Bump the codeql-action group with 4 updates

Bumps the codeql-action group with 4 updates: [github/codeql-action/init](https://github.com/github/codeql-action), [github/codeql-action/autobuild](https://github.com/github/codeql-action), [github/codeql-action/analyze](https://github.com/github/codeql-action) and [github/codeql-action/upload-sarif](https://github.com/github/codeql-action). Updates `github/codeql-action/init` from 4.38.1 to 4.38.2 - [Release notes](https://github.com/github/codeql-action/releases) - [Changelog](https://github.com/github/codeql-action/blob/main/CHANGELOG.md) - [Commits](https://github.com/github/codeql-action/compare/1c5b675653bb5c22dbe9b12b556ec555138e09fd...2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2) Updates `github/codeql-action/autobuild` from 4.38.1 to 4.38.2 - [Release notes](https://github.com/github/codeql-action/releases) - [Changelog](https://github.com/github/codeql-action/blob/main/CHANGELOG.md) - [Commits](https://github.com/github/codeql-action/compare/1c5b675653bb5c22dbe9b12b556ec555138e09fd...2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2) Updates `github/codeql-action/analyze` from 4.38.1 to 4.38.2 - [Release notes](https://github.com/github/codeql-action/releases) - [Changelog](https://github.com/github/codeql-action/blob/main/CHANGELOG.md) - [Commits](https://github.com/github/codeql-action/compare/1c5b675653bb5c22dbe9b12b556ec555138e09fd...2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2) Updates `github/codeql-action/upload-sarif` from 4.38.1 to 4.38.2 - [Release notes](https://github.com/github/codeql-action/releases) - [Changelog](https://github.com/github/codeql-action/blob/main/CHANGELOG.md) - [Commits](https://github.com/github/codeql-action/compare/1c5b675653bb5c22dbe9b12b556ec555138e09fd...2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2) --- updated-dependencies: - dependency-name: github/codeql-action/init dependency-version: 4.38.2 dependency-type: direct:production update-type: version-update:semver-patch dependency-group: codeql-action - dependency-name: github/codeql-action/autobuild dependency-version: 4.38.2 dependency-type: direct:production update-type: version-update:semver-patch dependency-group: codeql-action - dependency-name: github/codeql-action/analyze dependency-version: 4.38.2 dependency-type: direct:production update-type: version-update:semver-patch dependency-group: codeql-action - dependency-name: github/codeql-action/upload-sarif dependency-version: 4.38.2 dependency-type: direct:production update-type: version-update:semver-patch dependency-group: codeql-action ... Signed-off-by: dependabot[bot] <support@github.com>
Fix update() and merge_patch() when the argument is *this or one of its members (#5678 )
2026-10-01 20:20:32 +00:00 · 2026-10-01 05:03:47 +00:00 · 2026-09-30 23:04:57 +02:00 · 2026-09-30 22:49:24 +02:00 · 2026-09-30 22:48:32 +02:00 · 2026-09-30 22:21:27 +02:00
74 changed files with 3660 additions and 2380 deletions
@@ -1,17 +0,0 @@
-arm_container:
-  image: gcc:latest
-
-check_task:
-  check_script:
-  # the gcc image ships an outdated CMake, so fetch a recent prebuilt binary
-  # instead of compiling CMake from source
-  - wget -q https://github.com/Kitware/CMake/releases/download/v4.3.4/cmake-4.3.4-linux-aarch64.tar.gz
-  - tar xfz cmake-4.3.4-linux-aarch64.tar.gz
-  - export PATH="$(pwd)/cmake-4.3.4-linux-aarch64/bin:$PATH"
-  - cmake --version
-  - mkdir build
-  - cd build
-  - cmake .. -DJSON_FastTests=ON
-  - make -j4
-  - cd tests
-  - ctest -j4
@@ -24,6 +24,10 @@ updates:
      interval: daily
    cooldown:
      default-days: 7
+    ignore:
+      # astyle is deliberately pinned (see tools/astyle/requirements.txt): newer versions
+      # reformat the code, and the pinned version defines the formatting CI enforces
+      - dependency-name: astyle

  - package-ecosystem: pip
    directory: /tools/generate_natvis
@@ -30,14 +30,6 @@ environment:
      CMAKE_OPTIONS: ""
      GENERATOR: Visual Studio 14 2015

-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      configuration: Release
-      platform: x86
-      name: with_win_header
-      CXX_FLAGS: "/W4 /WX"
-      CMAKE_OPTIONS: ""
-      GENERATOR: Visual Studio 14 2015
-
    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
      configuration: Release
      platform: x86
@@ -74,9 +66,6 @@ install:
  - if "%platform%"=="x86"    set GENERATOR_PLATFORM=Win32

 before_build:
-  # for with_win_header build, inject the inclusion of Windows.h to the single-header library
-  - ps: if ($env:name -Eq "with_win_header") { $header_path = "single_include\nlohmann\json.hpp" }
-  - ps: if ($env:name -Eq "with_win_header") { "#include <Windows.h>`n" + (Get-Content $header_path | Out-String) | Set-Content $header_path }
  - cmake . -G "%GENERATOR%" -A "%GENERATOR_PLATFORM%" -DCMAKE_CXX_FLAGS="%CXX_FLAGS%" -DCMAKE_IGNORE_PATH="C:/Program Files/Git/usr/bin" -DJSON_BuildTests=On "%CMAKE_OPTIONS%"

 build_script:
@@ -35,6 +35,7 @@ jobs:
      MAIN_DIR: ${{ github.workspace }}/main
      INCLUDE_DIR: ${{ github.workspace }}/main/single_include/nlohmann
      TOOL_DIR: ${{ github.workspace }}/tools/tools/amalgamate
+      NATVIS_TOOL_DIR: ${{ github.workspace }}/tools/tools/generate_natvis

    steps:
      - name: Harden Runner
@@ -61,6 +62,48 @@ jobs:
          python3 -mvenv venv
          venv/bin/pip3 install -r $MAIN_DIR/tools/astyle/requirements.txt

+      - name: Install generate_natvis dependencies
+        run: pip3 install -r $NATVIS_TOOL_DIR/requirements.txt
+
+      - name: Regenerate the tools/macro_builder tables in macro_scope.hpp
+        run: |
+          cd $MAIN_DIR
+
+          # Built from this PR's own tools/macro_builder/main.cpp, not a
+          # develop checkout: unlike amalgamate.py and generate_natvis.py,
+          # this tool has no other source of truth to check against (its
+          # own README documents that it must reproduce macro_scope.hpp
+          # byte for byte), so there is nothing to gain from checking out a
+          # separate copy, and doing so would make this step fail on a PR
+          # that adds support for a new dispatch table until that PR itself
+          # merges to develop, the same way generate_natvis.py's --version
+          # requirement briefly did.
+          TMPDIR=$(mktemp -d ./macro_builder_check.XXXXXX)
+          c++ -std=c++11 tools/macro_builder/main.cpp -o "$TMPDIR/macro_builder"
+          "$TMPDIR/macro_builder" > "$TMPDIR/paste.hpp"
+          "$TMPDIR/macro_builder" type_body > "$TMPDIR/type_body.hpp"
+
+          # Splice the (still unindented) generated blocks back into
+          # macro_scope.hpp; the astyle pass below indents their
+          # continuation lines the same way it does for the rest of
+          # include/, so a correctly regenerated file comes out unchanged.
+          awk -v newfile="$TMPDIR/paste.hpp" '
+            BEGIN { while ((getline line < newfile) > 0) { new = new line "\n" } }
+            /^#define NLOHMANN_JSON_EXPAND\( x \) x$/ { printf "%s", new; skip=1 }
+            skip && /^#define NLOHMANN_JSON_DOUBLE_PASTE63\(/ { skip=0; next }
+            skip { next }
+            { print }
+          ' include/nlohmann/detail/macro_scope.hpp > "$TMPDIR/macro_scope_1.hpp"
+          awk -v newfile="$TMPDIR/type_body.hpp" '
+            BEGIN { while ((getline line < newfile) > 0) { new = new line "\n" } }
+            /^#define NLOHMANN_JSON_TYPE_BODY\(Prefix, \.\.\.\)/ { printf "%s", new; skip=1 }
+            skip && /^[[:space:]]*NLOHMANN_JSON_TYPE_BODY_SENTINEL\)\)$/ { skip=0; next }
+            skip { next }
+            { print }
+          ' "$TMPDIR/macro_scope_1.hpp" > "$TMPDIR/macro_scope_2.hpp"
+          mv "$TMPDIR/macro_scope_2.hpp" include/nlohmann/detail/macro_scope.hpp
+          rm -rf "$TMPDIR"
+
      - name: Regenerate amalgamation, formatting, and BUILD.bazel
        run: |
          cd $MAIN_DIR
@@ -88,6 +131,19 @@ jobs:
          ${{ 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)

+      - name: Regenerate nlohmann_json.natvis
+        run: |
+          cd $MAIN_DIR
+          # Pass --version explicitly so this step also works with the tool
+          # copy from develop before this repository's own generate_natvis.py
+          # learns to derive the version itself: the older script requires
+          # --version, and the newer one accepts it as an explicit override.
+          ABI_MACROS=include/nlohmann/detail/abi_macros.hpp
+          VERSION_MAJOR=$(grep -m1 'define NLOHMANN_JSON_VERSION_MAJOR' $ABI_MACROS | grep -o '[0-9]\+')
+          VERSION_MINOR=$(grep -m1 'define NLOHMANN_JSON_VERSION_MINOR' $ABI_MACROS | grep -o '[0-9]\+')
+          VERSION_PATCH=$(grep -m1 'define NLOHMANN_JSON_VERSION_PATCH' $ABI_MACROS | grep -o '[0-9]\+')
+          python3 $NATVIS_TOOL_DIR/generate_natvis.py --version "$VERSION_MAJOR.$VERSION_MINOR.$VERSION_PATCH" $MAIN_DIR
+
      - name: Build patch and check for differences
        id: diff
        run: |
@@ -38,14 +38,14 @@ jobs:

    # Initializes the CodeQL tools for scanning.
    - name: Initialize CodeQL
-      uses: github/codeql-action/init@1c5b675653bb5c22dbe9b12b556ec555138e09fd # v4.38.1
+      uses: github/codeql-action/init@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
      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@1c5b675653bb5c22dbe9b12b556ec555138e09fd # v4.38.1
+      uses: github/codeql-action/autobuild@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2

    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@1c5b675653bb5c22dbe9b12b556ec555138e09fd # v4.38.1
+      uses: github/codeql-action/analyze@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
@@ -47,6 +47,6 @@ jobs:
          output: 'flawfinder_results.sarif'

      - name: Upload analysis results to GitHub Security tab
-        uses: github/codeql-action/upload-sarif@1c5b675653bb5c22dbe9b12b556ec555138e09fd # v4.38.1
+        uses: github/codeql-action/upload-sarif@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
        with:
          sarif_file: ${{github.workspace}}/flawfinder_results.sarif
@@ -7,6 +7,16 @@ on:
      - develop
    paths:
      - docs/mkdocs/**
+      # the site also embeds these files via pymdownx.snippets
+      # (mkdocs.yml sets restrict_base_path: false for this)
+      - .clang-tidy
+      - .github/CODE_OF_CONDUCT.md
+      - .github/CONTRIBUTING.md
+      - .github/SECURITY.md
+      - cmake/clang_flags.cmake
+      - cmake/gcc_flags.cmake
+      - tests/fmt_formatter/project/main.cpp
+      - tools/astyle/.astylerc
  workflow_dispatch:

 # we don't want to have concurrent jobs, and we don't want to cancel running jobs to avoid broken publications
@@ -23,7 +33,7 @@ jobs:
      contents: write

    if: github.repository == 'nlohmann/json'
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
@@ -31,6 +41,8 @@ jobs:
          egress-policy: audit

      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false

      - name: Install virtual environment
        run: make install_venv -C docs/mkdocs
@@ -80,6 +80,6 @@ jobs:

      # Upload the results to GitHub's code scanning dashboard.
      - name: "Upload to code-scanning"
-        uses: github/codeql-action/upload-sarif@1c5b675653bb5c22dbe9b12b556ec555138e09fd # v4.38.1
+        uses: github/codeql-action/upload-sarif@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
        with:
          sarif_file: results.sarif
@@ -65,7 +65,7 @@ jobs:

      # Upload SARIF file generated in previous step
      - name: Upload SARIF file
-        uses: github/codeql-action/upload-sarif@1c5b675653bb5c22dbe9b12b556ec555138e09fd # v4.38.1
+        uses: github/codeql-action/upload-sarif@2892aa5e19bbd11bc0cff5427e3b750a04d9e3c2 # v4.38.2
        with:
          sarif_file: semgrep.sarif
        if: always()
@@ -52,6 +52,13 @@ jobs:
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
        run: cmake --build build --target ci_infer
+      - name: Archive Infer report
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: infer-report
+          path: ${{ github.workspace }}/build/build_infer/infer-out/report.txt
+          if-no-files-found: ignore

  ci_static_analysis_ubuntu:
    runs-on: ubuntu-latest
@@ -97,13 +104,13 @@ jobs:

  ci_cmake_options:
    runs-on: ubuntu-latest
-    container: ubuntu:focal
+    container: ubuntu:24.04
    strategy:
      matrix:
-        target: [ci_cmake_flags, ci_test_diagnostics, ci_test_diagnostic_positions, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison, ci_test_noglobaludls, ci_test_disableenumserialization, ci_test_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, ci_test_disableenumserialization, ci_test_disabletuplereferenceconversion, ci_test_skiplibraryversioncheck, ci_test_simdutf, ci_test_strict_nul_handling, ci_test_no_thread_local]
    steps:
      - name: Install build-essential
-        run: apt-get update ; apt-get install -y build-essential unzip wget git libssl-dev
+        run: apt-get update ; apt-get install -y build-essential unzip wget git
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false
@@ -346,6 +353,8 @@ jobs:
    container: intel/oneapi-hpckit:latest
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
      - name: Get latest CMake and ninja
        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
      - name: Run CMake
@@ -358,6 +367,8 @@ jobs:
    container: nvcr.io/nvidia/nvhpc:25.5-devel-cuda12.9-ubuntu22.04
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
      - name: Get latest CMake and ninja
        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
      - name: Run CMake
@@ -403,3 +414,21 @@ jobs:
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
        run: cmake --build build --target ${{ matrix.target }}
+
+  # Native Linux ARM64 runner with the latest GCC. The ubuntu-24.04-arm label is
+  # only available for public repositories.
+  ci_test_arm64:
+    runs-on: ubuntu-24.04-arm
+    container: gcc:latest
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+      - name: Get latest CMake and ninja
+        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+      - name: Check that the job runs natively on arm64
+        run: uname -m && test "$(uname -m)" = aarch64
+      - name: Run CMake
+        run: cmake -S . -B build -DJSON_CI=On
+      - name: Build
+        run: cmake --build build --target ci_test_compiler_default
@@ -87,6 +87,8 @@ jobs:

    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
      - name: Get latest CMake and ninja
        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
      - name: Set extra CXX_FLAGS for latest std_version
@@ -123,6 +125,8 @@ jobs:

    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
      - name: Run CMake (Release)
        run: cmake -S . -B build -G "Visual Studio 18 2026" -A ARM64 -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="/W4 /WX"
        if: matrix.build_type == 'Release'
@@ -0,0 +1,12 @@
+{
+  "_comment": "Used by the ci_infer CMake target (#5715 item 4b). fail-on-issue makes CI fail on Infer findings; disable-issue-type is a type-level baseline for the ~174 pre-existing findings (all PULSE_UNNECESSARY_COPY*/PULSE_RESOURCE_LEAK/PULSE_CONST_REFABLE, mostly in test code) triaged in run https://github.com/nlohmann/json/actions/runs/35829411620 on commit 1054b2097, so CI fails only on a NEW issue type. Remove an entry here once its findings have been fixed or explicitly accepted.",
+  "fail-on-issue": true,
+  "disable-issue-type": [
+    "PULSE_UNNECESSARY_COPY_ASSIGNMENT",
+    "PULSE_UNNECESSARY_COPY",
+    "PULSE_UNNECESSARY_COPY_INTERMEDIATE",
+    "PULSE_UNNECESSARY_COPY_OPTIONAL",
+    "PULSE_RESOURCE_LEAK",
+    "PULSE_CONST_REFABLE"
+  ]
+}
@@ -55,6 +55,7 @@ option(JSON_Diagnostic_Positions           "Enable diagnostic positions." OFF)
 option(JSON_GlobalUDLs                     "Place user-defined string literals in the global namespace." ON)
 option(JSON_ImplicitConversions            "Enable implicit conversions." ON)
 option(JSON_DisableEnumSerialization       "Disable default integer enum serialization." OFF)
+option(JSON_DisableTupleReferenceConversion "Disable conversion from a one-element tuple of a JSON reference." OFF)
 option(JSON_LegacyDiscardedValueComparison "Enable legacy discarded value comparison." OFF)
 option(JSON_Install                        "Install CMake targets during install step." ${MAIN_PROJECT})
 option(JSON_MultipleHeaders                "Use non-amalgamated version of the library." ON)
@@ -101,6 +102,10 @@ if (JSON_DisableEnumSerialization)
    message(STATUS "Enum integer serialization is disabled (JSON_DISABLE_ENUM_SERIALIZATION=1)")
 endif()

+if (JSON_DisableTupleReferenceConversion)
+    message(STATUS "Tuple reference conversion is disabled (JSON_DISABLE_TUPLE_REFERENCE_CONVERSION=1)")
+endif()
+
 if (JSON_LegacyDiscardedValueComparison)
    message(STATUS "Legacy discarded value comparison enabled (JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1)")
 endif()
@@ -143,6 +148,7 @@ target_compile_definitions(
    $<$<NOT:$<BOOL:${JSON_GlobalUDLs}>>:JSON_USE_GLOBAL_UDLS=0>
    $<$<NOT:$<BOOL:${JSON_ImplicitConversions}>>:JSON_USE_IMPLICIT_CONVERSIONS=0>
    $<$<BOOL:${JSON_DisableEnumSerialization}>:JSON_DISABLE_ENUM_SERIALIZATION=1>
+    $<$<BOOL:${JSON_DisableTupleReferenceConversion}>:JSON_DISABLE_TUPLE_REFERENCE_CONVERSION=1>
    $<$<BOOL:${JSON_Diagnostics}>:JSON_DIAGNOSTICS=1>
    $<$<BOOL:${JSON_Diagnostic_Positions}>:JSON_DIAGNOSTIC_POSITIONS=1>
    $<$<BOOL:${JSON_LegacyDiscardedValueComparison}>:JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1>
@@ -33,17 +33,6 @@ Further documentation:
 > [!IMPORTANT]
 > The folder `.github/workflows` is predetermined by GitHub.

-### `.cirrus.yml`
-
-Configuration file for the pipeline at [Cirrus CI](https://cirrus-ci.com/github/nlohmann/json).
-
-Further documentation:
-
- [Writing tasks](https://cirrus-ci.org/guide/writing-tasks/)
-
-> [!IMPORTANT]
-> The filename `.cirrus.yml` and position (root of the repository) are predetermined by Cirrus CI.
-
 ### `.github/external_ci/appveyor.yml`

 Configuration for the pipelines at [AppVeyor](https://ci.appveyor.com/project/nlohmann/json).
@@ -1,4 +1,4 @@
-.PHONY: pretty clean ChangeLog.md release update_hedley update_hedley_undef BUILD.bazel
+.PHONY: pretty clean ChangeLog.md release update_hedley update_hedley_undef BUILD.bazel natvis macro_builder_check

 ##########################################################################
 # configuration
@@ -24,6 +24,9 @@ AMALGAMATED_FWD_FILE=single_include/nlohmann/json_fwd.hpp
 # json_literals.hpp only includes <nlohmann/json.hpp>, so it is copied verbatim
 AMALGAMATED_LITERALS_FILE=single_include/nlohmann/json_literals.hpp

+# the header with the argument-counting macros generated by tools/macro_builder
+MACRO_SCOPE_HPP=include/nlohmann/detail/macro_scope.hpp
+

 ##########################################################################
 # documentation of the Makefile's targets
@@ -36,13 +39,9 @@ all:
 	@echo "ChangeLog.md - generate ChangeLog file"
 	@echo "check-amalgamation - check whether sources have been amalgamated and BUILD.bazel is up to date"
 	@echo "clean - remove built files"
-	@echo "doctest - compile example files and check their output"
-	@echo "fuzz_testing - prepare fuzz testing of the JSON parser"
-	@echo "fuzz_testing_bon8 - prepare fuzz testing of the BON8 parser"
-	@echo "fuzz_testing_bson - prepare fuzz testing of the BSON parser"
-	@echo "fuzz_testing_cbor - prepare fuzz testing of the CBOR parser"
-	@echo "fuzz_testing_msgpack - prepare fuzz testing of the MessagePack parser"
-	@echo "fuzz_testing_ubjson - prepare fuzz testing of the UBJSON parser"
+	@echo "fuzzing - see tests/fuzzing.md for how to build and run the fuzzers"
+	@echo "macro_builder_check - check that macro_scope.hpp matches tools/macro_builder's output"
+	@echo "natvis - regenerate nlohmann_json.natvis from the current ABI tags and version"
 	@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"
@@ -61,74 +60,6 @@ run_benchmarks:
 	cd cmake-build-benchmarks ; ./json_benchmarks


-##########################################################################
-# fuzzing
-##########################################################################
-
-# the overall fuzz testing target
-fuzz_testing:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_afl_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_afl_fuzzer fuzz-testing/fuzzer
-	find tests/data/json_tests -size -5k -name *json | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_bon8:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_bon8_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_bon8_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.bon8 | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_bson:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_bson_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_bson_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.bson | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_cbor:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_cbor_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_cbor_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.cbor | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_msgpack:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_msgpack_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_msgpack_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.msgpack | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_ubjson:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_ubjson_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_ubjson_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.ubjson | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzzing-start:
-	afl-fuzz -S fuzzer1 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer2 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer3 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer4 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer5 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer6 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer7 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -M fuzzer0 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer
-
-fuzzing-stop:
-	-killall fuzzer
-	-killall afl-fuzz
-
-
 ##########################################################################
 # Static analysis
 ##########################################################################
@@ -156,11 +87,7 @@ install_astyle:

 # call the Artistic Style pretty printer on all source files
 pretty: install_astyle
-	$(ASTYLE) --project=tools/astyle/.astylerc $(SRCS) $(TESTS_SRCS) $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) docs/mkdocs/docs/examples/*.cpp
-
-# call the Clang-Format on all source files
-pretty_format:
-	for FILE in $(SRCS) $(TESTS_SRCS) $(AMALGAMATED_FILE) docs/mkdocs/docs/examples/*.cpp; do echo $$FILE; clang-format -i $$FILE; done
+	$(ASTYLE) --project=tools/astyle/.astylerc $(SRCS) $(TESTS_SRCS) $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) docs/mkdocs/docs/examples/*.cpp docs/mkdocs/docs/examples/*.hpp

 # create single header files and pretty print
 amalgamate: $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE)
@@ -178,8 +105,26 @@ $(AMALGAMATED_FWD_FILE): $(SRCS)
 $(AMALGAMATED_LITERALS_FILE): include/nlohmann/json_literals.hpp
 	cp include/nlohmann/json_literals.hpp $(AMALGAMATED_LITERALS_FILE)

+# regenerate nlohmann_json.natvis from the ABI tags and version in include/nlohmann/detail/abi_macros.hpp
+natvis:
+	python3 tools/generate_natvis/generate_natvis.py .
+
+# regenerate the two tools/macro_builder blocks of $(MACRO_SCOPE_HPP) (see its README.md) and diff against the
+# checked-in header; phony, because it never writes $(MACRO_SCOPE_HPP) itself
+macro_builder_check:
+	@set -e; \
+	TMPDIR=$$(mktemp -d ./macro_builder_check.XXXXXX); \
+	trap 'rm -rf "$$TMPDIR"' EXIT; \
+	$(CXX) -std=c++11 tools/macro_builder/main.cpp -o "$$TMPDIR/macro_builder"; \
+	"$$TMPDIR/macro_builder" > "$$TMPDIR/paste.hpp"; \
+	"$$TMPDIR/macro_builder" type_body > "$$TMPDIR/type_body.hpp"; \
+	$(ASTYLE) --project=tools/astyle/.astylerc --suffix=none --quiet "$$TMPDIR/paste.hpp" "$$TMPDIR/type_body.hpp"; \
+	sed -n '/^#define NLOHMANN_JSON_EXPAND( x ) x$$/,/^#define NLOHMANN_JSON_DOUBLE_PASTE63(/p' $(MACRO_SCOPE_HPP) > "$$TMPDIR/paste_actual.hpp"; \
+	sed -n '/^#define NLOHMANN_JSON_TYPE_BODY(Prefix, \.\.\.)/,/^        NLOHMANN_JSON_TYPE_BODY_SENTINEL))$$/p' $(MACRO_SCOPE_HPP) > "$$TMPDIR/type_body_actual.hpp"; \
+	diff "$$TMPDIR/paste.hpp" "$$TMPDIR/paste_actual.hpp" || (echo "===================================================================\n  $(MACRO_SCOPE_HPP) (NLOHMANN_JSON_EXPAND..NLOHMANN_JSON_DOUBLE_PASTE63) is out of date!\n  Regenerate it, see tools/macro_builder/README.md.\n===================================================================" ; exit 1); \
+	diff "$$TMPDIR/type_body.hpp" "$$TMPDIR/type_body_actual.hpp" || (echo "===================================================================\n  $(MACRO_SCOPE_HPP) (NLOHMANN_JSON_TYPE_BODY) is out of date!\n  Regenerate it, see tools/macro_builder/README.md.\n===================================================================" ; exit 1)
+
 # check if file single_include/nlohmann/json.hpp has been amalgamated from the nlohmann sources
-# Note: this target is called by Travis
 check-amalgamation:
 	@mv $(AMALGAMATED_FILE) $(AMALGAMATED_FILE)~
 	@mv $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_FWD_FILE)~
@@ -195,6 +140,11 @@ check-amalgamation:
 	@$(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
+	@mv nlohmann_json.natvis nlohmann_json.natvis~
+	@$(MAKE) natvis
+	@diff nlohmann_json.natvis nlohmann_json.natvis~ || (echo "===================================================================\n  nlohmann_json.natvis is out of date! Please run 'make natvis'.\n===================================================================" ; mv nlohmann_json.natvis~ nlohmann_json.natvis ; false)
+	@mv nlohmann_json.natvis~ nlohmann_json.natvis
+	@$(MAKE) macro_builder_check

