Detect used C++ standard library (#4793)

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

.github/CONTRIBUTING.md

@@ -1,7 +1,7 @@
 # Contribution Guidelines
 
 Thank you for your interest in contributing to this project! What began as an exercise to explore the exciting features
-of C++11 has evolved into a [widely-used](https://json.nlohmann.me/home/customers/) JSON library. I truly appreciate all
+of C++11 has evolved into a [widely used](https://json.nlohmann.me/home/customers/) JSON library. I truly appreciate all
 the contributions from the community, whether it's proposing features, identifying bugs, or fixing mistakes! To ensure
 that our collaboration is efficient and effective, please follow these guidelines.
 
@@ -21,7 +21,7 @@ Clearly describe the issue:
 
 - If it is a bug, please describe how to **reproduce** it. If possible, attach a _complete example_ which demonstrates
   the error. Please also state what you **expected** to happen instead of the error.
-- If you propose a change or addition, try to give an **example** how the improved code could look like or how to use
+- If you propose a change or addition, try to give an **example** what the improved code could look like or how to use
   it.
 - If you found a compilation error, please tell us which **compiler** (version and operating system) you used and paste
   the (relevant part of) the error messages to the ticket.
@@ -66,21 +66,21 @@ certification that he or she has the right to submit the patch for inclusion int
 
 ### Describe your changes
 
-This library is primarily maintained as a spare-time project. As such, I can not make any guarantee how quickly changes
+This library is primarily maintained as a spare-time project. As such, I cannot make any guarantee how quickly changes
 are merged and released. Therefore, it is very important to make the review as smooth as possible by explaining not only
 _what_ you changed, but _why_. This rationale can be very valuable down the road when improvements or bugs are discussed
 years later.
 
-### Reference existing issues
+### Reference an existing issue
 
 [Link a pull request to an issue](https://docs.github.com/en/issues/tracking-your-work-with-issues/using-issues/linking-a-pull-request-to-an-issue)
-to clarify that a fix is forthcoming and which issue can be closed after merging. Only few cases (e.g., fixing typos)
+to clarify that a fix is forthcoming and which issue can be closed after merging. Only a few cases (e.g., fixing typos)
-don’t require prior discussions.
+do not require prior discussions.
 
 ### Write tests
 
 The library has an extensive test suite that currently covers [100 %](https://coveralls.io/github/nlohmann/json) of the
-library's code. These test are crucial to maintain API stability and give future contributors confidence that they do
+library's code. These tests are crucial to maintain API stability and give future contributors confidence that they do
 not accidentally break things. As Titus Winters aptly put it:
 
 > If you liked it, you should have put a test on it.
@@ -118,14 +118,14 @@ exception into account.
 #### Coverage
 
 If test coverage decreases, an automatic warning comment will be posted on the pull request. You can access a code
-coverage report as artifact to the “Ubuntu” workflow.
+coverage report as an artifact to the “Ubuntu” workflow.
 
 ### Update the documentation
 
 The [main documentation](https://json.nlohmann.me) of the library is generated from the files
 [`docs/mkdocs/docs`](https://github.com/nlohmann/json/blob/develop/docs/mkdocs/docs). This folder contains dedicated
 pages for [certain features](https://github.com/nlohmann/json/tree/develop/docs/mkdocs/docs/features), a list of
-[all exceptions](https://github.com/nlohmann/json/blob/develop/docs/mkdocs/docs/home/exceptions.md), and an
+[all exceptions](https://github.com/nlohmann/json/blob/develop/docs/mkdocs/docs/home/exceptions.md), and 
 [extensive API documentation](https://github.com/nlohmann/json/tree/develop/docs/mkdocs/docs/api) with details on every
 public API function.
 
@@ -136,7 +136,7 @@ make install_venv -C docs/mkdocs
 make serve -C docs/mkdocs
 ```
 
-The documentation will then available at <http://127.0.0.1:8000/>. See the documentation of
+The documentation will then be available at <http://127.0.0.1:8000/>. See the documentation of
 [mkdocs](https://www.mkdocs.org) and [Material for MkDocs](https://squidfunk.github.io/mkdocs-material/) for more
 information.
 
@@ -184,8 +184,8 @@ API of the 3.x.y version is broken. This includes:
 Although these guidelines may seem restrictive, they are essential for maintaining the library’s utility.
 
 Breaking changes may be introduced when they are guarded with a feature macro such as
-[`JSON_USE_IMPLICIT_CONVERSIONS`](https://json.nlohmann.me/api/macros/json_use_implicit_conversions/) which allows to
+[`JSON_USE_IMPLICIT_CONVERSIONS`](https://json.nlohmann.me/api/macros/json_use_implicit_conversions/) which allows 
-selectively change the behavior of the library. In next steps, the current behavior can then be deprecated. Using
+selectively changing the behavior of the library. In next steps, the current behavior can then be deprecated. Using
 feature macros then allows users to test their code against the library in the next major release.
 
 ### Break C++11 language conformance
@@ -211,7 +211,7 @@ The following areas really need contribution and are always welcomed:
 - Extending the **continuous integration** toward more exotic compilers such as Android NDK, Intel's Compiler, or the
   bleeding-edge versions Clang.
 - Improving the efficiency of the **JSON parser**. The current parser is implemented as a naive recursive descent parser
-  with hand coded string handling. More sophisticated approaches like LALR parsers would be really appreciated. That
+  with hand-coded string handling. More sophisticated approaches like LALR parsers would be really appreciated. That
   said, parser generators like Bison or ANTLR do not play nice with single-header files -- I really would like to keep
   the parser inside the `json.hpp` header, and I am not aware of approaches similar to [`re2c`](http://re2c.org) for
   parsing.

.github/ISSUE_TEMPLATE/bug.yaml

@@ -76,7 +76,7 @@ body:
       label: Library version
       description: >
         Which version of the library did you use? If it is a released version,
-        please enter the version number (e.g., 3.11.3). Otherwise, please enter
+        please enter the version number (e.g., 3.12.0). Otherwise, please enter
         the commit hash. If you got the library from another source as the
         GitHub repository (e.g., via a package manager), please also state
         this.

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,4 +1,4 @@
-[Describe your pull request here. Please read the text below the line, and make sure you follow the checklist.]
+[Describe your pull request here. Please read the text below the line and make sure you follow the checklist.]
 
 - [ ] The changes are described in detail, both the what and why.
 - [ ] If applicable, an [existing issue](https://github.com/nlohmann/json/issues) is referenced.

.github/workflows/check_amalgamation.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 
@@ -34,7 +34,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 

.github/workflows/cifuzz.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Harden Runner
-      uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+      uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
       with:
         egress-policy: audit
 

.github/workflows/codeql-analysis.yml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
     - name: Harden Runner
-      uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+      uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
       with:
         egress-policy: audit
 
@@ -36,14 +36,14 @@ jobs:
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@fc7e4a0fa01c3cca5fd6a1fddec5c0740c977aa2 # v3.28.14
+      uses: github/codeql-action/init@ff0a06e83cb2de871e5a09832bc6a81e7276941f # v3.28.18
       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@fc7e4a0fa01c3cca5fd6a1fddec5c0740c977aa2 # v3.28.14
+      uses: github/codeql-action/autobuild@ff0a06e83cb2de871e5a09832bc6a81e7276941f # v3.28.18
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@fc7e4a0fa01c3cca5fd6a1fddec5c0740c977aa2 # v3.28.14
+      uses: github/codeql-action/analyze@ff0a06e83cb2de871e5a09832bc6a81e7276941f # v3.28.18

.github/workflows/comment_check_amalgamation.yml

@@ -19,7 +19,7 @@ jobs:
       pull-requests: write
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 

.github/workflows/dependency-review.yml

@@ -17,11 +17,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 
       - name: 'Checkout Repository'
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: 'Dependency Review'
-        uses: actions/dependency-review-action@ce3cf9537a52e8119d91fd484ab5b8a807627bf8 # v4.6.0
+        uses: actions/dependency-review-action@da24556b548a50705dd671f47852072ea4c105d9 # v4.7.1

.github/workflows/labeler.yml

@@ -17,10 +17,10 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 
-      - uses: srvaroa/labeler@e216fb40e2e6d3b17d90fb1d950f98bee92f65ce # master
+      - uses: srvaroa/labeler@e7bef2249506ba9cbbd3ca5cee256abd9f930b04 # master
         env:
           GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"

.github/workflows/publish_documentation.yml

@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 

.github/workflows/scorecards.yml

@@ -36,7 +36,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         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@fc7e4a0fa01c3cca5fd6a1fddec5c0740c977aa2 # v3.28.14
+        uses: github/codeql-action/upload-sarif@ff0a06e83cb2de871e5a09832bc6a81e7276941f # v3.28.18
         with:
           sarif_file: results.sarif

.github/workflows/stale.yml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 

.github/workflows/ubuntu.yml

@@ -23,7 +23,7 @@ jobs:
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@28983e0d3955dba2bb0a6810caae0c6cf268ec0c # v4.0.0
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
       - name: Run CMake
         run: cmake -S . -B build -DJSON_CI=On
       - name: Build
@@ -46,7 +46,7 @@ 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@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 
@@ -54,7 +54,7 @@ jobs:
         run: sudo apt-get update ; sudo apt-get install -y valgrind
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@28983e0d3955dba2bb0a6810caae0c6cf268ec0c # v4.0.0
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
       - name: Run CMake
         run: cmake -S . -B build -DJSON_CI=On
       - name: Build
@@ -71,7 +71,7 @@ jobs:
         run: apt-get update ; apt-get install -y git clang-tools iwyu unzip
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@28983e0d3955dba2bb0a6810caae0c6cf268ec0c # v4.0.0
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
       - name: Run CMake
         run: cmake -S . -B build -DJSON_CI=On
       - name: Build
@@ -88,7 +88,7 @@ jobs:
         run: apt-get update ; apt-get install -y build-essential unzip wget git libssl-dev
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@28983e0d3955dba2bb0a6810caae0c6cf268ec0c # v4.0.0
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
       - name: Run CMake
         run: cmake -S . -B build -DJSON_CI=On
       - name: Build
@@ -98,7 +98,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 
@@ -143,12 +143,12 @@ jobs:
     strategy:
       matrix:
         # older GCC docker images (4, 5, 6) fail to check out code
-        compiler: ['7', '8', '9', '10', '11', '12', '13', '14', 'latest']
+        compiler: ['7', '8', '9', '10', '11', '12', '13', '14', '15', 'latest']
     container: gcc:${{ matrix.compiler }}
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@28983e0d3955dba2bb0a6810caae0c6cf268ec0c # v4.0.0
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
       - name: Run CMake
         run: cmake -S . -B build -DJSON_CI=On
       - name: Build
@@ -165,7 +165,7 @@ jobs:
         run: apt-get update ; apt-get install -y unzip git
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@28983e0d3955dba2bb0a6810caae0c6cf268ec0c # v4.0.0
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
       - name: Set env FORCE_STDCPPFS_FLAG for clang 7 / 8 / 9 / 10
         run: echo "JSON_FORCED_GLOBAL_COMPILE_OPTIONS=-DJSON_HAS_FILESYSTEM=0;-DJSON_HAS_EXPERIMENTAL_FILESYSTEM=0" >> "$GITHUB_ENV"
         if: ${{ matrix.compiler == '7' || matrix.compiler == '8' || matrix.compiler == '9' || matrix.compiler == '10' }}
@@ -183,7 +183,7 @@ jobs:
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@28983e0d3955dba2bb0a6810caae0c6cf268ec0c # v4.0.0
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
       - name: Run CMake
         run: cmake -S . -B build -DJSON_CI=On
       - name: Build
@@ -201,7 +201,7 @@ jobs:
         run: apt-get update ; apt-get install -y git unzip
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@28983e0d3955dba2bb0a6810caae0c6cf268ec0c # v4.0.0
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
       - name: Run CMake
         run: cmake -S . -B build -DJSON_CI=On
       - name: Build with libc++
@@ -221,6 +221,21 @@ jobs:
       - name: Build
         run: cmake --build build --target ci_cuda_example
 
+  ci_module_cpp20:
+    strategy:
+      matrix:
+        container: ['gcc:latest', 'silkeh/clang:latest']
+    runs-on: ubuntu-latest
+    container: ${{ matrix.container }}
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - name: Get latest CMake and ninja
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
+      - name: Run CMake
+        run: cmake -S . -B build -DJSON_CI=On
+      - name: Build
+        run: cmake --build build --target ci_module_cpp20
+
   ci_icpc:
     runs-on: ubuntu-latest
     container: ghcr.io/nlohmann/json-ci:v2.2.0
@@ -233,6 +248,24 @@ jobs:
           . /opt/intel/oneapi/setvars.sh
           cmake --build build --target ci_icpc
 
+  ci_emscripten:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
+        with:
+          egress-policy: audit
+
+      - name: Install emscripten
+        uses: mymindstorm/setup-emsdk@v14
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - name: Get latest CMake and ninja
+        uses: lukka/get-cmake@ea004816823209b8d1211e47b216185caee12cc5 # v4.02
+      - name: Run CMake
+        run: cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=$EMSDK/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake -GNinja
+      - name: Build
+        run: cmake --build build
+
   ci_test_documentation:
     runs-on: ubuntu-latest
     strategy:
@@ -240,7 +273,7 @@ jobs:
         target: [ci_test_examples, ci_test_build_documentation]
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 

.github/workflows/windows.yml

@@ -37,69 +37,48 @@ jobs:
       - name: Test
         run: cd build ; ctest -j 10 -C Debug --output-on-failure
 
-  msvc2019:
+  msvc:
-    runs-on: windows-2019
     strategy:
       matrix:
+        runs_on: [windows-2019, windows-2022]
         build_type: [Debug, Release]
         architecture: [Win32, x64]
+        std_version: [default, latest]
+
+    runs-on: ${{ matrix.runs_on }}
 
     steps:
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
-    - name: Run CMake
+      - name: Set generator
-      run: cmake -S . -B build -G "Visual Studio 16 2019" -A ${{ matrix.architecture }} -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="/W4 /WX"
+        id: generator
-      if: matrix.build_type == 'Release'
+        run: |
-    - name: Run CMake
+          if [ "${{ matrix.runs_on }}" = "windows-2019" ]; then
-      run: cmake -S . -B build -G "Visual Studio 16 2019" -A ${{ matrix.architecture }} -DJSON_BuildTests=On -DJSON_FastTests=ON -DCMAKE_CXX_FLAGS="/W4 /WX"
+            echo "generator=Visual Studio 16 2019" >> $GITHUB_ENV
-      if: matrix.build_type == 'Debug'
+          else
-    - name: Build
+            echo "generator=Visual Studio 17 2022" >> $GITHUB_ENV
-      run: cmake --build build --config ${{ matrix.build_type }} --parallel 10
+          fi
-    - name: Test
+        shell: bash
-      run: cd build ; ctest -j 10 -C ${{ matrix.build_type }} --output-on-failure
+      - name: Set extra CXX_FLAGS for latest std_version
-
+        id: cxxflags
-  msvc2019_latest:
+        run: |
-    runs-on: windows-2019
+          if [ "${{ matrix.std_version }}" = "latest" ]; then
-
+            echo "flags=/permissive- /std:c++latest /utf-8 /W4 /WX" >> $GITHUB_ENV
-    steps:
+          else
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+            echo "flags=/W4 /WX" >> $GITHUB_ENV
-    - name: Run CMake
+          fi
-      run: cmake -S . -B build -G "Visual Studio 16 2019" -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="/permissive- /std:c++latest /utf-8 /W4 /WX"
+        shell: bash
-    - name: Build
+      - name: Run CMake (Release)
-      run: cmake --build build --config Release --parallel 10
+        run: cmake -S . -B build -G "$env:generator" -A ${{ matrix.architecture }} -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="$env:flags"
-    - name: Test
+        if: matrix.build_type == 'Release'
-      run: cd build ; ctest -j 10 -C Release --output-on-failure
+        shell: pwsh
-
+      - name: Run CMake (Debug)
-  msvc2022:
+        run: cmake -S . -B build -G "$env:generator" -A ${{ matrix.architecture }} -DJSON_BuildTests=On -DJSON_FastTests=ON -DCMAKE_CXX_FLAGS="$env:flags"
-    runs-on: windows-2022
+        if: matrix.build_type == 'Debug'
-    strategy:
+        shell: pwsh
-      matrix:
+      - name: Build
-        build_type: [Debug, Release]
+        run: cmake --build build --config ${{ matrix.build_type }} --parallel 10
-        architecture: [Win32, x64]
+      - name: Test
-
+        run: cd build ; ctest -j 10 -C ${{ matrix.build_type }} --output-on-failure
-    steps:
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
-    - name: Run CMake
-      run: cmake -S . -B build -G "Visual Studio 17 2022" -A ${{ matrix.architecture }} -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="/W4 /WX"
-      if: matrix.build_type == 'Release'
-    - name: Run CMake
-      run: cmake -S . -B build -G "Visual Studio 17 2022" -A ${{ matrix.architecture }} -DJSON_BuildTests=On -DJSON_FastTests=ON -DCMAKE_CXX_FLAGS="/W4 /WX"
-      if: matrix.build_type == 'Debug'
-    - name: Build
-      run: cmake --build build --config ${{ matrix.build_type }} --parallel 10
-    - name: Test
-      run: cd build ; ctest -j 10 -C ${{ matrix.build_type }} --output-on-failure
-
-  msvc2022_latest:
-    runs-on: windows-2022
-
-    steps:
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
-    - name: Run CMake
-      run: cmake -S . -B build -G "Visual Studio 17 2022" -DJSON_BuildTests=On -DCMAKE_CXX_FLAGS="/permissive- /std:c++latest /utf-8 /W4 /WX"
-    - name: Build
-      run: cmake --build build --config Release --parallel 10
-    - name: Test
-      run: cd build ; ctest -j 10 -C Release --output-on-failure
 
   clang:
     runs-on: windows-2019
@@ -118,7 +97,7 @@ jobs:
       - name: Test
         run: cd build ; ctest -j 10 -C Debug --exclude-regex "test-unicode" --output-on-failure
 
-  clang-cl-11:
+  clang-cl-12:
     runs-on: windows-2019
     strategy:
       matrix:

.reuse/templates/json.jinja2

@@ -1,6 +1,6 @@
     __ _____ _____ _____
  __|  |   __|     |   | |  JSON for Modern C++
-|  |  |__   |  |  | | | |  version 3.11.3
+|  |  |__   |  |  | | | |  version 3.12.0
 |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 
 {% for copyright_line in copyright_lines %}

.reuse/templates/json_support.jinja2

@@ -1,6 +1,6 @@
     __ _____ _____ _____
  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
-|  |  |__   |  |  | | | |  version 3.11.3
+|  |  |__   |  |  | | | |  version 3.12.0
 |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 
 {% for copyright_line in copyright_lines %}

CITATION.cff

@@ -7,8 +7,8 @@ authors:
     email: mail@nlohmann.me
     website: https://nlohmann.me
 title: "JSON for Modern C++"
-version: 3.11.3
+version: 3.12.0
-date-released: 2023-11-28
+date-released: 2025-04-07
 license: MIT
 repository-code: "https://github.com/nlohmann"
 url: https://json.nlohmann.me

CMakeLists.txt

@@ -4,7 +4,7 @@ cmake_minimum_required(VERSION 3.5...4.0)
 ## PROJECT
 ## name and version
 ##
-project(nlohmann_json VERSION 3.11.3 LANGUAGES CXX)
+project(nlohmann_json VERSION 3.12.0 LANGUAGES CXX)
 
 ##
 ## MAIN_PROJECT CHECK

FILES.md

@@ -92,7 +92,7 @@ Further documentation:
 
 ### `.github/dependabot.yml`
 
-The configuration of [dependabot](https://github.com/dependabot) which ensures the dependencies (GitHub actions and Python packages used in the CI) remain up-to-date.
+The configuration of [dependabot](https://github.com/dependabot) which ensures the dependencies (GitHub actions and Python packages used in the CI) remain up to date.
 
 Further documentation:
 
@@ -185,7 +185,7 @@ Further documentation:
 
 ### `.reuse/dep5`
 
-The file defines the licenses of certain third-party component in the repository. The root `Makefile` contains a target `reuse` that checks for compliance.
+The file defines the licenses of certain third-party components in the repository. The root `Makefile` contains a target `reuse` that checks for compliance.
 
 Further documentation:
 
@@ -212,7 +212,7 @@ Further information:
 
 ### `LICENSES`
 
-A folder that contains every license of all licenses files (library and third-party code).
+A folder that contains every license of all license files (library and third-party code).
 
 Further documentation:
 

README.md

@@ -30,7 +30,7 @@
 - [Examples](#examples)
   - [Read JSON from a file](#read-json-from-a-file)
   - [Creating `json` objects from JSON literals](#creating-json-objects-from-json-literals)
-  - [JSON as first-class data type](#json-as-first-class-data-type)
+  - [JSON as a first-class data type](#json-as-a-first-class-data-type)
   - [Serialization / Deserialization](#serialization--deserialization)
   - [STL-like access](#stl-like-access)
   - [Conversion from STL containers](#conversion-from-stl-containers)
@@ -57,7 +57,7 @@
 
 There are myriads of [JSON](https://json.org) libraries out there, and each may even have its reason to exist. Our class had these design goals:
 
-- **Intuitive syntax**. In languages such as Python, JSON feels like a first class data type. We used all the operator magic of modern C++ to achieve the same feeling in your code. Check out the [examples below](#examples) and you'll know what I mean.
+- **Intuitive syntax**. In languages such as Python, JSON feels like a first-class data type. We used all the operator magic of modern C++ to achieve the same feeling in your code. Check out the [examples below](#examples) and you'll know what I mean.
 
 - **Trivial integration**. Our whole code consists of a single header file [`json.hpp`](https://github.com/nlohmann/json/blob/develop/single_include/nlohmann/json.hpp). That's it. No library, no subproject, no dependencies, no complex build system. The class is written in vanilla C++11. All in all, everything should require no adjustment of your compiler flags or project settings. The library is also included in all popular [package managers](https://json.nlohmann.me/integration/package_managers/).
 
@@ -107,7 +107,7 @@ Thanks everyone!
 
 :bug: If you found a **bug**, please check the [**FAQ**](https://json.nlohmann.me/home/faq/) if it is a known issue or the result of a design decision. Please also have a look at the [**issue list**](https://github.com/nlohmann/json/issues) before you [**create a new issue**](https://github.com/nlohmann/json/issues/new/choose). Please provide as much information as possible to help us understand and reproduce your issue.
 
-There is also a [**docset**](https://github.com/Kapeli/Dash-User-Contributions/tree/master/docsets/JSON_for_Modern_C%2B%2B) for the documentation browsers [Dash](https://kapeli.com/dash), [Velocity](https://velocity.silverlakesoftware.com), and [Zeal](https://zealdocs.org) that contains the full [documentation](https://json.nlohmann.me) as offline resource.
+There is also a [**docset**](https://github.com/Kapeli/Dash-User-Contributions/tree/master/docsets/JSON_for_Modern_C%2B%2B) for the documentation browsers [Dash](https://kapeli.com/dash), [Velocity](https://velocity.silverlakesoftware.com), and [Zeal](https://zealdocs.org) that contains the full [documentation](https://json.nlohmann.me) as an offline resource.
 
 ## Quick reference
 
@@ -136,7 +136,7 @@ There is also a [**docset**](https://github.com/Kapeli/Dash-User-Contributions/t
 
 Here are some examples to give you an idea how to use the class.
 
-Beside the examples below, you may want to:
+Besides the examples below, you may want to:
 
 → Check the [documentation](https://json.nlohmann.me/)\
 → Browse the [standalone example files](https://github.com/nlohmann/json/tree/develop/docs/mkdocs/docs/examples)\
@@ -195,7 +195,7 @@ json ex3 = {
 };
 ```
 
