Merge branch 'develop' of https://github.com/nlohmann/json into featu…

…re/optional

.circleci/config.yml

@@ -1,6 +1,6 @@
 version: 2
 jobs:
-  build:
+  build_stable:
     docker:
       - image: debian:stretch
 
@@ -11,14 +11,38 @@ jobs:
           name: Install required tools
           command: 'apt-get update && apt-get install -y gcc g++ git cmake'
       - run:
-          name: Show versions
-          command: 'g++ --version ; uname -a; cmake --version'
+          name: Run CMake
+          command: 'mkdir build ; cd build ; cmake .. -DJSON_BuildTests=On'
+      - run:
+          name: Compile
+          command: 'cmake --build build'
+      - run:
+          name: Execute test suite
+          command: 'cd build ; ctest --output-on-failure -j 2'
+
+  build_bleeding_edge:
+    docker:
+      - image: archlinux
+
+    steps:
+      - checkout
+
+      - run:
+          name: Install required tools
+          command: 'pacman -Sy --noconfirm base base-devel gcc git cmake'
       - run:
           name: Run CMake
-          command: 'mkdir build ; cd build ; cmake ..'
+          command: 'mkdir build ; cd build ; cmake .. -DJSON_BuildTests=On'
       - run:
           name: Compile
           command: 'cmake --build build'
       - run:
           name: Execute test suite
           command: 'cd build ; ctest --output-on-failure -j 2'
+
+workflows:
+  version: 2
+  build_and_test_all:
+    jobs:
+      - build_stable
+      - build_bleeding_edge

.clang-format

@@ -0,0 +1,84 @@
+#AccessModifierOffset: 2
+AlignAfterOpenBracket: Align
+AlignConsecutiveAssignments: false
+#AlignConsecutiveBitFields: false
+AlignConsecutiveDeclarations: false
+AlignConsecutiveMacros: false
+AlignEscapedNewlines: Right
+#AlignOperands: AlignAfterOperator
+AlignTrailingComments: true
+AllowAllArgumentsOnNextLine: false
+AllowAllConstructorInitializersOnNextLine: false
+AllowAllParametersOfDeclarationOnNextLine: false
+AllowShortBlocksOnASingleLine: Empty
+AllowShortCaseLabelsOnASingleLine: false
+#AllowShortEnumsOnASingleLine: true
+AllowShortFunctionsOnASingleLine: Empty
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLambdasOnASingleLine: Empty
+AllowShortLoopsOnASingleLine: false
+AlwaysBreakAfterReturnType: None
+AlwaysBreakBeforeMultilineStrings: false
+AlwaysBreakTemplateDeclarations: Yes
+BinPackArguments: false
+BinPackParameters: false
+#BitFieldColonSpacing: Both
+BreakBeforeBraces: Custom # or Allman
+BraceWrapping:
+  AfterCaseLabel: true
+  AfterClass: true
+  AfterControlStatement: Always
+  AfterEnum: true
+  AfterFunction: true
+  AfterNamespace: false
+  AfterStruct: true
+  AfterUnion: true
+  AfterExternBlock: false
+  BeforeCatch: true
+  BeforeElse: true
+  #BeforeLambdaBody: false
+  #BeforeWhile: false
+  SplitEmptyFunction: false
+  SplitEmptyRecord: false
+  SplitEmptyNamespace: false
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializers: BeforeComma
+BreakStringLiterals: false
+ColumnLimit: 0
+CompactNamespaces: false
+ConstructorInitializerIndentWidth: 2
+Cpp11BracedListStyle: true
+PointerAlignment: Left
+FixNamespaceComments: true
+IncludeBlocks: Preserve
+#IndentCaseBlocks: false
+IndentCaseLabels: true
+IndentGotoLabels: false
+IndentPPDirectives: BeforeHash
+IndentWidth: 4
+KeepEmptyLinesAtTheStartOfBlocks: false
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+ReflowComments: false
+SortIncludes: true
+SortUsingDeclarations: true
+SpaceAfterCStyleCast: false
+SpaceAfterLogicalNot: false
+SpaceAfterTemplateKeyword: false
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCpp11BracedList: false
+SpaceBeforeParens: ControlStatements
+SpaceBeforeRangeBasedForLoopColon: true
+SpaceBeforeSquareBrackets: false
+SpaceInEmptyBlock: false
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 2
+SpacesInAngles: false
+SpacesInCStyleCastParentheses: false
+SpacesInConditionalStatement: false
+SpacesInContainerLiterals: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+Standard: c++11
+TabWidth: 4
+UseTab: Never

