create objects for tokens that cannot be array indices (#5357 )

When operator[](json_pointer) traverses a level that does not exist yet, the null value is turned into an array or an object depending on the reference token. The check only tested whether all characters are digits, so tokens that can never be a valid array index selected an array and then failed: - "01" (and any other token with a leading '0') threw parse_error.106 - the empty token threw out_of_range.404 Both tokens are valid object keys, and both work when the level already exists as an object, so creating the level changed the outcome. Test the token against the RFC 6901, Sect. 4 grammar for array indices instead, so that such tokens create an object. This only affects pointers that threw before. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-08-28 20:07:32 +00:00 · 2026-08-04 08:51:54 +02:00
47 changed files with 202 additions and 715 deletions
@@ -11,7 +11,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -34,7 +34,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -67,18 +67,8 @@ jobs:
          ${{ github.workspace }}/venv/bin/astyle --project=tools/astyle/.astylerc --suffix=none --quiet \
            $INCLUDE_DIR/json.hpp $INCLUDE_DIR/json_fwd.hpp

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

      - name: Build patch and check for differences
        id: diff
@@ -9,7 +9,7 @@ jobs:
    runs-on: ubuntu-22.04
    steps:
    - name: Harden Runner
-      uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+      uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
      with:
        egress-policy: audit

@@ -27,7 +27,7 @@ jobs:

    steps:
    - name: Harden Runner
-      uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+      uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
      with:
        egress-policy: audit

@@ -38,14 +38,14 @@ jobs:

    # Initializes the CodeQL tools for scanning.
    - name: Initialize CodeQL
-      uses: github/codeql-action/init@db488ddef3bf6cb639b32c2e9a7c0a7ea8271d28 # v4.37.8
+      uses: github/codeql-action/init@e4fba868fa4b1b91e1fdab776edc8cfbe6e9fb81 # v4.37.3
      with:
        languages: c-cpp

    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
    # If this step fails, then you should remove it and run the build manually (see below)
    - name: Autobuild
-      uses: github/codeql-action/autobuild@db488ddef3bf6cb639b32c2e9a7c0a7ea8271d28 # v4.37.8
+      uses: github/codeql-action/autobuild@e4fba868fa4b1b91e1fdab776edc8cfbe6e9fb81 # v4.37.3

    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@db488ddef3bf6cb639b32c2e9a7c0a7ea8271d28 # v4.37.8
+      uses: github/codeql-action/analyze@e4fba868fa4b1b91e1fdab776edc8cfbe6e9fb81 # v4.37.3
@@ -19,7 +19,7 @@ jobs:
      pull-requests: write
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -17,7 +17,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -27,7 +27,7 @@ jobs:
      security-events: write
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

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

      - name: Upload analysis results to GitHub Security tab
-        uses: github/codeql-action/upload-sarif@db488ddef3bf6cb639b32c2e9a7c0a7ea8271d28 # v4.37.8
+        uses: github/codeql-action/upload-sarif@e4fba868fa4b1b91e1fdab776edc8cfbe6e9fb81 # v4.37.3
        with:
          sarif_file: ${{github.workspace}}/flawfinder_results.sarif
@@ -17,7 +17,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -7,6 +7,7 @@ on:
      - develop
    paths:
      - docs/mkdocs/**
+      - docs/examples/**
  workflow_dispatch:

 # we don't want to have concurrent jobs, and we don't want to cancel running jobs to avoid broken publications
@@ -26,7 +27,7 @@ jobs:
    runs-on: ubuntu-22.04
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -36,7 +36,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -76,6 +76,6 @@ jobs:

      # Upload the results to GitHub's code scanning dashboard.
      - name: "Upload to code-scanning"
-        uses: github/codeql-action/upload-sarif@db488ddef3bf6cb639b32c2e9a7c0a7ea8271d28 # v4.37.8
+        uses: github/codeql-action/upload-sarif@e4fba868fa4b1b91e1fdab776edc8cfbe6e9fb81 # v4.37.3
        with:
          sarif_file: results.sarif
@@ -32,7 +32,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

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

      # Upload SARIF file generated in previous step
      - name: Upload SARIF file
-        uses: github/codeql-action/upload-sarif@db488ddef3bf6cb639b32c2e9a7c0a7ea8271d28 # v4.37.8
+        uses: github/codeql-action/upload-sarif@e4fba868fa4b1b91e1fdab776edc8cfbe6e9fb81 # v4.37.3
        with:
          sarif_file: semgrep.sarif
        if: always()
@@ -16,7 +16,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -25,7 +25,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -35,7 +35,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -47,7 +47,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -60,7 +60,7 @@ jobs:
        target: [ci_test_amalgamation, ci_test_single_header, ci_cppcheck, ci_cpplint, ci_reproducible_tests, ci_non_git_tests, ci_offline_testdata, ci_reuse_compliance, ci_test_valgrind]
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -70,7 +70,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -89,7 +89,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -108,7 +108,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -118,7 +118,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -184,7 +184,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: CXX=g++-${{ matrix.compiler }} cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -202,7 +202,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -212,14 +212,14 @@ jobs:
    runs-on: ubuntu-latest
    strategy:
      matrix:
-        compiler: ['3.4', '3.5', '3.6', '3.7', '3.8', '3.9', '4', '5', '6', '7', '8', '9', '10', '11', '12', '13', '14', '15-bullseye', '16', '17', '18', '19', '20', '21', '22', 'latest']
+        compiler: ['3.4', '3.5', '3.6', '3.7', '3.8', '3.9', '4', '5', '6', '7', '8', '9', '10', '11', '12', '13', '14', '15-bullseye', '16', '17', '18', '19', '20', 'latest']
    container: silkeh/clang:${{ matrix.compiler }}
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Set env FORCE_STDCPPFS_FLAG for clang 7 / 8 / 9 / 10
        run: echo "JSON_FORCED_GLOBAL_COMPILE_OPTIONS=-DJSON_HAS_FILESYSTEM=0;-DJSON_HAS_EXPERIMENTAL_FILESYSTEM=0" >> "$GITHUB_ENV"
        if: ${{ matrix.compiler == '7' || matrix.compiler == '8' || matrix.compiler == '9' || matrix.compiler == '10' }}
@@ -239,7 +239,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -259,7 +259,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build with libc++
@@ -286,7 +286,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -306,7 +306,7 @@ jobs:
      # import-std support. Its opt-in token is CMake-version-specific, so pin
      # CMake to the version whose token is set in tests/module_cpp20/CMakeLists.txt.
      - name: Get pinned CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
        with:
          cmakeVersion: 4.3.4
      # Clang: the std library module is provided by libc++ (the image's libstdc++
@@ -332,7 +332,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -347,7 +347,7 @@ jobs:
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -359,7 +359,7 @@ jobs:
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DJSON_CI=On
      - name: Build
@@ -369,7 +369,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -379,7 +379,7 @@ jobs:
        with:
          persist-credentials: false
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Run CMake
        run: cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=$EMSDK/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake -GNinja
      - name: Build
@@ -392,7 +392,7 @@ jobs:
        target: [ci_test_examples, ci_test_build_documentation]
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
        with:
          egress-policy: audit