 # generate the Bazel BUILD file; phony, because a removed header would not trigger a rebuild
 BUILD.bazel:
@@ -246,7 +196,7 @@ release: include.zip json.tar.xz
 	cp $(AMALGAMATED_FWD_FILE) release_files
 	cp $(AMALGAMATED_LITERALS_FILE) release_files
 	mv $(AMALGAMATED_FILE).asc $(AMALGAMATED_FWD_FILE).asc $(AMALGAMATED_LITERALS_FILE).asc json.tar.xz json.tar.xz.asc include.zip include.zip.asc release_files
-	cd release_files ; shasum -a 256 json.hpp include.zip json.tar.xz > hashes.txt
+	cd release_files ; shasum -a 256 $$(find . -type f -not -name '*.asc' | sed 's|^\./||' | sort) > hashes.txt


 ##########################################################################
@@ -256,7 +206,6 @@ release: include.zip json.tar.xz
 # clean up
 clean:
 	rm -fr fuzz fuzz-testing *.dSYM tests/*.dSYM
-	rm -fr benchmarks/files/numbers/*.json
 	rm -fr cmake-build-benchmarks fuzz-testing cmake-build-pvs-studio release_files
 	$(MAKE) clean -Cdocs

@@ -7,7 +7,6 @@
 [![Coverage Status](https://coveralls.io/repos/github/nlohmann/json/badge.svg?branch=develop)](https://coveralls.io/github/nlohmann/json?branch=develop)
 [![Coverity Scan Build Status](https://scan.coverity.com/projects/5550/badge.svg)](https://scan.coverity.com/projects/nlohmann-json)
 [![Codacy Badge](https://app.codacy.com/project/badge/Grade/e0d1a9d5d6fd46fcb655c4cb930bb3e8)](https://app.codacy.com/gh/nlohmann/json/dashboard?utm_source=gh&utm_medium=referral&utm_content=&utm_campaign=Badge_grade)
-[![Cirrus CI](https://api.cirrus-ci.com/github/nlohmann/json.svg)](https://cirrus-ci.com/github/nlohmann/json)
 [![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/json.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:json)
 [![Try online](https://img.shields.io/badge/try-online-blue.svg)](https://wandbox.org/permlink/1mp10JbaANo6FUc7)
 [![Documentation](https://img.shields.io/badge/docs-mkdocs-blue.svg)](https://json.nlohmann.me)
@@ -40,6 +40,14 @@ execute_process(COMMAND ${IWYU_TOOL} --version OUTPUT_VARIABLE IWYU_TOOL_VERSION
 string(REGEX MATCH "[0-9]+(\\.[0-9]+)+" IWYU_TOOL_VERSION "${IWYU_TOOL_VERSION}")
 message(STATUS "🔖 include-what-you-use ${IWYU_TOOL_VERSION} (${IWYU_TOOL})")

+# CMake's CXX_INCLUDE_WHAT_YOU_USE launcher runs IWYU during the normal compile step (useful to see
+# diagnostics inline), but CMake's own __run_co_compile wrapper does not propagate the launched
+# tool's exit code to the build, so IWYU's own "-Xiwyu --error" cannot fail that step (verified: a
+# deliberately-unused #include in a header still lets `cmake --build` finish with exit code 0).
+# iwyu_tool.py, which ships with IWYU, reads compile_commands.json and does return a non-zero exit
+# code for any analyzed file with findings; ci_single_binaries uses it to actually fail on findings.
+find_program(IWYU_TOOL_PY NAMES iwyu_tool iwyu_tool.py iwyu-tool)
+
 find_program(INFER_TOOL NAMES infer)
 execute_process(COMMAND ${INFER_TOOL} --version OUTPUT_VARIABLE INFER_TOOL_VERSION ERROR_VARIABLE INFER_TOOL_VERSION)
 string(REGEX MATCH "[0-9]+(\\.[0-9]+)+" INFER_TOOL_VERSION "${INFER_TOOL_VERSION}")
@@ -55,12 +63,6 @@ execute_process(COMMAND ${NINJA_TOOL} --version OUTPUT_VARIABLE NINJA_TOOL_VERSI
 string(REGEX MATCH "[0-9]+(\\.[0-9]+)+" NINJA_TOOL_VERSION "${NINJA_TOOL_VERSION}")
 message(STATUS "🔖 Ninja ${NINJA_TOOL_VERSION} (${NINJA_TOOL})")

-find_program(OCLINT_TOOL NAMES oclint-json-compilation-database)
-find_program(OCLINT_VERSION_TOOL NAMES oclint)
-execute_process(COMMAND ${OCLINT_VERSION_TOOL} --version OUTPUT_VARIABLE OCLINT_TOOL_VERSION ERROR_VARIABLE OCLINT_TOOL_VERSION)
-string(REGEX MATCH "[0-9]+(\\.[0-9]+)+" OCLINT_TOOL_VERSION "${OCLINT_TOOL_VERSION}")
-message(STATUS "🔖 OCLint ${OCLINT_TOOL_VERSION} (${OCLINT_TOOL})")
-
 find_program(VALGRIND_TOOL NAMES valgrind)
 execute_process(COMMAND ${VALGRIND_TOOL} --version OUTPUT_VARIABLE VALGRIND_TOOL_VERSION ERROR_VARIABLE VALGRIND_TOOL_VERSION)
 string(REGEX MATCH "[0-9]+(\\.[0-9]+)+" VALGRIND_TOOL_VERSION "${VALGRIND_TOOL_VERSION}")
@@ -128,16 +130,16 @@ foreach(CXX_STANDARD 11 14 17 20 23 26)
        COMMENT "Compile and test with Clang for C++${CXX_STANDARD}"
    )

+    # pass -stdlib=libc++ through CXXFLAGS: an explicit -DCMAKE_CXX_FLAGS would make CMake ignore CXXFLAGS
    add_custom_target(ci_test_clang_libcxx_cxx${CXX_STANDARD}
-        COMMAND CXX=${CLANG_TOOL} CXXFLAGS="${CLANG_CXXFLAGS}" ${CMAKE_COMMAND}
+        COMMAND CXX=${CLANG_TOOL} CXXFLAGS="${CLANG_CXXFLAGS};-stdlib=libc++" ${CMAKE_COMMAND}
            -DCMAKE_BUILD_TYPE=Debug -GNinja
            -DJSON_BuildTests=ON -DJSON_FastTests=ON
            -DJSON_TestStandards=${CXX_STANDARD}
-            -DCMAKE_CXX_FLAGS="-stdlib=libc++"
            -DCMAKE_EXE_LINKER_FLAGS="-lc++abi"
-            -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_clang_cxx${CXX_STANDARD}
-        COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_clang_cxx${CXX_STANDARD}
-        COMMAND cd ${PROJECT_BINARY_DIR}/build_clang_cxx${CXX_STANDARD} && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
+            -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_clang_libcxx_cxx${CXX_STANDARD}
+        COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_clang_libcxx_cxx${CXX_STANDARD}
+        COMMAND cd ${PROJECT_BINARY_DIR}/build_clang_libcxx_cxx${CXX_STANDARD} && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
        COMMENT "Compile and test with Clang for C++${CXX_STANDARD} (libc++)"
    )
 endforeach()
@@ -276,6 +278,20 @@ add_custom_target(ci_test_disableenumserialization
    COMMENT "Compile and test with enum serialization disabled"
 )

+###############################################################################
+# Disable conversion from a one-element tuple of a JSON reference.
+###############################################################################
+
+add_custom_target(ci_test_disabletuplereferenceconversion
+    COMMAND ${CMAKE_COMMAND}
+    -DCMAKE_BUILD_TYPE=Debug -GNinja
+    -DJSON_BuildTests=ON -DJSON_FastTests=ON -DJSON_DisableTupleReferenceConversion=ON
+    -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_disabletuplereferenceconversion
+    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_disabletuplereferenceconversion
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_disabletuplereferenceconversion && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
+    COMMENT "Compile and test with tuple reference conversion disabled"
+)
+
 ###############################################################################
 # Skip the multiple-inclusion library version check.
 ###############################################################################
@@ -362,13 +378,20 @@ add_custom_target(ci_test_clang_sanitizer
 # Check if header is amalgamated and sources are properly indented.
 ###############################################################################

+# Same file set as .github/workflows/check_amalgamation.yml, so a direct push to develop/master/release/*
+# (which only this CMake target checks, not the pull_request-only workflow) is held to the same standard.
 file(GLOB_RECURSE INDENT_FILES
-    ${PROJECT_SOURCE_DIR}/include/nlohmann/*.hpp
-        ${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/*.hpp
    ${PROJECT_SOURCE_DIR}/docs/mkdocs/docs/examples/*.cpp
+    ${PROJECT_SOURCE_DIR}/docs/mkdocs/docs/examples/*.cu
+    ${PROJECT_SOURCE_DIR}/include/*.hpp
+    ${PROJECT_SOURCE_DIR}/include/*.cpp
+    ${PROJECT_SOURCE_DIR}/include/*.cu
+    ${PROJECT_SOURCE_DIR}/tests/*.hpp
+    ${PROJECT_SOURCE_DIR}/tests/*.cpp
+    ${PROJECT_SOURCE_DIR}/tests/*.cu
 )
+list(FILTER INDENT_FILES EXCLUDE REGEX "/tests/thirdparty/|/tests/abi/include/nlohmann/")

 set(include_dir ${PROJECT_SOURCE_DIR}/single_include/nlohmann)
 set(tool_dir ${PROJECT_SOURCE_DIR}/tools/amalgamate)
@@ -377,6 +400,7 @@ add_custom_target(ci_test_amalgamation
    COMMAND cp ${include_dir}/json.hpp ${include_dir}/json.hpp~
    COMMAND cp ${include_dir}/json_fwd.hpp ${include_dir}/json_fwd.hpp~
    COMMAND cp ${include_dir}/json_literals.hpp ${include_dir}/json_literals.hpp~
+    COMMAND cp ${PROJECT_SOURCE_DIR}/BUILD.bazel ${PROJECT_SOURCE_DIR}/BUILD.bazel~

    COMMAND ${Python3_EXECUTABLE} -mvenv venv_astyle
    COMMAND venv_astyle/bin/pip3 --quiet install -r ${CMAKE_SOURCE_DIR}/tools/astyle/requirements.txt
@@ -386,16 +410,18 @@ add_custom_target(ci_test_amalgamation
    COMMAND ${Python3_EXECUTABLE} ${tool_dir}/amalgamate.py -c ${tool_dir}/config_json_fwd.json -s .
    COMMAND cp ${PROJECT_SOURCE_DIR}/include/nlohmann/json_literals.hpp ${include_dir}/json_literals.hpp
    COMMAND venv_astyle/bin/astyle --project=tools/astyle/.astylerc --suffix=none ${include_dir}/json.hpp ${include_dir}/json_fwd.hpp
+    COMMAND ${CMAKE_COMMAND} -P ${PROJECT_SOURCE_DIR}/cmake/scripts/gen_bazel_build_file.cmake

    COMMAND diff ${include_dir}/json.hpp~ ${include_dir}/json.hpp
    COMMAND diff ${include_dir}/json_fwd.hpp~ ${include_dir}/json_fwd.hpp
    COMMAND diff ${include_dir}/json_literals.hpp~ ${include_dir}/json_literals.hpp
+    COMMAND diff ${PROJECT_SOURCE_DIR}/BUILD.bazel~ ${PROJECT_SOURCE_DIR}/BUILD.bazel

    COMMAND venv_astyle/bin/astyle --project=tools/astyle/.astylerc --suffix=orig ${INDENT_FILES}
    COMMAND for FILE in `find . -name '*.orig'`\; do false \; done

    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
-    COMMENT "Check amalgamation and indentation"
+    COMMENT "Check amalgamation, formatting, and BUILD.bazel"
 )

 ###############################################################################
@@ -430,14 +456,14 @@ add_custom_target(ci_test_valgrind
 # Check code with Clang Static Analyzer.
 ###############################################################################

-set(CLANG_ANALYZER_CHECKS "fuchsia.HandleChecker,nullability.NullableDereferenced,nullability.NullablePassedToNonnull,nullability.NullableReturnedFromNonnull,optin.cplusplus.UninitializedObject,optin.cplusplus.VirtualCall,optin.mpi.MPI-Checker,optin.osx.OSObjectCStyleCast,optin.osx.cocoa.localizability.EmptyLocalizationContextChecker,optin.osx.cocoa.localizability.NonLocalizedStringChecker,optin.performance.GCDAntipattern,optin.performance.Padding,optin.portability.UnixAPI,security.FloatLoopCounter,security.insecureAPI.DeprecatedOrUnsafeBufferHandling,security.insecureAPI.bcmp,security.insecureAPI.bcopy,security.insecureAPI.bzero,security.insecureAPI.rand,security.insecureAPI.strcpy,valist.CopyToSelf,valist.Uninitialized,valist.Unterminated,webkit.NoUncountedMemberChecker,webkit.RefCntblBaseVirtualDtor,core.CallAndMessage,core.DivideZero,core.NonNullParamChecker,core.NullDereference,core.StackAddressEscape,core.UndefinedBinaryOperatorResult,core.VLASize,core.uninitialized.ArraySubscript,core.uninitialized.Assign,core.uninitialized.Branch,core.uninitialized.CapturedBlockVariable,core.uninitialized.UndefReturn,cplusplus.InnerPointer,cplusplus.Move,cplusplus.NewDelete,cplusplus.NewDeleteLeaks,cplusplus.PlacementNew,cplusplus.PureVirtualCall,deadcode.DeadStores,nullability.NullPassedToNonnull,nullability.NullReturnedFromNonnull,osx.API,osx.MIG,osx.NumberObjectConversion,osx.OSObjectRetainCount,osx.ObjCProperty,osx.SecKeychainAPI,osx.cocoa.AtSync,osx.cocoa.AutoreleaseWrite,osx.cocoa.ClassRelease,osx.cocoa.Dealloc,osx.cocoa.IncompatibleMethodTypes,osx.cocoa.Loops,osx.cocoa.MissingSuperCall,osx.cocoa.NSAutoreleasePool,osx.cocoa.NSError,osx.cocoa.NilArg,osx.cocoa.NonNilReturnValue,osx.cocoa.ObjCGenerics,osx.cocoa.RetainCount,osx.cocoa.RunLoopAutoreleaseLeak,osx.cocoa.SelfInit,osx.cocoa.SuperDealloc,osx.cocoa.UnusedIvars,osx.cocoa.VariadicMethodTypes,osx.coreFoundation.CFError,osx.coreFoundation.CFNumber,osx.coreFoundation.CFRetainRelease,osx.coreFoundation.containers.OutOfBounds,osx.coreFoundation.containers.PointerSizedValues,security.insecureAPI.UncheckedReturn,security.insecureAPI.decodeValueOfObjCType,security.insecureAPI.getpw,security.insecureAPI.gets,security.insecureAPI.mkstemp,security.insecureAPI.mktemp,security.insecureAPI.vfork,unix.API,unix.Malloc,unix.MallocSizeof,unix.MismatchedDeallocator,unix.Vfork,unix.cstring.BadSizeArg,unix.cstring.NullArg")
+set(CLANG_ANALYZER_CHECKS "nullability.NullableDereferenced,nullability.NullablePassedToNonnull,nullability.NullableReturnedFromNonnull,optin.cplusplus.UninitializedObject,optin.cplusplus.VirtualCall,optin.performance.Padding,optin.portability.UnixAPI,security.FloatLoopCounter,security.insecureAPI.DeprecatedOrUnsafeBufferHandling,security.insecureAPI.bcmp,security.insecureAPI.bcopy,security.insecureAPI.bzero,security.insecureAPI.rand,security.insecureAPI.strcpy,valist.CopyToSelf,valist.Uninitialized,valist.Unterminated,core.CallAndMessage,core.DivideZero,core.NonNullParamChecker,core.NullDereference,core.StackAddressEscape,core.UndefinedBinaryOperatorResult,core.VLASize,core.uninitialized.ArraySubscript,core.uninitialized.Assign,core.uninitialized.Branch,core.uninitialized.CapturedBlockVariable,core.uninitialized.UndefReturn,cplusplus.InnerPointer,cplusplus.Move,cplusplus.NewDelete,cplusplus.NewDeleteLeaks,cplusplus.PlacementNew,cplusplus.PureVirtualCall,deadcode.DeadStores,nullability.NullPassedToNonnull,nullability.NullReturnedFromNonnull,security.insecureAPI.UncheckedReturn,security.insecureAPI.decodeValueOfObjCType,security.insecureAPI.getpw,security.insecureAPI.gets,security.insecureAPI.mkstemp,security.insecureAPI.mktemp,security.insecureAPI.vfork,unix.API,unix.Malloc,unix.MallocSizeof,unix.MismatchedDeallocator,unix.Vfork,unix.cstring.BadSizeArg,unix.cstring.NullArg")

 add_custom_target(ci_clang_analyze
    COMMAND CXX=${CLANG_TOOL} ${CMAKE_COMMAND}
        -DCMAKE_BUILD_TYPE=Debug -GNinja
        -DJSON_BuildTests=ON
        -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_clang_analyze
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_clang_analyze && ${SCAN_BUILD_TOOL} -enable-checker ${CLANG_ANALYZER_CHECKS} --use-c++=${CLANG_TOOL} -analyze-headers -o ${PROJECT_BINARY_DIR}/report ninja
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_clang_analyze && ${SCAN_BUILD_TOOL} -enable-checker ${CLANG_ANALYZER_CHECKS} --use-c++=${CLANG_TOOL} --use-analyzer=${CLANG_TOOL} -analyze-headers --status-bugs -o ${PROJECT_BINARY_DIR}/report ninja
    COMMENT "Check code with Clang Analyzer"
 )

@@ -453,7 +479,7 @@ add_custom_target(ci_cppcheck
    COMMAND venv_cppcheck/bin/cppcheck --enable=warning --check-level=exhaustive --inline-suppr --inconclusive --force
            --std=c++11 ${PROJECT_SOURCE_DIR}/include/nlohmann/json.hpp -I ${CMAKE_SOURCE_DIR}/include
            --error-exitcode=1 --relative-paths=${PROJECT_SOURCE_DIR} -j ${N} --include=default_defines.hpp
-            --cppcheck-build-dir=cppcheck --check-level=exhaustive
+            --cppcheck-build-dir=cppcheck
            -UJSON_CATCH_USER -UJSON_TRY_USER -UJSON_ASSERT -UJSON_INTERNAL_CATCH -UJSON_THROW
            -DJSON_HAS_CPP_11 -UJSON_HAS_CPP_14 -UJSON_HAS_CPP_17 -UJSON_HAS_CPP_20 -UJSON_HAS_THREE_WAY_COMPARISON
    COMMENT "Check code with Cppcheck"
@@ -471,34 +497,6 @@ add_custom_target(ci_cpplint
    WORKING_DIRECTORY ${PROJECT_BINARY_DIR}
 )

-###############################################################################
-# Check code with OCLint.
-###############################################################################
-
-file(COPY ${PROJECT_SOURCE_DIR}/single_include/nlohmann/json.hpp DESTINATION ${PROJECT_BINARY_DIR}/src_single)
-file(RENAME ${PROJECT_BINARY_DIR}/src_single/json.hpp ${PROJECT_BINARY_DIR}/src_single/all.cpp)
-file(APPEND "${PROJECT_BINARY_DIR}/src_single/all.cpp" "\n\nint main()\n{}\n")
-
-add_executable(single_all ${PROJECT_BINARY_DIR}/src_single/all.cpp)
-target_compile_features(single_all PRIVATE cxx_std_11)
-
-add_custom_target(ci_oclint
-    COMMAND ${CMAKE_COMMAND}
-        -DCMAKE_BUILD_TYPE=Debug
-        -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
-        -DJSON_BuildTests=OFF -DJSON_CI=ON
-        -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_oclint
-    COMMAND ${OCLINT_TOOL} -i ${PROJECT_BINARY_DIR}/build_oclint/src_single/all.cpp -p ${PROJECT_BINARY_DIR}/build_oclint --
-        -report-type html -enable-global-analysis --max-priority-1=0 --max-priority-2=1000 --max-priority-3=2000
-        --disable-rule=MultipleUnaryOperator
-        --disable-rule=DoubleNegative
-        --disable-rule=ShortVariableName
-        --disable-rule=GotoStatement
-        --disable-rule=LongLine
-        -o ${PROJECT_BINARY_DIR}/build_oclint/oclint_report.html
-    COMMENT "Check code with OCLint"
-)
-
 ###############################################################################
 # Check code with Clang-Tidy.
 ###############################################################################
@@ -513,29 +511,16 @@ add_custom_target(ci_clang_tidy
    COMMENT "Check code with Clang-Tidy"
 )

-###############################################################################
-# Check code with PVS-Studio Analyzer <https://www.viva64.com/en/pvs-studio/>.
-###############################################################################
-
-add_custom_target(ci_pvs_studio
-    COMMAND CXX=${CLANG_TOOL} ${CMAKE_COMMAND}
-        -DCMAKE_BUILD_TYPE=Debug
-        -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
-        -DJSON_BuildTests=ON
-        -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_pvs_studio
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_pvs_studio && ${PVS_STUDIO_ANALYZER_TOOL} analyze -j 10
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_pvs_studio && ${PLOG_CONVERTER_TOOL} -a'GA:1,2;64:1;CS' -t fullhtml PVS-Studio.log -o pvs
-    COMMENT "Check code with PVS Studio"
-)
-
 ###############################################################################
 # Check code with Infer <https://fbinfer.com> static analyzer.
 ###############################################################################

+# .inferconfig (repository root) pins --fail-on-issue and the currently-triaged issue types that
+# are disabled until they are addressed separately; see #5715 item 4b.
 add_custom_target(ci_infer
    COMMAND mkdir -p ${PROJECT_BINARY_DIR}/build_infer
    COMMAND cd ${PROJECT_BINARY_DIR}/build_infer && ${INFER_TOOL} compile -- ${CMAKE_COMMAND} -DCMAKE_BUILD_TYPE=Debug ${PROJECT_SOURCE_DIR} -DJSON_BuildTests=ON
-    COMMAND cd ${PROJECT_BINARY_DIR}/build_infer && ${INFER_TOOL} run -- make
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_infer && ${INFER_TOOL} run --project-root ${PROJECT_SOURCE_DIR} -- make
    COMMENT "Check code with Infer"
 )

@@ -591,7 +576,13 @@ add_custom_target(ci_reproducible_tests
 # be compiled individually.
 ###############################################################################

-set(iwyu_path_and_options ${IWYU_TOOL} -Xiwyu --max_line_length=300)
+set(iwyu_options -Xiwyu --error -Xiwyu --max_line_length=300)
+set(iwyu_path_and_options ${IWYU_TOOL} ${iwyu_options})
+
+# CMake needs to know the exact flags used to compile each src_single/*.cpp below to hand them to
+# iwyu_tool.py; JSON_CI already implies a from-scratch configure, so enabling this project-wide has
+# no downside here.
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

 foreach(SRC_FILE ${SRC_FILES})
    # get relative path of the header file
@@ -606,14 +597,34 @@ foreach(SRC_FILE ${SRC_FILES})
    target_include_directories(single_${RELATIVE_SRC_FILE} PRIVATE ${PROJECT_SOURCE_DIR}/include)
    target_compile_features(single_${RELATIVE_SRC_FILE} PRIVATE cxx_std_11)
    set_property(TARGET single_${RELATIVE_SRC_FILE} PROPERTY CXX_INCLUDE_WHAT_YOU_USE "${iwyu_path_and_options}")
-    # remember binary for ci_single_binaries target
+    # remember binary for ci_single_binaries
    list(APPEND single_binaries single_${RELATIVE_SRC_FILE})
+    # json.hpp pulls together the whole library behind heavily templated, SFINAE-based code, and
+    # IWYU's suggestion for its one truly ambiguous symbol (a container-comparison "swap,
+    # operator!=") is not deterministic between runs (observed <set>, <unordered_map>, and <map>
+    # for the exact same source across otherwise-identical local and containerized builds). Keep
+    # reporting its diagnostics (informational, via CXX_INCLUDE_WHAT_YOU_USE above) but exclude it
+    # from the hard gate below so a fresh IWYU/compiler combination does not fail this target on a
+    # nondeterministic suggestion for a header that already re-exports everything on purpose.
+    if(NOT RELATIVE_SRC_FILE STREQUAL "json")
+        list(APPEND single_binaries_tus src_single/${RELATIVE_SRC_FILE}.cpp)
+    endif()
 endforeach()

-add_custom_target(ci_single_binaries
+if(IWYU_TOOL_PY)
+    add_custom_target(ci_single_binaries
+        DEPENDS ${single_binaries}
+        COMMAND ${IWYU_TOOL_PY} -p ${PROJECT_BINARY_DIR} ${single_binaries_tus} -- ${iwyu_options}
+        COMMENT "Check if headers are self-contained"
+    )
+else()
+    # iwyu_tool.py (ships with IWYU, e.g. as /usr/bin/iwyu_tool on Debian/Ubuntu) was not found;
+    # fall back to building the self-containment check without enforcing the IWYU findings.
+    add_custom_target(ci_single_binaries
        DEPENDS ${single_binaries}
        COMMENT "Check if headers are self-contained"
-)
+    )
+endif()

