Test for EMPTY and MEMBERS so -Wunused-macros accepts them

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Keep user macros named EMPTY or MEMBERS out of the member-count dispatch
2026-09-25 09:20:32 +00:00 · 2026-09-24 09:38:18 +02:00 · 2026-09-23 20:28:37 +02:00 · 2026-08-20 09:01:11 +02:00 · 2026-08-19 23:05:45 +02:00 · 2026-08-19 21:03:08 +02:00
219 changed files with 5979 additions and 25982 deletions
@@ -108,9 +108,7 @@ The tests are located in [`tests/src/unit-*.cpp`](https://github.com/nlohmann/js
 are structured along the features of the library or the nature of the tests. Usually, it should be clear from the
 context which existing file needs to be extended, and only very few cases require creating new test files.

-When fixing a bug, edit `unit-regression3.cpp` and add a section referencing the fixed issue.
-`unit-regression2.cpp` holds the older tests; the two files exist because a single one grew large enough for the
-MinGW linker to fail relocating it, so please keep adding to the smaller file rather than growing the larger one.
+When fixing a bug, edit `unit-regression2.cpp` and add a section referencing the fixed issue.

 #### Exceptions

@@ -158,15 +156,6 @@ make amalgamate
 Running `make amalgamate` will also apply automatic formatting to the source files using
 [`Artistic Style`](https://astyle.sourceforge.net/). This formatting may modify your source files in-place. Be certain to review and commit any changes to avoid unintended formatting diffs in commits.

-If you add, rename, or remove a header in `include/nlohmann`, also regenerate the header list in
-[`BUILD.bazel`](https://github.com/nlohmann/json/blob/develop/BUILD.bazel) (requires CMake) by executing:
-
-```shell
-make BUILD.bazel
-```
-
-The amalgamation check in CI fails if any of these generated files is out of date.
-
 ## Recommended documentation

 - The library’s [README file](https://github.com/nlohmann/json/blob/master/README.md) is an excellent starting point to
@@ -2,7 +2,6 @@

 - [ ] The changes are described in detail, both the what and why.
 - [ ] If applicable, an [existing issue](https://github.com/nlohmann/json/issues) is referenced.
- [ ] If applicable, a fixed [OSS-Fuzz](https://issues.oss-fuzz.com) issue is referenced as `OSS-Fuzz: <id>` (see [fuzz testing](https://github.com/nlohmann/json/blob/develop/tests/fuzzing.md#handling-oss-fuzz-reports)).
 - [ ] The [Code coverage](https://coveralls.io/github/nlohmann/json) remained at 100%. A test case for every new line of code.
 - [ ] If applicable, the [documentation](https://json.nlohmann.me) is updated.
 - [ ] The source code is amalgamated by running `make amalgamate`.
@@ -15,14 +15,6 @@ guidance.

 For vulnerabilities in third-party dependencies or modules, please report them directly to the respective maintainers.

-## Unofficial packages
-
-This project does not publish an official npm package. The npm package
-[`nlohmann-json`](https://www.npmjs.com/package/nlohmann-json) (or similarly named packages) is not maintained or
-endorsed by this project. See the
-[package managers documentation](https://json.nlohmann.me/integration/package_managers/#npm) for supported
-integration options.
-
 ## Additional Resources

 - Explore security-related topics and contribute to tools and projects through
@@ -29,27 +29,6 @@ labels:
  files:
    - ".github/external_ci/.*"

- label: "CI"
-  files:
-    - ".github/(dependabot|labeler)\\.yml"
-
- label: "aspect: binary formats"
-  files:
-    - "include/nlohmann/detail/input/binary_reader\\.hpp"
-    - "include/nlohmann/detail/output/binary_writer\\.hpp"
-    - "tests/src/unit-(bson|cbor|msgpack|ubjson|bjdata|binary_formats)"
-    - "tests/src/fuzzer-parse_(bson|cbor|msgpack|ubjson|bjdata)"
-    - "docs/mkdocs/docs/features/binary_formats/"
-    - "docs/mkdocs/docs/(api/basic_json|examples)/(to|from)_(bson|cbor|msgpack|ubjson|bjdata)"
-
- label: "aspect: binary formats"
-  title: "(?i)(bson|cbor|msgpack|messagepack|ubjson|bjdata|binary format)"
-
- label: "python"
-  files:
-    - "\\.py$"
-    - "requirements[^/]*\\.txt$"
-
 - label: "S"
  size-below: 10
 - label: "M"
@@ -11,7 +11,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -34,19 +34,19 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

      - name: Checkout pull request
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          path: main
          ref: ${{ github.event.pull_request.head.sha }}
          persist-credentials: false

      - name: Checkout tools
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          path: tools
          ref: develop
@@ -57,31 +57,18 @@ jobs:
          python3 -mvenv venv
          venv/bin/pip3 install -r $MAIN_DIR/tools/astyle/requirements.txt

-      - name: Regenerate amalgamation, formatting, and BUILD.bazel
+      - name: Regenerate amalgamation and formatting
        run: |
          cd $MAIN_DIR

          python3 $TOOL_DIR/amalgamate.py -c $TOOL_DIR/config_json.json -s .
          python3 $TOOL_DIR/amalgamate.py -c $TOOL_DIR/config_json_fwd.json -s .

-          # the header list of the Bazel "json" target must match the files in include/
-          cmake -P cmake/scripts/gen_bazel_build_file.cmake
-
          ${{ github.workspace }}/venv/bin/astyle --project=tools/astyle/.astylerc --suffix=none --quiet \
            $INCLUDE_DIR/json.hpp $INCLUDE_DIR/json_fwd.hpp

-          # fail loudly if a directory is renamed or removed: find would only warn
-          # about the missing path and silently drop its files from the check
-          SOURCE_DIRS="docs/mkdocs/docs/examples include tests"
-          for DIR in $SOURCE_DIRS; do
-            if [ ! -d "$DIR" ]; then
-              echo "::error::source directory '$DIR' does not exist"
-              exit 1
-            fi
-          done
-
          ${{ github.workspace }}/venv/bin/astyle --project=tools/astyle/.astylerc --suffix=none --quiet \
-            $(find $SOURCE_DIRS -type f \( -name '*.hpp' -o -name '*.cpp' -o -name '*.cu' \) -not -path 'tests/thirdparty/*' -not -path 'tests/abi/include/nlohmann/*' | sort)
+            $(find docs/examples include tests -type f \( -name '*.hpp' -o -name '*.cpp' -o -name '*.cu' \) -not -path 'tests/thirdparty/*' -not -path 'tests/abi/include/nlohmann/*' | sort)

      - name: Build patch and check for differences
        id: diff
@@ -90,7 +77,7 @@ jobs:
          mkdir -p ${{ github.workspace }}/patch
          git diff --patch --no-color > ${{ github.workspace }}/patch/amalgamation.patch
          if [ -s ${{ github.workspace }}/patch/amalgamation.patch ]; then
-            echo "The source code has not been amalgamated/formatted correctly or BUILD.bazel is out of date. Diff:"
+            echo "The source code has not been amalgamated/formatted correctly. Diff:"
            cat ${{ github.workspace }}/patch/amalgamation.patch
            echo "has_diff=true" >> "$GITHUB_OUTPUT"
          else
@@ -9,7 +9,7 @@ jobs:
    runs-on: ubuntu-22.04
    steps:
    - name: Harden Runner
-      uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+      uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
      with:
        egress-policy: audit

@@ -27,25 +27,25 @@ jobs:

    steps:
    - name: Harden Runner
-      uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+      uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
      with:
        egress-policy: audit

    - name: Checkout repository
-      uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
      with:
        persist-credentials: false

    # Initializes the CodeQL tools for scanning.
    - name: Initialize CodeQL
-      uses: github/codeql-action/init@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
+      uses: github/codeql-action/init@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
      with:
        languages: c-cpp

    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
    # If this step fails, then you should remove it and run the build manually (see below)
    - name: Autobuild
-      uses: github/codeql-action/autobuild@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
+      uses: github/codeql-action/autobuild@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3

    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
+      uses: github/codeql-action/analyze@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
@@ -19,7 +19,7 @@ jobs:
      pull-requests: write
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -95,13 +95,13 @@ jobs:
              issue_number: issue_number,
              owner: context.repo.owner,
              repo: context.repo.repo,
-              body: '## 🔴 Amalgamation check failed! 🔴\nThe source code has not been amalgamated and/or formatted correctly, or `BUILD.bazel` is out of date.'
+              body: '## 🔴 Amalgamation check failed! 🔴\nThe source code has not been amalgamated and/or formatted correctly.'
                    + (hasPatch ? '\n\n📎 A ready-to-apply patch is attached to the [failed workflow run](' + runUrl + ') as the `amalgamation-patch` artifact.'
                                  + ' Download it, then apply it locally from the repository root with:'
                                  + '\n\n```shell\ngit apply amalgamation.patch\n```\n\n'
                                  + 'This does not require installing astyle yourself.'
                                : '')
                    + (first ? '\n\n@' + author + ' Please read and follow the [Contribution Guidelines]'
-                               + '(https://github.com/nlohmann/json/blob/develop/.github/CONTRIBUTING.md#amalgamate-the-source-code).'
+                               + '(https://github.com/nlohmann/json/blob/develop/.github/CONTRIBUTING.md#files-to-change).'
                             : '')
              })
@@ -17,12 +17,12 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

      - name: 'Checkout Repository'
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: 'Dependency Review'
@@ -27,12 +27,12 @@ jobs:
      security-events: write
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

      - name: Checkout code
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false

@@ -43,6 +43,6 @@ jobs:
          output: 'flawfinder_results.sarif'

      - name: Upload analysis results to GitHub Security tab
-        uses: github/codeql-action/upload-sarif@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
+        uses: github/codeql-action/upload-sarif@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
        with:
          sarif_file: ${{github.workspace}}/flawfinder_results.sarif
@@ -17,7 +17,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -26,7 +26,7 @@ jobs:
      DEVELOPER_DIR: /Applications/Xcode_${{ matrix.xcode }}.app/Contents/Developer

    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Run CMake
@@ -45,7 +45,7 @@ jobs:
      DEVELOPER_DIR: /Applications/Xcode_${{ matrix.xcode }}.app/Contents/Developer

    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Run CMake
@@ -62,7 +62,7 @@ jobs:
        standard: [11, 14, 17, 20, 23, 26]

    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Run CMake
@@ -7,6 +7,7 @@ on:
      - develop
    paths:
      - docs/mkdocs/**
+      - docs/examples/**
  workflow_dispatch:

 # we don't want to have concurrent jobs, and we don't want to cancel running jobs to avoid broken publications
@@ -26,11 +27,11 @@ jobs:
    runs-on: ubuntu-22.04
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0

      - name: Install virtual environment
        run: make install_venv -C docs/mkdocs
@@ -36,17 +36,17 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

      - name: "Checkout code"
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false

      - name: "Run analysis"
-        uses: ossf/scorecard-action@2d1146689b8cda280b9bc96326124645441f03bc # v2.4.4
+        uses: ossf/scorecard-action@4eaacf0543bb3f2c246792bd56e8cdeffafb205a # v2.4.3
        with:
          results_file: results.sarif
          results_format: sarif
@@ -76,6 +76,6 @@ jobs:

      # Upload the results to GitHub's code scanning dashboard.
      - name: "Upload to code-scanning"
-        uses: github/codeql-action/upload-sarif@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
+        uses: github/codeql-action/upload-sarif@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
        with:
          sarif_file: results.sarif
@@ -32,12 +32,12 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

      # Checkout project source
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false

@@ -61,7 +61,7 @@ jobs:

      # Upload SARIF file generated in previous step
      - name: Upload SARIF file
-        uses: github/codeql-action/upload-sarif@b96794f015dfd88f77b49b1c93e0fa7110f94c63 # v4.38.0
+        uses: github/codeql-action/upload-sarif@54f647b7e1bb85c95cddabcd46b0c578ec92bc1a # v4.36.3
        with:
          sarif_file: semgrep.sarif
        if: always()
@@ -16,11 +16,11 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

-      - uses: actions/stale@4391f3da665fdf50b6810c1a66712fb9ba21aa93 # v11.0.0
+      - uses: actions/stale@eb5cf3af3ac0a1aa4c9c45633dd1ae542a27a899 # v10.3.0
        with:
          stale-issue-label: 'state: stale'
          stale-pr-label: 'state: stale'
@@ -21,11 +21,11 @@ jobs:
    runs-on: ubuntu-latest
    container: gcc:latest
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -35,7 +35,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -43,11 +43,11 @@ jobs:
        run: |
          wget -q -O - "https://github.com/facebook/infer/releases/download/v1.3.0/infer-linux-x86_64-v1.3.0.tar.xz" | sudo tar -C /opt -xJ
          sudo ln -s /opt/infer-linux-x86_64-v1.3.0/bin/infer /usr/local/bin/infer
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -60,17 +60,17 @@ jobs:
        target: [ci_test_amalgamation, ci_test_single_header, ci_cppcheck, ci_cpplint, ci_reproducible_tests, ci_non_git_tests, ci_offline_testdata, ci_reuse_compliance, ci_test_valgrind]
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

      - name: Install Valgrind
        run: sudo apt-get update ; sudo apt-get install -y valgrind
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -85,11 +85,11 @@ jobs:
    steps:
      - name: Install git, clang-tools, iwyu (ci_single_binaries), and unzip
        run: apt-get update ; apt-get install -y git clang-tools iwyu unzip
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -100,15 +100,15 @@ jobs:
    container: ubuntu:focal
    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_skiplibraryversioncheck, ci_test_simdutf, ci_test_strict_nul_handling, 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]
    steps:
      - name: Install build-essential
        run: apt-get update ; apt-get install -y build-essential unzip wget git libssl-dev
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -118,11 +118,11 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Install dependencies and de_DE locale
@@ -142,7 +142,7 @@ jobs:
          name: code-coverage-report
          path: ${{ github.workspace }}/build/html
      - name: Publish report to Coveralls
-        uses: coverallsapp/github-action@8d6379e14d29928660c4ba802d8e85393440b329 # v2.3.8
+        uses: coverallsapp/github-action@5cbfd81b66ca5d10c19b062c04de0199c215fb6e # v2.3.7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          path-to-lcov: ${{ github.workspace }}/build/json.info.filtered.noexcept
@@ -163,15 +163,7 @@ jobs:
          export DEBIAN_FRONTEND=noninteractive
          apt-get update
          apt-get install -y --no-install-recommends software-properties-common ca-certificates gnupg make git
-          # add-apt-repository resolves the PPA through the Launchpad API,
-          # which intermittently times out or fails the team lookup (the plain
-          # "deb ..." sources below never hit Launchpad and never flake).
-          # Retry with backoff so a transient Launchpad blip does not fail CI.
-          for attempt in 1 2 3 4 5; do
-            add-apt-repository -y ppa:ubuntu-toolchain-r/test && break
-            echo "::warning::add-apt-repository ppa:ubuntu-toolchain-r/test failed (attempt ${attempt}/5); retrying"
-            sleep $((attempt * 10))
-          done
+          add-apt-repository -y ppa:ubuntu-toolchain-r/test
          apt-add-repository -y "deb http://archive.ubuntu.com/ubuntu/ bionic main"
          apt-add-repository -y "deb http://archive.ubuntu.com/ubuntu/ bionic universe"
          apt-add-repository -y "deb http://archive.ubuntu.com/ubuntu/ xenial main"
@@ -180,11 +172,11 @@ jobs:
          apt-add-repository -y "deb http://archive.ubuntu.com/ubuntu/ xenial-updates universe"
          apt-get update
          apt-get install -y --no-install-recommends g++-${{ matrix.compiler }}
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: CXX=g++-${{ matrix.compiler }} cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -198,11 +190,11 @@ jobs:
        compiler: ['7', '8', '9', '10', '11', '12', '13', '14', '15', 'latest']
    container: gcc:${{ matrix.compiler }}
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -212,14 +204,14 @@ jobs:
    runs-on: ubuntu-latest
    strategy:
      matrix:
-        compiler: ['3.4', '3.5', '3.6', '3.7', '3.8', '3.9', '4', '5', '6', '7', '8', '9', '10', '11', '12', '13', '14', '15-bullseye', '16', '17', '18', '19', '20', '21', '22', 'latest']
+        compiler: ['3.4', '3.5', '3.6', '3.7', '3.8', '3.9', '4', '5', '6', '7', '8', '9', '10', '11', '12', '13', '14', '15-bullseye', '16', '17', '18', '19', '20', 'latest']
    container: silkeh/clang:${{ matrix.compiler }}
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Set env FORCE_STDCPPFS_FLAG for clang 7 / 8 / 9 / 10
        run: echo "JSON_FORCED_GLOBAL_COMPILE_OPTIONS=-DJSON_HAS_FILESYSTEM=0;-DJSON_HAS_EXPERIMENTAL_FILESYSTEM=0" >> "$GITHUB_ENV"
        if: ${{ matrix.compiler == '7' || matrix.compiler == '8' || matrix.compiler == '9' || matrix.compiler == '10' }}
@@ -235,11 +227,11 @@ jobs:
      matrix:
        standard: [11, 14, 17, 20, 23, 26]
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -255,11 +247,11 @@ jobs:
    steps:
      - name: Install git and unzip
        run: apt-get update ; apt-get install -y git unzip
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build with libc++
@@ -282,11 +274,11 @@ jobs:
        cuda: ['11.8.0', '12.1.1', '12.6.3']
    container: nvidia/cuda:${{ matrix.cuda }}-devel-ubuntu22.04
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -299,14 +291,14 @@ jobs:
    runs-on: ubuntu-latest
    container: ${{ matrix.container }}
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      # The module test uses `import std;`, which needs CMake's experimental
      # import-std support. Its opt-in token is CMake-version-specific, so pin
      # CMake to the version whose token is set in tests/module_cpp20/CMakeLists.txt.
      - name: Get pinned CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
        with:
          cmakeVersion: 4.3.4
      # Clang: the std library module is provided by libc++ (the image's libstdc++
@@ -328,11 +320,11 @@ jobs:
    # Intel's own last officially published image that still includes it.
    container: intel/oneapi-hpckit:2023.2.1-devel-ubuntu22.04
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -345,9 +337,9 @@ jobs:
    runs-on: ubuntu-latest
    container: intel/oneapi-hpckit:latest
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -357,9 +349,9 @@ jobs:
    runs-on: ubuntu-latest
    container: nvcr.io/nvidia/nvhpc:25.5-devel-cuda12.9-ubuntu22.04
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -369,17 +361,17 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

      - name: Install emscripten
        uses: mymindstorm/setup-emsdk@4528d102f7230f0e7b276855c01ea1159be0e984 # v16
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Run CMake
        run: cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=$EMSDK/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake -GNinja
      - name: Build
@@ -392,11 +384,11 @@ jobs:
        target: [ci_test_examples, ci_test_build_documentation]
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Run CMake
@@ -24,7 +24,7 @@ jobs:
        architecture: [x64, x86]

    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Set up MinGW
@@ -49,7 +49,7 @@ jobs:
    runs-on: windows-2022

    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Set extra CXX_FLAGS for latest std_version
@@ -86,9 +86,9 @@ jobs:
    runs-on: windows-2025

    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
      - name: Set extra CXX_FLAGS for latest std_version
        # /wd5285 silences C5285 emitted by the bundled third-party doctest.h, which
        # specializes std::tuple (newly diagnosed by the VS2026 v145 toolset)
@@ -122,13 +122,13 @@ jobs:
    runs-on: windows-11-arm

    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
      - name: Run CMake (Release)
-        run: cmake -S . -B build -G "Visual Studio 18 2026" -A ARM64 -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="/W4 /WX"
+        run: cmake -S . -B build -G "Visual Studio 17 2022" -A ARM64 -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="/W4 /WX"
        if: matrix.build_type == 'Release'
        shell: pwsh
      - name: Run CMake (Debug)
-        run: cmake -S . -B build -G "Visual Studio 18 2026" -A ARM64 -DJSON_BuildTests=On -DJSON_FastTests=ON -DCMAKE_CXX_FLAGS="/W4 /WX"
+        run: cmake -S . -B build -G "Visual Studio 17 2022" -A ARM64 -DJSON_BuildTests=On -DJSON_FastTests=ON -DCMAKE_CXX_FLAGS="/W4 /WX"
        if: matrix.build_type == 'Debug'
        shell: pwsh
      - name: Build
@@ -143,7 +143,7 @@ jobs:
        version: [11.0.1, 12.0.1, 13.0.1, 14.0.6, 15.0.7, 16.0.6, 18.1.8, 19.1.7, 20.1.8]

    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Install Clang
@@ -153,20 +153,10 @@ jobs:
        with:
          platform: x64
          version: 12.2.0 # https://github.com/egor-tensin/setup-mingw/issues/14
-      # CMAKE_CXX_FLAGS_DEBUG is overridden to drop the default -g: linking
-      # test-regression2_cpp20 intermittently fails with "relocation truncated
-      # to fit: IMAGE_REL_AMD64_SECREL against `.debug_line'" because the
-      # MinGW linker cannot relocate the debug sections this test produces.
-      # The tests are only built and run here, so the debug info is not used.
-      # Do not add -O1 here to shrink the objects further: it does make them
-      # link, but the binaries clang 11.0.1 and clang 18.1.8 then produce crash
-      # before doctest prints its first line - 39 of 102 tests on clang 18.
-      # Keep the objects small by splitting the test files instead.
      - name: Run CMake
        run: cmake -S . -B build ^
             -DCMAKE_CXX_COMPILER="C:/Program Files/LLVM/bin/clang++.exe" ^
             -DCMAKE_CXX_FLAGS="--target=x86_64-w64-mingw32 -stdlib=libstdc++ -pthread" ^
-             -DCMAKE_CXX_FLAGS_DEBUG="-g0" ^
             -DCMAKE_EXE_LINKER_FLAGS="-lwinpthread" ^
             -G"MinGW Makefiles" ^
             -DCMAKE_BUILD_TYPE=Debug ^
@@ -183,7 +173,7 @@ jobs:
        architecture: [Win32, x64]

