Drop the version history note for a bug that was never released

The regression came from #5390, which is not in any release. Addresses review comment by @gregmarr.

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

.github/workflows/macos.yml

@@ -71,38 +71,3 @@ 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

@@ -0,0 +1,40 @@
+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

@@ -77,7 +77,6 @@ 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/json"
+repository-code: "https://github.com/nlohmann"
 url: https://json.nlohmann.me

CMakeLists.txt

@@ -42,11 +42,8 @@ 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 ${CMAKE_VERSION} VERSION_GREATER 3.13)
-   AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/tests/CMakeLists.txt")
+if(${MAIN_PROJECT} AND (${CMAKE_VERSION} VERSION_EQUAL 3.13 OR ${CMAKE_VERSION} VERSION_GREATER 3.13))
     set(JSON_BuildTests_INIT ON)
 else()
     set(JSON_BuildTests_INIT OFF)

FILES.md

@@ -207,19 +207,19 @@ Further documentation:
 
 ## REUSE
 
-### `REUSE.toml`
+### `.reuse/dep5`
 
 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:
 
-- [REUSE.toml](https://reuse.software/spec-3.3/#reusetoml)
+- [DEP5](https://reuse.software/spec-3.2/#dep5-deprecated)
 - [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.toml` is predetermined by REUSE. Alternatively, a `.reuse/dep5` file (deprecated) can be used.
+> The filename `.reuse/dep5` is predetermined by REUSE. Alternatively, a `REUSE.toml` file can be used.
 
 ### `.reuse/templates`
 

Makefile

@@ -7,9 +7,6 @@
 # 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
@@ -218,8 +215,8 @@ 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 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
+	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
 	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(.v9), .visionOS(.v1)
+        .iOS(.v12), .macOS(.v10_13), .tvOS(.v12), .watchOS(.v4), .visionOS(.v1)
     ],
     products: [
         .library(name: "json", targets: ["json"])

README.md

@@ -1204,18 +1204,15 @@ 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 - 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)
+- 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)
 
 I would be happy to learn about other compilers/versions.
 
@@ -1405,7 +1402,7 @@ 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.toml` contains an overview of all files' copyrights and licenses.
+- File `.reuse/dep5` 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

@@ -1,58 +0,0 @@
-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

@@ -48,7 +48,6 @@ 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 path = "**" rule in REUSE.toml) -- keep
+    # already covered by the blanket "Files: *" rule in .reuse/dep5) -- 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/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 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.
+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.
 
 ### `JSON_CI`
 

docs/mkdocs/docs/integration/package_managers.md

@@ -443,30 +443,6 @@ 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

@@ -1,20 +0,0 @@
-// 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

@@ -1,8 +0,0 @@
-// 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/json.hpp

@@ -1307,15 +1307,65 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     */
     template<bool Ordered>
     static compare_result compare_leaves(const_reference lhs, const_reference rhs) noexcept
+    {
+        return compare_leaves(lhs, rhs, std::integral_constant<bool, Ordered> {});
+    }
+
+    /// @brief compare two leaves that are only being checked for equality
+    static compare_result compare_leaves(const_reference lhs, const_reference rhs, std::false_type /*ordered*/) noexcept
     {
         if (lhs == rhs)
         {
             return compare_result::equal;
         }
 
-        return order_leaves(lhs, rhs, std::integral_constant<bool, Ordered> {});
+        return order_leaves(lhs, rhs, std::false_type {});
     }
 
+#if JSON_HAS_THREE_WAY_COMPARISON
+    /*!
+    @brief compare two leaves that are being ordered, for operator<=>
+
+    Reached only from operator<=>, so the leaves must be classified exactly
+    as operator<=> classifies them - which is not the same as asking
+    == and then order_leaves(), the way the other overload does it. The two
+    disagree on a binary value: == also compares the subtype, but <=> compares
+    only the bytes, through std::vector<std::uint8_t>::operator<=>. Using <=>
+    itself here keeps a leaf pair classified the same way regardless of how
+    deep it is nested - == first would again call operator<=> a level down
+    through order_leaves(), but call it after a mismatching == already ended
+    the comparison for a pair that <=> alone would still call equivalent.
+    */
+    static compare_result compare_leaves(const_reference lhs, const_reference rhs, std::true_type /*ordered*/) noexcept
+    {
+        const std::partial_ordering order = lhs <=> rhs; // *NOPAD*
+        if (order == 0)
+        {
+            return compare_result::equal;
+        }
+        if (order < 0)
+        {
+            return compare_result::less;
+        }
+        if (order > 0)
+        {
+            return compare_result::greater;
+        }
+        return compare_result::unordered;
+    }
+#else
+    /// @brief compare two leaves that are being ordered, for operator<
+    static compare_result compare_leaves(const_reference lhs, const_reference rhs, std::true_type /*ordered*/) noexcept
+    {
+        if (lhs == rhs)
+        {
+            return compare_result::equal;
+        }
+
+        return order_leaves(lhs, rhs, std::true_type {});
+    }
+#endif
+
     /*!
     @brief compare two object keys
 