.clang-tidy

@@ -1,23 +1,20 @@
-Checks: '-*,
-         bugprone-*,
-         cert-*,
-         clang-analyzer-*,
-         google-*,
-         -google-runtime-references,
+Checks: '*,
+         -cppcoreguidelines-avoid-goto,
+         -cppcoreguidelines-avoid-magic-numbers,
+         -cppcoreguidelines-macro-usage,
+         -fuchsia-default-arguments-calls,
+         -fuchsia-default-arguments-declarations,
+         -fuchsia-overloaded-operator,
          -google-explicit-constructor,
-         hicpp-*,
+         -google-runtime-references,
+         -hicpp-avoid-goto,
+         -hicpp-explicit-conversions,
          -hicpp-no-array-decay,
          -hicpp-uppercase-literal-suffix,
-         -hicpp-explicit-conversions,
-         misc-*,
-         -misc-non-private-member-variables-in-classes,
-         llvm-*,
          -llvm-header-guard,
-         modernize-*,
+         -llvm-include-order,
+         -misc-non-private-member-variables-in-classes,
          -modernize-use-trailing-return-type,
-         performance-*,
-         portability-*,
-         readability-*,
          -readability-magic-numbers,
          -readability-uppercase-literal-suffix'
 

.github/CONTRIBUTING.md

@@ -66,6 +66,6 @@ To make changes, you need to edit the following files:
 
 The following areas really need contribution:
 
-- Extending the **continuous integration** toward more exotic compilers such as Android NDK, Intel's Compiler, or the bleeding-edge versions of GCC or Clang.
+- 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 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.
 - Extending and updating existing **benchmarks** to include (the most recent version of) this library. Though efficiency is not everything, speed and memory consumption are very important characteristics for C++ developers, so having proper comparisons would be interesting.

.github/ISSUE_TEMPLATE/Bug_report.md

@@ -47,7 +47,7 @@ assignees: ''
 
 <!-- Please add an `x` to the respective line. -->
 
-- [ ] latest release version 3.7.3
+- [ ] latest release version 3.9.1
 - [ ] other release - please state the version: ___
 - [ ] the `develop` branch
 

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Ask a question
+    url: https://github.com/nlohmann/json/discussions
+    about: Ask questions and discuss with other community members

.github/workflows/codeql-analysis.yml

@@ -0,0 +1,54 @@
+name: "Code scanning - action"
+
+on:
+  push:
+    branches: [develop, ]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [develop]
+  schedule:
+    - cron: '0 19 * * 1'
+
+jobs:
+  CodeQL-Build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+      with:
+        # We must fetch at least the immediate parents so that if this is
+        # a pull request then we can checkout the head.
+        fetch-depth: 2
+
+    # If this run was triggered by a pull request event, then checkout
+    # the head of the pull request instead of the merge commit.
+    - run: git checkout HEAD^2
+      if: ${{ github.event_name == 'pull_request' }}
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v1
+      # Override language selection by uncommenting this and choosing your languages
+      # with:
+      #   languages: go, javascript, csharp, python, cpp, java
+
+    # 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@v1
+
+    # ℹ️ Command-line programs to run using the OS shell.
+    # 📚 https://git.io/JvXDl
+
+    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+    #    and modify them (or add more) to build your code if your project
+    #    uses a compiled language
+
+    #- run: |
+    #   make bootstrap
+    #   make release
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v1

