Migrate REUSE metadata from deprecated .reuse/dep5 to REUSE.toml

reuse==6.2.0 (pinned in cmake/requirements/requirements-reuse.txt) warns
"'.reuse/dep5' is deprecated. You are recommended to instead use
REUSE.toml. Use `reuse convert-dep5` to convert." on every
ci_reuse_compliance run. A later reuse release that drops DEP5 support
would break that CI job outright.

Generate REUSE.toml from the 9 Files: stanzas with `reuse convert-dep5`
and remove .reuse/dep5. `reuse lint` still reports full compliance with
spec 3.3 (1268/1268 files with copyright and license information,
unchanged), and `reuse spdx` produces the same per-file copyright and
license entries as before the conversion.

Update the three places that referenced the old file: FILES.md now
documents REUSE.toml with a spec 3.3 link, README.md's REUSE section
names REUSE.toml, and the comment in gen_hedley_undef_check.cmake now
refers to REUSE.toml's blanket path = "**" rule.

Overlaps #4663, which adds an entry to .reuse/dep5; that PR will need to
move its entry into REUSE.toml when rebased on this.

#5716 item 4

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

.clang-tidy

@@ -1,9 +1,11 @@
-# TODO: portability-template-virtual-member-function is only removed to get the CI going. It has to be addressed at some point.
+# TODO: The first three checks are only removed to get the CI going. They have to be addressed at some point.
 # TODO: portability-avoid-pragma-once: should be fixed eventually
 
 Checks: '*,
 
          -portability-template-virtual-member-function,
+         -bugprone-use-after-move,
+         -hicpp-invalid-access-moved,
 
          -altera-id-dependent-backward-branch,
          -altera-struct-pack-align,

.github/workflows/macos.yml

@@ -71,3 +71,38 @@ jobs:
         run: cmake --build build --parallel 10
       - name: Test
         run: cd build ; ctest -j 10 --output-on-failure
+
+  swiftpm:
+    runs-on: macos-15
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+      - name: Check that Package.swift resolves without a deprecation warning
+        run: swift package dump-package
+      - name: Build the SwiftPM documentation example against this checkout
+        run: |
+          mkdir -p /tmp/json-swiftpm-consumer/Sources/MyLibrary
+          cp docs/mkdocs/docs/integration/swift/example.cpp /tmp/json-swiftpm-consumer/Sources/MyLibrary/example.cpp
+          cat > /tmp/json-swiftpm-consumer/Package.swift << EOF
+          // swift-tools-version: 5.9
+          import PackageDescription
+
+          let package = Package(
+              name: "MyPackage",
+              dependencies: [
+                  .package(path: "${{ github.workspace }}")
+              ],
+              targets: [
+                  .target(
+                      name: "MyLibrary",
+                      dependencies: [
+                          .product(name: "json", package: "json")
+                      ],
+                      publicHeadersPath: "."
+                  )
+              ]
+          )
+          EOF
+          cd /tmp/json-swiftpm-consumer
+          swift build

.reuse/dep5

@@ -1,40 +0,0 @@
-Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
-Upstream-Name: json
-Upstream-Contact: Niels Lohmann <mail@nlohmann.me>
-Source: https://github.com/nlohmann/json
-
-Files: *
-Copyright: 2013-2026 Niels Lohmann <https://nlohmann.me>
-License: MIT
-
-Files: include/nlohmann/thirdparty/hedley.hpp
-Copyright: 2016-2021 Evan Nemerson <evan@nemerson.com>
-License: CC0
-
-Files: include/nlohmann/detail/meta/cpp_future.hpp
-Copyright: 2013-2026 Niels Lohmann <https://nlohmann.me> and 2018 The Abseil Authors
-License: MIT AND Apache-2.0
-
-Files: tests/thirdparty/doctest/*
-Copyright: 2016-2023 Viktor Kirilov
-License: MIT
-
-Files: tests/thirdparty/fifo_map/*
-Copyright: 2015-2017 Niels Lohmann
-License: MIT
-
-Files: tests/thirdparty/Fuzzer/*
-Copyright: 2003-2022 LLVM Project.
-License: Apache-2.0
-
-Files: tests/thirdparty/imapdl/*
-Copyright: 2017 Georg Sauthoff <mail@gms.tf>
-License: GPL-3.0-only
-
-Files: tools/amalgamate/*
-Copyright: 2012 Erik Edlund <erik.edlund@32767.se>
-License: BSD-3-Clause
-
-Files: tools/gdb_pretty_printer/*
-Copyright: 2020 Hannes Domani <https://github.com/ssbssa>
-License: MIT