 ###############################################################################
 # Benchmarks
@@ -635,10 +646,29 @@ add_custom_target(ci_benchmarks
 # we test the project with different CMake versions:
 # - CMake 3.5 (the earliest supported)
 # - CMake 3.31.6 (the latest 3.x release)
-# - CMake 4.0.0 (the latest release)
+# - CMake 4.0.0 (the first 4.x release)
+# - the CMake version running this build (usually the latest release)

 function(ci_get_cmake version var)
    set(${var} ${PROJECT_BINARY_DIR}/cmake-${version}/bin/cmake)
+    if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_HOST_SYSTEM_PROCESSOR MATCHES "^(x86_64|amd64)$")
+        # Kitware publishes a prebuilt Linux x86_64 archive for every release; unpacking it is far
+        # cheaper than compiling all of CMake (including its own test helpers) from source.
+        add_custom_command(
+            OUTPUT ${${var}}
+            COMMAND wget -nc https://github.com/Kitware/CMake/releases/download/v${version}/cmake-${version}-linux-x86_64.tar.gz
+            COMMAND wget -nc https://github.com/Kitware/CMake/releases/download/v${version}/cmake-${version}-SHA-256.txt
+            # verify the archive against Kitware's published SHA-256 sums before unpacking it
+            COMMAND sh -c "grep ' cmake-${version}-linux-x86_64[.]tar[.]gz$' cmake-${version}-SHA-256.txt | sha256sum -c -"
+            COMMAND tar xfz cmake-${version}-linux-x86_64.tar.gz
+            COMMAND rm cmake-${version}-linux-x86_64.tar.gz cmake-${version}-SHA-256.txt
+            COMMAND ${CMAKE_COMMAND} -E rm -rf cmake-${version}
+            COMMAND ${CMAKE_COMMAND} -E rename cmake-${version}-linux-x86_64 cmake-${version}
+            WORKING_DIRECTORY ${PROJECT_BINARY_DIR}
+            COMMENT "Download prebuilt CMake ${version}"
+        )
+    else()
+        # no prebuilt archive for this platform (e.g. macOS or Linux aarch64): build from source
        add_custom_command(
            OUTPUT ${${var}}
            COMMAND wget -nc https://github.com/Kitware/CMake/releases/download/v${version}/cmake-${version}.tar.gz
@@ -648,8 +678,9 @@ function(ci_get_cmake version var)
            COMMAND cmake -S cmake-${version} -B cmake-${version} -DCMAKE_POLICY_VERSION_MINIMUM=3.5
            COMMAND cmake --build cmake-${version} --parallel 10
            WORKING_DIRECTORY ${PROJECT_BINARY_DIR}
-        COMMENT "Download CMake ${version}"
+            COMMENT "Download and build CMake ${version} from source"
        )
+    endif()
    set(${var} ${${var}} PARENT_SCOPE)
 endfunction()

@@ -659,30 +690,24 @@ ci_get_cmake(4.0.0  CMAKE_4_0_0_BINARY)

 # the tests require CMake 3.13 or later, so they are excluded for CMake 3.5.0
 set(JSON_CMAKE_FLAGS_3_5_0 JSON_Diagnostics JSON_Diagnostic_Positions JSON_GlobalUDLs JSON_ImplicitConversions JSON_DisableEnumSerialization
-    JSON_LegacyDiscardedValueComparison JSON_Install JSON_MultipleHeaders JSON_SystemInclude JSON_Valgrind)
-set(JSON_CMAKE_FLAGS_3_31_6 JSON_BuildTests ${JSON_CMAKE_FLAGS_3_31_6})
+    JSON_LegacyDiscardedValueComparison JSON_Install JSON_MultipleHeaders JSON_SystemInclude JSON_Valgrind
+    JSON_StrictNulHandling)
+set(JSON_CMAKE_FLAGS_3_31_6 JSON_BuildTests ${JSON_CMAKE_FLAGS_3_5_0})
 set(JSON_CMAKE_FLAGS_4_0_0 JSON_BuildTests ${JSON_CMAKE_FLAGS_3_5_0})

 function(ci_add_cmake_flags_targets flag min_version)
    string(TOLOWER "ci_cmake_flag_${flag}" flag_target)
    string(REPLACE . _ min_version_var ${min_version})
    set(cmake_binary ${CMAKE_${min_version_var}_BINARY})
-    add_custom_target(${flag_target}_${min_version}_2
-        COMMENT "Check CMake flag ${flag} (CMake ${CMAKE_VERSION})"
-        COMMAND ${CMAKE_COMMAND}
-            -Werror=dev
-            -D${flag}=ON
-            -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_${flag_target}
-    )
    add_custom_target(${flag_target}_${min_version_var}
-        COMMENT "Check CMake flag ${JSON_CMAKE_FLAG} (CMake ${min_version})"
+        COMMENT "Check CMake flag ${flag} (CMake ${min_version})"
        COMMAND mkdir -pv ${PROJECT_BINARY_DIR}/build_${flag_target}_${min_version_var}
        COMMAND cd ${PROJECT_BINARY_DIR}/build_${flag_target}_${min_version_var}
            && ${cmake_binary} -Werror=dev ${PROJECT_SOURCE_DIR} -D${flag}=ON
        DEPENDS ${cmake_binary}
    )
-    list(APPEND JSON_CMAKE_FLAG_TARGETS ${JSON_CMAKE_FLAG_TARGET} ${flag_target}_${min_version_var})
-    list(APPEND JSON_CMAKE_FLAG_BUILD_DIRS ${PROJECT_BINARY_DIR}/build_${flag_target} ${PROJECT_BINARY_DIR}/build_${flag_target}_${min_version_var})
+    list(APPEND JSON_CMAKE_FLAG_TARGETS ${flag_target}_${min_version_var})
+    list(APPEND JSON_CMAKE_FLAG_BUILD_DIRS ${PROJECT_BINARY_DIR}/build_${flag_target}_${min_version_var})
    set(JSON_CMAKE_FLAG_TARGETS ${JSON_CMAKE_FLAG_TARGETS} PARENT_SCOPE)
    set(JSON_CMAKE_FLAG_BUILD_DIRS ${JSON_CMAKE_FLAG_BUILD_DIRS} PARENT_SCOPE)
 endfunction()
@@ -699,6 +724,20 @@ foreach(JSON_CMAKE_FLAG ${JSON_CMAKE_FLAGS_4_0_0})
    ci_add_cmake_flags_targets(${JSON_CMAKE_FLAG} 4.0.0)
 endforeach()

+# check the same flags with the CMake version running this build
+foreach(JSON_CMAKE_FLAG ${JSON_CMAKE_FLAGS_4_0_0})
+    string(TOLOWER "ci_cmake_flag_${JSON_CMAKE_FLAG}" flag_target)
+    add_custom_target(${flag_target}
+        COMMENT "Check CMake flag ${JSON_CMAKE_FLAG} (CMake ${CMAKE_VERSION})"
+        COMMAND ${CMAKE_COMMAND}
+            -Werror=dev
+            -D${JSON_CMAKE_FLAG}=ON
+            -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_${flag_target}
+    )
+    list(APPEND JSON_CMAKE_FLAG_TARGETS ${flag_target})
+    list(APPEND JSON_CMAKE_FLAG_BUILD_DIRS ${PROJECT_BINARY_DIR}/build_${flag_target})
+endforeach()
+
 add_custom_target(ci_cmake_flags
    DEPENDS ${JSON_CMAKE_FLAG_TARGETS}
    COMMENT "Check CMake flags"
@@ -857,6 +896,6 @@ add_custom_target(ci_test_build_documentation
 ###############################################################################

 add_custom_target(ci_clean
-    COMMAND rm -fr ${PROJECT_BINARY_DIR}/build_* cmake-3.5.0-Darwin64 ${JSON_CMAKE_FLAG_BUILD_DIRS} ${single_binaries}
+    COMMAND rm -fr ${PROJECT_BINARY_DIR}/build_* ${PROJECT_BINARY_DIR}/cmake-3.5.0 ${PROJECT_BINARY_DIR}/cmake-3.31.6 ${PROJECT_BINARY_DIR}/cmake-4.0.0 ${JSON_CMAKE_FLAG_BUILD_DIRS} ${single_binaries}
    COMMENT "Clean generated directories"
 )
@@ -11,20 +11,31 @@ EXAMPLES = $(wildcard mkdocs/docs/examples/*.cpp)

 cxx_standard = $(lastword c++11 $(filter c++%, $(subst ., ,$1)))

+# common compile flags for the stand-alone example files
+EXAMPLE_CPPFLAGS = -I $(SRCDIR) -DJSON_USE_GLOBAL_UDLS=0
+EXAMPLE_WARNFLAGS = -Werror=deprecated-declarations
+
+# examples that document deprecated API and are allowed to use it
+DEPRECATED_EXAMPLES = $(addprefix mkdocs/docs/examples/, \
+	json_pointer__operator__equal_stringtype \
+	json_pointer__operator__notequal_stringtype \
+	json_pointer__operator_string_t)
+$(DEPRECATED_EXAMPLES:=.output) $(DEPRECATED_EXAMPLES:=.test): EXAMPLE_WARNFLAGS = -Wno-deprecated-declarations
+
 # create output from a stand-alone example file
 %.output: %.cpp
-	@echo "standard $(call cxx_standard $(<:.cpp=))"
+	@echo "standard $(call cxx_standard,$(<:.cpp=))"
 	$(MAKE) $(<:.cpp=) \
-		CPPFLAGS="-I $(SRCDIR) -DJSON_USE_GLOBAL_UDLS=0" \
-		CXXFLAGS="-std=$(call cxx_standard,$(<:.cpp=)) -Wno-deprecated-declarations"
+		CPPFLAGS="$(EXAMPLE_CPPFLAGS)" \
+		CXXFLAGS="-std=$(call cxx_standard,$(<:.cpp=)) $(EXAMPLE_WARNFLAGS)"
 	./$(<:.cpp=) > $@
 	rm $(<:.cpp=)

 # compare created output with current output of the example files
 %.test: %.cpp
 	$(MAKE) $(<:.cpp=) \
-		CPPFLAGS="-I $(SRCDIR) -DJSON_USE_GLOBAL_UDLS=0" \
-		CXXFLAGS="-std=$(call cxx_standard,$(<:.cpp=)) -Wno-deprecated-declarations"
+		CPPFLAGS="$(EXAMPLE_CPPFLAGS)" \
+		CXXFLAGS="-std=$(call cxx_standard,$(<:.cpp=)) $(EXAMPLE_WARNFLAGS)"
 	./$(<:.cpp=) > $@
 	diff $@ $(<:.cpp=.output)
 	rm $(<:.cpp=) $@
@@ -13,7 +13,7 @@
    <key>dashIndexFilePath</key>
    <string>index.html</string>
    <key>DashDocSetFallbackURL</key>
-    <string>https://nlohmann.github.io/json/</string>
+    <string>https://json.nlohmann.me/</string>
    <key>isJavaScriptEnabled</key>
    <true/>
 </dict>
@@ -52,35 +52,25 @@ install_docset_zeal: JSON_for_Modern_C++.docset
 	mkdir -p $$docset_root; \
 	cp -r JSON_for_Modern_C++.docset $$docset_root/

+# both targets below compare the docset search index with the mkdocs page
+# set. They share the same normalization (docs/foo/index.md and
+# docs/foo.md both become foo/index.html, the URL mkdocs itself would
+# give the page; the top-level index.md is excluded, as it is not part
+# of the hand-curated docSet.sql) and use comm(1) on two sorted lists
+# instead of running a sqlite3 query, or an O(n*m) nested shell loop,
+# once per page.
+DOCSET_INDEX_PATHS=$(shell sqlite3 docSet.dsidx "SELECT DISTINCT path FROM searchIndex" | sort)
+DOCSET_PAGE_PATHS=$(shell echo '$(MKDOCS_PAGES)' | tr ' ' '\n' | grep -v '^index\.md$$' | $(SED) -E 's@/index\.md$$@/index.html@; s@\.md$$@/index.html@' | sort)
+
 # list mkdocs pages missing from the docset index
 .PHONY: list_missing_pages
 list_missing_pages: docSet.dsidx
-	@for page in $(MKDOCS_PAGES); do \
-		case "$$page" in \
-			*/index.md) path=$${page/\/index.md/} ;; \
-			*)          path=$${page/.md/}        ;; \
-		esac; \
-		if [ "x$$page" != "xindex.md" -a "x$$(sqlite3 docSet.dsidx "SELECT COUNT(*) FROM searchIndex WHERE path='$$path/index.html'")" = "x0" ]; then \
-			echo $$page; \
-		fi \
-	done
+	@comm -23 <(echo '$(DOCSET_PAGE_PATHS)' | tr ' ' '\n') <(echo '$(DOCSET_INDEX_PATHS)' | tr ' ' '\n')

 # list paths in the docset index without a corresponding mkdocs page
 .PHONY: list_removed_paths
 list_removed_paths: docSet.dsidx
-	@for path in $$(sqlite3 docSet.dsidx "SELECT path FROM searchIndex"); do \
-		page=$${path/\/index.html/.md}; \
-		page_index=$${path/index.html/index.md}; \
-		page_found=0; \
-		for p in $(MKDOCS_PAGES); do \
-			if [ "x$$p" = "x$$page" -o "x$$p" = "x$$page_index" ]; then \
-				page_found=1; \
-			fi \
-		done; \
-		if [ "x$$page_found" = "x0" ]; then \
-			echo $$path; \
-		fi \
-	done
+	@comm -13 <(echo '$(DOCSET_PAGE_PATHS)' | tr ' ' '\n') <(echo '$(DOCSET_INDEX_PATHS)' | tr ' ' '\n')

 .PHONY: clean
 clean:
@@ -7,10 +7,11 @@ documentation browsers like [Dash](https://kapeli.com/dash), [Velocity](https://
 The docset can be created with

 ```sh
-make nlohmann_json.docset
+make JSON_for_Modern_C++.docset
 ```

-The generated folder `nlohmann_json.docset` can then be opened in the documentation browser.
+The generated folder `JSON_for_Modern_C++.docset` can then be opened in the documentation browser. `make all` builds a
+`JSON_for_Modern_C++.tgz` archive instead, and `make install_docset_zeal` installs the docset for Zeal directly.

 A recent version is also part of the [Dash user contributions](https://github.com/Kapeli/Dash-User-Contributions/tree/master/docsets/JSON_for_Modern_C%2B%2B).

@@ -210,6 +210,7 @@ INSERT INTO searchIndex(name, type, path) VALUES ('JSON_CATCH_USER', 'Macro', 'a
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_DIAGNOSTICS', 'Macro', 'api/macros/json_diagnostics/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_DIAGNOSTIC_POSITIONS', 'Macro', 'api/macros/json_diagnostic_positions/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_DISABLE_ENUM_SERIALIZATION', 'Macro', 'api/macros/json_disable_enum_serialization/index.html');
+INSERT INTO searchIndex(name, type, path) VALUES ('JSON_DISABLE_TUPLE_REFERENCE_CONVERSION', 'Macro', 'api/macros/json_disable_tuple_reference_conversion/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_HAS_CPP_11', 'Macro', 'api/macros/json_has_cpp_11/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_HAS_CPP_14', 'Macro', 'api/macros/json_has_cpp_11/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('JSON_HAS_CPP_17', 'Macro', 'api/macros/json_has_cpp_11/index.html');
@@ -159,6 +159,8 @@ basic_json(basic_json&& other) noexcept;
    - `CompatibleType` is not `basic_json` (to avoid hijacking copy/move constructors),
    - `CompatibleType` is not a different `basic_json` type (i.e. with different template arguments)
    - `CompatibleType` is not a `basic_json` nested type (e.g., `json_pointer`, `iterator`, etc.)
+    - if [`JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`](../macros/json_disable_tuple_reference_conversion.md) is defined
+      to `1`: `CompatibleType` is not a one-element `std::tuple` holding a reference to `basic_json`
    - `json_serializer<U>` (with `U = uncvref_t<CompatibleType>`) has a `to_json(basic_json_t&, CompatibleType&&)`
       method

@@ -37,6 +37,12 @@ Thereby, `Target` is the current object; that is, the patch is applied to the cu

 Linear in the lengths of `apply_patch`.

+## Notes
+
+`apply_patch` may be `#!cpp *this` itself or refer to a value contained in `#!cpp *this` (for example, a subobject
+returned by `#!cpp (*this)[key]`); it is read as it was when `merge_patch()` was called, before any modification of
+`#!cpp *this`.
+
 ## Examples

 ??? example
@@ -61,3 +67,5 @@ Linear in the lengths of `apply_patch`.
 ## Version history

 - Added in version 3.0.0.
+- Fixed use of freed or relocated memory when `apply_patch` is `#!cpp *this` or refers to a value contained in
+  `#!cpp *this`, in version 3.13.0.
@@ -51,7 +51,7 @@ range will yield over/underflow when used in a constructor. During deserializati
 will automatically be stored as [`number_unsigned_t`](number_unsigned_t.md) or [`number_float_t`](number_float_t.md).

 [RFC 8259](https://tools.ietf.org/html/rfc8259) further states:
-> Note that when such software is used, numbers that are integers and are in the range $[-2^{53}+1, 2^{53}-1]$ are
+> Note that when such software is used, numbers that are integers and are in the range [-2<sup>53</sup>+1, 2<sup>53</sup>-1] are
 > interoperable in the sense that implementations will agree exactly on their numeric values.

 As this range is a subrange of the exactly supported range [INT64_MIN, INT64_MAX], this class's integer type is
@@ -52,7 +52,7 @@ when used in a constructor. During deserialization, too large or small integer n
 as [`number_integer_t`](number_integer_t.md) or [`number_float_t`](number_float_t.md).

 [RFC 8259](https://tools.ietf.org/html/rfc8259) further states:
-> Note that when such software is used, numbers that are integers and are in the range $[-2^{53}+1, 2^{53}-1]$ are
+> Note that when such software is used, numbers that are integers and are in the range [-2<sup>53</sup>+1, 2<sup>53</sup>-1] are
 > interoperable in the sense that implementations will agree exactly on their numeric values.

 As this range is a subrange (when considered in conjunction with the `number_integer_t` type) of the exactly supported
@@ -54,7 +54,7 @@ classDiagram

 ## Notes

-For an input with $n$ bytes, 1 is the index of the first character and $n+1$ is the index of the terminating null byte
+For an input with <i>n</i> bytes, 1 is the index of the first character and <i>n</i>+1 is the index of the terminating null byte
 or the end of file. This also holds true when reading a byte vector for binary formats.

 ## Examples
@@ -59,6 +59,12 @@ Basic guarantee: if an exception is thrown during the operation, the JSON value
 1. O(N*log(size() + N)), where N is the number of elements to insert.
 2. O(N*log(size() + N)), where N is the number of elements to insert.

+## Notes
+
+The argument `j` (or, for overload (2), the range `[first, last)`) may be `#!cpp *this` itself or refer to a value
+contained in `#!cpp *this` (for example, a subobject returned by `#!cpp (*this)[key]`); it is read as it was when
+`update()` was called, before any modification of `#!cpp *this`.
+
 ## Examples

 ??? example
@@ -155,3 +161,5 @@ Basic guarantee: if an exception is thrown during the operation, the JSON value

 - Added in version 3.0.0.
 - Added `merge_objects` parameter in 3.10.5.
+- Fixed use of freed or relocated memory when the argument is `#!cpp *this` or refers to a value contained in
+  `#!cpp *this`, in version 3.13.0.
@@ -53,6 +53,7 @@ header. See also the [macro overview page](../../features/macros.md).

 - [**JSON_BRACE_INIT_COPY_SEMANTICS**](json_brace_init_copy_semantics.md) - opt in to copy/move semantics for single-element brace initialization
 - [**JSON_DISABLE_ENUM_SERIALIZATION**](json_disable_enum_serialization.md) - switch off default serialization/deserialization functions for enums
+- [**JSON_DISABLE_TUPLE_REFERENCE_CONVERSION**](json_disable_tuple_reference_conversion.md) - switch off conversion from a one-element tuple of a JSON reference
 - [**JSON_USE_IMPLICIT_CONVERSIONS**](json_use_implicit_conversions.md) - control implicit conversions

 ## Comparison behavior
@@ -0,0 +1,114 @@
+# JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
+
+```cpp
+#define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION /* value */
+```
+
+When defined to `1`, a `basic_json` value can no longer be constructed from a one-element `std::tuple` whose element is
+a reference to that `basic_json` type, such as `std::tuple<json&>`, `std::tuple<const json&>`, or `std::tuple<json&&>`.
+These are the tuples created by `std::forward_as_tuple(j)`.
+
+## Default definition
+
+The default value is `0` (disabled — existing behavior is preserved).
+
+```cpp
+#define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 0
+```
+
+## Notes
+
+!!! note "Background"
+
+    By default, `basic_json` can be constructed from any `std::tuple` whose elements can be converted to JSON; the result
+    is an array. This includes `std::tuple<json&>`, which becomes a one-element array.
+
+    `std::tuple` only converts another tuple element by element if its element type cannot be constructed from the whole
+    source tuple. Because `json` *can* be constructed from `std::tuple<json&>`, `std::tuple` instead converts the whole
+    tuple into a single `json` value. This has two surprising effects:
+
+    ```cpp
+    json j = true;
+
+    // rejected by some standard libraries (e.g., libc++); with others, the
+    // reference binds to a temporary that is destroyed right away
+    std::tuple<const json&> t1(std::forward_as_tuple(j));
+
+    // compiles, but std::get<0>(t2) is [true], not true
+    std::tuple<json> t2(std::forward_as_tuple(j));
+    ```
+
+    Enabling this macro removes the conversion, so both tuples are converted element by element: `std::get<0>(t1)`
+    refers to `j`, and `std::get<0>(t2)` is a copy of `j` (see [#2226](https://github.com/nlohmann/json/issues/2226)).
+
+!!! warning "Opt-in only"
+
+    This macro must be defined **before** including `<nlohmann/json.hpp>`. Defining it after the include has no effect.
+
+!!! note "Affected conversions"
+
+    Only one-element tuples holding a reference to the **same** `basic_json` type are affected. Constructing a JSON value
+    from them no longer compiles:
+
+    ```cpp
+    json j = true;
+    json a = std::forward_as_tuple(j);  // error with the macro enabled
+    json b = json::array({j});          // use this instead: [true]
+    ```
+
+    Tuples holding a JSON value (`std::make_tuple(j)`), tuples with more than one element, and tuples holding references
+    to other types (including other `basic_json` specializations) are converted to arrays as before.
+
+!!! hint "CMake option"
+
+    This behavior can also be controlled with the CMake option
+    [`JSON_DisableTupleReferenceConversion`](../../integration/cmake.md#json_disabletuplereferenceconversion)
+    (`OFF` by default) which defines `JSON_DISABLE_TUPLE_REFERENCE_CONVERSION` accordingly.
+
+## Examples
+
+??? example "Default behavior (macro not defined)"
+
+    ```cpp
+    #include <nlohmann/json.hpp>
+
+    using json = nlohmann::json;
+
+    int main()
+    {
+        json j = true;
+
+        std::tuple<json> t(std::forward_as_tuple(j));
+        // std::get<0>(t) is [true] -- the whole tuple was converted
+    }
+    ```
+
+??? example "Conversion disabled (macro defined to 1)"
+
+    ```cpp
+    #define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 1
+    #include <nlohmann/json.hpp>
+
+    using json = nlohmann::json;
+
+    int main()
+    {
+        json j = true;
+
+        std::tuple<json> t(std::forward_as_tuple(j));
+        // std::get<0>(t) is true -- a copy of j
+
+        std::tuple<const json&> r(std::forward_as_tuple(j));
+        // std::get<0>(r) refers to j
+    }
+    ```
+
+## See also
+
+- [**basic_json(CompatibleType&&)**](../basic_json/basic_json.md) - the affected constructor
+- [:simple-cmake: JSON_DisableTupleReferenceConversion](../../integration/cmake.md#json_disabletuplereferenceconversion) -
+  CMake option to control the macro
+
+## Version history
+
+- Added in version 3.13.0.
@@ -90,7 +90,7 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
        | GNU 14.2.0                                   | x86_64       | Ubuntu 22.04.1 LTS                | GitHub    |
        | GNU 15.1.0                                   | x86_64       | Ubuntu 22.04.1 LTS                | GitHub    |
        | GNU 16.1.0                                   | x86_64       | Ubuntu 22.04.1 LTS                | GitHub    |
-        | GNU 16.1.0                                   | arm64        | Linux 6.1.100                     | Cirrus CI |
+        | GNU 16.1.0                                   | arm64        | Ubuntu 24.04                      | GitHub    |
        | icpc (ICC) 2021.10.0 20230609                | x86_64       | Ubuntu 22.04 LTS                  | GitHub    |
        | icpx (Intel oneAPI DPC++/C++) 2025.3.2       | x86_64       | Ubuntu 24.04 LTS                  | GitHub    |
        | nvc++ (NVIDIA HPC SDK) 25.5-0                | x86_64       | Ubuntu 22.04 LTS                  | GitHub    |
@@ -132,7 +132,8 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
  [libstdc++](https://gcc.gnu.org/onlinedocs/libstdc++/) to detect subtle differences or incompatibilities.
 - [x] The code checked with [Include What You Use (IWYU)](https://include-what-you-use.org) that all required standard
  headers are included.
- [x] On Windows, the library is compiled with `<Windows.h>` being included to detect and avoid common bugs.
+- [x] On Windows, the library is compiled with `<Windows.h>` being included to detect and avoid common bugs (see
+  [`unit-windows_h.cpp`](https://github.com/nlohmann/json/blob/develop/tests/src/unit-windows_h.cpp)).
 - [x] The library is compiled with exceptions disabled to support alternative means of error handling.