@@ -88,7 +88,7 @@ jobs:
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
      - name: Set extra CXX_FLAGS for latest std_version
        # /wd5285 silences C5285 emitted by the bundled third-party doctest.h, which
        # specializes std::tuple (newly diagnosed by the VS2026 v145 toolset)
@@ -153,16 +153,10 @@ jobs:
        with:
          platform: x64
          version: 12.2.0 # https://github.com/egor-tensin/setup-mingw/issues/14
-      # CMAKE_CXX_FLAGS_DEBUG is overridden to drop the default -g: linking
-      # test-regression2_cpp20 intermittently fails with "relocation truncated
-      # to fit: IMAGE_REL_AMD64_SECREL against `.debug_line'" because the
-      # MinGW linker cannot relocate the debug sections this test produces.
-      # The tests are only built and run here, so the debug info is not used.
      - name: Run CMake
        run: cmake -S . -B build ^
             -DCMAKE_CXX_COMPILER="C:/Program Files/LLVM/bin/clang++.exe" ^
             -DCMAKE_CXX_FLAGS="--target=x86_64-w64-mingw32 -stdlib=libstdc++ -pthread" ^
-             -DCMAKE_CXX_FLAGS_DEBUG="-g0" ^
             -DCMAKE_EXE_LINKER_FLAGS="-lwinpthread" ^
             -G"MinGW Makefiles" ^
             -DCMAKE_BUILD_TYPE=Debug ^
@@ -199,7 +193,7 @@ jobs:
      # import-std support. Its opt-in token is CMake-version-specific, so pin
      # CMake to the version whose token is set in tests/module_cpp20/CMakeLists.txt.
      - name: Get pinned CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
+        uses: lukka/get-cmake@e6906078ebd1ccb8ce51ab4626ac46a1b5a517e3 # v4.4.0
        with:
          cmakeVersion: 4.3.4
      - name: Run CMake (Debug)
@@ -42,7 +42,6 @@
  - [Specializing enum conversion](#specializing-enum-conversion)
  - [Binary formats (BSON, CBOR, MessagePack, UBJSON, and BJData)](#binary-formats-bson-cbor-messagepack-ubjson-and-bjdata)
 - [Customers](#customers)
- [Ecosystem](#ecosystem)
 - [Supported compilers](#supported-compilers)
 - [Integration](#integration)
  - [CMake](#cmake)
@@ -1187,11 +1186,6 @@ The library is used in multiple projects, applications, operating systems, etc.

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

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

 Though it's 2026 already, the support for C++11 is still a bit sparse. Currently, the following compilers are known to work:
@@ -294,7 +294,7 @@ file(GLOB_RECURSE INDENT_FILES
        ${PROJECT_SOURCE_DIR}/tests/src/*.cpp
        ${PROJECT_SOURCE_DIR}/tests/src/*.hpp
        ${PROJECT_SOURCE_DIR}/tests/benchmarks/src/benchmarks.cpp
-    ${PROJECT_SOURCE_DIR}/docs/mkdocs/docs/examples/*.cpp
+    ${PROJECT_SOURCE_DIR}/docs/examples/*.cpp
 )

 set(include_dir ${PROJECT_SOURCE_DIR}/single_include/nlohmann)
@@ -128,10 +128,13 @@ Strong exception safety: if an exception occurs, the original value stays intact

        When the JSON pointer traverses intermediate levels that don't exist at all yet (not just a missing
        leaf), each missing level is created as an array or an object depending on whether the corresponding
-        pointer token parses as a non-negative integer: a numeric token creates an array, a non-numeric token
-        creates an object. For example, on an initially `#!json null` value, `/foo/0/0/0` creates nested arrays,
-        while `/foo/one/one/one` creates nested objects. This is not specified by the JSON Pointer RFC; it is
-        this library's own, intentional disambiguation rule. See also [JSON Pointer](../../features/json_pointer.md).
+        pointer token is a valid array index: a token that is a nonempty sequence of digits without a leading
+        `0` (or the token `-`) creates an array, and every other token creates an object. For example, on an
+        initially `#!json null` value, `/foo/0/0/0` creates nested arrays, while `/foo/one/one/one` creates
+        nested objects. Tokens such as `01` or the empty token cannot be array indices (cf. RFC 6901, Sect. 4)
+        and therefore create objects, just as they would if the level already existed as an object. This is not
+        specified by the JSON Pointer RFC; it is this library's own, intentional disambiguation rule. See also
+        [JSON Pointer](../../features/json_pointer.md).

 ## Examples

@@ -52,11 +52,6 @@ optional, `#!cpp bjdata_version_t::draft2` by default.

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

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

 Linear in the size of the JSON value `j`.
@@ -46,9 +46,7 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va

 ## Complexity

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

 ## Examples

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

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

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

 Linear in the size of the JSON value `j`.
@@ -1,40 +0,0 @@
-# Ecosystem
-
-The projects below build on top of `nlohmann::json` rather than merely using it - schema validators, language
-bindings, format converters, and similar building blocks. The list is not exhaustive, and is curated rather than
-automatically generated. If you maintain or know of a project that belongs here,
-[please let me know](mailto:mail@nlohmann.me).
-
-For products, applications, and organizations that use the library, see [Customers](../home/customers.md) instead.
-
-## Schema validation
-
- [**json-schema-validator**](https://github.com/pboettch/json-schema-validator), a JSON Schema (draft 7) validator
-  with human-readable error messages
-
-## Serialization and reflection
-
- [**nlohmann_json_reflect**](https://github.com/1261385937/nlohmann_json_reflect), a reflection extension for
-  (de)serializing nested containers-in-structs-in-containers
-
-## Encodings
-
- [**base-encode-decode**](https://github.com/saxonnicholls/base-encode-decode), a header-only Base64/32/16/8/4/2
-  (and DNA/RNA) encoding library, with an adapter that serializes binary data through `nlohmann::json`
-
-## Language bindings and interop
-
- [**pybind11_json**](https://github.com/pybind/pybind11_json), a bidirectional type caster between
-  `nlohmann::json` and Python objects for [pybind11](https://github.com/pybind/pybind11) bindings
- [**nanobind_json**](https://github.com/ianhbell/nanobind_json), the same idea for
-  [nanobind](https://github.com/wjakob/nanobind) bindings
- [**nlohmann_json_qt**](https://github.com/dpurgin/nlohmann_json_qt), deserialization helpers for Qt types
-  (`QString`, `QUrl`, `QDateTime`, `QVector`, ...) from `nlohmann::json`
- [**vulkan2json**](https://github.com/Fadis/vulkan2json), serialization and deserialization of Vulkan API structs
-
-## Format converters
-
- [**tojson**](https://github.com/mircodz/tojson), a header-only converter between YAML/XML documents and
-  `nlohmann::json`
- [**json2xml**](https://github.com/testillano/json2xml), a header-only converter from `nlohmann::json` to XML for
-  simple configuration documents
@@ -1,6 +1,5 @@
 # Community

- [Ecosystem](ecosystem.md) - third-party projects built on top of this library
 - [Code of Conduct](code_of_conduct.md) - the rules and norms of this project
 - [Contribution Guidelines](contribution_guidelines.md) - guidelines how to contribute to this project
 - [Governance](governance.md) - the governance model of this project
@@ -66,7 +66,6 @@ Note: Some modern features (like C++20 ranges or filesystem support) may be disa
        | Clang 20.1.1                                 | x86_64       | Ubuntu 22.04.1 LTS                | GitHub    |
        | Clang 20.1.8 with GNU-like command-line      | x86_64       | Windows Server 2022 (Build 20348) | GitHub    |
        | Clang 21.1.8                                 | x86_64       | Ubuntu 22.04.1 LTS                | GitHub    |
-        | Clang 22.1.8                                 | x86_64       | Ubuntu 22.04.1 LTS                | GitHub    |
        | CUDA 11.8.0 (nvcc)                           | x86_64       | Ubuntu 22.04 LTS                  | GitHub    |
        | CUDA 12.1.1 (nvcc)                           | x86_64       | Ubuntu 22.04 LTS                  | GitHub    |
        | CUDA 12.6.3 (nvcc)                           | x86_64       | Ubuntu 22.04 LTS                  | GitHub    |
@@ -9,13 +9,13 @@ int main()
    auto text = R"({"IDs": [116, 943], "Width": 800})";

    // discard the array when the parser reads its opening bracket
-    json j_array_start = json::parse(text, [](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
+    json j_array_start = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & /*parsed*/)
    {
        return event != json::parse_event_t::array_start;
    });

    // discard the same array when the parser reads its closing bracket
-    json j_array_end = json::parse(text, [](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
+    json j_array_end = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & /*parsed*/)
    {
        return event != json::parse_event_t::array_end;
    });
@@ -33,7 +33,7 @@ int main()
    });

    // discard the top-level object
-    json j_root = json::parse(text, [](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
+    json j_root = json::parse(text, [](int /*depth*/, json::parse_event_t event, json & /*parsed*/)
    {
        return event != json::parse_event_t::object_end;
    });
@@ -116,19 +116,9 @@ The library uses the following mapping from JSON values types to BJData types ac
    ```

    Likewise, when a JSON object in the above form is serialized using
-    [`to_bjdata`](../../api/basic_json/to_bjdata.md), it is automatically converted into a compact BJData ND-array. When
-    the 1-dimensional vector stored in `"_ArraySize_"` contains a single integer or two integers with one being 1, a
-    regular 1-D optimized array is generated instead.
-
-    An object is only converted if the annotation actually describes a packed array; otherwise it is serialized as a
-    regular JSON object. This requires all of the following:
-
-    - `"_ArrayType_"` is one of `uint8`, `int8`, `uint16`, `int16`, `uint32`, `int32`, `uint64`, `int64`, `single`,
-      `double`, `char`, or `byte`,
-    - every entry of `"_ArraySize_"` is a non-negative integer, and their product is representable as a `std::size_t`,
-    - `"_ArrayData_"` holds exactly that many elements, and
-    - every element of `"_ArrayData_"` is a number of the kind named by `"_ArrayType_"` (a floating-point number for
-      `single` and `double`, an integer otherwise).
+    [`to_bjdata`](../../api/basic_json/to_bjdata.md), it is automatically converted into a compact BJData ND-array. The
+    only exception is, that when the 1-dimensional vector stored in `"_ArraySize_"` contains a single integer or two
+    integers with one being 1, a regular 1-D optimized array is generated.