    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      - name: Run CMake
@@ -196,14 +186,14 @@ jobs:
  ci_module_cpp20:
    runs-on: windows-2022
    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
      # The module test uses `import std;`, which needs CMake's experimental
      # import-std support. Its opt-in token is CMake-version-specific, so pin
      # CMake to the version whose token is set in tests/module_cpp20/CMakeLists.txt.
      - name: Get pinned CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
        with:
          cmakeVersion: 4.3.4
      - name: Run CMake (Debug)
@@ -30,10 +30,8 @@ cc_library(
        "include/nlohmann/detail/input/input_adapters.hpp",
        "include/nlohmann/detail/input/json_sax.hpp",
        "include/nlohmann/detail/input/lexer.hpp",
-        "include/nlohmann/detail/input/number_parse.hpp",
        "include/nlohmann/detail/input/parser.hpp",
        "include/nlohmann/detail/input/position_t.hpp",
-        "include/nlohmann/detail/input/string_scan.hpp",
        "include/nlohmann/detail/iterators/internal_iterator.hpp",
        "include/nlohmann/detail/iterators/iter_impl.hpp",
        "include/nlohmann/detail/iterators/iteration_proxy.hpp",
@@ -51,14 +49,12 @@ cc_library(
        "include/nlohmann/detail/meta/detected.hpp",
        "include/nlohmann/detail/meta/identity_tag.hpp",
        "include/nlohmann/detail/meta/is_sax.hpp",
-        "include/nlohmann/detail/meta/logic.hpp",
        "include/nlohmann/detail/meta/std_fs.hpp",
        "include/nlohmann/detail/meta/type_traits.hpp",
        "include/nlohmann/detail/meta/void_t.hpp",
        "include/nlohmann/detail/output/binary_writer.hpp",
        "include/nlohmann/detail/output/output_adapters.hpp",
        "include/nlohmann/detail/output/serializer.hpp",
-        "include/nlohmann/detail/recursion_depth_limit.hpp",
        "include/nlohmann/detail/string_concat.hpp",
        "include/nlohmann/detail/string_escape.hpp",
        "include/nlohmann/detail/string_utils.hpp",
@@ -59,7 +59,6 @@ option(JSON_LegacyDiscardedValueComparison "Enable legacy discarded value compar
 option(JSON_Install                        "Install CMake targets during install step." ${MAIN_PROJECT})
 option(JSON_MultipleHeaders                "Use non-amalgamated version of the library." ON)
 option(JSON_SystemInclude                  "Include as system headers (skip for clang-tidy)." OFF)
-option(JSON_StrictNulHandling              "Build with strict NUL-byte handling enabled." OFF)

 if (JSON_CI)
    include(ci)
@@ -109,10 +108,6 @@ if (JSON_Diagnostics)
    message(STATUS "Diagnostics enabled (JSON_DIAGNOSTICS=1)")
 endif()

-if (JSON_StrictNulHandling)
-    message(STATUS "Strict NUL-byte handling enabled (JSON_STRICT_NUL_HANDLING=1)")
-endif()
-
 if (JSON_Diagnostic_Positions)
    message(STATUS "Diagnostic positions enabled (JSON_DIAGNOSTIC_POSITIONS=1)")
 endif()
@@ -146,7 +141,6 @@ target_compile_definitions(
    $<$<BOOL:${JSON_Diagnostics}>:JSON_DIAGNOSTICS=1>
    $<$<BOOL:${JSON_Diagnostic_Positions}>:JSON_DIAGNOSTIC_POSITIONS=1>
    $<$<BOOL:${JSON_LegacyDiscardedValueComparison}>:JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1>
-    $<$<BOOL:${JSON_StrictNulHandling}>:JSON_STRICT_NUL_HANDLING=1>
 )

 target_include_directories(
@@ -250,16 +250,12 @@ Further documentation:

 ### `BUILD.bazel`

-The build definition for [Bazel](https://bazel.build). The file is generated by
-`cmake/scripts/gen_bazel_build_file.cmake`, which derives the header list from the files in `include`; change the
-script rather than editing the file by hand. The file can be updated by calling
+The file can be updated by calling

 ```shell
 make BUILD.bazel
 ```

-The "Check amalgamation" workflow fails if the file is out of date.
-
 ### `meson.build`

 The build definition for the [Meson](https://mesonbuild.com) build system.
@@ -1,4 +1,4 @@
-.PHONY: pretty clean ChangeLog.md release update_hedley update_hedley_undef BUILD.bazel
+.PHONY: pretty clean ChangeLog.md release

 ##########################################################################
 # configuration
@@ -30,9 +30,8 @@ AMALGAMATED_FWD_FILE=single_include/nlohmann/json_fwd.hpp
 # main target
 all:
 	@echo "amalgamate - amalgamate files single_include/nlohmann/json{,_fwd}.hpp from the include/nlohmann sources"
-	@echo "BUILD.bazel - regenerate the Bazel BUILD file from the include/nlohmann sources"
 	@echo "ChangeLog.md - generate ChangeLog file"
-	@echo "check-amalgamation - check whether sources have been amalgamated and BUILD.bazel is up to date"
+	@echo "check-amalgamation - check whether sources have been amalgamated"
 	@echo "clean - remove built files"
 	@echo "doctest - compile example files and check their output"
 	@echo "fuzz_testing - prepare fuzz testing of the JSON parser"
@@ -42,8 +41,6 @@ all:
 	@echo "fuzz_testing_ubjson - prepare fuzz testing of the UBJSON parser"
 	@echo "pretty - beautify code with Artistic Style"
 	@echo "run_benchmarks - build and run benchmarks"
-	@echo "update_hedley - download Hedley and regenerate hedley.hpp / hedley_undef.hpp"
-	@echo "update_hedley_undef - rebuild hedley_undef.hpp from the JSON_HEDLEY_* #define names in hedley.hpp"


 ##########################################################################
@@ -173,13 +170,8 @@ check-amalgamation:
 	@diff $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_FWD_FILE)~ || (echo "===================================================================\n  Amalgamation required! Please read the contribution guidelines\n  in file .github/CONTRIBUTING.md.\n===================================================================" ; mv $(AMALGAMATED_FWD_FILE)~ $(AMALGAMATED_FWD_FILE) ; false)
 	@mv $(AMALGAMATED_FILE)~ $(AMALGAMATED_FILE)
 	@mv $(AMALGAMATED_FWD_FILE)~ $(AMALGAMATED_FWD_FILE)
-	@mv BUILD.bazel BUILD.bazel~
-	@$(MAKE) BUILD.bazel
-	@diff BUILD.bazel BUILD.bazel~ || (echo "===================================================================\n  BUILD.bazel is out of date! Please run 'make BUILD.bazel'.\n===================================================================" ; mv BUILD.bazel~ BUILD.bazel ; false)
-	@mv BUILD.bazel~ BUILD.bazel

-# generate the Bazel BUILD file; phony, because a removed header would not trigger a rebuild
-BUILD.bazel:
+BUILD.bazel: $(SRCS)
 	cmake -P cmake/scripts/gen_bazel_build_file.cmake

 ##########################################################################
@@ -249,24 +241,11 @@ update_hedley:
 	rm -f include/nlohmann/thirdparty/hedley/hedley.hpp include/nlohmann/thirdparty/hedley/hedley_undef.hpp
 	curl https://raw.githubusercontent.com/nemequ/hedley/master/hedley.h -o include/nlohmann/thirdparty/hedley/hedley.hpp
 	$(SED) -i 's/HEDLEY_/JSON_HEDLEY_/g' include/nlohmann/thirdparty/hedley/hedley.hpp
+	grep "[[:blank:]]*#[[:blank:]]*undef" include/nlohmann/thirdparty/hedley/hedley.hpp | grep -v "__" | sort | uniq | $(SED) 's/ //g' | $(SED) 's/undef/undef /g' > include/nlohmann/thirdparty/hedley/hedley_undef.hpp
 	$(SED) -i '1s/^/#pragma once\n\n/' include/nlohmann/thirdparty/hedley/hedley.hpp
-	$(MAKE) update_hedley_undef
+	$(SED) -i '1s/^/#pragma once\n\n/' include/nlohmann/thirdparty/hedley/hedley_undef.hpp
 	$(MAKE) amalgamate

-# Rebuild hedley_undef.hpp from every JSON_HEDLEY_* name that hedley.hpp
-# #defines. Hedley does not #undef all of its public macros internally (see
-# #5408), so grepping those #undef lines misses names such as
-# JSON_HEDLEY_PRAGMA. cmake/scripts/gen_hedley_undef_check.cmake is the
-# single source of truth for this extraction (tests/CMakeLists.txt uses the
-# same script, in MODE=checks, to generate the matching leak-check test), so
-# the vendored header, the generated #undef list, and the regression test
-# cannot drift apart.
-update_hedley_undef:
-	cmake -DHEDLEY_HPP=include/nlohmann/thirdparty/hedley/hedley.hpp \
-	      -DOUTPUT=include/nlohmann/thirdparty/hedley/hedley_undef.hpp \
-	      -DMODE=undef \
-	      -P cmake/scripts/gen_hedley_undef_check.cmake
-
 ##########################################################################
 # serve_header.py
 ##########################################################################
@@ -42,7 +42,6 @@
  - [Specializing enum conversion](#specializing-enum-conversion)
  - [Binary formats (BSON, CBOR, MessagePack, UBJSON, and BJData)](#binary-formats-bson-cbor-messagepack-ubjson-and-bjdata)
 - [Customers](#customers)
- [Ecosystem](#ecosystem)
 - [Supported compilers](#supported-compilers)
 - [Integration](#integration)
  - [CMake](#cmake)
@@ -91,6 +90,7 @@ You can sponsor this library at [GitHub Sponsors](https://github.com/sponsors/nl
 - [Steve Sperandeo](https://github.com/homer6)
 - [Robert Jefe Lindstädt](https://github.com/eljefedelrodeodeljefe)
 - [Steve Wagner](https://github.com/ciroque)
+- [Lion Yang](https://github.com/LionNatsu)

 ### Further support

@@ -1187,11 +1187,6 @@ The library is used in multiple projects, applications, operating systems, etc.

 [![logos of customers using the library](docs/mkdocs/docs/images/customers.png)](https://json.nlohmann.me/home/customers/)

-## Ecosystem
-
-Beyond projects that use the library, there are third-party projects that build on top of it - schema validators,
-language bindings, format converters, and the like. See the curated [Ecosystem](https://json.nlohmann.me/community/ecosystem/) page.
-
 ## Supported compilers

 Though it's 2026 already, the support for C++11 is still a bit sparse. Currently, the following compilers are known to work:
@@ -1421,7 +1416,7 @@ I deeply appreciate the help of the following people.
 6. [Joshua C. Randall](https://github.com/jrandall) fixed a bug in the floating-point serialization.
 7. [Aaron Burghardt](https://github.com/aburgh) implemented code to parse streams incrementally. Furthermore, he greatly improved the parser class by allowing the definition of a filter function to discard undesired elements while parsing.
 8. [Daniel Kopeček](https://github.com/dkopecek) fixed a bug in the compilation with GCC 5.0.
-9. [Fiona Johanna Weber](https://github.com/Fiona-J-W) fixed a bug in and improved the performance of the comparison operators.
+9. [Florian Weber](https://github.com/Florianjw) fixed a bug in and improved the performance of the comparison operators.
 10. [Eric Cornelius](https://github.com/EricMCornelius) pointed out a bug in the handling with NaN and infinity values. He also improved the performance of the string escaping.
 11. [易思龙](https://github.com/likebeta) implemented a conversion from anonymous enums.
 12. [kepkin](https://github.com/kepkin) patiently pushed forward the support for Microsoft Visual Studio.
@@ -1523,14 +1518,14 @@ I deeply appreciate the help of the following people.
 108. [Kevin Tonon](https://github.com/ktonon) overworked the C++11 compiler checks in CMake.
 109. [Axel Huebl](https://github.com/ax3l) simplified a CMake check and added support for the [Spack package manager](https://spack.io).
 110. [Carlos O'Ryan](https://github.com/coryan) fixed a typo.
-111. [James Upjohn](https://github.com/jupjohn) fixed a version number in the compilers section.
+111. [James Upjohn](https://github.com/jammehcow) fixed a version number in the compilers section.
 112. [Chuck Atkins](https://github.com/chuckatkins) adjusted the CMake files to the CMake packaging guidelines and provided documentation for the CMake integration.
 113. [Jan Schöppach](https://github.com/dns13) fixed a typo.
 114. [martin-mfg](https://github.com/martin-mfg) fixed a typo.
 115. [Matthias Möller](https://github.com/TinyTinni) removed the dependency from `std::stringstream`.
 116. [agrianius](https://github.com/agrianius) added code to use alternative string implementations.
 117. [Daniel599](https://github.com/Daniel599) allowed to use more algorithms with the `items()` function.
-118. [Julius Rakow](https://github.com/juliusrakow) fixed the Meson include directory and fixed the links to [cppreference.com](https://cppreference.com).
+118. [Julius Rakow](https://github.com/jrakow) fixed the Meson include directory and fixed the links to [cppreference.com](https://cppreference.com).
 119. [Sonu Lohani](https://github.com/sonulohani) fixed the compilation with MSVC 2015 in debug mode.
 120. [grembo](https://github.com/grembo) fixed the test suite and re-enabled several test cases.
 121. [Hyeon Kim](https://github.com/simnalamburt) introduced the macro `JSON_INTERNAL_CATCH` to control the exception handling inside the library.
@@ -1581,7 +1576,7 @@ I deeply appreciate the help of the following people.
 166. [Mark Beckwith](https://github.com/wythe) fixed a typo.
 167. [yann-morin-1998](https://github.com/yann-morin-1998) helped to reduce the CMake requirement to version 3.1.
 168. [Konstantin Podsvirov](https://github.com/podsvirov) maintains a package for the MSYS2 software distro.
-169. [remyabel](https://github.com/remyabel2) added GNUInstallDirs to the CMake files.
+169. [remyabel](https://github.com/remyabel) added GNUInstallDirs to the CMake files.
 170. [Taylor Howard](https://github.com/taylorhoward92) fixed a unit test.
 171. [Gabe Ron](https://github.com/Macr0Nerd) implemented the `to_string` method.
 172. [Watal M. Iwasaki](https://github.com/heavywatal) fixed a Clang warning.
@@ -1608,7 +1603,7 @@ I deeply appreciate the help of the following people.
 193. [Hubert Chathi](https://github.com/uhoreg) made CMake's version config file architecture-independent.
 194. [OmnipotentEntity](https://github.com/OmnipotentEntity) implemented the binary values for CBOR, MessagePack, BSON, and UBJSON.
 195. [ArtemSarmini](https://github.com/ArtemSarmini) fixed a compilation issue with GCC 10 and fixed a leak.
-196. [Evgenii Sopov](https://github.com/sea5kg) integrated the library to the wsjcpp package manager.
+196. [Evgenii Sopov](https://github.com/sea-kg) integrated the library to the wsjcpp package manager.
 197. [Sergey Linev](https://github.com/linev) fixed a compiler warning.
 198. [Miguel Magalhães](https://github.com/magamig) fixed the year in the copyright.
 199. [Gareth Sylvester-Bradley](https://github.com/garethsb-sony) fixed a compilation issue with MSVC.
@@ -1702,7 +1697,7 @@ I deeply appreciate the help of the following people.
 287. [NN](https://github.com/NN---) added the Visual Studio output directory to `.gitignore`.
 288. [Romain Reignier](https://github.com/romainreignier) improved the performance of the vector output adapter.
 289. [Mike](https://github.com/Mike-Leo-Smith) fixed the `std::iterator_traits`.
-290. [Richard Hozák](https://github.com/richardhozak) added macro `JSON_NO_ENUM` to disable default enum conversions.
+290. [Richard Hozák](https://github.com/zxey) added macro `JSON_NO_ENUM` to disable default enum conversions.
 291. [vakokako](https://github.com/vakokako) fixed tests when compiling with C++20.
 292. [Alexander “weej” Jones](https://github.com/alexweej) fixed an example in the README.
 293. [Eli Schwartz](https://github.com/eli-schwartz) added more files to the `include.zip` archive.
@@ -1727,7 +1722,7 @@ I deeply appreciate the help of the following people.
 312. [Gareth Sylvester-Bradley](https://github.com/garethsb) added `operator/=` and `operator/` to construct JSON pointers.
 313. [Michael Macnair](https://github.com/mykter) added support for afl-fuzz testing.
 314. [Berkus Decker](https://github.com/berkus) fixed a typo in the README.
-315. [Illia Polishchuk](https://github.com/ilqvya) improved the CMake testing.
+315. [Illia Polishchuk](https://github.com/effolkronium) improved the CMake testing.
 316. [Ikko Ashimine](https://github.com/eltociear) fixed a typo.
 317. [Raphael Grimm](https://github.com/barcode) added the possibility to define a custom base class.
 318. [tocic](https://github.com/tocic) fixed typos in the documentation.
@@ -1797,66 +1792,6 @@ I deeply appreciate the help of the following people.
 382. [bitFiedler](https://github.com/bitFiedler) made GDB pretty printer work with Python 3.8.
 383. [Gianfranco Costamagna](https://github.com/LocutusOfBorg) fixed a compiler warning.
 384. [risa2000](https://github.com/risa2000) made `std::filesystem::path` conversion to/from UTF-8 encoded string explicit.
-385. [AM](https://github.com/maqnouch) fixed typos in the README.
-386. [dmenendez-gruposantander](https://github.com/dmenendez-gruposantander) fixed typos in the comments of the examples.
-387. [Mihai Stan](https://github.com/mstan-xx) fixed comparisons against the literal `0`.
-388. [Matt Gumbel](https://github.com/intelmatt) fixed some `-Weffc++` warnings.
-389. [vimpunk](https://github.com/vimpunk) moved a lambda out of an unevaluated context to support older compilers.
-390. [Chris Harris](https://github.com/cjh1) fixed the compilation with GCC 4.8.
-391. [Palmer Dabbelt](https://github.com/palmer-dabbelt) generated and installed a pkg-config file.
-392. [Gus Pozuelo](https://github.com/ap-viavi) made `ordered_map` compatible with GCC 5.5, Clang 3.6, and Xcode 9.
-393. [AK](https://github.com/Lioncky) fixed an MSVC build error caused by the `min`/`max` macros from `windows.h`.
-394. [Sergiu Deitsch](https://github.com/sergiud) provided a fallback for missing `char8_t` support.
-395. [Xiaochuan Ye](https://github.com/XueSongTap) fixed `from_msgpack` for `std::byte` input by specializing `std::char_traits`.
-396. [Ville Vesilehto](https://github.com/thevilledev) fixed an overflow in the BJData size calculation and rejected overflowing negative integers in CBOR.
-397. [NmPassTHFan](https://github.com/nmpassthf) replaced the deprecated `std::is_trivial` for C++26.
-398. [Chris Ever](https://github.com/chirsz-ever) added the `ignore_trailing_commas` parser option.
-399. [Kuan-Fu Wu](https://github.com/kfwu1999) fixed the example code for `json_pointer` initialization.
-400. [David Kilzer](https://github.com/ddkilzer) added a missing header to the input adapters.
-401. [Miko](https://github.com/mikomikotaishi) added proper C++20 module support, simplified the module API, and fixed missing exports.
-402. [hitgirl](https://github.com/hitgil) fixed the CMake configuration when cross-compiling.
-403. [Devon Thomas](https://github.com/ThomaDevOSU) mentioned the Artistic Style formatting in the contribution guidelines.
-404. [Erik Hu](https://github.com/Erikhu1) made Coveralls upload errors non-fatal in the CI.
-405. [co63oc](https://github.com/co63oc) fixed typos.
-406. [DmitriBogdanov](https://github.com/DmitriBogdanov) fixed broken package manager links in the documentation.
-407. [Bander](https://github.com/banderzhm) improved the MSVC compatibility of the C++ modules.
-408. [Andy Choi](https://github.com/ccpong) removed an unnecessary `template` keyword before `get` in the README and the documentation.
-409. [SamareshSingh](https://github.com/ssam18) fixed single-element brace initialization to copy/move instead of wrapping in an array, fixed the `WITH_DEFAULT` macros for `ordered_map`, and handled moved events in `serve_header.py`.
-410. [Aditya](https://github.com/Lumowhisp) improved the documentation of the documentation generation.
-411. [cheese1](https://github.com/cheese1) clarified the README.
-412. [KhloodElhossiny](https://github.com/khloodelhossiny) enabled `std::string_view` keys in `operator[]`.
-413. [Charles Cabergs](https://github.com/cacharle) fixed a `-Wtautological-constant-out-of-range-compare` warning.
-414. [EALePain](https://github.com/EALePain) made the `std::tuple` conversion work with reference types such as `std::tie`.
-415. [koala_oishi](https://github.com/chibi-dogs) fixed grammatical wording in the README.
-416. [riccardoori11](https://github.com/riccardoori11) fixed a typo in the documentation.
-417. [Swastik Bose](https://github.com/VasuBhakt) fixed the parent pointers after `update()` with `JSON_DIAGNOSTICS` and fixed the Doxygen autolinking of requirements.
-418. [trdesilva](https://github.com/trdesilva) added `front`, `pop_front`, and `push_front` to `json_pointer`.
-419. [Akhilesh Arora](https://github.com/akhilesharora) fixed an incomplete-type error with `ordered_json`.
-420. [Hariom Phulre](https://github.com/hariomphulre) fixed the C++20 modules compilation with GCC.
-421. [Kirill Lokotkov](https://github.com/RUSLoker) fixed printing `long double` values.
-422. [George Sedov](https://github.com/radistmorse) added the `NLOHMANN_DEFINE_TYPE_*_WITH_NAMES` macros.
-423. [Caillin Nugent](https://github.com/nugentcaillin) added the `NLOHMANN_JSON_SERIALIZE_ENUM_STRICT` macro.
-424. [Cosmin D.](https://github.com/drcosmin) fixed `std::filesystem::path` conversions and added an MSVC workaround for `std::unique_ptr`.
-425. [Paul Dreik](https://github.com/pauldreik) fixed a test relying on implementation-specific behavior.
-426. [Daniel Falk](https://github.com/daniel-falk) added missing copyright notices to the SBOM.
-427. [Federico Sfriso](https://github.com/federicosfriso05-dotcom) added support for constructing JSON values from C++20 range views.
-428. [Luke Banicevic](https://github.com/banaboi) fixed corrupt BSON output for lengths exceeding `INT32_MAX`, cleaned up the BSON writer, and improved the documentation.
-429. [Patrick Armstrong](https://github.com/Patrick10199) updated the CBOR references and the half-precision float assertions.
-430. [Yash Bavadiya](https://github.com/xevrion) added checks to all BSON reads.
-431. [hum4nBeing](https://github.com/hum4nBeing) fixed the overflow handling of high-precision numbers in UBJSON.
-432. [tomatotomata](https://github.com/tomatotomata) added checks for reading CBOR tagged subtypes.
-433. [YingqiDuan](https://github.com/YingqiDuan) documented the BSON interoperability.
-434. [KBS](https://github.com/youdie006) documented the standards compliance and the strictness of `parse()` and `operator>>`.
-435. [Petr Bělohlávek](https://github.com/petrbel) added Clang 21 and 22 to the CI.
-436. [Dmitry Rantovov](https://github.com/darkdi) fixed the placement of a CBOR documentation block.
-437. [ljcjclljc](https://github.com/ljcjclljc) fixed the comparison of large unsigned integers with signed integers.
-438. [Sahil Kamate](https://github.com/sahilkamate03) fixed the handling of CBOR tags 0-5 and 21-23.
-439. [Krishnanand G](https://github.com/Krishnanand-G) made the UBJSON writer reject `use_type` without `use_size`.
-440. [whn](https://github.com/Whning0513) documented the lenient BSON input handling and corrected the complexity of `to_bson`.
-441. [elix3r](https://github.com/22elix3r) fixed `update()` with `merge_objects` when merging a primitive into an object.
-442. [Avionic Harshit](https://github.com/avionicharshit-byte) made `diff()` linear when an array shrinks.
-443. [Qatadaha Bin Matloob](https://github.com/qatcod) fixed comparisons between integers and floats and fixed unparsable BJData output.
-444. [Wu Shuwen](https://github.com/dajiaohuang) removed an unused include.