single_include/nlohmann/json.hpp

@@ -27388,15 +27388,65 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     */
     template<bool Ordered>
     static compare_result compare_leaves(const_reference lhs, const_reference rhs) noexcept
+    {
+        return compare_leaves(lhs, rhs, std::integral_constant<bool, Ordered> {});
+    }
+
+    /// @brief compare two leaves that are only being checked for equality
+    static compare_result compare_leaves(const_reference lhs, const_reference rhs, std::false_type /*ordered*/) noexcept
     {
         if (lhs == rhs)
         {
             return compare_result::equal;
         }
 
-        return order_leaves(lhs, rhs, std::integral_constant<bool, Ordered> {});
+        return order_leaves(lhs, rhs, std::false_type {});
     }
 
+#if JSON_HAS_THREE_WAY_COMPARISON
+    /*!
+    @brief compare two leaves that are being ordered, for operator<=>
+
+    Reached only from operator<=>, so the leaves must be classified exactly
+    as operator<=> classifies them - which is not the same as asking
+    == and then order_leaves(), the way the other overload does it. The two
+    disagree on a binary value: == also compares the subtype, but <=> compares
+    only the bytes, through std::vector<std::uint8_t>::operator<=>. Using <=>
+    itself here keeps a leaf pair classified the same way regardless of how
+    deep it is nested - == first would again call operator<=> a level down
+    through order_leaves(), but call it after a mismatching == already ended
+    the comparison for a pair that <=> alone would still call equivalent.
+    */
+    static compare_result compare_leaves(const_reference lhs, const_reference rhs, std::true_type /*ordered*/) noexcept
+    {
+        const std::partial_ordering order = lhs <=> rhs; // *NOPAD*
+        if (order == 0)
+        {
+            return compare_result::equal;
+        }
+        if (order < 0)
+        {
+            return compare_result::less;
+        }
+        if (order > 0)
+        {
+            return compare_result::greater;
+        }
+        return compare_result::unordered;
+    }
+#else
+    /// @brief compare two leaves that are being ordered, for operator<
+    static compare_result compare_leaves(const_reference lhs, const_reference rhs, std::true_type /*ordered*/) noexcept
+    {
+        if (lhs == rhs)
+        {
+            return compare_result::equal;
+        }
+
+        return order_leaves(lhs, rhs, std::true_type {});
+    }
+#endif
+
     /*!
     @brief compare two object keys
 

tests/src/unit-comparison.cpp

@@ -952,3 +952,51 @@ TEST_CASE("containers are compared element by element")
         }
     }
 }
+
+#if JSON_HAS_THREE_WAY_COMPARISON
+// JSON_HAS_CPP_20 (do not remove; see note at top of file)
+TEST_CASE("operator<=> of binary values with a different subtype does not depend on nesting depth")
+{
+    // #5654: std::vector<std::uint8_t>::operator<=>, which the binary type's
+    // own operator<=> uses, ignores the subtype that operator== checks. So a
+    // pair of binary values with the same bytes but a different subtype is
+    // unequal, yet <=>-equivalent - the same inconsistency between == and <=>
+    // that a NaN has. Within the nesting bound, an array compares itself
+    // with std::vector's own operator<=>, which treats an equivalent pair as
+    // undecided and lets the next element decide, same as
+    // std::lexicographical_compare_three_way does. Past the bound,
+    // compare_iteratively<true>() takes over and must classify the pair the
+    // same way, or the result of operator<=> - and of <, which C++20 derives
+    // from it - depends on how deeply the values are nested.
+    const json a = json::array({json::binary({1}, 1), 1});
+    const json b = json::array({json::binary({1}, 2), 2});
+
+    // the root inconsistency: unequal, yet <=>-equivalent
+    CHECK_FALSE(a[0] == b[0]);
+    CHECK((a[0] <=> b[0]) == std::partial_ordering::equivalent); // *NOPAD*
+
+    const auto deep = [](const json & j, const std::size_t depth)
+    {
+        json result = j;
+        for (std::size_t i = 0; i < depth; ++i)
+        {
+            result = json::array({std::move(result)});
+        }
+        return result;
+    };
+
+    // 127 levels stay within nesting_depth_limit() (128); 128 and 200 do not,
+    // and must still agree with the levels that do
+    for (const std::size_t depth : std::vector<std::size_t> {0, 127, 128, 200})
+    {
+        CAPTURE(depth);
+        const json x = deep(a, depth);
+        const json y = deep(b, depth);
+        CHECK((x <=> y) == std::partial_ordering::less); // *NOPAD*
+        CHECK((y <=> x) == std::partial_ordering::greater); // *NOPAD*
+        CHECK(x < y);
+        CHECK(y > x);
+        CHECK_FALSE(y < x);
+    }
+}
+#endif