BUILD.bazel

@@ -77,6 +77,7 @@ cc_library(
     name = "singleheader-json",
     hdrs = [
         "single_include/nlohmann/json.hpp",
+        "single_include/nlohmann/json_fwd.hpp",
     ],
     includes = ["single_include"],
     visibility = ["//visibility:public"],

CITATION.cff

@@ -10,5 +10,5 @@ title: "JSON for Modern C++"
 version: 3.12.0
 date-released: 2025-04-07
 license: MIT
-repository-code: "https://github.com/nlohmann"
+repository-code: "https://github.com/nlohmann/json"
 url: https://json.nlohmann.me

CMakeLists.txt

@@ -42,8 +42,11 @@ endif()
 ## OPTIONS
 ##
 
+# Build the tests by default only for the main project and only if the tests
+# directory exists (the release archive json.tar.xz does not contain it).
 # VERSION_GREATER_EQUAL is not available in older CMake (< 3.7)
-if(${MAIN_PROJECT} AND (${CMAKE_VERSION} VERSION_EQUAL 3.13 OR ${CMAKE_VERSION} VERSION_GREATER 3.13))
+if(${MAIN_PROJECT} AND (${CMAKE_VERSION} VERSION_EQUAL 3.13 OR ${CMAKE_VERSION} VERSION_GREATER 3.13)
+   AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/tests/CMakeLists.txt")
     set(JSON_BuildTests_INIT ON)
 else()
     set(JSON_BuildTests_INIT OFF)

FILES.md

@@ -207,19 +207,19 @@ Further documentation:
 
 ## REUSE
 
-### `.reuse/dep5`
+### `REUSE.toml`
 
 The file defines the licenses of certain third-party components in the repository. The root `Makefile` contains a target `reuse` that checks for compliance.
 
 Further documentation:
 
-- [DEP5](https://reuse.software/spec-3.2/#dep5-deprecated)
+- [REUSE.toml](https://reuse.software/spec-3.3/#reusetoml)
 - [reuse command-line tool](https://pypi.org/project/reuse/)
 - [documentation of linting](https://reuse.readthedocs.io/en/stable/man/reuse-lint.html)
 - [REUSE](http://reuse.software)
 
 > [!IMPORTANT]
-> The filename `.reuse/dep5` is predetermined by REUSE. Alternatively, a `REUSE.toml` file can be used.
+> The filename `REUSE.toml` is predetermined by REUSE. Alternatively, a `.reuse/dep5` file (deprecated) can be used.
 
 ### `.reuse/templates`
 

Makefile

@@ -7,6 +7,9 @@
 # find GNU sed to use `-i` parameter
 SED:=$(shell command -v gsed || which sed)
 
+# find GNU tar to use `--sort` and `--pax-option` parameters
+TAR:=$(shell command -v gtar || which tar)
+
 