-### JSON as first-class data type
+### JSON as a first-class data type
 
 Here are some examples to give you an idea how to use the class.
 
@@ -224,13 +224,13 @@ With this library, you could write:
 // create an empty structure (null)
 json j;
 
-// add a number that is stored as double (note the implicit conversion of j to an object)
+// add a number stored as double (note the implicit conversion of j to an object)
 j["pi"] = 3.141;
 
-// add a Boolean that is stored as bool
+// add a Boolean stored as bool
 j["happy"] = true;
 
-// add a string that is stored as std::string
+// add a string stored as std::string
 j["name"] = "Niels";
 
 // add another null object by passing nullptr
@@ -239,7 +239,7 @@ j["nothing"] = nullptr;
 // add an object inside the object
 j["answer"]["everything"] = 42;
 
-// add an array that is stored as std::vector (using an initializer list)
+// add an array stored as std::vector (using an initializer list)
 j["list"] = { 1, 0, 2 };
 
 // add another object (using an initializer list of pairs)
@@ -349,7 +349,7 @@ std::cout << j_string << " == " << serialized_string << std::endl;
 
 Note the library only supports UTF-8. When you store strings with different encodings in the library, calling [`dump()`](https://json.nlohmann.me/api/basic_json/dump/) may throw an exception unless `json::error_handler_t::replace` or `json::error_handler_t::ignore` are used as error handlers.
 
-#### To/from streams (e.g. files, string streams)
+#### To/from streams (e.g., files, string streams)
 
 You can also use streams to serialize and deserialize:
 
@@ -382,7 +382,7 @@ Please note that setting the exception bit for `failbit` is inappropriate for th
 
 #### Read from iterator range
 
-You can also parse JSON from an iterator range; that is, from any container accessible by iterators whose `value_type` is an integral type of 1, 2 or 4 bytes, which will be interpreted as UTF-8, UTF-16 and UTF-32 respectively. For instance, a `std::vector<std::uint8_t>`, or a `std::list<std::uint16_t>`:
+You can also parse JSON from an iterator range; that is, from any container accessible by iterators whose `value_type` is an integral type of 1, 2, or 4 bytes, which will be interpreted as UTF-8, UTF-16, and UTF-32 respectively. For instance, a `std::vector<std::uint8_t>`, or a `std::list<std::uint16_t>`:
 
 ```cpp
 std::vector<std::uint8_t> v = {'t', 'r', 'u', 'e'};
@@ -486,7 +486,7 @@ To implement your own SAX handler, proceed as follows:
 2. Create an object of your SAX interface class, e.g. `my_sax`.
 3. Call `bool json::sax_parse(input, &my_sax)`; where the first parameter can be any input like a string or an input stream and the second parameter is a pointer to your SAX interface.
 
-Note the `sax_parse` function only returns a `bool` indicating the result of the last executed SAX event. It does not return a  `json` value - it is up to you to decide what to do with the SAX events. Furthermore, no exceptions are thrown in case of a parse error - it is up to you what to do with the exception object passed to your `parse_error` implementation. Internally, the SAX interface is used for the DOM parser (class `json_sax_dom_parser`) as well as the acceptor (`json_sax_acceptor`), see file [`json_sax.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/json_sax.hpp).
+Note the `sax_parse` function only returns a `bool` indicating the result of the last executed SAX event. It does not return a  `json` value - it is up to you to decide what to do with the SAX events. Furthermore, no exceptions are thrown in case of a parse error -- it is up to you what to do with the exception object passed to your `parse_error` implementation. Internally, the SAX interface is used for the DOM parser (class `json_sax_dom_parser`) as well as the acceptor (`json_sax_acceptor`), see file [`json_sax.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/json_sax.hpp).
 
 ### STL-like access
 
@@ -618,7 +618,7 @@ json j_umset(c_umset); // both entries for "one" are used
 // maybe ["one", "two", "one", "four"]
 ```
 
-Likewise, any associative key-value containers (`std::map`, `std::multimap`, `std::unordered_map`, `std::unordered_multimap`) whose keys can construct an `std::string` and whose values can be used to construct JSON values (see examples above) can be used to create a JSON object. Note that in case of multimaps only one key is used in the JSON object and the value depends on the internal order of the STL container.
+Likewise, any associative key-value containers (`std::map`, `std::multimap`, `std::unordered_map`, `std::unordered_multimap`) whose keys can construct an `std::string` and whose values can be used to construct JSON values (see examples above) can be used to create a JSON object. Note that in case of multimaps, only one key is used in the JSON object and the value depends on the internal order of the STL container.
 
 ```cpp
 std::map<std::string, int> c_map { {"one", 1}, {"two", 2}, {"three", 3} };
@@ -640,7 +640,7 @@ json j_ummap(c_ummap); // only one entry for key "three" is used
 
 ### JSON Pointer and JSON Patch
 
-The library supports **JSON Pointer** ([RFC 6901](https://tools.ietf.org/html/rfc6901)) as alternative means to address structured values. On top of this, **JSON Patch** ([RFC 6902](https://tools.ietf.org/html/rfc6902)) allows describing differences between two JSON values - effectively allowing patch and diff operations known from Unix.
+The library supports **JSON Pointer** ([RFC 6901](https://tools.ietf.org/html/rfc6901)) as an alternative means to address structured values. On top of this, **JSON Patch** ([RFC 6902](https://tools.ietf.org/html/rfc6902)) allows describing differences between two JSON values -- effectively allowing patch and diff operations known from Unix.
 
 ```cpp
 // a JSON value
@@ -873,7 +873,7 @@ namespace ns {
 
 This requires a bit more advanced technique. But first, let's see how this conversion mechanism works:
 
-The library uses **JSON Serializers** to convert types to json.
+The library uses **JSON Serializers** to convert types to JSON.
 The default serializer for `nlohmann::json` is `nlohmann::adl_serializer` (ADL means [Argument-Dependent Lookup](https://en.cppreference.com/w/cpp/language/adl)).
 
