHECK(ptr_to_string<json>::value);
-        CHECK(ptr_eq_ptr<json>::value);
-        CHECK(ptr_ne_ptr<json>::value);
-    }
-
-    SECTION("json_pointer with a basic_json type as template argument")
-    {
-        CHECK_FALSE(legacy_ptr_value<json>::value);
-        CHECK_FALSE(legacy_ptr_value_rvalue<json>::value);
-        CHECK_FALSE(legacy_ptr_contains<json>::value);
-        CHECK_FALSE(legacy_ptr_subscript<json>::value);
-        CHECK_FALSE(legacy_ptr_subscript_const<json>::value);
-        CHECK_FALSE(legacy_ptr_at<json>::value);
-        CHECK_FALSE(legacy_ptr_at_const<json>::value);
-
-        // the replacement
-        CHECK(ptr_value<json>::value);
-        CHECK(ptr_at<json>::value);
-    }
-
-#endif
-
-    SECTION("the non-deprecated functions still work")
-    {
-        const json j = {{"a", {1, 2}}};
-        const auto cbor = json::to_cbor(j);
-        CHECK(json::from_cbor(cbor.data(), cbor.data() + cbor.size()) == j);
-
-        const json::json_pointer ptr("/a/1");
-        CHECK(ptr == json::json_pointer("/a/1"));
-        CHECK(ptr.to_string() == "/a/1");
-        CHECK(j[ptr] == 2);
-        CHECK(j.at(ptr) == 2);
-        CHECK(j.value(ptr, 0) == 2);
-        CHECK(j.contains(ptr));
-
-        std::ostringstream os;
-        os << j;
-        CHECK(os.str() == R"({"a":[1,2]})");
-        std::istringstream is(os.str());
-        json parsed;
-        is >> parsed;
-        CHECK(parsed == j);
-    }
-}

tests/src/unit-deserialization.cpp

@@ -16,14 +16,6 @@
     #define JSON_TEST_STRICT_NUL_HANDLING_ENABLED 1
 #endif
 
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 #ifdef JSON_TEST_NO_GLOBAL_UDLS
@@ -299,7 +291,6 @@ TEST_CASE("deserialization")
             }));
         }
 
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
         SECTION("operator<<")
         {
             std::stringstream ss;
@@ -308,7 +299,6 @@ TEST_CASE("deserialization")
             j << ss;
             CHECK(j == json({"foo", 1, 2, 3, false, {{"one", 1}}}));
         }
-#endif
 
         SECTION("operator>>")
         {
@@ -433,7 +423,6 @@ TEST_CASE("deserialization")
             CHECK_THROWS_WITH_AS(_ = json::parse(nullptr), "[json.exception.parse_error.101] parse error: attempting to parse an empty input; check that your input string or stream contains the expected JSON", json::parse_error&);
         }
 
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
         SECTION("operator<<")
         {
             std::stringstream ss;
@@ -441,7 +430,6 @@ TEST_CASE("deserialization")
             json j;
             CHECK_THROWS_WITH_AS(j << ss, "[json.exception.parse_error.101] parse error at line 1, column 29: syntax error while parsing array - unexpected end of input; expected ']'", json::parse_error&);
         }
-#endif
 
         SECTION("operator>>")
         {
@@ -1160,9 +1148,9 @@ TEST_CASE("deserialization")
         {
             std::istringstream s(bom + "123 456");
             json j;
-            s >> j;
+            j << s;
             CHECK(j == 123);
-            s >> j;
+            j << s;
             CHECK(j == 456);
         }
     }

tests/src/unit-element_access2.cpp

@@ -1551,10 +1551,6 @@ TEST_CASE_TEMPLATE("element access 2", Json, nlohmann::json, nlohmann::ordered_j
         // count(0) used to compile and then crash instead of failing to compile
         using nlohmann::detail::is_detected;
 