 ##########################################################################
 # source files
@@ -215,8 +218,8 @@ ChangeLog.md:
 # archive is created according to the advices of <https://reproducible-builds.org/docs/archives/>.
 json.tar.xz:
 	mkdir json
-	rsync -R $(shell find LICENSE.MIT nlohmann_json.natvis CMakeLists.txt cmake/*.in include single_include -type f) json
-	gtar --sort=name --mtime="@$(shell git log -1 --pretty=%ct)" --owner=0 --group=0 --numeric-owner --pax-option=exthdr.name=%d/PaxHeaders/%f,delete=atime,delete=ctime --create --file - json | xz --compress -9e --threads=2 - > json.tar.xz
+	rsync -R $(shell find LICENSE.MIT nlohmann_json.natvis CMakeLists.txt cmake/*.in include single_include src/modules -type f) json
+	$(TAR) --sort=name --mtime="@$(shell git log -1 --pretty=%ct)" --owner=0 --group=0 --numeric-owner --pax-option=exthdr.name=%d/PaxHeaders/%f,delete=atime,delete=ctime --create --file - json | xz --compress -9e --threads=2 - > json.tar.xz
 	rm -fr json
 
 # We use `-X` to make the resulting ZIP file reproducible, see

Package.swift

@@ -6,7 +6,7 @@ import PackageDescription
 let package = Package(
     name: "nlohmann-json",
      platforms: [
-        .iOS(.v12), .macOS(.v10_13), .tvOS(.v12), .watchOS(.v4), .visionOS(.v1)
+        .iOS(.v12), .macOS(.v10_13), .tvOS(.v12), .watchOS(.v9), .visionOS(.v1)
     ],
     products: [
         .library(name: "json", targets: ["json"])

README.md

@@ -1204,15 +1204,18 @@ language bindings, format converters, and the like. See the curated [Ecosystem](
 
 Though it's 2026 already, the support for C++11 is still a bit sparse. Currently, the following compilers are known to work:
 
-- GCC 4.8 - 14.2 (and possibly later)
-- Clang 3.4 - 21.0 (and possibly later)
-- Apple Clang 9.1 - 16.0 (and possibly later)
-- Intel C++ Compiler 17.0.2 (and possibly later)
-- Nvidia CUDA Compiler 11.0.221 (and possibly later)
-- Microsoft Visual C++ 2015 / Build Tools 14.0.25123.0 (and possibly later)
-- Microsoft Visual C++ 2017 / Build Tools 15.5.180.51428 (and possibly later)
-- Microsoft Visual C++ 2019 / Build Tools 16.3.1+1def00d3d (and possibly later)
-- Microsoft Visual C++ 2022 / Build Tools 19.30.30709.0 (and possibly later)
+- GCC 4.8 - 16.2 (and possibly later)
+- Clang 3.4 - 22.1 (and possibly later)
+- Apple Clang 15.0 - 21.0 (and possibly later)
+- Intel C++ Compiler Classic (icpc) 2021.10
+- Intel oneAPI DPC++/C++ Compiler (icpx) 2025.3 (and possibly later)
+- NVIDIA CUDA Compiler (nvcc) 11.8 - 12.6 (and possibly later)
+- NVIDIA HPC SDK C++ Compiler (nvc++) 25.5 (and possibly later)
+- Microsoft Visual C++ 2015 / MSVC 19.0 (and possibly later)
+- Microsoft Visual C++ 2017 / MSVC 19.16 (and possibly later)
+- Microsoft Visual C++ 2019 / MSVC 19.29 (and possibly later)
+- Microsoft Visual C++ 2022 / MSVC 19.44 (and possibly later)
+- Microsoft Visual C++ 2026 / MSVC 19.51 (and possibly later)
 
 I would be happy to learn about other compilers/versions.
 
@@ -1402,7 +1405,7 @@ The library is compliant to version 3.3 of the [**REUSE specification**](https:/
 
 - Every source file contains an SPDX copyright header.
 - The full text of all licenses used in the repository can be found in the `LICENSES` folder.
-- File `.reuse/dep5` contains an overview of all files' copyrights and licenses.
+- File `REUSE.toml` contains an overview of all files' copyrights and licenses.
 - Run `pipx run reuse lint` to verify the project's REUSE compliance and `pipx run reuse spdx` to generate a SPDX SBOM.
 