 It is implemented like this (simplified):
@@ -923,7 +923,7 @@ namespace nlohmann {
 
 #### How can I use `get()` for non-default constructible/non-copyable types?
 
-There is a way, if your type is [MoveConstructible](https://en.cppreference.com/w/cpp/named_req/MoveConstructible). You will need to specialize the `adl_serializer` as well, but with a special `from_json` overload:
+There is a way if your type is [MoveConstructible](https://en.cppreference.com/w/cpp/named_req/MoveConstructible). You will need to specialize the `adl_serializer` as well, but with a special `from_json` overload:
 
 ```cpp
 struct move_only_type {
@@ -1012,7 +1012,7 @@ struct bad_serializer
 
 ### Specializing enum conversion
 
-By default, enum values are serialized to JSON as integers. In some cases this could result in undesired behavior. If an enum is modified or re-ordered after data has been serialized to JSON, the later de-serialized JSON data may be undefined or a different enum value than was originally intended.
+By default, enum values are serialized to JSON as integers. In some cases, this could result in undesired behavior. If an enum is modified or re-ordered after data has been serialized to JSON, the later deserialized JSON data may be undefined or a different enum value than was originally intended.
 
 It is possible to more precisely specify how a given enum is mapped to and from JSON as shown below:
 
@@ -1168,7 +1168,7 @@ Please note:
 
     The code compiles successfully with [Android NDK](https://developer.android.com/ndk/index.html?hl=ml), Revision 9 - 11 (and possibly later) and [CrystaX's Android NDK](https://www.crystax.net/en/android/ndk) version 10.
 
-- For GCC running on MinGW or Android SDK, the error `'to_string' is not a member of 'std'` (or similarly, for `strtod` or `strtof`) may occur. Note this is not an issue with the code,  but rather with the compiler itself. On Android, see above to build with a newer environment.  For MinGW, please refer to [this site](https://tehsausage.com/mingw-to-string) and [this discussion](https://github.com/nlohmann/json/issues/136) for information on how to fix this bug. For Android NDK using `APP_STL := gnustl_static`, please refer to [this discussion](https://github.com/nlohmann/json/issues/219).
+- For GCC running on MinGW or Android SDK, the error `'to_string' is not a member of 'std'` (or similarly, for `strtod` or `strtof`) may occur. Note this is not an issue with the code, but rather with the compiler itself. On Android, see above to build with a newer environment.  For MinGW, please refer to [this site](https://tehsausage.com/mingw-to-string) and [this discussion](https://github.com/nlohmann/json/issues/136) for information on how to fix this bug. For Android NDK using `APP_STL := gnustl_static`, please refer to [this discussion](https://github.com/nlohmann/json/issues/219).
 
 - Unsupported versions of GCC and Clang are rejected by `#error` directives. This can be switched off by defining `JSON_SKIP_UNSUPPORTED_COMPILER_CHECK`. Note that you can expect no support in this case.
 
@@ -1187,7 +1187,7 @@ using json = nlohmann::json;
 
 to the files you want to process JSON and set the necessary switches to enable C++11 (e.g., `-std=c++11` for GCC and Clang).
 
-You can further use file [`include/nlohmann/json_fwd.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/json_fwd.hpp) for forward-declarations. The installation of json_fwd.hpp (as part of cmake's install step), can be achieved by setting `-DJSON_MultipleHeaders=ON`.
+You can further use file [`include/nlohmann/json_fwd.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/json_fwd.hpp) for forward-declarations. The installation of `json_fwd.hpp` (as part of cmake's install step) can be achieved by setting `-DJSON_MultipleHeaders=ON`.
 
 ### CMake
 
@@ -1199,7 +1199,7 @@ To use this library from a CMake project, you can locate it directly with `find_
 
 ```cmake
 # CMakeLists.txt
-find_package(nlohmann_json 3.11.3 REQUIRED)
+find_package(nlohmann_json 3.12.0 REQUIRED)
 ...
 add_library(foo ...)
 ...
@@ -1243,13 +1243,13 @@ Example:
 ```cmake
 include(FetchContent)
 
-FetchContent_Declare(json URL https://github.com/nlohmann/json/releases/download/v3.11.3/json.tar.xz)
+FetchContent_Declare(json URL https://github.com/nlohmann/json/releases/download/v3.12.0/json.tar.xz)
 FetchContent_MakeAvailable(json)
 
 target_link_libraries(foo PRIVATE nlohmann_json::nlohmann_json)
 ```
 
-**Note**: It is recommended to use the URL approach described above which is supported as of version 3.10.0. See
+**Note**: It is recommended to use the URL approach described above, which is supported as of version 3.10.0. See
 <https://json.nlohmann.me/integration/cmake/#fetchcontent> for more information.
 
 #### Supporting Both
@@ -1275,7 +1275,7 @@ target_link_libraries(foo PRIVATE nlohmann_json::nlohmann_json)
 # thirdparty/CMakeLists.txt
 ...
 if(FOO_USE_EXTERNAL_JSON)
-  find_package(nlohmann_json 3.11.3 REQUIRED)
+  find_package(nlohmann_json 3.12.0 REQUIRED)
 else()
   set(JSON_BuildTests OFF CACHE INTERNAL "")
   add_subdirectory(nlohmann_json)
@@ -1371,13 +1371,13 @@ I deeply appreciate the help of the following people.
 9. [Florian Weber](https://github.com/Florianjw) fixed a bug in and improved the performance of the comparison operators.
 10. [Eric Cornelius](https://github.com/EricMCornelius) pointed out a bug in the handling with NaN and infinity values. He also improved the performance of the string escaping.
 11. [易思龙](https://github.com/likebeta) implemented a conversion from anonymous enums.
-12. [kepkin](https://github.com/kepkin) patiently pushed forward the support for Microsoft Visual studio.
+12. [kepkin](https://github.com/kepkin) patiently pushed forward the support for Microsoft Visual Studio.
 13. [gregmarr](https://github.com/gregmarr) simplified the implementation of reverse iterators and helped with numerous hints and improvements. In particular, he pushed forward the implementation of user-defined types.
 14. [Caio Luppi](https://github.com/caiovlp) fixed a bug in the Unicode handling.
 15. [dariomt](https://github.com/dariomt) fixed some typos in the examples.
 16. [Daniel Frey](https://github.com/d-frey) cleaned up some pointers and implemented exception-safe memory allocation.
 17. [Colin Hirsch](https://github.com/ColinH) took care of a small namespace issue.
-18. [Huu Nguyen](https://github.com/whoshuu) correct a variable name in the documentation.
+18. [Huu Nguyen](https://github.com/whoshuu) corrected a variable name in the documentation.
 19. [Silverweed](https://github.com/silverweed) overloaded `parse()` to accept an rvalue reference.
 20. [dariomt](https://github.com/dariomt) fixed a subtlety in MSVC type support and implemented the `get_ref()` function to get a reference to stored values.
 21. [ZahlGraf](https://github.com/ZahlGraf) added a workaround that allows compilation using Android NDK.
@@ -1412,7 +1412,7 @@ I deeply appreciate the help of the following people.
 50. [Jared Grubb](https://github.com/jaredgrubb) silenced a nasty documentation warning.
 51. [Yixin Zhang](https://github.com/qwename) fixed an integer overflow check.
 52. [Bosswestfalen](https://github.com/Bosswestfalen) merged two iterator classes into a smaller one.
-53. [Daniel599](https://github.com/Daniel599) helped to get Travis execute the tests with Clang's sanitizers.
+53. [Daniel599](https://github.com/Daniel599) helped to get Travis to execute the tests with Clang's sanitizers.
 54. [Jonathan Lee](https://github.com/vjon) fixed an example in the README file.
 55. [gnzlbg](https://github.com/gnzlbg) supported the implementation of user-defined types.
 56. [Alexej Harm](https://github.com/qis) helped to get the user-defined types working with Visual Studio.
@@ -1433,7 +1433,7 @@ I deeply appreciate the help of the following people.
 71. [Vincent Thiery](https://github.com/vthiery) maintains a package for the Conan package manager.
 72. [Steffen](https://github.com/koemeet) fixed a potential issue with MSVC and `std::min`.
 73. [Mike Tzou](https://github.com/Chocobo1) fixed some typos.
-74. [amrcode](https://github.com/amrcode) noted a misleading documentation about comparison of floats.
+74. [amrcode](https://github.com/amrcode) noted misleading documentation about comparison of floats.
 75. [Oleg Endo](https://github.com/olegendo) reduced the memory consumption by replacing `<iostream>` with `<iosfwd>`.
 76. [dan-42](https://github.com/dan-42) cleaned up the CMake files to simplify including/reusing of the library.
 77. [Nikita Ofitserov](https://github.com/himikof) allowed for moving values from initializer lists.
@@ -1460,13 +1460,13 @@ I deeply appreciate the help of the following people.
 98. [Vadim Evard](https://github.com/Pipeliner) fixed a Markdown issue in the README.
 99. [zerodefect](https://github.com/zerodefect) fixed a compiler warning.
 100. [Kert](https://github.com/kaidokert) allowed to template the string type in the serialization and added the possibility to override the exceptional behavior.
-101. [mark-99](https://github.com/mark-99) helped fixing an ICC error.
+101. [mark-99](https://github.com/mark-99) helped fix an ICC error.
 102. [Patrik Huber](https://github.com/patrikhuber) fixed links in the README file.
 103. [johnfb](https://github.com/johnfb) found a bug in the implementation of CBOR's indefinite length strings.
 104. [Paul Fultz II](https://github.com/pfultz2) added a note on the cget package manager.
 105. [Wilson Lin](https://github.com/wla80) made the integration section of the README more concise.
 106. [RalfBielig](https://github.com/ralfbielig) detected and fixed a memory leak in the parser callback.
-107. [agrianius](https://github.com/agrianius) allowed to dump JSON to an alternative string type.
+107. [agrianius](https://github.com/agrianius) allowed dumping JSON to an alternative string type.
 108. [Kevin Tonon](https://github.com/ktonon) overworked the C++11 compiler checks in CMake.
 109. [Axel Huebl](https://github.com/ax3l) simplified a CMake check and added support for the [Spack package manager](https://spack.io).
 110. [Carlos O'Ryan](https://github.com/coryan) fixed a typo.
@@ -1515,12 +1515,12 @@ I deeply appreciate the help of the following people.
 153. [Ivor Wanders](https://github.com/iwanders) helped to reduce the CMake requirement to version 3.1.
 154. [njlr](https://github.com/njlr) updated the Buckaroo instructions.
 155. [Lion](https://github.com/lieff) fixed a compilation issue with GCC 7 on CentOS.
-156. [Isaac Nickaein](https://github.com/nickaein) improved the integer serialization performance and  implemented the `contains()` function.
+156. [Isaac Nickaein](https://github.com/nickaein) improved the integer serialization performance and implemented the `contains()` function.
 157. [past-due](https://github.com/past-due) suppressed an unfixable warning.
 158. [Elvis Oric](https://github.com/elvisoric) improved Meson support.
 159. [Matěj Plch](https://github.com/Afforix) fixed an example in the README.
 160. [Mark Beckwith](https://github.com/wythe) fixed a typo.
-161. [scinart](https://github.com/scinart) fixed bug in the serializer.
+161. [scinart](https://github.com/scinart) fixed a bug in the serializer.
 162. [Patrick Boettcher](https://github.com/pboettch) implemented `push_back()` and `pop_back()` for JSON Pointers.
 163. [Bruno Oliveira](https://github.com/nicoddemus) added support for Conda.
 164. [Michele Caini](https://github.com/skypjack) fixed links in the README.
@@ -1562,7 +1562,7 @@ I deeply appreciate the help of the following people.
 200. [Alexander “weej” Jones](https://github.com/alex-weej) fixed an example in the README.
 201. [Antoine Cœur](https://github.com/Coeur) fixed some typos in the documentation.
 202. [jothepro](https://github.com/jothepro) updated links to the Hunter package.
-203. [Dave Lee](https://github.com/kastiglione) fixed link in the README.
+203. [Dave Lee](https://github.com/kastiglione) fixed a link in the README.
 204. [Joël Lamotte](https://github.com/Klaim) added instruction for using Build2's package manager.
 205. [Paul Jurczak](https://github.com/pauljurczak) fixed an example in the README.
 206. [Sonu Lohani](https://github.com/sonulohani) fixed a warning.
@@ -1605,7 +1605,7 @@ I deeply appreciate the help of the following people.
 243. [raduteo](https://github.com/raduteo) fixed a warning.
 244. [David Pfahler](https://github.com/theShmoo) added the possibility to compile the library without I/O support.
 245. [Morten Fyhn Amundsen](https://github.com/mortenfyhn) fixed a typo.
-246. [jpl-mac](https://github.com/jpl-mac) allowed to treat the library as a system header in CMake.
+246. [jpl-mac](https://github.com/jpl-mac) allowed treating the library as a system header in CMake.
 247. [Jason Dsouza](https://github.com/jasmcaus) fixed the indentation of the CMake file.
 248. [offa](https://github.com/offa) added a link to Conan Center to the documentation.
 249. [TotalCaesar659](https://github.com/TotalCaesar659) updated the links in the documentation to use HTTPS.
@@ -1647,7 +1647,7 @@ I deeply appreciate the help of the following people.
 285. [Wolf Vollprecht](https://github.com/wolfv) added the `patch_inplace` function.
 286. [Jake Zimmerman](https://github.com/jez) highlighted common usage patterns in the README file.
 287. [NN](https://github.com/NN---) added the Visual Studio output directory to `.gitignore`.
-288. [Romain Reignier](https://github.com/romainreignier) improved the performance the vector output adapter.
+288. [Romain Reignier](https://github.com/romainreignier) improved the performance of the vector output adapter.
 289. [Mike](https://github.com/Mike-Leo-Smith) fixed the `std::iterator_traits`.
 290. [Richard Hozák](https://github.com/zxey) added macro `JSON_NO_ENUM` to disable default enum conversions.
 291. [vakokako](https://github.com/vakokako) fixed tests when compiling with C++20.
@@ -1694,9 +1694,9 @@ I deeply appreciate the help of the following people.
 332. [taro](https://github.com/tarolling) fixed a typo in the `CODEOWNERS` file.
 333. [Ikko Eltociear Ashimine](https://github.com/eltociear) fixed a typo.
 334. [Felix Yan](https://github.com/felixonmars) fixed a typo in the README.
-335. [HO-COOH](https://github.com/HO-COOH) fixed a parentheses in the documentation.
+335. [HO-COOH](https://github.com/HO-COOH) fixed a parenthesis in the documentation.
 336. [Ivor Wanders](https://github.com/iwanders) fixed the examples to catch exception by `const&`.
-337. [miny1233](https://github.com/miny1233) fixed a parentheses in the documentation.
+337. [miny1233](https://github.com/miny1233) fixed a parenthesis in the documentation.
 338. [tomalakgeretkal](https://github.com/tomalakgeretkal) fixed a compilation error.
 339. [alferov](https://github.com/ALF-ONE) fixed a compilation error.
 340. [Craig Scott](https://github.com/craigscott-crascit) fixed a deprecation warning in CMake.
@@ -1779,7 +1779,7 @@ The library itself consists of a single header file licensed under the MIT licen
 
 The library supports **Unicode input** as follows:
 
-- Only **UTF-8** encoded input is supported which is the default encoding for JSON according to [RFC 8259](https://tools.ietf.org/html/rfc8259.html#section-8.1).
+- Only **UTF-8** encoded input is supported, which is the default encoding for JSON according to [RFC 8259](https://tools.ietf.org/html/rfc8259.html#section-8.1).
 - `std::u16string` and `std::u32string` can be parsed, assuming UTF-16 and UTF-32 encoding, respectively. These encodings are not supported when reading from files or other input containers.
 - Other encodings such as Latin-1 or ISO 8859-1 are **not** supported and will yield parse or serialization errors.
 - [Unicode noncharacters](https://www.unicode.org/faq/private_use.html#nonchar1) will not be replaced by the library.
@@ -1801,7 +1801,17 @@ This library does not support comments by default. It does so for three reasons:
   
 3. It is dangerous for interoperability if some libraries would add comment support while others don't. Please check [The Harmful Consequences of the Robustness Principle](https://tools.ietf.org/html/draft-iab-protocol-maintenance-01) on this.
 
-However, you can pass set parameter `ignore_comments` to true in the `parse` function to ignore `//` or `/* */` comments. Comments will then be treated as whitespace.
+However, you can set set parameter `ignore_comments` to true in the `parse` function to ignore `//` or `/* */` comments. Comments will then be treated as whitespace.
+
+### Trailing commas
+
+The JSON specification does not allow trailing commas in arrays and objects, and hence this library is treating them as parsing errors by default.
+
+Like comments, you can set parameter `ignore_trailing_commas` to true in the `parse` function to ignore trailing commas in arrays and objects. Note that a single comma as the only content of the array or object (`[,]` or `{,}`) is not allowed, and multiple trailing commas (`[1,,]`) are not allowed either.
+
+This library does not add trailing commas when serializing JSON data.
+
+For more information, see [JSON With Commas and Comments (JWCC)](https://nigeltao.github.io/blog/2021/json-with-commas-comments.html).
 