-        // MSVC 2015 does not treat selecting a deleted function in decltype as
-        // a substitution failure, so it detects the deleted overloads as
-        // callable; calling them still fails to compile
-#if !(defined(_MSC_VER) && _MSC_VER < 1910)
         CHECK_FALSE(is_detected<can_call_find_with_0, Json&>::value);
         CHECK_FALSE(is_detected<can_call_find_with_0, const Json&>::value);
         CHECK_FALSE(is_detected<can_call_count_with_0, Json&>::value);
@@ -1566,7 +1562,6 @@ TEST_CASE_TEMPLATE("element access 2", Json, nlohmann::json, nlohmann::ordered_j
 
         // another integral literal type must be rejected as well, not just int
         CHECK_FALSE(is_detected<can_call_contains_with_0L, Json&>::value);
-#endif
 
         // the valid overloads must remain callable
         CHECK(is_detected<can_call_find, Json&, const char*>::value);

tests/src/unit-items.cpp

@@ -8,14 +8,6 @@
 
 #include "doctest_compatibility.h"
 
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -27,7 +19,6 @@ DOCTEST_GCC_SUPPRESS_WARNING_PUSH
 DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
 DOCTEST_CLANG_SUPPRESS_WARNING("-Wrange-loop-construct")
 
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
 TEST_CASE("iterator_wrapper")
 {
     SECTION("object")
@@ -724,7 +715,6 @@ TEST_CASE("iterator_wrapper")
         }
     }
 }
-#endif
 
 TEST_CASE("items()")
 {

tests/src/unit-json_pointer.cpp

@@ -9,14 +9,6 @@
 #include "doctest_compatibility.h"
 
 #define JSON_TESTS_PRIVATE
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 #ifdef JSON_TEST_NO_GLOBAL_UDLS
@@ -572,9 +564,7 @@ TEST_CASE("JSON pointers")
             std::stringstream ss;
             ss << ptr;
             CHECK(ptr.to_string() == ptr_str);
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             CHECK(std::string(ptr) == ptr_str);
-#endif
             CHECK(ss.str() == ptr_str);
         }
     }
@@ -754,6 +744,8 @@ TEST_CASE("JSON pointers")
 
     SECTION("equality comparison")
     {
+        const char* ptr_cpstring = "/foo/bar";
+        const char ptr_castring[] = "/foo/bar"; // NOLINT(misc-const-correctness,hicpp-avoid-c-arrays,modernize-avoid-c-arrays,cppcoreguidelines-avoid-c-arrays)
         std::string ptr_string{"/foo/bar"};
         auto ptr1 = json::json_pointer(ptr_string);
         auto ptr2 = json::json_pointer(ptr_string);
@@ -763,12 +755,6 @@ TEST_CASE("JSON pointers")
 
         CHECK(ptr1 == ptr2);
 
-        CHECK_FALSE(ptr1 != ptr2);
-
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-        const char* ptr_cpstring = "/foo/bar";
-        const char ptr_castring[] = "/foo/bar"; // NOLINT(misc-const-correctness,hicpp-avoid-c-arrays,modernize-avoid-c-arrays,cppcoreguidelines-avoid-c-arrays)
-
         CHECK(ptr1 == "/foo/bar");
         CHECK(ptr1 == ptr_cpstring);
         CHECK(ptr1 == ptr_castring);
@@ -779,6 +765,8 @@ TEST_CASE("JSON pointers")
         CHECK(ptr_castring == ptr1);
         CHECK(ptr_string == ptr1);
 
+        CHECK_FALSE(ptr1 != ptr2);
+
         CHECK_FALSE(ptr1 != "/foo/bar");
         CHECK_FALSE(ptr1 != ptr_cpstring);
         CHECK_FALSE(ptr1 != ptr_castring);
@@ -800,7 +788,6 @@ TEST_CASE("JSON pointers")
             CHECK_THROWS_WITH_AS("/~~" == ptr1,
                                  "[json.exception.parse_error.108] parse error: escape character '~' must be followed with '0' or '1'", json::parse_error&);
         }
-#endif
     }
 