 ## Stable public API
@@ -1 +0,0 @@
-<a target="_blank" href="https://wandbox.org/permlink/hUJYo1HWmfTBLMGn"><b>online</b></a>
@@ -1 +0,0 @@
-<a target="_blank" href="https://wandbox.org/permlink/AWbpa8e1xRV3y4MM"><b>online</b></a>
@@ -61,7 +61,7 @@ The library uses the following mapping from JSON values types to BJData types ac

    The following values can **not** be converted to a BJData value:

-      - strings with more than 18446744073709551615 bytes, i.e., $2^{64}-1$ bytes (theoretical)
+      - strings with more than 18446744073709551615 bytes, i.e., 2<sup>64</sup>-1 bytes (theoretical)

 !!! info "Unused BJData markers"

@@ -83,6 +83,13 @@ When defined, default parse and serialize functions for enums are excluded and h

 See [full documentation of `JSON_DISABLE_ENUM_SERIALIZATION`](../api/macros/json_disable_enum_serialization.md).

+## `JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`
+
+When defined to `1`, a JSON value can no longer be created from a one-element `std::tuple` holding a reference to a JSON
+value, such as the result of `std::forward_as_tuple(j)`. This lets `std::tuple` convert such tuples element-wise.
+
+See [full documentation of `JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`](../api/macros/json_disable_tuple_reference_conversion.md).
+
 ## `JSON_NO_AUTOMATIC_UDLS`

 When defined, `<nlohmann/json.hpp>` does not include `<nlohmann/json_literals.hpp>` with the user-defined string literals
@@ -273,7 +273,7 @@ When the default type is used, the maximal unsigned integer number that can be s

 [RFC 8259](https://tools.ietf.org/html/rfc8259) further states:

-> Note that when such software is used, numbers that are integers and are in the range $[-2^{53}+1, 2^{53}-1]$ are interoperable in the sense that implementations will agree exactly on their numeric values.
+> Note that when such software is used, numbers that are integers and are in the range [-2<sup>53</sup>+1, 2<sup>53</sup>-1] are interoperable in the sense that implementations will agree exactly on their numeric values.

 As this range is a subrange of the exactly supported range [`INT64_MIN`, `INT64_MAX`], this class's integer type is interoperable.

@@ -48,7 +48,7 @@ On number interoperability, the following remarks are made:
    for numeric magnitude and precision than is widely available.
    
    Note that when such software is used, numbers that are integers and
-    are in the range $[-2^{53}+1, 2^{53}-1]$ are interoperable in the
+    are in the range [-2<sup>53</sup>+1, 2<sup>53</sup>-1] are interoperable in the
    sense that implementations will agree exactly on their numeric
    values.

@@ -95,9 +95,9 @@ This is the same behavior as the code `#!c double x = 3.141592653589793238462643

 !!! success "Interoperability"

-    - The library is interoperable with respect to the specification, because its supported range $[-2^{63}, 2^{64}-1]$ is
-      larger than the described range $[-2^{53}+1, 2^{53}-1]$.
-    - All integers outside the range $[-2^{63}, 2^{64}-1]$, as well as floating-point numbers are stored as `double`.
+    - The library is interoperable with respect to the specification, because its supported range [-2<sup>63</sup>, 2<sup>64</sup>-1] is
+      larger than the described range [-2<sup>53</sup>+1, 2<sup>53</sup>-1].
+    - All integers outside the range [-2<sup>63</sup>, 2<sup>64</sup>-1], as well as floating-point numbers are stored as `double`.
      This also concurs with the specification above.

 ### Zeros
@@ -169,6 +169,12 @@ Enable position diagnostics by defining macro [`JSON_DIAGNOSTIC_POSITIONS`](../a
 Disable default `enum` serialization by defining the macro
 [`JSON_DISABLE_ENUM_SERIALIZATION`](../api/macros/json_disable_enum_serialization.md). This option is `OFF` by default.

+### `JSON_DisableTupleReferenceConversion`
+
+Disable the conversion from a one-element `std::tuple` holding a reference to a JSON value by defining the macro
+[`JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`](../api/macros/json_disable_tuple_reference_conversion.md). This option is
+`OFF` by default.
+
 ### `JSON_FastTests`

 Skip expensive/slow test suites. This option is `OFF` by default. Depends on `JSON_BuildTests`.
@@ -678,11 +678,11 @@ to install the [nlohmann-json](https://ports.macports.org/port/nlohmann-json/) p
    1. Create the following files:

        ```cpp title="example.cpp"
-        --8<-- "integration/homebrew/example.cpp"
+        --8<-- "integration/macports/example.cpp"
        ```

        ```cmake title="CMakeLists.txt"
-        --8<-- "integration/homebrew/CMakeLists.txt"
+        --8<-- "integration/macports/CMakeLists.txt"
        ```

    2. Install the package:
@@ -287,6 +287,7 @@ nav:
          - 'JSON_DIAGNOSTICS': api/macros/json_diagnostics.md
          - 'JSON_DIAGNOSTIC_POSITIONS': api/macros/json_diagnostic_positions.md
          - 'JSON_DISABLE_ENUM_SERIALIZATION': api/macros/json_disable_enum_serialization.md
+          - 'JSON_DISABLE_TUPLE_REFERENCE_CONVERSION': api/macros/json_disable_tuple_reference_conversion.md
          - 'JSON_HAS_CPP_11, JSON_HAS_CPP_14, JSON_HAS_CPP_17, JSON_HAS_CPP_20': api/macros/json_has_cpp_11.md
          - 'JSON_HAS_EXPERIMENTAL_FILESYSTEM, JSON_HAS_FILESYSTEM': api/macros/json_has_filesystem.md
          - 'JSON_HAS_RANGES': api/macros/json_has_ranges.md
@@ -350,7 +351,6 @@ markdown_extensions:
  - toc:
      permalink: true
  - md_in_html
-  - pymdownx.arithmatex
  - pymdownx.betterem:
      smart_enable: all
  - pymdownx.caret
@@ -442,6 +442,3 @@ plugins:

 extra_css:
  - css/custom.css
-
-extra_javascript:
-  - https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-MML-AM_CHTML
@@ -79,9 +79,9 @@ def check_structure() -> None:
                    report("whitespace/line_length", f"{file}:{lineno+1} ({current_section})", f"line is too long ({len(line)} vs. 160 chars)")

                # sections in `<!-- NOLINT -->` comments are treated as present
-                if line.startswith("<!-- NOLINT"):
-                    current_section = line.strip("<!-- NOLINT")
-                    current_section = current_section.strip(" -->")
+                nolint_match = re.match(r"<!--\s*NOLINT\s+(.*?)\s*-->", line)
+                if nolint_match:
+                    current_section = nolint_match.group(1)
                    existing_sections.append(current_section)

                # check if sections are correct
@@ -97,7 +97,7 @@ def check_structure() -> None:
                            if len(unexpected):
                                report("style/numbering", f"{file}:{lineno} ({current_section})", f'unexpected overloads: {", ".join([f"({x})" for x in unexpected])}')

-                    current_section = line.strip("## ")
+                    current_section = line[3:]
                    existing_sections.append(current_section)

                    if current_section in expected_sections:
@@ -141,7 +141,7 @@ def check_structure() -> None:
                # check that non-example admonitions have titles
                untitled_admonition = re.match(r"^(\?\?\?|!!!) ([^ ]+)$", line)
                if untitled_admonition and untitled_admonition.group(2) != "example":
-                    report("style/admonition_title", f"{file}:{lineno} ({current_section})", f'"{untitled_admonition.group(2)}" admonitions should have a title')
+                    report("style/admonition_title", f"{file}:{lineno+1} ({current_section})", f'"{untitled_admonition.group(2)}" admonitions should have a title')

                previous_line = line

@@ -471,11 +471,13 @@ inline void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<
    j = { std::get<Idx>(t)... };
 }

-#if JSON_BRACE_INIT_COPY_SEMANTICS
-// JSON_BRACE_INIT_COPY_SEMANTICS makes a one-element braced list copy its
-// element instead of wrapping it, which would serialize std::tuple<int>{5} as 5
-// rather than [5]. Build what the default deduction builds instead: an object
-// if the element is a [string, value] pair, a one-element array otherwise.
+// A one-element braced list does not reliably wrap its element: with
+// JSON_BRACE_INIT_COPY_SEMANTICS it copies it, which would serialize
+// std::tuple<int>{5} as 5 rather than [5], and some compilers (e.g., Apple clang
+// 15 and 16) copy an element that is itself a basic_json even without it, so
+// std::tuple<json>{true} became true rather than [true]. Build what the default
+// deduction builds instead: an object if the element is a [string, value] pair,
+// a one-element array otherwise.
 template<typename BasicJsonType, typename Tuple>
 inline void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<0> /*unused*/)
 {
@@ -493,7 +495,6 @@ inline void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<
        j = BasicJsonType::array({std::move(element)});
    }
 }
-#endif

 template<typename BasicJsonType, typename Tuple>
 inline void to_json_tuple_impl(BasicJsonType& j, const Tuple& /*unused*/, index_sequence<> /*unused*/)
@@ -8,7 +8,6 @@

 #pragma once

-#include <algorithm> // generate_n
 #include <array> // array
 #include <cmath> // ldexp
 #include <cstddef> // size_t
@@ -123,16 +122,16 @@ class binary_reader
    ~binary_reader() = default;

    /*!
-    @param[in] format  the binary format to parse
+    @brief parse in the format the constructor was given
+
    @param[in] sax_    a SAX event processor
    @param[in] strict  whether to expect the input to be consumed completed
    @param[in] tag_handler  how to treat CBOR tags

    @return whether parsing was successful
    */
-    JSON_HEDLEY_NON_NULL(3)
-    bool sax_parse(const input_format_t format,
-                   json_sax_t* sax_,
+    JSON_HEDLEY_NON_NULL(2)
+    bool sax_parse(json_sax_t* sax_,
                   const bool strict = true,
                   const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
    {
@@ -141,14 +140,14 @@ class binary_reader
        bon8_pushback_size = 0;
        bool result = false;

-        switch (format)
+        switch (input_format)
        {
            case input_format_t::bson:
                result = parse_bson_internal();
                break;

            case input_format_t::cbor:
-                result = parse_cbor_internal(true, tag_handler);
+                result = parse_cbor_internal(tag_handler);
                break;

            case input_format_t::msgpack:
@@ -271,6 +270,22 @@ class binary_reader
        return enter_container(/*is_object*/true, len, type_marker);
    }

+    /*!
+    @brief close the innermost open array or object
+
+    Pops the container opened by the matching @ref enter_container call and
+    emits the SAX end event. Every format-specific driver otherwise repeated
+    the same pop-then-dispatch sequence at its own close site.
+
+    @return whether the SAX parser accepted the end event
+    */
+    bool leave_container()
+    {
+        const bool is_object = container_stack.back().is_object;
+        container_stack.pop_back();
+        return is_object ? sax->end_object() : sax->end_array();
+    }
+
    //////////
    // BSON //
    //////////
@@ -355,8 +370,8 @@ class binary_reader
            if (element_type == 0) // end of the innermost document
            {
                // a copy, not a reference: it must stay valid across the
-                // pop_back() below, which destroys the container_stack
-                // element it would otherwise alias
+                // pop_back() inside leave_container() below, which destroys
+                // the container_stack element it would otherwise alias
                const container_frame top = container_stack.back();

                if (JSON_HEDLEY_UNLIKELY(!check_bson_document_size(top.start_position, top.declared_size)))
@@ -364,8 +379,7 @@ class binary_reader
                    return false;
                }

-                container_stack.pop_back();
-                if (JSON_HEDLEY_UNLIKELY(top.is_object ? !sax->end_object() : !sax->end_array()))
+                if (JSON_HEDLEY_UNLIKELY(!leave_container()))
                {
                    return false;
                }
@@ -860,29 +874,13 @@ class binary_reader
                return enter_array(conditional_static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x1Fu));

            case 0x98: // array (one-byte uint8_t for n follows)
-            {
-                std::uint8_t len{};
-                return get_number(input_format_t::cbor, len) && enter_array(static_cast<std::size_t>(len));
-            }
-
            case 0x99: // array (two-byte uint16_t for n follow)
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::cbor, len) && enter_array(static_cast<std::size_t>(len));
-            }
-
            case 0x9A: // array (four-byte uint32_t for n follow)
-            {
-                std::uint32_t len{};
-                std::size_t size{};
-                return get_number(input_format_t::cbor, len) && get_cbor_container_size(len, size, "array") && enter_array(size);
-            }
-
            case 0x9B: // array (eight-byte uint64_t for n follow)
            {
                std::uint64_t len{};
                std::size_t size{};
-                return get_number(input_format_t::cbor, len) && get_cbor_container_size(len, size, "array") && enter_array(size);
+                return get_cbor_argument(len) && get_cbor_container_size(len, size, "array") && enter_array(size);
            }

            case 0x9F: // array (indefinite length)
@@ -916,35 +914,19 @@ class binary_reader
                return enter_object(conditional_static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x1Fu));

            case 0xB8: // map (one-byte uint8_t for n follows)
-            {
-                std::uint8_t len{};
-                return get_number(input_format_t::cbor, len) && enter_object(static_cast<std::size_t>(len));
-            }
-
            case 0xB9: // map (two-byte uint16_t for n follow)
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::cbor, len) && enter_object(static_cast<std::size_t>(len));
-            }
-
            case 0xBA: // map (four-byte uint32_t for n follow)
-            {
-                std::uint32_t len{};
-                std::size_t size{};
-                return get_number(input_format_t::cbor, len) && get_cbor_container_size(len, size, "map") && enter_object(size);
-            }
-
            case 0xBB: // map (eight-byte uint64_t for n follow)
            {
                std::uint64_t len{};
                std::size_t size{};
-                return get_number(input_format_t::cbor, len) && get_cbor_container_size(len, size, "map") && enter_object(size);
+                return get_cbor_argument(len) && get_cbor_container_size(len, size, "map") && enter_object(size);
            }

            case 0xBF: // map (indefinite length)
                return enter_object(detail::unknown_size());

-            case 0xC0: // tagged item
+            case 0xC0: // tagged item (tag value 0-23, in the head itself)
            case 0xC1:
            case 0xC2:
            case 0xC3:
@@ -968,6 +950,22 @@ class binary_reader
            case 0xD5:
            case 0xD6:
            case 0xD7:
+            {
+                if (tag_handler == cbor_tag_handler_t::error)
+                {
+                    auto last_token = get_token_string();
+                    return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read,
+                                            exception_message(input_format_t::cbor, concat("invalid byte: 0x", last_token), "value"), nullptr));
+                }
+
+                // ignore and store: the tag value is already in the head, so
+                // there is nothing left to read here; the tagged value that
+                // follows is read by the loop in parse_cbor_internal() rather
+                // than by recursing here
+                tag_pending = true;
+                return true;
+            }
+
            case 0xD8: // tagged item (1 byte follows)
            case 0xD9: // tagged item (2 bytes follow)
            case 0xDA: // tagged item (4 bytes follow)
@@ -984,48 +982,12 @@ class binary_reader

                    case cbor_tag_handler_t::ignore:
                    {
-                        // ignore binary subtype
-                        switch (current)
-                        {
-                            case 0xD8:
-                            {
-                                std::uint8_t subtype_to_ignore{};
-                                if (!get_number(input_format_t::cbor, subtype_to_ignore))
-                                {
-                                    return false;
-                                }
-                                break;
-                            }
-                            case 0xD9:
-                            {
-                                std::uint16_t subtype_to_ignore{};
-                                if (!get_number(input_format_t::cbor, subtype_to_ignore))
-                                {
-                                    return false;
-                                }
-                                break;
-                            }
-                            case 0xDA:
-                            {
-                                std::uint32_t subtype_to_ignore{};
-                                if (!get_number(input_format_t::cbor, subtype_to_ignore))
-                                {
-                                    return false;
-                                }
-                                break;
-                            }
-                            case 0xDB:
-                            {
+                        // ignore the tag's binary subtype argument
                        std::uint64_t subtype_to_ignore{};
-                                if (!get_number(input_format_t::cbor, subtype_to_ignore))
+                        if (!get_cbor_argument(subtype_to_ignore))
                        {
                            return false;
                        }
-                                break;
-                            }
-                            default:
-                                break;
-                        }
                        // the tagged value follows; it is read by the loop in
                        // parse_cbor_internal() rather than by recursing here
                        tag_pending = true;
@@ -1034,57 +996,15 @@ class binary_reader

                    case cbor_tag_handler_t::store:
                    {
-                        binary_t b;
                        // use binary subtype and store in a binary container
-                        switch (current)
-                        {
-                            case 0xD8:
-                            {
-                                std::uint8_t subtype{};
-                                if (!get_number(input_format_t::cbor, subtype))
-                                {
-                                    return false;
-                                }
-                                b.set_subtype(detail::conditional_static_cast<typename binary_t::subtype_type>(subtype));
-                                break;
-                            }
-                            case 0xD9:
-                            {
-                                std::uint16_t subtype{};
-                                if (!get_number(input_format_t::cbor, subtype))
-                                {
-                                    return false;
-                                }
-                                b.set_subtype(detail::conditional_static_cast<typename binary_t::subtype_type>(subtype));
-                                break;
-                            }
-                            case 0xDA:
-                            {
-                                std::uint32_t subtype{};
-                                if (!get_number(input_format_t::cbor, subtype))
-                                {
-                                    return false;
-                                }
-                                b.set_subtype(detail::conditional_static_cast<typename binary_t::subtype_type>(subtype));
-                                break;
-                            }
-                            case 0xDB:
-                            {
                        std::uint64_t subtype{};
-                                if (!get_number(input_format_t::cbor, subtype))
+                        if (!get_cbor_argument(subtype))
                        {
                            return false;
                        }
+                        binary_t b;
                        b.set_subtype(detail::conditional_static_cast<typename binary_t::subtype_type>(subtype));
-                                break;
-                            }
-                            default:
-                            {
-                                // as above, the tagged value is read by the caller
-                                tag_pending = true;
-                                return true;
-                            }
-                        }
+
                        get();
                        // a byte string (the heads accepted by get_cbor_binary) keeps the tag as subtype
                        if ((current >= 0x40 && current <= 0x5B) || current == 0x5F)
@@ -1115,52 +1035,7 @@ class binary_reader
                return sax->null();

            case 0xF9: // Half-Precision Float (two-byte IEEE 754)
-            {
-                const auto byte1_raw = get();
-                if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::cbor, "number")))
-                {
-                    return false;
-                }
-                const auto byte2_raw = get();
-                if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::cbor, "number")))
-                {
-                    return false;
-                }
-
-                const auto byte1 = static_cast<unsigned char>(byte1_raw);
-                const auto byte2 = static_cast<unsigned char>(byte2_raw);
-
-                // Code from RFC 8949, Appendix D, Figure 3:
-                // As half-precision floating-point numbers were only added
-                // to IEEE 754 in 2008, today's programming platforms often
-                // still only have limited support for them. It is very
-                // easy to include at least decoding support for them even
-                // without such support. An example of a small decoder for
-                // half-precision floating-point numbers in the C language
-                // is shown in Fig. 3.
-                const auto half = static_cast<unsigned int>((byte1 << 8u) + byte2);
-                const double val = [&half]
-                {
-                    const int exp = (half >> 10u) & 0x1Fu;
-                    const unsigned int mant = half & 0x3FFu;
-                    JSON_ASSERT(exp <= 31);
-                    JSON_ASSERT(mant <= 1023);
-                    switch (exp)
-                    {
-                        case 0:
-                            return std::ldexp(mant, -24);
-                        case 31:
-                            return (mant == 0)
-                            ? std::numeric_limits<double>::infinity()
-                            : std::numeric_limits<double>::quiet_NaN();
-                        default:
-                            return std::ldexp(mant + 1024, exp - 25);
-                    }
-                }();
-                return sax->number_float((half & 0x8000u) != 0
-                                         ? static_cast<number_float_t>(-val)
-                                         : static_cast<number_float_t>(val), "");
-            }
+                return get_half_float(input_format_t::cbor, false);

            case 0xFA: // Single-Precision Float (four-byte IEEE 754)
            {
@@ -1539,6 +1414,73 @@ class binary_reader
        }
    }

+    /*!
+    @brief read a CBOR argument (additional information 24-27) of the width
+           @ref current announces
+
+    The lower 5 bits of @a current (0x18-0x1B) select a 1/2/4/8-byte
+    big-endian unsigned integer that follows the head byte; this is shared by
+    every major type that uses this encoding (unsigned/negative integers,
+    strings, arrays, maps, tags). Reading always goes through @ref get_number,
+    so EOF is reported the same way as before this helper existed.
+
+    @param[out] value  the decoded argument
+    @return whether reading succeeded
+    */
+    bool get_cbor_argument(std::uint64_t& value)
+    {
+        switch (current & 0x1F)
+        {
+            case 0x18: // 1 byte
+            {
+                std::uint8_t n{};
+                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format_t::cbor, n)))
+                {
+                    return false;
+                }
+                value = n;
+                return true;
+            }
+
+            case 0x19: // 2 bytes
+            {
+                std::uint16_t n{};
+                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format_t::cbor, n)))
+                {
+                    return false;
+                }
+                value = n;
+                return true;
+            }
+
+            case 0x1A: // 4 bytes
+            {
+                std::uint32_t n{};
+                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format_t::cbor, n)))
+                {
+                    return false;
+                }
+                value = n;
+                return true;
+            }
+
+            case 0x1B: // 8 bytes
+            {
+                std::uint64_t n{};
+                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format_t::cbor, n)))
+                {
+                    return false;
+                }
+                value = n;
+                return true;
+            }
+
+            default:                 // LCOV_EXCL_LINE
+                JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
+                return false;        // LCOV_EXCL_LINE
+        }
+    }
+
    /*!
    @brief narrow a definite CBOR array/map length to std::size_t

@@ -1571,19 +1513,15 @@ class binary_reader
    enclosing container after each element, so that the nesting depth of the
    input costs heap rather than native stack (see #5104).

-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true) or whether the last read character
-                         @a current should be considered instead
    @param[in] tag_handler how CBOR tags should be treated

    @return whether reading the value succeeded
    */
-    bool parse_cbor_internal(const bool get_char,
-                             const cbor_tag_handler_t tag_handler)
+    bool parse_cbor_internal(const cbor_tag_handler_t tag_handler)
    {
        // whether the next value starts at a fresh byte or at the one already
        // read into `current`
-        bool fetch = get_char;
+        bool fetch = true;

        // the key currently being read; hoisted out of the loop so that its
        // capacity is reused across elements and across nesting levels
@@ -1626,8 +1564,7 @@ class binary_reader

                if (at_end)
                {
-                    container_stack.pop_back();
-                    if (JSON_HEDLEY_UNLIKELY(top.is_object ? !sax->end_object() : !sax->end_array()))
+                    if (JSON_HEDLEY_UNLIKELY(!leave_container()))
                    {
                        return false;
                    }
@@ -1676,9 +1613,6 @@ class binary_reader
    // MsgPack //
    /////////////

-    /*!
-    @return whether a valid MessagePack value was passed to the SAX parser
-    */
    /*!
    @brief read one MessagePack value

@@ -2377,8 +2311,7 @@ class binary_reader

                if (container_stack.back().remaining == 0)
                {
-                    container_stack.pop_back();
-                    if (JSON_HEDLEY_UNLIKELY(is_object ? !sax->end_object() : !sax->end_array()))
+                    if (JSON_HEDLEY_UNLIKELY(!leave_container()))
                    {
                        return false;
                    }
@@ -2423,20 +2356,16 @@ class binary_reader
    ////////////

    /*!
-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true, default) or whether the last read
-                         character should be considered instead
-
    @return whether a valid UBJSON value was passed to the SAX parser
    */
-    bool parse_ubjson_internal(const bool get_char = true)
+    bool parse_ubjson_internal()
    {
        // the key currently being read; hoisted out of the loop so that its
        // capacity is reused across elements and across nesting levels
        string_t key;

        // the type marker of the value to read next
-        char_int_type prefix = get_char ? get_ignore_noop() : current;
+        char_int_type prefix = get_ignore_noop();

        while (true)
        {
@@ -2511,8 +2440,7 @@ class binary_reader
                    break;
                }

-                container_stack.pop_back();
-                if (JSON_HEDLEY_UNLIKELY(top.is_object ? !sax->end_object() : !sax->end_array()))
+                if (JSON_HEDLEY_UNLIKELY(!leave_container()))
                {
                    return false;
                }
@@ -2720,6 +2648,42 @@ class binary_reader
        return true;
    }