.github/workflows/macos.yml

@@ -10,7 +10,7 @@ jobs:
     steps:
     - uses: actions/checkout@v1
     - name: cmake
-      run: cmake -S . -B build -D CMAKE_BUILD_TYPE=Debug
+      run: cmake -S . -B build -D CMAKE_BUILD_TYPE=Debug -DJSON_BuildTests=On
     - name: build
       run: cmake --build build --parallel 10
     - name: test

.github/workflows/ubuntu.yml

@@ -10,7 +10,7 @@ jobs:
     steps:
     - uses: actions/checkout@v1
     - name: cmake
-      run: cmake -S . -B build -D CMAKE_BUILD_TYPE=Debug
+      run: cmake -S . -B build -D CMAKE_BUILD_TYPE=Debug -DJSON_BuildTests=On
     - name: build
       run: cmake --build build --parallel 10
     - name: test

.github/workflows/windows.yml

@@ -3,15 +3,66 @@ name: Windows
 on: [push, pull_request]
 
 jobs:
-  build:
-
+  msvc2019:
     runs-on: windows-latest
 
     steps:
     - uses: actions/checkout@v1
     - name: cmake
-      run: cmake -S . -B build -G "Visual Studio 16 2019" -D CMAKE_BUILD_TYPE=Debug
+      run: cmake -S . -B build -G "Visual Studio 16 2019" -D CMAKE_BUILD_TYPE=Debug -DJSON_BuildTests=On
     - name: build
       run: cmake --build build --parallel 10
     - name: test
       run: cd build ; ctest -j 10 -C Debug --exclude-regex "test-unicode" --output-on-failure
+
+  clang9:
+    runs-on: windows-latest
+
+    steps:
+      - uses: actions/checkout@v1
+      - name: install Clang
+        run: curl -fsSL -o LLVM9.exe https://releases.llvm.org/9.0.0/LLVM-9.0.0-win64.exe ; 7z x LLVM9.exe -y -o"C:/Program Files/LLVM"
+      - name: cmake
+        run: cmake -S . -B build -DCMAKE_CXX_COMPILER="C:/Program Files/LLVM/bin/clang++.exe" -G"MinGW Makefiles" -DCMAKE_BUILD_TYPE=Debug -DJSON_BuildTests=On
+      - name: build
+        run: cmake --build build --parallel 10
+      - name: test
+        run: cd build ; ctest -j 10 -C Debug --exclude-regex "test-unicode" --output-on-failure
+
+  clang10:
+    runs-on: windows-latest
+
+    steps:
+      - uses: actions/checkout@v1
+      - name: install Clang
+        run: curl -fsSL -o LLVM10.exe https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/LLVM-10.0.0-win64.exe ; 7z x LLVM10.exe -y -o"C:/Program Files/LLVM"
+      - name: cmake
+        run: cmake -S . -B build -DCMAKE_CXX_COMPILER="C:/Program Files/LLVM/bin/clang++.exe" -G"MinGW Makefiles" -DCMAKE_BUILD_TYPE=Debug -DJSON_BuildTests=On
+      - name: build
+        run: cmake --build build --parallel 10
+      - name: test
+        run: cd build ; ctest -j 10 -C Debug --exclude-regex "test-unicode" --output-on-failure
+
+  clang-cl-10-x64:
+    runs-on: windows-latest
+
+    steps:
+      - uses: actions/checkout@v1
+      - name: cmake
+        run: cmake -S . -B build -G "Visual Studio 16 2019" -A x64 -T ClangCL -DJSON_BuildTests=On
+      - name: build
+        run: cmake --build build --config Debug --parallel 10
+      - name: test
+        run: cd build ; ctest -j 10 -C Debug --exclude-regex "test-unicode" --output-on-failure
+
+  clang-cl-10-x86:
+    runs-on: windows-latest
+
+    steps:
+      - uses: actions/checkout@v1
+      - name: cmake
+        run: cmake -S . -B build -G "Visual Studio 16 2019" -A Win32 -T ClangCL -DJSON_BuildTests=On
+      - name: build
+        run: cmake --build build --config Debug --parallel 10
+      - name: test
+        run: cd build ; ctest -j 10 -C Debug --exclude-regex "test-unicode" --output-on-failure