     SECTION("less-than comparison")
@@ -852,7 +839,6 @@ TEST_CASE("JSON pointers")
         json_ptr_j ptr_j{ptr_string};
         json_ptr_oj ptr_oj{ptr_string};
 
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
         CHECK(j.contains(ptr));
         CHECK(j.contains(ptr_j));
         CHECK(j.contains(ptr_oj));
@@ -865,7 +851,6 @@ TEST_CASE("JSON pointers")
 
         CHECK(j.value(ptr, "x") == j.value(ptr_j, "x"));
         CHECK(j.value(ptr, "x") == j.value(ptr_oj, "x"));
-#endif
 
         CHECK(ptr == ptr_j);
         CHECK(ptr == ptr_oj);

tests/src/unit-msgpack.cpp

@@ -8,14 +8,6 @@
 
 #include "doctest_compatibility.h"
 
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 #ifdef JSON_TEST_NO_GLOBAL_UDLS
@@ -1803,10 +1795,8 @@ TEST_CASE("MessagePack input that cannot be read is discarded by every overload"
     CHECK_THROWS_AS(_ = json::from_msgpack(input.begin(), input.end()), json::parse_error&);
     CHECK(json::from_msgpack(input, true, false).is_discarded());
     CHECK(json::from_msgpack(input.begin(), input.end(), true, false).is_discarded());
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     CHECK(json::from_msgpack(input.data(), input.size(), true, false).is_discarded());
     CHECK(json::from_msgpack({input.data(), input.size()}, true, false).is_discarded());
-#endif
 }
 
 TEST_CASE("MessagePack SAX parsing stops at every event")
@@ -2109,14 +2099,12 @@ TEST_CASE("MessagePack roundtrips" * doctest::skip())
                 CHECK(j1 == j2);
             }
 
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             {
                 INFO_WITH_TEMP(filename + ": uint8_t* and size");
                 json j2;
                 CHECK_NOTHROW(j2 = json::from_msgpack({packed.data(), packed.size()}));
                 CHECK(j1 == j2);
             }
-#endif
 
             {
                 INFO_WITH_TEMP(filename + ": output to output adapters");

tests/src/unit-regression2.cpp

@@ -40,7 +40,9 @@ using ordered_json = nlohmann::ordered_json;
 #endif
 
 #include <cstdio>
+#include <cstdlib>
 #include <list>
+#include <new>
 #include <tuple>
 #include <type_traits>
 #include <utility>
@@ -107,6 +109,84 @@ DOCTEST_CLANG_SUPPRESS_WARNING("-Wexit-time-destructors")
 
 using float_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, float>;
 