    The current version of this library does not yet support automatic detection of and conversion from a nested JSON
    array input to a BJData ND-array.
@@ -98,17 +98,6 @@ The library maps BSON record types to JSON value types as follows:
    This library deserializes BSON type `0x11` (Timestamp) as a `number_unsigned` value. The 64-bit value is preserved,
    but the Timestamp type information is not.

-!!! warning "Lenient BSON input handling"
-
-    The BSON reader is lenient in a few areas where the BSON specification is more restrictive:
-
-    - array element keys are not checked against the required decimal sequence (`0`, `1`, `2`, ...),
-    - any non-zero byte is accepted as `true` for the boolean type, and
-    - the payload for binary subtype `0x02` is returned as-is, including its inner length prefix.
-
-    If BSON input must be validated for strict specification compliance, validate it separately before passing it to
-    `from_bson()`.
-
 ??? example

    ```cpp
@@ -160,11 +160,14 @@ The library maps CBOR types to JSON value types as follows:

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

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

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

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

 !!! warning "Tagged items"

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

 ??? example

@@ -54,30 +54,6 @@ json j = {1.0, "hello", 42};
 auto t = j.get<std::tuple<double, std::string, int>>();  // {1.0, "hello", 42}
 ```

-!!! warning "Serializing a `std::pair`/`std::tuple` whose every element is a string-keyed pair"
-
-    When *every* element of a `#!cpp std::pair` or `#!cpp std::tuple` is itself a two-element array whose first
-    element is a string (for example `#!cpp std::pair<std::string, int>`), serializing it produces a JSON **object**
-    instead of the expected array:
-
-    ```cpp
-    using kv = std::pair<std::string, int>;
-    json j = std::pair<kv, kv>{{"a", 1}, {"b", 2}};  // {"a":1,"b":2}, not [["a",1],["b",2]]
-    ```
-
-    This is a consequence of the [brace-initializer object-detection rule](creating_values.md): the same rule that
-    lets `#!cpp json{{"a", 1}, {"b", 2}}` create an object also fires here. The resulting object cannot be read back
-    into the original type (`#!cpp get<std::pair<kv, kv>>()` throws [`type_error.302`](../home/exceptions.md#jsonexceptiontype_error302)),
-    and duplicate keys collapse into one, losing elements. This only affects `#!cpp std::pair`/`#!cpp std::tuple`
-    themselves; a `#!cpp std::vector<std::pair<std::string, int>>`, or a pair/tuple with at least one element that is
-    not a string-keyed pair, serializes to an array as expected. To force an array, build one explicitly from the
-    elements with [`array`](../api/basic_json/array.md):
-
-    ```cpp
-    std::pair<kv, kv> p{{"a", 1}, {"b", 2}};
-    json a = json::array({p.first, p.second});  // [["a",1],["b",2]]
-    ```
-
 !!! info "Extracting references into a tuple"

    A tuple type may also hold references (e.g. `#!cpp std::tuple<double&, std::string&>`) to avoid copying: `get`
@@ -965,19 +965,3 @@ A JSON Patch operation 'test' failed. The unsuccessful operation is also printed
    ```
    [json.exception.other_error.501] unsuccessful: {"op":"test","path":"/baz","value":"bar"}
    ```
-
-### json.exception.other_error.502
-
-[`to_ubjson`](../api/basic_json/to_ubjson.md) and [`to_bjdata`](../api/basic_json/to_bjdata.md) were called with
-`use_type = true` but `use_size = false`. UBJSON requires a size marker (`#`) after a type marker (`$`).
-
-!!! failure "Example message"
-
-    ```
-    [json.exception.other_error.502] use_type requires use_size = true
-    ```
-
-!!! note
-
-    This exception was added in version 3.13.0. Before that, debug builds aborted on an assertion and release builds
-    wrote a `$` marker without `#`, which [`from_ubjson`](../api/basic_json/from_ubjson.md) then rejected.
@@ -308,7 +308,6 @@ nav:
          - 'NLOHMANN_JSON_VERSION_MAJOR, NLOHMANN_JSON_VERSION_MINOR, NLOHMANN_JSON_VERSION_PATCH': api/macros/nlohmann_json_version_major.md
  - Community:
      - community/index.md
-      - community/ecosystem.md
      - "Code of Conduct": community/code_of_conduct.md
      - community/contribution_guidelines.md
      - community/quality_assurance.md
@@ -1,4 +1,4 @@
-wheel==0.48.0
+wheel==0.47.0

 mkdocs==1.6.1                                       # documentation framework
 mkdocs-git-revision-date-localized-plugin==1.5.3    # plugin "git-revision-date-localized"
@@ -465,6 +465,15 @@ class binary_reader
    // CBOR //
    //////////

+    /*!
+    @param[in] get_char  whether a new character should be retrieved from the
+                         input (true) or whether the last read character should
+                         be considered instead (false)
+    @param[in] tag_handler how CBOR tags should be treated
+
+    @return whether a valid CBOR value was passed to the SAX parser
+    */
+
    template<typename NumberType>
    bool get_cbor_negative_integer()
    {
@@ -483,14 +492,6 @@ class binary_reader
        return sax->number_integer(static_cast<number_integer_t>(-1) - static_cast<number_integer_t>(number));
    }

-    /*!
-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true) or whether the last read character should
-                         be considered instead (false)
-    @param[in] tag_handler how CBOR tags should be treated
-
-    @return whether a valid CBOR value was passed to the SAX parser
-    */
    bool parse_cbor_internal(const bool get_char,
                             const cbor_tag_handler_t tag_handler)
    {
@@ -773,13 +774,7 @@ class binary_reader
            case 0xBF: // map (indefinite length)
                return get_cbor_object(detail::unknown_size(), tag_handler);

-            case 0xC0: // tagged item
-            case 0xC1:
-            case 0xC2:
-            case 0xC3:
-            case 0xC4:
-            case 0xC5:
-            case 0xC6:
+            case 0xC6: // tagged item
            case 0xC7:
            case 0xC8:
            case 0xC9:
@@ -794,9 +789,6 @@ class binary_reader
            case 0xD2:
            case 0xD3:
            case 0xD4:
-            case 0xD5:
-            case 0xD6:
-            case 0xD7:
            case 0xD8: // tagged item (1 byte follows)
            case 0xD9: // tagged item (2 bytes follow)
            case 0xDA: // tagged item (4 bytes follow)
@@ -1996,11 +1988,7 @@ class binary_reader
    {
        if (get_char)
        {
-            // no get_ignore_noop() here: the byte read next must be a string
-            // length type specification, and a no-op ('N') is not valid in
-            // that position. No-ops at positions where a value may appear are
-            // already consumed by the callers via get_ignore_noop().
-            get();
+            get();  // TODO(niels): may we ignore N here?
        }

        if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format, "value")))
@@ -345,12 +345,8 @@ struct wide_string_input_helper<BaseInputAdapter, 4>
            }
            else
            {
-                // A code point above U+10FFFF has no UTF-8 encoding. Passing the
-                // unit through would narrow it to int, where 0xFFFFFFFF becomes
-                // char_traits<char>::eof() and would end the input silently, so
-                // emit a byte that is never valid UTF-8 and let the decoder
-                // reject it.
-                utf8_bytes[0] = 0xFF;
+                // unknown character
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
                utf8_bytes_filled = 1;
            }
        }
@@ -370,10 +370,8 @@ class json_sax_dom_parser

                case value_t::string:
                {
-                    // escape sequences make the token longer than the value it
-                    // parses to, so the start position cannot be derived from
-                    // the value; use the offset the lexer recorded instead
-                    v.start_position = m_lexer_ref->get_token_start_position();
+                    // include the length of the quotes, which is 2
+                    v.start_position = v.end_position - v.m_data.m_value.string->size() - 2;
                    break;
                }

@@ -771,10 +769,8 @@ class json_sax_dom_callback_parser

                case value_t::string:
                {
-                    // escape sequences make the token longer than the value it
-                    // parses to, so the start position cannot be derived from
-                    // the value; use the offset the lexer recorded instead