 Thanks a lot for helping out! Please [let me know](mailto:mail@nlohmann.me) if I forgot someone.

@@ -1867,13 +1802,13 @@ The library itself consists of a single header file licensed under the MIT licen
 - [**amalgamate.py - Amalgamate C source and header files**](https://github.com/edlund/amalgamate) to create a single header file
 - [**American fuzzy lop**](https://lcamtuf.coredump.cx/afl/) for fuzz testing
 - [**AppVeyor**](https://www.appveyor.com) for [continuous integration](https://ci.appveyor.com/project/nlohmann/json) on Windows
- [**Artistic Style**](https://astyle.sourceforge.net) for automatic source code indentation
+- [**Artistic Style**](http://astyle.sourceforge.net) for automatic source code indentation
 - [**Clang**](https://clang.llvm.org) for compilation with code sanitizers
 - [**CMake**](https://cmake.org) for build automation
 - [**Codacy**](https://www.codacy.com) for further [code analysis](https://app.codacy.com/gh/nlohmann/json/dashboard)
 - [**Coveralls**](https://coveralls.io) to measure [code coverage](https://coveralls.io/github/nlohmann/json)
 - [**Coverity Scan**](https://scan.coverity.com) for [static analysis](https://scan.coverity.com/projects/nlohmann-json)
- [**cppcheck**](https://cppcheck.sourceforge.io) for static analysis
+- [**cppcheck**](http://cppcheck.sourceforge.net) for static analysis
 - [**doctest**](https://github.com/onqtam/doctest) for the unit tests
 - [**GitHub Changelog Generator**](https://github.com/skywinder/github-changelog-generator) to generate the [ChangeLog](https://github.com/nlohmann/json/blob/develop/ChangeLog.md)
 - [**Google Benchmark**](https://github.com/google/benchmark) to implement the benchmarks
@@ -1888,15 +1823,6 @@ The library itself consists of a single header file licensed under the MIT licen

 ## Notes

-### Standards compliance
-
-The library targets strict conformance with [RFC 8259](https://tools.ietf.org/html/rfc8259.html). Both the original [JSONTestSuite](https://github.com/nst/JSONTestSuite) and its updated revision are exercised in CI; their test data is downloaded from [`nlohmann/json_test_data`](https://github.com/nlohmann/json_test_data) at configure time rather than committed to this repository (see [`tests/src/unit-testsuites.cpp`](https://github.com/nlohmann/json/blob/develop/tests/src/unit-testsuites.cpp)):
-
- The updated revision runs all mandatory `y_` (must-accept) and `n_` (must-reject) cases through the strict [`parse()`](https://json.nlohmann.me/api/basic_json/parse/) entry point; the original suite runs its `n_` cases through `parse()` and its `y_` cases through [`operator>>`](https://json.nlohmann.me/api/operator_gtgt/).
- The `i_` (implementation-defined) cases are, by RFC 8259, free to be accepted *or* rejected, so "passing all `i_` cases" is not a meaningful conformance metric. The library makes deliberate, documented choices there: nesting depth is not artificially limited, a leading UTF-8 byte order mark is silently ignored, [Unicode noncharacters](https://www.unicode.org/faq/private_use.html#nonchar1) are forwarded unchanged, invalid UTF-8 and lone/unpaired UTF-16 surrogates are rejected (stricter than required), and a number that cannot be stored without becoming `NaN`/`INF` raises [`out_of_range.406`](https://json.nlohmann.me/home/exceptions/#jsonexceptionout_of_range406).
-
-One behavioral nuance is worth calling out, because a superficial test often misreads it as non-compliance: [`parse()`](https://json.nlohmann.me/api/basic_json/parse/) is strict and rejects trailing data after a value, whereas [`operator>>`](https://json.nlohmann.me/api/operator_gtgt/) follows relaxed iostream semantics — it parses a single value and leaves the stream positioned right after it. Feeding "a valid document followed by trailing bytes" through `operator>>` reports success; the same input through `parse()` is rejected. This is a documented two-API design, not a conformance gap. See [**parsing**](https://json.nlohmann.me/features/parsing/) for details.
-
 ### Character encoding

 The library supports **Unicode input** as follows:
@@ -213,38 +213,18 @@ add_custom_target(ci_test_legacycomparison
 )

 ###############################################################################
-# Validate UTF-8 with simdutf.
+# Enable brace-init copy semantics.
 ###############################################################################

-add_custom_target(ci_test_simdutf
+add_custom_target(ci_test_brace_init_copy_semantics
    COMMAND ${CMAKE_COMMAND}
    -DCMAKE_BUILD_TYPE=Debug -GNinja
-    -DJSON_BuildTests=ON -DJSON_TestSimdutf=ON
-    # simdutf needs C++17, so the library falls back to its scalar validator
-    # below that: build the suite at C++11 to cover the fallback with the macro
-    # defined, and at C++17 to run every test against simdutf itself
-    "-DJSON_TestStandards=11\;17"
-    -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_simdutf
-    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_simdutf
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_simdutf && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
-    COMMENT "Compile and test with simdutf UTF-8 validation enabled"
-)
-
-###############################################################################
-# Enable strict NUL-byte handling.
-###############################################################################
-
-add_custom_target(ci_test_strict_nul_handling
-    COMMAND ${CMAKE_COMMAND}
-    -DCMAKE_BUILD_TYPE=Debug -GNinja
-    -DJSON_BuildTests=ON -DJSON_FastTests=ON -DJSON_StrictNulHandling=ON
-    -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_strict_nul_handling
-    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_strict_nul_handling
-    # unit-testsuites contains a fixture (a "1e308" test value) that relies on the
-    # legacy NUL-as-end-of-input behavior this macro disables; exclude it here, as
-    # it is expected to fail under strict NUL handling and is out of scope for it
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_strict_nul_handling && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure -E "test-testsuites"
-    COMMENT "Compile and test with strict NUL-byte handling enabled"
+    -DJSON_BuildTests=ON -DJSON_FastTests=ON
+    -DCMAKE_CXX_FLAGS=-DJSON_BRACE_INIT_COPY_SEMANTICS=1
+    -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_brace_init_copy_semantics
+    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_brace_init_copy_semantics
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_brace_init_copy_semantics && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
+    COMMENT "Compile and test with brace-init copy semantics enabled"
 )

 ###############################################################################
@@ -262,59 +242,6 @@ add_custom_target(ci_test_noglobaludls
    COMMENT "Compile and test with global UDLs disabled"
 )

-###############################################################################
-# Disable enum serialization.
-###############################################################################
-
-add_custom_target(ci_test_disableenumserialization
-    COMMAND ${CMAKE_COMMAND}
-    -DCMAKE_BUILD_TYPE=Debug -GNinja
-    -DJSON_BuildTests=ON -DJSON_FastTests=ON -DJSON_DisableEnumSerialization=ON
-    -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_disableenumserialization
-    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_disableenumserialization
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_disableenumserialization && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
-    COMMENT "Compile and test with enum serialization disabled"
-)
-
-###############################################################################
-# Skip the multiple-inclusion library version check.
-###############################################################################
-
-# tests/src/skip_library_version_check.cpp deliberately simulates a scenario
-# (mixing two differently-versioned inclusions of the library in one
-# translation unit) that unavoidably triggers the compiler's own "macro
-# redefined" warning, so -- unlike the ci_test_* targets above -- it is
-# compiled directly here, with a modest warning set, instead of being folded
-# into the library's own -Weverything/-Werror unit test matrix.
-add_custom_target(ci_test_skiplibraryversioncheck
-    COMMAND ${CMAKE_COMMAND} -E make_directory ${PROJECT_BINARY_DIR}/skip_library_version_check
-    COMMAND ${CMAKE_CXX_COMPILER} -std=c++11 -Wall -Wextra
-        -I${PROJECT_SOURCE_DIR}/include
-        ${PROJECT_SOURCE_DIR}/tests/src/skip_library_version_check.cpp
-        -o ${PROJECT_BINARY_DIR}/skip_library_version_check/skip_library_version_check
-    COMMAND ${PROJECT_BINARY_DIR}/skip_library_version_check/skip_library_version_check
-    COMMENT "Compile and run a translation unit simulating a mismatched library version, with JSON_SKIP_LIBRARY_VERSION_CHECK defined"
-)
-
-###############################################################################
-# Disable thread-local storage.
-###############################################################################
-
-# Without thread-local storage, the copy constructor cannot bound its descent
-# and copies every object and array without the call stack. That path is
-# otherwise only reached by values nested deeper than the bound, so this target
-# is what runs the whole test suite through it.
-add_custom_target(ci_test_no_thread_local
-    COMMAND ${CMAKE_COMMAND}
-    -DCMAKE_BUILD_TYPE=Debug -GNinja
-    -DJSON_BuildTests=ON
-    -DCMAKE_CXX_FLAGS=-DJSON_NO_THREAD_LOCAL
-    -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_no_thread_local
-    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_no_thread_local
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_no_thread_local && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
-    COMMENT "Compile and test without thread-local storage"
-)
-
 ###############################################################################
 # Coverage.
 ###############################################################################
@@ -367,7 +294,7 @@ file(GLOB_RECURSE INDENT_FILES
        ${PROJECT_SOURCE_DIR}/tests/src/*.cpp
        ${PROJECT_SOURCE_DIR}/tests/src/*.hpp
        ${PROJECT_SOURCE_DIR}/tests/benchmarks/src/benchmarks.cpp
-    ${PROJECT_SOURCE_DIR}/docs/mkdocs/docs/examples/*.cpp
+    ${PROJECT_SOURCE_DIR}/docs/examples/*.cpp
 )

 set(include_dir ${PROJECT_SOURCE_DIR}/single_include/nlohmann)
@@ -5,9 +5,6 @@
 # -Wno-extra-semi-stmt            The library uses assert which triggers this warning.
 # -Wno-padded                     We do not care about padding warnings.
 # -Wno-covered-switch-default     All switches list all cases and a default case.
-# -Wno-c2y-extensions             Clang 22.1 diagnoses __COUNTER__ as a C2y extension, also in
-#                                 C++ mode. The library does not use __COUNTER__; the warnings
-#                                 all come from vendored Doctest (SECTION/TEST_CASE macros).
 # -Wno-unsafe-buffer-usage        Pervasive: the library's own low-level numeric/buffer code
 #                                 (to_chars, serializer, lexer, binary reader/writer, input
 #                                 adapters, json_pointer) plus vendored Doctest itself (~208
@@ -23,6 +20,5 @@ set(CLANG_CXXFLAGS
    -Wno-extra-semi-stmt
    -Wno-padded
    -Wno-covered-switch-default
-    -Wno-c2y-extensions
    -Wno-unsafe-buffer-usage
 )
@@ -1,58 +1,24 @@
 # generate Bazel BUILD file
-#
-# usage: cmake -P cmake/scripts/gen_bazel_build_file.cmake (or: make BUILD.bazel)
-#
-# The header list of the "json" target is derived from the files in include/. Everything else is fixed text below,
-# so edit this script rather than BUILD.bazel.

-get_filename_component(PROJECT_ROOT "${CMAKE_CURRENT_LIST_DIR}/../.." ABSOLUTE)
+set(PROJECT_ROOT "${CMAKE_CURRENT_LIST_DIR}/../..")
 set(BUILD_FILE "${PROJECT_ROOT}/BUILD.bazel")

-file(GLOB_RECURSE HEADERS LIST_DIRECTORIES false RELATIVE "${PROJECT_ROOT}" "${PROJECT_ROOT}/include/*.hpp")
-list(SORT HEADERS)
-
-set(CONTENT [=[
-load("@rules_cc//cc:cc_library.bzl", "cc_library")
-load("@rules_license//rules:license.bzl", "license")
-
-package(
-    default_applicable_licenses = [":license"],
-)
-
-exports_files([
-    "LICENSE.MIT",
-])
-
-license(
-    name = "license",
-    license_kinds = ["@rules_license//licenses/spdx:MIT"],
-    license_text = "LICENSE.MIT",
-)
+file(GLOB_RECURSE HEADERS LIST_DIRECTORIES false RELATIVE "${PROJECT_ROOT}" "include/*.hpp")

+file(WRITE "${BUILD_FILE}" [=[
 cc_library(
    name = "json",
    hdrs = [
 ]=])

 foreach(header ${HEADERS})
-    string(APPEND CONTENT "        \"${header}\",\n")
+    file(APPEND "${BUILD_FILE}" "        \"${header}\",\n")
 endforeach()

-string(APPEND CONTENT [=[
+file(APPEND "${BUILD_FILE}" [=[
    ],
    includes = ["include"],
    visibility = ["//visibility:public"],
    alwayslink = True,
 )
-
-cc_library(
-    name = "singleheader-json",
-    hdrs = [
-        "single_include/nlohmann/json.hpp",
-    ],
-    includes = ["single_include"],
-    visibility = ["//visibility:public"],
-)
 ]=])
-
-file(WRITE "${BUILD_FILE}" "${CONTENT}")
@@ -1,112 +0,0 @@
-# Shared extractor for the JSON_HEDLEY_* macro names defined in hedley.hpp.
-#
-# Every macro that hedley.hpp #defines must be #undef-ed again once json.hpp
-# has been fully processed (see include/nlohmann/detail/macro_unscope.hpp
-# and https://github.com/nlohmann/json/issues/5408). Deriving the macro list
-# straight from hedley.hpp here -- instead of hand-maintaining it in two
-# places -- means hedley_undef.hpp and the regression test that checks for
-# leaked macros can never drift apart, even after a future `make
-# update_hedley` pulls in new macros from upstream Hedley.
-#
-#   MODE=undef  (default): write hedley_undef.hpp (SPDX header, #pragma once,
-#               one #undef per macro name) -- used by `make update_hedley_undef`
-#   MODE=checks:            write one #ifdef/FAIL_CHECK/#endif per macro name,
-#               meant to be #include-d inside a TEST_CASE -- used by
-#               tests/CMakeLists.txt to (re)generate the include for
-#               tests/src/unit-no-macro-leak.cpp
-#
-# Required variables:
-#   HEDLEY_HPP  path to include/nlohmann/thirdparty/hedley/hedley.hpp
-#   OUTPUT      path of the file to (over)write
-# Optional:
-#   MODE        "undef" (default) or "checks"
-
-if(NOT DEFINED HEDLEY_HPP OR NOT DEFINED OUTPUT)
-    message(FATAL_ERROR "HEDLEY_HPP and OUTPUT must be set")
-endif()
-
-if(NOT EXISTS "${HEDLEY_HPP}")
-    message(FATAL_ERROR "Hedley header not found: ${HEDLEY_HPP}")
-endif()
-
-if(NOT DEFINED MODE)
-    set(MODE undef)
-endif()
-
-if(NOT MODE STREQUAL "undef" AND NOT MODE STREQUAL "checks")
-    message(FATAL_ERROR "MODE must be undef or checks, got: ${MODE}")
-endif()
-
-# Line-anchored, like `grep -oE "^[[:blank:]]*#[[:blank:]]*define[[:blank:]]+JSON_HEDLEY_[A-Za-z0-9_]+"`.
-# Unanchored matching would also pick up JSON_HEDLEY_* mentions inside
-# comments or string literals elsewhere in the file, which must not turn
-# into #undef lines.
-file(STRINGS "${HEDLEY_HPP}" hedley_lines)
-set(macro_names)
-foreach(line IN LISTS hedley_lines)
-    if("${line}" MATCHES "^[ \t]*#[ \t]*define[ \t]+(JSON_HEDLEY_[A-Za-z0-9_]+)")
-        list(APPEND macro_names "${CMAKE_MATCH_1}")
-    endif()
-endforeach()
-
-if(NOT macro_names)
-    message(FATAL_ERROR "No JSON_HEDLEY_* macros found in ${HEDLEY_HPP}")
-endif()
-
-list(REMOVE_DUPLICATES macro_names)
-# Lexicographic, locale-independent (ASCII-only names) -- matches `LC_ALL=C sort`.
-list(SORT macro_names COMPARE STRING)
-list(LENGTH macro_names macro_count)
-
-set(generated "")
-if(MODE STREQUAL "undef")
-    # Same banner `make update_hedley_undef` would stamp by hand, so the
-    # 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
-    # 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
-    string(APPEND generated "//     __ _____ _____ _____\n")
-    string(APPEND generated "//  __|  |   __|     |   | |  JSON for Modern C++\n")
-    string(APPEND generated "// |  |  |__   |  |  | | | |  version 3.12.0\n")
-    string(APPEND generated "// |_____|_____|_____|_|___|  https://github.com/nlohmann/json\n")
-    string(APPEND generated "//\n")
-    string(APPEND generated "// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>\n")
-    string(APPEND generated "// SPDX-License-Identifier: MIT\n")
-    # REUSE-IgnoreEnd
-    string(APPEND generated "\n")
-    string(APPEND generated "#pragma once\n")
-    string(APPEND generated "\n")
-    foreach(name IN LISTS macro_names)
-        string(APPEND generated "#undef ${name}\n")
-    endforeach()
-else()
-    string(APPEND generated "// This file is generated by cmake/scripts/gen_hedley_undef_check.cmake\n")
-    string(APPEND generated "// from include/nlohmann/thirdparty/hedley/hedley.hpp. Do not edit it by\n")
-    string(APPEND generated "// hand -- it is regenerated on every build. ${macro_count} macros checked.\n\n")
-    foreach(name IN LISTS macro_names)
-        string(APPEND generated "#ifdef ${name}\n")
-        string(APPEND generated "    FAIL_CHECK(\"${name} leaked after including nlohmann/json.hpp\");\n")
-        string(APPEND generated "#endif\n")
-    endforeach()
-endif()
-
-get_filename_component(output_dir "${OUTPUT}" DIRECTORY)
-if(output_dir)
-    file(MAKE_DIRECTORY "${output_dir}")
-endif()
-
-# Avoid rewriting the file (and busting downstream incremental rebuilds)
-# when the content has not actually changed.
-set(write_output TRUE)
-if(EXISTS "${OUTPUT}")
-    file(READ "${OUTPUT}" existing_content)
-    if(existing_content STREQUAL generated)
-        set(write_output FALSE)
-    endif()
-endif()
-if(write_output)
-    file(WRITE "${OUTPUT}" "${generated}")
-endif()
@@ -49,7 +49,7 @@ Unlike the [`parse()`](parse.md) function, this function neither throws an excep
 :   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.

    - a custom sentinel type for C++20 ranges
-    - `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
+    - `std::counted_iterator` with a different sentinel type

 ## Parameters

@@ -90,10 +90,6 @@ Linear in the length of the input. The parser is a predictive LL(1) parser.

 A UTF-8 byte order mark is silently ignored.