+#if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)) && !defined(JSON_NOEXCEPTION)
+namespace
+{
+// An allocator whose allocate() can be told to fail on demand, so tests can
+// check that ~basic_json() tolerates - in fact, after #5135, never even
+// triggers - an allocation failure. This replaces an earlier version of
+// this test that overrode the process-wide ::operator new/::operator
+// delete, which affected every allocation in the whole unit-regression2
+// binary rather than just the values under test.
+std::size_t failing_allocator_allocations = 0;
+std::size_t failing_allocator_deallocations = 0;
+bool fail_next_allocation = false;
+
+template<class T>
+struct failing_allocator : std::allocator<T>
+{
+    using std::allocator<T>::allocator;
+
+    failing_allocator() noexcept = default;
+    template<class U>
+    failing_allocator(const failing_allocator<U>& /*unused*/) noexcept {} // NOLINT(google-explicit-constructor)
+
+    T* allocate(std::size_t n)
+    {
+        if (fail_next_allocation)
+        {
+            fail_next_allocation = false;
+            throw std::bad_alloc();
+        }
+        ++failing_allocator_allocations;
+        return std::allocator<T>::allocate(n);
+    }
+
+    void deallocate(T* p, std::size_t n)
+    {
+        ++failing_allocator_deallocations;
+        std::allocator<T>::deallocate(p, n);
+    }
+
+    template<class U>
+    struct rebind
+    {
+        using other = failing_allocator<U>;
+    };
+};
+
+using failing_json = nlohmann::basic_json<std::map, std::vector, std::string, bool,
+      std::int64_t, std::uint64_t, double, failing_allocator>;
+using failing_ordered_json = nlohmann::basic_json<nlohmann::ordered_map, std::vector, std::string, bool,
+      std::int64_t, std::uint64_t, double, failing_allocator>;
+
+// builds `depth` levels of nesting around a scalar, iteratively (never
+// recursing: each wrap only moves the previous, already-built value, which
+// is O(1)), each level an array or an object depending on `nest_objects`
+template<class BasicJsonType>
+BasicJsonType make_deep_nest(std::size_t depth, bool nest_objects)
+{
+    BasicJsonType v = 0;
+    for (std::size_t i = 0; i < depth; ++i)
+    {
+        if (nest_objects)
+        {
+            BasicJsonType wrapper = BasicJsonType::object();
+            wrapper["x"] = std::move(v);
+            v = std::move(wrapper);
+        }
+        else
+        {
+            BasicJsonType wrapper = BasicJsonType::array();
+            wrapper.push_back(std::move(v));
+            v = std::move(wrapper);
+        }
+    }
+    return v;
+}
+} // namespace
+#endif
+
 /////////////////////////////////////////////////////////////////////
 // for #1647
 /////////////////////////////////////////////////////////////////////
@@ -569,7 +649,7 @@ TEST_CASE("regression tests 2")
     SECTION("issue #2067 - cannot serialize binary data to text JSON")
     {
         const std::array<unsigned char, 23> data = {{0x81, 0xA4, 0x64, 0x61, 0x74, 0x61, 0xC4, 0x0F, 0x33, 0x30, 0x30, 0x32, 0x33, 0x34, 0x30, 0x31, 0x30, 0x37, 0x30, 0x35, 0x30, 0x31, 0x30}};
-        const json j = json::from_msgpack(data.begin(), data.end());
+        const json j = json::from_msgpack(data.data(), data.size());
         // dump() is nodiscard; this only checks that dumping does not throw
         CHECK_NOTHROW(
             utils::ignore_return_value(
@@ -940,4 +1020,211 @@ TEST_CASE("regression test - excessive binary container size honors allow_except
     CHECK(json::from_cbor(std::vector<std::uint8_t> {0x9b, 0, 0, 0, 0, 0, 0, 0, 0x02}, true, false).is_discarded());
 }
 