-                    v.start_position = m_lexer_ref->get_token_start_position();
+                    // include the length of the quotes, which is 2
+                    v.start_position = v.end_position - v.m_data.m_value.string->size() - 2;
                    break;
                }

@@ -1357,11 +1357,6 @@ scan_number_done:
        token_buffer.clear();
        decimal_point_position = std::string::npos;

-#if JSON_DIAGNOSTIC_POSITIONS
-        // the first character of the token has already been read, hence the -1
-        token_start_position = position.chars_read_total - 1;
-#endif
-
        note_token_start(std::integral_constant<bool, lazy_token_string> {});
    }

@@ -1524,15 +1519,6 @@ scan_number_done:
        return position;
    }

-#if JSON_DIAGNOSTIC_POSITIONS
-    /// return the offset of the first character of the last read token; unlike
-    /// the token's parsed value, this accounts for escape sequences
-    constexpr std::size_t get_token_start_position() const noexcept
-    {
-        return token_start_position;
-    }
-#endif
-
    /// seekable adapter: rebuild the last read token from the input on demand
    const std::vector<char_type>& collect_token_chars(std::vector<char_type>& out, std::true_type /*lazy*/) const
    {
@@ -1733,12 +1719,6 @@ scan_number_done:
    /// the last read token on error for seekable adapters (see collect_token_chars)
    std::size_t token_string_start = 0;

-#if JSON_DIAGNOSTIC_POSITIONS
-    /// start offset of the current token within the input, used to report
-    /// diagnostic positions (see reset())
-    std::size_t token_start_position = 0;
-#endif
-
    /// buffer for variable-length tokens (numbers, strings)
    string_t token_buffer {};

@@ -396,15 +396,19 @@ class json_pointer
            // convert null values to arrays or objects before continuing
            if (ptr->is_null())
            {
-                // check if the reference token is a number
-                const bool nums =
-                    std::all_of(reference_token.begin(), reference_token.end(),
-                                [](const unsigned char x)
+                // check if the reference token is a valid array index, that is
+                // a nonempty sequence of digits without a leading '0'
+                // (cf. RFC 6901, Sect. 4); tokens that could never be a valid
+                // array index (such as "01" or "") are treated as object keys
+                const bool nums = !reference_token.empty()
+                                  && (reference_token.size() == 1 || reference_token[0] != '0')
+                                  && std::all_of(reference_token.begin(), reference_token.end(),
+                                                 [](const unsigned char x)
                {
                    return std::isdigit(x);
                });

-                // change value to an array for numbers or "-" or to object otherwise
+                // change value to an array for array indices or "-" or to object otherwise
                *ptr = (nums || reference_token == "-")
                       ? detail::value_t::array
                       : detail::value_t::object;
@@ -813,10 +813,7 @@ class binary_writer
                bool prefix_required = true;
                if (use_type && !j.m_data.m_value.array->empty())
                {
-                    if (!use_count)
-                    {
-                        JSON_THROW(other_error::create(502, "use_type requires use_size = true", &j));
-                    }
+                    JSON_ASSERT(use_count);
                    const CharType first_prefix = ubjson_prefix(j.front(), use_bjdata);
                    const bool same_prefix = std::all_of(j.begin() + 1, j.end(),
                                                         [this, first_prefix, use_bjdata](const BasicJsonType & v)
@@ -862,10 +859,7 @@ class binary_writer

                if (use_type && (bjdata_draft3 || !j.m_data.m_value.binary->empty()))
                {
-                    if (!use_count)
-                    {
-                        JSON_THROW(other_error::create(502, "use_type requires use_size = true", &j));
-                    }
+                    JSON_ASSERT(use_count);
                    oa->write_character(to_char_type('$'));
                    oa->write_character(bjdata_draft3 ? 'B' : 'U');
                }
@@ -917,10 +911,7 @@ class binary_writer
                bool prefix_required = true;
                if (use_type && !j.m_data.m_value.object->empty())
                {
-                    if (!use_count)
-                    {
-                        JSON_THROW(other_error::create(502, "use_type requires use_size = true", &j));
-                    }
+                    JSON_ASSERT(use_count);
                    const CharType first_prefix = ubjson_prefix(j.front(), use_bjdata);
                    const bool same_prefix = std::all_of(j.begin(), j.end(),
                                                         [this, first_prefix, use_bjdata](const BasicJsonType & v)
@@ -1679,23 +1670,7 @@ class binary_writer
            {
                return true;
            }
-
-            // a dimension that does not fit into std::size_t, or a product that
-            // overflows it, would wrap around and could match the size of
-            // _ArrayData_ by accident; the resulting header announces an
-            // element count that no reader can honor (the binary reader rejects
-            // it with out_of_range.408), so encode as a plain object instead
-            const auto dim = el.template get<std::uint64_t>();
-            if (!value_in_range_of<std::size_t>(dim))
-            {
-                return true;
-            }
-            const auto dim_size = static_cast<std::size_t>(dim);
-            if (dim_size != 0 && len > (std::numeric_limits<std::size_t>::max)() / dim_size)
-            {
-                return true;
-            }
-            len *= dim_size;
+            len *= static_cast<std::size_t>(el.template get<std::uint64_t>());
        }

        key = "_ArrayData_";
@@ -3516,10 +3516,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
            if (merge_objects && it.value().is_object())
            {
                auto it2 = m_data.m_value.object->find(it.key());
-                // Only recurse when the existing value is itself an object.
-                // Otherwise overwrite, matching the documented "all other values
-                // are overwritten as usual" behavior (see #5402).
-                if (it2 != m_data.m_value.object->end() && it2->second.is_object())
+                if (it2 != m_data.m_value.object->end())
                {
                    it2->second.update(it.value(), true);
 #if JSON_DIAGNOSTICS
@@ -3655,12 +3652,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    // note parentheses around operands are necessary; see
    // https://github.com/nlohmann/json/issues/1530
-    // Mixed signed/unsigned integer comparisons check whether the signed value
-    // is negative before casting. If it is, the comparison is performed with
-    // the fixed values -1 and 1, which preserves the ordering relationship
-    // because any negative signed value is smaller than any unsigned value.
-    // Otherwise, the non-negative signed value is cast to unsigned before the
-    // comparison to avoid wraparound.
 #define JSON_IMPLEMENT_OPERATOR(op, null_result, unordered_result, default_result)                       \
    const auto lhs_type = lhs.type();                                                                    \
    const auto rhs_type = rhs.type();                                                                    \
@@ -3719,16 +3710,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    }                                                                                                    \
    else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_integer)                \
    {                                                                                                    \
-        return (rhs.m_data.m_value.number_integer < 0)                                                   \
-               ? (number_integer_t(1) op number_integer_t(-1))                                           \
-               : (lhs.m_data.m_value.number_unsigned op static_cast<number_unsigned_t>(rhs.m_data.m_value.number_integer)); \
+        return static_cast<number_integer_t>(lhs.m_data.m_value.number_unsigned) op rhs.m_data.m_value.number_integer; \
    }                                                                                                    \
    else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_unsigned)                \