+    /*!
+    @brief read a UBJSON/BJData optimized-container count of a signed marker
+           type ('i', 'I', 'l', 'L') and narrow it to std::size_t
+
+    Every signed count marker rejects a negative value the same way (error
+    113); the value_in_range_of check additionally needed for 'L' is only
+    ever live when @a SignedType is std::int64_t on a target where
+    std::size_t is narrower (e.g. 32-bit), since 'i'/'I'/'l' can never exceed
+    std::size_t there.
+
+    @tparam SignedType  std::int8_t, std::int16_t, std::int32_t or std::int64_t
+    @param[out] result  the count narrowed to std::size_t
+    @return whether reading and validating succeeded
+    */
+    template<typename SignedType>
+    bool get_ubjson_signed_count(std::size_t& result)
+    {
+        SignedType number{};
+        if (JSON_HEDLEY_UNLIKELY(!get_number(input_format, number)))
+        {
+            return false;
+        }
+        if (JSON_HEDLEY_UNLIKELY(number < 0))
+        {
+            return sax->parse_error(chars_read, get_token_string(), parse_error::create(113, chars_read,
+                                    exception_message(input_format, "count in an optimized container must be positive", "size"), nullptr));
+        }
+        if (JSON_HEDLEY_UNLIKELY(!value_in_range_of<std::size_t>(number)))
+        {
+            return sax->parse_error(chars_read, get_token_string(), out_of_range::create(408,
+                                    exception_message(input_format, "integer value overflow", "size"), nullptr));
+        }
+        result = static_cast<std::size_t>(number); // NOLINT(bugprone-signed-char-misuse,cert-str34-c): number is not a char
+        return true;
+    }
+
    /*!
    @param[out] result  determined size
    @param[in,out] is_ndarray  for input, `true` means already inside an ndarray vector
@@ -2752,73 +2716,16 @@ class binary_reader
            }

            case 'i':
-            {
-                std::int8_t number{};
-                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format, number)))
-                {
-                    return false;
-                }
-                if (number < 0)
-                {
-                    return sax->parse_error(chars_read, get_token_string(), parse_error::create(113, chars_read,
-                                            exception_message(input_format, "count in an optimized container must be positive", "size"), nullptr));
-                }
-                result = static_cast<std::size_t>(number); // NOLINT(bugprone-signed-char-misuse,cert-str34-c): number is not a char
-                return true;
-            }
+                return get_ubjson_signed_count<std::int8_t>(result);

            case 'I':
-            {
-                std::int16_t number{};
-                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format, number)))
-                {
-                    return false;
-                }
-                if (number < 0)
-                {
-                    return sax->parse_error(chars_read, get_token_string(), parse_error::create(113, chars_read,
-                                            exception_message(input_format, "count in an optimized container must be positive", "size"), nullptr));
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
+                return get_ubjson_signed_count<std::int16_t>(result);

            case 'l':
-            {
-                std::int32_t number{};
-                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format, number)))
-                {
-                    return false;
-                }
-                if (number < 0)
-                {
-                    return sax->parse_error(chars_read, get_token_string(), parse_error::create(113, chars_read,
-                                            exception_message(input_format, "count in an optimized container must be positive", "size"), nullptr));
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
+                return get_ubjson_signed_count<std::int32_t>(result);

            case 'L':
-            {
-                std::int64_t number{};
-                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format, number)))
-                {
-                    return false;
-                }
-                if (number < 0)
-                {
-                    return sax->parse_error(chars_read, get_token_string(), parse_error::create(113, chars_read,
-                                            exception_message(input_format, "count in an optimized container must be positive", "size"), nullptr));
-                }
-                if (!value_in_range_of<std::size_t>(number))
-                {
-                    return sax->parse_error(chars_read, get_token_string(), out_of_range::create(408,
-                                            exception_message(input_format, "integer value overflow", "size"), nullptr));
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
+                return get_ubjson_signed_count<std::int64_t>(result);

            case 'u':
            {
@@ -2909,16 +2816,23 @@ class binary_reader
                    result = 1;
                    for (auto i : dim)
                    {
-                        // Pre-multiplication overflow check: if i > 0 and result > SIZE_MAX/i, then result*i would overflow.
-                        // This check must happen before multiplication since overflow detection after the fact is unreliable
-                        // as modular arithmetic can produce any value, not just 0 or SIZE_MAX.
-                        if (JSON_HEDLEY_UNLIKELY(i > 0 && result > (std::numeric_limits<std::size_t>::max)() / i))
+                        // Pre-multiplication overflow check: since the loop above
+                        // already rejected any zero dimension, i is always > 0
+                        // here, so result > SIZE_MAX/i means result*i would
+                        // overflow. This check must happen before multiplication
+                        // since overflow detection after the fact is unreliable,
+                        // as modular arithmetic can produce any value, not just 0
+                        // or SIZE_MAX.
+                        if (JSON_HEDLEY_UNLIKELY(result > (std::numeric_limits<std::size_t>::max)() / i))
                        {
                            return sax->parse_error(chars_read, get_token_string(), out_of_range::create(408, exception_message(input_format, "excessive ndarray size caused overflow", "size"), nullptr));
                        }
                        result *= i;
-                        // Additional post-multiplication check to catch any edge cases the pre-check might miss
-                        if (result == 0 || result == npos)
+                        // the pre-check above already rules out result becoming 0
+                        // by overflow; the only value it cannot rule out is an
+                        // exact match with npos, the sentinel reserved for an
+                        // unknown-size container (see get_ubjson_size_type())
+                        if (result == npos)
                        {
                            return sax->parse_error(chars_read, get_token_string(), out_of_range::create(408, exception_message(input_format, "excessive ndarray size caused overflow", "size"), nullptr));
                        }
@@ -2979,7 +2893,7 @@ class binary_reader
        {
            result.second = get();  // must not ignore 'N', because 'N' maybe the type
            if (input_format == input_format_t::bjdata
-                    && JSON_HEDLEY_UNLIKELY(std::binary_search(bjd_optimized_type_markers.begin(), bjd_optimized_type_markers.end(), result.second)))
+                    && JSON_HEDLEY_UNLIKELY(is_bjd_excluded_optimized_type(result.second)))
            {
                auto last_token = get_token_string();
                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read,
@@ -3123,50 +3037,7 @@ class binary_reader
                {
                    break;
                }
-                const auto byte1_raw = get();
-                if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format, "number")))
-                {
-                    return false;
-                }
-                const auto byte2_raw = get();
-                if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format, "number")))
-                {
-                    return false;
-                }
-
-                const auto byte1 = static_cast<unsigned char>(byte1_raw);
-                const auto byte2 = static_cast<unsigned char>(byte2_raw);
-
-                // Code from RFC 8949, Appendix D, Figure 3:
-                // As half-precision floating-point numbers were only added
-                // to IEEE 754 in 2008, today's programming platforms often
-                // still only have limited support for them. It is very
-                // easy to include at least decoding support for them even
-                // without such support. An example of a small decoder for
-                // half-precision floating-point numbers in the C language
-                // is shown in Fig. 3.
-                const auto half = static_cast<unsigned int>((byte2 << 8u) + byte1);
-                const double val = [&half]
-                {
-                    const int exp = (half >> 10u) & 0x1Fu;
-                    const unsigned int mant = half & 0x3FFu;
-                    JSON_ASSERT(exp <= 31);
-                    JSON_ASSERT(mant <= 1023);
-                    switch (exp)
-                    {
-                        case 0:
-                            return std::ldexp(mant, -24);
-                        case 31:
-                            return (mant == 0)
-                            ? std::numeric_limits<double>::infinity()
-                            : std::numeric_limits<double>::quiet_NaN();
-                        default:
-                            return std::ldexp(mant + 1024, exp - 25);
-                    }
-                }();
-                return sax->number_float((half & 0x8000u) != 0
-                                         ? static_cast<number_float_t>(-val)
-                                         : static_cast<number_float_t>(val), "");
+                return get_half_float(input_format, true);
            }

            case 'd':
@@ -3239,19 +3110,16 @@ class binary_reader
        if (input_format == input_format_t::bjdata && size_and_type.first != npos && (size_and_type.second & (1 << 8)) != 0)
        {
            size_and_type.second &= ~(static_cast<char_int_type>(1) << 8);  // use bit 8 to indicate ndarray, here we remove the bit to restore the type marker
-            auto it = std::lower_bound(bjd_types_map.begin(), bjd_types_map.end(), size_and_type.second, [](const bjd_type & p, char_int_type t)
-            {
-                return p.first < t;
-            });
+            const char* type_name = bjd_type_name(size_and_type.second);
            string_t key = "_ArrayType_";
-            if (JSON_HEDLEY_UNLIKELY(it == bjd_types_map.end() || it->first != size_and_type.second))
+            if (JSON_HEDLEY_UNLIKELY(type_name == nullptr))
            {
                auto last_token = get_token_string();
                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read,
                                        exception_message(input_format, "invalid byte: 0x" + last_token, "type"), nullptr));
            }

-            string_t type = it->second; // sax->string() takes a reference
+            string_t type = type_name; // sax->string() takes a reference
            if (JSON_HEDLEY_UNLIKELY(!sax->key(key) || !sax->string(type)))
            {
                return false;
@@ -3543,8 +3411,7 @@ class binary_reader

                if (at_end)
                {
-                    container_stack.pop_back();
-                    if (JSON_HEDLEY_UNLIKELY(top.is_object ? !sax->end_object() : !sax->end_array()))
+                    if (JSON_HEDLEY_UNLIKELY(!leave_container()))
                    {
                        return false;
                    }
@@ -4083,6 +3950,68 @@ class binary_reader
        return true;
    }

+    /*!
+    @brief read and decode an IEEE 754 half-precision (16-bit) float
+
+    Used by CBOR (big endian) and BJData (little endian); the two formats
+    only differ in the byte order of the two bytes that make up the half.
+
+    @param[in] format       the current format (for diagnostics)
+    @param[in] little_endian whether the two bytes are little endian (BJData)
+                             or big endian (CBOR)
+
+    @return whether reading and decoding succeeded
+    */
+    bool get_half_float(const input_format_t format, const bool little_endian)
+    {
+        const auto byte1_raw = get();
+        if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(format, "number")))
+        {
+            return false;
+        }
+        const auto byte2_raw = get();
+        if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(format, "number")))
+        {
+            return false;
+        }
+
+        const auto byte1 = static_cast<unsigned char>(byte1_raw);
+        const auto byte2 = static_cast<unsigned char>(byte2_raw);
+
+        // Code from RFC 8949, Appendix D, Figure 3:
+        // As half-precision floating-point numbers were only added
+        // to IEEE 754 in 2008, today's programming platforms often
+        // still only have limited support for them. It is very
+        // easy to include at least decoding support for them even
+        // without such support. An example of a small decoder for
+        // half-precision floating-point numbers in the C language
+        // is shown in Fig. 3.
+        const auto half = little_endian
+                          ? static_cast<unsigned int>((byte2 << 8u) + byte1)
+                          : static_cast<unsigned int>((byte1 << 8u) + byte2);
+        const double val = [&half]
+        {
+            const int exp = (half >> 10u) & 0x1Fu;
+            const unsigned int mant = half & 0x3FFu;
+            JSON_ASSERT(exp <= 31);
+            JSON_ASSERT(mant <= 1023);
+            switch (exp)
+            {
+                case 0:
+                    return std::ldexp(mant, -24);
+                case 31:
+                    return (mant == 0)
+                    ? std::numeric_limits<double>::infinity()
+                    : std::numeric_limits<double>::quiet_NaN();
+                default:
+                    return std::ldexp(mant + 1024, exp - 25);
+            }
+        }();
+        return sax->number_float((half & 0x8000u) != 0
+                                 ? static_cast<number_float_t>(-val)
+                                 : static_cast<number_float_t>(val), "");
+    }
+
    /*!
    @brief create a string by reading characters from the input

@@ -4308,38 +4237,61 @@ class binary_reader
    /// BON8: number of bytes in @ref bon8_pushback
    std::size_t bon8_pushback_size = 0;

-    // excluded markers in bjdata optimized type
-#define JSON_BINARY_READER_MAKE_BJD_OPTIMIZED_TYPE_MARKERS_ \
-    make_array<char_int_type>('F', 'H', 'N', 'S', 'T', 'Z', '[', '{')
-
-#define JSON_BINARY_READER_MAKE_BJD_TYPES_MAP_ \
-    make_array<bjd_type>(                      \
-    bjd_type{'B', "byte"},                     \
-    bjd_type{'C', "char"},                     \
-    bjd_type{'D', "double"},                   \
-    bjd_type{'I', "int16"},                    \
-    bjd_type{'L', "int64"},                    \
-    bjd_type{'M', "uint64"},                   \
-    bjd_type{'U', "uint8"},                    \
-    bjd_type{'d', "single"},                   \
-    bjd_type{'i', "int8"},                     \
-    bjd_type{'l', "int32"},                    \
-    bjd_type{'m', "uint32"},                   \
-    bjd_type{'u', "uint16"})
-
  JSON_PRIVATE_UNLESS_TESTED:
-    // lookup tables
-    // NOLINTNEXTLINE(cppcoreguidelines-non-private-member-variables-in-classes)
-    const decltype(JSON_BINARY_READER_MAKE_BJD_OPTIMIZED_TYPE_MARKERS_) bjd_optimized_type_markers =
-        JSON_BINARY_READER_MAKE_BJD_OPTIMIZED_TYPE_MARKERS_;
+    /*!
+    @brief whether @a marker is excluded from BJData's optimized ND-array types
+    @return whether @a marker is one of 'F', 'H', 'N', 'S', 'T', 'Z', '[', '{'

-    using bjd_type = std::pair<char_int_type, string_t>;
-    // NOLINTNEXTLINE(cppcoreguidelines-non-private-member-variables-in-classes)
-    const decltype(JSON_BINARY_READER_MAKE_BJD_TYPES_MAP_) bjd_types_map =
-        JSON_BINARY_READER_MAKE_BJD_TYPES_MAP_;
+    Mirrors binary_writer's @ref binary_writer::is_bjdata_excluded_type_marker
+    "is_bjdata_excluded_type_marker()`, which encodes the same list the other
+    way; keep the two in sync.
+    */
+    static constexpr bool is_bjd_excluded_optimized_type(const char_int_type marker) noexcept
+    {
+        return marker == '[' || marker == '{' || marker == 'S' || marker == 'H'
+               || marker == 'T' || marker == 'F' || marker == 'N' || marker == 'Z';
+    }

-#undef JSON_BINARY_READER_MAKE_BJD_OPTIMIZED_TYPE_MARKERS_
-#undef JSON_BINARY_READER_MAKE_BJD_TYPES_MAP_
+    /*!
+    @brief look up the ND-array element type name for a BJData dtype marker
+    @return the type name ("uint8", "int8", ...), or nullptr if @a marker does
+            not name a known dtype
+
+    A C++11 `constexpr` function cannot contain a `switch`, so this is a
+    plain (non-constexpr) switch instead.
+    */
+    static const char* bjd_type_name(const char_int_type marker)
+    {
+        switch (marker)
+        {
+            case 'B':
+                return "byte";
+            case 'C':
+                return "char";
+            case 'D':
+                return "double";
+            case 'I':
+                return "int16";
+            case 'L':
+                return "int64";
+            case 'M':
+                return "uint64";
+            case 'U':
+                return "uint8";
+            case 'd':
+                return "single";
+            case 'i':
+                return "int8";
+            case 'l':
+                return "int32";
+            case 'm':
+                return "uint32";
+            case 'u':
+                return "uint16";
+            default:
+                return nullptr;
+        }
+    }
 };

 #ifndef JSON_HAS_CPP_17
@@ -679,29 +679,19 @@ class json_pointer
                        return nullptr;
                    }

-                    // tokens that array_index() rejects with parse_error.106/109
-                    // are passed on to it; all other tokens that it would reject
-                    // with out_of_range.404/410 are detected here, so that this
-                    // also works without exceptions
-                    if (JSON_HEDLEY_UNLIKELY(reference_token.size() > 1 && !(reference_token[0] >= '1' && reference_token[0] <= '9')))
+                    // may throw parse_error.106/109 for a malformed index; an
+                    // index that is syntactically valid but cannot be
+                    // represented (out_of_range.404/410) is treated like an
+                    // out-of-range index below
+                    typename BasicJsonType::size_type idx{};
+                    JSON_TRY
                    {
-                        static_cast<void>(array_index<BasicJsonType>(reference_token)); // throws parse_error.106/109
+                        idx = array_index<BasicJsonType>(reference_token);
                    }
-                    if (JSON_HEDLEY_UNLIKELY(reference_token.empty() || !std::all_of(reference_token.begin(), reference_token.end(), [](const char c)
-                {
-                    return c >= '0' && c <= '9';
-                })))
+                    JSON_INTERNAL_CATCH (detail::out_of_range&)
                    {
                        return nullptr;
                    }
-                    errno = 0; // strtoull() does not reset errno on success
-                    char* p_end = nullptr; // NOLINT(misc-const-correctness)
-                    const unsigned long long magnitude = std::strtoull(reference_token.data(), &p_end, 10); // NOLINT(runtime/int)
-                    if (JSON_HEDLEY_UNLIKELY(errno == ERANGE || magnitude >= static_cast<unsigned long long>((std::numeric_limits<typename BasicJsonType::size_type>::max)()))) // NOLINT(runtime/int)
-                    {
-                        return nullptr;
-                    }
-                    const auto idx = static_cast<typename BasicJsonType::size_type>(magnitude);

                    if (JSON_HEDLEY_UNLIKELY(idx >= ptr->m_data.m_value.array->size()))
                    {
@@ -359,6 +359,7 @@ void templated_json_throw(ExceptionType exception)

 // Macros to simplify conversion from/to types

+// NLOHMANN_JSON_EXPAND to NLOHMANN_JSON_DOUBLE_PASTE63 are generated by tools/macro_builder (see its README.md)
 #define NLOHMANN_JSON_EXPAND( x ) x
 #define NLOHMANN_JSON_GET_MACRO(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, _51, _52, _53, _54, _55, _56, _57, _58, _59, _60, _61, _62, _63, _64, NAME,...) NAME
 #define NLOHMANN_JSON_PASTE(...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \
@@ -621,6 +622,10 @@ void templated_json_throw(ExceptionType exception)
 // arguments, so dispatching on Type,BaseType,member... directly would run out
 // one slot early and cap the derived-type macros at 62 members instead of the
 // 63 that NLOHMANN_JSON_PASTE supports.
+//
+// The slot table below (down to the closing NLOHMANN_JSON_TYPE_BODY_SENTINEL))
+// is generated by tools/macro_builder (see its README.md; run with the
+// "type_body" argument).
 #define NLOHMANN_JSON_TYPE_BODY(Prefix, ...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \
        Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, \
        Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, \
@@ -915,3 +920,7 @@ void templated_json_throw(ExceptionType exception)
 #ifndef JSON_DISABLE_ENUM_SERIALIZATION
    #define JSON_DISABLE_ENUM_SERIALIZATION 0
 #endif
+
+#ifndef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
+    #define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 0
+#endif
@@ -25,6 +25,7 @@
 #undef JSON_INLINE_VARIABLE
 #undef JSON_NO_UNIQUE_ADDRESS
 #undef JSON_DISABLE_ENUM_SERIALIZATION
+#undef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION

 #ifndef JSON_TEST_KEEP_MACROS
    #undef JSON_CATCH
@@ -9,7 +9,6 @@

 #pragma once

-#include <array> // array
 #include <cstddef> // size_t
 #include <type_traits> // conditional, enable_if, false_type, integral_constant, is_constructible, is_integral, is_same, remove_cv, remove_reference, true_type
 #include <utility> // index_sequence, make_index_sequence, index_sequence_for
@@ -161,11 +160,5 @@ struct static_const
    constexpr T static_const<T>::value;
 #endif

-template<typename T, typename... Args>
-constexpr std::array<T, sizeof...(Args)> make_array(Args&& ... args)
-{
-    return std::array<T, sizeof...(Args)> {{static_cast<T>(std::forward<Args>(args))...}};
-}
-
 }  // namespace detail
 NLOHMANN_JSON_NAMESPACE_END
@@ -636,6 +636,18 @@ template<typename BasicJsonType, typename CompatibleType>
 struct is_compatible_type
    : is_compatible_type_impl<BasicJsonType, CompatibleType> {};

+// a one-element std::tuple holding a reference to BasicJsonType, as created by
+// std::forward_as_tuple(j); see JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
+template<typename BasicJsonType, typename T>
+struct is_basic_json_reference_tuple : std::false_type {};
+
+template<typename BasicJsonType, typename T>
+struct is_basic_json_reference_tuple<BasicJsonType, std::tuple<T>>
+{
+    static constexpr bool value =
+        std::is_reference<T>::value && std::is_same<uncvref_t<T>, BasicJsonType>::value;
+};
+
 template<typename BasicJsonType, typename CompatibleArrayType>
 struct is_compatible_binary_type
 {
@@ -29,7 +29,9 @@
 #endif

 #include <algorithm> // all_of, find, for_each, none_of
+#include <cmath> // isnan
 #include <cstddef> // nullptr_t, ptrdiff_t, size_t
+#include <cstdint> // uint8_t
 #include <functional> // hash, less
 #include <initializer_list> // initializer_list
 #ifndef JSON_NO_IO
@@ -38,19 +40,28 @@
 #include <iterator> // make_move_iterator, random_access_iterator_tag
 #include <limits> // numeric_limits
 #include <memory> // unique_ptr
+#include <set> // swap, operator!=
 #include <stdexcept> // length_error
 #include <string> // string, stoi, to_string
+#include <type_traits> // enable_if_t, is_same, is_scalar, ...
+#include <unordered_map> // swap (for the from_json(..., std::unordered_map&) overload)
 #include <utility> // declval, forward, move, pair, swap
 #include <vector> // vector

-#include <nlohmann/adl_serializer.hpp>
+// keep: json.hpp's own basic_json<> default template arguments need the complete definition of
+// each of these, not only the forward declarations from json_fwd.hpp, so IWYU's suggestion to
+// drop them (nothing in this file otherwise names the type) would break every downstream
+// translation unit that relies on basic_json<>'s defaults actually being usable.
+#include <nlohmann/adl_serializer.hpp> // IWYU pragma: keep
 #include <nlohmann/byte_container_with_subtype.hpp>
-#include <nlohmann/detail/conversions/from_json.hpp>
-#include <nlohmann/detail/conversions/to_json.hpp>
+#include <nlohmann/detail/abi_macros.hpp>
+#include <nlohmann/detail/conversions/from_json.hpp> // IWYU pragma: keep
+#include <nlohmann/detail/conversions/to_json.hpp> // IWYU pragma: keep
 #include <nlohmann/detail/exceptions.hpp>
 #include <nlohmann/detail/hash.hpp>
 #include <nlohmann/detail/input/binary_reader.hpp>
 #include <nlohmann/detail/input/input_adapters.hpp>
+#include <nlohmann/detail/input/json_sax.hpp>
 #include <nlohmann/detail/input/lexer.hpp>
 #include <nlohmann/detail/input/parser.hpp>
 #include <nlohmann/detail/iterators/internal_iterator.hpp>
@@ -62,6 +73,7 @@
 #include <nlohmann/detail/json_pointer.hpp>
 #include <nlohmann/detail/json_ref.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
+#include <nlohmann/detail/meta/detected.hpp>
 #include <nlohmann/detail/string_concat.hpp>
 #include <nlohmann/detail/string_escape.hpp>
 #include <nlohmann/detail/string_utils.hpp>
@@ -73,7 +85,8 @@
 #include <nlohmann/detail/recursion_depth_limit.hpp>
 #include <nlohmann/detail/value_t.hpp>
 #include <nlohmann/json_fwd.hpp>
-#include <nlohmann/ordered_map.hpp>
+#include <nlohmann/ordered_map.hpp> // IWYU pragma: keep
+#include <nlohmann/thirdparty/hedley/hedley.hpp>

 #if defined(JSON_HAS_CPP_17)
    #if JSON_HAS_STATIC_RTTI
@@ -906,11 +919,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    /*!
    @brief how many levels the operation going on in this thread has descended into

-    Copying a value and comparing two values share this count. The library never
-    nests one inside the other - copying a value does not compare one, and
-    comparing two values does not copy them - and where user code nests them
-    anyway, sharing the count only ends a descent sooner than it had to, which
-    costs a little speed and is never wrong.
+    Copying a value, converting one from another specialization, and comparing
+    two values share this count. The library never nests one of them inside
+    another - none of them does either of the other two on the way - and where
+    user code nests them anyway, sharing the count only ends a descent sooner
+    than it had to, which costs a little speed and is never wrong.