 ### Order of object keys
 

cmake/ci.cmake

@@ -659,6 +659,17 @@ add_custom_target(ci_cuda_example
     COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_cuda_example
 )
 
+###############################################################################
+# C++ 20 modules
+###############################################################################
+
+add_custom_target(ci_module_cpp20
+    COMMAND ${CMAKE_COMMAND}
+        -DCMAKE_BUILD_TYPE=Debug -GNinja
+        -S${PROJECT_SOURCE_DIR}/tests/module_cpp20 -B${PROJECT_BINARY_DIR}/ci_module_cpp20
+    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/ci_module_cpp20
+)
+
 ###############################################################################
 # Intel C++ Compiler
 ###############################################################################

cmake/detect_libcpp_version.cpp

@@ -0,0 +1,31 @@
+/*
+ * Detect used C++ Standard Library
+ *
+ * This file is compiled and run via try_run in download_test_data.cmake.
+ */
+
+#include <cstdio>
+
+// see https://en.cppreference.com/w/cpp/header/ciso646
+#if __cplusplus >= 202002L
+    #include <version>
+#else
+    #include <ciso646>
+#endif
+
+int main()
+{
+#if defined(_LIBCPP_VERSION)
+    std::printf("LLVM C++ Standard Library (libc++), _LIBCPP_VERSION=%d", _LIBCPP_VERSION);
+#elif defined(__GLIBCXX__)
+    std::printf("GNU C++ Standard Library (libstdc++), __GLIBCXX__=%d", __GLIBCXX__);
+#elif defined(_MSVC_STL_VERSION)
+    std::printf("Microsoft C++ Standard Library (MSVC STL), _MSVC_STL_VERSION=%d", _MSVC_STL_VERSION);
+#elif defined(_LIBCUDACXX_VERSION)
+    std::printf("NVIDIA C++ Standard Library (libcudacxx), _LIBCUDACXX_VERSION=%d", _LIBCUDACXX_VERSION);
+#elif defined(EASTL_VERSION)
+    std::printf("Electronic Arts Standard Template Library (EASTL), EASTL_VERSION=%d", EASTL_VERSION);
+#else
+    std::printf("unknown");
+#endif
+}

cmake/download_test_data.cmake

@@ -54,3 +54,18 @@ else()
 endif()
 string(REGEX REPLACE "[ ]*\n" "; " CXX_VERSION_RESULT "${CXX_VERSION_RESULT}")
 message(STATUS "Compiler: ${CXX_VERSION_RESULT}")
+
+# determine used C++ standard library (for debug and support purposes)
+if(NOT DEFINED LIBCPP_VERSION_OUTPUT_CACHED)
+    try_run(RUN_RESULT_VAR COMPILE_RESULT_VAR
+        "${CMAKE_BINARY_DIR}" SOURCES "${CMAKE_SOURCE_DIR}/cmake/detect_libcpp_version.cpp"
+        RUN_OUTPUT_VARIABLE LIBCPP_VERSION_OUTPUT COMPILE_OUTPUT_VARIABLE LIBCPP_VERSION_COMPILE_OUTPUT
+    )
+    if(NOT LIBCPP_VERSION_OUTPUT)
+        set(LIBCPP_VERSION_OUTPUT "Unknown")
+        message(AUTHOR_WARNING "Failed to compile cmake/detect_libcpp_version to detect the used C++ standard library. This does not affect the library or the test cases. Please still create an issue at https://github.com/nlohmann/json to investigate this.\n${LIBCPP_VERSION_COMPILE_OUTPUT}")
+    endif()
+    set(LIBCPP_VERSION_OUTPUT_CACHED "${LIBCPP_VERSION_OUTPUT}" CACHE STRING "Detected C++ standard library version")
+endif()
+
+message(STATUS "C++ standard library: ${LIBCPP_VERSION_OUTPUT_CACHED}")

cmake/gcc_flags.cmake

@@ -1,13 +1,13 @@
-# Warning flags determined for GCC 14.2.0 with https://github.com/nlohmann/gcc_flags:
+# Warning flags determined for GCC 15.1.0 with https://github.com/nlohmann/gcc_flags:
 # Ignored GCC warnings:
-# -Wno-abi-tag                    We do not care about ABI tags.
+# -Wno-abi-tag           We do not care about ABI tags.
-# -Wno-aggregate-return           The library uses aggregate returns.
+# -Wno-aggregate-return  The library uses aggregate returns.
-# -Wno-long-long                  The library uses the long long type to interface with system functions.
+# -Wno-long-long         The library uses the long long type to interface with system functions.
-# -Wno-namespaces                 The library uses namespaces.
+# -Wno-namespaces        The library uses namespaces.
-# -Wno-nrvo                       Doctest triggers this warning.
+# -Wno-nrvo              Doctest triggers this warning.
-# -Wno-padded                     We do not care about padding warnings.
+# -Wno-padded            We do not care about padding warnings.
-# -Wno-system-headers             We do not care about warnings in system headers.
+# -Wno-system-headers    We do not care about warnings in system headers.
-# -Wno-templates                  The library uses templates.
+# -Wno-templates         The library uses templates.
 
 set(GCC_CXXFLAGS
     -pedantic
@@ -65,6 +65,7 @@ set(GCC_CXXFLAGS
     -Wanalyzer-tainted-offset
     -Wanalyzer-tainted-size
     -Wanalyzer-too-complex
+    -Wanalyzer-undefined-behavior-ptrdiff
     -Wanalyzer-undefined-behavior-strtok
     -Wanalyzer-unsafe-call-within-signal-handler
     -Wanalyzer-use-after-free
@@ -123,6 +124,7 @@ set(GCC_CXXFLAGS
     -Wcoverage-invalid-line-number
     -Wcoverage-mismatch
     -Wcoverage-too-many-conditions
+    -Wcoverage-too-many-paths
     -Wcpp
     -Wctad-maybe-unsupported
     -Wctor-dtor-privacy
@@ -130,6 +132,7 @@ set(GCC_CXXFLAGS
     -Wdangling-pointer=2
     -Wdangling-reference
     -Wdate-time
+    -Wdefaulted-function-deleted
     -Wdelete-incomplete
     -Wdelete-non-virtual-dtor
     -Wdeprecated
@@ -138,6 +141,8 @@ set(GCC_CXXFLAGS
     -Wdeprecated-declarations
     -Wdeprecated-enum-enum-conversion
     -Wdeprecated-enum-float-conversion
+    -Wdeprecated-literal-operator
+    -Wdeprecated-variadic-comma-omission
     -Wdisabled-optimization
     -Wdiv-by-zero
     -Wdouble-promotion
@@ -157,20 +162,21 @@ set(GCC_CXXFLAGS
     -Wfloat-conversion
     -Wfloat-equal
     -Wformat -Wformat-contains-nul
+    -Wformat -Wformat-diag
     -Wformat -Wformat-extra-args
     -Wformat -Wformat-nonliteral
+    -Wformat -Wformat-overflow=2
     -Wformat -Wformat-security
+    -Wformat -Wformat-signedness
+    -Wformat -Wformat-truncation=2
     -Wformat -Wformat-y2k
     -Wformat -Wformat-zero-length
-    -Wformat-diag
-    -Wformat-overflow=2
-    -Wformat-signedness
-    -Wformat-truncation=2
     -Wformat=2
     -Wframe-address
     -Wfree-nonheap-object
     -Wglobal-module
     -Whardened
+    -Wheader-guard
     -Whsa
     -Wif-not-aligned
     -Wignored-attributes
@@ -197,6 +203,7 @@ set(GCC_CXXFLAGS
     -Wno-long-long
     -Wlto-type-mismatch
     -Wmain
+    -Wmaybe-musttail-local-addr
     -Wmaybe-uninitialized
     -Wmemset-elt-size
     -Wmemset-transposed-args
@@ -215,6 +222,7 @@ set(GCC_CXXFLAGS
     -Wmultichar
     -Wmultiple-inheritance
     -Wmultistatement-macros
+    -Wmusttail-local-addr
     -Wno-namespaces
     -Wnarrowing
     -Wnoexcept
@@ -245,6 +253,7 @@ set(GCC_CXXFLAGS
     -Wpmf-conversions
     -Wpointer-arith
     -Wpointer-compare
+    -Wpragma-once-outside-header
     -Wpragmas
     -Wprio-ctor-dtor
     -Wpsabi
@@ -276,10 +285,12 @@ set(GCC_CXXFLAGS
     -Wsizeof-pointer-div
     -Wsizeof-pointer-memaccess
     -Wstack-protector
+    -Wstrict-aliasing
     -Wstrict-aliasing=3
     -Wstrict-null-sentinel
     -Wstrict-overflow
     -Wstring-compare
+    -Wstringop-overflow
     -Wstringop-overflow=4
     -Wstringop-overread
     -Wstringop-truncation
@@ -304,8 +315,12 @@ set(GCC_CXXFLAGS
     -Wsynth
     -Wno-system-headers
     -Wtautological-compare
+    -Wtemplate-body
+    -Wtemplate-id-cdtor
+    -Wtemplate-names-tu-local
     -Wno-templates
     -Wterminate
+    -Wtrailing-whitespace
     -Wtrampolines
     -Wtrigraphs
     -Wtrivial-auto-var-init

cmake/requirements/requirements-cpplint.txt

@@ -1 +1 @@
-cpplint==2.0.1
+cpplint==2.0.2

docs/docset/docset.json

@@ -1,6 +1,6 @@
 {
   "name": "JSON for Modern C++",
-  "version": "3.11.3",
+  "version": "3.12.0",
   "archive": "JSON_for_Modern_C++.tgz",
   "author": {
     "name": "Niels Lohmann",

docs/mkdocs/docs/api/adl_serializer/index.md

@@ -8,7 +8,7 @@ struct adl_serializer;
 Serializer that uses ADL ([Argument-Dependent Lookup](https://en.cppreference.com/w/cpp/language/adl)) to choose
 `to_json`/`from_json` functions from the types' namespaces.
 
-It is implemented similar to
+It is implemented similarly to
 
 ```cpp
 template<typename ValueType>

docs/mkdocs/docs/api/basic_json/accept.md

@@ -4,12 +4,14 @@
 // (1)
 template<typename InputType>
 static bool accept(InputType&& i,
-                   const bool ignore_comments = false);
+                   const bool ignore_comments = false,
+                   const bool ignore_trailing_commas = false);
 
 // (2)
 template<typename IteratorType>
 static bool accept(IteratorType first, IteratorType last,
-                   const bool ignore_comments = false);
+                   const bool ignore_comments = false,
+                   const bool ignore_trailing_commas = false);
 ```
 
 Checks whether the input is valid JSON.
@@ -50,6 +52,10 @@ Unlike the [`parse()`](parse.md) function, this function neither throws an excep
 :   whether comments should be ignored and treated like whitespace (`#!cpp true`) or yield a parse error
     (`#!cpp false`); (optional, `#!cpp false` by default)
 
+`ignore_trailing_commas` (in)
+:   whether trailing commas in arrays or objects should be ignored and treated like whitespace (`#!cpp true`) or yield a parse error
+    (`#!cpp false`); (optional, `#!cpp false` by default)
+
 `first` (in)
 :   iterator to the start of the character range
 
@@ -102,6 +108,7 @@ A UTF-8 byte order mark is silently ignored.
 - Added in version 3.0.0.
 - Ignoring comments via `ignore_comments` added in version 3.9.0.
 - Changed [runtime assertion](../../features/assertions.md) in case of `FILE*` null pointers to exception in version 3.12.0.
+- Added `ignore_trailing_commas` in version 3.12.1.
 
 !!! warning "Deprecation"
 

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

@@ -74,7 +74,7 @@ basic_json(basic_json&& other) noexcept;
     - **boolean**: `boolean_t` / `bool` can be used.
     - **binary**: `binary_t` / `std::vector<uint8_t>` may be used; unfortunately because string literals cannot be
      distinguished from binary character arrays by the C++ type system, all types compatible with `const char*` will be
-     directed to the string constructor instead. This is both for backwards compatibility, and due to the fact that a
+     directed to the string constructor instead. This is both for backwards compatibility and due to the fact that a
      binary type is not a standard JSON type.
     
     See the examples below.

docs/mkdocs/docs/api/basic_json/empty.md

@@ -4,7 +4,7 @@
 bool empty() const noexcept;
 ```
 
-Checks if a JSON value has no elements (i.e. whether its [`size()`](size.md) is `0`).
+Checks if a JSON value has no elements (i.e., whether its [`size()`](size.md) is `0`).
     
 ## Return value
 

docs/mkdocs/docs/api/basic_json/insert.md

@@ -29,11 +29,11 @@ void insert(const_iterator first, const_iterator last);
 For all cases where an element is added to an **array**, a reallocation can happen, in which case all iterators
 (including the [`end()`](end.md) iterator) and all references to the elements are invalidated. Otherwise, only the
 [`end()`](end.md) iterator is invalidated. Also, any iterator or reference after the insertion point will point to the
-same index which is now a different value.
+same index, which is now a different value.
 
 For [`ordered_json`](../ordered_json.md), also adding an element to an **object** can yield a reallocation which again
 invalidates all iterators and all references. Also, any iterator or reference after the insertion point will point to
-the same index which is now a different value.
+the same index, which is now a different value.
 
 ## Parameters
 

docs/mkdocs/docs/api/basic_json/json_base_class_t.md

@@ -16,7 +16,7 @@ Examples of such functionality might be metadata, additional member functions (e
 
 #### Default type
 
-The default value for `CustomBaseClass` is `void`. In this case an
+The default value for `CustomBaseClass` is `void`. In this case, an
 [empty base class](https://en.cppreference.com/w/cpp/language/ebo) is used and no additional functionality is injected.
 
 #### Limitations

docs/mkdocs/docs/api/basic_json/parse.md

@@ -6,14 +6,16 @@ template<typename InputType>
 static basic_json parse(InputType&& i,
                         const parser_callback_t cb = nullptr,
                         const bool allow_exceptions = true,
-                        const bool ignore_comments = false);
+                        const bool ignore_comments = false,
+                        const bool ignore_trailing_commas = false);
 
 // (2)
 template<typename IteratorType>
 static basic_json parse(IteratorType first, IteratorType last,
                         const parser_callback_t cb = nullptr,
                         const bool allow_exceptions = true,
-                        const bool ignore_comments = false);
+                        const bool ignore_comments = false,
+                        const bool ignore_trailing_commas = false);
 ```
 
 1. Deserialize from a compatible input.
@@ -56,6 +58,10 @@ static basic_json parse(IteratorType first, IteratorType last,
 :   whether comments should be ignored and treated like whitespace (`#!cpp true`) or yield a parse error
     (`#!cpp false`); (optional, `#!cpp false` by default)
 
+`ignore_trailing_commas` (in)
+:   whether trailing commas in arrays or objects should be ignored and treated like whitespace (`#!cpp true`) or yield a parse error
+    (`#!cpp false`); (optional, `#!cpp false` by default)
+
 `first` (in)
 :   iterator to the start of a character range
 
@@ -189,6 +195,34 @@ A UTF-8 byte order mark is silently ignored.
     --8<-- "examples/parse__allow_exceptions.output"
     ```
 
+??? example "Effect of `ignore_comments` parameter"
+
+    The example below demonstrates the effect of the `ignore_comments` parameter in the `parse()` function.
+
+    ```cpp
+    --8<-- "examples/comments.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/comments.output"
+    ```
+
+??? example "Effect of `ignore_trailing_commas` parameter"
+
+    The example below demonstrates the effect of the `ignore_trailing_commas` parameter in the `parse()` function.
+
+    ```cpp
+    --8<-- "examples/trailing_commas.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/trailing_commas.output"
+    ```
+
 ## See also
 
 - [accept](accept.md) - check if the input is valid JSON
@@ -200,6 +234,7 @@ A UTF-8 byte order mark is silently ignored.
 - Overload for contiguous containers (1) added in version 2.0.3.
 - Ignoring comments via `ignore_comments` added in version 3.9.0.
 - Changed [runtime assertion](../../features/assertions.md) in case of `FILE*` null pointers to exception in version 3.12.0.
+- Added `ignore_trailing_commas` in version 3.12.1.
 