    {                                                                                                    \
-        return (lhs.m_data.m_value.number_integer < 0)                                                   \
-               ? (number_integer_t(-1) op number_integer_t(1))                                           \
-               : (static_cast<number_unsigned_t>(lhs.m_data.m_value.number_integer) op rhs.m_data.m_value.number_unsigned); \
-    }                                                                                             \
+        return lhs.m_data.m_value.number_integer op static_cast<number_integer_t>(rhs.m_data.m_value.number_unsigned); \
+    }                                                                                                    \
    else if(compares_unordered(lhs, rhs))\
    {\
        return (unordered_result);\
@@ -7348,12 +7348,8 @@ struct wide_string_input_helper<BaseInputAdapter, 4>
            }
            else
            {
-                // A code point above U+10FFFF has no UTF-8 encoding. Passing the
-                // unit through would narrow it to int, where 0xFFFFFFFF becomes
-                // char_traits<char>::eof() and would end the input silently, so
-                // emit a byte that is never valid UTF-8 and let the decoder
-                // reject it.
-                utf8_bytes[0] = 0xFF;
+                // unknown character
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
                utf8_bytes_filled = 1;
            }
        }
@@ -9075,11 +9071,6 @@ scan_number_done:
        token_buffer.clear();
        decimal_point_position = std::string::npos;

-#if JSON_DIAGNOSTIC_POSITIONS
-        // the first character of the token has already been read, hence the -1
-        token_start_position = position.chars_read_total - 1;
-#endif
-
        note_token_start(std::integral_constant<bool, lazy_token_string> {});
    }

@@ -9242,15 +9233,6 @@ scan_number_done:
        return position;
    }

-#if JSON_DIAGNOSTIC_POSITIONS
-    /// return the offset of the first character of the last read token; unlike
-    /// the token's parsed value, this accounts for escape sequences
-    constexpr std::size_t get_token_start_position() const noexcept
-    {
-        return token_start_position;
-    }
-#endif
-
    /// seekable adapter: rebuild the last read token from the input on demand
    const std::vector<char_type>& collect_token_chars(std::vector<char_type>& out, std::true_type /*lazy*/) const
    {
@@ -9451,12 +9433,6 @@ scan_number_done:
    /// the last read token on error for seekable adapters (see collect_token_chars)
    std::size_t token_string_start = 0;

-#if JSON_DIAGNOSTIC_POSITIONS
-    /// start offset of the current token within the input, used to report
-    /// diagnostic positions (see reset())
-    std::size_t token_start_position = 0;
-#endif
-
    /// buffer for variable-length tokens (numbers, strings)
    string_t token_buffer {};

@@ -9833,10 +9809,8 @@ class json_sax_dom_parser

                case value_t::string:
                {
-                    // escape sequences make the token longer than the value it
-                    // parses to, so the start position cannot be derived from
-                    // the value; use the offset the lexer recorded instead
-                    v.start_position = m_lexer_ref->get_token_start_position();
+                    // include the length of the quotes, which is 2
+                    v.start_position = v.end_position - v.m_data.m_value.string->size() - 2;
                    break;
                }

@@ -10234,10 +10208,8 @@ class json_sax_dom_callback_parser

                case value_t::string:
                {
-                    // escape sequences make the token longer than the value it
-                    // parses to, so the start position cannot be derived from
-                    // the value; use the offset the lexer recorded instead
-                    v.start_position = m_lexer_ref->get_token_start_position();
+                    // include the length of the quotes, which is 2
+                    v.start_position = v.end_position - v.m_data.m_value.string->size() - 2;
                    break;
                }

@@ -11087,6 +11059,15 @@ class binary_reader
    // CBOR //
    //////////

+    /*!
+    @param[in] get_char  whether a new character should be retrieved from the
+                         input (true) or whether the last read character should
+                         be considered instead (false)
+    @param[in] tag_handler how CBOR tags should be treated
+
+    @return whether a valid CBOR value was passed to the SAX parser
+    */
+
    template<typename NumberType>
    bool get_cbor_negative_integer()
    {
@@ -11105,14 +11086,6 @@ class binary_reader
        return sax->number_integer(static_cast<number_integer_t>(-1) - static_cast<number_integer_t>(number));
    }

-    /*!
-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true) or whether the last read character should
-                         be considered instead (false)
-    @param[in] tag_handler how CBOR tags should be treated
-
-    @return whether a valid CBOR value was passed to the SAX parser
-    */
    bool parse_cbor_internal(const bool get_char,
                             const cbor_tag_handler_t tag_handler)
    {
@@ -11395,13 +11368,7 @@ class binary_reader
            case 0xBF: // map (indefinite length)
                return get_cbor_object(detail::unknown_size(), tag_handler);

-            case 0xC0: // tagged item
-            case 0xC1:
-            case 0xC2:
-            case 0xC3:
-            case 0xC4:
-            case 0xC5:
-            case 0xC6:
+            case 0xC6: // tagged item
            case 0xC7:
            case 0xC8:
            case 0xC9:
@@ -11416,9 +11383,6 @@ class binary_reader
            case 0xD2:
            case 0xD3:
            case 0xD4:
-            case 0xD5:
-            case 0xD6:
-            case 0xD7:
            case 0xD8: // tagged item (1 byte follows)
            case 0xD9: // tagged item (2 bytes follow)
            case 0xDA: // tagged item (4 bytes follow)
@@ -12618,11 +12582,7 @@ class binary_reader
    {
        if (get_char)
        {
-            // no get_ignore_noop() here: the byte read next must be a string
-            // length type specification, and a no-op ('N') is not valid in
-            // that position. No-ops at positions where a value may appear are
-            // already consumed by the callers via get_ignore_noop().
-            get();
+            get();  // TODO(niels): may we ignore N here?
        }

        if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format, "value")))
@@ -15977,15 +15937,19 @@ class json_pointer
            // convert null values to arrays or objects before continuing
            if (ptr->is_null())
            {
-                // check if the reference token is a number
-                const bool nums =
-                    std::all_of(reference_token.begin(), reference_token.end(),
-                                [](const unsigned char x)
+                // check if the reference token is a valid array index, that is
+                // a nonempty sequence of digits without a leading '0'
+                // (cf. RFC 6901, Sect. 4); tokens that could never be a valid
+                // array index (such as "01" or "") are treated as object keys
+                const bool nums = !reference_token.empty()
+                                  && (reference_token.size() == 1 || reference_token[0] != '0')
+                                  && std::all_of(reference_token.begin(), reference_token.end(),
+                                                 [](const unsigned char x)
                {
                    return std::isdigit(x);
                });

-                // change value to an array for numbers or "-" or to object otherwise
+                // change value to an array for array indices or "-" or to object otherwise
                *ptr = (nums || reference_token == "-")
                       ? detail::value_t::array
                       : detail::value_t::object;
@@ -17756,10 +17720,7 @@ class binary_writer
                bool prefix_required = true;
                if (use_type && !j.m_data.m_value.array->empty())
                {
-                    if (!use_count)
-                    {
-                        JSON_THROW(other_error::create(502, "use_type requires use_size = true", &j));
-                    }
+                    JSON_ASSERT(use_count);
                    const CharType first_prefix = ubjson_prefix(j.front(), use_bjdata);