 ## Contact

REUSE.toml

@@ -0,0 +1,58 @@
+version = 1
+SPDX-PackageName = "json"
+SPDX-PackageSupplier = "Niels Lohmann <mail@nlohmann.me>"
+SPDX-PackageDownloadLocation = "https://github.com/nlohmann/json"
+
+[[annotations]]
+path = "**"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2013-2026 Niels Lohmann <https://nlohmann.me>"
+SPDX-License-Identifier = "MIT"
+
+[[annotations]]
+path = "include/nlohmann/thirdparty/hedley.hpp"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2016-2021 Evan Nemerson <evan@nemerson.com>"
+SPDX-License-Identifier = "CC0"
+
+[[annotations]]
+path = "include/nlohmann/detail/meta/cpp_future.hpp"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2013-2026 Niels Lohmann <https://nlohmann.me> and 2018 The Abseil Authors"
+SPDX-License-Identifier = "MIT AND Apache-2.0"
+
+[[annotations]]
+path = "tests/thirdparty/doctest/**"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2016-2023 Viktor Kirilov"
+SPDX-License-Identifier = "MIT"
+
+[[annotations]]
+path = "tests/thirdparty/fifo_map/**"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2015-2017 Niels Lohmann"
+SPDX-License-Identifier = "MIT"
+
+[[annotations]]
+path = "tests/thirdparty/Fuzzer/**"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2003-2022 LLVM Project."
+SPDX-License-Identifier = "Apache-2.0"
+
+[[annotations]]
+path = "tests/thirdparty/imapdl/**"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2017 Georg Sauthoff <mail@gms.tf>"
+SPDX-License-Identifier = "GPL-3.0-only"
+
+[[annotations]]
+path = "tools/amalgamate/**"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2012 Erik Edlund <erik.edlund@32767.se>"
+SPDX-License-Identifier = "BSD-3-Clause"
+
+[[annotations]]
+path = "tools/gdb_pretty_printer/**"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2020 Hannes Domani <https://github.com/ssbssa>"
+SPDX-License-Identifier = "MIT"

cmake/scripts/gen_bazel_build_file.cmake

@@ -48,6 +48,7 @@ cc_library(
     name = "singleheader-json",
     hdrs = [
         "single_include/nlohmann/json.hpp",
+        "single_include/nlohmann/json_fwd.hpp",
     ],
     includes = ["single_include"],
     visibility = ["//visibility:public"],

cmake/scripts/gen_hedley_undef_check.cmake

@@ -64,7 +64,7 @@ if(MODE STREQUAL "undef")
     # recipe is self-contained and its output is byte-stable across reruns.
     # The embedded SPDX tags below are part of the *generated* file's
     # content, not a REUSE header for this .cmake script itself (which is
-    # already covered by the blanket "Files: *" rule in .reuse/dep5) -- keep
+    # already covered by the blanket path = "**" rule in REUSE.toml) -- keep
     # them wrapped in REUSE-IgnoreStart/End so `reuse lint` does not try to
     # parse "MIT\n")" as this file's own SPDX-License-Identifier value.
     # REUSE-IgnoreStart

docs/mkdocs/docs/api/basic_json/meta.md

@@ -13,7 +13,7 @@ JSON object holding version information
 
 | key         | description                                                                                                                                                                                                                                                                    |
 |-------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| `compiler`  | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `hp`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version). |
+| `compiler`  | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version). On HP aCC compilers, `compiler` is instead the plain string `hp`. |
 | `copyright` | The copyright line for the library as string.                                                                                                                                                                                                                                  |
 | `name`      | The name of the library as string.                                                                                                                                                                                                                                             |
 | `platform`  | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`.                                                                                                                                                                             |

docs/mkdocs/docs/integration/cmake.md

@@ -125,7 +125,7 @@ automatically download a release as a dependency at configure time.
 
 ### `JSON_BuildTests`
 
-Build the unit tests when [`BUILD_TESTING`](https://cmake.org/cmake/help/latest/command/enable_testing.html) is enabled. This option is `ON` by default if the library's CMake project is the top project. That is, when integrating the library as described above, the test suite is not built unless explicitly switched on with this option.
+Build the unit tests when [`BUILD_TESTING`](https://cmake.org/cmake/help/latest/command/enable_testing.html) is enabled. This option is `ON` by default if the library's CMake project is the top project and the `tests` directory exists (the release archive `json.tar.xz` does not contain it). That is, when integrating the library as described above, the test suite is not built unless explicitly switched on with this option.
 