 !!! warning "Deprecation"
 

docs/mkdocs/docs/api/basic_json/sax_parse.md

@@ -7,7 +7,8 @@ static bool sax_parse(InputType&& i,
                       SAX* sax,
                       input_format_t format = input_format_t::json,
                       const bool strict = true,
-                      const bool ignore_comments = false);
+                      const bool ignore_comments = false,
+                      const bool ignore_trailing_commas = false);
 
 // (2)
 template<class IteratorType, class SAX>
@@ -15,7 +16,8 @@ static bool sax_parse(IteratorType first, IteratorType last,
                       SAX* sax,
                       input_format_t format = input_format_t::json,
                       const bool strict = true,
-                      const bool ignore_comments = false);
+                      const bool ignore_comments = false,
+                      const bool ignore_trailing_commas = false);
 ```
 
 Read from input and generate SAX events
@@ -65,6 +67,10 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
 :   whether comments should be ignored and treated like whitespace (`#!cpp true`) or yield a parse error
     (`#!cpp false`); (optional, `#!cpp false` by default)
 
+`ignore_trailing_commas` (in)
+:   whether trailing commas in arrays or objects should be ignored and treated like whitespace (`#!cpp true`) or yield a parse error
+    (`#!cpp false`); (optional, `#!cpp false` by default)
+
 `first` (in)
 :   iterator to the start of a character range
 
@@ -107,6 +113,7 @@ A UTF-8 byte order mark is silently ignored.
 
 - Added in version 3.2.0.
 - Ignoring comments via `ignore_comments` added in version 3.9.0.
+- Added `ignore_trailing_commas` in version 3.12.1.
 
 !!! warning "Deprecation"
 

docs/mkdocs/docs/api/macros/nlohmann_define_derived_type.md

@@ -79,7 +79,7 @@ template<typename BasicJsonType>
 void from_json(const BasicJsonType&, type&);
 ```
 
-Macros 3 and 6 add one function to the namespace which takes care of the serialization only:
+Macros 3 and 6 add one function to the namespace, which takes care of the serialization only:
 
 ```cpp
 template<typename BasicJsonType>

docs/mkdocs/docs/api/macros/nlohmann_define_type_intrusive.md

@@ -46,7 +46,7 @@ template<typename BasicJsonType>
 friend void from_json(const BasicJsonType&, type&); // except (3)
 ```
 
-See examples below for the concrete generated code.
+See the examples below for the concrete generated code.
 
 ## Notes
 

docs/mkdocs/docs/api/macros/nlohmann_define_type_non_intrusive.md

@@ -46,7 +46,7 @@ template<typename BasicJsonType>
 void from_json(const BasicJsonType&, type&); // except (3)
 ```
 
-See examples below for the concrete generated code.
+See the examples below for the concrete generated code.
 
 ## Notes
 

docs/mkdocs/docs/api/macros/nlohmann_json_serialize_enum.md

@@ -4,8 +4,8 @@
 #define NLOHMANN_JSON_SERIALIZE_ENUM(type, conversion...)
 ```
 
-By default, enum values are serialized to JSON as integers. In some cases this could result in undesired behavior. If an
+By default, enum values are serialized to JSON as integers. In some cases, this could result in undesired behavior. If
-enum is modified or re-ordered after data has been serialized to JSON, the later deserialized JSON data may be
+an enum is modified or re-ordered after data has been serialized to JSON, the later deserialized JSON data may be
 undefined or a different enum value than was originally intended.
 
 The `NLOHMANN_JSON_SERIALIZE_ENUM` allows to define a user-defined serialization for every enumerator.

docs/mkdocs/docs/api/ordered_json.md

@@ -11,7 +11,7 @@ This type preserves the insertion order of object keys.
 The type is based on [`ordered_map`](ordered_map.md) which in turn uses a `std::vector` to store object elements.
 Therefore, adding object elements can yield a reallocation in which case all iterators (including the
 [`end()`](basic_json/end.md) iterator) and all references to the elements are invalidated. Also, any iterator or
-reference after the insertion point will point to the same index which is now a different value.
+reference after the insertion point will point to the same index, which is now a different value.
 
 ## Examples
 

docs/mkdocs/docs/community/quality_assurance.md

@@ -57,6 +57,7 @@ violations will result in a failed build.
         | Clang 19.1.7                                 | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
         | Clang 20.1.1                                 | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
         | Clang 21.0.0                                 | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
+        | Emscripten 4.0.6                             | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
         | GNU 4.8.5                                    | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
         | GNU 4.9.3                                    | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
         | GNU 5.5.0                                    | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
@@ -75,6 +76,8 @@ violations will result in a failed build.
         | GNU 13.3.0                                   | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
         | GNU 14.2.0                                   | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
         | GNU 14.2.0                                   | arm64        | Linux 6.1.100            | Cirrus CI |
+        | GNU 15.1.0                                   | x86_64       | Ubuntu 22.04.1 LTS       | GitHub    |
+        | icpc (ICC) 2021.5.0 20211109                 | x86_64       | Ubuntu 20.04.3 LTS       | GitHub    |
         | MSVC 19.0.24241.7                            | x86          | Windows 8.1              | AppVeyor  |
         | MSVC 19.16.27035.0                           | x86          | Windows-10 (Build 14393) | AppVeyor  |
         | MSVC 19.29.30157.0                           | x86          | Windows 10 (Build 17763) | GitHub    |

docs/mkdocs/docs/examples/comments.cpp

@@ -0,0 +1,31 @@
+
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::string s = R"(
+    {
+        // update in 2006: removed Pluto
+        "planets": ["Mercury", "Venus", "Earth", "Mars",
+                    "Jupiter", "Uranus", "Neptune" /*, "Pluto" */]
+    }
+    )";
+
+    try
+    {
+        json j = json::parse(s);
+    }
+    catch (json::exception& e)
+    {
+        std::cout << e.what() << std::endl;
+    }
+
+    json j = json::parse(s,
+                         /* callback */ nullptr,
+                         /* allow exceptions */ true,
+                         /* ignore_comments */ true);
+    std::cout << j.dump(2) << '\n';
+}

docs/mkdocs/docs/examples/comments.output

@@ -0,0 +1,12 @@
+[json.exception.parse_error.101] parse error at line 3, column 9: syntax error while parsing object key - invalid literal; last read: '<U+000A>    {<U+000A>        /'; expected string literal
+{
+  "planets": [
+    "Mercury",
+    "Venus",
+    "Earth",
+    "Mars",
+    "Jupiter",
+    "Uranus",
+    "Neptune"
+  ]
+}

docs/mkdocs/docs/examples/meta.output

@@ -2,16 +2,16 @@
     "compiler": {
         "c++": "201103",
         "family": "gcc",
-        "version": "12.3.0"
+        "version": "12.4.0"
     },
-    "copyright": "(C) 2013-2022 Niels Lohmann",
+    "copyright": "(C) 2013-2025 Niels Lohmann",
     "name": "JSON for Modern C++",
     "platform": "apple",
     "url": "https://github.com/nlohmann/json",
     "version": {
         "major": 3,
-        "minor": 11,
+        "minor": 12,
-        "patch": 3,
+        "patch": 0,
-        "string": "3.11.3"
+        "string": "3.12.0"
     }
 }

docs/mkdocs/docs/examples/nlohmann_json_namespace.output

@@ -1 +1 @@
-nlohmann::json_abi_v3_11_3
+nlohmann::json_abi_v3_12_0

docs/mkdocs/docs/examples/nlohmann_json_version.output

@@ -1 +1 @@
-JSON for Modern C++ version 3.11.3
+JSON for Modern C++ version 3.12.0

docs/mkdocs/docs/examples/trailing_commas.cpp

@@ -0,0 +1,37 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::string s = R"(
+    {
+        "planets": [
+            "Mercury",
+            "Venus",
+            "Earth",
+            "Mars",
+            "Jupiter",
+            "Uranus",
+            "Neptune",
+        ]
+    }
+    )";
+
+    try
+    {
+        json j = json::parse(s);
+    }
+    catch (json::exception& e)
+    {
+        std::cout << e.what() << std::endl;
+    }
+
+    json j = json::parse(s,
+                         /* callback */ nullptr,
+                         /* allow exceptions */ true,
+                         /* ignore_comments */ false,
+                         /* ignore_trailing_commas */ true);
+    std::cout << j.dump(2) << '\n';
+}

docs/mkdocs/docs/examples/trailing_commas.output

@@ -0,0 +1,12 @@
+[json.exception.parse_error.101] parse error at line 11, column 9: syntax error while parsing value - unexpected ']'; expected '[', '{', or a literal
+{
+  "planets": [
+    "Mercury",
+    "Venus",
+    "Earth",
+    "Mars",
+    "Jupiter",
+    "Uranus",
+    "Neptune"
+  ]
+}

docs/mkdocs/docs/features/binary_formats/cbor.md

@@ -1,7 +1,7 @@
 # CBOR
 
-The Concise Binary Object Representation (CBOR) is a data format whose design goals include the possibility of extremely
+The Concise Binary Object Representation (CBOR) is a data format whose design goals include the possibility of
-small code size, fairly small message size, and extensibility without the need for version negotiation.
+extremely small code sizes, fairly small message size, and extensibility without the need for version negotiation.
 
 !!! abstract "References"
 

docs/mkdocs/docs/features/binary_values.md

@@ -1,7 +1,7 @@
 # Binary Values
 
 The library implements several [binary formats](binary_formats/index.md) that encode JSON in an efficient way. Most of
-these formats support binary values; that is, values that have semantics define outside the library and only define a
+these formats support binary values; that is, values that have semantics defined outside the library and only define a
 sequence of bytes to be stored.
 
 JSON itself does not have a binary value. As such, binary values are an extension that this library implements to store
@@ -189,7 +189,7 @@ as an array of uint8 values. The library implements this translation.
 
 ### BSON
 
-[BSON](binary_formats/bson.md) supports binary values and subtypes. If a subtype is given, it is used and added as
+[BSON](binary_formats/bson.md) supports binary values and subtypes. If a subtype is given, it is used and added as an
 unsigned 8-bit integer. If no subtype is given, the generic binary subtype 0x00 is used.
 
 ??? example
@@ -274,7 +274,7 @@ byte array.
 
 [MessagePack](binary_formats/messagepack.md) supports binary values and subtypes. If a subtype is given, the ext family
 is used. The library will choose the smallest representation among fixext1, fixext2, fixext4, fixext8, ext8, ext16, and
-ext32. The subtype is then added as signed 8-bit integer.
+ext32. The subtype is then added as a signed 8-bit integer.
 
 If no subtype is given, the bin family (bin8, bin16, bin32) is used.
 

docs/mkdocs/docs/features/comments.md

@@ -11,7 +11,9 @@ This library does not support comments *by default*. It does so for three reason
 
 3. It is dangerous for interoperability if some libraries add comment support while others do not. Please check [The Harmful Consequences of the Robustness Principle](https://tools.ietf.org/html/draft-iab-protocol-maintenance-01) on this.
 
-However, you can pass set parameter `ignore_comments` to `#!c true` in the parse function to ignore `//` or `/* */` comments. Comments will then be treated as whitespace.
+However, you can set parameter `ignore_comments` to `#!cpp true` in the [`parse`](../api/basic_json/parse.md) function to ignore `//` or `/* */` comments. Comments will then be treated as whitespace.
+
+For more information, see [JSON With Commas and Comments (JWCC)](https://nigeltao.github.io/blog/2021/json-with-commas-comments.html).
 
 !!! example
 
@@ -28,56 +30,11 @@ However, you can pass set parameter `ignore_comments` to `#!c true` in the parse
     When calling `parse` without additional argument, a parse error exception is thrown. If `ignore_comments` is set to `#! true`, the comments are ignored during parsing:
 
     ```cpp
-    #include <iostream>
+    --8<-- "examples/comments.cpp"
-    #include "json.hpp"
-    
-    using json = nlohmann::json;
-    
-    int main()
-    {
-        std::string s = R"(
-        {
-            // update in 2006: removed Pluto
-            "planets": ["Mercury", "Venus", "Earth", "Mars",
-                        "Jupiter", "Uranus", "Neptune" /*, "Pluto" */]
-        }
-        )";
-        
-        try
-        {
-            json j = json::parse(s);
-        }
-        catch (json::exception &e)
-        {
-            std::cout << e.what() << std::endl;
-        }
-        
-        json j = json::parse(s,
-                             /* callback */ nullptr,
-                             /* allow exceptions */ true,
-                             /* ignore_comments */ true);
-        std::cout << j.dump(2) << '\n';
-    }
     ```
 
     Output:
     
     ```
-    [json.exception.parse_error.101] parse error at line 3, column 9:
+    --8<-- "examples/comments.output"
-    syntax error while parsing object key - invalid literal;
-    last read: '<U+000A>    {<U+000A>        /'; expected string literal
-    ```
-    
-    ```json
-    {
-      "planets": [
-        "Mercury",
-        "Venus",
-        "Earth",
-        "Mars",
-        "Jupiter",
-        "Uranus",
-        "Neptune"
-      ]
-    }
     ```

docs/mkdocs/docs/features/enum_conversion.md

@@ -1,8 +1,8 @@
 # Specializing enum conversion
 
-By default, enum values are serialized to JSON as integers. In some cases this could result in undesired behavior. If an
+By default, enum values are serialized to JSON as integers. In some cases, this could result in undesired behavior. If
-enum is modified or re-ordered after data has been serialized to JSON, the later deserialized JSON data may be
+the integer values of any enum values are changed after data using those enum values has been serialized to JSON, then
-undefined or a different enum value than was originally intended.
+deserializing that JSON would result in a different enum value being restored, or the value not being found at all.
 
 It is possible to more precisely specify how a given enum is mapped to and from JSON as shown below:
 

docs/mkdocs/docs/features/iterators.md

@@ -37,7 +37,7 @@ When iterating over objects, values are ordered with respect to the `object_comp
     
     The reason for the order is the lexicographic ordering of the object keys "one", "three", "two".
 
-### Access object key during iteration
+### Access object keys during iteration
 
 The JSON iterators have two member functions, `key()` and `value()` to access the object key and stored value, respectively. When calling `key()` on a non-object iterator, an [invalid_iterator.207](../home/exceptions.md#jsonexceptioninvalid_iterator207) exception is thrown.
 

docs/mkdocs/docs/features/json_pointer.md

@@ -42,7 +42,7 @@ Note `/` does not identify the root (i.e., the whole document), but an object en
 JSON Pointers can be created from a string:
 
 ```cpp
-json::json_pointer p = "/nested/one";
+json::json_pointer p("/nested/one");
 ```
 
 Furthermore, a user-defined string literal can be used to achieve the same result:

docs/mkdocs/docs/features/namespace.md

@@ -64,7 +64,7 @@ configurations – to be used in cases where the linker would otherwise output u
 
 To do so, define [`NLOHMANN_JSON_NAMESPACE_NO_VERSION`](../api/macros/nlohmann_json_namespace_no_version.md) to `1`.
 