-By default, a `'\0'` (NUL) byte anywhere in the input is treated as end of input, rather than as an ordinary (and,
-outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-bytes-in-the-input) for details and the
-[`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) macro to opt into rejecting it instead.
-
 ## Examples

 ??? example
@@ -115,8 +111,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
 - [parse](parse.md) - deserialize from a compatible input
 - [sax_parse](sax_parse.md) - parse input using the SAX interface
 - [operator>>](../operator_gtgt.md) - deserialize from stream
- [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
-  instead of treating it as end of input

 ## Version history

@@ -126,8 +120,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
 - Added `ignore_trailing_commas` in version 3.13.0.
 - 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.
- `JSON_STRICT_NUL_HANDLING` added in version 3.13.0 to optionally reject a NUL byte in the input instead of treating
-  it as end of input; planned to become the default in version 4.0.0.

 !!! warning "Deprecation"

@@ -14,11 +14,7 @@ To store objects in C++, a type is defined by the template parameters explained
 ## Template parameters

 `ArrayType`
-:   container type to store arrays. It must be a vector-like container: the library uses `operator[]`, `at()`, and
-    `resize()`, and requires random-access iterators. `#!cpp std::vector` and `#!cpp std::deque` qualify;
-    `#!cpp std::list` does not. See
-    [Template Parameter Requirements](../../features/types/template_parameters.md#arraytype) for the full list of
-    requirements.
+:   container type to store arrays (e.g., `std::vector` or `std::list`)

 `AllocatorType`
 :   the allocator to use for objects (e.g., `std::allocator`)
@@ -70,4 +66,3 @@ Arrays are stored as pointers in a `basic_json` type. That is, for any access to
 ## Version history

 - Added in version 1.0.0.
- Made `capacity()` optional, so that array types such as `#!cpp std::deque` can be used, in version 3.13.0.
@@ -13,8 +13,9 @@ is compatible with both of the binary data formats that use binary subtyping, (t
 incompatible with each other, and it is up to the user to translate between them). The subtype is added to `BinaryType`
 via the helper type [byte_container_with_subtype](../byte_container_with_subtype/index.md).

-[CBOR's RFC 8949](https://www.rfc-editor.org/rfc/rfc8949.html#section-3.1) describes this type as:
-> Major type 2: A byte string. The number of bytes in the string is equal to the argument.
+[CBOR's RFC 7049](https://tools.ietf.org/html/rfc7049) describes this type as:
+> Major type 2: a byte string. The string's length in bytes is represented following the rules for positive integers
+> (major type 0).

 [MessagePack's documentation on the bin type
 family](https://github.com/msgpack/msgpack/blob/master/spec.md#bin-format-family) describes this type as:
@@ -42,9 +43,7 @@ represent a byte array in modern C++.
    `value_type` must additionally be exactly one byte wide (e.g., `std::uint8_t`/`char`/`std::byte`): the binary
    serializers (CBOR, MessagePack, BSON, UBJSON) read and write the container's raw bytes via
    `reinterpret_cast`, which is only correct for byte-sized elements -- a container like
-    `#!cpp std::vector<std::intptr_t>` will not work as `BinaryType`. The elements must be stored contiguously, and
-    the binary readers additionally require `resize()` and `operator[]`. See
-    [Template Parameter Requirements](../../features/types/template_parameters.md#binarytype) for the full list.
+    `#!cpp std::vector<std::intptr_t>` will not work as `BinaryType`.

 ## Notes

@@ -52,11 +51,6 @@ represent a byte array in modern C++.

 The default values for `BinaryType` is `#!cpp std::vector<std::uint8_t>`.

-#### Supported byte types
-
-`#!cpp std::vector<std::uint8_t>`, `#!cpp std::vector<char>`, and `#!cpp std::vector<std::byte>` are supported.
-Regardless of which of them is configured, [`dump`](dump.md) writes the bytes as the numbers 0..255.
-
 #### Custom BinaryType behavior

 When a custom `BinaryType` is configured (other than the default `#!cpp std::vector<std::uint8_t>`), you can assign
@@ -133,6 +127,3 @@ type `#!cpp binary_t*` must be dereferenced.
 ## Version history

 - Added in version 3.8.0. Changed the type of subtype to `std::uint64_t` in version 3.10.0.
- Fixed [`dump`](dump.md), [`std::hash`](std_hash.md), and [`to_ubjson`](to_ubjson.md) for byte types that are not
-  integers (e.g., `#!cpp std::byte`) in version 3.13.0. `dump` now writes the bytes of a signed byte type (e.g.,
-  `#!cpp char`) as 0..255 rather than as negative numbers.
@@ -11,14 +11,6 @@ literals `#!json true` and `#!json false`.

 To store boolean values in C++, a type is defined by the template parameter  `BooleanType` which chooses the type to use.

-## Template parameters
-
-`BooleanType`
-:   the type to store booleans. As it is stored directly inside a `basic_json` value (in a union), it must be a
-    trivially default-constructible, trivially copyable, and trivially destructible type that is convertible to and
-    from `#!cpp bool`. See
-    [Template Parameter Requirements](../../features/types/template_parameters.md#booleantype).
-
 ## Notes

 #### Default type
@@ -43,17 +43,6 @@ Strong guarantee: if an exception is thrown, there are no changes to any JSON va
 Throws [`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316) if a string stored inside the JSON value
 is not UTF-8 encoded and `error_handler` is set to `strict`

-!!! warning "Serializing untrusted input"
-
-    When serializing values that may contain invalid or untrusted UTF-8 (e.g., bytes taken directly from network
-    input), `dump()` throws [`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316) in the default
-    `strict` mode. To serialize such data without throwing, pass
-    [`error_handler_t::replace`](error_handler_t.md) (substitutes U+FFFD) or
-    [`error_handler_t::ignore`](error_handler_t.md). Callers that serialize untrusted input on a crash-sensitive path
-    should either choose a non-strict error handler or wrap `dump()` in a `#!cpp try`/`#!cpp catch`.
-
-    See the [FAQ](../../home/faq.md#serializing-untrusted-or-invalid-utf-8) for details.
-
 ## Complexity

 Linear.
@@ -36,10 +36,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
 :   a compatible iterator type

 `SentinelType`
-:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
-
-    - a custom sentinel type for C++20 ranges
-    - `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
+:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
+    custom sentinel type for C++20 ranges

 ## Parameters

@@ -36,10 +36,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
 :   a compatible iterator type

 `SentinelType`
-:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
-
-    - a custom sentinel type for C++20 ranges
-    - `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
+:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
+    custom sentinel type for C++20 ranges

 ## Parameters

@@ -39,10 +39,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
 :   a compatible iterator type

 `SentinelType`
-:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
-
-    - a custom sentinel type for C++20 ranges
-    - `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
+:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
+    custom sentinel type for C++20 ranges

 ## Parameters

@@ -36,10 +36,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
 :   a compatible iterator type

 `SentinelType`
-:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
-
-    - a custom sentinel type for C++20 ranges
-    - `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
+:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
+    custom sentinel type for C++20 ranges

 ## Parameters

@@ -36,10 +36,8 @@ The exact mapping and its limitations are described on a [dedicated page](../../
 :   a compatible iterator type

 `SentinelType`
-:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.
-
-    - a custom sentinel type for C++20 ranges
-    - `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
+:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance a
+    custom sentinel type for C++20 ranges

 ## Parameters

@@ -35,10 +35,6 @@ class basic_json;
 | `BinaryType`         | type for binary arrays                                                    | [`binary_t`](binary_t.md)                   |
 | `CustomBaseClass`    | extension point for user code                                             | [`json_base_class_t`](json_base_class_t.md) |

-The library imposes a number of requirements on these types that are not expressed as C++ concepts, such as the
-container operations `object_t` and `array_t` must provide, or the fact that `StringType` must be `char`-based. They
-are collected in [Template Parameter Requirements](../../features/types/template_parameters.md).
-
 ## Specializations

 - [**json**](../json.md) - default specialization
@@ -88,8 +88,6 @@ Strong exception safety: if an exception occurs, the original value stays intact
      do not belong to the same JSON value; example: `"iterators do not fit"`
    - Throws [`invalid_iterator.211`](../../home/exceptions.md#jsonexceptioninvalid_iterator211) if `first` or `last`
      are iterators into container for which insert is called; example: `"passed iterators may not belong to container"`
-    - Throws [`invalid_iterator.202`](../../home/exceptions.md#jsonexceptioninvalid_iterator202) if `first` or `last`
-      do not point to an array; example: `"iterators first and last must point to arrays"`
 4. The function can throw the following exceptions:
    - Throws [`type_error.309`](../../home/exceptions.md#jsonexceptiontype_error309) if called on JSON values other than
      arrays; example: `"cannot use insert() with string"`
@@ -21,11 +21,8 @@ The default value for `CustomBaseClass` is `void`. In this case, an

 #### Limitations

-The type `CustomBaseClass` has to be a default-constructible, non-`final` class.
+The type `CustomBaseClass` has to be a default-constructible class.
 `basic_json` only supports copy/move construction/assignment if `CustomBaseClass` does so as well.
-A `CustomBaseClass` with non-static data members forfeits `basic_json`'s
-[standard layout](https://en.cppreference.com/w/cpp/named_req/StandardLayoutType) guarantee. See
-[Template Parameter Requirements](../../features/types/template_parameters.md#custombaseclass).

 ## Examples

@@ -19,12 +19,6 @@ using json_serializer = JSONSerializer<T, SFINAE>;

 The default values for `json_serializer` is [`adl_serializer`](../adl_serializer/index.md).

-#### Requirements
-
-A custom serializer must provide `#!cpp static void to_json(basic_json&, T)` for every type it serializes, and either
-`#!cpp static void from_json(const basic_json&, T&)` or `#!cpp static T from_json(const basic_json&)` for every type it
-deserializes. See [Template Parameter Requirements](../../features/types/template_parameters.md#jsonserializer).
-
 ## Examples

 ??? example
@@ -20,16 +20,6 @@ used.
 To store floating-point numbers in C++, a type is defined by the template parameter `NumberFloatType` which chooses the
 type to use.

-## Template parameters
-
-`NumberFloatType`
-:   the type to store floating-point numbers. Parsing and serialization are implemented in terms of
-    `#!cpp std::strtof`/`#!cpp std::strtod`/`#!cpp std::strtold` and `#!cpp std::snprintf`, so the type must be
-    `#!cpp float`, `#!cpp double`, or `#!cpp long double`. The
-    [binary formats](../../features/binary_formats/index.md) additionally require `#!cpp float` or `#!cpp double`,
-    because they have no encoding for `#!cpp long double`. See
-    [Template Parameter Requirements](../../features/types/template_parameters.md#numberfloattype).
-
 ## Notes

 #### Default type
@@ -20,13 +20,6 @@ used.
 To store integer numbers in C++, a type is defined by the template parameter `NumberIntegerType` which chooses the type
 to use.

-## Template parameters
-
-`NumberIntegerType`
-:   the type to store signed integers. It must be a **signed integral** type (`#!cpp std::is_integral`) with a
-    `#!cpp std::numeric_limits` specialization, and it is stored directly inside a `basic_json` value. See
-    [Template Parameter Requirements](../../features/types/template_parameters.md#numberintegertype-and-numberunsignedtype).
-
 ## Notes

 #### Default type
@@ -20,14 +20,6 @@ used.
 To store unsigned integer numbers in C++, a type is defined by the template parameter `NumberUnsignedType` which chooses
 the type to use.

-## Template parameters
-
-`NumberUnsignedType`
-:   the type to store unsigned integers. It must be an **unsigned integral** type (`#!cpp std::is_integral`) with a
-    `#!cpp std::numeric_limits` specialization, and it must be able to represent the absolute value of every
-    [`number_integer_t`](number_integer_t.md) value. See
-    [Template Parameter Requirements](../../features/types/template_parameters.md#numberintegertype-and-numberunsignedtype).
-
 ## Notes

 #### Default type
@@ -30,5 +30,3 @@ and [`default_object_comparator_t`](default_object_comparator_t.md) otherwise.
 - Added in version 3.0.0.
 - Changed to be conditionally defined as `#!cpp typename object_t::key_compare` or `default_object_comparator_t` in
  version 3.11.0.
- Fixed the fallback to `default_object_comparator_t`, which previously failed to compile for object types without a
-  `key_compare` member type, in version 3.13.0.
@@ -18,11 +18,7 @@ To store objects in C++, a type is defined by the template parameters described
 ## Template parameters

 `ObjectType`
-:   the container to store objects. Its template parameters must have the same order and meaning as those of
-    `std::map`; in particular, the third parameter is a comparator. `#!cpp std::unordered_map`, whose third parameter
-    is a hash function, therefore needs an adapter -- see
-    [Template Parameter Requirements](../../features/types/template_parameters.md#objecttype) for the full list of
-    requirements, an adapter example, and the containers that are known to work.
+:   the container to store objects (e.g., `std::map` or `std::unordered_map`)

 `StringType`
 :   the type of the keys or names (e.g., `std::string`). The comparison function `std::less<StringType>` is used to
@@ -126,4 +122,3 @@ the object is silently converted as an array of key-value pairs, which is incorr
 ## Version history

 - Added in version 1.0.0.
- Allowed object types whose `erase(iterator)` returns `#!cpp void` in version 3.13.0.
@@ -48,7 +48,7 @@ static basic_json parse(IteratorType first, SentinelType last,
 :   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for instance.

    - a custom sentinel type for C++20 ranges
-    - `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
+    - `std::counted_iterator` with a different sentinel type

 ## Parameters

@@ -103,10 +103,6 @@ A UTF-8 byte order mark is silently ignored.
 Invalid Unicode escapes and unpaired surrogates in the input are reported as
 [`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101) with a detailed message.

-By default, a `'\0'` (NUL) byte anywhere in the input is treated as end of input, rather than as an ordinary (and,
-outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-bytes-in-the-input) for details and the
-[`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) macro to opt into rejecting it instead.
-
 ## Examples

 ??? example "Parsing from a character array"
@@ -240,8 +236,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
 - [accept](accept.md) - check if the input is valid JSON
 - [sax_parse](sax_parse.md) - parse input using the SAX interface
 - [operator>>](../operator_gtgt.md) - deserialize from stream
- [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
-  instead of treating it as end of input

 ## Version history

@@ -252,8 +246,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
 - Added `ignore_trailing_commas` in version 3.13.0.
 - 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.
- `JSON_STRICT_NUL_HANDLING` added in version 3.13.0 to optionally reject a NUL byte in the input instead of treating
-  it as end of input; planned to become the default in version 4.0.0.

 !!! warning "Deprecation"

@@ -29,14 +29,7 @@ Discarding a value (i.e., returning `#!cpp false`) has different effects dependi
 called:

 - Discarded values in structured types are skipped. That is, the parser will behave as if the discarded value was never
-  read. This holds for every value type and for both kinds of parent: a discarded element is removed from the
-  surrounding array, and a discarded member is removed from the surrounding object together with its key.
- Arrays and objects can be discarded either at their `parse_event_t::array_start`/`parse_event_t::object_start` event
-  or at their `parse_event_t::array_end`/`parse_event_t::object_end` event, and both remove the whole value. Discarding
-  it at the start event also means the callback is called neither for the content of the value nor for its matching end
-  event.
- Discarding a `parse_event_t::key` event discards the whole object member. The callback is still called for the
-  associated value, but its return value has no further effect.
+  read.
 - In case a value outside a structured type is skipped, it is replaced with `null`. This case happens if the top-level
  element is skipped.

@@ -56,7 +49,7 @@ called:
 ## Return value

 Whether the JSON value which called the function during parsing should be kept (`#!cpp true`) or not (`#!cpp false`). In
-the latter case, it is skipped completely, or replaced by `null` if it is the top-level value.
+the latter case, it is either skipped completely or replaced by an empty discarded object.

 ## Examples

@@ -75,21 +68,6 @@ the latter case, it is skipped completely, or replaced by `null` if it is the to
    --8<-- "examples/parse__string__parser_callback_t.output"
    ```

-??? example
-
-    The example below shows where discarded values are removed. The array and the number are discarded in different
-    ways, but in each case the parse result contains neither the value nor its key.
-
-    ```cpp
-    --8<-- "examples/parser_callback_t.cpp"
-    ```
-
-    Output:
-
-    ```json
-    --8<-- "examples/parser_callback_t.output"
-    ```
-
 ## See also

 - [parse](parse.md) deserialize from a compatible input
@@ -98,5 +76,3 @@ the latter case, it is skipped completely, or replaced by `null` if it is the to
 ## Version history

 - Added in version 1.0.0.
- Fixed in version 3.13.0 to also remove discarded values from a parent object; before, discarding an array or a value
-  stored under an object key left a discarded member behind, which made the parse result serialize to invalid JSON.
@@ -34,10 +34,6 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
  ("add", "remove", "move")
 - Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
  location has a parent that is neither an object nor an array.
- Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
-  location has a parent that is neither an object nor an array.
- Throws [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) if a "move" operation's "from"
-  location is a proper prefix of its "path" location.
 - Throws [`other_error.501`](../../home/exceptions.md#jsonexceptionother_error501) if "test" operation was
  unsuccessful.

@@ -79,7 +75,3 @@ is thrown. In any case, the original value is not changed: the patch is applied
 - Added in version 2.0.0.
 - Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
  target location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) and stopped silently ignoring a "remove" operation whose target
-  location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) and rejected a "move" operation whose "from" location is a proper
-  prefix of its "path" location instead of silently producing a corrupted result in version 3.13.0.
@@ -30,10 +30,6 @@ No guarantees, value may be corrupted by an unsuccessful patch operation.
  ("add", "remove", "move")
 - Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
  location has a parent that is neither an object nor an array.
- Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
-  location has a parent that is neither an object nor an array.
- Throws [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) if a "move" operation's "from"
-  location is a proper prefix of its "path" location.
 - Throws [`other_error.501`](../../home/exceptions.md#jsonexceptionother_error501) if "test" operation was
  unsuccessful.

@@ -76,7 +72,3 @@ function throws an exception.
 - Added in version 3.11.0.
 - Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
  target location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) and stopped silently ignoring a "remove" operation whose target
-  location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) and rejected a "move" operation whose "from" location is a proper
-  prefix of its "path" location instead of silently producing a corrupted result in version 3.13.0.
@@ -48,10 +48,7 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
    with a size of 1, 2, or 4 bytes (interpreted respectively as UTF-8, UTF-16, and UTF-32)

 `SentinelType`
-:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for overload (2), for instance.
-
-    - a custom sentinel type for C++20 ranges
-    - `std::default_sentinel_t`, when `IteratorType` is `std::counted_iterator`
+:   defaults to `IteratorType`; may be a different type comparable to `IteratorType` via `operator!=`, for overload (2)

 `SAX`
 :   a class fulfilling the SAX event listener interface; see [`json_sax`](../json_sax/index.md)
@@ -69,9 +66,7 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
     [`input_format_t`](input_format_t.md) for more information

 `strict` (in)
-:   whether the input has to be consumed completely (optional, `#!cpp true` by default); when `#!cpp false` and the
-    input is a `#!cpp std::istream`, the character that terminates a number is consumed unless
-    [`JSON_PRECISE_STREAM_POSITION`](../macros/json_precise_stream_position.md) is defined to `1`; see [`operator>>`](../operator_gtgt.md#notes)
+:   whether the input has to be consumed completely (optional, `#!cpp true` by default)

 `ignore_comments` (in)
 :   whether comments should be ignored and treated like whitespace (`#!cpp true`) or yield a parse error
@@ -138,8 +133,6 @@ A UTF-8 byte order mark is silently ignored.
 - Added `ignore_trailing_commas` in version 3.13.0.
 - 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.
- `JSON_PRECISE_STREAM_POSITION` added in version 3.13.0 to optionally leave a `#!cpp std::istream` positioned right
-  after the parsed value when `strict` is `#!cpp false`.

 !!! warning "Deprecation"

@@ -23,11 +23,6 @@ JSON class into byte-sized characters during deserialization.
    `StringType`. To work with wide-character data, convert it to/from UTF-8 at the boundary instead -- see the
    FAQ's [wide string handling](../../home/faq.md#wide-string-handling) section for a conversion recipe.