 ### `JSON_CI`
 

docs/mkdocs/docs/integration/package_managers.md

@@ -443,6 +443,30 @@ installed by adding the `-DJSON_MultipleHeaders=ON` flag (i.e., `cget install nl
     - :octicons-file-24: File issues at the [library issue tracker](https://github.com/nlohmann/json/issues)
     - :octicons-question-24: [Xcode documentation](https://developer.apple.com/documentation/xcode/adding-package-dependencies-to-your-app)
 
+The `json` target's public headers live at `single_include/nlohmann`, so a consumer must write `#include <json.hpp>` rather than the
+`#include <nlohmann/json.hpp>` form used elsewhere in this documentation. The `json` target also ships only headers, and SwiftPM/Xcode
+expect every library target to produce an object file to link against; without one, linking a consumer fails with a missing `json.o`
+([#4650](https://github.com/nlohmann/json/issues/4650)). The workaround is to add at least one `.cpp` file of your own to the target
+that depends on `json`.
+
+??? example
+
+    1. Create the following files:
+
+        ```swift title="Package.swift"
+        --8<-- "integration/swift/Package.swift"
+        ```
+
+        ```cpp title="Sources/MyLibrary/example.cpp"
+        --8<-- "integration/swift/example.cpp"
+        ```
+
+    2. Build
+
+        ```shell
+        swift build
+        ```
+
 ## NuGet
 
 !!! abstract "Summary"

docs/mkdocs/docs/integration/swift/Package.swift

@@ -0,0 +1,20 @@
+// swift-tools-version: 5.9
+import PackageDescription
+
+let package = Package(
+    name: "MyPackage",
+    dependencies: [
+        .package(url: "https://github.com/nlohmann/json.git", from: "3.12.0")
+    ],
+    targets: [
+        // the C++ target that uses nlohmann/json
+        .target(
+            name: "MyLibrary",
+            dependencies: [
+                .product(name: "json", package: "json")
+            ],
+            // works around missing public headers in MyLibrary; not related to nlohmann/json
+            publicHeadersPath: "."
+        )
+    ]
+)

docs/mkdocs/docs/integration/swift/example.cpp

@@ -0,0 +1,8 @@
+// MyLibrary must contain at least one .cpp file, or SwiftPM/Xcode will
+// not build a usable "json" library to link against (see nlohmann/json#4650)
+#include <json.hpp>
+
+nlohmann::json example()
+{
+    return nlohmann::json::meta();
+}

include/nlohmann/detail/conversions/from_json.hpp

@@ -353,7 +353,7 @@ template < typename BasicJsonType, typename T, std::size_t... Idx >
 std::array<T, sizeof...(Idx)> from_json_inplace_array_impl(BasicJsonType&& j,
                      identity_tag<std::array<T, sizeof...(Idx)>> /*unused*/, index_sequence<Idx...> /*unused*/)
 {
-    return { { j.at(Idx).template get<T>()... } };
+    return { { std::forward<BasicJsonType>(j).at(Idx).template get<T>()... } };
 }
 
 template < typename BasicJsonType, typename T, std::size_t N >
@@ -502,7 +502,7 @@ using tuple_type = std::tuple < decltype(from_json_tuple_get_impl(std::declval<B
 template<std::size_t PTagValue, typename... Args, typename BasicJsonType, std::size_t... Idx>
 tuple_type<PTagValue, BasicJsonType, Args...> from_json_tuple_impl_base(BasicJsonType&& j, index_sequence<Idx...> /*unused*/)
 {
-    return tuple_type<PTagValue, BasicJsonType, Args...>(from_json_tuple_get_impl(j.at(Idx), detail::identity_tag<Args> {}, detail::priority_tag<PTagValue> {})...);
+    return tuple_type<PTagValue, BasicJsonType, Args...>(from_json_tuple_get_impl(std::forward<BasicJsonType>(j).at(Idx), detail::identity_tag<Args> {}, detail::priority_tag<PTagValue> {})...);
 }
 