    A byte is enough: the count never exceeds the limit by more than the single
    level that notices the limit has been reached.
@@ -1267,6 +1280,222 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        copy_iteratively(src);
    }

+    /*!
+    @brief convert the value @a val of another specialization into this null
+           value; @a val must be neither an object nor an array
+
+    Converting such a value never descends, so both ways of converting an
+    object or an array (@ref convert_structured) leave their elements of this
+    kind to the converting constructor, which leaves them to this.
+    */
+    template<typename BasicJsonType>
+    void convert_leaf(const BasicJsonType& val)
+    {
+        using other_boolean_t = typename BasicJsonType::boolean_t;
+        using other_number_float_t = typename BasicJsonType::number_float_t;
+        using other_number_integer_t = typename BasicJsonType::number_integer_t;
+        using other_number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+        using other_string_t = typename BasicJsonType::string_t;
+        using other_binary_t = typename BasicJsonType::binary_t;
+
+        switch (val.type())
+        {
+            case value_t::boolean:
+                JSONSerializer<other_boolean_t>::to_json(*this, val.template get<other_boolean_t>());
+                break;
+            case value_t::number_float:
+                JSONSerializer<other_number_float_t>::to_json(*this, val.template get<other_number_float_t>());
+                break;
+            case value_t::number_integer:
+                JSONSerializer<other_number_integer_t>::to_json(*this, val.template get<other_number_integer_t>());
+                break;
+            case value_t::number_unsigned:
+                JSONSerializer<other_number_unsigned_t>::to_json(*this, val.template get<other_number_unsigned_t>());
+                break;
+            case value_t::string:
+                JSONSerializer<other_string_t>::to_json(*this, val.template get_ref<const other_string_t&>());
+                break;
+            case value_t::binary:
+                JSONSerializer<other_binary_t>::to_json(*this, val.template get_ref<const other_binary_t&>());
+                break;
+            case value_t::null:
+                // m_data.m_type is already value_t::null
+                break;
+            case value_t::discarded:
+                m_data.m_type = value_t::discarded;
+                break;
+            case value_t::object: // LCOV_EXCL_LINE
+            case value_t::array:  // LCOV_EXCL_LINE
+            default:              // LCOV_EXCL_LINE
+                JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
+        }
+    }
+
+    /// scratch space for the converted elements of the arrays that
+    /// @ref convert_iteratively has yet to create
+    using convert_scratch_t = std::vector<basic_json, AllocatorType<basic_json>>;
+
+    /*!
+    @brief create the object or array @a val converted into this null value
+
+    Its converted elements are the last `val.size()` entries of @a elements (an
+    array) or of @a members (an object); they are moved into the container in
+    one go and then removed.
+    */
+    template<typename BasicJsonType>
+    void convert_level(const BasicJsonType& val, convert_scratch_t& elements, copy_scratch_t& members)
+    {
+        if (val.is_object())
+        {
+            const auto first = members.end() - static_cast<typename copy_scratch_t::difference_type>(val.size());
+            m_data.m_value.object = create<object_t>(std::make_move_iterator(first),
+                                    std::make_move_iterator(members.end()));
+            // only now that the object exists may this stop being a null value
+            m_data.m_type = value_t::object;
+            members.erase(first, members.end());
+        }
+        else
+        {
+            const auto first = elements.end() - static_cast<typename convert_scratch_t::difference_type>(val.size());
+            m_data.m_value.array = create<array_t>(std::make_move_iterator(first),
+                                                   std::make_move_iterator(elements.end()));
+            // only now that the array exists may this stop being a null value
+            m_data.m_type = value_t::array;
+            elements.erase(first, elements.end());
+        }
+
+        set_parents();
+    }
+
+    /*!
+    @brief convert the object or array @a val of another specialization into
+           this null value without recursing
+
+    The containers whose conversion has begun are kept on an explicit stack
+    rather than on the call stack. Unlike @ref copy_iteratively, this builds
+    every container from the bottom up: all its elements are converted first,
+    and the container is then created from them in one go, the way the range
+    constructor that converts the levels above the bound does. The two object
+    types need not enumerate their members in the same order, so the members
+    could not be paired up by position anyway, and building from a range keeps
+    what the range constructor does with keys that become equal on conversion.
+
+    Every value is complete before it is handed on, and a container gets its
+    type only once it exists, so whatever throws, every value left behind can
+    be destroyed.
+    */
+    template<typename BasicJsonType>
+    void convert_iteratively(const BasicJsonType& val)
+    {
+        using other_const_iterator = typename BasicJsonType::const_iterator;
+
+        // the containers whose conversion has begun, innermost last, each with
+        // its element to convert next
+        std::vector<std::pair<const BasicJsonType*, other_const_iterator>> pending;
+
+        // the converted elements of the pending arrays and the converted
+        // members of the pending objects, those of the innermost one last
+        convert_scratch_t elements;
+        copy_scratch_t members;
+
+        pending.emplace_back(&val, val.cbegin());
+
+        for (;;)
+        {
+            const BasicJsonType& container = *pending.back().first;
+            // a copy, as descending below can reallocate pending; the
+            // iterator kept in pending is only advanced through pending.back()
+            const other_const_iterator next = pending.back().second;
+
+            if (next != container.cend())
+            {
+                if (next->is_structured())
+                {
+                    // convert its elements first; next stays where it is until
+                    // the converted container is handed back to this one
+                    pending.emplace_back(&*next, next->cbegin());
+                    continue;
+                }
+
+                // the converting constructor does not descend into this value
+                if (container.is_object())
+                {
+                    members.emplace_back(next.key(), *next);
+                }
+                else
+                {
+                    elements.emplace_back(*next);
+                }
+                ++pending.back().second;
+                continue;
+            }
+
+            // all elements of the container are converted: create it
+            pending.pop_back();
+
+            if (pending.empty())
+            {
+                convert_level(container, elements, members);
+                return;
+            }
+
+            basic_json converted;
+            converted.convert_level(container, elements, members);
+#if JSON_DIAGNOSTIC_POSITIONS
+            converted.start_position = container.start_pos();
+            converted.end_position = container.end_pos();
+#endif
+
+            // hand it to the container it is an element of
+            if (pending.back().first->is_object())
+            {
+                members.emplace_back(pending.back().second.key(), std::move(converted));
+            }
+            else
+            {
+                elements.push_back(std::move(converted));
+            }
+            ++pending.back().second;
+        }
+    }
+
+    /*!
+    @brief convert the object or array @a val of another specialization into
+           this null value
+
+    Converting a container converts its elements, so a value nested deeply
+    enough used to exhaust the call stack. The descent is bounded here as in
+    @ref copy_structured: the first `detail::recursion_depth_limit()` levels
+    are converted by the containers' range constructors, just as they always were,
+    and anything below that is converted without the call stack by
+    @ref convert_iteratively.
+
+    @sa https://github.com/nlohmann/json/issues/5650
+    */
+    template<typename BasicJsonType>
+    void convert_structured(const BasicJsonType& val)
+    {
+        const nesting_depth_guard guard;
+
+        if (JSON_HEDLEY_LIKELY(guard.okay()))
+        {
+            // every element comes back to the converting constructor
+            if (val.is_object())
+            {
+                using other_object_t = typename BasicJsonType::object_t;
+                JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
+            }
+            else
+            {
+                using other_array_t = typename BasicJsonType::array_t;
+                JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
+            }
+            return;
+        }
+
+        convert_iteratively(val);
+    }
+

    /// the result of comparing two values, including values that cannot be
    /// ordered at all, such as a discarded value or a NaN
@@ -1596,7 +1825,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    template < typename CompatibleType,
               typename U = detail::uncvref_t<CompatibleType>,
               detail::enable_if_t <
-                   !detail::is_basic_json<U>::value && detail::is_compatible_type<basic_json_t, U>::value, int > = 0 >
+                   !detail::is_basic_json<U>::value && detail::is_compatible_type<basic_json_t, U>::value
+#if JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
+                   // see https://github.com/nlohmann/json/issues/2226
+                   && !detail::is_basic_json_reference_tuple<basic_json_t, U>::value
+#endif
+                   , int > = 0 >
    basic_json(CompatibleType && val) noexcept(noexcept( // NOLINT(bugprone-forwarding-reference-overload,bugprone-exception-escape)
                JSONSerializer<U>::to_json(std::declval<basic_json_t&>(),
                                           std::forward<CompatibleType>(val))))
@@ -1617,49 +1851,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
          end_position(val.end_pos())
 #endif
    {
-        using other_boolean_t = typename BasicJsonType::boolean_t;
-        using other_number_float_t = typename BasicJsonType::number_float_t;
-        using other_number_integer_t = typename BasicJsonType::number_integer_t;
-        using other_number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-        using other_string_t = typename BasicJsonType::string_t;
-        using other_object_t = typename BasicJsonType::object_t;
-        using other_array_t = typename BasicJsonType::array_t;
-        using other_binary_t = typename BasicJsonType::binary_t;
-
-        switch (val.type())
+        if (val.is_structured())
        {
-            case value_t::boolean:
-                JSONSerializer<other_boolean_t>::to_json(*this, val.template get<other_boolean_t>());
-                break;
-            case value_t::number_float:
-                JSONSerializer<other_number_float_t>::to_json(*this, val.template get<other_number_float_t>());
-                break;
-            case value_t::number_integer:
-                JSONSerializer<other_number_integer_t>::to_json(*this, val.template get<other_number_integer_t>());
-                break;
-            case value_t::number_unsigned:
-                JSONSerializer<other_number_unsigned_t>::to_json(*this, val.template get<other_number_unsigned_t>());
-                break;
-            case value_t::string:
-                JSONSerializer<other_string_t>::to_json(*this, val.template get_ref<const other_string_t&>());
-                break;
-            case value_t::object:
-                JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
-                break;
-            case value_t::array:
-                JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
-                break;
-            case value_t::binary:
-                JSONSerializer<other_binary_t>::to_json(*this, val.template get_ref<const other_binary_t&>());
-                break;
-            case value_t::null:
-                *this = nullptr;
-                break;
-            case value_t::discarded:
-                m_data.m_type = value_t::discarded;
-                break;
-            default:            // LCOV_EXCL_LINE
-                JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
+            convert_structured(val);
+        }
+        else
+        {
+            convert_leaf(val);
        }
        JSON_ASSERT(m_data.m_type == val.type());

@@ -4217,25 +4415,26 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    /// @sa https://json.nlohmann.me/api/basic_json/update/
    void update(const_reference j, bool merge_objects = false)
    {
-        update(j.begin(), j.end(), merge_objects);
+        prepare_update();
+
+        // passed value must be an object (checked here so a type_error names
+        // j, not the copy made below)
+        if (JSON_HEDLEY_UNLIKELY(!j.is_object()))
+        {
+            JSON_THROW(type_error::create(312, detail::concat("cannot use update() with ", j.type_name()), &j));
+        }
+
+        // copy first: j may be *this or one of its descendants, and is
+        // iterated (and moved from) below to update *this
+        basic_json source = j;
+        update_from(source, merge_objects);
    }

    /// @brief updates a JSON object from another object, overwriting existing keys
    /// @sa https://json.nlohmann.me/api/basic_json/update/
    void update(const_iterator first, const_iterator last, bool merge_objects = false) // NOLINT(performance-unnecessary-value-param)
    {
-        // implicitly convert a null value to an empty object
-        if (is_null())
-        {
-            m_data.m_type = value_t::object;
-            m_data.m_value.object = create<object_t>();
-            assert_invariant();
-        }
-
-        if (JSON_HEDLEY_UNLIKELY(!is_object()))
-        {
-            JSON_THROW(type_error::create(312, detail::concat("cannot use update() with ", type_name()), this));
-        }
+        prepare_update();

        // check if range iterators belong to the same JSON object
        if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
@@ -4249,7 +4448,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
            JSON_THROW(type_error::create(312, detail::concat("cannot use update() with ", first.m_object->type_name()), first.m_object));
        }

-        update_members(first, last, merge_objects, 0);
+        // copy first: the range may belong to *this or one of its
+        // descendants, and is iterated (and moved from) below to update
+        // *this
+        basic_json source(first, last);
+        update_from(source, merge_objects);
    }

  private:
@@ -4257,15 +4460,42 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    /// merge_patch_iteratively is merging into, and the members still to merge
    struct merge_frame
    {
-        merge_frame(basic_json* target_, const_iterator position_, const_iterator last_) noexcept
+        merge_frame(basic_json* target_, iterator position_, iterator last_) noexcept
            : target(target_), position(std::move(position_)), last(std::move(last_))
        {}

        basic_json* target;
-        const_iterator position;
-        const_iterator last;
+        iterator position;
+        iterator last;
    };

+    /// @brief converts a null value to an empty object and checks that this
+    /// value is an object; called first by both @ref update overloads
+    void prepare_update()
+    {
+        // implicitly convert a null value to an empty object; create the
+        // object before setting the type, so a throwing allocation leaves
+        // this value null
+        if (is_null())
+        {
+            m_data.m_value.object = create<object_t>();
+            m_data.m_type = value_t::object;
+            assert_invariant();
+        }
+
+        if (JSON_HEDLEY_UNLIKELY(!is_object()))
+        {
+            JSON_THROW(type_error::create(312, detail::concat("cannot use update() with ", type_name()), this));
+        }
+    }
+
+    /// @brief starts the @ref update_members loop over an already-copied @a
+    /// source; called by both @ref update overloads
+    void update_from(basic_json& source, const bool merge_objects)
+    {
+        update_members(source.begin(), source.end(), merge_objects, 0);
+    }
+
    /*!
    @brief the members loop of @ref update, for this object and range

@@ -4278,7 +4508,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    @param[in] depth  nesting level of this object, counted from the object
                      @ref update was called on
    */
-    void update_members(const const_iterator& first, const const_iterator& last, const bool merge_objects, const std::size_t depth)
+    void update_members(const iterator& first, const iterator& last, const bool merge_objects, const std::size_t depth)
    {
        if (JSON_HEDLEY_UNLIKELY(depth >= detail::recursion_depth_limit()))
        {
@@ -4296,13 +4526,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                // are overwritten as usual" behavior (see #5402).
                if (it2 != m_data.m_value.object->end() && it2->second.is_object())
                {
-                    it2->second.update_members(it.value().cbegin(), it.value().cend(), true, depth + 1);
+                    it2->second.update_members(it.value().begin(), it.value().end(), true, depth + 1);
                    continue;
                }
            }
            // set_parent() also repairs the other members, which ordered_json
            // relocates when adding a key makes its vector grow
-            set_parent(m_data.m_value.object->operator[](it.key()) = it.value());
+            set_parent(m_data.m_value.object->operator[](it.key()) = std::move(it.value()));
        }
    }

@@ -4316,7 +4546,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    version. Only reached for values nested deeper than @ref
    detail::recursion_depth_limit.
    */
-    void update_members_iteratively(const_iterator first, const_iterator last)
+    void update_members_iteratively(iterator first, iterator last)
    {
        std::vector<merge_frame> stack;

@@ -4343,18 +4573,18 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                const auto it2 = target->m_data.m_value.object->find(first.key());
                if (it2 != target->m_data.m_value.object->end() && it2->second.is_object())
                {
-                    const basic_json& source = first.value();
+                    basic_json& source = first.value();
                    ++first;
                    stack.emplace_back(target, first, last);
                    target = &it2->second;
-                    first = source.cbegin();
-                    last = source.cend();
+                    first = source.begin();
+                    last = source.end();
                    continue;
                }
            }
            // set_parent() also repairs the other members, which ordered_json
            // relocates when adding a key makes its vector grow
-            target->set_parent(target->m_data.m_value.object->operator[](first.key()) = first.value());
+            target->set_parent(target->m_data.m_value.object->operator[](first.key()) = std::move(first.value()));
            ++first;
        }
    }
@@ -5034,7 +5264,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        auto ia = detail::input_adapter(std::forward<InputType>(i));
        return format == input_format_t::json
               ? parser(std::move(ia), nullptr, true, ignore_comments, ignore_trailing_commas).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(format, sax, strict);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict);
    }

    /// @brief generate SAX events (iterator pair, or iterator+sentinel pair for C++20 ranges support)
@@ -5051,7 +5281,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        auto ia = detail::input_adapter(std::move(first), std::move(last));
        return format == input_format_t::json
               ? parser(std::move(ia), nullptr, true, ignore_comments, ignore_trailing_commas).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(format, sax, strict);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict);
    }

    /// @brief generate SAX events
@@ -5073,7 +5303,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
               // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
               ? parser(std::move(ia), nullptr, true, ignore_comments, ignore_trailing_commas).sax_parse(sax, strict)
               // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
-               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(format, sax, strict);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict);
    }
 #ifndef JSON_NO_IO
    /// @brief deserialize from stream
@@ -5371,7 +5601,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::forward<InputType>(i));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::cbor).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::cbor).sax_parse(&sdp, strict, tag_handler)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5391,7 +5621,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::move(first), std::move(last));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::cbor).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::cbor).sax_parse(&sdp, strict, tag_handler)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5420,7 +5650,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        auto ia = i.get();
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
        // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::cbor).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::cbor).sax_parse(&sdp, strict, tag_handler)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5438,7 +5668,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::forward<InputType>(i));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::msgpack).sax_parse(input_format_t::msgpack, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::msgpack).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5457,7 +5687,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::move(first), std::move(last));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::msgpack).sax_parse(input_format_t::msgpack, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::msgpack).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5484,7 +5714,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        auto ia = i.get();
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
        // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::msgpack).sax_parse(input_format_t::msgpack, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::msgpack).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5502,7 +5732,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::forward<InputType>(i));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::ubjson).sax_parse(input_format_t::ubjson, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::ubjson).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5521,7 +5751,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::move(first), std::move(last));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::ubjson).sax_parse(input_format_t::ubjson, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::ubjson).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5548,7 +5778,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        auto ia = i.get();
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
        // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::ubjson).sax_parse(input_format_t::ubjson, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::ubjson).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5566,7 +5796,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::forward<InputType>(i));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bjdata).sax_parse(input_format_t::bjdata, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bjdata).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5585,7 +5815,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::move(first), std::move(last));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bjdata).sax_parse(input_format_t::bjdata, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bjdata).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5603,7 +5833,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::forward<InputType>(i));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bon8).sax_parse(input_format_t::bon8, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bon8).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5622,7 +5852,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::move(first), std::move(last));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bon8).sax_parse(input_format_t::bon8, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bon8).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5640,7 +5870,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::forward<InputType>(i));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bson).sax_parse(input_format_t::bson, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bson).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5659,7 +5889,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        basic_json result;
        auto ia = detail::input_adapter(std::move(first), std::move(last));
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bson).sax_parse(input_format_t::bson, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bson).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -5686,7 +5916,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        auto ia = i.get();
        detail::json_sax_dom_parser<basic_json, decltype(ia)> sdp(result, allow_exceptions);
        // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
-        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bson).sax_parse(input_format_t::bson, &sdp, strict)) // cppcheck-suppress[accessMoved]
+        if (!binary_reader<decltype(ia)>(std::move(ia), input_format_t::bson).sax_parse(&sdp, strict)) // cppcheck-suppress[accessMoved]
        {
            result = value_t::discarded;
        }
@@ -6363,7 +6593,10 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    /// @sa https://json.nlohmann.me/api/basic_json/merge_patch/
    void merge_patch(const basic_json& apply_patch)
    {
-        apply_merge_patch(apply_patch, 0);
+        // copy first: apply_patch may be *this or one of its descendants,
+        // and is iterated (and moved from) below to patch *this
+        basic_json patch = apply_patch;
+        apply_merge_patch(patch, 0);
    }

  private:
@@ -6376,7 +6609,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    detail::recursion_depth_limit levels have been entered, @ref
    merge_patch_iteratively applies what is left without the call stack.
    */
-    void apply_merge_patch(const basic_json& apply_patch, const std::size_t depth)
+    void apply_merge_patch(basic_json& apply_patch, const std::size_t depth)
    {
        if (apply_patch.is_object())
        {
@@ -6404,7 +6637,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        }
        else
        {
-            *this = apply_patch;
+            *this = std::move(apply_patch);
        }
    }

@@ -6417,12 +6650,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    recursive version. Only reached for patches nested deeper than @ref
    detail::recursion_depth_limit.
    */
-    void merge_patch_iteratively(const basic_json& apply_patch)
+    void merge_patch_iteratively(basic_json& apply_patch)
    {
        std::vector<merge_frame> stack;

        // patch `target` with `patch`, or start patching it member by member
-        const auto apply = [&stack](basic_json & target, const basic_json & patch)
+        const auto apply = [&stack](basic_json & target, basic_json & patch)
        {
            if (patch.is_object())
            {
@@ -6430,11 +6663,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                {
                    target = basic_json::object();
                }
-                stack.emplace_back(&target, patch.cbegin(), patch.cend());
+                stack.emplace_back(&target, patch.begin(), patch.end());
            }
            else
            {
-                target = patch;
+                target = std::move(patch);
            }
        };

@@ -6450,7 +6683,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                continue;
            }

-            const const_iterator member = frame.position;
+            const iterator member = frame.position;
            ++stack.back().position;
            if (member.value().is_null())
            {
@@ -6617,7 +6850,10 @@ struct formatter<nlohmann::NLOHMANN_BASIC_JSON_TPL, char> // NOLINT(cert-dcl58-c

 }  // namespace std

-#include <nlohmann/detail/macro_unscope.hpp>
+// keep: undoes the macros defined via detail/macro_scope.hpp at the top of this file; removing it
+// (nothing in this file *uses* a symbol from it) would leak JSON_* macros into every translation
+// unit that includes this header.
+#include <nlohmann/detail/macro_unscope.hpp> // IWYU pragma: keep

 // End of GCC diagnostic pragmas for C++ modules support
 #if defined(__GNUC__) && !defined(__clang__) && __cplusplus >= 202002L
@@ -11,8 +11,7 @@

 #include <cstdint> // int64_t, uint64_t
 #include <map> // map
-#include <memory> // allocator
-#include <string> // string
+#include <string> // allocator, string
 #include <vector> // vector

 #include <nlohmann/detail/abi_macros.hpp>
@@ -32,7 +31,7 @@ This serializer ignores the template arguments and uses ADL
 for serialization.
 */
 template<typename T = void, typename SFINAE = void>
-struct adl_serializer;
+struct adl_serializer; // IWYU pragma: keep

 /// a class to store JSON values
 /// @sa https://json.nlohmann.me/api/basic_json/
@@ -48,12 +47,12 @@ template<template<typename U, typename V, typename... Args> class ObjectType =
         adl_serializer,
         class BinaryType = std::vector<std::uint8_t>, // cppcheck-suppress syntaxError
         class CustomBaseClass = void>
-class basic_json;
+class basic_json; // IWYU pragma: keep

 /// @brief JSON Pointer defines a string syntax for identifying a specific value within a JSON document
 /// @sa https://json.nlohmann.me/api/json_pointer/
 template<typename RefStringType>
-class json_pointer;
+class json_pointer; // IWYU pragma: keep

 /*!
@brief default specialization
@@ -64,7 +63,7 @@ using json = basic_json<>;
 /// @brief a minimal map-like container that preserves insertion order
 /// @sa https://json.nlohmann.me/api/ordered_map/
 template<class Key, class T, class IgnoredLess, class Allocator>
-struct ordered_map;
+struct ordered_map; // IWYU pragma: keep

 /// @brief specialization that maintains the insertion order of object keys
 /// @sa https://json.nlohmann.me/api/ordered_json/
@@ -12,13 +12,14 @@
 #include <functional> // equal_to, less
 #include <initializer_list> // initializer_list
 #include <iterator> // input_iterator_tag, iterator_traits
-#include <memory> // allocator
+#include <new> // for operator new (placement new)
 #include <stdexcept> // for out_of_range
 #include <tuple> // forward_as_tuple
 #include <type_traits> // enable_if, integral_constant, is_convertible, is_nothrow_move_constructible
 #include <utility> // forward, move, pair, piecewise_construct
-#include <vector> // vector
+#include <vector> // vector, allocator

+#include <nlohmann/detail/abi_macros.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/type_traits.hpp>

@@ -11,8 +11,7 @@

 #include <cstdint> // int64_t, uint64_t
 #include <map> // map
-#include <memory> // allocator
-#include <string> // string
+#include <string> // allocator, string
 #include <vector> // vector

 // #include <nlohmann/detail/abi_macros.hpp>
@@ -177,7 +176,7 @@ This serializer ignores the template arguments and uses ADL
 for serialization.
 */
 template<typename T = void, typename SFINAE = void>
-struct adl_serializer;
+struct adl_serializer; // IWYU pragma: keep

 /// a class to store JSON values
 /// @sa https://json.nlohmann.me/api/basic_json/
@@ -193,12 +192,12 @@ template<template<typename U, typename V, typename... Args> class ObjectType =
         adl_serializer,
         class BinaryType = std::vector<std::uint8_t>, // cppcheck-suppress syntaxError
         class CustomBaseClass = void>
-class basic_json;
+class basic_json; // IWYU pragma: keep

 /// @brief JSON Pointer defines a string syntax for identifying a specific value within a JSON document
 /// @sa https://json.nlohmann.me/api/json_pointer/
 template<typename RefStringType>
-class json_pointer;
+class json_pointer; // IWYU pragma: keep

 /*!
@brief default specialization
@@ -209,7 +208,7 @@ using json = basic_json<>;
 /// @brief a minimal map-like container that preserves insertion order
 /// @sa https://json.nlohmann.me/api/ordered_map/
 template<class Key, class T, class IgnoredLess, class Allocator>
-struct ordered_map;
+struct ordered_map; // IWYU pragma: keep

 /// @brief specialization that maintains the insertion order of object keys
 /// @sa https://json.nlohmann.me/api/ordered_json/
@@ -479,6 +479,77 @@ TEST_CASE("deep copy uses the provided allocator")
    CHECK(copy == j);
 }

+namespace
+{
+// the number of constructions countdown_allocator lets happen, including the
+// one that fails; 0 means none ever fails
+std::size_t constructions_until_failure = 0;
+
+template<class T>
+struct countdown_allocator : std::allocator<T>
+{
+    using std::allocator<T>::allocator;
+
+    template<class U, class... Args>
+    void construct(U* p, Args&& ... args)
+    {
+        if (constructions_until_failure != 0 && --constructions_until_failure == 0)
+        {
+            throw std::bad_alloc();
+        }
+
+        ::new (static_cast<void*>(p)) U(std::forward<Args>(args)...);
+    }
+
+    template <class U>
+    struct rebind
+    {
+        using other = countdown_allocator<U>;
+    };
+};
+} // namespace
+
+TEST_CASE("converting a deeply nested value from another specialization fails cleanly (#5650)")
+{
+    using countdown_json = nlohmann::basic_json<std::map,
+          std::vector,
+          std::string,
+          bool,
+          std::int64_t,
+          std::uint64_t,
+          double,
+          countdown_allocator>;
+
+    // deeper than the 128 levels the converting constructor descends into, so
+    // that failures land on both sides of the bound - or, built with
+    // JSON_NO_THREAD_LOCAL, all in the iterative conversion
+    json j = {1, "two", {{"three", 3}}};
+    for (std::size_t i = 0; i < 150; ++i)
+    {
+        j = json{{"a", json::array({j, "sibling"})}};
+    }
+
+    // Fail every construction in turn. Each failure has to reach the caller,
+    // and everything built until then has to be destroyed cleanly.
+    std::size_t failures = 0;
+    for (std::size_t n = 1;; ++n)
+    {
+        constructions_until_failure = n;
+        try
+        {
+            const countdown_json converted = j;
+            constructions_until_failure = 0;
+            CHECK(converted.dump() == j.dump());
+            break;
+        }
+        catch (const std::bad_alloc&)
+        {
+            ++failures;
+        }
+    }
+    CHECK(failures > 0);
+}
+
 namespace
 {
 template<class T>
@@ -210,15 +210,42 @@ TEST_CASE_TEMPLATE_INVOKE(value_in_range_of_test, \

 TEST_CASE("BJData")
 {
-    SECTION("binary_reader BJData LUT arrays are sorted")
+    SECTION("binary_reader BJData lookup tables")
    {
        std::vector<std::uint8_t> const data;
        auto ia = nlohmann::detail::input_adapter(data);
        // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
        nlohmann::detail::binary_reader<json, decltype(ia)> const br{std::move(ia), json::input_format_t::bjdata};