-    Beyond the character type, the library expects a substantial part of the `#!cpp std::string` interface (contiguous
-    null-terminated `data()`, `substr()`, `find()`, `append()`, ...). See
-    [Template Parameter Requirements](../../features/types/template_parameters.md#stringtype) for the full list and
-    for the string types that are known to work.
-
 ## Notes

 #### Default type
@@ -83,5 +78,3 @@ and an example.
 ## Version history

 - Added in version 1.0.0.
- Removed the requirement that `string_t` be implicitly convertible from `#!cpp std::string`, which the BSON writer and
-  the UBJSON reader relied on, in version 3.13.0.
@@ -34,14 +34,10 @@ void swap(typename binary_t::container_type& other);
 ```

 1. Exchanges the contents of the JSON value with those of `other`. Does not invoke any move, copy, or swap operations on
-   individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. If macro
-   [`JSON_DIAGNOSTIC_POSITIONS`](../macros/json_diagnostic_positions.md) is defined to `#!cpp 1`, the
-   [`start_pos()`](start_pos.md)/[`end_pos()`](end_pos.md) diagnostic positions are exchanged along with the value.
+   individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. 
 2. Exchanges the contents of the JSON value from `left` with those of `right`. Does not invoke any move, copy, or swap
   operations on individual elements. All iterators and references remain valid. The past-the-end iterator is
-   invalidated. Implemented as a friend function callable via ADL. If macro
-   [`JSON_DIAGNOSTIC_POSITIONS`](../macros/json_diagnostic_positions.md) is defined to `#!cpp 1`, the
-   [`start_pos()`](start_pos.md)/[`end_pos()`](end_pos.md) diagnostic positions are exchanged along with the value.
+   invalidated. Implemented as a friend function callable via ADL.
 3. Exchanges the contents of a JSON array with those of `other`. Does not invoke any move, copy, or swap operations on
   individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. 
 4. Exchanges the contents of a JSON object with those of `other`. Does not invoke any move, copy, or swap operations on
@@ -52,11 +52,6 @@ optional, `#!cpp bjdata_version_t::draft2` by default.

 Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

-## Exceptions
-
- Throws [`other_error.502`](../../home/exceptions.md#jsonexceptionother_error502) if `use_type` is true and `use_size`
-  is false.
-
 ## Complexity

 Linear in the size of the JSON value `j`.
@@ -40,15 +40,10 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
  is not an object; example: `"to serialize to BSON, top-level type must be object, but is string"`
 - Throws [`out_of_range.409`](../../home/exceptions.md#jsonexceptionout_of_range409) if a key in the JSON object contains
  a null byte (code point U+0000); example: `"BSON key cannot contain code point U+0000 (at byte 2)"`
- Throws [`out_of_range.412`](../../home/exceptions.md#jsonexceptionout_of_range412) if the length of a document, array,
-  string, or binary value exceeds the range of the 32-bit BSON length field; example:
-  `"BSON length 2147483661 exceeds maximum of 2147483647"`

 ## Complexity

-Proportional to the size of the JSON value `j` multiplied by its maximum nesting
-depth, `O(n × d)`. BSON length prefixes are computed recursively before nested
-values are written.
+Linear in the size of the JSON value `j`.

 ## Examples

@@ -45,11 +45,6 @@ The exact mapping and its limitations are described on a [dedicated page](../../

 Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

-## Exceptions
-
- Throws [`other_error.502`](../../home/exceptions.md#jsonexceptionother_error502) if `use_type` is true and `use_size`
-  is false.
-
 ## Complexity

 Linear in the size of the JSON value `j`.
@@ -37,14 +37,7 @@ Linear in the size of the JSON value.
 ## Notes

 Empty objects and arrays are flattened by [`flatten()`](flatten.md) to `#!json null` values and cannot unflattened to
-their original type.
-
-A flattened array and a flattened object whose keys are array indices are indistinguishable, because both are
-described by the same JSON pointers. A value is therefore restored as an array if and only if one of its keys is the
-reference token `0`, and as an object otherwise: `#!json {"2": 1}` is restored unchanged, whereas `#!json {"0": 1}` is
-restored as `#!json [1]`. This decision does not depend on the order in which the flattened object is iterated.
-
-Apart from these two cases, for a JSON value `j`, the following is always true:
+their original type. Apart from this example, for a JSON value `j`, the following is always true:
 `#!cpp j == j.flatten().unflatten()`.

 ## Examples
@@ -70,4 +63,3 @@ Apart from these two cases, for a JSON value `j`, the following is always true:
 ## Version history

 - Added in version 2.0.0.
- Made the array/object decision independent of the object's iteration order in version 3.13.0.
@@ -14,13 +14,6 @@ header. See also the [macro overview page](../../features/macros.md).
 - [**JSON_DIAGNOSTIC_POSITIONS**](json_diagnostic_positions.md) - access positions of elements
 - [**JSON_NOEXCEPTION**](json_noexception.md) - switch off exceptions

-## Parsing
-
- [**JSON_PRECISE_STREAM_POSITION**](json_precise_stream_position.md) - opt in to leaving an input stream positioned
-  right after a parsed number
- [**JSON_STRICT_NUL_HANDLING**](json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input instead of
-  treating it as end of input
-
 ## Language support

 - [**JSON_HAS_CPP_11**<br>**JSON_HAS_CPP_14**<br>**JSON_HAS_CPP_17**<br>**JSON_HAS_CPP_20**](json_has_cpp_11.md) - set supported C++ standard
@@ -29,10 +22,8 @@ header. See also the [macro overview page](../../features/macros.md).
 - [**JSON_HAS_STD_FORMAT**](json_has_std_format.md) - control `std::format`/`std::formatter` support
 - [**JSON_HAS_THREE_WAY_COMPARISON**](json_has_three_way_comparison.md) - control 3-way comparison support
 - [**JSON_NO_IO**](json_no_io.md) - switch off functions relying on certain C++ I/O headers
- [**JSON_NO_THREAD_LOCAL**](json_no_thread_local.md) - switch off the use of `thread_local` storage
 - [**JSON_SKIP_UNSUPPORTED_COMPILER_CHECK**](json_skip_unsupported_compiler_check.md) - do not warn about unsupported compilers
 - [**JSON_USE_GLOBAL_UDLS**](json_use_global_udls.md) - place user-defined string literals (UDLs) into the global namespace
- [**JSON_USE_SIMDUTF**](json_use_simdutf.md) - use the simdutf library to accelerate UTF-8 validation

 ## Library version

@@ -38,28 +38,6 @@ The default value is `0` (disabled — existing behavior is preserved).

    This macro must be defined **before** including `<nlohmann/json.hpp>`. Defining it after the include has no effect.

-!!! warning "Applies to every single-element list"
-
-    The macro does not only affect a single JSON value in braces. **Any** single-element braced list is treated as its
-    element, so it no longer creates a one-element array:
-
-    ```cpp
-    json j1 = {1};       // 1, not [1]
-    json j2 = {"text"};  // "text", not ["text"]
-    json j3 = {{1, 2}};  // [1,2], not [[1,2]]
-    ```
-
-    Code that relies on these producing arrays must use `json::array()` instead (see below). Lists with more than one
-    element, and a single `[string, value]` pair such as `{{"key", "value"}}`, which still creates an object, are not
-    affected. The library's own conversions are not affected either: for example, `std::tuple<int>{5}` still becomes
-    `[5]`.
-
-!!! note "ABI compatibility"
-
-    The value of this macro is encoded in the [namespace](../../features/namespace.md) (tag `_bics`), resulting in
-    distinct symbol names. Translation units compiled with and without it can therefore be linked into the same program
-    without One Definition Rule (ODR) violations, but they cannot exchange instances of library types.
-
 !!! tip "Workaround without the macro"

    To explicitly create a single-element array without enabling this macro, use `json::array()`:
@@ -38,8 +38,7 @@ When the macro is not defined, the library will define it to its default value.

    Diagnostic messages can also be controlled with the CMake option
    [`JSON_Diagnostics`](../../integration/cmake.md#json_diagnostics) (`OFF` by default)
-    which defines `JSON_DIAGNOSTICS` accordingly. Note this only applies when building the
-    library from source — see the pre-installed-package caveat on that page.
+    which defines `JSON_DIAGNOSTICS` accordingly.

 ## Examples

@@ -1,47 +0,0 @@
-# JSON_NO_THREAD_LOCAL
-
-```cpp
-#define JSON_NO_THREAD_LOCAL
-```
-
-When defined, the library does not use `#!cpp thread_local` storage. This is relevant for the few environments whose
-toolchain does not support it.
-
-The copy constructor copies the first levels of a value by copying the containers, which copy their elements, and
-completes whatever is nested deeper than that without the call stack, so that copying a value cannot exhaust the stack
-however deeply it is nested. It counts the levels it has descended into in a `#!cpp thread_local` variable, as a counter
-shared between threads would be raced.
-
-Without that counter, no descent can be bounded safely, so objects and arrays are copied without the call stack right
-away. Copying keeps working exactly as it does otherwise - the same values come out, and deeply nested values are copied
-just as safely - but copying is slower, because the containers no longer copy themselves. Copying the benchmark
-documents takes 9% (`canada.json`) to 34% (`twitter.json`) longer; values built mostly from objects are affected the
-most.
-
-## Default definition
-
-By default, `#!cpp JSON_NO_THREAD_LOCAL` is not defined.
-
-```cpp
-#undef JSON_NO_THREAD_LOCAL
-```
-
-The library defines it by itself for Clang targeting MinGW, which does not survive the `#!cpp thread_local` storage:
-copying a value segfaults there, with both old and current Clang versions, while GCC targeting MinGW is unaffected.
-
-## Examples
-
-??? example
-
-    The code below forces the library not to use `#!cpp thread_local` storage.
-
-    ```cpp
-    #define JSON_NO_THREAD_LOCAL 1
-    #include <nlohmann/json.hpp>
-
-    ...
-    ```
-
-## Version history
-
- Added in version 3.12.1.
@@ -1,131 +0,0 @@
-# JSON_PRECISE_STREAM_POSITION
-
-```cpp
-#define JSON_PRECISE_STREAM_POSITION /* value */
-```
-
-When defined to `1`, [`operator>>`](../operator_gtgt.md) and [`sax_parse`](../basic_json/sax_parse.md) with
-`strict = false` leave a `#!cpp std::istream` positioned right after the parsed value for every value type. By default,
-the character that terminates a number is consumed as well.
-
-The macro only affects reading from a `#!cpp std::istream` when the rest of the stream is not required to be consumed.
-[`parse`](../basic_json/parse.md), [`accept`](../basic_json/accept.md), and all other inputs (strings, iterators,
-containers, `#!cpp FILE*`) are never affected.
-
-## Default definition
-
-The default value is `0` (disabled — existing behavior is preserved).
-
-```cpp
-#define JSON_PRECISE_STREAM_POSITION 0
-```
-
-## Notes
-
-!!! note "Background"
-
-    A number is the only JSON value whose end can be detected solely by reading the character that follows it. By
-    default, that character is consumed and not put back, so the stream is left one byte too far after a number, and
-    only after a number:
-
-    ```cpp
-    std::istringstream input("1true");
-    json j;
-    input >> j;  // j == 1, but the stream now starts at "rue"
-    ```
-
-    With this macro, the character is only looked at and left in the stream, so the stream starts at `true`. This
-    does not require the stream buffer to support putting a character back.
-
-    This was not changed unconditionally, because code can depend on the consumed character, even unknowingly (see
-    [#5340](https://github.com/nlohmann/json/issues/5340)). Both of the following work by default only because the
-    character after each number is swallowed, and behave differently with this macro:
-
-    ```cpp
-    std::istringstream input("1,2,3");
-    json j1, j2, j3;
-    input >> j1 >> j2 >> j3;  // default: 1, 2, 3
-                              // with the macro: throws parse_error.101 at the ','
-    ```
-
-    ```cpp
-    std::istringstream input("42\nfoo");
-    json j;
-    std::string line;
-    input >> j;
-    std::getline(input, line);  // default: "foo"
-                                // with the macro: "" (like after reading an int with >>)
-    ```
-
-    In both cases, the behavior with the macro is what you already get today when the value is not a number: `"a","b"`
-    fails at the `,`, and `std::getline` after `{}` returns an empty string. This macro offers an opt-in path to
-    the consistent behavior ahead of version 4.0.0, where it is planned to become the default.
-
-!!! warning "Opt-in only"
-
-    This macro must be defined **before** including `<nlohmann/json.hpp>`. Defining it after the include has no
-    effect.
-
-!!! note "ABI compatibility"
-
-    The value of this macro is encoded in the [namespace](../../features/namespace.md) (tag `_psp`), resulting in
-    distinct symbol names. Translation units compiled with and without it can therefore be linked into the same program
-    without One Definition Rule (ODR) violations, but they cannot exchange instances of library types.
-
-!!! tip "Workaround without the macro"
-
-    Separate the values in the stream with whitespace. The character consumed after a number is then the separator,
-    and whitespace before the next value is skipped anyway.
-
-## Examples
-
-??? example "Default behavior (macro not defined)"
-
-    Without the macro, the character after a number is consumed:
-
-    ```cpp
-    #include <iostream>
-    #include <sstream>
-    #include <nlohmann/json.hpp>
-
-    using json = nlohmann::json;
-
-    int main()
-    {
-        std::istringstream input("1true");
-        json j1, j2;
-        input >> j1;  // j1 == 1
-        input >> j2;  // throws parse_error.101: the stream now starts at "rue"
-    }
-    ```
-
-??? example "Opt-in precise stream position (macro defined to 1)"
-
-    With the macro, the stream is positioned right after the number:
-
-    ```cpp
-    #define JSON_PRECISE_STREAM_POSITION 1
-    #include <iostream>
-    #include <sstream>
-    #include <nlohmann/json.hpp>
-
-    using json = nlohmann::json;
-
-    int main()
-    {
-        std::istringstream input("1true");
-        json j1, j2;
-        input >> j1;  // j1 == 1
-        input >> j2;  // j2 == true
-    }
-    ```
-
-## See also
-
- [**operator>>**](../operator_gtgt.md) - deserialize from stream
- [**sax_parse**](../basic_json/sax_parse.md) - generate SAX events
-
-## Version history
-
- Added in version 3.13.0.
- Planned to become the default (with the macro removed) in version 4.0.0.
@@ -1,126 +0,0 @@
-# JSON_STRICT_NUL_HANDLING
-
-```cpp
-#define JSON_STRICT_NUL_HANDLING /* value */
-```
-
-When defined to `1`, a `'\0'` (NUL) byte in JSON text input is rejected with `parse_error.101`, like any other
-unexpected byte, instead of being silently treated as end of input.
-
-The macro only affects the JSON text parser ([`parse`](../basic_json/parse.md), [`accept`](../basic_json/accept.md),
-[`sax_parse`](../basic_json/sax_parse.md), and [`operator>>`](../operator_gtgt.md)). There are three cases where a NUL
-byte is still not rejected:
-
- The binary formats ([`from_bjdata`](../basic_json/from_bjdata.md), [`from_bson`](../basic_json/from_bson.md),
-  [`from_cbor`](../basic_json/from_cbor.md), [`from_msgpack`](../basic_json/from_msgpack.md),
-  [`from_ubjson`](../basic_json/from_ubjson.md)) are never affected: there, `0x00` is ordinary data.
- A bare `const char*` pointer has no length of its own, so its length is still determined with `strlen()`. The first
-  NUL byte therefore still marks the end of the input, and nothing after it is read.
- One trailing `'\0'` at the end of a `char` array (e.g., a string literal) is trimmed; see the warning below.
-
-## Default definition
-
-The default value is `0` (disabled — existing behavior is preserved).
-
-```cpp
-#define JSON_STRICT_NUL_HANDLING 0
-```
-
-## Notes
-
-!!! note "Background"
-
-    By default, a `'\0'` byte anywhere in the input is treated the same as the real end of the input, rather than as
-    an ordinary (and, outside of a string, invalid) byte. Everything from that byte onward is silently ignored,
-    without a parse error - including further, otherwise well-formed JSON:
-
-    ```cpp
-    json::parse(std::string("123") + '\0');          // == 123, no error
-    json::parse(std::string("123") + '\0' + "true"); // == 123, the "true" is silently ignored too
-    ```
-
-    This falls out of the same convention used when no explicit input length is given at all: parsing from a
-    `const char*` already stops at the first NUL byte via `strlen()`, since a bare pointer has no length of its own.
-    The library applies that same NUL-terminated-C-string convention uniformly, rather than only when a length is
-    genuinely unavailable - so a `std::string`, iterator range, or container whose content happens to include a NUL
-    byte is affected the same way a raw `const char*` would be (see the
-    [FAQ entry](../../home/faq.md#nul-bytes-in-the-input) for a fuller explanation).
-
-    This was not fixed unconditionally, because doing so is backwards-incompatible for any caller who happens to
-    depend on the current behavior - even unknowingly, for instance because their input already contains trailing
-    padding they never noticed was being discarded (see [#5530](https://github.com/nlohmann/json/issues/5530)).
-    This macro instead offers an opt-in path to the corrected behavior ahead of version 4.0.0, where it is planned to
-    become the default.
-
-!!! warning "Opt-in only"
-
-    This macro must be defined **before** including `<nlohmann/json.hpp>`. Defining it after the include has no
-    effect.
-
-    Enabling it also changes how a `char` array (including a string literal, e.g. `json::parse("123")`) is read: such
-    an array normally carries a trailing `'\0'` contributed by the compiler, not by the source text. With this macro
-    enabled, that one trailing byte is trimmed if present so that parsing a string literal keeps working; every other
-    byte in the array - including any `'\0'` that is not the very last element - is read as real data and rejected
-    like any other unexpected byte. Arrays of any other element type (`unsigned char`, `std::uint8_t`, ...), as used
-    for CBOR or MessagePack, are never affected by this trimming; their full extent - including a genuine trailing
-    `0x00` - is always preserved, in both states of this macro.
-
-!!! tip "Workaround without the macro"
-
-    To reject a NUL byte without enabling this macro, trim your input yourself before calling `parse()`:
-
-    ```cpp
-    s.resize(s.find('\0')); // drop everything from the first NUL onward, if any
-    json::parse(s);
-    ```
-
-## Examples
-
-??? example "Default behavior (macro not defined)"
-
-    Without the macro, a NUL byte silently ends parsing at that point:
-
-    ```cpp
-    #include <nlohmann/json.hpp>
-
-    using json = nlohmann::json;
-
-    int main()
-    {
-        json j = json::parse(std::string("123") + '\0' + "true");
-        // j is 123 -- the '\0' and everything after it is silently ignored
-    }
-    ```
-
-??? example "Opt-in strict handling (macro defined to 1)"
-
-    With the macro, a NUL byte is rejected like any other unexpected byte:
-
-    ```cpp
-    #define JSON_STRICT_NUL_HANDLING 1
-    #include <nlohmann/json.hpp>
-
-    using json = nlohmann::json;
-
-    int main()
-    {
-        json j = json::parse(std::string("123") + '\0' + "true");
-        // throws parse_error.101 -- the NUL byte is now invalid input,
-        // exactly like any other unexpected trailing byte
-
-        json ok = json::parse("123");
-        // ok is 123 -- parsing from a string literal still works
-    }
-    ```
-
-## See also
-
- [FAQ: NUL bytes in the input](../../home/faq.md#nul-bytes-in-the-input)
- [**parse**](../basic_json/parse.md) - deserialize from a compatible input
- [**accept**](../basic_json/accept.md) - check if the input is valid JSON
- [**operator>>**](../operator_gtgt.md) - deserialize from stream
-
-## Version history
-
- Added in version 3.13.0.
- Planned to become the default (with the macro removed) in version 4.0.0.
@@ -12,11 +12,9 @@
 Controls how exceptions are handled by the library.

 1. This macro overrides [`#!cpp catch`](https://en.cppreference.com/w/cpp/language/try_catch) calls inside the library.
-   The argument is the type of the exception to catch. The library uses it in a single place: to swallow any exception
-   escaping the parent-pointer check that [`JSON_DIAGNOSTICS`](json_diagnostics.md) adds to the class invariant. The
-   places where the library catches its own [`json::out_of_range`](../../home/exceptions.md#out-of-range) exceptions
-   use `JSON_INTERNAL_CATCH` instead, which `JSON_CATCH_USER` also overrides unless `JSON_INTERNAL_CATCH_USER` is
-   defined. The macro is always followed by a scope.
+   The argument is the type of the exception to catch. As of version 3.8.0, the library only catches `std::out_of_range`
+   exceptions internally to rethrow them as [`json::out_of_range`](../../home/exceptions.md#out-of-range) exceptions.
+   The macro is always followed by a scope.
 2. This macro overrides `#!cpp throw` calls inside the library. The argument is the exception to be thrown. Note that
   `JSON_THROW_USER` should leave the current scope (e.g., by throwing or aborting), as continuing after it may yield
   undefined behavior.
@@ -24,14 +24,6 @@ By default, implicit conversions are enabled.
    You can prepare existing code by already defining `JSON_USE_IMPLICIT_CONVERSIONS` to `0` and replace any implicit
    conversions with calls to [`get`](../basic_json/get.md).

-!!! tip "Automatic migration"
-
-    The community-maintained clang-tidy check `modernize-nlohmann-json-explicit-conversions` rewrites implicit
-    conversions into explicit calls to [`get`](../basic_json/get.md); for example, `#!cpp int i = j;` becomes
-    `#!cpp int i = j.get<int>();`. The check is not part of clang-tidy itself, and it does not catch every case (for
-    example, constructing a `std::optional` from a JSON value), so review the result. See
-    [discussion #4610](https://github.com/nlohmann/json/discussions/4610) for how to build and use it.
-
 !!! hint "CMake option"

    Implicit conversions can also be controlled with the CMake option
@@ -1,71 +0,0 @@
-# JSON_USE_SIMDUTF
-
-```cpp
-#define JSON_USE_SIMDUTF
-```
-
-When defined, the parser validates the UTF-8 content of JSON strings that come from a **contiguous byte input**
-(`std::string`, `std::vector<char>`/`<std::uint8_t>`, string literals, `const char*` ranges, …) using the
-[simdutf](https://github.com/simdutf/simdutf) library instead of the built-in scalar validator. On text with many
-non-ASCII characters (e.g. CJK or emoji) this can validate several times faster.
-
-This is an **opt-in external dependency**. The library itself remains header-only and its behavior is unchanged: the
-same input is accepted or rejected either way, and every parse error is reported at the same position with the same
-message (simdutf is only used to fast-path *valid* runs; anything it flags falls back to the scalar path so the exact
-diagnostic is preserved). Streaming inputs (files, `std::istream`, wide strings, user-defined adapters) always use the
-scalar path.
-
-When `JSON_USE_SIMDUTF` is defined you must make the `simdutf.h` header available on the include path and link the
-simdutf library. When it is not defined, no simdutf header is included and there is no dependency.
-
-!!! note "Requires C++17"
-
-    simdutf requires C++17 and its header rejects older standards with an `#!cpp #error`. The backend is therefore only
-    compiled in from C++17 on. In C++11 and C++14 the macro has no effect and the scalar validator is used, which
-    accepts and rejects exactly the same input -- only throughput differs. Setting the macro project-wide is therefore
-    safe even when some translation units are built with an older standard.
-
-!!! warning "Define consistently"
-
-    The macro selects between two definitions of the same inline validation function. It must therefore be defined
-    identically for **every** translation unit that includes the library; mixing translation units that define it with
-    ones that do not is an ODR violation. Prefer setting it as a compile definition on the target rather than with
-    `#!cpp #define` in individual source files.
-
-## Default definition
-
-By default, `#!cpp JSON_USE_SIMDUTF` is not defined and the portable C++11 scalar validator is used.
-
-```cpp
-#undef JSON_USE_SIMDUTF
-```
-
-## Examples
-
-??? example
-
-    The code below enables the simdutf backend for UTF-8 validation.
-
-    ```cpp
-    #define JSON_USE_SIMDUTF 1
-    #include <nlohmann/json.hpp>
-
-    ...
-    ```
-
-    The project must also link against simdutf, e.g. with CMake:
-
-    ```cmake
-    target_compile_definitions(your_target PRIVATE JSON_USE_SIMDUTF)
-    target_link_libraries(your_target PRIVATE simdutf::simdutf)
-    ```
-
-!!! hint "Testing this configuration"
-
-    The unit tests can be built against the simdutf backend with the CMake option `JSON_TestSimdutf` (`OFF` by
-    default), which fetches simdutf and defines `JSON_USE_SIMDUTF` for every test target. The `ci_test_simdutf` target
-    runs the whole test suite in that configuration.
-
-## Version history
-
- Added in version 3.13.0.
@@ -57,7 +57,8 @@ Summary:
 :   name of the base type (class, struct) `type` is derived from

 `member` (in)
-:   name of the member variable to serialize/deserialize; up to 63 members can be given as a comma-separated list
+:   name of the member variable to serialize/deserialize; up to 63 members can be given as a comma-separated
+    list, which may also be empty

 ## Default definition

@@ -127,6 +128,20 @@ void to_json(BasicJsonType& j, const B& b) {
    - Macros 4, 5, and 6 have the same prerequisites of [NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE](nlohmann_define_type_non_intrusive.md).
    - Serialization/deserialization of base types must be defined.

+!!! info "Derived types without own members"
+
+    The member list may be empty. The macro then generates a `to_json`/`from_json` pair that only delegates to
+    the base type, so `type` serializes exactly like `base_type`:
+
+    ```cpp
+    struct derived : base
+    {
+        NLOHMANN_DEFINE_DERIVED_TYPE_INTRUSIVE(derived, base)
+    };
+    ```
+
+    The `WITH_NAMES` variants do not support this.
+
 !!! warning "Implementation limits"

    See Implementation limits for [NLOHMANN_DEFINE_TYPE_INTRUSIVE](nlohmann_define_type_intrusive.md) and
@@ -33,7 +33,8 @@ Summary:
 :   name of the type (class, struct) to serialize/deserialize

 `member` (in)
-:   name of the member variable to serialize/deserialize; up to 63 members can be given as a comma-separated list
+:   name of the member variable to serialize/deserialize; up to 63 members can be given as a comma-separated
+    list, which may also be empty

 ## Default definition

@@ -58,6 +59,20 @@ See the examples below for the concrete generated code.

 [GetNonDefNonCopy]: ../../features/arbitrary_types.md#how-can-i-use-get-for-non-default-constructiblenon-copyable-types

+!!! info "Types without members"
+
+    The member list may be empty. The macro then generates a `to_json` that produces an empty JSON object
+    `#!json {}`, and a `from_json` that reads no members:
+
+    ```cpp
+    struct marker
+    {
+        NLOHMANN_DEFINE_TYPE_INTRUSIVE(marker)
+    };
+    ```
+
+    The `WITH_NAMES` variants do not support this.
+
 !!! warning "Implementation limits"

    - The current implementation is limited to at most 63 member variables. If you want to serialize/deserialize types
@@ -33,7 +33,8 @@ Summary:
 :   name of the type (class, struct) to serialize/deserialize

 `member` (in)
-:   name of the (public) member variable to serialize/deserialize; up to 63 members can be given as a comma-separated list
+:   name of the (public) member variable to serialize/deserialize; up to 63 members can be given as a
+    comma-separated list, which may also be empty

 ## Default definition

@@ -59,6 +60,18 @@ See the examples below for the concrete generated code.

 [GetNonDefNonCopy]: ../../features/arbitrary_types.md#how-can-i-use-get-for-non-default-constructiblenon-copyable-types

+!!! info "Types without members"
+
+    The member list may be empty. The macro then generates a `to_json` that produces an empty JSON object
+    `#!json {}`, and a `from_json` that reads no members:
+
+    ```cpp
+    struct marker {};
+    NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(marker)
+    ```
+
+    The `WITH_NAMES` variants do not support this.
+
 !!! warning "Implementation limits"

    - The current implementation is limited to at most 63 member variables. If you want to serialize/deserialize types
@@ -33,53 +33,17 @@ A UTF-8 byte order mark is silently ignored.
 Invalid Unicode escapes and unpaired surrogates in the input are reported as
 [`parse_error.101`](../home/exceptions.md#jsonexceptionparse_error101) with a detailed message.

-`operator>>` parses exactly one JSON value, so it can be called repeatedly to read a sequence of concatenated JSON
-values from the same stream:
+`operator>>` parses exactly one JSON value and leaves the stream positioned right after it, so it can be called
+repeatedly to read a sequence of concatenated JSON values from the same stream:

 ```cpp
 json j1, j2;
-input >> j1;  // parses the first value
+input >> j1;  // parses the first value, stream now positioned right after it
 input >> j2;  // parses the next value
 ```

-!!! warning "A number must be followed by whitespace"
-
-    A number is only terminated by the character that follows it. That character is read from the stream to detect the
-    end of the number, and it is **not** put back. When a value that is a number is immediately followed by the next
-    value, the first character of that next value is lost:
-
-    ```cpp
-    std::istringstream input("1true");
-    json j1, j2;
-    input >> j1;  // j1 == 1
-    input >> j2;  // throws parse_error.101: the stream now starts at "rue"
-    ```
-
-    Separating the values with whitespace avoids this, because the character that is eaten is then the separator:
-
-    ```cpp
-    std::istringstream input("1 true");
-    json j1, j2;
-    input >> j1;  // j1 == 1
-    input >> j2;  // j2 == true
-    ```
-
-    Only numbers are affected. Values ending in a self-delimiting character do not read past themselves, so
-    `truefalse`, `[1][2]`, `{"a":1}{"b":2}`, and `"a""b"` can be read back to back without a separator.
-
-    Define [`JSON_PRECISE_STREAM_POSITION`](macros/json_precise_stream_position.md) to `1` to leave the terminating character in the stream
-    instead, so that the stream is positioned right after the value for every value type and no separator is
-    needed. This is tracked in [#5340](https://github.com/nlohmann/json/issues/5340).
-
-Note that reading concatenated values does **not** work for [JSON Lines](../features/parsing/json_lines.md)
-(newline-delimited JSON) input -- see that page for why and for the recommended alternative.
-
-By default, a `'\0'` (NUL) byte encountered while reading a value is treated as end of input, rather than as an
-ordinary (and, outside of a string, invalid) byte; see the [FAQ entry](../home/faq.md#nul-bytes-in-the-input) for
-details and the [`JSON_STRICT_NUL_HANDLING`](macros/json_strict_nul_handling.md) macro to opt into rejecting it
-instead. Because `operator>>` only parses a single value and does not require the rest of the stream to be consumed,
-a NUL byte *after* a complete value has no effect on `operator>>` either way; it only matters while a value is still
-being read.
+Note this does **not** work for [JSON Lines](../features/parsing/json_lines.md) (newline-delimited JSON) input --
+see that page for why and for the recommended alternative.

 !!! warning "Deprecation"

@@ -107,14 +71,7 @@ being read.

 - [accept](basic_json/accept.md) - check if the input is valid JSON
 - [parse](basic_json/parse.md) - deserialize from a compatible input
- [`JSON_STRICT_NUL_HANDLING`](macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
-  instead of treating it as end of input
- [`JSON_PRECISE_STREAM_POSITION`](macros/json_precise_stream_position.md) - opt in to leaving the stream positioned right after a number

 ## Version history

 - Added in version 1.0.0.
- `JSON_STRICT_NUL_HANDLING` added in version 3.13.0 to optionally reject a NUL byte in the input instead of treating
-  it as end of input; planned to become the default in version 4.0.0.
- `JSON_PRECISE_STREAM_POSITION` added in version 3.13.0 to optionally leave the character that terminates a number in
-  the stream; planned to become the default in version 4.0.0.
@@ -13,12 +13,6 @@ Therefore, adding object elements can yield a reallocation in which case all ite
 [`end()`](basic_json/end.md) iterator) and all references to the elements are invalidated. Also, any iterator or
 reference after the insertion point will point to the same index, which is now a different value.

-## Complexity
-
-[`ordered_map`](ordered_map.md) has no lookup index: every key-based object operation is a linear scan, so building or
-parsing an object of `n` keys costs O(n²) rather than O(n log n). See
-[`ordered_map` complexity](ordered_map.md#complexity) for the per-operation table and for measured numbers.
-
 ## Examples

 ??? example
@@ -56,48 +56,6 @@ std::equal_to<>     // since C++14
 - **find**
 - **insert**

-## Complexity
-
-Because the elements are stored in a `std::vector` in insertion order, there is no index to look a key up by. Every
-key-based operation performs a **linear scan** over the stored elements. With `n` denoting the number of elements in the
-container:
-
-| Operation                              | Complexity     | Note                                                     |
-|----------------------------------------|----------------|----------------------------------------------------------|
-| **emplace**                            | O(n)           | scans for an existing key, then appends (amortized O(1)) |
-| **operator\[\]**                       | O(n)           | delegates to **emplace** (non-const) or **at** (const)   |
-| **at**                                 | O(n)           | throws `#!cpp std::out_of_range` if the key is not found |
-| **find**                               | O(n)           |                                                          |
-| **count**                              | O(n)           | the result is always 0 or 1                              |
-| **erase(key)**                         | O(n)           | scan, then move the remaining elements one position down |
-| **erase(pos)**, **erase(first, last)** | O(n)           | moves all elements after the erased range                |
-| **insert(value)**                      | O(n)           | equivalent to **emplace**                                |
-| **insert(first, last)**                | O((n + m) * m) | for `m` inserted elements                                |
-
-This differs from `#!cpp std::map`, where the same operations are O(log n).
-
-!!! warning "Quadratic cost of building large objects"
-
-    Because every insertion scans all elements inserted so far, building an object of `n` distinct keys costs
-    **O(n²)** in total. This applies to filling an [`ordered_json`](ordered_json.md) object key by key as well as to
-    parsing one, since the parser inserts each key as it is read.
-
-    The cost is negligible for the object sizes typically found in configuration files or API payloads, but it grows
-    steeply for machine-generated objects with many thousands of keys. Measured with `-O2 -DNDEBUG` for parsing a flat
-    object of `n` keys, relative to `#!cpp nlohmann::json` (which uses `#!cpp std::map`):
-
-    | `n`    | `json` | `ordered_json` | factor |
-    |--------|--------|----------------|--------|
-    | 2000   | 0.7 ms | 3.6 ms         | 5×     |
-    | 4000   | 0.8 ms | 14.0 ms        | 19×    |
-    | 8000   | 1.6 ms | 67.8 ms        | 43×    |
-    | 16 000 | 3.3 ms | 181.6 ms       | 54×    |
-
-    If key order matters for objects of that size, consider a container with a lookup index, such as
-    [`tsl::ordered_map`](https://github.com/Tessil/ordered-map)
-    ([integration](https://github.com/nlohmann/json/issues/546#issuecomment-304447518)), as the object type -- see
-    [object order](../features/object_order.md).
-
 ## Examples

 ??? example
@@ -1,70 +0,0 @@
-# Assurance case
-
-This page argues why the library meets its security requirements. It describes the threats the library faces, where the
-trust boundaries lie, and how the library's design and the [quality assurance](quality_assurance.md) counter these
-threats. To report a vulnerability, see the [security policy](security_policy.md).
-
-## Threat model
-
-The library parses, stores, and serializes JSON values in memory. It does not open network connections, does not open
-files (it only reads from streams or `std::FILE*` handles that the caller has already opened), does not read environment
-variables, and does not implement cryptography or handle credentials.
-
-The primary threat is therefore **untrusted input**: JSON text or binary data (BJData, BSON, CBOR, MessagePack, UBJSON)
-that an attacker controls, passed to [`parse`](../api/basic_json/parse.md), [`accept`](../api/basic_json/accept.md),
-[`sax_parse`](../api/basic_json/sax_parse.md), or one of the `from_*` functions such as
-[`from_cbor`](../api/basic_json/from_cbor.md). Such input may try to
-
- make the library read or write out of bounds (malformed lengths, truncated input, invalid UTF-8),
- trigger undefined behavior (integer overflow in sizes or numbers, invalid casts),
- exhaust memory (huge announced sizes), or
- exhaust the call stack (deeply nested arrays and objects).
-
-## Trust boundaries
-
- **Untrusted:** all serialized input read by the parser, the SAX interface, and the binary readers. The library must
-  handle every possible input by either producing a value or throwing a [`parse_error`](../home/exceptions.md#parse-errors)
-  (or returning `false` when exceptions are disabled for the call).
- **Trusted:** the C++ code that calls the library. Calling a function with violated preconditions, for instance
-  accessing an array with [`operator[]`](../api/basic_json/operator%5B%5D.md) out of range, is a programming error and
-  not a security boundary. Such preconditions are checked with [runtime assertions](../features/assertions.md) in debug
-  builds; functions such as [`at`](../api/basic_json/at.md) offer checked access with exceptions.
-
-## Secure design
-
- **Strict parsing.** The parser accepts exactly the JSON grammar of [RFC 8259](https://datatracker.ietf.org/doc/html/rfc8259).
-  Extensions such as [comments](../features/comments.md) and [trailing commas](../features/trailing_commas.md) must be
-  enabled explicitly. Invalid UTF-8 is rejected.
- **Errors are reported, not ignored.** Malformed input results in a [`parse_error`](../home/exceptions.md#parse-errors)
-  with the byte position of the error. Binary readers do not trust announced sizes: strings and binary values grow
-  only as bytes are actually read, arrays reserve at most a fixed number of elements up front, and sizes that no
-  container can hold are rejected.
- **Memory is owned by values.** Each `basic_json` value owns its content, and there is no manual memory management in
-  user code. The destructor does not recurse, so destroying a deeply nested value does not exhaust the stack.
- **Bounded recursion.** The JSON parser and the binary readers keep their state in explicit stacks instead of
-  recursing per nesting level. Operations that walk a value, such as [`dump`](../api/basic_json/dump.md), copying,
-  hashing, and [`merge_patch`](../api/basic_json/merge_patch.md), recurse only up to a fixed depth and continue with an
-  explicit stack below it. Some operations, such as comparison, [`diff`](../api/basic_json/diff.md),
-  [`flatten`](../api/basic_json/flatten.md), and the binary writers, still recurse once per nesting level; work on them
-  is in progress. Applications that process untrusted input can limit its nesting depth with a
-  [parser callback](../features/parsing/parser_callbacks.md).
- **Invariants are checked.** The class invariant (for instance, that the pointer for the stored type is never null) is
-  checked with runtime assertions throughout the test suite.
-
-## Common weaknesses
-
-The following table maps the relevant classes of the [Common Weakness Enumeration](https://cwe.mitre.org) to the
-measures that counter them. The measures are described in detail in [Quality assurance](quality_assurance.md).
-
-| Weakness                                                                  | Countermeasures                                                                                  |
-|---------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------|
-| Out-of-bounds read/write ([CWE-125](https://cwe.mitre.org/data/definitions/125.html), [CWE-787](https://cwe.mitre.org/data/definitions/787.html)) | bounds checks on all reads from the input; AddressSanitizer and Valgrind on the test suite; OSS-Fuzz      |
-| Integer overflow ([CWE-190](https://cwe.mitre.org/data/definitions/190.html)) | UndefinedBehaviorSanitizer with integer overflow detection; Clang-Tidy; Cppcheck                 |
-| Use after free, double free ([CWE-416](https://cwe.mitre.org/data/definitions/416.html), [CWE-415](https://cwe.mitre.org/data/definitions/415.html)) | ownership of all memory by values; AddressSanitizer and Valgrind; Clang Static Analyzer          |
-| Memory leaks ([CWE-401](https://cwe.mitre.org/data/definitions/401.html)) | Valgrind (Memcheck) on the test suite                                                            |
-| Uncontrolled recursion ([CWE-674](https://cwe.mitre.org/data/definitions/674.html)) | iterative parser, binary readers, and destructor; bounded recursion in value operations; tests with deeply nested inputs |
-| Uncontrolled resource consumption ([CWE-400](https://cwe.mitre.org/data/definitions/400.html)) | allocations based on announced sizes are capped; OSS-Fuzz with memory limits                     |
-| Undefined behavior in general ([CWE-758](https://cwe.mitre.org/data/definitions/758.html)) | UndefinedBehaviorSanitizer; runtime assertions; Clang-Tidy, Cppcheck, Clang Static Analyzer, Infer |
-
-In addition, every line of the library is covered by the unit tests, and all parsers are fuzz-tested around the clock
-by [OSS-Fuzz](https://github.com/google/oss-fuzz/tree/master/projects/json).
@@ -1,40 +0,0 @@
-# Ecosystem
-
-The projects below build on top of `nlohmann::json` rather than merely using it - schema validators, language
-bindings, format converters, and similar building blocks. The list is not exhaustive, and is curated rather than
-automatically generated. If you maintain or know of a project that belongs here,
-[please let me know](mailto:mail@nlohmann.me).
-
-For products, applications, and organizations that use the library, see [Customers](../home/customers.md) instead.
-
-## Schema validation
-
- [**json-schema-validator**](https://github.com/pboettch/json-schema-validator), a JSON Schema (draft 7) validator
-  with human-readable error messages
-
-## Serialization and reflection
-
- [**nlohmann_json_reflect**](https://github.com/1261385937/nlohmann_json_reflect), a reflection extension for
-  (de)serializing nested containers-in-structs-in-containers
-
-## Encodings
-
- [**base-encode-decode**](https://github.com/saxonnicholls/base-encode-decode), a header-only Base64/32/16/8/4/2
-  (and DNA/RNA) encoding library, with an adapter that serializes binary data through `nlohmann::json`
-
-## Language bindings and interop
-
- [**pybind11_json**](https://github.com/pybind/pybind11_json), a bidirectional type caster between
-  `nlohmann::json` and Python objects for [pybind11](https://github.com/pybind/pybind11) bindings
- [**nanobind_json**](https://github.com/ianhbell/nanobind_json), the same idea for
-  [nanobind](https://github.com/wjakob/nanobind) bindings
- [**nlohmann_json_qt**](https://github.com/dpurgin/nlohmann_json_qt), deserialization helpers for Qt types
-  (`QString`, `QUrl`, `QDateTime`, `QVector`, ...) from `nlohmann::json`
- [**vulkan2json**](https://github.com/Fadis/vulkan2json), serialization and deserialization of Vulkan API structs
-
-## Format converters
-
- [**tojson**](https://github.com/mircodz/tojson), a header-only converter between YAML/XML documents and
-  `nlohmann::json`
- [**json2xml**](https://github.com/testillano/json2xml), a header-only converter from `nlohmann::json` to XML for
-  simple configuration documents
@@ -1,10 +1,7 @@
 # Community

- [Ecosystem](ecosystem.md) - third-party projects built on top of this library
 - [Code of Conduct](code_of_conduct.md) - the rules and norms of this project
 - [Contribution Guidelines](contribution_guidelines.md) - guidelines how to contribute to this project
 - [Governance](governance.md) - the governance model of this project
 - [Quality Assurance](quality_assurance.md) - how the quality of this project is assured
- [Roadmap](roadmap.md) - what the project will and will not do
 - [Security Policy](security_policy.md) - the security policy of the project
- [Assurance Case](assurance_case.md) - why the library meets its security requirements
@@ -66,7 +66,6 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
        | Clang 20.1.1                                 | x86_64       | Ubuntu 22.04.1 LTS                | GitHub    |
        | Clang 20.1.8 with GNU-like command-line      | x86_64       | Windows Server 2022 (Build 20348) | GitHub    |
        | Clang 21.1.8                                 | x86_64       | Ubuntu 22.04.1 LTS                | GitHub    |
-        | Clang 22.1.8                                 | x86_64       | Ubuntu 22.04.1 LTS                | GitHub    |
        | CUDA 11.8.0 (nvcc)                           | x86_64       | Ubuntu 22.04 LTS                  | GitHub    |
        | CUDA 12.1.1 (nvcc)                           | x86_64       | Ubuntu 22.04 LTS                  | GitHub    |
        | CUDA 12.6.3 (nvcc)                           | x86_64       | Ubuntu 22.04 LTS                  | GitHub    |
@@ -164,9 +163,6 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
 - [x] The parser is tested against extensive correctness suites for JSON compliance.
 - [x] In addition, the library is continuously fuzz-tested at [OSS-Fuzz](https://google.github.io/oss-fuzz/) where the
  library is checked against billions of inputs.
- [x] Every crash reported by OSS-Fuzz is fixed together with a unit test that reproduces it, and the fix references
-  the OSS-Fuzz issue. The round-trip checks of the fuzzer drivers are also part of the unit tests. See the
-  [fuzz testing documentation](https://github.com/nlohmann/json/blob/develop/tests/fuzzing.md#handling-oss-fuzz-reports).

 ## Static analysis

@@ -1,43 +0,0 @@
-# Roadmap
-
-This page describes what the project intends to do, and what it does not intend to do, over the next year. Concrete
-work items are tracked in the [GitHub milestones](https://github.com/nlohmann/json/milestones) and the
-[issue tracker](https://github.com/nlohmann/json/issues).
-
-## What the project will do
-
- **Keep the C++11 baseline.** The library will continue to compile with every
-  [supported C++11 compiler](https://github.com/nlohmann/json/blob/develop/README.md#supported-compilers). Features of
-  later standards are only used when they are guarded by the `JSON_HAS_CPP_*` macros.
- **Stay conformant to JSON.** The parser and serializer follow [RFC 8259](https://datatracker.ietf.org/doc/html/rfc8259).
-  Extensions such as [comments](../features/comments.md) or [trailing commas](../features/trailing_commas.md) remain
-  opt-in.
- **Keep the 3.x public API stable.** Releases follow [semantic versioning](https://semver.org). Changes that would
-  break existing code are only added behind a feature macro, so users can opt in and test their code before a next
-  major release.
- **Support a broad range of compilers and platforms.** The [CI](quality_assurance.md) keeps testing old and new
-  versions of GCC, Clang, MSVC, and other compilers on Linux, macOS, and Windows.
- **Keep the quality assurance up.** Every change keeps the test coverage at 100%, passes the static and dynamic
-  analysis, and is fuzz-tested by OSS-Fuzz, see [Quality assurance](quality_assurance.md).
- **Harden the library against hostile input.** Handling deeply nested values without exhausting the call stack is
-  ongoing work.
- **Fix bugs and security issues** reported through the issue tracker and the [security policy](security_policy.md).
-
-## What the project will not do
-
- **Break the public API of version 3.x.** See the
-  [contribution guidelines](https://github.com/nlohmann/json/blob/develop/.github/CONTRIBUTING.md#break-the-public-api)
-  for what counts as a breaking change.
- **Require a newer C++ standard than C++11.**
- **Break JSON conformance** or enable non-standard extensions by default.
- **Add dependencies** or require a build step. The library remains header-only, and the single header
-  `json.hpp` remains a complete distribution.
- **Trade simplicity for speed or memory efficiency.** Performance improvements are welcome, but the library is not
-  meant to compete with the fastest JSON libraries, see [Design goals](../home/design_goals.md).
-
-## Version 4.0
-
-There is no decision yet on whether or when a version 4.0 with breaking changes will be released. Proposals that need
-a major version, for instance stricter type conversions, are collected in issue
-[#3453](https://github.com/nlohmann/json/issues/3453). Until then, such changes are only added as opt-in behavior
-behind feature macros.
@@ -1,19 +0,0 @@
-#include <iostream>
-#include <map>
-
-#include <nlohmann/json.hpp>
-
-#include "custom_array_type.hpp"
-
-using custom_json = nlohmann::basic_json<std::map, custom_array_type>;
-
-int main()
-{
-    custom_json j = custom_json::array();
-    j.push_back(1);
-    j.push_back(2);
-    j.push_back(3);
-
-    std::cout << j.dump() << std::endl;
-    std::cout << std::boolalpha << (custom_json::parse(j.dump()) == j) << std::endl;
-}
@@ -1,152 +0,0 @@
-#pragma once
-
-#include <memory>
-#include <utility>
-#include <vector>
-
-// A minimal, self-contained ArrayType built around a private std::vector.
-// See https://json.nlohmann.me/features/types/template_parameters/#arraytype
-template<class T, class Allocator = std::allocator<T>>
-class custom_array_type
-{
-    using vector_t = std::vector<T, Allocator>;
-    vector_t data_;
-
-  public:
-    using value_type = typename vector_t::value_type;
-    using size_type = typename vector_t::size_type;
-    using iterator = typename vector_t::iterator;
-    using const_iterator = typename vector_t::const_iterator;
-
-    custom_array_type() = default;
-    custom_array_type(const custom_array_type&) = default;
-    custom_array_type(custom_array_type&&) = default;
-    custom_array_type& operator=(const custom_array_type&) = default;
-    custom_array_type& operator=(custom_array_type&&) = default;
-
-    template<class InputIt>
-    custom_array_type(InputIt first, InputIt last) : data_(first, last) {}
-
-    custom_array_type(size_type count, const T& value) : data_(count, value) {}
-
-    iterator begin()
-    {
-        return data_.begin();
-    }
-    iterator end()
-    {
-        return data_.end();
-    }
-    const_iterator begin() const
-    {
-        return data_.begin();
-    }
-    const_iterator end() const
-    {
-        return data_.end();
-    }
-    const_iterator cbegin() const
-    {
-        return data_.cbegin();
-    }
-    const_iterator cend() const
-    {
-        return data_.cend();
-    }
-
-    bool empty() const
-    {
-        return data_.empty();
-    }
-    size_type size() const
-    {
-        return data_.size();
-    }
-    size_type max_size() const
-    {
-        return data_.max_size();
-    }
-    void clear()
-    {
-        data_.clear();
-    }
-    void resize(size_type n)
-    {
-        data_.resize(n);
-    }
-
-    T& operator[](size_type pos)
-    {
-        return data_[pos];
-    }
-    const T& operator[](size_type pos) const
-    {
-        return data_[pos];
-    }
-
-    T& back()
-    {
-        return data_.back();
-    }
-    const T& back() const
-    {
-        return data_.back();
-    }
-
-    void push_back(const T& value)
-    {
-        data_.push_back(value);
-    }
-    void push_back(T&& value)
-    {
-        data_.push_back(std::move(value));
-    }
-
-    template<class... Args>
-    void emplace_back(Args&& ... args)
-    {
-        data_.emplace_back(std::forward<Args>(args)...);
-    }
-
-    void pop_back()
-    {
-        data_.pop_back();
-    }
-
-    iterator insert(const_iterator pos, const T& value)
-    {
-        return data_.insert(pos, value);
-    }
-    iterator insert(const_iterator pos, size_type count, const T& value)
-    {
-        return data_.insert(pos, count, value);
-    }
-    template<class InputIt>
-    iterator insert(const_iterator pos, InputIt first, InputIt last)
-    {
-        return data_.insert(pos, first, last);
-    }
-
-    iterator erase(const_iterator pos)
-    {
-        return data_.erase(pos);
-    }
-    iterator erase(const_iterator first, const_iterator last)
-    {
-        return data_.erase(first, last);
-    }
-
-    void swap(custom_array_type& other)
-    {
-        data_.swap(other.data_);
-    }
-
-    friend bool operator==(const custom_array_type& lhs, const custom_array_type& rhs)
-    {
-        return lhs.data_ == rhs.data_;
-    }
-    friend bool operator<(const custom_array_type& lhs, const custom_array_type& rhs)
-    {
-        return lhs.data_ < rhs.data_;
-    }
-};
@@ -1,2 +0,0 @@
-[1,2,3]
-true
@@ -1,21 +0,0 @@
-#include <cstdint>
-#include <iostream>
-#include <map>
-#include <string>
-#include <vector>
-
-#include <nlohmann/json.hpp>
-
-#include "custom_binary_type.hpp"
-
-using custom_json = nlohmann::basic_json<std::map, std::vector, std::string, bool,
-      std::int64_t, std::uint64_t, double, std::allocator,
-      nlohmann::adl_serializer, custom_binary_type>;
-
-int main()
-{
-    const auto j = custom_json::binary({0x01, 0x02, 0x03});
-
-    std::cout << j.dump() << std::endl;
-    std::cout << std::boolalpha << (custom_json::from_cbor(custom_json::to_cbor(j)) == j) << std::endl;
-}
@@ -1,112 +0,0 @@
-#pragma once
-
-#include <cstdint>
-#include <initializer_list>
-#include <vector>
-
-// A minimal, self-contained BinaryType built around a private std::vector.
-// See https://json.nlohmann.me/features/types/template_parameters/#binarytype
-class custom_binary_type
-{
-    using vector_t = std::vector<std::uint8_t>;
-    vector_t data_;
-
-  public:
-    using value_type = vector_t::value_type;
-    using size_type = vector_t::size_type;
-    using iterator = vector_t::iterator;
-    using const_iterator = vector_t::const_iterator;
-
-    custom_binary_type() = default;
-    custom_binary_type(const custom_binary_type&) = default;
-    custom_binary_type(custom_binary_type&&) = default;
-    custom_binary_type& operator=(const custom_binary_type&) = default;
-    custom_binary_type& operator=(custom_binary_type&&) = default;
-
-    template<class InputIt>
-    custom_binary_type(InputIt first, InputIt last) : data_(first, last) {}
-
-    // so basic_json::binary({0x01, 0x02}) can build one directly
-    custom_binary_type(std::initializer_list<std::uint8_t> init) : data_(init) {}
-
-    size_type size() const
-    {
-        return data_.size();
-    }
-    bool empty() const
-    {
-        return data_.empty();
-    }
-    void clear()
-    {
-        data_.clear();
-    }
-    void resize(size_type n)
-    {
-        data_.resize(n);
-    }
-
-    // read-only is enough: the writers only ever read from a binary value
-    const std::uint8_t* data() const
-    {
-        return data_.data();
-    }
-
-    std::uint8_t& operator[](size_type pos)
-    {
-        return data_[pos];
-    }
-    std::uint8_t operator[](size_type pos) const
-    {
-        return data_[pos];
-    }
-
-    std::uint8_t& back()
-    {
-        return data_.back();
-    }
-    std::uint8_t back() const
-    {
-        return data_.back();
-    }
-
-    iterator begin()
-    {
-        return data_.begin();
-    }
-    iterator end()
-    {
-        return data_.end();
-    }
-    const_iterator begin() const
-    {
-        return data_.begin();
-    }
-    const_iterator end() const
-    {
-        return data_.end();
-    }
-    const_iterator cbegin() const
-    {
-        return data_.cbegin();
-    }
-    const_iterator cend() const
-    {
-        return data_.cend();
-    }
-
-    template<class InputIt>
-    iterator insert(const_iterator pos, InputIt first, InputIt last)
-    {
-        return data_.insert(pos, first, last);
-    }
-
-    friend bool operator==(const custom_binary_type& lhs, const custom_binary_type& rhs)
-    {
-        return lhs.data_ == rhs.data_;
-    }
-    friend bool operator<(const custom_binary_type& lhs, const custom_binary_type& rhs)
-    {
-        return lhs.data_ < rhs.data_;
-    }
-};
@@ -1,2 +0,0 @@
-{"bytes":[1,2,3],"subtype":null}
-true
@@ -1,26 +0,0 @@
-#include <iostream>
-#include <type_traits>
-#include <vector>
-
-#include <nlohmann/json.hpp>
-
-#include "custom_object_type.hpp"
-
-using custom_json = nlohmann::basic_json<custom_object_type, std::vector>;
-
-int main()
-{
-    custom_json j;
-    j["pi"] = 3.141;
-    j["happy"] = true;
-    j["list"] = {1, 2, 3};
-
-    std::cout << j.dump(2) << std::endl;
-    std::cout << std::boolalpha << (custom_json::parse(j.dump()) == j) << std::endl;
-
-    // custom_object_type has no key_compare member, so object_comparator_t
-    // falls back to its default
-    std::cout << std::boolalpha
-              << std::is_same<custom_json::object_comparator_t, custom_json::default_object_comparator_t>::value
-              << std::endl;
-}
@@ -1,144 +0,0 @@
-#pragma once
-
-#include <map>
-#include <utility>
-
-// A minimal, self-contained ObjectType built around a private std::map.
-// key_compare is deliberately not exposed: when an ObjectType has no
-// key_compare member, the library falls back to its own default comparator.
-// See https://json.nlohmann.me/features/types/template_parameters/#objecttype
-template<class Key, class T, class Compare, class Allocator>
-class custom_object_type
-{
-    using map_t = std::map<Key, T, Compare, Allocator>;
-    map_t data_;
-
-  public:
-    using key_type = typename map_t::key_type;
-    using mapped_type = typename map_t::mapped_type;
-    using value_type = typename map_t::value_type;
-    using size_type = typename map_t::size_type;
-    using iterator = typename map_t::iterator;
-    using const_iterator = typename map_t::const_iterator;
-
-    custom_object_type() = default;
-    custom_object_type(const custom_object_type&) = default;
-    custom_object_type(custom_object_type&&) = default;
-    custom_object_type& operator=(const custom_object_type&) = default;
-    custom_object_type& operator=(custom_object_type&&) = default;
-
-    template<class InputIt>
-    custom_object_type(InputIt first, InputIt last) : data_(first, last) {}
-
-    iterator begin()
-    {
-        return data_.begin();
-    }
-    iterator end()
-    {
-        return data_.end();
-    }
-    const_iterator begin() const
-    {
-        return data_.begin();
-    }
-    const_iterator end() const
-    {
-        return data_.end();
-    }
-    const_iterator cbegin() const
-    {
-        return data_.cbegin();
-    }
-    const_iterator cend() const
-    {
-        return data_.cend();
-    }
-
-    bool empty() const
-    {
-        return data_.empty();
-    }
-    size_type size() const
-    {
-        return data_.size();
-    }
-    size_type max_size() const
-    {
-        return data_.max_size();
-    }
-    void clear()
-    {
-        data_.clear();
-    }
-
-    iterator find(const key_type& key)
-    {
-        return data_.find(key);
-    }
-    const_iterator find(const key_type& key) const
-    {
-        return data_.find(key);
-    }
-    size_type count(const key_type& key) const
-    {
-        return data_.count(key);
-    }
-
-    std::pair<iterator, bool> emplace(const key_type& key, const mapped_type& value)
-    {
-        return data_.emplace(key, value);
-    }
-
-    std::pair<iterator, bool> insert(const value_type& value)
-    {
-        return data_.insert(value);
-    }
-
-    template<class InputIt>
-    void insert(InputIt first, InputIt last)
-    {
-        data_.insert(first, last);
-    }
-
-    mapped_type& operator[](const key_type& key)
-    {
-        return data_[key];
-    }
-
-    mapped_type& at(const key_type& key)
-    {
-        return data_.at(key);
-    }
-    const mapped_type& at(const key_type& key) const
-    {
-        return data_.at(key);
-    }
-
-    iterator erase(iterator pos)
-    {
-        return data_.erase(pos);
-    }
-    iterator erase(iterator first, iterator last)
-    {
-        return data_.erase(first, last);
-    }
-    size_type erase(const key_type& key)
-    {
-        return data_.erase(key);
-    }
-
-    void swap(custom_object_type& other)
-    {
-        data_.swap(other.data_);
-    }
-
-    friend bool operator==(const custom_object_type& lhs, const custom_object_type& rhs)
-    {
-        return lhs.data_ == rhs.data_;
-    }
-    friend bool operator<(const custom_object_type& lhs, const custom_object_type& rhs)
-    {
-        return lhs.data_ < rhs.data_;
-    }
-};
@@ -1,11 +0,0 @@
-{
-  "happy": true,
-  "list": [
-    1,
-    2,
-    3
-  ],
-  "pi": 3.141
-}
-true
-true
@@ -1,20 +0,0 @@
-#include <iostream>
-#include <map>
-#include <vector>
-
-#include <nlohmann/json.hpp>
-
-#include "custom_string_type.hpp"
-
-using custom_json = nlohmann::basic_json<std::map, std::vector, custom_string_type>;
-
-int main()
-{
-    custom_json j;
-    j["pi"] = 3.141;
-    j["happy"] = true;
-    j["list"] = {1, 2, 3};
-
-    std::cout << j.dump(2) << std::endl;
-    std::cout << std::boolalpha << (custom_json::parse(j.dump()) == j) << std::endl;
-}
@@ -1,134 +0,0 @@
-#pragma once
-
-#include <ostream>
-#include <string>
-
-// A minimal, self-contained StringType built around a private std::string.
-// Wraps rather than inherits, so it exposes exactly what the library needs
-// and nothing more of std::string's interface.
-//
-// Covers the "Always required" members, the extras needed for the binary
-// formats, and the extras needed for JSON Pointer / flatten / unflatten /
-// diff. Extending it further (e.g. for std::hash<basic_json> or to_bson) is
-// a matter of adding the extra members listed in the "Required for other
-// functionality" table.
-//
-// See https://json.nlohmann.me/features/types/template_parameters/#stringtype
-class custom_string_type
-{
-    std::string data_;
-
-  public:
-    using value_type = char;
-    using size_type = std::string::size_type;
-    using iterator = std::string::iterator;
-    using const_iterator = std::string::const_iterator;
-
-    static constexpr size_type npos = std::string::npos;
-
-    custom_string_type() = default;
-    custom_string_type(const custom_string_type&) = default;
-    custom_string_type(custom_string_type&&) = default;
-    custom_string_type& operator=(const custom_string_type&) = default;
-    custom_string_type& operator=(custom_string_type&&) = default;
-
-    // not explicit: the library relies on being able to hand it a string literal
-    custom_string_type(const char* s) : data_(s) {}
-    custom_string_type(const char* s, size_type count) : data_(s, count) {}
-    custom_string_type(size_type count, char ch) : data_(count, ch) {}
-
-    size_type size() const
-    {
-        return data_.size();
-    }
-    bool empty() const
-    {
-        return data_.empty();
-    }
-    void clear()
-    {
-        data_.clear();
-    }
-    void resize(size_type n)
-    {
-        data_.resize(n);
-    }
-    void resize(size_type n, char c)
-    {
-        data_.resize(n, c);
-    }
-    void reserve(size_type n)
-    {
-        data_.reserve(n);
-    }
-
-    // must stay null-terminated -- the parser hands this to std::strtoull &
-    // friends; std::string::data() has guaranteed that since C++11
-    const char* data() const
-    {
-        return data_.data();
-    }
-
-    void push_back(char c)
-    {
-        data_.push_back(c);
-    }
-
-    char& operator[](size_type pos)
-    {
-        return data_[pos];
-    }
-    char operator[](size_type pos) const
-    {
-        return data_[pos];
-    }
-
-    custom_string_type& append(const char* s, size_type count)
-    {
-        data_.append(s, count);
-        return *this;
-    }
-    custom_string_type& append(const custom_string_type& other)
-    {
-        data_.append(other.data_);
-        return *this;
-    }
-
-    size_type find_first_of(char c, size_type pos = 0) const
-    {
-        return data_.find_first_of(c, pos);
-    }
-
-    iterator begin()
-    {
-        return data_.begin();
-    }
-    iterator end()
-    {
-        return data_.end();
-    }
-    const_iterator begin() const
-    {
-        return data_.begin();
-    }
-    const_iterator end() const
-    {
-        return data_.end();
-    }
-
-    friend bool operator==(const custom_string_type& lhs, const custom_string_type& rhs)
-    {
-        return lhs.data_ == rhs.data_;
-    }
-    friend bool operator<(const custom_string_type& lhs, const custom_string_type& rhs)
-    {
-        return lhs.data_ < rhs.data_;
-    }
-
-    // not required by the library itself, but dump() returns a custom_string_type
-    // and this makes `std::cout << j.dump()` work as expected
-    friend std::ostream& operator<<(std::ostream& os, const custom_string_type& s)
-    {
-        return os << s.data_;
-    }
-};
@@ -1,10 +0,0 @@
-{
-  "happy": true,
-  "list": [
-    1,
-    2,
-    3
-  ],
-  "pi": 3.141
-}
-true
@@ -4,8 +4,8 @@
 Hello, world!
 1 2 3 4 5 

+string: "Hello, world!"
 number: {"floating-point":17.23,"integer":42}
 null: null
-string: "Hello, world!"
 boolean: true
 array: [1,2,3,4,5]
@@ -4,8 +4,8 @@
 Hello, world!
 1 2 3 4 5 

+string: "Hello, world!"
 number: {"floating-point":17.23,"integer":42}
 null: null
-string: "Hello, world!"
 boolean: true
 array: [1,2,3,4,5]
@@ -4,9 +4,9 @@
 Hello, world!
 1 2 3 4 5 

+string: "Hello, world!"
 number: {"floating-point":17.23,"integer":42}
 null: null
-string: "Hello, world!"
 boolean: true
 array: [1,2,3,4,5]
 [json.exception.type_error.302] type must be boolean, but is string
@@ -1,47 +0,0 @@
-#include <iostream>
-#include <nlohmann/json.hpp>
-
-using json = nlohmann::json;
-
-int main()
-{
-    // a JSON text with an array and a number inside an object
-    auto text = R"({"IDs": [116, 943], "Width": 800})";
-
-    // discard the array when the parser reads its opening bracket
-    json j_array_start = json::parse(text, [](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
-    {
-        return event != json::parse_event_t::array_start;
-    });
-
-    // discard the same array when the parser reads its closing bracket
-    json j_array_end = json::parse(text, [](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
-    {
-        return event != json::parse_event_t::array_end;
-    });
-
-    // discard the number, but keep its key
-    json j_value = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & parsed)
-    {
-        return !(event == json::parse_event_t::value && parsed == json(800));
-    });
-
-    // discard the key of the number
-    json j_key = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & parsed)
-    {
-        return !(event == json::parse_event_t::key && parsed == json("Width"));
-    });
-
-    // discard the top-level object
-    json j_root = json::parse(text, [](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
-    {
-        return event != json::parse_event_t::object_end;
-    });
-
-    // in every case, the discarded value is removed together with its key
-    std::cout << j_array_start << '\n'
-              << j_array_end << '\n'
-              << j_value << '\n'
-              << j_key << '\n'
-              << j_root << '\n';
-}
@@ -1,5 +0,0 @@
-{"Width":800}
-{"Width":800}
-{"IDs":[116,943]}
-{"IDs":[116,943]}
-null
@@ -215,6 +215,24 @@ For _derived_ classes and structs, use the following macros
    nlohmann::ordered_json j = p; // keys appear in declaration order: name, address, age
    ```

+!!! note "Zero-member types"
+
+    All 12 `NLOHMANN_DEFINE_TYPE_*`/`NLOHMANN_DEFINE_DERIVED_TYPE_*` macros (excluding the `WITH_NAMES` variants)
+    also accept types with no member variables to serialize, producing/accepting an empty JSON object `{}`
+    (or, for the derived-type macros, just the base class's own JSON representation):
+
+    ```cpp
+    namespace ns {
+        struct marker {
+            bool operator==(const marker&) const { return true; }
+            NLOHMANN_DEFINE_TYPE_INTRUSIVE(marker)
+        };
+    }
+
+    ns::marker m{};
+    nlohmann::json j = m; // {}
+    ```
+
 !!! note "No macro for non-default-constructible types"

    There is currently no `NLOHMANN_DEFINE_TYPE_*`-style macro for types that are not
@@ -116,24 +116,9 @@ The library uses the following mapping from JSON values types to BJData types ac
    ```

    Likewise, when a JSON object in the above form is serialized using
-    [`to_bjdata`](../../api/basic_json/to_bjdata.md), it is automatically converted into a compact BJData ND-array.
-
-    When parsing, an ND-array whose dimension vector is empty, contains a single integer, contains two integers with the
-    first being 1, or contains a 0 is returned as a regular (possibly empty) array rather than an annotated object.
-
-    An object is only converted if the annotation describes a packed array that is parsed back into the same annotated
-    object; otherwise it is serialized as a regular JSON object, so the annotation is never lost in a round trip. This requires
-    all of the following:
-
-    - `"_ArrayType_"` is one of `uint8`, `int8`, `uint16`, `int16`, `uint32`, `int32`, `uint64`, `int64`, `single`,
-      `double`, `char`, or `byte`,
-    - `"_ArraySize_"` is an array, since the dimensions are written as the ND-array header's length,
-    - `"_ArraySize_"` has at least two entries and is not a 1×N row vector (first entry 1), since other shapes are
-      parsed back as a regular array,
-    - every entry of `"_ArraySize_"` is a positive integer, and their product is representable as a `std::size_t`,
-    - `"_ArrayData_"` is an array holding exactly that many elements, and
-    - every element of `"_ArrayData_"` is a number of the kind named by `"_ArrayType_"` (a floating-point number for
-      `single` and `double`, an integer otherwise).
+    [`to_bjdata`](../../api/basic_json/to_bjdata.md), it is automatically converted into a compact BJData ND-array. The
+    only exception is, that when the 1-dimensional vector stored in `"_ArraySize_"` contains a single integer or two
+    integers with one being 1, a regular 1-D optimized array is generated.

    The current version of this library does not yet support automatic detection of and conversion from a nested JSON
    array input to a BJData ND-array.
@@ -208,16 +193,6 @@ The library maps BJData types to JSON value types as follows:

    The mapping is **complete** in the sense that any BJData value can be converted to a JSON value.

-!!! info "Round trips"
-
-    A value returned by [`from_bjdata`](../../api/basic_json/from_bjdata.md) can be serialized with
-    [`to_bjdata`](../../api/basic_json/to_bjdata.md) using any combination of options and parsed back into an equal
-    value, and serializing that value again with the same options produces the same bytes. The exception is binary
-    values: they are only written as an optimized binary array (`[$B`) if Draft 3 is enabled and both `use_size` and
-    `use_type` are set. Otherwise, they are written as arrays of integers and parsed back as such (see the notes on
-    binary values above), and serializing such an array again may choose different, but equally valid, type markers.
-    The bytes can then differ, but parsing them again yields the same value.
-
 ??? example

    ```cpp
@@ -35,19 +35,6 @@ The library uses the following mapping from JSON values types to BSON types:
    The mapping is **incomplete**, since only JSON-objects (and things contained therein) can be serialized to BSON.
    Also, keys may not contain U+0000, since they are serialized a zero-terminated c-strings.

-!!! warning "BSON type 0x11 interoperability"
-
-    The BSON specification defines type `0x11` as a Timestamp. This library uses marker `0x11` when serializing
-    `number_unsigned` values in the range `9223372036854775808..18446744073709551615`. Other BSON implementations may
-    therefore interpret these values as Timestamps instead of unsigned integers.
-
-!!! info "Binary values without a subtype"
-
-    BSON requires every binary value to have a subtype. If a binary value has no subtype, this library serializes it
-    with the generic subtype `0x00`. After deserialization, `has_subtype()` returns `true` and `subtype()` returns `0`.
-    As a result, serializing and deserializing a JSON object containing such a value produces a different JSON object,
-    even though the binary data is unchanged.
-
 ??? example

    ```cpp
@@ -95,19 +82,8 @@ The library maps BSON record types to JSON value types as follows:

 !!! note "Handling of BSON type 0x11"

-    This library deserializes BSON type `0x11` (Timestamp) as a `number_unsigned` value. The 64-bit value is preserved,
-    but the Timestamp type information is not.
-
-!!! warning "Lenient BSON input handling"
-
-    The BSON reader is lenient in a few areas where the BSON specification is more restrictive:
-
-    - array element keys are not checked against the required decimal sequence (`0`, `1`, `2`, ...),
-    - any non-zero byte is accepted as `true` for the boolean type, and
-    - the payload for binary subtype `0x02` is returned as-is, including its inner length prefix.
-
-    If BSON input must be validated for strict specification compliance, validate it separately before passing it to
-    `from_bson()`.
+    BSON type 0x11 is used to represent uint64 numbers. This library treats these values purely as uint64 numbers 
+    and does not parse them into date-related formats.

 ??? example

@@ -7,12 +7,12 @@ extremely small code sizes, fairly small message size, and extensibility without

    - [CBOR Website](http://cbor.io) - the main source on CBOR
    - [CBOR Playground](http://cbor.me) - an interactive webpage to translate between JSON and CBOR
-    - [RFC 8949](https://www.rfc-editor.org/rfc/rfc8949.html) - the CBOR specification
+    - [RFC 7049](https://tools.ietf.org/html/rfc7049) - the CBOR specification

 ## Serialization

 The library uses the following mapping from JSON values types to CBOR types according to the CBOR specification
-([RFC 8949](https://www.rfc-editor.org/rfc/rfc8949.html)):
+([RFC 7049](https://www.rfc-editor.org/rfc/rfc7049.html)):

 | JSON value type | value/range                                | CBOR type                         | first byte |
 |-----------------|--------------------------------------------|-----------------------------------|------------|
@@ -160,11 +160,14 @@ The library maps CBOR types to JSON value types as follows:

    The mapping is **incomplete** in the sense that not all CBOR types can be converted to a JSON value. The following CBOR types are not supported and will yield parse errors:

+     - date/time (0xC0..0xC1)
+     - bignum (0xC2..0xC3)
+     - decimal fraction (0xC4)
+     - bigfloat (0xC5)
+     - expected conversions (0xD5..0xD7)
     - simple values (0xE0..0xF3, 0xF8)
     - undefined (0xF7)

-    Tagged items (0xC0..0xDB) are not interpreted either; see the note on tagged items below.
-
 !!! warning "Negative integer overflow"

    CBOR negative integers (major type 1) are decoded as `-1 - n`. If the encoded magnitude `n` is too large for the
@@ -178,7 +181,7 @@ The library maps CBOR types to JSON value types as follows:

 !!! warning "Tagged items"

-    Tagged items (0xC0..0xDB) will throw a parse error by default. They can be ignored by passing `cbor_tag_handler_t::ignore` to function `from_cbor`, in which case the tag is skipped and the enclosed data item is parsed on its own. They can be stored by passing `cbor_tag_handler_t::store` to function `from_cbor`. Note that no tag is ever interpreted: for instance, a text string tagged with tag 0 (date/time) stays a string.
+    Tagged items will throw a parse error by default. They can be ignored by passing `cbor_tag_handler_t::ignore` to function `from_cbor`. They can be stored by passing `cbor_tag_handler_t::store` to function `from_cbor`.

 ??? example

@@ -69,13 +69,6 @@ The library uses the following mapping from JSON values types to UBJSON types ac
    Note that `use_size = true` alone may result in larger representations - the benefit of this parameter is that the
    receiving side is immediately informed on the number of elements of the container.

-    An array whose type marker is `Z` (null), `T` (true) or `F` (false) stores no payload at all, because the marker
-    already is the value. Its declared count is therefore the only thing that decides how much memory the receiving side
-    allocates, and a handful of bytes can describe billions of elements. `from_ubjson` rejects such an array with
-    [`out_of_range.408`](../../home/exceptions.md#jsonexceptionout_of_range408) when the count exceeds 1,048,576
-    (`1 << 20`), and `to_ubjson` writes longer arrays of these types without the annotation, so any value it produces
-    can be read back.
-
 !!! info "Binary values"

    If the JSON data contains the binary type, the value stored is a list of integers, as suggested by the UBJSON
@@ -47,58 +47,6 @@ json j = {{"one", 1}, {"two", 2}};
 auto m = j.get<std::map<std::string, int>>();  // {{"one", 1}, {"two", 2}}
 ```