 template<std::size_t PTagValue, typename BasicJsonType>
@@ -514,8 +514,8 @@ std::tuple<> from_json_tuple_impl_base(BasicJsonType& /*unused*/, index_sequence
 template < typename BasicJsonType, class A1, class A2 >
 std::pair<A1, A2> from_json_tuple_impl(BasicJsonType&& j, identity_tag<std::pair<A1, A2>> /*unused*/, priority_tag<0> /*unused*/)
 {
-    return {j.at(0).template get<A1>(),
-            j.at(1).template get<A2>()};
+    return {std::forward<BasicJsonType>(j).at(0).template get<A1>(),
+            std::forward<BasicJsonType>(j).at(1).template get<A2>()};
 }
 
 template<typename BasicJsonType, typename A1, typename A2>

include/nlohmann/detail/input/input_adapters.hpp

@@ -763,7 +763,6 @@ struct container_input_adapter_factory< ContainerType,
 
            static adapter_type create(ContainerType&& container)
 {
-    // NOLINTNEXTLINE(bugprone-use-after-move,hicpp-invalid-access-moved) forwarded twice on purpose, so begin() and end() see the same value category and yield matching iterator types
     return input_adapter(begin(std::forward<ContainerType>(container)), end(std::forward<ContainerType>(container)));
 }
        };

include/nlohmann/detail/string_concat.hpp

@@ -39,6 +39,7 @@ inline std::size_t concat_length(const char /*c*/, const Args& ... rest)
 template<typename... Args>
 inline std::size_t concat_length(const char* cstr, const Args& ... rest)
 {
+    // cppcheck-suppress ignoredReturnValue
     return ::strlen(cstr) + concat_length(rest...);
 }
 

include/nlohmann/ordered_map.hpp

@@ -70,41 +70,14 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
         return *this;
     }
 
-private:
-    /// @brief find the entry for @a key, for either constness of @a self
-    /// @note the single place that performs the linear key search
-    template<typename Self, typename KeyType>
-    static auto find_impl(Self& self, KeyType&& key) -> decltype(self.begin())
-    {
-        for (auto it = self.begin(); it != self.end(); ++it)
-        {
-            if (self.m_compare(it->first, key))
-            {
-                return it;
-            }
-        }
-        return self.end();
-    }
-
-    /// @brief remove the entry @a it points to, preserving order
-    /// @note keys are not movable, so the tail is destroyed and re-constructed in place
-    void erase_at(iterator it)
-    {
-        for (auto next = it; ++next != this->end(); ++it)
-        {
-            it->~value_type(); // Destroy but keep allocation
-            new (&*it) value_type{std::move(*next)};
-        }
-        Container::pop_back();
-    }
-
-public:
     std::pair<iterator, bool> emplace(const key_type& key, T&& t)
     {
-        const auto it = find_impl(*this, key);
-        if (it != this->end())
+        for (auto it = this->begin(); it != this->end(); ++it)
         {
-            return {it, false};
+            if (m_compare(it->first, key))
+            {
+                return {it, false};
+            }
         }
         Container::emplace_back(key, std::forward<T>(t));
         return {std::prev(this->end()), true};
@@ -114,10 +87,12 @@ public:
                  detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
     std::pair<iterator, bool> emplace(KeyType && key, T && t)
     {
-        const auto it = find_impl(*this, key);
-        if (it != this->end())
+        for (auto it = this->begin(); it != this->end(); ++it)
         {
-            return {it, false};
+            if (m_compare(it->first, key))
+            {
+                return {it, false};
+            }
         }
         Container::emplace_back(std::forward<KeyType>(key), std::forward<T>(t));
         return {std::prev(this->end()), true};
@@ -149,55 +124,75 @@ public:
 