-This applies to version 3.11.2 and above only, versions 3.11.0 and 3.11.1 can apply the technique described in the next
+This applies to version 3.11.2 and above only; versions 3.11.0 and 3.11.1 can apply the technique described in the next
 section to emulate the effect of the `NLOHMANN_JSON_NAMESPACE_NO_VERSION` macro.
 
 !!! danger "Use at your own risk"

docs/mkdocs/docs/features/trailing_commas.md

@@ -0,0 +1,39 @@
+# Trailing Commas
+
+Like [comments](comments.md), this library does not support trailing commas in arrays and objects *by default*.
+
+You can set parameter `ignore_trailing_commas` to `#!cpp true` in the [`parse`](../api/basic_json/parse.md) function to allow trailing commas in arrays and objects. Note that a single comma as the only content of the array or object (`[,]` or `{,}`) is not allowed, and multiple trailing commas (`[1,,]`) are not allowed either.
+
+This library does not add trailing commas when serializing JSON data.
+
+For more information, see [JSON With Commas and Comments (JWCC)](https://nigeltao.github.io/blog/2021/json-with-commas-comments.html).
+
+!!! example
+
+    Consider the following JSON with trailing commas.
+
+    ```json
+    {
+        "planets": [
+            "Mercury",
+            "Venus",
+            "Earth",
+            "Mars",
+            "Jupiter",
+            "Uranus",
+            "Neptune",
+        ]
+    }
+    ```
+    
+    When calling `parse` without additional argument, a parse error exception is thrown. If `ignore_trailing_commas` is set to `#! true`, the trailing commas are ignored during parsing:
+
+    ```cpp
+    --8<-- "examples/trailing_commas.cpp"
+    ```
+
+    Output:
+    
+    ```
+    --8<-- "examples/trailing_commas.output"
+    ```

docs/mkdocs/docs/home/exceptions.md

@@ -520,7 +520,7 @@ The order of object iterators cannot be compared, because JSON objects are unord
 
 ### json.exception.invalid_iterator.214
 
-Cannot get value for iterator: Either the iterator belongs to a null value or it is an iterator to a primitive type (number, boolean, or string), but the iterator is different to `begin()`.
+Cannot retrieve value from iterator: The iterator either refers to a null value, or it refers to a primitive type (number, boolean, or string), but does not match the iterator returned by `begin()`.
 
 !!! failure "Example message"
 

docs/mkdocs/docs/home/faq.md

@@ -67,7 +67,7 @@ The library supports **Unicode input** as follows:
 - The strings stored in the library are UTF-8 encoded. When using the default string type (`std::string`), note that its length/size functions return the number of stored bytes rather than the number of characters or glyphs.
 - When you store strings with different encodings in the library, calling [`dump()`](https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a50ec80b02d0f3f51130d4abb5d1cfdc5.html#a50ec80b02d0f3f51130d4abb5d1cfdc5) may throw an exception unless `json::error_handler_t::replace` or `json::error_handler_t::ignore` are used as error handlers.
 
-In most cases, the parser is right to complain, because the input is not UTF-8 encoded. This is especially true for Microsoft Windows where Latin-1 or ISO 8859-1 is often the standard encoding.
+In most cases, the parser is right to complain, because the input is not UTF-8 encoded. This is especially true for Microsoft Windows, where Latin-1 or ISO 8859-1 is often the standard encoding.
 
 
 ### Wide string handling

docs/mkdocs/docs/home/releases.md

@@ -1071,7 +1071,7 @@ This release combines a lot of small fixes and improvements. The release is back
   - Improved the performance of the serialization by avoiding the re-creation of a locale object.
   - Fixed two MSVC warnings. Compiling the test suite with `/Wall` now only warns about non-inlined functions (C4710) and the deprecation of the constructor from input-stream (C4996).
 - Some project internals:
-  - <img align="right" src="https://bestpractices.coreinfrastructure.org/assets/questions_page_badge-17b338c0e8528d695d8676e23f39f17ca2b89bb88176370803ee69aeebcb5be4.png"> The project has qualified for the [Core Infrastructure Initiative Best Practices Badge](https://bestpractices.coreinfrastructure.org/projects/289). While most requirements where already satisfied, some led to a more explicit documentation of quality-ensuring procedures. For instance, static analysis is now executed with every commit on the build server. Furthermore, the [contribution guidelines document](https://github.com/nlohmann/json/blob/develop/.github/CONTRIBUTING.md) how to communicate security issues privately.
+  - <img align="right" src="https://bestpractices.coreinfrastructure.org/assets/questions_page_badge-17b338c0e8528d695d8676e23f39f17ca2b89bb88176370803ee69aeebcb5be4.png"> The project has qualified for the [Core Infrastructure Initiative Best Practices Badge](https://bestpractices.coreinfrastructure.org/projects/289). While most requirements where already satisfied, some led to more explicit documentation of quality-ensuring procedures. For instance, static analysis is now executed with every commit on the build server. Furthermore, the [contribution guidelines document](https://github.com/nlohmann/json/blob/develop/.github/CONTRIBUTING.md) how to communicate security issues privately.
   - The test suite has been overworked and split into several files to allow for faster compilation and analysis. The execute the test suite, simply execute `make check`.
   - The continuous integration with [Travis](https://travis-ci.org/nlohmann/json) was extended with Clang versions 3.6.0 to 3.8.1 and now includes 18 different compiler/OS combinations.
   - An 11-day run of [American fuzzy lop](http://lcamtuf.coredump.cx/afl/) checked 962 million inputs on the parser and found no issue.

docs/mkdocs/docs/integration/cmake.md

@@ -18,7 +18,7 @@ and use the namespaced imported target from the generated package configuration:
     cmake_minimum_required(VERSION 3.5)
     project(ExampleProject LANGUAGES CXX)
     
-    find_package(nlohmann_json 3.11.3 REQUIRED)
+    find_package(nlohmann_json 3.12.0 REQUIRED)
     
     add_executable(example example.cpp)
     target_link_libraries(example PRIVATE nlohmann_json::nlohmann_json)
@@ -77,7 +77,7 @@ to the following.
     
     ```cmake title="thirdparty/CMakeLists.txt"
     if(EXAMPLE_USE_EXTERNAL_JSON)
-        find_package(nlohmann_json 3.11.3 REQUIRED)
+        find_package(nlohmann_json 3.12.0 REQUIRED)
     else()
         set(JSON_BuildTests OFF CACHE INTERNAL "")
         add_subdirectory(nlohmann_json)
@@ -100,7 +100,7 @@ automatically download a release as a dependency at configure time.
 
     include(FetchContent)
     
-    FetchContent_Declare(json URL https://github.com/nlohmann/json/releases/download/v3.11.3/json.tar.xz)
+    FetchContent_Declare(json URL https://github.com/nlohmann/json/releases/download/v3.12.0/json.tar.xz)
     FetchContent_MakeAvailable(json)
     
     add_executable(example example.cpp)
@@ -115,7 +115,7 @@ automatically download a release as a dependency at configure time.
     ```cmake
     FetchContent_Declare(json
         GIT_REPOSITORY https://github.com/nlohmann/json
-        GIT_TAG v3.11.3
+        GIT_TAG v3.12.0
     )
     ```
 

docs/mkdocs/docs/integration/conan/Conanfile.txt

@@ -1,5 +1,5 @@
 [requires]
-nlohmann_json/3.11.3
+nlohmann_json/3.12.0
 
 [generators]
 CMakeToolchain

docs/mkdocs/docs/integration/cpm/CMakeLists.txt

@@ -3,7 +3,7 @@ project(json_example)
 
 include(${CMAKE_SOURCE_DIR}/cmake/CPM.cmake)
 
-CPMAddPackage("gh:nlohmann/json@3.11.3")
+CPMAddPackage("gh:nlohmann/json@3.12.0")
 
 add_executable(json_example example.cpp)
 target_link_libraries(json_example PRIVATE nlohmann_json::nlohmann_json)

docs/mkdocs/docs/integration/package_managers.md

@@ -398,7 +398,7 @@ If you are using [cget](http://cget.readthedocs.io/en/latest/), you can install
 cget install nlohmann/json
 ```
 
-A specific version can be installed with `cget install nlohmann/json@v3.11.3`. Also, the multiple header version can be
+A specific version can be installed with `cget install nlohmann/json@v3.12.0`. Also, the multiple header version can be
 installed by adding the `-DJSON_MultipleHeaders=ON` flag (i.e., `cget install nlohmann/json -DJSON_MultipleHeaders=ON`).
 
 ??? example
@@ -727,7 +727,7 @@ If you are using [`CPM.cmake`](https://github.com/TheLartians/CPM.cmake), add th
 [CPM.cmake script](https://github.com/TheLartians/CPM.cmake#adding-cpm) and the following snippet to your CMake project:
 