-`#!cpp std::pair` and `#!cpp std::tuple` are also supported, converting positionally to and from a JSON array:
-
-```cpp
-json j = {1.0, "hello", 42};
-auto t = j.get<std::tuple<double, std::string, int>>();  // {1.0, "hello", 42}
-```
-
-!!! warning "Serializing a `std::pair`/`std::tuple` whose every element is a string-keyed pair"
-
-    When *every* element of a `#!cpp std::pair` or `#!cpp std::tuple` is itself a two-element array whose first
-    element is a string (for example `#!cpp std::pair<std::string, int>`), serializing it produces a JSON **object**
-    instead of the expected array:
-
-    ```cpp
-    using kv = std::pair<std::string, int>;
-    json j = std::pair<kv, kv>{{"a", 1}, {"b", 2}};  // {"a":1,"b":2}, not [["a",1],["b",2]]
-    ```
-
-    This is a consequence of the [brace-initializer object-detection rule](creating_values.md): the same rule that
-    lets `#!cpp json{{"a", 1}, {"b", 2}}` create an object also fires here. The resulting object cannot be read back
-    into the original type (`#!cpp get<std::pair<kv, kv>>()` throws [`type_error.302`](../home/exceptions.md#jsonexceptiontype_error302)),
-    and duplicate keys collapse into one, losing elements. This only affects `#!cpp std::pair`/`#!cpp std::tuple`
-    themselves; a `#!cpp std::vector<std::pair<std::string, int>>`, or a pair/tuple with at least one element that is
-    not a string-keyed pair, serializes to an array as expected. To force an array, build one explicitly from the
-    elements with [`array`](../api/basic_json/array.md):
-
-    ```cpp
-    std::pair<kv, kv> p{{"a", 1}, {"b", 2}};
-    json a = json::array({p.first, p.second});  // [["a",1],["b",2]]
-    ```
-
-!!! info "Extracting references into a tuple"
-
-    A tuple type may also hold references (e.g. `#!cpp std::tuple<double&, std::string&>`) to avoid copying: `get`
-    then returns a tuple of references pointing directly at the elements stored inside the `basic_json` array,
-    rather than a tuple of copies:
-
-    ```cpp
-    json j = {1.0, "hello"};
-    auto refs = j.get<std::tuple<double&, std::string&>>();
-    std::get<1>(refs) = "world";  // modifies j[1] in place
-    ```
-
-    A referenced element must name the type the library actually *stores* — one of [`boolean_t`](../api/basic_json/boolean_t.md),
-    [`number_integer_t`](../api/basic_json/number_integer_t.md), [`number_unsigned_t`](../api/basic_json/number_unsigned_t.md),
-    [`number_float_t`](../api/basic_json/number_float_t.md), [`string_t`](../api/basic_json/string_t.md),
-    [`binary_t`](../api/basic_json/binary_t.md), [`array_t`](../api/basic_json/array_t.md), or
-    [`object_t`](../api/basic_json/object_t.md). There is nothing else to refer to, so a reference to any other type is a
-    compile error even when a conversion would exist: `#!cpp std::tuple<int&>` is rejected, because the library stores a
-    `#!cpp number_integer_t` (`#!cpp std::int64_t` by default) and not an `#!cpp int`. This restriction applies only to
-    reference elements — a plain `#!cpp std::tuple<int>` converts by value as usual.
-
 ## Implicit conversions