                    const bool same_prefix = std::all_of(j.begin() + 1, j.end(),
                                                         [this, first_prefix, use_bjdata](const BasicJsonType & v)
@@ -17805,10 +17766,7 @@ class binary_writer

                if (use_type && (bjdata_draft3 || !j.m_data.m_value.binary->empty()))
                {
-                    if (!use_count)
-                    {
-                        JSON_THROW(other_error::create(502, "use_type requires use_size = true", &j));
-                    }
+                    JSON_ASSERT(use_count);
                    oa->write_character(to_char_type('$'));
                    oa->write_character(bjdata_draft3 ? 'B' : 'U');
                }
@@ -17860,10 +17818,7 @@ class binary_writer
                bool prefix_required = true;
                if (use_type && !j.m_data.m_value.object->empty())
                {
-                    if (!use_count)
-                    {
-                        JSON_THROW(other_error::create(502, "use_type requires use_size = true", &j));
-                    }
+                    JSON_ASSERT(use_count);
                    const CharType first_prefix = ubjson_prefix(j.front(), use_bjdata);
                    const bool same_prefix = std::all_of(j.begin(), j.end(),
                                                         [this, first_prefix, use_bjdata](const BasicJsonType & v)
@@ -18622,23 +18577,7 @@ class binary_writer
            {
                return true;
            }
-
-            // a dimension that does not fit into std::size_t, or a product that
-            // overflows it, would wrap around and could match the size of
-            // _ArrayData_ by accident; the resulting header announces an
-            // element count that no reader can honor (the binary reader rejects
-            // it with out_of_range.408), so encode as a plain object instead
-            const auto dim = el.template get<std::uint64_t>();
-            if (!value_in_range_of<std::size_t>(dim))
-            {
-                return true;
-            }
-            const auto dim_size = static_cast<std::size_t>(dim);
-            if (dim_size != 0 && len > (std::numeric_limits<std::size_t>::max)() / dim_size)
-            {
-                return true;
-            }
-            len *= dim_size;
+            len *= static_cast<std::size_t>(el.template get<std::uint64_t>());
        }

        key = "_ArrayData_";
@@ -24870,10 +24809,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
            if (merge_objects && it.value().is_object())
            {
                auto it2 = m_data.m_value.object->find(it.key());
-                // Only recurse when the existing value is itself an object.
-                // Otherwise overwrite, matching the documented "all other values
-                // are overwritten as usual" behavior (see #5402).
-                if (it2 != m_data.m_value.object->end() && it2->second.is_object())
+                if (it2 != m_data.m_value.object->end())
                {
                    it2->second.update(it.value(), true);
 #if JSON_DIAGNOSTICS
@@ -25009,12 +24945,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    // note parentheses around operands are necessary; see
    // https://github.com/nlohmann/json/issues/1530
-    // Mixed signed/unsigned integer comparisons check whether the signed value
-    // is negative before casting. If it is, the comparison is performed with
-    // the fixed values -1 and 1, which preserves the ordering relationship
-    // because any negative signed value is smaller than any unsigned value.
-    // Otherwise, the non-negative signed value is cast to unsigned before the
-    // comparison to avoid wraparound.
 #define JSON_IMPLEMENT_OPERATOR(op, null_result, unordered_result, default_result)                       \
    const auto lhs_type = lhs.type();                                                                    \
    const auto rhs_type = rhs.type();                                                                    \
@@ -25073,16 +25003,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    }                                                                                                    \
    else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_integer)                \
    {                                                                                                    \
-        return (rhs.m_data.m_value.number_integer < 0)                                                   \
-               ? (number_integer_t(1) op number_integer_t(-1))                                           \
-               : (lhs.m_data.m_value.number_unsigned op static_cast<number_unsigned_t>(rhs.m_data.m_value.number_integer)); \
+        return static_cast<number_integer_t>(lhs.m_data.m_value.number_unsigned) op rhs.m_data.m_value.number_integer; \
    }                                                                                                    \
    else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_unsigned)                \
    {                                                                                                    \
-        return (lhs.m_data.m_value.number_integer < 0)                                                   \
-               ? (number_integer_t(-1) op number_integer_t(1))                                           \
-               : (static_cast<number_unsigned_t>(lhs.m_data.m_value.number_integer) op rhs.m_data.m_value.number_unsigned); \
-    }                                                                                             \
+        return lhs.m_data.m_value.number_integer op static_cast<number_integer_t>(rhs.m_data.m_value.number_unsigned); \
+    }                                                                                                    \
    else if(compares_unordered(lhs, rhs))\
    {\
        return (unordered_result);\
@@ -2730,27 +2730,6 @@ TEST_CASE("BJData")
                CHECK(json::from_bjdata(json::to_bjdata(j_type), true, true) == j_type);
                CHECK(json::from_bjdata(json::to_bjdata(j_size), true, true) == j_size);
            }
-
-            SECTION("ndarray whose dimensions overflow stays as object")
-            {
-                // the product of the dimensions wraps around std::size_t to 0
-                // and so matches the size of the empty _ArrayData_; writing this
-                // as an ndarray would announce an element count no reader can
-                // honor, so it has to stay a plain object
-                json j_overflow = json({{"_ArrayData_", json::array()}, {"_ArraySize_", {9223372036854775808ull, 2}}, {"_ArrayType_", "uint8"}});
-                CHECK(json::from_bjdata(json::to_bjdata(j_overflow), true, true) == j_overflow);
-
-                // a single dimension that does not fit into std::size_t is
-                // rejected for the same reason (only observable where
-                // std::size_t is narrower than 64 bit)
-                json j_huge = json({{"_ArrayData_", json::array()}, {"_ArraySize_", {18446744073709551615ull}}, {"_ArrayType_", "uint8"}});
-                CHECK(json::from_bjdata(json::to_bjdata(j_huge), true, true) == j_huge);
-
-                // a well-formed ndarray is still encoded as one
-                json j_ok = json({{"_ArrayData_", {1, 2, 3, 4, 5, 6}}, {"_ArraySize_", {2, 3}}, {"_ArrayType_", "uint8"}});
-                CHECK(json::to_bjdata(j_ok) == std::vector<uint8_t>({'[', '$', 'U', '#', '[', 'i', 2, 'i', 3, ']', 1, 2, 3, 4, 5, 6}));
-                CHECK(json::from_bjdata(json::to_bjdata(j_ok), true, true) == j_ok);
-            }
        }
    }

@@ -3843,48 +3822,6 @@ TEST_CASE("all BJData first bytes")
 }
 #endif

-TEST_CASE("BJData use_type requires use_size")
-{
-    SECTION("non-empty object throws other_error.502")
-    {
-        const json j = {{"a", 1}, {"b", 2}};
-        CHECK_THROWS_WITH_AS(json::to_bjdata(j, false, true),
-                             "[json.exception.other_error.502] use_type requires use_size = true",
-                             json::other_error&);
-    }
-
-    SECTION("non-empty array throws other_error.502")
-    {
-        const json j = {1, 2, 3};
-        CHECK_THROWS_WITH_AS(json::to_bjdata(j, false, true),
-                             "[json.exception.other_error.502] use_type requires use_size = true",
-                             json::other_error&);
-    }
-
-    SECTION("scalars do not throw with use_type=true, use_count=false")
-    {
-        CHECK_NOTHROW(json::to_bjdata(42, false, true));
-        CHECK_NOTHROW(json::to_bjdata(3.14, false, true));