     T& at(const key_type& key)
     {
-        const auto it = find_impl(*this, key);
-        if (it == this->end())
+        for (auto it = this->begin(); it != this->end(); ++it)
         {
-            JSON_THROW(std::out_of_range("key not found"));
+            if (m_compare(it->first, key))
+            {
+                return it->second;
+            }
         }
-        return it->second;
+
+        JSON_THROW(std::out_of_range("key not found"));
     }
 
     template<class KeyType, detail::enable_if_t<
                  detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
     T & at(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
     {
-        const auto it = find_impl(*this, key);
-        if (it == this->end())
+        for (auto it = this->begin(); it != this->end(); ++it)
         {
-            JSON_THROW(std::out_of_range("key not found"));
+            if (m_compare(it->first, key))
+            {
+                return it->second;
+            }
         }
-        return it->second;
+
+        JSON_THROW(std::out_of_range("key not found"));
     }
 
     const T& at(const key_type& key) const
     {
-        const auto it = find_impl(*this, key);
-        if (it == this->end())
+        for (auto it = this->begin(); it != this->end(); ++it)
         {
-            JSON_THROW(std::out_of_range("key not found"));
+            if (m_compare(it->first, key))
+            {
+                return it->second;
+            }
         }
-        return it->second;
+
+        JSON_THROW(std::out_of_range("key not found"));
     }
 
     template<class KeyType, detail::enable_if_t<
                  detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
     const T & at(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
     {
-        const auto it = find_impl(*this, key);
-        if (it == this->end())
+        for (auto it = this->begin(); it != this->end(); ++it)
         {
-            JSON_THROW(std::out_of_range("key not found"));
+            if (m_compare(it->first, key))
+            {
+                return it->second;
+            }
         }
-        return it->second;
+
+        JSON_THROW(std::out_of_range("key not found"));
     }
 
     size_type erase(const key_type& key)
     {
-        const auto it = find_impl(*this, key);
-        if (it != this->end())
+        for (auto it = this->begin(); it != this->end(); ++it)
         {
-            erase_at(it);
-            return 1;
+            if (m_compare(it->first, key))
+            {
+                // Since we cannot move const Keys, re-construct them in place
+                for (auto next = it; ++next != this->end(); ++it)
+                {
+                    it->~value_type(); // Destroy but keep allocation
+                    new (&*it) value_type{std::move(*next)};
+                }
+                Container::pop_back();
+                return 1;
+            }
         }
         return 0;
     }
@@ -206,11 +201,19 @@ public:
                  detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
     size_type erase(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
     {
-        const auto it = find_impl(*this, key);
-        if (it != this->end())
+        for (auto it = this->begin(); it != this->end(); ++it)
         {
-            erase_at(it);
-            return 1;
+            if (m_compare(it->first, key))
+            {
+                // Since we cannot move const Keys, re-construct them in place
+                for (auto next = it; ++next != this->end(); ++it)
+                {
+                    it->~value_type(); // Destroy but keep allocation
+                    new (&*it) value_type{std::move(*next)};
+                }
+                Container::pop_back();
+                return 1;
+            }
         }
         return 0;
     }
@@ -275,38 +278,80 @@ public:
 
     size_type count(const key_type& key) const
     {
-        return find_impl(*this, key) != this->end() ? 1 : 0;
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (m_compare(it->first, key))
+            {
+                return 1;
+            }
+        }
+        return 0;
     }
 
     template<class KeyType, detail::enable_if_t<
                  detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
     size_type count(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
     {
-        return find_impl(*this, key) != this->end() ? 1 : 0;
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (m_compare(it->first, key))
+            {
+                return 1;
+            }
+        }
+        return 0;
     }
 
     iterator find(const key_type& key)
     {
-        return find_impl(*this, key);
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (m_compare(it->first, key))
+            {
+                return it;
+            }
+        }
+        return Container::end();
     }
 
     template<class KeyType, detail::enable_if_t<
                  detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
     iterator find(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
     {
-        return find_impl(*this, key);
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (m_compare(it->first, key))
+            {
+                return it;
+            }
+        }
+        return Container::end();
     }
 