 By default, a JSON value implicitly converts to a compatible C++ type, so the explicit `get` call can often be omitted:
@@ -146,34 +94,17 @@ which forces the explicit `get` form and can catch unintended conversions at com
    with a custom `adl_serializer<std::optional<T>>` specialization. Prefer `get<std::optional<T>>()`/`get_to()`
    over `static_cast` for optional types.

-!!! warning "Converting to a fixed-size destination does not check the array size"
+!!! warning "Converting to a fixed-size `std::array` does not check length"

-    Some destination types have a size that is fixed by their C++ type rather than by the JSON value:
-    `#!cpp std::pair<A, B>`, `#!cpp std::tuple<Ts...>`, `#!cpp std::array<T, N>`, C arrays `#!cpp T[N]`, and
-    `#!cpp std::map`/`#!cpp std::unordered_map` with a non-string key type (which is read from an array of
-    two-element arrays). All of them read exactly as many elements as they need via
-    [`at`](../api/basic_json/at.md) and **never compare the JSON array's size to that number**. The two
-    mismatch directions therefore behave differently:
-
-    - The JSON array has **too many** elements: the surplus is **silently discarded**, and no exception is
-      thrown.
-    - The JSON array has **too few** elements: `at` throws
-      [`out_of_range.401`](../home/exceptions.md#jsonexceptionout_of_range401) for the first missing index --
-      an out-of-range error, not a [`type_error`](../home/exceptions.md#type-errors), even though the cause
-      is a shape mismatch.
+    Converting a JSON array to `#!cpp std::array<T, N>` does not check that the JSON array's size matches `N`:
+    if the JSON array is longer, the extra elements are silently dropped; if it is shorter, the remaining
+    `std::array` elements are left default-constructed. No exception is thrown in either case.

    ```cpp
    json j = {1, 2, 3, 4, 5};
-
-    auto a = j.get<std::array<int, 3>>();       // {1, 2, 3} -- elements 4 and 5 silently dropped
-    auto p = j.get<std::pair<int, int>>();      // (1, 2)    -- elements 3, 4, and 5 silently dropped
-
-    json k = {1};
-    auto q = k.get<std::pair<int, int>>();      // ❌ throws out_of_range.401
+    auto a = j.get<std::array<int, 3>>();  // {1, 2, 3} -- elements 4 and 5 silently dropped
    ```

-    If a size mismatch is an error in your application, check the size yourself before converting.
-
 ## Omitting a field when serializing `std::optional`

 By default, `to_json` for `std::optional<T>` writes either the value or `#!json null` -- there is no built-in way
@@ -205,20 +136,6 @@ std::vector<int> numbers = {1, 2, 3};
 json j = numbers;   // [1,2,3]
 ```

-!!! info "Constructing from a C++20 range view"
-
-    A `json` array can also be constructed directly from a C++20 range view (`std::ranges::view`), such as the result
-    of `std::views::filter` or `std::views::transform` -- no intermediate container is needed:
-
-    ```cpp
-    std::vector<int> nums{1, 2, 37, 42, 21};
-    auto filtered = nums | std::views::filter([](int i) { return i > 10; });
-    json j(filtered);   // [37,42,21]
-    ```
-
-    This requires [`JSON_HAS_RANGES`](../api/macros/json_has_ranges.md) to be enabled and is unavailable on MinGW due
-    to incomplete C++20 ranges support there.
-
 ## Your own types

 The conversions above are built in for standard types. To make the same syntax work for **your own** types, provide
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Niels Lohmann	98848ba230	Test for EMPTY and MEMBERS so -Wunused-macros accepts them Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-24 09:38:18 +02:00
Niels Lohmann	ce210a3419	Keep user macros named EMPTY or MEMBERS out of the member-count dispatch The dispatch produced the bare token EMPTY or MEMBERS and pasted it onto the macro prefix afterwards. In between, the token was rescanned, so a user macro with either name replaced it: with `#define MEMBERS x` in scope, even NLOHMANN_DEFINE_TYPE_INTRUSIVE(A, member) -- which compiled before -- expanded to garbage, and `#define EMPTY` broke the zero-member form. Paste the suffix onto the prefix directly in the GET_MACRO slot table instead. Operands of ## are not macro-expanded, so the selected body name is formed before any user macro can interfere. NLOHMANN_JSON_TYPE_TAG and NLOHMANN_JSON_DERIVED_TYPE_TAG become NLOHMANN_JSON_TYPE_BODY and NLOHMANN_JSON_DERIVED_TYPE_BODY, taking the prefix as their first argument; NLOHMANN_JSON_CAT is no longer needed. The body macro names are unchanged, and so is the generated code. Add a regression test that defines EMPTY and MEMBERS around plain and derived types, with and without members. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-23 20:28:37 +02:00
Niels Lohmann	f8a0990582	Document zero-member support in the macro API reference docs/mkdocs/docs/features/arbitrary_types.md already gained a note, but the three api/macros pages are where the parameter contract is actually specified and they still described member as a non-empty list. State that the list may be empty on each page, and add a note showing what the zero-member case generates: an empty JSON object for the plain macros, and base-type-only serialization for the derived ones. Both notes record that the WITH_NAMES variants do not support this. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-08-20 09:01:11 +02:00
Niels Lohmann	7e87e5920f	Name the zero-member macro bodies by intent, not argument count The dispatch tag was the literal token 1 or N, pasted onto a macro prefix to select the zero-member or member-carrying body. For the derived-type macros that reads wrong: their tag is computed after dropping the leading Type, so the zero-member body was named _1 while taking two parameters (Type, BaseType). Emit EMPTY and MEMBERS instead. The mechanism is unchanged -- the tag is still a token pasted onto the prefix by NLOHMANN_JSON_CAT -- but the body names now say what they are rather than encoding an argument count that only lines up for half of the macros. Collapse the four duplicated zero-member bodies while here: with no members there is nothing to default, so each _WITH_DEFAULT_EMPTY body was a byte-for-byte copy of its plain counterpart. They are now one-line aliases, leaving a single definition of what an empty object serializes to per intrusive/non-intrusive and base/derived combination. No functional change: for both zero-member and member-carrying types the preprocessed to_json/from_json output is token-for-token identical, and the arity limits are unchanged (63 members, base and derived). Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-08-19 23:05:45 +02:00
Niels Lohmann	0b28c63bad	Fix derived-type macro dispatch capping members at 62 instead of 63 NLOHMANN_JSON_GET_MACRO resolves 64 positional arguments, with NAME at position 65. NLOHMANN_JSON_TYPE_TAG dispatches on Type plus the member list, so it resolves correctly up to the 63 members NLOHMANN_JSON_PASTE supports. NLOHMANN_JSON_DERIVED_TYPE_TAG dispatched on the two-token Type,BaseType prefix plus the member list, running out one slot early: at 63 members, position 65 landed on the last member name instead of a sentinel and NLOHMANN_JSON_CAT built an undefined identifier such as NLOHMANN_JSON_DEFINE_DERIVED_TYPE_INTRUSIVE_m63, with the compiler reporting "unknown type name 'm1'" once per member and nothing pointing at an argument-count limit. That silently reduced all six NLOHMANN_DEFINE_DERIVED_TYPE_* macros from 63 members to 62, contradicting the "up to 63 members" contract in docs/mkdocs/docs/api/macros/nlohmann_define_derived_type.md. Drop the leading Type and defer to NLOHMANN_JSON_TYPE_TAG so the tag is computed from BaseType plus the member list, which fits the available slots. The zero-own-member derived bodies are therefore selected by tag 1 rather than 2, and the sentinel table for the derived tag is no longer needed. Add a regression test at the documented maximum for both the plain and the derived macros; it fails to compile against the previous dispatch. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-08-19 21:03:08 +02:00
Niels Lohmann	4dcd45b26d	Fix clang-tidy misc-const-correctness in unit-udt_macro.cpp The four zero-member ONLY_SERIALIZE test objects are only ever read (via to_json), never mutated, so mark them const per clang-tidy. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-07-12 06:37:49 +00:00
Niels Lohmann	9d83673263	Fix CI failures in zero-member NLOHMANN_DEFINE_TYPE_* macros Three issues surfaced on PR #5272's real CI that weren't caught by local testing against a narrower flag set: - GCC -Werror=noexcept: the four truly-empty from_json bodies (plain INTRUSIVE/NON_INTRUSIVE, with and without _WITH_DEFAULT) provably never throw but weren't declared noexcept; mark them noexcept explicitly. to_json and the derived-type from_json overloads are left alone since they genuinely can throw (object assignment / delegating to the base class's from_json). - clang-tidy bugprone-macro-parentheses: false positive on the same 8 zero-member bodies (Type/BaseType used purely as declarator types); suppressed with NOLINTNEXTLINE comments in the same style already used elsewhere in this file (see NLOHMANN_JSON_SERIALIZE_ENUM). - MSVC's traditional preprocessor doesn't fully expand NLOHMANN_JSON_CAT(prefix, NLOHMANN_JSON_TYPE_TAG(...))(...) in one pass, which broke a pre-existing one-member usage in unit-regression2.cpp with syntax errors. Wrap all 12 public dispatcher macros in an extra outer NLOHMANN_JSON_EXPAND(...), matching the pattern NLOHMANN_JSON_PASTE already uses for the same MSVC quirk. Re-verified against real GCC 16 and Clang at -std=c++11/14/17/20 with -pedantic -Werror -Wvariadic-macros -Wnoexcept, including the exact files that failed in CI (unit-udt_macro.cpp, unit-regression2.cpp), against both the modular headers and the re-amalgamated single header. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-07-11 23:55:43 +02:00
Niels Lohmann	d969eef216	Support zero-member types in NLOHMANN_DEFINE_TYPE_* macros (#4041 ) NLOHMANN_DEFINE_TYPE_INTRUSIVE(Type) and its 11 sibling macros produced broken code for types with no members to serialize. Invoking a variadic macro so __VA_ARGS__ is empty is only standard-conforming since C++20, so a plain __VA_OPT__ fix (as tried in #5142) breaks every pre-C++20 build under -pedantic. Instead, make all 12 macros purely variadic and dispatch on argument count using a sentinel-padded extension of the existing NLOHMANN_JSON_GET_MACRO idiom, giving full C++11-C++26 support with no feature-test gate. Verified against real GCC 16 and Clang at -std=c++11/14/17/20 with -pedantic -Werror -Wvariadic-macros: zero regressions in the existing unit-udt_macro.cpp suite plus 12 new zero-member test cases. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-07-11 19:55:56 +02:00