+#if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)) && !defined(JSON_NOEXCEPTION)
+TEST_CASE("regression test #5135 - destructor never allocates, even under memory pressure")
+{
+    // Before the fix, ~basic_json() flattened a nested array/object into a
+    // heap-allocated std::vector to avoid recursing; that allocation could
+    // itself throw bad_alloc, which escapes a noexcept destructor and
+    // terminates the program. destroy() no longer allocates anything, so
+    // none of the sections below ever observe fail_next_allocation being
+    // consumed: CHECK(fail_next_allocation) confirms it was never touched.
+
+    SECTION("the original report: a small, mixed array/object nest")
+    {
+        failing_allocator_allocations = 0;
+        failing_allocator_deallocations = 0;
+        {
+            failing_json j = failing_json::array(
+            {
+                failing_json::array({1, 2}),
+                failing_json::object({{"key", failing_json::array({3})}})
+            });
+            fail_next_allocation = true;
+        } // j is destroyed here, with every further allocation set to fail
+
+        CHECK(fail_next_allocation);
+        fail_next_allocation = false;
+        CHECK(failing_allocator_deallocations > 0);
+    }
+
+    SECTION("100000-deep nested array")
+    {
+        std::size_t allocations_before = 0;
+        {
+            failing_json j = make_deep_nest<failing_json>(100000, false);
+            allocations_before = failing_allocator_allocations;
+            fail_next_allocation = true;
+        }
+
+        CHECK(fail_next_allocation);
+        fail_next_allocation = false;
+        CHECK(failing_allocator_allocations == allocations_before);
+    }
+
+    SECTION("100000-deep nested object")
+    {
+        std::size_t allocations_before = 0;
+        {
+            failing_json j = make_deep_nest<failing_json>(100000, true);
+            allocations_before = failing_allocator_allocations;
+            fail_next_allocation = true;
+        }
+
+        CHECK(fail_next_allocation);
+        fail_next_allocation = false;
+        CHECK(failing_allocator_allocations == allocations_before);
+    }
+
+    SECTION("100000-deep nested ordered_json")
+    {
+        std::size_t allocations_before = 0;
+        {
+            failing_ordered_json j = make_deep_nest<failing_ordered_json>(100000, true);
+            allocations_before = failing_allocator_allocations;
+            fail_next_allocation = true;
+        }
+
+        CHECK(fail_next_allocation);
+        fail_next_allocation = false;
+        CHECK(failing_allocator_allocations == allocations_before);
+    }
+
+    SECTION("wide and deep: 1000 arrays of 1000 elements, each a small nested object")
+    {
+        std::size_t allocations_before = 0;
+        {
+            failing_json wide = failing_json::array();
+            for (std::size_t i = 0; i < 1000; ++i)
+            {
+                failing_json inner = failing_json::array();
+                for (std::size_t k = 0; k < 1000; ++k)
+                {
+                    inner.push_back(failing_json::object({{"a", 1}, {"b", failing_json::array({1, 2, 3})}}));
+                }
+                wide.push_back(std::move(inner));
+            }
+
+            allocations_before = failing_allocator_allocations;
+            fail_next_allocation = true;
+        }
+
+        CHECK(fail_next_allocation);
+        fail_next_allocation = false;
+        CHECK(failing_allocator_allocations == allocations_before);
+    }
+}
+#endif
+
+namespace
+{
+// a single-element chain of `depth` arrays, built iteratively (never
+// recursing: each wrap only moves the previous, already-built value)
+template<class BasicJsonType>
+BasicJsonType make_single_chain(std::size_t depth)
+{
+    BasicJsonType v = 1;
+    for (std::size_t i = 0; i < depth; ++i)
+    {
+        BasicJsonType wrapper = BasicJsonType::array();
+        wrapper.push_back(std::move(v));
+        v = std::move(wrapper);
+    }
+    return v;
+}
+
+// copies value first, to make sure nothing was corrupted by building it,
+// then lets both the copy and the original destruct via normal scope exit
+template<class BasicJsonType>
+void check_destroy_edge_case(const BasicJsonType& value)
+{
+    const BasicJsonType copy = value;
+    CHECK(copy == value);
+}
+} // namespace
+
+TEST_CASE_TEMPLATE("regression test #5135 - destroy() edge cases", BasicJsonType, json, ordered_json)
+{
+    using binary_t = typename BasicJsonType::binary_t;
+
+    SECTION("mix of empty objects, empty arrays, non-empty containers, and scalars")
+    {
+        BasicJsonType root = BasicJsonType::array();
+        root.push_back(BasicJsonType::object());
+        root.push_back(BasicJsonType::array());
+        root.push_back(BasicJsonType::object({{"k", 1}}));
+        root.push_back(BasicJsonType::array({1, 2, 3}));
+        root.push_back(nullptr);
+        root.push_back(true);
+        root.push_back(42);
+        root.push_back(3.14);
+        root.push_back("a string");
+        root.push_back(BasicJsonType(binary_t({1, 2, 3})));
+        check_destroy_edge_case(root);
+    }
+
+    SECTION("container child in first position only")
+    {
+        BasicJsonType root = BasicJsonType::array({BasicJsonType::array({1, 2}), 3, 4, 5});
+        check_destroy_edge_case(root);
+    }
+
+    SECTION("container child in last position only")
+    {
+        BasicJsonType root = BasicJsonType::array({1, 2, 3, BasicJsonType::array({4, 5})});
+        check_destroy_edge_case(root);
+    }
+
+    SECTION("container children in first and last position")
+    {
+        BasicJsonType root = BasicJsonType::array({BasicJsonType::array({1}), 2, 3, BasicJsonType::array({4})});
+        check_destroy_edge_case(root);
+    }
+
+    SECTION("single-element chain, 1000 levels deep")
+    {
+        BasicJsonType root = make_single_chain<BasicJsonType>(1000);
+        check_destroy_edge_case(root);
+    }
+
+    SECTION("top-level empty array")
+    {
+        BasicJsonType root = BasicJsonType::array();
+        check_destroy_edge_case(root);
+    }
+
+    SECTION("top-level empty object")
+    {
+        BasicJsonType root = BasicJsonType::object();
+        check_destroy_edge_case(root);
+    }
+
+    SECTION("object whose last child is a non-empty array whose last child is an empty object")
+    {
+        BasicJsonType inner_array = BasicJsonType::array({1, 2, BasicJsonType::object()});
+        BasicJsonType root = BasicJsonType::object({{"a", 1}, {"b", inner_array}});
+        check_destroy_edge_case(root);
+    }
+
+    SECTION("destruction via erase() on a deeply nested child")
+    {
+        BasicJsonType root = BasicJsonType::array();
+        root.push_back(make_single_chain<BasicJsonType>(500));
+        root.push_back(BasicJsonType::object({{"k", BasicJsonType::array({1, 2, 3})}}));
+        // erase() must destroy the removed subtree without recursing or
+        // allocating beyond what erase() itself needs
+        root.erase(0);
+        CAPTURE(root.size())
+        CHECK(root.size() == 1);
+    }
+
+    SECTION("destruction via assignment on a deep tree")
+    {
+        BasicJsonType root = make_single_chain<BasicJsonType>(2000);
+        // assigning a new value destroys the old one in place
+        root = nullptr;
+        CHECK(root.is_null());
+    }
+}
+
 DOCTEST_CLANG_SUPPRESS_WARNING_POP