 ```cmake
-CPMAddPackage("gh:nlohmann/json@3.11.3")
+CPMAddPackage("gh:nlohmann/json@3.12.0")
 ```
 
 ??? example

docs/mkdocs/mkdocs.yml

@@ -67,6 +67,7 @@ nav:
           - features/binary_formats/ubjson.md
       - features/binary_values.md
       - features/comments.md
+      - features/trailing_commas.md
       - Element Access:
           - features/element_access/index.md
           - features/element_access/unchecked_access.md

docs/mkdocs/requirements.txt

@@ -2,7 +2,7 @@ wheel==0.45.1
 
 mkdocs==1.6.1                                       # documentation framework
 mkdocs-git-revision-date-localized-plugin==1.4.5    # plugin "git-revision-date-localized"
-mkdocs-material==9.6.11                             # theme for mkdocs
+mkdocs-material==9.6.14                             # theme for mkdocs
 mkdocs-material-extensions==1.3.1                   # extensions
 mkdocs-minify-plugin==0.8.0                         # plugin "minify"
 mkdocs-redirects==1.2.2                             # plugin "redirects"

include/nlohmann/adl_serializer.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/byte_container_with_subtype.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/abi_macros.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -12,15 +12,15 @@
 
 #ifndef JSON_SKIP_LIBRARY_VERSION_CHECK
     #if defined(NLOHMANN_JSON_VERSION_MAJOR) && defined(NLOHMANN_JSON_VERSION_MINOR) && defined(NLOHMANN_JSON_VERSION_PATCH)
-        #if NLOHMANN_JSON_VERSION_MAJOR != 3 || NLOHMANN_JSON_VERSION_MINOR != 11 || NLOHMANN_JSON_VERSION_PATCH != 3
+        #if NLOHMANN_JSON_VERSION_MAJOR != 3 || NLOHMANN_JSON_VERSION_MINOR != 12 || NLOHMANN_JSON_VERSION_PATCH != 0
             #warning "Already included a different version of the library!"
         #endif
     #endif
 #endif
 
 #define NLOHMANN_JSON_VERSION_MAJOR 3   // NOLINT(modernize-macro-to-enum)
-#define NLOHMANN_JSON_VERSION_MINOR 11  // NOLINT(modernize-macro-to-enum)
+#define NLOHMANN_JSON_VERSION_MINOR 12  // NOLINT(modernize-macro-to-enum)
-#define NLOHMANN_JSON_VERSION_PATCH 3   // NOLINT(modernize-macro-to-enum)
+#define NLOHMANN_JSON_VERSION_PATCH 0   // NOLINT(modernize-macro-to-enum)
 
 #ifndef JSON_DIAGNOSTICS
     #define JSON_DIAGNOSTICS 0

include/nlohmann/detail/conversions/from_json.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -13,9 +13,6 @@
 #include <forward_list> // forward_list
 #include <iterator> // inserter, front_inserter, end
 #include <map> // map
-#ifdef JSON_HAS_CPP_17
-    #include <optional> // optional
-#endif
 #include <string> // string
 #include <tuple> // tuple, make_tuple
 #include <type_traits> // is_arithmetic, is_same, is_enum, underlying_type, is_convertible
@@ -32,6 +29,15 @@
 #include <nlohmann/detail/string_concat.hpp>
 #include <nlohmann/detail/value_t.hpp>
 
+// include after macro_scope.hpp
+#ifdef JSON_HAS_CPP_17
+    #include <optional> // optional
+#endif
+
+#if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
+    #include <string_view> // u8string_view
+#endif
+
 NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
 {
@@ -47,7 +53,6 @@ inline void from_json(const BasicJsonType& j, typename std::nullptr_t& n)
 }
 
 #ifdef JSON_HAS_CPP_17
-#ifndef JSON_USE_IMPLICIT_CONVERSIONS
 template<typename BasicJsonType, typename T>
 void from_json(const BasicJsonType& j, std::optional<T>& opt)
 {
@@ -60,8 +65,6 @@ void from_json(const BasicJsonType& j, std::optional<T>& opt)
         opt.emplace(j.template get<T>());
     }
 }
-
-#endif // JSON_USE_IMPLICIT_CONVERSIONS
 #endif // JSON_HAS_CPP_17
 
 // overloads for basic_json template parameters
@@ -395,7 +398,7 @@ inline void from_json(const BasicJsonType& j, ConstructibleObjectType& obj)
 }
 
 // overload for arithmetic types, not chosen for basic_json template arguments
-// (BooleanType, etc..); note: Is it really necessary to provide explicit
+// (BooleanType, etc.); note: Is it really necessary to provide explicit
 // overloads for boolean_t etc. in case of a custom BooleanType which is not
 // an arithmetic type?
 template < typename BasicJsonType, typename ArithmeticType,
@@ -540,7 +543,10 @@ inline void from_json(const BasicJsonType& j, std_fs::path& p)
         JSON_THROW(type_error::create(302, concat("type must be string, but is ", j.type_name()), &j));
     }
     const auto& s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
-#ifdef JSON_HAS_CPP_20
+    // Checking for C++20 standard or later can be insufficient in case the
+    // library support for char8_t is either incomplete or was disabled
+    // altogether. Use the __cpp_lib_char8_t feature test instead.
+#if defined(__cpp_lib_char8_t) && (__cpp_lib_char8_t >= 201907L)
     p = std_fs::path(std::u8string_view(reinterpret_cast<const char8_t*>(s.data()), s.size()));
 #else
     p = std_fs::u8path(s); // accepts UTF-8 encoded std::string in C++17, deprecated in C++20

include/nlohmann/detail/conversions/to_chars.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2009 Florian Loitsch <https://florian.loitsch.com/>
@@ -130,7 +130,7 @@ struct diyfp // f * 2^e
         // p_lo = p0_lo + (Q << 32)
         //
         // But in this particular case here, the full p_lo is not required.
-        // Effectively we only need to add the highest bit in p_lo to p_hi (and
+        // Effectively, we only need to add the highest bit in p_lo to p_hi (and
         // Q_hi + 1 does not overflow).
 
         Q += std::uint64_t{1} << (64u - 32u - 1u); // round, ties up
@@ -220,7 +220,7 @@ boundaries compute_boundaries(FloatType value)
     // Compute the boundaries m- and m+ of the floating-point value
     // v = f * 2^e.
     //
-    // Determine v- and v+, the floating-point predecessor and successor if v,
+    // Determine v- and v+, the floating-point predecessor and successor of v,
     // respectively.
     //
     //      v- = v - 2^e        if f != 2^(p-1) or e == e_min                (A)
@@ -375,7 +375,7 @@ inline cached_power get_cached_power_for_binary_exponent(int e)
     // (A smaller distance gamma-alpha would require a larger table.)
 
     // NB:
-    // Actually this function returns c, such that -60 <= e_c + e + 64 <= -34.
+    // Actually, this function returns c, such that -60 <= e_c + e + 64 <= -34.
 
     constexpr int kCachedPowersMinDecExp = -300;
     constexpr int kCachedPowersDecStep = 8;
@@ -687,8 +687,8 @@ inline void grisu2_digit_gen(char* buffer, int& length, int& decimal_exponent,
 
             decimal_exponent += n;
 
-            // We may now just stop. But instead look if the buffer could be
+            // We may now just stop. But instead, it looks as if the buffer
-            // decremented to bring V closer to w.
+            // could be decremented to bring V closer to w.
             //
             // pow10 = 10^n is now 1 ulp in the decimal representation V.
             // The rounding procedure works with diyfp's with an implicit
@@ -1095,7 +1095,7 @@ char* to_chars(char* first, const char* last, FloatType value)
     // Compute v = buffer * 10^decimal_exponent.
     // The decimal digits are stored in the buffer, which needs to be interpreted
     // as an unsigned decimal integer.
-    // len is the length of the buffer, i.e. the number of decimal digits.
+    // len is the length of the buffer, i.e., the number of decimal digits.
     int len = 0;
     int decimal_exponent = 0;
     dtoa_impl::grisu2(first, len, decimal_exponent, value);

include/nlohmann/detail/conversions/to_json.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -15,7 +15,8 @@
 
 #include <algorithm> // copy
 #include <iterator> // begin, end
-#include <string> // string
+#include <memory> // allocator_traits
+#include <string> //  basic_string, char_traits
 #include <tuple> // tuple, get
 #include <type_traits> // is_same, is_constructible, is_floating_point, is_enum, underlying_type
 #include <utility> // move, forward, declval, pair
@@ -267,7 +268,7 @@ struct external_constructor<value_t::object>
 #ifdef JSON_HAS_CPP_17
 template<typename BasicJsonType, typename T,
          enable_if_t<std::is_constructible<BasicJsonType, T>::value, int> = 0>
-void to_json(BasicJsonType& j, const std::optional<T>& opt)
+void to_json(BasicJsonType& j, const std::optional<T>& opt) noexcept
 {
     if (opt.has_value())
     {
@@ -440,15 +441,21 @@ inline void to_json(BasicJsonType& j, const T& t)
 }
 
 #if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
+#if defined(__cpp_lib_char8_t)
+template<typename BasicJsonType, typename Tr, typename Allocator>
+inline void to_json(BasicJsonType& j, const std::basic_string<char8_t, Tr, Allocator>& s)
+{
+    using OtherAllocator = typename std::allocator_traits<Allocator>::template rebind_alloc<char>;
+    j = std::basic_string<char, std::char_traits<char>, OtherAllocator>(s.begin(), s.end(), s.get_allocator());
+}
+#endif
+
 template<typename BasicJsonType>
 inline void to_json(BasicJsonType& j, const std_fs::path& p)
 {
-#ifdef JSON_HAS_CPP_20
+    // Returns either a std::string or a std::u8string depending whether library
-    const std::u8string s = p.u8string();
+    // support for char8_t is enabled.
-    j = std::string(s.begin(), s.end());
+    j = p.u8string();
-#else
-    j = p.u8string(); // returns std::string in C++17
-#endif
 }
 #endif
 

include/nlohmann/detail/exceptions.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -30,7 +30,7 @@
 // emitted in every translation unit. This issue cannot be fixed with a
 // header-only library as there is no implementation file to move these
 // functions to. As a result, we suppress this warning here to avoid client
-// code to stumble over this. See https://github.com/nlohmann/json/issues/4087
+// code stumbling over this. See https://github.com/nlohmann/json/issues/4087
 // for a discussion.
 #if defined(__clang__)
     #pragma clang diagnostic push

include/nlohmann/detail/hash.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/input/binary_reader.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -53,7 +53,7 @@ enum class cbor_tag_handler_t
 
 @note from https://stackoverflow.com/a/1001328/266378
 */
-static inline bool little_endianness(int num = 1) noexcept
+inline bool little_endianness(int num = 1) noexcept
 {
     return *reinterpret_cast<char*>(&num) == 1;
 }
@@ -334,7 +334,7 @@ class binary_reader
                 return get_number<std::uint64_t, true>(input_format_t::bson, value) && sax->number_unsigned(value);
             }
 
-            default: // anything else not supported (yet)
+            default: // anything else is not supported (yet)
             {
                 std::array<char, 3> cr{{}};
                 static_cast<void>((std::snprintf)(cr.data(), cr.size(), "%.2hhX", static_cast<unsigned char>(element_type))); // NOLINT(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
@@ -731,7 +731,7 @@ class binary_reader
             case 0xD2:
             case 0xD3:
             case 0xD4:
-            case 0xD8: // tagged item (1 bytes follow)
+            case 0xD8: // tagged item (1 byte follows)
             case 0xD9: // tagged item (2 bytes follow)
             case 0xDA: // tagged item (4 bytes follow)
             case 0xDB: // tagged item (8 bytes follow)
@@ -783,7 +783,7 @@ class binary_reader
                     case cbor_tag_handler_t::store:
                     {
                         binary_t b;
-                        // use binary subtype and store in binary container
+                        // use binary subtype and store in a binary container
                         switch (current)
                         {
                             case 0xD8:
@@ -852,7 +852,7 @@ class binary_reader
                 const auto byte1 = static_cast<unsigned char>(byte1_raw);
                 const auto byte2 = static_cast<unsigned char>(byte2_raw);
 
-                // code from RFC 7049, Appendix D, Figure 3:
+                // Code from RFC 7049, 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
@@ -2159,7 +2159,7 @@ class binary_reader
                 {
                     break;
                 }
-                if (is_ndarray) // ndarray dimensional vector can only contain integers, and can not embed another array
+                if (is_ndarray) // ndarray dimensional vector can only contain integers and cannot embed another array
                 {
                     return sax->parse_error(chars_read, get_token_string(), parse_error::create(113, chars_read, exception_message(input_format, "ndarray dimensional vector is not allowed", "size"), nullptr));
                 }
@@ -2192,8 +2192,16 @@ 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))
+                        {
+                            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;
-                        if (result == 0 || result == npos) // because dim elements shall not have zeros, result = 0 means overflow happened; it also can't be npos as it is used to initialize size in get_ubjson_size_type()
+                        // Additional post-multiplication check to catch any edge cases the pre-check might miss
+                        if (result == 0 || 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));
                         }
@@ -2409,7 +2417,7 @@ class binary_reader
                 const auto byte1 = static_cast<unsigned char>(byte1_raw);
                 const auto byte2 = static_cast<unsigned char>(byte2_raw);
 
-                // code from RFC 7049, Appendix D, Figure 3:
+                // Code from RFC 7049, 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
@@ -2697,7 +2705,7 @@ class binary_reader
 
     bool get_ubjson_high_precision_number()
     {
-        // get size of following number string
+        // get the size of the following number string
         std::size_t size{};
         bool no_ndarray = true;
         auto res = get_ubjson_size_value(size, no_ndarray);
@@ -2795,7 +2803,7 @@ class binary_reader
         chars_read += new_chars_read;
         if (JSON_HEDLEY_UNLIKELY(new_chars_read < sizeof(T)))
         {
-            // in case of failure, advance position by 1 to report failing location
+            // in case of failure, advance position by 1 to report the failing location
             ++chars_read;
             sax->parse_error(chars_read, "<end of file>", parse_error::create(110, chars_read, exception_message(format, "unexpected end of input", context), nullptr));
             return false;
@@ -2826,17 +2834,22 @@ class binary_reader
         {
             return;
         }
-        if constexpr(std::is_integral_v<NumberType>)
+        else if constexpr(std::is_integral_v<NumberType>)
         {
             number = std::byteswap(number);
             return;
         }
-#endif
+        else
-        auto* ptr = reinterpret_cast<std::uint8_t*>(&number);
-        for (std::size_t i = 0; i < sz / 2; ++i)
         {
-            std::swap(ptr[i], ptr[sz - i - 1]);
+#endif
+            auto* ptr = reinterpret_cast<std::uint8_t*>(&number);
+            for (std::size_t i = 0; i < sz / 2; ++i)
+            {
+                std::swap(ptr[i], ptr[sz - i - 1]);
+            }
+#ifdef __cpp_lib_byteswap
         }
+#endif
     }
 
     /*

include/nlohmann/detail/input/input_adapters.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -108,7 +108,7 @@ class input_stream_adapter
         : is(&i), sb(i.rdbuf())
     {}
 
-    // delete because of pointer members
+    // deleted because of pointer members
     input_stream_adapter(const input_stream_adapter&) = delete;
     input_stream_adapter& operator=(input_stream_adapter&) = delete;
     input_stream_adapter& operator=(input_stream_adapter&&) = delete;
@@ -122,7 +122,7 @@ class input_stream_adapter
 
     // std::istream/std::streambuf use std::char_traits<char>::to_int_type, to
     // ensure that std::char_traits<char>::eof() and the character 0xFF do not
-    // end up as the same value, e.g. 0xFFFFFFFF.
+    // end up as the same value, e.g., 0xFFFFFFFF.
     std::char_traits<char>::int_type get_character()
     {
         auto res = sb->sbumpc();
@@ -344,7 +344,7 @@ class wide_string_input_adapter
 
     typename std::char_traits<char>::int_type get_character() noexcept
     {
-        // check if buffer needs to be filled
+        // check if the buffer needs to be filled
         if (utf8_bytes_index == utf8_bytes_filled)
         {
             fill_buffer<sizeof(WideCharType)>();

include/nlohmann/detail/input/json_sax.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -260,7 +260,7 @@ class json_sax_dom_parser
         JSON_ASSERT(!ref_stack.empty());
         JSON_ASSERT(ref_stack.back()->is_object());
 
-        // add null at given key and store the reference for later
+        // add null at the given key and store the reference for later
         object_element = &(ref_stack.back()->m_data.m_value.object->operator[](val));
         return true;
     }
@@ -576,11 +576,11 @@ class json_sax_dom_callback_parser
     {
         BasicJsonType k = BasicJsonType(val);
 
-        // check callback for key
+        // check callback for the key
         const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::key, k);
         key_keep_stack.push_back(keep);
 
-        // add discarded value at given key and store the reference for later
+        // add discarded value at the given key and store the reference for later
         if (keep && ref_stack.back())
         {
             object_element = &(ref_stack.back()->m_data.m_value.object->operator[](val) = discarded);

include/nlohmann/detail/input/lexer.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -127,7 +127,7 @@ class lexer : public lexer_base<BasicJsonType>
         , decimal_point_char(static_cast<char_int_type>(get_decimal_point()))
     {}
 
-    // delete because of pointer members
+    // deleted because of pointer members
     lexer(const lexer&) = delete;
     lexer(lexer&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor)
     lexer& operator=(lexer&) = delete;
@@ -262,10 +262,10 @@ class lexer : public lexer_base<BasicJsonType>
 
         while (true)
         {
-            // get next character
+            // get the next character
             switch (get())
             {
-                // end of file while parsing string
+                // end of file while parsing the string
                 case char_traits<char_type>::eof():
                 {
                     error_message = "invalid string: missing closing quote";
@@ -351,7 +351,7 @@ class lexer : public lexer_base<BasicJsonType>
                                                         (static_cast<unsigned int>(codepoint1) << 10u)
                                                         // low surrogate occupies the least significant 15 bits
                                                         + static_cast<unsigned int>(codepoint2)
-                                                        // there is still the 0xD800, 0xDC00 and 0x10000 noise
+                                                        // there is still the 0xD800, 0xDC00, and 0x10000 noise
                                                         // in the result, so we have to subtract with:
                                                         // (0xD800 << 10) + DC00 - 0x10000 = 0x35FDC00
                                                         - 0x35FDC00u);
@@ -377,7 +377,7 @@ class lexer : public lexer_base<BasicJsonType>
                                 }
                             }
 
-                            // result of the above calculation yields a proper codepoint
+                            // the result of the above calculation yields a proper codepoint
                             JSON_ASSERT(0x00 <= codepoint && codepoint <= 0x10FFFF);
 
                             // translate codepoint into bytes
@@ -828,7 +828,7 @@ class lexer : public lexer_base<BasicJsonType>
                     break;
                 }
 
-                // remaining bytes (80..C1 and F5..FF) are ill-formed
+                // the remaining bytes (80..C1 and F5..FF) are ill-formed
                 default:
                 {
                     error_message = "invalid string: ill-formed UTF-8 byte";
@@ -973,7 +973,7 @@ class lexer : public lexer_base<BasicJsonType>
         reset();
 
         // the type of the parsed number; initially set to unsigned; will be
-        // changed if minus sign, decimal point or exponent is read
+        // changed if minus sign, decimal point, or exponent is read
         token_type number_type = token_type::value_unsigned;
 
         // state (init): we just found out we need to scan a number
@@ -1345,7 +1345,7 @@ scan_number_done:
 
         if (next_unget)
         {
-            // just reset the next_unget variable and work with current
+            // only reset the next_unget variable and work with current