-        CHECK_NOTHROW(json::to_bjdata("hello", false, true));
-        CHECK_NOTHROW(json::to_bjdata(true, false, true));
-        CHECK_NOTHROW(json::to_bjdata(nullptr, false, true));
-    }
-
-    SECTION("empty containers do not throw with use_type=true, use_count=false")
-    {
-        CHECK_NOTHROW(json::to_bjdata(json::array(), false, true));
-        CHECK_NOTHROW(json::to_bjdata(json::object(), false, true));
-    }
-
-    SECTION("valid combinations on non-empty containers")
-    {
-        const json j = {{"a", 1}, {"b", 2}};
-        CHECK_NOTHROW(json::to_bjdata(j, false, false));
-        CHECK_NOTHROW(json::to_bjdata(j, true, false));
-        CHECK_NOTHROW(json::to_bjdata(j, true, true));
-    }
-}
-
 TEST_CASE("BJData roundtrips" * doctest::skip())
 {
    SECTION("input from self-generated BJData files")
@@ -2565,16 +2565,11 @@ TEST_CASE("Tagged values")
    const json j = "s";
    auto v = json::to_cbor(j);

-    const json j_bin_payload = json::binary(std::vector<std::uint8_t> {0x01, 0x02, 0x03});
-    auto v_bin_payload = json::to_cbor(j_bin_payload);
-
-    SECTION("0xC0..0xD7")
+    SECTION("0xC6..0xD4")
    {
        for (const auto b : std::vector<std::uint8_t>
    {
-        0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5,
-        0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4,
-        0xD5, 0xD6, 0xD7
+        0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4
    })
        {
            CAPTURE(b);
@@ -2594,12 +2589,6 @@ TEST_CASE("Tagged values")

            auto j_tagged_stored = json::from_cbor(v_tagged, true, true, json::cbor_tag_handler_t::store);
            CHECK(j_tagged_stored == j);
-
-            auto v_binary_tagged = v_bin_payload;
-            v_binary_tagged.insert(v_binary_tagged.begin(), b);
-            auto j_binary_tagged_stored = json::from_cbor(v_binary_tagged, true, true, json::cbor_tag_handler_t::store);
-            CHECK(j_binary_tagged_stored == j_bin_payload);
-            CHECK(!j_binary_tagged_stored.get_binary().has_subtype());
        }
    }

@@ -15,8 +15,6 @@

 #include "doctest_compatibility.h"

-#include <cstdint>
-
 #define JSON_TESTS_PRIVATE
 #include <nlohmann/json.hpp>
 using nlohmann::json;
@@ -257,75 +255,6 @@ TEST_CASE("lexicographical comparison operators")
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 21
        };

-        SECTION("signed/unsigned mixed comparison above INT64_MAX")
-        {
-            const json above_int64_max = static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()) + 1ULL;
-            const json max_uint64 = (std::numeric_limits<std::uint64_t>::max)();
-            const json negative_one = -1;
-            const json one = 1;
-            const json max_int64 = (std::numeric_limits<std::int64_t>::max)();
-
-            CHECK_FALSE(above_int64_max == negative_one);
-            CHECK(above_int64_max != negative_one);
-            CHECK(negative_one < above_int64_max);
-            CHECK(negative_one <= above_int64_max);
-            CHECK_FALSE(negative_one > above_int64_max);
-            CHECK_FALSE(negative_one >= above_int64_max);
-            CHECK_FALSE(above_int64_max < negative_one);
-            CHECK_FALSE(above_int64_max <= negative_one);
-            CHECK(above_int64_max > negative_one);
-            CHECK(above_int64_max >= negative_one);
-            CHECK(negative_one != above_int64_max);
-            CHECK_FALSE(negative_one == above_int64_max);
-
-            CHECK_FALSE(max_uint64 == negative_one);
-            CHECK(max_uint64 != negative_one);
-            CHECK(negative_one < max_uint64);
-            CHECK(negative_one <= max_uint64);
-            CHECK_FALSE(negative_one > max_uint64);
-            CHECK_FALSE(negative_one >= max_uint64);
-            CHECK_FALSE(max_uint64 < negative_one);
-            CHECK_FALSE(max_uint64 <= negative_one);
-            CHECK(max_uint64 > negative_one);
-            CHECK(max_uint64 >= negative_one);
-            CHECK(negative_one != max_uint64);
-            CHECK_FALSE(negative_one == max_uint64);
-
-            CHECK_FALSE(one == above_int64_max);
-            CHECK(one != above_int64_max);
-            CHECK(one < above_int64_max);
-            CHECK(one <= above_int64_max);
-            CHECK_FALSE(one > above_int64_max);
-            CHECK_FALSE(one >= above_int64_max);
-            CHECK_FALSE(above_int64_max < one);
-            CHECK_FALSE(above_int64_max <= one);
-            CHECK(above_int64_max > one);
-            CHECK(above_int64_max >= one);
-
-            CHECK_FALSE(max_int64 == above_int64_max);
-            CHECK(max_int64 != above_int64_max);
-            CHECK(max_int64 < above_int64_max);
-            CHECK(max_int64 <= above_int64_max);
-            CHECK_FALSE(max_int64 > above_int64_max);
-            CHECK_FALSE(max_int64 >= above_int64_max);
-            CHECK_FALSE(above_int64_max < max_int64);
-            CHECK_FALSE(above_int64_max <= max_int64);
-            CHECK(above_int64_max > max_int64);
-            CHECK(above_int64_max >= max_int64);
-
-#if JSON_HAS_THREE_WAY_COMPARISON
-            // JSON_HAS_CPP_20 (do not remove; see note at top of file)
-            CHECK((negative_one <=> above_int64_max) == std::partial_ordering::less); // *NOPAD*
-            CHECK((above_int64_max <=> negative_one) == std::partial_ordering::greater); // *NOPAD*
-            CHECK((negative_one <=> max_uint64) == std::partial_ordering::less); // *NOPAD*
-            CHECK((max_uint64 <=> negative_one) == std::partial_ordering::greater); // *NOPAD*
-            CHECK((one <=> above_int64_max) == std::partial_ordering::less); // *NOPAD*
-            CHECK((above_int64_max <=> one) == std::partial_ordering::greater); // *NOPAD*
-            CHECK((max_int64 <=> above_int64_max) == std::partial_ordering::less); // *NOPAD*
-            CHECK((above_int64_max <=> max_int64) == std::partial_ordering::greater); // *NOPAD*
-#endif
-        }
-
        SECTION("compares unordered")
        {
            std::vector<std::vector<bool>> expected =
@@ -38,36 +38,6 @@ TEST_CASE("Better diagnostics with positions")
                             "[json.exception.type_error.302] type must be number, but is string", json::type_error);
    }

-    SECTION("positions of strings containing escape sequences")
-    {
-        // escape sequences make the token longer than the string it parses to,
-        // so the positions must not be derived from the parsed value's length
-        const auto check = [](const std::string & text, const std::string & token)
-        {
-            CAPTURE(text)
-            CAPTURE(token)
-            const json j = json::parse(text);
-            const json& v = j.at("a");
-            CHECK(text.substr(v.start_pos(), v.end_pos() - v.start_pos()) == token);
-        };
-
-        check(R"({"a":"plain"})", R"("plain")");
-        check(R"({"a":"tab\there"})", R"("tab\there")");
-        check(R"({"a":"\n\n\n\n\n\n"})", R"("\n\n\n\n\n\n")");
-        check(R"({"a":"\""})", R"("\"")");
-        check(R"({"a":"\\"})", R"("\\")");
-        check(R"({"a":"é"})", R"("é")");
-        check(R"({"a":"🌞"})", R"("🌞")");
-        check("{\"a\":\"\xc3\xa9\"}", "\"\xc3\xa9\"");  // multi-byte UTF-8, no escapes
-
-        // a string at the root, where an escape would otherwise push the
-        // reported start position past the opening quote
-        const std::string root = R"("a\tb")";
-        const json j = json::parse(root);
-        CHECK(j.start_pos() == 0);
-        CHECK(j.end_pos() == root.size());
-    }
-
    SECTION("JSON patch add to primitive parent (#4292)")
    {
        // the JSON Patch "add" target /foo/bar/baz has a string parent
@@ -396,6 +396,72 @@ TEST_CASE("JSON pointers")
        }
    }

+    SECTION("creating intermediate levels")
+    {
+        SECTION("tokens that are valid array indices create arrays")
+        {
+            json j;
+            j["/0"_json_pointer] = 1;
+            CHECK(j == json({1}));
+
+            json j2;
+            j2["/2"_json_pointer] = 1;
+            CHECK(j2 == json({nullptr, nullptr, 1}));
+
+            json j3;
+            j3["/-"_json_pointer] = 1;
+            CHECK(j3 == json({1}));
+
+            json j4;
+            j4["/foo/0/0"_json_pointer] = 1;
+            CHECK(j4 == json({{"foo", {{1}}}}));
+        }
+
+        SECTION("tokens that are no valid array indices create objects")
+        {
+            json j;
+            j["/one"_json_pointer] = 1;
+            CHECK(j == json({{"one", 1}}));
+
+            // leading '0' can never be a valid array index (RFC 6901, Sect. 4)
+            json j2;
+            j2["/01"_json_pointer] = 1;
+            CHECK(j2 == json({{"01", 1}}));
+