     const_iterator find(const key_type& key) const
     {
-        return find_impl(*this, key);
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (m_compare(it->first, key))
+            {
+                return it;
+            }
+        }
+        return Container::end();
     }
 
     template<class KeyType, detail::enable_if_t<
                  detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
     const_iterator find(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
     {
-        return find_impl(*this, key);
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (m_compare(it->first, key))
+            {
+                return it;
+            }
+        }
+        return Container::end();
     }
 
     std::pair<iterator, bool> insert( value_type&& value )
@@ -316,10 +361,12 @@ public:
 
     std::pair<iterator, bool> insert( const value_type& value )
     {
-        const auto it = find_impl(*this, value.first);
-        if (it != this->end())
+        for (auto it = this->begin(); it != this->end(); ++it)
         {
-            return {it, false};
+            if (m_compare(it->first, value.first))
+            {
+                return {it, false};
+            }
         }
         Container::push_back(value);
         return {--this->end(), true};

tests/src/unit-class_parser.cpp

@@ -2525,10 +2525,12 @@ TEST_CASE("diagnostic positions: value lifetime, input adapters, and SAX")
 
         SECTION("move constructor resets the moved-from value to npos")
         {
-            // basic_json(basic_json&&) (json.hpp, around line 1944) copies
+            // basic_json(basic_json&&) (json.hpp, around line 1265) copies
             // other's start_position/end_position into *this and then resets
-            // other's to npos. Only the top-level moved-from value is
-            // affected; its (moved-away) children are gone along with it.
+            // other's to npos (see the cppcheck-suppress[accessForwarded]
+            // annotation there, which flags this reset as worth a second
+            // look). Only the top-level moved-from value is affected; its
+            // (moved-away) children are gone along with it.
             const std::string s = R"({"a":1,"b":[1,2,3]})";
             json a = json::parse(s);
             const auto a_start = a.start_pos();

tests/src/unit-modifiers.cpp

@@ -618,49 +618,6 @@ TEST_CASE("modifiers")
             }
         }
 
-        SECTION("rvalue at position moves rather than copies")
-        {
-            // regression test: insert(pos, basic_json&&) used to forward to
-            // insert(pos, const basic_json&) because the named rvalue
-            // reference parameter is itself an lvalue, so it always
-            // deep-copied its argument instead of moving it
-            json j_big = std::string(1000, 'x');
-            const auto* const original_buffer = j_big.get_ref<const std::string&>().data();
-
-            auto it = j_array.insert(j_array.begin(), std::move(j_big));
-            CHECK(j_array.size() == 5);
-            CHECK(*it == json(std::string(1000, 'x')));
-            CHECK((*it).get_ref<const std::string&>().data() == original_buffer);
-
-            // the moved-from value is null, the same as after push_back(&&)
-            CHECK(j_big.is_null()); // NOLINT(bugprone-use-after-move,hicpp-invalid-access-moved)
-        }
-
-        SECTION("self-aliasing insertion")
-        {
-            SECTION("without reallocation")
-            {
-                json j_self = {1, 2, 3, 4};
-                j_self.get_ref<json::array_t&>().reserve(j_self.size() + 1);
-
-                auto it = j_self.insert(j_self.begin(), std::move(j_self[1]));
-                CHECK(j_self.size() == 5);
-                CHECK(*it == json(2));
-                CHECK(j_self == json({2, 1, nullptr, 3, 4}));
-            }
-
-            SECTION("with reallocation")
-            {
-                json j_self = {1, 2, 3, 4};
-                j_self.get_ref<json::array_t&>().shrink_to_fit();
-
-                auto it = j_self.insert(j_self.begin(), std::move(j_self[1]));
-                CHECK(j_self.size() == 5);
-                CHECK(*it == json(2));
-                CHECK(j_self == json({2, 1, nullptr, 3, 4}));
-            }
-        }
-
         SECTION("copies at position")
         {
             SECTION("insert before begin()")