             next_unget = false;
         }
         else
@@ -1524,7 +1524,7 @@ scan_number_done:
             return token_type::parse_error;
         }
 
-        // read next character and ignore whitespace
+        // read the next character and ignore whitespace
         skip_whitespace();
 
         // ignore comments

include/nlohmann/detail/input/parser.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -71,10 +71,12 @@ class parser
     explicit parser(InputAdapterType&& adapter,
                     parser_callback_t<BasicJsonType> cb = nullptr,
                     const bool allow_exceptions_ = true,
-                    const bool skip_comments = false)
+                    const bool ignore_comments = false,
+                    const bool ignore_trailing_commas_ = false)
         : callback(std::move(cb))
-        , m_lexer(std::move(adapter), skip_comments)
+        , m_lexer(std::move(adapter), ignore_comments)
         , allow_exceptions(allow_exceptions_)
+        , ignore_trailing_commas(ignore_trailing_commas_)
     {
         // read first token
         get_token();
@@ -106,7 +108,7 @@ class parser
                                                     exception_message(token_type::end_of_input, "value"), nullptr));
             }
 
-            // in case of an error, return discarded value
+            // in case of an error, return a discarded value
             if (sdp.is_errored())
             {
                 result = value_t::discarded;
@@ -133,7 +135,7 @@ class parser
                                 parse_error::create(101, m_lexer.get_position(), exception_message(token_type::end_of_input, "value"), nullptr));
             }
 
-            // in case of an error, return discarded value
+            // in case of an error, return a discarded value
             if (sdp.is_errored())
             {
                 result = value_t::discarded;
@@ -336,7 +338,7 @@ class parser
 
                     case token_type::parse_error:
                     {
-                        // using "uninitialized" to avoid "expected" message
+                        // using "uninitialized" to avoid an "expected" message
                         return sax->parse_error(m_lexer.get_position(),
                                                 m_lexer.get_token_string(),
                                                 parse_error::create(101, m_lexer.get_position(), exception_message(token_type::uninitialized, "value"), nullptr));
@@ -384,11 +386,17 @@ class parser
             if (states.back())  // array
             {
                 // comma -> next value
+                // or end of array (ignore_trailing_commas = true)
                 if (get_token() == token_type::value_separator)
                 {
                     // parse a new value
                     get_token();
-                    continue;
+
+                    // if ignore_trailing_commas and last_token is ], we can continue to "closing ]"
+                    if (!(ignore_trailing_commas && last_token == token_type::end_array))
+                    {
+                        continue;
+                    }
                 }
 
                 // closing ]
@@ -417,32 +425,39 @@ class parser
             // states.back() is false -> object
 
             // comma -> next value
+            // or end of object (ignore_trailing_commas = true)
             if (get_token() == token_type::value_separator)
             {
-                // parse key
-                if (JSON_HEDLEY_UNLIKELY(get_token() != token_type::value_string))
-                {
-                    return sax->parse_error(m_lexer.get_position(),
-                                            m_lexer.get_token_string(),
-                                            parse_error::create(101, m_lexer.get_position(), exception_message(token_type::value_string, "object key"), nullptr));
-                }
-
-                if (JSON_HEDLEY_UNLIKELY(!sax->key(m_lexer.get_string())))
-                {
-                    return false;
-                }
-
-                // parse separator (:)
-                if (JSON_HEDLEY_UNLIKELY(get_token() != token_type::name_separator))
-                {
-                    return sax->parse_error(m_lexer.get_position(),
-                                            m_lexer.get_token_string(),
-                                            parse_error::create(101, m_lexer.get_position(), exception_message(token_type::name_separator, "object separator"), nullptr));
-                }
-
-                // parse values
                 get_token();
-                continue;
+
+                // if ignore_trailing_commas and last_token is }, we can continue to "closing }"
+                if (!(ignore_trailing_commas && last_token == token_type::end_object))
+                {
+                    // parse key
+                    if (JSON_HEDLEY_UNLIKELY(last_token != token_type::value_string))
+                    {
+                        return sax->parse_error(m_lexer.get_position(),
+                                                m_lexer.get_token_string(),
+                                                parse_error::create(101, m_lexer.get_position(), exception_message(token_type::value_string, "object key"), nullptr));
+                    }
+
+                    if (JSON_HEDLEY_UNLIKELY(!sax->key(m_lexer.get_string())))
+                    {
+                        return false;
+                    }
+
+                    // parse separator (:)
+                    if (JSON_HEDLEY_UNLIKELY(get_token() != token_type::name_separator))
+                    {
+                        return sax->parse_error(m_lexer.get_position(),
+                                                m_lexer.get_token_string(),
+                                                parse_error::create(101, m_lexer.get_position(), exception_message(token_type::name_separator, "object separator"), nullptr));
+                    }
+
+                    // parse values
+                    get_token();
+                    continue;
+                }
             }
 
             // closing }
@@ -513,6 +528,8 @@ class parser
     lexer_t m_lexer;
     /// whether to throw exceptions in case of errors
     const bool allow_exceptions = true;
+    /// whether trailing commas in objects and arrays should be ignored (true) or signaled as errors (false)
+    const bool ignore_trailing_commas = false;
 };
 
 }  // namespace detail

include/nlohmann/detail/input/position_t.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/iterators/internal_iterator.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/iterators/iter_impl.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -23,7 +23,7 @@ NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
 {
 
-// forward declare, to be able to friend it later on
+// forward declare to be able to friend it later on
 template<typename IteratorType> class iteration_proxy;
 template<typename IteratorType> class iteration_proxy_value;
 

include/nlohmann/detail/iterators/iteration_proxy.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/iterators/iterator_traits.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/iterators/json_reverse_iterator.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/iterators/primitive_iterator.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -21,9 +21,9 @@ namespace detail
 @brief an iterator for primitive JSON types
 
 This class models an iterator for primitive JSON types (boolean, number,
-string). It's only purpose is to allow the iterator/const_iterator classes
+string). Its only purpose is to allow the iterator/const_iterator classes
 to "iterate" over primitive values. Internally, the iterator is modeled by
-a `difference_type` variable. Value begin_value (`0`) models the begin,
+a `difference_type` variable. Value begin_value (`0`) models the begin and
 end_value (`1`) models past the end.
 */
 class primitive_iterator_t

include/nlohmann/detail/json_custom_base_class.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/json_pointer.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -285,7 +285,7 @@ class json_pointer
                 {
                     if (reference_token == "0")
                     {
-                        // start a new array if reference token is 0
+                        // start a new array if the reference token is 0
                         result = &result->operator[](0);
                     }
                     else
@@ -314,7 +314,7 @@ class json_pointer
                 The following code is only reached if there exists a reference
                 token _and_ the current value is primitive. In this case, we have
                 an error situation, because primitive values may only occur as
-                single value; that is, with an empty list of reference tokens.
+                a single value; that is, with an empty list of reference tokens.
                 */
                 case detail::value_t::string:
                 case detail::value_t::boolean:
@@ -358,7 +358,7 @@ class json_pointer
             // convert null values to arrays or objects before continuing
             if (ptr->is_null())
             {
-                // check if reference token is a number
+                // check if the reference token is a number
                 const bool nums =
                     std::all_of(reference_token.begin(), reference_token.end(),
                                 [](const unsigned char x)
@@ -366,7 +366,7 @@ class json_pointer
                     return std::isdigit(x);
                 });
 
-                // change value to array for numbers or "-" or to object otherwise
+                // change value to an array for numbers or "-" or to object otherwise
                 *ptr = (nums || reference_token == "-")
                        ? detail::value_t::array
                        : detail::value_t::object;
@@ -609,7 +609,7 @@ class json_pointer
                     {
                         if (JSON_HEDLEY_UNLIKELY(!('1' <= reference_token[0] && reference_token[0] <= '9')))
                         {
-                            // first char should be between '1' and '9'
+                            // the first char should be between '1' and '9'
                             return false;
                         }
                         for (std::size_t i = 1; i < reference_token.size(); i++)
@@ -673,7 +673,7 @@ class json_pointer
             return result;
         }
 
-        // check if nonempty reference string begins with slash
+        // check if a nonempty reference string begins with slash
         if (JSON_HEDLEY_UNLIKELY(reference_string[0] != '/'))
         {
             JSON_THROW(detail::parse_error::create(107, 1, detail::concat("JSON pointer must be empty or begin with '/' - was: '", reference_string, "'"), nullptr));
@@ -747,7 +747,7 @@ class json_pointer
                 }
                 else
                 {
-                    // iterate array and use index as reference string
+                    // iterate array and use index as a reference string
                     for (std::size_t i = 0; i < value.m_data.m_value.array->size(); ++i)
                     {
                         flatten(detail::concat<string_t>(reference_string, '/', std::to_string(i)),
@@ -785,7 +785,7 @@ class json_pointer
             case detail::value_t::discarded:
             default:
             {
-                // add primitive value with its reference string
+                // add a primitive value with its reference string
                 result[reference_string] = value;
                 break;
             }
@@ -821,17 +821,17 @@ class json_pointer
                 JSON_THROW(detail::type_error::create(315, "values in object must be primitive", &element.second));
             }
 
-            // assign value to reference pointed to by JSON pointer; Note that if
+            // Assign the value to the reference pointed to by JSON pointer. Note
-            // the JSON pointer is "" (i.e., points to the whole value), function
+            // that if the JSON pointer is "" (i.e., points to the whole value),
-            // get_and_create returns a reference to result itself. An assignment
+            // function get_and_create returns a reference to the result itself.
-            // will then create a primitive value.
+            // An assignment will then create a primitive value.
             json_pointer(element.first).get_and_create(result) = element.second;
         }
 
         return result;
     }
 
-    // can't use conversion operator because of ambiguity
+    // can't use the conversion operator because of ambiguity
     json_pointer<string_t> convert() const&
     {
         json_pointer<string_t> result;
@@ -926,7 +926,7 @@ class json_pointer
 };
 
 #if !JSON_HAS_THREE_WAY_COMPARISON
-// functions cannot be defined inside class due to ODR violations
+// functions cannot be defined inside the class due to ODR violations
 template<typename RefStringTypeLhs, typename RefStringTypeRhs>
 inline bool operator==(const json_pointer<RefStringTypeLhs>& lhs,
                        const json_pointer<RefStringTypeRhs>& rhs) noexcept

include/nlohmann/detail/json_ref.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/macro_scope.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -31,9 +31,15 @@
 #endif
 
 // C++ language standard detection
-// if the user manually specified the used c++ version this is skipped
+// if the user manually specified the used C++ version, this is skipped
-#if !defined(JSON_HAS_CPP_23) && !defined(JSON_HAS_CPP_20) && !defined(JSON_HAS_CPP_17) && !defined(JSON_HAS_CPP_14) && !defined(JSON_HAS_CPP_11)
+#if !defined(JSON_HAS_CPP_26) && !defined(JSON_HAS_CPP_23) && !defined(JSON_HAS_CPP_20) && !defined(JSON_HAS_CPP_17) && !defined(JSON_HAS_CPP_14) && !defined(JSON_HAS_CPP_11)
-    #if (defined(__cplusplus) && __cplusplus > 202002L) || (defined(_MSVC_LANG) && _MSVC_LANG > 202002L)
+    #if (defined(__cplusplus) && __cplusplus > 202302L) || (defined(_MSVC_LANG) && _MSVC_LANG > 202302L)
+        #define JSON_HAS_CPP_26
+        #define JSON_HAS_CPP_23
+        #define JSON_HAS_CPP_20
+        #define JSON_HAS_CPP_17
+        #define JSON_HAS_CPP_14
+    #elif (defined(__cplusplus) && __cplusplus > 202002L) || (defined(_MSVC_LANG) && _MSVC_LANG > 202002L)
         #define JSON_HAS_CPP_23
         #define JSON_HAS_CPP_20
         #define JSON_HAS_CPP_17
@@ -128,7 +134,7 @@
 #endif
 
 #ifndef JSON_HAS_RANGES
-    // ranges header shipping in GCC 11.1.0 (released 2021-04-27) has syntax error
+    // ranges header shipping in GCC 11.1.0 (released 2021-04-27) has a syntax error
     #if defined(__GLIBCXX__) && __GLIBCXX__ == 20210427
         #define JSON_HAS_RANGES 0
     #elif defined(__cpp_lib_ranges)
@@ -205,7 +211,7 @@
     #define JSON_ASSERT(x) assert(x)
 #endif
 
-// allow to access some private functions (needed by the test suite)
+// allow accessing some private functions (needed by the test suite)
 #if defined(JSON_TESTS_PRIVATE)
     #define JSON_PRIVATE_UNLESS_TESTED public
 #else

include/nlohmann/detail/macro_unscope.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -35,6 +35,7 @@
     #undef JSON_HAS_CPP_17
     #undef JSON_HAS_CPP_20
     #undef JSON_HAS_CPP_23
+    #undef JSON_HAS_CPP_26
     #undef JSON_HAS_FILESYSTEM
     #undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
     #undef JSON_HAS_THREE_WAY_COMPARISON

include/nlohmann/detail/meta/call_std/begin.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/meta/call_std/end.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/meta/cpp_future.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/meta/detected.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/meta/identity_tag.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/meta/is_sax.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/meta/std_fs.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>

include/nlohmann/detail/meta/type_traits.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>
@@ -13,7 +13,9 @@
 #include <tuple> // tuple
 #include <type_traits> // false_type, is_constructible, is_integral, is_same, true_type
 #include <utility> // declval
-
+#if defined(__cpp_lib_byte) && __cpp_lib_byte >= 201603L
+    #include <cstddef> // byte
+#endif
 #include <nlohmann/detail/iterators/iterator_traits.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/call_std/begin.hpp>
@@ -40,12 +42,12 @@ namespace detail
 
 // Note to maintainers:
 //
-// Every trait in this file expects a non CV-qualified type.
+// Every trait in this file expects a non-CV-qualified type.
 // The only exceptions are in the 'aliases for detected' section
-// (i.e. those of the form: decltype(T::member_function(std::declval<T>())))
+// (i.e., those of the form: decltype(T::member_function(std::declval<T>())))
 //
 // In this case, T has to be properly CV-qualified to constraint the function arguments
-// (e.g. to_json(BasicJsonType&, const T&))
+// (e.g., to_json(BasicJsonType&, const T&))
 
 template<typename> struct is_basic_json : std::false_type {};
 
@@ -53,7 +55,7 @@ NLOHMANN_BASIC_JSON_TPL_DECLARATION
 struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};
 
 // used by exceptions create() member functions
-// true_type for pointer to possibly cv-qualified basic_json or std::nullptr_t
+// true_type for the pointer to possibly cv-qualified basic_json or std::nullptr_t
 // false_type otherwise
 template<typename BasicJsonContext>
 struct is_basic_json_context :
@@ -239,6 +241,30 @@ struct char_traits<signed char> : std::char_traits<char>
     }
 };
 
+#if defined(__cpp_lib_byte) && __cpp_lib_byte >= 201603L
+template<>
+struct char_traits<std::byte> : std::char_traits<char>
+{
+    using char_type = std::byte;
+    using int_type = uint64_t;
+
+    static int_type to_int_type(char_type c) noexcept
+    {
+        return static_cast<int_type>(std::to_integer<unsigned char>(c));
+    }
+
+    static char_type to_char_type(int_type i) noexcept
+    {
+        return std::byte(static_cast<unsigned char>(i));
+    }
+
+    static constexpr int_type eof() noexcept
+    {
+        return static_cast<int_type>(std::char_traits<char>::eof());
+    }
+};
+#endif
+
 ///////////////////
 // is_ functions //
 ///////////////////
@@ -255,7 +281,7 @@ template<class B> struct negation : std::integral_constant < bool, !B::value > {
 
 // Reimplementation of is_constructible and is_default_constructible, due to them being broken for
 // std::pair and std::tuple until LWG 2367 fix (see https://cplusplus.github.io/LWG/lwg-defects.html#2367).
-// This causes compile errors in e.g. clang 3.5 or gcc 4.9.
+// This causes compile errors in e.g., Clang 3.5 or GCC 4.9.
 template <typename T>
 struct is_default_constructible : std::is_default_constructible<T> {};
 
@@ -335,7 +361,7 @@ using range_value_t = value_type_t<iterator_traits<iterator_t<T>>>;
 
 // The following implementation of is_complete_type is taken from
 // https://blogs.msdn.microsoft.com/vcblog/2015/12/02/partial-support-for-expression-sfinae-in-vs-2015-update-1/
-// and is written by Xiang Fan who agreed to using it in this library.
+// and is written by Xiang Fan who agreed to use it in this library.
 
 template<typename T, typename = void>
 struct is_complete_type : std::false_type {};
@@ -572,7 +598,7 @@ decltype(std::declval<Compare>()(std::declval<B>(), std::declval<A>()))
 template<typename T>
 using detect_is_transparent = typename T::is_transparent;
 
-// type trait to check if KeyType can be used as object key (without a BasicJsonType)
+// type trait to check if KeyType can be used as an object key (without a BasicJsonType)
 // see is_usable_as_basic_json_key_type below
 template<typename Comparator, typename ObjectKeyType, typename KeyTypeCVRef, bool RequireTransparentComparator = true,
          bool ExcludeObjectKeyType = RequireTransparentComparator, typename KeyType = uncvref_t<KeyTypeCVRef>>
@@ -586,7 +612,7 @@ using is_usable_as_key_type = typename std::conditional <
                               std::true_type,
                               std::false_type >::type;
 
-// type trait to check if KeyType can be used as object key
+// type trait to check if KeyType can be used as an object key
 // true if:
 //   - KeyType is comparable with BasicJsonType::object_t::key_type
 //   - if ExcludeObjectKeyType is true, KeyType is not BasicJsonType::object_t::key_type

include/nlohmann/detail/meta/void_t.hpp

@@ -1,6 +1,6 @@
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.11.3
+// |  |  |__   |  |  | | | |  version 3.12.0
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2013 - 2025 Niels Lohmann <https://nlohmann.me>