-        CHECK(std::is_sorted(br.bjd_optimized_type_markers.begin(), br.bjd_optimized_type_markers.end()));
-        CHECK(std::is_sorted(br.bjd_types_map.begin(), br.bjd_types_map.end()));
+        // the excluded optimized-type markers must match binary_writer's
+        // is_bjdata_excluded_type_marker(), which encodes the same 8 markers
+        for (const char marker :
+                {'[', '{', 'S', 'H', 'T', 'F', 'N', 'Z'
+                })
+        {
+            CHECK(br.is_bjd_excluded_optimized_type(marker));
+        }
+        for (const char marker :
+                {'U', 'i', 'u', 'I', 'm', 'l', 'M', 'L', 'd', 'D', 'C', 'B', 'x'
+                })
+        {
+            CHECK(!br.is_bjd_excluded_optimized_type(marker));
+        }
+
+        // every dtype marker must round-trip to its ND-array type name
+        const std::vector<std::pair<char, std::string>> types
+        {
+            {'B', "byte"}, {'C', "char"}, {'D', "double"}, {'I', "int16"},
+            {'L', "int64"}, {'M', "uint64"}, {'U', "uint8"}, {'d', "single"},
+            {'i', "int8"}, {'l', "int32"}, {'m', "uint32"}, {'u', "uint16"}
+        };
+        for (const auto& type : types)
+        {
+            const char* name = br.bjd_type_name(type.first);
+            REQUIRE(name != nullptr);
+            CHECK(std::string(name) == type.second);
+        }
+        CHECK(br.bjd_type_name('x') == nullptr);
    }

    SECTION("individual values")
@@ -141,6 +141,58 @@ TEST_CASE("Better diagnostics with positions")
        check_objects(300);
    }

+    SECTION("converting keeps the positions of nested values (#5650)")
+    {
+        // Values nested deeper than the converting constructor's descent bound
+        // are converted without the call stack, on a path that has to carry the
+        // positions of every value over itself. Objects and arrays take turns,
+        // and the innermost value is null, which used to lose its positions.
+        const auto check_conversion = [](std::size_t depth)
+        {
+            CAPTURE(depth)
+
+            std::string text;
+            std::string closing;
+            for (std::size_t i = 0; i < depth; ++i)
+            {
+                text += (i % 2 == 0) ? "[12, " : R"({"b":1, "a":)";
+                closing += (i % 2 == 0) ? ']' : '}';
+            }
+            text += "null";
+            text.append(closing.rbegin(), closing.rend());
+
+            const json original = json::parse(text);
+            const nlohmann::ordered_json converted = original;
+
+            const json* o = &original;
+            const nlohmann::ordered_json* c = &converted;
+            for (std::size_t level = 0; level <= depth; ++level)
+            {
+                CAPTURE(level)
+                REQUIRE(c->start_pos() == o->start_pos());
+                REQUIRE(c->end_pos() == o->end_pos());
+
+                if (level < depth)
+                {
+                    // the number beside the value nested next
+                    const json& o_number = o->is_object() ? o->at("b") : o->at(0);
+                    const nlohmann::ordered_json& c_number = c->is_object() ? c->at("b") : c->at(0);
+                    REQUIRE(c_number.start_pos() == o_number.start_pos());
+                    REQUIRE(c_number.end_pos() == o_number.end_pos());
+
+                    o = o->is_object() ? &o->at("a") : &o->at(1);
+                    c = c->is_object() ? &c->at("a") : &c->at(1);
+                }
+            }
+        };
+
+        check_conversion(1);
+        check_conversion(127);
+        check_conversion(128);
+        check_conversion(129);
+        check_conversion(300);
+    }
+
    SECTION("JSON patch add to primitive parent (#4292)")
    {
        // the JSON Patch "add" target /foo/bar/baz has a string parent
@@ -236,6 +236,31 @@ TEST_CASE("Regression tests for extended diagnostics")
        }
    }

+    SECTION("Regression test for issue #5641 - parent pointers after update()/merge_patch() with an aliasing argument")
+    {
+        // update()'s and merge_patch()'s argument may be *this or one of its
+        // descendants; the values moved out of the (temporary) copy must end
+        // up with their parent pointing at their new location in *this
+        {
+            json j = {{"a", {{"a", 1}, {"b", 2}}}};
+            j.update(j["a"]);
+            CHECK(j == json({{"a", 1}, {"b", 2}}));
+
+            // Must call operator[] on const element, otherwise m_parent gets updated.
+            auto const& constJ = j;
+            CHECK_THROWS_WITH_AS(constJ["a"].at(0), "[json.exception.type_error.304] (/a) cannot use at() with number", json::type_error);
+        }
+
+        {
+            json j = {{"a", {{"a", nullptr}, {"b", 2}}}};
+            j.merge_patch(j["a"]);
+            CHECK(j == json({{"b", 2}}));
+
+            auto const& constJ = j;
+            CHECK_THROWS_WITH_AS(constJ["b"].at(0), "[json.exception.type_error.304] (/b) cannot use at() with number", json::type_error);
+        }
+    }
+
    SECTION("Regression test for issue #3032 - Yet another assertion failure when inserting into arrays with JSON_DIAGNOSTICS set")
    {
        // reference operator[](size_type idx)
@@ -341,6 +366,36 @@ TEST_CASE("Regression tests for extended diagnostics")
        }
    }

+    SECTION("Regression test for issue #5650 - converting keeps the parents of nested values")
+    {
+        // A value nested deeper than the converting constructor's descent bound
+        // is converted without the call stack. Every container that path creates
+        // has to have the parents of its children set, or the JSON Pointer in the
+        // diagnostic is cut short. Objects and arrays take turns.
+        const std::size_t pairs = 150;
+
+        json j = "not a number";
+        std::string pointer;
+        for (std::size_t i = 0; i < pairs; ++i)
+        {
+            j = json{{"a", json::array({j})}};
+            pointer += "/a/0";
+        }
+
+        const nlohmann::ordered_json converted = j;
+
+        const nlohmann::ordered_json* inner = &converted;
+        for (std::size_t i = 0; i < pairs; ++i)
+        {
+            inner = &inner->at("a").at(0);
+        }
+
+        std::string const expected = "[json.exception.type_error.302] (" + pointer + ") type must be number, but is string";
+        int i = 0;
+        CHECK_THROWS_WITH_AS(i = inner->get<int>(), expected.c_str(), nlohmann::ordered_json::type_error);
+        CHECK(i == 0);
+    }
+
    SECTION("Regression test for issue #5668 - wrong path for std::map/unordered_map with non-string keys")
    {
        // a map with non-string keys is read from an array of [key, value] arrays;
@@ -0,0 +1,93 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+// This file tests the opt-in JSON_DISABLE_TUPLE_REFERENCE_CONVERSION, so it
+// defines the macro itself rather than relying on a -D flag, and runs in every
+// build.
+#ifdef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
+    #undef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
+#endif
+
+#define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 1
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+using nlohmann::ordered_json;
+
+#include <string>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+// clang before 4 and GCC before 5 cannot create a std::tuple of basic_json
+// references at all, with or without JSON_DISABLE_TUPLE_REFERENCE_CONVERSION:
+// the tuple constructors make them instantiate basic_json's conversion operator
+// for libstdc++'s internal tuple bases, which fails hard
+#if (defined(__clang__) && __clang_major__ < 4) || (!defined(__clang__) && defined(__GNUC__) && __GNUC__ < 5)
+    #define SKIP_TESTS_FOR_JSON_REFERENCE_TUPLES
+#endif
+
+TEST_CASE("JSON_DISABLE_TUPLE_REFERENCE_CONVERSION")
+{
+    SECTION("json is not constructible from a one-element tuple of a json reference")
+    {
+        CHECK_FALSE(std::is_constructible<json, std::tuple<json&>>::value);
+        CHECK_FALSE(std::is_constructible<json, std::tuple<const json&>>::value);
+        CHECK_FALSE(std::is_constructible < json, std::tuple < json && >>::value);
+        CHECK_FALSE(std::is_constructible<json, const std::tuple<json&>&>::value);
+        CHECK_FALSE(std::is_constructible<ordered_json, std::tuple<ordered_json&>>::value);
+    }
+
+#ifndef SKIP_TESTS_FOR_JSON_REFERENCE_TUPLES
+    SECTION("issue #2226 - tuple<const json&> from tuple<json&> keeps the reference")
+    {
+        json j = true;
+        const std::tuple<const json&> tup(std::forward_as_tuple(j));
+        CHECK(&std::get<0>(tup) == &j);
+    }
+
+    SECTION("tuple<json> from tuple<json&> copies the element")
+    {
+        const json j = {{"key", "value"}};
+        const std::tuple<json> t1(std::forward_as_tuple(j));
+        CHECK(std::get<0>(t1) == j);
+
+        json j2 = "text";
+        const std::tuple<json> t2(std::forward_as_tuple(std::move(j2)));
+        CHECK(std::get<0>(t2) == "text");
+    }
+#endif
+
+    SECTION("other tuple conversions are not affected")
+    {
+        const json j = true;
+
+        // one-element tuple holding a json value
+        CHECK(json(std::make_tuple(j)) == json::array({true}));
+
+        // tuples with more than one element, even when holding references
+        int i = 1;
+#ifndef SKIP_TESTS_FOR_JSON_REFERENCE_TUPLES
+        CHECK(json(std::forward_as_tuple(i, j)) == json::array({1, true}));
+        CHECK(json(std::forward_as_tuple(j, j)) == json::array({true, true}));
+#endif
+
+        // one-element tuples holding references to other types
+        std::string s = "text";
+        CHECK(json(std::forward_as_tuple(s)) == json::array({"text"}));
+        CHECK(json(std::forward_as_tuple(i)) == json::array({1}));
+
+#ifndef SKIP_TESTS_FOR_JSON_REFERENCE_TUPLES
+        // a reference to a different basic_json specialization
+        ordered_json oj = true;
+        CHECK(json(std::forward_as_tuple(oj)) == json::array({true}));
+#endif
+    }
+}
@@ -47,21 +47,6 @@ TEST_CASE("Tests with disabled exceptions")
        delete sax_no_exception::error_string; // NOLINT(cppcoreguidelines-owning-memory)
    }

-    SECTION("issue #5672 - value(json_pointer, default) must not abort for array tokens that are not a valid index")
-    {
-        const json j = {1, 2, 3};
-
-        // a syntactically valid index that is out of range for this array
-        CHECK(j.value("/7"_json_pointer, 42) == 42);
-        // a reference token that is not a number at all
-        CHECK(j.value("/1a"_json_pointer, 42) == 42);
-        // the empty reference token (JSON pointer "/")
-        CHECK(j.value("/"_json_pointer, 42) == 42);
-        // an index whose magnitude does not fit into size_type
-        CHECK(j.value("/99999999999999999999999"_json_pointer, 42) == 42);
-        CHECK(j.value("/18446744073709551615"_json_pointer, 42) == 42);
-    }
-
    SECTION("growing an ordered_json object")
    {
        auto j = nlohmann::ordered_json::object();
@@ -516,21 +516,6 @@ TEST_CASE_TEMPLATE("element access 2", Json, nlohmann::json, nlohmann::ordered_j
                    CHECK(j_array.value("/-"_json_pointer, 42) == 42);
                    CHECK(j_array_const.value("/-"_json_pointer, 42) == 42);

-                    // Test an index with a non-digit after a valid leading digit; this is
-                    // out_of_range (not parse_error) and must not throw (see #5672)
-                    CHECK(j_array.value("/1a"_json_pointer, 42) == 42);
-                    CHECK(j_array_const.value("/1a"_json_pointer, 42) == 42);
-
-                    // Test the empty reference token (JSON pointer "/"); see #5672
-                    CHECK(j_array.value("/"_json_pointer, 42) == 42);
-                    CHECK(j_array_const.value("/"_json_pointer, 42) == 42);
-
-                    // Test an index whose magnitude does not fit into size_type (see #5672)
-                    CHECK(j_array.value("/99999999999999999999999"_json_pointer, 42) == 42);
-                    CHECK(j_array_const.value("/99999999999999999999999"_json_pointer, 42) == 42);
-                    CHECK(j_array.value("/18446744073709551615"_json_pointer, 42) == 42);
-                    CHECK(j_array_const.value("/18446744073709551615"_json_pointer, 42) == 42);
-
 #if !defined(JSON_NOEXCEPTION)
                    // Test malformed index (non-numeric) throws parse_error
                    CHECK_THROWS_WITH_AS(j_array.value("/foo"_json_pointer, 1), "[json.exception.parse_error.109] parse error: array index 'foo' is not a number", typename Json::parse_error&);
@@ -13,6 +13,7 @@ using nlohmann::json;

 #include <algorithm>
 #include <string>
+#include <vector>

 TEST_CASE("tests on very large JSONs")
 {
@@ -53,6 +54,24 @@ const json* innermost_value(const json& j, std::size_t& depth)
    return current;
 }

+// The text of a value nested depth levels deep around the number 0. Level i is
+// an array if pattern[i % pattern.size()] is '[', and otherwise an object with
+// the single member "a", which every object type enumerates in the same order.
+std::string nested_text(std::size_t depth, const std::string& pattern)
+{
+    std::string text;
+    std::string closing;
+    for (std::size_t i = 0; i < depth; ++i)
+    {
+        const bool array = pattern[i % pattern.size()] == '[';
+        text += array ? "[" : "{\"a\":";
+        closing += array ? ']' : '}';
+    }
+    text += '0';
+    text.append(closing.rbegin(), closing.rend());
+    return text;
+}
+
 } // namespace

 TEST_CASE("tests on deeply nested JSONs")
@@ -224,5 +243,114 @@ TEST_CASE("tests on deeply nested JSONs")
            CHECK(*innermost_value(j, unused) == 0);
        }
    }
+
+    SECTION("issue #5650 - stack overflow converting between specializations")
+    {
+        const std::vector<std::string> patterns = {"[", "{", "[{"};
+
+        SECTION("json to ordered_json")
+        {
+            for (const auto& pattern : patterns)
+            {
+                CAPTURE(pattern);
+                const std::string text = nested_text(depth, pattern);
+                const json j = json::parse(text);
+
+                const nlohmann::ordered_json converted = j;
+                CHECK(converted.dump() == text);
+            }
+        }
+
+        SECTION("ordered_json to json")
+        {
+            for (const auto& pattern : patterns)
+            {
+                CAPTURE(pattern);
+                const std::string text = nested_text(depth, pattern);
+                const nlohmann::ordered_json o = nlohmann::ordered_json::parse(text);
+
+                const json converted = o;
+                CHECK(converted.dump() == text);
+            }
+        }
+
+        SECTION("get<ordered_json>()")
+        {
+            for (const auto& pattern : patterns)
+            {
+                CAPTURE(pattern);
+                const std::string text = nested_text(depth, pattern);
+                const json j = json::parse(text);
+
+                CHECK(j.get<nlohmann::ordered_json>().dump() == text);
+            }
+        }
+
+        SECTION("depths around the bound of the recursive descent")
+        {
+            for (std::size_t d = 1; d <= 300; ++d)
+            {
+                CAPTURE(d);
+                for (const auto& pattern : patterns)
+                {
+                    CAPTURE(pattern);
+                    const std::string text = nested_text(d, pattern);
+                    const json j = json::parse(text);
+
+                    const nlohmann::ordered_json converted = j;
+                    CHECK(converted.dump() == text);
+                    const json back = converted;
+                    CHECK(back.dump() == text);
+                }
+            }
+        }
+
+        SECTION("values below the bound are converted as values above it")
+        {
+            // Bury a value below the bound, where it is converted without the
+            // call stack, and compare it with the same value converted on its
+            // own by the containers' range constructors. Its objects have
+            // members that the two object types enumerate in different orders.
+            const auto bury = [](nlohmann::ordered_json value)
+            {
+                for (std::size_t i = 0; i < 200; ++i)
+                {
+                    value = nlohmann::ordered_json::array({std::move(value)});
+                }
+                return value;
+            };
+            const auto dig = [](const json & value)
+            {
+                const json* current = &value;
+                for (std::size_t i = 0; i < 200; ++i)
+                {
+                    current = &current->at(0);
+                }
+                return current;
+            };
+
+            nlohmann::ordered_json value = nlohmann::ordered_json::object();
+            value["z"] = {1, -2, 3U, 4.5, true, nullptr, "six", nlohmann::ordered_json::binary({7, 8}, 9),
+                          nlohmann::ordered_json::binary({10}), nlohmann::ordered_json::array(), nlohmann::ordered_json::object()
+                         };
+            value["y"] = {{"x", {{"w", 1}, {"v", 2}}}, {"u", {3, {{"t", 4}, {"s", 5}}}}};
+            value["r"] = nlohmann::ordered_json::array({nlohmann::ordered_json(nlohmann::ordered_json::value_t::discarded)});
+
+            const json converted_above = value;
+            const json buried = bury(value);
+            const json& converted_below = *dig(buried);
+
+            CHECK(converted_below.dump() == converted_above.dump());
+            CHECK(converted_below.at("z").at(7).get_binary().subtype() == 9);
+            CHECK_FALSE(converted_below.at("z").at(8).get_binary().has_subtype());
+            CHECK(converted_below.at("r").at(0).is_discarded());
+
+            // a discarded value is never equal to anything, so compare the rest
+            value.erase("r");
+            const json without_discarded_above = value;
+            const json without_discarded_buried = bury(value);
+            CHECK(*dig(without_discarded_buried) == without_discarded_above);
+        }
+    }
 }

@@ -374,3 +374,52 @@ TEST_CASE("JSON Merge Patch and update on ordered_json")
        CHECK(target == ordered_json::parse(R"({"a": 1, "e": {"y": 5}, "g": 6})"));
    }
 }
+
+TEST_CASE("merge_patch() with an argument that aliases *this (#5641)")
+{
+    SECTION("j.merge_patch(j): erasing a member destroys the node the loop's iterator points to")
+    {
+        // reproduces issue #5641, case 1
+        json j = {{"a", nullptr}, {"b", 1}};
+        j.merge_patch(j);
+        CHECK(j == json({{"b", 1}}));
+    }
+
+    SECTION("j.merge_patch(j[\"a\"]): removing \"a\" destroys the patch while it is iterated")
+    {
+        // reproduces issue #5641, case 2
+        json j = {{"a", {{"a", nullptr}, {"b", 2}}}};
+        j.merge_patch(j["a"]);
+        CHECK(j == json({{"b", 2}}));
+    }
+
+    SECTION("a patch nested past the iterative descent bound aliases *this")
+    {
+        // every depth on either side of where the iterative version takes
+        // over (detail::recursion_depth_limit(), 128); patching *this with
+        // itself is idempotent, aliased or not
+        for (const std::size_t depth :
+                {
+                    std::size_t{0}, std::size_t{127}, std::size_t{128}, std::size_t{300}
+                })
+        {
+            CAPTURE(depth);
+            json j = json::parse(nested_objects(depth, 0));
+            const json expected = j;
+            j.merge_patch(j);
+            CHECK(j == expected);
+        }
+    }
+
+    SECTION("ordered_json")
+    {
+        using nlohmann::ordered_json;
+
+        SECTION("merge_patch with a member of *this")
+        {
+            ordered_json j = {{"a", {{"a", nullptr}, {"b", 2}}}};
+            j.merge_patch(j["a"]);
+            CHECK(j == ordered_json({{"b", 2}}));
+        }
+    }
+}
@@ -1116,3 +1116,72 @@ TEST_CASE("update() on deeply nested values")
        CHECK(p->at("y") == 2);
    }
 }
+
+TEST_CASE("update() with an argument that aliases *this (#5641)")
+{
+    SECTION("the target is checked before the argument, as before the copy")
+    {
+        json j = 1;
+        CHECK_THROWS_WITH_AS(j.update(json::array()), "[json.exception.type_error.312] cannot use update() with number", json::type_error&);
+        CHECK_THROWS_WITH_AS(j.update(j.cbegin(), j.cend()), "[json.exception.type_error.312] cannot use update() with number", json::type_error&);
+
+        json k;
+        CHECK_THROWS_WITH_AS(k.update(json::array()), "[json.exception.type_error.312] cannot use update() with array", json::type_error&);
+        CHECK(k == json::object());
+    }
+
+    SECTION("const reference")
+    {
+        SECTION("j.update(j[\"a\"]): assigning into the argument's parent destroys it mid-iteration")
+        {
+            // reproduces issue #5641, case 3
+            json j = {{"a", {{"a", 1}, {"b", 2}}}};
+            j.update(j["a"]);
+            CHECK(j == json({{"a", 1}, {"b", 2}}));
+        }
+
+        SECTION("merge_objects with an argument that is a member of *this")
+        {
+            json j = {{"defaults", {{"opts", {{"a", 1}}}}}, {"opts", {{"b", 2}}}};
+            j.update(j["defaults"], true);
+            CHECK(j == json({{"defaults", {{"opts", {{"a", 1}}}}}, {"opts", {{"a", 1}, {"b", 2}}}}));
+        }
+
+        SECTION("ordered_json: inserting a new key relocates the vector behind the argument")
+        {
+            // reproduces issue #5641, case 4
+            using nlohmann::ordered_json;
+            ordered_json j = {{"a", {{"x", 1}, {"y", 2}, {"z", 3}}}};
+            j.update(j["a"]);
+            CHECK(j == ordered_json({{"a", {{"x", 1}, {"y", 2}, {"z", 3}}}, {"x", 1}, {"y", 2}, {"z", 3}}));
+        }
+    }
+
+    SECTION("iterator range")
+    {
+        SECTION("range that is a member of *this")
+        {
+            json j = {{"a", {{"a", 1}, {"b", 2}}}};
+            j.update(j["a"].begin(), j["a"].end());
+            CHECK(j == json({{"a", 1}, {"b", 2}}));
+        }
+    }
+
+    SECTION("nested past the iterative descent bound aliases *this")
+    {
+        // every depth on either side of where the iterative version takes
+        // over (detail::recursion_depth_limit(), 128); merging *this into
+        // itself is idempotent, aliased or not
+        for (const std::size_t depth :
+                {
+                    std::size_t{0}, std::size_t{127}, std::size_t{128}, std::size_t{300}
+                })
+        {
+            CAPTURE(depth);
+            json j = json::parse(nested_objects(depth, 0));
+            const json expected = j;
+            j.update(j, true);
+            CHECK(j == expected);
+        }
+    }
+}
@@ -18,6 +18,19 @@
 // for some reason including this after the json header leads to linker errors with VS 2017...
 #include <locale>

+// skip tests if JSON_DISABLE_TUPLE_REFERENCE_CONVERSION=1 (#2226)
+#if defined(JSON_DISABLE_TUPLE_REFERENCE_CONVERSION) && (JSON_DISABLE_TUPLE_REFERENCE_CONVERSION == 1)
+    #define SKIP_TESTS_FOR_TUPLE_REFERENCE_CONVERSION
+#endif
+
+// clang before 4 and GCC before 5 cannot create a std::tuple of basic_json
+// references at all, with or without JSON_DISABLE_TUPLE_REFERENCE_CONVERSION:
+// the tuple constructors make them instantiate basic_json's conversion operator
+// for libstdc++'s internal tuple bases, which fails hard
+#if (defined(__clang__) && __clang_major__ < 4) || (!defined(__clang__) && defined(__GNUC__) && __GNUC__ < 5)
+    #define SKIP_TESTS_FOR_JSON_REFERENCE_TUPLES
+#endif
+
 #define JSON_TESTS_PRIVATE
 #include <nlohmann/json.hpp>
 using json = nlohmann::json;
@@ -28,6 +41,7 @@ using ordered_json = nlohmann::ordered_json;

 #include <cstdio>
 #include <list>
+#include <tuple>
 #include <type_traits>
 #include <utility>

@@ -542,6 +556,20 @@ TEST_CASE("regression tests 2")
                      )));
    }