+            // the empty token is a valid object key, but no valid array index
+            json j3;
+            j3["/"_json_pointer] = 1;
+            CHECK(j3 == json({{"", 1}}));
+        }
+
+        SECTION("creating a level yields the same result as reusing it (#5357)")
+        {
+            json j;
+            j["/a/b/01/d"_json_pointer] = "value";
+
+            json j_init = json::object();
+            j_init["/a/b"_json_pointer] = json::object();
+            j_init["/a/b/01/d"_json_pointer] = "value";
+
+            const json expected = json::parse(R"({"a":{"b":{"01":{"d":"value"}}}})");
+            CHECK(j == expected);
+            CHECK(j_init == expected);
+
+            // unflatten uses the same key
+            const json flat = {{"/a/b/01/d", "value"}};
+            CHECK(flat.unflatten() == expected);
+        }
+
+        SECTION("existing arrays still reject invalid indices")
+        {
+            json j = {1, 2, 3};
+            CHECK_THROWS_WITH_AS(j["/01"_json_pointer],
+                                 "[json.exception.parse_error.106] parse error: array index '01' must not begin with '0'", json::parse_error&);
+            CHECK_THROWS_WITH_AS(j.at("/01"_json_pointer),
+                                 "[json.exception.parse_error.106] parse error: array index '01' must not begin with '0'", json::parse_error&);
+        }
+    }
+
    SECTION("flatten")
    {
        json j =
@@ -801,30 +801,6 @@ TEST_CASE("modifiers")
                    j1.update(j2, true);
                    CHECK(j1 == json({{"string", "t"}, {"numbers", 1}}));
                }
-
-                SECTION("overwrite primitive with object")
-                {
-                    json j1 = {{"k", 1}};
-                    json const j2 = {{"k", {{"x", 2}}}};
-                    j1.update(j2, true);
-                    CHECK(j1 == json({{"k", {{"x", 2}}}}));
-                }
-
-                SECTION("overwrite array with object")
-                {
-                    json j1 = {{"k", {1, 2}}};
-                    json const j2 = {{"k", {{"x", 2}}}};
-                    j1.update(j2, true);
-                    CHECK(j1 == json({{"k", {{"x", 2}}}}));
-                }
-
-                SECTION("overwrite nested primitive with object")
-                {
-                    json j1 = {{"k", {{"inner", 1}}}};
-                    json const j2 = {{"k", {{"inner", {{"x", 2}}}}}};
-                    j1.update(j2, true);
-                    CHECK(j1 == json({{"k", {{"inner", {{"x", 2}}}}}}));
-                }
            }
        }
    }
@@ -1555,15 +1555,4 @@ TEST_CASE("issue #5338 - truncated CBOR tagged binary subtype is rejected")
    }
 }

-TEST_CASE("issue #5402 - update(merge_objects=true) overwrites a primitive with an object")
-{
-    json t = {{"k", 1}};
-    t.update(json{{"k", {{"x", 2}}}}, true);
-    CHECK(t == json({{"k", {{"x", 2}}}}));
-
-    json mixed = {{"keep", {{"a", 1}}}, {"replace", 1}};
-    mixed.update(json{{"keep", {{"b", 2}}}, {"replace", {{"x", 2}}}}, true);
-    CHECK(mixed == json({{"keep", {{"a", 1}, {"b", 2}}}, {"replace", {{"x", 2}}}}));
-}
-
 DOCTEST_CLANG_SUPPRESS_WARNING_POP
@@ -1713,44 +1713,6 @@ TEST_CASE("UBJSON")
            CHECK(json::to_ubjson(json::from_ubjson(s_L)) == s_i);
        }

-        SECTION("no-op markers")
-        {
-            // A no-op ('N') is valid wherever a value may start; it is consumed
-            // by get_ignore_noop() before the value is read. It is not valid
-            // where a string length type specification is expected.
-
-            SECTION("accepted where a value may start")
-            {
-                // at top level, also repeated
-                CHECK(json::from_ubjson(std::vector<uint8_t>({'N', 'i', 1})) == json(1));
-                CHECK(json::from_ubjson(std::vector<uint8_t>({'N', 'N', 'N', 'i', 1})) == json(1));
-
-                // inside an array of unknown size, before and after an element
-                CHECK(json::from_ubjson(std::vector<uint8_t>({'[', 'N', 'i', 1, ']'})) == json({1}));
-                CHECK(json::from_ubjson(std::vector<uint8_t>({'[', 'i', 1, 'N', ']'})) == json({1}));
-
-                // inside an object of unknown size: before a key, between key
-                // and value, and before the closing '}'
-                CHECK(json::from_ubjson(std::vector<uint8_t>({'{', 'N', 'U', 1, 'a', 'i', 1, '}'})) == json({{"a", 1}}));
-                CHECK(json::from_ubjson(std::vector<uint8_t>({'{', 'U', 1, 'a', 'N', 'i', 1, '}'})) == json({{"a", 1}}));
-                CHECK(json::from_ubjson(std::vector<uint8_t>({'{', 'U', 1, 'a', 'i', 1, 'N', '}'})) == json({{"a", 1}}));
-            }
-
-            SECTION("rejected where a length type specification is expected")
-            {
-                json _;
-
-                // after the 'S' marker of a string value
-                std::vector<uint8_t> const v_S = {'S', 'N', 'U', 1, 'a'};
-                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v_S), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing UBJSON string: expected length type specification (U, i, I, l, L); last byte: 0x4E", json::parse_error&);
-
-                // as the key length of an object with a known size, where
-                // no-ops are not permitted in the first place
-                std::vector<uint8_t> const v_key = {'{', '#', 'i', 1, 'N', 'U', 1, 'a', 'i', 1};
-                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v_key), "[json.exception.parse_error.113] parse error at byte 5: syntax error while parsing UBJSON string: expected length type specification (U, i, I, l, L); last byte: 0x4E", json::parse_error&);
-            }
-        }
-
        SECTION("number")
        {
            SECTION("float")
@@ -2503,48 +2465,6 @@ TEST_CASE("all UBJSON first bytes")
 }
 #endif

-TEST_CASE("UBJSON use_type requires use_size")
-{
-    SECTION("non-empty array throws other_error.502")
-    {
-        const json j = {1, 2, 3};
-        CHECK_THROWS_WITH_AS(json::to_ubjson(j, false, true),
-                             "[json.exception.other_error.502] use_type requires use_size = true",
-                             json::other_error&);
-    }
-
-    SECTION("non-empty object throws other_error.502")
-    {
-        const json j = {{"a", 1}, {"b", 2}};
-        CHECK_THROWS_WITH_AS(json::to_ubjson(j, false, true),
-                             "[json.exception.other_error.502] use_type requires use_size = true",
-                             json::other_error&);
-    }
-
-    SECTION("scalars do not throw with use_type=true, use_count=false")
-    {
-        CHECK_NOTHROW(json::to_ubjson(42, false, true));
-        CHECK_NOTHROW(json::to_ubjson(3.14, false, true));
-        CHECK_NOTHROW(json::to_ubjson("hello", false, true));
-        CHECK_NOTHROW(json::to_ubjson(true, false, true));
-        CHECK_NOTHROW(json::to_ubjson(nullptr, false, true));
-    }
-
-    SECTION("empty containers do not throw with use_type=true, use_count=false")
-    {
-        CHECK_NOTHROW(json::to_ubjson(json::array(), false, true));
-        CHECK_NOTHROW(json::to_ubjson(json::object(), false, true));
-    }
-
-    SECTION("valid combinations on non-empty containers")
-    {
-        const json j = {1, 2, 3};
-        CHECK_NOTHROW(json::to_ubjson(j, false, false));
-        CHECK_NOTHROW(json::to_ubjson(j, true, false));
-        CHECK_NOTHROW(json::to_ubjson(j, true, true));
-    }
-}
-
 TEST_CASE("UBJSON roundtrips" * doctest::skip())
 {
    SECTION("input from self-generated UBJSON files")
@@ -125,16 +125,6 @@ TEST_CASE("wide strings")
            std::u32string const w = U"\"\x110000";
            json _;
            CHECK_THROWS_AS(_ = json::parse(w), json::parse_error&);
-
-            // a code unit above U+10FFFF must not be narrowed onto the EOF
-            // sentinel: 0xFFFFFFFF would otherwise end the document silently and
-            // let everything following it pass the strict end-of-input check
-            std::u32string const trailing{U'[', U'1', U']', static_cast<char32_t>(0xFFFFFFFF), U'x'};
-            CHECK_THROWS_WITH_AS(_ = json::parse(trailing), "[json.exception.parse_error.101] parse error at line 1, column 4: syntax error while parsing value - invalid literal; last read: '1]\xFF'; expected end of input", json::parse_error&);
-            CHECK(!json::accept(trailing));
-
-            // the same unit inside a string is reported as an ill-formed byte
-            CHECK_THROWS_WITH_AS(_ = json::parse(std::u32string{U'"', static_cast<char32_t>(0xFFFFFFFF), U'"'}), "[json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '\"\xFF'", json::parse_error&);
        }
    }
 }