tests/src/unit-serialization.cpp

@@ -8,14 +8,6 @@
 
 #include "doctest_compatibility.h"
 
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -56,7 +48,6 @@ TEST_CASE("serialization")
         }
     }
 
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     SECTION("operator>>")
     {
         SECTION("no given width")
@@ -88,7 +79,6 @@ TEST_CASE("serialization")
                   "[\n\t\"foo\",\n\t1,\n\t2,\n\t3,\n\tfalse,\n\t{\n\t\t\"one\": 1\n\t}\n]");
         }
     }
-#endif
 
     SECTION("dump")
     {

tests/src/unit-ubjson.cpp

@@ -8,14 +8,6 @@
 
 #include "doctest_compatibility.h"
 
-// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
-// line *before* including json.hpp, since the library #undefs it once the header
-// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
-// tests of deprecated functions are skipped if these functions are deleted
-#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
-    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
-#endif
-
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -2220,10 +2212,8 @@ TEST_CASE("UBJSON input that cannot be read is discarded by every overload")
     CHECK_THROWS_AS(_ = json::from_ubjson(input.begin(), input.end()), json::parse_error&);
     CHECK(json::from_ubjson(input, true, false).is_discarded());
     CHECK(json::from_ubjson(input.begin(), input.end(), true, false).is_discarded());
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     CHECK(json::from_ubjson(input.data(), input.size(), true, false).is_discarded());
     CHECK(json::from_ubjson({input.data(), input.size()}, true, false).is_discarded());
-#endif
 }
 
 TEST_CASE("UBJSON SAX parsing stops at every event")
@@ -2971,14 +2961,12 @@ TEST_CASE("UBJSON roundtrips" * doctest::skip())
                 CHECK(j1 == j2);
             }
 
-#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             {
                 INFO_WITH_TEMP(filename + ": uint8_t* and size");
                 json j2;
                 CHECK_NOTHROW(j2 = json::from_ubjson({packed.data(), packed.size()}));
                 CHECK(j1 == j2);
             }
-#endif
 
             {
                 INFO_WITH_TEMP(filename + ": output to output adapters");