+#ifndef SKIP_TESTS_FOR_TUPLE_REFERENCE_CONVERSION
+    SECTION("issue #2226 - std::tuple dangling reference - implicit conversion")
+    {
+        // by default, a one-element tuple holding a json reference converts to
+        // a one-element array; JSON_DISABLE_TUPLE_REFERENCE_CONVERSION removes
+        // this conversion (see unit-disable-tuple-reference-conversion.cpp)
+        const json j = true;
+        CHECK(std::is_constructible<json, std::tuple<const json&>>::value);
+#ifndef SKIP_TESTS_FOR_JSON_REFERENCE_TUPLES
+        CHECK(json(std::forward_as_tuple(j)) == json::array({true}));
+#endif
+    }
+#endif
+
    SECTION("PR #2181 - regression bug with lvalue")
    {
        // see https://github.com/nlohmann/json/pull/2181#issuecomment-653326060
@@ -3033,3 +3033,224 @@ TEST_CASE("UBJSON optimized array of unsigned integers beyond int64")
    CHECK(json::to_ubjson(j, true, true) == expected);
    CHECK(json::from_ubjson(expected) == j);
 }
+
+namespace
+{
+// the bytes that follow the marker of an integer: the value in the width of
+// the marker (big endian for UBJSON, little endian for BJData), or, for a
+// high-precision number, the length and the decimal digits
+std::vector<std::uint8_t> integer_payload(const char marker, const json& value, const bool little_endian)
+{
+    std::size_t width = 0;
+    switch (marker)
+    {
+        case 'i':
+        case 'U':
+            width = 1;
+            break;
+        case 'I':
+        case 'u':
+            width = 2;
+            break;
+        case 'l':
+        case 'm':
+            width = 4;
+            break;
+        case 'L':
+        case 'M':
+            width = 8;
+            break;
+        default:
+        {
+            const std::string digits = value.dump();
+            std::vector<std::uint8_t> result = {'i', static_cast<std::uint8_t>(digits.size())};
+            for (const char c : digits)
+            {
+                result.push_back(static_cast<std::uint8_t>(c));
+            }
+            return result;
+        }
+    }
+
+    const std::uint64_t bits = value.is_number_unsigned()
+                               ? value.get<std::uint64_t>()
+                               : static_cast<std::uint64_t>(value.get<std::int64_t>());
+    std::vector<std::uint8_t> result(width);
+    for (std::size_t i = 0; i < width; ++i)
+    {
+        result[little_endian ? i : width - 1 - i] = static_cast<std::uint8_t>(bits >> (8 * i));
+    }
+    return result;
+}
+
+json i64(const std::int64_t v)
+{
+    return v;
+}
+
+json u64(const std::uint64_t v)
+{
+    return v;
+}
+} // namespace
+
+TEST_CASE("UBJSON and BJData integer markers at every range edge")
+{
+    // An optimized container announces the marker of its values after `$` and
+    // then writes every value without a marker, so the marker the writer
+    // announces and the width it writes must match for every value. This
+    // checks both for the values around each edge of the integer types, as
+    // scalars and as the values of optimized arrays and objects.
+    struct integer_case
+    {
+        json value;
+        char ubjson; // expected UBJSON marker
+        char bjdata; // expected BJData marker
+    };
+
+    const std::int64_t int64_min = (std::numeric_limits<std::int64_t>::min)();
+    const std::int64_t int64_max = (std::numeric_limits<std::int64_t>::max)();
+    const std::uint64_t uint64_max = (std::numeric_limits<std::uint64_t>::max)();
+
+    const std::vector<integer_case> cases =
+    {
+        // int8
+        {i64(-129), 'I', 'I'},
+        {i64(-128), 'i', 'i'},
+        {i64(-127), 'i', 'i'},
+        {i64(-1), 'i', 'i'},
+        {i64(0), 'i', 'i'},
+        {u64(0), 'i', 'i'},
+        {i64(126), 'i', 'i'},
+        {i64(127), 'i', 'i'},
+        {u64(127), 'i', 'i'},
+        {i64(128), 'U', 'U'},
+        {u64(128), 'U', 'U'},
+        // uint8
+        {i64(254), 'U', 'U'},
+        {i64(255), 'U', 'U'},
+        {u64(255), 'U', 'U'},
+        {i64(256), 'I', 'I'},
+        {u64(256), 'I', 'I'},
+        // int16
+        {i64(-32769), 'l', 'l'},
+        {i64(-32768), 'I', 'I'},
+        {i64(-32767), 'I', 'I'},
+        {i64(32766), 'I', 'I'},
+        {i64(32767), 'I', 'I'},
+        {u64(32767), 'I', 'I'},
+        {i64(32768), 'l', 'u'},
+        {u64(32768), 'l', 'u'},
+        // uint16 (BJData only)
+        {i64(65534), 'l', 'u'},
+        {i64(65535), 'l', 'u'},
+        {u64(65535), 'l', 'u'},
+        {i64(65536), 'l', 'l'},
+        {u64(65536), 'l', 'l'},
+        // int32
+        {i64(-2147483649LL), 'L', 'L'},
+        {i64(-2147483648LL), 'l', 'l'},
+        {i64(-2147483647LL), 'l', 'l'},
+        {i64(2147483646LL), 'l', 'l'},
+        {i64(2147483647LL), 'l', 'l'},
+        {u64(2147483647ULL), 'l', 'l'},
+        {i64(2147483648LL), 'L', 'm'},
+        {u64(2147483648ULL), 'L', 'm'},
+        // uint32 (BJData only)
+        {i64(4294967294LL), 'L', 'm'},
+        {i64(4294967295LL), 'L', 'm'},
+        {u64(4294967295ULL), 'L', 'm'},
+        {i64(4294967296LL), 'L', 'L'},
+        {u64(4294967296ULL), 'L', 'L'},
+        // int64
+        {i64(int64_min), 'L', 'L'},
+        {i64(int64_min + 1), 'L', 'L'},
+        {i64(int64_max - 1), 'L', 'L'},
+        {i64(int64_max), 'L', 'L'},
+        {u64(static_cast<std::uint64_t>(int64_max)), 'L', 'L'},
+        // uint64 (BJData only; UBJSON writes a high-precision number)
+        {u64(static_cast<std::uint64_t>(int64_max) + 1), 'H', 'M'},
+        {u64(uint64_max - 1), 'H', 'M'},
+        {u64(uint64_max), 'H', 'M'},
+    };
+
+    for (const auto& c : cases)
+    {
+        for (const bool bjdata :
+                {
+                    false, true
+                })
+        {
+            const char marker = bjdata ? c.bjdata : c.ubjson;
+            const std::vector<std::uint8_t> payload = integer_payload(marker, c.value, bjdata);
+            const auto to_binary = [bjdata](const json & j, const bool use_size, const bool use_type)
+            {
+                return bjdata ? json::to_bjdata(j, use_size, use_type) : json::to_ubjson(j, use_size, use_type);
+            };
+            const auto from_binary = [bjdata](const std::vector<std::uint8_t>& v)
+            {
+                return bjdata ? json::from_bjdata(v) : json::from_ubjson(v);
+            };
+            INFO("value = " << c.value.dump() << (c.value.is_number_unsigned() ? " (unsigned)" : "") << ", format = " << (bjdata ? "BJData" : "UBJSON"));
+
+            // scalar
+            std::vector<std::uint8_t> expected = {static_cast<std::uint8_t>(marker)};
+            expected.insert(expected.end(), payload.begin(), payload.end());
+            for (const bool use_size :
+                    {
+                        false, true
+                    })
+            {
+                CHECK(to_binary(c.value, use_size, false) == expected);
+            }
+            CHECK(from_binary(expected) == c.value);
+
+            const json arr = {c.value, c.value, c.value};
+
+            // array without count or type: every value has its marker
+            expected = {'['};
+            for (int i = 0; i < 3; ++i)
+            {
+                expected.push_back(static_cast<std::uint8_t>(marker));
+                expected.insert(expected.end(), payload.begin(), payload.end());
+            }
+            expected.push_back(']');
+            CHECK(to_binary(arr, false, false) == expected);
+            CHECK(from_binary(expected) == arr);
+
+            // array with count: every value has its marker
+            expected = {'[', '#', 'i', 3};
+            for (int i = 0; i < 3; ++i)
+            {
+                expected.push_back(static_cast<std::uint8_t>(marker));
+                expected.insert(expected.end(), payload.begin(), payload.end());
+            }
+            CHECK(to_binary(arr, true, false) == expected);
+            CHECK(from_binary(expected) == arr);
+
+            // array with type and count: the marker once, then the payloads
+            expected = {'[', '$', static_cast<std::uint8_t>(marker), '#', 'i', 3};
+            for (int i = 0; i < 3; ++i)
+            {
+                expected.insert(expected.end(), payload.begin(), payload.end());
+            }
+            CHECK(to_binary(arr, true, true) == expected);
+            CHECK(from_binary(expected) == arr);
+
+            // object with type and count: the marker once, then key and payload
+            const json obj = {{"a", c.value}, {"b", c.value}};
+            expected = {'{', '$', static_cast<std::uint8_t>(marker), '#', 'i', 2};
+            for (const char key :
+                    {'a', 'b'
+                    })
+            {
+                expected.push_back('i');
+                expected.push_back(1);
+                expected.push_back(static_cast<std::uint8_t>(key));
+                expected.insert(expected.end(), payload.begin(), payload.end());
+            }
+            CHECK(to_binary(obj, true, true) == expected);
+            CHECK(from_binary(expected) == obj);
+        }
+    }
+}
@@ -7,4 +7,22 @@
 // SPDX-License-Identifier: MIT

 #define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
+
+// libc++ annotates std::mutex for Clang's thread safety analysis, so -Weverything
+// reports -Wthread-safety-negative for the locks in doctest's reporters, which are
+// only compiled in this file. __has_warning keeps older Clang versions from
+// reporting an unknown warning group.
+#if defined(__clang__) && defined(__has_warning)
+    #if __has_warning("-Wthread-safety-negative")
+        #pragma clang diagnostic push
+        #pragma clang diagnostic ignored "-Wthread-safety-negative"
+    #endif
+#endif
+
 #include "doctest_compatibility.h"
+
+#if defined(__clang__) && defined(__has_warning)
+    #if __has_warning("-Wthread-safety-negative")
+        #pragma clang diagnostic pop
+    #endif
+#endif
@@ -1,8 +1,8 @@
 # amalgamate.py - Amalgamate C source and header files

-Origin: https://bitbucket.org/erikedlund/amalgamate
-
-Mirror: https://github.com/edlund/amalgamate
+Origin: https://github.com/edlund/amalgamate (formerly hosted at
+https://bitbucket.org/erikedlund/amalgamate, which no longer exists; see
+`CHANGES.md` for the upstream commit this copy is based on)

 `amalgamate.py` aims to make it easy to use SQLite-style C source and header
 amalgamation in projects.
@@ -41,21 +41,22 @@ results.

 ## Installing amalgamate.py

-Python v.2.7.0 or higher is required.
+Python 3 is required.

-`amalgamate.py` can be tested and installed using the following commands:
-
-        ./test.sh && sudo -k cp ./amalgamate.py /usr/local/bin/
+In this repository, `amalgamate.py` is not installed separately; it is run in
+place through `make amalgamate`, which calls it once for `json.hpp` and once
+for `json_fwd.hpp` (see the root `Makefile`).

 ## Using amalgamate.py

-        amalgamate.py [-v] -c path/to/config.json -s path/to/source/dir \
-                [-p path/to/prologue.(c|h)]
+        amalgamate.py -c path/to/config.json -s path/to/source/dir \
+                [-p path/to/prologue.(c|h)] [--verbose=yes|no]

 * The `-c, --config` option should specify the path to a JSON config file which
   lists the source files, include paths and where to write the resulting
-   amalgamation. Have a look at `test/source.c.json` and `test/include.h.json`
-   to see two examples.
+   amalgamation. `config_json.json` and `config_json_fwd.json` in this
+   directory are the configs used for `json.hpp` and `json_fwd.hpp`; each
+   sets `target`, `sources` and `include_paths`.

   The optional `external` list names include paths that are kept as `#include`
   directives instead of being inlined, e.g. `["nlohmann/json.hpp"]` for a header
@@ -68,3 +69,6 @@ Python v.2.7.0 or higher is required.
 * The `-p, --prologue` option should specify the path to a file which will be
   added to the beginning of the amalgamation. It is optional.

+ * The `-v, --verbose` option takes `yes` or `no` (for example
+   `--verbose=yes`, as used by the Makefile). It is optional.
+
@@ -1 +1,4 @@
+# astyle is deliberately pinned: newer versions reformat the code, and this version
+# defines the formatting that `make amalgamate` produces and check_amalgamation.yml enforces.
+# Dependabot is told to ignore it in .github/dependabot.yml.
 astyle==3.4.13
@@ -2,8 +2,26 @@

 Generate the Natvis debugger visualization file for all supported namespace combinations.

+The ABI tag list and the library version are parsed from
+`include/nlohmann/detail/abi_macros.hpp`, so this script must be re-run (via
+`make natvis`) whenever an `NLOHMANN_JSON_ABI_TAG_*` macro is added to that
+file or the library version is bumped — otherwise the committed
+`nlohmann_json.natvis` drifts from the header it visualizes, and
+`make check-amalgamation` fails.
+
 ## Usage

 ```shell
-./generate_natvis.py --version X.Y.Z output_directory/
+make natvis
 ```
+
+or, equivalently:
+
+```shell
+./generate_natvis.py [--version X.Y.Z] [repository_root/]
+```
+
+`--version` and the output/repository-root directory both default to values
+derived from this script's own location, so they only need to be given
+explicitly when generating a Natvis file for a different checkout or a
+version other than the one in `abi_macros.hpp`.
@@ -7,21 +7,75 @@ import os
 import re
 import sys

+# Directory of the repository, assuming this script stays at
+# tools/generate_natvis/generate_natvis.py. Used only as the default value
+# for the "output" argument below.
+REPO_ROOT = os.path.normpath(os.path.join(sys.path[0], '..', '..'))
+
+
 def semver(v):
    if not re.fullmatch(r'\d+\.\d+\.\d+', v):
        raise ValueError
    return v

+
+def abi_info(repo_root):
+    """Derive the ABI tag list (in NLOHMANN_JSON_ABI_TAGS_CONCAT order) and the
+    library version from <repo_root>/include/nlohmann/detail/abi_macros.hpp,
+    so this script cannot drift from the header it visualizes."""
+    abi_macros_hpp = os.path.join(repo_root, 'include', 'nlohmann', 'detail', 'abi_macros.hpp')
+    with open(abi_macros_hpp) as f:
+        content = f.read()
+
+    # find the NLOHMANN_JSON_ABI_TAGS_CONCAT(...) invocation that lists the
+    # NLOHMANN_JSON_ABI_TAG_* identifiers in order (not its own #define, which
+    # only names its formal parameters a, b, c, ...)
+    tag_idents = None
+    for args in re.findall(r'NLOHMANN_JSON_ABI_TAGS_CONCAT\(\s*(.*?)\)', content, re.S):
+        idents = re.findall(r'NLOHMANN_JSON_ABI_TAG_\w+', args)
+        if idents:
+            tag_idents = idents
+            break
+    if not tag_idents:
+        raise ValueError(f'could not find NLOHMANN_JSON_ABI_TAGS_CONCAT(...) in {abi_macros_hpp}')
+
+    abi_tags = []
+    for ident in tag_idents:
+        # each tag is #define'd to its suffix (e.g. _diag) when the matching
+        # JSON_* option is enabled, and to nothing in the #else branch; only
+        # the non-empty definition matches here
+        match = re.search(r'#define\s+' + re.escape(ident) + r'\s+(_\w+)\s*\n', content)
+        if not match:
+            raise ValueError(f'could not find a non-empty #define for {ident} in {abi_macros_hpp}')
+        abi_tags.append(match.group(1))
+
+    version = {}
+    for part in ('MAJOR', 'MINOR', 'PATCH'):
+        match = re.search(r'#define\s+NLOHMANN_JSON_VERSION_' + part + r'\s+(\d+)', content)
+        if not match:
+            raise ValueError(f'could not find NLOHMANN_JSON_VERSION_{part} in {abi_macros_hpp}')
+        version[part] = match.group(1)
+
+    return abi_tags, '{MAJOR}.{MINOR}.{PATCH}'.format(**version)
+
+
 if __name__ == '__main__':
    parser = argparse.ArgumentParser()
-    parser.add_argument('--version', required=True, type=semver, help='Library version number')
-    parser.add_argument('output', help='Output directory for nlohmann_json.natvis')
+    parser.add_argument('--version', type=semver,
+                         help='Library version number (default: parsed from '
+                              'include/nlohmann/detail/abi_macros.hpp below "output")')
+    parser.add_argument('output', nargs='?', default=REPO_ROOT,
+                         help='Repository root: where include/nlohmann/detail/abi_macros.hpp is '
+                              'read from and where nlohmann_json.natvis is written '
+                              '(default: the repository root this script lives in)')
    args = parser.parse_args()

+    derived_tags, derived_version = abi_info(args.output)
+
    namespaces = ['nlohmann']
    abi_prefix = 'json_abi'
-    abi_tags = ['_diag', '_ldvcmp', '_dp', '_bics', '_psp', '_snul']
-    version = '_v' + args.version.replace('.', '_')
+    abi_tags = derived_tags
+    version = '_v' + (args.version or derived_version).replace('.', '_')
    inline_namespaces = []

    # generate all combinations of inline namespace names
@@ -0,0 +1,51 @@
+# macro_builder
+
+Generates the argument-counting macros behind the `NLOHMANN_DEFINE_TYPE_*` and `NLOHMANN_DEFINE_DERIVED_TYPE_*`
+macros in [`include/nlohmann/detail/macro_scope.hpp`](../../include/nlohmann/detail/macro_scope.hpp):
+
+- `NLOHMANN_JSON_EXPAND`
+- `NLOHMANN_JSON_GET_MACRO`, which selects a macro by the number of its arguments (64 slots)
+- `NLOHMANN_JSON_PASTE`, which calls a function-like macro for each member, and its helpers `NLOHMANN_JSON_PASTE2`
+  to `NLOHMANN_JSON_PASTE64`
+- `NLOHMANN_JSON_DOUBLE_PASTE`, which the `*_WITH_NAMES` macros use to call a function-like macro for each
+  (JSON name, member) pair, and its helpers `NLOHMANN_JSON_DOUBLE_PASTE3` to `NLOHMANN_JSON_DOUBLE_PASTE63`
+- the slot table of `NLOHMANN_JSON_TYPE_BODY`, which dispatches `NLOHMANN_DEFINE_TYPE_*(Type)` (no further
+  arguments) to the zero-member implementation and every other argument count to the one-or-more-member
+  implementation
+
+The number of slots (`max_args` in [`main.cpp`](main.cpp)) sets the member limit of these macros.
+`NLOHMANN_JSON_PASTE` and `NLOHMANN_JSON_TYPE_BODY` take the function/prefix as their first argument, so 64 slots
+allow 63 members; `NLOHMANN_JSON_DOUBLE_PASTE` additionally consumes its members two at a time (name, member), so
+it only defines the odd helpers up to `NLOHMANN_JSON_DOUBLE_PASTE63`.
+
+## Usage
+
+From the project root:
+
+```shell
+c++ -std=c++11 tools/macro_builder/main.cpp -o macro_builder
+./macro_builder
+./macro_builder type_body
+```
+
+1. Run `./macro_builder` (no arguments). In `include/nlohmann/detail/macro_scope.hpp`, replace the lines from
+   `#define NLOHMANN_JSON_EXPAND( x ) x` to the `#define NLOHMANN_JSON_DOUBLE_PASTE63(...)` line with the output,
+   without its trailing empty line.
+2. Run `./macro_builder type_body`. Replace the lines from `#define NLOHMANN_JSON_TYPE_BODY(Prefix, ...)` to the
+   `NLOHMANN_JSON_TYPE_BODY_SENTINEL))` line with the output.
+3. Run `make amalgamate`. It updates `single_include/nlohmann/json.hpp` and runs `make pretty`, which indents the
+   continuation lines that the tool writes unindented.
+
+With an unchanged `main.cpp`, these steps reproduce both blocks of `macro_scope.hpp` byte for byte. `make
+macro_builder_check` (also run by CI, see `.github/workflows/check_amalgamation.yml`) automates this: it builds
+`main.cpp`, regenerates both blocks, and fails on a diff against the checked-in header.
+
+## Maintained by hand
+
+The tool does not generate everything that depends on the number of slots. When changing `max_args`, also update:
+
+- the documented limit of 63 members in `docs/mkdocs/docs` and the tests at that limit in
+  `tests/src/unit-udt_macro.cpp`
+
+All three tables pass one macro name per slot to `NLOHMANN_JSON_GET_MACRO`, so they need exactly as many entries as
+it has slots.
@@ -1,10 +1,14 @@
 #include <cstdlib>
 #include <iostream>
 #include <sstream>
+#include <string>

 using namespace std;

-void build_code(int max_args)
+// Builds NLOHMANN_JSON_EXPAND, NLOHMANN_JSON_GET_MACRO, and the
+// NLOHMANN_JSON_PASTE / NLOHMANN_JSON_PASTE2..PASTE<max_args> dispatch table
+// and recursive definitions.
+string build_paste_code(int max_args)
 {
    stringstream ss;
    ss << "#define NLOHMANN_JSON_EXPAND( x ) x" << endl;
@@ -30,14 +34,75 @@ void build_code(int max_args)
        ss << "v" << i-1 << ")" << endl;
    }

-    cout << ss.str() << endl;
+    return ss.str();
+}
+
+// Builds the NLOHMANN_JSON_DOUBLE_PASTE dispatch table and recursive
+// definitions used by the *_WITH_NAMES macros. Its GET_MACRO dispatch reuses
+// the same max_args slots as NLOHMANN_JSON_PASTE, but DOUBLE_PASTE consumes
+// its arguments two at a time (name, member), so an even slot count falls
+// back to the next lower odd NLOHMANN_JSON_DOUBLE_PASTE<N>.
+string build_double_paste_code(int max_args)
+{
+    stringstream ss;
+    ss << "#define NLOHMANN_JSON_DOUBLE_PASTE(...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \\" << endl;
+    for (int i = max_args ; i > 1 ; i--)
+    {
+        int k = (i % 2 == 1) ? i : i - 1;
+        ss << "NLOHMANN_JSON_DOUBLE_PASTE" << k << ", \\" << endl;
+    }
+    ss << "NLOHMANN_JSON_DOUBLE_PASTE1)(__VA_ARGS__))" << endl;
+
+    ss << "#define NLOHMANN_JSON_DOUBLE_PASTE3(func, v1, v2) func(v1, v2)" << endl;
+    for (int k = 5 ; k <= max_args - 1 ; k += 2)
+    {
+        ss << "#define NLOHMANN_JSON_DOUBLE_PASTE" << k << "(func, ";
+        for (int j = 1 ; j < k - 1 ; j++)
+            ss << "v" << j << ", ";
+        ss << "v" << k - 1 << ") NLOHMANN_JSON_DOUBLE_PASTE3(func, v1, v2) NLOHMANN_JSON_DOUBLE_PASTE" << k - 2 << "(func, ";
+        for (int j = 3 ; j < k - 1 ; j++)
+            ss << "v" << j << ", ";
+        ss << "v" << k - 1 << ")" << endl;
+    }
+
+    return ss.str();
+}
+
+// Builds the NLOHMANN_JSON_TYPE_BODY dispatch table: max_args - 1 slots
+// selecting the *_MEMBERS implementation and a final slot selecting
+// *_EMPTY, so NLOHMANN_DEFINE_TYPE_*(Type) with no further arguments still
+// resolves (issue #4041).
+string build_type_body_table(int max_args)
+{
+    stringstream ss;
+    ss << "#define NLOHMANN_JSON_TYPE_BODY(Prefix, ...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \\" << endl;
+    const int per_line = 8;
+    for (int i = 1 ; i <= max_args ; i++)
+    {
+        ss << (i == max_args ? "Prefix ## EMPTY" : "Prefix ## MEMBERS") << ", ";
+        if (i % per_line == 0)
+            ss << "\\" << endl;
+    }
+    ss << "NLOHMANN_JSON_TYPE_BODY_SENTINEL))" << endl;
+
+    return ss.str();
 }

 int main(int argc, char** argv)
 {
    int max_args = 64;
-    build_code(max_args);
+
+    // With "type_body", print only the NLOHMANN_JSON_TYPE_BODY dispatch
+    // table (a separate insertion point in macro_scope.hpp); otherwise
+    // print the EXPAND/GET_MACRO/PASTE/DOUBLE_PASTE block that precedes it.
+    if (argc > 1 && string(argv[1]) == "type_body")
+    {
+        cout << build_type_body_table(max_args);
+    }
+    else
+    {
+        cout << build_paste_code(max_args) << build_double_paste_code(max_args);
+    }

    return 0;
 }
-
@@ -5,6 +5,8 @@ import logging
 import os
 import re
 import shutil
+import socket
+import ssl
 import sys
 import subprocess

@@ -34,7 +36,7 @@ JSON_VERSION_RE = re.compile(r'\s*#\s*define\s+NLOHMANN_JSON_VERSION_MAJOR\s+')

 class ExitHandler(logging.StreamHandler):
    def __init__(self, level):
-        """."""
+        """Exit the process on log records at or above level."""
        super().__init__()
        self.level = level

@@ -54,7 +56,7 @@ def is_project_root(test_dir='.'):

 class DirectoryEventBucket:
    def __init__(self, callback, delay=1.2, threshold=0.8):
-        """."""
+        """Batch directory events and pass their common path to callback."""
        self.delay = delay
        self.threshold = timedelta(seconds=threshold)
        self.callback = callback
@@ -99,7 +101,7 @@ class WorkTree:
    make_command = 'make'

    def __init__(self, root_dir, tree_dir):
-        """."""
+        """Track the working tree at tree_dir and its amalgamated header."""
        self.root_dir = root_dir
        self.tree_dir = tree_dir
        self.rel_dir = os.path.relpath(tree_dir, root_dir)
@@ -114,11 +116,11 @@ class WorkTree:
        self.build_time = t.strftime(DATETIME_FORMAT)

    def __hash__(self):
-        """."""
+        """Hash by working tree directory."""
        return hash((self.tree_dir))

    def __eq__(self, other):
-        """."""
+        """Compare by working tree directory."""
        if not isinstance(other, type(self)):
            return NotImplemented
        return self.tree_dir == other.tree_dir
@@ -150,7 +152,7 @@ class WorkTree:

 class WorkTrees(FileSystemEventHandler):
    def __init__(self, root_dir):
-        """."""
+        """Find the working trees below root_dir and watch it for changes."""
        super().__init__()
        self.root_dir = root_dir
        self.trees = set([])
@@ -250,11 +252,11 @@ class WorkTrees(FileSystemEventHandler):
        self.observer.stop()
        self.observer.join()

-class HeaderRequestHandler(SimpleHTTPRequestHandler): # lgtm[py/missing-call-to-init]
+class HeaderRequestHandler(SimpleHTTPRequestHandler):
    cors_origins = DEFAULT_CORS_ORIGINS

    def __init__(self, request, client_address, server):
-        """."""
+        """Handle a request for a header below the working trees' root directory."""
        self.worktrees = server.worktrees
        self.worktree = None
        try:
@@ -336,7 +338,7 @@ class HeaderRequestHandler(SimpleHTTPRequestHandler): # lgtm[py/missing-call-to-

 class DualStackServer(ThreadingHTTPServer):
    def __init__(self, addr, worktrees):
-        """."""
+        """Serve the headers of worktrees on addr."""
        self.worktrees = worktrees
        super().__init__(addr, HeaderRequestHandler)

@@ -349,8 +351,6 @@ class DualStackServer(ThreadingHTTPServer):

 if __name__ == '__main__':
    import argparse
-    import ssl
-    import socket
    import yaml

    # exit code
				`@@ -1 +0,0 @@`
				`<a target="_blank" href="https://wandbox.org/permlink/hUJYo1HWmfTBLMGn"><b>online</b></a>`